Via Interconnect Structure With Conductive Protection Against Undercut
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Solution Overview
Problem
The existing semiconductor manufacturing process faces challenges in forming reliable vertical electrical connections due to undercuts in conductive structures caused by acidic cleaning processes, leading to voids and increased current density, which can result in open circuits.
Innovation Solution
A conductive protection structure is formed over the lower metallization structure before cleaning, preventing undercuts and ensuring complete filling of via holes with conductive material, thereby maintaining the integrity of the electrical connection path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an acidic cleaning process is used to remove residuals from the via hole, then cleaning effectiveness is improved, but undercuts are formed in the lower conductive structure
Solution Approach 1:
A conductive protection structure is introduced as an intermediary layer between the acidic cleaning solution and the lower conductive structure. This protection structure is resistant to the acidic cleaning solution, allowing effective removal of organic residuals while preventing the acid from etching the lower conductive structure, thus avoiding undercut formation.
Solution Approach 2:
The conductive protection structure is formed in advance before the acidic cleaning process. This preliminary protective layer is deposited over the lower conductive structure to preemptively shield it from the harmful effects of the subsequent acidic cleaning, ensuring the lower conductive structure remains intact during cleaning.
2Ease of manufacture
If undercuts are present in the lower conductive structure, then cleaning can be performed, but voids are formed during metallization filling
Solution Approach 1:
The conductive protection structure serves as a mediator that prevents the acidic cleaning solution from creating undercuts. By blocking the acid from contacting the lower conductive structure, the protection structure ensures that the via hole walls remain vertical and free of undercuts, enabling complete filling during metallization without void formation.
Solution Approach 2:
The conductive protection structure provides beforehand cushioning by creating a protective barrier that absorbs or resists the acidic cleaning solution. This pre-established protection prevents the formation of undercuts that would otherwise lead to voids during subsequent filling processes, ensuring reliable electrical connections.
3Productivity
If voids are formed in the via hole, then manufacturing is simplified, but current density increases and open circuits may occur
Solution Approach 1:
The conductive protection structure acts as an intermediary that prevents undercut formation, which in turn prevents void formation during metallization filling. This ensures complete, void-free filling of the via hole, maintaining reliable electrical connections and preventing open circuits while allowing straightforward manufacturing processes.
Solution Approach 2:
By forming the conductive protection structure in advance, the patent preemptively prevents the conditions that lead to void formation. This preliminary protective measure ensures that subsequent filling processes produce void-free via structures, guaranteeing reliable electrical connections without compromising manufacturing simplicity.
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
This approach prevents voids and ensures reliable electrical connections by protecting the metallization structure from acidic etching, maintaining the structural integrity and reducing the risk of open circuits.
Implementation Method 1
a cleaning process, which is typically based on an acid solution, may cause one or more undercuts in the lower conductive structure
Data Source
AI summary
A method includes: forming a first conductive structure in a first dielectric layer; forming a conductive protection structure that is coupled to at least part of the first conductive structure; forming a second dielectric layer over the first dielectric layer; forming a via hole extending through at least part of the second dielectric layer to expose a portion of the conductive protection structure; cleaning the via hole; and refilling the via hole with a conductive material to form a via structure.