Raising the horns -- and then removing them (Pt etch question)

jim kruger jimkruger at yahoo.com
Thu Jun 17 17:00:35 PDT 2010

You did not say how thick is the Pt.  Stop on what material?

2 approaches: 
 I etch 300 A Pt with a resist mask (about 1.6 um), P=12 mTorr, 80 watts, then clean away sidewalls by acetone  soak for 7 or 10 minutes, then gentle acetone swab with a foam-tip swab from Litho, keep the wafer wet with acetone, flush with acetone, then IPA and blow dry.

2nd approach if it fits your process:  use a thin hard mask of Cr or Ti or PECVD SiO2.  The sidewall deposition is limited to the thickness of the hard mask.

Higher sputtering pressure just makes it worse.


--- On Thu, 6/17/10, Mihir Tendulkar <mihirt at stanford.edu> wrote:

From: Mihir Tendulkar <mihirt at stanford.edu>
Subject: Raising the horns -- and then removing them (Pt etch question)
To: "mrc" <mrc at snf.stanford.edu>
Date: Thursday, June 17, 2010, 3:21 PM

Hi MRC users, 

I've discovered that when I sputter etch Pt in the MRC, using the recipe listed in the logbook, I get substantial redeposition at the corners of my features, resulting in "horns" that short out my devices. 

I am going to try depositing at a higher pressure to get a more isotropic etch and hopefully get rid of these features. Has anyone found a recipe that works well for this purpose? Sidewall sharpness is not critical for me. 

Thanks in advance. 

Mihir Tendulkar
Applied Physics PhD Candidate
Nishi Group, Stanford University

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