Self-Aligned Semiconductor Contacts via Raised Shallow Trench Isolation
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to reduce contact resistance and prevent shorts between source/drain diffusion regions and the gate, especially as device dimensions shrink, while simplifying the manufacturing process and lowering costs.
Innovation Solution
A semiconductor structure with self-aligned contacts and shallow trench isolations is developed, where the second shallow trench isolations have an upper surface higher than the source/drain regions, and contacts are formed self-aligned with the gate, eliminating the need for etching contact holes and using sidewall spacers to define contact holes, thereby reducing misalignment and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact dimension is scaled down to prevent short circuit, then short circuit risk is reduced, but contact resistance significantly increases
Solution Approach 1:
The patent introduces a third dimension by forming raised shallow trench isolation structures that extend above the source/drain region surfaces. This vertical dimension provides self-aligned contact definition without requiring lateral etching, enabling precise contact formation at scaled dimensions while maintaining low resistance through adequate contact area and proper material filling.
Solution Approach 2:
The raised shallow trench isolation structures serve multiple functions simultaneously: they define contact boundaries, provide self-alignment references, and eliminate the need for separate etching steps. The structure serves itself by using its own geometry to guide contact formation, reducing manufacturing complexity and improving precision at scaled dimensions.
2Ease of manufacture
If traditional etching process is used to form contact holes, then contact holes can be formed, but gate exposure and shorts may occur due to misalignment
Solution Approach 1:
The raised shallow trench isolation structures are formed beforehand to establish contact boundaries before contact material deposition. This preliminary structuring creates self-aligned boundaries that guide contact formation, eliminating the need for alignment-critical etching steps and preventing gate exposure through pre-defined contact regions.
Solution Approach 2:
The patent extracts the contact definition function from the etching process and transfers it to the raised shallow trench isolation structure geometry. By removing the etching step for contact hole formation, the source of misalignment and gate exposure is eliminated, while contact holes are defined by the pre-formed isolation structure boundaries.
3Manufacturing precision
If conventional manufacturing process is used, then standard contact formation is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The raised shallow trench isolation structures perform multiple functions: they provide electrical isolation, define contact boundaries, establish self-alignment references, and serve as etch stop layers. This multi-functionality consolidates several manufacturing requirements into a single structure, reducing overall process complexity while maintaining high alignment precision.
Solution Approach 2:
The patent merges the isolation function and contact definition function into a single raised shallow trench isolation structure. By combining these functions, the number of separate manufacturing steps is reduced, and the structure provides both isolation and alignment guidance simultaneously, simplifying the overall manufacturing process.
Data Source
AI summary
The present application discloses a semiconductor structure and a method for manufacturing the same. Compared with conventional approaches to form contacts, the present disclosure reduces contact resistance and avoids a short circuit between a gate and contact plugs, while simplifying manufacturing process, increasing integration density, and lowering manufacture cost. According to the manufacturing method of the present disclosure, second shallow trench isolations are formed with an upper surface higher than an upper surface of the source/drain regions. Regions defined by sidewall spacers of the gate, sidewall spacers of the second shallow trench isolations, and the upper surface of the source/drain regions are formed as contact holes. The contacts are formed by filling the contact holes with a conductive material. The method omits the steps of etching for providing the contact holes, which lowers manufacture cost. By forming the contacts self-aligned with the gate, the method avoids misalignment and improves performance of the device while reducing a footprint of the device and lowering manufacture cost of the device.