JP2008172274A - Method for controlling semiconductor inspection apparatus - Google Patents

Abstract

Provided is a control device for a semiconductor inspection apparatus capable of performing inspection without impairing reliability of measurement even when a power supply voltage fluctuates.
As a power source for a controller and a power-on circuit, a switching regulator designed to maintain an output voltage against a decrease in power supply voltage is used, and a means for detecting a decrease in power supply voltage is provided, and the power supply during measurement is provided. When a voltage drop is detected, the measurement is automatically stopped, and the remeasurement is automatically performed after the power supply voltage is restored.
[Selection] Figure 1

Description

  The present invention relates to a control apparatus for a semiconductor inspection apparatus using an electron beam length measuring apparatus and the like, and relates to control corresponding to a decrease in power supply voltage.

  In a semiconductor inspection apparatus such as an electron beam length measuring apparatus, the reliability of inspection results may be impaired by various disturbances such as mechanical vibrations and external magnetic fields. With respect to this problem, for example, as described in Japanese Patent No. 2911144 (Patent Document 1), a mechanical vibration or a means for detecting an external magnetic field, a mechanical vibration greater than a reference value, or A method has been proposed in which measurement is automatically stopped when an external magnetic field is detected.

  The problem that the reliability of test results may be impaired due to the above disturbance is not an exception even when the power supply voltage decreases. If the power supply voltage decreases during measurement, the reliability of the test results may be impaired. There is. However, when the power supply voltage is lowered, there is a problem that the reliability of the inspection result may be impaired, and the apparatus itself is stopped. Patent Document 1 does not mention this point.

  Further, in the past, an instantaneous voltage drop protection device 17 has been installed as shown in FIG. 4 to solve the problem that the device itself stops when the power supply voltage drops. When the instantaneous voltage drop protection device 17 is installed, when the power supply voltage drops for a short time, the power supply voltage supplied to the device does not drop and the device does not stop. Further, the reliability of the inspection result is not impaired. However, the installation of the instantaneous voltage drop protection device 17 increases the cost of the device, and the instantaneous voltage drop protection device 17 has a large footprint (installation area), resulting in control of the semiconductor inspection device. The device becomes large.

Japanese Patent No. 2911144

  In view of the above problems, the present invention is cheaper than that using an instantaneous voltage drop protection device, does not require a large installation location, and does not impair measurement reliability even if the power supply voltage fluctuates. An object of the present invention is to provide a control apparatus for a semiconductor inspection apparatus capable of performing the above.

  The present invention relates to a reduction in power supply voltage supplied to a DC constant pressure supply circuit that generates DC drive power supplied from an AC power supply to a measurement circuit that electrically processes measurement data of an object to be inspected, or return to a predetermined value. According to the above, the stop of the execution of the measurement of the inspection object is controlled.

  According to the present invention, by using a switching regulator, it is possible to provide a control apparatus for a semiconductor inspection apparatus that is inexpensive, does not require a large installation location, and can perform inspection without stopping even if the power supply voltage drops and fluctuates. .

  An example according to the embodiment of the present invention will be described with reference to FIGS.

  First, a block diagram of a control device for a semiconductor inspection apparatus will be described with reference to FIG. The control device includes a controller 1 and a measurement circuit 2. The measurement circuit 2 is a measurement circuit unit such as an electron beam length measuring device.

  The measurement circuit 2 receives a control signal from the controller 1 and electrically processes measurement data of the inspection object. The driving power of the controller 1 is supplied by the switching regulator 3 for the controller 1. The switching regulator 3 changes the alternating current of the power source to a constant pressure direct current and supplies it to the controller 1. The switching regulator 3 supplies a constant-pressure direct current to the controller 1 even if there is a voltage fluctuation in which the alternating power supply voltage drops. The switching regulator 3 is less expensive than the instantaneous voltage drop protection device. Further, since it is smaller than the instantaneous voltage drop protection device, as a result, a large installation location of the control device of the semiconductor inspection device is not required.

  The driving power for the measurement circuit 2 is supplied by the series regulator 4. The series regulator 4 supplies driving power in which the alternating current of the power source is changed to a constant direct current to the measurement circuit. The reason why the series regulator 4 is used as the power source of the measurement circuit 2 is to reduce noise applied to the measurement circuit 2.

  That is, the measuring circuit of the electron beam length measuring device is vulnerable to electrical noise generated from a chopping method such as a switching regulator, and causes measurement failure. Since the series regulator does not generate electrical noise, it is suitable for a measuring circuit of an electron beam length measuring device.

  If the measurement circuit other than the electron beam measuring device is not easily affected by electrical noise, it is not necessary to use a series regulator. However, a DC constant pressure supply circuit that supplies driving power to the measurement circuit is necessary. The DC constant pressure supply circuit includes a series regulator.

  The driving power of each of the switching regulator 3 and the series regulator 4 is supplied from the power source 8 via the power-on circuit 5 and the breaker 7. The driving power of the switching regulator 3 and the series regulator 4 is supplied or cut off by the operation of turning on / off the breaker 7.

  The power supply circuit 5 includes a contactor 9, an ON switch 15, and an OFF switch 16. The driving power for the power-on circuit 5 is supplied by a switching regulator 6 for the power-on circuit. The switching regulator 6 for the power-on circuit 5 has the same function as the switching regulator 3 for the controller 1 described above, and is less expensive than the instantaneous voltage drop protection device. Further, since it is smaller than the instantaneous voltage drop protection device, as a result, a large installation location of the control device of the semiconductor inspection device is not required.

  The switching regulator will be described in more detail.

  The switching regulators 3 and 6 are designed to maintain a constant DC output voltage against fluctuations in the power supply voltage.

  The switching regulator rectifies and smoothes the AC voltage, and then increases or decreases the voltage to generate a DC voltage. Even when the AC power supply voltage decreases, the output voltage can be maintained by increasing the switching pulse width or increasing the frequency. For example, in both the case where the power supply voltage is AC100V and AC200V, as described in page 87 of “Special issue on transistor technology SPECIAL No.28, latest power supply circuit design technology” (1991, issued by CQ Publishing Co., Ltd.) Like a wide input type switching regulator that can be continuously adapted, it can be designed to control the switching pulse width and frequency so as to maintain the output voltage against a wide input voltage change of AC90V to AC270V. Further, as described in JP-A-6-237579, it is possible to design to extend the output holding time by controlling the switching frequency at the time of an instantaneous power failure.

  In the switching regulators 3 and 6, for example, the input voltage range is AC85V to AC264V, and by using a wide input type switching regulator that can continuously cope with both the case where the power supply voltage is AC100V and AC200V, the power supply voltage The output voltage can be maintained even when the voltage drops to 85V, which is 42.5% of the rating.

  If the output voltages of the switching regulators 3 and 6 are maintained, the control device of the semiconductor inspection device can perform inspection without stopping.

  Next, the power supply voltage monitoring circuit will be described.

  If the output voltages of the switching regulator 3 for the controller and the switching regulator 6 for the power-on circuit are maintained as described above, the control of the semiconductor inspection apparatus is inspected without stopping. However, since the series regulator has a narrower allowable fluctuation range of the power supply voltage than the switching regulator, if the power supply voltage falls below the reference voltage, the supply of the constant-voltage DC drive power to the measurement circuit 2 becomes unstable and the measurement circuit 2 is affected. Measurement reliability may be impaired. A power supply voltage monitoring circuit is provided to cope with the problem that the reliability of the measurement is impaired.

  In other words, the output voltage of the series regulator 4 decreases in a short time when the power supply voltage decreases. The series regulator rectifies and smoothes the AC voltage, and then reduces the voltage to generate a DC voltage. When the power supply voltage falls below a certain voltage (reference voltage), the output voltage decreases as the power supply voltage decreases. Therefore, the output voltage decreases in a short time with respect to the decrease in power supply voltage.

  When the output voltage of the series regulator 4 decreases (the supply of constant-voltage direct current drive power becomes unstable), the entire control device of the semiconductor inspection device does not stop, but the measurement circuit 2 is affected and the measurement is performed. Reliability may be compromised.

  Therefore, when the power supply voltage of the power source 8 drops, the power supply voltage monitoring circuit 18 transmits a power supply voltage drop signal 19 to the controller 1. When the controller 1 detects a drop in the power supply voltage during the measurement, the measurement is automatically stopped, and after the power supply voltage returns to a predetermined value, the remeasurement is automatically performed by the power supply voltage return signal. If programmed, even if the reliability of the measurement is lost due to a drop in the power supply voltage, the measurement results are automatically re-measured after the power supply voltage is restored, ensuring the reliability of the final test results obtained. Is done. Further, as described above, since the switching regulators 3 and 6 maintain the output voltage even when the power supply voltage decreases, the controller 1 can operate normally, and the above processing can be executed reliably. Therefore, in the above configuration, the reliability of the test result obtained even when the power supply voltage is lowered is not impaired.

  Further, the DC constant pressure supply circuit for supplying the constant pressure DC driving power to the measurement circuit 2 is not limited to the series regulator. Even in the case of using a DC constant pressure supply circuit with a narrow allowable range of power supply voltage drop variation similar to that of the series regulator, by providing the power supply voltage monitoring circuit 18, the reliability of the test result obtained even when the power supply voltage is lowered can be obtained. There is no damage.

  That is, the power supply voltage monitoring circuit 18 monitors the power supply voltage, and when a drop in the power supply voltage is detected during the measurement, the measurement is automatically stopped, and the remeasurement is automatically performed after the power supply voltage is restored. As a result, it is possible to obtain the effect that the reliability of the obtained test result is not impaired regardless of whether or not the power supply of the measurement circuit 2 can maintain the output voltage against the decrease of the power supply voltage.

  FIG. 2 shows the configuration of the power supply voltage monitoring circuit.

  The power supply voltage monitoring circuit 18 includes a transformer 31, a rectifying / smoothing circuit 39, and a comparison circuit 40 with hysteresis.

  The power supply voltage 20 input to the power supply voltage monitoring circuit 18 is stepped down through a transformer 31 and rectified and smoothed by a rectifying / smoothing circuit 39. The output of the rectifying / smoothing circuit 39 is input to the comparator circuit 40 with hysteresis, and it is determined whether or not the voltage is equal to or higher than a certain voltage. When the voltage falls below the certain voltage, the power supply voltage drop signal 19 is output. Since the output of the rectifying / smoothing circuit 39 includes a ripple having a frequency twice as high as the frequency of the AC power supply, the comparator 40 with hysteresis must be a comparator with hysteresis having a hysteresis width wider than the width of the ripple. The threshold value (corresponding to the reference voltage) for determining the decrease in the power supply voltage in the comparator circuit 40 with hysteresis is set to a voltage that does not decrease the output voltage of the series regulator 4. When the power supply voltage is lowered and the output voltage of the series regulator 4 may be lowered by the power supply voltage monitoring circuit, the power supply voltage drop signal 19 is output.

  A flow of a control method based on the power supply voltage monitoring circuit will be described.

  FIG. 3 is a flowchart showing an embodiment of a control method when a drop in power supply voltage is detected according to the present invention. After the start of measurement in step 23, in parallel with the measurement process in step 43, it is determined whether or not the power supply voltage in step 41 is normal. The determination in step 41 is repeated until the measurement process is completed. If the power supply voltage is abnormal in step 41, the process proceeds to step 24 and the measurement is stopped. After stopping the measurement in step 24, the process proceeds to step 25 and waits until the power supply voltage is restored. When the power supply voltage is restored in step 25, the process proceeds to step 26, and remeasurement is started. After the start of remeasurement in step 26, the measurement process in step 43 and the determination of whether or not the power supply voltage in step 41 is normal are performed again in parallel. If an abnormality in the power supply voltage is detected again in step 41, the process proceeds to step 24 again and the above flow is repeated. If no power supply voltage abnormality is detected in step 41 during the measurement process, the process proceeds to step 27 and the measurement is terminated. According to the above control method, if the power supply voltage drops during measurement, the measurement is automatically stopped, and the remeasurement is automatically performed after the power supply voltage is restored, so the reliability of the obtained result is impaired. There is nothing.

The block diagram of the control apparatus of a semiconductor inspection apparatus which shows the Example concerning embodiment of this invention. The power supply voltage monitoring circuit which shows the Example concerning embodiment of this invention. FIG. 3 is a flowchart of a method for controlling a semiconductor inspection apparatus, showing an example according to an embodiment of the present invention. The block diagram which shows the case where the instantaneous voltage drop protection apparatus is installed in the conventional semiconductor inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Controller, 2 ... Measuring circuit, 3 ... Switching regulator, 4 ... Series regulator, 5 ... Power-on circuit, 6 ... Switching regulator, 7 ... Breaker, 9 ... Contactor, 17 ... Instantaneous voltage drop protective device, 18 ... Power supply voltage Monitoring circuit, 39... Rectification smoothing circuit,
40. Comparison circuit with hysteresis

Claims (1)

  In response to a decrease in power supply voltage supplied to a DC constant pressure supply circuit that generates DC drive power supplied from an AC power supply to a measurement circuit that electrically processes measurement data of an object to be inspected or to a predetermined value, A method for controlling a semiconductor inspection apparatus, comprising controlling execution stop of measurement of an inspection object.

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