Sputtering uniformity

Another important consideration for providing uniform implantation involves the geometry of the ion beam with respect to the target surface. Too high an angle from normal incidence leads to excessive sputtering and low retained dose. These issues and others pertinent to practical aspects of implantation treatment have been discussed (35,165). 

The simple d-c diode sputtering configuration has the advantage that (/) large areas can be sputtered rather uniformly over long periods of time (2) the target can be made conformal with the substrate (J) the target-to-substrate distance can be made smaU compared to thermal vaporization and (4) the... 

By examining the sputtered neutral particles (the majority channel) using nons-elective photoionization and TOFMS, SALI generates a relatively uniform sensitivity with semiquantitative raw data and overcomes many of the problems associated with SIMS. Estimates for sensitivities vary depending on the lateral spatial resolution for a commercial liquid-metal (Ga ) ion gun. Galculated values for SALI... 

The atom flux sputtered from a solid surface under energetic ion bombardment provides a representative sampling of the solid. Sputtered neutral mass spectrometry has been developed as method to quantitatively measure the composition of this atom flux and thus the composition of the sputtered material. The measurement of ionized sputtered neutrals has been a significant improvement over the use of sputtered ions as a measure of flux composition (the process called SIMS), since sputtered ion yields are seriously affected by matrix composition. Neutral panicles are ionized by a separate process after sputter atomization, and SNMS quantitation is thus independent of the matrix. Also, since the sputtering and ionization processes are separate, an ionization process can be selected that provides relatively uniform yields for essentially all elements. 

Platinum coatings may also be thermally sprayed or sputtered onto the titanium, to provide uniform well-bonded coatings. Titanium rod may also be spiral wound with platinum wire. However, the use of these techniques is limited. 

Metallization of semiconductor devices and replacement of evaporated or sputtered films to improve conformal uniformity.Pi... 

In devices with geometry below the 0.25 im level, titanium nitride will likely replace titanium-tungsten, since it has better barrier properties. The process of choice will likely be CVD, which offers improved uniformity and step coverage, although improvements in collimated sputtering may keep that process on line for a while. 

For comparison, a 20wt% Pt/XC72 catalysts prepared commercially by E-TEK had an average diameter of 2.6 nm. The sputter deposited Pt had a standard deviation between 0.42 and 0.49 nm, whereas the commercial E-TEK catalyst has a standard deviation of 0.79 nm. Thus, the sputtering technique creates smaller and more uniformly dispersed Pt particles than those prepared chemically. It should be noted that the Pt/C samples having low loadings prepared via sputtering did not uniformly coat... 

In the field of microelectronics, there is continuing research in developing new materials to be used in semiconductor fabrication. They must be formed as thin films in a controlled, reproducible and uniform manner to be useful in semiconductor manufacturing applications. Depth profiling by AES is used to assess the properties of such films. The samples are sputtered with an argon ion beam and analysis performed using standard sensitivity factors, and it is possible to demonstrate that such films are uniform throughout a depth of, say, 250 nm. 

Recent results were able to demonstrate that the coatings produced by electrodeposition display the same coherence and layer thickness uniformity as those of composition-modulated alloys produced by vacuum evaporation or sputter deposition. 

Injection molding requires the barrel temperature to be about 350°C with a barrel pressure in excess of 138 MPa. The mold is maintained at 110°C to ensure uniform flow and high definition, and to discourage an uneven index of refraction, birefringence. The CD is about four one-hundredths of an inch (0.5 mm) thick. For prerecorded CDs, the PC is compression-molded on a stamper imprinted with the recorder information. This takes about 4 sec. Once the clear piece of polycarbonate is formed, a thin, reflective aluminum layer is sputtered onto the disc. Then, a thin acrylic layer is sprayed over the aluminum to protect it. The label is then printed onto the acrylic surface and the CD is complete. This process is described later in greater detail. 

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