Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1998-11-27
2001-03-27
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S627000, C438S643000, C438S648000, C438S653000, C438S656000, C438S685000
Reexamination Certificate
active
06207568
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods for forming conductor layers within microelectronics fabrications. More particularly, the present invention relates to methods for forming electromigration resistant aluminum containing conductor layers within microelectronics fabrications.
2. Description of the Related Art
Microelectronics fabrications are formed from microelectronics substrates over which are formed patterned microelectronics conductor layers which are separated by microelectronics dielectric layers.
As microelectronics fabrication integration levels have increased, and patterned microelectronics fabrication conductor layer dimensions have decreased, it has become common for microelectronics fabrications which employ patterned aluminum containing microelectronics conductor layers to experience electromigration effects when the patterned aluminum containing microelectronics conductor layers are employed for carrying comparatively high electrical current densities of greater than about 2E5 amps per square centimeter. Electromigration effects are undesirable within advanced microelectronics fabrications since electromigration effects provide microelectronics fabrications with compromised functionality or reliability.
It is thus towards the goal of forming within advanced microelectronics fabrications patterned aluminum containing microelectronics conductor layers with enhanced electromigration resistance that the present invention is directed.
Various methods have been disclosed in the art of microelectronics fabrication for forming within microelectronics fabrications aluminum containing conductor layers, as well as other types of conductor layers, within desirable properties within microelectronics fabrications.
For example, Nulman et al., in U.S. Pat. No. 5,242,860, discloses a method for forming upon a silicon substrate employed within an integrated circuit microelectronics fabrication a titanium nitride layer with a (111) crystallographic orientation such that there may be formed upon the (111) titanium nitride layer a (111) aluminum containing conductor layer with inherently enhanced electromigration resistance. The method employs a titanium nitride layer of indeterminate crystallographic orientation formed interposed between a pair of titanium layers formed upon the silicon substrate to form a tri-layer stack, such that upon a thermal annealing of the tri-layer stack within a nitrogen containing atmosphere absent oxygen there is formed from the upper lying titanium layer a titanium nitride layer at least the surface of which has the (111) crystallographic orientation.
In addition, Yokoyama et al., in U.S. Pat. No. 5,312,772, discloses a method for forming within a semiconductor integrated circuit microelectronics fabrication, with improved bondability, step coverage, reliability and attenuated spiking into a silicon semiconductor substrate an aluminum containing conductor layer contacting the silicon semiconductor substrate at the location of a via through a dielectric layer, which via accesses the silicon semiconductor substrate. The method employs a bilayer underlayer upon which is formed the aluminum containing conductor layer, where the bilayer underlayer comprises a metal silicide forming metal layer having a metal nitride layer formed thereupon, the bilayer underlayer being formed upon both the dielectric layer and the silicon semiconductor substrate at the location of the via, where upon thermal annealing in a nitrogen atmosphere with a trace impurity of oxygen the bilayer underlayer the metal silicide forming metal layer forms a metal silicide layer at the location of the silicon substrate, but not at the location of the dielectric layer, and the metal nitride is oxidized to form a metal oxynitride surface layer.
Further, Maeda, in U.S. Pat. No. 5,449,641 and U.S. Pat. No. 5,581,125 discloses a method for forming an interconnect layer, and the interconnect layer formed employing the method, where the interconnect layer is formed of an aluminum containing conductor layer having a (111) crystallographic orientation. The method employs a titanium oxynitride barrier layer having a (111) crystallographic orientation, in conjunction with a high temperature sputtering of the aluminum containing conductor layer such that the (111) crystallographic orientation of the barrier layer is replicated within the aluminum containing conductor layer.
Still further, Wang, in U.S. Pat. No. 5,604,155, discloses a method for forming a silicon doped aluminum containing conductor contact layer with attenuated silicon nodule formation when forming the silicon doped aluminum containing conductor layer upon a barrier layer while employing a thermal sputtering method. The method employs a titanium adhesion promoter layer interposed between the silicon doped aluminum containing conductor layer and the barrier layer such that an aluminum titanate layer is formed which absorbs the silicon nodules which otherwise form when cooling the silicon doped aluminum containing conductor contact formed while employing the thermal sputtering method.
Finally, Foster et al., in U.S. Pat. No. 5,665,640, discloses a plasma enhanced chemical vapor deposition (PECVD) method for forming within a semiconductor integrated circuit microelectronics fabrication a titanium containing layer. The plasma enhanced chemical vapor deposition (PECVD) method employs a downstream flow of plasma induced radicals, such as formed employing a plasma activation of hydrogen, nitrogen or ammonia, admixed with a flow of a titanium tetrahalide in the vicinity of the substrate. The plasma enhanced chemical vapor deposition method may also employ a radio frequency biasing of a showerhead nozzle employed within an apparatus employed within the method.
Desirable within the art of microelectronics fabrication are additional methods and materials which may be employed for forming aluminum containing conductor layers with enhanced electromigration resistance within microelectronics fabrications.
It is towards that goal that the present invention is directed.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for forming an aluminum containing conductor layer within a microelectronics fabrication.
A second object of the present invention is to provide a method in accord with the first object of the present invention, where the aluminum containing conductor layer is formed with enhanced electromigration resistance.
A third object of the present invention is to provide a method in accord with the first object of the present invention or the second object of the present invention, which method is readily commercially implemented.
In accord with the objects of the present invention, there is provided a method for forming an aluminum containing conductor layer. To practice the method of the present invention, there is first provided a substrate. There is then formed over the substrate a titanium layer employing an ionized metal plasma bias sputtering method. There is then formed upon the titanium layer an aluminum containing conductor layer, wherein by employing the ionized metal plasma bias sputtering method for forming the titanium layer the aluminum containing conductor layer is formed with an enhanced (111) crystallographic orientation.
The present invention provides a method for forming an aluminum containing conductor layer within a microelectronics fabrication, where the aluminum containing conductor layer is formed with enhanced electromigration resistance. The method of the present invention realizes the foregoing objects by employing as an underlayer when forming the aluminum containing conductor layer a titanium layer formed employing an ionized metal plasma bias sputtering method to form the aluminum containing conductor layer with an enhanced (111) crystallographic orientation. The enhanced (111) crystallographic orientation provides enhanced electromigration resistance to the aluminum containing conductor layer.
The method of t
Liu Chung-Shi
Shue Shau-Lin
Yu Chen-Hua
Ackerman Stephen B.
Bowers Charles
Nguyen Thanh
Saile George O.
Stanton Stephen G.
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