Endpoint Sensor Control for Edge Ring Erosion Compensation

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Solution Overview

Problem

Substrate processing systems face challenges in maintaining etch rate uniformity due to erosion of edge rings, leading to non-uniform etching and tilt angles, which are difficult to compensate for with traditional metrology processes that are time-consuming and not substrate-specific.

Innovation Solution

A substrate processing system with a model generation module that uses time traces from endpoint sensors to create conversion models for predicting erosion compensation setpoints, allowing for real-time adjustment of edge ring heights or RF voltages to maintain uniformity without periodic metrology processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional metrology processes are used to compensate for edge ring erosion, then etch rate uniformity can be maintained, but the process is time-consuming and not substrate-specific

Engineering Contradiction:

Improveetch rate uniformityVSAvoidmetrology process time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs preliminary characterization of edge ring erosion by analyzing endpoint sensor data from previous substrates. A conversion model is generated in advance that correlates endpoint sensor signals with actual etch rate uniformity measurements. This preliminary model allows real-time compensation without performing time-consuming metrology processes on each substrate.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback loop where endpoint sensor data from each substrate is fed into the conversion model, which then predicts the current edge ring erosion state. Based on this prediction, the system automatically adjusts process parameters for the next substrate to compensate for erosion, creating a continuous feedback mechanism that maintains etch uniformity without periodic metrology interruptions.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If periodic metrology processes are performed to measure etch uniformity, then erosion compensation can be achieved, but processing efficiency decreases due to frequent interruptions

Engineering Contradiction:

Improveetch uniformity measurementVSAvoidprocessing efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system uses the endpoint sensor data that is already being collected during normal substrate processing to self-characterize the edge ring erosion state. Instead of requiring separate metrology processes, the system extracts useful information from the endpoint detection signals themselves, allowing it to self-adjust and maintain etch uniformity without external measurement interventions.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system replaces physical metrology measurement processes with a computational approach. A conversion model translates endpoint sensor signals into predictions of etch rate uniformity and edge ring erosion state. This substitution of mechanical measurement with computational analysis eliminates the need for time-consuming periodic metrology while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If edge ring erosion is not compensated, then processing is faster, but etch rate uniformity deteriorates leading to non-uniform etching and tilt angles

Engineering Contradiction:

Improveprocessing speedVSAvoidetch rate uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system implements dynamic adjustment of process parameters based on the current edge ring erosion state. Instead of using static compensation values, the conversion model continuously predicts the erosion state from endpoint sensor data and adjusts process parameters in real-time. This dynamic approach maintains etch uniformity throughout the edge ring's operational life without requiring shutdowns for compensation.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10903050B2Endpoint sensor based control including adjustment of an edge ring parameter for each substrate processed to maintain etch rate uniformity

Publication Date: 2021.01.26 LAM RES CORP

AI summary

A substrate processing system includes model generation and setpoint modules. The model generation module receives a first time trace based on an output of an endpoint sensor and obtains a target setpoint. A portion of the first time trace is indicative of an endpoint at which a feature has been created in a first substrate. The target setpoint is generated based on a metrology process and is used to compensate for erosion of a first edge ring. The model generation module generates a conversion model based on the portion and the target setpoint. The setpoint module: based on the output, receives a second time trace that is generated subsequent to generation of the first time trace; and based on the conversion model, converts the second time trace to a predicted erosion compensation setpoint, which is set while processing a second substrate using the first or a second edge ring.