KR20070030429A - High repetition rate laser with multi chamber - Google Patents

Abstract

In a laser system for manufacturing a semiconductor device, the seed light oscillator generates seed light. Optical members disposed on the path of the seed light are sequentially divided into the seed light. A plurality of laser beam oscillators respectively amplify the divided lights to form pulsed laser beams. The optical members are made of an optical retarder material such that the divided lights are provided to the laser beam oscillators at different time differences. Thus, the seed light generated from the seed light oscillator may be dividedly provided to the laser beam oscillators with a time difference by the optical retardation material to generate a pulsed laser beam having a high repetition rate.

Description

Laser system for semiconductor device manufacturing {High repetition rate laser with multi chamber}

1 is a schematic diagram illustrating a conventional laser system.

2 is a schematic diagram illustrating a laser system according to an embodiment of the present invention.

3 is a graph for comparing the intensity and repeatability of a laser beam of the laser system with a conventional laser system.

Explanation of symbols on the main parts of the drawings

100: seed light oscillator 110: first laser beam oscillator

120: second laser beam oscillator 130: third laser beam oscillator

140: fourth laser beam oscillator 112, 122, 132: first to third light splitting mirrors

102, 118, and 142: first to third total mirrors

128, 138, and 148: first to third transflective mirrors

The present invention relates to a laser system for manufacturing a semiconductor device. More particularly, it relates to a laser system for performing a photo lithography process.

In general, a semiconductor device includes a Fab process for forming an electrical circuit on a silicon wafer used as a semiconductor wafer, an electrical die sorting (EDS) process for inspecting electrical characteristics of the semiconductor devices formed in the fab process; Each of the semiconductor devices is manufactured through a package assembly process for encapsulating and individualizing the epoxy resins.

The fab process includes a deposition process for forming a film on a wafer, a chemical mechanical polishing process for planarizing the film, a photolithography process for forming a photoresist pattern on the film, and the photoresist pattern using the photoresist pattern. An etching process for forming the film into a pattern having electrical characteristics, an ion implantation process for implanting specific ions into a predetermined region of the wafer, a cleaning process for removing impurities on the wafer, and a process for forming the film or pattern Inspection process for inspecting the surface;

The photolithography process is a process of forming a pattern as a photoresist to define a portion to be etched or ion implanted and a portion to be protected. To this end, a process of spin coating a photoresist on a wafer, an exposure process of aligning the photoresist and a mask, selectively irradiating light through the mask, and a process of developing the photoresist are sequentially performed.

'Light' is the most important factor in performing the exposure process. In particular, the wavelength, line width, light continuity, and the like of the light play an important role. As the fine circuit processing technology is developed, the wavelength of light used is also decreasing. In order to obtain such a short wavelength, the light source of the exposure apparatus has been changed from a lamp type to a pulse type laser beam that scans conventional continuous light.

The advantage of the pulsed laser beam is that the wavelength of the light is short and exhibits high light intensity. On the other hand, since the light is discontinuously emitted in the form of pulses rather than continuously with respect to time, the energy per unit pulse is very high, which may damage the lens lying in the light path. In addition, when the pulse period is long in the scanner device, that is, the repetition rate is small, dose control during the scanning becomes difficult.

Referring to FIG. 1, a conventional laser system for manufacturing a semiconductor device includes a seed oscillator 10 for generating seed light and a laser beam oscillator for amplifying the light to amplify the laser beam. It consists of two oscillation chambers and reflectors 30 of a power oscillator 20.

With such a laser system, it is difficult to dramatically increase the repeatability of the laser beam oscillated in the laser beam oscillator. This is because fine impurities in the gas reaction in the oscillation chamber affect the wavelength and intensity, and hence the mechanical limitations of the pump controlling it. Currently, the fastest repetition rate is 4000Hz, and there is a prospect that it will be improved to 6000Hz in the future, but it is required to develop a laser system to increase the repeatability more effectively.

An object of the present invention for solving the above problems is to provide a laser system having a high repeatability.

A laser system for manufacturing a semiconductor device according to an aspect of the present invention for achieving the above object is a seed light oscillator for generating a seed light (sed light), and the path of the seed light to sequentially divide the seed light And a plurality of laser beam oscillators for amplifying the divided lights to form pulsed laser beams, respectively, wherein the lights divided by the optical members are spaced at different times from each other. The optical members are made of an optical retarder material so as to be provided to the laser beam oscillators.

According to one embodiment of the present invention, the optical members according to claim 1, wherein the optical members to focus the light splitters made of the optical retardation material and the pulsed laser beams in one laser beam to split the seed light Includes semi-permeable glasses for

The optical retardation material may include quartz, and the light splitters may be made of quartz having different thicknesses, thereby controlling the time difference.

According to another embodiment of the present invention, the optical members may be made of different optical retardation materials.

According to the present invention described above, at least two laser beam oscillators for oscillating a pulsed laser beam to the seed light oscillator are connected in parallel, and the seed light generated from the seed light oscillator is divided to be different from each other by the optical retardation material. It is provided with laser beam oscillators with a time difference. Therefore, the laser system can easily generate a pulsed laser beam with high repetition rate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments and may be implemented in other forms. The embodiments introduced herein are provided to make the disclosure more complete and to fully convey the spirit and features of the invention to those skilled in the art. In the drawings, the thickness of each device or film (layer) and regions has been exaggerated for clarity of the invention, and each device may have various additional devices not described herein.

2 is a schematic diagram illustrating a laser system according to an embodiment of the present invention.

Referring to FIG. 2, the laser system includes optical members 102, 112, 118, and 122 for sequentially dividing a seed light oscillator 100 and seed light generated from the seed light oscillator 100. , 128, 132, 138, 142, and 148 and a plurality of laser oscillators 110, 120, 130, and 140 for amplifying the divided lights to form pulsed laser beams, respectively.

The laser system may be connected to an exposure apparatus (not shown) such as a scanner or a stepper for performing a photolithography process of the semiconductor device.

The seed light oscillator 100 is called a master oscillator (MO) and generates seed light that becomes a light source of a laser to be generated. For example, although not shown, the seed light oscillator 100 may include a chamber for discharging a gas such as KrF, ArF, and the like, and an electrode for the discharge may be provided in the chamber.

The laser beam oscillator, that is, a power oscillator (PO), amplifies the seed light to oscillate a pulsed laser beam. A plurality of laser beam oscillators are provided, and are connected in parallel with the seed light oscillator 100.

For example, the laser system may be composed of first, second, third and fourth laser beam oscillators 110, 120, 130, 140, i.e. four laser beam oscillators. Can be.

The laser beam oscillators generate a KrF excimer laser beam having a wavelength of 248 nm, an ArF excimer laser beam having a wavelength of 193 nm, an F ₂ laser beam having a wavelength of 157 nm, and the like, depending on the type of gas. In the manufacture of a semiconductor device, the shorter the wavelength can form a smaller pattern on the semiconductor substrate.

The seed light is divided into the laser beam oscillators and provided. To this end, optical members for sequentially dividing the seed light are disposed on a light path of the seed light. The optical members include a plurality of total reflection mirrors, light splitting mirrors and transflective mirrors.

Specifically, the seed light generated by the seed light oscillator 100 is reflected to the first light splitting mirror 112 through the first total reflection mirror 102. The first light splitter 112 reflects a part of the seed light to the first laser beam oscillator 110, and transmits the remaining light toward the second light splitter 122. Similarly, some of the seed light transmitted through the first light splitting mirror 112 by the second and third light splitting mirrors 122 and 132 are respectively directed to the second and third laser beam oscillating units 120 and 130. It is divided and provided. Finally, the remaining light transmitted through the third light splitting mirror 132 is provided to the fourth laser beam oscillator 140 through the second total reflection mirror 142.

The first to fourth laser beam oscillators 110, 120, 130, and 140 respectively amplify the divided lights to oscillate the first to fourth laser beams 115, 125, 135, and 145. As described above, since the laser beams use light divided from the seed light, the laser beams have a relatively smaller intensity than the laser beam oscillated by the whole seed light. Therefore, damage to the lens or the like of the exposure apparatus can be suppressed by increasing the intensity of the laser beam to be oscillated too much.

Here, the first to third light splitters 112, 122, and 132 are all made of an optical retarder material. The optical retardation material refers to a specific material that generates a time delay inside the material in reflecting or transmitting light of a specific wavelength. For example, the light splitters are made of quartz. In this case, the first to third light splitting glasses 112, 122, and 132 may be made of quartz having different thicknesses so that the divided lights are reflected or transmitted with different time differences. That is, the delay time may be controlled by the thickness of the quartz by the refractive characteristic of the quartz.

Alternatively, the first to third light splitters 112, 122, and 132 may be made of different optical delay materials having different time delay effects.

Therefore, the divided lights are provided to the first to fourth laser oscillators 110, 120, 130, and 140 with different time differences, respectively, and the first to fourth laser beams 115, 125, 135, and 145 are provided. This time difference can be generated with substantially the same time difference. For example, the first to fourth laser beams 115, 125, 135, and 145 may be sequentially oscillated.

Meanwhile, the transmittance of the light splitters may vary depending on the number of the laser beam oscillators.

The first laser beam 115 generated as described above is reflected by the third total reflection mirror 118 and provided to the first transflective mirror 128. The transflective mirror functions to transmit or reflect light depending on the angle of incident light. That is, the first semi-transmissive mirror 128 transmits all of the first laser beam 115 and reflects all of the second laser beam 125. Similarly, the third laser beam 135 is totally reflected by the second semi-transmissive mirror 138 and transmitted to the third semi-transmissive mirror 148, and the fourth laser beam 145 is the third semi-transmissive mirror ( 148). Here, the third transflective mirror 148 performs a function opposite to that of the first and second transflective mirrors 128 and 138. That is, the third transflective mirror 148 reflects all of the first to third laser beams 115, 125, and 135, and transmits the fourth laser beam 145.

In general, the first to fourth laser beams 115, 125, 135, and 145 are converged into one beam and the fifth laser beam 150 by the third transflective mirror 148. That is, the fifth laser beam 150 may have a high repeatability by the pulsed laser beams of the first to fourth laser beams 115, 125, 135, and 145 generated with the time difference. The number of the optical members may vary according to the arrangement of the seed light oscillator and the laser beam oscillator.

In the conventional laser system, a significant improvement of the gas pump technology is required to have a high repetition rate. However, in the laser system according to the present invention, a laser beam having a high repeatability can be realized by using a conventional gas pump technique.

The repeatability of the laser beam is proportional to the number of the laser beam oscillators, but there are spatial constraints for maintaining the chamber including the laser beam oscillators.

Although not shown, in addition to the method of physically increasing the repeatability of the laser as in the above embodiment, it is possible to more easily adjust the time delay electrically by using a trigger circuit connected to each of the laser beam oscillators. . Accordingly, the physical method and the electrical method may be used in parallel according to the use environment of the exposure apparatus or the degree of time delay.

3 is a graph for comparing the laser intensity and repeatability of the laser system with a conventional laser system.

Referring to FIG. 3, the oscillation of the laser beams using the four laser beam oscillators illustrated in FIG. 2 is illustrated. The pulse of the fifth laser beam 150 is divided into pulses having a time difference of the first to fourth laser beams 115, 125, 135, and 145, and the group of the respective pulses is It corresponds to one pulse of the conventional laser beam 40. Therefore, it can be seen that the fifth laser beam 150 has a higher repeatability than the conventional laser beam 40.

In addition, as illustrated, the first to fourth lasers 115, 125, 135, and 145 have a smaller pulse intensity than the conventional laser beam 40. By using the fifth laser beam 150 having such low intensity and high repeatability, it is possible to more easily control the dose and the like in the exposure apparatus.

According to the embodiment of the present invention as described above, the repeatability of the laser is increased while the intensity is decreased. Therefore, control of the exposure apparatus such as dose adjustment can be made easier and damage to the exposure apparatus can be reduced. Therefore, the yield of a semiconductor device improves and there exists an effect that the operation rate of an exposure apparatus improves.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (5)

A seed light oscillator for generating seed light; Optical members disposed on a path of the seed light to sequentially divide the seed light; And A plurality of laser beam oscillators for amplifying the divided lights to form pulsed laser beams, respectively, And the optical members are made of an optical retarder material so that the light divided by the optical members is provided to the laser beam oscillators at different time differences, respectively. The optical member of claim 1, wherein the optical members include light splitters made of the optical retardation material and semi-transmissive mirrors for concentrating the pulsed laser beams into a single laser beam to split the seed light. Laser system for manufacturing a semiconductor device. The laser system of claim 1, wherein the optical retardation material comprises quartz. The laser system of claim 3, wherein the light splitting mirrors are made of quartz having different thicknesses so that the time difference is adjusted. The laser system of claim 1, wherein the optical members are made of the different optical retardation materials.

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