3D Memory Bonding Pad Structure for Reliable Capping-Layer Penetration
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Solution Overview
Problem
The integration of two-dimensional nonvolatile memory devices is limited, leading to the development of three-dimensional nonvolatile memory devices, which require innovative structures and manufacturing methods to enhance reliability.
Innovation Solution
A three-dimensional semiconductor memory device is proposed, featuring a plurality of micro pattern lines, a capping layer, and bonding pads that penetrate the capping layer to be coupled with the micro pattern lines. The bonding pads have a specific structure with a first portion electrically and mechanically coupled to the micro pattern lines and a second portion exposed externally with a convex shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If three-dimensional nonvolatile memory device structure is adopted to overcome integration limits, then integration density is improved, but manufacturing complexity increases
Solution Approach 1:
The bonding pad is divided into multiple portions (first portion, second portion, third portion) with different functions and structures. Each portion is formed through separate manufacturing steps, allowing optimized processing for each segment while maintaining overall integration density improvements from the 3D structure.
Solution Approach 2:
The bonding pad structure extends in multiple dimensions with portions at different depths and lateral positions. The first portion is at a first level, the second portion at a second level, and the third portion laterally extended, creating a multi-dimensional structure that increases integration density while managing manufacturing complexity through systematic formation steps.
2Reliability
If bonding pad structure penetrates capping layer to improve electrical connection, then electrical conductivity is improved, but mechanical reliability may worsen
Solution Approach 1:
The bonding pad structure is nested within the capping layer rather than simply penetrating it. The first portion is embedded in the capping layer, the second portion penetrates through, and the third portion is laterally extended, creating a nested configuration that maintains both electrical connection reliability and mechanical strength by distributing stress across multiple embedded and surface-level components.
Solution Approach 2:
The second portion of the bonding pad has a convex shape that protrudes from the capping layer surface. This curved, dome-like structure distributes mechanical stress more evenly compared to a sharp protrusion, maintaining mechanical strength while providing reliable electrical connection through the penetrated capping layer.
3Ease of operation
If convex shape is added to bonding pad to improve external coupling, then ease of operation is improved, but manufacturing precision requirements increase
Solution Approach 1:
The convex shape of the second portion is formed during the initial bonding pad formation process through selective deposition and etching steps, rather than requiring post-fabrication shaping. This preliminary formation of the convex geometry integrates it into the standard manufacturing flow, reducing the need for additional high-precision shaping operations.
Solution Approach 2:
The convex shape parameters (height, width, curvature radius) are optimized within specific ranges to provide adequate external coupling ease while remaining compatible with standard manufacturing capabilities. By controlling the convex portion's dimensions within practical limits, the design achieves improved operability without demanding excessive manufacturing precision beyond conventional capabilities.
Data Source
AI summary
A memory chip includes a plurality of micro pattern lines, a capping layer covering portions of the micro pattern lines. A bonding pad penetrates the capping layer and is coupled to one of the micro pattern lines. The bonding pad includes a first pad portion coupled to the associated micro pattern line and a second pad portion coupled to the first pad portion and exposed to a top surface of the memory chip. An upper surface of the second pad portion has a convex shape.