Silicon Recess Etching with Roughness Suppressing Gas

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In semiconductor manufacturing, the formation of silicon layers in recesses on wafers often results in voids and seams due to the roughness of the silicon film surface caused by etching with chlorine gas, leading to uneven etching during anisotropic etching processes.

Innovation Solution

A method involving a semiconductor manufacturing apparatus that supplies a film forming gas to form a silicon film, followed by a process gas containing a halogen gas for etching and a roughness suppressing gas to enhance planarity, using thermal energy to activate the gas and enlarge the recess opening width, and finally depositing silicon onto the etched film to fill the recess.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If chlorine gas is used for etching the silicon film, then the etching speed is improved, but the surface roughness of the silicon film increases

Engineering Contradiction:

Improveetching speedVSAvoidsurface roughness

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the etching gas from pure chlorine gas to a mixed gas containing chlorine gas and hydrogen gas. This parameter change allows the system to maintain high etching speed while reducing surface roughness, as the hydrogen gas component suppresses roughening of the silicon film surface during the etching process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite gas mixture consisting of chlorine gas and hydrogen gas for etching. This composite approach combines the high reactivity of chlorine gas (providing fast etching) with the surface-smoothing effect of hydrogen gas, thereby achieving both high etching speed and low surface roughness simultaneously

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If the recess opening width is small, then the device structure is compact, but voids are formed in the silicon layer during filling

Engineering Contradiction:

Improverecess sizeVSAvoidvoid formation

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent performs preliminary etching of the silicon film on the recess side wall before completing the silicon layer filling. This preliminary action enlarges the recess opening width, creating sufficient space for silicon deposition without forming voids, while the recess remains compact for device integration

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a continuous multi-stage process that combines film formation, etching, and refilling operations. This continuous action ensures that the recess opening is progressively enlarged and then properly filled, preventing void formation while maintaining compact device structure

Inventive Principle:

Principle #20Continuity of useful 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 prevents voids and seams in the silicon layer, ensuring high uniformity and planarity of the silicon film, which in turn allows for consistent and efficient etching without microvoids or seams during anisotropic etching.

Implementation Method 1

forming a silicon film inside a recess formed in a surface of a workpiece by supplying a film forming gas containing silicon to the workpiece

Methodology Applied

Scientific EffectChemical Vapor Deposition: Chemical Vapour Deposition

Implementation Method 2

etching the silicon film formed on a side wall of the recess to enlarge an opening width of the recess by applying thermal energy to the process gas and activating the process gas

Methodology Applied

Scientific EffectThermal activation: Heating

Implementation Method 3

supplying a process gas, which includes a halogen gas for etching the silicon film... etching the silicon film formed on a side wall of the recess

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Implementation Method 4

supplying a process gas, which includes... a roughness suppressing gas for suppressing roughening of a surface of the silicon film after being etched by the halogen gas

Methodology Applied

Scientific EffectGas phase surface treatment:

Implementation Method 5

filling silicon into the recess by supplying the film forming gas to the workpiece and depositing silicon on the silicon film remaining in the recess

Methodology Applied

Scientific EffectChemical Vapor Deposition: Chemical Vapour Deposition

Data Source

PatentUS10529559B2Method of manufacturing semiconductor device, and semiconductor manufacturing apparatus

Publication Date: 2020.01.07 TOKYO ELECTRON LTD

AI summary

There is provided a method of manufacturing a semiconductor device, which includes: forming a silicon film inside a recess formed in a surface of a workpiece by supplying a film forming gas containing silicon to the workpiece; subsequently, supplying a process gas, which includes a halogen gas for etching the silicon film and a roughness suppressing gas for suppressing roughening of a surface of the silicon film after being etched by the halogen gas, to the workpiece; etching the silicon film formed on a side wall of the recess to enlarge an opening width of the recess by applying thermal energy to the process gas and activating the process gas; and subsequently, filling silicon into the recess by supplying the film forming gas to the workpiece and depositing silicon on the silicon film remaining in the recess.