Trench Gate Electrode Fill Material Structure for Ion Implantation Depth Control
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Solution Overview
Problem
Accurate control of ion implantation depths in semiconductor substrates with trenches is challenging, leading to variations in impurity densities and device performance due to difficulties in etching precision.
Innovation Solution
A semiconductor device manufacturing method involving the formation of a trench, a gate insulating film, and sequential deposition of first and second fill materials with differing etching resistances, where the second fill material is etched to a shallower position than the first, allowing for precise ion implantation depth control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fill material is deposited in the trench, then the manufacturing process is simple, but the etching accuracy and ion implantation depth control deteriorate
Solution Approach 1:
The fill material is divided into two distinct layers: a first fill material (polysilicon) and a second fill material (spin-on-glass). This segmentation allows differential etching where the second material etches slower, creating a protruding front surface that improves ion implantation depth control. The segmentation resolves the contradiction by adding structural complexity to achieve better manufacturing precision.
Solution Approach 2:
Different regions of the fill material are given different etching resistances through material selection. The second fill material (spin-on-glass) has higher etching resistance than the first fill material (polysilicon), creating local quality differences. This allows the center region to etch slower and protrude, providing a reference surface for accurate ion implantation depth control while maintaining overall process functionality.
2Productivity
If the etching speed is fast for uniform processing, then the productivity is high, but the etching accuracy and shape stability deteriorate
Solution Approach 1:
The patent applies local quality by making the second fill material (spin-on-glass) have higher etching resistance than the first fill material (polysilicon). This creates a controlled differential etching rate where the center region etches slower and protrudes, forming a stable reference surface. This resolves the contradiction by sacrificing overall etching speed to achieve superior etching accuracy and shape stability.
Solution Approach 2:
The dual-layer fill material structure is prepared in advance before ion implantation. The second fill material is deposited and configured to create a protruding front surface that will serve as a depth reference during subsequent ion implantation. This preliminary action ensures that when ion implantation occurs, the depth control is already optimized by the pre-formed surface topology.
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 method improves etching accuracy, stabilizes post-etch shapes, and reduces variations in impurity densities and device performance among semiconductor devices.
Implementation Method 1
depositing a first fill material on a side surface of the gate insulating film in the trench
Implementation Method 2
depositing a first fill material on a side surface of the gate insulating film in the trench; depositing a second fill material having a higher etching resistance than the first fill material on a side surface of the first fill material in the trench
Implementation Method 3
removing a part of the first fill material in the trench and a part of the second fill material in the trench by etching from a front surface side of the semiconductor substrate
Implementation Method 4
forming a diffusion layer after the etching by an ion implantation to the semiconductor substrate from the front surface side of the semiconductor substrate
Data Source
AI summary
Technique disclosed herein can suppress performance variation among semiconductor devices to be manufactured upon manufacturing each semiconductor device by forming diffusion layer by ion implantation to semiconductor substrate after etching. A semiconductor device includes a semiconductor substrate. The semiconductor substrate includes an emitter region, a top body region, a barrier region, a bottom body region, a drift region, a collector region, a trench, a gate insulating film, and a gate electrode. A front surface of the gate electrode is provided at a deeper position than a front surface of the semiconductor substrate. Within the gate electrode, a front surface of a first portion at a widthwise center of a trench is provided at a shallower position than a front surface of a second portion in contact with the gate insulating film.