—— For those curious about the essence of technology
1. What is it exactly?
Imagine applying a screen protector to your phone; a single speck of dust can create bubbles on the screen. The requirements for chip manufacturing are a million times more stringent — it is necessary to polish a silicon wafer the size of a fingernail to an “atomic-level mirror finish,” with surface undulations less than 0.2 nanometers (equivalent to the height difference of less than 1 millimeter along the entire route of the Beijing-Shanghai high-speed railway). The miracle of achieving this is attributed to a polishing solution that appears as milky white as milk: an environmentally friendly, non-toxic water-based formulation that can give silicon, metal, and ceramics a mirror-like shine.
2. Ingredient Revelation
The turbid liquid visible to the naked eye is, under an electron microscope, actually a precise collaboration of four major roles:
- • Grinding Particles Silica/Cerium Oxide/Nanodiamonds (20-200 nm) serve as the main force, mechanically leveling microscopic protrusions
- • Chemical Reagents Hydrogen Peroxide + Organic Acids precisely soften the surface, assisting particles in efficiently stripping materials
- • Surfactants Prevent particle agglomeration and sedimentation, maintaining uniform dispersion
- • Ultra-Pure Water Resistivity ≥ 18 MΩ·cm (a thousand times purer than drinking water), eliminating secondary pollution
3. The Principle of Collaborative Operation
The polishing process is like a microscopic construction site:
- 1. → The chemical agent first softens the surface layer (such as the metal oxide layer)
- 2. → The grinding particles then scrape away the softened layer
- 3. → Surfactants maintain scraping uniformity, preventing scratches
- 4. → Ultra-pure water washes away debris, recycled through a filter (≤10 nm)
A delicate balance: excessive chemical corrosion leads to pitting, while excessive mechanical grinding causes scratches; only through their tacit cooperation can a perfect mirror finish be achieved.
4. The Four Major Players Each Show Their Skills
- • Silica Polishing Solution ▪️ Main battlefield: Semiconductor wafers ▪️ Specialty: Nanometer-level flattening (scratches < 0.05/cm²)
- • Cerium Oxide Polishing Solution ▪️ Main battlefield: Optical lenses/Laser optics ▪️ Specialty: Ultra-fine granularity (roughness < 0.1 nm)
- • Diamond Polishing Solution ▪️ Main battlefield: Sapphire/Silicon Carbide substrates ▪️ Specialty: Hardness champion (removal efficiency increased by 3 times)
- • Alumina Polishing Solution ▪️ Main battlefield: Ceramics/Fiber optic connectors ▪️ Specialty: Economical and durable (cost reduced by 40%)
5. The Ubiquitous Mirror Engine
- • Core of Semiconductor Manufacturing 7nm chips require over 20 polishing processes, with polishing solutions accounting for 50% of CMP costs; a 1% increase in yield can add hundreds of millions in annual profits.
- • Foundation of Optical Clarity After polishing AR glasses/automotive LiDAR, light transmittance increases from 92% to 99%, and stray light is reduced by 50%.
- • Essential for High-End Manufacturing After polishing, the roughness of aerospace turbine blades decreases to 0.05μm (originally 0.8μm), increasing fatigue life by 30%.
- • Promoter of Daily Aesthetics Stainless steel kitchenware polished to a gloss of ≥1000GU, also featuring anti-fingerprint properties.
6. Three Directions for Future Evolution
- • Green Upgrade: Fluorine-free biodegradable formula, COD emissions reduced by 70%, wastewater treatment costs halved
- • Precision Customization: 3nm chip-specific liquids achieve selectivity ratios >30:1, with depression control <10nm
- • Intelligent Monitoring: Real-time detection of particle size/Zeta potential, AI pre-warning for polishing defects
- • Domestic Breakthrough: Mass production of 10nm cerium oxide particles, with an annual capacity of 30,000 tons to help reduce costs by 20%
7. The Gentle Power of Technology
This cup of “nano sandpaper” quietly smooths the ruggedness of the microscopic world — when you swipe your phone screen, drive a new energy vehicle, or shoot 4K video, the atomic-level plains beneath the mirror are carrying the precision and order bestowed by the polishing solution.