JP4790551B2 - Fine shape measuring device - Google Patents

Description

  The present invention relates to a fine shape measuring apparatus, and more particularly to an improvement of a measurement error reduction mechanism thereof.

Conventionally, in order to measure the fine shape of a workpiece, a fine shape measuring device such as a scanning probe microscope has been used. An example of the scanning probe microscope is an atomic force microscope. In this method, the atomic force acting between the workpiece surface and the stylus is detected, and the workpiece surface is scanned so that the atomic force is constant, thereby grasping the unevenness of the workpiece surface. (For example, refer to Patent Document 1).
There are many methods for measuring the displacement amount of the stylus of the fine shape measuring apparatus. For example, an optical lever method using a laser and an optical sensor capable of detecting a position (see, for example, Patent Documents 1 and 2), a focus error, and the like. There are measurement by a detection method (for example, see Patent Document 3), measurement by an optical fiber interferometer (for example, see Patent Documents 4 and 5), and the like.

The optical lever system is shown in FIG. This is to irradiate the back surface of the cantilever and detect the reflected light with a position sensor located far away. When the stylus of the cantilever is displaced in the vertical direction along the unevenness of the workpiece surface, the amount of displacement is reflected in the change in angle of the reflected light. In the optical lever system, the change in angle is magnified far away and detected by the position sensor. For this reason, the change in angle of the reflected light can be detected from the light intensity signal received by the optical sensor, and the height above the workpiece surface pointed to by the stylus of the cantilever can be measured.
Further, the height on the workpiece surface can be measured by scanning the workpiece surface while relatively moving the workpiece surface up and down so that the light intensity signal of the optical sensor always becomes a predetermined value.
According to the fine shape measuring apparatus, it is possible to measure the fine shape of one line or two-dimensional area of the workpiece by grasping the height on the workpiece surface in this way.

By the way, since it is necessary for a fine shape measuring apparatus to measure a very fine shape as compared with general shape measurement, a highly accurate measurement is required.
In order to meet such a demand, various fine shape measuring apparatuses have been proposed. For example, in Patent Document 4, in order to reduce adverse effects on measurement accuracy such as twisting of the guiding means, a measuring element is provided by providing a right-angle three-sided reflector on the measuring element and measuring the amount of displacement with a plurality of displacement meters. Techniques have been proposed for grasping the amount of displacement.

JP 2002-181687 A JP 9-72924 A JP-A-9-61441 JP-A-7-301510 Japanese Patent No. 3081979

However, even with the conventional method, sufficient measurement accuracy cannot be obtained, and there is still room for further improvement.
As a result of studying this point, the present inventors found the following points. That is, when the measurement is performed by scanning the workpiece, the data obtained by the sensor that senses the height is based on the amount that the cantilever moves up and down according to the shape of the workpiece and the movement error generated by the scanning means. It was found to be the sum of the amount of
In order to reduce such a measurement error, conventionally, it is conceivable to use a high-precision scanning means with less motion error.
However, it is extremely difficult to prepare an ideal scanning means having no motion error. Even if such a scanning means can be prepared, it will be extremely expensive, making it difficult to manufacture a low-cost apparatus.
Therefore, the use of scanning means with higher accuracy has not been adopted as the problem solving means of the present invention.

Further, another conventional method, that is, one proposed to eliminate the influence of a motion error generated by the scanning means, is complicated by using a right-angle three-surface reflector as shown in Patent Document 4. Since it had to be an apparatus configuration, it could not be adopted as a problem solving means of the present invention.
As described above, in the fine shape measurement field, development of a technique capable of achieving high measurement accuracy without using a high-accuracy scanning unit has been strongly demanded. There was no suitable technology that could do that.
The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a fine shape measuring apparatus capable of performing fine shape measurement with higher accuracy.

  As a result of extensive studies by the present inventors on the improvement of the precision of the fine shape measurement, it is extremely effective to measure the vertical displacement of the stylus on the basis of a reference member whose position and posture with respect to the workpiece are fixed. The measurement is performed by scanning the surface of the workpiece while moving the cantilever fixed end up and down so that the vertical deflection amount of the cantilever based on the displacement of the cantilever fixed end detected with reference to the reference member becomes a predetermined value. Has been found to be extremely stable and highly accurate, and the present invention has been completed.

That is, the fine shape measuring apparatus according to the present invention to achieve the above object includes a cantilever, a scanning unit, a driving unit, a reference member, a free end displacement meter, a fixed end displacement meter, a calculation unit, And a control means.
Here, the cantilever has a stylus at the free end for tracing the irregularities of the workpiece surface while the fixed end is held, and has flexibility in the vertical direction.
The scanning means relatively scans the cantilever and the work surface in the lateral direction.
The driving means moves the cantilever fixed end up and down.
The reference member is provided so that the relative position and posture with respect to the workpiece do not change even by the scanning.

The free end displacement meter measures the relative displacement in the vertical direction between the reference member and the stylus and outputs free end displacement information.
The fixed end displacement meter measures the relative displacement in the vertical direction between the reference member and the cantilever fixed end substantially, and outputs fixed end displacement information.
The computing means obtains the vertical deflection amount of the cantilever based on the free end displacement information obtained by the free end displacement meter and the fixed end displacement information obtained by the fixed end displacement meter.
The control means controls the operation of the driving means and controls the vertical position of the cantilever fixed end so that the amount of deflection obtained by the calculating means becomes a predetermined value.
In the present invention, the shape of the workpiece surface is grasped based on the free end displacement information obtained by scanning the workpiece surface while moving the cantilever fixed end up and down so that the deflection amount of the cantilever becomes a predetermined value. To do.

  In the present invention, the scanning means always matches the vertical displacement axis of the stylus with the free end measurement axis of the free end displacement meter, and the vertical displacement axis of the cantilever fixed end and the Scan the workpiece and reference member with respect to the cantilever and displacement meter, or scan the cantilever and displacement meter with respect to the workpiece and reference member so that the fixed end measurement axis of the fixed end displacement meter always coincides. Is preferred.

<Light wave interferometric displacement meter>
In the present invention, the free end displacement meter is a light wave interference displacement meter, the reference member is a reference mirror of a light wave interference displacement meter, and the free end displacement meter refers to a part of coherent light. Reference light, which is reflected light from the reference mirror obtained by entering the mirror, and measurement light, which is reflected light obtained by entering the free end measurement site that is transmitted through the reference mirror and positioned on the stylus on the back surface of the cantilever And the free end displacement information based on the interference is preferably obtained.
In the present invention, the fixed end displacement meter is a light wave interference displacement meter, the reference member is a reference mirror of a light wave interference displacement meter, and the fixed end displacement meter refers to a part of coherent light. The reference light, which is reflected light from the reference mirror obtained by being incident on the mirror, and the measurement light, which is reflected light that is transmitted through the reference mirror and substantially incident on the fixed cantilever, are interfered by the reference mirror. It is preferable to obtain the fixed end displacement information based on the interference.

<Lens>
In the present invention, it is preferable that the free end light wave interference displacement meter includes a lens.
Here, the lens is scanned in the lateral direction together with the cantilever while being inserted into a coherent parallel light beam from the reference mirror. The lens converges and enters the parallel light beam on the moving end measurement site on the back surface of the cantilever, and emits the reflected measurement light on the free end measurement axis of the free end displacement meter.

<Capacitance displacement meter>
In the present invention, the fixed-end displacement meter is a capacitive displacement meter including a reference electrode and a detection electrode that are two electrodes facing each other in the vertical direction, and the reference electrode is provided on the reference member. The detection electrode is substantially provided at the fixed end of the cantilever, and the fixed-end displacement meter measures a change in capacitance between the reference electrode and the detection electrode, and detects the change in capacitance. It is preferable to obtain the fixed end displacement information based thereon.
In the present invention, the detection electrode is a ring-shaped electrode, and the ring-shaped detection electrode is arranged so that the center axis of the ring-shaped detection electrode coincides with the free end measurement axis of the free end displacement meter. It is also preferable to arrange on the free end measurement axis of the free end displacement meter.

  The term “substantially cantilever fixed end” here does not mean only the cantilever fixed end, but can be used to measure the vertical displacement of the cantilever fixed end with reference to the reference member, such as a cantilever holder. Including.

According to the fine shape measuring apparatus of the present invention, the cantilever includes the reference member, the free end displacement meter, the fixed end displacement meter, and the control means, and the cantilever deflection amount is constant. Since the workpiece surface is scanned while moving the fixed end up and down, stable and highly accurate fine shape measurement can be performed.
In the present invention, the vertical displacement axis of the stylus always coincides with the free end measurement axis of the free end displacement meter, and the vertical displacement axis of the cantilever fixed end and the fixed end of the fixed end displacement meter By performing scanning so that the measurement axis always coincides, it is possible to perform more stable and highly accurate fine shape measurement.

In the present invention, the free-end displacement meter and the fixed-end displacement meter are light wave interference displacement meters, and the reference member is a reference mirror of a light wave interference displacement meter, so that the fine shape measurement can be further performed. Stable and highly accurate.
Further, in the present invention, the free-end displacement meter is a light wave interference displacement meter, and the fixed-end displacement meter is a capacitance displacement meter. Both simplification and realization can be realized. In the present invention, the detection electrode of the capacitance displacement meter is a ring-shaped electrode, and the center axis of the ring-shaped electrode and the free end measurement axis of the free end displacement meter coincide with each other. By arranging the ring-shaped electrode on the free end measuring axis of the free end displacement meter, both stable and highly accurate fine shape measurement and simplified configuration can be realized more reliably. .

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
First Embodiment FIG. 1 shows a schematic configuration of a fine shape measuring apparatus according to an embodiment of the present invention. In this embodiment, it is assumed that the Z displacement is measured by scanning the cantilever in the X direction.
A scanning probe microscope (fine shape measuring apparatus) 10 shown in FIG. 1 includes a base plate 12, a cantilever 14, a cantilever holder 16, a scanning stage (scanning means) 18, a Z-direction drive mechanism (drive means) 20, A reference mirror (reference member) 22 of a light wave interference displacement meter, a free end displacement meter 24, a fixed end displacement meter 26, a calculation means 28, a control means 30, and an analysis means 32 are provided.

Here, the cantilever 14 has a stylus 34 for tracing the unevenness of the surface of the workpiece 40 at the free end 14a while the fixed end 14b is held, and is flexible in the Z direction (vertical direction).
The cantilever holder 16 holds the cantilever fixing end 14b.
The scanning stage 18 is provided on the base plate 12 and scans the cantilever 14 in the X direction along the surface of the workpiece 40.
The Z direction drive mechanism 20 includes an elastic hinge 42 and a piezoelectric element 44. The Z direction drive mechanism 20 moves the cantilever fixed end 14b in the Z direction. Therefore, in the present embodiment, the Z-direction drive mechanism 20 moves the cantilever holder 16 in the Z direction.

The reference mirror 22 is a reference mirror of a light wave interferometric displacement meter, and is installed on the base plate 12 so that the relative position and posture with respect to the workpiece 40 are not changed by the scanning. And almost the same size.
The free end displacement meter 24 is composed of a light wave interference displacement meter, measures the relative displacement in the Z direction between the reference mirror 22 and the stylus 34, and outputs free end displacement information.
The fixed end displacement meter 26 is a light wave interference displacement meter, measures the relative displacement in the Z direction between the reference mirror 22 and the cantilever fixed end 14b, and outputs fixed end displacement information. Therefore, in this embodiment, the relative displacement in the Z direction between the reference mirror 22 and the cantilever holder 16 is measured.
The calculation means 28 calculates the deflection amount of the cantilever 14 based on the difference between the free end displacement information obtained by the free end displacement meter 24 and the fixed end displacement information obtained by the fixed end displacement meter 26, and calculates this. Output as measured value of deflection.
The control unit 30 controls the Z position of the cantilever holder 16 by controlling the driving of the Z-direction drive mechanism 20 so that the deflection amount measurement value from the calculation unit 28 becomes the deflection amount setting value.
Based on the free end displacement information obtained by scanning the surface of the work 40 while the cantilever holder 16 is moved up and down so that the deflection amount of the cantilever 14 becomes a predetermined value by the control means 30, the analysis means 32 is uneven. To figure out.

In this embodiment, the free end displacement meter 24 includes a light source 50, a lens 52, a beam splitter 54, a beam splitter 56, a reference mirror 22, a λ / 4 plate 58, a lens 60, and a cantilever. 14 includes a free end measurement site 14c located on the stylus 34 on the back surface, and a free end phase detector 64.
Here, the lens 60 is inserted into a coherent parallel light beam, scanned in the X direction together with the cantilever 14, and converges the parallel light beam from the reference mirror 22 onto the free end measurement site 14 a on the back surface of the cantilever 14. And the measurement light which is the reflected light is emitted.
The fixed end displacement meter 26 includes one light source 50, a lens 52, a beam splitter 54, a mirror 66, a beam splitter 68, a reference mirror 22, a λ / 4 plate 58, a mirror 70, and a fixed end phase. A detection unit 72.
The moving end displacement meter 24 and the fixed end displacement meter 26 use one light source 50, a lens 52, a beam splitter 54, a reference mirror 22, and a λ / 4 plate 58 as a common optical system constituent member. .

The workpiece 40 and the reference mirror 22 are fixed on the base plate 12 and are installed so that relative displacement does not occur even by scanning.
The lens 60 is held by a lens holder 74, and the lens holder 74 and the cantilever holder 16 are fixed so as not to move with respect to each other.
The cantilever holder 16 is fixed to the Z direction driving mechanism 20, and the Z direction driving mechanism 20 is coupled to the scanning stage 18. As a result, the cantilever 14 can be moved in any direction of XYZ, that is, in the X direction in this embodiment. The moving end displacement meter 24 and the fixed end displacement meter 26 are fixed to the scanning stage 18 and are scanned in the X direction together with the cantilever 14 and the lens 60 during scanning.

The scanning probe microscope 10 according to the present embodiment is configured as described above, and the operation thereof will be described below.
In the present embodiment, by measuring the displacement of the stylus 34 in the Z direction with reference to the reference mirror 22, high-precision measurement can be performed. In this case, the surface of the workpiece 40 is scanned while moving the cantilever holder 16 so that the deflection amount of the cantilever 14 detected with reference to the reference mirror 22 becomes constant, thereby realizing more stable and highly accurate measurement. Can do.
Here, in the present embodiment, since the reference mirror 22 has a size larger than the measurement area on the surface of the workpiece 40, the Z displacement of the stylus 34 can be reliably measured with reference to the reference mirror 22.
In the present embodiment, the Z-direction displacement axis of the stylus 34 and the free-end measurement axis of the free end displacement meter 24 always coincide with each other even by scanning, and the Z-direction displacement axis and the fixed end displacement of the cantilever fixed end 14b. Since the scanning is performed so that the fixed end measurement axis of the total 26 always coincides, the ideal displacement measurement of the stylus 34 and the deflection amount measurement of the cantilever 14 can be performed without generating a cosine error.

Below, the said effect | action is demonstrated more concretely.
In this figure, the reference mirror 22 and the workpiece 40 are fixed to the base plate 12, and the displacement meters 24 and 26 including the lens 60 and the cantilever 14 are scanned in the X direction with respect to the base plate 12.
Then, the laser light (coherent light) from the light source 50 is collimated by the lens 52, and further, the beam splitter 54 fixes the light for measuring the free end displacement of the cantilever free end 14 a (stylus 34) and the cantilever holder 16. Separated into light for measuring end displacement. A part of the light for measuring the free end displacement is reflected by the reference mirror 22 to become reference light, and the remaining transmitted light is transmitted by the λ / 4 plate 58 and then reflected by the free end measurement portion 14c on the back surface of the cantilever 14. The light passes through the λ / 4 plate 58 again and is superimposed on the reference light.
At this time, the reference light and the reflected light are lights whose polarization planes are orthogonal to each other, and the phase difference between them is detected by the free-end phase detection unit 24 and appropriate signal processing is performed. As a result, since the Z displacement information of the stylus 34 can be obtained with the reference mirror 22 as a reference, the unevenness on the surface of the workpiece 40 can be grasped.

According to the shape measuring apparatus 10 according to the present embodiment, even if a movement error of the scanning stage 18 occurs during scanning of the cantilever 14, as long as the stylus 34 is in contact with the surface of the workpiece 40, the cantilever Since the movement error is absorbed by the bending of the cantilever 14 only by bending of the scanning stage 14, the movement error of the scanning stage 18 can be prevented from being superimposed on the measurement result of the workpiece 40.
In the present embodiment, the lens 60 converges the laser beam from the reference mirror 22 on the free end measurement portion 14c on the back surface of the cantilever 14 and enters the measurement light. Injected onto the free end measurement axis of the. As a result, in this embodiment, even if there is a concern about the influence of the tilt change of the back surface of the cantilever 14 due to the bending of the stylus 34, the measurement light from the free end measurement portion 14c on the back surface of the cantilever 14 is surely obtained. Since it is emitted from the lens 60 and can be observed by the free end displacement meter 24, the Z displacement of the stylus 34 can be accurately measured.

By the way, in this embodiment, in order to perform more stable and highly accurate measurement, it is also very important to pay attention to the following points.
According to the scanning probe microscope 10 according to the present embodiment, it is possible to realize highly accurate measurement that is not affected by the movement error of the scanning stage 18 as described above. This is a measurement object having a fine shape that can be measured within the deflection range of the cantilever 14, and when the surface of the workpiece 40 has a large undulation, the stylus 34 may move away from the surface of the workpiece 40 during scanning. Measurement cannot be performed.
Further, if the height of the back surface of the cantilever 14 is greatly shifted from the focal position of the lens 60 using the lens 60, an error amount due to the tilt of the back surface of the cantilever 14 cannot be removed. Further, depending on the work, the amount of deflection of the cantilever 14 becomes very large, and an excessive measuring force may be applied. As a result, the surface of the workpiece 40 may be damaged, or the stylus 34 may be worn, and the lateral resolution of the measurement may be reduced.

In this embodiment, in order to perform more stable and highly accurate measurement, it is very important to solve these problems, and in order to realize stable and highly accurate measurement even on a rough workpiece surface. Further, in order to suppress damage to the surface of the work 40 and reduce wear of the stylus 34, the amount of deflection of the cantilever 14 is controlled to be constant during measurement.
In this embodiment, in order to perform constant control of the deflection amount of the cantilever 14, the deflection amount information of the cantilever 14 is obtained as follows.

  A part of the light for measuring the free end displacement and the light for measuring the fixed end displacement separated by the beam splitter 54 is reflected by the reference mirror 22 to become reference light, and the remaining transmitted light is the λ / 4 plate. After passing through 58, the light is reflected by the free end measurement portion 14 c on the back surface of the cantilever 14 and the mirror 70 on the cantilever holder 16, and again passes through the λ / 4 plate 58 and overlaps with the reference light. At this time, the reference light and the reflected light are lights whose polarization planes are orthogonal to each other, and these phase differences are detected by the phase detectors 24 and 26 and subjected to appropriate signal processing. As a result, the Z displacement information of the free end measurement portion 14c on the back surface of the cantilever 14 and the cantilever holder 16 can be obtained based on the reference mirror 22. The change Δξ in deflection of the cantilever 14 can be obtained from the free end measurement portion 14 c on the back surface of the cantilever 14 and the Z displacement information of the cantilever holder 16.

  In this embodiment, by controlling the Z position of the cantilever holder 16 so that the deflection change Δξ obtained in this way is constant, the stylus 34 moves the workpiece 40 during scanning as shown in FIG. It is possible to reliably avoid the separation from the surface and perform a correct measurement.

Hereinafter, a method of obtaining the deflection change Δξ of the cantilever 14 from the moving end displacement information and the fixed end displacement information obtained during the scanning of the cantilever 14 will be described with reference to the schematic diagram of FIG.
At an arbitrary measurement start point on the workpiece 40, the distance of the back surface of the cantilever 14 with respect to the reference mirror 22 is l ₀ , and the distance of the cantilever holder 16 with respect to the reference mirror 22 is m ₀ . When the cantilever 14 is scanned, the distance l _{0 of} the back surface of the cantilever 14 with respect to the reference mirror 22 and the distance m ₀ of the cantilever holder 16 with respect to the reference mirror 22 are the distance l ₁ , respectively, due to the shape of the workpiece 40 and the vertical movement of the cantilever holder 16. Assume that the distance has changed to m ₁ .
When the deflection amount of the cantilever 14 at the measurement start point is set as ξ ₀ , the deflection change amount Δξ is obtained from the distances l ₁ and m ₁ obtained after scanning by the following equation.
Δξ = (l ₀ −m ₀ ) − (l ₁ −m ₁ ) = ξ ₀ −ξ ₁
That is, the change in the difference between the moving end displacement information and the fixed end displacement information represents the amount of change with respect to the deflection of the cantilever 14 at the measurement start point.

In the present embodiment, using the information of the change amount Δξ, the driving of the Z-direction drive mechanism 20 is controlled so as to keep the deflection amount of the cantilever 14 at the deflection amount setting value.
In other words, in this embodiment, when measuring the Z displacement of the stylus 34 with the reference mirror 22 as a reference in order to obtain unevenness information on the surface of the work 40, the deflection amount measurement value obtained as described above is the deflection. The surface of the workpiece 40 is scanned while moving the cantilever holder 16 up and down so that the amount setting value is obtained.
As a result, in the present embodiment, stable and highly accurate measurement can be performed on the surface of the workpiece 40 having undulations exceeding the range of deflection of the cantilever 14 without the stylus 34 separating from the surface of the workpiece 40.
In the present embodiment, since the free end measurement portion 14c on the back surface of the cantilever 14 is always located near the focal point of the lens 60, the measurement error due to the tilt of the cantilever 14 can be greatly reduced.
In the present embodiment, the measuring force determined according to the deflection amount of the cantilever 14 can be controlled to a predetermined constant value, and therefore the measuring force can be kept small. As a result, damage to the workpiece 40 can be avoided and wear of the stylus 34 can be suppressed as much as possible.
Accordingly, in the present embodiment, since the unevenness of the workpiece surface can be accurately grasped based on the free end displacement information from the free end phase detection unit 24, the Z displacement measurement of the stylus 34 based on the reference mirror 22 can be performed. Therefore, further stabilization and higher accuracy can be realized with certainty.

In the above-described configuration, an example in which the scanning stage 18 sends and moves the stylus 34 and the displacement gauges 24 and 26 in the X direction with respect to the workpiece 40 and the reference mirror 22 has been described. Without being limited thereto, it is also preferable to move the work 40 and the reference mirror 22 in the X direction with respect to the stylus 34 and the displacement meters 24 and 26.
Further, not only one axis in the X axis direction but also the same scanning measurement can be performed in the Y direction, and the uneven shape of the workpiece 40 in the two-dimensional region can be measured.

  In the above configuration, the example in which the reference mirror 22 and the λ / 4 plate 58 are provided as the optical elements of the light wave interference displacement meter has been described. However, the present invention is not limited to this, and the reference mirror 22 and Instead of the λ / 4 plate 58, a wire grid type polarizing plate may be used. If this is used, the polarization planes of the reflected light and the transmitted light are orthogonal to each other, and the functions of both the reference mirror 22 and the λ / 4 plate 58 of the present embodiment can be realized with one optical element. Simplification is achieved.

  In the above configuration, the example in which the displacement of the cantilever holder 16 is observed as the displacement of the cantilever fixed end 14b has been described. As long as the displacement of the cantilever fixed end 14b can be observed, the Z displacement of the cantilever fixed end 14b can be observed by observing the Z displacement of the lens holder 74 or the like, for example.

  In the above embodiment, an example in which an optical interference system is used as the displacement gauges 24 and 26 has been described. However, the present invention is not limited to this, and the displacement can be observed as long as the displacement can be observed. Other displacement meters, such as a capacitive displacement meter, can also be used.

Second Embodiment FIG. 4 shows a schematic configuration of a fine shape measuring apparatus according to two embodiments of the present invention. Parts corresponding to those in the first embodiment are denoted by reference numeral 100 and description thereof is omitted.
In the present embodiment, as the fixed end displacement meter 126, a capacitance displacement meter is used instead of the light wave interference displacement meter. This is provided on the upper part of the cantilever holder 116.
The reference mirror 122 of the present embodiment is coated with a metal foil film, and this is used as the reference electrode 180 of the capacitance displacement meter. The capacitive displacement meter 126 includes a detection electrode 182.
The fixed-end displacement meter 126 measures the change in capacitance between the reference electrode 180 and the detection electrode 182. Based on the change in capacitance, the fixed-end displacement information, that is, between the reference mirror 122 and the cantilever holder 116 is measured. The change of Z distance is grasped.
According to the fixed end displacement meter 126 of this embodiment, highly accurate fixed end displacement information can be obtained.

  In the free end displacement meter 124, the laser light from the light source 150 is collimated by the lens 152 and then passes through the beam splitter 156. A part of the light for measuring the free end displacement is reflected by the reference mirror 122 to become reference light, and the remaining transmitted light is transmitted by the λ / 4 plate 158 and then reflected by the free end measurement portion 114c on the back surface of the cantilever 114. Then, the light passes through the λ / 4 plate 158 again and is superimposed on the reference light. At this time, the phase difference between the reference light and the reflected light is detected by the free end phase detection unit 124 and subjected to appropriate signal processing, so that the free end displacement information, that is, the Z displacement of the stylus 134 based on the reference mirror 122 is obtained. Information can be obtained.

  According to the fixed end displacement meter 126 of the present embodiment, the deflection amount of the cantilever 114 is increased based on the fixed end displacement information obtained as described above and the free end displacement information obtained by the free end displacement meter 124. The accuracy can be obtained. In the present embodiment, based on the free end displacement information obtained by scanning the surface of the workpiece 140 while raising and lowering the cantilever holder 116 so that the deflection amount measurement value becomes the deflection amount setting value by the control unit 130. Since the shape of the surface of the workpiece 140 is grasped, the fine shape measurement can be performed more stably and accurately as in the case of the above embodiment.

  Further, in the present embodiment, a capacitance type displacement meter is provided on the upper portion of the cantilever holder 116 as the fixed end displacement meter 126, and a change in the distance between the reference mirror 122 and the cantilever holder 16 is measured. As a result, in this embodiment, since it is sufficient to provide one optical system for measuring displacement, the apparatus can be simplified as compared with an apparatus having two optical systems for measuring displacement. .

Third Embodiment FIG. 5 shows a schematic configuration of a fine shape measuring apparatus according to a third embodiment of the present invention. Portions corresponding to those of the second embodiment are indicated by reference numeral 100 and description thereof is omitted.
In the present embodiment, as the fixed end displacement meter 226, a ring-shaped detection electrode 282 is provided on the lens holder 274 to constitute a capacitance displacement meter.
In other words, in the present embodiment, the detection electrode 282 of the capacitive displacement meter has a ring shape, and the center axis of the ring detection electrode 282 matches the center line of the free end measurement axis of the free end displacement meter 224. As described above, the ring-shaped detection electrode 282 is disposed on the free end measurement axis of the free end displacement meter 224. Further, the λ / 4 plate 258 of the free end displacement meter 224 is disposed in the ring-shaped detection electrode 282 of the fixed end displacement meter 226.
As described above, according to the present embodiment, since the fixed end displacement meter 226 measures a change in the distance between the reference mirror 222 and the lens holder 274, highly accurate fixed end displacement information can be obtained.

  According to the fixed end displacement meter 226 of the present embodiment, the deflection amount of the cantilever 214 is highly accurate based on the fixed end displacement information obtained as described above and the free end displacement information obtained by the free end displacement meter 224. Can be requested. In the present embodiment, the control unit 230 is based on the free end displacement information obtained by scanning the surface of the work 240 while moving the cantilever holder 216 up and down so that the measured value of the deflection amount of the cantilever 214 becomes a set value. Since the shape of the surface of the work 240 is grasped, the fine shape measurement can be performed more stably and with high accuracy as in the above embodiment.

  Furthermore, in this embodiment, since it can be considered that the relative distance between the lens 260 and the back surface of the cantilever 214 is measured on the same axis, even when the posture of the cantilever holder 216 changes, The amount of deflection of the cantilever 214 can be accurately calculated. As a result, since the constant control of the deflection amount of the cantilever 214 can be accurately performed, a more stable and highly accurate fine shape measurement can be performed.

Fourth Embodiment FIG. 6 shows a schematic configuration of a fine shape measuring apparatus according to a fourth embodiment of the present invention. Parts corresponding to those in the third embodiment are denoted by reference numeral 100 and description thereof is omitted.
In this embodiment, the metal thin film 380 of the reference mirror 322 is used as a detection electrode, and the distance to the detection surface (reference electrode) 382 provided on the upper portion of the lens holder 374 is measured. According to the fixed end displacement meter 326 of the present embodiment, highly accurate fixed end displacement information can be obtained.

  According to the present embodiment, the deflection amount of the cantilever 314 can be obtained with high accuracy based on the fixed end displacement information obtained in this way and the free end displacement information obtained by the free end displacement meter 324. The control means 330 uses the free end displacement information obtained by scanning the surface of the work 340 while moving the cantilever holder 316 up and down so that the measured value of the deflection amount of the cantilever 314 obtained in this way becomes a set value. Based on this, the shape of the surface of the workpiece 340 is grasped, so that the fine shape measurement can be performed more stably and with high accuracy as in the above embodiment.

  Furthermore, since the capacitive displacement meter of the present embodiment is used in a state that is always fixed by the scanning, the cantilever 314 can be scanned while the capacitance displacement meter cable is fixed. . As a result, in this embodiment, adverse effects such as hysteresis due to cable movement of the capacitance displacement meter can be greatly reduced.

In each of the above embodiments, the example in which the interference length measurement unit is moved has been described. However, the present invention is not limited to this, and it is also preferable to fix the interference length measurement unit. Specific examples thereof will be described below.
Fifth Embodiment FIG. 7 shows a schematic configuration of a fine shape measuring apparatus according to a fifth embodiment of the present invention. Portions corresponding to those in the first embodiment are indicated by the reference numeral 400 and description thereof is omitted.
In the first embodiment, the interference length measurement unit including the displacement meter is moved, but in the present embodiment, the interference length measurement unit including the displacement meters 424, 426 and the like is fixed.
Further, the laser light from the light source 450 is spread to the same size as the workpiece 440. Of the laser light, part of the light that has passed through the light shielding plate 490 is reflected by the reference mirror 422 to become reference light, and the remaining transmitted light is reflected by the cantilever back surface 414c and the reflection mirror 470, respectively, and is superimposed on the reference light. Is incident on the phase detectors 464 and 472.
In the present embodiment, the displacement at the same place can always be observed by fixing the light shielding plate 490 to the scanning stage 418 and moving it together with the cantilever 414 and the reflection mirror 470.
In the present embodiment, the optical path of the reflected light also moves in accordance with the movement of the light shielding plate 490. However, by arranging the lenses 492 and 494, light always enters the predetermined positions of the phase detectors 464 and 472. It is the composition which does.
As described above, according to the present embodiment, the mass of the movable part can be reduced by fixing the interference length measuring unit including the displacement gauges 424, 426 and the like, so that the scanning stage 418 can be moved at high speed. . Thereby, in this embodiment, the measurement time can be further shortened.

It is explanatory drawing of schematic structure of the fine shape measuring apparatus concerning 1st embodiment of this invention. It is explanatory drawing of the subject which this invention tends to solve. It is explanatory drawing of an effect | action of the fine shape measuring apparatus concerning this embodiment. It is explanatory drawing of schematic structure of the fine shape measuring apparatus concerning 2nd embodiment of this invention. It is explanatory drawing of schematic structure of the fine shape measuring apparatus concerning 3rd embodiment of this invention. It is explanatory drawing of schematic structure of the fine shape measuring apparatus concerning 4th embodiment of this invention. It is explanatory drawing of schematic structure of the fine shape measuring apparatus concerning 5th embodiment of this invention.

Explanation of symbols

10, 110, 210, 310, 410 Scanning probe microscope (fine shape measuring device)
14, 114, 214, 314, 414 Cantilever 18, 118, 218, 318, 418 Scanning stage (scanning means)
20, 120, 220, 320, 420 Z-direction drive mechanism (drive means)
22, 122, 222, 322, 422 Reference mirror (reference member)
24, 124, 224, 324, 424 Moving end displacement meter 26, 126, 226, 326, 426 Fixed end displacement meter 28, 128, 228, 328, 428 Calculation means 30, 130, 230, 330, 430 Control means 32, 132,232,332,432 Analysis means 34,134,234,334,434 stylus

Claims (7)

A cantilever having a stylus at the free end for tracing the irregularities of the workpiece surface with the fixed end held, and having flexibility in the vertical direction;
Scanning means for relatively scanning the cantilever and the workpiece surface in the lateral direction;
Drive means for moving the cantilever fixed end up and down;
A reference member provided so that the relative position and posture with respect to the workpiece do not change even by the scanning;
A free end displacement meter that measures the relative displacement in the vertical direction between the reference member and the stylus and outputs free end displacement information;
A fixed end displacement meter that measures relative displacement in the vertical direction between the reference member and the cantilever fixed end, and outputs fixed end displacement information;
Based on the free end displacement information obtained by the free end displacement meter and the fixed end displacement information obtained by the fixed end displacement meter, calculation means for obtaining a vertical deflection amount of the cantilever;
Control means for controlling the operation of the driving means, and controlling the vertical position of the cantilever fixed end so that the amount of deflection determined by the calculating means becomes a predetermined value;
And grasping the shape of the workpiece surface based on the free end displacement information obtained by scanning the workpiece surface while moving the cantilever fixed end up and down so that the deflection amount of the cantilever becomes a predetermined value. A fine shape measuring device characterized by. In the fine shape measuring apparatus according to claim 1,
In the scanning means, the vertical free end displacement axis of the stylus and the free end measurement axis of the free end displacement meter always coincide with each other, and the vertical fixed end displacement axis and the fixed end displacement meter of the cantilever fixed end The workpiece and the reference member are scanned with respect to the cantilever and the displacement meter, or the cantilever and the displacement meter are scanned with respect to the workpiece and the reference member so that the fixed end measurement axis of Fine shape measuring device. In the fine shape measuring apparatus according to claim 1 or 2,
The free end displacement meter is a light wave interference displacement meter, and the reference member is a reference mirror of a light wave interference displacement meter,
The free end displacement meter includes a reference light which is a reflected light from a reference mirror obtained by allowing a part of coherent light to enter the reference mirror, and a free end which is transmitted through the reference mirror and located on the stylus on the back surface of the cantilever. A fine shape measuring apparatus characterized in that measurement light, which is reflected light obtained by being incident on a measurement site, is caused to interfere with a reference mirror and the moving end displacement information based on the interference is obtained. In the fine shape measuring apparatus according to claim 3,
The free end displacement meter includes a lens that is laterally scanned together with the cantilever in a state where the free end displacement meter is inserted into a parallel light beam having coherence from the reference mirror.
The lens converges and enters the parallel light beam from the reference mirror on the free end measurement portion on the back surface of the cantilever, and emits the measurement light, which is reflected light, onto the free end measurement axis of the free end displacement meter. A fine shape measuring device characterized by. In the fine shape measuring apparatus according to any one of claims 1 to 4,
The fixed-end displacement meter is a light wave interference displacement meter, and the reference member is a light wave interference displacement meter reference mirror,
The fixed-end displacement meter includes a reference light that is a reflected light from a reference mirror obtained by making a part of coherent light enter the reference mirror, and a reference light that passes through the reference mirror and substantially enters the cantilever fixed end. A fine shape measuring apparatus characterized in that the measurement light, which is the reflected light, is caused to interfere with a reference mirror to obtain the fixed end displacement information based on the interference. In the fine shape measuring apparatus according to any one of claims 1 to 5,
The fixed-end displacement meter is a capacitance displacement meter including a reference electrode and a detection electrode that are two electrodes facing each other in the vertical direction,
The reference electrode is provided on the reference member, and the detection electrode is substantially provided on the cantilever fixed end;
The fine shape measuring apparatus, wherein the fixed end displacement meter measures a change in capacitance between the reference electrode and the detection electrode and obtains fixed end displacement information based on the change in capacitance. In the fine shape measuring apparatus according to claim 6,
The detection electrode is a ring-shaped electrode,
Disposing the ring-shaped detection electrode on the free end measurement axis of the free end displacement meter so that the center axis of the ring detection electrode and the free end measurement axis of the free end displacement meter coincide with each other. Characteristic fine shape measuring device.

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