US 6,961,626 B1 · Dynamic offset and feedback threshold

Abstract

A method, system and medium are provided for enabling improved feedback and feedforward control. An error, or deviation from target result, is observed during manufacture of semi conductor chips. The error within standard deviation is caused by two components: a white noise component and a signal component (such as systematic errors). The white noise component is random noise and therefore is relatively non-controllable. The systematic error, in contrast, may be controlled by changing the control parameters. A ratio between the two components is calculated autoregressively. Based on the ratio and using the observed or measured error, the actual value of the error caused by the signal component is calculated utilizing an autoregressive stochastic sequence. The actual value of the error is then used in determining when and how to change the control parameters. The autoregressive stochastic sequence addresses the issue of real-time control of the effects of run-to-run deviations, and provides a mechanism that can extract white noise from the statistical process variance in real time. This results in an ability to provide tighter control of feedback and feedforward variations.

Claims27

Dependent claims

A computer-implemented method for determining a process threshold for updating a process model in a manufacturing process, comprising the steps of:

(a) inputting a model for a manufacturing process having at least one control parameter that predicts a value for a product characteristic and that sets a process threshold for modifying the model;
(b) receiving an observed value for at least one product and determining a variance between the observed value and the predicted value;
(c) using the variance to calculate a first portion of the variance caused by white noise and a second portion of the variance caused by a systematic variance over the plurality of products;
and
(d) using either the first or second portion of the variance to update the process threshold of the model.

2 more elements

A computer program product for determining a process threshold for updating a process recipe in a manufacturing process for a plurality of products, the computer program product comprising:

(a) at least one computer readable medium, readable by the manufacturing process;
(b) instructions, provided on the at least one computer readable medium, for inputting a model for a manufacturing process having at least one control parameter that predicts a value for a product characteristic and that sets a process threshold for modifying the model;
(c) instructions, provided on the at least one computer readable medium, for receiving at least one observed value for the product and calculating a variance between the observed value and the predicted value;
(d) instructions, provided on the at least one computer readable medium, for using the variance in an auto-regressive stochastic sequence to calculate a first portion of the variance caused by white noise and a second portion of the variance caused by a systematic variance over the plurality of products;
and
(e) instructions, provided on the at least one computer readable medium, for updating the process threshold based upon the first portion of the variance caused by white noise.

3 more elements

Dependencies are inferred from the claim text.

Dynamic offset and feedback threshold

Life of this patent

Dynamic offset and feedback threshold

Life of this patent

Abstract

Claims27