Patent Publication Number: US-2015069667-A1

Title: Nano-parts fabrication method

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method of fabricating small mechanical parts or particles. More particularly, it relates to manufacturing parts of nanometer scale through an optical thin-film depositing and coating technology. 
     BACKGROUND 
     With the continuing scaling in device making, small tiny mechanical parts are in high demand in order to be able to fit into tiny real estate space, whether it is for bio-medical applications such as artificial parts embedded inside human body to replace failed or non-functional human body parts or industrial applications such as micro parts fabrication, or miniature parts used in semiconductors, micro robots etc. For example, with MEMS (micro-electro-mechanical systems) switches starting to be used in, for example, television display and other electronic control systems, small mechanical parts and/or particles, whose size is often in the order of a few nanometers (nm) to a few micrometers (um) or sometimes from sub-nanometer to some tens of micrometers are often required to be manufactured in such a way that satisfies their specific application needs. 
     SUMMARY 
     This invention provides a new method of creating or making tiny mechanical parts through the vacuum coating and/or deposition technology. More specifically, embodiments of present invention provide a method of fabricating small mechanical parts or particles of nanometer scale known herein as nano-parts, through precision optical thin film deposition and/or coating technique. The precision optical thin film coating process may include, but not limited to, an EBD (Electron-Beam Deposition) process, an IAD (Ion-Assisted Deposition) process including PIAD (Plasma-Ion-Assisted Deposition) process, an IBS (Ion-Beam Sputtering) process, etc. The material deposited may include metal or metal-oxide, and the precision thin film deposition/coating process may be able to control the rate of deposition up to sub-nanometer to around a few nanometers range. Before deposition, standard lithographic patterning process commonly used in semiconductor industry may be applied to create one or more openings in a substrate corresponding to shapes of one or more nano-parts to be made. In other words, a mold may be created out of the substrate that takes the shapes of one or more nano-parts to be manufactured. The metal or metal-oxide material may then be applied to the substrate mold, layer-by-layer, through a deposition and/or coating process. After removing unwanted coating material in areas outside the openings of nano-parts shapes, the tiny mechanical parts of nano-meter range size may be separated from the substrate. 
     More specifically, embodiments of the present invention provide a method which includes having a first set of shapes defining a set of particles, the set of particles being less than one micrometer in size; creating a set of openings in a substrate, the set of openings having a second set of shapes that are complimentary to the first set of shapes of the set of particles; filling the set of openings with a material through a deposition process to form the set of particles; and separating the set of particles from the substrate. 
     In one embodiment, the method further includes applying a thin layer of non-adhesive material to a top surface of the set of openings before filling the set of openings with the material. In one instance, the thin layer of non-adhesive material is a thin layer of oleic acid being applied to the set of openings, through a spin-on process, and having a thickness of a single layer of molecules of the oleic acid. 
     In one embodiment, separating the set of particles from the substrate includes applying a supersonic vibration to the substrate, the vibration causing the set of particles to detach from a surface of the set of openings in the substrate. In one instance, applying the supersonic vibration to the substrate further includes immersing the substrate in a solution, the solution conveying the supersonic vibration to the substrate. 
     In another embodiment, separating the set of particles from the substrate further includes removing the material that are above a top surface level of the substrate by a chemical-mechanic-polishing process, the removing ensuring that the set of particles are not connected to each other by the material. 
     In yet another embodiment, filling the set of openings with the material includes applying a physical vapor deposition (PVD) process to deposit the material layer-by-layer on top of a surface of the set of openings in the substrate. 
     In a further embodiment, the set of particles has a size larger than 1 nm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description of embodiments of the invention, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a demonstrative illustration of top and cross-sectional views of a template manufactured for making nano-parts according to one embodiment of present invention; 
         FIG. 2  is a demonstrative illustration of a cross-sectional view of a step of a method of making nano-parts according to one embodiment of present invention; 
         FIG. 3  is a demonstrative illustration of a cross-sectional view of a step of a method of making nano-parts according to another embodiment of present invention; 
         FIG. 4  is a demonstrative illustration of a cross-sectional view of a step of a method of making nano-parts according to yet another embodiment of present invention; 
         FIG. 5  is a demonstrative illustration of a method of making nano-parts through an electron-beam deposition process according to one embodiment of present invention; 
         FIG. 6  is a demonstrative illustration of a method of making nano-parts through an ion-assisted deposition process according to another embodiment of present invention; and 
         FIG. 7  is a demonstrative illustration of a method of making nano-parts through an ion-beam sputtering deposition process according to yet another embodiment of present invention. 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments of present invention. However it will be understood by those of ordinary skill in the art that embodiments of present invention may be practiced without these specific details. In other instances, well-known details of structure and method of use or operation may not be described in detail in order not to obscure description of embodiments of the present invention. 
     Some portions of the detailed description in the following may be presented in terms of algorithms and/or symbolic representations of operations. These algorithmic descriptions and representations may be the techniques used by those skilled in the arts to convey the substance of their work to others skilled in the art. 
     In the following description, various figures, diagrams, flowcharts, models, and descriptions may be presented as different means to effectively convey the substances and illustrate different embodiments of the invention that are proposed in this application. It shall be understood by those skilled in the art that they are provided merely as exemplary and/or demonstrative samples, and shall not be constructed as limitation to the invention. 
       FIG. 1  is a demonstrative illustration of top and cross-sectional views of a template manufactured for making nano-parts according to one embodiment of present invention. More specifically, one embodiment of present invention may include determining or defining a set of small parts or particles, that may be nanometer-to-micrometer in size, and determining or defining their corresponding shapes. These small parts or particles may sometimes be referred to hereinafter as nano-parts as well. One embodiment of the method may further include preparing a template or a mold  100  which includes one or more shapes, such as shapes  111 ,  112 , and  113 , to name a few, and others as being demonstratively illustrated in  FIG. 1  that are formed in a substrate  101 . Shapes  111 ,  112 , and  113  are complementary shapes to those of the set of nano-parts and thus may equally be significantly small in size, in the order of a few nanometers (nm) or even sub-nanometer to hundreds of nanometers. For example, shapes  111 ,  112 , and  113  may have a size from 1 nm to 1000 nm (1 um). However, a person skilled in the art will appreciate that embodiments of present invention are not limited in this aspect and the size of these shapes may sometimes be up to a few micrometers (um) such as around 10 um. Shapes  111 ,  112 , and  113  in mold  100 , as being discussed above, are complementary shapes to these small mechanical parts or particles (nano-parts) to be manufactured. Corresponding to these nano-parts, shapes  111 ,  112 , and  113  may thus be referred to as nano-scale shapes. 
     Shapes  111 ,  112 , and  113  are three-dimensional in nature, to have their respective depths and lateral dimensions that may be collectively referred to herein as “sizes” and in particular a lateral dimension may be defined as size of the shape throughout this application. Shapes  111 ,  112 , and  113  may be formed for example through an etching process into substrate  101 . For example, as some non-limiting examples, one shape may have the shape of a “nut” and another may have the shape of a “washer”, similar to those that are often used in general mechanics as fastener. Substrate  101  may be a semiconductor substrate, a glass substrate, a ceramic substrate, a metal substrate, or any other substrate of suitable material and suitable for the manufacturing process as being described below in more details. 
     In one embodiment, shapes  111 ,  112 , and/or  113  may be formed inside substrate  101 , directly below a surface thereof, by applying a standard photolithographic patterning process as such patterning process is known in the art and well established in the semiconductor industry. In another embodiment, shapes  111 ,  112 , and/or  113  may be etched into the surface of substrate  101  through a laser blazing process. It is expected that sizes of these shapes may be affected and/or sometimes determined by the particular process and/or tools used in the creation thereof. Other currently existing or future developed processes, such as an electronic beam (e-beam) exposure process, are fully contemplated here, together with the various sizes of shapes that are offered or made available by these processes. 
       FIG. 2  is a demonstrative illustration of a cross-sectional view of a step of a method of making nano-parts according to one embodiment of present invention. More specifically, the method includes patterning a substrate  201  to have a plurality (including one) of openings  211 ,  212 ,  213 , and  214  having shapes representing a plurality of parts or particles of nano-meter scale. In other words, openings  211 ,  212 ,  213 , and  214  represent complimentary shapes of a plurality of nano-parts to be manufactured. According to one embodiment of present invention, after substrate  201  being patterned to have the plurality or set of openings  211 ,  212 ,  213 , and  214  on top thereof, thereby forming template or mold  200 , substrate  201  may subsequently be exposed to, or subjected to, a surface treatment process which cleans and keeps clean of the surface area of substrate  201  particularly the surface area of openings  211 ,  212 ,  213 , and  214 . 
     According to one embodiment, following the cleaning, a thin layer of non-adhesive material  202  such as, for example, a thin film or thin layer of oil such as an oleic acid may be applied to the clean surface of substrate  201  including top surface areas of openings  211 ,  212 ,  213 , and  214 . The oleic acid  202  may preferably be spread or applied, in a thickness of single layer of molecules, to openings  211 ,  212 ,  213 , and  214  in a spin-on process for example, thus lining openings  211 ,  212 ,  213 , and  214 . The thin oleic acid film  202  of single molecule layer thickness may help remove, detach, and/or separate from substrate  201  nano-parts that, as being described below in more details, may be formed inside opening shapes  211 ,  212 ,  213 , and  214  in later process steps. 
       FIG. 3  is a demonstrative illustration of a cross-sectional view of a step of a method of making nano-parts according to another embodiment of present invention. More specifically, the method includes forming a layer of suitable or desired material such as metal or non-metal materials through a deposition process  301  into nano-scale shapes  211 ,  212 ,  213 , and  214  to form their corresponding nano-parts  311 ,  312 ,  313 , and  314 . The deposition process  301  may include, for example, a physical vapor deposition (PVD) process or an ion-beam sputtering (IBS) process. The physical vapor deposition may further include, for example, an electronic-beam deposition (EBD) process, an ion-assisted deposition (IAD) process, or an plasma-ion-assisted deposition (PIAD) process, to name a few. Other thin-film deposition processes or coating processes may be used as well. 
     The above various deposition processes or techniques may be used to form nano-parts  311 ,  312 ,  313 , and  314  with proper metal or non-metal material (such as metal-oxide) being deposited or coated in a layer-by-layer process inside openings  211 ,  212 ,  213 , and  214  created in template  200 . Template  200  is the host of openings of nano-scale shapes  211 ,  212 ,  213 , and  214 . As being described above, nano-scale shapes  211 ,  212 ,  213 , and  214  correspond to and have complimentary shapes of nano-parts  311 ,  312 ,  313 , and  314  of under manufacturing. 
     Nano-parts  311 ,  312 ,  313 , and  314  may be deposited to have a height either below or above a top surface of substrate  201 . Coating material deposited directly above the top surface of substrate  201 , such as  310  in  FIG. 3 , may be partially connected to nano-parts  311 ,  312 ,  313 , and  314 . For example, in a conformal deposition process of making nano-parts  311 ,  312 ,  313 , and  314 , coating material  310  on the top surface of substrate  201  may be part of a conformal layer, and the conformal layer may include nano-parts  311 ,  312 ,  313 , and  313  as well as any material in-between the nano-parts and/or the coating material  310 . On the other hand, in a directional deposition process, in particular when thickness of the finally formed nano-parts  311 ,  312 ,  313 , and  314  is made to be less than the height of substrate  201 , having a thickness less than the depth of the openings, coating material  310  may be “isolated” on top of substrate  201  in areas other than any openings, and separated from or at least not substantially connected to the finally formed nano-parts  311 ,  312 ,  313 , and  314 . 
     With a regular PVD processing technology, a target material, such as metal or non-metal material that may purposely be selected based upon any specific requirement for forming nano-parts  311 - 314 , may first be determined. The target material is then heated up inside a vacuum chamber by an electrical resistor or through electron bombardment until the temperature of target material has reached to an evaporating or subliming point. Atoms and/or molecules may then escape from the target material and are deposited onto the surface, where openings  211 ,  212 ,  213 , and  214  are formed, of template  200 . During the PVD deposition process, specific conditions such as ambient temperature, pressure of chamber, and time duration may be varied and/or controlled to achieve adjustment in the rate of deposition. For example, the rate of deposition may be adjusted to be from about 0.1 nm per second (nm/s) to about 1.5 nm/s. Furthermore, with the help of a quartz crystal oscillate film thickness controller, thickness of deposited film may be controlled to within 10 nm to 10 um at an accuracy of less than a few nanometers. 
     Reference is briefly made to  FIG. 5 , which is a demonstrative illustration of a method of making nano-parts through an electron-beam deposition process according to one embodiment of present invention. More specifically, the electron-beam deposition (EBD) process may be performed inside a vacuum chamber. The chamber may contain a crucible  501 , with which an electron-beam generated from a hot filament is focused via a magnetic field onto a copper hearth that is filled with material to be evaporated, which may be a metal or other non-metal material such as a metal oxide. The electron beam heats the material, causing it to evaporate, radiate and condense on all surfaces inside the vacuum chamber that are in a direct line of sight  503  of crucible  501 . Furthermore, a rotating substrate holder  504  may be used to keep substrate  201 , which is wafer  510  in  FIG. 5 , in a horizontal plane and a shutter  502  may be used to stop the deposition and/or coating process when the desired film thickness has been achieved. The substrate  201  may be heated to a temperature of 150˜300 degree C. to help the nucleation of the material. 
       FIG. 6  is a demonstrative illustration of a method of making nano-parts through an ion-assisted deposition process according to another embodiment of present invention. More specifically, similar to the electron-beam deposition process as being illustrated in  FIG. 5 , ion-assisted deposition (IAD) process may be performed inside a chamber as well, and uses a crucible  601  to generate evaporant  603  of the material that are selected to be deposited. The IAD process further has a substrate holder  606  holding wafer  610 , which is substrate  201 , and uses a shutter  605  to control the amount of deposition. Different from the EBD process described above, the IAD process uses an ion source  602  to increase the activation energy of the deposited material, which results in a denser and more uniform film being formed on the surface of substrate  201 . More specifically, the IAD process uses an ion gun  602  to bombard the surface of substrate  201  ( 610 ) with a flux of high-energy ions  604  composed of oxygen and/or argon gas. The bombardment by this energetic beam is similar to atomic shot peering, which helps producing a denser film. 
       FIG. 7  is a demonstrative illustration of a method of making nano-parts through an ion-beam sputtering deposition process according to yet another embodiment of present invention. More specifically, the ion-beam sputtering (IBS) process may produce argon ion (Ar+) beam  702 , from an ion source  701 , by applying bias current of certain RF (radio frequency) to ion source  701 . The argon ion beam  702  so produced may subsequently be accelerated until it possesses an energy of as high as 1000 eV, which is then applied to bombard the surface of a target material  703 , which is the material selected for deposition to make nano-parts. Upon momentum transfer effect, atoms and/or molecules from target material  703  may leave surface of target material  703 , forming a secondary beam  704  traveling toward a wafer  710 , which in the current application is substrate  201  of template  200 . With substrate  201  ( 710 ) being placed on a wafer motor  705  which facilitate the positioning of substrate relative to secondary beam  704 , material from target  703  is then deposited onto opening shapes  211 ,  212 ,  213 , and  214 , as well as rest surface areas of substrate  201 , which is illustrated in  FIG. 3  as coating material  310 . 
     Within different deposition processes such as EBD, IAD and IBS as being described above, different thickness of deposited or coated film may be achieved, through a layer-by-layer deposition or coating approach, with different accuracy control. For example, with a regular PVD process including the EBD and/or the IAD process, film thickness may generally be controlled layer-by-layer to be within about 2 nm-3 nm. In the meantime, the IBS process may be able to achieve a film thickness accuracy of up to sub-nanometer, i.e. less than 1 nm. 
     Reference is now made back to  FIG. 4 , which is a demonstrative illustration of a cross-sectional view of a step of a method of making nano-parts according to yet another embodiment of present invention. More specifically, after deposition of appropriate material, metal or non-metal including metal-oxide, inside opening shapes  211 ,  212 ,  213 , and  214  which were made to be complementary shapes of nano-parts  311 ,  312 ,  313 , and  314 , nano-parts  311 ,  312 ,  313 , and  314  may be separated or detached from substrate  201 , or more precisely from a surface of the opening shapes  211 ,  212 ,  213 , and  214 . 
     Separating nano-parts  211 ,  212 ,  213 , and  214  from substrate  201  may be achieved by applying a supersonic cleaning process  401 . More specifically, substrate  201  together with nano-parts  211 ,  212 ,  213 , and  214  may be immersed or soaked in a solution while the solution is being subjected to a supersonic vibration process. The vibration may be conveyed via the solution to substrate  201 , thus causing nano-parts  311 - 314  to separate or detach from substrate  201  and become individual nano-parts  411 ,  412 ,  413 , and  414 . 
     According to another embodiment, coating material  310 , which may be deposited directly on the top surface of substrate  201  in areas away from areas of openings  211 ,  212 ,  213 , and  214 , may be first removed in order to facilitate the separation of nano-parts  311 ,  312 ,  313 , and  314  from substrate  201 . The removal of coating material  310  may be made through, for example, a chemical-mechanic-polishing (CMP) process. In particular, when coating material  310  is substantially connected to nano-parts  311 ,  312 ,  313  and  314 , which may be the case when formation of nano-parts  311 ,  312 ,  313 , and  314  was made through in a conformal deposition process, the removal of coating material  310  may ensure that nano-parts  311 ,  312 ,  313 , and  314  are separated from each other such that their separation from substrate  201  may be made with relative ease. The CMP process may remove the excessive coating material  310  as well as a top portion of material of nano-parts  311 ,  312 ,  313 , and  314  that are above a top surface level of substrate  201 . The CMP process thus ensures that nano-parts  311 ,  312 ,  313 , and  314  have a thickness that is defined by the depths of each individual openings  211 ,  212 ,  213 , and  214  created in substrate  201 , and are individually separated. This helps the subsequent process of separating nano-parts  311 ,  312 ,  313 , and  314  from substrate  201  through, for example, a supersonic vibration process  401  to become nano-parts  411 ,  412 ,  413 , and  414  as being illustrated in  FIG. 4 . 
     While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those of ordinary skill in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and changes as fall within the spirit of the invention.