Single-Crystal Silicon Wafer Separation With Minimal Back Grinding
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Solution Overview
Problem
The existing methods for processing single-crystal silicon wafers require significant grinding of the back surface, leading to excessive wear on grinding tools, contamination of the grinding apparatus, and increased maintenance burdens.
Innovation Solution
A processing method that forms dividing origins at a depth corresponding to the finished thickness of device chips and creates a separation layer along the crystal plane of the second surface using a pulsed laser beam, allowing for the separation of the wafer into device and non-device sides without extensive grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the back surface side is ground to divide the wafer into multiple device chips, then the wafer can be divided into chips, but the amount of wear of grinding abrasive stones is comparatively large
Solution Approach 1:
The invention divides the wafer processing into two distinct stages: first forming dividing origins along planned dividing lines, then creating a separation layer at a different depth. This segmentation allows the wafer to be separated with minimal grinding, reducing abrasive stone wear while maintaining division capability.
Solution Approach 2:
The invention performs preliminary actions by forming dividing origins and a separation layer before the final division step. The dividing origins are created at the finished thickness depth, and the separation layer is formed at a deeper position, enabling subsequent easy separation with minimal material removal.
2Productivity
If the back surface side is ground to divide the wafer into multiple device chips, then the wafer can be divided into chips, but a lot of grinding dust is generated which contaminates the grinding apparatus
Solution Approach 1:
By segmenting the processing into origin formation and separation layer creation at different depths, the invention enables precise separation with minimal grinding. This reduces grinding dust generation and prevents contamination of the grinding apparatus while maintaining effective wafer division.
3Productivity
If the back surface side is ground to divide the wafer into multiple device chips, then the wafer can be divided into chips, but frequent cleaning of the grinding apparatus is required which is troublesome
Solution Approach 1:
The invention performs preliminary formation of dividing origins and separation layer before final division. This preliminary action enables the wafer to be separated with minimal grinding, significantly reducing the frequency of apparatus cleaning and making maintenance less troublesome.
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 reduces the amount of grinding required, minimizes tool wear and contamination, and simplifies maintenance, while effectively separating the wafer into device and non-device sides.
Implementation Method 1
positioning a focal point of a pulsed laser beam having such a wavelength as to be transmitted through the single-crystal silicon wafer to the inside of the single-crystal silicon wafer and relatively moving the focal point and the single-crystal silicon wafer along a first direction
Implementation Method 2
forming modified regions by relatively moving the focal point of the laser beam and the single-crystal silicon wafer along the first direction and an indexing feed step of executing indexing feed of the focal point and the single-crystal silicon wafer relatively in a second direction
Data Source
AI summary
A processing method for processing a single-crystal silicon wafer that has a first surface and a second surface formed in such a manner that a specific crystal plane included in a crystal plane {100} is exposed in each of the first and second surfaces and has devices formed in the respective regions marked out by planned dividing lines in the first surface. The method includes forming dividing origins along each planned dividing line, forming a separation layer along the crystal plane of the second surface through relatively moving a focal point and the wafer along a first direction that is parallel to the crystal plane of the second surface and in which an acute angle formed between the first direction and the crystal orientation <100> is equal to or smaller than 5°, and separating the wafer into a first-surface-side wafer including devices and a second-surface-side wafer including no devices.