JPH07283123A - Controller of quantity of light for irradiation and aligner employing it - Google Patents

Abstract

PURPOSE:To control with high precision the quantity of light for irradiation onto a surface by a method wherein, when it is decided that the quantity of light for irradiation reaches a previously set value, the reflectance is a predetermined value, and by changing the distance between the two mirrors of an etalon provided in an optical path by a piezoelement, the transmittance of the etalon is controlled. CONSTITUTION:The quantity of each pulse light emitted by an excimer laser 1 is measured by monitoring means 7. An integration value and a mean value of the exposure quantity is obtained by central controlling means 4. When the central control device 4 decides that the exposure of a wafer 9 reaches the necessary integration exposure quantity with exposure energy of one pulse or less, the then insufficient quantity of light is computed. Drive controlling means 3 changes an interval of etalon so that the transmittance may be a value at which the quantity of light equivalent to the insufficient quantity of light can pass based upon a signal from the central controlling means 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an irradiation light quantity control apparatus and an exposure apparatus using the same, and more particularly, to an irradiation surface, for example, an electronic circuit pattern, which is formed by using a pulsed light source that emits light in a pulsed manner and has a relatively short emission time. The present invention is suitable for a semiconductor device manufacturing apparatus in which the irradiation light amount of a surface to be irradiated is controlled with high accuracy when irradiating an existing mask, reticle surface, or the like (hereinafter collectively referred to as “reticle”).

[0002]

2. Description of the Related Art In recent semiconductor device manufacturing technology, a lithographic technology capable of forming a high-density electronic circuit pattern is required as the electronic circuit pattern is highly integrated.

Generally, in order to obtain a high-density semiconductor device by transferring an electronic circuit pattern on the reticle surface to obtain a high-density semiconductor device, the irradiation light amount on the reticle surface, that is, the irradiation light amount on the wafer surface is appropriately controlled. Is important. In an exposure apparatus for manufacturing a semiconductor device, a pulsed light source such as an excimer laser that emits a pulse is used as a light source for illuminating a reticle surface because of its high brightness and good monochromaticity.

The following method is used to control the irradiation light amount (exposure amount) on the surface to be irradiated in an exposure apparatus using a conventional pulse light source. First, the light amount of each pulse is measured and integrated during the integrated exposure, and when it is determined that the target exposure amount is reached with the exposure amount of 1 pulse or less, the light emission of the light source is stopped, and the exposure measured up to that point The underexposure amount is calculated from the integrated value of the amounts. Then, an interference filter is inserted in the optical path, the interference filter is rotated by the driving means to an angle at which a light amount equivalent to the insufficient exposure amount is transmitted, and then one pulse is emitted from the pulse light source, whereby the target exposure amount is obtained. Is getting

[0005]

In the conventional exposure apparatus, an interference filter was used to control the exposure amount on the surface to be illuminated, and the interference filter was rotated in the optical path. A motor is used as a power means for rotating the interference filter. However, generally, it takes time for the motor to rise, so it takes 10 msec or more to rotate the interference filter to a predetermined position. Therefore, the higher the oscillation frequency of the pulse light source and the smaller the total exposure pulse number, the larger the ratio of the motor start-up time to the exposure time, resulting in a decrease in throughput. .

Generally, the control range of the transmittance using an interference filter is about 5 to 90%, 0 to 5%, 90 to
It is very difficult to control the light amount within the range of 100%. Therefore, when the total exposure pulse number is small, the accuracy of the light amount control of the last one pulse has a great influence on the accuracy of the overall exposure amount control, and the accuracy of the exposure amount is deteriorated. There was a problem.

According to the present invention, when irradiating a surface to be irradiated with pulsed light from a pulsed light source that emits pulsed light, the amount of light to be irradiated onto the surface to be irradiated is highly accurate by using an appropriately set transmitted light amount control means. It is an object of the present invention to provide an irradiation light amount control device and a light exposure device using the same, which can be controlled in accordance with the present invention and can easily obtain a highly integrated semiconductor device when applied to an exposure device for manufacturing a semiconductor device.

[0008]

The irradiation light quantity control device of the present invention is (1-1) irradiating the irradiation target surface by monitoring means when the irradiation target surface is cumulatively irradiated with pulsed light from a light source emitting pulsed light. The integrated irradiation light amount is detected, and when the central control means determines that the irradiation light quantity reaches a preset irradiation light quantity by the last one pulse based on the signal from the monitoring means, it has a predetermined reflectance finesse and is in the optical path. The irradiation of the last one pulse on the surface to be irradiated is adjusted by changing the interval of the etalon provided in the piezo element and adjusting the transmittance by the transmitted light amount control means for controlling the transmittance of the etalon. The feature is that the amount of light is controlled.

In particular, the voltage applied to the piezo element is controlled by utilizing the data from the storage means in which the relationship between the voltage applied to the piezo element and the transmittance of the etalon is previously obtained and stored. The transmittance of the etalon is changed, or an interferometer for detecting a change in the interval of the etalon is used by using interference, and the interferometer has a wavelength different from the oscillation wavelength of the pulsed light from the light source. It is characterized in that it uses laser light that emits the above light.

The exposure apparatus of the present invention (1-2) monitors when the pattern on the first object surface is cumulatively irradiated with the pulsed light from the light source which emits the pulsed light, and the pattern is exposed and transferred to the second object surface. Means for detecting the integrated irradiation light amount applied to the first object surface, and based on a signal from the monitoring means, when the central control means determines that the irradiation light amount preset by the last one pulse is reached, a predetermined value is determined. The last one pulse having a reflectance finesse, the transmittance of the etalon adjusted by changing the interval of the etalon provided in the optical path by a piezo element and controlling the transmittance of the etalon. It is characterized in that the irradiation light amount on the first object surface is controlled.

Particularly, the voltage applied to the piezo element is controlled by utilizing the data from the storage means in which the relationship between the voltage applied to the piezo element and the transmittance of the etalon is obtained and stored in advance. The transmittance of the etalon is changed, or an interferometer for detecting a change in the interval of the etalon is used by using interference, and the interferometer has a wavelength different from the oscillation wavelength of the pulsed light from the light source. It is characterized in that it uses laser light that emits the above light.

[0012]

1 is a block diagram of essential parts of a first embodiment when the present invention is applied to a reduction projection type exposure apparatus for semiconductor manufacturing.

In FIG. 1, reference numeral 1 denotes a pulse light source which emits a pulsed light having a good directivity, and is composed of, for example, an excimer laser. Reference numeral 2 denotes a transmitted light amount control means, which has a configuration shown in FIG. 2 described later and controls the transmitted light amount of the light flux from the pulse light source 1. A drive control unit 3 controls the transmittance of the transmitted light amount control unit 2 based on a signal from a central processing unit 4 described later. Reference numeral 4 denotes a central control means, which controls driving of the pulse light source 1 and the drive control means 3.

An illumination optical system 5 has means for making coherent light into incoherent light. The light flux from the transmitted light amount control means 2 is made into incoherent light and a semi-transmissive surface or a transmissive surface is provided in part. The illuminated surface 8 as the first object plane such as a reticle is illuminated through the mirror 6. Reference numeral 7 denotes a monitoring means, which measures the amount of transmitted light that has passed through a part of the mirror 6 to obtain the amount of irradiation light on the surface 8 to be irradiated. A projection optical system 10 reduces and projects the electronic circuit pattern on the illuminated surface 8 onto the wafer 9 surface as the second object surface.

In the present embodiment, in the case of a contact type or proximity type semiconductor manufacturing exposure apparatus, the projection optical system 10 is not necessary, and the mask, which is the surface 8 to be irradiated, and the wafer 9 are in close contact with each other or a slight space is left therebetween. Are arranged. 1
Reference numeral 1 is an optical axis of an optical path of the pulsed light emitted from the pulsed light source 1 to the irradiation surface 8.

Next, the structure of the transmitted light amount control means 2 of this embodiment will be described with reference to FIG.

In FIG. 2, the flat substrates 21a and 21b constitute an etalon 21, and the inner surface thereof has a reflectance of 80.
% Semipermeable membrane, and the outer surface is coated with an antireflection coating. Reference numeral 22 denotes a piezo element, which changes the distance between the flat substrates 21a and 21b. Reference numeral 23 is a support rod that fixes the piezo element 21 to the cover. A leaf spring 24 prevents the piezo element 21 from moving in a direction perpendicular to the expansion / contraction direction. 25 is a cover.

FIG. 3 shows the relationship between the voltage V applied to the piezo element 21 and the transmittance T of the etalon when the reflectance of the semi-permeable film formed on the inner surface of the etalon 21 of FIG. 2 is 80%. It is the explanatory view shown. Transmitted light amount control means 2 of this embodiment
Changes the distance between the flat substrate 21a and the etalon 21b by the flat substrate to the piezo element 21 as shown in FIG.
Thereby, the transmittance of the etalon 21 is controlled variously.

Next, the operation of FIG. 1 will be described. The coherent pulsed light oscillated from the pulse light source 1 composed of an excimer laser is controlled by the light amount control means 2 in the amount of passing light. The light amount control means 2 is driven by a drive command signal from the drive control means 3 to change the distance between the flat substrate 21a and the flat substrate 21b shown in FIG. 2 to control the transmittance of the etalon 21.

Then, the light passing through the light quantity control means 2 is made into incoherent light by the illumination optical system 5, and the circuit pattern of the reticle 8 as the surface to be irradiated is irradiated through the reflecting mirror 6. Then, the circuit pattern on the reticle 8 is reduced and projected onto the surface of the wafer 9 by the projection optical system 10. Then, the semiconductor element is manufactured from the wafer 9 on which the pattern is transferred, through a known developing process.

In this embodiment, the exposed surface 9 is exposed with a predetermined exposure amount as follows. First, the monitoring means 7 detects the pulsed light that has passed through a part of the mirror 6, and measures the amount of each pulsed light emitted by the excimer laser 1 (the amount corresponding to the actual exposure amount on the wafer 9). Is going. Then, the central processing unit 4 obtains the integrated value and the average value of the exposure amount from the signal from the monitoring unit 7.

When the central controller 4 judges that the required integrated exposure amount is reached with the exposure energy of one pulse or less during the exposure of the wafer 9, the insufficient light amount at that time is calculated. Then, the central processing means 4 inputs the result to the drive control means 3.
The piezo element shown in FIG. 2 is driven so that the light amount equivalent to the insufficient light amount passes through based on the signal from
The etalon spacing is changing.

Since the operating time of the etalon is 1 msec or less, it is not necessary to stop the light emission if the pulse light source has an oscillation frequency of about 1 kHz. After the adjustment of the etalon interval is completed, the excimer laser 1 is pulsed. It emits light to complete the exposure.

FIG. 4 is a flowchart for giving an appropriate exposure amount on the surface of the wafer 9 in this embodiment.

In the flow chart of FIG. 4, in step 101, an appropriate exposure amount (appropriate irradiation light amount) A necessary for printing the pattern of the reticle 8 on the wafer 9 on the projection surface, and the excimer laser 1 emits light 1. The exposure amount C on the wafer 9 by the pulse is determined and input to the central processing means 4. In step 102, the excimer laser 1 is set to 1
Pulse light emission is performed, and exposure of the wafer 9 is started.

In step 103, the light quantity of one pulse is measured by the monitoring means 7, and the central control means 4 calculates the integrated value B of the measured values and the actual exposure average value C _ave per pulse. In step 104, when the difference between the proper exposure amount A and the integrated value B is equal to or larger than the actual exposure average value C _ave in the central control means 4, the process returns to step 102 to continue pulse emission.
If it goes down, a judgment is made to go to step 105.

In step 105, the transmittance of the etalon 21 is (A−B) / C _ave × from the relationship between the voltage V applied to the piezo element 22 and the transmittance T of the etalon 21 in FIG.
The central control means 4 calculates the applied voltage to the piezo element 22 which becomes 100 (%), and sends a drive command signal for the piezo element 22 to the drive control means 3. The drive control means 3 is the central control means 4
The piezo element 22 is driven on the basis of the signal from to change the interval of the etalon 21.

In step 106, the excimer laser 1 emits one pulse. In step 107, the light quantity of one pulse is measured by the monitoring means 7, and the integrated value B _{fin of the} measured values is measured.
Is stored by the central control means 4. At step 108, proper exposure on the surface of the wafer 9 is completed.

As described above, in this embodiment, when the etalon is inserted in the optical path and the amount of light is controlled by changing the interval of the etalon with the piezo element, the operation time of the piezo is longer than the rising time of the motor. 1 ms, which is 1/10 or less
The operation is completed when ec or less. The reflectance of the inner reflection surface of the etalon is set to 80%, and the transmittance can be controlled to 1 to 100% by changing the interval of the etalon by 1/4 wavelength.

As described above, in this embodiment, by using the etalon whose reflectance finesse is appropriately set and the piezo element, it is possible to perform the exposure amount control in a shorter time than the conventional one, and at the end. It is possible to adjust the light amount control of one pulse of 1 to 100%.

FIGS. 5 and 6 are schematic views of the essential portions of the transmitted light amount control means in the second and third embodiments of the present invention. The basic configuration of the apparatus in Examples 2 and 3 is the same as that in FIG.

The second embodiment of FIG. 5 is different from the first embodiment of FIG. 2 in that an interferometer 26 is added to detect the distance between the flat substrates 21a and 21b, so that the distance between the flat substrates 21a and 21b is changed. The difference is that it is detected, and other configurations are the same. That is, in this embodiment, the flat substrates 21a and 21a
Example 1 is performed by controlling the amount of light transmitted through the etalon using the relationship between the distance L from b and the transmittance T of the etalon.
Has the same effect as.

FIG. 7 shows the etalon interval L and the etalon transmittance, where L0 is the etalon interval when the transmittance is 100% and L1 is the etalon interval when the transmittance is 1% in this embodiment. The relationship of T is shown. The difference between the distance L1 and the distance L0 is ¼ wavelength.

The third embodiment of FIG. 6 is different from the first embodiment of FIG. 1 in that a laser 27 having a wavelength different from that of the pulse light source 1 and a laser light receiving portion 28 are added, and the other configurations are the same. Is. The laser light from the laser 27 passes through the etalon 21 and is received by the laser light receiver 28. Then, the transmittance of the light flux from the laser 27 with respect to the wavelength is measured. By this, by using the relationship between the transmittance Tr of the etalon 21 with respect to the wavelength of the light flux from the laser 27 and the transmittance T of the etalon 21 with respect to the wavelength of the pulsed light of the pulse light source 1, the amount of light transmitted through the etalon 21 is controlled. The same effect as in Example 1 is obtained.

In this embodiment, for example, KrF is used as the pulse light source.
Excimer laser (wavelength λ ₁ = 248.4 nm), laser 27 is a He-Ne laser (wavelength λ ₂ = 632.8 nm)
Are used respectively. And of λ _1/2 m double and λ ₂ /
When the condition that n times 2 (m and n are integers) coincide with the etalon interval is satisfied, the laser 27 as shown in FIG.
The transmittance T with respect to the wavelength of the pulsed light from the pulse light source 1 is uniquely determined from the transmittance Tr with respect to the wavelength of the light emitted from the etalon, and this embodiment is used to control the transmittance of the etalon.

[0036]

As described above, according to the present invention, when the irradiation surface is irradiated with the pulsed light from the pulsed light source that emits the pulsed light, the irradiation light is controlled by using the appropriately set transmitted light amount control means. Irradiation light amount control device capable of controlling the irradiation light amount onto a surface with high precision and easily obtaining a highly integrated semiconductor device when applied to an exposure device for manufacturing a semiconductor device, and an exposure device using the same Can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment when the present invention is applied to a reduction projection type exposure apparatus for manufacturing a semiconductor device.

FIG. 2 is a schematic diagram of a transmitted light amount control means of FIG.

3 is an explanatory diagram showing the relationship between the applied voltage V to the piezo element of FIG. 2 and the transmittance T of the etalon.

FIG. 4 is a flowchart of the operation of the first embodiment.

FIG. 5 is a schematic diagram of transmitted light amount control means according to a second embodiment of the present invention.

FIG. 6 is a schematic diagram of transmitted light amount control means according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram showing the relationship between the etalon interval L and the etalon transmittance T in the transmitted light amount control means according to the second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a relationship between an etalon and a transmittance Tr for a laser light having a different wavelength from a pulse light source and a transmittance Tr of the etalon for a laser light of the pulse light source in the transmitted light amount control means according to the second embodiment of the present invention.

[Explanation of symbols]

 1 Pulsed Light Source 2 Transmitted Light Amount Control Means 3 Drive Control Means 4 Central Control Means 5 Illumination Optical System 6 Mirror 7 Monitoring Means 8 Irradiated Surface 9 Wafer 10 Projection Optical System

Claims (8)

[Claims] 1. When cumulatively irradiating a surface to be illuminated with pulsed light from a light source that emits pulsed light, monitoring means detects the cumulative amount of irradiation light that is irradiated onto the surface to be illuminated, and based on a signal from the monitoring means. When it is judged by the central control means that the irradiation light amount set in advance by the last one pulse is reached, it has a predetermined reflectance finesse, and the interval of the etalon provided in the optical path is changed by the piezo element to transmit the etalon. An irradiation light quantity control device, characterized in that the transmittance is adjusted by a transmitted light quantity control means for controlling the rate to control the irradiation light quantity of the last one pulse onto the surface to be irradiated. 2. The voltage applied to the piezo element is controlled by utilizing the data from the storage means in which the relationship between the voltage applied to the piezo element and the transmittance of the etalon is obtained and stored in advance. 2. The irradiation light amount control device according to claim 1, wherein the transmittance of is changed. 3. An interferometer for detecting a change in the distance between the etalons by using interference.
Irradiation light amount control device. 4. The irradiation light amount control device according to claim 3, wherein the interferometer uses laser light that emits light having a wavelength different from the oscillation wavelength of the pulsed light from the light source. 5. A pattern on the first object surface is cumulatively irradiated with pulsed light from a light source that emits pulsed light, and the pattern is secondarily irradiated.
When the exposure transfer is performed on the object surface, the monitoring means detects the integrated irradiation light amount irradiated to the first object surface, and the central control means based on the signal from the monitoring means, the irradiation light amount preset in the last one pulse. When it is determined that the etalon is reached, it has a predetermined finesse of the reflectance, the interval of the etalon provided in the optical path is changed by the piezo element, and the transmitted light amount control means for controlling the transmittance of the etalon is transmitted. An exposure apparatus, wherein the exposure light amount of the last one pulse on the first object surface is controlled by adjusting the rate. 6. The voltage applied to the piezo element is controlled by utilizing the data from the storage means in which the relationship between the voltage applied to the piezo element and the transmittance of the etalon is obtained and stored in advance. 6. The exposure apparatus according to claim 5, wherein the transmittance of the exposure device is changed. 7. An interferometer for detecting a change in the interval of the etalon using interference is provided.
Exposure equipment. 8. The exposure apparatus according to claim 7, wherein the interferometer uses laser light that emits light having a wavelength different from the oscillation wavelength of the pulsed light from the light source.