CN212435019U - Device for broadening high-energy excimer laser pulse - Google Patents
Device for broadening high-energy excimer laser pulse Download PDFInfo
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- CN212435019U CN212435019U CN202021893101.3U CN202021893101U CN212435019U CN 212435019 U CN212435019 U CN 212435019U CN 202021893101 U CN202021893101 U CN 202021893101U CN 212435019 U CN212435019 U CN 212435019U
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Abstract
The utility model discloses a device for high energy excimer laser pulse widens, it is eight or when sixteen to have made clear the number of the spherical reflector that constitutes the optics delay chamber, and the light beam characteristic of output beam can be controlled to the pulse widening device when effectively widening excimer laser pulse width, through the radius of curvature of speculum in the optimization pulse widening device, guarantees that the output beam characteristic parameter of light beam after pulse widening device widens does not change, has actual engineering using value; the pulse widening device effectively widens the pulse width of the excimer laser and controls the beam characteristics of the output beam at the same time, ensures that the beam characteristic parameters of the input beam and the output beam are not changed by optimizing the curvature radius of the reflector, and has practical engineering application value.
Description
Technical Field
The utility model relates to an aim at the technical field that molecule laser instrument output parameter carries out regulation and control, concretely relates to a device that is used for high energy excimer laser pulse to widen.
Background
The progress of the lithography technology promotes the great development of the large-scale integrated circuit manufacturing process, with the continuous promotion of the lithography technology node, the wavelength of the exposure light source used by the lithography machine is from 436nm (G line), 365nm (I line), to 248nm (KrF excimer laser), 193nm (ArF excimer laser) and then to 10-14nm of extreme ultraviolet wavelength (EUV), and the exposure light source of the lithography machine of the technology node of 45nm to 10/7nm which is widely used at present is 193nm ArF excimer laser. In order to improve the production efficiency of a photoetching machine, the output energy of an excimer laser for photoetching is continuously improved, but at the same time, the output energy also brings risks to an optical system of the photoetching machine, a large number of expensive deep ultraviolet calcium fluoride and fused quartz optical elements are used in an illumination and exposure optical system of the photoetching machine, and color centers and other physical or chemical processes can be generated in the material of the deep ultraviolet optical elements under the long-time irradiation of the deep ultraviolet laser with the wavelength of 193nm, so that the optical performance of the deep ultraviolet optical elements is slowly reduced until catastrophic damage occurs, and the service life of the optical elements is finished. Studies have shown that the degradation rate of these optical elements is closely related to the peak power of the laser pulse (P ═ E/τ, P is the peak power, E is the pulse energy, τ is the pulse width), and the higher the peak power, the faster the optical element degrades and the shorter the lifetime. In order to improve the output pulse energy of the excimer laser for photoetching and not shorten the service life of an optical element, an excimer laser pulse stretching device can be used for stretching the output laser pulse of the excimer laser, so that the peak power of the laser pulse is reduced.
At present, pulse stretching devices for excimer lasers in the market are mainly produced by American Cymer company, and a single excimer laser pulse stretching device consisting of a single beam splitting element and a plurality of spherical reflectors is adopted or two pulse stretching devices are connected in series for use. In order to further improve the pulse stretching efficiency and improve the output pulse waveform, domestic research and study has proposed an excimer laser pulse stretching device based on a dual beam-splitting element and a plurality of spherical mirrors. For example, chinese patent No. CN104319615B, "an excimer laser pulse stretching device based on a dual beam splitting element," discloses a pulse stretching device based on a dual beam splitting element and a confocal resonant cavity composed of two or four spherical mirrors, and by increasing the length of the resonant cavity, the stretching ratio of the single-stage pulse stretching device can be increased to more than four times. Chinese patent application No. CN109672079, "a method and apparatus for broadening quasi-molecule laser pulse based on two-stage series connection," adopts a former-stage pulse broadening apparatus based on a confocal resonant cavity composed of a single beam splitting element and a plurality of spherical reflectors, and a latter-stage pulse broadening apparatus based on a confocal resonant cavity composed of a double beam splitting element and a plurality of spherical reflectors, to constitute a magnitude series pulse broadening apparatus, which can further improve the broadening ratio of quasi-molecule laser pulse. The above patent has the disadvantages that how to ensure that the characteristics of the light beam do not change after the light beam passes through the pulse stretching device is not considered, if the characteristics of the light beam stretched by the pulse stretching device change greatly, errors and control difficulties are generated in the subsequent processing and application of the optical system of the photoetching machine for the stretched light beam, the exposure performance and the product quality of the photoetching machine are influenced, and the actual use effect of the pulse stretching device is limited.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a device that is used for high energy excimer laser pulse to widen based on the optics delay cavity that two beam splitting components and eight spherical mirror are constituteed is direct, when can effectively widen excimer laser pulse width, guarantees that the laser beam is through the beam characteristics of pulse widening device optics delay output and the direct beam characteristics through pulse widening device unanimous completely.
The utility model discloses a following technical scheme realizes:
the scheme provides a device for broadening high-energy excimer laser pulses, which comprises a pulse broadening device directly formed by an optical delay cavity consisting of two beam splitting elements and eight spherical reflectors, or comprises a preceding-stage pulse broadening device formed by the optical delay cavity consisting of the two beam splitting elements and the eight spherical reflectors and a subsequent-stage pulse broadening device formed by the optical delay cavity consisting of a single beam splitting element and a plurality of spherical reflectors;
the incident beam is subjected to optical delay through the pulse stretching device or the preceding stage pulse stretching device, and is output as an erect image after being subjected to even-number reflection of the beam splitting element and the spherical reflector and even-number imaging of the spherical reflector;
and controlling the curvature radius of the spherical reflector to ensure that the beam characteristic parameters of the output beam after optical delay are completely consistent with the beam characteristic parameters of the output beam after the output beam is directly transmitted by the beam splitting element at the output port of the pulse broadening device. Thereby ensuring that the beam characteristic parameters of the output beam are not altered by pulse broadening.
In a further preferred embodiment, the number of spherical mirrors in the pulse widening apparatus based on two beam splitting elements and eight spherical mirrors forming an optical delay cavity can also be increased to sixteen, but the number must be an integer multiple of eight and at most sixteen.
The further optimization proposal is that the pulse stretching device based on the optical delay cavity composed of two beam splitting elements and eight spherical mirrors,
the first beam splitting element splits an incident beam into two beams, one beam enters the optical delay cavity to generate certain optical delay and then enters the second beam splitting element, and the other beam directly enters the second beam splitting element; by optimizing the curvature radius of the spherical reflector, the beam characteristic parameters of the two beams of light which are incident to the second beam splitting element through the two paths are kept completely consistent;
the second beam splitting element further splits each incident beam into two beams, wherein one beam is directly output, and the other beam enters the optical delay cavity to generate certain optical delay and then returns to the first beam splitting element for further beam splitting; by optimizing the curvature radius of the spherical reflector, simultaneously, imaging conjugate points formed by input light beams in the transmission process of the delay cavity are the position of a first beam splitting element and the position A in front of a second beam splitting element, and the distance from the position A to the second beam splitting element is equal to the distance between the two beam splitting elements; the characteristic parameters of the light beam returning to the first beam splitting element after optical delay are completely consistent with the characteristic parameters of the incident light beam entering the pulse broadening device;
the above process is repeated until the energy of the laser beam after multiple beam splitting is negligibly low.
Thereby eliminating the problem of different beam characteristic parameters of the laser beam passing through the optical delay cavity and the direct output beam due to the adoption of two beam splitting elements.
Further optimization scheme is that the beam characteristic parameters include: beam divergence angle, beam directivity drift characteristics, and spot size.
The further optimization scheme is that the curvature radius of the spherical reflector is related to the length of the optical delay cavity.
The further optimization scheme is that when the curvature radius of the spherical reflector is optimized, the condition that the focusing position of a light beam is close to the optical element needs to be avoided, and the optical element is ensured not to generate laser damage.
The utility model also provides a method for high energy excimer laser pulse widens, including following step:
t1, the incident beam is subjected to optical delay through the pulse broadening device, and is output as a positive image after being subjected to even-number reflection of the beam splitting element and the spherical reflector and even-number imaging of the spherical reflector;
and T2, controlling the curvature radius of the spherical reflector to ensure that the light beam characteristic parameters of the output light beam after optical delay are completely consistent with the light beam characteristic parameters of the output light beam directly transmitted by the pulse stretching device at the output port of the pulse stretching device.
The pulse stretching device is a pulse stretching device directly formed by an optical delay cavity consisting of two beam splitting elements and eight spherical reflectors, or a preceding stage pulse stretching device formed by an optical delay cavity consisting of two beam splitting elements and eight spherical reflectors and a subsequent stage pulse stretching device formed by an optical delay cavity consisting of a single beam splitting element and a plurality of spherical reflectors.
The utility model discloses the theory of operation: the pulse stretching device for the excimer laser in the market does not consider how to ensure that the characteristics of the light beam do not change after the light beam passes through the pulse stretching device, if the characteristics of the light beam stretched by the pulse stretching device change greatly, errors and control difficulty are generated in the subsequent treatment and application of the stretched light beam in an optical system of a photoetching machine, the exposure performance and the product quality of the photoetching machine are influenced, and the actual use effect of the pulse stretching device is limited; the pulse widening device directly formed by the optical delay cavity formed by the two beam splitting elements and the eight spherical reflectors provided by the utility model has the advantages that each output light beam after different optical delays is reflected by the beam splitting elements and the spherical reflectors for even number of times, and even-numbered imaging of the spherical reflector, the delayed light beams are all imaged and output in a positive mode, the directivity drift characteristic of the output light beam is ensured to be completely consistent with the directivity drift characteristic of the input light beam, thereby ensuring that the directivity drift characteristic and the divergence angle of the output light beam are not changed due to pulse broadening, controlling the curvature radius of the spherical reflector, the divergence angle, the directivity drift characteristic, the spot size and other light beam characteristic parameters of the output light beam after optical delay are completely consistent with the light beam characteristic parameters of the output light beam directly transmitted by the beam splitting element at the output port of the pulse broadening device.
Compared with the prior art, the utility model, following advantage and beneficial effect have: the utility model provides a pair of excimer laser pulse widening device based on optical delay chamber is constituteed to two beam splitting components and eight spherical reflectors, it is eight or sixteen to have made clear the number of spherical reflectors forming optical delay chamber, pulse widening device can be in the effective beam characteristic of controlling output beam when widening excimer laser pulse width, through the radius of curvature of optimizing pulse widening device middle reflector, guarantee that the output beam characteristic parameter of light beam after pulse widening device widens does not change, the engineering that has reality is worth.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention.
FIG. 1 is a schematic diagram of an excimer laser pulse stretching apparatus structure and a light beam transmission path based on an optical delay cavity composed of two beam splitting elements and an eight-spherical mirror;
FIG. 2 is a schematic structural diagram of a two-stage pulse stretching device with a front stage pulse stretching device and a rear stage pulse stretching device;
FIG. 3 is a schematic diagram of an excimer laser pulse stretching apparatus structure and a partial light beam transmission path based on an optical delay cavity composed of two beam splitting elements and four spherical mirrors;
fig. 4 is a schematic diagram of an excimer laser pulse stretching device structure and a partial beam transmission path based on an optical delay cavity composed of two beam splitting elements and a six-spherical mirror.
Detailed Description
To make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following examples and drawings, and the exemplary embodiments and descriptions thereof of the present invention are only used for explaining the present invention, and are not intended as limitations of the present invention.
Example 1
As shown in fig. 1, the excimer laser pulse stretching apparatus based on an optical delay cavity formed by two beam splitting elements and eight spherical mirrors adopted in this embodiment is composed of a first beam splitting element BS1, a second beam splitting element BS2 (both the first beam splitting element BS1 and the second beam splitting element BS2 are 45-degree beam splitting elements), a spherical mirror M1, a spherical mirror M2, a spherical mirror M3, a spherical mirror M4, a spherical mirror M5, a spherical mirror M6, a spherical mirror M7, and a spherical mirror M8.
The input light beam is first split into two beams, a transmitted beam and a reflected beam, by a first beam splitting element BS 1. The transmitted light beam directly enters the second beam splitting element BS2 to be further split, the reflected light beam is reflected by the spherical mirrors M1, M2, M3 and M4 to be delayed in optical mode and then enters the second beam splitting element BS2 to be further split, the light beam entering the second beam splitting element BS2 is split into two light beams, one light beam is directly output, and the other light beam returns to the first beam splitting element BS1 to be further split after being delayed in optical mode by the spherical mirrors M5, M6, M7 and M8.
A part of light beams in the input light beams are reflected by the first beam splitting element BS1, the spherical mirror M1, the spherical mirror M2, the spherical mirror M3, the spherical mirror M4 and the second beam splitting element BS2, and output light beams formed by even-number (six-time) mirror reflection and even-number imaging (twice) are imaged to form an erect image, so that the directivity drift characteristics of the output light beams after reflection delay are completely consistent with the input light beams, and the divergence angle and the beam drift directivity characteristics of the output light beams after pulse broadening are completely consistent with the input light beams. In addition, by optimizing the curvature radii of the spherical mirror M1, the spherical mirror M2, the spherical mirror M3 and the spherical mirror M4, the characteristic parameters of the output light beam and the light beam output after the input light beam directly passes through the first beam splitting element BS1 and the second beam splitting element BS2, such as the spot size, the beam divergence angle and the light beam stability, are kept consistent. Considering the beam divergence angle and the distance between the first and second beam splitting elements BS1, BS2, the spot size of the output beam at the second beam splitting element BS2 is larger than the spot size of the input beam at the first beam splitting element BS1, but the beam divergence angle and the beam directivity remain unchanged.
The imaging conjugate point formed by the input beam during the propagation of the delay cavity is the screen at the position point of the first beam splitting element BS1 and the position point a above the second beam splitting element BS2, and the distance between the position point a and the second beam splitting element BS2 is equal to the distance between the first beam splitting element BS1 and the second beam splitting element BS 2. The light beam returned to the delay cavity by the second beam splitting element BS2 is reflected by the spherical mirror M5, the spherical mirror M6, the spherical mirror M7 and the spherical mirror M8 and then returned to the first beam splitting element BS1, so that the final output light beam of the reflected light beam part is consistent with the characteristic parameters of the spot size, the beam divergence angle, the beam drift and the like of the input light beam by optimizing the curvature radii of the spherical mirror M5, the spherical mirror M6, the spherical mirror M7 and the spherical mirror M8, and the position point a and the position point of the first beam splitting element BS1 are still imaging conjugate points.
Example 2
In order to further improve pulse broadening ratio, will the utility model discloses an based on two beam splitting components, eight spherical surface mirrors constitute the excimer laser pulse broadening device of optical delay chamber and based on single beam splitting component, the excimer laser pulse broadening device of optical delay chamber is constituteed to four spherical surface mirrors establishes ties and uses, as shown in fig. 2, output beam and the input beam through optical delay chamber directly see through beam splitting component BS1, beam splitting component BS2, the spot size of the light beam of beam splitting component BS3 output, beam divergence angle and beam drift characteristic parameter keep unanimous.
The curvature radius of the spherical mirror in the excimer laser pulse broadening device adopted in the embodiment is related to the length of the optical delay cavity, and when the curvature radius of the spherical mirror is optimized, the condition that the focusing position of a light beam is close to an optical element needs to be avoided.
Example 3
To further illustrate the necessity of the number of mirrors being 8 in the optical delay cavity, fig. 3 illustrates an excimer laser pulse broadening device which uses an optical delay cavity composed of two beam splitting elements and four spherical mirrors, wherein a part of the input beam is reflected by the beam splitting element BS4, the spherical mirror M13, the spherical mirror M14 and the beam splitting element BS5, and after even (four) times of mirror reflection and odd (one) times of imaging, the formed output beam and the input beam are inverted, resulting in a final output beam including two beams of positive and inverted images, and when the input beam is shifted in pointing direction, the directional shift of the output beam is multiplied, resulting in a poor pointing stability of the input beam after passing through the excimer laser pulse broadening device.
Similarly, fig. 4 shows an excimer laser pulse broadening device including two beam splitting elements and six spherical mirrors, a part of light beams in an input light beam is reflected by the beam splitting element BS6, the spherical mirror M17, the spherical mirror M18, the spherical mirror M19, the beam splitting element BS7, and after odd (five) times of mirror reflection and even (two) times of imaging, the formed output light beam and the input light beam are inverted, so that the final output light beam includes two kinds of light beams that are imaged in an erect or inverted manner.
The above-mentioned embodiments, further detailed description of the objects, technical solutions and advantages of the present invention, it should be understood that the above description is only the embodiments of the present invention, and is not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. A device for broadening high-energy excimer laser pulse is characterized by comprising a pulse broadening device directly formed by an optical delay cavity consisting of two beam splitting elements and eight spherical reflectors, or comprising a preceding-stage pulse broadening device formed by the optical delay cavity consisting of the two beam splitting elements and the eight spherical reflectors and a subsequent-stage pulse broadening device formed by the optical delay cavity consisting of a single beam splitting element and a plurality of spherical reflectors;
the incident beam is subjected to optical delay through the pulse stretching device or the preceding stage pulse stretching device, and is output as an erect image after being subjected to even-number reflection of the beam splitting element and the spherical reflector and even-number imaging of the spherical reflector;
and controlling the curvature radius of the spherical reflector to ensure that the beam characteristic parameters of the output beam after optical delay are completely consistent with the beam characteristic parameters of the output beam after the output beam is directly transmitted by the beam splitting element at the output port of the pulse broadening device.
2. The apparatus of claim 1, wherein the number of spherical mirrors in the pulse widening apparatus based on the optical delay cavity composed of two beam splitting elements and eight spherical mirrors can be increased to sixteen, but the number must be an integral multiple of eight and at most sixteen.
3. The device of claim 1, wherein the pulse stretching device based on two beam splitting elements and eight spherical mirrors to form an optical delay cavity,
the first beam splitting element splits an incident beam into two beams, one beam enters the optical delay cavity to generate optical delay and then enters the second beam splitting element, and the other beam directly enters the second beam splitting element; by optimizing the curvature radius of the spherical reflector, the beam characteristic parameters of the two beams of light which are incident to the second beam splitting element through the two paths are kept completely consistent;
the second beam splitting element further splits each incident beam into two beams, wherein one beam is directly output, and the other beam enters the optical delay cavity to generate optical delay and then returns to the first beam splitting element for further beam splitting; by optimizing the curvature radius of the spherical reflector, the characteristic parameters of the light beam returning to the first beam splitting element after optical delay and the light beam of the incident light beam entering the pulse broadening device are kept completely consistent;
the above process is repeated until the energy of the laser beam after multiple beam splitting is negligibly low.
4. The apparatus of claim 3, wherein the pulse spreading unit is configured to spread the high-energy excimer laser pulse,
by optimizing the curvature radius of the spherical mirror, the imaging conjugate point formed by the input light beam in the transmission process of the optical delay cavity is the position of the first beam splitting element and the position A in front of the second beam splitting element, and the distance from the position A to the second beam splitting element is equal to the distance between the two beam splitting elements.
5. The apparatus of claim 3, wherein the beam characteristic parameters comprise: beam divergence angle, beam directivity drift characteristics, and spot size.
6. The apparatus according to claim 3 or 4, wherein the radius of curvature of the spherical mirror is related to the length of the optical delay cavity.
7. The apparatus of claim 3, wherein the radius of curvature of the spherical mirror is optimized while avoiding the beam focusing position near the optical element to ensure that the optical element does not generate laser damage.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111969395A (en) * | 2020-09-02 | 2020-11-20 | 成都技致光电科技有限公司 | Device and method for broadening high-energy excimer laser pulse |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111969395A (en) * | 2020-09-02 | 2020-11-20 | 成都技致光电科技有限公司 | Device and method for broadening high-energy excimer laser pulse |
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