BiCMOS Bipolar Transistor Emitter Beta via Dual Implant Energy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The formation of bipolar transistors in BiCMOS semiconductor chips often results in low beta values due to mismatched dopant concentrations and implant energies used for both bipolar and MOS semiconductor regions, leading to suboptimal performance.
Innovation Solution
A method that simultaneously forms shallow base and emitter wells for bipolar transistors and source/drain regions for MOS transistors using specific dopant concentrations and implant energies, allowing for increased beta values by optimizing the formation of p+ and n+ emitter regions and source/drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same patterned photoresist layer is used to simultaneously form bipolar and MOS semiconductor regions, then fabrication costs are reduced, but the beta values of bipolar transistors become very low
Solution Approach 1:
The patent divides the semiconductor fabrication process into separate implantation steps for bipolar and MOS regions. Specifically, it forms bipolar semiconductor regions in a first implantation step and MOS semiconductor regions in a second implantation step, allowing each region type to receive optimized dopant concentrations and implant energies independently, thereby resolving the contradiction between cost reduction and performance maintenance
Solution Approach 2:
The patent applies different dopant concentrations and implant energies to different semiconductor regions based on their specific requirements. Bipolar regions receive one set of implantation parameters optimized for high beta values, while MOS regions receive another set optimized for their performance characteristics, enabling each region to have locally optimized properties
2Reliability
If ideal dopant concentration and implant energy for bipolar regions are used, then beta values increase, but the same parameters cannot be used for MOS regions
Solution Approach 1:
The patent segments the ion implantation process into distinct steps for bipolar and MOS regions. The first implantation step uses parameters optimized for bipolar regions to achieve high beta values, while the second implantation step uses different parameters optimized for MOS regions, allowing each device type to receive its ideal parameters without compromise
Solution Approach 2:
The patent performs preliminary formation of bipolar semiconductor regions with optimized implantation parameters before forming MOS semiconductor regions. This preliminary action ensures that bipolar regions achieve their target beta values before the fabrication process proceeds to MOS region formation with different parameters
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 beta values of bipolar transistors by optimizing the dopant distribution and implant energies, improving the overall performance of BiCMOS semiconductor chips.
Implementation Method 1
implanting dopants into the semiconductor material through openings in the patterned photoresist layer
Data Source
AI summary
The betas of the bipolar transistors in a BiCMOS semiconductor structure are increased by forming the emitters of the bipolar transistors with two implants: a source-drain implant that forms a first emitter region at the same time that the source and drain regions are formed, and an additional implant that forms a second emitter region at the same time that another region is formed. The additional implant has an implant energy that is greater than the implant energy of the source-drain implant.