SussPA300UserGuide - 第39页

38 SUSS / PA300 / User Manual / M10-121841-00 / February 2002 8 User Maintenance 8.1 General Maintenance The short time spent performing a short visual inspection will greatly improve the overall performance of the syste…

SUSS / PA300 / User Manual / M10-121841-00 / February 2002

Platen Cable Clamps

Cable clamps are provided to secure electrical connections and/or vacuum hoses.

Chuck Stage

All stage movements are DC servo motor driven with encoder positioning feedback.

Stage control is from the ProberBench User Interface or Joystick Controller. No manual

controls are required.

Vacuum Hold-down Adjustment

The vacuum chuck has provisions to adjust the vacuum hold-down for various size

wafers. To change the wafer size, unscrew and remove the current seal-pin. Insert

and screw in the appropriate length seal-pin. The unused seal-pins are usually stored

on the front left hand side of the system.

Chuck Grounding and Biasing

The chuck is isolated from ground and a lead is provided from the chuck to a banana

jack at the right rear corner of the prober mechanic. At this point the jack can be

connected to ground with the ground jack provided, or connected to a bias voltage

source.

Pin Drive

The pin drive is integrated into the Z-Axis and because the pins are fixed, one controls

them with the movement of the Z-Axis, an automatic interlock prevents damage

occurring to the wafer. If the wafer is lying on the chuck and held by vacuum, the

movement of the Z-Axis is restricted so that the pins stay in the chuck. After switching

off the vacuum, the chuck can be driven as far as the wafer unloading height and the

pins stand finally about 5-6mm away.

SUSS / PA300 / User Manual / M10-121841-00 / February 2002

8 User Maintenance

8.1 General Maintenance

The short time spent performing a short visual inspection will greatly improve the overall

performance of the system. Furthermore, be alert at all times to any unusual system

noises, behavior or changes in operating performance or the results which may be

symptomatic of problems which could damage the system if left uncorrected.

8.2 Visual Checks

It is very important to conduct a thorough visual check of the system on a daily basis.

Key areas include the chuck surface, movements of the wafer stage x, y, z and theta,

microscope stage X and Y, platen and the individual probeheads. All movements should

exhibit smooth transit without any irregularities. Also inspect for scratches and other

signs of wear and tear. A poorly maintained instrument will not meet designed

performance specifications.

8.3 Safety Interlock Switch

The safety interlock switch can be found underneath the probe head platen, on the left

side of the long rotational axis of the covering lid. The operator is obliged to carry out

tests on this switch at least every 6 months.

8.4 Mechanical Adjustments

These maintenance procedures will help to ensure system accuracy and reliability.

8.4.1 Chuck Planarizing Procedure

If upgrading with a thermochuck through SUSS, planarization will be undertaken by

qualified SUSS personnel or representative

Chuck planarizing or levelling ensures equal probe contact force from tip-to-tip of

probecards and throughput the range of travel of the chuck. It has been planarized at

the factory and checked, and adjusted if required, at installation. It generally will not

become unplanarized with use, but if you notice that at high magnifications the chuck

goes out of focus in areas of the chuck, planarization is required. If the chuck has been

removed or changed planarization should be checked.

Procedure

1. Remove both halves of the black cover on top of the chuck stage. Use the joystick

to move the chuck for access to the screws and clearance to remove the covers.

Do not remove the safety covers!

SUSS / PA300 / User Manual / M10-121841-00 / February 2002

2. Planarization can be measured with a dial indicator or with the microscope. This

procedure will rely on the microscope, which when used with a 50x objective (500x

total magnification) provides a 2 micron depth of focus.

3. The chuck level will be checked near the edge of the chuck and in-line with each

levelling screw, which are approximately at each corner. You can move to these

positions with the joystick or enter the positions in a TableView file and click on

each site to quickly move to it.

4. Move to each of the three sites and determine which one is the lowest by noting if

the microscope was raised or lowered to focus. The lowest will be the reference

point (site #1) to which the other two will be adjusted. The lowest is used to maintain

maximum spring pressure of the levelling mechanism.

Note: Planarization is done with the chuck surface, not a wafer which may

not be planar.

5. Move to site #1 and focus using the microscope.

6. Move to site #2 and adjust the chuck levelling screw at this site so the chuck is in

focus. Do not focus using the microscope.

7. Move to site #3 and adjust the chuck levelling screw at this site so the chuck is in

focus. Do not focus using the microscope.

8. Repeat steps 5 through to 7 until all three sites remain in focus.

9. Reinstall stage covers.

8.4.2 Platen Levelling Procedure

Set screw

Levelling screw

Note: This procedure should be performed only after the chuck has been

properly planarized or levelled.