KR100387763B1 - Enhanced exposer and method for leveling wafer in the exposer - Google Patents

Abstract

The present invention relates to an exposure apparatus of a semiconductor device and a method of adjusting the tilt in the exposure apparatus, further comprising a parallel flat glass on the light transmitting side for performing both focusing and tilting control, according to the angle change of the parallel flat glass. When the amount of reflected light reflected at each detection point is photoelectrically converted by the sensor and detected as an electrical signal, the inclination is calculated based on the detected amount, and based on the calculated inclination, the wafer stage is driven to adjust the inclination of the wafer. By simplifying the optical system of the equipment, it is easy to design the exposure equipment, it is possible to reduce the manufacturing cost. In addition, the present invention, by using such an exposure equipment, when the focus adjustment is completed, in a state in which the stage on which the wafer is mounted is fixed, the position of the light incident on the wafer with the parallel plate glass is sequentially changed to take one shot of the wafer. By detecting the reflected light from four detection points located therein, and adjusting the inclination of the wafer by the detected reflected light, the accuracy of the inclination adjustment is improved by excluding errors due to the wafer stage movement.

Description

Improved exposure equipment and method of adjusting wafer inclination in the exposure equipment {ENHANCED EXPOSER AND METHOD FOR LEVELING WAFER IN THE EXPOSER}

The present invention relates to an exposure apparatus used in semiconductor manufacturing and a wafer tilt adjustment method in the apparatus, and more particularly, to an exposure apparatus improved from an existing focusing apparatus to perform tilt adjustment as well as focus adjustment. A tilt control method in exposure equipment.

As is well known, photolithography techniques are used in the manufacturing process of semiconductor devices to define the shape of each layer of the semiconductor device formed on a silicon substrate. That is, after the photosensitive film is formed on the target layer to define the shape, the light formed from the light source passes through the reticle having the predetermined shape and is irradiated to the photosensitive film to transfer the shape formed on the reticle to the photosensitive film ( Exposure step), by removing only the shape portion (or non-transferred shape portion) transferred to the photosensitive film with the developing solution (developing step), and then removing the target layer exposed due to the development of the photosensitive film by etching (etching step). The target layer is defined in a desired shape.

In such a photolithography process, one of the processes which has a big influence on the exact pattern shape is an exposure process. That is, the position where the pattern is formed, the size of the pattern, etc. are greatly changed by the focus adjustment, the tilt adjustment, the alignment and the like.

In view of such points, conventional exposure equipment includes a reduction projection lens for irradiating light to a wafer, an auto focusing system for placing the wafer at a focus of light irradiated from the reduction projection lens, and a reduction projection. A plurality of optical systems such as an auto leveling system for orthogonalizing the wafer in the optical path irradiated from the lens is provided.

First, referring to FIG. 1, in the optical system of the focusing apparatus provided in the conventional exposure apparatus, a light transmitting side is disposed on one side and a light receiving side is disposed on the other side with respect to the projection lens 110. Here, the light transmitting side is composed of a light transmitting slit 120 and a light transmitting side mirror 130, and the light receiving side is a light receiving side mirror 150, an oscillator 160, a focus shift halving 170, and a light receiving slit ( 180). In this arrangement, the focusing light irradiated from the light source is irradiated onto the light transmitting side mirror 130 through the light transmitting slit 120, reflected from the light transmitting side mirror 130, and placed on the stage 140 at a predetermined angle. The mounted wafer is irradiated. The light for focusing incident on the wafer is reflected on the surface of the wafer and irradiated to the light receiving side mirror 150, and then reflected from the light receiving side mirror 150 and vibrated by the vibrator 160 while receiving the light receiving slit 180. Is imaged on. As such, the amount of change of light passing through the light receiving slit 180 is photoelectrically converted into a sensor (not shown) to perform focus adjustment.

On the other hand, referring to Figure 2, the optical system of the tilt control device provided in the conventional exposure equipment is composed of an optical system separate from the above-described focusing device optical system, the light receiving side on the light collecting lens 220 and the position detector 210 ) Is provided. Similar to the light-transmitting side of the optical system for focusing apparatus described above, the light irradiated onto the wafer 230 at a predetermined angle is reflected on the surface of the wafer 230, and then focused on a spot by a condenser lens, and then a position detector 210 is irradiated. At this time, the position detector 210 is composed of a four-segmented sensor, the light is converted into electricity in each sensor, and then driving the stage in a direction in which the two electric quantities summed together by the electric quantities detected by the sensors located in the diagonal direction to each other To adjust the inclination of the wafer. That is, if the reflected light deviates from the center of the position detector 210 due to the inclination of the wafer (or pattern on the wafer) mounted on the stage as shown in FIG. 2A, the reflected light is described above until it is located at the center of the position detector 210. The position of the wafer 230 is adjusted by the method. As a result, the inclination of the wafer 230 is adjusted as shown in FIG. 2B.

Conventional exposure equipment performs the focus adjustment and the tilt adjustment by the above-described configuration, but the optical system for the focus adjustment and the tilt adjustment optical system is provided separately, there is a problem that the optical system is complicated.

In addition, conventionally, since focus adjustment is performed by moving a stage on which a wafer is mounted, there is an incorrect problem due to an error caused by mechanical movement or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object thereof is to provide an exposure apparatus and an accurate tilt control method with a simple configuration of an optical system.

In order to achieve the above object, in one aspect of the present invention, the light transmitting side for irradiating light to the wafer mounted on the stage, the light receiving side for receiving the reflected light reflected from the wafer, and the amount of change of the light detected at the light receiving side. An exposure apparatus having a focusing device for arranging the wafer in a focus range of exposure light irradiated from a main light source, wherein the exposure apparatus further comprises a parallel flat glass on the transmitting side for performing both the focusing and the tilting. When the amount of reflected light reflected at each detection point according to the angle change of the parallel plate glass is photoelectrically converted by the sensor and detected as an electrical signal, the slope is calculated based on the detected amount, and based on the calculated slope, The inclination of the wafer is adjusted by driving the wafer stage.

In order to achieve the above object, in another aspect of the present invention, in a method for adjusting the inclination of the wafer in the exposure equipment further provided with a parallel plate glass for changing the position of the light on the transmitting side of the focusing device, the focus When the focus adjustment is completed in the adjusting device, the position of the light irradiated from the focus control light source is changed by changing the angle of the parallel flat glass while the wafer is fixed, and the four detection points A, B, Measuring the amount of reflected light at each of the four detection points while sequentially changing to C and D), the first addition value obtained by adding the amount of light detected at the detection points A and C located in the diagonal directions to each other and the diagonal direction to each other. Calculating a second addition value obtained by adding the amounts of light detected at the detection points B and D located at, and dividing the difference between the first addition value and the second addition value by two; Calculating a slope of the tapered and moving the wafer by the tilt in the direction corresponding to the direction code of the calculated slope will be characterized by including the step of adjusting the tilt of the wafer.

1 is a view showing a focusing apparatus of a general exposure equipment,

2 is a view illustrating a method for adjusting the inclination of a wafer according to the prior art;

3 is a block diagram showing a focusing device modified according to the present invention;

Figure 4 is a flow chart illustrating a wafer tilt adjustment method according to the present invention.

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

110: projection lens 120: light transmitting slit

130: light transmitting side mirror 140: stage

150: light receiving side mirror 160: vibrator

170, 310: parallel plate glass 180: light receiving slit

210: position detector 220: condensing lens

230: Wafer

Referring to Figures 3 and 4, the preferred embodiment of the present invention will be described in more detail as follows.

3 is a block diagram illustrating a focus control apparatus modified according to the present invention, and FIG. 4 is a flowchart illustrating a wafer tilt adjusting method according to the present invention.

First, referring to FIG. 3, the exposure apparatus according to the present invention further installs a parallel plate glass 310 for changing the position of light on the transmitting side of the conventional optical focusing apparatus for replacing the conventional optical tilt adjusting system. It is configured to Since the optical system for the focusing device of the exposure apparatus has been described above, a description thereof will be omitted. Hereinafter, the configuration and function of the parallel plate glass 310 added according to the present invention will be described in more detail. same.

The parallel plate glass 310 is disposed between the light transmitting slit 120 and the light transmitting side mirror 130 to change the position of the light incident from the light source to the light transmitting side mirror 130 through the light transmitting slit 120, that is, the light path. do. In order to change the light path as such, the parallel plate glass 310 will have to be disposed on the optical axis of the light passing through the transmission slit 120. In addition, the drive device which is not shown in figure may be connected to the parallel flat plate glass 310. That is, the driving device of the parallel plate glass 310 is generally used in an optical system, and thus, a detailed illustration thereof is omitted, but basically includes a driving motor and a control unit for moving the parallel plate glass 310. Driving amount of the parallel plate glass 310 with the driving amount-for example, the driving amount for moving to the four detection points for detecting the reflected light to replace the existing position detector in the present invention, or based on the operator's operation The angle of the parallel plate glass 310 is changed by driving the parallel plate glass 310 by a driving amount. As a result, the optical path incident on the transmitting side mirror 130 through the transmitting slit 120 will be changed, and thus the optical path reflected on the transmitting side mirror 130 and incident on the wafer 230 will also be changed. At this time, it is preferable that the four detection points are four points within one shot of each of the extension lines of the vertices located in the diagonal direction, and the distances from the orthogonal points are the same, for example, four of the one shot of the wafer. It could be a vertex.

Hereinafter, referring to FIG. 4, the process of implementing the inclination adjustment method according to the present invention in the above-described exposure apparatus will be described.

First, when the focus adjustment is completed (S10), the control device (not shown) fixes the stage 140 on which the wafer is mounted (S20).

In such a state that the stage 140 is fixed, the parallel plate glass 310 is changed to an angle corresponding to the predetermined detection point A by the control device (not shown) (S 30). As a result, the optical path incident on the light transmitting side mirror 130 through the light transmitting slit 120 is changed, and the reflected light reflected from the light transmitting side mirror 130 again is a predetermined detection point of one shot of the wafer mounted on the stage 140. It enters into (A). The incident light is reflected at the detection point A, incident on the light receiving side mirror 150, and then vibrated by the vibrator 160 to form an image on the light receiving slit 180.

As such, according to the angle change of the parallel plate glass 310, the amount of reflected light reflected at the detection point A is photoelectrically converted by a sensor (not shown) and detected as an electrical signal (for example, a voltage) (S 40). ).

When the reflected light at the detection point A is detected as described above, the above-described steps S30 and S40 are repeated until the detection of all the detection points A, B, C, and D is completed (S50). , The reflected light at the detection points A, B, C, and D is detected.

After detecting the amount of reflected light at each of the detection points A, B, C, and D, the inclination of the wafer is calculated based on the detected amount (S60). That is, the first addition value is calculated by adding the detection amounts at the detection points A and C, and the second addition value is calculated by adding the detection amounts at the detection points B and D. Then, the inclination of the wafer is calculated by the formula of "(first addition value-second addition value) / 2". At this time, in the equation, the first addition value and the second addition value may be applied interchangeably, and the sign of the calculated inclination will mean the direction, and the inclination means the inclination amount.

Thereafter, the inclination of the wafer is adjusted by driving the wafer stage based on the inclination calculated in the above-described step S60 (S70).

According to the present invention described above, the configuration of the optical system is simplified, the design of the exposure equipment is easy and the manufacturing cost is reduced, and the effect of eliminating the errors caused by the wafer stage movement to increase the accuracy of the tilt adjustment.

Claims (3)

The wafer is placed in the focal range of the exposure light irradiated from the main light source by using the transmitting side for irradiating light to the wafer mounted on the stage, the receiving side for receiving the reflected light reflected from the wafer, and the amount of change of the light detected at the receiving side. In the exposure apparatus provided with the focusing apparatus for arranging, A parallel plate glass is further provided on the light transmitting side to perform both the focusing and the tilting, and the amount of reflected light reflected at each detection point according to the angle change of the parallel plate glass is photoelectrically converted by the sensor and converted into an electrical signal. And if detected, calculate the inclination based on the detected amount, and adjust the inclination of the wafer by driving the wafer stage based on the calculated inclination. In the method of adjusting the inclination of the wafer in the exposure equipment further provided with a parallel plate glass for changing the position of the light on the transmitting side of the focusing device, When focusing is completed in the focusing device, the position of the light irradiated from the focusing light source is changed by changing the angle of the parallel flat glass in the state where the wafer is fixed. Measuring the amount of reflected light at each of the four detection points while sequentially changing to B, C, and D); Calculating a first addition value obtained by adding the amounts of light detected at the detection points A and C located in the diagonal directions to each other and a second addition value obtained by adding the amounts of light detected at the detection points B and D located in the diagonal directions with each other; Calculating the inclination of the wafer by dividing the difference between the first addition value and the second addition value by two; And adjusting the inclination of the wafer by moving the wafer by the inclination in a direction corresponding to the sign direction of the calculated inclination. The method of claim 2, The four detection spots A, B, C, and D are orthogonal to each other, and the extension lines of the vertices in the diagonal direction are perpendicular to each other, and the distances from the orthogonal points are four points in one shot of the same wafer, respectively. Wafer tilt adjustment method.