DC-DC converter and manufacturing method thereof

• US 9,224,757 B2
• Filed: 11/30/2011
• Issued: 12/29/2015
• Est. Priority Date: 12/03/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Takahashi, Kei, Ito, Yoshiaki
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): NASH, GARY A
• Application Number:
  US13/307,084
• Publication Number:
  US 20120140523A1
• Time in Patent Office: 1,490 Days
• Field of Search: 323/266, 323/269, 323/271, 323/272, 323/274, 323/276, 323284-287, 323/300, 327/403, 361/18, 361/746, 438/104
• US Class Current: 1/1
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

A DC-DC converter is driven by single high input voltage, and includes a voltage converter circuit and a control circuit. The increase of the occupied area of the DC-DC converter is suppressed. The DC-DC converter includes an input terminal to which input voltage is applied; a voltage converter circuit connected to the input terminal, and including a first transistor; a control circuit configured to control the voltage converter circuit, and including a second transistor including a silicon material in a channel formation region; and a third transistor provided between the input terminal and the control circuit, and configured to convert the input voltage into power supply voltage that is lower than the input voltage. The first transistor and the third transistor include an oxide semiconductor material in channel formation regions. The first transistor and the third transistor are stacked over the second transistor with an insulating film provided therebetween.

Claims

1. A DC-DC converter comprising:

an input terminal to which input voltage is applied;

a voltage converter circuit that is connected to the input terminal and includes a first transistor;

a control circuit that is configured to control the voltage converter circuit and includes a second transistor including a silicon film in a channel formation region; and

a third transistor that is provided between the input terminal and the control circuit and configured to convert the input voltage into power supply voltage that is lower than the input voltage,

wherein the first transistor and the third transistor are transistors including an oxide semiconductor film in channel formation regions,

wherein the oxide semiconductor films of the first transistor and the third transistor are stacked over the silicon film of the second transistor with an insulating film provided between the oxide semiconductor films of the first and third transistors and the silicon film of the second transistor, and

wherein the third transistor is configured to supply the power supply voltage to the control circuit from one of a source and a drain of the third transistor.

2. The DC-DC converter according to claim 1, wherein the oxide semiconductor films of the first transistor and the third transistor each comprise any one of an In—

Sn—

Ga—

Zn—

O-based oxide semiconductor, an In—

Ga—

Zn—

O-based oxide semiconductor, an In—

Sn—

Zn—

O-based oxide semiconductor, an In—

Al—

Zn—

O-based oxide semiconductor, a Sn—

Ga—

Zn—

O-based oxide semiconductor, an Al—

Ga—

Zn—

O-based oxide semiconductor, a Sn—

Al—

Zn—

O-based oxide semiconductor, an In—

Zn—

O-based oxide semiconductor, a Sn—

Zn—

O-based oxide semiconductor, an Al—

Zn—

O-based oxide semiconductor, a Zn—

Mg—

O-based oxide semiconductor, a Sn—

Mg—

O-based oxide semiconductor, an In—

Mg—

O-based oxide semiconductor, an In—

Ga—

O-based oxide semiconductor, an In—

O-based oxide semiconductor, a Sn—

O-based oxide semiconductor, and a Zn—

O-based oxide semiconductor.

3. The DC-DC converter according to claim 1, wherein the voltage converter circuit is a step-down voltage converter circuit.

4. The DC-DC converter according to claim 1, wherein the voltage converter circuit is a flyback voltage converter circuit.

5. The DC-DC converter according to claim 1, wherein the voltage converter circuit is a forward voltage converter circuit.

6. The DC-DC converter according to claim 1, wherein a gate of the third transistor is electrically connected to the control circuit.

7. The DC-DC converter according to claim 1, wherein a gate of the third transistor is directly connected to an output terminal of an operational amplifier included in the control circuit.

8. The DC-DC converter according to claim 1,

wherein the one of the source and the drain of the third transistor is electrically connected to the control circuit, and

wherein the other of the source and the drain of the third transistor is electrically connected to the input terminal.

9. The DC-DC converter according to claim 1,

wherein a gate of the third transistor is directly connected to an output terminal of an operational amplifier included in the control circuit, and

wherein the other of the source and the drain of the third transistor is directly connected to both the input terminal and one of a source and a drain of the first transistor.

10. A method for manufacturing a DC-DC converter, comprising the steps of:

forming a second transistor using a silicon film in a second channel formation region, over an insulating surface;

forming an insulating film covering the second transistor; and

forming a first transistor including an oxide semiconductor film in a first channel formation region and a third transistor using the oxide semiconductor film in a third channel formation region over the insulating film,

wherein a voltage converter circuit includes the first transistor,

wherein a control circuit configured to control the voltage converter circuit includes the second transistor,

wherein the third transistor is provided between an input terminal and the control circuit, and converts input voltage applied to the input terminal into power supply voltage that is lower than the input voltage,

wherein the oxide semiconductor films of the first transistor and the third transistor are stacked over the silicon film of the second transistor with the insulating film provided between the oxide semiconductor films of the first and third transistors and the silicon film of the second transistor, and

wherein the third transistor is configured to supply the power supply voltage to the control circuit from one of a source and a drain of the third transistor.

11. The method for manufacturing a DC-DC converter, according to claim 10, wherein the oxide semiconductor films of the first transistor and the third transistor each comprise any one of an In—

Sn—

Ga—

Zn—

O-based oxide semiconductor, an In—

Ga—

Zn—

O-based oxide semiconductor, an In—

Sn—

Zn—

O-based oxide semiconductor, an In—

Al—

Zn—

O-based oxide semiconductor, a Sn—

Ga—

Zn—

O-based oxide semiconductor, an Al—

Ga—

Zn—

O-based oxide semiconductor, a Sn—

Al—

Zn—

O-based oxide semiconductor, an In—

Zn—

O-based oxide semiconductor, a Sn—

Zn—

O-based oxide semiconductor, an Al—

Zn—

O-based oxide semiconductor, a Zn—

Mg—

O-based oxide semiconductor, a Sn—

Mg—

O-based oxide semiconductor, an In—

Mg—

O-based oxide semiconductor, an In—

Ga—

O-based oxide semiconductor, an In—

O-based oxide semiconductor, a Sn—

O-based oxide semiconductor, and a Zn—

O-based oxide semiconductor.

12. The method for manufacturing a DC-DC converter according to claim 10, wherein the voltage converter circuit is one of a step-down voltage converter circuit, a flyback voltage converter circuit and a forward voltage converter circuit.

13. A DC-DC converter comprising:

an input terminal to which input voltage is applied;

a voltage converter circuit that is connected to the input terminal and includes a first transistor;

a control circuit that is configured to control the voltage converter circuit and includes a second transistor including a silicon film in a channel formation region; and

a third transistor that is provided between the input terminal and the control circuit and configured to convert the input voltage into power supply voltage,

wherein the first transistor and the third transistor are transistors including an oxide semiconductor film in channel formation regions,

wherein the oxide semiconductor films of the first transistor and the third transistor are stacked over the silicon film of the second transistor with an insulating film provided between the oxide semiconductor films of the first and third transistors and the silicon film of the second transistor,

wherein the third transistor is configured to supply the power supply voltage to the control circuit from one of a source and a drain of the third transistor, and

wherein one of a source electrode and a drain electrode of the third transistor is in contact with the oxide semiconductor film of the third transistor and is provided in an opening portion of the insulating film.

14. The DC-DC converter according to claim 13, wherein the oxide semiconductor films of the first transistor and the third transistor each comprise any one of an In—

Sn—

Ga—

Zn—

O-based oxide semiconductor, an In—

Ga—

Zn—

O-based oxide semiconductor, an In—

Sn—

Zn—

O-based oxide semiconductor, an In—

Al—

Zn—

O-based oxide semiconductor, a Sn—

Ga—

Zn—

O-based oxide semiconductor, an Al—

Ga—

Zn—

O-based oxide semiconductor, a Sn—

Al—

Zn—

O-based oxide semiconductor, an In—

Zn—

O-based oxide semiconductor, a Sn—

Zn—

O-based oxide semiconductor, an Al—

Zn—

O-based oxide semiconductor, a Zn—

Mg—

O-based oxide semiconductor, a Sn—

Mg—

O-based oxide semiconductor, an In—

Mg—

O-based oxide semiconductor, an In—

Ga—

O-based oxide semiconductor, an In—

O-based oxide semiconductor, a Sn—

O-based oxide semiconductor, and a Zn—

O-based oxide semiconductor.

15. The DC-DC converter according to claim 13, wherein the voltage converter circuit is a step-down voltage converter circuit.

16. The DC-DC converter according to claim 13, wherein the voltage converter circuit is a flyback voltage converter circuit.

17. The DC-DC converter according to claim 13, wherein the voltage converter circuit is a forward voltage converter circuit.

18. The DC-DC converter according to claim 13, wherein a gate of the third transistor is electrically connected to the control circuit.

19. The DC-DC converter according to claim 13, wherein a gate of the third transistor is directly connected to an output terminal of an operational amplifier included in the control circuit.

20. The DC-DC converter according to claim 13,

wherein the one of the source and the drain of the third transistor is electrically connected to the control circuit, and

wherein the other of the source and the drain of the third transistor is electrically connected to the input terminal.

21. The DC-DC converter according to claim 13,

wherein a gate of the third transistor is directly connected to an output terminal of an operational amplifier included in the control circuit, and

wherein the other of the source and the drain of the third transistor is directly connected to both the input terminal and one of a source and a drain of the first transistor.