Selective-area formation of Si microstructures using ultrathin SiO2 mask layers

“…In the Si CVD process, nucleation is known to be enhanced in such a Si-rich region. [16] Since the total pressure in the system and the flow rate of SiH 4 gas were kept at a constant level, the partial pressure of SiH 4 gas decreased with increasing N 2 flow rate, and the relative partial pressure ratio of N 2 to SiH 4 increased. Under this growth condition, the dot density is increased because the size of the silicon clusters is decreased when the number of silicon cluster nucleation sites is increased due to the large increase in silicon dangling bonds as discussed above.…”

mentioning

confidence: 99%

Growth and Size Control of Amorphous Silicon Quantum Dots Using SiH4/N2 Plasma

Park¹,

Kim²,

Sung³

et al. 2002

Chem. Vap. Deposition

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Recently, the optical properties of Si nanostructures have been the subject of intensive study. The strong photoluminescence (PL) from porous Si, [1,2] Si nanocrystals, [2,3] and amorphous Si quantum structures [4±6] prepared by a variety of methods has been the subject of particular attention from both the fundamental and practical points of view. Although several emission mechanisms from Si, including quantum size effect, defects, and Si-based chemical species such as siloxane and polysilane, have been proposed, [7±10] quantum size effect has been most frequently proposed as the origin of the PL, and the size control of Si quantum structures is an important factor in Si-based optoelectronic devices. Most studies have been focused on quantum wells [11±13] and self-assembled Si quantum dots (QDs) grown on an insulating surface [14±16] for the size control of Si quantum structures. However, these self-assembled Si QDs have a large lateral size, and the quantum size effect is negligibly small in the lateral direction compared to that of sphere-like QDs. Therefore, quantum well and self-assembled Si QD structures grown on the substrate are not suitable for optoelectronic applications in the short wavelength region because quantum size effect in these two structures is very small due to only one-dimensional size effect in the growth direction.Meanwhile, amorphous Si (a-Si) has two important advantages compared with bulk crystalline Si. Firstly, the luminescence efficiency of bulk a-Si is higher than that of crystalline Si because of its structural disorder. [17] In addition, the bandgap energy of bulk a-Si (1.6 eV) is larger than that of bulk crystalline Si (1.1 eV), thus making it a good candidate for short-wavelength device applications such as a blue light-emitting diode. Therefore, it would be expected that these intrinsic advantages of a-Si and the quantum confinement effect in the a-Si QD in three directions would lead to extremely useful optical properties in short-wavelength devices. [18] In this study, a silicon nitride film was used as a matrix material to embed a-Si QDs. A silicon nitride film is expected to be better than silicon oxide in optical device applications because carriers can be easily transported to the a-Si QDs in the silicon nitride matrix due to the lower tunneling barriers for electrons and holes of silicon nitride than those of silicon oxide. [11] We report here on the growth and size control of a-Si QDs embedded in the silicon nitride film by plasma enhanced (PE) CVD. Figure 1 shows the Raman spectrum, that can be separated into two components. One peak in the vicinity of 460 cm ±1 is assigned to the asymmetric Si±N bond stretching mode in the silicon nitride matrix, and the other peak in the vicinity of 490 cm ±1 corresponds to scattering with localized optical phonons that exist in silicon QDs surrounded by nitrogen atoms. [19] Compared to those from bulk materials, these two peaks are also shifted to the highenergy side by about 10 cm ±1 , due to the compressive strain normally p...

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“…Selective-area epitaxial growth of Si, GaAs, and GaN has been demonstrated in the past using the nitride masks on various substrates. However, for Si growth using SiH 4 or Si 2 H 6 , SiO 2 is a better mask material than Si 3 N 4 because of the superior growth suppression effect of the former material [5]. Here we demonstrate a Si CVD process using a novel SiO 2 /Si 3 N 4 bilayer mask.…”

Section: Resultsmentioning

confidence: 99%

“…The relative humidity was around 50-60% during the AFM oxidation. The selective epitaxial growth was performed in an ultrahigh vacuum (UHV) CVD reactor system [3][4][5]. Figure 1a shows an AFM-induced oxide dot array with an areal density of $100 Gbits/inch 2 on the Si 3 N 4 film, which was produced by applying voltage pulses of +9 V and 5 ms duration to the sample.…”

mentioning

confidence: 99%

Nanometer-Scale Conversion of Si3N4 to SiOx for Applications in Lithography, Micromachining, and Selective-Area CVD

Gwo

Chen

Yasuda³

et al. 2001

phys. stat. sol. (a)

Self Cite

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We present the use of scanning probe oxidation of Si 3 N 4 masks for performing nanolithography, nanomachining, and nanoscale epitaxial growth on silicon. Three most unique features of this approach are presented: (i) exceptionally fast oxidation kinetics using silicon nitride masks ($30 mm/s at 10 V for a %5 nm thick film), (ii) selective-area anisotropic etching of Si using a Si 3 N 4 etch mask, (iii) selective-area chemical vapor deposition of Si using a SiO 2 /Si 3 N 4 bilayer growth mask.Introduction Silicon nitride is widely used as a dielectric material for semiconductor very-large-scale integration processing due to its many superior material properties. In one of the most important applications using Si 3 N 4 , it is used as an oxidation mask (oxidation rate is about 100 times less than silicon) during the local oxidation of silicon (LOCOS) process. Because of the large selectivities of many etchants of silicon and SiO 2 over Si 3 N 4 , it can be a versatile wet or dry etching mask for nanofabrication if a local oxidation scheme can be developed. Furthermore, both Si 3 N 4 and SiO 2 are important mask materials for selective-area growth of semiconductors and metals. Therefore, the possibility of performing local oxidation on nitride masks could open up a wide variety of new applications. Recently, we have successfully demonstrated that ultrathin Si 3 N 4 films could be effectively converted to SiO x by the atomic force microscope (AFM)-induced local oxidation in air with an absorbed humidity layer. The threshold voltage for complete conversion of a %5 nm thick film is as low as 7 V [1, 2].

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Selective-area formation of Si microstructures using ultrathin SiO2 mask layers

Cited by 23 publications

References 16 publications

Chemical vapor deposition of Si on chlorosilane-treated SiO2 surfaces. II. Selective deposition in the regions defined by electron-beam irradiation

Chemical vapor deposition of Si on chlorosilane-treated SiO2 surfaces. II. Selective deposition in the regions defined by electron-beam irradiation

Growth and Size Control of Amorphous Silicon Quantum Dots Using SiH4/N2 Plasma

Nanometer-Scale Conversion of Si3N4 to SiOx for Applications in Lithography, Micromachining, and Selective-Area CVD

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