Browse Prior Art Database

High Capacitance Tungsten to Metal 1 Capacitor for High Frequency Applications

IP.com Disclosure Number: IPCOM000114995D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 93K

Publishing Venue

IBM

Related People

Johnson, BD: AUTHOR [+6]

Abstract

A method to fabricate a high density capacitor and integrate it into an existing Complementary Metal Oxide Semiconductor (CMOS) or BiCMOS wafer process is disclosed. This new capacitor has minimal substrate coupling and is designed to be used in high frequency applications without adversely perturbating other transistor forming process steps.

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High Capacitance Tungsten to Metal 1 Capacitor for High Frequency
Applications

      A method to fabricate a high density capacitor and integrate it
into an existing Complementary Metal Oxide Semiconductor (CMOS) or
BiCMOS wafer process is disclosed.  This new capacitor has minimal
substrate coupling and is designed to be used in high frequency
applications without adversely perturbating other transistor forming
process steps.

      This new capacitor technique simplifies process integration
and allows for enhancements to an existing process without the
complexities associated with capacitors requiring added polysilicon
levels that result in adverse coupling to the semiconductor
substrate.

      The tungsten to metal 1 (M1) capacitor can be integrated into a
CMOS or BICMOS process after the Contact (CA) tungsten chemical
mechanical polish step.  The process requires five additional steps
from the Process of Record (POR) and utilizes the existing tool set.

      The first step is the definition of the tungsten, which acts as
the bottom plate of the capacitor.  The desired pattern is printed on
the wafer with standard photolithography techniques.  The CA oxide is
Reactive Ion Etched (RIE) to the correct depth.  The photoresist is
stripped to leave a well where the tungsten will be applied (Fig. 1).

      The second step is tungsten deposition.  The tungsten is
deposited uniformly over the entire wafer, filling in the wells
previously defined.  The thickness of tungsten deposited will depend
on the initial depth of the lower plate well.

      The third step involves the Chemical Mechanical Polishing (CMP)
of the tungsten...