Semiconductor Device Thickness Control via Auxiliary Structure
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Solution Overview
Problem
Semiconductor devices, such as MOSFETs and IGBTs, face challenges in maintaining consistent device parameters due to thickness variations in the semiconductor body, which affect blocking voltage capability and on-state resistance.
Innovation Solution
A method involving the formation of an auxiliary structure at one surface of a silicon semiconductor body, followed by the growth of a semiconductor layer and the removal of the substrate from the opposite surface up to the edge of the auxiliary structure, using techniques like ion implantation and etching to minimize thickness variations and achieve precise surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional semiconductor manufacturing processes are used, then device fabrication is straightforward, but thickness variations of the semiconductor body cause spread in device parameters such as blocking voltage capability and on-state resistance
Solution Approach 1:
An auxiliary structure is formed on the semiconductor body before final processing steps. This auxiliary structure serves as a reference landmark that enables precise thickness control during subsequent substrate removal. By establishing this reference structure in advance, the method achieves reduced thickness variation (e.g., total thickness variation of 1 μm or less) and improved consistency of device parameters without requiring complex real-time measurement and adjustment systems.
2Manufacturing precision
If the semiconductor substrate is removed to reduce thickness variation, then device parameter consistency improves, but the process becomes more complex and time-consuming
Solution Approach 1:
The auxiliary structure acts as an intermediary element between the manufacturing process and the final device. It provides a stable reference that simplifies the substrate removal process by enabling precise depth control without requiring complex measurement systems. The auxiliary structure mediates between the need for high precision and the desire for process simplicity, allowing standard etching or mechanical removal techniques to achieve high precision results.
3Manufacturing precision
If extensive substrate removal is performed to achieve uniform thickness, then thickness variation reduces, but manufacturing time and material loss increase
Solution Approach 1:
The auxiliary structure is formed beforehand to establish precise depth references for substrate removal. This preliminary action enables selective and controlled removal of substrate material, allowing the process to stop exactly when the desired thickness is achieved. Consequently, material removal is optimized - sufficient to achieve uniform thickness (e.g., 50-150 μm) but not excessive, thereby reducing both manufacturing time and material waste while maintaining high precision.
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 allows for a semiconductor device with reduced total thickness variation and well-defined surface roughness in the micro- or nanometer range, enhancing the consistency of device parameters like blocking voltage and on-state resistance.
Implementation Method 1
using techniques like ion implantation and etching to minimize thickness variations
Implementation Method 2
forming a silicon layer on the semiconductor body at the first surface
Implementation Method 3
removing the semiconductor substrate from a second surface opposite to the first surface at least up to an edge of the auxiliary structure
Data Source
AI summary
In accordance with a method of forming a semiconductor device, an auxiliary structure is formed at a first surface of a silicon semiconductor body. A semiconductor layer is formed on the semiconductor body at the first surface. Semiconductor device elements are formed at the first surface. The semiconductor body is then removed from a second surface opposite to the first surface at least up to an edge of the auxiliary structure oriented to the second surface.