Gate Stack Cap Layer Diffusion for Threshold Voltage Control
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Solution Overview
Problem
The semiconductor industry faces challenges in manufacturing low-cost, high-performance, and low-power integrated circuits due to increased complexity from scaling down semiconductor IC dimensions, which affects the control of threshold voltage in transistors.
Innovation Solution
A method of forming a gate stack in semiconductor devices involves treating intermediate structures with silicon-containing or aluminum-containing gases in a non-plasma ambient at elevated temperatures to diffuse silicon or aluminum atoms into cap layers, preventing oxidation and controlling threshold voltage, thereby improving the electrical performance of transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon or aluminum atoms are diffused into cap layers using non-plasma gas treatment at elevated temperatures, then oxidation is prevented and threshold voltage control is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies parameter changes by treating the cap layer with silicon-containing or aluminum-containing gases at elevated temperatures (typically 200-450°C) in a non-plasma ambient. This thermal treatment diffuses silicon or aluminum atoms into the cap layer, modifying its compositional parameters to prevent oxidation and control threshold voltage without requiring plasma processing
Solution Approach 2:
The patent uses silicon-containing gases (such as silane) or aluminum-containing gases as intermediary substances to deliver silicon or aluminum atoms to the cap layer. These gas-phase intermediaries enable atomic diffusion into the cap layer structure, achieving oxidation prevention and threshold voltage control through a non-plasma intermediary process
2Productivity
If scaling down semiconductor IC dimensions is continued to improve production efficiency and lower costs, then production efficiency increases and costs decrease, but process complexity increases
Solution Approach 1:
The patent replaces plasma-based processing (a complex mechanical/physical system requiring vacuum chambers, RF power sources, and plasma generation equipment) with a non-plasma gas treatment process. This substitution uses simpler thermal diffusion in a non-plasma ambient, reducing equipment complexity and process steps while maintaining effectiveness at scaled dimensions
Solution Approach 2:
The patent extracts the essential function of plasma treatment (atom diffusion into the cap layer) and separates it from the complex plasma generation mechanism. By using non-plasma gas treatment, the invention removes the need for plasma-related equipment and process controls, retaining only the essential atomic diffusion function at scaled dimensions
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 control of threshold voltage and prevents unwanted increases, leading to improved electrical performance and reduced complexity in transistor manufacturing.
Implementation Method 1
treating intermediate structures with silicon-containing or aluminum-containing gases in a non-plasma ambient at elevated temperatures to diffuse silicon or aluminum atoms into cap layers
Implementation Method 2
preventing oxidation and controlling threshold voltage
Data Source
AI summary
A semiconductor device includes a substrate, a semiconductor fin extending from the substrate, a gate dielectric layer over the semiconductor fin, a metal nitride layer comprising a first portion over the gate dielectric layer and a second portion over the first portion, and a fill layer over the metal nitride layer. The second portion has an aluminum concentration greater than an aluminum concentration of the first portion.