Feedforward Process Control for Semiconductor Misregistration

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Solution Overview

Problem

Current methods for measuring misregistration in semiconductor device manufacturing are inefficient, as they typically require slow and inaccurate metrology on nominal wafers, leading to delayed and ineffective process adjustments within the same lot or batch.

Innovation Solution

The method involves generating Design of Experiment (DOE) wafers with varied parameters to rapidly and accurately measure misregistration, using a metrology tool to generate correctables that are then applied in real-time to adjust the processing tool's parameters, enabling feedforward control across lots and batches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional metrology methods are used on nominal wafers, then measurement simplicity is maintained, but measurement precision and speed deteriorate

Engineering Contradiction:

Improvemisregistration measurement accuracyVSAvoidmetrology system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

DOE wafers are prepared in advance with pre-defined target patterns and structures that are specifically designed for misregistration measurement. The wafers contain multiple target types (e.g., alignment marks, test patterns) at known positions and orientations, enabling direct and accurate measurement without requiring complex measurement setups during the actual measurement process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent varies multiple parameters across the DOE wafer including target positions, orientations, sizes, and types to create a comprehensive test structure. By encoding different measurement scenarios into the physical structure of the DOE wafer itself, the system achieves high measurement precision through structural design rather than through complex measurement equipment or procedures

Inventive Principle:

Principle #35Parameter changes

2Productivity

If metrology is performed on nominal wafers, then process simplicity is maintained, but productivity deteriorates due to slow measurement speed

Engineering Contradiction:

Improvelot throughputVSAvoidtime for metrology and process adjustment

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system performs metrology on DOE wafers continuously during the manufacturing process rather than as a separate batch operation. By integrating DOE wafer measurement into the regular production flow, the system maintains continuous manufacturing operations while simultaneously gathering measurement data, thereby eliminating idle time and improving overall productivity

Inventive Principle:

Principle #20Continuity of useful action

3Manufacturing precision

If conventional metrology and feedback methods are used, then process control simplicity is maintained, but manufacturing precision deteriorates due to delayed adjustments

Engineering Contradiction:

Improvemisregistration controlVSAvoiddelay in process adjustment

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The system implements a closed-loop feedback mechanism where misregistration measurements from DOE wafers are immediately fed back to adjust subsequent processing parameters. The feedback loop includes real-time data processing, correctable generation, and automated parameter adjustment, enabling the system to continuously optimize manufacturing precision based on actual measurement results without manual intervention or delays

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Inventive Principle:

Principle #10Preliminary action

4Manufacturing precision

If feedforward control is implemented using DOE wafers, then manufacturing precision improves through real-time adjustments, but device complexity increases

Engineering Contradiction:

Improveprocess control accuracyVSAvoidprocess control system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary layer consisting of DOE wafers that mediate between the manufacturing process and the control system. These wafers serve as physical carriers that encode process variation information in their target structures, translating complex process deviations into measurable physical quantities that can be easily processed by the control system, thereby simplifying the overall control architecture

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11635682B2Systems and methods for feedforward process control in the manufacture of semiconductor devices

Publication Date: 2023.04.25 KLA CORP

AI summary

A method for process control in the manufacture of semiconductor devices including performing metrology on at least one Design of Experiment (DOE) semiconductor wafer included in a lot of semiconductor wafers, the lot forming part of a batch of semiconductor wafer lots, generating, based on the metrology, one or more correctables to a process used to manufacture the lot of semiconductor wafers and adjusting, based on the correctables, the process performed on at least one of; other semiconductor wafers included in the lot of semi-conductor wafers, and other lots of semiconductor wafers included in the batch.