JP2019212769A - Wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer processing method capable of performing plasma etching while suppressing costs. A wafer processing method divides a wafer along a dividing line. The wafer processing method includes a protective member arranging step ST1 in which an adhesive tape is arranged on the front surface side of the wafer, a cutting step ST2 in which a cutting groove is formed along the planned dividing line on the back surface side of the wafer, and a bottom of the cutting groove. Plasma etching step ST3 of removing the remaining portion of the wafer and dividing the wafer by the dividing grooves along the planned dividing line, and attaching the die attach film to the back surface of the wafer, attaching the expand tape, and peeling the adhesive tape. The replacement step ST7 and the die attachment film breaking step ST8 of cooling the die attachment film and then expanding the expanded tape to break the die attachment film along the individual devices are provided. [Selection diagram] Figure 2

Description

  The present invention relates to a wafer processing method, and more particularly to plasma dicing.

  It is known that a processing method using a cutting blade or a laser beam is applied in order to divide a semiconductor wafer made of a silicon substrate or the like into individual device chips. In these processing methods, the division lines (streets) are processed one by one to divide the wafer into device chips. Due to the recent miniaturization of electronic devices, the miniaturization and cost reduction of device chips have progressed, and many device chips having a size of less than 2 mm have been produced from device chips having a size exceeding 10 mm as in the past. . When manufacturing a device chip with a small size, the number of lines to be divided for one wafer increases dramatically, and the processing time for each line becomes longer.

  In view of this, a technique called plasma dicing has been developed in which all the division lines of a wafer are processed at once (for example, see Patent Document 1). The plasma dicing disclosed in Patent Document 1 removes the region shielded by the mask by plasma etching and performs processing in units of wafers, so that the processing time is dramatically increased even if the number of lines to be divided increases. There is an effect that it does not become long.

  However, in the plasma dicing disclosed in Patent Document 1, it is necessary to prepare a precise mask suitable for the division line of each wafer in order to accurately expose only the region to be removed by etching (for example, Patent Reference 2 and Patent Document 3).

JP 2006-114825 A JP 2013-055120 A JP 2014-199833 A

  However, in particular, the masks disclosed in Patent Document 2 and Patent Document 3 are costly and difficult problems compared to cutting and the like, such as suppression of manufacturing cost and manufacturing man-hours and establishment of a technique for aligning the mask. Was left.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a wafer processing method capable of performing plasma etching while suppressing cost.

  In order to solve the above-described problems and achieve the object, a wafer processing method according to the present invention divides a wafer having a plurality of devices formed on a surface along a predetermined dividing line dividing the plurality of devices. A method for processing a wafer, wherein a protection member is disposed on the front surface side of the wafer, and a cutting blade is cut on the back surface side of the wafer so that the cutting does not reach the surface of the wafer. A cutting step for forming a groove along the line to be divided, and a gas obtained by converting the wafer holding the protective member side by a chuck table into a plasma on the back surface side, and etching the remaining portion of the bottom of the cutting groove A plasma etching step of dividing the wafer by dividing grooves along the planned dividing line, and after performing the plasma etching step, Attaching a die attach film to the surface and attaching an expand tape, a reattaching step for peeling off the protective member from the surface of the wafer, and after performing the attaching step, the die attach film is cooled to expand and contract A die attach film breaking step of expanding the expanded tape after reducing the properties and breaking the die attach film along individual devices.

  In the wafer processing method, the wafer includes a substrate and a functional layer that is stacked on the surface of the substrate to form a device, and after the substrate is divided in the plasma etching step, Further, a functional layer cutting step of cutting the functional layer by irradiating the condensing point of the laser beam at the bottom of the dividing groove may be provided.

  The wafer processing method may include a finish grinding step for grinding the back surface of the wafer to a finished thickness after the plasma etching step.

  The wafer processing method may include a pre-grinding step for grinding the back surface of the wafer in advance before the plasma etching step.

  The wafer processing method of the present invention produces an effect that plasma etching can be performed while suppressing costs.

FIG. 1 is a perspective view illustrating an example of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a flowchart showing a flow of a wafer processing method according to the first embodiment. FIG. 3 is a side view partially showing a cutting step of the wafer processing method shown in FIG. 4 is a cross-sectional view of the main part of the wafer after the cutting step of the wafer processing method shown in FIG. FIG. 5 is a cross-sectional view showing the configuration of an etching apparatus used in the plasma etching step of the wafer processing method shown in FIG. 6 is a cross-sectional view of the main part of the wafer after the plasma etching step of the wafer processing method shown in FIG. FIG. 7 is a cross-sectional view showing a functional layer cutting step of the wafer processing method shown in FIG. FIG. 8 is a cross-sectional view of the main part of the wafer after the functional layer cutting step of the wafer processing method shown in FIG. FIG. 9 is a sectional side view showing a cleaning step of the wafer processing method shown in FIG. FIG. 10 is a side sectional view showing a finish grinding step of the wafer processing method shown in FIG. FIG. 11 is a cross-sectional view of a wafer showing a re-attaching step of the wafer processing method shown in FIG. FIG. 12 is a cross-sectional view showing a state in which the wafer is held in the expansion device in the die attach film breaking step of the wafer processing method shown in FIG. FIG. 13 is a cross-sectional view showing a state in which the die attach film is broken for each device in the die attach film breaking step of the wafer processing method shown in FIG. FIG. 14 is a flowchart showing a flow of a wafer processing method according to the second embodiment. FIG. 15 is a sectional side view showing a preliminary grinding step of the wafer processing method shown in FIG. FIG. 16 is a cross-sectional view of the main part of the wafer after the preliminary grinding step of the wafer processing method shown in FIG. FIG. 17 is a cross-sectional view of the main part of the wafer after the plasma etching step of the wafer processing method according to the third embodiment. FIG. 18 is a cross-sectional view showing a configuration of an etching apparatus used in the plasma etching step of the wafer processing method according to the fourth embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

[Embodiment 1]
A wafer processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view illustrating an example of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a flowchart showing a flow of a wafer processing method according to the first embodiment.

  The wafer processing method according to the first embodiment is a method of processing the wafer 1 shown in FIG. In the first embodiment, the wafer 1 is a disk-shaped semiconductor wafer or optical device wafer including a substrate 2 made of silicon, sapphire, gallium arsenide, or the like. As shown in FIG. 1, the wafer 1 includes a functional layer 4 laminated on the surface 3 of the substrate 2, and a plurality of devices 5 are formed on the surface 3 of the substrate 2. The functional layer 4 is composed of a low dielectric constant insulating film (Low-k film) made of an inorganic film such as SiOF or BSG (SiOB), or an organic film such as a polyimide or parylene polymer film. ing. The functional layer 4 is laminated on the surface 3 of the substrate 2 to constitute the device 5.

  The device 5 is formed in each region defined by a plurality of division lines 6 intersecting the surface 3. That is, the division planned line 6 defines a plurality of devices 5. The circuit constituting the device 5 is supported by the functional layer 4. In the first embodiment, the device 5 is smaller than the device divided from the wafer 1 by cutting, and has a size of about 1 mm × 1 mm, for example. Further, in the wafer 1, at least one of a metal film (not shown) and a TEG (Test Element Group) is formed on the surface 3 side of the substrate 2 in at least a part of the division line 6. The TEG is an evaluation element for finding out design and manufacturing problems occurring in the device 5.

  The wafer processing method according to the first embodiment is a method in which the wafer 1 is divided into individual devices 5 along the division line 6 and the devices 5 are thinned to a finished thickness of 100. As shown in FIG. 2, the wafer processing method includes a protective member disposing step ST1, a cutting step ST2, a plasma etching step ST3, a functional layer cutting step ST4, a cleaning step ST5, a finish grinding step ST6, It includes a pasting step ST7 and a die attach film breaking step ST8.

(Protective member placement step)
The protective member disposing step ST1 is a step of disposing an adhesive tape 200 as a protective member on the functional layer 4 side of the surface 3 of the substrate 2 of the wafer 1. In the first embodiment, as shown in FIG. 1, the protective member disposing step ST <b> 1 attaches an adhesive tape 200 having a diameter larger than that of the wafer 1 to the functional layer 4 side, and an annular frame 201 on the outer peripheral edge of the adhesive tape 200. Affix. In the first embodiment, the adhesive tape 200 is used as the protective member, but the protective member is not limited to the adhesive tape 200 in the present invention. The wafer processing method proceeds to the cutting step ST2 when the adhesive tape 200 is attached to the functional layer 4 side of the wafer 1.

(Cutting step)
FIG. 3 is a perspective view showing a cutting step of the wafer processing method shown in FIG. 4 is a cross-sectional view of the main part of the wafer after the cutting step of the wafer processing method shown in FIG.

  In the cutting step ST2, the cutting blade 12 of the cutting apparatus 10 shown in FIG. 3 is cut into the back surface 7 side of the substrate 2 of the wafer 1, and a cutting groove 300 having a depth that does not reach the front surface 3 of the wafer 1 is divided into lines 6 It is the step which forms along. In the first embodiment, in the cutting step ST2, as shown in FIG. 3, two cutting units 11 are provided, that is, a holding surface 14 of the chuck table 13 of a two-spindle dicer, a so-called facing dual type cutting device 10. Then, the functional layer 4 side of the wafer 1 is sucked and held via the adhesive tape 200. In the cutting step ST2, an infrared camera (not shown) of the cutting apparatus 10 images the back surface 7 of the wafer 1 and performs alignment for aligning the wafer 1 and the cutting blade 12 of each cutting unit 11.

  In the cutting step ST2, the cutting blade 12 is cut into the back surface 7 while relatively moving the wafer 1 and the cutting blade 12 of each cutting unit 11 along the scheduled dividing line 6, and the wafer 1 is moved toward the back surface 7 side. A cutting groove 300 is formed. The thickness of the cutting blade 12 (hereinafter referred to as reference numeral 12-1) of one cutting unit 11 (hereinafter referred to as reference numeral 11-1) of the pair of cutting units 11 of the cutting apparatus 10 used in the first embodiment is as follows. The thickness of the cutting blade 12 (hereinafter denoted by reference numeral 12-2) of the other cutting unit 11 (hereinafter denoted by reference numeral 11-2) is larger. In the cutting step ST2 of the first embodiment, the cutting blade 12-1 of one of the cutting units 11-1 is cut into the back surface 7 by a finishing thickness of 100 minutes, so that the first cutting groove 301 is formed on the back surface 7 of the wafer 1. . In the first embodiment, in the cutting step ST2, the cutting blade 12-1 of one cutting unit 11-1 is cut into the back surface 7 for a finishing thickness of 100 minutes. The cutting blade 12-1 may be cut into the back surface 7 to a depth shallower than the finished thickness 100. In short, the cutting blade 12-1 of one cutting unit 11-1 is finished on the back surface 7 with a finished thickness of 100 or less. It is desirable to cut the depth.

  In the cutting step ST <b> 2, after forming the first cutting groove 301, the cutting blade 12-2 of the other cutting unit 11-2 is cut into the groove bottom 303 of the first cutting groove 301, and from the first cutting groove 301. A thin second cutting groove 302 is formed in the groove bottom 303 of the first cutting groove 301. In the cutting step ST 2, the first cutting groove 301 and the second cutting groove 302 are formed, and the finished thickness 100 of the wafer 1 is exceeded on the back surface 7 of the wafer 1 and the depth does not reach the functional layer 4, that is, the front surface 3. The cutting groove 300 is formed, and the penetration of the etching gas converted into plasma in the plasma etching step ST3 into the cutting groove 300 is promoted. In the first embodiment, the cutting groove 300 includes a first cutting groove 301 and a second cutting groove 302. As shown in FIG. 4, when the first cutting groove 301 and the second cutting groove 302 are formed on the back surface 7 side of all the division lines 6 of the wafer 1, the wafer processing method proceeds to the plasma etching step ST3. In the first embodiment, in the cutting step ST2, so-called step cutting is performed in which the wafer 1 is cut with the thick cutting blade 12-1 and then cut with the thin cutting blade 12-2. You may implement what is called a single cut cut with one cutting blade.

(Plasma etching step)
FIG. 5 is a cross-sectional view showing the configuration of an etching apparatus used in the plasma etching step of the wafer processing method shown in FIG. 6 is a cross-sectional view of the main part of the wafer after the plasma etching step of the wafer processing method shown in FIG.

  In the plasma etching step ST3, an etching gas obtained by converting the wafer 1 holding the adhesive tape 200 side by the chuck table 21 of the etching apparatus 20 shown in FIG. In this step, 2-1 (shown in FIG. 4) is removed by etching, and the substrate 2 is divided by the dividing groove 310 along the division line 6.

  In the plasma etching step ST3, the control unit 22 of the etching apparatus 20 operates the gate operation unit 23 to move the gate 24 downward in FIG. 5 and opens the opening 26 of the housing 25. Next, the wafer 1 on which the cutting step ST <b> 2 has been performed by unillustrated unloading / unloading means is transferred to the sealed space 27 in the housing 25 through the opening 26, and the chuck table 21 ( The functional layer 4 side of the wafer 1 is placed on an electrostatic chuck (ESC) via an adhesive tape 200. At this time, the control unit 22 operates the elevating drive unit 30 to raise the upper electrode 31. The control unit 22 applies power to the electrodes 32 and 33 provided in the workpiece holding unit 29 and holds the wafer 1 on the chuck table 21 by suction.

  The control unit 22 operates the gate operation unit 23 to move the gate 24 upward, and closes the opening 26 of the housing 25. The control unit 22 operates the elevating drive unit 30 to lower the upper electrode 31, so that the lower surface of the gas ejection part 34 constituting the upper electrode 31 and the wafer 1 held on the chuck table 21 constituting the lower electrode 28 are connected. The distance between them is set at a predetermined inter-electrode distance suitable for the plasma etching process.

  The control unit 22 operates the gas discharge unit 35 to evacuate the sealed space 27 in the housing 25 to maintain the pressure in the sealed space 27 at a predetermined pressure, and operates the refrigerant supply unit 36 to operate the lower electrode. Helium gas, which is a refrigerant, is circulated through the refrigerant introduction passage 37, the cooling passage 38, and the refrigerant discharge passage 39 provided in the inner wall 28 to suppress abnormal temperature rise of the lower electrode 28.

Next, the control unit 22 supplies SF ₆ gas that has been converted into plasma to the wafer 1 to etch the entire back surface 7 of the wafer 1 and advance the cutting groove 300 toward the front surface 3 of the substrate 2. Then, following the etching step, a plasma deposition step is performed in which plasmaized C ₄ F ₈ gas is supplied to the wafer 1 to deposit a coating on the back surface 7 of the wafer 1, the inner surfaces of the cutting grooves 301 and 302, and the bottom 304 of the cutting groove 300. Repeat alternately. In the etching step after the coating deposition step, the coating on the bottom 304 of the cutting groove 300 is removed and the bottom 304 of the cutting groove 300 is etched. Thus, in the plasma etching step ST3, the wafer 1 is plasma etched by a so-called Bosch method.

In the etching step, the control unit 22 operates the SF ₆ gas supply unit 40 to hold SF ₆ gas, which is an etching gas, on the chuck table 21 of the lower electrode 28 from the plurality of jet nozzles 41 of the upper electrode 31. It ejects toward the wafer 1. Then, the control unit 22 applies high-frequency power for generating and maintaining plasma from the high-frequency power source 42 to the upper electrode 31 while supplying SF ₆ gas for generating plasma, and draws ions from the high-frequency power source 42 to the lower electrode 28. High frequency power is applied. As a result, an isotropic plasma-ized etching gas composed of SF ₆ gas is generated in the space between the lower electrode 28 and the upper electrode 31, and this plasma-ized etching gas is drawn into the wafer 1, 1, the inner surface of the cutting grooves 301 and 302, and the bottom 304 of the cutting groove 300 are etched, and the cutting groove 300 is advanced toward the front surface 3 of the substrate 2.

Further, the coating deposition step, the control unit _22, a chuck table 21 of the _C 4 _{F 8} C 4 _{F 8} gas the lower electrode 28 from a plurality of ejection ports 41 of the upper electrode 31 is a working etching gas of the gas supply unit 43 It spouts toward the wafer 1 held above. The control unit 22 applies high-frequency power for generating and maintaining plasma from the high-frequency power source 42 to the upper electrode 31 in a state where C ₄ F ₈ gas for plasma generation is supplied, and ions from the high-frequency power source 42 to the lower electrode 28. Apply high frequency power to pull in. As a result, plasmaized etching gas composed of C ₄ F ₈ gas is generated in the space between the lower electrode 28 and the upper electrode 31, and this plasmaized etching gas is drawn into the wafer 1 to form a coating on the wafer 1. To deposit.

  In the plasma etching step ST3, the control unit 22 presets the number of times to repeat the etching step and the film deposition step according to the depth of the cutting groove 300, that is, the thickness of the wafer 1. In the plasma etching step ST3, the entire back surface 7 is etched by the first etching step as shown in FIG. It is thinned. In addition, as shown in FIG. 6, in the wafer 1 in which the etching step and the film deposition step are repeated a predetermined number of times, the remaining portion 2-1 of the bottom 304 of the cutting groove 300 is etched and removed in the etching step, The second cutting groove 302 reaches the functional layer 4, and the cutting groove 300 becomes a divided groove 310 that divides the substrate 2. In the wafer 1, the substrate 2 is divided by the dividing groove 310, the functional layer 4 is exposed in the dividing groove 310, and the functional layer 4 remains at the bottom of the dividing groove 310. When the plasma etching step ST3 is completed, the wafer processing method proceeds to the functional layer cutting step ST4.

(Functional layer cutting step)
FIG. 7 is a cross-sectional view showing a functional layer cutting step of the wafer processing method shown in FIG. FIG. 8 is a cross-sectional view of the main part of the wafer after the functional layer cutting step of the wafer processing method shown in FIG.

  In the functional layer cutting step ST4, after the substrate 2 is divided in the plasma etching step ST3, the laser beam 51 having a wavelength with which the laser processing apparatus 50 shown in FIG. In this step, the condensing point 51-1 is positioned on the functional layer 4 at the bottom of the dividing groove 310 and irradiated, and the functional layer 4 is cut along the dividing groove 310.

  In the functional layer cutting step ST4, the laser processing apparatus 50 holds the functional layer 4 side of the wafer 1 on the chuck table via the adhesive tape 200, and divides the laser beam irradiation unit 52 and the chuck table as shown in FIG. A condensing point 51-1 of a laser beam 51 having a wavelength (for example, 355 nm) having an absorptivity with respect to the functional layer 4 from the laser beam irradiation unit 52 while moving relatively along the planned line 6 is formed at the bottom of the dividing groove 310. The exposed functional layer 4 is set, and the functional layer 4 is irradiated with the laser beam 51. In the functional layer cutting step ST4, the functional layer 4 exposed at the bottom of the dividing groove 310 is ablated in each division planned line 6, and the functional layer 4 exposed at the bottom of the dividing groove 310 is cut, so that the wafer 1 Are divided into individual devices 5. Note that, in the functional layer cutting step ST4, the metal film and the TEG formed on the planned division line 6 (not shown) are also divided. In the first embodiment, the wafer 1 from which the functional layer 4 has been cut has debris generated by ablation processing attached to the inner surface of the dividing groove 310. As shown in FIG. 8, the wafer processing method proceeds to the cleaning step ST5 when the functional layer 4 exposed at the bottom of the dividing groove 310 is divided in all the dividing lines 6.

(Washing step)
FIG. 9 is a sectional side view showing a cleaning step of the wafer processing method shown in FIG. The cleaning step ST5 is a step of supplying cleaning water 57, which is water, to the wafer 1 after the functional layer cutting step ST4, and removing debris generated by irradiation with the laser beam 51 and adhering to the inner surface of the dividing groove 310.

  In the cleaning step ST5, as shown in FIG. 10, the cleaning device 53 sucks and holds the functional layer 4 side of the wafer 1 through the adhesive tape 200 on the holding surface 55 of the spinner table 54, and the spinner table 54 is rotated around the axis. While rotating, the cleaning water nozzle 56 is sprayed toward the back surface 7 of the wafer 1 while moving the cleaning water nozzle 56 in the radial direction on the wafer 1. In the cleaning step ST5, the cleaning water 57 flows on the back surface 7 of the wafer 1 and the inner surface of the dividing groove 310 to wash away the debris attached to these. In the cleaning step ST5, when the cleaning device 53 supplies the cleaning water 57 to the back surface 7 of the wafer 1 for a predetermined time while rotating the spinner table 54, the cleaning of the wafer 1 is finished and the wafer 1 is dried. In the wafer processing method, when the drying of the back surface 7 of the wafer 1 is finished, the process proceeds to the finish grinding step ST6.

(Finishing grinding step)
FIG. 10 is a side sectional view showing a finish grinding step of the wafer processing method shown in FIG. The finish grinding step ST6 is a step of grinding the back surface 7 of the wafer 1 to a finished thickness of 100 after the plasma etching step ST3, the functional layer cutting step ST4 and the cleaning step ST5.

  In the finish grinding step ST <b> 6, the grinding device 60 sucks and holds the functional layer 4 side of the wafer 1 through the adhesive tape 200 on the holding surface 62 of the chuck table 61. In the finish grinding step ST6, as shown in FIG. 10, the grinding water is supplied while the grinding wheel 64 for finish grinding is rotated by the spindle 63 and the chuck table 61 is rotated about the axis, and the grinding wheel 65 for finish grinding is provided. Is brought close to the chuck table 61 at a predetermined feed speed, and the back grinding 7 of the wafer 1, that is, the device 5, is finish ground with the finishing grinding wheel 65. In the finish grinding step ST6, the wafer 1, that is, the device 5 is ground until the finished thickness becomes 100. In the finish grinding step ST6, when the wafer 1, that is, the device 5 is ground until the finished thickness is 100, the first cutting groove 301 is removed and the step between the first cutting groove 301 and the second cutting groove 302 is removed. Is done. In the wafer processing method, when the wafer 1, that is, the device 5 is thinned to a finished thickness 100, the process proceeds to the reattachment step ST 7.

(Replacement step)
FIG. 11 is a cross-sectional view of a wafer showing a re-attaching step of the wafer processing method shown in FIG. In the replacement step ST7, after performing the plasma etching step ST3, the functional layer cutting step ST4, the cleaning step ST5, and the finish grinding step ST6, the die attach film 202 is attached to the back surface 7 of the wafer 1 and the expanded tape 203 is attached. Then, the adhesive tape 200 is peeled off.

  In the attaching step ST7, a die attach film 202 for adhering the device 5 is attached to the back surface 7 of the wafer 1 that is finish-ground in the finish grinding step ST6, that is, the device 5. In the attaching step ST7, as shown in FIG. 11, the die attach film 202 laminated on the expanded tape 203 having the annular frame 204 attached to the outer peripheral edge is attached to the back surface 7 of the wafer 1, and the functional layer 4 The adhesive tape 200 is peeled off. The expandability of the expanded tape 203 is greater than the stretchability of the die attach film 202. When the adhesive tape 200 is peeled off from the functional layer 4, the wafer processing method proceeds to the die attach film breaking step ST8.

(Die attach film breaking step)
FIG. 12 is a cross-sectional view showing a state in which the wafer is held in the expansion device in the die attach film breaking step of the wafer processing method shown in FIG. FIG. 13 is a cross-sectional view showing a state in which the die attach film is broken for each device in the die attach film breaking step of the wafer processing method shown in FIG.

  In the die attach film breaking step ST8, after the reattaching step ST7 is performed, the die attach film 202 is cooled to reduce stretchability, and then the expanded tape 203 is stretched to expand the die attach film 202. It is a step which fractures along. In the first embodiment, in the die attach film breaking step ST8, as shown in FIG. 12, with the functional layer 4 side facing upward, the expansion device 70 sandwiches the annular frame 204 with the clamp portion 71 and replaces it. The wafer 1 after step ST7 is fixed. At this time, as shown in FIG. 12, the expansion device 70 keeps the cylindrical expansion drum 72 in contact with the region between the wafer 1 and the annular frame 204 of the expanded tape 203. The expansion drum 72 has an inner diameter and an outer diameter that are smaller than the inner diameter of the annular frame 204 and larger than the outer diameter of the wafer 1, and is disposed at a position that is coaxial with the annular frame 204 fixed by the clamp portion 71.

  In the first embodiment, in the die attach film breaking step ST8, the expansion device 70 operates the cooling device 73, cools the die attach film 202, and reduces the stretchability of the die attach film 202. In the first embodiment, as shown in FIG. 12, the cooling device 73 sprays cool air 74 having a temperature lower than normal temperature onto the expanded tape 203 from the back surface 7 side, and cools the die attach film 202 via the expanded tape 203. However, the present invention is not limited to the configuration shown in FIG.

  In the first embodiment, in the die attach film breaking step ST8, after the cooling device 73 cools the die attach film 202 for a predetermined time, the expansion device 70 lowers the clamp portion 71 as shown in FIG. Then, since the expand tape 203 is in contact with the expansion drum 72, the expand tape 203 is expanded in the surface direction. In the die attach film breaking step ST8, as a result of expansion, a radial tensile force acts on the expanded tape 203. When a tensile force acts radially on the expanded tape 203 adhered to the back surface 7 of the wafer 1 via the die attach film 202 in this way, the wafer 1 is divided into individual devices 5 in the functional layer cutting step ST4. Therefore, the tensile force is concentrated on the portion of the die attach film 202 located between the devices 5. And as shown in FIG. 13, the die-attach film 202 in which the expandability is lowered by cooling is divided into devices 5 by breaking the portion located between the devices 5. In Embodiment 1, the wafer processing method breaks the die attach film 202 using a so-called cool expanding technique in the die attach film breaking step ST8.

  In the first embodiment, in the die attach film breaking step ST8, the clamp portion 71 is lowered and the expanded tape 203 is expanded. However, the present invention is not limited to this, and the expansion drum 72 may be raised. In short, the extension drum 72 may be raised relative to the clamp portion 71 and the clamp portion 71 may be lowered relative to the extension drum 72. The wafer processing method ends when the die attach film 202 is divided for each device 5. After that, the device 5 is picked up from the expanded tape 203 by the pickup (not shown) for each die attach film 202.

  In the wafer processing method according to the first embodiment, the cutting groove 300 is formed along the planned dividing line 6 from the back surface 7 in the cutting step ST2, and then plasma etching is performed from the back surface 7 side in the plasma etching step ST3. Since the wafer 1 is divided by advancing 300 toward the surface 3 of the substrate 2, plasma dicing without a mask can be realized. For this reason, since the wafer processing method is smaller than the device divided by cutting, an expensive mask is not required in the wafer 1 processing method including the device 5 suitable for dividing by plasma etching. . As a result, the wafer processing method can divide the wafer 1 into individual devices 5 by performing plasma etching on the wafer 1 while suppressing the cost.

  The wafer processing method is a so-called cool expanding technique in which the die attach film 202 is attached to the back surface 7 of the wafer 1 in the reattaching step ST7, and then the die attach film 202 is cooled and broken in the die attach film breaking step ST8. Is used. As a result, the wafer processing method does not require laser ablation when dividing the die attach film 202 for each device 5, so that alignment for irradiating a laser beam is not required, and the wafer is efficiently processed. There is also an effect that the device 5 with the touch film 202 can be formed.

  In the functional layer cutting step ST4, the wafer processing method cuts the functional layer 4 exposed at the bottom of the dividing groove 310 by ablation processing using the laser beam 51. Therefore, after the plasma etching step ST3, the dividing line 6 Even if the substrate 2 located at is left, the wafer 1 can be divided into individual devices 5 after the functional layer cutting step ST4. In the functional layer cutting step ST4, the laser beam 51 is irradiated from the back surface 7 side, and the cleaning step ST5 is performed after the functional layer cutting step ST4. There is also an effect that it does not remain on the surface 3, that is, the device 5.

  In the wafer processing method, the adhesive tape 200 is attached to the functional layer 4 side in the protective member disposing step ST1 before the cutting step ST2 and the finish grinding step ST6. For this reason, it can suppress that the contamination which arises at the time of cutting step ST2 and finish grinding step ST6 adheres to the device 5. FIG.

  In the functional layer cutting step ST4, the wafer processing method divides the functional layer 4 remaining on the bottom of the cutting groove 300 by irradiating the laser beam 51, so that the functional layer 4 such as a low-k film is laminated. The wafer 1 can be divided into individual devices 5. Further, in the wafer processing method, the adhesive tape 200 is attached to the functional layer 4 side in the protective member disposing step ST1 before the functional layer cutting step ST4, and the laser beam 51 is applied from the back surface 7 side in the functional layer cutting step ST4. Since the functional layer 4 at the groove bottom of the cutting groove 300 is irradiated, debris generated during ablation processing can be prevented from adhering to the device 5.

Further, in the wafer processing method, in the cutting step ST2, after forming the first cutting groove 301, the second cutting groove 302 narrower than the first cutting groove 301 is formed on the groove bottom 303 of the first cutting groove 301, and In the plasma etching step ST3, the wafer 1 is plasma etched by the Bosch method. For this reason, in the wafer processing method, plasma made of SF ₆ gas can be drawn into the wafer 1 through the bottom 304 of the cutting groove 300 in the etching step of the plasma etching step ST3. As a result, the wafer processing method can efficiently divide the substrate 2 of the wafer 1.

  Further, in the wafer processing method, in the cutting step ST2, by forming the cutting groove 300 deeper than the finished thickness 100 of the wafer 1, a step having a finished thickness of 100 or more is provided on the back surface 7 side, and after the plasma etching step ST3. While the thickness of the remaining wafer 1 becomes the finished thickness, the cutting groove 300 having a desired depth can be formed.

  Further, the wafer processing method is a surface in which the side surfaces of the individually divided devices 5 are removed by plasma etching in order to divide the substrate 2 along the planned dividing line 6 in the plasma etching step ST3. For this reason, the wafer processing method also has an effect that a chip 5 having high bending strength can be manufactured without chipping due to cutting remaining on the side surfaces of the device 5 divided individually.

  Further, in the processing method of the wafer, in the finish grinding step ST6, the back surface 7 of the wafer 1 is ground to remove the step between the first cutting groove 301 and the second cutting groove 302. Therefore, the device 5 having a predetermined dimension is used. Can be obtained.

  In addition, since the wafer processing method includes the reattachment step ST7 and the die attach film breaking step ST8, the device 5 that can be fixed to a substrate or the like can be obtained.

[Embodiment 2]
A wafer processing method according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 14 is a flowchart showing a flow of a wafer processing method according to the second embodiment. FIG. 15 is a sectional side view showing a preliminary grinding step of the wafer processing method shown in FIG. FIG. 16 is a cross-sectional view of the main part of the wafer after the preliminary grinding step of the wafer processing method shown in FIG. In FIG. 14, FIG. 15, and FIG. 16, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The wafer processing method according to the second embodiment is the same as that of the first embodiment except that a pre-grinding step ST10 is provided as shown in FIG. The preliminary grinding step ST10 is a step for grinding the back surface 7 of the wafer 1 in advance before the plasma etching step ST3. In the second embodiment, in the wafer processing method, the preliminary grinding step ST10 is performed after the protective member disposing step ST1 and before the cutting step ST2, but in the present invention, before the plasma etching step ST3, You may implement before protection member arrangement | positioning step ST1, or after cutting step ST2.

  In preliminary grinding step ST10, the grinding device 80 sucks and holds the functional layer 4 side of the wafer 1 on the holding surface 82 of the chuck table 81 via the adhesive tape 200. In the preliminary grinding step ST10, as shown in FIG. 15, the grinding water is supplied while the grinding wheel 84 for rough grinding is rotated by the spindle 83 and the chuck table 81 is rotated around the axis, and the grinding wheel 85 for rough grinding is provided. Is brought close to the chuck table 81 at a predetermined feed rate, and the back surface 7 of the wafer 1 is roughly ground by the rough grinding wheel 85. The rough grinding wheel 85 is a grinding wheel having larger abrasive grains than the finish grinding wheel 65.

  In the preliminary grinding step ST10, as shown in FIG. 16, the wafer 1 is ground until the finished thickness 100 and the thickness 101 removed in the plasma etching step ST3 are equal to or greater than the total thickness. In the second embodiment, the wafer processing method proceeds to the plasma etching step ST3 when the wafer 1 is ground until the finished thickness 100 and the thickness 101 removed in the plasma etching step ST3 are equal to or greater than the thickness. In the present invention, in the preliminary grinding step ST10, it is desirable to thin the wafer 1 to a thickness that is substantially equal to the combined thickness of the finished thickness 100 and the thickness 101 removed in the plasma etching step ST3.

  In the wafer processing method according to the second embodiment, since the cutting groove 300 is formed along the planned dividing line 6 from the back surface 7 in the cutting step ST2, plasma etching is performed from the back surface 7 side in the plasma etching step ST3. The plasma dicing can be realized. As a result, as in the first embodiment, the wafer processing method can divide the wafer 1 into individual devices 5 by performing plasma etching on the wafer 1 while reducing costs.

  Further, in the wafer processing method according to the second embodiment, since the wafer 1 is thinned by performing the preliminary grinding step ST10 before the plasma etching step ST3, the removal amount of the substrate 2 of the wafer 1 at the time of the plasma etching step ST3. Can be suppressed. As a result, the wafer processing method according to the second embodiment can suppress the amount of so-called outgas generated in the plasma etching step ST3.

  In the wafer processing method according to the second embodiment, the pre-grinding step ST10 is performed before the cutting step ST2, and the back surface 7 of the wafer 1 is ground. Even on a textured surface (a surface having fine irregularities), the back surface 7 can be flattened before the cutting step ST2. As a result, in the wafer processing method according to the second embodiment, in the cutting step ST2, the cutting blades 12-1 and 12-2 and the scheduled dividing line 6 when the alignment is performed based on the image captured by the infrared camera are performed. Misalignment can be suppressed.

[Embodiment 3]
A wafer processing method according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 17 is a cross-sectional view of the main part of the wafer after the plasma etching step of the wafer processing method according to the third embodiment. In FIG. 17, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The wafer processing method according to the third embodiment is the same as that of the first embodiment except that, in the plasma etching step ST3, the wafer 1 is etched by anisotropic etching instead of the Bosch method. In the wafer processing method according to the third embodiment, in the plasma etching step ST3, the shape of the back surface 7 and the cutting groove 300 of the wafer 1 before etching shown by the dotted line in FIG. 17 is maintained, and as shown by the solid line in FIG. Then, the entire substrate 2 is etched from the back surface 7 side, and the substrate 2 is divided along the planned dividing line 6.

  In the wafer processing method according to the third embodiment, since the cutting groove 300 is formed along the planned dividing line 6 from the back surface 7 in the cutting step ST2, plasma etching is performed from the back surface 7 side in the plasma etching step ST3. The plasma dicing can be realized. As a result, as in the first embodiment, the wafer processing method can divide the wafer 1 into individual devices 5 by performing plasma etching on the wafer 1 while reducing costs.

  Further, in the wafer processing method according to the third embodiment, since the substrate 2 of the wafer 1 is etched from the back surface 7 side by anisotropic etching in the plasma etching step ST3, the substrate of the wafer 1 is more than the case of etching by the Bosch method. 2 can be thinned. As a result, the processing method of the wafer 1 can suppress the grinding amount of the substrate 2 in the finish grinding step ST6.

  In the wafer processing method according to the third embodiment, the pre-grinding step ST10 may be performed as in the second embodiment.

[Embodiment 4]
A wafer processing method according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 18 is a cross-sectional view showing a configuration of an etching apparatus used in the plasma etching step of the wafer processing method according to the fourth embodiment. In FIG. 18, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The wafer processing method according to the fourth embodiment is the same as that of the first embodiment except that the configuration of the etching apparatus 20-4 shown in FIG. 18 used in the plasma etching step ST3 is different from that of the etching apparatus 20.

The etching apparatus 20-4 does not apply high-frequency power to the electrodes 28 and 31 to plasma the etching gas in the sealed space 27, but introduces plasmaized etching gas or the like into the sealed space 27 in the housing 25. This is a remote plasma type plasma etching apparatus. In the etching apparatus 20-4, as shown in FIG. 18, a pipe 45 to which an inert gas is supplied from an inert gas supply unit (not shown) penetrates and is connected to the outer wall of the housing 25. The inert gas supplied by the inert gas supply unit is a rare gas such as argon gas (Ar) or helium gas (He), nitrogen gas (N ₂ ), hydrogen gas (H ₂ ), or the like. It can be composed of a mixed gas or the like in which is mixed.

  Further, as shown in FIG. 18, the etching apparatus 20-4 has a supply pipe 46 to which etching gas from the gas supply units 40 and 43 is supplied penetratingly connected to the upper wall of the housing 25. The supply pipe 46 is provided with an electrode 47 for applying high-frequency power to the etching gas flowing through. The supply pipe 46 introduces the etching gas supplied from the gas supply units 40 and 43 into the sealed space 27 in the housing 25. The electrode 47 receives the high frequency power from the high frequency power source 42 and turns the gas flowing in the supply pipe 46 into plasma. In addition, the etching apparatus 20-4 includes a dispersion member 48 that disperses the plasmaized etching gas supplied from the supply pipe 46 to the sealed space 27.

  In the wafer processing method according to the fourth embodiment, after the control unit 22 of the etching apparatus 20-4 accommodates the wafer 1 in the sealed space 27 in the housing 25 in the plasma etching step ST3, as in the first embodiment, It is sucked and held on the chuck table 21. In the plasma etching step ST3 of the wafer processing method according to the fourth embodiment, the control unit 22 operates the gas discharge unit 35 to evacuate the sealed space 27 and operates the inert gas supply unit to operate the sealed space 27. An inert gas is supplied to maintain the pressure in the sealed space 27 at a predetermined pressure, and the refrigerant supply unit 36 is operated to circulate helium gas to suppress abnormal temperature rise of the lower electrode 28.

In the wafer processing method according to the fourth embodiment, plasma etching is performed on the wafer 1 by the Bosch method in the plasma etching step ST3 as in the first embodiment. In the etching step of the plasma etching step ST3, the control unit 22 operates the SF ₆ gas supply unit 40 and applies high frequency power for generating and maintaining plasma from the high frequency power source 42 to the electrode 47, thereby converting the SF ₆ gas into plasma. Then, it is ejected from the supply pipe 46 toward the wafer 1 held on the chuck table 21 of the lower electrode 28. Then, the control unit 22 applies high frequency power for drawing ions from the high frequency power source 42 to the lower electrode 28 to etch the back surface 7 of the wafer 1, the inner surfaces of the cutting grooves 301 and 302, and the bottom 304 of the cutting groove 300. .

In the film deposition step of the plasma etching step ST3, the control unit 22 operates the C ₄ F ₈ gas supply unit 43 to convert the C ₄ F ₈ gas into plasma with high frequency power applied from the high frequency power source 42 to the electrode 47, It is ejected from the supply pipe 46 toward the wafer 1 held on the chuck table 21 of the lower electrode 28. Then, the control unit 22 applies high frequency power for drawing ions from the high frequency power source 42 to the lower electrode 28 to deposit a film on the wafer 1.

  In the wafer processing method according to the fourth embodiment, since the cutting groove 300 is formed along the planned dividing line 6 from the back surface 7 in the cutting step ST2, plasma etching is performed from the back surface 7 side in the plasma etching step ST3. The plasma dicing can be realized. As a result, as in the first embodiment, the wafer processing method can divide the wafer 1 into individual devices 5 by performing plasma etching on the wafer 1 while reducing costs.

  In addition, since the wafer processing method according to the fourth embodiment uses the remote plasma etching apparatus 20-4 in the plasma etching step ST3, the etching apparatus 20-4 supplies ions mixed into the plasmaized etching gas. Since it can be prevented from colliding with the inner surface of 46 and reaching the sealed space 27 in the housing 25, the substrate 2 can be divided for each device 5 even with the narrower cutting groove 300.

  In the wafer processing method according to the fourth embodiment, the preliminary grinding step ST10 may be performed as in the second embodiment.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention. For example, in the present invention, the functional layer 4, the metal film, and the TEG formed on the scheduled division line 6 may be removed by ablation by irradiating the surface with a laser beam before the cutting step ST <b> 2. In the present invention, in the plasma etching step ST3, oxygen gas may be mixed in the plasma etching gas in order to etch the functional layer 4 made of resin. In this case, the functional layer 4 remaining on the bottom 304 of the cutting groove 300 can be removed without performing the functional layer cutting step ST4. Alternatively, in the present invention, the functional layer 4 is partially removed by oxygen gas, and is partially removed by applying an external force that expands in the radial direction (specifically, by expanding the adhesive tape 200). You may divide | segment the functional layer 4 by tearing a part from a fracture | rupture starting point. In the present invention, when an oxide film is previously formed on the back surface 7 of the wafer 1, plasma etching may be performed using the oxide film as a mask in the plasma etching step ST3. In the present invention, the back surface 7 of the wafer 1 is roughly ground using the rough grinding wheel 85 in both the finish grinding step ST6 and the preliminary grinding step ST10, and then the back surface 7 of the wafer 1 is ground using the finish grinding wheel 65. The finish grinding may be performed, the back surface 7 of the wafer 1 may be only ground, or the back surface 7 of the wafer 1 may be only finish ground.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Substrate 2-1 Remaining part 3 Front surface 4 Functional layer 5 Device 6 Dividing line 7 Back surface 12, 12-1, 12-2 Cutting blade 21 Chuck table 51 Laser beam 51-1 Condensing point 100 Finish thickness 200 Adhesion Tape (protective member)
202 Die attach film 203 Expanding tape 300 Cutting groove 304 Bottom 310 Dividing groove ST1 Protective member placement step ST2 Cutting step ST3 Plasma etching step ST4 Functional layer cutting step ST6 Finish grinding step ST7 Replacement step ST8 Die attach film breaking step ST10 Pre-grinding Step

Claims (4)

A wafer processing method for dividing a wafer having a plurality of devices formed on a surface along a predetermined dividing line dividing the plurality of devices,
A protective member disposing step of disposing a protective member on the surface side of the wafer;
A cutting step of cutting a cutting blade on the back surface side of the wafer and forming a cutting groove having a depth not reaching the surface of the wafer along the planned dividing line;
A gas that is plasmatized on the back side of the wafer holding the protective member side by a chuck table is supplied, and the remaining portion of the bottom of the cutting groove is removed by etching. A plasma etching step to divide the wafer;
After performing the plasma etching step, attaching a die attach film to the back surface of the wafer and attaching an expand tape, a re-attaching step of peeling the protective member from the front surface of the wafer;
A die attach film breaking step in which, after performing the reattachment step, the die attach film is cooled to reduce stretchability, and then the expanded tape is expanded to break the die attach film along individual devices; A wafer processing method comprising:   The wafer includes a substrate and a functional layer that is laminated on the surface of the substrate to form a device. After the substrate is divided in the plasma etching step, a condensing point of a laser beam is formed from the back side of the wafer. The wafer processing method according to claim 1, further comprising a functional layer cutting step of irradiating and cutting the functional layer positioned at the bottom of the dividing groove.   The wafer processing method according to claim 1, further comprising a finish grinding step of grinding the back surface of the wafer to a finished thickness after the plasma etching step.   The wafer processing method according to claim 1, further comprising a preliminary grinding step of pre-grinding the back surface of the wafer before the plasma etching step.

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