Trench-Embedded PN Junction Diodes for Flat Semiconductor Surfaces
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Solution Overview
Problem
The manufacturing process of semiconductor devices using 200 mm and 300 mm wafers faces challenges in achieving flatness due to steps on the semiconductor substrate, particularly when forming contact plugs, which complicates the process and increases difficulty, especially for power transistors and optional elements like temperature detection diodes and gate protection diodes.
Innovation Solution
The solution involves forming trenches in the semiconductor substrate with insulating films and embedding p-type and n-type semiconductor portions within these trenches, allowing the formation of pn junction diodes that function as gate protection and temperature detection diodes, eliminating the need for polysilicon films that cause substrate steps and enhancing the flatness of the semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polysilicon films are formed on the semiconductor substrate to create optional elements, then the optional elements (temperature detection diodes and gate protection diodes) can be formed, but steps are generated on the surface of the semiconductor substrate, making subsequent contact plug formation difficult
Solution Approach 1:
The patent merges the formation of optional elements (temperature detection diodes and gate protection diodes) with the existing trench structure by embedding semiconductor portions directly into the trench. This eliminates the need for separate polysilicon film formation on the surface, thereby maintaining surface flatness while still creating the required optional elements within the trench volume.
Solution Approach 2:
The patent transitions from surface-level element formation (polysilicon films on the substrate surface) to volume-based element formation (embedding semiconductor portions within the trench). This dimensional shift from 2D surface formation to 3D internal structure formation allows optional elements to be created without compromising surface flatness.
2Productivity
If 300 mm semiconductor wafers are used instead of 200 mm wafers, then manufacturing line advancement is achieved, but the complexity and difficulty of the manufacturing process increases due to surface steps
Solution Approach 1:
The patent extracts the source of manufacturing complexity (surface steps caused by polysilicon film formation) by eliminating the polysilicon film formation step entirely. Instead, optional elements are formed by embedding semiconductor portions within the existing trench structure, thereby simplifying the manufacturing process while maintaining compatibility with advanced 300 mm wafer production lines.
3Adaptability or versatility
If polysilicon films are used to form optional elements, then the elements can be created, but the manufacturing process becomes more complicated and costly
Solution Approach 1:
The patent combines the formation of multiple optional elements (temperature detection diodes and gate protection diodes) into a single integrated process step by embedding semiconductor portions directly into the trench. This eliminates the need for separate polysilicon film deposition, patterning, and etching steps, thereby simplifying the manufacturing process while still creating all required optional elements.
Data Source
AI summary
A semiconductor device includes a trench formed in an element formation region of a semiconductor substrate, an insulating film formed on an inner wall of the trench, a p-type semiconductor portion embedded in a part of the trench via the insulating film, and an n-type semiconductor portion embedded in another part of the trench via the insulating film and provided so as to contact with the p-type semiconductor portion.