JP2895587B2 - Thermography equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermography apparatus, and in particular, corrects a thermal image of a sample such as a semiconductor integrated circuit with its emissivity distribution to form an accurate temperature distribution image. It relates to a thermographic device that can be obtained.

[Conventional technology]

As shown in FIG. 1, a magnifying lens 3 is attached to an infrared camera 2 attached to a camera stand 1,
The subject 4 is enlarged and the thermal image is taken, and
Thermographic devices that measure temperature by displaying on a CRT are known. In this case, a thermal image in which a minute portion is enlarged can be viewed with an image resolution of about 10 μm, which is almost the same as the infrared observation wavelength of the infrared camera. However, when measuring the temperature distribution to see the heat distribution of the integrated circuit, etc., the measured thermal image reflects the emissivity distribution because the emissivity between the silicon surface of the IC and the metal wiring pattern is significantly different. It is measured as the obtained infrared radiation intensity distribution image, and the true temperature distribution cannot be measured. Therefore, conventionally, the emissivity distribution is obtained, and the observed thermal image is emissivity-corrected by the emissivity distribution to obtain the actual temperature distribution.

 Hereinafter, this emissivity correction will be described.

When the temperature of an object is measured by a thermographic device, as shown in FIG. 6, the infrared radiation emitted from the object and the infrared radiation emitted from the environment and reflected by the object are added to enter the thermographic device. Without correction, the apparent temperature is measured as follows.

R (T ') = εR ( T) + (1-ε) R (T a) , however, epsilon emissivity, T is the temperature of the measurement object, T _a is a temperature of the environment reflection source, general reflection source in the Like the walls of the room,
In the arrangement where the camera and the object are close to each other as shown in FIG. 1, the temperature inside the camera becomes the reflection source temperature. T 'is an apparent temperature to be measured, that is, a temperature indication value of the thermographic device, and R (T) is a wavelength detected by the thermographic device in the amount of infrared radiation radiated from a black body (ε = 1) at the temperature T. In FIG. 7, there is a relationship as shown in FIG. 1-ε is the reflectance of the object. In general, since the emissivity, the object temperature, and the environmental reflection source temperature have a two-dimensional distribution, the above equation is expressed as follows: R (T ′) (x, y) = ε (x, y) R (T) (X, y) + [1-ε (x, y)] R (T _a ) (x, y). That is, ε (x, y), R (T) (x, y), etc. have a two-dimensional distribution. For a general object, 0 ≦ ε (x, y) ≦ 1.

Now, when the object becomes a uniform temperature T _1, the infrared light intensity incident on the infrared _{camera, R (T '1) (} x, y) = ε (x, y) R (T 1) + [1 −ε (x, y)] R (T _a ) (x, y) (1) When the subject is heated to a temperature T ₂ different from the above temperature T ₁ , R (T ′ ₂ ) (x, y) = ε (X, y) R (T ₂ ) + [1-ε (x, y)] R (T _a ) (x, y) (2) From the equation (2)-(1), R (T ′) _{2) (x, y) -R} (T '1) (x, y) ε (x, y) [R (T 2) -R (T 1)] That is, Here, assuming that an unknown temperature distribution when a subject, for example, an IC is energized is T ₀ (x, y), R (T ′ ₀ ) (x, y) = ε (x, y) R (T ₀ ) (X, y) + [1−ε (x, y)] R (T _a ) (x, y) (4) From equation (1), R (T ′ ₀ ) (x, y) y) −R (T ′ ₁ ) (x, y) = ε (x, y) [R (T ₀ ) (x, y) −R (T ₁ )] (5) That is, R (T ₀ ) (X, y) = [R (T ′ ₀ ) (x, y) −R (T ′ ₁ ) (x, y)] / ε (x, y) + R (T ₁ ) (6) or Here, looking at the equation (3), T ′ ₁ (x, y), T ′ ₂
(X, y) is a temperature indication value of each pixel of the thermal image obtained by the thermography device and is known, and therefore, R (′ ₂ ) (x,
y) and R (T ′ ₁ ) (x, y) can be calculated from the temperature-light quantity curve in FIG. T ₂ and T _1, for example, as shown in FIG. 1, since it is measurable with a temperature sensor 6 which is inserted into the metal block 5 which supports the object 4, emissivity profile epsilon (x,
y) can be calculated by equation (3).

Then, looking at equation (6), T ′ ₀ (x, y), T ′ ₁
(X, y) are known in temperature indicator value of each pixel of the resulting thermal image in _{thermography, R (T '0) (} x, y) and _{R (T' 1) (x} , y) is It can be calculated from the temperature-light quantity curve of FIG. Therefore, R (T ₀ ) (x, y) in equation (6)
Can be calculated and T ₀ (x, y) can be known. Expression (7) may be used instead of expression (6).

Meanwhile, to heat or cool the temperature of the object 4 to T ₁ and T _2, for example, as shown in FIG. 1, select the polarity heating / cooling element 7 made of thermo-module using the example Peltier effect What is necessary is just to let a current flow. When using the Peltier effect, the metal block 5 can be heated or cooled depending on the polarity of the current. Then, the temperature of the metal block 5 is detected by the temperature sensor 6 to control the temperature. Since the subject 4 is fixedly supported on the metal block 5, it is heated or cooled to substantially the same temperature as the metal block 5.

Assuming that the temperature-light quantity curve in FIG. 7 is almost linear, the equations (3), (6), and (7) become the following equations (3) ', (6)', and (7) '. It can be simplified as in the equation.

T ₀ (x, y) = [T ′ ₀ (x, y) −T ′ ₁ (x, y)] / ε + T
₁ … (6) ′ or [Problems to be Solved by the Invention] Incidentally, in order to correct the emissivity as described above, the heating or cooling temperatures T ₁ and T ₂ of the subject 4 must be measured. Conventionally, as described above, the emissivity distribution is obtained by measuring the actual temperatures T ₁ and T ₂ with the temperature sensor 6 such as a thermocouple, and the emissivity of a thermal image obtained based on the measured emissivity distribution is corrected. Was determined. It is also a known technique that a part of the subject is painted with a black body paint having an emissivity close to 1 and the sample temperature is determined from the temperature indication value of the thermography device at that point.

However, these measurements and the output of the emissivity-corrected thermal image based on the measurements have conventionally been performed almost manually, which is a time-consuming operation.

Therefore, an object of the present invention is to solve the above-described problems of the conventional technology, and to measure the heating or cooling temperature of a subject by the thermography apparatus itself without actually measuring the temperature of the subject by a temperature sensor, and It is an object of the present invention to provide a thermography apparatus which obtains an emissivity distribution, and obtains a thermal image corrected in emissivity based on the distribution.

[Means for solving the problem]

The thermographic device of the present invention that achieves the above object,
A sample heating stage that has an infrared camera and can set the sample to at least two different temperatures, and selects one point of a black body portion or a high emissivity portion of the sample in the field of view of the infrared camera and sets the temperature at that point. At each time when the measuring means and the sample heating stage are set to two different temperatures, it is determined that the selected temperature is stable, and the temperature of the sample at that point and the thermal image data of the visual field are stored. Means, and means for emissivity correction of a thermal image of an unknown temperature distribution of the sample based on two different temperatures stored in the storage means and thermal image data at those temperatures. Is what you do.

In this case, the field of view of the infrared camera is at least two different.
Means for selectively setting one field of view, and means for storing two selected fields of view and bidirectionally switching from one field of view to the other field of view, wherein the temperature of the sample at the selected point is selected in one field of view. When configured to measure and store, and switch to the other field of view to store thermal image data for that field of view at that temperature, the field of view is expanded even if the sample in the field of view does not have a black body part or a high emissivity part. This is found in the enlarged field of view, at which point the temperature of the sample can be accurately detected and the emissivity map can be calculated accurately. As a result, accurate emissivity correction can be performed.

[Action]

In the present invention, the means for selecting one point of the black body portion or the high emissivity portion of the sample in the field of view of the infrared camera and measuring the temperature at that point and the sample heating stage are set to two different temperatures. At each time, storage means for determining that the temperature at the selected point has become stable and storing the temperature of the sample at that point and thermal image data of the visual field are provided. Temperature measurement is simpler than in the case of detection. Further, since the surface temperature of the sample is measured, the temperature can be measured more accurately than indirectly measured from the temperature of the metal block on which the sample is placed. In addition, two different stable temperature and thermal image data of the sample can be automatically captured and emissivity maps can be calculated quickly and accurately in an automated routine.

〔Example〕

Next, a thermographic apparatus according to the present invention will be described based on embodiments.

Thermography apparatus of the present invention, the object emissivity profile (emissivity maps) the (3) to (3) 'one to the measurement method of temperatures T ₁ and T ₂ when determined based on equation (sample) It is characteristic. That is, instead of measuring the temperature of the subject with a temperature sensor or the like as in the past, an emissivity map is automatically obtained by taking in the thermal image of the infrared camera itself, and the actual temperature distribution of the sample thereafter. Is used for the measurement of

First, as shown in FIG. 1, a thermographic apparatus body is used as in the prior art. That is, a magnifying lens 3 is attached to an infrared camera 2 attached to a camera stand 1, a subject 4 such as an IC is magnified and a thermal image thereof is taken, and is displayed on a CRT. The infrared camera 2 has, for example, a zoom mechanism that can increase or decrease the field of view FOV by changing the scanning angle of the scanning mirror. The subject 4 is heated /
The cooling element 7 is mounted on the integrally fixed metal block 5. This metal block 5, heating / cooling element 7,
The sample moving stage 8 that supports them constitutes a sample heating stage 9 of the thermography apparatus. In the sample heating stage 9, the temperature of the subject 4 mounted on the metal block 5 is set in advance by a temperature sensor 6 inserted into the metal block 5 and a control circuit for controlling a current flowing through the heating / cooling element 7. It is configured to be controllable at high and low temperatures. Further, the infrared camera 2 has two cursors that are superimposed on the field of view and are movable in the Y and X axis directions parallel to the X and Y axes, and the temperature of the thermal image at the intersection of the cursors (cursor cross point) is determined. It is selectively readable. The thermographic apparatus includes a controller (not shown), stores thermal image data captured by the infrared camera 2, monitors temperature data at a cursor crossing point, performs a desired operation based on the data, and performs a sample heating stage 9 operation. Temperature control, switching of the field of view FOV of the infrared camera 2, and the like. When the field of view FOV of the infrared camera 2 is switched by the zoom mechanism of the magnifying lens 3, the adjustment of the zoom mechanism of the magnifying lens 3 can be controlled by the controller.

FIG. 2 shows a flowchart of an example of a processing procedure of the thermography apparatus. However, the steps surrounded by a dotted line in the figure are manually input and executed by an operator, and the automatic processing part of the thermographic apparatus itself of the present invention is only a part surrounded by a solid line. In this case, an IC will be described as an example of the subject (sample) 4. The operator is ST1
, The sample 4 is placed on the metal block 5 on which the heating / cooling element 7 is integrally fixed.
Is input to start heating the sample 4. Usually, since the contrast of the infrared radiation intensity distribution of the sample 4 is weak at normal temperature and a high-contrast thermal image cannot be seen, the camera 2 is focused after heating it in ST2.
Then, in ST3, the visual field for the sample 4 is operated by operating the sample moving stage 8 and operating the zoom function.
Match. Next, in ST4, a point at which the temperatures T ₁ and T ₂ when the temperature of the sample 4 is stabilized is measured by the infrared camera 2 is determined. FIG. 2 shows a case where the operator moves the cursor of the camera 2 on both sides and makes a selection by visual observation, and FIG. 3 shows a case where the selection is made by processing of the apparatus itself instead. Normally, the sample 4 has an area that can be considered as a black body (emissivity ε = 1). When the temperature of the sample 4 is stabilized, the apparent temperature at that point is changed to the sample 4.
Shows the temperature. Therefore, by selecting and monitoring this point with the cursor, the temperatures T ₁ and T ₂ of the sample 4 can be measured. FIG. 2 is based on such a premise, and in ST4, the cursor cross point (CP) is adjusted to such a black body portion. By the way, when the sample 4 is heated uniformly, the black body portion of the sample has the highest apparent temperature.
Therefore, instead of the operator moving the cursor to select the temperature measurement point (CP) of the sample 4 as in ST4 in FIG. 2, the temperature is obtained by the camera 2 as shown as ST ″ in FIG. The apparent maximum temperature point (CP) of the thermal image at the time of uniform heating of the sample 4 can be detected, and this point can be changed to be a subsequent temperature monitoring point. If not, it is effective to apply a black body paint to a part of the sample 4 and measure it.It is ideal that the emissivity ε (CP) of the black body part can be regarded as 1. If it cannot be considered, in equation (1), ε (x, y) = ε (CP)
And when I'll give T _a manually, T _'1 is the temperature indication of thermography device, because it is known, can be calculated sample temperature T ₁ of the corrected emissivity. Similarly, when ε (x, y) = ε (CP) and _Ta are manually given in the equation (2), the emissivity-corrected sample temperature T ₂ can be calculated. these
If the values of T ₁ and T ₂ are used as the temperature value of CP, a more accurate emissivity-corrected image can be created. When the sample temperature measurement point (CP) is determined, the coordinates of this point CP are stored in ST5. Next, in ST6, the thermography device
Monitor temperature. Then, in ST7, it is determined whether or not the temperature at that point has stabilized. Normally, while monitoring the temperature of the CP in a predetermined time interval, when the difference between the previous temperature and the current temperature becomes equal to or less than a predetermined value, it is determined that the temperature has stabilized. Note that other determination methods are also effective. The temperature may be seen the temperature of the CP when the stable temperature of the whole sample 4, and stores the temperature indication value T ₂ in the next ST8. At the same time, the next ST9, the data R (T '2) of the sample of the thermal image _(x, y) stores. Next, in ST10, the computer of the apparatus reverses the current flowing through the heating / cooling element 7 to start cooling the sample 4, and in ST11, monitors the temperature of the position CP previously stored. And ST
At 12, it is determined whether the temperature of the CP has stabilized.
If it is determined that the temperature has stabilized, at ST13, and stores the temperature indication value T _1. At the same time, at the next ST14, the data R (T '1) of the sample of the thermal image _(x, y) stores. Then, in ST15, the computer stores
T ₁ , T ₂ , R (T ′ ₁ ) (x, y), R (T ′ ₂ ) (x, y),
Ε (x, y) was calculated from the temperature-light quantity curve as shown in FIG.
Is stored as an emissivity map. When the above processing is completed, next, an electric current is actually applied to the IC as the sample 4 to generate heat (ST16). Then, the thermal image R (T ′ ₀ ) (x, y) at that time is captured and stored by the camera 2 (ST17), and then, in ST18, the emissivity map ε (x, y) previously stored is stored. , T ₁ , R (T ′ ₁ ) (x, y), and a thermal image R (T ₀₎ representing the actual temperature distribution corrected by the emissivity according to the equation (6) or (6) ′ from the temperature-light quantity curve. ) (X, y) is created. If it is necessary to acquire data by changing the current flowing through the IC (ST24), change the energization conditions (ST25) to ST16,
Repeat steps 17 and 18. At this time, the emissivity map obtained in ST15 is used.

As described above, in the embodiment shown in FIG. 2 or FIG. 3, when the sample 4 is uniformly heated to a low temperature and a high temperature, the temperature indication value of the cursor cross point of the thermal image or the temperature indication of the highest temperature point of the thermal image. Values for the temperature T ₁ and the emissivity distribution
It is an T _2.

By the way, for example, when measuring the temperature by enlarging a very small area of the IC, the measurement field of view (FOV1)
If there is no object with high emissivity in the range, or if it is not possible to apply or stick a black body in this field of view,
A part outside the visual field range of V1 can be recognized as a black body object. That is, as shown in FIG. 5A, normally, when a black body portion exists in the visual field FOV1 whose temperature distribution is to be measured, as shown in FIG. 2 and FIG.
The temperature of the sample 4 can be measured by determining the cursor crossing point or the highest temperature point within the field of view, but as shown in FIG. 5 (b), within the field of view FOV1 where the temperature distribution is to be measured. If there is no black body part in the camera, the field of view of camera 2 is changed by changing its scanning range, etc.
It is effective to determine the cursor crossing point in this visual field range, find the highest temperature point, and identify the temperature at that point as the object temperature. In this case, when the object temperature is stabilized to T ₂ or T _1, switching the field of view FOV1, to perform the capture of the thermal image data at a high temperature and low temperature.
FIG. 4 shows a flowchart of the processing procedure of the thermography apparatus in this case. However, the steps surrounded by a dotted line in the figure are manually input and executed by the operator. ST1 'and ST2' are the same as ST1 and ST2 in FIG. ST
At 3 ', the field of view for the sample 4 is adjusted to the field of view ROV1 for actually obtaining the temperature distribution by operating the sample moving stage 8 and operating the zoom function. Next, in ST4 ', a magnification or a scanning range for obtaining the field of view FOV1 is stored by an operator's button operation of the apparatus or the like. Then
In ST5 ', the field of view is the field of view FOV2 where the black body part exists.
(FIG. 5 (b)). Then, in ST6 ', the operator moves the cursor of the camera 2 on the screen, and matches the cross point (CP) of the cursor to the black body portion. Instead, as shown in ST4 ″ in FIG. 3, the apparent maximum temperature point (CP) of the thermal image of the sample 4 obtained by the camera 2 is detected, and this point is changed to the subsequent temperature monitoring point. When the temperature measurement point (CP) is determined, the coordinates of this point CP and the magnification or scanning range for obtaining the field of view FOV2 are stored in ST7 ', and then the temperature of the CP is monitored in ST8'. , 'at the temperature of the point is determined. temperature whether stable it is determined that stable, next ST10' ST9 stores the temperature indication value T ₂ in.
Then, in ST11 ′, the field of view is switched to FOV1 and the next
'In, the data R (T thermal imaging of the sample in the field of view _{FOV1' ST12 2) (x,} y) stores. Then, ST1
At 3 ', the field of view is switched to FOV2 again, and at ST14', the current flowing through the heating / cooling element 7 is reversed to start cooling the sample 4, and at ST15 ', the previously stored position
Monitor the temperature of the CP. Then, in ST16 ', it is determined whether or not the temperature of the CP has stabilized. If it is determined that the temperature has stabilized, at ST17 ', and stores the temperature indication value T _1. Then, in ST18 ', the field of view is returned to FOV1 again,
'In, the data R (T samples of the thermal image in the field of view _{FOV1' ST19 1) (x,} y) stores. ST20 'after
23 'are the same as ST15 to ST18 in FIG. If it is necessary to perform data acquisition by changing the current flowing through the IC, as described in ST24 and ST25 in FIG. 2, the energization condition may be changed by ST24 'and ST25'.

In the above description, the manual specification of the point at which the temperature of the sample 4 is measured has been described as being performed at the intersection of the cursor (cursor cross point) as shown in FIG. It is needless to say that any index such as a point index and the like may be used. Further, the switching of the field of view of the infrared camera may be performed by changing the scanning angle of the scanning mirror and by configuring the magnifying lens 3 with a zoom lens and adjusting the magnification. Further, the infrared camera is not limited to the mirror scanning type, but may be an IR-CCD camera. The field of view of the IR-CCD camera is switched by a zoom lens. In addition, it will be apparent that various modifications are possible in the thermographic apparatus of the present invention.

〔The invention's effect〕

In the thermographic apparatus according to the present invention, one of the black body portion and the high emissivity portion of the sample in the field of view of the infrared camera is used.
Means for selecting a point and measuring the temperature at that point, and at each time when the sample heating stage is set at two different temperatures, determine that the temperature at the selected point is stable and determine the temperature of the sample at that point. And the storage means for storing the thermal image data of the visual field, so that the temperature measurement is easier as compared with the conventional case where the temperature is detected by a temperature sensor or the like.
Further, since the surface temperature of the sample is measured, the temperature can be measured more accurately than indirectly measured from the temperature of the metal block on which the sample is placed. In addition, two different stable temperature and thermal image data of the sample can be automatically captured and emissivity maps can be calculated quickly and accurately in an automated routine.

Further, there are provided means for selectively setting the field of view of the infrared camera to at least two different fields of view, and means for storing the selected two fields of view and bidirectionally switching from one field of view to the other field of view. By measuring and storing the temperature of the sample at the selected point, switching to the other field of view and storing thermal image data of that field at that temperature, the sample in the field of view has a black body portion or a high emissivity Even if there is no portion, the field of view is expanded and found in the expanded field of view, at which point the temperature of the sample can be accurately detected and the emissivity map can be calculated accurately. As a result, accurate emissivity correction can be performed.

[Brief description of the drawings]

FIG. 1 is a side view of a thermographic apparatus main body according to one embodiment of the present invention, FIG. 2 is a flowchart of an example of a processing procedure of the thermographic apparatus of the present invention, and FIG. 3 is a modification of some steps in FIG. FIG. 4 is a flowchart illustrating another example, FIG. 4 is a flowchart illustrating another example, FIG. 5 is a diagram illustrating a relationship between a black body portion of a sample and a visual field of an infrared camera, and FIG. FIG. 7 is a diagram for explaining the relationship between the temperature of the object and infrared rays emitted from the object and the environment. FIG. 7 is a diagram showing the relationship between the black body temperature and the amount of infrared light. 1 camera stand, 2 infrared camera, 3 magnifying lens, 4 subject, 5 metal block, 6
Temperature sensor, 7 Heating / cooling element, 8 Sample moving stage, 9 Sample heating stage

Continuation of front page (56) References JP-A-62-100623 (JP, A) JP-A-60-205225 (JP, A) JP-A-60-205226 (JP, A) , U) JP 63-6823 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01J 5/48 G01J 5/10 G01J 5/00 B

Claims (2)

(57) [Claims] 1. A sample heating stage which includes an infrared camera and can set a sample to at least two different temperatures, and selects one point of a black body portion or a high emissivity portion of the sample in the field of view of the infrared camera. Means for measuring the temperature at that point with an infrared camera, and at each time when the sample heating stage is set to two different temperatures, it is determined that the temperature at the selected point is stable, Means for storing thermal image data, and means for emissivity correction of a thermal image of an unknown temperature distribution of a sample based on two different temperatures stored in the storage means and thermal image data at those temperatures. And a thermographic apparatus. 2. An infrared camera having at least two different fields of view.
Means for selectively setting one field of view, and means for storing two selected fields of view and bidirectionally switching from one field of view to the other field of view, wherein the temperature of the sample at the selected point is selected in one field of view. 2. The thermographic apparatus according to claim 1, wherein the thermographic apparatus is configured to measure and store the thermal image data of the visual field at the temperature by switching to the other visual field.