JP2007036152A - Wafer cleaning/drying method and wafer cleaning/drying equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide easy-to-use wafer cleaning/drying equipment which ensures that there are no residual watermark or particle, and to provide a wafer cleaning/drying method. <P>SOLUTION: The wafer cleaning/drying equipment is provided with a cleaning tub 2 filled with a cleaning liquid 8 and a nozzle 3 for supplying an IPA gas 9. A wafer W which is horizontally immersed in the cleaning liquid 8 in the cleaning tub 2 after cleaning is moved closer to the nozzle 3 for injecting the IPA gas 9, and then the cleaning liquid 8 present on the wafer W is removed around the peripheral portion of the wafer W by the injection of the IPA gas 9 for a drying process. Such a method can clean and dry the wafer W without the residue of water or particles on the wafer W. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer cleaning / drying method and a wafer cleaning / drying apparatus for cleaning and drying a wafer such as a semiconductor device or an electronic component.

  Wafers such as semiconductor devices and electronic components are subjected to various processes such as cutting and polishing in the course of manufacturing. For example, polishing of a wafer by CMP is performed by holding a wafer with a wafer holding head, pressing the wafer against a rotating polishing platen with a predetermined pressure, and a chemical polishing agent (hereinafter, “ (Referred to as "slurry").

  The wafer polished by such a wafer polishing apparatus is cleaned by a cleaning apparatus, and the slurry adhering to the wafer is removed. The cleaned wafer is dried by a drying device provided in the cleaning device or adjacent to the cleaning device.

  In the drying process, conventionally, spin drying or the like in which a wafer is rotated to remove surface moisture by centrifugal force has been performed. However, in spin drying, water is separated into a plurality of water droplets and remains without being removed from the wafer, resulting in a watermark, or particle residue due to rebounding of the splashed water droplets. there were.

  Therefore, at present, a wafer is placed in a cleaning liquid such as pure water or deionized water, the cleaning liquid is discharged, and a gas of isopropyl alcohol (Iso-Propyl Alcohol, hereinafter referred to as IPA) is sent into a sealed cleaning tank. A Marangoni-type drying apparatus (see, for example, Patent Document 1) that performs drying while preventing the residual of particles by utilizing the difference in surface tension between the gas and the IPA gas.

Or a nozzle that supplies cleaning liquid to the rotating wafer while moving from the center to the outer periphery of the wafer, and a nozzle that supplies IPA gas for drying provided in the vicinity of the cleaning nozzle that moves together with the cleaning nozzle Thus, there has been proposed a cleaning / drying apparatus that generates a Marangoni force to clean and dry a wafer (see, for example, Patent Document 2).
JP 2003-224104 A JP 2004-140196 A

  However, in the drying apparatus as described in Patent Document 1, it is necessary to keep the wafer upright in order to prevent the cleaning liquid from remaining on the wafer surface. The transport system of the apparatus is very complicated and large in size, and is not suitable for an apparatus that processes one sheet at a time. Further, when the transportation system becomes complicated and takes a long time to move, when a slurry that easily aggregates is used, the slurry after polishing is aggregated during transportation, which makes cleaning difficult.

  Further, in the cleaning / drying apparatus described in Patent Document 2, when the wafer is not kept horizontal, the cleaning liquid flows to one side, making it difficult to obtain an effective Marangoni force. Further, since the wafer is rotated, the cleaning liquid on the wafer flows toward the outer peripheral portion of the wafer, and the supplied IPA gas also flows from the central portion toward the outer peripheral portion. It was difficult to balance the force, and as a result, there was a problem of leaving a water mark on the wafer surface.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a simple wafer cleaning / drying method and wafer cleaning / drying apparatus which are free from watermarks and particle residues.

  In order to achieve the above object, the present invention has a surface tension higher than that of a wafer immersed horizontally in a first fluid for cleaning in a cleaning tank and the first fluid for drying the wafer after cleaning. A nozzle for supplying a small second fluid is relatively approached, and the first fluid on the wafer is moved from the inside to the outer periphery of the wafer by the second fluid to dry the wafer. It is characterized by that.

  According to the present invention, the cleaning tank is provided with a drain port for discharging the first liquid, and a moving mechanism for moving the wafer is provided in the cleaning tank. It is also characterized in that a plate is provided at the tip of the nozzle in parallel with the wafer placed in the cleaning tank.

  Further, in the present invention, the first fluid for cleaning the wafer is sprayed toward the surface of the wafer, so that the wafer is cleaned while keeping the wafer equivalent to the state immersed in the first fluid. A cleaning liquid injection port provided around the substrate, a cleaning tank in which the wafer is cleaned, and a jet supplied with a second fluid having a lower tension than the first fluid for drying the wafer after cleaning. It is also characterized by comprising a nozzle provided with at least one mouth.

  According to the present invention, the wafer after cleaning is immersed in the first fluid for cleaning horizontally, or is equivalent to the state in which the wafer is horizontally immersed in the fluid by the first fluid ejected from the cleaning liquid ejection port. The A second fluid for drying is supplied from the nozzle toward the vicinity of the center of the upper surface of the wafer immersed in the first fluid. When the nozzle approaches the wafer in this state, the pressure of the second fluid that strikes the wafer gradually increases, and as shown in FIG. 11, the force that the first fluid pushes toward the center of the wafer and the second fluid Creates a state in which the force of pushing the first fluid to the outer periphery of the wafer is balanced with good controllability.

  At this time, the Marangoni force generated near the interface between the two liquids works effectively due to the difference in surface tension between the first fluid and the second fluid, and the first fluid on the upper surface of the wafer slowly moves toward the outer periphery of the wafer. And move.

  After the first fluid has moved to the outer periphery of the wafer, the first fluid is discharged from the drain port provided in the cleaning tank, or the wafer is lifted from the first fluid by the wafer moving mechanism and the wafer is taken out.

  As a result, moisture on the wafer is completely removed without leaving particles on the wafer surface. Further, since the wafer can be dried while being placed in a horizontal state, a rotating mechanism, a complicated transfer device, a large tank, and the like are unnecessary, and the device is downsized and can be handled easily.

  As described above, according to the wafer cleaning / drying method and the wafer cleaning / drying apparatus of the present invention, the wafer can be cleaned and dried without any moisture or particles remaining on the wafer by a small and simple apparatus. Is possible.

  Preferred embodiments of a wafer cleaning / drying method and a wafer cleaning / drying apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  First, the configuration of a wafer cleaning / drying apparatus according to the present invention and a wafer polishing apparatus incorporating the wafer cleaning / drying apparatus will be described. FIG. 1 is a plan sectional view of a wafer polishing apparatus.

  As shown in FIG. 1, the wafer polishing apparatus 10 includes a cleaning / drying apparatus 1, a wafer storage unit 20, a conveying unit 14, polishing units 16, 16, 16, and a film thickness measuring unit 29.

  The wafer storage unit 20 includes a product wafer storage unit 20A, a dummy wafer storage unit 20B, a first monitor wafer storage unit 20C, and a second monitor wafer storage unit 20D. Each storage unit stores a wafer stored in a cassette 24. W is stored. Two product wafer storage portions 20A are provided side by side. The first monitor wafer storage section 20C uses the lower stage of the cassette 24, and the upper stage of the same cassette 24 is the second monitor wafer storage section 20D.

  The transport means 14 includes an index robot 22, a transfer robot 30, and transport units 36A and 36B.

  The index robot 22 is provided with two arms that can turn and bend freely, and is provided so as to be movable along the arrow Y direction in FIG. The index robot 22 takes out a wafer W to be polished from a cassette 24 placed in each wafer storage unit, transports it to the film thickness measuring means 29 and the delivery ports 26 and 28, and also cleans the wafer W after cleaning. It is received from the cleaning / drying apparatus 1 and stored in the cassette 24.

  The transfer robot 30 includes a load arm 30A and an unload arm 30B that can be bent and swiveled, and is provided so as to be movable along the direction of the arrow X shown in FIG.

  The loading arm 30A is used for transporting the wafer W before polishing, receives the unpolished wafer W from the delivery ports 26 and 28 with a pad (not shown) provided at the tip, and transports the wafer W to the transport units 36A and 36B. .

  The unloading arm 30B is used for transporting the polished wafer W, receives the polished wafer W from the transport units 36A and 36B with a pad (not shown) provided at the tip, and receives the cleaning / drying apparatus 1 or the unload cassette. To 32.

  The transport units 36A and 36B are both movably provided along the arrow Y direction shown in FIG. 1, and move between the receiving positions SA 1 and SB and the delivery positions TA 1 and TB, respectively. The wafer W to be polished is received from the loading arm 30A of the transfer robot 30 at the receiving positions SA and SB, moved to the transfer positions TA and TB, and transferred to the polishing heads 38A and 38B. Further, the polished wafer W is received at the delivery positions TA 1 and TB 2, moved to the reception positions SA 2 and SB 1, and delivered to the unloading arm 30 B of the transfer robot 30.

  Each of the transfer units 36A and 36B has two separate cradles, and these two cradles are used separately for the wafer W before polishing and for the wafer W after polishing.

  The polishing means 16, 16, and 16 polish the wafer W, and as shown in FIG. 1, polishing surface plates 34A, 34B, and 34C, polishing heads 38A and 38B, slurry supply nozzles 37A, 37B, and 37C, and a carrier cleaning unit. 40A and 40B are provided.

  The polishing surface plates 34A, 34B, 34C are formed in a disk shape, and three of them are arranged in parallel. A polishing pad (not shown) is affixed to the upper surface of each polishing surface plate 34A, 34B, 34C, and slurry is supplied from the slurry supply nozzles 37A, 37B, 37C onto the polishing pad. Further, each polishing platen 34A, 34B, 34C is driven and rotated by a motor (not shown), and the wafer W is pressed against the rotating polishing platen 34A, 34B, 34C, whereby the wafer W is polished.

  Here, of the three polishing surface plates 34A, 34B, 34C, the left and right polishing surface plates 34A, 34B are used for polishing the first polishing target film, and the central polishing surface plate 34C is the second polishing target film 34C. Used for polishing. In both types of polishing, the type of slurry to be supplied, the rotation speed of the polishing head and the rotation speed of the polishing surface plate, the pressing force of the polishing head, the material of the polishing pad, and the like are changed.

  Dressing devices 35A, 35B, and 35C are provided in the vicinity of the polishing surface plates 34A, 34B, and 34C, respectively. The dressing devices 35A, 35B, and 35C have a pivotable arm, and dress the polishing pads on the polishing surface plates 34A, 34B, and 34C with a dresser provided at the tip of the arm. Two polishing heads, 38A and 38B, are provided, each being movably provided along the direction of arrow X in FIG.

  The polishing head 38A presses the held wafer W against the polishing pad on the polishing surface plate 34A, and supplies the slurry onto the polishing pad while rotating the polishing surface plate 34A and the polishing head 38A, respectively. Is polished. The polishing head 38B on the other side is similarly configured.

  As shown in FIG. 1, two carrier cleaning units 40A and 40B are installed between the polishing surface plates 34A, 34B and 34C, and are arranged at predetermined delivery positions TA and TB of the transport units 36A and 36B, respectively. Has been. The carrier cleaning units 40A and 40B clean the carriers of the polishing heads 38A and 38B after completion of polishing.

  The film thickness measuring means 29 has a centering mechanism for the wafer W and a film thickness measuring machine. In the film thickness measuring device, when the film to be polished is an oxide film, an optical interference type film thickness measuring machine or the like is used. Used.

  The cleaning / drying apparatus 1 cleans and dries the wafer W after polishing. The cleaning / drying apparatus 1 includes a plurality of cleaning tanks 2 and a plurality of nozzles 3.

  In the cleaning tank 2, there are a supply port 5 for supplying a cleaning liquid as a first fluid using an alkaline solution, acidic chemical liquid, deionized water, or pure water, and a drain port 4 for discharging the cleaned cleaning liquid. Is provided. Further, in the cleaning tank 2, as shown in FIG. 2, a plurality of support portions (moving mechanisms) 6 for placing the wafer W and moving it up and down are provided.

  The nozzle 3 includes a nozzle body 12 that can rotate in the direction of arrow A shown in FIG. 2 and can move up and down in the direction of arrow B, and a plate 11 that is provided horizontally with the wafer W at the tip of the nozzle body 12. Is done.

  In the nozzle body 12, an injection port for injecting IPA gas as the second fluid or vapor containing IPA gas is formed. The plate 11 is provided so that when the nozzle body 12 and the wafer W approach each other, the IPA gas sprayed from the tip of the nozzle body 12 strikes the wafer W and does not blow up to the nozzle 3 side but flows in the lateral direction. .

  The nozzle 3 rotates in the direction of arrow A and retracts from the wafer W when the wafer W is placed on the support unit 6 or moved from the instruction unit 6 by the index robot 22 or the transfer robot 30.

  When drying the wafer W after cleaning, the nozzle 3 rotates and moves onto the wafer W immersed in the cleaning liquid, and the IPA gas is injected from the nozzle body 12 to the vicinity of the center of the wafer W after the rotation. In this state, the nozzle body 12 is lowered, the wafer W is raised by the support portion 6, or the nozzle body is lowered and the wafer W is raised by the support portion 6 so that the wafer W and the nozzle 3 are relatively close to each other and dried. To do.

  With the configuration as described above, the wafer cleaning and drying apparatus according to the present invention can perform cleaning and drying of a wafer without leaving moisture or particles on the wafer with a simple and compact apparatus configuration. .

  In the present embodiment, the cleaning liquid is supplied from the supply port 5 provided in the cleaning tank 2 to immerse the wafer in the cleaning liquid. However, the present invention is not limited to this, and as shown in FIG. It is also possible to suitably carry out by injecting the cleaning liquid onto the wafer W from the cleaning liquid injection port 51 provided in the cleaning tank 2 of the apparatus 50 and maintaining the same state as when the wafer W is immersed in the cleaning liquid. .

  Next, a cleaning / drying method of the wafer cleaning / drying apparatus according to the present invention will be described. 3, 4, and 5 are cross-sectional side views schematically showing the cleaning / drying apparatus 1.

  As shown in FIG. 3, the cleaning liquid 8 is supplied into the cleaning tank 2 from the supply port 5, and the wafer W placed on the plurality of support portions (moving mechanisms) 6 is immersed in the cleaning liquid 8. The wafer W immersed in the cleaning liquid 8 is cleaned with a double side brush (not shown) or a pen brush using ultrasonic water (not shown).

  After cleaning the wafer W, the nozzle 3 moves onto the wafer W, and the IPA gas 9 as the second fluid is sprayed from the ejection port 7 toward the vicinity of the center of the wafer W. At this time, the upper surface of the wafer W is located at a depth h shown in FIG. 3 from the liquid surface of the cleaning liquid 8. The depth h is 5 mm or less.

  The nozzle body 12 that injects the IPA gas 9 toward the vicinity of the center of the upper surface of the wafer W descends and approaches the wafer W as shown in FIG. Along with this, the IPA gas 9 passes between the wafer W and the plate 11, the pressure of the IPA gas hitting the upper surface of the wafer W increases, and the cleaning liquid 8 moves toward the outer peripheral portion of the wafer W.

  At this time, at the boundary surface between the cleaning liquid 8 and the IPA gas 9, due to the difference in surface tension between the cleaning liquid 8 and the IPA gas 9, a portion containing the IPA gas 9 in the cleaning liquid 8 and a portion not so are mixed. . As a result, due to the Marangoni effect, the particles and the cleaning liquid 8 on the wafer W are moved to the outer peripheral portion without leaving them, and the particles and the cleaning liquid 8 on the wafer are completely removed.

  As the nozzle 3 further approaches the wafer W as shown in FIG. 5, the pressure with which the IPA gas 9 hits the upper surface of the wafer W further increases, and the cleaning liquid 8 is completely moved to the outer peripheral portion of the wafer W to dry the upper surface side of the wafer. Is completed.

  In this state, the cleaning liquid 8 is discharged from the drain port 4, or the nozzle 3 is raised and the wafer W is raised by the support portion 6, whereby the wafer W is taken out from the cleaning liquid 8 and the wafer drying operation is completed.

  In the present embodiment, the nozzle 3 is lowered and approaches the wafer W. However, the present invention is not limited to this, and the nozzle 3 is fixed and the wafer W is raised by the support portion 6. It is also possible to suitably use a mode in which the wafer W is brought close to the wafer W by drying the wafer W by raising the nozzle and lowering the nozzle 3.

  Next, another embodiment of the wafer cleaning / drying method and wafer cleaning / drying apparatus according to the present invention will be described. 6, 7, and 8 are cross-sectional side views schematically showing a cleaning / drying apparatus 1 according to another embodiment.

  The nozzle 17 shown in FIG. 6 is provided so as to be able to contact and separate from the wafer W similarly to the nozzle 3, and moves onto the wafer W when the wafer W is dried. The nozzle 17 that has moved onto the wafer W is kept parallel to the wafer W soaked in the cleaning liquid 8, and approaches and stops at a predetermined height.

  The nozzle 17 is provided with a plurality of injection ports 18A, 18B, 18C, and 18D for injecting the IPA gas 9 toward the outer peripheral portion of the wafer W, and the injection ports can inject IPA gas separately. .

  In this state, the nozzle 17 first injects the IPA gas 9 onto the wafer W from the injection port 18A located near the center of the wafer W, as shown in FIG. The cleaning liquid 8 on the wafer W moves toward the outer periphery of the wafer W by the injected IPA gas 9.

  At this time, at the boundary surface between the cleaning liquid 8 and the IPA gas 9, due to the difference in surface tension between the cleaning liquid 8 and the IPA gas 9, a portion containing the IPA gas 9 in the cleaning liquid 8 and a portion not so are mixed. . As a result, due to the Marangoni effect, the particles and the cleaning liquid 8 on the wafer W are moved to the outer peripheral portion without leaving them, and the particles and the cleaning liquid 8 on the wafer are completely removed.

  When the cleaning liquid 8 on the wafer W moves to a predetermined position, the nozzle 17 further injects the IPA gas 9 from the injection port 18B to expand the injection area of the IPA gas 9 as shown in FIG. 8 is moved to the outer periphery of the wafer W.

  Thereafter, the area to be further sprayed is expanded to the spray ports 18C and 18D, and finally the cleaning liquid 8 is completely moved to the outer peripheral portion of the wafer W, whereby the drying of the wafer upper surface side is completed.

  In this state, the cleaning liquid 8 is discharged from the drain port 4, or the nozzle 17 is raised and the wafer W is raised by the support portion 6, whereby the wafer W is taken out from the cleaning liquid 8 and the wafer drying operation is completed.

  In this embodiment, there are four injection ports, the injection ports 18A, 18B, 18C, and 18D. However, the present invention is not limited to this, and the number and position of the injection ports are appropriately selected depending on the size of the wafer W and the like. Is done.

  As described above, according to the wafer cleaning / drying method and the wafer cleaning / drying apparatus according to the present invention, the difference in surface tension between the first fluid and the second fluid is utilized while the wafer is placed in a horizontal state. It is possible to use the Marangoni effect, which prevents particles from remaining on the wafer surface and the generation of watermarks.

  In addition, since a rotating mechanism, a complicated transfer device, a large tank, and the like are unnecessary, the device is downsized, and as shown in FIG. In addition, it is possible to realize a simple wafer handling with a high throughput.

  In this embodiment, the wafer cleaning / drying method and the wafer cleaning / drying apparatus according to the present invention are described as being incorporated into a wafer polishing apparatus. However, the present invention is not limited to this, and the wafer cleaning / drying apparatus alone or other Can be incorporated into and used in other devices.

1 is a plan sectional view of a polishing apparatus incorporating a wafer cleaning / drying apparatus according to the present invention. The front perspective view of a wafer cleaning / drying apparatus. The cross-sectional side view which represented the washing | cleaning drying apparatus typically (before drying operation). The cross-sectional side view which represents the washing | cleaning drying apparatus typically (drying). A sectional side view schematically showing a washing and drying apparatus (at the end of drying). The cross-sectional side view which represented the washing | cleaning drying apparatus of another embodiment typically (at the time of drying start). Sectional side view (during drying) which represented the washing | cleaning drying apparatus of another embodiment typically. Sectional side view which represented the washing | cleaning drying apparatus of another embodiment typically (at the time of completion | finish of drying). The front perspective view of the washing-drying apparatus provided with the washing | cleaning-liquid injection port. The cross-sectional side view which represented typically the washing-drying apparatus of the piled-up state. The schematic diagram which showed the principle of the washing-drying apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,50 ... Cleaning-drying apparatus, 2 ... Cleaning tank, 3, 17 ... Nozzle, 4 ... Drain port, 5 ... Supply port, 6 ... Support part (movement mechanism), 7, 18A, 18B, 18C, 18D ... Injection port , 8 ... Cleaning liquid (first fluid), 9 ... IPA gas (second fluid), 10 ... Wafer polisher, 20A ... Product wafer storage, 20B ... Dummy wafer storage, 20C ... First monitor wafer storage , 20D ... second monitor wafer storage unit, 21 ... second control means, 22 ... index robot, 26, 28 ... delivery port, 29 ... thickness measuring means, 30 ... transfer robot, 32 ... unload cassette, 34A 34B, 34C ... Polishing surface plate, 36A, 36B ... Conveying unit, 38A, 38B ... Polishing head, 51 ... Cleaning liquid injection port, W ... Wafer

Claims (8)

  A wafer horizontally immersed in a first fluid for cleaning in a cleaning tank, and a nozzle for supplying a second fluid having a surface tension smaller than that of the first fluid for drying the wafer after cleaning. A wafer cleaning / drying method, wherein the wafer is dried by moving the first fluid on the wafer from the inside to the outer periphery of the wafer by the second fluid.   A wafer immersed horizontally in a first fluid for cleaning in a cleaning tank is expanded from a nozzle having a plurality of injection ports to an outer peripheral portion from the inside of the wafer, A second fluid having a surface tension smaller than that of the first fluid for drying the wafer is supplied, and the first fluid on the wafer is moved to the outer peripheral portion of the wafer by the second fluid. A wafer cleaning and drying method comprising drying the wafer. A cleaning tank filled with a first fluid for cleaning the wafer;
A wafer cleaning / drying apparatus comprising: a nozzle provided with at least one ejection port to which a second fluid having a tension lower than that of the first fluid for drying the wafer after cleaning is supplied. . By spraying a first fluid for cleaning the wafer toward the wafer surface, the wafer is provided around the wafer for cleaning while keeping the wafer equivalent to the state immersed in the first fluid. A cleaning liquid injection port;
A cleaning tank in which the wafer is cleaned;
A wafer cleaning / drying apparatus comprising: a nozzle provided with at least one ejection port to which a second fluid having a tension lower than that of the first fluid for drying the wafer after cleaning is supplied. .   The wafer cleaning / drying apparatus according to claim 3, wherein the cleaning tank is provided with a drain port for discharging the first liquid.   6. The moving mechanism according to claim 3, further comprising: a moving mechanism for placing the wafer in the cleaning tank and moving the wafer in a vertical direction. The wafer cleaning / drying apparatus described.   The wafer cleaning / drying apparatus according to claim 3, wherein the nozzle is provided so as to be able to contact and separate from the wafer.   8. The plate according to claim 3, wherein the tip of the nozzle is provided in parallel with the wafer placed in the cleaning tank. The wafer cleaning / drying apparatus according to 1.

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