An extreme ultraviolet supercontinuum light source generating device and method of 10-20 nm waveband luminous efficiency

Abstract

The application belongs to the field of laser plasma, and discloses an extreme ultraviolet (EUV) supercontinuum light source generating device and method for a 10-20 nm wave band, which can be used for quantity detection in advanced semiconductor manufacturing. The device comprises a vacuum pump set, a vacuum chamber, a target material, an EUV spectrum measurement system, a laser, a half-wave plate and a polarizer combination, a focusing lens, and a beam expander. The vacuum chamber maintains a proper vacuum degree through air extraction by the vacuum pump, and the supercontinuum radiation of 10-20 nm is generated by irradiating the target material with a laser. After the spectrum radiation energy and the laser-EUV radiation conversion efficiency are quantified through the EUV spectrum measurement system and the radiation calibration and energy calculation method, the optimal focusing spot size under the best light-emitting efficiency of different laser wavelengths, laser pulse times and laser energies is obtained, and finally the maximum light-emitting efficiency of different laser parameters in the 10-20 nm wave band is realized.

Description

Technical Field

[0001] This invention belongs to the field of laser plasma and relates to an extreme ultraviolet (EUV) supercontinuum light source generating device and method with luminous efficiency in the 10-20nm wavelength band. Background Technology

[0002] In the semiconductor manufacturing field, extreme ultraviolet (EUV) lithography, based on laser-produced plasma (LPP) technology, has become a key technology for achieving mass production at 7nm and below process nodes. As the planar arraying of metal-oxide-semiconductor field-effect transistors (MOSFETs) on silicon wafers reaches its limit, technologies such as 3D NAND flash memory and gate-all-around (GAA) devices, with their scalability and high performance, are enabling the transformation of microchip manufacturing processes towards 3D geometries. However, this complex three-dimensional structure presents metrological challenges during manufacturing, requiring extremely high yields. Currently, the industry lacks a solution that meets both non-destructive requirements and is suitable for high-volume manufacturing (HVM).

[0003] The 10-20 nm wavelength range of EUV supercontinuum light sources has demonstrated unique advantages and potential in solving the aforementioned challenges in scattering measurement research. For example, its short wavelength resolution is higher than visible light; it can separate contour parameters from scattered signals within this wavelength range; and its broadband spectral characteristics allow it to carry a richer amount of information. Therefore, EUV supercontinuum light sources show great promise in key measurement and inspection stages of chip manufacturing, such as defect detection in EUV masks, EUV photoresist research, measurement of critical dimensions (CD) and overlay accuracy, and measurement of edge placement errors.

[0004] Therefore, to meet diverse detection needs, developing an extreme ultraviolet (EUV) supercontinuum (SUB) light source with high luminous efficiency in the 10-20 nm wavelength range is particularly important. Patent document CN105333953A discloses a tunable broadband laser-plasma EUV light source capable of generating EUV light with strong radiation in both the 13.X nm and 6.X nm wavelength bands. Furthermore, by controlling the laser power density acting on the target, the radiation intensity in both bands can be effectively controlled. However, the luminous efficiency of alloy targets in this band is significantly lower than that of pure tin targets. Moreover, the complexity of the laser-plasma radiation process means that relying solely on theoretical calculations to guide laser parameter adjustments, without the support of EUV spectral measurement and characterization techniques, makes it difficult to optimize luminous efficiency. Crucially, the focused spot size has a significant impact on the luminous efficiency of the EUV SUB, and the optimal focused spot size varies depending on the laser wavelength, laser pulse time, and laser energy. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides an extreme ultraviolet (EUV) supercontinuum light source generation device and method with luminous efficiency in the 10-20 nm band, which optimizes the radiation of LPP plasma in the 10-20 nm band to achieve high-efficiency extreme ultraviolet supercontinuum radiation.

[0006] The technical solution of this invention:

[0007] On one hand, the present invention provides an extreme ultraviolet supercontinuum light source generating device with luminous efficiency in the 10-20nm wavelength band, characterized in that it includes:

[0008] A vacuum chamber containing a target material is maintained at 10°C by a vacuum pump. -3 -10 -5 Pascal's vacuum;

[0009] A laser is used to emit a driving laser, which is focused by a focusing lens and then irradiates a target material to generate plasma and radiate an EUV supercontinuum light source. The wavelength range of the driving laser is 1 to 10 μm, and the output energy, pulse time, and laser focusing spot size of the laser are adjustable.

[0010] The EUV spectral measurement system is connected to the vacuum chamber via a flange and is used to measure the spectral distribution and radiant energy of the EUV supercontinuum light source.

[0011] A collecting mirror, located in or near the vacuum chamber, is used to collect EUV radiation generated by the plasma and guide it to the detection system.

[0012] A detection system is used to receive and analyze EUV radiation guided by a collecting mirror.

[0013] The target material is a tin target, which can be in liquid or solid form, and the emission peak of the indistinguishable transition peak (UTA) of the tin target material is around 13.5 nm. The computer measures, calibrates and calculates the energy of EUV radiation, which can quantify and characterize the radiation energy of 10-20 nm and the conversion efficiency of laser to 10-20 nm supercontinuum radiation.

[0014] Furthermore, it also includes:

[0015] A combination of a half-wave plate and a polarizer is disposed between the laser and the focusing lens to control the polarization state and intensity of the laser.

[0016] A beam expander is positioned between the focusing lens and the target material to increase the diameter of the laser beam so as to cover the surface of the target material.

[0017] The EUV spectral measurement system includes a first slit, a cylindrical mirror group, a plane mirror, a second slit, an EUV grating, and a detector arranged sequentially along the optical path, wherein the detector and the second slit are located at the front and rear focal lengths of the EUV grating, respectively.

[0018] Preferably, the vacuum pump assembly consists of a dry pump and a molecular pump to provide the required vacuum level.

[0019] Preferably, the target is placed on a movable or rotatable platform to facilitate adjustment of the target's position and angle.

[0020] Preferably, the surface of the collecting mirror is coated with Au or Ru to form a coating layer, thereby improving the reflection efficiency of 10-20nm supercontinuum radiation.

[0021] Preferably, using tin droplet targets allows for modulation of the target's morphology and density via a dual-pulse method. Solid tin, on the other hand, enables a simpler and more compact light source system.

[0022] Preferably, the laser type can be a solid-state laser, a gas laser, a fiber laser, etc., and the output energy, pulse time, and laser focusing spot size of the laser can be adjusted.

[0023] On the other hand, the present invention also provides a method for generating an extreme ultraviolet supercontinuum light source with a luminous efficiency of 10-20 nm using the above-mentioned device, characterized in that it includes the following steps:

[0024] S1. Set the wavelength, energy, pulse time, and focused spot size of the laser so that the laser shines on the target material through the focusing lens to generate plasma and emit 10-20nm EUV supercontinuum radiation.

[0025] S2. Collect and measure EUV supercontinuum radiation using an EUV spectral measurement system, and calculate the spectral distribution and radiant energy under the current parameters;

[0026] S3. The wavelength of the EUV spectral measurement system is calibrated using the absorption edges or characteristic spectral lines of ion emission from Si, Al, and Zr materials, and the efficiency of the EUV spectral measurement system is calibrated using a standard light source.

[0027] S4. With the laser wavelength, laser pulse time, and laser energy fixed, change the laser focused spot size and observe and record the EUV radiation energy;

[0028] S5. Based on the recorded EUV radiation energy, determine the focused spot size for optimal luminous efficiency under different laser wavelengths, laser pulse times, and laser energies.

[0029] Furthermore, it also includes the following steps:

[0030] S6. Apply the optimized parameters to actual production, and use the detection system to monitor and characterize the radiation energy and conversion efficiency of the EUV supercontinuum light source in real time.

[0031] Furthermore, step S3 also includes:

[0032] Based on wavelength calibration and efficiency calibration, S3.1 calculates the detector count and actual photon count response curves for different wavelengths in the EUV spectral measurement system.

[0033] S3.2 By using the response curve and detector counts, the total number of photons at different wavelengths of the EUV spectral system is calculated, and the radiation energy at different wavelengths is obtained.

[0034] S3.3 Based on the solid angle of EUV radiation received by the EUV spectral system, the radiation energy and conversion efficiency in the 10-20nm wavelength range under a 2π solid angle of the plasma are calculated.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention addresses the quantitative measurement needs in advanced semiconductor manufacturing by employing a laser-generated plasma-emitted EUV supercontinuum radiation mechanism, achieving in-depth quantification and precise characterization of EUV radiation energy and laser-EUV radiation conversion efficiency.

[0037] 1. By integrating EUV spectral measurement systems, radiation calibration techniques, and energy calculation methods, this invention precisely quantifies spectral radiation energy and laser-EUV radiation conversion efficiency, thereby determining the focused spot size that achieves optimal luminous efficiency under different laser parameters. Ultimately, it realizes the maximum luminous efficiency for different laser parameters.

[0038] 2. This invention successfully established a characterization model for laser-EUV radiation conversion efficiency. It not only revealed the influence of different laser parameters on EUV radiation efficiency but also provided a scientific basis for optimizing laser parameters. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the EUV supercontinuum light source generating device with high luminous efficiency in the 10-20 nanometer band according to Embodiment 1 of the present invention;

[0040] Figure 2 This is a schematic diagram of the optical path of the EUV spectral measurement system in this invention;

[0041] Figure 3 This is a schematic diagram of the 10-20nm supercontinuum radiation spectrum of the present invention;

[0042] In the diagram: 1. Vacuum pump assembly; 2. Vacuum chamber; 3. Target material; 4. EUV spectral measurement system; 41. First slit; 42. Cylindrical mirror assembly; 43. Plane mirror; 44. Second slit; 45. EUV grating; 46. Detector; 5. Laser; 6. Half-wave plate and polarizer assembly; 7. Focusing lens; 8. Collecting mirror; 9. Detection system; 10. Laser beam; 11. Extreme ultraviolet beam; 12. Beam expander; 13. Data transmission line; 14. Computer. Detailed Implementation

[0043] To make the technical solutions in the embodiments of the present invention clear and complete, the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] This embodiment provides a device and method for generating a high-efficiency EUV supercontinuum light source in the 10-20 nanometer wavelength range, aiming to meet the high-precision metrology and testing requirements in advanced semiconductor manufacturing. Please refer to... Figure 1 , Figure 1 This is a schematic diagram of the structure of the EUV supercontinuum light source generating device with high luminous efficiency in the 10-20 nanometer band according to an embodiment of the present invention. As shown in the figure, an EUV supercontinuum light source generating device with high luminous efficiency in the 10-20 nanometer band includes a vacuum chamber 2, a target material 3, an EUV spectral measurement system 4, a laser 5 and its supporting components, a collecting mirror 8, and a detection system 9.

[0045] Vacuum chamber 2: Maintained at 10 by vacuum pump assembly 1 -5 Pascal vacuum is used to ensure the effective transmission and measurement of EUV radiation.

[0046] The target 3, placed inside the vacuum chamber 3, uses tin as the target material, which can be in liquid or solid form. The main unresolved transition peak (UTA) emission peak of the tin target is located near 13.5 nm, making it suitable for generating EUV supercontinuum radiation in the 10-20 nm wavelength range. Liquid tin targets can have their morphology and density modulated using a dual-pulse method, while solid tin targets allow for a simpler and more compact light source system.

[0047] The EUV spectral measurement system 4, connected to the vacuum chamber 2 via a flange, is used to measure and characterize the spectral distribution and radiant energy of the EUV supercontinuum light source. For example... Figure 2 As shown, the optical path includes a first slit 41, a cylindrical mirror group 42, a plane mirror 43, a second slit 44, an EUV grating 45, and a detector 46 arranged sequentially along the optical path. The distance between the cylindrical mirror group and the grating and detector is related to the radius of curvature of the cylindrical mirror. The EUV grating, detector, and second slit should be placed at the front and rear focal lengths of the grating.

[0048] The first slit 41 is used to limit the range of light passing through, allowing only light of a specific direction or size to pass through. That is, the first slit ensures that the area of ​​light emitted by the light source illuminating the cylindrical group is smaller than the actual size of the cylindrical mirror group.

[0049] The cylindrical mirror group 42 focuses or diverges the light to adjust the focal length and spot size of the light, so that the spot size at the detector is smaller than the detector array.

[0050] Plane mirror 43 is used to reflect light to change the direction of light propagation and ensure that the light is parallel to the horizontal plane;

[0051] The second slit 44 is used to adjust the amount of light transmitted to the subsequent optical elements and the system's spectral resolution.

[0052] EUV grating 45 is used to diffract or disperse incident light so as to analyze the wavelength, intensity and other characteristics of light.

[0053] The detector 46 receives light from the EUV grating 45, converts it into an electrical signal, and transmits it to the computer 14 for data processing via the data transmission line 13.

[0054] Laser 5 and its supporting components: Laser 5 can be of various types, such as solid-state laser, gas laser, and fiber laser, and its output energy, pulse time, and laser focusing spot size can all be adjusted. The laser beam is controlled by a combination of a half-wave plate and a polarizer 6, and then focused onto the target material 3 by a focusing lens 7 and a beam expander to generate plasma and radiate EUV light.

[0055] Collection mirror 8: Used to collect the extreme ultraviolet beam generated by the plasma and transmit it to the detection system 9; it adopts a super toroidal mirror, KB elliptical cylindrical mirror group or other reflector or mirror group that can achieve focusing, and the surface coating layer is made of metals such as Au and Ru to improve the reflection efficiency of 10-20nm supercontinuum radiation.

[0056] Detection System 9: Used to analyze the extreme ultraviolet light beam generated by the plasma.

[0057] A method for generating an extreme ultraviolet (EUV) supercontinuum light source with luminous efficiency in the 10-20 nm wavelength band includes the following steps:

[0058] S1. Parameter Setting and Adjustment: Set the laser's wavelength, energy, pulse time, and focused spot size according to requirements. Perform preliminary measurements of EUV radiation using an EUV spectral measurement system to understand the spectral distribution and radiant energy under the current parameters.

[0059] S2. Spectral Measurement and Calibration: Wavelength and efficiency calibration of the EUV supercontinuum light source are performed using an EUV spectral measurement system. Wavelength calibration determines the system's spectral coverage, and efficiency calibration calculates the detector counts and the actual photon count response curves at different wavelengths. Wavelength calibration uses the absorption edges or ion emission characteristic spectral lines of materials such as Si, Al, and Zr to calibrate the wavelengths of the EUV spectral measurement system; efficiency calibration uses a standard light source to calibrate the overall efficiency of the EUV spectral measurement system. The total number of photons at different wavelengths of the EUV spectral system is obtained through the response curves and detector counts, and the radiation energy at different wavelengths is calculated. Based on the solid angle of the EUV spectral system receiving EUV radiation, the radiation energy and conversion efficiency in the 10-20 nm wavelength range at a plasma solid angle of 2π are calculated, allowing for the characterization and monitoring of the 10-20 nm wavelength radiation from the EUV supercontinuum light source.

[0060] S3. Focused Spot Size Optimization: With a fixed laser wavelength, energy, and pulse time, the change in EUV radiation energy is observed by varying the laser focused spot size. The radiation energy at different focused spot sizes is precisely measured using an EUV spectral measurement system, and the conversion efficiency is calculated. By comparing the conversion efficiencies at different focused spot sizes, the optimal focused spot size for luminous efficiency is determined.

[0061] S4. Parameter Adjustment and Iteration: Based on the optimal focused spot size, adjust and optimize the laser's wavelength, energy, and pulse time parameters. Repeat the steps of spectral measurement, calibration, and focused spot size optimization until the optimal combination of parameters that achieves maximum luminous efficiency under different laser configurations is found.

[0062] The optimized parameters were applied to actual production, and the radiant energy and conversion efficiency of the EUV supercontinuum light source were monitored and characterized in real time using a detection system. For example... Figure 3 As shown, the verification results demonstrate that the present invention can achieve the maximum luminous efficiency in the 10-20 nanometer wavelength band under different laser parameter configurations, providing strong technical support for high-precision measurement and testing in the semiconductor manufacturing field.

Claims

1. A device for generating an extreme ultraviolet supercontinuum light source with a luminous efficiency of 10-20 nm wavelength, characterized in that, include: A vacuum chamber containing a target material is maintained at 10°C by a vacuum pump assembly. -3 -10 -5 Pascal's vacuum; A laser is used to emit a driving laser, which is focused by a focusing lens and then irradiates a target material to generate plasma and radiate an EUV supercontinuum light source. The wavelength range of the driving laser is 1~10 μm, and the output energy, pulse time, and laser focusing spot size of the laser are adjustable. The EUV spectral measurement system, connected to the vacuum chamber, is used to measure the spectral distribution and radiant energy of the EUV supercontinuum light source and transmit the data to a computer. A collecting mirror, located in or near the vacuum chamber, is used to collect EUV radiation generated by the plasma and guide it to the detection system. A detection system for receiving and analyzing EUV radiation introduced by the collecting mirror; The target material is a tin target material, which is used in liquid or solid form, and the emission peak of the indistinguishable transition peak (UTA) of the tin target material is around 13.5 nm. The computer measures and calibrates the EUV radiation, and uses energy calculation methods to quantify and characterize the EUV radiation energy and the conversion efficiency between laser and EUV supercontinuum radiation, thereby determining the focused spot size that achieves the best luminous efficiency under different laser parameter configurations, and realizing the maximum luminous efficiency of different laser parameters.

2. The extreme ultraviolet supercontinuum light source generating device with luminous efficiency in the 10-20nm wavelength band according to claim 1, characterized in that, Also includes: A combination of a half-wave plate and a polarizer is disposed between the laser and the focusing lens to control the polarization state and intensity of the laser. A beam expander is positioned between the focusing lens and the target material to increase the diameter of the laser beam so as to cover the surface of the target material.

3. The extreme ultraviolet supercontinuum light source generating device with luminous efficiency in the 10-20nm wavelength band according to claim 1, characterized in that, The vacuum pump assembly consists of a dry pump and a molecular pump to provide the required vacuum level.

4. The extreme ultraviolet supercontinuum light source generating device with luminous efficiency in the 10-20nm wavelength band according to claim 1, characterized in that, The target is placed on a movable or rotatable platform to facilitate adjustment of the target's position and angle.

5. The extreme ultraviolet supercontinuum light source generating device with luminous efficiency in the 10-20nm wavelength band according to claim 1, characterized in that, The surface of the collecting mirror is coated with Au or Ru to form a coating layer, thereby improving the reflection efficiency of 10-20nm supercontinuum radiation.

6. The extreme ultraviolet supercontinuum light source generating device with luminous efficiency in the 10-20nm wavelength band according to any one of claims 1-5, characterized in that, The EUV spectral measurement system includes a first slit, a cylindrical mirror group, a plane mirror, a second slit, an EUV grating, and a detector arranged sequentially along the optical path, wherein the detector and the second slit are located at the front and rear focal lengths of the EUV grating, respectively.

7. A method for generating an extreme ultraviolet supercontinuum light source with a luminous efficiency of 10-20 nm using the apparatus according to any one of claims 1-6, characterized in that, The steps include the following: S1. Based on the quantity detection requirements in semiconductor manufacturing, set the wavelength, energy, pulse time and focused spot size of the laser so that the laser shines on the target material through the focusing lens to generate plasma and emit 10-20nm EUV supercontinuum radiation. S2. Use an EUV spectral measurement system to collect and measure EUV radiation to obtain the spectral distribution and radiant energy of the EUV supercontinuum under the current parameters; S3. Wavelength calibration of the EUV spectral measurement system is performed using the absorption edges or characteristic spectral lines of ion emission from Si, Al, and Zr materials, and efficiency calibration of the EUV spectral measurement system is performed using a standard light source. S4. With the laser wavelength, laser pulse time, and laser energy fixed, change the laser focused spot size and observe and record the EUV radiation energy. S5. Based on the recorded EUV radiation energy, determine the focused spot size for optimal luminous efficiency under different laser wavelengths, laser pulse times, and laser energies.

8. The method according to claim 7, characterized in that, It also includes the following steps: S6. Apply the optimized parameters to actual production, and use a detection system to monitor and characterize the radiation energy and conversion efficiency of the EUV supercontinuum light source in real time.

9. The method according to any one of claims 7 or 8, characterized in that, Step S3 further includes: Based on the wavelength calibration and efficiency calibration results, S3.1 calculates the detector count and the actual number of photons entering the EUV spectral measurement system response curves at different wavelengths; S3.2 By using the response curve and detector counts, the total number of photons at different wavelengths of the EUV spectral system is calculated, and the radiation energy at different wavelengths is obtained. S3.3 Based on the solid angle of EUV radiation received by the EUV spectral system, the radiation energy and conversion efficiency in the 10~20nm wavelength range under the 2π solid angle of the plasma are calculated.

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