Wafers, substrates for SAW devices
Wafers are thin plates made of synthetic quartz with piezoelectric properties. These are starting product for production of devices on the base of surface acoustic wave (SAW).
We standardly produce wafers with diameters of 3 ”(76.2 mm) and 4“ (100.0 mm). According to customer requirements, respectively a particular application, we supply wafers with various surface qualities - from fine-lapped to polished with SAW quality. As a starting material in addition to the synthetic quartz can be used other piezoelectric crystalline materials such as lithium niobium (LN, LiNbO3), lithium tantalum (LT, LiTaO3) langasit (La3Ga5SiO14) and others.
We standardly produce wafers with diameters of 3 ”(76.2 mm) and 4“ (100.0 mm). According to customer requirements, respectively a particular application, we supply wafers with various surface qualities - from fine-lapped to polished with SAW quality. As a starting material in addition to the synthetic quartz can be used other piezoelectric crystalline materials such as lithium niobium (LN, LiNbO3), lithium tantalum (LT, LiTaO3) langasit (La3Ga5SiO14) and others.
Wafers are used for a wide range of applications, such as
- Components of SAW for the frequency stabilization and filtration (resonators, filters, oscillators)
- Components for sensors with SAW
- Optoelectronic components
- RF Microwave Circuits
- Biotechnic fields
- photolithography technology
etc.
Typical specifications of Quartz Wafers
| Parameter | 3" substrate | 4" substrate | tolerance |
| Diameter [ mm ] | 76.2 |
100.0 |
±0.2 mm |
| Thickness [ µm ] | from 250 to 2000 µm, standard 350 or 500, resp. according to customer specification |
±10 µm | |
| Cut angle | family of ST cuts (rotated Y-cut around the X axis about 25° – 50°), cuts Y90°, Z90°, X90°, ZX 1°50‘, … specials and some double rotated cuts according to customer specification |
±5' | |
| Cut angle marking |
with slots in the main flat, and/or on side of the wafer, by using sec.flats - the size and location by customer, laser description below the primary pad - by customer specification |
||
| The main flat - location - length [mm] |
normally perpendicular to the axis-X 23.5 mm (3“) or 32 mm (4“) or customer specified |
±15' ±1.5 mm |
|
| Surface Quality | fine lapped- typically the back side – Ra = 0,12 – 0,20 µm, optically polished – Ra < 10 nm, polished SAW quality – RMS < 1 nm (different quality for each side can be choosen ) |
||
| TTV [ µm ] | < 8 | ||
| Bow [ µm ] | < 40 | ||
Specifications of synthetic quartz (according to EN/IEC 60758:2004, Ed.3 ):
|
grade C ( > 1.8 x 106 ) grade Ib grade 3 |
Basic Specifications for Quartz wafers for SAW applications
| Parametr | 3" substrate | 4" substrate | Tolerance |
| Diameter [ mm ] | 76.2 |
100.0 |
±0.1 mm |
| Thickness [ µm ] | 250, 350, 500, 550 |
+10/-20 µm | |
| Cut angle | family of ST cuts (rotated Y-cut around the X axis about 25° – 50°) |
±5' | |
| X axis orientation | parallel to the surface | ±15' | |
| The main flat
- length [mm]
|
23 |
32 |
±1.5 mm |
|
- orientation
|
perpendicular to the axis X | ±15' | |
| Cut angle marking | with slots in the main flat, and/or on side of the wafer, by means of sec.flats, laser inscription below the primary flat |
||
| Surface Quality
- polished side - cut side |
polished SAW quality – RMS < 1 nm fine lapped (GC2000) - Ra = 0.12 - 0.20 µm |
||
| Protective bevel
- front side - back side |
the edge of the wafer 0.2 mm 0.025 mm |
+0.2 mm +0.175 mm |
|
| TTV [ µm ] | < 8 | ||
| MaxLTV [ µm ] | < 5 (an area of 13.6 x 13.6 mm) |
||
| Bow [ µm ] | < 40 | ||
Reference
For more information about the quartz crystal can be obtained from the following technical standard:
EN (ISO) 60 758, Synthetic quartz crystal - Specifications and guidelines for use
Wafers dimensions
Outline dimensions [ mm ]
| 3" wafer | 4" wafer |
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