KR20070080165A - Flatness sensor apparatus of wafer stage and method for sensing thereof - Google Patents

Abstract

A flatness detecting apparatus of a wafer stage and a method thereof are provided to check the existence of particles in short time and to detect a damaged portion of a surface of the wafer stage by using a sensor unit. A flatness detecting apparatus includes a wafer stage(106) for loading a wafer, a sensor unit, and a control unit. The sensor unit(104) irradiates a laser beam onto a surface of the wafer stage and obtaining detection data from the laser beam reflected from the surface of the wafer stage. The control unit(102) receives the detection data from the sensor unit and discriminates the flatness of the surface of the wafer stage. The sensor unit obtains the detection data by checking the time difference between a laser beam irradiation point and a laser beam reflection point.

Description

Flatness detection device of wafer stage and its method {FLATNESS SENSOR APPARATUS OF WAFER STAGE AND METHOD FOR SENSING THEREOF}

1 is a view showing the configuration of a flatness sensing device of a wafer stage according to the present invention;

FIG. 2 is a waveform diagram illustrating the sensed data of the sensor unit shown in FIG. 1. FIG.

3 is a sensed data waveform diagram according to an embodiment of the present invention; And

4 is a flowchart illustrating a flatness sensing procedure of the wafer stage according to the present invention.

Explanation of symbols on the main parts of the drawings

100: semiconductor manufacturing equipment

102: control unit

104: sensor unit

106: wafer stage

108: projection lens

110: Particles

The present invention relates to a semiconductor manufacturing facility, and more particularly, to an apparatus and a method for sensing the flatness of a wafer stage to detect whether a wafer stage surface is damaged and whether particles are present.

In general, a semiconductor exposure apparatus that processes a photolithography process in a semiconductor manufacturing process forms a circuit pattern on a semiconductor substrate using an optical system including a photo mask or a reticle, a light source, a lens, and the like. That is, the semiconductor exposure equipment exposes the photoresist coated on the wafer with light scanned from the light source, and forms a desired pattern on the wafer through a developing and etching process.

In such exposure equipment, for example, an exposure process is frequently performed while particles are present on the wafer stage (or chuck) surface on which the wafer is placed. There is a slight height difference in the Z-axis direction between the position and the position where the particle does not exist.

As a result, when the exposure process is performed repeatedly, defects such as poor focus on the wafer exposed by the particles present on the wafer stage surface are caused.

To prevent this, the semiconductor exposure apparatus performs a local cleaning process of the wafer stage, which checks the flatness of the wafer stage using an active wafer to compare data before and after the local cleaning process. That is, after loading the active wafer into the wafer stage (or chuck), the flatness of the wafer stage is inspected. This test method has a problem that it takes a long time.

It is an object of the present invention to provide an apparatus and method for detecting whether a wafer stage surface is damaged in a semiconductor exposure facility.

Another object of the present invention is to provide an apparatus and method for detecting the presence of particles on a wafer stage surface in a semiconductor exposure facility.

To achieve the above objects, the flatness sensing device of the wafer stage is characterized by using a laser. As such, the device may check the surface state of the wafer stage by acquiring detection data on the difference in the time required for irradiation and detection of the laser in response to the surface state of the wafer stage.

The flatness sensing device of the present invention comprises: a wafer stage on which a wafer is placed; A sensor unit for irradiating a laser onto the wafer stage surface while moving in a scanning direction, receiving a laser reflected from the wafer stage surface, and obtaining sensing data; And a controller configured to receive the sensed data from the sensor unit and determine flatness of the wafer stage surface.

In one embodiment, the sensor unit; The detection time is acquired by sensing the time required from the irradiation of the laser to the reflection by the distance from the wafer stage.

In another embodiment, the control unit; The sensed data is used to determine whether the wafer stage surface is damaged or whether particles on the wafer stage surface are present.

According to another feature of the invention, there is provided a processing method of an apparatus for detecting the flatness of a wafer stage. According to this method, the processing method of the flatness sensing apparatus: irradiates a laser from the sensor part to the wafer stage surface. The laser reflected from the wafer stage surface is received by the sensor unit. The time required from the irradiation of the laser to the reflection is sensed. Subsequently, the flatness of the wafer stage surface is determined in response to the detection result.

In one embodiment, the sensing is to detect the time required by the distance difference between the sensor unit and the wafer stage.

In another embodiment, determining the flatness determines whether the wafer stage surface is damaged and whether particles are present on the wafer stage surface.

The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted as being limited by the embodiments described below. These examples are provided to more fully explain the present invention to those skilled in the art. Therefore, the shape of the components in the drawings, etc. have been exaggerated to emphasize a more clear description.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4.

1 is a diagram illustrating a part of a configuration of a semiconductor exposure apparatus according to the present invention.

Referring to FIG. 1, for example, a semiconductor exposure apparatus 100, for example, a scanner apparatus of Canon Corp., may be used to detect flatness of the wafer stage 106 using a laser delay time, that is, a required time (T in FIG. 2). 102 to 106). And components of a typical semiconductor exposure installation, for example, a light source (not shown), an optical system such as projection lens 108, and drive devices (not shown) for scan movement.

The flatness sensing devices 102 to 106 measure the flatness of the wafer stage 106 on which the wafer is loaded, the sensor unit 104 for sensing the flatness of the wafer stage 106, and the sensed flatness of the wafer stage 106. The controller 102 may be configured to determine whether the wafer stage 106 is damaged by the surface of the wafer stage 106 and whether or not the particle 110 is generated. The flatness sensing devices 102 to 106 check the flatness of the wafer stage 106 using a laser.

Specifically, the sensor unit 104 is provided between the wafer stage 106 and the projection lens 108 to irradiate a laser (optical signal) to the surface of the wafer stage 106 while scanning movement in the X-axis direction, and irradiated laser Is reflected by the surface of the wafer stage 106, this reflected laser is received to obtain sensing data (DATA in FIG. 2) for the surface of the wafer stage 106.

The controller 102 receives the sensing data DATA from the sensor unit 104 and determines the flatness of the wafer stage 106 to determine whether the surface of the wafer stage 106 is damaged or whether particles are present.

As illustrated in FIG. 2, the sensed data DATA may indicate that a certain tendency is damaged or particles 110 are present on the surface of the wafer stage 106 at a location (or section) A3 where a change occurs.

That is, the place where the laser does not exist among the sensing data DATA in the first section A1 means a region of a scanning starting position to a portion other than the wafer stage 106, and the value of the reflected laser is Where present means that the sensor unit 104 has entered the position above the wafer stage 106.

Intrinsic height difference T3-T2 of the wafer stage 106, that is, inherent to the wafer stage 106, is detected by the laser having a predetermined delay time in the sensing data DATA of the second section A2. It means the surface shape.

In addition, the sensing data DATA of the third section A3 is an area that greatly deviates from the tendency of the existing sensing data, and a material, that is, particles 110 or different surfaces on the wafer stage 106 is different from the surface of the wafer stage 106. It can be seen that the shape different from the position, for example, is damaged and the time T1 at which the laser is reflected and detected is reduced.

Therefore, the sensing data DATA is as shown in FIG. 3, in relation to the required time T at which the laser irradiated from the sensor unit 104 to the wafer stage 106 is reflected from the surface of the wafer stage 106 (a). By inverting the sensed data DATA (a), the surface state of the actual wafer stage 106 can be confirmed. That is, inversed data b means the state of the wafer stage 106 surface. Thus, comparing the inversed data b with the data c of the surface state of the original wafer stage 106, the detection of a particular trend is due to the different time required for each position of the wafer stage 106. Data 120 and 130 are acquired, where it can be seen that the particle and / or wafer stage 106 surface is damaged.

In addition, the flatness sensing devices 102 to 106 of the present invention use a laser to increase the scanning speed to check the surface state of the wafer stage 106, thereby reducing the time (T) required to confirm the presence or absence of the particle 110. . In addition, in the case of performing a stage flatness check of the wafer stage 106 after cleaning the wafer stage 106, the time required for the flatness inspection is about 45% of the total required time (for example, about 20 to about cleaning). 25 minutes, which takes about 15 minutes of flatness inspection), by reducing the rate, it is possible to reduce the time required due to the local cleaning process, which occurs frequently (for example, about 3 cases per day).

4 is a flowchart illustrating a flatness sensing procedure of the wafer stage according to the present invention.

Referring to FIG. 4, in step S150, the laser is irradiated onto the wafer stage 106 while the sensor unit 104 is scanned in the X axis direction. If the laser irradiated in step S152 is reflected by the surface of the wafer stage 106, it is accepted by the sensor unit 104 to obtain the sensing data DATA for the required time T of the reflected laser.

The difference in the time required for reflection and detection in laser irradiation is determined using the sensing data DATA acquired in step S154. That is, it is determined whether the sensing data DATA of a specific trend is generated at a specific position of the wafer stage 106 and thus the required time T is sensed.

As a result of the determination, if the required time T is reduced, the procedure proceeds to step S156 to check whether the surface of the wafer stage 106 at the corresponding position is damaged or the particles (110 in FIG. 1) are present. Therefore, damage to the surface of the wafer stage 106 is repaired or the wafer stage 106 is cleaned to remove particles.

If the required time T has not been reduced, that is, if the sensed data DATA of a particular tendency is not obtained, the process proceeds to step S158 where the wafer stage 106 surface is good, thus completing the wafer stage 106 surface inspection. And the subsequent process.

As described above, the flatness sensing devices 102 to 106 that inspect the flatness of the wafer stage 106 according to the present invention inspect the flatness of the wafer stage 106 using a laser. In addition, the inspection method detects the reflection of the wavelength of the laser by the sensor unit 104 and the control unit 102 analyzes it for each time required. Therefore, a specific trend in the entire wafer stage 106, that is, the point where the waveform shape of the sensing data DATA according to the surface of the wafer stage 106 differs from the other points, is searched for before and after the presence of the particle 110 and before and after local cleaning. Compare the data. Therefore, not only the time required for the flatness inspection of the wafer stage 106 can be reduced, but also the surface of the wafer stage 106 can be identified.

In the above, the configuration and operation of the wafer stage flatness sensing apparatus according to the present invention has been shown in accordance with the detailed description and drawings, but this is merely described by way of example, and various changes without departing from the technical spirit of the present invention. And changes are possible.

As described above, the semiconductor exposure apparatus of the present invention includes a device for detecting the flatness of the wafer stage by using a laser, thereby measuring the reflection delay time of the laser to obtain sensing data, and Trends can be determined to quickly identify the presence of particles that can cause local focus, as well as basic information such as damage to the surface of the wafer stage.

Claims (6)

In the flatness detection device of the semiconductor exposure equipment: A wafer stage on which the wafer is placed; A sensor unit for irradiating a laser onto the wafer stage surface while moving in a scanning direction, receiving a laser reflected from the wafer stage surface, and obtaining sensing data; And a control unit which receives the sensing data from the sensor unit and determines the flatness of the wafer stage surface. The method of claim 1, The sensor unit; And detecting the time required from the irradiation of the laser to the reflection based on the distance from the wafer stage to obtain the detection data. The method according to claim 1 or 2, The control unit; And detecting the damage of the wafer stage surface and the presence or absence of particles on the wafer stage surface using the sensed data. In the method of processing the flatness detection device: Irradiating a laser from the sensor portion to the wafer stage surface; Receiving the laser reflected from the wafer stage surface into the sensor portion; Sensing the time required from the irradiation of the laser to the reflection; And determining the flatness of the surface of the wafer stage in response to the detection result. The method of claim 4, wherein The detecting may include detecting the time required by a distance difference between the sensor unit and the wafer stage. The method according to claim 4 or 5, The determining of the flatness may include determining whether the wafer stage surface is damaged and whether particles are present on the wafer stage surface.

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