JPS6162017A - Controlling method of illumination distribution - Google Patents

Abstract

PURPOSE:To obtain uniform illumination distribution in accordance with a distance between a lens and a substance to be irradiated even if the distance is restricted by designing the lens for a shape corresponding to an irradiation distance by pending. CONSTITUTION:Light from a lamp 3 is reflected by a condenser 4, condensed on a lens 1, transmitted through a lens 2, and irradiated to a wafer as parallel light. The lens 2 shown in Fig. (d) is a lens having convex surfaces on both the sides and forms ununiform distribution increasing illumination on its center part and reducing it on its peripheral part at a position of a distance L1 and its uniform distribution is obtained at a far position. When the lens 2 is replaced by a meniscus lens shown in the Fig. (b), (f), uniform illumination distribution can be obtained and the lens 2 can be designed for the shape. Consequently, the illumination distribution on the exposed surface can be restricted within + or -2.5% only by said lens system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an illuminance distribution control method.

Light emitted from lamps is widely used in various industrial fields, one of which is the semiconductor manufacturing process. Light is also extensively used in this semiconductor manufacturing process, but for example, in semiconductor manufacturing equipment such as aligners and steppers, the wavelength is 365.405, 4360.
The wafer is exposed to light from an ultra-high-pressure mercury lamp such as a mercury lamp, but the illuminance distribution on the exposed surface must be made as uniform as possible. In particular, these days wafers are 5 inches,
The uniformity of the illuminance distribution is within ±3π for the 6-inch large area L1 aligner, and the uniformity of the illuminance distribution is within ±3π, and the uniformity of the illuminance distribution is within ±3π, and
In a reduction exposure apparatus such as No. 10, a value within ±2.5% is required. Methods for obtaining a uniform illuminance distribution and 1
However, since the uniformity correction plate has a loss of light intensity of about 30, it is difficult to manufacture it in these semiconductor exposure devices that require high illuminance. It has become necessary to obtain a uniform illuminance distribution without deteriorating the light experience.

Incidentally, lenses are usually designed to improve optical performance by reducing various aberrations such as spherical aberration, but it is impossible to eliminate these aberrations.

Due to this aberration, the light distribution of the light transmitted through the lens is uniform at a charge level of 1λ from the lens, but it cannot be uniform at positions different from this position. To explain this process with reference to FIG. 1, the light emitted from the inch grater lens 1 passes through the collimator lens 2. However, the distance between the lamps 2 and 2 is Ll TJI +
The illuminance distribution in LM is 1'), , 1), respectively.
, I)s. Immediately, the distance I7. The illuminance distribution at is uniform, but from this point, the distance 1 to the lens 2 is Jt.
1:1e T, 1 illuminance 1f' distribution ■) 1) The central part has a large illuminance and the peripheral part has a small illuminance. Conversely, the illuminance distribution 1) at a distance mL8, which is farther than the lens 2, has a central part. The illuminance is low and the peripheral area is large, so it no longer looks like the real thing when it comes to TL.1. ball. 1tE, in order to irradiate the wafer which is the object to be irradiated with this lens 2,
The position of the wafer is set at a distance I7. from lens 2. [Choose based on the point of intersection] 1.1- or 1 However, precision exposure equipment that bakes wafers, such as the semiconductor crush U, is often used in a clean room, and there is a demand for a smaller size 11. big.

For this reason, the distance between the lens and the object to be irradiated is also restricted, and it is often necessary to irradiate at a location closer to the lamp than at a location where the illuminance distribution is uniform, resulting in the problem of uneven illumination IW distribution. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to provide an illuminance distribution control method that can make the illuminance 1f distribution uniform according to the distance even when the distance between the lens and the object to be illuminated is restricted. When the light from the light source lamp is irradiated from the lens to the object to be irradiated at a predetermined position, the aberrations of the lens are reduced by using a lens design called pending, which changes only the shape without changing the focal length of the lens. In other words, the uninvented illuminance distribution control method uses pending methods to make the illuminance distribution uniform on the irradiated object. % ink to obtain illuminance distribution
be a sign.

Embodiments of the present invention will be specifically described below based on the drawings.

Figure 3 shows the basic optical system used in this lens.The light from the lamp 3 is reflected by the condenser 4 and exposed to the inch greater lens 1, and the emitted light is transmitted through the lens 2. The wafer is irradiated with parallel light. And the second
The figure shows the illuminance distribution when a pending operation is performed by changing only the shape of lens 2 without changing its focal length at a position where the distance from lens 2 is equal to the distance M I,+ in Figure 1. It is something that Here, the lens 2 shown in the center (d) is the same biconvex lens as the one shown in FIG. A small, non-uniform distribution is obtained by L, and a uniform distribution is obtained by a further distance (η.On the other hand, (
If a plano-convex lens is used as shown in C) and (e), the illuminance distribution will be considerably improved, but the distribution is not uniform as the Ij [I tail at the center of the lens is still larger than the periphery. If we proceed with this shape change and create a meniscus lens as shown in (1)) and (f), the distribution will be improved and a uniform illuminance distribution can be obtained, and this shape can be designed. . In addition, by further reducing the curvature of the lens, (a) and (g
), on the other hand, the illuminance in the central part becomes more unevenly distributed than in the peripheral part.

In this way, even if the distance between the lens and the object to be irradiated is predetermined, it is possible to make the population distribution at that distance uniform by the pending operation. An H-shaped lens can be provided. As a result, the light distribution on the magic light surface can be made within ±2.5% using only the lens system without using a uniform correction plate. In this example, an example is shown in which the light from a lamp is transmitted through one lens and the parallel light is irradiated onto the irradiated object. However, for example, it is possible to combine several lenses to form a condenser lens and transmit the light The situation is the same even when the light is focused and irradiated onto the object to be irradiated.

As explained in Explanation 1 above, the present invention makes the illuminance distribution more uniform than the pendimbutton ψf'pK that changes only the shape without changing the focal length of the lens, so the distance between the lens and the object to be irradiated is limited. The illuminance distribution at the platform that receives the light should also be adjusted according to the distance.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of the relationship between lens shape and M variation distribution, and Figure 3 is the basic optical system used. 1... Inch Greater Lens 2... Lens 3.
・・Lamp 4・・J & Mitsumitsu Ju Applicant Ushio Gunki Co., Ltd. 11 people Masu Riju FB Shintoranosuke - ~ n OOO

Claims (1)

[Claims] When the light from the light source lamp is irradiated from the lens to the irradiated object placed at a predetermined position, the illuminance distribution on the irradiated object is achieved by a lens designed with a pending design that changes only the shape without changing the focal length of the lens. An illuminance distribution control method characterized by making the brightness uniform.