KR101287608B1 - Objective lens for uv - Google Patents

Abstract

PURPOSE: An object lens for ultraviolet rays is provided to remove resolution degradation factors due to the reduction in the transmittance of ultraviolet rays by not using an adhesive trough non-bonding. CONSTITUTION: An object lens for ultraviolet rays includes a first group lens (I), a second group lens (II), and a third group lens (III). The first group lens includes a first lens having positive refractive power, a second lens having negative refractive power, a third lens having negative refractive power, and a fourth lens having positive refractive power in order from the upper surface of an image side to an object side. The second group lens includes a meniscus type fifth lens, a meniscus type sixth lens, a seventh lens having negative refractive power, a meniscus type eighth lens, a ninth lens having positive refractive power, a tenth lens having negative refractive power, an eleventh lens having positive refractive power, a twelfth lens having negative refractive power, a thirteenth lens having positive refractive power, a fourteenth lens having positive refractive power, a fifteenth lens having negative refractive power, and a sixteenth lens having positive refractive power. The third group lens includes a seventeenth lens having positive refractive power, an eighteenth lens having negative refractive power, a nineteenth lens having positive refractive power, and a twentieth lens having positive refractive power, The first lens to the twentieth lens are separately arrayed by mutual non-bonding.

Description

Objective lens for UV

The present invention relates to an objective lens for ultraviolet rays, and in particular, by minimizing the bonding between the lenses to minimize the loss and thermal deformation of the ultraviolet rays due to the bonding agent, and at the same time maximize the line width resolution for a wide wavelength range from ultraviolet to visible light At the same time, the present invention relates to an objective lens for ultraviolet light in which visual observation is optimized.

As the degree of integration of semiconductor devices increases, studies are being conducted to precisely form more complex and fine patterns on wafers. An objective lens for focusing ultraviolet rays is used in an exposure apparatus applied when forming a fine pattern of the semiconductor.

On the other hand, Korean Patent Publication No. 1988-0008037 discloses a high performance lens that can be used in the ultraviolet region in which a plurality of lenses are arranged. However, since the lens is designed to be used in the ultraviolet region, there is a problem in that the line width resolution may be degraded and the visual observation performance may be degraded when the working state is visually observed in the visible region other than the ultraviolet region.

Accordingly, there is a demand for an objective lens capable of visual observation while improving the line width resolution in the ultraviolet region and the visible ray region, and capable of suppressing deformation and refractive index changes due to deterioration caused by ultraviolet rays while increasing ultraviolet transmittance between the lenses. have.

The present invention was devised to solve the above requirements, and in particular, by not using an adhesive by non-bonding, it is possible to eliminate the factor of deterioration in resolution due to decrease in transmittance and deterioration of ultraviolet light, and visible light. An object of the present invention is to provide an ultraviolet objective lens having a structure capable of providing high resolution up to a region.

In order to achieve the above object, the objective lens for ultraviolet light according to the present invention is a first lens having positive refractive power, a second lens having negative refractive power, and a third having negative refractive power in order from the image surface on the image side to the object side direction. A first group lens including a lens and a fourth lens having positive refractive power; Meniscus fifth and sixth lenses and a seventh lens having negative refractive power, a meniscus eighth lens, a ninth lens with positive refractive power, a tenth lens with negative refractive power, an eleventh with positive refractive power A second group lens including a lens, a twelfth lens having negative refractive power, thirteenth and fourteenth lenses having positive refractive power, a fifteenth lens having negative refractive power, and a sixteenth lens having positive refractive power; And a third group lens including a seventeenth lens having a positive refractive power, an eighteenth lens having a negative refractive power, a nineteenth lens having a positive refractive power, and a twentieth lens having a positive refractive power, and including the first to twentieth lenses. Are arranged spaced apart from each other by non-bonding with each other.

Preferably, the total focal length f of the first to twentieth lenses, the focal length f1 of the first group lens, the focal length f2 of the second group lens, and the focal length f3 of the third group lens are 2 < f1 / f < 5, 5 < f2 / f < 15, and < f3 / f <

According to the objective lens for ultraviolet light according to the present invention, the lenses are arranged by non-bonding to each other to minimize absorption of the transmitted ultraviolet light, and the line width resolution is improved through aberration correction for a wide wavelength range from ultraviolet light to visible light. It provides the advantage of clearly seeing the situation during the work using ultraviolet light.

1 and 2 are cross-sectional views showing the objective lens for ultraviolet light according to the present invention,
3 is a graph of an MTF curve in which the spatial frequency of the ultraviolet objective lens of FIG. 1 is represented by the horizontal axis, the ratio is the vertical axis, and the incident angle is a parameter.
FIG. 4 is an aberration diagram illustrating spherical aberration, image curvature, and distortion of the objective lens for ultraviolet light of FIG. 1.

Hereinafter, an ultraviolet objective lens according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are cross-sectional views showing the objective lens for ultraviolet light according to the present invention. For reference, some reference numerals of the lenses of FIG. 1 are omitted in FIG. 2 to avoid the complexity of the drawings.

1 and 2, the objective lens for ultraviolet light is the first group lens I, the second group lens II, and the third group lens from the image surface IMG on the image side toward the object side OBJ. III) is provided.

The aperture 50 is provided in the second group lens II.

Hereinafter, the lens configuration of each of the first to third group lenses I, II, and III will be described.

The first group lens I is the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4, which are arranged in the image plane IMG in the direction of the object OBJ. ) The first lens L1 and the fourth lens L2 have positive refractive power, and the second and third lenses L2 and L3 have negative refractive power.

The second group lens II includes the fifth lens L5, the sixth lens L6, the seventh lens L7, and the second lens L, which are arranged in this order from the first group lens I side toward the object OBJ side. Eight lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, thirteenth lens L13, fourteenth lens L14, fifteenth The lens L15 and the sixteenth lens L16 are provided. The fifth lens L5, the sixth lens L6, and the eighth lens L8 are meniscus-type lenses, and the seventh lens L7, the tenth lens L10, the twelfth lens L12, and the eighth lens The 15th lens L15 is a concave lens having negative refractive power, and the ninth lens L9, the eleventh lens L11, the thirteenth lens L13, the fourteenth lens L14, and the sixteenth lens L16 are It is convex with positive refractive power.

The third group lens III is a biconvex type seventeenth lens L17 having positive refractive power in order from the second group lens II to the object OBJ side, and a biconvex type eighteenth lens L18 having negative refractive power. The biconvex nineteenth lens L19 having positive refractive power and the convex twentieth lens L20 having positive refractive power are provided.

Here, the 20th lens L20 corresponds to a front end lens disposed to face the object side OBJ, and the first lens L1 corresponds to a lens disposed to face the image surface IMG.

Each of the lenses L1 intrinsic L20 of the ultraviolet objective lens is arranged to be spaced apart from each other by non-bonding to a barrel (not shown), and deteriorated by ultraviolet rays due to an air gap between each lens L1 intrinsic L20. Can be suppressed.

Further, the total focal length f of the first to third group lenses I, II, and III is 4.0 mm, and the radius of curvature ri of the first lens L1 to the twentieth lens L2 is It is preferable that it is formed to satisfy the conditions.

1.00E + 17 <r1 <1.00E + 19, 30.7 <r2 <31.0, -6.3 <r3 <-6.4, -5.8 <r4 <-5.9, 4.1 <r5 <4.2, -5.6 <r6 <-5.65, 9.1 < r7 <9.2, -27.2 <r8 <-27.3, -6.5 <r9 <-6.6, -18.7 <r10 <-18.75, -10.5 <r11 <-10.6, 14.4 <r12 <14.5, 29.1 <r13 <29.5, 333.7 < r14 <333.8, 15.1 <r15 <15.2, 8.9 <r16 <8.99, 12.8 <r17 <12.9, 44.2 <r18 <44.3, -14.8 <r19 <-14.9, -11.6 <r20 <-11.7, 1.00E + 17 <r21 <1.00E + 19, 38.1 <r22 <38.2, -8.7 <r23 <-8.8, -8.3 <r24 <-8.4, 16.1 <r25 <16.2, 16.4 <r26 <16.5, -20.1 <r27 <-20.2, 44.6 < r28 <44.7, -13.3 <r29 <-13.4, -11.2 <r30 <-11.3, 15.3 <r31 <15.4, 15.4 <r32 <15.5, -81.52 <r33 <-81.6, 19.5 <r34 <19.6, -17.0 <r35 <-17.1, -16.0 <r36 <-16.1, 14.1 <r37 <14.2, 20.15 <r38 <20.25, -17.65 <r39 <-17.75, 12.75 <r40 <12.85

Here, ri (i = 1, 2, ..., n) is the radius of curvature of the i-th lens surface arranged in the direction of the object OBJ from the image surface IMG and the unit is mm.

Table 1 below shows the curvature radius, thickness or distance between lenses and refractive index (Nd) values optimized for each lens L1 to L13 constituting the optical system illustrated in FIGS. 1 and 2.

 f: 4.0mm NA: 0.4 β = 50X (magnification), W.D (Working Distance) = 12mm The curved surface (ri) Radius of curvature Thickness or distance between lenses (di) Refractive index (Nd) IMG r1 1.00E + 18 1.95 Quartz (L1) r2 30.71 0.50 r3 -6.38 1.50 CAF2 (L2) r4 -5.82 1.23 r5 4.19 1.50 CAF2 (L3) r6 -5.61 1.65 r7 9.12 2.79 Quartz (L4) r8 -27.23 12.13 r9 -6.51 3.02 CAF2 (L5) r10 -18.71 0.50 r11 -10.55 2.23 Quartz (L6) r12 14.41 2.37 r13 29.4 1.50 Quartz (L7) r14 337.74 0.50 r15 15.15 2.31 CAF2 (L8) r16 8.98 1.36 r17 12.84 2.72 CAF2 (L9) r18 44.25 0.71 r19 -14.88 1.50 Quartz (L10) r20 -11.64 2.09 r21 1.00E + 18 3.69 CAF2 (L11) r22 38.13 0.54 r23 -8.74 1.50 Quartz (L12) r24 -8.3 0.50 r25 16.16 3.76 CAF2 (L13) r26 16.45 0.50 r27 -20.11 3.73 CAF2 (L14) r28 44.68 0.78 r29 -13.32 1.50 Quartz (L15) r30 -11.23 0.50 r31 15.34 3.46 CAF2 (L16) r32 15.48 0.50 r33 -81.57 4.46 CAF2 (L17) r34 19.57 0.50 r35 -17.04 1.50 Quartz (L18) r36 -16.1 0.97 r37 14.14 3.99 CAF2 (L19) r38 20.2 0.50 r39 -17.7 3.06 CAF2 (L20) r40 12.79 12.01 OBJ ∞

Here, the refractive index of the lens material is shown in Table 2 below.

material 550 nm 486 nm 266 nm Quartz 1.459880 1.463106 1.500375 CAF2 1.434822 1.437021 1.462068

In addition, the separation distance between the tenth lens (L10) and the aperture 50 is applied to 0.5mm, the total focal length f of the first to 20th lens and the focal length f1, the first group lens (I) The focal length f2 of the two-group lens (II) and the focal length f3 of the third group lens (III)

2 <f1 / f <5,

5 <f2 / f <15,

It is formed to satisfy the condition of 2 <f3 / f <5.

An aberration diagram showing spherical aberration, image curvature, and distortion is shown in FIG.

As can be seen from Figures 3 and 4 it can be seen that the excellent performance characteristics for the ultraviolet region.

4 shows aberration, top curvature, and percent distortion for light having wavelengths of 550.0 nm, 486.0 nm, and 266.0 nm for the 0.25 upper, 0.50 upper, 0.75 upper, and 1.00 upper surfaces, respectively.

Such an ultraviolet objective lens provides high resolution not only in the ultraviolet region but also in the visible region, so that, for example, when applied to an exposure apparatus using the ultraviolet ray, the operator can visually observe it when working with the ultraviolet ray.

I: first lens group II: second lens group
III: Third lens group

Claims (3)

In the objective lens for ultraviolet rays,
A first group lens comprising a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a negative refractive power, and a fourth lens having a positive refractive power, in order from the image surface on the image side toward the object side; ;
Meniscus fifth and sixth lenses and a seventh lens having negative refractive power, a meniscus eighth lens, a ninth lens with positive refractive power, a tenth lens with negative refractive power, an eleventh with positive refractive power A second group lens including a lens, a twelfth lens having negative refractive power, thirteenth and fourteenth lenses having positive refractive power, a fifteenth lens having negative refractive power, and a sixteenth lens having positive refractive power;
And a third group lens including a seventeenth lens having positive refractive power, an eighteenth lens having negative refractive power, a nineteenth lens having positive refractive power, and a twentieth lens having positive refractive power; and
The objective lens for ultraviolet rays, characterized in that the first lens to the twentieth lens are arranged to be spaced apart from each other by non-bonding. The method of claim 1, wherein the total focal length f of the first to twentieth lenses, the focal length f1 of the first group lens, the focal length f2 of the second group lens, and the focal length f3 of the third group lens silver
An objective lens for ultraviolet rays, characterized in that it is formed to satisfy the conditions 2 <f1 / f <5, 5 <f2 / f <15, and 2 <f3 / f <5. The method of claim 2, wherein the total focal length f is 4.0mm,
The radius of curvature (ri) of the twentieth lens from the first lens satisfies the following conditions.
1.00E + 17 <r1 <1.00E + 19, 30.7 <r2 <31.0, -6.3 <r3 <-6.4, -5.8 <r4 <-5.9, 4.1 <r5 <4.2, -5.6 <r6 <-5.65, 9.1 < r7 <9.2, -27.2 <r8 <-27.3, -6.5 <r9 <-6.6, -18.7 <r10 <-18.75, -10.5 <r11 <-10.6, 14.4 <r12 <14.5, 29.1 <r13 <29.5, 333.7 < r14 <333.8, 15.1 <r15 <15.2, 8.9 <r16 <8.99, 12.8 <r17 <12.9, 44.2 <r18 <44.3, -14.8 <r19 <-14.9, -11.6 <r20 <-11.7, 1.00E + 17 <r21 <1.00E + 19, 38.1 <r22 <38.2, -8.7 <r23 <-8.8, -8.3 <r24 <-8.4, 16.1 <r25 <16.2, 16.4 <r26 <16.5, -20.1 <r27 <-20.2, 44.6 < r28 <44.7, -13.3 <r29 <-13.4, -11.2 <r30 <-11.3, 15.3 <r31 <15.4, 15.4 <r32 <15.5, -81.52 <r33 <-81.6, 19.5 <r34 <19.6, -17.0 <r35 <-17.1, -16.0 <r36 <-16.1, 14.1 <r37 <14.2, 20.15 <r38 <20.25, -17.65 <r39 <-17.75, 12.75 <r40 <12.85
Where ri (i = 1, 2, ..., n) is the radius of curvature of the i-th lens surface from the object and the unit is mm.

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