Segmented Gate Contact Plug for Thick Gate Stack Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor devices, particularly DRAM devices, the etching process for forming contact plugs is challenging when the second conductive pattern has a large thickness, as it complicates the exposure of the underlying first conductive pattern, leading to difficulties in electrical signal transfer and increased contact resistance.
Innovation Solution
The semiconductor device incorporates a contact plug design with specific extension and protrusion portions that contact the gate structure, including a first extension portion with a greater angle than the second extension portion, allowing increased contact area and reduced resistance, and a protrusion portion that does not contact the first conductive pattern, optimizing the etching process and signal transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second conductive pattern has a large thickness, then the gate structure can provide sufficient electrical conductivity and signal transfer capability, but the etching process to expose the first conductive pattern becomes difficult and contact resistance increases
Solution Approach 1:
The contact plug is segmented into multiple portions: a first extension portion that contacts the sidewalls of the gate mask and second conductive pattern, a second extension portion that contacts the first conductive pattern, and a protrusion portion. This segmentation allows the contact plug to establish electrical connection through different paths, bypassing the difficulty of etching through the thick second conductive pattern while maintaining reliable signal transfer.
Solution Approach 2:
The contact plug extends in multiple spatial dimensions with specific angular relationships. The first extension portion has a sidewall angle greater than the second extension portion, creating a three-dimensional configuration that contacts the gate structure at multiple levels and positions, thereby establishing electrical connection without requiring complete etching through the thick second conductive pattern.
2Reliability
If the contact plug etching is performed to expose the first conductive pattern, then electrical connection can be established, but the process complexity and contact resistance increase when the second conductive pattern is thick
Solution Approach 1:
The contact plug is divided into functional segments that establish electrical connection through different mechanisms. The first extension portion contacts the sidewalls of upper layers, the second extension portion contacts the first conductive pattern, and the protrusion portion provides additional connection path. This segmentation reduces etching complexity by creating multiple potential connection paths rather than requiring a single deep etch through the thick second conductive pattern.
Solution Approach 2:
The sidewalls of the gate mask and second conductive pattern serve as intermediary contact surfaces. The first extension portion of the contact plug contacts these sidewalls, providing an intermediate electrical connection path that bypasses the need to completely etch through the thick second conductive pattern, thereby simplifying the manufacturing process while maintaining electrical connection.
3Ease of manufacture
If the contact plug has a simple structure, then manufacturing is easier, but the contact area with the gate structure is insufficient leading to higher contact resistance
Solution Approach 1:
The contact plug is segmented into multiple portions (first extension portion, second extension portion, and protrusion portion), each contacting different surfaces of the gate structure. This segmentation increases the total contact area and provides multiple parallel electrical conduction paths, reducing contact resistance while maintaining a fabrication process that builds upon standard patterning and deposition techniques.
Solution Approach 2:
The contact plug utilizes three-dimensional spatial configuration with varying sidewall angles to maximize contact area. The first extension portion contacts sidewalls at a greater angle, while the second extension portion contacts at a smaller angle, creating a multi-faceted contact interface that increases electrical connection area without significantly complicating the manufacturing process.
Data Source
AI summary
A semiconductor device includes a gate structure and a contact plug. The gate structure extends in a first direction parallel to the substrate, and includes a first conductive pattern, a second conductive pattern and a gate mask sequentially stacked. The contact plug contacts an end portion in the first direction of the gate structure, and includes a first extension portion extending in a vertical direction and contacting sidewalls of the gate mask and the second conductive pattern, a second extension portion under and contacting the first extension portion and a sidewall of the first conductive pattern, and a protrusion portion under and contacting the second extension portion. A bottom of the protrusion portion does not contact the first conductive pattern. A first slope of a sidewall of the first extension portion is greater than a second slope of a sidewall of the second extension portion.