Spotlight - Automated Wafer Probe Tester

The Challenge:
Increase wafer probe test throughput and improve tester flexibility for use with various semiconductor sensors.

The Solution:
Design and build an automated production test system with high speed switching that is configurable for multiple specification limits using LabVIEW™-based software, Agilent Technologies source/monitor units, and NI Switch Executive™.

G Systems developed an automatic test system to test pressure transducers at the wafer level. The tester is fully expandable and features complete DC parametric analysis including functional tests. The new system replaced an expensive, 20-year old Teradyne tester and has reduced test time by 50%. The system tests voltage, current, resistance, and pressure for individual sensor die on a silicon substrate. There are currently 5 separate test points per sensor, expandable up to 20 test points per sensor. Currently 15 parameters are being tested per die.

Hardware: The G Systems Automated Wafer Probe Tester features an Agilent Technologies E5260A High Speed Measurement Mainframe with four E5291A Source Monitoring Units (SMU’s) capable of DC current measurements down to femptoamps.

The G Systems Automated Wafer Probe Tester also utilizes NI hardware to interface between a vintage Electroglas™ prober and the SMU’s. The signals are routed through NI’s High Density PXI 2532 512-Crosspoint Matrix Switch configured in an 8X32 two-wire array.

The PXI 4070 flex DMM measures voltage and sensor leakage.

LabVIEW Software for control and operator interface:
The system is controlled with LabVIEW software to sequence parametric tests and update results to a database. Each sensor type has an executable test program and unique configuration file. This software architecture makes it simple to modify test parameters and adjust test limits without having to make changes in the code. The test software and files are downloaded on demand from a remote, secure file server.

The test software was developed with an operating mode for production testing as well as an engineering mode. In engineering mode, the software provides access to additional controls and test data. Furthermore, in engineering mode, a technician can step through the individual tests one-at-a-time and pause on request.

Conclusion:
A highly configurable, high speed PXI-based Automated Wafer Probe Tester has been developed which reduces test time by over 50%. A LabVIEW software program provides a simple, operator-friendly test solution, configurable for multiple test limits and multiple sensor types. Overall, both test times and equipment costs have been significantly reduced.