Self-Aligned Spacer Transistor Fabrication
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Solution Overview
Problem
Conventional methods for fabricating CMOS transistors require a large area for isolation, increasing the fabricating cost and process complexity due to the need for extensive space to isolate N channel and P channel transistors and their respective contacts.
Innovation Solution
A method involving the formation of a spacer surrounding a first device area on a substrate, with a second device area isolated from the first by the spacer, allowing for self-aligned transistor structure creation, thereby reducing the overall area required and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional isolation technology (STI, LOCOS, SWAMI) is used to isolate N channel and P channel transistors, then transistor isolation is achieved, but a relatively large area is required and fabricating cost increases
Solution Approach 1:
The spacer structure serves dual purposes: it acts as an isolation barrier between N channel and P channel transistors, and simultaneously functions as a self-aligned mask for defining device areas. This self-service approach eliminates the need for separate isolation structures, reducing the total area required while maintaining effective transistor isolation.
Solution Approach 2:
The spacer is designed to perform multiple functions: electrical isolation between transistors, physical separation of device areas, and alignment reference for subsequent processing steps. By consolidating these functions into a single structure, the patent reduces the overall area required compared to conventional multi-structure isolation approaches.
2Reliability
If conventional isolation technology is used, then transistor isolation is achieved, but process complexity and fabricating cost increase
Solution Approach 1:
The spacer structure serves dual purposes: it acts as an isolation barrier between N channel and P channel transistors, and simultaneously functions as a self-aligned mask for defining device areas. This self-service approach eliminates the need for separate isolation structures, reducing the total area required while maintaining effective transistor isolation.
Solution Approach 2:
The patent combines the isolation function and alignment mask function into a single spacer structure. This merging of functions simplifies the fabrication process by reducing the number of separate structures that need to be created and aligned, thereby reducing process complexity and fabricating cost.
3Reliability
If ultra thin SOI blanket wafer is used to address short channel effect, then transistor performance is improved, but fabricating cost increases
Solution Approach 1:
Instead of using expensive ultra thin SOI blanket wafer for the entire substrate, the patent applies the thin SOI layer only in the specific device areas where transistors are located. The spacer-defined device areas allow precise localization of the thin SOI region, achieving the necessary transistor performance while significantly reducing the overall material cost compared to blanket wafer approaches.
Data Source
AI summary
A transistor, a method for fabricating a transistor, and a semiconductor device comprising the transistor are disclosed in the present invention. The method for fabricating a transistor may comprise: providing a substrate and forming a first insulating layer on the substrate; defining a first device area on the first insulating layer; forming a spacer surrounding the first device area on the first insulating layer; defining a second device area on the first insulating layer, wherein the second device area is isolated from the first device area by the spacer; and forming transistor structures in the first and second device area, respectively. The method for fabricating a transistor of the present invention greatly reduces the space required for isolation, significantly decreases the process complexity, and greatly reduces fabricating cost.