Amine-Based CMP Composition for High-Selectivity Polysilicon Polishing
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Solution Overview
Problem
Conventional polysilicon chemical-mechanical polishing (CMP) compositions for integrated circuits and MEMS devices face challenges in achieving high removal rates with high selectivity to silicon oxide and silicon nitride layers while minimizing surface defects and scratches, often requiring hazardous materials and resulting in high defectivity.
Innovation Solution
A CMP composition comprising silica abrasive, an amine-based compound with a carbon to nitrogen ratio of 1:1 to 3:1, and water at a pH of 9 to 12, which effectively polishes substrates by providing high polysilicon removal rates and selectivity while reducing surface defects and scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions use hazardous materials like TMAH to increase polysilicon removal rate, then productivity is improved, but safety and environmental compliance deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters by replacing hazardous materials (TMAH) with alternative compounds (ammonium hydroxide, alkyl ammonium hydroxides, or amine-based compounds) while adjusting pH levels (9-12) and additive concentrations to achieve high polysilicon removal rates without compromising safety or environmental compliance
Solution Approach 2:
The invention uses readily available, non-hazardous chemical compounds (ammonium hydroxide, common amines) that can be easily disposed of or neutralized, replacing expensive and hazardous specialized chemicals like TMAH, making the process both safer and more economically viable
2Productivity
If conventional CMP compositions are used to achieve high polysilicon removal rates, then productivity is improved, but manufacturing precision deteriorates due to high surface defectivity and scratches
Solution Approach 1:
The invention optimizes multiple parameters simultaneously: pH level (9-12), abrasive particle size distribution, concentration of amine-based compounds, and buffer compositions to achieve a balanced state where high removal rates are obtained without generating excessive surface defects or scratches
Solution Approach 2:
The invention introduces buffer compounds and pH control agents as intermediaries that mediate between the abrasive action and the polysilicon surface, controlling the chemical-mechanical interaction to maximize material removal while minimizing surface damage and defect formation
3Productivity
If conventional CMP compositions provide adequate polysilicon removal rates, then productivity is maintained, but safety deteriorates due to requirement of hazardous materials
Solution Approach 1:
The invention changes the chemical safety profile by replacing hazardous materials with safer alternatives (ammonium hydroxide with pH 9-12, common amines) while maintaining or improving removal rates, thereby enhancing process safety and reliability without sacrificing productivity
Solution Approach 2:
The invention converts potentially harmful hazardous chemicals into beneficial safe alternatives, where common household chemicals like ammonium hydroxide and amine-based compounds provide the necessary chemical activity for high-rate polysilicon removal without the safety hazards associated with conventional TMAH-based formulations
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 significant polysilicon removal rates that are 50 to 100 times greater than silicon oxide and silicon nitride rates, with reduced surface defects and scratches, enhancing the planarization process for semiconductor substrates.
Implementation Method 1
CMP utilizes a chemical composition, known as a CMP composition or more simply as a polishing composition (also referred to as a polishing slurry), for selective removal of material from the substrate. Polishing compositions typically are applied to a substrate by contacting the surface of the substrate with a polishing pad (e.g., polishing cloth or polishing disk) saturated with the polishing composition. The polishing of the substrate typically is further aided by the chemical activity of the polishing composition and/or the mechanical activity of an abrasive suspended in the polishing composition or incorporated into the polishing pad
Implementation Method 2
The invention provides a chemical-mechanical polishing composition comprising: (a) silica abrasive; (b) an amine-based compound, wherein the amine-based compound comprises a carbon to nitrogen ratio of about 1:1 to about 3:1; (c) optionally a buffer; and (d) water, wherein the polishing composition has a pH of about 9 to about 12
Implementation Method 3
Chemical-mechanical planarization, or chemical-mechanical polishing (CMP), is a common technique used to planarize substrates. CMP utilizes a chemical composition, known as a CMP composition or more simply as a polishing composition (also referred to as a polishing slurry), for selective removal of material from the substrate
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising: (a) silica abrasive; (b) an amine-based compound, wherein the amine-based compound comprises a carbon to nitrogen ratio of about 1:1 to about 3:1; (c) optionally a buffer; and (d) water, wherein the polishing composition has a pH of about 9 to about 12. The invention also provides a method of chemically-mechanically polishing a substrate, especially a substrate comprising polysilicon, using the inventive polishing composition.