Thermochemical behavior of hydrogen in hafnium silicate films on Si

HfSiO films on Si were sequentially annealed in vacuum, oxygen, hydrogen, or deuterium atmospheres followed by quantification of H and D by nuclear reaction analysis. The observed H(D) incorporation and desorption behaviors are discussed in terms of two H bonding states in the films. Si–H bonds are easier to break thermally and formation of these bonds can be suppressed by annealing in O2 to fully oxidize Si atoms. O–H bonds are harder to break thermally. However, hydrogen atmospheres ease desorption of H in O–H species. The results indicate possible paths to achieve low H content in HfSiO gate dielectrics.