Backside Power Delivery for Bipolar-Logic Integration
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Solution Overview
Problem
Integrating bipolar junction transistors (BJTs) with logic circuits in semiconductor fabrication poses challenges such as substrate removal, thermal and mechanical effects, isolation, signal compatibility, power supply management, and comprehensive testing and validation.
Innovation Solution
A semiconductor device is developed that integrates BJTs with direct backside contact and accurate backside contact depth control, enabling the formation of a power delivery network (PSPDN) for bipolar devices co-integrated with logic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bipolar devices are integrated with logic circuits on the same substrate, then integration density is improved, but thermal management and electrical isolation become more difficult
Solution Approach 1:
The substrate is segmented into multiple regions with different doping types (N-type and P-type regions) to provide electrical isolation between bipolar devices and logic circuits. This segmentation allows high-density integration while maintaining proper electrical boundaries and thermal management zones.
Solution Approach 2:
An intermediate layer structure is introduced between the bipolar devices and logic circuits, including diffusion breaks and isolation regions. These intermediary elements act as thermal and electrical buffers, enabling close integration while preventing thermal runaway and electrical interference.
2Power
If backside contact is used for bipolar devices, then power delivery network efficiency is improved, but contact depth control precision deteriorates
Solution Approach 1:
The backside contact depth is predetermined and controlled during the fabrication process through precise etching and deposition steps. The contact holes are formed to specific depths before subsequent processing, ensuring accurate electrical connection to the bipolar device terminals while maintaining power delivery efficiency.
Solution Approach 2:
Traditional mechanical contact methods are replaced with semiconductor fabrication processes including photolithography, plasma etching, and atomic layer deposition. These process-controlled methods provide superior depth control precision compared to mechanical approaches, enabling accurate backside contact formation.
3Reliability
If diffusion breaks are introduced between source/drain regions, then electrical isolation is improved, but manufacturing complexity increases
Solution Approach 1:
The diffusion break formation is merged with existing source/drain region processing steps. The same ion implantation and thermal annealing processes used for source/drain formation are also applied to create diffusion breaks, eliminating the need for separate manufacturing steps and reducing overall complexity.
Solution Approach 2:
The diffusion breaks utilize self-aligned formation processes where the isolation regions are automatically positioned relative to source/drain regions through the fabrication sequence. This self-alignment mechanism reduces the need for additional lithography and alignment steps, simplifying manufacturing while ensuring proper electrical isolation.
Data Source
AI summary
A semiconductor device includes a bipolar device and a logic device adjacent the bipolar device. A backside of the bipolar device is connected to a backside interconnect. A frontside of the bipolar device is connected to a back end of line (BEOL).