JP2003297884A - Photo-ic wafer inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo-IC wafer inspection device capable of inspecting a photo-IC wafer in a short time. <P>SOLUTION: The photo-IC wafer inspection device 10 is provided with a photodiode 17 for detecting light intensity inside an integrating sphere 11. The inspection device 10 is provided with a personal computer 14 for performing control to a DC source/monitor 12 so as to successively change the light intensity of a LED device 16. The inspection device 10 is provided with a probe card 21 for measuring the output level of a photo IC by the illumination of scattered light from an opening 15a when the light intensity of the LED device 16 is changed. On the basis of the photodiode output current of the photodiode 17 when the probe card 21 detects the change of the output level of the photo IC, the personal computer 14 calculates the threshold voltage of the photo IC. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photo IC wafer inspection device.

[0002]

2. Description of the Related Art A conventional photo IC wafer inspection apparatus includes a laser stabilizing light source, an optical attenuator (optical attenuator), a stage on which the photo IC wafer is mounted, and a contactor for contacting a pad of an IC chip on the photo IC wafer. It has a probe card.

The contact of the probe card is I
While the contactor is in contact with the pad of the C chip, the IC chip is irradiated with the laser light from the laser stabilizing light source through the optical attenuator, and the change in the output level of the IC chip is measured. ing.

In the optical attenuator, a metal film is formed on the transparent plate so that the thickness of the optical attenuator gradually increases in the rotation direction, and the light applied to the photo IC is rotated by rotating the optical attenuator with an electric motor. I try to change the strength. That is, each film thickness of the metal film of the optical attenuator is set in advance how many decibels the laser light (having a constant light intensity (power)) emitted from the laser stabilizing light source can be attenuated.

The photo IC wafer inspecting apparatus determines that the output level changes due to the light transmitted through the film thickness of the optical attenuator in a predetermined level range, and determines that the output level is good. I try to determine that there is no.

[0006]

By the way, conventionally, the light intensity for irradiating the light from the laser stabilizing light source to the IC chip of the photo IC wafer is changed in multiple steps,
A command signal is given to the electric motor to rotate the optical attenuator at each stage. The time required for rotation in one step is, for example, about 0.5 seconds, and since the number of steps to be changed is large, it takes a very long time to inspect one IC chip.
Since there are many photo IC chips on the wafer, there is a problem that it takes more time to inspect the photo ICs of one wafer in total.

An object of the present invention is to provide a photo IC wafer inspection apparatus which can perform a photo IC wafer inspection in a short time.

[0008]

According to a first aspect of the present invention, an integrating sphere that scatters light from a light source and guides scattered light to the outside through a predetermined opening, and a light intensity inside the integrating sphere. Detecting means, a stage arranged corresponding to the opening of the integrating sphere, on which a wafer having a photo IC mounted thereon is mounted, a drive current supply means for supplying a drive current of the light source, and the drive. Control means for controlling the current supply means to sequentially change the light intensity of the light source; and the photo IC
Measuring means for measuring the output level of the photo IC by illuminating scattered light from the opening when the light intensity of the light source is changed by the drive current supplying means. And a calculating means for calculating a threshold voltage of the photo IC based on a detection value of the detecting means when the measuring means detects a change in the output level of the photo IC. The subject is a wafer inspection device.

According to a second aspect of the present invention, in the first aspect, there is provided a determining means for determining whether or not the threshold voltage of the photo IC calculated by the calculating means is a predetermined level and outputting the determination result. And

According to a third aspect of the present invention, in the first aspect, the light source is an LED. According to a fourth aspect of the present invention, in any one of the first to third aspects, the control unit controls the drive current supply unit to change the light intensity of the light source so as to be sequentially increased, The calculating means calculates the threshold voltage of the photo IC based on a detection value of the detecting means when the measuring means detects a change in the output level of the photo IC.

[0012] The invention of claim 5 is the invention of claims 1 to 3.
In any one of the above items, the control unit controls the drive current supply unit to change the light intensity of the light source to be gradually reduced, and the calculation unit causes the measurement unit to output the output level of the photo IC. It is characterized in that the threshold voltage of the photo IC is calculated based on the detection value of the detecting means when the change of is detected.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. Figure 1 is a photo IC
2A is a schematic diagram showing a change in LED current, FIG. 2B is an explanatory diagram showing a change in photodiode output current I, and FIG. 2C is a schematic diagram showing a photo IC chip. It is explanatory drawing of the change of an output level.

The photo IC wafer inspection device (hereinafter referred to as inspection device 10) comprises an integrating sphere 11 and a DC source / monitor 1.
2. A wafer prober device 13 and a personal computer (hereinafter referred to as a personal computer 14) are provided. DC
The source / monitor 12 corresponds to a drive current supply means.

The integrating sphere 11 is provided with an integrating sphere body 15 which is a hollow sphere, and an LED as a light source is provided on the inner surface thereof.
The device 16 is fixed. The LED device 16 includes a plurality of LED elements. On the inner surface of the integrating sphere body 15, a photodiode 17 is attached as a detecting means for detecting the light intensity of the scattered light inside the integrating sphere 11. Also LED
In the vicinity of the device 16, on the inner surface of the integrating sphere body 15,
A baffle 18 is provided so as to block between the photodiode 17 and the LED device 16.

When light is emitted radially from the LED elements of the LED device 16, the light is multiply diffused and reflected by the highly diffusive reflective powder applied to the inner wall of the integrating sphere body 15. This diffusely reflected light is incident on the photodiode 17, and its output signal (photodiode output current I) is input to the DC source / monitor 12.
The DC source / monitor 12 measures the light intensity based on the output signal (photodiode output current I). The light intensity is the same when measured in any part of the spherical surface of the integrating sphere body 15, and is proportional to the luminous flux of the LED device 16 as a light source. That is, the light intensity is L of the LED device 16.
Driving current flowing through the ED element (hereinafter referred to as LED current)
Proportional to.

The opening 15a is formed on the lower surface of the integrating sphere body 15 and emits the diffusely reflected light to the outside.
The opening 15a has an opening area wider than the cross-sectional area of the light flux in general laser light.

The wafer prober device 13 includes a disc-shaped stage 20. Photo I on stage 20
The C wafer P is placed and fixed by a chuck (not shown). The stage 20 includes a drive device (not shown), and is rotatable and movable in any direction by the drive device.

An upper surface of the photo IC wafer P is a surface on which a large number of photo IC chips are formed, and an annular probe card 21 is provided facing the surface, and the probe card 21 has a circular shape coaxial with the probe card 21. A plurality of contacts (hereinafter, referred to as probes 22) are projected from the opening 21a to the lower surface side thereof. In the present embodiment, the number (three in the present embodiment) and the arrangement thereof are set so that the pads (not shown) provided on one photo IC chip can be contacted. In FIG. 2, only two probes 22 are shown. The three probes 22 are for power supply connection, grounding, and output, respectively.

These probes 22 are connected to the DC source / monitor 12 and are connected to the power source.
, A predetermined current is supplied from the DC source / monitor 12. The grounding probe 22 is a DC source / monitor 1
The pad contacting the grounding probe 22 via 2 is grounded. The output probe 22 outputs the output signal (voltage) V of the photo IC chip output from the pad in contact with the probe 22 to the DC source / monitor 12.

The probe card 21 has an opening 21.
The a is arranged so as to face the opening 15a of the integrating sphere body 15. That is, it is arranged so that uniform light from the integrating sphere body 15 is applied to the photo IC chip to be inspected through the opening 15a and the opening 21a.

Further, the DC source / monitor 12 applies a voltage between the respective pads 22 (pads for power supply connection and ground) while the probes 22 are in contact with corresponding pads of the photo IC chip. Alternatively, a current is passed to measure the voltage of the output pad to measure the characteristics of the photo IC chip.

The personal computer 14 includes a CPU, ROM and RAM
(Both are not shown), and the ROM is
A photo IC wafer inspection program is stored. The personal computer 14 corresponds to a calculation means, a control means, and a determination means.

Based on the photo IC wafer inspection program, the personal computer 14 outputs a control signal to the DC source / monitor 12 to control the DC source / monitor 12. Specifically, when the control signal is input, the DC source / monitor 12 can set the LED current to a multi-step constant value including from 0 to a predetermined maximum current based on the control signal. You can select a fixed value of.

In this case, when the LED current is sequentially increased from 0 (hereinafter referred to as the first control mode), and when the LED current is sequentially decreased from the maximum current toward the 0 side (hereinafter referred to as the second control mode). Is controlled.

As a result, in the case of the first control mode, the LED
The light quantity of the LED element of the device 16 can be set to a multi-step constant value in which the light quantity gradually increases from 0 to finally reach the maximum light quantity, and a constant value of one of these can be selected. become.

Further, in the case of the second control mode, the light quantity of the LED element of the LED device 16 can be set to a multi-step constant value in which the light quantity gradually decreases from the maximum light quantity and finally becomes 0. Of these, a fixed value in one stage can be selected.

On the other hand, the DC source / monitor 12 selects the constant value in any one of the stages and makes the LED device 16 emit light, and outputs the output signal (voltage) of the photo IC chip.
V is input, and the output signal V detects whether the photo IC chip has changed from a high level to a low level or from a low level to a high level.

Then, the DC source / monitor 12 outputs the detection result to the personal computer 14. Also, DC source /
The monitor 12 outputs the photodiode output current I at that time to the personal computer 14.

Based on the photo IC wafer inspection program, the personal computer 14 detects the change in the output signal (voltage) V of the photo IC chip, that is, the change in the output level, the change occurs. At this time, the photodiode output current I from the photodiode 17
Read the value of. Then, the personal computer 14 calculates the first threshold voltage or the second threshold voltage as the threshold voltage of the photo IC chip based on the value.

When the personal computer 14 is in the first control mode,
When the output signal (voltage) V changes from a high level (see H in FIG. 2 (c)) to a low level (see L in FIG. 2 (c)), the photodiode output current Ihl at that time The first threshold voltage Ehl of the IC chip is calculated by the following equation (1).

Ehl = C * Ihl (1) It should be noted that C is a constant, which is a value measured in advance in the dark room of the photodiode 17 using a power meter and is stored in the ROM in advance.

When the personal computer 14 is in the second control mode,
When the output signal (voltage) V changes from a low level (see L in FIG. 2 (c)) to a high level (see H in FIG. 2 (c)), based on the photodiode output current Ilh at that time, The second threshold voltage Elh of the IC chip is calculated by the following equation (2).

Elh = C * Ilh (2) In this way, the control in the first and second control modes is to calculate the threshold voltage according to the hysteresis because the photo IC chip has hysteresis. .

Then, the personal computer 14 determines whether the first threshold voltage Ehl calculated by the equation (1) and the second threshold voltage Elh calculated by the equation (2) are within the predetermined level range required for the photo IC chip. Determine whether or not. When it is within the predetermined level range, it is determined that the photo IC chip to be inspected is a non-defective product, and when it is not within the predetermined level range, the photo IC chip to be inspected is determined to be a defective product.

By outputting this defective product determination signal, marking is performed on the defective product by a known marking mechanism (not shown) based on this signal. next,
The features of the inspection device 10 configured as described above will be described.

(1) The inspection apparatus 10 of the present embodiment is L
The light from the ED device 16 (light source) is scattered and the opening 15a is formed.
Integrating sphere 11 for guiding scattered light to the outside via
A photodiode 17 (detection means) for detecting the internal light intensity is provided. In addition, the inspection device 10 is arranged corresponding to the opening 15a of the integrating sphere 11, and has a stage 20 on which a photo IC wafer P having a photo IC mounted thereon is mounted and an LED.
DC source / monitor 12 for supplying drive current for device 16
(Driving current supply means).

The inspection device 10 is a DC source / monitor 1
2 is provided with a personal computer 14 (control means) for controlling the light intensity of the LED device 16 so as to be sequentially changed. or,
The inspection apparatus 10 includes a plurality of probes 22 (contacts) that come into contact with the pads of the photo IC, and the DC source / monitor 1
The probe card 21 (measuring means) for measuring the output level of the photo IC by illuminating scattered light from the opening 15a when the light intensity of the LED device 16 is changed by 2 is provided. Then, further, the probe card 21 is a photo I.
Based on the photodiode output current I (detection value) of the photodiode 17 when the change in the output level of C is detected, the first threshold voltage Ehl and the second threshold voltage Ehl of the photo IC are detected.
A personal computer 14 (calculating means) for calculating lh was provided.

As a result, the DC source / monitor 12 is LE
When the light intensity of the D device 16 is sequentially changed, the light intensity can be changed step by step, unlike the case where the conventional optical attenuator is driven by a motor. Conventionally, the motor drive mechanically drives the optical attenuator, which requires about 0.5 seconds for each step. However, in the present embodiment, the adjustment of the light intensity for each step is as follows. For example, a few μ
The level is in the range from sec to several msec, which can be greatly shortened. Since the change of the light intensity is performed in one photo IC chip in multiple stages (many times), there is an effect that the inspection time for one photo IC chip can be totally shortened. In addition, the inspection time for one wafer can be greatly shortened as compared with the conventional one.

In the conventional optical attenuator, the light intensity level is changed by changing the thickness of each metal film on the transparent plate, but the area of the transparent plate is limited. There is a problem that the resolution of light intensity cannot be easily increased.

However, in this embodiment, the resolution of the light intensity can be set by the value of the LED current, so that the resolution can be increased. Further, in the present embodiment, the intensity of the light emitted to the outside through the opening 15a and the intensity of the light received by the photodiode 17 are always in the same relationship by using the integrating sphere 11. Therefore, the light intensity that becomes the threshold voltage of the photo IC can be accurately measured.

Further, since the cross-sectional area of the laser light to be irradiated is narrow in the related art, it is necessary to position the photo IC chip strictly within the luminous flux of the laser light. On the other hand, in this embodiment, the uniform light from the integrating sphere body 15 passes through the opening 15a wider than the cross-sectional area of the laser light, and the photo IC to be inspected.
This is a configuration for irradiating the chip. Therefore, the opening 15a
All you have to do is to attach a photo IC chip to
Positioning for irradiating the C wafer P with light can be performed more roughly than before.

(2) In the inspection device 10 of this embodiment,
The personal computer 14 is the first threshold voltage Ehl of the photo IC chip.
And determining whether the second threshold voltage Elh is at a predetermined level,
The determination means outputs a determination signal.

As a result, the quality of the photo IC chip can be efficiently judged. (3) The inspection device 10 of the present embodiment uses the LE as the light source.
It is a D element. It is known that the LED element is less aged than other light sources, for example, a laser-stabilized light source, but it is still aged. However, even in this case, since the value of the LED current is changed and the photo diode output current is detected to inspect the photo IC, it is not affected by aging deterioration, that is, aging deterioration is caused. It can be measured as if it were not present.

On the other hand, conventionally, when the laser stabilizing light source deteriorates with age, it is necessary to change the laser stabilizing light source to a new one. (4) In this embodiment, the personal computer 14 (control means) is the DC source / monitor 12 (driving current supply means).
Was controlled to change the light intensity of the LED device 16 to be gradually increased. Then, at this time, the personal computer 14 detects the change in the output level of the photo IC chip by the probe card 21 (measuring means) based on the photodiode output current I (detection value) of the photo diode 17 and determines whether the photo IC 1 The threshold voltage Ehl (threshold voltage) is calculated.

As a result, the first threshold voltage Ehl (threshold voltage) of the photo IC chip can be easily obtained. (5) In this embodiment, the personal computer 14 (control means)
Controls the DC source / monitor 12 (driving current supply means) so that the light intensity of the LED device 16 is gradually reduced. Then, at this time, the personal computer 14 uses the photo diode output current I (detection value) of the photo diode 17 when the probe card 21 (measuring means) detects a change in the output level of the photo IC chip, based on the photo IC chip output current I (detection value). The second threshold voltage Elh (threshold voltage) is calculated.

As a result, the second threshold voltage Elh (threshold voltage) of the photo IC chip can be easily obtained. (6) In this embodiment, the LED device 16 is integrated into the integrating sphere 11.
Placed inside. As a result, the LED device 16 is moved to the integrating sphere 11
Since it is not provided outside, the inspection device 10 itself can be made compact.

The embodiment is not limited to the above embodiments, but may be modified as follows. In the above embodiment, the LED device 16 includes the integrating sphere 11
Although it is arranged inside, it may be arranged outside the integrating sphere 11 so that the light of the LED device 16 enters the integrating sphere 11.

In the above-described embodiment, the photodiode 17 is used as the detecting means, but other detecting means may be used as long as it can measure the light intensity and has linearity between the input and the output.

In the above embodiment, the DC source / monitor 12 supplies the LED current in multiple stages including 0 to a predetermined maximum current based on the control signal in the first and second control modes. However, it may be linearly changed and supplied.

Next, technical ideas other than the invention described in the claims which can be grasped from the above-described embodiment will be described below together with their effects. (1) The photo IC wafer inspection apparatus according to claim 1, wherein the light source is arranged in an integrating sphere.

In this case, since the light source is not provided outside the integrating sphere 11, the inspection device 10 itself can be made compact.

[0052]

As described above in detail, according to the first to fifth aspects of the invention, there is an excellent effect that the photo IC wafer inspection can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an inspection apparatus of this embodiment.

FIG. 2A is an explanatory diagram showing changes in LED current,
(B) is an explanatory view showing the change of the photodiode output current I, and (c) is an explanatory view of the change of the output level of the photo IC chip.

[Explanation of symbols]

10 ... Inspection device (photo IC wafer inspection device) 11 ... Integrating sphere 12 ... DC source / monitor (driving current supply means) 13 ... Wafer prober device 14 ... Personal computer (calculation means, control means,
Determining means 15 ... Integrating sphere body 15a ... Opening 16 ... LED device (light source) 17 ... Photodiode (detecting means) 20 ... Stage 21 ... Probe card (measuring means) 22 ... Probe (contact) P ... Photo IC wafer Elh: first threshold voltage (threshold voltage) Elh: second threshold voltage (threshold voltage)

Claims (5)

[Claims] 1. An integrating sphere that scatters light from a light source and guides scattered light to the outside through a predetermined opening, a detection unit that detects the light intensity in the integrating sphere, and an opening of the integrating sphere. , A stage on which a wafer having a photo IC mounted thereon is mounted, a drive current supply means for supplying a drive current of the light source, and a light intensity of the light source is sequentially changed with respect to the drive current supply means. And a plurality of contacts for contacting the pads of the photo IC, and when the light intensity of the light source is changed by the driving current supply means, the scattered light from the opening is illuminated. A measuring means for measuring the output level of the photo IC, and a threshold voltage of the photo IC based on a detection value of the detecting means when the measuring means detects a change in the output level of the photo IC. Calculation A photo IC wafer inspection apparatus comprising means. 2. The photo IC according to claim 1, further comprising a determination unit that determines whether or not the threshold voltage of the photo IC calculated by the calculation unit is at a predetermined level and outputs the determination result. Wafer inspection equipment. 3. The photo IC wafer inspection apparatus according to claim 1, wherein the light source is an LED. 4. The control means controls the drive current supply means to change the light intensity of the light source so as to be sequentially increased, and the calculating means causes the measuring means to change the output level of the photo IC. 4. The photo IC wafer inspection apparatus according to claim 1, wherein the threshold voltage of the photo IC is calculated based on the detection value of the detection means at the time of detection. 5. The control unit controls the drive current supply unit to change the light intensity of the light source so as to be gradually reduced, and the calculation unit causes the measurement unit to change the output level of the photo IC. 4. The photo IC wafer inspection apparatus according to claim 1, wherein the threshold voltage of the photo IC is calculated based on the detection value of the detection means at the time of detection.