Scandium oxide deposited by high-pressure sputtering for memory devices: Physical and interfacial properties

Abstract

Scandium oxide (ScOx) thin layers are deposited by high-pressure sputtering (HPS) for physical and electrical characterization. Different substrates are used for comparison of several ScOx/Si interfaces. These substrates are chemical silicon oxide (SiOx), H-terminated silicon surface and silicon nitride (SiNx), obtained by either electron-cyclotron-resonance chemical vapor deposition or plasma enhanced nitridation of the Si surface. Transmission electron microscopy images show that a 1.7 nm thick SiOx layer grows when ScOx is deposited on H-terminated silicon surface. We demonstrate that interfacial SiNx has some advantages over SiOx used in this work: its permittivity is higher and it presents better interface quality. It also avoids Si oxidation. An improvement of one order of magnitude in the minimum of interface trap density is found for SiNx with respect to the SiOx, reaching values below 2×1011 cm−2 eV−1. HPS deposited ScOx films are polycrystalline with no preferential growth direction for the used deposition conditions and their properties do not depend on the substrate. This material could be a candidate for high-k material in flash memory applications.

Electrical and chemical characterization of high pressure sputtered scandium oxide for memory applications

“…Thus, the flatband voltage of the curve measured from inversion to accumulation is shifted because positive charges that are trapped in the chemical oxide when the gate bias is negative. This agrees with the fact that the chemical oxide presents a density of defects higher than the other analyzed interfaces [11].…”

“…Taking into account only the Sc 2 O 3 contribution, the O to Sc ratio is 1.4 ± 0.1 in all cases. This is in agreement with GIXRD measurements, which showed a cubic bixbyite Sc 2 O 3 phase [11]. Capacitance-voltage hysteresis curves of the MOS capacitors are shown in fig.…”

Optimization of gadolinium oxide growth deposited on Si by high pressure sputtering

“…The rf power was chosen as 40 W since it was the rf power used in previous works for the scandium oxide. 18 This power was selected in order to obtain a reasonably high growth rate while minimizing substrate damage.…”

“…1,17 This work deals with electrical and structural analysis of gadolinium oxide films grown on Si by means of high pressure sputtering (HPS). 18 This system was demonstrated to be adequate for other high j dielectrics growth. [19][20][21] During the deposition process, the pressure is maintained in the 0.2-2 mbar range, about 3 orders of magnitude higher than in a conventional sputtering system.…”

Hydrogenated amorphous silicon deposited by high pressure sputtering for HIT solar cells

“…When we work in the high pressure range (~1 mbar), the atoms that are sputtered from the target with very high energy, collide with the gas atoms and reach the sample thermalized [7]. Therefore, we can deposit a-Si:H layers without sample damage, and form a high quality heterojunction between amorphous and crystalline silicon.…”