MOS control diode and method for manufacturing the same

• US 20020088989A1
• Filed: 01/28/2002
• Published: 07/11/2002
• Est. Priority Date: 09/10/1997
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Ho-Hyun
• Granted Patent: US 6,674,123 B2
• Time in Patent Office: Days
• US Class Current: 257/135
• CPC Class Codes: H01L 29/7391 Gated diode structures
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/861 Diodes

Abstract

A MOS control diode is provided for power switching. In the MOS control diode, a switching speed is high and a reverse leakage current characteristic is improved without additionally needing processes for improving reverse recovery time by converting a power MOSFET which is a majority carrier device to diode having two terminals. Such a MOS control diode can be achieved by forming a discontinuous area in a gate oxide film formed on the surface of a semiconductor substrate so that the conductive gate electrode is connected to the semiconductor substrate. Also, it is possible to form a trench in the semiconductor substrate, to form the gate oxide films on the sidewall of a trench, and to connect the gate electrode to the semiconductor substrate through the bottom of the trench.

Claims

1. A MOS control trench type diode, comprising:

a semiconductor substrate having a first conductive type as a drain area;

a base well area having a second conductive type electrically coupled to the drain area;

a source well area having a first conductive type formed on the base well area;

a trench extending through the source well area, the base well area and a part of the semiconductor substrate;

a gate electrode formed in the trench, insulated from the base well area, and electrically coupled to the substrate.

2. The trench type MOS control diode of claim 1, wherein the gate electrode is insulated from the base well area and the source well area by a gate oxide film formed on sidewall of the trench.

3. The trench type MOS control diode of claim 1, further comprising, an insulating film formed on the semiconductor substrate so as to cover the entire top side of the gate electrode and to expose some of the source well;

and

a source electrode formed on the exposed source well and the insulating film so as to cover the semiconductor substrate.

4. The trench type MOS control diode of claim 1, wherein the gate electrode is formed of a composite layer consisting of a polysilicon layer formed on the sidewall and the bottom of the trench to a predetermined thickness and a metal layer which fills the trench.

5. The trench type MOS control diode of claim 3, wherein the insulating film is formed of SiO2.

6. The trench type MOS control diode of claim 1, wherein a plurality of the gate electrodes are formed in a plurality of the trenches.

7. The trench type MOS control diode of claim 1, further comprising a drain electrode formed on a backside of the semiconductor substrate.

8. The trench type MOS control diode of claim 1, wherein the first conductive type is N type and the second conductive type is P type.