UC San Diego

Nanoscale fabrication is the key issue in the fabrication of leading-edge commercial semiconductor devices. Selective deposition methods are being developed to use in conjunction with double patterning techniques for nanoscale patterning. The need for selective deposition is acute in backend metallization when multiple metals and low k dielectric layers (SiCOH) with high aspect ratios are employed. The selective oxide deposition can also be applied in nanoscale fabrication for various purposes, such as etch stop layer and dielectric-on-dielectric structure. For selective oxide deposition in backend fabrication, water-free deposition is more desirable since it can not only induce higher selectivity but also prevent damage to metals and SiCOH.This study studied the inherent selective deposition of various oxides on Si and SiO2 in preference to SiCOH. SiCOH is alkyl (-CxHy) terminated SiO2, used as a non-reactive surface. Through the reactivity difference between precursors and different surfaces, inherent selective deposition was achieved. The selective oxide deposition was also tested in the nm scale patterned region to check whether the process can be applied in nanoscale fabrication. Chapter 1 of this dissertation describes the inherent selective TiO2 deposition process. The process showed >10 nm of selective TiO2 deposition and insight into using metal alkoxide precursor in a single precursor pulsed thermal CVD process. However, the TiO2 CVD process showed the limit of the process; the selectively deposited TiO2 film became rough due to the crystallization. Chapter 2 of this dissertation describes the inherent selective HfO2/TiO2 nanolaminates pulsed CVD process. To solve the film roughness issue from Chapter 1, the nanolaminate structure of two different oxides was studied. The selective HfO2/TiO2 nanolaminate CVD process showed >10 nm of selective and amorphous HfO2/TiO2 nanolaminate deposition, which obtained selective deposition and smooth film. Chapter 3 of this dissertation describes the inherent selective AlOx pulsed CVD process. As AlOx stays amorphous when the thickness increases and is easier to etch compared to the nanolaminate structure of two different oxides from Chapter 2, this process can be an ideal selective oxide deposition process for nanoscale fabrication as a spacer or etch stop layer.