Electronically resettable current protection for die testing

Electronically reset table test apparatus. The test apparatus includes an electronically operable current breaker connected to a test jig for testing semiconductor die. The electronically operable current breaker is connected through an interface that converts signals to signals appropriate for use on a computer bus to a computer system. The test apparatus can detect faults in the semiconductor die and open the electronically operable current breaker in response to detecting the fault. The electronically operable current breaker can be closed when the fault is removed.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The invention generally relates to the filed of component testing. More specifically, the invention relates to current protection used in test apparatuses for component testing.

2. Description of the Related Art

Manufacturing is an essential industry to provide products for all aspects of life. Manufacturing produces everything from large machinery to microscopic components such as those found in semiconductor chips. A part of the manufacturing process is quality control. Quality control helps to assure that manufactured components meet the expectations of consumers and the standards that a manufacturing facility sets for itself. High standards that translate to high quality components can set one manufacturer apart from other manufacturers. Quality control can include several components including inspection and testing.

Testing may include several components, including functional testing and burn in testing. Functional testing tests components to make sure that they perform within acceptable limits. Additionally, and especially in testing of devices like electrical devices, functional testing may be done to determine a device's ratings. Illustratively, one type of electrical device is the semiconductor laser. A semiconductor laser functions by producing coherent light in response to a current passed through the laser. Functional testing may be performed to determine how much current is needed for the laser to begin producing coherent light. Further, functional testing may also be used to determine how much coherent light is produced as a function of the current that is passed through the semiconductor laser. The semiconductor laser fails functional testing if it does not produce light or does not produce light at a sufficiently low current. Even if the semiconductor laser produces light at a sufficiently low current, the semiconductor laser has specific characteristics. Semiconductor lasers can be sorted into categories depending on their specific characteristics, which are discovered through functional testing.

Burn in testing tests devices for a period of time to make sure that the devices are not prone to failure. For example, a device may be connected to a power source and operated for a period of time. After the device has operated satisfactorily for a sufficient period of time, one can be reasonably assured that the device will not fail prematurely when finally installed in an end product.

Often, a device will contain flaws such that when connected for testing, the device causes a “short circuit” to the power source being used to test the device. In the example described above with a semiconductor laser, this may occur because of impurities in the semiconductor laser epitaxial structure or due to metal that has not been properly etched or for other reasons. These short circuits can causes fuses to blow or breakers to trip in the power source or in a source supplying the power source. Blown fuses and tripped breakers will halt testing at a test station until the fuse has been changed or the breaker reset. This clearly can cause inefficiencies in the testing process and can result in delays and increased costs.

BRIEF SUMMARY OF THE INVENTION

One embodiment described herein includes a test apparatus for testing a semiconductor die. The test apparatus includes a test jig configured to accommodate the semiconductor die. A power source is connected to the test jig. The power source is configured to supply current to the semiconductor die. A current sensor is connected to the test jig. The current sensor is configured to sense current passing through the semiconductor die. An electronically operable current breaker is connected to the test jig. The electronically operable current breaker configured to selectively complete and break a circuit that includes the power source. A computer is included in the test apparatus. The computer is configured to receive signals from the current sensor and to selectively cause the electronically operable circuit breaker to break the circuit including the power source in response to receiving signals from the current sensor indicating that a fault has occurred in the semiconductor die. The computer is further configured to selectively cause the electronically operable circuit breaker to complete the circuit that includes the power source in response to the fault being removed. The test apparatus further includes an interface connectable between the computer, the current sensor and the electronically operable current breaker. The interface allows the computer to connect to the current sensor and the electronically operable current breaker through a port on the computer.

Another embodiment includes an interface for use in testing semiconductor dies. The interface includes a power source for supplying current to a semiconductor die. A current sensor is connected to the power source. The current sensor is configured to sense current passing through the semiconductor die. An electronically operable current breaker is connected to the power source for selectively completing or breaking a circuit between the semiconductor die and the power source. Circuitry is connected to the current sensor. The circuitry connected to the current sensor is configured to convert signals from the current sensor to a form that is readable by a computer bus. Circuitry is connected to the electronically operable current breaker. The circuitry connected to the electronically operable current breaker is configured to receive signals from the computer bus and in response generate signals to selectively control the electronically operable current breaker to open or close a circuit including the power source and the semiconductor die.

These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments described herein relate to current protection apparatus to protect test equipment in the case of failure of a device during device testing. One embodiment includes for example a test jig that is designed to accommodate a semiconductor die. A power source is connected to the test jig. The power source is configured to supply current to the semiconductor die. A current sensor may be coupled to the test jig. The current sensor senses current passing through the semiconductor die. An electronically operable current breaker is connected to the test jig. The electronically operable current breaker can selectively complete and break a circuit that includes the power source. The computer may be configured to receive signals from the current sensor and to selectively, cause the electronically operable circuit breaker to break a circuit in response to receiving signals from the current sensor indicating that a fault has occurred in the semiconductor die. The computer may further be configured to complete a circuit that includes the power source once the fault is removed. An interface is included between the computer and the current sensor and electronically operable current breaker. The interface allows the computer to connect to the current sensor and electronically operable current breaker through a port on the computer.

Referring now toFIG. 1, a test topology example is illustrated where a semiconductor die102is placed in a test jig104for testing. The semiconductor die102may include for example, laser diodes, light emitting diodes (LED), photo diodes, or other types of semiconductor devices. The test jig104may include any one of a number of suitable test jig apparatus is.

FIG. 1also illustrates an electronically operable current breaker106connected to the test jig104. The electronically operable current breaker106includes a switching mechanism108that allows the electronically operable current breaker106to selectively complete and break a circuit that includes a power source that supplies power to the semiconductor die102through the test jig104. The electronically operable circuit breaker106may include for example a transistor such as the transistor shown inFIG. 2at202. Alternatively, the electronically operable current breaker106may include a silicon controlled relay (SCR), a mechanical relay, or other suitable current breaking means. The electronically operable current breaker106is connected to an interface110such that the interface110can provide signals to selectively open and close a circuit. The electronically operable circuit breaker106may be included as a separate component or as a part of the interface110. The interface110may include circuitry coupled to the current sensor. The circuitry coupled to the current sensor is configured to convert signals from the current sensor to a form that is readable by a computer bus. The interface110may further include circuitry coupled to the electronically operable current breaker. The circuitry coupled to the electronically operable current breaker is configured to receive signals from the computer bus and in response generate signals to selectively control the electronically operable current breaker to open or close a circuit including the power source and a semiconductor die.

The interface110may include various sub-components. For example as shown inFIG. 1, the interface110includes an interface board112and a computer interface114. The interface board112shown inFIG. 1includes a power source connected to the test jig104for supplying current to the semiconductor die102. The computer interface114provides in the example shown an interface between a port on a computer116and the interface board112. In one embodiment, the computer interface114may be for example the I2C/SPI Host Adapter. This particular device provides an interface between a USB port on the computer to an SPI interface. The interface board112may include in SPI interface for connecting to the computer interface114. The interface board112further includes logic for controlling various inputs and outputs such as for example he control line to the electronically operable current breaker106for completing and breaking the circuit supplying current to the semiconductor die102.

The embodiment illustrated inFIG. 1may also include a current sensor illustrated more fully inFIGS. 2A and 2B. In one embodiment the current sensor may include a resistor204. By measuring a voltage drop across the resistor204at terminals206the amount of current passing through the semiconductor die102can be calculated. In one embodiment, it may be desirable to physically position the resistor204such that it is in close proximity to the semiconductor die102. Typically, the current sense resistor204has a low Ohm value to limit the size of the voltage drop across to resistor204. This may require that the resistor204is of a higher Wattage.FIG. 2Billustrates an example where a toroid coil208may be used alternatively as a portion of the current sensor.

Referring once again toFIG. 1, a computer116may be connected to the interface110. In the example shown, the computer116is connected to the interface110through a computer interface114. As mentioned previously the computer interface114may be such that it is configured to connect to a computer port on the computer116. For example, the computer port on the computer116may include any one of an RS232 serial port, a USB port, a parallel port, an IEEE 1394 port, a wireless connection, a network connection, or any other appropriate port.

The computer116may be configured to perform various functions. For example the computer may be configured to receive signals from the current sensor through the interface110. The computer can then selectively cause the electronically operable circuit breaker106to break a circuit that includes a power source to supply the semiconductor die102in response to receiving signals from the current sensor indicating that a fault has occurred in the semiconductor die102. In addition, the computer116may be configured to complete a circuit that includes the power source to the semiconductor die102in response to a fault being removed at the test jig104. This allows the computer116to detect when a semiconductor die has failed indicated by a short circuit through the die and to automatically reset the electronically operable current breaker when a new semiconductor die102has been placed in the test jig104. The computer116may perform other functions including reporting functions for reporting short circuit failures and for tracking the results of any testing performed at the test jig104.