You may want to contact Virginia Semiconductor
Inc for the substrate material.  Call (540) 373-2900.
Also, they are very interested in the same issue.

Stephen Jones


>>
>>  We make microstructures out of 15 mill single crystal silicon substrates.
>> Using 110 oriented silicon and masking along the right 111 plane we can etch
>> vertically or almost completely anisotropically.  A recent application
required
>> etching 60 mill silicon substrates.   The degree of anisotropy we can achieve
>> during etching is inconsistent.  We can rarely get vertical sidewalls while
>> etching.  I am told that this is because of "swirl" in the silicon
substrates.
>> It is my understanding that swirl is a type of "crooked" growth defect during
>> LEC crystal growth processing.
>>
>>
>>  Can anyone verify that the poor anisotropic etching is due to "swirl"?  Is
this
>> a common problem when performing bulk anisotropic etching of silicon
substrates
>> that are > 45 mills thick?  Does anyone know where I can get single crystal
110
>> silicon substrates (~ 0.060 ") with minimal swirl?  Is there another way to
get
>> excellent wet chemistry anisotropic etching without having to worry about
swirl?
>>
>> Any information I can get would be helpful.
>>
>> Thank you,
>>
>> Andrew J. Nielson
>> Graduate Student, Mechanical Engineering
>> Brigham Young University
>> Mems Group
>> email: nielsona@et.byu.edu
>> http://www.et.byu.edu:80/~nielsona
>>
>>