Semiconductor Absorption Layer Splitting for Thin Low-Resistance Substrates
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Solution Overview
Problem
Existing methods for forming semiconductor devices, such as MOSFETs and IGBTs, face challenges in improving area-specific on-state resistance and substrate costs, particularly in reducing the thickness of semiconductor devices for better device characteristics and efficient substrate utilization.
Innovation Solution
A method involving ion implantation to form an absorption layer in a parent substrate, followed by splitting along a detachment layer using a focused laser beam or ion implantation to create a high absorption coefficient layer, allowing for controlled substrate separation while minimizing damage to the semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of semiconductor devices is reduced to improve device characteristics, then area-specific on-state resistance is improved, but manufacturing precision and control of doping concentration become more difficult
Solution Approach 1:
The substrate is divided into a parent substrate and a device substrate through the detachment layer. The absorption layer is formed in the parent substrate at a specific depth, enabling selective separation that preserves the doped region in the device substrate while removing the rest of the parent substrate, thus maintaining precise doping control in thin devices
Solution Approach 2:
The absorption layer is formed in advance in the parent substrate at a predetermined depth using ion implantation, before the detachment layer is formed and before the final device structure is completed. This preliminary doping action ensures precise concentration control is achieved before subsequent processing steps
2Manufacturing precision
If ion implantation is used to form an absorption layer, then controlled substrate separation is achieved, but energy absorption in the wiring area increases which may damage gate oxide
Solution Approach 1:
The absorption layer is formed with specific local properties (high absorption coefficient) at a predetermined depth in the parent substrate, while other regions maintain their original properties. This localized quality ensures energy is absorbed primarily at the absorption layer location during laser irradiation, protecting the gate oxide in the wiring area from excessive energy exposure
Solution Approach 2:
The absorption layer acts as an intermediary that selectively absorbs laser energy during the substrate separation process. By positioning this layer at a specific depth and giving it high absorption properties, it mediates the energy distribution, preventing energy from reaching and damaging the gate oxide in the wiring area while still enabling effective substrate separation
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 approach reduces energy absorption in the wiring area, enhances gate oxide reliability, and improves current flow characteristics by limiting temperature exposure during splitting, resulting in more efficient semiconductor devices with reduced on-state resistance and lower substrate costs.
Implementation Method 1
forming an absorption layer in the parent substrate by an ion implantation process of an element through a first surface of the parent substrate
Implementation Method 2
creating a high absorption coefficient layer, allowing for controlled substrate separation
Implementation Method 3
splitting along a detachment layer using a focused laser beam
Implementation Method 4
reduces energy absorption in the wiring area, enhances gate oxide reliability, and improves current flow characteristics by limiting temperature exposure during splitting
Data Source
AI summary
A method of manufacturing a semiconductor device is described. The method includes providing a parent substrate including a substrate portion of a first conductivity type. The method further includes forming an absorption layer in the parent substrate by an ion implantation process of an element through a first surface of the parent substrate. The method further includes forming a semiconductor layer structure on the first surface of the parent substrate. The method further includes splitting the parent substrate along a splitting section through a detachment layer. The detachment layer is arranged between the absorption layer and a second surface of the parent substrate at a vertical distance to the absorption layer.