A method of making a semiconductor device includes forming a first source/drain trench and a second source/drain trench over a first and second source/drain region, respectively; forming a first silicon dioxide layer in the first source/drain trench and a second silicon dioxide layer in the second source/drain trench; forming a first source/drain contact over the first source/drain region, the first source/drain contact including a first tri-layer contact disposed between the first silicon dioxide layer and a first conductive material; and forming a second source/drain contact over the second source/drain region, the second source/drain contact including a second tri-layer contact disposed between the second silicon dioxide layer and a second conductive material; wherein the first tri-layer contact includes a first metal oxide layer in contact with the first silicon dioxide layer, and the second tri-layer contact includes a second metal oxide layer in contact with the second silicon dioxide layer.