Bipolar Transistor Collector on Polycrystalline Isolation Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bipolar transistors, particularly those using non-conventional semiconductor materials, require costly etching and regrowing processes, leading to increased manufacturing costs and operational parameter challenges.
Innovation Solution
A bipolar transistor structure is developed with a polycrystalline isolation layer, a collector layer of a first doping type, a base layer of a second opposite doping type, and an emitter layer of the first doping type, where the material composition of the collector layer differs from the base layer, allowing for partial processing and reduced material removal, and utilizing epitaxial growth for semiconductor material deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional bipolar transistors use non-conventional semiconductor materials with etching and regrowing processes, then material composition flexibility is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent applies preliminary action by forming the collector layer on a polycrystalline isolation layer before base layer formation, establishing the heterojunction structure in advance. This preliminary configuration enables material composition flexibility while avoiding costly etching and regrowing processes that would be needed if material changes were made later in the fabrication sequence.
Solution Approach 2:
The polycrystalline isolation layer serves as an intermediary between the substrate and the collector layer, enabling the use of non-conventional semiconductor materials in the collector without requiring etching of underlying layers. This intermediary structure facilitates material composition flexibility while simplifying the manufacturing process.
2Manufacturing precision
If multiple etching and regrowing operations are performed to achieve desired material locations, then material placement precision is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The collector layer is preliminarily formed on the polycrystalline isolation layer with the correct material composition and doping type before base layer formation. This preliminary positioning achieves material placement precision without requiring multiple etching and regrowing cycles, thereby reducing device complexity and processing steps.
3Reliability
If heterojunction structure with different material compositions is implemented, then operational parameters are improved, but manufacturing process complexity increases
Solution Approach 1:
The patent implements local quality by creating a heterojunction structure where the collector layer has a different material composition than the base layer, with each layer optimized for its specific function. The collector layer uses non-conventional semiconductor materials with specific doping types to achieve superior operational parameters, while the polycrystalline isolation layer provides electrical isolation. This localized material differentiation improves operational parameters without requiring complex global process changes.
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 manufacturing costs and improves operational parameters by enabling efficient formation of bipolar transistors with a heterojunction structure, minimizing material processing and integration with CMOS structures, while maintaining electrical isolation and conductivity.
Implementation Method 1
a polycrystalline isolation layer on a substrate; a collector layer over the polycrystalline isolation layer
Implementation Method 2
the collector layer having a first doping type; the base layer having a second doping type opposite the first doping type; the emitter layer having the first doping type
Data Source
AI summary
Embodiments of the disclosure provide a bipolar transistor structure with a collector on a polycrystalline isolation layer. A polycrystalline isolation layer may be on a substrate, and a collector layer may be on the polycrystalline isolation layer. The collector layer has a first doping type and includes a polycrystalline semiconductor. A base layer is on the collector layer and has a second doping type opposite the first doping type. An emitter layer is on the base layer and has the first doping type. A material composition of the doped collector region is different from a material composition of the base layer.