KR100254279B1 - Apparatus and method for reticle alignment - Google Patents

Abstract

PURPOSE: A method for arranging the reticle and its apparatus are provided, to improve the precision of arrangement and the productivity by using a plurality of reticles. CONSTITUTION: The method comprises the steps of driving the reticle stage having a plurality of reticles and moving it to the coordinate for sensing the first arrangement mark, to allow the light from the light source to pass the first arrangement mark formed on a reticle through and to be collected a photosensor; measuring the coordinate of the first arrangement mark from the moved distance of the reticle stage which is measured by using an encoder connected with the reticle stage driving part; driving the reticle stage and moving it to the coordinate for sensing the second arrangement mark, to allow the light from the light source to pass the second arrangement mark formed on a reticle through and to be collected a photosensor; measuring the coordinate of the second arrangement mark from the moved distance of the reticle stage which is measured by using an encoder connected with the reticle stage driving part; and calculating the calibration amount of the reticles from the coordinates of the first and second arrangement marks and storing it.

Description

Reticle alignment method and device

The present invention relates to a reticle alignment method and apparatus, and more particularly, to a reticle alignment apparatus and method for positioning a reticle mounted on the reticle stage in the exposure process.

In general, a reticle is located between a semiconductor chip and a light source, and is used as a photomask for printing a circuit on the semiconductor chip in photolithography. This glass reticle is easily cracked by fine scratches, so it requires careful attention.

An exposure process for exposing an image of a reticle to a liquid crystal plate or a wafer surface includes a loading process in which a reticle is placed on a reticle stage. In the exposure process, it is important to accurately place the reticle at a predetermined position on the reticle stage so that the reticle position error can be corrected by moving the reticle stage.

Therefore, in order to proceed with the loading process of placing the reticle at a predetermined position on the stage, it is necessary to lower the reticle to the reticle stage to reduce the gap to the minimum and to adjust the position while rotating, moving back, front, left, and right. Just keep in mind that too narrow the distance between them, as the reticle will hit the stage and cause scratches.

Conventionally, after detecting the alignment mark formed on the reticle, the relative mark is confirmed by moving the reference mark on the reticle stage under the microscope to set the position of the reticle alignment microscope. The microscope then retrieves the alignment marks of the reticle.

This conventional method is limited to exposure using one reticle, and this one reticle is disadvantageous in many respects. For example, several types of reticles are used to expose a large LCD plate, and each reticle must be moved one on the reticle stage according to the above process. As a result, a large amount of time is consumed when the reticle is replaced, thereby decreasing productivity in the exposure process.

Accordingly, an object of the present invention is to provide a reticle alignment method and apparatus for inventing an exposure process more quickly and accurately.

In order to achieve the above object, the reticle alignment method according to an aspect of the present invention, the reticle stage is a plurality of reticle seated so that the light emitted from the light source passes through the first alignment mark formed on any reticle is received by the optical sensor Driving to move to the coordinate where the first alignment mark is sensed; Measuring coordinates of the first alignment mark through a moving distance of the reticle stage measured from an encoder connected to the reticle stage driver; Driving the reticle stage so that the light emitted from the light source passes through the second alignment mark formed on the reticle and is received by an optical sensor to move to the coordinate where the second alignment mark is sensed; Measuring coordinates of the second alignment mark through a moving distance of the reticle stage measured from the encoder connected to the reticle stage driver; Calculating and storing the position correction value of each reticle from the measured coordinates of the first and second alignment marks.

In addition, according to another aspect of the invention, the light emitted from the light source to project the reticle stage capable of seating a plurality of reticles, and at least two alignment marks formed on the reticle, respectively by the optical path through the optical sensor At least one optical system, an interface for detecting or processing a signal generated by the optical sensor, a reticle stage driver for driving the reticle stage in X, Y, and θ directions, a controller for controlling the reticle stage driver, and the reticle Reticle alignment including an encoder for receiving a signal from the stage driver to measure the distance traveled by the reticle stage, a central processing unit for receiving and processing the signal from the interface and the encoder, and sends a control signal to the reticle stage control unit An apparatus is provided.

1 is a perspective view showing a reticle alignment device and a loading device for supplying a reticle to the alignment device according to the present invention.

Figure 2 is a block diagram showing a reticle alignment device according to the present invention.

3 is a flowchart illustrating a method of aligning a reticle according to the present invention.

<Description of the symbols for the main parts of the drawings>

10 ... Reticle Cabinet 11 ... Reticle

12 ... alignment mark 20 ... carrier

21 ... Fork 22 ... 4 Link

30 ... Reticle Stage 31 ... Air Hole

40 ... reticle loading device 41 ... light source

42 First lens 43 Reflector mirror

44 ... second lens 45 ... sensor

47 Interface 48 Central Processing Unit

49 ... Reticle stage control unit 50 ... Reticle stage drive unit

51.Encoder

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view showing a reticle alignment device and a loading device for supplying a reticle to the alignment device according to the present invention. As shown, the reticle loading device 40 loads the reticle 11 stored in the reticle cabinet 10 at a predetermined position of the reticle stage 30 using the fork 21 of the reticle carrier 20. At this time, the reticle loading device 40 is preferably mounted on the reticle stage 30 with the error range as small as possible. The fork 21 of the reticle carrier 20 is lowered with a minute spacing to seat the reticle 11 on the reticle stage 30. At this time, compressed air is blown out from the air hole 31 installed in the reticle stage 30, and a four-section link 22 is installed between the fork 21 and the body of the carrier 20 so that the reticle 11 is staged. It can be kept parallel to the 30, it is possible to prevent the reticle 11 and the stage 30 hit the scratches. This reticle loading process may be referred to as a pre alignment process of the reticle.

1 and 2, the reticle alignment device 50 according to the present invention includes a reticle stage 30 and an optical system. The reticle stage 30 is driven in the X, Y, and X, Y, and θ directions, respectively, by the reticle stage driving pupil 50, and the reticle driver 50 is controlled by the reticle stage controller 49. do. The reticle stage driver 50 is connected to the encoder 51 so that the distance that the reticle stage is moved by the reticle stage driver 50 is measured by the encoder 51. Here, the reticle stage 30 is provided with a receiving portion that can seat a plurality of for example four reticles as shown.

The optical system includes a light source 41, an alignment mark 12 formed on the reticle to allow light from the light source 41 to pass therethrough, and light that receives or passes through the alignment mark 12 from the light source 41. Sensor 45. That is, the optical sensor 45 detects the alignment mark 12 formed on the reticle. In order to change the path of the light emitted from the light source 41, the first lens 42 collecting light at a predetermined position on the mirror 39 is preferably provided. The lens 42 and the mirror 39 are preferably located between the light source 41 and the alignment mark 12. The second lens 44 and the reflecting mirror 43 for receiving the light passing through the alignment mark 12 are preferably located between the alignment mark 12 and the sensor 45.

The interface 47 receives a signal generated by the optical sensor 45, processes the signal, and transmits the signal to the central processing unit 48.

The central processing unit 48 also receives and processes the signal received from the encoder 51 and sends a control signal to the reticle stage control unit 49. Therefore, the central processing unit 48 transmits a signal to the reticle stage control unit 49 to drive and move the reticle stage 30, while the encoder 51 when the alignment mark 12 is detected by the optical sensor 45. Enter the value of. The measured value input from this encoder 51 is compared with the exact reference value of the preset reticle, and the value which the said reticle deviated from the correct position is calculated. In this way, by comparing the measured and reference values for at least two alignment marks 12, it is possible to determine the degree of deviation from the position for a particular reticle. That is, since two reference value coordinate values are stored in advance for the reticle, and two coordinate values measured from the encoder 51 are inputted, and when the reference value and the measured value are processed, the corresponding reticle is separated from the reference value coordinate value. As the accuracy, X, Y, and θ values, which are position correction values in the rotation direction θ on the X, Y, and XY planes, can be calculated. The result of the position correction value thus obtained is stored in the memory. The corrections for each stored reticle are used as data to move the reticle stage to align each individual reticle so that the exposure process is performed at the correct location for that reticle.

3 is a flowchart illustrating a method of aligning a reticle according to another embodiment of the present invention.

Since a plurality of reticles may be simultaneously seated in the reticle stage, the variable i is first set to 1 to perform the reticle alignment method for the first reticle (300).

In order to determine whether the position of one reticle is an appropriate position, the coordinates of at least two alignment marks, that is, the first alignment mark and the second alignment mark, should be measured. In order to measure the coordinates of each alignment mark, the first alignment mark formed on the reticle is first moved to the sensing coordinates. That is, the reticle stage is driven and moved so that the light emitted from the light source passes through the first alignment mark formed on the predetermined reticle and is at a position where the light sensor receives the light. When the first alignment mark is detected by the optical sensor, the value of the encoder at that time may be input to measure the coordinate value of the first alignment mark (320).

In the same manner, the second alignment mark is moved to the sensing coordinate (334), and the coordinate value of the second alignment mark at that time is measured (340).

When the coordinates of the first and second alignment marks are measured with respect to one reticle [i], the position correction values X, Y, and θ of the reticle may be calculated from the reference point, and the result may be stored (350).

It is determined whether all of the reticles seated in the reticle stage have obtained the above-described position correction values (360). If not obtained for all reticles, increase the variable i by one (370) and repeat the above procedure until returning to step 310 to obtain position corrections for all reticles.

When the position correction values are obtained for all the reticles by the above-described method, since the position correction values of each reticle are stored in the memory, these values are used in the exposure process. That is, when each reticle is used in the exposure process, the reticle stage driving unit is driven according to the position correction value of the corresponding reticle so that the exposure process is performed while the corresponding reticle is correctly set at the reference position. When the exposure process is completed for one reticle, the exposure process is restored to its original state, and the exposure process is performed by performing position correction on the reticles of the next order according to the correction values of the corresponding reticle.

Therefore, in order to perform the exposure process for each reticle, the variable i is first set to 1 (400). Thereafter, the position correction value [i] of each reticle stored by the method described above is read (410). The reticle stage is moved according to the read position correction value [i] (420), and the exposure process is performed after the corresponding reticle is correctly aligned (430). The above-described alignment and exposure process is repeatedly performed for the entire reticle (450).

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments. Dimensions, shapes, relative arrangements, etc. of components described in this embodiment are not intended to limit the scope of the present invention only to them unless specifically stated, and are merely illustrative examples. And various modifications and improvements within the range are possible.

As described above, the reticle alignment method and apparatus according to the present invention can perform accurate exposure alignment in performing a batch exposure process using a plurality of reticles, so that high-precision exposure can be efficiently performed. Contributes greatly to improvement.

Claims (3)

Driving a reticle stage on which a plurality of reticles are seated so that light emitted from the light source passes through a first alignment mark formed on an arbitrary reticle and is received by an optical sensor; Measuring coordinates of the first alignment mark through a moving distance of the reticle stage measured from an encoder connected to the reticle stage driver; Driving the reticle stage so that the light emitted from the light source passes through the second alignment mark formed on the reticle and is received by an optical sensor to move to the coordinate where the second alignment mark is sensed; Measuring coordinates of the second alignment mark through a moving distance of the reticle stage measured from the encoder connected to the reticle stage driver; And calculating and storing a position correction value of each reticle from the measured coordinates of the first and second alignment marks. The method of claim 1, Reading the position correction value of the corresponding reticle; And moving the reticle stage according to the read position correction value. A reticle stage that can seat multiple reticles, At least one optical system for receiving light emitted from a light source by an optical sensor through an optical path so as to project at least two alignment marks formed on the reticle, respectively; An interface for detecting or processing a signal generated by the optical sensor; A reticle stage driver for driving the reticle stage in the X, Y, and θ directions; A controller for controlling the reticle stage driver; An encoder which receives a signal from the reticle stage driver and measures a distance traveled by the reticle stage; And a central processing unit for receiving a signal from the interface and the encoder, processing the signal, and sending a control signal to the reticle stage controller.