Stacked Via Contact Structure for High-Aspect-Ratio Defect Reduction
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Solution Overview
Problem
The increasing aspect ratio of vias in semiconductor devices due to downsizing leads to defects such as voids, seams, or grooves in via contacts, necessitating a solution to reduce these defects.
Innovation Solution
A method involving the formation of a first via contact feature, etching it back, and then forming a second via contact feature on the first, with intermediate steps including trench definition, glue layer formation, and pre-cleaning to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If via size is reduced to achieve further device scaling, then device density and integration are improved, but aspect ratio of via increases leading to defect formation
Solution Approach 1:
The via contact formation process is segmented into two distinct stages: first forming a contact feature extending to the conductive feature, then forming a via contact feature on top of it. This segmentation allows each stage to be optimized independently, preventing defects that would occur in a single-step process while maintaining the reduced via dimensions necessary for device scaling.
2Manufacturing precision
If aspect ratio of via is reduced to prevent defect formation, then via contact quality is improved, but device scaling and density are limited
Solution Approach 1:
The solution transitions from a single-dimensional via structure to a multi-dimensional stacked structure. By forming the via contact feature on top of the contact feature, the current is distributed across multiple horizontal layers rather than forcing current through a single high aspect ratio path, thus improving contact quality without limiting device scaling.
3Device complexity
If single-step via contact formation is used to simplify process, then manufacturing complexity is reduced, but defect formation increases
Solution Approach 1:
The contact feature is formed in advance before the via contact feature. This preliminary action creates a stable foundation that prevents defects during subsequent processing steps. The pre-formed contact feature with its adhesive layer ensures proper adhesion and electrical connectivity before the via contact feature is added, thereby improving reliability without significantly increasing overall process complexity.
Data Source
AI summary
A method for manufacturing a semiconductor device includes forming a conductive feature in a first dielectric layer; forming a second dielectric layer on the first dielectric layer; forming a trench that penetrates through the second dielectric layer, and terminates at the conductive feature; forming a contact layer in the trench and on the conductive feature; etching back the contact layer to form a first via contact feature in the trench, the first via contact feature being electrically connected to the conductive feature; and forming a second via contact feature on the first via contact feature in the trench.