GM.SI Series

The GM.SI Series X-ray orientation systems are heavy duty production units especially designed for locating the flat or notch position on all kinds of single crystals, from the smallest to the largest size. All single crystal can be processed, for all applications such as semiconductors, opto-electronics, optics, etc.

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■ Orientation processes

Flat & Notch on "as grown" ingots
Flat & Notch on ground ingots (cylindrical)

■ Orientation measurements

Ingot flat
Ingot notch
Seed axis (round or square seeds, with optional holder)
Wafer face
Wfaer flat (optional holder)

■ Performance

X-ray detection : ± 0.01°
Orientation process : ± 0.03 to 0.05°, depending of configuration and crystals.
Measurements : ± 0.01° to 0.03°

Configurations

The GM.SI-…-R type X-ray orien- tation systems are specific models of our GM.SI series X-ray units, specifically designed for operation in combination with grinding equipment where the ingot is hold between centers, and the grinder spindle equipped with rotation control and display.

Like all models of the GM.SI series, the GM.SI-…-/R models are available as a single station unit or in dual-station mixed configurations.

This can be in combination with either a GM or a GM.WS series work station.

Goniometer

An extremely robust goniometer assembly supports the complete ingot handling mechanism. The goniometer shaft incorporates a specimen holder which is used as a reference plane for easy calibration of the equipment, measuring wafer orientation and for mounting optional holders.

A reference roller having its edge in the same plane as the holder is mounted directly on the shaft.

Goniometer / detector rotation range : <0° to ca. 100°

Capacities

GM.SI models are available in several capacities which are configured according to the user's requirements. They cover a complete range of applications from diameter 2-inch up to 200 mm and 800 mm in length.

A dedicated model is available for ingots of diameter 300 mm.

(specific documentation on request)

Angle reading

Digital angle display in decimal degrees (0.01°), in deg. min. sec (optional) or through a PC.

Reset to zero at any position

Absolute or relative angle value can be alternatively displayed

Automatic recalibration at start-up or at any time.

Safeties and protections

The equipment has been designed to offer both maximum protection and easy operation.

Electromagnetic rotary shutter controlled by a non latching foot switch.
Shutter interlock switch actuated by the ingot in measuring position
Green / Red control lights : indication of shutter status.
"X-ray ON" light with automatic equipment shut-off in case of lamp failure.
Shields and screens stop direct or scattered radiation

X-ray generator

Output voltage : 30 kV – DC
Maximum rating : 30 mA
X-ray tube : copper target, water cooled
Apparent focus : linear fine focus
Mains : 220 V 50/60 Hz, 1-phase, 10 A
Water supply : 2.5 bar. Flow rate 3.5 l/min

Detection unit

Proportional counter linked to a special integrator with peak amplifier, giving a high detection accuracy.

Voltage is adjustable from 1000 to 1850 V

Voltmeter and adjustment potentiometer are located in the casing facing the operator

The easiest and most accurate way of grinding a flat or a notch on an ingot at the proper orientation is provided when the same ingot holding and orientation transfer system is used on both the X-ray goniometer and the flat/notch grinder.

Additionally, best results are obtained when the orientation established on the goniometer can be transferred to the grinder simply by setting its spindle rotation angle at a given value. This is achieved when the goniometer is fitted with angular display of the ingot rotation and the grinder with angular display of the spindle rotation.

Ingot holding system

The ingot (fitted with two steel centering pieces) is hold between two ball centers. Up and down motion of the upper center assembly on a rigid column is pneumatically controlled with foot operated switches, thus leaving the hands free.

The above assembly is mounted on a pneumatically controlled sliding work-table which brings and maintains the ingot in contact with the reference roller, regardless of ingot diameter and shape (as grown ingots). The beam focuses at the contact point between ingot and roller.

Ingot rotation

The upper center ball assembly is part of a rotating cylinder which also incorporates a reference pin. The pin is spring loaded. The rotation angle of the cylinder is displayed digitally, in the same way as the goniometer rotation itself.

A pneumatically actuated fine rotation control and brake system enables accurate rotation control of the ingot at any position.

Ingot orientation process

Affix a centering piece with slot at the ingot upper end, and a centering piece without slot at the bottom end.
Place the ingot between the goniometer ball centers, the reference pin of the upper assembly latching into the slot of the centering piece.
Proceed to ingot orientation by rotating the ingot until a reflection peak is obtained. Use the fine rotation control to get an accurate orientation.

Note the value displayed on the "ingot rotation" display.

Place the ingot on the grinder, the index pin latched into the slot of the piece.
After the ingot OD has been ground, rotate the grinder spindle until its rotation display indicates the same value as the one noted.
Proceed to flat or notch grinding, then to the secondary flat when required.

Upper rotating assembly with angle encoder, ball center, latch pin and fine rotation control.

A - GM.SI-…-/R goniometer

B - Grinder with compatible holding

system and rotation angle display

1 - Goniometer angle display

2 - Ingot rotation angle display

3 - Grinder spindle rotation angle display

4 - Lower ingot centering piece

5 - Upper ingot centering piece

Orientation measurements

Ingot Flat & Notch

After grinding, the ingot is placed again on the goniometer and the flat or notch checking device brought and maintained in contact against the flat or against the notch of the ingot.
The goniometer fine control knob is rotated until a reflection peak is obtained. The goniometer angle readout system directly displays the grinding error.

Wafer flat

An easily adaptable dedicated holder is available, which can be placed and removed without the need of resetting or recalibrating the equipment. (See picture below)

Seed axis