A hard bake is simply a bake after the develop step. It is not the same as a UV bake (which is done in a uv bake tool). The hard bake temp depends on the resist you are using. (for i-line it is about 110-125). Reflow is when you bake over its glass temperature (about 160) and the pac starts to breakdown and the resist "melts". If you UV bake and crosslink the resist you can bake at temps over 160 and still keep the original profile. Robert -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of my2232@columbia.edu Sent: Wednesday, February 25, 2009 1:39 PM To: mems-talk@memsnet.org Subject: [mems-talk] definition of hard bake and hard bake recipes Hello all, I was looking for the definition of "hard bake" to enhance substrate-photoresist interface during wet etch processes. I found that there is no exact definition for that. Some of the users simply keep their developed PRs at elevated temperatures and call this "hard bake" while some other users use "UV-curing tools" to cure their PRs before keeping their PRs at elevated temperatures for extended time, or some others use a convection oven to hard bake their PRs. From here I understand that the definition is not very important as long as the final result is successful... But from my experience, I know that keeping the PR at elevated temperatures is simply called "reflow" but not "hard bake". My question is that: What recipe should I use to enhance my silicon-PR interface for ~90 minutes of BOE (6:1) etch? I am thinking about modifying my mask, but before starting that I want to see what I can do with the example that I have in my hands. This way it will be much cheaper, and if there is a solution, it will definitely be much faster than modifying my masks and doing everything from scratch... I have several PR options, which are: SPR220-3.0, SPR700-1.2L, SPR955-CM 0.9, or SPR955-CM 2.0 Is there somebody who used one of those PRs, and achieved a good adhesion against BOE(6:1) etch for extended etch time (~90 minutes). Best regards, Mehmet Yilmaz Mechanical Engineer