the spin - on coatings , in accordance with the present invention , are prepared as shown in fig1 . a spin - on solution is applied to a substrate in step 101 . after application of the solution , the substrate is spun , in step 102 at a speed generally within the range from 500 to 7 , 000 rpm and depositing onto the center of the spinning substrate a suitable quantity of a spin - on solution . the materials generally employed for the amorphous coatings are silicon containing compounds including silanes , siloxanes , and silicon polymers which , upon thermal treatment , convert to silicon dioxide . many suitable commercially prepared materials are available such as the solution provided by allied chemical corporation of the morristown , n . j . under the trade designation accuglass , type 204 ; by owens - illinois company of toledo ohio , under the trade designation gr650 ; by futurrex , inc . of newton , n . j . under the designations of dc1 - 200 and dc4 - 500 ; and by filmtronics , inc . of butler , pa . under the trade designation sin . suitable silanes include tetramethoxy silane , and tetraethoxy silane . suitable siloxanes containing a silicon - oxygen backbone are disclosed in u . s . pat . no . 4 , 676 , 867 . in addition to those spin - on materials set forth above , tetraethoxy can be employed as a spin - on - glass material either by itself or in combination with other materials including the silicon containing materials previously mentioned . the spin - on materials are generally solvent solutions of the particular silicon containing material , the solvent in many instances being ethanol . other suitable solvents , such as methanol , propanol , butanol , methylethylketone , acetone and the like , can be used . the thickness of the spin - on layer is determined by the viscosity of the spin - on solution initially applied to the spinning substrate and the speed at which the substrate is spun . these variables must be chosen such that the resulting thickness of the spin - on layer is less than 1 micron , and , preferably , approximately 0 . 5 microns . after the spin - on application , the film of the substrate is preheated in step 103 at a suitable temperature depending on the composition of the spin - on solution . typical temperatures range from about 120 ° c . to about 350 ° c ., however temperatures in the range from 250 ° c . to 330 ° c . are recommended for some commercially available materials . the purpose of this preheat is to remove substantially all of the solvents by evaporation . next , the film is subjected to higher temperatures , in step 104 , in order to convert the coating to silicon dioxide when a silicon - containing solution is initially applied . typically , the temperatures in the conversion process are in the range 900 ° c . to 1100 ° c . the heating is done in the presence of a reducing atmosphere . under these conditions , a dense , high hardness is produced , the film containing a carbide component . the heating can be performed by an oven , infrared lights , a furnace , a hot plate , or a rapid thermal processor . the rapid thermal processor is available for such purposes and has the advantages of a rapid and controllable ramp up and cool down procedure , thermal uniformity through out the volume of the sample , environmental control , cleanliness , reproducibility , and safety . furthermore , thermal gradients in the film , solvent diffusion , and film recystalization phenomenon can be reduced or totally eliminated with the rapid thermal processor . by way of specific example , the rz 103 model rapid thermal processor distributed by aetaddex is suitable for purposes of the present invention . the aetaddex device is capable of curing spin - on coatings up to 1100 ° c . the substrate with the solid coating is preheated on a hot plate or oven to remove the solvent . the substrate together with the coating is ramped to 1100 ° c . from room temperature in one to three minutes . vacuum pumping cycles before and after processing may be employed to assure the quality of gas environment and safety of operation . processing gas flows at controlled rates during the processing period . half micron thick coatings are readily and reproducibly achieved with no peeling or observable cracks . after the heating step is completed , the substrate along with the spin - on coating is fabricated , in step 105 , into the appropriate element , e . g ., into magnetic thin film heads . the heating step can be carried out in the heating chamber by first vacuuming the heating chamber and then producing a reducing atmosphere in the heating chamber by flowing hydrogen gas along with a second gas through the heating chamber . operation of the present invention is believed to be apparent from the foregoing description and drawings , but a few words will be added for emphasis . the phase of the spin - on - glass in film fabrication in which the material is heated to convert the spin - on solution to near stoichiometric sio 2 at high temperatures ( i . e ., & gt ; 500 ° c .). the conversion is indicated by the refractive index value of 1 . 45 - 1 . 46 . and confirmed by esca analysis . however , when the process is performed in a reducing atmosphere , such as nitrogen or argon , a substantial amount of carbon is retained in the film and si - c is formed at high temperatures (≈ 900 ° c .- 1100 ° c .). this si - c formation is indicated by a discoloration of the amorphous film and the higher index of refraction (≈ 1 . 57 - 1 . 75 ). esca analysis indicates that a 5 %- 149 % in the carbon content of the film is found in a spin - on - glass film processed with a nitrogen atmosphere . the increase in the carbon content is directly related to the decrease in oxygen content of the film . therefore , performing the heating portion of the spin - on process in a nitrogen atmosphere at high temperature results in a mechanically superior film as compared to a film prepared in an air / oxygen atmosphere . in addition , the total stress of the spinon film appeared to be less than the stress of films processed in an air / o 2 atmosphere . the amorphous films processed in a nobel gas atmosphere , such as argon , also contain increased amounts of carbon as compared to films prepared in an air / o 2 atmosphere , but with less carbon than the films prepared in a nitrogen atmosphere . in addition , when the original spin - on solution included boron , then boron was found in the resulting film . the process of the present invention eliminates substrate surface pits which have a dimension less than 0 . 3 in size , a basic requirement for fabricating high yield magnetic recording heads . while the invention has been described with reference to a reducing atmosphere , such as nitrogen , and a nobel gas atmosphere , such as argon , it will be clear that the invention is easily adapted to other atmospheres having similar properties such as an ammonia or a methane gas atmosphere . while the invention has been described with particular reference to a preferred embodiment , it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements of the preferred embodiment without departing from invention . in addition , many modifications may be made to adapt a particular situation and material to a teaching of the invention without departing from the essential teachings of the present invention . as is evident from the foregoing description , certain aspects of the invention are not limited to the particular details of the examples illustrated , and it is therefore contemplated that other modifications and applications will occur to those skilled in the art . it is accordingly intended that the claims shall cover all such modifications and applications as do not depart from the true spirit and scope of the invention ,