Scanning photoinduced current analyzer capable of detecting photoinduced current in nonbiased specimen

• US 5,708,371 A
• Filed: 07/18/1995
• Issued: 01/13/1998
• Est. Priority Date: 03/16/1995
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Koyama, Tohru
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US08/503,567
• Time in Patent Office: 910 Days
• Field of Search: 324/71.3, 324/158.1, 324/73.1, 324/752, 324/765, 324/769, 382/8, 382/162, 382/145, 437/8, 257/48, 257/40, 348/126, 356/400, 356/401
• US Class Current: 324/754.23
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence

Abstract

A sample to be measured having a semiconductor integrated circuit having interconnection lines is set on a scanning photoinduced current analyzer with one end of the interconnection line connected to a ground and the other end connected through a current amplifier to the ground. When a laser beam falls on part having a comparatively low thermal conductivity, such as a part having a void, of the interconnection line while the interconnection line is scanned with the laser beam, temperature distribution in the interconnection line changes at the part. The change in temperature distribution produces spontaneous thermoelectromotive force by the Seebeck effect to induce a current. The current amplifier amplifies the induced current, and then an image date converter converts the amplified current into image information in synchronism with the scanning operation of the laser beam. Since the photoinduced current can be measured without supplying a bias current to the sample to be measured, a current image corresponding to the photoinduced current can be formed to determine the position of a void even if the sample to be measured has a high resistance.

Claims

1. A scanning photoinduced current analyzer capable of detecting photoinduced current induced in a sample to be measured when the sample to be measured is scanned with a focused laser beam, said sample to be measured having opposing contact ends and a resistance of 10 kΩ

or greater, said scanning photoinduced current analyzer comprising;

a laser light source for emitting the laser beam;

scanning means for controlling the laser beam to scan a region specified by a first control signal;

focusing means for focusing the laser beam on the sample to be measured;

control means that provides the first control signal;

connection means for connecting one contact end of said sample to be measured to ground;

current amplifying means connected to the opposing contact end of the sample to be measured for amplifying the current flowing through the sample to be measured and providing an output signal representing the amplified current;

image converting means for converting the output signal of the current amplifying means into image information in synchronism with the scanning operation of the laser beam and for providing the image information; and

image output means for reconstructing an image represented by the image information.

2. The scanning photoinduced current analyzer according to claim 1, further comprising image forming means for forming an image of the reflected light reflected from the sample to be measured and for supplying image forming information to the image converting means,

said image converting means selectively providing the image information and image forming information to the image output means, according to a second control signal from said control means.

3. The scanning photoinduced current analyzer according to claim 1, wherein said connection means comprises a resistor connected in series between said one contact end of the sample to be measured and ground.

4. The scanning photoinduced current analyzer according to claim 1, wherein said connection means comprises a capacitor connected between said one contact end of the sample to be measured and ground.

5. A scanning photoinduced current analyzer for providing a current image of a sample to be measured scanned with a focused laser beam, comprising:

a laser light source for emitting the laser beam;

scanning means for controlling the laser beam to scan a region specified by a first control signal;

focusing means for focusing the laser beam on the sample to be measured;

control means for providing the first control signal;

current amplifying means connected for amplifying the current flowing through the sample to be measured and providing an output signal representing the amplified current;

image converting means for converting the output signal of the current amplifying means into image information in synchronism with the scanning operation of the laser beam and for providing the image information;

image output means for providing said current image from the image information; and

means for enabling the scanning photoinduced current analyzer to obtain said current image without applying voltage or supplying current to the sample to be measured.

6. The scanning photoinduced current analyzer according to claim 5, further comprising image forming means for forming an image of light reflected from the sample to be measured and for supplying image forming information to the image converting means,

said image converting means selectively providing the image information and image forming information to the image output means, according to a second control signal supplied from said control means.

7. The scanning photoinduced current analyzer according to claim 5, wherein

the sample to be measured has opposing contact ends,

one contact end is connected to said current amplifying means, and

said means for enabling the scanning photoinduced current analyzer to obtain said current image without applying voltage or supplying current to the sample to be measured comprises a resistor connected between ground and the other contact end.

8. The scanning photoinduced current analyzer according to claim 5, wherein

the sample to be measured has opposing contact ends,

one contact end is connected to said current amplifying means, and

said means for enabling the scanning photoinduced current analyzer to obtain said current image without applying voltage or supplying current to the sample to be measured comprises a capacitor connected between ground and the other contact end.