SiON Gate Dielectric Nitridation for Leakage Reduction
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Solution Overview
Problem
Silicon oxide gate dielectric layers in MOS devices face challenges with nitrogen diffusion affecting device reliability and performance due to pinholes and current leakage, especially when trying to form thin layers.
Innovation Solution
A two-step nitridation process is employed to form a SiON layer with a sufficient nitrogen concentration and higher dielectric constant, involving different settings for electric power, duration, and duty cycle in each step, followed by post-annealing with nitrogen and oxygen gas, to prevent nitrogen penetration and enhance electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
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If the gate dielectric layer is made thinner to support miniaturization, then device scaling is achieved, but pinholes form causing direct tunneling current and electrical issues
Solution Approach 1:
The patent creates a composite gate dielectric structure consisting of a silicon oxide layer combined with a nitrogen-containing layer formed through nitridation. This composite structure provides both the thinness required for device scaling and the electrical stability needed to prevent direct tunneling current, as the nitrogen-containing portion fills pinholes and reduces leakage paths
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 resulting SiON layer improves electrical performance and reliability of MOS devices by maintaining a higher nitrogen concentration near the surface while reducing leakage, thus enhancing the overall performance of the semiconductor device.
Implementation Method 1
A nitridation process including at least two steps is performed to nitridate the silicon oxide layer into a SiON layer
Implementation Method 2
The first nitridation step and the second nitridation step each comprise decoupled-plasma nitridation, remote plasma nitridation, or NH3 thermal nitridation
Implementation Method 3
The post-annealing process may include a nitrogen gas annealing step and an oxygen gas annealing step in sequence
Data Source
AI summary
A process for fabricating a semiconductor device is described. A silicon oxide layer is formed. A nitridation process including at least two steps is performed to nitridate the silicon oxide layer into a silicon oxynitride (SiON) layer. The nitridation process comprises a first nitridation step and a second nitridation step in sequence, wherein the first nitridation step and the second nitridation step are different in the setting of at least one parameter.