Ceramic Heater Thermocouple Layout for Wafer Temperature Uniformity

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Solution Overview

Problem

Ceramic heaters face challenges in achieving uniform temperature distribution across substrates like silicon wafers, as the temperature-sensing portion of the thermocouple is often located between the heating element and the substrate surface, leading to inadequate temperature control and uniformity.

Innovation Solution

A ceramic heater design featuring a ceramic base member with embedded heating elements and temperature sensors, where at least one temperature sensor's sensing portion is positioned non-overlapping with the heating elements in the up-down direction, allowing for improved temperature control and uniformity by embedding thermocouples within the ceramic base member and using a specific arrangement of heater electrodes and gas flow paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the temperature-sensing portion of the thermocouple is located between the heating element and the substrate surface, then the temperature measurement is simple to implement, but the temperature uniformity of the substrate deteriorates

Engineering Contradiction:

Improveease of temperature sensor installationVSAvoidtemperature uniformity of substrate

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent changes the spatial arrangement of the temperature sensing portion from a position between the heating element and substrate (one-dimensional arrangement) to a position at the side surface of the heating element (moving to another dimension). This dimensional change allows the sensor to measure temperature without interfering with the heat transfer path between the heating element and substrate, thereby improving temperature uniformity while maintaining measurement capability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If the temperature sensor is positioned to improve temperature uniformity (non-overlapping with heating element), then the temperature control accuracy improves, but the device complexity increases

Engineering Contradiction:

Improvetemperature control accuracyVSAvoidcomplexity of sensor and heater arrangement

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the temperature sensing function with the side surface structure of the heating element. By positioning the temperature sensing portion at the side surface rather than requiring a separate installation space between the heating element and substrate, the design integrates multiple functions into a unified structure, reducing overall device complexity while maintaining improved temperature control accuracy.

Inventive Principle:

Principle #5Merging (Combining)

3Temperature

If the thermocouple is embedded within the ceramic base member, then the temperature uniformity across the substrate improves, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvetemperature uniformity across substrateVSAvoidmanufacturing process complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent incorporates the temperature sensing portion into the ceramic base member during the manufacturing process itself, rather than installing it separately after assembly. This preliminary action of embedding the sensor during base member fabrication simplifies the overall manufacturing process by combining multiple steps into one, while achieving the goal of improved temperature uniformity across the substrate.

Inventive Principle:

Principle #10Preliminary 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

This configuration enhances temperature uniformity across the substrate, reducing temperature differences to within 1.6°C, thereby improving the heating process for wafers by effectively controlling the ceramic base member's temperature using non-overlapping thermocouples.

Implementation Method 1

a plurality of heating elements embedded in the ceramic base member

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a plurality of temperature sensors each including a temperature sensing portion embedded in the ceramic base member

Methodology Applied

Scientific EffectThermocouple effect: Thermocouple

Data Source

PatentUS20230380017A1Ceramic heater

Publication Date: 2023.11.23 NITERRA CO LTD

AI summary

There is provided a ceramic heater including: a ceramic base member including: an upper surface and a lower surface opposite to the upper surface in an up-down direction; a plurality of heating elements embedded in the ceramic base member, and a plurality of temperature sensors each including a temperature sensing portion that is embedded in the ceramic base member. The temperature sensing portion of at least one of the plurality of temperature sensors is positioned in a location that does not overlap with the plurality of heating elements in the up-down direction.