JP3197325B2 - Semiconductor test equipment using optical signals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test apparatus for testing high-speed devices and integrated circuits formed on a gallium arsenide substrate. More specifically, it is an object of the present invention to provide an improved device that can measure a pulse characteristic of a high-speed device under test with high accuracy by applying an optical signal.

[0002]

2. Description of the Related Art The capacity and speed of an information processing system have been increasing, and an information processing system for processing its signal has been demanded to have high speed in hardware and software. In particular, on the hardware side, the use of a semiconductor substrate having high mobility of carriers such as gallium arsenide has increased the speed, and has been responding to the needs of the market by making the pattern finer and more highly integrated. Such gallium arsenide integrated circuits are now being developed by semiconductor manufacturers. For example, the HS6900 series of logic ICs manufactured by Hitachi, Ltd. has a high-speed signal processing of 2.4 gigabits / sec. Gigabit Logic, Inc.) 10G
PicoLogic Family
y) guarantees operation at 3 GHz.

In the development and inspection of such a high-speed integrated circuit, a signal having a clear skew relationship (timing relationship) such as a high-speed clock signal and a data signal is used in order to confirm its performance. It is necessary to input in the chip, and it is necessary to know the margin. In addition, it is necessary to observe a high-speed signal output from an integrated circuit (IC).

At present, in order to perform such an evaluation, a method in which an IC is mounted on a dedicated device and connected to an external pulse pattern generator or a sampling oscilloscope via a connector of the device, and an on-wafer probe There is a method of connecting directly to dedicated pads on the wafer and connecting to external equipment. However, in most cases,
Rather than cutting chips out of the wafer and mounting them in a dedicated device for inspection, they measure the resistance and capacitance values at points on the wafer before cutting, and simulate the characteristics by calculation from their time constants. Alternatively, a test single element is arranged at the edge on the wafer, and the characteristics are inferred.

[0005]

SUMMARY OF THE INVENTION When measuring characteristics by mounting the device on a measuring device, it is necessary to comprehensively evaluate the performance of the device, the characteristics of the mounting method, and the characteristics of the object to be measured. Become. There is no problem when the characteristics of the measuring device are sufficiently higher than the characteristics of the device under test.However, when the characteristics are comparable, the characteristics of the device under test cannot be accurately measured unless the characteristics of the device itself are clarified. Can not know. However, the higher the signal speed, the more difficult it is to design an interface with the input / output connector, and the shape of the input / output connector is determined by the size of the externally connected measuring device. Then, the size of the device itself becomes considerably large, and the size causes a difference in the distance to the IC and the propagation time between the input connectors, so that it is very difficult to accurately know the timing dependency and the phase margin. There was a problem to be solved.

In addition, since the number of signal lines for connecting the wafer to the measuring apparatus is increased, there remains a problem that the measuring connector cannot be frequently connected to or disconnected from the wafer.

In the on-wafer probe, a dedicated pad (measurement terminal) needs to be provided, and the probe must be in direct contact with the wafer, which may cause a scratch. Also, it is necessary to design and produce a dedicated prober card for the IC each time. The high-frequency characteristics of the wafer probe have a measurable frequency range from DC to 50 GHz in the WPH series of CASCADE MICROTECH in the United States. Since the measurement of such high-frequency characteristics is performed using a network analyzer, the characteristics of the measurement system can be canceled within a certain range by applying a correction, and the frequency characteristics of the prober do not cause much problem. However, when observing the skew in real time, it is necessary to input and output a high-speed pulse, and such a prober cannot introduce a high-speed signal without deterioration. In addition, in order to adjust the skew of the IC, it is necessary to know the propagation delay time of the transmission line of the IC accurately, but if such a time domain (time domain) measurement cannot be performed on a wafer, it must be solved. There was a problem that had to be done.

[0008] In the stage of IC development and inspection, there is a strong demand that a high-speed signal be introduced into the IC in a non-contact manner at the same time on multiple channels and that a signal at an arbitrary point on the IC be observed. Non-contact probing using the electro-optic effect has been studied for observation of signals at arbitrary points (Reference IBM Journal of Research and Development V
ol.34, No.2 / 3, March / May 1990 P.141-172 and 1990 IEICE Autumn Conference C291,
292, 293). Even if only such probing is developed, if the signal cannot be introduced into the circuit under test, the system is incomplete. In order to solve this problem, research has been started to build a high-speed signal source on the circuit chip under test, eliminate the problem of bonding wires and connectors, and know the characteristics of the circuit (NTT R & D Vol. 40N).
o. 1 1991). In this system, a photoelectric conversion element is formed on a chip. However, since the optical signal source of this system is an impulse, it is suitable for knowing the impulse response of the element, but there is a problem in evaluating the entire circuit. Further, since the mode locking method is used for this optical signal source, there remains an unsolved problem that an arbitrary repetition frequency cannot be selected.

Introducing a pulse signal having a rise time of more than 10 ps, which is a measurement signal, to a device to be measured or an integrated circuit to be measured on a wafer substrate by a prober or the like requires a prober or a rise time of a signal between the prober and the substrate. There is a problem to be solved in that it is extremely difficult to cause deterioration, and it is not easy to correct such deterioration of the pulse signal by calculation.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and in order to eliminate the deterioration of a high-speed pulse, a non-contact, relatively low-speed measurement signal is used by using an optical signal. Was introduced on the wafer, and the rise time was improved on the wafer to introduce a high-speed signal to the device under test or the integrated circuit (IC) under test.

As a means for introducing a high-speed signal into an IC without contact, a light-triggered high-speed signal generator integrating a photoconductor, a non-linear transmission line, and a waveform shaper is mounted on the same wafer substrate as the device under test and the circuit under test. Formed on top, it was configured to test high speed devices and ICs on a wafer substrate.

By integrating one or more of the optical trigger high-speed signal generators on a wafer, a non-contact high-speed signal can be transmitted to a device to be measured or an IC on the wafer.
Can be introduced above. The light trigger signal can be introduced into the light trigger high-speed signal generator on the wafer in a contactless manner through the space. In order to introduce this optical signal into an IC, etc., by integrating and using a plurality of tapered optical fibers in the form of a tapered optical fiber tip, multi-channels can be used for the minute input of the integrated circuit on the wafer. Optical signal can be introduced. By using an optical delay circuit for skew adjustment between channels, jitter does not occur, and furthermore, deterioration of waveform quality due to delay is prevented. This enables accurate setting of the skew between channels. Since the photoconductor has a simpler structure than the photodiode, it can be easily formed on the gallium arsenide wafer substrate on which the device under test or the device under test is formed, together with the nonlinear transmission path and the waveform shaper.

[0013] The rise time is several tens due to the nonlinear transmission path.
Since the signal of 0 ps can be reduced to 10 ps or less, high speed is not required for the optical trigger signal input to the photoconductor. Therefore, there is no need to use a signal source such as a dye laser that generates high-speed light pulses, which is inconvenient to handle and has a fixed repetition frequency. It is easy to handle, and a semiconductor laser that can change the repetition cycle over a wide range. Can be used without pulse width compression.
Even when the photoconductor is on, its impedance is large and several kilo-ohms, and the output of the photoconductor can be terminated by the impedance of the non-linear transmission line. Therefore, the VSWR (voltage standing wave ratio) of the non-linear transmission line itself and the load is poor. Even if a reflected wave is generated, it can be absorbed by this terminator. Also, since the photodiode is a current source, the signal that can be extracted even when the bias is changed is the same.However, if a large bias voltage is applied to the photoconductor adopted in the present invention, a large signal can be extracted. Is possible. 2-3 generated by photoconductor
A signal having a rise time of about 50 ps at V is shaped into a rise time of 10 ps or less by an optimized nonlinear transmission line, and shaped into a desired pulse width by a directional coupler or the like.

By forming the photo-triggered high-speed signal generator in which the photoconductor, the nonlinear transmission path, and the waveform shaper are integrated on the same wafer substrate as the device to be measured and the IC to be measured, Can be introduced into high-speed devices and ICs on a wafer substrate.

Further, by forming a conventional wide band sampling gate or a wide band photo sampling gate on the same wafer as the IC or device to be measured, a high-speed signal is sampled on the wafer substrate,
The signal is converted into a low-speed signal by a stretcher circuit that is a sampling gate to eliminate signal deterioration due to an interface with an external measuring instrument such as a prober or a measuring jig. Observation was made possible, and it was extremely easy to extract signals from the wafer.

Since these measuring circuits are connected to the input / output terminals of the circuit to be measured, it is inconvenient when the circuit to be measured is operated normally after the measurement is completed. Therefore, it is desirable that the measurement circuit be completely separated from the circuit to be measured after the measurement is completed. The measurement circuit can be completely separated from the circuit to be measured by scribing on the wafer substrate, so that after the measurement is completed, the original operation of the IC becomes possible.

Also, by using a sampling method utilizing the electro-optic effect, it is possible to observe a signal at an arbitrary point in a non-contact manner.

[0018]

By integrating the photoconductor, the non-linear transmission line, the waveform shaper, and the sampling gate on the gallium arsenide wafer substrate in this manner, the device can be miniaturized, and high-speed signals can be received in a non-contact manner. High-speed signal information can be easily taken out from a wafer substrate by being introduced into a measurement circuit or a device under test, and a high-speed IC test can be performed. In addition, a non-contact high-speed IC test apparatus can be realized by combining with a sampling method using the electro-optic effect.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIG. 1 and will be described with reference to FIG.

A high-speed signal generator using a light trigger according to the present invention is integrated on a gallium arsenide wafer 10 to be measured together with an integrated circuit to be measured and a device to be measured. here,
12 is an integrated circuit to be measured, 14 is a device to be measured, 100 is an optical trigger high-speed signal generator, 109 is a transmission line for evaluating the optical trigger high-speed signal generator 100, and 102 is included in the optical trigger high-speed signal generator 100 This is a diode capacitance inspection cell for inspecting the capacitance of the obtained diode.

When developing a high-speed and large-scale integrated IC, only a few chips of the integrated circuit under test 12 are mounted on the gallium arsenide wafer 10, and the gallium arsenide wafer 10 is used to know the high frequency characteristics. A device under test 14 such as a transistor device manufactured in the same process as the integrated circuit 12 under test is arranged in a part. Therefore, a light-triggered high-speed signal generator 100 that can be triggered by an optical signal is formed in an empty space on the gallium arsenide wafer 10 and a high-speed pulse signal can be applied to the device under test 14 or the integrated circuit under test 12. it can. The diode capacitance test cell 102 can easily measure the reverse voltage versus capacitance characteristics of the diode that governs the performance of the nonlinear transmission path included in the light-triggered high-speed signal generator 100.

FIG. 2 shows a detailed configuration of the optical trigger high-speed signal generator 100 which is an important component of FIG.

Reference numeral 122 denotes a photoconductor for converting the light trigger 121 into an electric signal, and reference numeral 124 denotes a bias terminal for applying a bias to the photoconductor 122, and 127.
Reference numerals -1 and 127-2 denote terminating resistors for absorbing a pulse signal reflected from the nonlinear transmission line 125. Many D1s included in the nonlinear transmission line 125 are reverse-biased by the pulse signal from the photoconductor 122. A Schottky barrier type diode arranged so as to apply a voltage, 141 is a waveform shaper using a directional coupler, 128
Is a terminating resistor for absorbing a signal passing through the directional coupler 141, 159 is an output terminal which is a transmission line for outputting a signal shaped by the waveform shaper 141, and 147 is an output terminal 159. This is a terminating resistor for absorbing the signal reflected from the side.

FIG. 3 shows waveforms at various points in the configuration of FIG.
The operation will be described using this. When the optical trigger signal 121 shown in FIG. 7A is incident on the photoconductor 122 connected to a bias power supply (not shown), the conductance of the photoconductor 122 changes according to the power of light, A current corresponding to the light trigger signal 121 flows through the photoconductor. Photo conductor 1
The conductance transition at the time of incidence of light 22 is very fast. The output (b) of the photoconductor 122 is input to the nonlinear transmission line 125. The non-linear transmission line 125 has an optimum number of diodes D1 arranged at optimum intervals along the center conductor 129 forming a coplanar transmission line with the ground pattern 160 in a direction reversely biased by the output signal of the photoconductor 122. (Literature Appl. Phy. Lett. 54 (11), 131989 3
Month).

FIG. 4 shows the nonlinear transmission line 125 shown in FIG.
2 shows the capacitance C _D1 (pF) between the terminals of the diode D1 when a reverse voltage is applied to the plurality of diodes D1 included in FIG.

The capacitance between the terminals of the diode D1 changes non-linearly with a change in voltage. The propagation speed V of the signal on the center conductor 129 can be expressed by 1 / (LC) ^1/2 ,
In the nonlinear transmission path 125, since the diode D1 is arranged on the line, the center conductor 129 and the ground
The capacitance C _{D1 of the} diode _D1 is added to the capacitance C of the transmission line formed by the pattern 160, and the propagation speed V becomes 1 / ｛L
(C + C _D1 ｝ ^1/2 . That is, the propagation speed changes according to the transient response of the signal. For example, in the case of the positive polarity of the pulse signal and the transient response at the rising edge, the capacitance decreases as the signal rises, so the propagation speed increases. From such a phenomenon, when a pulse signal with a short transition time is input, the high voltage portion follows the low voltage portion in time, and the transition time changes. Can be shortened.

The pulse signal whose transition time has been shortened by the nonlinear transmission line 125 (FIG. 3C) is input to a waveform shaper 141 which is a directional coupler. Waveform shaper 141
Is connected to the nonlinear transmission line 125, and the other end is connected to the terminating resistor 1 of the characteristic impedance of the waveform shaper 141.
Terminate at 28. Non-linear transmission line 16 of coupled transmission line
One end of 0 is an output terminal 159, and the other end is terminated by a terminating resistor 147 having the characteristic impedance of the directional coupler.

The waveform shaper 141, which is a directional coupler,
When a pulse having a width equal to or longer than the coupling time is input, the signal propagates as it is, and a signal that is absorbed by the terminator 128 and a signal that splits into a coupling line are generated. The pulse width of the signal divided into the coupling line becomes the coupling time length of the coupling line. Also, the transition time of the trailing edge of the pulse is equivalent to the leading edge. Therefore, the pulse signal having a certain width has the same positive and negative transitions, and the pulse signal having the predetermined pulse width shown in FIG.
, And output from the output terminal 159 and applied to the integrated circuit under test 12 and the device under test 14. At this time, if the matching with the integrated circuit under test 12 or the device under test 14 is poor, reflection occurs.
Mostly absorbed by 47. Reference numeral 144 denotes a bonding wire that suppresses the occurrence of an odd mode of the coplanar line caused by the ground pattern 160 becoming asymmetric.

FIG. 5 shows a diode capacitance test cell 102.
Details of FIG. 1 are shown. This is for measuring the terminal-to-terminal capacitance characteristic (FIG. 4) of the diode D1 forming the nonlinear transmission line 125 included in the optical trigger high-speed signal generator 100 shown in FIG. In order to achieve the above, the terminating resistors 127-1, 127-2, 12
8 and 147 are removed (147 need not be removed), and the light-triggered high-speed signal generator 10
Through the same steps as in step 0, a gallium arsenide substrate 10 (FIG. 1) is formed.

Transmission line 109 formed on gallium arsenide substrate 10 connected to optical trigger high-speed signal generator 100
The round-trip propagation time of the line length shown in FIG. 1 is larger than the pulse width of the pulse (FIG. 3D) obtained from the output terminal 159 of the optical trigger high-speed signal generator 100. This is the pulse output of the optical trigger high-speed signal generator 100 (FIG. 3).
(D) is used to observe and evaluate the performance of the light-triggered high-speed signal generator 100.

FIG. 6 shows a second embodiment of the present invention. The difference from the first embodiment shown in FIG. 1 is that a wideband sampling gate 200 and a diode capacitance test cell 202 are formed on a gallium arsenide substrate 10. A high-speed pulse signal from the optical trigger high-speed signal generator 100 (FIG. 3)
(D)) by applying a high speed pulse output was slow with a broadband sampling gate 200 as the signal to be measured signal to be measured from the measured integrated circuit 12 and the device under test 14
A more moderate sampling output is obtained and can be observed. Broadband sampling gate 2
00 includes a non-linear transmission line using a diode as in the case of the optical trigger high-speed signal generator 100.
The diode capacitance test cell 202 is used to test the diode terminal capacitance (pF) (FIG. 4) with respect to the reverse bias voltage of the diode.

FIG. 7 shows a wideband sampling gate 20.
A sampling circuit containing zeros is shown. Here, a signal from the signal source 231 which is an output of the integrated circuit under test 12 or the device under test 14 is received as a signal to be measured at the input terminal 233, terminated by the terminating resistor 234, and the Schottky barrier for sampling is used. Diode 23 which is a diode
At 5,236, sampling pulses 237 and 238 are applied via capacitors 241 and 242 for memory to sample the signal to be measured from the signal source 231. Charges proportional to the voltage of the sampled signal are accumulated in the capacitors 241 and 242, and become slower than the signal to be measured from the signal source 231 via the resistors 251 and 252.
Voltage of the sampled signal is taken out, which is the sampling output of the wideband sampling gate 200. Here the resistance 253 and 254 supply -V _C and V _C
And the diodes 235 and 236 are appropriately biased through the resistors 251 and 252.

The sampling output , which has become gentler than the signal to be measured , is amplified by the amplifier 261 via the resistors 255 and 256 and stored in the capacitor 243 via the switch 265. This is a slow sampling gate, operating as a stretcher. Capacitor 2
The signal accumulated in 43 is amplified by an amplifier 262, and an amplified sampling output is obtained from an output terminal 269 thereof.

FIG. 8 shows a signal under test from the signal source 231 which is an output signal of the integrated circuit under test 12 and the device under test 14.
Wideband sampling gate 2 for observing a high-speed signal
FIG. 7 shows a configuration in which the portion of FIG. 7 (FIG. 7) is formed on the gallium arsenide substrate 10.

A photoconductor 222 is formed between the conductors 217 and 219,
6, a bias power supply 215 is connected. When the light trigger 221 is irradiated on the photo conductor 222, the conductance changes and a trigger signal corresponding to the light trigger is generated between both ends of the photo conductor 222, that is, between the conductors 217 and 219. This trigger signal travels over conductors 218 and 219 via a capacitor 240 for blocking bias from bias power supply 215 and propagates to a non-linear transmission line 225 containing many diodes D2. Here, since the capacitance (pF) between the diode terminals with respect to the reverse bias voltage of the diode D2 has the characteristic shown in FIG. 4, the transition time (rise time) of the trigger signal is the same as in the case of the nonlinear transmission line 125 in FIG. Is accelerated and arrives at the right end of conductors 218 and 219. At the right end, an air bridge 249 made of wire bonding or metal foil short-circuits both conductors 218 and 219, and functions as a short stub for the positions of capacitors 241 and 242. Narrow positive and negative sampling pulses are applied to conductors 245 and 246.
To the diodes 235 and 236 for sampling, to make the diodes 235 and 236 conductive for a short period of time, and the signal source 2 applied to the input terminal 233
31 is sampled, the amplitude component of the signal is stored in capacitors 241 and 242,
2, a signal which is slower than the signal under measurement is extracted. The terminating resistor 234 is at a position for terminating a signal from the input terminal 233, and the terminating resistor 239 is at a position for terminating a pulse reflected from the air bridge 249 and the nonlinear transmission line 225.

FIG. 9 shows the structure of the capacitor 242 formed on the conductor 219, and the sampling pulse is supplied through the capacitor 242 to the conductor 246.
To turn on the diode 236. 8A shows the conductor 246 and the gallium arsenide substrate 10 viewed from the resistor 253 side in FIG.
FIG. 13 is a side sectional view of a conductor 219 formed thereon and a dielectric 248 inserted therebetween. FIG. 9B is a cross-sectional view of the conductor 246, the conductor 219 formed on the gallium arsenide substrate 10, and the dielectric 248 interposed therebetween when the air bridge 249 side is viewed from the nonlinear transmission line 225 side. FIG. Capacitor 242 that accumulates the sampled signal through sampling pulse 238
Inserts the dielectric 248 and inserts both conductors 246 and 219
Is formed between. The capacitor 241 is formed by the completely same structure.

The case where the wideband sampling gate 200 shown in FIGS. 7 and 8 is formed on the gallium arsenide substrate 10 has been described above. However, portions other than the wideband sampling gate 200 in FIG. 7, that is, the resistors 253 to 256, the amplifier 261, and the switch 2 called a second sampling gate or a stretcher
It should be apparent that 65, capacitor 243, and amplifier 262 may also be formed on gallium arsenide substrate 10 integrally with broadband sampling gate 200.

FIGS. 10 and 11 show the case where the characteristics of the device under test are measured using the light-triggered high-speed signal generator 100 and the wideband sampling gate 200 formed on the gallium arsenide substrate 10 shown in FIG. The example of the system and the waveform of each part are shown.

When a trigger signal for starting the system is applied to the input terminal 20, it is converted by the trigger generator 21 into a signal having a constant amplitude and pulse width (FIG. 11).
(A)) is applied to the light trigger generator 22. The optical trigger generator 22 includes a laser diode, which emits light (FIG. 11B), is branched into two, and applied to optical delay circuits 23-1 and 23-2. The light trigger 121 (FIG. 11)
(C)) and 221 (FIG. 11 (g)) are obtained.

The optical trigger 121 is applied to the optical trigger high-speed signal generator 100 whose details are shown in FIG. 2. When the conductance of the photoconductor 122 is changed, the optical trigger 121 is converted into an electric signal and input to the nonlinear transmission line 125. Then, a waveform in which the rise time of the leading edge of the signal is compressed is obtained (FIG. 11D). This is because the pulse width is narrowed by the waveform shaper 141, the pulse trailing edge is shaped, and output from the output terminal 159 (FIG. 11 (e)). Measurement object 15
Is applied to In the measured object 15 thereby operates to output a signal to be measured this is applied to the input terminal 233 of the broadband sampling gate 200 of FIG. 7 and FIG. 8
The signal becomes a signal source 231 (FIG. 11F).

The light trigger 221 is applied to the wideband sampling gate 200 (see FIGS. 7 and 8) at the time shown by the solid line in FIG. 11 (g) or at the time shown by the broken line variably delayed by a minute time. The pulse is applied and generated in the photoconductor 222 included therein, and the leading edge of the pulse is compressed (fast rise) in the nonlinear transmission line 225 (FIG. 11 (h)), and the air bridge 249 is formed. Positive and negative sampling pulse 2 reflected by
37 and 238 (FIG. 11 (i)), which turn on the sampling diodes 235 and 236 to perform the sampling operation. The signal to be measured from the signal source 231
The sampling output obtained by sampling the signal
The waveform is extracted from the resistors 251 and 252 as a waveform gentler than the signal , amplified, stretched by a hold operation, and obtained at an output terminal 269 of the sampling circuit. Here, the sampling output obtained from the resistors 251 and 252 is
Since the signal is lower in speed than the signal to be measured from the signal source 231 , the signal can be easily extracted from the gallium arsenide substrate 10 to the outside and processed in the signal processing circuit 29.

FIG. 12 shows a broadband photo sampling
A sampling circuit including a gate 201 is shown.
This is another embodiment of the sampling circuit shown in FIG. 7, in which photoconductors 223 and 224 are used in place of diodes 235 and 236 (FIG. 7), and optical sampling and
The difference is that the pulse 111 is incident. The photoconductors 223 and 224 are the diodes 23 shown in FIG.
5,236, and the capacitors 241 and 242 are replaced with the capacitors 245 and 246, and the terminating resistor 234 is used.
The resistors 251 and 252 can be formed on the gallium arsenide substrate 10 in the same manner as in FIG.

In this case, the optical sampling pulse 111
Is supplied from a device separate from the gallium arsenide substrate 10. It will be clear from the above description that the wideband photo sampling gate 201 can be used in place of the wideband sampling gate 200 on the gallium arsenide substrate 10 shown in FIG.

FIGS. 13 and 14 show the configuration and the waveforms of the respective parts when the device under test shown in FIG. 6 is measured by the system including the wideband photo sampling gate 201 shown in FIG.

When a trigger signal for starting the system is applied to the input terminal 20, it is converted by the trigger generator 21 into a signal of constant amplitude and pulse width (FIG. 14).
(A)) is applied to the optical trigger generators 22-1 and 22-2. The light trigger generators 22-1 and 22-2 include laser diodes, respectively, which emit light and are applied to the optical delay circuits 23-1 and 23-2, respectively (FIG. 14B ), (G)).

In the optical delay circuits 23-1 and 23-2,
One of the optical signals delayed by a predetermined amount is the optical trigger 12.
1 (FIG. 14 (c)), the light-triggered high-speed signal generator 10
0 (see FIG. 2), the rising portion thereof is speeded up by the nonlinear transmission line 125 included therein,
4 (d)), the pulse width is narrowed by the waveform shaper 141, and the trailing edge of the pulse is waveform-shaped, and the output terminal 15
9 (FIG. 14 (e)), the integrated circuit under test 1
2 and the device under test 15 which is the device under test 14.
The device under test 15 operates accordingly to output a signal, which is the broadband photo sampling gate 20 of FIG.
1 of the signal under test applied to the input terminal 233
31 (FIG. 14F).

The output of the optical trigger generator 22-2 (FIG. 14)
(G)) in FIG. 14 (h) in the optical delay circuit 23-2.
At the time indicated by the solid line, or at the time indicated by the dashed line variably delayed by a minute time, and applied to the optical pulse compressor 25. The optical pulse compressor 25 compresses the pulse width of the optical pulse of FIG. 14 (h) to several ps to obtain an optical sampling pulse 111 (FIG. 14 (i)).
Of the photoconductors 223 and 224 (FIG. 12) to perform a sampling operation. The subsequent operation is shown in FIG.
This is the same as the system shown in FIG.

FIG. 15 shows a third embodiment of the present invention. 6 is different from the second embodiment shown in FIG. 6 in that an electro-optic crystal 60 for detecting the output of the integrated circuit under test 12 and the device under test 14 formed on the gallium arsenide substrate 10 in a non-contact manner.
This is the point that is used.

FIG. 16 is a cross-sectional view showing a case where a signal electric field emitted from an object to be measured formed on the gallium arsenide substrate 10 is detected by using an electro-optic crystal. The integrated circuit under test 12 or the device under test 1 on the gallium arsenide substrate 10
4 between the signal electrode 52 and the ground electrode 51 around the signal electrode 52 of FIG.
When a high-speed pulse is applied from the light-triggered high-speed signal generator 100 to the signal electrode 52, the operation is performed in response to the high-speed pulse. Therefore, the signal electric fields 58 (FIG.
(FIG. 16B) occurs.

In FIG. 16A, when the electro-optic crystal 60 is placed in the signal electric field 58 in a non-contact manner with the gallium arsenide substrate 10 and the sampling incident light 61 for sampling enters, the polarization state of the sampling reflected light 62 changes. Since the change is caused by the signal electric field 58, if the change in the polarization state is observed as an electric signal by a sampling oscilloscope, the voltage waveform of the signal electrode 52 can be observed in a non-contact manner.

In FIG. 16B, sampling incident light 61 is incident from the back surface of the gallium arsenide substrate 10. Here, the gallium arsenide substrate 10 itself is shown in FIG.
Gallium arsenide substrate 1
Since the plane of polarization of the sampled reflected light 64 changes due to the signal electric field 59 generated during the period 0, if the change in the plane of polarization is observed as an electric signal with a sampling oscilloscope, the voltage waveform of the signal electrode 52 can be measured in a noncontact manner. Can be observed.

In this way, the waveform can be observed by the wideband sampling gate using the electro-optic effect.

FIG. 17 is a block diagram showing a case where an object to be measured is measured by a system using such an electro-optic effect broadband sampling gate. Since the waveforms of the respective parts correspond to those shown in FIG. 14, the description will be made using them.

When a trigger signal for starting the system is applied to the input terminal 20, the signal is converted into a signal having a constant amplitude and pulse width by the trigger generator 21 (FIG. 14).
(A)) is applied to the optical trigger generators 22-1 and 22-2. The light trigger generators 22-1 and 22-2 include laser diodes, respectively, which emit light and are applied to the optical delay circuits 23-1 and 23-2, respectively (FIG. 14B ), (G)).

In the optical delay circuits 23-1 and 23-2,
One of the optical signals delayed by a predetermined amount is the optical trigger 12.
1 (FIG. 14 (c)), the light-triggered high-speed signal generator 10
0 (see FIG. 2), the rising portion thereof is speeded up by the nonlinear transmission line 125 included therein,
4 (d)), the pulse width is narrowed by the waveform shaper 141, and the trailing edge of the pulse is waveform-shaped, and the output terminal 15
9 (FIG. 14 (e)), the integrated circuit under test 1
2 and the device under test 15 which is the device under test 14.
The DUT 15 operates accordingly to operate the signal electric fields 58 and 5.
9 (signal source 231 in FIG.
This is applied to the electro-optic effect wide band sampling gate 203 using the electro-optic effect shown in FIG.

The output of the optical trigger generator 22-2 (FIG. 14)
(G)) in FIG. 14 (h) in the optical delay circuit 23-2.
At the time indicated by the solid line, or at the time indicated by the dashed line variably delayed by a minute time, and applied to the optical pulse compressor 25. The optical pulse compressor 25 compresses the pulse width of the optical pulse in FIG. 14 (h) to several ps and replaces the optical sampling incident light 61 (the optical sampling pulse 111 in FIG. 14 (i) with the optical sampling incident light 61). 16), and the electro-optic effect of the electro-optic crystal 60 of FIG.
The sampling operation is performed by irradiating the back surface of the gallium arsenide substrate 10 of (b). The subsequent operation is the same as that of the system shown in FIG.

As is clear from the above description, the integrated circuit under test 12 and the device under test 14 formed on the gallium arsenide substrate 10 shown in FIGS. After the test is completed, only the integrated circuit under test 12 and the device under test 14 are separated from the optical trigger high-speed signal generator 100 and the wideband sampling gate 200 by dicing or scribing to assure high-speed performance. It can be used as an integrated IC.

[0058]

As is apparent from the above description, by forming a high-speed semiconductor test apparatus on a wafer substrate on which an object to be measured is formed, a high-speed pulse signal which has been impossible so far is used as a signal to be measured. It is possible to introduce it into the measured object. Therefore, since it was possible to observe the signal without signal degradation, it was possible to observe the non-contact nondestructive inspection and the real-time skew characteristics with high accuracy, and the time and budget for the development, design, and production of a dedicated jig or prober were reduced. This has enabled the development of high-speed integrated circuits and labor savings in inspections. Therefore, the effect of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a configuration diagram on a gallium arsenide substrate showing a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of an embodiment of a light-triggered high-speed signal generator which is a component of FIG. 1;

FIG. 3 is a waveform chart showing waveforms at various parts in the configuration shown in FIG. 2;

FIG. 4 is a characteristic diagram showing a diode terminal capacitance characteristic with respect to a reverse voltage of a diode which is a component of FIG. 2;

FIG. 5 is a detailed configuration diagram of a diode capacitance test cell which is a component of FIG. 1;

FIG. 6 is a configuration diagram on a gallium arsenide substrate showing a second embodiment of the present invention.

FIG. 7 is a circuit diagram of a sampling circuit including a wideband sampling gate which is a component of FIG. 6;

FIG. 8 is a detailed block diagram of one embodiment of a wideband sampling gate which is a component of FIG. 6;

FIG. 9 is a cross-sectional view showing the structure of a capacitor for storing a sampled signal through the sampling pulse shown in FIGS. 7 and 8;

FIG. 10 is a system configuration diagram showing one embodiment of a system when measuring the device under test shown in FIG. 6;

FIG. 11 is a waveform chart showing waveforms at various parts of the system shown in FIG. 10;

FIG. 12 is a circuit diagram of a sampling circuit including a wideband photo sampling gate, which is another embodiment of the sampling circuit including the wideband sampling gate shown in FIG. 7;

FIG. 13 is a system configuration diagram showing another embodiment of the system when measuring the device under test shown in FIG. 6 using the sampling circuit shown in FIG. 12;

FIG. 14 is a waveform chart showing waveforms at various parts of the system shown in FIG. 13;

FIG. 15 is a configuration diagram on a gallium arsenide substrate showing a third embodiment of the present invention.

16 is a cross-sectional view showing a state in which a signal electric field is extracted from an object to be measured on the gallium arsenide substrate 10 in FIG. 15 by using an electro-optic crystal.

17 is a system configuration diagram in the case of measuring the device under measurement in FIG. 15 using the electro-optic crystal in FIG. 16;

[Explanation of symbols]

 Reference Signs List 10 gallium arsenide substrate 12 DUT 14 DUT 15 DUT 20 input terminal 21 trigger generator 22 optical trigger generator 23-1, 23-2 optical delay circuit 25 optical pulse compressor 29 signal processing circuit 51 ground Electrode 52 Signal electrode 58, 59 Signal electric field 60 Electro-optic crystal 61 Sampling incident light 62, 64 Sampling reflection light 100 Optical trigger high-speed signal generator 102 Diode capacitance inspection cell 109 Transmission path 111 Optical sampling pulse 121 Optical trigger 122 Photo Conductor 124 Bias terminal 125 Non-linear transmission line 127-1, 127-2, 128 Terminating resistor 129 Center conductor 141 Waveform shaper 144 Bonding wire 147 Terminating resistor 159 Output terminal 160 Ground pattern 200 Wide Range sampling gate 201 Broadband photo sampling gate 202 Diode capacitance test cell 203 Electro-optic effect broadband sampling gate 215 Bias power supply 216 Inductance 217 to 219 Conductor 221 Optical trigger 222 to 224 Photoconductor 225 Nonlinear transmission path 231 Signal source 233 Input terminal 234 Terminating resistor 235,236 Diode 237,238 Sampling pulse 239 Terminating resistor 240-243 Capacitor 245,246 Conductor 248 Dielectric 249 Air bridge 251-256 Resistance 261,262 Amplifier 265 Switch 269 Output terminal D1 , D2 diode

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 21/66 G01R 31/28 QR (72) Inventor Takeshi Kamiya 1-1-11, Miyamae, Suginami-ku, Tokyo (56) Reference Document JP-A-3-102264 (JP, A) JP-A-3-283812 (JP, A) JP-A-4-258773 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/28-31/3193

Claims (14)

(57) [Claims] A bias voltage is applied to a light trigger (1).
21) The conductance is changed by the application of
Photoconductor for outputting a pulse (122)
Receiving the trigger pulse, indicating a long transmission time for a portion having a small amplitude, indicating a short transmission time for a portion having a large amplitude, and speeding up the leading edge of the trigger pulse. Transmission means (125) for outputting the data
Waveform shaping means (141) for shaping the output of the nonlinear transmission means to obtain a high-speed pulse signal; the photo conductor; the nonlinear transmission means; the waveform shaping means; A semiconductor test apparatus using an optical signal including a semiconductor substrate (10) for forming a device under test (12, 14, 15) to be tested by receiving a high-speed pulse signal from the semiconductor device. 2. The semiconductor test apparatus using an optical signal according to claim 1, wherein only the device under test formed on the semiconductor substrate is separately obtained. 3. The semiconductor test apparatus using an optical signal according to claim 1, wherein said optical trigger is applied to said photoconductor via optical delay means (23) for obtaining a delay time. 4. A sampling trigger photoconductor (222) for applying a bias voltage, changing a conductance by applying a sampling light trigger (221), and outputting a sampling trigger pulse.
Receiving the sampling trigger pulse, indicating a long transmission time for a portion having a small amplitude, indicating a short transmission time for a portion having a large amplitude, and a leading edge of the sampling trigger pulse. A non-linear transmission means for sampling (225) for outputting a signal at a high speed, and a sampling pulse for generating a narrow sampling pulse from the output of the non-linear transmission means for sampling whose leading edge is accelerated. Generating means (249), receiving the sampling pulse, sampling the amplitude component of the applied signal under test, and sampling the amplitude component of the signal under test.
Sampling gate means (235, 236, 241, 242) for obtaining a smoothed sampling output
Generating the sampling trigger photoconductor, the sampling nonlinear transmission means, the sampling pulse generating means, the sampling gate means, and a signal to be applied to the sampling gate means. To be tested (12, 14, 1)
5) A semiconductor test apparatus using an optical signal including a semiconductor substrate (10) for forming the above. 5. The semiconductor test apparatus using optical signals according to claim 4, wherein only the device under test formed on the semiconductor substrate is obtained separately. 6. The semiconductor substrate according to claim 1, wherein said signal to be measured is received from said sampling gate means .
5. The semiconductor test apparatus using an optical signal according to claim 4, further comprising a stretcher (265, 243, 262) for holding the amplitude of the sampling output that has become gentler . 7. A light trigger (1
21) The conductance is changed by the application of
Photoconductor for outputting a pulse (122)
Receiving the trigger pulse, indicating a long transmission time for a portion having a small amplitude, indicating a short transmission time for a portion having a large amplitude, and speeding up the leading edge of the trigger pulse. Transmission means (125) for outputting the data
A waveform shaping means (141) for waveform shaping the output of the non-linear transmission means to obtain a high-speed pulse signal; and a biasing voltage applied to the sampling optical trigger (2).
21) Sampling for outputting a trigger pulse for sampling by changing the conductance by applying
Receiving a trigger photoconductor (222), receiving the sampling trigger pulse, indicating a long transmission time for a portion having a small amplitude and a short transmission time for a portion having a large amplitude; A non-linear transmission means for sampling (225) for speeding up and outputting the leading edge of the sampling trigger pulse; A sampling pulse generating means (249) for generating a pulse; receiving the sampling pulse, sampling an amplitude component of the applied signal under measurement, and sampling the amplitude component more slowly than the signal under measurement.
Sampling gate means (235, 236, 241, 242) for obtaining a smoothed sampling output
The photo conductor, the nonlinear transmission unit, the waveform shaping unit, the sampling trigger photo conductor, the sampling nonlinear transmission unit, the sampling pulse generation unit, and the sampling gate Means for receiving a high-speed pulse signal from the waveform shaping means, generating a signal to be measured applied to the sampling gate means, and performing a test under test (12, 14, 1).
5) A semiconductor test apparatus using an optical signal including a semiconductor substrate (10) for forming the above. 8. The semiconductor test apparatus using an optical signal according to claim 7, wherein only the device under test formed on the semiconductor substrate is separately obtained. 9. The application of the optical sampling pulse (111) changes the conductance to sample the amplitude component of the signal under measurement and makes it less gradual than the signal under measurement.
Photo sampling to obtain sampling output
Gate means (201); the photo-sampling gate means; and the device under test (12, 14, 1) which generates the signal-under-test applied to the photo-sampling gate means and undergoes a test.
5) A semiconductor test apparatus using an optical signal including a semiconductor substrate (10) for forming the above. 10. The semiconductor device according to claim 5, wherein said semiconductor substrate is provided with said measurement target from said photo sampling gate means.
A stretcher (265, 243, 26) for holding the amplitude of the sampling output that has become gentler than the constant signal.
10. The semiconductor test device using an optical signal according to claim 9, wherein the device includes 2). 11. An optical delay means (23-2) for delaying an optical trigger signal by said optical sampling pulse applied to said photo sampling gate means.
And an optical pulse compression means (2) for compressing the pulse width of the optical trigger signal delayed by the optical delay means.
11. The semiconductor test apparatus using the optical signal according to claim 9 or 10, which is obtained through the above (5). 12. A photoconductor (12) for receiving a bias voltage and changing a conductance by applying a light trigger (121) to output a trigger pulse.
2) receiving the trigger pulse, indicating a long transmission time for a portion having a small amplitude, a short transmission time for a portion having a large amplitude, and setting a leading edge of the trigger pulse to Nonlinear transmission means (125) for high-speed output
A waveform shaping means (141) for shaping the waveform of the output of the non-linear transmission means to obtain a high-speed pulse signal; and changing the conductance by applying an optical sampling pulse (111) to change the amplitude component of the signal under measurement. Sampling output that is slower than the signal under measurement
Photo sampling gate means for obtaining a force (2
01), the photoconductor, the non-linear transmission means, the waveform shaping means, the photo sampling gate means, and the high-speed pulse signal input from the waveform shaping means.
The device under test (12, 14, 15) that generates the signal under test applied to the sampling gate means and undergoes a test.
And a semiconductor substrate (10) for forming the semiconductor device. 13. The semiconductor device according to claim 12, wherein only the device to be measured formed on the semiconductor substrate is separately obtained.
Semiconductor test equipment using optical signals from 14. A photoconductor (12) for receiving a bias voltage and changing a conductance by applying a light trigger (121) to output a trigger pulse.
2) receiving the trigger pulse, indicating a long transmission time for a portion having a small amplitude, a short transmission time for a portion having a large amplitude, and setting a leading edge of the trigger pulse to Non-linear transmission means (125) for high-speed output
Waveform shaping means (141) for shaping the output of the nonlinear transmission means to obtain a high-speed pulse signal; the photo conductor; the nonlinear transmission means; the waveform shaping means; A semiconductor substrate (10) for forming a device under test (12, 14, 15) to which a high-speed pulse signal is input from the device and a device under test (12, 14, 15);
15) A semiconductor test apparatus using an optical signal including an electro-optic effect sampling means (203) for detecting a signal electric field (58, 59) generated by the electro-optic effect and obtaining a waveform of the signal electric field.