Normally-off gallium oxide field-effect transistor

• US 10,644,107 B1
• Filed: 08/14/2018
• Issued: 05/05/2020
• Est. Priority Date: 10/20/2017
• Status: Active Grant

• Current Assignee: Synopsys Incorporated
• Original Assignee: Synopsys Incorporated
• Inventors: Wong, Hiu Yung, de Almeida Braga, Nelson, Mickevicius, Rimvydas
• Primary Examiner(s): Hossain, Moazzam
• Assistant Examiner(s): Isaac, Stanetta D
• Application Number:
  US16/103,805
• Time in Patent Office: 630 Days
• Field of Search: None
• CPC Class Codes: H01L 29/1037 and non-planar channel resulting from the gate electrode disposition, e.g. within a trench, H01L29/42356
• CPC Class Codes: H01L 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/785 having a channel with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET

Abstract

The independent claims of this patent signify a concise description of embodiments. Disclosed herein is a normally-off, gallium oxide field-effect transistor. The field-effect transistor comprises a source, a source spacer, a first channel region, a second channel region, a drain spacer, and a drain. The source, the source spacer, the first channel region, the second channel region, the drain spacer, and the drain are of a first conductivity type. All the regions have the same type of doping. The field-effect transistor further includes a gate dielectric over the channel body and a gate over the gate dielectric. The first channel region has a cross-sectional area that is smaller than the second channel region.

Claims

1. A field-effect transistor comprising:

a source, a channel body, and a drain of a first conductivity type; and

a gate dielectric over the channel body; and

a gate over the gate dielectric,

wherein the channel body comprises in longitudinal sequence;

a source spacer, a first channel region, a second channel region, and a drain spacer, the first channel region having a cross-sectional area that is smaller than that of the second channel region, the cross-sectional areas of the first and second channel regions being orthogonal to a direction of current flow between the source and the drain.

2. The field-effect transistor of claim 1, the drain spacer and the source spacer have the cross-sectional area of the second channel region.

3. The field-effect transistor of claim 1, wherein the field-effect transistor is off when there is a voltage difference between the source and the drain and there is no voltage applied between the gate and the source or the gate and the drain.

4. The field-effect transistor of claim 1, wherein the first channel region has a first length and the second channel region has a second length;

and

wherein the first length is shorter than the second length.

5. The field-effect transistor of claim 1, wherein the channel body has a doping concentration;

and

wherein a threshold voltage of the field-effect transistor is dependent upon the doping concentration of the channel body and the cross-sectional area of the first channel region.

6. The field-effect transistor of claim 1, wherein the channel body and the source and drain spacers have a doping concentration;

and

wherein a current between the source and the drain when there is a voltage applied at the gate of the field-effect transistor is dependent upon the doping concentration of the channel body and the source and drain spacers and the cross-sectional area of the first channel region.

7. The field-effect transistor of claim 1 is a fin field-effect transistor.

8. The field-effect transistor of claim 1, wherein the first conductivity type is n-type doping.

9. A fin field-effect transistor comprising:

a source, a channel body, and a drain of a first conductivity type; and

a gate dielectric over the channel body; and

a gate over the gate dielectric,

wherein the channel body comprises in longitudinal sequence;

a source spacer, a first channel region, a second channel region, and a drain spacer, the first channel region having a cross-sectional area that is smaller than that of the second channel region, the cross-sectional areas of the first and second channel regions being orthogonal to a direction of current flow between the source and the drain.

10. The fin field-effect transistor of claim 9, the drain spacer and the source spacer have the cross-sectional area of the second channel region.

11. The fin field-effect transistor of claim 9, wherein the source, the source spacer, the first and second channel regions, the drain spacer, and the drain each comprise gallium oxide.

12. The fin field-effect transistor of claim 9, wherein the fin field-effect transistor is off when there is a voltage difference between the source and the drain and there is no voltage applied between the gate and the source or the gate and the drain.

13. The fin field-effect transistor of claim 9, wherein the first channel region has a first length and the second channel region has a second length;

and

wherein the first length is shorter than the second length.

14. The fin field-effect transistor of claim 9, wherein the channel body has a doping concentration;

and

wherein a threshold voltage of the fin field-effect transistor is dependent upon the doping concentration of the channel body and the cross-sectional area of the first channel region.

15. The fin field-effect transistor of claim 9, wherein the channel body has a doping concentration;

and

wherein a current between the source and the drain when there is a voltage applied at the gate of the fin field-effect transistor is dependent upon the doping concentration of the channel body and the cross-sectional area of the first channel region.

16. The fin field-effect transistor of claim 9, wherein the first conductivity type is n-type doping.

17. A field-effect transistor comprising:

a source, a channel body, and a drain of a first conductivity type; and

a gate dielectric over the channel body; and

a gate over the gate dielectric,

wherein the channel body comprises in longitudinal sequence;

a source spacer, a first channel region, a second channel region, and a drain spacer, the first channel region having a cross-sectional area that is smaller than that of the second channel region, the cross-sectional areas of the first and second channel regions being orthogonal to a direction of current flow between the source and the drain,

and wherein the source, the source spacer, the first and second channel regions, the drain spacer, and the drain each comprise gallium oxide.

18. The field-effect transistor of claim 17, the drain spacer and the source spacer have the cross-sectional area of the second channel region.

19. The field-effect transistor of claim 17, wherein the field-effect transistor is off when there is a voltage difference between the source and the drain and there is no voltage applied between the gate and the source or the gate and the drain.

20. The field-effect transistor of claim 17, wherein the first channel region has a first length and the second channel region has a second length;

and

wherein the first length is shorter than the second length.

21. The field-effect transistor of claim 17, wherein the channel body has a doping concentration;

and

wherein a threshold voltage of the field-effect transistor is dependent upon the doping concentration of the channel body and the cross-sectional area of the first channel region.

22. The field-effect transistor of claim 17, wherein the channel body and the source and drain spacers have a doping concentration;

and

wherein a current between the source and the drain when there is a voltage applied at the gate of the field-effect transistor is dependent upon the doping concentration of the channel body and the source and drain spacers and the cross-sectional area of the first channel region.

23. The field-effect transistor of claim 17 is a fin field-effect transistor.

24. The field-effect transistor of claim 17, wherein the first conductivity type is n-type doping.