JP2007027546A - Immersion exposure equipment - Google Patents

Abstract

Provided is an immersion type exposure apparatus that enables immersion exposure with less contamination of impurities by supplying standard water such as city water from factory equipment and newly providing pure water and ultrapure water generation means. To do.
An immersion type exposure apparatus that fills the lowermost surface of a projection optical system and an exposure light passage space between wafers with ultrapure water and performs exposure in a state where the exposure light passage space is filled with ultrapure water. Provided with pure water generating means for generating pure water from water. According to the present invention, it is possible to provide an immersion type exposure apparatus with little deterioration in image performance by reducing the mixing of ions and particles into ultrapure water which is an immersion liquid used for immersion exposure. In addition, it is possible to provide an environment in which immersion exposure can be performed even in an installation location that does not have ultrapure water supply means.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor manufacturing apparatus, and in particular, a liquid that has a nozzle that fills the exposure light passage space between the bottom surface of a projection optical system and a wafer substrate with liquid and that performs exposure in a state where the exposure light passage space is filled with liquid. The present invention relates to liquid temperature control of an immersion type exposure apparatus.

  A schematic view of a conventional exposure apparatus is shown in FIG.

  In FIG. 3, reference numeral 31 denotes a light source of an exposure apparatus used for semiconductor manufacturing. The light source 31 is shifted from an i-line to an excimer laser as the wavelength of the exposure pattern becomes finer as the exposure pattern becomes finer. The light source has also shifted from KrF to ArF. Currently, the use of F2 laser and EUV light is being studied in order to satisfy the demand for further miniaturization.

  The light emitted from the light source 31 is sent to the illumination optical system 33 through the introduction unit 32. The illumination optical system 33 removes illuminance unevenness and forms a beam to become illumination light, which is irradiated onto a reticle 34 which is an original of an exposure pattern. The reticle 34 is disposed on the reticle stage 35.

  The light that has passed through the reticle 34 becomes pattern light and is reduced and projected onto a wafer 37 disposed on an optically conjugate plane with the reticle 34 via a projection optical system 36.

  The wafer 37 is placed on a linear motor-driven wafer stage 38 and is repeatedly exposed by step-and-repeat. As the integrated circuit line width becomes finer, the reticle stage 35 is also driven by a linear motor, and the wafer stage 38 and the reticle stage 35. A semiconductor exposure apparatus has been developed in which exposure is performed while narrowing and scanning an exposure area in a slit shape at the center of a projection optical system 36 that can perform optimal image formation in synchronization with each other.

  In recent years, attention has been paid to an immersion type exposure apparatus that performs exposure in a state where the space between the lowermost surface of the projection optical system 36 and the wafer 37 is filled with a liquid such as pure water. By achieving immersion, the NA can be increased due to the high refractive index of the liquid. This means that a path to further miniaturization can be easily opened by adding a liquid immersion apparatus based on an existing ArF exposure apparatus without using an F2 or EUV light source having a large equipment load.

  FIG. 2 shows a configuration in the case of performing local liquid immersion as an example of the form of the liquid immersion type exposure apparatus.

  An immersion liquid supply / discharge device 41 is provided on the lowermost surface of the projection optical system 36 to create an immersion area. A fixed amount of immersion liquid is supplied from the supply nozzle 42 by the immersion liquid supply / discharge apparatus 41, and the immersion area is set up. Fill with immersion liquid. A method of performing exposure in this state is immersion exposure.

  The liquid used for immersion can be said to be a part of the optical component, and strict purity and temperature control are required. Normally, ultrapure water is used, and the ultrapure water generated in the factory equipment is temperature-controlled by the heat exchanger 45 via the supply line 44 and supplied to the liquid immersion area via the supply nozzle 42. The ultrapure water sent to the immersion area is drained to the outside through the discharge port 43 and the drain line 46 of the immersion liquid supply / discharge device 41.

  However, if the distance from the ultrapure water generator in the factory equipment to the exposure device is long, impurities such as particles and ions are mixed into the ultrapure water for immersion exposure, which is fatal to the imaging performance of immersion exposure. Can give a blow. Further, there may be a case where there is no means for supplying ultrapure water suitable for immersion exposure to factory equipment.

  In addition, since ultrapure water generated by applying a lot of equipment load is discharged as it is after immersion, it is disadvantageous in terms of management cost of factory equipment.

  The present invention has been made in view of the above-mentioned problems, and its intended treatment is to supply standard water such as city water from factory equipment, and to newly provide pure water and ultrapure water generation means. An object of the present invention is to provide an immersion type exposure apparatus that enables immersion exposure with little mixing.

  It is another object of the present invention to provide an immersion type exposure apparatus that can reduce the running cost by providing a means for detecting the purity of the discharged immersion water and collecting it when there is little contamination.

  In order to achieve the above problem, the present invention fills the exposure light passage space between the lowermost surface of the projection optical system and the wafer with ultrapure water, and performs exposure in a state where the exposure light passage space is filled with ultrapure water. The immersion type exposure apparatus includes a pure water generating unit that generates pure water from water.

  According to the present invention, it is possible to provide an immersion type exposure apparatus with little deterioration in image performance by reducing the mixing of ions and particles into ultrapure water which is an immersion liquid used for immersion exposure. In addition, it is possible to provide an environment in which immersion exposure can be performed even in an installation place that does not have ultrapure water supply means. Furthermore, the cost required for the production of ultrapure water can be reduced by providing the wastewater recovery means.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  FIG. 1 is a conceptual diagram of an exposure apparatus according to an embodiment of the present invention, in which parts common to the configuration of the above-described conventional example are denoted by the same reference numerals.

  Water supplied from the factory equipment is supplied to the water tank 2 through the water supply system 1. The water supply system 1 includes a shutoff valve 3 disposed on the supply line 44 and a liquid level sensor 4 disposed in the water tank 2, and the liquid level in the water tank 2 is always within a predetermined range. Open / close control of the shut-off valve 3 is performed so that

  The water in the water tank 2 is sent to the pure water generator 5. In the pure water generating device 5, water is first removed of impurities by the particle removal filter 6 and the activated carbon filter 7, and sent to the reverse osmosis membrane 8. Impurities and ionic components that cannot be removed by the filters are removed from the reverse osmosis membrane 8. Further, residual ions are removed by the ion exchange membrane 9 to generate pure water, which is stored in the pure water tank 12. Here, the generation and supply of pure water is performed in such a way that the liquid level of the pure water tank 12 is always a predetermined level based on the signal of the pure water level sensor 13 disposed in the pure water tank 12 in the pure water generation control system 10. The operation of the pump 11 is controlled so as to be within the range.

  In order to make the generated pure water further ultrapure water, an ultrapure water generator 16 composed of a pure water tank 12, a pure water pump 14, an ion exchange membrane 9 and a return pipe 15 is provided and circulated. To produce ultrapure water. In addition, this circulation system is provided with a degassing membrane 17, which removes dissolved gas in the ultrapure water and suppresses generation of bubbles, which is a cause of defective immersion exposure.

  The ultrapure water generated by the ultrapure water generator 16 is adjusted to a predetermined temperature by the heat exchanger 45 and then sent to the immersion liquid supply / discharge device 41 of the immersion exposure unit. The ultrapure water is filled in the liquid immersion area between the projection lens 36 and the wafer 37 via the supply nozzle 42 of the immersion liquid supply / discharge device 41 and is simultaneously discharged from the discharge port 43.

  The waste water discharged from the discharge port 43 of the immersion liquid supply / discharge device 41 is discharged after measuring the pH value by the pH sensor 18, the specific resistance value by the specific resistance meter 19, and the particle size and amount by the particle counter 20. It is sent to the line switching device 21. The discharge line switching device 21 includes a water recovery line 22 that returns to the water tank 2, a pure water recovery line 23 that returns to the pure water tank 12, a drain line 46 that performs external discharge, and the water recovery line 22 and the pure water recovery. It is composed of a switching valve 24 for switching between the line 23 and the drain line 46, and is based on the output of the discharge line control device 25 that receives the measured pH value, specific resistance value, and particle amount of the drainage. Perform switching control.

  A switching control method of the discharge line control device 25 will be described.

  When the pH value of the wastewater exceeds a predetermined range to become an acidic or alkaline solution, or when the amount of particles exceeds a predetermined amount, the wastewater is discharged to the drain line 46 by the switching valve 24 and discarded to the outside as it is. When the pH value and the amount of particles are within a predetermined range, the following control is followed. If the specific resistance value of the drainage is at the level of pure water, it is collected by the switching valve 24 in the pure water tank via the pure water collection line 23, otherwise it is collected in the water tank 2 via the water collection line 22. Is done.

  According to the present embodiment, since the ultrapure water generating means is built in the exposure apparatus, the ultrapure water supply line can be shortened as much as possible, and mixing of ions and particles can be reduced. Moreover, the production load of ultrapure water can be reduced by detecting the purity of the waste water and providing a switching means for discharging and collecting.

1 is a configuration diagram of an immersion type exposure apparatus according to the present invention. It is a figure which shows the immersion apparatus of the conventional exposure apparatus. It is a figure which shows the conventional exposure apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water supply system 2 Water tank 3 Shut-off valve 4 Liquid level sensor 5 Pure water production | generation apparatus 6 Particle removal filter 7 Activated carbon filter 8 Reverse osmosis membrane 9 Ion exchange membrane 10 Pure water production control system 11 Pump 12 Pure water tank 13 Pure water Liquid level sensor 14 Pure water pump 15 Return pipe 16 Ultrapure water generator 17 Degassing membrane 18 pH sensor 19 Resistivity meter 20 Particle counter 21 Discharge line switching device 22 Water recovery line 23 Pure water recovery line 24 Switching valve 25 Discharge Line control device 31 Light source 32 Introduction unit 33 Illumination optical system 34 Reticle 35 Reticle stage 36 Projection optical system 37 Wafer 38 Wafer stage 41 Immersion liquid supply / discharge device 42 Supply nozzle 43 Discharge port 44 Supply line 45 Heat exchanger 46 Drain line

Claims (10)

  An immersion type exposure apparatus for filling an exposure light passage space between wafers and an exposure light passage space between projection optical systems with ultra pure water and performing exposure in a state where the exposure light passage space is filled with ultra pure water. An immersion type exposure apparatus comprising pure water generating means for generating pure water.   2. The exposure apparatus according to claim 1, wherein the pure water generating means comprises a water tank, a particle removal filter, an activated carbon filter, a pump, a reverse osmosis membrane, and an ion exchange membrane.   An immersion type exposure apparatus that fills the lowermost surface of the projection optical system and an exposure light passage space between wafers with ultrapure water, and performs exposure in a state where the exposure light passage space is filled with ultrapure water. 3. The immersion type exposure apparatus according to claim 1, further comprising ultrapure water generating means for generating ultrapure water from pure water generated by the water generating means.   4. The immersion type exposure according to claim 1, wherein the ultrapure water generating means is a circulation system including a pure water tank, a pump, a UV lamp, an ion exchange membrane, and deaeration. apparatus.   An immersion type exposure apparatus that fills the exposure light passage space between the lowermost surface of the projection optical system and the wafer with ultrapure water, and performs exposure in a state where the exposure light passage space is filled with ultrapure water. 5. The liquid immersion according to claim 1, further comprising: ultrapure water supply / discharge means for supplying and discharging ultrapure water generated by the pure water generation means to and from the exposure light passage space. Mold exposure equipment.   Further, a water recovery line returning to the water tank at a downstream side of the discharge side of the ultrapure water supply / discharge means, a pure water recovery line returning to the pure water tank, a drain line for discharging, the water recovery line and the pure water recovery line 6. An immersion type exposure apparatus according to claim 1, further comprising a discharge line switching means configured by a switching valve for switching the drain line.   Further, a pure water sensor for detecting the purity on the discharge side of the ultrapure water supply / discharge means is provided, and a discharge line control means for controlling the discharge line switching means based on a signal of the pure water sensor is provided. An immersion type exposure apparatus according to any one of claims 1 to 6.   The immersion type exposure apparatus according to claim 1, wherein the pure water sensor can measure at least the pH of the liquid.   8. The immersion type exposure apparatus according to claim 1, wherein the pure water sensor can measure at least liquid particles.   The immersion type exposure apparatus according to claim 1, wherein the pure water sensor can measure at least a specific resistance of the liquid.

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