Thin film structure for micro-bolometer and method for fabricating the same

• US 10,371,571 B2
• Filed: 03/20/2018
• Issued: 08/06/2019
• Est. Priority Date: 05/19/2017
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology, Ulsan National Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Baek, Seung Hyub, Kil, Tae Hyeon, Kim, Sanghyeon, Choi, Won Jun, Baik, Jeong Min, Lee, Ki-Suk
• Primary Examiner(s): Gunberg, Edwin C
• Application Number:
  US15/926,366
• Publication Number:
  US 20180335341A1
• Time in Patent Office: 504 Days
• Field of Search: None
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10
• CPC Class Codes: G01J 5/024 Special manufacturing steps or sacrificial layers or layer structures
• CPC Class Codes: G01J 5/046 Materials; Selection of thermal materials
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 21/02172 the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides materials containing silicon H01L21/02123; metal silicates H01L21/02142

Abstract

Disclosed is a resistor thin film for micro-bolometer for growth of a vanadium dioxide (VO₂) thin film in tetragonal VO₂ crystal phase by deposition of VO₂ on oxide with perovskite structure and a method for fabricating the same, and the resistor thin film for micro-bolometer according to the present disclosure includes a silicon substrate, an oxide thin film with perovskite structure formed on the silicon substrate, and a VO₂ thin film in tetragonal crystal phase formed on the oxide thin film with perovskite structure.

Claims

1. A resistor thin film for micro-bolometer, comprising:

a semiconductor substrate;

an oxide thin film with perovskite structure formed on the semiconductor substrate; and

a vanadium dioxide (VO₂) thin film in tetragonal crystal phase formed on the oxide thin film with perovskite structure.

2. The resistor thin film for micro-bolometer according to claim 1, wherein the semiconductor substrate is one of a silicon substrate, a GaAs substrate, and a sapphire substrate, and

when the semiconductor substrate is a silicon substrate, a silicon oxide film is provided on the silicon substrate, and the oxide thin film with perovskite structure is formed on the silicon oxide film.

3. The resistor thin film for micro-bolometer according to claim 1, wherein the vanadium dioxide (VO₂) thin film in tetragonal crystal phase is formed with a thickness of 40 to 100 nm.

4. The resistor thin film for micro-bolometer according to claim 1, wherein the oxide thin film with perovskite structure is formed with a thickness of 5 to 20 nm.

5. The resistor thin film for micro-bolometer according to claim 1, wherein the oxide thin film with perovskite structure is made of one of CaTiO₃, LaAlO₃, BaTiO₃, SrTiO₃, SrRuO₃ and BiFeO₃.

6. The resistor thin film for micro-bolometer according to claim 1, wherein the vanadium dioxide (VO₂) thin film in tetragonal crystal phase has a temperature coefficient of resistance (TCR) absolute value of 3%/K or more and a specific resistance value of 1 Ω

cm or less.

7. A method for fabricating a resistor thin film for micro-bolometer, comprising:

preparing a semiconductor substrate;

stacking an oxide thin film with perovskite structure on the semiconductor substrate; and

forming a vanadium dioxide (VO₂) thin film in tetragonal crystal phase on the oxide thin film with perovskite structure.

8. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein in the forming of a vanadium dioxide (VO₂) thin film in tetragonal crystal phase on the oxide thin film with perovskite structure,

during deposition of vanadium dioxide (VO₂), tetragonal VO₂ crystal phase similar to a lattice structure of the oxide with perovskite structure has a preferred orientation among various crystal phases of vanadium dioxide (VO₂).

9. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the forming of a vanadium dioxide (VO₂) thin film in tetragonal crystal phase on the oxide thin film with perovskite structure uses a sputtering process in which a sputtering target is vanadium dioxide (VO_x) in monoclinic crystal phase, a process pressure is set to 5 to 20 mTorr, a process temperature is set to 200 to 500°

C., and mixed gas of O₂ and Ar is supplied into a sputtering chamber at a ratio of O₂/(Ar+O₂)=0.2 to 0.3%.

10. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the forming of a vanadium dioxide (VO₂) thin film in tetragonal crystal phase on the oxide thin film with perovskite structure uses a reactive sputtering process in which a sputtering target is vanadium metal and reactive gas including O₂ is supplied into a chamber.

11. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the oxide thin film with perovskite structure is made of one of CaTiO₃, LaAlO₃, BaTiO₃, SrTiO₃, SrRuO₃, and BiFeO₃.

12. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the vanadium dioxide (VO₂) thin film in tetragonal crystal phase is formed with a thickness of 40 to 100 nm, and the oxide thin film with perovskite structure is formed with a thickness of 5 to 20 nm.

13. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the vanadium dioxide (VO₂) thin film in tetragonal crystal phase has a temperature coefficient of resistance (TCR) absolute value of 3%/K or more and a specific resistance value of 11 Ω

cm or less.

14. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the semiconductor substrate is one of a silicon substrate, a GaAs substrate and a sapphire substrate, and

when the semiconductor substrate is a silicon substrate, a silicon oxide film is provided on the silicon substrate, and the oxide thin film with perovskite structure is formed on the silicon oxide film.

15. The method for fabricating a resistor thin film for micro-bolometer according to claim 7, wherein the stacking an oxide thin film with perovskite structure on the semiconductor substrate is performed at room temperature.