JP4517768B2 - Foreign matter removal device - Google Patents

Description

      The present invention relates to a technique for removing foreign substances adhering to a substrate formed of silicon or a compound used in a semiconductor element manufacturing process or a substrate formed of glass or resin used in a flat panel display.

      When manufacturing a semiconductor element on a substrate such as silicon, glass, or resin, there is a problem that the yield is lowered due to the presence of foreign matter such as dust or particles in the manufacturing apparatus or between moving apparatuses. . In recent years, not only the surface on which semiconductor elements are formed, but also the back surface, that is, the management of foreign matter on the surface that comes into contact with members constituting them at the time of loading into a manufacturing apparatus or handling in a transfer mechanism is required. This is because foreign matter can not be fitted tightly when it is sandwiched between the back surface of the wafer and the stage that holds the wafer and floats, which may cause focus shift in the exposure apparatus. The insulating layer of the electrode of the electric chuck may be damaged, and the electrode part of the electrostatic chuck may become unrepairable due to electric discharge. Further, in the CVD apparatus, foreign matter may be mixed in the formed layer during the thin film formation. Further, when the foreign matter is metallic, the foreign matter detached from the wafer in the cleaning layer may adhere to the wafer to be processed next, and diffusion of foreign matter becomes a problem. In particular, when the semiconductor junction region or the like is contaminated with a metal foreign substance, the junction potential fluctuates, the element characteristics deviate from the design values, and the integrated circuit as a final product malfunctions.

International guidelines on these events are compiled by an organization called the International Semiconductor Technology Roadmap (ITRS) and are published on the Internet homepage (URL is http://public.itrs.net/). For example, in the year 2003 version front end processing, the allowable particle guideline on the wafer surface in 2006 is a 300 mm diameter wafer surface, the critical particle size is 35 nm, and the number of particles per wafer is 64. Further, it is indicated that the metal foreign matter in the gate oxide of the MOS transistor is desirably 1 × 10 ¹⁰ atm / cm ² or less. In principle, there is no particle adhesion to wafers that have just been manufactured and shipped, and transfer between devices in a semiconductor manufacturing plant is generally performed in a clean environment. Is considered to occur in semiconductor manufacturing equipment. Various processes are performed in the apparatus, but when the material is deposited on the surface of the wafer, such as photoresist and metal used in the apparatus, and when the probability of foreign matter adhesion increases in the process of etching to remove a part of the wafer. Conceivable.

      There is a technique called an RCA cleaning method that has been disclosed as a method for removing foreign substances adhering to a wafer. This is one of the processes called wet cleaning, in which particles are removed using a mixture of aqueous ammonia and hydrogen peroxide, and metal ions are removed using a mixture of hydrochloric acid and hydrogen peroxide. Used by combining two processes. Japanese Patent Application Laid-Open No. 6-232108 discloses a method of removing foreign matter adhering to the back surface of a semiconductor wafer by attaching an adhesive tape wound around a roller to the same surface and peeling it off afterwards in one of the processes called dry cleaning. . Japanese Patent Application Laid-Open No. 6-120175 discloses a method for removing foreign matter adhering to the back surface of a wafer by plasma processing. Japanese Patent Application Laid-Open No. 7-94462 discloses a method in which a special solution is applied to the wafer surface, the wafer is rotated around the central axis of the surface, and then washed away with pure water or the like. Japanese Patent No. 3533447 discloses a method in which the adhesive layer is specified by a method using an adhesive tape as described above. Japanese Patent Application Laid-Open No. 8-222538 discloses a method for removing foreign substances by blowing an inert gas along the surface of a wafer. Japanese Patent Laid-Open No. 11-102849 discloses a method of sweeping out foreign matter by rubbing the surface of a wafer with a brush. In the wet cleaning method listed here, there is a concern about the adhering of a new foreign substance in the cleaning liquid, and it takes a great deal of cost to prepare the cleaning liquid and process the waste liquid. It is not considered. In addition, when applying a dry adhesive tape, the wafer may be damaged due to the force applied to the wafer when the tape is peeled off. Considering that the end cost is in the range of several million to 10 million, it is considered to be a very risky method. Plasma treatment and inert gas blowing techniques can cause new foreign matter to adhere during the treatment. In the plasma processing, there is a possibility that the members of the processing chamber are scattered by sputtering due to the collision of ions. On the other hand, in the inert gas spraying method, it is considered that the management of the impurity concentration of the gas used is particularly problematic.

Japanese Patent Laid-Open No. 6-232108 JP-A-6-120175 Japanese Unexamined Patent Publication No. 7-94462 Japanese Patent No. 3533447 JP-A-8-222538 JP-A-11-102849

      An object of the present invention is to cope with the removal of foreign matter adhering to the back surface of a wafer formed from a semiconductor, glass, a substrate, or a resin or a large-diameter wafer or a large-area substrate. A second object of the present invention is to provide an apparatus capable of continuously removing foreign substances adhering to the back surface of a wafer or a substrate. Furthermore, the third problem of the present invention is that the processing time required for each wafer or substrate can be reduced by having a function capable of optimally adjusting the effect of removing foreign matter depending on the amount or size of the foreign matter adhering to the wafer or substrate. It is to minimize. Finally, the former three issues are to be realized at low cost.

      The outline is shown below first. By adsorbing the substrate to the adsorption surface of the electrostatic chuck for a certain period of time via the resin sheet, foreign substances adhering to the substrate are removed by capturing the resin sheet. Here, the resin sheet does not have an adhesive surface. As a result, the force applied to the substrate is equivalent to that of an electrostatic chuck used in ordinary semiconductor manufacturing equipment. Therefore, in principle, there is no force applied to the substrate when the adhesive tape is peeled off. it can. Therefore, in the case of semiconductor wafers, the diameter of 300 mm is currently mainstream, but it can easily cope with the next generation of 450 mm. Regarding the material of the resin sheet, it is necessary to consider hardness and price. This is because the foreign matter cannot be captured well unless a soft material is used as compared with the electrostatic chuck or the substrate. It is necessary to use an inexpensive resin sheet. This is because it is the simplest in terms of management to dispose the portion once the foreign matter has been captured. In order to process multiple substrates in succession, resin sheets are mounted in rolls, new resin sheets are sent out for each substrate, and foreign substances adhering to the substrates are captured. It is necessary to wind up and replace all the resin sheets with new ones. In addition, a series of these operations requires a robot arm that can load a substrate into the electrostatic chuck or recover the substrate from the electrostatic chuck.

      Next, a sheet used for capturing foreign matter will be described. Since the electrostatic chuck surface needs to be a hard surface, for example, ceramic such as alumina, silicon carbide, or aluminum nitride is used. For example, Knoop hardness of silicon carbide and alumina is 2500Hk and 2100Hk, respectively. On the other hand, the Knoop strength of the substrate such as silicon is 960 Hk. The dust and particles as foreign matter are 300 Hk when the composition is iron, which is most harmful to semiconductor manufacturing. In order to effectively capture foreign substances, a material having a hardness value lower than these must be used. A suitable Knoop hardness for this purpose is 20-200 Hk. Resins are relatively softer than the materials listed above and usually have a hardness of about 100 Hk, which is appropriate for this purpose. When the substrate is glass, a softer material is appropriate for the sheet that captures foreign matter. This is because the Knoop hardness of the glass is 315 Hk, which is as high as that of a foreign substance. Suitable hardness is in the range of 20 to 200 Hk, more preferably 20 to 100 Hk.

      Suitable materials for the resin sheet include, for example, polyvinyl alcohol, low density polyethylene, polyethylene, polyvinylidene chloride, polyvinyl chloride, polypropylene, polyethylene terephthalate, acetyl cellulose, polycarbonate, nylon, polyimide, aramid, polycarbodiimide, and the like. Among these, polyvinyl alcohol, low density polyethylene, polyethylene, polyvinylidene chloride, polyvinyl chloride, polypropylene, and polyethylene phthalate are more preferable from the viewpoint of price. It is also possible to use a rubber-based material such as silicon. The thickness of the resin sheet is preferably 5 to 30 μm. This is because if it is thicker than 30 μm, the attractive force of the electrostatic chuck becomes small. On the other hand, if the thickness is less than 5 μm, the sheet is difficult to handle and may be torn.

When the volume resistance value of the resin sheet is lowered, the substrate may be more strongly attracted to the electrostatic chuck. This is the case when the electrostatic chuck exhibits the Johnson-Rahbek force. That is, a minute current from the electrode of the electrostatic chuck is transmitted to the substrate through the periphery of the electrode and the attracting surface, and a large electrostatic attracting force is generated in the minute gap between the substrate and the attracting surface. Therefore, although the resin sheet listed above exhibits high electrical insulation (in the range of 10 ¹⁵ to 10 ¹⁸ Ω · cm in volume resistance), the volume resistance value is obtained by mixing a conductive feeler into the resin sheet. By making the range of about 10 ⁹ to 10 ¹³ Ω · cm, it is possible to increase the attractive force of the substrate to the electrostatic chuck.

      Since the resin sheet is brought into contact with the substrate and then separated, there may be a case where contact / peeling charging is involved. When the substrate or the resin sheet is charged, it is conceivable that the foreign matter captured by the resin sheet again due to static electricity separates from the resin sheet and adheres to the substrate. In this case, a device for neutralizing static electricity, such as an ionizer, is installed in the foreign matter removing device, and the neutralizing particles between the substrate and the resin sheet, and between the resin sheet and the electrostatic chuck, are positive or negative. It can be solved by spraying ions.

      The configuration of the foreign matter removing apparatus according to the present invention will be described below. This apparatus has an electrostatic chuck composed of two or more suction surfaces and a function of raising and lowering one or more suction surfaces of the electrostatic chuck. By making the electrostatic chuck into a divided configuration, a part of the electrostatic chuck can be raised and lowered to facilitate loading and recovery of the substrate. It has a part for loading a resin sheet wound in a roll shape, a mechanism for guiding the resin sheet to the adsorption surface of the electrostatic chuck, and a part for winding the used resin sheet in a roll shape. A mechanism for guiding the resin sheet from the adsorption surface to the winding portion; As a result, the substrate can be loaded, foreign matter can be captured, and after the substrate is recovered, a new resin sheet can always be disposed for processing the next substrate. Furthermore, it has one or more sets of robot arms and one or more sets of push-up pins for the substrates on the upper surface of the resin sheet laid on the adsorption surface of the electrostatic chuck. When collecting the substrate, a part of the chucking surface of the electrostatic chuck is lowered, and the substrate is pushed up from below by a push-up pin, so that the substrate can be easily grasped with a fork attached to the tip of the robot arm. When the substrate is loaded on the electrostatic chuck, the substrate picked up by the fork is once placed on a push-up pin and loaded on a resin sheet laid on the adsorption surface of the electrostatic chuck. When the substrate is loaded, in order to make the surface of the electrostatic chuck the same surface, the attracting surface of the lowered electrostatic chuck is raised.

Next, the procedure of continuous processing will be described. After loading the substrate on the resin sheet laid on the electrostatic chuck's adsorption surface, the substrate is adsorbed to the electrostatic chuck for a certain period of time with the resin sheet sandwiched, and the substrate is placed on the adsorption surface side that opposes the electrostatic chuck. The foreign matter adhering to the substrate is removed by causing the resin sheet to capture the attached foreign matter. Next, one or more suction surfaces of the electrostatic chuck are lowered to collect the substrate, the used resin sheet is wound into a roll, a new resin sheet is placed on the electrostatic chuck, and the substrate to be processed next The plurality of substrates are successively processed by loading, raising one or more attracting surfaces of the electrostatic chuck to the original position, and repeating these series of operations. The adsorption time varies depending on the size and amount of foreign matter, but is 1 to 60 seconds. When the amount of foreign matter per unit area is large, the longer the adsorption time, the better the capture of foreign matter. It is preferable to use a bipolar type electrostatic chuck, and it is desirable to use an electrostatic chuck having a high adsorption ability as much as possible. The chucking force of the electrostatic chuck can be adjusted by changing the voltage applied to the chucking electrode. If the amount of foreign matter is small, it is possible to cope with the conditions by reducing the voltage or shortening the chucking time. Thus, the operating parameters can be optimized so that the processing time per sheet is minimized. The adsorption force with respect to the substrate per unit area is desirably in the range of 10 to 300 gf / cm ² .

      Since no adhesive tape is used, there is no force applied to the substrate when it is peeled off, and removal of foreign substances adhering to the back side of the substrate made of semiconductor, glass, or resin is compatible with large substrates. Is possible. Moreover, since the removal of the foreign substances adhering to the back surface of the substrate can be continuously processed, it can be used at the production site of semiconductor elements. Furthermore, the processing time required for each substrate can be reduced by having the function of optimizing the effect of removing the foreign matter depending on the amount or size of the foreign matter adhering to the substrate, using the potential applied to the electrostatic chuck and the adsorption time as parameters. It can be minimized. Finally, using an inexpensive resin sheet for capturing foreign matter makes it possible to keep maintenance costs low.

BEST MODE FOR CARRYING OUT THE INVENTION

      Hereinafter, embodiments of the present invention will be described with reference to FIGS.

      First, the basic structure will be described with reference to FIG. The electrostatic chuck is divided into three parts. A first electrostatic chuck 10 having a relatively wide central portion, a second electrostatic chuck 11 and a third electrostatic chuck 12 positioned on the left and right sides of the first electrostatic chuck 10. The second electrostatic chuck 11 and the third electrostatic chuck 12 are vertically movable. Further, the attracting surface composed of these three electrostatic chucks is a quadrangle. Each electrostatic chuck is a bipolar type, and the first electrostatic chuck 10 has two electrodes, a first electrode 13 and a second electrode 14. A power source 15 is connected to the first electrode 13 and the second electrode 14 in series with a switch 16 for turning on or off the voltage of the power source. The electrodes of the second electrostatic chuck 11 and the third electrostatic chuck 12 are connected to the first electrode 13 and the second electrode 14 of the first electrostatic chuck from a power source 15 and a switch 16 in the same manner. Resin sheet 3 is laid on top of first electrostatic chuck 10, second electrostatic chuck 11, and third electrostatic chuck 12. The resin sheet 3 has a thickness of 10 μm and is made of polyvinyl alcohol. On the top of the resin sheet 3, a substrate 1 to which foreign matter 2 is attached is disposed. In order to guide the used resin sheet 3 a to the take-up roll 6, a first guide roller 4 and a second guide roller 5 are provided on the side of the second electrostatic chuck 11. Here, the first guide roller 4 is vertically movable. A third guide roller 7 and a fourth guide roller 8 are provided on the side of the third electrostatic chuck 12 in order to supply a new resin sheet 3b from the feed roll 9 onto the three electrostatic chucks described above. Here, like the first guide roller 4, the third guard roller 7 can move up and down.

      Next, while explaining the entire procedure of the foreign matter removing method, the other components will be described. FIG. 1 shows a state in which a substrate 1 is installed on a resin sheet 2. At this time, the switch 16 of the power supply 15 of the electrostatic chuck is in an OFF state, and no suction is performed. FIG. 2 shows that the switch 16 of the power supply 15 is turned on so that the second electrostatic chuck 11 and the third electrostatic chuck 12 are equivalent to each other between the first electrode 13 and the second electrode 14 of the first electrostatic chuck 10. A state in which the substrate 1 is adsorbed by applying a voltage between the electrodes is shown. Here, it is also shown that the foreign material 2 is embedded in the resin sheet 3. The set time of the suction time and the voltage of the power source 15 can be varied. The variable range of the adsorption time is 1 to 60 seconds, and the voltage between the terminals of the power supply 15 is 0 to 8 kV. In the case of a bipolar electrostatic chuck, positive and negative potentials may be applied between the electrodes. In this case, the potential difference equivalent to the above is 0 to ± 4 kV. FIG. 3 shows the second electrostatic chuck 11 and the third electrostatic chuck 12 being lowered together with the first guide roller 4 and the third guide roller 7. Subsequent to these operations, the substrate push-up pins 17a and 17b are shown below the left and right sides of the substrate 1. The figure also shows that the foreign matter 2 is captured by the resin sheet 2. FIG. 4 shows that the used resin sheet 3 a is collected on the take-up roll 6 and a new resin sheet 3 b is supplied from the feed roll 9. In addition, the substrate 1 is recovered by the substrate push-up pins 17a and 17b so that the processed substrate 1 is lifted, and the fork 18 is positioned below the substrate 1. When the substrate 1 is loaded on the first electrostatic chuck 10, the above series of operations are performed in reverse. That is, the substrate 1 is carried to the upper part of the first electrostatic chuck by the fork 18, the substrate 2 is supported from the lower side by the substrate push-up pins 17 a and 17 b, and the fork 18 is moved away from the upper part of the first electrostatic chuck 10. The push-up pins 17a and 17b are lowered to place the substrate 1 on the suction surface of the first electrostatic chuck 10 on which the resin sheet 3 is laid. When the resin sheet 3 is completely used, a new one is loaded on the feed roll 9, and the used resin sheet 3a collected in a roll is discarded.

      FIG. 5 shows the interior of the foreign matter removing apparatus 100 as viewed from above. On the left side, there are a supply side cassette 19 for installing a plurality of substrates 1 and a collection side cassette 20 for stocking a plurality of processed substrates 1. There are two sets of robot mechanisms, and one set of robot arms 21 is shown. A fork 18 is provided at the tip of the robot arm 21 and shows the place where the substrate 1 is placed. On the right side in FIG. 5, there is a foreign matter removing mechanism 22, where the first electrostatic chuck 10 and the following guide rollers are installed. FIG. 6 is an external view of the foreign matter removing apparatus.

      The foreign matter removing apparatus of the present invention is a semiconductor wafer manufacturing factory, a semiconductor element manufacturing factory, a glass substrate manufacturing factory, a thin display apparatus manufacturing factory used for a television using liquid crystal or plasma, and a thin display apparatus using an organic material. In a manufacturing factory or the like, it is possible to provide at low cost to remove foreign substances adhering to the back surface of the substrate involved in the manufacturing.

It is a block diagram of one Example of the foreign material removal apparatus of this invention, and the state which installed the board | substrate on the resin sheet is shown. In the block diagram of one Example of the foreign material removal apparatus of this invention, the power supply 15 of an electrostatic chuck is turned ON and the substrate 1 is attracted | sucked. In the configuration diagram of one embodiment of the foreign matter removing apparatus of the present invention, the power supply 16 is turned off, the left and right second electrostatic chucks 11 and the third electrostatic chuck 12 are lowered, and at the same time the substrate push-up pins 17a and 17a are attached to the substrate. It shows the appearance of being positioned below. In the configuration diagram of one embodiment of the foreign matter removing apparatus of the present invention, the resin sheet 3a that captures the foreign matter is collected on a take-up roll, and a new resin sheet 3b is taken as the first electrostatic chuck 10, the second electrostatic chuck 11, and the third. A state in which the substrate 1 is recovered by the fork 18 is shown on the upper surface of the electrostatic chuck 12. The figure which shows the inside of a foreign material removal apparatus. The external view of a foreign material removal apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Foreign material 3 Resin sheet 3a Used resin sheet 3b New resin sheet 4 First guide roller 5 Second guide roller 6 Take-up roll 7 Third guide roller 8 Fourth guide roller 9 Feeding roll 10 First electrostatic chuck 11 Second Electrostatic Chuck 12 Third Electrostatic Chuck 13 First Electrode 14 Second Electrode 15 Power Supply 16 Switch 17 Substrate Push-up Pin 18 Fork 19 Supply Side Cassette 20 Collection Side Cassette 21 Robot Arm 22 Foreign Material Removal Mechanism 100 Foreign Material Removal Device

Claims (6)

A device that removes foreign matter adhering to the back surface of a substrate in a dry manner. A non-adhesive resin sheet having a Knoop hardness of 20 to 200 Hk is loaded between the back surface of the substrate and the electrostatic chuck, and the loaded substrate is foreign matter across the resin sheet by a predetermined time adsorbed to the electrostatic chuck, are attached foreign matters attached to the attaching object face side countercurrent against the electrostatic chuck of the substrate to the substrate by trapping in the resin sheet An apparatus for removing foreign matter from a substrate, characterized in that the substrate is removed. The foreign matter removing device has an electrostatic chuck composed of two or more attracting surfaces, a function of raising and lowering the attracting surfaces, a portion for loading a resin sheet wound in a roll shape, and the resin sheet A mechanism for guiding the chucking surface of the electrostatic chuck, a portion for winding the resin sheet in a roll shape, a mechanism for guiding the resin sheet from the chucking surface of the electrostatic chuck to the winding portion, and 2. The apparatus according to claim 1, further comprising one or more sets of robot arms and one or more sets of push-up pins for loading and collecting the substrate on the upper surface of the resin sheet laid on the suction surface. Device for removing foreign substances from substrates. The resin sheet is wound in a roll shape, a new sheet portion is sent out for each substrate, and is arranged on the adsorption surface of the electrostatic chuck, and a used sheet portion that captures foreign matters is wound up and collected in a roll shape. The foreign matter removing apparatus for a substrate according to claim 1 or 2 . The resin sheet is made of one or more materials selected from polyvinyl alcohol, low density polyethylene, polyethylene, polyvinylidene chloride, polyvinyl chloride, polypropylene, polyethylene terephthalate, acetyl cellulose, polycarbonate, nylon, polyimide, aramid, and polycarbodiimide. , the foreign matter removing apparatus according to any one of claims 1 to 3, wherein the thickness of 5~30μ m. Substrate was loaded on the resin sheet Knoop hardness 20~200Hk with a non-stick that is laid on the attracting surface of the electrostatic chuck, the substrate wherein the resin sheet by a predetermined time adsorbed on the electrostatic chuck Nde Hasa, said remove foreign matter adhering to the substrate by trapping the foreign matter attached to the attaching object face side against toward the substrate chuck of the resin sheet, lowering the one or more suction surface of the electrostatic chuck The substrate is recovered, the used resin sheet is wound up in a roll, a new resin sheet is placed on the electrostatic chuck, and then a substrate to be processed is loaded, and one or more of the electrostatic chucks are loaded. A substrate foreign matter removing method capable of processing a plurality of substrates continuously by raising the suction surface to its original position and repeating these series of operations. The resin sheet is made of one or more materials selected from polyvinyl alcohol, low density polyethylene, polyethylene, polyvinylidene chloride, polyvinyl chloride, polypropylene, polyethylene terephthalate, acetyl cellulose, polycarbonate, nylon, polyimide, aramid, and polycarbodiimide. , the foreign matter removing method according to claim 5 having a thickness, characterized in that a 5 to 30 [mu] m.

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