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Align wafer#

A test that can be used to automatically align a wafer handled by a probe station.

Description#

The test is used for automatically aligning a wafer handled by a probe station. The alignment requires an taught procedure at the probe station, ideally saved within a probe station project. The algorithm starts by moving to the taught position of the initial pattern, searching within the Field-of-View (FoV) and pre-align the wafer. Subsequent the algorithm steps relatively by Die-Size and searching for the next pattern within the FoV. Once the second pattern is found, the procedure steps to the calculated edge of the wafer searching for the furthermost pattern to perform an accurate alignment with the full wafer size.

Requirements/Conditions:

  • Auto-Alignment requires a grid of at least 2x2 dies/pattern
  • Auto-Alignment requires a unique pattern taught at the probe station software and existence on every die
  • The algorithm does not update or change the die size taught in the probe station software
  • The algorithm will execute the alignment at the current probe site - On-Axis or Off-Axis
  • The algorithm can only align the wafer within the probe station theta limits (typically ± 5 degree)
  • Timeout-value using the probe station defaults
  • MPI SENTIO Software Suite: 18000ms

Input parameters#

The test requires to select a probe station, added in the device manager.

Output parameters#

The test does not provide output parameters.

Supported devices#

The following devices are supported by this test:

  • MPI SENTIO Software Suite

Example#

Hardware setup:

Connect a wafer prober to the computer running Measmatic over TCP/IP, GPIB or RS232. 

flowchart LR
    A(Measmatic) o---o |TCP/IP, 
    GPIB or 
    RS232| B(Wafer prober)

In the device manager add the wafer prober to the current test site configuration. Change the name, the IP address in the device properties of the device. If needed, increase the communication timeout for the probe station device.

Software setup:

Teach a pattern within the Autoalign-Wizard at the probe station software and setup the correct die size. Ideally the pattern and values are saved in a probe station project.