A semiconductor component includes a substrate having an opening. The semiconductor component further includes a first dielectric liner in the opening, wherein the first dielectric liner having a thickness T1 at a first end of the opening, and a thickness T2 at a second end of the opening, and R1 is a ratio of T1 to T2. The semiconductor component further includes a second dielectric liner over the first dielectric liner, wherein the second dielectric liner having a thickness T3 at the first end of the opening, a thickness T4 at the second end of the opening, R2 is a ratio of T3 to T4, and R1 is greater than R2.