Low-K Dielectric Etch Damage Reduction via Fluorocarbon Curing

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Solution Overview

Problem

Low-k dielectric materials in semiconductor processing are often damaged during etch and strip processes, leading to changes in material composition, morphology, and surface properties, which can result in device yield loss and reliability failures, and existing methods have only achieved limited success in reducing this damage.

Innovation Solution

A method involving the deposition of a fluorocarbon layer on the low-k dielectric layer, followed by curing and subsequent stripping, which reduces damage by making the surface more resistant to plasma and chemical attacks during the strip process, allowing for effective prevention of low-k damage in dual damascene processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional plasma etching and strip processes are used on low-k dielectric layers, then the etching and stripping functions are achieved, but the low-k dielectric material suffers damage including changes in composition, morphology, and surface properties

Engineering Contradiction:

Improvelow-k dielectric integrityVSAvoidplasma and chemical damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A fluorocarbon protective layer is deposited on the low-k dielectric layer before the strip process. This intermediary layer acts as a barrier between the aggressive strip plasma and the low-k dielectric material, preventing direct damage while allowing the strip process to proceed effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The fluorocarbon protective layer is deposited and cured before the strip process begins. This preliminary action prepares the low-k dielectric surface in advance to resist the harmful effects of the subsequent strip plasma, preventing damage before it occurs.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a fluorocarbon protective layer is deposited and cured before stripping, then damage to the low-k dielectric is significantly reduced, but the process time and complexity increase

Engineering Contradiction:

Improvelow-k dielectric integrityVSAvoidprocess steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The deposition of the fluorocarbon protective layer, its curing, and the subsequent strip process are all performed in a single plasma reactor chamber without breaking vacuum. This merging of multiple process steps into one continuous operation reduces overall process complexity and eliminates the need for separate repair tools.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The plasma reactor chamber is used for multiple functions: depositing the fluorocarbon layer, curing it, and performing the strip process. This multi-functionality eliminates the need for separate specialized equipment for each step, reducing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a fluorocarbon protective layer is deposited and cured before stripping, then damage to the low-k dielectric is significantly reduced, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvelow-k dielectric integrityVSAvoidprocess integration

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

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 significantly reduces low-k damage, as demonstrated by reduced material loss after HF dipping, and allows for nearly damage-free results under optimal conditions, with the added benefit of maintaining critical dimension accuracy and reducing production costs by eliminating the need for separate repair tools.

Implementation Method 1

providing energy from the at least one electrode to form the fluorocarbon deposition gas into a deposition plasma, which deposits a fluorocarbon layer on the low-k dielectric layer

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

providing energy from the at least one electrode to form the etch gas into a plasma, which etches features into the low-k dielectric layer

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 3

providing energy from the at least one electrode to form the stripping gas into a plasma, which strips the photoresist mask

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 4

The fluorocarbon layer is cured in the plasma processing chamber

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS8236188B2Method for low-K dielectric etch with reduced damage

Publication Date: 2012.08.07 LAM RES CORP

AI summary

A method for etching features in a low-k dielectric layer disposed below an organic mask is provided by an embodiment of the invention. Features are etched into the low-k dielectric layer through the organic mask. A fluorocarbon layer is deposited on the low-k dielectric layer. The fluorocarbon layer is cured. The organic mask is stripped.