JP2006108463A - Exposure device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device that stabilizes the wafer temperature during exposure and shortens the time required for wafer transportation and an exposure method it employs. <P>SOLUTION: Because a board holder storing multiple above-mentioned boards is placed in a decompressed atmosphere so that the target board can be selected from the board holder for exposure, wafer temperature can be stabilized and set with high precision during exposure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used for lithography such as a semiconductor integrated circuit and a wafer loader for supplying a sensitive substrate (wafer) to such an exposure apparatus. In particular, the present invention relates to an exposure apparatus using a charged particle beam such as an electron beam or an ion beam, or an X-ray, which performs exposure in a reduced pressure atmosphere.

  In an apparatus that performs exposure in a reduced-pressure atmosphere such as an electron beam exposure apparatus, a wafer (sensitive substrate) is taken out from a cassette placed in the atmosphere and pre-aligned by a pre-aligner apparatus or the like, and then a load lock chamber. It is transported to a chamber or load chamber. A vacuum pump is attached to the load lock chamber, and the chamber can be evacuated. In the load lock chamber, a wafer is received from the pre-aligner under normal pressure, and after the chamber is evacuated, these are moved into the exposure apparatus.

  FIG. 3 is a plan view schematically illustrating a conventional example of a wafer loader for supplying a wafer from a cassette to an exposure apparatus. Arrows in the figure indicate wafer transfer paths. A wafer cassette 60 that accommodates a plurality of wafers, a first pre-aligner 71, and a robot arm 73 are arranged in the atmosphere. In the vicinity of the robot arm 73, a lamp 74 for heating the wafer is disposed.

  A gate valve 79 is provided at the entrance of the load lock chamber 77. The load lock chamber 77 is connected to the wafer vacuum load chamber 83 via the gate valve 81. A vacuum robot arm 85 is disposed in the chamber 83. Wafer vacuum load chamber 83 is connected to pre-aligner chamber 91 via gate valve 89. A second pre-aligner 93 is provided in the chamber 91. The wafer vacuum load chamber 83 is connected to the wafer chamber 106 of the exposure apparatus 100 via the gate valve 95. A wafer stage 131 is provided in the chamber 106, and a wafer holder 130 is provided on the stage 131.

  In order to transfer the wafer W from the cassette 60 into the exposure apparatus 100, first, one wafer is taken out from the cassette 60 by the robot arm 73 and transferred to the first pre-aligner 71. After pre-alignment is completed, the wafer W is taken out by the robot arm 73 and moved above the lamp 74. Then, the wafer is heated by irradiating the wafer with the lamp 74. Thereafter, the gate valve 79 is opened, the wafer W is transferred to the load lock chamber 77, the gate valve 79 is closed, and the load lock chamber 77 is evacuated. When the desired degree of vacuum is reached, the gate valve 81 on the vacuum load chamber 83 side is opened, the wafer is taken out by the vacuum robot arm 85, transferred to the pre-aligner chamber 91, and more accurate pre-alignment is performed by the second pre-aligner 93. Do. After the alignment is completed, the wafer is taken out by the vacuum robot arm 85, the gate valve 95 is opened, and the wafer is placed on the holder 130 on the wafer stage 131 in the wafer chamber 106.

  Normally, when the load lock chamber 77 is evacuated, the temperature of the wafer placed in the chamber is reduced by about 2 to 4 ° C. due to the adiabatic expansion of the gas. When the temperature decreases in this way, the wafer may be distorted by the temperature change. In one example, in a Si wafer having a diameter of 200 mm, a dimensional change of about 0.5 μm occurs with a temperature change of 1 ° C. Such a dimensional change makes it impossible to obtain a highly accurate pattern. Therefore, it is necessary to wait for several tens of minutes until the temperature rises to the original temperature, or to perform alignment again and again before exposure.

  Therefore, as described above, the wafer is preheated by the lamp 74 after the pre-alignment in the air is completed. As a result, when evacuating in the load lock chamber 77, even if the temperature of the wafer placed in the chamber decreases due to the adiabatic expansion of the gas, the temperature of the wafer returns to the original standard temperature. There is no dimensional change.

  However, in the above method, the temperature is only controlled in the atmosphere before the wafer is put into the load lock chamber. Therefore, if the transfer sequence is different from normal or it takes longer time than usual, the exposure will be performed. In some cases, an error occurs in the wafer temperature. Further, since the wafers are loaded one by one into the load lock chamber, and then the load lock chamber is depressurized or pressurized, the depressurization time and pressurization time required for the transfer per wafer become longer, and the wafer transfer It was difficult to increase the throughput of the system.

  The present invention has been made in view of the above problems, and provides an exposure apparatus and an exposure method that stabilize the temperature of a wafer at the time of exposure and further reduce the transfer time for transferring the wafer. It is aimed.

  In order to solve the above-mentioned problems, the present invention provides, firstly, an "exposure apparatus for forming a pattern on a substrate in a reduced pressure atmosphere, comprising a substrate holder for storing a plurality of the substrates in the reduced pressure atmosphere, wherein the substrate holder An exposure apparatus characterized in that a substrate to be processed is selected and exposed is provided. Thereby, the temperature of the wafer is stabilized, and the temperature of the wafer at the time of exposure can be managed with high accuracy.

  A second aspect of the present invention provides "the exposure apparatus according to claim 1, further comprising means for controlling the temperature of the substrate in the atmosphere" (claim 2). Thereby, the temperature of the wafer is stabilized, and the temperature of the wafer at the time of exposure can be managed with high accuracy.

  According to a third aspect of the present invention, there is provided an exposure apparatus according to claim 1 or 2, wherein means for storing a plurality of the substrates is provided in a load lock chamber used for loading and unloading the substrates. (Claim 3). As a result, it is possible to shorten the transfer time when transferring the wafer, and the throughput of the wafer transfer system can be greatly improved.

  According to a fourth aspect of the present invention, there is provided an exposure apparatus according to any one of claims 1 to 3, wherein the substrate holder substrate holder is provided with means for controlling the temperature of the substrate. . Thereby, the temperature of the wafer is stabilized, and the temperature of the wafer at the time of exposure can be managed with high accuracy.

  According to the present invention, fifthly, "the exposure apparatus according to claims 1 to 4, wherein the means for discriminating the identification mark marked on the substrate is provided in a reduced-pressure atmosphere" (claim 5). I will provide a. Thereby, it is possible to minimize the influence on the wafer processing process that can be performed when trouble occurs.

  In addition, the present invention provides a sixth "exposure method for forming a pattern on a substrate in a reduced-pressure atmosphere, wherein the substrate holder controls the temperature of the substrate in the atmosphere and stores a plurality of the substrates in the reduced-pressure atmosphere. An exposure method characterized in that a substrate to be processed is selected and exposed. Thereby, the temperature of the wafer is stabilized, and the temperature of the wafer at the time of exposure can be managed with high accuracy.

  In addition, according to the seventh aspect of the present invention, "the exposure method according to claim 6, wherein a plurality of the substrates are stored and then depressurized or pressurized in a load lock chamber used for loading and unloading the substrates". (Claim 7) is provided. As a result, it is possible to shorten the transfer time when transferring the wafer, and the throughput of the wafer transfer system can be greatly improved.

  As is apparent from the above description, according to the present invention, since the substrate holder for storing the wafer is provided in the reduced pressure atmosphere, the temperature of the wafer at the time of exposure can be stabilized with high accuracy. Further, in the load lock chamber used for loading and unloading the substrate, since a plurality of wafers are stored and then depressurized or pressurized, the transfer time for transferring the wafers can be shortened and the throughput of the transfer system can be improved. .

  Hereinafter, it demonstrates, referring drawings. FIG. 1 is a diagram schematically illustrating an exposure apparatus and an exposure method according to an embodiment of the present invention. FIG. 1A is a plan view of the entire exposure apparatus, and FIG. 1B is a partial side view. FIG. 2 is a diagram showing an outline of the imaging relationship and the control system in the entire optical system of the exposure apparatus of FIG.

  First, the configuration of the entire exposure apparatus will be described with reference to FIG. An optical barrel 101 is disposed on the electron beam exposure apparatus 100. A vacuum pump (not shown) is connected to the optical barrel 101, and the inside of the optical barrel 101 is evacuated.

  An electron gun 103 is disposed above the optical lens barrel (including the mask chamber) 101 and emits an electron beam downward. Under the electron gun 103, a condenser lens 104, an electron beam deflector 105, and a mask M are arranged in this order. The electron beam emitted from the electron gun 103 is converged by the condenser lens 104, and then sequentially scanned in the horizontal direction in the figure by the deflector 105, and each small region (subfield) of the mask M within the field of view of the optical system. ) Lighting is performed. The illumination optical system also has a beam shaping aperture, a blanking aperture, and the like (not shown).

  The mask M is fixed to the chuck 110 provided on the mask stage 111 by electrostatic adsorption or the like. The mask stage 111 is placed on the mount body 116. A driving device 112 shown on the left side of the drawing is connected to the mask stage 111. The driving device 112 is connected to the control device 115 via the driver 114. The mask stage 111 is provided with a laser interferometer 113 shown on the right side of the drawing. The laser interferometer 113 is connected to the control device 115. Accurate position information of the mask stage 111 measured by the laser interferometer 113 is input to the control device 115. Based on this, a command is sent from the control device 115 to the driver 114, and the drive device 112 is driven. In this way, the position of the mask stage 111 can be accurately feedback controlled in real time.

  Below the mount body 116, a wafer chamber 106 (vacuum chamber) is shown. A vacuum pump (not shown) is connected to the wafer chamber 106 to evacuate the chamber. A wafer transfer mechanism (wafer loader) including a vacuum load chamber 33, a load lock chamber 27, and the like is connected to the wafer chamber 106. This wafer transfer mechanism will be described later.

  A projection optical system barrel (not shown) in the wafer chamber 106 is provided with a projection lens 124, a deflector 125, and the like. Further, a wafer stage (precision device) 131 is placed on the bottom surface of the wafer chamber 106 below. A chuck 130 is provided above the wafer stage 131, and the wafer W is fixed by electrostatic adsorption or the like.

  The electron beam that has passed through the mask M is converged by the projection lens 124. The electron beam that has passed through the projection lens 124 is deflected by the deflector 125, and an image of the mask M is formed at a predetermined position on the wafer W. The projection optical system also has various aberration correction lenses, a contrast aperture (not shown), and the like.

  A driving device 132 shown on the left side of the drawing is connected to the wafer stage 131. The driving device 132 is connected to the control device 115 via the driver 134. The wafer stage 131 is provided with a laser interferometer 133 shown on the right side of the drawing. The laser interferometer 133 is connected to the control device 115. Accurate position information of the wafer stage 131 measured by the laser interferometer 133 is input to the control device 115. Based on this, a command is sent from the control device 115 to the driver 134, and the drive device 132 is driven. In this way, the position of the wafer stage 131 can be accurately feedback controlled in real time.

  Next, with reference to FIG. 1, a wafer transfer system of the exposure apparatus will be described. As shown in FIG. 1A, a wafer cassette (container) 10, a first pre-aligner 21, and a transfer robot arm 23 for storing a plurality of wafers are arranged in the atmosphere.

  As shown in FIG. 1A, the first pre-aligner 21 is disposed in the vicinity of the load lock chamber 27. A lamp 22 is disposed between the first pre-aligner 21 and the load lock chamber 27. A gate valve 29 is provided at the inlet of the load lock chamber 27. The load lock chamber 27 is connected to the wafer vacuum load chamber 33 via the gate valve 31. In the load lock chamber 27, storage means capable of storing a plurality of wafers W is arranged. A wafer transfer vacuum robot arm 35 is disposed in the wafer vacuum load chamber 33. The wafer vacuum load chamber 33 is connected to the pre-aligner chamber 41 via the gate valve 39. A second pre-aligner 43 is provided in the pre-aligner chamber 41.

  The wafer vacuum load chamber 33 is connected to the wafer chamber 106 of the exposure apparatus 100 via the gate valve 45. A wafer stage 131 is provided in the chamber 106, and a wafer holder 130 is provided on the wafer stage 131. The wafer vacuum load chamber 33 is provided with a wafer stocker 210. A shelf 215 is provided inside the wafer stocker 210 and can store a plurality of wafers W. A heater 217 is disposed below the wafer stocker 210, and a temperature sensor 219 capable of measuring the temperature of the wafer W or the temperature of the atmosphere is provided. Further, a wafer ID reader 212 is arranged inside the wafer stocker 210. The wafer ID reader 212 is preferably a bar code reader, a character OCR reader or the like.

  Next, the transfer procedure of the wafer W will be described. First, the wafer W is taken out from the cassette 10 by the wafer transfer robot arm 23. The wafer W is transferred to the first pre-aligner 21 and pre-alignment is performed. The pre-alignment time is about 4 seconds as an example. After completion of pre-alignment, the robot arm 23 takes out the wafer W from the first pre-aligner 21 and brings it onto the lamp 21. Here, the lamp 21 is irradiated to heat the wafer. Irradiation is stopped when the wafer temperature is 2 to 4 ° C. higher than the atmospheric temperature, for example. Next, the gate valve 29 is opened, and the wafer W is transferred to the load lock chamber 27 by the wafer transfer robot arm 23.

  Next, the same operation in which the wafer W is transferred to the load lock chamber 27 by the wafer transfer robot arm 23 is repeated. That is, the wafer W is taken out from the cassette 10 by the wafer transfer robot arm 23, and the wafer W is transferred to the first pre-aligner 21 for pre-alignment. Thereafter, the robot arm 23 takes out the wafer W from the first pre-aligner 21 and brings it onto the lamp 21. Here, the lamp 21 is irradiated to heat the wafer. Then, the wafer W is transferred to the load lock chamber 27 by the wafer transfer robot arm 23.

  When two wafers W are held in the load lock chamber 27 in this way, the gate valve 29 is closed and the load lock chamber 27 is evacuated. At this time, the temperature of the wafer W is lowered due to the adiabatic expansion of the gas, but since the temperature of the wafer is raised in advance, the wafer W becomes the original temperature even if the temperature is lowered. When the target vacuum degree is reached, the gate valve 31 on the wafer vacuum load chamber 33 side is opened, the wafer W is taken out from the load lock chamber 27 by the wafer transfer vacuum robot arm 35 in the wafer vacuum load chamber 33, and the vacuum load is loaded. The wafer is stored in the shelf 215 of the wafer stocker 210 provided in the chamber 33. At this time, since the wafer transfer vacuum robot arm 35 transfers the wafer W, only one wafer W can be transferred at a time, so the same operation is repeated twice. Thereafter, the gate valve 31 is closed.

  In this state, only two wafers W are stored on the shelf 215 of the wafer stocker 210. Although exposure may be started from this state, the wafer W is preferably transported from the cassette 10 to the wafer stocker 210 by the same procedure several times. Thus, the transferred wafer W is stored in the wafer stocker 210 for a while until exposure. In the wafer stocker 210, the temperature inside the wafer stocker 210 is accurately controlled by the heater 217 and the temperature sensor 219 below the wafer stocker 210. Therefore, the wafer W before being received by the wafer stocker 210 has a predetermined set temperature. Even if the temperature is not within the range, the temperature is adjusted to the temperature environment of the wafer stocker 210 and the temperature is close to a predetermined set temperature. In addition, since the temperature of the wafer vacuum load chamber 33 itself is strictly controlled, there is no need to provide a thermal barrier between the wafer stocker 210 and the wafer vacuum load chamber 33 to prevent heat transfer.

  When the number of wafers W reaches the wafer stocker 210, an actual exposure sequence is started. The gate valve 39 is opened, and the wafer W is transferred to the second pre-aligner 43 in the pre-aligner chamber 41 by the wafer transfer vacuum robot arm 35 to perform higher-precision pre-alignment. After the alignment is completed, the wafer is taken out by the wafer transfer vacuum robot arm 35, the gate valve 45 is opened, and the wafer is placed on the holder 130 on the wafer stage 131 in the wafer chamber 106. After the exposure operation is completed, the wafer W is taken out of the stage 131 by the wafer transfer vacuum robot arm 35 and returned to the wafer stocker 210.

  Next, the wafer W is transferred to the second pre-aligner 43 in the pre-aligner chamber 41 by the wafer transfer vacuum robot arm 35 in exactly the same procedure. After the alignment is completed, the wafer is taken out by the wafer transfer vacuum robot arm 35 and gated. The valve 45 is opened and placed on the holder 130 on the wafer stage 131 in the wafer chamber 106. After the exposure operation is completed, the wafer W is taken out of the stage 131 by the wafer transfer vacuum robot arm 35 and returned to the wafer stocker 210.

  In this state, there are two exposed wafers W placed on the wafer stocker 210. Thereafter, the gate valve 31 is opened, and two wafers W are sequentially transferred to the load lock chamber 27 by the wafer transfer vacuum robot arm 35. When the number of wafers W transferred to the load lock chamber 27 becomes two, the gate valve 31 is closed and the load lock chamber 27 is pressurized. When the load lock chamber 27 reaches atmospheric pressure, the gate valve 29 is opened, and two exposed wafers W are transferred by the wafer transfer robot arm 23 and returned to the cassette 10.

  Usually, exposure is performed in the sequence as described above, but troubles of the apparatus may occur. A countermeasure for such a case will be described. When trouble occurs in the apparatus, the wafer ID information stored in the exposure apparatus is often lost. When the wafer W is in the air, it is easy to obtain the wafer ID information again. However, when the wafer W is in the reduced pressure atmosphere, it is necessary to acquire the wafer ID information again under the reduced pressure atmosphere. .

  The wafer W stored in the wafer stocker 210 is transferred onto the wafer ID reader 212 by the wafer transfer vacuum robot arm 35, and the wafer ID information recorded on the wafer W is read. Based on this information, a wafer W processing process that minimizes the influence on the processing process of the wafer W is selected, and a restoration process is performed.

  In the above embodiment, the number of wafers stored in the load lock chamber 27 is two, but it is needless to say that the number may be three or more. In addition, the number of wafers W stored when depressurizing and when pressurizing are both stored two times, and then depressurization and pressurization are performed. However, the number of stored wafers is different when depressurizing and when pressurizing. I do not care.

  In the above-described embodiment, the load lock valves 39 and 45 connected to the wafer vacuum load chamber 33 are used. However, without using the load lock valve, the wafer vacuum load chamber 33 and the pre-aligner chamber 41 and It may be in communication with the electron beam exposure apparatus 100 chamber.

  In the above-described embodiment, the wafer stocker 210 shows that the temperature inside the wafer stocker 210 is controlled with high accuracy by the heater 217 and the temperature sensor 219 below the wafer stocker 210. The temperature sensor 219 may be simply stored without being disposed. Since the temperature of the wafer vacuum load chamber 33 itself is strictly controlled, the temperature of the wafer stocker 210 attached thereto is also controlled in a narrow temperature range. Therefore, the temperature of the wafer is managed with high accuracy over time even if it is simply stored.

  In the above-described embodiment, the temperature control is performed using the heater 217 and the temperature sensor 219. However, the temperature control may be performed using a temperature control plate. In this case, a plurality of temperature control plates are required to handle a plurality of wafers W. Further, the heater 217 may be anything as long as it can transmit radiant heat. Further, a plurality of heaters may be used for each of the plurality of wafers W.

FIGS. 1A and 1B are diagrams schematically illustrating an exposure apparatus according to an embodiment of the present invention, in which FIG. 1A is a plan view of the exposure apparatus, and FIG. FIG. 2 is a diagram showing an overview of an imaging relationship and a control system in the entire optical system of the exposure apparatus in FIG. 1. It is a top view which illustrates typically the conventional example of exposure apparatus.

Explanation of symbols

10 Wafer cassette 21 Pre-aligner 22 Lamp 23 Wafer transfer robot arm 27 Load lock chamber 29 Gate valve 33 Wafer vacuum load chamber 35 Wafer transfer vacuum robot arm 39 Gate valve 41 Pre-aligner chamber 43 Second pre-aligner 45 Gate valve 100 Electron beam exposure Device 101 Optical barrel 103 Electron gun 104 Condenser lens 105 Electron beam deflector 106 Wafer chamber 110 Chuck 111 Mask stage 112 Drive device 113 Laser interferometer 114 Driver 115 Controller 116 Mount body 124 Projection lens 125 Deflector 130 Chuck 131 Wafer stage 132 Drive Device 133 Laser Interferometer 134 Driver 211 Wafer Stocker 212 Wafer ID Reader 2 15 Shelf 217 Heater 219 Temperature sensor

Claims (7)

An exposure apparatus for forming a pattern on a substrate in a reduced-pressure atmosphere,
An exposure apparatus comprising a substrate holder for storing a plurality of the substrates in a reduced-pressure atmosphere, and selecting and exposing a substrate to be processed from the substrate holder. 2. The exposure apparatus according to claim 1, further comprising means for controlling the temperature of the substrate in the atmosphere. 3. The exposure apparatus according to claim 1, wherein a load lock chamber used for loading and unloading the substrate is provided with means for storing a plurality of the substrates. 4. The exposure apparatus according to claim 1, wherein the substrate holder is provided with means for controlling the temperature of the substrate. 5. An exposure apparatus according to claim 1, wherein means for discriminating the identification symbol marked on the substrate is provided in a reduced-pressure atmosphere. An exposure method for forming a pattern on a substrate in a reduced-pressure atmosphere,
An exposure method comprising controlling the temperature of the substrate in the atmosphere and selecting and exposing a substrate to be processed from the substrate holder storing a plurality of the substrates in a reduced-pressure atmosphere. The exposure method according to claim 6, wherein a plurality of the substrates are stored and then depressurized or pressurized in a load lock chamber used for loading and unloading the substrates.