CMP Cleaning Composition for Cerium Removal Without Substrate Damage
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Solution Overview
Problem
Current cleaning solutions for semiconductor substrates after chemical mechanical polishing (CMP) either damage the substrate, require high toxicity, or are inefficient, especially in removing cerium compounds, and often necessitate harsh conditions that are not compatible with existing equipment.
Innovation Solution
A cleaning solution composition containing inorganic acids with fluorine atoms, a reducing agent, and anionic surfactants, which operates at a pH below 7, effectively dissolving and removing cerium compounds without damaging the substrate, and can be used in a brush-scrub cleaning chamber ancillary to a CMP device at room temperature within minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrofluoric acid or strong acid-water system is used for cleaning, then cleaning performance is improved, but substrate damage and equipment corrosion occur
Solution Approach 1:
The invention changes the chemical parameters of the cleaning solution by using inorganic acid salts (fluoride, sulfonate, carboxylate) instead of strong mineral acids, and controls the pH within a specific range (1-6) to achieve effective cleaning while preventing substrate damage. This parameter optimization resolves the contradiction between cleaning effectiveness and substrate safety.
Solution Approach 2:
The invention uses readily available inorganic acid salts that can be easily prepared and disposed of, replacing expensive and hazardous hydrofluoric acid systems. The cleaning solution can be used at moderate temperatures without requiring specialized equipment, making it a practical short-term solution that doesn't compromise long-term substrate integrity.
2Reliability
If hydrofluoric acid is used to remove cerium compounds, then cleaning performance is improved, but toxicity and safety issues increase
Solution Approach 1:
The invention replaces highly toxic hydrofluoric acid with safer inorganic acid salts such as ammonium fluoride, sodium fluoride, or potassium fluoride. These alternatives provide effective cerium compound removal through chemical reactions that form soluble complexes, while being significantly less hazardous to handle and dispose of.
Solution Approach 2:
The invention introduces inorganic acid salts as intermediary substances that mediate between the cleaning objective and safety requirements. These salts act as intermediate agents that can effectively dissolve cerium compounds through complex formation while maintaining a safety profile suitable for standard semiconductor manufacturing environments.
3Reliability
If sulfuric acid at high temperature is used for cleaning, then cleaning performance is improved, but equipment corrosion and processing time increase
Solution Approach 1:
The invention changes the temperature parameter from high (120-150°C required for sulfuric acid) to moderate (room temperature to 60°C sufficient for inorganic acid salts). This temperature reduction is achieved by using chemically more reactive inorganic acid salt formulations that don't require thermal activation, thereby preventing equipment corrosion while maintaining cleaning effectiveness.
Solution Approach 2:
The invention substitutes the thermal-mechanical cleaning approach (high temperature sulfuric acid) with a chemical solution approach using inorganic acid salts. The cleaning mechanism shifts from thermally-driven to chemically-driven, eliminating the need for high-temperature equipment and reducing mechanical stress on cleaning system components.
4Reliability
If ammonia-hydrogen peroxide solution is used for cleaning, then cleaning performance is improved, but treatment time and working environment issues increase
Solution Approach 1:
The invention optimizes the chemical composition parameters by using inorganic acid salts with specific pH ranges (1-6) and appropriate concentrations. These formulations achieve effective cerium compound removal through direct chemical reactions that proceed rapidly at room temperature, reducing treatment time compared to ammonia-hydrogen peroxide systems that require longer contact times and generate offensive odors.
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 solution provides high removal performance against cerium compounds without damaging silicon oxide, silicon nitride, or silicon surfaces, is safe to use, and compatible with CMP device equipment, improving cleaning efficiency and yield while reducing equipment erosion.
Implementation Method 1
A cleaning solution composition containing inorganic acids with fluorine atoms, a reducing agent, and anionic surfactants, which operates at a pH below 7, effectively dissolving and removing cerium compounds
Implementation Method 2
A cleaning solution composition containing inorganic acids with fluorine atoms, a reducing agent, and anionic surfactants
Implementation Method 3
A cleaning solution composition containing inorganic acids with fluorine atoms, a reducing agent, and anionic surfactants
Data Source
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AI summary
Provided is a cleaning solution composition which, when cleaning the surface of a semiconductor substrate or glass substrate, does not damage SiO2, Si3N4, Si, and the like forming a layer on the substrate surface, can be used under processing conditions applicable to a brush scrub cleaning chamber equipped with a CMP apparatus, and can efficiently remove compounds derived from abrasive particles in a slurry. This cleaning solution composition for cleaning the surface of a semiconductor substrate or glass substrate contains: one or two or more fluorine atom-containing inorganic acids or salts thereof; water; one or two or more reducing agents; and one or two or more anionic surfactants, and has a hydrogen ion concentration (pH) of less than 7.