CN116659398A - Wafer surface shape measurement system and measurement method based on wafer surface shape measurement system - Google Patents
Wafer surface shape measurement system and measurement method based on wafer surface shape measurement system Download PDFInfo
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- G—PHYSICS
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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
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Abstract
The disclosure provides a wafer surface shape measurement system and a measurement method based on the wafer surface shape measurement system, which relate to the technical field of semiconductor measurement and comprise the following steps: the sweep frequency laser output module outputs a first light beam with set frequency to the light path module; the optical path module is used for processing the first light beam and emitting the generated second light beam to the surface of the wafer to be tested; the photoelectric detection module is used for collecting interference light and generating an analog electric signal; and the data processing module is used for acquiring the analog electric signal based on the set frequency, converting the analog electric signal into a digital signal and calculating and determining the thickness information of the wafer. The first light beam with the set frequency is output through the sweep laser, then the analog electric signal is acquired based on the set frequency, conversion from the wavelength space to the wave number space can be realized in hardware, and compared with the wafer surface shape measurement system and method in the prior art, the wafer surface shape measurement method can realize the measurement of the wafer surface shape through single-path interference light, and is simpler, less in requirement on hardware and low in measurement cost.
Description
Technical Field
The disclosure relates to the technical field of semiconductor measurement, in particular to a wafer surface shape measurement system and a measurement method of the wafer surface shape measurement system.
Background
Wafer (silicon wafer) flatness is an important surface parameter index of a wafer, and represents the thickness spatial variation of the wafer, so that the surface shape (thickness curve) of the wafer can reflect the flatness of the wafer. With the continuous development of ultra-large scale integrated circuits, the characteristic line width of the integrated circuits is smaller and smaller, the integration level is higher and higher, and the flatness of the wafer is required to ensure the optical focusing of photoetching.
In the prior art, a gold source is measured through a wafer surface shape real-time on-line measurement system, and the gold source comprises an optical path structure, a sweep frequency laser and a data acquisition and operation device, wherein the data acquisition and operation device comprises a photoelectric detector, a high-frequency acquisition card, a PC, a PLC and a photoelectric encoder; the sweep laser outputs light beams to the light path structure, the light path structure carries out branching processing on the light beams to generate measurement interference light MUR and measurement interference light MLR, the photoelectric detector carries out photoelectric conversion on the detected measurement interference light MUR and measurement interference light ML R to generate corresponding photoelectric signals, the high-frequency acquisition card carries out data acquisition on photoelectric signals and transmits the data to the PC, the PC carries out processing on the acquired signals to obtain wafer thickness information, the photoelectric encoder transmits motion parameters of wafer processing equipment to the PLC to carry out acquisition, and then transmits the motion parameters to the PC, and the PC carries out calculation processing to obtain wafer surface profile. The method needs to use the reference arm and the measuring arm, has complex structure, high adjustment difficulty, more slides, low fault tolerance and high cost.
Disclosure of Invention
The present disclosure aims to solve, at least to some extent, one of the technical problems in the related art.
To this end, it is an object of the present disclosure to propose a wafer profile measurement system.
A second object of the present disclosure is to provide a wafer profile measurement method.
To achieve the above object, embodiments of a first aspect of the present disclosure provide a wafer surface shape measurement system, including: the sweep frequency laser output module is used for outputting a first light beam with set frequency to the light path module; the optical path module is used for processing the first light beam to generate a second light beam and emitting the second light beam to the wafer surface to be tested, and the second light beam acts on the upper surface and the lower surface of the wafer surface to be tested respectively to form corresponding first reflected light and second reflected light; the photoelectric detection module is used for collecting interference light and generating an analog electric signal based on the interference light, wherein the interference light is formed by interaction of first reflected light and second reflected light; the data processing module is used for acquiring an analog electric signal based on a set frequency, converting the analog electric signal into a digital signal, and determining wafer thickness information of the wafer surface to be tested based on the digital signal and an original spectrum of the first light beam.
According to one embodiment of the present disclosure, an optical path module includes: the device comprises a plano-convex lens, a beam splitter, a light shield and a window sheet; the sweep laser output module is used for enabling the first light beam to be incident on the beam splitter, forming transmitted light and reflected light based on the beam splitter, enabling the transmitted light to be incident on the light shield, enabling the reflected light to be incident on the window sheet, and enabling the reflected light to be vertically incident on the wafer surface to be tested through the window sheet; the interference light is incident on the receiving surface of the photoelectric detection module through the plano-convex lens.
According to one embodiment of the present disclosure, a data processing module includes: an OCT data acquisition card and a processor; the OCT data acquisition card is used for acquiring photoelectric signals and converting the photoelectric signals into digital signals; and the processor is used for receiving the data signals and determining the wafer thickness information of the wafer surface to be tested based on the digital signals.
According to one embodiment of the present disclosure, determining wafer thickness information for a wafer surface to be measured based on an original spectrum of a first beam and a photoelectric signal includes: performing signal analysis on the photoelectric signal based on the original spectrum to obtain a target interference spectrum; and determining a spectrum peak value based on the target interference spectrum, and determining wafer thickness information of the wafer surface to be detected based on the spectrum peak value.
According to one embodiment of the present disclosure, determining wafer thickness information for a wafer surface to be measured based on spectral peaks includes: acquiring an average group refractive index of a wafer surface to be measured in a light source wave band range; and dividing the spectrum peak value by twice the average group refractive index to obtain the wafer thickness information.
According to one embodiment of the present disclosure, signal analysis of an optical electrical signal to obtain a target interference spectrum includes: signal segmentation is carried out on the photoelectric signal according to a segmentation period to obtain segmentation data, wherein the segmentation period is the reciprocal of a set frequency; sampling the divided data at equal intervals in a wave number space to obtain space conversion data; d, DC is removed from the space conversion data based on the original spectrum so as to obtain candidate interference spectrums; performing spectrum shaping on the candidate interference spectrum to obtain a target interference spectrum; and carrying out Fourier transform on the target interference spectrum to obtain the target interference spectrum.
According to one embodiment of the present disclosure, the system further comprises: a displacement module and a drive controller; the displacement module is provided with a fixing piece which is used for fixing the wafer surface to be tested; the driving controller is used for controlling the movement of the displacement module and sending the position information of the displacement module to the processor.
According to one embodiment of the present disclosure, a processor determines surface type information of a wafer surface to be measured based on the position information and the wafer thickness information.
According to one embodiment of the present disclosure, a swept laser output module outputs a first beam to an optical path module through a single mode fiber.
To achieve the above object, an embodiment of a second aspect of the present disclosure provides a measurement method of a wafer surface shape measurement system, including: outputting a first light beam with set frequency to the light path module through the sweep laser output module; processing the first light beam through the light path module to generate a second light beam, and emitting the second light beam to the surface of the wafer to be tested, wherein the second light beam acts on the upper surface and the lower surface of the wafer to be tested respectively to form corresponding first reflected light and second reflected light; collecting interference light through a photoelectric detection module and generating an analog electric signal based on the interference light, wherein the interference light is formed by interaction of first reflected light and second reflected light; the method comprises the steps of collecting analog electric signals through a data processing module, converting the analog electric signals into digital signals, and determining wafer thickness information of a wafer surface to be detected based on the digital signals and an original spectrum of a first light beam.
To achieve the above-described embodiments, the embodiments of the present disclosure also propose a non-transitory computer readable storage medium storing computer instructions for causing a computer to implement a measurement method based on a wafer profile measurement system as the embodiments of the second aspect of the present disclosure.
To achieve the above embodiments, the embodiments of the present disclosure also propose a computer program product comprising a computer program which, when executed by a processor, implements a measurement method based on a wafer profile measurement system as the embodiments of the second aspect of the present disclosure.
The first light beam with the set frequency is output through the sweep laser, then the analog electric signal is acquired based on the set frequency, conversion from the wavelength space to the wave number space can be realized in hardware, and compared with the wafer surface shape measurement system and method in the prior art, the wafer surface shape measurement method can realize the measurement of the wafer surface shape through single-path interference light, and is simpler, less in requirement on hardware and low in measurement cost.
Drawings
FIG. 1 is a schematic block diagram of a wafer profile measurement system of one embodiment of the present disclosure;
FIG. 2 is a schematic diagram of the generation of interference light by a wafer profile measurement system according to one embodiment of the present disclosure;
FIG. 3 is a schematic view of the optical path module of a wafer profile measurement system according to one embodiment of the present disclosure;
FIG. 4 is a schematic diagram illustrating a step of determining wafer thickness information of a wafer surface to be measured based on an original spectrum of a first light beam and a photoelectric signal of a wafer surface shape measurement system according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of a target interference spectrum of a wafer profile measurement system according to one embodiment of the present disclosure;
FIG. 6 is a schematic diagram illustrating a step of determining wafer thickness information of a wafer surface to be measured based on spectral peaks in a wafer surface shape measurement system according to an embodiment of the present disclosure;
FIG. 7 is a schematic diagram of a wafer profile measurement system for generating profile information for a zig-zag scan in accordance with one embodiment of the present disclosure;
fig. 8 is a flow chart of a measurement method based on the wafer surface shape measurement system of the present disclosure.
Detailed Description
Embodiments of the present disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and intended for the purpose of explaining the present disclosure and are not to be construed as limiting the present disclosure.
Fig. 1 is a schematic structural diagram of a wafer surface shape measurement system according to the present disclosure, as shown in fig. 1, the wafer surface shape measurement system 100 includes: the device comprises a sweep laser output module 110, an optical path module 120, a photoelectric detection module 130 and a data processing module 140.
The swept laser output module 110 is configured to output a first light beam with a set frequency to the optical path module 120. The swept laser output module 110 in the embodiments of the present disclosure may be a swept laser, where the first beam setting frequency of the swept laser module is set in advance, and may be changed according to actual design requirements, which is not limited in any way.
The optical path module 120 is configured to process the first light beam to generate a second light beam, and emit the second light beam to the surface of the wafer to be tested, where the second light beam acts on the upper surface and the lower surface of the wafer to be tested to form a first reflected light and a second reflected light respectively.
In the embodiment of the present disclosure, the process of generating the interference light is shown in fig. 2, and it should be noted that, for convenience of illustration, the first reflected light and the second reflected light are not drawn on the same straight line, and in fact, are light beams on the same straight line. The second light beam is incident on the wafer surface to be measured, a part of light is reflected by the upper surface of the wafer surface to be measured, and a part of light is reflected by the lower surface of the wafer surface to be measured.
It should be noted that, the wafer surfaces to be measured with different thicknesses have different overlapping positions of the two reflected lights, so that the interference lights formed finally can be different, and the thickness of the current wafer surface to be measured at the detection position can be determined by analyzing the interference lights. Compared with the prior art that the interference light MUR and the interference light MLR are measured in a matched mode, the reference light path is omitted, and the measuring method is simpler.
It should be noted that, as shown in fig. 3, the optical path module 120 in the embodiment of the disclosure may include a plano-convex lens, a beam splitter, a light shielding cover, and a window sheet. Compared with the optical path structure in the prior art, the optical path module 120 in the present disclosure has a simple structure, uses fewer slides, and can reduce the influence of the slides on the whole wafer surface shape measurement process.
The sweep laser output module 110 makes the first beam incident on the beam splitter, forms transmitted light and reflected light based on the beam splitter, makes the transmitted light incident on the light shield, makes the reflected light incident on the window plate, and makes the reflected light vertically incident on the wafer surface to be tested through the window plate.
The photoelectric detection module 130 is configured to collect interference light and generate an analog electrical signal based on the interference light, where the interference light is formed by interaction of the first reflected light and the second reflected light. In an embodiment of the present disclosure, the photo-detection module 130 may be a photo-detector.
In this embodiment, the interference light is incident on the receiving surface of the photodetection module 130 through the plano-convex lens, so that the photodetection module 130 can collect the interference light. It should be noted that, the interference light collected by the photo-detecting module 130 may be continuous or may be collected periodically, and the period may be set in advance and may be changed according to the actual design requirement, which is not limited in any way.
The data processing module 140 is configured to collect an analog electrical signal based on a set frequency, convert the analog electrical signal into a digital signal, and determine wafer thickness information of the wafer surface to be measured based on the digital signal and an original spectrum of the first light beam.
In an embodiment of the present disclosure, the data processing module 140 includes an optical coherence tomography OCT data acquisition card and a processor.
The OCT data acquisition card is used for acquiring photoelectric signals and converting the photoelectric signals into digital signals. The optical source outputs with k clocks, the OCT data acquisition card with k clocks uniformly sampled is used, the conversion from wavelength space to wave number space can be realized on hardware, and the thickness information can be obtained through one-time Fourier transformation by hardware configuration and algorithm reduction steps.
And the processor is used for receiving the data signals and determining the wafer thickness information of the wafer surface to be tested based on the digital signals. It should be noted that the processor may include various types, for example, a computer, an industrial personal computer, etc.
In the embodiment of the disclosure, the determining the wafer thickness information of the wafer surface to be measured based on the photoelectric signal and the original spectrum of the first light beam may further be explained by fig. 4, which includes:
s401, performing signal analysis on the photoelectric signal based on the original spectrum to acquire a target interference spectrum.
In the embodiment of the disclosure, firstly, a signal is split according to a splitting period to obtain splitting data, the splitting period is the inverse of a set frequency, then, wave number space equidistant sampling is performed on the splitting data to obtain space conversion data, then, direct current is removed from the space conversion data based on an original spectrum to obtain candidate interference spectrums, then, spectrum shaping is performed on the candidate interference spectrums to obtain target interference spectrums, and finally, fourier transformation is performed on the target interference spectrums to obtain the target interference spectrums.
In the embodiment of the disclosure, when the photoelectric signal is divided according to the dividing period, the frequency of f is continuously scanned by the sweep frequency light source, namely 1/f is a complete wavelength scanning period, so that the signal needs to be divided first, and the process is completed by continuously triggering and sampling the digital acquisition card through synchronizing the clock signal of the scanning frequency f of the single period of the input light source to the digital acquisition card, the triggering signal of the sweep frequency period of the light source and the interference signal acquired by the photoelectric detector.
In the case of spatial conversion, since the subsequent signal processing involves FourierThe leaf transform, while the nature of the fourier transform requires that the signal be uniformly sampled, i.e. where wavenumber space equidistant sampling of the interference signal is required. The wave number does not change linearly with time in the sweep process of the light source, so the conversion from the wavelength space to the wave number space is completed by the digital acquisition card. In addition, since the FFT is 2 in signal length n The time efficiency is highest, so in the sampling setting of the digital acquisition card, the sampling point number of each period needs to be set to be 2 n 。
When the DC removing step is performed, the principle resolving process proves that the finally needed resolving is the AC information in the interference signal, and the envelope signal introduced by the original spectrum, namely the DC signal in the interference signal, can cause interference in the Fourier transform process, so that the DC removing process is needed for the collected signal. The method comprises the specific operation that an original spectrum signal is collected in advance in the system debugging process and is stored in a database, and the original spectrum is subtracted from an interference signal which is actually collected, namely, a direct current component is subtracted.
When performing spectral shaping, for fourier transform, noise and side lobes in an original signal affect calculation accuracy and resolution, and a method of windowing an interference spectrum signal is generally adopted to reduce spectrum energy leakage and suppress interference caused by the side lobes. For example, a Gahanning window may be employed for spectral shaping to obtain a target interference spectrum.
After the target interference spectrum is obtained, a Fast Fourier Transform (FFT) algorithm may be used to implement fourier transform of the discrete signal, thereby implementing conversion of the target interference spectrum into the target interference spectrum.
S402, determining a spectrum peak value based on the target interference spectrum, and determining wafer thickness information of the wafer surface to be tested based on the spectrum peak value.
In one possible implementation example, assume that the original spectrum of the light source is P 0 (k) Where k is the wave number, which varies with time. The wafer thickness value is D, and the optical path difference of the light reflected by the upper surface and the lower surface is L L nD, where n is the average group refractive index of the wafer (k) in the light source band range.
The expression of the interference spectrum is:
wherein P is 0 The term "k" is an interference spectrum, α is a spectral ratio, and β is a constant related to the spectral ratio, and it should be noted that the constants related to the spectral ratio and the spectral ratio are different depending on the wafer surface to be measured, and are not limited in any way.
After fourier transformation is performed on the interference spectrum, a target interference spectrum can be obtained, and the expression is as follows:
S(l)＝FT{P 0 (k)}+β·FT{P 0 (k)}·FT{cos(2πk△L)}
＝FT{P 0 (k)}+β·FT{P 0 (k)}·【δ(l-△L)+δ(l+△L)】
as shown in fig. 5, when the spectrum peak reaches the maximum value, i.e., the wafer thickness at this time, l= Δl, the thickness information can be obtained by directly locating the side peak position.
Therefore, the interference spectrum is obtained by analyzing the interference spectrum, the side peak position is rapidly positioned, the thickness information of the current measurement point position is determined based on the side peak position, and the efficiency and the accuracy of obtaining the thickness information can be improved.
It should be noted that, for convenience in the following calculation, after fourier transformation, the spectrum coordinate conversion may be performed on the target interference spectrum. For example, assuming that the signal abscissa in the original signal is the wave number k, the k value ranges from k1 to k2, the sampling interval is δk, the sampling point number is N, the fourier domain abscissa of the ith sampling point isWherein the value range of i is 1-N-1, and the ordinate Y of the ith sampling point position i The definition may be based on the actual waveform.
In the embodiment of the present disclosure, determining the wafer thickness information of the wafer surface to be measured based on the spectral peak value may be further explained by fig. 6, which includes:
s601, obtaining the average group refractive index of the wafer surface to be tested in the light source wave band range.
In the embodiment of the disclosure, the average group refractive index corresponding to different wafer surfaces to be tested may be different, which is not limited herein.
Alternatively, the average group refractive index corresponding to the wafer surface to be tested can be obtained through experiments.
Alternatively, the average group refractive index relation table may be obtained by querying the average group refractive index relation table, which is set in advance or is an industry specification, and is not limited in any way.
S602, dividing the spectrum peak value by twice the average group refractive index to obtain the wafer thickness information.
In the embodiment of the disclosure, the wafer thickness information of the wafer surface to be measured may be calculated by the thickness coordinates, and may be calculated by the following formula:
△L peak to peak ＝2nY Peak to peak
Wherein DeltaL Peak to peak For the wafer thickness of the wafer surface to be measured, n is the average group refractive index of the wafer surface to be measured in the light source wave band range, Y Peak to peak Is the spectral peak.
In the embodiment of the disclosure, the average group refractive index of the wafer surfaces to be measured may be different, and is not limited herein, and the spectrum peak value Y is specifically set according to the actual situation Peak to peak Can be obtained by reading the target interference spectrum.
In an embodiment of the present disclosure, the wafer profile measurement system further includes a displacement module and a drive controller.
The displacement module is provided with a fixing piece which is used for fixing the wafer surface to be tested. It should be noted that the fixing member is used for fixing the wafer surface to be tested, and the fixing member may be various, for example, a fixing chuck, a fixing strap, etc. may be provided, and the fixing member is not limited herein, and may be specifically limited according to actual design requirements.
The driving controller is used for controlling the movement of the displacement module and sending the position information of the displacement module to the processor.
In the embodiment of the disclosure, after the processor obtains the position information and the wafer thickness information, the processor may determine the surface type information of the wafer surface to be measured based on the position information and the wafer thickness information.
It should be noted that, the displacement module may include a plurality of motion modes, for example, as shown in fig. 7, in one motion mode of the displacement table, taking a form of scanning in a shape of a Chinese character mi as an example, 9 points are measured at equal intervals on a diameter during scanning measurement, for example, pixel points marked as "T" in fig. 7, the four measuring diameter paths are uniformly distributed at equal angles, 10 thickness values measured in 10 sweep periods are averaged once to represent a single-point thickness, and the surface shape information of the wafer can be obtained in combination with the position information. Therefore, through multiple scanning and averaging, deviation of measurement results caused by experimental errors can be prevented, and accuracy of finally obtaining the thickness information of the wafer is improved.
Fig. 8 is a flow chart of a measurement method based on the wafer surface shape measurement system according to the above embodiment, as shown in fig. 8, and the method includes:
s801, outputting a first light beam with set frequency to an optical path module through a sweep laser output module.
S802, processing the first light beam through the light path module to generate a second light beam, and emitting the second light beam to the wafer surface to be tested, wherein the second light beam acts on the upper surface and the lower surface of the wafer surface to be tested respectively to form corresponding first reflected light and second reflected light.
S803, collecting interference light by the photodetection module, and generating an analog electrical signal based on the interference light, wherein the interference light is formed by interaction of the first reflected light and the second reflected light.
S804, acquiring an analog electric signal through a data processing module, converting the analog electric signal into a digital signal, and determining wafer thickness information of the wafer surface to be tested based on the digital signal and an original spectrum of the first light beam.
In the embodiment of the disclosure, the first light beam with the set frequency is output through the sweep laser, then the analog electric signal is acquired based on the set frequency, and the conversion from the wavelength space to the wave number space can be realized in hardware.
To achieve the above-described embodiments, the embodiments of the present disclosure also propose a non-transitory computer readable storage medium storing computer instructions for causing a computer to implement a measurement method based on a wafer profile measurement system as the embodiments of the second aspect of the present disclosure.
To achieve the above embodiments, the embodiments of the present disclosure also propose a computer program product comprising a computer program which, when executed by a processor, implements a measurement method based on a wafer profile measurement system as the embodiments of the second aspect of the present disclosure.
In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present disclosure.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present disclosure, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Although embodiments of the present disclosure have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the present disclosure, and that variations, modifications, alternatives, and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the present disclosure.
Claims (10)
1. A wafer profile measurement system, comprising: the device comprises an optical path module, a sweep laser output module, a photoelectric detection module and a data processing module, wherein the wafer surface to be tested is positioned under the optical path module,
the sweep frequency laser output module is used for outputting a first light beam with set frequency to the light path module;
the optical path module is used for processing the first light beam to generate a second light beam, and emitting the second light beam to the wafer surface to be tested, wherein the second light beam acts on the upper surface and the lower surface of the wafer surface to be tested respectively to form corresponding first reflected light and second reflected light;
the photoelectric detection module is used for collecting interference light and generating an analog electric signal based on the interference light, wherein the interference light is formed by interaction of the first reflected light and the second reflected light;
the data processing module is used for acquiring the analog electric signal based on the set frequency, converting the analog electric signal into a digital signal, and determining the wafer thickness information of the wafer surface to be detected based on the digital signal and the original spectrum of the first light beam.
2. The wafer profile measurement system of claim 1, wherein the optical path module comprises:
the device comprises a plano-convex lens, a beam splitter, a light shield and a window sheet;
the sweep laser output module is used for enabling the first light beam to be incident on the beam splitter, forming transmission light and reflection light based on the beam splitter, enabling the transmission light to be incident on the light shield, enabling the reflection light to be incident on the window sheet, and enabling the reflection light to be vertically incident on the wafer surface to be tested through the window sheet;
the interference light is incident on the receiving surface of the photoelectric detection module through the plano-convex lens.
3. The wafer profile measurement system of claim 1 or 2, wherein the data processing module comprises: an OCT data acquisition card and a processor; wherein,,
the OCT data acquisition card is used for acquiring the photoelectric signals based on a set frequency and converting the photoelectric signals into digital signals;
the processor is used for receiving the data signals and determining the wafer thickness information of the wafer surface to be tested based on the digital signals.
4. The wafer surface shape measurement system of claim 3, wherein said determining wafer thickness information for the wafer surface to be measured based on the photoelectric signal and the raw spectrum of the first beam of light comprises:
performing signal analysis on the photoelectric signal based on the original spectrum to acquire a target interference spectrum;
and determining a spectrum peak value based on the target interference spectrum, and determining the wafer thickness information of the wafer surface to be detected based on the spectrum peak value.
5. The wafer profile measurement system of claim 4, wherein said determining wafer thickness information for the wafer profile to be measured based on the spectral peak value comprises:
acquiring the average group refractive index of the wafer surface to be measured in the light source wave band range;
and dividing the spectrum peak value by twice the average group refractive index to obtain the wafer thickness information.
6. The wafer profile measurement system of claim 4, wherein said signal analyzing the optoelectronic signal to obtain a target interference spectrum comprises:
performing signal segmentation on the photoelectric signal according to a segmentation period to obtain segmentation data, wherein the segmentation period is the reciprocal of the set frequency;
sampling the divided data at equal intervals in a wave number space to obtain space conversion data;
DC is removed from the space conversion data based on the original spectrum so as to obtain candidate interference spectrums;
performing spectrum shaping on the candidate interference spectrum to obtain a target interference spectrum;
and carrying out Fourier transform on the target interference spectrum to obtain the target interference spectrum.
7. The wafer profile measurement system of claim 4, wherein the system further comprises:
a displacement module and a drive controller;
the displacement module is provided with a fixing piece which is used for fixing the wafer surface to be tested;
the driving controller is used for controlling the movement of the displacement module and sending the position information of the displacement module to the processor.
8. The wafer surface shape measurement system of claim 7, wherein the processor determines the surface shape information of the wafer surface to be measured based on the position information and the wafer thickness information.
9. The wafer profile measurement system of claim 1, wherein the swept laser output module outputs the first beam to the optical path module via a single mode fiber.
10. A measurement method based on the wafer profile measurement system as claimed in claims 1-9, comprising:
outputting a first light beam with set frequency to the light path module through the sweep laser output module;
processing the first light beam through the light path module to generate a second light beam, and emitting the second light beam to the wafer surface to be tested, wherein the second light beam acts on the upper surface and the lower surface of the wafer surface to be tested respectively to form corresponding first reflected light and second reflected light;
collecting interference light by the photoelectric detection module and generating an analog electric signal based on the interference light, wherein the interference light is formed by interaction of the first reflected light and the second reflected light;
and acquiring the analog electric signal through the data processing module, converting the analog electric signal into a digital signal, and determining the wafer thickness information of the wafer surface to be detected based on the digital signal and the original spectrum of the first light beam.
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