JPH08298236A - Pattern exposure method and device - Google Patents

Abstract

PURPOSE: Not only to dispense with an aligning pattern but also to align various component patterns accurately by a method wherein a following pattern is aligned comparing a first image data with the image data of an image- recognized following pattern. CONSTITUTION: A difference between the accurate position coordinates of a first original pattern ICa and a second pattern ICb and the actual position coordinates of the pattern ICa and ICb detected by an optical system is calculated with a data processing device. If the difference is zero, the patterns ICa and ICb are coincident with each other. If the difference is not zero, the movement of a drive motor which drives a stage 6 is determined to control the stage 6 so as to make the difference zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION For example, when manufacturing a semiconductor integrated circuit device (hereinafter simply referred to as "IC") in which a large number of electronic circuits are formed, various types of IC patterns are formed on the surface of a semiconductor wafer. An IC pattern is exposed and formed by superposing patterns, and the present invention relates to an improvement of such a pattern exposure method and apparatus.

[0002]

2. Description of the Related Art First, a conventional pattern exposure method will be described with reference to FIGS. FIG. 3 is a plan view of a reticle on which a first IC pattern is drawn. FIG. 3A shows an original pattern of the first pattern, FIG. 3B shows a wafer alignment mark, and FIG. C indicates a conventional reticle in which a pattern in which the first pattern and the wafer alignment mark are combined is drawn, and FIG.
FIG. 9A is a view for explaining an exposure method of a pattern in which the second original pattern is aligned with the first original pattern of the C pattern, and FIG. A is a plane of the second pattern of the IC pattern on the reticle. FIG. 5B is a plan view of a pattern in which the second pattern is combined with the first pattern, and FIG. 5 shows the positional deviation of the pattern when both patterns shown in FIG. 4B are combined. In FIG. A, the second pattern is vertical with respect to the first original pattern, and in FIG. B, the second pattern is horizontal with respect to the first original pattern. Figure C shows first
FIG. 11 is a plan view showing a state in which the second pattern is displaced in the diagonally rightward and downward direction with respect to the th original pattern.

In the case of manufacturing an IC, conventionally, various kinds of patterns forming an IC pattern are exposed on a resist applied on the surface of a semiconductor wafer in sequence while precisely superposing them to perform surface treatment to manufacture an IC. are doing. In order to guarantee the overlay accuracy of various patterns, a conventional pattern exposure apparatus (hereinafter simply referred to as “exposure apparatus”) has a wafer alignment mark or a lens through alignment mark on the scribe line between the patterns of the reticle. It is necessary to form a special mark for alignment called.

For example, as shown in FIG. 3A, the original pattern ICa of the first pattern which constitutes one element of the IC pattern and the alignment marks PXa and Y in the X-axis direction as shown in FIG. 3B. It is necessary to prepare a reticle R that is a wafer alignment mark composed of the axial alignment mark PYa and the alignment mark Pa so that the alignment mark Pa is located on the scribe line. . This synthetic pattern is assumed to be IC
The first pattern P ₁ of the pattern is set, and the original pattern ICa drawn on the _first pattern P ₁ is set as the first original pattern.

Such a first original pattern ICa
Further, when the pattern ICb of the _second pattern P ₂ as shown in FIG. 4A is superposed so as to have the accurate positional relationship as shown in FIG. 4B, as shown in FIG. The second pattern ICb is vertical with respect to the first original pattern ICa, and the second pattern ICb is horizontal with respect to the first original pattern ICa, as shown in FIG. Then, as shown in FIG. 6C, the position of the pattern ICb with respect to the original pattern ICa is accurately determined so that the second pattern ICb is not displaced in the oblique direction with respect to the first original pattern ICa. There is a need to.

In the prior art pattern exposure method and apparatus, a first original pattern I is formed on the surface of a semiconductor wafer.
After forming Ca, the alignment mark P shown in FIG.
It is considered that the position of the first original pattern ICa is also fixed by detecting a with a dedicated detection device provided in the exposure apparatus, and by fixing this, the second original pattern ICa is located at that position. By forming the above, it is ensured that there is no misalignment between the first original pattern ICa and the second original pattern ICa as shown in FIG.

[0007]

However, in this exposure method, the alignment marks Pa, Pb ... Pn are used.
Must be set at the position required by the detection device for the alignment pattern of the exposure device, that is, the position that can be detected by the detection device, as described above, so that the number and position are limited.
Therefore, this restriction is one of the restrictions on the layout design of the element pattern at various stages of forming the IC pattern, and reduces the degree of freedom in the layout design of the element pattern. In addition, the first original pattern ICa and the second
Guarantee of overlay accuracy with the second pattern ICb, second
Guarantee of the overlay accuracy of the third pattern ICb and the third original pattern ICc, and similarly, guarantee of the overlay accuracy of the (N-1) th pattern IC _N-1 and the Nth pattern IC _N , Alignment marks Pa, Pb ...
-It is indirect via Pn. Therefore,
The misalignment of the overlapping position occurs at each stage, resulting in a decrease in yield.

Therefore, an object of the present invention is to solve the above-mentioned problems and to obtain an exposure method and an exposure apparatus which can eliminate the need for a positioning pattern and can accurately position each element pattern. is there.

[0009]

Therefore, the pattern exposure method of the present invention is already applied to the case where a plurality of patterns are sequentially exposed and formed on the exposed surface of a semiconductor wafer which is one of the surface-treated workpieces. The first pattern formed by exposure and pattern recognition is converted into image data, and the next pattern is aligned while comparing the image data with the image data of the next pattern recognized. , The above-mentioned subject was solved.

Further, as an exposure apparatus for realizing the pattern exposure method, a semiconductor wafer which is a surface-treated workpiece is placed, and the exposed surface of the semiconductor wafer is set in the X-axis direction,
A stage supported so as to be rotatable in the Y-axis direction and the horizontal plane, a drive motor for driving the stage in the X-axis direction and the Y-axis direction, and a rotation drive motor for driving the stage in the horizontal plane, An exposure optical device including a light source and an exposure optical system for sequentially exposing and forming N (N is an integer of 1 or more) patterns on an exposed surface of a semiconductor wafer placed on a stage, and the exposure optical device. The image of the first pattern of the Nth pattern formed by the image recognition is performed, and the coordinates of an arbitrary point serving as a reference when the second pattern is superposed on the first pattern. An image data processing device that digitizes the data, a data processing device that compares the coordinate value of the image data processing device with the coordinate value of the second pattern, and a data processing device that responds to the output signal of the data processing device. And a motor drive control device and for controlling the respective driving motor so as to align the first th pattern and the second pattern Te realizes the exposure method.

[0011]

Therefore, when the exposure method and apparatus of the present invention are used, the degree of freedom in designing the reticle can be improved because the alignment pattern is not required.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the exposure method and exposure apparatus of the present invention will be described with reference to the drawings. 1 is a principle system diagram of an exposure apparatus according to an embodiment of the present invention, and FIG.
5 is a flowchart for explaining the operation of the exposure apparatus shown in FIG.

First, the structure of an exposure apparatus 1 according to an embodiment of the present invention will be described with reference to FIG. The exposure apparatus 1 is composed of an exposure optical system and an electronic control system. The exposure optical system includes a light source 2 and a half mirror 3 disposed below the light source 2 and inclined by 45 ° with respect to the optical axis of the light source 2.
An exposure optical device 4 further disposed below the half mirror 3, a reticle holder 5 further disposed below the exposure optical device 4, and further further disposed below the reticle holder 5. And the stage 6 provided. The stage 6 is provided with a mechanism whose surface is kept horizontal and whose height position can be adjusted, so that the surface of the semiconductor wafer S, which is a workpiece to be processed, can be kept horizontal. Further, an X-axis drive motor 7 for driving the stage 6 in the X-axis direction, a Y-axis drive motor 8 for driving the stage 6 in the Y-axis direction, and a rotary drive motor 9 for driving the stage 6 in a horizontal plane are connected to the stage 6. ing.

On the other hand, the electronic control system is arranged on an optical axis inclined by 45 ° with respect to the inclined surface of the half mirror 3, and an image data input device 10 such as a CCD is provided.
An image data processing processor 11 connected to the output side of the image data input device 10, a data processing device 12 connected to the image data processing processor 11, and a motor drive control device 13 connected to the output side. The output side of the motor drive control device 13 is connected to the X-axis drive motor 7, the Y-axis drive motor 8 and the rotation drive motor 9. The data input device 14 inputs the positional relationship data of the N-1th pattern and the Nth pattern, which should be originally, to the data processing device 12 in advance.

Next, the operation of the exposure apparatus 1 will be described with reference to FIG. First, the first reticle R having no alignment mark is mounted on the reticle holder 5, and the first original pattern shown in FIG. 3A is applied to the resist applied to the surface of the semiconductor wafer S by the light beam from the light source 2. The ICa is exposed and developed. In this case, the projection position of the original pattern ICa on the surface of the semiconductor wafer S should be determined as precisely as possible, but it is not absolutely necessary.

Next, the exposure apparatus 1 is started at step SP1 shown in the flow chart of FIG.
The image data input device 10 recognizes the image of the first original pattern ICa formed on the surface of the semiconductor wafer S, and the image data processor 11 in step SP2 performs image processing of the original pattern ICa. SP
In step 3, the second pattern ICb is digitized into the coordinates of an arbitrary point serving as a reference for superposition (step SP3).

Next, after mounting the second pattern ICb, which is to be superimposed on the first original pattern ICa, on the reticle holder 5, the exposure apparatus 1 starts again from step SP1.
And start the pattern ICb with the exposure optical device 4
Through step SP5 and step SP6, the image data input device 10 and the image data processor 11
Then, the image processing is performed to digitize the coordinates of the second pattern ICb so as to be compared with the coordinates of the reference point of the original pattern ICa.

Next, in step SP7, the position coordinates of the correct original positional relationship between the first original pattern ICa and the second pattern ICb and the first original pattern detected by the optical system, respectively. The difference θ between the actual position coordinates of ICa and the second pattern ICb is calculated using the data processing device 12, and if the difference θ is zero in step SP1, both patterns ICa and ICb match. As a result, the process proceeds to step SP11 to complete the alignment of the present invention. If the difference θ is not zero, the process proceeds to step SP9, and the motor drive control device 1
3, the operation amount of the drive motor for driving the stage 6 is determined, and the X-axis drive motor 7, Y is determined according to the operation amount.
The shaft drive motor 8 and the rotation drive motor 9 are driven to finely adjust the stage 6 and control is performed so that the difference θ becomes zero (step SP10), and the alignment of both patterns ICa and ICb is completed. Then, the original pattern ICa is formed on the semiconductor wafer S, and the pattern ICb is exposed and formed on the resist applied to the surface thereof.

Next, the third pattern I is formed on the surface of the semiconductor wafer S on which the second pattern ICb is formed.
When Cc is exposed and formed, the exposure apparatus 1 may be operated by following the same steps as described above, and a desired IC pattern can be accurately formed on the surface of the semiconductor wafer S.

[0020]

As described above, according to the pattern exposure method and apparatus of the present invention, restrictions on the reticle layout design can be eliminated, so that the degree of freedom in design is improved, and A number of excellent effects are obtained such that the overlay accuracy is also improved and therefore the manufacturing yield of ICs can be improved.

[Brief description of drawings]

FIG. 1 is a principle system diagram of an exposure apparatus that is an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the exposure apparatus shown in FIG.

FIG. 3 is a plan view of a reticle on which a first IC pattern is drawn, in which FIG. 3A shows an original pattern of the first pattern, FIG. 3B shows a wafer alignment mark, and FIG. FIG. C shows a conventional reticle in which a pattern obtained by combining the first pattern and the wafer alignment mark is drawn.

FIG. 4 is a diagram for explaining an exposure method of a pattern for aligning the second pattern with the first original pattern of the IC pattern, and FIG. 4A shows the IC pattern on the reticle. A top view of the second pattern,
FIG. 9B is a plan view of a pattern in which the first pattern and the second pattern are combined.

5A and 5B show positional shifts of the patterns when the two patterns shown in FIG. 4B are combined, and FIG. 5A shows the second original pattern in the vertical direction with respect to the first original pattern.
In FIG. 9B, the second pattern is displaced laterally with respect to the first original pattern, and in FIG. C, the second pattern is displaced obliquely downward to the right with respect to the first original pattern. It is a top view of the state where has occurred.

[Explanation of symbols]

 1 Pattern Exposure Device (Exposure Device) 2 Light Source 3 Half Mirror 4 Exposure Optical Device 5 Reticle Holder 6 Stage 7 X Axis Drive Motor 8 Y Axis Drive Motor 9 Rotation Drive Motor 10 Image Data Input Device 11 Image Data Processing Processor 12 Data processing device 13 Motor drive control device 14 Data input device S Semiconductor wafer ICa 1st original pattern of IC pattern ICb 2nd pattern of IC pattern

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/30 502M

Claims (3)

[Claims] 1. When sequentially exposing and forming a plurality of patterns on an exposed surface of a surface-treated workpiece, the first pattern that has already been exposed and formed is recognized as image data and converted into image data. An exposure method for a pattern, characterized in that the position of the next pattern is aligned while comparing with the image data of the next pattern that has been image-recognized. 2. A first pattern is exposed and formed on an exposed surface of a surface-treated workpiece, the first pattern is subjected to image processing using an image data input device, and a second pattern is superposed. The coordinates of an arbitrary point serving as a reference of are digitized, and the second pattern to be superimposed on the first pattern is subjected to image processing through an exposure optical system to align the first pattern and the second pattern. If it is necessary to further superimpose the Nth pattern on the N−1th pattern thereafter, the image processing is sequentially repeated to form the N−1th pattern already exposed and formed. The alignment with the Nth pattern is performed.
The method for exposing a pattern according to. 3. A stage on which a workpiece to be surface-treated is placed, and a surface to be exposed of the workpiece to be surface-treated is supported so as to be rotatable in the X-axis direction, the Y-axis direction and in a horizontal plane. An X-axis drive motor that drives in the X-axis direction, a Y-axis drive motor that drives the stage in the Y-axis direction, a rotary drive motor that drives the stage in a horizontal plane, and a surface treatment process mounted on the stage An exposure optical device including a light source for sequentially forming N patterns (N is an integer of 1 or more) on an exposed surface of an object, an exposure optical system, and the N sheets formed by the exposure optical device. Image data processing for recognizing the coordinates of an arbitrary point as a reference when the first pattern of the patterns is recognized and the second pattern is superposed on the first pattern. Device, the image data A data processing device that compares the coordinate value of the processing device with the coordinate value of the second pattern, and aligns the first pattern and the second pattern according to the output signal of the data processing device. An exposure apparatus of a pattern, characterized in that it comprises a motor drive control device for controlling the X-axis drive motor, the Y-axis drive motor and / or the rotation drive motor so as to perform.