Patterning stack optimization
A method of tuning a patterning stack, the method including: defining a function that measures how a parameter representing a physical characteristic pertaining to a pattern transferred into a patterning stack on a substrate is affected by change in a patterning stack variable, the patterning stack variable representing a physical characteristic of a material layer of the patterning stack; varying, by a hardware computer system, the patterning stack variable and evaluating, by the hardware computer system, the function with respect to the varied patterning stack variable, until a termination condition is satisfied; and outputting a value of the patterning stack variable when the termination condition is satisfied.
1. A method of tuning a patterning stack, the method comprising:
defining a function that measures how a parameter representing a physical structural characteristic pertaining to a pattern as structurally transferred into a patterning stack on a substrate is affected by change in a patterning stack variable, the patterning stack variable representing a physical characteristic of a material layer of the patterning stack;
varying, by a hardware computer system, the patterning stack variable and evaluating, by the hardware computer system, the function with respect to the varied patterning stack variable, until a termination condition is satisfied; and
outputting a value of the patterning stack variable when the termination condition is satisfied.
2. The method of claim 1 , wherein the patterning stack variable is one or more selected from: a refractive index of a layer of the patterning stack, an extinction coefficient of a layer of the patterning stack, and/or a thickness of a layer of the patterning stack.
3. The method of claim 1 , wherein the parameter represents one or more selected from: a physical characteristic of a metrology process, a physical characteristic of a lithographic process, and/or a physical characteristic of an etch process.
4. The method of claim 1 , wherein the parameter is one or more selected from: a metrology parameter, a standing wave parameter, a contrast variation parameter, a sidewall angle parameter, a front end critical dimension parameter, a footing parameter, a resist loss parameter, an asymmetry parameter, a back end critical dimension parameter, a pattern placement parameter, a top rounding parameter and/or a litho-etch bias parameter.
5. The method of claim 1 , wherein the function measures how a plurality of parameters each representing a physical characteristic pertaining to the pattern to be transferred into the patterning stack on the substrate is affected by change in the patterning stack variable.
6. The method of claim 5 , wherein the plurality of parameters comprises a physical characteristic of a metrology process.
7. The method of claim 1 , wherein the evaluating the function with respect to the varied patterning stack variable comprises performing a computer simulation to determine a value of the parameter based on the varied patterning stack variable.
8. The method of claim 7 , wherein the parameter comprises a physical characteristic of an etch process and the computer simulation employs an etch model.
9. The method of claim 7 , wherein the parameter comprises a physical characteristic of a metrology process and the computer simulation employs a metrology model.
10. The method of claim 7 , wherein the parameter comprises a physical characteristic of a lithographic process and the computer simulation employs a resist model.
11. The method of claim 1 , wherein the evaluating the function with respect to the varied patterning stack variable comprises determining a value for the parameter based on a pattern profile obtained by measurement or simulation.
12. The method of claim 11 , wherein the pattern profile is either a resist image or an etch image.
13. The method of claim 1 , wherein the evaluating the function with respect to the varied patterning stack variable comprises determining a value for a parameter representing a physical characteristic of a measurement process obtained by measurement or simulation.
14. The method of claim 1 , wherein the function is a cost function and evaluating the function comprising obtaining a value of the patterning stack variable such that the cost function has a value of the parameter at a local extrema or within a preset range around the local extrema value.
15. The method of claim 1 , wherein the parameter is an alignment parameter or a leveling parameter.
16. A non-transitory computer program product comprising machine-readable instructions, that when executed by a processor system, are configured to cause the processor system to at least:
define a function that measures how a parameter representing a physical structural characteristic pertaining to a pattern as structurally transferred into a patterning stack on a substrate is affected by change in a patterning stack variable, the patterning stack variable representing a physical characteristic of a material layer of the patterning stack;
vary the patterning stack variable and evaluate the function with respect to the varied patterning stack variable, until a termination condition is satisfied; and
output a value of the patterning stack variable when the termination condition is satisfied.
17. The computer program product of claim 16 , wherein the patterning stack variable is one or more selected from: a refractive index of a layer of the patterning stack, an extinction coefficient of a layer of the patterning stack, and/or a thickness of a layer of the patterning stack.
18. The computer program product of claim 16 , wherein the parameter represents one or more selected from: a physical characteristic of a metrology process, a physical characteristic of a lithographic process, and/or a physical characteristic of an etch process.
19. The computer program product of claim 16 , wherein the function measures how a plurality of parameters each representing a physical characteristic pertaining to the pattern to be transferred into the patterning stack on the substrate is affected by change in the patterning stack variable.
20. A method comprising:
optimizing, by a hardware computer system, a patterning stack variable, the patterning stack variable representing a physical characteristic of a material layer of a patterning stack on a substrate, with respect to a plurality of parameters each representing a physical structural characteristic pertaining to a pattern as structurally transferred into the patterning stack on the substrate, until a termination condition is satisfied; and
outputting a value of the patterning stack variable when the termination condition is satisfied.
21. A non-transitory computer program product comprising machine-readable instructions, that when executed by a processor system, are configured to cause the processor system to at least:
optimize a patterning stack variable, the patterning stack variable representing a physical structural characteristic of a material layer of a patterning stack on a substrate, with respect to a plurality of parameters each representing a physical characteristic pertaining to a pattern as structurally transferred into the patterning stack on the substrate, until a termination condition is satisfied; and
output a value of the patterning stack variable when the termination condition is satisfied.