Local multilayered metallization

• US 20050074966A1
• Filed: 08/31/2004
• Published: 04/07/2005
• Est. Priority Date: 09/02/1999
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Rhodes, Howard E.
• Granted Patent: US 7,375,026 B2
• Time in Patent Office: Days
• US Class Current: 438/629
• CPC Class Codes: H01L 21/76816 Aspects relating to the layout of the pattern or to the size of vias or trenches layout of the interconnections per se H01L23/528; CAD of ICs G06F30/00
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 2224/02126 Collar structures
• CPC Class Codes: H01L 2224/02166 Collar structures
• CPC Class Codes: H01L 2224/023 Redistribution layers [RDL] for bonding areas
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05006 Dual damascene structure
• CPC Class Codes: H01L 2224/05073 Single internal layer
• CPC Class Codes: H01L 2224/05147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05166 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05181 Tantalum [Ta] as principal constituent
• CPC Class Codes: H01L 2224/05187 Ceramics, e.g. crystalline carbides, nitrides or oxides glass ceramics H01L2224/05188
• CPC Class Codes: H01L 2224/05546 Dual damascene structure
• CPC Class Codes: H01L 2224/05552 in top view
• CPC Class Codes: H01L 2224/05567 the external layer being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48724 : Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 23/5283 : Cross-sectional geometry
• CPC Class Codes: H01L 23/53238 : Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 24/03 : Manufacturing methods
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/06 : of a plurality of bonding areas
• 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 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 2924/0001 : Technical content checked by a classifier
• 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 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01031 : Gallium [Ga]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/04941 : TiN
• CPC Class Codes: H01L 2924/04953 : TaN
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/30105 : Capacitance

Abstract

An interconnect comprises a trench and a number of metal layers above the trench. The trench has a depth and a width. The depth is greater than a critical depth, and the number of metal layers is a function of the width. In an alternate embodiment, a metallization structure having a trench including a metal layer and a second trench including a plurality of metal layers coupled to the metal layer is disclosed. The metal layer is highly conductive, and at least one of the plurality of metal layers is a metal layer that is capable of being reliably wire-bonded to a gold wire. The trench is narrower than the second trench, and at least one of the plurality of metal layers is copper or a copper alloy.

Claims

1. A method for forming an interconnect comprising:

selecting an insulative surface;

selecting a number of metallization stack layers having a critical thickness;

etching a trench on the insulative surface, the trench having a depth greater than the critical thickness and a width less than a sidewall thickness of a first metallization stack, and the trench coupling a first memory cell to a second memory cell;

etching a second trench on the insulative surface, the second trench having a depth greater than the critical thickness and a width greater than the sidewall thickness and less than a second sidewall thickness of a second metallization stack;

depositing the first metal layer;

depositing the second metal layer; and

planarizing the insulative surface.

2. The method of claim 1, wherein depositing a first metal comprises depositing copper.

3. The method of claim 1, wherein planarizing the insulative surface comprises planarizing by chemical mechanical polishing.

4. A method for dimensioning a trench comprising:

selecting a number of layers, the number of layers having a sidewall thickness;

selecting a second number of layers having a second sidewall thickness, wherein the second number of layers has one less metal layer than the number of layers;

identifying a critical depth; and

dimensioning the trench to have a depth greater than the critical depth and a width less than the sidewall thickness but greater than the second sidewall thickness.

5. The method of claim 4, wherein identifying a critical depth comprises:

calculating a total bottom thickness for one less layer than the number of layers, the total bottom thickness being the critical depth.

6. A method of forming a conductive structure comprising:

etching a trench having a depth greater than a critical depth in a substrate having a surface;

under filling the trench with a first conductive material;

overfilling the trench with a second conductive material suitable for high reliability wire-bonding; and

polishing the substrate until the first conductive material and the second conductive material are removed from the surface of the substrate.

7. The method of claim 6, wherein polishing the substrate until the first conductive material and the second conductive material are removed from the surface of the substrate comprises:

applying chemical mechanical polishing to remove the first conductive material and the second conductive material from the surface of the substrate.

8. A method of forming a conductive structure comprising:

etching a fine line trench to a depth greater than a critical depth in a substrate having a surface;

etching a wide line trench to the depth in the substrate such that the wide line trench intersects the fine line trench;

filling the fine line trench with a first conductive material;

under filling the wide line trench with the first conductive material;

filling the wide line trench with a second conductive material suitable for high reliability wire-bonding; and

polishing the substrate until the first conductive material and the second conductive material are removed from the surface of the substrate.

9. The method of claim 8, wherein filling the fine line trench with a first conductive material comprises:

overfilling the fine line trench with a first conductive material.

10. The method of claim 8, wherein filling the wide line trench with a second conductive material suitable for high reliability wire-bonding comprises:

under filling the wide line trench with a second conductive material suitable for high reliability wire-bonding.

11. A method of forming a conductive structure comprising:

etching a wide line trench having a depth greater than a critical depth in the substrate;

depositing a seed layer above the surface of the substrate;

depositing a layer of conductive material above the seed layer such that the conductive material under fills the wide line trench;

depositing a barrier layer above the layer of conductive material;

depositing a second layer of conductive material above the barrier layer, the second layer of conductive material is capable of reliably wire bonding to a gold wire; and

removing the seed layer, the layer of conductive material, the barrier layer, and the second layer of conductive material from the surface of the substrate.

12. The method of claim 11, wherein depositing a layer of conductive material above the seed layer such that the conductive material under fills the wide line trench comprises:

electroplating a layer of copper above the seed layer such that the copper under fills the wide line trench.

13. The method of claim 11, wherein depositing a second layer of conductive material above the barrier layer, the second layer of conductive material is capable of reliably wire bonding to a gold wire comprises:

depositing a layer of aluminum above the barrier layer, the aluminum layer is capable of reliably wire bonding to a gold wire.

14. A computer system comprising:

a processor;

a device coupled to the processor; and

a interconnect coupled to the device, the interconnect comprising;

a trench having a depth greater than a critical depth and a metal layer; and

a bond pad trench having a bond pad depth equal to the depth and a plurality of metal layers coupled to the metal layer.

15. The computer system of claim 14, further comprising:

a conductive wire eutectically bonded to at least one of the plurality of metal layers.

16. A computer system comprising:

a processor;

a device coupled to the processor; and

a connective structure coupled to the device, the connective structure comprising;

a trench having a depth greater than a critical depth, a barrier layer, and a copper layer above the barrier layer;

a bond pad trench having a barrier layer, the bond pad trench having a copper layer above the barrier layer, and the bond pad trench having a titanium layer above the copper layer, and an aluminum-copper layer above the titanium layer.

17. A computer system comprising:

a processor;

a device coupled to the processor; and

an interconnect coupled to the device, the interconnect comprising;

a fine line having a conductive layer; and

a wide line having a number of conductive layers, and at least one of the number of conductive layers of the wide line being coupled to the fine line.

18. The computer system of claim 17, wherein the wide line is capable of being reliably wire bonded to a conductive gold wire.

19. A computer system comprising:

a processor;

a device coupled to the processor; and

an interconnect coupled to the device, the interconnect comprising;

a fine line having a depth greater than a critical depth, a barrier layer and a layer of electroplated copper; and

a wide line having a wide line depth equal to the depth, a number of conductive layers, and at least one of the number of conductive layers coupled to the electroplated copper.

20. The computer system of claim 19, wherein at least one of the number of conductive layers is wire-bonded to a gold wire.

21. The computer system of claim 19, wherein a eutectic bond is used to wire-bond at least one of the number of conductive layers to a gold wire.

22. A computer system comprising:

a processor;

a device coupled to the processor; and

a conductive structure coupled to the device, the conductive structure comprising;

a fine line having a layer of electroplated copper; and

a wide line having a number of conductive layers, at least one of the number of conductive layers is capable of eutectic bonding to a gold wire, and the wide line is coupled to the fine line.

23. A computer system comprising:

a processor;

a device coupled to the processor; and

a connective structure coupled to the device, the connective structure comprising;

a fine line having a single layer of electroplated copper having a depth greater than a critical depth; and

a wide line having a stack of conductive layers capable of eutectic bonding to a gold wire, and the wide line coupled to the fine line and the wide line having a depth greater than a critical depth.

24. A computer system comprising:

a processor;

a device coupled to the processor; and

a conductive structure coupled to the device, the conductive structure comprising;

a fine line having a depth greater than a critical depth and a single layer of electroplated copper; and

a wide line having a wide line depth equal to the depth, and a stack comprising a barrier layer, a copper layer, and an aluminum layer capable of eutectic bonding to a conductive material, and the wide line coupled to the fine line.

25. The computer system of claim 24, wherein the barrier layer comprises a refractory metal/refractory metal nitride.