Silicon Carbide Wafer Composite Laser Separation

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Solution Overview

Problem

There is a need for improved methods to manufacture silicon carbide devices economically, particularly in providing substrates that minimize the propagation of microcracks during the laser radiation process, which affects the reliability and efficiency of the wafer separation.

Innovation Solution

A method involving a wafer composite with a handle substrate, an auxiliary layer, and a silicon carbide structure, where the auxiliary layer is formed on the handle substrate to stop the propagation of microcracks generated by laser radiation, allowing for a more efficient and reliable separation process by restricting the vertical extension of cracks and reducing material loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If laser radiation is applied to the handle substrate to modify crystalline material, then the separation process is enabled, but microcracks propagate through the silicon carbide structure causing damage

Engineering Contradiction:

Improveseparation processVSAvoidcrystal defects

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

An auxiliary layer is introduced as an intermediary component between the handle substrate and the silicon carbide structure. This auxiliary layer acts as a mediator that stops microcrack propagation, preventing cracks from reaching the silicon carbide structure while still allowing the laser radiation process to proceed for separation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The auxiliary layer is positioned in advance to cushion against the harmful effects of laser-induced microcracks. By placing this protective layer beforehand, the system prepares for potential crack propagation and neutralizes the damage before it can affect the silicon carbide structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If laser radiation is used to modify crystalline material in the handle substrate, then wafer separation is achieved, but material loss occurs due to crack propagation

Engineering Contradiction:

Improvewafer separationVSAvoidcrystalline silicon carbide

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The auxiliary layer serves as a protective intermediary that intercepts microcracks generated during laser radiation. By stopping crack propagation at the auxiliary layer, the silicon carbide structure remains intact, minimizing material loss while maintaining productive wafer separation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The auxiliary layer converts the potentially harmful laser-induced microcracks into a beneficial separation mechanism. The cracks are directed to propagate only within the auxiliary layer and handle substrate, which are then removed, leaving the silicon carbide structure intact and minimizing material loss.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the auxiliary layer is introduced to stop microcrack propagation, then crystal defects are prevented, but the device structure becomes more complex

Engineering Contradiction:

Improvecrystal defectsVSAvoidwafer composite structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The auxiliary layer is designed to be a temporary component that is removed after serving its protective function. By extracting this layer after wafer separation, the final device structure does not retain the added complexity, as the auxiliary layer is discarded after preventing crystal defects during manufacturing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The auxiliary layer is discarded after fulfilling its protective role in stopping microcrack propagation. This temporary component is removed in subsequent processing steps, so while it adds complexity during manufacturing, it does not remain in the final device structure.

Inventive Principle:

Principle #34Discarding and recovering

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

The auxiliary layer effectively shields the silicon carbide structure from laser-induced crystal defects, enabling a reliable and reproducible separation process with minimal loss of crystalline silicon carbide, thus improving the efficiency of silicon carbide device manufacturing.

Implementation Method 1

The handle substrate is subjected to laser radiation. The laser radiation modifies crystalline material along a focal plane in the handle substrate

Methodology Applied

Scientific EffectLaser radiation: Laser

Implementation Method 2

The laser radiation modifies crystalline material along a focal plane in the handle substrate

Methodology Applied

Scientific EffectThermal stress: Thermal Expansion

Implementation Method 3

The auxiliary layer is configured to stop propagation of microcracks that the laser radiation generates in the handle substrate

Methodology Applied

Scientific EffectCrack propagation: Fracture Mechanics

Data Source

PatentUS11373863B2Method of manufacturing a silicon carbide device and wafer composite including laser modified zones in a handle substrate

Publication Date: 2022.06.28 INFINEON TECHNOLOGIES AG

AI summary

A wafer composite includes a handle substrate, an auxiliary layer formed on a first main surface of the handle substrate, and a silicon carbide structure formed over the auxiliary layer. The handle substrate is subjected to laser radiation that modifies crystalline material along a focal plane in the handle substrate. The focal plane is parallel to the first main surface. The auxiliary layer is configured to stop propagation of microcracks that the laser radiation may generate in the handle substrate.