Machining apparatus

Abstract

To provide a machining device capable of reducing an installation space by miniaturization and shortening a machining time.SOLUTION: The processing apparatus 1 includes a chuck table 10 for holding and rotating a wafer, a turn table (horizontal moving mechanism) 2 for moving the chuck table 10, a loading mechanism 85 and an unloading mechanism 90 for loading and unloading the wafer onto and from the chuck table 10, a recess forming mechanism 20 for grinding the wafer by a recess forming grindstone to form a circular recess in a central portion of the wafer W, a bottom surface grinding mechanism 30 for grinding a bottom surface of the circular recess formed in the wafer by a bottom surface grinding grindstone, a recess-forming-grindstone horizontal moving mechanism 26 for moving the recess forming grindstone in a horizontal direction, a bottom surface grinding grindstone horizontal moving mechanism 27 for moving the bottom surface grinding grindstone in a direction parallel to a holding surface, and an etching unit 60 for etching the circular recess by applying atmospheric pressure plasma to the circular recess of the wafer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a processing apparatus for grinding the central portion of one surface of a wafer to form a circular recess and an annular protrusion surrounding the circular recess. [Background technology]

[0002] In the manufacturing process of semiconductor devices such as ICs and LSIs used in electronic devices, the backside of a wafer is ground to thin the wafer to a predetermined thickness in order to reduce the size and weight of the semiconductor device. In particular, in recent years, there has been a demand for thinner semiconductor devices to meet the demand for thinner and more compact electronic devices. However, when a wafer is ground to a thickness of, for example, 50 μm or less, the flexural strength of the wafer decreases, making it more susceptible to breakage and making subsequent handling difficult.

[0003] Therefore, for example, Patent Document 1 proposes a grinding method in which only the backside of the wafer in the area where the device is formed is ground to form a circular recess in the center, and an annular protrusion of the same thickness as before grinding is left on the outer periphery of this circular recess as a reinforcing part, thereby increasing the rigidity of the wafer after grinding. Hereinafter, this type of grinding will be referred to as "TAIKO grinding." "TAIKO" is a registered trademark.

[0004] Patent Document 2 proposes a spin etching method in which an etching solution is supplied to a circular recess of a wafer that has an annular protrusion formed on its outer periphery as a reinforcing portion by TAIKO grinding, and the circular recess is etched with the etching solution to achieve a mirror finish. Patent Document 3 also proposes a method in which the circular recess of a wafer is polished with a polishing pad to achieve a mirror finish. By polishing the circular recess of the wafer to a mirror finish in this way, grinding marks that could be the starting point for cracks and other problems can be removed, and a thin metal film can be formed in the circular recess. Furthermore, because the boundary between the bottom of the circular recess and the inner surface of the annular protrusion is also polished, the strength of the wafer after TAIKO grinding can be increased, making the wafer easier to handle in the next process.

[0005] Incidentally, an insulating film such as an oxide film is formed on the surface of a wafer, but as described in Patent Document 4, the insulating film is removed when the wafer is subjected to TAIKO grinding. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-019461 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-188549 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-010557 [Patent Document 4] Japanese Patent Application Publication No. 2019-057526 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, wafer processing may require a grinding machine capable of TAIKO grinding, an etching machine that etches the wafer's surface to be ground after TAIKO grinding, an insulating film removal machine that removes the insulating film on the wafer's surface to be ground before TAIKO grinding, etc. If such grinding machines, etching machines, insulating film removal machines, etc. are installed independently, the space required to install these machines increases, making the entire processing machine larger, and there are problems with longer processing times due to the effort and time required to transport wafers between each machine.

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to provide a processing device that can be made compact to reduce the installation space and shorten the processing time. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides a processing apparatus for grinding a central portion of one side of a wafer to form a circular recess and an annular convex portion surrounding the circular recess on one side of the wafer, the processing apparatus comprising: a chuck table that holds and rotates a wafer on a holding surface; a horizontal movement mechanism that moves the chuck table in a direction parallel to the holding surface; a transport mechanism that loads and unloads wafers relative to the chuck table; a recess forming mechanism that grinds the wafer held on the chuck table with an annular recess forming grindstone to form the circular recess in the central portion of the wafer; a bottom surface grinding mechanism that grinds the bottom surface of the circular recess formed in the wafer held on the chuck table with an annular bottom surface grinding stone; a recess forming grindstone horizontal movement mechanism that moves the recess forming grindstone in a direction parallel to the holding surface; a bottom surface grinding stone horizontal movement mechanism that moves the bottom surface grinding stone in a direction parallel to the holding surface; and an etching unit that etches the circular recess of the wafer by irradiating atmospheric pressure plasma to the circular recess. [Effects of the Invention]

[0010] According to the present invention, a processing apparatus for obtaining wafers that are easy to handle, not easily broken, and in which a metal layer can be easily formed in a circular recess incorporates a recess forming mechanism that forms a circular recess in the center of the wafer, a bottom grinding mechanism that grinds the bottom of the circular recess formed in the wafer by the recess forming mechanism, and an etching unit that etches the circular recess in the wafer by irradiating atmospheric pressure plasma onto the circular recess.This has the effect of making the processing apparatus smaller and reducing the installation space, and shortening the processing time by allowing wafers to be transported between each mechanism in a short time. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view of a processing device according to the present invention. [Figure 2] FIG. 2 is an exploded perspective view of a wafer and a protective sheet. [Figure 3] FIG. 10 is a partial cross-sectional side view showing TAIKO grinding using a wafer recess forming mechanism. [Figure 4] FIG. 1 is a partial plan view showing TAIKO grinding by a wafer recess forming mechanism. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6] FIG. 10 is a partial cross-sectional side view showing grinding of the bottom surface of the circular recess by the wafer bottom surface grinding mechanism. [Figure 7] 10 is a partial cross-sectional side view showing grinding of an annular protrusion by a wafer protrusion grinding mechanism. FIG. [Figure 8] 3 is a cutaway side view of an etching unit provided in the processing apparatus according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0013] [Configuration of processing equipment] First, the configuration of the processing device according to the present invention will be described with reference to Fig. 1. In the following description, the arrow directions shown in Fig. 1 are the X-axis direction (left-right direction) and the Y-axis direction (front-rear direction), respectively.

[0014] The processing apparatus 1 shown in FIG. 1 is an apparatus that performs TAIKO grinding on the back surface (the lower surface in FIG. 2) of a thin, disk-shaped wafer W (see FIG. 2), cleans the ground wafer W, and then plasma etches the ground portion of the wafer W, and is equipped with a rectangular box-shaped base 100 that is long in the Y-axis direction.

[0015] In this processing apparatus 1, the base 100 is equipped with, as its main components, a rotatable, disk-shaped turntable 2 that constitutes a horizontal movement mechanism, four chuck tables 10 arranged on the turntable 2, a loading mechanism 85 that loads wafers W onto the chuck table 10 and a loading mechanism 90 that loads wafers W onto the chuck table 10, a recess forming mechanism 20 that forms circular recesses W1 (see Figure 5) in the wafers W held on the chuck table 10 by TAIKO grinding, a bottom grinding mechanism 30 that grinds the bottom surfaces of the circular recesses W1 of the wafers W, a convexity grinding mechanism 40 that grinds annular convexities W2 formed on the outer periphery of the wafers W by TAIKO grinding, a cleaning mechanism 50 that cleans the back surfaces (grinding surfaces) of the TAIKO-ground wafers W, and an etching unit 60 that plasma-etches the circular recesses W1 of the wafers W whose back surfaces have been cleaned.

[0016] In addition, the processing apparatus 1 is equipped with a pair of cassettes 81, 82 arranged side by side along the X-axis direction (left-right direction) at the -Y-axis direction end (lower end in Figure 1) of the base 100, a transfer robot 83 that transfers wafers W into and out of these cassettes 81, 82, and a positioning table 84 that positions the temporarily placed wafers W.

[0017] Here, as shown in Fig. 2, the wafer W, which is the workpiece, is a thin, disk-shaped member made of, for example, single-crystal silicon (Si). The surface of the wafer W (the top surface in Fig. 2) is partitioned into a plurality of rectangular regions by mutually orthogonal dividing lines L1, L2 arranged in a grid pattern, and each rectangular region has a device D, such as an IC or LSI, formed therein. Therefore, the surface of the wafer W has a circular device region S1 in which the device D is formed, and a ring-shaped peripheral excess region S2 formed around the device region S1. In addition, a thin, circular protective sheet T is attached to the surface of the wafer W to protect the device D. In addition to silicon (Si), the wafer W may be made of hard silicon carbide (SiC), glass, ceramics, sapphire, or the like.

[0018] Next, the configurations of the main components of the processing device 1, namely the turntable 2, chuck table 10, loading mechanism 85, unloading mechanism 90, recess forming mechanism 20, bottom grinding mechanism 30, convex grinding mechanism 40, cleaning mechanism 50 and etching unit 60, will be described.

[0019] (Turntable) The turntable 2 constitutes a horizontal movement mechanism that rotates intermittently by 90° increments around a vertical central axis in the direction of the arrows in the figure by a rotation mechanism (not shown), and moves four chuck tables 10 arranged on top of it horizontally successively to a wafer loading / unloading region R1, a recess formation region R2, a bottom grinding region R3, and a protrusion grinding region R4. Here, the upper surface of the turntable 2 is divided into four areas A1, A2, A3, and A4 by partition walls 3 that are cross-shaped in a plan view, and a chuck table 10 is arranged in each of the areas A1 to A4.

[0020] (Chuck table) The four chuck tables 10 arranged on the turntable 2 are disk-shaped members, and are arranged at equal angular pitches (90° pitches) in the circumferential direction on the respective areas A1 to A4 of the turntable 2, which rotates intermittently about a vertical central axis. These chuck tables 10 revolve around the vertical axis of the turntable 2 at 90° intervals as the turntable 2 intermittently rotates, and move sequentially among the wafer loading / unloading area R1, the recess formation area R2, the bottom grinding area R3, and the protrusion grinding area R4, and are also rotated (spinned) around the central axis at a predetermined speed by a table rotation mechanism (not shown).

[0021] 3, 6, and 7, each chuck table 10 rotates (spins) about the vertical axis at a predetermined speed in the direction of the arrow in the drawings, as a rotation axis 12 extending vertically downward from the center is rotationally driven by a table rotation mechanism (not shown). Here, a disk-shaped porous member 11 made of porous ceramic or the like is incorporated into a circular recess 10a formed in the upper part of a disk-shaped frame 10A of each chuck table 10, and the upper surface of each porous member 11 forms a holding surface that suction-holds the wafer W.

[0022] In addition, in each chuck table 10, the porous member 11 is selectively connected to a suction source 15 such as a vacuum pump or an ejector via a communicating passage 13 formed in the center of each of the frame body 10A and the rotating shaft 12 and a pipe 14 connected to the communicating passage 13.

[0023] (Loading mechanism) 1 is a mechanism for holding a wafer W positioned on a positioning table 84 and transporting it to a chuck table 10 located in a wafer loading / unloading area R1, as will be described later, and includes a horizontal support arm 87 that is movable in the Y-axis direction along a guide rail 86 that extends linearly in the Y-axis direction, and a disk-shaped suction pad 88 attached to the tip of the support arm 87. The suction pad 88 is selectively connected to a suction source (not shown). In addition, a camera 89 that captures an image of the top surface of the wafer W placed on the positioning table 84 is attached to the end of the guide rail 86 in the -Y-axis direction (the lower end in FIG. 1).

[0024] (Export mechanism) The unloading mechanism 90 is a mechanism that receives the wafer W that has been subjected to a series of processes as described below from the chuck table 10 located in the wafer loading / unloading area R1 and transports it to the cleaning mechanism 50, and includes a slider 92 that is movable in the Y-axis direction along a guide rail 91 that extends linearly in the Y-axis direction, a horizontal support arm 93 whose base end is swingably supported by the slider 92, and a disk-shaped suction pad 94 attached to the tip of the support arm 93. The suction pad 94 is selectively connected to a suction source (not shown).

[0025] (Recess formation mechanism) The recess forming mechanism 20 is a mechanism for forming a circular recess W1 (see FIG. 5) in the center of the back surface of the wafer W (the surface opposite to the surface on which the device D (see FIG. 2) is formed) by TAIKO grinding. As shown in FIG. 1, the recess forming mechanism 20 is disposed in a recess forming region R2 on a rectangular box-shaped base 100 elongated in the Y-axis direction. The recess forming mechanism 20 includes a spindle motor 22 fixed to a holder 21, a vertical spindle 23 (see FIG. 3) rotated by the spindle motor 22, a disk-shaped mount 24 attached to the lower end of the spindle 23, and a grinding wheel 25 (see FIG. 3) detachably attached to the lower surface of the mount 24. As shown in FIG. 3, the grinding wheel 25 is composed of a disk-shaped base 25a and a plurality of annular recess forming grinding wheels 25b, which are processing tools attached in a circular shape to the lower surface of the base 25a. The grinding wheel 25 is rotated at a predetermined speed in the direction of the arrow in the figure around the vertical axis of the spindle 23, which is the grinding wheel rotation axis.

[0026] 1, a block-shaped column 101 is erected vertically in recess formation region R2 on base 100, and between an inclined surface 101a of column 101, which forms an oblique angle of 45° in a plan view, and holder 21 of recess formation mechanism 20, there are provided a recess formation grindstone horizontal movement mechanism 26 that moves recess formation grindstone 25b horizontally along inclined surface 101a of column 101, and a recess formation grindstone vertical movement mechanism 27 that raises and lowers recess formation grindstone 25b in the up and down direction (the direction perpendicular to the plane of FIG. 1). Note that recess formation grindstone horizontal movement mechanism 26 and recess formation grindstone vertical movement mechanism 27 are configured by known ball screw mechanisms, and therefore detailed illustration and description of their configurations will be omitted.

[0027] Furthermore, a thickness measuring device 28 is provided in the recess formation region R2 on the base 100 to measure the thickness of the circular recess W1 (see FIG. 5) of the wafer W during TAIKO grinding. This thickness measuring device 28 is a height gauge and includes a first probe 28a that contacts the bottom surface of the circular recess W1 of the wafer W and a second probe 28b that contacts the top surface of the frame 10A of the chuck table 10 (see FIG. 3). The thickness of the circular recess W1 of the wafer W can be measured by subtracting the top surface height of the frame 10A of the chuck table 10 detected by the second probe 28b from the bottom surface height of the circular recess W1 of the wafer W detected by the first probe 28a.

[0028] (Bottom grinding mechanism) Bottom surface grinding mechanism 30 is a mechanism for grinding the bottom surface of circular recess W1 formed in the center of the back surface of wafer W by recess forming mechanism 20, and is arranged in bottom surface grinding region R3 on base 100 as shown in Fig. 1. The basic configuration of bottom surface grinding mechanism 30 is the same as that of recess forming mechanism 20. That is, bottom surface grinding mechanism 30 includes a holder 31, a spindle motor 32 fixed to holder 31, a vertical spindle 33 (see Fig. 6) rotated by spindle motor 32, a disk-shaped mount 34 attached to the lower end of spindle 33, and a grinding wheel 35 (see Fig. 6) detachably attached to the lower surface of mount 34. Here, as shown in Figure 6, the grinding wheel 35 is composed of a disk-shaped base 35a and a plurality of annular bottom grinding stones 35b, which are processing tools attached to the underside of the base 35a in a circular ring shape, and is driven to rotate at a predetermined speed in the direction of the arrow shown around the vertical axis center of the spindle 33, which is the grinding stone rotation axis.

[0029] 1, a block-shaped column 102 is set up vertically in the bottom surface grinding region R3 on the base 100, and between an inclined surface 102a of the column 102, which forms an angle of 45° in a plan view, and the holder 31 of the bottom surface grinding mechanism 30, there are provided a bottom surface grinding wheel horizontal movement mechanism 36 that moves the bottom surface grinding wheel 35b horizontally along the inclined surface 102a of the column 102, and a bottom surface grinding wheel vertical movement mechanism 37 that raises and lowers the bottom surface grinding wheel 35b in the vertical direction (the direction perpendicular to the plane of the paper in FIG. 1). Note that the bottom surface grinding wheel horizontal movement mechanism 36 and the bottom surface grinding wheel vertical movement mechanism 37 are configured using known ball screw mechanisms, and therefore detailed illustrations and explanations of their configurations will be omitted.

[0030] Furthermore, a thickness measuring device 38 is provided in the bottom surface grinding region R3 on the base 100 to measure the thickness of the circular recess W1 of the wafer W while the bottom surface of the circular recess W1 is being ground. This thickness measuring device 38 has a first probe 38a that contacts the bottom surface of the circular recess W1 of the wafer W and a second probe 38b that contacts the upper surface of the frame 10A (see FIG. 6) of the chuck table 10, and its operation is the same as that of the thickness measuring device 28, so a repeated description thereof will be omitted.

[0031] (Convex grinding mechanism) The protrusion grinding mechanism 40 is a mechanism for grinding annular protrusions W2 formed on the outer periphery of the back surface of the wafer W after the bottom surface of the circular recess W1 has been ground by the bottom surface grinding mechanism 30, or the outer periphery of the back surface of the wafer W before the circular recess W1 is formed (the portion where the annular protrusions W2 will be formed), and is disposed in a protrusion grinding region R4 on the base 100, as shown in FIG. 1. The basic configuration of this protrusion grinding mechanism 40 is the same as that of the recess forming mechanism 20 and the bottom surface grinding mechanism 30. That is, this protrusion grinding mechanism 40 includes a holder 41, a spindle motor 42 fixed to the holder 41, a vertical spindle 43 (see FIG. 7) rotated by the spindle motor 42, a disk-shaped mount 44 attached to the lower end of the spindle 43, and a grinding wheel 45 (see FIG. 7) detachably attached to the lower surface of the mount 44. Here, as shown in Figure 7, the grinding wheel 45 is composed of a disk-shaped base 45a and a plurality of annular convex grinding stones 45b, which are processing tools attached to the underside of the base 45a in a circular ring shape, and is driven to rotate at a predetermined speed in the direction of the arrow shown around the vertical axis center of the spindle 43, which is the grinding stone rotation axis.

[0032] As shown in FIG. 1 , a block-shaped column 103 is vertically installed in the convex portion grinding region R4 on the base 100. Between the inclined surface 103a of the column 103, which is at an angle of 45° in a plan view, and the holder 41 of the convex portion grinding mechanism 40, there are provided a convex portion grinding wheel horizontal movement mechanism 46 that moves the convex portion grinding wheel 45b horizontally along the inclined surface 103a of the column 103, and a convex portion grinding wheel vertical movement mechanism 47 that raises and lowers the convex portion grinding wheel 45b in the vertical direction (perpendicular to the plane of FIG. 1 ). Note that the convex portion grinding wheel horizontal movement mechanism 46 and the convex portion grinding wheel vertical movement mechanism 47 are configured using known ball screw mechanisms, and therefore detailed illustrations and descriptions of their configurations are omitted. Furthermore, a thickness measuring device 48 including a first probe 48a and a second probe 48b is provided in the convex portion grinding region R4 on the base 100.

[0033] (cleaning mechanism) The cleaning mechanism 50 shown in FIG. 1 is used to clean a wafer W having a circular recess W1 and an annular protrusion W2 formed on its back surface by TAIKO grinding, and to remove grinding debris and the like adhering to the back surface (surface to be ground). It is equipped with a spinner table 51 that holds the wafer W and rotates at high speed, and a cleaning water nozzle 52 that sprays cleaning water toward the center of the surface to be ground of the wafer W.

[0034] As shown in FIG. 8, the center of the spinner table 51 is attached to an output shaft (motor shaft) 53a extending vertically upward from a table motor 53, which is a rotary drive source disposed below the spinner table 51. The table motor 53 is equipped with an encoder 54 that detects the direction and speed of rotation. Therefore, when the table motor 53 is started and the output shaft 53a rotates, the spinner table 51 attached to the upper end of the output shaft 53a is driven to rotate at high speed around the center of the output shaft 53a. The cleaning water nozzle 52 is attached to the tip of a rotating arm 55 that rotates in a horizontal plane around its base end. A cleaning water supply source (not shown) is connected to the cleaning water nozzle 52. Pure water is preferably used as the cleaning water.

[0035] (etching unit) The etching unit 60 is a unit that etches a circular recess W1 formed in a wafer W whose back surface has been cleaned by the cleaning mechanism 50 by irradiating the circular recess W1 with atmospheric pressure plasma, and in this embodiment, is provided in the cleaning mechanism 50 as shown in Fig. 1. That is, as shown in Fig. 8, the etching unit 60 provided in the cleaning mechanism 50 includes a rotary arm 62 that can rotate horizontally around a vertical rotation shaft 61 at its base end, and an etching nozzle 63 that is attached vertically to the tip of the rotary arm 62. Here, the detailed configuration of the etching unit 60 will be described below with reference to Fig. 8.

[0036] 8, vertical rotation shaft 61 is connected to an output shaft (motor shaft) 64a extending vertically upward from a rotation motor 64, which is a rotation drive source located below, and the base end of a horizontal rotation arm 62 is attached at a right angle to the upper end of this rotation shaft 64a. An encoder 65 is attached to rotation motor 64 to detect its rotation direction and rotation speed.

[0037] An etching nozzle 63 attached vertically to the tip of the rotating arm 62 includes a cylindrical heating section 63A, a plasma generating section 63B, and a plasma output section 63C of different diameters, with the smaller diameter heating section 63A and plasma output section 63C being provided above and below the larger diameter plasma generating section 63B. A circular hole-shaped space 66 is formed in the center of the interior of the plasma generating section 63B, and a cylindrical coil 67 is disposed around this space 66. A high-frequency power supply 68 is electrically connected to the coil 67.

[0038] Furthermore, a circular hole-shaped gas passage 69 is formed vertically in the center of heating unit 63A and in the upper center of plasma generating unit 63B, and this gas passage 69 is connected to a space 66 formed inside plasma generating unit 63B. This gas passage 69 is connected to a halogen gas supply source 71 via a pipe 70.

[0039] Furthermore, a cylindrical heater electrode 72 is disposed around the gas passage 69 inside the heating part 63A, and a heater power supply 73 is electrically connected to this heater electrode 72. A small-diameter plasma passage 74 is formed vertically at the center of the lower part of the plasma generation part 63B and the axial center of the plasma output part 63C, and this plasma passage 74 opens as a circular hole-shaped irradiation port 74a on the lower surface of the plasma output part 63C.

[0040] A cylindrical suction path 75 is formed around the plasma passage 74 inside the plasma output part 63C, and this suction path 75 opens as a circular suction port 75a on the bottom surface of the plasma output part 73C. A suction source 78 is connected to this suction path 75 via a communication path 76 formed horizontally in the plasma output part 63C and a pipe 77 connected to the communication path 76.

[0041] [Processing equipment operation] Next, the operation of the processing device 1 configured as above will be described.

[0042] 1 is taken out by a carry-in / out robot 83 and carried to a positioning table 84. Then, at the positioning table 84, the upper surface of the wafer W is imaged by a camera 89, and the wafer W is positioned (centered) based on the image. The positioned wafer W is then sucked by a suction pad 88 of a carry-in mechanism 85 and carried to a chuck table 10 located in a wafer carry-in / out area R1, where it is placed on the holding surface of the chuck table 10 with the protective sheet T facing down.

[0043] As described above, when the wafer W is transported to the chuck table 10 located in the wafer loading / unloading area R1 and placed on the holding surface of the chuck table 10, the porous member 11 of the chuck table 10 is connected to the suction source 15, and a negative pressure is generated in the porous member 11. As a result, the wafer W is attracted by this negative pressure and held by suction on the holding surface of the chuck table 10 (see Figure 3).

[0044] Then, the turntable 2 shown in Figure 1 is rotated by an angle of 90° in the direction of the arrow in Figure 1 by a rotation mechanism not shown, the chuck table 10 holding the wafer W moves from the wafer loading / unloading area R1 to the recess formation area R2, the wafer W is TAIKO ground by the recess formation mechanism 20, a circular recess W1 is formed in the center (the part corresponding to the device area S1 on the front surface) of the back surface (the surface on which no device is formed as shown in Figure 2) of the wafer W, and an annular convex part W2 is formed around this circular recess W1 (the part corresponding to the peripheral excess area S2 on the front surface).

[0045] That is, when a circular recess W1 is formed in the center of the back surface of the wafer W by TAIKO grinding using the recess forming mechanism 20, the wafer W is positioned below the grinding wheel 25 of the recess forming mechanism 20. At this time, the grinding wheel 25 is moved horizontally in the radial direction of the wafer W by the recess forming grindstone horizontal movement mechanism 26, and both are positioned so that the circumscribed circle of the recess forming grindstone 25b passes through the center O of the wafer W, as shown in FIG.

[0046] From the above state, the chuck table 10 and the wafer W held thereon are rotated at a predetermined speed in the direction of the arrows in Figures 3 and 4 by a table rotation mechanism (not shown), and the spindle motor 22 of the recess forming mechanism 20 shown in Figure 1 is started to rotate the recess forming grindstone 25b of the grinding wheel 25 at a predetermined speed in the direction of the arrows in Figures 3 and 4. In this state, the grinding wheel 25 is lowered at a predetermined speed by the recess forming grindstone vertical movement mechanism 27 shown in Figure 1. Then, the rotating recess forming grindstone 25b of the recess forming mechanism 20 continuously contacts the center O of the wafer W rotating together with the chuck table 10, and the back surface (upper surface in Figure 3) of the wafer W is ground by the recess forming grindstone 25b, and a circular recess W1 is formed in the center of the back surface of the wafer W, as shown in Figures 4 and 5.

[0047] As described above, while the back surface of the wafer W is being TAIKO-ground by the recess-forming grindstone 25b, the thickness of the circular recess W1 formed in the center of the back surface of the wafer W is measured by the thickness gauge 28, and TAIKO grinding of the wafer W by the recess-forming grindstone 25b is continued until the circular recess W1 of the wafer W reaches a predetermined thickness. During TAIKO grinding of the wafer W by the recess-forming grindstone 25b, grinding water is supplied from a grinding water supply source (not shown) to the contact area (grinding area) between the recess-forming grindstone 25b and the wafer W. This grinding water cools the contact area (grinding area) between the recess-forming grindstone 25b and the wafer W, and also washes away and removes grinding debris generated by grinding. Pure water is preferably used as the grinding water.

[0048] Thus, a circular recess W1 of a predetermined thickness is formed in the center of the back surface of the wafer W by TAIKO grinding of the wafer W with the recess-forming grindstone 25b, and a ring-shaped protrusion W2 is formed around the circular recess W1. Then, the recess-forming grindstone vertical movement mechanism 27 moves the recess-forming grindstone 25b away from the wafer W. From this state, the turntable 2 shown in FIG. 1 is rotated by an angle of 90° in the direction of the arrow by a rotation mechanism (not shown), and the chuck table 10 and the wafer W held on the holding surface of the chuck table 10 move from the recess-forming region R2 to the bottom surface grinding region R3. When the chuck table 10 and the wafer W held thereon move to the bottom surface grinding region R3 in this manner, the circular recess W1 of the wafer W is ground by the bottom surface grinding mechanism 30, as shown in FIG. 6.

[0049] That is, the chuck table 10 and the wafer W held thereon are rotated at a predetermined speed in the direction of the arrow in Fig. 6 by a table rotation mechanism (not shown), and the spindle motor 32 of the bottom surface grinding mechanism 30 shown in Fig. 1 is started to rotate the bottom surface grinding wheel 35b of the grinding wheel 35 at a predetermined speed in the direction of the arrow in Fig. 6. Then, the bottom surface grinding wheel 35b is lowered at a predetermined speed by the bottom surface grinding wheel vertical movement mechanism 37 shown in Fig. 1. Then, the rotating bottom surface grinding wheel 35b of the bottom surface grinding mechanism 30 continuously contacts the center O of the wafer W rotating together with the chuck table 10, and the bottom surface of the circular recess W1 formed in the center of the back surface of the wafer W is ground by the bottom surface grinding wheel 35b. Grinding marks that were generated on the bottom surface of the circular recess W1 of the wafer W by grinding with the recess forming grinding wheel 25b in the previous process are removed, preventing cracks in the wafer W originating from the grinding marks.

[0050] As described above, while the bottom surface of the circular recess W1 of the wafer W is being ground by the bottom surface grinding wheel 35b, the thickness of the circular recess W1 is measured by the thickness measuring device 38, and grinding of the circular recess W1 of the wafer W by the bottom surface grinding wheel 35b is continued until the thickness of the circular recess W1 reaches a predetermined thickness. During grinding of the bottom surface of the circular recess W1, grinding water is supplied from a grinding water supply source (not shown) to the contact portion (grinding portion) between the bottom surface grinding wheel 35b and the wafer W, and this grinding water cools the contact portion (grinding portion) between the bottom surface grinding wheel 35b and the wafer W, and grinding chips generated by grinding are washed away and removed by the grinding water.

[0051] When the circular recess W1 formed in the center of the back surface of the wafer W is ground to a predetermined thickness by bottom grinding with the bottom grinding wheel 35b, the bottom grinding wheel vertical movement mechanism 37 moves the bottom grinding wheel 35b away from the wafer W. From this state, the turntable 2 shown in FIG. 1 is rotated by an angle of 90° in the direction of the arrow by a rotation mechanism (not shown), and the chuck table 10 and the wafer W held on the holding surface of the chuck table 10 move from the bottom grinding region R3 to the protrusion grinding region R4. When the chuck table 10 and the wafer W held thereon move to the protrusion grinding region R4 in this manner, the annular protrusion W2 of the wafer W is ground by the protrusion grinding mechanism 40, as shown in FIG. 7.

[0052] That is, the chuck table 10 and the wafer W held thereon are rotated at a predetermined speed in the direction of the arrow in Fig. 7 by a table rotation mechanism not shown, and the spindle motor 42 of the protrusion grinding mechanism 40 shown in Fig. 1 is started to rotate the protrusion grinding stone 45b of the grinding wheel 45 at a predetermined speed in the direction of the arrow in Fig. 7, and in this state, the protrusion grinding stone 45b is lowered at a predetermined speed by the protrusion grinding stone vertical movement mechanism 47 shown in Fig. 1. Then, the rotating protrusion grinding stone 45b of the protrusion grinding mechanism 40 comes into contact with the annular protrusion W2 of the wafer W rotating together with the chuck table 10, and the annular protrusion W2 is ground by the protrusion grinding stone 45b.

[0053] During grinding of the annular convex portion W2 of the wafer W, grinding water is supplied to the contact portion (grinding portion) between the convex portion grinding wheel 45b and the wafer W from a grinding water supply source (not shown), and this grinding water cools the contact portion (grinding portion) between the convex portion grinding wheel 45b and the wafer W, and grinding chips generated by grinding are washed away and removed by the grinding water.

[0054] Thus, when the annular convex portion W2 of the wafer W is ground by the convex portion grinding wheel 45b, the convex portion grinding wheel 45b is separated from the wafer W by the convex portion grinding wheel vertical movement mechanism 47. From this state, the turntable 2 shown in Fig. 1 is rotated by an angle of 90° in the direction of the arrow by a rotation mechanism (not shown), and the chuck table 10 and the wafer W held on the holding surface of the chuck table 10 move from the convex portion grinding region R4 to the wafer transfer region R1. When the chuck table 10 and the wafer W held thereon move to the wafer transfer region R1 in this manner, the wafer W is suction-held by the suction pad 94 of the transfer mechanism 90 shown in Fig. 1 and transported to the cleaning mechanism 50.

[0055] In the cleaning mechanism 50, the wafer W is held by suction on the spinner table 51, and the spinner table 51 and the wafer W held thereon rotate at high speed, while the rotary arm 55 rotates horizontally about its base end, and the cleaning water nozzle 52 attached to the tip of the rotary arm 55 moves to above the center of the wafer W, and cleaning water (pure water) is sprayed from the cleaning water nozzle 52 toward the center of the wafer W. Then, the cleaning water sprayed from the cleaning water nozzle 52 toward the center of the wafer W is scattered radially outward from the wafer W by the centrifugal force caused by the rotation of the wafer W, and foreign matter such as grinding debris adhering to the surface of the wafer W is blown off and removed by the cleaning water, thereby cleaning the upper surface of the wafer W.

[0056] As described above, when the back surface (surface to be ground) of the wafer W is cleaned in the cleaning mechanism 50, the etching unit 60 provided in the cleaning mechanism 50 plasma-etches the circular recess W1 formed in the center of the back surface of the wafer W. That is, when the swing motor 64 shown in Fig. 8 is started, the swing arm 62 horizontally swings about the rotation axis 61 above the wafer W, and the etching nozzle 63 attached to the tip of the swing arm 62 moves above the center of the wafer W as shown in Figs. 1 and 8, atmospheric pressure plasma is irradiated from the etching nozzle 63 toward the circular recess W1 formed in the center of the back surface of the wafer W, and the circular recess W1 is plasma-etched.

[0057] 8, a heater power supply 73 energizes a heater electrode 72 to heat the heater electrode 72, and a high-frequency power supply 68 applies high-frequency power to a coil 67. A fluorine-based halogen gas, such as CF4, is supplied from a halogen gas supply source 71 through a pipe 70 to a gas passage 69 of the etching nozzle 63. The halogen gas flowing through the gas passage 69 is then heated to a predetermined temperature by the heater electrode 72 provided in the heating section 63A of the etching nozzle 63. The heated halogen gas is excited into plasma by a high-frequency current flowing through the coil 67 in a space 66 formed in a plasma generating section 63B of the etching nozzle 63, and atmospheric pressure plasma is generated in the space 66.

[0058] The atmospheric pressure plasma is then emitted from the space 66 of the etching nozzle 63 through the plasma passage 74 and the irradiation port 74a toward the circular recess W1 of the wafer W. The etching nozzle 63 is moved radially around the circular recess W1 while the wafer W is rotated about its center. The atmospheric pressure plasma emitted from the irradiation port 74a plasma-etches the entire surface of the circular recess W1 of the wafer W. The atmospheric pressure plasma used to etch the circular recess W1 of the wafer W passes through the suction port 75a, the suction path 75, the connecting passage 76, and the piping 77 and is then sucked by the suction source 78. By plasma-etching the entire surface of the circular recess W1 of the wafer W in this way, when a metal film or the like is formed on the surface of the circular recess W1 in the next process, the metal film can be made thinner. Furthermore, damage such as chipping occurring at the boundary Wa (see FIG. 8 ) between the bottom surface of the circular recess W1 of the wafer W and the inner circumferential surface of the annular protrusion W2 can be removed, thereby preventing cracks or the like from occurring at the boundary Wa of the wafer W.

[0059] Alternatively, the time for irradiating the atmospheric pressure plasma may be controlled to etch a large area. For example, atmospheric pressure plasma may be irradiated only to the corners between the bottom and inner side surfaces of the circular recess W1 of the wafer W to etch the corners and increase the die strength. Furthermore, the radial movement speed of the etching nozzle 63 and the rotation speed of the spinner table 51 may be controlled to control the amount of etching of the bottom surface of the circular recess W1, thereby making the thickness of the bottom surface of the circular recess W1 uniform through etching.

[0060] As described above, once the circular recesses of the wafer have been plasma etched, the wafer W is transported from the spinner table 51 to the cassette 82 by the transport robot 83 shown in FIG. 1 and stored in the cassette 82, completing the series of processing steps for the wafer W.

[0061] As described above, in this embodiment, the processing apparatus 1 for obtaining a wafer W that is easy to handle, not easily broken, and in which a metal layer can be easily formed in the circular recess W1 incorporates a recess forming mechanism 20 that forms the circular recess W1 in the center of the wafer W, a bottom grinding mechanism 30 that grinds the bottom of the circular recess W1 formed in the wafer W by the recess forming mechanism 20, a convex grinding mechanism 40 that grinds the annular convex portion W2 of the wafer W, and an etching unit 60 that etches the circular recess W1 of the wafer W by irradiating atmospheric pressure plasma to the circular recess W1.As a result, the processing apparatus 1 can be made smaller and its installation space can be kept small, and the wafer W can be transported between each mechanism in a short time, thereby shortening the processing time.

[0062] In the above embodiment, the processing apparatus 1 is provided with a convex portion grinding mechanism 40 for grinding the annular convex portion of the wafer, but this convex portion grinding mechanism 40 may be provided as needed and is not an essential component of the present invention.

[0063] Furthermore, the present invention is not limited to the application of the above-described embodiments, and it goes without saying that various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0064] 1: Processing equipment, 2: Turntable, 3: Partition wall, lifting mechanism, 10: chuck table, 10A: frame body, 10a: circular recess of frame body, 11 porous member, 12: Rotating shaft, 13: Connecting passage, 14: Pipe, 15: Suction source, 20: Recess forming mechanism, 21: holder, 22: spindle motor, 23: spindle, 24: mount, 25: grinding wheel, 25a: base, 25b: recess forming grindstone, 26: Horizontal movement mechanism for recessed portion forming grindstone, 27: Vertical movement mechanism for recessed portion forming grindstone, 28: Thickness measuring device, 28a: first probe, 28b: second probe, 30: bottom surface grinding mechanism, 31: holder, 32: spindle motor, 33: spindle, 34: mount, 35: grinding wheel, 35a: base, 35b: bottom grinding wheel, 36: bottom grinding wheel horizontal movement mechanism, 37: bottom grinding wheel vertical movement mechanism, 38: thickness measuring device, 38a: first probe, 38b: second probe, 40: convex portion grinding mechanism, 41: holder, 42: spindle motor, 43: spindle, 44: mount, 45: grinding wheel, 45a: base, 46: Convex grinding wheel horizontal movement mechanism, 47: Convex grinding wheel vertical movement mechanism, 48: Thickness measuring device, 48a: first probe, 48b: second probe, 50: cleaning mechanism, 51: spinner table, 52: cleaning water nozzle, 53: table motor, 53a: output shaft, 54: Encoder, 55: Swivel arm, 60: Etching unit, 61: Rotating shaft, 62: Swivel arm, 63: Etching nozzle, 63A: Heating unit, 63B: Plasma generating unit, 63C: plasma emission part, 64: rotation motor, 64a: output shaft, 65: encoder, 66: Space, 67: Coil, 68: High frequency power source, 69: Gas passage, 70: Pipe, 71: halogen gas supply source, 72: heater electrode, 73: heater power supply, 74: plasma passage, 74a: Irradiation port, 75: Suction path, 76: Communication path, 77: Piping: 78: Suction source, 81, 82: cassette, 83: loading / unloading robot, 84: positioning table, 85: Loading mechanism, 86: Guide rail, 87: Support arm, 88: Suction pad, 89: camera, 90: ejection mechanism, 91: guide rail, 92: slider, 93: Support arm, 94: Suction pad, 100: Base, A1 to A4: Area, D: device, L1, L2: planned dividing lines, O: center of wafer, R1: wafer loading / unloading area, R2: recess formation area, R3: bottom grinding area, R4: convex grinding area, S1: device area, S2: peripheral excess area, T: protective sheet, W: wafer, W1: circular recess of wafer, W2: annular protrusion of wafer, Wa: The boundary between the bottom surface of the circular recess and the inner surface of the annular protrusion of the wafer

Claims

1. A processing device for grinding a central portion of one surface of a wafer to form a circular recess and an annular protrusion surrounding the circular recess on the one surface of the wafer, a chuck table that holds and rotates the wafer on a holding surface; a horizontal movement mechanism that moves the chuck table in a direction parallel to the holding surface; a transfer mechanism for transferring a wafer onto or out of the chuck table; a recess forming mechanism that grinds the wafer held on the chuck table with an annular recess forming grindstone to form the circular recess in the center of the wafer; a bottom surface grinding mechanism that grinds the bottom surface of the circular recess formed in the wafer held on the chuck table with an annular bottom surface grinding wheel; a recess-forming grindstone horizontal movement mechanism that moves the recess-forming grindstone in a direction parallel to the holding surface; a bottom surface grinding wheel horizontal movement mechanism that moves the bottom surface grinding wheel in a direction parallel to the holding surface; an etching unit that etches the circular recess of the wafer by irradiating the circular recess with atmospheric pressure plasma; A processing device comprising:

2. 2. The processing apparatus according to claim 1, further comprising a convexity grinding mechanism for grinding at least the portion of one surface of the wafer held on the chuck table that will become the annular convexity with an annular convexity grinding wheel.

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