Semiconductor Device Oxide Formation with Barrier-Layer Thickness Control
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Solution Overview
Problem
The existing in-situ steam generation process for forming oxide in semiconductor structures results in a thick oxide layer with high breakdown voltage and large defect state density, making it difficult to achieve the desired thickness of 3 nm or less for optimal electrical performance.
Innovation Solution
A method involving the deposition of a barrier layer on a substrate to control the growth rate of an initial oxide, followed by its partial removal to form a device oxide with a thickness of 1 nm to 3 nm, using a combination of chemical vapor deposition and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ISSG process is used to form oxide on the substrate, then the oxide is dense and has good insulating properties, but the oxide thickness is large and difficult to control for achieving desired electrical performance
Solution Approach 1:
A thin film layer (such as a nitride layer or oxide-nitride-oxide structure) is formed on the substrate before the oxidation process. This preliminary layer acts as a barrier to oxygen diffusion, controlling the oxide growth rate and enabling precise thickness control of the final device oxide, while still allowing the oxide to achieve dense structure and good insulating properties through the oxidation process
2Productivity
If high temperature oxidation is used to form oxide, then the oxide formation speed is high, but the oxide thickness becomes too large to meet the requirements for thin oxide structures
Solution Approach 1:
The formation of a thin film barrier layer changes the oxidation kinetics by limiting oxygen diffusion to the substrate. This allows the oxidation process to proceed at high temperatures with controlled oxide growth rate, producing thin oxides (1-3 nm) with the desired dense structure and insulating properties, rather than thick oxides that would form without the barrier layer
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 allows for precise control of the oxide thickness, improving electrical performance by reducing the thickness of the device oxide and enhancing breakdown voltage while minimizing defect state density.
Implementation Method 1
depositing a barrier layer on the substrate, the barrier layer at least covering the device region; forming an initial oxide which is located in the device region and in contact with the barrier layer
Implementation Method 2
removing part of the initial oxide to form a device oxide
Implementation Method 3
Oxygen doped with a small amount of hydrogen is used as a reaction gas. At a high temperature, the hydrogen and the oxygen undergo a chemical reaction similar to combustion, generating a large amount of gas-phase active free radicals. The gas-phase active free radicals oxidize the substrate to form oxides.
Data Source
AI summary
A method for preparing a semiconductor structure includes: providing a substrate which includes a device region and a shallow trench isolation region surrounding the device region, in which the device region is exposed from a surface of the substrate; depositing a barrier layer on the substrate, the barrier layer at least covering the device region; forming an initial oxide which is located in the device region and in contact with the barrier layer; and removing part of the initial oxide to form a device oxide.