KR0130383B1 - Semiconductor lithography apparatus - Google Patents

Abstract

A semiconductor exposing system is provided to improve a resolution using O/2 wavelength as an exposure source. The exposure apparatus comprises: a KDP(Potassium Dihydrogen Phospate) crystal(2) for outputting O/2 wavelength; a prism(3) for splitting O and O/2 wavelengths; a filter(4) for outputting only O/2 wavelength; a first and second mirrors(5,7) for converting paths of laser light; a condense lens(8) to condense the laser light; and a reticle(9) formed in patterns for selective passing the laser light. Thereby, it is possible to increase the resolution at two times and decrease the effective focusing depth at two times.

Description

Semiconductor exposure equipment

1 is a conventional semiconductor exposure apparatus.

2 is a semiconductor exposure apparatus of the present invention.

Figure 3 (a) is a graph showing the polarization and the electric field as a function of time for the nonlinear optical case.

Figure 3 (b) is a graph showing the decomposition of polarization in the fundamental wave and the second harmonic vibration.

4 is a graph showing the upper limit of normal light and irregular light in the KDP crystal of FIG.

5 is a schematic diagram showing the refraction of light in crystalline form.

* Explanation of symbols for main parts of the drawings

1: laser device 2: KDP crystal

3: Prism 4: Filter

5: first reflector 6: fly-eye lens

7: second reflector 8: focusing lens

9: Reticle 10: Projection Lens

20: wafer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor exposure apparatus, in particular, which is adapted to increase the resolution by modulating the wavelength of a laser. Hereinafter, the prior art will be described with reference to the accompanying drawings.

1 is a block diagram of a conventional semiconductor exposure apparatus, and includes a laser device 1 for outputting laser light having a wavelength? For semiconductor exposure and a first reflector for changing the path of the laser light incident from the laser device 1. (5), the fly-eye lens 6 for dividing and outputting the laser light incident from the first reflector 5, and the second for changing the paths of a plurality of laser light that are spectroscopically incident from the fly-eye lens 6; A reflector 7, a focusing lens 8 for focusing and outputting a plurality of laser lights from the second reflecting mirror 7, and a laser beam incident from the focusing lens 8 by forming a predetermined pattern on the surface selectively A reticle 9 which passes through and outputs a constant shape, and a projection lens 10 which receives laser light passing through the reticle 9 and irradiates it on the wafer 30 without refraction.

In the conventional semiconductor exposure apparatus having the above configuration, the laser light output from the laser device 1 is sequentially passed through each lens to make light suitable for exposure, and then irradiated onto the wafer 20 to perform the exposure process.

At this time, the resolution of the exposure apparatus

Can be expressed as : Proportional constant, λ: wavelength, NA: numerical aperture of the lens.

By the way, the wavelength (λ) of the currently developed KrF laser is 848mm and the in-phase force (R) is about 0.35㎛. Therefore, the conventional exposure apparatus as described above cannot cope with the trend of high integration of semiconductor devices, and thus requires an exposure apparatus having high resolution. To this end, it is necessary to increase the numerical aperture of the lens or to develop a short wavelength laser, but at present, it is difficult to develop a large diameter lens for mexamer, and it is difficult to manufacture a short wavelength excimer laser, thereby increasing the resolution.

The present invention has been made to solve the above problems of the prior art, the wavelength of the laser The purpose is to increase the resolution of the exposure apparatus by using the wavelength of as the exposure source.

The present invention for realizing the above object is the wavelength of the laser It is characterized by selectively extracting the wavelength of and using it as the exposure source.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 shows a schematic diagram of the semiconductor exposure apparatus of the present invention, wherein the laser apparatus 1 as a KrF laser or an ArF laser that outputs a laser beam having a wavelength of λ, and the laser light output from the laser apparatus 1 Incident angle so that the light velocity of fundamental wave and 2nd harmonic vibration match Installed with a wavelength of λ A wavelength (λ) of the KDP (potassium dihydrogen phospate) crystal (or crystal) (2) that outputs a laser beam having A prism 3 separated by, and a wavelength λ and Wavelength among laser beams separated by The filter 4 passing through the bay and the filter 4 A first reflector 5 for changing the path of the laser light having a wavelength of 5, a fly-eye lens 6 for splitting and outputting the laser light incident from the first reflector 5 into a plurality of laser lights, and the fly A second reflector 7 for changing the path of the plurality of laser beams incident from the eye lens 6, a focusing lens 8 for focusing and outputting the laser beam incident from the second reflector 7, and a surface image A reticle (photomask) 9 for outputting a constant shape by selectively blocking and passing a laser light output from the focusing lens 8 and a laser beam having passed through the reticle 9 The projection lens 10 irradiates the wafer 20.

The semiconductor exposure apparatus of the present invention having the above configuration will be described below with reference to FIGS. 2 to 5.

Resolution power by laser light output from laser device 1 of FIG. The wavelength λ and the frequency υ of the laser light may be expressed as Equation (2) and (3).

In equations ② and ③,

U: nominal speed

T: cycle

k: angular wave number

w: angular frequency

Indicates.

Substituting Equation (2) into Equation (3) above can represent the wavelength of the laser beam as in Equation (4).

When the laser light passing through the KDP crystal 2 of FIG. 2 is nonlinear optical, the phases of the electric field E and the polarization P are the same as in FIG. In addition, when polarized light is decomposed into fundamental waves P (ω) and secondary harmonic vibrations P (2ω) by the KDP crystal 2, a phase difference occurs between two waves as shown in FIG. . At this time, the laser beam of wavelength λ output from the laser device 1 of FIG. 2 passes through the KDP crystal 2, and the light beam speed Ux in the X direction and the light beam speed Uy in the Y direction are shown as in FIG. , The upper quadrant of the Y axis can be represented by the circular normal beam U (ω) and the special regular beam U (2ω) with the Y axis as the long axis, and the beam speed in the X direction (Ux) and the beam speed in the Y direction ( As the vector sum of Uy), the direction of the beam speed can be indicated.

Therefore, polarization when laser light passes through the KDP crystal 2

, Where : Normal susceptibility tensor, E: electric field, Represents a higher order susceptibility tensor,

It can be expressed as Equation ⑥

Linear

Nonlinear

It can be represented as.

If the electric field E is expressed as a wave of each frequency w in equation ⑦, the second harmonic polarization

Piezoelectric crystals, such as KDP crystals (2), are represented as components and are useful for generating secondary harmonic vibrations of laser light.

The intensity of the second harmonic vibration Is indicated by Is proportional to the square of the crystal thickness, and the maximum strength is the crystal thickness. Proportional to In addition, because the crystalline is electrically anisotropic, the phase velocity has two possible values for a given propagation direction.

These two values are related to the orthogonal polarization of light, which has double reflecting.

Polarization dependence in the electric field

And simply Represented by

Common Wave Equation If there is no current density

In monochromatic plane, the wave takes the form of e ^{i (kr-wt)}

Satisfies the equation.

More generally, the principal refractive index n ₁ , n ₂ , n ₃

Is displayed. Thus, for the same reason as above, when light passes through the crystalline phase, as shown in FIG. Regarding the surface, it exhibits a refraction angle of θ ₁ Regarding the surface, a refractive angle of θ ₂ is shown. In other words, Therefore, wavelength? Changes by k. Therefore, if you combine the speed and direction of the light flux, the wavelength Phosphorus light source can be formed.

Thus, the wavelength λ of the laser light It is possible to improve the resolution twice by using the modulation as an exposure source. Therefore, the present invention as described above has a resolution Where the wavelength of the exposure source Because of Resolution is doubled in the equation, and the depth of focus of the exposure apparatus To double the numerical aperture (NA) of the lens Becomes the wavelength If you do The effective depth of focus is reduced by 2 times.

Claims (3)

A laser device that outputs a laser light having a wavelength?, And a wavelength and? A KDP crystal that outputs a phosphorus light source, and a wavelength? And A prism divided by and divided by the prism A filter for passing only a wavelength of?, A first reflector for changing a path of the laser light incident through the filter, a fly-eye lens for splitting and outputting the laser light incident from the first reflector into a plurality of laser lights; A second reflecting mirror for changing the path of the plurality of laser light incident from the fly's eye lens, a focusing lens for focusing the laser light incident from the second reflecting mirror, and a pattern for selectively passing the laser light output from the focusing lens And a projection lens configured to irradiate the laser light passing through the reticle on the wafer without refraction. The semiconductor exposure apparatus according to claim 1, wherein the laser apparatus is a KrF or ArF laser. The semiconductor exposure apparatus according to claim 1, wherein a crystal is used in addition to the KDP crystal.