| Summary: | 碩士 === 國立雲林科技大學 === 電子與資訊工程研究所 === 93 === This experiment is planned to utilize sputtering method to deposit ultrathin metal Hf or HfN in silicon basis, then, utilize anodization to make metal layer change into hafnium oxide (HfO2) and hafnium oxynitride (HfON) at room temperature. Whether the parameter controlled have two: one for oxidize time it is 10min, 12min, 16min and 18min respectively; Another for oxidize electric field 5V/cm, 10V/cm, 20V/cm and 30V/cm, is it make condition to lie between electricity layers of influence of quality initial stage to compare.
Experiment result of study show, in deposited metal (Hf) it is formed oxidize membrane of hafnium oxide (HfO2), the parameter to oxidize the electric field or oxidize time, for its equivalent thickness (EOT) or the dielectric constant (k) all returns to the effect (turn-around effect), namely E＝10V/cm reaches EOT to maximize and minimize with k value. This interesting phenomenon is connected compositions of the interface layer (IL) from SiOX to Hf-Si:O mainly, it is influenced that the composition changes. However, the membrane that the hafnium oxynitride (HfON) is formed from deposited metal (HfN), quite different growth changes appear. In the low intensity of electric field, EOT nearly maintains the minimization. By inference this separates the oxygen atom and spreads and enters and connects the reason that the face combines with the silicon with atom of nitrogen effectively, and is analyzed that can find out that in N1s, there is indirect evidence that Si and key of N form by XPS; While oxidizing the electric field to strengthen, include key that nitrogen correlated with is it interrupt to form, is it connect interface layer low to lie between electric area increase in a large amount to make, namely the atom of nitrogen is not enough to prevent the oxygen atom from combining with the silicon, cause EOT rising by a wide margin, connect the density of electric charge of interface (Dit) at this moment and also rise. Utilize conductance method, it may take Dit distribution of the silicon step. Compare with density in Dit(midgap ), oxidizing electric field E＝5V/cm and oxidizing time 12min, HfO2 is 6.02×1012cm-2eV-1 and HfON is 2.17×1012 cm-2eV-1, Dit of HfON is about 1/4 of HfO2.
Direct HfO2 and HfON the two optimization, so choose E＝5V/cm and the oxidizing time 12min to proceed annealing treatment, in order to study its influence of stability. The experiment is found, under proper annealing temperature (T＝600℃), it can really make k value rise and drop with EOT, but HfON has better stability. As for change amount of k value, it is 16.15 before annealing and 24.01 after annealing for HfO2, the change amount of HfO2 is 48.67%, and it is 17.48 before annealing and 24.54 after annealing for HfON, the change amount of HfON is 40.39%; As for change amount of EOT, it is 26.9 before annealing and 17.9 after annealing for HfO2, the change amount of HfO2 is 33.46%, and it is 16 before annealing and 15 after annealing for HfON, the change amount of HfON is 6.25%; As for change amount of hysteresis voltage (VH), it is 95mV before annealing and 286mV after annealing for HfO2, the change amount of HfO2 is 201%, and it is 43mV before annealing and 55mV after annealing for HfON, the change amount of HfON is 28%, and to leakage electric current about to rise one nearly the two.
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