Very low voltage sputter coating

Echlin, Patrick; Gee, W. W. Haldane; Chapman, B. N.

doi:10.1111/j.1365-2818.1985.tb02573.x

Cited by 9 publications

(10 citation statements)

References 6 publications

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“…The fact that ion beam sputter coating produces finer grained thick platinum and gold films than diode sputter coating, and very fine grained tungsten films, has been well documented (Kanaya et al, 1974;Geller et al, 1979;Franks et al, 1980;Clay & Peace, 1981;Echlin et al, 1982). However, our low energy input diode sputter coated tungsten showed a significant improvement on other published work.…”

Section: Discussionsupporting

confidence: 63%

“…The cool nature of the technique was also clearly demonstrated by coating expanded polystyrene latex, a heat sensitive specimen, without damage. They did not assess the grain size or film structure but Echlin and co-workers have done so with 'low voltage' sputter coating (Echlin, 1981;Echlin et al, 1982). The grain size of nominally 10 or 15 nm thick films was reduced by deposition at low voltages but the sputtering rates achieved were considerably less than achieved by Robards et al (1981).…”

Section: Introductionmentioning

confidence: 99%

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Structure analysis of sputter‐coated and ion‐beam sputter‐coated films: a comparative study

Kemmenoe¹,

Bullock²

1983

Journal of Microscopy

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SUMMARY Gold, platinum and tungsten films were deposited by low energy input (7 mA, 450 V), or high deposition rate (80 mA, 1500 V), diode sputter coating and by ion beam sputter coating. Film structures on Formvar coated grids and on the surface of coated erythrocytes, resin embedded, sectioned, and recorded at high magnification in a TEM were compared using computer‐assisted measurements and analysis of film thickness and grain size. The average grain size of the thinnest gold and platinum films was relatively independent of the mode or rate of deposition but as the film thickness increased, significant differences in grain size and film structure were observed. Thick platinum or gold films deposited by low energy input sputter coating contained large grain size and electron transparent cracks; however, more even films with narrower cracks but larger grain size were produced at high deposition rates. Ion beam sputter coated gold had relatively large grain size in 10 nm thick films, but beyond this thickness the grains coalesced to form a continuous film. Platinum films deposited by ion beam sputter coating were even and free of electron transparent cracks and had a very small grain size (1–2 nm), which was relatively independent of the film thickness. Tungsten deposition either by low energy input or ion beam sputter coating resulted in fine grained even films which were free of electron transparent cracks. Such films remained granular in substructure and had a grain size of about 1 nm which was relatively independent of film thickness. Tungsten films produced at high deposition rates were of poorer quality. We conclude that thick diode sputter coated platinum and gold films are best deposited at high deposition rates provided the specimens are not heat sensitive, the improvement in film structure being more significant than the slight increase in grain size. Thick diode or ion beam sputter coated gold films should be suitable for low resolution SEM, and thin discontinuous gold films for medium resolution SEM. Diode sputter coated platinum should be suitable for medium resolution SEM and ion beam sputter coated platinum for medium and some high resolution SEM. 1–5 nm thick tungsten films, deposited by low energy input or ion beam sputter coating should be suitable for high resolution SEM, particularly where contrast is of less importance than resolution.

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Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Structure analysis of sputter‐coated and ion‐beam sputter‐coated films: a comparative study

Kemmenoe¹,

Bullock²

1983

Journal of Microscopy

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“…Although several authors have concluded that ion beam sputtering gives finer grained coatings than other sputtering methods (Geller et al, 1979;Franks et al, 1980;Clay and Peace, 1981;Evans and Franks, 1981;Echlin et al, 1982;Kemmenoe and Bullock, 19831, this conclusion is based upon studies in which the two types of sputtering were carried out under quite different conditions. Sputtering is a complex process, and in order to make comparisons, one must keep as many variables as possible constant when comparing different methods.…”

Section: Metal Coating For High Resolution Emmentioning

confidence: 87%

Preservation and visualization of molecular structure in detergent‐extracted whole mounts of cultured cells

Lindroth

Bell

Fredriksson

et al. 1992

Microscopy Res & Technique

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Today's electron microscopes have a resolution sufficient to resolve supramolecular structures. However, the methods used to prepare biological samples for electron microscopy often limit our ability to achieve the resolution that is theoretically possible. We use whole mounts of detergent-extracted cells grown on Formvar-coated gold grids as a model system to evaluate various steps in the preparation of biological samples for high resolution scanning electron microscopy (SEM). Factors that are important in determining the structure and composition of detergent-extracted cells include the nature of the detergent and the composition of the extraction vehicle. Chelation of calcium is extremely important to stabilize and preserve the cytoskeletal filaments. We have also demonstrated both morphologically and by gel electrophoresis that treatment of cells with bifunctional protein crosslinkers before or during extraction with detergent can significantly enhance the preservation of both proteins and supramolecular structures. The methods used to dry samples are a major determinant of the quality of structural preservation. For cytoskeletons freeze-drying (FD) is superior to critical point-drying (CPD), one reason being that CPD samples have to be dehydrated, thereby causing more shrinkage as compared to FD samples. The high pressures to which samples are exposed during CPD may also cause increased shrinkage, and water contamination during CPD causes severe structural damage. We have obtained the best structural preservation of detergent-extracted and fixed cells by manually plunging them into liquid propane and drying over night in a freeze-dryer. The factor that most limits achievement of high resolution in SEM is the metal coat, which has to be very thin, uniform, and free of grain in order not to hide structures or to create artifactual ones. We have found that sputter-coating with 1-3 nm of tungsten (W) or niobium (Nb) gives extremely fine-grained films as well as satisfactory emission of secondary electrons. These samples can also be examined at high resolution by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The best preservation and visualization of supramolecular structures have been obtained using cryosputtering, in which the samples are freeze-dried and then sputter-coated within the freeze-dryer while still frozen.

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“…Surprisingly, even such a thin layer proved sufficient to avoid charging artefacts on a large bulk sample. This may be due to: (i) fracture faces of frozen-hydrated samples are much flatter than surfaces of dried specimens, thus the coating layer is formed quite uniformly; (ii) due to the presence of water the electrical conductivity of a frozenhydrated specimen may be larger than after dehydration (Walther et al, 1990); (iii) the grain size of sputter-coated films becomes finer at lower specimen temperatures facilitating coalescence of the metal film (Echlin et al, 1985;Muller & Walther, 1989).…”

Section: Coating and Observation In Semmentioning

confidence: 99%

High‐resolution scanning electron microscopy of frozen‐hydrated and freeze‐substituted kidney tissue

Herter¹,

Tresp²,

Hentschel³

et al. 1991

Journal of Microscopy

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SUMMARY Inner surfaces and fracture faces of rabbit kidney tissue were investigated with high‐resolution scanning electron microscopy using two different cryopreparation techniques: (i) for the observation of fracture faces, cryofixed tissue was fractured and coated in a cryopreparation chamber dedicated to SEM, vacuum transferred onto a cold stage and observed in the frozen‐hydrated state; (ii) for the observation of inner surfaces of the nephron, water was removed after freezing and fracturing by freeze substitution and critical‐point drying of the tissue. By both methods, macromolecular structures such as intramembranous particles on fracture faces and particles on inner surfaces were imaged. The latter method was used to investigate in more detail surface structures of cells in the cortical collecting duct. These studies revealed a heterogeneity of intercalated cells not described thus far.

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Very low voltage sputter coating

Cited by 9 publications

References 6 publications

Structure analysis of sputter‐coated and ion‐beam sputter‐coated films: a comparative study

Structure analysis of sputter‐coated and ion‐beam sputter‐coated films: a comparative study

Preservation and visualization of molecular structure in detergent‐extracted whole mounts of cultured cells

High‐resolution scanning electron microscopy of frozen‐hydrated and freeze‐substituted kidney tissue

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