Aspects of the disclosure provide a semiconductor device. The semiconductor device can include a trench formed in a first dielectric layer, a trench filler layer that fills a portion of the trench, a conductive layer over the trench filler layer, and a second dielectric layer over the conductive layer. The second dielectric layer is disposed in the trench. The semiconductor device can also include a contact structure configured to connect to the conductive layer through a hole in the second dielectric layer.