SOI Wafer Oxygen Control for Laser Annealing Slip Dislocation
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Solution Overview
Problem
In the manufacturing of semiconductor devices using SOI wafers, extremely-short thermal treatments at high temperatures can generate slip dislocations due to stress at the interface between the support layer and the insulated oxide film layer, leading to plastic deformation and reduced yield ratios.
Innovation Solution
The SOI wafer is designed with a light-scattering defect density of no more than 2×10^8/cm^3 at a depth of 260 µm from the interface, preventing slip dislocation generation during laser annealing at temperatures up to 1200°C for durations of no more than 0.1 seconds by controlling the thermal treatment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser annealing is conducted at high temperature (1200°C or more) for extremely short time (no more than 0.1 seconds), then manufacturing efficiency is improved, but slip dislocation is generated at the interface between support layer and insulated oxide film layer
Solution Approach 1:
The patent applies preliminary action by controlling the oxygen concentration in the support layer before laser annealing. Specifically, the support layer is prepared with an interstitial oxygen concentration of 5×10^18 to 2×10^19 atoms/cm³ through prior crystal growth processes. This preliminary control of material composition prevents slip dislocation generation during the subsequent high-temperature laser annealing process, allowing efficient manufacturing without reliability degradation.
Solution Approach 2:
The patent applies parameter changes by optimizing the interstitial oxygen concentration in the support layer within a specific range (5×10^18 to 2×10^19 atoms/cm³). This parameter control modifies the thermal and mechanical properties of the support layer, enabling it to withstand the thermal stress of laser annealing without generating slip dislocations. The light-scattering defect density is also controlled to no more than 2×10^8, which further prevents dislocation generation during rapid thermal processing.
2Stress or pressure
If oxygen precipitates are present near the interface, then heat conduction is obstructed causing stress concentration, but removing oxygen precipitates may affect material stability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the interstitial oxygen concentration in the support layer within the range of 5×10^18 to 2×10^19 atoms/cm³. This optimized oxygen concentration prevents the formation of oxygen precipitates that would obstruct heat conduction and cause stress concentration, while simultaneously maintaining the material stability and structural integrity of the support layer during laser annealing processes.
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 effectively prevents slip dislocation migration to the surface, maintaining device quality and yield even under extreme thermal conditions, as demonstrated by the low light-scattering defect density and absence of slip dislocations in the examples provided.
Implementation Method 1
laser annealing
Implementation Method 2
heat conduction
Implementation Method 3
light-scattering defect density measured by a 90° light-scattering method
Data Source
Figure 1
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Figure 3
AI summary
An SOI wafer which does not generate slip dislocation even if laser annealing is performed for no more than 0.1 seconds at a maximum temperature of 1200°C or more is provided. This wafer is an SOI wafer used for a process of manufacturing a semiconductor device, in which laser annealing is conducted for no more than 0.1 seconds at a maximum temperature of 1200°C or more, which includes an active layer, a support layer of a monocrystaline silicon, and an insulated oxide film layer between the active layer and the support layer, wherein light-scattering defect density measured by a 90° light scattering method at the depth region of 260 µm toward the support layer side from an interface between the insulated oxide film layer and the support layer is 2×108/cm3 or less.