[00:00:00] >> Good morning everyone welcome to the scenic technical web in our series. This technical open our series series of about 10 very an arson present and by our technical experts at the Southeastern nanotechnology infrastructure corridor which is an academic partnership between 2 academic centers of a large use of as abilities one is ours Institute Fila tonics and nanotechnology and our partners joint school of nanotechnology. [00:00:31] Not joins but of man of science and man of engineering which is and are going to be collaboration between the University of North Carolina Greensboro North Carolina and the university so obviously and for scenic is to be a premier micro nanotechnology and characters station resource in the southeastern United States and as a result of that our mission is to provide he c was had access to a wide variety of micro one nano fabrication and categorization concept and process capabilities along with our staff expertise to the searchers and nanotechnology So in short it is a nano scale fabrication and characterization resource and how do we do that in all our users banned from not only our local Georgia Tech and j s and users but also we have the provider use that access to off campus researchers from both universities and industry startups Fortune 500 companies and in some cases gone regarding solutions such as c.d.c.. [00:01:43] So there are 3 Sally and features of why $11.00 should or one would be used or it was a fascinating one as is the easy access so a user who would like to use and access the facility from off campus may be able to sign up and use that argument and start using the facility after getting necessary tool training on a piece of coal that they desire to use Number 2 it's cost effective you know someone starting a start a company or a lab and university then it's easy for them to go ahead and you know get access to this large facility which is estimated to be about $200,000,000.00 So and the so it's very cost effective number 3 is fruition of staff expertise so we not only train our user and let them use it on their own but of the same time the office staff expertise which means our staff experts come alongside with our users and support them during the course of their research using our facility so more information is available at the site scenic dart Gattex dot edu so you can scroll through that and also all the way even our 2nd little robin our set already posted in that site so if you missed anything in the past go ahead and visit that site and view these very large and in one word or in one line scenic is one stop shop for your nanotechnology to certain needs with that said about scenic I want to give a quick promote the upcoming technical writing are by Dr Mangan 50 and he'll next week that's our last technical of everything are there to be on June 25th which is again Thursday at 11 he'll be talking about on his topic insitu eating techniques and transmission electron microscope or stem analysis and there's an upcoming scenic ambassador of having our scenic ambassadors or faculty members at different. [00:03:42] Newest to campuses who support scenic interest in their own individual campuses and so we will have 4 active members from 4 different universities Louisiana Tech Georgia State University and University of South Carolina and Louisiana and as well as Kennesaw State in the us it's a big. That we'll be speaking to was so feel free to sign up for that act if you have signed up for one of these technical side narcs you will get an invitation and so you'll be able to sign up for that but with that said it's a pleasure to invite my colleague Mr Van Hollen back to speak on this topic fundamentals of what I'm asking design Mr Ben Hollaback is a process if you're from an engineer at the Georgia Tech Institute developed Mannix and then of technology you started working for i.b.m. into those and fight while a store into Georgia Tech after receiving his bachelor's degree in industrial design he began working full time at the I Am and in 2009 to cover the management of i.e. and smart shop for the past 11 years Ben has managed the evolution of for the mass production from the use of a 21970 s. era. [00:04:58] This year man pattern generator and stepper through 1st generation laser writers to today's modern hard labor game really one for the mascots eyeliners of you're one of the users would not have missed seeing then is our very act of. Staff explored in our present it is supporting both internal and external users with that said I'll ask Ben to you know it was his presentation on fundamentals of forum asking a sign Thank you Ben thank you very much. [00:05:34] Good morning everybody Paul thank you for having me allow me to talk this morning I hope what I'm going to share with you today is. Part of mass as I am but also kind of goes into a little bit more of the. Live a little bit of the advanced parts of how you can better design for both photo mouse and direct like right things that's kind of one of those where in the world a photo mass we always kind of base everything on what came before and nowadays we rarely ever use but it masks specially in the eye and we do a lot more direct right but the principles are still the same regardless if you're making a plate or not so much this morning I want to talk about 5 different areas 1st we'll start off just. [00:06:18] Based understanding through the vocabulary the different production styles how photo masks are made were made how are currently doing direct write. Design final format and software this is kind of like the big one is to how do you take an idea that's in your head or the sketch on a piece of paper and convert it into something and actually be produced and then considerations for both production and fabrication of your photo mask and your photo masks that. [00:06:47] So start with the vocabulary let's look at a Fermat's blank so if you're working with a photon mass it's going to be a glass substrate typically either courts or subtle lime that is covered with a thin layer of chrome back from has a layer of anti reflective coating on top of it and then there's a top layer to resist our mastery they're typically a z. 1500 or. [00:07:11] 800 Typically you want something fairly thin it's always a positive resist and it's something that's kind of easy to work with com and easy to develop on the glass side you're going to see either courts or set a line for a couple of different reasons courts is going to be your ideal material best for light transfer has the most uniform planar surface it's going to be the best if you're trying to do d.p. of the exposures or if you're trying to go with high density small features anything typically below 11.2 microns specially if you're going into the 100 nanometers range courts is going to be your best friend if you go a little bit larger and sample future sizes you can go to something like center line it's it's not quite as good for for the transference but it's dramatically cheaper you're looking at paying one 3rd quarter the price for sort of line play as you would be for a court split so if you're going to be producing a lot of masks and you're a feature size isn't going to be very large Anything above 2 microns actually you can get away with one micron sometimes with with set a line. [00:08:17] You don't necessarily have to invest the money in the courts and so you can just save yourself some money long run. Water wise don't try to make your own phone or math just buy them pre-made they're not really expensive acetylene plate will cost you about $24.00 and the difficulty in trying to put down a relief and uniform layer from unthinned uniform layer resist can just be a massive headache there's plenty of companies out there that do really great job of this disco headed by them you yourself. [00:08:46] But I must to really comment a variety of sizes 4 inch province and 7 inch have been our standards here at the eye and you can find other sizes 3 inch 2 and sixpence up to 8 and 12 as well one thing to keep in mind is you want to plate that's always going to be at least one inch larger than the substrate you're going to work with so a 5 inch mask is ideal for a 4 inch wafer 7 inch mask would be ideal for a 6 inch way that's for the fixtures that you're going to use on a mass killers you need that additional space to be able to hold the mask and clearance of your substrate below we don't go below 4 inch even though a lot of our users may be working with 2 inch wafers or even small pieces managers because there's not a whole lot of demand for pacifically like a 2 inch mass plate and a 4 inch mass can be used for anything smaller than that fairly easily. [00:09:42] Polarity So you're going to probably see plates fall into 2 categories either a clear field plate or a dark field a clear field is going to be a plate that is primarily glass with a little bit of chrome leftover turkey ales the exact opposite can be primarily chrome with a little bit of glass looked up so the dark field place can be more like a window looking through a clear field play it's going to be more like it's an inclusion in your point of class why this matters is going to depend on what type of process you're running for certain applications Clearfield is going to be more suited for other applications darkfield may be more suited to example let's look at the Clearfield played with the negative resist what you'll have happen is the majority of the field to resist will be exposed after development that material is going to retain and you're going to get a negative wall Ingle in your photo resist this negative wall angle is going to be great for a process like a metal lift off where you can deposit the metal keep it clean surface of the side wall and so when you do a lift off you can retain really nice metal pads at the bottom of the resist if you're using a positive resist in a clear field plate in this instance you have a positive side wall and your left off will be much more difficult as you're trying to break that metal layer for the adverse if you're using a dark field plate and you're positive resist you're going to get a positive angle side and what that kind of I was really nice sharp corners at the bottom of the resist you can control your dimensions there really really well and this can be great for when you're doing things like etching and so you can use that positive side wall to mend sure that your etching dimensions are exactly where you want them but once again if you are going to be using a negative resist with this type of plate and you have that negative side well then they can kind of cause a little bit of a cavity down there at the bottom of your existing create maybe an adverse a **** characters. [00:11:41] Parity we often talk about plates either right Reed chrome off or right Reed crane down the difference is how the place going to be applied to the surface you're typically credit plate right Reed chrome down and that way when you place the chrome surface against yourself straighten the expose then the transferred pattern will work correct or right Reed chrome up play placed or atop a surface will have that Glasscock in between and your transfer will not be a very good look at this diffused included pattern another way that I like to think about this is a left hand right hand rule So imagine you hold your 2 hands facing up your right hand is what you want your wafer to look like you have to create your left hand mask so when you take your left hand over top you're right they match each other and so when you're designing this you're never going to design for the mask is going to look like you're always going to design for what you want your wafer to look like but you're going to and make sure that in the set up of your design files that you make that change prior to the exposure that's typically something that's done in the interface the tool software just making that mirror left or right near for each other. [00:12:53] One place the parity becomes more complicated think about when you have top side and backside masks so if you have the substrate and the mass that exist on the top would be inherently right recrown down the mass there exist on the bottom would be to be right Reed Kramer to correspond to the design on the top side of the substrate so these are start to working on your mass sets and if they have back side masks you will not want to flip those because naturally when you flip the wafer over you've made that correction and so make sure that as you design them you think about that in your head about backside masks stay right read from up top side masks are right Rico down. [00:13:39] No I was times when you have masks made by outside companies they're going to ask you sir from for some basic information that's going to be useful to determine pricing and required tolerances would require exposures Meskin to be a total pattern dimensions in x. and y. and then you're also going to be looking at the smallest gap dimensions and it's not often called these are critical dimensions the smallest depth the mentions could be either positive as we look at the very bottom line where the actual thickness of that line or it could be negative it could be the gap between 2 features depending on what you're trying to do and what elements are critical that could be a need to preserve that space or need to head that dimension and that can change kind of how the mask is produced based on what you're trying to achieve out of it now let's talk about production styles how these masks are made traditionally there were 2 different production styles pattern generation and laser the fogger the pattern generation is going to be the oldest for our old man to see a tools. [00:14:43] Operate in this way and where we see here is it having on the majority of the stock size square and then it tried to handle the curves with I rotated square underlaid lithography this is going to be much more closer to how a inkjet printer works if it's going to stand back and forth and prints with a single line across the entirety of the pattern. [00:15:07] Now we'll look at this as I mentioned this is an older style that works with the flash exposure so it's going to flash each square and then move on to the next where in Flash and so on and uses a rectangular app which is great for giving your really sharp corners and nice square straight lines but it is a horribly for current stuff you're trying to do a sine wave type feature or something more than that the pattern generator is going to step that entire curve. [00:15:38] And for certain applications it could be really really Unfortunately Pat One area is a kind of became really difficult if you're trying to build light channels the stepped walls of the exposure profile could really destroy those like channels and there were tricks people would try to do were there to actually. [00:15:59] Use a softer contact for their exposure to try to deaden some of that angularity but it was really something that was hard for come as we moved into lasers progressivity we started to fix some of them we now have a circular beam we have shrunk in our spot size typically you'll see ways or tools at about one micron maybe down the $600.00 nanometers but because of the circular being there much better curves they're much better complex geometry but they don't provide sharp corners and if you're trying to do really really small squared features you just can't do it a one micron squares and exposes a one micron circle a 2 micron squares a circle or square hybrid with a half Micron radius and so you kind of get a little bit of that trade off as if the laser is maybe much better at providing nice smooth lines but they're much worse at providing squaring off objects one of the other big benefits of laser the fogger see it is typically dramatically much faster than the old classic space systems that we used before. [00:17:06] A certain area which is a new feature that the lasers have given us the ability to do is Chris Gallus like this is a dosage modulator exposure where we can create 2 and a half day type objects by exposing different areas of the resist at different dosages and so as the material is exposed and we we only have that absorption occur at certain depths then we can kind of create different profiles within a resist this is great for building things like. [00:17:39] Maker fluidic devices or small nanostructures but it's also very tricky because there's a lot of tuning that comes into play typically if you're trying to. Expose just to standard resist you have to determine what the dosage is for that resist at that thickness at the feature sizes you're trying to achieve to go into grayscale you're not trying to develop a dosage band that gives you a profile that you can work with and so there's a lot more fine tuning that comes from let's talk about file formats and software next. [00:18:14] Typically you'll see for different file types that exposure systems will use defense g.d.s. to c.f. and bitmap are pretty much what you see across the board the excess is going to be your super universal Pad format everybody uses it everything is available on it because it is so ubiquitous but it's not necessarily something that is well tuned for this process g.d.s. 2 and c.i.s. are kind of the forefront of i.c. design and they are specific file formats for this type of application but they are much more robust much more well suited for this purpose but they're also are very dated so they may not have the same kind of cutting edge features and you may see end of the access type. [00:19:00] And then pit mouth is really useful for grayscale and really not useful for anything else the pixelation of bitmaps can cause you issues if you're trying to translate that into an exposure and oftentimes the resolution there is what hurts your ability to make good exposures outside of the great skill you are looking at this panel effects ability vs fidelity the universe ality of the excess makes it amazingly flexible The men met a things that you can do with the amount of places the file format can be useful across the charts but it's not very good for mass and it's native form it's doesn't preserve fidelity very well you have to be very conscious about how you use the decks that format where T.V.'s and C.A.'s being much more designed for this world are much better controlling the fidelity but they may not have the flexibility for you to constantly be if you if you take a file from somebody else the ability for you to edit it very easily without having to go back through a massive tree structure that map kind of falls into the middle but a lot of that is going to depend on how you produce that's why there's the asterix there are certain softwares you can be able to handle but mounts much better other software is maybe too much and it might be a situation where the best bitmap you produce is actually produced in software that doesn't natively work in bitmaps but you can export. [00:20:28] So we look at common cad software if you're going to be seeing a lot of people using things like Autocad or possibly linked to develop their dx s.. As a general purpose tool there's so much complexity in here and they're constantly updated that there's a lot of new features that you might find super interesting exciting to use that you really just can't there's too many things that the. [00:20:50] Mass writing tools just aren't able to understand you really have to dumb down your dx a couple of key areas here is blocks in groups a lot of times if you're designing a singular die and you're repeating that tie over you're going to build things in blocks in groups and arrays and a lot of times those conversions don't work very well and at the access you want to break those out you want to explode all of your blocks and just keep them and singular figures hatching in training is something that also trips up a lot of the software's And so the image you see here on the right is going to be pretty much what you'd see within an auto cad world everything is this. [00:21:26] Thing or line something is filled and and so as you try to think about what this is going to look like and opaque versus transparent exposure you have to really kind of focus on that it's not going to be explicitly ssion to you people off the hatch and change things to help fix that but the hatching and changing that super tripped up and so you have to make sure that's removed and then finally you want to make sure that everything is made close polygons specially use the polyline tool to do this. [00:21:56] If you try to make everything out of singular line segments the system doesn't understand what that is it's a 0 thickness object and so we'll take a single line segment typically booted out and Eleanore whatever they don't do you have to close all these features into continuous polygons you cannot group them if they still see a group as individual line segments they have to be continuous poly ones also on account of the unit was designed program it doesn't ask for you to dictate what the the unit is you have to go in there with the unit in mind and for mask writing the number one way to do this is to write this as a one micron feature so one unit equals one microns you keep That is your standard thought everything is going to turn out great if you do it in something else if you write it as a one unit equals one millimeter you will typically have to do a conversion and you might lose some tolerance for that would be in that there are some assumptions that can be made cad as it comes to how many decimal points are kind of out and so the more accurate you can create your subject it the better off you typically know that being said don't draw it and then a meters because now you're adding them is an extra layer of complexity that the system sometimes don't like to compute. [00:23:06] And then finally with articles make sure you pack save them as I said these are constantly updated softwares a lot of times the conversion software is you're used to make this into a mass credible file aren't and they don't understand the newest versions it's always best to fax after a fairly old version and or 12 is about as always you can find and they typically prefer an ascii format over by Mary met kind of make sure that convergence comes a lot smoother. [00:23:31] In the I think it on world you're going to see most likely one of these more programs cadence magic and play when these are specific tools for this purpose they're focused on circuits they're focused on producing objects for the semiconductor world they've been the standard for a long long time and so because of that they're really catered for solving the problems that have been around for the last 40 or 50 years they're really good at organizing their way or breaking out if you're trying to build a mask set it's really easy to develop mascots in the software it's really easy to build a singular die with multiple layers and expand that died to be a more wafer and conserved layer organization and you also have an exposed what you see view so looking at the image on the right everything that shaded then will be exposed and we can look at this as a possibility that we have 3 layers we can also look at this as maybe the blue layer and the green layer will be converted and printed whole and all of that becomes really nice and clear for you to see Will drawing it and so you know what you're going to get on the other cad world you always have a little bit of a let's see what happens approach when you upload the on cad file into conversion software. [00:24:46] One thing that is different about. Cad the i.c. cad and more common time is I see cabs typically very chair metric focused so it's really got it just wrong simple oxen lines and circles and stuff but complex curves really organic shapes Autocad is typically a little better at their ability to use spline tools and little bit more freeform. [00:25:09] Gives them the ability to get a little bit better and so if you're going to be working with things that have a really flowing organic design you might want to lean towards other cat and that might be the only place that this has a really good advantage. Couple more software concerns solid work sketch up are things that a lot of people have a lot of people use for other purposes and they're solid work has become popular for people to kind of build out what their devices will look like on the layer by layer approach if you import or export files from those software and try to run them they will not work they are never ready to go they always require further editing so it works you can have shapes that are Lanka's as. [00:25:52] Linked together and the moment you export them in the access and breaks everything up into line segments and you have to go back and retrace them so if you're if you're wanting to use that to mock up what your devices are going to look like 3 d. that's great but you're going to have to fix that problem and using one of these other softwares before you have to write a book file. [00:26:13] Illustrator and Photoshop are great for your greyscale works if you're trying to develop bitmaps I love using illustrator to to develop greyscale bitmaps because I have really good control and how I adjust my gradients and I can drill the form nice complex greyscale shapes by using this tool. [00:26:33] The song a couple of different variances and the actual development of these designs 1st office text the excess text typically always translates it's vector face like everything else can be accessed it's really well understood it almost always works G.D.'s and say I may not it depends on where it comes from it depends on sometimes the fun choice that used to visiting to do is to take those and explore them out into actual polygons and you don't worry about that being a problem lines lines are handled in 2 different ways and I mention this before the excess a single line saying with a 0 thickness object is not right a bill to a line has to be a polyglot from designing. [00:27:20] A die and it has 10 micron lines that connects different paths I have to draw a 10 micron thick rectangle to make that line axis and I see world it's going to be 2 reference points or multi reference points and then a fixed positive line. You cannot build lines typically and those tools that have variable length with She'll have to build multiple line segments to accomplish that but it's going to be able to take that information extrapolate it into an explosion. [00:27:52] And then this is just a really good rule of thumb for reducing some of the complexity in your designs. The convergence of sources on files to write about files are very limited on the number of verticity a 1000000 birds per design it's pretty standard $2000000.00 per feature 200000 per feature is also fairly standard to have a super complex a lot of vertices designed like this one in blue right down here it might freak out when it sees that best thing to do is think about the as a small segments are kind of break them up and segments can still printed in the exact same way but it's going to be able to compute each of those segments easier than the whole of this massive single design the law because things probably guns make sure that all of your polygons are connected and are close shapes Don't allow your poly lines to overlap each other if you cross over the poly lines or a single shape shares the same endpoint they can kind of freak it out a little bit during the convergence and then one of the things that I like to push is a good trick is if you have to shared lines with from 2 different shapes within your design it will take that sure line and Elix pose over it as it's one complete thank you so if I wanted to create this donut shaped right here I could do it simply by making it to see shapes having them have shared lines and it's going to print this is one content that's one way that you can kind of decrease the complexity you're trying to work with and look at the end result to look great. [00:29:30] And then finally as you go through and start to manipulate some of your files with Andy's writer softwares you're going to often come across the options to our cut x. or you are designs I just want to cover this real quick so imagine here in the middle we have might get to figures one from Layer 11 from layer to overlap is a joint overlapping regions functions and it's going to take those 2 figures and it's going to combine them into one cut that's pretty much exactly what it sounds like it's going to cut layer 2 out of way or one and we're going to be left with the c. shape and then x.o.r. stands for cut overlapping regions and it's going to take this period right here in the middle where the 2 features overlap and it's going to remove that from the design kind of print the left half specially left after the rectangle on the right half of the circle and it's going to leave that void to be extremely useful and kind of further manipulating your designs but my always rule of thumb on this recommendation is don't require this type of manipulation you can create all of these figures and your source can fairly easily just allow the cad to do. [00:30:39] Ok let's talk about some production concerns in your designs 1st off exposure limitation and the mentioned earlier when you're using around spot size you're going to be limited to that round radius even if you go up and sizes you're still going to have that radius to exist within your designs it's something you just have to kind of contend with using a laser system dear little bit limited if you need really really sharp small features as to how you can do is some systems do allow you to expose with a vector base and so you could potentially draw a line segments and have them over intersect each other to create sharp corners but then you're dealing with like a negative versus Ponsonby reproach on the pattern generator side because the squared aperture as you get smaller smaller and circular features they get more and more based geometric to eventually they just become a square to if you're trying to do small circles and using a pattern generator they're never going to turn out very good because of the limitations around the aperture size and the squareness of the aperture now the laser writers will always write with harassers exposure so though right similar as I said to like an inkjet printer where they're working left and right up and down they will also break that Ruster exposure into a series of strips and said All right that's left hand strip movement right the next trip we were going with the next and so on and so on. [00:32:11] If you are using small line segments that cross multiple strips and this can cause an issue vertical lines are that exist within a single strip are going to be just fine but horizontal lines that are going to break across multiple strips walk be written in small segments that will write the segment then the segment then this segment and so on what can occur here is you can start to see some stitching errors occur the ability for the laser writer to write their strip returned to the spot and then write this section and continue on that script and return and repeat can cause an overlap concerns and can cause some kind of special recognition concerns will it hit this and points perfectly as it goes to the next trip now as your lines get thicker this becomes less problematic but for very thin lines we can start to get the stair step where we're not quite sure how straight and continuous The line is and retake away those marks you can see this it can be fairly Jack and the other concern is how our stitching is going to be set up if your stitching step is too wide you can start to see the little dips into our line where we've actually missed exposed in the 2 lines of blade together but not very well if we're stitching step is too narrow then we get these areas that were perched poacher and they can kind of pull itself out this is one of those that it's a concern to putting on what type of system you're using for certain systems this can be very problematic typically in older laser either this is going to be where the problem exists. [00:33:39] If you find that you just sign has a lot of narrow pen lines running horizontally and not so much running vertically it might be best for you to actually rotate your pattern before exposing it to take those horizontal lines in our roof and exposing vertically that kind of overcomes. [00:33:56] Now this is a problem for laser riders about 10 years ago but they've made changes that have worked on fixing this because this was such a large issue and we now see a new roster exposure system that's an overlap system rather than moving one full strip over and exposing next trip as right times have dropped in the speeds of these writings have gone way up we can use an overlap system so rather than making that one step we'll do partial steps and we'll also be able to write in both directions so we'll just kind of progress like this. [00:34:28] Using a dual direction rider and using overlapping strips we can apply smaller dosages per exposure and so will build up doses just based upon the number exposures which can increase the tolerance critical dimension tolerance of those exposures and dramatically decrease stitching errors and so we can virtually get rid of stitching errors I can draw a one micron line that goes from 8 inches I want to have a perks and you may not see a more than $100.00 and a meter variance from the beginning to the end of any point it's going to hold it really really nice and straight as you go up and scale it becomes even more intense this is going to really create benefit a new systems is to get rid of that stitching issue that we would see now some real briefly about greyscale greyscale I find is the most personal of any sort of these with larger fear is the questions in the problems you're going to have could be very very specific to your needs but we're trying to talk about formulaically how you want to go about producing greyscale features so we're looking to try to create a series of Botox here on the right and we're going to need a pattern that looks something similar to this on the left to do so a field of black would be a full exposure in the areas of white would be 0 expect. [00:35:47] So how do we determine how to make this pattern produce these features Well we start off having to do a greyscale test so we start off with a pattern that takes her to our full 0 to 100 percent pass to be black. And we will expose this and our full range of 0 percent intensity to 100 percent and what we would expect to see is a curve a look something like this red line based upon that we're going to be looking for this area of the most linear change because we want to be able to control that exposure range that's close to $1.00 to $1.00 spot one percent change and greyscale would be a one percent change in intensity or something is near that as you can. [00:36:33] To running this full test to prove 0100 percent can give us the range of where this exists now from here we have 2 options we can either say Ok this is kind of the start of early in the area down here this gray range and going up to this branch of the end of the linearity we can designed based upon this great value to this great value kind of reassigning 0 to one the other thing we can do is you can recast based upon the intensity we can determine what the intensity value was at that point and say this is going to be our new 0 points and then create a new 100 points based on the end of the intensity and we would run a 2nd test like this and based upon this test we can profile the resulting feature and determine what that slope is to see what that actual percent change is and then we can use that based upon our. [00:37:27] Geometry needs in the design to then adjust what our great scale looks like and so for Imagine trying to apply that if we take this middle gradient here which is just a perfectly balanced gradient from 0 to 100 we would expect expose a line that looks something like this. [00:37:43] If we began to shift our greyscale curve to where now we have a much further shift to the apex we would expect to have a negative curve like this and then same thing here are moving the black apex inward we would expect to have a curve something like this and so as you start to adjust the. [00:38:03] Distance from 100 percent to 0. Were the apex of your slope you can start to manipulate what the resulting feature looks like. Ok let's talk about fabrication and this is really focused on multi-layered work so we spoke a bit before about critical dimensioning and how the critical dimensions could be either a positive or negative approach but when you're working with multilayer exposures the critical dimensions can either be a gap between 2 features or the relationship from one layer to a next and often times this is kind of where you're most concerned I need to make sure that the dimensioning of mass quantity mass 2 are close enough together that when I align these pads they show up right there in the middle or ensuring there's no overlap and this can often occur when you have one design that uses very large features and another design uses much smaller features you know I don't need that much tolerance and the 1st one because I have giant pads but you need to make sure that that the tolerance that 1st once produced to match the 2nd 12 you don't have any alignment issues now how do you align these 2 well you need them align x. and then mark that I suggest everybody to use would be just be a simple cross now you could do it one of 2 ways either the crossing blocks or the cross and frame like this either one is still going to work great the reason why I recommend Cross is it's really easy to see when you have a variance in alignment I'm just going make a slight shift here and you can look at the one on the left and say yeah that crosses the Blue Cross has definitely been moved to the right and slightly down and we can also say it's been moved further right than it's been moved down relook at the crossing the last we can say there's a stain a change there's clearly a rotational change in these type cross ups make it really easy to recognize the difference between good alignment about alignment and also direct how to correct them. [00:40:05] When you're doing multiple layers you're going to want to organize your crosses to handle that so I recommend putting down a base block on Layer one and then creating locations for alignments for each color layer layer to layer 3 in their forward so much so Also depending on the if you're clear field of dark field you're going to also want to be cautious about if your line marks are clear field or dark my recommendation is to try to make sure all of your alignment marks kind of fall into the same design standard and you create a clear field when that was the minimum so you can actually see the alignment point well this is going to allow you to find when your marks are nearby and you're not trying to look through the tiny window that in the cross you're just simply looking around the cross the other thing you'll notice here is every single alignment Mark corresponds to the base layer so we don't want to we can get away with that we don't want to align layer 2 to layer 3 and layer 3 layer 4 because any alignment shifts that occur will just perpetuate through that alignment if we can align everything to the base layer then any alignment shift that occurs should be fairly consistent on every other layer so there's a small variance between layer one and layer 2 that same variance would exist between layer 3 and layer one but way or 2 in Layer 3 should line up much closer so we can kind of preserve overall alignment accuracy by using a fixed alignment points which is near one. [00:41:38] When spacing a lot of marks out onto your way for you want to place them in a wide range of areas. This is just a kind of a general loose example but I have a series of 4 alignment points across the x. axis and I only have 2 alignment points across the y. axis if you can put a line of marks all over your wafer that's going to help for a multitude of reasons 1st off as you process their way for more and more the less marks on the edges might get damaged based upon fixtures or just how your processes work if they're centrally focused if any points in the of these alignment positions get destroyed then you have other positions to relate to also if you can work with further on lab marks it's easier to recognize data changes if you're working really really close to the center the magnitude of a rotation will change is not very large and you might miss it if you work further out you can kind of accommodate and I also like to include marks on the y. axis as that helps as a comparison as well if things get really bad you can still work with that you might have to rotate your plates but it still gives you options you also may think about if you're doing backside alignments are your marks visible by the backside cam and when we have. [00:42:55] Him a 6 mask on liners they have 2 windows that exist kind of in that region there we want to make sure that we can have our line marks exist in those backside windows so we can align to if we don't have any marks there it's going to be really difficult to do back when. [00:43:12] And then finally let's talk about pricing here real quick so the kind of used a couple of times here on the left will actually be a horrible pattern for Tyson to prevent in the ability for us to stock devices together but if I need to extract one device I'm going to kill a dozen others to do so if you know the going to have to break up your design and package of all sizes you need to make sure that you make that clear in the region space and then exempt so you have clear deicing paths and give yourself some buffer to do so so this is a kind of applicable to our deicing system here but I recommend it got there about 750 microns from me that's to me that edge to allow us device through that typically you can get away with a lot smaller space but if you can give a 750 Mike or Micron gutter you're almost assured never to facing damage any of your devices and specially if you're pushing really sensitive devices near the edge you need to be really confidence that they're not going to get damaged in the process. [00:44:16] Ok so just kind of go through a summary of what we've talked about here clear field versus dark field as you start to think about how you're going to be composing your designs for your fabrication you're going to want to think about the combination of your the saga fi and your resist choice and what steps are going to follow this to as I mentioned before Clearfield plus negative resist is a great help for liftoff darkfield vs positive resist is great for etch think about right recurring down versus chrome up and the alignment of your masks for your needs if you're going to be doing backhaul I mean you're going to need those masks to be cruel Well we have a few different ways that we can produce program masks hern generators can be the old style that's much slower it uses rectangular racing to produce really nice sharp features but it's been by far passed over I don't know very many people to still use those they've all gone to laser much faster much easier control much more flexible but they have that circular behave that can cause some issues if you're looking for a nice sharp corners great and new frontier as people have been able to push the laser tools into doing. [00:45:25] More new and different things the ability for greyscale to create things to the features to not to features can allow you to really expand upon what you're working with. And how you produce. The device is going forward within the design file area it did except it's going to be the most ubiquitous it's going to be the easiest for people to work with they typically can always get autocad but it's some of the harder files to work with just because of how generalized those. [00:45:55] If you can get your hands on one of the I see it as an softwares g.d.s. and siestas to play going to be the best way to go. With in our clean room we have a computer the next time Heidelberg number one has software on there that allows you to convert to access to CIA often I often recommend people that you do that to try to build some or that Fidelity into your design files the access has those issues around the complexity Please reduce things like hatching and shading get rid of the blocks and make sure you're always working with close colleagues. [00:46:35] Or you talk about circular being versus a square corner issues when you're looking at the rest or exposure just recalled you're going to have this potential for stitching errors if you can understand where they're stitching errors can exist you can kind of manipulate your designs around them would hopefully everybody is using a tool that uses overlap raster and that's going to fix that problem too it kind of goes out of the way greyscale if you can go through the process to test and develop your exposure curves you can really create some great bitmaps the current creates some great features but you also need to be aware especially with Chris Kate about the stitching situation that we're trying to produce non-linear exposures ditching can be a nightmare for that type stuff to also be very conscious about. [00:47:26] Looking in the multilayer fabrication cross the line marks are going to be the most accurate and easy to line features you always want to make sure the Align to that 1st layer can preserve layer fidelity across all errors include the landmarks across all aspects of your wafer and then plan accordingly for further usage of that device if you're going to be dicing it or packaging it anyway you need to plan for that at the get go so you're not surprised it's when you get to that point you don't know what to do what you're doing. [00:47:58] Ok well I thank everybody for your time and I'll be more than happy to answer any questions you guys may have thank you. For your presentation. And it's time for questions let me see if those questions. There's another question from such and he was asking Has Ben came across masking for employers to a more obviously deposition many people do that and he was asking you if you if it works just mask for little Graffy I mean I I walking only for the mask for that little graphic. [00:48:57] Demon understand that question though yeah I'm not I'm not quite sure either. Yes or no. Comment From don't go great presentation on the graphic mass production really good information thank you well if there are no questions. Let's thank them one more time was really and I appreciate. Your time. [00:49:28] And thank you everyone and we'll have our last seen of dignity by the next Thursday at 11 so you all and have a great day by.