Glass Wafers

Schott® Borofloat® 33 Borosilicate Wafers

Material Description

The performance requirements for wafers used for anodic bonding or as a carrier in wafer thinning processes are mainly determined by their ability to perfectly match those of the silicon wafer to which they shall be bonded. Well-adapted thermal expansion behavior is as important as excellent flatness and process robustness. BOROFLOAT 33 glass wafers provide these along with exceptionally high UV transmission.

Glass Wafer Options

Coresix produces Schott® BOROFLOAT 33 wafers to all SEMI Standards including dimensional, flat and notch specifications. In addition, we offer custom specifications designed to your unique needs including, alignment marks, holes, pockets, edge profile, thickness, flatness, surface quality, cleanliness or other details critical to your application.

Wafer Specifications

Attribute Standard Best
Diameter 50.8, 76.2, 100, 150, 200, 300, 450 Custom Diameters
Diameter Tolerance +/- 200μm +/- 50 μm
Thickness .7, 1.1, 1.75, 2.25, 2.75, 3.3 Custom .45mm - 1.1mm
Thickness Tolerance +/- 5% +/- 5 μm
Thickness Variation (TTV) <20μm <1μm
Scratch and Dig 60/40 5/2
Roughnes (RMS) <7Å <3Å
Warp <400μm <30μm
Flatness λ per Inch TIR λ/10 per Inch TIR

Electrical Properties

Dielectric Strength (25°C,  50Hz) 16 kV/mm
Dielectric Constant (25°C,1MHz) 4.6
Loss Tangent  (25°C, 1MHz) 37 x 10-4
Electric Volume Resistivity (250°C) 8.0
Electric Volume Resistivity (350°C) 6.5

Mechanical Properties

Density (25°C / 77°F) 2.23 g/cm3
Modulus of Elasticity 63 kN/mm2
Young's Modulus (25°C / 77°F) 64 kN/mm2
Knoop Hardness HK 0.1/20: 480
Poisson's Ratio 0.2
Bending Strength 25 MPa

Thermal Properties

Thermal Coefficient of Expansion (20-300°C) 3.25 x 10-6 K-1
Specific Thermal Capacity (20-100°C) 0.83 KJ x (kg x K)-1
Specific Thermal Conductivity (90°C) (1.2W x (m x K)-1
Annealing Point 560°C / 1040°F
Softening Point 815°C / 1508°F
Thermal Conductivity 1.2 W/mk @90°C
Maximum Operating Temperature Considering
RTG (Resistance to Thermal Gradients) and RTS (Resistance to Thermal Shock)
Short Term 500°C  / 932°F
Long Term 450°C  / 842°F

Optical Properties

Refractive Index 1.471
Index of Refraction  
@435.8nm 1.48
@589.3nm 1.47
@656.3nm 1.46
Dispersion 71.4 x 10-4
Abbe Constant 65.41
Schott® Borofloat® 33 Borosilicate Wafers Optical Transmission