Thermocouple RF Filtering for Stable Plasma Electrode Temperature

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Solution Overview

Problem

Substrate processing systems face challenges in accurately controlling the temperature of electrodes in plasma chambers, leading to undesirable effects on substrate processing due to temperature variations and interference from RF and DC signals.

Innovation Solution

The implementation of a circuit with a first filter assembly and a controller, which includes band stop and low pass filters, is used to filter out RF and DC interference from temperature sensor signals, allowing for precise temperature control of the electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If temperature control is implemented in plasma chambers, then substrate processing quality is improved, but RF and DC signal interference degrades measurement precision

Engineering Contradiction:

Improvesubstrate processing qualityVSAvoidtemperature measurement accuracy

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

Filter assemblies are introduced as intermediary components between the thermocouple sensors and the temperature control system. These filters selectively block RF and DC signal paths while allowing the temperature measurement signals to pass through, thereby eliminating the harmful interference without compromising the temperature control functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful RF and DC signal components are extracted and removed from the temperature sensor signals using filter assemblies. The filters are specifically designed to extract only the unwanted frequency components while preserving the legitimate temperature measurement signals

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If filter assemblies are added to remove RF interference, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The filter assemblies are designed to perform multiple functions simultaneously: they block RF signals, block DC signals, and allow temperature measurement signals to pass. This multi-functionality is achieved by combining different filter types (RF filters and DC blockers) into a single integrated assembly, reducing the need for separate components

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Multiple filtering functions are merged into a single filter assembly unit. The RF filter and DC blocker are combined in series to create a compact integrated solution that handles both types of interference without requiring separate installation locations or additional wiring harnesses

Inventive Principle:

Principle #5Merging (Combining)

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

This solution effectively reduces the impact of RF and DC coupling on temperature measurements, enabling more accurate and stable temperature control of electrodes in substrate processing systems, thereby improving substrate quality and processing efficiency.

Implementation Method 1

The first filter is configured to (i) receive a first signal from a first sensor, (ii) prevent passage of a first portion of the first signal, and (iii) output a second signal. The first portion of the first signal is at a first radio frequency.

Methodology Applied

Scientific EffectRadio frequency filtering: Filter (electronic)

Implementation Method 2

A second filter is configured to (i) receive the second signal, and (ii) prevent passage of a portion of the second signal. The portion of the second signal is at a second radio frequency. The second radio frequency is less than the first radio frequency.

Methodology Applied

Scientific EffectRadio frequency filtering: Filter (electronic)

Implementation Method 3

The controller is configured to adjust a temperature of the first electrode based on an output of the second filter.

Methodology Applied

Scientific EffectTemperature control: Feedback

Data Source

PatentUS12283451B2Systems and methods for filtering radio frequencies from a signal of a thermocouple and controlling a temperature of an electrode in a plasma chamber

Publication Date: 2025.04.22 LAM RES CORP

AI summary

A method includes: receiving a first signal from a first sensor at a first filter and preventing passage of a first portion of the first signal via the first filter. The first portion of the first signal is at a first RF. A second portion of the first signal is indicative of a first temperature of a first electrode in a plasma chamber. The method further includes: outputting a second signal from the first filter; receiving the second signal at a second filter; and preventing passage of a portion of the second signal via the second filter. The portion of the second signal is at a second RF. The second RF is less than the first RF. The first filter and the second filter are implemented on a printed circuit board. The method further includes adjusting a temperature of the first electrode based on an output of the second filter.