Plasma thickness

Figure C2.18.3. Relationship between ion-assisted etching and directionality in plasma etching, (a) Demonstration of the synergy between ion bombardment and reactive species during ion-assisted etching, (b) Ions incident on an etched feature. This situation prevails in glow discharges when the feature dimensions are much less than the plasma sheath thickness. Reproduced from [35]...

Solution polymerization of VDE in fluorinated and fluorochlorinated hydrocarbons such as CEC-113 and initiated with organic peroxides (99), especially bis(perfluoropropionyl) peroxide (100), has been claimed. Radiation-induced polymerization of VDE has also been investigated (101,102). Alkylboron compounds activated by oxygen initiate VDE polymerization in water or organic solvents (103,104). Microwave-stimulated, low pressure plasma polymerization of VDE gives polymer film that is <10 pm thick (105). Highly regular PVDE polymer with minimized defect stmcture was synthesized and claimed (106). Perdeuterated PVDE has also been prepared and described (107). 

Sihcon dioxide layers can be formed using any of several techniques, including thermal oxidation of siUcon, wet anodization, CVD, or plasma oxidation. Thermal oxidation is the dominant procedure used in IC fabrication. The oxidation process selected depends on the thickness and properties of the desired oxide layer. Thin oxides are formed in dry oxygen, whereas thick (>0.5 jim) oxide layers are formed in a water vapor atmosphere (13). 

Dielectric Film Deposition. Dielectric films are found in all VLSI circuits to provide insulation between conducting layers, as diffusion and ion implantation (qv) masks, for diffusion from doped oxides, to cap doped films to prevent outdiffusion, and for passivating devices as a measure of protection against external contamination, moisture, and scratches. Properties that define the nature and function of dielectric films are the dielectric constant, the process temperature, and specific fabrication characteristics such as step coverage, gap-filling capabihties, density stress, contamination, thickness uniformity, deposition rate, and moisture resistance (2). Several processes are used to deposit dielectric films including atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), or plasma-enhanced CVD (PECVD) (see Plasma technology). 

Fig. 4. Examples of emission spectrometry as a diagnostic monitoring tool for plasma processing, (a) The removal of chlorine contamination from copper diode leads using a hydrogen—nitrogen plasma. Emissions are added together from several wavelengths, (b) The etching and eventual removal of a 50-p.m thick polyimide layer from an aluminum substrate, where (x ) and (° ) correspond to wavelengths (519.82 and 561.02 nm, respectively) for molecular CO2...

Newer high velocity thermal spray coating processes produce coatings in compression rather than tension because of the shot peening effect of the supersonic particles on impact. This has permitted coating as thick as 12,500 p.m without delamination as compared to older processes limited to 1,250 p.m. The reduced residence time of particles at temperature minimises decomposition of carbides present in conventional d-c plasma. This improves wear and hardness (qv) properties. 

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. 

The pursuit of further miniaturization of electronic circuits has made submicrometer resolution Hthography a cmcial element in future computer engineering. LB films have long been considered potential candidates for resist appHcations, because conventional spin-coated photoresist materials have large pinhole densities and variations of thickness. In contrast, LB films are two-dimensional, layered, crystalline soHds that provide high control of film thickness and are impermeable to plasma down to a thickness of 40 nm (46). The electron beam polymerization of CO-tricosenoic acid monolayers has been mentioned. Another monomeric amphiphile used in an attempt to develop electron-beam-resist materials is a-octadecylacryUc acid (8). 

The gas around the arc plasma takes away a part of its heat by radiatioii. At high temperatures, the gas loses its specific gravity, becomes light weight and diminishes in momentum (< mv ). As a result, the gas is rendered incapable of penetrating through the arc plasma to quench it. The flow of gas through the thick of the arc plasma is thus impeded. 

A multilayer-type structure probably due to cords in the molten zone between single arc sprayed (0.25 MPa) Ni droplets and steel substrate were found in AES point depth profiles [2.158]. That particular arc spraying condition turned out to yield the best adhesion. Plasma-sprayed AI2O3 layers separated from pre-oxidized Ni Substrate had a micrometer-thick NiO layer on the substrate-sided face and micrometer-deep oxide interdiffusion [2.159]. In this work also, AES point depth profiling substantiated technological assumptions about adhesion mechanisms. 

Fig. 4.37. Depth (temporal) profile obtained on a multilayer coating produced by plasma vapor deposition (PVD) using optimized rf-glow discharge conditions. Layer thickness ...

Tsai et al. have used RAIR extensively in investigations of plasma polymerized acetylene films as primers for rubber-to-metal bonding [12]. Fig. 12 shows RAIR spectra of films having a thickness between about 5.7 and 90.0 nm. A strong band... 

Fig. 14. RAIR spectra of a plasma polymerized silica-like film deposited onto a polished aluminum substrate (A) before and (B) after annealing at ISO C for 30 min. Film thickness was about 735 A. Reprinted by permission of Gordon and Breach Science Publishers from Ref. [15].

The XPS survey spectrum of a 75 nm thick film of plasma polymerized acetylene that was deposited onto a polished steel substrate is shown in Fig. 18 [22]. This film consisted mostly of carbon and a small amount of oxygen. Thus, the main peaks in the spectrum were attributed to C(ls) electrons near 284.6 eV and 0(ls) electrons near 533.2 eV. Additional weak peaks due to X-ray-induced O(KVV) and C(KLL) Auger electrons were also observed. High-resolution C(ls) and 0(ls) spectra are shown in Fig. 19. The C(ls) peak was highly symmetric. 

Fig. 18. XPS survey spectrum of a plasma-polymerized acetylene film with a thickness of 75 nm that was deposited onto a polished steel substrate. Reproduced by ptermission of John Wiley and Sons from Ref. [22].

Cell membrane Roughly 50 50 lipid protein as a 5-um-thick The plasma membrane is a selectively... 

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