Stepped Contact Hole Structure to Prevent Plug Voids
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Solution Overview
Problem
As semiconductor devices are miniaturized, there is a concern that voids are formed in contact plugs within contact holes, which existing techniques fail to adequately prevent.
Innovation Solution
A semiconductor device design that includes a semiconductor substrate with trenches, an interlayer insulating film, a contact hole with a stepped side wall, and an electrode connected to a semiconductor mesa portion through the contact hole, effectively preventing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the contact hole size is reduced to accommodate device miniaturization, then the device size is reduced, but voids are formed in the contact plug
Solution Approach 1:
The contact hole side wall is divided into multiple surfaces with different orientations (first side wall surface and second side wall surface) forming steps, which segments the continuous side wall into discrete facets that prevent void formation during electrode material deposition
Solution Approach 2:
The contact hole geometry transitions from a simple cylindrical shape to a stepped structure with multiple dimensional levels, where the side wall includes both vertical and inclined surfaces at different heights, creating a three-dimensional stepped profile that eliminates voids
2Manufacturing precision
If self-alignment method is used to form contact holes, then manufacturing precision is improved, but void formation in miniaturized contacts cannot be prevented
Solution Approach 1:
Different portions of the contact hole side wall are given different geometric properties - the first side wall surface has a specific orientation while the second side wall surface has a different orientation, creating local geometric variations that prevent void formation in specific problematic regions
Data Source
AI summary
A semiconductor device includes a semiconductor substrate on which a plurality of trenches are formed, an interlayer insulating film formed on the semiconductor substrate, a contact hole made in the interlayer insulating film, and an electrode connected to a semiconductor mesa portion that is a portion between the trenches of the semiconductor substrate through the contact hole. A side wall of the contact hole has a stepped shape having at least one step. A bottom of the contact hole is located on the semiconductor mesa portion, and an upper end of the contact hole is located outside the semiconductor mesa portion.