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Method to Make Thin And Thick Lines Within a Single Level of Damascene Wiring Using a Single Photomask

IP.com Disclosure Number: IPCOM000102682D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR

Abstract

Thin, narrow tungsten (W) lines and thick, wide aluminum/copper (AL/Cu) lines result from formation of troughs in an insulator by use of a single photomasking process. Thus, low capacitance signal lines and larger cross-section, lower resistance lines are economically created on a single wiring level.

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Method to Make Thin And Thick Lines Within a Single Level of Damascene Wiring Using a Single Photomask

       Thin, narrow tungsten (W) lines and thick, wide
aluminum/copper (AL/Cu) lines result from formation of troughs in an
insulator by use of a single photomasking process.  Thus, low
capacitance signal lines and larger cross-section, lower resistance
lines are economically created on a single wiring level.

      Referring to Fig. 1, circuit patterns for lines in a single
level are first photoetched in insulator 10.  Lines to have low
capacitance to neighboring conductors are made to have width w = 2t,
where t is the thickness of a subsequent conformal W film.  Lines
required to have low electrical resistance but allowed to have higher
capacitance are made to have width in excess of 2t.  W is deposited
having thickness t and then isotropically etched to remove W until
narrow lines remain filled with W 12, rails of W 14 remain in corners
of wide lines, and all W is removed from the upper surface of
insulator 10.  Al/Cu 16 is then deposited and planarized, thereby
filling wide lines and completing the cross-section shown in Fig. 1.

      Referring to Fig. 2, W is selectively etched to leave thin,
narrow W lines and thick, wider Al/Cu lines.  Then an insulator 18
may be deposited and planarized to leave the cross-section shown in
Fig. 2.