Wafer Heat Treatment Airflow Layout for Stagnation Suppression

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Solution Overview

Problem

Conventional heating treatment apparatuses for semiconductor wafers experience airflow stagnation, leading to sublimated matter leakage and increased energy consumption due to the center-oriented descending airflow and limited exhaust rate.

Innovation Solution

The apparatus features a dual gas inlet system where the first gas inlet is at the same height as the substrate and the second gas inlet is higher, with a larger flow rate from the first inlet to create a horizontal laminar flow and suppress airflow stagnation, allowing for a smaller exhaust rate while preventing sublimated matter leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a center-oriented descending airflow is created by introducing downflow from above the processing space, then the wafer temperature uniformity is improved, but airflow stagnation is generated between the descending airflow and the shutter member inner wall

Engineering Contradiction:

Improvewafer temperature uniformityVSAvoidairflow stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The gas inlet is divided into two separate inlets: a first gas inlet positioned at the same height as the wafer and a second gas inlet positioned higher than the first gas inlet. This segmentation allows independent control of airflow patterns to achieve both wafer temperature uniformity and prevent airflow stagnation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the processing space are provided with different airflow characteristics. The first gas inlet provides horizontal laminar flow at wafer level for uniform heating, while the second gas inlet provides downward flow from above to prevent stagnation in the upper region near the shutter member.

Inventive Principle:

Principle #3Local quality

2Reliability

If the exhaust rate is increased to suppress sublimated matter leakage, then the sublimated matter leakage is reduced, but energy consumption is increased

Engineering Contradiction:

Improvesublimated matter containmentVSAvoidexhaust energy

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Gas is supplied from the first and second gas inlets before and during the heating process to establish a controlled airflow pattern that prevents sublimated matter from reaching the shutter member inner wall where stagnation would occur. This preliminary action eliminates the need for high exhaust rates.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The downflow from the second gas inlet, which could potentially cause cooling of the wafer, is used beneficially to prevent airflow stagnation and sublimated matter accumulation. By controlling the flow rate to be smaller than the first gas inlet, it prevents stagnation without excessive cooling.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Manufacturing precision

If gas is supplied at a large flow rate from the first gas inlet at wafer level, then horizontal laminar flow is created for uniform heating, but the exhaust load increases

Engineering Contradiction:

Improvefilm thickness uniformityVSAvoidgas flow rate

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The airflow from the first gas inlet (horizontal laminar flow) and the second gas inlet (downward flow) are merged to create a comprehensive airflow pattern that achieves both uniform wafer heating and prevention of airflow stagnation, while the combined exhaust load is managed through the central exhaust unit.

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 configuration effectively reduces airflow stagnation and sublimated matter leakage, achieving energy savings by lowering the required exhaust rate and improving film thickness uniformity during the heating treatment process.

Implementation Method 1

supply a horizontal laminar flow toward a surface of the substrate on the placing table

Methodology Applied

Scientific EffectLaminar flow: Laminar Flow

Implementation Method 2

suppress generation of stagnation of an airflow within a processing space

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

heat the substrate uniformly as it affects uniformity of a film thickness

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11842906B2Heating treatment apparatus and heating treatment method

Publication Date: 2023.12.12 TOKYO ELECTRON LTD

AI summary

A side surface unit of a heat treatment space S is formed by a shutter member 250 including an outer shutter 260 and an inner shutter 270. Supply air A is supplied as a horizontal laminar flow toward a wafer W from a lower end side of the shutter member 250, that is, from a gap d1 located on the level with the wafer W placed on a heat plate 211 of a mounting table 210. Supply air B is supplied into the heat treatment space S from an upper end side of the shutter member 250, that is, from a gap d2 positioned higher than the wafer W. A ratio between a flow rate of the supply air A and a flow rate of the supply air B is 4:1.