KR100601619B1 - Method for measuring optical properties of medium having thin-film stack illumated by focused field and method for setting thickness of optical recording medium - Google Patents

Abstract

Disclosed are a method of measuring optical characteristics of a thin film laminated medium and a method of setting a thickness of an optical recording medium that change with the numerical aperture of focused light.

를 산출하는 단계와; 웨이브 벡터

와 전기장

의 벡터곱을 고체각

에 대해 적분한 형태로 표현되는 자기장

를 산출하는 단계와; 전기장

와 자기장 를 벡터곱하고, 그 값의 실수부를 취한 형태로 표현되는 포인팅벡터

를 산출하는 단계와; 상기 매체의 j번째 층의 반사율(R), 투과율(T) 및 흡수율(A) 각각을 하기의 수학식을 만족하는 형태의 포인팅 벡터로 나타내는 단계;를 포함하는 것을 특징으로 한다. 또한, j번째 층에 대한 소망하는 R, T, A에 적합한 포인팅벡터, 자기장 및 전기장을 산출하고, 전기장을 결정하는 변수인 매체의 j번째 층의 두께를 설정할 수 있다.The method of measuring the optical properties of the disclosed thin film laminated media and the method of setting the thickness of the optical recording medium for an ultra-resolution optical recording / reproducing apparatus includes

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; And representing each of the reflectance (R), transmittance (T), and absorbance (A) of the j-th layer of the medium as a pointing vector satisfying the following equation. Further, a pointing vector, a magnetic field, and an electric field suitable for the desired R, T, and A for the jth layer can be calculated, and the thickness of the jth layer of the medium, which is a variable for determining the electric field, can be set.

Equation

,

,

,

,

Description

Method for measuring optical properties of medium having thin-film stack illumated by focused field and method for setting thickness of optical recording medium}

1 is a flowchart illustrating a method for measuring optical characteristics of a thin film laminated media according to the present invention.

2 is a schematic illustration of an optical arrangement of an optical system capable of focusing light onto a thin film stack.

3 shows a three-layer thin film stacked medium.

4 is a graph showing the change in energy flow rate according to the change in energy flow rate according to the change in depth from the incident surface.

FIG. 5 is a graph showing changes in R, T and A with increasing numerical aperture in the numerical aperture of 0 to 1.0 of the thin film-laminated media shown in FIG.

FIG. 6 is a graph showing a change in reflectance according to incident angles for s and p waves of the thin film-laminated media shown in FIG. 3. FIG.

층의 두께에 따른 반사율 변화를 나타낸 그래프.FIG. 7 is an upper portion of the thin film stacked media shown in FIG.

Graph showing change in reflectance with thickness of layer.

FIG. 8 is a schematic illustration of a solid immersion lens (SIL) and thin film stacked media; FIG.

FIG. 9 is a graph showing changes in R, T, and A with increasing numerical aperture in the numerical aperture of 0 to 1.5 in FIG. 8; FIG.

FIG. 10 is a graph illustrating changes in reflectances of s and p waves according to incident angles of plane waves incident on a thin film stack composed of an incidence medium, an air gap, and the thin film stacked medium of FIG.

층에서 개구수 0.6, 0.85 및 1.2 각각에 대하여 빔의 중심으로부터의 거리 변화에 따른 에너지 유동율 변화를 나타낸 그래프.11 is of FIG. 3

Graph showing energy flow rate change with distance from center of beam for numerical apertures 0.6, 0.85 and 1.2 respectively in the layer.

12 is a view showing an example of an optical recording medium for explaining the thickness setting method of the optical recording medium according to the present invention.

FIG. 13 is a graph illustrating changes in reflectances of s-wave and p-wave according to the change of the incident angle in the optical recording medium shown in FIG.

FIG. 14 is a graph showing a change in reflectance according to a change in the numerical aperture of incident light in the optical recording medium shown in FIG. 12; FIG.

FIG. 15 is a graph showing a change in reflectance according to a change in thickness of the first dielectric layer positioned on the side where light is incident on the optical recording medium shown in FIG. 12; FIG.

R)의 변화를 나타낸 그래프.FIG. 16 illustrates a difference in reflectance which is a difference between crystalline reflectivity Rc and amorphous reflectance Ra according to a change in thickness of the first dielectric layer in the optical recording medium shown in FIG.

Graph showing change in R).

FIG. 17 is a graph showing the change in the crystalline absorption ratio (Ac / Aa) to the amorphous absorption rate according to the thickness change of the first dielectric layer in the optical recording medium shown in FIG.

FIG. 18 is a graph illustrating a change in reflectance according to an air gap change in the optical recording medium shown in FIG. 12; FIG.

R)의 변화를 나타낸 그래프.FIG. 19 illustrates a difference in reflectance which is a difference between crystalline reflectance Rc and amorphous reflectance Ra according to air gap change in the optical recording medium shown in FIG.

Graph showing change in R).

FIG. 20 is a graph showing the change of the crystalline absorption ratio (Ac / Aa) to the amorphous absorption rate according to the air gap change in the optical recording medium shown in FIG. 12; FIG.

<Description of Symbols for Main Parts of Drawings>

L ... Incident light R ... Reflectance T ... Transmittance

A ... absorption rate 5 ... solid-impregnated lens 10 ... thin laminated media

11 Substrate 13 Lower layer Si ₃ N ₄ film 15 a-Si film

17 top layer Si ₃ N ₄ film 21 substrate 22 first dielectric layer

23 ... recording film 24 ... second dielectric layer 25 ... reflective film

The present invention relates to a method for measuring the optical characteristics of a thin film-laminated media that changes according to the numerical aperture of focused light and a method for setting the thickness of an optical recording medium to have a reflectance, transmittance, and absorption ratio suitable for a set numerical aperture of an optical recording / reproducing optical system.

In recent years, lenses having a high numerical aperture (N.A.) have been widely used in various fields requiring high resolution. That is, in the optical recording field, a lens having a numerical aperture of 0.8 or a solid immersion lens (SIL) of 1.0 or more or a solid immersion mirror (SIM) for reducing the diameter of the light spot formed on the recording medium for high capacity data recording. Lens) is used. In the field of microlithography, a lens having a small and high numerical aperture is used to be suitable for miniaturization of an etching pattern.

On the other hand, the light focused by the lens and condensed on a thin film stacking medium having a multilayer thin film structure such as an optical recording medium has a larger incident angle as the numerical aperture of the lens increases. Here, when looking at the reflectance (R), transmittance (T) and absorption (A) in the medium, the plane wave is incident perpendicular to the plane of incidence of the medium due to the angle of incidence, and the light is incident at a predetermined angle of incidence It leads to different results. In particular, when the incident angles are different, that is, when the numerical apertures are different, the R, T and A values for the same medium are different.

In order to measure optical characteristics including R, T, and A for a predetermined numerical aperture in consideration of R, T, and A varying depending on the angle of incidence, conventionally, Donis G. Flagello and Tom Milster Was proposed in 1992 by SPIE 1625, pages 246-261, "3d modeling of high numerical aperture imaging in the thin films," Donis G. Flagello, Tom Milster and In 1996, "Theory of high-NA imaging in homogeneous thin films" was proposed by Alan E. Rosenbluth in Journal of Optical Society of America A13, pages 53-64.

This proposed modeling and theory presents a format for obtaining an imaging field formed by a high number of lenses inside a thin film stacked medium, wherein focused light is processed by superposition of plane waves propagated from a solid angle defined by an aperture. This modeling is based on the Debye integral representation and is intended to infer the electric, magnetic and pointing vectors within a thin film multilayered medium, taking into account the vector properties of the polarization and the respective spectral settings of the incident wave. The optical properties of the media obtained by the modeling are represented by pointing vectors.

In the case of measuring R, A, and T for a thin film laminated medium by the conventional optical property measuring method as described above, the optical property value measured for the light focused by a lens having a numerical aperture of 1.0 or more, for example, SIL and SIM There is a problem that the error range is too large to be reliable.

Accordingly, the present invention has been made in view of the above problems, and even when the numerical aperture is set to 1.0 or more, the numerical aperture of the focused light can be designed to accurately measure the optical characteristics of the thin film-laminated media and to design a medium suitable for the numerical aperture setting. It is an object of the present invention to provide a method for measuring optical characteristics of a thin film multilayered medium having a multilayer thin film structure that varies with settings.

The present invention also provides a method for setting the thickness of an optical recording medium for super resolution recording and reproduction so that the thickness of the optical recording medium used in a super resolution optical recording and reproducing apparatus such as a near field recording method can be set correctly according to the numerical aperture of the focused light. Has a different purpose.

, 웨이브 벡터

의 폴라각

, 방위각

대한 함수인 전기장

를 산출하는 단계와; 웨이브 벡터

와 전기장

의 벡터곱을 고체각

에 대해 적분한 형태로 표현되는 자기장

를 산출하는 단계와; 전기장

와 자기장

를 벡터곱하고, 그 값의 실수부를 취한 형태로 표현되는 포인팅벡터

를 산출하는 단계와; 상기 매체의 j번째 층의 반사율(R), 투과율(T) 및 흡수율(A) 각각을 하기의 수학식을 만족하는 형태의 포인팅 벡터로 나타내는 단계;를 포함하는 것을 특징으로 한다..In order to achieve the above object, the optical property measurement method of a thin film laminated medium that changes according to the numerical aperture setting of the focused light is a thin film laminated medium having a multilayer thin film structure that changes according to the numerical aperture setting of the focused light. In the optical property measuring method of a thin film laminated medium for measuring the optical property including reflectance (R), transmittance (T) and absorbance (A) of the j-th layer, the displacement is based on the Debye integral expression.

Wave vector

Polar angle

Azimuth

Electric field as a function of

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field

Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; And representing each of the reflectance (R), transmittance (T) and absorbance (A) of the j-th layer of the medium as a pointing vector satisfying the following equation.

Equation

은 매체의 첫번째 경계에서 포인팅 벡터의 z성분이고,

각각은 상기 매체의 j, v+1번째 경계 각각에서 포인팅 벡터의 z성분이며,

는 적층된 박막에 입사된 총 광량이다.here,

Is the z component of the pointing vector at the first boundary of the medium,

Each is a z component of a pointing vector at each of the j and v + 1 th boundaries of the medium,

Is the total amount of light incident on the laminated thin film.

, 웨이브 벡터

의 폴라각

, 방위각

및 광기록매체의 j번째 층의 두께에 대한 함수인 전기장

를 산출하는 단계와; 웨이브 벡터

와 전기장

의 벡터곱을 고체각

에 대해 적분한 형태로 표현되는 자기장

를 산출하는 단계와; 전기장

와 자기장

를 벡터곱하고, 그 값의 실수부를 취한 형태로 표현되는 포인팅벡터

를 산출하는 단계와; 상기 매체의 j번째 층의 반사율(R), 투과율(T) 및 흡수율(A) 각각을 하기의 수학식을 만족하는 형태의 포인팅 벡터로 나타내는 단계와; 변위

, 웨이브 벡터

의 폴라각

, 방위각

가 결정시, 하기의 수학식을 근거로 소망하는 반사율(R), 투과율(T), 흡수율(A) 각각에 적합한 j번째층의 두께를 설정하는 단계;를 포함하여 광기록/재생장치의 설정된 개구수에 맞는 광기록매체의 j번째 층의 반사율(R), 투과율(T) 및 흡수율(A)을 갖도록 j번째 층의 두께를 설정할 수 있도록 된 것을 특징으로 한다.Further, in order to achieve the above object, the present invention provides a displacement of light focused by an optical recording / reproducing apparatus based on a Debye integral expression.

Wave vector

Polar angle

Azimuth

And the electric field as a function of the thickness of the j th layer of the optical record carrier

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field

Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; Representing each of the reflectance (R), transmittance (T), and absorbance (A) of the jth layer of the medium as a pointing vector satisfying the following equation; Displacement

Wave vector

Polar angle

Azimuth

Setting a thickness of the jth layer suitable for each of the desired reflectance (R), transmittance (T), and absorbance (A), based on the following equation. The thickness of the j-th layer can be set so as to have the reflectance R, the transmittance T, and the absorbance A of the j-th layer of the optical recording medium suitable for the numerical aperture.

Equation

은 매체의 첫번째 경계에서 포인팅 벡터의 z성분이고,

각각은 상기 매체의 j, v+1번째 경계 각각에서 포인팅 벡터의 z성분이며,

는 적층된 박막에 입사된 총 광량이다.here,

Is the z component of the pointing vector at the first boundary of the medium,

Each is a z component of a pointing vector at each of the j and v + 1 th boundaries of the medium,

Is the total amount of light incident on the laminated thin film.

Hereinafter, an optical characteristic measuring method and a thickness setting method of an optical recording medium varying according to the numerical aperture setting of the focused light according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings and equations. .

를 산출하는 단계(S10)와, 자기장

를 산출하는 단계(S20)와, 포인팅 벡터

를 산출하는 단계(S30) 및, 상기 박막 적층형 매체의 소정 층의 반사율(R), 투과율(T) 및 흡수율(A) 각각을 포인팅벡터로 나타내는 단계(S40)로 진행된다.Referring to FIG. 1, the optical property measuring method of the thin film-laminated media that changes according to the numerical aperture setting of the focused light according to the embodiment of the present invention may include an electric field.

Calculating (S10) and the magnetic field

Calculating (S20) and a pointing vector

Is calculated (S30) and each of the reflectance (R), transmittance (T) and absorbance (A) of the predetermined layer of the thin film-laminated medium is represented by a pointing vector (S40).

는 Debye 적분표현에 근거하여 변위

, 웨이브 벡터

의 폴라각

, 방위각

대한 함수로 표현되며, 자기장

는 웨이브 벡터

와 전기장

의 벡터곱을 고체각

에 대해 적분한 형태로 표현된다. 그리고, 상기 포인팅벡터

는 전기장

와 자기장

를 벡터곱하고, 그 값의 실수부를 취한 형태로 표현된다. 상기한 바와 같은 단계들을 구체적으로 살펴보면 다음과 같다.Electric field

Displacement Based on Debye Integral Expression

Wave vector

Polar angle

Azimuth

Expressed as a function of

Wave vector

And electric field

Vector angle of solid angle

Is expressed in an integral form for. And, the pointing vector

Electric field

And magnetic field

Is multiplied by and multiplied by the real part of the value. Looking at the steps as described above in detail.

FIG. 2 is a view schematically showing an optical arrangement of an optical system capable of focusing light on a thin film-laminated medium.

는 수학식 1에 나타낸 바와 같이, 조리개(미도시)에 의해 제한된 고체각(solid)에 대한 평면파의 적분으로 표현될 수 있다.According to the diffraction theory of Fig. 2 and Debye, the electric field of a monochromatic wave focused by the lens 1 in free space

As shown in Equation 1, may be expressed as the integration of the plane wave for the solid angle (limited) by the aperture (not shown).

는 수학식 2이다.Where electric field

Is equation (2).

와 고체각에서 필드의 진폭은 대략 일정하다. 그리고, 수학식 2에서

는 원점에서 시작하여

의 각을 갖는 평면파의 편광 벡터이고,

는 입사매질에서의 웨이브 벡터(wave vector)이다. Here, the monochromatic plane wave is incident from the lens 1 side, and the electric field magnitude

At and the solid angle the field amplitude is approximately constant. And, in Equation 2

Starting at the origin

Is a polarization vector of plane waves with an angle of,

Is the wave vector in the incident medium.

는 s파와 p파로 구분할 수 있으며, 이를 다시 데카르트(cartesian) 성분들로 나눌 수 있다. 초기 편광방향이 x축에 평행하다고 가정할 때,

의 성분들은 하기의 수학식 3과 같이 나타낼 수 있다.remind

Can be divided into s and p waves, which can be further divided into Cartesian components. Assuming that the initial polarization direction is parallel to the x-axis,

The components of may be represented as in Equation 3 below.

은 수학식 4와 같이 방향 코사인으로 나타낼 수 있다.Also,

May be represented by a direction cosine, as shown in Equation 4.

각각은 수학식 5와 같다.here,

Each is as shown in equation (5).

는 웨이브 넘버(wave number)이고,

는 입사 매질의 굴절률이다.

의 원점은 렌즈에 의해 형성된 기하학적인 초점위치이며,

은 상기 초점위치에서 본 다른 임의의 위치, 특히 박막 적층형 매체 내의 임의의 위치를 나타낸다. 각

와 각

각각은

의 폴라(polar)각과 방위(azimuth)각이다. 여기서, 각

와 각

각각은 수학식 6의 범위로 한정된다.In Equation 5

Is the wave number,

Is the refractive index of the incident medium.

The origin of is the geometric focal position formed by the lens,

Denotes any other position seen from the focal position, in particular any position within the thin film laminated media. bracket

And each

Each one

Are the polar and azimuth angles. Where

And each

Each is limited to the range of equation (6).

개의 층으로 이루어진 박막적층형 매체가 위치된 경우, 포커스 필드는 적층된 각 층에서의 다중 반사에 의하여 바뀌게 된다. 적층된 박막에 의해 다중 반사되므로 프레넬(Fresnel) 계수의 항수가 복잡하게 표현된다.As shown in Figure 3, in the image space

When a thin film laminated medium of four layers is located, the focus field is changed by multiple reflections in each stacked layer. Since multiple layers are reflected by the stacked thin films, the terms of the Fresnel coefficients are complicatedly expressed.

의 입사각을 갖는 평면파에 의해 형성된 j번째 층 내에 형성된 전기장을 나타낸 것이다. Equation 7 is

It shows the electric field formed in the j-th layer formed by the plane wave having the incident angle of.

로 정의되며,

는 적층된 필름의 입사면과 기하학적 초점 사이의 거리이다. 또한, 수학식 7에서

와

는 j+1 번째 경계에서 입사되는 웨이브와 출사되는 웨이브 각각을 나타낸 것이다. 그리고,

의 방향 코사인인

스넬의 법칙에 따라 수학식 8 내지 수학식 10과 같은 관계를 가진다.Where z 'is

Is defined as

Is the distance between the plane of incidence and the geometric focus of the laminated film. In addition, in equation (7)

Wow

Denotes each of the incident wave and the exiting wave at the j + 1 th boundary. And,

Direction cosine

According to Snell's law, Equations 8 to 10 have the same relationship.

가 임계각 보다 클때 순수 허수부가 된다. 본 발명은 이와 같은 SIL 렌즈에 대해서도 적용가능하도록 각

를 제공하며, 이 제공된 각

는 복소수가 되도록 일반화되어 있다. When the waves are focused by employing a solid impregnation lens (SIL lens) as the lens 1, the constituent material of the SIL becomes an incident medium having a refractive index of 1.0 or more. Therefore, the left side of the equation (10) is the angle

Is a pure imaginary part when is greater than the critical angle. The present invention is applicable to such a SIL lens.

And provide each

Is generalized to be a complex number.

와

는 수학식 11 및 12에 나타낸 바와 같이, 일반적으로 s파와 p파로 나누어 표현할 수 있다.Expressed in Equation 7

Wow

As shown in equations (11) and (12), in general, the expression can be expressed by dividing the s wave and the p wave.

In addition, in the s wave, the transmission coefficients and the reflection coefficients may be represented by Equations 13 and 14, respectively.

각각은 j+1번째 경계에서 입사된 전기장, 반사된 전기장 및 투과된 전기장의 x방향 성분을 나타낸 것이다. 여기서,

를 포함한 항은 박막 적층형에서는 변하지 않으므로 무시하였다. 처음과 j+1번째 경계에서 프레넬 계수의 비(ratio)로부터, 수학식 15 및 16에 나타낸 바와 같이, j+1 번째 경계에서 입사된 x성분의 전기장 및 반사된 전기장을 얻을 수 있다. Here, the j th layer of the medium is considered as the incident medium. And,

Each represents the x-direction component of the incident electric field, the reflected electric field and the transmitted electric field at the j + 1 th boundary. here,

The terms including are not changed because they do not change in the thin film stack. From the ratio of Fresnel coefficients at the first and j + 1 th boundaries, as shown in equations (15) and (16), the electric and reflected electric fields of the x component incident at the j + 1 th boundary can be obtained.

The electric field of the y component has the same form as that of the x component.

In the p-wave, the direction changes as the electric field is transmitted or reflected at the boundary. As a result, the Fresnel coefficient is defined as the relationship between the magnitudes of the fields, and the signals included in the directions of the fields and the S wave are negligible values.

의

에 의하여

의 데카르트 성분을 표현하기 위하여, 수학식 17의 관계를 이용한다.

of

By

In order to express the Cartesian component of, the relationship of equation (17) is used.

Equation 17 is satisfied not only in the absorbing layer but also in one dielectric layer when the relaxation time is less than the oscillation period of the field.

Using this relationship, the electric field for the p wave has the relationship of the following equations (18) and (19).

Equations 18 and 19 may be expressed as Equations 20 and 21 at the first boundary of the (j + 1) th.

Here, since both the x component and the y component are in the tangential direction, the y component has the same form as the equations (20) and (21).

Unlike the s wave, the z direction field in the p wave is given by Equations 22 and 23.

Similarly, each of Equations 22 and 23 may be expressed as Equations 24 and 25 at the (j + 1) th first boundary.

Subsequently, Equations 14, 19, and 23 are substituted into Equation 11, and Equations 15, 20, and 24 are substituted into Equation 12, and the electric field in the jth layer may be represented by the following Equations 26 and 27.

는 수학식 28로 표현된다.here,

Is expressed by equation (28).

은 앞서 설명한 바와 같이, 수학식 26과 같은 형태를 가진다.And,

As described above, has a form as shown in Equation 26.

In Equations 26 and 27, the electric field at the first interface is given by Equations 29 and 30.

The same applies to the y component and the z component. Substituting Equations 28 and 29 into Equation 26, the x component of the total electric field in the jth layer is represented by Equation 31.

Similarly, the y and z components of the total electric field in the j th layer are given by Equations 32 and 33.

층으로 구성된 다층 박막 구조에 있어서, (j+1)번째 경계에서 반사계수 및 투과계수는 수학식 34 내지 37과 같이 주어진다. 여기서, 수학식 34 및 35는 s파에 대한 것이고, 수학식 36 및 37은 p파에 대한 것이다.

In the multilayer thin film structure composed of layers, the reflection coefficient and the transmission coefficient at the (j + 1) th boundary are given by Equations 34 to 37. Here, equations 34 and 35 are for the s wave, and equations 36 and 37 are for the p wave.

In Equations 34 to 37, m _ij is represented by a matrix as in Equation 38.

은 수학식 39와 같이 주어진다.And,

Is given by Equation 39.

과 s파 및 p파에 대한

각각은 수학식 40 내지 42에 나타낸 바와 같다.here,

For s and p waves

Each is as shown in equations (40) to (42).

By substituting Equations 34 to 37 into Equations 31, 32 and 33, a complete representation of the electric fields in the jth layer is possible.

In addition, in the superimposed fields, the reflectance, transmittance, and absorptance can be easily expressed as pointing vectors having the same format as that for the plane wave, as shown in Equation 43.

는

의 복소 공액이며,

는 수학식 44와 같이 주어진다.here,

Is

Is a complex conjugate of,

Is given by Equation 44.

의 데카르트 성분들은 앞서 표현된 수학식 31, 32 및 33과 같이 주어진다. 그러므로, 적층 박막의 모든 위치에서 포인팅 벡터를 구할 수 있다.Where, in Equations 43 and 44

The Cartesian components of are given by Equations 31, 32 and 33 expressed above. Therefore, the pointing vector can be obtained at all positions of the laminated thin film.

를 정의하면, j번째 층의 반사율(R), 투과율(T) 및 흡수율(A) 각각은 수학식 45, 46 및 47과 같 이 주어진다.As the z component of the pointing vector at the jth boundary of the multilayer structure

To define the reflectance (R), transmittance (T) and absorbance (A) of the j-th layer is given by the equations (45), (46) and (47).

는 적층된 박막에 입사된 총 광량이다.here,

Is the total amount of light incident on the laminated thin film.

In addition, the absorption energy distribution g (x, y, z) is as shown in Equation 48.

This represents the term representing the heat source in the thermal analysis of the multilayer thin film by the focused light.

Equations as described above are programmed to be computer-analyzed and used to measure the optical properties, i.e., R, T, and A of a medium having a multilayer thin film structure that changes with the setting of the numerical aperture NA.

In addition, the optical characteristic measurement method of the thin film-laminated media according to the present invention can be implemented as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, optical data storage device, and the like. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

층(13), 100nm의 두께를 가지며 흡수층인

층(15), 50nm의 두께를 갖는

층(17)으로 구성되어 있다. 여기서, 입사광(L)은 상기

층(17)쪽에서 입사된다.3 shows a medium having a three-layer thin film stack structure. The thin film laminated medium 10 has a substrate 11 and a thickness of 50 nm in sequence on the substrate 11.

Layer 13, having a thickness of 100 nm,

Layer 15, having a thickness of 50 nm

It consists of layer 17. Here, the incident light L is

Incident on the layer 17 side.

4 is a graph showing the change in energy flow rate according to the change in energy flow rate according to the change in depth from the incidence plane. In the case where the thick solid line is the numerical aperture 0, the dashed line is the numerical aperture 0.6 and the dotted line is the numerical aperture. The case of 0.85 is shown. This represents the magnitude of the pointing vector that changes along the traveling direction of the irradiated light for the numerical apertures 0, 0.6 and 0.85, respectively. Here, the numerical aperture 0 corresponds to a case where light is incident in a direction perpendicular to the incident surface of the medium.

From the graph as shown in FIG. 4 and the calculation according to Equations 45, 56, and 47, the change of R, T, and A according to the change of the numerical aperture can be seen. This is shown in FIG. 5. FIG. 5 illustrates changes in R, T, and A with increasing numerical aperture in the numerical aperture of 0 to 1.0 of the multilayer thin film multilayer media shown in FIG. 3.

Referring to FIG. 5, it can be seen that as the numerical aperture increases, the values of R, T, and A deviate from the case where the numerical aperture is 0, that is, the plane wave. In particular, as the numerical aperture increases from 0 to 1.0, the reflectance R increases from 0.268 to 0.312.

As a result, as shown in FIG. 6, the reflectance changes as the incident angle changes. FIG. 6 is a graph illustrating reflectance change according to incident angles of s and p waves of the multilayer thin film multilayer media illustrated in FIG. 3.

층(17)의 두께에 따른 반사율 변화를 나타낸 것으로, 굵은 실선은 개구수 0인 경우, 대시(-) 선은 개구수 0.6인 경우 그리고, 점선은 개구수 0.85의 경우를 나타낸 것이다. 여기서, 개구수 0.6 및 0.85에 대한 반사율 주기는 상부

층(17)의 두께가 두꺼워질수록 길어짐을 알 수 있다. 즉, 층의 두께가 증가할 수록 반사율의 편차가 증가함을 알 수 있다.FIG. 7 is a top view of the multilayer thin film stacked media shown in FIG.

The change in reflectance according to the thickness of the layer 17 is shown, where the thick solid line represents the numerical aperture 0, the dashed line represents the numerical aperture 0.6, and the dotted line represents the numerical aperture 0.85. Here, the reflectance periods for the numerical apertures 0.6 and 0.85 are

It can be seen that the thicker the layer 17 is, the longer it becomes. That is, it can be seen that the variation in reflectance increases as the thickness of the layer increases.

FIG. 8 is a schematic view of a solid immersion lens (SIL) 5 and a thin film stacked medium 10. The structure of the thin film stacked medium is the same as that of FIG. 3, and the refractive index of the SIL is 1.9.

FIG. 9 is a graph showing changes in R, T, and A with increasing numerical aperture in the numerical aperture of 0 to 1.5 in FIG. 8. FIG. 10 is a graph illustrating changes in reflectances of s and p waves according to changes in incident angles of plane waves incident on the thin film stack including the incident medium, the air gap, and the thin film stack 10 of FIG. 3. Here, the refractive index of the incident medium is the same as that of the solid-impregnated lens 5 of FIG. 8, and the air gap is set to 100 nm.

In this case, looking at Figure 9, it can be seen that the R, T and A curve bump around the numerical aperture 1.14. In particular, referring to FIG. 10, it can be seen that the reflectance of the p-wave is largely oscillated around the incident angle of 34 degrees.

The field focused by the SIL 5 is composed of a far field and an evanescent field, and the infinite field corresponds to a light ray whose incident angle is larger than the critical angle. Unlike the vibration of the far field, the infinite field decreases exponentially in proportion to the width of the air gap, which is indispensable for each spectrum of the incident field in calculating the optical properties of the medium having the thin film layered structure.

층(15)에서 개구수 0.6, 0.85 및 1.2 각각에 대하여 빔의 중심으로부터의 거리 변화에 따른 에너지 유동율 변화를 나타낸 그래프이다.11 is of FIG. 3

It is a graph showing the change in energy flow rate with the change in distance from the center of the beam for the numerical apertures 0.6, 0.85 and 1.2 in the layer 15, respectively.

Looking at the curve corresponding to the numerical aperture 1.2, it has a larger side lobe than the other numerical aperture. Therefore, it is expected from these results that the accuracy of thermal analysis can be enhanced, especially with SIL.

As described above, in the case of using the optical property measuring method for the thin film laminated medium according to the present invention, the reflectance, transmittance, and absorptance of the thin film laminated medium varying according to the numerical aperture of the focused light can be calculated. There is an advantage that the design of the medium is easy.

Hereinafter, with reference to the accompanying drawings, a method of setting the thickness of the optical recording medium to match the numerical aperture setting of the focused light will be described in detail.

를 산출하는 단계와, 자기장

를 산출하는 단계와, 포인팅 벡터

를 산출하는 단계 및, 상기 광기록매체의 j번째 층의 반사율(R), 투과율(T) 및 흡수율(A) 각각을 포인팅벡터로 나타내는 단계 및, 소망하는 R, T, A 값을 만족하도록 전기장

를 결정하는 변수인 광기록매체의 두께를 설정하는 순서로 진행된다.The method of setting the numerical aperture of the optical recording / reproducing apparatus according to the embodiment of the present invention is particularly suitable for the optical system having an approximate numerical aperture of 1.2, the standard of the near field recording optical apparatus.

Calculating the magnetic field

Calculating a and pointing vector

Calculating each of the reflectances (R), transmittances (T), and absorbances (A) of the jth layer of the optical recording medium as a pointing vector;

It proceeds in the order of setting the thickness of the optical recording medium which is a variable for determining.

는 Debye 적분표현에 근거하여 변위

, 웨이브 벡터

의 폴라각

, 방위각

, 광기록매체의 j번째 층의 두께 대한 함수로 표현되며, 자기장

는 웨이브 벡터

와 전기장

의 벡터곱을 고체각

에 대해 적분한 형태로 표현된다. 그리고, 상기 포인팅벡터

는 전기장

와 자기장

를 벡터곱하고, 그 값의 실수부를 취한 형태로 표현된다. 상기한 바와 같은 R, T, A의 표현은 앞서 설명된 수학식 1 내지 수학식 47을 통하여 가능하므로, 그 자세한 설명은 생략한다. Electric field

Displacement Based on Debye Integral Expression

Wave vector

Polar angle

Azimuth

, Expressed as a function of the thickness of the jth layer of the optical recording medium,

Wave vector

And electric field

Vector angle of solid angle

Is expressed in an integral form for. And, the pointing vector

Electric field

And magnetic field

Is multiplied by and multiplied by the real part of the value. Since the expression of R, T, A as described above is possible through the above-described Equations 1 to 47, detailed description thereof will be omitted.

Further, the thickness setting method of the optical recording medium suitable for the optical recording / reproducing apparatus for the super resolution recording according to the present invention can be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, optical data storage device, and the like. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

12 is a view showing an example of an optical recording medium for explaining the thickness setting of the optical recording medium according to the present invention.

등의 재질로 구성되며, 상기 기록막(23)은

으로 입사광을 상당부분 흡수한다. 상기 반사막(25)은 상기 기록막(23)에 입사되는 광을 기판(21)쪽으로 반사시키기 위한 층으로, 알루미늄등의 재질로 구성된다.Referring to the drawings, the optical recording medium shows a phase change type optical recording medium in which four layers are stacked on a substrate. The film 23, the second dielectric layer 24, and the reflective film 25 are provided. The substrate 21 is made of a transparent material such as polycarbonate as shown. The first and second dielectric layers 22 and 24 transmit most of incident light.

It is made of a material such as, the recording film 23 is

This absorbs a substantial portion of incident light. The reflective film 25 is a layer for reflecting light incident on the recording film 23 toward the substrate 21, and is made of a material such as aluminum.

R)의 변화 및, 니어필드 기록용 광학장치에 적용시 에어갭의 변동에 따른 반사율 및 흡수율 특성을 살펴보면 다음과 같다.As described above, when the optical recording medium is constructed, the reflectance difference which is the difference between the reflectance according to the numerical aperture change, the light absorption ratio between crystalline and amorphous, the crystalline reflectance Rc and the amorphous reflectance Ra,

The reflectance and absorptance characteristics according to the change of R) and the air gap variation when applied to the near field recording optical device are as follows.

FIG. 13 is a graph illustrating a change in reflectance between s-wave and p-wave according to the change of the incident angle in the optical recording medium shown in FIG. 12. 15 is a graph showing a change in reflectance according to a change in the numerical aperture of incident light in the optical recording medium shown in FIG. 12.

Referring to the drawings, it can be seen that in the case of the optical recording medium having the configuration shown in FIG. 12, the reflectance gradually decreases as the numerical aperture becomes 0.8, 1.0, or the like.

FIG. 15 is a graph illustrating a change in reflectance according to a change in thickness of a first dielectric layer positioned on a side where light is incident on the optical recording medium illustrated in FIG. 12, where a solid line represents a plane wave, and a thick dotted line represents a numerical aperture of 0.6, The thin dotted line shows the case where the numerical aperture is 0.85 and the one-dot chain line is the numerical aperture 1.2. When the thickness of the first dielectric layer is changed in the drawings, the reflectance curve for an optical system having a numerical aperture of 0.6 and a numerical aperture of 0.85 is similar to that of a plane wave. Therefore, the optical recording medium suitable for the numerical aperture 0.6 and the numerical aperture 0.85 can be designed by determining the thickness of the first dielectric layer considering only plane waves.

On the other hand, looking at the near-field recording optical system having a numerical aperture of 1.2, the reflectance change curve according to the change in the thickness of the first dielectric layer appears different from the reflectance curve of the plane wave.

R)의 변화를 나타낸 그래프로, 실선은 평면파의 경우를 나타낸 것이고, 굵은 점선은 개구수 0.6, 가는 점선은 개구수 0.85, 일점쇄선은 개구수 1.2인 경우를 나타낸 것이다. 그리고, 도 17은 도 12에 도시된 광기록매체에서 제1유전체층의 두께 변화에 따른 비정질 흡수율에 대한 결정질 흡수율 비(Ac/Aa)의 변화를 나타낸 그래프로, 실선은 평면파의 경우를 나타낸 것이고, 굵은 점선은 개구수 0.6, 가는 점선은 개구수 0.85, 일점쇄선은 개구수 1.2인 경우를 나타낸 것이다. 즉, 도 16 및 도 17을 살펴볼 때, 개구수 1.2인 경우는 평면파와는 다른게

R과 비정질 흡수율에 대한 결정질 흡수율 비(Ac/Aa)가 변화함을 알 수 있다. FIG. 16 illustrates a difference in reflectance which is a difference between crystalline reflectivity Rc and amorphous reflectance Ra according to a change in thickness of the first dielectric layer in the optical recording medium shown in FIG.

In the graph showing the change in R), the solid line represents the case of plane wave, the thick dotted line represents the numerical aperture 0.6, the thin dotted line represents the numerical aperture 0.85, and the dashed dotted line represents the numerical aperture 1.2. FIG. 17 is a graph illustrating a change in the crystalline absorption ratio (Ac / Aa) with respect to the amorphous absorption rate according to the thickness change of the first dielectric layer in the optical recording medium shown in FIG. 12, wherein a solid line represents a plane wave case. The thick dotted line shows a case of numerical aperture 0.6, the thin dotted line of 0.85 numerical aperture, and the dashed dotted line of numerical aperture 1.2. 16 and 17, the numerical aperture 1.2 is different from the plane wave.

It can be seen that the ratio of crystalline absorption rate (Ac / Aa) to R and amorphous absorption rate changes.

R 값, 및 Ac/Aa 값을 얻을 수 있다.Therefore, when determining the reflectance of the optical recording medium using plane waves as in the conventional method, there may be a significant difference from the desired reflectance. In this case, according to the optical recording medium thickness setting method of the present invention, when the thickness of the first dielectric layer of the optical recording medium is determined by using the results of the above-described equations (45) to (47), the near numerical aperture is 1.2. Desired reflectivity for field optics,

R value and Ac / Aa value can be obtained.

R 값, 및 Ac/Aa 값은 에어갭에 따라 변화한다. 이와 같은 에어갭 설정에 따른 반사율,

R 값, 및 Ac/Aa 값 각각을 도 20 내지 도 22에 나타내었다.On the other hand, as described above, even when the thickness of the optical recording medium is determined to be suitable for the near field optical apparatus, the reflectance of the optical recording medium,

The R value and Ac / Aa value change with the air gap. Reflectance according to the air gap setting,

R values and Ac / Aa values are respectively shown in FIGS. 20 to 22.

R)의 변화를 나타낸 그래프이며, 도 22는 도 11에 도시된 광기록매체에서 에어갭 변화에 따른 비정질 흡수율에 대한 결정질 흡수율 비(Ac/Aa)의 변화를 나타낸 그래프이다.FIG. 20 is a graph illustrating a change in reflectance according to an air gap change in the optical recording medium shown in FIG. 11, and FIG. 21 is a graph showing crystalline reflectivity Rc and amorphous reflectance according to an air gap change in the optical recording medium shown in FIG. 11. Reflectance difference (the difference between Ra)

FIG. 22 is a graph showing the change of R), and FIG. 22 is a graph showing the change of the crystalline absorption ratio (Ac / Aa) to the amorphous absorption rate according to the air gap change in the optical recording medium shown in FIG.

R 값, Ac/Aa 값을 얻을 수 있다.Therefore, when the layer thickness of the optical recording medium having the layer structure as shown in Fig. 11 is set to be suitable for the near field optical device having a numerical aperture of about 1.2, the light obtained based on the above equations 45 to 47 By utilizing the layer thickness of the recording medium, in particular the thickness of the first dielectric layer, and the R, T, A characteristics according to the air gap change of the optical device, the desired R,

R value and Ac / Aa value can be obtained.

Therefore, in the case of measuring the optical properties of the thin film laminated media having the multilayer thin film structure as described above, even if the numerical aperture is set to 1.0 or more, the optical properties of the thin film laminated media can be accurately measured to design a medium suitable for the numerical aperture setting. have. Further, by providing a recording medium on which a program for measuring the optical characteristics of the thin film laminated medium is recorded, a thin film laminated medium suitable for this can be set even when the numerical aperture is set to 1.0 or more by executing the above program using a computer.

Further, through the optical recording medium thickness setting method according to the present invention, the multilayer film thickness that matches the reflectance, transmittance, and absorptivity characteristics of the multilayer reflective film with respect to the high numerical aperture can be calculated. The thickness of the optical recording medium used in the playback apparatus can be set correctly. Further, by providing a recording medium on which a program for setting the thickness of the optical recording medium is recorded, by executing the program using a computer, even when the numerical aperture is set to 1.0 or more, a thin film laminated medium suitable for this can be set.

Claims (8)

Optical properties of thin film laminated media for measuring optical properties including reflectance (R), transmittance (T) and absorbance (A) of j-th layer of thin film multilayer media having a multilayer thin film structure that changes with numerical aperture of focused light In the measuring method, Displacement Based on Debye Integral Expression

Wave vector

Polar angle

Azimuth

, the electric field as a function of the thickness of the jth layer

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field

Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; Representing the reflectance (R), transmittance (T), and absorbance (A) of the j-th layer of the medium as a pointing vector having a form satisfying the following equation; Method for measuring the optical properties of a thin film laminated media that varies with time. Equation

here,

Is the z component of the pointing vector at the first boundary of the medium,

Each is a z component of a pointing vector at each of the j and v + 1 th boundaries of the medium,

Is the total amount of light incident on the laminated thin film. The electric field size of claim 1.

When the amplitude of the field at and the solid angle is approximately constant, the electric field

Is, Method for measuring the optical properties of a thin film laminated media that changes according to the numerical aperture setting of the focused light, characterized in that the following equations are satisfied. Equation

Equation

here,

Starting at the origin

Is a polarization vector of plane waves with an angle of,

Is the wave vector in the incident medium. The method of claim 1, wherein the pointing vector

And magnetic field

A method for measuring optical characteristics of a thin film-laminated medium, each of which varies according to the numerical aperture setting of the focused light, wherein each of the following equations is satisfied. Equation

Equation

here,

Is

Is a complex conjugate. With computer Displacement Based on Debye Integral Expression

Wave vector

Polar angle

Azimuth

electric field as a function of thickness of layer j

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field

Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; Representing each of the reflectance (R), transmittance (T), and absorbance (A) of the jth layer of the medium as a pointing vector satisfying the following equation; A computer-readable recording medium having recorded thereon a program for measuring optical properties including reflectance (R), transmittance (T), and absorbance (A) of the jth layer of a thin film multilayer medium having a multilayer thin film structure. Equation

here,

Is the z component of the pointing vector at the first boundary of the medium,

Each is a z component of a pointing vector at each of the j and v + 1 th boundaries of the medium,

Is the total amount of light incident on the laminated thin film. In the optical recording medium having a multilayer thin film structure suitable for the set numerical aperture of the optical recording / reproducing apparatus, the light for setting the layer thickness so that the reflectance (R), transmittance (T) and absorption (A) of the j-th layer have desired values. In the recording medium thickness setting method, Displacement of light focused by the optical recorder / playback device based on the Debye integral expression

Wave vector

Polar angle

Azimuth

And the electric field as a function of the thickness of the j th layer of the optical record carrier

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field

Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; Representing each of the reflectance (R), transmittance (T), and absorbance (A) of the jth layer of the optical recording medium as a pointing vector satisfying the following equation; Displacement

Wave vector

Polar angle

Azimuth

In this determination, calculating the thickness of the j-th layer suitable for each of the desired reflectance (R), transmittance (T), and absorbance (A) on the basis of the following equation; A method of setting the thickness of an optical recording medium that varies with the number setting. Equation

here,

Is the z component of the pointing vector at the first boundary of the medium,

Each is a z component of a pointing vector at each of the j and v + 1 th boundaries of the medium,

Is the total amount of light incident on the laminated thin film. 6. The electric field size of claim 5

When the amplitude of the field at and the solid angle is approximately constant, the electric field

Is, The thickness setting method of the optical recording medium, characterized in that to satisfy the following equation. Equation

Equation

here,

Starting at the origin

Is a polarization vector of plane waves with an angle of,

Is the wave vector in the incident medium. The method of claim 5, wherein the pointing vector

And magnetic field

And each of which satisfies the following equations. Equation

Equation

here,

Is

Is a complex conjugate. With computer Displacement of light focused by the optical recorder / playback device based on the Debye integral expression

Wave vector

Polar angle

Azimuth

And the electric field as a function of the thickness of the j th layer of the optical record carrier

Calculating a; Wave vector

And electric field

Vector angle of solid angle

Magnetic field expressed in integral form for

Calculating a; Electric field

And magnetic field

Is a vector multiplied by and the pointing vector represented by the real part of the value.

Calculating a; Representing each of the reflectance (R), transmittance (T), and absorbance (A) of the jth layer of the medium as a pointing vector satisfying the following equation; Displacement

Wave vector

Polar angle

Azimuth

Setting the thickness of the j-th layer suitable for each of the desired reflectance (R), transmittance (T), and absorbance (A) based on the following equation; A computer-readable recording medium having recorded thereon a program for setting the thickness of the j-th layer to have a reflectance (R), a transmittance (T), and an absorption (A) of the j-th layer of the optical recording medium matching the numerical aperture. Equation

here,

Is the z component of the pointing vector at the first boundary of the medium,

Each is a z component of a pointing vector at each of the j and v + 1 th boundaries of the medium,

Is the total amount of light incident on the laminated thin film.

Images