Optical film layer manufacturing method, optical filter, and spectrometer

Abstract

The embodiment of the application belongs to the field of micro-nano photoelectric devices, and particularly relates to an optical film layer manufacturing method, an optical filter and a spectrometer. The embodiment of the application aims to solve the problems of low yield and poor wavelength expansion of the optical filter in the related art. The optical film layer manufacturing method of the embodiment of the application comprises the following steps: providing a substrate, wherein the substrate comprises a detector array for photoelectric detection, and the detector array comprises an incident light side; placing the substrate in a vacuum chamber, so that the incident light side faces a film layer material source and is vertically arranged, and the incident light side is located in a film layer material plume formed by the film layer material source, so as to form an optical film layer with a thickness gradually decreasing from bottom to top on the incident light side. The optical film layer manufacturing method provided by the embodiment of the application can improve the yield and wavelength expansion of the optical filter.

Description

Technical Field

[0001] This application belongs to the field of micro-nano optoelectronic device technology, and particularly relates to an optical film fabrication method, a filter, and a spectrometer. Background Technology

[0002] Spectrometers play a vital role in materials characterization, industrial testing, and environmental monitoring. A typical spectrometer consists of a substrate, a detector array mounted on the substrate, and a filter located on the side of the detector array facing away from the substrate. The filter has a filtering layer whose thickness gradually increases along a direction parallel to the incident light side of the detector.

[0003] In related technologies, the filter is usually fabricated using chemical mechanical polishing (CMP) or gray-scale lithography combined with reactive ion etching (GSL-RIE).

[0004] However, the filters produced by the above method have a low yield and poor band scalability. Summary of the Invention

[0005] In view of this, embodiments of this application provide an optical film fabrication method, a filter, and a spectrometer to solve the technical problems of low filter yield and poor band scalability of filters produced in related technologies.

[0006] This application provides a method for fabricating an optical film, applied to a vacuum vapor deposition apparatus. The vacuum vapor deposition apparatus includes a vacuum chamber, in which a film material source is disposed, and the normal of the film material source is vertically upward. The manufacturing method includes: A substrate is provided, the substrate including a detector array for photoelectric detection, the detector array including an incident light side; The substrate is placed in the vacuum chamber such that the light incident side faces the film material source and is vertically arranged, and the light incident side is located within the film material plume formed by the film material source, so as to form an optical film layer with a thickness that gradually decreases from bottom to top on the light incident side.

[0007] The optical film fabrication method of this application embodiment employs a vacuum phase deposition apparatus equipped with a film material source, wherein the normal of the film material source is vertically upward; the light incident side of the detector array in the substrate is oriented toward the film material source, and the light incident side is located within the bottom-up film material plume formed by the film material source; by utilizing an oblique incident projection mechanism, an optical film with a thickness gradually decreasing from bottom to top is formed on the light incident side.

[0008] Compared with the CMP and GSL-RIE methods in related technologies, the optical film fabrication method of this application does not require a subtractive process, which can avoid the phenomenon of edge over-polishing; and it adopts pure physical vapor deposition, which has fewer influencing factors on the formation of optical film, which is conducive to precise control of the thickness of optical film, and is conducive to improving the thickness accuracy of optical film and wafer-level large area consistency.

[0009] Furthermore, the optical film fabrication method of this application embodiment utilizes the high versatility of physical vapor deposition. By simply changing the film deposition material or adjusting the deposition angle, optical films for different wavebands can be formed on the same substrate, quickly achieving cross-waveband customization and greatly improving production flexibility.

[0010] In some possible embodiments, the angle between the normal of the light-incident side and the normal of the film material source is greater than or equal to 70° and less than or equal to 90°.

[0011] In some possible embodiments, the vacuum phase deposition apparatus is an electron beam evaporation deposition apparatus, and the film material source is an evaporation source.

[0012] In some possible embodiments, the vacuum level of the vacuum chamber is 1 × 10^ -7 Torr ~ 1×10^ -5 Torr; a substrate is disposed within the vacuum chamber, and the evaporation source is disposed on the substrate; the temperature of the substrate is 40℃~80℃; the evaporation rate of the evaporation source is 0.1 Å / s~0.5 Å / s; the horizontal distance between the evaporation source and the incident light side is 30cm~50cm; the evaporation time of the evaporation source is 100s~1000s.

[0013] In some possible embodiments, the material evaporated by the evaporation source includes at least one of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

[0014] In some possible embodiments, the vacuum phase deposition equipment is a magnetron sputtering deposition equipment, and the film material source is a target material.

[0015] In some possible embodiments, before placing the substrate inside the vacuum chamber, a passivation layer is formed on the light-incident side.

[0016] In some possible embodiments, the detector array is a CMOS array.

[0017] This application also provides a filter, which includes a filter layer, and the filter layer is prepared by any of the optical film fabrication methods described above.

[0018] The filter in this application embodiment includes a filter layer prepared by the above-described optical film preparation method. The filter has high thickness accuracy and large area consistency at the wafer level. This will not be described in detail in this application embodiment.

[0019] This application also provides a spectrometer including the above-described filter.

[0020] The spectrometer of this application embodiment includes the above-described filter, and therefore also has the advantages of the above-described filter, which will not be repeated here. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. It is obvious that the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the spectrometer according to an embodiment of this application; Figure 2 for Figure 1 A cross-sectional structural diagram of a filter in some possible implementations; Figure 3 for Figure 1 A cross-sectional view of the filter in some other possible implementations; Figure 4 for Figure 1 A cross-sectional view of the filter in some other possible implementations; Figure 5 for Figure 1 A cross-sectional view of the filter in some other possible implementations; Figure 6 This is a schematic flowchart of the optical film fabrication method according to an embodiment of this application; Figure 7 This is a schematic diagram showing the substrate placed inside a vacuum chamber. Figure 8 This is a schematic diagram of forming an optical film layer on a substrate; Figure 9This is a schematic diagram illustrating the principle of the optical film fabrication method according to an embodiment of this application.

[0023] Explanation of reference numerals in the attached figures: 100-substrate; 110 - Detector array; 111 - Incident light side; 200-filter; 210 - Filter layer; 220 - Optical dielectric layer; 300-Electron beam evaporation source. Detailed Implementation

[0024] Among related technologies, spectrometers based on computer reconstruction algorithms have attracted widespread attention due to their advantages such as miniaturization and integrability. Such a spectrometer may include a detector array and a filter located on the incident light side of the detector array. The thickness of the filter gradually increases along the direction parallel to the incident light side. Based on the Fabry-Perot principle, when light is incident on the filter, different thickness regions of the filter can select different wavelengths, thereby enabling the detector array to receive incident light of different wavelengths and thus obtain the spectral information of the detected object.

[0025] In some related technologies, the above-mentioned filter is usually manufactured using a subtractive process. This involves first providing a pre-defined optical film layer with two parallel surfaces. In other words, the thickness of the pre-defined optical film layer is uniform throughout. Then, the film material on one of the surfaces of the pre-defined optical film layer is removed to form the aforementioned filter.

[0026] In some possible implementations, chemical mechanical polishing (CMP) can be used to remove the film material from one of the surfaces of the pre-designed optical film. However, when using CMP to fabricate the above-mentioned filter, due to the deformation of the polishing pad, uneven distribution of polishing stress, and the macroscopic characteristics of the polishing fluid's hydrodynamics, the edge polishing amount of the polished surface is easily excessive, i.e., over-polishing of the edges occurs. This is not conducive to global planarization of the polished surface, thereby reducing the dimensional accuracy of the fabricated filter.

[0027] In other possible implementations, grayscale lithography combined with reactive ion etching (GSL-RIE) can be used to remove the film material on one surface of the pre-defined optical film. However, when fabricating the aforementioned filter using the GSL-RIE method, the etching rate of the film material undergoes a nonlinear spatial shift due to factors such as the micro-loading effect of reactive ion etching and the non-uniformity of plasma distribution. Furthermore, during the etching of the pre-defined optical film, reactive ions inevitably introduce physical damage and nanoscale roughness into the surface of the pre-defined optical film, increasing optical scattering loss.

[0028] Both of these manufacturing methods make it difficult to precisely control the thickness of the produced filters. For spectrometers equipped with filters from different production batches, this reduces the consistency of their spectral response matrix, thereby lowering the mass production yield of the spectrometer.

[0029] Furthermore, both of the above fabrication methods suffer from poor band scalability. Specifically, the technical parameters of the CMP and GSL-RIE methods are highly dependent on the physicochemical properties of the pre-designed optical film materials. When the application of the spectrometer expands to the ultraviolet or mid-to-far-infrared bands, the pre-designed optical film materials need to be changed, for example, replacing silicon with titanium dioxide, germanium, or fluorides. The original technical parameters cannot be directly used and must be redesigned for the changed pre-designed optical film materials. For example, the polishing slurry (containing specific abrasive particles and chemical etchants) or etching system (including etching gas composition, RF power, and chamber pressure) needs to be reconfigured. This significantly extends the development cycle and increases the development cost of the band-extended spectrometer.

[0030] In summary, how to improve the mass production yield of this filter and how to improve its band scalability have long been technical problems that need to be solved by those skilled in the art.

[0031] To address the aforementioned technical problems, this application provides an optical film fabrication method, a filter, and a spectrometer, proposing a "bottom-up" additive manufacturing approach. The optical film fabrication method of this application employs a vacuum vapor deposition apparatus equipped with a film material source, the normal of which is vertically upward. The light-incident side of the detector array in the substrate is oriented towards the film material source, and the light-incident side is positioned within the bottom-up plume of film material formed by the source. Utilizing an oblique incident projection mechanism, an optical film with a thickness gradually decreasing from bottom to top is formed on the light-incident side.

[0032] Compared with the CMP and GSL-RIE methods in related technologies, the optical film fabrication method of this application does not require a subtractive process, which can avoid the phenomenon of edge over-polishing; and it adopts pure physical vapor deposition, which has fewer influencing factors on the formation of optical film, which is conducive to precise control of the thickness of optical film, and is conducive to improving the thickness accuracy of optical film and wafer-level large area consistency.

[0033] Furthermore, the optical film fabrication method of this application embodiment utilizes the high versatility of physical vapor deposition. By simply changing the film deposition material or adjusting the deposition angle, optical films for different wavebands can be formed on the same substrate, quickly achieving cross-waveband customization and greatly improving production flexibility.

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] like Figure 1 As shown, the spectrometer in this embodiment may include a substrate 100. The substrate 100 may be provided with a detector array 110, which can be used for photoelectric detection. The detector array 110 may have an incident light side 111. When performing spectral detection on an object, the light emitted by the object enters the detector array 110 from the incident light side 111. The detector array 110 converts the optical information into electrical information, thereby obtaining the spectrum of the object under test. Exemplarily, the detector array 110 may be a complementary metal-oxide-semiconductor (CMOS) array. CMOS arrays have advantages such as low power consumption, high speed, strong anti-interference capability, high integration, good compatibility, low driving requirements, and good signal isolation. Furthermore, the manufacturing process of CMOS arrays is mature, and the devices have good stability, which helps to reduce the production cost of the spectrometer and improve the performance stability of the spectrometer.

[0036] In some possible implementations of the embodiments of this application, the detector array 110 can also be a charge-coupled device (CCD) array. CCD arrays have advantages such as high resolution and high noise immunity, which are beneficial to improving the spectral detection accuracy of the spectrometer.

[0037] The spectrometer in this embodiment may further include a filter 200, which is used to select light of a specific wavelength so that the light of that specific wavelength enters a specific pixel of the detector array 110. The filter 200 may include a filter layer 210. Along a direction parallel to the light incident side 111 of the detector, for example... Figure 1 As shown in the horizontal direction x, the thickness of the filter layer 210 can gradually increase. Based on the Fabry-Perot principle, when light is incident on the filter layer 210, different thickness regions of the filter layer 210 can select different wavelengths, thereby enabling different pixels of the detector array 110 to receive incident light of different wavelengths, and thus obtain the spectral information of the detected object.

[0038] In some possible implementations of the embodiments of this application, reference is made to Figure 2 The filter 200 may consist of only the filter layer 210. This simplifies the structure of the filter 200 and reduces its manufacturing difficulty and cost. For example, the filter layer 210 may be made of an insulating material. For instance, the insulating material may include at least one of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

[0039] In other possible implementations of this application, the filter 200 may further include at least one optical medium layer 220, which may be disposed on at least one side of the filter layer 210. By providing the optical medium layer 220, the filter 200 can form a multilayer composite film system, which is beneficial to improving the filtering accuracy of the filter 200.

[0040] For example, the number of optical medium layers 220 can be one, two or more, which will not be elaborated further in the embodiments of this application.

[0041] For example, the optical dielectric layer 220 may be disposed on the side of the filter layer 210 facing away from the detector array 110; for example Figure 3 As shown, the optical dielectric layer 220 can be disposed on the upper side of the filter layer 210. The optical dielectric layer 220 can also be disposed on the side of the filter layer 210 facing the detector array 110; as shown... Figure 4 As shown, the optical dielectric layer 220 can also be disposed on the underside of the filter layer 210. The optical dielectric layer 220 can also be disposed on both sides of the filter layer 210, for example... Figure 5 As shown, the optical medium layer 220 can be disposed on the upper and lower sides of the filter layer 210.

[0042] This application also provides a method for fabricating an optical film. Exemplarily, the filter layer 210 of the filter 200 described above can be fabricated using this optical film fabrication method. The optical film fabrication method of this application embodiment will be specifically described below using a filter 200 comprising only the filter layer 210 as an example.

[0043] The optical film fabrication method of this application embodiment can be applied to a vacuum vapor deposition apparatus. The vacuum vapor deposition apparatus may include a vacuum chamber, and a film material source may be disposed within the vacuum chamber, with the normal of the film material source being vertically upward.

[0044] In some possible implementations of the embodiments of this application, the vacuum phase deposition equipment can be an electron beam evaporation vapor deposition equipment. The film material source can be an electron beam evaporation source 300. In other possible implementations of the embodiments of this application, the vacuum phase deposition equipment can also be a magnetron sputtering equipment. The film material source can be a target material.

[0045] The following uses an electron beam evaporation vapor deposition (EBV) apparatus as an example to specifically describe the optical film fabrication method of this application embodiment. When the VPV apparatus is a magnetron sputtering apparatus, the optical film fabrication method can be referred to the following description, which will not be repeated in this application embodiment.

[0046] refer to Figure 6 The optical film fabrication method of this application embodiment may include the following steps: S100. A substrate is provided, the substrate including a detector array for photoelectric detection, the detector array including an incident light side.

[0047] The description of the substrate 100 can be found above, and will not be repeated in this embodiment.

[0048] For example, when the detector array 110 in the substrate 100 is a CMOS array, the CMOS array can be fabricated using standard conventional CMOS processes.

[0049] In some possible implementations of the embodiments of this application, the optical film fabrication method of this application embodiment may further include: forming a passivation layer on the light-incident side 111. Exemplarily, the material of the passivation layer can be a transparent insulating material. The passivation layer can effectively ensure a high degree of consistency in the electrical performance and dark current level of the substrate 100.

[0050] S200. The substrate is placed in a vacuum chamber such that the light incident side faces the film material source and is vertically positioned, and the light incident side is located within the film material plume formed by the film material source, so as to form an optical film layer with a thickness that gradually decreases from bottom to top on the light incident side.

[0051] refer to Figure 7 The vacuum chamber can be the vacuum chamber of an electron beam evaporation vapor deposition (EBV) apparatus. The film material source can be an electron beam evaporation source 300. The electron beam evaporation source 300 can be located at the bottom of the vacuum chamber, and the normal S1 of the electron beam evaporation source 300 can be vertically aligned to form an evaporation plume from bottom to top, for example... Figure 7 As indicated by the dashed arrow. For example, the material evaporated by the evaporation source includes at least one of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

[0052] The substrate 100 is then placed within a vacuum chamber. Exemplarily, the vacuum chamber may have a vertically oriented inner wall, and the substrate 100 may be attached to the inner wall of the vacuum chamber. The light-incident side 111 of the substrate 100 may face the electron beam evaporation source 300. The light-incident side 111 may be located within a plume of film material formed by the electron beam evaporation source 300. Film material carried by the film material plume may be deposited on the light-incident side 111 to form a filter layer 210 with a thickness gradually decreasing from bottom to top on the light-incident side 111.

[0053] The optical film fabrication method of this application embodiment, due to the vertical arrangement of the light-incident side 111 of the substrate 100, and the spatial radiation geometric distribution law of the evaporation plume and the inverse square law of distance, and the natural attenuation mechanism of the film formation rate caused by the spatial distance difference and the distribution of the emission angle (cosnθ), utilizes the oblique incident projection mechanism to form a filter layer 210 with a thickness gradually decreasing from bottom to top on the light-incident side 111. For example... Figure 8 As shown.

[0054] Specifically, refer to Figure 9 Let the center of the electron beam evaporation source 300 be the origin O, and the normal direction S1 of the electron beam evaporation source 300 be the z-axis. Let α be the angle between the normal S2 of the incident light side 111 and the normal S1 of the electron beam evaporation source 300. Using an angle α of 90° as an example, the principle of the optical film fabrication method of this application embodiment will be explained.

[0055] Let D be the horizontal distance between the plane containing the incident light side 111 and the electron beam evaporation source 300, and let z be the height of any point P on the incident light side 111 relative to the electron beam evaporation source 300. Then the distance r from the electron beam evaporation source 300 to point P is...

[0056] The angular distribution of the membrane material plume can be approximated as follows:

[0057] Where θ is the angle between the line connecting OP and the normal S1 of the electron beam evaporation source 300, and m is the plume distribution index. Since And the projection factor of the incident direction relative to the normal S2 of the incident side 111 is Therefore, the deposition rate at point P can be approximated as:

[0058] Where K is a proportionality coefficient related to evaporation rate, material properties, and deposition efficiency. From this expression, it can be seen that the deposition rate...

[0059] The peak value is obtained at the point where the lower end height H of the incident light side 111 satisfies... At that time, the light-incident side 111 is entirely within the region where the deposition rate decreases with increasing height, thus enabling the formation of an optical film layer 210 with a thickness that gradually decreases from bottom to top on the light-incident side 111.

[0060] The optical film fabrication method of this application embodiment does not require complex process conditions and can fabricate optical films with continuously varying thicknesses without any dynamic masks or precision mechanical moving parts, thus solving the problem of difficulty in controlling large-area uniformity in subtractive processing.

[0061] Compared with the CMP and GSL-RIE methods in related technologies, the optical film fabrication method of this application does not require a subtractive process, which can avoid the phenomenon of edge over-polishing; and it adopts pure physical vapor deposition, which has fewer influencing factors on the formation of optical film, which is conducive to precise control of the thickness of optical film, and is conducive to improving the thickness accuracy of optical film and wafer-level large area consistency.

[0062] Furthermore, the optical film fabrication method of this application embodiment utilizes the high versatility of physical vapor deposition. By simply changing the film deposition material or adjusting the deposition angle, optical films for different wavebands can be formed on the same substrate, quickly achieving cross-waveband customization and greatly improving production flexibility.

[0063] In some possible implementations of the embodiments of this application, reference is made to Figure 7 The angle α between the normal S2 of the incident light side 111 and the normal S1 of the electron beam evaporation source 300 can be greater than or equal to 70° and less than or equal to 90°. This setting helps to prevent insufficient effective deposition flux due to an angle α that is too large or too small, thus preventing the formation of the desired film layer.

[0064] For example, the vacuum level of the vacuum chamber can be 1×10^ -7 Torr ~ 1×10^ -5Torr. A substrate can be placed inside the vacuum chamber, and an evaporation source can be placed on the substrate. The temperature of the substrate can be set to 40℃~80℃. The evaporation rate of the evaporation source can be 0.1 Å / s~0.5 Å / s. The horizontal distance between the evaporation source and the incident light side 111 can be 30cm~50cm. The evaporation time of the evaporation source can be 100s~1000s.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for fabricating an optical film, characterized in that, It is applied to a vacuum vapor deposition apparatus, the vacuum vapor deposition apparatus including a vacuum chamber, in which a film material source is disposed, and the normal of the film material source is vertically upward; The manufacturing method includes: A substrate is provided, the substrate including a detector array for photoelectric detection, the detector array including an incident light side; The substrate is placed in the vacuum chamber such that the light incident side faces the film material source and is vertically arranged, and the light incident side is located within the film material plume formed by the film material source, so as to form an optical film layer with a thickness that gradually decreases from bottom to top on the light incident side.

2. The method for fabricating an optical film layer according to claim 1, characterized in that, The angle between the normal of the light-incident side and the normal of the film material source is greater than or equal to 70° and less than or equal to 90°.

3. The method for fabricating an optical film layer according to claim 1, characterized in that, The vacuum phase deposition equipment is an electron beam evaporation deposition equipment, and the film material source is an evaporation source.

4. The method for fabricating an optical film layer according to claim 3, characterized in that, The vacuum level of the vacuum chamber is 1×10^ -7 Torr ~ 1×10^ -5 Torr; A substrate is disposed within the vacuum chamber, and the evaporation source is disposed on the substrate. The temperature of the substrate is 40℃~80℃. The evaporation rate of the evaporation source is 0.1 Å / s ~ 0.5 Å / s; The horizontal distance between the evaporation source and the incident light side is 30cm~50cm; The evaporation time of the evaporation source is 100s~1000s.

5. The method for fabricating an optical film layer according to claim 3, characterized in that, The material evaporated by the evaporation source includes at least one of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

6. The method for fabricating an optical film layer according to claim 1, characterized in that, The vacuum phase deposition equipment is a magnetron sputtering deposition equipment, and the film material source is a target material.

7. The method for fabricating an optical film layer according to any one of claims 1-6, characterized in that, Before placing the substrate inside the vacuum chamber, the method further includes forming a passivation layer on the light-incident side.

8. The method for fabricating an optical film layer according to any one of claims 1-6, characterized in that, The detector array is a CMOS array.

9. A filter, characterized in that, The filter includes a filter layer, which is prepared by the optical film preparation method according to any one of claims 1-8.

10. A spectrometer, characterized in that, Includes the filter as described in claim 9.

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