Bipolar Transistor Collector Layout Across an Insulating Trench
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Solution Overview
Problem
Current bipolar transistor manufacturing methods face challenges in achieving efficient and defect-free formation of collector regions, particularly in ensuring proper contact and alignment between homogeneously and gradually doped layers, which affects the transistor's performance and capacity.
Innovation Solution
The method involves forming a first substantially homogeneously doped layer at the bottom of a cavity, followed by a second gradually doped layer through diffusion, with an insulating trench filled with material, and forming a portion of the collector that crosses this trench, ensuring physical contact and minimizing defects by using epitaxial growth and low-power dopant implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a bipolar transistor is manufactured using conventional methods with separate formation of homogeneously and gradually doped layers, then the manufacturing process is simpler, but alignment defects and contact issues occur between layers
Solution Approach 1:
The collector is divided into two distinct portions: a first portion extending under the insulating trench with homogeneous doping, and a second portion crossing the trench with gradual doping. This segmentation allows each portion to be optimized independently for its specific function while ensuring proper alignment through the trench-crossing geometry of the second portion.
Solution Approach 2:
The insulating trench acts as an intermediary element that physically separates and electrically isolates different regions of the collector. By filling the trench with insulating material and having the first collector portion extend underneath it, the structure ensures precise alignment and contact between the homogeneously and gradually doped regions without direct contamination or misalignment issues.
2Reliability
If intrinsic semiconductor material is used to separate collector portions, then electrical isolation is achieved, but collector capacity increases and performance decreases
Solution Approach 1:
The invention extracts and removes the intrinsic semiconductor separation layer from the collector structure. Instead of using intrinsic material to isolate collector portions, the structure relies on the insulating trench filling and the geometric arrangement of the two collector portions, thereby reducing collector capacity while maintaining electrical isolation.
Solution Approach 2:
Electrical isolation is achieved locally at the trench region where insulating material is deposited, rather than using a widespread intrinsic layer throughout the collector structure. This localized isolation approach minimizes the impact on overall collector capacity and transistor performance while providing sufficient electrical separation where needed.
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 enhances the contact between collector portions, reduces defects, and improves the transistor's capacity by maintaining a smaller collector capacity without the need for intrinsic semiconductor separation, thus overcoming alignment and defect issues in existing methods.
Implementation Method 1
forming a second gradually doped layer by diffusion of the dopants of the first layer
Implementation Method 2
the method comprises implanting dopants into regions in contact with the second layer
Data Source
AI summary
A bipolar transistor includes a collector. The collector is formed by: a first portion of the collector which extends under an insulating trench, and a second portion of the collector which crosses through the insulating trench. The first and second portions of the collector are in physical contact.