Method for forming a contact plug with improved contact metal sealing
A method is provided for forming a metal contact plug. In one step, a substrate, which is an Si substrate or an SiO 2 substrate, is etched to form a contact hole. In one step, a dielectric liner layer is formed on a sidewall of the contact hole. In one step, the metal contact plug that is in contact with the dielectric liner layer is formed in the contact hole. In one step, an implantation process is performed on the substrate, so as to implant dopants having an atomic size greater than that of Si into the substrate.
1 . A method for forming a metal contact plug, comprising steps of:
etching a substrate to form a contact hole in the substrate, wherein the substrate is made of a material selected from a group consisting of Si and SiO 2 ;
forming a dielectric liner layer on a sidewall of the contact hole;
depositing a metal contact layer to fill the contact hole;
performing a planarization process to form a metal contact plug that is in contact with the dielectric liner layer in the contact hole, and to reveal the substrate that has a top surface where the metal contact plug is exposed; and
performing, after the planarization process, a first implantation process on the top surface of the substrate, wherein the first implantation process is one of a Ge implantation process, an Sn implantation process and a Pb implantation process.
2 . The method according to claim 1 , further comprising a step of performing a second implantation process on the substrate, wherein the second implantation process is one of a carbon implantation process and a fluorine implantation process, thereby implanting dopants of carbon or fluorine, which were previously absent from the substrate, into the substrate.
3 . The method according to claim 2 , wherein the second implantation process forms one of SiOC and SiOF in the substrate.
4 . The method according to claim 1 , further comprising, after the step of performing the first implantation process, a step of performing an annealing process for restoring damages resulting from the first implantation process.
5 . The method according to claim 1 , further comprising a step of performing a second implantation process on the top surface of the substrate where the metal contact plug is exposed, wherein the second implantation process is one of a carbon implantation process and a fluorine implantation process.
6 . The method according to claim 1 , further comprising, after the step of performing the first implantation process, a step of performing an annealing process for restoring damages resulting from the first implantation process.
7 . The method according to claim 6 , wherein the annealing process has a process temperature in a range from 400° C. to 500° C.
8 . The method according to claim 1 , wherein the substrate has a first surface and a second surface that are opposite to each other, and the first surface is above the second surface when viewed in a first direction, and
wherein the substrate is formed with a metal wire layer above the first surface of the substrate when viewed in the first direction, and the contact hole is formed in the second surface of the substrate.
9 . The method according to claim 1 , wherein a silicon-containing feature is exposed from the contact hole, and the method further comprises, after the dielectric liner layer is formed and before the metal contact layer is deposited, steps of:
conformally depositing a metal film on the substrate and in the contact hole, thereby forming a silicide layer at an interface between the silicon-containing feature and the metal film;
transforming the metal film into a metal nitride film by a plasma treatment that uses a gas including nitrogen; and
removing a portion of the metal nitride film that is outside of the contact hole and a portion of the metal nitride film that is disposed on the sidewall of the contact hole, thereby forming a metal nitride layer at a bottom of the contact hole and over the silicide layer.
10 . A method for forming a metal contact plug, comprising steps of:
forming a circuit component in a substrate that is made of a material selected from a group consisting of Si and SiO 2 ;
forming a metal wire layer above the circuit component when viewed in a first direction;
etching the substrate to form a contact hole that is above the circuit component when a second direction opposite to the first direction is considered an upward direction, the circuit component being exposed from a bottom of the contact hole when the second direction is considered the upward direction;
forming a dielectric liner layer on a sidewall of the contact hole;
forming the metal contact plug that is in contact with the dielectric liner layer in the contact hole;
performing, after the metal contact plug is formed, a first implantation process to implant a plurality of first dopants that have an atomic size greater than that of Si into a surface of the substrate where the metal contact plug is exposed, wherein the first dopants include one of Ge, Sn and Pb, which was previously absent from the substrate; and
performing, after the metal contact plug is formed, a second implantation process to implant a plurality of second dopants into the surface of the substrate where the metal contact plug is exposed, wherein the second dopants include one of carbon and fluorine, which was previously absent from the substrate.
11 . The method according to claim 10 , further comprising, after the step of performing the first implantation process, a step of performing an annealing process for restoring damages resulting from the first implantation process.
12 . The method according to claim 10 , wherein the step of forming the metal contact plug includes:
depositing a metal contact layer to fill the contact hole to form the metal contact plug; and
performing a chemical-mechanical planarization (CMP) process to reveal the surface of the substrate where the metal contact plug is exposed, and
wherein, after the CMP process, the first dopants are implanted into the surface of the substrate where the metal contact plug is exposed.
13 . The method according to claim 12 , further comprising, after the step of performing the first implantation process, a step of performing an annealing process for restoring damages resulting from the first implantation process.
14 . The method according to claim 10 , wherein the circuit component has a silicon-containing feature that is exposed from the bottom of the contact hole, and the method further comprises, after the dielectric liner layer is formed and before the metal contact plug is formed, steps of:
conformally depositing a metal film on the substrate and in the contact hole, thereby forming a silicide layer at an interface between the silicon-containing feature and the metal film;
transforming the metal film into a metal nitride film by a plasma treatment that uses a gas including nitrogen; and
removing a portion of the metal nitride film that is outside of the contact hole and a portion of the metal nitride film that is disposed on the sidewall of the contact hole, thereby forming a metal nitride layer at the bottom of the contact hole and over the silicide layer.
15 . The method according to claim 10 , wherein the second implantation process creates one of SiOC and SiOF in the substrate.
16 . A method for forming a metal contact plug, comprising steps of:
forming a circuit component in a frontside portion of a substrate, wherein the circuit component has a silicon-containing feature;
forming a contact hole in a backside portion of the substrate, wherein the backside portion of the substrate is made of Si or SiO 2 ;
forming a dielectric liner layer on a sidewall of the contact hole;
forming the metal contact plug in the contact hole in such a way that the dielectric liner layer is disposed between the metal contact plug and the substrate; and
implanting fluorine into the backside portion of the substrate after the metal contact plug is formed.
17 . The method according to claim 16 , further comprising steps of:
forming a silicide layer on the silicon-containing feature and at a bottom of the contact hole after the step of forming the dielectric liner layer and before the step of forming the metal contact plug; and
forming a metal nitride layer on the silicide layer after the step of forming the silicide layer and before the step of forming the metal contact plug,
wherein the step of forming the silicide layer includes:
conformally depositing a metal film on the substrate and in the contact hole, thereby forming the silicide layer at an interface between the silicon-containing feature and the metal film, and
wherein the step of forming the metal nitride layer includes:
transforming the metal film into a metal nitride film by a plasma treatment that uses a gas including nitrogen; and
removing a portion of the metal nitride film that is outside of the contact hole and a portion of the metal nitride film that is disposed on the sidewall of the contact hole, thereby forming the metal nitride layer at the bottom of the contact hole and over the silicide layer.
18 . The method according to claim 16 , wherein the step of forming the metal contact plug in the contact hole includes:
depositing a metal contact layer to fill the contact hole; and
performing, after depositing the metal contact layer, a planarization process to form the metal contact plug that is in contact with the dielectric liner layer in the contact hole, and to reveal the backside portion of the substrate that has a top surface where the metal contact plug is exposed.
19 . The method according to claim 16 , further comprising a step of implanting one of Ge, Sn and Pb into a top surface of the backside portion of the substrate after the metal contact plug is formed.
20 . The method according to claim 16 , wherein the fluorine, which was previously absent from the substrate, is implanted into a surface of the backside portion of the substrate where the metal contact plug is exposed,
the method further comprising a step of:
implanting, after the metal contact plug is formed, one of Ge, Sn and Pb, which was previously absent from the substrate, into the surface of the backside portion of the substrate where the metal contact plug is exposed.