BJT-CFET Integration Layout to Limit Dopant Outdiffusion
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Solution Overview
Problem
The challenge of integrating bipolar junction transistors (BJTs) with other devices in integrated circuits complicates semiconductor processing, especially when scaling devices to smaller nodes, and requires novel approaches to avoid dopant outdiffusion and outgassing during high-temperature processing.
Innovation Solution
A semiconductor device is fabricated with a BJT region, a complementary FET region, and a transition region, utilizing a composite structure with a dielectric material and avoiding high-temperature processing after doped layers are formed to reduce dopant outdiffusion and outgassing, and includes methods to form a gate electrode, collector, base, and emitter layers without compromising device integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-temperature processing is used during semiconductor fabrication, then device performance and material properties are improved, but dopant outdiffusion and outgassing occur causing device degradation
Solution Approach 1:
The patent forms the BJT doped layers (emitter, base, collector) before completing the FET gate processing. This preliminary formation of BJT structures allows the doping to be completed at lower temperatures before any high-temperature FET processing occurs, preventing dopant outdiffusion while still enabling subsequent high-temperature processing for FET gate formation and other device optimization steps
2Adaptability or versatility
If BJT structures are integrated with FET structures on the same substrate, then device functionality and circuit capabilities are enhanced, but processing complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the semiconductor substrate into distinct processing regions: a first region for BJT formation where doped layers are formed first, and a second region for FET formation where gate structures are formed first. This segmentation allows each device type to be processed independently with its own optimal sequence, reducing overall processing complexity while achieving successful integration
Solution Approach 2:
The patent performs preliminary formation of BJT doped layers in the first region before completing FET gate processing in the second region. This preliminary action establishes the BJT structures early in the process sequence, allowing subsequent FET processing to proceed without affecting the already-formed BJT doping, thereby simplifying the integrated processing flow
Data Source
AI summary
The present disclosure generally relates to semiconductor processing integration for a bipolar junction transistor (BJT). In an example, a semiconductor device includes a semiconductor substrate, a bipolar junction transistor (BJT), a field effect transistor (FET), and a composite structure. The semiconductor substrate includes a BJT region, a complementary FET (CFET) region, and a transition region between the BJT region and the CFET region. The BJT is on the semiconductor substrate in the BJT region. The FET is on the semiconductor substrate in the CFET region. The composite structure is on the semiconductor substrate in the transition region. The composite structure includes a dielectric material. The dielectric material has a sidewall proximate and facing the CFET region and has a top surface that forms at least a portion of an upper surface of the composite structure.