Selective capping of contact layer for CMOS devices
A method of forming an electrical contact in a semiconductor structure includes performing a patterning process to form a hard mask on a semiconductor structure comprising a first semiconductor region, a second semiconductor region, a dielectric layer having a first opening over the first semiconductor region and a second opening over the second semiconductor region, wherein the hard mask covers an exposed surface of the first semiconductor region within the first opening, performing a first selective deposition process to form a contact layer on the exposed surface of the second semiconductor region within the second opening, and performing a second selective deposition process to form a cap layer on the contact layer.
1 . A method of forming an electrical contact in a semiconductor structure, comprising:
performing a patterning process to form a hard mask on a semiconductor structure comprising a first semiconductor region, a second semiconductor region, a dielectric layer having a first opening over the first semiconductor region and a second opening over the second semiconductor region, wherein the hard mask covers a surface of the first semiconductor region within the first opening and exposes a surface of the second semiconductor region within the second opening;
performing a first selective deposition process to form a contact layer on the exposed surface of the second semiconductor region within the second opening; and
performing a second selective deposition process to form a cap layer on the contact layer.
2 . The method of claim 1 , wherein
the first semiconductor region comprises silicon doped with n-type dopants,
the second semiconductor region comprises silicon germanium doped with p-type dopants, and
the contact layer comprises silicon germanium doped with p-type dopants.
3 . The method of claim 1 , wherein
the cap layer comprises material selected from molybdenum (Mo) silicide and ruthenium (Ru) silicide.
4 . The method of claim 1 , further comprising:
prior to the patterning process, performing a pre-clean process on the surface of the first semiconductor region within the first opening and the surface of the second semiconductor region within the second opening.
5 . The method of claim 1 , further comprising:
prior to the first selective deposition process, performing an etch process to form a groove at the exposed surface of the second semiconductor region, wherein the groove has a V shape, a U shape, and any other shape to enlarge a contact area of the contact layer.
6 . The method of claim 5 , wherein
the first selective deposition process, the second selective deposition process, and the etch process are performed without breaking vacuum environment.
7 . The method of claim 1 , further comprising:
subsequent to the second selective deposition process, performing a removal process to remove the hard mask;
performing a third selective deposition process to form a metal layer on the exposed surface of the first semiconductor region and the cap layer; and
performing a metal fill process to form a first contact plug in the first opening and a second contact plug in the second opening.
8 . The method of claim 7 , wherein
the metal layer comprises material selected from titanium (Ti) silicide, cobalt (Co) silicide, nickel (Ni) silicide, molybdenum (Mo) silicide, and tantalum (Ta) silicide.
9 . A method of forming an electrical contact in a semiconductor structure, comprising:
performing a pre-clean process on surfaces of a semiconductor structure comprising a first semiconductor region, a second semiconductor region, a dielectric layer having a first opening over the first semiconductor region and a second opening over the second semiconductor region;
performing a patterning process to form a hard mask on the semiconductor structure, wherein the hard mask covers the surface of the first semiconductor region within the first opening and exposes the surface of the second semiconductor region within the second opening;
performing an etch process to form a groove at the exposed surface of the second semiconductor region;
performing a first selective deposition process to form a contact layer on the exposed surface of the second semiconductor region within the second opening;
performing a second selective deposition process to form a cap layer on the contact layer;
performing a removal process to remove the hard mask and expose the surface of the first semiconductor region within the first opening;
performing a third selective deposition process to form a metal layer on the exposed surface of the first semiconductor region and the cap layer; and
performing a metal fill process to form a first contact plug in the first opening and a second contact plug in the second opening.
10 . The method of claim 9 , wherein the etch process, the first selective deposition process, and the second selective deposition process are performed without breaking vacuum environment.
11 . The method of claim 9 , wherein
the first semiconductor region comprises silicon doped with n-type dopants,
the second semiconductor region comprises silicon germanium doped with p-type dopants, and
the contact layer comprises silicon germanium doped with p-type dopants.
12 . The method of claim 9 , wherein
the cap layer comprises material selected from molybdenum (Mo) silicide and ruthenium (Ru) silicide.
13 . The method of claim 9 , wherein
the metal layer comprises material selected from titanium (Ti) silicide, cobalt (Co) silicide, nickel (Ni) silicide, molybdenum (Mo) silicide, and tantalum (Ta) silicide.
14 . A processing system, comprising:
a first processing chamber;
a second processing chamber;
a third processing chamber; and
a system controller configured to cause the processing system to:
perform, in the first processing chamber, a patterning process to form a hard mask on a semiconductor structure comprising a first semiconductor region, a second semiconductor region, a dielectric layer having a first opening over the first semiconductor region and a second opening over the second semiconductor region, wherein the hard mask covers on a surface of the first semiconductor region within the first opening and exposes a surface of the second semiconductor region within the second opening;
perform, in the second processing chamber, a first selective deposition process to form a contact layer on the exposed surface of the second semiconductor region within the second opening; and
perform, in the third processing chamber, a second selective deposition process to form a cap layer on the contact layer.
15 . The processing system of claim 14 , further comprising:
a fourth processing chamber, wherein the system controller is further configured to:
prior to the first selective deposition process, perform, in the fourth processing chamber, an etch process to form a groove at the exposed surface of the second semiconductor region, wherein the groove has a V shape, a U shape, and any other shape to enlarge a contact area of the contact layer.
16 . The processing system of claim 15 , wherein the system controller is further configured to cause the processing system to transfer the semiconductor structure among the second, third, and fourth processing chambers without breaking vacuum environment.
17 . The processing system of claim 15 , further comprising:
a fifth processing chamber, wherein the system controller is further configured to:
prior to the patterning process, perform, in the fifth processing chamber, a pre-clean process on the exposed surface of the first semiconductor region within the first opening and the exposed surface of the second semiconductor region within the second opening.
18 . The processing system of claim 17 , further comprising:
a sixth processing chamber;
a seventh processing chamber; and
an eighth processing chamber, wherein the system controller is further configured to cause the processing system to:
subsequent to the second selective deposition process, perform, in the sixth processing chamber, a removal process to remove the hard mask;
perform, in the seventh processing chamber, a third selective deposition process to form a metal layer on the exposed surface of the first semiconductor region and the cap layer; and
perform, in the eighth processing chamber, a metal fill process to form a first contact plug in the first opening and a second contact plug in the second opening.
19 . The processing system of claim 14 , wherein
the first semiconductor region comprises silicon doped with n-type dopants,
the second semiconductor region comprises silicon germanium doped with p-type dopants, and
the contact layer comprises silicon germanium doped with p-type dopants.
20 . The processing system of claim 14 , wherein
the cap layer comprises material selected from molybdenum (Mo) silicide and ruthenium (Ru) silicide.