Configurations and methods for manufacturing charged balanced devices

• US 9,876,072 B2
• Filed: 06/14/2016
• Issued: 01/23/2018
• Est. Priority Date: 01/08/2006
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Hbert, Franois
• Primary Examiner(s): DANG, PHUC T
• Application Number:
  US15/182,416
• Publication Number:
  US 20160351658A1
• Time in Patent Office: 588 Days
• CPC Class Codes: H01L 21/26513 of electrically active species
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• 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 29/0878 Impurity concentration or distribution
• CPC Class Codes: H01L 29/0886 Shape
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

This invention discloses a semiconductor power device disposed in a semiconductor substrate and the semiconductor substrate has a plurality of deep trenches. The deep trenches are filled with an epitaxial layer thus forming a top epitaxial layer covering areas above a top surface of the deep trenches covering over the semiconductor substrate. The semiconductor power device further includes a plurality of transistor cells disposed in the top epitaxial layer whereby a device performance of the semiconductor power device is dependent on a depth of the deep trenches and not dependent on a thickness of the top epitaxial layer. Each of the plurality of transistor cells includes a trench DMOS transistor cell having a trench gate opened through the top epitaxial layer and filled with a gate dielectric material.

Claims

1. A semiconductor power device supported in a uniformly doped substrate of a first conductivity type;

wherein the semiconductor power comprising;

deep trenches etched into the uniformly doped substrate wherein the uniformly doped substrate lateral to the deep trenches constituting a drift region for the semiconductor power device;

an epitaxial layer of a second conductivity type filling the deep trenches to charge balance the drift region, wherein the epitaxial layer filling the deep trenches and forming a top thin epitaxial layer over the top surface of the semiconductor substrate;

a highly doped drain region of the first conductivity type disposed at the bottom of the semiconductor substrate wherein the drain region contacts a drain metal electrode disposed at a backside of the semiconductor substrate below the drain region;

a plurality of trench MOSFET cells each having a trenched gate opened from the top epitaxial layer of the second conductivity type filled with a gate material and extends into the semiconductor regions between the deep trenches with the top epitaxial layer of the second conductivity type functioning as the body region encompassing doped regions of the first conductivity type functioning as source regions and

each of the trench MOSFET cells having shallow trench gate sidewall dopant regions surrounding sidewalls of the trenched gate and a gate-bottom dopant region below the trenched gate, wherein the gate sidewall dopant regions and gate-bottom dopant regions are of the first conductivity type.

8. The semiconductor power device of claim 1 wherein:

a bottom of the deep trenches reaches to a depth above the bottom substrate.

2. A semiconductor power device supported in a uniformly doped substrate of a first conductivity type;

wherein the semiconductor power comprising;

deep trenches etched into the uniformly doped substrate wherein the uniformly doped substrate lateral to the deep trenches constituting a drift region for the semiconductor power device;

an epitaxial layer of a second conductivity type filling the deep trenches to charge balance the drift region, wherein the epitaxial layer filling the deep trenches and forming a top thin epitaxial layer over the top surface of the semiconductor substrate;

a highly doped drain region of the first conductivity type disposed at the bottom of the semiconductor substrate wherein the drain region contacts a drain metal electrode disposed at a backside of the semiconductor substrate below the drain region;

a plurality of trench MOSFET cells each having a trenched gate opened from the top epitaxial layer of the second conductivity type filled with a gate material and extends into the semiconductor regions between the deep trenches with the top epitaxial layer of the second conductivity type functioning as the body region encompassing doped regions of the first conductivity type functioning as source regions and

each of the trench MOSFET cells having shallow trench gate sidewall dopant regions surrounding sidewalls of the trenched gate and a gate-bottom dopant region below the trenched gate, wherein the gate sidewall dopant regions and gate-bottom dopant regions are of an N-type conductivity type.

3. A semiconductor power device supported in a uniformly doped substrate of a first conductivity type;

wherein the semiconductor power comprising;

deep trenches etched into the uniformly doped substrate wherein the uniformly doped substrate lateral to the deep trenches constituting a drift region for the semiconductor power device;

an epitaxial layer of a second conductivity type filling the deep trenches to charge balance the drift region, wherein the epitaxial layer filling the deep trenches and forming a top thin epitaxial layer over the top surface of the semiconductor substrate;

a highly doped drain region of the first conductivity type disposed at the bottom of the semiconductor substrate wherein the drain region contacts a drain metal electrode disposed at a backside of the semiconductor substrate below the drain region;

a plurality of trench MOSFET cells each having a trenched gate opened from the top epitaxial layer of the second conductivity type filled with a gate material and extends into the semiconductor regions between the deep trenches with the top epitaxial layer of the second conductivity type functioning as the body region encompassing doped regions of the first conductivity type functioning as source regions and

the semiconductor regions between said deep trenches having a laterally gradient dopant concentration gradually decreasing from a region immediately next to sidewalls of the deep trenches.

4. A semiconductor power device supported in a uniformly doped substrate of a first conductivity type;

wherein the semiconductor power comprising;

deep trenches etched into the uniformly doped substrate wherein the uniformly doped substrate lateral to the deep trenches constituting a drift region for the semiconductor power device;

an epitaxial layer of a second conductivity type filling the deep trenches to charge balance the drift region, wherein the epitaxial layer filling the deep trenches and forming a top thin epitaxial layer over the top surface of the semiconductor substrate;

a highly doped drain region of the first conductivity type disposed at the bottom of the semiconductor substrate wherein the drain region contacts a drain metal electrode disposed at a backside of the semiconductor substrate below the drain region;

a plurality of trench MOSFET cells each having a trenched gate opened from the top epitaxial layer of the second conductivity type filled with a gate material and extends into the semiconductor regions between the deep trenches with the top epitaxial layer of the second conductivity type functioning as the body region encompassing doped regions of the first conductivity type functioning as source regions and

the semiconductor regions between said deep trenches having a laterally gradient dopant concentration of an N-type conductivity type gradually decreasing from a region immediately next to sidewalls of the deep trenches filled with the epitaxial layer of a P-type conductivity.

5. A semiconductor power device comprising:

a semiconductor substrate including deep trenches;

a single epitaxial layer fills the deep trenches and having a top epitaxial layer covering over a top surface of the semiconductor substrate above the deep trenches;

a plurality of trench transistor cells disposed in the top epitaxial layer with the semiconductor substrate lateral to the deep trenches functioning as a drift region of the transistor cells and wherein each of the trench transistor comprises a trench gate opened in the top epitaxial layer and extended into the drift region between the deep trenches;

the epitaxial layer in the deep trenches charge balances the drift region of the semiconductor substrate surrounding the deep trenches; and

the trench gate further comprises gate sidewall dopant regions surrounding sidewalls of said trench gate and a gate-bottom dopant region below the trench gate, wherein the gate sidewall dopant regions and gate-bottom dopant regions are of a same conductivity type as the semiconductor substrate.

6. The semiconductor power device of claim 5 wherein:

each of said trench gates is filled with a gate dielectric material.

7. The semiconductor power device of claim 5 wherein:

a bottom of the deep trenches reaches the bottom substrate.