A device and method for generating a Compton backscattering extreme ultraviolet light source

Abstract

This application discloses a device and method for generating a Compton backscattered extreme ultraviolet light source, relating to the field of extreme ultraviolet light source generation. The device comprises: a pulsed light wavefront tilting element for adjusting an incident laser pulse into a pulsed light with a tilted wavefront; an off-axis deformable parabolic mirror for focusing the tilted wavefront pulsed light to form a focal line or a focal string, and causing incident electron bunches to collide with the focal line or the focal string in sequence to form a Compton backscattered extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes multiple focal points formed in sequence; and the multiple focal points are located on the same straight line. This application forms a Compton backscattered extreme ultraviolet light source by cooperating with the pulsed light wavefront tilting element and the off-axis deformable parabolic mirror.

Description

Technical Field

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

[0002] Extreme ultraviolet (EUV) lithography technology enables the engraving of complex and tiny patterns on silicon wafers, enabling the construction of high-density, high-performance integrated circuits. As the chip industry produces increasingly smaller and more powerful chips, EUV lithography has become a key driver of the industry's progress. Currently, the light source used for EUV lithography is primarily a laser-produced plasma (LPP) light source. While LPP technology plays a central role in the production of sub-5nm process nodes, its further development is hampered by numerous factors, including its extremely low energy conversion efficiency and tin particle contamination. The former refers to the extremely low efficiency of converting laser energy into EUV radiation energy, typically below 1%. The latter refers to the fact that tin contamination in LPP technology requires frequent cleaning or replacement of optical components, resulting in significant costs. Summary of the Invention

[0003] The purpose of this 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 inverse scattering 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] An off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulsed light to form a focal line or a focal string, and to allow the incident electron bunch to collide with the focal line or the focal string in sequence to form a Compton inverse scattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes multiple focal points formed in sequence; and the multiple 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 tilted wavefront;

[0010] An off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulsed 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 inverse scattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes multiple focal points formed in sequence; and the multiple 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] This application provides a device and method for generating a Compton backscattered extreme ultraviolet light source. A pulsed light wavefront tilting element is used to adjust an incident laser pulse into a pulsed light with a tilted wavefront. An off-axis deformable parabolic mirror focuses the tilted wavefront pulsed light to form a focal line or focal string. Incident electron bunches are then sequentially collided with the focal line or focal string, forming a Compton backscattered extreme ultraviolet light source. This application utilizes the interaction of a pulsed light wavefront tilting element and an off-axis deformable parabolic mirror to form a Compton backscattered extreme ultraviolet light source. 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 following briefly introduces the drawings required for use in the embodiments. 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 creative work.

[0014] Figure 1 Schematic diagram of a device for generating a Compton backscattered extreme ultraviolet light source according to 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 backscattered 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 tilting element, 103-pulse light with tilted wavefront, 104-off-axis deformable parabolic mirror, 105-electron bunch, 106-focal line position or straight line where the focal string is located, 201-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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0020] In order to make the purpose, features and advantages of this application more obvious and easy to understand, this application is further described in detail below with reference to 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 includes:

[0022] Pulsed light wavefront tilting element 102 is used to adjust the incident laser pulse 101 into a pulsed light with a tilted wavefront 103. The pulsed light wavefront tilting element 102 is an optical dispersive element, including a grating or a prism. The incident laser pulse can be a plane wave laser pulse. The phase front of the tilted wavefront pulsed light 103 remains 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 inverse scattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes multiple focal points formed in sequence; the multiple focal points are located on the same straight line, such as Figure 1 The focal line position or the focal string position is shown as a straight line 106. 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, which includes steps 301 and 302.

[0025] In step 301 , the pulse light wavefront tilting element 102 is used to adjust the incident laser pulse 101 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 inverse scattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes multiple focal points formed in sequence; the multiple focal points are located on the same straight line.

[0027] In another exemplary embodiment of the present application, the method for generating a Compton inverse scattering 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 parameters of the wavefront tilted pulse light 103. The optical parameters are wave numbers.

[0030] Step 403 : 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 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 , an 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 tilt 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 generating curve 201 of the off-axis deformable parabolic mirror in the cylindrical coordinate system (r, θ, z) is:

[0034]

[0035] Wherein, 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 a 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. Due to 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 generating 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: Where f(z) is the function of the change 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 η of the off-axis deformable parabolic mirror is related to the moving speed of the focal line after the off-axis deformable parabolic mirror 104 is focused or the moving speed of the focal string v f The relationship is:

[0039]

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

[0041] Therefore, the expression for 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 adjusts the deformation of the off-axis deformable parabolic mirror 104 and the tilt angle between the pulse front and the phase front to equalize the velocity of the focal line or the focal string with the velocity of the incident electron bunch 105, thereby generating a highly coherently scattered Compton inversely scattered extreme ultraviolet light source. The velocity of the electron bunch 105 is βc, where β is the ratio of the electron velocity to the speed of light and is adjustable depending on the selected portion of the off-axis deformable parabolic mirror's 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 deformed parabolic mirror 104 so that the deformation of the off-axis deformed 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 this application, electrons and photons can be incident at any angle between 0 and 190 degrees. However, when electron bunch 105 is scattered at a 90-degree angle from laser pulse 101, the coherent radiation quality requirement for electron bunch 105 is minimal. This means that even at sizes larger than the photon wavelength, a certain degree of coherent scattering is achieved. This is because when the angle is near 90 degrees, only a small electron slice interacts with the photon. Within this slice, all electrons interact coherently. At other angles, the coherent scattering conditions are partially met, resulting in coherent enhancement.

[0048] In another exemplary embodiment of the present application, the method for generating a Compton inverse scattering 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 a Compton inverse scattered extreme ultraviolet light source further includes: determining the time difference when the wavefront tilted pulse light 103 reaches 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 when the wavefront tilted pulse light 103 reaches 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 Where Δt1 is the delay. Generally, when α→0, the delay 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 generating curve 201 of the modified off-axis deformable parabolic mirror is adjusted to The parameter η in , let 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 , which can achieve periodic changes in laser intensity within the focused linear region. Therefore, based on the Kapitza-Dirac effect, coherently enhanced output can be achieved.

[0063] This application uses an off-axis deformable parabolic mirror combined with wave-front tilted pulse laser technology to achieve a high-intensity, highly coherent Compton backscattered extreme ultraviolet light source. The important process is that after a laser pulse is incident on a wavefront tilting element (such as a grating or prism), 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 single focus after being converged by a traditional off-axis parabolic mirror. By adjusting the deformation of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front, the movement speed of the focus in the focusing straight line area can be matched with the movement speed of the incident electron pulse train, thereby obtaining a highly coherent Compton backscattered extreme ultraviolet light source.

[0064] The technical features of the above embodiments can 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 document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may 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 inverse scattering extreme ultraviolet light source, characterized in that: The device for generating the Compton inverse scattering 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; An off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulsed 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 inverse scattering 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; The wavefront-tilted pulsed light is focused 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, specifically comprising: determining the tilt angle between the pulse front and the phase front of the wavefront-tilted pulsed light; determining the deformation amount of the off-axis deformed parabolic mirror based on the optical parameters of the wavefront-tilted pulsed light; 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 deformed parabolic mirror and the tilt angle between the pulse front and the phase front; adjusting the deformation amount of the off-axis deformed parabolic mirror and the tilt angle between the pulse front and the phase front to make the moving speed of the focal line or the moving speed of the focal string equal to the movement speed of the incident electron bunch, so as to generate a Compton backscattering extreme ultraviolet light source with highly coherent scattering.

2. The device for generating a Compton inverse scattered 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 backscattered extreme ultraviolet light source, using the device for generating a Compton backscattered extreme ultraviolet light source according to claim 1 or 2, characterized in that: The method for generating the Compton inverse scattering extreme ultraviolet light source includes: A pulse light wavefront tilting element is used to adjust the incident laser pulse into a pulse light with tilted wavefront; An off-axis deformable parabolic mirror is used to focus the wavefront-tilted pulsed 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 inverse scattering extreme ultraviolet light source; the focal line is a straight line formed after focusing; the focal string includes multiple focal points formed in sequence; and the multiple focal points are located on the same straight line.

4. The method for generating a Compton inverse scattered extreme ultraviolet light source according to claim 3, wherein: The method for generating the Compton inverse scattering extreme ultraviolet light source further includes: determining a tilt angle between a pulse front and a phase front of the wavefront-tilted pulse light; determining a deformation amount of an off-axis deformable parabolic mirror based on optical parameters of the pulsed light with tilted wavefront; determining a moving speed of the focal line or a moving speed of the focal string based on a deformation amount of the off-axis deformable parabolic mirror and an inclination 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 inverse scattered extreme ultraviolet light source according to claim 4, wherein: The method for generating a Compton inverse scattered extreme ultraviolet light source further includes: adjusting the deformation of the off-axis deformable parabolic mirror so that the deformation of the off-axis deformable parabolic mirror is a spatial periodic function.

6. The method for generating a Compton inverse scattered extreme ultraviolet light source according to claim 4, wherein: The method for generating the Compton inverse scattering extreme ultraviolet light source further 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 inverse scattered extreme ultraviolet light source according to claim 4, wherein: 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: Determining an expression for an original generating 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; The moving speed of the focal line or the moving speed of the focal string is determined based on the expression of the original generating curve of the off-axis deformable parabolic mirror and the tilt angle between the pulse front and the phase front.

8. The method for generating a Compton inverse scattered extreme ultraviolet light source according to claim 7, wherein: The expression of the original generating curve of the off-axis deformable parabolic mirror is: Wherein, 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 a 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 inverse scattered extreme ultraviolet light source according to claim 7, wherein: 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 amount 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 inverse scattered extreme ultraviolet light source according to claim 3, wherein: The method for generating the Compton inverse scattering extreme ultraviolet light source further includes: determining an enhancement factor of the 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.

Images