JP2013065685A - Chemical application device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical application device capable of preventing a wafer from being broken in an EUV exposure device.SOLUTION: A chemical application device 101 comprises: a chemical application unit 102 which applies a chemical on a principal face of a substrate; an inspection unit 104 which inspects an adhesion state of foreign matters to the entire rear surface of the substrate; and a control unit 114 which determines whether or not to carry the substrate outside as a non-defective product on the basis of an inspection result of the inspection unit 104.

Description

  Embodiments described herein relate generally to a chemical solution coating apparatus.

  In the manufacture of a semiconductor element, many steps of applying a chemical solution on a wafer and patterning it into a desired pattern are included. This patterning step is generally performed by applying a photosensitive material called a resist onto a workpiece on a wafer, and selectively developing after exposure using an exposure apparatus.

  When the wafer is exposed in the exposure apparatus, if there is a defect such as adhesion of foreign matter on the back surface of the wafer, a chucking error may occur and the wafer may be cracked.

JP 2007-281073 A

  In an EUV (Extreme UltraViolet) exposure apparatus, since the inside of the apparatus is vacuum, if a wafer crack occurs in the apparatus, it is necessary to open the atmosphere for cleaning. This has led to a significant decrease in the operating rate and a problem that productivity is reduced.

  An object of one embodiment of the present invention is to provide a chemical solution coating apparatus for preventing wafer cracking in an exposure apparatus.

  A chemical solution coating apparatus according to an embodiment of the present invention includes a chemical solution application unit that applies a chemical solution on a main surface of a substrate, an inspection unit that inspects the adhesion state of foreign matter on the entire back surface of the substrate, and the inspection unit. And a control unit for determining whether or not to carry the substrate out as a good product based on the inspection result.

FIG. 1 is a diagram showing a schematic configuration of a chemical solution coating apparatus and an EUV exposure apparatus according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of the electrostatic chuck unit according to the first embodiment. FIG. 3 is a diagram illustrating an example of the configuration of the back surface cleaning unit according to the first and second embodiments. FIG. 4 is a diagram illustrating an operation flow of the chemical solution coating apparatus according to the first embodiment. FIG. 5 is a diagram illustrating another operation flow of the chemical liquid coating apparatus according to the first embodiment. FIG. 6 is a diagram showing a schematic configuration of a chemical solution coating apparatus and an EUV exposure apparatus according to the second embodiment. FIG. 7 is a diagram illustrating a configuration of a back surface defect inspection unit according to the second embodiment. FIG. 8 is a diagram illustrating an operation flow of the chemical solution coating apparatus according to the second embodiment. FIG. 9 is a diagram illustrating another operation flow of the chemical liquid coating apparatus according to the second embodiment.

  Exemplary embodiments of a chemical liquid coating apparatus will be explained below in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a chemical solution coating apparatus 101 and an EUV exposure apparatus 112 according to the present embodiment. The chemical solution coating apparatus 101 is, for example, a resist coating apparatus used for forming a coating film in semiconductor element creation (wafer process, exposure mask manufacturing process) and liquid crystal device creation technology. The chemical solution application apparatus 101 includes a chemical solution application unit 102, a pre-bake unit 103, an electrostatic chuck unit (inspection unit) 104, a back surface cleaning unit 105, a wafer standby unit 106, a post-exposure bake unit 107, a development unit 108, and a transfer robot control unit 109. A system control unit (control unit) 114, a transfer robot 110, and a wafer loader 111. The post-exposure bake unit 107 and the development unit 108 are used after the wafer (semiconductor substrate) transferred from the chemical solution coating apparatus 101 to the EUV exposure apparatus 112 is returned to the chemical solution coating apparatus 101. I do not explain. The EUV exposure apparatus 112 includes a wafer stage 113 having an electrostatic chuck because a vacuum chuck cannot be used to evacuate the interior of the apparatus during exposure. FIG. 4 shows an operation flow of the chemical liquid coating apparatus 101 according to the present embodiment.

  First, a chemical solution dissolved in a solvent on the main surface of the wafer in the chemical solution application unit 102 is dropped from a dropping nozzle to form a coating film (step S101). The type of the chemical solution is not particularly limited, and examples thereof include a resist agent, an antireflection film agent, an oxide film agent, a ferroelectric film agent, and a spin-on-glass chemical solution. Further, the type of solvent is not particularly limited, but for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cellosolv solvents such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, lactic acid Examples thereof include ester solvents such as ethyl, ethyl acetate, butyl acetate and isoamyl acetate, alcohol solvents such as methanol, ethanol and isopropanol, other anisole, toluene, xylene and naphtha.

  Although it does not specifically limit as dripping amount of a chemical | medical solution, The range of 0.01cc-30cc, More preferably, 0.1cc-10cc can be used conveniently. The reason is that if the amount is less than 0.01 cc, it is difficult to spread the liquid film over the entire surface of the wafer because the discharge amount is too small, and if it exceeds 30 cc, the amount of chemicals that cannot be applied on the wafer increases and is not efficient. The position where the chemical solution is dropped is preferably within a radius of 1 cm from the center of the wafer, and if it is dropped on the outer periphery of the wafer, it becomes difficult to form a film with a uniform film thickness. Further, the nozzle need not always be on the wafer, and may move onto the wafer only when the chemical droplet is under. Subsequently, the wafer is rotated to form a liquid film. The rotation speed is preferably 100 to 20000, more preferably 500 to 7000 rpm. If the rotation speed is less than 100 rpm, it is difficult to spread the chemical solution uniformly on the wafer, and if it exceeds 20000 rpm, turbulent flow is generated on the outer periphery of the wafer and uniform. It is difficult to obtain a good film quality.

  The wafer on which the liquid coating film of the chemical solution is formed as described above is then transferred to the pre-bake unit 103 by the transfer robot 110 and the wafer loader 111 controlled by the transfer robot control unit 109. And the solvent in a coating film is vaporized by baking in it (step S102). The baking temperature is not limited, but a range of 50 to 600 ° C. is suitable. If the temperature is lower than 50 ° C., the solvent of the coating film is difficult to evaporate, and if it exceeds 600 ° C., the sublimation of the coating film may proceed.

  Next, the wafer is transferred to the electrostatic chuck unit 104. FIG. 2 shows a configuration of the electrostatic chuck unit 104 on which the wafer 201 is mounted. The electrostatic chuck 202 is connected to the earth 206 through the voltage module 204, and an internal charge 203 is generated in the electrostatic chuck 202 by the voltage applied by the voltage module 204. On the other hand, the wafer 201 is connected to the ground 206 via the ground wire 205.

  As shown in FIG. 2, the wafer 201 is placed on the electrostatic chuck 202, and the degree of adsorption of the back surface of the wafer 201 to the electrostatic chuck 202 is measured. The adsorption method may be either a monopolar method or a bipolar method. The applied voltage is not particularly limited, but a range of 1 mV to 10,000 V can be suitably used. If it is less than 1 mV, the adsorption is insufficient, and if it exceeds 10,000 V, the film formed on the wafer 201 This increases the possibility of electrostatic breakdown.

  Examples of the method for measuring the degree of adsorption include the following methods. The distance between the back surface of the wafer 201 and the electrostatic chuck 202 is measured using the optical interferometer 209. If the distance is equal to or greater than the threshold value, it is determined that the degree of adsorption is weak. Specifically, the laser 208 is irradiated on the back surface of the wafer 201 from the laser irradiation unit 207 and reflected, and the distance between the back surface of the wafer 201 and the electrostatic chuck 202 is measured by the optical interferometer 209. If there is a defect due to foreign matter (dust) adhesion that lowers the degree of adsorption at any position on the back surface of the wafer 201, the measured distance changes. Accordingly, this enables defect inspection of the entire back surface of the wafer 201. Then, the system control unit 114 determines whether or not the distance measured by the optical interferometer 209 is less than a predetermined threshold (step S103). If the measured distance is less than the predetermined threshold (step S103: Yes), it is determined that the degree of adsorption between the back surface of the wafer 201 and the electrostatic chuck 202 is sufficient, and the wafer 201 is transferred to the EUV exposure apparatus 112. (Step S104).

  In step S103, when the measured distance is equal to or greater than a predetermined threshold (step S103: No), the system control unit 114 determines that the degree of adsorption is insufficient, and the back surface cleaning unit 105 determines the wafer 201. The back surface is cleaned (step S105). FIG. 3 shows an example of the configuration of the back surface cleaning unit 105. The back surface cleaning unit 105 removes defects due to foreign matters attached to the back surface of the wafer 201 with the brush 304 while applying water 303 sprayed from the nozzle 302 to the back surface of the wafer 201. After the back surface cleaning, the degree of adsorption is measured again (step S103), and the measurement of the degree of washing and the degree of adsorption is repeated until the measured distance becomes less than a predetermined threshold (step S103: Yes). If it is determined that the distance measured in step S103 is equal to or greater than the threshold and the degree of adsorption is insufficient, the rear surface cleaning unit 105 does not clean the back surface of the wafer 201, for example, the chemical solution coating apparatus 101 The non-defective wafer 201 may be prevented from being conveyed to the EUV exposure apparatus 112 by a method such as accommodating the wafer 201 in a provided wafer buffer (not shown). At this time, the chemical solution coating apparatus 101 does not necessarily include the back surface cleaning unit 105. In addition, when it is determined that the degree of adsorption is insufficient, the cleaning and removal of defects due to foreign matter adhering to the back surface of the wafer 201 and the measurement of the degree of adsorption are repeated, and the measured distance is less than the threshold even after a predetermined number of repetitions. If not, the wafer 201 may be accommodated in the wafer buffer without performing the back surface cleaning again. In short, the wafer 201 in which the chucking degree with the electrostatic chuck 202 cannot be sufficiently obtained in the electrostatic chuck unit 104 is obtained. It may be prevented from being conveyed to the EUV exposure apparatus 112.

  As described above, in the present embodiment, the EUV exposure apparatus 112 determines that the wafer 201 is a non-defective product only when the electrostatic chuck unit 104 has a sufficient degree of adsorption between the back surface of the wafer 201 and the electrostatic chuck 202. The wafer 201 is transferred to the substrate. Thereby, it becomes possible to prevent the wafer from being cracked in the EUV exposure apparatus 112 due to a chucking error (adsorption error) caused by foreign matter adhering to the back surface of the wafer 201 in advance.

  In the operation flow of the chemical solution coating apparatus 101 shown in FIG. 4, the back surface cleaning (step S105) is performed after the determination of the degree of adsorption (step S103), but the back surface cleaning is performed after baking as shown in FIG. After that, the degree of adsorption may be determined. That is, it is measured by the optical interferometer 209 after chemical solution application in the chemical solution application unit 102 (step S111), baking in the pre-baking unit 103 (step S112), and back surface cleaning in the back surface cleaning unit 105 (step S113). The system control unit 114 may determine whether the measured distance is less than a predetermined threshold (step S114). When the measured distance is greater than or equal to a predetermined threshold (step S114: No), the process returns to step S113. When the measured distance is less than the predetermined threshold (step S114: Yes), the wafer 201 is moved to the EUV exposure apparatus 112. (Step S115). Further, the wafer 201 may be cleaned on the back surface by using a cleaning device outside the chemical solution coating apparatus 101.

  As another method for measuring the degree of adsorption, for example, the value of the current flowing between the wafer 201 and the electrostatic chuck 202 can be measured. That is, the greater the distance between the back surface of the wafer 201 and the electrostatic chuck 202, the greater the electrical resistance between the two, and this is used to apply a voltage between them to The current value is used as an index of adsorption. When the current value is equal to or smaller than the predetermined threshold, it is determined that the distance is long, that is, the degree of adsorption is weak, and the wafer 201 is cleaned on the back surface without being transferred to the EUV exposure apparatus 112. When the current value is larger than the predetermined threshold value, it is determined that the degree of adsorption is sufficient, and is conveyed to the EUV exposure apparatus 112. Even in this way, similarly to the above, it is possible to prevent the wafer from being cracked in the EUV exposure apparatus 112 due to a chucking error caused by foreign matter adhering to the back surface of the wafer 201 in advance. In addition, the measuring method of an adsorption degree is not limited to what was illustrated above.

(Second Embodiment)
FIG. 6 is a diagram showing a schematic configuration of the chemical solution coating apparatus 401 and the EUV exposure apparatus 112 according to the present embodiment. The chemical solution coating apparatus 401 is, for example, a resist coating apparatus used for forming a coating film in semiconductor element creation (wafer process, exposure mask manufacturing process), liquid crystal device creation technology. The chemical coating apparatus 401 includes a chemical coating unit 402, a pre-bake unit 403, a back surface defect inspection unit 404, a back surface cleaning unit 405, a wafer standby unit 406, a post exposure bake unit 407, a developing unit 408, a transport robot control unit 409, and a system control unit. (Control unit) 414, transfer robot 410, and wafer loader 411 are provided. The post-exposure bake unit 407 and the development unit 408 are used after the wafer transferred from the chemical solution coating apparatus 401 to the EUV exposure apparatus 112 is returned to the chemical solution coating apparatus 401, and will not be described below. The EUV exposure apparatus 112 includes a wafer stage 113 having an electrostatic chuck because a vacuum chuck cannot be used to evacuate the interior of the apparatus during exposure. FIG. 8 shows an operation flow of the chemical liquid coating apparatus 401 according to this embodiment.

  First, a chemical solution dissolved in a solvent on the main surface of the wafer in the chemical solution application unit 402 is dropped from the dropping nozzle to form a coating film (step S201). Conditions relating to the chemical solution application, such as the type of the chemical solution, the type of the solvent, the amount of the chemical solution dropped, and the number of rotations of the wafer when the chemical droplet is dropped, are the same as those in the first embodiment. Subsequent baking (step S202) conditions in the pre-baking unit 403 are the same as those in the first embodiment.

  After step S202, the wafer 201 is transferred to the back surface defect inspection unit 404. The back surface defect inspection unit 404 measures a defect due to adhesion of foreign matter over the entire back surface of the wafer. A method for detecting a defect due to adhesion of a foreign substance is performed by, for example, an optical means. In this case, the wavelength of light used from the infrared region to the vacuum ultraviolet region is not limited, and detection by either bright field or dark field may be used. A specific example of a method for detecting a defect due to foreign matter adhesion in the back surface defect inspection unit 404 is shown in FIG. The laser beam 503 emitted from the laser irradiation unit (scanning unit) 502 is reflected by the back surface of the wafer 201 and detected by the light receiving unit (detecting unit) 504. The laser irradiation unit 502 is moved so that the laser beam 503 scans the entire back surface of the wafer 201. At the same time, the intensity of the reflected light detected by the light receiving unit 504 is monitored, and the presence of a defect due to foreign matter adhesion is detected by a change in intensity of a predetermined value or more. Based on the detection result, the number of foreign matters (defects) attached to the entire back surface of the wafer 201 or the size of the foreign matters (defects) can be estimated. Then, the system control unit 414 determines whether the number of foreign matters attached to the entire back surface of the wafer 201 or the size of the foreign matters is equal to or less than a predetermined value (step S203). If the measured number of foreign matters or the size of the foreign matters is equal to or smaller than a predetermined value (step S203: Yes), the wafer 201 is transported to the EUV exposure apparatus 112 because there is no risk of wafer cracking in the EUV exposure apparatus 112 (step S203). S204).

  In step S203, if the number of measured foreign matters or the size of the foreign matters is larger than a predetermined value (step S203: No), the system control unit 414 determines that there is a risk of wafer cracking in the EUV exposure apparatus 112. Then, the back surface of the wafer 201 is cleaned by the back surface cleaning unit 405 (step S205). The configuration of the back surface cleaning unit 405 is the same as that shown in FIG. After the back surface cleaning, the back surface defect inspection unit 404 and the system control unit 414 determine again whether or not the number of foreign materials attached to the entire back surface of the wafer 201 or the size of the foreign materials is a predetermined value or less (step) In step S203, cleaning and back surface defect inspection are repeated until a predetermined value or less (step S203: Yes). If the number or size of the foreign matter measured in step S203 is larger than a predetermined value, for example, a wafer (not shown) provided in the chemical solution coating apparatus 401 without cleaning the back surface of the wafer 201 by the back surface cleaning unit 405. The non-defective wafer 201 may be prevented from being transferred to the EUV exposure apparatus 112 by a method such as accommodating the wafer 201 in a buffer. At this time, the chemical solution coating apparatus 401 does not necessarily include the back surface cleaning unit 405. Further, when the number or size of the foreign matter is larger than a predetermined value, the cleaning and removing of the foreign matter adhering to the back surface of the wafer 201 and the back surface defect inspection are repeated. If it is not less than the predetermined value, the wafer 201 may be accommodated in the wafer buffer without performing the back surface cleaning again. In short, the number or size of foreign matters in the back surface defect inspection unit 404 is larger than the predetermined value. It is only necessary that the measured wafer 201 is not transferred to the EUV exposure apparatus 112.

  As described above, in this embodiment, the wafer 201 is a non-defective product only when the number of foreign matters or the size of the foreign matters attached to the entire back surface of the wafer 201 measured by the back surface defect inspection unit 404 is equal to or less than a predetermined value. And the wafer 201 is transferred to the EUV exposure apparatus 112. Thereby, it becomes possible to prevent the wafer from being cracked in the EUV exposure apparatus 112 due to a chucking error (adsorption error) caused by a defect of foreign matter adhering to the back surface of the wafer 201 in advance.

  In the operation flow of the chemical coating apparatus 401 shown in FIG. 8, the back surface cleaning (step S205) is performed after the inspection of the foreign matter defect on the back surface (step S203). However, as shown in FIG. You may make it test | inspect for a foreign material defect after wash | cleaning. That is, after the chemical solution application in the chemical solution application unit 402 (step S211), the baking in the prebake unit 403 (step S212), and the back surface cleaning in the back surface cleaning unit 405 (step S213), the measurement is performed in the back surface defect inspection unit 404. The system control unit 414 may determine whether the number of foreign matters or the size of the foreign matter is equal to or less than a predetermined value (step S214). If the measured number of foreign objects or the size of the foreign objects is larger than a predetermined value (step S214: No), the process returns to step S213, and if the measured number of foreign objects or the size of the foreign objects is less than a predetermined value (step In step S214, the wafer 201 is transferred to the EUV exposure apparatus 112 (step S215). Further, the wafer 201 may be cleaned on the back surface by using a cleaning device outside the chemical solution coating apparatus 401.

  As a method for detecting a foreign substance defect, it is possible to detect by using an electron beam (electron beam) in addition to the optical means described above. In this case, the number of foreign particles or the size of the foreign matter attached to the entire back surface is determined based on the change in the intensity of secondary electrons scattered from the back surface of the wafer 201 scanned and irradiated by the electron beam. Based on the determination result, whether the transfer to the EUV exposure apparatus 112 is possible and the back surface cleaning is performed, so that the inside of the EUV exposure apparatus 112 due to a chucking error caused by a defect of foreign matter adhering to the back surface of the wafer 201 as described above. It becomes possible to prevent the wafer from cracking in advance. In addition, the detection method of a foreign material defect is not limited to what was illustrated above.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  101, 401 Chemical solution coating apparatus, 112 EUV exposure apparatus, 104 electrostatic chuck unit, 105, 405 back surface cleaning unit, 404 back surface defect inspection unit, 201 wafer.

Claims (5)

A chemical application unit for applying a chemical on the main surface of the substrate;
An inspection unit comprising an electrostatic chuck, and inspecting the adhesion state of foreign matter to the entire back surface by measuring the degree of adsorption between the back surface of the substrate and the electrostatic chuck;
A cleaning unit for cleaning the back surface;
A control unit for determining whether or not to carry the substrate out as a good product based on the degree of adsorption;
With
When the control unit determines that the substrate is not taken out as a non-defective product, the cleaning unit cleans the back surface. A chemical application unit for applying a chemical on the main surface of the substrate;
An inspection unit for inspecting the adhesion state of foreign matter on the entire back surface of the substrate;
A control unit for determining whether or not to carry the substrate out as a non-defective product based on an inspection result by the inspection unit;
The chemical | medical solution coating device characterized by the above-mentioned. The inspection unit includes an electrostatic chuck, measures the degree of adsorption between the back surface of the substrate and the electrostatic chuck,
The chemical liquid coating apparatus according to claim 2, wherein the control unit determines whether or not to carry the substrate out as a good product based on the degree of adsorption. The inspection unit includes a scanning unit that emits light or an electron beam to scan the back surface of the substrate, and a detection unit that detects the light or the electron beam reflected from the back surface,
3. The chemical solution coating apparatus according to claim 2, wherein the control unit determines whether or not to carry the substrate as a non-defective product based on a detection result of the detection unit. The chemical | medical solution coating device of any one of Claim 2 thru | or 4 further equipped with the washing | cleaning unit which wash | cleans the back surface of the said semiconductor substrate.

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