Run-to-run control utilizing virtual metrology in semiconductor manufacturing

1. An apparatus for performing run-to-run control and sampling optimization in a semiconductor manufacturing process, the apparatus comprising:

at least one control module operative: to determine a process output and corresponding metrology error associated with an actual metrology for a current processing run in the semiconductor manufacturing process; to determine a predicted process output and corresponding prediction error associated with a virtual metrology for the current processing run; to control at least one parameter corresponding to a subsequent processing run as a function of the metrology error and the prediction error; to obtain a prediction model associated with the semiconductor manufacturing process, the prediction model being adapted to predict the process output by estimating at least one processing parameter for the semiconductor manufacturing process; and to perform virtual metrology based on the prediction model, the prediction error being determined as a function of an output of the virtual metrology;

wherein the prediction model comprises a wafer quality prediction model for metrology variable prediction which utilizes tensor input process variables by directly operating on the tensor input process variables.

2. The apparatus of claim 1 , wherein the at least one control module is further operative: to measure at least one target processing parameter corresponding to a wafer fabricated in the current processing run; to compare the measured at least one target processing parameter with an expected value for the at least one target processing parameter; and to determine the metrology error as a function of a variation between the measured at least one target processing parameter and the expected value for the at least one target processing parameter.

3. The apparatus of claim 1 , wherein the prediction model comprises at least one of a single processing chamber based model, a global model across a plurality of processing chambers, a metrology-based prediction model, and a metrology and error-adaptive model.

4. The apparatus of claim 3 , wherein the global model is generated by approximating coefficients corresponding to different processing chambers to a common vector given by prior information on tool capability matching, adding a positive coefficient to balance different terms in the global model, and minimizing the prediction error and optimizing the approximation.

5. The apparatus of claim 4 , wherein the at least one control module is operative to use a block coordinate based algorithm for optimizing the approximation.

6. The apparatus of claim 3 , wherein, in constructing the metrology-based prediction model, the at least one control module is operative: to obtain a plurality of predictors, the predictors comprising information relating to the semiconductor manufacturing process; to decompose the predictors into at least two types, a first type comprising variance profiles, and a second type obtained based on dynamic regression models; and to generate a combined predictor comprising at least a subset of the first type of predictors and at least a subset of the second type of predictors.

7. The apparatus of claim 1 , wherein the at least one control module is further operative: to assign a first weight to the metrology error and a second weight to the prediction error, the first and second weights being indicative of a confidence in the metrology error and prediction error, respectively; and to control the at least one parameter corresponding to a subsequent processing run as a function of the first and second weights.

8. The apparatus of claim 7 , wherein the first and second weights are dynamically adjusted in accordance with a confidence in the metrology error and prediction error, respectively, over time.

9. The apparatus of claim 7 , wherein each of the first and second weights is a percentage, with a sum of the first and second weights being equal to one.

10. The apparatus of claim 7 , wherein the at least one control module is further operative to optimize a sampling policy corresponding to the semiconductor manufacturing process as a function of the first and second weights.

11. The apparatus of claim 7 , wherein respective values of the first and second weights are determined as a function of one or more factors related to uncertainty and chamber matching capabilities associated with the semiconductor manufacturing process.

12. An apparatus for performing run-to-run control and sampling optimization in a semiconductor manufacturing process, the apparatus comprising:

at least one control module operative: to determine a process output and corresponding metrology error associated with an actual metrology for a current processing run in the semiconductor manufacturing process; to determine a predicted process output and corresponding prediction error associated with a virtual metrology for the current processing run; to control at least one parameter corresponding to a subsequent processing run as a function of the metrology error and the prediction error; to assign a first weight to the metrology error and a second weight to the prediction error, the first and second weights being indicative of a confidence in the metrology error and prediction error, respectively; to control the at least one parameter corresponding to a subsequent processing run as a function of the first and second weights; and to optimize a sampling policy corresponding to the semiconductor manufacturing process as a function of the first and second weights;

wherein the at least one control module is further operative to optimize the sampling policy by minimizing a sampling frequency of the semiconductor manufacturing process, the sampling frequency being indicative of at least one of a number of processing runs and a number of wafers between consecutive metrology measurements obtained during actual metrology.

13. An apparatus for performing run-to-run control and sampling optimization in a semiconductor manufacturing process, the apparatus comprising:

at least one control module operative: to determine a process output and corresponding metrology error associated with an actual metrology for a current processing run in the semiconductor manufacturing process; to determine a predicted process output and corresponding prediction error associated with a virtual metrology for the current processing run; to control at least one parameter corresponding to a subsequent processing run as a function of the metrology error and the prediction error; to assign a first weight to the metrology error and a second weight to the prediction error, the first and second weights being indicative of a confidence in the metrology error and prediction error, respectively; to control the at least one parameter corresponding to a subsequent processing run as a function of the first and second weights; and to optimize a sampling policy corresponding to the semiconductor manufacturing process as a function of the first and second weights;

wherein the at least one control module is further operative to optimize the sampling policy by maximizing a time between actual metrology measurements obtained in connection with the semiconductor manufacturing process.

14. An apparatus for performing run-to-run control and sampling optimization in a semiconductor manufacturing process, the apparatus comprising:

at least one control module operative: to determine a process output and corresponding metrology error associated with an actual metrology for a current processing run in the semiconductor manufacturing process; to determine a predicted process output and corresponding prediction error associated with a virtual metrology for the current processing run; to control at least one parameter corresponding to a subsequent processing run as a function of the metrology error and the prediction error; to assign a first weight to the metrology error and a second weight to the prediction error, the first and second weights being indicative of a confidence in the metrology error and prediction error, respectively; and to control the at least one parameter corresponding to a subsequent processing run as a function of the first and second weights;

wherein the at least one control module is further operative to calculate a given one of the first and second weights according to an expression

α

⁡

(

ɛ

)

=

[



ɛ

-

1

T



max

⁡

(



ɛ

-

m

T



)

]

2

,

 where α(ε) represents the given one of the first and second weights, ε −1 T represents a prediction error corresponding to a most recent actual metrology, and max (|ε −m T |)represents maximum absolute prediction error among the last m wafers, m being an integer.

15. A computer program product for performing run-to-run control and sampling optimization in a semiconductor manufacturing process, said computer program product comprising a computer readable storage medium having computer readable program code embodied therewith, said computer readable program code comprising:

computer readable program code configured to determine a process output and corresponding metrology error associated with an actual metrology for a current processing run in the semiconductor manufacturing process;

computer readable program code configured to determine a predicted process output and corresponding prediction error associated with a virtual metrology for the current processing run; computer readable program code configured to control at least one parameter corresponding to a subsequent processing run as a function of the metrology error and the prediction error;

computer readable program code configured to obtain a prediction model associated with the semiconductor manufacturing process, the prediction model being adapted to predict the process output by estimating at least one processing parameter for the semiconductor manufacturing process; and

computer readable program code configured to perform virtual metrology based on the prediction model, the prediction error being determined as a function of an output of the virtual metrology;

wherein the prediction model comprises a wafer quality prediction model for metrology variable prediction which utilizes tensor input process variables by directly operating on the tensor input process variables.