Abstract:
A brush scrubbing apparatus is made up of a wafer holder which retains a wafer, a brush which removes a particle on the wafer, a driver which rotates at least one of the wafer holder and the wafer, an alignment mechanism which defines a relative position between the brush and the wafer holder, and controller which controls the alignment mechanism responding to a driving power supply voltage in the driver. The brush scrubbing apparatus can precisely get the reference position for deciding the pushing distance without using the eye measurement.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the invention  
           [0002]    The present invention generally relates to a brush scrubbing apparatus, and more particularly, the present invention relates to the brush scrubbing apparatus for a semiconductor wafer.  
           [0003]    This application is a counterpart of Japanese application Serial Number 57166/1998, filed Mar. 9, 1998, the subject matter of which is incorporated herein by reference.  
           [0004]    2. Description of the Related Art  
           [0005]    In general, a conventional brush scrubbing apparatus has been used for scrubbing a semiconductor wafer. The conventional brush scrubbing apparatus has been disclosed in “SILICON WAFER HYOMEN NO KURINKA-GIJYUTU, KENJI SUGIMOTO et al, REALIZE INC, pp. 293-294”, and Japanese Patent Laid Open No. 8-206617.  
           [0006]    In the conventional brush scrubbing apparatus, a rotating brush pushes to the surface of the semiconductor wafer and moves along it while a cleaning solution such as deionized water is supplied to the rotating brush. As a result, the conventional brush scrubbing apparatus removes particles hydrodynamically while the rotating brush rubs the surface of the semiconductor wafer.  
           [0007]    More particularly, the conventional brush scrubbing apparatus retains the semiconductor wafer on a rotating turntable, the semiconductor wafer turns on a vertical axis while the deionized water is supplied to the surface of the semiconductor wafer. In this circumstances, a rotating brush mounted on a bottom portion of an arm, which moves above the semiconductor wafer, then contact to the surface of the semiconductor wafer via the dieionized water, and then thrusts the surface of the semiconductor wafer. And then the rotating brush moves along the surface of the semiconductor wafer. As a result, the conventional brush scrubbing apparatus removes particles.  
           [0008]    In the conventional brush scrubbing apparatus, a predetermined distance to be thrust downward from a reference position of brush, which influences a cleaning effect and a damage to the semiconductor wafer. The reference position is a position that the rotating brush contacts to the surface of the semiconductor wafer. The set of the reference position decides with an eye measurement. When adjusting the predetermined distance, it is precisely important to set the reference position.  
           [0009]    In the conventional brush scrubbing apparatus, it is desirable to precisely get the reference position for deciding the predetermined distance without using the eye measurement.  
         SUMMARY OF THE INVENTION  
         [0010]    An object of the present invention is to provide a brush scrubbing apparatus that can precisely get a position as the reference position that the brush contact to the surface of the semiconductor wafer without using an eye measurement.  
           [0011]    According to one aspect of the present invention, for achieving the above object, there is provided a brush scrubbing apparatus comprising: a rotating turntable which retains a wafer; a brush which removes a particle on the wafer; and a controller which detects a reference position responding to a change of a driving current value for driving the brush, and which stores a predetermined distance to thrust downward from the reference position; wherein the reference position is a position which the brush contacts to the wafer.  
           [0012]    According to another aspect of the present invention, for achieving the above object, there is provided a brush scrubbing apparatus comprising: a rotating turntable which retains a wafer; a brush which removes a particle on the wafer; and a controller which detects a reference position responding to a change of a first current value for driving the brush, which stores a predetermined distance to thrust downward from the reference position, and, and which stores a second current value for driving the brush when making go down the brush until the predetermined distance to thrust downward from the reference position, and which finds a differential value between the first and second current values and compares between the differential value and a predetermined threshold value; wherein the reference position is a position which the brush contacts to the wafer.  
           [0013]    According to another aspect of the present invention, for achieving the above object, there is provided a brush scrubbing apparatus comprising: a rotating turntable which retains a wafer; a brush which removes a particle on the wafer; a controller which detects a reference position responding to a change of a driving current value for driving the wafer, and which stores a predetermined distance to thrust downward from the reference position; wherein the reference position is a position which the brush contacts to the wafer.  
           [0014]    According to another aspect of the present invention, for achieving the above object, there is provided a brush scrubbing apparatus comprising: a brush holder; a brush; and a controller which detects a reference position responding to a change of a driving current value for driving the brush; wherein the reference position is a position which the brush contacts to the brush holder.  
           [0015]    According to another aspect of the present invention, for achieving the above object, there is provided a brush scrubbing apparatus comprising: a rotation holder; a brush; a tachometer which detects a rotation speed of the brush via the rotation holder; and a controller which detects a reference position responding to a signal when the brush contacts to the rotation holder.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    While the specification concludes claims particularly pointing out and distinctly claiming the subject matter that is regarded as the invention, the invention, along with the objects, features, and advantages thereof, will be better understood from the following description taken in connection with the accompanying drawings, in which:  
         [0017]    [0017]FIG. 1 is a diagram showing a brush scrubbing apparatus according to a first preferred embodiment of a present invention.  
         [0018]    [0018]FIG. 2 is a flow chart showing an operation of a brush scrubbing apparatus according to a first preferred embodiment of a present invention.  
         [0019]    [0019]FIG. 3 is a flow chart showing an operation of a brush scrubbing apparatus according to a second preferred embodiment of a present invention.  
         [0020]    [0020]FIG. 4 is a diagram showing a brush scrubbing apparatus according to a third preferred embodiment of a present invention.  
         [0021]    [0021]FIG. 5 is a diagram showing a brush scrubbing apparatus according to a fourth preferred embodiment of a present invention.  
         [0022]    [0022]FIG. 6 is a diagram showing a brush scrubbing apparatus according to a fifth preferred embodiment of a present invention.  
         [0023]    [0023]FIG. 7 is a flow chart showing an operation of a brush scrubbing apparatus according to a fifth preferred embodiment of a present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    A brush scrubbing apparatus according to a first preferred embodiment of a present invention will hereinafter be described in detail with reference to FIG. 1.  
         [0025]    [0025]FIG. 1 is a diagram showing a brush scrubbing apparatus according to a first preferred embodiment of a present invention.  
         [0026]    As shown in FIG. 1, a brush scrubbing apparatus is preferably made up of a wafer rotating apparatus  8 , a first voltage supply circuit  6 , a nozzle  3 , a brush  17 , a brush spin mechanism  25 , an arm mechanism  14 , an arm sing mechanism  15 , an arm up and down mechanism  16 , a second voltage supply circuit  31 , and a controller  53 . The wafer rotating apparatus  8  is preferably made up of a rotating turntable  1  which horizontally retain a semiconductor wafer  2  and which turns on a vertical axis, and a wafer spin motor  5 . The first voltage supply circuit  6  supplies a power to the wafer spin motor  5 . The nozzle  3  supplies a cleaning solution to a surface of the semiconductor wafer  2 . The brush  17  removes particles by contacting to the surface of the semiconductor wafer  2  while rotating. The brush spin mechanism  25  rotates the brush  17 , which is preferably made up of a brush spin motor  18 , a driving shaft  19  as a driving axis of the brush spin motor  18 , a driving gear  20  which mounted to the driving shaft  19 , a shaft  23  to be operated the brush  17 , a gear  22  to be operated the shaft  23 , and a transmission belt  21  which connect between the driving gear  20  and the gear  20 . The arm mechanism  14  retains the brush  17 . The arm sing mechanism  15  and the arm up and down mechanism  16  swing an arm (not shown) and go up and down the arm. The second voltage supply circuit  31  supplies a power with a power supply voltage line  30  to the brush spin mechanism  25 .  
         [0027]    Further, the brush scrubbing apparatus preferably includes a current detector  51  which detects a driving current value of the brush spin motor  18  between the brush spin motor  18  and the second voltage supply circuit  31 , the controller  53  which controls, responding to a signal from the current detector  51 , the arm sing mechanism  15 , an arm up and down mechanism  16 , the first voltage supply circuit  6 , and the second voltage supply circuit  31 , and a keyboard  55  for inputting a data to the controller  53 . In this apparatus, the controller  53  is preferably a microprocessor which comprises CPU, ROM, and RAM, for example.  
         [0028]    [0028]FIG. 2 is a flow chart showing an operation of a brush scrubbing apparatus according to a first preferred embodiment of a present invention.  
         [0029]    As shown in FIG. 2, the controller  53  inputs, in advance, a predetermined distance to thrust downward from a reference position that the brush contacts to the semiconductor wafer and a cleaning time, inputted by an operator via the keyboard (see S 1 ). Here, the reference position is a position that the rotating brush  17  contacts to the semiconductor wafer  17  surface.  
         [0030]    Next, the rotating turntable  1  horizontally retains the semiconductor wafer  2  thereon. The semiconductor wafer  2  turns on a vertical axis at a predetermined rotation speed. While supplying a deionized water to the semiconductor wafer  2  surface from the nozzle  3 , the brush  17  moves above the semiconductor wafer  2  edge using the arm sing mechanism  15 . At the same time, the controller  53  is applied a power from the second voltage supply circuit  31  to the brush spin motor  18 . As a result, the controller  53  rotates the brush  17  at a predetermined rotation speed (see S 2 ).  
         [0031]    Next, the brush  17  slowly goes down to the semiconductor wafer  2  surface by operating the arm up and down mechanism  16  (see S 3 ) . After operated above, the current detector  51  detects a driving current value of the brush spin motor  18  and outputs the driving current value to the controller  53 . The brush  17  tip contacts to the semiconductor wafer  2  surface, as a result the driving current value of the brush spin motor  18  changes. The controller  53  detects the reference position that the semiconductor wafer  2  surface contacts to the brush  17  tip responding to the change of the driving current value (see S 4 ) and stops going down to the semiconductor wafer  2  (see S 5 ). The reference position stores in the controller  53  (see  86 )  
         [0032]    Next, the controller  53  goes down the brush  17  until a predetermined distance to thrust downward from the reference point using the arm up and down mechanism  16 , and then the brush  17  is fixed (see  87 ).  
         [0033]    Next, a scrubbing treatment carries out by swinging an arm body  14  using the arm swing mechanism  15  (see  88 ).  
         [0034]    When the controller  53  detects a progress of the predetermined cleaning time (see S 9 ), the swing operation stops and then the arm body  14  goes up (see S 10 ).  
         [0035]    Finally, the semiconductor wafer  2  is dried.  
         [0036]    As mentioned above, the brush scrubbing apparatus according to the first preferred embodiment of the invention electrically detects the reference position that the brush contact to the semiconductor wafer  2  surface. Accordingly, it can precisely get the reference position without using an eye measurement.  
         [0037]    In the first preferred embodiment of the invention, the brush  17  goes up and down, but the semiconductor wafer  2  may be went up and down. The scrubbing step is carried out while rotating the semiconductor wafer  2 , but it may be carried out without rotating.  
         [0038]    A brush scrubbing apparatus according to a second preferred embodiment of a present invention will hereinafter be described in detail with reference to FIGS. 1 and 3.  
         [0039]    [0039]FIG. 3 is a flow chart showing an operation of a brush scrubbing apparatus according to a second preferred embodiment of a present invention.  
         [0040]    As shown in FIG. 3, the controller  53  inputs, in advance, a predetermined distance to thrust downward from a reference position that the brush contacts to the semiconductor wafer and a cleaning time, inputted by an operator via the keyboard (see S 21 ). Here, the reference position is a position that the rotating brush  17  contacts to the semiconductor wafer  17  surface.  
         [0041]    Next, the rotating turntable  1  horizontally retains the semiconductor wafer  2  thereon. The semiconductor wafer  2  turns on a vertical axis at a predetermined rotation speed. While supplying a deionized water to the semiconductor wafer  2  surface from the nozzle  3 , the brush  17  moves above the semiconductor wafer  2  edge using the arm sing mechanism  15 . At the same time, the controller  53  is applied a power from the second voltage supply circuit  31  to the brush spin motor  18 . As a result, the controller  53  rotates the brush  17  at a predetermined rotation speed (see S 22 ).  
         [0042]    Next, the brush  17  slowly goes down to the semiconductor wafer  2  surface by operating the arm up and down mechanism  16  (see S 23 )  
         [0043]    After that, the current detector  51  detects a driving current value of the brush spin motor  18  and outputs the driving current value to the controller  53 . The brush  17  tip contacts to the semiconductor wafer  2  surface, as a result the driving current value of the brush spin motor  18  changes. The controller  53  detects the reference position that the semiconductor wafer  2  surface contacts to the brush  17  tip responding to the change of the driving current value (see S 24 ) and stops going down to the semiconductor wafer (see S 25 ).  
         [0044]    The reference position stores in the controller  53  (see S 26 )  
         [0045]    Next, the controller  53  goes down the brush  17  until a predetermined distance to thrust downward from the reference point using the arm up and down mechanism  16 , and then the brush  17  is fixed (see S 27 ).  
         [0046]    Further, in this time, the controller  53  stores a current value as a reference current value I ref  of a brush spin motor  18 (see S 28 ) . The reference current value I ref  is used to constantly control the reference position responding to patterns formed on the semiconductor wafer surface.  
         [0047]    Next, a scrubbing treatment carries out by swinging an arm body  14  using the arm swing mechanism  15  (see S 29 ).  
         [0048]    In this time, the controller  53  stores a current value of a brush spin motor  18 . Then, it compares between the current value and the reference current I ref . As a result, it finds a differential value D(=I-I ref ) between a driving current value (I) and the reference current I ref  (see S 30 ).  
         [0049]    The controller  53  compares between the differential value D and a predetermined threshold value ε. The predetermined threshold value ε is a permissible rage for a change from the reference current I ref  (see S 31 ).  
         [0050]    When the differential value D is more than the threshold value ε, the arm mechanism  16  controls responding to the differential value D so that the driving current value during the scrubbing step makes equal the reference current I ref  (see S 32 ).  
         [0051]    The S 30 -S 32  steps during a scrubbing step is continuously carried out.  
         [0052]    When the controller  53  detects to terminate the predetermined cleaning time (see S 33 ), the swing operation stops and then the arm body  14  goes up (see S 34 ).  
         [0053]    Finally, the semiconductor wafer  2  is dried.  
         [0054]    As mentioned above, the second preferred embodiment of a present invention controls the reference position responding to the patterns formed on the semiconductor wafer, at real-time processing. Accordingly, the second preferred embodiment of a present invention can constantly maintain the reference position corresponding to the patterns formed on the semiconductor wafer  2  surface during scrubbing.  
         [0055]    A brush scrubbing apparatus according to a third preferred embodiment of a present invention will hereinafter be described in detail with reference to FIG. 4.  
         [0056]    [0056]FIG. 4 is a diagram showing a brush scrubbing apparatus according to a third preferred embodiment of a present invention.  
         [0057]    The third preferred embodiment of a present invention finds a reference position using a driving current value of the wafer spin motor  5  when a brush  17  tip contacts to a semiconductor wafer  2  surface. Accordingly, the third preferred embodiment can adopt the brush scrubbing apparatus having a structure so that a brush  17  does not have a rotating function, or the brush  17  fixes to an arm body  14 . The third preferred embodiment includes a current detector  51  to detect a driving current value of the wafer spin motor  5 , which forms between the wafer spin motor  5  and a voltage supply circuit  6 . A controller  53  receives a signal from the current detector  51 . As a result, it controls an arm sing mechanism  15 , and the arm up and down mechanism  16 . The third preferred embodiment can control in a similar manner as the first and second preferred embodiments using the driving current value of the wafer spin motor  5  instead of the driving current value of the brush spin motor  18  in accordance with the flow charts showing the operation of the brush scrubbing apparatus according to the first and second preferred embodiments.  
         [0058]    As mentioned above, the third preferred embodiment of the present invention can adopt the brush scrubbing apparatus having a structure so that a brush does not have the rotating function, or the brush  17  fixes to an arm body. Accordingly, the third preferred embodiment can decrease a size of the brush scrubbing apparatus.  
         [0059]    A brush scrubbing apparatus according to a fourth preferred embodiment of a present invention will hereinafter be described in detail with reference to FIG. 4.  
         [0060]    [0060]FIG. 5 is a diagram showing a brush scrubbing apparatus according to a fourth preferred embodiment of a present invention.  
         [0061]    The fourth preferred embodiment of a present invention can electrically detect an abrasion and a fatigue of the brush. The fourth preferred embodiment of a present invention adds a brush holder  61  to the first preferred embodiment. The brush holder  61  forms so as to make possible to revolve near the wafer rotating apparatus  8 .  
         [0062]    The brush  17  is moved above the brush holder  61  surface using the arm swing mechanism  15 . Next, the brush  17  slowly goes down to the brush holder  61  by the arm up and down mechanism  16  while rotating the brush  17  at a predetermined spin speed. Then, the brush  17  tip contacts to the brush holder  61  and then if a driving current value oh the brush spin motor  18  changes, the controller  53  detects a position that the brush  17  tip contacts to the brush holder  61  responding to the change of the driving current value, the arm stops going down, and the position is stored. After that, the arm goes up. The arm is returned to the beginning stage.  
         [0063]    The steps as mentioned above is carried out at a predetermined frequency. As a result, the fourth preferred embodiment of a present invention can appropriately adjust a distance to thrust downward from a reference position that the brush contacts to the semiconductor wafer on the basis of a degree of the abrasion and the fatigue of the brush.  
         [0064]    A brush scrubbing apparatus according to a fifth preferred embodiment of a present invention will hereinafter be described in detail with reference to FIG. 6 and FIG. 7.  
         [0065]    [0065]FIG. 6 is a diagram showing a brush scrubbing apparatus according to a fifth preferred embodiment of a present invention. FIG. 7 is a flow chart showing an operation of a brush scrubbing apparatus according to a fifth preferred embodiment of a present invention.  
         [0066]    The fifth preferred embodiment of a present invention is characterized to have a tachometer  65  for detecting a rotation speed of the brush.  
         [0067]    The brush  17  is moved above the rotation holder  67  of the tachometer  65  using the arm swing mechanism  15  (see S 31 ). Next, while rotating the brush  17  at a predetermined spin speed (see S 32 ), the brush  17  slowly goes down to the rotation holder  67  using the arm up and down mechanism  16  (see S 33 ). Then, the brush  17  tip contacts to the rotation holder  67 . As a result, the rotation holder  67  starts to rotate. The controller  53  finds a first position that the brush  17  contacts to the semiconductor wafer  2  by receiving a signal of the tachometer  65  for detecting a rotation (see S 34 ). The arm stops going down (see S 35 ), and the first position is stored (see S 36 ).  
         [0068]    The controller  53  finds, in advance, a second position that the brush  17  contacts to the semiconductor wafer  2 , in a beginning stage for brush scrubbing steps. The controller  53  compares between the first and second positions. As a result, it can find the abrasion volume from a difference between the first and second positions. A predetermined reference abrasion volume compares with the found abrasion volume (see S 37 ). After that, the arm goes up. The arm is returned to the beginning stage.  
         [0069]    The fifth preferred embodiment of a present invention carries out the steps as mentioned above at a predetermined frequency. As a result, it can precisely find the abrasion volume of the brush  17 .  
         [0070]    While the present invention has been described with reference to the illustrative embodiments, this description is not intended to be construed in a limiting sense various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to those skilled in the art on reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.