Semiconductor Memory Device Dummy Contact Etching
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Solution Overview
Problem
The existing semiconductor memory devices face reliability issues due to the accumulation of polymer during the etching process, which can block the opening of holes for contacts, leading to electrical coupling failures and degraded performance.
Innovation Solution
The introduction of dummy contacts adjacent to the main contacts during the etching process increases the hole pattern density, preventing excessive polymer accumulation and ensuring smooth etchant flow, thereby maintaining the integrity of the contact openings and enhancing device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contacts are formed by etching through dielectric layers, then electrical coupling between wiring lines is achieved, but polymer accumulation during etching blocks contact hole openings
Solution Approach 1:
The patent introduces dummy contacts adjacent to the main contact before the etching process. These dummy contacts serve as preliminary structures that modify the etching environment, preventing polymer accumulation from blocking the main contact hole opening. The dummy contacts are formed in advance to create a favorable etching pattern density.
Solution Approach 2:
The dummy contacts act as intermediary structures that mediate between the etching process and the main contact. By introducing these intermediate elements, the patent modifies the etchant flow dynamics and polymer deposition patterns, preventing the harmful blocking effect while maintaining the electrical coupling function of the main contact.
2Reliability
If hole pattern density is low during etching, then etchant flow is smooth, but polymer accumulates excessively and blocks openings
Solution Approach 1:
The dummy contacts are introduced in advance to modify the hole pattern density before etching. By having additional contact holes adjacent to the main contact, the pattern density increases, which prevents excessive polymer accumulation during the etching process while maintaining smooth etchant flow.
Solution Approach 2:
The patent changes the hole pattern density parameter by introducing dummy contacts. This parameter change from low to high density modifies the etching dynamics, reducing polymer accumulation and preventing contact hole blocking while maintaining etchant flow smoothness.
3Productivity
If three-dimensional structure is used to improve degree of integration, then memory cell density increases, but contact formation complexity increases
Solution Approach 1:
The dummy contacts are formed as preliminary structures during the contact formation process in three-dimensional memory devices. This preliminary action simplifies the overall process by preventing defects that would require rework, thereby managing the complexity of contact formation in high-density three-dimensional structures.
Solution Approach 2:
The dummy contacts are essentially copies of the main contact structure, replicated adjacent to it. This copying approach allows the use of the same formation process for both main and dummy contacts, simplifying the manufacturing process while preventing polymer blocking in the main contact.
Data Source
AI summary
A semiconductor memory device includes a peripheral circuit region including a first substrate, a peripheral circuit element disposed at least partially over the first substrate, a first dielectric layer covering the peripheral circuit element and a bottom wiring line disposed in the first dielectric layer and electrically coupled to the peripheral circuit element; a cell region including a second substrate disposed over the first dielectric layer, a memory cell array disposed over the second substrate; a second dielectric layer covering the memory cell array; a contact coupled to the bottom wiring line by passing through the second dielectric layer and the first dielectric layer in a first direction perpendicular to a top surface of the second substrate; and at least one dummy contact disposed adjacent to the contact in the second dielectric layer.