JP3745822B2 - Excimer laser oscillation device and stepper device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an excimer laser oscillating device used for processing metals, resins, glass, ceramics, semiconductors, and the like and chemical reactions, and more particularly to an excimer laser oscillating device excellent in laser energy and beam shape stability.
[0002]
[Prior art]
Excimer lasers are attracting attention as the only high-power lasers that oscillate in the ultraviolet region, and are expected to be applied in the electronics, chemical and energy industries.
[0003]
An apparatus that generates excimer laser light is known as an excimer laser oscillation apparatus. Laser gas such as Ar, Kr, Xe, KrF, and ArF filled in the manifold is excited by electron beam irradiation or discharge. The excited atoms then combine with the ground state atoms to produce molecules that exist only in the excited state. This molecule is called an excimer. Since excimer is unstable, it immediately emits ultraviolet light and falls to the ground state. This is called a bond-free transition, and an excimer laser oscillation device is a device that multiplies ultraviolet light obtained by this transition in an optical resonator composed of a pair of mirrors and extracts it as laser light.
[0004]
First, the excimer laser system will be described with reference to FIG.
[0005]
In FIG. 2, A01 is a laser chamber, A02 is a narrow-band module for controlling the line width of the oscillation line, A03 is a high-pressure pulse power module, and A04 is an optical monitor that measures the energy intensity and wavelength of the oscillated laser. A module, A05 is a high-voltage power supply, and A06 is a controller that controls the entire excimer laser system.
[0006]
When the excimer laser system is used as an exposure light source for a stepper, the computer controller A06 is connected to a stepper control unit A31, a stepper computer A32, and the like via an interface A30.
[0007]
For example, a gas such as F ₂ , Kr, or Ne is sealed in the laser chamber A01. When a high-pressure pulse is applied from the pulse power module A03 to the cathode electrode in the laser chamber, the gas is discharged and light emission is started. The light is repeatedly reflected between the output mirror A07 and the optical system in the narrowband module A02, amplified, and emitted to the outside.
[0008]
In order to obtain a laser beam having a desired wavelength, a part of the emitted laser beam is guided to the optical monitor module A04 by the half mirror A08, and the wavelength of the light is measured. Based on this result, the stepping motor A09 When driven, the optical system of the narrowband module A02 is optimized. Also, the power of the laser beam is constantly monitored by this optical monitor module.
[0009]
FIG. 1 is a schematic view of a cross section perpendicular to the laser beam oscillation direction of the laser chamber A01.
[0010]
As shown in FIG. 1, the laser chamber A01 includes two aluminum housing members A11 and A12 and is sealed by an O-ring A13. A cathode electrode A16 is fixed to the chamber A01 via an insulator A14 and a cathode electrode support member A15, and an anode electrode A17 is fixed to the housing member via an anode electrode support member A18. A20 is a connector for connecting the cathode electrode A16 and the pulse oscillator A03. A19 is a sealing member such as an O-ring.
[0011]
Inside the laser chamber A01, a blower A20 for circulating gas and a heat exchanger A21 for cooling the gas heated in the discharge section are arranged. The laser chamber A01, the blower A20, and the heat exchanger A21 are made of stainless steel or aluminum alloy, and their outer surfaces are usually subjected to electrolytic polishing or bright annealing. In addition, a filter A22 is attached to the housing, and gas is introduced through the gas inlet A23 to remove metal fluoride particles and the like generated by the reaction between the electrode metal in the gas and fluorine gas.
[0012]
Next, with reference to FIG. 3, the gas supply system previously conceived by the present inventors will be described.
[0013]
In the example of FIG. 3, there are three gas supply lines: a gas supply line C01 of 1% Kr / Ne gas, a supply line C01 ′ of 1% F ₂ /1% Kr / Ne gas, and a supply line C01 ″ of He gas. Each gas supply line is provided with orifices C02, C02′C02 ″ for flow rate adjustment, valves C03, C03 ′, C03 ″, and are connected to a manifold C04. Used as a purge gas when the chamber window plate is replaced.
[0014]
The manifold C04 is provided with a chamber valve C06 and a valve C07 in the gas supply connecting pipe C05. The manifold C04 is connected to an F ₂ gas supply pipe C08, and is connected to the connecting pipe C05 via an injection valve C09 and a flow rate control orifice C10.
[0015]
C12 is a spring valve that opens when the pressure in the manifold C04 rises abnormally. C13 is a manifold exhaust line, and C14 is a valve provided so that the inside can be exhausted, for example, when an abnormality occurs in the laser chamber. C15 is an F ₂ gas abatement device, and C16 is an exhaust pump. P indicates a pressure gauge.
[0016]
When the F ₂ gas concentration of the laser discharge gas is 0.1%, the method of filling the gas with this concentration in the chamber is as follows. First, 1% F ₂ /1% Kr / Ne gas is introduced into the chamber C11 through the manifold C04 and the pipe C05 while monitoring with a pressure gauge until the pressure reaches, for example, 30 kPa, and then 1% Kr / Ne gas is introduced. Introduce until 300 kPa. In this way, a mixed gas containing 0.1% F ₂ is introduced into the chamber.
[0017]
In the above excimer laser oscillation apparatus, when the oscillation is repeated, the output of the laser decreases. Therefore, it is necessary to periodically replace parts such as the chamber. On the other hand, even within the lifetime of these parts, the laser output may decrease. In this case, a method of increasing the voltage applied to the discharge electrode to restore the output has been adopted.
[0018]
It has been found that one of the causes of the decrease in the laser output is due to the decrease in the F ₂ gas concentration. Therefore, a countermeasure is taken by periodically supplying a predetermined amount of 1% F ₂ /1% Kr / Ne gas to the chamber C11 through the manifold C04 and the pipe C08.
[0019]
However, even if the F ₂ gas is replenished, it is not clear how much F ₂ concentration is present in the chamber, and a method of periodically replenishing the F ₂ gas after oscillating a fixed number of pulses must be taken. I didn't get it. Therefore, if the replenishment is repeated, the F ₂ concentration may be largely deviated from the initial concentration, and there is a problem that the stability of the pulse output is lacking.
[0020]
Therefore, in order to obtain a stable pulse output, it is necessary to detect the concentration of the F ₂ gas itself.
[0021]
As a general gas analysis method, gas chromatograph (GC) is often used, but it is generally considered that it is not suitable for the analysis of highly reactive substances (Chemical Doujinsha “Instrumental analysis”). Telebiki (2) ", page 217, lines 5-6). Since F ₂ gas is a highly reactive substance, the concentration measurement of F ₂ gas has not been considered in the gas supply system of excimer laser.
[0022]
The present invention has been made for the purpose of extending the stability and life of laser oscillation without being caught by such conventional common sense.
[0023]
On the other hand, if laser oscillation is repeated, the discharge gas becomes unstable due to the gas released from the members in the laser chamber, etc., and the leakage gas from the outside and the impurities in the introduced discharge gas accumulate. Cannot be obtained. It has also been found that the problem arises that F ₂ gas reacts with impurities and is consumed. Therefore, it is necessary to replace the entire discharge gas when the impurity reaches a certain concentration or more, and the discharge gas is replaced after oscillating a fixed number of pulses. However, since the accumulated amount of impurities is not always the same, the total number of pulses until gas exchange must be set low, and the efficiency is low.
[0024]
The above problems were found by the present inventors in the process of developing an excimer laser device having superior output stability and lifetime, and the present invention has been completed based on the discovery of these problems. It has come.
[0025]
[Problems to be solved by the invention]
In such a situation, the present invention provides a means for measuring the F ₂ gas concentration in the laser chamber, and excimer laser capable of keeping the output of the pulse laser stable for a long period of time by keeping the F ₂ concentration in a certain range. An object is to provide an apparatus.
[0026]
Another object of the present invention is to provide an excimer laser oscillating device having high efficiency by measuring the impurity gas in the laser chamber to reduce the frequency of laser gas exchange.
[0027]
Furthermore, another object of the present invention is to provide a stepper apparatus that can repeatedly expose a fine pattern of 0.25 μm or less stably for a long period of time.
[0028]
[Means for Solving the Problems]
The excimer laser oscillation device of the present invention is an excimer laser oscillation device having a gas chromatograph device for detecting the F ₂ gas concentration in the laser chamber of the excimer laser oscillation device,
At least the surface of the separation column packing in the gas chromatograph is AlF ₃ , MgF ₂ or CaF ₂ .
A stepper device according to the present invention includes the excimer laser oscillation device and a stage for moving a substrate.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
The excimer laser device of the present invention has a gas chromatograph device for detecting the F ₂ gas concentration in the laser chamber, and periodically or constantly measures the F ₂ gas concentration in the discharge gas, and when it becomes below a predetermined concentration. In this configuration, F ₂ gas is replenished and can always be maintained within a desired concentration range.
[0030]
When laser oscillation is repeated, impurities such as H ₂ O, O ₂ and H ₂ gas are released from the inner wall of the laser chamber, and the discharge gas is gradually polluted by external leakage, so that the discharge does not occur. Become stable. Therefore, the gas chromatograph apparatus can simultaneously measure the concentration of the reaction product with these impurity gases and / or F ₂ gas, and preferably replaces the entire gas when the concentration exceeds a predetermined concentration.
[0031]
FIG. 4 shows an example of the excimer laser device of the present invention. A gas sampling tube 420 is attached to the laser chamber having the structure of FIG. 1, and this sampling tube is connected to a sample inlet 407 of the gas chromatograph apparatus 400 via a valve 421.
[0032]
4, 401 is a carrier gas cylinder, 402 is a pressure reducing valve, 403 is a fine adjustment valve, 404 is a pressure gauge, 405 is a flow meter, 406 is a preheating tube, 407 is a sample inlet, 408 is a separation column, and 409 is a detector. , 410 is an amplifying device, 411 is a vaporizer constant temperature layer, 412 is a vaporizer temperature controller, 413 is a column thermostat, and 414 is a column temperature controller. Reference numeral 415 denotes a recorder, which can be replaced by a computer. Reference numeral 416 denotes a flow meter.
[0033]
In the gas chromatograph apparatus 400, the gas piping system such as the gas sampling pipe 420 and the valve 421, and the portion that contacts the F ₂ gas such as the separation column 408 and the detector 409 preferably form a fluorinated passive film. Corrosion due to F ₂ gas can be prevented and gas adsorption is less likely to occur, and high-precision measurement of F ₂ gas concentration is possible.
[0034]
As the column filler, fluorides such as AlF ₃ , MgF _{2, and} CaF ₂ are preferably used. In addition, various fillers that have been fluorinated can be used. Thereby, the measurement accuracy of the F ₂ gas concentration is further improved.
[0035]
Next, taking a gas pipe as an example, a method of forming a fluorinated passive film on the inner surface of the pipe will be described. The inside of the separation column, valve, and detector may be similarly fluorinated. Stainless steel is usually used for members such as gas pipes.
[0036]
First, the inner surface of the pipe is mirror-polished by electropolishing or a composite electropolishing method, and then, if desired, baking is performed in order to evaporate moisture or deposits. This baking is desirably performed within a range of 150 to 450 ° C. The baking time is preferably about 1 to 6 hours.
[0037]
The fluorination treatment is usually performed using fluorine alone or a fluoride gas while filling or flowing this gas into the stainless steel pipe. The temperature of the fluorination treatment is preferably 200 to 600 ° C, more preferably 300 to 600 ° C. This is because if it is less than 200 ° C., sufficient fluorination treatment may not be performed, and if it exceeds 600 ° C., a homogeneous fluorinated passive film is not formed. The fluorination treatment time is preferably 1 to 6 hours. Although the ratio of FeF ₂ , FeF ₃ , and CrF _{3 in} the fluorinated passivated film varies depending on the fluorination treatment conditions, it is preferable to form a fluorinated passivated film containing FeF ₂ as a main component.
[0038]
It should be noted that a thicker fluorinated passive film is formed as the temperature during the fluorination treatment is higher. Even at the same fluorination temperature, the passive film tends to be thicker as the baking temperature is higher.
[0039]
After the fluorination treatment, heat treatment is preferably performed in an inert gas atmosphere such as N ₂ , Ar, or He gas for 1 to 24 hours. The heat treatment temperature is preferably 200 to 600 ° C, more preferably 300 to 600 ° C. By performing the heat treatment, the passive film is in a dense structure.
[0040]
The thickness of the fluorinated passive film by the fluorination treatment is preferably 20 to 500 nm. An alloy material having a thick passive film is more excellent in corrosion resistance. However, if the thickness exceeds 500 nm, peeling may occur, and therefore the thickness is preferably 500 nm or less. 100 to 200 nm is more preferable.
[0041]
Further, after the Ni-P plating or Ni-W-P plated stainless pipe inner surface, may form a fluoride passivated film made of NiF ₂ and fluorinated. In this case, in order to release gas from the inside of the Ni plating film and remove contaminants on the surface, it is washed with water, dried, baked in an inert gas such as N ₂ gas, and then fluorinated with F ₂ gas, A fluorinated passive film made of NiF ₂ is formed. Thereafter, heat treatment is performed in an inert gas.
[0042]
In this case, baking temperature is 200-390 degreeC, Preferably it is 250-350 degreeC. The baking time is preferably about 1 to 6 hours. The subsequent fluorination treatment temperature is 200 to 390 ° C, preferably 250 to 380 ° C. The fluorination treatment time is 1 to 6 hours. The heat treatment temperature is 250 to 390 ° C, preferably 330 to 380 ° C. This heat treatment may be N _2, Ar, be carried out 1 to 5 hours in a robust and dense in an inert gas atmosphere such as He, to form a good fluoride passivated film corrosion resistance.
[0043]
In addition, when the column filler is fluorinated, in addition to the case where the filler itself is fluorinated by the above-described method, a metal film is formed on the surface, and this is brought into contact with F ₂ gas or the like. You can also
[0044]
Examples of embodiments of the present invention are shown below.
[0045]
Embodiment Example 1
An excimer laser oscillating device comprising a gas chromatograph device for detecting an F ₂ gas concentration in a laser chamber of an excimer laser oscillating device.
[0046]
Embodiment Example 2
The excimer laser oscillation apparatus according to the first embodiment is characterized in that the gas chromatograph apparatus can simultaneously detect the impurity gas concentration in the laser chamber of the excimer laser oscillation apparatus.
[0047]
Embodiment Example 3
The excimer laser oscillation apparatus according to the embodiment 1 or 2, wherein a fluorinated passive film is formed on the gas piping system, the separation column, and the inner surfaces of the detector of the gas chromatograph apparatus.
[0048]
(Embodiment example 4)
The excimer laser oscillation apparatus according to any one of Embodiments 1 to 3, wherein at least a surface of the separation column packing of the gas chromatograph apparatus is a fluoride.
[0049]
(Embodiment example 5)
A stepper device comprising the excimer laser oscillation device according to any one of the embodiment examples 1 to 4 and a stage for moving the substrate.
[0050]
【Example】
An excimer laser oscillation apparatus of this example is shown in FIG. 5, the same reference numerals as those in FIG. 3 indicate the same members as those in FIG. In FIG. 5, in order to increase the accuracy of the replenishment amount of 1% F ₂ gas, the mass flow controller 501 can precisely control the replenishment amount of F ₂ gas. The inner surface of the piping in the gas path from the fluorine gas source to the chamber is fluorinated.
[0051]
502 is a tube for collecting gas in the laser chamber, 502 is a valve, and 504 is the gas chromatograph apparatus shown in FIG.
[0052]
SUS316L is used for the gas sampling tube 502, valve 503, separation column, and detector substrate of the gas chromatograph apparatus, and the inside is mirror-polished by electropolishing, followed by baking at 300 ° C. for 2 hours, 300 ° C. for 1 hour. Fluorine treatment with F ₂ gas, and N ₂ gas heat treatment at 450 ° C. for 1 hour. By these treatments, a 200 nm fluoride passivation film was formed on the surface of SUS316L.
[0053]
Using these members, a mixed filler of CaF ₂ , MgF ₂ and AlF ₃ was filled in a separation column, a gas chromatograph apparatus was assembled, the interior was sufficiently purged, and then connected to the laser chamber C11.
[0054]
Next, the discharge gas containing 0.1% F ₂ gas was filled in the laser chamber C11 as follows.
[0055]
First, the mass flow controller 501 was set to a predetermined flow rate, and 1% F ₂ /1% Kr / Ne gas was flowed for a predetermined time and introduced into the chamber. Next, similarly, the mass flow controller 501 was set to a predetermined flow rate, and 1% Kr / Ne gas was allowed to flow for a predetermined time to be introduced into the laser chamber. Here, the gas introduction ratio (flow rate x time) was 1: 9.
[0056]
In this state, the laser is repeatedly oscillated, the valve 502 is periodically opened, the discharge gas is introduced into the gas chromatograph, and the F ₂ gas concentration and impurities such as H ₂ , H ₂ O, 0 _{2 and} HF gas are introduced. perform measurements, at the stage of lowering F ₂ gas concentration below 0.095%, the _{1% F 2/1% Kr} / Ne gas amount necessary to the F ₂ gas concentration of 0.1% The laser chamber C11 was replenished via the manifold C04, the pipe C08, the mass flow controller 501, and the valve C07.
[0057]
As described above, the F ₂ gas concentration can be maintained within a certain concentration range, and stable laser oscillation can be obtained.
[0058]
Moreover, since the change was grasped from the measured value of the impurity gas concentration, it became possible to predict the replacement timing of the entire discharge gas.
[0059]
If a substrate (wafer) placed on a moving stage is exposed through a mask using this laser transmitter as a plateau, a fine pattern can be printed.
[0060]
【The invention's effect】
According to the present invention, it is possible to always maintain the F ₂ gas concentration in the discharge gas within a certain range, and it is possible to maintain a stable laser oscillation with uniform pulse energy and high accuracy.
[0061]
Further, according to the present invention, by measuring the impurity gas in the laser chamber, it is possible to reduce the replacement frequency of the laser gas, and it is possible to provide a highly efficient excimer laser oscillation device.
[0062]
Furthermore, the present invention can provide a stepper capable of performing ultra-fine, high-precision and stable resist exposure.
[Brief description of the drawings]
FIG. 1 is a conceptual cross-sectional view showing the structure of a laser chamber.
FIG. 2 is a system diagram showing an excimer laser oscillation apparatus.
FIG. 3 is a system diagram showing gas supply to a laser chamber.
FIG. 4 is a conceptual diagram of an excimer laser device having a gas chromatograph device that detects a gas concentration in a laser chamber.
FIG. 5 is a system diagram showing a gas supply system to a laser chamber and a gas chromatograph apparatus.
[Explanation of symbols]
A01 laser chamber,
A02 A narrowing module for controlling the line width of the oscillation line,
A03 High-pressure pulse power module,
A04 Optical monitor module for measuring the energy intensity and wavelength of the oscillated laser,
A05 High voltage power supply,
A06 Controller that controls the entire system,
A07 output mirror,
A09 stepping motor,
A11, A12 housing member,
A13 O-ring,
A14 insulator,
A15 Cathode electrode support member,
A16 cathode electrode,
A17 Anode electrode,
A18 Anode electrode support member,
A20 connector,
A19 Sealing member such as O-ring,
A20 blower,
A21 heat exchanger,
A22 filter,
A23 Gas intake,
C01 gas supply line,
C01 ′ 1% F ₂ /1% Kr / Ne gas supply line,
C01 ”He gas supply line,
C02, C02'C02 "orifice,
C03, C03 ', C03 "valves,
C04 manifold,
C05 connecting piping,
C06 chamber valve,
C07 valve,
C08 F ₂ gas supply piping,
C09 injection valve,
C10 orifice for flow control,
C11 chamber,
C12 spring valve,
C13 Manifold exhaust line,
C14 valve,
C15 F ₂ gas exclusion device,
C16 exhaust pump,
p Pressure gauge.
400 gas chromatograph,
401 carrier gas cylinder,
402 pressure reducing valve,
403 fine adjustment valve,
404 pressure gauge,
405 flow meter,
406 preheating tube,
407 Sample inlet,
408 separation column,
409 detector,
410 amplifying device,
411 vaporizer constant temperature layer,
412 vaporizer temperature control device,
413 column thermostat,
414 column temperature controller,
415 recorder,
416 flow meter,
420 gas sampling tube,
421 valve,
501 flow meter,
502 gas sampling tube,
503 valve,
504 Gas chromatograph device.

Claims (2)

An excimer laser oscillation device having a gas chromatograph device for detecting the F ₂ gas concentration in the laser chamber of the excimer laser oscillation device,
An excimer laser oscillation device characterized in that at least the surface of the separation column packing of the gas chromatograph device is AlF ₃ , MgF ₂ or CaF ₂ . A stepper device comprising the excimer laser oscillation device according to claim 1 and a stage for moving a substrate.

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