JPS62293628A - Semiconductor inspection device - Google Patents

Abstract

PURPOSE:To enable evaluation, analysis, and inspection of a semiconductor device to be realized with non-contact and high-speed operation in a unit of its memory element, by controlling operations of a laser scanning means, a test signal generation means, a photoexcitation current inspecting means, respectively by using a timing means. CONSTITUTION:A power source means 40 supplies electric power to a semiconductor device 10. A test signal generation means 60 impresses a test signal containing an address signal on an input terminal of the device 10. A laser means 20 synchronizes with the address signal and radiates laser light selectively to the prescribed part of a memory element directed by the address signal. In a photo-excitation current measuring means 60, photo-excitation current appearing on the outside terminal of the device 10,due to carriers excited by light of laser radiation inside the device 10, is measured. A timing means 70 controls timing of respective means 20, 60, and 50. A memory means 80 memorizes and holds the data measured by the means 50. Thus, evaluation, analysis, and inspection of the device 10 can be realized with non-contact and highspeed operation in terms of memory element.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention Industrial Application Field The present invention relates to a semiconductor inspection device having a memory element such as a memo IJ-LSI or a liquid crystal driving LSI formed in a liquid crystal display panel. The present invention provides an inspection means capable of carrying out a non-contact, efficient and detailed inspection.

Conventional technology In order to analyze which location of a semiconductor integrated circuit (hereinafter referred to as LSI) is malfunctioning or which location has a characteristic problem, a metal probe is inserted into the metal wiring pattern inside the LSI. The electrical condition of the LSI internal circuit is measured by mechanically contacting the LSI.

The problem that the invention aims to solve The above conventional method has the following problems.

(1) As the internal elements and internal wiring of LSIs have become finer, it has become impossible to accurately contact the intended wiring pattern.

(2) Wiring patterns are likely to be damaged due to mechanical contact.

(3) When measuring multiple locations, the processing speed cannot be improved because the method is mechanical.

Means for Solving the Problems The present invention has been made in view of the above-mentioned problems, and is based on the invention, in which a finely focused laser beam is applied to a memory element inside a semiconductor device that is selected by an address signal input from the outside. is irradiated via a laser scanning means, and a photoexcitation current flowing in accordance with the electrical state of the memory element irradiated with the laser is read from an external terminal of the semiconductor device, thereby making it possible to determine the quality of the memory element.

That is, in the present invention, a plurality of memory elements are arranged in an X-Y matrix, and a predetermined operation is performed by externally writing or reading data into or from the memory elements selected by an address signal input from the outside. a power supply means for supplying power to the semiconductor device; a test signal generating means for applying a test signal including the address signal to an input terminal of the semiconductor device; A laser means that selectively irradiates a predetermined portion of a storage element designated by a signal with laser light, and a photoexcited current appearing at an external terminal of the semiconductor device by a carrier that is photoexcited inside the semiconductor device by the laser irradiation is measured. A photoexcitation current measuring means, a timing means for controlling the timing of the laser means, the test signal generation means, and the photoexcitation current measurement means, and a memory means for storing and storing data measured by the photoexcitation current detection means. This is a semiconductor inspection device characterized by the following.

More preferably, the present invention includes a display device that modulates the stored measurement data in brightness and displays an image corresponding to the arrangement position of the storage element selectively irradiated with laser,
A memory element having a determination means for comparing the brightness-modulated image data with reference data, calculating the difference, and determining that the brightness difference is a certain value or more as a failure, and the data difference is more than the certain value. The address of the department will be displayed.

Effect: By the above means, it is possible to irradiate a semiconductor memory element located anywhere on a substrate with a laser beam, and therefore, a large area formed on a miniaturized and highly integrated liquid crystal display panel can be irradiated with a laser beam in a non-contact manner. It becomes possible to evaluate and analyze the electrical state of functional elements such as semiconductor devices. Furthermore, since the analysis is performed using an optical method, processing speed can be improved.

Embodiment An embodiment of the semiconductor inspection apparatus according to the present invention is shown in FIGS.
This will be explained using FIG.

FIG. 1 shows a configuration diagram of a semiconductor testing apparatus according to an embodiment of the present invention, and FIG. 6 shows a timing chart when testing a semiconductor device.

' In FIG. 1, the surface of a semiconductor device (LSI) 1o is irradiated with laser light by a laser means 2o. Here, the laser means 2o is composed of a He-Ne laser light source 21, an optical lens 22, an optical chopper 23, a laser scanning means 30, an objective lens 25, and the like. The laser light output from the laser light source 21 is transmitted to the optical chopper 2.
3 and then inputted into the laser scanning means 3Q.

In this embodiment, the optical chopper 23 is used to adjust the light amount and to
A, O, M (Acous to -○p)
tic Modulator).

The laser scanning means 3o is for scanning the laser beam 1 on the surface of the semiconductor device in the X and Y directions, and is composed of a galver mirror, a polygon mirror, etc., and is electrically controlled. The laser beam scanned by the laser scanning means is finely focused by the objective lens 26 and irradiated onto the surface of the semiconductor device 1o.

FIG. 2 shows a configuration diagram of the laser scanning means 3o.

The X address signal and Y address signal output from the test signal generating means 60 to the semiconductor device are simultaneously applied to the laser scanning means 3o. The X address signal is D
/A converter 31X, where it is converted into an analog signal corresponding to the X address signal, and then sent to amplifier 3.
It is amplified by 2X and becomes the input to the galver mirror 33X. Similarly, the Y address signal is also sent to the D/A converter 31Y,
The signal is input to a galver mirror 33Y via an amplifier 32Y. By injecting the laser beam into the galver mirror 33X133Y, it becomes possible to irradiate the surface of the semiconductor device designated by the XY address signal, that is, the surface of any memory element selected by the address signal.

In FIG. 1, the power necessary for the semiconductor device 1o is supplied by a power source 4o, and the power source 4o is supplied to the power terminal of the semiconductor device via a photoexcitation current detection means 50. or,
Signal input to the semiconductor device is supplied by the test signal generating means eO, allowing the semiconductor device 10 to operate as desired. By inputting this signal, a desired operation is performed by electrically selecting a memory element in a semiconductor device in which a plurality of memory elements are arranged in rows and columns in the X-Y direction.

At this time, the semiconductor inspection apparatus of the present invention irradiates the selected memory element with a laser. By this laser irradiation, a photoexcitation current corresponding to the electrical state of the storage element is read by the photoexcitation current detection means 5°. For this reason, the operation of the laser scanning means 3o, the operation of the test signal generating means 60, and the optical excitation current detecting means 5o must operate in synchronization. In the present invention, a timing means 7o is provided to control these timings. This timing means performs a series of controls including operation control of the semiconductor device, laser irradiation timing, and detection of photoexcitation current. Since this operation is generally performed for each memory element arranged in a matrix on a two-dimensional plane of a semiconductor device, a plurality of photoexcitation current data are obtained, so in this embodiment, these data are sequentially stored in the memory means 80. save. The memorized and saved data is used for image display or quality determination.

Inspection of the electrical state of a semiconductor device by laser irradiation utilizes the fact that the flow of electrons and holes that are photoexcited inside the semiconductor varies depending on the electrical state of the semiconductor device.

For example, the case where the source region of the MOS-FET shown in FIG. 3a is irradiated with a laser will be explained.

First, when the gate terminal voltage is oV, that is, the FET is OFF, the holes + mainly flow to the p + G N D terminal, and the electrons - mainly flow to the n + source terminal. get together.

Therefore, as shown in FIG. 3, electrons - and holes + are combined via the external wiring, and a circulating current IC flows, so that there is no increase in current at the power supply terminal.

On the other hand, when the gate terminal voltage is 2V, that is, the FET is ON, among the electrons -1 holes +n photoexcited near the n+ source region, the holes + mainly flow to the p + G N D terminal, and the electrons - are ○N flows through the state channel to the n+ drain terminal. Therefore, an increase in the current of io is observed at the power supply terminal.

By measuring the current flowing to the external terminal in this way,
It is possible to determine whether the FET is ON/FF or pass/fail.

Next, the operating state of the semiconductor inspection apparatus of this embodiment is shown in FIGS. 4 and 6.
This will be explained using figures.

Figure 4 shows a liquid crystal drive LSI used in liquid crystal display panels.
FIG. MOS-FE consisting of a thin film transistor such as amorphous silicon on a transparent glass substrate
Storage elements consisting of T (Q and capacitance (q) are arranged in matrix in the X and Y directions, and the capacitance of the plurality of storage elements selected by the Y address signal line corresponds to the potential on the data line. Electric charge is charged.

As mentioned above, this semiconductor device is an LS for driving a liquid crystal display panel.
After performing a light distribution process on the surface of an LSI formed on a glass substrate, a liquid crystal material is placed between it and the opposing glass substrate. In the actual operating state of the liquid crystal display panel, the υ character,
Graphic or image display can be performed.

When testing the characteristics of this LSI using the semiconductor testing apparatus of this embodiment, each MO3-F of the memory element shown in FIG.
ET part, Po, P 1-・----P 1o.

Pll... is sequentially irradiated with laser light. At this time, the Y address signal and write signal shown in FIG. 6 are supplied to the Y address signal line and data input line from the aforementioned test signal input means.

During the period to, the laser scanning means 30 operates to irradiate a laser beam to the position po using the Y address signal. In this embodiment, the X address signal of the test signal input means is not input to the semiconductor device, but only to the laser scanning means.

First, while the Y address signal is at a high level, the MOS-FETs of the corresponding plurality of storage elements are turned on, and during this period, the data input signal is applied and the capacitance of each storage element is charged. Next, the Y address signal becomes low, and at the same time, the data input signal also becomes low. Next, a sampling pulse S1 for current measurement is given to the photoexcitation current detection means 60, and the current is measured when the MOS-FET is OFF and the laser is not irradiated. Then the laser pulse turns on
Then, the point po is irradiated with laser light, and the current during laser irradiation when the MOS-FET is OFF is measured by the sampling pulse S2.

Next, the Y address signal becomes high level and the data input signal also becomes high. After the capacitance is charged up again, current measurement is performed using the sampling pulse S3. Next, the laser is turned on and current measurement is performed in S4. Here, the difference between the currents due to 82 and Sl is the photoexcitation current when the FET is OFF, and the difference between the currents due to S4 and 33 is the photoexcitation current when the FET is ON.

During the next [tl period, a similar operation is performed for Pl, and this operation is sequentially repeated.

As described above, the sequentially measured photoexcitation currents are stored and stored in the memory means.

The data stored in the memory means is modulated in brightness according to the magnitude of the photoexcitation current at the laser irradiation position, and if an image element is used, the amount of current can be evaluated visually and in accordance with the location where the memory element is placed.

Here, if there is a defect in the memory element, the photoexcitation current will be different from that of a normal memory element, so it is possible to limit the faulty memory element.

Further, the brightness-modulated image data may be compared with reference image data, and the difference in brightness may be displayed.

Also, if only the parts where this luminance difference is above a certain value are displayed,
More effective analysis becomes possible.

Furthermore, effective information can be provided by calculating and determining the physical positions in a matrix of memory elements in which the luminance difference is greater than or equal to a certain value.

It is also effective to count the number of functional elements whose luminance difference is greater than a certain value.

Effects of the Invention As described above, according to the present invention, evaluation, analysis, and inspection of each memory element of a semiconductor device in which a plurality of memory elements are arranged in rows and columns in the X and Y directions can be realized in a non-contact manner and at high speed. can.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a semiconductor inspection device of the present invention, FIG. 2 is a schematic configuration diagram of a laser scanning means of the same device,
FIG. 3 is an explanatory diagram of the flow of electrons and holes, FIG. 4 is a configuration diagram of the semiconductor device, and FIG. 6 is a timing chart during inspection of the semiconductor device. 10... Semiconductor device, 2o... Laser means, 30... Laser scanning means, 4Q...
...Power supply means, 50...Photoexcitation current detection means, 6Q...Test signal generation means, 7o...
...timing means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
illustration gate terminal laser light laser light

Claims (4)

[Claims] (1) A semiconductor device in which a plurality of memory elements are arranged in an X-Y matrix and performs a predetermined operation by externally writing or reading data to or from the memory elements selected by an address signal input from the outside. a power supply means for supplying power to the semiconductor device; a test signal generation means for applying a test signal including the address signal to an input terminal of the semiconductor device; a laser means for selectively irradiating a predetermined portion of a storage element with laser light, and a photoexcitation current measurement for measuring a photoexcitation current appearing at an external terminal of the semiconductor device by a carrier that is photoexcited inside the semiconductor device by the laser irradiation. means, timing means for controlling the timing of the laser means, the test signal generating means, and the photoexcitation current measuring means, and a memory means for storing and storing data measured by the photoexcitation current detection means. Semiconductor inspection equipment. (2) Semiconductor inspection according to claim 1, comprising a display device that modulates the brightness of stored measurement data and displays an image corresponding to the arrangement position of the storage element selectively irradiated with laser. Device. (3) Claim 1, further comprising a determining means for comparing the brightness-modulated image data with reference data, calculating the difference, and determining that the brightness difference is a certain value or more as a failure. semiconductor inspection equipment. (4) The semiconductor inspection device according to claim 1, which displays addresses of memory element portions where the data difference is greater than or equal to a certain value.