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Stress Analysis after annealing

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hi,I am a newcomer

I am doing a project .I need to anneal a silicon wafer first.
then how can I analyse the internal stress of the silicon wafer by comsol?

Thanks very much

Chang

6 Replies Last Post 20 apr 2015, 04:26 GMT-4

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Posted: 10 years ago 19 apr 2015, 18:27 GMT-4
How does annealing affect the stress of a Si wafer? Is there an oxide layer formed? There needs to be some sort of structural change otherwise the wafer will elastically return to its original state when cooled.
How does annealing affect the stress of a Si wafer? Is there an oxide layer formed? There needs to be some sort of structural change otherwise the wafer will elastically return to its original state when cooled.

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Posted: 10 years ago 19 apr 2015, 22:24 GMT-4
sorry,it's my fault
actually the structure of the wafer is Au-alumina-Si
the thickness of the Au film is 50-100nm,
and I need to analyse the internal stress of the Au film after annealing

thanks for your reply
sorry,it's my fault actually the structure of the wafer is Au-alumina-Si the thickness of the Au film is 50-100nm, and I need to analyse the internal stress of the Au film after annealing thanks for your reply

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Posted: 10 years ago 19 apr 2015, 22:38 GMT-4
So the crystalline structure changes at temperature, for example grain growth in the gold resulting in tensile strain, then when it's cooled there's an additional stain from thermal mismatch? Or maybe there's viscoelastic flow in the Au layer which results in stress reduction at the anneal temperature which is then adjusted by thermal expansion mismatch? If so there I can't help you because I'm completely ignorant of any state change modeling in Comsol (I'm just learning how to use it myself). But maybe the support guys can help. I think the simplest approach would be to somehow set the stress state of the film (which would be biaxial if it's a planar film) at the critical temperature then reduce the temperature from there with the material then treated as a solid.
So the crystalline structure changes at temperature, for example grain growth in the gold resulting in tensile strain, then when it's cooled there's an additional stain from thermal mismatch? Or maybe there's viscoelastic flow in the Au layer which results in stress reduction at the anneal temperature which is then adjusted by thermal expansion mismatch? If so there I can't help you because I'm completely ignorant of any state change modeling in Comsol (I'm just learning how to use it myself). But maybe the support guys can help. I think the simplest approach would be to somehow set the stress state of the film (which would be biaxial if it's a planar film) at the critical temperature then reduce the temperature from there with the material then treated as a solid.

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Posted: 10 years ago 19 apr 2015, 22:57 GMT-4
appreciate for your reply anyway
appreciate for your reply anyway

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 10 years ago 20 apr 2015, 02:10 GMT-4
Hi

there should be a Model library example of thermal stress from a bi-domain structure, and how to continue a study from the initial stress build-up. If I remember right define the geometry at the "hot" temperature, set the stress free Temperature to the "hot temperature", let cool down. then start a new study from the deformed/stressed cooled down state.

If you want to structure one layer, draw the structures and then turn the Young modulus down to "zero" via a variable and you will get the results, at best for a structured, pre-stressed system

--
Good luck
Ivar
Hi there should be a Model library example of thermal stress from a bi-domain structure, and how to continue a study from the initial stress build-up. If I remember right define the geometry at the "hot" temperature, set the stress free Temperature to the "hot temperature", let cool down. then start a new study from the deformed/stressed cooled down state. If you want to structure one layer, draw the structures and then turn the Young modulus down to "zero" via a variable and you will get the results, at best for a structured, pre-stressed system -- Good luck Ivar

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Posted: 10 years ago 20 apr 2015, 04:26 GMT-4
thanks

should the initial temperature be the annealing temperature?or the atmospheric temperature?
thanks should the initial temperature be the annealing temperature?or the atmospheric temperature?

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