Infrared bandpass filter structure and infrared bandpass filter using the same

Abstract

The present invention provides an infrared bandpass filter structure formed by an alternating stack of a plurality of hydrogenated silicon aluminum layers and a plurality of lower refractive index layers, wherein the plurality of lower refractive index layers are an oxide, and the infrared bandpass filter structure has a passband that at least partially overlaps within a wavelength range of 800nm ​​to 1600nm, and the passband has a central wavelength, and the central wavelength has a magnitude shift of less than 11nm when the incident angle changes from 0° to 30°; an infrared bandpass filter is formed on a first side of a substrate, and an anti-reflection layer is formed on a second side of the substrate opposite to the first side; thereby, the sputtering efficiency can be improved to significantly reduce the manufacturing cost, and the warping of the film layer can be reduced to solve the problem of easy chipping of the corners during post-cutting.

Description

Technical Field

[0001] The present invention relates to the technical field of an infrared bandpass filter structure and the structure of the filter, and in particular to an infrared bandpass filter structure that can improve sputtering efficiency to significantly reduce production costs, and can reduce the warping of the film layer to solve the problem of easy chipping in post-cutting, and an infrared bandpass filter using the structure. Background Art

[0002] Generally, filters can be divided into bandpass filters, short-wave cut-off filters, and long-wave cut-off filters according to their spectral characteristics. Bandpass filters refer to filters that allow light of a specific wavelength band to pass through, while light outside the passband is cut off. They are divided into narrowband and broadband according to bandwidth, usually differentiated by the value of the bandwidth to the central wavelength, less than 5% is narrowband, and greater than 5% is broadband. In order to reduce the interference of ambient visible light, narrowband interference filters are generally used. Traditional RGB visible light cameras need to use infrared cut-off filters to filter out unnecessary low-frequency near-infrared light to prevent infrared light from affecting the visible light part and producing false colors or ripples, while improving effective resolution and color reproduction. However, in order to avoid interference from ambient light, infrared cameras need to use narrowband filters (i.e., infrared bandpass filters) that only allow near-infrared light of a specific wavelength band to pass.

[0003] A commonly known infrared bandpass filter, as shown in Taiwan Patent Publication No. I576617 and No. I648561 "Optical Filter and Sensing System", is mainly formed by an alternating stack of multiple hydrogenated silicon layers and multiple lower refractive index layers. The infrared bandpass filter structure has a passband that at least partially overlaps in the wavelength range of 800nm ​​to 1600nm. The passband has a central wavelength, and the central wavelength shifts in magnitude by about 12.2 to 20nm when the incident angle changes from 0° to 30°. Among them, the multiple hydrogenated silicon layers each have a refractive index greater than (close to) 3.5 in the wavelength range of 800nm ​​to 1100nm, and the multiple lower refractive index layers are an oxide with a refractive index less than 2 in the wavelength range of 800nm ​​to 1100nm, which may include at least one of silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5) and a mixture thereof.

[0004] However, it is generally known that infrared bandpass filters have the following disadvantages in practical implementation:

[0005] 1. The center wavelength of the passband of the infrared band filter formed by the alternating stack of the plurality of hydrogenated silicon layers and the plurality of lower refractive index layers is generally known to have a large offset (about 12.2 to 20 nm) when the incident angle changes from 0° to 30°. Therefore, it is easy to cause the problem of being unable to recognize or failing to recognize when the three-dimensional imaging system is applied to light collection at a large angle.

[0006] 2. The film layer of the commonly known infrared bandpass filter is formed by sputtering a pure silicon target, but the pure silicon target can only be sputtered using a power of 5-6KW. Excessive power will cause the pure silicon target to crack and become unusable. Therefore, it takes a long time to sputter the film layer, resulting in very poor sputtering efficiency, which in turn increases the production cost (such as electricity costs, labor hours, etc.).

[0007] 3. The film layer of the commonly known infrared bandpass filter has a relatively thick thickness, so it will produce a large amount of warping when plated on a glass substrate, resulting in a serious chipping problem in the subsequent cutting process.

[0008] In view of this, the inventor has deeply conceived and actively studied, improved and tried to develop and design the present invention in view of the above-mentioned problems. Summary of the invention

[0009] The main purpose of the present invention is to solve the problems of the commonly known infrared bandpass filter, such as low sputtering efficiency leading to high production cost, and the warping of the film layer leading to easy chipping during post-cutting.

[0010] The infrared bandpass filter structure described in the present invention is formed by an alternating stack of multiple hydrogenated silicon aluminum layers and multiple lower refractive index layers, wherein the multiple lower refractive index layers are an oxide. The infrared bandpass filter structure has a passband that at least partially overlaps within the wavelength range of 800nm ​​to 1600nm, and the passband has a central wavelength. When the incident angle changes from 0° to 30°, the central wavelength shifts in magnitude by less than 11nm.

[0011] The infrared bandpass filter of the present invention mainly forms the infrared bandpass filter structure on a first side surface of a substrate, and forms an anti-reflection layer on a second side surface of the substrate opposite to the first side surface.

[0012] The infrared bandpass filter structure and the infrared bandpass filter using the structure provided by the present invention, wherein the central wavelength of the passband of the infrared bandpass filter structure formed by the alternating stacking of the plurality of hydrogenated silicon aluminum layers and the plurality of lower refractive index layers will have a small offset of less than 11nm when the incident angle changes from 0° to 30°, so it is not easy to have the problem of being unable to recognize or failing to recognize when applied to a three-dimensional imaging system. In particular, when the hydrogenated silicon aluminum is made of a silicon aluminum target doped with aluminum components, it can withstand more than 2 times the power output (about 10-20KW) than the hydrogenated silicon made of the commonly known pure silicon target, so the coating time can be shortened by at least half, and the corresponding output can be more than doubled at the same time, resulting in the resource costs including the whole factory production time, manpower, electricity, etc. will also be reduced by half, greatly improving the competitive advantage. Moreover, the film layer of the infrared bandpass filter structure can be made into a smaller thickness due to the good ductility of the aluminum component, so when it is plated on a glass substrate, the smaller the film thickness, the relatively smaller the internal stress. The small internal stress can reduce the occurrence of chipping in the subsequent cutting process, thereby improving the yield of the cutting process and further achieving the purpose of reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a cross-sectional schematic diagram of the infrared bandpass filter of the present invention;

[0014] Figure 2 A schematic diagram of the structure of a vacuum sputtering reactive coating system for coating process of the present invention;

[0015] Figure 3 It is a schematic diagram of the film structure of the first embodiment of the infrared bandpass filter structure of the present invention;

[0016] Figure 4 is a spectrum diagram of the first embodiment of the infrared bandpass filter structure of the present invention;

[0017] Figure 5 A schematic diagram of the film structure of Experiment 1 of the second embodiment of the infrared bandpass filter structure of the present invention;

[0018] Figure 6 is a spectrum diagram of Experiment 1 of the second embodiment of the infrared bandpass filter structure of the present invention;

[0019] Figure 7 A schematic diagram of the film structure of Experiment 2 of the second embodiment of the infrared bandpass filter structure of the present invention;

[0020] Figure 8 It is a spectrum diagram of Experiment 2 of the second embodiment of the infrared bandpass filter structure of the present invention;

[0021] Fig. 9 It is a schematic diagram of the film structure of the third embodiment of the infrared bandpass filter structure of the present invention;

[0022] Fig.10 is a spectrum diagram of the third embodiment of the infrared bandpass filter structure of the present invention;

[0023] Fig.11 It is a film layer structure diagram of a visible light reflectivity experiment of the infrared bandpass filter structure of the present invention;

[0024] Fig.12 It is a spectrum diagram of the visible light reflectivity experiment of the infrared bandpass filter structure of the present invention;

[0025] Fig.13 This is a color coordinate range diagram of a visible light reflectivity experiment of the infrared bandpass filter structure of the present invention. DETAILED DESCRIPTION

[0026] See also Figure 1 As shown, the infrared bandpass filter of the present invention comprises a substrate 10, an infrared bandpass filter structure 20 and an anti-reflection (AR) layer 30, wherein:

[0027] The substrate 10 is made of glass and has a first side surface and a second side surface opposite to the first side surface.

[0028] The infrared bandpass filter structure 20 is formed on the first side of the substrate 10, and is formed by alternately stacking a plurality of hydrogenated silicon aluminum (SiAl:H) layers 21 and a plurality of lower refractive index layers 22, so that the infrared bandpass filter structure 20 has a passband that at least partially overlaps in the wavelength range of 800nm ​​to 1600nm, and the passband has a central wavelength, and the central wavelength shifts in magnitude by less than 11nm (about 10.3-10.5nm) when the incident angle changes from 0° to 30°. In addition, the infrared bandpass filter structure 20 has a thickness of 3000-5500nm, has a high OD value in the wavelength range of 350nm to 1600nm, has a high transmittance in the wavelength range of 800nm ​​to 1600nm, has a color coordinate at 0.2-0.5 on the x-axis and 0.2-0.5 on the y-axis in the visible light range, and has a reflectivity of less than 20%. The refractive index of the plurality of hydrogenated silicon aluminum layers 21 in the wavelength range of 800nm ​​to 1600nm is 3.1-3.6, the extinction coefficient is 1.E-4-1.E-6, and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The lower refractive index layer 22 is an oxide, which includes at least one of silicon dioxide aluminum (SiAl:O2), silicon aluminum nitride (SiAl:N), silicon nitride (SiN), silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5) and a mixture thereof. Moreover, the refractive index of the plurality of lower refractive index layers 22 in the wavelength range of 800nm ​​to 1600nm is less than 1.8, the extinction coefficient is less than 0.0005, and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005.

[0029] The anti-reflection layer 30 is formed on the second side of the substrate 10, and is stacked by a plurality of high refractive index materials, such as hydrogenated silicon aluminum (SiAl:H) and a plurality of low refractive index materials. The low refractive index material includes at least one of silicon dioxide aluminum (SiAl:O2), silicon aluminum nitride (SiAl:N), silicon nitride (SiN), silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5) and a mixture thereof, and has a thickness of 3000nm to 6000nm.

[0030] See also Figure 2As shown in FIG. 1 , it is pointed out that the sputtering process of the hydrogenated silicon aluminum film layer 21 of the present invention is carried out in a vacuum sputtering reaction coating system 40, which mainly uses silicon cylindrical targets of various structures doped with 200ppm to 1500ppm of aluminum as the sputtering target material 45. The manufacturing process is as follows: (A) a clean substrate 10 is placed on a roller 41 with the coating surface facing outward; (B) the roller 41 is rotated at a constant speed in the coating chamber 42; (C) when the vacuum degree is between 10-3 and 10-4Pa, the sputtering source 43 is turned on and argon is passed through. The gas and argon are ionized to form plasma, which bombards the silicon aluminum target 45 under the action of the electric and magnetic fields, and the silicon aluminum material is sputtered onto the substrate 10 to form a silicon aluminum film; (D) As the roller 200 rotates, the substrate 100 is brought to the reaction source (RF / ICP) area 44; (E) Hydrogen, oxygen and argon are introduced into the reaction source area 44 to form plasma, which moves toward the substrate 10 at a high speed under the action of the electric field, and finally reacts with the silicon aluminum film on the substrate 10 to form a hydrogenated silicon aluminum film layer 21. Among them, when preparing a high refractive index film, by adjusting the proportion (flow rate) of hydrogen in the mixed gas filled in the reaction source area 44, a film with a maximum refractive index gradually changing from 3.1 to 4 from 800nm ​​to 1600nm and an extinction coefficient less than 0.0005 can be prepared. When the gas filled into the reaction source region 44 is a mixed gas of oxygen and argon, a thin film can be prepared whose refractive index gradually changes from 1.46 to 1.7 from 350nm to 1600nm and whose extinction coefficient can be less than 0.0005.

[0031] Please refer to Figures 3 and 4, which are the first embodiment (850 bandpass filter) of the infrared bandpass filter structure of the present invention. It is composed of 27 layers of hydrogenated silicon aluminum layers and silicon dioxide aluminum layers stacked on each other, and the stacking thickness is about 3500nm. Among them, the refractive index of the silicon oxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is greater than 3 and close to 3.6, the extinction coefficient is less than 0.0005, and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The refractive index of the silicon dioxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is less than 1.8, and the extinction coefficient is less than 0.0005. The infrared bandpass filter structure formed by stacking has a passband that at least partially overlaps in the wavelength range of 800nm ​​to 1600nm, and the central wavelength of the passband shifts by less than 11nm when the incident angle changes from 0° to 30°. When it is applied to a three-dimensional imaging system, it can improve the three-dimensional image resolution capability.

[0032] Please refer to Figures 5 and 6, which are Experiment 1 (940 bandpass filter) of the second embodiment of the infrared bandpass filter structure of the present invention. It is composed of 31 layers of hydrogenated silicon aluminum layers and silicon dioxide aluminum layers stacked on each other, and the stacking thickness is about 4000nm. Among them, the refractive index of the silicon oxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is greater than 3 and close to 3.6, the extinction coefficient is less than 0.0005, and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The refractive index of the silicon dioxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is less than 1.8, and the extinction coefficient is less than 0.0005. The infrared bandpass filter structure formed by stacking has a passband that at least partially overlaps in the wavelength range of 800nm ​​to 1600nm, and the central wavelength of the passband shifts by less than 11nm when the incident angle changes from 0° to 30°. When it is applied to a three-dimensional imaging system, it can improve the three-dimensional image resolution capability.

[0033] Please refer to Figures 7 and 8, which are Experiment 2 (940 bandpass filter) of the second embodiment of the infrared bandpass filter structure of the present invention. It is composed of 35 layers of hydrogenated silicon aluminum layers and silicon dioxide aluminum layers stacked on each other, and the stacking thickness is about 4000-550nm. Among them, the refractive index of the silicon oxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is greater than 3 and close to 3.6, and the extinction coefficient is less than 0.0005, and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The refractive index of the silicon dioxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is less than 1.8, and the extinction coefficient is less than 0.0005. The infrared bandpass filter structure formed by the stack has a passband that at least partially overlaps in the wavelength range of 800nm ​​to 1600nm. The center wavelength of the passband shifts by less than 11nm when the incident angle changes from 0° to 30°. Its T90-T10% slope is better than that of Example 1 (the slope of Experiment 1 is less than 8 and the slope of Experiment 2 is less than 7), and the OD value at the same position is also better than that of Example 1.

[0034] Please refer to Figures 9 and 10, which are the third embodiment (1064 bandpass filter) of the infrared bandpass filter structure of the present invention, which is composed of 33 layers of hydrogenated silicon aluminum layers and silicon dioxide aluminum layers stacked on each other, and the stacking thickness is less than 5000nm. Among them, the refractive index of the silicon oxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is greater than 3 and close to 3.6, and the extinction coefficient is less than 0.0005, and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The refractive index of the silicon dioxide aluminum layer in the wavelength range of 800nm ​​to 1600nm is less than 1.8, and the extinction coefficient is less than 0.0005. The infrared bandpass filter structure formed by the stack has a passband that at least partially overlaps in the wavelength range of 800nm ​​to 1600nm. The center wavelength of the passband shifts by less than 2nm when the incident angle changes from 0° to 7°. When the passband incident angle in the wavelength ranges of 400 to 1000nm and 1120 to 1600 changes from 0° to 7°, OD>3.

[0035] Please refer to Figures 11 to 13, which are visible light reflectivity experiments of the infrared bandpass filter structure of the present invention. The structure is composed of 37 layers of hydrogenated silicon aluminum layers and silicon dioxide aluminum layers stacked on each other. Its color coordinates are at Rx Coordinate 0.2 to 0.5 and Ry Coordinate 0.2 to 0.5 in the visible light range, and its reflectivity is less than 20%.

[0036] The infrared bandpass filter structure and the infrared bandpass filter using the structure provided by the present invention have the following advantages:

[0037] 1. The central wavelength of the passband of the infrared band filter structure 20 formed by the alternating stacking of the plurality of hydrogenated silicon aluminum layers 21 and the plurality of lower refractive index layers 22 of the present invention will have a small offset (about 10.3-10.5 nm) of less than 11 nm when the incident angle changes from 0° to 30°. Therefore, when applied to a three-dimensional imaging system, it is not easy to cause the problem of non-recognition or recognition failure.

[0038] 2. The aluminum-doped silicon-aluminum target of the present invention can withstand more than twice the power output (about 10-20KW) than the commonly known pure silicon target, so the coating time can be shortened by at least half, and the output can be more than doubled at the same time, resulting in a reduction of half of the resource costs including the entire factory production time, manpower, electricity, etc., greatly improving the competitive advantage.

[0039] 3. The film layer of the present invention can be made into a smaller thickness by taking advantage of the good ductility of the aluminum component. Therefore, when plated on a glass substrate, the smaller the film thickness, the smaller the internal stress. The smaller the internal stress, the smaller the chipping in the subsequent cutting process, thereby improving the yield of the cutting process and further achieving the purpose of reducing costs.

[0040] In summary, since the present invention has the above-mentioned advantages and practical value, and no similar products have been published among similar products, it has met the application requirements for invention patents, and an application is submitted in accordance with the law.

[0041]

Explanation of symbols

[0042] 10 substrates

[0043] 20 infrared bandpass filter structure 21 silicon oxide aluminum layer

[0044] 22 Lower refractive index layer

[0045] 30 Anti-reflective layer

[0046] 40 Vacuum sputtering reactive coating system 41 Roller

[0047] 42 coating chamber 43 sputtering source

[0048] 44 reaction source area 45 target material

Claims

1. An infrared bandpass filter structure, characterized in that: The infrared bandpass filter structure is formed by alternately stacking a plurality of hydrogenated silicon aluminum (SiAl:H) layers and a plurality of lower refractive index layers having a lower refractive index than the plurality of hydrogenated silicon aluminum layers, wherein the plurality of lower refractive index layers are an oxide, and the infrared bandpass filter structure has a passband that at least partially overlaps within a wavelength range of 800 nm to 1600 nm, wherein the passband has a central wavelength, and when the incident angle changes from 0° to 30°, the central wavelength shifts in magnitude by less than 11 nm; The plurality of lower refractive index layers include at least one of silicon dioxide aluminum (SiAl:O2), silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5) and mixtures thereof.

2. The infrared bandpass filter structure according to claim 1, characterized in that: The thickness of the infrared bandpass filter structure is 3000-5500nm.

3. The infrared bandpass filter structure according to claim 1, characterized in that: The infrared bandpass filter structure has a high OD value within a wavelength range of 350nm to 1600nm, and has a high transmittance within a wavelength range of 800nm ​​to 1600nm.

4. The infrared bandpass filter structure according to claim 1, characterized in that: The infrared bandpass filter structure has a color coordinate of 0.2-0.5 on the X-axis and 0.2-0.5 on the Y-axis in the visible light range, and a reflectivity lower than 20%.

5. The infrared bandpass filter structure according to claim 1, characterized in that: The refractive index of the multiple hydrogenated silicon aluminum layers in the wavelength range of 800nm ​​to 1600nm is 3.1 to 3.6, the extinction coefficient is 1×10^(-4) to 1×10^(-6), and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.

005.

6. The infrared bandpass filter structure according to claim 1, characterized in that: The refractive index of the plurality of lower refractive index layers in the wavelength range of 800 nm to 1600 nm is less than 1.8, and the extinction coefficient is less than 0.0005.

7. An infrared bandpass filter, characterized in that: include: A substrate having a first side surface and a second side surface opposite to the first side surface; an infrared bandpass filter structure formed on the first side of the substrate, formed by alternately stacking a plurality of hydrogenated silicon aluminum (SiAl:H) layers and a plurality of lower refractive index layers, wherein the plurality of lower refractive index layers are oxides, the infrared bandpass filter structure having a passband at least partially overlapping in the wavelength range of 800 nm to 1600 nm, the passband having a central wavelength, and the central wavelength shifts in magnitude by less than 11 nm when the incident angle changes from 0° to 30°; and an anti-reflection (AR) layer formed on the second side of the substrate; The plurality of lower refractive index layers include at least one of silicon dioxide aluminum (SiAl:O2), silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5) and mixtures thereof.

8. The infrared bandpass filter according to claim 7, characterized in that: The thickness of the infrared bandpass filter structure is 3000-5500nm.

9. The infrared bandpass filter according to claim 7, characterized in that: The infrared bandpass filter structure has a high OD value within a wavelength range of 350nm to 1600nm, and has a high transmittance within a wavelength range of 800nm ​​to 1600nm.

10. The infrared bandpass filter according to claim 7, characterized in that: The infrared bandpass filter structure has a color coordinate of 0.2-0.5 on the x-axis and 0.2-0.5 on the y-axis in the visible light range, and a reflectivity lower than 20%.

11. The infrared bandpass filter according to claim 7, characterized in that: The refractive index of the multiple hydrogenated silicon aluminum layers in the wavelength range of 800nm ​​to 1600nm is 3.1 to 3.6, the extinction coefficient is 1×10^(-4) to 1×10^(-6), and the extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.

005.

12. The infrared bandpass filter according to claim 7, characterized in that: The plurality of lower refractive index layers have a refractive index of less than 1.8 and an extinction coefficient of less than 0.0005 within a wavelength range of 800 nm to 1600 nm, and an extinction coefficient of greater than 0.005 within a wavelength range of 350 nm to 700 nm.

13. The infrared bandpass filter according to claim 7, characterized in that: The anti-reflection layer is formed by stacking a plurality of high refractive index materials, hydrogenated silicon aluminum (SiAl:H) and a plurality of low refractive index materials, wherein the low refractive index materials include at least one of silicon dioxide aluminum (SiAl:O2), silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5) and a mixture thereof.

14. The infrared bandpass filter according to claim 7, characterized in that: The thickness of the anti-reflection layer is 3000nm-6000nm.

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