Semiconductor Wafer Slicing via Cylindrical Block Grinding
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Solution Overview
Problem
Existing methods for producing semiconductor wafers with specific crystal lattice orientation result in yield losses due to wedge-shaped products and complex block orientation in wire saws, leading to inefficient cutting and oval wafer shapes.
Innovation Solution
A method involving slicing a single crystal block along cutting planes perpendicular to the crystallographic axis representing the sought orientation, followed by grinding the lateral surface to form a cylindrical block, allowing for efficient slicing of semiconductor wafers without wedge-shaped waste and enabling simultaneous cutting of multiple blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If blocks are sliced from the single crystal along cutting planes perpendicular to the central longitudinal axis and then ground around the central longitudinal axis, then cylindrical blocks are obtained, but wedge-shaped products arise at the end sides of the block which lower the yield
Solution Approach 1:
The patent applies preliminary action by performing a first slicing step to create a block with a ground lateral surface around the central longitudinal axis before the main slicing operation. This preliminary preparation ensures that subsequent slicing planes perpendicular to the crystallographic axis produce round wafers without wedge-shaped waste, eliminating yield loss while maintaining the desired cylindrical shape.
2Manufacturing precision
If the block is oriented in the wire saw to slice wafers perpendicular to the crystallographic axis, then correctly oriented wafers are produced, but the orientation process is complicated and susceptible to faults
Solution Approach 1:
The patent applies self-service by creating ground reference surfaces on the block that automatically indicate the correct orientation for slicing. The ground lateral surface and end surfaces serve as self-aligning references that guide the slicing operation without requiring complex external orientation equipment or procedures, thereby maintaining precise crystal lattice orientation while simplifying the overall process.
3Shape
If cutting planes are positioned to slice perpendicular to the crystallographic axis, then round wafers are produced, but simultaneous cutting of multiple blocks is not possible
Solution Approach 1:
The patent applies segmentation by dividing the single crystal into multiple separately prepared blocks, each with ground reference surfaces. This allows each block to be independently oriented and sliced simultaneously using multiple wire saws or cutting zones, thereby maintaining round wafer shape while enabling parallel processing to improve overall productivity and throughput.
4Productivity
If the wire web is utilized completely by arranging multiple blocks, then throughput is optimized, but wedge-shaped waste products still arise
Solution Approach 1:
The patent applies preliminary action by preparing each block with ground lateral and end surfaces around the central longitudinal axis before arrangement for simultaneous slicing. This preliminary preparation ensures that when multiple blocks are arranged to fully utilize the wire web for optimized throughput, each block produces only round wafers without wedge-shaped waste, thereby eliminating yield loss while maintaining high productivity.
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 ensures semiconductor wafers with the desired crystal lattice orientation are produced without yield losses, allowing for complete utilization of the wire saw web and facilitating the production of round wafers with improved throughput, especially for large diameter wafers like 300 mm or 450 mm silicon wafers.
Implementation Method 1
Wire saws are usually used for slicing the semiconductor wafers. In the course of the sawing operation, the wires penetrate through the block, as a result of which a number of semiconductor wafers corresponding to the number of gaps between the wires penetrating through the block arise simultaneously.
Implementation Method 2
A lateral surface of the block is ground around the central longitudinal axis
Implementation Method 3
the reworking generally comprises slicing the block from the single crystal along cutting planes perpendicular to the central longitudinal axis of the single crystal
Data Source
AI summary
A method for producing a plurality of semiconductor wafers includes processing a single crystal. The single crystal is provided in a grown state and has a central longitudinal axis with an orientation that deviates from a sought orientation of a crystal lattice of the semiconductor wafers. A block is sliced from the single crystal along cutting planes perpendicular to a crystallographic axis corresponding to the sought orientation of the crystal lattice of the semiconductor wafers. A lateral surface of the block is ground around the crystallographic axis. A plurality of semiconductor wafers are then sliced from the ground block along cutting planes perpendicular to the crystallographic axis.