Semiconductor Device Manufacturing Laser Power Density Control
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Solution Overview
Problem
Existing semiconductor manufacturing techniques using laser beams to form altered layers and peel off device layers result in variations in electrical characteristics due to unabsorbed laser beam intensity reaching the device structure, causing issues with leakage current and threshold voltage shifts.
Innovation Solution
Applying a laser beam to a predetermined depth in the semiconductor substrate with a lower power density in the region corresponding to the channel of the device structure, either by controlling laser application coordinates, using a laser shielding film, or creating a damage region to reduce laser beam transmission, thereby suppressing variations in electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a laser beam is applied to form an altered layer at a predetermined depth in the semiconductor substrate, then the device layer can be peeled off from the substrate, but the unabsorbed laser beam intensity reaches the device structure causing variations in electrical characteristics
Solution Approach 1:
The patent applies local quality by creating a damage region at the lower surface of the semiconductor substrate in the region corresponding to the channel of the device structure. This damage region serves as a localized barrier that selectively blocks laser beam transmission only where needed (under the channel), while allowing laser processing to proceed normally in other regions. The damage region can be formed by various methods including laser irradiation, particle beam irradiation, or chemical etching, and it provides different protection levels for different areas of the device structure.
Solution Approach 2:
The damage region acts as an intermediary element between the laser beam and the device structure. Instead of directly exposing the device structure to the laser beam, the damage region is introduced as an intermediate layer that absorbs or blocks the laser energy. This intermediary structure prevents the harmful laser effects from reaching the sensitive device components while still allowing the laser to effectively create the altered layer for device layer peeling in regions where no damage region is present.
2Reliability
If the laser beam power density is reduced in the region corresponding to the channel, then variations in electrical characteristics are suppressed, but the effectiveness of device layer peeling may be compromised
Solution Approach 1:
The patent implements local quality by spatially differentiating the laser processing approach: in regions corresponding to device structures (particularly channels), a damage region is created to block laser transmission and protect electrical characteristics; in other regions without device structures, normal laser irradiation proceeds to create effective altered layers for peeling. This localized approach ensures that each region receives the appropriate treatment for its specific function.
Solution Approach 2:
The patent segments the semiconductor substrate into different functional zones: regions with device structures that require protection from laser exposure, and regions without device structures that require effective laser processing for peeling. The damage regions are selectively positioned in specific segments (under channels) while leaving other segments open to laser processing, thereby achieving both protection and effective peeling through spatial segmentation of the processing approach.
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 method effectively reduces variations in electrical characteristics by lowering the unabsorbed laser beam intensity at the device structure, allowing for consistent semiconductor device performance and enabling the reuse of semiconductor substrates.
Implementation Method 1
applying of a laser beam to a plane extending at a predetermined depth in a semiconductor substrate
Implementation Method 2
forming an altered layer inside of a semiconductor substrate by irradiating a plane extending at a predetermined depth inside of the semiconductor substrate with a laser beam
Data Source
AI summary
A method for manufacturing a semiconductor device, includes: applying a laser beam to a plane extending at a predetermined depth in a semiconductor substrate from a second main surface side of the semiconductor substrate opposite to a first main surface side on which a device structure including a channel is formed; and peeling off a device layer including the device structure from the semiconductor substrate along the plane applied with the laser beam. In the applying of the laser beam, the laser beam is applied so that a power density is lower in a region corresponding to the channel in a thickness direction of the semiconductor substrate than in the other region, in the plane extending at the predetermined depth in the semiconductor substrate.