JP2000310518A - Three-dimensional shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the high-speed measurement of the three-dimensional shape of a sample. SOLUTION: A three-dimensional shape measuring device is provided with a light source 1 to generate low-coherence illuminating light, a light pencil dividing means 6 to divide the illuminating light into a reference light pencil incident onto a reference surface 11 and a light pencil for measurement incident onto a sample 7, an illuminating optical system 5 to converge the illuminating light onto the sample 7, a light pencil synthesizing means 6 to synthesize the reference light pencil and the light pencil for measurement, a means to move the sample 7 orthogonally to the optical axis of the illuminating optical system 5, a means to detect the location of the sample 7 in a plane orthogonal to the optical axis of the illuminating optical system 5, a means to detect the difference of length between the optical paths of the reference optical pencil and the light pencil for measurement, a light detecting means 14, and a signal computing means 15 to compute a signal detected by the light detecting means 14. With the sample 7 in a sate of moving orthogonally to the optical axis of the illuminating optical system 5, the three-dimensional shape measuring device detects a signal by the light detecting means 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a three-dimensional shape measuring device, and more particularly to a three-dimensional shape measuring device for observing the surface shape of a sample using light.

[0002]

2. Description of the Related Art With the advance of technology, the miniaturization of samples has progressed, and higher speed and higher accuracy are required in three-dimensional shape measurement. In the field of semiconductors as well, the miniaturization of samples has been progressing, and surface-mount LSI packages (BGA: ball grid array, CSP: chip scale package, etc.) have attracted attention as a technology corresponding to miniaturization.

As a method for measuring a sample with high accuracy, a white interferometer, a confocal microscope, and the like are known. The white interferometer performs a large number of measurements while changing the optical path length difference between the sample and the reference surface using light with low coherence, as shown in Japanese Patent Publication No. Is detected as a surface.

An improved example for speeding up the measurement by a white light interferometer is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 8-219722. In this method, two different tomographic images in the height direction are obtained with respect to a sample on which bumps are formed, and the pass / fail judgment of the bump height is performed based on the obtained results.

There is a confocal microscope as a method for measuring a three-dimensional shape with high accuracy. The confocal microscope is a known technique.
No. -311025. A two-dimensional imaging unit is prepared separately from the measurement system, and an area to be measured is extracted from the image. As a result, the measurement area can be limited, and the measurement time can be reduced.

[0006]

In order to measure the three-dimensional shape of a sample using a white light interferometer, measurement is performed many times at different heights in the optical axis direction, and the surface shape is calculated from the results. There is a problem that it takes a lot of time.

Further, since the shape obtained as a result is limited to the range of the field of view of the optical system, it has been necessary to repeat the measurement after moving the sample in order to measure a large sample. To use for 100% inspection of
There is a problem that the measurement throughput is too low.

As a countermeasure, a method using two different scanning results in the height direction has been proposed in Japanese Patent Laid-Open No. 8-219722, but it is necessary to scan the same portion twice.
There is a problem that the measurement time is not shortened. further,
Between the first scan and the second scan, a positioning error occurs due to the accuracy of the stage.

In a confocal microscope also, it is necessary to perform a plurality of measurements at different heights at the same location, and there is a problem that the measurement time becomes long. In order to solve this problem, a method of preparing a two-dimensional imaging means separately from the measurement system and limiting the measurement area has been proposed in Japanese Patent Laid-Open No. Hei 7-311025. In particular, in the case of a large sample, it is difficult to perform the control at a high speed, which hinders a reduction in measurement time.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a three-dimensional shape measuring apparatus capable of measuring a three-dimensional shape of a sample with high accuracy and at high speed. It is in.

[0011]

A first three-dimensional shape measuring apparatus according to the present invention, which achieves the above object, comprises: a light source for generating illumination light having low coherence; a reference light beam for projecting the illumination light to a reference surface; A light beam splitting means for splitting the measurement light beam incident on the sample, an illumination optical system for condensing the measurement light beam on the sample, a light beam combining device for synthesizing the reference light beam and the measurement light beam, and an illumination optical system for the sample. Means for moving the sample in a direction perpendicular to the optical axis, means for detecting the position of the sample in a plane perpendicular to the optical axis of the illumination optical system or an equivalent amount thereof, An optical path length difference, or a unit for detecting an amount equivalent to the optical path length difference; a light detection unit; and a signal calculation unit for calculating a signal detected by the light detection unit. While moving in the direction perpendicular to the axis, It is characterized in that to detect the more signals.

In this three-dimensional shape measuring apparatus, since the measurement is performed while the sample is moving in the direction perpendicular to the optical axis of the illumination optical system, there is no need to perform control such as stopping and moving, and the white Since interference measurement can be performed, high-speed and high-precision measurement can be performed.

According to a second three-dimensional shape measuring device of the present invention, in the first three-dimensional shape measuring device, the signal calculating means is means for setting a threshold value, and means for comparing a signal from the light detecting means with the threshold value. And when a signal exceeding the threshold value is generated, means for storing the optical path length difference at that time and the position of the sample in a plane perpendicular to the optical axis of the illumination optical system, and information from the storage means Means for calculating the shape of the sample.

In the interference measurement using a light source with low coherence, a change in the interference intensity is observed only in the vicinity where the optical path length difference between the reference surface and the sample surface becomes zero. Therefore, in this three-dimensional shape measuring apparatus, the surface shape of the sample can be calculated by performing signal processing only at points where the signal from the light detecting means has reached a certain value or more.

A third three-dimensional shape measuring apparatus according to the present invention is characterized in that, in the first or second three-dimensional shape measuring apparatus, the light detecting means is a one-dimensional line sensor.

According to a fourth three-dimensional shape measuring apparatus of the present invention, the one-dimensional line sensor is a one-dimensional CCD in the third three-dimensional shape measuring apparatus.

In these three-dimensional shape measuring devices,
Since the light detecting means is a one-dimensional line sensor, the time required to read outputs from all pixels is shorter than when a two-dimensional sensor is used, so that the moving speed of the sample can be increased, It is possible to respond to high-speed measurement.

According to a fifth three-dimensional shape measuring apparatus of the present invention, in any one of the first three-dimensional shape measuring apparatus to the fourth three-dimensional shape measuring apparatus, the optical path length difference between the reference light beam and the measuring light beam is periodically calculated. It is characterized in that it has a means for dynamically changing.

Since the interference measurement by the laser is based on a minute amount called the wavelength of light, the displacement can be measured with extremely high accuracy. However, lasers have a long coherence length,
Additional methods are needed to uniquely determine the absolute position of the sample. On the other hand, in the interference measurement using low coherence light such as white light, as shown in FIG. 6, the relationship between the optical path length difference and the interference intensity indicates that the coherent distance is short and the optical path length difference between the reference surface and the sample is zero. , The interference intensity becomes maximum, and the intensity change rapidly decreases as the position deviates therefrom. Therefore, the position of the sample can be calculated from the position of the reference surface when the intensity of the interference fringes is maximized.

When the sample is moved with the optical path length difference between the reference light beam and the measurement light beam kept at a constant value, only information on a specific height of the sample can be obtained. By periodically changing the optical path length difference between the reference light beam and the measuring light beam as in this three-dimensional shape measuring apparatus, information on the range in the height direction corresponding to the change in the optical path length difference can be obtained.

According to a sixth three-dimensional shape measuring apparatus of the present invention, in the fifth three-dimensional shape measuring apparatus, the means for periodically changing the optical path length difference between the reference light beam and the measuring light beam changes the optical path length. It is characterized by the fact that the period to be changed is variable.

In this three-dimensional shape measuring apparatus, the period for changing the optical path length difference is made variable. For example, for a sample whose surface shape changes drastically, the period for changing the optical path length is shortened, and For a sample that shows a gradual change in shape, measurement can be performed under optimal conditions according to the sample, such as by increasing the period of changing the optical path length.

Alternatively, even in a single sample, the period can be changed depending on the location, such as short in a place where the shape change is drastic, and long in a gentle place, so that measurement can be performed under optimum conditions over the entire sample. become.

According to a seventh three-dimensional shape measuring apparatus of the present invention, in the fifth three-dimensional shape measuring apparatus or the sixth three-dimensional shape measuring apparatus, the optical path length difference between the reference light beam and the measuring light beam is periodically determined. The changing means has a mechanism for displacing the reference surface in the optical axis direction.

In this three-dimensional shape measuring apparatus, since the reference surface can be made smaller than the sample by moving the sample in a certain direction and measured, the difference in optical path length between the reference light beam and the measuring light beam is obtained. As a means for periodically changing, the scanning mechanism is simpler than when the sample is displaced.

According to an eighth three-dimensional shape measuring apparatus of the present invention, in the seventh three-dimensional shape measuring apparatus, an optical path length difference between the reference light beam and the measuring light beam or an amount equivalent to the optical path length difference is detected. The means has means for detecting displacement of the reference surface in the optical axis direction.

In this three-dimensional shape measuring apparatus, the means for detecting the optical path length difference between the reference light beam and the measuring light beam, or the amount equivalent to the optical path length difference, detects the displacement of the reference surface in the optical axis direction. Since this is a means, it is possible to detect the amount of displacement of the reference plane directly corresponding to the optical path length, so that the processing of the measurement results is simplified.

According to a ninth three-dimensional shape measuring apparatus of the present invention, in the eighth three-dimensional shape measuring apparatus, the means for detecting the displacement of the reference surface in the optical axis direction is a laser length measuring device. Things.

In this three-dimensional shape measuring apparatus, since the means for detecting the displacement of the reference surface in the optical axis direction is a laser length measuring device, the displacement can be measured with high accuracy.

[0030] The tenth three-dimensional shape measuring apparatus of the present invention comprises:
In the seventh three-dimensional shape measuring apparatus, a mechanism for displacing the reference surface in the optical axis direction is a piezo actuator, and detects a difference in optical path length between the reference light beam and the measuring light beam, or an amount equivalent to the optical path length difference. Means for detecting the driving voltage of the piezo actuator.

In this three-dimensional shape measuring apparatus, an amount equivalent to the optical path length difference between the reference light beam and the measuring light beam can be detected by measuring an electric quantity called a driving voltage of the piezo actuator. It is simple, and the measurement is easy even when the frequency at which the optical path length difference changes becomes high.

An eleventh three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the first to tenth three-dimensional shape measuring apparatuses, the moving speed of the sample is made variable by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. It is characterized by the following.

In this three-dimensional shape measuring apparatus, since the moving speed of the sample is variable, the moving speed of the sample is reduced, for example, for a sample whose surface shape changes drastically, and the surface changes gradually in shape. For the sample shown, measurement can be performed under optimum conditions according to the sample, such as increasing the moving speed of the sample.

Alternatively, even within a single sample, the moving speed can be changed depending on the position, such as slow in a place where the shape change is severe and fast in a gentle place, so that the measurement can be performed under the optimum conditions over the entire surface of the sample. Will be possible.

A twelfth three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the first to tenth three-dimensional shape measuring apparatuses, the sample is moved at a constant speed by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. It is characterized by the following.

In this three-dimensional shape measuring apparatus, since the moving speed of the sample is fixed, stable control is possible even when the sample becomes large.

A thirteenth three-dimensional shape measuring apparatus according to the present invention comprises:
In the eleventh three-dimensional shape measuring device or the twelfth three-dimensional shape measuring device, the sample is characterized in that a substantially periodic structure is formed on a substrate.

In this three-dimensional shape measuring apparatus, since the sample has a structure in which a substantially periodic structure is formed on the substrate, the shape of the sample is changed in consideration of the change of the sample shape within one period. If the moving speed is determined, optimum measurement conditions can be set for the entire surface.

A fourteenth three-dimensional shape measuring apparatus according to the present invention comprises:
In the thirteenth three-dimensional shape measuring apparatus, the position on the measurement light beam where the optical path length difference between the reference light beam and the measurement light beam becomes zero when the reference surface is displaced is the height of the vertex of the substantially periodic structure. And not including the height of the substrate.

In this three-dimensional shape measuring apparatus, when it is sufficient to measure the vicinity of the vertex of a substantially periodic structure, when the reference surface is displaced, the optical path length difference between the reference light beam and the measuring light beam becomes zero. Since the position on the measuring light beam includes the height of the vertex of the substantially periodic structure and does not include the height of the substrate, the width of displacing the reference surface can be reduced, and the reference surface is moved to a higher frequency. Can be displaced.

A fifteenth three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the first to fourteenth three-dimensional shape measuring apparatuses, the sample is a surface-mounted semiconductor package in which spherical bumps are arranged on the substrate substantially periodically, and the reference surface is v _s / _{(2Rsinθ b)} at a frequency higher than [Hz], and, R × _{^{[1- (1-sin 2 θ b}} )
^[1/2 ]] in the optical axis direction. Here, NA: numerical aperture on the sample side of the illumination optical system R: radius of the spherical surface when the bump shape is approximated by a spherical surface _vs : speed when the sample is moved at a constant speed θ _b : θ _b = (sin ⁻¹ NA ) / 2.

In the case where the sample is a surface-mount type semiconductor package in which a hemispherical bump is formed on a substrate, when light is measured by an optical system having a finite aperture value, reflected light from the vicinity of the apex of each bump is reflected by the optical system. However, the reflected light from the periphery has an increased angle and cannot be captured by the optical system. This is schematically shown in FIG. A hemispherical bump is formed on the substrate, and when it is observed with an optical system having a sample-side numerical aperture NA, reflected light from the substrate can be captured by the optical system, but the light is vertically incident on the bump. the illumination light returns to the optical system is reflected is limited to the position of the region where the reflection angle theta _r from the bump apex is NA> sin [theta _r. Therefore, when the sample shape is considered to be a hemisphere, there is a relationship of θ _r = 2θ _b , so that sin 2θ _b
= NA, that is, only the angle range indicated by oblique lines in the figure can be measured (in this case, θ _b =
(Sin ^-1 NA) / 2. ). Therefore, even if the reference surface is displaced so as to cover from the upper surface of the substrate to the apex of the bump for the measurement of the bump shape, only the reflected light from the substrate and the vicinity of the bump apex will be observed. One of the most important items in the measurement of the bump shape is coplanarity (how much the height of the vertex of each bump deviates from the reference plane). For that purpose, it is sufficient to measure the range where the illumination light around the vertex of the bump returns. Figure, shaded areas, x direction has a spread of diameters 2Rsinshita _b, spread t in the height direction R × [1- (1-sin
² θ _b ) ^1/2 ]. In order to calculate the height of the vertex of each bump, measurement may be performed on the shaded portion.

Consider return light from the bump to the light detecting means. When the moving speed of the stage and v _s, the return light from one bump is detected 2Rsinθ _b / v
_s [s]. At that time, in order to calculate the bump height, it is desirable that the reference surface vibrate for one cycle or more within the time. Therefore, the reference plane is defined as v _s / (2Rs
inθ _b ) [Hz] or higher, and amplitude R × [1-
It is desirable to vibrate at an amplitude of (1-sin ² θ _b ) ^1/2 ] or more.

If the measurement is performed in accordance with the displacement frequency and amplitude of the reference surface necessary for measuring the height of the bump apex, the measurement can be performed while shortening the measurement time and ensuring the accuracy.

A sixteenth three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the first to fifteenth three-dimensional shape measuring apparatuses, the apparatus has a means for measuring a distance between the illumination optical system and the sample or an equivalent amount thereof. is there.

A seventeenth three-dimensional shape measuring apparatus according to the present invention comprises:
In the sixteenth three-dimensional shape measuring apparatus, means for measuring the distance between the illumination optical system and the sample, or an equivalent amount thereof,
It is characterized by being an autofocus device.

In the configuration of the fifteenth three-dimensional shape measuring apparatus,
Only the relative change in the height of the vertex of each bump can be measured,
These three-dimensional shape measuring apparatuses have a means for measuring the distance between the illumination optical system and the sample or an equivalent amount thereof, so that the bump height can be measured. The value can be determined.

An eighteenth three-dimensional shape measuring apparatus according to the present invention comprises:
A light source for generating illumination light, an illumination optical system for condensing the illumination light on the sample, an imaging optical system for forming an image of light from the sample, and a light beam diameter limiting means arranged near a position conjugate with the sample. Means for detecting the relative position in the optical axis direction of the sample and the position conjugate with the light beam diameter limiting means, or an equivalent amount thereof, and moving the sample in a direction perpendicular to the optical axis of the illumination optical system. Means for detecting the position of the sample in a plane perpendicular to the optical axis of the illumination optical system, or an amount equivalent thereto, light detecting means, and calculating a signal detected by the light detecting means. Signal calculating means, wherein a signal is detected by the light detecting means while the sample is moving in a direction perpendicular to the optical axis of the illumination optical system.

In this three-dimensional shape measuring apparatus, the measurement is performed while the sample is moving in the direction perpendicular to the optical axis of the illumination optical system. Therefore, there is no need to perform control such as stopping and moving. Since focus measurement can be performed, high-speed and high-precision measurement can be performed.

A nineteenth three-dimensional shape measuring apparatus according to the present invention comprises:
In the eighteenth three-dimensional shape measuring apparatus, the signal calculation means includes: means for setting a threshold; means for comparing a signal from the light detection means with the threshold; and when a signal exceeding the threshold is generated, Relative position in the optical axis direction of the sample and the position conjugate with the beam diameter limiting means, or an equivalent amount thereof,
It is characterized by comprising means for storing the position of the sample in a plane perpendicular to the optical axis of the illumination optical system, and means for calculating the shape of the sample from information in the storage means.

In the confocal measurement, strong return light is observed only near the position where the sample surface coincides with the position conjugate with the beam diameter limiting means. Therefore, if the signal processing is performed only at a point where the signal from the light detecting means has reached a certain value or more by the three-dimensional shape measuring apparatus, the surface shape of the sample can be calculated.

A twentieth three-dimensional shape measuring apparatus according to the present invention comprises:
In the eighteenth three-dimensional shape measuring device or the nineteenth three-dimensional shape measuring device, the light detecting means is a one-dimensional line sensor.

A twenty-first three-dimensional shape measuring apparatus according to the present invention comprises:
In the twentieth three-dimensional shape measuring apparatus, the one-dimensional line sensor is a one-dimensional CCD.

In these three-dimensional shape measuring devices,
Since the light detecting means is a one-dimensional line sensor, the time required to read the outputs from all the pixels is shorter than when a two-dimensional sensor is used, so that the moving speed of the sample can be increased. Thus, it is possible to respond to high-speed measurement.

A twenty-second three-dimensional shape measuring apparatus according to the present invention comprises:
In the eighteenth three-dimensional shape measuring device or the nineteenth three-dimensional shape measuring device, the light beam diameter limiting means is a pinhole.

In this three-dimensional shape measuring apparatus, since the light beam diameter limiting means is a pinhole, high resolution can be obtained in both the optical axis direction and the two-dimensional direction in the sample plane.

According to a twenty-third three-dimensional shape measuring apparatus of the present invention,
In any one of the eighteenth three-dimensional shape measuring apparatuses to the twenty-first three-dimensional shape measuring apparatuses, the light beam diameter limiting means is a slit.

In this three-dimensional shape measuring apparatus, since the light beam diameter limiting means is a slit, scanning of the illumination light is unnecessary, so that the measurement time can be reduced while maintaining the resolution in the optical axis direction.

The twenty-fourth three-dimensional shape measuring apparatus of the present invention comprises:
In any one of the eighteenth three-dimensional shape measuring apparatus to the twenty-first three-dimensional shape measuring apparatus, the light beam diameter limiting means is a multi-pinhole array.

In this three-dimensional shape measuring apparatus, since the light beam diameter limiting means is a multi-pinhole array, scanning of the illumination light is not required, so that the measurement time can be shortened, and two-dimensional measurement in the optical axis direction and in the sample plane is possible. There is an advantage that the resolution is high in both directions.

A twenty-fifth three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the eighteenth to twenty-fourth three-dimensional shape measuring apparatuses, a means for periodically changing the relative position in the optical axis direction between the position conjugate with the light beam diameter limiting means and the sample is provided. It is characterized by having.

In the confocal measurement, only the return light from the sample at a position conjugate with the light beam diameter limiting means reaches the photodetector, and therefore has a high resolution in the optical axis direction. If the sample is moved while keeping the relative position in the optical axis direction of the sample at a position conjugate with the beam diameter limiting means constant, only information on a specific height of the sample can be obtained. In this three-dimensional shape measuring apparatus, by periodically changing the relative position in the optical axis direction with respect to the sample at the position conjugate with the light beam diameter limiting means, the height in the height direction corresponding to the change in the relative position is changed. Range information can be obtained, and high-speed three-dimensional measurement can be performed.

A twenty-sixth three-dimensional shape measuring apparatus according to the present invention
In the twenty-fifth three-dimensional shape measuring apparatus, the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position in the optical axis direction of the sample periodically changes the position of the light beam diameter limiting means. A three-dimensional shape measuring device having a mechanism for causing the three-dimensional shape to be measured.

A twenty-seventh three-dimensional shape measuring apparatus according to the present invention
In the twenty-sixth three-dimensional shape measuring apparatus, the relative position in the optical axis direction between the sample and the position conjugate with the light beam diameter limiting means or the means for detecting the equivalent amount is determined by the position of the light beam diameter limiting means. It is characterized by having means for detecting.

According to a twenty-eighth three-dimensional shape measuring apparatus of the present invention,
In the twenty-fifth three-dimensional shape measuring apparatus, the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position of the sample in the optical axis direction periodically changes the position of the illumination optical system. It is characterized by having a mechanism.

A twenty-ninth three-dimensional shape measuring apparatus according to the present invention
In the twenty-eighth three-dimensional shape measuring apparatus, the means for detecting the relative position in the optical axis direction between the sample and the position conjugate with the light beam diameter limiting means or the equivalent amount detects the position of the illumination optical system. It is characterized by having a means for performing.

A thirtieth three-dimensional shape measuring apparatus according to the present invention comprises:
In the twenty-fifth three-dimensional shape measuring apparatus, the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position in the optical axis direction with respect to the sample periodically changes the position of the imaging optical system. It is characterized by having a mechanism for causing it to.

A thirty-first three-dimensional shape measuring apparatus according to the present invention comprises:
In the thirtieth three-dimensional shape measuring apparatus, a means for detecting a relative position in the optical axis direction between the sample and a position conjugate with the light beam diameter limiting means, or an equivalent amount thereof, determines the position of the imaging optical system. It is characterized by having means for detecting.

In the twenty-sixth, twenty-eighth, and thirtieth three-dimensional shape measuring apparatuses, the means for periodically changing the relative position in the optical axis direction between the position conjugate with the light beam diameter limiting means and the sample includes the sample. As compared to displacing the position in the direction of the optical axis, the beam diameter limiting means, the illumination optical system, and the imaging optical system, which are components of the measuring device, are smaller, so it is easier to displace them. It is.

In the twenty-seventh, twenty-ninth, and thirty-first three-dimensional shape measuring apparatuses, the means for detecting a change in the relative position in the optical axis direction between the sample and the position conjugate with the light beam diameter limiting means is an optical system. Since the mechanism for detecting the position of the component is adopted, a position conjugate with the light beam diameter limiting means can be calculated from the result. This is a much simpler method than actually measuring a position conjugate with the beam diameter limiting means.

A thirty-second three-dimensional shape measuring apparatus according to the present invention comprises:
A twenty-fifth three-dimensional shape measuring apparatus characterized in that the period is variable in the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position of the sample in the optical axis direction. It is.

In this three-dimensional shape measuring apparatus, the period for changing the position conjugate with the light beam diameter limiting means and the relative position in the optical axis direction with respect to the sample is made variable. Depending on the sample, the period for changing the relative position is shortened for the sample to be shown, and the period for changing the relative position is increased for the sample whose surface shows a gradual shape change. Measurement under optimal conditions becomes possible.

Alternatively, even in a single sample, the period can be changed depending on the location, such as short in a place where the shape change is drastic, and long in a gentle place, so that measurement can be performed under the optimum condition over the entire sample. become.

A thirty-third three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the eighteenth to twenty-fifth three-dimensional shape measuring apparatuses, the moving speed of the sample is made variable by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. It is characterized by the following.

In this three-dimensional shape measuring apparatus, since the moving speed of the sample is variable, for example, for a sample whose surface shape changes drastically, the moving speed of the sample is reduced, and the surface shape is finished with high precision. For a sample that exhibits a gradual change in shape, measurement can be performed under optimum conditions according to the sample, such as increasing the moving speed of the sample.

Alternatively, even within a single sample, the moving speed can be changed depending on the position, such as slow in a place where the shape change is severe and fast in a gentle place, so that measurement can be performed under the optimum conditions over the entire surface of the sample. Will be possible.

A thirty-fourth three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the eighteenth three-dimensional shape measuring devices to the twenty-fifth three-dimensional shape measuring devices, moving the sample at a constant speed by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. It is characterized by the following.

In this three-dimensional shape measuring apparatus, since the moving speed of the sample is fixed, stable control can be performed even when the sample becomes large.

A thirty-fifth three-dimensional shape measuring apparatus according to the present invention comprises:
The thirty-third three-dimensional shape measuring device or the thirty-fourth three-dimensional shape measuring device is characterized in that the sample has a structure in which a substantially periodic structure is formed on a substrate.

In this three-dimensional shape measuring apparatus, since the sample has a structure in which a substantially periodic structure is formed on the substrate, the shape of the sample is changed in consideration of a change in the shape of the sample within one cycle. If the moving speed is determined, optimum measurement conditions can be set for the entire surface.

A thirty-sixth three-dimensional shape measuring apparatus according to the present invention comprises:
In the thirty-fifth three-dimensional shape measuring apparatus, when a position conjugate with the light beam diameter limiting means and a relative position in the optical axis direction between the sample and the sample are periodically changed, the optical axis between the light beam diameter limiting means and the sample is changed. The position conjugate with the beam diameter limiting means at which the relative position in the direction becomes 0 includes the height of the vertex of the substantially periodic structure and does not include the height of the substrate.

In this three-dimensional shape measuring apparatus, when it is sufficient to measure the vicinity of the vertex of a substantially periodic structure, the relative position in the optical axis direction between the sample and the position conjugate with the beam diameter limiting means is periodically determined. When the relative position in the optical axis direction between the light beam diameter limiting means and the sample becomes 0, the position conjugate with the light beam diameter limiting means includes the height of the vertex of the substantially periodic structure, Since it does not include the height of the substrate, the width for displacing the position conjugate with the light beam diameter limiting means can be narrowed, so that the displacement can be performed at a higher frequency.

A thirty-seventh three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the eighteenth three-dimensional shape measuring apparatus to the thirty-sixth three-dimensional shape measuring apparatus, the sample is a surface-mounted semiconductor package in which spherical bumps are arranged on the substrate substantially periodically, And the position conjugated to v _s / (2Rsi
nθ _b ) [Hz] and a frequency higher than R × [1
− (1−sin ² θ _b ) ^1/2 ]. Here, NA: numerical aperture on the sample side of the illumination optical system R: radius of the spherical surface when the bump shape is approximated by a spherical surface _vs : speed when the sample is moved at a constant speed θ _b : θ _b = (sin ⁻¹ NA ) / 2.

In this three-dimensional shape measuring apparatus, the first
From the same discussion as performed with the three-dimensional shape measuring device of No. 5,
When the return light from the sample is considered, the position conjugate with the light beam diameter limiting means is set at a frequency higher than v _s / (2R sin θ _b ) [Hz] and R × [1- (1-sin
It is desirable to displace in the direction of the optical axis with an amplitude larger than ² θ _b ) ^1/2 ].

If the measurement is performed in accordance with the frequency and amplitude of the displacement of the reference surface necessary for measuring the height of the bump apex, the measurement can be performed while shortening the measurement time and ensuring the accuracy.

A thirty-eighth three-dimensional shape measuring apparatus according to the present invention comprises:
In any one of the eighteenth three-dimensional shape measuring devices to the thirty-seventh three-dimensional shape measuring devices, the distance between the illumination optical system and the sample;
Alternatively, there is provided a means for measuring an equivalent amount.

A thirty-ninth three-dimensional shape measuring apparatus according to the present invention comprises:
The thirty-eighth three-dimensional shape measuring apparatus is characterized in that the means for measuring the distance between the illumination optical system and the sample or an equivalent amount thereof is an autofocus device.

In the configuration of the thirty-sixth three-dimensional shape measuring apparatus,
Only the relative change in the height of the vertex of each bump can be measured,
These three-dimensional shape measuring devices have a means for measuring the distance between the illumination optical system and the sample, or an equivalent amount thereof, so that the bump height can be measured. The absolute value can be obtained.

[0089]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIGS.

In FIG. 1, 1 is a white light source such as a halogen lamp, 2 is a collimator lens for forming the illumination light beam from the white light source 1 into a substantially parallel light beam, and 3 is a condenser lens.
Reference numeral 4 denotes a light beam deflecting unit that deflects the traveling direction of the illumination light beam. For example, a half mirror can be used. Reference numeral 5 denotes an objective lens, which is arranged such that the focal point of the illumination light by the condenser lens 3 coincides with the rear focal point of the objective lens 5. Reference numeral 6 denotes a light beam splitting unit that can use, for example, a half mirror, and splits an incident illumination light beam into a first light beam serving as a reference light beam and a second light beam serving as a measurement light beam in interference measurement. The light beam splitting means 6 also combines the measuring light beam reflected by the sample 7 and the reference light beam reflected by the mirror 11 into one light beam, and thus also serves as a light beam synthesizing means. In the traveling direction of the first light beam, a reference mirror 11 coupled to a piezo actuator 12 is disposed perpendicular to the optical axis. A piezo actuator driving device 16 is connected to the piezo actuator 12. On the other hand, the sample 7 placed on the stage 10 is arranged on the second light flux. The sample 7 is a substrate 8
It has a configuration in which bumps 9 are periodically formed thereon.
The stage 10 is moved x, y, z by a moving mechanism (not shown).
, And adjustment of the tilt in the three directions of θx, θy, and θz. The displacement in the x, y, and z directions can be measured by a linear scale (not shown).

Reference numeral 17 denotes an eyepiece tube, which can observe an optical image of the sample 7, and 13 denotes an imaging lens. Reference numeral 14 denotes light detecting means, the light receiving surface of which is disposed on the rear focal plane of the imaging lens 13. As the light detecting means 14, for example, a one-dimensional CCD can be used. The one-dimensional CCD is arranged so that its longitudinal direction is oriented in the y direction in the figure and its center coincides with the optical axis of the imaging lens 13. I have.
The light detecting means 14 is arranged there and connected to the signal calculating means 15 by a cable for transmitting a signal output.

The illumination light emitted from the white light source 1 is formed into a substantially parallel light beam by the collimator lens 2 and is converted into convergent light by the condenser lens 3. The illumination light converted into the convergent light enters the half mirror 4. The illumination light reflected by the half mirror 4 is focused on the rear focal point of the objective lens 5.
Therefore, the illuminating light incident on the objective lens 5 becomes a parallel light flux, exits from the objective lens 5, enters the half mirror 6, is reflected by the half mirror 6, and the second light flux is transmitted therethrough. Is divided into two.

The first light beam reflected by the half mirror 6 enters the reference mirror 11. The light beam reflected by the reference mirror 11 follows the original optical path and enters the half mirror 6 again. The second light flux transmitted through the half mirror 6 enters the sample 7. The light reflected by the sample 7 enters the half mirror 6 again.

At this time, taking one point on the optical axis as an example, as shown by a dotted line in the figure, the light from the sample 7 enters the imaging lens 13 via the objective lens 5 and An image is formed on the light receiving surface.

The light beam reflected by the reference mirror 11 and the light beam reflected by the sample 7 are matched again by the half mirror 6, and
Cause interference. The intensity of the interference fringes is detected by the light detecting means 14.

Hereinafter, the measurement procedure will be described: Stage 1
The sample 7 is placed on the substrate 8 and the stage 10 is parallelized on the upper surface of the substrate 8 using a tilting mechanism. After the parallel alignment of the substrate 8, the stage 10 is moved while observing with the eyepiece tube 17 so that the bump 9 of the sample 7 does not exist at the center of the visual field of the objective 5.
To move. In this state, the position of the reference mirror 11 in the optical axis direction is displaced by changing the voltage applied from the piezo actuator driving device 16. One-dimensional CC
Measuring the output of the pixel of the center of the D14, the position of the reference mirror 11 showing the maximum value (a I ₀₎ and x _0, I ₀ and x
₀ is stored in the signal calculation means 15. This position is the position where the optical path length difference between the reference mirror 11 and the substrate 8 becomes zero.

Next, the bump 9 is placed at the center of the visual field of the eyepiece tube 17.
The stage 10 is moved so that the vertex exists. In this state, the position of the reference mirror 11 in the optical axis direction is displaced, and the pixel at the center of the one-dimensional CCD 14 similarly has the maximum value (I
The position of the reference mirror 11 showing a ₁ to) as x _1,
I ₁ and x ₁ are stored in the signal calculation means 15. This position is where the optical path length difference between the reference mirror 11 and the vertex of the bump 9 becomes zero. At the time of observation of the eyepiece tube 17, observation is performed in a state in which a light beam incident on the reference mirror 11 from the half mirror 6 is shielded by a light beam shielding mechanism (not shown).
Is returned to the state where the light beam is incident.

Next, the sample 7 is moved to a position where measurement is started.
Let Reference mirror 11₀To x ₁Sine between positions
The sample 7 is moved by the stage 10 while being vibrated in a wave form.
Move in the x direction at a constant speed.

Actually, since the substrate 8 has undulations, the upper surface of the substrate 8 has irregularities, and the bumps 9 vary in size due to manufacturing errors and the like. The movement range of the reference mirror 11 is x ₀ and x
_It needs to be slightly wider, not just between ₁ .

At this time, the signal operation means 15
From a plurality of one-dimensionally arranged CCD pixels of the output means 14
Is transmitted. Here, for simplicity, multiple CCs
The following description focuses on one of the D pixels. FIG.
And the measuring light when the reference mirror 11 is displaced in a sine wave shape
5 shows a locus at a position where the optical path length difference between the light flux and the reference light flux becomes zero.
The light exits near the point where the optical path difference between the reference light beam and the measurement light beam becomes zero.
Strengthens. The point where the optical path length difference becomes 0 is small in the figure.
Distributed as circled. Output from light detection means 14
When a certain threshold is exceeded, the stage 10 at that point
And the drive voltage of the piezo actuator 12
The pressure is stored in the signal calculation means 15. Stage 10 x
The position in the direction is attached to, for example, a stage drive mechanism (not shown).
It can be measured on the added linear scale. Piezo
The drive voltage of the actuator 12 and the corresponding displacement
If measured in advance, the reference mirror 11
Of the sample 7 can be calculated based on the displacement.
Direction displacement can be calculated. The threshold value is recorded in the signal operation means 15.
I remembered₀And I₁Is determined based on Substrate 8 and bump 9
The contrast of the interference fringes
And as a result I₀And I ₁Are often different. There
So, for example, I₀And I₁And multiply the smaller value by 0.9
If the threshold value is used as the threshold, the contrast
The shape of both the substrate 8 and the bump 9 is measured even if the
Settings can be made.

In the above description, only one of the CCD pixels has been described. However, a plurality of pixels are actually arranged. When an output of a certain value or more is obtained during the measurement, the position in the y direction on the sample 7 is calculated from the information indicating which pixel has exceeded the certain value and the position of the stage 10 in the y direction at that time. be able to.

When the sample 7 is scanned in the x direction and reaches the end of the sample 7, the scanning in the x direction is stopped, the sample 7 is moved in the y direction by the scan width of measurement, and the stage 10 is again moved in the x direction. Move. By repeating this, the entire surface of the sample 7 is measured.

According to the present embodiment, the stage 10 may be moved at a constant speed during the measurement, and there is no need to repeatedly move and stop as in the conventional method. Further, since it is not necessary to measure the same portion a plurality of times, the measurement time can be significantly reduced.

In the above description, an example in which the present invention is applied to a Michelson-type white interferometer is described. However, the present invention is not limited to this, and other configurations such as a linear-type white interferometer and a Mirrow-type white interferometer can be used. It may be applied to a white light interferometer.

In the above description, as a means for detecting the displacement of the reference mirror 11, a method of calculating from the drive voltage of the piezo actuator 12 is used. However, the present invention is not limited to this. A vessel may be used. In that case, the displacement may be measured by irradiating the back surface of the reference mirror 11 with a laser by using the reference mirror 11 whose back surface is also machined.

In the above description, an example in which a halogen lamp is used as the light source 1 has been described. However, the present invention is not limited to this, and another white light source such as a xenon lamp or a mercury lamp may be used. , A light source having a low coherence, for example, an SLD (super luminescent diode) or the like may be used.

[Second Embodiment] A second embodiment of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIG.
In FIG. 2, members that are the same as or correspond to the basic configuration shown in FIG. 1 are given the same reference numerals, and descriptions thereof are basically omitted.

In FIG. 2, reference numeral 18 denotes a light beam splitting means and a light beam synthesizing means. For example, a half mirror can be used. Second light beam
And the light flux. In the traveling direction of the first light beam, a lens 21 and a reference mirror 11 coupled to a piezo actuator 12 are arranged perpendicular to the optical axis. The lens 21 is arranged such that the rear focal position coincides with the focal point of the illumination light by the condenser lens 3. On the other hand, the second
The sample 7 placed on the objective lens 20 and the stage 10 is disposed on the light beam. The objective lens 20 is arranged such that the rear focal position coincides with the focal point of the illumination light by the condenser lens 3. Lens 21 and objective lens 2
For 0, those having the same optical performance such as the focal length and the numerical aperture are used. The sample 7 has a configuration in which bumps 9 are periodically formed on a substrate 8.

An auto-focusing device indicated by reference numeral 22 disposed between the half mirror 18 and the imaging lens 13 can measure the displacement of the sample 7.
The autofocus device of the microscope is a known technique, and thus the description is omitted.

Hereinafter, the measurement procedure will be described. After the substrate 8 is set in parallel, the stage 10 is moved so that the bump 9 does not exist at the center of the visual field of the objective lens 20 while observing with the eyepiece mirror 17. In this state, the height of the substrate 8 is measured by the autofocus device 22. Sample 7
And the shape of the upper surface of the substrate 8 is approximated by applying the least square method to the plurality of results.

Next, the bump 9 is placed at the center of the visual field of the eyepiece tube 17.
The stage 10 is moved so that the vertex exists. In this state, the position of the reference mirror 11 in the optical axis direction is displaced, and the output of the pixel at the center of the one-dimensional CCD 14 becomes the maximum value (I
The position of the reference mirror 11 showing a ₃ to) as x _2,
I ₃ and x ₂ are stored in the signal calculation means 15. This position is where the optical path length difference between the reference mirror 11 and the vertex of the bump 9 becomes zero. Thereafter, the height of the apex of the bump 9 and the height of the upper surface of the substrate 8 immediately beside the bump 9 are measured by the autofocus device 22 and stored in the signal calculation means 15. When observing the eyepiece tube 17, observation is performed in a state where a light beam incident on the reference mirror 11 from the half mirror 18 is shielded by a shielding plate (not shown). Return to the state where the light beam enters.

Next, the sample 7 is moved to a position where measurement is started. In a state where the reference mirror 11 is vibrated in a sine wave shape,
Sample 7 is moved in the x direction at a constant velocity v _s by the stage 10.

At this time, the reference mirror 11_TwoAnd x_Two
−R × [1- (1-sin^Twoθ_b) ^1/2] Between
Wave number v_s/ (2R sin θ_b) Vibration at [Hz]
(In the figure, the direction of the arrow is defined as + on the x-axis.) Where: NA: numerical aperture on the sample side of the objective lens R: radius of the spherical surface when the bump shape is approximated by a spherical surface v_s: Speed at which the sample is moved at a constant speed θ_b: Θ_b= (Sin^-1NA) / 2.

Actually, since the substrate 8 has undulations, the upper surface of the substrate 8 has irregularities, and the bumps 9 vary in size due to manufacturing errors and the like. The moving range of the reference mirror 11 needs to be slightly wider than the above value.

At this time, by performing the same signal processing as in the first embodiment, the shape measurement around the apex of the bump 9 can be performed. At this time, since the range for displacing the reference plane is near the vertex of bump 9 as described above, the threshold value is
The determination is made based on I ₃ stored in the signal operation means 15. For example, a value obtained by multiplying the value of I ₃ by 0.9 may be used as the threshold.

However, only the relative measurements of the heights of the vertices of the bumps 9 can be known from the measurements so far.
The absolute value of the height from the substrate 8 to the vertex of the bump 9 cannot be calculated. Therefore, the height of one bump 9 can be calculated from the measurement result (the height of the top of the bump 9 and the height of the upper surface of the substrate 8 immediately beside the bump 9) by the autofocus device 22. The height of each bump 9 can be calculated from the relative positional relationship between the heights of the vertices of each bump 9 based on the bump 9. At this time, the influence of the unevenness due to the warpage or the like of the upper surface of the substrate 8 may be corrected for each bump 9 using a value approximating the upper surface of the substrate 8 from the measurement result by the autofocus.

When the sample 7 is scanned in the x direction and reaches the end of the sample 7, the scanning in the x direction is stopped, the sample 7 is moved in the y direction by the scan width of the measurement, and the stage 1 is again moved in the x direction.
Move 0. By repeating this, the entire surface of the sample 7 is measured.

In many cases, the reflectance of the substrate 8 differs greatly from that of the bumps 9, and the contrast of the interference fringes from the substrate 8 greatly differs from the contrast of the interference fringes generated by the bumps 9. In many cases, it was difficult to set a sensitivity suitable for both. According to the present embodiment, only the interference fringes generated at the bumps 9 need to be detected, and the sensitivity of the light detection means 14 can be adjusted to an optimum value. Further, since the amplitude at which the reference mirror 11 vibrates is reduced, the frequency at which the reference mirror 11 is displaced can be increased. Therefore, the measurement interval when measuring the sample 7 can be narrowed, and the measurement accuracy can be improved. Alternatively, by raising the stage speed v _s, it is possible to further shorten the measurement time.

In the above description, the case where the reference mirror 11 is displaced at a constant cycle has been described. However, the present invention is not limited to this. For example, the cycle may be delayed except when measuring the bump 9.

[0120] In the above description, the description has been given of the case of moving the stage 10 at a constant speed v _s, not limited to this. Since the bumps 9 are arranged regularly, the moving speed of the stage 10 is increased in an area where no bumps exist, for example, between bumps in one chip or in a chip adjacent to the chip. Therefore, the speed can be controlled to be constant at the time of measuring the bump 9, and the average moving speed of the stage 10 can be improved.
This leads to a reduction in measurement time.

[Third Embodiment] A third embodiment of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIG.
3, members that are the same as or correspond to the basic configuration shown in FIG. 1 are denoted by the same reference numerals, and description thereof is basically omitted.

In FIG. 3, 31 is a white light source such as a mercury lamp, 32 is a collimator lens for shaping the illumination light beam from the white light source 31 into a substantially parallel light beam, and 33 is a light beam deflecting means for deflecting the traveling direction of the illumination light beam. Yes, for example, a half mirror can be used. 34 is a condenser lens,
Reference numeral 35 denotes a light beam diameter restricting means, for example, a slit can be used, and the slit is arranged so that the longitudinal direction of the slit coincides with the y-axis direction. A light beam diameter restricting means 35 is disposed at a position of a focal point of the illumination light by the condenser lens 34. Numeral 36 denotes an image forming lens, which has a rear focal point and a light beam diameter limiting means 35.
And are arranged so as to match. Reference numeral 17 denotes an eyepiece tube, from which an optical image of the sample 7 can be observed. Reference numeral 37 denotes an objective lens.

The lens 38 forms a relay lens 39 together with the lens 34. The lens 34 and the light beam diameter limiting means 35 are integrally fixed by a mechanical part (not shown) to form a unit 40, which is movable in the z direction by a moving mechanism (not shown) using a piezo actuator. The displacement of the unit 40 in the optical axis direction can be calculated from the relationship between the drive voltage and the displacement by measuring the drive voltage to the piezo actuator.

The illumination light emitted from the white light source 31 is shaped into a substantially parallel light beam by the collimator lens 32 and enters the half mirror 33. The illumination light reflected by the half mirror 33 is converted into convergent light by the lens 34 and condensed at the position of the light beam diameter limiting means 35. The illuminating light passing through the slit of the light beam diameter limiting means 35 enters the imaging lens 36 to become a parallel light beam, and enters the objective lens 37. The illumination light is collected by the objective lens 37 and illuminates the sample 7.

The light beam reflected by the sample 7 again enters the half mirror 33 via the objective lens 37, the imaging lens 36, the light beam diameter limiting means 35, and the lens 34. The light beam transmitted through the half mirror 33 is collected on the light receiving surface of the light detecting means 14 by the relay lens 39.

The measurement procedure will be described below. After the sample 7 is parallelized on the upper surface of the substrate 8, while observing with the eyepiece tube 17, the bump 9 of the sample 7 should not be present at the center of the visual field of the objective lens 37. The stage 10 is moved. In this state, the position of the unit 40 in the optical axis direction is displaced by a moving mechanism (not shown). The output of the pixel at the center of the one-dimensional CCD 14 is measured, the position in the optical axis direction showing the maximum value (I ₄ ) is set to z _0, and I ₄ and z ₀ are stored in the signal calculation means 15. This position is a state where the focus is on the upper surface of the substrate 8.

Next, the bump 9 is placed at the center of the visual field of the eyepiece tube 17.
The stage 10 is moved in the x and y directions so that the vertex exists. In this state, the position of the unit 40 in the optical axis direction is displaced by a moving mechanism (not shown) to
When the output of D14 center of the pixel of a maximum value (a I _5), the position of the optical axis of the unit 40 as z _1, and stores the I ₅ and z ₁ to the signal calculation means 15. This position is a state where the apex of the bump 9 is focused.

Next, the sample 7 is moved to a position where measurement is started. The sample 7 is moved in the x direction at a constant speed by the stage 10 while the unit 40 is vibrated in a sine wave shape between z ₀ and z ₁ .

In practice, the substrate 8 has undulations,
And that there is unevenness on the substrate 8 top, since there are variations in the size of the bump 9 due to a manufacturing error or the like, in order to cope with them, the moving range of the unit 40 not only between z ₀ and z ₁ , Need to be slightly wider.

At this time, signals from a plurality of one-dimensionally arranged CCD pixels of the light detecting means 14 are transmitted to the signal calculating means 15. Here, by performing the same signal processing as in the first embodiment, the surface shape of the sample 7 can be calculated. However, when calculating the displacement of the focusing position on the sample 7 from the displacement of the unit 40, it is necessary to consider the longitudinal magnification of the optical system composed of the objective lens 37 and the imaging lens 36.

The threshold value is calculated based on the I value stored in the signal operation means 15.
₄ and I ₅ is determined based on. Due to the difference in reflectance between the substrate 8 and the bump 9, the light intensities I ₄ and I ₅
Are often different. Therefore, as described in the first embodiment, for example, if the smaller one of I ₄ and I ₅ is multiplied by 0.9, and the threshold is set as the threshold, the reflectance of the sample 7 depends on the location. Even if different, the shape measurement of both the substrate 8 and the bump 9 can be performed.

When the sample 7 is scanned in the x direction and reaches the end of the sample 7, the scanning in the x direction is stopped, the sample 7 is moved in the y direction by the scan width of the measurement, and the stage 10 is again moved in the x direction. Move. By repeating this, the entire surface of the sample 7 is measured.

According to the present embodiment, the stage 10 may be moved at a constant speed during measurement, and there is no need to repeatedly move and stop as in the conventional method. Further, since it is not necessary to measure the same portion a plurality of times, the measurement time can be significantly reduced.

In the above description, the case where the aperture shape is a slit as the light beam diameter limiting means 35 has been described. However, the present invention is not limited to this, and another shape such as a pinhole may be used. In this case, the beam diameter limiting means 35 and the sample 7
It is necessary to add a mechanism for scanning the illumination light beam in the y-direction between the two, and if the mechanism becomes complicated, the measurement time becomes long. However, in the above embodiment using the slit, the confocal effect can be obtained only in two directions of x and z, and y
With respect to the direction, only a resolution equivalent to that of a normal microscope can be obtained, while using a pinhole has the advantage that a confocal effect can be obtained in all directions of x, y, and z.

In the above description, an example in which a mercury lamp is used as the light source 31 has been described. However, the present invention is not limited to this, and another white light source, for example, a xenon lamp may be used, or a laser light source, for example, helium. A neon laser or the like may be used.

[Fourth Embodiment] A fourth embodiment of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIG.
In FIG. 4, members that are the same as or correspond to the basic configuration shown in FIGS. 1 to 3 are given the same reference numerals, and description thereof is basically omitted.

In FIG. 4, reference numeral 41 denotes a light beam diameter restricting means, for example, a multi-pinhole array can be used, and it is rotatable about a z-axis by a mechanism (not shown). The light beam diameter limiting means 41 is
4 is disposed at the position of the focal point of the illumination light. An objective lens 42 is movable in the z direction by a moving mechanism (not shown) using a piezo actuator.
The displacement of the objective lens 42 in the optical axis direction can be calculated from the relationship between the drive voltage and the displacement by measuring the drive voltage to the piezo actuator.

Hereinafter, the measurement procedure will be described. After the substrate 8 is set in parallel, the stage 10 is moved while observing with the eyepiece tube 17 so that the bump 9 does not exist at the center of the visual field of the objective lens 42. In this state, the height of the substrate 8 is measured by the autofocus device 22. Sample 7
And the shape of the upper surface of the substrate 8 is approximated by applying the least square method to the plurality of results.

Next, the bump 9 is placed at the center of the visual field of the eyepiece tube 17.
The stage 10 is moved so that the vertex exists. In this state, the position of the objective lens 42 in the optical axis direction is displaced, and the output of the pixel at the center of the one-dimensional CCD 14 becomes the maximum value (I
As z ₃ the position of the objective lens 42 showing the to) and _6,
I ₆ and z ₃ are stored in the signal calculation means 15. This position is the position where the apex of the bump 9 is focused. Thereafter, the height of the apex of the bump 9 and the height of the upper surface of the substrate 8 immediately beside the bump 9 are measured by the autofocus device 22 and stored in the signal calculation means 15.

Next, the sample 7 is moved to a position where measurement is started. With the objective lens 42 vibrated in a sine wave shape,
Sample 7 is moved in the x direction at a constant velocity v _s by the stage 10.

At this time, the objective lens 42 has z ₃ and z ₃ −
Between the R × _{^{[1- (1-sin 2 θ b}} ) 1/2 ], (in the figure to oscillate at a frequency v _s / (2Rsinθ _b) [Hz], in the figure, the arrow direction x-axis of the + .). Where: NA: numerical aperture on the sample side of the objective lens R: radius of the spherical surface when the bump shape is approximated by a spherical surface v _s : speed when the sample is moved at a constant speed θ _b : θ _b = (sin ⁻¹ NA) / 2.

Actually, since the substrate 8 has undulations,
Since the bumps 9 have irregularities on the upper surface of the substrate 8 and variations in the size of the bumps 9 due to manufacturing errors and the like, the moving range of the objective lens 42 needs to be slightly wider than the above value in order to cope with these. is there.

At this time, by performing the same signal processing as in the second embodiment, the shape measurement around the vertex of the bump 9 can be performed. At this time, the displacement of the objective lens 42 and the accompanying displacement of the focus position on the sample 7 are equal. Therefore, by measuring the displacement of the objective lens 42,
The displacement at a position conjugate with the light beam diameter limiting means 41 can be obtained. Since the position conjugate with the beam diameter limiting means 41 is only near the vertex of the bump 9 as described above, the threshold value is determined based on I ₆ stored in the signal calculating means 15. For example, a value obtained by multiplying the value of I ₆ by 0.9 may be used as the threshold.

However, only by this, the relative positional relationship between the vertices of the bumps 9 can be known, and the absolute value of the height from the substrate 8 to the vertices of the bumps 9 cannot be calculated. Then, the measurement result by the autofocus device 22 (the height of the bump 9 apex and the height of the upper surface of the substrate 8 immediately beside)
Thus, the height can be calculated for one bump 9. The height of each bump 9 can be calculated from the relative positional relationship between the heights of the vertices of each bump based on the bump 9. At this time, the influence of unevenness due to the warpage of the upper surface of the substrate 8 may be corrected for each bump 9 using a value obtained by approximating the upper surface of the substrate 8 based on the measurement result of the autofocus device 22.

When the sample 7 is scanned in the x direction and reaches the end of the sample 9, the scanning in the x direction is stopped, the sample 7 is moved in the y direction by the scan width of the measurement, and the stage 10 is again moved in the x direction. Move. This is repeated to measure the entire surface of the sample.

According to the present embodiment, the light beam diameter limiting means 4
Since a multi-pinhole array is used as 1, z
A confocal effect is obtained not only in the axial direction but also in the x and y directions, and high-resolution measurement can be performed.

In many cases, the reflectance of the substrate 8 differs greatly from that of the bumps 9, and the amount of light applied to the light detecting means 14 differs greatly between the light reflected from the substrate 8 and the light reflected from the bumps 9. It has often been difficult to set the means 14 to a sensitivity suitable for both. According to the present embodiment, only the reflected light from the bump 9 needs to be detected, and the sensitivity of the light detecting means 14 can be adjusted to an optimum value. Further, since the amplitude at which the objective lens 42 is vibrated is reduced, the frequency at which the objective lens 42 is displaced can be increased. Therefore, the measurement interval when measuring the sample 7 can be narrowed, and the measurement accuracy can be improved. Alternatively, by raising the stage speed v _s, it is possible to further shorten the measurement time.

In the above description, the case where the objective lens 42 is displaced at a constant cycle has been described. However, the present invention is not limited to this. For example, the cycle may be delayed except for bump measurement.

[0149] In the above description, the description has been given of the case of moving the stage 10 at a constant speed v _s, not limited to this. Since the bumps 9 are arranged regularly, the moving speed of the stage 10 in an area where no bumps exist, for example, between bumps in one chip or between a chip and an adjacent chip. The average moving speed of the stage 10 can be improved by controlling the speed to be constant at the time of bump measurement, thereby leading to a reduction in measurement time.

In the above description, as a means for detecting the displacement of the objective lens 42, a method of calculating from the drive voltage of the piezo actuator is used. However, the present invention is not limited to this, and other means, such as a laser length measuring device, may be used. May be used. In that case, mechanical parts (not shown) supporting the objective lens 42
A mirror may be attached to a part of the mirror, and the displacement may be measured by a laser length measuring device using the mirror surface.

The three-dimensional shape measuring apparatus of the present invention described above can be constituted, for example, as follows.

[1] A light source for generating illumination light having low coherence, a light beam splitting means for splitting the illumination light into a reference light beam incident on the reference surface and a measurement light beam incident on the sample,
An illumination optical system that focuses the illumination light on the sample, a light beam combining unit that combines the reference light beam and the measurement light beam, a unit that moves the sample in a direction perpendicular to the optical axis of the illumination optical system, Means for detecting a position in a plane perpendicular to the optical axis of the illumination optical system or an equivalent amount thereof, and detecting an optical path length difference between the reference light beam and the measurement light beam, or an amount equivalent to the optical path length difference , A light detecting means, and a signal calculating means for calculating a signal detected by the light detecting means. In a state where the sample is moving in a direction perpendicular to the optical axis of the illumination optical system, A three-dimensional shape measuring apparatus characterized in that a signal is detected by a detecting means.

[2] In the above item 1, the signal calculation means includes means for setting a threshold value, means for comparing a signal from the light detection means with the threshold value, and a signal exceeding the threshold value. A means for storing the optical path length difference and a position of the sample in a plane perpendicular to the optical axis of the illumination optical system; and a means for calculating the shape of the sample from information in the storage means. Dimensional shape measuring device.

[3] The three-dimensional shape measuring apparatus according to the above item 1 or 2, wherein the light detecting means is a one-dimensional line sensor.

[4] The three-dimensional shape measuring apparatus according to the above item 3, wherein the one-dimensional line sensor is a one-dimensional CCD.

[5] The three-dimensional shape measuring apparatus according to any one of the above items 1 to 4, further comprising means for periodically changing an optical path length difference between the reference light beam and the measuring light beam.

[6] The three-dimensional shape measuring apparatus according to the above item 5, wherein the means for periodically changing the optical path length difference between the reference light beam and the measuring light beam has a variable period for changing the optical path length. .

[7] In the above-mentioned item 5 or 6, the means for periodically changing the optical path length difference between the reference light beam and the measurement light beam has a mechanism for displacing the reference surface in the optical axis direction. Dimensional shape measuring device.

[8] In the above item 7, the means for detecting the optical path length difference between the reference light beam and the measuring light beam or the amount equivalent to the optical path length difference includes the means for detecting the displacement of the reference surface in the optical axis direction. A three-dimensional shape measuring device characterized by having:

[0160]

[9] The three-dimensional shape measuring apparatus according to the above item 8, wherein the means for detecting the displacement of the reference surface in the optical axis direction is a laser length measuring device.

[10] In the above 7, the mechanism for displacing the reference surface in the optical axis direction is a piezo actuator, and detects a difference in optical path length between the reference light beam and the measuring light beam or an amount equivalent to the optical path length difference. 3. The three-dimensional shape measuring apparatus as claimed in claim 1, wherein the means for performing includes a means for detecting a driving voltage of the piezo actuator.

[11] In any one of the above items 1 to 10, the moving speed of the sample is made variable by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. 3D shape measuring device.

[12] The method according to any one of the above items 1 to 10, wherein the sample is moved at a constant speed by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. Dimensional shape measuring device.

[13] The three-dimensional shape measuring apparatus according to the above item 11 or 12, wherein the sample has a structure in which a substantially periodic structure is formed on a substrate.

[14] In the above item 13, the optical path length difference between the reference light beam and the measurement light beam is 0 when the reference surface is displaced.
Wherein the position on the measuring light beam includes the height of the vertex of the substantially periodic structure and does not include the height of the substrate.
Dimensional shape measuring device.

[15] In any one of the above items 1 to 14, the sample is a surface mount type semiconductor package in which spherical bumps are arranged on the substrate substantially periodically, and the reference surface is v
_{At a} frequency higher than _s / (2R sin θ _b ) [Hz],
A three-dimensional shape measuring apparatus characterized in that the amplitude is changed in the optical axis direction with an amplitude larger than R × [1- (1-sin ² θ _b ) ^1/2 ]. Here, NA: numerical aperture on the sample side of the illumination optical system R: radius of the spherical surface when the bump shape is approximated by a spherical surface _vs : speed when the sample is moved at a constant speed θ _b : θ _b = (sin ⁻¹ NA ) / 2.

[16] A three-dimensional shape measuring apparatus according to any one of the above items 1 to 15, further comprising means for measuring a distance between the illumination optical system and the sample or an equivalent amount thereof.

[17] The three-dimensional shape measuring apparatus according to the above item 16, wherein the means for measuring the distance between the illumination optical system and the sample or an equivalent amount thereof is an autofocus device.

[18] A light source for generating illumination light, an illumination optical system for condensing the illumination light on the sample, an imaging optical system for forming an image of light from the sample, and a position conjugate with the sample Beam diameter limiting means, a relative position in the optical axis direction of the sample and a position conjugate with the light beam diameter limiting means, or a means for detecting an equivalent amount thereof, and the sample with respect to the optical axis of the illumination optical system. Means for moving the sample in a direction perpendicular to the optical axis of the sample, a means for detecting a position in a plane perpendicular to the optical axis of the illumination optical system, or an equivalent amount thereof, a light detecting means, and a light detecting means. Signal calculation means for calculating the detected signal, wherein the signal is detected by the light detection means while the sample is moving in a direction perpendicular to the optical axis of the illumination optical system. Dimensional shape measuring device.

[19] In the above item 18, the signal calculation means may include a means for setting a threshold value, a means for comparing a signal from the light detection means with the threshold value, and a signal exceeding the threshold value. Relative position in the optical axis direction of the sample and the position conjugate with the beam diameter limiting means, or an equivalent amount thereof,
A three-dimensional shape measuring apparatus comprising: means for storing a position of a sample in a plane perpendicular to the optical axis of an illumination optical system; and means for calculating the shape of the sample from information in the storage means. .

[20] The three-dimensional shape measuring apparatus according to the above item 18 or 19, wherein the light detecting means is a one-dimensional line sensor.

[21] The three-dimensional shape measuring apparatus according to the above item 20, wherein the one-dimensional line sensor is a one-dimensional CCD.

[22] The three-dimensional shape measuring apparatus according to the above item 18 or 19, wherein the light beam diameter limiting means is a pinhole.

[23] A three-dimensional shape measuring apparatus according to any one of the above items 18 to 21, wherein the light beam diameter limiting means is a slit.

[24] The three-dimensional shape measuring apparatus according to any one of the above items 18 to 21, wherein the light beam diameter limiting means is a multi-pinhole array.

[25] The method according to any one of the above items 18 to 24, further comprising means for periodically changing a position conjugate with the light beam diameter limiting means and a relative position in the optical axis direction with respect to the sample. Three-dimensional shape measuring device.

[26] In the above item 25, the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position in the optical axis direction with respect to the sample is provided by periodically changing the position of the light beam diameter limiting means. A three-dimensional shape measuring device having a mechanism for causing the three-dimensional shape to be measured.

[27] In the above item 26, the position conjugate with the light beam diameter limiting means and the relative position of the sample with respect to the optical axis direction,
Alternatively, the three-dimensional shape measuring apparatus is characterized in that the means for detecting the equivalent amount includes means for detecting the position of the light beam diameter limiting means. [28] In the above item 25, the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position of the sample in the optical axis direction has a mechanism for periodically changing the position of the illumination optical system. Characterized by 3
Dimensional shape measuring device.

[29] In the above item 28, the position conjugate with the light beam diameter limiting means and the relative position of the sample with respect to the optical axis direction,
Alternatively, the three-dimensional shape measuring device is characterized in that the means for detecting the equivalent amount includes means for detecting the position of the illumination optical system.

[30] In the above item 25, the means for periodically changing the position conjugate with the light beam diameter limiting means and the relative position in the optical axis direction with respect to the sample periodically changes the position of the imaging optical system. A three-dimensional shape measuring device having a mechanism for causing the three-dimensional shape to be measured.

[31] In the above item 30, the position conjugate with the beam diameter limiting means and the relative position of the sample with respect to the optical axis direction,
Alternatively, the three-dimensional shape measuring apparatus is characterized in that the means for detecting the equivalent amount includes means for detecting the position of the imaging optical system.

[32] In the above item 25, in the means for periodically changing the relative position in the optical axis direction between the sample and the position conjugate with the light beam diameter limiting means, the period is variable. Dimensional shape measuring device.

[33] In any one of the above items 18 to 25, the moving speed of the sample is made variable by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system. 3D shape measuring device.

[34] The three-dimensional shape measuring apparatus according to any one of the above items 18 to 25, wherein the sample is moved at a constant speed by means for moving the sample in a direction perpendicular to the optical axis of the illumination optical system.

[35] The three-dimensional shape measuring apparatus according to the above item 33 or 34, wherein the sample has a structure in which a substantially periodic structure is formed on a substrate.

[36] In the above item 35, when the position conjugate with the light beam diameter limiting means and the relative position in the optical axis direction between the sample and the sample are periodically changed, the optical axis between the light beam diameter limiting means and the sample is changed. A three-dimensional shape measuring apparatus characterized in that the position conjugate with the beam diameter limiting means at which the relative position in the direction becomes 0 includes the height of the vertex of the substantially periodic structure and does not include the height of the substrate. .

[37] In any one of the above items 18 to 36, the sample is a surface mount type semiconductor package in which spherical bumps are arranged on the substrate substantially periodically, and a position conjugate with the light beam diameter limiting means is determined. v _s / (2R sin θ _b ) [H
z], and R × [1- (1-si
A three-dimensional shape measuring apparatus characterized in that it is displaced in the direction of the optical axis with an amplitude larger than n ² θ _b ) ^1/2 ]. Here, NA: numerical aperture on the sample side of the illumination optical system R: radius of the spherical surface when the bump shape is approximated by a spherical surface _vs : speed when the sample is moved at a constant speed θ _b : θ _b = (sin ⁻¹ NA ) / 2.

[38] The three-dimensional shape measuring apparatus according to any one of the above items 18 to 37, further comprising means for measuring a distance between the illumination optical system and the sample or an equivalent amount thereof.

[39] The three-dimensional shape measuring apparatus according to the above item 38, wherein the means for measuring the distance between the illumination optical system and the sample or the equivalent amount thereof is an autofocus device.

[0190]

As described above, according to the present invention, in a measuring method such as a white light interferometer or a confocal microscope, it is possible to measure the three-dimensional shape of a sample without measuring the same portion a plurality of times. Yes, high measurement throughput can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the configuration and operation of a three-dimensional shape measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the configuration and operation of a three-dimensional shape measuring apparatus according to a second embodiment.

FIG. 3 is a diagram for explaining the configuration and operation of a three-dimensional shape measuring apparatus according to a third embodiment.

FIG. 4 is a diagram for explaining the configuration and operation of a three-dimensional shape measuring apparatus according to a fourth embodiment.

FIG. 5 is a diagram illustrating a trajectory of a position where the optical path length difference between the measurement light beam and the reference light beam becomes zero when the sample is moved at a constant speed and the reference mirror is displaced in a sine wave shape in the first embodiment.

FIG. 6 is a diagram illustrating a relationship between an optical path length difference and interference intensity in interference measurement using low coherence light.

FIG. 7 is a diagram schematically showing a state in which reflected light from the periphery cannot be captured by an optical system in the case of a hemispherical sample.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... White light source 2 ... Collimator lens 3 ... Condensing lens 4 ... Light beam deflecting means (half mirror) 5 ... Objective lens 6 ... Light beam splitting means (half mirror) 7 ... Sample 8 ... Substrate 9 ... Bump 10 ... Stage 11 ... See Mirror 12 Piezo actuator 13 Imaging lens 14 Photodetector (one-dimensional CCD) 15 Signal calculator 16 Piezoactuator driving device 17 Eyepiece tube 18 Beam splitting device (half mirror) 20 Objective lens 21 ... Lens 22 ... Autofocusing device 31 ... White light source 32 ... Collimator lens 33 ... Light flux deflecting means (half mirror) 34 ... Condensing lens 35 ... Light flux diameter limiting means (slit) 36 ... Imaging lens 37 ... Objective lens 38 ... Lens 39: relay lens 40: scan unit 41: beam diameter limiting means (multi-pinhole) Array 42) Objective lens

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA06 AA24 AA53 BB05 CC26 DD06 FF10 FF52 GG02 GG05 GG12 HH13 JJ02 JJ25 LL00 LL04 LL28 LL30 LL46 PP12 PP22 PP24 QQ18 UU05 UU06 UU07

Claims (2)

[Claims] A light source for generating illumination light having low coherence; a light beam splitting means for splitting the illumination light into a reference light beam incident on a reference surface and a measurement light beam incident on the sample; An illumination optical system that emits light; a light beam combining unit that combines a reference light beam and a measurement light beam; a unit that moves a sample in a direction perpendicular to the optical axis of the illumination optical system; and an optical axis of the sample illumination optical system Means for detecting a position in a plane perpendicular to or a quantity equivalent thereto, means for detecting a difference in optical path length between the reference light flux and the measurement light flux, or a quantity equivalent to the difference in optical path length, and light detection. Means for calculating a signal detected by the light detecting means, and detecting the signal by the light detecting means while the sample is moving in a direction perpendicular to the optical axis of the illumination optical system. A three-dimensional shape measuring apparatus. 2. A light source for generating illumination light, an illumination optical system for condensing the illumination light on the sample, an imaging optical system for imaging light from the sample, and a position near a position conjugate with the sample. Means for detecting a relative position in the optical axis direction of the sample and a position conjugate with the light beam diameter restricting means or an equivalent amount thereof, and a method of positioning the sample with respect to the optical axis of the illumination optical system. Means for moving in a vertical direction, a position of the sample in a plane perpendicular to the optical axis of the illumination optical system,
Or a means for detecting an amount equivalent thereto, a light detecting means, and a signal calculating means for calculating a signal detected by the light detecting means, wherein the sample is arranged in a direction perpendicular to the optical axis of the illumination optical system. A three-dimensional shape measuring apparatus, wherein a signal is detected by a light detecting means while moving.