JP6912254B2 - Processing method - Google Patents

Description

The present invention relates to a method for processing a workpiece in which a film is formed on the back surface of a plate-shaped object and a plurality of scheduled division lines are set.

When a plate-like object having a particularly ductile film such as a metal film or a resin film is cut with a cutting blade, the cutting blade is clogged with the film. Therefore, a method of removing the film with a laser beam has been proposed in advance before cutting (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-42526

However, there is a problem that debris is generated when the film is removed by a laser beam, and the manufacturing cost is also increased because the film is generally processed by using an expensive laser processing apparatus.

Therefore, when processing a film-formed plate-shaped workpiece, it is possible to process the workpiece without causing clogging of the cutting blade and without using a laser machining apparatus. There are challenges.

In the present invention for solving the above problems, a film is formed on the back surface of a plate-shaped object, and a workpiece having a plurality of intersecting scheduled division lines set on the front surface is divided along the planned division line. Te a processing method for forming a plurality of chips, a groove having a cross-sectional V-shaped tapered along converting said cross scheduled line from the surface of the workpiece, are alternately repeated and the protective film deposition to dry etching and trench sidewall At the same time, a groove forming step formed by changing the timing of switching the treatment time between the dry etching and the protective film deposition to change the inclination of the side wall of the groove, and before or after performing the groove forming step. After performing the expanding sheet attaching step of attaching the expanding sheet to the back surface of the work piece, the expanding sheet attaching step, and the groove forming step, the expanding sheet is expanded and the film is formed along the groove. It is a processing method including an expansion step of applying an external force to the coating film and a pickup step of picking up a chip from the expanding sheet after performing the expansion step.

In the expansion step, the membrane may be divided along the groove.

Alternatively, the expansion step may form a division starting point along the groove with respect to the film, and the film may be divided along the groove in the pickup step.

Processing method in accordance with the invention, the groove having a cross-sectional V-shaped tapered along section scheduled line from the surface of the workpiece, with alternating protective layer deposited to dry etching and trench sidewall, and the dry etching A groove forming step formed by changing the inclination of the side wall of the groove by changing the timing of switching the treatment time with the protective film deposition, and expanding on the back surface of the workpiece before or after performing the groove forming step. After performing the expanding sheet attaching step, the expanding sheet attaching step, and the groove forming step of attaching the sheet, the expanding sheet is expanded to apply an external force to the film along the groove, and the expansion step is performed. Since it is equipped with a pickup step for picking up the chip from the expanding sheet after the execution, the film is expanded or picked up without using a laser processing device and without causing clogging due to the film on the cutting blade. Can be divided to produce chips from the workpiece. In the groove forming step, dry etching and protective film deposition on the groove side wall are alternately repeated, and the timing for switching the processing time between dry etching and protective film deposition is changed to obtain a tapered groove having a V-shaped cross section. It is possible to form a groove while changing the inclination of the side wall so as to have a desired inclination.

It is sectional drawing which shows an example of the workpiece. It is sectional drawing which shows an example of the plasma etching apparatus for forming a groove in a work piece. It is sectional drawing which enlarges and shows an example of the groove formed in the workpiece. It is sectional drawing which shows the state which set the workpiece which was attached to the expanding sheet and supported by an annular frame in the expanding apparatus. It is sectional drawing which shows the state which divides a membrane along a groove by expanding an expanding sheet by an expanding apparatus. FIG. 5 is an enlarged cross-sectional view showing a chip including a divided film and a device. It is sectional drawing which shows the state which the chip is picked up from an expanding sheet. It is sectional drawing which shows the state which formed the division start point along the groove with respect to a membrane by expanding an expand sheet by an expand device. It is sectional drawing which shows a part of the workpiece which formed the division start point along the groove in the film. It is sectional drawing which shows the state which picked up a chip from an expanding sheet while dividing a membrane.

The workpiece W shown in FIG. 1 is, for example, a circular semiconductor wafer including a plate-shaped object W1 made of silicon, and a plurality of divisions are formed on the surface of the plate-shaped object W1, that is, the surface W1a of the workpiece W. Scheduled lines S are set to be orthogonal to each other. Then, the device D is formed in each of the grid-like regions partitioned by the scheduled division line S. In FIG. 1, a film W2 having a uniform thickness (for example, 0.5 μm to 10 μm) made of a metal such as copper and nickel and acting as an electrode is formed on the back surface W1b of the plate-shaped object W1 facing the −Z direction side. It is formed. The exposed surface of the film W2 is the back surface W2b of the workpiece W. The configuration of the workpiece W is not limited to the example shown in this embodiment. For example, the plate-shaped material W1 may be composed of gallium arsenide, sapphire, gallium nitride, silicon carbide, or the like in addition to silicon, and the film W2 is not a metal film, for example, DAF (Die Attach Film) or DBF ( A resin film having a thickness of about 5 μm to 30 μm, such as Die Backside Film), may be used.

Hereinafter, each step of the processing method when the processing method according to the present invention is carried out to divide the workpiece W shown in FIG. 1 into a chip including the device D will be described.

(1) Expanding sheet attaching step For example, first, the expanding sheet T1 is attached to the back surface W2b of the workpiece W shown in FIG. The expanding sheet T1 is, for example, a disk-shaped sheet having an outer diameter larger than the outer diameter of the workpiece W, and has appropriate elasticity with respect to a mechanical external force. For example, the annular frame F1 is positioned with respect to the workpiece W so that the center of the workpiece W placed on the sticking table (not shown) and the center of the opening of the annular frame F1 substantially coincide with each other. Then, the expanding sheet T1 is pressed against the back surface W2b of the workpiece W by a press roller or the like on the pasting table and is pasted. At the same time, by attaching the outer peripheral portion of the adhesive surface T1a of the expanding sheet T1 to the annular frame F1, the workpiece W is in a state of being supported by the annular frame F1 via the expanding sheet T1, and the annular frame F1 is moved. It becomes possible to handle through. After the expanding sheet T1 is first attached only to the workpiece W with a press roller or the like, the workpiece W is appropriately positioned with respect to the annular frame F1 and the expanding sheet T1 is attached to the annular frame F1. You may. As a result, the workpiece W can be handled via the annular frame F1. The center of the workpiece W is in a state of substantially matching the center of the opening of the annular frame F1. The present expanding sheet sticking step may be carried out after carrying out the groove forming step described later.

(2) Grooving Step The workpiece W to which the expanding sheet T1 is attached is conveyed to the plasma etching apparatus 9 shown in FIG. The plasma etching apparatus 9 shown in FIG. 2 includes an electrostatic chuck 90 that holds the workpiece W, a gas ejection head 91 that ejects gas, and a chamber 92 that internally houses the electrostatic chuck 90 and the gas ejection head 91. It has. The plasma etching apparatus used in the groove forming step is an inductively coupled plasma system in which high-frequency power for generating plasma is applied to the dielectric coil and the etching gas is turned into plasma by interaction with the magnetic field formed in the dielectric coil. It may be an etching apparatus.

For example, the electrostatic chuck 90 formed of a ceramic such as alumina or a dielectric material such as titanium oxide is supported from below by a support member 900. Inside the electrostatic chuck 90, an electrode (metal plate) 901 that generates an electric charge when a voltage is applied is arranged in parallel with the holding surface 90a of the electrostatic chuck 90, and the electrodes 901 are matched. It is connected to the device 94a and the bias high frequency power supply 95a. For example, the electrostatic chuck 90 is not limited to the unipolar electrostatic chuck as in the present embodiment, and may be a so-called bipolar electrostatic chuck.
For example, a cooling water passage (not shown) through which cooling water passes and circulates is formed inside the electrostatic chuck 90, and a cooling water supply means communicates with the cooling water passage. The cooling water supply means causes the cooling water to flow into the cooling water passage, and the cooling water cools the electrostatic chuck 90 from the inside to a predetermined temperature. Further, heat transfer of He gas or the like is performed between the holding surface 90a of the electrostatic chuck 90 and the workpiece W held by the holding surface 90a in order to improve the heat absorption efficiency of the cooling water with respect to the workpiece W. The gas is designed to flow at a predetermined pressure.

A gas diffusion space 910 is provided inside the gas ejection head 91 which is vertically arranged in the upper part of the chamber 92 via a bearing 919, and a gas introduction port 911 communicates with the upper part of the gas diffusion space 910. However, a plurality of gas discharge ports 912 communicate with each other in the lower part of the gas diffusion space 910. The lower end of each gas discharge port 912 opens toward the holding surface 90a of the electrostatic chuck 90.

A gas supply unit 93 is connected to the gas introduction port 911. The gas supply unit 93 stores fluorine-based gases such as _{SF 6} , CF ₄ , C ₂ F ₆ , C ₂ F _{4, and} C ₄ F _{8 as etching gases.}

A high frequency power supply 95 is connected to the gas ejection head 91 via a matching device 94. By supplying high-frequency power from the high-frequency power supply 95 to the gas ejection head 91 via the matching device 94, the etching gas discharged from the gas discharge port 912 can be turned into plasma. The plasma etching apparatus 9 includes a control unit (not shown), and conditions such as a gas discharge amount, a time, and high-frequency power are controlled under the control of the control unit.

An exhaust port 96 is formed at the bottom of the chamber 92, and an exhaust device 97 is connected to the exhaust port 96. By operating the exhaust device 97, the inside of the chamber 92 can be depressurized to a predetermined degree of vacuum.
A carry-in outlet 920 for carrying in and out the workpiece W and a gate valve 921 for opening and closing the carry-in outlet 920 are provided on the side portion of the chamber 92.

When the workpiece W is subjected to plasma etching to form a groove, each device D (not shown in FIG. 2) is in a state of being protected by the resist film R. That is, for example, after a positive resist solution is applied to the surface W1a of the workpiece W to form a resist film having a uniform thickness on the surface W1a, ultraviolet light is irradiated only to the scheduled division line S for exposure. By developing the work piece W to be processed later, the line S to be divided is exposed and the device D is protected by the resist film R.

When the expanding sheet attaching step (1) is carried out after the main groove forming step is carried out, the workpiece W transported to the plasma etching apparatus 9 has a tape or a hard plate on its back surface W2b. It is attached as a protective member, and the back surface W2b is protected by the protective member.

The groove is formed by, for example, a Bosch method in which plasma etching with _{SF 6} gas and protective film deposition (deposition) on the groove side wall and the like _{with C 4} F _{8 are alternately repeated.}
First, the gate valve 921 is opened, the workpiece W is carried into the chamber 92 from the carry-in outlet 920, and the workpiece W is placed on the holding surface 90a of the electrostatic chuck 90 with the surface W1a side facing upward. .. The gate valve 921 is closed, the inside of the chamber 92 is exhausted by the exhaust device 97, and the inside of the chamber 92 is made into a closed space having a predetermined pressure.
For example, the following processing conditions are set in the plasma etching apparatus 9 as common processing conditions at the time of plasma etching and the time of depositing the protective film, which will be described later.
High frequency power frequency of each high frequency power supply: 13.56MHz
Maintenance temperature of electrostatic chuck 90: 10 ° C
He gas pressure flowing between the electrostatic chuck 90 and the workpiece W: 2000 Pa

The gas ejection head 91 is lowered to a predetermined height position, and in that state, _{the etching gas mainly composed of SF 6} is supplied from the gas supply unit 93 to the gas diffusion space 910, and is ejected downward from the gas discharge port 912. Further, a high-frequency power is applied from the high-frequency power source 95 to the gas ejection head 91 to generate a high-frequency electric field between the gas ejection head 91 and the electrostatic chuck 90, causing a discharge in the etching gas to generate S or the etching gas. It is dissociated into radicals having F ions and unpaired electrons to form a plasma. In parallel with this, by applying high-frequency power from the bias high-frequency power source 95a to the electrode 901, a dielectric polarization phenomenon is generated between the holding surface 90a of the electrostatic chuck 90 and the workpiece W, and the electric charge is polarized. The workpiece W is attracted and held on the holding surface 90a by the electrostatic attraction force.

Due to the bias power applied to the electrostatic chuck 90, the etching gas turned into plasma is drawn into the workpiece W. Then, the plasmaized etching gas is etched downward on the planned division line S without etching each device D coated with the resist film R. Therefore, a grid-like groove M1 along the scheduled division line S shown in FIG. 3 is formed in the plate-shaped object W1.
An example of the processing conditions at the time of etching is, for example, the conditions shown below.
Applied power to gas ejection head 91: 2500W
Applied power to electrode 901: 150W
Etching gas type: SF ₆
Gas flow rate: 400 sccm
Internal pressure of chamber 92: 25 Pa
Etching time: 5 seconds

_{Next, the C 4} F ₈ gas is supplied from the gas supply unit 93 to the gas diffusion space 910 and ejected downward from the gas discharge port 912. Further, a high-frequency power is applied to the gas injection head 91 from the high frequency power supply 95, further by applying a high frequency electric power from the bias RF power supply 95a to the electrode _{901, C} 4 _{F 8} gas causing a discharge in C 4 _{F 8} gas Is turned into plasma, and a fluorocarbon film as a protective film is deposited on the side wall and the bottom surface of the groove M1 shown in FIG.
An example of the processing conditions at the time of depositing the protective film is, for example, the following conditions.
Applied power to gas ejection head 91: 2500W
Applied power to electrode 901: 50W
Gas type: C ₄ F ₈
Gas flow rate: 400 sccm
Internal pressure of chamber 92: 25 Pa
Etching time: 3 seconds

Next, the etching gas SF ₆ is supplied into the chamber 92 to generate a plasma discharge to turn the SF ₆ into plasma, the protective film on the bottom surface of the groove M1 is removed to expose the silicon, and the bottom surface of the groove M1 is etched. do. Then, the inclination of the side wall of the groove M1 to be formed is changed by changing the timing of switching the treatment time between etching and protective film deposition. For example, _{by gradually shortening the etching processing time by SF 6} , the etching region on the bottom surface of the groove M1 is narrowed by the protective film deposited on the side wall of the groove M1, and the cross-sectional shape is V as shown in FIG. The tapered groove M1 having a shape extends downward. Etching (5 seconds) and protective film deposition (3 seconds) are treated as one cycle, and for example, 50 cycles are carried out.

The plasma-ized etching gas does not etch the metal film W2. Therefore, as shown in FIG. 3, plasma etching is performed until the bottom of the groove M1 having a V-shaped cross section does not reach the inside of the film W2 and the surface W2a of the film W2 is exposed to the bottom of the groove M1 in an ultrafine linear shape. After that, plasma etching is completed. That is, the introduction of the etching gas or the like into the chamber 92 shown in FIG. 2 and the supply of high-frequency power to the gas ejection head 91 are stopped, and the etching gas in the chamber 92 is exhausted from the exhaust port 96 to the exhaust device 97. , It is assumed that there is no etching gas inside the chamber 92.
In addition, plasma etching may be performed until the plate-shaped object W1 remains at the bottom of the groove M1 shown in FIG. 3 with a small thickness as an etching remaining portion.

Next, the resist film R shown in FIG. 2 is removed from the surface W1a of the workpiece W. The resist film R is removed by, for example, a wet treatment using a predetermined chemical or an ashing (ashing) of the resist film R by a plasma etching apparatus 9.

(3-1) Embodiment 1 of the expansion step
After performing the groove forming step as described above, the expanding step T1 of the workpiece W in which the groove M1 is formed is expanded to apply an external force to the film W2 along the groove M1. Then, in the expansion step of the first embodiment, the film W2 is divided along the groove M1.

As shown in FIG. 4, the workpiece W in a state of being supported by the annular frame F1 is conveyed to the expanding device 5 via the expanding sheet T1. The expanding device 5 includes, for example, an annular table 50 having an outer diameter larger than the outer diameter of the expanding sheet T1, and the diameter of the opening 50c of the annular table 50 is formed to be smaller than the outer diameter of the expanding sheet T1. There is. For example, four fixed clamps 52 (only two are shown in the illustrated example) are evenly arranged on the outer peripheral portion of the annular table 50. The fixed clamp 52 is rotatable about a rotating shaft 52c by a spring or the like (not shown), and sandwiches the annular frame F1 and the expanding sheet T1 between the holding surface 50a of the annular table 50 and the lower surface of the fixed clamp 52. be able to.

A cylindrical expansion drum 53 is arranged in the opening 50c of the annular table 50 with a fixed height position, and the center of the annular table 50 and the center of the expansion drum 53 substantially coincide with each other. The outer diameter of the expansion drum 53 is formed to be smaller than the outer diameter of the expanding sheet T1 and larger than the outer diameter of the workpiece W.

The annular table 50 can be moved up and down by, for example, the annular table elevating means 55. The annular table elevating means 55 is, for example, an air cylinder, and includes a bottomed cylindrical cylinder tube 550 having a piston (not shown) inside, and a piston rod 551 inserted into the cylinder tube 550 and having one end attached to the piston. The other end of the piston rod 551 is fixed to the lower surface of the annular table 50. When air is supplied (or discharged) to the cylinder tube 550 and the internal pressure of the cylinder tube 550 changes, the piston rod 551 moves in the Z-axis direction and the annular table 50 moves in the Z-axis direction.

First, the annular frame F1 is placed on the holding surface 50a of the annular table 50 positioned at the reference height position via the expanding sheet T1. The fixed clamp 52 rotates, and the annular frame F1 and the expanding sheet T1 are clamped and fixed between the fixed clamp 52 and the holding surface 50a of the annular table 50. In this state, the holding surface 50a of the annular table 50 and the annular upper end surface of the expansion drum 53 are at the same height position, and the upper end surface of the expansion drum 53 is the inner peripheral edge of the annular frame F1 of the expanding sheet T1. The expanded sheet T1 comes into contact with the region between the outer peripheral edge of the workpiece W from the base material surface side (lower surface side in FIG. 4).

As shown in FIG. 5, the annular table elevating means 55 lowers the annular table 50 in the −Z direction to position the holding surface 50a of the annular table 50 at the expanding seat expansion position below the upper end surface of the expansion drum 53. .. As a result, the expansion drum 53 rises relative to the fixed clamp 52, and the expanding sheet T1 is pushed up by the upper end surface of the expansion drum 53 and expanded outward in the radial direction. The region along the groove M1 of the film W2 to which the expanding sheet T1 is attached is provided via the expanding sheet T1 because the cross section is exposed to the bottom of the V-shaped groove M1 in an ultrafine linear shape. It is easy to be divided by an external force (expansion force). Further, as compared with the case where a groove having a rectangular cross section is formed in the workpiece W by, for example, anisotropic etching, the width of the film W2 exposed at the bottom of the groove due to the groove M1 having a V-shaped cross section. Is narrowed, so that the divided portion of the film W2 is made more uniform. In the expansion step of the first embodiment, the magnitude of the external force applied to the membrane W2 via the expanding sheet T1 is adjusted by controlling the lowering position of the holding surface 50a of the annular table 50, and is shown in FIG. As described above, the film W2 is divided along the groove M1 to divide the workpiece W into the device D and the individual chips C including the divided film W2.

(4-1) Embodiment 1 of the pickup step
After performing the expansion step of the first embodiment as described above, the chip C is picked up from the expanding sheet T1. For example, in the case where the expanding sheet T1 is of a type whose adhesive strength is reduced by irradiation with ultraviolet rays, the expanding sheet T1 shown in FIG. 6 is irradiated with ultraviolet rays to adhere the adhesive surface T1a before picking up the chip C from the expanding sheet T1. Reduce power. Next, the chip C in a state of being supported by the annular frame F1 via the expanding sheet T1 is conveyed to, for example, the pickup device 8 shown in FIG. 7. The pickup device 8 is a needle 80 that fixes an annular frame F (not shown in FIG. 7) with a holding clamp or the like and can move up and down in the Z-axis direction. The tip C is picked up by suction-holding the place where C is lifted from the expanding sheet T1 by the suction pad 81.

(3-2) Embodiment 2 of the expansion step
(2) After carrying out the groove forming step, the expansion step of the present embodiment 2 may be carried out instead of the expansion step of the above-mentioned (3-1) embodiment 1. In the expansion step of the second embodiment, a division starting point along the groove M1 is formed with respect to the film W2.

First, as shown in FIG. 4, an annular frame F1 that supports the workpiece W via the expanding sheet T1 is placed on the holding surface 50a of the annular table 50 positioned at the reference height position. Next, the annular frame F1 and the expanding sheet T1 are sandwiched and fixed between the fixing clamp 52 and the holding surface 50a of the annular table 50. Next, as shown in FIG. 8, the annular table elevating means 55 lowers the annular table 50 in the −Z direction, so that the expansion drum 53 rises relative to the fixed clamp 52, and the expanding sheet T1 moves to the expansion drum. It is pushed up by the upper end surface of 53 and expanded outward in the radial direction. Further, the expanding sheet T1 is placed in a region along the groove M1 of the film W2 to which the expanding sheet T1 is attached, that is, in the film W2 whose cross section is exposed in an ultrafine linear shape on the bottom of the V-shaped groove M1. Expansion power is given through. Then, by controlling the lowering position of the holding surface 50a of the annular table 50, the magnitude of the external force applied to the film W2 via the expanding sheet T1 is adjusted, and as shown in FIG. 9, the film W2 is subjected to the magnitude of the external force. A division starting point W2d along the groove M1 is formed.

(4-2) Embodiment 2 of the pickup step
After carrying out the expansion step of the second embodiment as described above, the pickup step of the second embodiment is carried out in which the film W2 is divided along the groove M1 from the starting point W2d and the chip is picked up from the expanding sheet T1.

For example, in the case where the expanding sheet T1 is of a type in which the adhesive strength is reduced by irradiation with ultraviolet rays, the expanding sheet T1 shown in FIG. 9 is irradiated with ultraviolet rays to reduce the adhesive strength of the adhesive surface T1a, and then the groove M1 is formed in the film W2. The workpiece W on which the division starting point W2d is formed along the above is conveyed to the pickup device 8 shown in FIG. The pickup device 8 fixes the annular frame F (not shown in FIG. 10) with a clamp (not shown) or the like, and pushes up the tip C from below via the expanding sheet T1 with a needle 80 that can move up and down in the Z-axis direction. .. As a result, an external force due to pushing up is intensively applied to the division starting point W2d, and the film W2 is divided along the groove M1. Then, the place where the tip C is lifted from the expanding sheet T1 is sucked and held by the suction pad 81 to pick up the tip C.

The processing method according to the present invention includes a groove forming step of forming a groove M1 having a cross-section V shape along a planned division line S from the surface W1a of the workpiece W by dry etching, and before or before performing the groove forming step. After performing the expanding sheet attaching step of attaching the expanding sheet T1 to the back surface W2b of the workpiece W, the expanding sheet attaching step, and the groove forming step, the expanding sheet T1 is expanded along the groove M1. Since it is provided with an expansion step of applying an external force to the film W2 and a pickup step of picking up a chip from the expanding sheet T1 after performing the expansion step, a laser processing device is not used and the film is applied to the cutting blade. The film W2 can be divided to produce the chip C from the workpiece W without causing clogging due to W2.

For example, when the workpiece W is a wafer in which the number of chips that can be obtained by division increases due to the formation of more devices, that is, when each chip that can be manufactured is a wafer that becomes a smaller chip. Or, when the expanding sheet is made of a material that does not easily expand and contract, the film W2 may not be completely divided only by expanding the expanding sheet. Even in such a case, the division starting point W2d along the groove M1 is formed with respect to the film W2 in the expansion step of the second embodiment (3-2), and the film W2 is formed in the pickup step of the second embodiment (4-2). By dividing the film W2 along the groove M1, the film W2 can be reliably divided and the chip C can be produced from the workpiece W.

W: Work piece W1: Plate-like material W1a: Surface work piece S: Scheduled division line D: Device W1b: Back side of plate-like material W2: Membrane W2a: Surface surface of film W2b: Back side of work piece
T1: Expanding sheet T1a: Adhesive surface of expanding sheet F1: Circular frame M1: Groove 9: Plasma etching apparatus 90: Electrostatic chuck 90a: Holding surface of electrostatic chuck 900: Support member 901: Electrode 91: Gas ejection head 910: Gas diffusion space 911: Gas inlet 912: Gas outlet
92: Chamber 920: Carry-in / outlet 921: Gate valve 93: Gas supply unit 94, 94a: Matcher 95, 95a: High-frequency power supply, bias high-frequency power supply 96: Exhaust port 97: Exhaust device R: Resist film
5: Expanding device 50: Ring table 50a: Holding surface of ring table 50c: Ring table opening 52: Fixed clamp 53: Expansion drum 55: Ring table elevating means 550: Cylinder tube 551: Piston rod 8: Pickup device 80: Needle 81: Suction pad

Claims (3)

This is a processing method in which a film is formed on the back surface of a plate-shaped object and a plurality of intersecting scheduled division lines are set on the front surface to divide the workpiece along the scheduled division lines to form a plurality of chips. hand,
Processing a groove having a tapered cross-sectional V shape along converting said cross scheduled line from the surface of the workpiece, with alternating protective layer deposited to dry etching and trench sidewall, and the dry etching and the protective film deposition A groove forming step formed by changing the inclination of the side wall of the groove by changing the timing of switching the time, and
An expanding sheet attaching step of attaching an expanding sheet to the back surface of the workpiece before or after performing the groove forming step, and an expanding sheet attaching step.
After performing the expanding sheet attaching step and the groove forming step, an expansion step of expanding the expanding sheet and applying an external force to the film along the groove, and an expansion step.
A processing method including a pickup step for picking up chips from the expanding sheet after performing the expansion step. The processing method according to claim 1, wherein in the expansion step, the film is divided along the groove. In the expansion step, a division starting point along the groove is formed with respect to the membrane.
The processing method according to claim 1, wherein the film is divided along the groove in the pickup step.

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