In accordance with some aspects, a method may be provided for detecting mechanical relay hot-switching events in a test system comprising a plurality of relays at corresponding relay locations. A detected hot-switching event may be correlated to a test system program instruction that triggered the hot-switching, such that the test system can be reprogrammed to avoid hot-switching and consequent damage. The inventors have recognized and appreciated that reliability of a test system may be increased by providing a mechanism to detect hot-switching. An instruction in the program, changing the state of a relay, may execute at a time when a voltage exists across the relay, for example when one or both of the relay contacts are connected to voltage source(s). Hot-switching may unintentionally occur in a test system as a result of the way a test program is written. During hot-switching, the contacts inside the relay touch as they are closing, which will generate a high amount of current and in turn, heat that can damage the contacts. However, mechanical relays are susceptible to damage as a result of a phenomenon known as “hot-switching.” Hot-switching occurs when a relay is opened or closed while a voltage exists across the contacts within the relay. Often, the relays are mechanical relays because such relays provide a very low on resistance as a result of metal contacts in the relay touching each other when the relay is closed. Tester 110 may be programmable such that execution of test system instructions, programmed into the tester 110 for performing specific tests on specific devices, control the state of the relays so that appropriate tester resources are connected to appropriate test points. To support these different test requirements, a test configuration 100 may include relays that may be opened or closed to selectively connect specific tester resources to test points on a device under test. Even during the test of a device under test, different types of test signals may be generated or measured at different times. Moreover, a tester 110 is programmable and can test different types of devices that require different types of test signals to be generated or measured to determine whether the device under test is operating properly. Thus, by changing the device interface, the same tester 110 may be used to test integrated circuits at different stages in their manufacture. But other device interfaces, including, for example, a probe card for making connections to a wafer for testing, may be used in other implementations.

For testing packaged devices, the device interface may be a device interface board 135, as illustrated in FIG. These differences enable the same tester 110 the ATE to be used for testing integrated circuit devices on a wafer prior to dicing the wafer or for testing the integrated circuits after they have been packaged. In some implementations, the device under test 150 may be a wafer while in other implementations the device under test may be one or more packaged integrated circuits. The nature of the device interface may depend on the specifics of the device under test. Each channel contact may be connected to a test point on a device under test 150 through a device interface. Within the tester, the tester resources are connected to channel contacts forming a tester interface 131. Tester 110 may include tester resources, sometimes called instruments, that generate or measure test signals. 1, a conventional test configuration 100 for semiconductor devices may include automated test equipment (sometimes referred to as a “tester” or an “ATE”).

The technology relates to methods and structures for calibrating test channels and reliability improvement of automated test equipment (ATE).

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