JP2012141134A - Method for monitoring thin-film formation using dynamic interferometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of monitoring thin-film formation using a dynamic interferometer.SOLUTION: A method of realtime monitoring of thin-film growth that uses a dynamic interferometer is disclosed. A temporal phase change of a reflection coefficient of a growth thin-film stack is extracted through optical monitoring. The dynamic interferometer eliminates effects of vibration and air turbulence, and is used with a method for directly detecting a variable phase of the growth thin-film stack. The realtime reflection coefficient under vertical incidence of monitoring light can be obtained in the same manner as optical admittance, in conjunction with measurement of reflectance or transmittance, so that the coefficient is applicable to enhancement of error compensation on thin-film growth.

Description

  The present invention relates to an optical monitoring method for thin film formation, and more particularly to a thin film formation monitoring method using a dynamic interferometer.

  The optical monitoring method is generally considered to be an excellent method for manufacturing an optical filter, and a more precise optical monitor is required for manufacturing an expensive optical filter.

  In thin film stacking, the refractive index of the material usually changes, so that the preferred thickness of each layer is not the same as expected in the original design. For this reason, the end point of each thin film layer needs to be corrected.

  However, known monitoring methods do not solve this problem analytically. In most known monitoring systems for coating deposits, only transmittance and reflectance are measured. Transmittance or reflectance can reach local extremes when the current layer is grown to a quarter thickness of the monitoring wavelength.

  In most methods, extreme fold points are used to estimate the endpoint of each layer deposition. Other monitoring methods, such as ellipsometry and broadband spectrum monitoring, use computer algorithms to adjust the measured values to obtain the optical constant, which includes too many parameters, which are analytically This is because it is difficult to solve. There are no clearer rules to terminate deposition by these monitors.

  It is an object of the present invention to provide a method for monitoring thin film deposition. By using a new type of polarization interferometer, the phase and magnitude of the monitoring light normally reflected from the deposited thin film is obtained in real time, and the physical property changes of the thin film are also found analytically.

  The present invention employs a dynamic interferometer for thin film growth monitoring. It provides a reflection coefficient trajectory or equivalent optical admittance trajectory for monitoring and response error compensation. Changes in thickness and refractive index are also known for non-absorbing thin films. For endpoints near the left intersection of the real axes, a pi phase shift can be added to the measured phase and the optical admittance is recalculated to increase monitoring sensitivity.

The invention of claim 1 is the thin film monitoring method,
Providing a substrate with a thin film,
Measuring the reflected phase of the film through a pixelated phase mask image detection unit using a dynamic interferometer with a light source of low coherence length;
Using a polarization interferometer to split the low-coherence light from the light source into orthogonal orthogonal first and second linear polarizations;
These two linear polarizations are incident perpendicular to the substrate and the film, and the two linear polarizations are reflected by two interfaces on both sides of the substrate,
All reflected light is received by the pixelated phase mask image detection unit, and the reflected light beams interfere with each other while the difference in path length between these reflected light beams is less than the low coherence length,
Generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity;
Measure the transmittance of the thin film, calculate the non-absorbing reflectance of the thin film, or directly measure the reflectance of the thin film using a pixelated phase mask image detection unit,
Obtaining a reflection coefficient that matches the reflection phase and the reflectance at different times;
Calculating an equivalent admittance of the thin film corresponding to the reflection coefficient, calculating a thickness and a refractive index of the thin film by the equivalent admittance, and including the above steps, It is a thin film monitoring method.
According to a second aspect of the present invention, in the thin film monitoring method according to the first aspect, the pixelated phase mask image detection unit includes a photodetector including a birefringent crystal array aligned with a pixel array to which a polarizing plate is coupled. The thin film monitoring method is characterized by this.
The invention according to claim 3 is the thin film monitoring method according to claim 1, wherein the pixelated phase mask image detection unit includes a polarizing plate array aligned with a pixel array to which a quarter-wave plate is coupled. It is the thin film monitoring method characterized by including.
According to a fourth aspect of the present invention, in the thin film monitoring method according to the first aspect, the step of generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity is a pixel phase. A mask image detection unit receives all the reflected light and generates different phase shift inteferograms from which the dynamic interferometer The thin film monitoring method is characterized in that the reflection phase is obtained.
The thin film monitoring method according to claim 5, wherein the coherence length of the low coherence light is larger than the total optical thickness of the thin film and smaller than the optical thickness of the substrate. Yes.
According to a sixth aspect of the present invention, in the thin film monitoring method according to the first aspect, the step of generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity includes a phase shift algorithm. The thin film monitoring method is provided in order to obtain a reflection phase that matches the interference light by using.
According to a seventh aspect of the present invention, in the thin film monitoring method according to the first aspect, in the step of generating the interference light in the dynamic interferometer to obtain the reflection phase corresponding to the interference intensity, A thin film monitoring method is characterized in that a dynamic interferometer detects the interference light through the pixelated phase mask image detection unit.
The invention according to claim 8 is the thin film monitoring method according to claim 7, wherein the image detection result of the pixelated phase mask image detection unit includes a plurality of pixels, and four pixels are set as one unit. The thin film monitoring method is characterized in that each unit is recorded as a phase.
According to a ninth aspect of the present invention, in the thin film monitoring method according to the first aspect, the reflected first linearly polarized light passing through the substrate and the reflected second linearly polarized light form a plurality of reflected light beams, The path difference between the pair of reflected light beams where the two light beams interfere with each other is smaller than the coherence length when the path length difference between the two mirrors to the polarizing beam splitter is equal to the optical thickness of the substrate. It is a thin film monitoring method.
An eleventh aspect of the invention is the thin film monitoring method according to the tenth aspect, wherein each pair of light beams interferes with each other after passing through the polarizing plate.
The invention of claim 12 is the thin film monitoring method of claim 10, wherein a reference reflective surface is inserted on the substrate, the path difference is made equal to the distance between the reference surface and the back surface of the substrate, the reflection phase, A thin film monitoring method is characterized in that a surface contour having a thin film formation change is measured and monitored by interference of all light beam pairs.
A thirteenth aspect of the invention is the thin film monitoring method according to the first aspect, wherein the thin film coefficient at each time is recorded in order to form a trajectory of a thin film formation change in order to obtain a monitoring chart of the thin film reflection coefficient. It is a thin film monitoring method.
According to a fourteenth aspect of the present invention, there is provided a thin film monitoring method according to the first aspect, wherein an equivalent admittance at each time is formed to form a trajectory of a thin film formation change in order to obtain a monitoring chart of an equivalent admittance of the thin film. ) Is recorded, it is a thin film monitoring method.
According to a fifteenth aspect of the present invention, in the thin film monitoring method according to the fourteenth aspect, in the step of adding monitoring sensitivity at the growth end point on the left side of the locus, a phase shift of pi is added to the reflection phase, and the corresponding optical admittance is recalculated The thin film monitoring method is characterized by monitoring the monitoring sensitivity.

  The present invention provides a novel optical monitoring system instead of applying numerical adjustment and analytically obtains reflection coefficient, equivalent optical admittance, refractive index, and thin film stack thickness.

  It provides higher precision and more accurate error compensation in monitoring. It helps the operator to control the deposition more clearly, reduces the misjudgment of the deposition endpoint, and improves the yield.

1 is a schematic diagram illustrating a monitoring device according to a preferred embodiment of the present invention. FIG. 3 is a schematic diagram of a polarizing plate distribution on a pixelated phase mask camera according to a preferred embodiment of the present invention. FIG. 6 illustrates normal incidence light reflection in a substrate according to a preferred embodiment of the present invention. 3 is a flowchart according to a preferred embodiment of the present invention. FIG. 6 is a reference diagram showing that the sensitivity is improved by adding the phase shift of pi to the reflection phase and recalculating the corresponding optical admittance.

  The present invention will be further understood by the detailed description of the accompanying drawings, which do not limit the invention.

  The present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements.

  Please refer to FIG. The thin film monitoring apparatus 1 is installed outside the coating apparatus 12, which is connected to the coating chamber 100 of the coating apparatus 12. The thin film monitoring apparatus 1 includes a light source 103, a collimator 104, a dynamic interferometer 10, an imaging lens 115, a pixelated phase mask camera 116, a photodetector 120, and a processing unit 122.

  The photodetector 120 is disposed in the coating chamber 100 and the substrate 14 is also disposed in the coating chamber 100.

  The dynamic interferometer 10 is preferably a combination of a Fizeau polarization interferometer 101 and a Twyman-Green interferometer 102, but the invention is not limited to this embodiment. . Fizeau polarization interferometer 101 includes a beam splitter 113 and a quarter wave plate 114. The Twiman-Green interferometer 102 includes a polarizing plate 105, a polarizing beam splitter (PBS) 106, two quarter-wave plates 107 and 108, and two mirrors 109 and 110.

  The monitoring system is installed outside the coating chamber 100. As shown in FIG. 1, a Fizeau polarization interferometer 101 to which a pixelated phase mask camera 116 is coupled is used to extract the optical phase.

  The light is emitted from the light source 103 and then collimated by the collimator 104. The collimated light can pass through the polarizing plate 105, which is used to adjust the intensity ratio between two orthogonal polarizations.

  The polarizing beam splitter (PBS) 106 separates two orthogonal polarizations into different arms of the Twiman-Green interferometer 102. The two quarter-wave plates 107 and 108 are arranged around the polarizing beam splitter (PBS) 106 to convert S-polarized light reflected from one mirror 109 into P-polarized light, and another mirror 110. The P-polarized light reflected from the light is oriented to be converted to S-polarized light. The light coming from the two arms is recombined and leads to the Fizeau cavity, which is our substrate.

  In our case, the test surface 111 is located on the side on which the thin film is grown, and the other side of the substrate is the reference surface 112. The reflected light is directed to the quarter wave plate by the beam splitter 113.

  The quarter wave plate 114 in front of the camera converts the two polarized beams coming from the two arms of the interferometer into two orthogonal circular polarization states. The quarter-wave plate 114 assumes that the reflection coefficient phase of the thin film is obtained from the arc tangent function of the measured intensity rather than the inverse cosine form. It provides higher sensitivity than without a quarter wave plate.

  After passing through the imaging lens 115, the light beam goes to the camera. The camera 116 has a CCD array, and each pixel has a polarizing plate thereon, as shown in FIG. The test beam is left-handed circularly polarized with a phase of φL and the reference beam is right-handed circularly polarized with a phase of φR. Further, both beams are made incident on a linear polarizing plate arranged in an α angle direction with respect to the x axis.

そのうち、Φ（ｘ，ｙ）＝φＬ−φＲ、ＩＬ 及びＩＲ は左旋及び右旋円偏光ビームの強度である。 After passing through the polarizer, both the test beam and the reference beam are linearly polarized at an α angle, a phase offset of + α is added to the test beam, and a phase offset of −α is added to the reference beam. The two beams are thus collinear and form interference giving the intensity pattern shown in the following general formula (1).

Among them, Φ (x, y) = φL−φR, IL and IR are the intensities of the left-handed and right-handed circularly polarized beams.

  The linear polarizer acts as a phase shift device between the two beams and the phase shift 2α is equal to twice the orientation angle of the polarizer.

  As shown in FIG. 2, adjacent pixels of the camera have different alignment polarizers. There can be four different polarizers 201, 202, 203, 204 in one unit, which units are periodically distributed in the CCD array. There are four different polarizers on the camera at 0 °, 45 °, -45 °, 90 °, which generate four different phase-shifted interferograms at once for the phase-shift algorithm. . These phases can thereby be calculated simultaneously by a phase shift algorithm.

  In FIG. 3, the rays are spatially separated and depicted with a slight tilt, but they are perpendicular to the surface and are collinear in the surveillance system. The number in the cavity refers to the number of test surface reflections that each beam passes before exiting the cavity.

  Only paired beams whose paths match and are drawn with the same type of line interfere with each other because the light has a short coherence length. If we carefully adjust the translation stage of one arm of the Twiman-Green interferometer, the distance between the PBS 106 of the two mirrors 109, 110 can have a difference in the optical thickness of the substrate. Each successive reflection of the S-polarized beam from the test surface is coherent with the P-polarized beam that has undergone additional test surface reflections. Only beam pairs with almost the same path length have observable interference fringes, others are suppressed due to low coherence.

そのうちＲｒとＲｔはそれぞれ参考表面と試験表面からの反射率である。φは各干渉ビーム対における二つのビームの間の位相差である。 Paths that match S0 and P1, and S1 and P2 are drawn with the same type of lines (eg, S0 and P1 are drawn with broken lines, and S1 and P2 are drawn with dotted lines). The measured intensity is represented by the following general formula 2.

Of these, Rr and Rt are the reflectances from the reference surface and the test surface, respectively. φ is the phase difference between the two beams in each interference beam pair.

そのうち、Φは期待位相である。 The reflected phase from the test surface of the grown thin film is obtained by a four-step phase shift algorithm in a single camera frame to freeze the vibration effect.

Of these, Φ is the expected phase.

  Data obtained in several frames must be averaged to eliminate turbulence effects.

  The optical phase can be calculated in real time and the distance between the reference and test surfaces, i.e. the substrate thickness, should remain the same during the coating process, even though the two mirrors of the Twiman-Green interferometer Mechanical vibration can result in different tilts and shifts over time, which can change the path difference between the reference beam and the test beam and affect the accuracy of the calculated phase result.

  A portion of the test surface of the substrate must be blocked and kept uncoated as a reference area. Since light rays coming from the reference area and the test thin film area pass through a common path, the vibration effect can be canceled by subtracting the phase difference between the reference area and the monitoring area before film formation from that after film formation. In this way, the forward reflection phase of the thin film can be obtained.

  A photodetector for receiving a change in the intensity of the transmitted light is disposed below the coating apparatus. The magnitude of the reflection coefficient and the square root of the reflectance are further obtained. The reflectance is determined by the camera and Eq. It is measured by (2).

そのうち、φ及びθは反射係数の大きさと位相であり、ｎ０は発生手段の屈折率である。 After the magnitude and phase of reflection are obtained, the reflection coefficient of normal incidence light is known and the optical admittance can be calculated by the following relational expression.

Of these, φ and θ are the magnitude and phase of the reflection coefficient, and n0 is the refractive index of the generating means.

In other cases, the generating means is a substrate. Therefore, n0 is equal to the refractive index nS of the substrate. α and β are given by:

  For non-absorbing films, the change in refractive index and thickness at each instant can also be calculated.

αＥ及びβＥは、以前に形成された薄膜の等価光学アドミタンスの実及び虚の部分である。δは新たに形成された薄膜の光学位相厚さであり、ｎは対応する屈折率である。

Optical admittance can be described as follows.

αE and βE are the real and imaginary parts of the equivalent optical admittance of the previously formed thin film. δ is the optical phase thickness of the newly formed thin film, and n is the corresponding refractive index.

  We must choose a set of solutions where n and δ are positive. Thus, complete information regarding the instantaneous reflection coefficient, optical admittance, refractive index, and exact thickness of the growing thin film stack is observed through this optical monitoring system.

  The monitoring sensitivity of the reflection coefficient or optical admittance trajectory varies for each unit of optical phase thickness and should be analyzed in two parts, because the trajectory moves in both two orthogonal directions during film growth, Is the direction along the real and imaginary axes.

そのうちα及びβはそれぞれ以前の薄膜スタックの等価光学アドミタンスの実と虚の部分である。δは光学位相厚さであり、ｎは薄膜の屈折率である。 The following equation shows the sensitivity of the optical admittance trajectory. Sensitivity X and sensitivity Y indicate the real and imaginary parts of the optical admittance, respectively.

Α and β are the real and imaginary parts of the equivalent optical admittance of the previous thin film stack, respectively. δ is the optical phase thickness, and n is the refractive index of the thin film.

  Sensitivity is low at the growth endpoint on the left side of the locus circle. However, as shown in FIG. 5, if we simply add the phase shift of pi to the reflected phase and recalculate the corresponding optical admittance, the sensitivity can be greatly improved.

  Table 1 shows a comparison of the measurement results with the monitoring system and the ellipsometer. Their results are very close to each other.

  Please refer to FIG. The monitoring method of the present invention is used to monitor thin film formation in real time, and it is determined by real time monitoring whether or not the thin film coating is terminated.

  In step S100, the low-coherence light from the light source 103 is used to irradiate the substrate 14 in order to suppress false interference fringes. The mirrors 109 and 110 of the Twiman-Green interferometer 102 are adjusted so that the difference in length between the two arms is the optical thickness of the substrate, and only a specific beam pair is phase-matched to interfere with each other. It is supposed to be. This facilitates calculation of the reflection phase of the thin film. Since the adjustment method of the interferometer for obtaining the interference light more clearly is well known, no further explanation will be given here.

  In step S102, a phase calculation that matches the intensity measurement from the pixelated phase mask camera 116 is performed, the phase of the intensity measurement is solved, the inclination factor and the aberration of the intensity measurement are removed, and the image is captured by the pixelated phase mask camera 116. Average over 15 frames. In other words, the phase difference between the pair of interfering beams is solved, the phase tilt factor and aberrations are removed, and the data of multiple frames is averaged to remove the effect of turbulence on the phase.

  In step S104, the intensity and phase difference of the coating area and block area are recorded as the start phase difference and start intensity, respectively.

  In step S106, thin film formation is started.

  Then, step S108 is executed, and in step S108, the phase of the measurement from the pixelated phase mask camera 116 is solved, the measurement inclination and aberration are removed, and 15 or more frames from the pixelated phase mask camera 116 are averaged. To do.

  Then, in step S110, the transmittance and measurement phase difference between the coating area and the block area of the substrate are obtained in order to obtain the reflection phase of the thin film.

  In step S112, the start phase difference is compared with the measurement phase difference to obtain a reflection phase change, and the measurement intensity is compared with the start intensity. In other words, the reflected phase change of the grown thin film is obtained by subtracting the starting phase difference from the measured phase difference. The transmittance of the thin film is obtained by comparing the measured intensity with the starting intensity.

  Then, in step S114, the reflection coefficient or optical admittance of the grown thin film is calculated, and the locus is recorded as the thin film growth.

  In step S116, it is determined from the result of step S114 whether or not the trajectory has reached the end point of thin film formation. If the result is yes, next step S118 is executed. If the determination result is no, next step S108 is executed to continue monitoring the thin film formation.

  Finally, as step S118, the thin film formation is terminated.

  Furthermore, the real-time refractive index and thickness of the formed thin film can be obtained analytically. It provides a global and precise monitor for thin film device formation.

  The reflection coefficient trajectory and optical admittance trajectory as the film grows are thus monitored in this system. From these trajectories, the operator can directly find better error compensation than the transmission or reflectance trajectories of the thin film formation because they contain information on both the strength and phase of the thin film. is there.

  In addition, a method for increasing the sensitivity of optical admittance trajectory monitoring is also presented in the present invention.

  The above description is only an example of the present invention, and does not limit the scope of the present invention. Any equivalent changes and modifications that can be made based on the scope of the claims of the present invention are all described in the present invention. Shall belong to the scope covered by the rights.

DESCRIPTION OF SYMBOLS 1 Thin film monitoring apparatus 10 Dynamic interferometer 100 Coating chamber 101 Fizeau polarization interferometer 102 Twiman-Green interferometer 103 Light source 104 Collimator 105 Polarizing plate 106 Polarizing beam splitter (PBS)
107, 108 Quarter-wave plate 109, 110 Mirror 115 Imaging lens 116 Pixelated phase mask camera 120 Photo detector 122 Processing unit 113 Beam splitter 114 Quarter-wave plate 12 Coating device 14 Substrate

The invention of claim 1 is the thin film monitoring method,
Providing a substrate with a thin film,
Measuring the reflected phase of the film through a pixelated phase mask image detection unit using a dynamic interferometer with a light source of low coherence length;
Using a polarization interferometer to split the low-coherence light from the light source into orthogonal orthogonal first and second linear polarizations;
These two linear polarizations are incident perpendicular to the substrate and the film, and the two linear polarizations are reflected by two interfaces on both sides of the substrate,
All reflected light is received by the pixelated phase mask image detection unit, and the reflected light beams interfere with each other while the difference in path length between these reflected light beams is less than the low coherence length,
Generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity;
Measure the transmittance of the thin film, calculate the non-absorbing reflectance of the thin film, or directly measure the reflectance of the thin film using a pixelated phase mask image detection unit,
Obtaining a reflection coefficient that matches the reflection phase and the reflectance at different times;
Calculating an equivalent admittance of the thin film corresponding to the reflection coefficient, calculating a thickness and a refractive index of the thin film by the equivalent admittance, and including the above steps, It is a thin film monitoring method.
According to a second aspect of the present invention, in the thin film monitoring method according to the first aspect, the pixelated phase mask image detection unit includes a photodetector including a birefringent crystal array aligned with a pixel array to which a polarizing plate is coupled. The thin film monitoring method is characterized by this.
The invention according to claim 3 is the thin film monitoring method according to claim 1, wherein the pixelated phase mask image detection unit includes a polarizing plate array aligned with a pixel array to which a quarter-wave plate is coupled. It is the thin film monitoring method characterized by including.
According to a fourth aspect of the present invention, in the thin film monitoring method according to the first aspect, the step of generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity is a pixel phase. A mask image detection unit receives all the reflected light and generates different phase shift inteferograms from which the dynamic interferometer can then generate a phase shift inteferogram. The thin film monitoring method is characterized in that the reflection phase is obtained.
The thin film monitoring method according to claim 5, wherein the coherence length of the low coherence light is larger than the total optical thickness of the thin film and smaller than the optical thickness of the substrate. Yes.
According to a sixth aspect of the present invention, in the thin film monitoring method according to the first aspect, the step of generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity includes a phase shift algorithm. The thin film monitoring method is provided in order to obtain a reflection phase that matches the interference light by using.
According to a seventh aspect of the present invention, in the thin film monitoring method according to the first aspect, in the step of generating the interference light in the dynamic interferometer to obtain the reflection phase corresponding to the interference intensity, A thin film monitoring method is characterized in that a dynamic interferometer detects the interference light through the pixelated phase mask image detection unit.
The invention according to claim 8 is the thin film monitoring method according to claim 7, wherein the image detection result of the pixelated phase mask image detection unit includes a plurality of pixels, and four pixels are set as one unit. The thin film monitoring method is characterized in that each unit is recorded as a phase.
According to a ninth aspect of the present invention, in the thin film monitoring method according to the first aspect, the reflected first linearly polarized light passing through the substrate and the reflected second linearly polarized light form a plurality of reflected light beams, The path difference between the pair of reflected light beams where the two light beams interfere with each other is smaller than the coherence length when the path length difference between the two mirrors to the polarizing beam splitter is equal to the optical thickness of the substrate. It is a thin film monitoring method.
The tenth aspect of the present invention is the thin film monitoring method according to the ninth aspect, wherein each light beam pair interferes with each other after passing through the polarizing plate.
The invention of claim 11 is the thin film monitoring method of claim 10, wherein a reference reflective surface is inserted on the substrate, the path difference is made equal to the distance between the reference surface and the back surface of the substrate, the reflection phase, A thin film monitoring method is characterized in that a surface contour having a thin film formation change is measured and monitored by interference of all light beam pairs.
The invention of claim 12 is characterized in that, in the thin film monitoring method according to claim 1, the thin film coefficient at each time is recorded in order to form a trajectory of the thin film formation change in order to obtain a monitoring chart of the thin film reflection coefficient. It is a thin film monitoring method.
According to a thirteenth aspect of the present invention, there is provided a thin film monitoring method according to the first aspect, wherein an equivalent admittance at each time is formed in order to form a trajectory of a thin film formation change in order to obtain a monitoring chart of an equivalent admittance of the thin film. ) Is recorded, it is a thin film monitoring method.
According to a fourteenth aspect of the present invention, in the thin film monitoring method according to the thirteenth aspect, in the step of adding the monitoring sensitivity at the growth end point on the left side of the locus, a phase shift of pi is added to the reflection phase, and the corresponding optical admittance is recalculated. The thin film monitoring method is characterized by monitoring the monitoring sensitivity.

Claims (14)

In the thin film monitoring method,
Providing a substrate with a thin film,
Measuring the reflected phase of the thin film through a pixelated phase mask image detection unit using a dynamic interferometer with a light source of low coherence length;
Using a polarization interferometer to split the low-coherence light from the light source into orthogonal orthogonal first and second linear polarizations;
These two linear polarizations are incident perpendicular to the substrate and the film, and the two linear polarizations are reflected by two interfaces on both sides of the substrate,
All reflected light is received by the pixelated phase mask image detection unit, and the reflected light beams interfere with each other while the path length difference between these reflected light beams is less than the low coherence length,
Generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity;
Measure the transmittance of the thin film, calculate the non-absorbing reflectance of the thin film, or directly measure the reflectance of the thin film using a pixelated phase mask image detection unit,
Obtaining a reflection coefficient that matches the reflection phase and the reflectance at different times;
Calculating the equivalent admittance of the film that matches the reflection coefficient;
Calculate the thickness and refractive index of the thin film by the equivalent admittance,
A thin film monitoring method comprising the above steps.   2. The thin film monitoring method according to claim 1, wherein the pixelated phase mask image detection unit includes a photodetector including a birefringent crystal array aligned with a pixel array to which a polarizing plate is coupled. Monitoring method.   2. The thin film monitoring method according to claim 1, wherein the pixelated phase mask image detection unit includes a photodetector including a polarizing plate array aligned with a pixel array to which a quarter wave plate is coupled. A thin film monitoring method.   2. The thin film monitoring method according to claim 1, wherein the step of generating the interference light in the dynamic interferometer to obtain a reflection phase corresponding to the interference intensity is received by the pixelated phase mask image detection unit. A thin film monitoring method, characterized in that: a different phase shift interferogram is generated, and then the dynamic interferometer obtains the reflected phase by the phase shift interferogram.   2. The thin film monitoring method according to claim 1, wherein a coherence length of the low coherence light is larger than a total optical thickness of the thin film and smaller than an optical thickness of the substrate.   2. The thin film monitoring method according to claim 1, wherein the step of causing the dynamic interferometer to generate the interference light and obtaining a reflection phase corresponding to the interference intensity matches the interference light by using a phase shift algorithm. A thin film monitoring method, characterized in that it is provided for obtaining a reflection phase.   2. The thin film monitoring method according to claim 1, wherein in the step of causing the dynamic interferometer to generate the interference light and obtaining a reflection phase corresponding to interference intensity, the dynamic interferometer includes the pixelated phase mask image detection unit. A method of monitoring a thin film, comprising: detecting the interference light through the thin film.   8. The thin film monitoring method according to claim 7, wherein the image detection result of the pixelated phase mask image detection unit includes a plurality of pixels, and four pixels are set as one unit, and each unit is recorded as a phase. A thin film monitoring method.   2. The thin film monitoring method according to claim 1, wherein the reflected first linearly polarized light passing through the substrate and the reflected second linearly polarized light form a plurality of reflected light beams, and the two light beams of each pair interfere with each other. A method for monitoring a thin film, wherein a path difference between a pair of reflected light beams is smaller than a coherence length when a path length difference between two mirrors to a polarizing beam splitter is equal to an optical thickness of a substrate.   11. The thin film monitoring method according to claim 10, wherein each pair of light beams interferes with each other after passing through the polarizing plate.   11. A thin film monitoring method according to claim 10, wherein a reference reflective surface is inserted on the substrate, the path difference is made equal to the distance between the reference surface and the back surface of the substrate, and the surface has a reflection phase and a thin film formation change. A thin film monitoring method, characterized in that the contour is measured and monitored by the interference of all pairs of light fluxes.   2. The thin film monitoring method according to claim 1, wherein a thin film coefficient at each time is recorded to form a trajectory of a thin film formation change in order to obtain a monitoring chart of a thin film reflection coefficient.   2. The thin film monitoring method according to claim 1, wherein the equivalent admittance at each time is recorded in order to form a trajectory of a thin film formation change in order to obtain a monitoring chart of an equivalent admittance of the thin film.   15. The thin film monitoring method according to claim 14, wherein in the step of adding the monitoring sensitivity at the growth end point on the left side of the locus, a phase shift of pi is added on the reflection phase, and the corresponding optical admittance is recalculated to monitor the monitoring sensitivity. A thin film monitoring method characterized by the above.

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