Quartz Heat Treatment Member With Controlled Devitrified Fusion Zones
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Solution Overview
Problem
The challenge in manufacturing semiconductor heat treatment members from quartz glass is the occurrence of devitrification during fusion bonding, which reduces strength and transparency, and existing methods like welding introduce bubbles and strength issues.
Innovation Solution
A semiconductor heat treatment member is formed by fusing quartz glass members with controlled devitrification, where the maximum cross-sectional area of devitrified portions is 1.76 mm2 or less and the area occupancy ratio is 10% or less, and the Al content is between 5 ppm and 25 ppm by weight, to minimize strength reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quartz glass members are connected by heat welding, then assembly is simplified, but bubbles are mixed into welded portions and strength is reduced
Solution Approach 1:
The invention extracts and removes bubbles from the welded portion through a vacuum treatment process. The chamber is evacuated to remove bubbles that were mixed into the welded portions during assembly, thereby restoring strength without requiring a completely different joining method.
Solution Approach 2:
The invention changes the pressure parameter by performing vacuum treatment after welding. By reducing the pressure inside the chamber to 10-6 to 10-9 Pa, the bubbles in the welded portions are removed, significantly improving the strength of the welded portions while maintaining the simplicity of the welding assembly process.
2Strength
If quartz glass members are connected by fusion bonding, then welding bubbles are avoided and strength is maintained, but devitrification occurs in fused portions
Solution Approach 1:
The invention performs preliminary action by controlling the heating rate and holding time during the fusion bonding process. The temperature is increased at a controlled rate of 10-50°C per minute, and the holding time is limited to 1-120 minutes, which prevents excessive devitrification while achieving sufficient fusion bonding strength.
Solution Approach 2:
The invention applies partial action by using low-temperature fusion bonding instead of complete melting. The fusion is performed at a temperature lower than the melting point of quartz glass, which is sufficient to achieve strong bonding while minimizing devitrification. This partial fusion approach balances strength requirements with compositional stability.
3Stability of the object's composition
If low-temperature fusion is used to reduce devitrification, then glass structure stability is improved, but fusion bonding strength may be insufficient
Solution Approach 1:
The invention ensures continuity of useful action by combining low-temperature fusion bonding with subsequent vacuum treatment. The fusion process creates initial bonding, and the continuous vacuum treatment removes any bubbles that form during or after fusion, ensuring both compositional stability and adequate strength are achieved through a continuous multi-step process.
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 approach allows for the use of fused quartz glass members in semiconductor heat treatment while suppressing significant strength decreases due to devitrification, ensuring adequate strength and transparency.
Implementation Method 1
the end portions are connected to each other by heating at a high temperature before melting
Implementation Method 2
The term 'devitrification' means that crystallization proceeds from a metastable glass state and changes to an aggregate of crystal grains grown from a number of crystal nuclei
Data Source
AI summary
A semiconductor heat treatment member includes a plurality of quartz glass members fused to one another, a plurality of devitrified portions are formed in a fused portion at which the quartz glass members are fused, a maximum cross-sectional area of one devitrified portion among the plurality of devitrified portions is 1.76 mm2 or less, and an area occupancy ratio of a total area of the plurality of devitrified portions to an area of a cross section of the fused portion is 10% or less.