Bipolar Transistor Collector Resistance Reduction via Depth Segmentation
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Solution Overview
Problem
Existing semiconductor devices face challenges in reducing collector resistance in bipolar transistors while maintaining high breakdown voltage between the emitter and collector, as increasing N-type impurity concentration can lead to reduced breakdown voltage and potential short-circuiting due to inaccurate impurity distribution control during manufacturing.
Innovation Solution
A semiconductor device with a bipolar transistor structure where the collector region is formed with a shallow trench isolation structure, and ion implantation is performed at an angle orthogonal to the main surface to create a high concentration collector leading portion, allowing for reduced collector resistance without lowering the breakdown voltage by varying the formation depth of the collector region between locations below the STI structure and active regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the implantation amount of N-type impurity is increased to reduce collector resistance, then collector resistance is reduced, but the concentration of N-type impurity near the base region increases and breakdown voltage BVceo is lowered
Solution Approach 1:
The patent applies local quality by creating different impurity concentration profiles in different regions of the collector. Specifically, the collector has a first region with high N-type impurity concentration to reduce resistance, and a second region near the base interface with lower impurity concentration to maintain breakdown voltage. This spatial variation in impurity concentration allows simultaneous optimization of both conductivity and voltage breakdown characteristics.
Solution Approach 2:
The collector region is segmented into multiple zones with different impurity concentrations. The patent divides the collector into a high-concentration region (first region) for current conduction and a low-concentration region (second region) near the base interface for voltage breakdown. This segmentation enables independent optimization of resistance and breakdown voltage in different spatial zones.
2Reliability
If the collector leading portion is formed at a deep location to reduce collector resistance, then collector resistance is reduced, but the collector leading portion becomes enlarged in the lateral direction and may cause short-circuiting between emitter and collector
Solution Approach 1:
The patent changes the depth parameter of the collector leading portion to optimize resistance while preventing short-circuits. By controlling the implantation depth and concentration profile, the collector leading portion is positioned at an optimal depth that provides low resistance paths without excessive lateral enlargement. The impurity concentration gradient also helps confine the conductive region vertically, preventing lateral spread that could cause short-circuiting.
3Reliability
If a high concentration implantation layer is formed in a wide range at a deep location to reduce collector resistance, then collector resistance is reduced, but this may hinder the insulation isolation with the STI structure and cause short-circuiting
Solution Approach 1:
The patent applies local quality by restricting the high concentration implantation layer to specific regions rather than forming it uniformly across the entire collector. The high concentration layer is formed only in regions where it is needed for resistance reduction, while maintaining lower concentrations near the STI structure to preserve insulation isolation. This localized approach prevents short-circuiting while achieving the desired resistance reduction.
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 effectively reduces collector resistance while maintaining high breakdown voltage and preventing short-circuiting, with the collector region's depth difference below the STI structure and active regions optimized to achieve minimal resistance and maximum voltage retention.
Implementation Method 1
ion implantation is performed at an angle orthogonal to the main surface to create a high concentration collector leading portion
Data Source
AI summary
A semiconductor device including a bipolar transistor in which the collector resistance. The bipolar transistor includes a first conduction type semiconductor substrate having a main surface. A second conduction type collector region is formed in the semiconductor substrate. A shallow trench isolation structure isolates the main surface of the semiconductor substrate into two insulated active regions. A collector leading portion is formed in one of the active regions. A first conduction type base region and a second conduction type emitter region are formed on the other one of the active regions. The collector region has a first depth from the main surface immediately below the shallow trench isolation structure, and the collector region has a second depth from the main surface immediately below the two active regions. The first depth is less than the second depth.