Laser grooving device and method for wafer

Abstract

The invention relates to a laser grooving device and method for a wafer. The device comprises a laser; the first beam expander is located on the path of the laser beam; the first light splitting crystal is located on the side, away from the laser, of the first beam expander and used for receiving the light beams collimated and expanded by the first beam expander to form a first light beam and a second light beam, the first light beam enters a first light path assembly to form a first processing light beam, and the second light beam enters a second light path assembly to form a second processing light beam; the second light beam enters a second light path assembly to form a second processing light beam; the second light splitting crystal is located on the path of the first processing light beam and the path of the second processing light beam and used for forming a first emergent light beam of the first processing light beam and a second emergent light beam of the second processing light beam, and the path of the first emergent light beam is the same as that of the second emergent light beam; a Wollaston prism; and a focus lens. By adopting the method, the processing efficiency can be improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a device and method for laser grooving of a wafer. Background Art

[0002] In the semiconductor manufacturing process, in order to meet the needs of high-frequency and high-speed devices, low-k materials are used to reduce parasitic capacitance in the circuit. However, low-k materials usually have poor heat resistance, bonding strength and stability, making it difficult to cut and separate chips.

[0003] In the related art, laser slotting technology is used to cut and separate chips. The laser beam ablates and removes the low-k layer in the cutting path, and then uses a cutter wheel or hidden cutting to cut the wafer. The laser slotting process includes using two smaller laser beams to form two thin lines on both sides of the cutting path, and then using a laser beam shaped into a flat-top distribution to process a wider groove in the middle of the cutting path to remove the low-k layer on the surface of the wafer.

[0004] In order to meet the different requirements of different products for slot width, laser slotting equipment needs to be able to adjust the line width and fine line spacing. At present, the laser beam can be shaped into a flat-top distribution by a diffractive optical element (DOE), and the line width can be adjusted by rotating the DOE, but the adjustment is difficult, and the high-order diffraction caused by the rotation may cause the edge effect to deteriorate. And it is difficult to improve the processing efficiency by using a small energy multiple scanning method for processing. Summary of the invention

[0005] Based on this, it is necessary to provide a wafer laser grooving device and method to address the above technical issues.

[0006] In a first aspect, the present application provides a laser grooving device for a wafer, the device comprising:

[0007] A laser, wherein the laser is used to emit a laser beam;

[0008] A first beam expander, located on the path of the laser beam and used for collimating and expanding the laser beam;

[0009] a first beam splitter crystal, the first beam splitter crystal is located at a side of the first beam expander away from the laser, and is used to receive the light beam after collimation and expansion by the first beam expander to form a first light beam and a second light beam, the first light beam enters the first optical path component to form a first processing light beam, and the second light beam enters the second optical path component to form a second processing light beam;

[0010] a second beam splitting crystal, the second beam splitting crystal being located on the paths of the first processing beam and the second processing beam, and being used to form a first outgoing beam of the first processing beam and a second outgoing beam of the second processing beam, the first outgoing beam and the second outgoing beam having the same path;

[0011] A Wollaston prism, wherein the Wollaston prism is located on the path of the first outgoing light beam and the second outgoing light beam, and is used for splitting the first outgoing light beam or the second outgoing light beam into two sub-beams;

[0012] A focusing mirror is used to focus the sub-beam.

[0013] In one embodiment, the device further comprises:

[0014] A light splitting module is placed between the Wollaston prism and the focusing lens, and is used to split the sub-beams formed by the Wollaston prism again to form more sub-beams.

[0015] In one embodiment, the first optical path component comprises:

[0016] A first optical gate, which is on the path of the first light beam and is used to control the propagation of the first light beam;

[0017] A shaping module, located at a side of the first optical gate away from the first beam splitting crystal, and configured to shape the first light beam into a rectangular light beam;

[0018] A first reflector, wherein the first reflector is located at a side of the shaping module away from the first optical gate and is used for reflecting the rectangular light beam to form the first processing light beam.

[0019] In one embodiment, the shaping module includes:

[0020] A slit aperture is used to shape the first light beam into a rectangular light beam.

[0021] In one embodiment, the shaping module further includes:

[0022] Cylindrical lens, used to focus a rectangular beam of light in a direction perpendicular to the slit diaphragm.

[0023] In one embodiment, the second optical path component comprises:

[0024] a second optical gate, the second optical gate being on the path of the second light beam and used for controlling the propagation of the second light beam;

[0025] a second reflector, the second reflector being located at a side of the second optical gate away from the first beam splitting crystal and being used for reflecting the second light beam;

[0026] A second beam expander is used to expand the outgoing light beam of the reflector to obtain the second processed light beam.

[0027] In a second aspect, the present application further provides a wafer laser grooving method, which is applied to any of the wafer laser grooving devices described above, and the method comprises:

[0028] The first optical gate is closed and the second optical gate is opened. The second light beam passes through the second optical path component and the second splitter crystal to form a second output light beam. The second output light beam passes through the Wollaston prism and the focusing lens, and is processed in parallel on both sides of the wafer cutting path to form two thin lines composed of multiple light spots.

[0029] In one embodiment, the method further comprises:

[0030] The second optical gate is closed and the first optical gate is opened. The first light beam is shaped into a rectangular light spot by the first optical path component, and then passes through the second beam splitting crystal, Wollaston prism and focusing lens to form two long strip light spots, forming a single wide line slot between the two thin lines.

[0031] In one embodiment, the method further comprises:

[0032] The width of the slit aperture in the shaping module is adjusted so as to adjust the width of the groove formed in the cutting path.

[0033] In one embodiment, the method further comprises:

[0034] The Wollaston prism is rotated so as to change the separation distance between the two thin lines formed on both sides of the cutting road.

[0035] In a third aspect, the present disclosure further provides a computer device, wherein the computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the laser grooving method of a wafer are implemented.

[0036] In a fourth aspect, the present disclosure further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the laser grooving method of a wafer are implemented.

[0037] In a fifth aspect, the present disclosure further provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the laser grooving method of a wafer are implemented.

[0038] The above-mentioned wafer laser grooving method has at least the following beneficial effects:

[0039] The embodiment scheme provided by the present disclosure divides the laser beam emitted by the laser into a first beam and a second beam, and processes the first optical path component and the second optical path component respectively to obtain a first processed beam and a second processed beam. The first processed beam is split by a Wollaston prism and then focused by a focusing lens, so that two thin lines are formed on both sides of the cutting path of the wafer. A single thin line can be composed of multiple light spots, and a uniform processing effect is achieved through superposition. The second processed beam enters the Wollaston prism and is then focused by a focusing lens to form a plurality of equal-sized, uniformly energetic long strip-shaped light spots on the wafer, so that multiple long strip-shaped light spots are processed simultaneously in the same cutting path, thereby improving processing efficiency.

[0040] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 A schematic diagram of a laser grooving device for a wafer in one embodiment;

[0043] Figure 2 A schematic diagram of an overall device for laser grooving a wafer in one embodiment;

[0044] Figure 3 is a schematic diagram of a first optical path component in one embodiment;

[0045] Figure 4 is a schematic diagram of a second optical path component in one embodiment;

[0046] Figure 5 is a schematic diagram of a single thin line consisting of three light spots in one embodiment;

[0047] Figure 6 A schematic diagram of forming a plurality of long light spots in one embodiment;

[0048] Figure 7 FIG. 1 is a schematic diagram of changing the separation distance of two light beams by rotating a Wollaston prism in one embodiment. DETAILED DESCRIPTION

[0049] In order to enable ordinary persons in the art to better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described here can be implemented in an order other than those illustrated or described here. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are only examples of devices and methods consistent with some aspects of the present disclosure as detailed in the attached claims. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, product or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements inherent to such process, method, product or device. In the absence of more restrictions, it is not excluded that there are other identical or equivalent elements in the process, method, product or device including the elements. For example, if the words first, second, etc. are used to represent the name, they do not represent any specific order.

[0051] Figure 1 Schematic diagram of a laser grooving device for a wafer in one embodiment.

[0052] In one embodiment of the present disclosure, a laser grooving device for a wafer includes: a laser 100 for emitting a laser beam to process a product.

[0053] The first beam expander 102 is located on the path of the laser beam and is used to collimate and expand the laser beam. The first beam expander can change the diameter and divergence angle of the laser beam, expand the cross-sectional size of the laser beam, and reduce the divergence angle of the beam, thereby improving the quality of the laser beam and improving the focusing performance.

[0054] The first beam splitter crystal 104 is located on the side of the first beam expander 102 away from the laser 100, and is used to receive the light beam after collimation and expansion by the first beam expander 102 to form a first light beam and a second light beam. The first light beam enters the first optical path component 106 to form a first processing light beam, and the second light beam enters the second optical path component 108 to form a second processing light beam. The energy of the first light beam and the second light beam can be adjusted according to actual needs, and the first beam splitter crystal 104 can be a polarization beam splitter prism.

[0055] The second spectroscopic crystal 110 is located on the path of the first processing light beam and the second processing light beam, and is used to form a first outgoing light beam of the first processing light beam and a second outgoing light beam of the second processing light beam, and the paths of the first outgoing light beam and the second outgoing light beam are the same. The second spectroscopic crystal 110 can be a beam combiner or a beam combining prism, which can combine two or more laser beams of different wavelengths, polarization states or propagation directions into one beam. In the embodiment of the present disclosure, the first processing light beam and the second processing light beam can be recombined into one beam, saving space for optical path arrangement and reducing the number of components.

[0056] The Wollaston prism 112 is located on the path of the first outgoing light beam and the second outgoing light beam, and is used to split the first outgoing light beam or the second outgoing light beam into two sub-beams. The Wollaston prism 112 can be used to split the incident linearly polarized light beam into two linearly polarized light beams whose polarization directions are perpendicular to each other, and the two light beams will be separated at a certain angle after leaving the prism, and the angle can depend on the birefringence property of the prism material. In the embodiment of the present disclosure, the Wollaston prism 112 can split the first outgoing light beam or the second outgoing light beam into two sub-beams with equal power and symmetrical distribution.

[0057] The focusing mirror 114 is used to focus the sub-beams.

[0058] The laser slotting device for the above-mentioned wafer divides the laser beam emitted by the laser into a first beam and a second beam, and processes them through the first optical path component and the second optical path component respectively to obtain a first processed beam and a second processed beam. The first processed beam is split by a Wollaston prism and then focused by a focusing lens, so that two thin lines are formed on both sides of the cutting path of the wafer. A single thin line can be composed of multiple light spots, and a uniform processing effect is achieved through superposition. The second processed beam enters the Wollaston prism and is then focused by a focusing lens to form multiple long strips of light spots of equal size and uniform energy on the wafer, so that multiple long strips of light spots can be processed simultaneously in the same cutting path, thereby improving processing efficiency.

[0059] In one embodiment of the present disclosure, Figure 2The schematic diagram of the overall device for laser grooving of a wafer in an embodiment also includes a spectroscopic module 200, which is placed between the Wollaston prism 112 and the focusing lens 114. The spectroscopic module 200 can split a single laser beam into multiple sub-beams to achieve more precise and efficient processing, and can include a multi-spot diffractive optical element (DOE, Diffractive Optical Element) or a spatial light modulator and other elements to shape the laser beam into multiple light spots. The multi-spot diffractive optical element etches a specific microstructure pattern on its surface so that the incident laser beam diffracts when passing through these microstructures, thereby generating multiple light spots of predetermined positions and intensities, and controlling the position, size and energy distribution of each light spot, including but not limited to 2-9 light spots. A spatial light modulator is a programmable optical device that can dynamically change the spatial distribution of incident light. A spatial light modulator is usually composed of a two-dimensional pixel array, and each pixel can independently adjust its phase or amplitude to control the shape and intensity distribution of the outgoing light. In the embodiments of the present disclosure, when the sub-beams are split again to form more sub-beams, the energy of each sub-beam is less than that of the original single laser beam. The sub-beams with smaller energy will form multiple focal points on the surface of the material. By controlling the position and energy distribution of these focal points, multiple repeated scans can be performed in the same area, so that the material is heated more evenly, the slotting effect is optimized, and it helps to reduce the deformation and cracks on the wafer surface and improve the flatness of the slot bottom and sidewalls. By using multiple sub-beams for processing at the same time, a larger area can be covered in one scan, which increases the processing speed.

[0060] In one embodiment of the present disclosure, Figure 3 Schematic diagram of a first optical path component in one embodiment, the first optical path component 106 includes:

[0061] The first optical shutter 300 is on the path of the first light beam and is used to control the propagation of the first light beam;

[0062] The shaping module 302 is located on the side of the first optical gate 300 away from the first beam splitting crystal 104, and is used to shape the first light beam into a rectangular light beam. The shaping module 302 can convert the original circular or elliptical light beam into a light beam of a specific shape to meet different processing requirements. In the embodiment of the present disclosure, the first light beam can be shaped into a rectangular light beam. The shaping module 302 may include a slit aperture, a microlens array, etc.

[0063] The first reflector 304 is located on the side of the shaping module 302 away from the first optical shutter 300 and is used to reflect the rectangular beam to form the first processing beam. The first reflector 304 is used to adjust the transmission direction of the rectangular beam, and multiple reflectors can be arranged according to actual conditions.

[0064] In one embodiment of the present disclosure, the shaping module 302 includes a slit aperture, and the slit aperture is used to shape the first light beam into a rectangular light beam.

[0065] The slit aperture usually consists of two parallel edges, forming a narrow opening, which is used to intercept and shape the laser beam, changing it from a circular spot to a rectangular spot. When laser beams of different shapes pass through the slit aperture, only part of the beam that passes through the slit can continue to propagate, and the rest is blocked. The beam passing through the slit forms an approximately rectangular spot. The length of this spot is determined by the width of the slit. The width of the slit can be changed to meet the needs of different processing groove widths.

[0066] In one embodiment of the present disclosure, the shaping module 302 further includes:

[0067] Cylindrical lens, used to focus a rectangular beam of light in a direction perpendicular to the slit diaphragm.

[0068] Cylindrical lenses are used in laser processing to focus or expand the beam in one direction while keeping the beam size unchanged in another direction. When used in combination with a slit diaphragm, the cylindrical lens can focus a rectangular beam in a direction perpendicular to the slit diaphragm, and in a direction parallel to the slit diaphragm, the cylindrical lens can expand the rectangular beam to more evenly cover the entire slit width. The combination of a slit diaphragm and a cylindrical lens can shape a circular spot into a slender and uniform rectangular spot, which is suitable for slotting processing.

[0069] In one embodiment of the present disclosure, Figure 4 Schematic diagram of a second optical path component in one embodiment, the second optical path component 108 includes:

[0070] The second optical shutter 400 is on the path of the second light beam, and the second optical shutter can be opened or closed to allow or prevent the second light beam from passing through.

[0071] The second reflector 402 is located at a side of the second optical shutter 400 away from the first beam splitting crystal 104 and is used to reflect the second light beam;

[0072] The second beam expander 404 is used to expand the output light beam of the second reflector 402 to obtain a second processed light beam, thereby improving the quality of the second processed light beam.

[0073] The embodiment of the present disclosure provides a method for laser grooving of a wafer, which can be applied to any of the above-mentioned laser grooving devices for wafers, including closing the first light gate 300 and opening the second light gate 400. The second light beam can pass through the second optical path component 108 normally, and obtain a second output light beam through the second spectroscopic crystal 110, which is transmitted to the Wollaston prism 112 and divided into two equal sub-beams, which can be further divided into multiple light beams by the spectroscopic module 200 and focused by the focusing lens 114, and are processed in parallel on both sides of the product cutting path to form two thin lines. A single thin line can be composed of multiple light spots, and a uniform processing effect can be achieved through superposition. The number and distribution of light spots can be controlled by adjusting the spectroscopic module to meet different processing requirements. Figure 5 Schematic diagram of a single thin line consisting of three light spots in an embodiment.

[0074] In one embodiment of the present disclosure, the method further includes:

[0075] The second shutter 400 is closed and the first shutter 300 is opened, so that a groove is formed in the cutting street.

[0076] The second optical gate 400 is closed, and the first optical gate 300 is opened. The first light beam forms a rectangular light spot after passing through the shaping module 302. The shaped rectangular light spot is flat-topped in the X direction and Gaussian in the Y direction. Then, it is transmitted to the second beam splitting crystal 110 through the first reflector 304 to obtain the first output light beam. The first output light beam enters the Wollaston prism 112 and is divided into two equal sub-beams. The two equal sub-beams can be split again through the beam splitting module 200 to form more sub-beams. The sub-beams are focused by the focusing mirror 114 to form a plurality of long strip-shaped light spots of equal size and uniform energy on the wafer, so as to realize the simultaneous processing of multiple long strip-shaped light spots in the same cutting path, improve the processing efficiency, and finally form a wide groove in the cutting path, remove the low-k layer, and ensure that the thermal influence of the edge of the cutting path is small to avoid damage to the wafer circuit. Figure 6 FIG. 1 is a schematic diagram of forming a plurality of long light spots in an embodiment.

[0077] In one embodiment of the present disclosure, the method further includes:

[0078] The width of the slit aperture in the shaping module 302 is adjusted so as to adjust the width of the groove formed in the cutting path.

[0079] When grooves of different widths need to be processed, the spot length of the first emergent light beam can be changed by adjusting the width of the slit aperture in the shaping module 302 .

[0080] In one embodiment of the present disclosure, the method further includes:

[0081] The Wollaston prism is rotated so as to change the separation distance between the two thin lines formed on both sides of the cutting road.

[0082] During beam processing, a motor can be used to drive the Wollaston prism to rotate and change the spacing of the second output beam, thereby adjusting the line width. Compared with the rotation when using a DOE device for splitting, it will not introduce the problem of beam quality degradation caused by high-order diffraction, and the adjustment is more convenient. Figure 7 FIG. 1 is a schematic diagram of changing the separation distance of two light beams by rotating a Wollaston prism in one embodiment.

[0083] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0084] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-described embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the attached claims.

Claims

1. A laser grooving device for a wafer, characterized in that: The device comprises: A laser, wherein the laser is used to emit a laser beam; A first beam expander, located on the path of the laser beam and used for collimating and expanding the laser beam; a first beam splitter crystal, the first beam splitter crystal is located at a side of the first beam expander away from the laser, and is used to receive the light beam after collimation and expansion by the first beam expander to form a first light beam and a second light beam, the first light beam enters the first optical path component to form a first processing light beam, and the second light beam enters the second optical path component to form a second processing light beam; a second beam splitting crystal, the second beam splitting crystal being located on the paths of the first processing beam and the second processing beam, and being used to form a first outgoing beam of the first processing beam and a second outgoing beam of the second processing beam, the first outgoing beam and the second outgoing beam having the same path; A Wollaston prism, wherein the Wollaston prism is located on the path of the first outgoing light beam and the second outgoing light beam, and is used for splitting the first outgoing light beam or the second outgoing light beam into two sub-beams; A focusing mirror, the focusing mirror is used to focus the sub-beam; A light splitting module is placed between the Wollaston prism and the focusing lens, and is used to split the sub-beams formed by the Wollaston prism again to form more sub-beams.

2. The device according to claim 1, characterized in that The first optical path component comprises: A first optical gate, which is on the path of the first light beam and is used to control the propagation of the first light beam; A shaping module, located at a side of the first optical gate away from the first beam splitting crystal, and configured to shape the first light beam into a rectangular light beam; A first reflector, wherein the first reflector is located at a side of the shaping module away from the first optical gate and is used for reflecting the rectangular light beam to form the first processing light beam.

3. The device according to claim 2, characterized in that The shaping module comprises: A slit aperture is used to shape the first light beam into a rectangular light beam.

4. The device according to claim 3, characterized in that The shaping module also includes: Cylindrical lens, used to focus a rectangular beam of light in a direction perpendicular to the slit diaphragm.

5. The device according to claim 1, characterized in that The second optical path component comprises: a second optical gate, the second optical gate being on the path of the second light beam and used for controlling the propagation of the second light beam; a second reflector, the second reflector being located at a side of the second optical gate away from the first beam splitting crystal and being used for reflecting the second light beam; A second beam expander is used to expand the outgoing light beam of the reflector to obtain the second processed light beam.

6. A method for laser grooving a wafer, characterized in that: A laser grooving device applied to a wafer according to any one of claims 1 to 5, the method comprising: The first optical gate is closed and the second optical gate is opened. The second light beam passes through the second optical path component and the second splitter crystal to form a second output light beam. The second output light beam passes through the Wollaston prism and the focusing lens, and is processed in parallel on both sides of the wafer cutting path to form two thin lines composed of multiple light spots.

7. The method according to claim 6, characterized in that The method further comprises: The second optical gate is closed and the first optical gate is opened. The first light beam is shaped into a rectangular light spot by the first optical path component, and then passes through the second beam splitting crystal, Wollaston prism and focusing lens to form two long strip light spots, forming a single wide line slot between the two thin lines.

8. The method according to claim 6, characterized in that The method further comprises: The width of the slit aperture in the shaping module is adjusted so as to adjust the width of the groove formed in the cutting path.

9. The method according to claim 6, characterized in that The method further comprises: The Wollaston prism is rotated so as to change the separation distance between the two thin lines formed on both sides of the cutting road.

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