GaN Wafer Reflective Layer for Heat-Safe Laser Slicing
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices using laser slicing of gallium nitride wafers is the degradation of device characteristics due to heat generated when laser beams leak and are absorbed by device constituent parts, leading to potential heat-induced adverse effects on the GaN crystal.
Innovation Solution
A reflective layer with a refractive index different from the epitaxial layer is positioned to reflect laser beams away from the device constituent parts, preventing heat generation and absorption, thereby maintaining device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser slicing is performed on processed wafer, then wafer can be divided into multiple wafers, but laser beam leaks and generates heat that degrades device characteristics
Solution Approach 1:
A reflective layer is introduced as an intermediary component between the laser beam path and the device constituent parts. This reflective layer intercepts and redirects the leaked laser beam, preventing direct heating of the devices while allowing the laser slicing process to continue effectively
Solution Approach 2:
The reflective layer is positioned in advance at a location where leaked laser beams are expected to travel. By placing this protective structure beforehand, the harmful thermal effects on device characteristics are prevented before they can occur during the laser slicing operation
2Ease of manufacture
If laser beam is applied from back surface side to form modified layer, then processing can be performed, but leaked laser beam is absorbed by device constituent parts causing heat generation
Solution Approach 1:
The reflective layer serves as a mediating structure that intercepts the leaked laser beam before it reaches the device constituent parts. By reflecting the beam away from sensitive areas, it prevents unwanted heat generation while maintaining the effectiveness of the laser slicing process
Solution Approach 2:
The reflective layer converts the potentially harmful leaked laser beam into a beneficial reflected path that does not interfere with device integrity. The leaked beam, which would otherwise cause damage, is redirected to safely exit the system without affecting the processed wafer or devices
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 reflective layer effectively suppresses the arrival of laser beams to the front surface-side device constituent parts, preventing heat generation and maintaining device integrity during the laser slicing process.
Implementation Method 1
The processed wafer prepared includes a reflective layer for reflecting the laser beam
Implementation Method 2
forming a modified layer in the processed wafer by applying a laser beam from a back surface side
Implementation Method 3
heat generated when laser beams leak and are absorbed by device constituent parts
Data Source
AI summary
A method for manufacturing a semiconductor device includes: preparing a processed wafer having a gallium nitride (GaN) wafer and an epitaxial layer on the GaN wafer; forming a device constituent part in a portion of the processes wafer adjacent to a front surface provided by the epitaxial layer; forming a modified layer inside of the processed wafer by applying a laser beam from a back surface side opposite to the front surface side; and dividing the processed wafer at the modified layer. The processed wafer prepared includes a reflective layer for reflecting the laser beam at a position separated from a planned formation position, where the modified layer is to be formed, by a predetermined distance toward the front surface side. The reflective layer contains a layer having a refractive index different from that of a GaN single crystal of an epitaxial layer.