Method for manufacturing silicon single crystal wafer and silicon single crystal wafer
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Solution Overview
Problem
Existing silicon single crystal wafers for multilayer structure devices suffer from defects such as slips and dislocation occurrence due to stress during device formation, which are not effectively addressed by existing methods.
Innovation Solution
A method involving a silicon single crystal wafer with an oxygen concentration of 12 ppma or higher, comprising a DZ layer and a BMD layer with specific thickness and density, treated using RTA and BMD-forming heat processes to enhance the device formation region's strength and suppress dislocation extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nitrogen, carbon, and boron are doped at a high concentration to enhance strength and gettering capability, then bulk strength and gettering capability are improved, but oxide precipitates are formed on the surface layer causing electrical characteristic degradation
Solution Approach 1:
The patent applies local quality by creating distinct zones with different impurity concentrations: a DZ layer with low oxygen concentration near the surface and a BMD layer with high boron concentration deeper in the substrate. This spatial differentiation allows the surface region to maintain electrical characteristics while the bulk region provides strength and gettering capability.
Solution Approach 2:
The patent segments the substrate into functionally distinct layers: a surface layer, a DZ layer (denuded zone) with thickness of 0.5-5 μm having low oxygen concentration, and a BMD layer (bulk micro-defect layer) with high boron concentration. This segmentation allows each layer to fulfill its specific function without interfering with others.
2Reliability
If outward diffusion of impurities is promoted by heat treatment to prevent oxide precipitates, then electrical characteristics are improved, but a DZ layer with low oxygen concentration is formed making slips liable to occur due to stress
Solution Approach 1:
The patent changes the concentration parameters of different impurities in different zones: oxygen concentration is reduced in the DZ layer through outward diffusion, while boron concentration is increased in the BMD layer through selective doping. This parameter differentiation allows the DZ layer to provide electrical stability while the BMD layer compensates for mechanical strength.
Solution Approach 2:
The patent creates a composite structure with multiple functional layers: the DZ layer acts as a protective barrier against oxide precipitates, while the BMD layer with high boron concentration provides mechanical strength and slip resistance. The combination of these layers resolves the contradiction between electrical characteristics and mechanical strength.
3Adaptability or versatility
If a multilayer structure device is formed on a single crystal wafer, then device functionality is achieved, but slips occur in device formation regions due to stress received during formation
Solution Approach 1:
The patent applies beforehand cushioning by pre-forming the BMD layer with high boron concentration in the bulk portion before device fabrication. This layer acts as a cushion that absorbs stress and prevents slips during subsequent device formation processes, allowing multilayer structures to be formed without compromising substrate integrity.
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 effectively absorbs defects induced by stress, enhances the strength of the device formation region, and suppresses the occurrence and extension of dislocations in the surface layer, achieving a more precipitous BMD density distribution and improved rosette length reduction.
Implementation Method 1
a DZ layer is formed in the surface layer. This DZ layer has a low oxygen concentration due to the outward diffusion of oxygen
Implementation Method 2
a BMD layer which is positioned immediately below the DZ layer and which has a BMD density of 1×10^11/cm³ or higher
Data Source
AI summary
A method for manufacturing a silicon single crystal wafer for a multilayer structure device including: using a silicon single crystal wafer with oxygen concentration of 12 ppma (JEITA) or higher and composing an NV region; and performing an RTA treatment in a nitrogen-containing atmosphere and a temperature of 1225° C. or higher, a mirror-polish processing treatment, and a BMD-forming heat treatment manufacturing a silicon single crystal wafer having at least a DZ layer with a thickness of 5 to 12.5 μm and a BMD layer positioned immediately below the DZ layer and a BMD density of 1×1011/cm3 or higher from the silicon single crystal wafer surface. During device formation, the silicon wafer surface stress is absorbed immediately below a surface layer, distortion defects are absorbed by the BMD layer, device formation region strength is enhanced, and surface layer dislocation occurrence and extension is suppressed.