Self-Aligned Bipolar Transistor with Shared Base-Collector Potential
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bipolar transistors used in overheat protection circuits are not designed to reduce area, leading to increased size and manufacturing costs, and variations in device characteristics due to non-self-aligned emitter regions.
Innovation Solution
A bipolar transistor design where the high concentration impurity regions for the collector and base electrodes are brought into direct contact to share the same potential, eliminating the need for device isolation and allowing for self-aligned formation of the emitter region using polycrystalline silicon, thereby reducing device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field oxide film is arranged between the emitter region and base high concentration impurity region, and between the base high concentration impurity region and collector high concentration impurity region, then device isolation is achieved, but the device area increases
Solution Approach 1:
The invention extracts and eliminates the field oxide film (device isolation structure) from the bipolar transistor configuration. By bringing the base and collector regions into direct contact, the patent removes the isolating field oxide film that traditionally prevented electrical interaction between these regions, thereby reducing device area while maintaining functional isolation through the bipolar transistor's inherent structure
Solution Approach 2:
The invention merges the base and collector regions by bringing them into direct contact through the same metal electrode. This merging eliminates the need for physical separation structures like field oxide films, allowing the regions to share the same potential and reducing overall device area while maintaining electrical functionality
2Ease of manufacture
If the emitter region is formed without self-alignment, then manufacturing process is simpler, but variation in emitter region size increases causing device characteristic variation
Solution Approach 1:
The invention performs preliminary action by forming the emitter region in a self-aligning manner during the manufacturing process. The emitter region is formed to automatically align with the base high concentration impurity region through the polycrystalline silicon structure, ensuring precise positioning and consistent dimensions before subsequent manufacturing steps are completed
Solution Approach 2:
The invention implements self-service through self-alignment mechanisms where the emitter region formation process inherently positions itself relative to the base region. The polycrystalline silicon structure and doping process work together to automatically establish the correct spatial relationship between emitter and base regions without requiring additional alignment steps, thereby ensuring manufacturing precision
Data Source
AI summary
A bipolar transistor for semiconductor device has a collector region having a first conductivity type disposed on a surface of a semiconductor substrate having the first conductivity type. A base region having a second conductivity type is disposed in the collector region. An emitter region having the first conductivity type is disposed in the base region. A high concentration first conductivity type region for a collector electrode is disposed in the collector region. A high concentration second conductivity type region for a base electrode is disposed in the base region. The high concentration first conductivity type region for a collector electrode and the high concentration second conductivity type region for a base electrode contact directly with each other so that the collector region and the base region have a same potential.