Detailed study of the effects of interface properties of ozone-based atomic layer deposited AlO_x on the surface passivation of crystalline silicon

Abstract

The effects of interface properties such as a negative fixed charge density and an interface trap density on the surface passivation of crystalline Si by O3-based batch ALD AlO x were studied. High-quality surface passivation with S max of ∼10 cm/s was obtained from the AlO x samples deposited at 200 °C after annealing. This feature is attributed to the excellent field effect passivation by the high negative fixed charge density of ∼−5 × 1012 cm−2 and chemical passivation, which reduces the interface trap density to ∼1 × 1011 eV−1 cm−2. The annealed AlO x samples deposited at 200 °C also show high thermal stability during firing at 850 °C. Additionally, we found that the formation of a thin SiO x interlayer is essential for the formation of a high negative fixed charge density that induces strong field effect passivation, and that defect passivation at the Si/SiO x interface by diffused hydrogen from AlO x layers is the origin of chemical passivation.

Near-Ideal Top-Gate Controllability of InGaZnO Thin-Film Transistors by Suppressing Interface Defects with an Ultrathin Atomic Layer Deposited Gate Insulator

“…As mentioned above, the Al−OH bonds were introduced into the AlO x films when TMA reacted with O 3 during the ALD process. 58,59 Under PBS, the −OH groups in ALD AlO x near the GI/channel interface can be dissociated by the energetic channel electrons (process [1]), 60 and then the H atoms cleaved from the −OH bonds diffuse into a-IGZO to elevate the channel carrier concentration (process [2]), 61,62 as shown in Figure 6d. Meanwhile, the hydrogen-related defects at the interface can also serve as electron traps, 63 leading to a deteriorated SS under PBS.…”

Effect of post-deposition annealing on electrical properties and structures of aluminum oxide passivation film on a crystalline silicon substrate

“…Although AlO x has been studied as a candidate for gate dielectric since the 1970s, research on AlO x for passivation films has been active since the mid-2000s, because the AlO x film on c-Si showed excellent surface passivation property. This high level of surface passivation is attributed to the field-effect passivation induced by a high negative fixed charge density, regardless of the deposition techniques, such as atomic layer deposition (ALD), [8][9][10][11][12][13][14][15][16][17] plasma-enhanced CVD, [18][19][20] mist CVD, 21) pyrolysis 7) and sputtering. 22,23) In most cases, post-deposition annealing (PDA), so called "activation" was carried out to obtain such excellent surface passivation property.…”

Investigation of new stacking surface passivation structures with interfacial tuning layers on p-type crystalline silicon

“…[14][15][16][17][18][19][20][21][22] This is confirmed, for example, by the result that the negative fixed charge formation was completed with Al 2 O 3 thicknesses less than 10-20 nm and further thickness increase showed field effect saturation. [23][24][25] Therefore, the YZO=Al 2 O 3 stacking structure should provide the two benefits of negative fixed charge in the film and an electric dipole at the interface, resulting in superior field effect passivation. 26,27) We have confirmed, however, that the interdiffusion of Al and Y occurred and deteriorated the passivation properties, especially after hightemperature thermal treatment.…”