SOI Substrate With Altered Glass Layer For Bonding
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Solution Overview
Problem
The manufacturing of SOI substrates using glass substrates often results in deficiency regions due to foreign materials and contamination by movable ions like alkali metal and alkaline earth metal, leading to abnormal semiconductor characteristics and reduced reliability.
Innovation Solution
An altered layer with a higher proportion of silicon oxide and lower density than the glass substrate is formed on the glass substrate surface, using processing solutions like hydrochloric acid or sulfuric acid, to improve bonding and reduce contamination, accompanied by the use of nitrogen-containing layers and insulating layers to prevent ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a glass substrate is used as a base substrate instead of a silicon substrate, then the cost per unit area is reduced and large-sized SOI substrates can be manufactured, but foreign materials on the glass substrate surface cause bonding defects and deficiency regions in the semiconductor layer
Solution Approach 1:
The patent applies preliminary action by forming an altered layer on the glass substrate surface before bonding with the semiconductor substrate. This altered layer, created through chemical modification with hydrofluoric acid or similar treatments, prepares the surface in advance to prevent foreign material contamination and ensure uniform bonding, thereby resolving the contradiction between cost reduction and bonding quality.
2Ease of manufacture
If a glass substrate is used as a base substrate, then cost is reduced, but movable ions such as alkali metal and alkaline earth metal contaminate the semiconductor layer and gate insulating film
Solution Approach 1:
The patent employs an intermediary approach by introducing a barrier layer between the glass substrate and the semiconductor layer. This barrier layer, composed of materials like silicon oxide or silicon nitride, acts as a mediator that blocks the diffusion of movable ions from the glass substrate to the semiconductor layer, thereby preventing contamination while maintaining the cost advantages of using glass substrates.
3Ease of manufacture
If foreign materials exist on the glass substrate surface during bonding, then bonding is not performed at the periphery of foreign materials, but this creates deficiency regions in the semiconductor layer that cause abnormal characteristics
Solution Approach 1:
The patent applies parameter changes by modifying the surface properties of the glass substrate through chemical treatment to alter its bonding characteristics. By changing parameters such as surface energy, roughness, and chemical composition through treatments like hydrofluoric acid etching or plasma processing, the patent ensures uniform bonding across the entire surface, preventing deficiency regions and maintaining reliable semiconductor characteristics.
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 enables the production of SOI substrates with reduced deficiency regions and improved reliability, allowing for the practical use of glass substrates in SOI substrate manufacturing and enhancing the quality of semiconductor devices.
Implementation Method 1
The altered layer is formed on the surface of the glass substrate by processing the glass substrate with a solution including hydrochloric acid, sulfuric acid or nitric acid
Implementation Method 2
hydrogen ions are added to the piece of single crystal silicon, whereby a hydrogen-ion-introduced layer is formed at a predetermined depth of the piece of single crystal silicon
Implementation Method 3
heat treatment is performed, whereby the hydrogen-ion-introduced layer functions as a cleavage plane and then the piece of single crystal silicon to which hydrogen ions are added is thinly separated
Data Source
AI summary
An object is to provide an SOI substrate provided with a semiconductor layer which can be used practically even when a glass substrate is used as a base substrate. Another object is to provide a semiconductor device having high reliability using such an SOI substrate. An altered layer is formed on at least one surface of a glass substrate used as a base substrate of an SOI substrate to form the SOI substrate. The altered layer is formed on at least the one surface of the glass substrate by cleaning the glass substrate with solution including hydrochloric acid, sulfuric acid or nitric acid. The altered layer has a higher proportion of silicon oxide in its composition and a lower density than the glass substrate.