JPH01913A - lighting equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to illumination devices, and in particular to illumination devices such as mask surfaces, reticle surfaces, etc. on which fine patterns such as electronic circuits are formed on the irradiated surface of semiconductor manufacturing equipment. This invention relates to an illumination device for uniformly illuminating.

(Prior Art) In the manufacturing process of semiconductor manufacturing equipment, patterns provided on a mask are sequentially transferred onto eight surfaces of a sea urchin. In this case, the mask surface is illuminated with an illumination device while held in close contact with or very close to the wafer surface, and the pattern on the mask surface is transferred onto the eight surfaces of the wafer, or the mask is placed conjugately with the wafer surface. (including the reticle) is illuminated and projected onto the wafer surface using a projection lens.

In this case, the image quality of the pattern transferred onto the eight surfaces of the sea urchin is greatly influenced by the performance of the illumination device, such as the uniformity of the illuminance distribution on the illuminated surface. Illumination devices with improved optical performance such as uniform illumination have been proposed, for example, in Japanese Patent Application Laid-Open No. 47-4817 and Japanese Patent Application Laid-Open No. 103976-1982.

Generally, the following requirements are required for lighting devices used in semiconductor manufacturing equipment.

(b) Eliminate uneven illumination on the mask surface.

(0) Improving light collection efficiency.

(8) Setting the angle of incidence of the light beam incident on the mask surface to a desired value.

Conventionally, the removal of uneven illuminance on the mask surface (a) has been achieved by using a multi-beam generating member such as a fly's-eye lens, a self-focusing optical element, or an optical element that focuses ordinary fibers, or a prism arranged radially in many areas. Generates a luminous flux,
This is accomplished by collimating each of these partial luminous fluxes and superimposing them on the irradiated surface (optical inch rate). According to this method, illuminance unevenness can be kept within the range of ±2 to ±3%.

Furthermore, the improvement in light collection efficiency (b) is promoted by increasing the brightness of the light source. The angle of incidence of the incident light beam (c) is set to a desired value depending on the diameter of the multi-beam generating member and the focal length of the collimator lens.

Among these factors, the uniformity of the intensity distribution within the incident light beam is particularly important.

In general, non-uniform intensity distribution already occurs in a light source image formed by a condenser such as an elliptical reflector. For this reason, a method has been proposed in which a plurality of multi-luminous flux generating members are provided following the condenser to improve performance. However, if one multi-luminous flux generating member is disposed in the illumination optical path, a loss of light quantity of 20 to 30% will occur, and therefore, if a plurality of members are used, the light collection efficiency will be greatly reduced.

(Problems to be Solved by the Invention) The present invention provides a semiconductor manufacturing device that improves the uniformity of the light intensity distribution within the light beam, uniformizes the illuminance distribution on the irradiated surface, and improves the light collection efficiency. The purpose is to provide a lighting device suitable for.

(Means for Solving the Problem) A light source, a condensing means for condensing a luminous flux from the light source, a luminous flux mixing means for mixing the luminous flux from the condensing means, and an emission from the luminous flux mixing means. The present invention includes a multi-beam generating means that generates a large number of partial light beams using a light beam, and an irradiation means that irradiates a surface to be irradiated with the light beams from the multi-beam generating means superimposed.

(Embodiment) FIG. 1 is a schematic diagram of an embodiment of the present invention. In the figure, 1 is a light source, such as an ultra-high pressure mercury lamp. Reference numeral 2 denotes condensing means, which is composed of an elliptical mirror or the like, and the light source 1 is arranged near the first focal point of the elliptical mirror 20. Reference numeral 3 denotes a light flux mixing means, which is composed of an optical vibrator having a predetermined shape, and the entrance surface 3a of the optical vibrator 3 is arranged near the second focal point of the elliptical mirror 2. Reference numeral 4 denotes a multi-beam generating means, which includes a condenser lens 5 and an optical integrator 6. The condensing lens 5 is the exit surface 3b of the optical vibe 3
and the entrance surface 6a of the optical integrator 6 are set to have a substantially conjugate relationship.

Further, in this embodiment, the optical constants of the condenser lens 5 are set so that the exit surface 3b forms an enlarged image on the entrance surface 6a. Reference numeral 7 denotes an irradiation means, which is composed of a condenser lens or the like, and uses the light beam from the exit surface 6b of the optical integrator 6 to irradiate the irradiation target surface 8 on which a mask, reticle surface, etc. are set.

The optical integrator 6 is made up of a fly's eye lens made up of a plurality of microlenses, a fiber bundle, etc., and its exit surface 6b forms a secondary light source surface.

In semiconductor manufacturing equipment, etc., masks and reticles are arranged on the irradiated surface 8, and patterns of electronic circuits and the like provided on these are directly transferred onto the wafer surface (not shown), or are projected at a predetermined magnification using a projection lens. It is projected and transcribed.

In this embodiment, the light beam mixing means 3 refers to an optical element that has one clear optical axis and one area, such as the aforementioned light pipe, and has one specific light beam. Moreover, the multi-beam generating means 4 has a plurality of optical axes like a fly's eye lens or a fiber bundle, and has a region of a finite area centered on each optical axis, and each region has a plurality of optical axes. An optical element that allows a single beam of light to be specified.

In this embodiment, the light beam from the light source 1 is condensed by the elliptical mirror 2, and the incident surface 3 is placed near the second focal point of the elliptical mirror 2.
The light is incident on the optical pipe 3 arranged so that the point a is located. The optical pipe 3 has a cylindrical shape, for example, as shown in FIG.
The light is emitted from the emission surface 3b. At this time, the number of reflections of the light beam incident on the incident surface 3a of the optical pipe 3 on the inner wall surface depends on the magnitude of the incident angle, and increases as the incident angle increases.

As a result, the light beams are mixed in the optical pipe 3, and for example, a non-uniform intensity distribution on the entrance surface 3a as shown in FIG. 3(A) is changed to a uniform intensity distribution on the exit surface 3b as shown in FIG. 3(B). The intensity distribution is as follows. That is, the intensity distribution is smoothed.

Then, as shown in FIG. 1, the light beam emitted from the exit surface 3b of the optical pipe 3 is condensed by the condenser lens 5,
The light is focused on the incident surface 6a of the optical integrator 6. By using the condensing lens 5 in this manner, the exit surface 3b and the entrance surface 6a are brought into optical contact with each other to improve the light collection efficiency, and the exit surface 3b is placed on the entrance surface 6a.
A uniform intensity distribution similar to that in b is formed.

The intensity distribution on the entrance surface 6a of the optical integrator 6 is directly transferred to the exit surface 6b, so the intensity distribution on the exit surface 6b, which becomes the secondary light source surface, becomes a uniform intensity distribution as shown in FIG. 3(B). ing.

The optical integrator 6, for example, as shown in FIG. 4, divides the target effective light beam into a plurality of minute areas 4-1, 4-2, etc. using a fiber bundle or the like. −． It is divided into 4-n. The filling rate of each area at this time is about 70 to 80%. By superimposing and irradiating the surface to be irradiated 8 with the light beams emitted from each minute area by the condenser lens 7, the illuminance distribution on the surface to be irradiated 8 is uniform as a whole. At this time, the optical constants of the optical integrator 6 and the condenser lens 7 are set so that the entrance surface 6a of the optical integrator 6 and the irradiated surface 8 have a substantially conjugate relationship.

Further, in this embodiment, the optical constants of the condenser lens 5 are set so that the exit surface 3b of the optical pipe 3 forms an enlarged image on the entrance surface 6all of the optical integrator 6, so that the light flux from the exit surface 3b is The light is made to enter the incident surface 6a efficiently.

In this embodiment, the condenser lens 5 may not be used, and the optical pipe 3 and the optical integrator 6 may be directly joined.

In this embodiment, an optical pipe is used to mix all of the incident light beams, thereby reducing optical loss and making it easier to make the intensity distribution within the light beam uniform. That is, it facilitates making the intensity distribution of the secondary light source surface uniform.

Furthermore, by controlling the shape and length of the optical pipe and the reflectance of the inner wall surface, it is possible to arbitrarily control the intensity distribution within the light beam.

FIGS. 5(^), (B), and (C) are schematic diagrams of other embodiments of the optical pipe according to the present invention.

The optical pipe 51 shown in FIG. 5A is made of a glass cylinder, and the incident light beam is repeatedly totally reflected on the side surface and exits from the exit surface 51b. In this embodiment, a reflective film may be applied to the side surface.

Figures (B) and ((:) indicate that the sides are inclined, and the optical pipe 52 in Figure (B) reduces the diameter of the incident light beam and emits it from the exit surface 52b. On the contrary, the optical pipe 53 of C) enlarges the diameter of the incident light beam and emits it from the exit surface 53b.

In this way, by changing the angle of the side surface of the optical pipe, the diameter and exit angle of the light beam from the exit surface can be changed arbitrarily. That is, since the exit angle and exit beam diameter of the light beam from the exit surface are constant values due to Helmholtz-Lagrange invariants, this is utilized to appropriately set the exit angle and exit beam diameter.

FIGS. 6 and 7 are schematic diagrams of other embodiments showing the relationship between the luminous flux mixing means and the multi-luminous flux generating means in the illumination device of the present invention.

In the embodiment shown in FIG. 6, field lenses 62 and 63 are arranged on both sides of the optical pipe 3, and the incident angle of the incident light beam and the exit angle of the emitted light beam are corrected, and the light beams are mixed more efficiently. The intensity distribution is made uniform.

In this embodiment, even if the field lens is placed only on one side of the optical pipe 3, the desired effect can be obtained.

The embodiment shown in FIG.
The light beam from the optical integrator 6 is made into a substantially parallel light beam by a condenser lens 71 and is made to enter the entrance surface 6a of the optical integrator 6.

This transfers the orientation distribution of the exit surface 3b to the entrance surface 6a. Even if the exit surface 3b and the entrance surface 6a are not necessarily in a conjugate relationship by the condenser lens 71 as in the embodiment shown in FIG. The uniformity of the intensity distribution can be achieved satisfactorily.

In addition, in the embodiments shown in FIGS. 1 and 7, field lenses as shown in FIG. 6 may be placed on both sides or one side of the optical pipe, thereby further improving the light collection efficiency. be able to.

(Effects of the Invention) According to the present invention, by using the light flux mixing means and multi-light flux generation means having the above-described configurations, it is possible to achieve high light collection efficiency, and to even out the intensity distribution of the secondary light source surface and It is possible to achieve an illumination device that is particularly suitable for semiconductor manufacturing equipment, in which the illuminance distribution on the irradiation surface can be easily made uniform.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of an embodiment of the optical pipe according to the present invention, and FIG.
A) and (B) are explanatory diagrams of the intensity distribution of the entrance surface and exit surface of the optical pipe shown in FIG. 2, FIG. 4 is an explanatory diagram of an embodiment of the optical integrator according to the present invention, and FIG. ), (B), ((:) is an explanatory diagram of another embodiment of the optical pipe according to the present invention, 6th.
FIG. 7 is a schematic diagram of the main parts of another embodiment of the present invention. In the figure, 1 is a light source, 2 is a condensing means, 3 is a light flux mixing means, 4
5 is a condenser lens, 6 is an optical integrator, 7 is an irradiation means, and 8 is an irradiated surface. Figure 2 Figure 3 (A) (B) Drunkenness 4 Figure 5 (A) (B) (Figure 6)

Claims (5)

[Claims] (1) a light source, a condensing means for condensing the luminous flux from the light source, and a luminous flux mixing means for mixing the luminous flux from the condensing means;
A multi-beam generating means that generates a large number of partial light beams using the light beam emitted from the light beam mixing means, and an irradiation means that irradiates a surface to be irradiated with the light beams from the multi-beam generating means superimposed. A lighting device characterized by: (2) The lighting device according to claim 1, wherein the light beam mixing means has an optical pipe. (3) The multi-beam generating means has a condenser lens and an optical integrator, and the exit surface of the light beam mixing means and the entrance surface of the optical integrator are maintained in a substantially conjugate relationship through the condenser lens. The lighting device according to claim 2, characterized in that: (4) The lighting device according to claim 3, wherein each element is set so that the exit surface of the optical integrator becomes a secondary light source surface. (5) The illumination device according to claim 3, wherein the condenser lens is set so that the exit surface of the light beam mixing means is enlarged and imaged onto the entrance surface of the optical integrator.