Formation process of Si3N4 particles on surface of Si ingots grown using silica crucibles with Si3N4 coating by noncontact crucible method

Abstract

A noncontact crucible method was used to investigate the process by which a Si 3 N 4 coating material forms Si 3 N 4 particles or precipitates on the surface of Si melts and ingots. Si ingots were grown using crucibles with and without a mixture of α-and β-Si 3 N 4 particles. The oxygen and nitrogen concentrations in the ingots were measured by Fourier transform infrared spectrometry analysis. The nitrogen concentration in the ingots grown using crucibles with a Si 3 N 4 coating was significantly higher than that in ingots grown using crucibles without a Si 3 N 4 coating because the nitrogen from the Si 3 N 4 coating material dissolved into the Si melt. From orientation image maps analyzed using electron backscattering diffraction patterns of Si x N y particles on the surface of the ingots, it was clarified that most of the Si x N y particles were β-Si 3 N 4. This was also confirmed by X-ray diffraction measurements. The Si 3 N 4 particles on the surface of the ingots had several morphologies such as needle-like, columnar, leaf-like, and hexagonal structures. There were two cases in which floating Si 3 N 4 particles were formed on the surface of the Si melts, i.e., the removal and dissolution of the Si 3 N 4 coating material. The removed or dissolved Si 3 N 4 coating materials, which consisted of a mixture of α-and β-Si 3 N 4 particles, are considered to have finally changed into β-Si 3 N 4 in the form of transformers or precipitates on the surface of the Si melt, and these β-Si 3 N 4 particles became attached to the surface of the ingots.

Shape and quality of Si single bulk crystals grown inside Si melts using the noncontact crucible method

“…The starting temperature was accurately determined by directly observing the melt surface near the seed through the windows of the furnace chamber, while the actual temperature reduction was read from the monitor of the heater system used. [1][2][3][4][5][6] The total temperature reduction ¦T t (K), defined as the difference between the starting temperature at which the initial crystal was first observed and the final temperature at which the crystal growth was terminated by separating the ingot from the remaining Si melt, required for the complete growth of the ingots was between 12.5 and 51.3 K. A large ¦T t is important for obtaining ingots with a large diameter. [1][2][3][4]6) The cooling rate was set to be in the range of 0.17-0.2 K min ¹1 .…”

“…The noncontact crucible method [1][2][3][4][5][6] enables production of Si bulk single crystals without crucible contact by intentionally establishing a distinct low-temperature region in the Si melt. In contrast to the Czochralski (CZ) method, 7) the noncontact crucible method enables the control of ingot shape by regulating the degree and distribution of undercooling in the melt and the pulling speed.…”

Growth of Si Bulk Crystals with Large Diameter Ratio Using Small Crucibles by Creating a Large Low-Temperature Region Inside a Si Melt Contained in an NOC Furnace Developed Using Two Zone Heaters

“…[1][2][3][4][5][6][7][8] This method is similar to the Kyropoulos method. [9][10][11] In the NOC method, however, a low-temperature region must be intentionally established in a Si melt.…”