Bonding pad structure to prevent inter-metal dielectric cracking and to improve bondability

• US 6,306,750 B1
• Filed: 01/18/2000
• Issued: 10/23/2001
• Est. Priority Date: 01/18/2000
• Status: Expired due to Term

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Huang, Yung-Sheng, Lu, Chun-Hung, Lin, Chiu-Ching, Hwang, Ruey-Lian
• Primary Examiner(s): Picardat, Kevin M.
• Assistant Examiner(s): COLLINS, DEVEN M
• Application Number:
  US09/483,934
• Time in Patent Office: 644 Days
• Field of Search: 438/612, 438/597, 438/611, 438/613
• US Class Current: 438/612
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05093 of a plurality of vias
• CPC Class Codes: H01L 2224/05556 in side view
• CPC Class Codes: H01L 2224/05558 conformal layer on a patterned surface
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/4807 of bonding interfaces, e.g. interlocking features
• CPC Class Codes: H01L 2224/48453 of the interface with the bonding area
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/48624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48647 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/78 Apparatus for connecting with wire connectors
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/85 using a wire connector wire bonding in general B23K20/004
• 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 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/14 : Integrated circuits

Abstract

A process of forming a bond pad structure, with a roughened top surface topography, used to improve the bondability of a gold wire bond, to the underlying bond pad structure, has been developed. The process features the use of a tungsten mesh pattern, formed in an IMD layer, and located underlying the bond pad structure, while overlying, and contacting, an underlying upper level, metal interconnect structure. The use of a tungsten mesh pattern, in place of individual tungsten studs, results in the creation of isolated islands, of IMED, reducing the bonding force, experienced by the IMD shapes, during the subsequent gold wire bond procedure. In addition the tungsten mesh pattern is formed via partial filling of a mesh pattern opening, in the IMD layer, resulting in an indented, or notched top surface. This in turn allows a roughened top surface, for the overlying bond pad structure, to be created, resulting in improved bondability of the gold wire, to the roughened top surface of the bond pad structure.

Claims

1. A method of creating a bond pad structure, on a semiconductor substrate, comprising the steps of:

providing an upper level, metal interconnect structure, overlying, and contacting, underlying conductive regions, on, or in, said semiconductor substrate;

forming an inter-metal dielectric, (IMD), layer, on said upper level, metal interconnect structure;

performing an etching procedure to create a mesh pattern opening, in said IMD layer, exposing regions of the top surface of said upper level, metal interconnect structure, and creating unetched, isolated islands of said IMD layer,

depositing a metal layer, on the top surface of said isolated islands of said IMD layer, and partially filling said mesh pattern opening;

removing portions of said metal layer from the top surface of said isolated islands of said IMD layer, creating a metal mesh structure, in said mesh pattern opening, with the metal mash structure featuring a notched, or indented top surface, resulting from the partial metal fill of said mesh pattern opening;

forming said bond pad structure, featuring a roughened top surface topography, as a result of the underlying notched, or indented surface, of said metal mesh structure; and

forming a wire bond on said bond pad structure.

2. The method of claim 1, wherein said upper level, metal interconnect structure is formed from a metal chosen from a group that includes;

aluminum—

copper, copper, or tungsten.

3. The method of claim 1, wherein said IMD layer is either a silicon oxide layer, or a borophosphosilicate glass layer, obtained via LPCVD or PECVD procedures, at a thickness between about 5000 to 15000 Angstroms.

4. The method of claim 1, wherein said mesh opening pattern is formed in said IMD layer via an anisotropic RIE procedure, using CHF₃ as an etchant.

5. The method of claim 1, wherein the width of said mesh pattern opening, or the space between said isolated islands of said IMD layer, is between about 0.3 to 1.5 um, while the dimensions of the top surface of said isolated islands of said IMD layer is 2.0 by 2.0 um.

6. The method of claim 1, wherein said metal layer is tungsten, obtained via LPCVD procedures, at a temperature between about 300 to 500°

C., to a thickness between about 3000 to 10000 Angstroms, using tungsten hexafluoride as a source.

7. The method of claim 1, wherein a chemical mechanical polishing procedure is used to form said metal mesh structure, in said mesh opening pattern.

8. The method of claim 1, wherein said bond pad structure, is formed from an aluminum—

copper layer, obtained via plasma vapor deposition procedures, at thickness between about 3000 to 12000 Angstroms, with a weight % of copper, between about 0 to 3%.

9. The method of claim 1, wherein said wire bond is a gold wire bond.

10. A method of forming a bond pad structure, on a tungsten mesh pattern, on a semiconductor substrate, with said tungsten mesh pattern comprised with an indented top surface topography, comprising the steps of

providing an upper level, metal interconnect structure, overlying, and contacting, conductive regions, on, or in, said semiconductor substrate,

forming an inter-metal dielectric, (IMD), layer, on said upper level, metal interconnect structure;

performing an anisotropic reactive ion etching procedure to pattern said IMD layer, creating an mesh pattern opening in said IMD layer, and creating isolated islands of said IMD layer, with regions of said upper level, metal interconnect structure, exposed in said mesh pattern opening;

depositing a tungsten layer, on the top surface isolated islands of said IMD layer, and partially filling said mesh pattern opening, resulting in said indented top surface topography for the portion of said tungsten layer residing in mesh pattern opening;

performing a chemical mechanical polishing procedure, to remove regions of said tungsten layer, from the top surface of said isolated islands of said IMD layer, and forming said tungsten mesh pattern, in said mesh pattern opening, with said tungsten mesh pattern featuring said indented top surface topography;

forming an aluminum-copper bond pad structure, with a roughened top surface topography, on said tungsten mesh pattern; and

forming a gold wire bond, on said aluminum-copper bond pad structure.

11. The method of claim 10, wherein said upper level, metal interconnect structure is comprised of a metal, chosen from a group that includes, aluminum—

copper, copper, or tungsten.

12. The method of claim 10, wherein said IMD layer is either a silicon oxide, or a borophosphosilicate glass layer, obtained via LPCVD or PECVD procedures, at a thickness between about 5000 to 15000 Angstroms.

13. The method of claim 10, wherein said mesh opening in said IMD layer, and said isolated islands of said IMD layer, are formed via the anisotropic RIE procedure, using CHF₃ as an etchant.

14. The method of claim 10, wherein the width of the opening, in said mesh pattern opening, or the space between said isolated islands of said IMD layer, is between about 0.3 to 1.5 um.

15. The method of claim 10, wherein the top surface dimension of said isolated islands of said IMD layer is between about 2.0 by 2.0 um.

16. The method of claim 10, wherein said tungsten layer, at a thickness between about 3000 to 10000 Angstroms, is obtained via LPCVD procedures, at a temperature between about 300 to 500°

C., using tungsten hexafluoride as a source.

17. The method of claim 10, wherein said aluminum—

copper bond pad structure, is formed from an aluminum—

copper layer, obtained via plasma vapor deposition procedures, at a thickness between about 3000 to 12000 Angstroms, comprised with a copper content, between about 0 to 3 weight percent.