阅读说明：本技术 一种照明光路系统及曝光光学系统 (Illumination light path system and exposure optical system ) 是由 李金� 胥涛棚 张雷 于 2021-08-06 设计创作，主要内容包括：本发明提出三段式照明光路系统,包括：前段子系统,用于收集照明光路前端的匀光部件出射的光束,中段子系统,用于对前段子系统输出的光束进一步汇聚,后段子系统,用于将中段子系统汇聚后的光束投射至数字微镜器件上,通过调整中段子系统的焦距改变照明光路系统的放大倍率,从而可以选择较大的放大倍率来降低对匀光部件的加工要求。(The invention provides a three-section type illumination light path system, which comprises: the front section subsystem is used for collecting light beams emitted by the dodging component at the front end of the illumination light path, the middle section subsystem is used for further converging the light beams output by the front section subsystem, the rear section subsystem is used for projecting the light beams converged by the middle section subsystem onto the digital micromirror device, and the magnification of the illumination light path system is changed by adjusting the focal length of the middle section subsystem, so that the processing requirement on the dodging component can be reduced by selecting larger magnification.)

1. An illumination optical path system, the illumination optical path system being a telecentric optical system, the illumination optical path system comprising:

the front-section subsystem is used for collecting light beams emitted by the light homogenizing component at the front end of the illumination light path;

the middle section subsystem is used for further converging the light beams output by the front section subsystem;

the rear section subsystem is used for projecting the light beams converged by the middle section subsystem onto the digital micromirror device;

the illumination optical path system changes the magnification of the illumination optical path system by adjusting the focal length of the middle section subsystem.

2. The illumination optical path system according to claim 1, wherein the lens used in any subsystem is a spherical lens.

3. The illumination optical path system of claim 1, wherein the front stage subsystem includes a meniscus lens, and the front surface has a radius of curvature greater than the radius of curvature of the back surface.

4. The illumination optical path system according to claim 3, wherein the front surface and the rear surface of the meniscus lens are non-concentrically arranged, and a distance between spherical centers of the front surface and the rear surface is greater than 10 mm.

5. The illumination optical path system of claim 1, wherein the mid-section subsystem comprises a first biconcave lens and a first biconvex lens, the first biconcave lens being forward and the first biconcave lens being rearward in a propagation path of the light beam.

6. The illumination light path system of claim 5, wherein the mid-section subsystem further comprises a convex planar lens located between the first bi-convex lens and the first bi-concave lens.

7. The illumination optical path system of claim 1, wherein the back stage subsystem comprises a second biconvex lens and a deflection assembly.

8. The illumination optical path system of claim 7, wherein the deflection assembly comprises a mirror positioned between the midsection subsystem and the second biconvex lens and a TIR prism positioned between the second biconvex lens and the dmd.

9. The illumination optical path system of claim 1, wherein the product of the focal length of the mid-section subsystem and the magnification of the illumination optical path system is in the range of 150mm-170 mm.

10. The illumination optical path system of claim 1, wherein a first distance D1 between the front stage subsystem and the middle stage subsystem is in a range of 15mm ≦ D1 ≦ 50mm, a second distance D2 between the middle stage subsystem and the back stage subsystem is in a range of 50mm ≦ D2 ≦ 200mm, and a third distance D3 between the back stage subsystem and the digital micromirror device is in a range of 50mm ≦ D3 ≦ 300 mm.

11. The illumination optical path system according to claim 1, wherein the dot diagram rms of the illumination optical path system is between 0.05 and 0.15, and the 100% dot diagram is between 0.2 and 0.4.

12. An exposure optical system characterized by comprising: a light source, a light unifying unit, an illumination optical path system according to any one of claims 1 to 11, a spatial light modulator, and a projection optical system.

Technical Field

The invention belongs to the technical field of laser projection, and particularly relates to an illumination light path system.

Background

DLP (Digital Light Processing) technology is a development technology that uses a DMD (Digital Micromirror Device) as a key Processing element to realize a Digital optical Processing process, and is widely used in the fields of projection display, special illumination, photolithography Processing, and the like. DLP systems typically include a light source, a light homogenizing element (often a light homogenizing rod), an illumination light path system, a digital micromirror device, and a projection optics system. In the optical system of the direct write lithography machine shown in fig. 1, a light beam generated by a light source 1 enters a light homogenizing part 2 after being collimated, and enters an illumination optical path system 3 after being homogenized, the illumination optical path system 3 projects (images) object surface light at the light emitting position of the light homogenizing part 2 onto a micromirror array of a DMD 4, and the DMD is used as a light modulation part to project the modulated light beam to a projection optical system 5 for imaging.

In the whole DLP system, the processing effect of the illumination light path system on the light beam directly determines the final projection effect of the projection lens. Key indicators of the illumination system include telecentricity, magnification, rear intercept, utilization, and the like. The DMD is used as a core component, and the design of the illumination optical path system also needs to be determined according to the requirements of the DMD. The size of the light spot projected by the illumination optical path system onto the micromirror array of the DMD needs to be equal to or slightly larger than the whole size of the micromirror array, which depends on the multiplying power of the illumination optical path system. In the prior art, although the illumination optical system shown in patent CN205388665U is compatible with DMDs of multiple specifications, the light exit surface area of the light uniformizing element is required to be large due to the small magnification, the length of the light uniformizing element must be long enough under the condition of ensuring the light uniformizing effect, and the large-size light uniformizing element has high processing difficulty and high cost. In addition, the system adopts an aspheric lens, and the complex processing technology of the aspheric lens also causes the cost to be too high.

Disclosure of Invention

The invention aims to provide an illumination light path system to solve the problem that the front end of the existing illumination system needs a large-size light-homogenizing component, so that the processing is difficult and the cost is high. Therefore, the invention adopts the following technical scheme:

an illumination optical path system, the illumination optical path system being a telecentric optical system, the illumination optical path system comprising: the front-section subsystem is used for collecting light beams emitted by the light homogenizing component at the front end of the illumination light path; the middle section subsystem is used for further converging the light beams output by the front section subsystem; the rear section subsystem is used for projecting the light beams converged by the middle section subsystem onto the digital micromirror device; the illumination optical path system changes the magnification of the illumination optical path system by adjusting the focal length of the middle section subsystem.

Preferably, the lens adopted by any subsystem is a spherical lens.

Preferably, the anterior segment subsystem includes a meniscus lens, the anterior surface having a radius of curvature greater than the posterior surface.

Preferably, the front surface and the rear surface of the meniscus lens are arranged non-concentrically, and the distance between the spherical centers of the front surface and the rear surface is greater than 10 mm.

Preferably, the mid-section subsystem comprises a first biconcave lens and a first biconvex lens, the first biconcave lens being in front and the first biconcave lens being in back in the propagation path of the light beam.

Preferably, the middle-stage subsystem further includes a convex flat lens located between the first biconvex lens and the first biconcave lens, and a light-emitting surface of the convex flat lens is an approximate plane.

Preferably, the posterior segment subsystem includes a second biconvex lens and a deflection assembly.

Preferably, the deflection assembly includes a mirror between the midsection subsystem and the second biconvex lens and a TIR prism between the second biconvex lens and the dmd.

Preferably, the product of the focal length of the middle section subsystem and the magnification of the illumination optical path system is in the range of 150mm-170 mm.

Preferably, the first distance D1 between the front-stage subsystem and the middle-stage subsystem is 15mm ≤ D1 ≤ 50mm, the second distance D2 between the middle-stage subsystem and the back-stage subsystem is 50mm ≤ D2 ≤ 200mm, and the third distance D3 between the back-stage subsystem and the digital micromirror device is 50mm ≤ D3 ≤ 300 mm.

Preferably, the dot sequence rms of the illumination light path system is between 0.05 and 0.15, and the 100% dot sequence is between 0.2 and 0.4.

Compared with the prior art, the three-section type illumination light path system has the advantages that through the structural design of the three-section type system, the mutual influence among the front-section subsystem, the middle-section subsystem and the rear-section subsystem is small, so that the internal structures of the front-section subsystem, the middle-section subsystem and the rear-section subsystem can be respectively designed according to the requirements of the front-section, the middle-section and the rear-section subsystems, and the tolerance of the illumination light path system is improved. The magnification of the illumination optical path system is changed by the focal length design of the middle-section subsystem, so that the system can obtain the required proper magnification, and the processing difficulty of the front end dodging component is reduced. The larger distance between the rear-section subsystem and the digital micromirror device ensures that the rear intercept of the system is sufficient, which is beneficial to enriching the turning design of the light path.

Drawings

FIG. 1 is an optical system of an exemplary direct write lithography machine of the present invention.

Fig. 2 is an exemplary illumination light path system of the present invention.

FIG. 3 shows a first deflection mode of the illumination optical path system of the present invention.

FIG. 4 shows a second deflection mode of the illumination optical path system of the present invention.

FIG. 5 shows a third deflection type of the illumination optical path system of the present invention.

Fig. 6 is a corresponding example of the focal length of the middle subsystem and the magnification of the illumination optical path system.

Fig. 7 is a dot diagram of an exemplary illumination optical path system.

Detailed Description

In order to make the technical solution of the present invention more clear, embodiments of the present invention will be described below with reference to the accompanying drawings.

The illumination optical path system of the present invention is a telecentric optical system, and adopts a critical illumination mode, as shown in fig. 2. The object image space telecentricity of the system is less than 10mrad, and the influence of the telecentricity error of an illumination light path system on a subsequent projection system is reduced as much as possible. Specifically, the illumination optical path system includes a front-stage subsystem 10, a middle-stage subsystem 20, and a rear-stage subsystem 30, which are sequentially arranged. The front-end subsystem 10 is configured to collect light beams emitted from the light uniformizing component at the front end of the illumination light path into the middle-end subsystem 20, the middle-end subsystem 20 is configured to further converge the light beams output by the front-end subsystem 10, and the rear-end subsystem 30 is configured to project the light beams converged by the middle-end subsystem 20 onto the digital micromirror device. The illumination light path system adopts a three-section system architecture, and the front section subsystem, the middle section subsystem and the rear section subsystem have small mutual influence, so that the internal structures of the front section subsystem, the middle section subsystem and the rear section subsystem can be respectively designed according to the requirements of the front section subsystem, the middle section subsystem and the rear section subsystem, thereby improving the tolerance of the illumination light path system and increasing the expansion space.

The following describes the configuration of each subsystem in the illumination optical path system in detail.

The front-end subsystem 10 is designed to include only the meniscus lens 11, and the meniscus lens 11 is a spherical lens whose front surface and rear surface are non-concentrically arranged, the front surface refers to an incident surface of the light beam emitted from the dodging component entering the meniscus lens 11, and the rear surface refers to an exit surface of the light beam. Preferably, the radius of curvature of the anterior surface is slightly greater than the radius of curvature of the posterior surface, and the distance between the centres of sphere of the anterior and posterior surfaces is greater than 5mm, preferably greater than 10 mm. By adopting the meniscus lens, the light outlet end of the dodging component can be integrally coated by utilizing the larger curvature of the meniscus lens, so that all emergent light beams are collected and enter a system light path, and the loss of light energy is reduced.

The middle section subsystem 20 is in the form of a multi-lens group and consists of M spherical lenses, wherein M is more than 1 and less than or equal to 3, and M is an integer. The spacing between the lenses in the mid-section subsystem 20 is less than 5mm, preferably 0.1-2 mm. In one embodiment, the middle subsystem 20 is composed of two lenses, namely a first biconvex lens 21 and a first biconcave lens 23, the first biconvex lens 21 is in front of the first biconcave lens 23, and the first biconcave lens 23 is in the path of the illumination beam, and the illumination beam enters the first biconvex lens after passing through the first biconvex lens. In a preferred embodiment, as shown in fig. 2, the middle subsystem 20 is composed of three lenses, and includes, in addition to the first biconvex lens 21 and the first biconcave lens 23, a convex-flat lens 22, where the convex-flat lens 22 is located between the first biconvex lens 21 and the first biconcave lens 23, and the convex-flat lens 22 needs to satisfy that the light-emitting surface is a plane or an approximate plane, where the approximate plane means that if the light-emitting surface is a spherical surface with a slight radian, the curvature radius of the spherical surface is more than 3 times the caliber, and the caliber means the diameter of the lens. The convex and flat lenses are added to ensure that the convergence effect of the middle section system on the light beams is in gentle transition, namely the diopter of the middle section system is moderate.

The rear sub-system 30 includes at least a second biconvex lens 31, and the light beam from the middle sub-system 20 is projected onto the micromirror array of the subsequent DMD after passing through the second biconvex lens 31.

In order to adapt the optical path system to the overall system configuration, the rear sub-system 30 may further include a deflection component for deflecting the optical path. The deflection assembly may have different configurations as desired. In one embodiment, as shown in fig. 3, the deflecting assembly includes only the first mirror 32, wherein the first mirror 32 is located between the middle subsystem and the second biconvex lens 31, and the light beam is deflected by 90 ° by the first mirror 32, enters the second biconvex lens 31, exits from the second biconvex lens 31, and is directly projected onto the micromirror array of the DMD. In another embodiment, as shown in fig. 4, the deflecting assembly includes a first mirror 32 and a second mirror 33, wherein the first mirror 32 is located between the middle subsystem and the second biconvex lens 31, the second mirror 33 is located behind the second biconvex lens 31, the light beam is deflected by 90 ° by the first mirror 32 and then enters the second biconvex lens 31, and exits from the second biconvex lens 31 and is deflected by 90 ° by the second mirror 33 and then is projected onto the micromirror array of the DMD. In another preferred embodiment, as shown in fig. 5, the deflecting assembly includes a first mirror 32 and a TIR prism 34, wherein the first mirror 32 is located between the midsection subsystem and the second biconvex lens 31, the TIR prism 34 is located between the second biconvex lens 31 and the DMD, the light beam is deflected by 90 ° by the first mirror 32 and then enters the second biconvex lens 31, and exits from the second biconvex lens 31 and then is deflected by 90 ° by the TIR prism 34 and then is projected to the micromirror array of the DMD.

The lens materials in the three-segment subsystem can be selected according to actual use, and commonly used optional materials comprise H-K9L, H-QK3L and Fused silica, wherein H-K9L has the advantage of low price, and Fused silica has good physical properties (good thermal conductivity and high hardness).

Further, in order to control the overall cost of the system, the lenses in each subsystem described above are spherical lenses, and the curvature radius of each lens is designed as follows: the front-section subsystem 10 is provided with an inner meniscus lens 11, the curvature radius of an object plane side is R11, the curvature radius of an image plane side is R11 and 16mm, the curvature radius of an image plane side is R12, and the curvature radius of an image plane side is 7mm and R12 and 12 mm; when the middle segment subsystem 20 comprises three lenses, the curvature radius of the object plane side of the first biconvex lens 21 is R21, 20mm < R21<60mm, the curvature radius of the image plane side is R22, and 20mm < R22<60 mm; the curvature radius of the object plane side of the convex flat lens 22 is R31, 10mm < R31<30mm, and the image plane side is a plane; the first biconcave lens 23 has an object-side radius of curvature of R41, 10mm < R41<80mm, an image-side radius of curvature of R42,6mm < R42<20 mm; the object-plane side curvature radius of the second biconvex lens 31 in the posterior sub-system 30 is R51, 100mm < R51<200mm, and the image-plane side curvature radius is R52, 60mm < R52<100 mm.

The structure form of the illumination light path system provided by the invention can be designed into different magnifications according to requirements. Specifically, in the lighting schemes with different magnifications, the focal lengths of the front-stage subsystem 10 and the back-stage subsystem 30 do not change much, the focal length of the front-stage subsystem 10 is 30-45mm, and the focal length of the back-stage subsystem 30 is 90-110mm, it should be understood that, in practical applications, the focal lengths of the front-stage subsystem 10 and the back-stage subsystem 30 can be selected within the above range, and specific values of the two are determined according to the lighting effect. The magnification of the illumination optical path system is changed by adjusting the focal length of the middle subsystem 20, and the focal length of the middle subsystem 20 has a large variation range along with the adjustment of the illumination magnification. Preferably, the focal length of the middle section subsystem 20 is approximately inversely proportional to the magnification of the illumination optical path system, i.e. the product F of the focal length of the middle section subsystem 20 and the magnification of the illumination optical path system is substantially close, and the variation range of F is preferably 150mm to 170 mm. As shown in fig. 6-a, if the magnification of the illumination optical path system is 4 times, the selectable focal length range of the middle-stage subsystem 20 is 37-43mm, preferably 40 mm; as shown in fig. 6-b, if the magnification is 5 times, the focal length of the middle subsystem 20 can be selected in the range of 30-36mm, preferably 33 mm; as shown in fig. 6-c, if the magnification is 8 times, the focal length of the middle subsystem 20 is 16-25mm, preferably 19 mm. The magnification of the system can be designed according to needs, so that the size of the dodging component can be reduced by selecting larger magnification according to the size of an actually required illumination area and the cost requirement, the processing difficulty of the dodging component is reduced, and the total cost is reduced.

Further, referring again to FIG. 2, there is a first distance D1 between the front section subsystem 10 and the middle section subsystem 20, preferably, 15mm ≦ D1 ≦ 50 mm; the middle section subsystem 20 and the rear section subsystem 30 have a larger second distance D2, preferably, D2 is more than or equal to 50mm and less than or equal to 200 mm; the third distance D3 between the rear sub-system 30 and the DMD is also larger, preferably 50mm < D3 < 300 mm. The distance between the two subsystems is the distance from the center of the last light-emitting surface of the previous subsystem to the center of the first light-in surface of the next subsystem. By setting the second distance D2 and the third distance D3 to be larger, the rear intercept of the illumination light path system is sufficient, and the deflection assembly is convenient to configure to change the light path direction, so that the requirements of different system architectures can be met. When the deflection assembly is arranged, the distance between the two subsystems is the distance through which the light beam is emitted from the previous subsystem, deflected and then reaches the next subsystem.

Table 1 shows a specific example of the lens combination of the optical system proposed in the present invention, but it should be understood that the specific parameters in this table are only one configuration selected from the above-mentioned parameters and the selected range of lens materials, and are not intended to limit the lens in the illumination system to only select the parameters in the following table.

TABLE 1

As shown in fig. 7, according to the specific design of the illumination optical path system, the range of rms of the point diagram of the illumination optical path system is between 0.05 and 0.15, and the range of 100% of the point diagram is between 0.2 and 0.4, which can ensure sharp and clear edges of the illumination light beam, and reduce the influence of defects such as stains on the light emitting surface of the dodging component on the light beam in the final projection lens.

The present invention also provides an exposure optical system including: the device comprises a light source, a light homogenizing component, an illumination light path system, a spatial light modulator and a projection optical system. The light source is preferably a semiconductor laser light source and can generate a single-wavelength light beam or generate a multi-wavelength mixed light beam; the light homogenizing component can be a light homogenizing square rod; the illumination optical path system adopts the illumination optical path system detailed in the foregoing, and preferably four or more times of magnification to reduce the size of the dodging square rod; the spatial light modulator is preferably a digital micromirror device; the projection optical system is a double telecentric optical system and is used for clearly imaging the light beam projected by the digital micromirror device, the multiplying power of the projection optical system is generally uniform in the industry, the multiplying power can also be adjusted according to the precision requirement of an exposure figure, and the size of the light beam projected from the digital micromirror device is not obviously changed after passing through the projection optical system.

Finally, it should be noted that the above description is intended to be illustrative and not exhaustive, and that the invention is not limited to the disclosed embodiments, and that various modifications and changes may be made by those skilled in the art without departing from the scope and spirit of the above examples, which should also be construed as within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the claims.