HKMG Gate Stack Structure for TiN Oxidation and Resistance Control
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Solution Overview
Problem
The manufacturing process of High-k and Metal Gate (HKMG) transistors, which involves physical vapor deposition (PVD) and atomic layer deposition (ALD), often leads to oxidization of the TiN layer, increasing interlayer resistance and affecting the performance of Dynamic Random Access Memory (DRAM) devices due to diffusion issues between the LaxOy and TiN layers.
Innovation Solution
A method is introduced where a stack layer including an interfacial layer, a high-k dielectric layer, and a work function composite layer is formed, with the work function composite layer prepared by physical vapor deposition to reduce oxidation and facilitate the diffusion of work function adjusting particles, thereby optimizing the transistor structure and reducing interlayer resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical vapor deposition (PVD) and atomic layer deposition (ALD) are used in the manufacturing process, then the transistor structure can be formed, but oxidization of the TiN layer occurs, increasing interlayer resistance
Solution Approach 1:
A work function composite layer is introduced as an intermediary between the high-k dielectric layer and the TiN layer. This composite layer acts as a protective mediator that prevents direct interaction between oxygen and the TiN layer, thereby preventing oxidization while still allowing the necessary diffusion of work function adjusting particles to occur.
Solution Approach 2:
The work function composite layer is formed as a composite structure combining multiple materials with different properties. This composite structure provides both the protective function against oxidization and the functional property of allowing particle diffusion, resolving the contradiction between protection and permeability.
2Reliability
If the work function composite layer is prepared by physical vapor deposition process, then oxidation is reduced and work function adjusting particles can diffuse, but the manufacturing process complexity increases
Solution Approach 1:
The work function composite layer combines multiple functional properties (oxidation resistance and particle diffusion capability) into a single layer structure. This merging of functions reduces the need for multiple separate layers and processes, thereby simplifying the overall manufacturing process while achieving the desired reliability improvements.
3Speed
If work function adjusting particles are gathered at the interface between interfacial layer and high-k dielectric layer, then transistor switching speed is improved, but manufacturing precision requirements increase
Solution Approach 1:
The work function composite layer is prepared in advance with the appropriate properties to facilitate the gathering of work function adjusting particles at the correct interface location. This preliminary preparation of the composite layer creates favorable conditions for particle diffusion and positioning, reducing the precision requirements during subsequent manufacturing steps.
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 approach enhances the performance of semiconductor structures by reducing interlayer resistance, improving the switching speed of transistors, and minimizing metal gate leakage current, thus optimizing the access performance of DRAM devices.
Implementation Method 1
The work function composite layer is prepared by a physical vapor deposition process
Implementation Method 2
Work function adjusting particles are gathered at an interface between the interfacial layer and the high-k dielectric layer
Data Source
AI summary
In a method for manufacturing a semiconductor structure, a substrate is provided; a stack layer is formed on the substrate, the stack layer including an interfacial layer, a high-k dielectric layer and a work function composite layer which are sequentially stacked; a transition layer is formed on the stack layer; and a metal gate layer is formed on the transition layer. The work function composite layer is prepared by a physical vapor deposition process.