KR101711376B1 - Digital 3D lithography method and apparatus - Google Patents

Abstract

The present invention is a digital three-dimensional lithography method capable of precisely forming various types of three-dimensional exposure dose distributions using the conventional two-dimensional digital exposure apparatus as it is without the need to adjust the position of the exposure elements in the vertical direction or alignment with stacking, A digital three-dimensional lithography method capable of forming a three-dimensional exposure dose distribution by digital two-dimensional lithography by virtual layering is provided. The digital three-dimensional lithography method of the present invention includes the steps of: determining a target exposure amount distribution based on characteristics of a photoresist formed on a substrate and a shape of a three-dimensional structure to be fabricated in a control unit; (N is a natural number equal to or greater than 1) layers on the basis of the corrected target exposure amount distribution, and dividing the n divided exposure dose distributions A step of forming a digital mask by controlling the optical modulator according to the pattern set in each of the scan steps, and a step of exposing the photoresist film based on the digital mask .

Description

[0001] Digital 3D lithography method and apparatus [0002]

The present invention relates to a method of forming a target exposure dose distribution determined by a characteristic of a photoresist film and a shape of a three-dimensional structure on a substrate on which a photoresist film is formed to form a three-dimensional structure, and a method of offset- To a digital three-dimensional lithography method capable of forming a three-dimensional target exposure dose distribution by digital two-dimensional lithography by virtual layering.

Conventional techniques for manufacturing a three-dimensional structure by photo-lithography include a method using a gray scale mask, a method of direct imaging or writing, a reflow of a photosensitive material, , A stereo lithography method in which a layer is cured and a three-dimensional layer is formed, and the like. However, the gray scale method is time-consuming and costly to manufacture masks and masters, and the reflow method is difficult to fabricate structures requiring precision. In addition, the direct imaging or writing method and the stereolithography method have considerable time and cost in direct processing, resulting in a discrete phenomenon between the layers resulting in a reduction in surface roughness. And, most of the prior art is a lamination method consisting of repetition of two-dimensional lithography, alignment along the lamination is essential and very important.

Conventional techniques for fabricating three-dimensional structures by photolithography are based on lithography using two-dimensional lithography as a basis, direct imaging lithography using a laser as a direct pattern, and stereolithography using a spatial light modulator, a three-dimensional structure can be patterned by repeating the two-dimensional lithography in a stacking manner in which the vertical positions of the exposure elements (optical system, substrate, or mask) Accordingly, alignment along the stacking is essential and important. Furthermore, in the case where the three-dimensional structure is a square having a complicated embossing or embossing shape, a part of an ellipsoid, a cone shape, and a pyramid shape, a square, a rectangular or a honeycomb arrangement, it is difficult to adjust the position of the exposure element in the vertical direction, The three-dimensional exposure amount profile formed as a result of exposure is not precise. In addition, since the exposure process is uneconomical and inefficient due to the time and cost required for position adjustment and alignment, it is difficult to apply the lithography to mass production of actual three-dimensional structures.

The present invention is a digital three-dimensional lithography method capable of precisely forming various types of three-dimensional exposure dose distribution using the existing two-dimensional digital exposure apparatus as it is without the need to adjust the position of the exposure elements in the vertical direction or align them according to stacking Dimensional digital lithography method capable of forming a three-dimensional exposure dose distribution by digital two-dimensional lithography by virtual layering.

A digital three-dimensional lithography method according to an embodiment of the present invention

Determining a target exposure dose distribution based on the characteristics of the photoresist formed on the substrate and the shape of the three-dimensional structure to be fabricated;

The control unit offset-corrects the target exposure dose distribution to determine a corrected target exposure dose distribution;

Forming divided exposure amount distributions divided into n (n is a natural number of 1 or more) layers based on the corrected target exposure amount distribution;

Selecting one of the n divided exposure dose distributions in each scan step and setting the selected pattern as a pattern to be exposed;

Controlling a light modulator according to the pattern set in each scan step to form a digital mask; And

And exposing the photoresist film based on the digital mask.

The step of determining the corrected target exposure dose distribution

Determining, by the control unit, divided exposure amount distributions divided into n (n is a natural number of 1 or more) layers based on the target exposure amount distribution;

Summing the divided exposure dose distributions to determine an accumulated exposure dose distribution; And

Determining an offset amount based on a difference between the target exposure amount distribution and the cumulative exposure amount distribution, and offset-correcting the target exposure amount distribution by the offset amount.

The offset correcting step may perform offset correction to reduce the first exposure amount distribution of the first layer by the first offset amount and offset correction to increase the nth exposure amount distribution of the nth layer by the nth offset amount.

The offset correction step may perform offset correction on the Lth layer (L is a natural number smaller than 1 and a natural number smaller than n) by the Lth offset amount with respect to the divided exposure amount distribution.

The n divided exposure amount distributions may be formed into n two-dimensional horizontal sections obtained by evenly dividing the target exposure amount distribution into n layers and selecting one horizontal section belonging to each layer with respect to the divided n layers have.

Wherein the pattern to be exposed in each of the scan steps is grouped into n groups of all the scan steps and one of the n divided exposure dose distributions is grouped into n groups of scan steps and n divided exposure dose distributions, Can be selected and set.

A digital three-dimensional lithography apparatus according to another embodiment of the present invention

A light source;

An optical modulator that includes a plurality of digital micromirror elements and reflects the light incident from the light source part and irradiates the light to the photoresist film on the substrate; And

And a controller for determining a corrected target exposure amount distribution based on the target exposure amount distribution, the divided exposure amount distribution, and the cumulative exposure amount distribution, and controlling the optical modulator according to the corrected target exposure amount distribution.

The control unit may determine an offset amount based on the difference between the target exposure amount distribution and the cumulative exposure amount distribution, and may offset the target exposure amount distribution by the offset amount to determine the corrected target exposure amount distribution.

The present invention eliminates the need for adjusting the position of the exposure elements in the vertical direction or aligning process according to the stacking by virtue of the virtual layering, and it is possible to perform the lithography process more accurately than the conventional lithography method, and the time and cost required for the alignment can be reduced . In addition, exposure can be performed in accordance with the corrected target exposure amount distribution to obtain a precise three-dimensional structure.

FIGS. 1A to 1D schematically illustrate a process of patterning a three-dimensional structure by a digital three-dimensional lithography method according to an embodiment of the present invention.
FIG. 2A is a view showing the target exposure amount distribution E (x, y) divided into four layers shown in FIG. 1B by rotating 90 degrees counterclockwise. FIG. 2B shows the horizontal cross-section of each layer of the target exposure dose distribution shown in FIG. 2A arranged side by side.
FIG. 3 shows steps in which a target exposure dose distribution is obtained by accumulation of a divided exposure dose distribution divided into equal-interval layers according to an embodiment of the present invention.
4A shows a cross-sectional view of the amount of exposure exposed in accordance with an embodiment of the present invention. FIG. 4B shows the exposure amount shown in FIG. 4A by dividing the exposure amount into four layers.
5A to 5F show a process in which the divided exposure dose distribution of each layer is determined by an exposure process of each scan step.
Fig. 6 shows the distribution of the exposure dose I (exposure energy) obtained by accumulating the respective exposure amounts in the exposure steps of the respective scan steps in Figs. 5A to 5F.
FIG. 7 shows the cumulative divided exposure dose distribution, cumulative exposure dose distribution Y (x), target exposure amount distribution E (x), and corrected exposure amount distribution E '(x) of each layer.
8 shows the cumulative exposure amount distribution (Y (x)), the target exposure amount distribution (E (x)) and the corrected exposure amount distribution (E '(x)) of the Lth layer.
9 is a schematic diagram of a digital three-dimensional lithography apparatus according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size and thickness of each element may be exaggerated for clarity of explanation.

FIGS. 1A to 1D schematically illustrate a process of patterning a three-dimensional structure by a digital three-dimensional lithography method according to an embodiment of the present invention.

Fig. 1A shows a cross-sectional view of a shape (f (x, y)) of a three-dimensional structure to be processed. The shape of the three-dimensional structure (f (x, y)) may be a three-dimensional CAD data such as an IGS, STL or STEP format or a primitive defined for a relatively simple shape such as a rectangle, a cone, a pyramid and a retro reflector . ≪ / RTI >

1B is a cross-sectional view of a three-dimensional target exposure amount distribution E (x, y). In order to expose a photoresist film formed on a substrate by photolithography to form a three-dimensional structure, a three-dimensional exposure dose distribution matching the characteristics of the photoresist film must be formed. Therefore, the target exposure dose distribution E (x, y) can be determined based on the characteristics of the photosensitive film and the shape f (x, y) of the three-dimensional structure in the control unit of the exposure apparatus. The target exposure dose distribution E (x, y) can be calculated by the following equation (1), which is a correlation equation of the thickness of the photosensitive film to be processed with respect to the exposure energy, which approximates the thickness of the photosensitive film to be processed with the logarithm of exposure energy (exposure dose).

The photoresist contrast? Of the photoresist film in Equation (1) satisfies the following equation (2).

는 감광막의 최대 가공 두께이다. 그리고,

은 최소 노광량을 의미하고,

는 최대 노광량을 의미한다. 가공 두께 t(x, y)는 다음 수학식 3을 만족시킨다.Here, t (x, y) is the working thickness of the photosensitive film,

Is the maximum processing thickness of the photosensitive film. And,

Quot; means the minimum exposure amount,

Means the maximum exposure amount. The machining thickness t (x, y) satisfies the following equation (3).

Then, the target exposure dose distribution E (x, y) satisfies the following equation (4).

1C is a sectional view of the divided exposure dose distribution in which the target exposure dose distribution E (x, y) is divided into four layers. Although the target exposure dose distribution E (x, y) is divided into four layers in this embodiment, the target exposure dose distribution E (x, y) is not limited thereto. The divided exposure dose distribution for each of n layers in the control unit of the exposure apparatus can be determined by slicing the target exposure dose distribution E (x, y) into n layers of equal intervals. Further, the n divided exposure dose distributions can be formed of n two-dimensional horizontal sections obtained by selecting one horizontal section belonging to each layer of the target exposure dose distribution E (x, y) divided into n layers.

FIG. 1D shows a cross-sectional view of a three-dimensional structure obtained by exposing the photoresist film 20 on the substrate 10 based on the divided exposure dose distribution of n layers determined above. In the three-dimensional structure of FIG. 1D, since the energy gradient section exists in the divided exposure dose distribution of each layer, the three-dimensional structure formed by the difference between the target exposure amount and the actual exposure amount may differ from the target three-dimensional structure.

FIG. 2A is a view showing the target exposure amount distribution E (x, y) divided into four layers shown in FIG. 1B by rotating 90 degrees counterclockwise. FIG. 2B shows the horizontal cross-section of each layer of the target exposure dose distribution shown in FIG. 2A arranged side by side. When the target exposure dose distribution E (x, y) is divided into n layers, n horizontal cross sections can be considered and n divided exposure dose distributions can be obtained from n horizontal cross sections.

FIG. 3 shows steps in which a target exposure dose distribution is obtained by accumulation of a divided exposure dose distribution divided into equal-interval layers according to an embodiment of the present invention.

Referring to FIG. 3, the spatial light modulator tilted at a certain angle moves by a unit scan distance P, and alternately performs exposure for each layer in order to realize a target exposure dose distribution. Here, the unit scan distance P refers to the distance that the digital micromirror device of the optical modulator moves during one on / off operation. According to the present embodiment, the exposure is performed in the first scan step for the second layer after exposing in the 0th scan step for the first layer of the divided exposure amount distribution. And then exposed in the second scan step for the third layer, and then exposed in the third scan step for the fourth layer. Then, the exposure is performed again in the fourth scan step for the first layer, and the exposure in the scan step for each layer is alternately performed to realize the target exposure amount distribution. In the control unit of the exposure apparatus, the pattern to be exposed in each scan step is grouped into n groups, and the scan steps of n groups correspond to the n divided exposure amounts distributions, one of the n divided exposure amount distributions And can be set by selecting the divided exposure amount distribution. Then, the divided exposure dose distribution selected at each scan step is set as a pattern to be exposed, and then the control unit controls the optical modulator according to the pattern to form a digital mask. And then exposes the photoresist film based on the digital mask. Therefore, according to the present embodiment, since the re-arranging step between layers is not necessary after the exposure for each layer is completed, the time required for re-arrangement can be shortened and the productivity can be improved. It is also possible to prevent degradation of pattern quality due to misalignment between layers. The n divided exposure amount distributions may be formed into n two-dimensional horizontal sections obtained by evenly dividing the target exposure amount distribution into n layers and selecting one horizontal section belonging to each layer with respect to the divided n layers have. The pattern to be exposed in each of the scan steps is grouped into n groups, and one of the n divided exposure dose distributions is selected so that the n divided scan steps and the n divided exposure dose distributions can correspond to each other .

On the other hand, in the conventional three-dimensional lithography method, in the case of sequentially exposing layers one by one by a mask or a mast, the first mask is mounted and aligned on the exposer, and the first layer is exposed. Then, the first mask is replaced with a second mask, mounted and reordered to expose the second layer. Accordingly, the target exposure amount is realized by repeating the mounting, alignment, and exposure processes as many as the number of layers. On the other hand, in the case of direct exposure without using a mask or a mast, the alignment and exposure process is repeated to achieve the target exposure dose. According to the conventional three-dimensional lithography method, since it is necessary to rearrange each layer to each other, it takes a lot of time to rearrange and the alignment is not perfect and the quality of the pattern may be deteriorated.

4A shows a cross-sectional view of the amount of exposure exposed in accordance with an embodiment of the present invention. FIG. 4B shows the exposure amount shown in FIG. 4A by dividing the exposure amount into four layers. The divided exposure dose distribution of each layer shown in FIG. 4B means the total exposure amount of all the exposure amounts in the exposure process performed in the scan steps corresponding to each layer in FIG. That is, the divided exposure dose distribution of the first layer is the total of the exposure amounts in the 0th, 4th, 8th and 12th scan steps corresponding to the exposure process for the first layer, and the divided exposure dose distribution of the second layer is the And the exposure amounts in the first, fifth, ninth and thirteenth scan steps corresponding to the exposure step for the first exposure step. The distribution of the divided exposure dose of the third layer and the fourth layer is also obtained by the same method. Therefore, the divided exposure dose distribution of the n-th layer can be obtained by summing up the exposure amounts in each scan step corresponding to the exposure process for the n-th layer.

5A to 5F show a process in which the divided exposure dose distribution of each layer is determined by an exposure process of each scan step. When the reflection area w of the DMDs 30 and 35 of the optical modulator corresponds to the target exposure area 1, that is, the ratio of the reflection area w overlapping with the target exposure area 1, The case where the operating state of the DMDs 30 and 35 is turned on when the current value becomes 50% or more of the region w will be described as an example. Here, the DMDs 30 and 35 of the optical modulator move in the direction of the arrow relative to the substrate 10. Here, the DMDs 30 and 35 and the target exposure area are limited to a two-dimensional sectional view for convenience of explanation. w denotes the length of the reflection area of the DMD, and 1 denotes the length of the target exposure area. The length of the DMD and the target exposure area may be expressed as the width of the DMD and the target exposure area.

5A, the length of a portion where the reflection area of the first DMD 30 overlaps with the target exposure area 1 corresponds to 50% of the length w of the first DMD 30, The operation is in an on state. On the other hand, since the reflection area of the second DMD 35 and the target exposure area 1 do not overlap yet, the operation of the second DMD 35 is in the OFF state.

Referring to FIG. 5B, the length of a portion where the reflection area of the first DMD 30 overlaps with the target exposure area 1 corresponds to 100% of the length of the first DMD 30, . The operation of the second DMD 35 is still off because the length of the portion where the reflection area of the second DMD 35 overlaps with the target exposure area 1 is still smaller than 50% of the length of the second DMD 35. [

Referring to FIG. 5C, when the length of a portion where the reflection area of the first and second DMDs 30 and 35 overlaps with the target exposure area 1 corresponds to 50% or more of the lengths of the first and second DMDs 30 and 35 The operation of the first DMD 30 is still in the ON state and the operation of the second DMD 35 is changed from the OFF state to the ON state.

5D, when the length of a portion where the reflection area of the first and second DMDs 30 and 35 overlaps with the target exposure area 1 corresponds to 50% or more of the lengths of the first and second DMDs 30 and 35 The operations of the first and second DMDs 30 and 35 are kept on.

5E, since the length of the portion where the reflection area of the first DMD 30 overlaps with the target exposure area 1 is smaller than 50% of the length of the first DMD 30, the operation of the first DMD 30 is in the OFF state . On the other hand, since the length of the portion where the reflection area of the second DMD 35 overlaps with the target exposure area 1 is larger than 50% of the length of the second DMD 35, the operation of the second DMD 35 is kept on.

Referring to FIG. 5F, since there is no portion where the reflection area of the first DMD 30 overlaps with the target exposure area 1, the operation of the first DMD 30 is kept off. On the other hand, since the length of the portion where the reflection area of the second DMD 35 overlaps with the target exposure area 1 is about 50% of the length of the second DMD 35, the operation of the second DMD 35 is kept on. The operation of the first and second DMDs 30 and 35 is completed because both the reflection area of the first and second DMDs 30 and 35 overlap with the target exposure area 1 Off state.

Fig. 6 shows the distribution of the exposure dose I (exposure energy) obtained by accumulating the respective exposure amounts in the exposure steps of the respective scan steps in Figs. 5A to 5F.

Referring to FIG. 6, it can be seen that there is an energy slope in the cumulative divided exposure dose distribution. The energy gradient region exists at both boundary lines of the target exposure region (1). It can be seen that the length of the energy gradient section is the same as the length (w) of the reflection area of the DMD (30, 35 in FIG. 5A). Since there is an energy gradient section in the cumulative divided exposure dose distribution, the cumulative exposure dose distribution in which all of the divided exposure dose distributions for all the layers are accumulated can be different from the target exposure dose distribution to be achieved.

일 때의 x 값이다.7 shows the accumulated exposure amount distribution Y (x), the target exposure amount distribution E (x), and the corrected target exposure amount distribution E '(x), which are accumulated cumulative divided exposure amount distribution and divided exposure amount distribution of each layer . For convenience of explanation, the cumulative exposure dose distribution Y (x) and the target exposure dose distribution E (x) are simplified by a function relating to x. Further, the target exposure amount distribution E (x) is translated in the x-axis direction so that the x-axis intercept is w / 2, and is modified to satisfy the following equation (5). Only the section x in which the target exposure amount distribution E (x) is a monotone increasing function will be described. Here, d is an x value when the target exposure dose distribution E (x) has a maximum value, that is,

X < / RTI >

인 사다리꼴 형상이며, i번째의 분할 노광량 분포는 수학식 6과 같이 정리할 수 있다. 여기에서, 각(脚)은 사다리꼴에서 서로 평행하지 않은 두 변 중 한 변을 의미한다.As a result of exposure for each divided exposure dose distribution divided into n layers, the divided exposure dose distribution is obtained by dividing the slope of each (leg)

, And the i-th divided exposure dose distribution can be summarized as shown in Equation (6). Here, each leg represents one of two sides that are not parallel to each other in a trapezoid.

로 표기하고 수학식 7과 같이 정리될 수 있다.The cumulative exposure dose distribution for the first to i-th divided exposure dose distributions

And can be summarized as Equation (7).

For convenience of explanation, the cumulative exposure dose distribution Y (x) for all the layers is summarized by dividing x by three sections of 0 ≤ x <d, d ≤ x <w and d ≤ x <w + d.

Referring to FIG. 7, the cumulative exposure amount distribution Y (x) for the first section (0? X <d) is summarized as Equation (8).

이고, 누적 노광량 분포를 무한 개(n→∞)로 분할한다고 가정하면 다음 수학식 9와 같이 정리될 수 있다.Equation (8)

And the cumulative exposure dose distribution is divided into an infinite number (n → ∞), the following equation (9) can be obtained.

Therefore, Equation (8) can be summarized as Equation (10) with respect to the first section.

In the same way, the cumulative exposure dose distribution Y (x) in the second section (d? X <w) and the third section (d? X <w + d) have.

Equations 10 to 12 are calculated assuming that d < w.

및

는 수학식 10 및 수학식 12와 동일한 결과로 정리되고, 제2구간(w ≤ x < d)에 대한 누적 노광량 분포

는 다음 수학식 13과 같이 정리될 수 있다.On the other hand, the cumulative exposure dose distribution Y (x) is obtained for the case of d? W in the same manner as described above. x is divided into three sections: 0 ≤ x <w, w ≤ x <d and d ≤ x <d + w. Cumulative exposure dose distribution for the first section (0? X <w) and the third section (d? X <d + w)

And

Are summarized in the same manner as in Equations (10) and (12), and the cumulative exposure amount distribution for the second section (w < x &lt; d)

Can be rearranged as shown in the following equation (13).

의 형태로 표현될 수 있는 목표 노광량 분포 E(x)에 대해서 무수히 많은 수의 분할 노광량 분포로 분할하고, 각각에 대하여 노광하여 그 결과를 모든 층에 대해 누적하여 얻어진 누적 노광량 분포는 d < w인 경우 수학식 10, 11 및 12와 같이, d ≥ w인 경우에는 수학식 10, 12 및 13과 같이 Y(x)로 표현될 수 있다.like this

The cumulative exposure dose distribution obtained by dividing the target exposure dose distribution E (x), which can be expressed in the form of the exposure dose distribution E (x), into a large number of divided exposure dose distributions, (10), (11), and (12), when d? W, it can be expressed as Y (x) as shown in Equations (10), (12), and (13).

This is because if the actual exposure process is performed based on the target target exposure dose distribution E (x), the result is realized according to the cumulative exposure dose distribution Y (x). Therefore, in order to realize the exposure result equal to the targeted target exposure dose distribution E (x), it is necessary to correct the exposure dose for the target exposure dose distribution E (x).

A method for calculating the corrected target exposure dose distribution E '(x) will be described for the first section (0 < x &lt; d). In Equation (10), the target exposure amount distribution E (x) is implemented as the cumulative exposure amount distribution Y ¹ (x) in the first section as shown in the following Equation (14). However, considering that the exposure dose distribution to be actually achieved as the exposure result is the target exposure dose distribution E (x), if the exposure is based on the corrected exposure dose distribution E '(x), the cumulative exposure dose distribution Y ¹ (X) of the target exposure dose E (x).

That is, the cumulative exposure amount distribution Y ¹ (x) is made to coincide with the target target exposure amount distribution E (x) as shown in the following expression (15), and the corrected exposure amount distribution E '(x) can be obtained.

임을 감안하면, 보정된 노광량 분포 E'(x)는 다음 수학식 16과 같다.When the exposure process is performed on the corrected target exposure dose distribution E '(x) obtained by the optical cumulative inverse transformation in this way, the result coincides with the target exposure dose distribution E (x) originally intended to be implemented. In Equation 15, if the target exposure dose distribution E (x) is

, The corrected exposure dose distribution E '(x) is expressed by the following equation (16).

와 같이 실제로 노광이 구현되게 하기 위해서는, 보정된 목표 노광량 분포

를 기초로 노광 공정이 수행되어야 함을 알 수 있다. 제2구간(d ≤ x < w) 및 제3구간(d ≤ x < w + d)에 대한 보정된 목표 노광량 분포 E'(x)는 상기 제1구간에서와 같이 광 누적 역변환을 이용하여 산출할 수 있다.Thus, the target target exposure dose distribution

In order to realize the actual exposure, the corrected target exposure amount distribution

It is understood that the exposure process should be performed. The corrected target exposure dose distribution E '(x) for the second section (d? X <w) and the third section (d? X <w + d) is calculated using the optical cumulative inverse transform as in the first section can do.

The present embodiment may further include a step of offset-correcting the target exposure amount distribution E (x) in order to perform finer processing. The target exposure amount distribution E (x) and the cumulative exposure amount distribution Y (x) can be corrected by offset-correcting the respective divided exposure amount distributions. This correction step is performed in order to prevent deterioration of the pattern due to the energy gradient period in the divided exposure dose distribution and obtain the target three-dimensional structure as described above. The corrected target exposure dose distribution E '(x) is calculated using equations (10), (11) and (12) when the target exposure dose distribution E Can be obtained by calibrating. That is, the corrected target exposure amount distribution E '(x) can be obtained by comparing the target exposure amount distribution E (x) with the cumulative exposure amount distribution Y (x) and performing offset correction on the divided exposure amount distribution by the difference value. 7, when the corrected target exposure amount distribution E '(x) is compared with the target exposure amount distribution E (x) and the cumulative exposure amount distribution Y (x), the exposure area becomes smaller by w / 2 for the first layer, For the nth layer, the exposure area must be enlarged by w / 2.

을 만족하는 x의 값이 x_{E (L)}이고, 누적 노광량 분포 Y(x)에 대해서 같은 노광량 값을 만족하는 즉,

를 만족하는 x의 값을 x_{Y (L)}이라고 할 때, 보정된 노광량 분포 E'(x)에 관해

를 만족하는 x 값, x_{E' (L)}은 다음 수학식 17과 같이 구할 수 있다. 여기에서, 제L층에 대한 오프셋 양 즉 제L오프셋 양은 (x_E(L)-x_Y(L))이 된다.A more detailed offset correction will be described with reference to FIG. The cumulative divided exposure amount of the Lth layer in the target exposure amount distribution E (x)

(X) is x _{E (L)} , and the cumulative exposure dose distribution Y (x) satisfies the same exposure amount value, that is,

With respect to the values of x which satisfies x _Y, the corrected exposure amount distribution E '(x) to that _(L)

X _{E ' (L)} can be obtained by the following equation (17). Here, the offset amount, i.e., the Lth offset amount with respect to the Lth layer becomes (x _{E (L)} -x _{Y (L)} ).

Considering that the offset correction for the target exposure dose distribution E (x) is implemented as a correction to the value of the divided exposure dose distribution for each layer, the above equation (17) can be said to be a correction to an approximate value, but a preferable method.

를 만족하며 여기에서 x_E(1)=w/2이고 x_{Y (1)}=0이므로, 제1오프셋 양

만큼 보정되어

을 만족하게 된다. 마찬가지로 제n층의 분할 노광량 분포에 대해서는 다음식

를 만족하며 여기에서 x_E(n)=w/2+d이고 x_{Y (n)}=w+d이므로, 제n오프셋 양

만큼 보정되어

를 만족하게 된다. 이렇게 오프셋 보정 단계를 거쳐 보정된 목표 노광량 분포 E'(x)에 따라 노광 공정이 수행되면, 누적 노광량 분포 Y(x)가 원래 노광하고자 했던 목표 노광량 분포 E(x)와 일치할 수 있게 된다.With respect to the divided exposure amount distribution of the first layer according to the above expression (17)

, Where x _{E (1)} = w / 2 and x _{Y (1)} = 0, the first offset amount

As much as

. Similarly, with respect to the divided exposure dose distribution of the n-th layer,

, Where x _{E (n)} = w / 2 + d and x _{Y (n)} = w + d,

As much as

. When the exposure process is performed according to the target exposure dose distribution E '(x) corrected through the offset correction step, the cumulative exposure dose distribution Y (x) can coincide with the target exposure dose distribution E (x) originally intended to be exposed.

9 is a schematic diagram of a digital three-dimensional lithography apparatus according to another embodiment of the present invention.

Referring to FIG. 9, a digital three-dimensional lithography apparatus 100 for use in a digital three-dimensional lithography method according to an embodiment of the present invention is disclosed. The digital three-dimensional lithography apparatus 100 may include a light source unit 40, an optical modulator 50, and a control unit 60. The optical modulator 50 reflects the light emitted from the light source unit 40 and irradiates the photoresist film 20 on the substrate 10. In addition, the optical modulator 50 may include a plurality of digital micromirror devices, which may be arranged in an array form. The control unit 60 controls the optical modulator 50 according to the corrected target exposure amount distribution E '(x). The corrected target exposure amount distribution E '(x) is determined based on the target exposure amount distribution E (x), the divided exposure amount distribution and the cumulative exposure amount distribution Y (x). That is, the control unit 60 determines the amount of offset based on the difference between the target exposure amount distribution E (x) and the cumulative exposure amount distribution Y (x), and corrects the target exposure amount distribution E (x) The target exposure dose distribution E '(x) can be determined. The method of determining the corrected target exposure dose distribution E '(x) is the same as that described in the digital three-dimensional lithography method described above, and thus a detailed description thereof will be omitted.

The digital three-dimensional lithography method of the present invention has been described with reference to the embodiments shown in the drawings to facilitate understanding of the present invention. However, those skilled in the art will appreciate that various modifications and equivalent implementations You will understand that an example is possible. Accordingly, the true scope of the present invention should be determined by the appended claims.

10: substrate 20: photosensitive film
30: first DMD 35: second DMD
40: light source 50: optical modulator
60:
l: length of the target exposure area w: length of the reflection area

Claims (8)

Determining a target exposure dose distribution based on the characteristics of the photoresist formed on the substrate and the shape of the three-dimensional structure to be fabricated;
The control unit offset-corrects the target exposure dose distribution to determine a corrected target exposure dose distribution;
Forming divided exposure amount distributions divided into n (n is a natural number of 1 or more) layers based on the corrected target exposure amount distribution;
Selecting one of the n divided exposure dose distributions in each scan step and setting the selected pattern as a pattern to be exposed;
Controlling a light modulator according to the pattern set in each scan step to form a digital mask; And
And exposing the photoresist film based on the digital mask,
The step of determining the corrected target exposure dose distribution
Determining, by the control unit, divided exposure amount distributions divided into n (n is a natural number of 1 or more) layers based on the target exposure amount distribution;
Summing the divided exposure dose distributions to determine an accumulated exposure dose distribution; And
Determining an offset amount based on a difference between the target exposure amount distribution and the cumulative exposure amount distribution, and offset-correcting the target exposure amount distribution by the offset amount. delete The method according to claim 1,
Wherein the offset correction step performs offset correction to reduce the first exposure amount distribution of the first layer among the divided exposure amount distributions divided by the n number of layers by a first offset amount, And the offset correction is performed so as to increase the size of the digital three-dimensional lithography. The method according to claim 1,
Wherein the offset correction step performs offset correction on the Lth layer (L is a natural number smaller than 1 and a natural number smaller than n) by a Lth offset amount with respect to a divided exposure amount distribution. The method according to claim 1,
Wherein the n divided exposure dose distributions are formed by n two-dimensional horizontal cross sections obtained by evenly dividing the target exposure dose distribution into n layers and selecting one horizontal section belonging to each layer with respect to the divided n layers Wherein the digital three-dimensional lithography method is characterized by: The method according to claim 1,
Wherein the pattern to be exposed in each of the scan steps is grouped into n groups of all the scan steps and one of the n divided exposure dose distributions is grouped into n groups of scan steps and n divided exposure dose distributions, And the selected three-dimensional lithography method is selected and set. A light source;
An optical modulator that includes a plurality of digital micromirror elements and reflects the light incident from the light source part and irradiates the light to the photoresist film on the substrate; And
And a control unit for determining a corrected target exposure amount distribution based on the target exposure amount distribution, the divided exposure amount distribution, and the cumulative exposure amount distribution, and controlling the optical modulator according to the corrected target exposure amount distribution,
Wherein the control unit determines an offset amount based on a difference between the target exposure amount distribution and the cumulative exposure amount distribution and determines the corrected target exposure amount distribution by offset correction of the target exposure amount distribution by the offset amount. Dimensional lithography apparatus. delete

Images