Laser device and processing device including same

Abstract

A laser device and a laser processing device including same are disclosed. The laser device disclosed herein comprises: a pulse beam generation unit for generating a shaped pulse laser beam; a first optical amplification unit for amplifying the pulse laser beam generated by the pulse beam generation unit; and a control unit for controlling the pulse beam generation unit to generate a shaped pulse laser beam having a shape in which the slope before a peak value of the pulse laser beam is gentle and the slope after the peak value is steeper than the slope before the peak value.

Description

Laser device and processing device including the same

[0001] It relates to a laser device and a processing device including the same.

[0002] The semiconductor process of manufacturing semiconductor devices using semiconductor materials such as silicon can be divided into semiconductor pre-process and semiconductor post-process. The semiconductor pre-process may include a process of forming a desired circuit pattern on a semiconductor wafer (e.g., a silicon wafer) using photolithography technology and forming multiple semiconductor devices to be manufactured, such as transistors and light-emitting devices. The semiconductor post-process may include a cutting process of cutting a semiconductor wafer on which multiple semiconductor devices have been formed into chips, and a packaging process of packaging the multiple cut semiconductor chips.

[0003] In this laser processing technology, in order to improve the cutting power of semiconductor wafers, it is advantageous for a long uniform length to be generated when the laser light is irradiated once.

[0004] A laser device capable of generating a long uniform length when laser light is irradiated once and a processing device including the same are provided.

[0005] A laser device according to one type includes: a pulse beam generator for generating a shaped pulse laser beam; a first optical amplifier for amplifying the pulse laser beam generated from the pulse beam generator; and a control unit for controlling the pulse beam generator to generate the shaped pulse laser beam in a shape in which the forward slope relative to the peak value of the pulse laser beam is gentle and the backward slope is steeper than the forward slope.

[0006] When the pulse width of the pulse laser beam is Tp, the forward width reaching the peak is T1, and the backward width thereafter is T2, the pulse laser beam can satisfy the condition of T1 > T2 (wherein, Tp = T1 + T2).

[0007] The ratio of T1 to Tp (T1 / Tp) may be 0.7 or greater.

[0008] The pulse beam generating unit may include a laser element that generates a pulse laser beam, and may be configured to generate the pulse laser beam formed from the laser element by applying a control signal from the control unit.

[0009] The pulse beam generating unit includes a light source unit that generates a pulse laser beam; and an optical modulator that shapes the pulse laser beam generated from the light source unit; and by applying a control signal from the control unit to the optical modulator, the pulse laser beam generated from the light source unit can be shaped by the optical modulator.

[0010] The above light source unit may include a laser element that generates a pulsed laser beam.

[0011] The above light source unit may include a pumping laser element that provides a pump beam; and a second optical amplifier unit having a gain medium that amplifies the pump beam to generate the pulsed laser beam.

[0012] The above light source unit may further include a coupler that couples the pump beam onto the path of the second optical amplifier unit.

[0013] The above gain medium may include a gain optical fiber.

[0014] The second optical amplifier may further include a pair of optical fiber Bragg gratings arranged on both sides of the gain optical fiber.

[0015] Light transmission within the pulse beam generator can be accomplished via an optical fiber.

[0016] A first isolator may further be included between the pulse beam generator and the first optical amplifier.

[0017] The first optical amplifier may include a gain medium that amplifies the pulsed laser beam with a pump beam provided from a pumping laser element; and a coupler that couples the pump beam onto a path of the pulsed laser beam.

[0018] The above gain medium may include a gain optical fiber.

[0019] The above first optical amplification unit may include a plurality of optical amplification units.

[0020] A second isolator may be further included between the plurality of optical amplifiers and at least one of the output terminals of the final optical amplifier.

[0021] The above first optical amplifier may further include a second isolator at the output terminal.

[0022] Light transmission within the above first optical amplification unit can be achieved through an optical fiber.

[0023] A laser processing device according to a type of work includes the above-described laser device; and a focusing optical system for focusing a shaped pulse laser beam provided from the laser device onto a processing target.

[0024] The method may further include a stage on which the processing object is placed; and a stage position control unit for controlling the position of the stage.

[0025] According to a laser device according to an embodiment and a processing device including the same, by forming a pulse laser beam into a shape in which a forward slope based on a peak is gentle and a backward slope is steeper than the forward slope, when the pulse laser beam is irradiated once, a uniform length is generated, so that the number of laser beam irradiations for cutting a semiconductor wafer can be reduced, thereby shortening the processing time.

[0026] Figure 1 schematically shows a laser device and a laser processing device according to an embodiment.

[0027] Figures 2 and 3 exemplarily show embodiments of the pulse beam generator of Figure 1.

[0028] Fig. 4 shows an example of a laser device according to an embodiment configured to apply the pulse beam generator of Fig. 2 and transmit light through an optical fiber.

[0029] Fig. 5 shows an example of a laser device according to an embodiment configured to apply the pulse beam generator of Fig. 3 and transmit light through an optical fiber.

[0030] FIG. 6a and FIG. 6b show the waveform of a pulsed laser beam formed by a laser device according to an embodiment (waveform of the embodiment), FIG. 6a shows a measured waveform, and FIG. 6b shows the relationship between the front width and the rear width of the waveform shown in FIG. 6a.

[0031] Figures 7a and 7b show the waveform of a Gaussian pulse laser beam corresponding to the basic waveform (waveform of Comparative Example 1). Figure 7a shows the measured waveform, and Figure 7b shows the relationship between the front width and the rear width of the waveform shown in Figure 7a.

[0032] Figures 8a and 8b show the waveform of the pulse laser beam of Comparative Example 2 (waveform of Comparative Example 2). Figure 8a shows the measured waveform, and Figure 8b shows the relationship between the front width and the rear width of the waveform shown in Figure 8a.

[0033] Figures 9 to 11 are graphs showing the results of evaluating the amount of cracks according to the power (unit: W) and defocus of the pulsed laser beam of Examples, Comparative Example 1, and Comparative Example 2.

[0034] Figure 12 shows a comparison of the length of a crack according to the pulse width and pulse rise time of a shaped pulse laser beam (example waveform) formed by a laser device according to an embodiment.

[0035] Figures 13 to 15 are graphs showing the results of evaluating the scattered beam by defocus when the pulse laser beam has a high output of 2 W or more.

[0036] Figures 16a to 16c are graphs showing the BHC (Backside half cut) generation height at frequencies of 100 kHz, 120 kHz, and 140 kHz when applying a pulse laser beam of the basic waveform (Comparative Example 1).

[0037] Figures 17a to 17c are graphs showing the BHC generation height at frequencies of 100 kHz, 120 kHz, and 140 kHz when a pulse laser beam of an exemplary waveform is applied.

[0038] Hereinafter, exemplary embodiments will be described in detail with reference to the attached drawings. In the drawings below, like reference numerals designate like components, and the sizes of each component in the drawings may be exaggerated for clarity and convenience. The embodiments described below are merely exemplary, and various modifications are possible from these embodiments.

[0039] Hereinafter, the terms "upper" or "upper" may include not only those directly above, below, left, or right in contact, but also those directly above, below, left, or right in non-contact. Singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, when a part is said to "include" a component, this does not exclude other components, but rather includes other components, unless otherwise specifically stated.

[0040] The use of the term "above" and similar referential terms may refer to both the singular and the plural. Unless the steps of a method are explicitly stated in a specific order or to the contrary, the steps may be performed in any appropriate order, and the order stated is not necessarily limited to that order.

[0041] Additionally, terms such as “part”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

[0042] The lines connecting or disconnecting between components depicted in the drawings are merely representative of functional connections and / or physical or circuit connections, and may be replaced or represented as various additional functional connections, physical connections, or circuit connections in an actual device.

[0043] Any use of examples or exemplary terms is merely intended to elaborate technical ideas and is not intended to limit the scope of the invention unless otherwise defined by the claims.

[0044] A laser processing device is a device that uses a focusing lens to focus a laser beam into a single focal point and irradiates the focus onto the surface or interior of a processing target to process the beam. According to an embodiment, a laser device is provided to improve the processing performance of a laser processing device by modifying the pulse shape of the laser light.

[0045] The laser device according to the embodiment can be applied to, for example, a stealth dicing type laser processing device that focuses laser light inside a semiconductor wafer to form a modified region, and causes the semiconductor wafer to be cut by cracks generated from the modified region, during a cutting process included in a semiconductor post-process. In addition, the laser device according to the embodiment can be applied to various types of laser processing devices that require improved processing performance.

[0046] Fig. 1 schematically shows a laser device (10) and a laser processing device (1) according to an embodiment.

[0047] Referring to FIG. 1, a laser processing device (1) includes a laser device (10) and a focusing optical system that focuses a shaped pulse laser beam provided from the laser device (10) onto a processing target. The laser processing device (1) may further include a stage on which the processing target is placed and a stage position control unit (11) that controls the position of the stage. The laser processing device (1) may perform a processing process, for example, a cutting process, by irradiating the shaped pulse laser beam (Ls) obtained by the laser device (10) according to the embodiment.

[0048] A laser device (10) according to an embodiment includes a pulse beam generator (20) that generates a shaped pulse laser beam, an optical amplifier (50) that amplifies the pulse laser beam generated by the pulse beam generator (20), and a control unit (11) that controls the pulse beam generator (20) to generate the shaped pulse laser beam. The laser device (10) according to the embodiment can output a pulse laser beam (Ls), and the pulse laser beam (Ls) may be amplified compared to a pulse laser beam (Ls') generated by the pulse beam generator (20). The pulse laser beam generated by the laser device (10) according to the embodiment has an intensity-variable waveform, and may have a pulse waveform of a Gaussian shape or a shape similar thereto. For example, a pulse laser beam before beam shaping may have a pulse waveform of a Gaussian shape, and the waveform of the pulse laser beam may be modified by beam shaping. By a control signal applied from the control unit (11), the pulse beam generator (20) can be controlled to generate a pulse laser beam shaped in a shape in which the forward slope based on the peak value of the pulse laser beam is gentle and the backward slope is steeper than the forward slope. In Fig. 1, Ls' represents a shaped pulse laser beam generated from the pulse beam generator (20), and Ls represents a shaped pulse laser beam output from the laser device (10) via the optical amplifier (50).

[0049] Figures 2 and 3 exemplarily show embodiments of the pulse beam generator (20) of Figure 1.

[0050] Referring to FIG. 2, the pulse beam generating unit (20) includes a laser element (LD) 21 that generates a pulse laser beam, and may be arranged to generate a pulse laser beam (Ls') shaped in the laser element (21) in a direct modulation manner. In the present embodiment, the control unit (11) applies a control signal to the laser element (21), and the laser element (21) may be controlled to generate a pulse laser beam (Ls') shaped in a shape in which a forward slope based on a peak value of the pulse laser beam is gentle and a backward slope is steeper than the forward slope. The shaped pulse laser beam (Ls') generated in the laser element (21) may be a beam modified with respect to an intensity-variable pulse beam, for example, a pulse beam having a Gaussian waveform.

[0051] In this way, the pulse beam generating unit (20) of the laser device (10) can be arranged to apply a control signal to the laser element (21) to output a pulse laser beam (Ls') formed from the laser element (21).

[0052] As another example, referring to FIG. 3, the pulse beam generating unit (20) may include a light source unit (30) that generates a pulse laser beam, and a light modulator (40) that shapes the pulse laser beam generated from the light source unit (30). In the present embodiment, the control unit (11) may apply a control signal to the light modulator (40), and the light modulator (40) may be controlled to shape the pulse laser beam input from the light source unit (30) into a shape in which the forward slope relative to the peak value is gentle and the backward slope is steeper than the forward slope, thereby outputting the shaped pulse laser beam (Ls').

[0053] The light source unit (30) may include an optical amplifier unit (25) that amplifies a pump beam provided from a pumping laser element (26), as exemplarily shown in FIG. 5. The pump beam may be a pulse beam, for example, a pulse beam having a Gaussian waveform or a pulse beam having a variable intensity.

[0054] The optical modulator (40) may include, for example, an acousto-optic modulator (AOM). During the beam shaping mode, the optical modulator (40), for example, the acousto-optic modulator, may be maintained in an on state. The control signal of the control unit (11) may be provided to the acousto-optic modulator as electrical power, for example, RF power. Pulsed laser beam shaping may be achieved by adjusting the electrical power, for example, RF power, applied to the acousto-optic modulator. The shaped pulsed laser beam (Ls') may be output from the optical modulator (40), for example, the acousto-optic modulator. As another example, the optical modulator (40) may include a spatial light modulator (SLM). The spatial light modulator may include a silicon substrate, a driving circuit, pixel electrodes, etc., and may adjust the phase of the laser light by adjusting the voltage applied to each pixel electrode, and may modulate the input laser pulse into a desired shape.

[0055] Meanwhile, the laser device (10) according to the embodiment described with reference to FIGS. 2 and 3 can be arranged so that light transmission is achieved through an optical fiber (37), as exemplarily shown in FIGS. 4 and 5.

[0056] Fig. 4 shows an example of a laser device (10) according to an embodiment configured to transmit light through an optical fiber (37). Fig. 4 shows an example of a laser device (10) according to an embodiment applying the pulse beam generator (20) of Fig. 2.

[0057] Referring to FIG. 4, a laser device (10) according to an embodiment includes a pulse beam generating unit (20) that generates a shaped pulse laser beam and an optical amplifying unit (50), and light transmission within the laser device (10) can be arranged to be performed through an optical fiber (37).

[0058] The pulse beam generating unit (20) includes a laser element (21) that generates a pulse laser beam, as described with reference to FIG. 2, and may be arranged to output a pulse laser beam shaped from the laser element (21) in a direct modulation manner. A control signal from the control unit (11) is applied to the laser element (21), and a pulse laser beam (Ls') shaped from the laser element (21) may be generated. The shaped pulse laser beam (Ls') output from the laser element (21) may be transmitted to the optical amplifier (50) using an optical fiber (37) as a transmission path. The pulse laser beam (Ls') may be amplified and output from the optical amplifier (50).

[0059] The optical amplification unit (50) may be formed as a single structure or may include a plurality of optical amplification units (50), and light transmission within the optical amplification unit (50) may be arranged to be performed, for example, through an optical fiber (37). As exemplarily shown in FIG. 4, in the case of including a plurality of optical amplification units (51)(55), an isolator (33) may be further provided between the optical amplification units (51)(55) to prevent reverse transmission of light between the optical amplification units (51)(55). FIG. 4 shows an example in which the optical amplification unit (50) includes two optical amplification units (51)(55), and an isolator (33) is provided between the two optical amplification units (51)(55).

[0060] The optical amplifier (51)(55) may include a gain medium (54)(58) that amplifies a pulsed laser beam transmitted from a pulsed beam generator (20) using a pump beam provided from a pumping laser element (52)(56), and a coupler (53)(57) that couples the pump beam onto the propagation path of the pulsed laser beam. The gain medium (54)(58) may amplify the pulsed laser beam using the pump beam on the propagation path of the pulsed laser beam. The gain medium (54)(58) may include a gain optical fiber as exemplarily shown in FIG. 4. The gain optical fiber may be, for example, an optical fiber doped with a gain element so that the pulsed laser beam is amplified through stimulated emission from atoms excited by the pump beam.

[0061] Meanwhile, an isolator (31) may be further provided between the pulse beam generator (20) and the optical amplifier (50) to prevent reverse transmission of light from the optical amplifier (50) to the pulse beam generator (20). In addition, when the optical amplifier (50) output terminal, for example, a plurality of optical amplifiers (51) and (55), an isolator (35) may be further provided at the final optical amplifier (55) output terminal to prevent reverse transmission of light from the outside to the laser device (10).

[0062] In Fig. 4, it is illustrated that two amplifier units (51)(55) are provided, but the embodiment is not limited thereto. The amplifier unit (50) may be configured as a single structure or may include three or more amplifier units.

[0063] Fig. 5 shows an example of a laser device (10) according to an embodiment configured to transmit light through an optical fiber (37). Fig. 5 shows an example of a laser device (10) according to an embodiment applying the pulse beam generator (20) of Fig. 3.

[0064] Referring to FIG. 5, a laser device (10) according to an embodiment includes a pulse beam generating unit (20) that generates a shaped pulse laser beam and an optical amplifying unit (50), and light transmission within the laser device (10) can be arranged to be performed through an optical fiber (37).

[0065] The pulse beam generating unit (20) may include a light source unit (30) that generates a pulse laser beam, and a light modulator (40) that shapes the pulse laser beam generated from the light source unit (30). In the present embodiment, the control unit (11) applies a control signal to the light modulator (40), and the light modulator (40) may be controlled to shape the pulse laser beam generated from the light source unit (30) into a shape in which the forward slope based on the peak value is gentle and the backward slope is steeper than the forward slope.

[0066] The light source unit (30) may include a pumping laser element (26) that provides a pump beam, and an optical amplifier unit (25) that amplifies the pump beam provided from the pumping laser element (26). The light source unit (30) may further include a coupler (27) that couples the pump beam onto the path of the optical amplifier unit (25). Here, the pump beam may be a pulse beam, and for example, may be a pulse beam of a Gaussian waveform or an intensity-variable pulse beam.

[0067] The optical amplifier (25) may include a gain medium (28) that amplifies a pump beam provided from a pumping laser element (26). The gain medium (28) may generate an amplified pulse laser beam using the pump beam. The gain medium (28) may include a gain optical fiber as exemplarily shown in FIG. 5. The gain optical fiber may be, for example, an optical fiber doped with a gain element so that beam amplification is achieved through stimulated emission from atoms excited by the pumping beam.

[0068] Meanwhile, the optical amplification unit (25) may further include a pair of optical fiber Bragg gratings (29a) (29b) arranged on both sides of the gain medium (28). The optical fiber Bragg grating (29a) (29b) is, for example, an optical fiber that reacts (transmits, reflects, etc.) only to a specific wavelength in a narrow range that satisfies the Bragg condition, and has a grating structure in which the effective refractive index in the optical fiber core is periodically or aperiodically changed in the direction of the optical fiber axis. By arranging the optical fiber Bragg gratings (29a) (29b) on both sides of the gain medium (28), only the wavelength band that satisfies the Bragg condition can be transmitted and reflected. Since a part of the pulse laser beam is reflected by the optical fiber Bragg gratings (29a) (29b) and re-passes through the gain medium (28), the amplification ratio in the optical amplification unit (50) can be increased. In addition, by providing the optical fiber Bragg gratings (29a) (29b), the wavelength linewidth of the pulse laser beam can be reduced.

[0069] The pump beam provided from the pumping laser element (26) can be amplified in the optical amplifier (25) and transmitted to the optical modulator (40) as a pulse laser beam.

[0070] The optical modulator (40) can be controlled by the control unit (11) to shape the pulse laser beam generated from the light source unit (30) into a shape in which the forward slope is gentle and the backward slope is steeper than the forward slope based on the peak value. Here, the pulse laser beam before shaping can be an intensity-variable pulse beam, for example, a pulse beam with a Gaussian waveform.

[0071] The optical modulator (40) may include, for example, an acoustic optical modulator. During the beam shaping mode, the optical modulator (40), for example, the acoustic optical modulator, may be maintained in an on state. The control signal of the control unit (11) may be provided to the acoustic optical modulator as electrical power, for example, RF power. Pulsed laser beam shaping may be achieved by adjusting the electrical power, for example, RF power, applied to the optical modulator (40), for example, the acoustic optical modulator. As another example, the optical modulator (40) may include a spatial light modulator (SLM). The spatial light modulator may include a silicon substrate, a driving circuit, pixel electrodes, etc., and may adjust the phase of the laser light by adjusting the voltage applied to each pixel electrode, and may modulate the input laser pulse into a desired shape.

[0072] In this way, the shaped pulse laser beam (Ls') generated from the pulse beam generator (20) can be transmitted to the optical amplifier (50) using the optical fiber (37) as a transmission path. The pulse laser beam (Ls) can be amplified and output from the optical amplifier (50).

[0073] FIG. 5 shows an example of a single structure optical amplifier (51) provided as an optical amplifier (50). The optical amplifier (51) may include a gain medium (54) that amplifies a shaped pulse laser beam (Ls') transmitted from a pulse beam generator (20) using a pump beam provided from a pumping laser element (52), and a coupler (53) that couples the pump beam onto the propagation path of the shaped pulse laser beam (Ls'). The gain medium (54) may amplify the pulse laser beam (Ls') using the pump beam on the propagation path of the pulse laser beam (Ls'). As exemplarily shown in FIG. 5, the gain medium (54) may include a gain optical fiber. The gain optical fiber may be, for example, an optical fiber doped with a gain element so that the pulse laser beam (Ls) is amplified through stimulated emission from atoms excited by the pump beam.

[0074] Meanwhile, in FIG. 5, the optical amplification unit (50) is illustrated as having a single structure including an optical amplification unit (51), but the embodiment is not limited thereto. For example, the optical amplification unit (50) may include a plurality of optical amplification units as described above with reference to FIG. 4. In the case where the optical amplification unit (50) includes a plurality of optical amplification units, an isolator may be further provided between the optical amplification units to prevent reverse transmission of light between the optical amplification units as exemplarily shown in FIG. 4.

[0075] Meanwhile, an isolator (31) may be further provided between the pulse beam generator (20) and the optical amplifier (50) to prevent reverse transmission of light from the optical amplifier (50) to the pulse beam generator (20). In addition, when the optical amplifier (50) output terminal, for example, has multiple optical amplifiers, an isolator (35) may be further provided at the final optical amplifier output terminal to prevent reverse transmission of light from the outside to the laser device (10).

[0076] FIGS. 4 and 5 only show examples of a laser device (10) according to an embodiment configured to transmit light through an optical fiber (37), but the embodiment is not limited thereto, and various modifications are possible.

[0077] Again, referring to FIG. 1, the focusing optical system (100) includes one or more lenses (110) and is configured to focus a shaped pulse laser beam (Ls) output from a laser device (10) according to an embodiment onto a processing object (T). The focusing optical system (110) may further include a reflective member (101) that changes an optical path of the pulse laser beam (Ls). The reflective member (101) may be a reflective mirror or a total reflection prism. The processing object (T) is mounted on a stage (3) and can move as the position of the stage (3) is controlled by a stage position control unit (5).

[0078] The laser processing device (1) can perform a processing process, for example, a cutting process, by irradiating a shaped pulse laser beam (Ls) output from the laser device (10) according to the various embodiments described above onto a processing target (T).

[0079] The laser processing device (1) according to the embodiment can be implemented to perform a cutting process, for example, in a stealth dicing manner. For example, the laser processing device (1) according to the embodiment can be used as a semiconductor post-process, by focusing a shaped pulse laser beam (Ls) obtained from a laser device (10) onto a processing target (T), for example, a semiconductor wafer, to form a modified region, and cutting the semiconductor wafer by cracks generated from the modified region. In addition, the laser device according to the embodiment can be applied to various types of laser processing devices that require improved processing performance.

[0080] FIGS. 6A and 6B show waveforms of a pulsed laser beam formed by a laser device (10) according to an embodiment (waveforms of an embodiment). FIG. 6A shows a measured waveform, and FIG. 6B shows the relationship between the forward width and the backward width of the waveform shown in FIG. 6A. The shaped pulsed laser beam obtained by the laser device (10) according to the embodiment is formed as a waveform in which the forward slope relative to the peak (P) is gentle, and the backward slope is steeper than the forward slope. As in FIG. 6B, when the pulse width of the pulsed laser beam is Tp, the forward width reaching the peak is T1, and the backward width thereafter is T2, the shaped pulsed laser beam obtained by the laser device (10) according to the embodiment satisfies the condition of T1 > T2 (wherein, Tp = T1 + T2). At this time, the ratio of T1 to Tp (T1 / Tp) may be 0.7 or more. For example, T1 / Tp may be about 0.7 to 0.9, about 0.7 to 0.85, or about 0.8 to 0.9. Here, the pulse width of the pulsed laser beam described in FIG. 6b and below may represent, for example, the full width at half maximum.

[0081] Figures 7a and 7b show the waveform of a Gaussian pulse laser beam corresponding to the basic waveform (waveform of Comparative Example 1). Figure 7a shows the measured waveform, and Figure 7b shows the relationship between the front width and the rear width of the waveform shown in Figure 7a.

[0082] The Gaussian pulse laser beam of Comparative Example 1 is formed into a waveform having the same forward slope and backward slope relative to the peak (P). As in Fig. 7b, when the pulse width of the Gaussian pulse laser beam is Tp', the forward width reaching the peak (P) is T1', and the backward width thereafter is T2', the Gaussian pulse laser beam satisfies the condition of T1' = T2' (where, Tp' = T1' + T2').

[0083] Figures 8a and 8b show the waveform of the pulsed laser beam of Comparative Example 2 (waveform of Comparative Example 2). Figure 8a shows the measured waveform, and Figure 8b shows the relationship between the forward width and the backward width of the waveform shown in Figure 8a. The pulsed laser beam of Comparative Example 2 is formed as a waveform in which the forward slope based on the peak (P) is steep and the backward slope is gentler than the forward slope. As in Figure 8b, when the pulse width of the pulsed laser beam of Comparative Example 2 is Tp”, the forward width reaching the peak (P) is T1”, and the backward width thereafter is T2”, the pulsed laser beam of Comparative Example 2 satisfies the condition of T1” < T2” (wherein, Tp” = T1” + T2”).

[0084] Hereinafter, the processing performance when applying the laser device (10) according to the embodiment will be described with reference to FIGS. 9 to 17c. The waveform of the embodiment applied to the processing performance evaluation has a shape in which the forward slope based on the peak (P) is gentle, and the backward slope is steeper than the forward slope, as shown in FIGS. 6a and 6b. The waveform of the embodiment has a pulse rising time longer than the pulse falling time. The waveform of Comparative Example 1 applied for comparison has a Gaussian shape, as shown in FIGS. 7a and 7b, and the pulse rising time and falling time are the same. In addition, the waveform of Comparative Example 2 applied for comparison has a shape in which the forward slope based on the peak (P) is steep, the backward slope is gentler than the forward slope, and the pulse falling time is longer than the pulse rising time, as shown in FIGS. 8a and 8b.

[0085] FIGS. 9 to 11 are graphs showing the results of evaluating the amount of cracks according to the power (unit: W) and defocus of the pulsed laser beam of Examples, Comparative Examples 1 and 2. FIG. 9 shows the change in crack length of the processed sample according to the pulsed laser beam power when the pulsed laser beam is focused to a Defocus state of -0.110 mm. FIG. 10 shows the change in crack length of the processed sample according to the pulsed laser beam power when the pulsed laser beam is focused to a Defocus state of -0.115 mm. FIG. 11 shows the change in crack length of the processed sample according to the pulsed laser beam power when the pulsed laser beam is focused to a Defocus state of -0.120 mm. In FIGS. 9 to 11, the horizontal axis represents the processing power of the pulsed laser beam (unit: W), and the vertical axis represents the crack length (unit: μm).

[0086] Looking at FIGS. 9 to 11, when the power of the pulse laser beam is 2 W or less, the crack length does not differ significantly between the waveform of the example and the waveform of Comparative Example 1, but in the high-power section of 2 W or more, it can be confirmed that the crack length in the waveform of the example is longer than that in the waveform of Comparative Example 1 and Comparative Example 2 in all defocuses. In addition, it can be seen that in the waveform of the example, in the high-power section of 2 W or more, the crack length is longest when the defocus is -0.115 mm.

[0087] Therefore, as can be seen from FIGS. 9 to 11, when a cutting process is performed with an appropriate output power, for example, 2 W to 4 W, using a laser processing device (1) that applies a laser device (10) according to an embodiment, a crack length can be generated longer when a pulsed laser beam is irradiated once, so that the number of times the pulsed laser beam is irradiated repeatedly can be reduced during a semiconductor wafer or chip dicing process, thereby shortening the processing time.

[0088] Fig. 12 shows a comparison of the length of a crack according to the pulse width and pulse rise time of a shaped pulse laser beam (example waveform) formed by a laser device (10) according to an embodiment. In Fig. 12, the horizontal axis represents the pulse rise time (unit: ns), and the vertical axis represents the bottom uniform (crack) length (unit: μm). Here, the bottom represents the side opposite to the surface on which semiconductor elements are formed on the wafer. When dicing a wafer into chip units or predetermined block units, the cutting process can be performed on the bottom of the wafer.

[0089] The graph in Fig. 12 shows the relationship between the rise time of the pulse and the uniform length when the pulse widths of the example waveforms are about 360 ns, about 400 ns, about 430 ns, about 460 ns, and about 500 ns, respectively. Gaussian corresponds to the basic waveform (Comparative Example 1) and represents the crack length for a Gaussian waveform pulse with a pulse width of about 320 ns. The length of the crack that occurs when irradiated once is about 62.7 μm.

[0090] Looking at Fig. 12, it can be seen that the pulse width of the example waveform that can make the crack length longer than the basic waveform is larger than the pulse width of the basic waveform. In addition, when the pulse width is approximately 400 ns or more, the crack length by the example waveform becomes almost longer than that by the basic waveform with a pulse width of 320 ns, and it can be seen that the crack length also increases as the pulse width increases. Fig. 12 shows an example where the crack length is the longest when the pulse width is 500 ns and the pulse rise time is 300 ns to 380 ns.

[0091] Therefore, the laser device (10) according to the embodiment can set the pulse width to secure a desired crack length when irradiating the pulse laser beam once. In addition, when a cutting process is performed with a pulse laser beam having the pulse width set in this way and having a forward slope that is gentler than a backward slope based on the peak (P), the crack length can be generated longer when the pulse laser beam is irradiated once, so that the number of times the pulse laser beam is irradiated repeatedly can be reduced during a semiconductor wafer or chip dicing process, thereby shortening the processing time.

[0092] Figures 13 to 15 are graphs showing the results of evaluating the scattered beam according to defocus when the pulse laser beam has a high power of 2 W or more. Figures 13 to 15 show the relationship between the crack length and the scattered beam according to defocus when the pulse laser beam has high powers of 2.4 W, 2.8 W, and 3.0 W, respectively. As can be seen in Figures 13 to 15, at a high power of 2 W or more, even though the crack length increases, there is almost no difference in the scattered beam between the basic waveform (Comparative Example 1) and the exemplary waveform, and it can be seen that the scattered beam characteristics of the exemplary waveform are superior to those of the basic waveform (Comparative Example 1) at high power. The crack length is the longest at a defocus of -0.105 mm, but it can be confirmed that the scattered beam exhibits the best characteristics at a defocus of -0.115 mm for the exemplary waveform.

[0093] FIGS. 16a to 16c are graphs showing the BHC (Backside half cut) generation height at each frequency of 100 kHz, 120 kHz, and 140 kHz when applying a pulse laser beam of a basic waveform (Comparative Example 1), and FIGS. 17a to 17c are graphs showing the BHC generation height at each frequency of 100 kHz, 120 kHz, and 140 kHz when applying a pulse laser beam of an example waveform.

[0094] Comparing the graphs of FIGS. 16a to 16c with the graphs of FIGS. 17a to 17c, it can be confirmed that the BHC generation height by frequency is also superior for the exemplary waveform compared to the basic waveform (Comparative Example 1). As described above, the laser device (10) according to the exemplary embodiment generates a pulsed laser beam having a gentle forward slope relative to the peak (P) and a steeper backward slope than the forward slope compared to the basic waveform, which is a Gaussian waveform. Therefore, when the pulsed laser beam is irradiated once, a crack length can be generated longer than when the basic waveform is applied, so that the wafer cutting force and processing speed can be improved, and thus the yield can be improved.

[0095] As described above, the laser device (10) according to the embodiment generates a pulse laser beam shaped into a shape in which the reference forward slope is gentle and the rear slope is steeper than the forward slope, so that when the pulse laser beam is irradiated once, a uniform length can be generated, so that the cutting power is improved and the processing time can be shortened.

[0096] Although the above-described laser device and the laser processing device including the same have been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible from the above. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of this specification is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being included.

Claims

1. A pulse beam generator for generating a shaped pulse laser beam; A first optical amplifier that amplifies a pulse laser beam generated from the pulse beam generator; A laser device comprising a control unit that controls the pulse beam generating unit to generate the pulse laser beam shaped into a shape in which the forward slope of the pulse laser beam is gentle and the backward slope is steeper than the forward slope with respect to the peak of the pulse laser beam.

2. In the first paragraph, when the pulse width of the pulse laser beam is Tp, the front width reaching the peak is T1, and the rear width thereafter is T2, The above pulse laser beam is a laser device that satisfies the condition of T1 > T2 (wherein, Tp = T1 + T2).

3. A laser device in the second paragraph, wherein the ratio of T1 to Tp (T1 / Tp) is 0.7 or more.

4. In the first paragraph, the pulse beam generating unit, A laser device comprising a laser element that generates a pulsed laser beam, A laser device configured to generate the pulse laser beam formed from the laser element by applying a control signal from the control unit.

5. In the first paragraph, the pulse beam generating unit, A light source unit that generates a pulsed laser beam; It includes a light modulator that shapes a pulse laser beam generated from the above light source unit; A laser device in which a control signal is applied from the control unit to the optical modulator, thereby shaping a pulse laser beam generated from the light source unit in the optical modulator.

6. In the fifth paragraph, the light source unit, A laser device comprising a laser element that generates a pulsed laser beam.

7. In paragraph 5, the light source unit, A pumping laser element providing a pump beam; A laser device comprising a second optical amplifier having a gain medium that amplifies the pump beam to generate the pulse laser beam.

8. In the 7th paragraph, the light source unit, A laser device further comprising a coupler that couples the pump beam onto the path of the second optical amplifier.

9. A laser device according to claim 7, wherein the gain medium includes a gain optical fiber.

10. A laser device according to claim 9, wherein the second optical amplifier further comprises a pair of optical fiber Bragg gratings arranged on both sides of the gain optical fiber.

11. A laser device in which light transmission within the pulse beam generating unit in the fifth paragraph is performed via an optical fiber.

12. A laser device according to claim 1, further comprising a first isolator between the pulse beam generator and the first optical amplifier.

13. In the first paragraph, the first optical amplification unit, A gain medium that amplifies the pulsed laser beam with a pump beam provided from a pumping laser device; and A laser device comprising a coupler that couples the pump beam onto the path of the pulse laser beam.

14. A laser device according to claim 13, wherein the gain medium includes a gain optical fiber.

15. A laser device according to claim 13, wherein the first optical amplification unit includes a plurality of optical amplification units.

16. A laser device according to claim 15, further comprising a second isolator between the plurality of optical amplifiers and at least one of the output terminals of the final optical amplifier.

17. In the 13th paragraph, the first optical amplification unit, A laser device further comprising a second isolator at the output terminal.

18. A laser device in which light transmission within the first optical amplification unit is performed via an optical fiber in the 13th paragraph.

19. A laser device according to any one of claims 1 to 18; A laser processing device including a focusing optical system that focuses a shaped pulse laser beam provided from the laser device onto a processing target.

20. In the 19th paragraph, a stage on which the processing object is placed; and, A laser processing device further comprising a stage position control unit for controlling the position of the stage.

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