WO2020244222A1 - Near-infrared bandpass filter, preparation method thereof and optical sensing system - Google Patents

Abstract

A near-infrared bandpass filter, a preparation method and an optical sensing system. The near-infrared bandpass filter comprises: a substrate (51), a primary film system (52) and a secondary film system (53), wherein the primary film system (52) is arranged on a first side of the substrate (51), the secondary film system (53) is arranged on a second side of the substrate (51), and the second side is opposite to the first side; the primary film system (52) comprises a high refractive index silicon germanium base film layer and a low refractive index film layer arranged according to a first preset stacking structure; the secondary film system (53) comprises a high refractive index silicon germanium base film layer and a low refractive index film layer arranged according to a second preset stacking structure; the adhesion force of the primary film system (52) and the secondary film system (53) to the substrate (51) is greater than or equal to 15MPa, and meets that the ISO level is less than or equal to 1 under the ISO2409-1992 standard.

Description

Near-infrared bandpass filter, preparation method thereof and optical sensing system

Cross references to related applications

This application is required to be submitted to the China National Intellectual Property Office (CNIPA) on June 5, 2019, with the application number 201910488156.1, and the invention title of "Near-infrared bandpass filter and its preparation method and optical sensing system" The priority and rights of the invention patent application, the Chinese invention patent application is incorporated herein by reference in its entirety.

Technical field

This application relates to the field of optical elements, and more specifically, to a near-infrared bandpass filter, a preparation method thereof, and an optical sensing system.

Background technique

The infrared sensor system forms an image by receiving the infrared rays reflected by the target, and then obtains the target's information by processing the image. It is usually used in fields such as face recognition, gesture recognition, and smart home. The infrared sensor system includes components such as lenses, filters, and image sensors. In this field, filters with excellent performance are required to achieve high image quality.

For example, the near-infrared bandpass filters involved in products such as automotive laser radars need to work normally and stably under a wide operating temperature and high humidity. Therefore, such filters have higher requirements for film firmness and the like.

Summary of the invention

This application provides a near-infrared bandpass filter and an optical sensing system.

In the first aspect, an embodiment of the present application provides a near-infrared bandpass filter, comprising: a substrate, a main film system and an auxiliary film system, the main film system is located on a first side of the substrate, and the The auxiliary film system is located on the second side of the substrate, and the second side is opposite to the first side; the main film system includes a high refractive index silicon germanium-based film layer arranged in a first preset stack structure and Low refractive index film layer; the auxiliary film system includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged according to a second preset stack structure, the main film system and the auxiliary film system and the The adhesion of the substrate is greater than or equal to 15Mpa, and meets the ISO level less than or equal to level 1 under the ISO2409-1992 standard.

In one embodiment, the high refractive index silicon germanium-based film layer includes silicon hydride, germanium hydride, silicon borohydride, germanium borohydride, nitrogen-doped silicon hydride, nitrogen-doped germanium hydride, phosphorus-doped silicon hydride, and phosphorus-doped germanium hydride. , Si _X Ge _1-X and Si _X Ge _1-X : one of H or their mixture.

In one embodiment, the extinction coefficient of the high refractive index silicon germanium-based film layer is less than 0.01 in the wavelength range of 780 nm to 1200 nm.

In one embodiment, the low refractive index film layer includes one of SiO ₂ , Si ₃ N ₄ , SiO _X N _Y , Ta ₂ O ₅ , Nb ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , SiCN, and SiC Or a mixture of them.

In one embodiment, the substrate is made of glass with a thermal expansion coefficient of 3×10 ^-6 to 17×10 ^-6 /K.

In one embodiment, the glass includes one or more of D263T, AF32, Eagle XG, H-ZPK5, and H-ZPK7.

In one embodiment, in the temperature range of -30°C to 85°C, the temperature drift of the center wavelength of the passband of the near-infrared bandpass filter is less than 0.09nm/°C.

In one embodiment, the main film system is a narrow band pass film system, and the auxiliary film system is a wide band pass film system or a long wave pass film system.

In one embodiment, in the wavelength range of 780nm-1200nm, the auxiliary film system has at least one cutoff band and at least one passband.

In one embodiment, the auxiliary film system is a broadband pass film system, and the pass band of the broadband pass film system covers the pass band of the narrow band pass film system.

In the second aspect, the embodiments of the present application provide a near-infrared bandpass filter, comprising: a substrate, a main film system and an auxiliary film system, the main film system is located on the first side of the substrate, and the auxiliary film system is located on the first side of the substrate. On the second side, the second side is opposite to the first side. The main film system and auxiliary film system do not separate from the substrate after the near-infrared band-pass filter is cooked over boiling water for 6-10 hours.

In one embodiment, the near-infrared band-pass filter has less than 10 apparent point defects with an average length less than or equal to 40 microns on both sides of the near-infrared bandpass filter.

In an embodiment, the cut-off degree of the cut-off band of the near-infrared band-pass filter in the 350nm-1100nm waveband is greater than 5.

In a third aspect, the embodiments of the present application also provide an optical sensing system, including an image sensor and the aforementioned near-infrared band-pass filter, the near-infrared band-pass filter is arranged on the photosensitive side of the image sensor.

In a fourth aspect, the embodiments of the present application also provide a method for preparing a near-infrared bandpass filter, the method comprising: extracting a coating chamber filled with a substrate, a main film target material, and an auxiliary film target material. Vacuum; using argon gas as a sputtering gas to sputter the main film on the first side of the substrate by sputtering; and on the first side of the substrate by vapor deposition or the sputtering method The auxiliary film system is plated on the opposite second side, wherein the flow rate of the argon gas is above 45 sccm and the sputtering power in the sputtering method is below 10,000 kW.

In one embodiment, the sputtering main film system includes: charging the argon gas at a flow rate of 20sccm-50sccm and bombarding the SiN target with a sputtering power of 2000kW-10000kW to form a SiNC film; and charging at a flow rate of more than 40sccm The argon gas is introduced, hydrogen gas is charged at a flow rate of 60 sccm or less, and sputtering is performed with a sputtering power of 4000 kW-10000 kW to form a Si:H film.

In one embodiment, the sputtering main film system includes: charging the argon gas at a flow rate of 20sccm-50sccm, charging oxygen gas at a flow rate of less than 80sccm, and bombarding the Si target with a sputtering power of 2000kW-10000kW to form SiO ₂ film; and filling the argon gas at a flow rate of more than 40 sccm and bombarding the Si target and the Ge target with a sputtering power of 4000kW-10000kW to form a Si _X Ge _1-X film.

In one embodiment, the sputtering main film system includes: charging the argon gas at a flow rate of 20sccm-50sccm, charging oxygen gas at a flow rate of less than 80sccm, and bombarding the Si target with a sputtering power of 2000kW-10000kW to form SiO ₂ film; and filling the argon gas at a flow rate of more than 40 sccm, hydrogen gas at a flow rate of less than 60 sccm, and bombarding the Ge target with a sputtering power of 4000kW-10000kW to form a Ge:H film.

In one embodiment, the auxiliary film plating system includes: charging the argon gas at a flow rate of 20sccm-50sccm and bombarding the SiN target with a sputtering power of 2000kW-10000kW to form a SiNC film; and charging at a flow rate of more than 40sccm The argon gas is filled with hydrogen gas at a flow rate of 60 sccm or less and sputtered with a sputtering power of 4000kW-10000kW to form a Si:H film.

In one embodiment, the auxiliary film plating system includes: filling the argon gas at a flow rate of 20 sccm-50 sccm, filling oxygen gas at a flow rate of less than 80 sccm, and bombarding the Si target with a sputtering power of 2000kW-10000kW to form SiO ₂ And the argon gas is charged at a flow rate of more than 40 sccm and the Si target and the Ge target are bombarded with a sputtering power of 4000kW-10000kW to form a Si _X Ge _1-X film.

In one embodiment, the auxiliary film coating system includes: under a vacuum of less than 1×10 ^-4 Pa, oxygen is charged at a flow rate of 130 sccm or less, argon is charged at a flow rate of 30 sccm or less, and ion beam assisted deposition Evaporation film material silicon ring and titanium oxide.

The near-infrared bandpass filter provided by the present application has excellent color filtering performance and structural stability.

Description of the drawings

By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present application will become more apparent:

Fig. 1 shows a schematic structural diagram of a near-infrared bandpass filter according to an embodiment of the present application;

Fig. 2 shows the light transmittance curve of the near-infrared band-pass filter according to Embodiment 1 of the present application;

FIG. 3 shows the light transmittance curve of the near-infrared bandpass filter according to Embodiment 2 of the present application;

FIG. 4 shows the light transmittance curve of the near-infrared bandpass filter according to Embodiment 3 of the present application; and

Fig. 5 shows a schematic diagram of the use state of the optical sensing system according to an embodiment of the present application.

Detailed ways

In order to better understand the application, various aspects of the application will be described in more detail with reference to the drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that in this specification, expressions such as first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any restriction on the feature. Therefore, without departing from the teaching of the present application, the first preset stack structure discussed below may also be referred to as the second preset stack structure. vice versa.

In the drawings, for ease of description, the thickness, size, and shape of components have been slightly adjusted. The drawings are only examples and are not drawn strictly to scale. For example, the ratio between the thickness and the length of the first film system is not in accordance with the ratio in actual production. As used herein, the terms "approximately", "approximately", and similar terms are used as terms indicating approximation, not as terms indicating degree, and are intended to describe measured values that will be recognized by those of ordinary skill in the art. Or the inherent deviation in the calculated value.

In this context, the thickness of the film layer refers to the thickness in the direction away from the substrate.

It should also be understood that the terms "including", "including", "having", "including" and/or "including", when used in this specification, mean that the stated features, elements and/or components are present , But does not exclude the presence or addition of one or more other features, elements, components and/or their combinations. In addition, when expressions such as "at least one of" appear after the list of listed features, the entire listed feature is modified instead of individual elements in the list. In addition, when describing the embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including engineering terms and scientific and technological terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. It should also be understood that, unless clearly stated in this application, words defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of related technologies, and should not be idealized or excessive Formal interpretation of meaning.

It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other if there is no conflict. In addition, unless clearly defined or contradictory to the context, the specific steps included in the method described in this application are not necessarily limited to the described order, and can be performed in any order or in parallel. Hereinafter, the present application will be described in detail with reference to the drawings and in conjunction with embodiments.

Fig. 1 shows a schematic structural diagram of a near-infrared bandpass filter according to an embodiment of the present application. 1, the near-infrared bandpass filter provided by the embodiment of the present application includes: a substrate 51, a main film system 52, and an auxiliary film system 53, the main film system 52 is located on the first side of the substrate 51, and the auxiliary film system 53 is located on the second side of the substrate, and the first side and the second side are opposite. The adhesion of the main film system and the auxiliary film system to the substrate is greater than or equal to 15Mpa, and meets the ISO grade less than or equal to level 1 (equivalent to ASTM level greater than or equal to 4B) under the ISO2409-1992 standard.

The main film system 52 may include a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a first preset stack structure. The first preset stack structure can be expressed as L(HL)^s. The auxiliary film system 53 may include a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a second preset stack structure. The second preset stack structure can be expressed as L(HL)^p. In the above representation, L represents a low refractive index film layer, H represents a high refractive index silicon germanium-based film layer, s and p represent the number of repetitions of HL stacking, and s≠p can be satisfied.

The substrate 51 is a transparent substrate. For example, the material of the transparent substrate can optionally be crystal, borosilicate glass, or the like. The substrate 51 may be made of glass having a thermal expansion coefficient of 3×10 ^-6 to 17×10 ^-6 /K. Specifically, the substrate 51 may be made of one or more of D263T, AF32, Eagle XG, H-ZPK5, H-ZPK7, and the like. Illustratively, the base 51 may be a transparent sheet, the up-down direction in FIG. 1 is the thickness direction of the transparent sheet, and the upper side and the lower side of the transparent sheet are opposite. The main film system 52 is disposed on the outside of the upper surface of the base 51, and the auxiliary film system 53 is disposed on the outside of the lower surface of the base 51.

The main film system 52 may include a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a first preset stack structure. When corresponding to the same wavelength, the refractive index n _{1 of the} high refractive index silicon germanium-based film layer may be greater than the refractive index n _{2 of the} low refractive index film layer. Along the direction away from the substrate 51, the form of the first preset stack structure may be: L(HL)^s. H represents a high refractive index silicon germanium-based film layer, L represents a low refractive index film layer, s represents the number of repetitions of the structural form in parentheses, and s is an integer greater than or equal to 1. Exemplarily, when s is 5, the form of the first preset stack structure may be: LHLHLHLHLHL.

The auxiliary film system 53 may include a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a second preset stack structure. When corresponding to the same wavelength, the refractive index n _{1 of the} high refractive index silicon germanium-based film layer may be greater than the refractive index n _{2 of the} low refractive index film layer. Similarly, along the direction away from the substrate 51, the form of the second preset stack structure may be: L(HL)^p. H represents a high refractive index silicon germanium-based film layer, L represents a low refractive index film layer, p represents the number of repetitions of the structure in parentheses, and p is an integer greater than or equal to 1. Exemplarily, when p is 4, the form of the second preset stack structure may be: LHLHLHLHL.

Each layer of the main film system 52 can be a film layer generated by sputtering reaction, and each film layer of the auxiliary film system 53 can be a film layer generated by a sputtering reaction method or an evaporation method. This manufacturing method makes the base 51, the main The film system 52 and the auxiliary film system 53 are combined into one body.

In the wavelength range of 780nm-1200nm, the refractive index of the high refractive index silicon germanium-based film layer of the near-infrared bandpass filter disclosed in the embodiments of the present application may be greater than 3, and the refractive index of the low refractive index film layer may be less than 3. .

In the wavelength range of 780nm-1200nm, the refractive index of the high refractive index silicon germanium-based film layer may be greater than 3, and the refractive index of the low refractive index film layer may be less than 3.

In the wavelength range of 780nm-1200nm, the extinction coefficient of the high refractive index silicon germanium-based film layer can be less than 0.01. By setting the extinction coefficient, the light transmittance of the high refractive index silicon germanium base film can be increased, the light loss in the pass band of the high refractive index silicon germanium base film can be reduced, and the light passing through the near-infrared band pass filter can be improved The intensity of the signal improves the clarity of the signal.

In the temperature range of -30°C to 85°C, the temperature drift of the center wavelength of the pass band of the near-infrared bandpass filter can be less than 0.09nm/°C. In a working environment with large temperature changes, the light passing through the near-infrared bandpass filter disclosed in this application contains near-infrared light in a stable area. The signal carried by the near-infrared light in the stable area is stabilized.

The main film system 52 may be a narrow band pass film system, and the auxiliary film system 53 may be a wide band pass film system or a long wave pass film system. For example, the auxiliary film system 53 is a wide band pass film system, and the pass band of the wide band pass film system covers the pass band of the main film system 52 as a narrow band pass film system.

In an exemplary embodiment, the material of the high refractive index silicon germanium-based film layer includes silicon hydride, germanium hydride, silicon borohydride, germanium borohydride, nitrogen-doped silicon hydride, nitrogen-doped germanium hydride, phosphorus-doped silicon hydride, A mixture of one or more of germanium phosphide or Si _X Ge _1-X , wherein 0<X<1. Exemplarily, Si _X Ge _1-X is Si _0.4 Ge _0.6 . Exemplarily, the mixture can be silicon germanium hydride, and the ratio of silicon to germanium can be any ratio; the mixture can be nitrogen-doped silicon germanium hydride, or boron-doped phosphorus-doped germanium hydride.

In an exemplary embodiment, the material of the low refractive index film layer, the material of the second low refractive index film layer, and the material of the third low refractive index film layer each include SiO ₂ , Si ₃ N ₄ , SiO _X N _Y , Ta A mixture of one or more of ₂ O ₅ , Nb ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , SiCN, and SiC, where Y=(4-2X)/3,0<X<1. Exemplarily, SiO _X N _Y may be SiON _2/3 . Exemplarily, the mixture is TiO ₂ and Al ₂ O ₃ , or Ta ₂ O ₅ and Nb ₂ O ₅ , or SiO ₂ , SiCN and SiC.

In an exemplary embodiment, the main film system 52 and the auxiliary film system 53 are generated by a sputtering reaction device or an evaporation device.

In the wavelength range of 780 nm-1200 nm, the auxiliary film system 53 may have at least one cut-off band and at least one pass band. The film layer of the auxiliary film system 53 may be a sputtering reactive plating layer.

The method for preparing the above-mentioned near-infrared bandpass filter includes: evacuating a coating chamber filled with a substrate, a main film-based target material, and an auxiliary film-based target material; using argon gas as a sputtering gas in the sputtering method The main film system is sputtered on the first side of the substrate; and the auxiliary film system is plated on the second side of the substrate opposite to the first side by an evaporation method or the sputtering method, wherein the argon The gas flow rate is above 45 sccm and the sputtering power in the sputtering method is below 10,000 kW.

The structure of the near-infrared bandpass filter proposed in this application will be described in detail below with reference to Examples 1-3.

Example 1

In Embodiment 1, a main film system 52 is disclosed, and the stacking sequence and structure of the film layers included in it are shown in Table 1. The layers in Table 1 refer to the layers along the stacking direction. The first layer is the film layer closest to the substrate 51 and the 35th layer is the film layer farthest from the substrate 51. Among the film layers of the main film system 52, the odd-numbered layers are low-refractive-index film layers, and the even-numbered layers are high-refractive-index silicon germanium-based film layers.

The main film system 52 includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a first preset stack structure. The first preset stack structure can be expressed as L(HL)^s. In the above representation, L represents a low refractive index film layer, H represents a high refractive index silicon germanium-based film layer, and s represents the number of times the HL stack is repeated. For example, in Example 1, S=17.

Table 1: A preset stack structure of the main film system (thickness unit: nm)

Floor	1	2	3	4	5
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
thickness	39	220.5	102.83	118.43	73.61
Floor	6	7	8	9	10
Membrane material	Si:H	SiNC	Si:H	SiNC	Si:H

thickness	82.67	110.81	125.06	190.63	241.24
Floor	11	12	13	14	15
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
thickness	79.48	150.7	56.18	272.67	103.84
Floor	16	17	18	19	20
Membrane material	Si:H	SiNC	Si:H	SiNC	Si:H
thickness	244.31	313.36	272.26	76.29	73.39
Floor	twenty one	twenty two	twenty three	twenty four	25
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
thickness	371.49	84.72	26.21	388.09	122.32
Floor	26	27	28	29	30
Membrane material	Si:H	SiNC	Si:H	SiNC	Si:H
thickness	66.8	382.21	142.68	191.9	262.73
Floor	31	32	33	34	35
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
thickness	118.05	64.98	330.7	167.58	29.4

A method of plating the main film system 52 includes the following steps.

First, vacuum the coating chamber filled with the target and substrate. Preferably, the degree of vacuum may be less than 5×10 ^-5 Torr. The coating chamber can be heated after being evacuated. Preferably, the temperature can be heated to above 130°C.

Then, the sputtering gas can be filled to bombard the SiN target with plasma generated by glow discharge. Argon gas can be charged as a sputtering gas at a flow rate of 20sccm-50sccm. The sputtering power can be set at 2000kW-10000kW to form SiNC by sputtering coating.

Then, argon gas with a flow rate of more than 40 sccm can be used as a sputtering gas, and hydrogen gas with a flow rate of less than 60 sccm can be used as a reactive gas to sputter the coating at a sputtering power of 4000kW-10000kW to form a Si:H film such as. As mentioned above, alternate coatings are performed in order to finally form alternately arranged layers of high density and high firmness.

In Example 1, an auxiliary film system 53 is disclosed, and the stacking order and structure of the film layers included in it are shown in Table 2. The layers in Table 2 refer to the number of layers along the stacking direction. The first layer is the film layer closest to the substrate 51 and the 29th layer is the film layer farthest from the substrate 51. Among the film layers of the auxiliary film system 53, the odd-numbered layers are low-refractive-index film layers, and the even-numbered layers are high-refractive silicon germanium-based film layers.

The auxiliary film system 53 includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a second preset stack structure. The second preset stack structure can be expressed as L(HL)^p. In the above representation, L represents a low-refractive index film layer, H represents a high-refractive silicon germanium-based film layer, p represents the number of times the HL stack is repeated, and s≠p. For example, in Example 1, p=14.

Table 2: A preset stack structure of auxiliary film system (thickness unit: nm)

Floor	1	2	3	4	5
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
Film thickness	118.99	144.41	121.91	40.98	99.76
Floor	6	7	8	9	10
Membrane material	Si:H	SiNC	Si:H	SiNC	Si:H
Film thickness	38.13	108.77	46.76	96.72	40
Floor	11	12	13	14	15
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
Film thickness	twenty one	105	114.2	162.36	134.9
Floor	16	17	18	19	20
Membrane material	Si:H	SiNC	Si:H	SiNC	Si:H
Film thickness	20	20	20	86.73	41.24
Floor	twenty one	twenty two	twenty three	twenty four	25
Membrane material	SiNC	Si:H	SiNC	Si:H	SiNC
Film thickness	117.94	60.05	45.65	53.89	139.6
Floor	26	27	28	29	To
Membrane material	Si:H	SiNC	Si:H	SiNC	To
Film thickness	44.68	68.27	37.07	262.25	To

A method for plating the auxiliary film system 53 may include the following steps.

First, vacuum the coating chamber filled with the target and substrate. Preferably, the degree of vacuum may be less than 5×10 ^-5 Torr. The coating chamber can be heated after being evacuated. Preferably, the temperature can be heated to above 130°C.

Then, the sputtering gas can be filled to bombard the SiN target with plasma generated by glow discharge. Argon gas can be charged as a sputtering gas at a flow rate of 20sccm-50sccm. The sputtering power can be set at 2000kW-10000kW to form SiNC by sputtering coating.

Then, argon gas with a flow rate of more than 40 sccm can be used as a sputtering gas, and hydrogen gas with a flow rate of less than 60 sccm can be used as a reactive gas to sputter the coating at a sputtering power of 4000kW-10000kW to form a Si:H film such as. As mentioned above, alternate coatings are performed in order to finally form alternately arranged layers of high density and high firmness.

The transmittance curve of the near-infrared band-pass filter of Example 1 is shown in Fig. 2, in which the light with the incident angle of 0° is marked with a solid line and the light with the incident angle of 30° is marked with a broken line.

The near-infrared bandpass filter has at least one passband in the wavelength range of 780nm-1200nm, and the cutoff degree of the cutoff band is OD>5 in the wavelength range of 350nm-1100nm. Here, the cutoff degree is OD (Optical Density)=log ₁₀ (T0/T1), where T0 is the intensity of incident light, and T1 is the intensity of transmitted light. T0 and T1 can be measured by spectrophotometer or spectrometer.

The near-infrared bandpass filter prepared according to Example 1 has excellent film adhesion, and is not easy to peel off or collapse in a high temperature and humid environment.

To test the film adhesion of such a near-infrared bandpass filter, the prepared filter can be clamped by a jig and placed above boiling water for less than 10 hours, such as 6 hours. Specifically, the filter can be placed at a position no more than 5 cm above the boiling water, and stay at this distance no more than 10 hours. Then, the filter can be left in a dry environment until the surface of the filter is dry. The main film system and the auxiliary film system do not separate from the substrate after the near-infrared band-pass filter is cooked over boiling water for 6-10 hours. After that, the film surface to be tested can be placed upwards and the film surface can be bonded with test tape. The adhesive force of the test tape can meet: 4N/mm<adhesion<100N/mm. The test tape can be bonded to the middle part of the stretched film surface, and then the test tape can be quickly pulled off. After that, observe whether there is any peeling or collapse with the naked eye or microscope.

In addition, the near-infrared bandpass filter prepared according to the process conditions of Example 1 generally has less than 10 apparent dot defects with an average length less than or equal to 40 microns on both sides.

Example 2

In Embodiment 2, a main film system 52 is disclosed, and the stacking order and structure of the film layers included in it are shown in Table 3. The layers in Table 3 refer to the layers along the stacking direction. The first layer is the film layer closest to the substrate 51 and the 29th layer is the film layer farthest from the substrate 51. Among the film layers of the main film system 52, the odd-numbered layers are low-refractive-index film layers, and the even-numbered layers are high-refractive-index silicon germanium-based film layers.

The main film system 52 includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a first preset stack structure. The first preset stack structure can be expressed as L(HL)^s. In the above representation, L represents a low refractive index film layer, H represents a high refractive index silicon germanium-based film layer, and s represents the number of times the HL stack is repeated. For example, in Embodiment 2, S=16.

Table 3: A preset stack structure of the main film system (thickness unit: nm)

Floor	1	2	3	4	5
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2
Film thickness	230.8	112	101	285.9	105.7
Floor	6	7	8	9	10
Membrane material	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X
Film thickness	99.5	66	236	102.8	100.9
Floor	11	12	13	14	15
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2
Film thickness	76.7	433.5	96.5	99.3	96
Floor	16	17	18	19	20
Membrane material	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X
Film thickness	434.3	68.9	109.3	93.7	244.3
Floor	twenty one	twenty two	twenty three	twenty four	25
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2
Film thickness	22.8	281.39	98.79	209.72	117.2
Floor	26	27	28	29	30
Membrane material	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X
Film thickness	273.8	75.66	89.02	139.3	128.6
Floor	31	32	33	To	To
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	To	To
Film thickness	218.8	113.7	83.9	To	To

A method of plating the main film system 52 may include the following steps.

First, vacuum the coating chamber filled with Si target, Ge target and substrate. Preferably, the degree of vacuum may be less than 5×10 ^-5 Torr. The coating chamber can be heated after being evacuated. Preferably, the temperature can be heated to above 130°C.

Then, the sputtering gas can be filled to bombard the target with plasma generated by glow discharge. Argon gas with a flow rate of 20 sccm-50 sccm can be used as a sputtering gas, and oxygen gas with a flow rate of 80 sccm or less can be used as a reactive gas to sputter and coat the film at a sputtering power of 2000 kW to 10000 kW to form a film such as SiO ₂ . When it is deposited on the substrate, the ion source is used to bombard and supplement oxygen, and the flow rate in PBS does not exceed 80 sccm.

Then, the sputtering gas can be filled to bombard the target with plasma generated by glow discharge. Argon gas can be charged as a sputtering gas at a flow rate of more than 40 sccm. The sputtering power can be set at 4000kW-10000kW to form the Si _X Ge _1-X film by sputtering coating. As mentioned above, alternate coatings are performed in sequence to finally form alternately arranged layers of high density and high firmness.

In Example 2, an auxiliary film system 53 is disclosed, and the stacking sequence and structure of the film layers included in it are shown in Table 2. The layers in Table 2 refer to the number of layers along the stacking direction. The first layer is the film layer closest to the substrate 51 and the 29th layer is the film layer farthest from the substrate 51. Among the film layers of the auxiliary film system 53, the odd-numbered layers are low-refractive-index film layers, and the even-numbered layers are high-refractive silicon germanium-based film layers.

The auxiliary film system 53 includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a second preset stack structure. The second preset stack structure can be expressed as L(HL)^p. In the above representation, L represents a low refractive index film layer, H represents a high refractive index silicon germanium-based film layer, p represents the number of times the HL stack is repeated, and s≠p. For example, in Example 2, p=14.

Table 4: A preset stack structure of auxiliary film system (thickness unit: nm)

Floor	1	2	3	4	5
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2
thickness	72	134.4	109.2	26	45.1
Floor	6	7	8	9	10
Membrane material	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X
thickness	138.13	67	230	92	29
Floor	11	12	13	14	15
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2
thickness	32.9	159	112.9	136.65	94.1
Floor	16	17	18	19	20
Membrane material	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X
thickness	219	41	132	55.8	54
Floor	twenty one	twenty two	twenty three	twenty four	25
Membrane material	SiO 2	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO2
thickness	119	65	64.5	59.3	139.6
Floor	26	27	28	29	To
Membrane material	Si X Ge 1-X	SiO 2	Si X Ge 1-X	SiO 2	To
thickness	44.68	89	137.07	262.25	To

A method for plating the auxiliary film system 53 may include the following steps.

First, vacuum the coating chamber filled with Si target, Ge target and substrate. Preferably, the degree of vacuum may be less than 5×10 ^-5 Torr. The coating chamber can be heated after being evacuated. Preferably, the temperature can be heated to above 130°C.

Then, the sputtering gas can be filled to bombard the target with plasma generated by glow discharge. Argon gas with a flow rate of 20 sccm-50 sccm can be used as a sputtering gas, and oxygen gas with a flow rate of 80 sccm or less can be used as a reactive gas to sputter and coat the film at a sputtering power of 2000 kW to 10000 kW to form a film such as SiO ₂ . When it is deposited on the substrate, the ion source is used to bombard and supplement oxygen, and the flow rate in PBS does not exceed 80 sccm.

Then, the sputtering gas can be filled to bombard the target with plasma generated by glow discharge. Argon gas can be charged as a sputtering gas at a flow rate of more than 40 sccm. The sputtering power can be set at 4000kW-10000kW to form the Si _X Ge _1-X film by sputtering coating. As mentioned above, alternate coatings are performed in sequence to finally form alternately arranged layers of high density and high firmness.

The transmittance curve of the near-infrared band-pass filter of Example 2 is shown in FIG. 3, in which the light with an incident angle of 0° is marked with a solid line and the light with an incident angle of 30° is marked with a broken line.

The near-infrared bandpass filter has at least one passband in the wavelength range of 780nm-1200nm, and the cutoff degree of the cutoff band is OD>5 in the wavelength range of 350nm-1100nm.

The near-infrared bandpass filter prepared according to Example 2 has excellent film adhesion, and is not easy to peel off or collapse under high temperature and humid environment.

To test the film adhesion of such a near-infrared bandpass filter, the prepared filter can be clamped by a jig and placed above boiling water for less than 10 hours, such as 6 hours. Specifically, the filter can be placed at a position no more than 5 cm above the boiling water, and stay at this distance no more than 10 hours. Then, the filter can be left in a dry environment until the surface of the filter is dry. The main film system and the auxiliary film system do not separate from the substrate after the near-infrared band-pass filter is cooked over boiling water for 6-10 hours. After that, the film surface to be tested can be placed upwards and the film surface can be bonded with test tape. The adhesive force of the test tape can meet: 4N/mm<adhesion<100N/mm. The test tape can be bonded to the middle part of the stretched film surface, and then the test tape can be quickly pulled off. After that, observe whether there is any peeling or collapse with the naked eye or microscope.

In addition, the near-infrared bandpass filter prepared according to the process conditions of Example 2 generally has less than 10 apparent dot defects with an average length of less than or equal to 40 microns on both sides.

Example 3

In Embodiment 3, a main film system 52 is disclosed, and the stacking sequence and structure of the film layers included in it are shown in Table 5. The layers in Table 5 refer to the layers along the stacking direction. The first layer is the film layer closest to the substrate 51 and the 35th layer is the film layer farthest from the substrate 51. Among the film layers of the main film system 52, the odd-numbered layers are low-refractive-index film layers, and the even-numbered layers are high-refractive-index silicon germanium-based film layers.

The main film system 52 includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a first preset stack structure. The first preset stack structure can be expressed as L(HL)^s. In the above representation, L represents a low refractive index film layer, H represents a high refractive index silicon germanium-based film layer, and s represents the number of times the HL stack is repeated. For example, in Example 3, S=17.

Table 5: A preset stack structure of the main film system (thickness unit: nm)

Floor	1	2	3	4	5
Membrane material	SiO 2	Ge:H	SiO 2	Ge:H	SiO 2
thickness	204.1	73.1	193	379.6	115
Floor	6	7	8	9	10
Membrane material	Ge:H	SiO 2	Ge:H	SiO 2	Ge:H
thickness	196.3	111.7	202.6	86	119
Floor	11	12	13	14	15
Membrane material	SiO 2	Ge:H	SiO 2	Ge:H	SiO 2
thickness	107	64.44	112.6	65	107.6
Floor	16	17	18	19	20
Membrane material	Ge:H	SiO 2	Ge:H	SiO 2	Ge:H
thickness	128	64.3	87.5	111.4	103
Floor	twenty one	twenty two	twenty three	twenty four	25
Membrane material	SiO 2	Ge:H	SiO 2	Ge:H	SiO 2
thickness	112`	152	63.5	278	109.9
Floor	26	27	28	29	30
Membrane material	Ge:H	SiO 2	Ge:H	SiO 2	Ge:H
thickness	66.2	106.4	269	140	278.8
Floor	31	32	33	34	35
Membrane material	SiO 2	Ge:H	SiO 2	Ge:H	SiO 2
thickness	110.3	226.9	190.6	105.2	35.38

A method of plating the main film system 52 may include the following steps.

First, vacuum the coating chamber filled with Si target, Ge target and substrate. Preferably, the degree of vacuum may be less than 5×10 ^-5 Torr. The coating chamber can be heated after being evacuated. Preferably, the temperature can be heated to above 130°C.

Then, the sputtering gas can be filled to bombard the target with plasma generated by glow discharge. Argon gas with a flow rate of 20 sccm-50 sccm can be used as a sputtering gas, and oxygen gas with a flow rate of 80 sccm or less can be used as a reactive gas under a sputtering power of 2000 kW to 10000 kW to form a film such as SiO ₂ . When it is deposited on the substrate, the ion source is used to bombard and supplement oxygen, and the flow rate in PBS does not exceed 80 sccm.

Then, the sputtering gas can be charged to bombard the target with plasma generated by glow discharge. Argon can be charged as a sputtering gas at a flow rate of more than 40 sccm, and hydrogen can be charged as a reaction gas at a flow rate of less than 60 sccm. The sputtering power can be set at 4000kW-10000kW to form Ge:H film by sputtering coating. As mentioned above, alternate coatings are performed in order to finally form alternately arranged layers of high density and high firmness.

In Example 3, an auxiliary film system 53 is disclosed, and the stacking sequence and structure of the film layers included in it are shown in Table 6. The layers in Table 6 refer to the layers along the stacking direction. The first layer is the film layer closest to the substrate 51 and the 29th layer is the film layer farthest from the substrate 51. Among the film layers of the auxiliary film system 53, the odd-numbered layers are low-refractive-index film layers, and the even-numbered layers are high-refractive silicon germanium-based film layers.

The auxiliary film system 53 includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a second preset stack structure. The second preset stack structure can be expressed as L(HL)^p. In the above representation, L represents a low refractive index film layer, H represents a high refractive index silicon germanium-based film layer, p represents the number of times the HL stack is repeated, and s≠p. For example, in Example 3, p=15.

Table 6: A preset stack structure of auxiliary film system (thickness unit: nm)

Floor	1	2	3	4	5
Membrane material	TiO 2	SiO 2	TiO 2	SiO 2	TiO 2
Film thickness	65	130	49	172	82
Floor	6	7	8	9	10
Membrane material	SiO 2	TiO 2	SiO 2	TiO 2	SiO 2
Film thickness	129	90	131	79.4	126
Floor	11	12	13	14	15
Membrane material	TiO 2	SiO 2	TiO 2	SiO 2	TiO 2
Film thickness	79.8	128.9	80	127	77
Floor	16	17	18	19	20
Membrane material	SiO 2	TiO 2	SiO 2	TiO 2	SiO 2
Film thickness	125.8	77.8	124.7	79.2	128.9
Floor	twenty one	twenty two	twenty three	twenty four	25
Membrane material	TiO 2	SiO 2	TiO 2	SiO 2	TiO 2
Film thickness	80.1	129.2	79.6	128	78
Floor	26	27	28	29	30

Membrane material	SiO 2	TiO 2	SiO 2	TiO 2	SiO 2
Film thickness	127.3	81	132	80	120
Floor	31	To	To	To	To
Membrane material	TiO 2	To	To	To	To
Film thickness	29.98	To	To	To	To

A method for plating the auxiliary film system 53 may include the following steps.

Evaporative coating can be used. For example, an evaporator can be used for coating. Before coating, the cavity can be heated. Preferably, the heating temperature does not exceed 150°C.

In a cavity with a vacuum degree of less than 1×10 ^-4 Pa, oxygen with a flow rate of no more than 130 sccm and argon with a flow rate of no more than 30 sccm are used as the working gas, and ion beam assisted deposition (IAD) is used to evaporate the film material. The silicon ring and titanium oxide finally form a layer of silicon oxide and titanium oxide alternately arranged with high density and high firmness. When depositing the silicon oxide layer, PBS is needed to supplement oxygen, and the flow rate in PBS does not exceed 130sccm.

The transmittance curve of the near-infrared band-pass filter of Example 3 is shown in FIG. 4, in which the light with an incident angle of 0° is marked with a solid line and the light with an incident angle of 30° is marked with a broken line.

The near-infrared bandpass filter has at least one passband in the wavelength range of 780nm-1200nm, and the cutoff degree of the cutoff band is OD>5 in the wavelength range of 350nm-1100nm.

The near-infrared bandpass filter prepared according to Example 3 has excellent film adhesion, and is not easy to peel off or collapse in a high temperature and humid environment.

To test the film adhesion of such a near-infrared bandpass filter, the prepared filter can be clamped by a jig and placed above boiling water for less than 10 hours, such as 6 hours. Specifically, the filter can be placed at a position no more than 5 cm above the boiling water, and stay at this distance no more than 10 hours. Then, the filter can be left in a dry environment until the surface of the filter is dry. The main film system and the auxiliary film system do not separate from the substrate after the near-infrared band-pass filter is cooked over boiling water for 6-10 hours. After that, the film surface to be tested can be placed upwards and the film surface can be bonded with test tape. The adhesive force of the test tape can meet: 4N/mm<adhesion<100N/mm. The test tape can be bonded to the middle part of the stretched film surface, and then the test tape can be quickly pulled off. After that, observe whether there is any peeling or collapse with the naked eye or microscope.

In addition, the near-infrared bandpass filter prepared according to the process conditions of Example 3 generally has less than 10 apparent dot defects with an average length of less than or equal to 40 microns on both sides.

FIG. 5 shows a schematic diagram of an optical sensing system in use according to an embodiment of the application; referring to FIG. 1 and FIG. 5, the optical sensing system includes a near-infrared bandpass filter 5 and an image sensor 6. A first lens assembly 4 is also provided on the object side of the near-infrared narrowband filter 5. The light emitted or reflected by the target 1 to be tested passes through the first lens assembly 4 and then reaches the near-infrared band-pass filter 5. The light passes through the near-infrared The filtered light formed by the band-pass filter 5 reaches the image sensor 6, and the filtered light triggers the image sensor 6 to form an image signal. The optical sensing system provided with the infrared bandpass filter 5 disclosed in the present application can be applied to at least -150°C to 300°C, and the quality of the formed image is stable.

The optical sensing system may also be an infrared recognition system, including an infrared light source 2 (Infrared Radiation, IR light source), a second lens assembly 3, a first lens assembly 4, a near-infrared bandpass filter 5, and an image sensor 6. The image sensor 6 is a three-dimensional sensor.

The above description is only a preferred embodiment of the application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of protection involved in this application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover the above technical features without departing from the technical concept. Other technical solutions formed by any combination of its equivalent features. For example, the above-mentioned features and the technical features disclosed in this application (but not limited to) with similar functions are mutually replaced to form a technical solution.

Claims (19)

1. A near-infrared bandpass filter, characterized by comprising: a substrate, a main film system and an auxiliary film system, the main film system is located on the first side of the substrate, and the auxiliary film system is located on the substrate On the second side of, the second side is opposite to the first side;

   The main film system includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged according to a first preset stack structure;

   The auxiliary film system includes a high refractive index silicon germanium-based film layer and a low refractive index film layer arranged in a second preset stack structure,

   The adhesion of the main film system and the auxiliary film system to the substrate is greater than or equal to 15Mpa, and meets the ISO level less than or equal to level 1 under the ISO2409-1992 standard.
2. The near-infrared bandpass filter according to claim 1, wherein the high refractive index silicon germanium-based film layer comprises silicon hydride, germanium hydride, silicon borohydride, germanium borohydride, and silicon hydride doped nitrogen. , Nitrogen-doped germanium hydride, phosphorus-doped silicon hydride, phosphorus-doped germanium hydride, Si _X Ge _1-X and Si _X Ge _1-X : H or a mixture thereof.
3. The near-infrared bandpass filter according to claim 1, wherein the extinction coefficient of the high refractive index silicon germanium-based film layer is less than 0.01 in the wavelength range of 780nm-1200nm.
4. The near-infrared bandpass filter according to claim 1, wherein the substrate is made of glass with a thermal expansion coefficient of 3×10 ^-6 to 17×10 ^-6 /K.
5. The near-infrared band-pass filter according to claim 1, wherein the temperature drift of the center wavelength of the pass-band of the near-infrared band-pass filter is less than 0.09nm/°C.
6. The near-infrared bandpass filter according to claim 1, wherein the main film system is a narrow band pass film system, and the auxiliary film system is a broadband pass film system or a long wave pass film system.
7. The near-infrared bandpass filter according to claim 6, wherein the auxiliary film system has at least one cut-off band and at least one pass band in the wavelength range of 780nm-1200nm.
8. The near-infrared bandpass filter according to claim 7, wherein the auxiliary film system is a broadband pass film system, and the passband of the broadband pass film system covers the passband of the narrowband pass film system. .
9. A near-infrared bandpass filter, characterized by comprising: a substrate, a main film system and an auxiliary film system, the main film system is located on the first side of the substrate, and the auxiliary film system is located on the substrate On the second side of, the second side is opposite to the first side,

   Wherein, the main film system and the auxiliary film system do not separate from the substrate after the near-infrared band-pass filter is boiled over boiling water for 6-10 hours.
10. The near-infrared band-pass filter according to claim 9, wherein the near-infrared band-pass filter has less than 10 apparent dot defects with an average length of less than or equal to 40 microns on both sides of the near-infrared band-pass filter.
11. The near-infrared band-pass filter according to claim 9, wherein the cut-off degree of the near-infrared band-pass filter in the 350nm-1100nm band is greater than 5.
12. An optical sensing system, characterized in that the optical sensing system comprises an image sensor and the near-infrared band-pass filter according to any one of claims 1-11, and the near-infrared band-pass filter The light sheet is arranged on the photosensitive side of the image sensor.
13. A method for preparing a near-infrared bandpass filter, characterized in that the method comprises:

    Vacuum the coating chamber filled with the substrate, the main film target and the auxiliary film target;

    Sputtering the main film system on the first side of the substrate by sputtering using argon gas as the sputtering gas; and

    Coating an auxiliary film system on the second side of the substrate opposite to the first side by an evaporation method or the sputtering method,

    Wherein, the flow rate of the argon gas is above 45 sccm and the sputtering power in the sputtering method is below 10000 kW.
14. The method for preparing a near-infrared bandpass filter according to claim 13, wherein the sputtering main film system comprises:

    Fill the argon gas at a flow rate of 20 sccm-50 sccm and bombard the SiN target with a sputtering power of 2000kW-10000kW to form a SiNC film; and

    The argon gas is charged at a flow rate of 40 sccm or more, hydrogen gas is charged at a flow rate of 60 sccm or less, and sputtering is performed with a sputtering power of 4000 kW-10000 kW to form a Si:H film.
15. The method for preparing a near-infrared bandpass filter according to claim 13, wherein the sputtering main film system comprises:

    Filling the argon gas at a flow rate of 20 sccm-50 sccm, filling oxygen gas at a flow rate of 80 sccm or less, and bombarding the Si target with a sputtering power of 2000kW-10000kW to form an SiO2 film; and

    The argon gas is charged at a flow rate of more than 40 sccm, and the Si target and the Ge target are bombarded with a sputtering power of 4000kW-10000kW to form a SiXGe1-X film.
16. The method for preparing a near-infrared bandpass filter according to claim 13, wherein the sputtering main film system comprises:

    Filling the argon gas at a flow rate of 20 sccm-50 sccm, filling oxygen gas at a flow rate of 80 sccm or less, and bombarding the Si target with a sputtering power of 2000kW-10000kW to form an SiO2 film; and

    The argon gas is charged at a flow rate of more than 40 sccm, hydrogen gas is charged at a flow rate of less than 60 sccm, and the Ge target is bombarded with a sputtering power of 4000kW-10000kW to form a Ge:H film.
17. The method for preparing a near-infrared bandpass filter according to any one of claims 13-16, wherein the auxiliary coating film system comprises:

    Fill the argon gas at a flow rate of 20 sccm-50 sccm and bombard the SiN target with a sputtering power of 2000kW-10000kW to form a SiNC film; and

    The argon gas is charged at a flow rate of 40 sccm or more, hydrogen gas is charged at a flow rate of 60 sccm or less, and sputtering is performed with a sputtering power of 4000 kW-10000 kW to form a Si:H film.
18. The method for preparing a near-infrared bandpass filter according to any one of claims 13-16, wherein the auxiliary coating film system comprises:

    Filling the argon gas at a flow rate of 20 sccm-50 sccm, filling oxygen gas at a flow rate of 80 sccm or less, and bombarding the Si target with a sputtering power of 2000kW-10000kW to form an SiO2 film; and

    The argon gas is charged at a flow rate of more than 40 sccm, and the Si target and the Ge target are bombarded with a sputtering power of 4000kW-10000kW to form a SiXGe1-X film.
19. The method for preparing a near-infrared bandpass filter according to any one of claims 13-16, wherein the auxiliary coating film system comprises:

    Under a vacuum degree of less than 1×10-4Pa, oxygen is filled at a flow rate of 130 sccm or less, argon is filled at a flow rate of 30 sccm or less, and an ion beam assisted deposition of silicon ring and titanium oxide as the evaporation film material.

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