Germanium Cohesion Layer Formation via Multi-Step Oxidation
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Solution Overview
Problem
Conventional germanium condensation processes for substrate manufacturing face challenges with concentration uniformity and surface roughness due to single-temperature oxidation and deposition methods, leading to suboptimal Ge concentration distribution and increased physical and electrical characteristic variations.
Innovation Solution
A substrate manufacturing method involving a multi-step oxidation process at varying temperatures and heat treatment processes to form a germanium cohesion layer with uniform Ge concentration and reduced surface roughness, maintaining the Si-Ge layer in a solid state to prevent mixture state issues, and using a capping silicon layer to control Ge diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If oxidation process is implemented at high temperature (≥1000°C) to achieve sufficient Ge concentration, then Ge concentration reaches 100%, but surface roughness increases and concentration uniformity deteriorates due to liquid state of Si-Ge layer
Solution Approach 1:
The patent applies parameter changes by implementing oxidation at multiple temperature stages rather than a single high temperature. The process uses initial oxidation at moderate temperature (800-900°C) to form SiO2 layer, followed by high temperature oxidation (1000-1100°C) to achieve Ge concentration of 100%, and finally cooling to room temperature for consolidation. This temperature parameter variation allows achieving high Ge concentration while maintaining concentration uniformity and surface roughness within acceptable ranges.
2Reliability
If Si-Ge layer is formed thick to prevent dislocation, then dislocation is reduced, but manufacturing cost increases
Solution Approach 1:
The patent extracts the Ge layer from the Si-Ge structure through selective oxidation. By oxidizing the Si-Ge layer at controlled temperatures, Si atoms are removed as SiO2, leaving behind a consolidated Ge layer with 100% Ge concentration. This extraction process eliminates the need for thick Si-Ge buffering layers, reducing material usage and manufacturing cost while maintaining dislocation reduction through the oxidation-induced Ge consolidation.
3Quantity of substance
If oxidation process is implemented after Si-Ge deposition, then Ge concentration increases, but surface roughness increases due to premature Si oxidation
Solution Approach 1:
The patent applies preliminary action by forming a SiO2 layer through initial oxidation at moderate temperature (800-900°C) before proceeding to high temperature oxidation. This preliminary oxidation step creates a protective SiO2 layer that controls the subsequent oxidation process, preventing premature and uneven Si oxidation that would cause surface roughness. The preliminary action ensures that when high temperature oxidation is applied later, the Ge concentration increases uniformly without excessive surface roughness.
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 method enhances Ge concentration uniformity in the vertical direction and reduces surface roughness, enabling the fabrication of high-concentration GeOI substrates with improved electrical and physical characteristics, such as enhanced effective hole mobility and saturation current in semiconductor devices.
Implementation Method 1
implementing oxidation process at two or more temperatures and heat treatment process at least once during the oxidation process to form a germanium cohesion layer and a silicon dioxide layer
Implementation Method 2
implementing oxidation process at two or more temperatures and heat treatment process at least once during the oxidation process to form a germanium cohesion layer
Data Source
AI summary
The present invention suggests a substrate manufacturing method and a manufacturing method of a semiconductor device comprising: providing a SOI structure having an insulation layer and a silicon layer laminated on a substrate; laminating to form a silicon germanium layer and a capping silicon layer on the SOI structure; implementing oxidation process at two or more temperatures and heat treatment process at least once during the oxidation process to form a germanium cohesion layer and a silicon dioxide layer; and removing the silicon dioxide layer.