JPH05273120A - Polarization analyzer - Google Patents

Abstract

PURPOSE:To provide a polarization analyzer capable of measuring many kinds of physical properties on a sample and adaptable to various measurement uses. CONSTITUTION:A sample 2 to be measured is fixed on a sample fixing base 1 for measurement. If physical properties are changed in direction around the normal line on the sample surface 2a of the sample 2, the sample 2 is rotated by a sample base rotating device 4, and measurement is made at rotated positions to obtain the desired measurement result. An adjustment is made by a flap adjusting device 12 in advance before measurement is started so that the incidence angle to the sample surface 2a is made equal before and after the rotation of the rotating device 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ellipsometer for measuring physical properties such as a refractive index, an absorption coefficient and a film thickness of a sample, and particularly to increase the measurable physical properties. is there.

[0002]

2. Description of the Related Art There is an ellipsometer for measuring physical properties such as a refractive index, an absorption coefficient and a film thickness of a sample according to an ellipsometry method. For example, it is described in Japanese Utility Model Laid-Open No. 25838/1990.

The polarization analyzer described in this publication measures the film thickness of the sample surface by injecting polarized light into the sample surface and detecting the polarization state of the reflected light. It is characterized in that it is provided with a sample table moving means for moving the table parallel to the mounting surface.

FIG. 7 is a schematic block diagram of the polarization analyzer described in this publication. In FIG. 7, the laser light emitted from the He—Ne laser light source 21 passes through a chopper 22 that removes the influence of extraneous light, and then sequentially passes through a rotation-adjustable polarizer 23 and a λ / 4 plate 24. It is converted into a predetermined polarized light and is incident on the sample 28. Sample 2
Reflected light having a polarization state according to the refractive index and film thickness of the surface of 8 passes through a rotatable analyzer 25 to be made into component light having an oscillating surface in a predetermined direction, and then the detector 2
It is photoelectrically converted by 6 and applied to an arithmetic unit (not shown) that calculates the film thickness of the sample by arithmetic operation. The arithmetic device is also provided with position information of the polarizer 23 and the analyzer 25. The arithmetic device adjusts the positions of the polarizer 23 and the analyzer 25, and based on the received light amount information from the detector 26, the sample 28 The film thickness of is measured.

Here, the sample 28 is placed on the sample table 27. The sample table 27 is supported by the arm 29 a of the stage driving device 29, and the stage driving device 29 moves the arm 29 a to move the sample table 27 in a plane parallel to the mounting surface of the sample 28, that is, the sample table 27. 27 is shown in FIG.
It can be moved to the left and right and back and forth. That is, the film thickness can be quickly measured at a plurality of points on the sample.

Although the ellipsometer described in the above publication is intended for film thickness measurement, it can be applied to the case of measuring optical characteristics such as refractive index and absorption coefficient at a plurality of points of a sample.

[0007]

By the way, it goes without saying that a measuring device for measuring the physical properties of a sample is preferably the more the physical properties that can be measured by the measuring device alone.
From this point of view, the conventional ellipsometer can be said to be good because it can measure a plurality of physical properties such as the refractive index, the absorption coefficient, and the film thickness of the sample, but it is still limited and still has a limit. Is insufficient.

That is, the conventional ellipsometer is intended for a sample having optical isotropy as described in various documents, and the sample is placed parallel to the mounting surface of the sample table. Even a movable ellipsometer requires that the sample has optical isotropy. That is, the conventional ellipsometer has not been used for measurement of a sample having optical anisotropy. This is because when measuring physical properties such as optical properties of a sample having optical anisotropy, the value obtained depending on the angle at which the polarized light is incident with the normal to the sample surface as the center. This is because they are different.

In practice, it may be necessary to measure the physical properties of a sample having optical anisotropy. In this case, conventionally, the measurement was performed by an optical measuring device different from the polarization analyzer. For example, a measurement method using a so-called V block has been adopted for measuring the refractive index of a sample having optical anisotropy (for example, JP-A-61-1).
69848). However, this method cannot measure other physical properties. Further, there are problems that the measurement by the ellipsometer does not pose a problem such as destructive inspection, the need for a large bulk sample, and the inability to use the inspected one.

Further, even when a sample having optical isotropy is used as a measurement target, the physical properties measurable by the conventional ellipsometer are limited as described above. For example, the optical property having optical isotropy is obtained. It is not possible to confirm whether the sample cut parallel to the crystal plane is truly parallel.

The present invention has been made in consideration of the above points, and aims to provide an ellipsometer capable of increasing the number of types of measurable physical properties of a sample as compared with conventional ones and adapting to a variety of measurement applications. It is what

[0012]

In order to solve such a problem, in the present invention, polarized light is incident on the surface of the sample, and the polarization analyzer for measuring the physical property of the sample based on the polarization state of the reflected light. In the above, at least one of the sample fixing base for fixing the sample and the optical system for injecting the polarized light on the sample surface and optically processing the reflected light from the sample surface is equipped with a rotation mechanism having the normal line of the sample surface as an axis. It is characterized by

Here, the sample fixing table or the optical system having the rotating mechanism is provided with a tilt adjusting device capable of adjusting the incident angle with respect to the sample before and after the rotation even when the rotating mechanism rotates. Preferably.

[0014]

In the ellipsometer of the present invention, the sample for measurement is fixed on the sample fixing base for measurement. Here, the physical properties that the sample changes its physical properties depending on the azimuth around the normal of the sample surface, or the physical properties that give results by injecting light from multiple azimuths around the normal of the sample surface If it has, a desired measurement result can be obtained by rotating the sample around the normal line of the measurement surface of the sample by the rotation mechanism and measuring at each rotation position.

For example, the angle dependence of the refractive index and absorption coefficient of the surface of a material having optical anisotropy, the presence or absence of optical anisotropy of an unknown material, and the parallel to the crystal plane having optical anisotropy It is possible to measure whether or not the measurement surface is cut out.

Here, if the incident angle to the sample changes before and after the rotation by the rotating mechanism, the desired measurement cannot be performed accurately. Therefore, a tilt adjustment device is provided on the sample fixing table or the optical system equipped with the rotation mechanism, and by the adjustment by the tilt adjustment device,
It is preferable that the incident angle with respect to the sample surface before and after the rotation by the rotating mechanism be the same.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. Here, FIG. 1 is a schematic configuration diagram of a polarization analyzer according to this embodiment.

In FIG. 1, the surface 2a of the sample 2 has H
The emitted light emitted from the e-Ne laser light source 5 is sequentially irradiated through a polarizer 6, a collimator lens 7, and a quarter-wave plate 8 which are rotatable around the optical axis. That is, the light emitted from the He—Ne laser light source 5 is converted into polarized light having a predetermined azimuth angle by the polarizer 6, and then converted into parallel light by the collimator lens 7, and the P component and the P component and After the phase difference of ¼ wavelength is given to the S component, the surface of the sample 2 is irradiated with the phase difference. The light reflected by the surface 2a of the sample 2 has a polarization state in which the physical properties of the sample 2 are reflected, and is incident on the semiconductor photodetector 11 via the analyzer 9 and the filter 10 which are rotatable around the optical axis in order. To be done. That is, a component of a predetermined azimuth angle of the reflected light passes through the analyzer 9, the light other than the light from the laser light source 5 is removed by the filter 10, and then the semiconductor photodetector 11 performs photoelectric conversion.

Then, an arithmetic unit (not shown) uses a polarizer 6 according to the received light amount information from the semiconductor photodetector 11 or the like.
The azimuth angle (rotational position) of the analyzer 9 is controlled, and a value representing the desired physical property of the sample 2 is calculated based on the received light amount information and the rotational position information.

The sample 2 measured by the above measuring optical system is fixed to the sample fixing base 1. As will be described later, the sample fixing base 1 according to this embodiment can rotate about a normal line passing through the irradiation position of the measurement surface 2a of the sample 2 as an axis, and in this respect, it is largely different from the conventional polarization analyzer. Different.

FIG. 1 schematically shows this sample fixing base 1. The sample holder 1 is a sample table 3 on which the sample 2 is placed.
And a tilt adjusting device 12 for adjusting the inclination of the mounting surface 3a of the sample table 3 and a sample table rotating device 4 for rotatably controlling the sample table 3. In this embodiment, the sample table 3 and the tilt adjusting device 12 are integrally formed.
Further, the sample table rotating device 4 includes a fixed table 4a and a rotary knob 4a.
and b.

FIG. 2 is a perspective view of the sample fixing base 1.
The fixed table 4a is provided with a fixed rotation amount scale of, for example, 5 degrees in a range of 25 degrees, and the rotary knob 4b provided on the upper portion of the fixed table 4a is rotated by, for example, 30 degrees. Quantity scales are provided in the range of 360 degrees, and the rotary knob 4b can be accurately rotated by an arbitrary angle within the range of 360 degrees by combining these scales.

The tilt adjusting device 12 comprises first and second adjusting mechanisms 12a and 12b, and the first adjusting mechanism 12a.
The inclination angle adjusting direction of the mounting surface 3a by the above and the inclination angle adjusting direction of the mounting surface 3a by the second adjusting mechanism 12b are in a relation orthogonal to each other. Therefore, the mounting surface 3a can be tilted in any direction by adjusting the first and second adjusting mechanisms 12a and 12b.

More specifically, the first adjusting mechanism 12a includes a fixed portion 12a1 having a convex groove portion fixedly provided on the upper portion of the rotary knob 4b and a concave groove portion movably provided on the upper portion. Movable part 12a2 and adjusting screw 1
2a3. Fixed part 12a1 and movable part 12a2
Are in contact with each other, including both dovetail grooves, through a sliding surface forming a side surface of a cylinder, and the inside of the sliding surface is opened. In the opening (not shown), the adjusting screw 12a3 provided on the fixed portion 12a1 and the engaging screw provided on the movable portion 12a2 are screwed together, and the movable portion 12a2 swings by the rotation of the adjusting screw 12a3. Therefore, the mounting surface 3a can be inclined in a predetermined direction. The side surface of the first adjusting mechanism 12a is graduated so that the measurer can recognize the amount of inclination of the mounting surface 3a.

The second adjusting mechanism 12b has the same structure as that of the first adjusting mechanism 12a, and therefore its explanation is omitted.

The ellipsometer of the embodiment having the above-described schematic structure can measure the physical properties of a sample as in the conventional case. That is, the refractive index, absorption coefficient, and film thickness of a sample having optical isotropy can be measured.

In addition to this, in the ellipsometer of the embodiment, since the measurement surface 2a of the sample 2 can be rotated, new physical properties can be measured. For example, whether or not the substance has optical anisotropy, the angular dependence of the refractive index and the absorption coefficient of the sample having optical anisotropy (change of the characteristic value due to the angle around the normal to the sample surface) It is possible to measure the parallelism of the measurement surface 2a with respect to the crystal plane.

As described above, when the physical properties are measured by rotating the sample 2, the tilt adjusting device 12 is used in advance to set the sample stage rotating device to the normal line passing through the irradiation position of the surface (measurement surface) 2a of the sample 2. It is necessary to match the four rotation axes. This is because when the rotation axis of the sample stage rotating device 4 does not coincide with the normal line, the incident angle changes with rotation, and this change in the incident angle adversely affects the measurement result.

After carrying out such tilt adjustment, sample 2
Is rotated by a predetermined amount and the measurement is performed in that state, and the measurement at each rotational position is repeated to obtain the measurement result of the desired physical property.

In practice, the polarization analyzer of the embodiment is often used to obtain the refractive index at each rotational position. When the measurement surface 2a of the sample 2 has optical anisotropy, a rotational angle-refractive index characteristic curve (angle dependence of refractive index) can be obtained from the value of this refractive index. If each rotation position is set finely, a good characteristic curve of the rotation angle-refractive index can be obtained. However, it is preferable that the characteristic curves are different by about 5 degrees in consideration of the measurement time and the like. In such a case, a continuous smooth curve cannot be obtained as the rotation angle-refractive index characteristic curve. Therefore, when the relationship between the rotation angle and the refractive index is obtained by rotating each angle to some degree (for example, 5 degrees), the characteristic curve in which the rotation angle and the refractive index are continuous is obtained by processing the measurement result.

The index ellipsoid equation for an anisotropic crystal is given by the following equation (1), as is well known.

[0032]

[Equation 1] In the equation (1), nmax is the maximum value of the refractive index of the anisotropic crystal, nmin is the minimum value of the refractive index of the anisotropic crystal, and θ is the method from the position of taking the minimum value nmin of the refractive index. The angle around the line axis and the refractive index at that position is n (θ).

Therefore, by applying the equation (1) as a theoretical formula of the curve, the actual measured refractive index of the sample 2 obtained at each rotation angle is optimized by the method of least squares. Can be measured at certain rotation angles, a continuous rotation angle-refractive index characteristic curve can be obtained.

Even if a sample having optical anisotropy is measured by an ellipsometer equipped with a sample fixing table which does not allow rotation about the normal line of the measurement surface 2a of the sample 2 as in the conventional case. , Only obtaining the refractive index from one direction, to obtain the refractive index from all directions, there is no choice but to obtain by rotating the sample one by one. Therefore, according to the ellipsometer of this embodiment, The accuracy and reliability are much improved compared to the conventional one.

As described above, it has been described that the ellipsometer of the embodiment can obtain the rotation angle-refractive index characteristic curve (angle dependence of the refractive index) of the sample 2 having optical anisotropy. Now, it will be explained with an example that other physical properties as well as the angle dependency of the refractive index can be measured from the relationship between the rotation angle and the measured refractive index.

FIG. 3 shows rutile (TiO) which is a uniaxial crystal.
₂ ) The basic structure of a single crystal is shown in the abc axis. The rutile single crystal has optical isotropy in the (001) plane and optical anisotropy in the (100) plane and the (010) plane.

FIG. 4 shows the result of measuring the refractive index of this rutile single crystal. In FIG. 4, a straight line A is obtained by cutting and polishing a rutile single crystal parallel to the (001) plane having optical isotropy and using the surface as a measurement surface 2a, which is rotated by 5 degrees by a rotating mechanism 4. It is obtained from the measured refractive index. Further, the sinusoidal curve B is obtained from the measured refractive index obtained by cutting and polishing a rutile single crystal parallel to the (100) plane and using the surface as a measurement surface 2a and rotating the rotation mechanism 4 by 5 degrees each. It is a thing. In FIG. 4, ×
The marks are plots of the measured values of the refractive index at each rotation angle θ, and the rotation angle-refractive index line A and curve B were determined from these values.

Although the (001) plane of the rutile single crystal has optical isotropy as described above, the measurement result by the ellipsometer of this example (straight line A in FIG. 4) shows that the surface of the rutile single crystal is The refractive index was a constant value of 2.540 within the range of measurement error regardless of the rotation angle, and it was confirmed that the surface 2a of the sample 2 used in this experiment was correctly parallel to the (001) plane.

As described above, when the ellipsometer of this embodiment is used, not only the (001) plane of the rutile single crystal but also the sample surface 2a cut and polished in parallel to the crystal plane having optical isotropy. It is possible to confirm whether or not is cut in parallel and polished.

In contrast, rutile single crystal (100)
The surface parallel to the plane has optical anisotropy as described above,
As shown by the curve B in FIG. 4, the refractive index periodically fluctuates according to the rotation angle, and two points (θ = 87 degrees, 267 degrees) differing by 180 degrees while the sample 2 rotates 360 degrees around the normal line. ), The refractive index has a maximum value nmax (3.178), and two points differ by 180 degrees (θ = 177 degrees, 357 degrees).
Degree), the refractive index takes the minimum value nmin (2.443).

Here, if the measurement surface 2a of the sample 2 is (10
If not parallel to the (0) plane, the two maximum values nmax and the two minimum values nmin do not match. According to the measurement result of this time shown in the curve B of FIG. 4, the maximum value n of the two refractive indexes is n.
Since the max and the minimum value nmin of the two refractive indices match within the range of the measurement error, the surface 2a of the sample 2 of this rutile single crystal must be correctly parallel to the (100) plane. Was confirmed.

As described above, by using the ellipsometer of the embodiment, it is possible to confirm whether the sample cut parallel to the crystal plane having optical anisotropy is cut true parallel. ..

Further, as is clear from the comparison with the straight line A and the curved line B in FIG. 4, it is unknown whether the ellipsometer of the embodiment has optical isotropy or optical anisotropy. It is possible to determine which property each sample has.

FIG. 5 shows titanium phosphate, which is a biaxial crystal.
FIG. 6 is a schematic view of a potassium (KTiPO ₄ , hereinafter referred to as KTP) single crystal shown in the abc axis.
Is a plane parallel to the (100) plane of this KTP single crystal and (1
The results of measuring the refractive index with respect to the plane parallel to the (00) plane are shown. Curve A in FIG. 6 shows KTP single crystal (10
The surface is cut and polished parallel to the (0) plane, and the surface is used as the measurement plane. The sinusoidal curve B is a (00) KTP single crystal.
1) The surface was cut and polished parallel to the surface, and the surface was used as the measurement surface. In FIG. 6 as well, the mark “X” plots the measured values of the refractive index at each rotation angle, and the characteristic curve A or B of the rotation angle-refractive index was obtained from these values.

Since both the surface parallel to the (100) plane and the surface parallel to the (001) plane of the KTP single crystal have optical anisotropy, the refractive index as shown by curves A and B in FIG. Fluctuated periodically depending on the rotation angle.

The surface 2a parallel to the (100) plane of the KTP single crystal has the maximum value of the refractive index at two points (θ = 30 degrees, 210 degrees) which differ by 180 degrees while the sample stage 1 rotates through 360 degrees. nmax (1.873) was taken, and the minimum value nmin (1.749) of the refractive index was taken at two points (θ = 120 °, 300 °) which differed by 180 °. In addition, the surface of the KTP single crystal parallel to the (001) plane has 360
While rotating by one degree, two points that differ by 180 degrees (θ = 115
295 degrees), the maximum value of the refractive index nmax (1.7
51), and two points that differ by 180 degrees (θ = 25 degrees,
The minimum value of the refractive index nmin (1.73
I took 3).

Also in these cases, it is assumed that the measurement surface 2a of the sample 2 made of KTP single crystal is (100) plane or (0) plane.
01) If not parallel to each of the two planes, two maximum values nma
x or the two minimum values nmin do not match. Therefore, in the sample 2 which obtained the measurement result shown in FIG. 6, the two maximum values nmax and the two minimum values nmin coincide with each other within the range of the measurement error, so that the surface 2a is (100) plane or It is cut out in parallel to the (001) plane.

As described above, by using the ellipsometer of this embodiment, it is possible to confirm whether or not the sample 2 was cut out in parallel with the crystal plane correctly for the KTP single crystal. Moreover, even when it is unknown which of the two crystal planes having optical anisotropy is cut out in parallel,
This can be determined from the rotation angle-refractive index characteristic curve obtained by the measurement, as is apparent from the comparison from the curves A and B in FIG.

Although the physical properties that can be measured by the ellipsometer of the embodiment have been described above by using the measurement results of the experiment, the following physical properties can be further measured.

For example, an LPE is formed on an optically biaxial crystal substrate.
When a two-dimensional waveguide is constructed using the method, the required refractive index difference between the substrate and the epitaxial film must be evaluated, but the refractive index differs depending on the orientation measured in the same plane. , These are generally difficult to evaluate. However, by using the ellipsometer of the example, the curves of the angle dependence of the respective refractive indices of the substrate and the epitaxially grown thin film are obtained, and by comparing them, the relative refractive index difference can be estimated. ..

According to the ellipsometer of the above-mentioned embodiment,
Since the sample mounting base on which the sample is placed has a rotation mechanism that uses the normal line of the sample surface as an axis, it is possible to rotate the sample around the normal line of the sample surface for measurement, and use a conventional ellipsometer. In addition to the measured physical properties of the sample, various physical properties of the sample can be measured. As described above, the physical properties that can be measured only by the ellipsometer of this embodiment are the angle dependence of the refractive index of the measurement surface 2a of the sample 2 and the parallelism of the measurement surface 2a of the sample 2 with the crystal plane. Examples include confirmation, identification of the crystal plane of the measurement surface 2a of the sample 2, and confirmation of whether the measurement surface 2a of the sample 2 has optical isotropy or anisotropy. The angle dependence of the absorption coefficient on the measurement surface 2a of the sample 2 is also a physical property that can be measured only by the ellipsometer of this example.

Further, according to the ellipsometer of the above embodiment, since the tilt adjusting device 12 is provided, the measurement surface 2 of the sample 2 is
It is possible to adjust a so that it is perpendicular to the rotation axis of the sample table, and as a result, various physical properties described above can be measured correctly. Incidentally, in the case where the tilt adjusting device 12 is not provided, in order to correctly measure the above-mentioned various physical properties, the non-measurement surface side of the sample 2 is processed so that the measurement surface 2a of the sample 2 has the rotation axis of the sample table 1. Must be perpendicular to, which makes the measurement pre-processing very complicated.

Here, as described above, when the fitting curve (regression straight line or regression curve) is obtained by statistically processing the measured values of the angle dependence of various optical characteristics, the measurement result (whether it is the measurement of the refractive index or not) is obtained. For example, the accuracy of the maximum refractive index and the minimum refractive index can be improved. That is, not only the information about the angle for which the measurement value has not been obtained can be obtained, but even if the measurement value is obtained, the information in which the error introduced during the measurement is removed can be obtained.

In the above embodiment, the sample table on which the sample is placed is rotatable about the normal line of the measurement surface of the sample. However, the sample table is not rotatable and the optical system of the sample is changed. It may be rotatable about the normal line of the measuring surface as an axis, and the same effect as that of the above embodiment can be obtained.

In the above embodiment, the sample is only rotated. However, the sample table 3 is moved below the sample table 3 in parallel with the mounting surface (sample surface). A moving device may be provided so that the sample 2 can be moved in parallel. In this case, it becomes possible to quickly measure the physical properties (including the properties accompanied by the rotation operation) over the entire surface of the sample.

Further, in the above description of the embodiment, it was not clearly explained whether the arithmetic unit in the polarization analyzer (not shown) determines the rotation angle-refractive index characteristic curve or the like, but the rotation angle information from the rotation mechanism 4 is used. To the arithmetic unit,
Even if this arithmetic unit automatically performs the process of obtaining the characteristic curve of the rotation angle-refractive index, the process of determining whether or not the obtained curve or straight line information has optical anisotropy, etc. good.

Further, in the above embodiment, the sample holder is manually rotated by the measurer, but it may be automatically rotated by a command from an arithmetic unit (for example, a computer).

Furthermore, in the above embodiment, the sample 2 is placed and fixed on the sample table 3. However, the sample 2 may be fixed on the sample table by holding a non-measurement point by a supporting member or the like. However, if you do like this,
The sample mounting surface of the sample table 3 is not limited to the surface perpendicular to the vertical direction.

[0059]

As described above, according to the present invention, at least one of the sample fixing base for fixing the sample or the optical system for injecting the polarized light on the sample surface and optically processing the reflected light therefrom, Since it has a rotation mechanism that uses the normal line of the sample surface as an axis, when using a conventional ellipsometer, it can be measured only by physical properties that cannot be measured or by complicated operations such as repositioning the sample. It is possible to realize a versatile ellipsometer capable of easily measuring various physical properties.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an ellipsometer of an example.

FIG. 2 is a perspective view of the sample fixing base of FIG.

FIG. 3 is a structural diagram of a rutile single crystal.

FIG. 4 is an explanatory diagram showing the results of measuring the refractive index of rutile single crystal using the ellipsometer of the example.

FIG. 5 is a schematic view of a KTP single crystal.

FIG. 6 is an explanatory diagram showing the results of measuring the refractive index of a KTP single crystal using the ellipsometer of the example.

FIG. 7 is a schematic diagram of a conventional ellipsometer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sample fixing stand, 2 ... Sample, 3 ... Sample stand, 4 ... Sample stand rotating device, 12 ... Strain adjusting device.

Claims (2)

[Claims] 1. A polarization analyzer for injecting polarized light into a sample surface and measuring the physical properties of the sample based on the polarization state of the reflected light, comprising a sample fixing table for fixing the sample, or the sample. At least one of the optical systems for making polarized light incident on the surface and optically processing the reflected light from the surface is provided with a rotation mechanism having a normal line of the sample surface as an axis. 2. The sample fixing base provided with the rotating mechanism or the optical system can be adjusted so that the incident angle with respect to the sample before and after the rotation is the same even when the sample is rotated by the rotating mechanism. The ellipsometer according to claim 1, further comprising an adjusting device.