The development of a dual rate technique for the growth of silicon-on-sapphire films

An experimental study of the effects of various parameters on the properties of (111) and (100)Si films grown on sapphire false(α‐Al2O3false) by the SiH4 pyrolysis CVD method has been carried out. The following were examined: autodoping, growth temperature and growth rate, As‐doped n‐type films, p‐type films doped with B, properties as a function of film thickness, and the effect of reactor configuration. It was determined that at growth rates of ∼2–6 μm/min in a vertical reactor n‐type (111) Si films grown at temperatures of 1050°–1100°C on Al2O3 substrates oriented near the (112̅0) plane are electrically superior to those grown on false(011̅2false)Al2O3 and false(101̅4false)Al2O3 over the temperature range 950°–1100°C. Films with electron mobilities as high as 600–700 cm2/V‐sec for carrier concentrations of 1016–1017 cm−3 were obtained. P‐type Si films grown using B2H6 as the dopant source were also electrically better on ∼false(11̅20false)Al2O3 [(111)Si‐growth] than on false(011̅2false)Al2O3 [(100)Si growth], Hall mobilities being ∼2–3 times larger for hole concentrations 1016– 1017 cm−3. A comparison of film properties of n‐type films as a function of thickness indicated both the (100) and (111)Si films behave essentially the same way, i.e., the average mobilities show a steady decrease with decreasing film thickness. These studies revealed the strong interrelationships that exist among the various parameters involved in optimizing Si growth on insulators and indicated that growth conditions (i) must be optimized for the particular substrate orientation chosen; (ii) differ for those substrate orientations which lead to the same Si orientation; (iii) are dependent on reactor geometry; and (iv) should be optimized for the particular film thickness desired.

Section: Effect Of Growth Rate On Film Properties--growthmentioning

confidence: 82%

The Preparation and Properties of (111)Si Films Grown on Sapphire by the SiH4 ‐ H 2 Process

Manasevit

Erdmann

Thorsen

1976

“…It is difficult to explain, however, why the n-channel device mobilities in the silicon on sapphire are lower than the Hall electron mobilities measured in equivalent films. It cannot be attributed to the effect of oxidation during device processing, since in general the Hall electron mobilities increase as the compensating aluminum autodoping is deactivated during thermal oxidation (17,23). In general, however, processing results in the degradation in the carrier mobility even in bulk silicon devices.…”

Section: Hall and Most Mobilities N ~- 1 • 101s/cms--inmentioning

confidence: 99%

“…Recently considerable effort has been directed toward minimizing the changes in the semiconducting properties in the heteroepitaxial silicon during thermal oxidation (3,22,23). Exposure to dry 02 for 1 hr at ll00~ has been taken as approximately equivalent to the thermal treatment employed during processing of the MOS transistor structures.…”

Section: Hall Mobilitiesmentioning

confidence: 99%

A Comparison of the Semiconducting Properties of Thin Films of Silicon on Sapphire and Spinel

Cullen

Corboy

1974

The Hall mobilities in 0.5 and 1.0 ~m thick heteroepitaxial silicon on (I[02) sapphire and (100) and (111) spinel substrates are compared. The substrates employed were Czochralski sapphire, alumina rich flame fusion spinel, stoichiometric Czochralski spinel, and a "modified" alumina-rich Czochralski spinel. The semiconducting properties of the silicon on the spinels are similar if the Czochralski grown substrate surfaces are air annealed prior to deposition. The reproducibility achieved in electrical properties in silicon on spinel is related to the method of preparation of the substrate. In comparing the semiconducting properties in silicon on sapphire with silicon on spinel, one finds that the MOS transistor mobilities are more similar than the Hall l-nobilities.

“…Once the surface and the sides of the wafers are completelv covered no more reactions such as [1] and [2] can occur because there is no further formation or transport of volatile suboxides. Different two-step growth techniques with a first high growth rate (for quickly covering the substrate) followed by a lower growth rate were established by several authors (12)(13)(14)(15).…”

mentioning

confidence: 99%

Optimization of the Deposition Conditions for Epitaxial Silicon Films on Czochralski Sapphire in the Silane‐Hydrogen System

Druminski

1980

The deposition of epitaxial silicon films on (1̅012) Czochralski sapphire from the silane/hydrogen system was investigated for growth temperatures from 880° to 980°C and for growth rates from 0.2 to 6.0 μm/min. The film quality was evaluated by optical absorption measurements. The temperature range, in which epitaxial film quality was obtained, shifts with increasing growth rates to higher deposition temperatures. This epitaxial temperature range is rather broad, e.g., 915°–965°C for 0.2–0.5 μm/min and 935°–985°C for 5.3–6.0 μm/min. A region for the optimum epitaxial deposition conditions, very suitable for MOS applications, is defined by the minimum values obtained from the optical absorption measurements. At temperatures below 915°C, decreasing crystalline quality was observed due to an increasing fraction of polycrystalline silicon. In addition the influence of the H2O content on the crystalline quality of the silicon films was investigated; for the production of a good epitaxial silicon film the H2O impurity fraction must be smaller than 1 ppm, especially in the low temperature region.