Flexible Conductive Contacts for ECMP Wafer Planarization
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Solution Overview
Problem
Conventional electrochemical mechanical planarization (ECMP) systems face issues with flexible, conductive contacts that are not inert under ECMP conditions, leading to corrosion and damage to semiconductor wafers, and existing electrical contact schemes apply excessive force, limiting metal removal and causing structural damage.
Innovation Solution
A flexible, conductive contact system using a thin layer of inert noble metal, such as gold, deposited on a flexible insulative material like KAPTON or MYLAR, with a conductive structure that maintains electrical conductivity while being thermally formed to ensure flexibility and reduce wear, integrated into the ECMP apparatus to provide controlled planarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flexible, conductive contacts are used in ECMP systems, then electrical conductivity is achieved, but the contacts corrode under ECMP conditions and damage semiconductor wafers
Solution Approach 1:
The contact is constructed as a composite structure with a flexible insulative core material (such as polyimide or elastomer) and an outer coating of inert noble metal (such as gold, platinum, or rhodium). This composite structure combines the flexibility and conformability of the insulative material with the corrosion resistance and electrical conductivity of the noble metal coating, resolving the contradiction between achieving conductivity and preventing corrosion/damage.
2Force
If stiff electrical contacts are used to apply sufficient force for planarization, then contact pressure is adequate, but the contacts exert excessive force that limits metal removal and causes structural damage to the wafer
Solution Approach 1:
The contact employs a flexible insulative material (such as polyimide or elastomer) that can deform and conform to the wafer surface topology. This flexibility allows the contact to apply distributed pressure across the wafer surface without concentrating excessive force at discrete points, thereby achieving adequate contact pressure for planarization while preventing structural damage to fragile wafer features.
3Force
If small electrical contacts are used to reduce forces on the wafer, then mechanical stress is reduced, but the contacts can only contact the wafer edge and create terminal effects that limit metal removal
Solution Approach 1:
The contact system transitions from static, discrete point contacts to a dynamic, distributed flexible surface that can adapt its contact area. The flexible insulative material allows the contact to conform to the wafer surface and maintain appropriate pressure distribution across a larger area, enabling effective metal removal from central regions without exerting excessive localized stress that would damage the wafer.
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
The solution reduces mechanical stress on wafers, minimizes contact wear, and allows for controlled metal removal with reduced risk of damage, enhancing the integrity and planarity of semiconductor surfaces.
Implementation Method 1
A conductive material is deposited on the first surface and second surface
Implementation Method 2
The flexible layer is subjected to thermal forming, which results in the first surface of the flexible layer disposed in a first plane and the second surface of the flexible layer disposed in a second plane that is remote from and parallel to the first plane
Implementation Method 3
In ECMP, metal removal is accomplished by electrolysis rather than by the corrosive action of a slurry
Data Source
AI summary
Conductive contacts and methods for fabricating conductive contacts for electrochemical mechanical planarization are provided. A conductive contact in accordance with an exemplary embodiment of the invention includes, but is not limited to, a first conductive surface formed of a flexible material, a conductive element that is disposed remote from the first conductive surface and that is configured for electrical coupling to an external circuit, and an intermediate portion that electrically couples the first conductive surface and the conductive element.