JP7106382B2 - Wafer processing method - Google Patents

Description

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

It is known that a semiconductor wafer made of a silicon substrate or the like is divided into individual device chips, so that a processing method using a cutting blade or a laser beam is applied. These processing methods divide the wafer into device chips by processing lines to be divided (streets) one by one. With the miniaturization of electronic equipment in recent years, device chips have become lighter, thinner and smaller, and cost has been reduced. . When manufacturing small-sized device chips, the number of dividing lines for one wafer increases dramatically, and processing one line at a time results in a long processing time.

Therefore, a technique called plasma dicing has been developed in which all the dividing lines of the wafer are collectively processed (see, for example, Patent Document 1). The plasma dicing disclosed in Patent Document 1 removes areas other than the masked area by plasma etching, and performs processing in wafer units. Therefore, even if the number of lines to be divided is increased, the processing time is dramatically shortened. There is an effect that it does not become long.

However, the plasma dicing disclosed in Patent Document 1 requires the preparation of precise masks that match the dividing lines of each wafer in order to expose only the areas to be removed by etching. See Document 2 and Patent Document 3).

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

However, in particular, the masks shown in Patent Documents 2 and 3 have high costs and high difficulties compared to cutting and the like, such as suppressing manufacturing costs and manufacturing man-hours and establishing techniques for aligning masks. was left.

SUMMARY OF THE INVENTION 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 that enables plasma etching while suppressing costs.

In order to solve the above-described problems and achieve the object, the wafer processing method of the present invention provides a method of dividing a wafer having functional layers laminated on the surface of a substrate and forming a plurality of devices into partitions for partitioning the plurality of devices. A method for processing a wafer to be divided along a predetermined line, comprising: a base attachment step of attaching a base having rigidity to the functional layer side of the front surface of the wafer; and cutting the back surface of the wafer with a cutting blade. a cutting step of forming cut grooves of a depth not reaching the functional layer in the substrate along the dividing line; holding the base side of the wafer with a chuck table of a plasma etching chamber; a plasma etching step of supplying a plasma gas to the back side of the wafer to etch and remove the substrate remaining at the bottom of the cutting groove, and dividing the substrate along the dividing line; After performing the above, the wafer is held on the base side by a chuck table of a laser processing unit, and the focal point of the laser beam from the back side of the wafer is positioned on the bottom of the etched groove and irradiated, and the function and a functional layer cutting step of cutting the layer.

In the wafer processing method, the base may be formed from any one of an adhesive tape, a glass substrate, a ceramics substrate, and a resin plate, the substrate of which is made of polyethylene terephthalate.

In the wafer processing method, after the functional layer cutting step, a tape attaching step of attaching an adhesive tape to the back surface of the wafer, and a peeling step of peeling off the base from the functional layer side of the wafer; may be provided.

In the wafer processing method, the base may be adhered to the wafer with an adhesive whose adhesive strength is reduced by an external stimulus.

The wafer processing method may include, after the plasma etching step, a finish grinding step of grinding the back surface of the wafer held on the base side by a chuck table of a grinding unit to give the wafer a finished thickness.

The wafer processing method may include, prior to the plasma etching step, a pre-grinding step of pre-grinding the back surface of the wafer whose base side is held by a chuck table of a grinding unit.

In the wafer processing method, after the plasma etching step, a die attach film attaching step of attaching a die attach film to the back surface of the wafer; and a die attach film splitting step of splitting the touch film.

In the wafer processing method, the die attach film is laminated with an adhesive tape and adhered to the back surface of the wafer fixed to the base. A peeling step of peeling the base from the functional layer side of the substrate may be provided.

The wafer processing method of the present invention has the effect of enabling plasma etching while suppressing costs.

FIG. 1 is a perspective view showing an example of a wafer to be processed by a wafer processing method according to a first embodiment. FIG. 2 is a flow chart showing the flow of the wafer processing method according to the first embodiment. FIG. 3 is a perspective view showing a state in which the functional layer side of the wafer and the adhesive material on the base face each other in the base bonding step of the wafer processing method shown in FIG. 4 is a perspective view showing a state in which a base is attached to the functional layer of the wafer in the base attachment step of the wafer processing method shown in FIG. 2. FIG. FIG. 5 is a side view showing a cutting step of the wafer processing method shown in FIG. 2 in a partial cross section. FIG. 6 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. 7 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. FIG. 8 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. 9 is a cross-sectional view showing a functional layer cutting step of the wafer processing method shown in FIG. FIG. 10 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. 11 is a side sectional view showing the finish grinding step of the wafer processing method shown in FIG. 12 is a side cross-sectional view showing a die attach film attaching step of the wafer processing method shown in FIG. 2. FIG. 13 is a side cross-sectional view showing a delamination step of the wafer processing method shown in FIG. 2. FIG. FIG. 14 is a cross-sectional view showing a die attach film dividing step of the wafer processing method shown in FIG. FIG. 15 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. 16 is a side cross-sectional view showing a delamination step of the wafer processing method according to the second embodiment. FIG. 17 is a flow chart showing the flow of the wafer processing method according to the third embodiment. 18 is a side sectional view showing a pre-grinding step of the wafer processing method shown in FIG. 17. FIG. 19 is a cross-sectional view of the main part of the wafer after the pre-grinding step of the wafer processing method shown in FIG. 17. FIG. FIG. 20 is a cross-sectional view of a main part of the wafer after the plasma etching step of the wafer processing method according to the fourth embodiment. FIG. 21 is a cross-sectional view showing the configuration of an etching apparatus used in the plasma etching step of the wafer processing method according to the fifth embodiment.

A form (embodiment) 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. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions, or changes in configuration can be made without departing from the gist 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 showing an example of a wafer to be processed by a wafer processing method according to a first embodiment. FIG. 2 is a flow chart showing the flow of the wafer processing method according to the first embodiment.

The wafer processing method according to the first embodiment is the processing method for the wafer 1 shown in FIG. In Embodiment 1, the wafer 1 is a disk-shaped semiconductor wafer or optical device wafer having a substrate 2 made of silicon, sapphire, gallium arsenide, or the like. As shown in FIG. 1, the wafer 1 has a plurality of devices 5 formed by laminating a functional layer 4 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 polymer film such as polyimide or parylene. ing. A functional layer 4 is laminated on the surface 3 of the substrate 2 .

The devices 5 are formed in respective regions partitioned by a plurality of intersecting dividing lines 6 on the surface 3 . That is, the planned division line 6 divides the plurality of devices 5 . The circuits that make up device 5 are supported by functional layer 4 . In Embodiment 1, the device 5 is smaller than the device separated from the wafer 1 by cutting, and has a size of about 1 mm×1 mm, for example. Moreover, at least one of a metal film (not shown) and a TEG (Test Element Group) may be formed on the front surface 3 side of the substrate 2 in at least a part of the dividing line 6 of the wafer 1 . The TEG is an evaluation element for finding design and manufacturing problems that occur in the device 5 .

The wafer processing method according to the first embodiment is a method of dividing the wafer 1 into individual devices 5 along dividing lines 6 and thinning the devices 5 to a finished thickness of 100 . The wafer processing method includes, as shown in FIG. 2, a base attachment step ST1, a cutting step ST2, a plasma etching step ST3, a functional layer cutting step ST4, a finish grinding step ST5, and a tape attachment step. It includes a die attach film sticking step ST6, a peeling step ST7, and a die attach film dividing step ST8.

(Base sticking step)
FIG. 3 is a perspective view showing a state in which the functional layer side of the wafer and the adhesive material on the base face each other in the base bonding step of the wafer processing method shown in FIG. 4 is a perspective view showing a state in which a base is attached to the functional layer of the wafer in the base attachment step of the wafer processing method shown in FIG. 2. FIG.

The base sticking step ST1 is a step of sticking a rigid base 200 on the functional layer 4 side of the surface 3 of the substrate 2 of the wafer 1 . In the present invention, having rigidity means that the amount of expansion and contraction is a predetermined amount or less. It shows that the base 200 does not deform more than a predetermined amount due to its own weight, etc., and has sufficient rigidity to maintain a shape similar to that when placed on a flat surface. In Embodiment 1, the base 200 is formed in a disk shape having an outer diameter equal to or larger than the outer diameter of the wafer 1, and is any one of a glass substrate made of glass, a ceramic substrate made of ceramics, and a resin plate made of resin. In addition, in the first embodiment, the surface of the base 200, as shown in FIG. 3, is hardened by at least one external stimulus of UV (ultraviolet) rays, heat, electric field, and chemical agent, thereby reducing adhesion. Material 201 is applied all over. If the adhesive 201 is to be cured by being irradiated with ultraviolet light, which is an external stimulus, the base 200 is preferably made of a transparent or translucent material so as to have translucency. desirable.

In the first embodiment, in the base attachment step ST1, as shown in FIG. 3, the functional layer 4 laminated on the surface 3 of the substrate 2 of the wafer 1 and the adhesive 201 applied to the substrate 2 are opposed to each other. . In the first embodiment, in the base attachment step ST1, the functional layer 4 is attached to the adhesive 201, and the base 200 is attached to the wafer 1 with the adhesive 201, as shown in FIG. In the wafer processing method, once the base 200 is adhered to the functional layer 4 side of the wafer 1, the process proceeds to cutting step ST2.

(cutting step)
FIG. 5 is a side view showing a cutting step of the wafer processing method shown in FIG. 2 in a partial cross section. FIG. 6 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 device 10 shown in FIG. This is the step of forming on the substrate 2 . In Embodiment 1, in the cutting step ST2, as shown in FIG. Then, the functional layer 4 side of the wafer 1 is held by suction through the base 200 . In the cutting step ST2, an infrared camera (not shown) of the cutting device 10 images the rear surface 7 of the wafer 1 to detect the dividing lines 6, and performs alignment for aligning the positions of the wafer 1 and the cutting blades 12 of the respective cutting units 11. carry out

In the cutting step ST2, the wafer 1 and the cutting blades 12 of the respective cutting units 11 are moved relatively along the dividing lines 6, and the cutting blades 12 are caused to cut into the back surface 7 of the wafer 1. A cutting groove 300 is formed. The thickness of the cutting blade 12 (hereinafter referred to as 12-1) of one cutting unit 11 (hereinafter referred to as 11-1) of the pair of cutting units 11 of the cutting device 10 used in Embodiment 1 is , is thicker than the thickness of the cutting blade 12 (hereinafter referred to as 12-2) of the other cutting unit 11 (hereinafter referred to as 11-2). In the cutting step ST2 of Embodiment 1, the cutting blade 12-1 of one of the cutting units 11-1 cuts the back surface 7 by 100 to the finishing thickness to form the first cutting groove 301 in 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 cuts into the back surface 7 by 100 to the finishing thickness. The cutting blade 12-1 may be cut into the back surface 7 to a depth shallower than the finished thickness 100, and it is desirable to leave an uncut portion thicker than the finished thickness 100 on the groove bottom side.

In the cutting step ST2, after forming the first cutting groove 301, the cutting blade 12-2 of the other cutting unit 11-2 is caused to cut into the groove bottom 303 of the first cutting groove 301, thereby cutting the first cutting groove 301. A thin second cut groove 302 is formed in the groove bottom 303 of the first cut groove 301 . In the cutting step ST2, a first cutting groove 301 and a second cutting groove 302 are formed. is formed to facilitate the penetration of the plasmatized etching gas into the cutting groove 300 in the plasma etching step ST3. In addition, in Embodiment 1, the cut groove 300 is composed of the first cut groove 301 and the second cut groove 302 . In the wafer processing method, as shown in FIG. 6, once the first cutting grooves 301 and the second cutting grooves 302 are formed on the back surface 7 side of all the dividing lines 6 of the wafer 1, the process proceeds to the plasma etching step ST3. In Embodiment 1, in the cutting step ST2, a so-called step cut is performed in which the wafer 1 is cut with the thick cutting blade 12-1 and then with the thin cutting blade 12-2. A so-called single cut, in which one cutting blade is used for cutting, may be performed.

(plasma etching step)
FIG. 7 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. FIG. 8 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, the chuck table 21 in the plasma etching chamber 25 of the etching apparatus 20 shown in FIG. Then, the substrate 2 remaining on the bottom 304 (shown in FIG. 6) of the cutting groove 300 is etched away and the substrate 2 is divided along the dividing line 6 .

In the plasma etching step ST3, the control unit 22 of the etching apparatus 20 operates the gate operating unit 23 to move the gate 24 downward in FIG. Next, the wafer 1 subjected to the cutting step ST2 is transferred through the opening 26 to the sealed space 27 in the plasma etching chamber 25 by a carrying-in/out means (not shown). The functional layer 4 side of the wafer 1 is placed on 21 (electrostatic chuck, ESC: Electrostatic chuck) via a base 200 . At this time, the control unit 22 operates the elevation drive unit 30 to raise the upper electrode 31 . The control unit 22 applies electric power to the electrodes 32 and 33 provided in the workpiece holding portion 29 to suck and hold the wafer 1 on the chuck table 21 .

The control unit 22 activates the gate actuation unit 23 to move the gate 24 upward and close the opening 26 of the plasma etching chamber 25 . The control unit 22 operates the elevation drive unit 30 to lower the upper electrode 31 so that the wafer 1 held on the chuck table 21 forming the lower electrode 28 and the lower surface of the gas ejection part 34 forming the upper electrode 31 are separated. The distance between the electrodes is positioned 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 closed space 27 in the plasma etching chamber 25 to maintain the pressure of the closed space 27 at a predetermined pressure, and operates the coolant supply unit 36. Helium gas, which is a coolant, is circulated through a coolant introduction passage 37, a cooling passage 38, and a coolant discharge passage 39 provided in the lower electrode 28 to suppress abnormal temperature rise of the lower electrode 28. FIG.

Next, the control unit 22 performs an etching step of supplying plasmatized _SF6 gas to the wafer 1 to etch the entire back surface 7 of the wafer 1 and advancing the cutting grooves 300 toward the front surface 3 of the substrate 2. , an etching step, followed by a film deposition step of supplying a plasmatized C ₄ F ₈ gas to the wafer 1 to deposit a film on the back surface 7 of the wafer 1, the inner surfaces of the cut grooves 301 and 302, and the bottom 304 of the cut groove 300. Repeat alternately. Note that the etching step after the coating deposition step removes the coating on the bottom 304 of the cut groove 300 and etches the bottom 304 of the cut groove 300 . Thus, the plasma etching step ST3 plasma-etches the wafer 1 by the so-called Bosch method.

In the etching step, the control unit 22 operates the SF ₆ gas supply unit 40 to supply SF ₆ gas, which is an etching gas, from the plurality of ejection ports 41 of the upper electrode 31 onto the chuck table 21 of the lower electrode 28. It is ejected toward the wafer 1. Then, the control unit 22 applies high-frequency power for generating and maintaining plasma from the high-frequency power supply 42 to the upper electrode 31 while supplying _SF6 gas for plasma generation, and draws ions from the high-frequency power supply 42 to the lower electrode 28. apply high-frequency power for As a result, an isotropic plasmatized etching gas composed of _SF6 gas is generated in the space between the lower electrode 28 and the upper electrode 31, and this plasmatized etching gas is drawn into the wafer 1, thereby 1, the inner surfaces of the grooves 301 and 302 and the bottom 304 of the groove 300 are etched to advance the groove 300 toward the 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 supply C ₄ F ₈ gas, which is an etching gas, from the plurality of ejection ports 41 of the upper electrode 31 to the chuck table 21 of the lower electrode 28 . It is ejected toward the wafer 1 held above. 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 C ₄ F ₈ gas for plasma generation, and ions from the high-frequency power source 42 to the lower electrode 28 . RF power is applied to pull in the As a result, a plasmatized 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 plasmatized etching gas is drawn into the wafer 1 to coat the wafer 1 . deposit.

In the plasma etching step ST3, the control unit 22 presets the number of times the etching step and the film deposition step are repeated according to the depth of the cutting groove 300, that is, the thickness of the wafer 1. FIG. In the plasma etching step ST3, the wafer 1, on which the etching step and the film deposition step have been repeated a preset number of times, the wafer 1 is etched all over the back surface 7 by the initial etching step to a thickness 101, as shown in FIG. thinned. Further, after repeating the etching step and the film deposition step for a preset number of times, the wafer 1 is etched and removed in the etching step to remove the substrate 2 remaining on the bottom 304 of the cutting groove 300, as shown in FIG. A groove 300 reaches the functional layer 4 . The substrate 2 of the wafer 1 is divided by the cut grooves 300 , the functional layer 4 is exposed in the cut grooves 300 , and the functional layer 4 remains at the bottom of the cut grooves 300 . In the wafer processing method, after the plasma etching step ST3 is completed, the wafer 1 is unloaded from the plasma etching chamber 25 while being held on the base 200, and proceeds to the functional layer cutting step ST4. FIG. 8 shows an example in which the wafer 1 after the plasma etching step ST3 removes the substrate 2 at the bottom of the cutting groove 300, but in the present invention, the substrate 2 is slightly removed from the bottom of the cutting groove 300. You can stay.

(Functional layer cutting step)
FIG. 9 is a cross-sectional view showing a functional layer cutting step of the wafer processing method shown in FIG. FIG. 10 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 performing the plasma etching step ST3, the base 200 side of the wafer 1 is held by the holding surface 54 of the chuck table 53 of the laser processing unit 50 shown in FIG. In the step of irradiating the functional layer 4 with a laser beam 51 having a wavelength that is absorptive from the laser beam 51 positioned at the bottom of the etched groove 300 and cutting the functional layer 4 along the groove 300. be.

In the functional layer cutting step ST4, the laser processing unit 50 holds the functional layer 4 side of the wafer 1 on the holding surface 54 of the chuck table 53 via the base 200, and as shown in FIG. While relatively moving the chuck table 53 along the dividing line 6, the laser beam 51 having a wavelength (for example, 355 nm) that is absorptive to the functional layer 4 is directed from the laser beam irradiation unit 52 to the focal point 51-1. A laser beam 51 is applied to the functional layer 4 exposed at the bottom of the cut groove 300 . In the functional layer cutting step ST4, the functional layer 4 exposed at the bottom of the cutting groove 300 is ablated along each dividing line 6, the functional layer 4 exposed at the bottom of the cutting groove 300 is cut, and the wafer 1 is obtained. are divided into individual devices 5 . In addition, in the functional layer cutting step ST4, the metal film and the TEG formed on the dividing lines 6 (not shown) are also divided. In the wafer processing method, as shown in FIG. 10, when the functional layer 4 exposed at the bottom of the cut groove 300 is divided on all the dividing lines 6, the process proceeds to the finish grinding step ST5.

(finish grinding step)
FIG. 11 is a side sectional view showing the finish grinding step of the wafer processing method shown in FIG. In the finish grinding step ST5, after the plasma etching step ST3 and the functional layer cutting step ST4, the back surface 7 of the wafer 1 held on the base 200 side by the holding surface 62 of the chuck table 61 of the finish grinding unit 60, which is a grinding unit, is ground. and the wafer 1 is made to have a finished thickness of 100.

In the finish grinding step ST5, the finish grinding unit 60 suction-holds the functional layer 4 side of the wafer 1 on the holding surface 62 of the chuck table 61 via the base 200. FIG. In the finish grinding step ST5, as shown in FIG. 11, the finish grinding unit 60 rotates the grinding wheel 64 for finish grinding by the spindle 63 and supplies grinding water while rotating the chuck table 61 about its axis. , the finish grinding grindstone 65 is brought close to the chuck table 61 at a predetermined feed rate to finish grind the back surface 7 of the wafer 1 , that is, the device 5 . In the finish grinding step ST5, the wafer 1, that is, the device 5 is ground to a finished thickness of 100. As shown in FIG. In the finish grinding step ST5, when the wafer 1, that is, the device 5 is ground to a finished thickness of 100, the first cut groove 301 is removed and the step between the first cut groove 301 and the second cut groove 302 is removed. be done. In the wafer processing method, when the finish grinding unit 60 thins the wafer 1, that is, the device 5 to a finished thickness of 100, the process proceeds to the die attach film bonding step ST6.

(Die attach film attachment step)
12 is a side cross-sectional view showing a die attach film attaching step of the wafer processing method shown in FIG. 2. FIG. The die attach film attaching step ST6 is a step of attaching the die attach film 210 to the back surface 7 of the wafer 1 after the plasma etching step ST3, the functional layer cutting step ST4 and the finish grinding step ST5.

In the die attach film attaching step ST6, the die attach film 210 for attaching the device 5 is attached to the back surface 7 of the wafer 1, ie, the device 5, which has been finish ground in the finish grinding step ST5. In the die attach film attaching step ST6, as shown in FIG. 12, the wafer 1 attached to the base 200 and the annular frame 202 whose inner diameter is larger than the outer diameter of the wafer 1 are placed coaxially. . In the die attach film attaching step ST6, as shown in FIG. 12, the die attach film 210 laminated on the dicing tape 211, which is an adhesive tape, is attached to the back surface 7 of the wafer 1, and the dicing tape 211 is attached to the annular frame 202. affixed to In this way, in the die attach film attaching step ST6, the dicing tape 211 is attached to the back surface 7 of the wafer 1 via the die attach film 210, and the die attach film 210 and the dicing tape 211 are stacked on the base. It is attached to the back surface 7 of the wafer 1 fixed to 200 . In the wafer processing method, once the die attach film 210 is adhered to the rear surface 7 of the wafer 1, the process proceeds to the peeling step ST7.

(Peeling step)
13 is a side cross-sectional view showing a delamination step of the wafer processing method shown in FIG. 2. FIG. The peeling step ST7 is a step of peeling off the base 200 from the functional layer 4 side of the wafer 1, and is a step performed before the die attach film dividing step ST8.

In the peeling step ST7, as shown in FIG. 13, the laser processing unit 70 holds the rear surface 7 side of the wafer 1 on the holding surface 72 of the chuck table 71 with the dicing tape 211 by suction. In the peeling step ST7, the rear surface 7 side of the wafer 1 is held by suction on the holding surface 72 of the chuck table 71 to regulate the movement of the wafer 1, that is, the device 5, and then the adhesive 201 is given an external stimulus to harden. to reduce the adhesive strength of the adhesive 201 . In the separation step ST7, the base 200 is separated from the functional layer 4 on the front surface 3 side of the substrate 2 of the wafer 1 . In the wafer processing method, when the base 200 is separated from the functional layer 4 side of the wafer 1, the process proceeds to the die attach film division step ST8.

(Die attach film division step)
FIG. 14 is a cross-sectional view showing a die attach film dividing step of the wafer processing method shown in FIG. FIG. 15 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 210 by irradiating the die attach film 210 with the laser beam 74 shown in FIG.

In the die attach film dividing step ST8, as shown in FIG. The die attach film 210 exposed in the cut groove 300 is irradiated with a laser beam 74 having a wavelength (eg, 355 nm) that is absorptive to the film 210 . In the die attach film dividing step ST8, the die attach film 210 exposed within the cut grooves 300 is ablated along each dividing line 6 to divide the die attach film 210 exposed within the cut grooves 300 . As shown in FIG. 15, the wafer processing method ends when the die attach film 210 exposed in the cutting grooves 300 is split along all the splitting lines 6 . After that, the device 5 is picked up from the dicing tape 211 by a pickup (not shown) together with the die attach film 210 .

In the wafer processing method according to the first embodiment, after forming the cutting grooves 300 from the back surface 7 along the dividing lines 6 in the cutting step ST2, plasma etching is performed from the back surface 7 side in the plasma etching step ST3 to form the cutting grooves. Since the wafer 1 is divided by advancing the 300 toward the surface 3 of the substrate 2, plasma dicing without a mask can be realized. For this reason, the wafer processing method eliminates the need for an expensive mask in the method of processing the wafer 1 having the devices 5 that are smaller than the devices that are divided by cutting and are suitable for being divided by plasma etching. . As a result, the wafer processing method can plasma etch the wafer 1 to separate the wafer 1 into individual devices 5 while controlling costs.

Further, in the wafer processing method, since the wafer 1 divided into individual devices 5 is fixed to the rigid base 200 in the functional layer cutting step ST4, the wafer to the process after the functional layer cutting step ST4 1 and during the process after the functional layer cutting step ST4, the devices do not rub against each other, and the process can be easily performed.

Further, in the wafer processing method, the back surface 7 side of the wafer 1 is held by suction on the holding surface 72 of the chuck table 71 via the dicing tape 211 or the like in the separation step ST7, and the base 200 is separated. 2 can be prevented from being displaced when the devices 5 are separated from each other. In addition, in the die attach film dividing step ST8, the back surface 7 of the wafer 1 is held by suction on the holding surface 72 of the chuck table 71 via the dicing tape 211 or the like, and exposed at the bottom of the cut groove 300. A laser beam 74 is applied to the die attach film 210 .

Therefore, in the wafer processing method, when the die attach film 210 adhered to the back surface 7 of the wafer 1 is split by the laser beam 74, the device 5 is fixed to the chuck table 71 of the laser processing unit 70 so that the position of the device 5 does not move. After that, the base 200 is peeled off, and the distortion of the cut groove 300 can be suppressed. As a result, in the die attach film dividing step ST8, the wafer processing method has the effect of making it very easy to set the processing positions (that is, alignment) of the laser processing unit 70, etc., and to reduce the time required for alignment. .

Further, in the wafer processing method, the base 200 is attached to the functional layer 4 side in the base attaching step ST1 before the cutting step ST2 and the finish grinding step ST5. For this reason, it is possible to prevent contamination from adhering to the device 5 during the cutting step ST2 and the finish grinding step ST5.

In the wafer processing method, in the functional layer cutting step ST4, the functional layer 4 remaining on the groove bottom of the cut groove 300 is irradiated with the laser beam 51 to be divided, so that the functional layer 4 such as a Low-k film is laminated. A single wafer 1 can be separated into individual devices 5 . In the wafer processing method, the base 200 is attached to the functional layer 4 side in the base attaching 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 bottom of the cutting groove 300 is irradiated, it is possible to suppress adhesion of debris generated during the ablation process to the device 5 .

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

Further, in the wafer processing method, in the cutting step ST2, by forming a cutting groove 300 deeper than the finished thickness of 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 reaches the finished thickness of 100, the cut groove 300 with a desired depth can be formed.

In addition, in the wafer processing method, in order to divide the substrate 2 along the dividing lines 6 in the plasma etching step ST3, the side surfaces of the divided devices 5 are removed by plasma etching. For this reason, the wafer processing method also has the effect that chipping due to cutting does not remain on the side surfaces of the individually divided devices 5, and devices 5 with high bending strength can be manufactured.

Further, in the wafer processing method, in the finish grinding step ST5, the back surface 7 of the wafer 1 is ground to remove the step between the first cut groove 301 and the second cut groove 302 and thin it to a desired thickness. Therefore, a device 5 with predetermined dimensions can be obtained.

Moreover, since the wafer processing method includes the die attach film bonding step ST6 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. 16 is a side cross-sectional view showing a delamination step of the wafer processing method according to the second embodiment. In addition, FIG. 16 attaches|subjects the same code|symbol to the same part as Embodiment 1, and abbreviate|omits description.

The wafer processing method according to the second embodiment is the same as that of the first embodiment except that the base 200 is an adhesive tape 220 including a base material 200-2 and an adhesive material 201. FIG. The base material 200-2 is made of PET (Polyethylene Terephthalate) resin. The adhesive tape 220 has rigidity like the base 200 of the first embodiment. The adhesive 201 is laminated over one surface of the base material 200-2. In addition, in Embodiment 2, the adhesive tape 220 is formed in a disk shape having substantially the same diameter as the wafer 1 . As for the adhesive tape 220, the adhesive material 201 is attached to the functional layer 4 side of the surface 3 of the substrate 2 of the wafer 1 in the base attachment step ST1, as in the first embodiment. In the peeling step ST7, the adhesive tape 220 is peeled off from the functional layer 4 side of the front surface 3 of the wafer 1 whose rear surface 7 side is held by suction on the holding surface 72 of the chuck table 71 as in the first embodiment, as shown in FIG. be. In the second embodiment, in the peeling step ST7, one end of the adhesive tape 220 is moved along the surface 3 of the wafer 1, so that the adhesive tape 220 is peeled off from the functional layer 4 on the surface 3 side of the wafer 1. be.

In the wafer processing method according to the second embodiment, after the cutting grooves 300 are formed along the dividing lines 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, so a mask is unnecessary. plasma dicing can be realized. 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 costs, as in the first embodiment.

Further, in the wafer processing method, since the wafer 1 is fixed to the rigid base 200 in the base bonding step ST1, the wafer 1 is transferred to the process after the functional layer cutting step ST4 as in the first embodiment. This can be easily performed without the devices rubbing against each other during the process after the functional layer cutting step ST4.

Further, in the wafer processing method, the adhesive tape 220 is peeled off from the wafer 1 whose back surface 7 side is suction-held by the holding surface 72 of the chuck table 71 in the peeling step ST7. In ST8, the setting of the processing positions of the laser processing unit 70 (that is, alignment) is very easy, and the time required for alignment can be reduced.

[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 flow chart showing the flow of the wafer processing method according to the third embodiment. 18 is a side sectional view showing a pre-grinding step of the wafer processing method shown in FIG. 17. FIG. 19 is a cross-sectional view of the main part of the wafer after the pre-grinding step of the wafer processing method shown in FIG. 17. FIG. 17, 18 and 19, the same reference numerals are given to the same parts as in the first embodiment, and the description thereof is omitted.

The wafer processing method according to Embodiment 3 is the same as Embodiment 1, except that a preliminary grinding step ST10 is provided, as shown in FIG. The preliminary grinding step ST10 is a step of grinding in advance the back surface 7 of the wafer 1 held on the base 200 side by the chuck table 81 of the grinding unit 80 before the plasma etching step ST3. In Embodiment 3, the wafer processing method performs the preliminary grinding step ST10 after the base bonding step ST1 and before the cutting step ST2. It may be performed before the base sticking step ST1 or after the cutting step ST2.

In the preliminary grinding step ST10, the grinding unit 80 suction-holds the functional layer 4 side of the wafer 1 on the holding surface 82 of the chuck table 81 via the base 200. FIG. In the preliminary grinding step ST10, as shown in FIG. 18, the grinding wheel 84 for rough grinding is rotated by the spindle 83, and while the chuck table 81 is rotated around its axis, grinding water is supplied and the grindstone 85 for rough grinding is supplied. is brought close to the chuck table 81 at a predetermined feed rate, the back surface 7 of the wafer 1 is roughly ground by the grindstone 85 for rough grinding. The rough-grinding whetstone 85 is a grinding whetstone having abrasive grains larger than those of the finish-grinding whetstone 65 .

In the pre-grinding step ST10, as shown in FIG. 17, the wafer 1 is ground until it becomes equal to or greater than the sum of the finished thickness 100 and the thickness 101 removed in the plasma etching step ST3. In the third embodiment, the wafer processing method advances to the cutting step ST2 after the wafer 1 is ground to a thickness equal to or greater than the sum of the finished thickness 100 and the thickness 101 removed in the plasma etching step ST3. In the present invention, in the preliminary grinding step ST10, the wafer 1 is preferably thinned to a thickness approximately equal to the sum of the finished thickness 100 and the thickness 101 removed in the plasma etching step ST3.

In the wafer processing method according to the third embodiment, after the cutting grooves 300 are formed along the dividing lines 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, so a mask is unnecessary. plasma dicing can be realized. 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 costs, as in the first embodiment.

In the wafer processing method according to the third embodiment, since the preliminary grinding step ST10 is performed before the plasma etching step ST3 to thin the wafer 1, the removal amount of the substrate 2 of the wafer 1 during the plasma etching step ST3 is can be suppressed. As a result, the wafer processing method according to the third embodiment can suppress the amount of so-called outgas generated in the plasma etching step ST3.

In the wafer processing method according to the third embodiment, the back surface 7 of the wafer 1 is ground by performing the preliminary grinding step ST10 before the cutting step ST2. Even if the surface has a satin 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 third embodiment, in the cutting step ST2, the cutting blades 12-1 and 12-2 are scheduled to be separated when alignment is performed based on the image of the surface of the wafer 1 captured by the infrared camera. Positional deviation from the line 6 can be suppressed.

[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 of the main part of the wafer after the plasma etching step of the wafer processing method according to the fourth embodiment. In addition, FIG. 18 attaches|subjects the same code|symbol to the same part as Embodiment 1, and abbreviate|omits description.

The wafer processing method according to the fourth embodiment is the same as that of the first embodiment except that the wafer 1 is etched by anisotropic etching instead of the Bosch method in the plasma etching step ST3. In the wafer processing method according to the fourth embodiment, in the plasma etching step ST3, the shapes of the back surface 7 of the wafer 1 and the cutting grooves 300 before etching indicated by the dotted line in FIG. Then, the entire substrate 2 is etched from the back surface 7 side to divide the substrate 2 along the dividing lines 6. - 特許庁

In the wafer processing method according to the fourth embodiment, after the cutting grooves 300 are formed along the dividing lines 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, so a mask is unnecessary. plasma dicing can be realized. 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 costs, as in the first embodiment.

In the wafer processing method according to the fourth embodiment, the substrate 2 of the wafer 1 is etched from the back surface 7 side by anisotropic etching in the plasma etching step ST3. 2 can be thinned. As a result, the method for processing the wafer 1 can suppress the grinding amount of the substrate 2 in the finish grinding step ST5.

It should be noted that the wafer processing method according to the fourth embodiment may perform the preliminary grinding step ST10 as in the third embodiment.

[Embodiment 5]
A wafer processing method according to Embodiment 5 of the present invention will be described with reference to the drawings. FIG. 21 is a cross-sectional view showing the configuration of an etching apparatus used in the plasma etching step of the wafer processing method according to the fifth embodiment. In addition, FIG. 21 attaches|subjects the same code|symbol to the same part as Embodiment 1, and abbreviate|omits description.

The wafer processing method according to the fifth embodiment is the same as that of the first embodiment except that the etching apparatus 20-5 used in the plasma etching step ST3 shown in FIG.

The etching apparatus 20-5 does not apply high-frequency power to the electrodes 28 and 31 to generate plasma of the etching gas or the like in the closed space 27, but rather plasmifies the etching gas or the like into the closed space 27 in the plasma etching chamber 25. It is a remote plasma type plasma etching apparatus to be introduced. As shown in FIG. 21, the etching apparatus 20-5 is connected to a plasma etching chamber 25 through a pipe 45 supplied with an inert gas from an inert gas supply unit (not shown). The inert gas supplied by the inert gas supply unit includes rare gases such as argon gas (Ar) and helium gas (He), and rare gases such as nitrogen gas (N ₂ ) and hydrogen gas (H ₂ ). can be composed of a mixed gas or the like in which

Also, in the etching apparatus 20-5, as shown in FIG. 21, a supply pipe 46 to which the etching gas is supplied from the gas supply units 40 and 43 is connected through the upper wall of the plasma etching chamber 25. An electrode 47 for applying high-frequency power to the etching gas flowing through the supply pipe 46 is provided. The supply pipe 46 introduces the etching gas supplied from the gas supply units 40 and 43 into the closed space 27 inside the plasma etching chamber 25 . The electrode 47 receives high-frequency power from the high-frequency power supply 42 and turns the gas flowing through the supply pipe 46 into plasma. The etching apparatus 20-5 also includes a dispersing member 48 that disperses the plasmatized gas supplied from the supply pipe 46 to the sealed space 27. As shown in FIG.

In the wafer processing method according to Embodiment 5, as in Embodiment 1, in the plasma etching step ST3, the control unit 22 of the etching device 20-5 accommodates the wafer 1 in the closed space 27 in the plasma etching chamber 25. After that, it is held on the chuck table 21 by suction. In the plasma etching step ST3 of the wafer processing method according to the fifth embodiment, the control unit 22 operates the gas exhaust unit 35 to evacuate the closed space 27 and operates the inert gas supply unit to evacuate the closed space 27. Inert gas is supplied to the inside of the closed space 27 to maintain the pressure of the sealed space 27 at a predetermined pressure, and the coolant supply unit 36 is operated to circulate helium gas, thereby suppressing abnormal temperature rise of the lower electrode 28 .

In the wafer processing method according to the fifth embodiment, in the plasma etching step ST3, the wafer 1 is plasma-etched by the Bosch method as in the first embodiment. In the etching step of the plasma etching step ST3, the control unit 22 operates the _SF6 gas supply unit 40 and applies high-frequency power for generating and maintaining plasma from the high-frequency power supply 42 to the electrode 47, thereby causing the _SF6 gas to become plasma. , and 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 attracting 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 cut grooves 301 and 302, and the bottom 304 of the cut groove 300. .

Further, in the film deposition step of the plasma etching step ST3, the control unit 22 activates the C ₄ F ₈ gas supply unit 43 to turn the C ₄ F ₈ gas into plasma with the high frequency power applied from the high frequency power supply 42 to the electrode 47, It is jetted 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 attracting 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 fifth embodiment, after the cutting grooves 300 are formed from the back surface 7 along the dividing lines 6 in the cutting step ST2, plasma etching is performed from the back surface 7 side in the plasma etching step ST3, so a mask is unnecessary. plasma dicing can be realized. 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 costs, as in the first embodiment.

Further, in the wafer processing method according to the fifth embodiment, the plasma etching step ST3 uses the remote plasma type etching device 20-5. , and reach the closed space 27 in the plasma etching chamber 25 , the substrate 2 can be divided into devices 5 even with a narrower cutting groove 300 .

Note that the wafer processing method according to the fifth embodiment may perform the preliminary grinding step ST10 as in the third embodiment.

It should be noted that the present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the gist of the present invention. For example, in the present invention, before the cutting step ST2, the functional layer 4, the metal film, and the TEG formed on the planned division line 6 may be removed by ablation by irradiating a laser beam from the surface. Further, in the present invention, when an oxide film is formed on the rear surface 7 of the wafer 1 in advance, plasma etching may be performed using this oxide film as a mask in the plasma etching step ST3. Further, in the present invention, in both the finish grinding step ST5 and the preliminary grinding step ST10, after the back surface 7 of the wafer 1 is roughly ground using the grindstone 85 for rough grinding, the back surface 7 of the wafer 1 is ground using the grindstone 65 for finish grinding. Finish grinding may be performed, the back surface 7 of the wafer 1 may be only rough ground, or the back surface 7 of the wafer 1 may be only finish ground. Also, the present invention is not limited to the sizes of the device 5 described in the above embodiments.

REFERENCE SIGNS LIST 1 wafer 2 substrate 3 front surface 4 functional layer 5 device 6 division line 7 rear surface 12, 12-1, 12-2 cutting blade 21 chuck table 25 plasma etching chamber 50 laser processing unit 51 laser beam 51-1 focal point 53 chuck table 60 finish grinding unit (grinding unit)
61 Chuck table 74 Laser beam 80 Grinding unit 81 Chuck table 100 Finished thickness 200 Base 200-2 Base material 201 Adhesive 210 Die attach film 211 Dicing tape (adhesive tape)
220 adhesive tape (base)
300 Cutting groove 304 Bottom ST1 Base sticking step ST2 Cutting step ST3 Plasma etching step ST4 Functional layer cutting step ST5 Finish grinding step ST6 Die attach film sticking step (tape sticking step)
ST7 peeling step ST8 die attach film dividing step ST10 preliminary grinding step

Claims (8)

A wafer processing method for dividing a wafer, in which a plurality of devices are formed by laminating a functional layer on the surface of a substrate, along division lines that divide the plurality of devices, comprising:
a base sticking step of sticking a rigid base on the functional layer side of the surface of the wafer;
a cutting step of cutting a cutting blade into the back surface of the wafer to form a cutting groove having a depth not reaching the functional layer in the substrate along the dividing line;
The base side of the wafer is held by a chuck table of a plasma etching chamber, plasma gas is supplied to the back side of the wafer to etch and remove the substrate remaining on the bottom of the cutting groove, and the substrate is removed. a plasma etching step of dividing the along the planned dividing line;
After performing the plasma etching step, the base side of the wafer is held by a chuck table of a laser processing unit, and the condensing point of the laser beam from the back side of the wafer is positioned at the bottom of the etched groove and irradiated. and a functional layer cutting step of cutting the functional layer. 2. The method of processing a wafer according to claim 1, wherein said base is formed of any one of an adhesive tape made of polyethylene terephthalate, a glass substrate, a ceramics substrate, and a resin plate. 2. After the functional layer cutting step, the method further comprises a tape attaching step of attaching an adhesive tape to the back surface of the wafer, and a peeling step of peeling off the base from the functional layer side of the wafer. Item 3. A method for processing a wafer according to item 2. 4. The method of processing a wafer according to claim 1, wherein the base is adhered to the wafer with an adhesive whose adhesive strength is reduced by an external stimulus. 5. After the plasma etching step, a finish grinding step of grinding the back surface of the wafer held on the base side by a chuck table of a grinding unit to give the wafer a finished thickness is provided. A method for processing a wafer according to item 1. 6. The method according to any one of claims 1 to 5, further comprising a pre-grinding step of pre-grinding the back surface of the wafer held on the base side by a chuck table of a grinding unit before the plasma etching step. wafer processing method. a die attach film attaching step of attaching a die attach film to the back surface of the wafer after the plasma etching step;
and a die attach film dividing step of irradiating the die attach film along the cutting grooves with a laser beam to divide the die attach film. Method. The die attach film is attached to the back surface of the wafer fixed to the base while being laminated with an adhesive tape,
8. The wafer processing method according to claim 7, further comprising a peeling step of peeling off the base from the functional layer side of the wafer before performing the die attach film dividing step.

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