Glass Silicon Constraint Substrates

Corning supplies a variety of polished and machined glass wafers for use in the fast-growing MST/MEMS 
(Micro Systems Technology/Micro-Electrical-Mechanical Systems) technologies.

The substrates are produced using the

industry standard 

Pyrex

®

(Corning code 7740) and other silicon thermal

expansion matching glasses, such as Corning code 7070; coupled with innovative manufacturing techniques, 
world class measurement, and global sales and technical support.

Materials:

Pyrex

®

7740 Borosilicate Glass

7070 Lithia Potash Borosilicate

Glass Properties:

7740

7070

Mechanical

Density (g•cm

-3

)

2.23

2.13

Young Modulus (G Pa)

62.75

51.00

Poisson Ratio

0.20

0.22

CTE, 0-300°C (x10

-6

•°C

-1

)

3.25

3.20

Viscosity

Working Point (°C) 10

4

Poise

1252

1068

Softening Point (°C) 10

7.6

Poise

821

n/a

Annealing Point (°C) 10

13

Poise

560

496

Strain Point (°C) 10

14

Poise

510

456

Electrical

Log volume resistivity (

Ω

cm): 250°C, 350°C

6.1, 4.6

11.2, 9.1

Dielectric Constant, 20°C, 1MHz

4.6

4.1

Loss Tangent, 20°C, 1 MHz (%)

0.5

0.06

Standard Diameters:

SEMI standard wafer diameters:

75.0mm +/- 0.5mm

100.0mm +/- 0.5mm
125.0mm +/- 0.5mm 
150.0mm +/- 0.5mm

Other shapes and sizes (for example, rectangles) will be quoted upon request
Drilled or machined wafers are also available upon request

Standard Thickness:

1.0mm +/- 0.025mm
0.5mm +/- 0.025mm

Orientation Flats:

SEMI standard flats will be quoted upon request

Edge Beveling:

Standard for 1.0 and 0.5mm thick wafers

Warp:

Less than 20 microns

Total Thickness 
Variation (TTV):

Less than 20 microns

Surface Finish:

Both sides polished to Ra < 15Å typical
Inspected under intensive light (approximately 1500 lux) for scratches and cracks; 
top and bottom surfaces - no faults found

Inclusions:

No inclusions greater than 0.3mm diameter allowed
No open inclusions or bubbles

Edge Chips:

No chips greater than 1.0mm diameter

Packaging:

“Coin Stack” canister, foam packed at each end
Wafers interleaved with lint free spacers
25 wafers per canister

Wafer cassettes or carriers are available at additional cost

Hole Drilling Guidelines:

Feature location

+/- 0.05mm

(Typical)

Minimum hole diameter

0.25mm

Hole diameter tolerance

+/- 0.05mm

Matrix hole pitch, minimum

1.5 x hole diameter

Specialty Lighting & Materials

Houghton Park C-8
Corning, NY 14831

Phone: 607-974-9000
Fax: 607-974-7618

E-mail: waferglass@corning.com
Internet: www.slam.corning.com

Thermal 
Expansion

Corning 7070
Corning 7740 &
<110> Silicon
Cooling Curve

1M 20.82 6/99 Goff