Abstract:
An method for the formation of coating films on substrates which consists of a main high-temperature and high pressure drying chamber with two additional chambers located in front and behind the working chamber, respectively. The front drying chamber, which is installed between the loading station and the working chamber, is intended for drying the coating films at room temperature, while the rear drying chamber is intended for cooling after drying at high temperature and high pressure in the main working chamber. The front and rear chambers are provided with means for adjusting the respective drying and cooling processes by means of respective heating and cooling systems. This allows initial drying in a wider temperature range and final cooling under most optimum conditions.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of semiconductor lithography, in particular to a method and apparatus for coating a substrate with a polymer solution and for drying the applied coating. More specifically, the invention relates to the formation of photo-, electron-, and X-ray resists on the surfaces of semiconductor wafers. 
     BACKGROUND OF THE INVENTION 
     Resists are organic or inorganic materials which are applied either directly onto the surface of semiconductor substrate or onto the surface of a topological layer preformed on the substrate for the formation of a selected latent image of a pattern which later is turned into a functional layer of a chip to be produced. In a majority of cases, the materials applied on the semiconductor substrate are organic materials. There exist a great variety of such materials. Among them, tens of polymer compositions are commercially used as polymer-type resists. Types and properties of some of them are described, by Wayne M. Moreau in: “Semiconductor Lithography. Principles, Practices, and Materials”, Plenum Press, New York, London, 1988. 
     In the process of development of the latent image formed in the resist as a result of exposure to light or other radiant energy, the exposed or non-exposed areas are removed by subsequent etching processes to form the so called mask having a configuration of the aforementioned pattern. The aforementioned process is known as semiconductor lithography. The mask produced by the semiconductor lithography plays a crucially important role for protecting the masked areas during processing of opened areas in subsequent processes such as doping by ion implantation, coating in lift-off lithography, etching, etc. Films from which masks are formed are normally have a thickness within the range of from fractions of micron to several microns. 
     It is understood that protective property of the mask is one of the most important factors in the quality of the entire chip manufacturing process. 
     The properties of the mask, in turn, to a great extent depend on technological operations used in the manufacture of the masking film, such as application of a coating material on a substrate from a solution, uniform spreading of the applied material over the substrate, and drying of the applied coating for the formation of a coating film. 
     Quality of the masking films is determined by such factors as uniformity of thickness and properties, presence of defects such as pinholes, surface cracks, structural nonuniformity caused by foreign particles, etc., and adhesion. 
     It is understood that processes used for the manufacture of the mask should exclude formation of the aforementioned defects and combination with high adhesion of the film to the substrate. 
     It is obvious that a main process that determines the final quality of the mask is drying. In the context of the present invention, the term “drying” means removal of the solvent from the liquid polymer coating applied onto the surface of the substrate. It is understood that physical and chemical processes, which accompany removal of the solvent from resist also, may lead to conversions in the polymer itself. Such conversion, however, occur at temperatures higher than the temperature of drying. It should be noted in this connection, that the step of drying can be divided into a process of drying itself at a temperature that does not cause the aforementioned conversions and a process of baking at a temperature that is maintained to cause such conversion as hardening. 
     More specifically, drying out of a material includes the processes of penetration of the solvent from the polymer itself into free volumes in the polymer, such as voids, microcracks, or air bubbles with subsequent transition of the solvent from the liquid state into a vapor phase a gaseous phase (vapor). Kinetic characteristics (time behavior) of the above-indicated processes determine the mechanism of removal of the solvent from the coating. 
     The initial stage of drying, which is normally carried out at room temperatures, is characterized by a high content of the solvent in the polymer coating. As the coating becomes dry, the yield of the solvent into a gaseous phase is retarded, whereby the rate of drying is reduced. It is known, however, that by holding the polymer coating only at room temperatures, it is impossible to obtain high values of protective properties such as adhesion, defect-free condition, etc. 
     Therefore, for obtaining the above properties, drying should include a high-temperature stage (i.e., the stage at a temperature above room temperature but below the glass transition temperature for the polymer −T g . After completion of the phase separation at the first stage of drying with the formation of a polymer matrix that contains the solvent, the increase in the process temperature accelerates diffusion of the solvent into the polymer (as a rule, a constant of diffusion depends on the temperature exponentially). As a result, the solvent is rapidly removed from the polymer matrix. Increase in the polymer temperature also decreases its viscosity, which in addition to the aforementioned accelerated diffusion, leads to a decrease in internal stress. This, in turn, affects uniformity of adhesion over the coating area. It is understood, however, that the high-temperature stage of drying should not exceed the level at which such undesirable thermodestruction or thermopolymerization may occur. 
     It is known that the initial stage of drying of a polymer at an increased temperature is accompanied by a sharp increase in the rate of solvent removal. After having reached its maximum, this rate then drops to zero. 
     As has been mentioned above, evaporation of the solvent from the external surface of the coating occurs in parallel with a phase transition (evaporation) into free volumes of the polymer matrix, such as microcracks, voids, etc. This process is known as internal vapor formation. 
     It has been proven experimentally that connection exists between internal vapor formation and protective properties, for example, of a photoresist coating. Many factors influence kinetic characteristics of the process of the internal formation. The following are examples of these factors: concentration of the solvent in the polymer, solvent vapor pressure, geometry of microcavities, density of distribution of microcracks and microcavities in the coating volume, coefficient of diffusion of the solvent, viscosity and surface tension of the polymer coating, and temperature of the coating. 
     The increase in the rate of internal vapor formation leads to an increase in concentration of defects and to a decrease in adhesion of the coating to the substrate. These phenomena are caused by an increase in the gas pressure of solvent vapor in microcracks and microcavities and by subsequent opening of the aforementioned microcracks and microcavities to the interface between the substrate and the coating film and to the external surface of the film. 
     It is obvious that surface microcracks as well as microcavities and microcracks located near the surface of the coating film affect adhesive and protective properties of the coating film to a lesser degree than those located inside the film and on the interface between the coating and the substrate. It is understood that aggregation of such defects distributed across the film cross section may lead to the formation of pinholes in the coating film. 
     At the first stage of drying the internal vapor generation in the protective coating with a high concentration of the solvent does not essentially affects protective properties of the polymer coating. This is explained by favorable conditions for removal of the solvent at this stage of the drying, such as a relatively high rate of diffusion of the solvent molecules in the polymer film and high mobility of the polymer molecules enhancing closing of microcracks and microcavities. 
     Decrease in the concentration of he solvent is accompanied by an increase in the viscosity of the polymer in the coating film and decrease in planarization ability (as used herein the planarization ability is an ability of the polymer to create a flat surface and to heal irregularities of edges of the opened microcracks). 
     It should be noted that microcracks and microcavities in the coating film greatly vary in their shape and dimensions and that the smaller these defects, the better properties of the final coating. 
     The factor preventing the action of internal vapor formation and suppressing the propagation of gas microcracks is an excessive external pressure in combination with heating of the coating film. 
     An attempt has been made to improve properties of the coating film by a method comprising the steps of: retaining the polymer coating at room temperature for a time interval from 20 sec to 1 hour; heating of the coating at an increased pressure sufficient for suppressing propagation of microcracks into the coating and for deteriorating its properties; and cooling the treated coating. See an article by V. P. Lavrischev, V. A. Peremychtchev in: “Study of mechanism of removing the solvent from the photoresist film”, 1975 Electronics, issue 5 (53), pages 58-65). 
     However, the entire process was conducted in one and the same chamber, and this did not allow to eliminate the phenomenon of internal vapor formation. Therefore the method described above did not allow to produce a defect free product. Furthermore, this method does not ensure adequate adhesion of the coating film to the substrate, which shortens the service life of the polymer coating. Both drawbacks are initiated by the process of propagation of microcracks of the coating during its drying. This has been confirmed by experiments conducted with the use of an apparatus described in “Electronic industry” No. 5 (77), pages 50-52, 1979, Moscow, “Unit for forming photoresist coatings AFF-2”, by V. V. Anufrienko, V. I. Osnin, V. A. Peremychtchev, V. L. Sanderov, V. N. Tsarev. 
     The aforementioned apparatus has a sealed working chamber with a heater connected to a loading chamber via an air-tight damper on one side and to an unloading chamber via an air-tight damper on the other side. The working chamber can be connected via an appropriate shut-off valve system to a high-pressure main. 
     In such a device the excessive pressure is built up at the stage of holding the polymer coating at elevated temperatures. In this case, building-up of the excessive pressure in a high-temperature chamber is possible only after loading the substrate into the chamber and closing the loading hatch with an air-tight damper. A disadvantage of the aforementioned device is that the high pressure is released while the substrate is still hot and development of microdefects is still possible. 
     Furthermore, even an insignificant time shift between the high-pressure process and the high-temperature process may result in an instant reaction of the film to deviations in the drying conditions with the formation of the cracks. This is because the film is very thin and can be instantly overheated under normal pressure if the application of high pressure and high temperature are not synchronized. 
     U.S. Pat. No. 5,361,515 issued to Peremychtchev on Nov. 8, 1994 discloses a method and apparatus for drying the protective polymer coating applied onto the surface of a substrate article from solution. The process described in the aforementioned U.S. patent is characterized by the fact that at the drying stage of holding the coating at room temperature, the action of excessive pressure precedes the raise of temperature, while at the stage of cooling the temperature drop precedes the release of high pressure. 
     The apparatus of U.S. Pat. No. 5,361,515 differs from the apparatus described above by a provision of two additional drying chambers located in front and behind the working chamber respectively. The front drying chamber, which is installed between the loading chamber and the working chamber, is intended for drying the coating at room temperature, while rear drying chamber is intended for cooling after drying at high temperature and high pressure in the main working chamber. 
     A main disadvantage of the invention of U.S. Pat. No. 5,361,515 is that the front and rear chambers have limited functional capabilities. More specifically, the front drying chamber, which determined initial stage of drying, makes it possible to conduct initial drying only in a strictly specified temperature range of 18° C. to 28° C. However, films formed prior to transfer to the main high-temperature and high-pressure chamber under the indicated temperature range, may have meso- and macroscopic nonuniformities. This is because isolation of the phase with low content of the solvent may occur already in the initial drying stage in the front chamber. This means that the in the coating film transferred to the main chamber the solvent may already have a nonuniform distribution. In other words, the coating film will contain inclusion of a solid phase, i.e., inclusions of the phase, which is harder than the rest of the coating material. Such clusterization takes place during polymerization even in a liquid phase. 
     In subsequent drying under high temperature and high pressure the aforementioned solid phase inclusions will serve as sources of concentration of stress, impair adhesion, and form microcracks and microcavities around the nuclei of the stress. 
     It is known that the film formation process has a very complicated mechanism, which depends not only on the temperature of drying but also on variation of temperature in time. Therefore it is very important to control the initial drying process in time. However, the apparatus of U.S. Pat. No. 5,361,515 does not allow such control. 
     The stage of cooling in the rear chamber after release of pressure is carried out via a contact-type cooler which does not allow quick and combined modes of cooling which may be required for obtaining a high quality coatings free of internal stress and microdefects in combination with high adhesive properties of the coating film. 
     OBJECTS OF INVENTION 
     It is an object of the invention to provide a method and apparatus, which allow initial drying in a wide temperature range with controlled temperature variation mode in the drying stage. Another object is to provide method and apparatus which allow quick and combined modes of cooling of the coating film at the cooling stage after release of high temperature and high pressure. Still another object is to provide coating films, which are free of defects caused by internal stress and microcavities. 
     SUMMARY OF THE INVENTION 
     An apparatus of the invention is intended for the formation of coating films on substrates and consists of a main high-temperature and high pressure drying chamber with two additional chambers located in front and behind the working chamber respectively. The front drying chamber, which is installed between the loading station and the working chamber, is intended for drying the coating at room temperature, while the rear drying chamber is intended for cooling after drying at high temperature and high pressure in the main working chamber. The front and rear chambers are provided with means for adjusting the respective drying and cooling processes by means of respective heating and cooling systems. This allows initial drying in a wider temperature range and final cooling under most optimum conditions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side sectional view of a known apparatus for the formation of coating films on substrates with the drying under elevated pressure. 
     FIG. 2 is a side sectional view of an apparatus of the invention for the formation of coating films on substrates with an improved chambers for preliminary drying and a for post-drying cooling. 
     FIG. 3 is a graph illustrating an example of temperature variations during preliminary drying of the coating layer. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An apparatus of the invention for drying a polymer coating on a substrate is shown in FIGS. 2, which is a side sectional view of the apparatus. As can be seen from this drawing, similar to the prior art device, the apparatus of the invention consists of three major parts sequentially arranged one after another in the direction of process steps, i.e., a preliminary drying chamber  10 , a main high-pressure drying chamber  11 , and a post-drying cooling chamber  13 . 
     The preliminary drying chamber  10  is a sealed chamber, which has a loading hatch  12  with an air-tight damper  14  and an unloading hatch  16  with an air-tight damper  18 . Located inside the chamber  10  is a platform  20  for receiving semiconductor substrates (not shown) with a polymer coating, e.g., a semiconductor wafer with a resist coating in a liquid state, and a conveying mechanism  22  in the form of an endless belt for conveying the wafers from the loading hatch  12  to the unloading hatch  16 . 
     Located underneath the platform  20  is a preheater  24 , e.g., of an infrared type. This infrared preheater may comprise, e.g., quartz lamps having tungsten spiral heating elements and filled with krypton. The preheater is connected to an electric power supply unit  26  via electric feedthrough devices  28  and  30  and lead wires  32  and  34 . Such feedthrough devices are known in the art. 
     Located above the platform  20  is a precooler  36  in the form of a flat heat exchanger with dimensions exceeding the size of the water being treated. The precooler may comprise, e.g., a Peltier-type cooler which consists of a semiconductor plate  38  connected to a current supply unit  40  via electric feed through devices  42  and  44 . The heat generated by the semiconductor plate is removed by heat-exchanging tubes  46 , which are guided outside the chamber  10  via feedthrough devices (not shown). Peltier-type coolers are produced, e.g., by ThermoElectric Cooling America, Chicago Ill., USA. 
     The coolers of this type are characterized by instant cooling which is very important for controlling the preliminary drying process. 
     The current supply units  26  and  40  are connected to a controller  48  for simultaneous controlling operations of the preheater  24  and the precooler  36 . 
     The chamber  10  is connected via shut-off valves  50  and  52  with a high-pressure pipeline  54 . A branch  56  from the portion of the pipeline  54  located between the shut-off valves  50  and  52  has a shut-off valve  58  for connection to the atmosphere. 
     The preliminary drying chamber  10  is connected via the unloading hatch  16  to the main high-temperature high-pressure drying chamber  11 . 
     The high-temperature chamber  11  is a sealed chamber which is provided with a hatch  60  and an air-tight damper  62  for unloading the wafers into the post-drying cooling chamber  13 . Located inside the high-temperature chamber  11  is a platform  64  for receiving the wafers from the chamber  11  and a mechanism  66  in the form of an endless belt for conveying the wafers. The chamber  11  is connected with a high-pressure pipeline  54  through a pipe  68  with two shut-off valves  70  and  72 . The pipe  68  has a branch  74  between the shut-off valves  70  and  72 . The branch  74  has a shut-off valve  76  for connecting the pipe  68  to the atmosphere. 
     Located beneath the platform  64  is a heater  78 , which is connected via electric feedthrough devices  80  and  82  to a current supply unit (not shown). 
     Next in the direction of movement of the substrate in the technological process is the post-drying cooling chamber  13 . Similar to the chambers  10  and  11 , the chamber  13  is a sealed chamber that has a platform  84  with a wafer conveying means  86  in the form of an endless belt. The wafers are loaded onto the platform  84  via the hatch  60  and an air-tight damper  62  of the high-temperature high-pressure chamber  11 . The treated wafers are unloaded from the chamber  13  via a hatch  88  and an air-tight damper  90 . 
     Located beneath the platform  84  is a cooler  92 , e.g., of the same type as the Peltier cooler  36  of the chamber  10 . The feedthrough devices, power supply, and a controller of the cooler  36  are not shown as they are substantially the same as those associated with the cooler  36 . Similar to the chambers  10 , and  11 , the cooling chamber  13  is connected to the high-pressure pipeline  54  via a pipe  94  having two shut-off valves  96  and  98 . The pipe  94  has a branch  100  at a point between the shut-off valves  96  and  98  with a shut-off valve  102  for connecting the pipe  94  to the atmosphere. 
     Operation of the Apparatus of FIG. 2 
     The apparatus of the invention operates as follows: 
     Preliminarily, the high-temperature chamber  11  is prepared for operation. For this purpose, the air-tight dampers  18  and  62  are closed, the heater  78  is activated, the shut-off valves  70  and  72  of the high-pressure pipeline  54  are opened (the shut-off valve  76 , which connects the chamber  11  with the atmosphere, is closed for the entire cycle of drying of the polymer protective coating). 
     A substrate (not shown) with a liquid polymer coating on its upper surface is loaded into the preliminary drying chamber through the opened loading hatch  12  by means of the conveying belt  22  onto the platform  20 . The damper  14  of the hatch  12  is closed, and the shut-off valve  50  is opened while the shut-off valve  52  is opened (the shut-off valve  58  that connects the chamber  10  with the atmosphere, is closed). Under these condition, the preliminary drying cycle, i.e., the first temperature cycle, is initiated. The heater  24  and the cooler  36  are activated, and the controller  48  sets the temperature mode for the first temperature cycle. 
     The inventor has found that polymeric coatings may require different temperature modes of preliminary drying, which depend, e.g., on the type of the polymer and the type of a solvent in the coating. Therefore the temperatures required for the first temperature cycle may go beyond the range of 18° C. to 28° C., as specified by the U.S. Pat. No. 5,361,515. In other words, the temperature of first temperature cycle may be below 18° C. and higher than 28° C. Furthermore, some types of resists, e.g., Kodak KTFR negative photoresist (trademark of Eastman Kodak), or the like, in combination with a number of solvents, demonstrate the best results when the first temperature cycle is carried out at a temperature exceeding 30° C. Other resists may require complicated temperature modes with rapidly alternating cycles of heating and cooling to room temperature. An example of such alternating temperature modes is shown in FIG. 3, where time is plotted on the abscissa axis and the temperature is plotted on the ordinate axis. More specifically, the mode of the first temperature cycle in the chamber  10  may include several cycles of rapid heating to a temperature close to or even slightly exceeding (by several degrees) the glass transition point T g  and even the boiling point T b  of the solvent, in which the polymer is dissolved. Under this condition, the solvent is not transferred into a gaseous phase, but rather is turned into an overheated liquid, which has a very high mobility in the polymer matrix. As a result, the solvent is expelled from the inner layers of the coating film to the surface of the film without violation of the continuity of the coating film. 
     As shown in FIG. 3, the first temperature cycle in the chamber is started at atmospheric pressure and then, after a certain period of time, the shut-off valve  58  is closed, the shut-off valves  50  and  52  are opened, and hatch  18  is opened. As a result, the working gas is supplied under an elevated pressure to the chamber  10 , so that the pressure in this chamber rapidly increases (FIG.  3 ). This constitutes a first pressure cycle, i.e., the pressure cycle conducted in the preliminary drying chamber. 
     The final temperature of the wafer at this stage of drying is determined by the temperature mode which is set by the controller and is selected in a wide range, depending on the type of the polymer and solvent in the coating layer. An example of the temperature mode in the chamber  10  is shown in FIG. 3 as alternating heating and cooling cycles. It is understood that such a mode is given only as an example and that many other temperature modes are possible. 
     After the first temperature cycle, which is conducted in the chamber  10 , is accomplished, the wafer is transferred via the open hatch  16  onto the platform  64  of the chamber  11  by the conveyor belt  66 . Since the hatch  16  was open, the pressure in the chamber  11  is the same as in the chamber  10 . 
     The main drying cycle, i.e., the second temperature cycle, which is conducted in the high-temperature high-pressure chamber  11 , does not differ from that of the prior art device. More specifically, the wafer is retained in the chamber  11  at a predetermined temperature, which in general is higher than the temperature in the chamber  10  (FIG.  3 ), and under the same predetermined pressure selected so as to provide the most optimal conditions for the main drying cycle and for the formation of a high-quality coating layer free of defects. 
     After the wafer is transferred to the platform  64  of the high-temperature high-pressure chamber, the damper  18  may be closed for closing communication between the chambers  10  and  11 . However, since the shut-off valves  70  and  72  are open, and the shut-off valve  76  is closed, the chamber  11  remains connected to the high-pressure pipeline  54 , so that pressure in the chamber  11  remains high. As soon as the hatch  16  is closed, the shut-off valve  52  is closed, and the shut-off valve  58  is opened, whereby the pressured in the chamber  10  is released to the atmosphere. The hatch  12  can now be opened by opening the damper  14 , so that the next wafer can be loaded into the preliminary drying chamber  10 , and processing of the next wafer can be started while the first wafer is still in the high-temperature high-pressure cycle in the chamber  11 . The pressure cycle conducted in the chamber  11  is called the second pressure cycle. 
     When this high-temperature high-pressure cycle is close to completion, the shut-off valve  102  is closed and the shut-off valves  96  and  98  are opened. The damper  90  of the hatch  88  in the post-drying cooling chamber  13  is also closed. Upon completion of the second temperature cycle and the second pressure cycle in the chamber  11 , the pressure in the chambers  11  and  13  is the same, since both these chambers are connected to the high-pressure pipeline  54  via respective shut-off valves. Now the damper  62  of the hatch  60  can be opened, and the first wafer is transferred by the conveyor belt  66  to the conveyor belt  86  via the hatch  60  and is placed onto the platform  84  of the post-drying cooling chamber  13 . 
     Since the temperature of the platform  84  and of the entire environment in the chamber  13  is preset by the controller (not shown) and is lower than in the high-pressure high-temperature chamber  11 , the process of cooling of the first wafer is started at the moment when this wafer enters the chamber  13 . The cooling is carried out by means of the heat-exchange cooler  92 . During this cooling cycle the high-temperature high-pressure cycle can be started for the second wafer, and the first chamber  10  can be prepared for loading the third wafer. The third wafer is then loaded into the first chamber  10  after the hatch  60  is closed. When the cooling cycle in the chamber  13  is close to completion, the hatch  60  is closed by the damper  62 , and the pressure in the chamber  13  is dropped by closing the shut-off valve  98  and opening the shut-off valve  102 . The hatch  88  is then opened by raising the damper  90 , and the first wafer is unloaded from the apparatus as a final product. 
     The entire wafer treatment cycle is then repeated for the second wafer, which by that time could have been transferred to the platform  64  of the chamber  11 . 
     EXAMPLES 
     The method and the apparatus of the invention were tested experimentally by drying coating films prepared from photoresists of DQ-type produced by Elma Factory, Zelenograd, Russia and of FP-051SH type produced by NIOPIK, Dolgtoprudny, Russia. 
     The tests were aimed at studying dependence of adhesion on parameters of drying of the photolayer under pressure, in particular, on the temperature of the polymer coating in the low-temperature stage of the process prior to the high-temperature high-pressure cycle. 
     Types of photoresists chosen for the tests had different compositions including different solvents and different viscosities. 
     The polymers were applied onto a chromium-plated glass substrates by a centrifuge with the frequency of rotation that ensured thickness of the coating layer in the range of 1.0±0.05 μm. Subsequent drying was carried out on the apparatus of the invention. The test was carried out under the following temperature conditions: 
     22° C.—temperature of the environment (the heat exchanger is switched off); 
     14° C.—manufacturer-recommended storage temperature for DQ-photoresists; 
     30° C.—temperature at which rapid removal of the solvent from the photoresist is initiated. 
     Other temperature and pressure conditions were the same as in the method described in U.S. Pat. No. 5,361,515. The residence time of preliminary drying in the first chamber was 3 min. The residence time for high-temperature high-pressure drying in the second chamber at 100° C. was 15 min. The pressure was 0.8 MPa. Ten plates of photoresists of each type were tested. 
     A criterion of adhesive strength of the coating layer to the substrate was a condition of a 1 μm-wide control line produced in photoresist by photolithography. The adhesive strength was evaluated by immersing the test plates in a weak solution (06.%) of KOH and measuring the lifetime of the aforementioned line on the substrates. 
     The results of the test are given in a table below. 
     
       
         
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Temperature 
                 Number of plates (out of 10) that preserved 
               
               
                 Photoresist 
                 during 
                 the marking line 
               
               
                 (0.5 μm 
                 preliminary 
                 Treatment time (min) 
               
             
          
           
               
                 thickness) 
                 drying, ° C. 
                 20 
                 40 
                 60 
                 80 
                 100 
                 120 
               
               
                   
               
               
                 FP-617 
                 14 
                 10 
                 10 
                 9 
                 4 
                 2 
                 0 
               
               
                   
                 22 
                 10 
                 10 
                 10 
                 8 
                 5 
                 3 
               
               
                   
                 30 
                 10 
                 10 
                 10 
                 10  
                 9 
                 9 
               
               
                 FP-051SH 
                 14 
                 10 
                  9 
                 9 
                 9 
                 9 
                 8 
               
               
                   
                 22 
                 10 
                  7 
                 5 
                 1 
                 0 
                 — 
               
               
                   
                 30 
                 8 
                  5 
                 4 
                 0 
                 — 
                 — 
               
               
                   
               
             
          
         
       
     
     As can be seen from this table, the temperature during preliminary drying affects the adhesive strength. This dependence is different for different resists. It can also be seen that improved adhesion can be obtained by preliminary drying at temperatures beyond the limits specified by U.S. Pat. No. 5,361,515. 
     Thus, it has been shown that the present invention provides a method and apparatus, which allow initial drying in a wide temperature range with controlled temperature variation mode in the drying stage, and combined modes of cooling of the coating film at the cooling stage after release of high temperature and high pressure. The invention provides quick removal of the solvent at the initial drying stage without violating the continuity of the coating film and without defects caused by internal stress and microcavities. 
     Although the invention has been described with reference to a specific embodiment, it is understood that this embodiment should not be construed as limiting the application of the invention. Therefore any changes in the shapes, materials, and constructions are possible, provided these changes do not depart from the scope of the patent claims. For example, the temperature mode in the chamber  10  can be different from the one shown in FIG.  3 . The temperature in the chamber  10  can be raised to the level of temperature in the chamber  11  prior to initiation of the preliminary drying cycle in the chamber  10 . The shut-off valves  50 ,  62 ,  58 ,  70 ,  72 ,  76 ,  96 ,  98 ,  102  can be controlled automatically and in synchronism with opening and closing the hatches by means of respective dampers. The three chamber apparatus was shown as an example of the most productive process suitable for continuous treatment of large quantities of substrates. It is understood that the entire method can be carried out in a single chamber, e.g., in the first chamber. In this case, however, each next drying step can be initiated only after completion of the previous step.