Optical interference filter

Abstract

To improve the performance, manufacturability and / or reliability of an optical filter by reducing the complexity associated with forming a set of layers.SOLUTION: An optical interference filter includes a substrate, and a set of layers disposed on the substrate. The set of layers includes a first subset of layers, and a second subset of layers. Each layer of the first subset comprises an aluminum nitride (AlN) material. A stress of each layer of the first subset is between -1000 and 800 megapascals. The first subset of layers has a first refractive index with a first value. Each layer of the second subset comprises at least one other material. The second subset of layers has a second refractive index with a second value that is different than the first value. The optical interference filter has an effective refractive index greater than or equal to 95% of the highest value of the first and second values.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention relates to an optical interference filter. [Background technology]

[0002] Optical devices can be used to capture information about light. For example, an optical device can capture information about a set of wavelengths associated with light. An optical device may include a set of sensor elements (e.g., optical sensors, spectral sensors, and / or image sensors) that capture information. For example, a sensor element array can be used to capture information about multiple wavelengths. The sensor element array can be associated with an optical filter. The optical filter may include a passband related to light in a first wavelength range passing through the sensor element array. The optical filter may be associated with preventing light in a second wavelength range from passing through the sensor element array. [Overview of the Initiative] [Means for solving the problem]

[0003] In some implementations, the optical interference filter comprises a substrate and a set of layers disposed on the substrate, the set of layers having a first subset of layers and a second subset of layers, each first subset of layers containing aluminum nitride (AlN) material, each first subset of layers having a stress of -1000 to 800 megapascals, each first subset of layers having a first refractive index having a first value, each second subset of layers containing at least one other material, each second subset of layers having a second refractive index having a second value different from the first value, and the optical interference filter having an effective refractive index of 95% or more of the highest of the first and second values.

[0004] In some implementations, the optical interference filter comprises a set of layers, each set of layers having a first subset of layers and a second subset of layers, where each first subset of layers contains AlN material and has a first refractive index having a first value, and each second subset of layers contains silicon hydride-helium (Si:H-He) material and has a second refractive index having a second value greater than the first value, and the optical interference filter has an effective refractive index of 95% or more of the second value.

[0005] In some embodiments, the method includes the steps of: supplying an inert gas to a chamber, the inert gas comprising at least one of argon (Ar) or helium (He); supplying nitrogen gas (N2) to the chamber; and sputtering an aluminum (Al) target based on the supply of the inert gas and N2 gas to form a first set of layers comprising aluminum nitride (AlN) on a substrate, wherein the first set of layers is formed on the substrate alternately with a second set of layers, the second set of layers comprising silicon hydride-helium (Si:H-He), and the layer array has an effective refractive index of 3.7 or greater. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic diagram of an exemplary implementation described herein. [Figure 2] This is an illustrative diagram of an exemplary optical filter described herein. [Figure 3] This is an illustrative diagram of an example of a sputter deposition system for manufacturing optical filters as described herein. [Figure 4A] This is a diagram of an exemplary plot showing the stress of an AlN layer formed using the sputtering process described herein. [Figure 4B] This is a diagram of an exemplary plot showing the stress of an AlN layer formed using the sputtering process described herein. [Figure 5] This is a diagram of exemplary plots of the absorption coefficient and refractive index of a set of AlN layers formed using the sputtering process described herein. [Figure 6] This is a diagram of an exemplary plot illustrating the transmission performance of the optical filters described herein. [Figure 7A] These are the optical and physical properties of the exemplary implementations described herein. [Figure 7B] These are the optical and physical properties of the exemplary implementations described herein. [Figure 7C] These are the optical and physical properties of the exemplary implementations described herein. [Figure 8A] These are the optical and physical properties of the exemplary implementations described herein. [Figure 8B] These are the optical and physical properties of the exemplary implementations described herein. [Figure 8C] These are the optical and physical properties of the exemplary implementations described herein. [Modes for carrying out the invention]

[0007] The following detailed description of exemplary implementations refers to the accompanying drawings. Identical reference numerals in different drawings may indicate the same or similar elements. A spectrometer is used as an example in the following description. However, the techniques, principles, procedures, and methods described herein may be used with any other sensors, including but not limited to other optical sensors and spectral sensors.

[0008] Optical filters can be manufactured by forming one or more layers on a substrate. For example, conventional optical filters can allow a threshold percentage (e.g., at least 65% of the light) of light related to a specific spectral range (e.g., the 800-1600 nanometer (nm) spectral range) to pass through by comprising alternating layers of at least a first material, a second material, and a third material (e.g., alternating layers of silicon hydride (Si:H), silicon dioxide (SiO2), and tantalum pentoxide (Ta2O5) materials). However, forming alternating layers of at least three materials is difficult and can lead to the formation of low-quality layers, thus introducing defects or allowing defects to propagate through conventional optical filters. This can reduce the performance, manufacturability, and / or reliability of conventional optical filters.

[0009] Furthermore, in many cases, the stress in one or more layers of a conventional optical filter is compressible (e.g., the stress in a layer is less than 0 megapascals (MPa)), and therefore the stress in one or more layers (e.g., net stress) is compressible. As a result, this compressibility causes the conventional optical filter to bend (e.g., flex). This leads to coating runoff in one or more layers, affecting the performance of the conventional optical filter. This also makes the conventional optical filter more fragile (e.g., compared to a flat optical filter) and / or makes it difficult to transport, handle, and / or use the conventional optical filter.

[0010] Furthermore, the filtering performance of conventional optical filters can degrade when the angle of incidence (AOI) of light heading towards the optical filter changes from a set angle of incidence (e.g., 0 degrees (normal), 30 degrees, 45 degrees, etc.) to a threshold angle of incidence (e.g., a deviation of approximately 10 degrees from the set angle of incidence, a deviation of 20 degrees from the set angle of incidence, and / or a deviation greater than 30 degrees from the set angle of incidence). For example, conventional optical filters may shift toward lower wavelengths as the angle of incidence increases. Thus, conventional optical filters may allow unwanted or undesirable light to pass through, which can affect the detection accuracy of optical sensors that receive the passed light.

[0011] The angular shift may be related to the effective refractive index of an optical filter (e.g., a bandpass filter). For example, a higher effective refractive index correlates with a lower angular shift. The effective refractive index can be calculated from the refractive indices of the constituent materials of the optical filter. For example, the effective refractive index of an optical filter having a mirror formed by alternating high refractive index constituent material layers and low refractive index constituent material layers can be calculated, at least in part, based on a set of equations of the following form.

Number

Number

Number

number

[0012] The above equation shows that as the effective refractive index increases, the angular shift of the filter decreases. However, the limit of the filter's effective refractive index is less than the refractive index of the highest refractive index material in the filter (Equation (3)).

[0013] Several implementations described herein provide an optical filter comprising a set of layers arranged on a substrate. The set of layers may comprise alternating arrangements of a first subset of layers containing aluminum nitride (AlN) material and a second subset of layers containing at least one other material (e.g., at least one material other than AlN), such as silicon hydride-helium (Si:H-He) material. In some implementations, the optical filter allows a threshold percentage (e.g., at least 90% of the light) of light related to a specific spectral range (e.g., the spectral range of 800–1600 nm) to pass through. In this way, the optical filter provides improved transmission performance compared to conventional optical filters. Furthermore, the optical filter comprises only two alternating layers, thereby reducing the complexity associated with forming the set of layers. This reduces the possibility of forming low-quality layers and, therefore, the possibility of defects being introduced into or propagating through the optical filter. Thus, the performance, manufacturability, and / or reliability of the optical filter are improved compared to conventional optical filters.

[0014] In some implementations, the stress of the first subset of layers containing AlN material can be set to -1000 to 800 MPa. Therefore, in some implementations, if the stress of the second subset of layers is compressive, the stress of the AlN material can be configured to be tensile (e.g., 0 MPa or higher), or vice versa. In this way, the amount of bending caused by the set of layers arranged on the substrate can be minimized (for example, by balancing the stress of the compression layer with the stress of the tensile layer of the optical filter). For example, one of the first subset of layers and the second subset of layers may contain a tensile material, and the other of the first subset of layers and the second subset of layers may contain a compressive material, thereby allowing the stress of the set of layers to be approximately 0 MPa (e.g., within tolerance). This minimizes the amount of bending of the optical filter, reduces coating runoff, and thereby improves the performance of the optical filter (for example, compared to conventional optical filters that bend). Furthermore, this improves the durability of the optical filter and / or makes it easier to transport, handle, and / or use the optical filter compared to conventional optical filters that may bend. In certain cases, such as when the diameter of the optical filter is about 200 millimeters (mm), several implementations described herein can reduce the amount of bending of the optical filter to, in particular, less than 10 mm, less than 5 mm, and / or less than 0.1 mm. In another case, when the optical filter is configured to allow light related to wavelength λ to pass through, several implementations described herein can reduce the amount of bending of the optical filter to, in particular, less than λ / 4, less than λ / 10, and / or less than λ / 100.

[0015] Furthermore, some implementations described herein provide low-angle shift optical filters in which the effective refractive index is greater than 95% of the refractive index of the highest refractive index material in the low-angle shift optical filter. For example, a low-angle shift optical filter may have an effective refractive index of the following form:

number

[0016] Additionally, or alternatively, a low-angle shift optical filter can have an effective refractive index greater than 100%, 110%, or 120% of the refractive index of the highest refractive index material within the low-angle shift optical filter. In this way, the low-angle shift optical filter reduces the amount of unwanted or undesirable light passing through it, thereby improving the detection accuracy of an optical sensor that receives light passing through the low-angle shift optical filter.

[0017] Figure 1 is a schematic diagram of an exemplary implementation 100 described herein. As shown in Figure 1, the exemplary implementation 100 includes a sensor system 110. The sensor system 110 may be part of an optical system and may supply an electrical output corresponding to a sensor determination. The sensor system 110 includes an optical filter structure 120 including an optical filter 130, and an optical sensor 140. For example, the optical filter structure 120 may include an optical filter 130 that performs a passband filtering function. In another example, the optical filter 130 may be aligned with the sensor element array of the optical sensor 140.

[0018] While some embodiments described herein may relate to optical filters within a sensor system, the embodiments described herein may be used in other types of systems, outside of a sensor system, or in other configurations.

[0019] As shown in Figure 1 and further indicated by reference numeral 150, the input optical signal is directed to the optical filter structure 120 at one or more incident angles θ. For example, input optical signals 150-1 and 150-2 can be directed to the optical filter 120 at incident angles θ0 (e.g., a set incident angle) and θ. The input optical signal may include, but is not limited to, light related to a specific spectral range (e.g., a spectral range centered around approximately 900 nm, such as the 800 nm to 1000 nm spectral range; the 800 nm to 1600 nm spectral range; the 800 nm to 1100 nm spectral range; the 1400 nm to 1600 nm spectral range, e.g., a peak wavelength of 1550 nm; the 500 nm to 5500 nm spectral range; or another spectral range). For example, the optical transmitter may direct light to the optical sensor 140 so that the optical sensor 140 can perform light measurements. In another example, the optical transmitter may direct light from a different spectral range for other functions, such as inspection, detection, or communication.

[0020] As shown in Figure 1 and further indicated by reference numeral 160, a first portion of the optical signal having a first spectral range does not pass through the optical filter 130 and the optical filter structure 120. For example, the dielectric filter laminate of dielectric thin film layers may include a high refractive index material layer and a low refractive index material layer of the optical filter 130, and this dielectric filter laminate can reflect or absorb the first portion of the light in a first direction. In this case, the first portion of the light may be a threshold portion of the light incident on the optical filter 130 that is not included in the passband of the optical filter 130, and may be, for example, more than 95% of the light that is not in a specific spectral range centered around approximately 900 nm. As indicated by reference numeral 170, a second portion of the optical signal passes through the optical filter 130 and the optical filter structure 120. For example, the optical filter 130 can allow a second portion of the light having a second spectral range to pass in a second direction toward the optical sensor 140. In this case, the second portion of the light may be the threshold portion of the light incident on the optical filter 130 that is included in the bandpass of the optical filter 130, and may be, for example, more than 50% of the incident light that is in a spectral range centered around approximately 900 nm. The second portion of the light can pass through the optical filter 130 with a threshold angular shift less than that, as will be described in more detail herein.

[0021] As further shown in Figure 1, based on the fact that a second portion of the optical signal passes through the optical sensor 140, the optical sensor 140 can supply an output electrical signal 180 for the sensor system 110, for use, among other things, for imaging, ambient light detection, object presence detection, performing measurements, or facilitating communication. In some implementations, alternative arrangements of the optical filter 130 and the optical sensor 140 can be utilized. For example, instead of the optical filter 130 passing the second portion of the optical signal colinearly with the input optical signal, the second portion of the optical signal may be directed in a different direction toward the optical sensor 140 located elsewhere.

[0022] As described above, Figure 1 is presented as an example. Other examples may differ from those described in relation to Figure 1.

[0023] Figure 2 shows an exemplary optical filter 200. In some implementations, the optical filter 200 may be an optical interference filter and / or, in particular, comprise at least one of the following: spectral filters, multispectral filters, bandpass filters, blocking filters, long-wave pass filters, short-wave pass filters, dichroic filters, linear variable filters, circular variable filters, Fabry-Perot filters, Bayer filters, plasmon filters, photonic crystal filters, nanostructured or metamaterial filters, absorption filters, beam splitters, polarizing beam splitters, notch filters, anti-reflective filters, reflective materials, or mirrors. Figure 2 shows an exemplary stack of the optical filter 200. As further shown in Figure 2, the optical filter 200 comprises a substrate 210 and a set of layers 220.

[0024] The substrate 210 may include a glass substrate, a polymer substrate, a polycarbonate substrate, a metal substrate, a silicon (Si) substrate, a germanium (Ge) substrate, or an active element wafer (for example, in particular, comprising a photodiode (PD), a PD array, an avalanche photodiode (APD), an APD array, a charge-coupled device (CCD) sensor, and / or a complementary metal-oxide-semiconductor (CMOS) sensor). In some mounting configurations, the thickness of the substrate 210 may be 20 microns (μm), 50 μm, and / or 500 μm or more. Additionally or alternatively, the thickness of the substrate may be below a certain thickness threshold. The certain thickness threshold may be, for example, 5 millimeters (mm) or less.

[0025] The set of layers 220 (e.g., a set of optical filter layers) may be arranged on the substrate 210 (e.g., directly on it), or may include one or more subsets of layers. For example, the set of layers 220 may include a first subset of layers 230 (e.g., a first subset of layers 230-1 to 230-(N+1)(N≧1)) (also referred to herein as layer A) and a second subset of layers 240 (e.g., a second subset of layers 240-1 to 240-N) (also referred to herein as layer B). In some embodiments, the first subset of layers 230 and the second subset of layers 240 are (AB) m (m≧1) order, (AB) m -A in order, (BA) m The order is B-(BA) m They may be arranged in a specific order (e.g., alternating layer order), such as the order of (A) or another order. For example, as shown in Figure 2, the first subset of layer 230 and the second subset of layer 240 are (A) N The layers are arranged in the order -A, with layer A (e.g., layer 230-1) arranged on the surface (e.g., top surface) of the optical filter 200, and layer A (e.g., layer 230-(N+1)) arranged on the surface (e.g., top surface) of the substrate 210.

[0026] In some implementation configurations, the set of layers 220 may be arranged on one side (e.g., the top surface) of the substrate 210 (e.g., as shown in Figure 2). Alternatively, the first portion of the set of layers 220 may be arranged on a first surface (e.g., the top surface) of the substrate 210, and the second portion of the set of layers 220 may be arranged on a second surface (e.g., the bottom surface) of the substrate 210. For example, the first portion of the first subset 230 of layers and the first portion of the second subset 240 of layers may be arranged on the first surface of the substrate 210 in a first specific order, and the second portion of the first subset 230 of layers and the second portion of the second subset 240 of layers may be arranged on the second surface of the substrate 210 in a second specific order.

[0027] In some implementations, the optical filter 200 may include one or more additional layers, such as one or more protective layers, one or more capping layers (e.g., providing environmental protection to the set of layers 220), and / or one or more layers that provide one or more other filtering functions (e.g., blockers or anti-reflective coatings, among other things). For example, in a single-sided configuration, an additional layer (e.g., a capping layer) such as a dielectric layer (e.g., an oxide material such as silicon dioxide (SiO2) material, zirconium dioxide (ZrO2) material, and / or yttrium oxide (Y2O3) material; a nitride material such as silicon nitride (Si3N4) material, titanium nitride (TiN) material, and / or zirconium nitride (ZrN) material; and / or another material that provides environmental protection) may be placed on the surface (e.g., the top surface) of the set of layers 220. As another example, in a double-sided configuration, the first additional layer may be placed on the surface (e.g., top surface) of the first portion of the set of layers 220, and the second additional layer may be placed on the surface (e.g., bottom surface) of the second portion of the set of layers 220.

[0028] The first subset 230 of the layers may include aluminum nitride (AlN) material. For example, each layer 230 of the first subset 230 of the layers may include AlN material. The second subset 240 of the layers may, in particular, include silicon (Si) material, silicon and hydrogen (SiH) material, silicon hydride (Si:H) material, silicon hydride-helium (Si:H-He) material, amorphous silicon (a-Si) material, silicon nitride (SiN) material, germanium (Ge) material, germanium hydride (Ge:H) material, silicon germanium (SiGe) material, silicon hydride germanium (SiGe:H) material, silicon carbide (SiC) material, silicon carbide hydride (SiC:H) material, silicon dioxide (SiO2) material, tantalum pentoxide (Ta2O5) material, niobium pentoxide (Nb2O5) material, titanium niobium oxide (NbTiO2) x ) Materials, niobium tantalum pentoxide (Nb 2-x Ta xThe material may also contain at least one other material (for example, at least one other material other than AlN material), such as O5 material, titanium dioxide (TiO2) material, aluminum oxide (Al2O3) material, zirconium oxide (ZrO2) material, yttrium oxide (Y2O3) material, or hafnium oxide (HfO2) material. For example, each layer 240 of the second subset 240 of the layers may contain at least one other material.

[0029] In some implementations, the stress (e.g., net stress) of the first subset 230 of the layers may be -1000 to 800 MPa (e.g., -1000 MPa or more and 800 MPa or less). Additionally or alternatively, the stress of each layer 230 in the first subset 230 of the layers may be -1000 to 800 MPa. That is, the stress of a particular layer 230 in the first subset 230 of the layers may be -1000 to 800 MPa, and the stress of another particular layer 230 in the first subset 230 of the layers may be -1000 to 800 MPa. The stress of a particular layer 230 may be the same as or different from the stress of another particular layer 230. For example, the stress of a particular layer 230 may be tensile stress (e.g., 0 MPa or more), and the stress of another particular layer 230 may be compressive stress (e.g., less than 0 MPa), or vice versa.

[0030] In some implementations, the stress (e.g., net stress) of the layer set 220 can be made approximately zero (0) MPa (e.g., within tolerance, with a tolerance of 5 MPa or less). Thus, at least one of the first subset 230 and the second subset 240 of the layer may comprise a tensile material, and the other of the first subset 230 and the second subset 240 of the layer may comprise a compressive material (e.g., to make the stress of the layer set 220 approximately 0 MPa). For example, the first subset 230 of the layer may include a tensile material, and the second subset 240 of the layer may include a compressive material, or vice versa. As another example, the first subset 230 of the layer may include a tensile AlN material, and the second subset 240 of the layer may include at least one other compressible material (e.g., at least one of compressive Si material, compressive Si:H material, compressive Si:H-He material, or compressive a-Si material). In some implementations, the stress (e.g., net stress) of layer set 220 may be approximately equal to a specific amount of stress (e.g., within the tolerance range, with a tolerance of 5 MPa or less). For example, the first subset 230 of layer and the second subset 240 of layer may include specific configurations of compression and / or tension materials such that the stress of layer set 230 is equal to a specific amount of stress, such as 350 MPa.

[0031] In some implementations, each layer of the set of layers 220 may be associated with a specific thickness. For example, a layer consisting of a first subset 230 or a second subset 240 may have a thickness of 5 to 2000 nm. In some implementations, the first subset 230 or the second subset 240 may be associated with multiple thicknesses, such as a first thickness for the first subset 230 and a second thickness for the second subset 240, a first thickness for the first part of the first subset 230 and a second thickness for the second part of the first subset 230, or a first thickness for the first part of the second subset 240 and a second thickness for the second part of the second subset 240. Thus, the thickness of the layers and / or the amount of layers can be selected based on a set of desired optical properties of the optical filter 200, such as a desired passband, desired transmittance, and / or other optical properties. For example, the thickness and / or amount of the layers may be selected so that the optical filter 200 can be used for a spectral range of 800-1000 nm (e.g., with a center wavelength of approximately 900 nm), a spectral range of 800 nm-1600 nm, a spectral range of 800 nm-1100 nm, a spectral range of 1400 nm-1600 nm (e.g., with a peak wavelength of 1550 nm), a spectral range of 500-5500 nm, or another spectral range (e.g., to allow light related to these spectral ranges to pass through).

[0032] In some implementations, the set of layers 230 may be configured to allow a threshold percentage of light related to a specific spectral range to pass through. For example, the set of layers 230 may be configured to allow a threshold percentage of light related to the 800-1000 nm spectral range (e.g., with a central wavelength of approximately 900 nm) to pass through. The threshold range may be, for example, 85% or more. In some implementations, the absorption coefficient of the first subset 230 of layers may be less than 0.001 for light having wavelengths of 500 nm to 5500 nm.

[0033] In some implementations, the first subset 230 of the layer may have a first refractive index having a first value, and the second subset 240 of the layer may have a second refractive index having a second value (for example, different from the first value). For example, the refractive index of the first subset 230 of the layer may be 1.9 to 2.2 for light having a wavelength of 500 to 5500 nm, and / or the refractive index of the second subset 240 of the layer may be 3.5 to 3.9 for light having a wavelength of 500 to 5500 nm. In some implementations, the optical filter 200 may have an effective refractive index of 95% or more of the highest of the first and second values. For example, if the first subset of layer 230 and the second subset of layer 240 are arranged in a specific layer order (e.g., a layer order in which high refractive index and low refractive index layers alternate), the first subset of layer 230 and the second subset of layer 240 may be sized to achieve an effective refractive index of, for example, 95% or more of the highest of the first and second values. In some implementations, the optical filter 200 may have an effective refractive index of 100% or more of the highest of the first and second values ​​(e.g., up to 110%, 120%, 130%, 140%, or 150% of the highest value). Therefore, for example, if the refractive index of the second subset of layer 240 is 3.5 to 3.9 and is greater than the refractive index of the first subset of layer 230, the effective refractive index may be 3.7, 4.0, 4.5, 5.0, and / or 5.5 or higher.

[0034] In some implementation configurations, the set of layers 230 may be formed using a sputtering process. For example, the set of layers 230 may be formed using a magnetron sputtering process (e.g., a pulsed magnetron sputtering process), thereby sputtering a first subset of layers 230 and / or a second subset of layers 240 onto the substrate 210 (e.g., in an alternating layer order). The optical filter 200 may be manufactured in this manner. Further details relating to the manufacture of the optical filter 200 are described herein in reference to Figure 3.

[0035] As described above, Figure 2 is presented as an example. Other examples may differ from those described in relation to Figure 2.

[0036] Figure 3 shows an example 300 of a sputter deposition system for manufacturing an optical filter (e.g., optical filter 200) as described herein. The sputter deposition system can be used to enable sputtering processes such as a magnetron sputtering process.

[0037] As shown in Figure 3, Example 300 includes a vacuum chamber 310, a substrate 320 (corresponding, for example, to the substrate 210 described herein in relation to Figure 2), a cathode 330, a target 331, a cathode power supply 340, an anode 350, a plasma activation source (PAS) 360, and a PAS power supply 370. The target 331 may include an aluminum (Al) material. The PAS power supply 370 may be used to supply power to the PAS 360 and may include a radio frequency (RF) power supply. The cathode power supply 340 may be used to supply power to the cathode 330 and may include a pulsed direct current (DC) power supply.

[0038] With respect to Figure 3, aluminum nitride (AlN) can be deposited on the substrate 320 as at least one layer by sputtering the target 331 in the presence of nitrogen gas (N2) and / or an inert gas (e.g., including argon (Ar), helium (He), and / or neon (Ne)). For example, N2 gas and an inert gas can be supplied to the vacuum chamber 310, respectively, and the target 331 can be sputtered to form a first set of layers containing AlN on the substrate 320 (e.g., as further described herein). In some configurations, an array of layers may be formed on the substrate by alternating the first set of layers with a second set of layers containing at least one other material, such as a second set of layers containing Si, Si:H, Si:H-He, a-Si, and / or (e.g., with respect to the second subset 240 of layers described herein with respect to Figure 2). A second set of layers may be formed on the substrate (for example, in a manner similar to those further described herein) by supplying another gas (e.g., hydrogen gas (H2)) and an inert gas (e.g., including Ar, He, and / or Ne) to the vacuum chamber 310 and sputtering another target (e.g., a silicon target) to form the second set of layers (e.g., in this example, including Si:H or Si:H-He).

[0039] In some implementations, the layer arrangement may be in a specific layer order (e.g., alternating high-refractive-index and low-refractive-index layers) such that the effective refractive index of the layer formation is 95% or more of the value of the highest refractive index material (e.g., up to 110%, 120%, 130%, 140%, or 150%). Therefore, for example, the effective refractive index may be 3.7, 4.0, 4.5, 5.0, and / or 5.5 or higher (e.g., if the refractive index of the second subset of layers is 3.5 to 3.9 and is greater than the refractive index of the first subset of layers).

[0040] To form the AlN layer, an inert gas can be supplied into the vacuum chamber 310 through the anode 350 and / or PAS 360. N2 gas is introduced into the vacuum chamber 310 through the PAS 360, which activates the N2 gas. Additionally or alternatively, the N2 gas can be activated by the cathode 330 (for example, in this case the N2 gas can be introduced from another part of the vacuum chamber 310), or by the anode 350 (for example, in this case the N2 gas can be introduced into the vacuum chamber 310 by the anode 350). The PAS 360 may be located near the threshold of the cathode 330, thereby allowing the plasma from the PAS 360 to be stacked with the plasma from the cathode 330. By using the PAS 360, AlN can be deposited at a relatively high deposition rate. In some implementations, AlN can be deposited at deposition rates of approximately 0.05 nm / s to 2.0 nm / s, approximately 0.5 nm / s to 1.2 nm / s, approximately 0.8 nm / s, or similar rates.

[0041] In some implementations, the stress of the AlN layer (e.g., after formation) can be adjusted based on controlling the composition of the inert gas and / or the amount of inert gas supplied to the vacuum chamber 310. For example, if the inert gas contains Ar, the amount of Ar in the inert gas and / or the amount of inert gas supplied to the vacuum chamber 310 can be controlled so that the stress of the AlN layer is between -230 and 800 MPa. Additionally or alternatively, if the inert gas contains Ar, the amount of Ar in the inert gas and / or the amount of inert gas supplied to the vacuum chamber 310 can be controlled so that the stress (e.g., net stress) of the first set of layers containing AlN is between -230 and 800 MPa. As another example, if the inert gas contains He and / or Ne, the amount of He and / or Ne in the inert gas, and / or the amount of inert gas supplied to the vacuum chamber 310 can be controlled so that the stress of the AlN layer is between -1000 and 150 MPa. Additionally, or alternatively, if the inert gas contains He and / or Ne, the amount of He and / or Ne in the inert gas, and / or the amount of inert gas supplied to the vacuum chamber 310, can be controlled so that the stress of the first set of layers containing AlN is between -1000 and 150 MPa.

[0042] While this specification describes a sputtering process, other geometries and implementation configurations are possible with respect to specific geometries and implementation configurations. For example, the N2 gas may be injected from a different direction and / or, in particular, from another gas manifold located near the threshold of cathode 330. While this specification describes different configurations of components, different relative concentrations of AlN can also be achieved using different materials, different manufacturing processes, etc.

[0043] As described above, Figure 3 is presented as an example. Other examples may differ from those described in relation to Figure 3.

[0044] Figures 4A and 4B are illustrative plots of 400 showing the stresses of AlN layers formed using the sputtering process described herein (e.g., the magnetron sputtering process). As shown in Figure 4A, the stress of the AlN layer can be set to -230 to 650 MPa when an inert gas containing Ar is supplied at a flow rate of 120 to 370 standard cubic centimeters / min (sccm) (e.g., to the vacuum chamber 310 of the sputtering deposition system described herein with respect to Figure 3). As shown in Figure 4B, the stress of the AlN layer can be set to -950 to 175 MPa when an inert gas containing He is supplied at a flow rate of 0 to 500 sccm (e.g., to the vacuum chamber 310 of the sputtering deposition system described herein with respect to Figure 3). In some implementations, an inert gas containing Ar is also supplied at a flow rate of 120 to 370 sccm (e.g., to the vacuum chamber 310 of the sputtering deposition system described herein with respect to Figure 3).

[0045] As mentioned above, Figures 4A and 4B are presented as examples. Other examples may differ from those described for Figures 4A and 4B.

[0046] Figure 5 is an exemplary plot of the absorption coefficient (k) and refractive index (r) of a set of AlN layers formed using the sputtering process described herein (e.g., magnetron sputtering process). As shown in Figure 5, the absorption coefficient can be less than 0.001 for light having wavelengths of 500–2000 nm. As further shown in Figure 5, the refractive index can be less than 2.2 for light having wavelengths of 500–2000 nm.

[0047] As described above, Figure 5 is presented as an example. Other embodiments may differ from those described with respect to Figure 5.

[0048] Figure 6 is a diagram of an exemplary plot 600 showing the transmission performance of an optical filter described herein (e.g., optical filter 200). The optical filter comprises a set of layers (e.g., set of layers 220) comprising a first subset of layers containing AlN material (e.g., first subset of layers 230) and a second subset of layers containing Si:H material (e.g., second subset of layers 240). As shown in Figure 6, the optical filter can transmit more than about 85% (peak of about 92%) of light having wavelengths of 920–960 nm. In contrast, an alternative optical filter comprising a set of layers having a first subset of layers containing Ta2O5 material and a second subset of layers containing Si:H material can transmit more than about 60% (peak of about 67%) of light having wavelengths of 920–960 nm. Therefore, the optical filter described herein has improved transmission performance compared to the alternative optical filter in the 920–960 nm spectral range.

[0049] As described above, Figure 6 is presented as an example. Other examples may differ from those described in relation to Figure 6.

[0050] Figures 7A to 7C are Tables 700 / 710 / 720 showing the optical and physical properties of exemplary implementations described herein.

[0051] As shown in Figure 7A, Figure 700 shows the angular shift performance of an optical filter (e.g., optical filter 200 described herein). The angular shift at the center wavelength of an optical interference filter can be less than 1.0% of the center wavelength when the incident angle (shown as θ in Figure 7A) is between 0 and 30 degrees. For example, if the optical filter is set to a center wavelength of 940 nanometers (nm), the optical filter may have an angular shift of less than 9.4 nm at an incident angle of up to 30 degrees. In some implementations, the optical filter may have an angular shift of less than 7.0 nm at an incident angle of up to 30 degrees. In this case, the optical filter can achieve an effective refractive index of, for example, 3.7, 4.0, 4.5, 5.0, and / or 5.5 or higher. In some implementations, the optical filter can achieve transmittances at the center wavelength that exceed transmittance thresholds such as greater than 80%, greater than 85%, greater than 90%, and / or greater than 95% (e.g., peak transmittance of the optical filter when the incident angle is between 0 and 30 degrees). Furthermore, optical filters can achieve ripple of less than + / -10%, less than + / -5%, or less than + / -1%, where ripple refers to the deviation of transmittance across the passband when the incident angle is between 0 and 30 degrees.

[0052] As shown in Figures 7B and 7C, Figures 710 and 720 illustrate exemplary lamination and layer thickness examples of optical filters. In this case, the optical filter is manufactured by alternately stacking layers containing AlN material (e.g., having a refractive index of 1.9 to 2.2 for light with wavelengths of 500 to 5500 nm) and layers containing Si:H-He material (e.g., having a refractive index of 3.5 to 3.9 for light with wavelengths of 500 to 5500 nm). The optical filter includes one or two “thick layers” that are greater than a threshold thickness (e.g., a thickness that is more than 200% thicker than the next thickest layer of one or more layers, and less than 500% thicker than the next thickest layer). In some implementations, the optical filter may include two thick layers, and these thick layers may be offset from each other by 10% to 25%. For example, the thickness of the smaller of the two thick layers may be 10% to 25% less than the thickness of the larger of the two thick layers.

[0053] As mentioned above, Figures 7A to 7C are presented as mere examples. Other examples may differ from those described in relation to Figures 7A to 7C.

[0054] Figures 8A to 8C are Tables 800 / 810 / 820 showing the optical and physical properties of exemplary implementations described herein.

[0055] As shown in Figure 8A, Figure 800 shows the angular shift performance of an optical filter (e.g., optical filter 200 described herein). The angular shift at the center wavelength of an optical interference filter can be less than 1.0% of the center wavelength when the incident angle (shown as θ in Figure 8A) is between 0 and 30 degrees. For example, if the optical filter is set to a center wavelength of 940 nanometers (nm), the optical filter can have an angular shift of less than 9.4 nm at an incident angle of up to 30 degrees. In some implementations, the optical filter can have an angular shift of less than 7.0 nm at an incident angle of up to 30 degrees. In this case, the optical filter can achieve an effective refractive index of, for example, 3.7, 4.0, 4.5, 5.0, and / or 5.5 or higher. In some implementations, the optical filter can achieve transmittances at the center wavelength that exceed transmittance thresholds such as greater than 80%, greater than 85%, greater than 90%, and / or greater than 95% (e.g., peak transmittance of the optical filter when the incident angle is between 0 and 30 degrees). Furthermore, optical filters can achieve ripple of less than + / -10%, less than + / -5%, or less than + / -1%, where ripple represents the deviation of transmittance across the passband when the incident angle is between 0 and 30 degrees.

[0056] As shown in Figures 8B and 8C, Figures 810 and 820 show examples of optical filter lamination and layer thicknesses. In this case, the optical filter is manufactured by alternately stacking layers containing AlN material (e.g., having a refractive index of 1.9 to 2.2 for light with wavelengths of 500 to 5500 nm) and layers containing Si:H-He material (e.g., having a refractive index of 3.5 to 3.9 for light with wavelengths of 500 to 5500 nm). The optical filter may also include an additional layer containing SiO2 material (e.g., a capping layer as described herein).

[0057] As mentioned above, Figures 8A-8C are presented as mere examples. Other examples may differ from those described with respect to Figures 8A-8C.

[0058] The foregoing disclosures are illustrative and explanatory, but are not intended to be exhaustive or to limit implementations to the exact forms disclosed. Modifications and variations may be made in light of the foregoing disclosures or derived from the practice of the implementations.

[0059] As used herein, the term “component” is intended to be broadly interpreted as hardware, firmware, or a combination of hardware and software. It will be apparent that the systems and / or methods described herein may be implemented in different forms of hardware, firmware, and / or combinations of hardware and software. The actual dedicated control hardware or software code used to implement these systems and / or methods is not limited to the implementation form. Accordingly, the operation and behavior of the systems and / or methods are described herein without reference to specific software code, and it is understood that software and hardware may be used to implement the systems and / or methods based on the descriptions herein.

[0060] As used herein, "meeting a threshold" may, depending on the context, refer to values ​​greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, or not equal to the threshold.

[0061] While specific combinations of features are described in the claims and / or disclosed herein, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features can be combined in ways not specifically described in the claims and / or disclosed herein. Each dependent claim listed below depends directly on only one claim, but the disclosure of various implementations includes each dependent claim combined with all other claims in the set of claims. As used herein, the phrase “at least one of” the list of items refers to any combination of those items, including a single element. For example, “at least one of a, b, or c” is intended to include any combination of a, b, c, ab, ac, bc, and abc, as well as any multiples of the same item.

[0062] Any element, action, or command used herein should not be construed as important or essential unless expressly stated otherwise. Furthermore, as used herein, the articles “a” and “an” are intended to include one or more items, and as used herein, the article “the” is intended to include one or more items referred to in relation to the article “the,” and may be used interchangeably with “the one or more.” Additionally, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items), and may be used interchangeably with “one or more.” Furthermore, as used herein, terms such as “have, has, having” are intended to be open-ended terms. Finally, as used herein, the phrase “based on” is intended to mean “based, at least in part, on” unless otherwise specified. Furthermore, as used herein, the term "or" is intended to be inclusive when used consecutively and may be used interchangeably with "and / or" unless expressly otherwise specified (for example, when used in combination with "either" or "one of the two").

Claims

1. The substrate, and a set of layers disposed on the substrate; An optical interference filter comprising: The set of layers comprises: a first subset of layers, and a second subset of layers, and a first subset of each of the layers includes an aluminum nitride (AlN) material; the stress of the first subset of each of said layers is between −1000 and 800 megapascals; a first subset of the layers has a first refractive index having a first value; a second subset of each of said layers includes at least one other material; a second subset of the layers has a second refractive index having a second value different from the first value; The optical interference filter has an effective refractive index that is 95% or more of the highest value of the first value and the second value.

2. 10. The optical interference filter of claim 1, wherein the angular shift at the center wavelength of the optical interference filter is less than 1.0% of the center wavelength for angles of incidence between 0 and 30 degrees.

3. 10. The optical interference filter of claim 1, wherein the set of layers has a net stress of about 0 megapascals.

4. 10. The optical interference filter of claim 1, wherein the first subset of layers and the second subset of layers are disposed on the substrate in an alternating layer order.

5. 10. The optical interference filter of claim 1, wherein the at least one other material is: Silicon (Si) materials, Silicon hydrogenated (Si:H) materials, Silicon-Helium Hydrogenated (Si:H—He) materials; Silicon and hydrogen (SiH) materials, amorphous silicon (a-Si) material, Silicon nitride (SiN) material, Germanium (Ge) materials, germanium hydride (Ge:H) materials; Silicon germanium (SiGe) material, hydrogenated silicon germanium (SiGe:H) materials; Silicon carbide (SiC) material, hydrogenated silicon carbide (SiC:H) material, Silicon dioxide (SiO2) material, Tantalum pentoxide (Ta2O5) material, Niobium pentoxide (Nb2O5) material, Niobium titanium oxide (NbTiOx) materials, Niobium tantalum pentoxide (Nb2-xTaxO5) material, Titanium dioxide (TiO2) materials, Aluminum oxide (Al2O3) material, Zirconium oxide (ZrO2) material, yttrium oxide (Y2O3) material, or Hafnium oxide (HfO2) material, An optical interference filter comprising at least one of:

6. 10. The optical interference filter of claim 1, wherein an additional layer is disposed above the set of layers, the additional layer comprising a silicon dioxide (SiO2) material.

7. 10. The optical interference filter of claim 1, wherein the optical interference filter is configured to pass light associated with the 800 to 1600 nanometer spectral range.

8. a first subset of layers, and a second subset of layers, 1. An optical interference filter comprising a set of layers having: a first subset of each of the layers includes an aluminum nitride (AlN) material; a first subset of the layers has a first refractive index having a first value; a second subset of each of said layers includes a silicon hydride-helium (Si:H—He) material; a second subset of the layers has a second refractive index having a second value greater than the first value; The optical interference filter has an effective refractive index that is 95% or greater than the second value.

9. 9. The optical interference filter of claim 8, wherein one of the first subset of layers and the second subset of layers comprises a tension material; and the other of the first subset of layers and the second subset of layers comprises a compression member; Optical interference filters.

10. 9. The optical interference filter of claim 8, wherein the set of layers has a net stress of about 0 megapascals.

11. 9. The optical interference filter of claim 8, wherein the net stress of the set of layers is approximately equal to a specified amount of stress.

12. 9. An optical interference filter according to claim 8, the first value is between 1.9 and 2.2 for light having a wavelength between 500 and 5500 nanometers; An optical interference filter, wherein the second value is 3.5 to 3.9 for light having a wavelength of 500 to 5500 nanometers.

13. 9. The optical interference filter of claim 8, wherein an additional layer is disposed above the set of layers; 9. The optical interference filter of claim 8, wherein the additional layer comprises a silicon dioxide (SiO2) material.

14. 9. The optical interference filter of claim 8, wherein the optical interference filter has an angular shift of less than 7.0 nanometers (nm) at a wavelength of 940 nm for angles of incidence between 0 and 30 degrees, and the effective refractive index is 3.7 or greater.

15. 9. The optical interference filter of claim 8, wherein the angular shift at the center wavelength of the optical interference filter is less than 1.0% of the center wavelength for angles of incidence between 0 and 30 degrees.

16. 16. The optical interference filter of claim 15, wherein the center wavelength is 940 nanometers.

17. 9. The optical interference filter of claim 8, wherein the optical interference filter is associated with a transmission of 90% to 100% of a peak transmission of the optical interference filter and an angle of incidence of 0 degrees to 30 degrees.

18. A substrate, an arrangement of layers on the substrate; An optical interference filter comprising: the arrangement of layers includes a first set of layers alternating with a second set of layers; the first set of layers comprises aluminum nitride (AlN); the second set of layers comprises silicon hydride-helium (Si:H—He); An optical interference filter, wherein the arrangement of layers has an effective refractive index of 3.7 or greater.

19. 19. The optical interference filter of claim 18, wherein the stress of the first set of layers is between -1000 and 150 megapascals.

20. 19. The optical interference filter of claim 18, wherein the refractive index of the first set of layers is between 1.9 and 2.2 for light having a wavelength between 500 and 5500 nanometers.

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