JPS62187815A - Light quantity controller - Google Patents

Abstract

PURPOSE:To adjust the quantity of light to an irradiated surface properly by rotating an interference filter and varying the angle of incidence of incident luminous flux. CONSTITUTION:The interference filter 3 is rotated by a driving device 18 with a command signal from a monitor device 17 to vary the angle of incidence of the luminous flux I2, varying the quantity of transmitted light from the interference filter 3. Then two split pieces I1 and I2 of luminous flux are converged through a total reflecting mirror 4 and a half-mirror 5 and the output value of the total quantity of light is controlled. Thus, the light quantity control means consisting of the interference filter is provided on the optical path of one of plural split pieces of luminous flux to adjust the output of the total quantity of light.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an optical means for determining the amount of illumination light and exposure light-1.
The present invention relates to a light amount control device for controlling 11, and particularly to a light control device suitable for illuminating and exposing a reticle, a sea urchin, etc. using a beam from a laser in a conductor manufacturing device.

(Prior Art) Recent semiconductor technology has led to ever-increasing integration and miniaturization of electronic circuits, and optical exposure methods are also expanding their scope further due to the development of high-resolution lenses. In such exposure equipment for semiconductor manufacturing, when transferring and printing the circuit pattern of a mask or reticle onto the eight surfaces of the sea urchin,
Since the resolution line width of the circuit pattern printed on the eight faces of the sea urchin is proportional to the wavelength of the light source, in recent years Hg lamps have been used as light sources for ultraviolet rays, and ultra-high voltage Xe-Hg have been used for deep ultraviolet rays. ing.

However, resist sensitivity is low with such light, requiring a long exposure time and resulting in poor workability.

On the other hand, in recent years, a high-output light source called an excimer laser whose oscillation wavelength is in the far ultraviolet region has been used in various fields. This excimer laser has high brightness,
Because it is monochromatic and has a short coherence length, it is very effective for exposure equipment used in the production of V conductors.

Since the excitation method of this excimer laser is a discharge excitation method, the excimer laser is used as a light source of the illumination optical system for exposing the circuit pattern, and in order to maintain the exposure energy on the wafer surface at a predetermined value, the discharge excitation method is used. It is conceivable that this could be done by controlling the excitation voltage. However, if the excitation voltage becomes too large, the laser or excitation circuit will be destroyed, and conversely, if the excitation voltage becomes too small, the laser will no longer oscillate, so it is generally very difficult to control the excitation voltage and greatly change the output energy. .

Furthermore, since excimer lasers emit high-output pulses, the necessary exposure energy can usually be obtained with one to several pulses, and the pulse emission time is also 10 to 20 nsec.
It is difficult to precisely control the exposure energy by controlling the exposure time, which requires an ultra-high-speed shutter because the exposure time is very short.

(Problems to be Solved by the Invention) The present invention has a simple structure using an optical stage that can control the amount of exposure to a photosensitive material to an appropriate value in a stable state at all times and over a long period of time. In particular, the present invention aims to provide a light amount control device suitable for projecting and exposing a circuit pattern onto a photosensitive material surface such as a photoresist on a wafer surface. .

(Means for solving the problem) A light beam from a light source is divided into a plurality of light beams by a light splitting means, and a rotatable interference filter is arranged in the optical path of at least one of the plurality of light beams. , after changing the amount of light passing through the interference filter by changing the angle of incidence of the light beams on the interference filter, the plurality of light beams are condensed by a condensing member to control the total light amount. It is.

Other features of the invention are described in the Examples.

(Embodiment) FIG. 1 is a schematic configuration diagram of an embodiment in which the present invention is applied to an exposure apparatus for semiconductor manufacturing. In the figure, IO is a light source, for example, an injection locking type excimer laser. 11 is a light amount control device according to the present invention; 12 is an illumination optical system for illuminating an irradiated surface 14 such as a reticle or a mask; and 13 is a reflecting mirror, a portion of which is a semi-transmissive surface or a transmissive surface. Reference numeral 15 denotes a projection optical system for projecting a circuit pattern such as a reticle or mask on the irradiation surface 14 onto the projection surface 16, which is a surface for sea urchins.

17 is a monitoring device for monitoring the amount of light to the irradiated surface 14;
Reference numeral 18 denotes a drive device that drives the light amount control device 11 based on a command signal from the monitoring device 17.

In this embodiment, the illumination optical system illuminates the illuminated surface 14 while controlling the amount of light from the light source 1 to a predetermined value using the light amount control device 11. At this time, a part of the illumination light flux is taken out from a part of the reflecting mirror 13, and the monitoring device 17 monitors the amount of light to the irradiated surface. When the amount of light applied to the irradiated surface changes from a predetermined value, a command signal is sent to the drive device 18. The drive device 18 controls the light amount control device 11 based on the command signal, so that the light is always constant! Jk is used to illuminate the irradiated surface 14.

FIG. 2 is an explanatory diagram of an optical system of an embodiment of the light amount control device of the present invention. 1 in the figure is a light splitting means, for example, the transmittance is T,
It consists of a half mirror, and the incident light flux ■. The two luminous fluxes 1
．． ．． It is divided into I2.

Note that the number of divisions may be two or more. 2 is a total reflection mirror, and 3 is an interference filter, which can be rotated by the drive device shown in FIG. 4 is a total reflection mirror, and 5 is a half mirror.

In this embodiment, the total reflection mirror 4 and the half mirror 5 constitute a part of the condensing member.

In this embodiment, the interference filter 3 is rotated by the driving device 18 based on the command signal from the monitoring device 17, and the light beam 1
By changing the incident angle of the interference filter 3, the amount of light transmitted from the interference filter 3 is changed. Then, the two divided luminous fluxes 1.
．． I2 is focused by a total reflection mirror 4 and a half mirror 5, and the output value of the total light amount is controlled.

By providing a light amount control means consisting of an interference filter in the optical path of one of the plurality of light beams divided in this way, it is possible to adjust the output of the total light amount.

That is, the angle of incidence of the light beam on the interference filter is i. Then, the transmittance T(io) of the light flux from the interference filter is T(io)=1/(1+Fsin”(
δ/2) ) ・−(1). However, the thickness d,
Both sides of a transparent layer with a refractive index of n have a reflectance of r and a refractive index of n. of-
When the light is sandwiched between 7iI films and the refraction angle of light in the films is i, F=4r''/(1-r2)2.Sinlo=n6S!n!.

FIG. 3 is an explanatory diagram in which the incident angle 10 to the interference filter is plotted on the horizontal axis and the transmittance T is plotted on the vertical axis. As shown in the figure, the incident angle is i. By changing variously, an arbitrary amount of light can be transmitted through the interference filter.

From this, the amount of incident light is I +n, and the tip of the blade is I. When ut, the output light 1LLI+>ut becomes. (As is clear from the 2-channel type, in the actual 7IFi example, light splitting stages with different transmittances are replaced, and a light intensity control stage consisting of an interference filter is installed for some of the divided light beams.) By rotating and changing the angle of incidence of the light beam on the interference filter, the overall output light quantity is adjusted and coarsely adjusted.

That is, if the transmittance T1 is increased, the incident angle i. The change in the output light m I put due to the change in is small, and conversely, if the transmittance T1 is made small, the incident angle i. Output light Ht due to change in
. It is possible to increase the change in ut.

In this embodiment, the incident light beam is divided into two or more plural light beams by the light splitting means, and the light amount control means consisting of interference filters with different characteristics is installed in the optical path of each light beam. The amount of output light may also be controlled.

(Effects of the Invention) According to the present invention, it is possible to achieve a light amount control device that can appropriately adjust the amount of light to the irradiated surface with a simple configuration in which the interference filter is rotated to change the angle of incidence of the incident light beam. can.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention applied to an exposure apparatus for manufacturing semiconductors, FIG. 2 is a schematic diagram of an optical system of a light amount control device according to the present invention, and FIG. 3 is a diagram of the present invention. FIG. 3 is an explanatory diagram of the transmittance of the interference filter according to the invention. In the figure, 1 is a light splitting means, 2 and 4 are total reflection mirrors, 3 is an interference filter, 5 is a half mirror, 110 is a light source, 11 is a light amount control device, 12 is an illumination optical system, 13 is a reflecting mirror, and 14 is an irradiated object 15 is a projection optical system, 16 is a projection surface, +7 is a monitoring device, and 18 is a drive device.

Claims (2)

[Claims] (1) A light beam from a light source is divided into a plurality of light beams by a light splitting means, a rotatable interference filter is arranged in the optical path of at least one of the plurality of light beams, and the light beam is directed to the interference filter. A light amount control device, characterized in that the amount of light transmitted through the interference filter is changed by changing the incident angle, and then the plurality of light beams are condensed by a condensing member to control the total amount of light. (2) The light amount control device according to claim 1, wherein the light source is a laser, and the condensing member is a half mirror and a total reflection mirror.