JPH07311168A - Internal heat analyzer - Google Patents

Abstract

PURPOSE:To provide an internal heat analyzer for detecting the heating point of in the fine internal circuit of a semiconductor IC. CONSTITUTION:A pattern image and a heating image are picked up by means of a single infrared camera 40 and a synthesized by a synthesizing means 70. In the synthesized image, an image representative of the heating points of a heating image is superposed on the circuit pattern of the pattern image. The synthesized image is presented on a display means 80 and an operator can specifies a heating point in a semiconductor IC easily by observing the synthesized image visually.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzing device for analyzing a heat generating portion such as an IC circuit, and more particularly to an analyzing device capable of accurately detecting a heat generating defective portion due to an abnormal current such as a short circuit of a semiconductor element circuit pattern.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field,
The thing of Unexamined-Japanese-Patent No. 2-198347 is known.
The configuration of the conventional internal heat generation analysis device described in this document is shown in the block diagram of FIG. As shown in the figure, a semiconductor element 201, which is an object to be measured, is placed on the sample table 200, and a visible light 203 from an illumination light source 202 or a laser beam 205 from a laser generator 204 is placed on the circuit surface of the semiconductor element 201. Is selectively irradiated. A reflection image of the visible light 203 emitted from the illumination light source 202 is captured by the visible camera 206, and an infrared image of the surface of the semiconductor element 201 heated by the irradiation of the laser light 205 from the laser generator 204 is captured by the infrared camera 207. To be done. The two images thus captured are provided to the image composition circuit 208, and a composite image in which the temperature information image is superimposed on the visible light image of the circuit pattern is created. This composite image is displayed on the display device 209, and the heat generation portion in the circuit pattern can be identified by the naked eye.

[0003]

However, in the conventional internal heat generation analysis apparatus, the two images provided to the image synthesis circuit 208 are captured by two different cameras 206 and 207, so that the two images are highly accurate. It was extremely difficult to synthesize it according to. Therefore, the semiconductor element 20
When the circuit pattern of No. 1 is fine, it is difficult to identify the heat generation point, which is a problem.

It is an object of the present invention to solve such a problem and to provide an internal heat generation analysis device capable of specifying a heat generation point of a fine circuit pattern.

[0005]

In order to solve the above-mentioned problems, a first internal heat generation analysis apparatus of the present invention comprises: (a) a mounting table on which an object to be measured having a circuit pattern surface exposed is mounted;
(B) heating means for heating the object to be measured placed on the mounting table; (c) infrared imaging means for imaging the circuit pattern of the object to be measured mounted on the mounting table; and (d) for the mounting table. A power supply means for applying a bias voltage to the circuit of the mounted object to be measured, and (e) a heating means, an infrared imaging means and a power supply means are controlled to control the circuit pattern and the heating of the object to be measured heated by the heating means. Image pickup control means for picking up a pattern image and a heat generation image by picking up an image of the circuit pattern of the DUT to which the bias voltage is applied by the power source means without heating by the means, and (f) the image pickup control means. It is provided with a synthesizing unit that synthesizes the obtained pattern image and the heat generation image to create a synthetic image, and (g) a display unit that displays the synthetic image synthesized by the synthesizing unit.

The second internal heat generation analysis apparatus of the present invention is (a) a mounting table on which a measured object whose circuit pattern surface is exposed is mounted, and (b) an measured object mounted on the mounting table. A heating means for heating the device, (c) infrared imaging means for imaging the circuit pattern of the object to be measured placed on the mounting table, and (d) a bias voltage to the circuit of the object to be measured mounted on the mounting table. By controlling the power source means to be applied, and (e) the heating means, the infrared imaging means and the power source means, the circuit pattern of the DUT heated by the heating means and the bias voltage by the power source means are not heated by the heating means. The infrared imaging means images the circuit pattern of the DUT to which the voltage is not applied and the circuit pattern of the DUT to which the heating means does not heat and the bias voltage is applied by the power supply means. 1 Fever image, an imaging control means for obtaining the second heating the image, the second obtained by (f) imaging means
A synthesizing means for creating a synthetic image by synthesizing the third thermal image and the pattern image by subtracting the first thermal image for each pixel from the thermal image of
(G) display means for displaying the combined image combined by the combining means.

[0007]

According to the first internal heat generation analysis apparatus of the present invention, the image pickup control means controls the heating means, the infrared ray image pickup means and the power source means, and the same infrared ray image pickup means picks up the pattern image and the heat ray image of the circuit. It Here, at the time of capturing the pattern image, the object to be measured is heated to increase the amount of infrared rays radiated from the circuit surface, so that the infrared image capturing means can capture the pattern image. Further, at the time of capturing the heat generation image, the bias voltage is applied without heating the object to be measured. For this reason, infrared rays are radiated from the heat generation portion of the circuit, and an image of this infrared radiation area (that is, an image of the heat generation portion) is captured.

The pattern image and the heat generation image thus taken are given to the synthesizing means, and the image showing the heat generation portion of the heat generation image is superimposed on the circuit pattern of the pattern image to form a synthesis image. Since the composite image is displayed on the display means,
The operator can visually observe this composite image, and can easily identify the heat generation point on the circuit pattern.

Further, the second internal heat generation analysis device of the present invention is different from the image pickup control means of the first internal heat generation analysis device described above in the synthesis means. The pattern control image and two types of heat generation images (first heat generation image and second heat generation image) are captured by the imaging control means of the second internal heat generation analysis device. The two types of heat-generating images are captured without being heated, but the bias voltage is not applied when capturing the first heat-generating image.
A bias voltage is applied at the time of capturing the second heat generation image. Therefore, the image of the heat generation portion and the background noise are captured in the second heat generation image, but only the background noise is captured in the first heat generation image. Then, the background noise of the second heat-generating image is removed by subtracting the first heat-generating image from the second heat-generating image for each pixel by the synthesizing unit. Further, in the synthesizing means, the image from which noise is removed (third exothermic image) and the pattern image are synthesized,
A composite image is created.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the configuration of the internal heat generation analysis apparatus according to this embodiment. As shown in the figure, the internal heat generation analysis apparatus of the present embodiment has a sample chuck 2 for mounting the IC sample 10 having the circuit pattern surface 10a exposed by removing the mold by a chemical method or the like.
0, a ceramic heater 30 that is built in the upper surface of the sample chuck 20 and heats the IC sample 10, and a sample heater that is disposed in the upper space of the sample chuck 20.
And an infrared camera 40 for picking up an image of the circuit pattern of the IC sample 10 mounted on. Further, a bias power supply device 50 that applies a bias voltage to the circuit of the IC sample 10, a heating power supply device 60 that supplies power to the ceramic heater 30, and an image processing device that processes an image captured by the infrared camera 40. 70 and a monitor 80 for displaying the image output from the image processing device 70.
Here, the IC sample 10, the sample chuck 20, the infrared camera 40, etc. are housed in a heat shield box 90,
Infrared rays from the outside are blocked by this heat shield box 90. Therefore, erroneous measurement of heat generation analysis of the IC sample 10 can be prevented.

Next, details of each component device of this embodiment will be described. First, the sample chuck 20 is an IC that has undergone shaving to embed the ceramic heater 30.
It includes a socket 21, a printed circuit board 22 on which the IC socket 21 is mounted, and a take-out pin 23 attached to the printed circuit board 22 and electrically connected to each lead pin (foot) of the IC sample 10. Therefore, the bias voltage from the bias power supply device 50 is applied to the IC sample 10 via the extraction pin 23. The sample chuck 20 is fixed on the upper surface of the XYZ stage 100. The XYZ stage 100 is a three-axis fine movement stage in which an XY axis stage for slightly moving a measurement point to enter the camera visual field and a Z axis stage for focusing are integrated. Fine position adjustment is possible.

The ceramic heater 30 is the IC sample 1
It is arranged between the back surface of the sample chuck 20 and the top surface of the sample chuck 20 so that the IC sample 10 can be easily removed. Further, the ceramic heater 30 is processed into a plate shape so that the entire IC sample 10 is uniformly heated with a relatively small electric power. Depending on the size of the IC sample 10, various shapes other than the plate shape are used.
Further, a platinum temperature sensor 31 is provided at one end of the ceramic heater 30, and temperature adjustment is performed so as to maintain an optimum temperature.

In the infrared camera 40, the resolution is emphasized.
An infrared CCD camera having 12 × 512 elements and having a sensitivity in a band of 3 to 5 μm is used. Therefore, another two-dimensional infrared sensor may be used if the resolution is not important.
Further, an infrared lens 41 is attached to the infrared camera 40, so that the circuit pattern of the IC sample 10 can be enlarged and imaged. Here, the infrared lens 41 is preferably a lens having a high transmittance in the infrared wavelength range and a large NA (Numerical Aperture: lens aperture ratio). In this embodiment, a germanium lens with an F number of 1.2 is used.
Also, the optical magnification is 1, 4, or 1, depending on the type of the object to be measured.
It is possible to select from three types of 5 × lenses.

Although a single DC power supply is used for the bias power supply device 50, a plurality of DC output power supplies and a semiconductor parameter analyzer may be used depending on the IC sample 10.

The heating power supply device 60 includes a platinum temperature sensor 3
1 is a power supply device that controls the applied temperature by changing the current flowing through the ceramic heater 30, and can be turned on (turned on) / off (cut off) by remote control from the image processing device 70. Further, an ON / OFF switch 61 is also provided so that the power can be turned ON / OFF manually. Similarly, the bias power supply device 50 can be turned on / off by remote control from the image processing device 70 or manually by the ON / OFF switch 51.

Next, the internal structure of the heating power supply device 60 will be described with reference to FIG. The heating power supply device 60 includes a power supply ON / OFF switch 61, a power supply unit 62 that supplies electric power, and a variable resistor 63 that adjusts the amount of electric power supplied by the power supply unit 62. An output signal from the platinum temperature sensor 31 is given to the power supply unit 62, and the power supply unit 62 adjusts the amount of output power to the ceramic heater 30 based on this output signal. Therefore, the temperature of the ceramic heater 30 is kept substantially constant. More specifically, when the temperature of the ceramic heater 30 rises and exceeds the allowable temperature, the platinum temperature sensor 31 reacts and gives an output signal of the temperature rise to the power supply unit 62. In the power supply unit 62, the variable resistor 63 is controlled based on this output signal, and the ceramic heater 3
The output power amount to 0 is reduced by a predetermined amount. As the output power amount decreases, the amount of current flowing through the ceramic heater 30 also decreases. Therefore, the temperature of the ceramic heater 30 drops to a constant temperature. Similarly, when the temperature of the ceramic heater 30 drops, the amount of current flowing through the ceramic heater 30 increases, and the temperature of the ceramic heater 30 rises to a constant temperature. By performing the temperature adjustment in this way, the ceramic heater 30 always maintains a substantially constant temperature.

The internal heat generation analysis apparatus of this embodiment is provided with two types of heat generation analysis procedures. Both of these procedures include bias power supply 50 and heating power supply 60.
The power is turned on / off automatically by a remote operation from the image processing apparatus 70, but the operator may manually turn the power on / off by operating the switches 51 and 61.

First, the first heat generation analysis procedure will be described with reference to FIG. IC sample 1 in advance for analysis
The sample chuck 20 corresponding to the size of 0 and the infrared lens 41 having a magnification corresponding to the field of view to be observed are selected and mounted at predetermined positions. Next, the image processing device 7
An instruction is given from 0, and the power supply of the heating power supply device 60 is turned on. In this case, the power supply for the bias power supply device 50 remains off. The power supply of the heating power supply device 60 is O
When it becomes N, a current flows through the ceramic heater 30 and the temperature of the ceramic heater 30 rises. Then, when the temperature of the ceramic heater 30 rises to a predetermined temperature, the platinum temperature sensor 31 operates and the energization amount decreases. Therefore, the ceramic heater 30 continues to maintain a substantially predetermined temperature. The predetermined temperature is an allowable temperature of the IC sample 10, for example, about 100 ° C. In this way, when the ceramic heater 30 keeps the predetermined temperature, the IC sample 1
0 is heated and the amount of radiation from the circuit surface of the IC sample 10 increases. The operator observes the monitor 80 while performing XY
The Z stage 100 is slightly moved, and the target IC pattern is captured by the infrared camera 40. Since the amount of radiation from the circuit surface of the IC sample 10 is increasing, the infrared camera 40
Even if is used, an IC pattern image can be picked up like a visible camera. Then, the IC pattern image 110 captured by the infrared camera 40 is stored in the memory in the image processing device 70 (analysis procedure 1).

Next, an instruction is given from the image processing device 70, and the power source of the heating power source device 60 is turned off. Therefore, the temperature of the IC sample 10 decreases, the amount of radiation from the circuit surface decreases, and the infrared camera 40 cannot capture an image of the IC pattern. Further, the bias power supply device 50 is turned on in response to an instruction from the image processing device 70, and a bias voltage is applied to the circuit of the IC sample 10. By applying the bias voltage, infrared rays are radiated from the heat generating portion of the circuit. An image of the infrared radiation region (that is, an image of a heat generation portion) is used as a heat generation image 120 and the infrared camera 40
And is stored in the memory in the image processing device 70 (analysis procedure 2).

Next, the IC pattern image 110 and the heat generation image 120 are read from the memory according to an instruction from the image processing device 70, and the image showing the heat generation portion of the heat generation image 120 is superimposed on the circuit pattern of the IC pattern image 110. , A superimposed image 130 is created (analysis procedure 3).
The superimpose image 130 created in this way is displayed on the monitor 80, and the operator can easily identify the heat generation portion on the IC pattern from the superimpose image 130.

Next, the second heat generation analysis procedure will be described with reference to FIG. The procedure until the IC pattern image 110 is acquired is the same as the first heat generation analysis procedure.

After the IC pattern image 110 is acquired, an instruction is given from the image processing device 70, and the heating power supply device 60 is provided.
Both the power source of the power source and the power source of the bias power source device 50 are turned off. For this reason, the temperature of the IC sample 10 decreases, the amount of radiation from the circuit surface decreases, and it becomes impossible to capture an image of the IC pattern. Further, since the circuit does not generate heat, infrared rays are not emitted from the circuit. In this state, the heat generation image 121 of the circuit pattern of the IC sample 10
Is captured by the infrared camera 40 (analysis procedure 2).
The heat generation image 121 captured in this way is an image in which only background noise is captured. Next, similar to the first heat generation analysis procedure, the heating power supply device 60
Power is OFF, bias power supply device 50 is ON
In this state, the heat generation image 120 is captured by the infrared camera 40 (analysis procedure 3). The heat generation image 120 thus captured is an image in which the image of the heat generation portion and the background noise are captured.

Next, the heat-generating images 120 and 121 are read from the memory according to an instruction from the image processing apparatus 70, and the heat-generating image 120 is subtracted pixel by pixel from the heat-generating image 121 to generate a heat-generating image 122 (analysis procedure). 4). Fever image 12
1 is an image including an image of a heat generation portion and background noise, and since the heat generation image 120 is an image including only background noise, the background noise of the heat generation image 121 is removed by subtraction. Then, the IC pattern image 110 is read from the memory according to an instruction from the image processing device 70, and the image showing the heat generation portion of the heat generation image 122 is superimposed on the circuit pattern of the IC pattern image 110 to create the superimpose image 130. (Analysis procedure 5). The superimpose image 130 created in this way is displayed on the monitor 80, and the operator can easily identify the heat generation portion on the IC pattern from the superimpose image 130.

The feature of this embodiment is that the IC pattern image 11
The point is that the IC sample 10 is heated only when 0 is imaged and a clear image is acquired by the infrared camera 40. IC
When the sample 10 is at room temperature, the infrared camera 40
It is difficult to capture the pattern image 110. This is because it is difficult to visualize the IC pattern image 110 with the infrared camera 40 because the radiant energy from the IC sample 10 is low at room temperature. Therefore,
In the present embodiment, the temperature of the IC sample 10 is raised by heating the IC sample 10, so that the IC sample 10
The IC pattern image 110 is visualized by increasing the radiant energy of infrared rays radiated from the surface of the IC pattern. Therefore, the infrared camera 40 can also obtain a clear IC pattern image 110.

It is clear from the fact that the radiant energy E is proportional to the fourth power of the absolute temperature, as shown in the equation E = σT ⁴ , that the radiant energy of infrared rays increases as the temperature rises. This can also be seen from the graph of FIG. In the graph shown in the figure, the wavelength of infrared rays emitted from the surface of the IC sample 10 is on the x-axis, the temperature of the IC sample 10 is on the y-axis, and the energy of infrared rays emitted from the surface of the IC sample 10 is on the z-axis. taking it. As can be seen from this graph, the rate of increase in infrared energy due to temperature rise is particularly high in the wavelength range of 3 to 5 μm. Therefore, when the IC sample 10 is heated and infrared rays having a wavelength of 3 to 5 μm are picked up by the infrared camera 40, a clear IC pattern image 110 is obtained.
Can be obtained.

Generally, the infrared camera can be roughly classified into two types, a type having a sensitivity in a band of 3 to 5 μm and a type having a sensitivity in a band of 8 to 13 μm, but in the present embodiment, the infrared camera is classified into a band of 3 to 5 μm. An infrared camera of a type having sensitivity is used. Adopting an infrared camera having sensitivity to low wavelengths in this way is also advantageous in terms of resolution. That is R
= Λ / 2NA (λ: detection wavelength, NA: lens aperture ratio)
As can be seen from the equation, the resolution R is determined by the detection wavelength λ and the lens aperture ratio NA, and the shorter the detection wavelength λ, the higher the resolution R.

As described above, in this embodiment, not only the heat generation image 120 (121, 122) but also the IC pattern image 110 is picked up by using one infrared camera 40. Therefore, the circuit configuration is simpler than that of a conventional internal heat generation analysis device that requires two cameras (visible camera 206 and infrared camera 207), and two images can be combined with high precision. Since it is easy to detect, it is possible to detect a heat generation portion of a fine circuit pattern.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, although the IC sample 10 is used as the object to be measured in this embodiment, a wafer provided with circuit wiring may be used. In this case, it is necessary to use a prober wafer chuck instead of the sample chuck 20. In addition to the semiconductor IC,
It may be a hybrid IC, a film IC, an LSI, or the like. further,
In this embodiment, the ceramic heater 30 is used as the heating means, but a Peltier element may be used instead of the ceramic heater 30.

[0029]

As described in detail above, in the internal heat generation analysis apparatus of the present invention, a pattern image and a heat generation image are picked up by one infrared camera, and these images are combined by a combining means. To create a composite image. The composite image is an image in which an image showing a heat generation portion of the heat generation image is superimposed on the circuit pattern of the pattern image. This composite image is displayed on the display means, and the operator can easily identify the heat generation portion on the circuit pattern by visually observing the composite image. Therefore, it is possible to accurately detect a defective heating portion due to an abnormal current, such as a short circuit pattern.

As described above, the circuit structure is simpler than that of the conventional analyzer which requires two cameras (visible camera and infrared camera), and two images are combined with high precision. Since it is easy to detect, it is possible to detect a heat generation portion of a fine circuit such as a semiconductor IC.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an internal heat generation analysis apparatus according to this embodiment.

FIG. 2 is a block diagram showing an internal structure of a heating power supply device.

FIG. 3 is an analysis procedure chart showing a first heat generation analysis procedure.

FIG. 4 is an analysis procedure chart showing a second heat generation analysis procedure.

FIG. 5 is a graph showing the relationship between temperature and infrared energy.

FIG. 6 is a block diagram showing a configuration of a conventional internal heat generation analysis device.

[Explanation of symbols]

10 ... IC sample, 20 ... Sample chuck, 21 ...
IC socket, 22 ... Printed circuit board, 23 ... Extraction pin,
30 ... Ceramic heater, 31 ... Platinum temperature sensor, 40
Infrared camera, 41 ... Infrared lens, 50 ... Bias power supply device, 51, 61 ... Switch, 60 ... Heating power supply device, 62 ... Power supply unit, 63 ... Variable resistance, 70 ... Image processing device, 80 ... Monitor , 90 ... Heat shield box, 100 ... XY
Z stage, 110 ... IC pattern image, 120 to 12
2 ... Fever image, 130 ... Superimposed image.

Claims (2)

[Claims] 1. A mounting table for mounting an object to be measured whose circuit pattern surface is exposed, a heating means for heating the object to be measured mounted on the table, and an object to be measured mounted on the table. Infrared imaging means for imaging the circuit pattern of the object, power supply means for applying a bias voltage to the circuit of the object to be measured placed on the mounting table, and controlling the heating means, the infrared imaging means and the power supply means. The infrared imaging means images the circuit pattern of the object to be measured heated by the heating means and the circuit pattern of the object to be measured which is not heated by the heating means and to which the bias voltage is applied by the power supply means. ,
An image pickup control unit that obtains a pattern image and a heat generation image, a combining unit that combines the pattern image and the heat generation image obtained by the image pickup control unit to create a combined image, and a combined image that is combined by the combining unit is displayed. And an internal heat generation analysis device. 2. A mounting table for mounting an object to be measured whose circuit pattern surface is exposed, a heating means for heating the object to be measured mounted on the table, and an object to be measured mounted on the table. Infrared imaging means for imaging the circuit pattern of the object, power supply means for applying a bias voltage to the circuit of the object to be measured placed on the mounting table, and controlling the heating means, the infrared imaging means and the power supply means. The circuit pattern of the DUT heated by the heating means and the circuit pattern of the DUT that is not heated by the heating means and is not applied with the bias voltage by the power supply means and the heating by the heating means. Is performed and the circuit pattern of the DUT to which a bias voltage is applied by the power supply means is imaged by the infrared imaging means, and the pattern image, the first heat generation image, and the second
Image capturing control means for obtaining a heat generating image of the first heat generating image, and a first heat generating image from the second heat generating image obtained by the image capturing means.
The heat generation image is subtracted for each pixel to create a third heat generation image, and the third heat generation image and the pattern image are combined to generate a combined image, and a combination performed by the combining unit. An internal heat generation analysis device, comprising: a display unit that displays an image.