Notes on the use of the

JANDEL MULTIPOSITION PROBE for 6" WAFERS

General

The equipment can measure wafers up to 6" diameter using a JANDEL probe head.

The wafer is vacuum retained, connection from a pump or vacuum line can be made to the hand-operated valve on the left of the probe.

Pushing the valve control away from the operator opens the valve and retains the wafer.

Operation

There is no interlock on this manual probe, so the probe head must always be raised before the table is rotated or moved radially along its slide. The probe unit is supplied with a probe head in position, correctly set.

The equipment can be connected with the associated electronic measuring equipment by the 9-way plug provided, wiring details are included with the plug and also attached to these notes. Raising the probe operating lever switches off the current via the micro-switch during the "lost motion" and then raises the probe head mounting slide, so that the wafer can be loaded, after pulling the table towards the operator, to the limit of its travel. The table has a "tweezer notch" for convenience of centring the wafer relative to the rings on the table.

1. Measurement at Wafer Centre

The table should be pushed to the limit of its travel away from the operator - at this position the centre of the wafer is immediately below the probe points and if the operating lever is lowered fully, the needles make contact with the wafer, and are fully compressed while the micro-switch switches the current on. Measurement can thus be made at the centre. The operating lever should then be raised so that the wafer can be removed, or measurements made at other radial positions.

2. Measurement at Radial Settings

On the right hand side of the moving table slide are seven screws which blank off holes at 15, 20, 25, 30, 35, 50 and 60mm from the "central" position. Any one, or all screws, can be removed so that the slide can be set at the appropriate radial distance dependent on the wafer diameter. There are four radial settings at 90° intervals denoted on the rotating table by "click" position, so that by raising and lowering the operating lever at each 90° position, four measurements can be made at any set radial distance.

Adjustments

1. The operating lever should be sufficiently stiff in its functioning to hold the probe head fully raised. Adjust the socket set screw in the probe head support immediately above the operating lever shaft, clockwise makes the operation more stiff.

2. Check that when the lever is pulled fully down the micro-switch has operated. The probe needles should make contact with the wafer before the switch operates, if in doubt proceed as for:

Exchanging Probe Head

1. Remove the probe head by slackening the red clamp screw on the left hand side of the probe head mounting, lift out the probe head, unplug the lead.

2. Check the micro-switch setting by pulling down the operating lever so that the slide is fully down, observe that the micro-switch has just operated, if not, correct by adjusting the screw and locking it.

3. Fit a probe head into the mounting, ensuring that the bellows slide up the probe head body. Rotate the probe head so that the needles lie parallel to the front face of the mounting (use the two screws in the probe head as a guide). Position a wafer on the table because its thickness is significant. Pull down the operating handle completely, and then push the probe head down on the wafer until the insulating pad lies on the wafer surface, i.e. the needles are fully compressed, then clamp the probe head firmly with the red clamp screw, do not tighten excessively. Ensure that the micro-switch has just operated. This can be observed by slackening the adjusting screw completely until the switch is obviously not operative, then screw the screw clockwise (down) until the switch clicks. Lock the screw with the hexagon nut. RECHECK.

Note that the range of thicknesses that can be accommodated is at least 0 - 1.5mm. The extra movement of the micro-switch actuator when measuring thinner wafers is absorbed by flexing of the leaf spring.

Verify, once more, the setting of the micro-switch, the alignment of the probe needles, position of bellows, etc. Remove the test wafer.

NB

The probe head can normally be positioned with no wafer on the table, the micro-switch has already been set so that it will function correctly for wafers or specimens up to 1.5mm thick. BE CAREFUL THAT THE PROBE HEAD NEEDLES DO NOT ENTER A GROOVE OR THE CENTRAL HOLE IN THE TABLE.

To Remove Light Shield from Multiposition Probe

  • Slacken clamp screw on left hand side of probe head mounting block. Unplug the probe head and pull it out from the plastic bellows.

  • Slacken and remove the two 6BA cheesehead screws which are holding the hinge to the column. (The right hand screw also earths the screen)

  • Pull the screen forward and remove the two 8BA socket cap screws which secure the lower end of the lifting linkage to the screen. Access to the screws is best through the probe head mounting block using the long end of the key.

  • Remove the screen and also unhook the small block from the linkage.

  • Note that the link chain can be left to hang, or taped to the underside of the column.

    • To Replace Light Shield

    Reverse 1 - 5 above.

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