Method of forming a contact in a semiconductor device with engineered plasma treatment profile of barrier metal layer
View Patent ↗A method of forming a contact in a semiconductor device provides a titanium contact layer in a contact hole and a MOCVD-TiN barrier metal layer on the titanium contact layer. Impurities are removed from the MOCVD-TiN barrier metal layer by a plasma treatment in a nitrogen-hydrogen plasma. The time period for plasma treating the titanium nitride layer is controlled so that penetration of nitrogen into the underlying titanium contact layer is substantially prevented, preserving the titanium contact layer for subsequently forming a titanium silicide at the bottom of the contact.
1. A method of forming a contact in a semiconductor device, comprising the steps:
forming a contact hole in a dielectric layer on a substrate containing a conductive region, the contact hole exposing a portion of the conductive region;
forming a contact layer in the contact hole and on the conductive region portion;
forming a barrier metal layer on the contact layer;
plasma treating the barrier metal layer with a nitrogen-hydrogen plasma such that penetrated nitrogen concentration in the contact layer is less than 30 at. %; and
forming a silicide region at the conductive region portion by reacting the contact layer with the conductive region portion,
wherein the contact layer is titanium and the barrier metal layer is titanium nitride, the barrier metal layer is deposited to a thickness of between 25 to about 60 Å, the plasma is an N 2 /H 2 plasma, the plasma treating includes exposing the barrier metal layer to the N 2 /H 2 plasma for a period of between 15 and 35 seconds, and providing RF power between 700 and 850 W.
2. The method of claim 1 , wherein the barrier metal layer is exposed to the N 2 /H 2 plasma with RF power provided of about 750 W.
3. A method of forming a contact in a semiconductor wafer, comprising the steps:
forming a titanium layer in a contact hole and on a conductive region portion of a substrate exposed by the contact hole;
forming a titanium nitride layer on the titanium layer; and
plasma treating the titanium nitride layer with a nitrogen-hydrogen plasma with treatment conditions preventing penetration of nitrogen into the titanium layer,
wherein the treatment conditions include a plasma exposure time of between about 15 to about 25 seconds and an RF power between about 700 and about 850 W.
4. The method of claim 3 , further comprising annealing the semiconductor wafer to cause the titanium layer to react with the conductive region portion to form titanium silicide.
5. A method of forming a contact in a semiconductor wafer, comprising the steps:
forming a contact layer in a contact hole and on a conductive region portion of a substrate exposed by the contact hole;
forming a barrier metal layer on the contact layer to a thickness;
plasma treating the barrier metal layer with a nitrogen-hydrogen plasma for a determined amount of time based on the thickness of the barrier metal layer so as to remove impurities from the barrier metal layer and substantially prevent nitrogen from penetrating into the contact layer; and
forming a silicide at the conductive region portion,
wherein the contact layer is titanium and the barrier metal layer is titanium nitride, RF power is maintained at about 750 W and the titanium nitride is exposed to the nitrogen-hydrogen plasma for 15 to 35 seconds for every 25 to 60 Å of thickness of the barrier metal layer, and the nitrogen-hydrogen plasma is an N 2 /H 2 plasma.