CMP Slurry Additives for Silicon Oxide Removal

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Solution Overview

Problem

Conventional chemical mechanical polishing methods face challenges in achieving a suitable balance of polishing properties for dielectric layers, particularly in removing silicon oxide with low defectivity and selective removal rate between silicon nitride and silicon oxide, as the size of semiconductor structures shrinks, making previous acceptable defects yield-limiting.

Innovation Solution

A chemical mechanical polishing composition comprising water, an abrasive, and a substance according to specific formulas, which enhances silicon oxide removal rate and improves polishing defectivity performance by including benzyltrimethylammonium hydroxide or diethylenetriaminepentakis(methylphosphonic acid), along with colloidal silica as the abrasive, to facilitate efficient polishing of silicon oxide and silicon nitride layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional polishing formulations are used, then polishing process is simple, but silicon oxide removal rate is insufficient and defectivity is high

Engineering Contradiction:

Improvesilicon oxide removal rateVSAvoidpolishing defectivity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the chemical composition parameters of the polishing slurry by incorporating specific additives (benzyltrimethylammonium hydroxide and/or diethylenetriaminepentakis(methylphosphonic acid)) alongside colloidal silica abrasive particles. This chemical parameter change enables simultaneous achievement of high silicon oxide removal rate and low defectivity by enhancing the chemical reaction component of the chemical-mechanical polishing process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The polishing composition uses a composite formulation combining colloidal silica abrasive particles with specific chemical additives (benzyltrimethylammonium hydroxide and/or diethylenetriaminepentakis(methylphosphonic acid)). This composite material approach allows the slurry to provide both mechanical abrasion and enhanced chemical reaction, resolving the contradiction between removal rate and defectivity.

Inventive Principle:

Principle #40Composite materials

2Productivity

If polishing pressure is increased to improve removal rate, then silicon oxide removal rate increases, but polishing defects increase

Engineering Contradiction:

Improvesilicon oxide removal rateVSAvoidpolishing defects

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent reduces reliance on mechanical polishing pressure by enhancing the chemical reaction component through specific additives. The benzyltrimethylammonium hydroxide and/or diethylenetriaminepentakis(methylphosphonic acid) promote chemical etching of silicon oxide, allowing lower mechanical pressure to achieve the same or better removal rates with fewer mechanical defects such as scratches and subsurface damage.

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

The composition achieves a significant enhancement in silicon oxide removal rate (≥5-10%) and a substantial reduction in polishing defects (≥50-70%), while maintaining a low nominal polishing pad pressure to minimize damage and defects, thus addressing the need for improved planarization in semiconductor manufacturing.

Implementation Method 1

abrading at least a portion of the substrate to polish the substrate

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 2

The pad is moved (e.g., rotated) relative to the wafer by an external driving force. Simultaneously therewith, a polishing composition ('slurry') or other polishing solution is provided between the wafer and the polishing pad. Thus, the wafer surface is polished and made planar by the chemical and mechanical action of the pad surface and slurry.

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

the substance according to formula I included in the chemical mechanical polishing composition provides an enhanced silicon oxide removal rate and an improved polishing defectivity performance

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Data Source

PatentUS8431490B2Method of chemical mechanical polishing a substrate with polishing composition adapted to enhance silicon oxide removal

Publication Date: 2013.04.30 DUPONT ELECTRONIC MATERIALS HLDG INC

AI summary

A method for chemical mechanical polishing of a substrate is provided, comprising: providing a substrate, wherein the substrate comprises silicon oxide; providing a chemical mechanical polishing composition, comprising, as initial components: water; an abrasive; and a substance according to formula Iwherein R1, R2 and R3 are each independently selected from a C1-4 alky group; providing a chemical mechanical polishing pad with a polishing surface; moving the polishing surface relative to the substrate; dispensing the chemical mechanical polishing composition onto the polishing surface; and, abrading at least a portion of the substrate to polish the substrate; wherein the substance according to formula I included in the chemical mechanical polishing composition provides an enhanced silicon oxide removal rate and an improved polishing defectivity performance; and, wherein at least some of the silicon oxide is removed from the substrate.