Conductive Line Protection Layer Prevents Etching Undercut
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Solution Overview
Problem
Existing methods for forming conductive lines in semiconductor devices face issues such as undercut during etching and long cycle times, which degrade device performance and reliability.
Innovation Solution
A new wiring structure and method involving a chemical reaction to replace electroplating, using Sn formed by immersion to protect the conductive lines, with a protection layer encompassing the top surface and sidewalls to prevent undercut, and an underlying layer of Ni, Au, or Pt, and conductive lines made of gold or copper with patterned layers of Ti/Cu.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroplating is used to form conductive lines, then the wiring can be formed with good conductivity, but undercut is generated after etching processes which seriously degrades device performance
Solution Approach 1:
A protection layer comprising Sn (tin) is introduced as an intermediary substance between the conductive line and the etching environment. This protection layer is formed by immersion plating and serves as a mediator that prevents direct contact between the conductive line and etching solutions, thereby eliminating undercut while maintaining the conductive properties of the underlying metal layers
Solution Approach 2:
The protection layer is formed in advance before etching processes to preemptively counteract the harmful effects of etching. By applying the Sn protection layer prior to etching, the system prevents undercut from occurring in the first place, rather than attempting to correct it afterward
2Reliability
If conventional barrier structures with multiple layers are used, then diffusion prevention is achieved, but the cycle time is too long which degrades throughput
Solution Approach 1:
The invention uses composite material structures combining Ti/Cu patterned layers with Sn protection layers. This composite approach integrates diffusion barrier functionality (Ti) with high conductivity (Cu) and protection (Sn) in a streamlined configuration that achieves reliable diffusion prevention while reducing overall process cycle time compared to conventional multi-layer barriers
Solution Approach 2:
The invention changes the material parameter from conventional barrier materials to Sn-based protection layers formed by immersion plating. This parameter change allows for faster formation while maintaining effective diffusion prevention, thereby improving throughput without sacrificing reliability
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 enhances device reliability and performance by controlling dimension and line width, eliminating sidewall erosion, and reducing cycle time, while being cost-effective and compatible with existing facilities.
Implementation Method 1
A barrier layer is provided in order to prevent penetration of Cu into an undesired area
Implementation Method 2
The copper seed layer receives copper plating by electroplating
Implementation Method 3
a chemical Sn is formed by an immersion step, only to protect the wiring
Data Source
AI summary
The conductive line structure of a semiconductor device including a base; at least one patterned conductive layer formed over the base; a conductive line formed over the at least one patterned conductive layer; a protection layer that encompasses the top surface and sidewall of the conductive line to prevent undercut generated by etching. The structure further comprises an underlying layer under the conductive line. The underlying layer includes Ni, Cu or Pt. The conductive line includes gold or copper. The at least one patterned conductive layer includes at least Ti/Cu. The protection layer includes electro-less plating Sn, Au, Ag or Ni.