JP2019212772A - Wafer processing method - Google Patents

Abstract

To provide a wafer processing method capable of performing plasma etching while holding down costs.SOLUTION: A wafer processing method for dividing a wafer in which a functional layer is laminated on a surface of a substrate comprises a protection member arranging step (ST1), a cutting step (ST2), a plasma etching step (ST3), a functional layer etching step (ST4), and a fracturing step (ST5). The protection member arranging step arranges an adhesive tape on a functional layer side. The cutting step forms a cut groove with a depth not reaching the functional layer on a rear surface of the wafer along division schedule lines. The plasma etching step plasma-etches the rear surface side of the wafer holding the adhesive tape side by a chuck table, and divides the substrate at a division groove along division schedule lines. The functional layer etching step removes at least a part of the functional layer exposed at a bottom of the division groove. The fracturing step stretches the adhesive tape and fractures the functional layer along the division schedule lines.SELECTED DRAWING: 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 includes a wafer in which a plurality of devices are formed by laminating a functional layer containing a resin on a surface of a substrate. A method for processing a wafer to be divided along a division line to be divided, comprising: a protective member disposing step of disposing a protective member on the functional layer side of the front surface of the wafer; and cutting a cutting blade on the back surface of the wafer. A cutting step for forming a cutting groove having a depth that does not reach the functional layer on the substrate along the division line, and the wafer holding the protective member side with a chuck table is converted into a plasma on the back surface side. A plasma etching step of supplying a gas, etching and removing the substrate remaining at the bottom of the cutting groove, and dividing the substrate by dividing grooves along the planned dividing line; A functional layer etching step of supplying a gas containing ozone to the back surface side of the wafer after performing the chucking step and removing at least a part of the functional layer including the resin exposed at the bottom of the dividing groove; After the etching step, the protective member is stretched and expanded, and a breaking step is provided in which the functional layer is broken along the planned dividing line using the removed portion as a break starting point.

  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 a configuration of an etching apparatus used in the plasma etching step and the functional layer 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 of the main part of the wafer after the functional layer etching step of the wafer processing method shown in FIG. FIG. 8 is a cross-sectional view showing a state where the wafer is held by the expansion device in the breaking step of the wafer processing method shown in FIG. FIG. 9 is a cross-sectional view showing a state in which the functional layer is broken along the planned dividing line in the breaking 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 the wafer after the die attach film attaching step of the wafer processing method shown in FIG. 12 is a cross-sectional view showing a die attach film dividing step of the wafer processing method shown in FIG. FIG. 13 is a cross-sectional view of the main part of the wafer after the die attach film dividing 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 and the functional layer 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 in 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 having silicon, sapphire, gallium arsenide, or the like as the substrate 2. As shown in FIG. 1, the wafer 1 has a plurality of devices 5 formed by laminating a functional layer 4 containing a resin on a surface 3 of a 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.

  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 etching step ST4, a breaking step ST5, a finish grinding step ST6, A die attach film attaching step ST7 and a die attach film dividing step ST8 are provided.

(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. 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 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.

  In the cutting step ST 2, the cutting blade 12 of the cutting apparatus 10 shown in FIG. 3 is cut into the back surface 7 of the substrate 2 of the wafer 1, and a cutting groove 300 having a depth that does not reach the functional layer 4 is formed along the planned dividing line 6. This is a step of forming on the substrate 2. 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 <b> 2, the first cutting groove 301 and the second cutting groove 302 are formed, and the cutting groove 300 has a depth exceeding the finished thickness 100 of the wafer 1 and not reaching the functional layer 4 on the back surface 7 of the wafer 1. To promote the penetration of the plasma-ized etching gas into the cutting groove 300 in the plasma etching step ST3. 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 a configuration of an etching apparatus used in the plasma etching step and the functional layer 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 held on the adhesive tape 200 side by the chuck table 21 of the etching apparatus 20 shown in FIG. 5 into plasma on the back surface 7 side is supplied, and the bottom 304 of the cutting groove 300 (FIG. 4). The substrate 2 remaining in (1) is removed by etching, and the substrate 2 is divided by the dividing grooves 310 along the division lines 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, in the film deposition step, the control unit 22 operates the C ₄ F ₈ gas supply unit 43 to cause C ₄ F ₈ gas as an etching gas to flow from the plurality of jet nozzles 41 of the upper electrode 31 to the chuck table 21 of the lower electrode 28. 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 generating plasma 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 number of times the control unit 22 repeats the etching step and the film deposition step is preset 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. Further, 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 substrate 2 remaining on the bottom 304 of the cutting groove 300 is etched and removed in the etching step, as shown in FIG. The groove 300 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 etching step ST4.

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

  In the functional layer etching step ST4, after performing the plasma etching step ST3, a gas containing ozone is supplied to the back surface 7 side of the wafer 1, and at least a part of the functional layer 4 containing the resin exposed at the bottom of the dividing groove 310 is removed. Step to remove.

  In the functional layer etching step ST4, the control unit 22 of the etching apparatus 20 sucks and holds the wafer 1 on the chuck table 21, maintains the pressure of the sealed space 27 at a predetermined pressure, and abnormally raises the temperature of the lower electrode 28. In a state in which the gas supply unit 44 is suppressed, the gas supply unit 44 is operated to eject a gas containing ozone from the plurality of jet nozzles 41 of the upper electrode 31 toward the wafer 1 held on the chuck table 21 of the lower electrode 28. 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 a gas containing ozone, and the high-frequency power for drawing ions from the high-frequency power source 42 into the lower electrode 28. Apply power. Thereby, an isotropic plasma gas composed of a gas containing ozone is generated in the space between the lower electrode 28 and the upper electrode 31, and the plasma gas is drawn into the wafer 1 to deposit a film. Using the coating formed in the step as a mask, the portion 4-1 exposed at the bottom of the dividing groove 310 of the functional layer 4 is etched.

  In the functional layer etching step ST4, when the control unit 22 etches the portion 4-1 exposed at the bottom of the dividing groove 310 of the functional layer 4 for a predetermined time, the high frequency power from the high frequency power source 42 to the electrodes 28 and 31 is generated. The application and the operation of the gas supply unit 44 are stopped. In the functional layer etching step ST4, the portion 4-1 exposed at the bottom of the dividing groove 310 of the functional layer 4 etched for a predetermined time is more than the other portion on which the substrate 2 is laminated as shown in FIG. The etching groove 311 is formed by being thinned. When the functional layer etching step ST4 is completed, the wafer processing method proceeds to the breaking step ST5.

(Breaking step)
FIG. 8 is a cross-sectional view showing a state where the wafer is held by the expansion device in the breaking step of the wafer processing method shown in FIG. FIG. 9 is a cross-sectional view showing a state in which the functional layer is broken along the planned dividing line in the breaking step of the wafer processing method shown in FIG.

  In the breaking step ST5, after the functional layer etching step ST4, the adhesive tape 200 is stretched and expanded, and the portion 4-1 exposed and thinned at the bottom of the dividing groove 310 of the functional layer 4, which is the removed portion, is removed. This is a step of breaking the functional layer 4 along the planned dividing line 6 as a break starting point. In the first embodiment, in the breaking step ST5, as shown in FIG. 8, the expansion device 50 sandwiches the annular frame 201 with the clamp portion 51 with the back surface 7 facing upward, and after the functional layer etching step ST4. The wafer 1 is fixed. At this time, as shown in FIG. 8, the expansion device 50 keeps the cylindrical expansion drum 52 in contact with the region between the wafer 1 and the annular frame 201 of the adhesive tape 200. The expansion drum 52 has an inner diameter and an outer diameter that are smaller than the inner diameter of the annular frame 201 and larger than the outer diameter of the wafer 1, and is disposed at a position that is coaxial with the annular frame 201 fixed by the clamp portion 51.

  In the first embodiment, in the breaking step ST5, as shown in FIG. 9, the expansion device 50 lowers the clamp portion 51. Then, since the adhesive tape 200 is in contact with the expansion drum 52, the adhesive tape 200 is expanded in the surface direction. In the breaking step ST5, as a result of the expansion, a radial tensile force acts on the adhesive tape 200. When a radial force acts on the adhesive tape 200 adhered to the surface 3 of the wafer 1 in this way, the wafer 1 is exposed to the portion 4 exposed at the bottom of the dividing groove 310 of the functional layer 4 in the functional layer etching step ST4. Since -1 is thinned, as shown in FIG. 9, the functional layer 4 is divided for each device 5 with the above-described portion 4-1 as a starting point of breakage, and is divided into individual devices 5. In the first embodiment, in the breaking step ST5, the clamp portion 51 is lowered and the adhesive tape 200 is expanded. However, the present invention is not limited to this, and the expansion drum 52 may be raised. The extension drum 52 may be raised relative to the clamp part 51 and the clamp part 51 may be lowered relative to the extension drum 52. The wafer processing method proceeds to the finish grinding step ST6 after completing the breaking step ST5.

(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 etching step ST4 and the fracture 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 of 100, the process proceeds to the die attach film attaching step ST7.

(Die attach film sticking step)
FIG. 11 is a cross-sectional view of the wafer after the die attach film attaching step of the wafer processing method shown in FIG. The die attach film sticking step ST7 is a step for sticking the die attach film 202 to the back surface 7 of the wafer 1 after the plasma etching step ST3, the functional layer etching step ST4, the breaking step ST5, and the finish grinding step ST6.

  In the die attach film attaching step ST7, the die attach film 202 for adhering the device 5 is attached to the wafer 1 that has been finish-ground in the finish grinding step ST6, that is, the back surface 7 of the device 5. In the die attach film sticking step ST7, as shown in FIG. 11, the die attach film 202 laminated on the dicing tape 203 with the annular frame 204 stuck on the outer peripheral edge is stuck on the back surface 7 of the wafer 1, The adhesive tape 200 is peeled off from the functional layer 4. When the adhesive tape 200 is peeled off from the functional layer 4, the wafer processing method proceeds to the die attach film dividing step ST8.

(Die attach film dividing step)
12 is a cross-sectional view showing a die attach film dividing step of the wafer processing method shown in FIG. FIG. 13 is a cross-sectional view of the main part of the wafer after the die attach film dividing step of the wafer processing method shown in FIG. The die attach film dividing step ST8 is a step of dividing the die attach film 202 by irradiating the laser beam 71 to the die attach film 202 along the dividing groove 310 by the laser processing device 70 shown in FIG.

  In the die attach film dividing step ST8, the laser processing apparatus 70 holds the back surface 7 side of the wafer 1 via the dicing tape 203 on the chuck table, and divides the laser beam irradiation unit 72 and the chuck table as shown in FIG. A laser beam 71 having a wavelength (for example, 355 nm) having an absorptivity with respect to the die attach film 202 from the laser beam irradiation unit 72 while being relatively moved along the planned line 6 is applied to the die attach film 202 exposed in the dividing groove 310. Irradiate. In the die attach film dividing step ST8, the die attach film 202 exposed in the dividing groove 310 is subjected to ablation processing in each division planned line 6, and the die attach film 202 exposed in the dividing groove 310 is divided. As shown in FIG. 13, the wafer processing method ends when the die attach film 202 exposed in the dividing grooves 310 is divided in all the dividing lines 6. After that, the device 5 is picked up from the dicing tape 203 by a 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.

  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.

  Further, in the wafer processing method, the functional layer 4 exposed at the bottom of the dividing groove 310 is plasma-etched using a gas containing ozone in the functional layer etching step ST4, and the portion 4-1 of the functional layer 4 is removed in the breaking step ST5. Divide as the break starting point. For this reason, even if the functional layer 4 such as a low-k film remains after the plasma etching step ST3, the wafer processing method is slightly etched in the functional layer 4 by plasma etching using a gas containing ozone. And the etching groove 311 is broken at the break starting point. As a result, in the wafer processing method, it is not necessary to irradiate the functional layer 4 with a laser beam in order to divide the functional layer 4, so that it is not necessary to perform alignment for irradiating the laser beam, and the functional layer 4 is laminated. The processed wafer 1 can be efficiently divided into individual devices 5.

  Further, in the wafer processing method, in the breaking step ST5, the adhesive tape 200 is expanded by the expansion device 50 to divide the functional layer 4 for each device 5. Therefore, it is necessary to perform ablation processing to divide the functional layer 4. The 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 a 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 remaining wafer 1 has a finished thickness of 100, 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 die attach film sticking step ST7 and the die attach film dividing 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.

  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. Further, according to the present invention, in the preliminary grinding step ST10, after the rough grinding, the back surface 7 of the wafer 1 may be finish ground by the finishing grinding wheel 65 by the same method as the finishing grinding step ST6.

  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 to grind the back surface 7 of the wafer 1. Therefore, the back surface 7 of the wafer 1 is removed before the pre-grinding step ST10. 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 and the functional layer 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 and the functional layer etching step ST4 is different from that of the etching apparatus 20. It is.

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 comprised with the mixed gas etc. which mixed.

  In addition, as shown in FIG. 18, the etching apparatus 20-4 has a supply pipe 46 to which an etching gas or gas containing ozone from the gas supply units 40, 43, 44 is supplied penetrates the upper wall of the housing 25. The supply pipe 46 is provided with an electrode 47 for connecting and applying high-frequency power to the gas flowing in the supply pipe 46. The supply pipe 46 introduces the gas supplied from the gas supply units 40, 43, 44 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 plasmaized 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, and 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, in the functional layer etching step ST4, the control unit 22 sucks and holds the wafer 1 on the chuck table 21 and maintains the pressure of the sealed space 27 at a predetermined pressure. In a state in which the abnormal temperature rise of the electrode 28 is suppressed, the gas supply unit 44 is operated to convert the gas containing ozone into plasma with high frequency power applied from the high frequency power source 42 to the electrode 47, and the chuck table of the lower electrode 28 from the supply pipe 46. It spouts toward the wafer 1 held on 21. 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 portion 4-1 exposed at the bottom of the dividing groove 310 of the functional layer 4.

  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 and the functional layer etching step ST4, the etching apparatus 20-4 is mixed with plasma gas. Can be prevented from colliding with the inner surface of the supply pipe 46 and reaching the sealed space 27 in the housing 25, so that the substrate 2 can be divided for each device 5 even with the narrower cutting groove 300. it can.

  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.

  Further, according to the present invention, in the breaking step ST5, the expansion device 50 is accommodated in a cooling chamber whose interior is cooled, cold air is blown to the adhesive tape 200, or the adhesive tape 200 is cooled to a cooling table whose holding surface is cooled. After holding and cooling the functional layer 4 to reduce the stretchability of the functional layer 4, the functional layer 4 may be divided for each device 5 using the portion 4-1 as a starting point of breakage. 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.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Substrate 3 Front surface 4 Functional layer 4-1 Part 5 Device 6 Line to be divided 7 Back surface 12, 12-1, 12-2 Cutting blade 21 Chuck table 100 Finished thickness 200 Adhesive tape (protective member)
300 Cutting groove 304 Bottom 310 Dividing groove ST1 Protection member disposing step ST2 Cutting step ST3 Plasma etching step ST4 Functional layer etching step ST5 Breaking step ST6 Finish grinding step ST10 Pre-grinding step

Claims (3)

A wafer processing method for dividing a wafer in which a plurality of devices are formed by laminating a functional layer containing a resin on a surface of a substrate, along a division schedule line dividing the plurality of devices,
A protective member disposing step of disposing a protective member on the functional layer side of the surface of the wafer;
A cutting step in which a cutting blade is cut on the back surface of the wafer, and a cutting groove having a depth not reaching the functional layer is formed on the substrate along the division line;
A gas that is plasmatized to the back side of the wafer holding the protective member side with a chuck table is supplied, and the substrate remaining on the bottom of the cutting groove is removed by etching, and the dividing groove along the division planned line is used. A plasma etching step for dividing the substrate;
After performing the plasma etching step, supply a gas containing ozone to the back side of the wafer, and remove at least part of the functional layer containing the resin exposed at the bottom of the dividing groove; and
A wafer processing method comprising, after the functional layer etching step, a step of extending the protective member to expand and rupturing the functional layer along the division line with the removed portion as a rupture starting point.   The wafer processing method according to claim 1, further comprising a finish grinding step of grinding the back surface of the wafer to obtain a finished thickness after the plasma etching step.   The wafer processing method according to claim 1, further comprising a preliminary grinding step of pregrinding the back surface of the wafer before the plasma etching step.

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