ISSG Oxynitride Gate Oxide Formation Without Post-Annealing
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Solution Overview
Problem
Existing semiconductor gate structures require post-oxidation annealing and decoupled plasma nitridation to achieve necessary electrical specifications for oxide layers, which increases processing time and complexity, and do not inherently introduce nitrogen into the oxide layer effectively.
Innovation Solution
The in-situ steam generation (ISSG) process forms an oxide layer by reacting a gas mixture of H2, O2, and N2O at high temperatures in a rapid thermal process chamber, allowing for the direct introduction of nitrogen into the oxide layer without the need for post-annealing or separate nitridation processes, and adjusts gas flow rates to optimize electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-oxidation annealing and decoupled plasma nitridation are used to form oxide layers, then electrical specifications are met, but processing time and complexity increase
Solution Approach 1:
The patent combines oxidation and nitridation into a single ISSG process step by introducing nitrogen-containing gases (NH3, N2, or N2O) during the steam generation oxidation process. This merging eliminates the need for separate post-oxidation annealing and decoupled plasma nitridation steps, reducing processing time while maintaining electrical specifications through in-situ nitrogen incorporation into the oxide layer
Solution Approach 2:
The patent performs nitrogen introduction during the oxidation process itself rather than as a subsequent step. By incorporating nitrogen-containing gases into the ISSG process, the oxide layer is formed with the desired nitrogen content and electrical properties in advance, eliminating the need for later annealing and nitridation steps
2Reliability
If post-oxidation annealing and separate nitridation processes are used, then oxide layer specifications are achieved, but process complexity increases
Solution Approach 1:
The patent merges multiple process steps (oxidation, nitrogen introduction, and annealing) into a single integrated ISSG process. By introducing nitrogen-containing gases during steam generation oxidation, the process achieves both oxide formation and nitrogen incorporation in one step, significantly reducing process complexity while meeting oxide layer specifications
Solution Approach 2:
The ISSG process is enhanced to perform multiple functions simultaneously: oxidizing the silicon substrate to form the oxide layer, incorporating nitrogen into the oxide layer to improve electrical properties, and annealing the layer all in one process step. This multi-functionality eliminates the need for separate dedicated process steps
3Productivity
If conventional ISSG is used to form oxide layers, then oxidation is achieved, but nitrogen introduction and electrical properties require additional processes
Solution Approach 1:
The patent combines the high-efficiency ISSG oxidation process with nitrogen introduction by adding nitrogen-containing gases to the steam generation process. This merging maintains the productivity benefits of conventional ISSG while eliminating the need for additional separate processes to introduce nitrogen and improve electrical properties
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 method reduces processing time, improves electrical properties such as gate oxide breakdown and interface trap density, and eliminates the need for post-oxidation annealing, while ensuring the oxide layer meets necessary specifications without additional nitrogen introduction processes.
Implementation Method 1
pre-mixed H2 and O2 are introduced into a rapid thermal process (RTP) chamber. The gas mixture flows across a rotating wafer heated by tungsten-halogen lamps. The hot wafer ignites the reaction between H2 and O2 close to the wafer to form steam
Implementation Method 2
The hot wafer ignites the reaction between H2 and O2 close to the wafer to form steam and thereby oxidize the wafer
Implementation Method 3
Nitrogen may be introduced into the oxide layer to improve performance by reducing boron penetration
Data Source
AI summary
A method of forming an oxide layer in an in-situ steam generation (ISSG) process, including providing a silicon substrate in a rapid thermal process (RTP) chamber and injecting a gas mixture into the RTP chamber. The method further includes heating a surface of the silicon substrate to a reaction temperature, so that the gas mixture reacts close to the surface to form steam and thereby oxidize the silicon substrate to form the oxide layer on the surface, and wherein the gas mixture comprises hydrogen (H2), oxygen (O2) and nitrous oxide (N2O).