JPH04232449A - Thermal expansion displacement analyzing device for semiconductor integrated circuit board - Google Patents

Abstract

PURPOSE:To provide a thermal expansion displacement, analyzing apparatus capable of measuring and analyzing the minute displacement resulting from the thermal expansion of a very small area of a semiconductor integrated circuit with high accuracy at high speeds. CONSTITUTION:Driving currents of a plurality of kinds of frequencies set beforehand are supplied to a plurality of different circuits within a semiconductor integrated circuit by a driving current feeding device. At this time, the local displacement due to the heat generation at the surface of the semiconductor integrated circuit, board is optically detected by a heterodyne interference displacement measuring device. Which of the plurality of kinds of the driving currents contributes to the very small displacement or in which of the circuits the influences of the current are large is judged. Accordingly, the influences of the material, circuit, shape and bonding structure of the part of the minute displacement to the heat generation or the process of the heat radiation at the measuring part can be studied.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for analyzing thermal expansion displacement in a minute area on the surface of a semiconductor integrated circuit board.

0002

2. Description of the Related Art For example, rapid displacement caused by local thermal expansion of a semiconductor integrated circuit board may generate stress within the semiconductor integrated circuit board, causing stress migration.
It is said to be one of the causes of destructive phenomena such as disconnection of fine wiring provided on semiconductor integrated circuit boards and peeling of thin films with different coefficients of thermal expansion from bonding sites, as well as deterioration of the semiconductor itself. Therefore, for operation and failure analysis of complexly structured semiconductor integrated circuit boards, local thermal deformation or thermal expansion of semiconductor integrated circuit boards can be instantaneously measured, and the shape and range of thermal expansion displacement can be accurately determined. It is desirable to understand and analyze the causes of thermal expansion displacement.

0003

[Problems to be Solved by the Invention] Conventionally, the thermal expansion or thermal deformation of a semiconductor integrated circuit board has been measured using a contact displacement meter or a non-contact optical interferometer, or by measuring radiation temperature. The displacement at each location on the semiconductor surface was indirectly calculated by first measuring the surface temperature distribution using a meter, and then setting the temperature gradient and boundary conditions inside the semiconductor in addition to that temperature distribution. However, it has been extremely difficult to measure minute displacements in minute regions with high precision and at high speed, and analysis has also not been easy. In particular, when the current that causes heat generation fluctuates over time, such as alternating current, pulse current, or transient current, thermal expansion occurs in the semiconductor in response to the temporally fluctuating current value. Measuring displacement with high precision is required for analysis of thermal diffusion processes and thermal stress caused by thermal expansion displacement. Moreover, even if the thermal expansion displacement occurring in a semiconductor could be measured with high precision, it would not be possible to analyze in detail what kind of circuit causes the displacement.

The present invention has been made against the background of the above-mentioned circumstances, and its purpose is to measure and analyze minute thermal expansion displacements in minute areas of a semiconductor integrated circuit board with high precision and at high speed. An object of the present invention is to provide a thermal expansion displacement analysis device that can perform a thermal expansion displacement analysis.

[0005]

[Means for Solving the Problems] The gist of the present invention to achieve the above object is to provide an apparatus for analyzing thermal expansion displacement of a semiconductor integrated circuit board, the device comprising: a drive current supply device that supplies drive currents of a plurality of predetermined frequencies to a plurality of different circuits in the semiconductor integrated circuit board in order to generate thermal expansion; A heterodyne interference displacement measurement device that optically detects local displacement due to heat generation, and a displacement of the surface of the semiconductor integrated circuit board based on the local displacement of the surface of the semiconductor integrated circuit board detected by the heterodyne interference displacement measurement device. Find the change curve of
The present invention also includes calculation means for performing frequency analysis on the change curve.

[0006]

[Operation] By doing so, drive currents of multiple types of frequencies predetermined by the drive current supply device can be applied to different circuits in the semiconductor integrated circuit in order to generate thermal expansion locally on the semiconductor integrated circuit board. , the heterodyne interference displacement measuring device optically detects the local displacement due to heat generation on the surface of the semiconductor integrated circuit board, and the computing means detects the local displacement of the semiconductor integrated circuit board detected by the heterodyne interference displacement measuring device. A change curve of the displacement of the surface of the semiconductor integrated circuit board is determined based on the local displacement of the surface of the semiconductor integrated circuit board, and a frequency analysis is performed on the change curve. Furthermore, the measured displacement amount or the frequency spectrum analyzed from the displacement amount is three-dimensionally output on a display device.

Therefore, the thermal expansion minute displacement of a minute area of a semiconductor integrated circuit board can be measured with high accuracy and high response speed by the heterodyne interference displacement measuring device, and the displacement curve obtained in this way can be accurately applied to the frequency. When the analysis is performed, it can be determined which of the plurality of drive currents contributes to the thermal expansion minute displacement, or which circuit has a greater influence of the current, and the thermal expansion minute displacement portion It is possible to investigate the influence of the material, circuit shape, and bonding structure on heat generation, or the process of heat dissipation in the measurement part.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a thermal expansion displacement analysis apparatus for a semiconductor integrated circuit board according to an embodiment of the present invention. In the figure, a heterodyne interference displacement measurement device 1 is used to measure minute displacements caused by local thermal expansion of a semiconductor integrated circuit board 2 . The first reference beat signal SfB output from the heterodyne interference displacement measuring device 1
Measurement beat signals SfWA, SfWB, SfWC, SfW
D, SfWE, and the first measurement beat signal SfD are converted into a signal representing a thermal expansion minute displacement in the signal processing circuit 3, and the microcomputer 4 functions as a calculation means.
supplied to

The microcomputer 4 generates drive currents of a plurality of predetermined frequencies from the analysis drive current generator 5, and supplies them to a plurality of different closed circuits of the semiconductor integrated circuit board 2. Furthermore, the microcomputer 4 causes the objective lens drive circuit 134 to drive the lens actuator 70 in order to move the objective lens of the heterodyne interference displacement measuring device 1 . The microcomputer 4 also uses an XYZ direction drive circuit 132 to sequentially move the minute displacement detection position on the surface of the semiconductor integrated circuit board 2.
, 133, 136, XYZ direction actuators 83, 8
5 and 87 to move the semiconductor integrated circuit board 2 to a desired position.

FIG. 2 shows the optical configuration of the heterodyne interference displacement measuring device 1. As shown in FIG. In the figure, a linearly polarized laser beam outputted from a laser light source 10 passes through an isolator 12 and reaches a polarizing beam splitter 14, and a P-polarized beam having a vibration plane parallel to the plane of FIG. It is split into S-polarized light having a vibration plane. This is because the vibration plane of the laser beam is inclined at 45 degrees with respect to the paper plane of FIG. The P-polarized light has the same frequency f0 as the laser beam, is reflected by the mirror 16, and is passed through the polarizing beam splitter 18. In addition, the above S
After being reflected by mirror 20, the polarized light is passed through acousto-optic modulators 22 and 24 and shifted by frequencies +f1 and -f2 to achieve frequency f0 +
f1 - f2, and then enters the polarizing beam splitter 18. In the polarizing beam splitter 18, the frequency-shifted S-polarized light beam and the P-polarized light beam are superimposed, and then split into two in the non-polarizing beam splitter 26.

The light reflected by the non-polarizing beam splitter 26 passes through an analyzer 2 whose polarization axis is tilted at 45 degrees.
8, the P-polarized light and the S-polarized light interfere with each other, that is, the reference beat frequency fB (=
|f1 − f2|) is detected by the reference beat light sensor 30. Therefore, the frequency f
The reference beat signal SfB of B is the reference beat optical sensor 3
Output from 0.

The light transmitted through the non-polarizing beam splitter 26 is further split into two by the non-polarizing beam splitter 32. Hereinafter, the light beam transmitted through the non-polarizing beam splitter 32 will be referred to as a first light beam, and the light beam reflected by the non-polarizing beam splitter 32 will be referred to as a second light beam.

The above-mentioned first light beam is arranged on the surface (reflection surface) of the semiconductor integrated circuit board 2 which is the member to be measured, on the mirror 38 which is disposed integrally with the objective lens 36, and on the surface of the semiconductor integrated circuit board 2 which is the member to be measured. The light is made incident on a first heterodyne interference optical system constituted by a polarizing beam splitter 40 and the like. Further, the second light flux is made incident on a second heterodyne interference optical system constituted by a mirror 42 disposed integrally with the objective lens 36, a mirror 44 whose position is fixed, a polarization beam splitter 46, and the like.

In the first heterodyne interference optical system, P polarized light of frequency f0 and frequency f0 +f1 -f
The first light beam, which is a composite wave of the S-polarized light and the S-polarized light, is first split by the polarizing beam splitter 40. The P-polarized light transmitted through the polarizing beam splitter 40 is converted into circularly polarized light by passing through the λ/4 plate 50, and is then focused on the surface of the semiconductor integrated circuit board 2 through the objective lens 36. The reflected light from the surface of the semiconductor integrated circuit board 2 passes through the objective lens 36 and is transmitted through the λ/4 plate 50, so that it becomes polarized light whose vibration plane is rotated by 90 degrees with respect to the original P-polarized light. Since it is converted into S-polarized light, it is reflected by the polarizing beam splitter 40 and reaches the analyzer 52. The reflected light from the surface of the semiconductor integrated circuit board 2 undergoes a phase shift and scattering due to minute displacements of the surface.

Of the first light beam, the S-polarized light reflected by the polarizing beam splitter 40 is reflected by a fixed mirror 48 and transmitted through a λ/4 plate 50 to be converted into circularly polarized light. , the light is focused on the surface of the mirror 38 through the focusing lens 54. The reflected light from this mirror 38 passes through the condensing lens 54 again and passes through the λ/4 plate 5.
By transmitting 0, the light is converted into polarized light whose vibration plane is rotated by 90 degrees with respect to the original S-polarized light, that is, P-polarized light, which is transmitted through the polarizing beam splitter 40 and reaches the analyzer 52. Since the polarization axis of this analyzer 52 is inclined by 45 degrees from the plane of vibration of the S-polarized light and the P-polarized light, heterodyne interference between the P-polarized light and the S-polarized light occurs in the light transmitted through the polarizer 52, and this The interference light is detected by the first measurement beat optical sensor 56. As shown in FIG. 3, on the light receiving surface of the first measurement beat optical sensor 56,
In the horizontal direction, the light receiving elements 56A, 56C, 56E
are sequentially located, and in the vertical direction, the light receiving elements 56B,
Five light receiving elements 56A, 56B, 56C, 56D, 56E are arranged so that 56C, 56D are located sequentially.
are arranged. Therefore, the first measurement beat optical sensor 56 outputs five types of first measurement beat signals SfWA, SfWB, SfWC, and SfWD whose frequencies are fW.
, SfWE are output.

In the second heterodyne interference optical system, P polarized light of frequency f0 and frequency f0 +f1 -f
The second light beam, which is a composite wave with the S-polarized light of 2, passes through the mirror 3
3, it is first split by a polarizing beam splitter 46. The P-polarized light transmitted through the polarizing beam splitter 46 is converted into circularly polarized light by being transmitted through a λ/4 plate 58, and then condensed onto the surface of the mirror 42 through a condensing lens 60. The reflected light from the mirror 42 passes through the condenser lens 60 and passes through the λ/4 plate 58 again, thereby becoming polarized light whose vibration plane is rotated by 90 degrees with respect to the original P-polarized light, that is, S-polarized light. It is reflected by the polarizing beam splitter 46 and transmitted to the analyzer 6.
Reach 2.

The S-polarized light reflected by the polarizing beam splitter 46 is converted into circularly polarized light by being transmitted through a λ/4 plate 64, and then condensed onto the surface of a fixed mirror 44 through a condensing lens 66. Ru. The reflected light from the mirror 44 is passed through the condenser lens 66 and the λ/4 plate 64 again, thereby becoming polarized light whose vibration plane is rotated by 90 degrees with respect to the original S-polarized light, that is, P-polarized light. As the light is converted, it passes through the polarizing beam splitter 46 and reaches the polarizer 62. Since the polarization axis of this polarizer 62 is inclined by 45 degrees with respect to the vibration plane of the S-polarized light and the P-polarized light, heterodyne interference between the P-polarized light and the S-polarized light occurs in the light transmitted through the polarizer 62, and this The interference light is the second
Detected by the measurement beat optical sensor 68, the frequency is fD
A second measurement beat signal SfD is output.

The objective lens 36 can be positioned in the optical axis direction by a lens actuator 70. That is, through holes 73, 74, and 75 are formed in the machine frame 72, which is fixed in position, through which the light flux passes, and a cylindrical lens actuator 70 is suspended concentrically with the central through hole 74. A lens holding cylinder 78 that holds the objective lens 36 is fixed to the lower end of the lens actuator 70. In this embodiment, the lens actuator 70 constitutes a driving device that changes the mutual distance between the objective lens 36 and the semiconductor integrated circuit board 2, and is made of, for example, piezoelectric ceramics that can be contracted in the axial direction. The objective lens 36 is positioned in relation to the amount of contraction corresponding to the voltage. Further, the mirrors 38 and 42 are fixed to the lens holding tube 78, and can be moved in the axial direction integrally with the objective lens 36.

The semiconductor integrated circuit board 2 has an objective lens 3.
6 optical axis (Z) direction and two directions perpendicular to the optical axis (X
and the Y direction). That is, as shown in detail in FIG. 4, the sample stage 80 on which the semiconductor integrated circuit board 2 is placed includes a Y-direction moving table 86 and an X-direction moving table that are arranged in an overlapping state on a base 88. 84, and a Z-direction actuator 83, an X-direction actuator 85, and a Y-direction actuator, which are supported by the Z-direction moving table 82 and can be driven minutely by, for example, a pulse motor or a piezo actuator.
The directional actuator 87 allows positioning in the Z direction, the X direction, and the Y direction. The X-direction actuator 85 and the Y-direction actuator 87 are used to sequentially shift the detection position of the thermal expansion displacement of the semiconductor integrated circuit board 2, and the Z-direction actuator 83 is used to shift the detection position of the thermal expansion displacement of the semiconductor integrated circuit board 2. Sample stage 8 within a range greater than the moving distance
This is to adjust the height of 8.

A position detector 138 for detecting the amount of movement of the X-direction moving table 84 is provided in the X-direction actuator 85, and a Y-direction moving table is provided in the Y-direction actuator 87. A position detector 139 for detecting the amount of movement of 86 is provided. These position detectors 138 and 139 are constituted by rotary encoders, generally known optical position detectors or length measuring devices, or the like. Furthermore, the analysis drive current from the analysis drive current generator 5 is supplied to the plurality of closed circuits in the semiconductor integrated circuit board 2 through lead wires 89 .

The signal processing circuit 3 and microcomputer 4 are configured as shown in FIG. 5, for example. In the figure, five light receiving elements 56A, 56B, 56C, 56D, 56 of the first measurement beat optical sensor 56 are shown.
The first measurement beat signal SfWA, Sf output from E
WB, SfWC, SfWD, SfWE are amplifiers 90A
, 90B, 90C, 90D, and 90E, the signals are amplified and then supplied to the waveform monitor circuit 92, respectively.

The waveform monitor circuit 92 determines whether the state of the light beam reaching the first measurement beat optical sensor 56 is a plane wave, a diverging spherical wave, or a converging spherical wave. A signal representing the determination result is output to the data bus line 102 (described later), and a signal of the first measurement beat frequency fW is output to the phase difference detection circuit 106 (described later).
Output to. The waveform monitor circuit 92 is configured as shown in FIG. 6, for example. That is, one digital phase difference detection circuit 94 receives the beat signal SfWB from the light receiving elements 56B and 56C arranged in the vertical direction.
and SfWC phase difference ΔθCB (for example, if the phase angle at the peak position of the beat signal SfWC is θC and the phase angle at the peak position of the beat signal SfWB is θB, then ΔθCB)
θCB = θC - θB) and outputs it to the subtracter 98, while the other digital phase difference detection circuit 96 detects the phase difference between the beat signals SfWD and SfWC from the vertically arranged light receiving elements 56D and 56C. △θDC
(For example, if the phase angle of the peak position of the beat signal SfWC is θC, and the phase angle of the peak position of the beat signal SfWD is θD, then ΔθDC=θD−θC) is detected and output to the subtracter 98. Then, the subtracter 98 subtracts the phase difference ΔθDC from the phase difference ΔθCB, and outputs a subtracted value (ΔθCB−ΔθDC).

If the light beam reaching the first measurement beat optical sensor 56 is a plane wave, the phases of the output signals of the three light receiving elements 56B, 56C, and 56D will be the same as shown in FIG. Furthermore, even if the first measurement beat optical sensor 56 is tilted, as shown in FIG.
The output signal SfWB of the light receiving element 56B located above the
and a light receiving element 56D located below the light receiving element 56C.
The light receiving element 56 located at the center of the output signal SfWD of
The phase with respect to the output signal SfWC of C is the same amount in the front and back direction, that is, the △θCB and △θ
DC shifts in the positive direction. For example, in FIG. 8, the phase shift Δθ of the output signal SfWB with respect to the output signal SfWC is
CB (=θC −θB, positive value) and output signal SfWC
Phase shift of output signal SfWD with respect to ΔθDC (=θ
D−θC, positive value) are equal to each other (ΔθCB
= ΔθDC).

However, if the light flux reaching the first measurement beat optical sensor 56 is a convergent spherical wave, as shown in FIG. Element 56C
According to the above definition, the output signal SfWD relative to the output signal SfWC proceeds together with respect to the output signal SfWC.
The phase shift ΔθDC (=θD −θC ) takes a negative value. On the other hand, if the light flux reaching the first measurement beat optical sensor 56 is a divergent spherical wave, the phases of the output signals SfWB and SfWD are delayed with respect to the output signal SfWC, so that the output signal SfWB with respect to the output signal SfWC is The phase shift ΔθCB (=θC−θB) takes a negative value. Therefore, the output signal S for the above output signal SfWC
The subtraction value (△
θCB−ΔθDC) becomes a value closer to zero as the wave becomes a plane wave.

The comparison/judgment circuit 100 in FIG.
Judgment reference range preset at 0 [upper limit value (positive value) and lower limit value (negative value) indicating the reference range including zero]
and the output signal of the subtracter 98, and when the output value of the subtracter 98 (△θCB - △θDC) is within the judgment reference range, it is determined that it is a plane wave, and the output value of the subtracter 98 is within the judgment reference range. When the output value is larger than the upper limit value of the output value, it is determined that the wave is a convergent spherical wave, and when the output value is smaller than the lower limit value of the determination reference range, it is determined that the wave is a divergent spherical wave. Then, the comparison/determination circuit 100 sends a signal representing the determination result of whether the wave is a plane wave, a convergent spherical wave, or a diverging spherical wave, or what degree of curvature the spherical wave has to the data bus line 102. Output. Note that the upper limit value and lower limit value indicating the judgment reference range preset in the setting device 140 are, for example, values when the surface of the semiconductor integrated circuit board 2 is shifted by a half wavelength from the beam waist position of the irradiated light. , or a value smaller than that by a predetermined amount.

Here, the wavefront state of the light beam propagated to the first measurement beat optical sensor 56 represents the relative positional relationship between the focal position of the objective lens 36 and the surface of the semiconductor integrated circuit board 2. That is, when the surface of the semiconductor integrated circuit board 2 is located at the beam waist position, which is the narrowest part of the light beam condensed by the objective lens 36, the light beam reflected from the surface becomes a plane wave. However, if the surface of the semiconductor integrated circuit board 2 deviates from the beam waist position of the light flux to the side away from the objective lens 36, the light flux propagated to the first measurement beat optical sensor 56 becomes a convergent spherical wave. On the other hand, when the surface of the semiconductor integrated circuit board 2 deviates from the beam waist position of the light flux toward the side approaching the objective lens 36, the light flux propagated to the first measurement beat optical sensor 56 becomes a diverging spherical wave.

In a light wave interference type displacement measuring device, if the sample surface is not located at the beam waist position of the measurement beam, a phase error due to the deviation from the beam waist position will be added to the unevenness information (phase change) of the sample. Therefore, the higher the magnification of the objective lens 36 is, in other words, the higher the magnification is for measuring minute irregularities, the more difficult it becomes to obtain sufficient accuracy. For this reason, in this example, the first
The position of the objective lens 36 is constantly controlled so that the light beam propagated to the measurement beat optical sensor 56 becomes a plane wave, so that the displacement of the surface of the semiconductor integrated circuit board 2 can be measured with high precision.

Returning to FIG. 5, the output signal SfB of the reference beat optical sensor 30 is shaped into a pulse waveform by the waveform shaping circuit 104, and then supplied to the phase difference detection circuit 106, and then passed through the inverter 108 to the AND circuit. 110
supplied to The phase difference detection circuit 106 detects the phase difference D between the signal SfWC of the frequency fW output from the light receiving element 56C and the output signal SfB of the reference beat optical sensor 30, and sends a signal representing this phase difference D to the data bus line. Output to 102. Prior to measuring the surface shape, the light beam reaching the first measurement beat optical sensor 56 is adjusted so as to become a plane wave, so that the objective lens 36 and the surface of the semiconductor integrated circuit board 2 are initially set to optimal optical conditions. The phase difference D detected by the phase difference detection circuit 106 when the position is determined is referred to as an initial phase difference Di.

Output signal S of second measurement beat optical sensor 68
fD is shaped into a pulse waveform by the waveform shaping circuit 112 and then supplied to the AND circuit 110. The AND circuit 110 receives the output signal Sf of the reference beat optical sensor 30.
When the pulse waveform of B is, for example, “0” and the pulse waveform of the output signal SfD of the second measurement beat optical sensor 68 is, for example, “1”, the high-frequency signal generator 114
Counter 1 receives a constant frequency clock signal output from
16 and counted there. This counter 11
6 counts clock signals corresponding to the phase difference between the output signal SfB of the reference beat optical sensor 30 and the output signal SfD of the second measurement beat optical sensor 68, and expires when the clock signal reaches a value corresponding to the phase difference 2π. This is a frequency division counter that outputs a signal and starts counting from zero again. This counter 116 temporarily stores a count value representing a phase difference φ of 2π or less in a latch circuit 118 at predetermined time intervals.
8 outputs a signal representing a phase difference to the data bus line 102 as required. Further, the counter 120 counts the expiration signal outputted when the count value of the counter 116 becomes a value corresponding to a phase difference of 2π, and outputs the count value N representing the phase difference in units of 2π to a latch circuit at predetermined time intervals. 122, and the latch circuit 122 outputs a signal representing the count value N to the data bus line 102 as necessary. Therefore, the actual phase difference Φ (=2πN+φ) between the output signal SfB of the reference beat optical sensor 30 and the output signal SfD of the second measurement beat optical sensor 68 is detected by the output signals of the latches 118 and 122. It has become.

The microcomputer 4 includes a CPU 124
, RAM 126, ROM 128, etc. The CPU 124 processes the input signal according to a program stored in the ROM 128 in advance while utilizing the storage function of the RAM 126, and positions the surface of the semiconductor integrated circuit board 2 at the beam waist position of the light beam focused by the objective lens 36. Before and during measurement, drive power is supplied from the objective lens drive circuit 134 to the lens actuator 70.
to control the position of the objective lens 36. Also,
During surface displacement measurement, the CPU 124 causes the X-direction drive circuit 132 and the Y-direction drive circuit 133 to supply drive power to the X-direction actuator 85 and the Y-direction actuator 87 to bring the semiconductor integrated circuit board 2 into the measurement range of its surface. Move horizontally by the corresponding distance. Furthermore, the CPU 124 calculates the thermal expansion displacement of the surface of the semiconductor integrated circuit board 2 from the phase difference Φ obtained during the measurement and the moving distance of the semiconductor integrated circuit board 2 detected by the phase detectors 138 and 139. The cross-sectional shape or three-dimensional shape of the fine thermal expansion displacement and its change curve over time are displayed as images on the display 130, or the frequency analysis curve or frequency analysis value of the change curve is displayed.

The operation of the measurement control circuit will be explained below based on the flowchart shown in FIG. First, in step S1, the semiconductor integrated circuit board 2 placed on the sample stage 80 is moved to a predetermined measurement start position. This movement is automatically performed in conjunction with the operation of a measurement start switch (not shown). In the next step S2, the X-direction actuator 8 is
5 and the Y-direction actuator 87, the surface shape of the semiconductor integrated circuit board 2 is measured, and the measured data is stored in a storage element such as a RAM. Thereafter, in step S3, the semiconductor integrated circuit board 2 placed on the sample stage 80 is moved again to a predetermined measurement start position. In the subsequent step S4, a drive signal is supplied from the Z-direction drive circuit 136 to the Z-direction actuator 83, so that the surface of the semiconductor integrated circuit board 2 placed on the sample stage 80 is focused by the objective lens 36. It is positioned approximately at the beam waist position of the luminous flux. Next, in step S5, the lens actuator 7
0, the position is controlled so that the beam waist position and the surface of the semiconductor integrated circuit board 2 are precisely aligned. In steps S4 and S5, control is performed based on the signal output from the waveform monitor circuit 92 so that the wavefront of the light beam reaching the first measurement beat optical sensor 56 becomes flat. As a result, the initial position is accurately set, and in step S5, the phase difference D detected by the phase difference detection circuit 106 is stored as the initial phase difference Di.

In step S6, analysis drive currents of a plurality of different frequencies are continuously supplied from the analysis drive current generator 5 to a plurality of predetermined closed circuits formed within the semiconductor integrated circuit board 2. Then, in step S7,
For example, the phase difference Φ(t
) is read, and the thermal expansion displacement Z is calculated based on the amount of change in the phase difference Φ(t) according to the following equation (1).

[0034]

[Math 1]

[0035] However, λ is the wavelength of light, and Φ(t0) is the time t
The phase difference at time 0, Φ(t1), is the phase difference at time t1.

Subsequently, in step S8, the supply of the analysis drive current is stopped, and then, in step S9, it is determined whether or not to end the measurement. The end of this measurement is determined when the measurement end button is operated or when the measurement of the preset thermal expansion displacement inspection area is completed. If the determination in step S9 is negative, the semiconductor integrated circuit board 2 is moved to the next predetermined thermal expansion displacement measurement point by operating the X-direction actuator 85 and the Y-direction actuator 87 in step S10. After that, steps S4 and subsequent steps are executed again. Then, while the above steps are repeated,
If the judgment in step S9 is affirmed, step S1
In step 1, the thermal expansion displacement at each measurement point obtained so far is displayed three-dimensionally, a thermal expansion displacement curve at each measurement point is obtained, and a frequency analysis is performed on the thermal expansion displacement curve. The thermal analysis results are displayed for each measurement point.

[0037] Here, the frequency analysis for the thermal expansion displacement curve in step S11 will be explained. Generally, as shown in the applied voltage in FIG.
If a DC analytical driving current is applied for a certain period of time to a predetermined closed circuit of As a result, Joule heat is generated, and the thermal expansion displacement caused by the Joule heat changes as shown in FIG. Similarly, if a pulsed analysis drive current of a constant frequency is applied for a certain period of time to a predetermined closed circuit of the semiconductor integrated circuit board 2 as shown in the applied voltage in FIG. 13, as shown in FIG. A thermal expansion displacement curve having displacement pulsations corresponding to the pulse frequency of the analysis drive current is obtained. Therefore, by subjecting the thermal expansion displacement curve to frequency analysis, the pulse frequency f1 of the drive current that contributed to the thermal expansion displacement can be easily detected as shown in FIG. Since time-series thermal expansion displacement data is obtained for each position on the semiconductor integrated circuit board,
On the other hand, by performing Fourier analysis, a frequency spectrum of thermal expansion displacement can be obtained. In this step S11, first, the surface shape of the semiconductor integrated circuit board 2 measured before energization is displayed three-dimensionally on the display 130, and then thermal expansion displacement data d(xi, yi, t
By displaying 1) three-dimensionally on the display 130, the state of thermal deformation at time t=t1 can be three-dimensionally expressed. Thermal displacement data d(xi, y
By displaying i, ti) in three dimensions, it is possible to observe thermal deformation actually occurring in the semiconductor integrated circuit over time.

Furthermore, data Sf(xi
, yi) on the display 130 in a three-dimensional manner, the thermal expansion displacement spectrum at each point on the semiconductor integrated circuit board can be observed. When drive currents of a plurality of predetermined frequencies are supplied by the current generator 5 to a plurality of different circuits in the semiconductor integrated circuit board 2, the local The displacement differs depending on the measurement position, and the thermal expansion displacement spectrum contains information about which of the multiple types of drive current contributes to the thermal expansion minute displacement, or which circuit has the greater influence of the current. As shown in FIG. 16, this appears as a difference in frequency or a difference in spectral intensity in the frequency spectrum, so it is possible to investigate in detail the influence of the material, circuit shape, and bonding structure on heat generation in minute parts of the semiconductor integrated circuit board. The method described above is also effective in detecting wire breaks that cannot be identified even by visual inspection using a magnifying glass. In other words, the shape or amount of displacement of the thermal expansion displacement curve is different depending on whether or not there is a disconnection, or if there is a disconnection when comparing the thermal expansion displacement spectra. Since changes appear in the observed spectrum when not used, it can also be applied to inspecting disconnections, etc.

Although one embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the above-described embodiment, the analysis drive current was in the form of a pulse that turned on and off at a predetermined frequency, but it may also be an alternating current.

Further, the heterodyne interference displacement measuring device 1 of the above-described embodiment includes a mechanism and control means for maintaining a constant distance between the objective lens 36 and the surface of the semiconductor integrated circuit board 2 in order to convert the reflected light into a plane wave. However, other types of heterodyne interferometric displacement measurement devices that do not include such a mechanism and control means may be used.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[0043]

[Effect of the invention] As is clear from the detailed description above,
According to the present invention, it is possible to measure and analyze thermal expansion displacement in a minute area of a semiconductor integrated circuit board with high precision and high speed. A device for analyzing the diffusion process can be provided.

[Brief explanation of the drawing]

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

FIG. 2 is a diagram illustrating the configuration of the heterodyne interference displacement measurement device of FIG. 1;

FIG. 3 is a diagram showing the configuration of a first measurement beat optical sensor in FIG. 2;

FIG. 4 is a diagram showing the configuration of each moving table that supports the sample stage in FIG. 2;

FIG. 5 is a block diagram showing the configuration of the signal processing circuit, microcomputer, etc. in FIG. 1;

FIG. 6 is a diagram showing the configuration of the waveform monitor circuit of FIG. 5;

FIG. 7 is a diagram showing a state in which a plane wave is incident on the first measurement beat optical sensor.

FIG. 8 is a diagram illustrating a state where a phase difference occurs due to an inclination even though the wave is a plane wave.

FIG. 9 is a diagram showing a state in which a spherical wave is incident on the first measurement beat optical sensor.

FIG. 10 is a flowchart illustrating the operation of the microcomputer in FIG. 1;

FIG. 11 is a diagram showing applied voltage when the analysis drive current is direct current.

FIG. 12 is a diagram showing a thermal expansion displacement waveform generated by the analytical drive current.

FIG. 13 is a diagram showing applied voltage when the analysis drive current is pulsed.

FIG. 14 is a diagram showing a thermal expansion displacement waveform generated by the analysis drive current.

FIG. 15 is a diagram showing a frequency analysis result of the thermal expansion displacement waveform.

FIG. 16 is a diagram showing frequency analysis results of thermal expansion displacement waveforms having signal intensities at different frequencies.

[Explanation of symbols]

1 Heterodyne interference displacement measuring device 2 Semiconductor integrated circuit board

Claims (1)

[Claims] 1. An apparatus for analyzing thermal expansion displacement of a semiconductor integrated circuit board, the apparatus comprising: a driving current having a plurality of predetermined frequencies to generate thermal expansion locally on the semiconductor integrated circuit board; a drive current supply device that supplies a plurality of different circuits in the semiconductor integrated circuit board; a heterodyne interference displacement measurement device that optically detects local displacement due to heat generation on the surface of the semiconductor integrated circuit board; calculation means for determining a change curve of displacement of the surface of the semiconductor integrated circuit board based on the local displacement of the surface of the semiconductor integrated circuit board detected by the interference displacement measurement device, and performing frequency analysis on the change curve; A thermal expansion displacement analysis device for a semiconductor integrated circuit board, comprising: