Boron Film Mask for Semiconductor Etching Selectivity

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Solution Overview

Problem

The challenge in manufacturing highly integrated semiconductor devices lies in ensuring the selectivity of etching for insulating films while maintaining efficient processing, as existing methods face difficulties with mask thickness, metallic contamination, and etching inhibition.

Innovation Solution

A method involving the formation of a stacked film with alternating insulating and conductive layers, using a silicon oxide mask for etching, and employing specific etching gases like chlorine and tetrafluoromethane, along with controlled ion energy, to achieve high aspect ratio hole patterns and reduce manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the thickness of the silicon oxide mask is increased to ensure etching selectivity for insulating films, then etching selectivity is improved, but mask processing difficulty increases and processing time becomes longer

Engineering Contradiction:

Improveetching selectivityVSAvoidmask processing difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter of the mask from silicon oxide to boron film, which fundamentally alters the etching selectivity characteristics. The boron film provides sufficient selectivity for etching insulating films without requiring increased thickness, thereby avoiding the processing difficulties associated with thick masks while maintaining the desired etching performance

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a metal mask is used to improve etching selectivity, then etching performance is improved, but etching inhibition by reaction products and metallic contamination occur

Engineering Contradiction:

Improveetching selectivityVSAvoidmetallic contamination

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent employs a boron film mask that can be easily removed after serving its purpose as an etching mask. The boron film is deposited as a thin layer specifically for the etching process and then removed, avoiding the persistent contamination issues associated with metal masks. This disposable approach eliminates metallic contamination while maintaining etching selectivity

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 suppresses sediment generation, prevents tapered hole formation, reduces manufacturing costs, and allows for collective etching of both conductive and insulating films, enhancing etching selectivity and yield while minimizing mask thickness.

Implementation Method 1

etching the film containing boron with a gas containing chlorine

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Implementation Method 2

using the patterned film containing silicon oxide as a mask

Methodology Applied

Scientific EffectMasking effect:

Data Source

PatentUS8642484B2Method for manufacturing semiconductor device

Publication Date: 2014.02.04 KIOXIA CORP

AI summary

According to one embodiment, a method for manufacturing a semiconductor device includes forming a film containing boron on a semiconductor substrate, forming a film containing silicon oxide on the film containing boron, patterning the film containing silicon oxide and etching the film containing boron with a gas containing chlorine by using the patterned film containing silicon oxide as a mask.