Amorphous Carbon Stop Layer for Tungsten Plug CMP
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Solution Overview
Problem
As semiconductor devices shrink, controlling chemical mechanical planarization (CMP) technology for tungsten plugs becomes challenging due to the thinness of TiN film and Ti barrier layers, leading to over-grinding and significant fluctuations in dielectric layer thickness, which reduces device stability and yield.
Innovation Solution
A method involving the use of an amorphous carbon layer as an etch stop layer, combined with a dielectric anti-reflectivity coating and a barrier layer, to protect the dielectric layer during CMP, ensuring precise tungsten plug formation and minimizing RC impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If TiN film and Ti barrier layer are made thinner to accommodate smaller device sizes, then device scaling is achieved, but CMP control becomes difficult leading to over-grinding and dielectric layer thickness fluctuations
Solution Approach 1:
An amorphous carbon layer is deposited on the dielectric layer before the CMP process. This layer serves as a sacrificial stop layer that protects the underlying dielectric layer from over-grinding during CMP, allowing the TiN and Ti barrier layers to be made thinner for device scaling while maintaining dielectric layer thickness control
Solution Approach 2:
The amorphous carbon layer acts as an intermediary between the CMP polishing head and the dielectric layer. It provides a uniform polishing surface with consistent mechanical properties, enabling precise control of the dielectric layer thickness while allowing thinner barrier layers for scaled devices
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If conventional CMP stop layers are used with thinner barrier layers, then device scaling is enabled, but over-grinding occurs reducing device stability and yield
Solution Approach 1:
The amorphous carbon layer is deposited in advance before CMP processing. This preliminary layer prevents direct contact between the CMP polishing head and the dielectric layer, eliminating over-grinding issues that would otherwise reduce device stability and yield when using thinner barrier layers
Solution Approach 2:
The amorphous carbon layer provides a cushioning effect during CMP, absorbing the mechanical stress and preventing excessive removal of the dielectric layer. This beforehand protection ensures device reliability is maintained even when barrier layers are thinned for scaling
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 method effectively prevents dielectric layer damage during CMP, stabilizes device performance, and enhances product yield by using an amorphous carbon layer as a stop layer, thereby improving the manufacturing process for tungsten plugs.
Implementation Method 1
the contact holes filled by tungsten and then processed by chemical mechanical planarization (CMP)
Implementation Method 2
amorphous carbon is typically used in the contact holes as a hard mask when etching
Implementation Method 3
the TiN film and the Ti barrier layer between tungsten and the dielectric layer
Data Source
AI summary
A method of manufacturing a tungsten plug is described for producing semiconductor integrated circuits. The method protects the dielectric layer from getting damaged and avoids impact from CMP technology on the electrical RC properties of the semiconductor devices by using a high hardness amorphous carbon layer as an advance pattern film (APF) or barrier layer allowing grinding without altering the dielectric layer, to thereby improve the yield of products.