KR100391226B1 - Laser Beam Spltting System and Surface Treatment Method using The Same - Google Patents

Abstract

Provided are a laser beam splitting apparatus for surface treatment such as cleaning and planarization of semiconductors and optical devices, and a surface treatment method using the same.

The laser beam splitting apparatus includes at least two beam transmitters for collecting and transmitting a laser beam emitted from a laser light source, a beam detector for measuring the energy intensity of the laser beam incident through the beam transmitter, and a single beam output from the beam detector. And a control unit for adjusting the reference energy level of the beam splitter and the beam detector, and the angle of the beam emitted from the beam splitter. The at least two divided laser beams are irradiated onto the surface of the substrate to be processed, each having a predetermined energy level and angle of incidence, installed on the stage in the chamber.

According to the beam splitting apparatus and the surface treatment method using the same, the surface treatment of the substrate can be performed with a small number of scanning times, thereby improving the efficiency of the surface treatment process and reducing the time required. In addition, when the substrate is installed perpendicular to the stage, both surfaces of the substrate can be processed simultaneously, and the surface treatment effect can be further enhanced, such as preventing the particles from reattaching.

Description

Laser Beam Splitting System and Surface Treatment Method using The Same

The present invention relates to an apparatus and method for precisely controlling the surface states of semiconductors and optical devices, and more particularly, to a laser beam splitting device and a surface using the same for surface treatment of semiconductors, optical devices, precision mechanical devices and materials. It is about a processing method.

The manufacture of semiconductors and optical devices goes through several steps. At this time, an unnecessary thin film is formed on the substrate on which each process is performed, and various contaminants are attached. For example, it is known that a semiconductor wafer has a root mean square (RMS) surface roughness of 1 to 2 GPa per 2 탆 x 2 탆. Therefore, a subsequent process such as controlling the surface roughness of the target substrate for a certain time is essential.

Currently, surface treatment of semiconductor devices, optical devices, and the like is performed by a wet process in the cleaning process and a chemical mechanical polishing (CMP) method in the surface planarization process. However, as the device becomes finer, wet cleaning alone may not completely remove contaminants attached to the substrate, and there is a problem in that water marks occur after cleaning.

On the other hand, the surface planarization method using CMP is to precisely process the surface by adding a chemical, slurry, pure water (D.I. Water) while pressing and rotating the material that needs to be surface-treated at an appropriate pressure. However, because the CMP method uses slurries and hazardous chemicals, it causes environmental pollution, and enormous costs are required for the pollution prevention equipment required for the reprocessing of chemicals. In addition, since the CMP treatment is always followed by a cleaning process, the process efficiency is lowered, and because of the contact method, physical stress is applied to the surface of the target substrate, and there is a risk of damaging the substrate if severe. Accordingly, when the polishing rate is lowered in order to prevent damage to the substrate, the processing time is increased and the yield is lowered. In addition, in the case of a material having high strength, there is a problem in that the surface of the substrate cannot be polished by the CMP method.

In order to solve such problems as wet cleaning and CMP abnormalities, a surface treatment method using a laser beam is currently being studied. Since the laser can emit light with a strong energy instantaneously, it has the advantage of quickly removing all or a portion of the surface that is hard to be mechanically polished or wetted by irradiating a hard surface.

Current laser surface treatment equipment uses a single beam oscillating from a laser source. In general, the laser beam is processed in the form of a line beam having a beam width of 0.5 to 2 mm and a beam length of 50 to 200 mm, so that the surface treatment of the substrate can be performed in one scan.

Referring to FIG. 3, when cleaning the semiconductor substrate 50 on which the pattern 52 is formed, the angle of the beam to be irradiated is removed when a foreign matter on the side of the hole or the groove is removed by using a single laser beam. The cleaning effect is adjusted to increase the cleaning effect. In this case, the cleaning process requires a lot of time because the substrate needs to be scanned one more time by rotating the substrate to clean the portion A not directly irradiated with the beam.

On the other hand, the ultra-fine processing technology using excimer laser is applied to the material deposition or evaporation required for the processing of micro parts processing and the development of process materials requiring fine processing in manufacturing in the fields of semiconductor, communication, optics, electronic parts, and micro precision machinery. The application area is gradually expanding.

The ultra-fine processing technology using this excimer laser is based on the conventional laser processing by thermal processing by focused beam, while the excimer laser processing in the ultraviolet region is a non-contact, extremely small amount of material due to the thermal reaction to the material and the optical reaction. It is known that it is useful for improving the surface quality and precision of the processed surface by controlling the energy of the UV laser irradiated according to the type of material so that the processing depth can be controlled with the accuracy of several micrometers to sub㎛ per pulse. have. Moreover, the excimer laser beam is effective in minimizing damage to the object to be treated because the excimer laser beam removes the tissue by directly destroying the molecular bonds of the tissue to be removed and the temperature rise due to the absorption of the laser beam.

The present invention has been made to solve the above-mentioned problems, the surface treatment of the semiconductor and the optical device is divided into two or more beams irradiated from the light source during the surface treatment to precisely control the surface processing of the device, The technical challenge is to reduce the time.

Another technical problem of the present invention is to prevent energy loss of the surface treatment equipment and improve the efficiency of the equipment.

1 is a view for explaining the structure of a laser beam splitting apparatus according to the present invention.

2 is a view for explaining a surface treatment method of a substrate using a laser beam output from the laser beam splitting apparatus according to the present invention.

3 is a view for explaining a surface treatment method of a substrate using a single laser beam.

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

10: laser light source 20: beam transmission unit

30: beam detector 40: beam splitter

50: substrate 52: pattern

60 control unit 70 first beam forming unit

80: second beam forming portion 90: stage

100 chamber 102 shutter

104: first mirror 106: spherical lens

108: second mirror 110: first beam splitter

112: energy detector 114: second beam splitter

116: first cylindrical lens 118: third mirror

120: first aperture 122: fourth mirror

124: second cylindrical lens 126: second aperture

The present invention for achieving the above-described technical problem is a device for dividing a laser beam used for surface treatment of semiconductor and optical elements, the beam transmission unit for condensing and transmitting the laser beam emitted from the laser light source, through the beam transmission unit A beam detector for measuring the energy intensity of the incident laser beam, a beam splitter for splitting a single beam output from the beam detector into at least two beams, a reference energy level of the beam detector, and a beam output from the beam splitter It includes a control unit for adjusting the angle.

Here, the beam splitter may include a beam splitter for splitting the beam incident from the beam detector, a first beam former for shaping the first beam emitted from the beam splitter, and a filter for filtering the beam emitted from the first beam former. A first aperture, a second beam former for shaping the second beam emitted from the beam splitter, and a second aperture for filtering the beam emitted from the second beam former. In a preferred embodiment of the present invention, the laser light source uses an excimer laser, and the first and second beam shaping parts consist of a cylindrical lens and an optical mirror.

In addition, the present invention for achieving the above object is a method for surface treatment of the object installed on the stage in the chamber, condensing a laser beam emitted from a laser light source, by measuring the energy intensity of the focused laser beam Adjusting to a predetermined energy, dividing the laser beam into at least two beams, adjusting an angle of incidence of the split laser beam incident on the irradiated object, and subjecting the irradiated object installed on the stage to the Irradiating each of the divided laser beams.

Here, the substrate is installed vertically or horizontally with respect to the stage, and when the substrate is installed vertically, if the divided laser beams are irradiated to the front and rear surfaces of the substrate, surface treatment may be simultaneously performed on both sides of the substrate.

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

1 is a view for explaining the structure of a laser beam splitting apparatus according to the present invention, which shows a case of splitting a laser beam into two. In a preferred embodiment of the present invention, an excimer laser is used as the laser source, and a CO ₂ laser, an Nd: YAG laser, or the like may be used.

As shown, the beam splitting apparatus of the present invention measures the energy intensity of the laser beam when the laser beam emitted from the laser light source 10 is incident through the beam transmitting unit 20, and outputs a beam having an appropriate intensity of energy. The beam detector 30 and the beam splitter 40 for splitting a single beam output from the beam detector 30 into at least two beams. The shutter 102 is installed between the laser light source 10 and the beam delivery unit 20 to prevent the laser beam from being scanned into the device when the irradiation of the beam is unnecessary, such as a setting process of the device, and the beam splitter 30 The laser beam, which is divided into a plurality, is scanned on the target substrate 50 installed on the stage 90 in the chamber 100 for surface treatment.

The controller 60 turns on / off the shutter 102 and adjusts the energy level of the beam detector 30 and the angle of the beam incident on the target substrate 50 according to the characteristics of the substrate 50 to be processed. Control overall operation. The substrate 50 to be processed may be a semiconductor or optical-related product or material such as a silicon wafer, an optical mirror, a lens, or the like.

The operation of the beam splitting apparatus will be described in more detail as follows. The beam emitted from the laser light source 10 passes through the shutter 102 and then passes through the beam transmitting part 20 composed of the first mirror 104, the spherical lens 106, and the second mirror 108. It enters into the division part 30. The first and second mirrors 104 and 108 reflect the incident beam so as to be refracted at a predetermined angle, and the spherical lens 106 has a light collecting effect.

The first beam splitter 110 divides the incident single beam into two and transmits one of them to the energy detector 112. The energy detector 112 senses the energy of the laser beam incident from the first beam splitter 110, and the controller 60 determines whether the energy of the sensed laser beam is an energy level suitable for the characteristics of the substrate to be surface treated. . If the energy level is not appropriate, the controller 60 drives the shutter 102 to block the laser beam from entering the apparatus, and is emitted from the laser light source 10 according to the sensing result of the energy detector 112. Allow the energy of the laser beam to be reconditioned. On the other hand, when the energy level of the incident beam is appropriate, the other beam split by the first beam splitter 110 is incident to the beam splitter 40.

The beam incident to the beam splitter 40 is split again in the second beam splitter 114, and the split first laser beam B1 is incident to the first beam shaping unit 70. The first beam B1 incident on the first beam shaping unit 70 is deformed in a line shape in the first cylindrical lens 116, is refracted in the third mirror 118, and then the first aperture 120. Incident. The first aperture 120 serves to filter a portion having a low intensity of the laser beam incident in a line shape, and the laser beam filtered by the first aperture 120 has a predetermined angle θ ₁ and is processed. Incident on the target substrate 50.

Meanwhile, the other laser beam B2 emitted from the second beam splitter 114 is incident to the second beam shaping unit 80. The second beam B2 incident on the second beam shaping unit 80 is refracted by the fourth mirror 122 and deformed into a line shape by the second cylindrical lens 124 to the second aperture 126. Incident. The second beam B2 is incident on the substrate 50 to be processed at a predetermined angle θ ₂ after the low intensity portion of the second aperture 126 is filtered. Although the first beam B1 and the second beam B2 are preferably adjusted to have angles symmetrical with each other, the first beam B1 and the second beam B2 may have an appropriate angle according to the pattern formation state and characteristics of the target substrate 50.

If necessary, by adding a beam splitter and a beam molding unit to the rear end of the second beam splitter 114 of the beam splitter 40, the laser beam may be split into a desired number.

2 is a view for explaining a surface treatment method of a substrate using a laser beam output from the laser beam splitting apparatus according to the present invention.

When cleaning the semiconductor substrate 50 having the pattern 52 formed thereon, the beam splitting apparatus of the present invention divides the single laser beam into at least two or more and injects the plurality of divided beams into the processing target substrate 50. . In this case, since the laser beam can be simultaneously scanned on both sides of the hole or the groove as shown, the number of scanning for the surface treatment process can be reduced.

On the other hand, due to the ultra miniaturization of the device, surface treatment for not only the front surface of the substrate but also the back surface is required. This is because the particles on the back of the substrate cannot be installed flat during the subsequent process, and thus the accuracy of the process is lowered. In a preferred embodiment of the present invention, by installing the substrate to be processed perpendicular to the stage and controlling the angle of incidence so that the laser beam can be irradiated to the front and back sides of the substrate, the time required for surface treatment of the substrate can be further shortened. Can be. In addition, when the substrate is installed vertically, particles dropped from the substrate during the surface treatment fall down due to the gravity effect, thereby preventing reattachment to the substrate.

In practice, semiconductor wafers have an RMS surface roughness of 1 to 2 dB per 2 μm × 2 μm. When surface treatment is performed using the laser beam splitting apparatus of the present invention, it is possible to obtain an RMS surface roughness of about 0.7 μs. there was.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

The present invention described above can improve the efficiency of the surface treatment process, including cleaning and surface planarization, by dividing a single laser beam used for the surface treatment of semiconductor and optical elements into at least two, and can shorten the time required for the process. have.

In addition, laser cleaning is environmentally friendly because it does not use harmful chemicals, pure water, slurries, etc. unlike current wet cleaning, and unlike CMP technology, laser cleaning is a non-contact method, which prevents physical stress and defects on the surface of the substrate. It can be minimized.

On the other hand, if the substrate is installed perpendicular to the stage and the divided laser beams are irradiated to the front and the back of the substrate, respectively, both sides of the substrate can be cleaned at the same time, and particles can be prevented from reattaching, thereby further improving the surface treatment effect. Can be.

Claims (8)

An apparatus for dividing a laser beam used for surface treatment of semiconductors and optical elements, A beam transmission unit for collecting and transferring the laser beam emitted from the laser light source; A beam detector for measuring an energy intensity of the laser beam incident through the beam transmitter; A beam splitter configured to split the single beam output from the beam detector into at least two beams; And A controller for adjusting a reference energy level of the beam detector and an angle of a beam emitted from the beam splitter; Laser beam splitting device comprising a. According to claim 1, And the laser light source is an excimer laser. According to claim 1, The beam splitter may include a beam splitter for splitting a beam incident from the beam detector; A first beam shaping unit for shaping the first beam emitted from the beam splitter; A first aperture for filtering the beam emitted from the first beam shaping unit; A second beam shaping part for shaping a second beam emitted from the beam splitter; And A second aperture for filtering the beam emitted from the second beam shaping unit; Laser beam splitting device comprising a. The method of claim 3, wherein And the first beam shaping unit comprises a cylindrical lens and an optical mirror. The method of claim 3, wherein And the second beam shaping unit comprises a cylindrical lens and an optical mirror. A method for surface treatment of an object installed on a stage in a chamber, Condensing a laser beam emitted from the laser light source; Measuring an energy intensity of the focused laser beam and adjusting the energy intensity to a predetermined energy; Dividing the laser beam into at least two beams; Adjusting an incident angle at which the split laser beam is incident on the irradiated object; Irradiating each of the divided laser beams onto an irradiation object installed on the stage; Surface treatment method comprising a. The method of claim 6, The laser light source is a surface treatment method using an excimer laser. The method of claim 6, And the irradiated object is installed vertically or horizontally with respect to the stage.