using the epi machine to get smooth sidewalls

saraswat saraswat at
Thu Jun 2 11:12:03 PDT 2005

Hi All,

The epi machine is a very delicate piece of equipment, very old and 
very expensive to maintain. A large number of students use it for 
depositing ultrathin layers Si, SiGe and Ge for fabricating 
nanodevices. The heteroepitaxial growth of Ge or SiGe on Si depends 
critically on fine tuning of the reactor. A slight change in the 
reactor parameters totally throws off the quality of the grown layers.

I fully agree with Tom Kenny that it will be foolish idea to use this 
reactor to smooth out the STS etch profiles.

Krishna Saraswat
On Jun 2, 2005, at 10:02 AM, Thomas Kenny wrote:

> All -
> I am concerned about this line of discussion.  The epi machine in CIS 
> has been very fragile, expensive to maintain, and is the focal point 
> of many research projects in several groups because of its 
> capabilities for deposition.
> The fact that it can also be used as a high-temperature H2 annealing 
> station is not itself a good reason to let it be used as such.  I 
> believe this would be a little like using the e-beam system to remove 
> edge bead on some of our wafers, or using the aligner/bonder to 
> assemble plastic parts from the student shops.  these things are 
> possible, but they are also very bad ideas.
> If there is a serious interest in a H2 annealing process for STS 
> sidewall smoothing, we should prepare a dedicated furnace tube for 
> that process.  I think this would be a very popular capability.
> Otherwise, I strongly oppose the concept of using the epi as a 
> generic, lab-wide tool to smooth STS sidewalls.  the costs of the 
> repairs to the epi after just a few months of such use would far 
> exceed the cost of making a dedicated H2 annealing process in a 
> furnace tube.
> tk

On Jun 2, 2005, at 9:07 AM, Wibool Piyawattanametha wrote:

> Hi Kevin,
> Please find this paper.  The answer is there.
> Ming-Chang M. Lee and Ming C. Wu, "3D Silicon Transformation using 
> Hydrogen
> Annealing," Proc. Solid State Sensor, Actuator and Microsystems 
> Workshop
> (Hilton Head 2004) Hilton Head Island, South Carolina, June 6-10, 2004.
> Best,
> WP
> Wibool Piyawattanametha, Ph.D.
> Stanford University
> Departments of Applied Physics, Biological Sciences, and Pediatrics
> James H. Clark Center (Bio-X) - Room W080
> 318 Campus Drive
> Stanford, CA 94305
> Telephone: (650) 725-4097
> Fax: (650) 724-5805
> -----Original Message-----
> From: Kevin Huang [mailto:kevhuang at]
> Sent: Thursday, June 02, 2005 8:27 AM
> To: labmembers at
> Subject: using the epi machine to get smooth sidewalls
> Hi,
>       I've heard that people use the epi machine to get smooth side 
> walls
> after an STS Etch run.  Does anyone have any experience doing this and 
> if
> so, what's the recipe you used?
> Thanks.
> Kevin

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