JP5146417B2 - Exposure equipment - Google Patents

Description

  The present invention relates to an exposure apparatus that projects a photomask pattern onto a wafer.

  Patent Document 1 discloses an exposure apparatus having a wafer stage, an optical system unit, and a frame that supports the wafer stage and the optical system unit. The optical system unit projects the photomask pattern onto the wafer on the wafer stage. When exposure is performed by the exposure apparatus, it is necessary to make the temperature distribution in the exposure apparatus uniform. This is because if the temperature distribution becomes non-uniform, distortion occurs due to the temperature characteristics (that is, expansion and contraction) of the dimensions of each part, and the positional relationship between the optical system unit and the wafer stage is shifted. If this positional relationship is deviated, the pattern cannot be accurately projected onto the wafer. In the exposure apparatus of Patent Document 1, a frame supports a wafer stage (hereinafter referred to as a wafer stage support portion), an optical system unit (hereinafter referred to as an optical system unit support portion), and a wafer stage support. It is comprised by the part (henceforth a connection part) which connects a part and an optical system unit support part. And the flow path is provided in the optical system unit support part, The fluid which adjusted the temperature is distribute | circulated in this flow path. Thereby, the temperature of the optical system unit support part is made uniform, and distortion of the optical system unit support part is prevented.

JP-A-9-320927

  When the temperature non-uniformity occurs in the optical system unit support portion of the frame, the high temperature portion becomes larger in size than the low temperature portion, so that a parallel position shift occurs in which the wafer stage and the optical system unit relatively move in parallel. In the exposure apparatus disclosed in Patent Document 1, since the temperature of the optical system unit support is uniformized, this parallel displacement can be suppressed. However, even if the temperature of the optical system unit support is made uniform, there may be an angular deviation in which the relative posture between the wafer stage and the optical system unit changes. When the angle shift occurs, the incident angle of the light beam with respect to the wafer is shifted, and the pattern cannot be projected onto the wafer with an accurate scale. The translational displacement described above can be corrected to some extent by adjusting the position of the wafer stage, but the angular displacement is a serious problem because it is difficult to correct. In the exposure apparatus of Patent Document 1, there is a problem that the angle deviation cannot be suppressed.

  In view of the above-described circumstances, the present specification provides an exposure apparatus that can suppress angular deviation between a wafer stage and an optical system unit.

The present inventor has found that the cause of the angle deviation is in the connection portion connecting the optical system unit support portion and the wafer stage support portion in the frame. In other words, if the length of the connection portion varies depending on the position due to the nonuniform temperature of the connection portion, the optical system unit support portion is inclined with respect to the wafer stage support portion. As a result, an angle shift occurs between the wafer stage and the optical system unit.
Therefore, the exposure apparatus provided by this specification has the following configuration. The exposure apparatus includes a wafer stage, an optical system unit, a frame, and a fluid supply unit. A wafer is placed on the wafer stage. The optical system unit projects the photomask pattern onto the wafer on the wafer stage. The frame supports the wafer stage and the optical system unit. The frame includes a wafer stage support unit that supports the wafer stage, an optical system unit support unit that supports the optical system unit above the wafer stage, and a plurality of first units that connect the wafer stage support unit and the optical system unit support unit. It has a columnar part. A first flow path extending along the first columnar part is formed inside each first columnar part. The fluid supply means circulates the fluid in each first flow path.
In this exposure apparatus, a first flow path is formed in each first columnar section connecting the wafer stage support section and the optical system unit support section, and the fluid supply means circulates the fluid through each first flow path. For this reason, the temperature of each 1st columnar part is equalized with the fluid which flows through each 1st flow path. That is, the temperature difference between the first columnar portions is extremely small. For this reason, the angular deviation between the wafer stage and the optical system unit is suppressed.

Generally, an exposure apparatus has a mask stage that holds a photomask. Even when an angle deviation occurs between the mask stage and the optical system unit, the pattern cannot be projected onto the wafer with an accurate scale.
Therefore, the exposure apparatus described above preferably has the following configuration. In this exposure apparatus, the frame further includes a mask stage that holds the photomask above the optical system unit, and a plurality of second columnar portions that connect the mask stage and the optical system unit support. A second flow path that extends along the second columnar section and is connected to the first flow path is formed inside each second columnar section. The fluid supply means circulates the fluid in the channel formed by the first channel and the second channel.
In this exposure apparatus, the fluid also flows through the second flow path inside each second columnar portion that connects the mask stage support portion and the optical system unit support portion, so that a temperature difference occurs between each second columnar portion. This is also suppressed. For this reason, the angle shift between the mask stage and the optical system unit is also suppressed.

In the above-described exposure apparatus, it is preferable that a third flow path extending along the periphery of the optical system unit and connected to the first flow path is formed inside the optical system unit support. And it is preferable that a fluid supply means distribute | circulates the fluid in the flow path formed of the 1st flow path and the 3rd flow path.
According to such a configuration, the temperature distribution of the optical system unit support is made uniform, and parallel position deviation between the wafer stage and the optical system unit is also suppressed.

1 is a diagram showing a schematic configuration of an exposure apparatus 10 according to an embodiment. FIG. 3 is a schematic perspective view of the exposure unit 14. The figure which shows schematic structure of the exposure apparatus of a modification. The figure which shows schematic structure of the exposure apparatus of a modification.

  An exposure apparatus according to the embodiment will be described. FIG. 1 shows a schematic configuration of an exposure apparatus 10 of the embodiment. As shown in FIG. 1, the exposure apparatus 10 includes a chamber 12, an exposure unit 14 installed in the chamber 12, and a temperature controller 35 installed outside the chamber 12. The exposure apparatus 10 includes an air conditioner (not shown) and a projector (not shown).

  Air whose temperature is adjusted by an air conditioner (not shown) is sent into the chamber 12. For this reason, the temperature in the chamber 12 is controlled to a substantially constant temperature (about 23 ° C. in the present embodiment). FIG. 2 is a schematic perspective view of the exposure unit 14. As shown in FIGS. 1 and 2, the exposure unit 14 includes a wafer stage 16, an optical system unit 18, and a frame 20. The frame 20 is disposed above the wafer stage support unit 22 formed at the bottom, the optical system unit support unit 24 disposed above the wafer stage support unit 22, and the optical system unit support unit 24. The mask stage 26 is provided. The frame 20 has three columnar portions 28 to 30. In FIG. 1, the columnar portion 30 is not shown in consideration of the visibility of the drawing. Each columnar section 28-30 connects the wafer stage support section 22, the optical system unit support section 24, and the mask stage 26 to each other.

  A wafer stage 16 is fixed on the wafer stage support 22. A semiconductor wafer is placed on the wafer stage 16. The wafer stage 16 is an XY stage that can move along two axes in a horizontal plane.

  A through hole is formed in the center of the optical system unit support 24. The optical system unit 18 is placed on the optical system unit support 24 in a state of being inserted through the through hole. The optical system unit 18 is composed of a plurality of lenses. The optical system unit 18 is fixed to the optical system unit support 24 so that the optical axis thereof is perpendicular to the wafer stage 16. The optical system unit 18 reduces the pattern of a reticle (an example of a photomask) attached to the mask stage 26 and projects it onto a semiconductor wafer on the wafer stage 16.

  At the center portion of the mask stage 26, a reticle placing portion 27 made of transparent glass is formed. The reticle placing portion 27 is formed at a position directly above the optical system unit 18. In reticle mounting unit 27, light can be transmitted from the upper surface side to the lower surface side. The reticle placing unit 27 is formed in parallel (that is, horizontally) with the wafer stage 16. For this reason, the reticle mounting portion 27 is disposed perpendicular to the optical axis of the optical system unit 18. A reticle on which a pattern to be projected onto the semiconductor wafer is formed is placed on the reticle placement unit 27.

  When projecting a reticle pattern onto a semiconductor wafer, a semiconductor wafer coated with a photoresist on the surface is placed on the wafer stage 16, and the reticle is placed on the reticle placement unit 27. Then, light is irradiated from the upper side toward the reticle (that is, vertically downward) by a projector (not shown). Then, the light transmitted through the reticle enters the optical system unit 18, and an image obtained by reducing the reticle pattern is projected (formed) on the semiconductor wafer by the optical system unit 18. By exposing the semiconductor wafer in this way, a resist mask can be formed in a shape corresponding to the projected pattern.

  When exposure is performed by the exposure apparatus 10, it is necessary to strictly control the temperature in order to ensure exposure accuracy. As described above, the temperature in the chamber 12 is maintained at about 23 ° C. However, even if temperature management is performed in this way, it is difficult to make the temperature of the frame 20 uniform. If the temperatures of the three columnar portions 28 to 30 of the frame 20 are different, the lengths of the columnar portions are different from each other due to the effects of thermal expansion and contraction due to the temperature difference. As a result, the optical system unit support part 24 and the mask stage 26 are inclined with respect to the horizontal plane, and the optical axis of the optical system unit 18 is inclined with respect to the wafer stage 16 and the reticle mounting part 27. For example, if the length of the part connecting the wafer stage support part 22 and the optical system unit support part 24 in the columnar part (hereinafter referred to as the first columnar part) differs between the columnar parts due to temperature nonuniformity, the wafer The optical axis of the optical system unit 18 is inclined with respect to the stage 16. Further, if the length of the part connecting the optical system unit support part 24 and the mask stage 26 in the columnar part (hereinafter referred to as the second columnar part) differs between the columnar parts due to temperature nonuniformity, the optical system unit The reticle mounting portion 27 is inclined with respect to the 18 optical axes. As described above, when an inclination occurs between each part and the optical axis of the optical system unit 18, the exposure accuracy decreases. The exposure apparatus 10 of this embodiment has a mechanism for equalizing the temperatures of the columnar portions 28 to 30 in order to prevent a decrease in accuracy caused by a difference in temperature of the columnar portions 28 to 30.

  As shown in FIG. 2, a flow path 40 is formed inside the columnar portion 28. The channel 40 is formed from the first columnar portion 28a to the second columnar portion 28b. One end of the channel 40 is connected to an opening 40a formed on the side surface of the upper end portion of the second columnar portion 28b, and the other end of the channel 40 is formed on the side surface of a substantially middle portion of the first columnar portion 28a. Connected to the opening 40b. A flow path 41 is formed inside the columnar portion 29. The channel 41 is formed from the first columnar portion 29a to the second columnar portion 29b. One end of the flow channel 41 is connected to an opening 41a formed on the side surface of the upper end portion of the second columnar portion 29b, and the other end of the flow channel 41 is formed on the side surface of a substantially middle portion of the first columnar portion 29a. Connected to the opening 41b. A flow path 42 is formed inside the columnar portion 30. The channel 42 is formed from the first columnar portion 30a to the second columnar portion 30b. One end of the channel 42 is connected to an opening 42a formed on the side surface of the upper end portion of the second columnar portion 30b, and the other end of the channel 42 is formed on the side surface of the lower end portion of the first columnar portion 30a. It is connected to the opening 42b.

  The temperature controller 35 is connected to the flow paths 40, 41, 42 by pipes 43, 44. That is, the temperature controller 35 is connected to the openings 40a, 41a, and 42a by the upstream pipe 43, and is connected to the openings 40b, 41b, and 42b by the downstream pipe 44. The temperature controller 35 sends out air from the downstream pipe 44 toward the upstream pipe 43. For this reason, air circulates in the circulation path constituted by the upstream pipe 43, the flow paths 40, 41, 42 and the downstream pipe 44. Further, the temperature adjuster 35 adjusts the air flowing into the temperature adjuster 35 from the downstream pipe 44 to a temperature closer to the target temperature, and sends the air to the upstream pipe 43. In this embodiment, the target temperature is set to 23 ° C. which is equal to the temperature in the chamber 12. For this reason, air whose temperature is adjusted to about 23 ° C. (more specifically, 23 ° C. ± 0.3 ° C.) flows in the flow paths 40, 41, 42.

  When exposure is performed by the exposure apparatus 10, the temperature controller 35 is operated, and air whose temperature is adjusted to about 23 ° C. is circulated in the flow paths 40, 41, 42. For this reason, the temperature of the three columnar parts 28-30 is maintained at about 23 degreeC. Thereby, the temperature difference between the three columnar portions 28 to 30 becomes extremely small, and the deterioration of the exposure accuracy is prevented.

  Further, in the exposure apparatus 10, the columnar portions 28 and 29 are formed to be slightly inclined with respect to the vertical direction, whereby the interval between the columnar portions 28 and 29 becomes smaller toward the upper side. For this reason, the sizes of the optical system unit support 24 and the mask stage 26 are smaller than the wafer stage support 22. As described above, since the sizes of the optical system unit support 24 and the mask stage 26 are small, even when thermal expansion or contraction occurs in the optical system unit support 24 and the mask stage 26, the dimensional change amount is not so large. . Thus, in the exposure apparatus 10, the exposure accuracy is also improved by suppressing changes in the dimensions of the optical system unit support 24 and the mask stage 26.

  In the exposure apparatus 10 of the above-described embodiment, the flow path is formed only inside the columnar portions 28, 29, and 30 of the frame 20. However, a flow path may be formed in the optical system unit support section 24, the wafer stage support section 22, or the mask stage 26, and the temperature-adjusted air may be circulated in the flow path. For example, as shown in FIG. 3, a flow path 43 extending along the periphery of the optical system unit 18 and communicating with the flow paths 40 to 42 may be formed inside the optical system unit support 24. it can. As a result, the temperature of the optical system unit support 24 can be made uniform. Further, as shown in FIG. 4, each flow path may be extended to the inside of the wafer stage support portion 22. As a result, the temperature of the wafer stage support 22 can also be made uniform.

  In the above-described embodiment, air is circulated in the flow path, but various gases and liquids can be used as the fluid circulated in the flow path.

  In the above-described embodiment, the air conditioner that sends air into the chamber 12 and the temperature controller 35 are provided separately. However, the temperature controller 35 may send air into the chamber 12. . That is, the temperature controller 35 can also function as an air conditioner that adjusts the temperature in the chamber 12 by allowing air to flow through the flow path in the columnar portion and also sending air into the chamber 12. .

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10: exposure apparatus 12: chamber 14: exposure unit 16: wafer stage 18: optical system unit 20: frame 22: wafer stage support unit 24: optical system unit support unit 26: mask stage 27: reticle mounting unit 28: columnar unit 28a: first columnar portion 28b: second columnar portion 29: columnar portion 29a: first columnar portion 29b: second columnar portion 30: columnar portion 30a: first columnar portion 30b: second columnar portion 35: temperature controller 40 : Channel 41: Channel 42: Channel

Claims (3)

A wafer stage on which the wafer is placed;
An optical unit that projects a photomask pattern onto a wafer on a wafer stage; and
A frame for supporting the wafer stage and the optical system unit;
Fluid supply means,
An exposure apparatus comprising:
The frame includes a wafer stage support unit that supports the wafer stage, an optical system unit support unit that supports the optical system unit above the wafer stage, and a plurality of first units that connect the wafer stage support unit and the optical system unit support unit. It has a columnar part,
A first flow path extending along the first columnar part is formed inside each first columnar part,
An exposure apparatus, wherein the fluid supply means circulates a fluid in each first flow path. The frame further includes a mask stage that holds the photomask above the optical system unit, and a plurality of second columnar portions that connect the mask stage and the optical system unit support.
Inside each second columnar part, a second flow path extending along the second columnar part and connected to the first flow path is formed,
2. The exposure apparatus according to claim 1, wherein the fluid supply means circulates the fluid in the flow path formed by the first flow path and the second flow path. Inside the optical system unit support portion, a third flow path extending along the periphery of the optical system unit and connected to the first flow path is formed.
The exposure apparatus according to claim 1, wherein the fluid supply means circulates a fluid in a flow path formed by the first flow path and the third flow path.

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