Compton inverse scattering extreme ultraviolet light source generation device and method

Abstract

The invention discloses a Compton inverse scattering extreme ultraviolet light source generation device and method, and relates to the field of extreme ultraviolet light source generation, and the device comprises a pulse light wave front inclination element which is used for adjusting an incident laser pulse into wave front inclined pulse light; the off-axis deformation parabolic mirror is used for focusing the wavefront inclined pulse light to form a focal line or a focal point string and enabling an incident electron beam group to sequentially collide with the focal line or the focal point string to form a Compton inverse scattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focus string comprises a plurality of focuses which are formed in sequence; and the plurality of focuses are positioned on the same straight line. According to the invention, through mutual cooperation of the pulse light wave front tilting element and the off-axis deformation parabolic mirror, a Compton inverse scattering extreme ultraviolet light source is formed.

Description

Technical Field

[0001] The present application relates to the field of generation of extreme ultraviolet light sources, and in particular to a device and method for generating a Compton backscattering extreme ultraviolet light source. Background Art

[0002] Extreme Ultra-Violet (EUV) lithography technology can carve complex and tiny patterns on silicon wafers to build high-density, high-performance integrated circuits. As the chip manufacturing industry produces smaller and smaller but more powerful chips, EUV lithography technology has become one of the key factors driving the industry forward. At present, the light source used for EUV lithography is mainly Laser-Produced Plasma (LPP) light source. Although LPP technology plays a core role in the production of process nodes below 5 nanometers, its further development is restricted by many factors. These include the extremely low energy conversion efficiency of the technology and the problem of tin particle contamination. The former refers to the very low efficiency of converting laser energy into EUV radiation energy, which is usually less than 1%. The latter refers to the fact that in LPP technology, the problem of tin contamination will cause frequent cleaning or replacement of optical components, which brings a huge cost burden. Summary of the invention

[0003] The purpose of the present application is to provide a device and method for generating a Compton backscattered extreme ultraviolet light source, which can form a Compton backscattered extreme ultraviolet light source by cooperating with a pulse light wavefront tilt element and an off-axis deformable parabolic mirror.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a device for generating a Compton backscattering extreme ultraviolet light source, comprising:

[0006] A pulse light wavefront tilting element, used for adjusting an incident laser pulse into a pulse light with a tilted wavefront;

[0007] The off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulse light to form a focal line or a focal string, and to make the incident electron bunch collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes a plurality of focal points formed in sequence; and the plurality of focal points are located on the same straight line.

[0008] In a second aspect, the present application provides a method for generating a Compton inverse scattering extreme ultraviolet light source, comprising:

[0009] A pulse light wavefront tilting element is used to adjust the incident laser pulse into a pulse light with a tilted wavefront;

[0010] An off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulse light to form a focal line or a focal string, and the incident electron bunch is made to collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes a plurality of focal points formed in sequence; and the plurality of focal points are located on the same straight line.

[0011] According to the specific embodiments provided in this application, this application has the following technical effects:

[0012] The present application provides a device and method for generating a Compton backscattering extreme ultraviolet light source, wherein an incident laser pulse is adjusted to a pulse light with a tilted wavefront through a pulse light wavefront tilting element; the pulse light with a tilted wavefront is focused through an off-axis deformable parabolic mirror to form a focal line or a focal string, so that the incident electron bunches collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source. The present application forms a Compton backscattering extreme ultraviolet light source by cooperating with a pulse light wavefront tilting element and an off-axis deformable parabolic mirror. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is a schematic diagram of a device for generating a Compton backscattering extreme ultraviolet light source in one embodiment of the present application;

[0015] Figure 2 A schematic diagram of the structure of an off-axis deformable parabolic mirror in a device for generating a Compton backscattering extreme ultraviolet light source provided in one embodiment of the present application;

[0016] Figure 3 A schematic flow chart of a method for generating a Compton backscattering extreme ultraviolet light source provided in another embodiment of the present application.

[0017] Reference numerals:

[0018] 101-laser pulse, 102-pulse light wavefront tilt element, 103-pulse light with tilted wavefront, 104-off-axis deformable parabolic mirror, 105-electron bunch, 106-the position of the focal line or the straight line where the focus string is located, 201-the original mother curve of the off-axis deformable parabolic mirror. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] In an exemplary embodiment, Figure 1 As shown, a device for generating a Compton backscattering extreme ultraviolet light source is provided, and the device for generating a Compton backscattering extreme ultraviolet light source comprises:

[0022] The pulse light wavefront tilting element 102 is used to adjust the incident laser pulse 101 into a wavefront tilted pulse light 103. The pulse light wavefront tilting element 102 is an optical dispersion element, including a grating or a prism. The incident laser pulse can be a plane wave laser pulse. The phase front of the wavefront tilted pulse light 103 is still perpendicular to the propagation direction.

[0023] The off-axis deformable parabolic mirror 104 is used to focus the wavefront tilted pulse light 103 to form a focal line or a focal string, and to make the incident electron bunch 105 collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes a plurality of focal points formed in sequence; the plurality of focal points are located on the same straight line, such as Figure 1 The focal line position or the focal string straight line 106 is shown. The extreme ultraviolet light source is an electromagnetic wave with a wavelength less than 100 nm.

[0024] Based on the same inventive concept, an embodiment of the present application further provides a method for generating a Compton backscattering extreme ultraviolet light source, and the method for generating a Compton backscattering extreme ultraviolet light source includes steps 301 to 302.

[0025] Step 301 : Using the pulse light wavefront tilting element 102 , the incident laser pulse 101 is adjusted into a pulse light 103 with a tilted wavefront.

[0026] Step 302, using an off-axis deformable parabolic mirror 104 to focus the wavefront tilted pulse light 103 to form a focal line or a focal string, and allowing the incident electron bunch 105 to collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes a plurality of focal points formed in sequence; the plurality of focal points are located on the same straight line.

[0027] In another exemplary embodiment of the present application, the method for generating a Compton backscattering extreme ultraviolet light source further includes steps 401 to 404.

[0028] Step 401 , determining the tilt angle between the pulse front and the phase front of the wavefront tilted pulse light 103 .

[0029] Step 402: Determine the deformation amount of the off-axis deformable parabolic mirror 104 based on the optical parameter of the wavefront tilted pulse light 103. The optical parameter is the wave number.

[0030] Step 403: Determine the moving speed of the focal line or the moving speed of the focal string based on the deformation amount of the off-axis deformable parabolic mirror 104 and the tilt angle between the pulse front and the phase front.

[0031] In a specific application example, step 403 specifically includes:

[0032] Based on the deformation amount of the off-axis deformable parabolic mirror 104 and the main focal length of the off-axis deformable parabolic mirror 104, the expression of the original generating curve 201 of the off-axis deformable parabolic mirror is determined.

[0033] Based on the expression of the original generatrix 201 of the off-axis deformable parabolic mirror and the inclination angle between the pulse front and the phase front, the moving speed of the focal line or the moving speed of the focal string is determined. Figure 2 As shown, the expression of the original mother curve 201 of the off-axis deformable parabolic mirror in the cylindrical coordinate system (r, θ, z) is:

[0034]

[0035] Among them, f0 is the main focal length of the off-axis deformable parabolic mirror 104, η is the deformation of the off-axis deformable parabolic mirror 104, z is the distance from the point on the off-axis deformable parabolic mirror 104 to the optical axis, and r is the radius of the off-axis deformable parabolic mirror 104. If η=0, it is a conventional off-axis parabolic mirror; if η<0, the off-axis parabolic mirror is compressed; if η>0, the off-axis parabolic mirror is stretched. Therefore, it is called an off-axis deformable parabolic mirror 104. In this application, it is assumed that θ=0 in the cylindrical coordinate system (r, θ, z), and the two-dimensional case (r, z) is focused. Because of the rotational symmetry of the off-axis compression-stretching parabolic mirror, it can be directly extended to θ≠0.

[0036] In general, if |η|<<1 is maintained, the expression of the original mother curve 201 of the off-axis deformable parabolic mirror can be transformed into:

[0037] The functional relationship between the focus f of the off-axis parabola and the change of z is: Wherein, f(z) is the variation function of the focus of the off-axis parabola.

[0038] It can be seen that when η→0, f=f0, that is, the off-axis deformable parabolic mirror 104 degenerates into a traditional off-axis parabolic mirror, and the focus is a fixed value f0. The deformation amount η of the off-axis deformable parabolic mirror is related to the moving speed of the focal line of the off-axis deformable parabolic mirror 104 after focusing or the moving speed v of the focal string f The relationship is:

[0039]

[0040] Wherein, ΔL is the optical path difference, and Δf is the difference in the focusing position of light with different optical path differences.

[0041] Therefore, the expression of the moving speed of the focal line or the moving speed of the focal string is:

[0042]

[0043] Among them, v f is the moving speed of the focal line or the moving speed of the focal string, f0 is the main focal length of the off-axis deformable parabolic mirror 104, η is the deformation amount of the off-axis deformable parabolic mirror 104, c is the speed of light, α is the inclination angle between the pulse front and the phase front, z is the distance from the point on the off-axis deformable parabolic mirror 104 to the optical axis, and r is the radius of the off-axis deformable parabolic mirror 104.

[0044] Step 404, adjusting the deformation of the off-axis deformable parabolic mirror 104 and the tilt angle between the pulse front and the phase front, so that the moving speed of the focal line or the moving speed of the focus string is equal to the moving speed of the incident electron bunch 105, so as to generate a highly coherently scattered Compton backscattering extreme ultraviolet light source. The moving speed of the electron bunch 105 is βc, where β is the ratio of the electron speed to the speed of light, and is adjustable according to the different parts of the selected off-axis deformable parabolic mirror parent surface.

[0045] In another exemplary embodiment of the present application, the method for generating the Compton backscattered extreme ultraviolet light source also includes: adjusting the deformation of the off-axis deformable parabolic mirror 104 so that the deformation of the off-axis deformable parabolic mirror 104 is a spatial periodic function, which can form a periodic focus string in the focusing area, further enhancing the coherent scattering of the Compton backscattered extreme ultraviolet light source.

[0046] To maintain coherent scattering, the length of the electron bunch 105 must be smaller than the wavelength of the incident radiation to ensure that all electrons radiate with the same phase.

[0047] In the present application, electrons and photons can be incident at any angle from 0 to 190 degrees, but when the electron bunch 105 and the laser pulse 101 are scattered at an angle of 90 degrees, the coherent radiation has the lowest quality requirement for the electron bunch 105, that is, a certain coherent scattering can be achieved at a size larger than the wavelength of the photon. This is because when the angle between the two is near 90 degrees, only a small electron slice interacts with the photon. In this slice, all electrons interact with each other in a coherent manner. The coherent scattering conditions at other angles will be partially met, and there will also be coherent enhancement.

[0048] In another exemplary embodiment of the present application, the method for generating the Compton backscattering extreme ultraviolet light source further includes:

[0049] The enhancement factor of the Compton backscattering extreme ultraviolet light source is determined according to the scattering angle of the focused pulse light 103 with tilted wavefront and the scattering angle of the electron bunch 105 .

[0050] The light field intensity of the Compton backscattered extreme ultraviolet light source is determined based on the enhancement factor.

[0051] In this application, under the most ideal scattering angle of 90 degrees, the enhancement factor is:

[0052]

[0053] Among them, N e is the number of electrons, N l is the number of photons in the laser pulse 101, λ s is the wavelength of the scattered photon, γ is the relativistic factor of the electron, σ z,L is the pulse width of the wavefront tilted pulse light 103 along the propagation direction after focusing, is a geometric factor, θ L is the scattering angle.

[0054] It can be seen that due to the coherence effect, the enhancement factor is proportional to N e N l , therefore, a high-intensity and highly coherent Compton backscattered extreme ultraviolet light source can be obtained.

[0055] In another exemplary embodiment of the present application, the method for generating the Compton backscattered extreme ultraviolet light source further includes: determining the time difference for the wavefront tilted pulse light 103 to reach the off-axis deformable parabolic mirror 104 based on the tilt angle between the pulse front and the phase front and the radius of the off-axis deformable parabolic mirror 104. The time for the wavefront tilted pulse light 103 to reach the off-axis deformable parabolic mirror 104 is delayed in proportion to the radius of the off-axis deformable parabolic mirror 104, and the specific delay amount is Among them, Δt1 is the delay amount. Generally, when α→0, the delay amount can be approximated as

[0056] In another exemplary embodiment of the present application, a coherent Compton inverse scattering extreme ultraviolet light source with a scattering angle of 90 degrees is calculated based on an off-axis deformable parabolic mirror, as shown in Table 1. Table 1 gives the input parameters of an application example and the numerical estimation results of its light output. Under the laser parameter indicators, 10 16 photons / s Coherent photon flux.

[0057] Table 1

[0058]

[0059]

[0060] In another exemplary embodiment of the present application, the expression of the original generatrix 201 of the modified off-axis deformable parabolic mirror is adjusted as follows: The parameter η in is set as η = η0sink w z.

[0061] Among them, η0 and k w is a constant. According to the functional relationship between the focus f of the off-axis parabola and the change of z, It can be obtained that the focused linear region is,

[0062] By adjusting the wave number k w , the periodic variation of laser intensity can be achieved in the focused linear region. Therefore, based on the Kapitza-Dirac effect, coherent enhanced output can be achieved.

[0063] This application realizes a high-intensity, high-coherence Compton backscattering extreme ultraviolet light source by combining an off-axis deformable parabolic mirror with a wavefront tilted pulse laser technology. Among them, the important process is that after a laser pulse is incident on a wavefront tilting element (such as a grating or a prism, etc.), its wavefront changes to form a wavefront tilted pulse light; after this wavefront tilted pulse light is emitted to the off-axis deformable parabolic mirror, it converges in a straight line area, rather than a focus after the traditional off-axis parabolic mirror converges; by adjusting the deformation amount of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front, the moving speed of the focus in the focusing straight line area can be matched with the moving speed of the incident electron pulse train, thereby obtaining a highly coherent Compton backscattering extreme ultraviolet light source.

[0064] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A device for generating a Compton backscattering extreme ultraviolet light source, characterized in that: The device for generating the Compton backscattering extreme ultraviolet light source comprises: A pulse light wavefront tilting element, used for adjusting an incident laser pulse into a pulse light with a tilted wavefront; The off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulse light to form a focal line or a focal string, and to make the incident electron bunch collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes a plurality of focal points formed in sequence; and the plurality of focal points are located on the same straight line.

2. The device for generating a Compton backscattering extreme ultraviolet light source according to claim 1, characterized in that: The pulse light wavefront tilting element includes a grating or a prism.

3. A method for generating a Compton backscattering extreme ultraviolet light source, using the device for generating a Compton backscattering extreme ultraviolet light source according to claim 1 or 2, characterized in that: The method for generating the Compton backscattering extreme ultraviolet light source comprises: A pulse light wavefront tilting element is used to adjust the incident laser pulse into a pulse light with a tilted wavefront; An off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulse light to form a focal line or a focal string, and the incident electron bunch is made to collide with the focal line or the focal string in sequence to form a Compton backscattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes a plurality of focal points formed in sequence; and the plurality of focal points are located on the same straight line.

4. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 3, characterized in that: The method for generating the Compton backscattering extreme ultraviolet light source also includes: Determining the tilt angle between the pulse front and the phase front of the wavefront tilted pulse light; Determining the deformation amount of the off-axis deformable parabolic mirror based on the optical parameters of the pulsed light with tilted wavefront; Determining the moving speed of the focal line or the moving speed of the focal string based on the deformation amount of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front; The deformation amount of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front are adjusted so that the moving speed of the focal line or the moving speed of the focus string is equal to the moving speed of the incident electron bunch.

5. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 4, characterized in that: The method for generating a Compton inverse scattered extreme ultraviolet light source further includes: adjusting the deformation amount of the off-axis deformable parabolic mirror so that the deformation amount of the off-axis deformable parabolic mirror is a spatial periodic function.

6. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 4, characterized in that: The method for generating the Compton backscattering extreme ultraviolet light source also includes: The time when the pulse light with tilted wavefront reaches the off-axis deformable parabolic mirror is determined based on the tilt angle between the pulse front and the phase front and the radius of the off-axis deformable parabolic mirror.

7. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 4, characterized in that: Determining the moving speed of the focal line or the moving speed of the focal string based on the deformation amount of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front specifically includes: Determine an expression of an original generative curve of the off-axis deformable parabolic mirror based on the deformation amount of the off-axis deformable parabolic mirror and the main focal length of the off-axis deformable parabolic mirror; Based on the expression of the original mother curve of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front, the moving speed of the focal line or the moving speed of the focus string is determined.

8. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 7, characterized in that: The expression of the original generative curve of the off-axis deformable parabolic mirror is: Among them, f0 is the main focal length of the off-axis deformable parabolic mirror, η is the deformation of the off-axis deformable parabolic mirror, z is the distance from the point on the off-axis deformable parabolic mirror to the optical axis, and r is the radius of the off-axis deformable parabolic mirror.

9. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 7, characterized in that: The expression of the moving speed of the focal line or the moving speed of the focal string is: Among them, v f is the moving speed of the focal line or the moving speed of the focal string, f0 is the main focal length of the off-axis deformable parabolic mirror, η is the deformation of the off-axis deformable parabolic mirror, c is the speed of light, α is the inclination angle between the pulse front and the phase front, z is the distance from the point on the off-axis deformable parabolic mirror to the optical axis, and r is the radius of the off-axis deformable parabolic mirror.

10. The method for generating a Compton backscattering extreme ultraviolet light source according to claim 3, characterized in that: The method for generating the Compton backscattering extreme ultraviolet light source also includes: Determining an enhancement factor of a Compton backscattering extreme ultraviolet light source according to a scattering angle of the focused pulse light with tilted wavefront and a scattering angle of the electron bunch; The light field intensity of the Compton backscattered extreme ultraviolet light source is determined based on the enhancement factor.

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