Semiconductor Wire Pad Structure for Enhanced Bonding Force
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Solution Overview
Problem
Semiconductor devices with Cu/low-k layers face issues with mechanical strength and bonding force due to weak low-k and SiCN barrier layers, leading to wire bonding deficiencies during electro-migration/stress-migration tests.
Innovation Solution
A wire pad structure for semiconductor devices is developed, including a low-k layer, oxide layer, undoped silicate glass (USG) film, nitride film, and TEOS films, with metal interconnects formed using a damascene process, enhancing wire bonding strength by forming these layers to specific thicknesses and compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu/low-k layer structure is used, then electrical performance is improved, but mechanical strength and bonding force deteriorate
Solution Approach 1:
The patent applies composite materials by creating a multi-layer wire pad structure comprising low-k layer, oxide layer, SiCN layer, nitride film, and TEOS film. Each layer contributes different properties: the low-k layer provides electrical performance, while the oxide, SiCN, nitride, and TEOS layers provide mechanical strength and bonding force. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both electrical performance and mechanical strength simultaneously.
2Reliability
If SiCN barrier layer is used, then electrical isolation is improved, but bonding force deteriorates
Solution Approach 1:
The patent uses a composite structure where the SiCN layer is combined with oxide layer, nitride film, and TEOS film. The SiCN layer provides electrical isolation, while the surrounding oxide, nitride, and TEOS layers provide bonding force. This composite approach allows the SiCN barrier layer to fulfill its electrical isolation function without being the sole source of mechanical strength, thus resolving the contradiction between electrical isolation and bonding force.
Solution Approach 2:
The patent applies local quality by assigning different functions to different layers: the SiCN layer specifically provides electrical isolation in its local region, while the oxide layer, nitride film, and TEOS film provide bonding force in their respective regions. This functional differentiation allows each layer to optimize its local property without compromising the overall structure, resolving the contradiction between electrical isolation and bonding force.
3Reliability
If low-k layer thickness is increased, then electrical performance is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent resolves this contradiction by creating a composite structure where the low-k layer is combined with oxide layer, SiCN layer, nitride film, and TEOS film. The low-k layer can be optimized for electrical performance while the surrounding layers (particularly the nitride film and TEOS film) provide mechanical strength. This composite approach allows independent optimization of electrical and mechanical properties through layer thickness adjustment.
Data Source
AI summary
A semiconductor device includes a low-k layer formed over a semiconductor device; a first TEOS film formed over the low-k layer; a SiCN layer formed over the first TEOS film; an undoped silicate glass film formed over the SiCN layer; a nitride film formed over the USG film; a second TEOS film formed over the nitride film; a first metal interconnect extending from the low-k layer to the undoped silicate glass film; and a second metal interconnect extending from the nitride film to the second TEOS film, wherein the first metal interconnect and the second metal interconnect are electrically connected and a wire is bonded to the second metal interconnect.