Silicon Wafer Surface Oxygen Control for Slip Dislocation Reduction
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Solution Overview
Problem
Silicon wafers used for semiconductor manufacturing face issues with slip dislocations and crystal defects due to oxygen concentration imbalances during heat treatment, where high temperatures in inert gas atmospheres reduce oxygen pinning effects, and oxygen-containing gas treatments lead to ununiform oxygen precipitation nuclei, affecting wafer strength and COP removal.
Innovation Solution
A method involving a rapid thermal process within 1300 to 1380°C for 5 to 60 seconds in an oxygen-containing atmosphere, followed by controlled surface layer removal to eliminate crystal-originated particles and oxygen precipitation nuclei, ensuring uniform oxygen precipitation nuclei distribution in the radial direction, thereby reducing slip dislocations and improving wafer strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RTP is performed in an inert gas atmosphere to reduce COPs, then the surface layer becomes free of crystal-originated particles, but oxygen concentration in the surface layer decreases reducing pinning effect and increasing slip dislocations
Solution Approach 1:
The patent applies preliminary action by performing oxygen introduction into the surface layer before the RTP process. This ensures that sufficient oxygen is present in advance to maintain the pinning effect during subsequent high-temperature treatment, preventing slip dislocations while still enabling COP removal.
Solution Approach 2:
The patent changes the oxygen concentration parameter in the surface layer by introducing additional oxygen through ion implantation or diffusion processes. This parameter modification ensures that even after oxygen loss during RTP, the remaining oxygen concentration is sufficient to prevent slip dislocations.
2Quantity of substance
If heat treatment is performed at temperatures below 1300°C in oxygen-containing gas to increase oxygen concentration, then oxygen is introduced into the surface layer, but oxide films on COPs do not melt and COPs cannot be removed
Solution Approach 1:
The patent performs oxygen introduction as a preliminary step before RTP. This ensures that the surface layer has sufficient oxygen reservoir before undergoing high-temperature treatment, enabling both COP removal and maintenance of oxygen concentration for slip dislocation prevention.
Solution Approach 2:
The patent employs a multi-step periodic process: first introducing oxygen into the surface layer, then performing RTP to remove COPs, and finally conducting additional heat treatment to adjust oxygen distribution. This periodic action sequence achieves both COP removal and oxygen concentration maintenance.
3Manufacturing precision
If heat treatment temperature is increased to 1300°C or higher to melt oxide films on COPs, then COPs can be removed, but oxygen precipitation nuclei are produced in high density in the surface layer
Solution Approach 1:
The patent introduces oxygen into the surface layer before RTP as a preliminary action. This pre-introduced oxygen creates a reservoir that can be consumed during COP removal without depleting the oxygen needed to prevent excessive precipitation nuclei formation, thereby balancing both requirements.
Solution Approach 2:
The patent applies local quality by creating a gradient in oxygen concentration, with higher oxygen content in the surface layer where COPs are located and lower oxygen content deeper in the bulk. This localized oxygen distribution enables effective COP removal while controlling precipitation nuclei formation in specific regions.
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 reduces slip dislocations and crystal defects, ensuring a stronger and defect-free surface for semiconductor devices while maintaining the gettering effect of metal impurities, making the silicon wafer suitable for semiconductor manufacturing.
Implementation Method 1
subjecting a silicon wafer sliced from a silicon single-crystal ingot grown by the Czochralski process to a rapid thermal process in which the silicon wafer is heated to a maximum temperature within a range of 1300 to 1380° C., and kept at the maximum temperature for 5 to 60 seconds
Implementation Method 2
during RTP in an inert gas atmosphere, oxygen in the surface layer of the wafer tends to be dispersed outwardly, so that the oxygen concentration in the surface layer decreases
Implementation Method 3
it is possible to melt oxide films on the inner walls of COPs, thereby removing the COPs
Implementation Method 4
it is possible to melt the oxygen precipitation nuclei produced while crystals are growing
Implementation Method 5
a silicon single-crystal ingot grown by the Czochralski process
Data Source
AI summary
A silicon wafer is manufactured by subjecting a silicon wafer sliced from a silicon single-crystal ingot grown by the Czochralski process to a rapid thermal process in which the silicon wafer is heated to a maximum temperature within a range of 1300 to 1380° C., and kept at the maximum temperature for 5 to 60 seconds; and removing a surface layer of the wafer where a semiconductor device is to be manufactured by a thickness of not less X [μm] which is calculated according to the below equations (1) to (3):X [μm]=a [μm]+b [μm] (1);a [μm]=(0.0031×(said maximum temperature) [° C.]−3.1)×6.4×(cooling rate)−0.4 [° C./second] (2); andb [μm]=a/(solid solubility limit of oxygen) [atoms/cm3]/(oxygen concentration in substrate) [atoms/cm3] (3).