Abstract: A device includes: a complementary transistor including: a first transistor having a first source/drain region and a second source/drain region; and a second transistor stacked on the first transistor, and having a third source/drain region and a fourth source/drain region, the third source/drain region overlapping the first source/drain region, the fourth source/drain region overlapping the second source/drain region. The device further includes: a first source/drain contact electrically coupled to the third source/drain region; a second source/drain contact electrically coupled to the second source/drain region; a gate isolation structure adjacent the first and second transistors; and an interconnect structure electrically coupled to the first source/drain contact and the second source/drain contact.

Abstract: Semiconductor structures and methods of forming the same are provided. In an embodiment, an exemplary method includes forming a dummy gate stack engaging a semiconductor fin over a substrate, conformally depositing a first dielectric layer over the substrate, conformally depositing a second dielectric layer over the first dielectric layer, etching back the first dielectric layer and the second dielectric layer to form a gate spacer extending along a sidewall surface of the dummy gate stack, the gate spacer comprising the first dielectric layer and the second dielectric layer, forming source/drain features in and over the semiconductor fin and adjacent the dummy gate stack, and replacing the dummy gate stack with a gate structure, where a dielectric constant of the first dielectric layer is less than a dielectric constant of silicon oxide, and the second dielectric layer is less easily to be oxidized than the first dielectric layer.

Abstract: A memory circuit includes a memory cell and a source line transistor. The memory cell includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The second transistor and the third transistor form an inverter electrically connected to a drain of the first transistor. The inverter is configured to store two states with different applied voltages. The fourth transistor is electrically connected to a node of the inverter. The source line transistor is electrically connected to the fourth transistor.

Abstract: A method includes forming a first transistor, a second transistor, a third transistor, and a fourth transistor over a substrate, wherein at least the second and third transistors include ferroelectric materials; forming an interlayer dielectric (ILD) layer over the first to fourth transistors; forming a first metal line over the ILD layer to interconnect drains of the second and third transistors and a gate of the fourth transistor; forming a second metal line over the ILD layer to interconnect a drain of the first transistor and gates of the second and third transistors; forming a write word line over the ILD layer and electrically connected to a gate of the first transistor but electrically isolated from the fourth transistor; forming a word line over the ILD layer and electrically connected to a source of the first transistor; and forming a bit line electrically connected to the fourth transistor.

Abstract: A memory circuit includes a memory cell and a source line transistor. The memory cell includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The second transistor and the third transistor form an inverter electrically connected to a drain of the first transistor. The inverter is configured to store two states with different applied voltages. The fourth transistor is electrically connected to a node of the inverter. The source line transistor is electrically connected to the fourth transistor.