Apparatus for filling apertures in a film layer on a semiconductor structure

Abstract

The present invention pertains to a carrier layer and a contact enabled by the carrier layer which enables the fabrication of aluminum (including aluminum alloys and other conductive materials having a similar melting point) electrical contacts in multilayer integrated circuit vias, through holes, or trenches having an aspect ratio greater than one. In fact, the structure has been shown to enable such contact fabrication in vias, through holes, and trenches having aspect ratios as high as at least 5:1, and should be capable of filing apertures having aspect ratios up to about 12:1. The carrier layer, in addition to permitting the formation of a conductive contact at high aspect ratio, provides a diffusion barrier which prevents the aluminum from migrating into surrounding substrate material which operates in conjunction with the electrical contact. The carrier layer preferably comprises a layer formed by ionizing the flux of sputter deposition material, partially reacting the flux with a gas, and depositing the resulting material on a substrate.

We claim:  
     
         1 . An electrical contact in a multilayer integrated circuit, wherein the aspect ratio of the aperture within which the electrical contact is formed exceeds 1:1, said electrical contact comprising: 
 an aperture lining composed of a carrier layer; and    a sputtered conductor deposited over said carrier layer and reflowed to fill said aperture.    
     
     
         2 . The contact of  claim 1 , wherein said carrier layer is deposited in a sputtering chamber, and at least a portion of the material sputtered from the target to form the carrier layer is ionized prior to the deposition thereof on the substrate.  
     
     
         3 . The contact layer of  claim 2 , wherein said carrier layer also includes, in part, a component of the target material reacted with a second species before being deposited on the substrate.  
     
     
         4 . The contact of  claim 1 , wherein said carrier layer includes a first sub-layer of a material sputtered from a target and deposited on the substrate after a portion thereof has been ionized, a second sub-layer of sputtered material deposited on said first layer after a portion of the sputtered material is ionized and is further reacted with a gas before being deposited, and a third sub-layer applied over the surface of said second sub-layer, said third layer forming a surface layer comprised of a first portion of sputtered material which has been ionized before it is deposited on the second sub-layer and a portion which has been ionized and reacted with a gas before being deposited on the substrate.  
     
     
         5 . The contact of  claim 1 , wherein said carrier layer includes at least two sub-layers, and the outermost surface layer of said sub-layers is formed of sputtered material which has been ionized prior to deposition thereof on the substrate.  
     
     
         6 . The contact of claims  4  or  5 , wherein said surface layer contains reactive ion-deposition sputtered refractory metal compound which has been ionized and reacted with a gas at concentrations of less than about 10% by weight of said surface layer.  
     
     
         7 . The contact of  claim 6 , wherein said sputtered material is titanium.  
     
     
         8 . The contact of  claim 7 , wherein said gas is nitrogen.  
     
     
         9 . The contact of  claim 1 , wherein said carrier layer provides a barrier layer.  
     
     
         10 . The contact of  claim 1 , wherein said carrier layer is a wetting layer.  
     
     
         11 . The contact of  claim 1 , wherein said carrier layer has an rms surface roughness of less than 40 Angstroms.  
     
     
         12 . The contact of  claim 1 , wherein said carrier layer is comprised of densely packed grains oriented to minimize the resistance of conductors flowed thereover.  
     
     
         13 . The contact of  claims 1  to  12 , wherein said conductor is aluminum.  
     
     
         14 . A carrier layer which enables the fabrication of an electrical contact in a multilayer integrated circuit, wherein the aspect ratio of the electrical contact exceeds 1:1, said structure comprising at least one layer of a sputtered material, a first component of which has been ionized, at least in part, prior to deposition thereof on the substrate and a second component of which has been ionized, and reacted with a gas, prior to the deposition thereof on the substrate.  
     
     
         15 . The carrier layer of  claim 14 , wherein said sputtered material is titanium and said gas is nitrogen.  
     
     
         16 . The carrier layer of  claim 14 , wherein the carrier layer provides a barrier layer.  
     
     
         17 . An electrical contact in a multilayered integrated circuit, wherein the aspect ratio of said electrical contact exceeds 1:1, said electrical contact comprising: 
 a) at least one first layer formed of a sputtered refractory metal compound which has been ionized at least in part before deposition on the substrate and which has been reacted in part with a gas prior to the deposition thereof onto the substrate, said first layer applied over the surface of an opening through which said electrical contact is to pass; and    b) at least one layer of conductive material applied over the surface of said first layer and reflowed to fill said contact.    
     
     
         18 . The electrical contact of  claim 17  wherein said layer of conductive material is deposited by sputtering.  
     
     
         19 . An electrical contact in a multilayered integrated circuit, wherein the aspect ratio of said electrical contact exceeds 1:1, said electrical contact comprising: 
 a) at least one first layer of a sputtered refractory metal formed on said substrate after at least a portion thereof has been ionized, said first layer applied over the surface of an opening through which said electrical contact is to pass;    b) at least one second layer formed of a sputtered refractory metal compound which has been ionized at least in part before deposition on the second layer and which has been reacted with a gas prior to the deposition thereof onto the second layer;    c) at least one third layer formed of a sputtered refractory metal which has been ionized at least in part before deposition on the substrate and which has been reacted in part with a gas prior to the deposition thereof onto the substrate, said first layer applied over the surface of an opening through which said electrical contact is to pass; and    d) at least one layer of conductive material applied over the surface of said second layer and reflowed to fill said contact.    
     
     
         20 . The electrical contact of  claim 19 , wherein said refractory metal compound is titanium nitride, said refractory metal is titanium, and said conductive material is aluminum or an aluminum alloy.  
     
     
         21 . The electrical contact of  claim 19 , wherein said aluminum or aluminum alloy is deposited by sputtering.  
     
     
         22 . A method of producing a barrier layer which enables the fabrication of a sputtered electrical contact in a multilayer integrated circuit, wherein the aspect ratio of the electrical contact exceeds 1:1, said method including the step of providing a carrier layer composed of a combination of the target material and a compound of the target material and a gas.  
     
     
         23 . The method of  claim 22 , wherein the target material is a refractory metal.  
     
     
         24 . The method of  claim 23 , wherein said refractory metal is titanium and the gas is nitrogen.  
     
     
         25 . The method of  claim 24 , wherein said carrier layer is formed by gradually eliminating the presence of reactive nitrogen gas from the chamber in which said carrier layer is being formed.  
     
     
         26 . The method of  claim 25 , wherein said presence of nitrogen gas is eliminated by gradually discontinuing the flow of nitrogen gas to the chamber in which said second layer is being formed.  
     
     
         27 . The method of  claim 25 , wherein the power to said ion-deposition sputtering process is turned off at a specific time during said eliminating of said nitrogen gas presence from the chamber, or is turned off a specific time period after elimination of said presence of said reactive nitrogen gas.  
     
     
         28 . A method of forming an electrical contact in a multilayered integrated circuit, wherein the aspect ratio of said electrical contact exceeds 1:1, said method comprising the steps of: 
 a) depositing from a source of ionized material at least one layer of a refractory metal comprised of at least a portion of refractory metal and a portion of refractory metal compound formed by reacting the ionized refractory metal with a gas, over the surface of an opening through which said electrical contact is to pass; and    b) depositing from a source of sputtered material at least one layer of conductive material over the surface of the refractory metal layer until the through hole is filled with the conductive material;    c) the step of said filling the opening with conductive material includes the steps of depositing the conductive material to form a seed layer, and then continuing to deposit the conductive material layer while maintaining the substrate at a reflow temperature.    
     
     
         29 . The method of  claim 28 , wherein the reflow step is achieved at a substrate temperature of no more than 360 C. in no more than 4 minutes, and the conductor is aluminum.  
     
     
         30 . The method of  claim 28 , wherein the reflow step is achieved at a substrate temperature of no more than 420 C. in no more than 2 minutes and the conductor is aluminum.  
     
     
         31 . The method of  claim 28 , wherein the reflow step is accomplished at 350 C. in no more than 10 minutes and the conductor is aluminum.  
     
     
         32 . The method of  claims 29  to  31 , wherein the contact has an aspect ration of 5:1.  
     
     
         33 . An apparatus for filling apertures in a film layer on a semiconductor substrate, comprising: 
 an sputter chamber for providing an ionized deposition material to form a conformal film layer over the wall and base of the aperture, said chamber including a deposition material source, a gas supply, a substrate positioning member for positioning a substrate in said chamber, and an ionizing member for ionizing at least a portion of the deposition material before it is deposited on the substrate;    a deposition chamber for providing a source of deposition material for deposition over the film formed in the aperture in said sputter chamber; and    a transfer chamber interconnecting said sputter chamber and said deposition chamber.    
     
     
         34 . The apparatus of  claim 33 , wherein: 
 said sputter chamber includes a reactive gas inlet for selectively introducing a gas into said chamber to react with at least a portion of said deposition material prior to the deposition of said ionized particles on the substrate.    
     
     
         35 . The apparatus of  claim 34 , wherein said sputter chamber further includes a sputtering target composed of a deposition material.  
     
     
         36 . The apparatus of  claim 35 , wherein said deposition chamber includes at least a target, a gas inlet, and a power supply for supplying energy to convert the gas supplied by said gas supply into a plasma and thereby sputter the target to provide the deposition material.  
     
     
         37 . The apparatus of  claim 36 , wherein said deposition chamber further includes a valve for at least opening and closing said reactive gas supply, and a system controller coupled to said valve to selectively open and close said valve during the sputtering of said target.  
     
     
         38 . The apparatus of  claim 37 , wherein said valve is maintainable in a closed position, then an open position and then again in a closed position as said target is sputtered.  
     
     
         39 . The apparatus of  claim 38 , wherein said target in said sputter chamber is a refractory metal.  
     
     
         40 . The apparatus of  claim 39 , wherein said target in said sputtering chamber includes titanium.  
     
     
         41 . The apparatus of claim  40 , wherein said reactive gas is nitrogen.  
     
     
         42 . The apparatus of claim  41 , wherein said ionizing member includes at least one turn of a conductor extending about a plasma formation region in the ion-deposition chamber.