JP2018190858A - Wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve chip division productivity and also to improve the number of obtained chips when dividing a wafer in which a TEG is formed on a street into chips by plasma dicing.SOLUTION: A method for processing a wafer in which a TEGa is formed on a street comprises: a protection film forming step of forming a protection film J made of a water-soluble resin on a rear surface Wb of a wafer W; a laser processing step of removing a projection film J at a position corresponding to a street S by irradiating the wafer W from the rear surface Wb side of the wafer with a laser beam of a wavelength having absorbability to the projection film J along the street S after performing the protection film forming step; a plasma processing step of applying plasma processing along the street S by plasma-etching the wafer from the rear surface Wb of the wafer W as the protection film J as a mask after performing the laser processing step; and a removing step of removing a residual part TEGb of the TEG by spraying a jetted product P into the residual part TEGb after performing the plasma processing step.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a method for processing a wafer having a plurality of intersecting streets and having TEGs formed on the streets.

  When a small chip wafer is divided into chips, plasma etching is used to divide the wafer into individual chips in order to improve productivity and street reduction (narrowing the street width (cut width)). Plasma dicing is effective (see, for example, Patent Document 1).

JP, 2006-021448, A

However, if the wafer has a TEG (an evaluation element made of metal or the like) formed on the street, this TEG cannot be divided by plasma dicing, and the productivity in dividing into chips becomes low. The number of pieces taken will not be sufficient.
Therefore, when a wafer having a TEG formed on a street is divided into chips by plasma dicing, there is a problem in that productivity in dividing into chips is improved and the number of chips taken is improved.

  The present invention for solving the above problems is a method for processing a wafer having a plurality of intersecting streets and having TEGs formed on the streets, and forming a protective film made of a water-soluble resin on the back surface of the wafer. After carrying out the protective film forming step and the protective film forming step, a laser beam having a wavelength that absorbs the protective film is irradiated from the back side of the wafer along the street to correspond to the street A laser processing step for removing the protective film at a position; and a plasma processing step for performing plasma processing along the street by performing plasma etching from the back surface of the wafer using the protective film as a mask after performing the laser processing step. After performing the plasma processing step, a removal step for removing the remaining portion by spraying a spray to the remaining portion of the TEG. And flop, a machining method with a.

  In the processing method according to the present invention, first, a water-soluble protective film is formed on the back surface of the wafer, and then plasma dicing is applied to the wafer from the back surface of the wafer. Furthermore, the remaining part of the TEG remaining on the front side of the wafer is removed with a projectile to produce a chip, which improves the productivity in dividing the wafer into chips as compared to the conventional method and reduces the number of chips to be taken. It becomes possible to improve.

It is a perspective view which shows an example of a wafer. It is sectional drawing which shows the state which forms the protective film which consists of water-soluble resin on the back surface of a wafer using a protective film formation apparatus. It is sectional drawing which shows the state which has irradiated the laser beam of the wavelength which has an absorptivity with respect to a protective film from the back surface side of a wafer along a street, and removed the protective film of the position corresponding to a street. It is sectional drawing which shows a part of wafer from which the protective film of the position corresponding to a street was removed. It is sectional drawing which shows an example of the plasma etching apparatus which performs a plasma etching on a wafer. It is sectional drawing which shows a part of wafer with the remaining part of TEG remaining on the street. It is sectional drawing which shows the state which wash | cleans and removes the protective film of a wafer. It is sectional drawing which shows the state which sprays the injection material to the remaining part of TEG of a wafer, and removes the remaining part.

  A wafer W shown in FIG. 1 is a silicon wafer having a circular outer shape, for example, and is set so that a plurality of streets S are orthogonal to the surface Wa of the wafer W. The devices D are formed in the lattice-like regions partitioned by the streets S, respectively. On the street S, a TEG (Test Element Group) a composed of a metal such as aluminum or copper and combined with a transistor, a resistor, or the like is formed at a predetermined interval. TEGa is electrically connected to the device D through a wiring layer (not shown) made of metal or the like. This wiring layer is also disposed in a region between the device D and TEGa. In FIG. 1, the TEGa has a rectangular shape and is provided at the center in the width direction of the street S, but is not limited thereto, and TEGs having various shapes and arrangements are used. A notch N for identifying the crystal orientation is formed on the outer peripheral edge of the wafer W so as to be recessed radially inward toward the center of the wafer W.

  In the following, each step of the processing method when the wafer processing method according to the present invention is carried out to produce a chip including the device D from the wafer W shown in FIG. 1 will be described.

(1) Protective film formation step First, a protective film made of a water-soluble resin is formed on the back surface Wb of the wafer W. In this protective film formation step, for example, a protective film is formed using the protective film forming apparatus 4 shown in FIG.
When the protective film is formed, as shown in FIG. 2, the wafer W has a protective tape T1 having a diameter larger than that of the wafer W attached to the surface Wa, and the outer peripheral portion of the adhesive surface of the protective tape T1 is an annular frame. It will be in the state stuck on F1. Then, the wafer W with the back surface Wb exposed upward is supported by the annular frame F1 via the protective tape T1, so that it can be handled by the annular frame F1. It is preferable that the annular frame F1 and the protective tape T1 have resistance to an etching gas (for example, SF ₆ gas or C ₄ F ₈ gas) used in a later plasma processing step. That is, for example, the annular frame F1 is made of SUS, and the protective tape T1 is made of polyolefin or the like.

  The protective film forming apparatus 4 includes, for example, a holding table 40 that holds the wafer W, a rotating means 42 that rotates the holding table 40, and a bottomed cylindrical casing 44 that has a circular opening on the upper end side. Yes.

  For example, the holding table 40 has a circular outer shape and includes a holding surface 40a made of a porous member or the like and communicating with a suction source. Around the holding table 40, for example, four fixing clamps 401 for fixing the annular frame F1 (for example, only two are illustrated) are equally disposed. The holding table 40 can move up and down. When the wafer W is placed, the holding table 40 is raised and positioned at the loading / unloading height position of the wafer W, and a liquid protective film agent is applied to the sucked and held wafer W. Is applied at a coating height position in the casing 44.

  The rotating means 42 disposed on the lower side of the holding table 40 includes a spindle 420 which is fixed at the upper end on the bottom surface side of the holding table 40 and can be rotated around a vertical axis, a motor and the like, and a lower end of the spindle 420. And a rotational drive source 421 connected to the side. When the rotation driving source 421 rotates the spindle 420, the holding table 40 also rotates.

  The holding table 40 is accommodated in the internal space of the casing 44. The casing 44 stands from an outer wall 440 that surrounds the holding table 40, a bottom plate 441 that is integrally connected to the lower portion of the outer wall 440 and has an opening through which the spindle 420 is inserted, and an inner peripheral edge of the opening of the bottom plate 441. It is comprised from the inner wall 442 to provide, and is supported by the leg part 443 by which the end was fixed to the baseplate 441. A circular cover between the lower surface of the holding table 40 and the upper end surface of the inner wall 442 of the casing 44 that is inserted into the spindle 420 and prevents foreign matter from entering the gap between the spindle 420 and the opening of the bottom plate 441. A member 444 is provided.

  In the casing 44, a nozzle 45 for dropping a protective film agent on the wafer W sucked and held by the holding surface 40a is disposed. The nozzle 45 is erected from the bottom plate 441 of the casing 44, and the outer shape is substantially L-shaped in a side view. The ejection port 450 formed at the tip of the nozzle 45 opens toward the holding surface 40 a of the holding table 40. The nozzle 45 can turn around the axis in the Z-axis direction, and can move the ejection port 450 from above the holding table 40 to the retracted position.

  The nozzle 45 communicates with a protective film agent supply source 47 storing a protective film agent made of a water-soluble resin (for example, polyvinyl pyrrolidone or polyvinyl alcohol) via a pipe 47a and a rotary joint (not shown). The protective film agent stored in the protective film agent supply source 47 is, for example, HogoMax manufactured by DISCO Corporation.

  The wafer W supported by the annular frame F1 is placed on the holding surface 40a of the holding table 40 with the protective tape T1 side down, so that the back surface Wb of the wafer W is exposed upward. Become. Then, the suction force generated by a suction source (not shown) is transmitted to the holding surface 40a, whereby the wafer W is sucked and held by the holding table 40. Further, the annular frame F <b> 1 is fixed by each fixing clamp 401. Then, the holding table 40 holding the wafer W is lowered to the coating height position in the casing 44. Further, the nozzle 45 pivots and the injection port 450 is positioned above the center of the back surface Wb of the wafer W.

  Next, the protective film agent supply source 47 supplies the protective film agent to the nozzle 45, and a predetermined amount of the protective film agent is dropped from the injection port 450 onto the center of the back surface Wb of the wafer W. Then, by rotating the holding table 40 at a predetermined speed, the dropped protective film agent flows from the center side to the outer peripheral side of the back surface Wb of the wafer W by centrifugal force and reaches the entire surface, and has a substantially uniform thickness. A protective film J is formed on the back surface Wb of the wafer W. Thereafter, the rotation is continued and the protective film J is rotated and dried.

(2) Laser Processing Step The wafer W having the protective film J formed on the back surface Wb is transferred to the laser processing apparatus 1 shown in FIG. The laser processing apparatus 1 includes, for example, a chuck table 10 that sucks and holds a wafer W, and a laser beam irradiation unit that irradiates a protective film J of the wafer W held on the chuck table 10 with a laser beam having an absorptive wavelength. 11 and a control means (not shown) for controlling the apparatus.
A control means including a storage element such as a CPU and a memory is electrically connected to the chuck table 10 and the laser beam irradiation means 11, and under the control of the control means, the rotation operation of the chuck table 10 and the laser beam irradiation. The movement operation of the means 11 is controlled.

  The chuck table 10 has, for example, a circular outer shape, and sucks and holds the wafer W on a horizontal holding surface 10a made of a porous member or the like. The chuck table 10 can be rotated around the axis in the vertical direction (Z-axis direction) and can be reciprocated in the X-axis direction by a processing feed means (not shown). For example, four (only two in the illustrated example) fixed clamps 100 are equally disposed on the outer periphery of the chuck table 10. The fixed clamp 100 including the clamping plate 100a and the clamping table 100b is configured such that the clamping plate 100a can be rotated about a rotation shaft 100c by a spring (not shown), and the lower surface of the clamping plate 100a and the upper surface of the clamping table 100b. The annular frame F1 can be sandwiched between the two.

The laser beam irradiation means 11 can be reciprocated in the Y-axis direction by an index feed means (not shown) composed of a ball screw, a motor, etc., and a laser beam oscillated from the laser beam oscillator 119 and having an absorption property to the protective film J The laser beam is accurately condensed at a predetermined height position of the wafer W held by the chuck table 10 by allowing light to enter the condensing lens 111a inside the condenser 111 through a transmission optical system such as an optical fiber. Can be irradiated. The focal point position of the laser beam condensed by the condenser 111 can be adjusted in a direction (Z-axis direction) perpendicular to the holding surface 10a of the chuck table 10 by a focal point position adjusting unit (not shown). It has become.
The chuck table 10 can be reciprocated in the X-axis direction and can also be reciprocated in the Y-axis direction. The chuck table 10 can be moved in the X-axis direction or the Y-axis with respect to the fixed laser beam irradiation means 11. It is good also as what moves relatively to a direction.

  In the laser processing step, the wafer W supported by the annular frame F1 is sucked and held by the chuck table 10 with the protective film J facing upward. Further, the annular frame F <b> 1 is fixed by each fixing clamp 100. Next, the wafer W held on the chuck table 10 is sent in the −X direction (forward direction, rear side of the paper), and one street S serving as a reference for irradiating the protective film J with the laser beam is detected. The The detection of the street S is executed by, for example, the street position detection means 12 shown in FIG.

  For example, the street position detection means 12 includes a diameter of the wafer W, a distance between a notch N (not shown in FIG. 3) formed on the outer peripheral edge of the wafer W and a plurality of streets S formed on the surface Wa of the wafer W. A pattern design value of the wafer W indicating information such as intervals between the plurality of streets S is stored.

  The street position detection unit 12 includes, for example, a notch detection unit 120 that is disposed above the chuck table 10 and detects a notch N of the wafer W. The notch detection unit 120 includes, for example, a light reflection type optical sensor, and the outer periphery of the wafer W passes through the detection region of the notch detection unit 120 as the chuck table 10 that holds the wafer W rotates. The notch N formed on the outer peripheral edge of the wafer W can be detected. Note that the notch detection unit 120 may be configured by a camera, and the notch detection unit 120 may detect the notch N of the wafer W by performing image processing on a captured image captured by the camera.

  When the notch N of the wafer W is detected by the notch detection unit 120, the street position detection means 12 detects the position of the notch N that becomes the reference position from the detected notch N and the pattern design value of the wafer W stored in advance. The relative position of one street S with respect to can be detected. Next, the street position detection means 12 sends a detection signal about the position of one street S with respect to the position of the notch N serving as the reference position to a control means (not shown). Upon receiving this detection signal, the control means rotates the chuck table 10 by a predetermined angle to position the notch N at a predetermined coordinate position, so that the street S serving as a reference for irradiating the protective film J with the laser beam is a predetermined street. Adjust so that it is at the coordinate position. Specifically, for example, an imaginary line passing through the center of the wafer W and the notch N is parallel to the X-axis direction, and the notch N is on the −X direction side (the back side in FIG. 3). The chuck table 10 holding the wafer W is rotated so as to be positioned. As a result, for example, one street S serving as a reference when the protective film J is first irradiated with the laser beam is in a state extending in parallel to the X-axis direction, and the one street S The Y-axis coordinate position is recognized.

  The detection of the street S is not limited to the present embodiment. For example, when the protective film J has a property of transmitting infrared rays, the wafer W is placed near the laser beam irradiation unit 11. An alignment means for detecting the street S may be provided. In each device D of the wafer W, the same circuit pattern is formed at the same position. One pattern having a characteristic shape among the circuit patterns formed on the surface of each device D is selected as a target pattern to be detected during alignment, and the alignment means captures the target pattern in advance. Remembered images. The alignment unit includes an infrared irradiation unit that irradiates infrared rays, an infrared camera that includes an optical system that captures infrared rays, and an image sensor (infrared CCD) that outputs electrical signals corresponding to the infrared rays. Detecting the street S of the front surface Wa of the wafer W with high accuracy by image processing such as pattern matching based on the captured image showing the target pattern on the device D acquired through the camera from the back surface Wb side. Can do.

  As the position of the street S serving as a reference for laser beam irradiation is detected, the laser beam irradiation means 11 is indexed and fed in the Y-axis direction, and the position of the street S and the condenser 111 in the Y-axis direction. Matching is done. The alignment is performed so that the center line of the street S is located immediately below the condenser lens 111a of the condenser 111. Next, the condensing point position of the laser beam condensed by the condensing lens 111 a is positioned at the height position of the protective film J. Then, the laser beam oscillator 119 oscillates a laser beam having an absorptivity with respect to the protective film J, and the laser beam is focused on the protective film J of the wafer W held by the chuck table 10 and irradiated.

  While irradiating the protective film J along the street S from the back surface Wb of the wafer W, the chuck table 10 is moved in the −X direction (forward direction) at a predetermined processing feed rate. As shown in FIG. 3, the protective film J located at the position corresponding to the street S, that is, above the reference street S is evaporated and removed.

  The position where the wafer W advances in the −X direction to a predetermined position in the X-axis direction where the laser beam is completely irradiated on the back surface Wb of the wafer W on the position corresponding to one street S, and the position corresponds to one street S. When the protective film J is removed, the laser beam irradiation is stopped and the processing feed of the wafer W in the −X direction is once stopped. Next, the laser beam irradiation means 11 is indexed and fed in the + Y direction, and the alignment in the Y-axis direction between the street S located next to the street S that becomes the reference in the laser beam irradiation in the forward direction and the condenser 111 is performed. I do. This alignment is performed based on the pattern design value of the wafer W. After alignment, the wafer W is processed and fed in the + X direction (reverse direction), and the protective film J at a position corresponding to one street S from the back surface Wb side of the wafer W is irradiated in the same manner as the irradiation of the laser beam in the forward direction. A laser beam is irradiated on the surface. By sequentially irradiating the same laser beam, the laser beam is irradiated to the protective film J from the back surface Wb side of the wafer W along all the streets S extending in the X-axis direction. The protective film J is removed.

  Further, when the same laser beam irradiation is performed after the chuck table 10 is rotated 90 degrees, the protective film J corresponding to the street S is removed along all the streets S in the vertical and horizontal directions as shown in FIG. be able to.

(3) Plasma processing step After performing the laser processing step, the wafer W is transferred to the plasma etching apparatus 9 shown in FIG.

  The plasma etching apparatus 9 shown in FIG. 5 includes an electrostatic chuck 90 that holds a wafer W, a gas ejection head 91 that ejects gas, and a chamber 92 that houses the electrostatic chuck 90 and the gas ejection head 91 therein. ing.

  For example, an electrostatic chuck 90 formed of a ceramic such as alumina or a dielectric 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 disposed in parallel with the holding surface 90a of the electrostatic chuck 90, and the electrode 901 is aligned. The device 94a is connected to a bias high-frequency power source 95a. For example, the electrostatic chuck 90 is not limited to a monopolar electrostatic chuck as in the present embodiment, and may be a so-called bipolar electrostatic chuck.

  A gas diffusion space 910 is formed inside a gas ejection head 91 that is disposed at the top of the chamber 92 via a bearing 919 so as to be movable up and down. A gas introduction port 911 communicates with the upper portion of the gas diffusion space 910. A plurality of gas discharge ports 912 communicate with the lower part of the gas diffusion space 910. The lower end of each gas discharge port 912 is opened toward the holding surface 90 a of the electrostatic chuck 90.

A gas supply unit 93 is connected to the gas inlet 911. The gas supply unit 93 stores, for example, a fluorine-based gas such as SF ₆ , CF ₄ , C ₂ F ₆ , C ₂ F ₄ as an etching gas.

  A high-frequency power source 95 is connected to the gas ejection head 91 via a matching device 94. By supplying high-frequency power from the high-frequency power source 95 to the gas ejection head 91 via the matching unit 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 gas discharge amount, 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.
On the side of the chamber 92, a loading / unloading port 920 for loading / unloading the wafer W and a gate valve 921 for opening / closing the loading / unloading port 920 are provided.

  Using the plasma etching apparatus 9, plasma etching is performed on the wafer W along the street S from the back surface Wb using the protective film J as a mask. First, the gate valve 921 is opened, the wafer W is loaded into the chamber 92 from the loading / unloading port 920, and the wafer W is placed on the holding surface 90a of the electrostatic chuck 90 with the protective film J side facing up. 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 a sealed space of a predetermined pressure.

The gas ejection head 91 is lowered to a predetermined height position, and in this state, an etching gas mainly composed of, for example, SF ₆ 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 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, thereby converting the etching gas into plasma. In parallel with this, a voltage is applied to the electrode 901 from the bias high-frequency power source 95a to generate a dielectric polarization phenomenon between the holding surface 90a of the electrostatic chuck 90 and the wafer W, and electrostatic adsorption due to charge polarization. The wafer W is sucked and held on the holding surface 90a by the force.

  The plasma etching gas hardly etches the protective film J acting as a mask, and the corresponding portion of the wafer W on the street S where the protective film J is not formed is different from the back surface Wb side in the −Z direction. Isotropic etching. Therefore, lattice-shaped etching grooves along the streets S are formed on the wafer W.

The plasma etching gas does not etch a wiring layer (not shown) which is made of a TEGa metal portion and a metal or the like and electrically connects the TEGa and the device D. Therefore, as shown in FIG. 6, plasma etching is terminated after plasma etching is performed until the remaining portion of TEGb TEGb and a wiring layer (not shown) are exposed at the bottom of the etching groove. That is, the introduction of the etching gas or the like into the chamber 92 shown in FIG. 5 and the supply of the 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. The etching gas is not present in the chamber 92. As a result, as shown in FIG. 6, the wafer W is in a state where the TEGA remaining portion TEGb remains on the street S. Further, on the street S of the wafer W, the wiring layer connected to the device D corresponding to the remaining portion TEGb of TEGa remains.
Note that the plasma processing step is not limited to the above-described form performed by plasma etching using SF6 gas alone, and plasma etching using SF6 gas and protective film deposition (deposition) on the groove sidewalls and the like by C4F8 are alternately repeated. It may be performed by the Bosch method.

(Cleaning removal of protective film)
For example, the wafer W that has been subjected to the plasma etching process is transferred to the protective film forming apparatus 4 as shown in FIG. (1) The protective film forming apparatus 4 used in the protective film forming step plays a role of forming a protective film J made of a water-soluble resin on the back surface Wb of the wafer W, as well as a protective film from above the back surface Wb of the wafer W. It is possible to play a role of cleaning and removing J. Note that the protective film J may be cleaned and removed from the wafer W by a cleaning apparatus different from the protective film forming apparatus 4.

For example, as shown in FIG. 7, a cleaning water nozzle 46 that sprays cleaning water onto the protective film J of the wafer W sucked and held by the holding surface 40 a is disposed in the casing 44. The washing water nozzle 46 is erected from the bottom plate 441 of the casing 44, and the outer shape is substantially L-shaped in a side view. The injection port 460 formed at the tip portion of the cleaning water nozzle 46 opens toward the holding surface 40 a of the holding table 40. The washing water nozzle 46 can turn around the axis in the Z-axis direction, and can move the ejection port 460 from above the holding table 40 to the retracted position.
The cleaning water nozzle 46 communicates with a cleaning water supply source 48 that stores cleaning water (for example, pure water) via a pipe 48a and a rotary joint (not shown).

  First, the wafer W is sucked and held by the holding table 40 with the protective film J exposed upward. Further, the annular frame F <b> 1 is fixed by each fixing clamp 401. After the holding table 40 for sucking and holding the wafer W is positioned at the spray height position in the casing 44, the cleaning water nozzle 46 pivots and the spray port 460 is sucked and held by the holding table 40 above the central region of the wafer W. Positioned on. Then, the cleaning water supply source 48 supplies the cleaning water to the cleaning water nozzle 46, and the cleaning water is jetted from the injection port 460 toward the center of the protective film J. The washing water may be jetted at a high pressure. Further, the holding table 40 rotates around the axis in the Z-axis direction.

  As a result, the protective film J made of water-soluble resin is dissolved by the cleaning water, and flows on the back surface Wb of the wafer W together with the cleaning water by the centrifugal force generated by the rotation of the holding table 40. It flows down to the bottom plate 441 of 44. Therefore, the protective film J is removed from the back surface Wb of the wafer W.

(Transfer of wafer to protective sheet)
In the wafer W from which the protective film J has been removed from the entire back surface Wb, for example, the protective tape T1 is peeled off from the front surface Wa, and the support by the annular frame F1 is released. Further, as shown in FIG. 8, the wafer W has a protective sheet T2 having a diameter larger than that of the wafer W attached to the back surface Wb, and the outer peripheral portion of the adhesive surface of the protective sheet T2 is attached to the ring frame F2. Become. Then, the wafer W with the surface Wa exposed upward is supported by the ring frame F2 via the protective sheet T2, so that it can be handled by the ring frame F2.

(4) Removal Step The wafer W that is ready to be handled by the ring frame F2 is transferred to the removal device 3 that removes the remaining TEGb TEGb on the street S, for example, as shown in FIG. The removal apparatus 3 includes, for example, a holding table 30 that holds the wafer W, a rotating unit 32 that rotates the holding table 30, and a bottomed cylindrical casing 34 that has a circular opening on the upper end side.

The circular holding table 30 is movable up and down and includes a holding surface 30a communicating with a suction source. Around the holding table 30, for example, four fixing clamps 301 for fixing the ring frame F <b> 2 (only two in the illustrated example are illustrated) are arranged equally.
The rotating means 32 disposed below the holding table 30 rotates the holding table 30 fixed to the spindle 320 when the motor 321 rotates the spindle 320.

  The casing 34 that houses the holding table 30 includes an outer wall 340 that surrounds the holding table 30, a bottom plate 341 that is integrally connected to a lower portion of the outer wall 340 and has an opening through which the spindle 320 is inserted, and a bottom plate 341. It is comprised from the inner side wall 342 standing from the inner periphery of opening. A circular cover member 344 is disposed between the lower surface of the holding table 30 and the upper end surface of the inner wall 342 of the casing 34.

  In the casing 34, there is disposed an injection nozzle 35 that can inject, for example, powdered dry ice (solid carbon dioxide particles) with air pressure onto the wafer W sucked and held by the holding surface 30a. The injection nozzle 35 is erected from the bottom plate 341 of the casing 34, and the outer shape is substantially L-shaped in a side view, and the injection port 350 formed at the distal end portion faces the holding surface 30 a of the holding table 30. It is open. The injection nozzle 35 can turn around the axis in the Z-axis direction, and can move the injection port 350 from above the holding table 30 to the retracted position.

  The injection nozzle 35 is connected to a carbon dioxide supply source 36 in which liquid carbon dioxide is stored, via a pipe 36a and a rotary joint (not shown). The injection nozzle 35 is connected to an air supply source 37 that stores compressed air (compressed air) via a pipe 37a and a rotary joint (not shown).

  When injecting the spray onto the remaining portion TEGb of the TEG of the wafer W, the wafer W is placed on the holding surface 30a of the holding table 30 positioned at the carry-in height position with the surface Wa facing upward. W is sucked and held by the holding table 30. Further, the ring frame F <b> 2 is clamped and fixed by each fixing clamp 301. Next, the holding table 30 holding the wafer W is lowered to the working height position in the casing 34. Further, the spray nozzle 35 rotates and the spray port 350 is positioned above the center of the wafer W.

  Liquid carbon dioxide is supplied from the carbon dioxide supply source 36 to the injection nozzle 35, and air is supplied from the air supply source 37 to the injection nozzle 35. The liquid carbon dioxide supplied from the carbon dioxide supply source 36 and the air supplied from the air supply source 37 are mixed at high pressure in the injection nozzle 35, and the injection P is directed downward from the injection port 350 of the injection nozzle 35. As a result, the temperature of the liquid carbon dioxide falls below the freezing point due to adiabatic expansion, and extremely fine powdery dry ice (solid carbon dioxide particles) P1 is generated. When the spray P containing the powdery dry ice P1 collides with the wafer W, the dry ice P1 is deformed and crushed and sublimated to carbon dioxide gas.

  Further, the injection nozzle 35 that injects the injection product P rotates so as to reciprocate around the axis in the Z-axis direction at a predetermined angle above the wafer W. Further, the holding table 30 rotates, and the spray P including the dry ice P1 is sprayed from the spray port 350 of the spray nozzle 35 over the entire surface Wa of the wafer W. When the injection P including dry ice P1 collides with the remaining portion TEGb of the TEG on the street S, the remaining portion TEGb of the TEG is blown off from the street S by the vaporization expansion of the dry ice P1, and is removed from the wafer W. By the rotation of the holding table 30, it is blown out toward the outer side in the radial direction and eliminated. Similarly, a wiring layer (not shown) corresponding to the remaining portion TEGb of the TEG is also removed from the wafer W. The wafer W can be divided into individual chips each provided with the device D by spraying the ejected material P onto the wafer W for a predetermined time.

In addition, when injecting the ejected matter P onto the wafer W, for example, a captured image showing the street S of the wafer W is formed, and the coordinate position of the street S of the wafer W is detected from this captured image, The remaining part TEGb of the TEG may be removed from the street S one line at a time by spraying the ejected matter P linearly along the detected street S toward the remaining part TEGb of the TEG.
Further, the transfer of the wafer W onto the protective sheet T2 is not performed, and the ejected matter P is sprayed onto the wafer W from the back surface Wb side of the wafer W, so that the remaining portion TEGb of the TEG is removed from the street S. Good.

  Further, the injection nozzle 35 shown in FIG. 8 may be configured to inject high-pressure water instead of injecting the injection P including the powdered dry ice P1. That is, the injection nozzle 35 is connected to a water supply source that stores water (for example, pure water) instead of the carbon dioxide supply source 36 via the pipe 36a. In this case, high-pressure water is sprayed from the injection port 350 toward the wafer W at a pressure (for example, 100 MPa to 300 MPa) at which the wafer W is not damaged or the chips C are not scattered, and the remaining portion of the TEG is generated with this high-pressure water. TEGb can be removed from the street S.

  In the processing method according to the present invention, first, a water-soluble protective film J is formed on the back surface Wb of the wafer W, and then plasma dicing is applied to the wafer W from the back surface Wb of the wafer W. Furthermore, by removing the remaining part TEGb of the TEG remaining on the front surface Wa side of the wafer W with the spray P, the productivity in dividing the wafer into chips is improved and the number of chips is improved as compared with the prior art. It becomes possible to make it.

  As described above, in the wafer processing method according to the present invention, a series of processes from the formation of the protective film J to the removal of the remaining TEGb of the TEG are performed in a state where the wafer W is supported by the annular frame. Excellent handling of W. Further, since the number of times of tape transfer of the wafer W can be reduced, work efficiency can be improved.

W: Wafer Wa: Wafer surface Wb: Wafer back surface N: Notch S: Street D: Device F1: Ring frame T1: Protective tape T2: Protective sheet TEGa: TEG TEGb: Remaining part of TEG 4: Protective film forming apparatus 40 : Holding table 40a: Holding surface 401: Fixed clamp 42: Rotating means 420: Spindle 421: Rotation drive source 44: Casing 440: Outer wall 441: Bottom plate 442: Inner wall 443: Leg
444: Cover member 45: Nozzle 450: Injection port 47: Protective film agent supply source 46: Cleaning water nozzle 460: Injection port 48: Cleaning water supply source 1: Laser processing device 10: Chuck table 10a: Holding surface 100: Fixed clamp DESCRIPTION OF SYMBOLS 11: Laser beam irradiation means 111: Condenser 111a: Condensing lens 119: Laser beam oscillator 12: Street position detection means 120: Notch detection part 9: Plasma etching apparatus 90: Electrostatic chuck 90a: Electrostatic chuck holding surface 900: Support member 901: Electrode 91: Gas ejection head 910: Gas diffusion space 911: Gas inlet 912: Gas outlet
92: Chamber 920: Loading / unloading port 921: Gate valve 93: Gas supply unit 94, 94a: Matching unit 95, 95a: High frequency power source, bias high frequency power source 96: Exhaust port 97: Exhaust device 3: Removal device 30: Holding table 32: Rotating means
34: casing 35: injection nozzle 350: injection port 36: carbon dioxide supply source 37: air supply source P: propellant P1: solid carbon dioxide particles

Claims (1)

A method of processing a wafer having a plurality of intersecting streets and a TEG formed on the streets,
A protective film forming step for forming a protective film made of a water-soluble resin on the back surface of the wafer;
After performing the protective film forming step, the protective film at a position corresponding to the street is irradiated by irradiating a laser beam of a wavelength having an absorption property to the protective film from the back side of the wafer along the street. A laser processing step to be removed;
A plasma processing step of performing plasma processing along the street by performing plasma etching from the back surface of the wafer using the protective film as a mask after performing the laser processing step;
And a removing step of removing the remaining portion by spraying a spray onto the remaining portion of the TEG after performing the plasma processing step.

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