TW201420993A - Multi-function measurement system for thin film elements - Google Patents

Abstract

A multi-function measurement system for thin film elements is disclosed and comprises a light, a reference surface, a testing surface of thin film element, a light detector and a processor, the light emits a plurality of first lights and a plurality of second lights, the reference surface has a tilt, which can receive the first lights and generate the first reflecting lights, the testing surface of the thin film element receives the second lights and generating second reflecting lights, the first reflecting lights and the second reflecting lights form a plurality of interference lights, and the light detector is for receiving the plurality of interference lights, wherein a plurality of reflecting phase generating by the plurality of interference lights can be gained through adjust the tilt of the reference surface, and the processor can process according to the plurality of reflecting phase or the intensity of the second reflecting lights so as to obtain at least one of the rough sketch, the thickness or the other optical parameters of the testing surface of the thin film element.

Description

Multifunctional film component detector

The present invention relates to a thin film component detector, and more particularly to a multifunctional thin film component detector that uses an optical interferometer to measure the surface contour of a thin film component and optical constants such as thickness, refractive index, and extinction coefficient.

The measurement technology currently used for thin film components can only measure the thickness of a film or the surface profile of a thin film component, and it is impossible to measure both at the same time. For example, an ellipsometer commonly used for measuring the thickness of a thin film component has the disadvantage of a bulky instrument, and the ellipsometer only measures the thickness of the thin film component, and cannot measure the two-dimensional refractive index of the thin film and the uniformity of the surface thereof. This means that it is impossible to measure the surface profile of the film. In addition, if an optical force microscope or an atomic force microscope is used to measure the film, the sample to be tested is destroyed, which in turn affects the measurement accuracy.

On the other hand, the interferometer used to measure the surface profile of the film adopts a non-destructive measurement method, but its resistance to vibration is very poor, and it is easy to image to the measurement result due to the vibration factor, so generally Usually used as a laboratory test, it is difficult to use as a measurement tool on the production line.

Based on the above reasons, how to develop a shortcoming that can overcome the aforementioned measurement technology, and at the same time, can measure the thickness of the film component, surface contour and other measurement functions, and reduce the detection cost and increase of the product on the production line. The multi-function thin film component detector for measuring rate is an urgent problem to be solved.

The purpose of the present invention is to provide a multi-functional thin film component detector which uses a spatial carrier frequency phase shift technique to introduce a tilt amount on a reference surface and transmit the optical path difference as phase shift information, thereby solving the conventional interferometer. Unable to solve the vibration problem.

Another object of the present invention is to provide a multifunctional thin film component detector that passes through the optical component configuration of the overall system and a specific calculation program to obtain the surface profile, thickness, extinction coefficient and refractive index of the surface to be tested of the thin film component. The optical constant has the functions of simplifying the overall optical architecture, reducing the cost of detecting the product on the production line, and increasing the measurement rate.

In order to achieve the above object, a broader aspect of the present invention provides a multifunctional thin film component detector comprising: a light source, a plurality of first rays and a plurality of second rays; and a reference surface having a tilt amount. The reference surface receives the plurality of first rays and generates the first reflected light; the surface of the film element to be tested receives the plurality of second rays and generates the second reflected light; the first reflected light and the second reflected light form a plurality of interference lights; a sensor for receiving the plurality of interference lights; and a processor coupled to the photo sensor; wherein, by adjusting the tilt of the reference plane to obtain a complex reflection phase generated by the complex interference light, the processor is based on the complex reflection phase Or calculating the reflectance of the object to be tested to obtain at least one of a surface profile, a thickness, and an associated optical constant of the surface to be tested of the film element.

Some exemplary embodiments embodying the features and advantages of the present invention will be in the latter paragraph. The description is described in detail. It is to be understood that the present invention is capable of various modifications in the various aspects of the present invention, and the description and drawings are intended to be illustrative and not limiting.

Figure 1 is a block diagram showing the multifunctional film element detector of the preferred embodiment of the present invention. As shown in FIG. 1 , the multi-functional thin film component detector 1 of the present invention is mainly composed of a light source 10 , a reference surface 11 , a surface to be tested 12 of a thin film component, a photo sensor 13 and an electronic device 19 , wherein the light source 10 A plurality of light rays 100 are emitted, wherein the light collimating system 17 adjusts the plurality of light rays 100 to the parallel light 100', and divides the parallel light 100' into a plurality of first light rays 101 and a plurality of lines through the beam splitter 14 The second light ray 102, the reference surface 11, the reference surface 11 has an inclination amount, and is configured to receive the plurality of first light rays 101 and generate the first reflected light 111, and the surface to be tested 12 of the film element receives the plurality of second light rays 102 and generating second reflected light 121, and the first reflected light 111 and the second reflected light 121 form a plurality of interference lights 141, and the light sensor 13 is configured to receive the complex interference light 141, and then A processor (not shown) in the electronic device 19 transmits the tilting amount of the reference surface 11 to obtain a complex reflection phase generated by the complex interference light 141, and is processed by the processor according to the complex reflection phase or the surface to be tested 12 The intensity of the two reflected light 121 to correlate The simulation, calculation, and further, the surface profile of the surface to be tested 12 of the film element or the film thickness, refractive index, and extinction coefficient thereof are obtained.

In some embodiments, the multifunctional film component detector 1 of the present invention can be, but is not limited to, a dynamic interferometer. However, compared with the conventional interferometer, the multifunctional film component detector 1 of the present invention can be utilized. Spatial Carrier Phase Shifting (SCPS) technology utilizes reference plane 11 Tilt causes the optical path difference to be used as phase shift information, thereby solving the vibration problem that cannot be solved by conventional interferometers. In this embodiment, the light source 10 can be a wide-wavelength light source. For example, a 200W mercury lamp can be used as the white light source, but not limited thereto.

Referring to FIG. 1 , in the embodiment, the multi-functional thin film device detector 1 further includes components such as a beam splitter 14 , a dispersing element 15 , a polarizing plate 16 , a light collimating system 17 , and an imaging lens 18 , and is split. The mirror 14 is disposed between the light source 10 and the reference surface 11 and the surface 12 to be tested of the thin film element, but the composition of the multifunctional thin film component detector 1 is not limited to the components, and the composition and arrangement of the optical components therebetween The system may be changed according to the actual application situation, and is not limited thereto. For example, in one embodiment of the present invention, the main components such as the light source 10, the reference surface 11, the surface to be tested 12 of the thin film element, the photo sensor 13 and the electronic device 19 may be arranged in a straight line in sequence. It can be achieved that the tilting amount (Tilt) is introduced as the information of the four-step phase shift by the reference plane 11, and then the phase reduction is performed, and the influence of the vibration is minimized by the operation, and the film element can be further estimated to be tested. Surface contour, film refractive index, thickness and other information of surface 12. In contrast, the embodiment of FIG. 1 is another embodiment in which the light source 10 emits a plurality of light rays 100. In the figure, in order to make the structure clear, only the simplest line is taken as an example, and Without limitation, in the traveling path of the light 100, the optical path adjustment by the light collimating system 17 formed by the lenses 171 and 172 can be adjusted to converge and parallelly emit to form a plurality of parallel lights 100'. And the plurality of parallel light 100' sequentially enters the polarizer 16 and the dispersing element 15. The main purpose of the polarizer 16 is to make the parallel light 100' become dimmed to facilitate subsequent interference procedures. Yu Yi In some embodiments, the dispersing element 15 is disposed between the light source 10 and the beam splitter 14 . However, in other embodiments, the dispersing element 15 may also be disposed between the beam splitter 14 and the photo sensor 13 . The dispersion element 15 is placed in the light travel path in accordance with the actual application. In addition, the dispersing element 15 can be an element such as a filter, a grating, a hologram element, an acousto-optic modulator, etc., and is not limited thereto, and its function is to distinguish the respective wavelength components of the light. Taking the embodiment as an example, the dispersing element 15 may be a narrow band filter, and the light wave output from the light source 10 is transmitted through the dispersing element 15 to be a light source of a Gaussian wave type spectrum, so as to constitute an interferometric measuring system with a low coherence length. The multi-interference phenomenon between the optical components in the system of the multi-functional thin film component detector 1 can be effectively reduced, and the influence of the interference noise on the measured value is reduced.

Referring to FIG. 1 , as shown in the figure, when the light 100 emitted by the light source 10 passes through the light collimation system 17 to form parallel light 100 ′, and then enters the beam splitter 14 through the polarizer 16 and the dispersing element 15 , The first light ray 101 and the second light ray 102 are separated into different paths by the beam splitter 14 , and the first light ray 101 is guided to the reference surface 11 , and the second light ray is guided to the film element to be tested. In some embodiments, the reference surface 11 can be a standard flat glass, but not limited thereto. As for the surface 12 to be tested of the thin film element, it can be a multilayer film or a single layer structure. Not limited to this. And, when the first light 101 enters the reference surface 11 and generates reflection, the first reflected light 111 is generated. Similarly, the second light 102 entering the surface to be tested 12 of the thin film element is likely to generate the second reflected light 112. A reflected light 111 and the second reflected light 112 form an interference after the common path, that is, the interference light 141 is formed, at this time, by adjusting the tilt of the reference surface 11 The amount can reach a sufficient amount of phase shift, thereby reducing the error. Then, in the present embodiment, the interference light 141 is permeable to the imaging lens 18 to converge and enter the photo sensor 13. In this embodiment, the photo sensor 13 is a highly sensitive charge coupled device. (Charge Coupled Device, CCD), that is, the photo sensor 13 can be a camera or a CCD of a camera, but not limited thereto, which can record the interference image intensity of all pixels (Pixel) in an instant, and finally, Then, the electronic device 19, for example, a computer, but not limited thereto, performs related operations, and the phase shift can be restored to obtain the original phase data, and then the calculated surface 12 of the thin film component is solved after the calculation. Surface profile, film refractive index, extinction coefficient, thickness.

Please refer to FIG. 1 and FIG. 2 at the same time. As shown in FIG. 1 , in the structure of the multi-functional thin film component detector 1 , the light sensor is introduced after the tilt of the reference plane 11 in the X-axis direction is introduced. The interference strength of the two arms obtained in 13 can be expressed as follows:

I ₀ is the background intensity, and γ is the clarity of the stripes. ( x _n ) is the phase corresponding to each position.

will ( x _n ) is obtained by expanding the points on the X-axis relative to the first point:

The second-order higher-order term is regarded as small and negligible. Due to the introduction of the tilt amount, it can be known ( x ₁ ) is the amount of phase change fixed for any two adjacent pixels, expressed as Δ _Tilt , and (2) can be rewritten as:

As shown in FIG. 2, it is a light intensity diagram of the light sensor of the multifunctional film component detector of the present invention, wherein the light intensity sensed on the CCD of the photo sensor 13 is used in this system. As shown in the figure, and its interference intensity is as follows:

The four equations listed above are the four-step phase shift interference intensity of this case, which can be approximated. ( x ₁ ), and the amount of phase shift can be calculated from the four-step phase. Therefore, the average phase shift on the X-axis can be transmitted to make the calculated error smaller. Through this calculation, the error can be minimized, so it can minimize the impact of vibration, that is, the space carrier frequency phase shifting technology used in this case is a vibration-resistant optical measurement system.

As described above, the phase reduction method used in the present case is to introduce a tilt (Tilt) amount on the reference plane 11 as the information of the four-step phase shift, and then perform phase reduction. Wherein, since the amount of tilt is a phase shift according to spatial linearity, any four adjacent interference intensities can be regarded as a set of four-step phase information on one axis, and the phase shift of each group is fixed. But unknown, so the Carré Algorithm algorithm is needed for phase and phase shift calculations.

Referring to FIG. 3, as shown in the figure, since the surface of the optical coating on the surface 12 to be tested is undulating, it is assumed that the adjacent four surfaces are smooth and the phase values are similar, so I ₁ is taken. , I ₂ , I ₃ , I ₄ are a set of four-step phase shifts, and the calculated phase is Φ ₁ ; I ₂ , I ₃ , I ₄ , and I ₅ are a set of four-step phase shifts, and the calculated phase is For Φ + △ and so on, it is Φ +2 △, Φ + ( N -1) △ Φ _N + ( N -1) △, so the calculated phase will still have a phase shift of inclination (Δ), so Must be removed.

The following are the individual interference intensities on the phase calculation axis:

△ is the unit tilt amount introduced on the calculation axis

Next, the calculation of phase Φ and phase shift Δ is performed by the Carré Algorithm algorithm and expressed as follows:

Thus, the numerical information of the phase difference to be obtained in the present case can be calculated. Since the phase calculation is based on one axis direction, in this case, the X-axis is used as the phase calculation direction. The phase calculation must be performed with the Carré Algorithm algorithm. The initial phase can be obtained by using the arctangent function. Value Φ , then Φ falls on Then, the phase is corrected again, so that Φ is returned to the four quadrants of the polar coordinates, Φ [0, 2π], the correction rule of the phase is shown in the following table:

The values of Sine and Cosine are respectively

At this time, Φ is the phase of a wrap, and then the unwrapping action is performed to obtain the correct phase.

In the present embodiment, as described above and as shown in FIG. 1, when the parallel light 100' emitted by the light source 10 is split into two lights by the beam splitter 14, one of the arms serves as a first reflection of the reference light. The light 111 is reflected by the reference surface 11 and the other arm is reflected by the surface 12 to be tested of the thin film element to form the second reflected light 121. The first reflected light 111 and the second reflected light 121 form interference after the common path. By using the interference pattern of the two arms for phase reduction, multiplying by the wavelength λ and dividing by 4 π , the surface contour of the surface to be tested 12 of the thin film element can be obtained.

In addition to the surface profile of the surface to be tested 12 of the aforementioned film element, if the reflectance of the surface 12 to be tested of the film element is to be measured, the reference arm (ie, one side of the reference surface 11) can be covered. The measurement of the reflection intensity of the surface 12 to be measured of the film element to be measured is compared with the reflection intensity of a sample having a known reflectance when it is placed on the surface 12 to be tested, and the measurement is known. The reflectance value of the surface to be tested 12 of the film element.

As for measuring the thickness measurement of the film of the surface to be tested 12 and the numerical data of the refractive index, the measurement result of the reflectance or the reflection phase can be used, and the fitting of the numerical algorithm is used to obtain the refractive index and thickness information. For the calculation method, please refer to Fig. 4 and the following description: As shown in Fig. 4, where 122 is the phase obtained by the blank surface of the film element to be tested 12 without the coating, and 121 is the thickness of the plating. The phase obtained for the coating of d. Through the coated phase 121, the reflection phase Φ _{R of the} film, the surface contour phase undulation Φ _{h 1} and the phase difference π of the dense medium can be derived; and the phase of the blank substrate 122 is the optical path difference caused by the film thickness. And the surface contour phase fluctuates Φ _{h 2} .

The refractive index of n _{j is the} refractive index of the jth layer, and the refractive index of n _{s is the} refractive index of the substrate. δ _j = 2πn _j d _j /λ _i . d _j is the thickness of the jth layer, and λ _i is the wavelength of the ith measurement. If the single layer film j=1, the reflection coefficient is:

The reflectance of the surface to be tested 12 of the film element is:

As can be seen from the above, the reflection phase and reflectance of the surface 12 to be tested of the film are a function of refractive index, thickness, and wavelength.

And because the refractive index values corresponding to different wavelengths are different, the refractive index is expressed by a Western program:

The surface contour formulas on both sides are as follows:

Subtract the phase measured on both sides to obtain:

Wherein Φ _R can be obtained by the formula (18).

Then match the reflection intensity information:

Since the measurement is known to be n _s , λ . Therefore, using multi-wavelength measurement, the phase difference between the coating and the blank substrate is obtained for each wavelength, and the reflectance of each wavelength and the measured value of the reflection phase are brought into the algorithm, and (22), (23) Calculate the corresponding solution found by the algorithm, and then establish the expression of the rating function as follows:

It is a sum of the difference between the measured value and the calculated value of each wavelength, and when the fitness value converges to the minimum value, the calculus can be calculated The parameter values of the refractive index, extinction coefficient and thickness of the surface 12 to be tested of the film element are obtained.

From the foregoing numerical calculation process, it can be understood that the reference device 11 is tilted by the spatial carrier phase shifting (SCPS) technique through the system setting of the multifunctional thin film component detector 1 of the present invention (Tilt). The resulting optical path difference is used as the phase shift information, which can smoothly solve the vibration problem that the conventional interferometer cannot solve. In addition, with the subsequent calculation program, the optical of the multi-functional thin film component detector 1 can be simplified. The number of components, and the beam splitter 14 only needs to use a general beam splitter, and there is no need to specifically use a polarization beam splitter. In addition, the light sensor 13 can only use a camera or a video recorder for general recording, and does not need to be specially used. The phase mask pixel camera, therefore, the multi-functional film component detector 1 of the present invention can simplify the overall system architecture and reduce the cost compared with the prior art, and can be applied to the solar cell, the semiconductor industry, the liquid crystal display, and the optical correlation. Various industries that require thin film components, such as lenses, filters, biomedical tests, conductive films or protective films, as thin film components Measurement purposes.

In summary, the multi-functional thin film component detector of the present invention utilizes the structure of the dynamic interferometer and introduces a tilt amount on the reference surface so that the first reflected light can be combined with the second reflected light of the surface of the thin film element to be tested. Interacting with each other, and then calculating the reflectivity of the object to be tested by receiving the reflected phase of the interference light or the intensity of the second reflected light by the photo sensor, and performing calculation by a processor with a specific calculation process to multifunctionally Optical constants such as surface profile, film thickness, refractive index, extinction coefficient, etc. of the surface to be tested of the film element were measured. In addition, the multi-functional thin film component detector of this case can effectively reduce the vibration problem of the interferometer, and can simplify the overall system architecture and reduce the system. Create and test costs and other advantages.

This case has been modified by people who are familiar with the technology, but it is not intended to be protected by the scope of the patent application.

1‧‧‧Multifunctional film component detector

10‧‧‧Light source

100‧‧‧Light

100’‧‧‧Parallel Light

101‧‧‧First light

102‧‧‧second light

11‧‧‧ reference plane

111‧‧‧First reflected light

12‧‧‧Determination of film elements

120‧‧‧second reflected light

121‧‧‧ coating

122‧‧‧ Blank substrate

13‧‧‧Light sensor

14‧‧‧beam splitter

141‧‧‧Interference light

15‧‧‧Dispersion components

16‧‧‧Polar piece

17‧‧‧Light collimation system

171, 172‧‧ lens

18‧‧‧ imaging lens

19‧‧‧Electronic devices

Figure 1 is a block diagram of a multifunctional film component detector of the preferred embodiment of the present invention.

Fig. 2 is a schematic view showing the light intensity of the photosensor shown in Fig. 1.

Fig. 3 is a view showing the amount of phase shift of the reference surface shown in Fig. 1 and the surface profile of the surface to be tested of the film member.

Fig. 4 is a schematic view showing the phase of coating of the surface to be tested of the thin film element shown in Fig. 1.

1‧‧‧Multifunctional film component detector

10‧‧‧Light source

100‧‧‧Light

100’‧‧‧Parallel Light

101‧‧‧First light

102‧‧‧second light

11‧‧‧ reference plane

111‧‧‧First reflected light

12‧‧‧Determination of film elements

120‧‧‧second reflected light

13‧‧‧Light sensor

14‧‧‧beam splitter

141‧‧‧Interference light

15‧‧‧Dispersion components

16‧‧‧Polar piece

17‧‧‧Light collimation system

171, 172‧‧ lens

18‧‧‧ imaging lens

19‧‧‧Electronic devices

Claims (9)

A multifunctional film component detector includes at least: a light source emitting a plurality of first rays and a plurality of second rays; a reference surface having an amount of tilt, the reference surface receiving the plurality of first rays and generating a a first reflected light; a surface of the film element to be tested, receiving the plurality of second rays and generating a second reflected light; the first reflected light and the second reflected light form a plurality of interference lights; a light sensor, And receiving a plurality of interference lights; and a processor connected to the photo sensor; wherein, by adjusting the tilt amount of the reference surface to obtain a complex reflection phase generated by the complex interference light, the processor is configured according to the The complex reflection phase or the intensity of the second reflected light is computed to obtain at least one of a surface profile of the film element to be tested, a film thickness, and a film-related optical constant. The multi-functional thin film device detector according to claim 1, wherein the light source is a wide-wavelength light source. The versatile film component detector of claim 1, wherein the versatile film component detector further comprises a beam splitter disposed on the light source and the reference surface, the surface of the film component to be tested. And a plurality of first rays of the light source are directed to the reference surface, and the plurality of second rays are directed to the surface to be tested of the film element. The multi-functional film component detector of claim 3, wherein the multi-functional film component detector further comprises a dispersing component disposed between the light source and the beam splitter, or the splitting mirror Between the photo sensor and the photo sensor. The multi-functional thin film device detector according to claim 4, wherein the dispersing element is at least one of a filter, a grating, a hologram element, and an acousto-optic modulator. The multi-functional film component detector of claim 5, wherein the multi-functional film component detector further comprises a polarizer disposed between the light source and the beam splitter for using the light source The parallel light emitted is adjusted to be the same dimming. The multi-functional film component detector of claim 3, wherein the multi-functional film component detector further comprises an imaging lens disposed between the beam splitter and the photosensor. The versatile film component detector of claim 1, wherein the photosensor is a camera or a camera charge coupled component. The multi-functional film element detector according to claim 1, wherein one of the film elements to be tested is a multilayer film or a single film structure.