[labnetwork] Need RIE help

[Mac Hathaway]

Hey all,

This is Mac, at Harvard CNS.  Our STS has shown some symptoms of this 
due to polymer on the walls coming off in the O2 clean, introducing 
fluorine via that route.

When you wrote "the F peak is clipped of in height during the O2 plasma 
clean?"  Did you mean it was still there, but shorter?  This would 
clearly indicate the F is still there, and the only question is where 
it's coming from.

Perhaps a longer chamber clean, with a low-pressure step to spread out 
the cleaning plasma, before the stripping runs?...

Keep in mind that an O2 resist strip can gum up your chamber, and cause 
instability in your regular etch processes if you're not careful.


Mac

Mary Tang wrote:
> Hi Richard --
>
> A similar problem was observed and diagnosed on one of our O2 ashers 
> by one of our industrial labmembers who was a plasma etch engineer at 
> HP.  The cause seems to have been trace amounts Fomblin pump fluid 
> coming back into the chamber -- Fomblin is basically a polymerized 
> freon, so there's your fluorine source.
>
> Mary
>
>
> -- 
> Mary X. Tang, Ph.D.
> Stanford Nanofabrication Facility
> Paul G. Allen Room 136, Mail Code 4070
> Stanford, CA  94305
> (650)723-9980
> mtang at stanford.edu
> http://snf.stanford.edu
>
>
> On 7/27/2011 4:58 AM, Morrison, Richard H., Jr. wrote:
>>
>> Hi Everyone,
>>
>>  
>>
>> Our facility uses an STS RIE tool (100mm wafers), to etch 
>> Nitrides/Oxides/Ti and resist cleans. I have a big problem when we 
>> use O2 to clean off resist from wafers. It seems that just running O2 
>> plasma we etch 1000A/min of SiO2. It should be impossible to etch 
>> SiO2 with O2 plasma.
>>
>>  
>>
>> In trouble shooting we have done the following, change the Teflon 
>> wafer holder, disconnected the SF6, CF4 and CHF3 tanks and capped the 
>> lines, then pumped the machine down and just ran O2 and we still 
>> etched the SiO2 at 1000A/min. We have a plasma scope and the F peak 
>> is clipped of in height during the O2 plasma clean?
>>
>>  
>>
>> Does anybody have any ideas on what may be going on.
>>
>>  
>>
>> Thanks in advance,
>>
>> Rick
>>
>>  
>>
>>  
>>
>>  
>>
>>  
>>
>> Rick Morrison
>>
>> Senior Member Technical  Staff
>>
>> Acting Group Leader Mems Fabrication
>>
>> Draper Laboratory
>>
>> 555 Technology Square
>>
>> Cambridge, MA  02139
>>
>>  
>>
>> 617-258-3420
>>
>>  
>>
>>
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>>     
>
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