Method for manufacturing a semiconductor device and a semiconductor device.

Abstract

The present invention provides a method for manufacturing a semiconductor device and a semiconductor device that can suppress the bending of a semiconductor wafer in a specific direction. [Solution] The semiconductor device manufacturing method according to the embodiment involves forming a plurality of semiconductor elements in the device region of the first main surface of a semiconductor wafer, and when the first amount of warpage in the X-axis direction of the semiconductor wafer is smaller than the second amount of warpage in the Y-axis direction of the semiconductor wafer, a rim portion is formed on the semiconductor wafer that surrounds the plurality of semiconductor elements and has a rigidity in the Y-axis direction that is higher than the rigidity in the X-axis direction.

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for manufacturing a semiconductor device and a semiconductor device.

Background Art

[0002] As so-called power semiconductors, semiconductor elements such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) are known. Such semiconductor elements are manufactured, for example, through the following steps.

[0003] Perform various processes such as photolithography, ion implantation, and etching to form a plurality of semiconductor elements on the front surface side of the semiconductor wafer. Thereafter, the back surface of the semiconductor wafer is ground and thinned by back grinding or the like. Thereafter, for the back surface of the semiconductor wafer, formation of a metal film (electrode) by sputtering or the like is performed. Finally, a dicing process is performed to obtain a plurality of semiconductor chips including the semiconductor elements.

[0004] Thus, various processes are performed in units of semiconductor wafers up to the dicing process. However, due to the surface structure of the semiconductor elements formed on the semiconductor wafer, the semiconductor wafer may warp in a specific direction. In such a case, the difficulty of process flow increases.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0006] The problem that this invention aims to solve is to provide a method for manufacturing a semiconductor device and a semiconductor device that can suppress the bending of a semiconductor wafer in a specific direction. [Means for solving the problem]

[0007] In the semiconductor device manufacturing method according to the embodiment, a plurality of semiconductor elements are formed in the device region of the first main surface of a semiconductor wafer, and when the first amount of warpage in the X-axis direction of the semiconductor wafer is smaller than the second amount of warpage in the Y-axis direction of the semiconductor wafer, a rim portion is formed on the semiconductor wafer that surrounds the plurality of semiconductor elements and has a rigidity in the Y-axis direction that is higher than the rigidity in the X-axis direction.

[0008] A semiconductor device according to the first embodiment comprises a membrane portion including a device region on which a plurality of semiconductor elements are formed, and a rim portion surrounding the membrane portion and being thicker than the membrane portion, wherein the width of the rim portion in the X-axis direction is greater than the width of the rim portion in the Y-axis direction.

[0009] A semiconductor device according to a third embodiment includes a membrane portion containing a device region on which a plurality of semiconductor elements are formed, and a rim portion surrounding the membrane portion and being thicker than the membrane portion, wherein the thickness of the rim portion at the point of intersection with the X axis is greater than the thickness at the point of intersection with the Y axis.

[0010] A semiconductor device according to a fourth embodiment includes a membrane portion containing a device region on which a plurality of semiconductor elements are formed, and a reinforcing member fixed to the wafer periphery surrounding the membrane portion, the reinforcing member having a width in the X-axis direction greater than the width in the Y-axis direction.

[0011] The semiconductor device according to the fifth aspect includes a membrane portion including a device region in which a plurality of semiconductor elements are formed, and a reinforcing member fixed to a wafer peripheral portion surrounding the membrane portion, the thickness of a portion intersecting the X-axis being larger than the thickness of a portion intersecting the Y-axis.

Brief Description of the Drawings

[0012] [Figure 1A] It is a flowchart for explaining a method of manufacturing a semiconductor device according to an embodiment (pre-measurement of wafer warpage amount). [Figure 1B] It is a flowchart for explaining a method of manufacturing a semiconductor device according to an embodiment. [Figure 2] It is a plan view of a semiconductor device (semiconductor wafer) according to the first embodiment. [Figure 3A] It is a cross-sectional view taken along the line X-X of FIG. 2. [Figure 3B] It is a cross-sectional view taken along the line Y-Y of FIG. 2. [Figure 4] It is a diagram for explaining the operation and effect of the first embodiment. [Figure 5] It is a diagram for explaining a method of manufacturing a semiconductor device according to the first embodiment. [Figure 6] It is a diagram for explaining the operation control of a spindle when manufacturing a semiconductor device according to the first embodiment. [Figure 7] It is a plan view of a semiconductor device (semiconductor wafer) according to a modification of the first embodiment. [Figure 8A] It is a cross-sectional view taken along the line X-X of FIG. 7. [Figure 8B] It is a cross-sectional view taken along the line Y-Y of FIG. 7. [Figure 9] It is a diagram for explaining the operation control of a spindle when manufacturing a semiconductor device according to a modification of the first embodiment. [Figure 10] It is a plan view of a semiconductor device (semiconductor wafer) according to the second embodiment. [Figure 11A] It is a cross-sectional view taken along the line I-I of FIG. 10. [Figure 11B]It is a cross-sectional view taken along line II-II of FIG. 10. [Figure 12] It is a plan view of a semiconductor device (semiconductor wafer) according to the third embodiment. [Figure 13A] It is a cross-sectional view taken along line X-X of FIG. 12. [Figure 13B] It is a cross-sectional view taken along line Y-Y of FIG. 12. [Figure 14] It is a diagram for explaining a method of manufacturing a semiconductor device according to the third embodiment. [Figure 15] It is a diagram for explaining the operation control of a blade when manufacturing a semiconductor device according to the third embodiment. [Figure 16] It is a plan view of a semiconductor device (semiconductor wafer) according to the fourth embodiment. [Figure 17A] It is a cross-sectional view taken along line X-X of FIG. 16. [Figure 17B] It is a cross-sectional view taken along line Y-Y of FIG. 16. [Figure 18] It is a plan view of a semiconductor device (semiconductor wafer) according to the fifth embodiment. [Figure 19A] It is a cross-sectional view taken along line X-X of FIG. 18. [Figure 19B] It is a cross-sectional view taken along line Y-Y of FIG. 18.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments do not limit the present invention. The drawings are schematic or conceptual, and the ratios of each part are not necessarily the same as those in reality. In the specification and the drawings, the same reference numerals are given to the same elements as those described above with respect to the existing drawings, and the detailed description will be omitted as appropriate.

[0014] <Method of Manufacturing a Semiconductor Device> An example of a semiconductor device manufacturing method according to the embodiment will be described with reference to Figures 1A and 1B. Figure 1A shows an example of a method for pre-measuring the amount of warpage of a semiconductor wafer. Figure 1B shows an example of a method for manufacturing a semiconductor device from the same type of semiconductor wafer based on the measured amount of warpage.

[0015] Step S1: Multiple semiconductor elements are formed in the device region of the surface (first main surface) of the semiconductor wafer. The device region is the region corresponding to device region D of semiconductor device 1 described later. The semiconductor element is, for example, a MOSFET (hereinafter referred to as FP trench MOS) in which a gate electrode and a field plate electrode are arranged in an insulating film embedded in a trench in the semiconductor layer. In this FP trench MOS, an insulating film is embedded in a trench formed in the semiconductor layer, and a gate electrode and a field plate electrode are arranged in this insulating film. Thus, the semiconductor element in this example has a trench structure that extends along a predetermined direction (for example, the X-axis direction or the Y-axis direction). The type of semiconductor element is not particularly limited and may be, for example, an IGBT, a diode, a thyristor, etc.

[0016] Step S2: The back surface (second main surface) of the semiconductor wafer is ground to form a rim. The semiconductor wafer is ground by back grinding. The thin area of ​​the semiconductor wafer that is ground becomes the membrane (corresponding to membrane portion 2 described later). The rim is an annular rim surrounding the multiple semiconductor elements formed in the device region. The thickness of the rim is greater than that of the device region. The rim formed in this step has a uniform width. That is, the rim of the semiconductor wafer has a constant radial length along the circumferential direction.

[0017] Step S3: The amount of warpage in the X-axis direction (first warpage) and the amount of warpage in the Y-axis direction (second warpage) are measured for the semiconductor wafer on which the rim portion has been formed. This step is performed using optical interferometry, a laser displacement meter, or the like. The X-axis direction is the direction of the axis passing through a predetermined position on the semiconductor wafer. The Y-axis direction is the direction intersecting the X-axis direction. In this embodiment, the X-axis passes through the center of the semiconductor wafer, and the Y-axis direction is perpendicular to the X-axis direction. In addition, in this embodiment, a notch (not shown) is formed on the Y-axis as a marker to indicate the crystal orientation of the semiconductor wafer.

[0018] As described above, the amount of warpage in the X-axis and Y-axis directions is measured for a semiconductor wafer on which multiple semiconductor elements are formed in the device region. When the trench of a semiconductor element (FP trench MOS) extends in the X-axis direction, the amount of warpage in the Y-axis direction may be greater than the amount of warpage in the X-axis direction. Not limited to trench structures, the amount of warpage in one of the X-axis and Y-axis directions may also be greater depending on the thickness of the metal film (source metal, etc.) formed on the surface of the semiconductor wafer, the pattern shape and size of the semiconductor element, or various conditions of the semiconductor element manufacturing process. According to the inventor's research, if the semiconductor wafer and semiconductor element are the same, the tendency of warpage of the semiconductor wafer will be almost the same.

[0019] Next, following the flow chart shown in Figure 1B, an example of a method for manufacturing a semiconductor device using the same type of semiconductor wafer as the semiconductor wafer in which the warpage was measured will be explained. Here, "same type of semiconductor wafer" refers to a semiconductor wafer that is identical to the semiconductor wafer in which the warpage was measured in at least one of the following aspects: material (silicon, silicon carbide, etc.), size (diameter, thickness), shape, model number / part number, and lot number.

[0020] Step S11: Multiple semiconductor elements are formed on the device region of the surface of a semiconductor wafer of the same type as the semiconductor wafer from which the warpage was measured. The material of the semiconductor wafer is not particularly limited, but silicon is an example. The semiconductor elements formed in this step are the same as the multiple semiconductor elements formed in step S1. Here, "same" means that the type, structure, and manufacturing process of the semiconductor elements are the same.

[0021] Step S12: The amount of warping in the X-axis direction and the Y-axis direction is measured for the semiconductor wafer on which multiple semiconductor elements were formed in step S11, and it is determined whether the amount of warping in the Y-axis direction is greater than the amount of warping in the X-axis direction. If the amount of warping in the Y-axis direction is greater than the amount of warping in the X-axis direction (i.e., the amount of warping in the X-axis direction is less than the amount of warping in the Y-axis direction), proceed to step S13; otherwise, proceed to step S14.

[0022] Step S13: A rim portion is formed on the semiconductor wafer, surrounding multiple semiconductor elements, with a rigidity in the Y-axis direction greater than the rigidity in the X-axis direction. In this application, the rigidity in the Y-axis direction refers to the degree of resistance to deformation of the annular rim portion in the YZ plane with respect to the stress of the semiconductor wafer (more specifically, the stress generated in the semiconductor wafer due to the surface structure of the semiconductor wafer). Similarly, the rigidity in the X-axis direction refers to the degree of resistance to deformation of the annular rim portion in the XZ plane with respect to the stress of the semiconductor wafer. Here, the YZ plane is a plane formed by the Y axis and the Z axis which is perpendicular to the X and Y axes. The XZ plane is a plane formed by the X axis and the Z axis. Specific embodiments of the rim portion will be described later.

[0023] Step S14: A rim is formed on the semiconductor wafer, surrounding multiple semiconductor elements, with rigidity in the X-axis direction being higher than rigidity in the Y-axis direction. Specific examples will be mentioned in the embodiments described later.

[0024] Step S15: A metal film (drain electrode, collector electrode, etc.) is formed on the back surface of the semiconductor wafer. Alternatively, ion implantation may be performed on the back surface of the semiconductor wafer before forming the metal film to form the n-type semiconductor region (drain region) of the MOSFET or the p-type semiconductor region (collector region) of the IGBT.

[0025] Step S16: The semiconductor wafer is diced to separate multiple semiconductor elements into individual chips. Specifically, the back surface of the semiconductor wafer is fixed to a dicing tape, and the semiconductor wafer is cut along the dicing line using a blade (rotating blade). Then, the individual semiconductor chips are removed from the dicing tape.

[0026] According to the semiconductor device manufacturing method described above, the amount of warpage in the X-axis and Y-axis directions of a semiconductor wafer with a uniform rim width is measured in advance. Then, when manufacturing a semiconductor device from the same type of semiconductor wafer, rim portions with different rigidities in the X-axis and Y-axis directions are formed based on the measurement results of the amount of warpage. This makes it possible to suppress the warping of the semiconductor wafer in a specific direction due to the surface structure of the semiconductor element. As a result, the difficulty of process flow can be reduced, and the productivity and quality of semiconductor devices can be improved.

[0027] The method described above is merely one example, and various variations are possible.

[0028] For example, step S2 may be omitted. That is, after step S1, the amount of warpage in the X-axis direction and the amount of warpage in the Y-axis direction are measured on a semiconductor wafer that has not undergone backside grinding. Even in this way, it is possible to understand the relative magnitudes of the warpage in the X-axis direction and the warpage in the Y-axis direction and perform step S12.

[0029] Alternatively, if step S2 is omitted, the amount of warpage of the semiconductor wafer may be measured in step S3, and a rim portion of the semiconductor wafer may be formed based on the measurement result. In this case, after step S3, step S11 is skipped, and the next step is performed instead of step S12. That is, based on the measurement result in step S3, a step is performed to determine whether the amount of warpage in the Y-axis direction is greater than the amount of warpage in the X-axis direction. If the amount of warpage in the Y-axis direction is greater than the amount of warpage in the X-axis direction, a rim portion is formed that surrounds multiple semiconductor elements and has a stiffness in the Y-axis direction that is greater than the stiffness in the X-axis direction. On the other hand, if the amount of warpage in the Y-axis direction is less than the amount of warpage in the X-axis direction, a rim portion is formed that surrounds multiple semiconductor elements and has a stiffness in the X-axis direction that is greater than the stiffness in the Y-axis direction.

[0030] Furthermore, it is possible to estimate the amount of warpage in the X-axis and Y-axis directions of a semiconductor wafer based on, for example, the type and structure of the semiconductor devices formed on the semiconductor wafer. Such estimations are made through semiconductor device manufacturing experience (accumulation of data, etc.), simulations, etc. A rim portion may be formed based on the estimated amount of warpage of the semiconductor wafer. In this case, steps S1 to S3 are omitted, and in step S12, the estimated values ​​are used as the amount of warpage in the X-axis and Y-axis directions. If the estimated amount of warpage in the Y-axis direction is greater than the estimated amount of warpage in the X-axis direction, a rim portion is formed that surrounds multiple semiconductor elements and has a stiffness in the Y-axis direction that is greater than the stiffness in the X-axis direction. On the other hand, if the estimated amount of warpage in the Y-axis direction is less than the estimated amount of warpage in the X-axis direction, a rim portion is formed that surrounds multiple semiconductor elements and has a stiffness in the X-axis direction that is greater than the stiffness in the Y-axis direction.

[0031] As described above, the "amount of warpage" in step S12 may be a measured value or an estimated value. Furthermore, the measured value may be a value measured on a semiconductor wafer of the same type as the semiconductor wafer on which the rim portion is formed, or a value measured on the semiconductor wafer on which the rim portion is formed.

[0032] The following describes the first to fifth embodiments of a semiconductor device having a rim portion with different rigidity in the X-axis and Y-axis directions. Herein, "semiconductor device" refers to a semiconductor wafer on which multiple semiconductor elements are formed in a device region.

[0033] (First Embodiment) A semiconductor device 1 according to the first embodiment will be described with reference to Figures 2, 3A, and 3B. Figure 2 is a plan view of the semiconductor device 1. Figure 3A is a cross-sectional view along line XX in Figure 2, and Figure 3B is a cross-sectional view along line YY in Figure 2.

[0034] The semiconductor device 1 comprises a membrane portion 2 including a device region D, and a rim portion 3 surrounding the membrane portion 2 and being thicker than the membrane portion 2. Multiple semiconductor elements 10 are formed in the device region D.

[0035] The width Wx of the rim portion 3 is greater than the width Wy of the rim portion 3. The width Wx is the length of the portion of the rim portion 3 that intersects the X-axis passing through the center of the semiconductor device 1, and is sometimes referred to as the "width in the X-axis direction". The width Wy is the length of the portion of the rim portion 3 that intersects the Y-axis, which passes through the center of the semiconductor device 1 and is perpendicular to the X-axis, and is sometimes referred to as the "width in the Y-axis direction". In this embodiment, the width of the rim portion 3 smoothly decreases from width Wx to width Wy along the circumferential direction, and then smoothly increases from width Wy to width Wx.

[0036] The inner edge shape of the rim portion 3 in this embodiment (i.e., the shape of the membrane portion 2) is elliptical, oblong, or egg-shaped. In the example in Figure 2, the minor axis of the ellipse coincides with the X axis, and the major axis coincides with the Y axis.

[0037] As described above, in the first embodiment, since the width Wx is greater than the width Wy, the rigidity of the rim portion 3 in the Y-axis direction is higher than the rigidity in the X-axis direction. Therefore, as schematically shown in Figure 4, the amount of warping in the Y-axis direction (represented by symbol Y2) of the semiconductor device 1 on which the rim portion 3 is formed is smaller than the amount of warping in the Y-axis direction (represented by symbol Y1) of the semiconductor device on which a rim portion of uniform width is formed, and approaches the amount of warping in the X-axis direction. As a result, warping of the semiconductor device (semiconductor wafer) in a specific direction can be suppressed, and the in-plane warping can be made more uniform.

[0038] In this embodiment, the difference between the curvature in the X-axis direction and the curvature in the Y-axis direction was reduced by decreasing the curvature in the Y-axis direction. Alternatively, the difference between the curvature in the X-axis direction and the curvature in the Y-axis direction may be reduced by increasing the curvature in the X-axis direction.

[0039] Furthermore, in the pre-measurement of wafer warpage, if the warpage in the X-axis direction is greater than the warpage in the Y-axis direction, a rim portion with a width in the Y-axis direction greater than the width in the X-axis direction should be constructed. For example, in Figure 2, the ellipse of the inner edge of the rim portion 3 can be made into a horizontally elongated ellipse by rotating it 90 degrees around the center of the semiconductor wafer.

[0040] <Method for forming the rim portion of semiconductor device 1> Here, an example of a manufacturing method for the rim portion 3 according to the first embodiment will be described with reference to Figures 5 and 6. Figure 5 shows the process of grinding a semiconductor wafer with a spindle, and Figure 6 is a diagram for explaining the operation control of the spindle. Note that in Figure 6, attention is focused on the right rim (i.e., the side where X>0) of the left and right rims shown in Figure 5.

[0041] A grinding wheel 210 is attached to the underside of the spindle 200. The semiconductor wafer 100 is fixed to a turntable (not shown) with its back surface facing upwards. When grinding the semiconductor wafer 100, the semiconductor wafer 100 rotates with the turntable around axis A1, and the spindle 200 rotates around axis A2. The spindle 200 (grinding wheel 210) is positioned in the X-axis and Z-axis directions (vertical direction) by an external control device (not shown). As a result, the area of ​​the back surface of the semiconductor wafer 100 corresponding to the device area D is ground.

[0042] Here, with reference to Figure 6, the position control of the spindle 200 will be explained in detail. As shown in Figure 6, the spindle 200 is controlled to move periodically in the positive or negative direction of the X-axis around the central axis CA1, while also moving in the negative direction of the Z-axis. Since the central axis CA1 is parallel to the Z-axis, the inner wall of the rim portion 3 is approximately perpendicular to the surface of the membrane portion 2.

[0043] In Figure 6, the period Tw is the time it takes for the semiconductor wafer 100 to complete one rotation. During the period Tw, the spindle 200 moves (vibrates) alternately in the positive or negative direction of the X axis for two periods along the sine curve. This forms a rim portion 3 in which the width in the X direction is greater than the width in the Y direction. As shown in Figure 2, a rim portion 3 is formed in which the width smoothly changes from width Wx to width Wy (and from width Wy to width Wx) along the circumferential direction. Note that the spindle 200 may move along a waveform other than a sine curve, such as a triangular wave. Generally speaking, the spindle 200 should move along a waveform that repeats two maximums and two minimums in the X direction during the period Tw.

[0044] <Modified form of the first embodiment> A modified example of the first embodiment will be described with reference to Figures 7, 8A, and 8B. Figure 7 is a plan view of the semiconductor device 1A according to this modified example. Figure 8A is a cross-sectional view along line XX in Figure 7, and Figure 8B is a cross-sectional view along line YY in Figure 7. Note that the multiple semiconductor elements 10 are not shown in Figure 7.

[0045] The semiconductor device 1A comprises a membrane portion 2 including a device region D, a rim portion 3 surrounding the membrane portion 2 and thicker than the membrane portion 2, and a slope portion 3a provided inside the rim portion 3. The slope portion 3a connects the rim portion 3 and the membrane portion 2. The surface of the slope portion 3a is oblique to the surfaces of the membrane portion 2 and the rim portion 3. In this example, the slope portion 3a has a uniform width, but it may have a non-uniform width.

[0046] <Method for forming the rim portion of semiconductor device 1A> Referring to Figure 9, an example of a manufacturing method for the rim portion 3 according to this modified example will be explained. Figure 9 is a diagram for explaining the operation control of the spindle. Note that in Figure 9, attention is focused on the right rim (i.e., the side where X>0) of the left and right rims shown in Figure 8A. However, the operation control of the spindle in the XZ plane shown in Figure 9 may also be considered in the YZ plane by focusing on the right rim (i.e., the side where Y>0) of the left and right rims shown in Figure 8B.

[0047] As shown in Figure 9, the spindle 200 moves periodically in the positive or negative direction of the X-axis around the central axis CA2 while moving in the negative direction of the Z-axis. Since the central axis CA2 is inclined with respect to the Z-axis, a slope portion 3a is formed.

[0048] (Second embodiment) Next, a second embodiment will be described. In the second embodiment, a rim portion is constructed in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction by providing a slope portion with an uneven width.

[0049] A semiconductor device 1B according to the second embodiment will be described with reference to Figures 10, 11A, and 11B. Figure 10 is a plan view of the semiconductor device 1B. Figure 11A is a cross-sectional view along line II in Figure 10, and Figure 11B is a cross-sectional view along line II-II in Figure 10. Note that the multiple semiconductor elements 10 are not shown in Figure 10.

[0050] The semiconductor device 1B comprises a membrane portion 2 including a device region D, and a rim portion 3 surrounding the membrane portion 2 and being thicker than the membrane portion 2.

[0051] The rim portion 3 according to the second embodiment includes a uniform rim portion 3b having a uniform width and a slope portion 3c provided inside the uniform rim portion 3b. The slope portion 3c has a width in the X-axis direction that is greater than its width in the Y-axis direction. The width of the slope portion 3c changes smoothly along the circumferential direction. As shown in Figures 11A and 11B, the uniform rim portion 3b has a width in both the X-axis direction and the Y-axis direction that is Wr, whereas the slope portion 3c has a width in the X-axis direction Wsx that is greater than its width in the Y-axis direction Wsy. The width of the slope portion is changed by varying the slope angle.

[0052] As described above, in the second embodiment, by making the width of the slope portion different in the X-axis direction and the Y-axis direction, a rim portion is constructed in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction.

[0053] (Third embodiment) Next, a third embodiment will be described. In the third embodiment, the thickness of the rim portion having a uniform width is varied along the circumferential direction to create a rim portion in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction.

[0054] A semiconductor device 1C according to a third embodiment will be described with reference to Figures 12, 13A, and 13B. Figure 12 is a plan view of the semiconductor device 1C. Figure 13A is a cross-sectional view along line XX in Figure 12, and Figure 13B is a cross-sectional view along line YY in Figure 12. Note that the multiple semiconductor elements 10 are not shown in Figure 12.

[0055] The semiconductor device 1C comprises a membrane portion 2 including a device region D on which multiple semiconductor elements are formed, and a rim portion 3 surrounding the membrane portion 2 and being thicker than the membrane portion 2.

[0056] The rim portion 3 according to the third embodiment has a uniform width. The thickness of the rim portion 3 in the X-axis direction is greater than the thickness in the Y-axis direction. As shown in Figures 13A and 13B, the thickness Tx in the X-axis direction of the rim portion 3 is greater than the thickness Ty in the Y-axis direction. Here, thickness Tx is the thickness of the portion of the rim portion 3 that intersects with the X-axis passing through the center of the semiconductor device 1, and is sometimes referred to as the "thickness in the X-axis direction". Thickness Ty is the thickness of the portion of the rim portion 3 that intersects with the Y-axis which passes through the center of the semiconductor device 1 and is perpendicular to the X-axis, and is sometimes referred to as the "thickness in the Y-axis direction".

[0057] As described above, in the third embodiment, by making the thickness of the rim portion different in the X-axis direction and the Y-axis direction, a rim portion is constructed in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction.

[0058] Furthermore, the rim portion in the third embodiment is not limited to having a uniform width; for example, as in the first embodiment, the width in the X-axis direction and the width in the Y-axis direction may be different.

[0059] <Method for forming the rim portion of semiconductor device 1C> An example of a manufacturing method for the rim portion 3 according to the third embodiment will be described.

[0060] First, a temporary rim portion with a uniform width is formed by grinding the area on the back surface of the semiconductor wafer that corresponds to the device area. The temporary rim portion corresponds to the rim portion formed in step S2 described above. Furthermore, the temporary rim portion is not limited to having a uniform width; for example, it may be formed so that the width in the X-axis direction and the width in the Y-axis direction are different, as in the first embodiment.

[0061] Next, as shown in Figure 14, the upper surface of the temporary rim is ground to form a rim where the thickness in the X-axis direction is greater than the thickness in the Y-axis direction. The temporary rim is ground using a blade 300 that rotates around the rotation axis A3. With the semiconductor wafer 100 rotating around the rotation axis A1, the blade 300 is applied to the upper surface of the temporary rim to adjust the thickness of the temporary rim.

[0062] Specifically, as shown in Figure 15, the blade 300 moves periodically in the positive or negative direction of the Z axis around the central axis CA3. During the period Tw in which the semiconductor wafer 100 rotates once, the blade 300 alternately moves (vibrates) in the positive or negative direction of the Z axis for two periods along a sine curve. This makes it possible to form a rim portion where the thickness is maximum in the X-axis direction and minimum in the Y-axis direction, and the thickness changes smoothly along the circumferential direction. Note that the blade 300 may move along a waveform other than a sine curve, such as a triangular wave. Generally speaking, the blade 300 should move along a waveform that repeats a maximum and minimum twice in the X direction during the period Tw.

[0063] (Fourth embodiment) Next, a fourth embodiment will be described. In the fourth embodiment, a rim portion is constructed in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction by fixing a reinforcing member to the wafer periphery (periphery of the semiconductor wafer) having the same thickness as the membrane portion.

[0064] A semiconductor device 1D according to the fourth embodiment will be described with reference to Figures 16, 17A, and 17B. Figure 16 is a plan view of the semiconductor device 1D. Figure 17A is a cross-sectional view along line XX in Figure 16, and Figure 17B is a cross-sectional view along line YY in Figure 16. Note that multiple semiconductor elements 10 are not shown in Figure 16.

[0065] The semiconductor device 1D includes a membrane portion 2 containing a device region D on which multiple semiconductor elements are formed, a wafer peripheral portion 2p surrounding the membrane portion 2, and a reinforcing member 4 fixed on the wafer peripheral portion 2p. In this embodiment, the wafer peripheral portion 2p has the same thickness as the membrane portion 2.

[0066] The reinforcing member 4 is a ring-shaped member whose width in the X-axis direction is greater than its width in the Y-axis direction. The material of the reinforcing member 4 is not particularly limited, but examples include glass, resin, and metal.

[0067] The reinforcing member 4 is fixed to the rim portion 3 with an adhesive. For example, an acrylic resin adhesive is used. However, other resin adhesives, such as polyethylene, polypropylene, polyamide, polyvinyl alcohol, triacetylcellulose, methacrylic resin, polystyrene, and polyvinylidene fluoride, may also be used. Furthermore, the fixing method is not limited to adhesive; the reinforcing member 4 may also be fixed to the rim portion 3 using double-sided adhesive tape. Alternatively, the reinforcing member 4 may be fixed to the rim portion 3 using a low-melting-point metal or alloy (for example, including tin (Sn) and bismuth (Bi)).

[0068] As described above, in the fourth embodiment, a rim portion is constructed in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction by providing reinforcing members 4 with different widths in the X-axis direction and the Y-axis direction on the wafer peripheral edge 2p.

[0069] <Method for forming the rim portion of semiconductor device 1D> An example of a method for manufacturing the rim portion according to the fourth embodiment will be described.

[0070] First, the entire back surface of the semiconductor wafer on which multiple semiconductor elements are formed is ground. Then, the reinforcing member 4 is fixed to the wafer periphery 2p using an adhesive or the like. This creates a rim portion in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction.

[0071] Alternatively, as described in step S2 above, the back surface of the semiconductor wafer may be ground to form a rim portion with a uniform width, and the reinforcing member 4 may be fixed to the rim portion.

[0072] Furthermore, in the dicing process, the wafer periphery to which the reinforcing member 4 is fixed is cut with a blade, and then the membrane portion 2 is diced to separate the multiple semiconductor elements into individual pieces.

[0073] (Fifth embodiment) Next, a fifth embodiment will be described. In the fifth embodiment, the thickness of the reinforcing member fixed to the wafer periphery (the periphery of the semiconductor wafer) is varied along the circumferential direction to create a rim portion in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction. The fifth embodiment will be described below, focusing on the differences from the fourth embodiment.

[0074] A semiconductor device 1E according to the fifth embodiment will be described with reference to Figures 18, 19A, and 19B. Figure 18 is a plan view of the semiconductor device 1E. Figure 19A is a cross-sectional view along line XX in Figure 18, and Figure 19B is a cross-sectional view along line YY in Figure 18. Note that the multiple semiconductor elements 10 are not shown in Figure 18.

[0075] The semiconductor device 1E includes a membrane portion 2 containing a device region D on which multiple semiconductor elements are formed, a wafer peripheral portion 2p surrounding the membrane portion 2, and a reinforcing member 5 fixed on the wafer peripheral portion 2p.

[0076] The reinforcing member 5 is a ring-shaped member in which the thickness in the X-axis direction (thickness at the point where it intersects the X-axis) is greater than the thickness in the Y-axis direction (thickness at the point where it intersects the Y-axis). The material of the reinforcing member 5 is not particularly limited, but examples include glass, resin, and metal.

[0077] The reinforcing member 5 is fixed to the rim portion 3 with adhesive. The type of adhesive is the same as that described in the fourth embodiment.

[0078] As described above, in the fifth embodiment, a rim portion is constructed in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction by providing reinforcing members 5 with different thicknesses in the X-axis direction and the Y-axis direction on the wafer peripheral edge 2p.

[0079] <Method for forming the rim portion of semiconductor device 1E> An example of a method for manufacturing the rim portion according to the fifth embodiment will be described.

[0080] First, the entire back surface of the semiconductor wafer on which multiple semiconductor elements are formed is ground. Then, the reinforcing member 5 is fixed to the wafer periphery 2p using an adhesive or the like. This creates a rim portion in which the rigidity in the Y-axis direction is higher than the rigidity in the X-axis direction.

[0081] In addition, the wafer peripheral portion 2p described in the fourth and fifth embodiments does not have to be the same thickness as the membrane portion 2. For example, as in step S2 above, a temporary rim portion that is thicker than the membrane portion may be formed, and the rim portion may be constructed by fixing the reinforcing member 5 to the temporary rim portion.

[0082] According to at least one embodiment described above, it is possible to suppress the bending of a semiconductor wafer on which multiple semiconductor elements are formed in a specific direction.

[0083] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0084] 1,1A,1B,1C,1D,1E Semiconductor equipment 2 Membrane section 2p wafer edge 3. Rim section 3a Slope section 3b Uniform rim section 3c Slope section 4,5 Reinforcement members 10 Semiconductor devices 100 semiconductor wafers 200 spindles 210 Sharpening Stones 300 blades A1, A2, A3 rotation axis CA1,CA2,CA3 Center axis D device area Tw period

Claims

1. Multiple semiconductor elements are formed in the device region of the first main surface of a semiconductor wafer. If the first amount of warpage in the X-axis direction of the semiconductor wafer is smaller than the second amount of warpage in the Y-axis direction of the semiconductor wafer, a rim portion is formed on the semiconductor wafer that surrounds the plurality of semiconductor elements and has a rigidity in the Y-axis direction that is higher than the rigidity in the X-axis direction. A method for manufacturing a semiconductor device.

2. A method for manufacturing a semiconductor device according to claim 1, wherein a rim portion is formed by grinding a region of the second main surface of the semiconductor wafer that corresponds to the device region, the rim portion having a width in the X-axis direction greater than the width in the Y-axis direction.

3. A method for manufacturing a semiconductor device according to claim 1, wherein a rim portion is formed by grinding a region of the second main surface of the semiconductor wafer that corresponds to the device region, thereby forming a rim portion that includes a uniform rim portion having a uniform width and a slope portion whose width in the X-axis direction is greater than its width in the Y-axis direction.

4. A temporary rim is formed by grinding the region of the second main surface of the semiconductor wafer that corresponds to the device region. A method for manufacturing a semiconductor device according to claim 1, wherein the upper surface of the temporary rim portion is ground to form the rim portion in which the thickness of the portion intersecting the X-axis is greater than the thickness of the portion intersecting the Y-axis.

5. The method for manufacturing a semiconductor device according to claim 1, wherein the rim portion is formed by fixing a reinforcing member to the peripheral edge of the semiconductor wafer, the reinforcing member having a rigidity in the Y-axis direction that is higher than the rigidity in the X-axis direction.

6. The method for manufacturing a semiconductor device according to claim 5, wherein the reinforcing member has a width in the X-axis direction that is greater than the width in the Y-axis direction.

7. The method for manufacturing a semiconductor device according to claim 5, wherein the thickness of the reinforcing member at the portion intersecting the X-axis is greater than the thickness at the portion intersecting the Y-axis.

8. The method for manufacturing a semiconductor device according to any one of claims 1 to 7, wherein the plurality of semiconductor elements have a trench structure extending along the X-axis.

9. A membrane portion including a device region on which multiple semiconductor elements are formed, Surrounding the membrane portion is a rim portion which is thicker than the membrane portion, A semiconductor device equipped with, A semiconductor device wherein the width of the rim portion in the X-axis direction is greater than the width of the rim portion in the Y-axis direction.

10. The semiconductor device according to claim 9, wherein the inner edge shape of the rim portion is elliptical, oblong, or egg-shaped.

11. The semiconductor device according to claim 9, wherein the rim portion comprises a uniform rim portion having a uniform width and a slope portion provided inside the uniform rim portion, the slope portion having a width in the X-axis direction greater than the width in the Y-axis direction.

12. A membrane portion including a device region on which multiple semiconductor elements are formed, Surrounding the membrane portion is a rim portion which is thicker than the membrane portion, Equipped with, The aforementioned rim portion has a thickness greater at the point where it intersects the X-axis than at the point where it intersects the Y-axis, in a semiconductor device.

13. A membrane portion including a device region on which multiple semiconductor elements are formed, A reinforcing member is fixed to the wafer periphery surrounding the membrane portion, and its width in the X-axis direction is greater than its width in the Y-axis direction. A semiconductor device equipped with a semiconductor device.

14. A membrane portion including a device region on which multiple semiconductor elements are formed, A reinforcing member is fixed to the wafer periphery surrounding the membrane portion, and the thickness of the portion intersecting the X-axis is greater than the thickness of the portion intersecting the Y-axis. A semiconductor device equipped with a semiconductor device.

15. The semiconductor device according to any one of claims 9 to 14, wherein the plurality of semiconductor elements have a trench structure extending along the X-axis.

Images