C-Shaped Ring Mechanical Strength via Floating Zone Silicon

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Solution Overview

Problem

Conventional semiconductor wafer fabrication methods, such as the Czochralski crystal growth process, introduce high oxygen content and bulk micro defects into silicon ingots, leading to contamination and reduced mechanical strength of supporting structures like c-shaped rings, which can affect the quality and reliability of larger wafers.

Innovation Solution

Employing the floating zone crystal growth method to produce silicon ingots with low oxygen content, followed by slicing and processing to form c-shaped rings with improved mechanical strength and planarity, which are then used to support semiconductor wafers, thereby reducing contamination and enhancing manufacturing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the Czochralski crystal growth method is used to produce silicon ingots, then the crystal growth process is simpler and more conventional, but the oxygen content and bulk micro defects increase, reducing the mechanical strength and purity of supporting structures

Engineering Contradiction:

Improvecrystal growth process simplicityVSAvoidmechanical strength of supporting structures

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the fundamental parameter of crystal growth method from Czochralski to floating zone technique. This parameter change eliminates the crucible-containing process that introduces oxygen, thereby producing silicon ingots with significantly reduced oxygen content and bulk micro defects, which directly improves the mechanical strength and reliability of supporting structures like c-shaped rings

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The floating zone crystal growth method creates an inert environment by eliminating the need for a crucible that contacts molten silicon. The process occurs in a controlled atmosphere without container material interaction, preventing oxygen contamination from the crucible, thus producing high-purity silicon with enhanced mechanical properties

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of manufacture

If the Czochralski crystal growth method is used, then the production process is more established, but the oxygen content in silicon ingots increases, leading to contamination and reduced planarity of supporting structures

Engineering Contradiction:

Improveestablished production processVSAvoidplanarity of supporting structures

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent transitions from Czochralski to floating zone crystal growth, changing the fundamental processing parameter. This change eliminates oxygen incorporation during crystal formation, resulting in silicon ingots with superior purity that produce supporting structures with enhanced planarity and manufacturing precision, free from oxygen-related defects

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional crystal growth methods are used, then the process is more conventional and easier to implement, but the purity of silicon ingots decreases, affecting the quality of semiconductor wafers

Engineering Contradiction:

Improveease of implementationVSAvoidpurity of silicon ingots

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent implements a parameter change in the crystal growth methodology, adopting the floating zone technique which uses a moving heating zone without crucible contact. This parameter change achieves superior silicon purity by preventing oxygen contamination, directly improving the reliability and quality of semiconductor wafers produced from these high-purity ingots

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

The method results in c-shaped rings with reduced oxygen content and fewer bulk micro defects, providing improved mechanical strength and planarity for supporting larger wafers, enhancing the quality and reliability of semiconductor wafer fabrication processes.

Implementation Method 1

heating the lower portion of the polycrystalline silicon rod beyond the melting point of silicon through eddy currents induced by the RF heating coil

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

placing a radio frequency (RF) heating coil surrounding a lower portion of the polycrystalline silicon rod, heating the lower portion of the polycrystalline silicon rod beyond the melting point of silicon through eddy currents induced by the RF heating coil

Methodology Applied

Scientific EffectRadio frequency heating: Dielectric Heating

Implementation Method 3

solidifying the melt zone on the single-crystal seed layer to form a single-crystal having the same crystalline direction as the single-crystal seed layer

Methodology Applied

Scientific EffectSolidification: Freezing

Implementation Method 4

solidifying the melt zone on the single-crystal seed layer to form a single-crystal

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS10190235B2Wafer supporting structure and method for forming the same

Publication Date: 2019.01.29 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method for forming a wafer supporting structure comprises growing a single crystal using a floating zone crystal growth process, forming a silicon ingot having an oxygen concentration equal to or less than 1 parts-per-million-atomic (ppma), slicing a wafer from the silicon ingot, cutting portions of the wafer to form a supporting structure through a mechanical lathe and applying a high temperature anneal process to the supporting structure.