Silicon Nitride Recess Etching With Bottom Removal Selectivity

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Solution Overview

Problem

Existing methods struggle to selectively etch the bottom portion of a recess region in a semiconductor device's pattern structure without affecting the opening periphery portion, leading to thickness reduction of the surrounding silicon nitride, which impacts device performance.

Innovation Solution

A method involving plasma-enhanced chemical vapor deposition and controlled etching processes is employed to deposit and remove silicon nitride layers, ensuring the bottom portion is etched without affecting the opening periphery portion, using specific gas precursors and etching conditions to maintain the integrity of the top silicon nitride layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an etching process is performed to remove the second silicon nitride on the bottom portion, then the bottom portion is etched, but the top region of the first silicon nitride is also etched causing thickness reduction

Engineering Contradiction:

Improveselective etching precisionVSAvoidthickness maintenance of first silicon nitride

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A third silicon nitride layer is deposited on the first silicon nitride to serve as a protective intermediary layer. This mediator prevents the etching gas from directly contacting and etching the first silicon nitride during the removal of the second silicon nitride, thus maintaining the thickness of the first silicon nitride while enabling selective etching of the bottom portion.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The third silicon nitride layer is deposited in advance before the etching process to protect the first silicon nitride. This preliminary protective action ensures that when the etching process is subsequently performed to remove the second silicon nitride, the first silicon nitride remains unaffected and maintains its designed thickness.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If lithography process is used to selectively etch the second silicon nitride, then selective etching may be achieved, but the process is very difficult to apply because the pattern structure is already formed

Engineering Contradiction:

Improveselective etching capabilityVSAvoidprocess applicability

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The protective third silicon nitride layer is selectively removed only from the opening periphery portion after the etching process. This extraction of the protective layer from specific regions enables subsequent processes to access the first silicon nitride where needed, while maintaining protection in regions where thickness must be preserved.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The third silicon nitride layer provides protective functionality in specific local regions (top surface areas) while allowing other regions (bottom portion through openings) to be etched. This local differentiation of protective function enables selective etching without affecting overall pattern structure integrity.

Inventive Principle:

Principle #3Local quality

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

The method effectively maintains the thickness of the top silicon nitride layer while selectively removing the bottom portion, enhancing the reliability and performance of the semiconductor device.

Implementation Method 1

a deposition step of depositing a second silicon nitride on the first silicon nitride

Methodology Applied

Scientific EffectPlasma-enhanced chemical vapor deposition: Plasma Enhanced Chemical Vapour Deposition

Implementation Method 2

an etching step of etching the second silicon nitride on the opening periphery portion by the thickness deposited in step (a1), etching and removing the second silicon nitride deposited in step (a1) on the bottom portion, and etching the first silicon nitride provided below the second silicon nitride

Methodology Applied

Scientific EffectPlasma etching: Plasma

Data Source

PatentUS12448680B2Method of forming pattern structure including silicon nitride

Publication Date: 2025.10.21 SYSTEM ENGINEERING MEGA SOLUTION CO LTD

AI summary

Disclosed are a method of forming a pattern structure including a silicon nitride. According to the embodiment of the present disclosure, the method of forming a pattern structure includes a step of providing, into a substrate processing apparatus, a substrate having one surface on which a pattern structure including a recess region in which an opening periphery portion and a bottom portion are made of a first silicon nitride is formed, a deposition step of depositing a second silicon nitride on the first silicon nitride, an etching step of etching the second silicon nitride, and a step of performing steps in one cycle n times until the first silicon nitride constituting the bottom portion is removed.