Wafer Separation via Localized Edge Stress Induction
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Solution Overview
Problem
Current methods for producing wafers result in significant material loss due to random break initiation and location, leading to uneven wafer thickness and undesirable oscillations during the break propagation process, which complicates the production of high-quality wafers with minimal material consumption.
Innovation Solution
A method involving the introduction of defined local stress peaks in the peripheral region of the workpiece to control the initiation point and time of the break, using techniques such as thermal expansion, mechanical stress, and external forces to induce precise stress distributions, allowing for controlled separation of wafers with improved thickness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If random break initiation is used in conventional wafer separation methods, then the breaking process is simpler to initiate, but the wafer thickness uniformity deteriorates and material loss increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the break initiation point through localized stress induction at the wafer edge before the actual breaking process. This is achieved by applying thermal stress or mechanical force to a specific region, creating a controlled starting point for the break that propagates through the wafer, thereby ensuring uniform thickness while maintaining process simplicity
Solution Approach 2:
The patent implements local quality by concentrating stress induction in a specific localized region (edge or peripheral area) of the wafer rather than applying uniform stress across the entire wafer. This localized stress application creates a controlled break initiation point while preserving the integrity and uniformity of the remaining wafer structure
2Loss of substance
If random break location is used in conventional methods, then the breaking process requires less control, but material loss and handling difficulty increase
Solution Approach 1:
The patent uses preliminary action to pre-determine the break location at the wafer edge or peripheral region before breaking occurs. This controlled positioning ensures that the break propagates through the entire wafer thickness at a predictable location, minimizing material loss and creating uniformly thick separated wafers that are easier to handle and process subsequently
Solution Approach 2:
The patent applies local quality by concentrating the stress induction and break initiation in a specific peripheral region of the wafer. This localized approach ensures consistent break propagation through the wafer, reducing material loss and creating uniformly thick separated wafers with improved handling characteristics
3Loss of substance
If conventional sawing is used for wafer production, then the separation process is well-established and reliable, but material loss reaches almost 50%
Solution Approach 1:
The patent extracts the need for physical material removal by replacing conventional sawing with a stress-induced breaking method. Instead of cutting through the wafer and removing material (kerf loss), the method induces controlled breaks that separate the wafer without removing any material, thereby eliminating kerf loss while maintaining manufacturing simplicity through a straightforward stress application process
Solution Approach 2:
The patent replaces the mechanical sawing system with a stress induction system that uses thermal expansion or mechanical forcing to create controlled breaks. This substitution eliminates the need for physical cutting and material removal, thereby eliminating kerf loss while maintaining ease of manufacture through a simplified process that requires only stress application and controlled break propagation
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 enables the production of wafers with reduced thickness variations and improved handling characteristics by controlling the break initiation, resulting in higher quality wafers with minimized material waste and cost.
Implementation Method 1
the polymer layer has a thermal expansion coefficient that is higher by approximately two orders of magnitude in comparison to the workpiece
Implementation Method 2
by utilising a glass transition a relatively high elasticity modulus can be achieved in the polymer layer so that sufficiently large stresses can be induced
Data Source
AI summary
A method of splitting a semiconductor wafer includes: inducing a first stress distribution in the semiconductor wafer by exposing the semiconductor wafer to a first radiation process; inducing a second stress distribution in the semiconductor wafer by exposing the semiconductor wafer to a second radiation process, the second radiation process including applying laser energy to an edge of the semiconductor wafer; and splitting the semiconductor wafer after inducing the first stress distribution and the second stress distribution.