Semiconductor Hole Etching Uniformity Control

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Solution Overview

Problem

Manufacturing semiconductor devices with uniformly high aspect ratio holes is challenging due to variations in etching rates and the formation of non-uniform hole diameters, which affects device characteristics and yield.

Innovation Solution

A method involving the formation of a workpiece with alternating layers, followed by the deposition of specific films on the surface and side walls, where a first etchant with a higher etching rate is used to selectively remove these films from the upper surface while a second etchant with a higher etching rate for the workpiece material enlarges the hole diameter, maintaining uniformity and aspect ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If conventional etching methods are used to form high aspect ratio holes, then the holes can be formed deep enough, but the hole diameter becomes non-uniform and aspect ratio uniformity deteriorates

Engineering Contradiction:

Improvehole depthVSAvoidhole diameter uniformity

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The etching process is divided into multiple sequential steps with different etchants, each targeting specific layers at different rates. The first etchant removes the first film and second film at different rates, while the second etchant selectively removes the third film and fourth film, creating a segmented approach that maintains hole uniformity throughout the deep etching process

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different etchants with specific selective etching characteristics are applied to different regions and layers of the stacked film structure. Each etchant is chosen to have high selectivity for specific materials, allowing precise control of etching at different depths and locations within the hole formation process

Inventive Principle:

Principle #3Local quality

2Reliability

If multiple films are formed on the workpiece surface and side walls, then side wall protection is improved, but the process complexity increases

Engineering Contradiction:

Improveside wall protectionVSAvoidfilm deposition process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The first film and second film are deposited on the workpiece surface and side walls before the etching process begins, providing preliminary protection to the side walls. This preliminary action ensures that side wall integrity is maintained throughout the subsequent deep etching operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The stacked film structure acts as an intermediary layer between the etchant and the workpiece side walls. These films are strategically designed with different etching rates to mediate the etching process, protecting the side walls while allowing controlled removal of specific layers

Inventive Principle:

Principle #24Intermediary (Mediator)

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 semiconductor devices with uniformly high aspect ratio holes, reducing device characteristic fluctuations and improving manufacturing yield by controlling the etching process and minimizing dust generation.

Implementation Method 1

selectively removing the first film and the second film from the upper surface of the workpiece using a first etchant so that at least a part of the first film formed on the upper portion and at least a part of the second film formed on the surface of the first film remain; wherein an etching rate of the first film by the first etchant is higher than an etching rate of the second film by the first etchant

Methodology Applied

Scientific EffectSelective etching:

Implementation Method 2

removing at least a part of a portion of the workpiece which is exposed through the hole using a second etchant

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS10026622B2Method for manufacturing semiconductor device

Publication Date: 2018.07.17 KIOXIA CORP

AI summary

According to one embodiment, a method for manufacturing a semiconductor device includes forming a hole extending in a first direction in a workpiece. The method includes forming a first film on an upper surface of the workpiece and an upper portion of a side wall of the hole. The method includes forming a second film on the first film. The method includes removing portions of the first and second films from the upper surface of the workpiece so that at least a part of the first and second films formed on the upper portion remain. The method includes removing at least a part of a portion of the workpiece which is exposed through the hole using a second etchant. An etching rate of the first etchant for the first film is higher than an etching rate of the first etchant for the second film.