Aluminum nitride thin films deposited by hydrogen plasma enhanced and thermal atomic layer deposition

Plasma enhanced atomic layer deposition (PE-ALD) of aluminum nitride (AlN) thin films often utilizes NH3 or a mixture of N-2 and H-2 as a plasma source. However, the possibility of separating the activation step from the nitridation step by using H-2 alone as the plasma source has never been explored. In this paper, we study the deposition of MN by PE-ALD by using trimethylaluminum, H-2 plasma and NH3 for deposition temperatures below 400 degrees C. The self-limiting ALD growth was achieved between 325 degrees C and 350 degrees C. As a comparison, AIN was also deposited by thermal ALD (T-ALD), where surface reactions between TMA and NH3 occurred with reasonable growth rates only at temperatures above 400 degrees C. The PE-ALD films showed low oxygen (1.5 at.%) and carbon contaminations (1 at.%). The T-ALD films contained carbon (5 at.%) mainly attributed to the presence of C-Al bonds that was insignificant in PE-ALD films. The flow rate of H-2 used in H-2 plasma was found to have a significant impact on the preferred orientation of MN films, where higher H-2 flow rate promoted the (002) preferred orientation. Besides, the electrical resistivities were probed to be 1085 cm, as expected in an insulating material. As an example, AlN was used to infiltrate porous sintered silicon carbide (SiC). Both AIN deposited by PE-ALD and by T-ALD operating with exposure mode deposited at 400 degrees C were attempted. Even though, there is a greater risk for TMA precursor to decompose at 400 degrees C, infiltration of MN was more successful by T-ALD operating with exposure mode.