Applications of platelet aluminum oxide in the semiconductor industry

Applications of platelet aluminum oxide in the semiconductor industry

Platelet aluminum oxide refers to particles that are flat, have smooth edges, and a controllable aspect ratio (10~150:1). It also has the characteristics of high hardness, high insulation, high thermal conductivity, chemical inertness, and low scratch resistance. It covers five core scenarios: wafer grinding and polishing, thermal insulation of packaging, power device substrates, ceramic parts of semiconductor equipment, and dielectric slurry filling. It is a key powder material for advanced processes and third-generation semiconductors.

I. Wafer Processing: Grinding and CMP (Chemical Mechanical Polishing)

1. Rough grinding of silicon/silicon carbide/sapphire substrates, with thinning of the back side.

Rough grinding of silicon wafers after cutting: 1~5μm platelet aluminum oxide to quickly remove the cutting damage layer; sliding cutting of flat particles reduces micro-cracks on the edge of the silicon wafer, reduces wafer warpage and fragmentation rate, and improves yield.

3D IC ultra-thin wafer thinning: Platelet aluminum oxide grinds the wafer to 50~100μm; compared with spherical/sharp-cornered corundum, the subsurface damage layer is thinner, which is suitable for TSV silicon through-hole process; high-purity low sodium (Na<1ppm) formula avoids copper interconnect contamination.

Third-generation semiconductor substrates (SiC/GaN/sapphire): Silicon carbide and sapphire have extremely high hardness, and their flat morphology significantly reduces surface scratches and pits, making them suitable for mirror pretreatment before epitaxy of power devices.

2. CMP polishing slurry core abrasive

1. Metal interconnect polishing (copper/tungsten barrier layer Ta/TaN): The mainstream abrasive for copper wiring CMP, platelet aluminum oxide combined with H₂O₂ oxidant; the flat particles cut evenly, the metal removal rate can be controlled, and the dish-shaped depressions and corrosion defects are reduced.

2. Shallow trench isolation STI polishing: platelet aluminum oxide is compounded with colloidal SiO₂ to control the silicon oxide/silicon nitride polishing selectivity ratio; flat particles ensure overall flatness and avoid scratches on the trench sidewalls.

3. Sapphire Window / Optical Wafer Polishing: The platelet aluminum oxide alkaline polishing slurry is highly stable and recyclable; it achieves a high removal rate while maintaining a nanoscale roughness Ra<0.5nm, making it suitable for polishing photolithography windows and LED sapphire substrates in mass production.

II. Semiconductor Packaging: High Thermal Conductivity Insulating Filler 

The two-dimensional structure of platelet aluminum oxide is its core advantage: the contact between the sheets makes it easy to build a continuous thermal conductivity path inside the resin. Under the same filling amount, the thermal conductivity is significantly higher than that of spherical alumina, while maintaining excellent electrical insulation and low thermal expansion to match the chip substrate.

1. Thermal interface materials (TIM) (thermal pads / thermal grease / thermal gel)

Platelet aluminum oxide is used for heat dissipation in CPUs, GPUs, IGBTs, SiC power modules, and 5G RF chips.

Platelet aluminum oxide filler: Increases the thermal conductivity of silicone to 1.5~4 W/m・K;

The compound formulation (platelet aluminum oxide + spherical aluminum oxide): small spheres fill the gaps between the lamellar layers, improving thermal conductivity by more than 25%, while balancing high thermal conductivity with slurry flowability; flat alumina provides high insulation, resistance to high and low temperatures, and voltage resistance, meeting the high-voltage isolation requirements of power devices.

2. Epoxy potting compounds, molding compounds, and fillers

Power devices and automotive chip packaging epoxy resin with added platelet aluminum oxide:

1. Improve overall thermal conductivity and quickly dissipate Joule heat from the chip;

2. Adjust the coefficient of thermal expansion (CTE) of the composite material to match silicon/silicon carbide and reduce delamination cracking during thermal cycling;

3. High insulation and low ionic impurities prevent leakage and electrochemical corrosion during encapsulation;

4. It can replace some boron nitride and aluminum nitride, significantly reducing the cost of high-end packaging materials.

3. Bottom filler glue

Flip Chip BGA and FCBGA Filled with platelet aluminum oxide: Platelet aluminum oxide improves the thermal conductivity of the adhesive layer, while also enhancing the mechanical strength and thermal shock resistance of the adhesive film.

III. Thick film/thin film circuits, dielectric paste-filled platelet aluminum oxide

1. DBC/AMB Ceramic Substrate Dielectric Paste

IGBT and SiC power module alumina ceramic substrates, with micron-sized platelet aluminum oxide added to the dielectric paste:

Improve the density and flexural strength of ceramic substrates; plate-like crystals achieve crack deflection and toughening, inhibiting thermal cycling fracture of the substrate.

Adjusting dielectric constant and insulation withstand voltage improves the radio frequency stability of the substrate;

Optimize the leveling properties of the paste for a smoother surface after printing.

2. High-temperature thick-film circuits (RF, sensor chips)

Printed resistors and insulating dielectric layer fillers: Platelet aluminum oxide improves film density, thermal conductivity and insulation reliability, and reduces high-frequency signal loss.

IV. Alumina ceramic structural components for semiconductor equipment (dense platelet aluminum oxide ceramic)

1. Top electrode plate of plasma etching machine: isolates radio frequency electrodes and withstands fluorine/chlorine plasma bombardment; high resistance to plasma corrosion, high insulation, low thermal deformation, dimensional stability at 200~500℃, and machining accuracy ±0.01mm.

2. Cavity dielectric window, insulating isolation sheet, wafer carrier pad: isolates plasma, insulates radio frequency energy, ensures uniform heat transfer, and protects the metal components of the equipment from high-energy ion corrosion.

V. Other Sub-Semiconductor Applications

1. Chip Carrier / Heat Dissipation Ceramic Toughening Phase: A platelet aluminum oxide second phase is introduced into alumina ceramic to toughen and reinforce it, solving the problems of high brittleness and easy edge chipping of pure alumina, and improving the service life of power substrates.

2. Semiconductor precision molds and jigs grinding consumables: Flatelet aluminum oxide for mirror polishing of probe cards, packaging molds, and metal lead frames, with low scratches to ensure device precision.

3. High insulation and thermal conductivity coating: The filler for the insulating and thermally conductive coating of chip heat dissipation substrate and power device shell is platelet aluminum oxide, which takes into account both insulation and heat dissipation as well as weather resistance.

Industry Trends

The demand for high thermal conductivity, low damage, and high insulation materials is booming in third-generation SiC/GaN power devices, automotive semiconductors, and advanced packaging (2.5D/3D ICs). Platelet aluminum oxide, as a domestically produced alternative powder, is gradually replacing imported high-end polishing abrasives and thermally conductive fillers, and is a key incremental material in the semiconductor heat dissipation and wafer planarization track.

PS:Haixu Abrasives produces platelet aluminum oxide with parameters comparable to those of FUJIMI in Japan.

Chemical Composition

Physical Properties

PSD(Particle Size Distribution)