Wet Etching Method for Selective Bevel Film Removal

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Solution Overview

Problem

Existing bevel etching technologies face challenges in selectively removing the upper layer of a substrate with multiple laminated films, particularly when a chemical liquid with a high etching selection ratio between layers is not available, leading to premature loss of the upper layer and exposure of the underlying layer during wet etching.

Innovation Solution

A wet etching method involving the rotation of a substrate with a chemical liquid capable of etching both layers applied to the first surface and an etching inhibiting liquid supplied to the second surface, ensuring the etching inhibiting liquid wraps around the first surface to reach a specific radial position, thereby controlling the etching rate and preventing premature exposure of the underlying layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a chemical liquid with high etching selection ratio is used to selectively remove the upper layer, then the selectivity between layers is improved, but such a chemical liquid does not exist making the process infeasible

Engineering Contradiction:

Improveselectivity of upper layer removalVSAvoidavailability of etching chemical liquid

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent divides the substrate processing into two separate surfaces: the first surface (front) where the upper layer is etched, and the second surface (rear) where etching inhibition is applied. By supplying etching inhibiting liquid to the rear surface that wraps around to the peripheral edge region, the process segments the etching action spatially, achieving selective upper layer removal without requiring a chemical liquid with high selection ratio

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The etching inhibiting liquid acts as an intermediary substance that modifies the etching behavior at the peripheral edge region. By introducing this intermediate agent to the rear surface that wraps around to the edge, the patent creates a controlled environment where the upper layer can be selectively removed while protecting the underlying layer, bypassing the need for highly selective etching chemicals

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If etching is continued until the upper layer is completely removed from the entire peripheral edge portion, then the upper layer removal is complete, but the underlying layer is also lost and base is exposed

Engineering Contradiction:

Improvecompletion of upper layer removalVSAvoidpreservation of underlying layer

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies different treatments to different regions of the substrate: the peripheral edge region receives etching inhibiting liquid from the rear surface that wraps around, while the central region undergoes normal etching. This local differentiation allows complete upper layer removal in the central area while preserving the underlying layer in the peripheral edge region, preventing base exposure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The etching inhibiting liquid is supplied to the rear surface in advance to create a protective effect at the peripheral edge region before the etching process completes. This preliminary anti-action prevents the underlying layer from being exposed by counteracting the etching effect at the edges where the upper layer is thinner

Inventive Principle:

Principle #9Preliminary anti-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 method allows for satisfactory bevel etching of the upper layer on substrates with multiple laminated films, ensuring the upper layer is removed while preserving the underlying layer, thus preventing base exposure and maintaining uniformity.

Implementation Method 1

a process of removing only a peripheral edge portion of a film formed on the surface of a substrate (e.g., a semiconductor wafer) by wet etching

Methodology Applied

Scientific EffectWet etching: Chemical Bonding

Implementation Method 2

the etching inhibiting liquid wraps around the first surface through an edge of the substrate and reaches a first region extending from the edge of the substrate on the peripheral edge portion of the first surface

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS10431448B2Wet etching method, substrate liquid processing apparatus, and storage medium

Publication Date: 2019.10.01 TOKYO ELECTRON LTD

AI summary

A wet etching method according to the present disclosure includes rotating a substrate, supplying an etching chemical liquid to a first surface (a surface on which a device is formed) of the rotating substrate, and supplying an etching inhibiting liquid (DIW) to a second surface (a surface on which no device is formed) of the substrate while supplying the chemical liquid to the substrate. The etching inhibiting liquid wraps around the first surface through an edge of the substrate and reaches a first region extending from the edge of the substrate on the peripheral edge portion of the first surface to a first radial position located radially inward from the edge on the first surface. As a result, bevel etching of an upper layer of a substrate on which a film having two layers is formed may be satisfactorily performed.