Ultraviolet light source with minimal coherence factor

Abstract

The invention belongs to the technical field of photoetching light sources, and particularly relates to a minimum coherence factor ultraviolet light source, which comprises an ultraviolet lamp provided with a light-emitting element and a connecting piece which are connected with each other; when the light-emitting element irradiates, a shadow part is formed at one end, far away from the light-emitting element, of the connecting piece; an inlet of the relay lens group collects uniform light of the light-emitting element, and an outlet of the relay lens group is a light outlet of the ultraviolet light source; wherein the uniform light does not contain the shadow part. According to the invention, the relay lens group collects the uniform light of the light emitting source element avoiding the shadow of the connecting piece, avoids the pupil'center missing 'phenomenon, can form perfect small-angle light source illumination, can realize extremely small Sigma (coherence factor) illumination, realizes a full-pupil illumination scheme, meets the imaging, detection and illumination application, and further improves the detection precision and the photoetching image quality.

Description

Technical Field

[0001] The invention belongs to the technical field of photolithography light sources, and in particular relates to an ultraviolet light source with a very small coherence factor. Background Art

[0002] In lithography imaging and detection equipment, an illumination system is often required to provide light source illumination. With the improvement of image quality requirements for lithography imaging systems and the demand for detection capabilities of detection equipment, the requirements for illumination light sources are also increasing. Not only are there certain requirements for illumination intensity, uniformity, and output NA, but there are also requirements for the morphology of the pupil.

[0003] In the field of ultraviolet lighting, the typical light sources are ultraviolet mercury lamps and LED light sources, each with its own characteristics. The spectrum of ultraviolet mercury lamps is thinner and the luminous energy density is higher, while the spectrum of LED light sources is wider and the energy density is relatively lower.

[0004] Mercury lamps generally use an ellipsoidal bowl to collect light energy. Due to the installation and size of the mercury lamp pole, the ellipsoidal reflection bowl of the mercury lamp needs to have a hole in the top of the bowl. This method will cause a lack of small-angle light when the mercury lamp light source is emitted, resulting in a lack of central light energy in the pupil image during subsequent lighting and imaging.

[0005] Fiber optic splitting is also a way of splitting light, but due to the low transmittance of optical fiber, there will be a large loss in success rate. Summary of the invention

[0006] In view of this, the present invention proposes an ultraviolet light source with extremely small coherence factor, which collects uniform light from the light source element to avoid the shadow of the connecting parts, avoids the phenomenon of "lack of center" in the pupil, can form a perfect small-angle light source illumination, can achieve extremely small Sigma (coherence factor) illumination, and realizes a full-pupil illumination solution to meet imaging, detection and lighting applications, thereby improving detection accuracy and lithography image quality.

[0007] In order to achieve the above technical effects, the specific technical solution adopted by the present invention is:

[0008] A very small coherence factor ultraviolet light source, comprising:

[0009] The ultraviolet lamp comprises a light-emitting element and a connecting piece connected to each other; when the light-emitting element irradiates, an end of the connecting piece away from the light-emitting element forms a shadow portion;

[0010] At least one relay mirror group, the entrance of which collects the uniform light of the light-emitting element, and the exit of which is the light outlet of the ultraviolet light source;

[0011] Wherein: the uniform light does not include the shadow part.

[0012] Furthermore, the ultraviolet lamp is a mercury lamp, and the optical axis of the relay lens assembly is perpendicular to a cathode-anode line of the mercury lamp and passes through the center of the cathode-anode line.

[0013] Furthermore, the relay lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence from the object plane to the image plane; the optical path of the relay lens group is symmetrically arranged, and the optical axis passes through the light-emitting element; the radius of curvature of one side of the first lens is ≥300mm, which is used to fully couple and transmit large-angle light; the second lens and the third lens are both biconvex lenses, which are symmetrical about the relay center of the relay lens group; the fourth lens is a biconvex lens, which is used to converge the light of the third lens to the image plane.

[0014] Furthermore, the distance between the second lens and the third lens is ≥40 mm, and the incident angle of the third lens is ≤10°.

[0015] Furthermore, the ultraviolet light source also includes an adjusting reflector; the adjusting reflector is used to reflect the illumination light of the light emitting element at the end of the light emitting element away from the relay lens group, compensate the pupil of the relay lens group, and make the pupil of the relay lens group symmetrical.

[0016] Furthermore, the adjustment reflector is a spherical reflector, the center of which is located at the light-emitting point of the light-emitting element, the diameter of the reflective surface is equal to the incident aperture of the relay lens group, and the vertex-center line coincides with the optical axis of the relay lens group.

[0017] Furthermore, the relay mirror groups are two or more groups, which are arranged on the periphery of the ultraviolet lamp.

[0018] Furthermore, the ultraviolet light source includes N groups of relay mirrors, which are symmetrical about the cathode-anode line of the light-emitting element and arranged annularly on the periphery of the ultraviolet lamp; a reflector is provided on the object surface; wherein: N=1, 2, 3...; the reflector is configured to semi-transmit and semi-reflect the light.

[0019] Furthermore, a pupil baffle is provided between the second lens and the third lens, and the pupil baffle is used to enable the exit port of the relay lens group to form traditional illumination, annular illumination or quadrupole illumination; the pupil baffle is 2-23 mm away from the second lens.

[0020] Furthermore, a filter is provided between the second lens and the third lens; the filter is 2-28 mm away from the second lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a schematic diagram of the structure of a very small coherence factor ultraviolet light source in a specific implementation manner of the present invention;

[0023] Figure 2 Schematic diagram of the light emitting angle distribution of a mercury lamp in a specific embodiment of the present invention;

[0024] Figure 3 It is a pupil diagram of the image plane of the relay mirror group when no adjusting reflector is provided in a specific embodiment of the present invention;

[0025] Figure 4 It is a pupil diagram of the image plane of the relay mirror group when an adjustable reflector is provided in a specific embodiment of the present invention;

[0026] Figure 5 A pupil diagram of the image plane of the relay lens group when a pupil baffle is provided in a specific embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of the structure of a very small coherence factor ultraviolet light source in which a group of ultraviolet lamps is configured with two groups of relay mirrors in a specific embodiment of the present invention;

[0028] Figure 7 It is a schematic diagram of the structure of a very small coherence factor ultraviolet light source in which one set of ultraviolet lamps is configured with four sets of relay mirrors in a specific embodiment of the present invention;

[0029] Figure 8 It is a schematic diagram of the structure of a very small coherence factor ultraviolet light source in which one set of ultraviolet lamps is configured with six sets of relay mirrors in a specific embodiment of the present invention;

[0030] Among them: 1. UV lamp; 2. Relay lens group; 21. First lens; 22. Second lens; 23. Third lens; 24. Fourth lens; 3. Reflector group; 4. Reflector. DETAILED DESCRIPTION

[0031] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0032] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0033] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0034] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The drawings only show components related to the present disclosure rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0035] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0036] Since the light-emitting element of the ultraviolet lamp 1 must be installed through connectors such as power supply lines and mounting structures; the traditional ultraviolet lamp 1 is based on an ellipsoidal reflective bowl to converge and reflect the output light of the light-emitting element, and the connector is set on the ellipsoidal reflective bowl. Since the connector will block the light, the reflected light of the ellipsoidal bowl cannot reflect the light of the light-emitting element to reach the connector and form a shadow. This part of the shadow will increase the coherence factor of the ultraviolet lamp 1, thereby affecting the working performance of the detection optical path and the lithography optical path using the ultraviolet lamp 1.

[0037] The present embodiment provides a very small coherence factor ultraviolet light source, which is intended to eliminate the coherence factor of the ultraviolet lamp 1 to the maximum extent, and includes:

[0038] The ultraviolet lamp 1 comprises a light-emitting element and a connecting piece connected to each other; when the light-emitting element irradiates, a shadow portion is formed at one end of the connecting piece away from the light-emitting element;

[0039] At least one relay lens group 2, the entrance of which collects the uniform light of the light-emitting element, and the exit of which is the light outlet of the ultraviolet light source;

[0040] Wherein: the uniform light does not include the shadow part.

[0041] In this embodiment, the ultraviolet lamp 1 is used for illumination of an optical path system with high requirements on coherence factor for detection, illumination and / or photolithography purposes, which is not limited here.

[0042] The ultraviolet lamp 1 of this embodiment has the characteristic of a narrow single wavelength FWHM, which is ≤10 nm, and the light emitting element is a mercury lamp, etc., which is not limited here.

[0043] The relay lens assembly 2 of this embodiment is used for collecting and transmitting light energy, and the light collection surface avoids the shadow of the connecting member, that is, the connection line between the light emitting element and the connecting member cannot reach the object surface of the relay lens assembly 2. The specific fixing and installation method of the ultraviolet lamp 1 and the relay lens assembly 2 of this embodiment is not limited in this embodiment.

[0044] Since the light collected by the relay lens group 2 in this embodiment avoids the shadow of the connecting part, the collected light is uniform light. The ultraviolet light source in this embodiment has the characteristic of a very small factor, which can improve the optical performance of the detection light path and the lithography light path using the ultraviolet light source in this embodiment, thereby improving the detection accuracy and lithography image quality.

[0045] In one embodiment, the ultraviolet lamp 1 is a mercury lamp, and the optical axis of the relay lens assembly 2 is perpendicular to a cathode-anode connection line of the mercury lamp and passes through the center of the cathode-anode connection line.

[0046] Mercury lamps are widely used in the field of photolithography and are used as light sources for photolithography of mask patterns onto substrates. The working principle is that mercury vapor is ionized and excited to emit light under the action of the cathode and the anode, and the mercury vapor is arranged in the light-emitting tube between the cathode and the anode. In this embodiment, the relay lens group 2 is arranged on the cathode-anode line of the mercury lamp and passes through the center of the cathode-anode line, that is, the optical axis is perpendicular to the light-emitting tube and passes through the center of the light-emitting tube, and light energy is collected on the side of the mercury lamp, which can ensure that light at various angles under a certain NA is filled with energy to meet the subsequent splitting and pupil adjustment requirements.

[0047] In one embodiment, the relay lens group 2 includes a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24 arranged in sequence from the object plane to the image plane; the optical path of the relay lens group 2 is arranged rotationally symmetrically, and the optical axis passes through the energy center of the light-emitting element. The radius of curvature of one side (object plane) of the first lens 21 is ≥300mm, which is used to fully couple and transmit large-angle light; the second lens 22 and the third lens 23 are both biconvex lenses, symmetrical about the relay center of the relay lens group; the fourth lens 24 is a biconvex lens, which is used to converge the light of the third lens 23 to the image plane.

[0048] The distance between the second lens 22 and the third lens 23 is ≥40 mm, and the incident angle of the third lens 23 is ≤10°, which can be used to expand the filter and ensure the filtering effect of the filter.

[0049] In one embodiment, the ultraviolet light source further includes an adjusting reflector; the adjusting reflector is used to reflect the illumination light of the light emitting element at the end of the light emitting element away from the relay lens group 2, to compensate for the pupil of the relay lens group 2, and to make the pupil of the relay lens group 2 symmetrical.

[0050] In this embodiment, the adjustment reflector is a spherical reflector, the center of which is located at the light-emitting point of the light-emitting element, the diameter of the reflective surface is equal to the incident aperture of the relay lens group 2, and the vertex-center line coincides with the optical axis of the relay lens group 2.

[0051] Due to the luminous characteristics of the mercury lamp light source, the angular distribution along the central axis of the mercury lamp is not uniform. Figure 2 , the light emitted from the side is asymmetric along the axis, which will cause the light to deviate to one side and have a telecentric phenomenon, such as Figure 3 In order to compensate for the pupil symmetry problem, a reflector is added in the opposite direction of the optical axis. The reflector type is a spherical reflector. The light point of the mercury lamp is located at the center of the reflector. The reflected light and the original optical fiber are combined to form a new pupil illumination. Figure 4 , the pupil diagram is compared to Figure 3 Pupil diagram, symmetrical from top to bottom.

[0052] In one embodiment, Figure 6-8 As shown, the relay mirror groups 2 are two or more groups, which are arranged circumferentially on the periphery of the ultraviolet lamp 1. In this embodiment, each relay mirror group 2 can be optionally configured with an adjustable reflector; the performance of each relay mirror is set according to the needs, and whether the performance is the same is not limited here. It can achieve two or more lighting channels working independently at the same time, effectively improving the energy utilization rate of the mercury lamp.

[0053] In one embodiment, the ultraviolet light source includes N groups, which are arranged symmetrically in pairs with respect to the cathode-anode connection center of the light-emitting element and are arranged in a circular direction on the periphery of the ultraviolet lamp 1; a reflector 4 is provided on the object surface; wherein: N=1, 2, 3...; the reflector 4 is configured to be semi-transmissive and semi-reflective to light. The relay lens groups 2 of this embodiment are arranged opposite to each other in pairs, and the reflectors 4 can replace the adjustment reflectors of the above-mentioned embodiment. This embodiment can ensure the incident aperture of each relay lens group 2 without affecting the pupil symmetry of each relay lens group 2. When the incident apertures of the relay lens groups 2 that are symmetrical in pairs are the same, and the effective aperture of the reflector 4 is equal to this aperture, the pupil symmetry of each relay lens group 2 can be guaranteed to the maximum extent (such as Figure 7 , 8 shown).

[0054] The reflector 4 of this embodiment is a semi-transparent and semi-reflective film, a semi-transparent and semi-reflective mirror, etc., which is not limited here.

[0055] In one embodiment, a pupil baffle is further provided between the second lens 22 and the third lens 23, and the pupil baffle is used to make the output port of the relay lens group 2 form traditional illumination, annular illumination or quadrupole illumination; the pupil baffle is 2-23 mm away from the second lens 22. The pupil surface of this embodiment is between the second lens 22 and the third lens 23, and the pupil can be adjusted twice on this pupil surface. The annular illumination effect of this embodiment is as follows: Figure 5 shown.

[0056] In this embodiment, if there are two or more relay lens groups 2, different pupil baffles can be configured for the relay lens groups 2 to enable the ultraviolet light source of this embodiment to generate light sources with different requirements, thus having multiple uses.

[0057] In one embodiment, a filter is further disposed between the second lens 22 and the third lens 23; the filter is 2-28 mm away from the second lens 22. The pupil surface of this embodiment is between the second lens 22 and the third lens 23, and spectral splitting can be achieved on this pupil surface.

[0058] In this embodiment, if there are two or more relay lens groups 2, different filters can be configured for the relay lens groups 2 so that the ultraviolet light source of this embodiment can produce light sources with different requirements and have multiple uses. At the same time, multiple independent pupil illumination modes can be realized.

[0059] In one embodiment, this embodiment can realize independent operation of different illumination schemes by configuring different pupil blocks (conventional illumination, annular illumination, quadrupole illumination) and bandpass filters, thereby realizing simultaneous and independent multi-illumination methods.

[0060] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A minimal coherence factor ultraviolet light source, characterized in that: include: An ultraviolet lamp, comprising light-emitting elements and connecting parts connected to each other; When the light-emitting element is irradiated, the end of the connecting member away from the light-emitting element forms a shadow portion; At least one relay mirror group, the entrance of which collects the uniform light of the light-emitting element, and the exit of which is the light outlet of the ultraviolet light source; Wherein: the uniform light does not include the shadow part.

2. The ultraviolet light source according to claim 1, characterized in that: The ultraviolet lamp is a mercury lamp, and the optical axis of the relay lens assembly is perpendicular to a cathode-anode connection line of the mercury lamp and passes through the center of the cathode-anode connection line.

3. The ultraviolet light source according to claim 2, characterized in that: The relay lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence from the object plane to the image plane; the optical path of the relay lens group is symmetrically arranged, and the optical axis passes through the light-emitting element; the radius of curvature of one side of the first lens is ≥300mm, which is used to fully couple and transmit large-angle light; the second lens and the third lens are both biconvex lenses, which are symmetrical about the relay center of the relay lens group; the fourth lens is a biconvex lens, which is used to converge the light of the third lens to the image plane.

4. The ultraviolet light source according to claim 3, characterized in that: The distance between the second lens and the third lens is ≥40 mm, and the incident angle of the third lens is ≤10°.

5. The ultraviolet light source according to claim 2, characterized in that: The ultraviolet light source also includes an adjusting reflector; the adjusting reflector is used to reflect the illumination light of the light emitting element at an end of the light emitting element away from the relay lens group, to compensate for the pupil of the relay lens group, and to make the pupil of the relay lens group symmetrical.

6. The ultraviolet light source according to claim 5, characterized in that: The adjustment reflector is a spherical reflector, the center of which is located at the light-emitting point of the light-emitting element, the diameter of the reflective surface is equal to the incident aperture of the relay lens group, and the line connecting the vertex and the center of the spherical reflector coincides with the optical axis of the relay lens group.

7. The ultraviolet light source according to claim 2, characterized in that: The relay mirror groups are two or more than two groups and are arranged on the periphery of the ultraviolet lamp.

8. The ultraviolet light source according to claim 7, characterized in that: The ultraviolet light source includes N groups of relay mirrors, which are symmetrical about the cathode-anode connection line of the light-emitting element and arranged annularly on the periphery of the ultraviolet lamp; a reflector is provided on the object surface; wherein: N=1, 2, 3...; the reflector is configured to semi-transmit and semi-reflect the light.

9. The ultraviolet light source according to claim 4, characterized in that: A pupil baffle is also arranged between the second lens and the third lens, and the pupil baffle is used to enable the exit port of the relay lens group to form traditional illumination, annular illumination or quadrupole illumination; the pupil baffle is 2-23 mm away from the second lens.

10. The ultraviolet light source according to claim 4, characterized in that: A filter is also arranged between the second lens and the third lens; the filter is 2-28 mm away from the second lens.

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