KR100688726B1 - System and method for photolithography - Google Patents

Abstract

The present invention relates to a photolithography system and method, wherein the disclosed photolithography system includes a track apparatus including an applicator for applying a photoresist to a semiconductor substrate and a developer for developing a substrate, and an exposure apparatus for forming a pattern on the substrate. And a photolithography system comprising an interface by connecting the two devices, the interface measuring the thickness of the photoresist film formed on the substrate transferred to the exposure equipment for exposure after the application in the track equipment is completed. And a thickness measuring device for comparing only the predetermined reference value and transferring only the substrate having a normal thickness of the photoresist film to the exposure apparatus according to the comparison result. The thickness of the photoresist film during the inline process such as photoresist coating, exposure, and development is measured. Number of defects in thickness of photoresist film by real time monitoring By minimizing the process losses due to rework, to reduce the cost of the semiconductor device and improve the productivity, ultimately, there is the advantage of improving the yield.

Photolithography, Spinner, Stepper, Interface, Thickness Measurement

Description

Photolithography System and Method {SYSTEM AND METHOD FOR PHOTOLITHOGRAPHY}

1 is a schematic block diagram of a photolithography system according to the prior art,

2 is a flowchart illustrating a photolithography method according to the prior art;

3 is a schematic block diagram of a photolithography system according to the present invention;

Figure 4 is a block diagram of a thickness measuring device in the photolithography system according to the present invention,

5 is a flow chart for explaining the photolithography method according to the present invention.

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

110: spinner 120: stepper

130: interface 140: thickness measuring device

141: thickness measurement unit 142: control unit

143: alarm unit 144: reject discharge unit

The present invention relates to a photolithography process for semiconductor manufacturing, and more particularly, to a photolithographic system and method for exposing and developing after applying photoresist to a semiconductor wafer.

The photolithography process, which is one of the semiconductor manufacturing processes, is performed in the order of an application process, an alignment and exposure process, a development process, an overlay measurement process, and a critical dimension measurement process. Here, the coding process and the developing process are usually performed by a spinner (also called track equipment), and the alignment and exposure process is usually performed by a stepper or a scanner (also called exposure equipment). The two equipments are usually referred to as in-line equipment because they are connected in-line to perform photolithography processes in sequence, and the application, alignment, exposure and development processes belong to the inline process.

Hereinafter, a photolithography system and a method thereof according to the related art will be described with reference to FIGS. 1 and 2.

The photolithography system according to the prior art has a spinner 10, a stepper 20 and an interface 30 connecting them, as schematically shown in FIG. 1.

When the wafer is loaded on the spinner 10 (S41), the photoresist, which is a material sensitive to light, is evenly applied onto the wafer substrate by the applicator in the spinner 10 (S42).

The wafer on which the photoresist is applied is transferred to the stepper 20 after passing through the interface 30 (S43), and the stepper 20 passes light through a circuit pattern drawn on a mask to form a photoresist film. The circuit pattern is exposed (S44).

After the exposure is completed, the wafer passes through the interface 30 and is then transferred to the spinner 10 (S45), and the developing film in the spinner 10 develops a film of a portion that receives light from the surface of the substrate in an alkaline aqueous solution. (S46).

When the inline process such as coating, exposure, and development is completed as described above, the overlay measuring equipment checks whether any device pattern is correctly aligned. The measurement of the overlay accuracy, i.e., the overlapping accuracy of the semiconductor device, is to check whether the alignment of the device pattern formed by the previous photolithography process and the device pattern formed by the photolithography process currently performed is properly performed. Is compared to the degree of deviation from the previous and current device patterns by emitting onto the aligned wafer and detecting the reflected light beam reflected from the wafer (S47).

As a result of the overlay measurement, if it is determined to be normal, the next process such as a critical dimension measurement process is performed (S49). If it is determined to be abnormal, the photoresist is stripped (S48), and then inline processes such as photoresist coating, exposure and development are performed again. .

On the other hand, in the recent semiconductor manufacturing process, as the degree of integration of semiconductor devices increases, thinning, multilayering, and pattern miniaturization of the films used in the manufacturing process are being promoted, so that film thickness control and structural defects have a great influence on product characteristics.

In particular, the thickness of the photoresist plays a very important role in semiconductor manufacturing. If the thickness is lower than the target, the substrate is over-etched to impact the lower layer. If the thickness is higher than the target, the substrate is under-etched to obtain the desired pattern. Therefore, the process of measuring the thickness of the photoresist film must be accompanied essentially.

However, according to the prior art, after performing all the photolithography process as described above, the thickness measurement process was performed using a separate thickness measuring equipment.

As such, due to the absence of real-time monitoring, the rework rate of re-inline process after stripping due to the poor thickness of the photoresist film is increased, thereby increasing the cost of the semiconductor device and lowering the productivity and lowering the yield. There was this.

The present invention has been proposed to solve such a conventional problem, the process loss by the rework performed when the thickness of the photoresist film is poor by monitoring the thickness of the photoresist film in real time during the in-line process such as photoresist coating, exposure, development, etc. By minimizing this, the purpose is to reduce the cost of the semiconductor device, improve the productivity and ultimately improve the yield.

As one aspect of the present invention for achieving the above object, a photolithography system includes a track device including an applicator for applying a photosensitive liquid to a semiconductor substrate and a developing device for developing a substrate, and an exposure apparatus for forming a pattern on the substrate. And a photolithography system comprising an interface by connecting the two devices, the interface measuring the thickness of the photoresist film formed on the substrate transferred to the exposure equipment for exposure after the application in the track equipment is completed. And a thickness measuring device for comparing only the preset reference value and allowing only the substrate having a normal thickness of the photosensitive film to be transferred to the exposure apparatus according to the comparison result.

According to another aspect of the present invention, a photolithography method is a photolithography method in which a photoresist is applied to a semiconductor substrate in a track equipment and is developed in a track equipment after exposure in an exposure apparatus, the method comprising applying a photoresist onto a semiconductor substrate in a track equipment. And measuring the thickness of the photoresist film formed on the substrate, comparing the measured thickness value with a predetermined reference value, and transferring only the normal semiconductor substrate to the exposure equipment according to the comparison result, and using the exposure equipment on the substrate transferred from the track equipment. Exposing the circuit pattern, and developing the track pattern on the exposed substrate.

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

Figure 3 is a schematic block diagram of a photolithography system according to the present invention, Figure 4 is a block diagram of a thickness measuring device in the photolithography system according to the present invention.

As described above, the photolithography system of the present invention includes a spinner 110, which is a track device for applying a photoresist or developer to a wafer, a stepper 120, which is an exposure device for forming a pattern on a wafer, and a connection therebetween. It has an interface 130.

The spinner 110 includes a port 111 on which a substrate is loaded and unloaded, a spin coater (SCW) 112 for applying a photoresist to the substrate, and a spin developer (SDW) for developing a substrate. 113), a bake unit (BAKE) 114 for heating the substrate, and units such as a wide expose edge wafer (WEEW) 115 for exposing unnecessary photoresist to the circumferential portion of the substrate. It is arranged in a row in line with the flow of.

And, such units are arranged divided on both sides of the central passage. In the passage, one robot 116 is used as a carrier to transfer the substrate, and the robot 116 transfers the substrate to the port 111, the interface unit 130, or each processing unit.

The interface 130 is a port through which the substrate enters and exits from the stepper 120. The interface 130 includes a buffer 132 for waiting to stack wafers provided on the stepper 120 side, and a transfer device 134 for selectively moving the wafers in the buffer 132 to the spinner 110 and the stepper 120. Equipped with.

The thickness measuring device 140 is connected to the interface 130. The thickness measuring device 140 is a non-destructive thickness measuring device such as an ellipsometer or spectrometer. The thickness of the photoresist film formed on the wafer transferred to the stepper 120 for exposure after the coating is completed in the spinner 110 is performed. The measured wafer is compared with the preset reference value, and the normal wafer is transferred to the stepper 120 according to the comparison result, and the abnormal wafer is separated and discharged into the reject cassette.

As shown in FIG. 4, the thickness measuring device 140 includes a thickness measuring unit 141 and a thickness measuring unit 141 which measure the thickness of the photoresist film formed on the wafer in a non-destructive manner using ultrasonic waves or the like. The controller 142 which compares the thickness value with a preset reference value and outputs a normal or abnormal control signal according to the comparison result, and an alarm unit 143 that displays the abnormal thickness state to the outside based on the abnormal control signal of the controller 142. And a reject discharge unit 144 separating and discharging the abnormal wafer through the reject port based on the abnormal control signal of the controller 142.

The normal or abnormal control signal of the control unit 142 is transmitted to the photolithography control unit 1 that controls all processes by the photolithography system, and the photolithography control unit 1 transfers the wafers based on the normal control signal. The control unit 134 controls the transfer to the stepper 120, and the abnormal control signal is recognized as a process standby signal to control the photolithography process to the standby state.

An inline process such as coating, exposure, and development by the photolithography system according to the present invention configured as described above will be described in detail below with reference to FIGS. 3 to 5.

First, when the wafer is loaded on the spinner 110 (S201), the photoresist, which is a light sensitive material, is evenly applied onto the wafer substrate by the applicator 112 in the spinner 110 (S202).

After the application of the photoresist is completed, the wafer enters the interface 130, and the thickness measuring device 140 of the interface 130 measures the thickness of the photoresist film formed on the wafer (S203). The reference value is compared and the normal wafer is transferred to the stepper 120 according to the comparison result (S211), and the abnormal wafer is separated and discharged through the reject port.

Referring to the operation of the thickness measuring device 140 as described above, the thickness measuring unit 141 measures the thickness of the photoresist film formed on the wafer using ultrasonic waves or the like in a non-destructive manner and provides the measured thickness value to the control unit 142. The controller 142 compares the measured thickness value with a preset reference value and determines whether it is normal or abnormal according to the comparison result. If the thickness of the photoresist film is higher or lower than the reference value, the under etching or over etching occurs in the subsequent etching process, and in this case, the controller 142 outputs an abnormal control signal.

Then, the photolithography control unit 1 that controls all processes by the photolithography system recognizes the abnormal control signal of the control unit 142 as the process standby signal and controls the photolithography process to the standby state (S222). In response to the abnormal control signal of the controller 142, the alarm unit 143 displays the abnormal thickness state of the photoresist film to the outside through an alarm lamp or an alarm sound (S223). In addition, the reject discharge unit 144 separates and discharges the abnormal wafer through the reject port based on the abnormal control signal of the controller 142 (S224). The rejected wafer is then subjected to an inline process such as photoresist coating, exposure and development after stripping the photoresist (S231).

When the normal wafer is transferred in step S211, the stepper 120 passes light through the circuit pattern drawn on the mask to expose the circuit pattern on the substrate on which the photoresist film is formed (S212).

After the exposure is completed, the wafer passes through the interface 130 and is then transferred to the spinner 110 (S213), and the film of the light-received portion of the substrate 113 is developed with an aqueous alkali solution in the developer 113 in the spinner 110. (S214).

When the inline process such as coating, exposure, and development is completed as described above, the overlay measuring equipment checks whether any device pattern is correctly aligned. The measurement of the overlay accuracy, i.e., the overlapping accuracy of the semiconductor device, is to check whether the alignment of the device pattern formed by the previous photolithography process and the device pattern formed by the photolithography process currently performed is properly performed. The degree of deviation from the previous and the current device pattern is compared by radiating on the aligned wafer and detecting the reflected light beam reflected from the wafer (S215).

As a result of the overlay measurement, if it is determined to be normal, the next process such as a critical dimension measurement process is performed (S241). If it is determined to be abnormal, the photoresist is stripped (S231), and then inline processes such as photoresist coating, exposure and development are performed again. .

In the detailed description thus far, only the embodiments of the present invention have been described, but it is apparent that the technology of the present invention can be easily modified by those skilled in the art within the scope of the technical idea described in the claims below.

As described above, the present invention monitors the thickness of the photoresist film in real-time during inline processes such as photoresist coating, exposure, and development, thereby minimizing the process loss due to rework performed when the thickness of the photoresist film is poor. This reduces the cost, improves productivity and ultimately improves yield.

Claims (8)

A photolithography system including a track device including an applicator for applying a photoresist to a semiconductor substrate and a developer for developing the substrate, an exposure device for forming a pattern on the substrate, and an interface by connecting the two devices. As The interface is, After the coating is completed in the track equipment, the thickness of the photoresist film formed on the substrate transferred to the exposure equipment for exposure is measured, and the thickness of the photoresist film is increased according to the comparison result by comparing the measured thickness value with a preset reference value. Thickness measuring device that allows only the normal substrate to be transferred to the exposure equipment Including; The thickness measuring device may include a thickness measuring unit which measures the thickness of the photosensitive film formed on the substrate in a non-destructive manner, compares the thickness value measured by the thickness measuring unit with a preset reference value, and according to the comparison result, a normal or abnormal control signal. And a reject discharge unit for separating and discharging the abnormal semiconductor substrate through the reject port based on the abnormal control signal of the controller. Photolithography system comprising a. The method of claim 1, The thickness measuring device is an alarm unit for displaying an abnormal thickness state to the outside based on the abnormal control signal of the control unit. Photolithography system further comprising. delete The method of claim 1, The photolithography system, a photolithography control unit for controlling all processes by the photolithography system More, The photolithography control unit recognizes the abnormal control signal as a process standby signal and controls the photolithography process to a standby state. Photolithography system characterized by. A photolithography method in which a photoresist is applied to a semiconductor substrate in a track device, exposed in an exposure device via an interface, and then developed in the track device via the interface. Coating the photoresist on the semiconductor substrate in the track equipment and entering the interface; Measuring a thickness of the photoresist film formed on the semiconductor substrate at the interface, comparing the measured thickness value with a predetermined reference value and determining a normal semiconductor substrate and an abnormal semiconductor substrate according to the comparison result; Separating and discharging the abnormal semiconductor substrate through the reject port of the interface; Transferring the normal semiconductor substrate to the exposure apparatus; Exposing a circuit pattern in the exposure apparatus on the normal semiconductor substrate transferred from the track apparatus; Transferring the developed normal semiconductor substrate to the track equipment through the interface and developing the exposed semiconductor substrate; Photolithography method comprising a. The method of claim 5, The photolithography method includes comparing the measured thickness value with a predetermined reference value and displaying an abnormal thickness state according to the comparison result. Photolithography method comprising more. delete The method of claim 5, The photolithography method may include controlling the photolithography process to a standby state when comparing the measured thickness value with a predetermined reference value and determining the abnormal semiconductor substrate according to the comparison result. Photolithography method characterized in that.

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