Low-Pressure Oxidation for Uniform Semiconductor Oxide Films
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Solution Overview
Problem
Conventional thermal oxidation methods for semiconductor workpieces, such as silicon wafers, often require high temperatures above 700°C to achieve sufficient oxide growth, leading to insufficient oxidation at lower temperatures and challenges in controlling temperature accuracy, which affects the uniformity and quality of the oxide film.
Innovation Solution
A low-pressure oxidation method and device that generates oxygen radicals by introducing a process gas mixture of hydrogen and oxygen at pressures below 760 Torr, typically 1-20 Torr, and heating to 750-1100°C, allowing for the formation of a high-quality oxide film with improved uniformity and reduced defects by promoting deeper oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermal treatment is used to grow oxide film, then oxidation can be achieved, but temperature must be above 700°C which increases energy consumption and makes temperature control difficult
Solution Approach 1:
The patent changes the fundamental parameter from thermal oxidation to plasma oxidation. By introducing oxygen plasma, the oxidation process can occur at lower temperatures (below 700°C) while maintaining good oxide film quality. The plasma state of oxygen provides highly reactive oxygen species that can oxidize silicon at lower temperatures compared to molecular oxygen in conventional thermal processes.
2Loss of energy
If temperature is reduced below 700°C to save energy, then energy consumption decreases, but oxidation becomes insufficient
Solution Approach 1:
The patent changes the physical state of oxygen from molecular (O2) to atomic/plasma state. This parameter change enables oxidation reactions to proceed at lower temperatures because atomic oxygen and oxygen radicals are much more reactive than molecular oxygen, providing sufficient oxidation even below 700°C.
Solution Approach 2:
The patent uses a composite approach by combining plasma generation technology with oxidation processing. The plasma field (electromagnetic energy) is combined with the chemical oxidation process, creating a plasma-enhanced oxidation system that overcomes the limitation of thermal oxidation at low temperatures.
3Manufacturing precision
If high temperature above 700°C is used to ensure sufficient oxidation, then oxidation completeness improves, but temperature control accuracy becomes difficult which affects oxide film quality
Solution Approach 1:
The patent changes the oxidation mechanism from thermally-driven to plasma-driven. This parameter change shifts the controlling factor from temperature to plasma power and oxygen flow rate, which are easier to control with high precision. Plasma parameters can be controlled independently of substrate temperature, allowing better process control and repeatability.
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 method achieves a high-quality oxide film with enhanced uniformity, reduced defects, and increased oxidation rate, enabling deeper penetration of oxygen radicals into the silicon layer, thus improving the overall film quality and process efficiency.
Implementation Method 1
increasing a temperature within the reaction chamber to cause the process gas to generate oxygen radicals
Implementation Method 2
pumping a reaction chamber such that the reaction chamber has a pressure lower than 760 Torr
Implementation Method 3
exposing the semiconductor workpiece to the oxygen radicals to form an oxide film on a surface of the semiconductor workpiece
Data Source
AI summary
Provided is a low-pressure oxidation treatment method and device for a semiconductor workpiece. The low-pressure oxidation treatment method includes: pumping a reaction chamber such that the reaction chamber has a pressure lower than 760 Torr; introducing a process gas including hydrogen and oxygen to the reaction chamber; increasing a temperature within the reaction chamber to cause the process gas to generate oxygen radicals; and exposing the semiconductor workpiece to the oxygen radicals to form an oxide film on a surface of the semiconductor workpiece.