JPWO2019160781A5 - - Google Patents

Description

上式で、Ｇ_{ｓｙｍＤＯＥ}は対称位相項に相当し、Ｇ_{ａｓｙｍＤＯＥ}は非対称位相項に相当する。図３は、いくつかの実施形態に係るこの畳み込みのシミュレーション結果を示す：シミュレーションされたウエハ平面または別のターゲット１０８の平面内でのビームプロファイル３０４は、対称位相項３００と非対称位相項３０４の畳み込みの結果得られる（位相項３００の対称性および位相項３０２の非対称性は、光軸に関するものである）。図３が示すように、ターゲット１０８の平面内でのビームプロファイル３０４は、ターゲット１０８の平面内において実質的に対称（実際にはほぼ精確に対称）である。したがって、ＤＯＥは、対称位相項と非対称位相項の畳み込みの実例（インスタンス化）となって、光ビーム１０２がターゲット１０８上に斜入射角で収束されているときに、ターゲット１０８の平面内で実質的に対称なビームプロファイルを生成することができる。 The beam profile of the asymmetric DOE in the plane of the target 108 is in this case the result of the convolution of the symmetric phase term and the asymmetric phase term:

In the above equation, G _symDOE corresponds to a symmetric phase term and G _symDOE corresponds to an asymmetric phase term. FIG. 3 shows the simulation results of this convolution according to some embodiments: the beam profile 304 in the plane of the simulated wafer plane or another target 108 is a convolution of the symmetric phase term 300 and the asymmetric phase term 304. (The symmetry of phase term 300 and the asymmetry of phase term 302 are related to the optical axis). As shown in FIG. 3, the beam profile 304 in the plane of the target 108 is substantially symmetric (actually almost exactly symmetric) in the plane of the target 108. Therefore, the DOE is an example (instantiation) of the convolution of the symmetric phase term and the asymmetric phase term, and is substantially in the plane of the target 108 when the light beam 102 is converged on the target 108 at an oblique angle of incidence. A symmetrical beam profile can be generated.

The light beam is phase-modulated (eg, using the phase modulator 104) (704). In some embodiments, phase modulation is performed using a DOE, aspherical lens, rod lens, or Powell lens (706). For example, a DOE is used that produces a substantially symmetric beam profile 304 (FIG. 3) in the plane of the target by being an example (instantiation) of the convolution of the symmetric phase term 300 and the asymmetric phase term 302 (708). ). The DOE may be shaped to obtain a beam profile with a different phase for each slice of the DOE perpendicular to the plane of incidence of the light beam (eg according to FIG. 5) (710). .. The combination of the individual phases smoothes the spikes at the top of the beam.

Claims (15)

A focal lens for converging the light beam on the target at an oblique angle of incidence,
A phase modulator for substantially flattening the top of the light beam in the plane of the target when the light beam converges on the target at the oblique incident angle, the symmetric phase term. Diffractive optical element that instantiates a convolution of and an asymmetric phase term to generate a substantially symmetric beam profile in the plane of the target when the light beam converges on the target at the oblique angle of incidence. With a phase modulator equipped with (DOE) ,
A beam shaping device for an optical inspection instrument, characterized in that it is provided with. The beam shaping apparatus according to claim 1, further comprising a chuck to which the target is mounted, the focal lens is arranged between the phase modulator and the chuck in the optical path of the light beam. A beam shaping device characterized by being. The beam shaping device according to claim 2, wherein the light beam incident on the phase modulator is substantially Gaussian. The beam shaping device according to claim 2, wherein no optical element is present between the phase modulator and the focal lens. The beam shaping apparatus according to claim 1, wherein the phase modulator corresponds to an inspection track in the plane of the target when the light beam converges on the target at the oblique angle of incidence. A beam shaping apparatus, characterized in that the top of the light beam is flattened so that the change in intensity of the light beam over the width of the light beam is 10% or less. The beam shaping device according to claim 1 , wherein the cross section of the DOE perpendicular to the radial axis of the light beam is substantially wedge-shaped. The beam shaping apparatus according to claim 1 , wherein the DOE is formed so as to generate a beam profile having an individual phase with respect to an individual slice of the DOE, and the individual slice is said. A beam shaping device that is perpendicular to the plane of incidence of the light beam and that the top spikes of the beam are smoothed by combining the individual phases. The beam shaping apparatus according to claim 1, wherein the beam shaping apparatus is used.
The target is a semiconductor wafer,
The phase modulator is configured to substantially flatten the top of the light beam in a plane corresponding to the surface of the semiconductor wafer to which the light beam is converged. Shaping device. A focal lens for converging the light beam on the target at an oblique angle of incidence,
A diffractive optical element ( DOE ) for substantially flattening the top of the light beam in the plane of the target when the light beam converges on the target at the oblique incident angle. A DOE that instantiates the diffraction of a symmetric phase term and an asymmetric phase term to generate a substantially symmetric beam profile in said plane of the target .
With a chuck to which the target will be mounted,
The focal lens is arranged between the DOE and the chuck in the optical path of the light beam.
The light beam incident on the DOE is substantially Gaussian and is
A beam shaping device for an optical inspection instrument, characterized in that the cross section of the DOE perpendicular to the radial axis of the light beam is substantially wedge-shaped. Phase-modulating a light beam with a diffractive optic (DOE) that produces a substantially symmetric beam profile in the plane of the target by instantiating the convolution of the symmetric phase term and the asymmetric phase term .
Containing the light beam on the target at an oblique angle of incidence, including
The light beam phase-modulated and focused on the target at the oblique angle of incidence has a substantially flat top in the plane of the target.
A beam shaping method characterized by that. The method according to claim 10 .
The phase modulation is performed using the DOE prior to the convergence.
The method further comprises providing the light beam to the DOE, wherein the light beam provided to the DOE is substantially Gaussian. The method according to claim 10 .
The DOE is shaped to generate a beam profile with a separate phase for each individual slice of the DOE, the individual slice being perpendicular to the plane of incidence of the light beam.
A method characterized in that the spikes at the top of the beam are smoothed by combining the individual phases. A focal lens for converging the light beam on the target at an oblique angle of incidence,
To substantially flatten the top of the light beam in the plane of the target when it is positioned eccentrically with respect to the optical axis and the light beam converges on the target at the oblique angle of incidence. With a phase modulator,
Prepare,
A beam shaping device for an optical inspection instrument, wherein the phase modulator comprises an element selected from the group consisting of an aspherical lens, a rod lens, and a Powell lens. The beam shaping device according to claim 13, wherein the element is the aspherical lens. The beam shaping device according to claim 13, wherein the element is the rod lens or the Powell lens.