JPH1116808A - Pattern exposure apparatus and pattern transfer distortion correction method thereof - Google Patents

Abstract

[PROBLEMS] To prevent distortion of a projection lens for performing pattern transfer of a conventional pattern exposure apparatus, which cannot be eliminated, and that a plurality of lenses are combined to cancel each other's aberrations and minimize the aberration. Therefore, the pattern transfer distortion cannot be completely corrected, and the distortion greatly affects as the pattern becomes finer. The present invention includes a reticle (11) whose pattern can be electrically moved by using a liquid crystal or the like, and a pattern based on distortion of a projection lens (4) in advance so that a completely distortion-free pattern is transferred. Data storage unit 1 by intentionally distorting
3, a pattern exposure apparatus that transfers a pattern light transmitted through a reticle 11 on which a pattern based on data selected at the time of exposure is drawn and corrected as a result of distortion of the projection lens 4 as a pattern without distortion. This is the pattern transfer distortion correction method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for exposing a pattern of a semiconductor device used in a photolithography technique, and more particularly to a pattern exposure apparatus for correcting a pattern transfer distortion and a method for correcting the pattern transfer distortion.

[0002]

2. Description of the Related Art As the miniaturization of semiconductor devices progresses,
The pattern exposure used in the photolithography technique is mostly performed by a stepper device.

As shown in FIG. 4, for example, this stepper apparatus has an illumination system 2 using an ultra-high pressure mercury lamp 1 as a light source, an ultra-high resolution lens system including a condenser lens 3 and a reduction projection lens 4, and the like. Reticle 5 on which patterns such as circuit patterns set interchangeably between are drawn
And a two-dimensionally movable X on which the semiconductor wafer 6 is placed.
It is composed of a Y stage 7. With this configuration, the focused pattern light transmitted through the reticle 5 is reduced and transferred onto the semiconductor wafer 6 in an area of 15 to 20 mm square, and the XY stage 7
Then, the semiconductor wafer 7 is moved, and the entire surface of the semiconductor wafer is sequentially and repeatedly subjected to pattern transfer exposure.

[0004]

The pattern exposure apparatus which draws a pattern on the semiconductor wafer 6 using photolithography technology is not limited to the above-described stepper apparatus, but focuses light passing through the reticle 5, that is, Reticle 5
An optical projection lens for reducing and projecting a pattern to be drawn on the camera.

[0005] The performance of the projection lens depends on the resolving power and the depth of focus, and in particular, a problem of distortion occurs. This distortion is one of Seidel aberrations in which an image of a plane object perpendicular to the optical axis is not similar in an image plane perpendicular to the optical axis. This distortion occurs because the lateral magnification of the lens is not uniform in the image plane.

FIG. 5 shows an example in which an image is distorted. FIG.
(A) is a normal image without distortion, and corresponds to the pattern drawn on the reticle 5. When this is converged and projected by the projection lens 4, the barrel-shaped distortion as shown in FIG. 5B and the pincushion-shaped distortion as shown in FIG. 5C are combined. There is distortion.

When such distortion occurs, the reticle 5
Is vertically focused by the projection lens 4 and projected onto the semiconductor wafer 6, the pattern of the reticle 5 is distorted and projected onto the semiconductor wafer 6.

[0008] Since it is difficult to eliminate this distortion with a single lens, generally, a plurality of lenses are combined.
The aberrations are canceled to each other so that the aberrations are minimized. However, actually, not only the distortion but also other aberrations and the inclination and displacement of the axis are combined to have an adverse effect. For this reason, it is impossible to completely correct the positional deviation only by a combination of a plurality of lenses.

[0009] Therefore, not only is it laborious to manufacture a projection lens, but it is not possible to completely correct the pattern transfer distortion due to the distortion of the projection lens, and the distortion increases as the pattern becomes finer. Will have an effect.

Accordingly, the present invention employs a deformable reticle to form a pattern to be drawn, and forms a pattern which is deformed so as to be corrected by the displacement of the projection lens due to distortion or the like.
At the time of exposure, the deformed pattern is drawn on a reticle, and the transferred pattern returns to its original state due to distortion due to distortion of the projection lens, etc., and a transfer pattern without displacement can be obtained. It is an object of the present invention to provide an apparatus and a method for correcting a pattern transfer distortion thereof.

[0011]

In order to achieve the above object, the present invention provides a pattern exposure apparatus for transmitting a light to a pattern drawn on a reticle, projecting the pattern, and transferring a pattern similar to the pattern. A pattern in which the reticle is capable of electrically deforming a pattern and includes a substance composed of a raster matrix made of a material capable of being electrically transmissive / non-transmissive, and electrically deforming the reticle pattern. There is provided a pattern exposure apparatus comprising: a driving unit; a data storage unit for storing information on the pattern; and a reticle data transmission unit for supplying information selected from the storage unit to the pattern driving unit.

According to the present invention, there is provided a pattern exposure distortion correcting method for a pattern exposure apparatus for projecting light by transmitting light to a pattern drawn on a reticle and transferring a pattern similar to the pattern. Provided is a pattern transfer distortion correction method for deforming an original pattern drawn on the reticle such that a transfer pattern projected by a projection lens onto the original pattern is similar.

The pattern exposure apparatus and the pattern transfer distortion correcting method having the above-described configurations are directed to a method in which a material composed of a raster matrix made of a material which can be switched between electrically transparent and non-transparent, such as a liquid crystal or the like, is used. The reticle is provided with a reticle that can deform the pattern in a uniform manner, so that the transfer pattern deformed by the distortion of the projection lens in advance is similar to the original pattern without distortion so that a transfer pattern without distortion can be obtained completely. The pattern drawn above is intentionally deformed, information including the pattern is stored as data, and a pattern deformed by the data selected as necessary at the time of exposure is drawn on the reticle, The pattern light transmitted through the reticle is distorted as corrected by the distortion of the projection lens, resulting in a transfer pattern without distortion. It is transcribed as.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an example of the configuration of a pattern exposure apparatus according to an embodiment of the present invention. Here, in the present embodiment, the same components as those shown in the device configuration shown in FIG. 4 are denoted by the same reference numerals, and the features of the present invention will be described. In the present embodiment, an original pattern without distortion is referred to as an original pattern, a pattern projected by a projection lens is referred to as a transfer pattern, and a pattern drawn and deformed by reticle is referred to as a deformed pattern.

This pattern exposure apparatus uses an ultra-high pressure mercury lamp 1
, A light source, and an illumination system 2 including a mirror and a shutter
And an ultra-high-resolution lens system including a condenser lens 3 and a reduction projection lens 4 and the like, and a reticle 11 which is set between these lenses and whose pattern can be deformed by an electric signal.
A driver unit 12 for causing the reticle 11 to draw a deformed pattern or an original pattern, and a data storage unit 13 for storing a plurality of data including the deformed pattern and the original pattern
And the driver unit 12 and the data storage unit 13
Control unit 14 for drawing a desired pattern on reticle 11 and deforming the pattern drawn on reticle 11
An XY stage 7 on which a semiconductor wafer is placed and which can move two-dimensionally, and an imaging device 1 comprising a CCD or the like mounted on the XY stage 7 and reading a projected transfer pattern.
5 and a display unit 16 for displaying information such as patterns and transfer patterns on the screen.

The image pickup device 15 is attached to a position where the semiconductor wafer is mounted on the XY stage 7 when correcting the distortion of the transfer pattern to be transferred to the semiconductor wafer, and transfers the data of the projected transfer pattern. Take it into the control unit 14.

The reticle 11 is made of a material that can be electrically switched between transmission and non-transmission, for example, micro cells such as a liquid crystal shutter are arranged in a matrix, and transmission / non-transmission of light is controlled by an electric signal. Thus, the pattern (composition) can be electrically deformed. As for the pattern drawn on the reticle 11, data including a desired pattern is read from the data storage unit 13 as liquid crystal drive information under the control of the control unit 14, and the driver unit 12 is driven to form the reticle 11. Further, at the time of pattern transfer distortion correction, as will be described later, under the control of the control unit 14, the transfer pattern obtained by the image sensor 15
The driver unit 1 is compared with the pattern formed on the reticle 11 so that the transfer pattern becomes a pattern without distortion.
2, the pattern of the reticle 11 is displaced.
In the present embodiment, a liquid crystal shutter is used as an example of the reticle, but is not necessarily limited to liquid crystal.

Next, a description will be given of a method of correcting a pattern transfer distortion in the pattern exposure apparatus configured as described above.

First, the outline of the pattern transfer distortion correcting method will be described.

In the conventional pattern transfer distortion correcting method, for example, when a square geometric pattern in which a plurality of squares are connected in a matrix is adopted as a pattern without distortion, the transfer pattern focused and projected by the projection lens is used as the original. In order to get closer to the square geometric pattern, the correction was performed by changing a plurality of lenses.

In the present invention, for example, a reticle 11 on which the above-mentioned square geometric pattern is drawn is set, and this square geometric pattern is projected onto a plane by a projection lens whose distortion has not been corrected. Naturally, the transfer pattern projected on the plane is distorted in any direction.

Next, the driver unit 12 is driven under the control of the control unit 14, and the distorted portion of the pattern drawn by the liquid crystal of the reticle 11 is electrically moved, so that the transfer pattern has a square geometry without distortion. Correct so that it becomes a pattern. The pattern of the reticle 11 obtained at the time of this correction is stored in the data storage unit 13.

That is, the square geometric pattern stored in the data storage unit 13 is actually stored in a distorted pattern. When this pattern is used, the selected distorted pattern is read out to the reticle 11 again, drawn, and projected by the projection lens 4. When the distorted pattern is distorted and corrected, a square geometric pattern without distortion is obtained. Is transcribed as

As described above, by storing a distorted pattern including the distortion of the projection lens as data in advance, it is possible to replace the reticle without replacing the reticle each time as in the conventional case, and to replace the reticle with the data. Not many patterns can be transferred to a semiconductor wafer.

Next, a method of correcting the actual pattern transfer will be described.

As shown in FIG. 2A, when the pattern to be transferred is the above-described square geometric pattern as an example,
Each intersection (square grid point) is defined as y0, y1, y2,
, Yn-1, yn, yn + 1, x0, x1, x2, ..., xn-1,
Given an address of xn, xn + 1, a certain point (xn, y
When n) is transferred to a certain plane by the projection lens, it moves to a displacement point (Xn, Yn) due to distortion as shown in FIG.

When this relationship is expressed by an equation,

(Equation 2) Becomes However,

(Equation 3) Is the displacement due to distortion. The displacement amount is represented by a vector amount, and the square geometric pattern to be stored becomes a square geometric pattern that is deformed and distorted so as to cancel the distortion.

When returning a distorted pattern such as that shown in FIG. 3A from the data storage unit 13 to the reticle 11 to a transfer pattern without distortion as shown in FIG.

(Equation 4) Can be represented by Therefore,

(Equation 5) Or

(Equation 6) It can be expressed as. Also,

(Equation 7) It can be expressed as. However,

(Equation 8) It is. Therefore,

(Equation 9) Here, approximately, assuming that M: N: O: P = Q: R: S: T,

(Equation 10) Here, m, n, o, and p are eigenvalues of M, N, O, and P. Using the inverse of this determinant,

[Equation 11] Becomes This inverse matrix can be obtained from n = 0 to m (where m is the maximum number of grids), and the coordinates on the original reticle can be obtained so as to be displaced on the square grid points after exposure.

As described above, according to this embodiment, when a desired pattern is transferred to a semiconductor wafer,
In order to completely eliminate distortion, the pattern is intentionally distorted and stored in advance so that it is corrected by the amount of displacement that is distorted by the projection lens, and since it is read out and used, the distortion due to the projection lens has no effect. A desired transfer pattern without distortion and without distortion can be projected on the semiconductor wafer.

In this embodiment, since data is created with distortion characteristics peculiar to each projection lens, when the projection lens is replaced with a new projection lens, a transfer pattern is created again according to the amount of distortion. It needs to be stored again. The update of such a transfer pattern is performed by programming the above-described arithmetic processing in the control unit 14, and when the projection lens or the like is replaced, the data storage unit 13 is automatically or instructed by an operator. The deformed pattern to be described on the reticle stored in the reticle is read out, and again, the deformed pattern re-deformed according to the distortion amount of the new interchangeable lens may be updated and stored sequentially, or only the selected pattern may be stored. May be updated, or the deformation pattern may be manually updated individually.

[0032]

According to the present invention as described in detail above,
Using a liquid crystal, a pattern to be drawn by an electric signal using a deformable reticle is adopted, and a distorted pattern is stored in advance so that it is corrected by the displacement due to the distortion of the projection lens, and it is distorted when used. When a pattern is drawn on a reticle, the transferred pattern returns to its original state by the distortion due to the distortion of the projection lens, and a transfer pattern without distortion can be obtained, and a pattern transfer distortion correction method thereof. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a pattern exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for describing coordinate points displaced by distortion due to a lens according to the embodiment.

FIG. 3 is a diagram for explaining a case where a distorted pattern stored in a storage unit is transferred to a pattern without distortion according to the embodiment;

FIG. 4 is a diagram illustrating a configuration example of a conventional stepper device.

FIG. 5 is a diagram showing an example of an image distorted by distortion of a projection lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultra-high pressure mercury lamp 2 ... Illumination system 3 ... Condenser lens 4 ... Reduction projection lens (projection lens) 6 ... Semiconductor wafer 7 ... XY stage 11 ... Rectil 12 ... Driver unit 13 ... Data storage unit 14 ... Control unit 15 ... Imaging element 16 Display unit

Claims (6)

[Claims] 1. A pattern exposure apparatus for transmitting and projecting light onto a pattern drawn on a reticle and transferring a pattern similar to the pattern, wherein the reticle is capable of electrically deforming the pattern. A pattern driving means for electrically deforming the reticle pattern, comprising a substance constituted by a raster matrix made of a material capable of selectively switching transmission / non-transmission; and a data storage unit for storing information relating to the pattern. A reticle data transmitting unit that supplies information selected from the storage unit to the pattern driving unit. 2. A reticle data transmitting means, comprising: a data storing means for storing a plurality of pattern data; a selecting means for selecting and reading out desired pattern data from the data storing means by a selection signal supplied from the outside; The pattern exposure apparatus according to claim 1, further comprising: 3. A pattern exposure apparatus for transmitting light to a pattern drawn on a reticle, projecting the light by a projection lens, and transferring a transfer pattern similar to the pattern on a plane, wherein the reticle electrically deforms the pattern. A pattern driving means for electrically deforming the reticle pattern, comprising: a material constituted by a raster matrix made of a material capable of switching between electrically transmissive and non-transmissive; Transfer pattern reading means for reading the transferred transfer pattern, comparing the transfer pattern obtained by the transfer pattern reading means and the original pattern without distortion originally drawn on the reticle, the transfer pattern is similar to the original pattern So that the pattern drawn on the reticle is deformed. A control unit for controlling a turn driving unit; a reticle controlled by the control unit, storing a plurality of pieces of information including a pattern deformed in the reticle, selecting information including a desired pattern, and supplying the selected information to the pattern driving unit. And a data transmission unit. 4. A control unit of the pattern exposure apparatus, wherein when the projection lens is replaced with a new projection lens,
Control means for performing control to sequentially update a plurality of deformed patterns stored in the reticle data transmission means so that a transfer pattern by projection of a new projection lens becomes similar to the original pattern by a predetermined programming. 4. The pattern exposure apparatus according to claim 3, comprising: 5. A pattern transfer distortion correction method of a pattern exposure apparatus for transmitting a light through a pattern drawn on a reticle and projecting the pattern, and transferring a pattern similar to the pattern, wherein the first original pattern drawn on the reticle is A pattern transfer distortion correction method, wherein an original pattern drawn on the reticle is deformed so that a transfer pattern projected by a projection lens is similar. 6. A pattern transfer distortion correction method of a pattern exposure apparatus for transmitting light through a pattern drawn on a reticle and projecting the pattern, and transferring a pattern similar to the pattern, wherein a first original pattern drawn on a reticle is corrected. A transfer pattern projected by a projection lens as a lattice pattern is taken in, the original pattern and the transfer pattern are compared, and when the transfer pattern is similar to the original pattern, the reticle pattern is expressed as A pattern transfer distortion correction method, wherein the pattern transfer distortion is corrected based on