Ion implantation apparatus, mask set, and method for manufacturing a semiconductor device

Abstract

To control the warping of semiconductor substrates. [Solution] The ion implantation apparatus comprises an ion beam irradiation unit that irradiates a ribbon-shaped ion beam, a target substrate holding unit that holds a target substrate placed in the path of the ion beam, a first mask holding unit that holds a first mask placed in front of the target substrate in the path, and a second mask holding unit that holds a second mask placed between the first mask and the target substrate in the path. The first mask has a first aperture pattern through which the ion beam can pass. The second mask has a second aperture pattern through which the ion beam can pass.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to an ion implantation apparatus, a mask set, and a method for manufacturing a semiconductor device. [Background technology]

[0002] In recent years, semiconductor devices such as 3D memory have become known. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] U.S. Patent Application Publication No. 2018 / 0342413 [Patent Document 2] Japanese Patent Application Publication No. 9-134702 [Patent Document 3] International Publication No. 2006 / 096818 [Patent Document 4] Japanese Patent Application Publication No. 9-245722 [Overview of the project] [Problems that the invention aims to solve]

[0004] One of the problems that the invention aims to solve is controlling the warping of semiconductor substrates. [Means for solving the problem]

[0005] The ion implantation apparatus of the embodiment comprises an ion beam irradiation unit that irradiates a ribbon-shaped ion beam, a target substrate holding unit that holds a target substrate placed in the path of the ion beam, a first mask holding unit that holds a first mask placed in front of the target substrate in the path, and a second mask holding unit that holds a second mask placed between the first mask and the target substrate in the path. The first mask has a first aperture pattern through which the ion beam can pass. The second mask has a second aperture pattern through which the ion beam can pass. [Brief explanation of the drawing]

[0006] [Figure 1] It is a schematic diagram for explaining an example of a target substrate. [Figure 2] It is a schematic diagram for explaining a first example of an ion implantation method. [Figure 3] It is a schematic diagram for explaining a second example of an ion implantation method. [Figure 4] It is a schematic diagram for explaining the warped shape of a semiconductor substrate. [Figure 5] It is a schematic diagram for explaining the warped shape of a semiconductor substrate. [Figure 6] It is a schematic diagram for explaining the warped shape of a semiconductor substrate. [Figure 7] It is a schematic diagram for explaining a first example of a dose amount distribution. [Figure 8] It is a schematic diagram for explaining a second example of a dose amount distribution. [Figure 9] It is a schematic diagram for explaining the relationship between an ion beam and a target substrate. [Figure 10] It is a schematic diagram for explaining the relationship between an ion beam and a target substrate. [Figure 11] It is a schematic diagram showing a first configuration example of an ion implantation apparatus. [Figure 12] It is a schematic diagram showing a first configuration example of an ion implantation apparatus. [Figure 13] It is a schematic diagram showing a second configuration example of an ion implantation apparatus. [Figure 14] It is a schematic diagram showing a second configuration example of an ion implantation apparatus. [Figure 15] It is a schematic diagram showing a configuration example of an ion beam receiving part. [Figure 16] It is a schematic diagram showing a configuration example of an ion beam receiving part. [Figure 17] It is a schematic diagram showing a structural example of a mask set. [Figure 18] It is a schematic diagram for explaining an example of an ion implantation method and a method for manufacturing a semiconductor device. [Figure 19]It is a schematic diagram for explaining an example of an ion implantation method and a method of manufacturing a semiconductor device. [Figure 20] It is a schematic diagram showing a modified example of a mask set. [Figure 21] It is a schematic diagram showing a modified example of a mask set. [Figure 22] It is a schematic diagram for explaining an example of a method of transporting a target substrate after ion implantation. [Figure 23] It is a schematic diagram for explaining an example of a method of transporting a target substrate after ion implantation.

Embodiments for Carrying Out the Invention

[0007] Hereinafter, embodiments will be described with reference to the drawings. The relationship between the thickness and the planar dimensions of each component shown in the drawings, the ratio of the thicknesses of each component, etc. may differ from the actual ones. Also, in the embodiments, substantially the same components are denoted by the same reference numerals and the description thereof is omitted as appropriate.

[0008] First, an example of a target substrate on which ion implantation is performed using the ion implantation apparatus of the embodiment will be described. FIG. 1 is a schematic diagram for explaining an example of a target substrate. FIG. 1 shows an X-axis, a Y-axis, and a Z-axis. The X-axis, the Y-axis, and the Z-axis intersect perpendicularly to each other.

[0009] Examples of the target substrate include semiconductor substrates used in semiconductor devices. The planar shape of the semiconductor substrate is, for example, circular. Examples of semiconductor devices include, but are not limited to, NAND-type flash memories. A NAND-type flash memory can be manufactured, for example, by bonding a semiconductor substrate 101 and a semiconductor substrate 102 as shown in FIG. 1. The semiconductor substrate 101 has a semiconductor wafer 111 and a layer 112 formed on the semiconductor wafer 111. The semiconductor substrate 102 has a semiconductor wafer 121 and a layer 122 formed on the semiconductor wafer 121. The X-axis and the Y-axis are, for example, in the plane direction of the semiconductor substrate 101 or the semiconductor substrate 102. The Z-axis is in the thickness direction of the semiconductor substrate 101 or the semiconductor substrate 102.

[0010] The semiconductor wafer 111 has a surface 111a on which layer 112 is formed, and a surface (back surface) 111b opposite to surface 111a. The semiconductor wafer 111 is, for example, a silicon wafer. Layer 112 has peripheral circuits, including CMOS circuits, for example, in NAND flash memory.

[0011] The semiconductor wafer 121 has a surface 121a on which layer 122 is formed, and a surface (back surface) 121b opposite to surface 121a. The semiconductor wafer 121 is, for example, a silicon wafer. Layer 122 includes, for example, a memory cell array in NAND flash memory.

[0012] The surfaces of layer 112 and layer 122 are bonded together. This electrically connects the peripheral circuitry and the memory cell array.

[0013] Semiconductor substrates used in semiconductor devices may have warping in at least one direction, for example, the X-axis and Y-axis. For example, semiconductor substrate 102 may have greater warping than semiconductor substrate 101, greater warping along the X-axis than along the Y-axis, and may warp convexly from surface 121a to surface 121b. The warping of a semiconductor substrate increases as, for example, the thickness and number of layers formed on the surface of the semiconductor substrate increase.

[0014] For example, if there is a large difference in warpage between semiconductor substrate 101 and semiconductor substrate 102, defects such as misalignment of the bonding position between semiconductor substrate 101 and semiconductor substrate 102 (so-called overlay anomaly) or the creation of unbonded areas at the edges of the substrates may occur when bonding them. Therefore, it is preferable to reduce the difference in warpage between semiconductor substrate 101 and semiconductor substrate 102 before bonding.

[0015] As a method to reduce the difference in warpage between semiconductor substrate 101 and semiconductor substrate 102, it is preferable to implant ions into at least a portion of at least one of the semiconductor substrates, semiconductor substrate 101 and semiconductor substrate 102. In the region where ions are implanted, the tensile or compressive stress of the implanted semiconductor substrate changes. As a result, for example, in regions where the tensile or compressive stress is high, the stress decreases, and thus the warpage can be reduced. Examples of ions include arsenic ions, germanium ions, argon ions, boron fluoride ions, nitrogen ions, carbon ions, and boron ions.

[0016] Figure 2 is a schematic diagram illustrating a first example of an ion implantation method. In this first example of an ion implantation method, ion implantation is performed to reduce the warpage of a semiconductor substrate. As shown in Figure 2, an ion beam IB containing the above ions is selectively irradiated onto the front (back) surface 121b of the semiconductor wafer 121 to reduce the warpage of the semiconductor substrate 102 in the X-axis direction, thereby implanting ions into the semiconductor wafer 121. This reduces the warpage of the semiconductor substrate 102, thereby reducing the difference in warpage between the semiconductor substrate 101 and the semiconductor substrate 102.

[0017] Figure 3 is a schematic diagram illustrating a second example of the ion implantation method. In this second example of the ion implantation method, ion implantation is performed to intentionally increase the warpage of the semiconductor substrate. As shown in Figure 3, ions are implanted into the semiconductor wafer 111 by selectively irradiating the surface (back surface) 111b of the semiconductor wafer 111 with an ion beam IB so that the warpage of the semiconductor substrate 101 in the X-axis direction is increased. This makes it possible to reduce the difference in warpage between the semiconductor substrate 101 and the semiconductor substrate 102 by forming a warpage on the semiconductor substrate 101 that is similar to that of the semiconductor substrate 102.

[0018] The difference between the warpage in the X-axis direction and the warpage in the Y-axis direction of a semiconductor substrate such as semiconductor substrate 101 or semiconductor substrate 102 can be adjusted by creating a difference in the amount of ions implanted in the ion beam IB within the plane, according to the warpage shape of the semiconductor substrate, thereby forming the above-mentioned ion dose distribution.

[0019] Figures 4, 5, and 6 are schematic diagrams illustrating the warp shape of a semiconductor substrate. Figures 4, 5, and 6 show the magnitude of the warp in the X-axis, Y-axis, and Z-axis directions of the semiconductor substrate. Figures 4 and 5 show that the warp in the X-axis direction passing through the center of the semiconductor substrate is greater than the warp in the Y-axis direction passing through the center of the semiconductor substrate, and that the warp is greater from the center of the semiconductor substrate toward both ends of the semiconductor substrate. In this case, it is preferable to form a dose distribution in which the dose amount increases from the center of the semiconductor substrate toward both ends in the X-axis direction. To reduce such warp of a semiconductor substrate, for example, 1 × 10 15 cm 2 It is preferable to have a high dose amount as described above. Alternatively, a dose distribution may be formed in which the dose amount decreases from the center of the semiconductor substrate toward both ends in the Y-axis direction. This makes it possible to adjust the warp shape of the semiconductor substrate to a shape with very little warp in both the X-axis and Y-axis directions, for example, as shown in Figure 6 (e.g., flat).

[0020] Figure 7 is a schematic diagram illustrating a first example of the dose distribution of a target substrate 100, which is a semiconductor substrate 101 or a semiconductor substrate 102. The back surface of the target substrate 100 has a high dose region 100A and a low dose region 100B. The X and Y axes are, for example, the plane directions of the target substrate 100. The Z axis is the thickness direction of the target substrate 100.

[0021] The high-dose region 100A is a region with a higher dose than the low-dose region 100B. The high-dose region 100A is provided, for example, in the X-axis direction and extends in a fan shape from the center C of the target substrate 100 toward the periphery of the target substrate 100. Figure 7 shows a pair of high-dose regions 100A. The pair of high-dose regions 100A are arranged to face each other with the center C in the X-axis direction. By forming a pair of fan-shaped high-dose regions 100A, the target substrate 100 having a convex warp in the X-axis direction can be made flat. The dose in the high-dose region 100A is 1 × 10⁻¹⁶ 15 / cm 2 It is preferable that the above conditions are met. 1 × 1015 / cm 2 By doing so, the warping of the target substrate 100 can be sufficiently adjusted.

[0022] The low-dose region 100B is a region with a lower dose than the high-dose region 100A. The low-dose region 100B is provided, for example, in the Y-axis direction and extends in a fan shape from the center C of the target substrate 100 toward the periphery of the target substrate 100. Figure 7 shows a pair of low-dose regions 100B. The pair of low-dose regions 100B are arranged to face each other with the center C in the X-axis direction. The low-dose region 100B does not necessarily contain the same type of ions as the ions injected into the high-dose region 100A.

[0023] Figure 8 is a schematic diagram illustrating a second example of the dose distribution of the target substrate 100. Figure 8 differs from Figure 7 in that the high-dose region 100A is formed in a linear shape, passing through the center C in the Y-axis direction and separating the low-dose region 100B. By forming the high-dose region 100A in a linear shape, for example, a convex curvature along the X-axis direction can be formed on a flat target substrate 100. Further explanation of the high-dose region 100A can be found by referring to the explanation of the high-dose region 100A in Figure 7 as appropriate.

[0024] Figure 8 shows a pair of low-dose regions 100B. The pair of low-dose regions 100B are arranged opposite each other in the X-axis direction, with the high-dose region 100A in between. Further explanation of the low-dose regions 100B can be found by referring to the explanation of the low-dose regions 100B in Figure 7 as appropriate.

[0025] Figures 9 and 10 are schematic diagrams illustrating the relationship between the ion beam IB and the target substrate 100. Figures 9 and 10 schematically show the target substrate 100 as viewed from a direction along the path of the ion beam IB. The X and Y axes represent, for example, the planar directions of the target substrate 100. The Z axis represents the thickness direction of the target substrate 100. In Figures 9 and 10, the movement directions of the ion beam IB and the target substrate 100 are indicated by dotted arrows.

[0026] For example, 1×10 14 / cm 2 In the case of the following low dose amounts, ion implantation can be performed using a spot-shaped ion beam IB. Since the spot-shaped ion beam IB can be scanned along the X-axis direction, as shown in FIG. 9, by scanning the ion beam IB in the X-axis direction and scanning the target substrate 100, for example, in the Y-axis direction, the back surface of the target substrate 100 can be irradiated with the ion beam IB to perform ion implantation. In this case, it is easy to control the dose amount within the plane of the target substrate 100.

[0027] However, for example, 1×10 15 / cm 2 When a high dose amount of 1 or more is required, it is necessary to perform ion implantation using a ribbon-shaped ion beam IB. For example, in the case of a horizontally long ribbon-shaped ion beam IB, since the ion beam IB is fixed at the same position without being scanned in the X-axis direction, as shown in FIG. 10, by scanning the target substrate 100, for example, in the Y-axis direction without scanning the ion beam IB, the back surface of the target substrate 100 can be irradiated with the ion beam IB to perform ion implantation. In this case, it is difficult to control the dose amount within the plane of the target substrate 100. Therefore, it becomes difficult to form a dose amount distribution as shown in FIGS. 7 and 8. On the other hand, a method of forming a mask having an opening pattern on the back surface of the target substrate 100 using, for example, photolithography technology and performing ion implantation through the mask can be considered. However, in the above method, since it is necessary to form different masks according to the planar shape of the high dose amount region to be formed, the manufacturing cost increases.

[0028] Therefore, in the embodiment, by selectively irradiating the back surface of the target substrate 100 with a ribbon-shaped ion beam IB through a mask set in which a plurality of masks are combined to perform ion implantation, a dose amount distribution including a high dose amount region as shown in FIGS. 7 and 8 is formed.

[0029] Figures 11 and 12 are schematic diagrams showing a first configuration example of an ion implantation apparatus in an embodiment. The first configuration example is an ion implantation apparatus capable of irradiating a horizontally elongated ribbon-shaped ion beam IB onto a target substrate 100. Figure 11 shows a schematic diagram of the first configuration example of the ion implantation apparatus from the top view. Figure 12 shows a schematic diagram of the first configuration example of the ion implantation apparatus from the side view.

[0030] Figures 13 and 14 are schematic diagrams showing a second configuration example of an ion implantation apparatus in an embodiment. The second configuration example is an ion implantation apparatus capable of irradiating a target substrate 100 with a vertically elongated ribbon-shaped ion beam IB. Figure 13 shows a schematic diagram of the second configuration example of the ion implantation apparatus from the top view. Figure 14 shows a schematic diagram of the second configuration example of the ion implantation apparatus from the side view.

[0031] The ion implantation apparatus comprises an ion beam irradiation unit 1 and an ion beam receiving unit 2.

[0032] The ion beam irradiation unit 1 can generate an ion beam IB. The ion beam irradiation unit 1 includes an ion source 11, an extraction electrode 12, an analyzer magnet 13, a mass slit 14, a collector magnet 15, and an electron neutralizer 16.

[0033] The ion source 11 can generate ions.

[0034] The extraction electrode 12 can extract ions generated by the ion source 11 to generate an ion beam IB.

[0035] The analyzer magnet 13 is installed downstream of the extraction electrode 12 in the middle of the ion beam IB path. The analyzer magnet 13 generates a magnetic field and passes the ion beam IB through the magnetic field, thereby removing ions other than those having a predetermined mass and valency from the ion beam IB and outputting them to the mass slit 14.

[0036] The mass slit 14 selectively allows the ion beam IB from the analyzer magnet 13 to pass through while partially blocking it, thereby narrowing the ion beam IB.

[0037] In the first configuration example, the collector magnet 15 can widen the ion beam IB from the mass slit 14 horizontally, thereby making the ion beam IB into a horizontally elongated ribbon shape. In the second configuration example, it can widen the ion beam IB vertically, thereby making the ion beam IB into a vertically elongated ribbon shape. Examples of the collector magnet 15 include a magnetic field filter and an electric field filter.

[0038] The electron neutralizer 16 is positioned, for example, between the collector magnet 15 and the mask set holder 22 in the path of the ion beam IB. The electron neutralizer 16 can generate plasma to neutralize positive charges in the ion beam IB. An example of the electron neutralizer 16 is a plasma flat gun (PFG).

[0039] The ion beam receiving section 2 includes a target substrate holding section 21 and a mask set holding section 22.

[0040] The target substrate holding unit 21 is positioned in the path of the ion beam IB and is capable of holding the target substrate 100 that is irradiated by the ion beam IB.

[0041] The mask set holding unit 22 is positioned in the path of the ion beam IB, prior to the target substrate 100 held by the target substrate holding unit 21, and can hold multiple masks that can selectively pass through the ion beam IB. The mask set holding unit 22 includes, for example, a mask holding unit 22A and a mask holding unit 22B. The number of masks is not particularly limited as long as it is two or more.

[0042] Next, an example of the configuration of the ion beam receiving section 2 will be described. Figures 15 and 16 are schematic diagrams showing an example of the configuration of the ion beam receiving section 2. The target substrate holding section 21, the mask holding section 22A, and the mask holding section 22B are composed of, for example, a holding device 20. Figure 15 is a schematic diagram of the side view of the holding device 20 (parallel to the direction of ion beam IB's propagation). Figure 16 is a schematic diagram of the front view of the holding device 20 (perpendicular to the direction of ion beam IB's propagation).

[0043] The holding device 20 includes a stage 23, a fixing device 24, a fixing device 25, a rotating mechanism 26, and a rotating mechanism 27.

[0044] Stage 23 has a mounting surface on which the target substrate 100 is placed. The mounting surface can be oriented between the vertical and horizontal directions. Stage 23 may have a picker capable of picking up the target substrate 100. An example of a picker is a vacuum chuck. Stage 23 can move the target substrate 100 along the vertical and horizontal directions. In the case of a horizontally elongated ion beam IB, Stage 23 may be scanned vertically. In the case of a vertically elongated ion beam IB, Stage 23 may be scanned horizontally. Stage 23 is also rotatable about a rotation axis CA that is aligned with the direction of travel of the ion beam IB and the center of the mounting surface. Stage 23 can constitute a target substrate holding section 21.

[0045] The fixing device 24 can fix the mask 201. The mask 201 is fixed, for example, by multiple fixing devices 24. The fixing device 24 is connected to a rotating mechanism 26 provided on the stage 23. The fixing device 24 and the rotating mechanism 26 constitute a mask holding section 22A, which can rotate the mask 201 about the rotation axis CA. The mask holding section 22A does not necessarily have a configuration that allows the mask 201 to rotate. The mask holding section 22A can move the mask 201 along the vertical and horizontal directions in conjunction with the target substrate 100.

[0046] The fixing device 25 can fix the mask 202. The mask 202 is fixed, for example, by multiple fixing devices 25. The fixing device 25 is connected to a rotating mechanism 27 provided on the stage 23. The fixing device 25 and the rotating mechanism 27 constitute a mask holding section 22B, which can rotate the mask 202 about a rotation axis CA. The mask holding section 22B does not necessarily have to have a configuration that allows the mask 202 to rotate. The mask holding section 22B can move the mask 202 along the vertical and horizontal directions in conjunction with the target substrate 100.

[0047] In Figures 15 and 16, the size of the target substrate 100 is shown to be smaller than the size of the mask 201, and the size of the mask 202 is shown to be smaller than the size of the mask 201. However, the sizes of the target substrate 100, mask 201, and mask 202 are not limited to these figures.

[0048] The operation of each component of the ion beam irradiation unit 1 and the ion beam receiving unit 2 may be controlled by a control device. The control device may be configured using hardware such as a processor. Alternatively, each operation may be stored as an operation program on a computer-readable recording medium such as memory, and each operation may be executed by appropriately reading the operation program stored on the recording medium using hardware.

[0049] Figure 17 is a schematic diagram showing an example of the structure of a mask set. The mask set includes mask 201 and mask 202. Figure 17 shows an example of the planar shape of mask 201 and an example of the planar shape of mask 202 as viewed from the direction of ion beam IB propagation.

[0050] The mask 201 is held by the mask holding portion 22A. The planar shape of the mask 201 is, for example, circular. The mask 201 has an aperture pattern 211 including an opening 211a and an opening 211b. The mask 201 can selectively block the ion beam IB and selectively allow it to pass through the aperture pattern 211.

[0051] The opening 211a preferably extends in a fan shape from the center C1 of the mask 201 toward the periphery of the mask 201. The center C1 may coincide with the center C or the rotation axis CA in the direction of propagation of the ion beam IB. Figure 17 shows a plurality of openings 211a, but the number of openings 211a is not particularly limited and may be one or more. One of the plurality of openings 211a may have a point symmetry relationship with respect to the center C1 as the point of symmetry.

[0052] The opening 211b is directly connected to the opening 211a and extends continuously from the opening 211a. Preferably, the opening 211b extends in a linear manner, passing through the center C1. Both ends of the opening 211b in the longitudinal direction may extend to the arc-shaped ends of the multiple openings 211a, so as to separate the multiple openings 211a.

[0053] The mask 202 is held by the mask holding portion 22B. The planar shape of the mask 202 is, for example, circular. The mask 202 has an aperture pattern 221 including an opening 221a and an opening 221b. The mask 202 can selectively block the ion beam and selectively allow it to pass through the aperture pattern 221.

[0054] The aperture 221a preferably extends in a fan shape from the center C2 of the mask 202 toward the periphery of the mask 202. The center C2 may coincide with the center C or the rotation axis CA in the direction of propagation of the ion beam IB. Figure 17 shows a plurality of apertures 221a, but the number of apertures 221a is not particularly limited and may be one or more. One of the plurality of apertures 221a may have a point-symmetric relationship with respect to the center C2 as the point of symmetry.

[0055] The opening 221b is directly connected to the opening 221a and extends continuously from the opening 221a. Preferably, the opening 221b extends in a linear manner, passing through the center C2. Both ends of the opening 221b in the longitudinal direction may extend to the arc-shaped ends of the multiple openings 221a, so as to separate the multiple openings 221a.

[0056] In masks 201 and 202, it is preferable that the planar shape of the opening pattern 211 and the planar shape of the opening pattern 221 are symmetrical. For example, it is preferable that the planar shape of the opening 211b and the planar shape of the opening 221b coincide when rotated 90 degrees around a rotation axis CA passing through centers C1 and C2.

[0057] The materials for masks 201 and 202 are not particularly limited, but may be graphite, for example. Masks 201 and 202 can be formed by processing a substrate such as a graphite plate to form a desired aperture pattern.

[0058] Figures 18 and 19 are schematic diagrams illustrating examples of ion implantation methods and semiconductor device manufacturing methods using masks 201 and 202. The X and Y axes represent, for example, the plane directions of the target substrate 100. The Z axis represents the thickness direction of the target substrate 100.

[0059] When forming a fan-shaped high-dose region 100A and a fan-shaped low-dose region 100B on the back surface of the target substrate 100, as shown in Figure 7, at least one of the masks 201 and 202 is rotated around the rotation axis CA so that, as shown in Figure 18, the openings 211a and 221a in the path of the ribbon-shaped ion beam IB overlap with the position on the target substrate 100 where the high-dose region 100A is to be formed, and the openings 211b and 221b are rotated 90 degrees relative to each other, and the ion beam IB is irradiated. The ion beam IB passes through the openings 211a and 221a and irradiates the back surface of the target substrate 100. On the other hand, at least a portion of the ion beam IB in the opening 211b is blocked by the mask 202, and at least a portion of the ion beam IB in the opening 221b is blocked by the mask 201. This makes it possible to form the high-dose region 100A and the low-dose region 100B on the back surface of the target substrate 100. The present invention is not limited to this, and a high-dose region 100A and a low-dose region 100B may be formed by irradiating the target substrate 100 with the ion beam IB while rotating at least one of the masks 201 and 202 so that the openings 211a and 221a overlap in the path of the ribbon-shaped ion beam IB at the position where a high-dose region 100A of the target substrate 100 is to be formed.

[0060] As shown in Figure 8, when forming a line-shaped high-dose region 100A on the back surface of the target substrate 100 so as to demarcate the low-dose region 100B, at least one of the masks 201 and 202 is rotated around the rotation axis CA so that, as shown in Figure 19, the openings 211b and 221b in the path of the ribbon-shaped ion beam IB overlap with the position on the target substrate 100 where the high-dose region 100A is to be formed, and the openings 211a and 221a are rotated 90 degrees, and the ion beam IB is irradiated. The irradiated ion beam IB passes through the openings 211b and 221b and irradiates the back surface of the target substrate 100. On the other hand, at least a portion of the ion beam IB in the opening 211a is blocked by the mask 202, and at least a portion of the ion beam IB in the opening 221a is blocked by the mask 201. This makes it possible to form a high-dose region 100A and a low-dose region 100B on the back surface of the target substrate 100. The method is not limited to this, but a high-dose region 100A and a low-dose region 100B may be formed by irradiating the target substrate 100 with the ion beam IB while rotating at least one of the masks 201 and 202 so that the apertures 211b and 221b overlap in the path of the ribbon-shaped ion beam IB at the position where a high-dose region 100A is to be formed on the target substrate 100.

[0061] In this embodiment, ion implantation is performed by selectively irradiating the back surface of the target substrate 100 with an ion beam IB via a mask set including mask 201 and mask 202. This eliminates the need for irradiation of a ribbon-shaped ion beam IB, which is 1 × 10⁻¹⁰. 15 / cm 2 Even when forming the high-dose region 100A described above, the high-dose region 100A can be selectively formed in a portion of the target substrate 100. Furthermore, by making the planar shapes of the opening patterns of mask 201 and mask 202 a combination of multiple openings with different planar shapes, and by making at least one mask rotatable, multiple high-dose regions 100A with different shapes can be formed on the back surface of the target substrate 100 using the same mask set. Thus, the versatility of the ion implantation apparatus can be increased.

[0062] Figures 20 and 21 are schematic diagrams showing modified versions of the mask set. Figures 20 and 21 show modified planar shapes of mask 201 and mask 202.

[0063] When the planar shape of openings 211a and 221a is fan-shaped, the central angles of openings 211a and 221a can be changed as appropriate, as shown in Figure 20, but are preferably 90 degrees or less. By keeping the angles at 90 degrees or less, a high dose region 100A as shown in Figure 7 can be easily formed.

[0064] If the planar shape of openings 211b and 221b is linear, the widths of openings 211a and 221a can be changed as appropriate, as shown in Figure 21. The widths of openings 211a and 221a are, for example, the length in the direction perpendicular to the length direction (long axis direction) of openings 211a and 221a (short axis direction).

[0065] Figures 22 and 23 are schematic diagrams illustrating an example of a method for transporting the target substrate 100 after ion implantation. The X and Y axes represent, for example, the planar directions of the target substrate 100. The Z axis represents the thickness direction of the target substrate 100.

[0066] The target substrate 100 can be loaded and unloaded using, for example, a transport arm 30 provided inside or outside the ion implantation apparatus. During loading and unloading, the mounting surface of the stage 23 is oriented vertically. After ion implantation, it is preferable that the target substrate 100 is unloaded after at least one of the masks 201 and 202 is rotated using at least one of the mask holding parts 22A and 22B, and then the fixing devices 24 and 25 are returned to their initial positions so that they are aligned in a straight line, as shown in Figure 22. As shown in Figure 23, if the fixing devices 24 and 25 are not aligned in a straight line, the transport arm 30 and the fixing device 24 or 25 may interfere with each other, hindering the unloading of the target substrate 100.

[0067] 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 novel 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 of the invention and its equivalents. [Explanation of Symbols]

[0068] 1...Ion beam irradiation unit, 2...Ion beam receiving unit, 11...Ion source, 12...Drawer electrode, 13...Analyzer magnet, 14...Mass slit, 15...Collector magnet, 16...Electron neutralizer, 20...Holding device, 21...Target substrate holding unit, 22...Mask set holding unit, 22A...Mask holding unit, 22B...Mask holding unit, 23...Stage, 24...Fixing device, 25...Fixing device, 26...Rotation mechanism, 27...Rotation mechanism, 30...Transport arm, 100...Target substrate, 100A...High dose area Region, 100B...Low dose region, 101...Semiconductor substrate, 102...Semiconductor substrate, 111...Semiconductor wafer, 111a...Surface, 111b...Surface, 112...Layer, 121...Semiconductor wafer, 121a...Surface, 121b...Surface, 122...Layer, 201...Mask, 202...Mask, 211...Aperture pattern, 211a...Aperture, 211b...Aperture, 221...Aperture pattern, 221a...Aperture, 221b...Aperture, C...Center, C1...Center, C2...Center, CA...Rotation axis, IB...Ion beam.

Claims

1. An ion beam irradiation unit that irradiates with a ribbon-shaped ion beam, A target substrate holding unit capable of holding a target substrate placed in the path of the ion beam, A first mask holding unit capable of holding a first mask, which is positioned in front of the target substrate in the aforementioned path, A second mask holding unit capable of holding a second mask positioned between the first mask and the target substrate in the aforementioned path, It is equipped with, The first mask has a first aperture pattern through which the ion beam can pass, The second mask has a second aperture pattern through which the ion beam can pass. Ion implantation device.

2. The first opening pattern and the second opening pattern have different planar shapes. At least one mask holder selected from the group consisting of the first mask holder and the second mask holder is capable of rotating at least one mask selected from the group consisting of the first mask and the second mask about a rotation axis along the direction of propagation of the ion beam. The ion implantation apparatus according to claim 1.

3. The first opening pattern includes a first opening that extends in a fan shape from the center of the first mask toward the periphery, and a second opening that extends in a line shape passing through the center of the first mask. The second opening pattern includes a third opening that extends in a fan shape from the center of the second mask toward the periphery, and a fourth opening that extends in a line shape passing through the center of the second mask. The ion implantation apparatus according to claim 1.

4. The first opening pattern has a plurality of the first openings, The second opening pattern has a plurality of the third openings, The ion implantation apparatus according to claim 3.

5. The central angle of the first opening is 90 degrees or less. The central angle of the third opening is 90 degrees or less. The planar shape of the first opening pattern and the planar shape of the second opening pattern are symmetrical. The ion implantation apparatus according to claim 3.

6. The ion beam contains at least one ion selected from the group consisting of arsenic ions, germanium ions, argon ions, boron fluoride ions, nitrogen ions, carbon ions, and boron ions. The ion implantation apparatus according to claim 1.

7. The aforementioned target substrate is A semiconductor wafer having a first surface and a second surface opposite to the first surface, The layer formed on the first surface, It has, The ion beam is irradiated onto the second surface through the first mask and the second mask. The ion implantation apparatus according to claim 1.

8. A mask set placed in front of a target substrate arranged in the path of a ribbon-shaped ion beam, A first mask having a first opening pattern, A second mask having a second opening pattern, It is equipped with, The first opening pattern is, A first opening extending in a fan shape from the center to the periphery of the first mask, A second opening extending in a linear manner through the center of the first mask, Includes, The second opening pattern is, A third opening extending in a fan shape from the center to the periphery of the second mask, A fourth opening extending linearly through the center of the second mask, Includes, The planar shape of the first opening pattern and the planar shape of the second opening pattern are symmetrical. Mask set.

9. A target substrate, including a semiconductor wafer having a first surface and a second surface opposite to the first surface, and a layer formed on the first surface, is placed in the path of a ribbon-shaped ion beam, a first mask having a first aperture pattern is placed in front of the target substrate in the path, and a second mask having a second aperture pattern is placed between the first mask and the target substrate in the path. The first opening pattern is, A first opening extending in a fan shape from the center to the periphery of the first mask, A second opening extending in a linear manner through the center of the first mask, Includes, The second opening pattern is, A third opening extending in a fan shape from the center to the periphery of the second mask, A fourth opening extending linearly through the center of the second mask, Includes, The planar shape of the first opening pattern and the planar shape of the second opening pattern are symmetrical. At least one mask selected from the group consisting of the first mask and the second mask is rotated about a rotation axis along the direction of propagation of the ion beam, and the ion beam is selectively irradiated onto the second surface via the first mask and the second mask, thereby forming a dose distribution of ions contained in the ion beam on the semiconductor wafer. A method for manufacturing a semiconductor device.

10. By selectively irradiating the second surface with the ion beam, A first region extending in a first direction passing through the center of the second surface and having a first dose of the ions, A second region that passes through the center of the second surface and extends in a second direction perpendicular to the first direction, and has a second dose amount of the ion that is higher than the first dose amount, To form on the second surface, The method for manufacturing a semiconductor device according to claim 9.

11. The second region extends in a fan shape from the center of the second surface toward the periphery of the second surface. A method for manufacturing a semiconductor device according to claim 10.

12. The second region extends in a line that passes through the center of the second surface. A method for manufacturing a semiconductor device according to claim 10.

Images