-----Original Message-----
From: Shile 
To: lee ki seong ; mems-cc@ISI.EDU

Date: Monday, September 28, 1998 2:47 PM
Subject: Re: A. low stress Si3N4 in PECVD ?


>Lee,
>
>At low excitation frequency PECVD Silicon Nitride films tend to be
>compressive.  Above a few meaghertz the ion peening effect is reduced and
>the films tend to be tensile.  PECVD SiN films can be deposited with
>virtually zero average stress by using dual frequency excitation.  With
this
>approach one alternates between low, e.g. 25-450 KHz and high, e.g. 13.56
>MHz.
>
>At low frequency the compressive stress may be reduced by running at
>ralatively high pressure, however above ~2 Torr the uniformity
deteriorates.
>
>A typical process I have used is 330 sccm SiH4, 2000 sccm NH3, 2 Torr, 380
>degC, 300 watts of RF power at 25-450 KHz.  The stress was ~ 6E9 dynes/cm2
>compressive.  This same process could result in zero average stress with
the
>addition of 13.56 Mhz excitation.
>
>If you don't have access to a dual frequency reactor let me know and I can
>put you in contact with a source for these films.
>
>Roger Shile
>Shile@Endevco.com
>
>
>
>-----Original Message-----
>From: lee ki seong 
>To: MEMS@ISI.EDU 
>Date: Friday, September 25, 1998 7:22 PM
>Subject: A. low stress Si3N4 in PECVD ?
>
>
>>Hi. colleague
>>
>>Is any body know how we can get low stress Si3N4 in PECVD using SiH4, NH3
>>   RF POWER, Temp, Pressure, Vacuum.
>>
>>If some body has a trend to lessen the stress, would you inform me ?
>>
>>with thanks.
>>
>