Bonded Wafer Reinforcement to Reduce SOI Slip Lines
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Solution Overview
Problem
The manufacturing of silicon-on-insulator (SOI) wafers is hindered by the generation and extension of slip lines, which cause deformation and degrade electrical performance, leading to low yield and product failure.
Innovation Solution
A method involving two thermal reinforcing processes on a bonded wafer, with the first at a lower temperature to strengthen adhesion and a second at a higher temperature to reduce defects, accompanied by an edge grinding process to reduce weight and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single high-temperature thermal reinforcing process is performed on the bonded wafer, then adhesion strength is improved, but thermal stress causes deformation and slip line generation
Solution Approach 1:
The single high-temperature thermal reinforcing process is divided into two separate processes: a first thermal reinforcing process at a lower temperature (first temperature range) and a second thermal reinforcing process at a higher temperature (second temperature range higher than the first). This segmentation allows the adhesion strengthening to be achieved while avoiding excessive thermal stress that would cause deformation and slip line generation in a single high-temperature step.
Solution Approach 2:
The first thermal reinforcing process is performed as a preliminary action before the second thermal reinforcing process. This preliminary low-temperature treatment prepares the bonded wafer by initial adhesion strengthening without inducing severe thermal stress, thereby preventing deformation when the subsequent high-temperature process is applied.
2Strength
If thermal reinforcing process is performed to strengthen adhesion, then bond strength is improved, but defects are generated leading to slip lines
Solution Approach 1:
The thermal reinforcing process is segmented into two distinct temperature stages. The first thermal reinforcing process at the lower first temperature range strengthens adhesion with minimal defect generation, while the second thermal reinforcing process at the higher second temperature range further enhances bond strength without causing severe defects, as the wafer is already prepared from the first treatment.
Solution Approach 2:
The temperature parameter is changed between the two thermal reinforcing processes. The first process uses a temperature in the first temperature range, and the second process uses a temperature in the second temperature range that is higher than the first. This parameter change allows progressive adhesion strengthening while controlling defect generation at each stage.
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
Reduces slip line generation, enhancing the yield of products manufactured from the bonded wafer by preventing delamination and defects.
Implementation Method 1
performing a first thermal reinforcing process on the bonded wafer
Implementation Method 2
performing a second thermal reinforcing process on the bonded wafer at a temperature higher than a temperature at which the first thermal reinforcing process is performed
Implementation Method 3
performing an edge grinding process on an unbonded region along the periphery of the top silicon layer
Data Source
AI summary
The present invention provides a method for reinforcing a bonded wafer, which includes: providing the bonded wafer, which includes a substrate layer, a top silicon layer and an insulating buried oxide layer; performing a first thermal reinforcing process on the bonded wafer; performing an edge grinding process on an unbonded region along the periphery of the top silicon layer; and performing a second thermal reinforcing process on the bonded wafer at a temperature higher than a temperature at which the first thermal reinforcing process is performed.