INSTRUKCJA DO LABORATORIUM

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1 instrukcja jest dystrybuowana bezpłatnie PIEZORESISTIVE PRESSURE SENSOR Laboratory #4 Updated: 14/12/2014 INSTRUKCJA DO LABORATORIUM ~ 1 ~

2 Aim of the exercise The aim of this exercise is to design a piezoresistive pressure sensor based on a silicon membrane and perform its electro-mechanical simulation. All dimensions are rescaled in order to achieve better convergence. Modeling and simulation 1. Change directory and jobname File Change directory Select working folder File Change jobname Type membr 2. Create a 3-D model of FULL SQUARE membrane with following dimensions: thickness = 5 μm length = 600 μm Preprocessor Modeling Create Volumes Block By Dimensions X1, X2 = 0, 600 Y1, Y2 = 0, 600 Z1, Z2 = 0, 5 3. Define material model Preprocessor Material Props Material Models Select: Structural Linear Elastic Isotropic Type: EX = 130 kpa PRXY = DENSITY = 2330E-18 g/μm 3 4. Define Element for meshing Preprocessor Element Type Add/Edit/Delete Select: Coupled Field 10 NODE 227 Click OK Select Options Choose Analysis Type as Piezoresistive (K1) ~ 2 ~

3 5. Define size control for meshing Select: Plot Lines Preprocessor Meshing Size Ctrl Manual Size Lines Picked Lines Select corresponding lines and enter following values: Horizontal edges (8) o NDIV = 15 o SPACE = -5 Vertical edges (4) o NDIV = 2 o SPACE = leave empty 6. Perform meshing Preprocessor Meshing Mesh Tool Select: Shape = Tet + Free Click Mesh and click Pick All 7. Refine mesh where a piezoresistor will be placed Select: Plot Nodes Pick node with following coordinates: X = 0, Y = 300, Z = 0 (it should be bottom node) Select Entities Select: Nodes, By Location, X coordinates, type 0, From Full and click Apply Select: Nodes, By Location, Y coordinates, type 300, Reselect and click Apply Select: Nodes, By Location, Z coordinates, type 0, Reselect and click OK Select: Plot Nodes Preprocessor Meshing Modify Mesh Refine At Nodes click Pick All. Select: LEVEL = 5 (maximum) and click OK Save the project ~ 3 ~

4 8. Apply following loads Clamping Solution Define Loads Apply Structural Displacement On Areas Select all vertical areas, where the membrane is clamped. Select All DOF and type VALUE = 0 Pressure Solution Define Loads Apply Structural Pressure On Areas Select top horizontal area and type VALUE = 0.1 Pa 9. Define simulation type Solution Analysis Type New Analysis Select: Static 10. Solve Solution Solve Current LS Click OK and wait until the simulation is completed 11. Save database File Save as.. type the file name (membr.db) 12. Checking the solution General Postproc Plot results Contour plot Nodal solution Select: Nodal solution DOF solution Z-component of displacement You should obtain the deflection of your membrane ~ 4 ~

5 1 NODAL SOLUTION STEP=1 SUB =1 TIME=1 UZ (AVG) RSYS=0 DMX = SMN = DEC :01:37 MN Z Y X MX Start new database File Clear & Start new do not read the file File Change jobname Type piezo 14. Create a 3-D model of FULL piezoresistor with following dimensions: length = 30 μm width = 3 μm thickness = 1 μm Preprocessor Modeling Create Volumes Block By Dimensions X1, X2 = 0, 30 Y1, Y2 = 298.5, Z1, Z2 = 0, 1 ~ 5 ~

6 15. Define material model Preprocessor Material Props Material Models Select: Structural Linear Elastic Isotropic Type: EX = 130 kpa PRXY = DENSITY = 2330E-18 g/μm 3 Select: Electromagnetics Resistivity Constant Type: RSVX = 7.8E-8 Ω/m Select: Piezoresistivity Piezoresistive matrix Select piezoresistive stress matrix and fill the table with following values: X-X /Y-Y/Z-Z = 6.5E-5 Pa -1 X-Y/X-Z/Y-X/Z-X/Y-Z/Z-Y = -1.1E-5 Pa -1 XY-XY/YZ-YZ/XZ-XZ = 138.1E-5 Pa Define element for meshing Preprocessor Element Type Add/Edit/Delete Select: Coupled Field 20 NODE 226 Click Apply Select: Structural Mass Solid 20 NODE 186 Click OK Select element 226 and click Options Choose Analysis Type as Piezoresistive (K1) 17. Define size control for meshing Select: Plot Lines Preprocessor Meshing Size Ctrl Manual Size Lines Picked Lines Select corresponding lines and enter following values: Along X-axis (4 the longest lines) NDIV = 15 Along Y-axis (4) NDIV = 5 Along Z-axis (4 the smallest lines) NDIV = 2 ~ 6 ~

7 18. Perform meshing Preprocessor Meshing Mesh Tool Select: Shape = Hex + Mapped Click Mesh and click Pick All 19. Save database File Save as.. type the file name (piezo.db) 20. Apply voltage Solution Define Loads Apply Electric Boundary Voltage On Areas Select one of transversal area and type VOLT = 3 V Solution Define Loads Apply Electric Boundary Voltage On Areas Select second of transversal area and type VOLT = 0 V 21. Define simulation type Solution Analysis Type New Analysis Select: Static 22. Solve Solution Solve Current LS Click OK and wait until the simulation is completed 23. Read current density through piezoresitor General Postproc Plot Results Contour Plot Nodal Solution Select: Nodal solution Conduction current density C. c. d. vector sum General Postproc List Results Nodal Solution Select: Nodal solution Conduction current density C. c. d. vector sum ~ 7 ~

8 Find maximum value. Remember this value! This is the current density for non-stressed piezoresistor. 1 NODAL SOLUTION STEP=1 SUB =1 TIME=1 JCSUM (AVG) RSYS=0 SMN =.128E+07 SMX =.128E+07 DEC :11:10 MN MX 24. Write nodes for sub-modeling Preprocessor Modeling Create Nodes Write Node File Type filename as piezo.node 25. Resume membrane database File Resume from membr.db 26. Read results for the membrane deflection General Postproc Data & File Opts Tick: Read single results file and type: membr.rst Click OK ~ 8 ~

9 27. Setting last set of results General Postproc Read Results Last Set 28. Initiate cut boundary interpolation General Postproc Submodeling Interpolate DOF Select: Fname1 piezo.node, Type: Fname2 piezo.cbdo, Click OK. 29. Resume piezo database File Resume from piezo.db 30. Apply cut boundary DOF Set the marker on the Solution command! Select: File Read input from piezo.cbdo 31. Specify that DOF constraint values are to be accumulated Preprocessor Loads Define Loads Settings Replace vs Add Constraints Select UX, UY and UZ 32. Apply voltage Solution Define Loads Apply Electric Boundary Voltage On Areas Select one of transversal area and type VOLT = 3 V Solution Define Loads Apply Electric Boundary Voltage On Areas Select second of transversal area and type VOLT = 0 V 33. Solve Solution Solve Current LS ~ 9 ~

10 Click OK and wait until the simulation is completed 34. Read current density through piezoresitor General Postproc Plot Results Contour Plot Nodal Solution Select: Nodal solution Conduction current density C. c. d. vector sum General Postproc List Results Nodal Solution Select: Nodal solution Conduction current density C. c. d. vector sum Find maximum value. Compare this value with the previous one. This is the current density for stressed piezoresistor. How does piezoresistor resistance changed? 1 NODAL SOLUTION STEP=1 SUB =1 TIME=1 JCSUM (AVG) RSYS=0 DMX = SMN =.128E+07 SMX =.132E+07 MNMX DEC :58:06.128E E E E E E E E E E+07 END OF LAB #4 ~ 10 ~