CVD Tray Tilted Holding Portion Uniform Oxide Film

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Solution Overview

Problem

Conventional trays for CVD methods cause non-uniform thickness distribution of oxide films on silicon wafers due to heat conduction and contact-induced flaws, leading to deteriorated device characteristics and epitaxial wafer flatness.

Innovation Solution

A tray design with a supporting member having a tilted holding portion that is apart from the tray main body, reducing heat conduction and contact area, ensuring uniform oxide film thickness without flaws.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional flat tray is used to support the silicon wafer, then the wafer is stable during film formation, but contact-induced flaws occur on the film-formation-free surface of the wafer

Engineering Contradiction:

Improvewafer stabilityVSAvoidcontact-induced flaws

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts the harmful contact interaction between the tray and the wafer's film-formation-free surface by designing the holding portion to support only the periphery region, thereby eliminating the source of contact-induced flaws while maintaining wafer stability through peripheral support

Inventive Principle:

Principle #2Taking out (Extraction)

2Object-affected harmful factors

If a tray supporting the periphery region is used to prevent contact-induced flaws, then contact-induced flaws are reduced, but non-uniform thickness distribution of oxide film occurs due to heat conduction

Engineering Contradiction:

Improvecontact-induced flawsVSAvoidoxide film thickness uniformity

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention introduces an intermediary material (low thermal conductivity material such as ceramic or plastic) between the tray's holding portion and the silicon wafer's periphery region. This intermediary acts as a thermal barrier that blocks heat conduction from the tray to the wafer, thereby preventing the temperature rise that causes non-uniform oxide film thickness while still providing mechanical support

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the thermal parameter of the contact interface by using materials with low thermal conductivity. This parameter change reduces heat transfer from the tray to the wafer, maintaining uniform temperature distribution across the wafer surface during film formation, which ensures uniform oxide film thickness

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the holding portion is made close to the tray main body for structural simplicity, then manufacturing is easier, but heat conduction from the tray to the wafer increases causing non-uniform film thickness

Engineering Contradiction:

Improvetray structure simplicityVSAvoidoxide film thickness uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention places an intermediary low thermal conductivity material between the tray main body and the holding portion. This intermediary layer blocks the heat conduction path from the heated tray main body to the wafer, preventing temperature rise at the wafer periphery that would cause non-uniform film thickness, while still maintaining structural integrity and ease of assembly

Inventive Principle:

Principle #24Intermediary (Mediator)

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 tray achieves uniform oxide film thickness and prevents contact-induced flaws, enhancing device and epitaxial wafer quality by minimizing heat conduction and maintaining even temperature distribution.

Implementation Method 1

heat conduction from the tray main body to the holding portion is reduced

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

a silicon oxide film as a protective film for preventing auto-doping is formed on the back side of the silicon single-crystal substrate

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS8685855B2Tray for CVD and method for forming film using same

Publication Date: 2014.04.01 SUMCO CORP

AI summary

A tray for film formation by a CVD method includes a tray main body (2) and a supporting member (3) mounted on the tray main body (2) for supporting a silicon wafer (5). The supporting member (3) has a holding portion (3c), on which the silicon wafer (5) is directly placed. The holding portion (3c) has its lower surface (3d) apart from a surface (2a) of the tray main body that is opposed to and apart from the supported silicon wafer (5), whereby the thickness distribution of an oxide film formed on the silicon wafer can be made uniform. The tray has a structure for reducing a contact area between the supporting member (3) and the tray main body (2), with the holding portion (3c) having a tilted surface with its inner circumferential side closer to the tray main body surface (2a) that is opposed to the silicon wafer.