The influences of chromium and chromium oxide films and gas compositions on plasma etching characteristics were investigated. Oxygen as well as chlorine is found to be responsible for etching. One possible etching reaction is proposed, in which a basic reaction product is assumed to be CrO2Cl2 which will be volatile in gas plasma. The impurities such as W, Fe, and Cu contained in the film become nonvolatile compounds which accumulate on the surface of the film and form a masking layer resulting in a suppression of the reaction. Anomalous etching modes called the contour and reverse etches were found with the chromium oxide films containing tungsten impurities. The mechanism of these anomalous etching modes is discussed, in which the accumulation of the tungsten compounds on the surface of the film is a basic mechanism. The reverse etch mode was applied to the fabrication of photomasks for MOS LSI.

Abslraact. The calculauon of the torque T an a permanent ellipsoidal magnet immersed in a magnetic liquid is more delicate than one might be inclined to expect. This problem, for instance, has a bearing on fundamental discussions carried out in the past about the choice between different formulotioor of electromagnetic theory. The present paper analyses the calculation of T anew. emphasizing the relation to, and the explanation of. the imponmt experiment carded out by Whitwonh and Stopes-Roe in 1971. The outcome of the experiment is explained in r e m of stmdxd magnetastatics. based upon use of the scalar potential ). The relation to the sa-dled KennellySommerfeld eontmveny is commented upon. The physical interpretation of the situation is elucidated by -ing out in deml sn examination of the total energy balance in the special case of spherical mgnet geometry.

A computer program has been developed for the three-dimensional calculation of the absorbed energy density in polymer films on substrates in electron beam lithography. In this calculation the Monte Carlo results have been used for the radial energy intensity distribution for a point source electron beam. The program is based on the reciprocity principle proposed by Chang. Some exposure experiments have been conducted with an electron resist of PMMA (polymethyl methacrylate) for isolated patterns in the from of a line of finite length (8.1 µm) as well as of a rectangle (3.1×8.1 µm2) in order to check the reliability of the calculations. Operating beam voltages used for the investigation are 14 and 20 keV. The electron resist thickness is 8000 A. Relatively good agreement has been obtained between the calculated and the experimental results. This program is applicable to an arbitraty pattern, and therefore it will be useful for investigations of the proximity effect in electron beam lithography.

No abstract

SILANE PYROLYSISwas 6% and the level for u/u~f=6 was 10% at a bed temperature of 700~ aod a 65% silane concentration. However, care must be taken to avoid the use of gas velocities below the limit at which the reaction region spread out by the fluidizing gas will be too narrow. In this case, the resulting high reaction density causes undesirable bed aggregation. In an earlier study (6), the lower limit for gas velocity, expressed by the parameter U/Umf, was experimentally determined to be 3. The upper limit for velocity was reached when the bed slugged in an uncontrollable mode; this was found to be at U/Um~=8. ConclusionsKey operating guidelines for fluidized bed silicon production from silane have been defined. A scavenging mechanism has been proposed to account for the low fines elutriation in the temperature range of 600~176 Below 600~ the deposits are relatively poor arid loosely adhered to the particle surface. Above 800~ fines level starts to increase rapidly. Bed aggregation appears to be avoidable by keeping u/u~f>3. Beds have been operated at velocities as high as u/umf=8 without problems, such as excessive dust entrainment and erratic bed behavior.Based on the above empirical guidelines for temperature and fluidization velocity, the operating envelope for fluidized bed silane pyrolysis systems is thus identified as follows 600oc _50%) feed can be used with-663 out excessive fines generation if this set of operating conditions can be maintained. ABSTRACTSilicon nitride films were directly formed on silicon by plasma anodic nitridation within nitrogen and hydrogen. The nitridation pressure ranged from 0.5 to 2.0 torr, at temperatures from 700 ~ to 900~ The growth rate of silicon nitride increased with an increase of the dc bias voltage to the silicon wafers. The refractive index of the films was measured to be about 2.00-2.30 by ellipsometry. Film composition was analyzed with Auger electron spectroscopy. Dielectric breakdown strength of the silicon nitride films was about 6.0 MV/cm after oxygen heat-treatment.