Novel Epitaxy for Nitride Semiconductors Using Plasma Technology

Abstract

For the production of nitride‐based optical and power devices, it is known that metal organics chemical vapor deposition (MOCVD) is an industrial method which is used worldwide. However, MOCVD has disadvantages: 1) a lot of ammonia gas is consumed; 2) the sublimation of GaN is not negligible at growth temperature and these increase the production cost; 3) the growth of in‐containing nitrides is difficult because the growth temperature is too high; and 4) using large Si substrates of 150–300 mm diameter for industrial production, wafer breakage and bowing occur. It is therefore important to develop novel epitaxial growth methods that can replace the MOCVD method. Recently, high‐density radical source (HDRS) is developed by combining inductively coupled plasma (ICP) and capacitively coupled plasma (CCP) which can be applied to molecular beam epitaxy (MBE) in order to increase the growth rate of nitrides. Another novel method, the radical enhanced MOCVD (REMOCVD) method with using very high frequency (VHF) plasma, has also been developed. This REMOCVD allows the low growth temperature without using any ammonia gas. These novel methods are promising for replacing the MOCVD method from the viewpoint of production cost without ammonia gas usage.

Epitaxial growth of high-quality GaN with a high growth rate at low temperatures by radical-enhanced metalorganic chemical vapor deposition

“…To date, few studies have been carried out to optimize growth conditions for high-quality GaN films in the N 2 /H 2 PEMOCVD 8 , 10 , 13 , 15 , 19 . We have however used a mixture gas of H 2 and N 2 to optimize the growth conditions 27 . The advantage of this gas mixture will be the formation of ammonia radical species (NH x ).…”

“…The REMOCVD system was described in detail elsewhere 26 , 27 and Fig. 1 shows the experimental arrangement of the REMOCVD system for the present work.…”

“…Therefore, we have developed a novel REMOCVD method 26 , 27 , in which nitrogen and hydrogen gas can be exited in plasma, and nitrides can be grown by the reaction between radicals and metal–organic (MO) gas. Presently, industrial equipment for large-diameter substrates of 150–300 mm is required for applications to power devices and low-cost LEDs 28 – 30 .…”

“…We have grown GaN, AlN, InN and AlInN layers by this REMOCVD method 26 , 27 , 31 – 64 and found that it is very effective to grow these nitrides at much lower temperatures than those of the MOCVD method without using any ammonia gas. It can be proved that the crystal quality is close to that of MOCVD even though the growth temperature is much lower 27 .…”

Perspectives on functional nitrogen science and plasma-based in situ functionalization

“…Nitrides Nitrides are another class of nitrogen-containing compounds based on metal-nitrogen bonds. Examples include boron nitride, [37][38][39][40] carbon nitride, [41][42][43][44][45] silicon nitride, 46) gallium nitride, [47][48][49][50][51][52][53] indium nitride, 54) aluminum nitride, iron nitride, titanium nitride, tantalum nitride, tungsten nitride and hafnium nitride. Methods for the deposition of atomic layers of these compounds are listed in Ref.…”