Gate Stack Barrier Layer for PMOS Work Function Stability
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Solution Overview
Problem
In PMOS regions of semiconductor devices, the diffusion of N-type metal into P-type work function metal can lead to reduced reliability due to unintended changes in work function.
Innovation Solution
A semiconductor device design that includes a gate stack with a P-type work function pattern, a diffusion prevention pattern of silicon between the P-type and N-type work function patterns, and an N-type work function pattern with a higher aluminum concentration than the P-type work function pattern, preventing aluminum diffusion and maintaining work function stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an N-type metal is used as work function metal in PMOS region, then work function adjustment is achieved, but aluminum diffusion occurs from N-type to P-type work function metal causing reliability reduction
Solution Approach 1:
A diffusion prevention pattern is introduced as an intermediary layer between the P-type work function metal and N-type work function metal. This intermediate layer acts as a barrier that prevents aluminum diffusion from the N-type metal to the P-type metal, thereby maintaining work function stability and improving device reliability without compromising the functionality of either work function metal layer.
Solution Approach 2:
The gate stack is segmented into distinct functional layers with clear boundaries. The diffusion prevention pattern creates a separate barrier layer that isolates the P-type and N-type work function metals, preventing unwanted interaction while maintaining the individual functions of each layer. This segmentation approach allows each material to perform its intended function without compromising the other.
2Reliability
If a diffusion prevention pattern is added to prevent aluminum diffusion, then reliability is improved, but gate stack complexity increases
Solution Approach 1:
The diffusion prevention pattern is formed by adjusting deposition parameters such as thickness control and material composition. By optimizing these parameters, the pattern achieves effective diffusion prevention while maintaining a relatively simple structure that integrates seamlessly with the existing gate stack architecture, minimizing the increase in device complexity.
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 enhances the reliability of semiconductor devices by preventing aluminum diffusion between work function layers, thus maintaining consistent work function and improving device performance.
Implementation Method 1
preventing aluminum diffusion and maintaining work function stability
Data Source
AI summary
Provided a semiconductor device. The semiconductor device comprises an active pattern extending in a first direction on a substrate, a gate stack extending in a second direction intersecting the first direction on the active pattern, and a source/drain pattern on at least one side of the gate stack, wherein the gate stack includes a first work function pattern, a second work function pattern on the first work function pattern, and a diffusion prevention pattern between the first work function pattern and the second work function pattern, and wherein a concentration of aluminum in the second work function pattern is greater than a concentration of aluminum in the first work function pattern.