Conductive Feature Formation With Two-Step Etch Void Prevention
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Solution Overview
Problem
The semiconductor industry faces challenges in forming conductive features, particularly in small technology nodes, where voids in conductive materials can lead to higher resistance or failure due to constriction at the upper regions of openings caused by residues and byproducts during the etching process.
Innovation Solution
A method involving the formation of a barrier layer and adhesion layer in openings, followed by a two-step etching process to remove residues and smooth the upper portions of these layers, allowing for the deposition of conductive material without voids, ensuring proper contact and reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional single-step etching process is used to form openings, then the process is simple and fast, but residues and byproducts cause constriction at the upper regions of openings leading to voids in conductive material
Solution Approach 1:
The etching process is divided into two distinct steps: a first etching step that forms the opening and a second etching step that removes residues and byproducts. This segmentation allows each step to be optimized independently - the first step focuses on formation speed while the second step focuses on cleaning and precision, thereby resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The second etching step is performed as a preliminary action before depositing the conductive material. This preliminary cleaning action removes potential contaminants that would cause voids, ensuring that the subsequent conductive material deposition occurs on a clean surface, thus preventing defects before they occur.
2Reliability
If barrier layer and adhesion layer are formed thick to ensure coverage, then reliability is improved, but voids form in conductive material due to constriction
Solution Approach 1:
The residues and byproducts that initially cause harm (constriction and voids) are converted into a controlled removal process. The second etching step specifically targets and removes these harmful residues, transforming the problem of contamination into a controlled cleaning operation that actually enhances the quality of the conductive feature formation.
Solution Approach 2:
The two-step etching process is performed as a preliminary action before conductive material deposition. This ensures that the opening is completely clean and free of constrictions before the conductive material is deposited, allowing for uniform coverage and eliminating voids while maintaining proper layer thickness for reliability.
3Productivity
If geometry size is scaled down to increase functional density, then production efficiency is improved, but voids and conduction failures increase due to process challenges
Solution Approach 1:
The segmented two-step etching process allows for precise control at each stage, which is critical when working with scaled-down geometries. The first step creates the opening with appropriate dimensions for high-density packaging, while the second step ensures complete cleanliness, preventing voids that would be particularly problematic at smaller scales where tolerances are tighter.
Solution Approach 2:
The preliminary cleaning action of the second etching step is especially important for scaled-down geometries where even minor residues can cause significant constrictions. By performing this cleaning action before conductive material deposition, the process ensures reliable conduction paths even in the smallest features, maintaining reliability while benefiting from the high functional density enabled by scaling.
Data Source
AI summary
Generally, the present disclosure provides example embodiments relating to conductive features, such as metal contacts, vias, lines, etc., and methods for forming those conductive features. In an embodiment, a barrier layer is formed along a sidewall. A portion of the barrier layer along the sidewall is etched back. After etching back the portion of the barrier layer, an upper portion of the barrier layer along the sidewall is smoothed. A conductive material is formed along the barrier layer and over the smoothed upper portion of the barrier layer.