TWI706169B - Infrared band pass filter structure and infrared band pass filter using the structure - Google Patents

Abstract

An infrared bandpass filter structure is formed by alternately stacking a plurality of silicon aluminum hydride layers and a plurality of lower refractive index layers. The plurality of lower refractive index layers are oxides. The infrared bandpass filter structure has a wavelength range of 800nm to 1600nm. At least partially overlapping a passband, the passband has a center wavelength, and when the incident angle changes from 0° to 30°, the magnitude of the deviation is less than 11nm; an infrared bandpass filter is attached to The first side surface of a substrate forms the above-mentioned infrared bandpass filter structure, and an anti-reflection layer is formed on a second side surface of the first side opposite to the substrate; thereby, the sputtering efficiency can be improved and the manufacturing cost can be greatly reduced. And it can reduce the warpage of the film to solve the problem of easy chipping after cutting.

Description

Infrared band pass filter structure and infrared band pass filter using the structure

The present invention relates to an infrared bandpass filter structure and the technical field of the filter structure, in particular to a technology that can improve sputtering efficiency to greatly reduce production costs, and can reduce the amount of warpage of the film to solve the problem of easy collapse in post-cutting The infrared band-pass filter structure for angle problems and the infrared band-pass filter using this structure.

Generally, filters can be divided into band-pass filters, short-wave cut-off filters, and long-wave cut-off filters according to their spectral characteristics. Band-pass filter refers to the passage of light in a specific wavelength band, and the light outside the passband is cut off. According to the bandwidth, it is divided into narrowband and broadband. It is usually distinguished by the value of the bandwidth than the central wavelength. Less than 5% is narrowband, and greater than 5 % Is broadband. In order to reduce the interference of ambient visible light, narrow-band interference filters are commonly used. The traditional RGB visible light camera needs to use an infrared cut filter to filter out unnecessary low-frequency near-infrared light, so as to prevent infrared light from affecting the visible light part, producing false colors or ripples, and improving effective resolution and color reproduction. However, the infrared camera needs to use a narrow-band filter (ie, infrared band-pass filter) in order not to be interfered by ambient light, and only allow near-infrared light of a specific band to pass.

A conventional infrared bandpass filter, as shown in the Taiwan Announcement No. I576617 and No. I648561 "Optical Filter and Sensing System" patents, it is mainly composed of a plurality of hydrogenated silicon layers and a plurality of lower refractive index layers alternately stacked Formed, the infrared band-pass filter structure has a passband at least partially overlapping in the wavelength range of 800nm to 1600nm, the passband has a central wavelength, and the central wavelength changes from 0° to 30° when the incident angle is changed, The magnitude of shifts (shifts) is about 12.2-20nm. Wherein, the plurality of hydrogenated silicon layers each have a refractive index greater than (close to) 3.5 in the wavelength range of 800nm to 1100nm, and the plurality of lower refractive index layers are oxides with a refractive index in the wavelength range of 800nm to 1100nm Less than 2, which may include silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ) At least one of its mixtures.

However, the conventional infrared bandpass filter has the following shortcomings in actual implementation:

1. In the prior art, the central wavelength of the passband of the infrared band filter formed by alternately stacking the plural hydrogenated silicon layers and the plural lower refractive index layers will have a larger deviation when the incident angle is changed from 0° to 30° The displacement (approximately 12.2~20nm), so it is easy to cause the problem of unrecognition or recognition failure when it is applied to a three-dimensional imaging system when receiving light at a large angle.

2. The film of the conventional infrared bandpass filter is formed by sputtering with a pure silicon target, while the pure silicon target can only be sputtered with a power of 5-6KW. Excessive power will cause the pure silicon target to become a target It cannot be used due to the phenomenon of cracking, so it takes a lot of time to sputter the film layer, which makes the sputtering efficiency very poor and increases the production cost (such as electricity costs, man-hours, etc.).

3. The film layer of the conventional infrared bandpass filter is thicker Therefore, when it is plated on the glass substrate, it will produce a larger amount of warpage, which may cause serious corner chipping during the subsequent cutting process.

In view of this, the inventor of the present invention developed and designed the present invention in order to solve the above-mentioned problems, and intensively conceived, and actively researched and improved trials.

The main purpose of the present invention is to solve many problems such as low spattering efficiency of conventional infrared band-pass filters leading to high manufacturing costs, and the amount of warpage of the film leading to easy corner chipping during post-cutting.

The infrared band-pass filter structure of the present invention is formed by alternately stacking a plurality of silicon aluminum hydride layers and a plurality of lower refractive index layers, the plurality of lower refractive index layers are oxides, and the infrared band-pass filter structure has a range of 800 nm to The 1600nm wavelength range at least partially overlaps a passband, the passband has a central wavelength, and when the incident angle changes from 0° to 30°, the magnitude deviation is less than 11nm.

The infrared band-pass filter of the present invention mainly forms the above-mentioned infrared band-pass filter structure on a first side surface of a substrate, and an anti-reflection layer is formed on a second side surface opposite to the first side surface of the substrate.

The infrared bandpass filter structure provided by the present invention and the infrared bandpass filter using the structure use the center of the passband of the infrared band filter structure formed by alternately stacking the complex silicon aluminum hydride layer and the plurality of lower refractive index layers When the incident angle is changed from 0° to 30°, the wavelength will have a small offset of less than 11nm. Therefore, when it is applied to a three-dimensional imaging system, the problem of unrecognition or recognition failure is unlikely to occur. In particular, the use of aluminum-doped silicon-aluminum targets to make the silicon-aluminum hydride can be compared to conventional pure silicon targets. The hydrogenated silicon can withstand more than twice the power output (about 10-20KW), so the coating time can be reduced by at least half, and the relative output at the same time can be more than doubled, resulting in the production time of the whole plant, manpower, and electricity The cost of other resources will also be reduced by half, greatly improving the competitive advantage. Moreover, the film of the infrared band-pass filter structure can be made into a smaller thickness due to the good ductility of the aluminum component. Therefore, when the film is plated on a glass substrate, the smaller the film thickness, the lower the internal stress. The small internal stress can reduce the occurrence of chipping in the subsequent cutting process, so as to increase the yield of the cutting process, and relatively further achieve the purpose of reducing costs.

10: substrate

20: Infrared bandpass filter structure

21: Silicon aluminum oxide layer

22: Lower refractive index layer

30: Anti-reflective layer

40: Vacuum sputtering reactive coating system

41: roller

42: Coating chamber

43: Sputtering source

44: Reaction source area

45: target

Figure 1 is a schematic cross-sectional view of the infrared bandpass filter of the present invention.

Figure 2 is a schematic structural diagram of the vacuum sputtering reactive coating system for coating process of the present invention.

Figure 3 is a schematic diagram of the film structure of the first embodiment of the infrared bandpass filter structure of the present invention.

Figure 4 is a spectrum diagram of the first embodiment of the infrared bandpass filter structure of the present invention.

Figure 5 is a schematic diagram of the film structure of Experiment 1 of the second embodiment of the infrared bandpass filter structure of the present invention.

Figure 6 is a spectrum diagram of Experiment 1 of the second embodiment of the infrared bandpass filter structure of the present invention.

FIG. 7 is a schematic diagram of the film structure of Experiment 2 of the second embodiment of the infrared bandpass filter structure of the present invention.

Figure 8 is a spectrum diagram of Experiment 2 of the second embodiment of the infrared bandpass filter structure of the present invention.

Figure 9 is a schematic diagram of the film structure of the third embodiment of the infrared bandpass filter structure of the present invention.

Figure 10 is a spectrum diagram of the third embodiment of the infrared bandpass filter structure of the present invention.

Figure 11 is a film structure diagram of the visible light reflectance experiment of the infrared bandpass filter structure of the present invention.

Figure 12 is a spectrum chart of the visible light reflectance experiment of the infrared bandpass filter structure of the present invention.

Figure 13 is the color coordinate range diagram of the visible light reflectance experiment of the infrared bandpass filter structure of the present invention.

Please refer to Figure 1, which shows that the infrared band-pass filter of the present invention includes a substrate 10, an infrared band-pass filter structure 20 and an anti-reflection (AR) layer 30, wherein: the substrate 10 is Glass, and at the same time has a first side surface and a second side surface located on the opposite side of the first side surface.

The infrared band-pass filter structure 20 is formed on the first side surface of the substrate 10, and is formed by alternately stacking a plurality of silicon aluminum hydride (SiAl: H) layers 21 and a plurality of lower refractive index layers 22, so that the infrared band-pass filter structure 20 has a passband that at least partially overlaps in the wavelength range of 800nm to 1600nm, the passband has a center wavelength, and the center wavelength is in magnitude when the incident angle changes from 0° to 30° The magnitude of shifts is less than 11nm (about 10.3~10.5nm). Moreover, the infrared bandpass filter structure 20 has a thickness of 3000-5500nm, a high OD value in the wavelength range of 350nm to 1600nm, a high transmittance in the wavelength range of 800nm to 1600nm, and the color coordinate position in the visible light range At Rx Coordinate 0.2~0.5 and Ry Coordinate 0.2~0.5, the reflectivity is lower than 20%. The refractive index of the plurality of silicon aluminum hydride layer 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 silicon aluminum oxide (SiAl: O ₂ ), silicon aluminum nitride (SiAl: N), silicon nitride (SiN), and silicon dioxide (SiO ₂ ), at least one of aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ), and mixtures thereof. Moreover, the refractive index of the plurality of lower refractive index layers 22 in the wavelength range of 800 nm to 1600 nm is less than 1.8, the extinction coefficient is less than 0.0005, and the extinction coefficient in the wavelength range of 350 nm to 700 nm is greater than 0.005.

The anti-reflection layer 30 is formed on the second side surface of the substrate 10, and is formed by stacking a plurality of high-refractive-index materials silicon aluminum hydride (SiAl: H) and a plurality of low-refractive-index materials. Containing aluminum silicon dioxide (SiAl: O2), aluminum silicon nitride (SiAl: N), silicon nitride (SiN), silicon dioxide (SiO2), aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), At least one of niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ) and mixtures thereof, and the thickness is 3000 nm to 6000 nm.

Please refer to Figure 2 which indicates that the sputtering process of the aluminum hydride silicon aluminum film layer 21 of the present invention is performed in a vacuum sputtering reactive coating system 40, which is mainly based on the use of doped aluminum components of 200 ppm to 1500 ppm Crystal sprayed silicon cylindrical target or single crystal The silicon cylindrical target is used as the sputtering target 45. The production process is (A) put the clean substrate 10 on the drum 41 with the coating surface facing outward; (B) make the drum 41 rotate in the coating chamber 42 at a uniform speed; C) When the vacuum degree is 10-3 to 10-4Pa, turn on the sputtering source 43 and ventilate argon gas. The argon gas is ionized to form plasma, which bombards the silicon aluminum target 45 and silicon aluminum material under the action of electric and magnetic fields. It is sputtered onto the substrate 10 to form a silicon-aluminum film; (D) With the rotation of the roller 200, the substrate 10 is taken to the reaction source (RF/ICP) area 44; (E) Hydrogen and oxygen are introduced into the reaction source area 44 It forms a plasma with argon gas, moves to the substrate 10 at high speed under the action of an electric field, and finally reacts with the silicon aluminum film on the substrate 10 to form a hydrogen-containing silicon aluminum hydride film 21. Among them, when preparing a high refractive index film, in the mixed gas filled in the reaction source area 44, by adjusting the ratio (flow rate) of hydrogen, the highest refractive index from 800nm to 1600nm can be prepared gradually changing from 3.1 to 4, and the extinction coefficient can be changed. Films less than 0.0005. When the gas filled in the reaction source area 44 is a mixed gas of oxygen and argon, a film with a refractive index of 350 nm to 1600 nm that gradually changes from 1.46 to 1.7 and an extinction coefficient of less than 0.0005 can be prepared.

Please refer to Figures 3 and 4, which is the first embodiment of the infrared bandpass filter structure of the present invention (850 bandpass filter), which is composed of a silicon aluminum hydride layer and a silicon aluminum dioxide layer stacked on each other for a total of 27 Layers are stacked, each with a thickness of about 3500nm. Wherein, the refractive index of the aluminum silicon hydride layer in the wavelength range of 800 nm to 1600 nm 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 350 nm to 700 nm is greater than 0.005. The refractive index of the aluminum silica layer in the wavelength range of 800 nm to 1600 nm is less than 1.8, and the extinction coefficient is less than 0.0005. The infrared band-pass filter structure formed by stacking has one of at least partially overlapping in the wavelength range of 800nm to 1600nm Pass band, the center wavelength of the pass band shifts less than 11 nm when the incident angle changes from 0° to 30°. When applied to a 3D imaging system, it can improve 3D image analysis capabilities.

Please refer to Figures 5 and 6, which is the first experiment (940 bandpass filter) of the second embodiment of the infrared bandpass filter structure of the present invention, which is derived from the silicon aluminum hydride layer and the silicon aluminum dioxide layer. A total of 31 layers are stacked, each with a thickness of about 4000nm. Wherein, the refractive index of the aluminum silicon hydride layer in the wavelength range of 800 nm to 1600 nm 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 350 nm to 700 nm is greater than 0.005. The refractive index of the aluminum silica layer in the wavelength range of 800 nm to 1600 nm is less than 1.8, and the extinction coefficient is less than 0.0005. The stacked infrared bandpass filter structure has a passband at least partially overlapping in the wavelength range of 800nm to 1600nm, and the center wavelength of the passband has an offset of less than 11nm when the incident angle changes from 0° to 30°. When applied to a 3D imaging system, it can improve 3D image analysis capabilities.

Please refer to Figures 7 and 8, which is the second experiment (940 bandpass lilter) of the second embodiment of the infrared bandpass filter structure of the present invention, which is mutually pushed by the silicon aluminum hydride layer and the silicon aluminum oxide layer. A total of 35 layers are stacked, and the thickness is about 4000~550nm. Wherein, the refractive index of the aluminum silicon hydride layer in the wavelength range of 800 nm to 1600 nm 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 350 nm to 700 nm is greater than 0.005. The refractive index of the aluminum silica layer in the wavelength range of 800 nm to 1600 nm 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 at least partially overlapping in the wavelength range of 800nm to 1600nm, and the center wavelength of the passband changes from 0° at the incident angle When the offset amplitude is less than 11nm at 30°, the slope of T90~T10% will be better than that of example one (the slope of experiment one is less than 8 and the slope of experiment two is less than 7), and the OD value of the same position will be better than that of example one.

Please refer to Figures 9 and 10, which are the third embodiment of the infrared bandpass filter structure of the present invention (1064 bandpass filter), which is composed of a silicon aluminum hydride layer and a silicon aluminum dioxide layer stacked on each other for a total of 33 The thickness of each layer is below 5000nm. Wherein, the refractive index of the aluminum silicon hydride layer in the wavelength range of 800 nm to 1600 nm 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 350 nm to 700 nm is greater than 0.005. The refractive index of the aluminum silica layer in the wavelength range of 800 nm to 1600 nm is less than 1.8, and the extinction coefficient is less than 0.0005. The infrared band-pass filter structure formed by stacking has a passband at least partially overlapping in the wavelength range of 800nm to 1600nm. The center wavelength of the passband has an offset of less than 2nm when the incident angle changes from 0° to 7°. When the incident angle of the passband in the wavelength range of 1000nm and 1120~1600 changes from 0° to 7°, OD>3.

Please refer to Figures 11 to 13, which is a visible light reflectance experiment of the infrared band-pass filter structure of the present invention. It is made up of 37 layers of aluminum silicon hydride and aluminum silicon dioxide. In the visible light range, the color coordinates are at Rx Coordinate 0.2~0.5 and Ry Coordinate 0.2~0.5, and the reflectivity is less than 20%.

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

1. The central wavelength of the passband of the infrared band filter structure 20 formed by alternately stacking the plurality of silicon aluminum hydride layers 21 and the plurality of lower refractive index layers 22 of the present invention When the incident angle is changed from 0° to 30°, there will be a small offset less than 11nm (about 10.3~10.5nm), so it is not easy to cause the problem of unrecognition or recognition failure when applied to a three-dimensional imaging system.

2. The aluminum-doped silicon aluminum target of the present invention can withstand more than twice the power output (about 10-20KW) than the conventional pure silicon target, so the coating time can be reduced by at least half, and the relative output at the same time can be increased by one The cost of resources including the production time of the whole plant, manpower, and electricity will also be reduced by half, greatly improving the competitive advantage.

3. The film layer of the present invention can be made into a smaller thickness due to the good ductility of the aluminum component. Therefore, when the film thickness is less when plating on a glass substrate, the internal stress is relatively small. The small internal stress can make The subsequent cutting process reduces the occurrence of corner chipping, so as to increase the yield of the cutting process, and relatively further achieve the purpose of reducing costs.

To sum up, because the present invention has the above advantages and practical value, and no similar products have been published in similar products, it has met the requirements of an invention patent application and it is a lawful application.

10‧‧‧Substrate

20‧‧‧Infrared bandpass filter structure

21‧‧‧Silica and aluminum layer

22‧‧‧Lower refractive index layer

30‧‧‧Anti-reflective layer

Claims (16)

An infrared band-pass filter structure is formed by alternately stacking a plurality of silicon aluminum hydride (SiAl: H) layers and a plurality of lower refractive index layers, the plurality of lower refractive index layers being an oxide, and the infrared band-pass filter structure has 800 nm The wavelength range to 1600nm at least partially overlaps a passband, the passband has a center wavelength, and the center wavelength shifts in magnitude when the incident angle changes from 0° to 30° ( shifts) The amplitude is less than 11nm. The infrared band-pass filter structure according to claim 1, wherein the thickness of the infrared band-pass filter structure is 3000-5500 nm. The infrared band-pass filtering structure according to claim 1, wherein the infrared band-pass filtering structure has a high OD value in the wavelength range of 350 nm to 1600 nm, and a high transmittance in the wavelength range of 800 nm to 1600 nm. The infrared band-pass filter structure described in claim 1, wherein the color coordinates of the infrared band-pass filter structure are at Rx Coordinate 0.2~0.5 and Ry Coordinate 0.2~0.5 in the visible light range, and the reflectivity is less than 20%. The infrared bandpass filter structure according to claim 1, wherein the refractive index of the complex aluminum silicon hydride layer in the wavelength range of 800nm to 1600nm is 3.1~3.6, and the extinction coefficient is 1.E-4~1.E-6, The extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The infrared bandpass filter structure according to claim 1, wherein the plurality of lower refractive index layers include silicon aluminum oxide (SiA: lO ₂ ), silicon aluminum nitride (SiAl: N), silicon nitride (SiN), At least one of silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ) and mixtures thereof One. The infrared bandpass filter structure according to claim 1, wherein the refractive index of the complex lower refractive index layer in the wavelength range of 800 nm to 1600 nm is less than 1.8, and the extinction coefficient is less than 0.0005. An infrared band-pass filter includes: a substrate having a first side surface and a second side surface opposite to the first side surface; an infrared band-pass filter structure formed on the first side surface of the substrate, It is formed by alternately stacking a plurality of silicon aluminum hydride (SiAl: H) layers and a plurality of lower refractive index layers. The plurality of lower refractive index layers are oxides. The infrared band-pass filter structure has a wavelength range of at least 800 nm to 1600 nm. A passband partially overlapping, the passband has a central wavelength, and the central wavelength shifts in magnitude less than 11nm when the incident angle is changed from 0° to 30°; and An anti-reflection (AR) layer is formed on the second side surface of the substrate. The infrared band pass filter according to claim 8, wherein the thickness of the infrared band pass filter structure is 3000-5500 nm. The infrared band-pass filter according to claim 8, wherein the infrared band-pass filter structure has a high OD value in the wavelength range of 350 nm to 1600 nm, and a high transmittance in the wavelength range of 800 nm to 1600 nm. The infrared band-pass filter according to claim 8, wherein the color coordinates of the infrared band-pass filter structure in the visible range are Rx Coordinate 0.2~0.5, Ry At Coordinate 0.2~0.5, the reflectivity is lower than 20%. The infrared bandpass filter according to claim 8, wherein the refractive index of the complex aluminum silicon hydride layer in the wavelength range of 800nm to 1600nm is 3.1~3.6, and the extinction coefficient is 1.E-4~1.E-6, The extinction coefficient in the wavelength range of 350nm to 700nm is greater than 0.005. The infrared bandpass filter according to claim 8, wherein the plurality of lower refractive index layers includes silicon aluminum oxide (SiAl: O ₂ ), silicon aluminum nitride (SiAl: N), silicon nitride (SiN), At least one of silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ) and mixtures thereof One. The infrared bandpass filter according to claim 8, wherein the refractive index of the plurality of lower refractive index layers 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 Greater than 0.005. The infrared bandpass filter according to claim 8, wherein the anti-reflection layer is formed by stacking a plurality of high-refractive-index materials of silicon aluminum hydride (SiAl: H) and a plurality of low-refractive-index materials, and the low-refractive-index material Contains aluminum silicon dioxide (SiAl: O2), silicon dioxide (SiO2), aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ) and at least one of its mixtures. The infrared bandpass filter according to claim 8, wherein the thickness of the anti-reflection layer is 3000 nm to 6000 nm.

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