Semiconductor Gate Electrode Diffusion Barrier for Threshold Voltage Control
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Solution Overview
Problem
Conventional semiconductor devices with combined N-type and P-type field effect transistors face issues of nonuniform gate electrode composition due to mutual diffusion of gate electrode materials during heating, leading to deviations in threshold voltage control.
Innovation Solution
A semiconductor device with a diffusion barrier region made of a material different from the gate electrode sections, preventing contact between N-type and P-type gate electrodes, ensuring uniform composition and controlled threshold voltage by maintaining lower diffusion coefficients within the barrier region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gate electrodes for NMOS and PMOS transistors are simultaneously formed by heating, then manufacturing process is simplified, but gate electrode composition becomes nonuniform due to mutual diffusion
Solution Approach 1:
The gate electrode line is segmented into distinct sections for NMOS and PMOS transistors, with each section capable of having different material compositions. This segmentation allows independent optimization of gate electrode properties for each transistor type while preventing mutual diffusion through material boundaries or interface layers.
Solution Approach 2:
Different sections of the gate electrode line are assigned different material compositions tailored to the specific requirements of NMOS and PMOS transistors. The NMOS gate electrode section has one composition optimized for n-type semiconductor properties, while the PMOS gate electrode section has a different composition optimized for p-type semiconductor properties, achieving local quality optimization.
2Manufacturing precision
If different silicide materials are used for NMOS and PMOS gate electrodes, then threshold voltage control is improved, but manufacturing complexity increases due to multiple deposition and siliciding steps
Solution Approach 1:
A single gate electrode line structure serves multiple functions: it provides the gate electrode for both NMOS and PMOS transistors, enables different material compositions in different sections, and maintains electrical connectivity while allowing independent threshold voltage control. This multi-functionality reduces the need for separate gate electrode structures.
Solution Approach 2:
The gate electrode line is designed with dynamic material distribution, where the composition can vary along the length of the line to accommodate different transistor requirements. This dynamic approach allows the same physical structure to adapt to different functional requirements through material composition variations.
3Productivity
If gate electrode materials with larger diffusion coefficients are used, then siliciding reaction rate is improved, but infiltration into other gate electrode areas increases causing nonuniform composition
Solution Approach 1:
An intermediary layer or interface structure is introduced between the NMOS and PMOS gate electrode sections to prevent mutual diffusion of metal atoms during siliciding. This intermediary acts as a diffusion barrier that allows the siliciding reaction to proceed at high rates within each section while preventing cross-contamination between sections.
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 effectively prevents mutual diffusion of gate electrode materials, achieving uniform gate electrode composition and precise control of threshold voltage, thereby enhancing the operational properties of the semiconductor device.
Implementation Method 1
preventing mutual diffusion of gate electrode materials, achieving uniform gate electrode composition
Implementation Method 2
A semiconductor device with a diffusion barrier region made of a material different from the gate electrode sections, preventing contact between N-type and P-type gate electrodes, ensuring uniform composition and controlled threshold voltage by maintaining lower diffusion coefficients within the barrier region
Data Source
AI summary
In a semiconductor device, a gate electrode having a uniform composition prevents deviation in a work function. Controlling a Vth provides excellent operation properties. The semiconductor device includes an NMOS transistor and a PMOS transistor with a common line electrode. The line electrode includes electrode sections (A) and (B) and a diffusion barrier region formed over an isolation region so that (A) and (B) are kept out of contact. The diffusion barrier region meets at least one of: (1) The diffusion coefficient in the above diffusion barrier region of the constituent element of the above electrode section (A) is lower than the interdiffusion coefficient of the constituent element between electrode section (A) materials; and (2) The diffusion coefficient in the above diffusion barrier region of the constituent element of the above electrode section (B) is lower than the interdiffusion coefficient of the constituent element between electrode section (B) materials.