Air carrier Captain reported a loss of aircraft steering control when taxiing to the gate with an icy and wet contaminated ramp surface while on a single engine taxi. The Captain stopped the aircraft; then called for a tug assist to continue to the gate with no damage.

Narrative

While parking at Gate XX at ORD we encountered an extremely slippery gate area; causing very poor steering control. We taxied in from the runway (28C) using two engines due to a small amount of compacted snow on the taxiways. The gate area looked wet and the centerline was salted heavily. As there appeared to be no ice or snow there; I instructed to the FO to shut down engine number 2. About 20 feet from the gate the nose wheel skidded and I felt a loss of traction. We were already going very slowly (probably 3-4 kt); and I slowed down and stopped. We tried to move forward again and made it a few feet but I had very little steering ability so we stopped; set the parking brake and requested a tug from ops to tow us in. The salt on the centerline appeared to have de-ice fluid in it and when the nose wheel compressed it it became became very slick. We did not get close to any obstacles; but a tow in from that point was the safest option. The ground crew got a tug and pulled us in about 5 minutes after we set the brake. We deplaned uneventfully.