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Simulating stress inside thin films for fabrication process
Posted 20 feb 2015, 13:55 GMT-5 Version 5.0 1 Reply
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Hello,
I am trying to simulate stress that's obtained from a fabrication process.
Initially there's a silicon wafer. It is raised to a temperature of some sort, say 400C for example. Following the rise in temperature, a second layer is deposited on the wafer (comprised of a material m1, let's say), having an initial intrinsic stress from the deposition process. The structure (the initial silicon wafer and the new layer of m1 stacked on top of it) is then cooled back to room temperature.
My current procedure has consisted of the following steps...
I assume the wafer has negligible (zero) stress initially and after it is heated to a temperature at which the subsequent second film is deposited. I use the thermal stress module and solid mechanics module and a stationary study for the simulation. I add another layer (m1) on top of the Silicon wafer in the geometry and set the initial stress and strain in the silicon to be zero and the initial stress in the deposited layer to be equal to the intrinsic stress and the initial strain in the deposited layer to be zero. The initial temperature is the deposition temperature, 400 C, and I set boundary conditions to room temperature. So the simulation (hopefully shows) the stress that is developed from the deposition process resulting from the thermal stress as well as the initial intrinsic stress in m1.
To simulate subsequent layers I extract the average stresses from the simulation. I then follow the same procedure as above. I use the average stresses for my initial conditions and I use the stationary study with boundary conditions set to the deposition temperature of the new layer. After running the simulation I then average the stresses in each of the films and use that as my initial conditions for cooling the structure back to room temperature.
I would like to know if this is the best method to go about trying to do what I'm trying to do, which is to obtain the stresses in the layers after a fabrication process. Is it perhaps possible to have the simulation results automatically be set as the initial conditions of the subsequent process step? And then to add another layer (a new addition to the geometry) with initial intrinsic stress?
Thank you
I am trying to simulate stress that's obtained from a fabrication process.
Initially there's a silicon wafer. It is raised to a temperature of some sort, say 400C for example. Following the rise in temperature, a second layer is deposited on the wafer (comprised of a material m1, let's say), having an initial intrinsic stress from the deposition process. The structure (the initial silicon wafer and the new layer of m1 stacked on top of it) is then cooled back to room temperature.
My current procedure has consisted of the following steps...
I assume the wafer has negligible (zero) stress initially and after it is heated to a temperature at which the subsequent second film is deposited. I use the thermal stress module and solid mechanics module and a stationary study for the simulation. I add another layer (m1) on top of the Silicon wafer in the geometry and set the initial stress and strain in the silicon to be zero and the initial stress in the deposited layer to be equal to the intrinsic stress and the initial strain in the deposited layer to be zero. The initial temperature is the deposition temperature, 400 C, and I set boundary conditions to room temperature. So the simulation (hopefully shows) the stress that is developed from the deposition process resulting from the thermal stress as well as the initial intrinsic stress in m1.
To simulate subsequent layers I extract the average stresses from the simulation. I then follow the same procedure as above. I use the average stresses for my initial conditions and I use the stationary study with boundary conditions set to the deposition temperature of the new layer. After running the simulation I then average the stresses in each of the films and use that as my initial conditions for cooling the structure back to room temperature.
I would like to know if this is the best method to go about trying to do what I'm trying to do, which is to obtain the stresses in the layers after a fabrication process. Is it perhaps possible to have the simulation results automatically be set as the initial conditions of the subsequent process step? And then to add another layer (a new addition to the geometry) with initial intrinsic stress?
Thank you
1 Reply Last Post 20 feb 2015, 13:57 GMT-5
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Posted:
10 years ago
I've attached a file showing the geometry. The films are very thin so it just looks like one cylinder but it's actually comprised of several thin layers on top.
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