METHOD OF AND DEVICE FOR REMOVING RESIST

Abstract: A method of and a device for removing resist, which are capable of significantly promoting resist removing action effected by resist removing liquid and of improving uniformity in resist removing action by resist removing liquid to an exceedingly high level by spouting a mixture of resist removing liquid and gas or by alternately spouting resist removing liquid and gas onto said resist.

Description: The present invention relates to a process and an apparatus for removing a resist which are applicable in microprocessing methods representatively such as photolithography. The process and the apparatus of the present invention for removing a resist are effective particularly in the production of an ink jet recording head. In the microprocessing methods such as photolithography and the like, there is used a resist comprising photosensitive resin or the like in order to form a minute pattern. (Said resist is often called "photoresist" since it has a photosensitivity, but it will be hereinafter referred to as "resist".) For instance, in the case of producing a semiconductor element, a resist is applied onto a base member such as wafer, and after the resultant being subjected to light exposure, a soluble portion of the resist is removed in the development step or the successive removing step. Resist removing methods in the prior art, include the spraying method wherein a resist removing liquid (which is usually called "developing solution" or "removing solution" in the field of photolithography, but in the following, it will be collectively referred to as "removing liquid") is sprayed onto a resist on a base member to thereby remove the resist from the base member, and the dipping method wherein a base member having a resist disposed thereon is dipped into removing liquid to thereby remove the resist on the base member. When required, a treatment for promoting the removal of the resist such as ultrasonic vibration treatment, heating treatment, stirring treatment, pressure circulating treatment, or the like is performed for the removing liquid. After the removal of the resist having been accomplished in this way, the base member is usually washed with the use of a rinsing liquid, followed by subjecting the washed base member to drying. These conventional resist removing methods, have problems as will be described below. The finer the pattern formed the more the period of time for removing the resist is prolonged. However, when a removing liquid having a high resist solubility is used in order to shorten this period of time, portions of the resist other than the portion thereof to be removed are often swelled to cause a bridge, meander, mutual leaning or trailing between adjacent resist patterns. In the worst case, said portions of the resist other than the portion thereof to be removed may be dissolved, wherein the resulting pattern becomes to be of a narrowed width. Thus, it is difficult to obtain a highly precise resist pattern of a desired size and shape. On the other hand, in the case where removal of the resist is carried out over a relatively long period of time using a removing liquid which is not so high in solubility, it is possible to form a minute pattern with a satisfactory precision. However, a considerably large amount of removing liquid is required in this case. In addition, occasionally residues of the resist occur particularly at the fine portions and resist portions, which were once removed return to adhere, resulting in negative influences to successive steps. These problems are inadequately resolved in the prior art even by employing the foregoing treatments for promoting the removal of the resist. Now, as one of the principal and effective methods for producing an ink jet recording head, there is a method in which removal of the resist is performed, which is described in U.S. Patent No. 4,657,631 or U.S. Patent No. 4,775,445 and which is schematically shown in FIG. 4(A) through FIG. 4(F). In this method, on a base member 40 shown in FIG. 4(A) having an energy generating body 41 capable of generating an energy to be utilized for discharging ink disposed thereon is disposed a layer 42 comprising, for example, a positive type photosensitive resin as shown in FIG. 4(B). Then, the photosensitive resin layer 42 is subjected to patterning exposure to form a latent image 43a shown in FIG. 4(C), which is corresponding to ink pathway, on the photosensitive resin layer 42. Thereafter, the photosensitive resin layer 42 is subjected to development, to thereby pattern the photosensitive resin layer 42 as shown in FIG. 4(D). Successively, a material 44 capable of forming a wall for ink pathway is applied to cover the patterned photosensitive resin layer 43 as shown in FIG. 4(E). Then, after the patterned photosensitive resin layer 43 being subjected to exposure, the photosensitive resin layer is removed to form ink pathways 46 as shown in FIG. 4(F). Simultaneously with this step or after this step, a throughhole 45 for supplying ink to the ink pathways 46 is formed. Numeral reference 46a denotes a discharging outlet, through which ink is to be discharged, in communication with the ink pathways 46. According to the method briefly explained above, there can be produced an ink jet recording head of a relatively high reliability. An ink jet recording device provided with such ink jet recording head is commercially available. Even for such ink jet recording device, there is a demand for further improving not only the recording speed but also the quality of an image recorded. An ink jet recording head capable of satisfying such demands is an ink jet recording head which is basically provided with numerous ink discharging outlets being arranged at a high density. high density. There is a tendency that as numerous discharging outlets are arranged at a higher density, the ink discharging characteristics of the discharging outlets as a whole are reduced possibly due to the step of removing the resist at the time of producing the ink jet recording head. The above matter is not serious in the case of a head provided with a relatively small number of discharging outlets being arranged at a relatively low density. However, the above matter can be important in the case where numerous discharging outlets are arranged at a high density. Particularly, it is serious in the case of a so-called full-line type ink jet recording head which is provided with numerous, for instance, some thousands discharging outlets being arranged at a high density along the entire width of the recording area of a member on which an image is to be recorded, in which numerous electrothermal converting bodies are arranged at a high density on a base member such that they correspond to said numerous discharging outlets. Thus, these various subjects relative to removal of the resist are significant at the time of performing removal of the resist in the production of an ink jet recording head. An embodiment of the present invention aims to alleviate some of the foregoing problems and to provide a resist removing process and an apparatus therefor which enable one to remove a resist in a short time, whereby providing a resist-free surface with an excellent cleanliness. An embodiment of the present invention aims to alleviate some problems relative to removal of the resist and to provide a resist removing process and an apparatus therefor which enable one to obtain a pattern with a high precision in size and shape. An embodiment of the present invention aims to provide a resist removing process and an apparatus therefor in which the consumption of a removing liquid is relatively small and no negative influence is afforded to other constituent members. The present inventor made researches and studies in order to attain the above aims. As a result, it was found that the foregoing spraying method, dipping method, and the method comprising one of these methods and treatment for promoting the removal resist are merely due to reactions based on mutual contact between the resist and the removing liquid. This situation is further apparent in the case of removing the resist in order to produce an ink jet recording head due to the high density at which numerous discharging outlets are arranged and the high precision required for the size and shape of each of the minute ink pathways in communication with the discharging outlets Such requirements of high precision cannot be satisfactorily attained mainly due to the foregoing problems relative to removal of the resist; and because of this, deterioration is liable to occur for the discharging characteristics of ink from the discharging outlets as a whole. It is considered that the foregoing problems relative to removal of the resist at the fine pathways occur not only in the developing step wherein the photosensitive resin layer is developed to pattern said layer but also in the removing step wherein the patterned photosensitive layer is removed from the ink pathways. The present inventor made further extensive studies based on the above findings, and as a result, discovered that the resist removing efficiency using removing liquid can be markedly enhanced while raising the uniformity of removal of the resist by the removing liquid to an extremely high level when a gas-liquid mixture composed of the removing liquid and a gas is jetted onto the resist or the removing liquid and said gas are alternately jetted onto the resist. The present inventor performed removal of the resist on the basis of the knowledge thus obtained. As a result, removal of the resist could be effectively accomplished within a short period of time, wherein the cleanliness of the face after the resist having been removed therefrom was superior to that in the prior art. And a pattern with a markedly high precision in size and shape could be formed. The present inventor then applied the foregoing knowledge in the production of an ink jet recording head. As a result, an ink jet recording head provided with ink pathways of a markedly high precision in size and shape could be obtained. The present inventor set the ink jet recording head thus obtained to an apparatus main body and recording was performed by discharging ink therefrom. As a result, it was found that the ink jet recording head obtained in the above excels in ink discharging characteristics as a whole. The present invention has been accomplished as a result of further studies based on the findings thus obtained. The present invention is defined in the claims appended hereto. EP-A-0443796, which was not published at the priority date of the present application, describes a method of developing a resist pattern in which gas is jetted on to a developing surface during or after development. Incidentally, it is mentioned that Patent Abstract of Japan, vol.14, No. 526 (C-0779), and JP-A-2218481, describe a cleaning apparatus and a cleaning process in which a washing solution and air are applied via separate jet nozzles onto the surface of an object immersed in the washing solution, to achieve more effective and faster cleaning. The method described below can be desirably employed particularly in the case of removing the resist in order to produce an ink jet recording head. The present invention is the most advantageous in the case where the ink jet recording head is of full-line type. BRIEF EXPLANATION OF THE DRAWINGS In the accompanying drawings: FIG. 1 is a schematic diagram of resist removing apparatus that does not fall within the scope of the claims FIG. 2 is a schematic top view illustrating an example of a photomask; FIG. 3 is a schematic diagram of the resist removing apparatus according to the present invention; FIG. 4(A) through FIG. 4(F) are schematic slant views for explaining an application example of producing an ink jet recording head by employing the resist removing process according to the present invention; FIG. 5 is a schematic slant view illustrating the principal part of an ink jet recording apparatus; and FIG. 6 is a schematic slant view illustrating the outline of an ink jet recording apparatus in which a full-line type ink jet recording head is installed. An example of a resist removing appartus will now be described for the purpose of reference. In FIG. 1, numeral reference 1 stands for a removal vessel in which a resist removing liquid 1a is stored. In the inside of the removal vessel 1, there is disposed a fixing table 3 for fixing a base member 2 from which a resist is to be removed within the removing liquid 1a. The removal vessel 1 is provided with a liquid outlet 5 through which the removing liquid 1a is circulated to recycle. A conduit 8a is connected to the liquid outlet 5, and the conduit is provided with a filter 6 serving to remove foreign matters such as dust from the removing liquid 1a, a pump 7 serving to circulate the removing liquid 1a and to jet it through a jetting nozzle 4, and a first valve 8 serving to maintain or disconnect the connection of the conduit 8a. A conduit 9a is connected to a gas reservoir 10 through a gas inlet 11, and the conduit 9a is provided with a second valve 9 serving to continue or disconnect the connection thereof. Numeral reference 14 stands for a control system serving to control the opening and closing of each of the first valve 8 and the second valve 9. The present invention will be explained with reference to FIG. 3. In FIG. 3, the constituent portions which are the same as those of the resist removing apparatus of FIG. 1 are identified by the same numeral references as used in FIG. 1. In the following, explanation of these constituent portions will be omitted. The point by which this apparatus is distinguished from the resist removing apparatus of FIG. 1 is that the removal vessel 1 is structured such that the inside thereof is substantially enclosed to form a vacuum space and that a vacuum pump 13 is connected to the vacuum space. The inside of the removal vessel 1 can be brought to reduced pressure by actuating the vacuum pump 13. The example above explained with reference to FIG. 1 is performed under atmospheric pressure, but a pronounced effect is provided when it is performed under the condition of reduced pressure. That is, the improved effects of the present invention are provided by jetting the removing liquid and the gas in the form of a gas-liquid mixture to the resist maintained under reduced pressure or by alternately jetting the removing liquid and the gas to the resist maintained under reduced pressure. In order to maintain the resist under reduced pressure, the base member having the resist thereon to be removed is, for example, immersed in the removing liquid and the space to which the liquid face of the removing liquid faces is evacuated to reduced pressure by means of the pump. To maintain the resist under reduced pressure means that at least the circumferential region of the resist is maintained in the state of a reduced pressure. The term reduced pressure herein means a pressure lower than the atmospheric pressure, and it includes the case of a reduced pressure brought to a vacuumed state. The pressure of the space, which is in a reduced pressure state, to which the liquid face of the removing liquid faces should be properly determined depending upon related conditions such as the kind of the resist, the size of the resist, and the like, but it is desired to be 400 mmHg or less in practical view point. The apparatus explained with reference to FIG. 3 provides further improved effects when, other than the case of performing it continuously under constant reduced pressure, it is performed while periodically changing the pressure in a reduced pressure state. This is effective particularly in the case where the resist is of a complicated structure which is difficult to be removed, for instance, when the width of the pattern itself to be formed is small or when the space between the adjacent patterns is small. The embodiment above described is desirably applicable in the case of removing the resist in order to produce an ink jet recording head. Particularly, it is desirably applicable in the developing step shown in FIG. 4(D) wherein the photosensitive resin layer is developed and patterned and in the removing step shown in FIG. 4(F) wherein the patterned photosensitive resin layer is removed from the ink pathways. The embodiment above described is most advantageously applicable in the case of producing an ink jet recording head of full-line type. Further in addition, the embodiment above described is extremely effective when it is applied particularly in the removing step of performing removal of the resist in order to produce an ink jet recording head of the type wherein ink is discharged utilizing film boiling at ink caused by the action of thermal energy generated by the electrothermal converting body. The reason for this is considered that since not only the removing liquid but also the gas pass while being in contact with the ink pathways at the time of performing removal of the resist, a socalled aging effect is provided, for example, to the boiling face of the electrothermal converting body which causes said film boiling. The resist to be used in the embodiment above described can include photosensitive resins to be usually used in the field of photolithography. In the case of applying the embodiment above described in the production of an ink jet recording head, the resist is desired to be comprised of such a photosensitive resin layer of positive type as shown in FIG. 4(B). The positive type photosensitive resin is a resin material the solubility of which to solvents being increased upon irradiation of light thereto, and because of this, the removing step wherein the resist is removed by way of extracting it from the fine ink pathways as shown in FIG. 4(F) is made such that it can be more easily performed. Specific examples of such positive type photosensitive resin are materials comprising o-naphthoquinones and alkali-soluble phenol resins, materials comprising benzenediazoniums and alkali-soluble resins, and the like. Among these, a sheet made of, for example, a positive type photosensitive resin placed on a sheet comprising polyester (commercially available under the trademark of OZATEC R225, product by Hoechst Japan Kabushiki Kaisha) can be mentioned as the most appropriate ones in view of ease in handling. The removing liquid used in the above embodiment can include conventional removing liquids which are usually used in the field of photolithography. Specific examples of such removing liquid are aqueous solutions containing alkalies such as sodium hydroxide or potassium hydroxide, aqueous solutions containing acids such as hydrochloric acid or nitric acid, and organic solvents such as acetone, isopropyl alcohol or trichloroethane. The gas used in the above embodiment can include gases which are not reactive with any of the removing liquid and the resist, and gases which are reactive with either the removing liquid or the resist but do not hinder removal of the resist. Specific examples of such gas are inert gases such as He, Ne or Ar, and nitrogen gas. The effects of the present invention are provided in the case where the gas is used in a relatively small amount. However, it is practically desired for the volume ratio of the removing liquid to the gas to be in the range of 1 : 100 to 100 : 1. As for the jetting pressure at the jetting nozzle, it is desired to be in the range of 0.001 kg/cm 2 to 10 kg/cm 2 . In the case of performing the developing step in order to form patterns corresponding to the fine ink pathways as shown in FIG. 4(D) or in the case of performing the removing step in order to extract the resist from the fine ink pathways thereby removing the resist as shown in FIG. 4(F) respectively, removal of the resist is desired to be performed under the condition that the object to be head is arranged such that jetting is conducted from the throughhole side to the discharging outlet side. In the foregoing the jetting nozzle in a preferred embodiment is designed for together use for both the removing liquid and the gas. However in the present invention, the jetting nozzle can be designed to have a plurality of independent nozzles, one for the removing liquid only and the other for the gas only, as long as jetting to the resist can be performed in the way as above described. Further as above described, to recycle the removing liquid is desired in order to prevent wasteful consumption of the removing liquid, but it is possible to design the pathway of the removing liquid such that the removing liquid is not recycled as well as the pathway of the gas. Further in addition, in order to control the pressure or the flow rate, the conduit for the removing liquid or the gas may be additionally provided with appropriate equipments such as valves. The foregoing encountered portion of the two conduits may comprise a simple connection of the conduits or an independent gas mixing vessel. Explanation will be made of an example of an ink jet recording apparatus having an ink jet recording head therein which has been produced utilizing the foregoing embodiment, while referring to FIG. 5. FIG. 5 is a schematic slant view illustrating the principal part of an embodiment of the liquid jet recording apparatus. In FIG. 5, numeral reference 320 stands for a detachable cartridge type liquid jet recording head to which a recording liquid reservoir being integrated and which is provided with a plurality of ink discharging outlets opposite the recording face of a recording sheet (not shown in the figure) transported on a platen 324. Numeral reference 316 stands for a carriage for holding the ink jet recording head 320 thereon. The carriage is connected to part of a driving belt 318 which serves to transmit a driving force from a driving motor 317, and it is designed such that it can move while sliding through a pair of guide shafts 329A and 329B being arranged in parallel with each other. By this, the ink jet recording head 320 is made capable of moving back and forth along the entire width of the recording sheet. Numeral reference 326 stands for a recovery device which serves to recover a defect in ink discharging from the ink jet recording head 320 or to prevent occurrence of such defect, and it is disposed at a predetermined position within the range in which the ink jet recording head 320 is moved, specifically, for example, at a position opposite the home position. The recovery device 326 performs capping to the discharging outlets of the ink jet recording head 320 by a driving force through a driving mechanism 323 from a motor 322. In connection with the capping performance to the discharging outlets of the liquid jet recording head 320 by means of a cap 326A of the recovery device 326, there is performed suction of ink from the discharging outlets by means of an appropriate suction means (not shown in the figure) mounted to the recovery device 326 or force feed of ink by means of an appropriate pressure means (not shown in the figure) mounted to the ink supply path of the ink jet recording head. By this, ink is forced to expel through the discharging outlets to thereby conduct recovery treatment including removal of foreign materials such as viscid ink material present in the inside of each of the discharging outlets. Numeral reference 330 stands for a blade made of silicone rubber capable of serving as a wiping member which is disposed at a side face of the recovery device 326. The blade 330 is held at a blade holding member 330A in the form of a cantilever boom, and it is operated, as well as in the case of the recovery device 326, by means of the motor 322 and the driving mechanism 323 so as to encounter the outlet face of each of the discharging outlets of the ink jet recording head 320. By this, the blade 330 is projected in the range in which the ink jet recording head 320 is moved on appropriate timing during recording operation by the ink jet recording head 320 or after recovery treatment by using the recovery device 326, whereby dew drops, moisture, dusts or the like adhered on the outlet face of each of the discharging outlets of the ink jet recording head 320 can be swabbed. In this ink jet recording apparatus, drive of each of the recording sheet transportation means, the carriage and the recovery device, and drive of the recording head, and the like are controlled based on a demand or signal outputted from a control means containing a CPU disposed on the apparatus body side. FIG. 6 is a schematic slant view illustrating a rough diagram of an ink jet recording apparatus in which a full-line type ink jet recording head 32 is installed. In this figure, numeral reference 65 stands for a transportation belt which serves to transport a member on which record is to be made such as paper. The transportation of a member on which record is to be made (not shown in the figure) by the transportation belt 65 is performed upon revolution of a transportation roller 64. The lower face of the ink jet recording head 32 is so designed as to form a discharging outlet face 31 at which a plurality of discharging outlets being arranged so as to correspond to the entire width of the recording area of the member on which record is to be made. Example 1 A positive type photosensitive resin film (commercially available under the trademark of OZATEC R225, product by Hoechst Japan Kabushiki Kaisha) was used as the resist, and it was laminated on a glass base member at 100 °C and at a pressure of 3 kg/cm 2 . Then, using the photomask 20 shown in FIG. 2, pattern exposure was performed to the resist at 300 mJ/cm 2 by means of a high pressure mercury lamp to thereby form a pattern latent image of 20 µm in line width thereon. Then, the resist was subjected to heat treatment at 110 °C for 10 minutes. Thereafter, the base member having the resist thereon was fixed to the fixing table 3 of the resist removing apparatus shown in FIG. 3. A 3% NaOH aqueous solution was used as the removing liquid (developing solution), and the circulating flow rate by means of the pump 7 was made to be 2 ℓ/minute. As the gas, nitrogen gas was used. The inside of the removal vessel 1 was brought to a reduced pressure of 10 mmHg by means of the pump 13. Under this state, the removing liquid (developing solution) and the nitrogen gas were mixed at a volume ratio of 1 : 1, and the gas-liquid mixture was jetted to the resist at a jetting pressure of 1 kg/cm 2 to thereby perform development. Successively, the resultant was rinsed with pure water, followed by drying. In this example, the above treatments were performed for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 1, in which the development period of time is the mean value among the ten samples. As Table 1 illustrates, it was found that to remove the resist could have been accomplished within a shortened period of time without the non-exposed portion being swelled or dissolved and without occurrence of stain in this example. Example 2 The procedures of Example 1 were repeated, except for performing the development by alternately jetting the removing liquid (developing solution) and the nitrogen gas to the resist at an interval of 1 second and at a jetting pressure of 1 kg/cm 2 . In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 1, in which the development period of time is the mean value among the ten samples. Excellent results were obtained also in this example. Example 3 A positive type photosensitive resin (commercially available under the trademark of OFPR 800, product by Tokyo Ohkakohgyo Kabushiki Kaisha) was used as the resist, and it was applied to provide a film thickness of 1.3 µm by means of a roll coater, followed by prebaking at 90 °C for 30 minutes. Then, using the photomask 20 shown in FIG. 2, pattern exposure was performed to the resist at 5000 mJ/cm 2 to thereby form a pattern latent image of 20 µm in line width thereon. Using a spray developing machine (product by Izumiseisakusho Kabushiki Kaisha), NMD-3 (trademark name, product by Tokyo Ohkakohgyo Kabushiki Kaisha) was sprayed at a pressure of 0.2 kg/cm 2 to thereby perform development. Then, the resultant was rinsed with pure water, followed by drying. In order to improve the adhesion of the resist to the base member, postbaking was performed at 120 °C for 30 minutes. Thereafter, the base member having the resist thereon was fixed to the fixing table 3 of the resist removing apparatus shown in FIG. 3. A removing liquid 1165 (trademark name, product by Shipley Company) was used as the removing liquid (removing liquid), and the circulating flow rate by means of the pump 7 was made to be 2 ℓ/minute. As the gas, nitrogen gas was used. The inside of the removal vessel 1 was brought to a reduced pressure of 10 mmHg by means of the pump 13. Under this state, the removing liquid (removing liquid) and the nitrogen gas were mixed at a volume ratio of 1 : 1, and the gas-liquid mixture was jetted to the resist at a jetting pressure of 1.5 kg/cm 2 to thereby perform removal of the resist. Successively, the resultant was rinsed with pure water, followed by drying. In this example, the above treatments were performed for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 2, in which the removal period of time is the mean value among the ten samples. As Table 2 illustrates, it was found that to remove the resist could have been accomplished within a shortened period of time without occurrence of stain in this example. Example 4 The procedures of Example 3 were repeated, except for performing the removal of the resist by alternately jetting the removing liquid (removing liquid) and the nitrogen gas to the resist at an interval of 1 second and at a jetting pressure of 1.5 kg/cm 2 . In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 2, in which the removing period of time is the mean value among the ten samples. Excellent results were obtained also in this example. Example 5 The procedures of Example 1 were repeated, except for continuously changing the inner pressure of the removal vessel 1 in the developing step between 10 mmHg and 50 mmHg at a periodical cycle of one minute. In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined. As a result, excellent results were obtained also in this example. Example 6 The procedures of Example 3 were repeated, except for continuously changing the inner pressure of the removal vessel 1 in the removing step between 10 mmHg and 50 mmHg at a periodical cycle of one minute. In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined. As a result, excellent results were obtained also in this example. Comparative Example 1 The procedures of Example 1 were repeated, except that the gas was not used and only the removing liquid (developing solution) was jetted to the resist at a jetting pressure of 1 kg/cm 2 to thereby perform development. In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 1, in which the development period of time is the mean value among the ten samples. Comparative Example 2 The procedures of Example 1 were repeated, except that using a spray developing machine (product by Izumiseisakusho Kabushiki Kaisha), the removing liquid (developing solution) was sprayed to the resist at a jetting pressure of 1 kg/cm 2 to thereby perform development. In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 1, in which the development period of time is the mean value among the ten samples. Comparative Example 3 The procedures of Example 3 were repeated, except that the gas was not used and only the removing liquid (removing liquid) was jetted to the resist at a jetting pressure of 1.5 kg/cm 2 to thereby perform the removal of the resist. In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 2, in which the removing period of time is the mean value among the ten samples. Comparative Example 4 The procedures of Example 3 were repeated, except that using a spray developing machine (product by Izumiseisakusho Kabushiki Kaisha), the removing liquid (removing liquid) was sprayed to the resist at a jetting pressure of 1.5 kg/cm 2 to thereby perform the removal of the resist. In this example, the above treatments were performed also for ten samples. As for each of the samples, the situation of the resist to have been removed was examined, and the totalized result was shown in Table 2, in which the removing period of time is the mean value among the ten samples. developing period of time swelling or/and dissolution of the non-exposed portion stain Example 1 45 seconds not observed not observed Example 2 40 seconds not observed not observed Comparative Example 1 1 mins. and 20 secs. much observed in the edge portion partly observed Comparative Example 2 1 mins. and 50 secs. not observed partly observed removing period of time stain Example 3 5 minutes not observed Example 4 5 minutes not observed Comparative Example 3 6 mins. and 50 secs. partly observed Comparative Example 4 7 mins. and 40 secs. entirely observed Application Example 1 Following the production procedures schematically shown in FIG. 4(A) through FIG. 4(F), the resist removing process of the present invention was performed to produce an ink jet recording head. Firstly, as shown in FIG. 4(A), there was provided a glass base member 40 having a electrothermal converting body formed thereon, which is capable of serving as the energy generating body 41 to generate energy to be utilized for discharging ink. Then, as shown in FIG. 4(B), on the glass base member 40 was laminated a 50 µm thick photosensitive resin layer 42 comprising a positive type photosensitive resin film (commercially available under the trademark of OZATEC R225, product by Hoechst Japan Kabushiki Kaisha) as the resist at 100 °C and at a pressure of 3 kg/cm 2 . A photomask (not shown in the figure) was superposed on the photosensitive resin layer 42, followed by irradiation of ultraviolet rays to other than the portions at which ink pathways are to be formed at 70 mJ/cm 2 , to thereby form a latent image 43a indicated by dotted line in FIG. 4(C) at the photosensitive resin layer 42. Then, the base member 40 was fixed to the fixing table 3 of the resist removing apparatus of FIG. 3 in a state that the discharging outlet side is positioned with the face upward while slanting a bit so that the gas-liquid mixture jetted from the jetting nozzle 4 is allowed to smoothly flow from the throughhole side to the discharging outlet side. A 1% NaOH aqueous solution was used as the removing liquid (developing solution), and the circulating flow rate by means of the pump 7 was made to be 2 ℓ/minute. As the gas, nitrogen gas was used. The inside of the removal vessel 1 was brought to a reduced pressure of 10 mmHg by means of the pump 13. Under this state, the removing liquid (developing solution) and the nitrogen gas were mixed at a volume ratio of 1 : 1, and the gas-liquid mixture was jetted to the photosensitive resin layer 42 at a jetting pressure of 1 kg/cm 2 to thereby perform development as shown in FIG. 4(D). Successively, the resultant was rinsed with pure water, followed by drying. Then, as shown in FIG. 4(E), ARALDITE CY230/HY956 (trademark name, product by Ciba Geigy Company) as the pathway wall-forming material 44 for forming an ink pathway wall was applied at a thickness of 100 µm by means of an applicator so as to cover the photosensitive resin layer 43 patterned through the development. After the resultant having been allowed to stand at 30 °C for 12 hours to make the pathway wall-forming material 44 cured, ultraviolet rays were irradiated from the opposite sides of the base member at 3000 mJ/cm 2 to solubilize the patterned photosensitive resin layer 43. Thereafter, the throughhole 45 was formed by means of a cutting technique, and the base member 40 was fixed to the fixing table 3 of the resist removing apparatus of FIG. 1 such that the discharging outlet side is positioned with the face upward while slanting a bit so that the gas-liquid mixture jetted from the jetting nozzle 4 is allowed to smoothly flow from the throughhole side to the discharging outlet side. A 5% NaOH aqueous solution was used as the removing liquid (removing liquid), and the circulating flow rate by means of the pump 7 was made to be 2 ℓ/minute. As the gas, nitrogen gas was used. The inside of the removal vessel 1 was brought to a reduced pressure of 10 mmHg. Under this state, the removing liquid (removing liquid) and the nitrogen gas were mixed at a volume ratio of 1 : 1, and the gas-liquid mixture was jetted to the patterned photosensitive resin layer 43 at a jetting pressure of 1.5 kg/cm 2 to thereby perform removal thereof. Successively, the resultant was rinsed with pure water, followed by drying. Thus, there was obtained an ink jet recording head schematically shown in FIG. 4(F). This ink jet recording head was found to have 128 discharging outlets 46a respectively of a rectangular shape of 50 µm x 60 µm, although only two discharging outlets being shown in the figure, ink pathways 46 in communication with the discharging outlets, and electrothermal converting bodies in the number corresponding thereto. This ink jet recording head was found not to have any residue of the photosensitive resin layer in the ink pathways, and it was found to excel in precision of the shape and that of the size of each ink pathway. The ink jet recording head thus obtained was set to the ink jet recording apparatus shown in FIG. 5 to discharge ink, and as a result, stable recording could be continuously performed over a long period of time, wherein excellent discharging characteristics as a whole were provided. Application Example 2 The procedures of Application Example 1 were repeated until the step of FIG. 4(C). Then, the base member 40 was fixed to the fixing table 3 of the resist removing apparatus of FIG. 3 in a state that the discharging outlet side is positioned with the face upward while slanting a bit so that the removing liquid and the gas jetted from the jetting nozzle 4 are allowed to smoothly flow from the throughhole side to the discharging outlet side. A 1% NaOH aqueous solution was used as the removing liquid (developing solution), and the circulating flow rate by means of the pump 7 was made to be 2 ℓ/minute. As the gas, nitrogen gas was used. The inside of the removal vessel 1 was brought to a reduced pressure of 10 mmHg by means of the pump 13. Under this state, the removing liquid (developing solution) and the nitrogen gas were alternately jetted to the photosensitive resin layer 42 at an interval of 1 second and at a jetting pressure of 1 kg/cm 2 to thereby perform development as shown in FIG. 4(D). Successively, the resultant was rinsed with pure water, followed by drying. Then, as shown in FIG. 4(E), ARALDITE CY230/HY956 (trademark name, product by Ciba Geigy Company) as the pathway wall-forming material 44 for forming an ink pathway wall was applied at a thickness of 100 µm by means of an applicator so as to cover the photosensitive resin layer 43 patterned through the development. After the resultant having been allowed to stand at 30 °C for 12 hours to make the pathway wall-forming material 44 cured, ultraviolet rays were irradiated from the opposite sides of the base member at 3000 mJ/cm 2 to solubilize the patterned photosensitive resin layer 43. Thereafter, the throughhole 45 was formed by means of a cutting technique, and the base member 40 was fixed to the fixing table 3 of the resist removing apparatus of FIG. 1 such that the discharging outlet side is positioned with the face upward while slanting a bit so that the removing liquid and the gas jetted from the jetting nozzle 4 are allowed to smoothly flow from the throughhole side to the discharging outlet side. A 5% NaOH aqueous solution was used as the removing liquid (removing liquid), and the circulating flow rate by means of the pump 7 was made to be 2 /minute. As the gas, nitrogen gas was used. The inside of the removal vessel 1 was brought to a reduced pressure of 10 mmHg by means of the pump 13. Under this state, the removing liquid (removing liquid) and the nitrogen gas were alternately jetted to the patterned photosensitive resin layer 43 at an interval of 1 second and at a jetting pressure of 1.5 kg/cm 2 to thereby perform removal thereof. Successively, the resultant was rinsed with pure water, followed by drying. Thus, there was obtained an ink jet recording head schematically shown in FIG. 4(F). This ink jet recording head was found to have 128 discharging outlets 46a respectively of a rectangular shape of 50 µm x 60 µm, although only two discharging outlets being shown in the figure, ink pathways 46 in communication with the discharging outlets, and electrothermal converting bodies in the number corresponding thereto. This ink jet recording head was found not to have any residue of the photosensitive resin layer in the ink pathways, and it was found to excel in precision of the shape and that of the size of each ink pathway. The ink jet recording head thus obtained was set to the ink jet recording apparatus shown in FIG. 5 to discharge ink, and as a result, stable recording could be continuously performed over a long period of time, wherein excellent discharging characteristics as a whole were provided. Application Example 3 The procedures of Application Example 1 were repeated, except for continuously changing the inner pressure of the removal vessel 1 in the developing step between 10 mmHg and 50 mmHg at a periodical cycle of one minute. The resultant ink jet recording head was found not to have any residue of the photosensitive resin layer in the ink pathways, and it was found to excel in precision of the shape and that of the size of each ink pathway. The resultant ink jet recording head was set to the ink jet recording apparatus shown in FIG. 5 to discharge ink, and as a result, stable recording could be continuously performed over a long period of time, wherein excellent discharging characteristics as a whole were provided. Application Example 4 The procedures of Application Example 2 were repeated, except for continuously changing the inner pressure of the removal vessel 1 in the removing step between 10 mmHg and 50 mmHg at a periodical cycle of one minute. The resultant ink jet recording head was found not to have any residue of the photosensitive resin layer in the ink pathways, and it was found to excel in precision of the shape and that of the size of each ink pathway. The resultant ink jet recording head was set to the ink jet recording apparatus shown in FIG. 5 to discharge ink, and as a result, stable recording could be continuously performed over a long period of time, wherein excellent discharging characteristics as a whole were provided.

Claims: A method of removing resist from a resist-coated base member including the steps of immersing the resist-coated base member in a resist-removing liquid, reducing the pressure above said resist-removing liquid to a pressure lower than atmospheric pressure,and jetting the said resist-removing liquid and a gas on to said resist-coated base member while it is so immersed, thereby removing said resist from said base member. A method according to claim 1 wherein said resist-removing liquid and said gas are mixed and jetted as a mixture in which the volume ratio of resist-removing liquid to gas lies in the range of 1:100 to 100:1. A method according to claim 1, in which the liquid and gas are jetted alternately. A method according to claim 3, in which the periodic cycle for the resist-removing liquid and gas to be alternately jetted is in the range 0.1 to 5.0 seconds. A method according to either preceding claim 3 or 4 in which the pressure of the jet of resist-removing liquid lies in the range of 0.001 to 10 Kg/cm 2 . A method according to any preceding claim carried out at a reduced pressure up to 5.33 x 10 4 Pa (400 mmHg). A method according to claim 3 or claim 4 in which the pressure is changed periodically during the resist-removal process. A method according to any preceding claim in which the gas is an inert gas. A method according to claim 8, in which the gas is one selected from He, Ne and Ar. A method according to any of claims 1 to 7, in which the gas is nitrogen. A method according to any preceding claim in which the resist to be removed is a positive-type photoresist. A method according to any preceding claim in which the base member from which the resist is to be removed is a portion corresponding to the ink pathway of an ink jet recording head. A method according to claim 12 in which a through hole is provided in the member and the direction of jetting is from the through hole to the discharging outlets of the recording head. A method of manufacturing an ink jet recording head comprising the steps of: removing resist from a resist-coated base member by the method of claim 13; and completing the manufacture of the base member to form the ink jet recording head. Apparatus adapted for carrying out a method according to any preceding claim, comprising an enclosed vessel for storing resist-removing liquid, a vacuum pump for reducing the pressure above the resist-removing liquid to a pressure below atmospheric pressure, a fixing table for supporting a base member within the liquid, means for circulating the liquid in the vessel so as to direct it as a jet on to the base member, and means for directing gas on to the base member.

Inventors: IMAMURA ISAO, IMAMURA, ISAO, IMAMURA, ISAO, CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1991
Main classification: G03F7
IPC codes: G03F7