TWI682249B - Projection objective optical system and lithography machine - Google Patents

Abstract

The invention provides a projection objective optical system and a lithography machine for imaging graphics on an object plane to an image plane. The projection objective optical system includes, in order from the object plane side along its optical axis, a negative focus First lens group; second lens group with positive power; third lens group with positive power; aperture stop; fourth lens group with positive power; the fourth lens group and the third The lens group is symmetric with respect to the aperture stop; the fifth lens group with positive power; the fifth lens group and the second lens group are symmetric with respect to the aperture stop; and the sixth lens group with negative power; The sixth lens group and the first lens group are symmetrical with respect to the aperture stop. The present invention provides a large-field projection objective optical system suitable for three-line wavelengths of g, h, and i, while ensuring imaging image quality, and significantly improving exposure yield.

Description

Projection objective optical system and lithography machine

The invention relates to the technical field of semiconductor manufacturing, in particular to a projection objective optical system and a lithography machine of a lithography equipment.

The current rapid development in the field of semiconductor packaging places higher and higher requirements on lithographic projection objectives for manufacturing integrated circuit wafers. Not only is the resolution and imaging quality of projection lithography objectives continuously improved, but also the yield high demand. Among them, increasing the exposure field of view of the projection objective is the most direct and effective way to increase productivity.

The US patent US7697511B2 discloses a -1x magnification, which is suitable for the projection objective lens structure with three-line wavelengths of g, h and i. The maximum field of view of the objective lens is only 42mm, so the productivity is limited.

Japanese Patent JP2000199850 discloses a lithography lens suitable only for g-line and h-line, which has a numerical aperture of 0.1, an image-side half field of view of 117 mm, and contains 38 lenses. The objective lens has a complicated structure and high manufacturing cost, and the applicable spectrum is only g-line and h-line.

The purpose of the present invention is to overcome the shortcomings in the conventional technology, and to propose a large field of view objective optical system used in the field of semiconductor lithography, which is suitable for the three-line wavelengths of g, h, and i, while ensuring the imaging quality and significantly increasing the exposure Yield.

To achieve the above object, the present invention provides a projection objective optical system for imaging graphics on an object plane to an image plane. The projection objective optical system includes, in order from the object plane side along its optical axis, a negative focus The first lens group of degrees; the second lens group with positive power; A third lens group having positive power; an aperture stop; a fourth lens group having positive power, the fourth lens group and the third lens group are symmetrical with respect to the aperture stop; having positive power A fifth lens group, the fifth lens group and the second lens group are symmetrical with respect to the aperture stop; and a sixth lens group having negative power, the sixth lens group and the first A lens group is symmetrical with respect to the aperture stop.

Preferably, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group and the sixth lens group satisfy the following relationship : -0.5<f2/f1<-0.2; -0.5<f3/f1<-0.2; -0.5<f4/f6<-0.2; -0.5<f5/f6<-0.2; where: f1 is the first lens Focal length of the group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, f4 is the focal length of the fourth lens group, f5 is the focal length of the fifth lens group, and f6 is The focal length of the sixth lens group.

Preferably, the first lens group includes at least one biconcave lens.

Preferably, the second lens group includes a sub-lens group having positive power and a sub-lens group having negative power, and the second lens group includes at least two biconcave lenses.

Preferably, the sub-lens group with positive refractive power includes a first meniscus positive lens, a first biconvex positive lens, and a second meniscus positive lens arranged in sequence along the optical axis of the projection objective optical system A lens, the sub-lens group with negative power includes a first meniscus negative lens, a second biconvex positive lens, and a first biconcave negative lens that are sequentially arranged along the optical axis of the projection objective optical system And a second double concave negative lens.

Preferably, the second lens group includes at least two biconcave lenses of the same material, and the material of the biconcave lens is SILICA, SFSL5Y or BSL7Y.

Preferably, the third lens group includes a third biconvex positive lens, a third biconcave negative lens, a fourth biconvex positive lens, and a second arranged in sequence along the optical axis of the projection objective optical system Meniscus negative lens and fifth biconvex positive lens.

Preferably, the third lens group includes at least two lenses made of high-dispersion material, and the high-dispersion material is CAF2, NFK51A or NIGS4786.

0.14。 Preferably, the object-side numerical aperture of the projection objective optical system

0.14.

67.5mm。 Preferably, the image side half field of view of the projection objective optical system

67.5mm.

Preferably, the magnification of the projection objective optical system is -1x.

26片。 Preferably, the lenses used in the projection objective optical system are all spherical lenses, and the number of the lenses

26 tablets.

1200mm，物方遠心和像方遠心均<6.5mrad，物距和像距均

50mm。 Preferably, the object image distance of the projection objective optical system

1200mm, object-side telecentricity and image-side telecentricity are both <6.5mrad, object distance and image distance are both

50mm.

Preferably, the projection objective optical system is suitable for the three-line wavelengths of g, h, and i.

Correspondingly, the present invention also provides a lithography machine, the lithography machine includes the above-mentioned projection objective optical system.

In summary, the present invention provides a large-field projection objective optical system suitable for the three-line wavelengths of g, h, and i, while ensuring the imaging quality and significantly increasing the exposure yield.

0.14，放大倍率為-1x，最大像方半視場為67.5mm，具有較高的曝光產率。 Further, the object-side numerical aperture of the projection objective optical system provided by the present invention

0.14, the magnification is -1x, the maximum image side half field of view is 67.5mm, and it has a high exposure yield.

Further, the projection objective optical system provided by the present invention adopts a double telecentric structure, both the object-side telecentricity and the image-side telecentricity are less than 6.5mrad, and the object-image-distance is not more than 1200mm, which reduces the sensitivity of the objective lens to the minute concave and convex defects on the mask surface At the same time make the optical system structure more compact It has good achromatic effect and small aberration of monochromatic wave. It guarantees the imaging quality under the condition of realizing a large field of view of 67.5mm in the three-line wavelength of g, h and i.

Further, the object distance and the image distance of the projection objective optical system provided by the present invention are both greater than 50 mm, and have a sufficient mechanical distance to facilitate mechanical assembly and process realization. At the same time, the number of lenses in the projection objective optical system is not more than 26, and they are all spherical lenses, which reduces the structural complexity of the objective lens, improves the transmittance of the objective lens, significantly reduces the cost of the objective lens, and further improves the exposure yield.

G1‧‧‧First lens group

1‧‧‧Double concave negative lens

G2‧‧‧Second lens group

2‧‧‧The first meniscus lens

3‧‧‧ double convex positive lens

4‧‧‧Second meniscus positive lens

5‧‧‧Negative meniscus lens

6‧‧‧ double convex positive lens

7‧‧‧The first double concave negative lens

8‧‧‧Second double concave negative lens

G3‧‧‧third lens group

9‧‧‧First biconvex positive lens

10‧‧‧Double concave negative lens

11‧‧‧Second biconvex positive lens

12‧‧‧Negative meniscus lens

13‧‧‧third biconvex positive lens

G4‧‧‧ fourth lens group

14‧‧‧First biconvex positive lens

15‧‧‧Negative meniscus lens

16‧‧‧Second biconvex positive lens

17‧‧‧Double concave negative lens

18‧‧‧third biconvex positive lens

G5‧‧‧fifth lens group

19‧‧‧The first double concave negative lens

20‧‧‧Second double concave negative lens

21‧‧‧ double convex positive lens

22‧‧‧Negative meniscus lens

23‧‧‧First meniscus lens

24‧‧‧ double convex positive lens

25‧‧‧Second meniscus positive lens

G6‧‧‧Sixth lens group

26‧‧‧Double concave negative lens

27‧‧‧like

1 is a schematic structural view of a projection objective optical system provided by an embodiment of the invention; FIG. 2 is a telecentric curve of a projection objective optical system provided by an embodiment of the invention; FIG. 3 is a projection provided by an embodiment of the invention Aberration diagram of light rays of the objective optical system; FIG. 4 is a distortion diagram of the projection objective optical system provided by an embodiment of the present invention.

In order to make the content of the present invention more clear and understandable, the content of the present invention will be further described below in conjunction with the accompanying drawings of the description. Of course, the present invention is not limited to this specific embodiment, and general replacements well known to those of ordinary skill in the art are also covered by the protection scope of the present invention.

Secondly, the present invention is described in detail using schematic diagrams. When describing the examples of the present invention in detail, the schematic diagrams are not partially enlarged in accordance with the general scale, and should not be regarded as a limitation of the present invention.

In addition, the ordinal numbers "first", "second", etc. used in the embodiments of the present invention are only for the convenience of description and do not play any limiting role, for example, "first lenticular lens ", "Second meniscus positive lens", "First biconcave negative lens"... etc.

The invention provides a large field of view lithography projection objective suitable for the three-line wavelengths of g, h, and i, while ensuring the imaging image quality, and significantly improving the exposure yield.

The specific embodiments of the present invention are described in detail below with reference to the drawings.

FIG. 1 is a schematic structural diagram of an embodiment of a projection objective optical system of the present invention. In this embodiment, 26 lenses are used, and all lenses are spherical lenses. The spectrum used in this embodiment is a simplified g, h, i three-line mercury lamp spectrum, and the specific spectral weight distribution is shown in Table 1. In this embodiment, the projection objective optical system starts from the object plane, and in order from the beam incident direction is the object plane, the first lens group G1, the second lens group G2, the third lens group G3, the aperture stop, and the fourth lens group G4 , The fifth lens group G5, the sixth lens group G6, and the image plane 27. among them:

The first lens group G1 has negative refractive power. The first lens group G1 includes at least one double-concave lens. In this embodiment, the first lens group G1 is composed of one lens, which is a double-concave negative lens 1.

The second lens group G2 has positive power, and the second lens group G2 includes a sub-lens group G2-1 having positive power and a sub-lens group G2-2 having negative power, and the second lens group G2 At least two biconcave lenses. The sub-lens group G2-1 with positive power includes a first meniscus positive lens 2, a biconvex positive lens 3, and a second meniscus positive lens arranged in this order along the optical axis of the projection objective optical system 4. The sub-lens group G2-2 with negative power includes a meniscus negative lens 5, a biconvex positive lens 6, and a first biconcave negative lens arranged in sequence along the optical axis of the projection objective optical system The lens 7 and the second double concave negative lens 8.

The third lens group G3 has a positive power and is composed of 5 lenses, which are respectively a first biconvex positive lens 9, a double concave negative lens 10, and a second arranged in sequence along the optical axis of the projection objective optical system A biconvex positive lens 11, a meniscus negative lens 12, and a third biconvex positive lens 13.

The fourth lens group G4 has positive refractive power and is symmetrical to the third lens group G3 with respect to the aperture stop, and is composed of 5 lenses, which are respectively the first pair arranged sequentially along the optical axis of the projection objective optical system Convex positive lens 14, negative meniscus lens 15, second double convex positive lens 16, double concave negative lens 17, and third double convex positive lens 18.

The fifth lens group G5 has positive refractive power and is symmetrical to the second lens group G2 with respect to the aperture stop. The fifth lens group G5 also includes at least two biconcave lenses. In this embodiment, the fifth lens group G5 includes a sub-lens group G5-1 having negative power and a sub-transparent lens having positive power Mirror group G5-2, the sub-lens group G5-1 and the sub-lens group G2-2 are symmetric with respect to the aperture stop, the sub-lens group G5-2 and the sub-lens group G2-1 are relative to the aperture The diaphragm is symmetrical. The sub-lens group G5-1 with negative power includes a first double-concave negative lens 19, a second double-concave negative lens 20, and a double-convex positive lens, which are sequentially arranged along the optical axis of the projection objective optical system A lens 21 and a meniscus negative lens 22, the sub-lens group G5-2 with positive power includes a first meniscus positive lens 23 and a biconvex positive lens arranged in sequence along the optical axis of the projection objective optical system The lens 24 and the second meniscus positive lens 25.

The sixth lens group G6 has negative refractive power and is symmetrical to the first lens group G1 with respect to the aperture stop, is composed of one lens, and is a double concave negative lens 26.

The second lens group G2 includes at least two double-concave lenses of the same material, such as a first double-concave negative lens 7 and a second double-concave negative lens 8. Similarly, the second lens group G2 is opposite to the aperture stop The symmetric fifth lens group G5 also includes at least two double concave lenses of the same material, such as a first double concave negative lens 19 and a second double concave negative lens 20. The material of the biconcave lens is SILICA, SFSL5Y or BSL7Y, but it is not limited thereto.

The third lens group G3 includes at least two lenses made of a high-dispersion material. Similarly, the fourth lens group G4 symmetrical to the third lens group G3 with respect to the aperture stop also includes at least two lenses Lenses made of highly dispersion materials. The high dispersion material is CAF2, NFK51A or NIGS4786, but it is not limited thereto.

The focal lengths of the first lens group G1, the second lens group G2, and the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 satisfy the following relationship: -0.5 <f2/f1<-0.2 -0.5<f3/f1<-0.2 -0.5<f4/f6<-0.2 -0.5<f5/f6<-0.2 Where: f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, f4 is the focal length of the fourth lens group, f5 is the focal length of the fifth lens group, and f6 is the first The focal length of the six lens group.

Preferably, f2/f1=-0.35 and f3/f1=-0.45.

Preferably, f4/f6=-0.45 and f5/f6=-0.35.

Table 2 lists the specific design values of the projection objective optical system of the embodiment, where the positive radius R represents the center of curvature of the lens surface near the image side, and the negative radius R represents the center of curvature of the lens surface near the object side . 1.00E+18 means the surface is flat. In the table, OBJ stands for the object plane, STOP stands for the aperture stop, and IMA stands for the image plane. In the table, the material column "AIR" represents the air gap between the lens and the lens, the filling gas is air, and the non-AIR material in the material column refers to the specific lens material type. The full aperture column refers to the maximum clear aperture (diameter) of a lens surface. The thickness of the optical element or the interval between the two optical elements refers to the axial distance from this surface to the next surface, and all dimensions are in millimeters (mm).

0.14，像方半視場

67.5mm，較大的曝光視場使曝光產率明顯提高。 較佳地，本實施例中投影物鏡光學系統提供的是一直徑為135mm的圓形視場，物方數值孔徑為0.14。 The magnification of the projection objective optical system provided by the present invention is -1x, and the object side numerical aperture

0.14, half field of view

67.5mm, the larger exposure field of view significantly increases the exposure yield. Preferably, the projection objective optical system in this embodiment provides a circular field of view with a diameter of 135 mm and an object-side numerical aperture of 0.14.

The projection objective optical system provided by the invention adopts a bi-telecentric structure, and the object-side telecentricity and the image-side telecentricity are both <6.5 mrad. The sensitivity of the objective lens to the minute concave and convex defects on the mask surface is reduced, and the imaging quality of the mask surface is ensured. Preferably, the object-side telecentricity of the projection objective optical system of this embodiment is 0, and the image-side telecentricity is 6.35 mrad.

1200mm，光學系統結構緊湊，消色差效果較好，單色波像差較小，能夠保證投影物鏡光學系統具有較好的成像品質。較佳地，本實施例中投影物鏡光學系統的物像方距離為1200mm。 Object image distance of projection objective optical system provided by the invention

1200mm, compact optical system structure, good achromatic effect, small monochromatic wave aberration, can guarantee the projection objective optical system has good imaging quality. Preferably, the object image side distance of the projection objective optical system in this embodiment is 1200 mm.

50mm，具有足夠的機械距離，便於機械裝配和製程實現。較佳地，本實施例中投影物鏡光學系統的物距和像距均為57mm。 The object distance and image distance of the projection objective optical system provided by the present invention are both

50mm, with sufficient mechanical distance, easy for mechanical assembly and manufacturing process. Preferably, the object distance and image distance of the projection objective optical system in this embodiment are both 57 mm.

The number of lenses of the projection objective optical system provided by the present invention is not more than 26, and they are all spherical lenses, which reduces the structural complexity of the objective lens, improves the transmittance of the objective lens, significantly reduces the cost of the objective lens, and increases the exposure yield. Preferably, the number of lenses in the projection objective optical system of this embodiment is 26, and they are all spherical lenses.

The projection objective optical system provided by the present invention is suitable for g (365 nm), h (405 nm), and i (435 nm) three-line wavelengths, and is suitable for a wide-spectrum ultraviolet mercury lamp light source.

2 is a telecentric curve (Object & Image Telecentricity) of the projection objective optical system provided in this embodiment, where the abscissa is the height of the object half field of view (Object Height (mm)), 0 represents the center of the object, and the ordinate Represents the size of the telecentricity (mrad) under a certain object field of view. It can be seen from the curve that when the height of the object field of view is about 40 mm, the maximum telecentricity is 6.35 mrad, indicating that the telecentricity of the objective lens has been well corrected.

FIG. 3 is a ray aberration diagram (Ray Aberration (millimeters)) of the projection objective optical system provided in this embodiment. The five-line diagram from bottom to top represents the different heights in turn. The aberration distribution of the object field of view point at the pupil. The two graphs in each row represent the distribution of pupil meridian and sagittal aberration. The abscissa of each graph represents the height on the pupil, where the center point represents the light. For the pupil center, the ordinate represents the aberration magnitude, and the three curves represent the aberration curves at three wavelengths of 365 nm, 405 nm, and 435 nm, respectively. It can be seen from the figure that the maximum aberration of each field of view is less than 0.001938mm, indicating that the wave aberration of the objective lens is well corrected, and the chromatic aberration between the wavelengths of 365nm, 405nm, and 435nm is well corrected.

4 is a distortion diagram (Distortion) of the projection objective of the embodiment, wherein the ordinate represents the height of the object half field of view, and the abscissa represents the distortion value. It can be seen from the figure that the distortion of each object half field point is basically 0, The objective lens distortion is basically corrected to 0.

The invention also provides a lithography machine including the above-mentioned projection objective optical system.

0.14，放大倍率為-1x，最大像方半視場為67.5mm，具有較高的曝光產率。 In summary, the present invention provides a large-field projection objective optical system suitable for the three-line wavelengths of g, h, and i. Object-side numerical aperture

0.14, the magnification is -1x, the maximum image side half field of view is 67.5mm, and it has a high exposure yield.

The projection objective optical system provided by the invention adopts a double telecentric structure, the object-side telecentricity and the image-side telecentricity are both less than 6.5mrad, and the object-image-distance is not more than 1200mm, which reduces the sensitivity of the objective lens to the minute concave and convex defects on the mask surface The system structure is more compact, and has better achromatic effect and smaller monochromatic wave aberration. Under the condition of realizing a large field of view of 67.5mm in three-line wavelength of g, h and i, the imaging quality is guaranteed.

The object distance and the image distance of the projection objective optical system provided by the present invention are both greater than 50 mm, and have sufficient mechanical distance, which is convenient for mechanical assembly and manufacturing process. At the same time, the number of lenses in the projection objective optical system is not more than 26, and they are all spherical lenses, which reduces the structural complexity of the objective lens, improves the transmittance of the objective lens, significantly reduces the cost of the objective lens, and further improves the exposure yield.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. Any person with ordinary knowledge in the technical field without departing from the technical solutions of the present invention Within the scope, any form of equivalent replacement or modification of the technical solutions and technical contents disclosed in the present invention is within the scope of the present invention without departing from the technical solutions of the present invention.

G1‧‧‧First lens group

1‧‧‧Double concave negative lens

G2‧‧‧Second lens group

2‧‧‧The first meniscus lens

3‧‧‧ double convex positive lens

4‧‧‧Second meniscus positive lens

5‧‧‧Negative meniscus lens

6‧‧‧ double convex positive lens

7‧‧‧The first double concave negative lens

8‧‧‧Second double concave negative lens

G3‧‧‧third lens group

9‧‧‧First biconvex positive lens

10‧‧‧Double concave negative lens

11‧‧‧Second biconvex positive lens

12‧‧‧Negative meniscus lens

13‧‧‧third biconvex positive lens

G4‧‧‧ fourth lens group

14‧‧‧First biconvex positive lens

15‧‧‧Negative meniscus lens

16‧‧‧Second biconvex positive lens

17‧‧‧Double concave negative lens

18‧‧‧third biconvex positive lens

G5‧‧‧fifth lens group

19‧‧‧The first double concave negative lens

20‧‧‧Second double concave negative lens

21‧‧‧ double convex positive lens

22‧‧‧Negative meniscus lens

23‧‧‧First meniscus lens

24‧‧‧ double convex positive lens

25‧‧‧Second meniscus positive lens

G6‧‧‧Sixth lens group

26‧‧‧Double concave negative lens

27‧‧‧like

Claims (14)

A projection objective optical system for imaging a graphic on an object plane to an image plane, wherein the projection objective optical system includes, in order from the object plane side along its optical axis direction, a first lens group having negative light Power; a second lens group having positive power, and the second lens group includes a sub-lens group having positive power and a sub-lens group having negative power, the second lens group includes at least two lenses A biconcave lens; a third lens group with positive power; an aperture stop; a fourth lens group with positive power, the fourth lens group and the third lens group are symmetrical with respect to the aperture stop A fifth lens group having positive power, the fifth lens group and the second lens group are symmetrical with respect to the aperture stop; and a sixth lens group having negative power, the sixth lens The group and the first lens group are symmetrical with respect to the aperture stop. The projection objective optical system according to item 1 of the patent application range, wherein the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth The lens group satisfies the following relationship: -0.5<f2/f1<-0.2; -0.5<f3/f1<-0.2; -0.5<f4/f6<-0.2; -0.5<f5/f6<-0.2; where, f1 Is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, f4 is the focal length of the fourth lens group, f5 is the focal length of the fifth lens group, f6 Is the focal length of the sixth lens group. The projection objective optical system according to item 1 of the patent application scope, wherein the first lens group includes at least one biconcave lens. The projection objective optical system according to item 1 of the patent application range, wherein the sub-lens group with positive power includes a first meniscus positive lens arranged in sequence along the optical axis of the projection objective optical system , A first biconvex positive lens, a second meniscus positive lens, the sub-lens group with negative power includes a first meniscus negative arranged in sequence along the optical axis of the projection objective optical system A lens, a second double convex positive lens, a first double concave negative lens and a second double concave negative lens. The projection objective optical system according to Item 1 of the patent application range, wherein the second lens group includes at least two biconcave lenses of the same material, and the biconcave lenses are made of SILICA, SFSL5Y, or BSL7Y. The projection objective optical system according to item 1 of the patent application range, wherein the third lens group includes a third biconvex positive lens and a third double lens arranged in sequence along the optical axis of the projection objective optical system A concave negative lens, a fourth biconvex positive lens, a second meniscus negative lens and a fifth biconvex positive lens. The projection objective optical system according to item 1 of the patent application range, wherein the third lens group includes at least two lenses made of a high-dispersion material, the high-dispersion material being CAF2, NFK51A, or NIGS4786. The projection objective optical system according to item 1 of the patent application scope, wherein the object-side numerical aperture of the projection objective optical system

0.14. The projection objective optical system according to item 1 of the patent application scope, wherein the image side half field of view of the projection objective optical system

67.5mm. The projection objective optical system according to item 1 of the patent application range, wherein the magnification of the projection objective optical system is -1x. The projection objective optical system according to item 1 of the patent application scope, wherein the lenses used in the projection objective optical system are all spherical lenses, and the number of the lenses

26 tablets. The projection objective optical system according to item 1 of the patent application scope, wherein the object image distance of the projection objective optical system

1200mm, object-side telecentricity and image-side telecentricity are both <6.5mrad, object distance and image distance are both

50mm. The projection objective optical system according to any one of claims 1 to 12, wherein the projection objective optical system is suitable for the three-line wavelengths of g, h, and i. A lithography machine comprising the projection objective optical system according to any one of the items 13 of the patent application scope.

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