TW201506549A - Light source device and exposure device - Google Patents

Abstract

Disclosed is a light source device of an exposure device capable of saving space, featuring small optic loss in combining light beam with a light beam combination element, no necessity for upsizing the light beam combination element, and capable of substituting for a light tube based light source of a conventional exposure device. The light source device comprises: first, second, and third array light sources that are formed by arranging a plurality of light source elements having first, second, and third wavelength characteristics; first, second, and third lens arrays that are formed by arranging collimation lenses corresponding to the light source elements of the first, second, and third array light sources; a first light beam combination element that combines parallel light having the first wavelength characteristic formed by the first lens array and parallel light having the second wavelength characteristic formed by the second lens array to form a first combined light beam; a second light beam combination element that combines the first combined light beam of first light beam combination element and parallel light having the third wavelength characteristic formed by the third lens array to form a second combined light beam; and a condenser lens that condenses the second combined light beam of the second light beam combination element on a light quantity homogenization element.

Description

Light source device and exposure device

The present invention relates to a light source device for an exposure device, and particularly to a light source device and an exposure device using a plurality of array light sources having different wavelength characteristics.

In the past, a light tube was used in the light source of the exposure device. Specifically, for example, in the wiring pattern formation of the printed substrate or the formation of the solder resist film, depending on the sensitivity characteristics of the photosensitive material to be used, a strong emission of 436 nm (g line), 405 nm (h line), and 365 nm (i line) is used. The mercury lamp of the spectral line is in the light source. In response to this, in recent years, in response to the demand for long life of the light source or power saving, the light source device using the LED instead of the mercury lamp in the light source has been continuously developed. LED has the advantage of longer life than mercury lamp, but on the other hand, one LED outputs less light than a mercury lamp, and outputs a wide-band light including a g-line, an h-line, and an i-line with respect to a mercury lamp, LED Light of a wavelength of a specific narrow band is output, and thus cannot be directly used in a light source for an exposure device requiring a wide band.

Therefore, a scheme of obtaining a light amount corresponding to a mercury lamp tube using an LED array light source composed of a plurality of LEDs, and using a plurality of LED array light sources having different wavelength characteristics to obtain a plurality of wavelengths of light in accordance with sensitivity characteristics of the photosensitive material is proposed. . In Patent Document 1, an image of a light-emitting portion in which each LED element is formed is superimposed on a plurality of LED array light sources having different wavelength characteristics. In the lens array, the collected light beams of the same lens array are superimposed on the dichroic mirror to form a composite image of the light-emitting portion image, and are imaged on the incident surface of the integrator (light quantity uniformizing element).

The projection exposure apparatus (stepper) of Patent Document 2 uses a light source device that synthesizes light emitted from a plurality of LED array light sources having different wavelength characteristics using a dichroic mirror and images the incident surface of the integrator. In Patent Document 2, light emitted from each LED element of the LED array light source is incident on the dichroic mirror as divergent light.

[Advanced technical literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-63390

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-335949

The dichroic mirror generally shifts in accordance with the angle of incidence of the light, and the cutoff wavelength of the reflection and transmission of the light is shifted. When the wavelength difference between the transmitted light and the reflected light is small, the utilization efficiency of light is lowered due to the translation of the cutoff wavelength. In Patent Document 1, an image of an LED array is imaged at an entrance of an integrator, and light at a peripheral portion of the LED array is blocked at an integrator entrance to cause a loss of light amount. Further, in Patent Document 1, when the conjugate surface of the LED array is provided in the optical system in the optical path, optical elements such as lenses are increased, and as a result, a lot of space is required for arranging the light source device.

In Patent Document 2, the area of the dichroic mirror increases as the light emitted from the light source expands, and the light source device must have a lot of space. Further, in Patent Document 1 and Patent Document 2, incidence from each of the LED array light sources to the first condensing lens Since the optical path lengths at the positions must be equal, the more the number of combined LED arrays increases, the longer the optical path length tends to be, and thus more space is required. Therefore, in these optical systems, there is a problem that the size of the lamp light source of the conventional exposure apparatus is larger and it is impossible to exchange with the light source of the conventional exposure apparatus.

An object of the present invention is to provide a light source device for a space-saving exposure apparatus, which can reduce light loss of a dichroic mirror (beam combining element) at the time of beam combining, does not require an enlargement of a dichroic mirror, and can replace an existing exposure apparatus. Lamp source.

The present invention is accomplished by converting a light beam of a plurality of LED array light sources (array light sources) emitting light of different wavelengths into a parallel light beam and then incident on a dichroic mirror (beam combining element), thereby achieving low light loss and no need for long A small light source device with a long optical path.

A light source device according to the present invention includes: a first array light source in which a plurality of light source elements that emit light of a first wavelength characteristic are arranged; and a first lens array that corresponds to each light source element and has the first wavelength characteristic The second array light source is formed by arranging a plurality of light source elements that emit light of a second wavelength characteristic different from the first wavelength characteristic; and the second lens array; a third collimating lens that reflects each of the light source elements and converts the light of the second wavelength characteristic into parallel light; and the third array light source emits a third wavelength different from the first and second wavelength characteristics a plurality of light source elements of characteristic light are arranged; the third lens array is formed by arranging collimating lenses corresponding to the respective light source elements and converting the light of the third wavelength characteristic into parallel light; the first optical composite element Synthesizing the first wavelength ray formed by the first lens array by sharing a main optical axis The parallel light of the second parallel light and the second wavelength characteristic formed by the second lens array are the first combined light beams, and the second optical composite element combines the first combined light beam and the first optical common axis. The parallel light of the third wavelength characteristic formed by the lens array forms a second combined beam, and a collecting lens that collects the second optical combining element and then enters the light amount uniformizing element.

The first optical combining element and the second optical combining element are actually constituted by the first and second dichroic mirrors, respectively. At least one of the first and second dichroic mirrors is arranged such that an incident angle of a light beam incident on the dichroic mirror from the first to third array light sources is less than 45°.

More specifically, the first dichroic mirror may be arranged such that the incident angle of the light beam incident from the first array light source is 45°, and the second dichroic mirror is arranged such that the incident angle of the light beam incident from the third array light source is less than 45 °.

One of the wavelength characteristics of the first array light source and the second array light source is the longest wavelength, and the other is the shortest wavelength, and the wavelength characteristic of the third array light source is preferably the intermediate wavelength between the longest wavelength and the shortest wavelength.

The energy distribution of the light beam incident on the incident surface of the light amount equalizing element is a continuous change with a low peripheral portion of the center portion.

It is preferable that most of the light source elements of the array light source are arranged in a lattice shape or a staggered shape.

Another aspect of the invention is an exposure apparatus using the above light source device.

In the light source device of the present invention, since the light emitted from the LED array light source (array light source) is incident on the dichroic mirror (beam combining element) in a state of parallel light, It is possible to suppress the loss of the incident angle due to the difference in the incident position, and to realize an efficient light source device. Further, since the beam combining is performed in the state of the parallel light, the dichroic mirror does not become large, and the optical path of the parallel light portion can be made free length. Therefore, even in the optical system in which three or more array light sources are combined, A light source device capable of realizing space saving.

10‧‧‧Exposure device

11‧‧‧Light source device

12‧‧‧Power supply unit

13‧‧‧Lighting optical system

13a‧‧‧column integrator

13b‧‧‧Injected end face

14‧‧‧ Drawing means

15‧‧‧Exposure table

16‧‧‧Control device

21‧‧‧1st LED array light source

22‧‧‧2nd LED array light source

23‧‧‧3rd LED array light source

24‧‧‧4th LED array light source

21a, 22a, 23a, 24a‧‧‧ LED components

21X, 22X, 23X, 24X‧‧‧ main optical axis

31, 32, 33, 34‧‧‧ lens array

31a, 32a, 33a, 34a‧‧ ‧ collimating lens

41‧‧‧1st dichroic mirror

42‧‧‧2nd dichroic mirror

43‧‧‧ Concentrating lens

44‧‧‧3rd dichroic mirror

W‧‧‧Substrate

Fig. 1 is a block diagram showing the overall architecture of an exposure apparatus including a light source device of the present invention.

Fig. 2 is a view showing an optical architecture of a first embodiment of the light source device of the present invention.

Fig. 3 is a view showing an optical architecture of a second embodiment of the light source device of the present invention.

Figure 4 is a plan view showing an embodiment of an LED array light source.

Figure 5 is a plan view showing another embodiment of an LED array light source.

Fig. 6 is a view showing the light amount distribution of light of the incident end face of the rod integrator of the incident illumination optical system.

Fig. 7 shows the characteristics of the incident angle and the transmittance (reflectance) with respect to the dichroic mirror.

Fig. 8 shows the characteristics of other incident angles and transmittance (reflectance) with respect to the dichroic mirror.

Fig. 1 shows the entirety of an exposure apparatus 10 including a light source device 11 which is the object of the present invention. In Figure 1, the arrows indicate light and the lines indicate control letters. The connection of the number. The light emitted from the light source device 11 driven by the power supply device 12 is incident on the illumination optical system 13, and the light emitted from the illumination optical system 13 is incident on the pattern drawing means 14. The pattern drawing means 14 irradiates light incident from the illumination optical system 13 to the substrate W placed on the exposure table 15. The substrate W is coated or deposited with a photosensitive material. The power supply device 12, the pattern drawing means 14, and the exposure table 15 are controlled by the control device 16.

More specifically, the illumination optical system 13 includes an integrator (light amount uniformizing element) that uniformizes the surface light amount distribution of the light emitted from the optical device 11 such as a rod integrator, and forms a shape suitable for the pattern drawing means 14. Lighting light. The pattern drawing means 14 converts the illumination light incident from the illumination optical system 13 into pattern light for forming a pattern on the photosensitive material on the substrate W. The illumination optical system 13 can be provided with a shutter, a light amount adjustment means, and the like.

In the pattern drawing means 14, for example, a light modulation element such as DMD or the like, or a light shielding means such as a photomask can be used. In addition, a projection optical system for projecting the pattern light to the photosensitive material can be further provided. The photosensitive material can approach or be a light-shielding means for abutting a photomask or the like. The pattern drawing means 14 and the optical system accompanying the pattern drawing means 14 are appropriately designed in accordance with the use of the exposure apparatus 10. The exposure table 15 can also serve as a substrate alignment means, a substrate transfer means, and the like as needed. The shape of the exposure table 15 and the like are appropriately designed in accordance with the substrate.

The present invention is applicable to, for example, the light source device 11 in the exposure device 10 of the above-described configuration, and Fig. 2 shows the first embodiment thereof.

The light source device 11 of this embodiment has a first LED array light source 21 that emits light having a first wavelength characteristic (365 nm), and a second LED array light source 22 that emits light having a second wavelength characteristic (405 nm), and emits a third wavelength characteristic. The third LED array light source 23 of light (385 nm). Light source device 11 will not these Light of the same wavelength characteristic is synthesized sequentially from the upstream. The first to third LED array light sources 21, 22, and 23 have the same structure except for the emitted wavelengths, and each of them has a plurality of LED elements 21a that emit light of 365 nm, a plurality of LED elements 22a that emit light of 405 nm, and emits 385 nm. A plurality of LED elements 23a of light. In the second drawing, only three LED elements 21a, 22a, and 23a are arranged for the sake of simplicity of the drawings. Actually, these LED elements 21a, 22a, and 23a are arranged in a plurality of planes in the vertical direction and the lateral direction. 4 and 5 show an example of a specific planar arrangement. In the example of Fig. 4, the LED elements 21a, 22a, and 23a are vertically and horizontally arranged in a lattice shape (matrix shape), and in the example of Fig. 5, the vertical and horizontal directions are Arranged in a staggered shape. The staggered arrangement is such that when the arrangement pitch of the LED elements 21a, 22a, 23a of the respective rows is p, the pitch of the upper and lower LED elements 21a, 22a, 21c is shifted by p/2. This staggered arrangement is arranged in a lattice shape, and the density of the LED elements can be increased to suppress the loss of light used in the illumination optical system.

The lens arrays 31, 32, and 33 are superposed on the first to third LED array light sources 21, 22, and 23, respectively. Each of the lens arrays 31, 32, and 33 includes a plurality of collimator lenses 31a, 32a, and 33a, and converts the divergent lights of the respective LED elements 21a, 22a, and 23a into parallel beams in accordance with the respective LED elements 21a, 22a, and 23a. Although the LED element strictly performs surface light emission, since the light-emitting area is relatively small with respect to the optical system, it can be said that it is a point light source. Therefore, the light emitted from the LED element can be converted into a parallel light beam using a collimator lens. The parallel beams described herein do not necessarily have to be completely parallel, and may have an included angle (e.g., within 2°) with respect to the optical axis as long as they are substantially visible as parallel light. The planar arrangement of the collimator lenses 31a, 32a, and 33a is the same as the planar arrangement of the LED elements 21a, 22a, and 23a, and the fourth and fifth figures are combined and drawn. As known in the art, relative to LED components The light of the light-emitting portions of 21a, 22a, and 23a is divergent light, and the collimator lenses 31a, 32a, and 33a convert the divergent light into a parallel light beam in units of the respective LED elements 21a, 22a, and 23a. That is, the optical axes of the LED elements 21a, 22a, 23a which are converted into parallel beams by the respective collimator lenses 31a, 32a, 33a are parallel to each other and independent of each other, and have no mutual relationship. Hereinafter, for convenience of explanation, the optical axis of the center of the parallel beam group formed by the first LED light source 21, the lens array 31, the second LED light source 22, the lens array 32, the third LED light source 23, and the lens array 33 is defined as the main light. Axis 21X, 22X, 23X.

The first dichroic mirror 41, the second dichroic mirror 42, and the collecting lens 43 are disposed on the main optical axis 21X of the first LED array light source 21 in this order. The column integrator 13a of the illumination optical system 13 is located at the light collecting position of the collecting lens 43. The incident angle with respect to the main optical axis 21X of the first dichroic mirror 41 (the angle between the main optical axis 21X and the normal to the incident surface of the mirror 41) is α, with respect to the main optical axis 21X of the second dichroic mirror 42. The incident angle (the angle between the main optical axis 21X and the normal to the incident surface of the mirror 42) is β.

The second LED array light source 22 is disposed such that the main optical axis 22X reflected by the back surface of the first dichroic mirror 41 and reflected rearward matches the main optical axis 21X. The third LED array light source 23 is disposed such that the main optical axis 23X reflected rearward of the second dichroic mirror 42 and the main optical axis 21X (and the main optical axis 22X) coincide with each other. The incident angle with respect to the main optical axis 22X of the first dichroic mirror 41 (the angle between the main optical axis 22X and the normal line of the rear surface incident surface of the mirror surface 41) is γ, and in this embodiment, α = γ = 45°. . The incident angle with respect to the main optical axis 23X of the second dichroic mirror 42 (the angle between the main optical axis 23X and the normal to the back surface incident surface of the mirror 42) is δ, and in this embodiment, β = δ = 25°. (β = δ < 45 °).

The first dichroic mirror 41 has a characteristic of transmitting light having a wavelength characteristic of the first LED array light source 21 and reflecting light having a wavelength characteristic of the second LED array light source 22. Sex. The second dichroic mirror 42 has a characteristic of transmitting light having a wavelength characteristic of the first LED array light source 21 and the second LED array light source 22 and reflecting light of a wavelength characteristic of the third LED array light source 23 .

In other words, the first dichroic mirror 41 and the second dichroic mirror 42 are designed and manufactured as a multilayer film in order to obtain the above-described transmission and reflection characteristics while considering the angles α, β, γ, and δ.

Therefore, the first dichroic mirror 41 and the second dichroic mirror 42 combine parallel beam groups from the first LED array 21 and the lens array 31, the second LED array 22 and the lens array 32, the third LED array 23, and the lens array 33. The synthesized light is transmitted through the collecting lens 43 to the incident end surface 13b of the rod integrator 13a of the illumination optical system 13. The rod integrator 13a is a generally known light quantity uniformizing element that homogenizes the plane light quantity distribution of the incident light beam.

In the present embodiment, the light beam of the first LED array light source 21 and the light flux of the second LED array light source 22 incident on the first dichroic mirror 41, the light beam of the first LED array light source 21 incident on the second dichroic mirror 42, and the second LED Any of the light beams of the array light source 22 and the light beams of the third LED array light source 23 are parallel light beams (groups). Therefore, the incident angle at which light is incident on any one of the first dichroic mirror 41 and the second dichroic mirror 42 is the same (the incident angle is not different depending on the incident portion of the light), and is transmitted through the beam splitter or The proportion of light reflected by the beam splitter is the same. Therefore, the light loss at the dichroic mirror can be minimized by appropriately designing the reflection of the dichroic mirror and the cutoff wavelength of the transmission.

In the present embodiment, the first dichroic mirror 41 on the upstream side synthesizes the light emitted from the first LED array light source 21 of the shortest wavelength (365 nm) and the light emitted from the second LED array light source 22 of the longest wavelength (405 nm), and then flows downward. Side The second dichroic mirror 42 synthesizes light emitted from the third LED array light source 23 having an intermediate wavelength (385 nm). There is a great difference in wavelength between the wavelength emitted by the first LED array light source 21 and the wavelength emitted by the second LED array source 22, so that the first dichroic mirror 41 can take a larger tolerance for switching the cutoff wavelength of transmission and reflection. . Therefore, the incident angles α and γ incident on the first dichroic mirror 41 are set to 45° which is excellent in the arrangement efficiency which can minimize the mirror surface area. On the other hand, the wavelength difference between the transmission wavelength of the second dichroic mirror 42 and the reflection wavelength is small. Therefore, when the incident angle δ is 45°, part of the light incident on the second dichroic mirror 42 by the third LED array light source 23 is transmitted without being reflected, and the efficiency is not good. Therefore, in the embodiment of Fig. 2, the incident angle δ toward the main optical axis 23X of the second dichroic mirror 42 is set to 25°, and the width of the cutoff wavelength for switching transmission and reflection is narrowed (the cutoff wavelength curve is made). The tilt becomes impatient). In this way, the angle of the dichroic mirror is appropriately set in accordance with the interval of the wavelength of the combined light, thereby improving the light use efficiency of the light source device.

Fig. 7 and Fig. 8 are diagrams showing the incident angle θ of the incident dichroic mirror, the incident wavelength nm, and the wavelength (transmittance) for switching transmission and reflection. The dichroic mirror has a cutoff wavelength of about 20 nm as shown in Fig. 7 under the use of 45°. on the other hand. At a use of 25°, the cutoff wavelength has a width of about 10 nm (Fig. 8). Therefore, as shown in Fig. 8, when the interval of the wavelength of the synthesized light is narrow, it is desirable to reduce the angle of the dichroic mirror to be used in a state where the width of the cutoff wavelength is narrow. If the light incident on the dichroic mirror is non-parallel and the incident angle will vary depending on the position, as shown in Fig. 7, the position of the cutoff wavelength will shift. Therefore, as a whole of the dichroic mirror, the result is the same as the width of the cutoff wavelength. For example, when the incident angle has a difference of 9°, the width of the cutoff wavelength is substantially expanded by about 10 nm to become 30 nm (Fig. 7).

Further, in the present embodiment, the lens arrays 31, 32, 33 of the first to third LED array light sources 21, 22, and 23 are parallel to the condensing lens 43, and the first to third LED array light sources 21, The conjugate plane of 22, 23 does not exist. Therefore, the optical path length between the first to third LED array light sources 21, 22, 23 to the collecting lens 43 can be any distance. That is, the optical path lengths of the first LED array light source 21 to the condensing lens 43, the second LED array light source 22 to the condensing lens 43, and the third LED array source 23 to the condensing lens 43 are not limited, so the optical path design The high degree of freedom allows for space savings in the light source unit.

Fig. 6 shows the light amount distribution of the light beam incident on the incident end surface 13b of the rod integrator 13a of the illumination optical system 13. In the present embodiment, the relationship between the LED elements and the incident end surface 13b of the rod integrator is Kohler illumination. The light collected by the collecting lens 43 on the incident end surface 13b of the rod integrator 13a is parallel light from all the LED elements, and therefore the light amount distribution on the incident end surface 13b of the rod integrator 13a is the center having the highest energy density. The continuous pattern having a lower energy density toward the periphery has a Gaussian distribution with a low peripheral portion at the center portion. Therefore, even if the incident opening size of the rod integrator 13a is small, the illumination optical system 13 can extract a large amount of light, and the utilization efficiency of light can be improved.

Fig. 3 is a view showing an embodiment of a four-wavelength synthesis. In the light source device 11 of Fig. 2, a third dichroic mirror 44 is disposed on the main optical axis 23X of the third LED array light source 23, and The parallel beam group of the fourth LED array light source 24 and the lens array 34 of the intermediate wavelength (400 nm) light is incident on the back surface incident surface of the third dichroic mirror 44. The fourth LED array light source 24 includes a plurality of LED elements 24a that emit light of 400 nm (see FIGS. 4 and 5). The lens array 34 includes a plurality of collimator lenses 34a, and the LED elements 24a are emitted corresponding to the LED elements 24a. The astigmatism turns into a parallel beam. The third dichroic mirror 44 has a characteristic of transmitting light of 385 nm emitted from the third LED array light source 23 and reflecting light of 400 nm emitted from the fourth LED array light source 24. The incident angle of the main optical axis 23X with respect to the third dichroic mirror 44 (the angle between the main optical axis 23X and the normal of the incident surface of the mirror surface 43) is ε, and the incident angle of the main optical axis 24X with respect to the third dichroic mirror 44 (main The angle between the optical axis 24X and the normal line of the back surface incident surface of the mirror surface 44 is η.

In the above embodiment, it is shown that the LED array light sources 21 to 24 represent array light sources, but a semiconductor laser array light source or an optical fiber array light source that bundles the semiconductor laser elements with the optical fiber connectors may be used. Further, although the beam combining elements are shown as an example of the dichroic mirrors 41 to 43, a beam combining element such as a color separation pupil may be used.

11‧‧‧Light source device

13‧‧‧Lighting optical system

13a‧‧‧column integrator

13b‧‧‧Injected end face

21‧‧‧1st LED array light source

22‧‧‧2nd LED array light source

23‧‧‧3rd LED array light source

21a, 22a, 23a‧‧‧ LED components

21X, 22X, 23X‧‧‧ main optical axis

31, 32, 33‧‧‧ lens array

31a, 32a, 33a‧‧ ‧ collimating lens

41‧‧‧1st dichroic mirror

42‧‧‧2nd dichroic mirror

43‧‧‧ Concentrating lens

Claims (5)

A light source device comprising: a first array light source in which a plurality of light source elements emitting light of a first wavelength characteristic are arranged; and a first lens array respectively corresponding to each light source element and having light of the first wavelength characteristic a collimating lens that is converted into parallel light is arranged; the second array light source is formed by a plurality of light source elements that emit light of a second wavelength characteristic different from the first wavelength characteristic; and the second lens array is paired Each of the light source elements is formed by arranging a collimating lens that converts the light of the second wavelength characteristic into parallel light, and the third array light source emits a third wavelength characteristic different from the first and second wavelength characteristics. a plurality of light source elements of light are arranged; the third lens array is formed by arranging collimating lenses corresponding to the respective light source elements and converting the light of the third wavelength characteristic into parallel light; the first optical combining element The parallel light of the first wavelength characteristic formed by the first lens array and the parallel light of the second wavelength characteristic formed by the second lens array are combined to form a first combined beam and a second optical Synthetic component, The first combined beam and the parallel light of the third wavelength characteristic formed by the third lens array are combined to form a second combined beam, and a collecting lens is formed to share the main optical axis, and the second optical combining element is assembled The light is incident on the light amount uniformizing element. The light source device according to claim 1, wherein the first optical combining element and the second optical combining element are a first dichroic mirror and a second color separation, respectively The mirror is configured such that at least one of the first dichroic mirror and the second dichroic mirror is disposed such that an incident angle of a light beam incident on the dichroic mirror from the first to third array light sources is less than 45°. The light source device according to claim 2, wherein the first dichroic mirror is disposed such that an incident angle of a light beam incident from the first array light source is 45°, and the second dichroic mirror is disposed from the third The incident angle of the beam incident by the array source is less than 45°. The light source device according to any one of claims 1 to 3, wherein one of the wavelength characteristics of the first array light source and the second array light source is the longest wavelength, and the other is the shortest wavelength, the third The wavelength characteristic of the array source is the intermediate wavelength between the longest wavelength and the shortest wavelength. An exposure apparatus comprising: the light source device according to any one of claims 1 to 4 of the patent application.