A metamaterial is an artificially made material that includes structures of geometric patterns having sub-wavelength dimensions with respect to a targeted electromagnetic spectrum or wavelength. The metamaterial is composed of one or multiple actual materials, such as a combination of metallic and dielectric materials. The subwavelength-scaled structures are distributed on or under the surface layer and can be disposed in one or more layers. The structures may have similar or different geometries and may be repeated and spaced across a layer to alter the behavior of electromagnetic waves, thereby causing an electromagnetic effect. For example, the structures may be separated round or square metal patches that are placed on a dielectric layer, or may be round or square gaps in a metal layer. A metamaterial can be designed to interact with an electromagnetic wave in a certain light spectrum, such as visible or infrared light, to absorb or reflect light at a certain wavelength or frequency.
In accordance with at least one example of the description, an apparatus includes a base layer including a photodiode, shallow trench isolation (STI) structures on the photodiode, and a metamaterial layer on the STI structures and including a metasurface and a dielectric layer.
In accordance with another example of the description, an optical device includes a metamaterial layer configured to absorb a portion of an incident light having a frequency spectrum, the portion of the incident light having a frequency range that is narrower than and within the frequency spectrum of the incident light, a photodiode disposed in a layer coupled to the metamaterial layer and configured to detect an amplitude of the portion of the incident light, and STI structures disposed between the metamaterial layer and the photodiode, the STI structures configured to pass the portion of the incident light within the frequency range from the metamaterial layer to the photodiode.
In accordance with another example of the description, a light detector system includes a light source configured to emit a light beam having a frequency spectrum, and a light detector configured to detect an amplitude of the light beam at the frequency spectrum. The light detector includes a base layer including a photodiode and STI structures on the photodiode, and a metamaterial layer on the STI structures and including a metasurface and a dielectric layer.
Optical or light detectors, which may also be referred to as optical sensors, are types of devices that detect light at a specific frequency or light wavelength range. The detection includes absorbing a portion of incident light and converting it into a signal, such as an electrical signal, which can be measured and analyzed. Analysis of the measured electrical signal is useful to infer the characteristics of a sample exposed to the light. The collected signal data is useful to infer characteristics of the sample, such as the type, composition or density of materials in the sample. For example, optical detectors can serve as gas or fluid detectors in conjunction with various light sources and frequency spectrum, such as infrared, visible light or ultraviolet laser sources. Optical detectors may include various materials and layers designed for specific detection applications.
The possibility of designing metamaterials to control light and the manufacturing processes involved in manufacturing such structures may render metamaterials suitable for making optical devices. An optical detector may include a metamaterial engineered according to the optical device application. This may involve the metamaterial selecting or filtering a certain wavelength or range of wavelengths of incident light toward the detector and reflecting other wavelengths away from the detector. Metamaterial design includes determining the number of geometric patterns of the metamaterial structures, and the size and spacing of the geometric patterns at each layer, which can be arranged into stacked two-dimensional (2D) arrays. To achieve detection, the metamaterial may be combined with active devices, such as photodiodes on a substrate, which may be a silicon or other form of substrate.
The metamaterial may also be combined with other materials and layers that may be stacked to achieve increased light absorption at designed wavelengths. For example, dielectric layers may be overlaid on the metamaterial to form an anti-reflection coating (ARC) that may increase the absorption of light. The thickness and materials of the ARC can be selected to increase light absorption around the same wavelengths of light absorption of the metamaterial. The ARC may also be disposed between the metamaterial and the photodiodes. However, adding ARC layers to the optical detector device can present difficulties in the manufacturing process. The deposition of dielectric layers may involve different and additional manufacturing processes, which may add manufacturing cost and time. Also, such ARC implementation can be sensitive to variations in the manufacturing process, where variations of layer thickness, while within a manufacturing margin of error, can result in degradation in light absorption of the optical detector.
This description provides various examples of combining one or more metamaterial layers with photodiodes to achieve increased light filtering and absorption for optical detectors. The absorption can be increased by adding STI structures between the metamaterial layers and the photodiodes. The STI structures may provide isolation between adjacent photodiodes to mitigate electric current leakage. The STI structures may also form an ARC layer providing increased absorption of light from the metamaterial layers into the photodiodes. The STI structures can be added to the optical device via the same manufacturing process as other components of the optical device, and may be less sensitive to manufacturing variations and errors than other ARC solutions.
Light filtering and absorption can be further increased by adding a mold compound or layer on the metamaterial layers during a packaging process of the optical device. The mold compound can be designed to let light wavelengths covering or matching the filter range of the metamaterial through the optical detector and reject wavelengths outside that range. For example, for ambient or visible light optical detectors, the metamaterial may be designed to achieve light absorption in the visible spectrum and the mold compound may be designed to reject infrared light. Accordingly, the absorbed visible light may reach the photodiodes with reduced infrared radiation.
The metamaterial 225 may include one or more metasurfaces 240 embedded in one or more dielectric layers 242 of the metamaterial 225. Each metasurface 240 may form a layer of one-dimensional (1D) or two-dimensional (2D) arrays of structures disposed across the same layer. For example, the metasurface 240 may include a grid of metal patches equally spaced in the dielectric layer 242. The structures of the multiple metasurfaces 240 may have patterns of different geometries, sizes, and spacing. The spacing of the structures may determine the filtering and ARC properties of the metasurface 240 and accordingly the metamaterial 225. The metal patches may have various geometries, such as square, round, slit, or cross patterns. In another example, the metasurface 240 may include a grid of equally spaced gaps in a metal sheet or layer. The gaps may be empty space, may be filled with a dielectric or other material, or a combination thereof.
The base layer 235 may include STI structures 250 disposed on a photodiode layer 260. The STI structures 250 and the photodiode layer 260 may be embedded in one or more semiconductor layers 270 of the base layer 235. The STI structures 250 may be trenches formed in the semiconductor layer 270 and filled with another material, which may be a dielectric. The photodiode layer 260 may include multiple photodiodes arranged in an array or grid. The STI structures 250 may be aligned on the photodiodes to cause isolation and prevent electric current leakage between the photodiodes. The photodiodes may absorb the light and convert the light energy into electrical energy in the form of a detected voltage or electrical signal. The metamaterial 225 may be positioned between the base layer 235 and the mold layer 210. The mold layer 210 may be a substantially transparent dielectric substrate that allows the incident light to pass through toward the metamaterial 225 and provide protection for the other layers.
To increase the absorption of incident light in the optical device 200 at a wavelength or frequency range, the metamaterial 225 may be designed for both filtering and ARC properties. The materials of the components of the metamaterial 225 and the spacing of the structures in the metasurfaces 240 may be designed to increase light filtering toward the photodiode layer 260 in a wavelength range, and to reflect light away from the photodiode layer 260 outside that wavelength range. The shape of the structures and/or the number of metasurfaces 240 and dielectric layers 242 in the metamaterial 225 may be designed to further increase light absorption and to narrow or widen the wavelength range. Increasing the light absorption property of the metamaterial 225 provides the ARC function, and designing the wavelength range for such absorption provides the filtering function of the metamaterial 225. The STI structures 250 may also be designed to match the ARC properties of the metamaterial 225. For example, the material, the size and/or the depth, which may also be referred to as the thickness, of the STI structures 250 may be designed to increase light filtering toward the photodiode layer 260 in the absorption wavelength range of the metamaterial 225. The mold layer 210 may also be designed to match the filtering and ARC properties of the metamaterial 225, such as based on the thickness and the material composition of the mold layer 210.
As described above, the filtering and ARC properties of the metamaterial 225 may depend on the materials of the metamaterial 225 and the spacing of the structures in the grid, as well as on the dimensions of the structures. Therefore, the materials of the structures and the dielectrics, and the spacing of the structures, may be designed to select the wavelength range for light absorption. The structure dimensions, including the width and thickness of the structures, may be designed to tune the filtering and ARC properties of the metamaterial 225, based on the materials and spacing. For example, to achieve light absorption in the infrared spectrum within a narrower wavelength range in that spectrum, the spacing of the metal patches in a metasurface 240 may be about 100 micrometers (µm) and the metasurface 240 or structure thickness may be about 10 µm. In the case of light absorption in the visible spectrum, the spacing may be in the sub-micron region (< about 1 µm) and the thickness of the structure may be less than about 0.01 µm.
The base layer design 630 is useful for the base layer 235 of the optical device 200 to increase the ARC effect. The base layer design 630 includes STI structures 650 that may be arranged in a 2D array on a photodiode layer 630. The material, spacing, and thickness of the STI structures 650 may be designed to increase the filtering of light from the metamaterial to the photodiodes in the filter wavelength range of the metamaterial. The base layer design 630 may also include a dielectric layer material in which the photodiode layer 635 may be disposed. The mold layer design 610 is useful for the mold layer 210 of the optical device 200 to increase the filtering and ARC effects of the metamaterial. In some examples, the mold layer design 610 includes a thickness and material of the mold layer 210 on the metamaterial designed to increase light absorption within the filter wavelength range of the metamaterial design 625.
The metamaterial layer 1101 may include a metal patch 1106 embedded in an inter-metal dielectric layer of organosilicate glass (IMD OSG) 1107. The metamaterial layer 1101 may also include a silicon carbon nitride (SiCN) layer 1108 disposed on the IMD OSG 1107, and a silicon oxycarbide (SiCO) layer 1109 disposed on the SiCN layer 1108. The thickness of the metal patch 1106 and the IMD OSG 1107 may be about 140 nm with up to about 50 nm variation. The thickness of the SiCO layer 1109 and the SiCN layer 1108 may be about 40 nm with up to about 4 nm variation. The metamaterial layer 1101 may also be disposed on a second SiCO layer 1110 provided via the same manufacturing process 1102.
The manufacturing process 1102 that forms the layers described above (e.g., the first manufacturing process) may be a process capable of forming relatively thin layers with high accuracy. Such layers may be disposed on thicker layers of the optical device 1100. The thicker layers may be formed by a second less controlled or stringent manufacturing process 1111with less manufacturing accuracy and more thickness variation. The thicker layers may include an interlevel dielectric (ILD) layer 1112, and a thicker metal patch 1113 embedded in a thicker IMD layer 1114 on the ILD layer 1112. The thickness of the ILD layer 1112 may be about 600 nm with up to about 140 nm variation. The thickness of the metal patch 1113 may be about 613 nm with up to about 69 nm variation, and the thickness of the thicker IMD layer 1114 may be about 1113 nm with up to about 186 nm variation.
The processor 1301 may be configured to read and execute computer-readable instructions. For example, the processor 1301 may be configured to invoke and execute instructions stored in the memory 1304, including the instructions 1305. The processor 1301 may support one or more global systems for wireless communication. Responsive to the processor 1301 sending a message or data, the processor 1301 drives or controls the transceiver 1302 to perform the sending. The processor 1301 also drives or controls the transceiver 1302 to perform receiving, responsive to the processor 1301 receiving a message or data. Therefore, the processor 1301 may be considered as a control center for performing sending or receiving, and the transceiver 1302 is an executor for performing the sending and receiving operations.
In an example, the memory 1304 may be coupled to the processor 1301 through the bus 1390 or an input/output port. In another example, the memory 1304 may be integrated with the processor 1301. The memory 1304 is configured to store various software programs and/or multiple groups of instructions, including instructions 1305. For example, the memory 1304 may include a high-speed random-access memory, and may further include a nonvolatile memory such as one or more disk storage devices, a flash memory, or another nonvolatile solid-state storage device. The memory 1304 may store an operating system such an operating system such as ANDROID, IOS, WINDOWS, or LINUX. The memory 1304 may further store a network communications program. The network communications program is useful for communication with one or more attached devices, one or more user equipments, or one or more network devices, for example. The memory 1304 may further store a user interface program. The user interface program may display content of an application through a graphical interface, and receive a control operation performed by a user on the application via an input control such as a menu, a dialog box, or a physical input device (not shown). The memory 1304 may be configured to store the instructions 1305 for implementing the various methods and processes provided in accordance with the various examples of this application.
The antenna 1303 may be configured to convert electromagnetic energy into an electromagnetic wave in free space, or convert an electromagnetic wave in free space into electromagnetic energy in a transmission line. The transceiver 1302 may be configured to transmit a signal that is provided by the processor 1301, or may be configured to receive a wireless communications signal received by the antenna 1303. In this example, the transceiver 1302 may be considered a wireless transceiver.
The hardware architecture 1300 may also include another communications component such as a Global Positioning System (GPS) module, a BLUETOOTH module, or a WI-FI module. The hardware architecture 1300 may also support another wireless communications signal such as a satellite signal or a short-wave signal. The hardware architecture 1300 may also be provided with a wired network interface or a local area network (LAN) interface to support wired communication.
In accordance with various examples, the hardware architecture 1300 may further include an input/output device (not shown), an audio input/output device, a key input device, a display, and the like. The input/output device may be configured to implement interaction between the hardware architecture 1300 and a user/an external environment, and may include the audio input/output device, the key input device, the display, and the like. The input/output device may further include a camera, a touchscreen, a sensor, and the like. The input/output device may communicate with the processor 1301 through a user interface.
It should be noted that the hardware architecture 1300 shown in
The term “couple” is used throughout the specification. The term may cover connections, communications, or signal paths that enable a functional relationship consistent with this description. For example, if device A provides a signal to control device B to perform an action, in a first example device A is coupled to device B, or in a second example device A is coupled to device B through intervening component C if intervening component C does not substantially alter the functional relationship between device A and device B such that device B is controlled by device A via the control signal provided by device A.
A device that is “configured to” perform a task or function may be configured (e.g., programmed and/or hardwired) at a time of manufacturing by a manufacturer to perform the function and/or may be configurable (or re-configurable) by a user after manufacturing to perform the function and/or other additional or alternative functions. The configuring may be through a construction and/or layout of hardware components and interconnections of the device, or a combination thereof.
A device that is described herein as including certain components may instead be adapted to be coupled to those components to form the described device. For example, a structure described as including one or more elements (such as structures or layers) and/or one or more sources (such as voltage and/or current sources) may instead include only the elements within a single physical device (e.g., the structures and layers in the device) and may be adapted to be coupled to at least some of the sources to form the described structure or system either at a time of manufacture or after a time of manufacture, for example, by an end-user and/or a third-party.
While certain components may be described herein as being of a particular process technology, these components may be exchanged for components of other process technologies. Structures and designs described herein are reconfigurable to include the replaced components to provide functionality at least partially similar to functionality available prior to the component replacement.
Unless otherwise stated, “about,” “approximately,” or “substantially” preceding a value means +/- 10 percent of the stated value. Modifications are possible in the described examples, and other examples are possible within the scope of the claims.