GAA Gate Cap Layer Layout to Prevent Source/Drain Shorts
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Solution Overview
Problem
As semiconductor devices continue to shrink in size, the manufacturing process becomes increasingly challenging, making it difficult to ensure the reliability of these devices.
Innovation Solution
The implementation of a gate-all-around (GAA) field-effect-transistor (FET) device structure, which includes the formation of an etch stop layer and a cap layer over a fin structure with sacrificial and channel layers, allows for the creation of a gate trench and the extension of an active gate structure around each channel layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor devices continue to shrink in size to increase functional density, then productivity and cost efficiency are improved, but manufacturing reliability deteriorates
Solution Approach 1:
An etch stop layer is formed over the fin structure before subsequent etching processes. This preliminary layer prevents unwanted etching of the fin structure during gate trench formation and other processing steps, ensuring structural integrity as devices scale down to smaller dimensions
Solution Approach 2:
The etch stop layer acts as an intermediary between the fin structure and the etching process. It selectively stops the etchant from damaging the fin structure while allowing controlled etching of other regions, thereby maintaining manufacturing reliability during scaling
2Volume of moving object
If feature sizes are reduced to create smaller components, then device density is improved, but manufacturing precision requirements worsen
Solution Approach 1:
The etch stop layer is deposited beforehand to establish a precise stopping point for etching operations. This preliminary structure enables accurate control of gate trench depth and prevents over-etching, which is critical when working with reduced feature sizes
Solution Approach 2:
The etch stop layer changes the etching parameter by providing a selective stopping point. Different materials in the structure etch at different rates, and the etch stop layer is specifically chosen to stop the etchant, enabling precise dimensional control at smaller scales
Data Source
AI summary
Semiconductor devices and methods for forming the semiconductor devices using a cap layer are provided. The semiconductor devices include a plurality of semiconductor layers vertically separated from one another, a gate structure that comprises a lower portion and an upper portion, wherein the lower portion wraps around each of the plurality of semiconductor layers, and a gate spacer that extends along a sidewall of the upper portion of the gate structure. In some examples, a gap dimension measured between the gate spacer and an adjacent one of the plurality of semiconductor layers is sufficiently small such that the gate structure does not contact the source/drain structures. In some examples, the gate spacer and an adjacent one of the one or more semiconductor layers of the fin structure are separated by a cap layer.