Aluminum Alloy Gate Structure for Semiconductor Reliability
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Solution Overview
Problem
The use of aluminum gates in semiconductor devices is prone to corrosion during chemical mechanical polishing, leading to defects and reduced reliability due to its reactive nature with high-k materials, resulting in leakage current issues and performance degradation.
Innovation Solution
Employing an aluminum alloy, specifically an AlTi alloy, as the metal gate material, which is more resistant to corrosion and mechanical damage, and incorporating a stack of TiN and TaN barrier layers along with a TiAl alloy work function layer to enhance durability and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum is used as gate material, then good electrical properties and low cost are achieved, but corrosion resistance during CMP and cleaning processes deteriorates
Solution Approach 1:
The patent applies composite materials by forming a multi-layer gate structure consisting of a first barrier layer (TiN), a metal gate layer (aluminum alloy), and a second barrier layer (TaN). This composite structure combines the low work function and good electrical properties of aluminum with the corrosion resistance and barrier properties of TiN and TaN layers, resolving the contradiction between electrical performance and corrosion resistance
Solution Approach 2:
The patent uses intermediary barrier layers (TiN and TaN) that mediate between the aluminum gate material and the external environment. These intermediary layers protect the aluminum from direct exposure to corrosive chemicals during CMP and cleaning processes while allowing the aluminum to maintain its electrical function, thus resolving the contradiction between corrosion resistance and structural simplicity
2Ease of manufacture
If aluminum gate is used, then manufacturing simplicity is maintained, but defects and pits occur during CMP processes
Solution Approach 1:
The patent applies composite materials by forming a multi-layer gate structure consisting of a first barrier layer (TiN), a metal gate layer (aluminum alloy), and a second barrier layer (TaN). This composite structure combines the low work function and good electrical properties of aluminum with the corrosion resistance and barrier properties of TiN and TaN layers, resolving the contradiction between electrical performance and corrosion resistance
Solution Approach 2:
The patent uses intermediary barrier layers (TiN and TaN) that mediate between the aluminum gate material and the external environment. These intermediary layers protect the aluminum from direct exposure to corrosive chemicals during CMP and cleaning processes while allowing the aluminum to maintain its electrical function, thus resolving the contradiction between corrosion resistance and structural simplicity
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 use of AlTi alloy reduces defects and corrosion in the metal gate, thereby improving the reliability and performance of semiconductor devices by maintaining electrical properties and withstanding CMP processes effectively.
Implementation Method 1
performing annealing to melt the upper portion of the first metal layer and the lower portion of the second metal layer into an alloy
Data Source
AI summary
A semiconductor device and a method for manufacturing the semiconductor device are provided. The semiconductor device uses an aluminum alloy, rather than aluminum, for a metal gate. Therefore, the surface of the high-k metal gate after the CMP is aluminum alloy rather than pure aluminum, which can greatly reduce defects, such as corrosion, pits and damage, in the metal gate and improve reliability of the semiconductor device.