Bilayer Seal Material for Seamless Semiconductor Air Gaps

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Solution Overview

Problem

The semiconductor industry faces challenges in forming seamless seal layers to prevent damage to air gaps in semiconductor devices, as existing fabrication processes often result in seams that can lead to defects and low device yield due to etching and chemical solutions penetrating the seal material, causing collapse or trapping of chemicals within the air gaps.

Innovation Solution

A bilayer seal material is formed by depositing a first silicon oxycarbide seal material on opposing sidewalls and a second seal material on the first material, followed by a treatment process, such as an anneal in an oxygen ambient environment, to remove seams and ensure a seamless enclosure of air gaps between terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-layer seal material is used to enclose air gaps, then the fabrication process is simple, but seams form in the seal material allowing etching and chemical solutions to penetrate, causing damage to air gaps

Engineering Contradiction:

Improveseal material deposition processVSAvoidair gap protection

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The seal material is divided into multiple layers (first seal material layer and second seal material layer) with different materials and functions. The first layer provides initial sealing and protection, while the second layer enhances seam-free enclosure and chemical resistance, collectively preventing etching and chemical solution penetration that would damage air gaps.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite seal material structure combining different dielectric materials (e.g., silicon nitride, silicon oxycarbide, silicon oxide) in layers. Each material is selected for specific properties such as etch resistance, chemical stability, and sealing effectiveness, creating a composite structure that superiorly protects air gaps compared to single-material seals.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If seams are present in the seal material, then the fabrication process is easier, but etching and chemical solutions penetrate through seams causing collapse or chemical trapping in air gaps

Engineering Contradiction:

Improveseal material formationVSAvoidetching and chemical solution penetration

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The first seal material layer is deposited and treated (e.g., annealed) before the second seal material layer is added. This preliminary formation and treatment of the first layer creates a foundation that reduces seam formation, and the subsequent second layer further seals any remaining imperfections, preventing etching and chemical solution penetration in advance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs thermal treatment (annealing) at specific temperatures (e.g., 400-600°C) to modify the physical and chemical parameters of the seal materials. This thermal processing reduces internal stress, improves material density, and minimizes seam formation, thereby preventing penetration by etching and chemical solutions.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a bilayer seal material with treatment process is used, then seam-related defects are reduced and yield improves, but the fabrication process complexity increases

Engineering Contradiction:

Improvedevice yieldVSAvoidfabrication process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bilayer seal structure serves multiple functions: the first layer provides initial sealing and stress management, the second layer enhances chemical and etch resistance, and the thermal treatment process simultaneously reduces seams and improves material properties. This multi-functionality achieves high reliability and device yield while keeping the added process complexity manageable.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively reduces damage to air gaps, enhances device performance by lowering the effective dielectric constant, and improves yield by preventing defects associated with seam-related issues in semiconductor devices.

Implementation Method 1

depositing a first seal material on opposing sidewalls and a second seal material on the first material

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

followed by a treatment process, such as an anneal in an oxygen ambient environment, to remove seams

Methodology Applied

Scientific EffectAnnealing: Annealing

Data Source

PatentUS11901220B2Bilayer seal material for air gaps in semiconductor devices

Publication Date: 2024.02.13 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure relates to a method for forming a semiconductor device includes forming an opening between first and second sidewalls of respective first and second terminals. The first and second sidewalls oppose each other. The method further includes depositing a first dielectric material at a first deposition rate on top portions of the opening and depositing a second dielectric material at a second deposition rate on the first dielectric material and on the first and second sidewalls. The second dielectric material and the first and second sidewalls entrap a pocket of air. The method also includes performing a treatment process on the second dielectric material.