JP2007071822A - Apparatus and method of inspecting light receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect a light receiving device stably and safely at a low cost. <P>SOLUTION: The inspecting apparatus of the light receiving device comprises a connecting section (probe 4 or the like) electrically connecting to a terminal of the light receiving device 6A, a light source section 9 for radiating light to the light receiving device 6A, an acceleration sensor 22 for detecting vibration, weighting filters 23A and 23B for extracting a vibration component of a predetermined frequency from the output of the acceleration sensor 22, and an inspection section (LSI tester 1) that radiates light and can determine effectiveness of the light receiving signal level value output from the terminal of the light receiving device 6A when a bias is applied to the terminal of the light receiving device 6A based on the level value of the vibration component of the predetermined frequency. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light receiving device inspection apparatus having a configuration capable of determining the effectiveness of a measurement result at the time of inspection of the light receiving device and removing a measurement result having a large error due to vibration from the totalization, and an inspection method for the light receiving device.

  FIG. 11 shows a light receiving device inspection apparatus capable of inspecting a light receiving device in a bare chip state. Here, since the light receiving device is a semiconductor device, in order to improve inspection efficiency, it is common to inspect a semiconductor wafer in which a large number of light receiving devices are integrally formed.

In the illustrated light receiving device inspection apparatus, an XY stage 102 is provided in the main body 101 of the prober apparatus 100, and a number of light receiving devices 103A that are devices to be inspected (hereinafter referred to as “DUT (Device Under Test)”) are provided thereon. A semiconductor wafer 103 is placed.
Although not particularly illustrated, a probe card substrate equipped with a probe that electrically contacts the electrode pad of the light receiving device 103A, a wafer measurement board on which a measurement circuit electrically connected to a number of pins of the probe card substrate is formed, and a wafer A contact ring or the like for connecting the measurement board and the probe card substrate is also provided.

  The XY stage 102 is a high-precision mechanical means that performs an intermittent operation called “step and repeat” that moves each light receiving device (bare chip) of the semiconductor wafer 103 to the next bare chip at the end of the inspection. Etc. are also provided. An LSI tester (not shown) and the wafer measurement board are electrically connected via a cable and a connector as an interface.

On the main body 101 of the prober device 100, a light source unit 105 is provided supported by a light source holding unit 104.
The light source unit 105 includes a semiconductor laser 106, a collimator lens 107, and a focusing lens 108. The main body 101 of the prober apparatus is installed on the floor (ground) of a semiconductor manufacturing factory via a pedestal 109 for vibration reduction.

Here, since the light receiving surface of the light receiving device 103A is very small, the laser light emitted from the semiconductor laser 106 is converted into parallel light by the collimator lens 107, and then focused to a small spot by the focusing lens 108 and irradiated to the light receiving device 103A. It is like that.
However, the intensity of the laser beam spot focused by the lens increases only at the center thereof.

FIG. 12A shows a graph of the light intensity distribution of a laser spot with the distance in the X or Y direction on the horizontal axis and the light intensity on the vertical axis. 12B and 12C show the relationship between the laser spot LS and the light receiving surface DP of the light receiving device 103A.
Since the laser spot LS exhibits an intensity distribution as shown in FIG. 12A, the light received by the light receiving device 103A as shown in FIG. 12C when the inspection apparatus is vibrated for some reason or the like. There is a possibility that a deviation occurs at the center of the spot and the received light signal level is lowered.

The vibration that causes such a laser spot LS shift depends on the power characteristics of various motors and the like in the prober device 100 and the resonance characteristics including the main body 101, the light source holding unit 104, and the light source unit 105 of the prober device. However, each device has a unique frequency component.
Incidentally, the factor that affects the deviation of the laser spot LS is the movement accuracy of the stage 102, which is, for example, about 4 [μm], which is sufficiently smaller than the deviation amount of the laser spot LS due to vibration. For this reason, the stage movement accuracy can be ignored here.

  Even when such a laser spot LS shift occurs, it is not possible to quantify the degree of the shift and the deterioration of the light receiving characteristics caused thereby. For this reason, even if the light receiving device 103A has a non-standard light receiving characteristic, it is caused by a defect in the light receiving device 103A itself, caused by a deviation of the laser spot LS, or a combination of both. I can't judge. And in the light receiving device inspection sensitive to vibration, there arises a disadvantage that the inspection yield tends to decrease due to vibration.

As a solution, it is conceivable to attenuate the vibration itself as a solution to the above problem.
There is a method of installing a vibration isolation table between the inspection device and the ground instead of the base 109 shown in FIG. The vibration isolation table has an effect of eliminating vibration transmitted from the outside such as installation floor vibration as much as possible.

  On the other hand, the inspection apparatus is equipped with an XY stage 102 for moving the light receiving device 103A (bare chip) on the wafer, and the XY stage 102 is characterized by an intermittent operation called step & repeat, so that repeated step motion is excluded. Excites the vibration of the shaking table itself. Therefore, the vibration isolation table is required to achieve a good balance between the vibration isolation performance against external vibration and the vibration suppression performance against vibration generated by the operation of the internal equipment itself.

  In response to such demands, an anti-vibration table using a normal coil and damper makes it difficult to eliminate vibrations generated from the inside. Patent Document 1).

Further, a method is known in which the spot intensity distribution of the laser beam is made uniform so that the light intensity distribution at the measurement location does not change even if there is some vibration (for example, see Patent Document 1).
JP 2003-107124 A “Introduction to Vibration Engineering Supervised by Shinji Yamada Power Company”, p. 126

  However, when a vibration isolation table using a damper is provided as in Non-Patent Document 1, the apparatus becomes large and the cost increases.

In the method described in Patent Document 1, light emitted from a semiconductor laser is passed through a fly-eye lens to flatten the intensity distribution in the laser spot. The fly-eye lens is composed of a plurality of small lenses. Since the power of the laser beam is diffused by these plural lenses at the gathering, the light intensity level itself is lowered. For this reason, there is a disadvantage that the laser power incident on the light receiving surface of the light receiving device is low.
There is also a countermeasure to increase the output of the laser light source, but this increases the complexity of the laser control unit as the output increases, and also requires more advanced safety measures, increasing the overall size of the inspection device and increasing costs. .

  The problem to be solved by the present invention is to perform light-receiving device inspection stably and safely at low cost.

The light receiving device inspection apparatus according to the present invention includes a connection portion that electrically connects to a terminal of the light receiving device, a light source portion that irradiates light to the light receiving device, an acceleration sensor that detects vibration, and an output of the acceleration sensor A high-pass filter that extracts a vibration component of a predetermined frequency from, and the effectiveness of the received light signal level value output from the terminal of the light receiving device when the light is applied and a bias is applied to the terminal of the light receiving device, And an inspection unit that can be determined from the level value of the vibration component having a predetermined frequency.
In the present invention, it is preferable that the high-pass filter is a variable filter that can be adjusted to a predetermined pass frequency band corresponding to the natural vibration frequency of the inspection apparatus.
The present invention preferably includes a plurality of high-pass filters having different pass frequency bands, and further includes an adding unit that adds outputs of the plurality of high-pass filters.
In the present invention, preferably, a low-pass filter that extracts a low-frequency inclination change component from the output of the acceleration sensor, and the output of the low-pass filter is compared with a predetermined reference level, and the inclination is detected when the output exceeds the reference level. And an inclination comparison unit that outputs a detection signal, wherein the inspection unit can control the light source unit according to the input of the inclination detection signal and stop the light irradiating the optical device.

  Another light receiving device inspection apparatus according to the present invention includes a connection portion that electrically connects to a terminal of the light receiving device, a light source portion that emits light to the light receiving device, an acceleration sensor that detects vibration, and the acceleration sensor A high-pass filter that extracts a vibration component of a predetermined frequency from the output of the output, a vibration comparison unit that compares the output of the high-pass filter with a predetermined reference level and outputs a pulse each time the output exceeds the reference level, and the vibration comparison A counting unit that counts the number of pulses from the unit, an actual measurement period from when the light is irradiated and a bias is applied to the terminal of the light receiving device until a light reception signal level value is obtained from another terminal, An inspection unit capable of determining the validity of the received light signal level value based on the timing of the increase in the number of pulses counted by the counting unit.

The method for inspecting a light receiving device according to the present invention is a measurement step of electrically connecting a terminal of the light receiving device, irradiating light to the light receiving device, applying a bias, and obtaining a light reception signal level value from the terminal of the light receiving device. Detecting a vibration by an acceleration sensor, extracting a vibration component of a predetermined frequency from the output of the acceleration sensor, and determining the effectiveness of the received light signal level value from the level value of the vibration component of the predetermined frequency. Determining.
In the present invention, preferably, the method further includes a step of measuring in advance a natural vibration frequency when the apparatus used for the inspection is operated in the same manner as in the inspection, and in the step of extracting the vibration component of the predetermined frequency, The sensor output is filtered in a predetermined pass frequency band corresponding to the natural signal frequency.
In the present invention, preferably, in the step of extracting the vibration component having the predetermined frequency, a plurality of vibration components having different frequencies are extracted and added to determine the level of the vibration component having the predetermined frequency.
Preferably, the present invention further includes a step of extracting a low frequency inclination change component from the output of the acceleration sensor, and stops light irradiation to the light receiving device when the inclination change component exceeds a predetermined level. To do.

  In another inspection method for a light receiving device according to the present invention, electrical connection is made to a terminal of the light receiving device, light is applied to the light receiving device, a bias is applied, and a light reception signal level value is obtained from the terminal of the light receiving device. A step of measuring, a step of detecting vibration by an acceleration sensor, a step of extracting a vibration component of a predetermined frequency from the output of the acceleration sensor, comparing the level of the vibration component of the predetermined frequency with a predetermined threshold, A step of accumulating the number of levels exceeding the threshold value, an actual measurement period from when the bias is applied to when the received light signal level value is obtained, and a vibration component of the predetermined frequency being a predetermined threshold value And determining the validity of the obtained measurement value based on the increase timing of the integrated value obtained by integrating the number exceeding.

  According to the present invention, there is an advantage that a light receiving device inspection can be performed stably and safely at a low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, mainly using a light receiving device inspection apparatus that measures a light receiving device in a semiconductor wafer state as an example.

[First Embodiment]
FIG. 1 shows a schematic configuration of the light receiving device inspection apparatus according to the first embodiment.
This light receiving device inspection apparatus is for determining whether a light receiving device (for example, a photodiode or the like) has good DC characteristics, AC characteristics, and light receiving characteristics in a bare chip manufacturing process.
Among these, in the measurement of the light receiving characteristic, a laser beam or the like is irradiated and a bias is applied in a state where the light receiving device is electrically connected, and a measured value of the light receiving characteristic is obtained from the light receiving device. And the quality of the acquired measured value is compared with the preset reference level, and the quality is judged. At this time, for example, when the measured value level is equal to or higher than the reference level, it is determined to be a non-defective product, and when it is lower than the reference level, it is determined to be a defective product.

  The illustrated light receiving device inspection apparatus includes an LSI tester 1 and a prober apparatus 5. In the prober device 5, a wafer measurement board 2 on which a measurement circuit is formed and an XY stage 7 are provided. Usually, a probe card substrate (not shown) equipped with the probe 4 is pin-connected to the wafer measurement board 2. On the XY stage 7, a semiconductor wafer 6 on which a large number of light receiving devices 6A as device under test (DUT) are integrated is mounted.

The tip of the probe 4 extending from the wafer measurement board 2 side to the semiconductor wafer 6 is in contact with a terminal (electrode pad) (not shown) of the light receiving device 6A, and is electrically connected. The probe 4, a portion that holds the probe 4, and a cable or connector connected to the probe 4 correspond to the “connecting portion” of the present invention.
The LSI tester 1 and the wafer measurement board 2 are electrically connected via a cable 3a and a connector 3b as interfaces.

  The XY stage 7 is a high-precision mechanical means that performs an intermittent operation called “step and repeat” that moves each light receiving device 6A (bare chip) of the semiconductor wafer 6 to the next bare chip at the end of the inspection. Several motors and the like are provided for the drive. The XY stage 7 is normally capable of three-axis movement of the X axis, the Y axis, and the Z axis.

On the main body of the prober device 5, a light source unit 9 is provided supported by a light source holding unit 8.
The light source unit 9 includes a semiconductor laser 10 that is a light source, a collimator lens 11 that collimates the light output from the semiconductor laser 10, and a converging lens 12 that narrows the collimated light to an optimum spot diameter for inspection.

  The LSI tester 1 is a device that controls the driving of the light source unit 9 and the prober device 5, supplies a bias via the cable 3a, and further determines whether the product is good or defective from the measured values obtained from the cable 3a. . Usually, according to a program stored in a built-in computer-based control unit, control of each unit, bias supply, non-defective product determination, and the like are performed. Note that “inspection” refers to a series of processes including all control and determination necessary for measurement in addition to actual measurement.

  The main body of the LSI tester 1 and the prober device 5 is installed on the floor (ground) of a semiconductor manufacturing factory via pedestals 1A and 5A, respectively, for vibration reduction.

  In the present embodiment, a vibration measuring device 20 is provided on the light source unit 9. As will be described later, the vibration measuring device 20 includes an acceleration sensor and a processing circuit for its output. The vibration measuring device 20 includes a cable 21 for supplying the processed output to the LSI tester 1, and the tip of the cable 21 is connected to the connector 3b.

FIG. 2 shows electrical circuit elements of the light receiving device inspection apparatus in the inspection state.
In the LSI tester 1, a voltage source 41 that applies a reset pulse S 41 to the vibration measuring device 20 at an arbitrary timing and a constant current source 43 that supplies a driving current to the semiconductor laser 10 are provided.
The constant current source 43 is used for any of DC measurement, AC measurement, and light receiving characteristic measurement. Note that an AC signal source for AC measurement and a configuration for superimposing the AC signal on the supply line of the constant current source 43 are not shown.

The LSI tester 1 is equipped with voltage sources 44 and 45 for supplying a bias to the light receiving device 6A and voltmeters 42 and 46 for measuring DC levels. Note that the AC level measurement voltmeter is not shown.
The voltage values of the constant current source 41 and the voltage sources 41, 44 and 45 can be arbitrarily set within the specification range of the LSI tester 1.

  The wafer measurement board 2 shown in FIG. 2 mainly shows only probe connection wiring of a probe card substrate (prober), and other measurement circuits and wiring thereof are omitted. In FIG. 2, the vibration measuring device 20, the light source unit 9, and the light receiving device 6 </ b> A are drawn surrounded by broken lines, but these are provided separately from the wafer measurement board 2 (see FIG. 1) for convenience. , Shown in the wafer measurement board 2.

The voltage source 44 supplies a high-level power supply voltage Vcc, and the voltage source 45 supplies a low-level power supply voltage Vee. Their outputs are connected to the probe 4 via a cable 3a, a connector 3b and an internal wiring 31, respectively. ing.
Similarly, the other probes 4 are connected to the ground potential in the LSI tester 1.
These probes 4 are in contact with electrode pads (not shown) of the light receiving device 6A and are electrically connected.

The light receiving device 6A incorporates a photodiode 70 in which a current proportional to the power level of incident light flows and a current-voltage conversion circuit 71 that converts the current into an appropriate voltage for one channel.
The output of the current-voltage conversion circuit 71 and the ground potential electrode pad (not shown) are connected to the voltmeter 46 in the LSI tester 1 via the probe 4, the internal wiring 32, the connector 3b, and the cable 3a.
Light incident on the photodiode 70 is supplied from the semiconductor laser 10 in the light source unit 9. The anode of the semiconductor laser 10 is connected to a constant current source 43 in the LSI tester 1 via an internal wiring 33, a connector 3b, and a cable 3a.

  The vibration measuring device 20 includes an acceleration sensor 22, two weighting filters 23 </ b> A and 23 </ b> B, an addition circuit 24, a sensitivity adjustment circuit 25, and a peak hold circuit 26.

The acceleration sensor 22 is a device that detects the vibration of the inspection apparatus, particularly the prober apparatus 5, and converts the mechanical vibration into an electrical signal.
As the acceleration sensor, a sensor using a piezoresistive effect, a sensor using MEMS (Micro Electronics Mechanical System), or the like can be used.
Moreover, the acceleration sensor can generally measure both static acceleration (static) used for tilt angle measurement and dynamic acceleration (dynamic) used for vibration or impact measurement. A representative example of static acceleration is earth gravity.

The weighting filters 23A and 23B are circuits for limiting the band of the output of the acceleration sensor 22 and extracting a vibration component having a specific frequency.
The pass band is set by a filter coefficient, and the pass band is different between the weighting filters 23A and 23B.

The prober device 5 has a unique vibration frequency depending on its structure, the casing, the rigidity of various parts, and the like. When the internal natural vibration frequency and the external vibration frequency substantially coincide with each other, it resonates and becomes a large vibration.
In addition, it is usually designed so that there is no mechanically moving part at the time of measurement, but there may be a case where the XY stage 7 is slightly vibrated due to some influence such as a resonance aftermath. .

In FIG. 2, two weighting filters 23A and 23B are provided.
However, the number is arbitrary, and the number of weighting filters may be one or three or more. In other words, depending on the inspection device and the environment in which it is placed, such as vibration caused by internal vibration, external vibration, or resonance, there are multiple frequency bands of vibration that have a significant impact on the laser spot during measurement. If there are, it is advisable to provide as many weighting filters as there are.

  The adder circuit 24 is a circuit for adding the outputs from the weighting filters 23A and 23B, and can be omitted when the number of weighting filters is one.

FIG. 3 shows a case where there is one weighting filter 23.
In FIG. 2, the weighting filters 23 </ b> A and 23 </ b> B are connected in parallel between the acceleration sensor 22 and the addition circuit 24.
On the other hand, in FIG. 3, one weighting filter 23 is connected between the acceleration sensor 22 and the adding circuit 24.

  The sensitivity adjustment circuit 25 is a circuit that amplifies the output level of the addition circuit 53 and adjusts the output sensitivity of the acceleration sensor 22. When the output level of the acceleration sensor 22 is large and sensitivity adjustment is not necessary, the sensitivity adjustment circuit 25 can be omitted.

The peak hold circuit 26 is a circuit that holds the peak value of the output signal of the sensitivity adjustment circuit 25.
The peak value held by the peak hold circuit 26 is input to the voltmeter 42 for DC level measurement in the LSI tester 1 and measured.
The peak hold circuit 26 has a reset input terminal for setting the held peak value to approximately 0 [V]. The reset pulse S41 is generated by the voltage source 41 in the LSI tester 1 and supplied to the reset input terminal. The peak hold circuit 26 performs peak holding at the low level of the reset pulse and reset operation at the high level.
There are various circuit configurations for the peak hold circuit. For example, a circuit using an operational amplifier and a diode can be employed.

  FIG. 4 is a flowchart showing the procedure of the light receiving device inspection. Hereinafter, the inspection method will be described with reference to FIG. 4, and FIGS.

First, initial setting / adjustment is performed in step ST0.
The purpose of this process is to optimize the frequency characteristics (passband) of the weighting filters 23A and 23B and the sensitivity characteristic of the sensitivity adjustment circuit 25 in the vibration measuring device 20 shown in FIG.

In the optimization of the pass band, first, the natural vibration frequency of the prober device 5 is obtained.
In the example of FIG. 1, the vibration measuring device 20 including the acceleration sensor 22 is provided on the light source unit 9. However, the natural vibration frequency measurement point is preferably as close as possible to the inspection point, that is, the vicinity of the tip of the probe 4. . Therefore, it is preferable to place only the vibration measuring device 20 or the acceleration sensor 22 at a location near the inspection point in the prober device 5. For example, the acceleration sensor 22 may be attached to the XY stage 7 and other circuits in the vibration measuring device 20 may be included in the circuit of the wafer measurement board 2.

  There are various methods for measuring the natural vibration frequency. For example, the natural vibration frequency of the inspection apparatus is obtained using a resonance method or an impulse vibration method. Note that the natural vibration frequency is not limited to one.

Next, the frequency characteristics of the weighting filters 23A and 23B (or 23) are adjusted.
The frequency characteristics of the weighting filters 23A and 23B (or 23) are matched with the evaluation result of the natural vibration frequency of the inspection apparatus, the signal in the band near the natural vibration frequency is more emphasized, and the signal in the other band is suppressed. To.

In the adjustment of the sensitivity characteristic of the sensitivity adjustment circuit 25, the light receiving device 6A is irradiated with laser light from the light source unit 9 (FIG. 1), and the light reception signal level of the measurement value from the light receiving device 6A is measured.
Next, vibration is gradually applied to the inspection device, and the voltage level of the vibration measuring device when the received light signal level value changes (decreases) can be accurately and stably measured with the voltmeter for measuring the DC level of the LSI tester 1. Then, the gain of the sensitivity adjustment circuit 25 is adjusted. As a criterion for determining whether or not the received light signal level value has changed, for example, the fact that the level value is decreased by 1 [%] when there is no vibration is used. The output voltage value of the vibration measuring device at that time is stored as “threshold voltage S1”.
Thus, the optimization of the circuit of the vibration measuring device 20 is completed.

  Next, in step ST1 of FIG. 4, the XY stage 7 is moved, and the electrodes of the probe 4 and the light receiving device 6A are aligned and electrically contacted.

  In step ST2, upon receiving a start signal from the wafer measurement board (or prober) 2, a test program is executed by the LSI tester 1, and a DC test (open / short “O / S” test, Conduct current and terminal “electrode” voltage tests).

  In step ST3, a drive current is applied to the semiconductor laser 10 via the LSI tester 1, the optical power is set to a predetermined value, and the light receiving device 6A is irradiated with light.

  In step ST4, the variable n indicating the actual number of measurement repetitions is set to an initial value “1”, and the variable x indicating the final number of repetitions is set to a predetermined value.

In step ST5, the reset pulse S41 is input to the vibration measuring device 20 via the LSI tester 1, and the output voltage is once reduced to zero.

In step ST6, the light receiving signal level value of the light receiving device 6A and the output voltage (vibration detection result) of the peak hold circuit 26 in the vibration measuring device 20 are measured by the LSI tester 1. At this time, it is desirable to perform the measurement of the received light signal level and the vibration detection almost simultaneously. If it cannot be performed simultaneously, the light reception signal level of the light receiving device 6A is measured first.
The output voltage of the peak hold circuit 26 obtained here is assumed to be “V”.

In step ST7, the output voltage value V of the vibration measuring device 20 is compared with the value of the threshold voltage S1 obtained earlier.
When the output voltage value V is larger, the light reception signal level of the light receiving device 6A is subjected to external vibration during measurement. Alternatively, the inspection apparatus is vibrated by the movement of the XY stage, and is thus affected by the remaining vibration that is not attenuated. Therefore, in these cases, it is assumed that the light reception signal level may have changed (decreased). Therefore, it is confirmed that the variable n has not reached the variable x indicating the final time (step ST9), the number of variables n is incremented (step ST10), and then the process returns to step 5 to repeat the same steps.

In the middle of this repetition, if it is determined that the influence of the vibration is x times continuously, the determination in step ST9 is “Yes”, and it is considered that some trouble has occurred in the inspection apparatus, and in step ST11. The inspection is forcibly terminated by displaying a warning “vibration” or the like.
Then, take measures by checking the equipment or checking the environment.

  If the threshold voltage S1 is greater than the output voltage value V in step ST7, it is determined that there is no vibration and does not affect the inspection, and the next test is performed in step ST8. Alternatively, when all the test items for the light receiving device 6A are completed, the XY stage is moved to move to the next light receiving device 6A.

Through the above steps, in the inspection process of irradiating light to the light receiving device 6A, if vibration is applied to the inspection apparatus, the yield is improved by performing remedial treatment by re-inspection, and low-cost and stable inspection is performed. It can be carried out.
Also, if the number of repetitions of re-inspection is set, and if the number of repetitions is greater than or equal to the number of repetitions, it is considered that some trouble has occurred in the inspection device, and it is forcibly terminated and at the same time a warning is given to the operator and the device is inspected. Maintenance can be stabilized and production efficiency can be improved.

[Second Embodiment]
FIG. 5A shows a schematic configuration of the prober device of the second embodiment.
In the second embodiment, the light shielding cover 13 is attached around the light emitting portion of the light source unit 9. Further, the hinge 14 is connected to the light source holding unit so that the light source holding unit 8 and the light source unit 9 can be opened (tilted) with respect to the prober device 5 during adjustment, maintenance, and the like of the probe 4 and the wafer measurement board 2. 8 and the prober device 5.
The light shielding cover 13 is attached as a safety measure for preventing light from the semiconductor laser 10 from leaking to the outside. Further, the measurement accuracy can be improved by shielding light from the outside by the light shielding cover 13.

Here, during the execution of the test program, the operator may inadvertently raise the light source unit 9 while the semiconductor laser 10 is irradiated in order to visually confirm the probe 4, the wafer measurement board 2, and the like. At this time, as shown in FIG. 5B, the light may be directed to the worker side due to reflection or the like.
In order to prevent this, the light emission of the semiconductor laser 10 can be stopped by detecting that the light shielding cover 13 and the prober device 5 are separated by a contact switch or the like. However, a mechanical switch such as a contact switch may not be able to stop light emission due to a contact failure.

Therefore, in the second embodiment, tilt detection is performed using the static acceleration measurement function of the acceleration sensor 22. Specifically, when the light irradiation unit is tilted up, the vibration measuring device 20 provided on the inspection device is also tilted, and the tilt is detected.
In response to the result, the drive current to the semiconductor laser 10 in the light source unit 9 is forcibly stopped to turn off the light irradiation.
In the present embodiment, it is necessary to provide the vibration measuring device 20 in the light source unit 9. When it is desired to detect vibration near the inspection point of the light receiving device 6A, at least two acceleration sensors 22 are prepared, and one is installed near the inspection point and the other is installed above the light source unit 9 or the like.

FIG. 6 shows electrical circuit elements of the light receiving device inspection apparatus in the inspection state of the second embodiment.
As a change from the first embodiment, a low-pass filter 27 and a voltage comparison circuit (comparator) 28 are newly added in the vibration measuring device 20.
In addition, a relay 15 is newly added in the light source unit 9. The control power supply for the relay 15 is supplied from an arbitrary power supply voltage (here, Vdd), and the control voltage is supplied from the output of the comparator 28. The relay 15 is turned off when the output of the comparator 28 is at a high level, and the relay 15 is turned on when the output is at a low level.
Since other than that is the same as that of 1st Embodiment, description is abbreviate | omitted.

Next, the operation in the second embodiment will be described focusing on the added part.
As shown in FIG. 5B, when the light source unit 9 is lifted, the vibration measuring device 20 is tilted. Therefore, the output (DC) voltage value of the acceleration sensor 22 increases substantially in proportion to the tilt angle. The output (DC) voltage is noise-removed to suppress malfunction by the low-pass filter 27 and is sent to the non-inverting input terminal “+” of the comparator 28.

  Here, the reference voltage on the inverting input “−” side that determines the threshold voltage of the comparator 28 is supplied from the voltage source 48 via the LSI tester 1. The voltage value of the voltage source 48 can be arbitrarily set within the specification range of the LSI tester 1. The comparator 28 is preferably a circuit with a hysteresis function in order to avoid malfunction when the input voltage is in the vicinity of the comparison threshold.

  When the output voltage of the low-pass filter 27 exceeds the threshold voltage optimized in advance, the output of the comparator 28 immediately changes from the low level to the high level, and in response to this, the relay 15 in the light source unit 9 turns from on to off. . Therefore, the drive current to the semiconductor laser 10 is forcibly stopped, and the light irradiation is turned off.

Here, the acceleration detection direction (axis) of the acceleration sensor will be described.
In general, an acceleration sensor has detection directionality and the number of detection directions (axis) so that it can detect 1 axis (X), 2 axes (X, Y), and 3 axes (X, Y, Z) according to its specifications. It has become. In the first embodiment, basically only one axis (X) is required, but in the second embodiment, the detection direction is restricted because the inclination is detected.

7A and 7B show directions in which the inclination can be detected.
When the vibration detection direction and the inclination detection direction are different, it may be desirable to use a biaxial acceleration sensor as shown in the figure.

  According to the second embodiment, in the inspection process of irradiating light to the light receiving device 6A, not only the yield reduction due to vibration is improved, but also when the light source unit 9 is inclined for adjustment and maintenance, the inclination Detect the angle. And if the inclination of the light source part 9 is detected, the light irradiation of the semiconductor laser 10 can be stopped immediately, and the inspection apparatus desirable for safety can be provided.

[Third Embodiment]
As a change from the first embodiment, the present invention is applied to the assembly inspection.

FIG. 8 shows a schematic configuration of the prober device of the third embodiment.
Hereinafter, the third embodiment will be described with reference to this figure. However, since the configuration of the vibration measuring device 20 and a specific test method example are the same as those in the first and second embodiments, the description of the part will not be given. Omitted.
FIG. 8 schematically shows only the portion related to the changed portion. The LSI tester 1, the handler, the test head, the light receiving device 6A shown in FIG. 1, the contact probe that is electrically connected to the inspection jig, and mechanical. A socket, a housing and the like to be fixed to are not shown.

As shown in FIG. 8, the light receiving device 6A of the assembly which is a DUT is accommodated in a package 6B, and a socket (on the assembly inspection jig 60 provided in place of the wafer measurement board 2 (FIG. 1). (Not shown).
Similar to the wafer measurement board 2, the assembly inspection jig 60 is provided with a measurement circuit and a connector 3b connected to the cable 21 and the LSI tester 1 (FIG. 1).

[Fourth Embodiment]
FIG. 9 shows electrical circuit elements of the light receiving device inspection apparatus in the inspection state.
As changes from the first embodiment, in the vibration measuring device 20, a voltage comparison circuit (comparator) 50 connected to the output of the sensitivity adjustment circuit 25, a counter 51 connected to the output of the comparator 50, A digital-to-analog converter (DAC) 52 connected to the output of each carry of the counter 51. Other than that, the description is omitted because it is the same as FIG.

The comparator 50 is a circuit in which the output voltage of the sensitivity adjustment circuit 25 is connected to the non-inverting input terminal “+”, and the voltage is compared with the threshold voltage input to the inverting input terminal “−”.
The threshold voltage is supplied from the voltage source 47 via the LSI tester 1. The voltage value of the voltage source 47 can be arbitrarily set within the specification range of the LSI tester 1. The comparator 50 corresponds to the “vibration comparison unit” of the present invention.

  The counter 51 is a 6-bit binary counter circuit that counts up with the output rising pulse of the comparator 50 and further has a reset function. The reset pulse S42 is sent from the LSI tester 1 and is reset at a high level.

The DAC 52 is a 6-bit DAC circuit, and an arbitrary circuit such as an ADC circuit using a ladder-type resistor array composed of two resistance values (R and 2R) can be used. The DAC 52 inputs each output of the counter 51, and the output voltage is configured to have a voltage value corresponding to the count number of the DAC 52. Therefore, the DAC output indicates an integrated value of the number of times that the vibration detection level exceeds the threshold value.
The counter 51 and the DAC 52 constitute pulse counting means, which correspond to the “counter” of the present invention.

For example, if 1LSB of the counter 51 is 32 [mV] and the minimum voltage is 0 [V], the maximum voltage value is
32 [mV] x (64-1)
= 2016 [mV]
It becomes.

After reset, if the number of pulses of the counter 51 is “5”, the output voltage value of the DAC 52 is
32 [mV] x (5-1)
= 128 [mV]
It becomes.

  Note that the number of bits of the counter circuit and the DAC circuit may be optimized as necessary.

  The reason for providing the counter 51 and the DAC 52 is to make it easy to capture the number of output pulses of the comparator 50 during the test period into the LSI tester 1. By measuring the output voltage of the DAC 52 and converting the voltage into a count number, the count number can be obtained in a batch.

When the pulse tester is built in the LSI tester, it is not necessary to provide the counter 51 and the DAC 52 in the vibration measuring device 20. However, when a low-cost tester is used, since such a means is generally not built in, it is necessary to provide the counter 51 and the DAC 52 on the vibration measuring device 20 side. In any case, the light receiving device inspection apparatus has pulse counting means.
Further, the pulse count means can be realized by a memory or the like. However, when the memory is used, signal line control for data processing becomes complicated.

Next, an example of a method for inspecting a light receiving device will be described.
First, as a preliminary preparation, the threshold voltage of the comparator 50 is set in the internal circuit of the vibration measuring device 20.

The light receiving device 6A is irradiated with laser light, and the light receiving signal level value from the light receiving device 6A is measured.
Next, vibration is gradually and strongly applied to the inspection device (prober device 5), and the output voltage value of the sensitivity adjustment circuit 25 when the received light signal level value changes (decreases) is monitored. As a criterion for determining whether or not the received light signal level value has changed, for example, the fact that the level value is decreased by 1 [%] when there is no vibration is used. Then, the voltage source 47 in the LSI tester 1 is set to the same voltage as the output voltage value of the sensitivity adjustment circuit 25 monitored (measured), and the voltage value is set as a threshold voltage to be used thereafter.
Thus, the optimization of the circuit of the vibration measuring device 20 is completed.

Next, a specific test method will be described. Here, FIG. 10 is used.
FIG. 10 is a diagram summarizing the test flow and signal flow in time series. 10A shows an output (vibration) voltage waveform of the sensitivity adjustment circuit 25, FIG. 10B shows a test sequence performed on the light receiving device 6A, and FIG. 10C shows a reset pulse S41 to the counter 51. 10D shows the output pulse waveform of the comparator 50, FIG. 10E shows the output voltage waveform of the DAC 52, FIG. 10F shows the measurement capture timing of the vibration detection result, and FIG. G) shows the capture timing of the received light signal level value of the light receiving device 6A.

First, the XY stage 7 (see FIG. 1) is moved, and the electrodes of the probe 4 and the light receiving device 6A are aligned.
At this time, as the XY stage moves, the inspection apparatus is vibrated and vibrates vigorously. Further, even after the movement of the XY stage 7 is finished, the vibration continues for a certain period while being attenuated.

After the alignment is completed, a test program is executed by the LSI tester 1. First, as shown in FIG. 10B, a DC test (open / short “O / S” test, current consumption) that is an electrical test without light irradiation. , Test terminal "electrode" voltage, etc.).
At this time, when the vibration is attenuated in advance, the reset pulse S41 is input to the counter 51 via the LSI tester 1, set to the reset state, and the output voltage value of the DAC 52 is temporarily set to the initial voltage (here, 0 [V]).

  Here, the XY stage 7 is an intermittent operation called step & repeat, and moves the light receiving device 6A every time measurement is completed. However, the movement amounts of the X axis and the Y axis are not always the same. For example, a case where the light receiving device 6 </ b> A is at the end of the semiconductor wafer 6 can be cited. Therefore, the duration of vibration starting from the end of the movement of the XY stage 7 slightly changes for each measurement.

In order to confirm that the vibration has subsided in the reset state, the output voltage value of the DAC 52 is measured, and the vibration detection result is obtained.
This timing is indicated by “T1” in FIGS. 10E and 10F. If the output voltage value of the DAC 52 is not 0 [V], it is considered that the vibration still remains. Therefore, the reset pulse S41 is input again, and it is confirmed that the output voltage value of the DAC 52 becomes the initial voltage. On the other hand, the timing of the reset pulse S41 may be delayed in view of the margin.

After the DC test is completed, “light irradiation test 1” is executed as shown in FIG.
A drive current is applied to the semiconductor laser 10 via the LSI tester 1, the optical power is set to a predetermined value, and the light receiving device 6A is irradiated with light.
Next, before measuring the received light signal level of the light receiving device 6A, first, in order to obtain the vibration detection result, the output voltage value of the DAC 52 is measured and stored. This timing is indicated by “T2” in FIGS. 10E and 10F.

  Next, the light receiving signal level of the light receiving device 6A and the output voltage value of the DAC 52 are again measured almost simultaneously. When simultaneous measurement cannot be performed, the light reception signal level of the light receiving device 6A is measured first. This timing is indicated by “T3” in FIGS. 10E and 10F.

Here, the output voltage value of the DAC 52 obtained at the capturing timing of “T2” and “T3” is compared, and if they are the same, it can be considered that the vibration that adversely affects the light reception signal level of the light receiving device 6A has not occurred.
If they are not the same, that is, if the voltage value has increased, it is assumed that the received light signal level may have changed (decreased) due to the influence of vibration. Therefore, in this case, the step of measuring the light receiving signal level of the light receiving device 6A and the output voltage value of the DAC 52 almost simultaneously is repeated again. In this case, as in the first embodiment, the number of repeated steps is limited as necessary.

After the light irradiation test 1 is completed, the light irradiation test 2 is executed as shown in FIG.
The drive current applied to the semiconductor laser 10 is changed, the optical power is set to a predetermined value, and the light receiving device 6A is irradiated with light.
Next, the light receiving signal level of the light receiving device 6A and the output voltage value of the DAC 52 are measured almost simultaneously. This timing is indicated by “T4” in FIGS. 10E and 10F. If necessary, the output voltage value of the DAC 52 may be measured before the light receiving signal level of the light receiving device 6A.

  Here, the output voltage value of the DAC 52 obtained at the capturing timing of “T3” and “T4” is compared. In FIG. 10, it is assumed that vibration has occurred, and the results are not the same. Therefore, it is assumed that the light reception signal level may have changed (decreased) due to the influence of vibration. Therefore, the step of measuring the light reception signal level of the light receiving device 6A and the output voltage value of the DAC 52 almost simultaneously is repeated again. This timing is indicated by “T5” in FIGS. 10E and 10F.

Since the output voltage value of the DAC 52 obtained at the timing of “T5” is the last, in the case of FIG. 10, it can be confirmed that there was a vibration that adversely affects the light reception signal level of the light receiving device 6A three times during the test period. . This result is added and recorded as one of the test items of the light receiving device 6A.
Here, in this example, the light irradiation test is performed twice, but the number of tests can be changed depending on the specification of the light receiving device 6A to be inspected.

According to the fourth embodiment, it is possible to perform quantitative evaluation by detecting vibration that has an adverse effect on the inspection apparatus and measuring the frequency of occurrence of vibration during the test period with a simple circuit configuration.
Therefore, when installing inspection equipment (equipment) in a semiconductor manufacturing factory, it can be used as a material for determining whether the ground vibration state and inspection equipment state are appropriate. It is also suitable for maintenance of equipment when moving.
In general, the same devices are installed on a large (floor) floor for manufacturing and inspection of semiconductor manufacturing factories. Naturally, the strength of the (floor) floor varies depending on the installation location, and the amount of vibration given to the inspection equipment is also affected by the amount of traffic of the operator, the airflow status of the air conditioner, and the presence of a large device nearby. The impact will change. Therefore, by using the fourth embodiment, quantitative evaluation can be performed, and it can be determined whether the installation location is appropriate.

According to the above first to fourth embodiments, the following benefits can be obtained.
First, in the inspection process in which the light receiving device 6A is irradiated with light, vibrations are picked up by an acceleration sensor. If vibrations are applied to the inspection device, a remedial treatment by re-inspection is performed, thereby reducing the yield. Improved, low-cost and stable inspection can be performed.

  Second, adding and optimizing a weighting filter circuit to the vibration measuring device, emphasizing frequency components that directly (badly) affect the inspection result of the inspection device due to vibration, and suppressing other frequency components such as noise Thus, the inspection can be performed with high accuracy.

  Third, set the number of re-inspection repetitions, and if the number exceeds the number of repetitions, it is considered that some trouble has occurred in the equipment system. It is possible to improve the production efficiency.

  Fourth, when the light irradiation part on the prober is inclined for adjustment, maintenance, etc., the inclination angle can be detected and the light irradiation of the semiconductor laser can be stopped immediately, which is safe.

  Fifth, the present invention can be applied to, for example, a semiconductor laser inspection process in addition to the inspection process of the light receiving device 6A. Further, the present invention can be applied to an assembly inspection process.

  Sixth, by using the fourth form in particular, it is possible to detect vibrations that have an adverse effect on the inspection equipment, and to measure and quantitatively evaluate the frequency of vibration occurrence during the test period with a simple circuit configuration. When installing the inspection equipment (equipment), it can be used as a basis for determining whether the ground vibration and inspection equipment are in proper condition, reducing the measurement time by reducing the number of repeated measurements, and moving the equipment It is also suitable for maintenance.

1 is a schematic configuration diagram of a light receiving device inspection apparatus according to a first embodiment. It is a figure which shows the electrical circuit element of the light-receiving device test | inspection apparatus in a test | inspection state. It is a block diagram of a vibration measuring device with one weighting filter. It is a flowchart which shows the procedure of a light reception device test | inspection. It is the structure schematic of the prober apparatus of 2nd Embodiment, and shows the case where the steady state and the light source part are inclined. It is a figure which shows the electrical circuit element of the light-receiving device test | inspection apparatus in a test | inspection state. It is the side view and top view of an inspection apparatus which show the direction which can detect inclination. It is the structure schematic of the prober apparatus of 3rd Embodiment. It is a figure which shows the electrical circuit element of the light-receiving device test | inspection apparatus in a test | inspection state. It is the figure which put together the flow of a test, and the flow of a signal in time series. It is a general block diagram of a light receiving device inspection apparatus. It is a figure which shows the light intensity distribution of a laser spot, and the positional relationship with respect to the light-receiving surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... LSI tester, 2 ... Wafer measurement board, 5 ... Prober apparatus, 6 ... Semiconductor wafer, 6A ... Light receiving device, 7 ... XY stage, 8 ... Light source holding part, 9 ... Light source part, 10 ... Semiconductor laser, 13 ... Light shielding Cover, 14 ... Hinge, 15 ... Relay, 20 ... Vibration measuring device, 22 ... Acceleration sensor, 23, 23A, 23B ... Weighting filter, 24 ... Adder circuit, 25 ... Sensitivity adjustment circuit, 26 ... Peak hold circuit, 27 ... Low pass Filter, 28, 50 ... Comparator, 51 ... Counter, 52 ... DAC, 60 ... Inspection jig for assembly

Claims (10)

A connecting portion for making an electrical connection to a terminal of the light receiving device;
A light source unit that emits light to the light receiving device;
An acceleration sensor that detects vibration;
A high-pass filter that extracts a vibration component of a predetermined frequency from the output of the acceleration sensor;
Inspection that can determine the effectiveness of the light reception signal level value output from the terminal of the light receiving device when the light is applied and a bias is applied to the terminal of the light receiving device from the level value of the vibration component of the predetermined frequency And
A light receiving device inspection apparatus. The light-receiving device inspection apparatus according to claim 1, wherein the high-pass filter is a variable filter that can be adjusted to a predetermined pass frequency band according to a natural vibration frequency of the inspection apparatus. A plurality of the high-pass filters having different pass frequency bands;
The light receiving device inspection apparatus according to claim 1, further comprising an adding unit that adds outputs of the plurality of high-pass filters. A low-pass filter for extracting a low-frequency slope change component from the output of the acceleration sensor;
A slope comparison unit that compares the output of the low-pass filter with a predetermined reference level and outputs a slope detection signal when the output exceeds the reference level;
Further comprising
The light receiving device inspection apparatus according to claim 1, wherein the inspection unit is capable of stopping the light applied to the optical device by controlling the light source unit according to an input of the tilt detection signal. A connecting portion for making an electrical connection to a terminal of the light receiving device;
A light source unit that emits light to the light receiving device;
An acceleration sensor that detects vibration;
A high-pass filter that extracts a vibration component of a predetermined frequency from the output of the acceleration sensor;
A vibration comparison unit that compares the output of the high-pass filter with a predetermined reference level and outputs a pulse each time the output exceeds the reference level;
A counting unit for counting the number of pulses from the vibration comparison unit;
The actual measurement period from when the light is applied and a bias is applied to the terminal of the light receiving device until the light receiving signal level value is obtained from the other terminal, and the increase in the number of pulses counted by the counting unit An inspection unit capable of determining the validity of the received light signal level value based on the timing;
A light receiving device inspection apparatus. A measurement step of making an electrical connection to a terminal of the light receiving device, irradiating the light receiving device with light, applying a bias, and obtaining a light receiving signal level value from the terminal of the light receiving device;
Detecting vibration with an acceleration sensor;
Extracting a vibration component of a predetermined frequency from the output of the acceleration sensor;
Determining the effectiveness of the received light signal level value from the level value of the vibration component of the predetermined frequency;
A method for inspecting a light-receiving device having A step of measuring in advance the natural vibration frequency when the device used for the inspection is operated in the same manner as in the inspection,
The light receiving device inspection method according to claim 6, wherein in the step of extracting the vibration component of the predetermined frequency, the sensor output is filtered in a predetermined pass frequency band corresponding to the natural signal frequency measured in advance. The light receiving device inspection method according to claim 6, wherein in the vibration component extraction step of the predetermined frequency, a plurality of vibration components having different frequencies are extracted and added to determine a level of the vibration component of the predetermined frequency. Extracting a low-frequency slope change component from the output of the acceleration sensor,
The light receiving device inspection method according to claim 6, wherein when the tilt change component exceeds a predetermined level, the light irradiation to the light receiving device is stopped. A measurement step of making an electrical connection to a terminal of the light receiving device, irradiating the light receiving device with light, applying a bias, and obtaining a light receiving signal level value from the terminal of the light receiving device;
Detecting vibration with an acceleration sensor;
Extracting a vibration component of a predetermined frequency from the output of the acceleration sensor;
Comparing the level of the vibration component of the predetermined frequency with a predetermined threshold, and integrating the number of the level exceeding the threshold;
Based on the actual measurement period from when the bias is applied to when the received light signal level value is obtained, and the increase timing of the integrated value obtained by integrating the number of vibration components of the predetermined frequency exceeding a predetermined threshold Determining the validity of the obtained measurement value;
A method for inspecting a light-receiving device having

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