KR100887245B1 - Laser Processing Apparatus and Method Using Beam Split - Google Patents

Abstract

A laser processing apparatus and method for effectively removing low-k materials formed on a wafer are provided.

The laser processing apparatus of the present invention divides the laser generating means for emitting a laser beam, the laser beam emitted from the laser generating means into two, so that the interval of the divided laser beam is the interval between two edges of the low dielectric material to be removed. A beam splitting means for splitting and entering a mirror and an optical system for scanning the split laser beam reflected from the mirror to an object, wherein the laser processing method of the present invention comprises the distance between the edge and the position of the edge portion of the region to be removed the low dielectric material Setting processing parameters including the output power of the laser beam, emitting and dividing the laser, and irradiating the two-divided laser beam to two edge portions of the region to be removed, the low dielectric material, respectively.

According to the present invention, low dielectric materials can be effectively and simply removed to improve processing speed and quality.

Low dielectric materials, lasers, edges

Description

Laser processing apparatus and method using laser beam splitting {Laser Processing Apparatus and Method Using Beam Split}

1 is a view for explaining a problem when the low dielectric material removal using a CO ₂ laser,

2 is a block diagram of a laser processing apparatus according to an embodiment of the present invention,

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4 is a view for explaining the result of removing the low dielectric material using the laser processing apparatus of the present invention,

5 is a flowchart illustrating a laser processing method according to an embodiment of the present invention;

6 is a configuration diagram of a laser processing apparatus according to another embodiment of the present invention;

7 is a flowchart illustrating a laser processing method according to another embodiment of the present invention.

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

10, 124: mirror 12: optical system

14 object 16: stage

18: stage transfer means 110: control unit

120, 122: laser generating means 130: beam splitting means

140, 142: mirror drive unit 150: input unit

160: output unit 170: storage unit

TECHNICAL FIELD The present invention relates to laser processing apparatus and methods, and more particularly, to laser processing apparatus and methods for effectively removing low-k materials formed on wafers.

In the semiconductor device manufacturing process, a low dielectric material is used for pattern formation or insulation. Such a low dielectric material has a high viscosity, so that when the wafer is processed by a mechanical method in a subsequent process, the low dielectric material adheres to the saw and not only wears the saw but also reduces the processing speed. In addition, a phenomenon in which the low dielectric material falls off in a mass during processing occurs, the processing surface is not sharp, and the low dielectric material other than the region to be removed falls out, resulting in deterioration of production characteristics.

In order to prevent this problem, a method of preferentially removing low-k dielectric materials prior to actual wafer processing using a laser has been studied. In general laser processing, the aim is to achieve a narrower cutting width, but when removing low dielectric material, the cutting width is larger than the main cutting width for removing the actual low dielectric material, for example, the width of the mechanical sawing. Should be.

As a laser processing method proposed to remove low dielectric materials, there is a method of removing low dielectric materials with a large spot size of 60 μm or more using a laser having a wavelength band of infrared or more. This method can be easily implemented because the configuration of the optical system is relatively easy, and the output power of the laser having an infrared wavelength or more is high, such as 100W or more, so that the processing power can be flexibly applied.

In laser processing, the spot size is determined as shown in Equation 1 below.

[Equation 1]

Spot size = 4λF / πDM ²

In Equation 1, λ is the wavelength of the laser, F is the focal length of the condenser lens, and D is the aperture of the laser beam incident on the condenser lens.

M ² is a factor indicating the quality of the laser beam, and M ² = πw (zo) w (z) / zλ. Here, w (z) is the beam waist after the laser beam has progressed, and w (z0) is the minimum value of the beam waist. Although general light diffuses as it progresses, there is a straightness that the laser beam does not diffuse even as it progresses. In the definition of M ² , z is infinitely approximated to induce M ² , and M ² may be a value ranging from a value close to 1.0 to a value of 30 or more. Thus, generally the longer the wavelength the value of M ² is increased and the expensive equipment, the quality of the more the laser beam little, the value of M ^2.

As can be seen from the above equation, the wavelength of the laser and the focal length of the condenser lens determine the spot size of the laser beam. The focal length of the condenser lens can be varied depending on the design of the equipment.However, the minimum focal length to protect the lens from contamination during processing is about 20mm, and the mass production lens varies depending on the wavelength of the laser. It becomes about 50-300 mm. The spot size of a laser beam having a wavelength greater than or equal to infrared is theoretically about 10 to 100 μm, and the spot size of a laser beam having ultraviolet or visible light wavelength is approximately several μm, and the wavelength is substituted in [Equation 1]. It can be seen that the longer the minimum spot size increases.

In addition, a CO ₂ laser used to remove a low dielectric material or a pattern layer may theoretically have a spot size of 50 μm, and a theoretical limit of 50 ± 10 μm is expected.

1 is a view for explaining a problem when removing a dielectric material using a CO ₂ laser.

As shown, it can be seen that when the low dielectric material is removed using a CO ₂ laser, the processing edge portion A is not sharp due to the melting phenomenon. In addition, silicon, which is a main material of the semiconductor substrate, has a absorption rate of almost zero when a CO ₂ laser having a wavelength longer than that of the visible light is incident, and thus, most beams cannot process silicon and cause damage to the transfer device. .

In addition, the low dielectric material has different mechanical and optical properties from the material used as the substrate of the wafer, such as Si, Ge, GaAs, etc., and thus may exhibit different reactions depending on the wavelength, beam size, and processing parameters of the laser. In some cases, the difference can significantly reduce the quality of processing.

Therefore, when the low dielectric material is removed by using a laser beam, when the type of the wafer is changed or when the width of the processed portion is changed, it is troublesome to newly change the condenser lens or the optical system.

As such, a method of removing the low dielectric material by laser processing has been studied, but studies on the removal of the low dielectric material by mechanical processing have continued, because the above problems exist. When mechanical processing is performed by the method, the result is that the low dielectric material can be more effectively removed. However, in this case, when the width of the mechanical saw for processing the substrate material such as silicon, which is the majority of the workpiece, is large, that is, when the width of the target portion is large, the processing speed is reduced and the processing speed is lowered. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and removes the edge portion of the region to be removed in a region where the low dielectric material is formed by a laser beam, and then removes the low dielectric material remaining between the edge portions. Thereby, the technical problem exists in providing the laser processing apparatus and method using the beam division which can improve the processing efficiency of an object.

According to another aspect of the present invention, an edge portion of a region to be removed in a region in which a low dielectric material is formed is primarily removed by a laser beam, and at the same time, a low dielectric material remaining between edge portions is removed using a laser. By removing, it is possible to improve the processing efficiency and speed of the object.

Laser processing apparatus according to an embodiment of the present invention for achieving the above technical problem is a laser generating means for emitting a laser beam; Beam dividing means for dividing the laser beam emitted from the laser generating means into two parts, dividing the laser beam into a distance between two edges of the low dielectric material to be removed and entering the mirror; And an optical system scanning the split laser beam reflected from the mirror to the object.

In addition, the laser processing apparatus according to another embodiment of the present invention includes a first laser generating means for emitting a laser beam; Beam dividing means for dividing the laser beam emitted from the laser generating means into two parts, dividing the laser beam into a distance between two edges of the low dielectric material to be removed and entering the mirror; An optical system for scanning the split laser beam reflected from the first mirror to an object; Second laser generating means for emitting a laser beam; And a second mirror reflecting the laser beam emitted from the second laser generating means to the first mirror to irradiate the low dielectric material between the two edges.

In addition, the laser processing method according to an embodiment of the present invention comprises the steps of setting the processing parameters including the position and the distance between the edges of the edge portion of the region to be removed low dielectric material, the output power of the laser beam; Emitting and dividing the laser; And irradiating the two divided laser beams to two edge portions of the removal target region low dielectric material, respectively.

In addition, the laser processing method according to another embodiment of the present invention comprises the steps of setting the processing parameters including the position and the distance between the edge of the edge portion of the region to be removed low dielectric material, the output power of the laser beam; Emitting and dividing the first laser; Irradiating the two divided first laser beams to two edge portions of the region to be removed, the low dielectric material; Emitting a second laser; And irradiating the emitted second laser beam between the two edges.

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

2 is a block diagram of a laser processing apparatus according to an embodiment of the present invention.

As shown, the laser processing apparatus according to the present invention includes a control unit 110 for controlling the overall operation, a laser generating means 120 for outputting a laser beam having a specified aperture, and a laser emitted from the laser generating means 120. Beam splitter 130 for dividing the beam into two, mirror driver 140 for driving the mirror 10, input unit 150 for inputting control parameters and control commands, and for displaying information such as operating status Mirror 10 and mirror reflecting the laser beam emitted from the output unit 160, the storage unit 170 for storing data, the beam splitter 130 to the surface of the object 14, the low dielectric material formed thereon ( The optical system 12 collects the laser beam reflected by 10) or converts the shape of the collected laser beam to irradiate the laser beam divided into the edge portion of the region to be removed.

In addition, the object 14 having the low dielectric material formed thereon is seated on the stage 16, and the stage 16 moves in the direction designated by the conveying means 18.

Herein, the mirror 10 may be implemented as a reflective mirror or a polygon mirror. When the mirror 10 is implemented as a polygon mirror, the polygon mirror is manufactured by controlling the number of reflecting surfaces so that the aperture of the laser beam covers a plurality of reflecting surfaces of the polygon mirror. It is preferable to use. On the other hand, for a laser processing apparatus using a polygon mirror was filed in the Republic of Korea by the present applicant on March 31, 2004 (application number: 10-2004-0022270), and the polygon mirror manufactured by controlling the number of reflecting surface The laser processing apparatus used was filed in the Republic of Korea on August 18, 2004 by the present applicant (application number: 10-2004-0065066), and a detailed description thereof will be omitted.

In addition, the optical system 12 may be implemented as a condenser lens, or a condenser lens and a cylindrical lens. When the optical system 12 includes a cylindrical lens, the cross-sectional shape of the laser beam becomes an ellipse shape, and if the long axis of the ellipse is controlled to coincide with the processing direction, more excellent processing efficiency can be obtained.

When the object 14 is processed using the laser processing apparatus, first, control parameters are set through the input unit 150. The setting process is performed by registering a preset menu according to the type and processing type of the object to be stored. Stored at 170, it can be easily performed by calling the menu.

When the control parameter setting is completed, the mirror driving unit 140 adjusts the position of the mirror 10. When the mirror 10 is a polygon mirror, the mirror 10 is rotated at a constant speed according to a preset rotation speed. Then, the controller 110 operates the stage transfer means 18 to transfer the object 14 in a specified direction, and controls the laser generating means 120 to generate the laser beam when the laser beam is emitted. ) Is split into two and is incident on the mirror 10.

Thereafter, at least two laser beams reflected from the mirror 10 are irradiated perpendicularly to two edge portions of the region to be removed of the low dielectric material formed on the surface of the object 14 through the optical system 12. In this case, since the beam passing through the optical system 12 is divided into two beams, two edge portions of the region to be removed may be simultaneously processed.

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4 is a view for explaining the result of removing the low dielectric material using the laser processing apparatus of the present invention.

Referring to FIG. 4, two edges D1 and D2 of the region C in which the low dielectric material to be removed is formed among the low dielectric materials on the entire soil lane B are removed using the laser processing apparatus shown in FIG. 3. The remaining low dielectric material (E) is then removed by subsequent mechanical or laser processing methods.

As shown, it can be seen that the edge portions D1 and D2 of the region to be removed low dielectric material are removed to expose the lower substrate. A low dielectric material remains between the two edge portions D1 and D2, which can be removed by subsequent mechanical or laser processing methods.

First, since the low dielectric material of the edge portion is simultaneously removed by the divided laser beam, it is possible to prevent the low dielectric material other than the region to be removed from falling off when the low dielectric material is removed in a subsequent process, and FIG. 4. As can be seen, the edge portion can be machined accurately and sharply to improve manufacturing properties.

5 is a flowchart illustrating a laser processing method according to an embodiment of the present invention.

In order to process the object having the low dielectric material formed thereon, first, processing parameters are set according to the type and processing form of the object to be processed (S101). For example, the position of the edge portion of the region to be removed and the gap between the edges, the output power of the laser beam, and the like are set as parameters.

Thereafter, the laser is emitted from the laser generating means 120 (S103), and then the stage is moved by the stage transfer means 18 to transfer the object 14 in the direction opposite to the machining direction (S105). The object transfer is not an essential process, and when the object is transferred in a direction opposite to the processing direction, the processing speed can be improved.

The laser beam emitted from the laser generating means 120 is split in two in the beam splitting means 130 and is incident through the mirror 10 and the optical system 12 to the two edges of the region of low dielectric material to be removed. The edge portion is to be removed (S107).

In this way, after the edge portion of the region to be removed is removed, the low dielectric material remaining between the two edges is removed using a mechanical method or a laser processing method (S109).

In this embodiment, the processing of the edge portion of the region to be removed low dielectric material and the processing of the low dielectric material remaining between the two edges are performed independently, so if the two processes are performed simultaneously, the processing speed can be further improved. It is expected. This will be described with reference to FIGS. 6 and 7 as follows.

6 is a block diagram of a laser processing apparatus according to another embodiment of the present invention.

In addition to the laser processing apparatus shown in FIG. 2, the laser processing apparatus according to the present embodiment further includes a second laser generating means 122, a second mirror 124, and a second reflection mirror driver 142.

The first laser beam emitted from the first laser generating means 120 is divided into two by the beam splitting means 130, and the object having the low dielectric material formed thereon through the first mirror 10 and the optical system 12 ( 14). At this time, the divided two laser beams are irradiated to the two edge portions of the region to be removed low dielectric material, to remove the low dielectric material of the two edge portions.

On the other hand, the second laser beam emitted from the second laser generating means 122 is reflected by the second mirror 124, the object 14, the low dielectric material is formed through the first mirror 10 and the optical system 12 Is investigated. At this time, the second laser beam is irradiated between the two edges of the region to be removed, the low dielectric material to remove the low dielectric material remaining between the edges after the two edges are removed by the divided first laser beam.

Here, the second laser generating means 122 is preferably driven after a predetermined time has elapsed after the first laser generating means 120 is driven, and the laser beam emitted from the second laser generating means 122. The spot size of is preferably set to a value obtained by subtracting the widths of the two edges removed by the divided first laser beam from the width of the region to be removed.

On the other hand, the laser emitted from the second laser generating means 122 may be any one of UV ViS (Ultra Violet Visible), IR (Intra Red), CO ₂ laser. Here, UV ViS means light from the ultraviolet region to the visible region, IR means infrared rays, CO ₂ laser means a carbon dioxide laser.

7 is a flowchart illustrating a laser processing method according to another embodiment of the present invention.

In order to simultaneously process the residue between the removal target region edge and the edge of the object having the low dielectric material formed thereon, first, the processing parameters are set according to the type and processing type of the processing target (S201). For example, the position of the edge portion of the region to be removed and the gap between the edges, the output power of the first and second laser beams, and the like are set as parameters.

Thereafter, the first laser is emitted from the first laser generating means 120 (S203), and then the stage is moved by the stage transfer means 18 to transfer the object 14 in the direction opposite to the machining direction (S205). . The object transfer is not an essential process, and when the object is transferred in a direction opposite to the processing direction, the processing speed can be improved.

The laser beam emitted from the first laser generating means 120 is split in two in the beam splitting means 130, and is incident to the two edges of the region to be removed of the low dielectric material through the first mirror 10 and the optical system 12. Accordingly, the edge portion is removed (S207).

Thereafter, the second laser is emitted from the second laser generating means 122 (S209), and the second laser beam is stored through the second mirror 124, the first mirror 10, and the optical system 12. Scanning between the two edges of the dielectric material to remove the low-k material remaining between the two edges (S211).

As described above, by removing the edge portion of the region to be removed and the low dielectric material remaining between the two edges, the object can be processed with excellent processing characteristics while maintaining a high speed operation of 200 mm / s or more.

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.

According to the present invention, in removing the low dielectric material, the edge portion of the region to be removed is removed by using a laser beam divided into two parts, and then the low dielectric material remaining between the edges is removed, thereby improving processing quality. Can be improved.

In addition, when the edge portion of the region to be removed is removed by a laser beam divided into two, and when the low dielectric material remaining between the edges is removed together, the processing speed can be improved, thereby maximizing the processing efficiency. have.

Claims (21)

A laser processing apparatus for processing an object having a low dielectric material formed thereon, Laser generating means for emitting a laser beam; Beam dividing means for dividing the laser beam emitted from the laser generating means into two parts, dividing the laser beam into a distance between two edges of the low dielectric material to be removed and entering the mirror; And An optical system for scanning the split laser beam reflected from the mirror to the object; Laser processing apparatus comprising a. delete delete The method of claim 1, And said mirror is a polygon mirror. The method of claim 1, And the mirror is a polygon mirror manufactured by controlling the number of reflecting surfaces so that the aperture of the laser beam covers the plurality of reflecting surfaces of the polygon mirror. A laser processing apparatus for processing an object having a low dielectric material formed thereon, First laser generating means for emitting a laser beam; Beam dividing means for dividing the laser beam emitted from the laser generating means into two parts, dividing the laser beam into a distance between two edges of the low dielectric material to be removed and entering the mirror; An optical system for scanning the split laser beam reflected from the first mirror to an object; Second laser generating means for emitting a laser beam; And A second mirror reflecting a laser beam emitted from the second laser generating means to the first mirror to irradiate with a low dielectric material between the two edges; Laser processing apparatus comprising a. The method of claim 6, And the second laser generating means is driven after a predetermined time elapses after driving of the first laser generating means. The method of claim 6, And the aperture of the laser beam emitted from the second laser generating means is controlled to be a distance between the two edges. delete delete The method of claim 6, And said first mirror is a polygon mirror. The method of claim 6, And the first mirror is a polygon mirror manufactured by controlling the number of reflecting surfaces so that the aperture of the laser beam covers the plurality of reflecting surfaces of the polygon mirror. A laser processing method for processing an object having a low dielectric material formed thereon, Setting processing parameters including the position and edge spacing of the edge portion of the region to be removed low dielectric material and the output power of the laser beam; Emitting and dividing the laser; And Irradiating the two divided laser beams to two edge portions of the region to be removed, the low dielectric material; Laser processing method comprising a. delete delete delete A laser processing method for processing an object having a low dielectric material formed thereon, Setting processing parameters including the position and edge spacing of the edge portion of the region to be removed low dielectric material and the output power of the laser beam; Emitting and dividing the first laser; Irradiating the two divided first laser beams to two edge portions of the region to be removed, the low dielectric material; Emitting a second laser; And Irradiating the emitted second laser beam between the two edges; Laser processing method comprising a. delete delete delete The method of claim 17, And the aperture of the second laser beam is controlled to be a distance between the two edges.

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