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RESISTANCE REDUCER FOR FOCUSED ION BEAM VAPOR DEPOSITION

IP.com Disclosure Number: IPCOM000007179D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2002-Mar-04
Document File: 4 page(s) / 276K

Publishing Venue

Motorola

Related People

David H. Perrin: AUTHOR [+2]

Abstract

The present technology of Focused Ion Beam deposition of a metal film, uses liquid gallium as the source of positively charged ions that are accel- erated and focused to form a high-resolution beam. The beam can cut openings in the surface (cross- section) and additionally, using a gas injection sys- tem, a metal film such as tungsten or platinum can be selectively deposited onto the device surface where electrical connection between conductors is desired, Figure 1.

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Technical Developments Volume 22 June 1994

RESISTANCE REDUCER FOR FOCUSED ION BEAM VAPOR DEPOSITION

by David H. Perrin and Wayland C. Seifert

text and illustrated in Figure 2. Figures 3 shows SEM photomicrographs ofactual enhanced modifications.

PROBLEM DEFINITION

  The present technology of Focused Ion Beam deposition of a metal film, uses liquid gallium as the source of positively charged ions that are accel- erated and focused to form a high-resolution beam. The beam can cut openings in the surface (cross- section) and additionally, using a gas injection sys- tem, a metal film such as tungsten or platinum can be selectively deposited onto the device surface where electrical connection between conductors is desired, Figure 1.

  Focused Ion Beam metal depositions are typi- cally done with tungsten or platinum compounds although others such as molybdenum can be used. Metal depositions similar to the above can also be accomplished by laser beam exposure and the described method herein may also be applicable. When these compounds are used to make long design patches the sheet resistance can be high enough to render the circuit inoperative. This limits the ability to make design changes. The process described in the following text will significantly reduce the sheet resistance of these metal film depositions and effectively extend these limits.

Figure 1

Typical FIB patch-SEM/schematic

SOLUTIONS

  The process described herein consists of sev- eral procedures related to specimen preparation in order to achieve a reduced sheet resistance of a metal vapor deposition compound used to modify semi- conductor circuits, The structure formed by the proc- ess described below is referred to as a "design patch? The process sequence is described in the following

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Technical Developments Volume 22 June 1994

1. Contact windows are milled via FIB (Focused Ion Beam) or Excimer Laser Ablation.

2. A coating approximately I& thick of a highly conductive element or compound is deposited onto a passivated specimen. (A gold (Au-60Yo) and pal- ladium (Pd-400/o) compound was sputtered on the surface of an integrated circuit for the purpose of proving this process.)

3. The specimen is placed into the vacuum cham- ber of the FIB and circuit modifications are made by metal vapor depositing (MVD) a platinum@) compound, such as (Timethyl)methylcyclopenta- dienylplatinu m(IV) (CH3)3(CH3C5H4)Pt. The Au/Pd coating is now masked in the area(s) where the Pt modification(s) was made. It should be emphasized that there are other MVD or CVD (chemical vapor deposition) compounds (such as tungsten "W" or molybdenum "MO") that are used for FIB "Design Patches" and that the spe- cific compound or brand name is not essential to this process.

4. Steps "1" through "3" can...