Metallization to improve electromigration resistance by etching concavo-concave opening

• US 5,633,197 A
• Filed: 09/29/1995
• Issued: 05/27/1997
• Est. Priority Date: 05/11/1994
• Status: Expired due to Term

• Current Assignee: United Microelectronics Corporation
• Original Assignee: United Microelectronics Corporation
• Inventors: Lur, Water, Wu, Jiun Y.
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): BILODEAU, THOMA
• Application Number:
  US08/536,858
• Time in Patent Office: 606 Days
• Field of Search: 437/957, 437/195, 437/187, 437/947, 437/981, 437/978, 437/228, 148/DIG. 42, 257/774
• US Class Current: 438/668
• CPC Class Codes: H01L 21/76804 by forming tapered via holes
• CPC Class Codes: H01L 23/485 consisting of layered constructions comprising conductive layers and insulating layers, e.g. planar contacts H01L23/4821, H01L23/4822, H01L23/4824, H01L23/4825 take precedence; materials H01L23/532, bond pads H01L24/02, bump connectors H01L24/10
• CPC Class Codes: H01L 23/5226 Via connections in a multilevel interconnection structure
• CPC Class Codes: H01L 23/528 Geometry or layout of the interconnection structure H01L27/0207 takes precedence; algorithms G06F30/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10S 148/161 Tapered edges
• CPC Class Codes: Y10S 438/927 Electromigration resistant metallization
• CPC Class Codes: Y10S 438/978 forming tapered edges on substrate or adjacent layers

Abstract

A new method of metallization using a new design of metal contact shape, contact/via profile, and metal lines having considerably reduced current density and improved electromigration of metal lines is achieved. Metal contacts are formed in a rectangular shape instead of a square shape with the wider side perpendicular to the current direction. Contact openings are made having concavo-concave profiles which can provide a wider conducting cross-sectional area than can conventional openings with a vertical profile near the contact bottom. Gaps are formed within wide and high current metal lines so that current density can be effectively lowered by utilizing the whole metal line uniformly.

Claims

1. A method of forming contact openings having concavo-concave profiles in the fabrication of an integrated circuit, the method comprising:

providing a first undoped layer of tetraethoxysilane (TEOS) oxide over the surface of a semiconductor substrate;

depositing a doped layer of TEOS oxide over said first undoped TEOS oxide layer;

depositing a second undoped layer of TEOS oxide over said doped TEOS oxide layer;

anisotropically etching through said three TEOS oxide layers to provide a contact opening with vertical sidewalls;

wet etching said three TEOS oxide layers wherein said first and second undoped TEOS oxide layers etch faster than said doped TEOS oxide layer. wherein each said vertical sidewall is transformed into a concave shape and wherein said contact opening will have a concavo-concave shape; and

filling said contact openings with conductive material.

2. The method of claim 1 wherein said doped TEOS oxide layer is doped with boron and phosphorus.

3. The method of claim 1 wherein said anisotropically etching through said three TEOS oxide layers is a dry etch.