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Browse Prior Art Database

Damascene Electromigration Resistant Stud Contact

IP.com Disclosure Number: IPCOM000119915D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+3]

Abstract

Refractory metal, e.g., tungsten (W), is selectively deposited on exposed surfaces of W studs before metal having a relatively low melting point, e.g., aluminum (Al) or aluminum/copper (AlCu), is deposited to form conductive lines. Regions of high current density due to stud and line misalignment are comprised of electromigration resistant W. Thus, reliability of contacts between lines and studs is improved significantly, especially as size of lines and studs is decreased and/or alignment becomes relatively poor.

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Damascene Electromigration Resistant Stud Contact

      Refractory metal, e.g., tungsten (W), is selectively
deposited on exposed surfaces of W studs before metal having a
relatively low melting point, e.g., aluminum (Al) or aluminum/copper
(AlCu), is deposited to form conductive lines.  Regions of high
current density due to stud and line misalignment are comprised of
electromigration resistant W. Thus, reliability of contacts between
lines and studs is improved significantly, especially as size of
lines and studs is decreased and/or alignment becomes relatively
poor.

      Referring to Fig. 1, top view, and Fig. 2, cross-section B-B, W
stud 10 is first formed through insulating layer 12 and made to be
coplanar with the surface of layer 12 by conventional processing.
Insulating layer 14 is deposited and line-defining trench 16 is made
by photo-masking and etching in a standard manner.  As shown, there
is misalignment between an early mask used to define position of stud
10 and the mask used to define position of trench 16.  In this new
process, selective W 18 is deposited next.  Al is then deposited and
planarized as usual to form a conductive line in trench 16.

      Due to misalignment, high current density is caused in the stud
10 and line 16 current path at overlap area A.  The conductor in the
vicinity of A is now comprised entirely of highly electromigration
resistant refractory metal.  The area of contact between W and Al,
which is sometimes an i...