Fused nanocrystal thin film semiconductor and method

• US 7,622,371 B2
• Filed: 10/10/2006
• Issued: 11/24/2009
• Est. Priority Date: 10/10/2006
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Pan, Alfred, Ng, Hou T.
• Primary Examiner(s): Vu; David
• Assistant Examiner(s): CHI, SUBERR L
• Application Number:
  US11/548,230
• Publication Number:
  US 20080083950A1
• Time in Patent Office: 1,141 Days
• Field of Search: 438/149, 438/479, 438/497, 438/481, 438/486, 438/492, 438/500, 438/104, 438/493, 977/883, 977/892, 117/11, 117/16, 117/23, 117/54, 117/67, 117/68
• US Class Current: 438/500
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01L 27/1292 using liquid deposition, e.g. printing
• CPC Class Codes: H01L 29/0665 the shape of the body defining a nanostructure nanotechnology per se B82B
• CPC Class Codes: H01L 29/0673 oriented parallel to a substrate
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621
• CPC Class Codes: Y10S 977/892 Liquid phase deposition

Abstract

A thin film semiconductor and a method of its fabrication use induced crystallization and aggregation of a nanocrystal seed layer to form a merged-domain layer. The nanocrystal seed layer is deposited onto a substrate surface within a defined boundary. A reaction temperature below a boiling point of a reaction solution is employed. A thin film metal-oxide transistor and a method of its production employ the thin film semiconductor as a channel of the transistor. The merged-domain layer exhibits high carrier mobility.

Claims

1. A method of fabricating a thin film semiconductor component, the method comprising:

depositing a nanocrystal seed layer on a substrate within a defined boundary on the substrate, nanocrystals of the nanocrystal seed layer being prefabricated before depositing and arranged in a plurality of layers on the substrate; and

inducing crystallization and aggregation of the nanocrystal seed layer using a reaction solution, such that the thin film semiconductor component is formed, the induced crystallization and aggregation creating a merged-domain layer in the nanocrystal seed layer adjacent to a top surface of the thin film semiconductor component,

wherein the thin film semiconductor component is formed at a reaction temperature below a boiling point of the reaction solution.

2. The method of fabricating of claim 1, wherein the reaction solution is an aqueous solution and the reaction temperature less than 100 degrees C.

3. The method of fabricating of claim 1, further comprising:

applying a baffler layer on a surface of the substrate; and

forming a reaction well in the barrier layer, an extent of the formed reaction well defining the boundary.

4. The method of fabricating of claim 3, wherein the barrier layer is a photoresist layer that is applied to the substrate surface, the reaction well being formed in the photoresist layer.

5. The method of fabricating of claim 1, wherein depositing a nanocrystal seed layer comprises one or more of printing, spraying, spin coating, dip coating, and drop coating a carrier solution, the carrier solution comprising nanocrystals suspended in a solvent.

6. The method of fabricating of claim 5, wherein an amount of the nanocrystals in the solvent is between about 0.075 weight-percent (wt-%) to about 0.20 wt-%.

7. The method of fabricating of claim 5, further comprising evaporating the solvent following depositing a nanocrystal seed layer.

8. The method of fabricating of claim 1, wherein inducing crystallization and aggregation comprises depositing a reaction solution onto the nanocrystal seed layer, the reaction solution comprising a solvent, a pH modifier, and a crystal source material for the crystallization.

9. The method of fabricating of claim 8, wherein the nanocrystal seed layer comprises a plurality of zinc oxide (ZnO) nanocrystals, the solvent comprises water (H₂O), the pH modifier comprises hexamine, and the crystal source material comprises zinc nitrate (Zn(NO₃)₂) dissolved in the water.

10. The method of fabricating of claim 8, wherein the hexamine and Zn(NO₃)₂ have an equimolar ratio between 0.06 and 0.15 molar in the reaction solution.

11. The method of fabricating of claim 1, wherein the semiconductor component is a channel of a thin film transistor.

12. The method of fabricating of claim 1, wherein the formed thin film semiconductor component comprises a merged-domain layer resulting from the induced crystallization and aggregation of the nanocrystal seed layer.

13. A method of producing a metal-oxide thin film transistor, the method comprising:

defining a reaction well on a substrate, the reaction well establishing an extent of a channel of the metal-oxide thin film transistor;

creating a metal-oxide nanocrystal seed layer within the defined reaction well, nanocrystals of the nanocrystal seed layer being prefabricated before creating the metal-oxide nanocrystal seed layer and arranged in a plurality of layers within the reaction well; and

fusing the metal-oxide nanocrystal seed layer to form a merged-domain layer in the nanocrystal seed layer using liquid-phase deposition within the reaction well, the merged-domain layer being adjacent to a top surface of the nanocrystal seed layer,

wherein the liquid-phase deposition crystallizes and aggregates an upper portion of the metal-oxide nanocrystal seed layer into the merged-domain layer to form a thin film metal-oxide semiconductor, the thin film metal-oxide semiconductor providing the channel of the metal-oxide thin film transistor.

14. The method of producing a metal-oxide thin film transistor of claim 13, wherein the metal-oxide is zinc oxide (ZnO), the thin film transistor being a ZnO thin film transistor, and wherein a layer of the thin film metal-oxide semiconductor is a merged-domain layer.

15. The method of producing a metal-oxide thin film transistor of claim 13, wherein fusing the metal-oxide nanocrystal seed layer comprises:

depositing a reaction solution comprising a solvent, a pH modifier, and a crystal source material for the crystallization and aggregation into the reaction well on the created metal-oxide nanocrystal seed layer.

16. The method of producing a metal-oxide thin film transistor of claim 15, wherein fusing the metal-oxide nanocrystal seed layer further comprises heating the deposited reaction solution to a reaction temperature that is less than a boiling point of reaction solution.