TW202305911A - Method for manufacturing chips capable of manufacturing chips free from chip defects when a wafer on which a resin layer is disposed is divided, laminated and thermo-compressed - Google Patents

Abstract

An object of the invention is to manufacture chips free from chip defects when a wafer on which a resin layer is disposed is divided, laminated and thermo-compressed. To achieve the object, a chip manufacturing method is provided for manufacturing chips by dividing a wafer having a resin layer on a first surface along a predetermined processing line, and includes the steps of: a protective film forming step, in which a protective film is formed on the first surface; a processing groove forming step, in which, after the protective film forming step, the wafer is irradiated with a first laser beam having an absorptive wavelength for the wafer from the first surface side along the predetermined processing line, so as to form processing grooves on the wafer; a cured region removing step, in which, after the processing groove forming step, a cured region of the cured resin layer is removed; and a protective film removing step, in which, after the cured region removing step, the protective film formed on the first surface is removed. Moreover, the method for manufacturing chips divides the wafer along the processing grooves to form individual chips.

Description

Wafer Manufacturing Method

The present invention relates to a method of manufacturing a wafer, which divides a wafer provided with a resin layer to manufacture wafers.

In the manufacturing process of component wafers used in electronic devices such as mobile phones and personal computers, firstly, a plurality of intersecting planned processing lines (dicing lines) are set on the front surface of the wafer made of materials such as semiconductors. Then, elements such as IC (Integrated Circuit, integrated circuit) and LSI (Large-scale Integrated circuit, large-scale integrated circuit) are formed in each area divided by the planned processing line. Thereafter, when the divided wafers are processed along the planned processing lines, individual element wafers are formed.

In dividing a wafer, for example, a laser processing device capable of performing laser processing on the wafer using a laser beam is used. The laser processing apparatus, for example, irradiates the wafer with a laser beam of a wavelength that the wafer can absorb along a line to be processed to perform ablation processing on the wafer.

In recent years, in order to reduce the mounting area of component chips, HBM (High Bandwidth Memory, high-bandwidth memory) has been developed in which multiple chips are vertically stacked and electrically connected to each other and integrated through TSV (Through Silicon Via). and other technologies. Furthermore, a resin layer called NCF (Non Conductive Film, non-conductive film) used for laminating a plurality of chips has been developed (see Patent Document 1 and Patent Document 2).

When a resin layer is arranged on the front surface of a wafer before being broken into wafers, and a laser beam is irradiated on the wafer to divide the wafer together with the resin layer, a wafer having a resin layer on one side can be obtained. Then, when the obtained wafers are stacked to form a laminate, and each resin layer is heated while expanding the laminate by pressing the laminate from above and below, and the respective wafers are thermocompression-bonded, it is possible to obtain a laminate formed by the resin layer. Chips attached to each other and integrated. [Prior art literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2009-277818 [Patent Document 2] Japanese Unexamined Patent Publication No. 2016-92188

[Problems to be Solved by the Invention] However, if the wafer on which the resin layer is placed is subjected to ablation processing with a laser beam, the resin layer will be partially deteriorated around the irradiated portion of the laser beam due to the heat generated by the irradiation of the laser beam. and harden. Then, when a plurality of chips are laminated and bonded by thermocompression, the hardened area of the resin layer is not easy to expand, and the air bubbles entering the hardened area of the resin layer are also difficult to eliminate.

Therefore, if a hardened region is formed in the resin layer, the thermocompression bonding may not be performed properly and the individual wafers may not be integrated with a predetermined quality, and the integrated wafers may be easily separated. The case of unnecessary electrical connection. That is, there are cases where part of the resin layer hardens and becomes a cause of wafer failure.

The present invention has been made in view of these problems, and an object thereof is to provide a wafer manufacturing method, which manufactures wafers by dividing a wafer on which a resin layer is placed, and when laminating and thermocompression-bonding the wafers Wafer failure does not occur.

[Technical means to solve the problem] According to one aspect of the present invention, there is provided a wafer manufacturing method, which divides a wafer having a resin layer on a first surface along a line to be processed to manufacture wafers, and is characterized in that it includes: a protective film forming step, wherein Forming a protective film on the first surface; processing a groove forming step, after the protective film forming step, irradiating the wafer with a first absorbing wavelength of the wafer from the first surface side along the line to be processed; a laser beam to form processing grooves in the wafer; a hardened area removal step, which removes the hardened area of the resin layer that has been cured after the processing groove forming step; and a protective film removal step, which removes the hardened area after the hardened After the area removing step, the protective film formed on the first surface is removed, and the wafer manufacturing method forms individual wafers by dividing the wafer along the processing groove.

Preferably, in the hardened area removing step, the hardened area is removed by irradiating a second laser beam to an area including the hardened area of the resin layer.

And, preferably, the energy density of the second laser beam is lower than the energy density of the first laser beam.

Moreover, preferably, the first laser beam is a Gaussian beam, and the second laser beam is a top-hat beam.

Still preferably, in the step of removing the hardened area, the wafer is irradiated with the second laser beam having a width wider than that of the processing groove.

And, preferably, in the step of removing the hardened area, the second laser beam is trimmed into an ellipse with different lengths of the long axis and short axis, a rectangle with different lengths of the long side and short side, or a four-sided shape. A square of equal length irradiates the wafer with the second laser beam in a state where the long axis, the long side or one of the sides faces a direction perpendicular to the planned processing line.

Also, preferably, in the hardened area removing step, the second laser beam is irradiated in one or both of a direction parallel to the line to be processed and a direction perpendicular to the wafer to be processed.

And, preferably, in the hardened area removing step, the second laser beam is irradiated to the area including the hardened area of the resin layer under a condition smaller than a threshold value at which the resin layer is hardened.

And, preferably, in the hardened area removing step, the hardened area of the resin layer is cut with a cutting blade.

Then, preferably, in the process groove forming step, the first laser beam is branched in one or both of a direction parallel to the line to be processed and a direction perpendicular to the line to be processed on the wafer and irradiated to the wafer.

And, preferably, the resin layer is NCF.

Furthermore, preferably, the protective film has a thickness of 5 μm or more.

And, preferably, the processing groove formed in the processing groove forming step does not reach the second surface of the wafer parallel to the first surface, and, by applying an external force to the wafer, the processing groove is formed along the processing groove. The grooves separate the wafer.

[Efficacy of the invention] In the wafer manufacturing method according to one aspect of the present invention, a protective film is formed on the first surface of a wafer having a resin layer on the first surface, and the wafer is divided by irradiating the first laser beam. At this time, although a hardened area is formed in the resin layer, this hardened area is removed later, and the protective film is removed from the first surface. In this case, the hardened area of the resin layer hardened by the first laser beam does not remain on the obtained wafer. Therefore, when the obtained plurality of wafers are laminated and thermocompression-bonded, wafer defects due to hardened regions do not occur.

Therefore, according to one aspect of the present invention, there is provided a method of manufacturing a wafer, which manufactures a wafer by dividing a wafer on which a resin layer is placed, and does not Wafer failure occurs.

Embodiments of one aspect of the present invention will be described with reference to the accompanying drawings. In the wafer manufacturing method of this embodiment, the wafer having the resin layer on the first surface is divided along the processing line to manufacture individual wafers. First, a wafer to be processed in the wafer manufacturing method of the present embodiment will be described. FIG. 1 is a schematic perspective view of a wafer 1 in which a resin layer 7 is disposed on a first surface (front surface) 1 a.

The wafer 1 is, for example, a disk-shaped wafer made of Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor materials. The first surface 1a of the wafer 1 is divided by a plurality of planned processing lines 3 intersecting each other. In addition, elements 5 such as ICs and LSIs are formed in the regions of the first surface 1 a of the wafer 1 divided by the lines 3 to be processed.

However, the material, shape, structure, size, etc. of the wafer 1 are not limited. For example, a substrate or the like made of other materials such as semiconductors, ceramics, resins, and metals can also be used as the wafer 1 . Furthermore, there is no limitation on the type, quantity, shape, structure, size, arrangement, etc. of the elements 5 , and the wafer 1 may not be formed with the elements 5 .

When the wafer 1 provided with the plurality of devices 5 on the first surface 1 a is divided along the line to be processed 3 , a plurality of wafers respectively provided with the devices 5 can be obtained. The wafer 1 is carried into the processing apparatus in the state of the frame unit 13 shown in FIG. 1 and divided. That is, the processed and divided wafer 1 may be previously integrated with an adhesive film 9 called a dicing adhesive film and a ring-shaped frame 11 , and the frame unit 13 may be formed.

If the wafer 1 is handled through the frame 11 and the adhesive film 9, the wafer 1 can be protected from the shock accompanying the transfer of the wafer 1, so the handling of the wafer 1 becomes easy. In addition, individual wafers formed by dividing the wafer 1 are supported by the adhesive film 9, so that the wafers formed can be easily handled. Thereafter, when the adhesive film 9 is expanded radially outward inside the opening of the frame 11, the intervals between the wafers are widened, making it easier to pick up the wafers.

The adhesive film 9 includes: a flexible sheet-shaped base material and an adhesive layer disposed on the base material. As the base material, for example, PO (polyolefin), PET (polyethylene terephthalate), polyvinyl chloride, polystyrene, or the like can be used. In addition, for the adhesive layer, for example, silicone rubber, acrylic material, epoxy material, etc. can be used.

The ring-shaped frame 11 is formed of materials such as metal, and has an opening whose diameter is larger than that of the wafer 1 . On the periphery of the opening of the frame 11 , an adhesive film 9 is pasted in advance to close the opening, and the adhesive surface of the adhesive film 9 is exposed at the opening. Then, if the wafer 1 is pasted on the adhesive surface exposed in the opening of the adhesive film 9 pasted on the frame 11, the frame unit 13 can be formed.

The wafers obtained by dividing the wafer 1 are mounted on a predetermined mounting object and used. In recent years, in order to reduce the mounting area of the chip, increase the functionality of the chip and save power, etc., a plurality of chips are vertically stacked and electrically connected to each other and integrated. For example, if a resin film is interposed between the chips, and the chips are connected to each other through TSVs, and the laminated body of the chips is bonded by thermocompression, the chips are attached and bonded by the softened resin film. integration.

Here, it is inefficient to carry out the operation of disposing the resin film on each wafer obtained by dividing the wafer 1 . Then, a resin layer 7 called NCF is preliminarily arranged on the first surface 1 a side of the wafer 1 to be divided, and the wafer 1 is divided together with the resin layer 7 . In this case, individual wafers having the resin layer 7 on one surface can be efficiently formed.

In order to dispose the resin layer 7 on the first surface 1 a side of the wafer 1 , for example, a sheet-shaped resin film may be attached to the first surface 1 a. Alternatively, the resin layer 7 may be provided by applying a liquid resin to the first surface 1 a and curing it. The resin layer 7 is made of, for example, polyolefin, polyester, epoxy resin, acrylic resin, silicon resin, polyimide resin and other materials, and may also be formed by a combination thereof. The resin layer 7 may also be mixed with various functional additives, and the composition of the resin layer 7 is not particularly limited.

When the wafers obtained by dividing the wafer 1 are stacked to form a laminate, and the laminate is pressed with a predetermined force while being heated at a predetermined temperature, the resin layer 7 is moderately softened and be expanded. Then, when the heating of the laminated body is stopped, the resin layer 7 is hardened and the wafers are attached to each other.

For example, the wafer 1 is a thin silicon wafer with a thickness of about 50 μm, and the thickness of the resin layer 7 is about 20 μm. For example, the width of the line 3 to be processed is set to about 80 μm, and a 5 mm square wafer is manufactured from the wafer 1 . As a method of dividing the wafer 1, dicing with an annular dicing blade is also conceivable, but if the thin wafer 1 is diced, notches called cracks are likely to be formed on the second surface 1b side.

In addition, the following method is also conceivable: condensing a laser beam of a wavelength penetrating the wafer 1 on the wafer 1 to form a modified layer, and using the modified layer as a starting point to form a crack extending upward and downward, and the wafer 1 for splitting. However, when the wafer 1 is thin, it becomes impossible to ignore the variation in the formation height of the modified layer due to the variation in the thickness of the glue film 9 . That is, it becomes difficult to divide the wafer 1 uniformly along the line to be processed 3 .

Therefore, in the division of the wafer 1, a laser processing device can be used, which can irradiate the wafer 1 with an absorbing wavelength (absorptive to the wafer 1) along the planned processing line 3. wavelength) of the laser beam, and the wafer 1 is ablated. If the wafer 1 is ablated along the planned processing line 3 , processing grooves along the processing planning line 3 are formed on the wafer 1 , and the wafer 1 is divided along the processing grooves to obtain individual wafers. At this time, the resin layer 7 disposed on the first surface 1a of the wafer 1 will also be broken.

However, the resin layer 7 is heated by the heat generated by irradiation of the laser beam in the periphery where the processing groove is formed, and the resin layer 7 is partially denatured and hardened. Therefore, hardened regions remain in the resin layer 7 along the edges of each formed wafer. When a plurality of chips are bonded by thermocompression, the hardened area of the resin layer 7 is not easy to expand properly, and the air bubbles entering the hardened area of the resin layer 7 are also difficult to eliminate.

Therefore, there may be cases where the individual chips are not properly integrated by thermocompression bonding, individual integrated chips may be easily separated, and unnecessary electrical connections may be formed through air bubbles. That is, partial hardening of the resin layer 7 may cause wafer failure.

Then, according to the wafer manufacturing method of this embodiment, a wafer that does not cause wafer defects during lamination and thermocompression bonding can be manufactured. Hereinafter, each step of the wafer manufacturing method of this embodiment will be described. FIG. 10 is a flowchart showing the flow of each step in the wafer manufacturing method of this embodiment.

In the wafer manufacturing method of this embodiment, first, the protective film forming step S10 is performed. FIG. 2 is a schematic cross-sectional view showing step S10 of forming a protective film. In the protective film forming step S10 , a protective film is formed on the first surface 1 a of the wafer 1 .

The protective film forming step S10 is implemented by the spin coater 2, for example. The spin coater 2 includes: a chuck table 6 that rotatably supports the wafer 1 (frame unit 13 ); and a liquid resin supply nozzle 14 that supplies the wafer 1 supported by the chuck table 6 to be a protective film. The liquid resin 16 of the material.

The chuck table 6 includes: a frame body 10 formed with a concave portion opened upward; and a porous member 12 housed in the concave portion of the frame body 10 . A suction path (not shown) is formed in the housing 10 , and one end of the suction path is connected to a suction source (not shown), and the other end is connected to the porous member 12 . When the wafer 1 is placed on the chuck table 6 through the adhesive film 9 , and the suction source is operated to apply negative pressure to the wafer 1 , the wafer 1 can be sucked and held by the chuck table 6 .

A plurality of jigs 8 capable of holding the frame 11 of the frame unit 13 placed on the chuck table 6 are disposed around the chuck table 6 . Furthermore, a pedestal 4 supporting the chuck table 6 is connected to the center of the bottom surface of the frame body 10 of the chuck table 6 . A not-shown rotational drive source such as a motor is connected to the base 4 , and when the rotational drive source is operated, the chuck table 6 can be rotated around a rotational axis perpendicular to the upper surface.

The liquid resin supply nozzle 14 has a discharge port positioned above the center of the upper surface of the chuck table 6 , and supplies the liquid resin 16 to the first surface 1 a of the wafer 1 held by the chuck table 6 . The liquid resin 16 supplied from the liquid resin supply nozzle 14 to the wafer 1 can be a water-soluble resin that solidifies when dried in the air. For example, as the liquid resin 16, polyvinyl alcohol, polyvinylpyrrolidone, "HOGOMAX (registered trademark)" series manufactured by DISCO Co., Ltd., etc. can be used. However, the liquid resin 16 is not limited thereto.

In the protective film forming step S10 , the frame unit 13 is carried into the spin coater 2 and placed on the chuck table 6 , the frame 11 is held by the chuck 8 and the wafer 1 is sucked and held by the chuck table 6 . Then, the liquid resin supply nozzle 14 is positioned above the center of the wafer 1, and the chuck table 6 is rotated at a high speed around the rotation axis while the rotary drive source is operated, and the liquid resin supply nozzle 14 supplies the liquid resin. The resin 16 is dripped onto the first surface 1 a of the wafer 1 .

In this way, the wafer 1 is spin-coated, and the first surface 1 a is covered with the liquid resin 16 . Thereafter, if the wafer 1 is placed in the atmosphere for more than 10 minutes and less than 30 minutes to solidify the liquid resin 16, a protective film 15 is provided on the first surface 1a of the wafer 1 (refer to FIG. ). FIG. 4(A) is an enlarged and schematic cross-sectional view of the wafer 1 on which the protective film 15 is formed.

One of the functions of the protective film 15 is to prevent, as will be described later, molten matter called debris scattered when the wafer 1 is ablated, from reattaching to the first surface 1 a of the wafer 1 . When the wafer 1 is ablated, debris will adhere to the upper surface of the protective film 15 . Then, when the protection film 15 is removed from the wafer 1 , the debris is also removed from the wafer 1 . Therefore, the first face 1a side of the wafer 1 is not contaminated with debris.

Here, in order to prevent chips and the like from reattaching to the wafer 1 , it is sufficient that the thickness of the protective film 15 is about 1 μm. However, in the protective film forming step S10 , it is desirable to arrange a relatively thick protective film 15 on the wafer 1 . For example, the thickness of the protective film 15 is preferably not less than 5 μm, more preferably not less than 7 μm and not more than 30 μm. If a thick protective film 15 is provided on the wafer 1 having the resin layer 7, as described later, when the wafer 1 is ablated, the expansion of the hardened region of the resin layer 7 can be reduced.

This is considered to be caused by the reduction of heat transfer from the chips to the resin layer 7 through the protective film 15 when high-temperature chips generated during the ablation process adhere to the surface of the protective film 15 . Alternatively, it is also considered that high-temperature chips are easily guided and discharged upward by the thick protective film 15 . Alternatively, it is also considered to be due to the promotion of heat dissipation by the thick protective film 15 and the reduction of the influence of heat on the resin layer 7 . In any case, the thick protective film 15 functions to reduce the expansion of the cured region of the resin layer 7 .

In order to form a thick protective film 15 on the wafer 1 including the resin layer 7 , it is conceivable to repeatedly perform spin coating. That is, the first spin coating is performed, and the liquid resin 16 is applied and dried on the first surface 1a side of the wafer 1 to form the first layer of the protective film 15, and then the second spin coating is performed, and the first layer is formed on the first layer. The liquid resin 16 is applied and dried to form the second layer of the protective film 15 . By repeating the spin coating in this way, a thick protective film 15 can be formed on the first surface 1 a of the wafer 1 .

When performing spin coating multiple times to form thick protective film 15 , in order to form protective film 15 with good upper surface flatness in a short time, film formation conditions may be changed at each stage of spin coating. For example, in the initial spin coating, the rotation speed of the chuck table 6 is reduced to form a thick layer, and in the final spin coating, the rotation speed of the chuck table 6 is increased to form a layer with a good flatness of the upper surface.

After the protective film forming step S10, the processing groove forming step S20 is implemented, which irradiates the wafer 1 with an absorbing wavelength (absorptive to the wafer 1) to the wafer 1 from the first surface 1a side along the processing line 3 wavelength) of the first laser beam to form a processing groove. FIG. 3 is a cross-sectional view schematically showing the processing groove forming step S20.

The processing groove forming step S20 is implemented, for example, by the laser processing device 18 shown in FIG. 3 . The laser processing device 18 includes: a chuck table 6a that sucks and holds the wafer 1; and a laser processing unit 20 that irradiates the first laser beam 22 to the wafer 1 held by the chuck table 6a.

The chuck stand 6a has a frame body 10a and a porous member 12a accommodated in the frame body 10a, and is supported by the base 4a. Furthermore, a jig 8a capable of holding the frame 11 of the frame unit 13 is disposed around the chuck table 6a. In addition, since the structure and structure of the chuck table 6a etc. are the same as those of the chuck table 6 of the spin coater 2, detailed description is abbreviate|omitted.

The laser processing unit 20 is equipped with: a laser oscillator (not shown), which can oscillate the laser with a wavelength absorbed by the wafer 1; and an optical system (not shown), which guides the laser emitted from the laser oscillator laser beam and focus it on wafer 1. For example, when the wafer 1 is a silicon wafer, the laser processing unit 20 can irradiate the wafer 1 with a laser beam with a wavelength of 355 nm.

The laser processing device 18 has: a processing feed unit, which can relatively move the chuck table 6a and the laser processing unit 20 in the processing feed direction; and an index feed unit, which can move the chuck table 6a and the laser processing unit The injection machining unit 20 relatively moves in an index feed direction perpendicular to the machining feed direction.

When dividing the wafer 1, first, the frame unit 13 is placed on the chuck table 6a, and the frame unit 13 is sucked and held by the chuck table 6a. Thereafter, the chuck table 6a is rotated so that the direction of the planned processing line 3 of the wafer 1 coincides with the processing feed direction.

Then, while operating the processing feeding unit to move the chuck table 6a and the laser processing unit 20 relatively in the processing feeding direction, the laser processing unit 20 is operated to irradiate the first processing line 3 on the wafer 1. A laser beam 22 . In this way, the processing groove 17 along the planned processing line 3 is formed on the wafer 1 by ablation. At this time, since the debris generated and scattered from the wafer 1 adheres to the protective film 15 , the debris does not adhere to the first surface 1 a side of the wafer 1 .

The irradiation conditions of the first laser beam 22 in the processing groove forming step S20 are set as follows, for example. However, the irradiation conditions of the first laser beam 22 are not limited thereto. Wavelength : 355nm Repetition frequency: 300kHz Average output: 7W Feed speed: 1000mm/second

After performing ablation processing along one planned processing line 3, the chuck table 6a and the laser processing unit 20 are relatively moved in the indexing feeding direction perpendicular to the processing feeding direction, and are moved along other planned processing lines 3 Similarly, wafer 1 is subjected to ablation processing. After forming the machining groove 17 along all the planned machining lines 3 in one direction, the chuck table 6a is rotated around an axis perpendicular to the holding surface, and the wafer is similarly moved along the planned machining lines 3 in the other direction. Circle 1 is processed by ablation.

For example, if the processing grooves 17 formed along all the planned processing lines 3 of the wafer 1 penetrate from the first surface (front) 1a to the second surface (back) 1b, the wafer 1 will be divided into individual wafers . However, the processing groove 17 is not limited thereto, and the processing groove 17 may not reach the second surface 1 b of the wafer 1 . In this case, the wafer 1 can be broken from the bottom of the processing tank 17 to the second surface 1 b by other additional processing.

In addition, when the processing groove 17 does not reach the second surface 1b of the wafer 1, at this point in time, the regions of the wafer 1 are not cut and separated from each other, so the positions of the regions do not deviate from each other. In this case, as will be described later, in the hardened area removal step S30, the areas to be irradiated when the second laser beam 24 is irradiated toward the wafer 1 are mutually fixed, so it is easy to align the second laser beam without deviation. 24 to the desired location on wafer 1. That is, the processing accuracy performed by the second laser beam 24 is improved.

Therefore, the need to inspect the processing state of the wafer 1 during processing is also reduced, and the number of times of inspection can be reduced to quickly complete the processing of the wafer 1 . That is, the fact that the processing groove 17 does not reach the second surface 1b of the wafer 1 is related to the improvement of the manufacturing efficiency of the wafer. In addition, in this case, finally, the wafer 1 will be divided along the processing groove 17 by applying an external force to the wafer 1 . However, the processing groove forming step S20 is not limited thereto, and the processing groove 17 can also reach the second surface 1b.

In addition, in the case where the processing groove 17 does not reach the second surface 1b of the wafer 1, an external force is applied in order to divide the wafer 1, for example, by pushing the adhesive film 9 radially in the inner side of the opening of the frame 11. The outer expansion is applied to the wafer 1 . If the adhesive film 9 is expanded radially outward, a radially outward force will be applied to the wafer 1 attached to the adhesive film 9 , and cracks will be generated at the bottom of the processing groove 17 to split the wafer 1 . At this time, the height position of the bottom of the processed groove 17 may be determined so that the cracks are generated.

Alternatively, the external force applied for splitting the wafer 1 may also be applied to the wafer 1 by pressing the wafer 1 from above with a roller having a length exceeding the diameter of the wafer 1, while placing the roller on the wafer 1. The wafer 1 is turned on the first side 1a. Alternatively, external force may also be applied to the wafer 1 by rotating the roller on the back side of the adhesive film 9 of the frame unit 13 while pressing the back surface of the adhesive film 9 from below.

Furthermore, the external force applied to split the wafer 1 may also be applied to the wafer 1 by further irradiation of a laser beam. That is, the laser beam is irradiated to the bottom of the processing tank 17 from the first surface 1 a side of the wafer 1 , and the laser beam is processed on the wafer 1 below the processing tank 17 . Thereby, the wafer 1 can be divided by forming a dividing groove reaching the second surface 1 b side of the wafer 1 . In addition, since the irradiated region of the laser beam at this time is far away from the resin layer 7, the resin layer 7 is less likely to undergo deterioration and hardening as described later due to irradiation of the laser beam.

Here, in the processing groove forming step S20, the first laser beam 22 can also be aligned in a direction parallel to the planned processing line 3 of the wafer 1 (processing feeding direction) and a vertical direction (indexing feeding direction). One or both of them diverge to irradiate the wafer 1 . In this case, because the branched first laser beam 22 is irradiated to each processing point one by one, it is different from the case of irradiating the unbranched powerful first laser beam 22 to each processing point. load becomes smaller. Also, the processing points are not overheated.

However, when the first laser beam 22 is branched and irradiated onto the wafer 1, the wafer 1 is also heated by the first laser beam 22, so that the resin layer 7 is Degenerates and hardens. FIG. 4(B) is an enlarged and schematic cross-sectional view of the wafer 1 on which the processing groove 17 is formed. FIG. 4(B) schematically shows the hardened region 7 a of the resin layer 7 and the altered region 15 a of the protective film 15 .

After the machining groove forming step S20, a hardened area removing step S30 of removing the hardened area 7a of the resin layer 7 that has been cured is performed. FIG. 5 is a schematic cross-sectional view showing step S30 of removing the hardened area. In addition, in FIG. 5 , illustration of the hardened region 7 a and the like is omitted. The step S30 of removing the hardened area can be carried out by the laser processing device 18 following the processing groove forming step S20 . However, the step S30 of removing the hardened area is not limited thereto, and may also be implemented by other laser processing devices.

In the hardened area removing step S30 , for example, the second laser beam 24 is irradiated to the area including the hardened area 7 a of the resin layer 7 under the condition that the resin layer 7 is less than the threshold value for hardening. The irradiation condition of the second laser beam 24 is determined in such a way that the energy density becomes lower than that of the first laser beam 22, but the second laser beam 24 can also be compared with the first laser beam in the processing groove forming step S20. The beam 22 is similarly irradiated onto the wafer 1 .

In addition, the irradiation conditions of the 2nd laser beam 24 in the hardened area|region removal process S30 are set as follows, for example. However, the irradiation conditions of the second laser beam 24 are not limited thereto. Wavelength : 355nm Repetition frequency: 300kHz Average output: 6W Feed speed: 1000mm/second

Here, in the hardened area removal step S30, the second laser beam 24 may be directed in one of a direction (processing feed direction) parallel to the processing plan line 3 of the wafer 1 (processing feed direction) and a vertical direction (index feed direction). Either or both diverge and are irradiated. In addition, in the hardened area removal step S30, the shape of the second laser beam 24 can be trimmed into an ellipse with different lengths of the long axis and short axis, a rectangle with different lengths of the long side and short side, or a shape with four sides of equal length. square to illuminate wafer 1.

In addition, the long axis of the elliptical second laser beam 24, the long side of the rectangular second laser beam 24, or one side of the square second laser beam 24 can be oriented perpendicular to the planned processing line 3. In the state of the direction, the second laser beam 24 is irradiated to the wafer 1 . In addition, the second laser beam 24 may be branched and irradiated in one or both of a direction parallel to the line to be processed 3 of the wafer 1 and a direction perpendicular to it.

FIG. 6(A) is a perspective view schematically showing each branched component 26 of the branched second laser beam 24 in an example. In addition, in FIG. 6(A), each branch component 26 is described by a solid line for convenience of description. In the example shown in FIG. 6(A), the second laser beam 24 diverges in a direction (X-axis direction in FIG. 6(A) ) parallel to the line 3 to be processed. Then, each branched component 26 of the second laser beam 24 is trimmed into a rectangular shape, and the long side 28 longer than its short side 30 is oriented in a direction perpendicular to the processing line 3 (Y in FIG. 6(A) axis direction).

For example, in the hardened region removing step S30 , the wafer 1 may be irradiated with the second laser beam 24 having a wider width than the processing groove 17 formed on the wafer 1 in the processing groove forming step S20 . That is, the long side 28 of each rectangular branch component 26 of the second laser beam 24 is preferably longer than the width of the processing groove 17 . Alternatively, the major axis of each branch component of the ellipse of the second laser beam 24 is preferably longer than the width of the processing groove 17 .

Then, the second laser beam 24 is preferably irradiated to the crystal in such a manner that the two hardened regions 7a of the resin layer 7 formed on both sides of the processing groove 17 are accommodated between one end and the other end of the long side 28. Circle 1. That is, the long side 28 is preferably set to a length greater than the distance between the outer edge of the hardened region 7a formed on one side of the processing groove 17 and the outer edge of the hardened region 7a formed on the other side of the processing groove 17. the distance between.

In this case, if the second laser beam 24 is irradiated to the hardened regions 7 a on both sides of the processed groove 17 along the processed groove 17 , the hardened regions 7 a can be removed. 8(A) is an enlarged and schematic cross-sectional view of the wafer 1 from which the cured region 7a of the resin layer 7 has been removed. Here, the second laser beam 24 can be irradiated to the uncured area of the resin layer 7 adjacent to the hardened area 7 a in a manner to surely remove the hardened area 7 a, and can be partially destroyed by the second laser beam 24 . Remove unhardened areas thoroughly.

Here, regarding the irradiation conditions of the first laser beam 22 irradiated to the wafer 1 in the process groove forming step S20 and the second laser beam 24 irradiated to the wafer 1 in the hardened area removal step S30 Differences are explained.

For example, the first laser beam 22 is preferably a Gaussian beam whose beam intensity distribution in the irradiated area becomes a Gaussian distribution. The Gaussian beam has a high beam intensity in the center of the irradiated area, and can be used to form a deep processing groove 17 . On the other hand, the intensity distribution of the second laser beam 24 in the irradiated area is preferably a more uniform flat-hat beam. The top-hat beam has a wide tolerance range for variations in irradiation positions, and it is easy to reliably remove the hardened region 7a from the uppermost end to the lowermost end.

The laser processing unit 20 preferably has a beam shaper (laser beam shaper) that converts a Gaussian beam into a flat-hat beam, and the second laser beam 24 can be irradiated to the wafer 1 through the beam shaper. The beam shaper is, for example, a DoE (Diffractive Optical Element, diffractive optical element) or a homogenizer.

In addition, the width of the cured region 7a formed in the processing groove forming step S20 varies depending on the irradiation conditions of the first laser beam 22 or the materials and thicknesses of the wafer 1, the resin layer 7 and the protective film 15, and the like. Therefore, the wafer 1 can be observed to obtain the width of the hardened region 7 a after the processing groove forming step S20 , and the length of the long side 28 of the second laser beam 24 can be determined according to the obtained finding.

In addition, if the irradiation conditions of the first laser beam 22 or the materials and thicknesses of the wafer 1 , the resin layer 7 , and the protective film 15 are constant, the width of the cured region 7 a is also substantially constant. Therefore, when the same wafer 1 is repeatedly processed under the same processing conditions to manufacture wafers, it is not necessary to observe the wafer 1 every time to determine the length of the long side 28 of the second laser beam 24 . In hardened area removal step S30 , wafer 1 may be irradiated with second laser beam 24 whose shape is trimmed so that long side 28 becomes a derived predetermined length.

6(B) is a perspective view schematically showing each branched component 32 of the branched second laser beam 24 in another example. In addition, in FIG. 6(B), each branch component 32 is described with a solid line for convenience of description. Each branched component 32 of the second laser beam 24 is trimmed into a rectangular shape, and the long side 37 that is longer than the short side faces the direction perpendicular to the line 3 to be processed.

In addition, in the example shown in FIG. 6(B), the second laser beam 24 is divided into a plurality of beams in a direction parallel to the processing line 3 (X-axis direction in FIG. 6(B) ). The direction perpendicular to the schedule line 3 (the Y-axis direction in FIG. 6(B) ) diverges into two.

The interval 36 between the branched components 32 divided into two in the vertical direction of the planned processing line 3 may be, for example, less than the width of the processing groove 17 formed on the wafer 1 . Then, the long sides 37 of the rectangular branched components 32 of the second laser beam 24 are preferably longer than the respective widths of the hardened regions 7 a formed on both sides of the processing groove 17 .

In the hardened region removal step S30, each hardened region 7a of the resin layer 7 formed on both sides of the processed groove 17 formed on the wafer 1 in the processed groove forming step S20 can be irradiated with two divided regions. second laser beam 24 . More specifically, one of the hardened regions 7a may be irradiated with the first of the split second laser beams 24, and the other of the hardened regions 7a on the opposite side across the processing groove 17 may be irradiated with the second laser beam. The second of the two laser beams 24 .

In the wafer manufacturing method of this embodiment, chips or processing chips are generated when the processing groove forming step S20 and the hardened region removing step S30 are performed, and these chips are scattered toward the first surface 1a side of the wafer 1 and adhere to the wafer 1. protective film15. Then, after the hardened area removal step S30, the protective film removal step S40 of removing the protective film 15 formed on the first surface 1a of the wafer 1 is implemented, and chips, processing chips and the protective film 15 are removed from the wafer 1 remove.

FIG. 7 is a schematic cross-sectional view showing step S40 of removing the protective film. The protective film removing step S40 can be implemented by the cleaning device 38 that supplies the cleaning water 42 to the frame unit 13 including the wafer 1 . The cleaning device 38 includes: a chuck table 6b that suction-holds the wafer 1 through the adhesive film; and a cleaning water supply nozzle 40 that supplies cleaning water 42 to the wafer 1 held by the chuck table 6b.

The chuck stand 6b has a frame body 10b and a porous member 12b housed in the frame body 10b, and is supported by the stand 4b. Furthermore, a jig 8b capable of holding the frame 11 of the frame unit 13 is disposed around the chuck table 6b.

A not-shown rotational drive source such as a motor is connected to the base 4b, and when this rotational drive source is operated, the chuck table 6b can be rotated around a rotational axis perpendicular to the upper surface. In addition, since the structure and structure of the chuck table 6b etc. are the same as the chuck table 6 of the spin coater 2, detailed description is abbreviate|omitted.

The cleaning water supply nozzle 40 has a discharge port that can move back and forth on a track that passes above the center of the upper surface of the chuck table 6b, and supplies pure water or the like to clean the first surface 1a of the wafer 1 held by the chuck table 6b. Water 42 for cleaning. In addition, high-pressure gas may be mixed into the cleaning water 42 supplied from the cleaning water supply nozzle 40 to the wafer 1, and the wafer 1 may be cleaned by a mixed fluid of pure water and high-pressure gas.

In the protective film removal step S40, the frame unit 13 is carried into the cleaning device 38 and placed on the chuck table 6b, the frame 11 is held by the clamper 8b, and the wafer 1 is sucked and held by the chuck table 6b through the adhesive film 9. Then, while the discharge port of the washing water supply nozzle 40 is moved back and forth on a predetermined track, the rotary drive source is operated to rotate the chuck table 6b around the rotary shaft at high speed. Then, the cleaning water is sprayed from the cleaning water supply nozzle 40 onto the first surface 1 a of the wafer 1 .

In this way, the first surface 1 a side of the wafer 1 is cleaned with the cleaning water 42 . Then, the water-soluble resin, that is, the protective film 15 is removed by washing water 42 , and debris, processing waste, and the like are also removed. Thereafter, the spraying of the cleaning water 42 from the cleaning water supply nozzle 40 is stopped, and the wafer 1 is dried. FIG. 8(B) is a schematic cross-sectional view of the wafer 1 from which the protective film 15 has been removed. When the wafer 1 is divided by the processing groove 17, a plurality of wafers each having a resin layer 7 on the upper surface can be obtained.

As described above, in the wafer manufacturing method of the present embodiment, the protective film 15 is formed on the first surface 1a of the wafer 1 having the resin layer 7 on the first surface 1a, and the first laser beam 22 is irradiated, and the This wafer 1 is divided. At this time, although the hardened region 7a is formed in the resin layer 7, this hardened region 7a is removed later, and the protective film 15 is removed from the 1st surface 1a.

Therefore, the hardened region 7 a of the resin layer 7 hardened by the first laser beam 22 does not remain in the wafer obtained by dividing the wafer 1 . Therefore, when the obtained plurality of wafers are laminated and bonded by thermocompression, the resin layer 7 will be appropriately stretched and bubbles will not remain inside. Therefore, no wafer defect due to the hardened region 7a occurs in the obtained laminated wafer.

In addition, this invention is not limited to description of each said embodiment, It can change variously and can implement. For example, in the above-mentioned embodiment, in the hardened area removal step S30, although the second laser beam 24 is irradiated to the hardened area 7a of the resin layer 7 to remove the hardened area 7a, one aspect of the present invention Not limited to this. That is, in the hardened area removing step S30 , the hardened area 7 a of the resin layer 7 may also be removed from the wafer 1 by other methods. Next, a modified example of the hardened area removal step S30 will be described.

FIG. 9 is a cross-sectional view schematically showing step S30 of removing the hardened region in a modified example. In the hardened area removing step S30 of the modified example, the hardened area 7 a of the resin layer 7 is removed by cutting it with the annular cutting blade 50 . Cutting of the hardened area 7a is performed by a cutting device 44 shown in FIG. 9 . The dicing device 44 includes: a chuck table 6c that attracts and holds the wafer 1; and a dicing unit 46 that cuts the wafer 1 held by the chuck table 6c.

The chuck stand 6c has a frame body 10c and a porous member 12c accommodated in the frame body 10c, and is supported by a stand 4c. Furthermore, a jig 8c capable of holding the frame 11 of the frame unit 13 is disposed around the chuck table 6c. In addition, since the structure and structure of the chuck table 6c etc. are the same as the chuck table 6 of the spin coater 2, etc., detailed description is abbreviate|omitted.

The cutting device 44 is equipped with: a processing feeding unit that can relatively move the chuck table 6c and the cutting unit 46 in the processing feeding direction; The indexing feed direction perpendicular to the machining feed direction moves relative to each other.

The cutting unit 46 of the cutting device 44 includes: a main shaft 48 along the index feeding direction; and a cutting blade 50 fixed to the front end of the main shaft 48 . A rotational drive source such as a motor is connected to the base end side of the main shaft 48 , and when the rotational drive source is operated, the cutting blade 50 rotates around the main shaft 48 as an axis.

The cutting blade 50 includes: an annular base 52 formed of a metal material such as aluminum; and an annular grindstone portion 54 fixed to the outer periphery of the base 52 . The grinding stone portion 54 is composed of abrasive grains formed of diamond or the like and a bonding material for dispersing and fixing the abrasive grains. When the cutting blade 50 is rotated and the grinding stone portion 54 is brought into contact with the workpiece, the workpiece is cut.

Here, the blade thickness of the dicing blade 50 (thickness of the whetstone portion 54 ) mounted on the front end of the spindle 48 is preferably larger than the width of the processing groove 17 formed on the wafer 1 in the processing groove forming step S20 . Furthermore, the cutting blade is preferably in such a manner that it can cut the whole area of the hardened region 7a of the resin layer 7 formed on both sides of the processed groove 17, which is smaller than the outer edge of the hardened region 7a on one side of the processed groove 17 and the other. The distance between the outer edges of the hardened region 7a on one side is greater for the blade thickness.

When cutting the hardened area 7a, first, the frame unit 13 is placed on the chuck table 6c, and the frame unit 13 is sucked and held by the chuck table 6c. Thereafter, the chuck table 6c is rotated so that the direction of the planned processing line 3 of the wafer 1 coincides with the processing feed direction.

Then, the grinding stone portion 54 of the dicing blade 50 is positioned above the extension line of the processing groove 17 formed on the wafer 1, and the dicing blade 50 is rotated at a predetermined rotational speed. Then, the cutting unit 46 is lowered so that the lower end of the grindstone portion 54 is positioned at the height position of the lower end of the resin layer 7 . Thereafter, the processing feeding unit is operated to relatively move the chuck table 6c and the cutting unit 46 in the processing feeding direction, and the cutting blade 50 is cut into the hardened area 7a of the resin layer 7 to remove the hardened area 7a.

After cutting the hardened area 7a along one line 3 to be processed, the chuck table 6c and the cutting unit 46 are moved in the index feed direction, and the hardened area 7a of the resin layer 7 is similarly cut along the other line 3 to be processed. After the hardened area 7a is removed along the entire planned line 3 in one direction, the chuck table 6c is rotated, and the hardened area 7a is similarly cut along the planned line 3 in the other direction. Thereby, all the cured regions 7 a of the resin layer 7 of the wafer 1 can be removed.

Furthermore, in the case of performing the hardened region removing step S30 by cutting by the dicing blade 50 , the hardened regions 7 a of the resin layer 7 formed on both sides of the processing groove 17 may also be individually removed. In this case, the blade thickness of the cutting blade 50 is preferably larger than the width of each hardened region 7 a formed on both sides of the processing groove 17 . In this way, the hardened area removing step S30 can also be performed by cutting by the cutting blade 50 .

In addition, in the above-mentioned embodiment, the case where the resin layer 7 functioning as NCF is provided on the first surface 1a side of the wafer 1 and the hardened region 7a formed in the resin layer 7 is removed is described. An aspect of the invention is not limited thereto. That is, the resin layer 7 provided on the first surface 1 a side of the wafer 1 may not be NCF.

For example, on the first surface 1a side of the wafer 1, the resin layer 7 may be provided for other purposes. Then, when the wafer 1 is divided into wafers by ablation processing, the resin layer 7 may be partially heated and degenerated, and degenerated regions may be formed in the resin layer 7 remaining on the wafer. For example, there are cases where the resin layer 7 is partially discolored due to the influence of heat caused by the ablation process, and the appearance of the wafers formed by dividing the wafer 1 is deteriorated.

Therefore, the degenerated area of the resin layer 7 can also be removed by the second laser beam 24 or the like. That is, the degenerated area of the resin layer 7 is removed by the above-described step described as the hardened area removal step S30. In this case, the hardened region removing step S30 can be re-named as a degenerated region removing step, and the cured region 7 a of the resin layer 7 can be re-named as a degenerated region.

In addition, in the above-mentioned embodiment, although the case where the element 5 is formed on the first surface 1 a side of the wafer 1 on which the resin layer 7 is disposed has been described, an aspect of the present invention is not limited thereto. That is, the element 5 may also be provided on the second surface 1b side. In this case, the first surface 1a of the wafer 1 is referred to as the back surface, and the second surface 1b is referred to as the front surface. In this case, the hardened area 7a formed in the resin layer 7 when the wafer 1 is irradiated with the first laser beam 22 from the first surface 1a side can also be removed by the hardened area removing step S30.

That is, the method of manufacturing a wafer according to one aspect of the present invention can be widely applied to any method of manufacturing a wafer including the process of arranging, by ablation processing, the surface on the side irradiated with a laser beam. A process of dividing the wafer 1 with the resin layer 7 .

In addition, the structure, method, etc. of the said embodiment can be changed suitably and implemented unless it deviates from the objective range of this invention.

1: Wafer 1a: first side 1b: Second side 2: Spin coater 3: Processing scheduled line 4,4a,4b,4c: Pedestal 5: Components 6,6a,6b,6c: chuck table 7: resin layer 7a: hardened area 8,8a,8b,8c: Fixtures 9: Film 10, 10a, 10b, 10c: frame 11: frame 12, 12a, 12b, 12c: porous member 13:Frame unit 14: Liquid resin supply nozzle 15: Protective film 15a: metamorphic area 16: liquid resin 17: Processing groove 18:Laser processing device 20:Laser processing unit 22,24: Laser Beam 26,32: divergent components 28,37: long side 30: short side 38: Cleaning device 40: Cleaning water supply nozzle 42: washing water 44: Cutting device 46: Cutting unit 48:Spindle 50: cutting blade 52: Abutment 54: Millstone department

FIG. 1 is a perspective view schematically showing a wafer having a resin layer on a first surface. Fig. 2 is a cross-sectional view schematically showing a step of forming a protective film. Fig. 3 is a cross-sectional view schematically showing a step of forming a processing groove. FIG. 4(A) is an enlarged and schematic cross-sectional view of a wafer on which a protective film is disposed, and FIG. 4(B) is an enlarged and schematic cross-sectional view of a wafer on which a processing groove is formed. Fig. 5 is a cross-sectional view schematically showing a hardened area removal step. Figure 6(A) is a perspective view schematically showing a laser beam diverging in a direction parallel to the planned processing line, and Figure 6(B) is a schematic representation of a laser beam diverging in a direction parallel to and perpendicular to the planned processing line Stereoscopic view of a beam of light. Fig. 7 is a cross-sectional view schematically showing a protective film removal step. 8(A) is an enlarged and schematic cross-sectional view of the wafer from which the hardened region of the resin layer has been removed, and FIG. 8(B) is an enlarged and schematic cross-sectional view of the wafer from which the protective film has been removed. Fig. 9 is a cross-sectional view schematically showing a modified example of the hardened region removal step. FIG. 10 is a flow chart showing the flow of each step in the wafer manufacturing method.

S10: protective film forming step

S20: processing groove forming step

S30: Hardened area removal step

S40: Protective film removal step

Claims (13)

A method of manufacturing a wafer, which divides a wafer having a resin layer on a first surface along a line to be processed to manufacture the wafer, and is characterized in that it comprises: a protective film forming step of forming a protective film on the first surface; a processing groove forming step of irradiating the wafer with a first laser beam having an absorbing wavelength from the first surface side along the processing plan line after the protective film forming step, and The circle forms the machining groove; a hardened area removing step of removing the hardened area of the resin layer which has been hardened after the processing groove forming step; and a protective film removing step of removing the protective film formed on the first surface after the hardened area removing step, And, individual wafers are formed by dividing the wafer along the processing grooves. The method for manufacturing a wafer as claimed in item 1, wherein, In the hardened area removing step, the hardened area is removed by irradiating a second laser beam to an area including the hardened area of the resin layer. The method for manufacturing a wafer as claimed in item 2, wherein, The energy density of the second laser beam is lower than the energy density of the first laser beam. The method for manufacturing a wafer as claimed in claim 2 or 3, wherein, The first laser beam is a Gaussian beam, and the second laser beam is a top-hat beam. The method for manufacturing a wafer as claimed in claim 2 or 3, wherein, In the hardened area removing step, the wafer is irradiated with the second laser beam having a width wider than that of the processing groove. The method for manufacturing a wafer as claimed in claim 2 or 3, wherein, In the step of removing the hardened area, the shape of the second laser beam is trimmed into an ellipse with different lengths of the long axis and short axis, a rectangle with different lengths of the long side and short side, or a square with four sides of equal length. The wafer is irradiated with the second laser beam in a state where the long axis, the long side or one of the sides is facing a direction perpendicular to the planned processing line. The method for manufacturing a wafer as claimed in claim 2 or 3, wherein, In the step of removing the hardened area, the second laser beam is irradiated by branching in one or both of a direction parallel to the processing plan line of the wafer and a direction perpendicular to it. The method for manufacturing a wafer as claimed in claim 2 or 3, wherein, In the hardened area removing step, the second laser beam is irradiated to the area including the hardened area of the resin layer under a condition smaller than a threshold value at which the resin layer is hardened. The method for manufacturing a wafer as claimed in item 1, wherein, In the hardened area removing step, the hardened area of the resin layer is removed by cutting with a cutting blade. The method for manufacturing a wafer as claimed in item 1, wherein, In the processing groove forming step, the first laser beam is branched in one or both of a direction parallel to the planned processing line of the wafer and a direction perpendicular to the wafer to irradiate the wafer. The method for manufacturing a wafer as claimed in item 1, wherein, The resin layer is NCF. The method for manufacturing a wafer as claimed in item 1, wherein, The protective film has a thickness of 5 μm or more. The method for manufacturing a wafer as claimed in item 1, wherein, the processing groove formed in the processing groove forming step does not reach the second surface of the wafer parallel to the first surface, The wafer is divided along the processing groove by applying an external force to the wafer.

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