Abstract:
The present invention is directed to apparatus and method for mixing at least two chemicals and supplying the mixture to a substrate treating apparatus for treating substrates using a mixture. The apparatus includes at least two chemical source sections; transfer lines connected to the chemical source sections respectively; a mina transfer line connected to the transfer lines and configured for mixing chemicals transferred from the transfer line and transferring the mixture to the treating apparatus; detectors for detecting flow rates of the chemicals transferred to the transfer lines respectively; and a control member for comparing flow rate data received from the detectors to control flow rates of chemicals.

Description:
PRIORITY STATEMENT  
       [0001]     This application claims priority of Korean Patent Application No. 2004-69931, filed on Sep. 2, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to apparatus and method for mixing at least two chemicals in determined mixing ratios and supplying the mixture in real time.  
         [0004]     2. Description of Related Art  
         [0005]     Generally, a mixture of a chemical and deionized water (DI water) or at least two chemicals is used in a wet etch for removing a wafer surface and a cleaning process.  
         [0006]     In a conventional chemical supply apparatus for mixing a chemical and DI water in a determined mixing ratio and supplying the mixture to a treating apparatus, chemicals are supplied to a mixing tank in determined their quantities, respectively. Supplying the chemicals is done by an integrating flowmeter installed at a transfer line, a control unit, and a shutoff valve opened/closed by the control unit. Namely, if a mixing ratio of A chemical to B chemical is 1:2 and a mixture of 300 liters is required, the chemical A and B are accumulated using an integrating flowmeter until their quantities reach 100 liters and 200 liters, respectively and the mixture of 300 liters is transferred to a buffer tank to be supplied to a treating apparatus.  
         [0007]     Generally, a conventional apparatuses does not support real-time mixture and supply of chemicals and has a complex configuration of two tanks and circulating lines connected with the tanks. Thus, lots of time and an extra install space are required and a chemical mixing and supply procedure becomes complex.  
       SUMMARY OF THE INVENTION  
       [0008]     Exemplary embodiments of the present invention provide apparatus and method for mixing at least two chemicals and supplying the mixture in real time. In an exemplary embodiment, the apparatus includes at least two chemical source sections; transfer lines connected to the chemical source sections respectively; a mina transfer line connected to the transfer lines and configured for mixing chemicals transferred from the transfer line and transferring the mixture to the treating apparatus; detectors for detecting flow rates of the chemicals transferred to the transfer lines respectively; and a control member for comparing flow rate data received from the detectors to control flow rates of chemicals.  
         [0009]     In some embodiments of the present invention, the control member includes flow rate control valves mounted on the transfer lines respectively and disposed in front of the detector; and a controller for receiving flow rate data from the detectors to, based on a flow rate of one of the chemicals, calculate a mixing ratio of the other chemicals and comparing the calculated mixing ratio with a preset mixing ratio to output a control signal for controlling open rates of the flow rate control valve.  
         [0010]     In some embodiments of the present invention, the apparatus further includes a drain line connected to the respective transfer lines for draining an initially flowing chemical of an irregular flow rate.  
         [0011]     In some embodiments of the present invention, the controller is a PID controller.  
         [0012]     In an exemplary embodiment, the method includes setting a mixing ratio of at least tow chemicals; transferring chemicals to a treating apparatus through transfer lines connected to chemical source sections respectively; detecting flow rates of the chemicals transferred to the transfer lines respectively; and comparing the detected flow rate data with a preset mixing ratio of chemicals to control flow rates of the chemicals.  
         [0013]     In some embodiments of the present invention, controlling the flow rates of the chemicals includes based on a flow rate of one of the chemicals, calculating a mixing ratio of the other chemicals; comparing the calculated mixing ratio with a preset mixing ratio; and controlling open rates of flow rate control valves mounted on the transfer lines respectively depending on the comparing result.  
         [0014]     In some embodiments of the present invention, controlling the flow rates of the chemicals includes based on a flow rate of one of the chemicals, calculating a mixing ratio of the other chemicals; comparing the calculated mixing ratio with a preset mixing ratio; and controlling open rates of flow rate control valves mounted on transfer lines corresponding to the other chemicals to control flow rates of the other chemicals depending on the comparing result.  
         [0015]     In some embodiments of the present invention, the method further includes draining initially transferred chemicals through the transfer line for a predetermined time.  
         [0016]     In some embodiments of the present invention, in the detection of the chemical flow rate, a chemical flow rate is detected since the chemical is transferred. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a configuration diagram of a chemical mixing and supply apparatus according to the present invention.  
         [0018]      FIG. 2  is a flowchart for explaining a chemical mixing and supply method according to the present invention.  
         [0019]      FIG. 3  is a configuration diagram of a buffer tank added to the chemical mixing and supply apparatus shown in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the height of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout.  
         [0021]     As illustrated in  FIG. 1 , a chemical mixing and supply apparatus  100  according to the present invention mixes a first chemical with a second chemical in a determined mixing ratio and supplying the mixture to a treating apparatus. The apparatus  100  includes first and second source sections  112  and  122 , first and second lines  114  and  124 , first and second flowmeters  116  and  126 , a control member  130 , and a main transfer line  140 .  
         [0022]     Shutoff valves M/V and A/V and a first flowmeter  116  are mounted on the first transfer line  114 . Shutoff valves M/V and A/V, a flow rate control valve, and a second flowmeter  126  are mounted on the second transfer line  124 . The first and second transfer lines  114  and  124  are connected to a main transfer line  140 . A drain line  150  is connected to the respective rear sides of the first and second transfer lines  114  and  124 .  
         [0023]     The first flowmeter  116  detects a flow rate of a first chemical flowing to the first transfer line  114 , and the second flowmeter  126  detects a flow rate of a second chemical flowing to the second transfer line  124 . Electric signals detected from flowmeters are transmitted to a controller  132  of the control member  130 . In some embodiments of the invention, a flowmeter may be any noncontact-type measurer.  
         [0024]     The control member  130  compares flow data provided from the first and second flowmeters  116  and  126  with a preset mixing ratio of chemicals to control flow rates of the chemicals. The control member  130  includes a flow rate control valve  134  and the controller  132 .  
         [0025]     The flow rate control valve  134  is mounted on the second transfer line  124  to be in front of the second flowmeter  126 . Also the flow rate control valve  134  may be mounted on a first transfer line. The controller  132  receives flow data detected from the first and second flowmeters and calculates a ratio of the second chemical based on the flow rate data of the first chemical. Further, the controller  132  compares the calculated ratio with a preset mixing ratio to output a control signal for controlling an open rate of the flow rate control valve  134  in real time. An air regulator  136  is controlled by the control signal output from the controller  132  and regulates the open rate of the flow rate control valve  134 .  
         [0026]     The controller  132  sounds an alarm and stops a chemical supply process or takes other actions. Preferably, the controller  132  feebacks a flow rate and adopts, for example, a proportional, proportional-integrate or proportional-integrate-derivative (PID) control scheme. The controller  132  may include a control computer of an apparatus configured for controlling an entire treating operation of a treating process. Additionally, the control computer may be a monitor allowing an operator to watch a flow rate control procedure.  
         [0027]     The above-described apparatus is configured for mixing chemicals in a preset mixing ratio and supplying the mixture in real time.  
         [0028]     A drain line  150  is connected to the respective first and second transfer lines  114  and  124 . Since an initially transferred chemical has a very irregular flow rate, it is drained through the drain line  150  for 3-5 seconds. Thereafter, a regular flow rate is maintained. That is, chemicals are drained in case of hunting in a flow rate. The drain line  150  may be connected to a chemical source section.  
         [0029]     The first and second chemicals having a flow rate controlled based on a preset mixing ratio by the control member  130  are supplied to the treating apparatus  10  through the main transfer line  140 . For example, a mixer  142  may be mounted on the main transfer line  140  for mixing the first and second chemicals more efficiently in real time.  
         [0030]     A buffer tank  160  may be installed between the first and second transfer lines  114  and  124  (see  FIG. 3 ) for preventing a chemical backflow resulting from a transfer pressure difference of chemicals transferred through the first and second transfer lines  114  and  124 .  
         [0031]     Although the apparatus as shown in  FIG. 1  mixes and supplies two kinds of chemicals, it may mix and supply at least two kinds of chemicals. Further, transferring chemicals is done by a conventional N 2  pressurizing manner or a conventional pumping manner.  
         [0032]     A chemical mixing and supply method will now be described with reference to a flowchart of  FIG. 2 . A mixing ratio (1:2) of a first chemical to a second chemical is set (S 12 ). Shutoff valves mounted on first and second transfer lines  114  and  124  are opened (S 14 ). Flow rates of the chemicals transferred to the first and second lines  114  and  124  are detected by flowmeters  116  and  126 , respectively (S 16 ). The chemicals are drained for a determined time and before their flow rates are controlled based on a preset mixing ratio (S 18 ). Stabilization of the chemical flow rate may be judged using flow rate data detected from first and second flowmeter.  
         [0033]     If the flow rates of the chemicals are stabilized, a controller  132  of a control member calculates flow rate data of the second chemical (e.g., 30 m 3 /s) based on flow rate data of the first chemical (e.g., 10 m 3 /s) (S 20 ). The controller  132  compares the calculated ratio (1:3) of the first chemical to the second chemical with a preset mixing ratio (1:2) (S 22 ) to output a signal for controlling an open rate of a flow rate control valve  134  mounted on the second transfer line  124  (S 24 ). The flow rate control valve  134  is controlled until a flow rate of the second chemical flowing to the second transfer line  124  reaches 20 m 3 /s.  
         [0034]     When the flow ratio of the first and second chemicals matches the preset mixing ratio, transferring the chemicals to a drain line  150  is stopped and transferring them to a main transfer line  140  starts (S 26 ).  
         [0035]     The first and second chemicals are mixed while being transferred to the main transfer line  140 , specifically, supplied to a treating apparatus after being mixed in a mixer  142  (S 28 ).  
         [0036]     According to the present invention, at least two chemicals are mixed and supplied in real time. Further, a configuration for supplying the determined quantity of chemicals as well as a chemical mixing and supply procedure is simple.  
         [0037]     Although the present invention has been described with reference to the preferred embodiments thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.