Modular instruments provide a flexible, scalable way to test semiconductors—some of these individual instruments are described in a recent EE special report.1 However, some modular-instrument vendors will put together subsystems or complete turnkey systems, along with software and DUT interfaces, that you can easily deploy. For example, Marvin Test Solutions builds systems based on its PXI instruments and ICEasy semiconductor-test software toolset. And Aeroflex offers a variety of systems and subsystems based on its own and—as required—third-party PXI and AXIe instruments.
And at NIWeek 2014, National Instruments adopted a turnkey approach with the introduction of the NI Semiconductor Test System (STS) series (Figure 1), which supports automated test of RF and mixed-signal devices. But despite the turnkey flavor of the new system, which integrates with handlers, for example, Luke Schreier, senior group manager of test systems, emphasized that the systems are based on the open-architecture PXI platform and are fully accessible to the customer. The approach, he said, is particularly beneficial for customers with RF and mixed-signal test needs.
|Figure 1. NI STS |
Courtesy of National Instruments
Speaking at NIWeek, Rebeca Jimenez, vice president for worldwide test operations at Integrated Device Technology, and Glen Peer, director of test at IDT, described their early use of the NI STS. Jimenez said IDT offers devices serving key areas including communications infrastructure, high-end computing, wireless power, and timing. “The main challenge is reducing the cost of test while increasing our factory utilization,” she said, “and one way to do that is by driving a common test platform.”
Peer said, “We are in a unique situation because we purchase hardware from nearly every big iron ATE vendor out there. We’ve also built our own fully custom systems in-house. Big iron, he said, typically requires a large capital investment, and it’s difficult to enhance turnkey systems when needs change. As an alternative to big iron, he said, IDT began to build its own systems. “But we soon learned that the drawback with those is that there is no external support,” he said, “and over time you end up with a handful of folks who understand them and are able to fully support them internally.”
He added that as yet another alternative, “We’ve been looking at PXI for a very long time because we’ve always believed that we would be able to develop a semicustom test system that is very focused on our needs but also is fully supported externally.” The debut of the STS, he said, “…sealed the deal for us. Because STS is based on the PXI platform, we know that as our devices become more complex we will be able to grow our tester and increase its performance”—while retaining IDT’s capital investment and engineering investment. With the PXI system, he said, “We can grow it rather than throw it away and start all over, which often is the case with big iron ATE systems.”
Jimenez said IDT already has three systems running in production, which have demonstrated the opportunity to reduce the cost of test.
Ed Paulsen, vice president of business development for semiconductor systems at Aeroflex, said that the company’s integrated subsystems incorporate multiple PXI or AXIe instruments into a chassis complete with a single subsystem-level driver and calibration. “These subsystems are ideal for augmenting existing production test systems and have been integrated onto nine existing ATE platforms to date,” he said. Subsystems can contain a mix of Aeroflex and third-party instruments and primarily are driven by customers looking to broaden the capability (for example, by adding RF functionality) and extend the useful life of existing production platforms, he added.
For complete turnkey systems, Paulsen said, Aeroflex can integrate a PXI or AXIe chassis or both into a small footprint test head complete with direct-mount device load boards, manipulator mounts, docking plates, and prober/handler control (Figure 2). The systems offer features such as multisite support, STDF data logging, and an operator interface. Turnkey systems also can contain a mix of Aeroflex and third-party instruments. “Complete systems,” he said, “are primarily driven by customers looking for a significantly differentiated, lower cost-of-test platform strategy for specific market segments.”
|Figure 2. AX1018 semiconductor test system |
Courtesy of Aeroflex
Aeroflex has several subsystems and systems that have been optimized for highly parallel efficient multisite production test, Paulsen said. The AXRF PXI subsystem supports eight to 32 universal RF ports operating at 50 MHz to 6 GHz CW. It can measure EVM/ACLR for all connectivity and cellular standards, S-parameters, and noise figure; it also can make CW two-tone and modulated two-tone measurements. The AX500 AXIe subsystem supports 12 to 48 DPS channels (±20 V at 1.2 A) and 48 to 192 digital channels. And AX Series systems are available in various turnkey configurations with multiple AX500 subsystems and/or AXRF subsystems augmented with select third-party PXI/AXIe instruments as required.
PXI for IC test
Mike Dewey, director of marketing at Marvin Test Solutions (MTS), commented, “For systems, we offer the TS-900, a PXI-based test system for digital and mixed-signal testing of ICs and SoCs (Figure 3). In terms of products, our line of PXI digital instrumentation is used for testing digital devices. The GX5295 provides 32 100-MHz channels with a PMU per pin, providing users with the ability to perform both functional and DC parametric test of devices. Additionally, the system can include one of our FPGA PXI cards, which can be synchronized with other system resources or used independent of other system instrumentation,” he explained.
|Figure 3. TS-900 semiconductor test system |
Courtesy of Marvin Test Solutions
Dewey said the card offers unique ATE test features that allow the user to configure and implement nonstandard interfaces as well as measurement and stimulus capabilities that are not common on standard ATE systems. The card also features a configurable plug-in daughter card that can provide additional flexibility for supporting specific signal-conditioning and analog-signal requirements. “This type of capability can significantly reduce the complexity and costs that would normally be part of a test system’s load-board design,” he said.
Modular semiconductor test systems find use in a variety of venues. “Aeroflex PXI and AXIe solutions are used throughout the complete semiconductor product life cycle and in many cases beyond semiconductor test and into module/final product test as well,” Paulsen said. “PXI and AXIe are pervasive in the lab and have proven advantages in terms of performance, flexibility, ease of use, and cost,” he said. “Improvements in execution times and scalability for PXI, and more importantly, its big brother AXIe, enable high-channel-count multisite solutions to be cost-effectively deployed in both wafer sort and final test production.” He added that using PXI and AXIe as a common, scalable platform from semiconductor design validation through production test and final product module or unit test provides significant time-to-market and time-to-yield benefits.
Dewey added, “We primarily see our products and systems being used in debug, verification, and failure analysis. However, we do have some customers using our products in production with moderate production volumes.” Types of measurements the MTS systems can make include DC parametric, functional test (analog and digital), analog parametric, time interval, and—if equipped—RF.
Semiconductor test software
Of course software plays a key role in semiconductor test, and Aeroflex, MTS, and NI all address the issue. The NI STS makes use of NI TestStand test-management software, and NI LabVIEW serves for code module development. Peer at IDT said the company for the first time has the opportunity to begin to bridge the gap between product engineering and the final test floor, using the same hardware all driven by LabVIEW.
Paulsen said Aeroflex employs a software programming model that supports integration with existing systems or use as a standalone system. In addition, the company offers a hardware and software infrastructure to support test-cell integration with probers and handlers.
“During the past year,” Dewey said, “we have spent significant effort developing software tools that simplify the development of semiconductor test programs.” This tool set, called ICEasy, simplifies the development and deployment of semiconductor tests such as measurement of input/output DC parameters and the generation of I-V curve plots and shmoo plots. “These are all tests that are used during the verification and early production of devices,” Dewey said. ”We also have expanded our tool set to include importing of digital test vectors—we currently support STIL, VCD, eVCD, and WGL formats.”
The system and the receiver interface are field-configurable, allowing users to upgrade and modify the test system for new applications. The configuration of the TS-900 can support up to 512 dynamic digital channels as well as a range of analog, power supply, and RF resources. Dewey concluded, “The open architecture of the system and its reconfiguration capability extend the product’s life-cycle investment. As test requirements evolve, new PXI instrumentation can be integrated into the system.”
Nelson, R., Instruments tackle IC test chores,” EE-Evaluation Engineering, July 2014, p. 12.