Argon Ion Implantation for Uniform Polysilicon Gettering in SOI Wafers
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Solution Overview
Problem
Existing methods for producing SOI wafers with gettering ability are inefficient and costly due to the inconstancy of polycrystalline silicon layer thickness and the complexity of the CVD method, which affects the mirror polishing process and increases the variation in crystalline interface, leading to variations in the SOI layer thickness.
Innovation Solution
A method involving ion-implantation of argon at a dosage of 1×10^15 atoms/cm² or more on either the base or bond wafer before bonding, with a temperature increase rate of 5°C/minute or higher during bonding heat treatment, forming a polycrystalline silicon layer with uniform thickness and high gettering ability, eliminating the need for CVD and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CVD method is used to form polycrystalline silicon layer, then gettering ability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the CVD (chemical vapor deposition) method with an ion implantation method to form the polycrystalline silicon layer. This substitution eliminates the need for complex CVD equipment and process control, while achieving the same gettering function through a simpler, more cost-effective ion implantation process.
Solution Approach 2:
The patent changes the formation method parameter from CVD to ion implantation, and controls the polycrystalline layer thickness through ion implantation dosage (1×10^15 atoms/cm² or more). This parameter change simplifies the manufacturing process while maintaining the gettering ability.
2Reliability
If CVD method is used to form polycrystalline silicon layer, then gettering ability is improved, but production cost increases
Solution Approach 1:
The patent replaces the CVD method with an ion implantation method to form the polycrystalline silicon layer. This substitution eliminates the need for complex CVD equipment and process control, while achieving the same gettering function through a simpler, more cost-effective ion implantation process.
Solution Approach 2:
The patent uses ion implantation, which is a simpler and more cost-effective method compared to CVD. The ion implantation process requires less expensive equipment and can be performed more easily, reducing overall production costs while achieving the desired polycrystalline silicon layer for gettering.
3Reliability
If polycrystalline silicon layer thickness is increased to improve gettering, then metal impurity capture is improved, but SOI layer thickness variation increases
Solution Approach 1:
The patent controls the polycrystalline silicon layer thickness through ion implantation dosage (1×10^15 atoms/cm² or more). By precisely controlling the ion implantation parameters, the polycrystalline layer thickness is uniformly controlled, achieving effective gettering while maintaining consistent SOI layer thickness across the wafer.
Solution Approach 2:
The patent establishes a controlled process where ion implantation dosage is precisely monitored and adjusted to achieve the desired polycrystalline silicon layer thickness. This feedback control ensures uniform thickness and consistent gettering performance across the entire wafer surface.
4Reliability
If ion implantation dosage is increased to improve polycrystalline layer formation, then gettering ability is improved, but process complexity increases
Solution Approach 1:
The patent optimizes the ion implantation dosage to 1×10^15 atoms/cm² or more, which is sufficient to form a uniform polycrystalline silicon layer with effective gettering ability. This optimized parameter reduces the need for additional process steps or complex process control, simplifying the overall manufacturing process.
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 efficiently produces SOI wafers with a flat, uniform polycrystalline silicon layer that effectively captures metal impurities, enhancing gettering ability while reducing production costs and complexity, and maintaining high productivity.
Implementation Method 1
ion-implantation of argon at a dosage of 1×10^15 atoms/cm² or more on either the base or bond wafer before bonding
Implementation Method 2
a bonding heat treatment is conducted in order to increase bonding strength
Data Source
Figure 1(a)~1(f)
Figure 2(a)~2(b)
Figure 3
AI summary
The present invention relates to a method for producing an SOI wafer, having at least a step of a bonding heat treatment for increasing bonding strength by heat-treating a bonded wafer obtained by bonding a base wafer and a bond wafer, in which argon is ion-implanted from a surface of either the base wafer or the bond wafer at a dosage of 1x1015 atoms/cm2 or more at least before the bonding step, the surface ion-implanted with argon is used as a bonding surface in the bonding step, and an increase rate of temperature to a treatment temperature of the bonding heat treatment is 5°C/minute or higher. Thus the present invention provides a method for producing an SOI wafer facilitating the efficient production of an SOI wafer having in the neighborhood of a buried insulator layer thereof a polycrystalline silicon layer uniform in thickness introduced and having high gettering ability toward metal contaminations in the SOI layer by a simple and low-cost method.