Semiconductor Emitter Width Control via Silicon Film Masking
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Solution Overview
Problem
Conventional methods for manufacturing high-frequency heterojunction bipolar transistors with SiGe base layers require high precision exposure apparatuses, increasing manufacturing costs and complexity.
Innovation Solution
A method involving the formation of a conductive layer and a silicon film on a semiconductor substrate, followed by etching and impurity diffusion to create a reversed T-shaped emitter layer, reducing the emitter-base junction width without the need for high precision exposure tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high precision exposure apparatus is used to reduce emitter layer width, then device performance is improved, but manufacturing cost increases
Solution Approach 1:
A silicon film is introduced as an intermediary layer between the emitter layer and the underlying structures. This silicon film enables precise width control through selective etching processes, achieving the required manufacturing precision without necessitating expensive high-precision exposure apparatus. The silicon film acts as a mediator that facilitates dimension control through alternative manufacturing approaches.
2Manufacturing precision
If emitter layer width is reduced to improve performance, then device performance and power efficiency are improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct stages: forming the silicon film, depositing the emitter layer, and performing selective etching. This segmentation allows each process step to be optimized independently, reducing overall manufacturing complexity while achieving precise emitter layer width control. The silicon film serves as a separate, controllable element that simplifies the overall fabrication sequence.
3Ease of manufacture
If conventional etching methods are used, then manufacturing process is simple, but emitter-base junction width cannot be sufficiently reduced
Solution Approach 1:
The invention introduces a vertical dimension control mechanism by forming a silicon film at a specific depth below the emitter layer. This vertical positioning, combined with selective lateral etching, enables precise control of the emitter-base junction width. The solution moves from purely lateral dimension control to a combination of vertical and lateral dimension control, achieving higher precision through multi-dimensional process integration.
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 the emitter layer width, achieving higher performance and lower power consumption in semiconductor devices while minimizing manufacturing costs.
Implementation Method 1
a sixth step of diffusing the first impurity contained in the emitter electrode into a surface of the silicon film to form in the silicon film a first region containing the first impurity and a second region free of the first impurity
Implementation Method 2
a fourth step of forming an insulative film entirely covering the semiconductor substrate and then etching back the insulative film to form a side wall film covering a side surface of the emitter electrode
Data Source
AI summary
A semiconductor device manufacturing method including forming a conductive layer and a silicon film on a semiconductor substrate including an active region, forming an emitter electrode containing a first impurity on the silicon film above the active region, partially etching the silicon film using the emitter electrode as a mask, forming an insulative film covering the semiconductor substrate and a side wall film covering a side surface of the emitter electrode, introducing a second impurity into the conductive layer and silicon film so that the second impurity reaches the active region to form an impurity region containing the second impurity in parts of the conductive layer and silicon film, and diffusing the first impurity contained in the emitter electrode into the silicon film to form in the silicon film a first region containing the first impurity and a second region free of the first impurity.