Projection exposure photoetching light source system for semiconductor preparation

Abstract

The invention provides a projection exposure photoetching light source system for semiconductor preparation. The projection exposure photoetching light source system comprises a laser light source; the attenuation controller is used for actively controlling the output laser power; the light beam coupler is used for coupling the light beam to the homogenizing optical fiber; the homogenizing optical fiber is used for enabling the energy of the incident laser beam to be uniformly distributed on a horizontal plane; the collimation beam expander is used for expanding or reducing the diameter of an incident light beam to a certain multiple, and an input end divergence angle fine adjustment structure can be fixed after debugging and collimation, so that collimation and stability of an output light spot are ensured, and light is guided to the mask plate. The optical fiber is homogenized, a large number of reflectors and lenses, especially devices such as fly-eye lenses and slit diffractors, are omitted, the probability that light beams are affected by dust and device precision is greatly reduced, and the quality of the light beams is improved. Due to the fact that parts are greatly reduced, the production cost and the control difficulty of the whole photoetching system are greatly reduced, and stable and reliable laser for photoetching exposure can be provided.

Description

Technical Field

[0001] The invention relates to the field of lithography machine light sources, and in particular to a projection exposure lithography light source system for semiconductor preparation. Background Art

[0002] like Figure 5 As shown in , there are two key technical difficulties in the existing projection exposure technology: 1 is ultraviolet laser transmission; 2 is ultraviolet laser homogenization and shaping. Regarding laser transmission, the existing technology uses multiple reflectors to reflect and transmit the laser, in which each mirror has a fixed loss to the laser. After the superposition of the losses of multiple mirrors, the overall loss of the laser is large. In addition, the reflector surface has a certain roughness. Every time the laser passes through a mirror, the roughness and undulation of the mirror surface will affect the spatial transmission phase of the laser. The superposition of multiple reflectors and lenses will complicate the final laser output spatial energy distribution. Regarding ultraviolet laser homogenization and shaping, lens groups or diffraction elements are currently mainly used to homogenize the laser energy distribution, but adding lenses will increase laser loss, and its homogenization degree is low. As a laser transmission medium, homogenized optical fiber can achieve extremely low transmission loss and extremely high laser homogenization degree, and can achieve the replacement of the transmission optical path from the laser to the mask in lithography, simplifying the design difficulty of the lithography optical path. For example, a special optical fiber that realizes flat-top energy distribution and controls beam quality is recorded in CN114859459A. However, as materials have advanced, the corresponding exposure lithography system has not been optimized, and the existing system still has a lot of redundant equipment, which affects production efficiency, power consumption and equipment cost, such as the records in JPH0897125A and CN110431487A. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a projection exposure lithography light source system for semiconductor preparation, which greatly reduces the redundant equipment of the exposure lithography system, improves the laser utilization efficiency, and reduces the control difficulty, power consumption and manufacturing cost.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a projection exposure lithography light source system for semiconductor manufacturing, comprising: Laser light source; An attenuation controller for actively controlling the output laser power; A beam coupler, for coupling the beam to a homogenizing optical fiber; Homogenizing optical fiber, used to make the energy of the incident laser beam evenly distributed on the horizontal plane; The collimating beam expander is used to expand or reduce the diameter of the incident light beam to a certain multiple. The divergence angle fine-tuning structure at the input end can be fixed after debugging and collimation to ensure the collimation and stability of the output light spot and guide the light to the mask.

[0005] The preferred solution also includes: Mask plate, used for engraving and processing images; The projection objective is used to scale down the image beam on the mask and map it onto the silicon wafer.

[0006] In a preferred embodiment, the attenuation controller includes a mechanical aperture, a piezoelectric crystal aperture or a rotating wave plate attenuation controller.

[0007] In a preferred solution, the beam coupler is a focusing lens to reduce the light spot and transmit it into the homogenizing optical fiber; Alternatively, the beam coupler is a fusion structure, and when the laser light source is a laser fiber output, the laser fiber is fused with the homogenizing fiber.

[0008] In a preferred solution, a homogenizing fiber ring is provided on the homogenizing fiber, that is, the homogenizing fiber is coiled into a plurality of ring structures and fixed, so as to increase the homogenization degree of the laser.

[0009] In a preferred solution, a splitter coupler is further provided between the homogenizing optical fiber output port and the collimating beam expander input port, and the splitter coupler is used to split the incident light beam into multiple optical fiber beams, one of which is connected to the collimating beam expander input port, and the other is connected to the energy detector; The energy detector is used to detect laser energy fluctuations and provide feedback to adjust the laser output intensity of the laser light source.

[0010] In a preferred solution, the spot interface energy of the output light beam of the collimating beam expander is distributed in a flat-top manner.

[0011] In a preferred embodiment, the top surface of the flat top has a shape of square, rectangle, circle, ellipse, triangle or line.

[0012] In a preferred embodiment, the homogenized optical fiber is provided with a cladding and a core, and the cross-sectional shape of the core includes square, rectangular, circular, elliptical, triangular or linear.

[0013] In a preferred solution, the homogenization method of the homogenized optical fiber includes a gradient refractive index at the core, a deflection ring structure, or a spatial asymmetric structure with acute angles, square angles, and obtuse angles.

[0014] The invention provides a projection exposure lithography light source system for semiconductor preparation. By adopting a homogenizing optical fiber, a large number of reflectors and lenses, especially compound eye lenses, slit diffractors and other equipment are omitted, the probability of light beams being affected by dust and equipment precision is greatly reduced, and the quality of light beams is improved. Due to the large reduction of parts, the production cost and control difficulty of the entire lithography system are greatly reduced, and a stable and reliable laser for lithography exposure can be provided. The homogenizing optical fiber ring structure is set to further improve the laser homogenization effect. The coupling mode is adopted for light splitting, which has low loss, less interference and higher precision compared with the beam splitter in the prior art. The homogenizing optical fiber ring is set to achieve a balance between homogenization and energy attenuation, and can perform customized homogenization on the light source as needed. Compared with the prior art, the invention reduces the use of lenses and reduces the laser transmission loss; and the optical fiber is a closed waveguide transmission, which is not affected by dust in the environment. The conventional optical path lenses are greatly affected by dust, which opens up a new technical route for the development of lithography machines; and the optical path volume of the lithography machine in the prior art is large, and after being vibrated by the environment, relative displacement is easily generated between the lenses, and the light spot stability is reduced, while the homogenizing optical fiber of the invention is less affected by vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic diagram of the system structure of the present invention.

[0016] Figure 2 It is a schematic diagram of a preferred system structure of the present invention.

[0017] Figure 3 This is a diagram showing the Gaussian energy distribution effect of the homogenized optical fiber output laser of the present invention.

[0018] Figure 4 This is the energy distribution diagram of the output homogenized laser spot of the present invention.

[0019] Figure 5 A typical structural diagram of a photolithography machine in the prior art.

[0020] In the figure, there are laser light source 1, attenuation controller 2, beam coupler 3, homogenizing optical fiber 4, homogenizing optical fiber ring 41, splitter coupler 5, energy detector 6, beam position pointing detector 61, collimating beam expander 7, mask 8, projection objective 9, silicon wafer 10, translation stage 11, primary beam expander 12, secondary beam expander 121, beam stabilization system 13, first beam splitter 14, pupil converter 15, zoom light group 16, second beam splitter 17, conical mirror 18, fly-eye lens 19, pupil shape adjuster 20, condenser 21, uniformity adjuster 22, slit diffractor 23, coupling mirror group 24. DETAILED DESCRIPTION

[0021] Embodiment 1: like Figure 1 A projection exposure lithography light source system for semiconductor manufacturing, comprising: Laser light source 1; in this example, laser light source 1 includes ultraviolet (UV) light source, for example: g line: 436nm, i line: 365nm. Generated by a high-pressure mercury lamp, a specific emission line is selected by filtering. Deep ultraviolet DUV excimer laser light source, for example: KrF excimer laser: 248nm, ArF excimer laser: 193nm, F2 excimer laser: 157nm. Extreme ultraviolet (EUV) light source: The wavelength range is between 10nm and 15nm, and the commonly used EUV light source wavelength is 13.5nm. The EUV light source is obtained by bombarding tin droplets with high-energy lasers to generate plasma.

[0022] Attenuation controller 2, used for actively controlling the output laser power; A beam coupler 3, used to couple the beam to a homogenizing optical fiber 4; The homogenizing optical fiber 4 is used to make the energy of the incident laser beam evenly distributed on the horizontal plane; optionally, the homogenizing optical fiber 4 adopts the homogenizing optical fiber 4 described in CN117434733A of our company.

[0023] The collimator beam expander 7 is used to expand or reduce the incident light beam diameter to a certain multiple. The input end divergence angle fine-tuning structure can be fixed after debugging and collimation to ensure the collimation and stability of the output light spot and guide the light to the mask 8. The collimator beam expander 7 is a group of lenses, including at least one negative lens to diverge the incident light beam, and a positive lens to capture and refocus the light beam after the divergence of the negative lens, and finally form an enlarged and more parallel output light beam. The light source provided by the present invention is as follows Figure 3 as shown in .

[0024] The preferred solution is Figure 1 Also included: A mask plate 8, used for engraving and processing an image; A projection objective lens 9 is used to scale down the image beam on the mask and map it onto a silicon wafer 10; The silicon wafer 10 is mounted on a precision translation stage 11 .

[0025] In a preferred solution, the attenuation controller 2 includes a mechanical aperture, a piezoelectric crystal aperture or a rotating wave plate attenuation controller.

[0026] The rotating wave plate attenuation controller uses a half wave plate in conjunction with a polarization crystal. Rotating the half wave plate changes the polarization direction of the laser, causing the intensity of the light passing through the crystal to change.

[0027] In a preferred solution, the beam coupler 3 is a focusing lens to reduce the light spot and transmit it into the homogenizing optical fiber 4; Alternatively, the beam coupler 3 is a fusion structure, and when the laser light source 1 is a laser fiber output, the laser fiber is fused with the homogenizing fiber 4. In this example, an integrated optical waveguide coupler is preferred, that is, a multi-branch coupling structure is used to distribute multi-source beams to a single-core or multi-core homogenizing fiber 4.

[0028] Embodiment 2: Based on Example 1, the preferred solution is as follows Figure 2 In the embodiment, a homogenizing fiber ring 41 is provided on the homogenizing fiber 4, that is, the homogenizing fiber 4 is coiled into a plurality of ring structures and fixed to increase the homogenization degree of the laser. The homogenizing fiber ring 41 in this example can increase the homogenization degree of the laser by increasing the length. Due to the total reflection characteristics of the optical fiber, the attenuation of the laser power is small, and after a sufficient number of reflections, the homogenization degree of the laser is greatly improved. The present invention achieves the same or even better light source homogenization effect with a simpler structure than the prior art, and obtains a homogenized exposure light source suitable for a photolithography machine.

[0029] The homogenizing optical fiber ring 41 is obtained by winding the homogenizing optical fiber 4 described in CN117434733A of our company.

[0030] In the preferred solution, a splitter coupler 5 is further provided between the output port of the homogenizing optical fiber 4 and the input port of the collimating beam expander 7. The splitter coupler 5 is used to split the incident light beam into multiple optical fiber beams, one of which is connected to the input port of the collimating beam expander 7, and the other is connected to the energy detector 6. The energy detector 6 is used to detect laser energy fluctuations and feedback-adjust the laser output intensity of the laser light source 1 to improve the stability of the laser power. The laser energy detector in this example adopts, for example, the StarBright series of Coherent or the Vega series of Ophir Photonics.

[0031] In a preferred solution, the spot interface energy of the output light beam of the collimating beam expander 7 is distributed in a flat-top manner.

[0032] In a preferred embodiment, the top surface of the flat top has a shape of square, rectangle, circle, ellipse, triangle or line.

[0033] In a preferred solution, the homogenized optical fiber 4 is provided with a cladding and a core, and the cross-sectional shape of the core includes square, rectangular, circular, elliptical, triangular or linear.

[0034] In a preferred solution, the homogenization method of the homogenized optical fiber includes a gradient refractive index at the core, a deflection ring structure, or a spatial asymmetric structure with acute angles, square angles, and obtuse angles.

[0035] The deflected ring structure means that the core of the optical fiber is a uniform material distribution. By setting a different refractive index structure that deviates from the center of the circle in the core, such as a ring structure, the spatial symmetry of the overall structure is broken, so that the light beam is evenly distributed in the optical fiber transmission. The circle is an absolutely spatially symmetrical structure, which has countless symmetry axes passing through the circle; while structures such as acute angles, square angles and obtuse angles have only a few symmetry axes and are not absolutely spatially symmetrical structures. The transmission of laser light in an optical fiber is approximately the superposition of countless diffractions. Because of the absolute symmetry of the circle, the center of the diffraction intensity is distributed at the center of the circle; while asymmetric structures such as acute angles, square angles and obtuse angles avoid the center of the diffraction intensity being superimposed on the geometric center of the structure each time, and instead the intensity fills the entire asymmetric structure, thereby achieving homogenization of the laser spot. The homogenization effect of the present invention is as follows: Figure 3 , 4 as shown in .

[0036] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A projection exposure lithography light source system for semiconductor manufacturing, characterized in that Includes the following arranged in sequence: Laser light source (1); An attenuation controller (2) for actively controlling the output laser power; A beam coupler (3) for coupling the beam to a homogenizing optical fiber (4); A homogenizing optical fiber (4) for making the energy of the incident laser beam evenly distributed on a horizontal plane; The collimating beam expander (7) is used to expand or reduce the diameter of the incident light beam to a certain multiple. The divergence angle fine-tuning structure at the input end can be fixed after the collimation is debugged to ensure the collimation and stability of the output light spot and guide the light to the mask (8).

2. A projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that Also includes: A mask plate (8) for engraving an image; The projection objective lens (9) is used to scale down the image light beam on the mask plate and map it onto the silicon wafer (10).

3. The projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that: The attenuation controller (2) comprises a mechanical aperture, a piezoelectric crystal aperture or a rotating wave plate attenuation controller.

4. The projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that: The beam coupler (3) is a focusing lens for reducing the light spot and transmitting it into the homogenizing optical fiber (4); Alternatively, the beam coupler (3) is a fusion structure, and when the laser light source (1) is a laser optical fiber output, the laser optical fiber is fused with the homogenizing optical fiber (4).

5. The projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that: A homogenizing optical fiber ring (41) is provided on the homogenizing optical fiber (4), that is, the homogenizing optical fiber (4) is coiled into a plurality of ring structures and fixed, so as to increase the homogenization degree of the laser.

6. The projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that: A splitter coupler (5) is also provided between the output port of the homogenizing optical fiber (4) and the input port of the collimating beam expander (7), and the splitter coupler (5) is used to split the incident light beam into a plurality of optical fiber beams, one of which is connected to the input port of the collimating beam expander (7), and the other is connected to the energy detector (6); The energy detector (6) is used to detect laser energy fluctuations and to provide feedback to adjust the laser output intensity of the laser light source (1).

7. The projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that: The light spot interface energy of the output light beam of the collimating beam expander (7) is distributed in a flat top.

8. The projection exposure lithography light source system for semiconductor manufacturing according to claim 7, characterized in that: The top shapes of the flat roof include square, rectangle, circle, oval, triangle or line.

9. The projection exposure lithography light source system for semiconductor manufacturing according to claim 1, characterized in that: The homogenized optical fiber (4) is provided with a cladding and a fiber core, and the cross-sectional shape of the fiber core includes square, rectangular, circular, elliptical, triangular or linear.

10. A projection exposure lithography light source system for semiconductor manufacturing according to any one of claims 7 to 9, characterized in that: The homogenization methods of homogenizing optical fiber include gradient refractive index at the core, deflection ring structure, or spatial asymmetric structure with sharp angles, square angles and obtuse angles.

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