Gate Insulating Layer Nitrogen Distribution Control
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to enhance the negative bias temperature instability (NBTI) lifetime characteristic of gate insulating layers, particularly in devices below 60-nm scale, where the nitrogen distribution in silicon oxynitride layers affects the electric thickness and reliability of transistors.
Innovation Solution
A method involving sequential nitridation and annealing processes is employed to control the nitrogen distribution within the gate insulating layers, including plasma nitridation and in-situ annealing with varying temperatures and gases, to create regions with varying nitrogen concentrations, thereby optimizing the NBTI performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If nitrogen concentration is increased in the SiON gate insulating layer to reduce electric thickness, then transistor speed is improved, but NBTI lifetime characteristic deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform nitrogen concentration distribution within the gate insulating layer. Specifically, the nitrogen concentration is higher in the upper region (away from substrate) and lower in the lower region (near substrate interface). This spatial variation allows the upper region to provide high-speed performance through reduced electric thickness, while the lower region maintains good NBTI lifetime characteristics by having lower nitrogen concentration at the critical substrate interface.
2Use of energy by moving object
If gate thickness is reduced to achieve low-power operation, then power consumption is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the nitrogen concentration parameter spatially within the gate insulating layer. By controlling nitrogen concentration to be higher in the upper region and lower in the lower region, the effective electric thickness is reduced for low-power operation, while the physical thickness can be maintained at controllable levels. This parameter variation allows simultaneous achievement of low power consumption and manageable manufacturing precision requirements.
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 results in improved NBTI lifetime characteristics by reducing nitrogen concentration at the interface between the insulating layer and the substrate, enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
the first nitridation and the second nitridation are performed by plasma nitridation
Implementation Method 2
a third insulating layer is then formed by sequentially performing a first anneal and a second anneal on the second insulating layer
Data Source
AI summary
A semiconductor device having an improved negative bias temperature instability lifetime characteristic is manufactured by forming a first insulating layer on a substrate, performing a first nitridation on the first insulating layer to form a second insulating layer, and sequentially performing a first and second anneal on the second insulating layer to form a third insulating layer, wherein the second anneal is performed at a higher temperature and with a different gas than the first anneal. A second nitridation is performed on the third insulating layer to form a fourth insulating layer, and a sequential third and fourth anneal on the fourth insulating layer forms a fifth insulating layer. The third anneal is performed at a higher temperature than the first anneal, and the fourth anneal is performed at a higher temperature than the second anneal and with a different gas than the third anneal.