Semiconductor Wafer Detachment Plane Splitting for Thin Slice Testing
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Solution Overview
Problem
Thinning semiconductor wafers for vertical power devices is resource-intensive and complicates handling due to brittleness, making it difficult to electrically contact both sides for measuring electrical characteristics, and smaller lateral dimensions require smaller pads with larger connectors for high current flow.
Innovation Solution
Generating defects inside the semiconductor wafer to create a detachment plane, attaching a glass structure with openings to the processed surface, applying a polymer layer, and cooling to split the wafer into a semiconductor slice with the glass structure, which allows for electrical connection via a clip with a sufficient cross-section for high current conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the semiconductor wafer is thinned by etching, grinding, or sawing, then the final thickness is reduced, but the process becomes time-consuming and resource-intensive
Solution Approach 1:
A detachment plane is created inside the wafer before thinning by generating defects at a specific depth using laser irradiation. This preliminary action defines the separation plane in advance, enabling subsequent easy separation and reducing the actual thinning time required
Solution Approach 2:
The patent utilizes the phase transition of a polymer layer from rubbery to glassy state by cooling it below its glass transition temperature. This phase change causes the polymer to contract and pull the wafer along, enabling clean separation along the pre-defined detachment plane without requiring extensive mechanical processing
2Length of moving object
If the semiconductor wafer is thinned, then the thickness is reduced, but handling becomes complicated due to brittleness
Solution Approach 1:
A polymer layer is applied as an intermediary between the wafer and the separation process. This polymer layer adheres to the wafer back surface and, when cooled below its glass transition temperature, contracts to pull the wafer cleanly along the detachment plane. This intermediary enables easy handling and separation of thin wafers without direct mechanical contact that could cause breakage
3Ease of operation
If the wafer is mounted on a carrier for secure handling, then handling is improved, but electrical contact on both sides becomes impossible
Solution Approach 1:
The detachment plane is created inside the wafer before mounting on any carrier. This allows the wafer to be separated into thin slices while still on the manufacturing line, enabling electrical measurements to be performed on both sides of the wafer before it is mounted on a carrier for final handling and packaging
4Area of moving object
If lateral dimensions are decreased, then device size is reduced, but pad size becomes smaller making electrical connection difficult
Solution Approach 1:
A glass structure with openings is introduced as an intermediary element. The glass structure has openings that expose the small pads on the semiconductor surface, while the glass material itself provides a robust platform for attaching electrical connectors. This intermediary allows connectors with sufficient cross-section for high current flow to be attached without requiring the connectors to directly contact the small pads, thus resolving the contradiction between small device dimensions and easy electrical connection
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
Enables efficient thinning and electrical connection of semiconductor wafers, allowing for the measurement of electrical characteristics and high current conduction without the need for additional carriers, while minimizing sawing losses and stabilizing the thin slices with a glass structure.
Implementation Method 1
splitting the semiconductor wafer into a semiconductor slice and a remaining semiconductor wafer by cooling the polymer layer beneath its glass transition temperature
Data Source
AI summary
A method for processing a semiconductor wafer is provided. A semiconductor wafer includes a first main surface and a second main surface. Defects are generated inside the semiconductor wafer to define a detachment plane parallel to the first main surface. Processing the first main surface defines a plurality of electronic semiconductor components. A glass structure is provided which includes a plurality of openings. The glass structure is attached to the processed first main surface, each of the plurality of openings leaving a respective area of the plurality of electronic semiconductor components uncovered. A polymer layer is applied to the second main surface and the semiconductor wafer is split into a semiconductor slice and a remaining semiconductor wafer by cooling the polymer layer beneath its glass transition temperature along the detachment plane. The semiconductor slice includes the plurality of electronic semiconductor components.