JP2008292761A - Exposure apparatus and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus having excellent imaging performance and capable of carrying out an exposure process with high throughput even under high load exposure conditions. <P>SOLUTION: The exposure apparatus transfers a pattern formed on an original plate 3 onto a substrate 4 by exposure through a projection optical system 5. The exposure apparatus is equipped with a chamber 11 to house the projection optical system 5, and a temperature adjusting unit. The temperature adjusting unit includes a supply pipe 19 to supply a temperature controlled gas into the chamber 11, a discharge pipe 18 to discharge a gas from the chamber 11, and a controller 21 to control the gas supply and gas discharge. The controller 21 performs control so that the gas supply and gas discharge are not carried out during exposure but carried out in a non-exposure period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and a device manufacturing method. In particular, the present invention relates to a mirror projection type exposure apparatus used for projection exposure of a large glass substrate.

  In recent years, liquid crystal panels have been frequently used as display elements for word processors, personal computers, televisions and the like. A liquid crystal panel is manufactured by projecting a transparent thin film electrode on a glass substrate by photolithography. In this photolithography, a mirror projection type exposure apparatus using a projection optical system in which a concave reflecting surface and a convex reflecting surface are combined is used. Such an exposure apparatus is disclosed in Patent Document 1.

Patent Documents 2 and 3 disclose an exposure apparatus provided with an intake duct that supplies temperature-controlled air to the chamber of the projection optical system and an exhaust duct that exhausts air from the chamber. The exposure apparatus disclosed in Patent Document 2 stabilizes the optical characteristics of an aspheric lens by circulating a temperature-controlled helium gas in an aspheric unit having an aspheric lens in the projection optical system. The exposure apparatus disclosed in Patent Document 3 is controlled so that the temperature of the projection optical system is maintained at a predetermined temperature by temperature-controlled air when it is detected that the temperature in the chamber has deviated from the specified temperature.
Japanese Patent Laid-Open No. 7-57986 JP 11-67651 A JP 2001-244178 A

  When a liquid crystal panel is manufactured by a photolithography method using a mirror projection type exposure apparatus, it may be necessary to improve definition. In that case, by increasing the illumination intensity of the illumination system and decreasing the stage speed of the liquid crystal substrate, large energy (DOSE, exposure amount) may be given to the substrate per unit time. Hereinafter, such an exposure process is referred to as a high DOSE exposure process (high load exposure process, high energy incident process). In a high DOSE exposure process, a large thermal load is applied to the substrate. In the high DOSE exposure process, unlike the normal DOSE process, a large amount of heat is generated, so that the temperature state inside the lens barrel on which the projection optical system is mounted greatly increases. In particular, the temperature rise at the upper part of the lens barrel is more remarkable. As described above, in the high DOSE exposure process in which the temperature inside the lens barrel rises, there is a problem that the imaging performance, which has no problem in the normal DOSE process, deteriorates, such as distortion.

  Further, since the exposure apparatus described in Patent Document 2 circulates a temperature-controlled helium gas even during exposure, the optical element may vibrate due to the gas flow, which may deteriorate the imaging performance.

  Furthermore, in the exposure apparatus described in Patent Document 3, the temperature of the projection optical system is controlled when it is detected that the temperature in the chamber has deviated from the specified temperature. Therefore, during exposure and during non-exposure (such as when the substrate is replaced). As a result, the overall throughput of the exposure process was insufficient.

  An object of the present invention is to provide an exposure apparatus that can perform exposure processing with excellent imaging performance and high throughput even under high load exposure conditions.

  The present invention relates to an exposure apparatus that exposes and transfers a pattern formed on an original plate to a substrate via a projection optical system, and supplies a chamber containing the projection optical system and a temperature-controlled gas inside the chamber. A temperature control unit including a controller for controlling gas supply and gas discharge, and the controller does not perform gas supply and gas discharge at the time of exposure. Control is performed so that it is performed during exposure.

  According to the present invention, it is possible to provide an exposure apparatus that can perform exposure processing with excellent imaging performance and high throughput even under high load exposure conditions.

[Embodiment of exposure apparatus]
An example of the exposure apparatus according to the present invention will be described with reference to FIG. The exposure apparatus of this embodiment is a mirror projection type scanning exposure apparatus for manufacturing a liquid crystal panel.

  The pattern formed on the original plate (mask) 3 illuminated by the illumination system 1 passes through the optical thin body 6, the reflection mirror 7, the concave mirror 8, the convex mirror 9, the concave mirror 8, the reflection mirror 7, and the optical thin body 6 again. (Glass substrate, glass plate) 4 is imaged and exposed and transferred. In this state, the original 3 and the substrate 4 are scanned, and all the patterns formed on the original 3 are transferred to the substrate 4. The alignment scope 2 detects an alignment mark between the original 3 and the substrate 4. The two optical thin bodies 6, the reflection mirror 7, the concave mirror 8, and the convex mirror 9 are optical elements constituting the projection optical system (mirror optical system) 5. Of the optical elements constituting the projection optical system 5, the reflecting mirror 7, the concave mirror 8 and the convex mirror 9 have an optical axis extending in a direction intersecting the vertical direction. The projection optical system 5 is accommodated in a chamber (lens barrel).

  As the material of the reflecting mirror 7, the concave mirror 8, and the convex mirror 9, in order to avoid the influence on the imaging performance even when the internal temperature of the chamber rises, a highly stable glass having a small thermal expansion coefficient, for example, a zero dua made of shot (Registered trademark) or the like may be used.

  The exposure apparatus includes a temperature adjusting unit including a supply pipe for supplying a temperature-controlled gas into the chamber, a discharge pipe for discharging the gas from the chamber, and a controller 21 for controlling the gas supply and gas discharge. Yes. The structure of the chamber (lens barrel) including the supply pipe and the discharge pipe will be described using two examples.

(First example)
A first example of the structure of the chamber 11 will be described with reference to FIG. In FIG. 1, a locus of exposure light passing through the projection optical system 5 is shown as a light beam 12. In order to guarantee the performance of the chamber 11 and other components of the exposure apparatus (the illumination system 1, the alignment scope 2, the original stage that holds and moves the original, the substrate stage that holds and moves the substrate, etc.) Generally, it is installed in a temperature control chamber (not shown).

  When the process of high DOSE exposure is performed in such a chamber 11, the internal temperature of the chamber 11 becomes higher than that during normal DOSE exposure. This is because the energy of light incident on the optical elements included in each projection optical system 5 increases, and the warmed optical elements warm the surrounding air. In particular, since warm air moves upward, the temperature of the gas, for example air, inside the chamber 11 is higher than below. In such a state, the refractive index of the gas whose temperature has risen changes, and the imaging performance may be deteriorated due to the influence as compared with the normal DOSE process. In particular, the projection optical system 5 in the mirror projection type exposure apparatus includes a concave mirror 8 and a convex mirror 9 which are optical elements having optical axes extending in a direction intersecting a vertical direction which is an incident direction and an outgoing direction of exposure light. Therefore, the temperature difference between the upper and lower sides in the vertical direction inside the chamber 11 affects the temperature difference in the vertical direction between the concave mirror 8 and the convex mirror 9, and the deterioration of the imaging performance due to the image height becomes remarkable.

  The thing located in the upstream of the optical path of the optical element installed in the chamber 11, ie, the upper part in the chamber 11, is warmed more strongly than the thing located in the lower part in the chamber 11. Further, the air heated through the optical element rises to the upper part in the chamber 11. In the first example, a discharge pipe 18 for discharging warmed air in the chamber 11 is connected to the upper part of the chamber 11, and a supply pipe 19 for supplying air for lowering the temperature in the chamber 11 is provided in the chamber 11. Connected to the bottom. That is, in the first example, the discharge port 14 of the discharge tube 18 and the supply port 15 of the supply tube 19 are provided on the wall surface of the chamber 11, and the discharge port 14 is disposed above the supply port 15. The discharge port 14 and the supply port 15 are provided in two places in the first example, but may be one place or three places or more.

  In the first example, the supplied gas and the exhausted gas are air, but other gases such as an inert gas may be used as long as the temperature inside the chamber 11 is lowered without adversely affecting the projection optical system 5. Can be used.

  For example, if the heated air is only discharged through the discharge port 14, the inside of the chamber 11 becomes a negative pressure with respect to the outside of the chamber 11, which causes fogging of the optical elements and the like constituting the projection optical system 5. May be drawn into the chamber 11. Therefore, the air pressure inside the chamber 11 needs to be positive with respect to the external air pressure. That is, the flow rate of the supplied air must be greater than or equal to the flow rate of the discharged air.

  Furthermore, the temperature of the air supplied into the chamber 11 through the supply port 15 needs to be adjusted. The temperature is preferably a reference temperature that guarantees the performance of the exposure apparatus. Air can be supplied through a chiller (not shown) that can keep the temperature constant. Further, regarding a method of introducing air through the supply port 15, a method of branching from a fan (not shown) or an air outlet of a temperature control chamber surrounding the chamber 11 can be considered. Regarding the method of exhausting the warmed air 13 existing in the upper part of the chamber 11 from the exhaust port 14, there is a method of connecting to a fan (not shown) or an air recovery port of the temperature control chamber surrounding the chamber 11. Conceivable.

  The temperature in the chamber 11 is preferably maintained within a range of about 23.0 ° C to 23.2 ° C, for example. Therefore, the exposure apparatus preferably includes a sensor 20 that detects the temperature of air in the chamber 11 and a controller 21 that controls the supply flow rate and the discharge flow rate of air according to the detected temperature. The sensor 20 can be disposed, for example, in the vicinity of the outlet 14 where warmed air exists. The sensor 20 and the controller 21 constitute a temperature control unit together with the discharge pipe 18 and the supply pipe 19.

  Next, the timing for supplying and discharging air will be described with reference to FIG. FIG. 4 schematically shows the relationship between the time lapse of the exposure process and the temperature state in the chamber 11. When the high DOSE exposure process is performed, the temperature in the chamber 11 rises with time. If the air is not replaced, the temperature in the chamber 11 enters an abnormal temperature range that adversely affects the imaging performance. On the other hand, when the air is replaced when the substrates are replaced, the temperature in the chamber 11 can be kept within a normal temperature range that is normal in imaging performance.

  The controller 21 controls the timing so that air replacement, that is, gas supply and gas discharge, is not performed during exposure when the pattern is transferred to the substrate but during non-exposure such as when the substrate is replaced. Note that the non-exposure time can include not only the time when the substrates are replaced, but also when the exposure operation is waiting between the lots when processing a plurality of lots of substrates. If air is replaced during exposure in the high DOSE exposure process, vibrations of a fan (not shown) connected to the chamber 11 may propagate to the projection optical system 5 and adversely affect imaging performance. It is preferable to exchange air during non-exposure.

(Second example)
FIG. 2 is a diagram illustrating a second example of the structure of the chamber 11. The second example is effective when the temperature of a specific portion in the chamber 11 becomes high during the high DOSE exposure process and adversely affects the imaging performance.

  For example, when it is known that the air temperature above the convex mirror 9 becomes high during the high DOSE exposure process, the discharge pipe 18 is disposed inside the chamber 11 so that the funnel-shaped discharge port 14 is located in the vicinity (upper side) of the convex mirror 9. Including an extension that extends to Since the discharge port 14 has a funnel shape, it temporarily receives the air 16 whose temperature has increased. With such a configuration, the air 16 heated above the convex mirror 9 is efficiently discharged from the chamber 11 through the funnel-shaped discharge port 14 and the discharge pipe 18. In the second example, it is assumed that heating is performed above the convex mirror 9 in particular. However, when the air is particularly warmed above other optical elements, such as the concave mirror 8 and the reflecting mirror 7, a discharge pipe extended into the chamber 11 so that a funnel-shaped discharge port 14 is located there. What is necessary is just to move 18 extension parts. Of course, the discharge pipe 18 and the supply pipe 19 including the funnel-shaped discharge port 14 must be arranged so as not to block the exposure light. In this example, the sensor 20 is provided in the vicinity of the discharge port 14.

  The shape and arrangement position of the supply port 15 for supplying air can also be provided in the same manner as the discharge port 14. For example, when it is known that the upper part of the convex mirror 9 is particularly warmed, the supplied air may be blown against the convex mirror 9 itself while also cooling the convex mirror 9 itself.

  The discharge pipe 18 and the supply pipe 19 are preferably made of a material that generates less gas in order to avoid problems such as fogging of the optical elements inside the chamber 11.

  By making the structure of the chamber of the exposure apparatus as in the first example and the second example, it is possible to obtain predetermined imaging performance without abnormally increasing the temperature inside the chamber 11.

[Device Manufacturing Embodiment]
Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 5 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, liquid crystal panels, LCDs, CCDs, etc.). Here, a semiconductor chip manufacturing method will be described as an example.
In step S1 (circuit design), a semiconductor device circuit is designed. In step S2 (mask production), an original plate (mask) is produced based on the designed circuit pattern. In step S3 (substrate manufacture), a substrate is manufactured using a material such as silicon. Step S4 (substrate process) is called a pre-process, and an actual circuit is formed on the substrate using the original (mask) and the substrate by the above exposure apparatus using the lithography technique. Step S5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the substrate manufactured in step S4. The assembly process includes an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. In step S6 (inspection), inspections such as an operation check test and a durability test of the semiconductor device manufactured in step S5 are performed. Through these steps, the semiconductor device is completed and shipped (step S7).
FIG. 6 is a detailed flowchart of the substrate process in step S4. In step S11 (oxidation), the surface of the substrate is oxidized. In step S12 (CVD), an insulating film is formed on the surface of the substrate. In step S13 (electrode formation), an electrode is formed on the substrate by vapor deposition. In step S14 (ion implantation), ions are implanted into the substrate. In step S15 (resist process), a photosensitive agent is applied to the substrate. In step S16 (exposure), the circuit pattern of the original (mask) is transferred to the substrate by the exposure apparatus. In step S17 (development), the substrate to which the pattern is transferred is developed. In step S18 (etching), portions other than the developed resist image are removed. In step S19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the substrate.

The figure explaining an example of a chamber. The figure explaining the other example of a chamber. The figure explaining the structure of exposure apparatus. The figure for demonstrating the temperature change in a chamber. The flowchart for demonstrating manufacture of the device using an exposure apparatus. 6 is a detailed flowchart of a substrate process in step S4 of the flowchart shown in FIG.

Explanation of symbols

1: illumination system, 2: alignment scope, 3: original plate (mask), 4: substrate, 5: projection optical system (mirror optical system), 6: optical thin body, 7: reflection mirror, 8: concave mirror, 9: convex mirror 11: chamber (lens), 12: luminous flux, 13: gas (air) with increased temperature, 14: discharge port, 15: supply port, 16: gas (air) with increased temperature above the convex mirror, 17: funnel shape 18: discharge pipe, 19: supply pipe, 20: sensor, 21: controller

Claims (8)

An exposure apparatus that exposes and transfers a pattern formed on an original to a substrate via a projection optical system,
A chamber containing the projection optical system;
A temperature adjusting unit including a supply pipe for supplying a temperature-controlled gas to the inside of the chamber, a discharge pipe for discharging the gas from the inside of the chamber, and a controller for controlling the gas supply and gas discharge,
The exposure apparatus is characterized in that the gas supply and the gas discharge are controlled not to be performed during exposure but to be performed during non-exposure.   The exposure apparatus according to claim 1, wherein the discharge port of the discharge pipe is disposed above the supply port of the supply pipe.   The at least one of the supply pipe and the discharge pipe includes an extension extending to an optical element constituting the projection optical system housed in the chamber. The exposure apparatus described.   2. The projection optical system according to claim 1, wherein the projection optical system emits exposure light incident in a vertical direction in the vertical direction, and includes an optical element having an optical axis extending in a direction intersecting the vertical direction. The exposure apparatus according to any one of claims 3 to 3.   The exposure apparatus according to claim 1, wherein the supply pipe and the discharge pipe are arranged so as not to block exposure light. A sensor for detecting a temperature at a discharge port of the discharge pipe,
6. The exposure apparatus according to claim 1, wherein the controller controls a gas supply flow rate and a discharge flow rate in accordance with a temperature detected by the sensor.   7. The controller according to claim 1, wherein the controller controls the gas supply and the gas discharge so as to be performed when the substrate is replaced or when an exposure operation is waited. 2. The exposure apparatus according to item 1. Using the exposure apparatus according to any one of claims 1 to 7, a step of exposing and transferring a pattern formed on an original to a substrate;
And a step of developing the substrate on which the pattern is exposed and transferred.

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