TWI910605B - Laser processing apparatus - Google Patents

Abstract

A laser processing apparatus is disclosed. The disclosed laser processing apparatus includes: a laser source for generating laser light; a spatial light modulator for modulating the laser light provided from the laser source to form a processing modulation pattern; a focusing optical system for focusing the laser light modulated in the spatial light modulator onto a processing object; a relay lens optical system located between the spatial light modulator and the focusing optical system; and a control unit for controlling the spatial light modulator to modulate the laser light according to the processing modulation pattern. The relay lens optical system is configured to transmit an image of the processing modulation pattern formed by the spatial light modulator to the entrance pupil of the focusing optical system, and includes a first lens group, a second lens group, and a field lens located between the first lens group and the second lens group.

Description

Laser processing equipment

This invention relates to a laser processing apparatus that includes a relay lens optical system.

Laser processing refers to the process of irradiating the surface of an object with laser light to treat the shape or physical properties of the object's surface. In order to perform laser processing, the laser light emitted from the laser source is focused on a specified area of the object to be processed.

Laser processing equipment can perform high-precision processing in a non-contact manner, regardless of the material of the object being processed. Because it uses focused laser light to form spots for processing, the thermal stability of the object being processed is ensured, and ultra-precision processing can be performed without being limited by the size of the processing area.

The size of such a laser processing apparatus can be determined by the optical system used to perform the laser processing. Therefore, a miniaturized optical system design is needed to realize the laser processing apparatus.

Technical issues

A laser processing apparatus is provided, comprising a relay lens optical system designed in a resizable manner.

Methods for solving problems

A laser processing apparatus of one type includes: a laser light source for generating laser light; a spatial light modulator for modulating the laser light provided from the laser light source to form a processing modulation pattern; a focusing optical system for focusing the laser light modulated in the spatial light modulator onto a processing object; a relay lens optical system located between the spatial light modulator and the focusing optical system, configured to transmit an image of the processing modulation pattern formed by the spatial light modulator to the entrance pupil of the focusing optical system, and including a first lens group, a second lens group, and a field lens located between the first lens group and the second lens group; and a control unit for controlling the spatial light modulator to modulate the laser light according to the processing modulation pattern.

The first lens group and the second lens group may each include two or more lenses.

The first lens group and the second lens group respectively include a first lens with positive refractive power and a second lens with negative refractive power, and the field lens can be configured to have positive refractive power.

The relay lens optical system can be configured in the form of 3F lens units.

The spatial light modulator can form the processing modulation pattern under the control of the control unit, so that the laser light modulated according to the processing modulation pattern is focused by the focusing optical system at multiple focusing points at different depths within the processed object.

Laser light modulated according to the modulation pattern described above may contain light components with different refractive intensities relative to the basic light components.

The spatial light modulator may include a reflective spatial light modulator.

It further includes optical components. When the direction of travel of the laser light incident on the optical component from the laser light source side is referred to as the first direction of travel, the optical component may be a prism structure. The prism structure is configured to cause the laser light to be incident obliquely on the spatial light modulator and to cause the laser light modulated and reflected in the spatial light modulator to travel in a direction parallel to the first direction of travel, and the internal reflecting surface is parallel to the spatial light modulator.

The focusing optical system may include an objective lens that focuses the incident laser light onto the object being processed.

The focusing optical system may further include a beam expander, configured between the relay lens optical system and the objective lens, to expand the beamwidth of the laser light.

It further includes a reflector located between the relay lens optical system and the objective lens, and the beam expander can be disposed between the relay lens optical system and the reflector or between the reflector and the objective lens.

It may further include: a stage, configured to be capable of two-dimensional planar movement; and a stage position control unit for controlling the two-dimensional planar movement of the stage.

A laser processing apparatus of one type may include: a laser source for generating laser light; a reflective spatial light modulator for modulating the laser light provided from the laser source to form a processing modulation pattern; a focusing optical system for focusing the laser light modulated in the reflective spatial light modulator onto a processing object, and including an objective lens; and a relay lens optical system located between the reflective spatial light modulator and the focusing optical system, configured to allow the laser light modulated in the reflective spatial light modulator to pass through the processing object. The image of the processed modulation pattern formed by the spatial light modulator is transmitted to the entrance pupil of the focusing optical system, and includes a first lens group, a second lens group, and a field lens located between the first lens group and the second lens group; a stage configured to be movable in a two-dimensional plane; a stage position control unit for controlling the two-dimensional plane movement of the stage; and a control unit for controlling the spatial light modulator to modulate the laser light according to the processed modulation pattern.

The first lens group and the second lens group may each include two or more lenses.

The first lens group and the second lens group may respectively include a first lens with positive refractive power and a second lens with negative refractive power, and the field lens may be configured to have positive refractive power.

The relay lens optical system can be configured in the form of 3F lens units.

The spatial light modulator can form the processing modulation pattern under the control of the control unit, so that the laser light modulated according to the processing modulation pattern is focused by the focusing optical system at multiple focusing points at different depths within the processed object.

Laser light modulated according to the modulation pattern described above may contain light components with different refractive intensities relative to the basic light components.

It further includes a reflector located between the relay lens optical system and the objective lens, and the focusing optical system may further include a beam expander configured between the relay lens optical system and the reflector or between the reflector and the objective lens to amplify the beamwidth of the laser light.

It further includes an optical component, which may be a prism structure in which, when the direction of travel of the laser light incident on the optical component from the laser light source side is referred to as the first direction of travel, it is configured to cause the laser light to be incident obliquely on the spatial light modulator and to cause the laser light modulated and reflected in the spatial light modulator to travel in a direction parallel to the first direction of travel, and the internal reflecting surface is parallel to the spatial light modulator.

The effect of the invention

According to the laser processing apparatus of the embodiment, miniaturization of the apparatus is achieved because the relay lens optical system used for light transmission between the laser light source and the focusing optical system can be reduced in size. In addition, the number of lenses in the relay lens optical system can also be reduced, thereby enabling a laser processing apparatus that includes a reduction in the length of the optical system and an optical system composed of fewer lenses.

The following description provides a detailed explanation of illustrative embodiments with reference to the accompanying drawings. In the following figures, the same reference numerals refer to the same constituent elements, and the sizes of the constituent elements in the figures may be exaggerated for clarity and convenience of explanation. On the other hand, the embodiments described below are merely illustrative and various modifications can be made from such embodiments.

Hereinafter, the expressions "upper" or "above" may include not only situations where the object is directly located in contact with the object above, below, left, or right, but also situations where the object is located in a non-contact manner above, below, left, or right. Unless the context clearly indicates otherwise, the singular expression includes the plural expression. Furthermore, when a part "includes" a constituent element, unless otherwise specifically stated to the contrary, this meaning may include other constituent elements rather than exclude them.

The use of the term "described" and similar descriptive terms may correspond to both the singular and the plural. As for the steps constituting a method, in the absence of an explicit description of the order or a contrary description, the steps may be performed in an appropriate order, and are not necessarily limited to the order described.

In addition, the terms "...part" and "module" used in the instruction manual refer to a unit that processes at least one function or action, which can be implemented by hardware or software or by a combination of hardware and software.

The lines connecting or connecting components between the constituent elements shown in the diagram illustratively represent functional and/or physical or electrical connections, and may be represented in an actual device as various alternative or additional functional, physical or electrical connections.

All examples or illustrative terms are used only to illustrate the technical ideas in detail, and are not intended to limit the scope of the claims.

The laser processing apparatus according to the embodiments described below with reference to the drawings can be applied to a stealth dicing laser processing apparatus, for example, in a dicing process included in semiconductor post-processing, where laser light is focused inside a semiconductor wafer to form a modified region, and the semiconductor wafer is diced due to cracks generated from the modified region.

Figure 1 schematically shows the laser processing apparatus 100 according to an embodiment. Figure 2 is a plan view that simply shows the exemplary configuration of the processing object 1 of Figure 1.

Referring to FIG1, the laser processing apparatus 100 includes: a laser light source 10 for generating laser light; a spatial light modulator 30 for modulating the laser light provided from the laser light source 10 to form a processing modulation pattern; a focusing optical system 60 for focusing the laser light modulated in the spatial light modulator 30 according to the processing modulation pattern on the processing object 1; a relay lens optical system 50 for transmitting the image of the processing modulation pattern formed by the spatial light modulator 30 to the entrance pupil of the focusing optical system 60; and a control unit 20 for controlling the spatial light modulator 30 to modulate the laser light according to the processing modulation pattern. The laser processing apparatus 100 is configured such that the control unit 20 controls not only the spatial light modulator 30 but also the laser light source 10, or it may be configured such that the laser light source 10 is controlled by a separate control unit. Figure 1 shows an example in which the control unit 20 controls both the spatial light modulator 30 and the laser light source 10. On the other hand, the laser processing apparatus 100 may further include: a stage 3 for moving the object 1 placed on the mounting surface of the support stage 5; and a stage position control unit 70 for controlling the position of the stage 3. In addition, the laser processing apparatus 100 may further include an optical system position control unit (not shown) that adjusts the relative distance between the focusing optical system 60 and the object 1 to adjust the position of the focusing point of the laser light inside the object 1. According to this embodiment, the laser processing apparatus 100 can irradiate the processing object 1 with laser light modulated by the spatial light modulator 30 according to the processing modulation pattern to perform processing processes such as cutting.

The object to be processed 1 may include, for example, a semiconductor wafer. The object to be processed 1 may include a semiconductor wafer made of silicon semiconductor material or a semiconductor wafer made of other materials. For example, referring to FIG2, the object to be processed 1 may include a semiconductor wafer with multiple functional elements 2 arranged in a two-dimensional arrangement on its upper part. However, it is not limited to this; the semiconductor wafer included in the object to be processed may not be equipped with multiple functional elements 2. The object to be processed 1 is not limited to a semiconductor wafer and may be made of various materials.

The multiple functional elements 2 may include any of the following: light-receiving elements such as photodiodes, light-emitting elements such as laserdiodes, circuit elements such as logic elements or memory elements. However, they are not limited to this; the multiple functional elements 2 may include various types of elements other than those described above. Using the laser processing apparatus 100 according to the embodiment, the object 1 can be cut along a predetermined cutting line L that divides the area equipped with the multiple functional elements 2. The predetermined cutting line L may include a structure in which multiple first lines extending in a first direction and arranged parallel to each other in a second direction perpendicular to the first direction, and multiple second lines extending in the second direction and arranged parallel to each other in the first direction intersect each other. In this case, the first direction and the second direction may be perpendicular to each other. However, they are not limited to this; the first direction and the second direction may also not be perpendicular to each other.

The laser source 10 can emit pulsed laser light that is transmissive to the object being processed 1. Furthermore, when the laser light is focused inside the object being processed 1, the laser source 10 can emit pulsed laser light that exhibits conditions for multiphoton absorption within the object being processed 1. The conditions for multiphoton absorption are well-known in the field of stealth dicing technology, and therefore, their description is omitted here.

The spatial light modulator (SLM) 30 can spatially modulate laser light incident from the side of the laser source 10 to form a processing modulation pattern. The control unit 20 can control the spatial light modulator 30 to modulate the laser light according to the set processing modulation pattern. According to the control unit 20, the laser light modulated according to the processing modulation pattern in the spatial light modulator 30 can be focused by the focusing optical system 60 at multiple focusing points at different depths inside the processing object 1.

The control unit 20 can control the spatial light modulator 30 to form a preset processing modulation pattern. In addition, the control unit 20 can control the spatial light modulator 30 according to the processing object 1 and/or according to the processing direction to adjust the processing modulation pattern, thereby adjusting the focal point position of the laser light.

Spatial light modulator 30 may include a reflective spatial light modulator. As another example, spatial light modulator 30 may also include a transmissive spatial light modulator. In FIG1 and FIG7 and FIG8 described below, spatial light modulator 30 is illustrated and illustrated using a reflective spatial light modulator as an example, but is not limited thereto.

The spatial light modulator 30 can be configured to control light at the pixel level or sub-pixel level. The spatial light modulator 30 may include, for example, a reflective liquid crystal on silicon (LCOS) spatial light modulator to reflect and output incident laser light, and modulate the laser light according to a processing modulation pattern under the control of the control unit 20. The reflective liquid crystal spatial light modulator changes the alignment direction of liquid crystal molecules based on the electric field formed by each pixel or sub-pixel in the liquid crystal layer; therefore, the phase of the laser light passing through the liquid crystal layer also differs from pixel to pixel. This phase modulation allows the formation of a processing modulation pattern.

As another example, the spatial light modulator 30 may include a digital light processing (DLP) type spatial light modulator, which includes a two-dimensional arrangement of digital mirror devices (DMDs) to enable light control at the pixel level or sub-pixel level. The DLP type spatial light modulator can turn light on/off at the pixel level or sub-pixel level, or adjust the direction of travel of reflected light and the resulting divergence angle in different ways to form a processing modulation pattern.

The spatial light modulator 30 can form a processing modulation pattern so that laser light modulated according to the processing modulation pattern can be focused at multiple focal points at different depths within the processing object 1. At this time, the laser light modulated according to the processing modulation pattern may contain light components with different refractive intensities relative to the basic light component. The light components with different refractive intensities are light components that defocus the basic light component and may correspond to light components with negative and/or positive refractive intensities. The basic light component represents the light component whose refractive intensities are not adjusted by the spatial light modulator 30, while the defocused light component may represent the light component whose refractive intensities are adjusted by the spatial light modulator 30. The focal point of the light components with different refractive intensities can be located before or after the focal point of the basic light component.

As an example, the spatial light modulator 30 can be controlled by the control unit 20 so that the laser light modulated according to the processing modulation pattern includes a basic light component and a light component with a different refractive power. The light component with a different refractive power can be a light component representing positive or negative refractive power. In this case, in FIG3, one of the first focusing point P1 and the second focusing point P2 is, for example, the focusing point of the basic light component, while the other can be the focusing point of the light component that is defocused in a manner that displays negative or positive refractive power relative to the basic light component.

As another example, the spatial light modulator 30 can be controlled by the control unit 20 so that the laser light modulated according to the processing modulation pattern includes light components that are focused in a manner exhibiting positive refractive power and light components that are focused in a manner exhibiting negative refractive power. In this case, one of the first focusing point P1 and the second focusing point P2 in FIG3 is, for example, a focusing point for light components that are focused in a manner exhibiting negative refractive power, while the other can be a focusing point for light components that are focused in a manner exhibiting positive refractive power.

As another example, the spatial light modulator 30 can also be controlled by the control unit 20 to form a processing modulation pattern that focuses the laser light at three or more focal points at different depths within the processing object 1. In this case, the laser light modulated according to the processing modulation pattern can be focused by the focusing optical system 60 at three or more focal points at different depths within the processing object 1. For example, the focal point at the middle depth among the three focal points can be the focal point of the basic light component, the focal point at the first depth can be, for example, the focal point of the light component that is defocused relative to the basic light component in a manner exhibiting positive refractive power, and the focal point at the third depth can be, for example, the focal point of the light component that is defocused relative to the basic light component in a manner exhibiting negative refractive power.

Figure 3 shows an example of using a focusing optical system 60 to focus laser light modulated by a spatial light modulator 30 according to a set processing modulation pattern at multiple focusing points inside the processing object 1.

Referring to Figure 3, when laser light modulated according to a set processing modulation pattern is focused by the focusing optical system 60 onto the object being processed 1, the modulated laser light can be focused at multiple focusing points at different depths, such as a first focusing point P1 and a second focusing point P2. At these multiple focusing points, such as the first focusing point P1 and the second focusing point P2, the laser light can be absorbed to form a first modified region 4a and a second modified region 4b, respectively. Figure 3 shows an example where the first focusing point P1 is positioned at a first depth d1 from the upper surface 1a of the object being processed, and the second focusing point P2 is positioned at a second depth d2 from the upper surface 1a of the object being processed. In this case, the first depth d1 and the second depth d2 are different from each other. As illustrated in Figure 3, laser light modulated by the spatial light modulator 30 according to the processing modulation pattern can be focused by the focusing optical system 60 at a first focusing point P1 at a first depth d1 from the upper surface 1a of the object being processed and a second focusing point P2 at a second depth d2 from the upper surface 1a of the object being processed. This allows the formation of a first modified region 4a and a second modified region 4b at the first focusing point P1 and the second focusing point P2, respectively. By moving the object being processed, arrangements of the first modified region 4a and the second modified region 4b can be formed at the first depth d1 and the second depth d2, respectively. In Figure 3 and the following description, the cases where the first modified region 4a and the second modified region 4b are formed at positions of the first focusing point P1 and the second focusing point P2 at different depths d1 and d2 are explained and illustrated, but the description is not limited to this. The number of focal points at different depths and the number of corresponding modified regions can be three or more.

As described above, the spatial light modulator 30 can form a processing modulation pattern so that the laser light can be focused at multiple focal points at different depths within the processing object 1. At this time, the laser light modulated according to the processing modulation pattern can contain light components with different refractive intensities relative to the basic light components.

On the other hand, when the laser light modulated by the spatial light modulator 30, which forms a processing modulation pattern, is focused inside the object 1 using the focusing optical system 60, modified regions can be formed at multiple focusing points at different depths of the focused laser light. As the object 1 moves, modified regions can be formed discontinuously along the predetermined cutting line L, thus forming an arrangement of multiple modified regions at different depths along the predetermined cutting line L. The arrangement of multiple modified regions can form a cutting line.

For example, during laser irradiation for one duty cycle to form the modified regions, a first modified region 4a and a second modified region 4b can be formed within the object being processed at positions of a first focal point P1 and a second focal point P2 at a first depth d1 and a second depth d2, respectively. When the laser light irradiates a predetermined cutting line L, if the object being processed is moved along the predetermined cutting line L, an arrangement of the first modified regions 4a and an arrangement of the second modified regions 4b can be formed at positions corresponding to the predetermined cutting line L at the first depth d1 and the second depth d2, respectively. Here, one duty cycle is the time required to irradiate laser light at one position to form the first modified regions 4a and the second modified regions 4b. During one duty cycle, the laser light can irradiate once or multiple times in a pulsed pattern. Furthermore, in the arrangement of the first modified regions 4a and the second modified regions 4b, the interval between the modified regions can be determined by the moving speed of the object 1 and the duty cycle interval of the pulsed laser light. Since the first modified regions 4a and the second modified regions 4b, which are discontinuously arranged along the predetermined cutting line L, generate cracks during the cooling process, the moving speed of the object 1 and the duty cycle interval of the pulsed laser light can determine the interval at which the object 1 can be cut along the predetermined cutting line L. The cracks generated during the cooling process in the first modified regions 4a and the second modified regions 4b, which are adjacent to each other in the depth direction, can intersect.

On the other hand, during a duty cycle, the first remodeling region 4a and the second remodeling region 4b, which are adjacent to each other in the depth direction, can exist in a state of separation from each other, or they can merge in the depth direction to form an enlarged remodeling region.

When the first modified region 4a and the second modified region 4b, which are adjacent in the depth direction, are separated from each other, the arrangement of the first modified region 4a and the arrangement of the second modified region 4b can respectively form cutting lines. In this case, during one processing step along the predetermined cutting line L, cutting lines can be formed simultaneously at the first depth d1 and the second depth d2 of the object 1, thereby reducing the number of times the cutting process is repeated to sequentially form multiple cutting lines at different depths, and thus shortening the cutting process time.

Alternatively, as another example, the first modified region 4a and the second modified region 4b, which are adjacent to each other in the depth direction, can also be merged to form an enlarged modified region (4' in Figure 4). In this case, the arrangement of the first modified region 4a and the arrangement of the second modified region 4b also form an arrangement of enlarged modified regions in the depth direction, thereby forming a cutting line in which the enlarged modified regions are discontinuously arranged along the predetermined cutting line L. In this case, during one processing step along the predetermined cutting line L, multiple cutting lines are sequentially formed at different depths by repeatedly performing the cutting process. This allows the formation of a cutting line including the arrangement of enlarged modified regions within the processed object 1, thereby shortening the cutting process time.

Therefore, according to the laser processing apparatus 100 of the embodiment, by using a spatial light modulator 30 to modulate the laser light to form a processing modulation pattern, multiple cutting lines or a single cutting line formed by the arrangement of enlarged modified regions can be formed simultaneously at different depths inside the processed object 1 during a single cutting process along the predetermined cutting line L. This reduces the number of times the cutting process is repeated and shortens the cutting process time.

Figure 4 is used to illustrate the principle of crack c1 being generated inside the treated object 1 in Figure 3. In Figure 4, reference symbol 4' is a dashed line representing the expanded modified region when the first modified region 4a and the second modified region 4b are connected to each other.

Referring to Figure 4, cracks c1 can be generated starting from either the first modified region 4a or the second modified region 4b, or from the expanded modified region 4' formed by connecting the first and second modified regions 4a and 4b. Cracks c1 can be generated during the cooling process of the modified regions heated by laser treatment. Multiple cracks c1 can extend to the upper surface 1a and lower surface 1b of the object being treated 1. However, this is not a limitation; cracks c1 may also extend when external stress is applied to the modified regions. The object being treated 1 can be cut using multiple cracks c1 as a reference.

On the other hand, according to the embodiment of the laser processing apparatus 100, the processing process can be performed more than twice along the predetermined cutting line L while forming different depths of the modified regions, so as to generate cracks sufficient for cutting the object 1. For example, when laser processing is performed simultaneously by changing the interval between the focusing optical system 60 and the object 1 by the optical system position control unit, the position of the cutting line formed inside the object 1 in the optical axis direction (Z direction) can be changed. At this time, each cutting line may include, for example, multiple cutting lines formed by the arrangement of multiple modified regions 4a, 4b formed simultaneously as described with reference to FIG. 3, or cutting lines formed by the arrangement of enlarged modified regions 4' as described with reference to FIG. 4. For example, when two cutting lines are formed during a single processing step as shown in Figure 3, if two processing steps are performed, four cutting lines can be formed at different positions along the optical axis (Z direction) within the processed object 1. Furthermore, when cutting lines are formed by arranging enlarged modified regions 4' as shown in Figure 4, if two processing steps are performed, two processing lines with spans and widths can be formed at different positions along the optical axis (Z direction) within the processed object 1.

Referring again to Figure 1, in the laser processing apparatus 100 of the embodiment, the relay lens optical system 50 can transmit laser light modulated by the spatial light modulator 30 according to the processed modulation pattern to the focusing optical system 60. The relay lens optical system 50 can be configured to transmit the image of the processed modulation pattern formed by the spatial light modulator 30 to the entrance pupil of the focusing optical system 60. For this purpose, the relay lens optical system 50 can be located between the spatial light modulator 30 and the focusing optical system 60.

The relay lens optical system 50 includes a first lens group 51, a second lens group 56, and a field lens 55 located between the first lens group 51 and the second lens group 56. It can be configured to form an imaging relationship between the processing modulation pattern forming surface of the spatial light modulator 30 and the entrance pupil of the focusing optical system 60.

According to the relay lens optical system 50 of the embodiment, the first lens group 51 and the second lens group 56 may each include two or more lenses. For example, the first lens group 51 and the second lens group 56 may each include a lens with positive refractive power and a lens with negative refractive power. In addition, the relay lens optical system 50 may be configured in a manner such as a 3F lens system.

Figure 5 schematically shows an embodiment of the relay lens optical system 50 of Figure 1.

Referring to Figure 5, the relay lens optical system 50 can be configured such that the first lens group 51 and the second lens group 56 each include two lenses, and the field lens 55 includes, for example, one lens. The first lens group 51 can be composed of two lenses, including, for example, a first lens 52 with positive refractive power and a second lens 53 with negative refractive power. The field lens 55 can be configured, for example, to have positive refractive power. The second lens group 56 can be composed of two lenses, including, for example, a first lens 57 with positive refractive power and a second lens 58 with negative refractive power.

As illustrated in Figure 5, the relay lens optical system 50 can form a 3f lens system by placing a field lens 55 between the first lens group 51 and the second lens group 56.

For example, the relay lens optical system 50 can be designed as follows: the focal length of the first lens group 51 is _f1 and the focal length of the second lens group 56 is _f2 , and the distance between the center of the first lens group 51 and the center of the second lens group 56 is _f1 + _f2 , so that the field lens 55 is located at a distance of _f1 from the center of the first lens group 51 and _f2 from the center of the second lens group 56. In this case, the distance from the object surface S1, such as the processing modulation pattern forming surface S1 of the spatial light modulator 30, to the center of the first lens group 51 is f _1/2 , and the distance from the center of the second lens group 56 to the upper surface S2, such as the entrance pupil S2 of the focusing optical system 60, can be f _2/2 . Therefore, the intermediate lens optical system 50 can form a 3f lens unit system.

As described above, by utilizing a field lens 55 arranged between the first lens group 51 and the second lens group 56 to construct a relay lens optical system 50, a 3f lens unit system can be formed. Therefore, the optical path length from the processing modulation pattern forming surface S1 of the spatial light modulator 30 to the entrance pupil S2 of the focusing optical system 60 can be reduced, the optical system of the laser processing apparatus 100 can be reduced, and the overall size of the laser processing apparatus 100 can be reduced. Here, the processing modulation pattern forming surface S1 can correspond to a surface including, for example, the entrance/exit surface 30a of the spatial light modulator 30 or any point within the thickness range of the spatial light modulator 30.

Figure 6a illustrates the reduction effect of the optical path length of the relay lens optical system 50 according to the embodiment. Figure 6b shows the optical path length of the comparative example relay lens optical system 50', and illustrates the case where the comparative example relay lens optical system 50' consists of the first lens group 51 and the second lens group 56 of the relay lens optical system 50 of the embodiment. Figure 6a illustrates the optical path in the relay lens optical system 50 according to the embodiment when the effective focal lengths of the first lens group 51 and the second lens group 56 are the same, and Figure 6b illustrates the optical path in the comparative example relay lens optical system 50' when the effective focal lengths of the first lens group 51 and the second lens group 56 are the same, and shows an example of the comparative example relay lens optical system 50' constituting a telecentric lens optical system.

In Figures 6a and 6b, for comparison, examples are shown where the effective focal lengths f of the first lens group 51 and the second lens group 56 are the same. In Figures 6a and 6b, A represents the center position of the first lens group 51, B represents the center position of the second lens group 56, and C represents the center position of the field lens 55. Additionally, in Figures 6a and 6b, reference numerals S1 and S1' represent the entrance pupils, and S2 and S2' represent the exit pupils. The entrance pupils S1 and S1' correspond to the processing modulation pattern forming surface of the spatial light modulator 30, and the exit pupils S2 and S2' can correspond to the entrance pupils of the focusing optical system 60.

As shown in Figure 6a, the relay lens optical system 50 of the embodiment may include a first lens group 51, a second lens group 56, and a field lens 55 located at an intermediate position from the center of the first lens group 51 and the second lens group 56. Therefore, according to the relay lens optical system 50 of the embodiment, the entrance pupil S1 is located at a distance of f/2 from the first lens group 51, and the exit pupil S2 may be located at a distance of f/2 from the second lens group 56.

In contrast, as shown in Figure 6b, the comparative relay lens optical system 50' may consist of a first lens group 51 and a second lens group 56. Therefore, according to the comparative relay lens optical system 50', the entrance pupil S1' is located at a distance f from the first lens group 51, and the exit pupil S2' is located at a distance f from the second lens group 56.

As can be seen from the comparison of Figures 6a and 6b, compared with the intermediate lens optical system 50' of the comparative example, the intermediate lens optical system 50 of the embodiment further includes a field lens 55 between the first lens group 51 and the second lens group 56, thereby reducing the optical path length from 4f to 3f. Furthermore, a comparison between the relay lens optical system 50 of the embodiment described later in Figure 9a and the relay lens optical system 50' of the comparative example in Figure 11a shows that the relay lens optical system 50' of the comparative example requires more lenses when using a telecentric lens optical system compared to when it does not use a telecentric lens optical system. In the relay lens optical system 50 of the embodiment, since the field lens 55 replaces this function, the number of lenses and the optical path length can be reduced more effectively.

As described above, the relay lens optical system 50 of the embodiment includes a field lens 55 between the first lens group 51 and the second lens group 56, thereby reducing the length of the light path and thus reducing the overall size of the optical system and the corresponding laser processing apparatus 100.

On the other hand, Figure 5 shows an example where the first lens group 51 and the second lens group 56 are each composed of two lenses; this is merely illustrative, and the embodiments are not limited thereto. Additionally, Figure 5 shows an example where the field lens 55 is composed of a single lens, and the embodiments are not limited thereto. For example, the first lens group 51, the second lens group 56, and the field lens 55 disposed therebetween can be designed in various ways to form a 3f lens unit system in the relay lens optical system 50.

This relay lens optical system 50 can transmit the image of the processing modulation pattern formed by the spatial light modulator 30 to the entrance pupil of the focusing optical system 60. The focusing optical system 60 can focus the laser light transmitted through the relay lens optical system 50 inside the processing object 1 placed on the support stage 5 to form a focusing point.

At this time, as described above, based on the processing modulation pattern formed in the spatial light modulator 30, multiple laser light focusing points can be obtained at different depths within the processing object 1. This allows modification regions to be formed at each of the multiple focusing points, thus creating modification regions that are spaced apart in the depth direction, or creating modification regions that expand in the depth direction by connecting the modification regions formed at the multiple focusing points.

For example, as shown in Figure 3, a first focusing point P1 and a second focusing point P2 are formed at a first depth d1 and a second depth d2 inside the object being processed, thereby simultaneously forming a first modified region 4a and a second modified region 4b at the first depth d1 and the second depth d2.

Therefore, under the control of the stage position control unit 70, the stage 3 is moved along the cutting predetermined line L, thereby moving the object to be processed. At the same time, when the laser light is focused inside the object to be processed, a discontinuous arrangement of first modified regions 4a is formed at the first focusing point P1 position at the first depth d1 along the cutting predetermined line L, and a discontinuous arrangement of second modified regions 4b is formed at the second focusing point P2 position at the second depth d2, which is different from the first depth d1.

That is, by moving the object being processed 1, an arrangement of first modified regions 4a can be formed at a first depth d1 and an arrangement of second modified regions 4b can be formed at a second depth d2. At this time, during a duty cycle, the first modified regions 4a and the second modified regions 4b, which are formed simultaneously and adjacent to each other in the depth direction, can exist in a state of being separated from each other, or they can merge in the depth direction to form an enlarged modified region 4'.

Therefore, according to the laser processing apparatus 100 of the embodiment, during one processing process along the predetermined cutting line L, multiple cutting lines can be formed in the depth direction inside the processed object 1, or a single cutting line including the enlarged modified region 4' can be formed, thereby reducing the number of times the cutting process is repeated along the predetermined cutting line L, and thus shortening the cutting process time.

On the other hand, referring again to FIG1, the condensing optical system 60 may include an objective lens 61, which focuses the laser light transmitted by the relay lens optical system 50 within the object being processed 1. Furthermore, according to the embodiment, the laser processing apparatus 100 may further include a reflector 101 between the relay lens optical system 50 and the objective lens 61 of the condensing optical system 60. When the condensing optical system 60 includes only the objective lens 61, the entrance pupil of the condensing optical system 60 transmitting the image of the processed modulation pattern may correspond to the entrance pupil of the objective lens 61.

On the other hand, Figures 7 and 8 show other embodiments of the optical system configuration that can be applied to the laser processing apparatus 100 of Figure 1. In Figures 1, 7, and 8, the spacing between optical components, the size and shape of the optical components, etc., are shown only illustratively to illustrate the arrangement relationship, and the embodiments are not limited thereto.

Referring to Figures 7 and 8, the focusing optical system 60 may further include a beam expander 65 between the relay lens optical system 50 and the objective lens 61 to broaden the beamwidth of the laser light. As illustrated in Figure 7, the beam expander 65 may be positioned between the relay lens optical system 50 and the mirror 101. Alternatively, as illustrated in Figure 8, the beam expander 65 may also be positioned between the mirror 101 and the objective lens 61.

As illustrated in Figures 7 and 8, when the focusing optical system 60 further includes a beam expander 65, the entrance pupil of the focusing optical system 60 that transmits the image of the processed modulation pattern can correspond to the entrance pupil of the beam expander 65.

On the other hand, Figure 8 shows an embodiment of the optical system configuration applicable to the laser processing apparatus 100 of Figure 1. When compared with Figures 1 and 7, not only is the arrangement of the beam expander 65 different, but the arrangement of the spatial light modulator 30 is also different.

Referring to Figure 8, when the direction of travel of the laser light emitted from the laser source 10, or the direction perpendicular to said direction, is referred to as the first travel direction, the laser processing apparatus 100 may be configured to arrange the spatial light modulator 30 parallel to the first travel direction. For this purpose, the laser processing apparatus 100 may further include an optical component 40, which is configured to obliquely incident the laser light onto the spatial light modulator 30 and to cause the laser light modulated and reflected from the spatial light modulator 30 to travel in a direction parallel to the first travel direction. The travel direction of the laser light incident on the optical component 40 from the side of the laser source 10 may correspond to the first travel direction.

Figure 8 shows an example of an optical component 40 having a triangular cross-sectional structure. The optical component 40 may include a first surface 41 and a second surface 43 that are angled to each other and tilted relative to the spatial light modulator 30, and a third surface 45 located on the opposite side of the spatial light modulator 30.

The optical component 40 may be a prism structure, in which case the first surface 41 and the second surface 43 are refractive/transmitting surfaces, and the third surface 45 may be an internal reflective surface. The third surface 45 may be arranged parallel to the spatial light modulator 30, for example. As described above, when the optical component 40 is a prism structure, laser light incident on the optical component 40 along the first travel direction can be refracted/transmitted through the first surface 41, and internally reflected at the third surface 45 to be refracted/transmitted through the first surface 41 again and incident on the spatial light modulator 30. In the spatial light modulator 30, the laser light modulated and reflected in a manner that forms a processing modulation pattern can be refracted/passed through the second surface 43, and internally reflected at the third surface 45 and refracted/passed through the second surface 43 again, traveling along the first travel direction and transmitted to the relay lens optical system 50.

As another example, the first surface 41 and the second surface 43 of the optical component 40 can be a first reflective surface and a second reflective surface, respectively. In this case, the first surface 41 is configured to reflect laser light incident in the first travel direction and obliquely incident it into the spatial light modulator 30, and the second surface 43 can be configured to reflect the laser light modulated and reflected in the spatial light modulator 30 in a manner that forms a processing modulation pattern and cause it to travel along the first travel direction. The angle formed by the first surface 41 and the second surface 43 can be determined to obtain this travel path.

On the other hand, in the laser processing apparatus 100 according to the embodiment, in order to ensure the required optical path without increasing the size of the optical system through proper arrangement, as shown in Figures 1, 7 and 8, mirrors 110, 111, 113 and 115 can be further applied. On the other hand, in Figures 1, 7 and 8, the first lens group 51 and the second lens group 56 of the intermediate lens optical system 50, the beam expander 65 of the focusing optical system 60 and the objective lens 61 are shown as a single lens; this is merely illustrative and not intended to limit the embodiment. As illustrated in Figure 9b below, the objective lens 61 can be composed of multiple lenses, and the beam expander 65 can also be composed of multiple lenses.

Referring again to Figure 1, the stage position control unit 70 can control the movement of the stage 3, which is connected to the support stage 5 on which the object to be processed 1 is placed. The stage 3 can be configured to move in a two-dimensional plane (xy plane). The stage position control unit 70 can control the movement of the stage 3 in the two-dimensional plane.

On the other hand, as described above, when an optical system position control unit is included, the optical system position control unit can change, for example, the position of the focusing optical system 60 or the objective lens 61 in the optical axis direction (z direction). As another example, the optical system position control unit can change the position of the entire optical system of the laser processing apparatus 100 or the focusing optical system 60 including the objective lens 61 and the beam expander 65 in the optical axis direction (z direction). This allows a cutting line to be formed at a depth set at the upper surface 1a of the object being processed 1, and also allows the cutting line formation depth to be changed.

Figures 9a and 9b schematically show the optical paths in the entire lens optical system, including the relay lens optical system 50 and the laser processing apparatus 100 comprising the relay lens optical system 50, according to an embodiment. Table 1 shows the design data of the relay lens optical system 50 of the embodiment according to Figure 9a, as well as the lens material and refractive power. Figures 10a, 10b, and 10c respectively show the modulation transfer function (MTF) performance, aberrations (chromatic aberration, astigmatism, distortion), and optical aberrations of the relay lens optical system 50 and the entire lens optical system, including the laser processing apparatus 100 comprising the relay lens optical system 50, formed using the design data in Table 1.

Referring to Figures 9a and 9b and Table 1, in the relay lens optical system 50 according to the embodiment, the first lens group (lens 1) 51 may include two lenses 52: G1 and 53: G2, the field lens 55 includes one lens G1, and the second lens group (lens 2) 56 includes two lenses 57: G1 and 58: G2. The first lens group 51 may include, for example, a lens 52: G1 with positive refractive power and a lens 53: G2 with negative refractive power. The field lens 55 may include, for example, a lens G1 with positive refractive power. The second lens group 56 may include, for example, a lens 57: G1 with positive refractive power and a lens 58: G2 with negative refractive power. In Table 1, G1 represents a lens with positive refractive power, and G2 represents a lens with negative refractive power.

On the other hand, as shown in FIG9b, the condensing optical system 60 may include a beam expander 65 and an objective lens 61, and the beam expander 65 includes multiple lenses, and the objective lens 61 may include multiple lenses. As shown in FIG9b, when the condensing optical system 60 includes a beam expander 65 and an objective lens 61, the entrance pupil of the condensing optical system 60 may correspond to the entrance pupil of the beam expander.

In Figure 9b, the starting point S1, representing the length of the optical system, represents the entrance pupil of the relay lens optical system 50, which corresponds to the processing modulation pattern forming surface of the spatial light modulator 30. Point S2 is the exit pupil of the relay lens optical system 50 and corresponds to the entrance pupil of the condenser optical system 60. Point I is the focal point of the objective lens 61 of the condenser optical system 60, which corresponds to the focusing point of the basic light component inside the processing object 1. The lens optical system of the laser processing apparatus 100 can be composed of the relay lens optical system 50 and the condenser optical system 60, and the length of the lens optical system of the laser processing apparatus 100 can correspond to the distance from the starting point S1 to point I (①).

When designing the relay lens optical system 50 using the data in Table 1, as shown in Figures 10a, 10b, and 10c, it can be seen that the relay lens optical system 50 of the embodiment and the entire lens optical system including the laser processing apparatus 100 of the relay lens optical system 50 exhibit good MTF performance, aberrations (chromatic aberration, astigmatism, distortion), and optical aberrations. In addition, when the relay lens optical system 50 is designed using the data in Table 1, the optical path length of the relay lens optical system 50 in the embodiment (the distance from the starting point S1 to point S2 (②)) is about 913.356 mm, and the optical path length of the entire lens system of the laser processing apparatus 100 (the distance from the starting point S1 to point I (①)) can be about 1150 mm.

Figures 11a and 11b schematically show a comparative relay lens optical system 50' designed to have similar optical performance to the relay lens optical system 50 of the embodiment, and the optical path in the entire lens optical system including the laser processing apparatus of the relay lens optical system 50'. Table 2 shows the design data of the comparative relay lens optical system 50' of Figure 11a, as well as the lens material and refractive power. Figures 12a, 12b, and 12c respectively show the MTF performance, aberrations (chromatic aberration, astigmatism, distortion), and optical aberrations of the comparative relay lens optical system 50' and the entire lens optical system including the laser processing apparatus of the relay lens optical system 50', formed using the design data in Table 2.

Referring to Figures 11a and 11b and Table 2, the comparative example relay lens optical system 50' consists of a first lens group (lens 1) 51' and a second lens group (lens 2) 56'. The first lens group (lens 1) 51' consists of three lenses 52':G1', 53':G2', and 54':G3', and the second lens group (lens 2) 56' can be composed of three lenses 57':G1', 58':G2', and 59':G3'. The first lens group 51' can be composed of a lens 52':G1' with positive refractive power, a lens 53':G2' with negative refractive power, and a lens 54':G3' with positive refractive power. The second lens group 56 may consist of a lens 57’:G1’ with positive refractive power, a lens 58’:G2’ with negative refractive power, and a lens 59’:G3’ with positive refractive power. On the other hand, the focusing optical system 60 may be the same as that in FIG9b.

In Figure 11b, the starting point S1', representing the length of the optical system, is the entrance pupil of the comparative relay lens optical system 50'. Point S2' represents the exit pupil of the comparative relay lens optical system 50' and the entrance pupil of the condenser optical system 60. Point I' corresponds to the focal position of the objective lens 61 of the condenser optical system 60. The entire lens system of the laser processing apparatus can be composed of the relay lens optical system 50' and the condenser optical system 60. The optical path length ①' of the entire lens system of the laser processing apparatus corresponds to the distance from the aforementioned starting point S1' to point I'.

When designing the comparative relay lens optical system 50' using the data in Table 2, as shown in Figures 12a, 12b, and 12c, it can be seen that the comparative relay lens optical system 50' and the entire lens system including the laser processing apparatus of the relay lens optical system 50' exhibit good MTF performance, aberrations (chromatic aberration, astigmatism, distortion), and optical aberrations. In addition, when designing the comparative relay lens optical system 50' using the data in Table 2, the optical path length of the comparative relay lens optical system 50' (distance ②' from the starting point S1' to point S2') is approximately 1145.356 mm, and the optical path length of the entire lens system of the laser processing apparatus (distance ①' from the starting point S1' to point I') is approximately 1382 mm.

As described above, the optical path length ② of the relay lens optical system 50 in the embodiment is approximately 913.356 mm, and the optical path length ① of the entire lens system including the relay lens optical system 50 is approximately 1150 mm. Conversely, the optical path length ②' of the relay lens optical system 50' in the comparative example is approximately 1145.356 mm, and the optical path length ①' of the entire lens system including the relay lens optical system 50' is approximately 1382 mm. Therefore, it can be confirmed that when the relay lens optical system 50 of the embodiment is applied, the optical path length can be reduced, and the overall size of the laser processing apparatus 100 can be reduced. Furthermore, according to the relay lens optical system 50 of the embodiment, by including a field lens 55 between the first lens group 51 and the second lens group 56, it can be confirmed that the number of lenses is reduced compared to the relay lens optical system 50' of the comparative example.

As described above, the relay lens optical system 50 according to the embodiment and the laser processing apparatus 100 using the relay lens optical system 50 can reduce the optical path length and the entire optical system, thereby reducing the size of the laser processing apparatus 100.

The relay lens optical system 50 and the laser processing apparatus 100 including the relay lens optical system 50 have been described with reference to the embodiments shown in the drawings. However, it should be understood that this is merely illustrative, and those skilled in the art can make various modifications and implement other equivalent embodiments accordingly. Therefore, the disclosed embodiments should be considered from the perspective of the description, and not from a self-limiting perspective. The scope of this specification should be interpreted as shown by the scope of the patent application and not the foregoing description, and includes all differences within its equivalent scope.

1: Processing Object 1a: Upper Surface 1b: Lower Surface 2: Functional Components 3: Stage 4': Expanded Modification Zone 4a: Modification Zone / First Modification Zone 4b: Modification Zone / Second Modification Zone 5: Support Stage 10: Laser Light Source 20: Control Unit 30: Spatial Light Modulator 30a: Entrance/Exit Surface 40: Optical Components 41: First Surface 43: Second Surface 45: Third Surface 50, 50': Relay Lens Optical System 51: First Lens Group 51': First Lens Group / Lens 1 52, 57: Lens/First Lens 52', 53', 54', 57', 58', 59', G1, G2, G3: Lens 53, 58: Lens/Second Lens 55: Field Lens 56: Second Lens Group 56': Second Lens Group/Lens 260: Condensing Optical System 61: Objective Lens 65: Beam Expander 70: Stage Position Control Unit 100: Laser Processing Device 101, 110, 111, 113, 115: Mirrors A, B, C: Center Position c1: Crack d1: First Depth d2: Second Depth f: Effective Focal Length/Distance _f1 , _f2 Focal length L: Cutting pre-defined line P1: First focal point P2: Second focal point S1: Object surface/processing modulation pattern forming surface/starting point/entrance pupil  S1': Starting point/entrance pupil S2: Upper surface/entrance pupil/exit pupil/point S2': Exit pupil/point x, y, z: Direction ①, ①', ②, ②': Distance/light path length

Figure 1 schematically shows a laser processing apparatus according to an embodiment. Figure 2 is a plan view schematically showing the configuration of the object being processed in Figure 1. Figure 3 shows an example of focusing laser light, modulated by a spatial light modulator according to a set processing modulation pattern, at multiple focal points inside the object being processed using a focusing optical system. Figure 4 is used to illustrate the principle of crack generation inside the object being processed in Figure 3. Figure 5 schematically shows an embodiment of the relay lens optical system of Figure 1. Figure 6a is used to illustrate the effect of reducing the optical path length of the relay lens optical system according to an embodiment. Figure 6b shows the optical path length of a comparative example of a relay lens optical system. Figures 7 and 8 show other embodiments of the optical system configuration applicable to the laser processing apparatus of Figure 1. Figures 9a and 9b schematically show the optical paths in the relay lens optical system according to the embodiments and the entire lens optical system of the laser processing apparatus 100 including the relay lens optical system. Figures 10a, 10b, and 10c respectively show the modulation conversion function (MTF) performance, aberrations (chromatic aberration, astigmatism, distortion), and optical aberrations of the relay lens optical system of the embodiments formed using the design data in Table 1 and the entire lens optical system of the laser processing apparatus including the relay lens optical system. Figures 11a and 11b schematically show the optical paths in the comparative relay lens optical system and the entire lens optical system including the laser processing apparatus of the relay lens optical system. Figures 12a, 12b, and 12c respectively show the MTF performance, aberrations (chromatic aberration, astigmatism, distortion), and optical aberrations of the comparative relay lens optical system and the entire lens optical system including the laser processing apparatus of the relay lens optical system formed using the design data in Table 2.

1: The target of the investigation

3: Taiwan

5: Support Platform

10: Laser Light Source

20: Control Department

30: Spatial Light Modulator

30a: Entrance/Exit Surface

50: Intermediate Lens Optical System

51: First Lens Group

55: Field Lens

56: Second Lens Group

60: Concentrated Optical System

61: Object Mirror

70: Position Control Unit

100: Laser processing equipment

101, 110: Reflecting Mirrors

x, y, z: Direction

Claims (18)

A laser processing apparatus includes: a laser light source for generating laser light; a spatial light modulator for modulating the laser light provided from the laser light source to form a processing modulation pattern; a focusing optical system for focusing the laser light modulated in the spatial light modulator onto a processing object; a relay lens optical system located between the spatial light modulator and the focusing optical system, configured to transmit an image of the processing modulation pattern formed by the spatial light modulator to the entrance pupil of the focusing optical system, and including a first lens group, a second lens group, and a field lens located between the first lens group and the second lens group; and a control unit for controlling the spatial light modulator to modulate the laser light according to the processing modulation pattern. The field lens is positioned midway between the first lens group and the second lens group. The relay lens optical system is configured to form a 3f lens unit. The laser processing apparatus as claimed in claim 1, wherein the first lens group and the second lens group each include two or more lenses. The laser processing apparatus as described in claim 2, wherein the first lens group and the second lens group each include a first lens with positive refractive power and a second lens with negative refractive power, the field lens is configured to have positive refractive power. The laser processing apparatus as claimed in claim 1, wherein the spatial light modulator forms the processing modulation pattern under the control of the control unit, so that the laser light modulated according to the processing modulation pattern is focused by the focusing optical system at multiple focusing points at different depths inside the object being processed. The laser processing apparatus as described in claim 4, wherein the laser light modulated according to the processing modulation pattern comprises: light components with different refractive intensities relative to the basic light components. The laser processing apparatus as claimed in claim 1, wherein the spatial light modulator includes a reflective spatial light modulator. The laser processing apparatus as described in claim 6 further includes an optical component, where the direction of travel of the laser light incident on the optical component from the laser light source side is referred to as the first direction of travel, the optical component is a prism structure, the prism structure being configured such that the laser light is incident obliquely on the spatial light modulator and that the laser light modulated and reflected in the spatial light modulator travels in a direction parallel to the first direction of travel, and that an internal reflecting surface is parallel to the spatial light modulator. The laser processing apparatus as claimed in claim 1, wherein the focusing optical system comprises: an objective lens for focusing incident laser light onto the object being processed. The laser processing apparatus as claimed in claim 8, wherein the focusing optical system further comprises: a beam expander, disposed between the relay lens optical system and the objective lens, to expand the beamwidth of the laser light. The laser processing apparatus as described in claim 9 further includes a reflector located between the relay lens optical system and the objective lens, and the beam expander is disposed between the relay lens optical system and the reflector or between the reflector and the objective lens. The laser processing apparatus as described in any one of claims 1 to 10 further comprises: a stage configured to perform two-dimensional planar movement; and a stage position control unit for controlling the two-dimensional planar movement of the stage. A laser processing apparatus includes: a laser light source for generating laser light; a reflective spatial light modulator for modulating the laser light provided from the laser light source to form a processing modulation pattern; a focusing optical system for focusing the laser light modulated in the reflective spatial light modulator onto a processing object, and including an objective lens; a relay lens optical system located between the reflective spatial light modulator and the focusing optical system, configured to transmit an image of the processing modulation pattern formed by the reflective spatial light modulator to the entrance pupil of the focusing optical system, and including a first lens group, a second lens group, and a field lens located between the first lens group and the second lens group; a stage configured to allow for two-dimensional planar movement; A stage position control unit controls the two-dimensional planar movement of the stage; and a control unit controls the spatial light modulator to modulate the laser light according to the processing modulation pattern, wherein the field lens is positioned midway between the first lens group and the second lens group, wherein the relay lens optical system is configured to form a 3f lens unit. The laser processing apparatus as described in claim 12, wherein the first lens group and the second lens group each include two or more lenses. The laser processing apparatus as claimed in claim 13, wherein the first lens group and the second lens group each include a first lens having positive refractive power and a second lens having negative refractive power, the field lens is configured to have positive refractive power. The laser processing apparatus as claimed in claim 12, wherein the spatial light modulator forms the processing modulation pattern under the control of the control unit, so that the laser light modulated according to the processing modulation pattern is focused by the focusing optical system at multiple focusing points at different depths inside the object being processed. The laser processing apparatus as described in claim 15, wherein the laser light modulated according to the processing modulation pattern comprises: light components with different refractive intensities relative to the basic light components. The laser processing apparatus as described in claim 12 further includes a reflector located between the relay lens optical system and the objective lens. The focusing optical system further includes a beam expander configured between the relay lens optical system and the reflector, or between the reflector and the objective lens, to expand the beamwidth of the laser light. The laser processing apparatus as described in any of claims 12 to 17 further includes an optical component, the optical component being a prism structure, and the prism structure, when the direction of travel of the laser light incident on the optical component from the laser light source side is referred to as the first direction of travel, is configured such that the laser light is obliquely incident on the spatial light modulator and that the laser light modulated and reflected in the spatial light modulator travels in a direction parallel to the first direction of travel, and that the internal reflecting surface is parallel to the spatial light modulator.