Method for manufacturing semiconductor device

Abstract

Semiconductor devices and methods of manufacturing the same using carbon nanotubes are provided. In an embodiment, a nanotube stack is formed and then a non-destructive removal process is used to reduce the thickness of the nanotube stack. Devices such as transistors can then be formed from the reduced nanotube stack.

Description

Technical Field

[0001] Embodiments of the present application relate to methods of manufacturing semiconductor devices. Background Art

[0002] Semiconductor devices are used in a variety of electronic applications such as, for example, personal computers, cell phones, digital cameras, and other electronic devices. Semiconductor devices are typically manufactured by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductor material layers over a semiconductor substrate and patterning the various material layers using photolithography to form circuit components and elements thereon.

[0003] The semiconductor industry continues to increase the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continuously reducing the minimum feature size, allowing more components to be integrated into a specific area. As the feature size in the semiconductor manufacturing process continues to shrink, more challenges emerge that need to be addressed. Summary of the invention

[0004] Some embodiments of the present application provide a method for manufacturing a semiconductor device, the method comprising: forming a nanotube stack, wherein each nanotube is aligned with adjacent nanotubes; depositing a support layer over the nanotube stack; removing the support layer, wherein removing the support layer also removes at least one layer of nanotubes from the nanotube stack; and depositing a gate electrode over the remaining portion of the nanotube stack.

[0005] Other embodiments of the present application provide a method for manufacturing a semiconductor device, the method comprising: filtering a carbon nanotube solution through a filter membrane, the filter membrane having an electrostatic field, wherein during the filtering process, a first layer of carbon nanotubes, a second layer of carbon nanotubes, and a third layer of carbon nanotubes are deposited on the filter membrane; transferring the first layer of carbon nanotubes, the second layer of carbon nanotubes, and the third layer of carbon nanotubes to a dielectric layer above a substrate; removing the third layer of carbon nanotubes using a destructive removal process; removing the second layer of carbon nanotubes using a non-destructive removal process; and forming a gate electrode above the first layer of carbon nanotubes after removing the second layer of carbon nanotubes.

[0006] Still other embodiments of the present application provide a method for manufacturing a semiconductor device, the method comprising: receiving a solution containing carbon nanotubes; arranging the carbon nanotubes into an orderly arranged carbon nanotube stack using a first electrostatic field; placing the orderly arranged carbon nanotube stack on a dielectric material; thinning the orderly arranged carbon nanotube stack for a first time using a first process; thinning the orderly arranged carbon nanotube stack for a second time using a second process different from the first process; and after thinning the orderly arranged carbon nanotube stack for the second time, depositing source / drain contacts electrically connected to the orderly arranged carbon nanotube stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] When read in conjunction with the accompanying drawings, various aspects of the present invention can be best understood from the following detailed description. Note that, in accordance with standard practice in the industry, the various components are not drawn to scale. In fact, the size of the various components may be arbitrarily increased or decreased for clarity of discussion.

[0008] Figure 1A-1B Filtering a carbon nanotube solution is shown according to some embodiments.

[0009] Figure 2A-2B Placing a nanotube stack on a substrate is shown according to some embodiments.

[0010] Figure 3A-3B A first thinning of a nanotube stack is shown according to some embodiments.

[0011] Figure 4A-4B Depositing a support layer according to some embodiments is shown.

[0012] Figure 5A-Figure 5B A second thinning of the nanotube stack is shown according to some embodiments.

[0013] Figure 6A-6B Removal of spacers from around nanotubes is shown in accordance with some embodiments.

[0014] Figure 7A-7D The formation of a transistor according to some embodiments is shown. DETAILED DESCRIPTION

[0015] The following disclosure provides many different embodiments or examples for implementing different features of the present invention. Specific examples of components and arrangements are described below to simplify the present invention. Of course, these are merely examples and are not intended to limit the present invention. For example, in the following description, forming a first component above or on a second component may include an embodiment in which the first component and the second component are directly contacted, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not be in direct contact. In addition, the present invention may repeat reference numerals and / or characters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0016] Furthermore, for ease of description, spatially relative terms such as "below," "beneath," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or component to another (or additional) elements or components as shown in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should likewise be interpreted accordingly.

[0017] Embodiments will now be described with respect to specific embodiments utilizing a vacuum system and filters to deposit and align a stack of carbon nanotubes. Once the stack of carbon nanotubes is formed, a controlled reduction process may be utilized to produce one or more layers of carbon nanotubes, which are then used to form semiconductor devices. However, the embodiments presented herein are intended to be illustrative of the invention, rather than limiting, as these concepts may be used in various embodiments, such as various front-end-of-line (FEOL) processes and back-end-of-line (BEOL) processes.

[0018] Reference now Figure 1A-1B , showing the deposition and alignment of carbon nanotubes 101 (in Figure 1A It is not visible in the Figure 1B100) is a system 100 (shown and described in FIG. 100). In an embodiment, the system 100 includes a vacuum chamber 103 connected to the filter 105 by a connecting tube 107. In an embodiment, the vacuum chamber 103 can be a chamber having a first inlet 109 and a first outlet 111. In an embodiment, the size and shape of the vacuum chamber 103 can be set to enhance the ability of the vacuum chamber 103 to help the carbon nanotubes 101 to be deposited and arranged in the system 100. In some embodiments, although the vacuum chamber 103 can be shaped as a conical flask, any suitable shape such as a cylindrical, hollow square tube, octagonal, etc. can be used. In addition, the vacuum chamber 103 can be surrounded by a shell 113, which is made of a material that is inert to various processing materials. In this way, although the shell 113 can be any suitable material that can withstand the chemicals and pressures involved in the filtering process, in an embodiment, the shell 113 can be glass, steel, stainless steel, nickel, aluminum, alloys thereof, combinations thereof, etc. However, any suitable material can be used for the shell 113 of the vacuum chamber 103.

[0019] A vacuum pump 115 may be connected to the first outlet 111. In an embodiment, the vacuum pump 115 is used to help create a desired vacuum within the vacuum chamber 103, and this pressure differential may then be used to help filter the carbon nanotubes 101 from the solution and deposit the carbon nanotubes 101 onto the filter 105 by reducing and controlling the pressure within the vacuum chamber 103. However, any suitable method of reducing the pressure in the vacuum chamber 103 may be used.

[0020] The connecting tube 107 extends through the gasket and into the first inlet 109 of the vacuum chamber 103 and connects the vacuum chamber 103 to the filter 105. In an embodiment, the connecting tube 107 is used to connect the vacuum chamber 103 to the filter 105 so that a pressure differential is applied between the vacuum chamber 103 and one side of the filter 105. In an embodiment, the connecting tube 107 can be any suitable material that can withstand the pressures and chemicals involved, and in some embodiments, can be a material such as glass, steel, stainless steel, nickel, aluminum, alloys of these, combinations of these, etc. However, any suitable material can be used.

[0021] Referring now to filter 105, Figure 1A An external view of the filter 105 and the location of the filter 105 within the system 100 are shown, and Figure 1B An internal view of the filter 105 is shown. Figure 1B As shown, in some embodiments, the filter 105 includes a filter membrane 117 (in Figure 1A It is not visible in Figure 1B), when the carbon nanotube solution 123 is pulled through the filter membrane 117 by the pressure difference from the vacuum chamber 103, the filter membrane 117 is used to filter the carbon nanotubes 101 from the carbon nanotube solution 123. In an embodiment, the filter membrane 117 can be a material such as polycarbonate, polytetrafluoroethylene or polyvinylidene fluoride, and its pore size is smaller than the carbon nanotubes 101 (so as to filter the carbon nanotubes 101), such as between about 0.01 μm and about 10 μm. However, any suitable material and any suitable pore size can be used.

[0022] Furthermore, although the above pore sizes are sufficient to simply remove the carbon nanotubes 101 from the carbon nanotube solution 123, using a simple filter by itself may not be sufficient to align the carbon nanotubes 101 during the filtration process. Thus, in some embodiments, the filter membrane 117 is also used to generate an electrostatic field (at Figure 1B When the carbon nanotubes 101 enter the electrostatic field 119 during the filtering process, the electrostatic field can be used to align the carbon nanotubes 101. In some embodiments, the electrostatic field 119 can be passively generated, while in other embodiments, the electrostatic field 119 can be actively generated during the filtering process.

[0023] Looking first at embodiments in which the electrostatic field 119 is passively generated, the filter membrane 117 may be used to generate a passive electrostatic field by coating the membrane with a coating material (for clarity, Figure 1B The filter membrane 117 is coated with a coating material (not shown separately) to generate an electrostatic field 119, and the coating material passively generates the required electrostatic field 119. In an embodiment, the coating material may include a hydrophilic material such as polyvinyl pyrrolidone (PVP), hexamethyldisilazane (HMDS), aluminum oxide (Al2O3), or a combination thereof. However, any suitable material may be used.

[0024] In embodiments where poly(vinyl pyrrolidone) is used as the coating material, the poly(vinyl pyrrolidone) passively generates the desired electrostatic field 119. In such embodiments, the electrostatic field 119 may have a voltage between about 0 V and about 10 V at a distance between about 0 nm and about 10 nm. However, any suitable electrostatic field 119 may be generated using passive generation, and all such methods of generating an electrostatic field may be utilized.

[0025] In another embodiment, the electrostatic field 119 can be actively generated by capturing negative charges before or during the filtration process. In such an embodiment, rather than permanently coating the filter membrane 117 with a single material, the filter membrane 117 is actively charged with a surfactant before the filtration process. For example, in some embodiments, the surfactant can be a negatively charged material such as sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), sodium deoxycholate (DOC), or a combination thereof. However, any suitable surfactant can be used.

[0026] In an embodiment, the surfactant may be introduced into the filter membrane 117 prior to the introduction of the carbon nanotube solution 123. In an embodiment, the surfactant may be introduced into the filter membrane 117 by flowing the surfactant over and / or through the filter membrane 117 such that at least a portion of the negative charge from the surfactant is captured by the filter membrane 117 and at least partially retained in place during a subsequent filtration process.

[0027] In another embodiment, the surfactant may be included as part of the carbon nanotube solution 123. In such an embodiment, the surfactant may be included in the carbon nanotube solution 123, rather than flowing the surfactant over the filter membrane 117 prior to introducing the carbon nanotube solution 123. In other embodiments, the surfactant may flow through the filter membrane 117 prior to the filtration process and also be reintroduced into the carbon nanotube solution 123. Any suitable combination of processes for introducing the surfactant into the filter membrane 117 may be utilized, and all such processes are fully intended to be included within the scope of the embodiments.

[0028] In embodiments where a surfactant is used to generate an electrostatic field 119 in an active generation process, the surfactant actively generates the desired electrostatic field 119 in each filtration process. In such embodiments, the electrostatic field 119 may have a voltage between about 0 V and about 10 V at a distance between about 0 nm and about 10 nm. However, any suitable electrostatic field 119 may be generated using active generation, and all such methods of generating an electrostatic field may be utilized.

[0029] Now back to Figure 1A , Figure 1A Also shown is a solution container 121 connected to the side of the filter 105 opposite the vacuum chamber 103. In an embodiment, the solution container 121 can be used to store and / or supply the carbon nanotube solution 123 to the filter 105 (see Figure 1B). In this embodiment, the solution container 121 can be a container made of a material that can withstand the pressure and chemicals involved in the filtration process, and in some embodiments, can be a material such as glass, steel, stainless steel, nickel, aluminum, alloys thereof, combinations thereof, etc. However, any suitable material can be used.

[0030] In another embodiment, solution container 121 may be an inlet for carbon nanotube solution 123 to enter filter 105, and carbon nanotube solution 123 may be stored independently of filter 105 and / or even produced independently of filter 105. For example, in some embodiments, carbon nanotube solution 123 may be mixed and / or stored before being introduced into filter 105, and solution container 121 is not an independent system that is attached to and removed from system 100, but is a supply system that provides a steady supply of carbon nanotube solution 123 during the filtering process.

[0031] The carbon nanotube solution 123 includes carbon nanotubes 101 dispersed in a solvent 125. In embodiments, the carbon nanotubes 101 may be single-walled carbon nanotubes formed using any suitable method, such as a carbon arc discharge method (with subsequent purification), a laser evaporation method, catalytic chemical vapor deposition, ball milling and subsequent annealing, diffusion flame synthesis, electrolysis, polymer heat treatment, low temperature solid pyrolysis, combinations of these, etc. However, any suitable method of making the carbon nanotubes 101 may be used, and all such methods are fully intended to be included within the scope of the embodiments.

[0032] Optionally, in some embodiments, the carbon nanotubes 101 may be surrounded by spacers 129, which may serve a dual purpose of acting as a purifier for the carbon nanotubes 101 and helping to disperse the carbon nanotubes 101 in the carbon nanotube solution 123. Furthermore, by controlling the thickness of the spacers 129 around each carbon nanotube 101, the spacing of the carbon nanotubes 101 may also be controlled once the carbon nanotubes 101 are arranged adjacent to each other.

[0033] In an embodiment, the spacer 129 can be a material that can be placed and removed from the carbon nanotubes as needed without harmfully interfering with the manufacturing process between placement and removal. For example, in certain embodiments, the spacer 129 can be a material such as a surfactant (e.g., sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium deoxycholate, etc.), a polymer (e.g., poly[(9,9-dioctylfluorenyl-2,7-diyl)-alanine aminotransferase-co-(6,6'-{2,2'-bipyridine})

[0034] (poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,6'-{2,2'-bipyridine})), isoindigo-based poly(9,9-dioctylfluorene), poly[9-(1-octyloyl)-9H-carbazole-2,7-diyl], etc.), dielectric materials (e.g., HfO2 / SiO2 / Al2O, etc.) or even other nanotubes (e.g., boron nitride nanotubes, molybdenum disulfide nanotubes, etc.). However, during the filtering process, any suitable material or combination of materials can be used to surround and coat the carbon nanotubes 101.

[0035] Any suitable process may be used to place the spacers 129 around the carbon nanotubes 101. For example, the spacers 129 may be placed around each carbon nanotube 101 using processes such as chemical vapor deposition, atomic layer deposition, surfactant coating, polymer coating, combinations of these, and the like. Furthermore, in an embodiment, once the carbon nanotubes 101 have been deposited adjacent to each other, the spacers 129 are used to control the spacing between adjacent carbon nanotubes 101. The spacers 129 may have a thickness ranging from about 100 mm to about 100 mm. However, any suitable placement method and any suitable thickness may be used.

[0036] In an embodiment, the carbon nanotube solution 123 is formed by placing the carbon nanotubes 101 (with or without the spacers 129) in a solvent 125. In an embodiment, the solvent 125 can be used to contain the carbon nanotubes 101 during the transport process, and also to provide a suitable medium for the carbon nanotubes 101 to precipitate in a desired ordered orientation (further described below) during the filtration process. In some embodiments, the solvent 125 can be a solvent such as water (H2O), toluene, trichloroethane, tetrahydrofuran, or chloroform. However, any suitable material can be used as the solvent 125.

[0037] In an embodiment, the concentration of carbon nanotubes 101 in solvent 125 can be high enough to allow effective sedimentation of carbon nanotubes 101, while not being so high that the amount of carbon nanotubes 101 interferes with the sedimentation process. Thus, the concentration of carbon nanotubes 101 in carbon nanotube solution 123 can be between about 0.001 mg / mL and about 1 mg / mL. However, any suitable concentration can be used.

[0038] In addition, although the carbon nanotube solution 123 is described as including the solvent 125 and the carbon nanotubes 101, this description is intended to illustrate the present invention rather than to limit the present invention. Specifically, the carbon nanotube solution 123 may include any other suitable or desired additives, such as a surfactant for actively generating the desired electrostatic field 119. All of these additives are fully included within the scope of the embodiments.

[0039] To start the filtering process, the carbon nanotube solution 123 is placed in the solution container 121, and the solution container 121 is connected to the filter 105 so that the carbon nanotube solution 123 can flow to the filter membrane 117. In addition, a vacuum is generated in the vacuum chamber 103 using the vacuum pump 115 as a driving force to pull the carbon nanotube solution 123 through the filter membrane 117. In an embodiment, the vacuum pump 115 connected to the first outlet 111 can be used to reduce the pressure in the vacuum chamber 103 to between about 1 mtorr and about 760 torr. However, any suitable pressure can be used.

[0040] With the vacuum in the vacuum chamber 103 in place, a pressure differential is created between a first side of the filter membrane 117 facing the vacuum chamber 103 and a second side of the filter membrane 117 facing the carbon nanotube solution 123. With the pressure differential applied, the carbon nanotube solution 123 is pulled through the filter membrane 117, and the carbon nanotubes 101 are filtered out of the solvent 125 as the solvent 125 passes through the filter membrane 117, while the filter membrane 117 captures the carbon nanotubes 101 that are too large to pass through the filter membrane 117.

[0041] In addition, due to the presence of an electrostatic field 119 (passively or actively generated) on the filter membrane 117, when the carbon nanotubes 101 are deposited on the filter membrane 117, the combination of the electrostatic field 119 and the van der Waals force also aligns the carbon nanotubes 101, so that the carbon nanotubes 101 are parallel and aligned with each other. In particular, in an embodiment where the carbon nanotubes 101 have a negative charge (e.g., from a negatively charged surfactant wrapped around the carbon nanotubes 101 as a spacer 129) and the electrostatic field 119 also has a negative charge, when the carbon nanotubes 101 are filtered by the filter membrane 117, the electrostatic field 119 will work to force the carbon nanotubes 101 to align parallel to each other.

[0042] As the filtering process continues, the carbon nanotubes 101 in the carbon nanotube solution 123 are deposited as a first layer 131 of carbon nanotubes 101, wherein the carbon nanotubes 101 are arranged adjacent to each other in the first layer 131. Furthermore, once the first layer 131 of the carbon nanotubes 101 is deposited, a second layer 201 of the carbon nanotubes 101, a third layer 203 of the carbon nanotubes 101, a fourth layer 205 of the carbon nanotubes 101, a fifth layer 207 of the carbon nanotubes 101, and a sixth layer 209 of the carbon nanotubes 101 are deposited to form a stack 211 of carbon nanotubes 101 (not shown). Figure 1B , but hereinafter referred to as Figure 2A During the filtration process, any suitable number of layers of carbon nanotubes 101 may be deposited.

[0043] Figure 2A-2B Shown, Figure 2AShows Figure 2B , once the stack 211 of carbon nanotubes 101 has been deposited on the filter membrane 117, the stack 211 of carbon nanotubes 101 can be transferred to the first dielectric layer 215 located above the first substrate 217. In an embodiment, the first substrate 217 can be a support material such as a silicon material (e.g., a silicon wafer), a germanium material, a silicon germanium material, a gallium arsenide material, although it can be other substrates such as a semiconductor on an insulator (SOI), a strained SOI, a silicon germanium on an insulator, a glass substrate, a combination of these, etc. However, any suitable material can be used for the first substrate 217.

[0044] The first dielectric layer 215 is located above the first substrate 217 and is used to isolate devices subsequently formed on the first substrate 217. In an embodiment, the first dielectric layer 215 is a dielectric material such as silicon oxide, aluminum oxide, a combination of these, etc., which is deposited on the first substrate 217 using a deposition process such as chemical vapor deposition, sputtering, atomic layer deposition, a combination of these, etc. However, any suitable material and any suitable deposition process may be used.

[0045] In addition, despite Figure 2A The first dielectric layer 215 is shown directly on and in physical contact with the first substrate 217, but this is illustrative of the present invention and not limiting of the present invention. Rather, other dielectric materials and other substrate materials (e.g., silicon, germanium, gallium arsenide, combinations thereof, etc.) may also be present between the first dielectric layer 215 and the first substrate 217. Combinations of all of these layers may be used, and all of these are fully intended to be included within the scope of the embodiments.

[0046] Once the first dielectric layer 215 is positioned over the first substrate 217, the stack 211 of carbon nanotubes 101 is transferred from the filter membrane 117 to the first dielectric layer 215. In an embodiment, the transfer may be performed by first removing the filter membrane 117 from the system 100 and then applying a transfer layer (not separately shown) to the stack 211 of carbon nanotubes 101. In an embodiment, the transfer layer may be a material that may be used to hold and protect the stack 211 of carbon nanotubes 101 while also being used to allow for easy removal of the transfer layer once the stack 211 of carbon nanotubes 101 has been transferred. For example, the transfer layer may be polycarbonate (PC), polymethyl methacrylate (PMMA), and may be used interchangeably, although it may be any other suitable material such as methacrylate or phenolic resin.

[0047] In embodiments where the transfer layer is PMMA, a spin coating process, for example, may be used, although any other suitable deposition process may be used to place the transfer layer on the stack 211 of carbon nanotubes 101. Once in place, the PMMA may harden and cure. This cured PMMA both protects the stack 211 of carbon nanotubes 191 and allows the stack 211 of carbon nanotubes 191 to be moved and controlled by the transfer layer.

[0048] Once the transfer layer has been placed over the stack 211 of carbon nanotubes 101, the transfer layer can be used to place the stack 211 of carbon nanotubes 101 over the first substrate 217 and in contact with the first dielectric layer 215. The placement of the stack 211 of carbon nanotubes 101 can be performed by controlling the transfer layer (with the stack 211 of carbon nanotubes 101 attached thereto) and using the transfer layer to place the stack 211 of carbon nanotubes 101.

[0049] Additionally, in some embodiments, the stack 211 of carbon nanotubes 101 has a greater alignment along one surface of the stack 211 than along another surface of the stack 211. In such embodiments, the stack 211 of carbon nanotubes 101 may be positioned so that the surface having the greater alignment faces toward or is in physical contact with the first substrate 217. However, any suitable position may be utilized.

[0050] Once the stack 211 of carbon nanotubes 101 is placed on the first dielectric layer 215, the transfer layer can be removed. In an embodiment, the transfer layer can be removed using a stripping or etching process to remove the material of the transfer layer from the stack 211 of carbon nanotubes 101. Thus, while the material used to remove the transfer layer can depend at least in part on the material selected for the transfer layer, in an embodiment where the transfer layer is PMMA, the transfer layer can be removed by applying acetone to the PMMA, which dissolves poly-PMMA.

[0051] However, as one of ordinary skill in the art will appreciate, the use of PMMA for the transfer layer and the use of the transfer layer in general are not intended to limit the embodiments. Rather, any suitable method of transferring the stack 211 of carbon nanotubes 101 and integrating the stack 211 of carbon nanotubes 101 into the manufacturing process flow may be used. Any other suitable method for transferring the stack 211 of carbon nanotubes 101 is fully within the scope of the embodiments.

[0052] Once the stack 211 of carbon nanotubes 101 has been transferred, the stack 211 of carbon nanotubes 101 can have about 30 layers of carbon nanotubes 101 and about 60 layers of carbon nanotubes. Thus, the stack 211 of carbon nanotubes 101 can have a thickness between about 50 nm and about 100 nm. However, any suitable number of carbon nanotubes 101 and any suitable thickness can be used.

[0053] In addition, by using the solution-based filtration method described above, a high-density, extremely pure layer of carbon nanotubes 101 can be obtained. For example, the carbon nanotubes can have a purity greater than about 99.99%. In addition, in each layer of carbon nanotubes 101, the density is about 500 carbon nanotubes / micrometer. However, any suitable purity and any suitable density can be used.

[0054] Figure 3A-3B Shown, Figure 3A Shows Figure 3B Through the cross-sectional view of the top view of the line AA', once the stack 211 of carbon nanotubes 101 has been transferred to the first dielectric layer 215, the thickness of the stack 211 of carbon nanotubes 101 can be reduced. In an embodiment, a destructive thinning process (in Figure 3A In some embodiments, the destructive thinning process 301 may be performed using processes such as reactive ion dry etching, ultrasonic thinning, dissolution thinning, chemical embedding thinning, mechanical grinding, chemical mechanical polishing, chemical polishing, combinations thereof, etc. However, any suitable thinning process may be utilized.

[0055] In an embodiment, the stack 211 of carbon nanotubes 101 can be thinned so that only a desired number of carbon nanotubes (e.g., the first layer 131 of carbon nanotubes 101 and the second layer 201 of carbon nanotubes 101) remain within the reduced stack 303 of carbon nanotubes 101. In an embodiment, the reduced stack 303 of carbon nanotubes 101 can have about 3 layers of carbon nanotubes 101 and about 6 layers of carbon nanotubes. Thus, the reduced stack 303 of carbon nanotubes 101 can have a thickness between about 5 nm and about 10 nm. However, any suitable number of carbon nanotubes 101 and any suitable thickness can be used.

[0056] However, the destructive thinning process 301 as described above is not perfect. Thus, although many of the carbon nanotubes 101 to be removed are actually removed, the use of the destructive thinning process 301 will also damage and may not remove at least some of the carbon nanotubes 101 that are already present in the layer to be removed (e.g., the third layer 203 of the carbon nanotubes 101, the fourth layer 205 of the carbon nanotubes 101, the fifth layer 207 of the carbon nanotubes 101, and the sixth layer 209 of the carbon nanotubes 101), thereby forming damaged carbon nanotubes 305.

[0057] Figure 4A-4B Shown, Figure 4A Shows Figure 4B Through the cross-sectional view from the top of line AA', once the stack 211 of carbon nanotubes 101 has been reduced to the reduced stack 303 of carbon nanotubes 101, the support layer 401 is deposited on the reduced stack 303 of carbon nanotubes 101. In an embodiment, the support layer 401 serves as an adhesive layer for subsequent non-destructive thinning processes (not shown). Figure 4A-4B shown in, but referred to below Figure 5A-Figure 5B 401 ). Thus, in some embodiments, the material of the support layer 401 may be a metal such as nickel, molybdenum, tungsten, platinum, bismuth, combinations of these, etc. In such embodiments, the material of the support layer 401 may be deposited using an evaporation deposition process, a chemical vapor deposition process, a sputtering process, an atomic layer deposition process, combinations of these, etc. Any suitable deposition process may be utilized.

[0058] In other embodiments, the support layer 401 may be an organic material such as polymethyl methacrylate (PMMA), polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), polypropylene carbonate (PPC), other polycyclic aromatic hydrocarbons (PAH), phenyltrimethoxysilane (PTMS), polydimethylsiloxane (PDMS), rosin, combinations thereof, etc. In such embodiments, the material of the support layer 401 may be deposited using a deposition method such as spin coating, etc. However, any suitable material and deposition method may be used.

[0059] Figure 5A-Figure 5B Shown, Figure 5A Shows Figure 5B In the cross-sectional view from above through line AA', once the support layer 401 is deposited, additional carbon nanotubes 101 (e.g., the second layer 201 of carbon nanotubes) are removed from the reduced stack 303 of carbon nanotubes 101 to form the operating layer 503. In an embodiment, a non-destructive thinning process (in Figure 5A An additional layer of carbon nanotubes 101 is removed (indicated by the arrow labeled 501 in FIG. 5 ).

[0060] In some embodiments, the non-destructive thinning process 501 can be performed by removing the support layer 401 using a process such as mechanical peeling. In certain embodiments using mechanical peeling, an adhesive material such as scotch tape can be applied to the support layer 401. Once applied and adhered to the support layer 401, a force can be applied to the adhesive material to remove the support layer 401.

[0061] However, in addition to simply removing the support layer 401 itself, the removal of the support layer 401 will also remove the damaged carbon nanotubes 305 and one or more layers of carbon nanotubes 101 (e.g., Figure 5A In this way, the non-destructive thinning process 501 can be used to remove damaged carbon nanotubes 305 so that the damaged carbon nanotubes 305 do not interfere with subsequent processes. In addition, the non-destructive thinning process 501 can also be used to further thin the reduced stack 303 of carbon nanotubes 101 without generating additional damaged carbon nanotubes 101.

[0062] Furthermore, although the mechanical stripping process described above is a process that can be used to remove the support layer 401 and reduce the thickness of the stack 303, this description is intended to be illustrative rather than limiting. Specifically, any suitable non-destructive thinning process may also be used, such as thinning by carbon diffusion using a sacrificial metal layer during annealing, removing the spacers 129 inserted into the structured carbon nanotube film (e.g., stack 211) using chemical methods or vacuum annealing, or thinning the stack 303 by ultrasonic treatment or mechanical release. Any such non-destructive thinning method may be used, and all such methods are fully intended to be included within the scope of the embodiments.

[0063] Once the operating layer 503 of carbon nanotubes 101 has been formed, the operating layer 503 of carbon nanotubes 101 can have a single layer of carbon nanotubes 101. Thus, the operating layer 503 of carbon nanotubes 101 can have a thickness between about 1 nm and about 1.5 nm. However, any suitable number of carbon nanotubes 101 and any suitable thickness can be used.

[0064] exist Figure 3A-Figure 5B In the illustrated embodiment, a destructive thinning process 301 may be performed to reduce the stack 211 of carbon nanotubes 101 to only two layers of carbon nanotubes 101, while a non-destructive thinning process 501 removes only a single layer of carbon nanotubes 101, leaving a single layer of carbon nanotubes. However, this is illustrative and not limiting of the embodiment. Specifically, any suitable combination or repetition of steps may be utilized to obtain an operating layer 503 of carbon nanotubes 101.

[0065] For example, in some embodiments, the destructive thinning process 301 may be omitted entirely, or performed to remove only a minimal number of carbon nanotube 101 layers (e.g., to remove one or two layers of carbon nanotubes 101). In such embodiments, most or all of the thinning to obtain the operational layer 503 of carbon nanotubes 101 is performed using the non-destructive thinning process 501. Additionally, if such a non-destructive thinning process 501 is insufficient to thin the stack 211 of carbon nanotubes 101, the non-destructive thinning process 501 may be repeated one or more times to remove successive layers of carbon nanotubes 101 until the desired number of carbon nanotube 101 layers have been obtained. Any suitable number of iterations in any order may be used, and all such combinations are fully intended to be included within the scope of the embodiments.

[0066] Figure 6A-6B Shown, Fig. 6A Shows Figure 6B In the cross-sectional view from above through line AA', once the operational layer 503 of the carbon nanotubes 101 has been formed, the spacers 129 can optionally be removed from around the carbon nanotubes 101. In embodiments where the spacers 129 are surfactants or polymers, the spacers 129 can be removed using an annealing process, whereby the temperature of the material of the spacers 129 is raised until the material evaporates (if possible) or undergoes thermal decomposition, whereupon the material can be easily removed.

[0067] In another embodiment where the material of the spacers 129 is a dielectric material, the spacers 129 can be removed using an etching process. In a particular embodiment, the spacers 129 can be removed using a wet etching process where the etchant is selective to the material of the spacers 129. However, any suitable etching or other removal process can be utilized.

[0068] By utilizing spacers 129 during alignment and then removing the spacers 129, the spacing of the remaining carbon nanotubes 101 can be precisely controlled by controlling the thickness of the spacers 129. Thus, in some embodiments, the carbon nanotubes 101 can have a spacing between about 0 nm and about 100 nm. However, any suitable spacing can be used.

[0069] Figure 7A-7B A stereogram is shown (in Fig. 7A in the middle) and top view (in Figure 7B ), wherein the operation layer 503 of the carbon nanotubes 101 is used to form a planar transistor 700. In addition, Figure 7C A first cross-sectional view of the planar transistor 700 is shown by line CC′, Fig.7DA second cross-sectional view of planar transistor 700 is shown through line D-D'. In particular, once operating layer 503 of carbon nanotubes 101 is formed, source / drain contacts 707 can be formed, gate spacers 705 can be formed, gate dielectric 701 can be formed, and gate electrode 703 can be formed. However, any suitable combination of structures can be utilized.

[0070] In an embodiment, source / drain contacts 707 may be formed on opposite sides of a channel region within carbon nanotube 101 and contact sidewalls of source / drain regions within carbon nanotube 101 also located on opposite sides of the channel region. According to some embodiments, the formation of source / drain contacts 707 includes forming and patterning an etching mask such as a photoresist (on a Figure 7A-7D The etching mask is not shown separately in the figure, so that the area where the source / drain contact 707 is to be formed is exposed, while the other area is covered by the etching mask. Then a conductive layer such as a metal layer (e.g., tungsten, cobalt, a combination thereof, etc.) is deposited as a capping layer. Then a stripping process is performed to strip the etching mask and also remove the conductive layer portion on the etching mask. In this way, Figure 7A-7D As shown, source / drain contacts 707 remain.

[0071] Once the source / drain contacts 707 are formed, a gate spacer 705 may be formed to separate the source / drain contacts 707 from the gate electrode 703. In an embodiment, the gate spacer 705 may be formed by conformally depositing an insulating material and then anisotropically etching the insulating material. The insulating material of the gate spacer 705 may be silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, combinations thereof, and the like. However, any suitable material and deposition process may be used.

[0072] Once the material of the gate spacer 705 is formed, the gate dielectric 701 can be formed. In an embodiment, the gate dielectric 701 includes one or more dielectric layers such as one or more layers of silicon oxide, silicon nitride, metal oxide, metal silicate, etc. For example, in some embodiments, the gate dielectric 701 includes a high-k dielectric material such as a metal oxide or silicate of hafnium, aluminum, zirconium, lanthanum, manganese, barium, titanium, lead, and combinations thereof. The gate dielectric 701 may include a dielectric layer having a k value greater than about 7.0. The method of forming the gate dielectric 701 may include depositing the gate dielectric layer ( Figure 7A-7D However, the material of the gate dielectric 701 may be deposited using any suitable material and manufacturing method.

[0073] Once the material of the gate dielectric 701 is deposited, the material of the gate electrode 703 is deposited. The material of the gate electrode 703 may be formed by initially forming a gate electrode layer ( Figure 7A-7D ). In an embodiment, the gate electrode layer includes a conductive material and may be selected from a group including polycrystalline silicon (poly-Si), polycrystalline silicon germanium (poly-SiGe), metal nitrides, metal silicides, metal oxides, and metals. Examples of metal nitrides include tungsten nitride, molybdenum nitride, titanium nitride, and tantalum nitride, or a combination thereof. Examples of metal silicides include tungsten silicide, titanium silicide, cobalt silicide, nickel silicide, platinum silicide, erbium silicide, or a combination thereof. Examples of metal oxides include ruthenium oxide, indium tin oxide, or a combination thereof. Examples of metals include tantalum, tungsten, titanium, aluminum, copper, molybdenum, nickel, platinum, and the like.

[0074] In an embodiment, the gate electrode layer can be deposited by chemical vapor deposition (CVD), sputtering deposition, or other techniques known in the art and used to deposit conductive materials. The thickness of the gate electrode layer can be in the range of about 200 angstroms to about 4000 angstroms. The top surface of the gate electrode layer generally has an uneven top surface and can be flattened before patterning or gate etching of the gate electrode layer. At this point, dopants may or may not be introduced into the gate electrode layer. Dopants may be introduced by charge transfer, for example, by molecular doping techniques.

[0075] Once the gate electrode layer is formed, the gate electrode layer, the gate dielectric layer, and the gate spacers 705 may be planarized. In an embodiment, the material of the gate electrode layer and the material of the gate dielectric layer are planarized using, for example, a chemical mechanical polishing process to form the gate electrode 703 and the gate dielectric 701. However, any suitable planarization method may be used.

[0076] Once planarized, if desired, the source / drain contacts 707 can be exposed from any remaining capping material (e.g., the material of the gate spacers 705). In some embodiments, the source / drain contacts 707 can be exposed using, for example, a photolithographic mask and etching process, whereby a photoresist is deposited and patterned so as to cover and protect portions of the gate spacers 705, the gate dielectric 701, and the gate electrode 703 while exposing other portions. Once protected, portions of the source / drain contacts 707 can be exposed using an etching process such as a reactive ion etching process. However, any suitable process can be used to expose the source / drain contacts 707 for further processing, such as forming an overlying metallization layer.

[0077] By utilizing a non-destructive thinning process 501 to perform the final thinning step and obtain the operating layer 503, any damaged carbon nanotubes 101 can be removed from the structure and will not be present to potentially interfere with subsequent manufacturing processes. In addition, this process allows for a greater degree of control over the thinning process, allowing for very precise determination of how the carbon nanotube layer 101 is used. All of these benefits help increase yields and make the process more efficient by preventing possible defects and resulting in devices with improved performance to achieve the goal of exceeding the 2nm node.

[0078] In an embodiment, a method of manufacturing a semiconductor device, the method comprising: forming a nanotube stack, wherein each nanotube is aligned with adjacent nanotubes; depositing a support layer over the nanotube stack; removing the support layer, wherein removing the support layer also removes at least one layer of nanotubes from the nanotube stack; and depositing a gate electrode on the remaining portion of the nanotube stack. In an embodiment, the method further comprises removing a spacer material from around at least one nanotube within the remaining portion of the nanotube stack after removing the support layer. In an embodiment, forming the nanotube stack comprises filtering each nanotube through a filter membrane. In an embodiment, the filter membrane has a first electrostatic field during filtering each nanotube. In an embodiment, during filtering each nanotube, each nanotube is surrounded by a spacer material, and the spacer material has a second electrostatic field. In an embodiment, the nanotube stack has a nanotube density of about 500 nanotubes / micrometer. In an embodiment, the spacer material comprises a surfactant.

[0079] In another embodiment, a method for manufacturing a semiconductor device includes: filtering a carbon nanotube solution through a filter membrane, the filter membrane having an electrostatic field, wherein during the filtering, a first layer of carbon nanotubes, a second layer of carbon nanotubes, and a third layer of carbon nanotubes are deposited on the filter membrane; transferring the first layer of carbon nanotubes, the second layer of carbon nanotubes, and the third layer of carbon nanotubes to a dielectric layer above a substrate; removing the third layer of carbon nanotubes using a destructive removal process; removing the second layer of carbon nanotubes using a non-destructive removal process; and forming a gate electrode above the first layer of carbon nanotubes after removing the second layer of carbon nanotubes. In an embodiment, the destructive removal process includes a reactive ion etching process. In an embodiment, the non-destructive removal process includes a mechanical stripping process. In an embodiment, the mechanical stripping process also includes depositing a support layer above the second layer of carbon nanotubes, and wherein the mechanical stripping process removes the support layer and the second layer of carbon nanotubes. In an embodiment, the mechanical stripping process also removes carbon nanotubes damaged during the destructive removal process. In an embodiment, the method also includes removing spacer material from carbon nanotubes within the first layer of carbon nanotubes. In an embodiment, the first layer of carbon nanotubes has a density of about 500 nanotubes / micrometer.

[0080] In yet another embodiment, a method for manufacturing a semiconductor device includes: receiving a solution containing carbon nanotubes; aligning the carbon nanotubes into an aligned carbon nanotube stack using a first electrostatic field; placing the aligned carbon nanotube stack on a dielectric material; thinning the aligned carbon nanotube stack for a first time using a first process; thinning the aligned carbon nanotube stack for a second time using a second process different from the first process; and after thinning the aligned carbon nanotube stack for the second time, depositing a source / drain contact electrically connected to the aligned carbon nanotube stack. In an embodiment, after thinning the aligned carbon nanotube stack for the second time, the thickness of the aligned carbon nanotube stack is less than 2 nm. In an embodiment, the first process is an etching process. In an embodiment, the second process is a stripping process. In an embodiment, the first electrostatic field is generated by a material located on a filter membrane. In an embodiment, during the process of aligning the carbon nanotubes, the carbon nanotubes are surrounded by a spacer material, and the spacer material generates a second electrostatic field.

[0081] The foregoing summarizes the components of several embodiments so that those skilled in the art can better understand the various aspects of the present invention. Those skilled in the art should understand that the present invention can be easily used as a basis to design or modify other processes and structures that are used to achieve the same purposes and / or achieve the same advantages as the embodiments described herein. Those of ordinary skill in the art should understand that the present invention can be easily used as a basis to design or modify other processes and structures that are used to achieve the same purposes and / or achieve the same advantages as the embodiments described herein.

Claims

1. A method for manufacturing a semiconductor device, the method comprising: forming a nanotube stack wherein each nanotube is aligned with adjacent nanotubes; thinning the nanotube stack; depositing a support layer over the nanotube stack; removing the support layer, wherein removing the support layer also removes at least one layer of nanotubes from the nanotube stack and damaged nanotubes resulting from the thinning; and A gate electrode is deposited over the remainder of the nanotube stack. 2 . The method of claim 1 , further comprising, after removing the support layer, removing a spacer material surrounding the at least one nanotube from around the at least one nanotube within the remaining portion of the nanotube stack.

3. The method according to claim 1, wherein: The forming of the nanotube stack includes filtering the individual nanotubes through a filter membrane.

4. The method according to claim 3, wherein: The filter membrane has a first electrostatic field during filtering of the nanotubes.

5. The method according to claim 4, wherein: During the filtering of the nanotubes, the nanotubes are surrounded by a spacer material, and the spacer material has a second electrostatic field.

6. The method according to claim 5, wherein: The nanotube stack has a nanotube density of 500 nanotubes / micrometer.

7. The method according to claim 5, wherein: The spacer material includes a surfactant.

8. A method for manufacturing a semiconductor device, the method comprising: filtering the carbon nanotube solution through a filter membrane, the filter membrane having an electrostatic field, wherein during the filtering process, a first layer of carbon nanotubes, a second layer of carbon nanotubes, and a third layer of carbon nanotubes are deposited on the filter membrane; transferring the first layer of carbon nanotubes, the second layer of carbon nanotubes, and the third layer of carbon nanotubes to a dielectric layer above a substrate; removing the third layer of carbon nanotubes using a destructive removal process; removing the second layer of carbon nanotubes using a non-destructive removal process; and After removing the second layer of carbon nanotubes, a gate electrode is formed on the first layer of carbon nanotubes.

9. The method according to claim 8, wherein: The destructive removal process includes a reactive ion etching process.

10. The method according to claim 9, wherein: The non-destructive removal process includes a mechanical stripping process.

11. The method according to claim 10, wherein: The mechanical exfoliation process further includes depositing a support layer over the second layer of carbon nanotubes, and wherein the mechanical exfoliation process removes the support layer and the second layer of carbon nanotubes.

12. The method according to claim 11, wherein: The mechanical exfoliation process also removes the carbon nanotubes that were damaged during the destructive removal process.

13. The method of claim 8, further comprising removing spacer material from the carbon nanotubes within the first layer of carbon nanotubes.

14. The method according to claim 13, wherein: The first layer of carbon nanotubes has a density of 500 nanotubes / micrometer.

15. A method for manufacturing a semiconductor device, the method comprising: receiving a solution, the solution comprising carbon nanotubes; aligning the carbon nanotubes into aligned carbon nanotube stacks using a first electrostatic field; placing the aligned carbon nanotube stack on a dielectric material; thinning the aligned carbon nanotube stack for the first time using a first process; thinning the aligned carbon nanotube stack a second time using a second process different from the first process to remove at least one layer of carbon nanotubes and damaged carbon nanotubes generated by the first process; as well as After the second thinning of the aligned carbon nanotube stack, source / drain contacts electrically connected to the aligned carbon nanotube stack are deposited.

16. The method according to claim 15, wherein: After the second thinning of the aligned carbon nanotube stack, the thickness of the aligned carbon nanotube stack is less than 2 nm.

17. The method according to claim 15, wherein: The first process is an etching process.

18. The method according to claim 17, wherein: The second process is a lift-off process.

19. The method according to claim 15, wherein: The first electrostatic field is generated by a material located on the filter membrane.

20. The method according to claim 19, wherein: In the process of arranging the carbon nanotubes, the carbon nanotubes are surrounded by a spacer material, and the spacer material generates a second electrostatic field.

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