JPH05312742A - Material judging apparatus - Google Patents

Abstract

PURPOSE:To easily perform a material judgment regarding the internal state, the material quality, the film-layer state and the like of an object under test and to increase the judgment accuracy of its detection. CONSTITUTION:An object 7 under test is irradiated with a laser beam by using a laser oscillator 1 which is operated by a pulse power supply 8. A beam of infrared reflected light which is generated by a rise in the temperature of an irradiation point on the object 7 under test is detected by means of a detector 4. The time which is elapsed until infrared rays in a prescribed quantity are detected from the irradiation of the laser is detected by using a timer circuit 10. A signal is input to an operation and processing device 12; it is operated and processed. A result is compared with known data in memories 13 and processed. A judged output is displayed 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material judging device.

[0002]

2. Description of the Related Art Conventionally, an object to be measured is irradiated with laser light,
It is known that the reflected light is detected using a CCD or the like to determine the material. In this case, the internal state, material, film layer state, etc. can be detected even if the surface state of the DUT can be detected. Could not be detected and judged. Further, if the reflection surface of the object to be measured is inclined or uneven, secondary reflection is repeatedly diffused, so that the detection signal contains many errors.
It was not possible to make an accurate measurement.

[0003]

According to the present invention, it is possible to easily determine the material such as the internal condition, material and film layer condition of the object to be measured.
In addition, it is an object of the present invention to be able to make the detection determination accuracy accurate.

[0004]

A laser irradiation device for irradiating an object to be measured with a laser beam and an infrared detection device for detecting infrared rays reflected from the object to be measured are provided, and a material is determined by an infrared detection signal. It is characterized by having done. Further, a laser irradiation device for irradiating the object to be measured with a laser beam, an infrared detection device for detecting infrared rays reflected from the object to be measured, and an arithmetic processing device for comparing the detection signal of the detection device with known data are provided. It is characterized by consisting of.

[0005]

As described above, according to the present invention, the material is judged by detecting the infrared reflected light having a wavelength different from the irradiation light, so that the internal condition, material, film layer condition, etc. of the object to be measured can be easily detected and judged. .. Further, there is an effect that the accuracy of detection and determination can be made accurate.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment of the drawings. In FIG. 1, 1 is a laser oscillator, 2 is a laser beam focusing lens, 3 is a reflected light receiving lens, 4 is an infrared detector, and these irradiation system and light receiving system are the supporting heads 5.
Is provided at the end of the head 5, and a contact needle 6 for distance measurement is placed at the tip of the head 5 to face the object to be measured 7. 8 is a laser oscillator 1
Pulse power source, 9 is a discriminator for discriminating the signal of the detector 4, 10 is a timer circuit for obtaining a time signal between the signal of the power source 8 and the signal of the detector 4, 11 is an interface,
Through this, a time signal is input to the arithmetic processing unit CPU12, the CPU12 performs arithmetic processing by this signal, reads known data from the ROM and RAM memory 13, performs arithmetic processing on the known data, and displays it on the display unit 14. 15
Is a preset device of the CPU 12.

The laser oscillator 1 is a semiconductor He--Ne.
A laser or the like is used, and the infrared detector 4 uses a sensor capable of selectively detecting infrared rays. Detection wavelength range of the sensor is _P b TiO _{3 1~15μm,} at _{P b} S 0.8 to 3
μm, and LiTiO ₃ is 1 to 15 μm. Of course, an infrared filter can be provided, and Si is 0.6 to 1.2.
μm, Ge 0.6-1.5 μm, InAs 0.8-
3.6 μm, 1 to 5 μm for InSnTe, etc. are used.

In the above, the oscillator 1 is driven by the pulse power source 8, and the oscillating pulse laser is focused by the lens 2 to irradiate one measurement point of the DUT 7. The irradiation point rapidly rises in temperature by laser irradiation and emits infrared rays. The relationship between the temperature rise ∂T / ∂t at the irradiation point and the temperature gradient change rate is expressed by the following equation.

[0009]

[Equation 1]

The specific heat C is expressed by the following equation.

[0011]

[Equation 2]

Temperature rise ΔT t seconds after laser irradiation
Is expressed by the following equation.

[0013]

[Equation 3]

Here, tc = l ² / π ² t _1/2 , 1 represents the thickness, and t _1/2 represents half the time to reach Tmax. Laplace transform the above equation to ln (t
^{When [} alpha] is calculated from -l < ² > / 4 [alpha] by linear regression of [ ^{1/4. [} Delta] T), it is expressed by the following equation by the logarithmic method.

[0015]

[Equation 4]

ΔT at the time of 1/2 hour is expressed by the following equation.

[0017]

[Equation 5]

The material can be judged from the change of α in various materials, and the film thickness 1 can be judged and detected.
When the semiconductor laser 1 is oscillated by the pulse power source 8 to irradiate the DUT 7 having a thickness of 1 with laser, the timer circuit 10 is reset by the signal from the pulse power source 8 and the DUT 7 is measured.
The laser irradiation point in the
_The infrared sensor 4 detects the required infrared ray after _½ , and this is detected by the infrared sensor 4. The detection signal is discriminated by the discriminator 9, and when a predetermined signal output is obtained, the signal is added to the timer circuit 10 and set. The time signal t _1/2 of the timer circuit 10 is input to the CPU 12 to calculate the thermal diffusivity α, and by comparing this with known data in the memory 13, the material of the DUT 14 can be determined. .. or,
It is possible to measure the thickness 1 of the object 7 to be measured whose material is clear (α is determined) by detecting the time t _1/2 .

For example, when the object to be measured is a gold-platinum alloy, a laser beam having a pulse width of about 10 to 100 μS and a power of about 0.1 W to 50 mw is narrowed to a beam diameter of 15 μφ, and the power density is 10 ³ to 10 ⁴ W. / Cm ² beam irradiation and heating temperature Tmax at the irradiation point is 200 to 500 ° C.
Measure in degrees. The use of InS _b to the detection sensor, which is the infrared detection of 3~5μm zone has a peak sensitivity near a wavelength 5 [mu] m, and outputs a determination signal based on the infrared intensity which corresponds to the 200 to 500 ° C.. That is, the delay time from the irradiation of the pulse beam until the detection sensor detects the infrared ray having the predetermined value is measured and used as the determination signal.
In the case of plating, etc., the pulse width of the irradiation laser is 1 to 1
Since a pulse of about 0 ms is used, a plurality of the above pulses are emitted. In addition to metals and alloys, organic substances can be determined for the object to be measured, and the power density of this irradiation beam is about 10 ³ to 10 ⁴ W / cm ² , and in the case of ceramics, 10 ⁵ to 10 ⁸ W / cm. Uses about ² energy. Other judgments such as composite materials and graded materials can be made in the same manner.

[0020]

As described above, according to the present invention, a laser irradiation device irradiates an object to be measured with a minute spot, and infrared rays reflected from the irradiation point are detected by an infrared detector to judge a material. That is, since the thermal diffusivity peculiar to the material is inversely proportional to the time from the laser irradiation until the infrared rays are generated by the heating of the irradiation point, the thermal diffusivity can be calculated by measuring this delay time. The material can be easily determined by comparing this with known data. In addition, the material can be used not only to judge the material but also to detect and measure the internal state, film layer state, and film thickness, and because it detects the infrared rays generated from within the material, it is not significantly affected by diffused reflection due to the surface state of the measured object. Can be measured accurately.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

 1 Laser Oscillator 2, 3 Lens 4 Infrared Detector 7 DUT 8 Pulse Power Supply 9 Discriminator 10 Timer Circuit 11 I / O 12 CPU 13 Memory 14 Display 15 Preset Device

Claims (2)

[Claims] 1. A laser irradiation device for irradiating a measured object with a laser beam and an infrared detection device for detecting infrared rays reflected from the measured object are provided, and the material is determined by an infrared detection signal. Material determination device. 2. A laser irradiation device for irradiating an object to be measured with a laser beam, an infrared detection device for detecting infrared rays reflected from the object to be measured, and arithmetic processing for comparing and comparing a detection signal of the detection device with known data. A material determination device comprising: a device.