High-TCR Heater Control with Selective Resistance Signal Filtering

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Solution Overview

Problem

Substrate processing systems face challenges in accurately controlling temperature due to limited temperature sensors and system noise, leading to inaccurate resistance and temperature calculations, especially in multi-zone substrate supports where structural variations cause spurious resistance changes.

Innovation Solution

A controller system that calculates resistance and temperature of heater elements using voltage and current measurements, and employs a filter module to differentiate between noise and actual temperature changes, applying resistance offsets to ensure accurate temperature control across zones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If resistance-based temperature calculation is used in multi-zone substrate supports, then temperature control capability is improved, but structural variations cause spurious resistance changes that reduce measurement precision

Engineering Contradiction:

Improvetemperature control capabilityVSAvoidtemperature calculation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system continuously monitors resistance changes in heater elements and uses feedback control to distinguish between resistance changes caused by temperature variations and those caused by structural variations. The controller compares expected resistance changes (based on temperature control commands) with actual resistance changes, and only processes temperature control signals when the discrepancy falls within a predetermined threshold, thereby maintaining measurement precision while enabling temperature control capability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary verification mechanism that acts as a mediator between resistance measurement and temperature calculation. Instead of directly converting resistance changes to temperature changes, the system uses an intermediate comparison step that references expected resistance behavior. This intermediary process filters out spurious resistance changes from structural variations before they affect temperature calculations, resolving the contradiction between enabling temperature control and maintaining measurement accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If filtering is applied to resistance signals to remove noise, then temperature calculation accuracy is improved, but response time to actual temperature changes may increase

Engineering Contradiction:

Improvetemperature calculation accuracyVSAvoidresponse time

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The filtering mechanism is made dynamic rather than static. The system adjusts the filtering threshold based on the operational context and expected temperature changes. When rapid temperature changes are anticipated or detected, the filtering threshold is temporarily relaxed to allow faster response. When the system is in a stable state, stricter filtering is applied to remove noise. This dynamic adjustment resolves the contradiction between filtering noise and maintaining fast response time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs periodic verification of resistance changes against expected values. Instead of continuous heavy filtering that would slow response, the system periodically checks whether resistance changes align with expected temperature control behavior. This periodic verification approach maintains measurement precision by filtering out anomalies while preserving fast response to genuine temperature changes, as the filtering is applied selectively rather than continuously.

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system provides precise temperature control across different zones of a substrate support, filtering out noise and structural variations to maintain accurate temperature calculations and control, enhancing the reliability of substrate processing.

Implementation Method 1

A resistance calculation module to calculate a first resistance of a first heater element of a plurality of heater elements of the first substrate support

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a temperature calculation module to calculate a first temperature of the first heater element based on the calculated first resistance

Methodology Applied

Scientific EffectTemperature coefficient of resistance: Thermo-resistive Effect

Implementation Method 3

a filter module to filter a first signal that corresponds to the calculated first resistance

Methodology Applied

Scientific EffectSignal filtering: Filter (electronic)

Data Source

PatentUS20240203763A1Use of signal filtering schemes in high TCR based control

Publication Date: 2024.06.20 LAM RES CORP

AI summary

A controller to control a temperature of a first substrate support in a substrate processing system includes a resistance calculation module to calculate a first resistance of a first heater element of a plurality of heater elements of the first substrate support, a temperature calculation module to calculate a first temperature of the first heater element based on the calculated first resistance, and a filter module to filter a first signal that corresponds to the calculated first resistance. The temperature calculation module selectively causes the filter module to filter the first signal in response to a determination of whether at least one condition associated with operation of the substrate processing system is met.