JP2007335651A - Apparatus and tool for measuring optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively measure characteristics of a device under test relatively accurately. <P>SOLUTION: There are provided a measuring tool 50 and a measuring section (various members for terminal connection, circuits or the like). The measuring tool 50 comprises a light emitting element 151 for emitting light with which the device under test (DUT10) is irradiated; a reflecting member 154 partly opened; and a light receiving device (monitor PD22) for receiving monitoring light emitted from the light emitting element 151 and passing through an opening 154A in the reflecting member 154, and generating an output in response to the amount of the received light. The measuring section implements measurement of characteristics of the DUT10, and at least one of correction of a measured result based on an output of the monitor PD22 and of power supply and control to the DUT10 at the time of the measurement. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical device measuring apparatus and an optical device measuring jig for measuring characteristics of a device to be inspected such as a light receiving device by irradiating light.

The light receiving device needs to guarantee optical characteristics (light receiving characteristics) when irradiated with predetermined light in the form of the final product after assembly.
However, the electrical characteristics (consumption current, dark current, etc.) of the light-receiving device in the semiconductor wafer state are measured with a semiconductor wafer inspection device, the quality of the electrical characteristics alone is judged, and the light-receiving characteristics ( When measuring output DC voltage, incident optical power, etc.), what is determined as non-defective in the electrical characteristics may be determined as defective in the light-receiving characteristics.
Assembling such a defective device is disadvantageous in terms of cost because it results in loss of parts and man-hours, and this is because the improvement point cannot be clarified unless it is measured after assembly at the time of trial production in the development stage. Is a factor that lengthens the development period.

  An apparatus that irradiates light to a light receiving device in a semiconductor wafer state and measures the light receiving characteristics is known (see, for example, Patent Document 1).

As shown in FIG. 1, a device measuring apparatus described in Patent Document 1 uses a fiber optic 82 to transmit light to a light receiving surface of one light receiving device 83A of a semiconductor wafer 83 placed on a stage 81 for holding the wafer. , And a metal contact needle (probe) 84 is brought into contact with the electrode of the light receiving device 83A to measure the light receiving characteristics.
Japanese Patent Publication No. 1-17251

Since the device measuring apparatus described in Patent Document 1 uses the optical fiber 82, a part of the optical power may be outside the optical fiber 82 depending on the angle at which the fiber is bent and the laser wavelength. In this case, since the refractive index in the optical fiber 82 changes depending on the laser wavelength, an optical loss (loss of optical power) occurs, and the light receiving sensitivity characteristic for measuring the output level of the element by entering the optical power is measured accurately. Can not.
In addition, since extraneous light is not blocked, measured values such as dark current are likely to change depending on the environment of the place of use.

  The problem to be solved by the present invention is to realize measurement of optical characteristics (light receiving characteristics) of a light receiving device or a device to be inspected having a light receiving section with relatively high accuracy and low cost.

An optical device measuring apparatus according to the present invention includes a light emitting element that emits light to be irradiated to a device to be inspected, a reflective member that is provided on the opposite side of the light emitting element from the device to be inspected, and that is partially open, and the light emitting element A measuring jig on which a light receiving device that receives monitor light passing through the opening of the reflecting member and generates an output corresponding to the amount of received light is fixed, and the characteristics of the device under test are measured. And a measurement unit that performs at least one of calibrating the measurement result based on the output from the light receiving device and controlling the power supply to the device to be inspected at the time of the measurement.
In the present invention, it is preferable that the measurement unit includes a high frequency superimposing circuit that superimposes an AC signal on a driving current supplied to the light emitting element, and a tester that measures the characteristic by changing the frequency of the AC signal.
In the present invention, preferably, the measurement jig includes a light shielding cover that covers the light emitting element, the reflecting member, and the light receiving device, and is moved to the light emitting element in conjunction with the removal of the light shielding cover from the measurement jig. The current supply can be stopped.
More preferably, a connector of a cable for supplying a current to the light emitting element is provided on a substrate of the measuring jig to which the light shielding cover is fixed, and the connector also serves as a fixing means for the light shielding cover. .

  An optical device measuring jig according to the present invention includes a light emitting element that emits light to irradiate a device to be inspected, a reflective member that is provided on the opposite side of the light emitting element from the device to be inspected, and that has a part open, and the light emission A light receiving device that receives monitor light output from the element and passes through the opening of the reflecting member and generates an output corresponding to the amount of received monitor light is fixed to the base substrate.

According to the present invention, the light emitting device is provided as a light source for irradiating the device under test (optical device) with light, and the reflecting member is provided on the side opposite to the device under test. Since the reflecting member reflects light from the light emitting device, the light efficiently enters the device to be inspected.
A part of the reflecting member is opened, and a light receiving device is provided correspondingly. The light receiving device is used for monitoring light, and the measurement unit can monitor the amount of light incident on the device under test of the light emitting device by the light from the light receiving device. At this time, the output of the light receiving device is used for calibration of the measurement result and input power control to the device to be inspected.
In this case, it is possible to irradiate the device to be inspected and monitor the amount of light with a single light source, but at that time, it is not necessary to bend the light in a direction other than toward the inspection target.

  According to the present invention, there is an advantage that measurement of optical characteristics (light receiving characteristics) of a device to be inspected can be realized with relatively high accuracy and low cost. Further, the apparatus can be reduced in size.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 2 shows a schematic configuration of an optical device measuring apparatus that measures a light receiving device in a semiconductor wafer state.
The illustrated optical device measurement apparatus includes an LSI tester 1 and a prober apparatus 5. A probe card board 4 equipped with a probe, a wafer measurement board 2 in which a measurement circuit electrically connected to a number of pins of the probe card board 4 is formed in the prober device 5, the wafer measurement board 2 and the probe card board 4 is provided with a contact ring 8 for connecting to a stage 4 and a stage 7 for holding a wafer. A semiconductor wafer 6 having a device to be inspected (hereinafter referred to as “DUT (Device Under Test)”) is placed on the stage 7. The LSI tester 1 and the wafer measurement board 2 are electrically connected via a cable 3a and a connector 3b as interfaces.

FIG. 3 shows an assembly diagram of the wafer measurement board 2 and the probe card substrate 4.
The wafer measurement board 2 and the probe card substrate 4 are electrically connected to a plurality of sockets (not shown) formed on the contact ring 8 by pins 4A, and the fixing is performed by screws 4B. The reason why the probe card substrate 4 is not integrated with the wafer measurement board 2 is that the probe card substrate 4 needs to be replaced in consideration of the lifetime of the probe.
Note that various electrical components such as a relay, a capacitor, and a resistor are mounted on the wafer measurement board 2 as components constituting a measurement circuit for measuring the DUT. The card edge 2B at the tip of the wafer measurement board 2 is a portion that is inserted into the connector 3b (see FIG. 1) in order to be electrically connected to the LSI tester 1.

FIG. 4 is a cross-sectional view showing a portion around the probe card substrate 4 of the optical device measuring apparatus. One pellet of the semiconductor wafer 6 is the DUT 10, and FIG. 4 shows a state in which the probe of the probe card substrate 4 is in contact with the DUT 10.
In FIG. 4, the probe card substrate 4 includes a probe 11 that is in contact with an electrode pad (not shown) of the DUT 10, a probe holder 12 that holds the probe 11 and fixes the probe 11 to the probe card substrate 4. Is provided. In FIG. 4, the wafer measurement board 2 shown in FIGS. 2 and 3 and the contact ring 8 for electrically connecting the wafer measurement board 2 and the probe card substrate 4 with a large number of pins 4A are not shown. is doing.

On the opposite side of the surface of the probe card substrate 4 to which the probe 11 is fixed, an auxiliary substrate 13 serving as a base of a measurement jig 50 described later is provided. The auxiliary board 13 is positioned with respect to a predetermined position of the probe card board 4 by positioning pins 14a and 14b. In practice, the contact ring 8 and the wafer measurement board 2 are interposed between the probe card substrate 4 and the auxiliary substrate 13.
The auxiliary substrate 13 and the probe card substrate 4 fixed via the contact ring 8 and the wafer measurement board 2 are fixed by screws or the like which are omitted in FIG. That is, first, as shown in FIG. 3 and already described, the probe card substrate 4 is fixed to the contact ring 8 fixed to the wafer measurement board 2 with screws. Next, the auxiliary substrate 13 is fixed to the wafer measurement board 2 with another screw (not shown). For this reason, both the auxiliary substrate 13 and the probe card substrate 4 are removable from the wafer measurement board 2.

A measurement jig 50 is fixed on the probe card substrate 4.
The measurement jig 50 is for holding an LED 15 as a light source of the DUT 10 and a light receiving device for monitoring the optical power of the LED 15, for example, a photodetector (hereinafter referred to as “monitor PD”) 22. The measuring jig 50 is assembled by fixing many members to the auxiliary substrate 13.
Although details will be described later, the measuring jig 50 can be attached to and detached from the probe card substrate 4 and the like, thereby enabling the light receiving device measurement function to be added to a general probe card.

FIG. 5 shows a reflective LED 15 suitable for the present embodiment.
The reflective LED has a structure that can receive most of the light emitted from the light emitting element once at the reflective surface behind it and then radiate the light to the outside after being reflected by the reflective surface. It is an LED that can obtain high external radiation efficiency.
In this embodiment, it is desirable to use a reflective LED 15 having a reflective surface, but it is also possible to use a combination of a bullet-type LED and a reflective member. Since the bullet-type LED emits only the light radiated from the light-emitting element to the outside, only the light directly reaching the resin lens in front is emitted to the outside. So efficiency is bad. However, it is possible to increase the amount of monitor light by providing an LED structure that can radiate part of the light from the light emitting element also to the side and rear, and providing a reflective member there.

  Specifically, the reflective LED 15 shown in FIG. 5 includes a light-emitting element 151 via a conductive adhesive on the surface of one of the leads 152a and 152b that supplies power to the internal light-emitting element 151. Is mounted, and the other lead 152a and the light emitting element 2 are bonded by a wire 153 for electrical connection. In addition, the LED 15 is attached with a concave reflecting member 154 formed by, for example, pressing an aluminum plate so as to substantially cover one side of the light emitting element 151 in a hemispherical shape. The light emitting element 151, the leads 152a and 152b, the wire 153, and the reflecting member 154 are sealed with a transparent epoxy resin 155. At the same time, a part of the transparent epoxy resin 155 has a flat plate shape on the back side of the light emitting element 151 (the side opposite to the side on which the reflecting member 154 is attached), thereby forming the radiation member 156.

The LED 15 may have any specifications (structure, shape, material, etc.) without departing from the spirit of the present invention.
An opening 154A is formed in the reflecting member 154 incorporated in the reflective LED 15 shown in FIG. The opening 154A is for emitting a part of the light from the light emitting element 151 to the outside as monitor light, and has a position and a size that can fulfill its role. For example, an opening 154A is formed almost directly above the light emitting element 151 mounted on the lead 152b. The same applies to the case of a bullet-type LED, and it is necessary to form an opening that plays the same role in a reflecting member fixed to the LED.
The number of openings 154A may be plural in accordance with the number of light receiving devices (monitor PD22), the number of light receiving portions, and the positional relationship. However, in the present embodiment, since the light receiving part of the monitor PD 22 is single, one opening 154A is also formed.

As shown in FIG. 4, the LED 15 is fixed around the opening 13 </ b> A of the auxiliary substrate 13 with the radiation member 156 positioned at the opening. In practice, the LED 15 is fixed to the auxiliary substrate 13 via a housing (not shown).
Further, the lead 152a is electrically connected to the one power supply wiring (not shown) formed on the auxiliary substrate 13 by the wire 24a, and the lead 152b is connected to the other power supply wiring (not shown) by the wire 24b. Electrically connected. However, this also shows an electrical connection relationship, and in actuality, electrical connection is performed via a connection lead or the like of a housing (not shown).
Here, the auxiliary substrate 13 also has a light shielding function so that light emitted from the LED 15 does not enter the monitor PD 22 due to wraparound from other than the opening 154A.

Around the mounting position of the LED 15, a standing part 20 standing from the auxiliary board 13 is provided, and a PD wiring board 23 holding a monitor PD 22 as a light receiving device is fixed to the standing part 20.
The monitor PD 22 is obtained by packaging a light receiving device of the same type as the DUT 10 in a wafer state with a transparent resin (or glass), and is mounted on the lower surface of the PD wiring board 23 in order to monitor the optical power of the LED 15. . The PD wiring board 23 has an internal wiring (not shown) connected to the terminal of the monitor PD 22, and a cable 24 c is drawn from the internal wiring, and this is connected to the auxiliary board 13 via a connector (not shown). Yes.

The monitor PD 22 monitors the power of the light transmitted from the LED 15 through the opening 154A, so that the light receiving surface of the light receiving unit 22A has a transmission window to obtain a certain degree of tolerance in the positional accuracy of the light receiving unit 22A. It is desirable that it is wide enough for the size.
Specifically, if the opening 154A is too small, the light power passing therethrough is small, and therefore the monitor output voltage is small and the measurement accuracy may be lowered. Further, if the opening 154A is too large, the optical power applied to the DUT 10 is undesirably reduced. Therefore, the size of the opening 154A is the total optical power emitted from the light emitting element 151 by the light power passing through the opening 154A. It is good to set it to about 1/10 to 1/5.

Here, since the total radiated light power is received once by the concave reflecting surface and then reflected, assuming that the in-plane distribution intensity of the power does not change with respect to the radiation (light power) level of the LED 15, The relative ratio of the optical power corresponding to the area of the opening 154A to the optical power is constant.
Therefore, the optical power irradiated to the DUT can be calculated by measuring the output of the light receiving device for monitoring.

A component indicated by reference numeral “29” is mounted on the mounting surface of the PD wiring board 23. The component 29 includes a current-voltage conversion circuit for generating a voltage output since the monitor PD 22 is a current output.
A component indicated by a symbol “R2” is mounted on the mounting surface of the auxiliary substrate 13. This component R2 is a component (resistance) for impedance matching.

The LED 15 and the monitor PD 22 arranged in this way and the wafer measurement board 2 (not shown) are connected by cables 25 and 31. The DUT 10 is electrically connected to the wafer measurement board 2 by the cable 32 via the probe 11 or the like.
In this example, SMA (Subminiature A) connectors are used as connectors for these cables. More specifically, the SMA male side connectors 26 and 27 are mounted on the auxiliary substrate 13, and the SMA male side connector 41 is mounted on the probe card substrate 4. Then, the coaxial cable 25 is connected to the connector 26, the coaxial cable 31 is connected to the connector 27, the coaxial cable 32 is connected to the connector 41, and the connectors 25A, 31A, and 32A on the SMA female side provided at one end of each cable. ing. Similarly, the other ends (not shown) of the coaxial cables 25, 31, and 32 are connected to the wafer measurement board 2 (not shown) by SMA connector pairs.
Among these, the coaxial cable 25 is a line for supplying a current for driving the LED 15. The coaxial cable 31 is a line for the output of the monitor PD 22. The coaxial cable 32 is a line for outputting the DUT 10.

  A power supply cable 28 for supplying a power supply voltage Vcc, a reference voltage Vee, and a ground voltage GND is further drawn from the auxiliary board 13. A connector (male side) 28 </ b> A is provided at the tip of the power supply cable 28. The wafer measurement board 2 may be provided with a connector (female side) so that the power supply cable 28 can be detached from the auxiliary substrate 13.

FIG. 6 shows a top view of the light shielding cover 30 and FIG. 7 shows an assembly view of the light shielding cover 30.
As shown in FIG. 6, a flange portion flange portion 30 </ b> A that protrudes outward with respect to the side surface is provided at the open surface (lower surface) end portion of the light shielding cover 30. Ear portions 40a and 40b are provided at two locations opposed to the flange portion 30A. The ears 40a and 40b are each provided with a circular hole for passing an SMA connector (male side).

  As shown in FIG. 7, the ears 40a and 40b are passed through the SMA male-side connectors 26 and 27 corresponding to the coaxial cables 25 and 31, respectively, and from there, the SMA female-side connectors of the coaxial cables 25 and 31 are connected. Tightened with 25A and 31A. Thereby, the light shielding cover 30 and the coaxial cables 25 and 31 can be simultaneously fixed to the auxiliary substrate 13.

The coaxial cables 25 and 31 can be detached from the auxiliary board 13 by turning the connectors 25A and 31A on the SMA female side provided at the ends of the coaxial cables 25 and 31 in the opposite direction to the tightening. As a result, fixing (crimping) of the light shielding cover 30 is released, and the light shielding cover 30 can be removed from the auxiliary substrate 13.
Due to the mounting structure of the light shielding cover 30, when the light shielding cover 30 is removed, the coaxial cable 25 is always separated from the auxiliary substrate 13, so that the drive current does not flow to the LED 15 and light emission stops. For this reason, when the light shielding cover 30 is removed, the light emission of the LED 15 stops, which is preferable for safety.

In the present embodiment, an attachment structure for simultaneous attachment / detachment of the light shielding cover 30 and the coaxial cable 25 is desirable, but is not essential. In this case, for safety reasons, it is preferable to take measures to stop the light emission of the LED when the light shielding cover 30 is removed.
Further, various coaxial cables 25, 31, 32 are used for connection between the auxiliary substrate 13 and the wafer measurement board 2 (not shown), and a connector is also used for the power supply cable 28, but this is not essential. For example, the connection between the auxiliary substrate 13 and the wafer measurement board 2 may be realized by a connector and a pin that connect the two.

FIG. 8 shows an electrical circuit diagram of the optical device measuring apparatus in the inspection state.
In the LSI tester 1, a constant current source 51, an AC signal source 52 and its equivalent output resistance R1 (for example, 50 ohms), an output relay switch S1, voltage sources 53, 54, 55, 56, and AC / DC level measurement Voltmeters (AC / DC voltmeters) 57 and 58 are provided. The voltage values of the constant current source 51 and the voltage sources 53, 54, 55, and 56, and the frequency and output amplitude level of the AC signal source 52 can be arbitrarily set within the specification range of the LSI tester 1.

  A probe card substrate 4 connected to the wafer measurement board 2 is equipped with a measurement jig 50 and a probe 11. The probe 11 is in contact with an electrode pad (not shown) of the DUT 10.

The DUT 10 in this example includes a photodiode 70 through 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 the number of channels (in this example, one channel). Built-in.
The number of channels of the circuit block comprising the photodiode 70 and its current-voltage conversion circuit 71 is one channel here, but if a LED with a relatively wide light emission angle (wide directivity) is used, a plurality of channels are used. It can also be used with built-in light receiving devices. In addition, measurement can be performed with the configuration of the photodiode 70 alone, in which case the current-voltage conversion circuit 71 is omitted.

The current-voltage conversion circuit 71 in this example includes a differential amplifier 72 and a feedback resistor R3. A photodiode 70 is connected between the inverting input “−” of the differential amplifier 72 and the ground voltage, and a feedback resistor R3 is connected between the inverting input “−” of the differential amplifier 72 and the output. The power supply voltage Vcc and the reference voltage Vee are supplied to the differential amplifier 72, and the non-inverting input “+” is grounded.
The output of the differential amplifier 72 is taken out from the probe 11 to the outside of the DUT 10 and further connected to the AC / DC voltmeter 57 of the LSI tester 1 via coaxial cables 32 and 62. The power supply voltage Vcc and the reference voltage Vee are supplied from the variable voltage sources 55 and 56 in the LSI tester 1 via the probe 11, respectively. The incident light power to the photodiode 70 is applied from the LED 15 in the measurement jig 50.

In the measurement jig 50, an LED 15 for supplying optical power and a resistor R2 for impedance matching are incorporated. Note that the switch indicated by the reference sign “S2” in FIG. 8 is such that when the light shielding cover 30 of the measurement jig 50 is removed (see FIG. 5), the coaxial cable 25 supplying the drive current is separated from the jig and the drive current. This action is expressed by an equivalent switch since the supply of light stops and the light emission stops.
The equivalent switch S2, the resistor R2, and the LED 15 are connected in cascade between the connector pair 26, 25A of the coaxial cable 25 and the ground voltage.

Since the monitor PD 22 uses the same type as the DUT 10 here, the monitor PD 22 has the same circuit configuration as the DUT 10 and includes a photodiode 70, a differential amplifier 72, and a feedback resistor R 3.
The output of the differential amplifier 72 is connected to the voltmeter 58 for measuring the AC / DC level of the LSI tester 1 through the connector pairs 27 and 31A and the coaxial cables 31 and 63. The power supply voltage Vcc and the reference voltage Vee are supplied from the variable voltage sources 53 and 54 in the LSI tester 1 through the power supply cable 28, the connector 28A, and the cable 64.

A high frequency superimposing circuit 61 is connected to the coaxial cable 25 for supplying power to the LEDs in the wafer measurement board 2. The high frequency superimposing circuit 61 is a circuit that superimposes an AC signal on a constant current for LED driving from the LSI tester 1.
A constant current source 51 is connected between the DC input of the high frequency superimposing circuit 61 and the supply line of the source voltage Vdd in the LSI tester 1. An output relay switch S1, an equivalent output resistor R1, and an AC signal source 52 are connected between the AC input of the high-frequency superimposing circuit 61 and a ground voltage supply line in the LSI tester 1.

  FIG. 9 shows a line configuration of the DC input node Na, AC input node Nb, and output node Nc of the high-frequency superimposing circuit 61. As a cable connected to all these nodes, a coaxial cable in which the periphery of the signal line is shielded with a ground voltage line is used.

FIG. 10 shows a circuit example of the high frequency superimposing circuit 61.
The high frequency superimposing circuit 61 includes a capacitor C1 for removing noise, a coupling capacitor C2 for cutting DC, and a choke coil L1. Choke coil L1 is connected between DC input node Na and output node Nc, capacitor C1 is connected between DC input node Na and ground voltage, and coupling capacitor C2 is connected to AC input node Nb and output node Nc. Connected between.

  When the output relay switch S1 is off, a constant current from the constant current source 51 in the LSI tester 1 is supplied from the DC input node Na into the high frequency superimposing circuit 61, passes through the choke coil L1, and directly from the output node Nc. Is output. In this DC operation, since the impedance (DC resistance) of the choke coil L1 is substantially zero, the constant current for the LED drive current from the LSI tester 1 remains as it is (that is, with almost no loss). It passes through the coil L1 and is supplied to the LED 15.

  When the output relay switch S1 is turned on, the AC signal is supplied from the AC signal source 52 in the LSI tester 1 to the AC input node Nb through the equivalent output resistor R1 and the output relay switch S1 in the on state. The AC signal is superimposed on the constant current supplied from the DC input node Na via the coupling capacitor C2. In this AC operation, the impedance of the choke coil L1 becomes almost infinite. Therefore, assuming that the operating voltage value of the LED 15 is constant, the AC signal (AC current) from the AC signal source 52 is equivalent to the equivalent output resistance R1 and It flows through the resistor R2 and the LED 15 to the ground voltage line. Therefore, the AC current superimposed at a high frequency is a value obtained by dividing the amplitude of the AC signal source 52 by the sum of the resistance values of the equivalent output resistance R1 and the resistance R2. That is, the superimposed level of the AC current is determined according to these resistance values and the amplitude of the AC signal. The resistor R2 is for impedance matching and is provided to match the impedance of the LED drive current line with the impedance of the coaxial cable 25.

A specific test method using the optical device measuring apparatus configured as described above will be described mainly with reference to FIG.
As a pre-preparation before mounting the monitor PD 22 on the measuring jig 50, the reference optical power is inputted to the monitor PD 22 in advance, and the DC output data of the monitor PD 22 is changed while changing the optical power level at a plurality of levels as required. Repeat measurement. From this measurement result, the DC light receiving sensitivity characteristic of the monitor PD 22, that is, the relationship between the output DC voltage and the incident light power is obtained and recorded for calibration.
Similarly, the reference optical power superimposed with the high frequency is irradiated, and the AC output data is repeatedly measured while changing the frequency at a plurality of values as necessary, and the AC light receiving sensitivity characteristic of the monitor PD 22 is similarly measured. Find this and record it for calibration.

Next, a reference wafer having a chip that has been evaluated in advance by another means and has been calibrated is set, and the chip is used as a DUT.
A drive current is passed through the LED 15 to irradiate the light receiving surface of the DUT with light. Then, the drive current is adjusted while measuring the DC output voltage (measured value of the voltmeter 57) of the DUT so that the light power applied to the light receiving surface becomes a certain power level (for example, 100 [μW]). To do. More specifically, the absolute amount of light power incident on the light receiving surface can be known from the output of the monitor PD 22 from the DC light receiving sensitivity characteristic of the monitor PD 22 previously obtained above. The drive current is adjusted so that an output that achieves a power level is obtained.
When the power level reaches a predetermined level, the output voltage of the monitoring light receiving device 22 is measured via the AC / DC voltmeter 58. This is recorded as calibration data.
If necessary, the optical power is changed at several points and recorded as calibration data in the same manner.

Next, light superimposed with a high frequency is irradiated, and at the same time, the frequency is changed at several points as necessary, the AC output data is measured, the frequency characteristic is obtained, and this is recorded as calibration data. Similarly, the absolute amount of optical power can be obtained from the AC light receiving sensitivity characteristic of the monitor PD 22 obtained in advance, and the frequency and current amount are adjusted and calibrated so that the absolute amount becomes a predetermined value. Do.
After the above calibration, the wafer to be measured including the DUT 10 is set, and the following items are measured sequentially.

<Measurement of photosensitivity characteristics>
Step 1: The probe 11 is brought into contact with the DUT 10. In this state, a predetermined drive current is passed from the LSI tester 1 to the LED 15 via the coaxial cable 25 of the wafer measurement board 2.
At this time, the output relay switch S1 is turned off. For this reason, the AC signal from the AC signal source 52 is not input to the high frequency superimposing circuit 61, and high frequency superposition is not performed on the drive current.
When a predetermined drive current flows, the LED 15 emits light, and light enters the DUT 10 and the monitor PD 22 at a predetermined ratio (for example, the light reception power of the DUT 10 is several times to several tens of times that of the monitor PD 22).
The output of the DUT 10 is measured by an AC / DC voltmeter 57 in the LSI tester 1 and recorded.

  Step 2: The output of the monitor PD 22 is measured by the AC / DC voltmeter 58 in the LSI tester 1 and recorded.

Repeat steps 1 and 2 as necessary, changing the optical power at several points.
By calibrating the above measurement results against the recorded calibration data, an accurate DC light receiving sensitivity characteristic is obtained.

<Measurement of frequency characteristics>
Step 1: A predetermined drive current is supplied from the constant current source 51 of the LSI tester 1 to the high frequency superimposing circuit 61. Further, the correct DC output relay switch S1 is turned on by collating with the recorded calibration data, and the AC signal is supplied from the AC signal source 52 to the high frequency superposition circuit 61, and the AC signal is supplied to the constant current. A driving current is superimposed from the source 51. Then, the drive current on which the AC signal is superimposed is passed through the LED 15 in the measurement jig 50 via the coaxial cable 25 of the wafer measurement board 2.
When a predetermined drive current flows, the LED 15 emits light, and light enters the DUT 10 and the monitor PD 22 at a predetermined ratio (for example, the light reception power of the DUT 10 is several times to several tens of times that of the monitor PD 22).
The output of the DUT 10 is measured by an AC / DC voltmeter 57 in the LSI tester 1 and recorded.

  Step 2: The output of the monitor PD 22 is measured by the AC / DC voltmeter 58 in the LSI tester 1 and recorded.

Steps 1 and 2 are repeated as necessary, changing the frequency and / or optical power at several points.
By calibrating the result of the above measurement against the recorded calibration data, an accurate AC light receiving sensitivity characteristic is obtained.

In the present embodiment, the configuration and method for measuring the light receiving sensitivity characteristic at the time of AC superimposition have been described. However, when it is not necessary to measure the frequency characteristic, the high frequency superimposing circuit 61 is not necessary.
A semiconductor laser can also be used as the light source instead of the LED. In that case, if the drive current supplied to the semiconductor laser is set to be equal to or less than the threshold value, the LED light is obtained, and thus the above measurement method can be applied as it is.

[Second Embodiment]
The present embodiment is different from the first embodiment in that the inspection target is not a semiconductor wafer but an assembly (an optical device in which a chip is housed in a package).

FIG. 11 is a cross-sectional view illustrating a main part of the optical device measurement apparatus according to the second embodiment.
As is clear from comparison of FIG. 11 with FIG. 4, this optical device measurement apparatus includes an inspection jig 90 that holds an assembly (DUT 10) housed in a package, the auxiliary substrate 13 and the measurement on the inspection jig 90. A holding base 91 for holding the jig 50 is provided. This inspection jig 90 has all the functions of the wafer measurement board 2 including the probe card substrate 4 shown in FIGS. 3 and 4. The connection between the inspection jig 90 and the measurement jig 50 is achieved by the coaxial cables 25 and 31 and the power supply cable 28. Note that the role of the coaxial cable 32 shown in FIG. 4, that is, the connection between the DUT 10 and the inspection jig 90 is achieved by internal wiring (not shown) in the inspection jig 90.
In the comparison between FIG. 11 and FIG. 4, the configuration other than the above is the same as that in FIG. 4 described above, and the same reference numerals are given and description of the configuration is omitted.

In FIG. 11, the handler, the test head, the contact probe that is electrically connected to the DUT and the inspection jig, the socket that is mechanically fixed, the LED housing, and the like are not shown.
When the optical device measurement apparatus shown in FIG. 1 is applied to this embodiment, the wafer measurement board 2, the probe card substrate 4, the semiconductor wafer 6, the stage 7 and the contact ring 8 are omitted, and the inspection jig 90 shown in FIG. Used by being inserted into the connector 3b. For this reason, the structure of the prober apparatus 5 can be simplified and reduced in size.
An example of a specific test method is the same as that of the first embodiment, and thus description thereof is omitted.

  Note that the configuration of the measurement jig 50 in the embodiment of the present invention, particularly the reflective LED as the light source, is an LED illumination device with detection of radiation (illumination) performance degradation, for example, a backlight for LED panels or a general illumination lamp. Furthermore, it can be used for automobile headlights by incorporating a high-intensity white LED.

The optical device measurement apparatus and measurement method of this embodiment have the following advantages.
First, since the optical power is constantly monitored by the monitor PD 22, the DUT 10 can be measured with high accuracy.
Second, since no optical system member such as a lens is required, the measurement system can be reduced in cost and size.
Third, since an LED is used as the light source, the cost of the measurement system can be reduced. Moreover, replacement | exchange of LED is easy and maintenance property is also high.

Furthermore, there are the following advantages.
When the light shielding cover 30 is removed, it is safe because the LED stops emitting light.
Since the light incident on the monitor PD 22 is blocked by the light shielding cover 30 and the auxiliary substrate 13, the extraneous light other than the light from the LED 15 is blocked, so that the measurement value can be prevented from changing depending on the environment of the place of use.
Note that the optical device measurement apparatus and measurement method of this embodiment can be applied not only to a semiconductor wafer measurement system but also to an assembly measurement system. Further, a semiconductor laser can be used instead of the LED 15.
Further, the light source can be used as an LED lighting device with detection of deterioration in lighting performance, for example, for a backlight for an LED panel, a general illumination lamp, and a headlight for an automobile.

In particular, in the case of an LED, the radiation characteristics of the light emitting element (chip) itself are hardly deteriorated even after long-term use, but the material such as a resin sealing the chip is deteriorated by temperature and radiation energy of light. Therefore, although a predetermined drive current is applied, the light transmittance is lowered, and the light emission (illumination) performance is likely to be lowered.
Therefore, in the present embodiment, since the optical power itself is monitored by the monitor PD 22, the degree of deterioration can be grasped, so that there is no disadvantage due to the above performance reduction, that is, there is no reduction in measurement accuracy.

1 is a configuration diagram of an optical device measurement apparatus described in Patent Document 1. FIG. It is a block diagram of the optical device measuring apparatus of 1st Embodiment. It is an assembly drawing of a wafer measurement board and a probe card board. It is principal part sectional drawing of the optical device measuring apparatus of 1st Embodiment. It is an enlarged view of a reflection type LED part. It is a top view of a light shielding cover. It is an assembly drawing of the light shielding cover in the measurement jig. It is an electrical circuit diagram of the optical device measuring apparatus in an inspection state. It is a figure which shows the structure of the input-output line of a high frequency superposition circuit. It is a circuit diagram of a high frequency superposition circuit. It is principal part sectional drawing of the optical device measuring apparatus of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... LSI tester, 2 ... Wafer measurement board, 4 ... Probe card board, 5 ... Prober apparatus, 6 ... Semiconductor wafer, 7 ... Stage, 8 ... Contact ring, 10 ... DUT, 11 ... Probe, 12 ... Probe holder, DESCRIPTION OF SYMBOLS 13 ... Auxiliary board | substrate, 15 ... LED, 151 ... Light emitting element, 152a, 152b ... Lead, 153 ... Wire, 154 ... Reflective member, 154A ... Opening part, 155 ... Transparent epoxy resin, 156 ... Radiation member, 22 ... Monitor PD, 22A ... light receiving unit, 23 ... PD wiring board, 24a, 24b ... wire, 24c ... cable, 25, 31, 32 ... coaxial cable, 26,27,41 ... SMA male connector, 28 ... power supply cable, 30 ... Shading cover, 51 ... constant current source, 52 ... AC signal source, 53-56 ... voltage source, 57, 58 ... AC / DC voltmeter, 61 ... high frequency superposition circuit , 70: Photodiode, 71: Current / voltage conversion circuit, 72: Differential amplifier, R2: Resistance for impedance matching, R3: Feedback resistor, S1: Output relay switch, S2: Equivalent switch, A ... Anode, K ... Cathode , Vcc ... power supply voltage, Vee ... reference voltage

Claims (5)

A light emitting element that emits light to irradiate the device to be inspected, a reflective member that is provided on the opposite side of the light emitting element from the device to be inspected, and a part of which is open; A measuring jig to which a light receiving device that receives the monitor light passing therethrough and generates an output corresponding to the amount of light received by the monitor light is fixed;
Measuring at least one of the characteristics of the device under test and calibrating the measurement result based on the output from the light receiving device; and controlling power supply to the device under test during the measurement. A measuring unit to perform,
An optical device measuring apparatus. The measuring unit is
A high frequency superimposing circuit for superimposing an AC signal on a driving current supplied to the light emitting element;
A tester for measuring the characteristics by changing the frequency of the AC signal;
The optical device measurement apparatus according to claim 1. The measurement jig has a light shielding cover that covers the light emitting element, the reflecting member, and the light receiving device,
The optical device measurement apparatus according to claim 1, wherein the current supply to the light emitting element can be stopped in conjunction with the removal of the light shielding cover from the measurement jig. The connector of the cable for supplying an electric current to the light emitting element is provided on a substrate of the measurement jig to which the light shielding cover is fixed, and the connector also serves as a fixing means for the light shielding cover. The optical device measuring apparatus as described. A light emitting element that emits light to irradiate the device under test;
A reflective member that is provided on the opposite side of the device to be inspected of the light-emitting element and has a part opened;
An optical device measuring jig that is formed by fixing a light receiving device, which outputs from the light emitting element and passes through the opening of the reflecting member, and generates an output corresponding to the amount of received monitor light to a base substrate. Ingredients.

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