# US 2008/0185626 A1 · Trench capacitor and method for fabricating the same

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- Number: US 2008/0185626 A1
- Document ID: US20080185626A1
- Status: Published application
- Kind: A1
- Application number: 12/062,310
- Filed: 2008-04-03
- Published: 2008-08-07
- Earliest claimed: 2006-04-27
- Assignees: International Business Machines Corporation
- Inventors: Kangguo Cheng
- Web page: https://patentgrep.com/patent/US20080185626A1

## CPC

- H10D 1/047: {of conductor-insulator-semiconductor capacitors, e.g. trench capacitors}
- A01N 25/08: containing solids as carriers or diluents
- A01N 25/12: Powders or granules (A01N25/26 takes precedence)
- A01N 59/00: Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
- A01N 59/06: Aluminium; Calcium; Magnesium; Compounds thereof
- A01N 59/20: Copper
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS

## Abstract

A trench capacitor with an isolation collar in a semiconductor substrate where the substrate adjacent to the isolation collar is free of dopants caused by auto-doping. The method of fabricating the trench capacitor includes the steps of forming a trench in the semiconductor substrate; depositing a dielectric layer on a sidewall of the trench; filling the trench with a first layer of undoped polysilicon; etching away the first layer of undoped polysilicon and the dielectric layer from an upper section of the trench whereby the semiconductor substrate is exposed at the sidewall in the upper section of the trench; forming an isolation collar layer on the sidewall in the upper section of the trench; and filling the trench with a second layer of doped polysilicon.

## Claims

### Claim at position 1

1-17. (canceled)

### Claim 18

A semiconductor device comprising a semiconductor substrate, said substrate having at least one trench capacitor formed therein, the trench capacitor having an isolation collar, wherein the substrate adjacent to the isolation collar is free of dopants caused by auto-doping.

### Claim 19 (depends on 18)

The semiconductor device of claim 18, wherein the trench capacitor comprises a first polysilicon layer disposed in a lower section of the trench capacitor, and a second polysilicon layer in the upper section of the trench capacitor.

### Claim 20 (depends on 18)

The semiconductor device of claim 18, wherein the trench capacitor comprises a first polysilicon layer, said first polysilicon layer having an open cavity therein, and a second polysilicon layer, said second polysilicon layer filling said open cavity.