text stringlengths 1 2.97k |
|---|
> |
> Below is a picture of a sample right before exposure, taken using our |
> MLA150. The dark/bright features you see are NOT etched on the wafer (these |
> wafers were never etched). The marks are from a previous lithography test. |
> They become apparent after coating the sample with LOR 5B and even more |
> after adding AZ 1512. And I don't see them when coating only with AZ 1512 |
> (I reused wafers for that process development without any issues). |
> |
> And what is more intriguing is that these features affect |
> exposure/development of my test mask. For instance, on a virgin sample I |
> can expose and auto-develop with the same recipe (dose and development |
> time) I use for the manual process. On a reused sample, the reisst stack |
> behaves as if it were underexposed (a dose test made this very obvious). |
> |
> |
> |
> Here are the steps during my tests: |
> |
> 1. Piranha clean |
> 2. HMDS prime on a YES oven |
> 3. Spin-coat with LOR 5B/AZ 1512 (marks show up on a reused sample) |
> 4. Expose using either a mask aligner or DWL |
> 5. Auto-develop in our Laurell EDC-650 (resist seems underexposed over |
> the marks) |
> |
> |
> 1. AZ Developer 1:1 ? 90 s |
> 2. Rinse (DI water) and dry (N2+spin) ? 60-120 s |
> 3. MF-319 ? 5 s |
> 4. Rinse (DI water) and dry (N2+spin) ? 60-120 s |
> |
> |
> 1. Strip resist with Remover PG |
> 2. Repeat all steps for every iteration |
> |
> At first I thought that this could actually be some etching of my Si |
> wafers by MF-319, even though unlikely given the low TMAH concentration |
> (and I'm not sure why that would affect exposure/development). But the |
> sample in the image above has 2 ?m thermal oxide, so practically impervious |
> to TMAH. Not to mention that the brightest crossing marks come from testing |
> a recipe where TMAH was not used at all. This must be some strange |
> interaction between LOR 5B and the sample surface, which I'd expect to be |
> practically reset after piranha and HMDS priming. |
> |
> |
> |
> My search for more information regarding LOR 5B and it's sensitivity to |
> surface conditions has proven fruitless so far. And requiring a brand new |
> sample for every iteration can get expensive quite quickly. We'd appreciate |
> it if you could point us to some references where this was discussed in any |
> form, or if you know of a method to avoid this from happening. |
> |
> |
> |
> I'm sorry for the long email, and thank you in advance for any comments. |
> |
> |
> |
> Best regards, |
> |
> -- |
> Gustavo de Oliveira Luiz, PhD |
> Applications/Research Specialist |
> nanoFAB, University of Alberta |
> +1 (780) 619-1463 |
> |
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From dlloyd at laseroptical.co.uk Mon Mar 27 04:27:51 2023 |
From: dlloyd at laseroptical.co.uk (Daniel Lloyd) |
Date: Mon, 27 Mar 2023 08:27:51 +0000 |
Subject: [labnetwork] Strange "sample memory" with LOR 5B |
In-Reply-To: <SA1PR01MB6544ED4A152B84375C04F9D1F3849@SA1PR01MB6544.prod.exchangelabs.com> |
References: <CALPuYFzLg-QX5tPGX7qShke=8o75W=xVb_NB0tUYquFskr4FRg@mail.gmail.com> |
<QB1PR01MB302553713D9C0CCAA388A3139F849@QB1PR01MB3025.CANPRD01.PROD.OUTLOOK.COM> |
<SA1PR01MB6544ED4A152B84375C04F9D1F3849@SA1PR01MB6544.prod.exchangelabs.com> |
Message-ID: <CWLP123MB6543FF7918216F1BA3A45DAAFB8B9@CWLP123MB6543.GBRP123.PROD.OUTLOOK.COM> |
Hi All, |
We?ve seen ghosting before when using the old Shipley SJR series resist. We replaced those with Megaposit SPR and had the same and have since seen it with Microresist Ma-P. Its happened on both silicon and fused silica (SiO2), though is only visible on a bare substrate when we get condensation on it (eg acetone evaporating or from breath). We tried measuring the surface using white light interferometers and not found anything so generally ignored it. This is using pieces for lithography test exposures, not chemical etching them. |
I?d be interested to know where they come from though! |
Daniel Lloyd |
Development Engineer, |
Laser Optical Engineering Ltd. |
Building 72a |
The Air Cargo Centre |
Argosy Road |
East Midlands Airport |
DE74 2SA |
United Kingdom |
Tel: +44 (0) 1332 814612 |
DD: +44(0)1332 815112 |
Mob: +44( 0)7719285200 |
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