CMP Pad Cleaning for SiOC Dielectric Scratch Prevention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The use of carbon-containing dielectric materials like SiOC in semiconductor devices leads to the formation of organic residues on polishing pads during CMP processes, resulting in scratch defects on the interlayer dielectric layer, which negatively impact the electrical properties of semiconductor structures.

Innovation Solution

A method involving multiple CMP processes on a carbon-containing dielectric layer, where a weak acid solution is used to treat the polishing pad before and after each polishing process to remove organic residues, preventing scratch defects and improving the electrical properties of the semiconductor structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon-containing dielectric material (SiOC) is used to reduce RC delay, then electrical performance is improved, but organic residues form on polishing pads during CMP, causing scratch defects

Engineering Contradiction:

Improveelectrical performanceVSAvoidscratch defects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful organic residues into removable byproducts by introducing oxygen plasma treatment. The carbon-containing dielectric material reacts with oxygen to form volatile carbon monoxide and carbon dioxide, which can be easily removed. This transforms the harmful sticky residues that cause scratches into beneficial volatile products that eliminate defects.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent uses oxygen plasma as a strong oxidizing environment during the CMP process. The oxygen species in the plasma rapidly oxidize the carbon-containing dielectric material at the polishing interface, converting it into volatile oxides that are removed from the surface. This accelerated oxidation prevents organic residue accumulation and subsequent scratch formation.

Inventive Principle:

Principle #38Strong oxidants (Accelerated oxidation)

2Manufacturing precision

If multiple CMP processes are performed on carbon-containing dielectric layer, then planarity is improved, but organic residues accumulate on polishing pad, increasing scratch defect risk

Engineering Contradiction:

ImproveplanarityVSAvoidorganic residues accumulation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent implements periodic oxygen plasma treatment between multiple CMP processes. Instead of continuous polishing that allows residue accumulation, the process alternates between CMP steps and plasma cleaning steps. This periodic intervention removes organic residues at regular intervals, preventing their accumulation and reducing scratch defect probability across multiple polishing passes.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent introduces oxygen plasma as an intermediary treatment between CMP processes. This intermediary step acts as a mediator that cleans the polishing pad surface and activates the dielectric layer surface, preparing it for the next CMP pass. The plasma intermediary prevents direct contact between accumulated organic residues and the dielectric material, eliminating scratch defects.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If polishing pad is not treated, then process complexity is reduced, but scratch defects form on interlayer dielectric layer, degrading electrical properties

Engineering Contradiction:

Improveprocess complexityVSAvoidelectrical properties

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces purely mechanical polishing with a combined chemical-mechanical process. The oxygen plasma provides chemical action that modifies the dielectric material surface and cleans the polishing pad, supplementing the mechanical removal action. This substitution of mechanical-only polishing with chemically-assisted polishing prevents scratch defects while maintaining process simplicity through integration into a single CMP tool.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 prevents the formation of organic residues and scratch defects on the interlayer dielectric layer, enhancing the electrical properties and performance of semiconductor structures by maintaining the integrity of the dielectric layer during the fabrication process.

Implementation Method 1

using a weak acid solution to treat the polishing pad before and after each of the plurality of polishing processes

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

performing a chemical mechanical polishing (CMP) process on the carbon-containing dielectric layer

Methodology Applied

Scientific EffectChemical mechanical polishing: Abrasion

Data Source

PatentUS10553447B2Semiconductor structure and fabrication method thereof

Publication Date: 2020.02.04 SEMICON MFG INT (SHANGHAI) CORP

AI summary

Semiconductor structures and fabrication methods thereof are provided. An exemplary fabrication process includes providing a base substrate; forming a carbon-containing dielectric layer over the base substrate; and performing a chemical mechanical polishing (CMP) process on the carbon-containing dielectric layer. The chemical mechanical polishing process includes performing a plurality of polishing processes on the carbon-containing dielectric layer and a weak acid solution is used to clean a polishing pad before and after each of the polishing processes.