Hello Jose,

Is there any particular reason you can't use Cr?

I have only used Ti  (~30nm) as a hard mask for RIE and ICP etching processes. I have found that removing the Ti, even in 50% (vol.) HF can cause issues.

100nm also seems very thick. What etch process are you planning to use? 

Kindest regards,

Jules

Hi Jules,

I wanted to prepare a photomask for UV lithography by myself. When I tried to sputter chromium on square glass substrate and did the mask making procedure, the adhesion of chromium on glass was found to be so poor and all chromium got peeled off. But I found that Ti gives good adhesion to glass and I can etch 100nm Ti in a solution of 5% HF and 5% H2O2 in DI water in less than a min. My worry is that is there any reflection/absorption related issues with Ti while using as masking material.

Laser writer is a kind of mask-less lithography tool. We can make patterns on photoresist using this. If I spin coat photoressit above Ti and pattern it, I can etch Ti and thus I can make a photomask.

Best Regards,

Jose

Your problem is not the adhesion of cromium its the stress in the layers that rips it apart. But honostly i dont get your question. You can use ANY material that block uv-light on a mask. As a matter of fact we use printed foils for structures greather than 40 microns and get pretty good results with them, while the cost 5 euro instead of 400  like silicamasks.

Back to your question, titanium has excelent adhesion propertiers and is generally used for that property, so you should have no problem with it. But as i mentioned before, you can easily use any metal or ceramic that absorbs uv light. As a matter of fact, im sure you can use chromium, too, try a much thinner layer, 100nm is alot in terms of stress and im pretty sure that 30nm block the uv light quite fine.

Oh, i just read that you wanna etch ti with hf and h2o2. Please notice that those also etch the glass substrate! so you either have an excellent timing, or your substrate will be etched, too, which is very undesireable when making a mask.

Hi Tobias,

Even I also want to save the amount that I have to spend on chrome masks since I need to use large number of masks in the coming months and the minimum feature size that I need to achieve is around 20 um only. My plan is to kind of 'replicate' the commercially available photomasks with the facilities available in our laboratory. In that case, I want to use Ti as the masking material on the mask instead of chromium. 

Yeah..I agree that HF based etchants will etch glass very fast. But I am using an etchant that can etch 100nm of Ti in less than 10 sec. Also I am protecting the other side of glass with photoresist. I have made a prototype mask in this way and it looks fairly good. :)

Jose

In that case, there is no problem with your plan on using ti on glass as a self made mask. I would suggest pre-cleaning the glass with an oxigenplasma for 1-2 minute prior to sputtering, that might improve the adhesion.

good luck, maybe post your results for others to learn

You can also use Aluminum... it works well!