Process for lowering adhesion layer thickness and improving damage resistance for thin ultra low-k dielectric film

Abstract

An improved method for depositing an ultra low dielectric constant film stack is provided. Embodiments of the invention minimize k (dielectric constant) impact from initial stages of depositing the ultra low dielectric constant film stack by reducing a thickness of an oxide adhesion layer in the ultra low dielectric film stack (<2 kÅ) to about or less than 200 Å, thereby lowering the thickness non-uniformity of the film stack to less than 2%. The improved process deposits the oxide adhesion layer and the bulk layer in the ultra low dielectric film stack at lower deposition rate and lower plasma density in combination with higher total flow rate, resulting in better packing/ordering of the co-deposited species during film deposition which causes higher mechanical strength and lower porosity. The improved adhesion layer provides high adhesion energy for better adhesion with ultra low dielectric constant films to underlying barrier/liner layers. The resulting low dielectric film has nanometer-sized pores and tighter pore-size distribution, yielding a low dielectric constant film with a dielectric constant of about 2.5 or less.

1 . A method of processing a substrate disposed within a processing chamber, comprising:
 flowing into the processing chamber a gas mixture comprising a flow rate of one or more organosilicon compounds and a flow rate of one or more porogen compounds to deposit an initiation layer on the substrate by applying a radio frequency (RF) power to the processing chamber;   ramping-up the flow rate of the one or more organosilicon compounds until reaching a final flow rate of the one or more organosilicon compounds to deposit a first transition layer on the initiation layer; and   while flowing the final flow rate of the one or more organosilicon compounds, ramping-up the flow rate of the one or more porogen compounds until reaching a final flow rate of the one or more porogen compounds to deposit a second transition layer on the first transition layer, wherein the depositions of the initiation layer and the first and second transition layers are performed at a ratio of the RF power to a total flow rate between about 0.1 W/sccm and about 0.3 W/sccm.   
     
     
         2 . The method of  claim 1 , wherein the deposition of the initiation layer is performed over a time period in the range of between about 0.5 second and about 5 seconds. 
     
     
         3 . The method of  claim 1 , wherein the deposition of the first and second transition layers is performed over a time period in the range of between about 1 second and about 5 seconds and between about 1 second and about 10 seconds, respectively. 
     
     
         4 . The method of  claim 1 , wherein the one or more organosilicon compound are introduced into the chamber at a flow rate between about 200 mgm and about 700 mgm and the one or more porogen compounds are introduced into the chamber at a flow rate between about 200 mgm and about 1600 mgm. 
     
     
         5 . The method of  claim 1 , wherein the depositions of the initiation layer and the first and second transition layers are performed at a deposition rate between 1000 Å/min. and about 3500 Å/min and at a low RF power between about 350 W and about 500 W. 
     
     
         6 . The method of  claim 5 , wherein the initiation layer and the first and second transition layers are deposited to provide an overall thickness in a range of about 50 Å to about 300 Å. 
     
     
         7 . The method of  claim 1 , wherein the ramping-up the flow rate of the one or more organosilicon compounds is performed at a ramp-up rate between about 600 mgm/sec. and about 1500 mgm/sec. 
     
     
         8 . The method of  claim 1 , wherein the ramping-up the flow rate of the one or more porogen compounds is performed at a ramp-up rate between about 200 mgm/sec. and about 600 mgm/sec. 
     
     
         9 . The method of  claim 1 , wherein the gas mixture further comprises one or more oxidizing gases selected from the group consisting of ozone, oxygen, carbon dioxide, carbon monoxide, water, nitrous oxide, 2,3-butanedione, and combinations thereof. 
     
     
         10 . The method of  claim 1 , further comprising introducing into the processing chamber a flow rate of an inert gas selected from the group consisting of helium, argon, or nitrogen. 
     
     
         11 . The method of  claim 1 , wherein the one or more organosilicon compounds is selected from the group consisting of methyldiethoxysilane (mDEOS), tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetrasiloxane (OMCTS), trimethylsilane (TMS), pentamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, dimethyldisiloxane, tetrasilano-2,6-dioxy-4,8-dimethylene, tetramethyldisiloxane, hexamethyldisiloxane (HMDS), 1,3-bis(silanomethylene)disiloxane, bis(1-methyldisiloxanyl)methane, bis(1-methyldisiloxanyl)propane, hexamethoxydisiloxane (HMDOS), dimethyldimethoxysilane (DMDMOS), dimethoxymethylvinylsilane (DMMVS), and derivatives thereof. 
     
     
         12 . The method of  claim 1 , wherein the one or more porogen compounds is selected from the group consisting of norbornadiene (BCHD, bicycle(2.2.1)hepta-2,5-diene), 1-methyl-4-(1-methylethyl)-1,3-cyclohexadiene (ATP or alpha-Terpinene), vinylcyclohexane (VCH), phenylacetate, butadiene, isoprene, cyclohexadiene, bicycloheptadiene, 1-methyl-4-(1-methylethyl)-benzene (Cymene), 3-carene, fenchone, limonene, cyclopentene oxide, vinyl-1,4-dioxinyl ether, vinyl furyl ether, vinyl-1,4-dioxin, vinyl furan, methyl furoate, furyl formate, furyl acetate, furaldehyde, difuryl ketone, difuryl ether, difurfuryl ether, furan, 1,4-dioxin, and fluorinated carbon derivatives thereof. 
     
     
         13 . A method of processing a substrate disposed within a processing chamber, comprising:
 providing a substrate bearing a liner/barrier layer;   depositing a carbon-containing oxide adhesion layer over the liner/barrier layer at a deposition rate between about 1000 Å/min and about 3500 Å/min, comprising:
 flowing into the processing chamber a gas mixture comprising a flow rate of one or more organosilicon compounds and a flow rate of one or more porogen compounds to deposit an initiation layer on the substrate by applying a radio frequency (RF) power level of about 300 W to about 600 W at 13.56 MHz to the processing chamber; 
 ramping-up the flow rate of the one or more organosilicon compounds until reaching a final flow rate of the one or more organosilicon compounds to deposit a first transition layer on the initiation layer; and 
 while flowing the final flow rate of the one or more organosilicon compounds, ramping-up the flow rate of the one or more porogen compounds until reaching a final flow rate of the one or more porogen compounds to deposit a second transition layer on the first transition layer; 
 depositing a low K film over the adhesion layer; and 
 curing the deposited low K film to form nanopores therein. 
   
     
     
         14 . The method of  claim 13 , wherein the deposition of the initiation layer is performed over a time period in the range of between about 0.5 second and about 5 seconds. 
     
     
         15 . The method of  claim 13 , wherein the deposition of the first transition layer is performed over a time period in the range of between about 1 second and about 5 seconds, and the deposition of the second transition layer is performed over a time period in the range of and between about 1 second and about 10 seconds. 
     
     
         16 . The method of  claim 13 , wherein the one or more organosilicon compounds are introduced into the chamber at a flow rate between about 200 mgm and about 700 mgm and the one or more porogen compounds are introduced into the chamber at a flow rate between about 200 mgm and about 1600 mgm. 
     
     
         17 . The method of  claim 13 , wherein the initiation layer and the first and second transition layers are deposited to provide an overall thickness in a range of about 50 Å to about 300 Å. 
     
     
         18 . The method of  claim 13 , wherein the ramping-up the flow rate of the one or more organosilicon compounds is performed at a ramp-up rate between about 600 mgm/sec. and about 1500 mgm/sec, and the ramping-up the flow rate of the one or more porogen compounds is performed at a ramp-up rate between about 200 mgm/sec. and about 600 mgm/sec. 
     
     
         19 . The method of  claim 13 , wherein the depositions of the initiation layer and the first and second transition layers are performed at a ratio of the RF power to a total flow rate between about 0.1 W/sccm and about 0.3 W/sccm. 
     
     
         20 . The method of  claim 13 , wherein the gas mixture further comprises an inert gas selected from the group consisting of helium, argon, and nitrogen, and one or more oxidizing gases selected from the group consisting of ozone, oxygen, carbon dioxide, carbon monoxide, water, nitrous oxide, 2,3-butanedione, and combinations thereof. 
     
     
         21 . The method of  claim 13 , wherein the one or more organosilicon compounds is selected from the group consisting of methyldiethoxysilane (mDEOS), tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetrasiloxane (OMCTS), trimethylsilane (TMS), pentamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, dimethyldisiloxane, tetrasilano-2,6-dioxy-4,8-dimethylene, tetramethyldisiloxane, hexamethyldisiloxane (HMDS), 1,3-bis(silanomethylene)disiloxane, bis(1-methyldisiloxanyl)methane, bis(1-methyldisiloxanyl)propane, hexamethoxydisiloxane (HMDOS), dimethyldimethoxysilane (DMDMOS), dimethoxymethylvinylsilane (DMMVS), and derivatives thereof. 
     
     
         22 . The method of  claim 13 , wherein the one or more porogen compounds is selected from the group consisting of norbornadiene (BCHD, bicycle(2.2.1)hepta-2,5-diene), 1-methyl-4-(1-methylethyl)-1,3-cyclohexadiene (ATP or alpha-Terpinene), vinylcyclohexane (VCH), phenylacetate, butadiene, isoprene, cyclohexadiene, bicycloheptadiene, 1-methyl-4-(1-methylethyl)-benzene (Cymene), 3-carene, fenchone, limonene, cyclopentene oxide, vinyl-1,4-dioxinyl ether, vinyl furyl ether, vinyl-1,4-dioxin, vinyl furan, methyl furoate, furyl formate, furyl acetate, furaldehyde, difuryl ketone, difuryl ether, difurfuryl ether, furan, 1,4-dioxin, and fluorinated carbon derivatives thereof.