# US 8,772,782 B2 · Transistor employing vertically stacked self-aligned carbon nanotubes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,772,782 B2 - Document ID: US8772782B2 - Status: Granted - Kind: B2 - Application number: 13/303,785 - Filed: 2011-11-23 - Published: 2013-05-23 - Granted: 2014-07-08 - Earliest claimed: 2011-11-23 - Assignees: International Business Machines Corporation - Applicants: Qing Cao; Dechao Guo; Shu-Jen Han; Yu Lu; Keith Kwong Hon Wong - Inventors: Qing Cao; Dechao Guo; Shu-Jen Han; Yu Lu; Keith Kwong Hon Wong - Web page: https://patentgrep.com/patent/US8772782B2 ## CPC - H10K 10/491: {Vertical transistors, e.g. vertical carbon nanotube field effect transistors [CNT-FETs]} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites - H10D 30/014: {of FETs having zero-dimensional [0D] or one-dimensional [1D] channels, e.g. quantum wire FETs, single-electron transistors [SET] or Coulomb blockade transistors} - H10D 30/43: having one-dimensional [1D] charge carrier gas channels, e.g. quantum wire FETs or transistors having 1D quantum-confined channels - H10D 30/63: Vertical IGFETs (H10D30/66 {, H10D30/6728, H10D30/689, H10D30/693} take precedence) - H10D 62/813: {Quantum wire structures} - H10K 85/20: Carbon compounds, e.g. carbon nanotubes or fullerenes - H10K 85/221: {Carbon nanotubes} - Y10S 977/742: Carbon nanotubes, CNTs - Y10S 977/842: for carbon nanotubes or fullerenes - Y10S 977/938: Field effect transistors, FETS, with nanowire- or nanotube-channel region - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A fin structure including a vertical alternating stack of a first isoelectric point material layer having a first isoelectric point and a second isoelectric material layer having a second isoelectric point less than the first isoelectric point is formed. The first and second isoelectric point material layers become oppositely charged in a solution with a pH between the first and second isoelectric points. Negative electrical charges are imparted onto carbon nanotubes by an anionic surfactant to the solution. The electrostatic attraction causes the carbon nanotubes to be selectively attached to the surfaces of the first isoelectric point material layer. Carbon nanotubes are attached to the first isoelectric point material layer in self-alignment along horizontal lengthwise directions of the fin structure. A transistor can be formed, which employs a plurality of vertically aligned horizontal carbon nanotubes as the channel. ## Claims ### Claim 1 A structure comprising: a fin structure located on a substrate, having a length in a lengthwise direction and a width in a widthwise direction, and comprising at least one pair of layers, wherein each pair of layers within said at least one pair of layers includes a first isoelectric point material layer having a first isoelectric point and a second isoelectric point material layer having a second isoelectric point that is different from said first isoelectric point; carbon nanotubes located on lengthwise sidewalls of said at least one first isoelectric point material layer, wherein at least one second isoelectric point material layer is not in contact with a surface of any carbon nanotube; a gate dielectric contacting a portion of lengthwise sidewalls of said fin structure; and a gate conductor overlying said gate dielectric. ### Claim 2 (depends on 1) The structure of claim 1, wherein said carbon nanotubes are oriented along said horizontal lengthwise direction. ### Claim 3 (depends on 1) The structure of claim 1, wherein widthwise sidewalls of said fin structure are not in contact with any carbon nanotube. ### Claim 4 (depends on 1) The structure of claim 1, wherein said first isoelectric point is greater than said second isoelectric point. ### Claim 5 (depends on 4) The structure of claim 4, wherein said first isoelectric point material layer includes a material selected from silicon nitride and a dielectric metal oxide, and said second isoelectric point material layer includes silicon oxide. ### Claim 6 (depends on 4) The structure of claim 4, wherein said first isoelectric point is greater than said second isoelectric point by at least 2.0. ### Claim 7 (depends on 1) The structure of claim 1, wherein said width is less than ½ of said length, and each of said at least one first isoelectric point material layer has a height that is less than ½ of said length. ### Claim 8 (depends on 1) The structure of claim 1, wherein said width is less than 1/10 of said length, and each of said at least one first isoelectric point material layer has a height that is less than 1/10 of said length. ### Claim 9 (depends on 1) The structure of claim 1, wherein said at least one pair of layers is a plurality of pairs of layers that constitute an alternating stack of said first isoelectric point material layer and said second isoelectric point material layer. ### Claim 10 (depends on 9) The structure of claim 9, wherein each first isoelectric point material layer has first lengthwise sidewalls and each second isoelectric point material layer has second lengthwise sidewalls, wherein said first lengthwise sidewalls and said second lengthwise sidewalls are located within two parallel vertical planes. ### Claim 11 (depends on 9) The structure of claim 9, wherein each first isoelectric point material layer has first lengthwise sidewalls and each second isoelectric point material layer has second lengthwise sidewalls, wherein said first lengthwise sidewalls and said second lengthwise sidewalls are laterally offset by an offset distance. ### Claim 12 (depends on 9) The structure of claim 9, wherein said first isoelectric point is greater than said second isoelectric point by at least 2.0. ### Claim 13 (depends on 1) The structure of claim 1, wherein each of said carbon nanotubes has a sidewall that is in contact with one of said lengthwise sidewalls. ### Claim 14 A structure comprising: a fin structure located on a substrate, having a length in a lengthwise direction and a width in a widthwise direction, and comprising at least one pair of layers, wherein each pair of layers within said at least one pair of layers includes a first isoelectric point material layer having a first isoelectric point and a second isoelectric point material layer having a second isoelectric point that is different from said first isoelectric point; carbon nanotubes located on lengthwise sidewalls of said at least one first isoelectric point material layer wherein at least one second isoelectric point material layer is not in contact with a surface of any carbon nanotube; a gate dielectric contacting a portion of lengthwise sidewalls of said fin structure; a gate conductor overlying said gate dielectric; a source-side contact structure in contact with said carbon nanotubes at one side of said gate conductor; and a drain-side contact structure in contact with said carbon nanotubes at another side of said gate conductor. ### Claim 15 (depends on 14) The structure of claim 14, wherein said carbon nanotubes are oriented along said horizontal lengthwise direction. ### Claim 16 (depends on 14) The structure of claim 14, wherein widthwise sidewalls of said fin structure are not in contact with any carbon nanotube. ### Claim 17 (depends on 14) The structure of claim 14, wherein said first isoelectric point is greater than said second isoelectric point. ### Claim 18 (depends on 17) The structure of claim 17, wherein said first isoelectric point material layer includes a material selected from silicon nitride and a dielectric metal oxide, and said second isoelectric point material layer includes silicon oxide. ### Claim 19 (depends on 17) The structure of claim 17, wherein said first isoelectric point is greater than said second isoelectric point by at least 2.0. ### Claim 20 (depends on 14) The structure of claim 14, wherein said width is less than ½ of said length, and each of said at least one first isoelectric point material layer has a height that is less than ½ of said length. ### Claim 21 (depends on 14) The structure of claim 14, wherein said width is less than 1/10 of said length, and each of said at least one first isoelectric point material layer has a height that is less than 1/10 of said length. ### Claim 22 (depends on 14) The structure of claim 14, wherein said at least one pair of layers is a plurality of pairs of layers that constitute an alternating stack of said first isoelectric point material layer and said second isoelectric point material layer. ### Claim 23 (depends on 22) The structure of claim 22, wherein each first isoelectric point material layer has first lengthwise sidewalls and each second isoelectric point material layer has second lengthwise sidewalls, wherein said first lengthwise sidewalls and said second lengthwise sidewalls are located within two parallel vertical planes. ### Claim 24 (depends on 22) The structure of claim 22, wherein each first isoelectric point material layer has first lengthwise sidewalls and each second isoelectric point material layer has second lengthwise sidewalls, wherein said first lengthwise sidewalls and said second lengthwise sidewalls are laterally offset by an offset distance. ### Claim 25 (depends on 14) The structure of claim 14, wherein each of said carbon nanotubes has a sidewall that is in contact with one of said lengthwise sidewalls.