Patent Publication Number: US-2010108106-A1

Title: Substrate cleaning apparatus

Description:
TECHNICAL FIELD 
     This invention relates to a substrate cleaning apparatus for cleaning substrates such as semiconductor wafers and glass substrates for liquid crystal displays (hereinafter called simply “substrates”) with a treating liquid. 
     BACKGROUND ART 
     The apparatus of this type conventionally includes a treating unit for storing a treating liquid, a supply pipe for supplying deionized water to the treating unit, a mixing valve for mixing a chemical solution to the deionized water flowing through the supply pipe, a branch pipe for supplying the chemical solution to the mixing valve, and a chemical tank connected in communication with the branch pipe. See, for example, Patent Document 1. In the substrate cleaning apparatus with such a configuration, the chemical solution (for example, hydrofluoric acid) stored in the chemical tank is mixed into the deionized water from the mixing valve to perform a cleaning treatment to the substrates accommodated in the treating unit. 
     Patent Document 1: Japanese Unexamined Patent Publication H11-67707A. 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention  
     The conventional apparatus having such a configuration, however, have the following drawback. That is, deionized water has extremely high cleanliness in ppt-level, and substrates are rarely contaminated due to the deionized water. On the other hand, a chemical solution has lower cleanliness than deionized water, and thus substrates may be contaminated due to the chemical solution. Specifically, in supplementing the chemical solution to the chemical tank through the chemical supply line, particles may be mixed through the supplementing line, or a metal ion may be eluted and mixed into the chemical solution, thereby reducing cleanliness of the chemical solution. As a result, the substrates can never be cleaned at a high clean level even using the deionized water with high cleanliness for cleaning. 
     This invention has been made in view of the state of the art noted above, and its object is to provide a substrate cleaning apparatus capable of cleaning substrates at a high clean level by improving cleanliness of a chemical solution. 
     Means for Solving the Problem  
     This invention has a following configuration in order to achieve the above object. The apparatus of this invention is an apparatus for cleaning substrates with a treating liquid containing a chemical solution, including: 
     a treating unit for treating the substrates with the treating liquid; 
     a supply pipe for supplying deionized water to the treating unit; 
     a chemical supply unit for supplying the chemical solution to the supply pipe; and 
     a chemical cartridge for storing the chemical solution and removable from the chemical supply unit. 
     According to this invention, a chemical solution is mixed with deionized water from the chemical cartridge via the chemical supply unit to produce a treating liquid. Then, the treating liquid is supplied to the treating unit via the supply pipe. The chemical cartridge is not supplemented with the chemical solution through the supplementing line etc., and the chemical solution is not contaminated. As a result, cleanliness of the chemical solution can be kept high, and the substrates can be cleaned at a high clean level. 
     Moreover, the chemical cartridge in this invention preferably includes a controller for controlling a supply flow rate of the chemical solution. Furthermore, the chemical supply unit preferably includes an attachment portion to which the chemical cartridge can be attached. 
     According to this invention, the chemical cartridge can be directly attached to the supply pipe by attaching the chemical cartridge capable of controlling a flow rate of the chemical solution with the controller to the attachment portion, which can simplify the construction and can reduce apparatus cost. 
     Furthermore, the chemical supply unit in this invention preferably includes a mixing valve for mixing the chemical solution. The mixing valve preferably has a branch pipe through which the chemical solution is supplied. The branch pipe preferably has an attachment portion to which the chemical cartridge can be attached. 
     According to this invention, the chemical cartridge is attached to the attachment portion and the chemical solution is supplied to the mixing valve through the branch pipe. Thus, the mixing valve can supply a desired flow rate of the chemical solution to the deionized water. In addition, it only needs to provide the attachment portion on the branch pipe of the mixing valve included in the conventional apparatus. Consequently, a chemical cartridge system is easily applicable to the conventional apparatus. 
     Furthermore, the chemical cartridge in this invention preferably includes a residual quantity detecting sensor for detecting a quantity of the chemical solution currently stored inside. 
     According to this invention, replacement timing of the chemical cartridge can be easily recognized. 
     Furthermore, the chemical cartridge in this invention is preferably filled in advance with a hydrochloric acid solution produced by dissolving a hydrogen chloride gas in deionized water. 
     According to this invention, the hydrogen chloride gas is dissolved in the deionized water, thereby producing the hydrochloric acid solution with high cleanliness. Thus, there can be prevented reduction in cleanliness of the chemical solution during use. 
     Furthermore, the chemical cartridge in this invention is preferably filled in advance with an ammonia solution produced by dissolving an ammonia gas in deionized water. 
     According to this invention, the ammonia gas is dissolved in the deionized water, thereby producing the ammonia solution with high cleanliness. Thus, there can be prevented reduction in cleanliness of the chemical solution during use. 
     Furthermore, the chemical cartridge in this invention is preferably filled in advance with a hydrofluoric acid solution produced by dissolving a hydrogen fluoride gas in deionized water. 
     According to this invention, the hydrogen fluoride gas is dissolved in the deionized water, thereby producing the hydrofluoric acid solution with high cleanliness. Thus, there can be prevented reduction in cleanliness of the chemical solution during use. 
     EFFECT OF THE INVENTION 
     With the substrate cleaning apparatus according to this invention, the chemical solution is mixed with deionized water from the chemical cartridge via the chemical supply unit to produce the treating liquid. Then, the treating liquid is supplied to the treating unit via the supply pipe. The chemical cartridge is not supplemented with the chemical solution through the supplementing line etc., and the chemical solution is not contaminated. As a result, cleanliness of the chemical solution can be kept high, and the substrates can be cleaned at a high clean level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purpose of illustrating the invention, there are shown in the drawings several forms presently preferred, it being understood, however, that the invention is not limited to the precise arrangement and instrumentalities shown. 
         FIG. 1  is a schematic view of a substrate cleaning apparatus according to Embodiment 1; 
         FIG. 2  is a longitudinal sectional schematic view of a chemical cartridge; and 
         FIG. 3  is a schematic view of a substrate cleaning apparatus according to Embodiment 2. 
     
    
    
     DESCRIPTION OF REFERENCES 
     W substrate 
       1  treating tank 
       7  inner tank 
       9  outer tank 
       11  filling pipe 
       17  supply pipe 
       19  deionized water source 
       21  ozone water source 
       27  chemical source 
       29  chemical cartridge 
       37  cartridge body 
       39  residual quantity display portion 
       41  outer container 
       43  inner container 
       45  insert portion 
       47  nozzle portion 
       53  attachment portion 
       57  inlet 
     EMBODIMENT 1 
     Embodiment 1 of this invention will be described in detail hereinafter with reference to the drawings.  FIG. 1  is a schematic view of a substrate cleaning apparatus according to Embodiment 1. 
     The substrate cleaning apparatus of this embodiment is for instant an apparatus for performing a cleaning treatment to substrates W, and includes a treating tank  1  corresponding to the treating unit of this invention. The treating tank  1  has an inner tank  7  that stores a treating liquid while accommodating the substrates W, and an outer tank  9 . The inner tank  7  has one pair of filling pipes  11  on both sides of its bottom for supplying the treating liquid. The outer tank  9  encloses the lateral sides of an upper opening of the inner tank  7 , and collects and discharges the treating liquid overflowing the inner tank  7 . 
     One end of a supply pipe  17  is connected in communication with the filling pipes  11  of the treating tank  1 . The other end of the supply pipe  17  is connected in communication with a deionized water source  19  and an ozone water source  21  via a three-way valve  23 . The supply pipe  17  between the filling pipes  11  and the three-way valve  23  has a control valve  25  and a chemical supply unit  27  attached thereto. The chemical supply unit  27  has two or more types of removable chemical cartridges  29 , and supplies a proper chemical solution into the supply pipe  17  depending on treatments. 
     A substrate holding mechanism  31  includes a back plate  33  and a substrate holding guide  35 . The back plate  33  with a plate-like member is attached to a transport mechanism, not shown, in a suspended attitude. The back plate  33  can move vertically along the inner wall surface of the inner tank  7 . The substrate holding guide  35  for holding two or more substrates W in an erect attitude is attached on the front lower end of the back plate  33  with the longitudinal direction of the substrate holding guide  35  being horizontal. The substrate holding mechanism  31  is vertically movable between a treating position inside the inner tank  7  and a standby position above the inner tank  7  by a lifting mechanism not shown. 
     Reference is now made to  FIG. 2 .  FIG. 2  is a longitudinal sectional schematic view of the chemical cartridge. 
     The chemical cartridge  29  includes a cartridge body  37  and a residual quantity display portion  39 . The cartridge body  37  has an outer container  41 , an inner container  43 , an insert portion  45 , and a nozzle portion  47 . 
     The outer container  41  has a bottom  49  so as to form downward inclines toward the nozzle portion  47 , whereby the chemical solution hardly remains in the chemical cartridge. The inner container  43  is made from a material resistant to the chemical solution to be stored. The material is, for example, fluororesin, polypropylene, polyethylene, vinylidene chloride, etc. 
     The nozzle portion  47  corresponding to the controller of this invention has two or more outlets. Properly opening and closing of these outlets can control a supply rate of the chemical solution. The control unit not shown performs the above control. 
     A liquid level sensor  51  is embedded adjacent to the bottom  49  of the outer container  41 . The liquid level sensor  51  detects a level of the liquid in the inner container  43 , and outputs the resultant signal to the residual quantity display portion  39 . The residual quantity display portion  39  displays a quantity of the chemical solution currently stored in response to the signal. Here, the residual quantity display portion  39  and the liquid level sensor  51  correspond to the residual quantity detecting sensor of this invention. 
     The chemical supply unit  27  has at its top an attachment portion  53  to which the chemical cartridge  29  is attached. The attachment portion  53  formed at the top of the chemical supply unit  27  includes a recess  55  slightly larger than the outer shape of the insert portion  45  of the chemical cartridge  29 , and an inlet  57  formed on the bottom of the recess  55  and positioned corresponding to the nozzle portion  47 . 
     The insert portion  45  of the chemical cartridge  29  mentioned above is inserted into the attachment portion  53  to be in service. 
     The chemical cartridge  29  mentioned above is, for example, filled in advance under a clean environment with a hydrochloric acid solution produced by dissolving a hydrogen chloride gas in deionized water, filled in advance under a clean environment with an ammonia solution produced by dissolving an ammonia gas in deionized water, or filled in advance under a clean environment with a hydrofluoric acid solution produced by dissolving a hydrogen fluoride gas in deionized water. Thus, a treating liquid with high cleanliness can be produced, thereby avoiding reduction in cleanliness of the treating solution during use. 
     Next, description will be made of a cleaning treatment with the substrate cleaning apparatus mentioned above. Here, the chemical cartridge  29  filled with a hydrofluoric acid solution and the chemical cartridge  29  filled with a container with hydrochloric acid are attached to the attachment portions  53  of the chemical supply unit  27 . 
     The hydrofluoric acid solution from the chemical cartridge  29  is mixed to the deionized water with the deionized water being supplied to the supply pipe  17  at a specified flow rate from the deionized water source  19 , and is supplied to the inner tank  7  as a treating liquid. Subsequently, the substrates W move downward to a treatment position with the treating liquid overflowing the inner tank  7 . This state is then maintained for a predetermined time. Subsequently, supply of the hydrofluoric acid solution from the chemical cartridge  29  is stopped to perform cleaning with the deionized water. After elapse of a predetermined time, supply of the deionized water from the deionized water source  19  is stopped while the ozone water is supplied at a specified flow rate from the ozone water source  21 . This state is maintained for a predetermined time, and then the deionized water is supplied again only from the deionized water source  19  to perform cleaning with the deionized water. In addition, the hydrochloric acid solution is supplied at a specified flow rate from the chemical cartridge  29  storing the hydrochloric acid solution, and this state is maintained for a predetermined time. Subsequently, supply of the hydrochloric acid solution from the chemical cartridge  29  is stopped, and only the deionized water is supplied from the deionized water source  19  to perform cleaning with the deionized water. After finishing final cleaning with the deionized water, the substrates W in the treatment position are pulled up from the inner tank  7  to move into a standby position. 
     With the apparatus of this embodiment mentioned above, the chemical solution is mixed to the deionized water from the chemical cartridge  29  via the chemical supply unit  27  to produce the treating liquid. Then, the treating liquid is supplied to the treating tank  1  via the supply pipe  17 . The chemical cartridge  29  is not supplemented with the chemical solution through the supplementing line etc., and the chemical solution is not contaminated. As a result, cleanliness of the chemical solution can be kept high, and the substrates can be cleaned at a high clean level. 
     The chemical cartridge  29  also has a residual quantity display portion  39 . Thus a residual quantity of the chemical solution in chemical cartridge  29  can easily be recognized, and periodic replacement timing of the chemical cartridge  29  can also be recognized easily. In addition, the chemical cartridge  29  can control the flow rate by the nozzle portion  47 . Consequently, the chemical cartridge  29  can directly be attached to the supply pipe  17 , which can simplify the construction and thus can reduce apparatus cost. 
     EMBODIMENT 2  
     Description will be next given to Embodiment 2 of this invention with reference to the drawings.  FIG. 3  is a schematic view of a substrate treating apparatus according to Embodiment 2. The same elements as in Embodiment 1 mentioned above are represented by the same numerals, and the detailed description of such elements will be omitted. 
     The supply pipe  17  has a mixing valve  61 . The mixing valve  61  includes two or more branch pipes  63  through which a chemical solution is supplied. Each branch pipe  63  is provided with a control valve  65  for controlling a flow rate. Each branch pipe  63  has an attachment portion  53  at its end from which the chemical cartridge  29  is removable. 
     With the configuration in Embodiment 2, the control valve  65  controls a flow rate. Consequently, the chemical cartridge  29  may be attached to the attachment portion  53  with the nozzle portion  47  full open. Moreover, in Embodiment 2, treatment to the substrates W is performed as in Embodiment 1 mentioned above, but the control valve  65  controls the flow rate of the chemical solution. 
     According to the apparatus of this embodiments, it just needs to provide the attachment portion  53  on the branch pipe  63  of the mixing valve  61  included in the conventional apparatus. Consequently, the chemical cartridge system according to this invention is easily applicable to the conventional apparatus. 
     This invention is not limited to the foregoing embodiment, but may be modified as follows. 
     (1) In each embodiment mentioned above, a so-called batch type apparatus has been described as one example in which the treating tank  1  is provided as a treating unit and the substrates W are immersed therein. This invention is also applicable to apparatus of so-called single wafer type that perform treatment to one substrate W at a time. Specifically, there is included an apparatus that holds substrates in a horizontal attitude as a treating unit and that has a rotating member pivotal in a horizontal plane and supplies a treating liquid from a nozzle arranged above the rotating member to perform a cleaning treatment for every one substrate. 
     (2) This invention is not limited to the configuration of the chemical cartridge  29  in each embodiment mentioned above, but may have any shapes and structures removable from the chemical supply unit and filled with a chemical solution under a clean environment. 
     (3) In each embodiment mentioned above, a cleaning treatment has been described as one example with a hydrofluoric acid solution, deionized water, ozone water, deionized water, a hydrochloric acid solution, and deionized water. This invention is also applicable to cleaning treatments other than this cleaning treatment. 
     (4) Each embodiment mentioned above has been described with three chemical cartridges  29 . One chemical cartridge  29  or four or more chemical cartridges  29  may be applied to this invention.