JPS63241923A - Apparatus for light irradiation - Google Patents

Abstract

PURPOSE:To control the whole wafer surface to a uniform temperature by providing, in addition to the direct irradiation by a plurality of concentrically placed annular light sources, irradiation of the reflected light, and an annular mirror for collecting the light to the outer periphery of a wafer to be treated. CONSTITUTION:In the center of a quartz chamber 2, a wafer 5 as an object to be irradiated is mounted on a supporting stand 6. On the upper surface and lower surface of the chamber 2, a plurality of annular light sources 1a, 1b, 1c are placed around a straight line corresponding to the normal line on the central position of the wafer 5, respectively. A gas supply port 4 is provided in the central upper part of the chamber 2, and an exhaust port 12 is provided in the central lower part thereof. A temperature measuring optical system provided under the center of the chamber guides the radiant energy of a black body from the wafer to a detector 11 by means of objective lenses 7, 8, a two-dimensional scanning mirror 9 and a condensing lens 10 for measuring the temperature distribution of the wafer. Further, reflecting members 20 are placed on the upper and lower surfaces of the chamber 2 for correcting the temperature reduction by heat dissipation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light irradiation device such as a lamp annealing device used in the manufacturing process of semiconductor devices.

[Conventional technology]

2. Description of the Related Art In recent years, technology that utilizes the thermal and chemical effects of light has been adopted in the manufacturing process of semiconductor devices, and the development of light irradiation devices for this purpose has been progressing. This type of light irradiation device has high irradiation energy and
It is necessary to perform uniform heating in order to cause the chemical reaction to proceed uniformly over the entire surface of the wafer, which is the object to be irradiated. As such a light irradiation device, one in which about 10 rod-shaped halogen light sources for heating are arranged each above and below the quartz chamber for the workpiece to be processed in the quartz chamber is used. In such a conventional apparatus, it is necessary to arrange a large number of rod-shaped light sources over a wide area on the upper and lower surfaces of the wafer in order to make the illuminance uniform over the entire surface of the wafer as an object to be processed.

Since the heat dissipation conditions are different between the center and the periphery of the wafer, even if the illumination is uniform, as shown by the broken line in Figure 14,
The temperature at the periphery of the wafer tends to be lower than that at the center, and it has not been easy to heat the wafer substantially uniformly over the entire surface. In calculating the temperature distribution shown by the broken line in Figure 14, a 6-inch silicon wafer is used as the object to be irradiated, light is irradiated with uniform illuminance, and heat is radiated into the still air. This is the result of numerical analysis based on the assumption. As shown in the figure, the temperature rapidly decreases at the outermost periphery of the wafer. In this way, even if uniform light energy is applied to the entire surface of the object to be irradiated, the heat dissipation conditions differ greatly between the center and the outermost periphery of the object to be irradiated, making it impossible to obtain a uniform temperature distribution. Although such a temperature curve on the wafer surface differs depending on the absolute temperature of the wafer, the process that has taken place, the atmosphere inside the chamber, etc., similar data has been obtained with existing lamp annealing equipment, and improvements are needed.

If annealing is performed in a state where temperature uniformity cannot be maintained on the wafer surface, cracks called slip lines will occur, reducing yield.

Furthermore, if there were temperature irregularities even without slip lines, the permissible range of the optimum temperature conditions for annealing would be narrowed, making the device difficult to use.

[Problem that the invention seeks to solve]

For this purpose, for example, there is a device that has an auxiliary heating mechanism around the wafer, as in Japanese Patent Application Laid-open No. 58-194332,
As disclosed in Japanese Unexamined Patent Publication No. 60-247934, a method in which the arrangement density of lamps is changed in order to increase the heating of the wafer peripheral area has been proposed. However, these devices also
In order to obtain uniform illumination conditions, it is necessary to install many rod-shaped light sources to provide a large area light source that far exceeds the area of the wafer, and the heating efficiency is extremely poor, and the rod-shaped lamps are tightly packed on the top and bottom of the chamber. Therefore, it is extremely difficult to control the temperature over the entire surface of the wafer, such as correcting individual differences in the wafer process in the previous process or changing the set temperature, for a wafer to be processed that is originally rotationally symmetrical in shape. Moreover,
Since it does not have a temperature measurement mechanism that covers the entire surface of the irradiated object, it is impossible to set the amount of auxiliary heating under different conditions.Also, since the auxiliary heating mechanism is placed inside the quartz chamber, the configuration becomes complicated, and a gas atmosphere cannot be realized. There were many problems such as the generation of garbage and garbage.

Therefore, the present invention solves the above-mentioned drawbacks, and not only makes it possible to efficiently and uniformly illuminate the entire surface of a wafer as an object to be irradiated, but also makes it possible to easily control the temperature of the outermost part of the wafer. The purpose of the present invention is to provide a light irradiation device that can uniformly heat the entire surface of a wafer.

[Means for solving problems]

The present invention was originally filed in Japanese Patent Application No. 61-2 filed by the same applicant as the present application.
It is based on the light irradiation device disclosed in No. 11208.

That is, in the device disclosed in the previous application, a plurality of annular light sources are arranged concentrically around a predetermined axis corresponding to the center of the object to be irradiated, and the object is illuminated by the annular light sources arranged concentrically. It illuminates and heats a wafer as an irradiation object.

In the present invention, in the configuration of the invention of the earlier application as described above, a reflective member is further arranged behind the annular light sources arranged concentrically, and at least the outermost part of the annular light sources arranged concentrically is provided. The annular light source is configured to provide an illuminance distribution using a concave mirror such that the illuminance is high in the periphery of the irradiated object surface.

Specifically, the annular concave mirror for at least the outermost annular light source is configured such that the light emitting part of the annular light source is located outside the optical axis of the concave mirror and inside the optical axis in a cross section taken on a plane passing through the concentric center. It is something that exists.

[Effect]

In the configuration of the present invention as described above, first, light is irradiated by an annular light source arranged concentrically, so the shape of the light source is rotationally symmetrical with respect to the center of the irradiated object. This enables uniform illumination, and it is possible to uniformly heat and excite chemical reactions over the entire surface of the wafer by light irradiation. Since the reflecting member is disposed behind the concentrically arranged annular light sources, the illumination efficiency can be increased by reflecting the light flux that does not directly reach the surface of the object to be illuminated by the reflecting member. Furthermore, for at least the outermost annular light source among the annular light sources arranged concentrically, a concave mirror is used to provide an illuminance distribution such that the illuminance is high in the periphery of the irradiated object surface. By doing so, it is possible to increase the temperature of the peripheral area where the temperature tends to decrease due to heat radiation of the irradiated object. By independently controlling the amount of light emitted from each annular light source, it becomes possible to heat the irradiated object while maintaining a uniform temperature over the entire surface.

In addition, since the light source has a rotationally symmetrical shape consisting of an annular light source placed concentrically facing the irradiated object, an optical system for observing the irradiated surface can be placed at the center of the annular light source. By arranging the irradiated object on the central axis of the annular light source, it becomes possible to observe or optically inspect the surface of the irradiated object from the central axis of the irradiated object. When using a chamber for irradiating light while placing the irradiated object in a specific gas atmosphere, a supply/exhaust port for supplying and exhausting gas into the chamber can be provided through the center position of the annular light source, Since the gas can be supplied and exhausted from the center of the irradiated object, it is extremely advantageous to maintain the uniformity of the chemical reaction caused by the gas.

In the present invention, the arrangement of the annular light sources is determined so that the light beams directly reaching the irradiated object from the plurality of annular light sources are given uniform illuminance over the entire surface of the irradiated object, while the light beams that do not directly reach the irradiated object are Most of the time, due to the annular mirror installed at the rear, the inner annular light source applies illumination evenly to the irradiated object, and the outer annular light source provides illumination with a specific gravity on the outermost part of the irradiated object. It is desirable that the illumination conditions are such that the light energy applied can maintain and heat the entire surface of the irradiated object at the same temperature.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a schematic sectional view showing the structure of an embodiment of the present invention, and FIG. 2 is a plan view showing the structure of an annular light source used in this embodiment. A wafer 5 as an object to be irradiated is placed on a support table 6 in the center of the quartz chamber 2 . On the upper and lower surfaces of the chamber 2, a plurality of annular light sources 1a, 1b, and 1c are arranged concentrically about a straight line corresponding to the normal N on the center position of the wafer 5, respectively.

The illustrated three annular light sources 1a, lb, and lc are arranged concentrically about a normal line N corresponding to approximately the center of the wafer, as shown in FIG. In each annular light source in FIG. 2, the substantial light emitting part is indicated by a broken line. At the upper center of the chamber 2 is an air supply port 4 for supplying a gas atmosphere.
An exhaust port 12 is provided at the lower center of the chamber, and together with an ejection port 3 for exchanging wafers to be processed, the chamber is configured to maintain a constant pressure in a vacuum or a desired gas atmosphere. A temperature measuring optical system installed at the lower center of the chamber collects blackbody radiation energy from the wafer through an objective lens 7.8, a two-dimensional scanning mirror 9, and a condenser lens 1.
By scanning the entire wafer surface with the two-dimensional scanning mirror 9, the temperature distribution of the wafer can be measured.

The annular lights 11a, lb, and lc arranged concentrically are composed of, for example, halogen lamps, and since the emission spectrum of the halogen lamp is continuous light with a peak at a wavelength of about 1 μm, it passes through a quartz chamber and It is relatively well absorbed by the wafer and has a heating effect. Since the semiconductor wafer 5 as the object to be irradiated has different heat conversion and heat radiation conditions for light energy depending on past processes, lofts, gas atmospheres, etc., in this embodiment, temperature measurement optical systems 7 to 11 capable of two-dimensional scanning are used. The temperature of the entire surface of the irradiated object is constantly measured.
The load of each annular light source is controlled to control the absolute value and uniformity of its temperature.

The temperature of the wafer can also be controlled by using a thermocouple placed near the wafer or by installing a small window for temperature measurement in a part of the chamber, measuring the wafer temperature with a thermal radiation thermometer, and determining the heating conditions using a lamp. It is possible.

When a plurality of annular light sources are arranged concentrically on the upper and lower surfaces of the chamber and the light emission weight of each annular light source is made equal, it is possible to irradiate the entire wafer almost uniformly. The illuminance due to the light beams directly reaching the wafer from the four annular light sources is a value calculated based on the specifications shown in Table 1, and as shown in Table 2, a substantially uniform illuminance distribution is obtained.

1 (1 degree of 4, α - C-relative change in wafer 0.124 However, the heat dissipation conditions are very different between the center and the periphery of the wafer, and as shown by the broken line in Figure 14, the heat dissipation conditions are very different in the wafer center and periphery. In order to compensate for the temperature drop due to heat radiation, the back surface of each annular light source, that is,
A reflecting member 20 is arranged on the opposite side of the chamber 2. The reflecting member 20 is located at -E of the chamber as shown in FIG.
An annular light source having the same configuration is provided behind each of the annular light sources provided on the top and bottom surfaces. Three annular mirrors 21 are arranged concentrically for each annular light source.
a, 21b, and 21C. In this embodiment, the wafer surface is almost uniformly irradiated with the light beam that goes directly toward the wafer from the annular light source, and the light beam that does not directly reach the wafer surface but is guided to the wafer surface by reflection from the reflective member is reflected from the inner annular light source. The light flux reflected from the annular light source illuminates the entire surface of the wafer almost uniformly, and the light flux from the outer annular light source illuminates the periphery of the wafer more intensely. Specifically, among the luminous fluxes from the inner annular light source 1a, the luminous fluxes that do not go directly to the wafer side are almost uniformly irradiated over the entire surface of the wafer by the annular mirror 21a, and the luminous flux from the inner annular light source 1a
Among the light fluxes from the annular light source ICs 21b and 2b, the light fluxes that do not go directly to the wafer surface are directed to the annular mirrors 21b and 2.
1c, the irradiation is concentrated on the periphery of the wafer.

The principle of arrangement of the annular mirror and the annular light source in order to reflect the light flux from the outer annular light source in the above embodiment so that it is more concentrated at the periphery of the wafer will be explained with reference to FIGS. 3 to 6.

3 to G show cross-sectional shapes taken on a plane passing through the concentric centers of the rotationally symmetrical annular light source and the annular mirror. Since both the annular light source and the annular mirror are rotationally symmetrical, it is possible to estimate the actual state of the irradiated light flux by looking at the behavior of the light flux in a cross section passing through the illustrated concentric center.

In the figure, the vertical axis Z represents the optical axis, and T represents the vertex of the annular mirror. The configurations shown in FIGS. 3 and 4 are both cases where the annular mirror is a concave mirror with a spherical cross section.
FIG. 3 shows a case where the light emission center S of the annular light source is located on the axis Z of the annular mirror, and FIG. 4 shows a case where the light emission center S of the annular light source is located off the axis of the annular mirror. 5 and 6 show the case where the annular mirror is a concave mirror with an elliptical cross section, FIG. 5 shows the case where the emission center S of the annular light source is located on the axis of the annular mirror, and FIG. This is a case where the emission center S of the annular light source is located off the axis Z of the annular mirror.

The various quantities for each figure are as shown in Table 3 below.

(K in the ellipsoid represents the conic constant.) In each of the above cases, the light emitting part of the annular light source is regarded as a point light source,
It is assumed that light rays are emitted completely diffusely at equal angles of 5'' from this point light source S within the cross section, and the state of each of these rays is shown as an optical path diagram.When the light source S is placed on the optical axis, , 34.1 ysm from the apex T in Fig. 3, and 34.1 ysm from the apex T in Fig. 5.
As a result, a light source image is formed at the conjugate position of 13.3 cranes, and the entire wafer surface is irradiated almost uniformly. Set the light source S to 31 as shown in Figure 4.
, as shown in FIG. 6, the position where most of the light beam is focused will be shifted off-axis in a direction opposite to the eccentric direction of the light Bs.

From FIG. 4 and FIG. 6, it can be seen that by decentering the light emitting point with respect to the optical axis of the concave mirror, it is possible to concentrate the luminous flux in the peripheral area away from the optical axis of the concave mirror. From the comparison between Figures 3 and 5, it is clear that ellipsoidal mirrors with a conic constant K smaller than 1 can improve light condensation on the axis compared to spherical mirrors. I also understand. As described above, in the present invention, the annular mirror is eccentrically arranged with respect to the outer annular light source as described above, so that the light condensing area is located on the outer periphery of the wafer. This provides an illuminance distribution sufficient to prevent a temperature drop due to heat radiation to the outer peripheral portion of the wafer, making it possible to uniformly heat the entire surface of the wafer.

Figures 7 to 11 show four circular lights [1a, lb.

With a light irradiation device in which lc and ld are arranged with the quantities shown in Table 1 above, and an annular mirror and an annular light source whose cross sections correspond to those shown in FIGS. 4 and 5 of Table 3 are arranged for each annular light source, It is an optical path diagram in a state where a 6 inch (150 cIl+) wafer is irradiated.

In FIG. 7, an annular mirror with a cross-sectional radius of curvature of 131 is arranged for the outermost annular light aid. The annular light source 1d has an outer diameter of about 10φ in cross section, has a resistance wire serving as a light emitting part almost at the center, and is arranged eccentrically inward by y=3 mm with respect to the optical axis Z of the annular mirror cross section. As shown in FIG. 7, the outer periphery of the wafer is illuminated with a poor distribution of illuminance weights.

In addition, in Fig. 8, an annular mirror with a cross-sectional radius of curvature of 13 mm is placed on the inside of the light emitting part S of the light source 1c, which is located one space inside, eccentrically by y = 3 mm. A distribution with a high illuminance weight is given to the outer periphery.

If these annular mirrors are placed behind each annular light source, if the cross section is spherical, it will be impossible to focus the light onto the outer periphery of the wafer unless a relatively large radius of curvature is chosen. The pitch of the annular light source needs to be large due to interference conditions between the light beams of the annular light source and the annular mirror. Therefore, the density of a surface light source formed by a plurality of annular light sources becomes low. Therefore, in order to eliminate this drawback, the action is to make the cross-sectional shape of the outer annular mirror not spherical but elliptical.

9 and 10, for the outer annular light sources 1c and 1d, the radius of apex curvature is lQms in the cross section, and the conic constant =
An annular mirror with an elliptical surface of 0.7 is set. Fig. 9 shows the light rays emitted from the outermost annular light source and reflected by the annular mirror, and Fig. 10 shows the light emitting part S for the second annular light alc from the outside aligned with the optical axis of the annular mirror cross section. On the other hand, since it is set to be eccentric by y=2mn+ on the inside, the outer peripheral portion of the wafer is illuminated with a high illuminance weight.

The radius of curvature of the cross section of the annular mirror is 13 in Figures 7 and 8.
vss, whereas in FIGS. 9 and 10, by making it an ellipse, the apex radius of curvature can be made as small as Ion, so the arrangement of the annular light source can be made small, and a light source portion with high density can be formed. It can be said that a spherical cross section is easier to process but has a lower light source density, whereas an elliptical cross section is more difficult to process and tends to have a higher light source density.

Among the plurality of annular light sources arranged concentrically, in the outer annular light sources, as shown in Figs. However, the inner annular light source is set so that the illuminance of the entire surface of the wafer is nearly uniform as shown in FIG. As shown in FIG. 11, an annular mirror having a concave spherical cross section with a radius of curvature IQwm is arranged for the innermost annular light source 1a so that the light emitting part S of the annular light source 1a is located on the optical axis. It is. In the optical path diagram in Fig. 11, only the left side of the annular light source is shown, but if we also include the right side and assume a space with the normal N as the concentric center as the axis of rotational symmetry, the wafer surface will have a distribution with high illuminance at the center. Make it.

As described above, in the embodiment of the present invention, when the loads of the plurality of annular light sources are assumed to be equal, the structure is as follows.

+11 Four annular lights fila, 1b arranged concentrically
, lc, and ld directly irradiate the wafer, and the entire surface of the wafer is almost uniformly irradiated.

(2) Inner annular light [1a, lb, annular mirror 21
Due to the light beam reaching the wafer after being reflected by a and 21b,
The entire surface of the wafer is irradiated almost uniformly.

(3) Then, the outer annular light [1c, ld] is a luminous flux that reaches the wafer 1 after being reflected by the annular mirrors 21C, 21d, and irradiates the wafer so that the illuminance distribution sharply increases at the outer periphery of the wafer. In particular, it is preferable that the outer annular light source has a diameter larger than the outer diameter of the wafer to be irradiated to increase the illuminance at the outer periphery of the wafer.

According to the above configuration, the temperature distribution on the wafer surface is
As shown by the solid line in Figure 4, it is possible to maintain an extremely uniform temperature, and it is possible to continue heating while maintaining this uniform state. In addition, in the event that the temperature around the wafer should drop, by relatively increasing the power of the outer annular light sources among the plurality of concentrically arranged annular light sources, for example, the 14th annular light source can be instantly As shown by the dashed line in the figure, by controlling the temperature in the peripheral area to be high, it is possible to return to a uniform temperature distribution.

In addition to the above, there are also light fluxes that are not reflected by the annular mirror set and do not reach the wafer directly, and light fluxes that are reflected on the wafer surface and are reflected again by the chamber or the outer walls of the chamber and reach the wafer. Therefore, it is desirable to configure the wafer surface so that the temperature distribution including these light beams is uniform.

As a reflecting member for efficiently directing the light beams from a plurality of concentrically arranged annular light sources toward the wafer surface, it is necessary to arrange each of the annular mirrors as described above in a more or less concentric manner. It is possible to combine mirrors into one piece. A cross-sectional view of the reflecting member 30 having such a configuration is shown in FIG. 12. The reflective member 30 is made of copper or aluminum, which has good heat conductivity, as a base material, and the reflective surface facing the chamber is plated with gold to improve the reflectance of the heating light beam. Further, in order to prevent the reflecting member from becoming high temperature due to receiving the light from the annular light source, a cooling means (not shown) such as air cooling or water cooling is provided. As shown in FIG. 12, for the inner annular light sources 1a and 1b, the cross-sectional shape of the annular mirrors 21a and 21b is a spherical surface with the light emitting part placed on the optical axis, and for the outer annular light sources IC and 1d. The annular mirrors 21C and 21d each have a spherical surface or an aspherical surface such as an ellipse with a light emitting portion placed outside the optical axis.Only the outer reflective surface of each of the outer annular mirrors 21C and 21d is formed into a concave surface.
The inner surface is formed into a flat surface (actually a conical surface) as shown by the straight line in the figure.

In addition, if the heat dissipation of the wafer differs depending on the gas atmosphere and the shape of the chamber, and if it is not so large at the outer periphery, and if it is not necessary to focus the light to the wafer outer periphery, the reflective member 40 may be configured as shown in FIG. It is also possible to do this. As shown in FIG. 13, this reflecting member 40 has a simple structure in which an annular mirror is formed only for the outermost annular light source 1d, and plane mirrors are placed for the other annular light sources. . However, even in this case, the outermost annular light source 1d
In order to make the reflected light have a high intensity at the periphery of the wafer, the light emitting source S can be arranged eccentrically inward by a predetermined amount with respect to the optical axis Z of the concave spherical surface in the cross section. is necessary.

〔Effect of the invention〕

As described above, according to the present invention, in addition to direct irradiation from a plurality of annular light sources arranged concentrically, the irradiation is performed with reflected light from a reflecting member, thereby increasing the illumination efficiency and focusing the light on the outer periphery of the wafer to be processed. By providing an annular mirror that emits light, it is possible to realize a light irradiation device that can control the entire surface of the wafer to a uniform temperature, taking into account heat dissipation from the wafer.

Furthermore, the shape of the chamber, gas atmosphere, wafer process,
Even if the conditions differ depending on the lot, etc., the temperature of the wafer can be appropriately controlled by measuring the temperature of the entire surface of the wafer using the temperature measurement optical system and changing the load on each annular light source.

Incidentally, as the annular light source in the present invention as described above, the second
As shown in the figure, it is difficult to realize a light source in which the light emitting part is continuous over the entire circumference.In practice, it is preferable to form a single annular light source by combining multiple arcuate light sources at desired angles, and It is also possible to combine multiple light sources into an annular shape.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the configuration of an embodiment of the present invention, and FIG.
The figure is a plan view showing the arrangement of the annular light source in the configuration of the embodiment shown in Fig. 1, and Figs. FIGS. 7 and 8 are optical path diagrams of the configuration for searching, and FIGS. Figure 1O is an optical path diagram showing the state of the light ray when the light beam from the outer annular light source is reflected by the concave ellipsoidal annular mirror, and Figure 11 is an optical path diagram showing the state of the light ray when the light beam from the inner annular light source is reflected by the concave ellipsoidal annular mirror. An optical path diagram showing the state of light rays when reflected by a mirror, Figures 12 and 13 are cross-sectional views showing the configuration of a reflecting means integrally constructed with an annular mirror, and Figure 14 shows the temperature on the wafer surface. It is a diagram showing the distribution. [Explanation of symbols of main parts] la, lb, lc, 1cL...Annular light source 20.30.4
0...Reflecting members 21a, 21b, 21c, 21d=-Annular mirror N...
・Concentric center of the annular light source (normal line at the center of the wafer) Applicant: Nippon Kogaku Kogyo Co., Ltd. Representative Patent Attorney Takashi Watanabe I/, 3 Figure □ 3'7.5s@7gs+-*Silicon Urchin 11iL Figure 74 Procedural amendment calculation (method) % formula % 1. Indication of the case Patent application No. 1987-77033 2. Title of the invention...
・. ,′. Light irradiation device □, -Tsuno''3, Relationship with the case of the person making the amendment Patent applicant address 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Name
(411) Nippon Kogaku Kogyo Co., Ltd. Fuku Talents Shike Kuda Representative Director and President Narutada Fukuoka 4, Agent Address ■140 Nippon Kogaku Kogyo Co., Ltd. Ceiling Manufacturing, 1-6-3 Nishi-Oi, Honbunagawa-ku, Tokyo ゎ, Name (78
18) Patent Attorney Takashi Watanabe Telephone (773)
) + 111 (, 0) - 5, date of correction order

Claims (1)

[Scope of Claims] 1) A plurality of annular light sources arranged concentrically around a predetermined axis, and a reflecting member arranged behind the concentrically arranged annular light sources, the reflecting member is configured as an annular concave mirror that provides an illuminance distribution such that the illuminance is high in the periphery of the irradiated object surface for at least the outermost annular light source among the concentrically arranged annular light sources. A light irradiation device, characterized in that an object to be irradiated is illuminated by direct light beams from the plurality of concentrically arranged annular light sources and light reflected by the reflection member. 2) The annular concave mirror for at least the outermost annular light source is configured such that the light emitting part of the annular light source is located outside the optical axis of the concave mirror and inside the optical axis in a cross section in a plane passing through the concentric center. A light irradiation device according to claim 1, characterized in that: 3) For an annular light source located inside of the plurality of annular light sources arranged concentrically, the reflecting member prevents the reflected light from the light emitting part of the inside annular light source from passing onto the surface of the irradiated object. The light irradiation device according to claim 2, characterized in that the light irradiation device is configured to illuminate substantially uniformly.