Fin Structure Trench Depth Variation for Gate Control
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Solution Overview
Problem
Current semiconductor device fabrication techniques face challenges in minimizing development load and optimizing the structure of multi-gate transistors, particularly in managing protrusion structures to prevent defects and improve yield.
Innovation Solution
The semiconductor device incorporates fin structures with varying trench depths and protrusion structures at trench boundaries, where the protrusion structures protrude from the trench bottoms to a height lower than the field insulating layer, and are designed with inclined surfaces to manage their size and alignment for optimal gate placement and process compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protrusion structures are formed at trench boundaries in multi-gate transistor fabrication, then gate control capability is improved, but device complexity increases
Solution Approach 1:
The device is divided into multiple fins (first fin, second fin, third fin) with different trench depths, creating a segmented structure where each fin can be independently controlled. The protrusion structures are selectively formed at specific trench boundaries (between first and second trenches, and between second and third trenches) rather than uniformly across all trenches, reducing overall complexity while maintaining control capability.
Solution Approach 2:
Different regions of the device have different structural properties: the first trench has a first depth, the second trench has a second depth greater than the first, and the third trench has a third depth equal to the first. Protrusion structures are selectively placed at specific boundaries rather than uniformly, creating local variations in structure that optimize gate control where needed while simplifying other regions.
2Manufacturing precision
If multiple trenches with varying depths are formed to create protrusion structures, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The trenches are formed with predetermined depths in a specific sequence: first trenches are formed with a first depth, then second trenches are formed with a greater second depth, and third trenches are formed with a first depth again. This preliminary structuring of the trenches before forming protrusion structures simplifies the overall manufacturing process by establishing a template that guides subsequent steps.
Solution Approach 2:
The protrusion structures are formed within the trenches at specific boundaries, creating a nested arrangement where protrusions are contained within the trench structures. The protrusion structures protrude from the bottom of the second trench to a height lower than the field insulating layer, creating a hierarchical structure that simplifies alignment requirements.
3Productivity
If protrusion structures are formed to extend side by side with fin short sides, then device density is increased, but difficulty of detecting and measuring increases
Solution Approach 1:
The protrusion structures have asymmetric geometry with inclined surfaces: a first inclined surface on the side of the first trench with a first angle of inclination, and a second inclined surface on the side of the second trench with a second angle of inclination that is different from the first. This asymmetric design creates distinct measurement signatures that can be detected and characterized, reducing measurement difficulty while maintaining high density.
Data Source
AI summary
A semiconductor device and a method of fabricating the same are provided. The semiconductor device includes a fin which comprises long sides and a first short side, a first trench which is immediately adjacent the first short side of the fin and has a first depth, a second trench which is immediately adjacent the first trench and has a second depth greater than the first depth, a first protrusion structure which protrudes from a bottom of the first trench and extends side by side with the first short side, and a gate which is formed on the first protrusion structure to extend side by side with the first short side.