Kinetics of the chemical etching of c—Si surfaces in CC14CHC1a CH2C1 , and CH3C1 vapours induced by 20—ns pulses of the UV radiation of'Ar' and KrF excimer lasers is studied. The anomalous high rates of the solid surface etching more than 10 per pulse are realized. Non —thermal mechanisms of the UV photon enhancement of gas—surface reactions are discussed.

The activation processes kinetics has been considered for solids at laser resonance action within the semi classic approach1 The nonequilibrium function of particles distribution over the energy obtained has been used to calculate the energy averaged values and the probability of particles overcoming the potential barriers LTHE NON-EUILIBRIUMJUNCTIONS OF PARTICLES DISTRIBUTION A theoretical consideration of laser radiation interaction with a material is based as a rule on the appro ach accepted in quantum electronics1 In this case the radiation field is considered classical and the system where an interaction takes place a quantum onet1 The use of the for polyatomic molecules and condensed matter (multilevel quantum systems) is connected with considerable mathematical difficulties1 A description of various activation processes (diffusion formation of defects chemical reactions) in condensed media can be based on a classical approach1 In this case the states of atoms in solids are described with classical distribution functi ons1 So for example the Arreniusian dependence for the diffusion coefficient found experimentaly can be obtai ned by calculating particles flux (obeying the Maxwellian distribution) overcoming a potential barrier2. An ana logous approach can be used to describe the processes taking place under laser radiation considering that absor ption of laser radiation occurs by quanta whereas the system is described with the classical distribution func tion Let a particle system be characterized by the distribution function over energies F(E)1 The particles

Continuous wave laser microprocessing of diarrnd-1ike carbon films deposited on silicon is reported The conductive lines of 3-15 pm width with resistivity Lj . jo—2 ccm were formed into dielectric amcrphous film via its graphitization as evidenced by Rarnan spectroscopy. When the temperature within a laser spot rises up to 6000C the carbon oxidation starts, resulting in the film etching and the narrow channels formation The reflectivity in visible of the anneal ed DLC fi ims I s studied regarding them as a candidate for optical recording ridia.

Redistribution of optical radiation energy induced by dislocations and twins in transparent crystals is described. Several effects found experimentally are proposed for laser microtreatment applications. 1.

Stationary temperature fields existed on metal surface we studied in the case of heterogeneous exothermic reaction activation by two intensive inter fering beams. Analitical solution suitable for any variations of external pa rameters was obtained in the case of discontinuous temperature function for chemical thermal source. Realization conditions for stationary inhomogeneous distributions were found. Transitional modes responsible for bistability and hysteresis phenomena were investigated. '' Experimental possibilities of interf e rometric technique were analysed. 1 . THEORETICAL The study of macroscopic inhomogeneous effects in catalytic systems on the kinetics of chemical reactions is of immense interest for science and techno logy1. For this purpose vast possibilities are offered by the interferometric technique ensuring experimental reactivity modeling of a spatiallyperiodic surface energy source. With the existance of nonlinearities reaction exother mic effect in particular instabilities and dissipative structures can occur in the system. In the present paper the theoretical study is carried out for the behaviour of such a system with the discontinuous temperature function of the chemical heat source. For a one-dimensional system let two continuous-wave laser beams produce interference pattern with intensity q(1+pcoskx) on the surface of a thermally thin plate(catalyst). Here j. z is the percentage modulation k is the spatial frequency L is one halfperiod. The catalyst is exposed to ex ternal convection condition with heat extraction coefficient environment j$ temperature I . Metal absorbability is assumed to

The possibilities of phase relief thermochemical writing on the oxidazing metal surfaces have been theoretically investigated. For the purpose the thermal field formation induced by space modulated laser irradiation has been analyzed minimum relief space periods being estimated. The positive influence of the chemical reaction exothermicity on the thermal field contrast was shown in case of zero order reactions. The thermochemical writing of 6 irn spaced periodical structures was demonstrated. 1.

The process of AS and P layers formation on the substrate contacting with these elements organic solutions on the base of sol— vents like C6H6 and CS2 is investigated.

The CdTe and HgTe narrow-banth-gap seminconductor compounds and the solid solutions based on them (CdHg Te, 0.1 < x < 0.3) are promising materials for the manufacture of a number of semiconductor devices, such as IR radiation detectors, light-emitting diodes, and heterojunction lasers. This is precisely Ue eason why these materials have attracted widespread attention. At. present, laser radiation is being extensively used for altering the prope ties and structure of semiconductor layers. In this paper, we present the results of theoretical studies into the possibility of using lasei pulses to accele rat.e diffusion processes in structures the type of CdTe-CdHgTe.

Abstract not available.

Some aspects of photomodification of polymer glasses and their applicability for the tasks of Xray 1ithograph are discussed. 1. Modification of dielectrics in the fields smaller than the atomic ones results from the absorption of'' light which can be linear or nonjinear and which is always present in thermodynamically balanced systems. Whatever is taking place in the substance during this process is extremely complicated and multi form and is accompanied by the change In thermodynamical characteristics (compo-- sitlon temperature pressure). I)ue to this it is suitable to classify the processes by a thermodynamical parameter which basically determines the change in the substance properties. In low absorption media (at small intensity fluxes) the heating is negli gible and only a change in composition can take place as a result of photochein ical reactions. This modification can be called photochemical. . As the absorp-- tion centres accumulate or the intensity grows the thermal processes become essential. This is a thermochemical stage [l3J. At last this is characteris-- tic of solid matrix as a result of inhomogeneous heating and local change of volume the mechanochemical processes can be brought to the fore[lJ. This very classification will be used below in the study of the polymer modification. It is obvious that the results of the photomodification investigation can be used for creating optical technology in particular in submicron lithograph where polymers are widely used for

The application of reflectron time of flight mass spectrometry or analyzing the products of laser induced thin films modification and YBa2 Cu3 0 _ in bulk ablat ion is discussed . The measurements of threshol Xlaser fluences and fragment velocity distribution are presented.

One of the alldry microlithographic processes is considered which includes only two operat ions namely vacuum thermal evaporat ion of the res i st f i lm and subsequent patterning of the mask directly during exposure with laser radiation of A 266 nm. The mask patterning is performed on a projection lithography apparatus. Theoreticaland experimental results indicate that the proposed process permits formation of submicron features with high accuracy and relatively low requirements to the exposure dose control. 1 .

Under continuous COtlaser radiation an acceleration of admixture diffusion processes was observed. It has been shown that at laser radiation excitation of the oxygen system (01) in VzOs the anomalies of the diffusion processes kinetics depend on the character of phase transitions connected with oxygen vacancies1 1

Some physical ideas and imaginations about laser thermal activation of che mical reactions their influence on the condensed matter optical properties re discussed in this paperS Theoretical foundations of thermo chemical mecha n I sms o-f 1 aser beam i nteract i on wi th metal s are I ai d down The part i cul ar at tention is paid tothe questions of chemical reactions selfsupporting regimes initiation and the multiform of such regimes for oxidation is shown. 1.

There have been conducted researches for the presence of defects in specimens of repined carbonyl iron after the treatment by continuous radiation of C02-laser under subcritical conditions. High degree of presence of the defects is characterized by appearance of cellular dislocation structure and by considerable oversaturation of vacancies. There have been also investigated the conditions of realization of an accelerated diffusion of boron in iron and steels in treating by continuous radiation of CD2-- laser. It was revealed that the boron redistribution from the previously created layer of borides on the metal surface is accomplished in steels to the depthes of up to 3 mm. The accelerated oxygen diffusion stimulated by the laser radiation has been investigated on the basis of the obtained results of the process of internal oxidation of alloy Cu-Sn (0. 55 at 7. ). There has been proposed the model of process of accelerated transport. 2. FORMATION OF DEFECTS IN CARBONYL IRON UNDER CONTINUOUS LASER RADIATION The investigation of the defect formation under the continuous laser radiation 10. 6 sam) was conducted with the specimens (4x0. 8x80) mm of carbonyl iron 0. 008 C 0. 047 Mn Al + Si + S) refined in hydrogen atmosphere. The laser treatment was accomplished without flashing the metal surface. Treatment characteristics: radiation power P (0. 25-1. 1 kV. Specimen displacement speed under the laser beam V (10-2. 5) mm/s

The dynamics of Cd (cH ) 2 chemisorption and spontaneous decomposit ion on n-type 51(100) with native surface oxide the pathwa and efficiencies of the adsorbate desorption due to the absorption of the XeC1 laser radiation by silicon have been examined using laser-induced desorption miss spectrorrtry (LIDMS ) . The k inetics of these sur face processes has been found to depend on the preceding laser irradiation of the surface. The extremely fast chemisorption and efficient decomposition of the parent rrlecules have been observed on the irradiated silicon surface. The competition between intact dissociative and recombination desorption pathways was responsible for the observed laser fluence dependences of the desorption of Cd(CI-6) and i ts fragments. 1 . INTROOIJCTIct4 1 . 1 . Laser chemical vapour depos ition (LCVD). Laser-induced deposition of thin filme on solid surfaces by using volatile organometallic precursors has been the subject of numerous investigations in the 8Os2. Due to the spatial/temporal localization of laser radiation and the resonant nature of laser-rr1ecule interaction this deposition technique has such attractive features as submicrometer resolution of deposits high film growth rate and high quality lowtemperature processing. The deposition process can be controlled by varying the laser parameters (wavelength fluence beam spot on the substrate surface scanning speed ). A var iety of mater ials can be depos I ted using LCVD. Of special interest for microelectronics is the deposition of

The principle of a setup for realtime mass-spectrometry of gas phase reactions is described. An orifice between the high pressure (about 200 Pa) reaction cell and the quadrupol mass spectrometer reduces the pressure and controls some important performance parameter. . With this method it is also possible to investigate the kinetics of laser-induced gas/surface reactions. Some results for C02laser-induced reactions in the system SF6/Si are presented. 1.

New approach to the surface patterning is considered based on UV laser assisted decomposition of films of silicon organic compounds (SOC). Basic regimes of films processing are studied :the direct laser produced transformation of Soc into the silicon oxide, self— developing (ablating) as well as conventional UV laser lithography. Submicron structures of high quality silicon dioxide are realized

The new method of surface acoustic waves generation by moving laser beam is described. The maximum amplitude of the acoustic impulse 2000 nm was reached. 1 .

The present paper studies laser stimulation of high-temperature thermochemical processes. Pulse radiation or radiation of high—power OW—laser were used to stimulate diffusion processes in /1 , 2 and others!. Such an effect usually results in excitation of thermal degrees of freedom. We were interested only in the processes of pho tostirnulation and thus we used OW-lasers of low power which do not distort thermal dynamics of the processes. At the same time the radiation quantum energy was sufficient for an effective excitation of the electron subsystem of the sample where diffusion processes were studied.

Abstract not available.

A new laser methods and apparatus are reported for manufacturing of microoptical components with gradient refractions index. The physical model of the local laser modification of properties of glasslike materials is described. The main types of the MOC including high-aperture microlenses and microobjectives for optical communication integrated optical devices laser technique and technology and its specific parameters. 1.

The quantitative model of PHMA ablation is developed. The photochemical reactions heating of the polymer film and mechanical stresses are taken into consideration. The increasing of the optical absorption during the photochemical reaction caused by excimer laser is investigated. The developed model allowed to evalute the ablation parameters and to estimate the spatial resolution of this process. 1.

The update technology of integrated circuits (IC) imposes rigorous requirements on semiconductor substrates whose bulk and subsurface crystalline structures must be perfect. Of principal role here is the purity of the substrate surface. By the estimates, when producing very low size integration (VLSI) IC ( <105) , the output of acceptable pro-Vducts is as low as 5%. Half of the wastage is known to be due to contamination of the semiconductor wafer surfaces. It follws from the gained expirience that the majordifficulties of superhigh purificati— on are associated with removal of metal ions and submicron--size parti-'des from the semiconductor surface. A search of new purification tech— niques should concentrate on combating, first of ally these impurities. It is very desirable that purification run during technological proces— ses i.e. during the wafer washing, not considerably infringing the major technological course. The solution of the problem stimulates complex investigations of metal ions and dust particles of the sorptiondesorption processes in a heterogeneous semiconductor—liquid system. Let us consider some examples of laser action which may be used for semiconductor surface cleaning.

Forms of melting in the volume of NaCI single crystals induced by 100W CW carbon dioxide laser irradiation have been investigated. An ability of micronsize melt drops to wander across solid crystal as fast as 0. 11. 0mm/s is discovered. 1.

The growth of large area and directly patterned oxides on silicon using a variety of photon wavelengths is described. In particular the drive towards low temperature and high quality ultrathin layers will be emphasised. Towards this goal we show that U. V. photons initiate more efficient growth than does visible radiation. 1.

The laser beam is an interesting tool for production of thin surface layers. The energy input is locally limited thus leading to a snall heat loading of the substrate. The geometric dinensions of the coatings are small as compared to conventional thermal technics like surface melting and coating. In the following the multithin-layer technique is introduced. By this process coatings of small dimensions could be produced. Due to high processing speeds high cooling rates up to lO K/s are achieved by heat conduction into the substrate. This process results in fine microcrystalline structures of the deposit. Using NiCrBSi as coating material it will be shown how and to which extent different parameters influence structure and geometry of the coating. 2. MULTI-THIN-LAYER TECHNIQUE The multi-pass thin layer technique is in principle a powder feed process. Under an oblique angle a powder is blown by an inert gas stream into the laser beam. On their way to the surface the powder particles are partially heated. The surface itself is melted by the laser beam. So a good adherence is ensured between the molten surface and the impinging melting particles. This process can be repeated several times thus forming a coating by a multithinlayer technique see fig. 2. In principle the powder feed process is a well known " thick coating " process for conventional coatings like turbine blades dyes etc. /1/. In this however very small dimensions are desired which may be used for reasons of wear or corrosion resistance or for conductive or insolating layers in micro technics. In this work we investigated the influence of some processing parameters in order to achieve layers or traces of small geometries. 3. MULTIPLE THIN LAYER COATING OF NiCrBSi NiCrBSi had been used as a coating material to produce thin layers or traces. These alloys are hard and wear resistant materials which are usually applied by conventional powder spraying methods followed by arc- or flame-fusing of the sprayed layer. The main problem of conventional fusing is the high heat input of this process. Furtheron mixing of base material elements with the coating is disadvantageous. SPIE Vol. 1352 Laser Surface Microprocessing (1989) / 125

In the paper the results of a theoretical investigation of the growth process of laserplasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density substrate temperature) and film properties (thickness structure) . The results of some ex perimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical mo del. 1 .

Abstract not available.

The surface electromagnetic waves (SEW) focusing is considered on the basis of cylindrical SEW (CSEW) conceptionS The focusing features assotiated with borderinq media energy dissipation are discussed It is shown that thin tran. sitional layers existence can lead to the essential decreasing of focal spot dimensions. 1.

The question discussed in this paper are related to the formation of different dissipative structures on the surface of metals (vanadium) and the bulk of semiconductors (vanadium pentoxide). Two dimensional spatial structures of thermal field arised at laser light induced oxidation of metals in both upper and under surfaces are presented. The observed structures are explained in frames of theory of instabilities connected with temperature dependence of surface tension of melted material Benard and Rayleigh like convections due to temperature gradients caused by laser light. 1.

Growth kinetics of porous layers produced by gas-transfer controlled thermochemical reactions is described. The analysis of heat and mass-transfer problem allows to find the optimal regimes of laser treatment of solids. 1. GROWTH KINETICS OF SURFACE LAYERS The limiting role of gas transfer is characteristic of various processes in volved in the growth of solid layers of a new phase on the exposed surface'' in the course of laser oxidation and reduction of metals and laser synthesis and decomposition of nitrides and other compounds high-temperature superconductors included. When analyzing laser thermochemical reactions taking place in solids and involving the uptake or release of gases the absorbed energy flux q will be considered constant the thermooptical effects2 being disregarded. Let laser radiation incident on the surface of the original substance A give rise to a layer of a new phase B with a thickness of s through which a gas C migrates. We write the pertinent chemical decomposition and synthesis reactions in the form A 4 B + C and A + C ) B respectively. The direction of the reaction is determined by the sign of the Gibbs thermodynamic potential tG /H + TM where tH and tS are the changes of the enthalpy and entropy of the system respectively. According to the chemical equilibrium theory the pressure at the chemical reaction front is related to temperature by the Arrenius law:

Laser induced maskless etching has been applied to compound semiconductors and ceramics. Maximum etching rates ranging from 0. 1 tim/s to 850 tim/s with a minimum width of submicron depending on etching reaction were obtained. In-situ deposition and fluorescence were found to take place for thermochemical etching of compound semiconductors in CC14 atmospheres in which a minimum temperature rise necessary for etching reaction was clarified. Stoichiometry change and residual damage after etching were observed by microprobe photoluminescence and Raman scattering measurement. Laser chemical processing could for the first time be applied to magnetic head fabrication using Mn-Zn ferrite. 1.

Three different approaches to fast in situ processing of metal contacts are studied. The goal is to make high density interconnects with width, thickness and pitch respectively of the order of 10, 5 and 25 microns. The direct writing speed should be equal to or faster than 1 cm per second, while maintaining good electrical conductivity and surface adhesion of the metal stripes. The first approach is the classical laser chemical vapor deposition of copper from its bishexafluoroacetylacetonate (Cubishfa) precursor, which is pushed towards the practical limits of maximum writing speed. Seeding of the transparent glass-like substrates with layers of different metals and oxides which are extremely thin helps to increase the writing speed of this process significantly without substantially influencing the substrate's electrical properties. Writing speeds close to 1 cm l are attained. The second approach is to deposit metal from surface layers of metalorganic (MO) cluster compounds like Au55(P03)12Cl6 which have advantageous thermochemistry for the decomposition as well as a high metal content in the MO precursor. Such compounds can be decomposed with a laser to yield quite pure gold lines at speeds up to 10 cm s1. Such layers are also irradiated with ion and electron beams in an effort to try to make submicron metal contacts. The third approach consists of a fast in situ step in which the surface is locally prenucleated by decomposing an ultrathin MO layer with a photon or particle beam. In a second slow parallel processing step, a large number of prenucleated substrates are then "developed". The latter implies the selective metal deposition exclusively on top of the prenucleated stripes to create several micron thick metallic electrical contacts. We report on the selective metal deposition on ultrathin Pt prenucleation layers by electroless deposition from a copper sulfate bath, by decomposition from a copper formate solid surface layer, and by low pressure chemical vapor deposition from gaseous Cubishfa. Prenucleation was also tested with other metals.

Abstract not available.

The effects of electric current generation under laser irradiation of thin metallic films on randomlyrough and rippled dielectric substrates are discussed. Regular surface microrelief of substrate was produced by pulse laser processing of a polished dielectric. The determined laws of the current generation along the films their possible mechanisms and applications for varios types of pulse radiation detectors are described.

We report the synthesis of surface nitrides by multipulse XeC1 exciTaer laser irradiation in ambient NH3 atmosphere of metal (Ti Mo) and semiconductor (Si Ge) samples. The amount of nitride formed was shown to depend under various extents on the kind of sample the incident laser fluence and the number of subsequent laser pulses. The nitridation process is very sensitive to the oxygen presence. It was evidenced that only traces of oxygen were sufficient for promoting the formation of oxides and oxynitrides. 1.

New phenomena are observed theoretically in nonlinear optical responses of polydiacetylene-toluene sulfonate (PTS) irradiated by a strong laser beam. Within a two-level model of PTS the transient behavior of the induced susceptibility is investigated. Optical nutation is found and the optical Stark blue shift and bleaching are also found in qualitative agreement with experiments. In the steady state a new type of optical tristability mediated by phonons is found. A possible mechanism responsible for this tristability is discussed. 1 .

A review is given of the state of development of optical memory discs with emphasis on material aspects of the lightsensitive films currently evaluated and proposed for such media. Trends are delineated pointing at a class of materials which could help optical storage media in achieving their market po tential on the medium term. 1.

Lately a new film deposition technique — pulsed lase19 plasma vapour deposition (LPVD) — has been rather actively studied One of the main macroscopic features of any thin film deposition technique is distribution of film material on substrate. But this aspect of LPVD technique has been given a little attention. This paper discusses thickness profiles of the films deposited on the substrates by excimer laser plasma vapour deposition (ELPVD). Suggestions have been made concerning improvement of uniformity of the films thickness. Amorphous carbon films obtained by ELPVD technique can be used as protection and anti—reflection coatings for IR optics elements.

This work was aimed at studies into the basic physic—chemical processes govern ing the interaction between the Y203-4BaO-6CuO oxidefilm being deposited and the silicon substrate and the chemical stability of the Y Ba Cu 0 film on the surface 1 2 •3 7—x of S13N4 layer deposited on silicon.