Semiconductor Contact Fabrication via Segmented Wet Etching
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Solution Overview
Problem
Highly integrated semiconductor devices face misalignment issues due to varying etch rates between film materials in existing Self-Aligned Contact (SAC) processes, affecting the reliability of contact formation.
Innovation Solution
A method for fabricating semiconductor devices involves forming transistors with gate structures and source/drain regions, depositing insulating films, and using a mask film pattern to create trenches with specific width ratios, allowing for the formation of conductive contacts with a bottom width larger than the top width to prevent open-circuit failures and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing SAC processes are used with varying etch rates between film materials, then contact holes can be formed, but misalignment occurs affecting reliability
Solution Approach 1:
The contact formation process is divided into multiple stages: first forming trenches through the oxide film to expose source/drain regions, then forming conductive plugs in these trenches, and finally removing the oxide film to form contact holes. This segmentation allows each step to be optimized independently, preventing misalignment issues that occur when attempting to form contact holes directly through varying etch rates.
Solution Approach 2:
The oxide film is removed selectively after conductive plugs are already formed in place. This preliminary formation of plugs before complete oxide removal ensures that the conductive material is positioned accurately before the final contact hole formation, preventing misalignment that would occur if all etching were done in one step.
2Reliability
If conventional contact formation methods are used, then contacts can be formed, but open-circuit failures and defects occur
Solution Approach 1:
Oxide film is retained around the conductive plugs during the plug formation process, serving as a protective cushion that prevents open-circuit failures. This remaining oxide acts as a barrier against defects and ensures reliable electrical connectivity by protecting the conductive plugs until the final contact hole formation step.
3Reliability
If standard trench formation is used, then contacts can be formed, but contact area is limited
Solution Approach 1:
Instead of forming contact holes directly through etching, the method inverts the approach by first forming conductive plugs in trenches, then removing oxide to create contact holes that expose these plugs. This inversion allows the contact area to be defined by the plug dimensions rather than being limited by etch hole geometry, enabling larger contact areas for improved electrical connectivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method improves the reliability of semiconductor devices by preventing open-circuit failures and reducing defects in conductive contacts, ensuring better electrical connectivity and increased contact area.
Implementation Method 1
forming a mask film pattern on the oxide film. The mask film pattern includes a first pattern having a first width and a second pattern having a second width different from the first width, removing a part of the oxide film using the mask film pattern to form first and second trenches
Data Source
AI summary
A method for fabricating a semiconductor device is provided. The method for fabricating a semiconductor device includes forming transistors on a semiconductor substrate, each of the transistors having a gate structure and source/drain regions, forming an oxide film on the transistors, forming a mask film pattern on the oxide film, the mask film pattern comprising a first pattern having a first width and a second pattern having a second width different from the first width, removing a part of the oxide film using the mask film pattern to form first and second trenches, filling the first and second trenches with a nitride film, removing the rest part of the oxide film to form third and fourth trenches, and forming conductive contacts by filling the third and fourth trenches. A top width of each of the third trenches is equal to the first width, and a top width of each of the fourth trenches is equal to the second width.