Apparatus for and method of processing substrate

A substrate processing apparatus discharges a hydrofluoric acid solution from discharge nozzles toward grooves formed in side walls of an inner bath. The hydrofluoric acid solution discharged from the discharge nozzles impinges upon the grooves to diffuse, thereby moving toward a top portion of the inner bath in the form of low-speed uniform liquid flows. Thus, a metal component and foreign substances generated in the inner bath float up toward the top portion of the inner bath without being agitated within the inner bath, and are rapidly drained to an outer bath together with the hydrofluoric acid solution.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus for performing a cleaning process, an etching process and other processes upon substrates such as semiconductor substrates, glass substrates for a liquid crystal display device, glass substrates for a photomask and the like by dipping the substrates in a processing liquid.

2. Description of the Background Art

In the process of manufacturing substrates, a substrate processing apparatus is used which processes the substrates by dipping the substrates in a processing liquid stored in a processing bath.FIG. 18is a view showing an example of a background art substrate processing apparatus100. As shown inFIG. 18, the background art substrate processing apparatus100includes a processing bath110for storing a processing liquid therein, and causes the processing liquid to overflow from a top portion of the processing bath110while discharging the processing liquid from discharge nozzles113provided in a bottom portion of the processing bath110to supply the processing liquid to around substrates W, thereby processing the substrates W.

In particular, a substrate processing apparatus of what is called a one-bath type discharges a plurality of types of processing liquids such as an etchant, a cleaning liquid, deionized water and the like in sequential order from the discharge nozzles113. Such a substrate processing apparatus stores the plurality of types of processing liquids in sequential order within the processing bath110to thereby perform a plurality of types of processes in sequential order upon the substrates W.

As shown inFIG. 18, the discharge nozzles113in the background art substrate processing apparatus100are designed to discharge the processing liquid toward the substrates W within the processing bath110. Thus, the processing liquid discharged from the discharge nozzles113forms relatively high-speed liquid flows within the processing bath110and is agitated all over the inside of the processing bath110. Such a conventional form of discharge, however, is intended to agitate the processing liquid all over the inside of the processing bath110, and is not capable of efficiently draining a used processing liquid from the processing bath110to replace the used processing liquid with a new processing liquid.

In such a background art substrate processing apparatus100, foreign substances such as particles, if contained within the processing bath110, are also agitated together with the processing liquid within the processing bath110. Thus, the background art substrate processing apparatus100is not capable of rapidly remove the foreign substances contained within the processing bath110from the processing bath110. Such foreign substances are deposited onto the surfaces of the substrates W being processed to give rise to apprehensions about the contamination of the substrates W and about the processing failures of the substrates W. In particular, when an acid chemical liquid is used as the processing liquid or when substrates W having hydrophobic surfaces are used, the foreign substances such as particles are prone to adhere to the surfaces of the substrates W to make the above-mentioned problem more serious.

For the substrate processing apparatus of the one-bath type, it is desired in some cases to uniformly process the substrates W as in an etching process, and it is desired in other cases to efficiently replace a processing liquid stored within the processing bath with another processing liquid. For the uniform processing of the substrates W, it is desirable to form a relatively high-speed liquid flow within the processing bath, thereby making the concentration of the processing liquid stored within the processing bath uniform. For the efficient replacement of the processing liquid stored within the processing bath with another processing liquid, on the other hand, it is desirable to form a relatively low-speed liquid flow within the processing bath, thereby discharging the processing liquid in such a manner as to force the processing liquid outwardly from the top portion of the processing bath.

The background art substrate processing apparatus, however, is configured to discharge the processing liquid from the pair of discharge nozzles113toward the inside of the processing bath110, as described above. Because of such a configuration, it is difficult to form different liquid flows within the processing bath110depending on processing conditions. The background art substrate processing apparatus is not capable of satisfying both the requirement for improvements in processing uniformity of the processing liquid and the requirement for efficient replacement of the processing liquid stored within the processing bath with another processing liquid.

SUMMARY OF THE INVENTION

The present invention is intended for a substrate processing apparatus for processing a substrate by dipping the substrate in a processing liquid.

According to the present invention, the substrate processing apparatus comprises: a processing bath having a side wall and a bottom wall for storing the processing liquid therein; a first discharge part for discharging the processing liquid toward one of the side wall and the bottom wall within the processing bath; a drainage part for draining the processing liquid overflowing from a top portion of the processing bath; and a lifter for moving the substrate upwardly and downwardly between the inside of the processing bath and a position over the processing bath.

The processing liquid discharged from the first discharge part impinges upon the side wall or the bottom wall to diffuse, thereby moving toward the top portion of the processing bath in the form of low-speed uniform liquid flows. Thus, a metal component and foreign substances generated in the processing bath float up toward the top portion of the processing bath without being agitated within the processing bath, and are rapidly drained to the outside of the processing bath together with the processing liquid. Further, there is no need to complicate the structure of the first discharge part itself. This suppresses the manufacturing costs of the substrate processing apparatus.

Preferably, the first discharge part discharges the processing liquid toward a recessed portion formed in one of the side wall and the bottom wall.

The processing liquid diffused by the side wall or the bottom wall is moved toward a central portion of the processing bath. Thus, the low-speed uniform flows of processing liquid are formed well around the substrate dipped in the processing liquid.

Preferably, the first discharge part has a pair of discharge nozzles, and the pair of discharge nozzles discharge the processing liquid toward recessed portions formed in a pair of opposed side walls, respectively, of the processing bath.

The flows of processing liquid diffused by the pair of side walls are joined together near the central portion of the processing bath to move upwardly from near the central portion of the processing bath.

Preferably, the recessed portions are formed in lower end portions of the pair of opposed side walls, respectively.

The processing liquid is diffused near the bottom portion of the processing bath to form flows of processing liquid directed upwardly from the bottom portion of the processing bath well.

Preferably, each of the recessed portions is a groove of a V-shaped cross-sectional configuration opening to the inside of the processing bath.

The recessed portions are easily formed in the respective side walls of the processing bath. Further, the direction in which the processing liquid moves is easily determined by the inclination of tapered surfaces defining the groove of the V-shaped cross-sectional configuration.

Preferably, the groove of the V-shaped cross-sectional configuration is defined by a pair of tapered surfaces, and each of the pair of discharge nozzles discharges the processing liquid toward a lower one of the pair of tapered surfaces.

More processing liquid is moved toward the vicinity of the bottom portion of the processing bath.

Preferably, each of the recessed portions is a groove having the shape of a curved surface opening to the inside of the processing bath.

The direction in which the processing liquid moves is determined more appropriately.

Preferably, the substrate processing apparatus further comprises: a second discharge part for discharging the processing liquid toward the inside of the processing bath; and a controller for individually controlling the operation of the first discharge part and the operation of the second discharge part depending on the progress of processing, wherein the processing liquid discharged from the first discharge part impinges upon an inner wall surface of the processing bath to thereby form a liquid flow within the processing bath, the liquid flow being lower in speed than that of the processing liquid discharged from the second discharge part.

When it is desired to improve the uniformity of the processing with the processing liquid, the second discharge part is used to form relatively high-speed liquid flows within the processing bath, thereby making the concentration of the processing liquid within the processing bath uniform. When it is desired to efficiently replace the processing liquid within the processing bath with another processing liquid, the first discharge part is used to form relatively low-speed liquid flows within the processing bath, thereby accomplishing the efficient drainage of the processing liquid from the processing bath.

Preferably, the first discharge part discharges the processing liquid toward a recessed portion formed in the inner wall surface of the processing bath.

The processing liquid discharged from the first discharge part is moved well toward the inside of the processing bath.

Preferably, the second discharge part has a first nozzle disposed near a bottom portion of the processing bath, and a second nozzle disposed near the top portion of the processing bath, and the first discharge part has a third nozzle disposed above the first nozzle near the bottom portion of the processing bath.

The processing liquid is uniformly discharged from the second discharge part into the processing bath, and the processing liquid is discharged from the first discharge part toward the vicinity of the bottom portion of the processing bath.

Preferably, the first nozzle includes a pair of first nozzles disposed on opposite sides of a region in which the substrate is dipped in the processing liquid within the processing bath, the second nozzle includes a pair of second nozzles disposed on opposite sides of the region, and the third nozzle includes a pair of third nozzles disposed on opposite sides of the region.

Flows of processing liquid free of nonuniformity are formed near the substrate dipped in the processing liquid stored within the processing bath.

Preferably, the processing liquid includes an etchant for execution of an etching process on the substrate, and a non-etching liquid for execution of another process, and the controller causes the second discharge part to discharge the etchant when supplying the etchant to the inside of the processing bath.

The uniform concentration of the etchant component is achieved within the processing bath to allow the etching process to proceed uniformly on the main surface of the substrate.

Preferably, the substrate processing apparatus further comprises a measurement part for measuring one of the concentration of the component of the etchant contained in the processing liquid stored within the processing bath and the resistivity value of the processing liquid, wherein the controller causes the second discharge part to discharge the non-etching liquid when replacing the etchant stored within the processing bath with the non-etching liquid, and wherein the controller causes the second discharge part to stop discharging the non-etching liquid and causes the first discharge part to discharge the non-etching liquid when a measurement value obtained by the measurement part reaches a predetermined value.

While the etchant component remains in certain amounts within the processing bath, the second discharge part discharges the processing liquid to make the concentration of the etchant component uniform. After the etchant component is drained in certain amounts out of the processing bath, the first discharge part discharges the processing liquid to efficiently drain the remaining etchant component from the processing bath.

Preferably, when replacing the processing liquid stored within the processing bath with a second processing liquid, the controller causes the discharge of the second processing liquid from the second discharge part and the discharge of the second processing liquid from the first discharge part in an alternating manner.

The processing liquid is efficiently replaced while the component of the processing liquid remaining near the substrate is agitated.

The present invention is also intended for a method of processing a substrate by dipping the substrate in a processing liquid.

According to the present invention, the method comprises the steps of: a) discharging the processing liquid toward one of a side wall and a bottom wall of a processing bath within the processing bath; and b) dipping the substrate in the processing liquid stored within the processing bath.

The processing liquid discharged in the step a) impinges upon the side wall or the bottom wall of the processing bath to diffuse, thereby moving toward the top portion of the processing bath in the form of low-speed uniform liquid flows. Thus, foreign substances such as particles generated in the processing bath float up toward the top portion of the processing bath without being agitated within the processing bath, and are rapidly drained to the outside of the processing bath together with the processing liquid.

It is therefore an object of the present invention to provide an apparatus for and a method of processing a substrate which are capable of suppressing the agitation of a processing liquid within a processing bath to drain foreign substances such as particles out of the processing bath efficiently.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. First Preferred Embodiment

<1-1. Construction of Substrate Processing Apparatus>

FIG. 1is a vertical sectional view of a substrate processing apparatus1taken along a plane parallel to the main surfaces of substrates W according to a first preferred embodiment of the present invention. The construction of a control system and liquid supply and drainage systems included in the substrate processing apparatus1is also shown inFIG. 1.FIG. 2is a vertical sectional view of the substrate processing apparatus1taken along a plane perpendicular to the main surfaces of the substrates W. A common XYZ rectangular coordinate system is additionally shown inFIGS. 1 and 2for purposes of clarifying the positional relationship between components in the substrate processing apparatus1.

This substrate processing apparatus1is an apparatus which stores a hydrofluoric acid (HF) solution within a processing bath10and which performs an etching process on a plurality of substrates W by dipping the substrates W in the stored hydrofluoric acid solution. As shown inFIGS. 1 and 2, the substrate processing apparatus1principally includes the processing bath10for storing a hydrofluoric acid solution therein, a lifter20for transporting substrates W upwardly and downwardly while holding the substrates W, a hydrofluoric acid solution supply part30for supplying the hydrofluoric acid solution to the processing bath10, a hydrofluoric acid solution drainage part40for draining the hydrofluoric acid solution from the processing bath10, and a controller50for controlling the operations of the components in the substrate processing apparatus1.

The processing bath10is a reservoir made of a chemical-resistant material such as quartz. The processing bath10includes an inner bath11which stores the hydrofluoric acid solution therein to dip the substrates W therein, and an outer bath12formed in an outer peripheral portion of the inner bath11. The inner bath11includes a bottom wall111which is positioned under the substrates W when the substrates W are dipped in the hydrofluoric acid solution, and side walls112ato112dpositioned lateral to the substrates W. The inner bath11has an open top portion. A pair of discharge nozzles13for discharging the hydrofluoric acid solution are provided within the inner bath11. When the hydrofluoric acid solution is discharged from the discharge nozzles13, the hydrofluoric acid solution is stored within the inner bath11. The hydrofluoric acid solution stored up to the top portion of the inner bath11overflows from the top portion of the inner bath11into the outer bath12.

Of the four side walls112ato112dof the inner bath11, each of the pair of side walls112aand112bparallel to a direction in which the substrates W are arranged includes a bottom end portion (a portion in contact with the bottom wall111) configured to protrude outwardly. Thus, the inner surface of the bottom end portion of each of the side walls112aand112bis formed with a groove14extending in the direction in which the substrates W are arranged. The groove14has an upper tapered surface14aand a lower tapered surface14bwhich collectively form a groove of a V-shaped cross-sectional configuration opening to (or facing toward) the inside of the inner bath11.

The pair of discharge nozzles13are tubular members extending horizontally along the groove14formed in each of the side walls112aand112b,i.e., in the direction in which the substrates W are arranged. Each of the discharge nozzles13is formed with a plurality of discharge openings13aequally spaced apart from each other. The discharge openings13ain the discharge nozzles13are positioned to correspond to the space between adjacent ones of the substrates W and the outside of the opposite outermost ones of the substrates W within the processing bath10. The plurality of discharge openings13aare oriented so that the hydrofluoric acid solution is discharged toward the lower tapered surface14bof each of the grooves14. The hydrofluoric acid solution discharged through the plurality of discharge openings13aimpinges at right angles upon the lower tapered surface14bof each of the grooves14.

FIG. 3is a view showing flows of hydrofluoric acid solution when the hydrofluoric acid solution is additionally discharged from the discharge nozzles13, with the processing bath10filled with the hydrofluoric acid solution. As shown inFIG. 3, the hydrofluoric acid solution discharged from the discharge nozzles13impinges upon the lower tapered surfaces14bof the respective grooves14to turn toward the inside of the inner bath11while diffusing along the lower tapered surfaces14b. The hydrofluoric acid solution diffuses upon impingement upon the lower tapered surfaces14bto flow at decreasing speeds, and then turns upwardly from near the bottom of the inner bath11to move slowly upwardly. In this manner, the grooves14formed in the side walls112aand112bfunction as a flow direction controller which directs the flows of hydrofluoric acid solution toward the inside of the inner bath11, and also function to diffuse the hydrofluoric acid solution to decrease the speed of the flows thereof.

The lifter20is a transport mechanism for moving the substrates W upwardly and downwardly between the inside of the processing bath10and a position over the processing bath10while holding the substrates W. The lifter20includes three holding rods21extending in the direction in which the substrates W are arranged, and each of the holding rods21is formed with a plurality of holding grooves21a. The substrates W are held in parallel with each other in an upright position on the three holding rods21, with peripheral portions of the respective substrates W fitted in the holding grooves21a. The lifter20is connected to a driver22constructed by a known mechanism including a motor, a ball screw and the like combined together. When the driver22is operated, the lifter20moves upwardly and downwardly to transport the substrates W between a dipped position (the position of the substrates W shown inFIG. 1) which is inside the processing bath10and a raised position which is over the processing bath10.

The hydrofluoric acid solution supply part30is a piping system for supplying the hydrofluoric acid solution serving as a processing liquid to the above-mentioned discharge nozzles13. As shown inFIG. 1, the hydrofluoric acid solution supply part30includes a hydrofluoric acid solution supply source31, a pipe32, and an on-off valve33. The pipe32has an upstream end connected to the hydrofluoric acid solution supply source31, and the on-off valve33is interposed in the pipe32. The pipe32is divided at its downstream end into two branch pipes which in turn are connected to the pair of discharge nozzles13, respectively. Thus, when the on-off valve33is opened, the hydrofluoric acid solution is supplied from the hydrofluoric acid solution supply source31through the pipe32to the pair of discharge nozzles13, and is then discharged through the plurality of discharge openings13aof each of the discharge nozzles13into the inner bath11.

The hydrofluoric acid solution drainage part40is a piping system for collecting the hydrofluoric acid solution from the outer bath12to drain the collected hydrofluoric acid solution to a drainage line. As shown inFIG. 1, the hydrofluoric acid solution drainage part40includes a pipe41and an on-off valve42. The pipe41has an upstream end connected to the outer bath12, and a downstream end connected to the drainage line in a factory. The on-off valve42is interposed in the pipe41. Thus, when the on-off valve42is opened, the hydrofluoric acid solution is drained from the outer bath12through the pipe41to the drainage line.

The controller50is a computer device for controlling the operations of the components of the substrate processing apparatus1. The controller50is electrically connected to the driver22, the on-off valve33and the on-off valve42described above. The controller50brings the driver22, the on-off valve33and the on-off valve42described above into operation in accordance with a preinstalled program and various command entries to cause the processing of the substrates W to proceed.

<1-2. Operation of Substrate Processing Apparatus>

Next, the operation of the above-mentioned substrate processing apparatus1for the processing of a set of substrates W will be described with reference to the flow diagram ofFIG. 4. For the processing of the substrates W in the substrate processing apparatus1, the first step is to open the on-off valve33and the on-off valve42. This supplies the hydrofluoric acid solution from the hydrofluoric acid solution supply source31through the pipe32to the discharge nozzles13to discharge the hydrofluoric acid solution from the discharge nozzles13into the inner bath11(in Step S1). The hydrofluoric acid solution discharged from the discharge nozzles13is gradually stored within the inner bath11, and overflows from the top portion of the inner bath11into the outer bath12in due course.

Next, the substrates W transported from another apparatus by a predetermined transport mechanism are placed onto the lifter20waiting in the position over the processing bath10. After the substrates W are placed on the lifter20, the substrate processing apparatus1brings the driver22into operation to move the lifter20downwardly, thereby dipping the substrates W into the hydrofluoric acid solution stored within the processing bath10(in Step S2). When the substrates W are dipped in the hydrofluoric acid solution, the substrates W are subjected to an etching process by a hydrofluoric acid component in the hydrofluoric acid solution.

At this time, flows of hydrofluoric acid solution generally shown inFIG. 3are formed within the processing bath10. Specifically, the hydrofluoric acid solution discharged from the discharge nozzles13impinges upon the lower tapered surfaces14bof the respective grooves14to turn toward the substrates W along the lower tapered surfaces14bwhile diffusing and flowing at decreasing speeds. Then, the hydrofluoric acid solution the flows of which are joined together near a central bottom portion of the inner bath11moves slowly upwardly from near the bottom portion of the inner bath11to form liquid flows directed uniformly upwardly at a low speed around the substrates W.

As the etching process proceeds, a metal component dissolves from the surfaces of the substrates W into the hydrofluoric acid solution, and foreign substances such as particles and the like deposited on the surfaces of the substrates W are lifted off (or released from) the surfaces of the substrates W into the hydrofluoric acid solution. However, the liquid flows directed uniformly upwardly at a low speed are formed around the substrates W as mentioned above. Thus, the metal component and foreign substances contained in the hydrofluoric acid solution float up toward the top portion of the inner bath11without being agitated within the inner bath11, and are rapidly drained to the outer bath12together with the hydrofluoric acid solution. This prevents the metal component and foreign substances generated in the hydrofluoric acid solution from adhering to the surfaces of the substrates W again.

After the etching process for a predetermined time period, the substrate processing apparatus1brings the driver22into operation to move the lifter20upwardly, thereby lifting the substrates W out of the hydrofluoric acid solution stored within the inner bath11(in Step S3). Thereafter, the substrates W are transferred from the lifter20to a predetermined transport device, and are then transported to an apparatus for performing the subsequent process by the predetermined transport device. The substrate processing apparatus1closes the on-off valve33and the on-off valve42. This stops the discharge of the hydrofluoric acid solution from the discharge nozzles13and the drainage of the hydrofluoric acid solution to the hydrofluoric acid solution drainage part40(in Step S4). Thus, a series of processes of the set of substrates W are completed.

In this manner, the substrate processing apparatus1according to the first preferred embodiment discharges the hydrofluoric acid solution from the discharge nozzles13toward the grooves14formed in the side walls112aand112bof the inner bath11. The hydrofluoric acid solution discharged from the discharge nozzles13impinges upon the grooves14to diffuse, thereby moving toward the top portion of the inner bath11in the form of low-speed uniform liquid flows. Thus, the metal component and foreign substances generated in the inner bath11float up toward the top portion of the inner bath11without being agitated within the inner bath11, and are rapidly drained to the outer bath12together with the hydrofluoric acid solution.

The substrate processing apparatus1according to the first preferred embodiment forms the low-speed uniform flows of hydrofluoric acid solution within the inner bath11to accomplish the efficient drainage of the hydrofluoric acid solution out of the inner bath11and the efficient supply of a new hydrofluoric acid solution into the inner bath11. In other words, the substrate processing apparatus1is capable of efficiently replacing the used hydrofluoric acid solution within the inner bath11with a new hydrofluoric acid solution during the etching process to apply a constantly clean hydrofluoric acid solution to the substrates W. This reduces the time required for the etching process.

If the diameter of the discharge openings13aof the discharge nozzles13is increased, there arises a significant difference in discharge pressure of the hydrofluoric acid solution between upstream ones of the discharge openings13aand downstream ones of the discharge openings13a. The substrate processing apparatus1according to the first preferred embodiment, however, does not decrease the speed of the flows of hydrofluoric acid solution by increasing the diameter of the discharge openings13abut decreases the speed of the flows of hydrofluoric acid solution by causing the hydrofluoric acid solution to impinge upon the side walls112aand112bof the inner bath11. This achieves the decrease in the speed of the flows of hydrofluoric acid solution while preventing the significant difference in discharge pressure of the hydrofluoric acid solution between upstream ones of the discharge openings13aand downstream ones of the discharge openings13a.

Further, the substrate processing apparatus1according to the first preferred embodiment achieves the decrease in the speed of the flows of hydrofluoric acid solution without complicating the construction of the discharge nozzles13themselves. This improves the replacement efficiency of the hydrofluoric acid solution while suppressing the increase in manufacturing costs of the substrate processing apparatus1including the discharge nozzles13.

According to the first preferred embodiment, the discharge nozzles13discharge the hydrofluoric acid solution toward the lower tapered surfaces14bof the grooves14formed in the side walls112aand112bof the inner bath11. This allows a greater amount of diffused hydrofluoric acid solution to move toward the vicinity of the bottom portion of the inner bath11, thereby further improving the replacement efficiency of the hydrofluoric acid solution.

Although the discharge nozzles13according to the first preferred embodiment described above discharge the hydrofluoric acid solution toward the lower tapered surfaces14bof the grooves14, the discharge nozzles13may discharge the hydrofluoric acid solution toward other portions of the grooves14. As shown inFIG. 5, for example, the hydrofluoric acid solution may be discharged from the discharge nozzles13toward a boundary between the upper and lower tapered surfaces14aand14b.

Each of the grooves14according to the first preferred embodiment described above is a groove of a V-shaped cross-sectional configuration defined by the pair of tapered surfaces14aand14b. The configuration of the grooves14may be a curved surface (semicylindrical) as shown inFIGS. 6 and 7. It is only necessary that a recessed portion having a configuration for the flow direction control of the discharged hydrofluoric acid solution be formed in a position opposed to the plurality of discharge openings13aof the discharge nozzles13. When the configuration of the grooves14is a curved surface, the discharge nozzles13may be disposed slightly above the central axis of each of the grooves14to discharge the hydrofluoric acid solution toward an upper portion of each of the grooves14, as shown inFIG. 7. This allows the hydrofluoric acid solution discharged from the discharge nozzles13to move along the curved surface of each of the grooves14to the vicinity of the bottom portion, thereby forming the flows of hydrofluoric acid solution directed upwardly from the bottom portion of the inner bath11well.

Although the grooves14are formed in the bottom end portions of the side walls112aand112b,respectively, of the inner bath11according to the first preferred embodiment described above, the grooves14may be formed in a position slightly shifted toward upper portions of the side walls112aand112b. Alternatively, the grooves14may be formed in the bottom wall111of the inner bath11, as shown inFIG. 8.

The substrate processing apparatus according to the present invention may be designed such that the hydrofluoric acid solution is discharged from the discharge nozzles13toward the inner surface of the inner bath11in which the grooves14are dispensed with. As shown inFIG. 9, for example, the hydrofluoric acid solution may be discharged from the discharge nozzles13toward the side walls112aand112bof the inner bath11. The substrate processing apparatus1of such a configuration is capable of diffusing the hydrofluoric acid solution to decrease the speed of the flows thereof, thereby forming the low-speed flows of hydrofluoric acid solution around the substrates W. When the hydrofluoric acid solution is discharged toward the side walls112aand112b,it is desirable that the hydrofluoric acid solution is directed at right angles toward the side walls112aand112b,as shown inFIG. 9. This prevents the hydrofluoric acid solution (the hydrofluoric acid solution containing the metal component and foreign substances) near the top portion of the inner bath11from being carried in the discharged liquid flows toward the bottom portion of the inner bath11.

Although the hydrofluoric acid solution is used as the processing liquid according to the first preferred embodiment described above, the substrate processing apparatus according to the present invention may use other processing liquids to process the substrates W. Examples of the processing liquid used herein may include an SC-1 (standard cleaning 1; NH4OH—H2O2—H2O) solution, an SC-2 (standard cleaning 2; HCl—H2O2—H2O) solution, Caro's acid, deionized water and the like. The present invention is applicable not only to a substrate processing apparatus which processes semiconductor substrates but also to substrate processing apparatuses which process various substrates such as glass substrates for a liquid crystal display device, glass substrates for a photomask and the like.

2. Second Preferred Embodiment

<2-1. Construction of Substrate Processing Apparatus>

FIG. 10is a vertical sectional view of a substrate processing apparatus201taken along a plane parallel to the main surfaces of substrates W according to a second preferred embodiment of the present invention.FIG. 11is a vertical sectional view of the substrate processing apparatus201taken along a plane perpendicular to the main surfaces of the substrate W. A common XYZ rectangular coordinate system is additionally shown inFIGS. 10 and 11for purposes of clarifying the positional relationship between components in the substrate processing apparatus201.FIG. 12shows the construction of a control system and liquid supply and drainage systems for the substrate processing apparatus201. The construction of the substrate processing apparatus201will be described below with reference toFIGS. 10 to 12.

This substrate processing apparatus201is an apparatus which stores deionized water, dilute hydrofluoric acid, deionized water, the SC-1 solution, deionized water, the SC-2 solution, and deionized water (these liquids and a mixture of these liquids are collectively referred to as a “processing liquid” hereinafter) in the order named within a processing bath210, and which performs a cleaning process, an etching process and the like on a plurality of substrates W by dipping the substrates W in the processing liquid. As shown inFIGS. 10 to 12, the substrate processing apparatus201principally includes the processing bath210for storing the processing liquid therein, a lifter220for transporting substrates W upwardly and downwardly while holding the substrates W, a processing liquid supply part230for supplying the processing liquid to the processing bath210, a processing liquid drainage part240for draining the processing liquid from the processing bath210, and a controller250for controlling the operations of components in the substrate processing apparatus201.

The processing bath210is a reservoir made of quartz or a chemical-resistant resin. The processing bath210includes an inner bath211which stores the processing liquid therein to dip the substrates W therein, and an outer bath212formed in an outer peripheral portion of the inner bath211. The inner bath211includes a bottom wall311which is positioned under the substrates W when the substrates W are dipped in the processing liquid, and side walls312ato312dpositioned lateral to the substrates W. The inner bath211has an open top portion.

Four discharge nozzles331,332,341and342for discharging the processing liquid toward the inside of the inner bath211and two discharge nozzles351and352for discharging the processing liquid toward the side walls312aand312bof the inner bath211are provided within the inner bath211. The discharge nozzles331,332,341,342,351and352are hollow tubular members extending horizontally in the direction in which the substrates W are arranged. Each of the discharge nozzles331,332,341,342,351and352is formed with a plurality of discharge openings equally spaced apart from each other depending on the discharge direction thereof.

The discharge nozzles331and332are disposed near the top portion of the inner bath211(at a position higher than the center of the substrates W dipped in the processing liquid), and are fixed horizontally along the pair of side walls312aand312bopposed to each other with the substrates W therebetween. The discharge nozzles331and332are formed with a plurality of discharge openings331aand332awhich discharge the processing liquid slightly downwardly toward the inside of the inner bath211. The positions of the plurality of discharge openings331aand332aalong the X-axis correspond to the space between adjacent ones of the substrates W and the outside of the opposite outermost ones of the substrates W within the processing bath210. When the processing liquid is supplied to the discharge nozzles331and332, the processing liquid is discharged through the plurality of discharge openings331aand332aof the discharge nozzles331and332toward the dipped position of the substrates W within the inner bath211.

The discharge nozzles341and342are disposed near the bottom portion of the inner bath211(at a position lower than the center of the substrates W dipped in the processing liquid), and are fixed horizontally along the pair of side walls312aand312bopposed to each other with the substrates W therebetween. The discharge nozzles341and342are formed with a plurality of discharge openings341aand342awhich discharge the processing liquid slightly upwardly toward the inside of the inner bath211and a plurality of discharge openings341band342bwhich discharge the processing liquid along the bottom wall311toward the inside of the inner bath211. The positions of the plurality of discharge openings341a,341b,342aand342balong the X-axis correspond to the space between adjacent ones of the substrates W and the outside of the opposite outermost ones of the substrates W within the processing bath210. When the processing liquid is supplied to the discharge nozzles341and342, the processing liquid is discharged through the plurality of discharge openings341aand342aof the discharge nozzles341and342toward the dipped position of the substrates W within the inner bath211, and is discharged through the plurality of discharge openings341band342bof the discharge nozzles341and342toward the central position of the bottom portion of the inner bath211.

The discharge nozzles351and352are disposed above the discharge nozzles341and342near the bottom portion of the inner bath211, and are fixed horizontally along the pair of side walls312aand312bopposed to each other with the substrates W therebetween. The discharge nozzles351and352are formed with a plurality of discharge openings351a,351b,352aand352bwhich discharge the processing liquid toward grooves216formed respectively in the pair of side walls312aand312b. Each of the grooves216has an upper tapered surface216aand a lower tapered surface216bwhich collectively form a groove of a V-shaped cross-sectional configuration opening to (or facing toward) the inside of the inner bath211. The discharge openings351aand the discharge openings352aare oriented toward the upper tapered surfaces216aof the respective grooves216, and the discharge openings351band the discharge openings352bare oriented toward the lower tapered surfaces216bof the respective grooves216. The positions of the plurality of discharge openings351a,351b,352aand352balong the X-axis correspond to the space between adjacent ones of the substrates W and the outside of the opposite outermost ones of the substrates W within the processing bath210. When the processing liquid is supplied to the discharge nozzles351and352, the processing liquid is discharged through the plurality of discharge openings351aand352aof the discharge nozzles351and352toward the upper tapered surfaces216aof the respective grooves216, and is discharged through the plurality of discharge openings351band352bof the discharge nozzles351and352toward the lower tapered surfaces216bof the respective grooves216.

The processing liquid discharged from the discharge nozzles351and352impinges upon the upper and lower tapered surfaces216aand216bof the grooves216to turn toward the inside of the inner bath211while diffusing along the upper and lower tapered surfaces216aand216b. The diffused processing liquid forms wide low-speed liquid flows which in turn reach the central position of the bottom portion of the inner bath211and further turn toward the top portion of the inner bath211to move slowly upwardly. In this manner, the grooves216formed in the side walls312aand312bfunction as a flow direction controller which directs the flows of processing liquid discharged from the discharge nozzles351and352toward the inside of the inner bath211, and also function to diffuse the processing liquid discharged from the discharge nozzles351and352to decrease the speed of the flows thereof.

The substrate processing apparatus201discharges the processing liquid from the discharge nozzles331,332,341,342,351and352toward the inside of the inner bath211to store the processing liquid within the inner bath211. The processing liquid stored up to the top portion of the inner bath211overflows from the top portion of the inner bath211into the outer bath212.

A resistivity meter217for measuring the resistivity value of the processing liquid is provided within the inner bath211. The resistivity meter217includes a pair of metal electrodes, and measures an electrical resistance between the metal electrodes to measure the resistivity value of the processing liquid. During the process of replacing the processing liquid to be described later, the resistivity meter217measures the resistivity value of the processing liquid stored within the processing bath210to send information about the obtained resistivity value to the controller250. The resistivity meter217may incorporate a temperature sensor in the metal electrodes to send an equivalent of the resistivity value at a predetermined temperature to the controller250.

The lifter220is a transport mechanism for moving the substrates W upwardly and downwardly between the inside of the inner bath211and a position over the processing bath210while holding the substrates W. The lifter220includes three holding rods221extending in the direction in which the substrates W are arranged, and each of the holding rods221is formed with a plurality of holding grooves221a. The substrates W are held in parallel with each other in an upright position on the three holding rods221, with peripheral portions of the respective substrates W fitted in the holding grooves221a. The lifter220is connected to a driver222constructed by a known mechanism including a motor, a ball screw and the like combined together. When the driver222is operated, the lifter220moves upwardly and downwardly to transport the substrates W between the dipped position (the position of the substrates W shown inFIGS. 10 and 11) which is inside the inner bath211and the raised position which is over the processing bath210.

The processing liquid supply part230is a piping system for supplying the processing liquid to the above-mentioned discharge nozzles331,332,341,342,351and352. As shown inFIG. 12, the processing liquid supply part230includes a processing liquid supply source231, a main pipe232, branch pipes233aand233b,and on-off valves234aand234b.

The processing liquid supply source231includes a hydrofluoric acid supply source511, an ammonium hydroxide supply source512, a hydrochloric acid supply source513, a hydrogen peroxide supply source514, and a deionized water supply source515. The hydrofluoric acid supply source511, the ammonium hydroxide supply source512, the hydrochloric acid supply source513, the hydrogen peroxide supply source514, and the deionized water supply source515are fluidly connected to the main pipe232through on-off valves235a,235b,235c,235dand235e,respectively. The main pipe232has a downstream end connected the branch pipes233aand233b. The on-off valves234aand234bare interposed in the branch pipes233aand233b,respectively. The branch pipe233ais divided at its downstream end into four sub-branch pipes which in turn are connected to the discharge nozzles331,332,341and342, respectively. The branch pipe233bis divided at its downstream end into two sub-branch pipes which in turn are connected to the discharge nozzles351and352, respectively.

When the on-off valves235b,235cand235dare closed and the on-off valves235aand235eare opened in the processing liquid supply source231, hydrofluoric acid from the hydrofluoric acid supply source511and deionized water from the deionized water supply source515are mixed together in predetermined proportions to form dilute hydrofluoric acid. The generated dilute hydrofluoric acid is supplied to the main pipe232. The dilute hydrofluoric acid functions as an etchant for the execution of an etching process on substrates W.

When the on-off valves235aand235care closed and the on-off valves235b,235dand235eare opened in the processing liquid supply source231, ammonium hydroxide from the ammonium hydroxide supply source512, hydrogen peroxide from the hydrogen peroxide supply source514, and deionized water from the deionized water supply source515are mixed together in predetermined proportions to form the SC-1 solution. The generated SC-1 solution is supplied to the main pipe232. The SC-1 solution functions as a cleaning liquid for the execution of a liquid chemical cleaning process (a non-etching process) on substrates W.

When the on-off valves235aand235bare closed and the on-off valves235c,235dand235eare opened in the processing liquid supply source231, hydrochloric acid from the hydrochloric acid supply source513, hydrogen peroxide from the hydrogen peroxide supply source514, and deionized water from the deionized water supply source515are mixed together in predetermined proportions to form the SC-2 solution. The generated SC-2 solution is supplied to the main pipe232. The SC-2 solution functions as a cleaning liquid for the execution of a liquid chemical cleaning process (a non-etching process) on substrates W.

When the on-off valves235a,235b,235cand235dare closed and the on-off valve235eis opened in the processing liquid supply source231, only deionized water from the deionized water supply source515is supplied to the main pipe232.

In this manner, the dilute hydrofluoric acid, SC-1 solution, SC-2 solution or deionized water supplied from the processing liquid supply source231is supplied to the branch pipe233aor the branch pipe233bby changing the on-off valves234aand234bbetween the “on” and “off” states. Specifically, when the on-off valve234bis closed and the on-off valve234ais opened, the dilute hydrofluoric acid, SC-1 solution, SC-2 solution or deionized water supplied from the processing liquid supply source231is fed through the branch pipe233ato the discharge nozzles331,332,341and342, and is discharged through the plurality of discharge openings331a,332a,341a,341b,342aand342bof the discharge nozzles331,332,341and342into the inner bath211. When the on-off valve234ais closed and the on-off valve234bis opened, the dilute hydrofluoric acid, SC-1 solution, SC-2 solution or deionized water supplied from the processing liquid supply source231is fed through the branch pipe233bto the discharge nozzles351and352, and is discharged through the plurality of discharge openings351a,351b,352aand352bof the discharge nozzles351and352into the inner bath211.

The processing liquid drainage part240is a piping system for collecting the processing liquid from the outer bath212to drain the collected processing liquid to a drainage line. As shown inFIG. 12, the processing liquid drainage part240includes a pipe241. The pipe241has an upstream end connected to the outer bath212, and a downstream end connected to the drainage line in a factory. Thus, the processing liquid overflowing into the outer bath212is drained from the outer bath212through the pipe241to the drainage line.

The controller250is a computer device for controlling the operations of the components of the substrate processing apparatus201. The controller250is electrically connected to the resistivity meter217, the driver222, and the on-off valves234a,234b,235a,235b,235c,235dand235edescribed above. The controller250receives the measurement value from the resistivity meter217to control the operations of the driver222and the on-off valves234a,234b,235a,235b,235c,235dand235edescribed above in accordance with the above-mentioned measurement value and a preinstalled program, thereby causing the processing of the substrates W to proceed.

<2-2. Operation of Substrate Processing Apparatus>

Next, the operation of the above-mentioned substrate processing apparatus201for the processing of a set of substrates W will be described with reference to the flow diagram ofFIG. 13.

For the processing of the substrates W in the substrate processing apparatus201, the first step is to supply deionized water from the processing liquid supply source231, with the on-off valve234aclosed and the on-off valve234bopen. The deionized water supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233binto the discharge nozzles351and352, and is then discharged from the discharge nozzles351and352into the inner bath211. Thus, the deionized water is stored gradually within the inner bath211, and overflows from the top portion of the inner bath211into the outer bath212in due course (in Step S201). The deionized water overflowing into the outer bath212is drained through the pipe241to the drainage line.

Next, the substrates W transported from another apparatus by a predetermined transport mechanism are placed onto the lifter220waiting in the position over the processing bath210. After the substrates W are placed on the lifter220, the substrate processing apparatus201brings the driver222into operation to move the lifter220downwardly, thereby dipping the substrates W into the deionized water stored within the inner bath211(in Step S202).

Subsequently, the substrate processing apparatus201closes the on-off valve234b,and opens the on-off valve234a. Then, dilute hydrofluoric acid is supplied from the processing liquid supply source231in place of deionized water. The dilute hydrofluoric acid supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233ainto the discharge nozzles331,332,341and342, and is then discharged from the discharge nozzles331,332,341and342into the inner bath211. The substrate processing apparatus201causes the processing liquid to overflow from the top portion of the inner bath211into the outer bath212while supplying the dilute hydrofluoric acid into the inner bath211, thereby gradually replacing the deionized water with the dilute hydrofluoric acid within the inner bath211(in Step S203).

When the replacement of the deionized water with the dilute hydrofluoric acid starts, the etching process of the substrates W is started by a hydrofluoric acid component supplied to near the main surfaces of the substrates W. The dilute hydrofluoric acid is discharged from the discharge nozzles331,332,341and342toward the inside of the inner bath211to form relatively high-speed liquid flows within the inner bath211, as shown inFIG. 15. This causes the hydrofluoric acid component supplied to the inside of the inner bath211to be agitated widely all over the inside of the inner bath211. Thus, in the source of the replacement of the deionized water with the dilute hydrofluoric acid, the concentration of the hydrofluoric acid component is always made uniform within the inner bath211, and the uniform etching process is performed on the entire major surfaces of the substrates W.

After the completion of the replacement of the deionized water with the dilute hydrofluoric acid, the substrate processing apparatus201continues the discharge of the dilute hydrofluoric acid from the discharge nozzles331,332,341and342as required. The substrates W dipped in the dilute hydrofluoric acid stored in the inner bath211continue to be subjected to the etching process (in Step S204).

Next, the substrate processing apparatus201replaces the dilute hydrofluoric acid with deionized water within the inner bath211(in step S205). A detailed procedure for the process of replacing the dilute hydrofluoric acid with the deionized water in Step S205will be described with reference toFIG. 14.

For the replacement of the dilute hydrofluoric acid with the deionized water within the inner bath211, the substrate processing apparatus201initially supplies deionized water from the processing liquid supply source231, with the on-off valve234bmaintained closed and the on-off valve234amaintained open. The deionized water supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233ainto the discharge nozzles331,332,341and342, and is then discharged from the discharge nozzles331,332,341and342into the inner bath211(in Step S251). The substrate processing apparatus201causes the processing liquid to overflow from the top portion of the inner bath211into the outer bath212while supplying the deionized water into the inner bath211, thereby gradually replacing the dilute hydrofluoric acid with the deionized water within the inner bath211.

In the early stage of the replacement of the dilute hydrofluoric acid with the deionized water, the hydrofluoric acid component remaining within the inner bath211causes the etching process of the substrates W to still proceed. In this early stage of the replacement, the substrate processing apparatus201discharges the deionized water from the discharge nozzles331,332,341and342to flow relatively high-speed liquid flows within the inner bath211, as shown inFIG. 15. This causes the hydrofluoric acid component remaining within the inner bath211to be agitated widely all over the inside of the inner bath211, thereby accomplishing the uniform etching process on the entire surfaces of the substrates W.

As the replacement of the dilute hydrofluoric acid with the deionized water proceeds, the concentration of the hydrofluoric acid component in the processing liquid stored within the inner bath211decreases gradually. As the concentration of the hydrofluoric acid component decreases, the measurement value obtained by the resistivity meter217increases gradually. The substrate processing apparatus201receives the measurement value obtained by the resistivity meter217to continuously monitor whether or not the measurement value reaches a predetermined reference value r1(in Step S252). The reference value r1used herein is a resistivity value of the processing liquid such that the hydrofluoric acid component in the processing liquid no longer causes the etching process of the substrates W to substantially proceed, and is set in the controller250based on a previous experiment and the like.

When the measurement value obtained by the resistivity meter217reaches the above-mentioned reference value r1, the substrate processing apparatus201closes the on-off valve234aand opens the on-off valve234b. This stops the discharge of the deionized water from the discharge nozzles331,332,341and342, and starts the discharge of the deionized water from the discharge nozzles351and352(in Step S253).

The deionized water discharged from the discharge nozzles351and352impinges upon the grooves216formed in the side walls312aand312bof the inner bath211to diffuse, thereby turning toward the inside of the inner bath211. Thus, low-speed uniform liquid flows directed upwardly from near the bottom portion of the inner bath211are formed within the inner bath211, as shown inFIG. 16. Accordingly, the hydrofluoric acid component remaining within the inner bath211is drained from the top portion of the inner bath211into the outer bath212in such a manner as to be forced out by the low-speed liquid flows of deionized water. The replacement of the dilute hydrofluoric acid with the deionized water efficiently proceeds within the inner bath211.

The substrate processing apparatus201continues to receive the measurement value obtained by the resistivity meter217to continuously monitor whether or not the measurement value reaches a predetermined reference value r2(in Step S253). The reference value r2used herein is a resistivity value of the processing liquid such that the hydrofluoric acid component in the processing liquid is judged to be almost completely drained and be almost completely replaced with the deionized water within the inner bath211, and is previously set in the controller250. When the resistivity value obtained by the resistivity meter217reaches the reference value r2, the procedure proceeds to the subsequent step, i.e., Step S206.

Referring again toFIG. 13, the substrate processing apparatus201continues the discharge of the deionized water from the discharge nozzles351and352as required after the measurement value obtained by the resistivity meter217reaches the above-mentioned reference value r2. The substrates W dipped in the deionized water stored in the inner bath211are subjected to a rinsing process with the deionized water (in Step S206).

Next, the substrate processing apparatus201supplies the SC-1 solution from the processing liquid supply source231, with the on-off valve234amaintained closed and the on-off valve234bmaintained open. The SC-1 solution supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233binto the discharge nozzles351and352, and is then discharged from the discharge nozzles351and352into the inner bath211. The substrate processing apparatus201causes the processing liquid to overflow from the top portion of the inner bath211into the outer bath212while supplying the SC-1 solution into the inner bath211, thereby gradually replacing the deionized water with the SC-1 solution within the inner bath211(in Step S207).

The SC-1 solution discharged from the discharge nozzles351and352impinges upon the grooves216formed in the side walls312aand312bof the inner bath211to diffuse, thereby turning toward the inside of the inner bath211. Thus, low-speed uniform liquid flows directed upwardly from near the bottom portion of the inner bath211are formed within the inner bath211, as shown inFIG. 16. Accordingly, the deionized water within the inner bath211is drained from the top portion of the inner bath211into the outer bath212in such a manner as to be forced out by the low-speed liquid flows of SC-1 solution. The replacement of the deionized water with the SC-1 solution efficiently proceeds within the inner bath211.

The substrate processing apparatus201continues the discharge of the SC-1 solution from the discharge nozzles351and352as required after the replacement of the deionized water with the SC-1 solution is completed. The substrates W dipped in the SC-1 solution stored in the inner bath211are subjected to the liquid chemical cleaning process with the SC-1 solution (in Step S208).

Next, the substrate processing apparatus201supplies deionized water from the processing liquid supply source231, with the on-off valve234amaintained closed and the on-off valve234bmaintained open. The deionized water supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233binto the discharge nozzles351and352, and is then discharged from the discharge nozzles351and352into the inner bath211. The substrate processing apparatus201causes the processing liquid to overflow from the top portion of the inner bath211into the outer bath212while supplying the deionized water into the inner bath211, thereby gradually replacing the SC-1 solution with the deionized water within the inner bath211(in Step S209).

The deionized water discharged from the discharge nozzles351and352impinges upon the grooves216formed in the side walls312aand312bof the inner bath211to diffuse, thereby turning toward the inside of the inner bath211. Thus, low-speed uniform liquid flows directed upwardly from near the bottom portion of the inner bath211are formed within the inner bath211, as shown inFIG. 16. Accordingly, the SC-1 solution within the inner bath211is drained from the top portion of the inner bath211into the outer bath212in such a manner as to be forced out by the low-speed liquid flows of deionized water. The replacement of the SC-1 solution with the deionized water efficiently proceeds within the inner bath211.

The substrate processing apparatus201continues the discharge of the deionized water from the discharge nozzles351and352as required after the replacement of the SC-1 solution with the deionized water is completed. The substrates W dipped in the deionized water stored in the inner bath211are subjected to the rinsing process with the deionized water (in Step S210).

Next, the substrate processing apparatus201supplies the SC-2 solution from the processing liquid supply source231, with the on-off valve234amaintained closed and the on-off valve234bmaintained open. The SC-2 solution supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233binto the discharge nozzles351and352, and is then discharged from the discharge nozzles351and352into the inner bath211. The substrate processing apparatus201causes the processing liquid to overflow from the top portion of the inner bath211into the outer bath212while supplying the SC-2 solution into the inner bath211, thereby gradually replacing the deionized water with the SC-2 solution within the inner bath211(in Step S211).

The SC-2 solution discharged from the discharge nozzles351and352impinges upon the grooves216formed in the side walls312aand312bof the inner bath211to diffuse, thereby turning toward the inside of the inner bath211. Thus, low-speed uniform liquid flows directed upwardly from near the bottom portion of the inner bath211are formed within the inner bath211, as shown inFIG. 16. Accordingly, the deionized water within the inner bath211is drained from the top portion of the inner bath211into the outer bath212in such a manner as to be forced out by the low-speed liquid flows of SC-2 solution. The replacement of the deionized water with the SC-2 solution efficiently proceeds within the inner bath211.

The substrate processing apparatus201continues the discharge of the SC-2 solution from the discharge nozzles351and352as required after the replacement of the deionized water with the SC-2 solution is completed. The substrates W dipped in the SC-2 solution stored in the inner bath211are subjected to the liquid chemical cleaning process with the SC-2 solution (in Step S212).

Next, the substrate processing apparatus201supplies deionized water from the processing liquid supply source231, with the on-off valve234amaintained closed and the on-off valve234bmaintained open. The deionized water supplied from the processing liquid supply source231flows through the main pipe232and the branch pipe233binto the discharge nozzles351and352, and is then discharged from the discharge nozzles351and352into the inner bath211. The substrate processing apparatus201causes the processing liquid to overflow from the top portion of the inner bath211into the outer bath212while supplying the deionized water into the inner bath211, thereby gradually replacing the SC-2 solution with the deionized water within the inner bath211(in Step S213).

The deionized water discharged from the discharge nozzles351and352impinges upon the grooves216formed in the side walls312aand312bof the inner bath211to diffuse, thereby turning toward the inside of the inner bath211. Thus, low-speed uniform liquid flows directed upwardly from near the bottom portion of the inner bath211are formed within the inner bath211, as shown inFIG. 16. Accordingly, the SC-2 solution within the inner bath211is drained from the top portion of the inner bath211into the outer bath212in such a manner as to be forced out by the low-speed liquid flows of deionized water. The replacement of the SC-2 solution with the deionized water efficiently proceeds within the inner bath211.

The substrate processing apparatus201continues the discharge of the deionized water from the discharge nozzles351and352as required after the replacement of the SC-2 solution with the deionized water is completed. The substrates W dipped in the deionized water stored in the inner bath211are subjected to the rinsing process with the deionized water (in Step S214).

Thereafter, the substrate processing apparatus201brings the driver222into operation to move the lifter220upwardly, thereby lifting the substrates W out of the inner bath211(in Step S215). Thus, the substrate processing apparatus201completes a series of processes of the set of substrates W.

When it is desired to cause the etching process to proceed uniformly within the inner bath211(in Steps S202to S252described above), the substrate processing apparatus201according to the second preferred embodiment discharges the processing liquid from the discharge nozzles331,332,341and342to form relatively high-speed liquid flows within the inner bath211. This causes the hydrofluoric acid component to be agitated within the inner bath211, thereby making the concentration of the hydrofluoric acid component uniform. When it is desired to efficiently replace the processing liquid stored within the inner bath211(in Steps S253to S214described above), the substrate processing apparatus201according to the second preferred embodiment discharges the processing liquid from the discharge nozzles351and352to form relatively low-speed liquid flows within the inner bath211. This accomplish the efficient drainage of the processing liquid from the inner bath211. In this manner, the substrate processing apparatus201according to the second preferred embodiment uses the discharge nozzles331,332,341and342and the discharge nozzles351and352properly depending on processing conditions to thereby satisfy both the requirement for uniform processing within the inner bath211and the requirement for efficient replacement of the processing liquid stored within the inner bath211.

Although the deionized water is discharged only from the discharge nozzles351and352in Step S253described above, the operation in Step S253may be replaced with the operation in Steps S731to S733shown inFIG. 17. Specifically, after the measurement value obtained by the resistivity meter217reaches the reference value r1, the discharge of deionized water from the discharge nozzles351and352(in Step S731), the discharge of deionized water from the discharge nozzles331,332,341and342(in Step S732) and the discharge of deionized water from the discharge nozzles351and352(in Step S733) may be performed in order.

The execution of the discharge of deionized water from the discharge nozzles351and352and the discharge of deionized water from the discharge nozzles331,332,341and342in an alternating manner allows the hydrofluoric acid component remaining near the surfaces of the substrates W and the surfaces of the members of the lifter220to be efficiently drained while allowing the hydrofluoric acid component to be agitated by the deionized water discharged from the discharge nozzles331,332,341and342. Each of the discharge of deionized water from the discharge nozzles351and352and the discharge of deionized water from the discharge nozzles331,332,341and342may be performed, for example, for on the order of 10 to 20 seconds, and the number of repetitions thereof is not limited to that illustrated in the instance ofFIG. 17. For good completion of the replacement of the dilute hydrofluoric acid with the deionized water, it is desirable that the last process is the discharge of deionized water from the discharge nozzles351and352. In Steps S206to S214subsequent thereto, the discharge of the processing liquid from the discharge nozzles351and352and the discharge of the processing liquid from the discharge nozzles331,332,341and342may be similarly repeatedly performed in an alternating manner.

In the second preferred embodiment described above, the discharge nozzles331and332are disposed near the top portion of the inner bath211, the discharge nozzles341and342are disposed near the bottom portion of the inner bath211, and the discharge nozzles351and352are disposed above and near the discharge nozzles341and342. The positional relationship between the discharge nozzles331,332,341,342,351and352is not necessarily limited to this. For example, the discharge nozzles351and352may be disposed below the discharge nozzles341and342.

Although the discharge nozzles351and352discharge the processing liquid toward the side walls312aand312bof the inner bath211according to the second preferred embodiment described above, the discharge nozzles351and352may discharge the processing liquid toward the bottom wall311of the inner bath211. In other words, the discharge nozzles351and352are required only to discharge the processing liquid toward any inner wall surface of the inner bath211. It is desirable that the inner wall surface of the inner bath211which receives the processing liquid discharged from the discharge nozzles351and352is formed with the grooves216as in the second preferred embodiment. Without the formation of the grooves216, it is however possible to diffuse the processing liquid discharged from the discharge nozzles351and352, thereby forming low-speed liquid flows within the inner bath211.

The diameter of the discharge openings331a,332a,341a,341b,342a,342b,351a,351b,352aand352bformed in the discharge nozzles331,332,341,342,351and352is not particularly mentioned according to the second preferred embodiment described above. The discharge openings331a,332a,341a,341b,342aand342bmay have a diameter of the order of, for example, 0.70 mm to 1.0 mm (e.g., 0.85 mm), and the discharge openings351a,351b,352aand352bmay have a diameter of the order of, for example, 0.80 mm to 1.50 mm (e.g., 1.10 mm). The discharge openings331a,332a,341a,341b,342a,342b,351a,351b,352aand352bmay have the same diameter. However, when the diameter of the discharge openings351a,351b,352aand352bis slightly greater than that of the discharge openings331a,332a,341a,341b,342aand342b,a difference in speed between the liquid flows formed in the inner bath211may be made greater.

The grooves216according to the second preferred embodiment described above are grooves of a V-shaped cross-sectional configuration defined by the pair of tapered surfaces216aand216b. The configuration of the grooves216, however, may be other configurations such as a curved surface (semicylindrical) and the like.

Although the second preferred embodiment described above employs the dilute hydrofluoric acid, the SC-1 solution, the SC-2 solution and the deionized water as the processing liquid, the substrate processing apparatus according to the present invention may use other processing liquids to process the substrates W. The present invention is applicable not only to a substrate processing apparatus which processes semiconductor substrates but also to substrate processing apparatuses which process various substrates such as glass substrates for a liquid crystal display device, glass substrates for a photomask and the like.