This invention relates to integrated circuits comprised of semiconductor devices such as transistors, diodes, resistors, capacitors, inductors, lasers and the like that form the basis of modern electronics.
In conventional silicon chip manufacturing, a planar silicon wafer is coated with a photoresist. The desired semiconductor patterns are produced on a planar photomask. Light is beamed at the photomask such that the pattern is projected onto the photoresist layer. This pattern hardens into an exact representation of the photomask when it is developed. Etching then removes selective areas of the pattern using a plasma that reacts to the material not covered by the hardened photoresist.
The limited space on the planar surface of the silicon wafer limits the number of circuits that can be created on the planar surface.
An integrated circuit comprises a silicon cylinder having a sidewall upon which a plurality of semiconductor devices have been printed, one or more electrical leads electrically connected to each semiconductor device, and a plurality of radial wiring interconnects projecting outward from the sidewall.
At least some of the electrical leads may terminate at a bottom edge of the sidewall.
One or more of the electrical leads may terminate at a corresponding one of the radial wiring interconnects, enabling three dimensional integration.
Alternative embodiments of the invention comprise a method of manufacturing an integrated circuit. The method comprises printing a plurality of semiconductor devices on a sidewall of a silicon cylinder and slicing the silicon cylinder into a plurality of thinner silicon cylinders. Each thinner silicon cylinder has a plurality of semiconductor devices printed on its sidewall.
Printing a plurality of semiconductor devices on a sidewall of a silicon cylinder may comprise placing a concentric photomask in a position surrounding at least a portion of the silicon cylinder and projecting light from outside the concentric photomask radially inward toward the silicon cylinder.
Printing a plurality of semiconductor devices on a sidewall of a silicon cylinder may comprise projecting light through a planar photomask toward the silicon cylinder and rotating the silicon cylinder to enable the light to sequentially strike different portions of the silicon cylinder.
Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale. The following detailed description of the disclosure will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown. In the drawings:
Certain terminology is used in the following description for convenience only and is not limiting. The words “lower,” “bottom,” “upper,” “top,” “left” and “right” and the like designate directions in the drawings to which reference is made. The words “inwardly,” “outwardly,” “upwardly” and “downwardly” and the like refer to directions toward and away from, respectively, the geometric center of the device, and designated parts thereof, in accordance with the present disclosure. Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element, but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import.
Embodiments of the invention are directed to cylindrical integrated circuits (ICs), devices and methods for making cylindrical integrated circuits, and electronic devices containing such cylindrical integrated circuits. Such cylindrical ICs comprise a plurality of semiconductor devices (primarily transistors) printed on the curved sidewall of a cylindrical silicon ingot (rather than on flat silicon wafers, as with conventional ICs).
Instead of printing the layers of photomask patterns on a flat planar wafer, embodiments of the invention print the circuits on the side of a semiconductor cylinder typically grown as an ingot from the melt, such as by using Czochralski crystal pullers or any other suitable method. The electronic components are fabricated on the sidewall of the ingot, using one or more of the methods described herein or any other suitable method. Once the fabrication is completed, the cylinder is sliced or sawed into thin cylindrical discs with the integrated circuits printed on the sides. The wiring can then be connected as needed with other cylindrical integrated circuits to form three dimensional networks. Since the top flat surface of the cylinder is comprised of single crystal silicon, active devices and circuits can be integrated with other discs. The cylindrical integrated circuits may also be packaged in conventional surface mount and dual inline packages to replace planar ICs.
Referring now to the figures,
Each cylindrical IC comprises a plurality of semiconductor devices (primarily, but not necessarily only, transistors and diodes) with corresponding conductive lead wires. In
While
In one exemplary embodiment, a cylindrical IC of embodiments of the invention may have a diameter of about 20 millimeters and a height of about 5 millimeters, and may comprise numerous semiconductor devices on its sidewall.
As illustrated in
In conventional silicon chip manufacturing, a planar silicon wafer is coated with a photoresist. The desired semiconductor patterns are produced on a planar photomask. Light is beamed at the photomask such that the pattern is projected onto the photoresist layer. This pattern hardens into an exact representation of the photomask when it is developed. Etching then removes selective areas of the pattern using a plasma that reacts to the material not covered by the hardened photoresist.
Embodiments of the invention print the semiconductors on the silicon cylinder sidewall using sequential semiconductor processing techniques similar to that of conventional silicon chip production. However, in preferred embodiments of the invention, the circuit patterns are printed on the sidewall of the silicon cylinder by a concentric optical photolithography camera. The light beams are radially impingent on the photoresist coated surface through a cylindrical concentric photomask. The concentric photomask may be constructed out of thin curved glass or quartz, or any other suitable material. This technique may be termed concentric photolithography. After exposure, the photoresist is conventionally developed to transfer the pattern on to the cylindrical surface. Direct writing electron beam lithography may also be deployed without the need for photomasks.
Referring now to
Advantageously, the concentric geometry allows reduction of the image in the radial focal plane. In other words, the circuit pattern produced on the silicon cylinder is smaller/finer than the pattern on the photomask. Due to current limits in the ability to produce smaller/finer photomasks, this advantage may enable the production of smaller/finer circuitry on the silicon cylinder than is currently able to be produced using conventional photolithography. Systems and methods of concentric photolithography of embodiments of the invention provide improved performance and reduced fabrication cost and less-stringent contamination requirements than conventional photolithography.
The one or more light sources that create the light 48 may comprise any suitable type, number, and arrangement of light sources. Generally, whatever light sources are used for conventional planar photolithography should also work for the concentric photolithography of embodiments of the present invention, except that concentric photolithography requires 360 degrees of light around the photomask (except in embodiments in which the cylinder is rotated, as in the alternative embodiments described below).
Traditionally, the light sources have been mercury gas discharge lamps that were used to extract single wavelengths of 436 nanometers (nm) (“g-line”), 405 nm (“h-line”), and 365 nm (“i-line”) for printing lines larger than 0.5 micrometers. Argon fluoride (ArF) 193 nm excimer laser sources have been used to bring the resolution down to 45 nm. Extreme UV (EUV) light (13.5 nm) sources are being used for state of the art 10 nm lithography. Again, these light sources that are used for conventional planar photolithography should also work for the concentric photolithography of embodiments of the present invention.
For cylindrical sidewall printing, one exemplary embodiment may use a ring of many (e.g., 50) Ultra-Violet Light Emitting Diodes (UV LEDs) concentric with the circular photomask. The LED ring diameter and the diode spacing would depend upon the light intensity, the depth of focus, and other factors. The diameter of the light source ring may be, for example, ten times the diameter of the silicon cylinder.
Rather than spacing a larger number of light sources around the photomask, alternative embodiments might use a smaller number of light sources with properly arranged mirrors to provide the desired 360 degrees of light (in this regard, the lights and mirrors together may be considered lights sources).
The cylindrical photomask may be constructed of any suitable curved and/or flexible glass, such as Corning™ Willow™ glass (which is desirably transparent in the g- h- and i-line wavelengths).
Systems and methods of concentric photolithography of embodiments of the invention may use ultra-violet radiation, extreme ultra-violet radiation (EUV), electron beams, x-rays, or any other form of radiation or particles.
Systems and methods of concentric photolithography of embodiments of the invention may use any suitable conventional techniques of semiconductor manufacturing, such as oxidation, diffusion, photolithography, etching, chemical vapor and physical deposition, planarization, ion implantation and metallization, etc., except that the circuit is printed on the sidewalls of a cylinder instead of on a planar wafer.
Cylindrical ICs of embodiments of the invention may be packaged in conventional dual in-line package (DIP) or surface-mount (SMT) packages so that the cylindrical ICs may be mounted on conventional PCBs to fabricate circuits connected with conventional planar ICs. Although it does not show the DIP package,
Cylindrical ICs of embodiments of the invention may be integrated with an antenna or sensors in the horizontal or vertical wiring planes to make radio frequency identification (RFID) transmission and detection systems with passive or active low cost memory tags. Such RFID tags can be fabricated using roll-to-roll technology at a low cost, allowing large volume implementation of inventory management systems, internet of things (IoT), or other big database generation applications.
In alternative embodiments of the invention, conventional photolithography techniques such as step-and-repeat refractive optics or scanning projection reflecting optics or other methods presently being used for planar wafer pattern printing can be used to print on the sidewalls of the rotating silicon cylinder.
In an alternative embodiment to print on the curved sides of a cylinder using a planar photomask,
Systems and methods of concentric photolithography of embodiments of the invention enable the complete fabrication process to be fully automated to operate on a continuous basis with minimal clean room contamination requirements, substantially reducing the fab clean room building size and volume and the associated construction and operating costs.
Cylindrical ICs of embodiments of the invention may be integrated in three dimensions with other devices or circuits using radial wiring schemes on laminate dielectric surfaces in perpendicular planes. Such three-dimensional integration of the cylindrical IC allows cooling of the electronics by efficient conduction, convention, and radiation heat transfer.
The cylindrical geometry would enable improved computer architecture by enabling effective logic and memory interface, faster systems, and effective telecommunication devices.
Neural network circuits may be fabricated utilizing the cylindrical ICs of embodiments of the invention with neural wiring and logic elements in the vertical plane radially emanating from one node to another to form neuromorphic systems.
Supercomputers designed with cylindrical ICs of embodiments of the invention would be capable of very high performance due to vertical logic and memory integration, efficient power distribution, and effective thermal management.
Light emitting diodes (LEDs) may be fabricated by epitaxially depositing thin p-type and n-type compound semiconductor thin films on the side walls of a lattice matched semiconductor as shown in
Microwave and ultrasonic piezoelectric sources and detectors may also be constructed in the cylindrical geometry shown in
Systems on a chip (SoC) may be fabricated with three-dimensionally integrated cylindrical ICs of embodiments of the invention with high speed performance and extensive power distribution and thermal management capabilities.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
This application claims priority to pending U.S. Provisional Application Ser. No. 62/777,122, filed Dec. 8, 2018, the contents of which are incorporated herein by reference in its entirety.
Number | Date | Country | |
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62777122 | Dec 2018 | US |