JPH01110743A - Device for testing integrated circuit - Google Patents

Abstract

PURPOSE:To obtain a testing device for evaluating the characteristics peculiar to an integrated circuit or a device to the extent of a band of 1THz or thereabouts without being affected by the limitation of a band of input due to the packaging and so on by a method wherein the introduction of an electrical pulse signal into a circuit to be tested on a chip and the measurement of a high-speed electrical pulse signal in the chip are contrived so as to be performed simultaneously using light pulses. CONSTITUTION:A means (a frequency separating and delay circuit) 2, which branches light from one light source 1 into a plurality of multi-light pulses and gives relatively a time delay to each light pulse; means (an irradiation position control part 3 and an objective lens 4) 3 and 4, which irradiate an arbitrary point of a photo-electric conversion circuit (a photoelectric conversion part) 7 on the periphery of an integrated circuit (a chip) 13 using one or a plurality of a light pulse or light pulses of the multi-light pulses as trigger light T; the means 3 and 4, which irradiate an arbitrary point of an electrooptic crystal 18 located at the point of a probe part 5 using one or a plurality of a light pulse or light pulses of the multi-light pulses as sampling light S; the means 4 and 3 and a means (a signal processing part) 11, which receive the reflected light R of the sampling light S to change according to an electric field to be generated by a circuit 14 to be tested; and a means, which enables the probe part 5 to couple with the means 3 and 4 for irradiating the crystal 19 through an electrostrictive element 21 and adjusts in close proximity the distance between the crystal 18 and the circuit 13.

Description

[Detailed Description of the Invention] [Prior Art] In testing integrated circuits or devices, the following methods are used to non-contact test internal nodes of ultra-high-speed integrated circuits:
A method is known in which a narrow optical pulse in a pulse is used as a sampling pulse.

In other words, when an electro-optic crystal is placed near a circuit under test and an extremely short pulse of light is irradiated onto the crystal, the polarization state of the irradiated light changes depending on the magnitude of the electrical signal within the circuit under test. Testing methods that utilize this principle are positioned as having the highest temporal resolution in modern times. For detailed information on these, see, for example, IEEE J,
Quant.

Elec, January 1986, P69-78 J.

This can also be learned from the paper by A. Valdmanis et al.

On the other hand, in conventional tests of integrated circuits or devices, electrical signals from an external signal generator are transmitted via a coaxial cable to a planar circuit consisting of a strip line on which the circuit under test (hereinafter referred to as the circuit under test) is mounted. (hereinafter abbreviated as a mounting board), and drives the circuit under test by applying it from the strip line via a bonding wire or the like,
A common method is to view the measurement results using a similar route.

However, as the pulse signal propagates on a strip line made of a metal conductor such as A1 on a mounting board, as it propagates on the line, for example, an electric pulse with a duration of about 10 picoseconds propagates over a distance of 3 to 5 mm. , there is a problem in that the pulse is spread by about 2 to 3 times due to dispersion. For example, even if a strip line made of superconducting material is used as a circuit, a pulse with a width of 1 to 2 picoseconds will cause 1
It is known that the width increases two to three times with a propagation distance of about 0 mm. Detailed information on these can be found, for example, in J.
Appl, Phys, January 1978, P2O3~31
It can also be obtained from the paper by Kautz, RoL 4.

Additionally, there are problems with impedance mismatching at the connection between the coaxial cable and the strip line on the mounting board and reflection of electrical signals due to propagation mode conversion.

The performance of this connector is also a major issue in determining the bandwidth of conventional test equipment.

As described above, the conventional methods have problems with the method of inputting the test signal to the circuit under test, and the measurement band is dominated by the characteristics of the circuit on the mounting board and the connection part, and it operates at ultra-high speed and high frequency. It has not been possible to directly evaluate the inherent performance of the circuit under test in integrated circuits and devices.

Therefore, in order to test integrated circuits with a time resolution ranging from picoseconds to sub-picoseconds from test signal input to output, an electrical signal generation source must be placed very close to the circuit under test on the integrated circuit chip. It was necessary to supply the test signal to the circuit under test by either generating an electrical signal on-chip.

[Problem that the invention seeks to solve]

Even if there is a means to monitor any internal node of an integrated circuit or device with a time resolution approaching sub-picoseconds, as described above, unless a high-speed electrical signal is used to drive the integrated circuit or device, the integrated circuit cannot be monitored. It is impossible to know the true performance. . That is, in testing techniques for circuits operating at high speed, a device is required that integrates a device that generates a high-speed input signal and supplies it to the circuit under test, and a device that monitors the waveform inside the circuit.

[Means for solving problems]

An object of the present invention is to provide a test apparatus for evaluating characteristics specific to an integrated circuit or a device up to a band of approximately 1 T Hz without being limited by band limitations such as manual implementation. For this purpose, it is a device that simultaneously introduces electrical pulse signals from the circuit under test on the chip and measures high-speed electrical pulse signals into the chip using optical pulses. circuit implementation method,
and integrated technologies such as multi-light pulse irradiation method.

〔Example〕

The present invention will be described in detail according to embodiments and with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically showing an embodiment of the present invention. In the figure, 1 is a light source, 2 is a branching/delay circuit section, 3 is an irradiation position control section, 4 is an objective lens, 5 is a probe section, 6 is a position control section, 7 is a photoelectric conversion section, 8 is a stage, 9 1 is a power supply, 10 is a monitor device, 11 is a signal processing section, and 12 is a display device. Figure 2 shows the probe section 5 of Figure 1,
FIG. 7 is a detailed diagram of the photoelectric conversion section 7. FIG. In the figure, 13 is a chip, 14 is a circuit under test, 15 is a substrate, 16 is a photoelectric conversion circuit, 17 is a bonding wire, 18 is an electro-optic crystal, 19 is a reflective film, 20 is a support, and 21 is an electrostrictive element. It is.

A short optical pulse generated from the light source 1 is converted into a trigger light T1. T2... and sampling light Sl, S2..., which pass through the irradiation position control section 3, the objective lens 4, and the probe section 5, and are projected onto the photoelectric conversion section 7.

Of these, the trigger light T is projected onto the photoelectric conversion circuit 16 of the photoelectric conversion section 7, converted into a constant electric pulse, and inputted to the circuit under test 14 as a pulse signal.

On the other hand, the sampling light S is controlled so as to irradiate any point on the plane of the probe section 5 made of an electro-optic crystal 18 disposed facing the circuit under test 14. At the same time, the irradiation row position and beam spot diameter are confirmed by the monitor device IO. A reflective film 19 made of a dielectric multilayer film is formed on a part or the entire surface of the test circuit side of the probe 5 made of an electro-optic crystal 18, and reflects the sampling light S.
t.

S2 becomes reflected lights R1 and R2 that are reflected according to the electric field condition of the circuit under test 14, and after passing through the objective lens 4 again, they are converted into optical signals in the signal processing section 11 or by a subsequent photoelectric conversion device. It is processed as an electrical signal. The processed results are output to the display device 12. There is a power supply 9 for driving the opto-electric conversion circuit and test circuit 7 . Further, the distance between the probe section 5 and the circuit under test 14 is an important factor that determines the sensitivity, and is controlled precisely and reproducibly by the electrostrictive element 21 of the position control section 6.

In FIG. 2, the circuit under test 14 is located in the center of the board 15.
The photoelectric conversion circuit 1 is placed on a chip 13 having
Combined with 6. An electro-optic crystal 18 is placed facing the circuit under test 14 on the chip 13 and bonded to the tip of the support 20, and the above-mentioned reflective film 19 is applied over the entire bottom surface. The probe section 5 is supported by an electrostrictive element 21,
It is fixed to the objective lens 4 or the irradiation position control section 3.

The minute distance between the probe section 5 and the circuit under test 14 is controlled with submicron resolution by applying a voltage to the electrostrictive element 21.

The principle of sampling is that the refractive index of the crystal is changed by a portion of the signal electric field generated by the circuit under test 14 that has entered the electro-optic crystal 18, and the change is read as a change in the polarization state of the optical pulse. The above-mentioned Val
dmanis et al., and requires a polarizer, analyzer, wave plate, etc. in the path of the pulsed light in FIG. 1, but these are omitted for simplicity. Modern high-speed photodetectors operate in bands of 100 GIIz or higher, and high-speed photoconductive elements are capable of generating sub-picosecond electrical pulses. By using a multi-optical pulse beam, it would also be possible to generate pulse trains with arbitrary widths.

The propagation on the bonding wire is based on P, G, May, etc. (Ul
trafast Phenomena V.

Springer-Verlag P120-122)
According to 11] of 3 picoseconds if it is about 250 μm
It has been experimentally shown that it is possible to transmit electrical pulses without distortion, and it can be used satisfactorily for evaluations up to mid-range GHz.

FIG. 3 is a detailed view of another embodiment of the invention.

In the figure, 22 is a metal wiring. The difference from FIG. 2 is that the circuit under test 14 and the photoelectric conversion circuit 16 are monolithically formed on the same chip 13, and the circuit under test 14
A reflective film 19 is applied to cover only the surface immediately above a certain chip 13, and the trigger light T passes through the area without the reflective film in the periphery and excites the photoelectric conversion circuit 16 around the chip 13. Since the circuit under test 14 and the photoelectric conversion circuit 16 are connected over a short distance on the same plane by a thin film metal wiring 22, the inductance is smaller than in the example shown in FIG. 2, making it possible to achieve an even wider band. Become.

FIG. 4 is a detailed view of another embodiment of the invention.

In the figure, 23 is a solder bump. St or G
A photoelectric conversion circuit 16 is installed in the periphery of the base Fi 15 such as aAs.
is formed. The circuit to be tested 14 with the chip 13 turned upside down is connected to the opto-electrical conversion circuit 16 by solder bumps 23 with the circuit to be tested 14 facing the board 15 at the center of the board 15 . Sampling light S is chip 1
The light is irradiated from the back surface of the chip 3 to the back surface of the wiring of the circuit under test 14 through the chip material, and is processed and detected in the subsequent system as reflected light R reflected by the metal of the circuit under test 14. This method uses solder bumps 23 of about several tens of μm, so
The inductance of the connection part is reduced to about 20 to 50 pH, making it possible to transmit signals over a wider range. Another advantage is that the probe section 5 is not required, but since the transmission effect from the back surface of the chip 13 is utilized, only GaAS, InP, etc. can be used as the chip material.

〔Effect of the invention〕

According to the present invention, it is possible to monitor any node of a circuit under test on a chip with sub-picosecond resolution;
It is now possible to supply high-speed input signals to drive the circuit under test up to THz without reflections or waveform distortion, allowing evaluation of the unique characteristics of integrated circuits or devices regardless of the mounting method. We were able to provide integrated circuit testing equipment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of an embodiment of the present invention, and FIG.
The figure is a detailed view of the probe section 5 and photoelectric conversion section 7 in FIG.
FIG. 3 is a detailed diagram of another embodiment of the invention, and FIG. 4 is a detailed diagram of another embodiment of the invention. 1... Light source 2... Demultiplexing/delay circuit section 3... Irradiation position control section 4... Objective lens 5... Probe section 6... Position control section 7... Photoelectric conversion Section 8... Stage 9... Power supply 10... Monitor device 11... Signal processing section 12... Display device 13... Chip 14... Circuit under test 15... Board 16...・Photoelectric conversion circuit 17...Bonding wire 18...Electro-optic crystal 19...Reflection film 20...Support 21...Electrostrictive element 22...Metal wiring 23...Solder bump patent application Person Nippon Telegraph and Telephone Co., Ltd. agent Patent attorney Hisashi Tama Mushi 5 (2 others) Block diagram of the test device of the present invention Part 1 of the blow of the loose embodiment of the present invention, detailed diagram of the optoelectronic friend selection 3 Figure 4 Detailed diagram of the perspective view of the photoelectric transformation part of the probe part of another embodiment of the present invention.

Claims (4)

[Claims] (1) In an apparatus for non-contact testing of integrated circuits, a means for splitting a single light source into a plurality of multi-light pulses and giving a relative time delay to each light pulse; means for irradiating an arbitrary point of a photoelectric conversion circuit around the integrated circuit using one or more optical pulses as trigger light; and means for irradiating one or more optical pulses of the multi-light pulses as sampling light toward the integrated circuit. means for irradiating an arbitrary point on an electro-optic crystal located at the tip of a probe portion arranged as a probe, and means for receiving reflected light of the sampling light that changes in accordance with an electric field generated by a circuit under test on the integrated circuit. and means for coupling the probe section to a means for irradiating the electro-optic crystal via an electrostrictive element, and adjusting the distance between the electro-optic crystal of the probe section and the integrated circuit in close proximity. An integrated circuit testing device featuring: (2) Testing of an integrated circuit according to claim 1, wherein the probe section has a size that covers the circuit under test, and a reflective film is provided on one side of the electro-optic crystal. Device. (3) The probe portion has a size that covers the entire surface of the photoelectric conversion circuit and the integrated circuit, and the reflective film is provided in an area facing the integrated circuit under test. A testing device for integrated circuits according to item 1. (4) The device comprises means for emitting sampling light from the back side of the integrated circuit where the circuit under test is not located, and obtaining a light pulse reflected from the circuit under test. integrated circuit testing equipment.