AW: [mems-talk] Anneal recipe for Pt thin film on Si wafer

[Miyakawa, Natsuki]

Hi Michael,

300nm of thermal SiO2 is reported to be a good diffusion barrier and to prevent silicide formation even at temperatures as high as 1000°C. Actually, Pt films (evaporated & sputtered) adhere on thermal SiO2 without any adhesion layer and it survives also high-temperature annealing. Metallic adhasion layers such as Ti or Cr rather cause problem at high temperatures due to diffusion of adhesion layer itself which results in degraded adhesion and drift of electric resistance of Pt. I have read that metal oxide layers such as Al2O3 should work as a good adhesion layer & diffusion barrier in one.

See e.g.

"High temperature materials for thin-film thermocouples on silicon wafers", K.G. Kreider, G.Gillen, Thin Solid Films 376 (2000) 32-37

"Adhesion layer for platinum based sensors", Robert G et al., US patent no 4952904


Regards,

Natsuki
 

-----Ursprüngliche Nachricht-----
Von: mems-talk-bounces at memsnet.org [mailto:mems-talk-bounces at memsnet.org] Im Auftrag von Michael D Martin
Gesendet: Mittwoch, 5. März 2008 15:58
An: General MEMS discussion
Betreff: Re: [mems-talk] Anneal recipe for Pt thin film on Si wafer

I've had this problem in the past, i.e. formation of Pt-Si alloys during an anneal with (I think) a Cr adhesion layer.  Could anyone recommend a material stack Pt/ adhesion layer/ diffusion barrier?  

Thanks, 
   Michael 
   U. of Louisville 

>>> Oliver Horn <o.horn at tuhh.de> 3/3/2008 4:38 AM >>>
Hello Natsuki,

you will get PtSi or PtSi2 if you heat up Pt on Si without diffusion 
barrier, even at 260&#176;C.  The adhesion is only a bit improved.

Oliver