Planar cell nanoh heater design and cell architecture for programmable phase change filter

Abstract

Embodiments of the present disclosure relate to planar cell nanoh heater designs and cell architectures for programmable phase change filters. A phase change filter is formed from an arrangement of dots, where each dot is made from a phase change material. A heating layer of electrically conductive material extends under the arrangement of dots. Current through the heating layer changes the dots between two states to change the attenuation of light through the filter.

Description

[0001] Priority requirements

[0002] This application claims priority to French patent application No. 2110500, filed on October 5, 2021; Greek patent application No. 20210100676, filed on October 5, 2021; and French patent application No. 2200431, filed on January 19, 2022, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0003] This invention generally relates to programmable phase-change filters, and more particularly to the design and cell architecture of planar unit nanoheaters for programmable phase-change filters. Background Technology

[0004] Refractive index changes achieved by phase change materials have been used to switch in integrated optical devices, modulate electromagnetic modes in periodic structures, and manipulate local optical contrast. Summary of the Invention

[0005] One embodiment provides a nanopore-shaped heater for optimal control of the heating front, which is adapted to a filter-specific geometry and allows optimal attainment of the critical phase transition temperature in a phase change filter.

[0006] One embodiment provides a specific geometry and current level adjustment to minimize temperature field variability within the filter region.

[0007] One embodiment provides decoupling between high-temperature and low-temperature regions, thereby allowing organic optical lenses using transparent materials to coexist near the phase change material unit region in order to: protect the optical stack from thermal degradation; minimize heating-cooling cycles; and allow high light transmittance.

[0008] One embodiment provides a phase change filter, including: a plurality of points, each point being formed of a phase change material; and a heating layer of conductive material, the heating layer including a plurality of heating regions, each heating region including one or more conductive fingers, wherein corresponding points of the points are located on each heating region of the heating layer.

[0009] One embodiment also provides a phase change filter comprising: a plurality of points, each point being formed of a phase change material, wherein the points are formed in regularly spaced columns and rows, the pitch of the points in the columns and rows being in the range of 500 nm to 1000 nm.

[0010] According to one embodiment, the number of conductive fingers in each heating region of the heating layer is equal to 2.

[0011] According to an embodiment, dots are formed in regularly spaced columns and rows.

[0012] According to one embodiment, the pitch of points in columns and / or rows is in the range of 500 nm to 1000 nm.

[0013] According to one embodiment, the pitch of the points in the columns and / or rows is such that when the points are in the first state, the optical wavelengths in the filtering range are attenuated by at least 40%, preferably at least 50% or at least 60%, wherein the filtering range includes a wavelength range of 900 nm to 1000 nm.

[0014] According to an embodiment, the filtering range includes a wavelength range of 920nm to 960nm.

[0015] According to one embodiment, the phase-change filter is a notch filter, the notch of which is centered at a center frequency in the range of 900 nm to 1000 nm, and preferably in the range of 920 nm to 960 nm, the center frequency being, for example, equal to 940 nm, or approximately 940 nm.

[0016] According to one embodiment, when the point is in the second state, the light wavelength within the filtering range is attenuated by less than 20%.

[0017] According to one embodiment, the first state is amorphous and the second state is crystalline.

[0018] According to one embodiment, the pitch of the points in the columns and rows is such that when the point is in the second state, the optical wavelength in the offset filter range is attenuated by at least 40%, preferably at least 50% or at least 60%, wherein the offset filter range does not overlap with the filter range, for example.

[0019] According to an embodiment, the conductive material of the heating layer includes indium tin oxide (ITO).

[0020] According to one embodiment, the material and thickness of the heating layer are selected to be transparent to light within the filtering range, where transparency means 20% or less attenuation.

[0021] According to one embodiment, the thickness of the heating layer is between 10 nm and 40 nm, preferably about 20 nm.

[0022] According to one embodiment, each conductive finger has a minimum width in the plane of the heating layer ranging from 50 nm to 150 nm, and preferably in the range of 75 nm to 125 nm, for example in the range of 85 nm to 115 nm, and for example equal to about 100 nm.

[0023] According to one embodiment, the maximum width of the gap between the fingers in the plane of the heating layer is in the range of 50 nm to 150 nm, and preferably in the range of 75 nm to 125 nm, for example in the range of 85 nm to 115 nm, and for example equal to about 100 nm.

[0024] According to one embodiment, each finger has a length of at least 250 nm in the plane of the heating layer, preferably at least 300 nm, for example, between 400 nm and 500 nm.

[0025] One embodiment also provides an image sensor including: a photosensitive element layer, such as a photodiode; a color and / or infrared filter layer, such as an RGBZ filter layer including R, G, B, and Z filters; and a phase-change filter stacked with each color / infrared filter as previously defined.

[0026] One embodiment also provides a method for manufacturing a phase change filter, the method comprising: forming a heating layer of conductive material, the heating layer including a plurality of heating regions, each heating region including one or more conductive fingers; and forming a plurality of points, each point being formed of the phase change material, the corresponding point being located on each heating region of the heating layer.

[0027] One embodiment also provides a method for manufacturing a phase change filter, the method comprising: forming a plurality of points, each point being formed of a phase change material, wherein the points are formed in regularly spaced columns and rows, the pitch of the points in the columns and rows being in the range of 500 nm to 1000 nm. Attached Figure Description

[0028] The foregoing features and advantages, as well as other features and advantages, will be described in detail below with reference to the accompanying drawings, which are given by way of illustration rather than limitation:

[0029] Figure 1 This is a partially simplified cross-sectional view of an embodiment of a programmable phase-change filter;

[0030] Figure 2 It shows Figure 1 The arrangement of phase transition points in the photonic crystal layer of the programmable phase transition filter;

[0031] Figure 3 It shows the effect of wavelength as a function of incident radiation. Figure 1 The curve showing the evolution of the transmittance of the photonic crystal in a programmable phase-change filter;

[0032] Figure 4 yes Figure 1 A simplified perspective view of an embodiment of a phase change filter with a heating layer and a phase change point;

[0033] Figure 5 yes Figure 4 Bottom view of the heating layer of the phase change filter;

[0034] Figure 6 yes Figure 4 A detailed bottom view of the heating layer and a portion of the associated phase transition point of the phase change filter;

[0035] Figure 7 yes Figure 1 A detailed bottom view of a portion of another embodiment of the heating layer and associated phase transition point of the phase change filter;

[0036] Figure 8 It shows the composition of having Figure 7 The temperature provided by the heating layer of the structure shown changes with respect to the current flowing through the heating layer and the thickness of the heating layer over time.

[0037] Figure 9 Similar to Figure 8 This shows the temperature change of another thickness of the heating layer;

[0038] Figure 10 The curves showing the evolution of the ratio relative to the current flowing through the heating layer for several thicknesses of the heating layer are presented.

[0039] Figure 11 The curves showing the evolution of the minimum temperature with respect to time for several thicknesses of the heating layer are presented;

[0040] Figure 12 The highest ratio is shown to vary with the current intensity flowing through the heating layer and the thickness of the heating layer;

[0041] Figure 13 The curves showing the evolution of the average temperature relative to the gap between the fingers of the heating layer for several widths of the fingers are presented.

[0042] Figure 14 The curves show the evolution of the ratio of the finger width to the gap between the fingers of the heating layer;

[0043] Figure 15 The curves showing the variation of average temperature with respect to the finger width of the heating layer for multiple finger lengths are shown.

[0044] Figure 16 The curves showing the variation of the ratio of the finger length to the finger width of the heating layer are presented.

[0045] Figure 17 The curves showing the evolution of the average temperature relative to the gap between the fingers of the heating layer for several widths of the fingers are presented.

[0046] Figure 18The curves showing the evolution of the ratio of the fingers to the gap between the fingers of the heating layer for a certain width are illustrated.

[0047] Figure 19 The curves showing the evolution of the average temperature relative to the gap between the fingers of the heating layer for multiple lengths of the fingers are presented.

[0048] Figure 20 The curves showing the evolution of the ratio of the fingers to the gap between the fingers of the heating layer for several lengths are illustrated.

[0049] Figure 21 This is a simplified cross-sectional view of an embodiment of the image sensor;

[0050] Figure 22 The evolution of the maximum temperature in a layer made of an organic coating covering the shielding layer of a phase change filter is shown as a function of the thickness of the shielding layer.

[0051] Figure 23 The evolution of the average temperature at the phase transition point relative to the thickness of the shielding layer is shown;

[0052] Figure 24 The curves showing the evolution of the average temperature over time for two thicknesses of the shielding layer are presented.

[0053] Figure 25 The evolution of this ratio relative to the thickness of the shielding layer is shown;

[0054] Figure 26 The curve showing the evolution of operating frequency relative to battery current intensity is presented;

[0055] Figure 27 -30 shows the process used in manufacturing Figure 1 The structure obtained at each step of an embodiment of the phase-change filter method. Detailed Implementation

[0056] In the various figures, the same features are indicated by the same reference numerals. In particular, common structural and / or functional features in the various embodiments may have the same reference numerals and may have the same structure, dimensions, and material properties.

[0057] For clarity, only the operations and elements that can be used to understand the embodiments described herein are described in detail.

[0058] Unless otherwise stated, when referring to two elements connected together, it means that there is no direct connection between them except for the conductor, and when referring to two elements connected together, it means that the two elements can be connected or they can be coupled through one or more other elements.

[0059] In the following disclosure, unless otherwise stated, when referring to absolute position qualifiers, such as the terms “front,” “back,” “top,” “bottom,” “left,” “right,” etc., or when referring to relative position qualifiers, such as the terms “up,” “down,” “higher,” “lower,” etc., or when referring to orientation qualifiers, such as “horizontal,” “vertical,” etc., the orientation shown in the figure is used.

[0060] Unless otherwise stated, the expressions “about,” “approximately,” “basically,” and “in the order of” indicate within 10%, preferably within 5%.

[0061] In the following description, "visible light" refers to electromagnetic radiation with wavelengths in the range of 400 nm to 700 nm, while "infrared radiation" (IR) refers to electromagnetic radiation with wavelengths in the range of 700 nm to 1 mm. Within infrared radiation, near-infrared radiation (NIR) with wavelengths in the range of 700 nm to 1.4 μm can be specifically distinguished. Furthermore, in the following description, "useful radiation" refers to electromagnetic radiation that passes through the optical system during operation and is captured by detectors associated with the optical system.

[0062] In the remainder of the specification, the internal transmittance of a layer corresponds to the ratio between the intensity of radiation leaving the layer and the intensity of radiation entering the layer, with the incident radiation rays perpendicular to the layer. The absorptivity of the layer is equal to the difference between 1 and the internal transmittance. In the remainder of the specification, a layer or film is said to be transparent to radiation when the absorption of radiation passing through it is less than 20%. In the remainder of the specification, the refractive index of a material corresponds to the refractive index of the material at the wavelength of the useful radiation.

[0063] Figure 1 This is a partially simplified cross-sectional view of an embodiment of the programmable phase-change filter 10. In one embodiment, the programmable phase-change filter 10 acts as an optical notch filter. The programmable phase-change filter 10 includes an upper surface 12 that receives incident electromagnetic radiation IL and a lower surface 14 opposite to the upper surface 12 that provides transmitted electromagnetic radiation TL. Preferably, the upper surface 12 and the lower surface 14 are parallel. Preferably, the upper surface 12 and the lower surface 14 are planar.

[0064] The programmable phase-change filter 10 includes stacking, in Figure 1 The middle layer, from bottom to top, includes: a base layer 20 defining a lower surface 14; a heating layer 22 placed on the base layer 20, preferably in physical contact with the base layer 20; a phase change point 24 located on the heating layer 22, preferably in physical contact with the heating layer 22; an intermediate layer 26 covering the heating layer 22 between the phase change point 24, preferably in physical contact with the heating layer 22 between the phase change point 24; and a shielding layer 28 defining an upper surface 12 resting on the intermediate layer 26, preferably in physical contact with the intermediate layer 26.

[0065] The layer containing phase transition point 24 and a portion of the intermediate layer 26 between phase transition point 24 form a photonic crystal PC.

[0066] Figure 2 This is a partial and schematic enlarged top view of an embodiment of a photonic crystal PC.

[0067] According to one embodiment, each phase transition point 24 is substantially cylindrical or frusto-conical in shape, having a central axis perpendicular to the upper surface 12 at a height H measured perpendicular to the upper surface 12, and having a base of an elliptical, circular, or polygonal shape, particularly triangular, rectangular, square, or hexagonal, preferably circular. The term "average diameter" used in relation to the bottom of the phase transition point 24 refers to a quantity related to the surface area of ​​the bottom, for example, corresponding to the diameter of a disk having the same surface area as the bottom. The average diameter D of each phase transition point 24 is in the range of 50 nm to 1500 nm, preferably in the range of 100 nm to 300 nm. The height H of each phase transition point 24 is in the range of 20 nm to 300 nm, preferably in the range of 60 nm to 150 nm.

[0068] Phase transition points 24 are located on the heating layer 22 and are spaced a certain distance from each other. According to an embodiment, the phase transition points 24 are arranged, for example, in a regular array on the heating layer 22. Figure 2 In one embodiment, phase transition points 24 are arranged in a rectangular grid. This means that the phase transition points 24 are arranged in rows and columns, with the center of each phase transition point 24 located at a vertex of the rectangle. Two adjacent phase transition points 24 in the same row are separated by a row pitch Pr, and two adjacent phase transition points 24 in the same column are separated by a column pitch Pc. According to another embodiment, the phase transition points 24 are arranged in a hexagonal grid. This means that in a top view, the phase transition points 24 are arranged in rows, with the center of each phase transition point 24 located at a vertex of an equilateral triangle. The centers of two adjacent phase transition points 24 in the same row are separated by a row pitch Pr, and the centers of two adjacent rows are offset by a distance Pr / 2 in the direction of the row. The pitch Pr between two adjacent phase transition points 24 in a row is in the range of 500 nm to 1000 nm. According to one embodiment, the pitch Pr between each phase transition point 24 and the nearest phase transition point 24 in a row is substantially constant. The pitch Pc between two adjacent phase transition points 24 in a column is in the range of 200 nm to 1000 nm. According to one embodiment, the pitch Pc between each phase transition point 24 in a column and the nearest phase transition point 24 is substantially constant. Pitches Pr and Pc can be equal.

[0069] Each phase transition point 24 is made of a phase transition material that undergoes a solid / solid phase transition between the first and second states by absorbing or releasing heat, and has different refractive indices in the first and second states. According to one embodiment, the first state is amorphous and the second state is crystalline.

[0070] According to an embodiment, each phase transition point 24 is made of a phase transition chalcogenide material, such as Sb₂S₃, Sb₃Se₃, GeTe, GeTeN, germanium-antimony-tellurium alloy (GeSbTe or GST), particularly Ge₂Sb₂Te₅, or phase transition vanadium oxide, particularly VO₂. According to one embodiment, the phase transition temperature of each phase transition point 24 is in the range of 500K to 1100K for phase transition chalcogenide materials and in the range of 350K to 450K for VO₂ type materials.

[0071] According to one embodiment, the intermediate layer 26 is made of an electrically insulating material. The intermediate layer 26 may have a single-layer or multi-layer structure. According to one embodiment, the intermediate layer 26 is made of a dielectric material, such as silicon oxide (SiO2), silicon nitride (SiN, or SiO2). x N y Where x is approximately equal to 3 and y is approximately equal to 4, for example, Si3N4), silicon oxynitride (especially the general formula SiO2). x N y It is made of materials such as Si2ON2, hafnium oxide (HfO2), aluminum oxide (Al2O3), or amorphous silicon carbide (a-SiC). According to one embodiment, the thickness of the intermediate layer 26 includes between 0.1 μm and 10 μm, preferably between 0.2 μm and 0.6 μm.

[0072] According to one embodiment, when the phase transition point 24 is in a first state, the optical wavelength within the filtering range is attenuated by the phase transition filter 10 by at least 40%, preferably at least 50% or at least 60%, and when the phase transition point 24 is in a second state, the optical wavelength within the filtering range is attenuated by less than 20%. The filtering range includes a wavelength range of 900 nm to 1000 nm, preferably in the wavelength range of 920 nm to 960 nm. The phase transition filter 10 is a notch filter, the notch of which is centered, for example, at a center frequency in the range of 900 nm to 1000 nm, and preferably in the range of 920 nm to 960 nm, the center frequency being, for example, equal to or approximately 940 nm.

[0073] When the point is in the second state, the light wavelength within the offset filtering range is attenuated by at least 40%, preferably at least 50% or at least 60%, wherein the offset filtering range does not overlap with the filtering range, for example.

[0074] Each of the base layer 20, heating layer 22, phase transition point 24, intermediate layer 26, and shielding layer 28 is transparent to incident radiation IL within the filtering range.

[0075] Figure 3 Curves A1 and A2 represent the evolution of the transmittance TR of the photonic crystal PC of the programmable phase-change filter 10 as a function of the wavelength WL of the incident radiation for two temperatures. Figure 2 The curves shown indicate that phase transition point 24 is made of Sb₂S₃ and separated by SiO₂. Each phase transition point 24 is a cylinder with a height H of 50 nm and a circular substrate with a diameter of 200 nm. The pitches Pr and Pc are 600 nm. The resulting photonic crystal PC is used as a notch filter. When the phase transition material (here, Sb₂S₃) is in the amorphous state, the notch filter cuts out radiation with a wavelength less than 900 nm (curve A1), while when the phase transition material (here, Sb₂S₃) is in the crystalline state, the notch filter cuts out radiation with a wavelength equal to 940 nm (curve A2).

[0076] Figure 4 This is a simplified perspective view of the heating layer 22 shown in solid lines and the phase transition point 24 shown in dashed lines. Figure 5 This is a bottom view of the heating layer 22. Figure 6 yes Figure 5 A detailed bottom view of a portion of the heating layer 22 and the associated phase transition point 24. (Compared to...) Figure 6 similar, Figure 7 Another embodiment of the heating layer 22 is shown.

[0077] The heating layer 22 includes strips 30, adjacent strips are connected by fingers 32, and four strips 30 are in Figure 4 and 5 The middle portion is shown. According to an embodiment, when the phase transition points 24 are arranged in rows and columns, the strips 30 can extend substantially parallel. Figure 4 The direction of the current I passing through the heating layer 22 is shown.

[0078] Two adjacent strips 30 are connected by a plurality of fingers 32. Each phase transition point 24 is located on at least one finger 32 and may be partially located on the strip 30 connected by that finger 32. Figure 4 In the embodiments shown in 5 and 6, each phase transition point 24 is located on two fingers 32 and is in physical contact with the upper surface of each of the two fingers 32. In this embodiment, each pair of adjacent fingers 32 forms a heating region 33. Figure 6 In this configuration, each phase transition point 24 is also partially located on the strip 30 connected by the two fingers 32. As a variation, each phase transition point 24 may be located only on the two fingers, and not on the strip connected by the two fingers 32. Figure 7In the illustrated embodiment, each phase transition point 24 is placed on a finger 32 that is in physical contact with the upper surface of the finger 32. In this embodiment, each finger 32 forms a heating region 33. Figure 7 In this configuration, each phase transition point 24 is not partially located on the strip 30 connected by the fingers 32. As a variation, each phase transition point 24 may also be partially located on the strip connected by the fingers 32.

[0079] According to one embodiment, each finger 32 connected to two adjacent strips 30 includes two flared portions 34, 36, which are connected to each other at their narrowest ends, and each flared portion 34, 36 is connected to one of the strips 30 at its widest end. According to one embodiment, in the plane of the heating layer 22, the length L of each finger 32, i.e., the distance between two adjacent strips 30 at the horizontal level of the finger 32, is at least 250 nm, and preferably at least 300 nm, for example, between 400 nm and 500 nm. According to one embodiment, the width of each strip 30, except for two strips 30 that may originate from two opposite sides forming the heating layer 22, is in the range of 50 nm to 200 nm. The gap G between the fingers 32 and the space between the strips 30 can be filled with an intermediate layer 26. The maximum width of the gap G between the fingers 32 in the plane of the heating layer 22 is in the range of 50 nm to 150 nm, and preferably in the range of 75 nm to 125 nm, for example in the range of 85 nm to 115 nm, and for example equal to about 100 nm. At the junction of the fingers 32 and the strip 30, the width Wj of the fingers 32 is in the range of 50 nm to 200 nm. The minimum width W of the fingers 32 is in the range of 50 nm to 150 nm, and preferably in the range of 75 nm to 125 nm, for example in the range of 85 nm to 115 nm, and for example equal to about 100 nm. The minimum width W of the fingers 32 is referred to as the width W of the fingers 32 in the remainder of the specification.

[0080] In embodiments where each phase transition point 24 is located on a pair of adjacent fingers 32, the minimum distance between the fingers of a pair of adjacent fingers 32 is in the range of 20 nm to 200 nm. In embodiments where each phase transition point 24 is located on a pair of adjacent fingers 32, the minimum distance between the fingers 32 of two pairs of adjacent fingers 32 is in the range of 200 nm to 600 nm. It should be noted that the dimensions of a notch filter for cutting radiation at approximately 940 nm are given, but if a notch filter for cutting radiation in visible light or short-wave infrared is to be obtained, the structure can have different dimensions (from 100 nm to 1 μm).

[0081] The heating layer 22 is made of a material with good thermal conductivity. According to one embodiment, the heating layer 22 is made of a conductive material. According to another embodiment, the heating layer 22 is made of a transparent and conductive material, such as indium tin oxide (ITO) doped or undoped with aluminum or gallium, zinc oxide, or graphene. According to one embodiment, the thickness Th of the heating layer 22 includes between 10 nm and 40 nm, and is preferably about 20 nm.

[0082] According to an embodiment, the base layer 20 is made of an electrically insulating material or a semiconductor material. The base layer 20 may have a single-layer structure or a multi-layer structure. According to an embodiment, the base layer 20 is made of silicon oxide (SiO2). According to an embodiment, the thickness of the base layer 20 includes between 100 nm and 1 μm.

[0083] The shielding layer 28 is made of a material with good thermal conductivity. According to one embodiment, the shielding layer 28 is made of a conductive material. According to an embodiment, the shielding layer 28 is made of a transparent and conductive material, such as indium tin oxide (ITO) doped or undoped with aluminum or gallium, zinc oxide, or graphene. According to an embodiment, the thickness Th_S of the shielding layer 28 is in the range of 30 nm to 200 nm, preferably in the range of 50 nm to 80 nm. The shielding layer 28 and the heating layer 22 can be made of the same material.

[0084] Heating layer 22 is used according to Figure 4 The direction indicated by the middle arrow I provides heat through the Joule effect by allowing current to flow through the fingers 32, so that the same intensity of current flows through each finger 32.

[0085] Figure 8 and 9 The evolution of the volume average temperature T on the surface of the finger 32 in contact with the phase transition point 24 relative to the current intensity I flowing through each finger 32 and time t, obtained by simulation, is shown for two-thickness heating layers 22. For these simulations, the heating layer 22 has… Figure 7 The structure shown. The length L of each finger 32 is equal to 500 nm. The maximum width Wj of each finger 32 is equal to 400 nm. The width W of each finger 32 is equal to 100 nm. For Figure 8 The thickness Th of the heating layer 22 is 10 nm. Figure 9 The thickness of the heating layer 22 is 15nm. Figure 8 and 9 The temperature at which the phase transition triggers the phase transition point 24 can be provided by the heating layer 22.

[0086] Figure 10Curves C1_10, C1_15, C1_20, C1_25, C1_30, C2_10, C2_15, C2_20, C2_25 and C2_30 are shown for several thicknesses of the heating layer 22, showing the evolution of the highest ratio Tndiff obtained with respect to the current I flowing through each finger 32 of the heating layer 22 over time. The ratio Tndiff is given by the following relationship (1):

[0087] Tndiff = (Tavg - Tmin) / Tmin

[0088] Where Tavg is the average temperature at phase transition point 24, and Tmin is the lowest temperature at phase transition point 24. For curves C1_10, C1_15, C1_20, C1_25, and C1_30, the heating layer 22 has Figure 7 The structure shown, namely having a finger 32 at phase transition point 24, and having the same characteristics as previously described, except that the thicknesses Th are 10 nm, 15 nm, 20 nm, 25 nm and 30 nm respectively. Figure 8 The dimensions disclosed are the same. For curves C2_10, C2_15, C2_20, C2_25, and C2_30, the heating layer 22 has... Figure 6 The structure shown, namely having two fingers 32 passing through the phase transition point 24, and having thicknesses Th equal to 10 nm, 15 nm, 20 nm, 25 nm, and 30 nm respectively, has the same characteristics as previously discussed. Figure 8 The publicly disclosed dimensions are the same as the dimensions. Figure 10 Showing for Figure 6 The structure shown has a reduced temperature change at phase transition point 24, meaning that there are two fingers 32 at phase transition point 24.

[0089] for Figures 11 to 20 The heating layer 22 has Figure 6 The structure shown has two fingers 32, represented by the phase transition point 24, and unless otherwise indicated, has the previously mentioned... Figure 10 Publicly available dimensions.

[0090] Figure 11The graphs D10, D15, D20, D25, and D30 show the evolution of the lowest temperature Tmin at the phase transition point 24 with respect to time t for heating layers 22 of various thicknesses. Current is supplied at t = 0 ns and stopped at t = 380 ns. Curve D10 is obtained for a thickness Th of 10 nm and a current intensity of 1000 μA; curve D15 is obtained for a thickness Th of 15 nm and a current intensity of 1300 μA; curve D20 is obtained for a thickness Th of 20 nm and a current intensity of 1600 μA; curve D25 is obtained for a thickness Th of 25 nm and a current intensity of 2000 μA; and curve D30 is obtained for a thickness Th of 30 nm and a current intensity of 2300 μA. This figure shows the temperature suitable for triggering the phase transition at 350 ns.

[0091] Figure 12 The variation of the highest ratio Tndiff, obtained by simulation, is shown as a function of time relative to the current intensity I flowing through each finger 32 of the heating layer 22 and the thickness Th of the heating layer 22.

[0092] for Figure 13 and 14 The current intensity flowing through each finger 32 of the heating layer 22 is equal to 1700 μA. These figures were obtained at a time of 350 ns.

[0093] Figure 13 Curves E100, E150, and E200 are shown illustrating the evolution of the average temperature Tavg at the phase transition point 24 relative to the gap G for several widths W of the fingers 32 of the heating layer 22. Curve E100 is obtained for a width W of 100 nm, curve E150 for a width W of 150 nm, and curve E200 for a width W of 150 nm. Advantageously, the average temperature Tavg is the highest.

[0094] Figure 14 Curves F100, F150, and F200 show the evolution of the ratio Tmax_min relative to the gap G for several widths of the fingers 32 of the heating layer 22. The ratio Tmax_min is given by the following relationship (2):

[0095] Tmax_Min=(Tmax-Tmin) / Tavg

[0096] Where Tmax is the highest temperature at phase transition point 24. Curve F100 is obtained for a width W of 100 nm, curve F150 for a width W of 150 nm, and curve F200 for a width W of 150 nm. Advantageously, the ratio Tmax_min is the lowest.

[0097] for Figure 15and 16 The simulation was performed at a time of 350 ns, with a gap G of 100 nm.

[0098] Figure 15 Curves G100, G200, G300, G400, and G500 are shown for several lengths L of the finger 32 of the heating layer 22, depicting the evolution of the average temperature Tavg at the phase transition point 24 relative to the width W. Curves G100, G200, G300, G400, and G500 were obtained for lengths L of 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, respectively.

[0099] Figure 16 Curves H100, H200, H300, H400, and H500 are shown for the evolution of the ratio Tmax_min at the phase transition point 24 relative to the width W for several lengths L of the fingers 32 of the heating layer 22. Curves H100, H200, H300, H400, and H500 were obtained for lengths L of 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, respectively.

[0100] for Figure 17 and 18 The simulation is performed in a time of 350 ns and the length L is 200 nm.

[0101] Figure 17 Curves I100, I150, and I200 are shown for several widths W of the finger 32 of the heating layer 22, showing the variation of the average temperature Tavg at the phase transition point 24 with respect to the gap G. Curve I100 is obtained for a width W of 100 nm, curve I150 is obtained for a width W of 150 nm, and curve I200 is obtained for a width W of 150 nm.

[0102] Figure 18 Curves J100, J150, and J200 are shown for the evolution of the average ratio Tmax_min at the phase transition point 24 relative to the gap G for several widths of the fingers 32 of the heating layer 22. Curve J100 is obtained for a width W of 100 nm, curve J150 is obtained for a width W of 150 nm, and curve J200 is obtained for a width W of 150 nm.

[0103] for Figure 19 and 20 The simulation was performed in a time of 350 ns, and the width W was 150 nm.

[0104] Figure 19Curves K100, K200, K300, K400, and K500 are shown for several lengths L of the fingers 32 of the heating layer 22, depicting the evolution of the average temperature Tavg at the phase transition point 24 relative to the gap G. Curves K100, K200, K300, K400, and K500 were obtained for lengths L of 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, respectively.

[0105] Figure 20 Curves L100, L200, L300, L400, and L500 are shown for the evolution of the ratio Tmax_min at the phase transition point 24 relative to the gap G for several lengths L of the fingers 32 of the heating layer 22. Curves L100, L200, L300, L400, and L500 were obtained for lengths L of 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, respectively.

[0106] Figure 21 This is a partially simplified cross-sectional view of an embodiment of image sensor 40. Image sensor 40 includes RGBZ pixels.

[0107] Image sensor 40 includes a stack, which is stacked in Figure 21 From bottom to top, it includes: a bracket 42; an image sensor circuit 44; a programmable phase-change filter 10; a color / infrared filter 46 for each pixel; and a lens 48 for each pixel.

[0108] The image sensor circuit 44 includes a semiconductor substrate 50 and a stack of interconnect layers 52 located on the side of a support 42. The semiconductor substrate 50 is separated into semiconductor portions 54 by insulating walls 56, each semiconductor portion 54 being covered by a color / infrared filter 46 and a lens 48. Each semiconductor portion 54 may include a photosensitive element, such as a photodiode PH. Transistors (TMOS) may be formed in and on the substrate 50. The image sensor 40 may also include an interferometric filter (not shown). Each color filter 46 selectively allows a single color to pass through and is transparent to IR. The color filters 46 and the lens 48 may be made of organic materials, such as polymers.

[0109] The programmable phase-change filter 10 covers all of the semiconductor portion 54 and acts as an all-pass filter that filters only a given wavelength (preferably IR or NIR). By applying a voltage / current in the heater layer 22 of the programmable phase-change filter 10 to allow filtering or to allow the target wavelength window to pass through, a shift in the wavelength of the target filtering window can be caused.

[0110] Image sensor 40 can be an RGBZ sensor, particularly one using Time-of-Flight (ToF) technology. Known RGBZ technologies are limited by the inability to filter light and stack pixels. In practice, it is impossible to perform voluntary IR sensing or visible light sensing at the same x, y array locations, i.e., on the same pixels, because visible pixels are contaminated by IR radiation. Furthermore, in known RGBZ image sensors, stacking only IR-sensitive pixels onto only visible-sensitive pixels requires extremely complex integration, with the most promising on-paper solutions requiring 3D heterogeneous integration of III-VIR pixels stacked on top of Si visible-sensitive pixels.

[0111] The phase-change filter 10 of the image sensor 40 allows for IR sensing or visible light sensing at the same x, y array locations (i.e., the same pixels) because the phase-change filter 10 can be controlled to filter IR radiation, preventing visible pixels from being contaminated by IR radiation. The phase-change filter 10 is formed on all pixels of the image sensor 40, thus eliminating the need for complex integration. The image sensor 40 can use a single standard Si pixel for both visible light and IR sensing.

[0112] The heating layer 22 allows for phase transition induction while maintaining low current consumption and a high package factor. The heating layer 22 of the phase change filter 10 is optimized to achieve the target temperature while minimizing temperature non-uniformity at the phase transition point 24. The shielding layer 28 of the phase change filter 10 also allows for thermal management of the environment of the phase change filter 10 to separate the beneficial high local temperature from harmful overheating of the entire pixel array, particularly achieving thermal localization and thermal leading edge control to protect the organic optics.

[0113] for Figures 22 to 25 The heating layer 22 has Figure 6 The structure shown has two fingers 32 at the phase transition point 24, with a gap G and width W both equal to 100 nm and a length equal to 200 nm. The external temperature of the image sensor 40 is 300 K.

[0114] Figure 22 The evolution of the maximum temperature Tmasp in a color filter 46 corresponding to the layer made of poly(methylmethacrylate) (PMMA) covering the shielding layer 28 with respect to the thickness Th_S of the shielding layer 28 is shown. Figure 22 The shielding layer 28 is shown to prevent temperature rise in the color filter 46.

[0115] Figure 23 The evolution of the average temperature Tavg at phase transition point 24 relative to the thickness Th_S of shielding layer 28 is shown. Figure 23 The shielding layer 28 is shown to allow thermal front localization at the phase transition point 24.

[0116] Figure 24 Curves M20 and M200 are shown for the evolution of the average temperature Tavg at the phase transition point 24 with respect to time t for two thicknesses of the shielding layer 28. Curve M20 is obtained for a thickness of 20 nm in the shielding layer 28, and curve M200 is obtained for a thickness of 200 nm in the shielding layer 28.

[0117] Figure 25 The evolution of the ratio Tmax_min at phase transition point 24 relative to the thickness Th_S of shielding layer 28 is shown.

[0118] Figure 26 The curves N100, N1000, and N10000 show the evolution of the operating frequency OF relative to the battery current intensity CCI (mA). For values ​​including 10... 7 Image sensor 40 of an array of units obtains Figure 26 .

[0119] Figures 27 to 30 This is a cross-section, partial view, and schematic diagram of a structure obtained in successive steps of an embodiment of a method for manufacturing a programmable phase-change filter 10. The method includes the following successive steps:

[0120] Figure 27 Etching an opening 52 in the substrate 50. The substrate 50 may correspond to the previously disclosed base layer 22 and may correspond to a semiconductor substrate 52 or an oxide layer covering the semiconductor substrate 52.

[0121] Figure 28 A thin layer 54 is deposited on the substrate 50, and a material layer 56 of the heating layer 22 is deposited to completely fill the opening 62. Layer 54 can be used as an etch stop layer.

[0122] Figure 29 Etch layer 56 down to the upper surface of substrate 50 outside opening 52. Then obtain heating layer 22.

[0123] Figure 30 The formation of phase transition point 24, intermediate layer 26, shielding layer 28 and color filter 46.

[0124] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these embodiments can be combined, and other variations will be readily apparent to them.

[0125] Finally, based on the functional descriptions provided above, the actual implementation of the embodiments and variations described herein is within the capabilities of those skilled in the art.

Claims

1. A phase-change filter, comprising: Multiple phase change material points; as well as Heating layer of conductive material; The heating layer includes multiple heating zones, each of which includes one or more conductive fingers; as well as The phase change material points are located on each heating region of the heating layer, the one or more conductive fingers are located between two adjacent strips, and each phase change material point is located on at least one conductive finger. The two adjacent strips are located on the heating layer and are connected by the one or more conductive fingers.

2. The phase change filter according to claim 1, wherein the one or more conductive fingers comprise two conductive fingers in each heating region of the heating layer.

3. The phase change filter according to claim 1, wherein the phase change material points are arranged in regularly spaced columns and rows.

4. The phase change filter of claim 3, wherein the pitch of the phase change material points in one or more of the columns and rows is in the range of 500 nm to 1000 nm.

5. The phase change filter of claim 3, wherein the pitch of the phase change material points in one or more of the columns and rows is such that when the phase change material points are in a first state, the optical wavelength in the filtering range is attenuated by 40% to 60%, wherein the filtering range includes a wavelength range of 900 nm to 1000 nm.

6. The phase change filter of claim 3, wherein the pitch of the phase change material points in one or more of the columns and rows is such that when the phase change material points are in a first state, the optical wavelength in the filtering range is attenuated by 40% to 60%, wherein the filtering range includes a wavelength range of 920 nm to 960 nm.

7. The phase change filter of claim 3, wherein the pitch of the phase change material points in one or more of the columns and rows is such that when the phase change material points are in a second state, the optical wavelength in the offset filtering range is attenuated by 40% to 60%, wherein the offset filtering range does not overlap with the filtering range.

8. The phase change filter according to claim 1, wherein when the phase change material point is in a first state, the light wavelength within the filtering range is attenuated by 40% to 60%, and wherein when the phase change material point is in a second state, the light wavelength within the filtering range is attenuated by less than 20%.

9. The phase-change filter of claim 8, wherein the first state is amorphous and the second state is crystalline.

10. The phase-change filter according to claim 1, wherein the phase-change filter is a notch filter, and the notch of the notch filter has a center frequency in the range of 900 nm to 1000 nm.

11. The phase change filter according to claim 1, wherein the conductive material of the heating layer comprises indium tin oxide.

12. The phase change filter of claim 1, wherein the material and thickness of the heating layer are transparent to light within the filtering range, wherein transparency implies 20% or less attenuation.

13. The phase change filter of claim 1, wherein the heating layer has a thickness between 10 nm and 40 nm.

14. The phase change filter of claim 1, wherein each conductive finger has a minimum width in the plane of the heating layer in the range of 50 nm to 150 nm.

15. The phase change filter of claim 1, wherein the gap between the conductive fingers has a maximum width in the plane of the heating layer in the range of 50 nm to 150 nm.

16. The phase change filter of claim 1, wherein each conductive finger has a length of at least 250 nm in the plane of the heating layer.

17. An image sensor, comprising: Photosensitive element layer; Layers for color filters and infrared filters; as well as The phase-change filter according to claim 1 is stacked with the color filter and the infrared filter.

18. A method for manufacturing a phase-change filter, comprising: A heating layer of conductive material is formed, the heating layer comprising multiple heating regions, each heating region comprising one or more conductive fingers; as well as Multiple phase change material points are formed, wherein the phase change material points are located on each heating region of the heating layer, the one or more conductive fingers are located between two adjacent strips, and each phase change material point is located on at least one conductive finger, the two adjacent strips are located on the heating layer and are connected by the one or more conductive fingers.

19. A phase-change filter according to claim 1, comprising: Multiple phase change material points, wherein the phase change material points are arranged in regularly spaced columns and rows, wherein the pitch of the phase change material points in the columns and rows is in the range of 500 nm to 1000 nm.

20. The phase change filter of claim 19, wherein the pitch of the phase change material points in one or more of the columns and rows is such that when the phase change material points are in a first state, the optical wavelength in the filtering range is attenuated by 40% to 60%, and wherein the filtering range is in the wavelength range of 900 nm to 1000 nm.

21. The phase-change filter of claim 20, wherein the filtering range is in the wavelength range of 920 nm to 960 nm.

22. The phase-change filter of claim 20, wherein the phase-change filter is a notch filter, wherein the notch of the notch filter has a center frequency in the range of 900 nm to 1000 nm.

23. The phase change filter according to claim 20, wherein when the phase change material point is in the second state, the light wavelength within the filtering range is attenuated by less than 20%.

24. The phase-change filter of claim 23, wherein the first state is amorphous and the second state is crystalline.

25. The phase change filter of claim 20, wherein the pitch of the phase change material points in one or more of the columns and rows is such that when the phase change material points are in a second state, the optical wavelength in the offset filtering range is attenuated by 40% to 60%, wherein the offset filtering range does not overlap with the filtering range.

26. A method for manufacturing the phase-change filter as claimed in claim 1, the method comprising: Multiple phase change material points are formed, each point being formed of phase change material, wherein the phase change material points are formed in regularly spaced columns and rows, wherein the pitch of the phase change material points in the columns and rows is in the range of 500 nm to 1000 nm.

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