Plasma Oxidation of Concave Silicon Structures

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Solution Overview

Problem

The existing methods for forming a sacrificial oxide film on the inner surface of a concave structure in semiconductor devices, particularly those with high aspect ratios, face challenges in achieving uniform thickness due to microloading effects and plane orientation dependencies, leading to suboptimal electrical characteristics.

Innovation Solution

A substrate processing apparatus is employed that includes a plasma generation space where an oxygen-containing gas is plasma-excited, with a coil set to resonate at an integral multiple of the high frequency power wavelength, allowing for uniform oxidation of the inner surface of the concave structure, forming a sacrificial oxide film with improved thickness uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If thermal oxidation is used to form a sacrificial oxide film on the inner surface of a concave structure with high aspect ratio, then the oxidation process can be performed, but the thickness uniformity of the sacrificial oxide film cannot be obtained due to microloading effect and plane orientation dependency

Engineering Contradiction:

Improvethickness uniformity of sacrificial oxide filmVSAvoidmicroloading effect and plane orientation dependency

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the oxidation method from thermal oxidation to plasma oxidation, altering the physical and chemical parameters of the oxidation process. Plasma oxidation operates at lower temperatures and uses reactive species in the plasma state, which fundamentally changes how oxidation occurs on the substrate surface, eliminating the microloading effect and orientation dependency that plague thermal oxidation processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal field-based oxidation mechanism with a plasma field-based mechanism. Instead of relying on thermal diffusion and chemical reactions driven by heat, the invention uses plasma-generated reactive species (such as oxygen radicals and ions) to achieve oxidation, substituting a thermal-mechanical process with a plasma-chemical process that provides uniform reaction conditions across different surface orientations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If a coil with electrical length set to integral multiple of wavelength is used for plasma generation, then uniform plasma distribution is achieved, but the device complexity increases

Engineering Contradiction:

Improveuniformity of sacrificial oxide film thicknessVSAvoidcoil configuration complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent employs periodic electromagnetic action by setting the coil's electrical length to an integral multiple of the radio frequency wavelength. This creates standing wave patterns with periodic nodes and antinodes that distribute plasma generation uniformly throughout the reaction chamber. The periodic electromagnetic field ensures consistent plasma density and oxidation rate across the substrate surface, including vertical sidewalls of concave structures.

Inventive Principle:

Principle #19Periodic action

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 enables the formation of a sacrificial oxide film with enhanced thickness uniformity, which is crucial for maintaining desired electrical characteristics of semiconductor devices, particularly by preventing plasma sheath formation and ensuring uniform active species supply, even on surfaces with different crystal orientations.

Implementation Method 1

a plasma generation space where an oxygen-containing gas supplied thereto is plasma-excited

Methodology Applied

Scientific EffectPlasma excitation: Plasma

Implementation Method 2

oxidizing, by the plasma, a surface of the silicon film exposed in the concave structure

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

a coil provided at an outer peripheral portion of the plasma generation space wherein an electrical length of the coil is set to an integral multiple of a wavelength of a high frequency power applied thereto

Methodology Applied

Scientific EffectElectromagnetic resonance: Resonance

Data Source

PatentUS11189483B2Method of manufacturing semiconductor device and non-transitory computer-readable recording medium

Publication Date: 2021.11.30 KOKUSAI DENKI KK

AI summary

According to one aspect of the technique of the present disclosure, there is provided a method of manufacturing a semiconductor device including: (a) providing a semiconductor processing apparatus including a substrate process chamber, a coil and a substrate support; (b) placing a target substrate with a concave structure of a silicon film on a substrate support, wherein a deteriorated layer is formed on an inner surface of the concave structure by deterioration of a surface layer of the silicon film due to an etching process; (c) supplying an oxygen-containing gas into the substrate process chamber; (d) applying a high frequency power to the coil to generate plasma of the oxygen-containing gas; and (e) oxidizing, by the plasma, a surface of the silicon film exposed in the concave structure wherein the deteriorated layer is formed on the surface.