Abstract:
Disclosed is a system for cleaning a substrate such as a semiconductor wafer in wet type to thereby reduce airborne molecular contaminants (AMCs) in a wet station and a cleaning room by efficiently exhausting fumes generated during a wet cleaning process. The system for cleaning the substrate includes: a housing; a plurality of bathes placed inside of the housing; a transferring means placed on a top portion of the plurality of bathes for transferring a substrate; a first exhausting means connected to the plurality of bathes for exhausting fumes inside of the plurality of bathes; and a second exhausting means placed in a space inside of the housing and outside of the plurality of bathes for exhausting chemical fumes.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a system for cleaning a substrate such as a semiconductor wafer in wet type; and more particularly, to a system for reducing airborne molecular contaminants (AMCs) in a wet station and a cleaning room by efficiently exhausting fumes generated during a wet cleaning process.  
       DESCRIPTION OF RELATED ARTS  
       [0002]     As is known well, a substrate should be subjected to a wet cleaning process to continue a subsequent process after performing a series of steps such as depositing a thin layer, etching, polishing, and implanting ions. A wet station includes a plurality of bathes having different chemicals; and thus, the substrate is sequentially transferred to each bath closely placed with each other.  
         [0003]      FIG. 1  is a diagram conceptually illustrating a conventional chemical mechanical polishing (CMP) wet station.  
         [0004]     As shown, a plurality of bathes  102 A,  102 B,  102 C and  102 D are placed at a bottom portion of a housing  101 . As for a substrate transferring device, a plurality of robot arms  103 A,  103 B,  103 C,  103 D and  103 E are placed at a top portion inside of the housing  101  where is above the plurality of bathes  102 A to  102 D. Herein, the reference numerals from  102 A to  102 D express a first bath to a fourth bath, respectively. Also, the reference numerals from  103 A to  103 E express a first to a fifth robot arms, respectively. A substrate entrance enabled with opening and closing actions is formed on each of the first to the fourth bathes  102 A to  102 D. Thus, the first to the fifth robot arms  103 A to  103 E either put the substrate into the first to the fourth bathes  102 A to  102 D or take out the substrate from the first to the fourth bathes  102 A to  102 D through the substrate entrance.  
         [0005]     Each of the first to the fourth bathes  102 A to  102 D contains chemicals based on each cleaning step. For instance, a standard clean  1  (SC 1 ), i.e., a mixed solution of ammonium hydroxide (NH 4 OH), hydrogen peroxide (H 2 O 2 ) and deionized (DI) water, is contained in the first and the second bathes  102 A and  102 B. The third bath  102 C contains NH 4 OH, and the fourth bath  102 D contains hydrogen fluoride (HF).  
         [0006]     The first to the fifth robot arms  103 A to  103 E are controlled by a device controller. One selected robot arm  103 A,  103 B,  103 C,  103 D or  103 E, for instance, the first robot arm  103 A, is supposed to enter into the corresponding bath  102 A,  102 B,  102 C or  102 D, in this example, the first bath  102 A at a set time and lift a cleaned substrate from the selected bath  102 A. Then, the first robot arm  103 A moves next and puts the substrate into another bath, i.e., the second bath  102 B, next to the previous bath, i.e., the first bath  102 A. Afterwards, the first robot arm itself  103 A is taken out of the second bath  102 B. By repeating this step, a cleaning process is completed after applying this step to the last bath, in this example, the fourth bath  102 D.  
         [0007]     The substrate taken out of the last bath, i.e., the fourth bath  102 D, is transferred to a dry equipment  105  and becomes dry. It is general that the dry equipment  105  is placed beside the last bath in the housing of the wet cleaning device, thereby completing the cleaning process with the series of steps for cleaning in wet type and drying. A fan filter unit (FFU)  107  for blowing the air into the housing  101  is placed on an upper portion of the dry equipment  105 . The fan filter unit (FFU)  107  serves a role in preventing particles from adsorbing on the substrate.  
         [0008]     Meanwhile, an exhaust pipe  106  for draining the chemicals and exhausting the contaminants is interconnected to each of the first to the fourth bathes  102 A to  102 D. The conventional exhaust pipe  106  does not exist inside of the housing  101  for moving the first to the fifth robot arms but only being interconnected to each of the first to fourth bathes  102 A to  102 D.  
         [0009]     Accordingly, the conventional cleaning device contains a plenty of airborne molecular contaminants (AMCs) inside of the housing. These contaminants are mostly produced due to an evaporation of the chemicals contained in the bathes and stained on the robot arms and the lifted substrate from the bathes.  
         [0010]     Furthermore, the inside of the housing is not a closed space from the cleaning room, and thus, contamination of the cleaning room also becomes serious. Specifically, fumes are diffused into the cleaning room outside of the housing through a hole for putting the substrate into the housing and taking the substrate out of the housing and through a gap of the substrate entrance placed in the housing, and these diffused fumes induce a serious problem in cleanness of the cleaning room. Particularly, in case of containing the fan filter unit (FFU) inside of the cleaning device, it is very fast that the chemical components within the cleaning device leak to the cleaning room.  
       SUMMARY OF THE INVENTION  
       [0011]     It is, therefore, an object of the present invention to provide a method and system for cleaning a substrate capable of reducing airborne molecular contaminants (AMCs) in a wet station and a cleaning room by sufficiently exhausting fumes generated during a wet cleaning process.  
         [0012]     In accordance with one aspect of the present invention, there is provided a system for cleaning a substrate, including: a housing; a plurality of bathes placed inside of the housing; a transferring means placed on a top portion of the plurality of bathes for transferring a substrate; a first exhausting means connected to the plurality of bathes for exhausting fumes inside of the plurality of bathes; and a second exhausting means placed in a space inside of the housing and outside of the plurality of bathes for exhausting chemical fumes.  
         [0013]     In accordance with another aspect of the present invention, there is provided a system for cleaning a substrate installed inside of a cleaning room, including: a housing; a plurality of bathes placed inside of the housing; a transferring means placed on a top portion of the plurality of bathes for transferring a substrate; a first exhausting means connected to the plurality of bathes for exhausting fumes generated inside of the plurality of bathes out of the cleaning room; and a second exhausting means placed inside of the housing and outside of the plurality of bathes for exhausting chemical fumes out of the cleaning room. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The above and other objects and features of the present invention will become better understood with respect to the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:  
         [0015]      FIG. 1  is a configuration diagram conceptually illustrating a cleaning device after performing a conventional chemical mechanical polishing process;  
         [0016]      FIG. 2  is a configuration diagram briefly illustrating a cleaning device in accordance with a preferred embodiment of the present invention;  
         [0017]      FIG. 3A  is a perspective view illustrating a cleaning device shown in  FIG. 2 ;  
         [0018]      FIG. 3B  is a perspective view illustrating a cleaning device in accordance with another preferred embodiment of the present invention;  
         [0019]      FIG. 3C  is a top view illustrating a cleaning device shown  FIG. 3B ; and  
         [0020]      FIGS. 4A and 4B  are graphs illustrating measurement results of ammonia (NH 3 ) concentration inside of a cleaning room and a cleaning device measured through employing a method for measuring airborne molecular contaminants (AMCs). 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Hereinafter, detailed descriptions on a preferred embodiment of the present invention will be provided with reference to the accompanying drawings.  
         [0022]      FIGS. 2 and 3 A are a configuration diagram and a perspective view briefly illustrating a cleaning device in accordance with a preferred embodiment of the present invention, respectively.  
         [0023]     Referring to  FIGS. 2 and 3 A, the cleaning device in accordance with the present invention includes a plurality of bathes  202 A to  202 D placed on a bottom portion of a housing  201  and a plurality of robot arms  203 A to  203 E on a top portion of the housing  201 , where is above the plurality of bathes  202 A to  202 D. A substrate entrance enabled with opening and closing actions is formed on a top side of each of the bathes  202 A to  202 D. Thus, the plurality of robot arms  203 A to  203 E put the substrate into the corresponding bathes  202 A to  202 D and take the substrate out of the bathes  202 A to  202 D through the substrate entrance.  
         [0024]     Each of the plurality of bathes  202 A to  202 D contains chemicals based on each sequential cleaning step. For instance, a standard clean  1  (SCl), i.e., a mixed solution of ammonium hydroxide (NH 4 OH), hydrogen peroxide (H 2 O 2 ) and deionized (DI) water, is contained in the bathes  202 A and  202 B. Herein, the reference numerals from  202 A to  202 D will be referred to as a first to a fourth bathes, respectively. The third bath  202 C contains NH 4 OH, and the fourth bath  202 D contains hydrogen fluoride (HF).  
         [0025]     The robot arms  203 A to  203 E are controlled by a device controller  204 . Each of the robot arms  203 A to  203 E is supposed to enter into the corresponding first to fourth bathes  202 A to  202 D at a set time and lift a cleaned substrate from the selected bath  202 A,  202 B,  202 C or  202 D. Herein, it is assumed that the first robot arm  203 A puts the substrate into the first bath  202 A. Then, the first robot arm  203 A moves next and puts the substrate into another bath, i.e., the second bath  202 B, next to the previous bath, i.e., the first bath  202 A. Afterwards, the first robot arm itself  203 A is taken out of the second bath  202 B. By repeating this step, a cleaning process is completed after applying this step to the last bath, in this case, the fourth bath  202 D.  
         [0026]     Each of the first to the fourth bathes  202 A to  202 D is interconnected to a first exhaust member  206  for draining the chemicals and exhausting the contaminants, wherein the first exhaust member  206  is provided with a first exhaust pipe  206 A and a first exhaust outlet  206 B.  
         [0027]     The substrate taken out of the last bath is transferred to a dry equipment  205  and becomes dry. It is general that the dry equipment  205  is placed beside the last bath in the housing  201  of the wet cleaning device, thereby completing the cleaning process with the series of steps for cleaning in wet type and drying. A fan filter unit (FFU)  207  for blowing the air into the housing  201  is placed on an upper portion of the dry equipment  205 . The fan filter unit (FFU)  207  serves a role in preventing particles from adsorbing on the substrate.  
         [0028]     Most importantly, a second exhaust member  208  is formed for exhausting chemical fumes in an area inside of the housing  201  and outside of the first to the fourth  202 A to  202 D, wherein the second exhaust member  208  is provided with a second exhaust pipe  208 A and a second exhaust outlet  208 B. Typically, a process for fabricating a semiconductor device is performed in a cleaning room, and a cleaning device is also installed in the cleaning room. Thus, if the second exhaust pipe  208 A is interconnected with a main exhaust pipe of the cleaning room, it is possible to exhaust the chemical fumes out of the cleaning room. Accordingly, it is further possible to improve a problem of airborne molecular contaminants generated inside of the cleaning room and the housing  201 .  
         [0029]     A second exhaust outlet  208 B is made on one side of the housing  201  and then, the second exhaust pipe  208 A is interconnected to the second exhaust outlet  208 B. It is preferable that the second exhaust pipe  208 A can be separated from the second exhaust outlet  208 B of the housing  201  by considering maintenance of the equipment.  
         [0030]      FIGS. 3B and 3C  are a perspective view and a top view briefly illustrating a cleaning device in accordance with another preferred embodiment of the present invention, respectively. Herein, constitution elements of  FIGS. 3B and 3C  are denoted with the same numeral references as  FIGS. 2 and 3 A.  
         [0031]     By considering that the air sectionally flows into the housing  201  due to the fan filter unit (FFU)  207 , it is preferable to locate the second exhaust outlet  208 B with which the second exhaust pipe  208 A is interconnected in a place where the chemical fumes maintain a high concentration inside of the housing  201 . Since the FFU  207  is placed on a top portion of the dry equipment  205 , it is preferable to place the second exhaust outlet  208 B on a top portion of the first bath  202 A in opposition to the FFU  207 .  
         [0032]     Also, if necessary, it is possible to install a number of exhaust outlets and exhaust pipes in a number of places. Furthermore, it is possible to install at least one exhaust outlet and at least one exhaust pipe on a top side or/and a lateral side of the housing  201 . However, in accordance with the present invention, since the device controller  204  is placed on the top side of the housing  201 , the second exhaust outlet  208 B and the second exhaust pipe  208 A are installed on the lateral side of the housing  201  because the top side of the housing  201  does not have enough spaces. In case of changing a location and a size of the device controller  204 , it is more preferable to install the second exhaust outlet  208 B and the second exhaust pipe  208 A on the top side of the housing than to install the second exhaust outlet  208 B on the lateral side of the housing  201  in terms of efficiency on exhausting.  
         [0033]     In accordance with the present invention, a size of the exhaust outlet ranges from approximately 100 Φ to approximately 200 Φ and the second exhaust pipe  208  is formed by using a polyvinyl chloride (PVC)-based hose that can be bended.  
         [0034]     Furthermore, it is preferable to set an amount of the air exhausted through the second exhaust pipe  208  at a range from approximately 60% to approximately 70% of an amount of the air flowed into the housing  201 .  
         [0035]      FIGS. 4A and 4B  are graphs illustrating measurement results of ammonia (NH 3 ) concentration inside of a cleaning room and a cleaning device through employing a method for measuring airborne molecular contaminants (AMCs).  
         [0036]     The airborne molecular contaminants (AMCs) are gaseous molecular substances being generated during fabricating a semiconductor device and acting as a contaminant degrading yields of a product. The AMCs affect not only a product but also a human body. However, the AMCs typically show approximately 1,000 times more sensitive reaction to the product than the human body depending on components of the product.  
         [0037]     There are various methods for measuring the AMCs. However, among these various methods, it is widely used to sample contaminants with use of an impinger and then, analyze anions and cations first with use of an analysis apparatus, i.e., an ion chromatograph, and analyze boron, phosphorus and metallic components with use of an inductively coupled plasma-mass spectrometer (ICP-MS).  
         [0038]     Particularly, ammonia (NH 3 ) among the AMCs acts as a main source for generating a defect in a photolithography process. Accordingly, the inside of the cleaning room should be maintained at approximately 1 ppb, i.e., 0.001 ppm. Ammonia (NH 3 ) also has a bad effect on the human body.  
         [0039]      FIGS. 4A and 4B  illustrate a fixed quantity obtained by first pouring ultra pure water (UPW) of approximately 50 mL into the impinger of approximately 70 mL, collecting the air into the ultra pure water as sucking the air of approximately 1 liter/min for more than approximately 5 hours with use of a sucking pump and then, analyzing the collected air with use of the ion chromatograph.  
         [0040]      FIG. 4A  shows the result of a measured concentration of ammonia (NH 3 ) inside of the cleaning room in which the cleaning device is installed. In case of installing the second exhaust pipe for exhausting the fumes inside of the housing  201 , i.e., after an improvement, the concentration of ammonia (NH 3 ) is improved as much as approximately 92% compared with a state in which the first exhaust pipe directly interconnected to the first to the fourth bathes only exist, i.e., before the improvement. That is, the concentration of ammonia (NH 3 ) is approximately 1000 ng/L before the improvement; however, the concentration of ammonia (NH 3 ) is greatly decreased up to 80 ng/L after the improvement.  
         [0041]      FIG. 4B  shows the result of a measured concentration of ammonia (NH 3 ) dispersed inside of the housing of the cleaning device. As shown, compared with the concentration of ammonia (NH 3 ) before the improvement approximately 70% of ammonia (NH 3 ) concentration is obtained after the improvement.  
         [0042]     The present invention efficiently reduces the airborne molecular contaminants (AMCs) inside of the cleaning device and the cleaning room, thereby minimizing an effect on a human body and preventing degradation of reliability and yields of products usually caused by the contamination in the substrate.  
         [0043]     The present application contains subject matter related to the Korean patent application No. KR 2004-0034925, filed in the Korean Patent Office on May 17, 2004, the entire contents of which being incorporated herein by reference.  
         [0044]     While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.