TWI582843B - The manufacturing method of the attached wafer - Google Patents

Description

Manufacturing method of covered wafer Field of invention

The present invention relates to a method of fabricating a wafer fabricated on a surface of a component wafer having a cover.

Background of the invention

A component such as a MEMS (Micro Electro Mechanical Systems) device or a COMS (Complementary Metal Oxide Semiconductor) image sensing device formed on a surface of a semiconductor wafer transmits signals in any layer, and each metal wiring is mainly used by The interlayer insulating film formed of SiO ₂ is insulated.

In recent years, as the structure is made finer, the distance between wirings becomes closer, and the capacitance between the wirings becomes larger. Therefore, the delay of the signal is generated, and the problem of the increase in power consumption and the like is also remarkably increased.

In order to reduce the parasitic capacitance between the layers, an interlayer insulating film which insulates between layers is formed by using a SiO ₂ insulating film in the case of forming a device (circuit), but recently, a dielectric material having a dielectric constant lower than that of the SiO ₂ insulating film has been gradually used. Rate insulation film (Low-k film).

It is also common for the interlayer insulating film to use a Low-k film in a wafer in which a MEMS element is formed or a wafer in which a CMOS image sensing element is formed.

Sometimes a MEMS element wafer or a CMOS element wafer is divided into individual element wafers by a cutting device or a laser processing apparatus, and a cover for protecting the elements is disposed on the surface of the element wafer. Conventionally, after being divided into component wafers, a lid is placed on the wafer to serve as a cap wafer.

Advanced technical literature Patent literature

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-320466

Summary of invention

After dividing into individual element wafers in the past, it is difficult to produce a cover wafer by disposing a cover on the surface of the wafer, which is labor intensive and extremely inferior in productivity. Therefore, it is considered to perform division after bonding the wafer cover on the component wafer to improve production efficiency.

However, when a laminate of a Low-k film or a TEG (Test Element Group) pattern, a passivation of SiN or a polyimide, or the like is located on a division line of the element wafer as an interlayer insulating film, there is a wafer in the wafer. After the cover is attached to the component wafer, it is difficult to divide the wafer with the laminate.

Specifically, the Low-k film is peeled off like a mica, so that, for example, when cutting with a cutting insert, the Low-k film of the element region is also peeled off, and the component may be damaged. Further, when the metal TEG pattern or the passivation film is cut by the cutting insert, clogging occurs in the cutting insert, resulting in poor cutting.

On the other hand, the laminated substrate is irradiated with a wavelength having transparency. After the laser beam is formed on the inside of the bonded wafer to form a modified layer, even if an external force is applied to the bonded wafer to be divided, there is a metal TEG pattern or a passivation film which is very difficult to be divided, and the Low-k film cannot be along The problem of splitting the layer.

The present invention has been made in view of the above, and an object of the invention is to provide a method for manufacturing a wafer which is capable of preventing a wafer to be bonded which does not interfere with the bonding of a wafer by a laminate on a predetermined line.

According to the invention of claim 1, there is provided a method of manufacturing a wafer comprising a component wafer having a component on a surface thereof and a cover plate disposed on a surface of the crystal face of the component, characterized in that the component has the following steps: a wafer preparation step of preparing a component wafer of each of the regions defined by the plurality of predetermined dividing lines formed on the surface and interleaved; and a layer removing step of irradiating the laser along the dividing line of the component wafer Removing a layered product laminated on the dividing line by a light beam; bonding a wafer forming step, after performing the layer removing step, causing the bonding member to be interposed between at least the regions surrounding the component wafer, and A wafer cover is attached to the surface of the component wafer to form a bonded wafer, and a dividing step is performed to divide the bonded wafer along the dividing line to form a wafer on the surface of the component wafer.

According to the invention of claim 2, in the invention of the first aspect, after the step of removing the laminate, the step of forming the groove is further performed before the step of forming the bonded wafer, and the step of forming the groove Cutting the component wafer with a cutting blade along the aforementioned predetermined dividing line of the component wafer, and forming a depth to the processing thickness of the component wafer The cutting groove includes the element wafer dividing step, and after performing the bonding wafer forming step, grinding the back side of the element wafer constituting the bonding wafer to thin the element The wafer is processed to have a thickness, and the cutting groove is exposed on the back surface of the element wafer to divide the element wafer into individual element wafers; and the wafer cover dividing step divides the wafer cover along the dividing line.

According to the invention of claim 1, since the laminate located on the division line of the component wafer is removed before the bonding wafer is formed, the laminate of the bonded wafer is not hindered by dividing the laminate on the predetermined line. The covered wafer is efficiently manufactured.

According to the invention of claim 2, even if the wafer wafer is thin, since the wafer cover is attached, the processing can be easily divided into the attached component wafer without being hindered.

10‧‧‧ Laser processing equipment

11‧‧‧Component Wafer

11a‧‧‧ surface

11b‧‧‧Back

12‧‧‧Working table

13‧‧‧Division line

13a‧‧‧Low-k film

14‧‧‧ concentrator

15‧‧‧ CMOS image sensing components

15A‧‧‧Component chip

16‧‧‧Laser processing ditch

17‧‧‧Component area

18‧‧‧Subsequent components

19‧‧‧ remaining areas of the periphery

20‧‧‧ wafer cover

21‧‧‧ Scotch

22,22A‧‧‧Cutting inserts

23‧‧‧ Cover

24‧‧‧Cutting trench

25‧‧‧Fixed wafer

30‧‧‧Working table

32‧‧‧ grinding unit

34‧‧‧ center axis

36‧‧·wheel seat

38‧‧‧ grinding wheel

40‧‧‧ wheel base

42‧‧‧ grinding wheel

T‧‧‧Adhesive tape

T1‧‧‧Processing thickness

1 is a perspective view of a surface side of a semiconductor wafer.

Fig. 2 is a perspective view showing a step of removing a laminate.

Fig. 3 is an exploded perspective view showing the step of forming a bonded wafer.

Figure 4 is a side view showing the grinding step inside.

Fig. 5 is a longitudinal sectional view showing a dividing step.

Fig. 6(A) is a cross-sectional view showing a step of removing a layered product in a second embodiment, and Fig. 6(B) is a cross-sectional view showing a step of removing a layered product in a third embodiment.

Fig. 7(A) shows the step of removing the laminate in the second embodiment. FIG. 7(B) is a cross-sectional view showing a step of forming a cutting groove after the step of removing the layered product of the third embodiment.

Fig. 8 is a side view showing the step of dividing the component wafer.

Figure 9 is a cross-sectional view showing the wafer cover dividing step.

Detailed description of the preferred embodiment

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to Fig. 1, a surface side perspective view of the element wafer 11 is shown. The element wafer 11 is composed of, for example, a silicon wafer having a thickness of 700 μm, and the surface 11a is formed with a lattice-shaped plural divided line (cutting track) 13 and formed in each of the fields divided by the plurality of divided planned lines 13. There is a CMOS image sensing device 15.

In the element wafer 11, a low dielectric constant insulating film (Low-k film) is used as an interlayer insulating film necessary for insulating the metal wiring. Therefore, a Low-k film is laminated on the division planned line 13.

The low dielectric constant insulating film may be a material having a lower dielectric constant than a SiO ₂ film (dielectric K=4.1) (for example, K=2.5 to 3.6), a film of an inorganic system such as SiOC or SiLK, or a polysiloxane. A film of an organic film of a copolymer film such as an amine system, a polyparaphenylene group or a polytetrafluoroethylene, or a porous cerium oxide film such as a polysiloxane containing a methyl group.

The element wafer 11 thus constructed has an element region 17 on which a CMOS image sensing element 15 is formed and a peripheral remaining region 19 around the element region 17 at a flat portion on the surface thereof. A notch 21 as a mark indicating the crystal orientation of the germanium wafer is formed on the outer periphery of the element wafer 11.

In the method for manufacturing a wafer of the present invention, first, a laminate is removed. In the step, the laser beam is irradiated along the dividing line 13 of the element wafer 11 to remove the Low-k film (layered product) laminated on the dividing line. In the laminate removal step, as shown in FIG. 2, the surface 11a of the element wafer 11 is attracted upward and held by the work chuck 12 of the laser processing apparatus.

Next, the element wafer 11 is imaged by an imaging unit (not shown) of the laser processing apparatus 10, and a calibration line for detecting the planned dividing line 13 extending in the first direction is subjected to laser processing. Next, after the work chuck 12 is rotated by 90 degrees, the same alignment is performed on the division planned line 13 extending in the second direction orthogonal to the first direction.

After the calibration is performed, the laser beam 14 is used to collect the laser beam having an absorptive wavelength (for example, 355 nm) by the concentrator 14 to illuminate the division target line 13 and to make the work chuck 12 predetermined. The machining speed is moved in the direction of the arrow X1 of the second, whereby the laser machining groove 16 is formed along the division planned line 13, and the laminated Low-k film on the division planned line 13 is removed.

In this embodiment, it is preferable to increase the beam spot diameter of the laser beam collected by the concentrator 14 on the dividing line 13 and the width of the blade of the cutting blade used in the dividing step of the post-process. In the middle, the Low-k film which is a laminate is removed.

The working chuck 12 is cut one by one in the Y-axis direction and conveyed to each other, and the Low-k film laminated on the dividing line 13 extending in the first direction is removed. Next, the working chuck 12 is rotated by 90 degrees, and the same laser processing groove 16 is formed along the dividing line 13 extending in a direction orthogonal to the dividing line 13 extending in the first direction, and the dividing line is removed. The Low-k film laminated on the 13th.

The laser processing conditions of the laminate removal step are set as follows.

Light source: YAG pulse laser or YVO ₄ pulse laser

Wavelength: 355nm

Average output: 7~10W

Repeat frequency: 100~130kHz

Processing transfer speed: 70~100mm/s

After the laminate removal step is performed, as shown in FIG. 3, a bonding wafer forming step is performed such that the bonding member 18 is interposed between the component wafers 11 surrounding the respective elements 15 and is attached to the surface 11a of the component wafer 11. The wafer cover 20 forms a bonded wafer 25.

Since the element wafer 11 of the present embodiment has a plurality of CMOS image sensing elements 15 on its surface 11a, the wafer cover 20 is made of transparent glass.

However, the wafer cover 20 used in the method of manufacturing a wafer of the present invention is not limited to glass. For example, when the element 15 is a MEMS element or the like, the wafer cover 20 may be formed of a germanium wafer or the like.

After the bonding wafer forming step is performed, the back grinding step is performed, and the back surface 11b of the element wafer 11 is ground to thin the element wafer 11 to a predetermined thickness. In the back grinding step, as shown in FIG. 4, the wafer cover 20 side of the bonded wafer 25 is sucked by the work chuck 30 of the grinding device, and the back surface 11b of the element wafer 11 is exposed.

In Fig. 4, the wheel base 36 fixed to the front end of the spindle 34 of the grinding unit 32 is a plurality of screws (not shown), and a detachable grinding wheel 38 is mounted. The grinding wheel 38 is a type in which the plurality of grinding wheels 42 are annularly disposed on the wheel base 40 The end portion (lower end portion) is formed.

In the back grinding step, the work chuck 30 is rotated in the direction indicated by the arrow a at, for example, 300 rpm, and the grinding unit transport mechanism is driven to bring the grinding wheel 42 of the grinding wheel 38 into contact with the back surface 11b of the element wafer 11.

Next, the grinding wheel 38 is conveyed downward and ground by a predetermined amount at a predetermined grinding conveyance speed.

After the back grinding step is performed, the dividing step is performed, the bonded substrate 25 is divided along the dividing line, and the wafer on which the cover 23 is placed is formed on the surface of the element wafer 15A. Before performing the dividing step, a tape attaching step is performed to attach the adhesive tape T to the wafer cover 20 of the bonded wafer 25.

Next, the infrared imaging device of the imaging unit of the cutting device is imaged by the back surface 11b side of the wafer 11, and the planned dividing line 13 is detected. The calibration is performed on the planned dividing line 13 extending in the first direction and the dividing line 13 extending in the second direction orthogonal to the first direction.

After the calibration is performed, as shown in FIG. 5, the dividing step is performed, and the cutting blade 22 of the cutting device cuts the bonded wafer 25 along the dividing line 13 and is divided into the surface of the component wafer 15A. Wafer.

In the embodiment shown in FIG. 5, the adhesive tape T is adhered to the wafer cover 20 of the bonded wafer 25, but the adhesive tape T may be attached to the back surface 11b of the wafer cover 11, and the dividing step may be performed.

In this case, since the wafer cover 20 is formed of transparent glass, it is possible to perform the effect and detect the planned dividing line 13 by photographing the bonded wafer 25 from the wafer cover 20 side by a general imaging element such as a CCD.

In the above embodiment, the cutting blade 22 is implemented. The step of dividing the bonded wafer 25 into wafers may be performed by forming a laser processing trench or a modified layer on the device wafer 11 and/or the wafer cover 20 by a laser processing device, by means of a braking device (Dividing device) The bonding wafer 25 is divided into individual wafers by using a laser processing groove or a modified layer as a starting point.

Next, a method of manufacturing a wafer according to a second embodiment of the present invention will be described with reference to Figs. 6 to 9 . In this embodiment, a wafer manufacturing method using Dicing Before Grinding is used.

In the layer removing step shown in FIG. 6(A), a plurality of laser processing grooves 16 are formed along the dividing line 13 and the width of the cutting blade is larger than the thickness of the cutting insert used in the cutting groove forming step of the next process. The Low-k film 13a which is a laminate is removed in the region.

However, it is also possible to increase the beam spot diameter of the irradiated laser beam, and remove the Low-k film 13a in the field of the width of the cutting blade or more by the irradiation of the laser beam once.

Alternatively, in the alternative embodiment, as shown in FIG. 6(B), a pair of laser processing grooves are formed along the dividing line 13 in a region where the front side of the cutting insert used in the cutting groove forming step of the next process is positioned. 16. The Low-k film 13a of the laminate is removed.

After the laminate removal step is carried out in this manner, as shown in FIG. 7(A), a cutting groove forming step is performed, along which the component wafer 11 is cut by the cutting insert 22A along the dividing line 13 of the component wafer 11, and the component wafer 11 is cut. A cutting groove 24 having a depth t1 to the processing thickness t1 of the element wafer 15A is formed. This cutting groove forming step is carried out for all the dividing line 13 to be divided.

As shown in FIG. 6(B), a pair of mines are formed along the dividing line 13 In the embodiment of the shot processing groove 16, as shown in Fig. 7(B), the cutting groove forming step is performed, and both the front and back surfaces of the cutting insert 22A are cut by the laser processing groove 16, whereby the mica is peeled off after cutting. The -k film 13a is cut at the laser processing groove 16 without adversely affecting the element 15.

After the cutting groove forming step is performed, the element wafer dividing step is performed, the back side of the element wafer 11 bonded to the wafer 25 is ground, the element wafer 11 is thinned to the processing thickness of the element wafer, and the cutting groove 24 is exposed. The element wafer 11 is divided into the respective element wafers 15A on the back surface of the element wafer 11.

In the element wafer dividing step, as shown in FIG. 8, the wafer cover 20 side of the bonding wafer 25 is sucked by the working chuck 30 of the grinding device, and the back surface 11b of the element wafer 11 is exposed.

Next, the work chuck 30 is rotated in a direction indicated by an arrow a at, for example, 300 rpm, and the grinding wheel 38 is rotated in a direction indicated by an arrow b at, for example, 6000 rpm, and the grinding unit transfer mechanism is driven to cause the grinding wheel 42 of the grinding wheel 38. It is in contact with the back surface 11b of the element wafer 11. Next, the grinding wheel 38 is conveyed downward by a predetermined amount by the predetermined grinding conveyance speed.

When the element wafer 11 is ground to a desired thickness t1, the cutting groove 24 is exposed on the back surface 11b of the element wafer 11, and the element wafer 11 is divided into individual element wafers 15A.

After the back surface 11b of the element wafer 11 is ground, and the element wafer 11 is divided by the respective element wafers 15A, the wafer cover dividing step of dividing the wafer cover 20 along the dividing line 13 is performed. Before the wafer cover dividing step is performed, the bonding wafer 25 is attached to the adhesive tape T as shown in FIG.

Next, the cutting blade 22 passes through the cutting groove 24 of the component wafer 11 The wafer cover 20 is cut, and a wafer to which the cap plate 23 is attached is formed on the surface of the element wafer 15A.

10‧‧‧ Laser processing equipment

11‧‧‧Component Wafer

11a‧‧‧ surface

12‧‧‧Working table

13‧‧‧Division line

14‧‧‧ concentrator

15‧‧‧ CMOS image sensing components

16‧‧‧Laser processing ditch

X1‧‧‧ arrow

Claims (1)

A method for manufacturing a covered wafer, comprising: a component wafer having a component on a surface thereof; and a cover plate disposed on a surface of the crystal face of the component, characterized by the following steps: component wafer preparation step Forming a component wafer of each of the regions defined by the plurality of intersecting dividing lines formed on the surface and interleaving; the layer removing step, irradiating the laser beam along the dividing line of the component wafer a laminate laminated on the dividing line; a bonding wafer forming step, after performing the layer removing step, causing the bonding member to be interposed between the components surrounding the component wafer and not between the components And bonding a wafer to the surface of the component wafer to form a bonding wafer; and the cutting groove forming step, after performing the layer removing step, the cutting blade along the predetermined dividing line of the component wafer Cutting the component wafer and forming a cutting groove having a depth to a processing thickness of the component wafer; and dividing the step, after performing the cutting groove forming step, along the dividing pre- The wire is divided into a plurality of capped wafers formed on the surface of the component wafer and provided with a cover plate, and the dividing step includes: a component wafer dividing step, and performing the bonding wafer forming step, grinding Forming the back side of the component wafer of the bonded wafer Thinning is performed on the processing thickness of the component wafer, and the cutting trench is exposed on the back surface of the component wafer to divide the component wafer into individual component wafers; and the wafer cover dividing step is along the dividing line The aforementioned wafer cover is divided.