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  Processing method and processing apparatusUSPTO Application #: 20060088959Title: Processing method and processing apparatus Abstract: A processing method of subjecting at least two stacked films, which comprise a first film and a second film of a target object to be processed, to a removing process by wet etching comprises bringing a first process liquid into contact with the first film of the target object, thereby etching the first film, determining whether the first film has been removed or not, switching the first process liquid to a second process liquid differing in a condition from the first process liquid when it has been determined that the first film has been removed, and bringing the second process liquid into contact with the second film, thereby etching the second film. (end of abstract) Agent: Smith, Gambrell & Russell - Washington, DC, US Inventor: Glenn Gale USPTO Applicaton #: 20060088959 - Class: 438142000 (USPTO) Related Patent Categories: Semiconductor Device Manufacturing: Process, Making Field Effect Device Having Pair Of Active Regions Separated By Gate Structure By Formation Or Alteration Of Semiconductive Active Regions The Patent Description & Claims data below is from USPTO Patent Application 20060088959. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a processing method and a processing apparatus for removing by a wet etching a stacked films formed of at least two films which comprise a first film and a second film of a target object to be processed such as a semiconductor wafer, and a computer program, and a computer readable storage medium. [0003] 2. Description of the Related Art [0004] In recent years, the design rule of the semiconductor elements constituting an LSI is being made finer and finer in compliance with the demands for further improvements in the degree of integration and the operating speed of the LSI. In this connection, the gate insulating film is required to be made thinner in the MOS device. [0005] Conventionally, a silicon oxide film or a silicon oxynitride film has been used for forming the gate insulating film. In order to obtain a desired performance by using the gate insulating film formed of the material noted above, it is necessary to form the gate insulating film very thin. However, if the gate insulating film is made thinner, the gate leak current is increased, thereby increasing the operating power. [0006] Under the circumstances, a so-called "high-k material" such as HfO.sub.2, which has a relative dielectric constant higher than that of the conventional material, attracts attentions. Such being the situation, a gate insulating film of a two-layer structure prepared by forming a high-k material film on an interfacial oxide film consisting of a very thin SiO.sub.2 film has come to be used in place of the conventional gate insulating film formed of a silicon oxide film or a silicon oxynitride film. [0007] After formation of the gate insulating film of the two-layer structure, a polysilicon film or a metal film is formed on the gate insulating film, followed by removing the excess portion of the polysilicon film or the metal film by means of a RIE etching method, thereby forming a gate electrode. It should be noted in this connection, that, after formation of the gate electrode, it is necessary to remove selectively the remaining interfacial oxide film and the high-k material film in order to expose the source region and the drain region of the silicon substrate. [0008] In this case, it is necessary to remove selectively the interfacial oxide film (SiO.sub.2 film) and the high-k material film, for example, HfO.sub.2 film by means of the wet etching because a damage is done to the silicon substrate in the case of employing the RIE etching method. In the case of employing the wet etching method, however, serious problems are brought about as pointed out below. [0009] A dilute hydrofluoric acid is used in general for removing the SiO.sub.2 film by the wet etching method. However, the removing rate of the high-k material film such as a HfO.sub.2 film is very low under the conditions adapted for the removal of the SiO.sub.2 film to give rise to the difficulty that a long time is required for the removal of the high-k material film. In addition, SiO.sub.2 exhibits an etching rate higher than that exhibited by the high-k material to give rise to an inconvenience that SiO.sub.2 in the element separating region is also removed in the etching stage of the high-k material film. [0010] In order to overcome the inconvenience pointed out above, it is conceivable to use a chemical liquid exhibiting a reverse selectivity. If the two layers noted above are removed by the etching with such a chemical liquid, however, another inconvenience is generated such that an under-cut is generated in the high-k material film because the high-k material film exhibits a high etching rate. [0011] As pointed out above, where the two layers are removed by the wet etching, an inconvenience accompanying the etching selectivity is brought about. A technology adapted for overcoming the inconvenience pointed out above is disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 2004-179583. Specifically, it is disclosed in this patent document that a wet etching is performed by using a dilute hydrofluoric acid as the chemical liquid and by defining the hydrofluoric acid concentration of the dilute hydrofluoric acid such that the two layers are etched non-selectively. [0012] The technology disclosed in the patent document quoted above certainly permits overcoming the problems based on the etching selectivity. However, the etching conditions are not necessarily satisfactory to the two layers that are to be etched. In some cases, an inconvenience is generated such that the etching rate is rendered low. BRIEF SUMMARY OF THE INVENTION [0013] An object of the present invention is to provide a processing method and a processing apparatus, which do not bring about a problem in terms of the etching selectivity and which permit etching at least two stacked films of a target object to be processed at a sufficiently high etching rate in removing the two films noted above by the wet etching. [0014] Another object of the present invention is to provide a computer program for executing the processing described above and to provide a storage medium that can be read by a computer. [0015] According to a first aspect of the present invention, there is provided a processing method of subjecting at least two stacked films, which comprise a first film and a second film of a target object to be processed, to a removing process by wet etching, comprising bringing a first process liquid into contact with the first film of the target object, thereby etching the first film, determining whether the first film has been removed or not, switching the first process liquid to a second process liquid differing from the first process liquid in a condition when it is determined that the first film has been removed, and bringing the second process liquid into contact with the second film, thereby etching the second film. [0016] According to a second aspect of the present invention, there is provided a processing method of subjecting at least two stacked films, which comprise a first film and a second film of a target object, to a removing process by wet etching, the method comprising Bringing a first process liquid into contact with the first film of the target object, the first process liquid being capable of etching the first film with a high etching selectivity relative to the second film, determining whether the first film has been removed or not, switching the first process liquid to a second process liquid differing from the first process liquid in a condition and capable of etching the second film with a high selectivity relative to the first film when it has been determined that the first film has been removed, and bringing the second process liquid into contact with the second film, thereby etching the second film. [0017] According to a third aspect of the present invention, there is provided a processing apparatus for removing by a wet etching at least two stacked films, which comprise a first film and a second film of a target object to be processed, the apparatus comprising a housing section housing the target object, a first process liquid supply section for supplying the first process liquid onto the target object housed in the housing section, thereby bringing the first process liquid into contact with the first film for proceeding the etching of the first film, a second process liquid supply section for supplying the second process liquid differing in the condition from the first process liquid onto the target object housed in the housing section, thereby bringing the second process liquid into contact with the second film for proceeding the etching of the second film, a detecting section for detecting the removed state of the first film, a switching section for switching the process liquid that is brought into contact with the target object from the first process liquid to the second process liquid, and a control section for determining whether the first film has been removed on the basis of the detected value in the detecting section and, when it has been determined that the first film has been removed, for transmitting to the switching section an instruction to switch the process liquid that is brought into contact with the target object from the first process liquid to the second process liquid. [0018] According to a fourth aspect of the present invention, there is provided a computer program including a soft ware which, when executed, causes the computer to control a processing apparatus for removing by a wet etching at least two stacked films, which comprise a first film and a second film of a target object to be processed, wherein the soft ware causes the computer to execute the operations of bringing a first process liquid into contact with the first film of the target object, thereby etching the first film, determining whether the first film has been removed or not, switching the first process liquid to a second process liquid differing in a condition from the first process liquid when it has been determined that the first film has been removed, and bringing the second process liquid into contact with the second film, thereby etching the second film. [0019] Further, according to a fifth aspect of the present invention, there is provided a storage medium that can be read by a computer, the storage medium including a soft ware which, when executed, causes the computer to control a processing apparatus for removing by a wet etching at least two stacked films, which comprise a first film and a second film of a target object to be processed, wherein the soft ware causes the computer to execute the operations of bringing a first process liquid into contact with the first film of the target object, thereby etching the first film, determining whether the first film has been removed or not, switching the first process liquid to a second process liquid differing in a condition from the first process liquid when it has been determined that the first film has been removed, and bringing the second process liquid into contact with the second film, thereby etching the second film. [0020] According to the present invention, at least two stacked films, which comprise a first film and a second film of the target object is removed by a wet etching. The first film is etched first with the first process liquid and, then, when it has been determined that the first film has been removed, the first process liquid is switched to the second process liquid differing in the condition from the first process liquid, thereby etching the second film with the second process liquid. It follows that, if an etchant that permits etching the first film with a high selectivity is used as the first process liquid for etching the first film, and if another etchant that permits etching the second film with a high selectivity is used as the second process liquid for etching the second film, both the first and second films can be etched with a high etching rate without giving rise to a problem in terms of the etching selectivity. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING [0021] FIG. 1 is schematic diagram showing as an example the construction of a processing apparatus used for working the present invention; Continue reading... Full patent description for Processing method and processing apparatus Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Processing method and processing apparatus patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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