ECR plasma CVD

An ECR-plasma CVD method is used to provide a protective film 27 on the mesas except for an exposed part of the pn-junction 26. ... 

In Refs. [253-255], BEN experiments were done by ECR plasma CVD under conditions shown in Table H.2. The substrate was a heteroepitaxial p-SiC(lOO) layer of 0.5-pm thickness deposited on Si [256] by low pressure CVD (LPCVD). Like in... 

It seems to have been established that the bias to the substrate is important in increasing the cBN yield in the case of RF plasma CVD (277), electron cyclotron resonance (ECR) plasma CVD (277,280,290,291), and inductively coupled RF plasma (ICP) CVD (279,292). A suitable amount of dilution gas such as Ar and a high ion flux to the substrate promote cBN formation (263,280). The hydrogen content in the gas needs to be small because BN deposition with a bias was difficult due to etching of the film by the gas (Fig. 46) (292). 

Without the bias, formation of cBN (or hard BN) was reported with ECR plasma CVD (293), microwave plasma CVD (275,294), RF plasma CVD with a thermal activation filament (295), and reactive evaporation of B or H3BO3 in an NH3 discharge (296-298). The amount of cBN in an hBN or tBN matrix of these films appears to be snoaUer than that of the films made with bias control. Ion beam deposition from a borazine (B3N3H) plasma (299) or from ionized borazine (264,270,300) was also reported to produce a hard BN material. 

Like synthetic diamond, C-BN is normally obtained by high-pressure processing. Efforts to synthesize it by CVD at low pressure are promising. It is deposited in an electron-cyclotron-resonance (ECR) plasma from a mixture of BF3 and either ammonia or nitrogen at 675°C on an experimental basis.F l Like CVD diamond, it is also deposited by the hot-filament method using diborane and ammonia diluted with hydrogen at 800°C.P 1... 

Some of the most significant developments in the CVD of Si02 include experiments in plasma CVD at 350°C via electron cyclotron resonance (ECR) to gain improved control of the deposition rate and obtain a quality equivalent to that of the thermally grown oxide (see Ch. 5). Deposition from diacetoxyditertiarybutoxy silane at 450°C has also been shown to significantly improve the Si02 film properties. " ]... 

In further sections extensions or adaptations of the PECVD method will be presented, such as VHF PECVD [16], the chemical annealing or layer-by-layer technique [17], and modulation of the RF excitation frequency [18]. The HWCVD method [19] (the plasmaless method) will be described and compared with the PECVD methods. The last deposition method that is treated is expanding thermal plasma CVD (ETP CVD) [20, 21]. Other methods of deposition, such as remote-plasma CVD, and in particular electron cyclotron resonance CVD (ECR CVD), are not treated here, as to date these methods are difficult to scale up for industrial purposes. Details of these methods can be found in, e.g., Luft and Tsuo [6]. 

Lastly, if the SiOj deposition is highly conformal, the regions between closely spaced metal lines may be filled without the production of gaps. If the film thickness is equal to half the space width, the space will fill completely and the comers of the film will join at the top of the space, thereby leaving a nearly planar film. Examples of CVD SiOj processes capable of the required high degree of conformality are ECR deposition and tetraethyl orthosilicate (TEOS) plasma CVD-enhanced. While this approach yields local planarization above closely spaced lines, the wide spaces between metal lines are not filled, and thus a sharp step is experienced at the edge of such spaces. Therefore, this approach is often coupled with SOG or resist etch-back processes or CMP.< >... 

Figure 2. Schematic diagram of various CVD techniques for diamond synthesis, (a) HFCVD (b) MW PACVD (c) ECR MW PACVD (d) DC PACVD (e) RF PACVD (0 DC thermal plasma CVD (g) RF thermal plasma CVD (h) flame (combustion) CVD.l (Reproduced with permission.)...

To lower the deposition temperature, CVD processes enhanced by plasma [48-58] and laser [55-58] have been investigated. Low-resistivity (< 40 pQ cm) TiN was deposited by Akahori et al. [59] using TiCL in an electron-cyclotron resonance (ECR) plasma process (Ts b = 540°C, microwave power = 2.8 kW). All films had stoichiometric composition with low chlorine concentrations of 0.16 at. % as determined by ICP-MS. This indicates that the nitridation reaction of TiCU is enhanced enormously by the ECR plasma. 

Deposition Bias sputter. Bias ECR, plasma chemical vapor deposition (CVD), RF plasma CVD Damage concern, too much dust... 

Plasmas can be used in CVD reactors to activate and partially decompose the precursor species and perhaps form new chemical species. This allows deposition at a temperature lower than thermal CVD. The process is called plasma-enhanced CVD (PECVD) (12). The plasmas are generated by direct-current, radio-frequency (r-f), or electron-cyclotron-resonance (ECR) techniques. Eigure 15 shows a parallel-plate CVD reactor that uses r-f power to generate the plasma. This type of PECVD reactor is in common use in the semiconductor industry to deposit siUcon nitride, Si N and glass (PSG) encapsulating layers a few micrometers-thick at deposition rates of 5—100 nm /min. 

Whereas a microwave plasma is most commonly used for the PE-CVD of diamond films, an ECR is the only plasma that is used for diamond deposition below 1 Torr [27-29]. Although Bozeman et al. [30] reported diamond deposition at 4 Torr with the use of a planar ICP, there have been a few reports that describe the synthesis of diamond by low-pressure ICP. Okada et al. [31-33] first reported the synthesis of nanocrystalline diamond particles in a low-pressure CH4/CO/H2 ICP, followed by Teii and Yoshida [34], with the same gas-phase chemistry. 

Figure 16 ECR (Electron Cyclotron Discharge) reactor for plasma-enhanced CVD (after Matsuo26).

Silicon nitride films deposited in para 11 el-pi ate, plasma-enhanced CVD reactors will be discussed in greater detail in a later chapter. However, they typically have a refractive index on the order of 2.0, partly because of hydrogen incorporated into the layer, and the ECR films appear similar. Also, as... 

Recognition of TiN as a supreb barrier to diffusional and electrical activity has resulted in extensive research on the CVD of TiN for microelectronic layers. Significant advances have been made in the area of plasma-assisted CVD where dc glow , ECR , and helicon plasmas have all been used. Implementation of such plasmas can reduce the processing temperature of reaction (b) to 400°C. For plasma deposition of TiN using titanium isopropoxide, the deposition temperature can be as low as 100°C, where the chemistry is outlined as follows ... 

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