This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-040511, filed Mar. 12, 2021, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device.
There is disclosed a method of electrically connecting semiconductor elements to each other by forming a semiconductor element on each of a plurality of semiconductor wafers and bonding the semiconductor wafers to each other. Before or after bonding the semiconductor wafers to each other, a step of cutting (trimming) edge portions of the semiconductor wafers is performed.
However, due to the effect of unevenness of a surface of the semiconductor wafer, a load locally concentrates on the semiconductor wafer such that the edge of the semiconductor wafer may crack or chip during cutting.
Embodiments provide a semiconductor manufacturing apparatus that reduces cracking or chipping of a semiconductor wafer during cutting of an edge portion of the semiconductor wafer and a method of manufacturing a semiconductor device.
In general, according to at least one embodiment, provided is a semiconductor manufacturing apparatus including a stage configured to mount a wafer on a mounting surface. A blade is configured to cut an outer circumference portion of the wafer toward the mounting surface. The stage includes a protrusion portion provided at a position corresponding to a first region where a material film is not formed on a first surface of the outer circumference portion of the wafer facing the mounting surface.
Hereinafter, embodiments will be described with reference to the drawings. The embodiments do not limit the present disclosure. The drawings are schematic or conceptual, in which a ratio between components, and the like are not necessarily the same as the actual ones. In the specification and the drawings, the same components as described above with reference to the previous drawings are represented by the same reference numerals, and the detailed description thereof will not be repeated.
The cutting apparatus 1 as the semiconductor manufacturing apparatus includes a stage 10, a cutting unit 20, a control unit 60 (controller), a stage driving unit 45 (driver), and an imaging unit 50. A direction (vertical direction) substantially perpendicular to a mounting surface F1 of the stage 10 is a Z direction. An X direction and a Y direction are perpendicular to each other in a surface (horizontal surface) perpendicular to the Z direction.
The stage 10 is, for example, a table where the mounting surface F1 has a substantially flat disk shape, and a vacuum chuck is provided on the mounting surface F1. The stage 10 adsorbs a wafer 12 placed on the mounting surface F1 in a vacuum to stably hold the wafer 12. The stage 10 is configured to be rotatable in the horizontal surface (X-Y surface) around a rotation axis 10a that passes through the center of the stage 10 and extends in the vertical direction.
The wafer 12 is a semiconductor substrate such as a silicon substrate having a substantially disk shape and may be a single wafer 12 or may be a bonded wafer in which a plurality of wafers 12_1 and 12_2 are bonded as illustrated in
The cutting unit 20 includes: a cutting blade 22 mounted on a tip portion of a spindle 24; and a blade driving unit 25 that rotates a cutting blade 22 through the spindle 24. The cutting blade 22 is, for example, a very thin ring-shaped cutting grindstone that is formed by bonding a bonding material to an abrasive grain such as diamond. The blade driving unit 25 rotates the cutting blade 22 at a high speed around an axis 24a thereof through the spindle 24, and the cutting blade 22 that is rotating at a high speed is brought into contact with the wafer 12. As a result, the wafer 12 is cut, and a kerf is formed. The cutting unit 20 according to the embodiment executes a trimming process of cutting a part of an outer circumference portion 12c of the wafer 12 in a circumferential direction to remove a chamfered portion. Here, as the cutting blade 22, a thicker blade than that when a linear cutting line (street) between typical semiconductor elements is cut is used.
The cutting unit 20 further includes a cutting unit movement mechanism (not illustrated) and can move in the X, Y, and Z directions. For example, the X direction is a cutting direction. The Y direction is a horizontal direction perpendicular to the cutting direction (X-axis direction) and is an axial direction of the spindle 24 (extending direction of the spindle 24). The Z direction is a cutting depth direction (substantial perpendicular direction). The cutting unit 20 moves in the Y-axis direction such that an edge of the cutting blade 22 can be aligned with a cutting position (cutting line or outer circumference portion) of the wafer 12. The cutting unit 20 moves in the Z-axis direction such that the cutting depth of the cutting blade 22 relative to the wafer 12 can be adjusted.
During cutting, the stage driving unit 45 can rotate the stage 10 around the rotation axis 10a in the horizontal surface. As a result, the wafer 12 held on the stage 10 also rotates around the rotation axis 10a.
The imaging unit 50 (imager) includes an imaging element such as a CCD. The imaging unit 50 is disposed above the outer circumference portion 12c of the wafer 12 and images the wafer 12. The imaging unit 50 images a region including the cutting portion (that is, the outer circumference portion 12c) of the wafer 12 and outputs the obtained image to the control unit 60. As a result, the control unit 60 can specify the direction of the wafer 12 (the position in the circumferential direction) based on the position of the notch NT in
The control unit 60 controls the respective units of the cutting apparatus 1, for example, the stage 10, the cutting unit 20, and the stage driving unit 45. The control unit 60 functions as an image processing unit that processes the image obtained by the imaging unit 50 for the purposes of the alignment of the wafer 12, the check of the cutting state (chipping) after cutting, and the like.
The cutting apparatus 1 having the above-described configuration may cut one wafer 12. However, recently, in order to reduce the chip size or the package size, the cutting apparatus 1 may also cut the bonded wafer in which a plurality of wafers 12 are joined (bonded).
The cutting apparatus 1 cuts a part of the outer circumference portion 12c of the wafer 12 in the circumferential direction while rotating the stage 10. The cutting apparatus 1 cuts the outer circumference portion 12c in the substantially perpendicular direction from a front surface of the wafer 12 toward the mounting surface F1 to remove at least a part of a R shape of the outer circumference portion 12c (trimming). As a result, subsequently, if a back surface of the wafer 12 is ground by a grinder or the like until the thickness of the wafer 12 is less than the cutting depth, an edge angle of the outer circumference portion 12c of the wafer 12 (angle of a side surface with respect to the front surface and the back surface of the wafer 12) is substantially 90 degrees and is not an acute angle shape. As a result, the cracking and chipping of the outer circumference portion 12c of the wafer 12 can be reduced.
On the other hand, in a film forming step of forming a material film on the front surface or the back surface of the wafer 12, in order to hold the wafer 12 on the stage of the film forming apparatus, a holding tool (not illustrated) may come into partial contact with the outer circumference portion 12c of the wafer 12. In the portion of the front surface or the back surface of the wafer 12 in contact with the holding tool, the material film is not formed, and a contact trace of the holding tool remains.
As illustrated in
The material film TFc may be a material film that is formed on the back surface of the wafer 12_2 when a material film TFb is formed on the wafer 12_2. Accordingly, the material film TFc is a film that is removed in a subsequent backgrinding step of the wafer 12_2. For example, the wafers 12_1 and 12_2 include semiconductor elements on surfaces facing each other, and when the wafers 12_1 and 12_2 are bonded to each other, the semiconductor elements or wirings thereof are electrically connected to each other. When at least one embodiment is applied to a semiconductor memory, for example, a memory cell array (not illustrated) is formed on a bonding surface of the wafer 12_1, and a complementally metal-oxide-semiconductor (CMOS) circuit (not illustrated) that controls the memory cell array is formed on a bonding surface of the wafer 12_2. Here, a material film TFa may be an interlayer insulating film or a passivation film that covers the memory cell array of the wafer 12_1, and a part of the wiring connected to the memory cell array is exposed from the material film TFa. The material film TFb may be an interlayer insulating film or a passivation film that covers the CMOS circuit of the wafer 12_2, and a part of the wiring connected to the CMOS circuit is exposed from the material film TFb. By bonding the wafers 12_1 and 12_2 to each other, the memory cell array of the wafer 12_1 and the CMOS circuit of the wafer 12_2 are electrically connected to each other via the wiring. While cutting a part of the outer circumference portion 12c of the bonded wafer 12 in a trimming step such that the memory cell array remains on the CMOS circuit, the wafer 12_1 is thinned by backgrinding or the like. As a result, a semiconductor memory in which the memory cell array is provided on the CMOS circuit as a controller is formed. Therefore, the material film TFc may be removed by backgrinding or the like.
As illustrated in
The cutting apparatus 1 according to the embodiment cuts a part of the outer circumference portion 12c of the bonded wafer 12 (a portion above the outer circumference portion 12c of the wafer 12_1 and the outer circumference portion 12c of the wafer 12_2) placed on the stage 10 using the cutting blade 22. In at least one embodiment, the bonded wafer 12 is placed such that the front surface of the wafer 12_1 to be thinned in the subsequent backgrinding step faces upward (+Z direction). In a region of the stage 10 corresponding to the contact trace CT of the wafer 12_2, a space is formed between the surface of the stage 10 and the outer circumference portion 12c of the wafer 12. In the space, a pad 70 is provided.
The pad 70 is provided between the contact trace CT of the wafer 12_2 and the stage 10. The pad 70 is disposed opposite to the blade 22 with respect to the outer circumference portion 12c of the wafer 12_2 and is provided directly under the contact trace CT of the outer circumference portion 12c. As a result, the pad 70 functions as a spacer that embeds the space of the contact trace CT between the stage 10 and the outer circumference portion 12c, and functions as a support unit that supports the outer circumference portion 12c in the contact trace CT. It is preferable that the pad 70 has a lower elastic modulus than the wafer 12_2 or the material film TFc such that the bonded wafer 12 or the material film TFc is not damaged. Typically, the stage 10 is formed of a material having a high elastic modulus in order to reliably support the bonded wafer 12 while securing flatness during trimming. As the stage 10, for example, a material such as ceramic, stone, or metal is used. On the other hand, it is preferable that the pad 70 has a lower elastic modulus than the stage 10 such that the wafer 12_2 or the material film TFc in contact with the pad 70 is not damaged. As the pad 70, for example, a material such as resin is used.
Referring back to
On the other hand, the cutting apparatus 1 according to at least one embodiment illustrated in
As illustrated in
It is preferable that the height of the protrusion portion P70 is substantially the same or slightly higher than a gap in the Z direction between the mounting surface F1 and the contact trace CT of the wafer 12. An appropriate height of the protrusion portion P70 depends on the elastic modulus of the pad 70. Originally, the pad 70 is less than the gap between the mounting surface F1 and the contact trace CT of the wafer 12, and may have a function of compensating for the flatness of the wafer 12 by being expanded by heat or light after the mounting of the wafer 12.
Next, as illustrated in
A memory cell array MCA is provided above the CMOS circuit 31. The memory cell array MCA includes a plurality of memory cells at positions corresponding to intersections between word lines WL and semiconductor columns CL connected to bit lines BL. The memory cells are three-dimensionally arranged. The material film (interlayer insulating film) TFa covers the memory cell array MCA. A wiring 41 electrically connected to the memory cell array MCA is exposed from the material film TFa in the bonding surface S. The material films TFa and TFb are bonded to each other in the bonding surface S, and the wirings 38 and 41 are connected to each other in the bonding surface S.
The embodiment can be applied to the trimming step of the bonded wafer 12 of the semiconductor memories bonded as described above.
The embodiment can be applied not only to the contact trace CT of the support tool in the film forming step but also to unnecessary etching of the back surface of the wafer 12_2 occurring in a reactive ion etching (RIE) method.
In the first embodiment, the pad 70 is formed separately from the stage 10 and is fixed to the step portion ST of the Stage 10.
On the other hand, in the modification example, the pad 70 is integrated with the stage 10. Here, the pad 70 is formed of the same material as that of the stage 10 and is continuous as apart of the stage 10. The protrusion portion P70 protrudes from the mounting surface F1 as a part of the stage 10. Therefore, the stage 10 according to the modification example includes the protrusion portion P70 that is provided at the position corresponding to the contact trace CT of the wafer 12.
Even with such configuration, the effects of the first embodiment can be obtained. In the modification example, the pad 70 does not need to be formed in addition to the stage 10. Therefore, the steps of forming the stage 10 and the protrusion portion P70 can be simplified and reduced in time.
In the stage 10 of the cutting apparatus 1 according to the second embodiment, the pad 70 is provided over the entirety of the outer circumference portion of the stage 10. That is, the pad 70 is provided at all the positions on the mounting surface F1 of the stage 10 corresponding to the outer circumference portion 12c of the wafer 12_2. As a result, even when the positions or number of the contact traces CT in the outer circumference portion 12c of the wafer 12_2 is changed, the pad 70 can correspond to any number of contact traces CT at any positions of the outer circumference portion 12c. As a result, the cutting apparatus 1 according to the second embodiment can trim the wafer 12 formed by various kinds of film forming apparatuses while reducing the cracking or chipping of the wafer 12.
The above-described modification example may be applied to the second embodiment. That is, the protrusion portion P70 illustrated in
The pad 70 includes a plurality of divided regions 70a, 70b, 70c, and is provided over the entire outer circumference of the stage 10. Each of the regions 70a, 70b, 70c, . . . (hereinafter, referred to as the regions 70a and the like) is driven by the protrusion mechanism 80 to selectively protrude. For example, the pad 70 is formed of a flexible material such as resin, and each of the regions 70a and the like is formed of an air-tightly divided hollow bag. By introducing gas into the regions 70a and the like, the regions 70a and the like selectively expand and protrude from the mounting surface F1 of the stage 10. For example, in
The protrusion mechanism 80 includes: a pump that feeds gas to any one of the regions 70a and the like; and a pipe 81 that connects the pump and the regions 70a and the like to each other. The protrusion mechanism 80 introduces gas into any one of the regions 70a and the like at a position corresponding to the position coordinates of the contact trace CT to protrude. As a result, even when the positions or number of the contact traces CT in the outer circumference portion 12c of the wafer 12_2 is changed, the protrusion mechanism 80 can drive the regions 70a and the like corresponding to any number of contact traces CT at any positions of the outer circumference portion 12c to protrude. As a result, the cutting apparatus 1 according to the third embodiment can trim the wafer 12_2 formed by various kinds of film forming apparatuses while reducing the cracking or chipping of the wafer 12_2.
The protrusion mechanism 80 drives the pad 70 to protrude using an atmospheric pressure but may drive the pad 70 to protrude using another mechanism. For example, a piezoelectric element may be used for the pad 70. Here, the protrusion mechanism 80 selectively supplies electrical power to the piezoelectric element provided in each of the regions 70a and the like such that any one of the regions 70a and the like selectively protrudes. Even with such configuration, the effects of the third embodiment can be obtained.
While certain embodiments have been described these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel embodiments described herein may be embodied in a variety of other forms: furthermore various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such embodiments or modifications as would fall within the scope and spirit of the disclosure.
Number | Date | Country | Kind |
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2021-040511 | Mar 2021 | JP | national |