CN111913243A

CN111913243A - Method for manufacturing one or more nanofiltered super surface elements or systems

Info

Publication number: CN111913243A
Application number: CN201910381514.9A
Authority: CN
Inventors: 高登; 姚金哈斯
Original assignee: Beiting Xingyun Technology Beijing Co ltd
Current assignee: Beiting Xingyun Technology Beijing Co ltd
Priority date: 2019-05-08
Filing date: 2019-05-08
Publication date: 2020-11-10

Abstract

A method for fabricating one or more nanofiltered supersurface elements or systems is provided. Systems and methods for integrating transmissive nanofilter materials with other semiconductor devices or additional nanofilter super surface elements are also provided, and more particularly, to integration of such nanofilter materials with substrates, illumination sources, and sensors. The provided nanofiltered super surface elements can be used to shape the output light from an illumination source or collect light reflected from a scene to form two unique patterns using polarization of light. In such embodiments, the shaped emission and collection may be combined into a single, co-designed detection and sensing optical system.

Description

Method for manufacturing one or more nanofiltered super surface elements or systems

Technical Field

The present disclosure relates to the field of optics, and in particular to methods of making one or more nanofiltered supersurface elements or systems.

Background

The nanofiltration supersurface element is a diffractive optical device, wherein the individual waveguide elements have sub-wavelength spacing and have a planar profile. Nanofiltration super surface elements have recently been developed for the ultraviolet-infrared band (300-. Compared to conventional refractive optics, the nanofiltered super-surface element introduces a sudden phase shift in the optical field. This allows the thickness of the nanofiltered super surface elements to be on the order of the wavelength of light they are designed to operate with, whereas the thickness of conventional refractive surfaces is 10-100 times (or more) greater than the wavelength of light they are designed to operate with. Furthermore, the thickness of the nano-filtered super surface elements in the constituent elements does not vary, and therefore the light can be shaped without any curvature as required by refractive optics. Compared to conventional Diffractive Optical Elements (DOEs) (e.g. binary diffractive optics), at least the nano-filtering super-surface element may have a phase shift between 0-2 pi, wherein the phase shift has at least 5 different values of the range, whereas binary DOEs can only impart two different phase shift values and is typically limited to a phase shift of 0 or 1 pi. In contrast to a multi-level DOE, the nanofiltration super surface elements do not require their constituent elements to have height variations along the optical axis, only the in-plane geometry of the nanofiltration super surface elements features variations.

Disclosure of Invention

The present application relates to methods of making one or more nanofiltering super surface elements or systems.

Many embodiments relate to a method for fabricating one or more nanofiltering super surface elements or systems, comprising:

depositing a layer of hard mask material on at least one surface of a substrate, wherein the substrate is transparent to light over a specified operating bandwidth;

depositing a pattern material layer on the hard mask material layer;

patterning the patterned material to form an array pattern on top of the layer of hard mask material, the array pattern including one of a positive reproduction (positive reproduction) or a negative reproduction (negative reproduction) of an array of nano-filtered super-surface features, the array of nano-filtered super-surface features including a plurality of nano-filtered super-surface features having a feature size smaller than a wavelength of light within a specified operating bandwidth and configured to impart a phase shift to incident light within a plane of the plurality of nano-filtered super-surface features;

etching the hard mask material layer using an anisotropic etching process to form a plurality of voids and raised features corresponding to the array pattern in the hard mask; and

any remaining pattern material is removed from the top of the hard mask material layer.

In many other embodiments, the substrate is formed from a material selected from the group consisting of fused silica, sapphire, borosilicate glass, and rare earth oxide glass.

In many other embodiments, the hard mask material layer is formed of a material selected from the group consisting of silicon, various stoichiometries of silicon nitride, silicon dioxide, titanium dioxide, aluminum oxide, and is disposed using a deposition process selected from the group consisting of sputtering, chemical vapor deposition, and atomic layer deposition.

In many other embodiments, the pattern material layer is formed from one of a photoresist patterned using a photolithographic process or a polymer patterned using a nanoimprint process.

In many other embodiments, the array pattern is etched using a reactive ion etching process selected from the group consisting of SF6, Cl2, BCl3, C4F8, or any static or multiple mixture thereof.

In many other embodiments, the residual pattern material is removed using a process selected from the group consisting of a chemical solvent, a chemical etchant, and a plasma etchant.

In many other embodiments, the patterned hard mask material is a dielectric and forms nanofilter super-surface features of the nanofilter super-surface elements.

In many other embodiments, the method further comprises:

depositing a dielectric nanofiltration meta-surface material layer on the patterned hard mask material layer such that the nanofiltration meta-surface material layer fills voids in the hard mask material layer and extends over raised features of the hard mask material layer, thereby forming a capping layer of the nanofiltration meta-surface material on top of the hard mask material layer; and

the capping layer is planarized such that the nanoliter subsurface material layer and the hard mask material layer terminate at a uniform height above the substrate.

In many other embodiments, the nanofiltration meta-surface material layer is formed of a material selected from the group consisting of silicon, various stoichiometries of silicon nitride, silicon dioxide, titanium dioxide, aluminum oxide, and deposited using a conformal process selected from the group of chemical vapor deposition and atomic layer deposition.

In many other embodiments, the planarization uses a process selected from an etch process selected from the group consisting of wet etching and plasma etching, or a chemical mechanical planarization technique.

In many other embodiments, the nanofiltered meta-surface material disposed in the voids forms nanofiltered meta-surface features of the nanofiltered meta-surface component, and wherein the hard mask material is configured as an embedding material having a lower index of refraction than the nanofiltered meta-surface material at a specified operating bandwidth.

In many other embodiments, the method further includes depositing an inlay material layer over the isolated nano-filtered meta-surface features such that air gaps between the features are filled and such that the inlay material layer extends over a surface of the nano-filtered meta-surface material layer, wherein the inlay material layer has a lower index of refraction than the nano-filtered meta-surface material at the specified bandwidth of operation.

In many other embodiments, the embedding material is a polymer selected from the group consisting of polymethylmethacrylate, SU8, and benzocyclobutene.

In many other embodiments, the embedding material is a solid film selected from the group consisting of silicon dioxide, aluminum oxide, titanium dioxide, silicon nitride, hafnium oxide, zinc oxide, and spin-on glass.

In many other embodiments, the method further includes planarizing the layer of embedding material such that the layer of nano-filtered meta-surface material and the layer of embedding material terminate at a uniform height above the substrate.

In many other embodiments, the method further comprises depositing an anti-reflective coating on top of the layer of embedding material and/or on top of a side of the substrate disposed opposite the nanofiltered super surface element.

In many other embodiments, the anti-reflective coating is comprised of alternating layers of any combination of materials selected from the group consisting of silicon dioxide, titanium dioxide, aluminum oxide, silicon nitride, aluminum nitride, and amorphous silicon, wherein the thickness of each alternating layer is less than the wavelength of light within the operating bandwidth.

In many other embodiments, the substrate is disposed on top of or is itself an illuminator or sensor.

In many other embodiments, the substrate has a substrate thickness that is not suitable for use with the target optical system, and the method further comprises at least one of:

removing at least a portion of the back side of the substrate by grinding and/or chemical etching; and is

The other substrates are aligned and fused with the substrate of the nanofiltration super surface element.

In many other embodiments, the other substrate itself has a nanofiltration super surface element disposed on one surface thereof, and wherein the substrate and the other substrate are fused along a surface opposite to the surface on which the associated nanofiltration super surface element is disposed.

In many other embodiments, the fusion method uses a bonding process with a thermal budget below 600 ℃.

In many other embodiments, the bonding process is a wafer bonding process using an adhesive selected from the group of optical epoxy, benzocyclobutene, ultraviolet cured polymer, SU8, and plasma activated silicon dioxide film.

In many other embodiments, the method further comprises removing at least a portion of the backside of the at least one substrate prior to fusing.

In many other embodiments, the method further includes forming at least a first nanofiltering super-surface element on a first side of the first substrate and at least a second nanofiltering super-surface element on a first side of the second substrate, and fusing the first substrate and the second substrate together along a side opposite the first side of the substrates using a bonding process having a thermal budget of less than 600 ℃.

In many other embodiments, the plurality of nanofiltration meta-surface features are non-uniform.

In many other embodiments, the plurality of nanofiltration hypersurface features deviate from the ideal shape by a predetermined amount based on the size of the nanofiltration hypersurface features.

In many other embodiments, the nanofiltered super-surface elements are embedded and planarized, and include two layers of nanofiltered super-surface features that are offset from each other by a distance that is less than or of the same order of magnitude as a wavelength of light within a specified operating bandwidth, such that the two layers of nanofiltered super-surface features cooperate to impart a phase shift to incident light.

Various embodiments are directed to methods of forming a multi-nanofiltered supersurface element, including forming at least a first nanofiltered supersurface element on a first side of a first substrate and at least a second nanofiltered supersurface element on a first side of a second substrate, and fusing the first and second substrates together along an opposite side from the first side of the substrates using a bonding process having a thermal budget of less than 600 ℃.

In various other embodiments, the bonding process is a wafer bonding process using an adhesive selected from the group of optical epoxy, benzocyclobutene, ultraviolet cured polymer, SU8, and plasma activated silicon dioxide film.

In various other embodiments, the method further comprises removing at least a portion of the backside of one or both substrates prior to fusing.

In various other embodiments, the method further comprises:

embedding and planarizing at least one of the first and second nanofiltered supersurface elements;

forming at least a third nanofiltering super-surface element on the first side of the third substrate; and is

The opposite side of the first side of the third substrate is fused with the planarized first or second nanofiltration material using a bonding process with a thermal budget below 600 ℃.

In various other embodiments, planarizing further includes embedding at least one of the first and second nanofiltered ultra-surface elements in one of a polymer or a solid binder.

In various other embodiments, the method further comprises repeating the steps of forming, embedding, and fusing to form a layered stack of four or more nanofiltered super surface elements.

In various other embodiments, the method further comprises:

interposing a spacer substrate between the first and second substrates on a side opposite the nanofiltering super-surface elements, the spacer substrate having at least one aperture disposed therethrough; and is

The spacer substrate is fused to the first and second substrates using a bonding process having a thermal budget below 600 ℃ such that the at least one hole forms an air gap between the first and second substrates.

In various other embodiments, the spacer substrate is formed of a low refractive index material selected from the group of polymers, silicon dioxide, and glass.

In various other embodiments, the spacer material is coated with black chrome.

In various other embodiments, the method further comprises repeating the forming, inserting, and fusing steps to form a layered stack of three or more nanofiltered super surface elements.

In various other embodiments, the plurality of nanofiltration hypersurface features are non-uniform.

In various other embodiments, the plurality of nanofiltration hypersurface features deviate from the ideal shape by a predetermined amount depending on the size of the nanofiltration hypersurface features.

Further embodiments are directed to methods of forming composite nanofiltered supersurface elements, including forming two layers of nanofiltered supersurface features on top of a substrate, wherein the two layers are offset from each other by a distance less than or on the same order of magnitude as a wavelength of light within a specified operating bandwidth, such that the two layers of nanofiltered supersurface features cooperate to impart a phase shift to incident light.

Additional embodiments are directed to methods of forming a nanofiltered supersurface element, comprising:

several embodiments are directed to a nanofiltering super surface element, comprising:

an array of nano-filter super-surface features disposed on top of a substrate, the substrate being transparent to light over a specified operating bandwidth, the array comprising a plurality of nano-filter super-surface features having a feature size smaller than a wavelength of light within the specified operating bandwidth and configured to impart a phase shift to incident light within a plane of the plurality of nano-filter super-surface features;

wherein the plurality of nano-filter super-surface features are non-uniform and deviate from the ideal shape by a predetermined amount based on a size of the nano-filter super-surface features.

In several other embodiments, the ideal shape is a square, and wherein the ideal square has a side length of less than 200nm, the nanofiltration hypersurface feature is formed as a circle, and wherein the ideal square has a side length of less than 300nm, the nanofiltration hypersurface feature is formed as a square with rounded edges.

In many other embodiments, the plurality of nano-filtered super surface features on at least the first or second nano-filtered super surface elements are configured to have asymmetric cross sections and are disposed at least two different rotational angles such that the nano-filtered super surface elements are configured to imprint at least two patterns on the illumination source that have orthogonal polarizations and are linearly offset from each other, or to detect such patterns from incident light prior to illuminating the sensor elements, the array configured such that the array obtains three-dimensional information from the scene in a single shot.

In many other embodiments, the illumination source is polarized or unpolarized and is selected from the group consisting of a VCSEL, a solid state laser, a quantum cascade laser, an LED, and a superluminescent LED.

In many other embodiments, these two patterns are unique.

In many other embodiments, the two patterns have at least 50,000 composite points.

In many other embodiments, at least the first pattern is configured to obtain a measure of the foreground of the scene, and wherein at least the second pattern is configured to obtain a measure of the background of the scene.

In many other embodiments, the two patterns are diagonally polarized with respect to the laser polarization.

In many other embodiments, more than two patterns with more than two different polarizations are used.

Various embodiments relate to a sensor supporting a nanofiltered supersurface component, comprising:

at least one sensor element;

at least one first nanofiltered supersurface element and at least one second nanofiltered supersurface element disposed at an offset distance above the at least one sensor element and having a first spacer layer disposed therebetween;

wherein each of the at least one first and second nanofiltration supersurface elements comprises an array of nanofiltration supersurface features disposed on top of at least one substrate, the substrate being transparent to light over a specified operating bandwidth, the array comprising a plurality of nanofiltration supersurface features having a characteristic dimension smaller than a wavelength of light within the specified operating bandwidth and being configured to impart a phase shift to incident light within a plane of the plurality of nanofiltration supersurface features; and is

Wherein the array of nanofiltration supersurface features on each of the at least one first and second nanofiltration supersurface elements is configured to concentrate light of a specified operating bandwidth over a specific field of view and to shift incident light such that it illuminates the sensor element with a critical ray angle of zero degrees or close to zero degrees.

In various other embodiments, the first spacer layer is one of a solid spacer material or an air gap.

In various other embodiments, the field of view is ± 44 degrees.

In various other embodiments, the sensor further comprises a narrow bandwidth filter disposed between the nanofiltered ultra-surface component and the sensor element.

In various other embodiments, the narrow bandwidth filter is comprised of alternating layers having low and high refractive indices selected from the group consisting of silicon dioxide, titanium dioxide, amorphous silicon, silicon nitride, and aluminum oxide.

In various other embodiments, the sensor further includes a plurality of identical microlenses disposed between the nanofiltered super surface component and the sensor element.

In various other embodiments, the at least one first nanofiltration super surface element and the at least one second nanofiltration super surface element are arranged on opposite sides of the same substrate, and wherein the substrate comprises a first spacer layer.

In various other embodiments, the two nanofiltration super surface elements on either side of the substrate have the same height.

In various other embodiments, the two nanofiltration super surface elements are formed by films simultaneously deposited on the front and back surfaces of the same substrate using a conformal deposition process selected from pressure chemical vapor deposition and atomic layer deposition.

In various other embodiments, the at least one first nanofiltration hyper-surface element and the at least one second nanofiltration hyper-surface element are arranged to face each other inwardly on the substrate formed by the air gap.

In various other embodiments, the sensor further comprises an optical bandpass filter integrated into an outward facing surface of the substrate of the at least one second nanofiltration material.

In various other embodiments, the sensor further includes at least a third nano-filtered super surface element disposed between the first and second nano-filtered super surface elements and the sensor and configured to angularly diverge the path of the incident light such that the light impinging on the sensor has a non-zero primary beam angle.

In various other embodiments, the at least three nanofiltration materials are configured to minimize grid distortion to less than 5% over a specified field of view.

In various other embodiments, the sensor element is a sensor.

Many embodiments relate to a method for fabricating a nanofiltered super surface element for imprinting a desired far field intensity on an illumination source, the method comprising:

calculating a far field of an illumination source;

calculating a target far field, wherein the target is a nanometer filtering super surface element;

calculating a least squares fit to the target far field to obtain a pseudo far field such that a convolution of the pseudo far field and the illumination source far field produces the target far field;

setting the initial nano-filtering super-surface feature array grid and the phase as initial conditions;

determining one or more target cost function cost functions and calculating a gradient function for each of the one or more cost function cost functions for each of a plurality of pixels of the nanofiltered super surface element;

inputting results from the one or more cost functions and the gradient function into an optimization algorithm;

updating the phase of each of the plurality of pixels of the nanofiltering super-surface element and repeating the gradient calculation and optimization until the target cost function converges; and is

And outputting the calculated phase profile of the nano-filtering super surface element.

In many other embodiments, the cost function is selected from the group consisting of squared distance from the target, nearest neighbor distance, squared error of far field projection of the nanofiltered super-surface element under illumination, and computed smoothness of the far field.

In many other embodiments, the optimization algorithm is one of a conjugate gradient or L-Broyden-Fletcher-Goldfarb-Shannon.

Several embodiments are also directed to methods of forming a nanofiltration supersurface element on a substrate, the substrate comprising a plurality of nanofiltration supersurface features having a feature size smaller than a wavelength of light within a specified operating bandwidth and configured to impart a phase shift to incident light within a plane of the plurality of nanofiltration supersurface features, wherein the substrate has a substrate thickness that is unsuitable for use with a target optical system, and further comprising at least one of:

In several other embodiments, the other substrate itself has a nanofiltration super surface element disposed on one surface thereof, and wherein the substrate and the other substrate are fused along a surface opposite to the surface on which the associated nanofiltration super surface element is disposed.

In several other embodiments, the fusion method uses a bonding process with a thermal budget below 600 ℃.

In several other embodiments, the bonding process is a wafer bonding process using an adhesive selected from the group of optical epoxy, benzocyclobutene, ultraviolet cured polymer, SU8, and plasma activated silicon dioxide film.

In several other embodiments, the method further comprises removing at least a portion of the backside of one or both substrates prior to fusing.

In several other embodiments, the method further comprises forming at least a first nanofiltering super-surface element on a first side of the first substrate and at least a second nanofiltering super-surface element on a first side of the second substrate, and fusing the first substrate and the second substrate together along a side opposite the first side of the substrates using a bonding process having a thermal budget below 600 ℃.

In several other embodiments, the plurality of nanofiltration meta-surface features are non-uniform.

In several other embodiments, the plurality of nanofiltration hypersurface features deviate from the ideal shape by a predetermined amount based on the size of the nanofiltration hypersurface features.

In several other embodiments, the method further comprises:

In several other embodiments, planarizing further includes embedding at least one of the first and second nanofiltered ultra-surface elements in one of a polymer or a solid binder.

In several other embodiments, the method further comprises repeating the forming, embedding, and fusing steps to form a layered stack of four or more nanofiltered super surface elements.

In several other embodiments, at least one layer at one end of the layered stack is one of an illuminator or a sensor.

In several other embodiments, the method further comprises:

interposing a spacer substrate between sides of the first and second substrates opposite the nanofiltration super surface elements, the spacer substrate having at least one aperture disposed therethrough; and is

Additional embodiments and features are set forth in part in the description which follows and, in part, will become apparent to those skilled in the art upon examination of the specification or may be learned by practice of the disclosure. A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings, which form a part of the disclosure.

Drawings

The description will be more fully understood with reference to the following drawings, which are presented as exemplary embodiments of the invention and which should not be construed as a complete description of the scope of the invention, wherein:

1A-1G provide diagrams illustrating a fabrication process of a nanofiltered super surface element according to an embodiment of the present invention;

FIG. 2A provides a diagram illustrating an embedded nanofiltered super surface element with an anti-reflective coating according to an embodiment of the present invention;

fig. 2B provides a diagram illustrating a planarized embedded nanofiltered super surface element with an anti-reflective coating according to an embodiment of the present invention;

fig. 3A-3C provide schematic embodiments illustrating a process of fabricating a nanofiltering super surface element according to an embodiment of the present invention;

FIGS. 4A through 4C provide schematic diagrams illustrating nanofiltered super surface elements with varying cross-sectional features according to embodiments of the present invention;

FIG. 5 provides a schematic diagram illustrating a combination of multiple substrates with nanofiltered super surface elements according to an embodiment of the present invention;

FIG. 6 provides a schematic diagram illustrating the combination of multiple substrates with multiple nanofiltered super surface elements according to an embodiment of the present invention;

FIG. 7 provides a schematic diagram illustrating the combination of a plurality of substrates with a plurality of nanofiltered super surface elements, wherein the nanofiltered super surface elements contain air gaps, according to an embodiment of the present invention;

fig. 8A provides a schematic diagram illustrating a super surface element comprising spacers integrated with sensor/light emitter components according to an embodiment of the invention;

fig. 8B provides a schematic diagram illustrating a super surface element including spacers according to an embodiment of the invention;

FIG. 9 provides a schematic diagram illustrating a multi-nanofiltered super surface element substrate according to an embodiment of the present invention;

FIG. 10A provides a schematic illustration of the use of a supersurface element to generate arbitrary radiation patterns from a VCSEL or VCSEL array plus desired results according to embodiments of the present invention;

10B and 10C provide schematic diagrams illustrating the phase (10B) and intensity (10C) obtained using the process of FIG. 10A, according to an embodiment of the present invention;

FIG. 11 provides a schematic diagram illustrating an array nanofiltration super surface element in combination with a set of pixelated sensor elements or illumination sources integrated with a second nanofiltration super surface into an integrated package, according to an embodiment of the present invention;

12A-12C provide schematic diagrams illustrating polarization splitting nanofiltration super surface elements that generate two unique radiation patterns from a VCSEL array according to embodiments of the present invention;

fig. 13 provides a schematic diagram illustrating two nanofiltration super surface elements in combination with a second element such as a cut-off filter, wherein the chief ray angle of the focused light is 0 degrees with respect to the filter plane, according to an embodiment of the present invention; and

fig. 14 provides a schematic diagram illustrating a two nanofiltration super surface element system according to an embodiment of the present invention, wherein each nanofiltration super surface element is formed on a unique substrate.

Detailed Description

Turning now to the drawings, there are provided nanofiltered supersurface elements, integrated systems combining such nanofiltered supersurface elements with light sources and/or detectors, and methods of making and operating such optical arrangements and integrated systems. Many embodiments relate to systems and methods for integrating transmissive nanofiltering super surface elements with other semiconductor devices or other nanofiltering super surface elements, and more particularly to the integration of such nanofiltering materials with substrates, illumination sources and sensors. In some embodiments, the nanofiltered supersurface elements can be used to shape the output light from the illumination source or collect light reflected from the scene to form two unique patterns using polarization of the light. In such embodiments, the shaped emission and collection may be combined into a single, co-designed detection and sensing optical system.

In many embodiments, the nanofiltration super surface element may comprise a multilayer nanofiltration super surface element comprising a combination of two or more nanofiltration super surface optical elements. In various such embodiments, the multi-layer nanofiltered super surface elements may be self-contained (i.e., not directly integrated into the system with a particular illuminator or sensor). In some such embodiments, the optical system may be comprised of a single physical component or substrate having the nanofiltered supersurface elements disposed on either side thereof. In some embodiments, multiple substrates with multiple nanofiltered super surface elements may be combined to create more complex systems. In such embodiments, the thickness of the substrate may be determined by the requirements of the optical system, manufacturing constraints, and the specific design of the two nanofiltration materials. In various embodiments, the multilayer nanofiltering super surface elements may be formed by patterning each individual nanofiltering super surface element on a unique substrate, and then fusing the substrates together by a suitable technique (e.g., wafer bonding, optical adhesive). In general, however, any number of nanofiltered supersurface elements may be combined through any number of steps using CMOS or related processes, depending on the embodiment.

In many embodiments, the nanofiltered super surface elements may be freestanding or may be embedded in another material. In various such embodiments, the choice of embedding material includes appropriate choices of refractive index and absorption characteristics. In many such embodiments, the embedding material may provide mechanical stability and protection as well as additional design freedom, which enables the nanofiltration material to perform a desired optical function.

In various embodiments, the nanofiltered super surface elements can be mounted or fabricated directly on the LED, VCSEL face, or each face of the VCSEL in the array to minimize device thickness and optimize the nanofilter-illuminator/sensor alignment. In some such embodiments, the resulting system may be used to convert a natural lambertian light distribution or some arbitrary light distribution into a wide range and substantially arbitrary light distribution, including, for example, a so-called top hat (top hat), a so-called batwing contour (bat-wing), or any other desired structured light pattern.

In some embodiments, a spacer layer of defined thickness (e.g., working distance) may be deposited over CMOS image sensors, LEDs, VCSELs, etc. to achieve an optical distance suitable for a desired camera design, illuminator design, or optimal system performance. In various such embodiments, the spacer layer material may be organic or inorganic and may have a lower index of refraction than the dielectric element comprising the nano-filter metamaterial material. In some such embodiments, the thickness of the spacer layer may be modified to provide a suitable optical spacing for a particular optical system.

Various embodiments also relate to methods of making nanofiltered super surface elements. In some such embodiments, the method involves fabricating the super-surface elements on a wafer containing other devices (e.g., sensors or light emitters), thereby avoiding expensive fabrication processes (e.g., mechanical assembly of small-sized elements or active alignment of optical elements with sensors) in some embodiments. In some such embodiments, the nanofiltered super surface elements may be integrated with the sensor (or light emitter) in a series of operations in a semiconductor factory.

Examples for the production of nanofiltered super surface elements

The fabrication of nanofiltration super surface elements currently requires the use of specialized processes and systems that are not compatible with large scale fabrication, thereby limiting the implementation and adoption of such nanofiltration super surface elements in CMOS devices. The ability to produce a nanofiltration meta-surface by standard semiconductor processes would enable direct integration of the nanofiltration meta-surface optical elements with functional elements, such as Light Emitting Diodes (LEDs), Vertical Cavity Surface Emitting Lasers (VCSELs), Complementary Metal Oxide Semiconductor (CMOS) image sensors, micro-electromechanical (MEMs) devices, etc., where direct integration means combining the nanofiltration meta-surface elements with the sensors/light emitters using the same or similar unit processes as those used to fabricate the functional CMOS elements.

Accordingly, many embodiments relate to methods of fabricating nanofiltered supersurface elements and systems, and more particularly to methods that can be implemented in conventional semiconductor fabrication facilities. In various embodiments, conventional processes suitable for fabricating nanofiltered super surface elements may include photolithography, nanoimprint, various Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD) and Physical Vapor Deposition (PVD) mass transfer processes for this application, chemical and plasma etching (and CMC), and the like. Turning to the figures, an exemplary set of manufacturing processes tailored for the manufacture of various aspects of embodiments of nanofiltered supersurface elements is presented in the schematic diagrams of fig. 1-1G.

The nano-filter super-surface optical element is composed of a dielectric having a characteristic size from 10 nm to micron-scale, or generally smaller than the wavelength of light of a subject of use of the nano-filter super-surface. Referring to fig. 1A-1C, in many embodiments, an initial step of fabricating the nanofiltered super surface element includes patterning and forming an array of nanofiltered super surface features. In many such embodiments, as shown in FIG. 1A, the super-surface feature formation process is achieved by depositing a patterned material 14 on top of a suitable hard mask material 12 of thickness t (t being the thickness of the film and the height of the final nanofiltered super-surface), where the hard mask material 12 itself is disposed atop a suitable substrate 10. These layers may be formed using any suitable deposition technique, including, for example, sputtering, Chemical Vapor Deposition (CVD), or Atomic Layer Deposition (ALD).

Although exemplary materials will be discussed with respect to specific embodiments throughout this disclosure, it should be understood that any suitable combination of patterning materials, hard mask materials, and substrates may be used for these purposes. For example, in various embodiments, the substrate material is selected to provide suitable structural support and to be transparent to light over a desired bandwidth. Exemplary substrate materials successfully implemented using the methods described in the embodiments include, for example, fused silica, sapphire, borosilicate glass, and rare earth oxide glass. Similarly, the hard mask material may be selected from any readily available material suitable for use in a semiconductor manufacturing facility. Exemplary hard mask materials include, for example, silicon, various stoichiometric silicon nitrides, silicon dioxide, titanium dioxide, aluminum oxide, and the like.

In particular, as shown in FIG. 1B, once the substrate 10, hard mask material 12, and patterning material 14 (with the layers in place as described above in FIG. 1A, the patterning material is patterned to reproduce a feature array pattern 16, the feature array pattern 16 corresponding to either a negative reproduction or a positive reproduction of the final desired nanofiltered super surface feature array structure.

Once the desired feature array pattern 16 (described above in fig. 1B) is in place, an anisotropic etch process is used to transfer the desired feature pattern into the hard mask material layer 12, as shown in fig. 1C. An exemplary anisotropic etch process used in accordance with an embodiment is a reactive ion etch process. It should be understood that many possible chemistries may be used in the reactive ion etching process, including, for example, SF6 gas, Cl2 gas, BCl3 gas, C4F8 gas, or any mixture of these gases.

As shown in fig. 1D, where a particular nanofiltering super surface material is used in the final nanofiltering super surface element, the feature array pattern 16 (as described above in fig. 1C) formed in the etched hard mask material 12 can serve as a template for the final nanofiltering super surface structure. In such an embodiment, a separate nanofiltered superface material 18 is deposited using a suitable conformal coating process (e.g., Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), etc.) to fill the mask stock and create the nanofiltered superface elements. As shown, the nano-filter meta-surface material 18 overfills the spaces formed by the etched feature array pattern 16 in the hard mask material 12 to completely fill the voids. In addition to filling the voids 20, the process leaves a blanket layer of nano-filter meta-surface material over the remaining hard mask. Also, although specific nano-filter meta-materials will be discussed throughout, it should be understood that nano-filter meta-materials according to embodiments may be selected from any readily available dielectric material having a desired index of refraction and suitable for use in a semiconductor fabrication facility.

Referring to fig. 1E, once the overfilled nanofiltration meta-surface material 18 is deposited, etching or chemical mechanical planarization may be performed to remove the overfill layer, according to an embodiment, to provide a consistent height for the patterned hard mask 12 and the nanofiltration meta-surface material 12. In embodiments where an embedded nanofiltering superfinish material is desired and a suitable hard coat material has been selected as the embedding material (as previously described), the process can be stopped and the resulting nanofiltering superfinish material embedded in the hard coat material structure used as the final nanofiltering superfinish component. The nanofiltered super surface element may then optionally be coated with a suitable AR coating or mechanical protective layer, as described below.

In various embodiments, as shown in FIG. 1E, the hard mask material 12 is removed, leaving behind the free-standing nanofiltered ultra-surface element 20. In such embodiments, the hard mask may be removed using a selective etch chemistry that etches the hard mask material 12 at a much higher rate (e.g., 100: 1 or 1000: 1 or higher) than the nanofiltration meta-surface material 18). As will be appreciated by those skilled in the art, such a process depends on the particular selection of the nanofiltration superficies material and the hard mask material.

Finally, as previously mentioned, in certain embodiments where it is desirable for the nanofiltration super surface material to have an AR coating or mechanical protective layer, additional steps are required to complete the final nanofiltration super surface element. Referring to fig. 1G, in various embodiments, an AR coating or mechanical protection or planarization layer 24 may also be deposited to fill the voids 22 between the nanofiltration meta-surface features 20 and extend over the surface of the nanofiltration meta-surface material layer 18. It should be understood that any material having optical properties suitable for a particular optical system design may be used in the process, for example, a suitable refractive index and minimal light absorption at a desired wavelength or bandwidth of interest (the planarization layer may allow for a multi-order nanofiltered supersurface element for complex optical systems). As described above, to protect the nanofiltration meta-surface and provide improved functionality, in many embodiments, the constituent elements of the nanofiltration meta-surface and the substrate surface are coated in one or more materials or material layers. Referring to FIG. 2A, a diagram of an embedded nano-filter meta-surface is shown. In addition, as described above, the embedding medium itself can potentially be used as an anti-reflective coating.

While certain embedded nanofiltered subsurface embodiments are described above, in various other embodiments, a nanofiltered subsurface can be embedded and planarized, as shown in FIG. 2B. In these embodiments, the nanofiltered super surface elements may be embedded in a suitable low refractive index material (as described above), and in an additional step, the embedding medium 24 is then etched or planarized such that its height is commensurate with the nanofiltered super surface elements 20. An optional anti-reflective coating may also be included on the bare substrate surface 26 or on the patterned nanofiltration surface side (not shown).

Embodiments for fabricating nanofiltered super surface elements on conventional substrates

Although the above discussion has described in detail a manufacturing process that enables the formation of a variety of separate or embedded nanofiltered super surface elements using conventional manufacturing techniques, in practice it is not possible to employ conventional nanofiltered super surface elements to allow for the economical production of nanofiltered super surface elements using existing equipment in a manufacturing plant.

Thus, many embodiments relate to processes for tailoring the fabrication of nanofiltered super surface elements or systems according to the thickness of a particular substrate at which the nanofilter or nanofilter system is being produced.

Referring to fig. 3A-3C, an exemplary process for producing a nano-filtered meta-surface according to using standard substrate thicknesses is provided. As shown, after deposition of the nanofiltration meta-surface material and photolithographic patterning and etching (as shown in fig. 1A to 1G above), if the nanofiltration meta-surface material layer is designed for standard substrate thicknesses, an additional protective layer or AR coating may be provided on the nanofiltration meta-surface material layer before being delivered to further back-end processing. In many such embodiments, back-end processing may include dicing thousands of nanofiltered metasurfaces formed on the substrate using a dicing process.

Embodiments of nanofiltered super surface elements with non-ideal characteristics are fabricated.

In conventional processes for designing a meta-surface, the shape fidelity from the designed nano-filtered meta-surface to the manufactured nano-filtered meta-surface is typically assumed to be one-to-one or to remain within a certain error range. This approach results in a nanofiltration meta-surface array that is typically composed of a single set of shapes, wherein one characteristic of the set of shapes is changed (e.g., circular in shape at the nanofiltration meta-surface and different diameters at the nanofiltration meta-surface). However, manufacturing techniques for potential mass production of nanofilters are generally unable to perform faithful reproduction of certain geometries.

For example, FIG. 4A provides a cross-sectional schematic of an exemplary cross-section of a nanofiltration meta-surface, wherein a set of shapes that are non-uniform are distributed across the nanofiltration meta-surface. In this particular embodiment, a square column shape is desired. However, after fabrication, what is actually formed at a given nanofilter subsurface is an array of the following shapes: squares with different side lengths (e.g., s), squares with rounded corners of varying radius r, and circles with varying radius r or ry. In particular, the larger features here are rounded squares or squares; however, as the side length of the square decreases below a certain minimum side length, the square becomes circular. In a process according to an embodiment, the manufacturing constraints are modeled on each desired nanofiltered super surface feature shape, and these non-ideal or non-uniform feature elements are then used to determine the final nanofiltered super surface element array structure.

For example, fig. 4B and 4C provide variation diagrams illustrating the printed and designed patterns from a nanofiltered super surface element mask reticle. As shown, in an embodiment of the design of a feature with a side length of 200nm and a period of 450nm, the printing fabrication technique will actually replicate a circle with a diameter of 200nm (FIG. 4B). In contrast, for square features having a side length of 296nm and a period of 450nm, the feature fabricated is a square with rounded corners (FIG. 4C). Thus, many embodiments of nanofiltration super surface elements designed with square nanofiltration super surface features may be replaced with rounded square shapes below 300nm and circles below 200nm to allow the use of industry standard CMOS replication technology.

Embodiments for fabricating a plurality of nanofiltered super surface elements

As previously mentioned, various embodiments relate to methods for wafer bonding together two substrates comprising nanofiltered super surface elements. Such embodiments may be modified to allow for easy fabrication of multiple nanofiltration super surface elements, for example, bi-layer and tri-layer structures (e.g., nanofiltration super surface elements comprising two or three separate arrays of nanofiltration super surface features). In particular, although there are many wafer bonding processes, each wafer bonding process imposes a specific thermal budget on the substrates being joined. Since many embodiments of the nanofiltration super surface element use amorphous Si as the nanofiltration super surface material, excessive heating of the substrate can lead to crystallization of Si. Thus, embodiments are presented that allow the formation of bi-and tri-layer structures of the nanofiltration super surface using low temperature processes, for example using UV cured polymers (e.g. benzocyclobutane (BCB) etc.) or plasma activated SiO, in order to allow wafer bonding of two or more nanofiltration super surface elements at low temperatures.

Referring to FIG. 5, a schematic diagram of forming a nano-filter super surface bi-layer structure is shown, according to an embodiment. As shown, in many such embodiments, a plurality of unique nanofiltered

ultra-surface elements

30 and 32 are fabricated on two

different substrates

34 and 36. The nanofiltered super surface elements are then made into a combined system by fusing the bottom of each individual substrate (e.g., the surface portion of the substrate without any nanofiltered super surface elements). As described above, the substrates may be fused by wafer bonding techniques, optical epoxy or any suitable method.

Although the disclosure so far has detailed embodiments that contain only two nanofiltered super surface elements, the process can be generalized to any number of super surface elements. For example, some applications may require three or more nano-filtered metasurfaces to be combined into a monolithic unit. In this case, two substrates comprising separate nanofiltered super surface elements may form an initial uncombined unit.

In embodiments including such spacer substrates, any suitable substrate material may be used. For example, in many embodiments, the spacer substrate may be any low index material, such as a polymer, SiO, glass, or the like. Further, in other embodiments, the spacer material may be coated with black chrome. The super surface elements may also be formed of any material optimized for a particular bandwidth, such as silicon, TiO, alumina, and metals, among others. The nano-filtered super surface elements may also be fabricated using methods such as those described in fig. 1A-1G or using common semiconductor fabrication processes.

The above embodiments describe a process for combining two and three nanofiltration metasurfaces; however, this embodiment can be extended to not just combine two or three nano-filtered metasurfaces. For example, with reference to fig. 5-7, embodiments allow stacking any number of nanofiltered supersurface elements by iterating the steps described above. Referring to FIG. 8A, in various embodiments, a set of

nanofiltration hypersurfaces

80, 82, 84, etc. and spacer layers 86, 88, etc. may be integrated directly with the illuminator or sensor. In such an embodiment, an optional spacer layer 90 is first formed on the sensor/light emitter 92 by a suitable deposition process (alumina, metal, etc.). The nanofiltered super surface elements can be fabricated using the methods described in fig. 1A-1G or using other suitable common semiconductor fabrication processes.

Although the above description assumes integration with the sensor or light emitter 92, it is also possible to iteratively fabricate a set of nanofiltration super surface elements and spacer layers on the substrate 90, as shown in fig. 8B, in such an embodiment the process is as described with respect to fig. 8A of the present application, but rather than integrating the nanofiltration super surface/spacer stack onto the sensor/light emitter 92, the stack is created on a separate substrate 90. The combined substrate and stack according to these embodiments may then be integrated into an optical system or used as a separate optical component.

Surface element of multilayer nanofilter and method for manufacturing the same

Although in the previously detailed embodiments each nano-filtered super surface element is designed to perform a unique optical function in a larger optical system, and the super surface elements are typically separated by a macroscopic distance (a distance of 10 or more wavelengths), in various embodiments a plurality of two layers of patterned material may be provided at a microscopic distance from each other (e.g., at a distance from each other that is less than or on the same order of magnitude as the wavelength of light) such that the layers combine to form a single nano-filtered super surface element performing a single optical function. Any suitable combination of the fabrication steps set forth with respect to fig. 1-8 may be used to form and combine the feature layers.

FIG. 9 provides a schematic diagram illustrating a multi-nanofiltered super surface element substrate according to an embodiment of the present invention.

FIG. 10A provides a schematic illustration of the generation of arbitrary radiation patterns from VCSELs or VCSEL arrays using nano-filtered super surface elements, according to an embodiment of the present invention.

Fig. 10B and 10C provide schematic diagrams illustrating the phase 10B and intensity 10C obtained using the process of fig. 10A, in accordance with an embodiment of the present invention.

FIG. 11 provides a schematic diagram illustrating an array nanofiltration super surface element in combination with a set of pixelated sensor elements or illumination sources integrated with a second nanofiltration super surface into an integrated package, according to an embodiment of the invention.

Fig. 12A to 12C provide schematic diagrams illustrating polarization splitting nanofiltration super surface elements according to embodiments of the present invention, which generate two unique radiation patterns from a VCSEL array.

Fig. 13 provides a schematic diagram illustrating two nanofiltration super surface elements in combination with a second element such as a cut-off filter, wherein the chief ray angle of the focused light is 0 degrees with respect to the filter plane, according to an embodiment of the invention.

Claims

1. A method for fabricating one or more nanofiltered supersurface elements or systems, comprising:

depositing a layer of pattern material on the layer of hard mask material;

patterning the pattern material to form an array pattern on top of the hard mask material layer, the array pattern comprising one of a positive or negative reproduction of an array of nano-filter super-surface features comprising a plurality of nano-filter super-surface features having a feature size smaller than a wavelength of light within the specified operating bandwidth and configured to impart a phase shift to incident light within a plane of the plurality of nano-filter super-surface features;

removing residual pattern material from the top of the hard mask material layer.

2. The method of claim 1, wherein:

the substrate is formed of a material selected from the group consisting of fused silica, sapphire, borosilicate glass, and rare earth oxide glass;

the hard mask material layer is formed of a material selected from the group consisting of silicon, various stoichiometries of silicon nitride, silicon dioxide, titanium dioxide, aluminum oxide, and is disposed using a deposition process selected from the group consisting of sputtering, chemical vapor deposition, and atomic layer deposition;

the pattern material layer is formed of one of a photoresist patterned using a photolithography process or a polymer patterned using a nanoimprint process;

the array pattern is etched using a reactive ion etching process selected from the group consisting of SF6, Cl2, BCl3, C4F8, or any static or multiple mixture thereof; and is

The residual pattern material is removed using a process selected from the group consisting of a chemical solvent, a chemical etchant, and a plasma etchant.

3. The method of claim 1, wherein the patterned hard mask material is a dielectric and forms the nanofiltering super surface features of the nanofiltering super surface elements.

4. The method of claim 1, further comprising:

depositing a dielectric nanofiltration meta-surface material layer on the patterned hard mask material layer such that the nanofiltration meta-surface material layer fills the voids in the hard mask material layer and extends over the raised features of the hard mask material layer, forming a capping layer of nanofiltration meta-surface material on top of the hard mask material layer; and

planarizing the capping layer such that the nano-filter meta-surface material layer and the hard mask material layer terminate at a uniform height above the substrate.

5. The method of claim 4, wherein: the nano-filtered super surface material layer is formed of a material selected from the group consisting of silicon, various stoichiometries of silicon nitride, silicon dioxide, titanium dioxide, aluminum oxide, and is deposited using a conformal process selected from the group of chemical vapor deposition and atomic layer deposition; and the planarization uses a process selected from an etching process selected from the group consisting of wet etching and plasma etching, or a chemical mechanical planarization technique.

6. The method of claim 4, wherein the nanofiltering super-surface material disposed in the voids forms the nanofiltering super-surface features of the nanofiltering super-surface elements, and wherein the hard mask material is configured as an embedding material having a lower index of refraction than the nanofiltering super-surface material at the specified operating bandwidth.

7. The method of claim 6, wherein the hard mask material has negligible absorption over the specified operating bandwidth and a refractive index between 1 and 2.4 over the specified operating bandwidth.

8. The method of claim 4, further comprising: removing the layer of hard mask material using selective etching such that the layer of nanofiltration meta-surface material disposed in the voids of the patterned hard mask remains on the surface of the substrate after removal of the layer of hard mask material to form a plurality of isolated nanofiltration meta-surface features formed by a plurality of air gaps.

9. The method of claim 8, further comprising depositing a layer of embedding material on the isolated nanofiltration meta-surface features such that air gaps between the features are filled and such that the layer of embedding material extends over a surface of the nanofiltration meta-surface material layer, wherein the layer of embedding material has a lower refractive index than the nanofiltration meta-surface material at the specified operational bandwidth.

10. The method of claim 9, wherein the embedding material is polymethylmethacrylate.