Ashable Hardmask PECVD with Wide Electrode Gap at Low Pressure

Solution Overview

Problem

Current methods for forming ashable hard masks (AHMs) using plasma enhanced chemical vapor deposition (PECVD) result in films with high stress, low modulus, and low etch selectivity, limiting their effectiveness as hard masks in semiconductor processing.

Innovation Solution

The method involves exposing a semiconductor substrate to a hydrocarbon precursor gas at low pressure (1 Torr or less) with a wide gap between the showerhead and pedestal in a PECVD process, using a hydrocarbon precursor with a molecular weight of 50 g/mol or less and a C:H ratio of at least 0.5, and acetylene, to deposit an AHM film with low internal stress and high modulus, and patterning the film for etching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If PECVD process is used to form AHM films with high etch selectivity, then etch selectivity is improved, but stress increases and modulus decreases

Engineering Contradiction:

Improveetch selectivityVSAvoidfilm stress

Core Design Contradiction:

Manufacturing precisionVSStress or pressure

Solution Approach 1:

The patent changes key process parameters including using low pressure (1 Torr or less), wide gap electrode spacing (0.70 inches or more), and specific hydrocarbon precursors with controlled molecular weight (≤50 g/mol) and C:H ratio (≥0.5) to achieve high etch selectivity while maintaining low stress and high modulus in AHM films

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite process conditions combining low pressure PECVD with wide gap configuration and specific hydrocarbon precursor gases to create an AHM film with optimized composite properties of high etch selectivity, low stress, and high modulus

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If PECVD process is used to form AHM films with high etch selectivity, then etch selectivity is improved, but modulus decreases

Engineering Contradiction:

Improveetch selectivityVSAvoidfilm modulus

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent changes key process parameters including using low pressure (1 Torr or less), wide gap electrode spacing (0.70 inches or more), and specific hydrocarbon precursors with controlled molecular weight (≤50 g/mol) and C:H ratio (≥0.5) to achieve high etch selectivity while maintaining low stress and high modulus in AHM films

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite process conditions combining low pressure PECVD with wide gap configuration and specific hydrocarbon precursor gases to create an AHM film with optimized composite properties of high etch selectivity, low stress, and high modulus

Inventive Principle:

Principle #40Composite materials

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 produces AHM films with improved etch selectivity and reduced stress, enabling more efficient semiconductor processing by maintaining high modulus and low hydrogen content, thus addressing the limitations of existing AHM films.

Implementation Method 1

depositing on the substrate an AHM film by a plasma enhanced chemical vapor deposition (PECVD) process

Methodology Applied

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

Implementation Method 2

the PECVD process includes igniting a plasma between a showerhead and a pedestal

Methodology Applied

Scientific EffectPlasma: Plasma

Data Source

PatentUS20240030028A1High selectivity, low stress, and low hydrogen carbon hardmasks in low-pressure conditions with wide gap electrode spacing

Publication Date: 2024.01.25 LAM RES CORP

AI summary

Provided herein are methods and related apparatus for depositing an ashable hard mask (AHM) on a substrate by providing a wide gap electrode spacing in low-pressure conditions. A wide gap electrode may facilitate control of parasitic plasmas in low-pressure conditions, thereby enabling formation of high selectivity, low stress, and low-hydrogen AHMs. The AHM may then be used to etch features into underlying layers of the substrate.