Heated Stage Pixel Emissivity Control for Wafer Cooling

Solution Overview

Problem

High temperature processes in wafer processing often result in undesirable thermally induced chemical reactions due to radiative coupling between the wafer and the heated stage, which limits control over wafer cooling rates and temperatures.

Innovation Solution

A heated stage with addressable pixels that can independently adjust their emissivity to control radiative coupling with the wafer, allowing for precise control of wafer cooling rates and temperatures by changing the stage's emissivity and reflectivity across a specific wavelength range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the wafer is heated by a hot heated stage, then the wafer reaches the required process temperature, but the radiative coupling between the wafer and the heated stage couples the wafer cooling rate to that of the heated stage, causing undesirable thermally induced chemical reactions on the wafer film

Engineering Contradiction:

Improvewafer temperature controlVSAvoidthermally induced chemical reactions

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The heated stage incorporates pixels with dynamically adjustable emissivity levels, allowing the stage to transition between high emissivity (for heating) and low emissivity (for rapid cooling) states. This dynamic adjustment decouples the wafer cooling rate from the stage cooling rate, enabling independent control of wafer temperature profiles during cooling phases to prevent thermally induced chemical reactions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of emissivity of the heated stage pixels to control radiative heat transfer. By adjusting emissivity between high and low states, the system modulates the radiative coupling strength between stage and wafer, enabling precise control over heating and cooling rates to eliminate harmful thermal reactions

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the heated stage has high emissivity to efficiently heat the wafer, then heating is effective, but the wafer cooling rate is coupled to the stage cooling rate, limiting control over wafer cooling

Engineering Contradiction:

Improveheating efficiencyVSAvoidwafer cooling rate control

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The heated stage incorporates pixels with dynamically adjustable emissivity levels, allowing the stage to transition between high emissivity (for heating) and low emissivity (for rapid cooling) states. This dynamic adjustment decouples the wafer cooling rate from the stage cooling rate, enabling independent control of wafer temperature profiles during cooling phases to prevent thermally induced chemical reactions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of emissivity of the heated stage pixels to control radiative heat transfer. By adjusting emissivity between high and low states, the system modulates the radiative coupling strength between stage and wafer, enabling precise control over heating and cooling rates to eliminate harmful thermal reactions

Inventive Principle:

Principle #35Parameter changes

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

Enables rapid and controlled wafer heating or cooling, preventing undesirable chemical reactions by decoupling the wafer from the heated stage, allowing for precise temperature control and reducing thermally induced chemical reactions.

Implementation Method 1

the radiative coupling between the wafer and the heated stage couples the wafer cooling rate to that of the heated stage

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

reducing the heating stage coupling to a predetermined minimum value and reducing the heated stage temperature

Methodology Applied

Scientific EffectRadiative coupling: Thermal Radiation

Data Source

PatentUS10256121B2Heated stage with variable thermal emissivity method and apparatus

Publication Date: 2019.04.09 TOKYO ELECTRON LTD

AI summary

Embodiments include a method for controlled cooling of a heated stage. The method includes setting a stage coupling to a maximum value and heating the stage to a process temperature. The method includes providing a wafer on the heated stage in a process chamber. The method includes performing a process on the wafer and reducing the heating stage coupling to a predetermined minimum value and reducing the heated stage temperature. The method includes removing the wafer from the heated stage and the process chamber. The heated stage is covered with a plurality of pixels, each pixel of the plurality of pixels include a level of emissivity and are equipped with an emissivity control device configured to independently adjust the level of emissivity of the pixel. The heated stage coupling is configured to achieve a predetermined radiative coupling and control the wafer cooling rate and target temperature.