 Abstract
The present work is concerned with the response of single crystal silicon
to the contact forces during machining processes such single point scribing
and diamond turning operations. The response will be characterized by
the nature of material removal (plastic versus fracture,) the creation
of residual stress, and the presence of indicative phase transformations
in the processed region.
Research Method
Scribing of Si Samples- acts to simulate most basic
of material removal mechanisms
• Characterize material’s response as a function of crystallographic
direction, tool geometry, and applied load using
Raman Spectroscopy- determine presence of HPPT
• Development of model to predict stresses generated within scribe
field from measurement of generated bend distortion
•Use of AFM, SEM and optical microscope observation to give depiction
of surface topography and nature of material removal around scribe
Diamond Turning of Si Wafers- most commonly used high
precision machining method
• Characterize material’s response as a function of crystallographic
direction, rake angle, and feed rate using
• Raman Spectroscopy- determine presence of HPPT in machine surface
• Use of optical microscopy and metrology to determine surface finish
and material removal on surface
• TEM-determine nature of machined chips
Results
Scribing of Si Samples- response of material to scribing
is dependent on geometry and crystallographic direction. Some directions
respond better to one geometry than the other. Sharp cutting constrains
more material resulting in higher residual stress and less debris. Residual
stress seems to be linear dependent to load applied where material is
constrained.
Diamond Turing of Si Wafers- diamond turning yields surfaces
with low RMS. RMS seems to be independent on wafer orientation (only where
pitting doesn’t affect measurements.) Fracture pattern for (100)
seems to be shifted 45o from that seen in previous research3. (110) and
(111) fracture patterns are consistent. Preliminary Raman data shows that
machined surfaces are amorphous.
Supporting Materials
- Annual Report Spring 2004 (PDF, 65Kb)- Outlines experimental and selected
results from scribing work.
- Poster (PowerPoint, 225 Kb)- Presents selected results from both scribing
and diamond turning work.
The following faculty, students and PEC affiliates are involved in this
project:
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