nickel silicide process concern in SNF.

Michael Deal mdeal at
Wed Nov 3 09:38:36 PST 2004

At 09:19 AM 11/3/2004, you wrote:
>Great!  Thanks!  So, are there "official" semiclean B rules now (other 
>than the wet bench concerns?)  Are they ready enough to post to 
>SpecMat?  (And are there any plans for plasma etchers?  I think this is 
>where Jun has concerns...)

    Here's what we decided a month or two ago:

>>Here is the current list of materials planned for the SCT:
>>              Ni, Co, Pt, Al, Hf, Ta, Mo, W, Ti, Cr, Zr
>>All targets except for Pt, Zr, and Cr, are already here.
>>Al, W, and Ti are currently classified as "semi-clean."  The others (Ni, 
>>Co, Pt, Hf, Ta, Mo, and Cr, and Zr) are currently being studied and used 
>>by our users and by industrial chip manufacturers as gate materials and 
>>as silicides.   So far, unlike Au, Cu, alkalai metals, etc., no harmful 
>>effects have been seen on device performance with these 
>>elements.  However, we should still be careful with them in case 
>>something may arise.   In many cases, the users most sensitive to their 
>>effects (i.e. those building CMOS devices) are the ones who are now 
>>studying and using them.  Jim and I are working with several of the 
>>students who are using these materials and we will keep a close eye on this.
>>Here's what we propose:
>>1. Deposition of all metals in the SCT will be limited to 100nm (may be 
>>increased to 200nm).   This will limit the problems (peeling, 
>>contamination, etc.) caused by excess deposition of these materials.
>>2. Al, Ti, and W will be classified as "semi-clean-A" and will be treated 
>>as before in terms of what equipment wafers deposited with these elements 
>>can go into subsequent to their deposition in the SCT. These include LTO 
>>(tylanbpsg), tylanfga, wbsolvent, wbgeneral, wbmetal, wbsilicide as well 
>>as many of the litho and etch equipment.
>>3. The other elements (Ni, Co, Pt, Hf, Ta, Mo, Cr, and Zr) will be 
>>classified as "semi-clean-B."  Wafers deposited with these elements in 
>>the SCT can go into all the equipment listed in the semi-clean group, 
>>EXCEPT for the etching systems.  (Most can only be wet-etched anyway.)
>>Before we do this, however, Jim will look into any issues regarding the 
>>use of wet benches and any possible cross-contamination that might occur 
>>during cleaning.
>>Finally, many of these materials already have some "special processing 
>>rules" such as how any etching solution must be disposed of.  These rules 
>>will be continued.

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