CN113048894B - Device and method for detecting change of reflected light and film thickness measuring device - Google Patents
Device and method for detecting change of reflected light and film thickness measuring device Download PDFInfo
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- CN113048894B CN113048894B CN202110240243.2A CN202110240243A CN113048894B CN 113048894 B CN113048894 B CN 113048894B CN 202110240243 A CN202110240243 A CN 202110240243A CN 113048894 B CN113048894 B CN 113048894B
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- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
- G01B11/0625—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection
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- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G01B11/0641—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of polarization
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
- G01B11/0675—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating using interferometry
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- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/8422—Investigating thin films, e.g. matrix isolation method
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Abstract
The invention provides a device and a method for detecting the change of reflected light.A first pupil splitter is used for splitting the field intensity of an incident beam so that the incident beam forms a first field intensity distribution on the first surface of the first pupil splitter; the incident light beam with the first field intensity distribution is collimated and converged to be obliquely incident to the surface of the object to form a reflected light beam with a second field intensity distribution; receiving the reflected beam having the second field strength distribution and collimating to form a reflected beam having a third field strength distribution; performing field intensity division on the reflected light beam with the third field intensity distribution by using the position and the shape of the second pupil divider, so that the reflected light beam with the third field intensity distribution forms a fourth field intensity distribution on the first surface of the second pupil divider, and the first pupil divider and the second pupil divider have the same aperture function distribution; and acquiring a reflected light beam with fourth field intensity distribution, and analyzing the reflected light beam change information with the fourth field intensity distribution in a time interval, so that the signal change formed by the light intensity change and the imaging position deviation after analysis is enhanced, and the signal-to-noise ratio of the detector is improved.
Description
Technical Field
The invention belongs to an acousto-optic measuring system, which is mainly used for detecting the measurement of a metal film and a dielectric film, and particularly relates to a device and a method for detecting the change of reflected light and a film thickness measuring device.
Background
The principle of acousto-optic measurement in the prior art is as follows: short pulse laser irradiates the surface of the film sample, the film sample absorbs photons to generate thermoelastic deformation, and a deformation region is formed on the surface; the thermoelastic deformation generates sound waves to be transmitted on the surface and inside of the solid; longitudinal sound wave is transmitted to an interface (the interface of the substrate or the film and the film) to generate a first echo signal; the first echo signal reaches the upper surface, so that the deformation morphology is further changed; the echo signal rebounds after touching the upper surface, and generates a second echo signal after rebounding and touching the interface; the second echo signal reaches the upper surface, which changes the bump topography again, as shown in fig. 1, although the echo signal may also include more than three times. The change of the reflectivity of the incident beam caused by the change of the topography is obtained through the optical detector, so that the time interval of the reflectivity change can be obtained twice, and the thickness value of the film sample can be calculated.
In a specific measurement apparatus, as shown in fig. 2, a pump laser 1 is incident on the surface of a sample 2 to generate a deformation region 4, and an incident probe light 5a is made to impinge on the deformation region 4, because the shape of the deformation region on the surface of a film layer changes during echo return, and further deformation of the deformation region generated when an echo signal arrives may affect a reflected probe light 5b, which may be amplitude or phase in cooperation with the use of an optical element at a receiving end, generally, a detection module 6 obtains a change in light reflection amplitude caused by the shape change, so as to obtain a time interval of the change in the amplitude of the optical signal, and obtains a film thickness value through a film thickness calculation formula, as shown in schematic diagrams of fig. 2 and fig. 3, and thus, detecting the change in the reflected probe light 5b is particularly important for improving the accuracy of the photoacoustic detection apparatus.
As shown in fig. 4, in order to analyze the reflected detection light, the detection light 5b reflected by the deformation region 4 will be reflected by the first reflector 6c to form a circular spot of half size (the position of the reflector 6c is particularly important, and it will screen the field of view of the reflected light spot), and this portion will continue to be reflected by the second reflector 6d to the second detector 6a, while the circular spot of the other half size which is not reflected by the first reflector 6c will directly enter the first detector 6 b. The first reflector 6c is adjusted to the target position by the motor, and the light received by the detectors 6a and 6b has a certain light intensity ratio when no excitation deformation exists, such as 1:1, but, when deformation 4 takes place to arouse deformation and produces echo oscillation, reflection detecting light 5b can take place the little angular variation of time dependence, at this moment because first speculum 6c is no longer half the relation to the segmentation effect of light spot visual field, because this kind of little angular variation can lead to the light intensity reading of detector 6a and 6b at this moment to change, can simulate the influence of calculating reflection detecting light 5b angle and both light intensity readings change through many times of experiments, and then can calculate the relation between the change of reflection detecting light 5b angle and the change of light intensity, through record many times echo signal time difference alright calculate the membrane thickness value.
However, the above-described technical solutions have the following problems: the first aspect has the problems that the position adjustment precision of the first reflector 6c of the applied optical system is extremely high, the stability of the optical system is also extremely high, the optical element bears the beam splitting effect, the requirements on the collimation and the stability of the optical path are high, and the assembly of the optical path is difficult; the second aspect is that the complexity of the optical path is reflected, the first reflector 6c and the second reflector 6d need to be assembled respectively, and in order to meet the requirement that the incident light within a certain angle can be effectively reflected and refracted, the parallel collimation and the field interleaving between the two also need to be accurately adjusted, and at the same time, 2 detectors are needed at the end of the detection emergent light, and the cost is increased due to the increase of the use of optical elements; the third party is present in detection precision, and due to the fact that light splitting is adopted for a light path, transmitted reflected light is further lost, and the change rate of light spot energy decomposition caused by incident angle deviation of reflected detection light due to a deformation region is more difficult to detect, so that the detection signal-to-noise ratio is low and is about one millionth, and the requirement on the waist divergence angle of a detection light beam is extremely high.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a device and a method for detecting the peak value change of reflected light, wherein pupil dividers with the same aperture function are arranged on an incident light path and a reflected light path of the detected light, and the pupil dividers are used for disturbing and dividing an incident light beam and a reflected light beam, so that the signal change formed by the light intensity change and the imaging position deviation after analysis is enhanced, the signal-to-noise ratio of a detector is improved, the structure is simple, the engineering realization is easy, the number of detectors is reduced, and the cost is reduced.
In order to solve the above technical problem, the present invention firstly proposes an apparatus for detecting a change in reflected light, the apparatus comprising:
at least one detection light source for generating an incident light beam;
the first pupil splitter is arranged behind the detection light source optical path and used for splitting the field intensity of the incident light beam so that the incident light beam forms a first field intensity distribution on a first surface of the first pupil splitter;
the first lens group is arranged behind the optical path of the first pupil splitter and is used for collimating and converging the incident beam with the first field intensity distribution to obliquely enter the surface of the object to be measured so as to form a reflected beam with a second field intensity distribution;
the second lens group is arranged on the reflection light path and used for receiving the reflected light beam with the second field intensity distribution in the field range and collimating the reflected light beam to form a reflected light beam with a third field intensity distribution;
the second pupil divider is arranged behind a light path of the second lens group and used for receiving the reflected light beam with the third field intensity distribution to carry out field intensity division, so that the reflected light beam with the third field intensity distribution forms a fourth field intensity distribution on the first surface of the second pupil divider, and the first pupil divider and the second pupil divider have the same aperture function;
and the detector is used for acquiring the reflected light beam with the fourth field intensity distribution and analyzing the change information of the reflected light beam with the fourth field intensity distribution in a time interval.
As a further improvement of the invention, the first lens group and the second lens group form an optical path collimation system, the first pupil splitter is arranged at the entrance pupil position of the optical path collimation system, and the second lens group is arranged at the exit pupil position of the optical path collimation system.
As a further improvement of the present invention, the first pupil splitter is provided with a plurality of first-type light-passing structures and a plurality of second-type light-passing structures, the first-type light-passing structures and the second-type light-passing structures have a difference in light flux, so that the incident light beam is perturbedly split by the first-type light-passing structures and the second-type light-passing structures into the incident light beam having the first field intensity distribution.
As a further improvement of the present invention, the second pupil splitter is provided with a plurality of light-passing structures of the third type and a plurality of light-passing structures of the fourth type, which have a difference in luminous flux, so that the reflected light beam having the third field intensity distribution is further perturbedly split into said reflected light beam having the fourth field intensity distribution.
As a further improvement of the present invention, the first-type light-transmitting structures and the third-type light-transmitting structures correspond to each other one by one, and the shapes of the first-type light-transmitting structures and the third-type light-transmitting structures which correspond to each other are the same.
As a further improvement of the invention, the field of view adjustment of the first lens group is realized by arranging the composition structure of the first lens group, so that the image of the first pupil divider clearly irradiates on the object to be measured; the field of view adjustment of the second lens group is realized by arranging the composition structure of the second lens group, so that the reflected light beam with the second field intensity distribution is collimated and then enters the second pupil divider.
As a further development of the invention, the first pupil splitter (7) and the second pupil splitter (8) are axisymmetric with respect to the incident light path and the reflected light path.
As a further improvement of the invention, the light-passing patterns corresponding to the plurality of first type light-passing structures are different.
In order to solve the above technical problem, the present invention further provides a method for detecting a change in reflected light, the method comprising:
the method comprises the steps that a first pupil divider is used for dividing the incident light beam into field intensity, so that the incident light beam forms a first field intensity distribution on a first surface of the first pupil divider;
the incident light beam with the first field intensity distribution is collimated and converged to be obliquely incident to the surface of the to-be-measured body so as to form a reflected light beam with a second field intensity distribution;
receiving the reflected beam having the second field strength distribution and collimating to form a reflected beam having a third field strength distribution;
receiving the reflected light beam with the third field intensity distribution by using a second pupil divider for field intensity division, so that the reflected light beam with the third field intensity distribution forms a fourth field intensity distribution on the first surface of the second pupil divider, wherein the first pupil divider and the second pupil divider have the same aperture function;
and acquiring a reflected light beam with a fourth field intensity distribution, and analyzing the reflected light beam change information with the fourth field intensity distribution in a time interval.
In order to solve the above technical problem, the present invention further provides a film thickness measuring apparatus, including:
the pump light source bursts a plurality of excitation sources from the upper surface to the lower bottom surface of the film to be detected at one time point so as to enable the upper surface of the film to be detected to generate at least one deformation area;
providing a device for detecting the change of the reflected light beam, and acquiring the change information of the signal intensity peak value of the polarized reflected light beam corresponding to the deformation area;
and the calculating unit is used for calculating the thickness of the film to be measured according to the time interval corresponding to the peak value.
Compared with the background technology, the technical scheme of the invention adopts a pupil division scheme in technical effect, and the scheme obtains important aspects of improving the detection of the signal change rate, such as the incident field intensity, the pupil division, the field of view of the optical collimation focusing element and other related parameters through the analysis of an optical system, thereby designing and optimizing the detection scheme and obviously improving the change detection rate of the reflected light.
Drawings
Fig. 1 is an overall operation schematic diagram of an acousto-optic measurement system in the prior art.
Fig. 2 is a schematic diagram of a detection optical path structure for performing echo measurement according to the prior art.
FIG. 3 is a schematic diagram of the time difference between two echo measurements according to the prior art echo measurement;
fig. 4 is a schematic diagram of an optical path structure of an acousto-optic measurement system according to the prior art.
FIG. 5 is a schematic diagram of the optical path structure of an acousto-optic measuring device implemented in accordance with the present invention;
FIG. 6 is a schematic diagram of one embodiment of a pupil splitter implemented in accordance with the present invention;
FIG. 7 is a schematic diagram of pupil segmentor imaging information implemented in accordance with the present invention;
FIG. 8 is a diagram showing the correspondence between spots that do not produce pupil division and reflection angle variations;
in all the figures, the same reference numerals denote the same features, in particular:
the optical detection device comprises a pump light source 1, an incident pump light 1a, a reflected pump light 1b, a film to be detected 2, an upper surface 3a, a lower bottom surface 3b, a deformation region 4, an incident light beam 5a, a reflected light 5b, a detection module 6, a first pupil divider 7, a second pupil divider 8, a first lens group 9, a second lens group 10 and a detector 11.
Detailed Description
It is to be understood that the following are many different embodiments or examples of the different features of the present embodiments. Specific examples of components and arrangements are described below to simplify the illustrative embodiments. These are, of course, merely examples and are not intended to limit the embodiments.
According to one embodiment of the present invention, the present invention provides a device for obtaining a detection change of reflected light in acousto-optic detection, which can significantly improve the measurement accuracy of detecting an angle change of light and significantly improve the measurement signal-to-noise ratio.
According to the device for detecting the angle change of the reflected light, as shown in fig. 5, an incident beam 5a enters a pupil splitter 7 at an included angle between the incident direction of the incident beam 5a and the vertical direction of the surface 3 of the film 2 to be detected, and then is converged and collimated by a lens assembly 9 to be obliquely incident on the sample, and the reflected light 5b after reflection passes through another lens assembly 10 and then passes through another pupil splitter 8 to reach a detector 11 on a deformation region 4 formed in the surface 3 of the sample 2 due to the pumping laser 1, so that the measurement result of the sample 2 is obtained by performing correlation analysis on the detected light.
The pupil splitter 7 splits the field intensity of the incident beam 5a to enable the incident beam 5a to form a first field intensity distribution on a first surface of the pupil splitter 7, and the lens group 9 arranged behind the optical path of the pupil splitter 7 collimates and converges the incident beam with the first field intensity distribution and then obliquely enters the surface of an object to form a reflected beam 5b with a second field intensity distribution; the other lens group 10 receives the collimated reflected light beam 5b which can be received in the self field range on the surface of the other pupil splitter 8, and forms a third field intensity distribution, the obtained third field intensity distribution characteristic is close to the first field intensity distribution characteristic, because the pupil splitter 7 and the other pupil splitter 8 have the same aperture function splitting, after the other pupil splitter 8 receives the reflected light beam with the third field intensity distribution, the first surface of the other pupil splitter 8 forms a fourth field intensity distribution and reflects the fourth field intensity distribution to the detector 12, and the detector 12 is used for detecting the reflected light beam after passing through the pupil splitter 8 to obtain the light intensity of the reflected light beam. Since the pump light source 1 forms an echo in the sample 2, the echo propagates to the deformation region 4, and interferes with the incident light beam 5a having the second field intensity distribution to form a reflected light beam 5b, and thus the reflected light beam 5b after passing through the pupil divider 7 is also interfered by the echo, the detector 10 can detect the time-dependent light intensity change caused by the echo; and the analysis device analyzes the reflected light beam change information with the fourth field intensity distribution in the analysis time interval to obtain the reflected light beam signal change.
Preferably, the first lens group and the second lens group form a light path collimation system, the first pupil splitter is arranged at the entrance pupil position of the light path collimation system, and the second lens group is arranged at the exit pupil position of the light path collimation system, because the pupil splitter 7 and the other pupil splitter 8 have the same aperture function, the obtained third field intensity distribution characteristic is close to the first field intensity distribution characteristic, so that the image of the pupil splitter 7 is superposed on the pupil splitter 8 or slightly shields and misplaces, after the change of the signal caused by the photoacoustic disturbance, the superposed or slightly misplaced signal can change, and by capturing the signal change information in the time interval, a more accurate detection result can be obtained.
For the above optical system for integrally measuring the angle change of the reflected light, the pump light source 1 in the related optical component is also called an excitation light source, except that Nd: light sources other than YAG lasers can be used to optically excite the film, and in particular embodiments, the lasers can also include Nd: YLF, ions (e.g., argon and krypton), ti: sapphire, diode, C0 2 Holmium, excimer, dye and metal vapor laser, etc., the pumping light source 1 is used for generating a deformation region 4 on the surface of a sample, and the wavelength, the generated laser pulse energy source, the period and the parameters of the beam waist can be determined according to the characteristics of the film of the sample 2And the characteristics thereof. In other studies, the pump light source 1 is generally converted into a light source with a diffraction pattern incident on the surface of the sample 2 by disposing a diffraction element behind the pump light source 1, and on the basis of this, unlike the bulge generated by the focused light spot, the deformation corresponding to the diffraction pattern is generated, and the change of the generated acousto-optic effect is more complicated and is also more susceptible to interference and changes.
In addition, in the embodiment of the solution according to the present invention, the type of the pump light source 1 and whether the pump light source is consistent with the incident angle of the probe incident light are not strictly limited, and in the whole optical detection system, the pulse of the pump light is usually collected at the same time to be used as a reference signal source for pumping and detecting the trigger of the pump light and the probe incident light 5 a.
Similarly, a light source other than a diode laser, similar to the pump light source above, may be selected as the detection laser, and the pulsed light source that can be used to generate the incident beam includes a Q-switch Nd: YAG, nd: YLF, ti: sapphire, diode, C0 2 Holmium, excimer, dye and metal vapor lasers, and the like. The incident detection light 5a involved in the design scheme of the present invention has strong adaptability to the wavelength range, and is not strictly limited, but the proposed requirement for the collimation of the incident detection light 5a is high, so that the design is balanced with the field of view of other optical elements in the optical system.
As one of the important improvements of the present invention, a pupil splitter 7 and a pupil splitter 8 are used in the detection optical path, wherein in the above pupil splitting scheme, the pupil splitter 7 is first required to be an optical element having at least two light-passing parts for limiting the light flux with respect to the incident light 5a, and the light-passing parts may be a one-dimensional structure (x-horizontal splitting or y-vertical splitting or oblique splitting of the incident light 5 a), or a two-dimensional structure (formed by any shape of grid-type splitting or any pattern-type splitting of the incident light 5 a), and may be a uniform splitting or a non-uniform splitting, which all have the same principle to improve the signal-to-noise ratio. It is preferable that the pupil splitter 7 has a beam splitting structure as many as possible in the spot direction with respect to the incident light 5 a. Further, the pupil splitter 8 is an optical element having at least two light passing portions for restricting the light flux with respect to the reflected light 5b, and the light passing portions may be a one-dimensional structure (x-lateral division or y-longitudinal division or oblique division of the reflected light 5 b), or a two-dimensional structure (any shape of grid division or any pattern division of the reflected light 5 b), and may be a uniform division or a non-uniform division, both of which have the same principle of improving the signal-to-noise ratio, wherein the pupil splitter 8 preferably has as many divided structures as possible in the spot direction with respect to the reflected light 5 b.
As shown in fig. 6, in one embodiment of the pupil splitter according to the present invention, the pupil splitter has a structure in which the light passing portion and the shielding beam portion are strip-shaped, the entire pupil splitter 7 is a disk-shaped structure with a diameter D, the light passing portion is a strip-shaped through hole, and the shielding beam portion is a non-light-tight material, in this embodiment, the periodic strip-shaped structure in which the light passing portion and the shielding beam portion alternate is a light passing width a, the width of the shielding beam portion is b, and the entire periodic structure is a width D (D = a + b), after the incident detection light 5a passes through the pupil splitter 7, the pupil splitter 7 converges on the deformation region 4 after passing through the lens group 9, and is finally received by the detector after being reflected by the thin-film structured light, the reflected light 5b changes due to acoustic disturbance of the deformation region 4, which first change is reflected by the image of the pupil splitter to a certain degree of deformation, the second aspect is reflected by the image of the pupil splitter at the imaging region, and the image of the pupil splitter 7 is reflected by the position deviation of the detector, which is more accurately detected as the optical spot deviation, and the optical spot information is obtained after the disturbance.
Further preferably, the reflected light 5b passes through another pupil splitter 8, the other pupil splitter 8 is a structure having a light-passing part and a light-shielding part in a strip shape, the whole pupil splitter 8 is a disc-shaped structure with a diameter D, the light-passing part is a strip-shaped through hole, the light-shielding part is a non-light-tight material, the periodic strip structure of the light-passing part and the light-shielding part in alternation is a light-passing width a, the width of the light-shielding part is b, the whole periodic structure is a width D (D = a + b), the reflected light 5b passes through the lens group 10 and then collimates and irradiates the pupil splitter 8, preferably, the pupil splitters 7 and 8 are similar in structure, the corresponding light-passing parts are the same in shape and are in proportional relationship in size, and since the lens groups 9 and 10 also preferably are the same mutually symmetrical optical elements in the optical path system, the image of the pupil splitter 7 is superimposed on the pupil splitter 8 or slightly misaligned in the shielding, and after the change of the photoacoustic disturbance-generated signal, the image signal is slightly overlapped or slightly misaligned in the pupil splitter, so that the image information can be analyzed to obtain more information.
Of course, in the above case, the pupil dividers 7 and 8 are preferably of a symmetrical structure, and the two optical elements may be of an asymmetrical structure, in which case, the image of the pupil divider 7 just intersects with the light-passing portion and the light-limiting portion of the pupil divider 8 for outgoing light to form a pattern image with two-dimensional information, and such an asymmetrical structure may increase process difficulties in device fabrication.
Further, where the positions of the pupil splitter 7 and the lens group 9 are selected so as to minimize the spot of the split incident probe light 5a on the sample surface, the blurred imaging out of focus significantly increases the difficulty of the imaging pattern analysis. Similarly, the positions of the pupil divider 8 and the lens assembly 10 are selected to take the priority that the diffraction fringes on the sample surface are fourier transformed back to the appearance of the pupil divider 7 to be clearly imaged on the second surface of the pupil divider 8, so that the imaging blur can significantly increase the difficulty of image pattern analysis.
Furthermore, in order to improve the signal to noise ratio, the field intensity distribution of the incident detection light beam or the visual field range of the lens group is adjusted through theoretical derivation, the field intensity distribution of the target emergent detection light spot can be modulated, and the signal to noise ratio of the detector is improved. The incident beam 5a passes through the pupil splitter 7 to generate a diffraction coherent light on the sample surface, which is a Fourier transform, i.e. the field intensity distribution of the incident beam 5a on the second surface of the pupil splitter 7 is U (x) 0 ,y 0 ) The field intensity distribution of the incident light beam 5a on the first surface (back surface) of the pupil splitter 7 is a first field intensity distribution U (x)′ 0 ,y′ 0 ) Then, the incident beam 5a is divided by the pupil divider 7, and the field intensity distribution on the surface of the deformation region 4 after being converged by the lens group 9 is a second field intensity distribution U (x) 1 ,y 1 ) Namely:
modulating the aperture function A (x) of the pupil splitter 7 0 ,y 0 ) The field intensity distribution of the incident beam 5a on the surface of the deformation region 4 can be obtained as U (x) 1 ,y 1 ) The lens group 10 distributes part of the field intensity in the visual field range U (x) 1 ,y 1 ) Is received, the field intensity distribution of the reflected light beam 5b formed as reflected to the second surface of the further pupil splitter 8 is the third field intensity distribution U (x' 2 ,y′ 2 ) Its field strength distribution would be approximated to a first field strength distribution U (x ') of the incident light beam 5a passing through the first surface of the pupil divider 7' 0 ,y′ 0 ) Since the pupil dividers 7 and 8 have the same aperture function A (x) 0 ,y 0 ) By modulating the aperture function A (x) of the pupil splitter 8 0 ,y 0 ) It is possible to realize that the fourth field intensity distribution U (x) of the first surface (rear surface) of the pupil splitter 8 is obtained 2 ,y 2 ). And a second field strength distribution U (x) 1 ,y 1 ) Will be interfered by the influence of the echo on the surface of the object, and form a third field intensity distribution which changes along with the time dependency of the echo return, the third field intensity distribution and the aperture function A (x) of the pupil splitter 8 0 ,y 0 ) Then superposition dislocation is generated to obtain a fourth field intensity distribution U (x) of the high signal-to-noise ratio signal which changes along with the time correlation of the echo 2 ,y 2 ) This signal will be received by the detector 11.
Further, the original field intensity distribution of the incident beam at the second surface of the pupil splitter 7 is U (x) 0 ,y 0 ) The function of the passage aperture is A (x) 0 ,y 0 ) After pupil splitter 7 of pupil splitter 7, a first field strength distribution U (x' 0 ,y′ 0 ) Is composed of
The incident beam 5a reaches the surface of the deformation region 4 with a second field intensity distribution:
the incident beam 5a reaches the surface of the deformation region 4, and the second field intensity distribution is U (x) 1 ,y 1 ) The reflected light 5b within the visual field of the lens group 10 is collimated to the second surface of the pupil splitter 8 to form a third field intensity distribution of U (x' 2 ,y′ 2 ) Namely, it is
The reflected light beam 5b passes through a pupil splitter 8 based on the aperture function A (x) 0 ,y 0 ) Formed as a fourth field strength distribution U (x) 2 ,y 2 ) I.e. by
The reflected light beam 5b has a field intensity distribution of U (x) at the fourth surface of the pupil splitter 8 2 ,y 2 ) The formula deduces the conclusion: final signal U (x) 2 ,y 2 ) And U (x) 0 ,y 0 )、A(x 0 ,y 0 ) The field of view of the lens group 9 and the field of view of the lens group 10 have definite physical relationships with the aim that
And (4) maximization. Where θ is the angle change of the reflected probe light 5b generated by the echo signal and s is the receiving area of the detector, since
And U (x) 0 ,y 0 )、A(x 0 ,y 0 ) The field of view of the lens group 9 and the field of view of the lens group 10 are related, and the aperture function A (x) of the pupil splitter 7 is used 0 ,y 0 ) It is easier to modulate.
As shown in FIG. 7, for the pupil division scheme of the present invention, after the pupil divider 7 and the pupil divider 8 shown in FIG. 6 are used, the final signal acquired by the detector 11 is a fringe image with alternating light and dark, and the signal change rate after pupil division is
As shown in FIG. 8, for the prior art scheme in which pupil division is not performed, the signal change rate
Wherein: eta or
Since the intensity distribution of the light is Gaussian distribution, eta > eta will be more obviously seen as a result 0 ；
Therefore, the signal jitter detected by the pupil division scheme detector of the invention is obvious, and the signal jitter detected by the detector under the condition of no division is small in amplitude and is not easy to identify.
In addition, the main core of the pupil dividers 7 and 8 is that the pupil is divided by more than or equal to 2, the specific optical parameters and process consistency of the pupil dividers 7 and 8 can be optimally designed and solved according to the practical application, the manufacturing materials can be prepared according to the optical process conditions, and the reflection effect and other factors in the optical system are considered, the surface or the back surface of the pupil dividers 7 and 8 are further preferably coated with a film to reduce the influence of the diaphragm reflection on the detection light 5c, or a filtering element is designed according to the diffraction pattern possibly generated at the diaphragm edge, and the design of keeping the 1-level fringe and the like can be further designed according to the core. Meanwhile, the diaphragm can be designed in a mode of adjusting the size of the pupil so as to conveniently carry out multiple measurements to reduce the disturbance and the error of the measurement result caused by the hardware of the optical system, and in addition, the fixing and adjusting equipment of the diaphragm can be designed according to the condition in consideration of the influence of the stability of the optical system.
The lens groups 9 and 10 are optical element combination systems, and perform collimation on an optical path, and the optical lens can achieve corresponding optical functions, and the specific arrangement of the optical lens is not strictly limited. In addition, a gain element for light intensity is arranged on the light path to compensate energy loss caused by the diaphragm, and the design can be expanded according to specific conditions.
The samples that can be monitored using the methods and apparatus of the present invention can be bulk (e.g., a solid such as a metal or semiconductor), thin film (e.g., a polymer, semiconductor or metal film), fluid, surface or exhibit acousto-optic time perturbation effects. Typical samples include metal films used in the semiconductor industry, such as aluminum, tungsten, titanium: tungsten, titanium or oxide films, and the like. Material properties that may be determined in these samples include mechanical, physical (e.g., thickness), elastic, (depth dependent and/or anisotropic) diffusion, adhesion-based, thermal (e.g., thermal diffusion) and adhesive properties associated therewith. As shown in fig. 7, when the diaphragm is divided into more image segments, the extracted information has more dimensions, for example, the change of the angle of the reflected light can be detected by the movement of the position change of the diaphragm image, and the distortion or the change of the shape of the image therein may mean the influence caused by the optical characteristics of the deformation region 4, and when the divided patterns are more, the common features and specific features can be extracted more, so that the scheme used in the invention obtains higher analysis precision in the subsequent computer analysis of the imaging light.
According to another embodiment of the present invention, there is provided a method for obtaining a change in reflected light detection in acousto-optic detection, the method including:
the method comprises the steps that a first pupil divider is used for dividing the incident light beam into field intensity, so that the incident light beam forms a first field intensity distribution on a first surface of the first pupil divider;
converging an incident beam with a first field intensity distribution to the surface of the object to form a reflected beam with a second field intensity distribution;
receiving the reflected beam having the second field strength distribution and collimating to form a reflected beam having a third field strength distribution;
receiving the reflected light beam with the third field intensity distribution by using a second pupil divider for field intensity division, so that the reflected light beam with the third field intensity distribution forms a fourth field intensity distribution on the first surface of the second pupil divider, wherein the first pupil divider and the second pupil divider have the same aperture function division;
and acquiring a reflected light beam with a fourth field intensity distribution, and analyzing the reflected light beam change information with the fourth field intensity distribution in a time interval. The implementation principle and technical effect of the method are similar to those of the device, and are not described in detail herein.
According to another embodiment of the present invention, there is provided a film thickness measuring apparatus including:
the pump light source bursts a plurality of excitation sources from the upper surface to the lower bottom surface of the film to be detected at a time point so as to enable the upper surface of the film to be detected to generate at least one deformation area;
providing a device for detecting the change of the reflected light beam, and acquiring the change information of the signal intensity peak value of the polarized reflected light beam 5b' corresponding to the deformation area;
and the calculating unit is used for calculating the thickness of the film to be measured according to the time interval corresponding to the peak value. The implementation principle and technical effect of the device are similar to those of the device for detecting the change of the reflected light beam, and are not described in detail herein.
It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.
Claims (10)
1. An apparatus for detecting changes in reflected light, the apparatus comprising:
at least one detection light source for generating an incident light beam (5 a);
at least one first pupil divider (7) arranged after the detection light source optical path for field intensity dividing the incident light beam (5 a) such that the incident light beam (5 a) forms a first field intensity distribution at a first surface of the first pupil divider (7);
the first lens group (9) is arranged behind the optical path of the first pupil divider (7) and is used for collimating and converging the incident beam with the first field intensity distribution to obliquely enter the surface of the to-be-measured object so as to form a reflected beam (5 b) with a second field intensity distribution;
the second lens group (10) is arranged on the reflection light path and is used for receiving the reflection light beam with the second field intensity distribution in the field range and collimating the reflection light beam to form a reflection light beam with a third field intensity distribution;
a second pupil divider (8) arranged behind the optical path of the second lens group (10) and used for receiving the reflected light beam with the third field intensity distribution for field intensity division, so that the reflected light beam with the third field intensity distribution forms a fourth field intensity distribution on the first surface of the second pupil divider (8), and the first pupil divider (7) and the second pupil divider (8) have the same aperture function;
and the detector (11) is used for acquiring the reflected light beam with the fourth field intensity distribution and analyzing the change information of the reflected light beam with the fourth field intensity distribution in a time interval.
2. The apparatus for detecting the change of the reflected light according to claim 1, wherein the first lens group (9) and the second lens group (10) constitute an optical path collimating system, the first pupil splitter (7) is disposed at an entrance pupil position of the optical path collimating system, and the second lens group (10) is disposed at an exit pupil position of the optical path collimating system.
3. The apparatus for detecting changes in reflected light according to claim 1 or 2, wherein the first pupil splitter (7) is provided with a plurality of light-transmitting structures of a first type and a plurality of light-transmitting structures of a second type, the light-transmitting structures of the first and second types having a difference in luminous flux such that an incident light beam (5 a) is perturbedly split by the light-transmitting structures of the first and second types into the incident light beam having the first field strength distribution.
4. The apparatus for detecting changes in reflected light as claimed in claim 3, wherein the second pupil splitter (8) is provided with a plurality of light-transmitting structures of a third type and a plurality of light-transmitting structures of a fourth type, which have a difference in luminous flux, such that the reflected light beam having the third field strength distribution is further perturbed into the reflected light beam having the fourth field strength distribution.
5. The apparatus for detecting a change in reflected light according to claim 4, wherein the first-type light-transmitting structures and the third-type light-transmitting structures correspond to each other one by one, and the shapes of the first-type light-transmitting structures and the third-type light-transmitting structures that correspond to each other are the same.
6. The apparatus for detecting a change in reflected light according to claim 4, wherein the field of view adjustment of the first lens group (9) is realized by arranging a constituent structure of the first lens group (9) so that the image of the first pupil splitter (7) clearly illuminates the object to be measured; the field of view of the second lens group (10) is adjusted by configuring the second lens group (10) such that the reflected light beam (5 b) having the second field intensity distribution is collimated and enters the second pupil divider (8).
7. The apparatus for detecting a change in reflected light according to claim 4, wherein the first pupil divider (7) and the second pupil divider (8) are axisymmetric with respect to the incident optical path and the reflected optical path.
8. The apparatus for detecting changes in reflected light according to any of claims 4-7, wherein the plurality of first type light passing structures have different light passing patterns.
9. A method of detecting changes in reflected light, the method comprising:
field intensity division of an incident light beam (5 a) with a first pupil divider (7) such that the incident light beam (5 a) forms a first field intensity distribution at a first surface of the first pupil divider (7);
the incident light beam with the first field intensity distribution is collimated and converged to be obliquely incident to the surface of the to-be-measured object to form a reflected light beam (5 b) with a second field intensity distribution;
receiving the reflected beam having the second field strength distribution and collimating to form a reflected beam having a third field strength distribution;
receiving the reflected light beam with the third field intensity distribution by a second pupil divider (8) for field intensity division, so that the reflected light beam with the third field intensity distribution forms a fourth field intensity distribution on a first surface of the second pupil divider (8), wherein the first pupil divider (7) and the second pupil divider (8) have the same aperture function;
and acquiring the reflected light beam with the fourth field intensity distribution, and analyzing the reflected light beam change information with the fourth field intensity distribution in the time interval.
10. A film thickness measuring apparatus, comprising:
the device comprises a pumping light source (1) and a plurality of excitation sources, wherein the pumping light source bursts from the upper surface (3 a) to the lower bottom surface (3 b) of a film (2) to be detected at one time point so as to generate at least one deformation area on the upper surface of the film (2) to be detected;
providing the apparatus for detecting the variation of the reflected light according to any one of claims 1 to 8, and acquiring the variation information of the intensity peak of the polarized reflected light beam corresponding to the deformation region;
and the calculating unit is used for calculating the thickness of the film (2) to be measured according to the time interval corresponding to the peak value.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05141924A (en) * | 1991-06-17 | 1993-06-08 | Nikon Corp | Film thickness measuring device |
| US5486701A (en) * | 1992-06-16 | 1996-01-23 | Prometrix Corporation | Method and apparatus for measuring reflectance in two wavelength bands to enable determination of thin film thickness |
| WO2006027568A1 (en) * | 2004-09-07 | 2006-03-16 | Scalar Technologies Ltd | Method and apparatus for thin film metrology |
| JP2012018003A (en) * | 2010-07-06 | 2012-01-26 | Nikon Corp | Surface inspection method and surface inspection device |
| CN110907468A (en) * | 2019-12-09 | 2020-03-24 | 上海精测半导体技术有限公司 | Surface detection device and method |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN101358835B (en) * | 2008-08-13 | 2010-08-25 | 哈尔滨工业大学 | Super-resolution compound shade differential confocal measuring device and method |
| TWI425188B (en) * | 2009-08-31 | 2014-02-01 | Zygo Corp | Microscope system and imaging interferometer system |
| JP2014182239A (en) * | 2013-03-19 | 2014-09-29 | Olympus Corp | Super-resolution microscope |
| KR102134943B1 (en) * | 2013-09-16 | 2020-08-26 | 케이엘에이 코포레이션 | Ellipsometer apparatus for performing metrology of a semiconductor sample |
| US11846773B2 (en) * | 2017-10-27 | 2023-12-19 | 3M Innovative Properties Company | Optical system |
-
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05141924A (en) * | 1991-06-17 | 1993-06-08 | Nikon Corp | Film thickness measuring device |
| US5486701A (en) * | 1992-06-16 | 1996-01-23 | Prometrix Corporation | Method and apparatus for measuring reflectance in two wavelength bands to enable determination of thin film thickness |
| WO2006027568A1 (en) * | 2004-09-07 | 2006-03-16 | Scalar Technologies Ltd | Method and apparatus for thin film metrology |
| JP2012018003A (en) * | 2010-07-06 | 2012-01-26 | Nikon Corp | Surface inspection method and surface inspection device |
| CN110907468A (en) * | 2019-12-09 | 2020-03-24 | 上海精测半导体技术有限公司 | Surface detection device and method |
Non-Patent Citations (2)
| Title |
|---|
| 基于光瞳分割和角剪切的成像偏振光谱技术;唐茜等;《物理学报》;20121231;第61卷(第23期);230701-1至230701-10 * |
| 高分辨力分光瞳差动共聚焦传感技术研究;刘超等;《仪器仪表学报》;20170930;第38卷(第9期);第2225-2231页 * |
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