Contact Hole Formation Using Protective Dielectric Layer
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Solution Overview
Problem
The existing method of forming contact holes in semiconductor fabrication is unstable, particularly due to the repetition process which can widen the first contact hole, leading to an undesired large diameter and potential short circuits.
Innovation Solution
The method involves forming a first contact hole and then creating a protective fourth dielectric layer over it, followed by forming a second contact hole, which prevents the diameter increase during subsequent etching processes, thereby enhancing the stability of the contact-hole formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a repetition process is performed to form contact holes, then the diameter of contact holes can be adjusted, but the first contact hole may be damaged and widened leading to instability
Solution Approach 1:
The patent applies preliminary action by forming a protective film over the first contact hole before performing the repetition process. This protective film is formed in advance to prevent damage to the first contact hole during subsequent etching operations, thereby maintaining process stability while still allowing diameter adjustment through the repetition process.
Solution Approach 2:
The protective film acts as an intermediary element between the first contact hole and the etching process. It mediates the interaction by providing protection during the repetition process, allowing the etching to proceed without directly damaging the first contact hole, thus resolving the contradiction between adjusting diameter and maintaining stability.
2Ease of manufacture
If the third dielectric layer is removed to access the first contact hole, then the first contact hole can be formed, but subsequent etching processes may widen it
Solution Approach 1:
The protective film is formed preliminarily over the first contact hole before any subsequent etching processes. This preliminary action ensures that when the third dielectric layer is removed and subsequent etching occurs, the first contact hole is already protected and will not be widened, maintaining diameter consistency while enabling easy manufacture.
Solution Approach 2:
The protective film provides beforehand cushioning by being formed in advance to absorb or prevent the harmful effect of subsequent etching processes on the first contact hole. This cushioning effect ensures that the first contact hole diameter remains consistent even though the third dielectric layer is removed and subsequent etching is performed.
3Productivity
If multiple etching processes are performed, then contact holes can be formed through multiple layers, but the first contact hole diameter increases
Solution Approach 1:
The protective film is formed preliminarily before the multiple etching processes begin. This preliminary protective layer remains in place during all subsequent etching operations, allowing productivity to improve through multi-layer contact hole formation while preventing the first contact hole diameter from increasing.
Solution Approach 2:
The protective film serves as an intermediary that allows multiple etching processes to occur without directly exposing the first contact hole to these processes. It mediates between the need for multi-layer formation (productivity) and the need to maintain first contact hole diameter precision.
Data Source
AI summary
A method of forming contact hole is disclosed, including the steps of: providing a semiconductor substrate having a first dielectric layer, a second dielectric layer and a third dielectric layer formed thereon in this order; forming a first contact hole through the third dielectric layer, the second dielectric layer and the first dielectric layer by using an etching process to expose the semiconductor substrate; removing the third dielectric layer; forming a fourth dielectric layer over the second dielectric layer, the fourth dielectric layer filling the first contact hole; forming a second contact hole through the fourth dielectric layer, the second dielectric layer and the first dielectric layer to expose the semiconductor substrate; and removing the fourth dielectric layer. The method is capable of improving the stability of the contact-hole formation process.