ACS Integrated Test System for Multi-site Parallel Testing (Part 2)

The most easily thought of multi-site tester is a mini-tester system. Each mini-tester contains all the resources needed to run a series of tests at a site. Figure 3 shows a system consisting of two mini-tester. Each mini-tester contains several analog source-measure units (SMUs), a test sequencer/controller, and an optional switch matrix. Independent controllers allow each mini-tester to operate independently of the other mini-tester and the system controller. In this way, the system controller does not gate the test runs, but instead initiates the test sequence and organizes the test data generated. Keithley's ACS Integrated Test System supports the mini-tester architecture with Keithley's Series 2600 SourceMeter instruments. Using TSP-LinkTM patented scalable virtual backplane technology and embedded scripting, several Series 2600 devices can be grouped into mini-tester. The distributed nature of the mini-tester can greatly increase throughput. Using true parallel testing, the time it takes to fully test the four FET test station in Figure 2 is less than the time it takes a sequential tester to complete the first test of the four FETs (as shown in Figure 4).

Figure 3. Parallel test system architecture

 Figure 4. Comparison of sequential and parallel testing.

Easy to use

When executing a parallel test project, test engineers face several potential challenges. These include setting up test sequences and executing tests in a fully automated prober environment. Keithley’s Automated Characterization Suite (ACS) software (Figure 5) addresses these challenges with an intuitive user interface that provides: • Wafer description • Test setup • Probe control • Automation • Summary reporting ACS enables high-throughput parallel testing of wafers from all cassettes by implementing cassette-level and wafer-level automation. ACS also includes real-time binning and plotting capabilities (Figure 6).

Figure 5. The parallel testing feature of the ACS test setup user interface makes programming the Series 2600 as easy as point, click, and enter test parameters.

Figure 6. The ACS automatic monitoring screen displays the grading results in real time using color codes.

in conclusion

Increased time-to-market and test cost pressures mean test engineers must do more with less. With Keithley's proven instruments and measurements, the ACS Integrated Test System fills the gap between interactive lab-based tools and high-throughput production test tools. The ACS Integrated Test System, shown in Figure 1, is ideal for multi-site parallel testing of die sorting, advanced reliability, and other high-throughput applications. The 2600 Series instruments feature high-speed parallel testing capabilities using distributed test sequencing capabilities enabled by embedded test script processing.