JP2661082B2 - Laser wavelength control apparatus and exposure apparatus using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser wavelength controller and an exposure apparatus using the same, and more particularly, to a mask on which an electronic circuit pattern is formed in the manufacture of semiconductor elements such as ICs and LSIs. The present invention relates to a laser wavelength controller suitable for illuminating a reticle or the like with a laser, for example, an excimer laser, and exposing and transferring a pattern on the reticle surface onto a wafer surface, and an exposure apparatus using the same. (Prior Art) Conventionally, in an optical lithography technique, a light source that oscillates light in a far ultraviolet region having a small diffraction effect has been used in order to achieve high-density integration and ultra-miniaturization of semiconductor elements. There is an excimer laser as a light source that oscillates in the far ultraviolet region and has excellent high brightness, monochromaticity and directivity. I have. In general, a single glass material of quartz is used as a glass material constituting a projection lens used in an excimer stepper, which has a constant transmittance in the far ultraviolet region and has a workability and uniformity at the present time. When the projection lens is made of single quartz, chromatic aberration cannot be corrected. Therefore, a light source used for this purpose is required to have a constant oscillation wavelength from the viewpoint of resolving power and the like. That is, the deviation of the oscillation wavelength becomes a deviation of the focus position and the magnification, and has a significant influence on the resolving power and the resolving dimension. When a current excimer laser is used for a stepper, it is necessary to narrow the spectrum width and stabilize the oscillation wavelength. The narrowing of the band of an excimer laser is usually performed by incorporating a wavelength selection element in a laser resonator and forcibly oscillating only a specific wavelength within the natural emission spectrum width of the excimer laser. In addition, a wavelength detector is provided to stabilize the oscillation wavelength, and the angle and the like of the above-mentioned wavelength selection element are controlled based on this data to keep the wavelength constant. 2 and 3 are schematic diagrams each showing a part of a conventional wavelength detecting device for detecting an oscillation wavelength from a laser. FIG. 2 shows a pattern obtained by detecting a fringe formed by the etalon 33 of the laser beam 23 passing through the concave lens 31 and the aperture 32 as a detector.
D34 is projected onto the surface, and the fringe spacing at that time is
, The amount of deviation from a certain oscillation wavelength is detected. FIG. 3 shows that a light beam that has passed through a stop 41 and a magnifying optical system 42 is made incident on a grating 43, which constitutes a normal spectral system, and a convex lens 44 serves as a detector.
The light is condensed on the surface of the CCD 45, and the position of the luminescent spot at that time is obtained by the signal detection unit 47 to detect the wavelength of the laser beam 23. Generally, wavelength detectors are required to have extremely strict accuracy. For this reason, for example, the holding precision of the optical material and the detecting element constituting the wavelength detecting device is severe. For example, in the wavelength detector shown in FIG. 2, the parallelism distance between the two elements 33 becomes important, and in the wavelength detector using the grating shown in FIG. 3, the grading holding angle accuracy becomes important. come. (Problems to be Solved by the Invention) The oscillation wavelength from the laser is directly affected by the density of the medium in the optical path. For this reason, if the wavelength detector is placed in a normal environment, environmental changes, such as changes in temperature, pressure, and humidity, cause expansion and contraction of the optical element, the detection element, and their holders. Further, a change in the density of the medium in the optical path causes an error in the measurement for stabilizing the wavelength, and changes the oscillation wavelength of the laser. As a result, the resolution performance of the semiconductor exposure apparatus is significantly affected. Even if the semiconductor exposure apparatus has focus and magnification correction means, if the wavelength cannot be accurately measured, the correction means cannot be used effectively. SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser wavelength control device capable of detecting a wavelength with high accuracy and thereby controlling an oscillation wavelength from a laser with high accuracy, and an exposure apparatus using the same. (Means for Solving the Problems) The laser wavelength controller of the present invention comprises: (1-1) a wavelength detecting means for detecting the wavelength of laser light, and the laser light using an output signal from the wavelength detecting means. A laser wavelength control device having a wavelength control means for controlling the wavelength of the light, wherein a storage means for storing an optical system of the wavelength detection means, and a mechanism for supplying and exhausting gas in the storage means, wherein the gas And a pressure adjusting means for adjusting the pressure. In particular, (1-1-1) a mechanism for heating and cooling the gas in the storage means is provided, and a temperature adjusting means for adjusting the temperature of the gas is provided. An exposure apparatus according to the present invention includes: (2-1) an exposure apparatus that performs exposure using laser light from a laser, wherein: the wavelength detection means for detecting the wavelength of the laser light; and the laser using an output signal from the wavelength detection means. Pressure control for controlling the pressure of the gas, comprising: a wavelength control means for controlling the wavelength of light; a storage means for storing the optical system of the wavelength detection means; and a mechanism for supplying and exhausting gas in the storage means. Means. In particular, (2-1-1) a mechanism for heating and cooling the gas in the storage means is provided, and a temperature adjusting means for adjusting the temperature of the gas is provided. The method for manufacturing a semiconductor device according to the present invention includes: (3-1) exposing a pattern on a mask surface onto a wafer surface by laser light from a laser, and developing the wafer to manufacture a semiconductor device. In the method, wavelength detecting means for detecting the wavelength of the laser light, wavelength controlling means for controlling the wavelength of the laser light using an output signal from the wavelength detecting means, and storing means for storing an optical system of the wavelength detecting means. And a mechanism for supplying and exhausting the gas in the storage means, and a pressure adjusting means for adjusting the pressure of the gas. In particular, (3-1-1) a mechanism for heating and cooling the gas in the storage means is provided, and a temperature adjusting means for adjusting the temperature of the gas is provided. (Embodiment) FIG. 1 is a block diagram of one embodiment of the present invention. In the figure, reference numeral 1 denotes a laser, and 2 denotes a wavelength control mechanism, which is provided in the laser 1 and controls the oscillation wavelength of the laser 1. Reference numeral 3 denotes a half mirror which divides the beam 23 from the laser 1 into an exposure apparatus for manufacturing a semiconductor element and an apparatus for measuring wavelength according to the present invention. Of the beam 23, the beam split by the half mirror 3 to the exposure device illuminates a known pattern on the mask surface and is used as light for exposing and transferring the pattern onto the wafer surface. Then, a semiconductor element is manufactured through a known developing process on the wafer that has been exposed and transferred by the exposure apparatus. 4 is a total reflection mirror, 8 is an entrance window, 5 is a wavelength detection unit (wavelength detection means), which reflects the wavelength of the beam 23 from the laser 1 reflected by the total reflection mirror 4 and passing through the entrance window 8, for example. 2. Detection is performed using the method shown in FIG. 6 is a laser wavelength control unit (wavelength detection means),
The signal from the wavelength detector 5 is analyzed to drive the wavelength control mechanism 2 to control the oscillation wavelength from the laser 1. The laser wavelength control section 6 and the wavelength control mechanism 2 constitute a part of the wavelength variable control means. 9 is a cooling unit, 10 is a heating unit, 11 is a temperature sensor, 12 is a pressure sensor, and 7 is a chamber (container). An environment control unit such as a cooling unit 9, a heating unit 10, a temperature sensor 11, and a pressure sensor, and a wavelength detection unit 5 are both housed in a chamber 7 serving as a storage means. The state is controlled so that it is always under a certain condition. As a result, the wavelength detector 5 in the chamber 7 always operates under a constant environmental condition. Reference numeral 13 denotes a heating control unit which controls the heating unit 10. A cooling device 14 controls the cooling unit 9. Reference numeral 15 denotes a valve drive unit, which includes an exhaust control valve 16 and a pressurization control valve 17.
Is being driven. Reference numeral 18 denotes an air filter, and 19 denotes a chamber control unit, which sends control signals to the temperature sensor 11 and the pressure sensor 12, the heating control unit 13, the cooling device 14, and the valve driving unit 15. Reference numeral 20 denotes an input device which inputs data relating to environmental conditions in the chamber 7 to the chamber control unit 19. Reference numeral 21 denotes an exhaust pump that exhausts gas in the chamber 7 to reduce the pressure in the chamber 7. A pressure pump 22 supplies gas into the chamber 7 to pressurize the chamber 7. In this embodiment, as shown in the figure, the laser 1 forms one closed loop by the wavelength detection unit 5, the laser wavelength control unit 6, and the wavelength control mechanism 2, and the wavelength of the beam 23 from the laser 1 is always a constant value. It is maintained to be. In the present embodiment, the environmental state in the chamber 7 is controlled so as to be always constant, and the wavelength detector 5 provided in the chamber 7 is kept in a constant environment to perform the detecting operation. Next, the atmospheric pressure of humidity will be described as an example of a method of controlling the environmental state in the chamber 7. The set temperature data T ₀ in the chamber 7 by the input device 20
And entering the set pressure data P _0, further by entering the control start command comprising command chamber controller 19 may enter the measured values P ₁ measured value T ₁ and a pressure sensor 12 of the temperature sensor 11 to read the destination The temperature data T ₀ and the pressure data P ₀ are compared. At this time, if T ₁ > T ₀ , a cooling control signal is sent to the cooling device 14 to drive the cooling unit 9, and if T ₁ <T ₀ , a heating control signal is sent to the heating control unit 13 and the heating unit
Drive 10 If P ₁ > P ₀ , an exhaust control valve drive signal is sent to the valve drive unit 15 to drive the exhaust control valve 16. If P ₁ <P ₀ , a pressure control valve drive signal is sent to the valve drive unit 15 to drive the pressure control valve 17. still,
The exhaust pump 21 and the pressure pump 22 are in operation beforehand. In this way, finally, the environment in the chamber 7 is controlled so that T ₁ = T ₀ and P ₁ = P ₀ so that the values of the set temperature data T ₀ and the set pressure data P ₀ previously input are set. ing. In the above-described embodiment, the input device 20 previously sets the set temperature tolerance Δ along with the set temperature T ₀ and the set pressure P _0.
T and the set pressure receptor ΔP are input, and the tolerances are compared in the comparison between the measured value T ₁ of the temperature sensor 11 and the measured value P ₁ of the pressure sensor 12 with the set temperature data T ₀ and the set pressure data P _0. This may be performed in consideration of ΔT and ΔP. That is, when T ₁ > T ₀ + ΔT / 2 and T ₁ <T ₀ −ΔT / 2, a cooling control signal and a heating control signal are sent, respectively, and P ₁ > P ₀ +
At the time of ΔP / 2 and P ₁ <P ₀ −ΔP / 2, if the exhaust control valve drive signal and the pressurization control valve drive signal are transmitted, respectively, T ₀ + ΔT / 2> T ₁ > T ₀ −ΔT / 2, P ₀ + ΔP /
2> P ₁ > P ₀ −ΔP / 2, and the internal environmental state in the chamber 7 can be controlled within the range of the tolerances ΔT and ΔP. Also, it keeps always operating a cooling device 14 in the temperature control, cooling by the cooling unit 9 is always may be kept to be equal to or less than the set temperature data T ₀ when no heating control. In this case, the internal temperature of the chamber 7 can be controlled only by the heating control by the heating unit 10. In addition, in the above embodiments, a temperature detection unit and a control unit for humidity are provided in addition to the temperature and pressure as the environment control unit, and the temperature,
It is preferable to control the wavelength detector in the same manner as the pressure because the wavelength detector can be operated under more favorable environmental conditions. (Effects of the Invention) According to the present invention, a detection error at the time of wavelength detection due to a disturbance such as a pressure change can be reduced, and an oscillation wavelength from a laser can always be maintained within a certain range, so that wavelength fluctuation is severely restricted. When applied to an apparatus such as a stepper using an excimer laser, a reduction in resolution performance can be prevented, and there are effects such as higher performance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of one embodiment of the present invention, FIG.
FIG. 1 is a schematic diagram of a conventional wavelength detecting device. In the figure, 1 is a laser, 2 is a wavelength control mechanism, 3 is a half mirror, 5 is a wavelength detector, 6 is a laser wavelength controller, 7 is a chamber (container), 8 is an entrance window, 9 is a cooling unit, 10
Is a heating unit, 11 is a temperature sensor, 12 is a pressure sensor, 13
Is a heating control unit, 14 is a cooling device, 19 is a chamber control unit,
20 is an input device.

Claims (1)

(57) [Claims] In a laser wavelength control device having a wavelength detecting means for detecting the wavelength of the laser light, and a wavelength controlling means for controlling the wavelength of the laser light using an output signal from the wavelength detecting means, an optical system of the wavelength detecting means A laser wavelength control device, comprising: a storage unit for storing the gas; and a pressure adjusting unit for adjusting a pressure of the gas, the mechanism having a mechanism for supplying and exhausting gas in the storage unit. 2. 2. The laser wavelength control device according to claim 1, further comprising a mechanism for heating and cooling the gas in said storage means, and a temperature adjusting means for adjusting the temperature of said gas. 3. In an exposure apparatus for performing exposure by laser light from a laser, a wavelength detecting means for detecting a wavelength of the laser light, a wavelength control means for controlling a wavelength of the laser light using an output signal from the wavelength detecting means, and the wavelength An exposure apparatus comprising: storage means for storing an optical system of a detection means; and a pressure adjusting means having a mechanism for supplying and exhausting gas in the storage means, and adjusting pressure of the gas. 4. 4. The exposure apparatus according to claim 3, further comprising a mechanism for heating and cooling the gas in the storage unit, and a temperature adjustment unit for adjusting the temperature of the gas. 5. In a method of manufacturing a semiconductor device, a pattern on a mask surface is exposed on a wafer surface by laser light from a laser, and the wafer is subjected to a developing process to manufacture a semiconductor device.
Wavelength detection means for detecting the wavelength of the laser light, storage means for storing an optical system of the wavelength detection means, and a wavelength control means for controlling the wavelength of the laser light using an output signal from the wavelength detection means, A method of manufacturing a semiconductor device, comprising: a mechanism for supplying and exhausting gas in a storage means; and a pressure adjusting means for adjusting a pressure of the gas. 6. 6. The method of manufacturing a semiconductor device according to claim 5, further comprising a mechanism for heating and cooling the gas in the storage means, and a temperature adjusting means for adjusting the temperature of the gas.