NI Gold Alliance Partner 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 replaces an expensive 20-year-old Teradyne tester and has reduced test time by 50 percent.
The system tests voltage, current, resistance, and pressure for individual sensor die on a silicon substrate. There are currently five separate test points per sensor, and the tester is configured for up to 20 test points per sensor. Currently, 15 parameters are being tested per die.
Increasing production throughput is a common challenge for any wafer probe operation. Using old equipment that is not readily expandable and configurable only complicates the problem. To expand probe capacity and have a dynamic and configurable test system, a silicon sensor manufacturer contracted G Systems to design an automated wafer probe tester that increased test flexibility and reduced total test time by more than 50 percent.
A System based on NI Hardware
The G Systems wafer probe tester uses NI hardware to interface between a vintage Electroglas prober and four high-speed, high-sensitivity source measure units (SMUs). The signals are routed through the high-density NI PXI-2532 512-crosspoint matrix switch module configured in an 8 x 32 two-wire array. The NI PXI-4070 FlexDMM measures voltage and sensor leakage.
LabVIEW for Control and Operator Interface
LabVIEW controls the system, sequences parametric tests, and updates results in a database. Each sensor type has an executable test program and a unique configuration file. This software architecture made it simple to modify test parameters and adjust test limits making changes in the code. The test software and files are downloaded on demand from a remote, secure file server. With NI Switch Executive, we could easily route all signals between the SMUs and the wafer through the prober.
We developed the test software with an operating mode for production testing and an engineering mode. In engineering mode, the software provides access to additional controls and test data, and a technician can step through the individual tests one at a time and pause on request.
A configurable, high-speed PXI-based automated wafer probe tester was developed, which reduced test time by more than 50 percent. A LabVIEW software program provided a simple, operator-friendly test solution that is configurable for multiple test limits and multiple sensor types. Overall, test times were reduced at significant cost savings.
G Systems, LP
860 Avenue F, Suite 100
Plano, TX 75074
Tel: (972) 516-2278
Fax: (972) 516-2286