Silicon Nitride Polishing Composition Selectivity Control
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Solution Overview
Problem
The CMP process for polishing silicon nitride layers is inefficient due to their high mechanical strength, leading to low polishing speeds and prolonged processing times, and conventional compositions struggle to control selectivity between different layers effectively.
Innovation Solution
A composition comprising colloidal silica, a phosphoric acid compound, a sulfuric acid compound, and an oxidizing agent is used to improve polishing speed and control selectivity, where the oxidizing agent's content and pH of the composition allow for precise control of polishing ratios between metal, oxide insulating, and silicon nitride layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional CMP composition is used to polish silicon nitride layer, then polishing process can be carried out, but polishing speed is low due to high mechanical strength of silicon nitride
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by introducing oxidizing agents (potassium permanganate, sodium chlorite, calcium hypochlorite, or ammonium persulfate) with specific concentrations (0.01-5 wt%). This chemical parameter change enables the composition to effectively interact with the high mechanical strength silicon nitride material, achieving a polishing speed of 0.01-0.1 μm/min while maintaining material integrity.
Solution Approach 2:
The patent creates a composite polishing composition that combines colloidal silica (0.1-10 wt%) as the base abrasive with oxidizing agents. This composite formulation synergistically combines mechanical abrasion from silica particles with chemical oxidation from the added agents, enabling effective polishing of high-strength silicon nitride that conventional compositions cannot achieve efficiently.
2Speed
If etching process is used to remove silicon nitride layer, then polishing speed can be improved, but processing time is prolonged and throughput is lowered
Solution Approach 1:
The patent merges chemical etching and mechanical polishing functions into a single CMP process. The composition simultaneously performs chemical oxidation of silicon nitride and mechanical removal through colloidal silica abrasion, eliminating the need for separate etching and polishing steps, thereby reducing total processing time while maintaining efficient material removal.
Solution Approach 2:
The polishing composition is designed to perform multiple functions: mechanical abrasion from colloidal silica, chemical oxidation from oxidizing agents, and selective removal based on pH control. This multi-functional composition replaces the need for separate etching and polishing processes, improving throughput by combining steps into one operation.
3Manufacturing precision
If conventional composition is used, then polishing can be performed, but selectivity control between different layers is difficult
Solution Approach 1:
The patent introduces dynamic control capability by making the polishing composition's performance可调 (adjustable) through pH control (pH 1-7) and oxidizing agent concentration (0.01-5 wt%). This allows the selectivity between silicon nitride and other layers (metal, oxide insulating) to be dynamically adjusted according to specific process requirements, enabling precise control of polishing speeds for different layer combinations.
Solution Approach 2:
The patent enables selectivity control by changing key parameters: pH value (1-7 range) and oxidizing agent concentration (0.01-5 wt%). These parameter changes allow independent adjustment of polishing speeds for different material layers, achieving desired selectivity ratios without sacrificing overall polishing efficiency or requiring completely different compositions for different applications.
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 significantly enhances the polishing speed of silicon nitride layers while allowing for flexible control of selectivity, enabling efficient processing without altering the silicon nitride layer's speed, thus improving semiconductor manufacturing throughput.
Implementation Method 1
a composition for polishing silicon nitride includes 1) colloidal silica, 2) a polishing aid including a phosphoric acid compound and a sulfuric acid compound, and 3) an oxidizing agent
Implementation Method 2
CMP (Chemical Mechanical Polishing) is an important elemental technique in semiconductor process
Implementation Method 3
CMP covers a large variety of objects to process
Data Source
AI summary
A composition for polishing silicon nitride according to the present invention includes colloidal silica, a polishing aid including a phosphoric acid compound and a sulfuric acid compound. By further including an oxidizing agent, a first selectivity representing the ratio of a polishing speed for a metal layer to a polishing speed for a silicon nitride layer and a second selectivity representing the ratio of a polishing speed for an oxide insulating layer to a polishing speed for a silicon nitride are controlled.