Transistor having narrow trench filled with epitaxially-grown filling material free of voids

• US 7,230,298 B2
• Filed: 07/18/2002
• Issued: 06/12/2007
• Est. Priority Date: 08/30/2001
• Status: Expired due to Term

• Current Assignee: Shindengen Electric Manufacturing Company Limited
• Original Assignee: Shindengen Electric Manufacturing Company Limited
• Inventors: Sugai, Akihiko, Kunori, Shinji, Oshima, Kosuke, Kitada, Mizue, Kurosaki, Toru
• Primary Examiner(s): Nadav; Ori
• Application Number:
  US10/197,565
• Publication Number:
  US 20030042555A1
• Time in Patent Office: 1,790 Days
• Field of Search: 257/302, 257/327, 257328-343, 257/401, 257/402, 438/259, 438/270, 438/271, 438/284, 438/286, 438/299, 438/589
• US Class Current: 257/332
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• CPC Class Codes: H01L 29/66143 Schottky diodes
• CPC Class Codes: H01L 29/66348 with a recessed gate
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A transistor and diode having a low resistance and a high breakdown voltage are provided. When the bottom portion of a narrow trench having the shape of a rectangular parallelepiped is filled with a semiconductor grown by epitaxial method, a {1 0 0} plane is exposed at the sidewalls of the narrow trench. The semiconductor is epitaxially grown at a constant rate on each sidewall of the narrow trench; thereby, creating a filling material with no voids present therein. The concentration and width of the filling material are optimized. This allows the portion located between the filling materials in a drain layer to be completely depleted when the filling material is completely depleted; thereby, making it possible to establish an electric field having a constant strength in the depletion layer extended in the drain layer.

Claims

1. A transistor comprising:

a single crystal substrate having a {100} plane surface, said surface being defined by an x-axis and an orthogonal y-axis, the x and y axes coinciding with crystallographic axes of said single crystal;

a drain layer of a first conductivity type epitaxially grown on the surface of said single crystal substrate, so as to have a crystal structure oriented similar to said single crystal substrate;

a body layer of a second conductivity type, said body layer disposed in contact with said drain layer;

a narrow trench having a bottom parallel to the surface of the substrate and sidewalls perpendicular to the bottom and having a bottom with endwalls and sidewalls extending upward, formed across said body layer and said drain layer with the bottom and a portion of the sidewalls and the end walls disposed in said drain layer, the sidewalls of said narrow trench being aligned with one of the x-axis and y-axis so as to expose the bottom and the portion of the sidewalls to a {100} plane of said drain layer crystal structure,

a source region disposed at an opening of said narrow trench in the body layer and spaced apart from said drain layer;

a filling material, substantially free of voids, and doped with a dopant of the second conductivity type, formed of an epitaxially grown semiconductor in said narrow trench, said filling material having a bottom portion, side portions and end portions in contact with the bottom, sidewalls and endwalls of said narrow trench, and a top portion located below an interface between said body layer and said drain layer, the epitaxially grown semiconductor of said filling material being exposed to {100} planes of said drain layer crystal structure and thus having a crystal structure oriented similar to the drain layer'"'"'s crystal structure;

a gate film formed at least on a portion, at which the body layer is exposed, of sidewalls of said narrow trench; and

a gate electrode plug, disposed in contact with said gate insulating film in said narrow trench, and electrically insulated from said filling material.

2. The transistor according to claim 1, wherein the filling material is maintained at a floating potential, said filling material having a gate insulating film thereon.

3. The transistor according to claim 1, wherein the filling material is electrically connected to the source region.

4. The transistor according to claim 1, further comprising:

a semiconductor substrate of the first conductivity type on a surface of the drain layer, the surface being opposite to a surface having the body layer located therein; and

a drain electrode formed on a surface of the semiconductor substrate, the drain electrode providing an ohmic contact to the semiconductor substrate.

5. The transistor according to claim 1, further comprising:

a collector layer of the second conductivity type on a surface of the drain layer, the surface being opposite to a surface having the body layer located therein, and

a collector electrode formed on a surface of the collector layer, the collector electrode providing an ohmic contact to the collector layer.

6. The transistor according to claim 1, wherein a Schottky electrode forming a Schottky junction with the drain layer is provided on a surface of the drain layer, the surface being opposite to a surface having the body layer located therein.

7. The transistor according to claim 1, further comprising a source electrode film, the source electrode film being electrically insulated from the gate electrode plug by an interlayer insulation film.

8. The transistor according to claim 1, further comprising a gate electrode film connected to the electrode plug, a voltage applied to the gate electrode film also being applied to the gate electrode plug in the narrow trench.

9. The transistor according to claim 1, wherein an electric field has a substantially constant strength in a depletion layer extended in the drain layer between the narrow trenches.