JP2017175145A - Semiconductor epitaxial wafer manufacturing method, semiconductor epitaxial wafer, and solid-state imaging element manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor epitaxial wafer manufacturing method capable of inhibiting metallic contamination by utilizing higher gettering capability.SOLUTION: A manufacturing method of a semiconductor epitaxial wafer 100 comprises: a first step of irradiating a surface 10A of a semiconductor wafer 10 with first cluster ions 16 and a rear face 10B thereof with second cluster ions 17 to form a first modifying layer 18 composed of a constituent element of the first cluster ion 16 on the surface 10A of the semiconductor wafer 10 and a second modifying layer 19 composed of a constituent element of the second cluster ion 17 on the rear face 10B of the semiconductor wafer 10; and a second step of forming an epitaxial layer 20 on the first modifying layer 18 of the semiconductor wafer 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a semiconductor epitaxial wafer, a semiconductor epitaxial wafer, and a method for manufacturing a solid-state imaging device. In particular, the present invention relates to a semiconductor epitaxial wafer capable of suppressing metal contamination by exhibiting higher gettering ability and a method for manufacturing the same.

  Metal contamination is a factor that degrades the characteristics of semiconductor devices. For example, in a back-illuminated solid-state imaging device, metal mixed in a semiconductor epitaxial wafer serving as the substrate of this device causes a dark current of the solid-state imaging device to increase and causes a defect called a white defect. The back-illuminated solid-state image sensor has a wiring layer, etc., placed below the sensor part, so that external light can be taken directly into the sensor and clearer images and videos can be taken even in dark places. In recent years, it has been widely used in mobile phones such as digital video cameras and smartphones. Therefore, it is desired to reduce white defect as much as possible.

  Metal contamination in the wafer occurs mainly in the manufacturing process of the semiconductor epitaxial wafer and the manufacturing process (device manufacturing process) of the solid-state imaging device. Metal contamination in the former semiconductor epitaxial wafer manufacturing process is caused by heavy metal particles from the components of the epitaxial growth furnace, or because the chlorine gas is used as the furnace gas during epitaxial growth, the piping material is corroded by metal. The thing by the heavy metal particle to generate | occur | produce is considered. In recent years, these metal contaminations have been improved to some extent by replacing the constituent materials of the epitaxial growth furnace with materials having excellent corrosion resistance, but are not sufficient. On the other hand, in the latter manufacturing process of the solid-state imaging device, there is a concern about heavy metal contamination of the semiconductor substrate during each process such as ion implantation, diffusion and oxidation heat treatment.

  Therefore, conventionally, a gettering sink for capturing a metal is formed on a semiconductor epitaxial wafer, or a substrate having a high metal capture capability (gettering capability) such as a high-concentration boron substrate is used. The metal contamination was avoided.

  As a method of forming a gettering sink in a semiconductor wafer, oxygen precipitates (commonly referred to as silicon oxide precipitates, also referred to as BMD: Bulk Micro Defect) and dislocations are formed inside the semiconductor wafer. An intrinsic gettering (IG) method and an extrinsic gettering (EG) method in which a gettering sink is formed on the back surface of a semiconductor wafer are generally used.

  Here, as one method of the heavy metal gettering method, there is a technique of forming a gettering site in a semiconductor wafer by ion implantation. Patent Document 1 describes a manufacturing method in which carbon ions are implanted from one surface of a silicon wafer to form a carbon ion implanted region, and then a silicon epitaxial layer is formed on this surface to form a silicon epitaxial wafer. In this technique, the carbon ion implantation region functions as a gettering site.

  In Patent Document 2, carbon ions are implanted into a silicon wafer to form a carbon implanted layer, and then heat treatment for recovering the crystallinity of the wafer disturbed by the ion implantation is performed with an RTA (Rapid Thermal Annealing) apparatus. A technique for shortening the recovery heat treatment process by performing the process is described.

  Further, Patent Document 3 discloses that a back surface of a silicon wafer opposite to a surface on which a plurality of devices are formed is irradiated with inert gaseous substance cluster ions or nitrogen gas cluster ions, and gettering is performed on the back surface of the silicon wafer. Techniques for applying layers are described.

JP-A-6-338507 JP 2008-294245 A JP 2011-253983 A

  The techniques described in Patent Document 1 and Patent Document 2 both inject monomer ions (single ions) into a semiconductor wafer before forming an epitaxial layer. However, according to the study by the present inventors, it has been found that a semiconductor epitaxial wafer subjected to monomer ion implantation has insufficient gettering capability and a stronger gettering capability is required.

  Moreover, the technique described in Patent Document 3 irradiates the back surface of the semiconductor wafer with cluster ions, and there is no description of forming an epitaxial layer on the front surface of the semiconductor wafer after the cluster ion irradiation. That is, Patent Document 3 is not intended for proximity gettering in which a gettering layer is provided immediately below an epitaxial layer of a semiconductor epitaxial wafer.

  In view of the above problems, the present invention provides a semiconductor epitaxial wafer capable of suppressing metal contamination by exhibiting higher gettering capability, a method for manufacturing the same, and a solid-state imaging device formed from the semiconductor epitaxial wafer. It aims at providing the manufacturing method of a solid-state image sensor.

  Hereinafter, in this specification, the surface of the semiconductor wafer on which the epitaxial layer is not formed is referred to as “the back surface of the semiconductor wafer” or simply “the back surface”, and the surface on which the epitaxial layer is formed is referred to as “the front surface of the semiconductor wafer” "Surface" or simply "front surface", and both surfaces are collectively referred to as "front and back surfaces".

  According to further studies by the present inventors, by irradiating cluster ions on the front and back surfaces of the semiconductor wafer, the following advantages are obtained compared with the case where monomer ions are implanted into the front surface of the semiconductor wafer. I found out that there was. That is, when irradiating with cluster ions, even if irradiation is performed at an acceleration voltage equivalent to that of monomer ions, the energy per atom or molecule is lower than that of monomer ions, and a plurality of atoms are irradiated at one time. Since it collides with the wafer, the peak concentration can be made high in the concentration profile in the depth direction of the irradiated element, and the peak position can be located closer to the front and back surfaces of the semiconductor wafer. As a result, it has been found that the gettering ability of the front and back surfaces of the semiconductor epitaxial wafer is improved even after the epitaxial layer is formed.

Based on the above findings, the present inventors have completed the present invention.
That is, in the method for producing a semiconductor epitaxial wafer of the present invention, the front surface of the semiconductor wafer is irradiated with the first cluster ions and the back surface is irradiated with the second cluster ions, and the front surface of the semiconductor wafer is irradiated with the first cluster ions. A first step of forming a first modified layer comprising a constituent element of one cluster ion and forming a second modified layer comprising a constituent element of the second cluster ion on the back surface of the semiconductor wafer; and the semiconductor wafer And a second step of forming an epitaxial layer on the first modified layer.

  Here, the semiconductor wafer may be a silicon wafer.

  The peak concentration of the dopant element in the semiconductor wafer is preferably higher than the peak concentration of the dopant element in the epitaxial layer.

  The semiconductor wafer may be an epitaxial silicon wafer in which a silicon epitaxial layer is formed on the front surface of a silicon wafer. In this case, in the first step, the first modified layer is a portion of the silicon epitaxial layer. The second modified layer is formed on the back surface of the silicon wafer.

  In the present invention, after the first step, the second step can be performed by transferring the semiconductor wafer to an epitaxial growth apparatus without performing a heat treatment for recovering crystallinity on the semiconductor wafer. However, it is also preferable to perform heat treatment for crystallinity recovery on the semiconductor wafer after the first step and before the second step.

  Here, it is preferable that the first and / or second cluster ions include carbon as a constituent element.

  In this case, the first and / or second cluster ions further include a dopant element as a constituent element, and the dopant element is one or more elements selected from the group consisting of boron, phosphorus, arsenic, and antimony. More preferably.

Furthermore, the irradiation conditions of the first cluster ions are that the acceleration voltage per carbon atom is 50 keV / atom or less, the cluster size is 100 or less, and the carbon dose is 5.0 × 10 ¹⁵ atoms / cm ² or less. Preferably, the irradiation conditions of the second cluster ions are as follows: an acceleration voltage per carbon atom is 50 keV / atom or less, a cluster size is 100 or less, and a carbon dose is 1.0 × 10 ¹⁴ atoms / cm ^2. The above is preferable.

  Next, a semiconductor epitaxial wafer of the present invention includes a semiconductor wafer, a first modified layer formed on the front surface of the semiconductor wafer, in which a predetermined element is dissolved in the semiconductor wafer, and the semiconductor A second modified layer formed on the back surface of the wafer, in which a predetermined element is dissolved in the semiconductor wafer, and an epitaxial layer on the first modified layer, the first modified layer The half width of the concentration profile in the depth direction of the predetermined element in the second modified layer is both 100 nm or less.

  Here, the semiconductor wafer may be a silicon wafer.

  The peak concentration of the dopant element in the semiconductor wafer is preferably higher than the peak concentration of the dopant element in the epitaxial layer.

  The semiconductor wafer may be an epitaxial silicon wafer in which a silicon epitaxial layer is formed on the front surface of a silicon wafer. In this case, the first modified layer is positioned on the front surface of the silicon epitaxial layer. The second modified layer is located on the back surface of the silicon wafer.

  The peak of the concentration profile in the first modified layer is located within a depth of 150 nm or less from the front surface of the semiconductor wafer, and the depth from the back surface of the semiconductor wafer is 150 nm or less. It is preferable that the peak of the concentration profile in the second modified layer is located within the range.

Additionally, the peak concentration of the concentration profile in the first reforming layer has a 1 × ¹⁰ 15 atoms / cm ³ or more, the peak concentration of the concentration profile in the second modified layer, 1 × ¹⁰ 15 atoms / It is preferable that it is cm ³ or more.

  Here, it is preferable that the predetermined element dissolved in the first and / or second modified layer contains carbon.

  In this case, it is preferable that the predetermined element further includes a dopant element, and the dopant element is one or more elements selected from the group consisting of boron, phosphorus, arsenic, and antimony.

  And the manufacturing method of the solid-state image sensor of this invention is the solid-state image sensor on the epitaxial layer located in the front surface of the epitaxial wafer manufactured by the said any one manufacturing method, or the said any one epitaxial wafer. It is characterized by forming.

  According to the method for manufacturing a semiconductor wafer of the present invention, the first cluster ion is irradiated to the front surface of the semiconductor wafer and the second cluster ion is irradiated to the back surface, and the first cluster is applied to the front surface of the semiconductor wafer. Since the first modified layer made of the constituent element of ions is formed and the second modified layer made of the constituent element of the second cluster ions is formed on the back surface of the semiconductor wafer, the first modified layer and the second modified layer are formed. Since the modified layer exhibits higher gettering capability, a semiconductor epitaxial wafer capable of suppressing metal contamination can be manufactured, and a high-quality solid-state imaging device is manufactured from the semiconductor epitaxial wafer. be able to.

1 is a schematic cross-sectional view illustrating a method for manufacturing a semiconductor epitaxial wafer 100 according to an embodiment of the present invention. It is a model cross section explaining the manufacturing method of the semiconductor epitaxial wafer 200 by other embodiment of this invention. (A) is a schematic diagram explaining the irradiation mechanism in the case of irradiating cluster ions, (B) is a schematic diagram explaining the injection mechanism in the case of injecting monomer ions. It is a carbon concentration profile obtained by SIMS measurement in Reference Examples 1 and 2. It is the density | concentration profile of the carbon obtained by the SIMS measurement in Example 1 which irradiated the cluster ion, (A) shows the front surface side, (B) shows the back surface side. It is the density | concentration profile of the carbon obtained by the SIMS measurement in the comparative example 1 which inject | poured the monomer ion.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In principle, the same components are denoted by the same reference numerals, and description thereof is omitted. 1 and 2 exaggerate the thicknesses of the first and second epitaxial layers 14 and 20 with respect to the semiconductor wafer 10 for convenience of explanation, unlike the actual thickness ratio.

(Method of manufacturing semiconductor epitaxial wafer)
A method for manufacturing a semiconductor epitaxial wafer 100 according to the first embodiment of the present invention is shown in FIG. In the method for manufacturing a semiconductor epitaxial wafer of the present invention, first, as a first step, the front surface 10A of the semiconductor wafer 10 is irradiated with the first cluster ions 16, and the front surface 10A of the semiconductor wafer 10 is irradiated with this first surface. A first modified layer 18 composed of the constituent elements of the cluster ions 16 is formed (FIGS. 1A and 1B), and the back surface 10B of the semiconductor wafer 10 is irradiated with the second cluster ions 17 to thereby form the semiconductor wafer 10. A second modified layer 19 made of the constituent elements of the cluster ions 17 is formed on the back surface 10B of the substrate (FIGS. 1C and 1D). Next, as a second step, an epitaxial layer 20 is formed on the first modified layer 18 of the semiconductor wafer 10 (FIG. 1F). FIG. 1F is a schematic cross-sectional view of a semiconductor epitaxial wafer 100 obtained as a result of this manufacturing method. The second modified layer 19 may be formed before the first modified layer 18 is formed, and the order of formation is not limited. The first step is intended to improve the gettering ability of the semiconductor epitaxial wafer 100 by forming the first modified layer 18 and the second modified layer 19. In the present specification, for convenience of explanation, it will be described hereinafter that the second modified layer 19 is formed after the first modified layer 18 is formed.

  Examples of the semiconductor wafer 10 include a bulk single crystal wafer made of silicon, a compound semiconductor (GaAs, GaN, SiC) and having no epitaxial layer on the front surface, and a back-illuminated solid-state imaging device is manufactured. In general, a bulk single crystal silicon wafer is used. Moreover, the semiconductor wafer 10 can use what sliced the single crystal silicon ingot grown by the Czochralski method (CZ method) and the floating zone melting method (FZ method) with the wire saw etc. In order to obtain a higher gettering capability, carbon and / or nitrogen may be added to the semiconductor wafer 10.

Furthermore, a predetermined concentration of an arbitrary dopant may be added to the semiconductor wafer 10 to form a so-called n + type or p + type, or n− type or p− type substrate. In the present embodiment, it is preferable to use the semiconductor wafer 10 in which the peak concentration of the dopant element in the semiconductor wafer 10 is higher than the peak concentration of the dopant element in the epitaxial layer 20. For example, it is preferable to use a p + substrate in which boron is doped at a high concentration of 1.0 × 10 ^{18 to} 1.0 × 10 ²⁰ atoms / cm ³ . This is because not only the first and second modified layers 18 and 19 but also the gettering ability of the semiconductor wafer 10 (p + substrate) itself is added, and higher gettering ability can be obtained. In this case, it is also preferable to form an oxide film on the back surface of the p + substrate to prevent autodoping.

  The first embodiment shown in FIG. 1 is an example in which a bulk semiconductor wafer 12 having no epitaxial layer on the front surface 10 </ b> A is used as the semiconductor wafer 10.

  Further, as the semiconductor wafer 10, as shown in FIG. 2A, an epitaxial semiconductor wafer in which a semiconductor epitaxial layer (first epitaxial layer) 14 is formed on the surface of the bulk semiconductor wafer 12 can be exemplified. For example, an epitaxial silicon wafer in which a silicon epitaxial layer is formed on the surface of a bulk single crystal silicon wafer. The silicon epitaxial layer can be formed under general conditions by a CVD method. The first epitaxial layer 14 preferably has a thickness in the range of 0.1 to 10 μm, and more preferably in the range of 0.2 to 5 μm.

  As an example of this, in the method of manufacturing a semiconductor epitaxial wafer 200 according to the second embodiment of the present invention, as shown in FIG. 2, first, as a first step, the first epitaxial layer 14 is formed on the surface (at least one side) of the bulk semiconductor wafer 12. The front surface 10A of the semiconductor wafer 10 formed with the first cluster ions 16 is irradiated to the front surface 10A of the semiconductor wafer (in this embodiment, the front surface 10A of the first epitaxial layer 14). The first modified layer 18 made of the constituent elements of the first cluster ions 16 is formed, and the second modified layer 19 made of the constituent elements of the second cluster ions 17 is formed on the back surface 10B of the semiconductor wafer (FIG. 2). (A) to (E)). Next, as a second step, a second epitaxial layer 20 is formed on the modified layer 18 of the semiconductor wafer 10 (FIG. 2G). FIG. 2G is a schematic cross-sectional view of a semiconductor epitaxial wafer 200 obtained as a result of this manufacturing method.

  Here, the characteristic steps of the present invention are as follows. First cluster ions 16 are provided on the front surface 10A of the semiconductor wafer as shown in FIGS. 1 (A) to (D) and FIGS. 2 (B) to (E). This is the first step of forming the first modified layer 18 and the second modified layer 19 by irradiating the second cluster ions 17 to 10B.

  The technical significance of adopting the first step will be described together with the effects. The first modified layer 18 formed as a result of the irradiation of the first cluster ions 16 is locally formed by the constituent elements of the first cluster ions 16 being dissolved in the interstitial positions or substitution positions of the crystal on the surface of the semiconductor wafer 10. It is an area that exists as a gettering site. Similarly, the second modified layer 19 formed as a result of the irradiation with the second cluster ions 17 also functions as a gettering site. The reason is presumed as follows. That is, elements such as carbon and boron irradiated in the form of cluster ions are localized at a high density in the substitution position / interstitial position of the silicon single crystal. It was experimentally confirmed that the solid solubility of heavy metals (saturated solubility of transition metals) greatly increases when carbon or boron is dissolved to an equilibrium concentration higher than that of the silicon single crystal. In other words, it is considered that the solid solubility of heavy metals is increased by carbon and boron dissolved to an equilibrium concentration or higher, and the capture rate for heavy metals is thereby remarkably increased.

  Here, in the present invention, since the first cluster ions 16 and the second cluster ions 17 are irradiated, higher gettering ability can be obtained as compared with the case where monomer ions are implanted, and further, the recovery heat treatment is omitted. be able to. Therefore, it becomes possible to manufacture the semiconductor epitaxial wafers 100 and 200 having higher gettering ability on the front and back surfaces, and the back-illuminated solid-state imaging device manufactured from the semiconductor epitaxial wafers 100 and 200 obtained by this manufacturing method is conventionally known. Compared to the above, it can be expected that white defect defects are suppressed.

  In the present specification, the “cluster ion” means an ionized product in which a plurality of atoms or molecules are aggregated to give a cluster having a lump to give a positive charge or a negative charge. A cluster is a massive group in which a plurality (usually about 2 to 2000) of atoms or molecules are bonded to each other.

  The present inventors consider the action of obtaining high gettering ability by irradiating cluster ions as follows.

  For example, when carbon monomer ions are implanted into a silicon wafer, as shown in FIG. 3B, the monomer ions are blown off silicon atoms constituting the silicon wafer and implanted at a predetermined depth in the silicon wafer. The The implantation depth depends on the type of constituent elements of the implanted ions and the acceleration voltage of the ions. In this case, the concentration profile of carbon in the depth direction of the silicon wafer is relatively broad, and the region where the implanted carbon is present is approximately 0.5 to 1 μm. When multiple types of ions are simultaneously irradiated with the same energy, lighter elements are implanted deeper, that is, implanted at different positions according to the mass of each element, so the concentration profile of the implanted elements becomes broader. . In the present specification, the “depth direction” means the depth direction on the front surface side means the direction from the front surface to the back surface of the semiconductor wafer, and the depth direction on the back surface side means the semiconductor wafer. It means the direction from the back to the front.

  Furthermore, the monomer ions are generally implanted at an acceleration voltage of about 150 to 2000 keV. Since each ion collides with a silicon atom with its energy, the crystallinity of the surface portion of the silicon wafer into which the monomer ions are implanted is disturbed. The crystallinity of the epitaxial layer grown on the wafer surface is disturbed. Also, the higher the acceleration voltage, the more the crystallinity is disturbed. Therefore, it is necessary to perform heat treatment (recovery heat treatment) for recovering disordered crystallinity after ion implantation at a high temperature for a long time.

  On the other hand, when the silicon wafer is irradiated with cluster ions made of, for example, carbon and boron, as shown in FIG. 3A, the first cluster ions 16 are instantaneously 1350 with the energy when irradiated to the silicon wafer. It becomes a high temperature state of about ˜1400 ° C., and silicon melts. Thereafter, the silicon is rapidly cooled, and carbon and boron are dissolved in the vicinity of the surface in the silicon wafer. Although FIG. 3A shows the first cluster ions 16 irradiated on the front surface 10A of the semiconductor wafer, the same phenomenon occurs also in the second cluster ions 17 irradiated on the back surface. That is, the “modified layer” in the present specification means a layer in which constituent elements of ions to be irradiated are dissolved in crystal interstitial positions or substitution positions on the surface of the semiconductor wafer. The concentration profile of carbon and boron in the depth direction of the silicon wafer depends on the acceleration voltage and cluster size of cluster ions, but is sharper than that of monomer ions, and the irradiated carbon and boron exist locally. The thickness of the region (that is, the modified layer) is approximately 500 nm or less (for example, about 50 to 400 nm). Note that the elements irradiated in the form of cluster ions undergo some thermal diffusion during the formation process of the epitaxial layer 20. Therefore, in the concentration profile of carbon and boron after the formation of the epitaxial layer 20, broad diffusion regions are formed on both sides of the peak where these elements are present locally. However, the thickness of the modified layer does not change greatly (see FIG. 5A described later). As a result, the carbon and boron precipitation regions can be locally and highly concentrated. Further, since the modified layer is formed near the surface of the silicon wafer, closer gettering is possible. As a result, it is considered that higher gettering ability can be obtained. In the case of the cluster ion form, there is an advantage that a plurality of types of ions can be irradiated simultaneously by a single cluster ion irradiation treatment.

  The cluster ions 16 are generally irradiated at an acceleration voltage of about 10 to 100 keV / Cluster. However, since the cluster is an aggregate of a plurality of atoms or molecules, it is implanted with a small energy per atom or molecule. Therefore, the damage to the crystal of the silicon wafer is small. Furthermore, due to the difference in the implantation mechanism as described above, the cluster ion irradiation does not disturb the crystallinity of the silicon wafer 10 more than the monomer ion implantation. Therefore, after the first step, the silicon wafer 10 can be transferred to the epitaxial growth apparatus and the second step can be performed without performing a recovery heat treatment on the silicon wafer 10 (FIGS. 1E and 2F). )).

  The cluster ion has various clusters depending on the binding mode, and can be generated by a known method as described in, for example, the following documents. As a method for generating a gas cluster beam, (1) JP-A-9-41138, (2) JP-A-4-354865, and as an ion beam generation method, (1) charged particle beam engineering: Junzo Ishikawa: ISBN978 -4-339-00734-3: Corona, (2) Electron / ion beam engineering: The Institute of Electrical Engineers of Japan: ISBN4-88686-217-9: Ohm, (3) Cluster ion beam foundation and application: ISBN4-526-05765 -7: Nikkan Kogyo Shimbun. In general, a Nielsen ion source or a Kaufman ion source is used to generate positively charged cluster ions, and a large current negative ion source using a volume generation method is used to generate negatively charged cluster ions. It is done.

  Hereinafter, the irradiation conditions of the first cluster ions 16 and the second cluster ions 17 will be described. In addition, regarding irradiation conditions such as an irradiation element, cluster size, acceleration voltage, and dose described below, the irradiation conditions of the first cluster ions 16 and the irradiation conditions of the second cluster ions 17 are the same or different. Also good.

  Although the kind of irradiation element is not particularly limited, it is preferable that the first and / or second cluster ions contain carbon as a constituent element from the viewpoint of obtaining higher gettering ability. Since the carbon atom at the lattice position has a smaller covalent bond radius than that of the silicon single crystal, a contraction field of the silicon crystal lattice is formed, so that the gettering ability to attract impurities between the lattices is high.

  The irradiation element preferably further contains a dopant element in addition to carbon, and the dopant element as the irradiation element is preferably one or more elements selected from the group consisting of boron, phosphorus, arsenic and antimony. . This is because the types of metals that can be efficiently gettered differ depending on the types of deposited elements, so that two or more types of elements can be dissolved to cope with a wider range of metal contamination. For example, in the case of carbon, nickel can be efficiently gettered, and in the case of boron, copper and iron can be efficiently gettered.

The compound to be ionized is not particularly limited, but ethane, methane, carbon dioxide (CO ₂ ), or the like can be used as the ionizable carbon source compound, and diborane, decaborane ( B ₁₀ H ₁₄ ) or the like can be used. For example, when a gas in which benzyl and decaborane are mixed is used as a material gas, a hydrogen compound cluster in which carbon, boron, and hydrogen are aggregated can be generated. If cyclohexane (C ₆ H ₁₂ ) is used as a material gas, cluster ions composed of carbon and hydrogen can be generated. As the carbon source compound, it is particularly preferable to use a cluster C _n H _m (3 ≦ n ≦ 16, 3 ≦ m ≦ 10) formed from pyrene (C ₁₆ H ₁₀ ), dibenzyl (C ₁₄ H ₁₄ ) or the like. This is because it is easy to control a small-sized cluster ion beam.

  As the compound to be ionized, a compound containing both carbon and the above dopant element is also preferable. This is because if such a compound is irradiated as cluster ions, both carbon and the dopant element can be dissolved in a single irradiation.

  Further, by controlling the acceleration voltage and the cluster size of the first and / or second cluster ions, the position of the peak of the concentration profile in the depth direction of the constituent elements in the first modified layer 18 and the second modified layer 19 is controlled. Can be controlled. In this specification, “cluster size” means the number of atoms or molecules constituting one cluster.

  In the first step of this embodiment, from the viewpoint of obtaining high gettering capability, the depth of the constituent elements in the first modified layer 18 is within the range where the depth from the front surface 10A of the semiconductor wafer 10 is 150 nm or less. The first cluster ions 16 are irradiated so that the peak of the concentration profile in the vertical direction is located, and the depth in the depth direction of the constituent elements in the second modified layer 19 is within the range of 150 nm or less from the back surface 10B. The second cluster ions 17 are irradiated so that the peak of the concentration profile is located. In the present specification, “concentration profile of constituent elements in the depth direction” means not a total of constituent elements but a profile of each individual element.

When C _n H _m (3 ≦ n ≦ 16, 3 ≦ m ≦ 10) is used as the first cluster ion as a necessary condition for setting the peak position within the range of the depth, acceleration per carbon atom The voltage is more than 0 keV / atom and 50 keV / atom or less, preferably 40 keV / atom or less. The cluster size is 2 to 100, preferably 60 or less, more preferably 50 or less. In addition, when C _n H _m (3 ≦ n ≦ 16, 3 ≦ m ≦ 10) is used as the second cluster ion, the acceleration voltage per carbon atom is more than 0 keV / atom and 50 keV / atom or less, preferably 40 keV / atom or less is desirable. The cluster size is 2 to 100, preferably 60 or less, more preferably 50 or less.

  For adjusting the acceleration voltage, two methods of (1) electrostatic acceleration and (2) high frequency acceleration are generally used. As the former method, there is a method in which a plurality of electrodes are arranged at equal intervals and an equal voltage is applied between them to create an equal acceleration electric field in the axial direction. As the latter method, there is a linear linac method in which ions are accelerated using a high frequency while running linearly. The cluster size can be adjusted by adjusting the gas pressure of the gas ejected from the nozzle, the pressure of the vacuum vessel, the voltage / current value applied to the filament when ionizing, and the like. The cluster size can be obtained by obtaining a cluster number distribution by mass spectrometry using a quadrupole high-frequency electric field or time-of-flight mass spectrometry and taking an average value of the number of clusters.

Moreover, the dose amount of cluster ions can be adjusted by controlling the ion irradiation time. In this embodiment, the carbon dose of the first cluster ions 16 is 1 × 10 ¹³ to 1 × 10 ¹⁶ atoms / cm ² , preferably 5 × 10 ¹⁵ atoms / cm ² or less. If it is less than 1 × 10 ¹³ atoms / cm ² , the gettering ability may not be sufficiently obtained. If it exceeds 1 × 10 ¹⁶ atoms / cm ² , the front surface of the epitaxial layer 20 will be significantly damaged. It is because there is a possibility of giving. Further, the carbon dose of the second cluster ions 17 is set to 1 × 10 ¹³ to 1 × 10 ¹⁶ atoms / cm ² , but because the irradiation is performed on the back surface of the semiconductor wafer, even if the damage to the back surface is somewhat increased. Since the quality of the epitaxial layer 20 is not affected, it is preferably 1.0 × 10 ¹⁴ atoms / cm ² or more from the viewpoint of providing higher gettering ability.

  According to the present invention, as described above, there is no need to perform the recovery heat treatment using a rapid heating / cooling heat treatment device such as RTA or RTO that is separate from the epitaxial device. This is because the crystallinity of the silicon wafer 10 can be sufficiently recovered by a hydrogen baking process prior to epitaxial growth in an epitaxial apparatus for forming the epitaxial silicon layer 20 described below. The general conditions for the hydrogen baking are as follows: the inside of the epitaxial growth apparatus is in a hydrogen atmosphere, the silicon wafer 10 is placed in the furnace at a furnace temperature of 600 ° C. or higher and 900 ° C. or lower, and 1 ° C./second or higher and 15 ° C./second or lower. The temperature is raised to a temperature range of 1100 ° C. or higher and 1200 ° C. or lower at a temperature rising rate, and the temperature is maintained for 30 seconds or longer and 1 minute or shorter. This hydrogen baking process is originally intended to remove the natural oxide film formed on the wafer surface by the cleaning process before the epitaxial layer growth, but the crystallinity of the silicon wafer 10 is sufficiently restored by the hydrogen baking under the above conditions. Can be made.

  Needless to say, recovery heat treatment may be performed after the first step and before the second step by using a heat treatment apparatus separate from the epitaxial apparatus (FIGS. 1E and 2F). This recovery heat treatment may be performed at 900 ° C. to 1200 ° C. for 10 seconds to 1 hour. Here, the reason why the heat treatment temperature is set to 900 ° C. or more and 1200 ° C. or less is that if the temperature is less than 900 ° C., it is difficult to obtain the crystallinity recovery effect. This is because slip occurs and the heat load on the apparatus increases. Moreover, the heat treatment time is set to 10 seconds or more and 1 hour or less because a recovery effect is difficult to be obtained if the heat treatment time is less than 10 seconds. This is because it becomes larger.

  Such recovery heat treatment can be performed using, for example, a rapid heating / cooling heat treatment apparatus such as RTA or RTO, or a batch heat treatment apparatus (vertical heat treatment apparatus, horizontal heat treatment apparatus). Since the former is a lamp irradiation heating method, it is not suitable for long-time treatment in terms of the device structure, and is suitable for heat treatment within 15 minutes. On the other hand, in the latter, although it takes time to raise the temperature to a predetermined temperature, a large number of wafers can be processed simultaneously. In addition, because of the resistance heating method, long-time heat treatment is possible. An appropriate heat treatment apparatus may be selected in consideration of the irradiation conditions of the cluster ions 16.

In the second step of the present embodiment, the second epitaxial layer 20 formed on the first modified layer 18 includes a silicon epitaxial layer, and the peak concentration of the dopant element contained therein is the semiconductor as described above. The peak concentration of the dopant element added to the wafer 10 is lower. The second epitaxial layer can be formed, for example, under the following conditions. A source gas such as dichlorosilane or trichlorosilane is introduced into the chamber using hydrogen as a carrier gas, and the growth temperature differs depending on the source gas used, but the semiconductor wafer is formed by CVD at a temperature in the range of about 1000 to 1200 ° C. 10 can be epitaxially grown. The dopant concentration in the second epitaxial layer can be adjusted by the amount of dopant gas introduced during epitaxial growth. As the dopant gas, for example, diborane gas (B ₂ H ₆ ) can be used in the case of boron doping, and phosphine (PH ₃ ) in the case of phosphorus doping. The second epitaxial layer 20 preferably has a thickness in the range of 1 to 15 μm. If the thickness is less than 1 μm, the resistivity of the second epitaxial layer 20 may change due to the out-diffusion of the dopant from the semiconductor wafer 10, and if it exceeds 15 μm, the spectral sensitivity characteristics of the solid-state imaging device are affected. This is because there is a risk of occurrence. The second epitaxial layer 20 becomes a device layer for manufacturing a back-illuminated solid-state imaging device.

  In the second embodiment shown in FIG. 2, one feature is that the first cluster ion irradiation is performed not on the bulk semiconductor wafer 12 but on the first epitaxial layer 14. A bulk semiconductor wafer has an oxygen concentration about two orders of magnitude higher than that of an epitaxial layer. Therefore, in the modified layer formed in the bulk semiconductor wafer, more oxygen is diffused than the first modified layer formed in the epitaxial layer, and much oxygen is captured. The trapped oxygen is re-emitted from the capture site during the device process and diffuses into the active region of the device, forming point defects, thus adversely affecting the electrical properties of the device. Therefore, an important design condition in the device process is to irradiate an epitaxial layer having a low solid solution oxygen concentration with cluster ions and form a gettering layer in the epitaxial layer in which the influence of oxygen diffusion can be almost ignored.

(Semiconductor epitaxial wafer)
Next, semiconductor epitaxial wafers 100 and 200 obtained by the above manufacturing method will be described. The semiconductor epitaxial wafer 100 according to the first embodiment and the semiconductor epitaxial wafer 200 according to the second embodiment include the semiconductor wafer 10 and the front of the semiconductor wafer 10 as shown in FIGS. 1 (F) and 2 (G). The first modified layer 18 formed by dissolving a predetermined element in the semiconductor wafer 10 formed on the surface 10A and the predetermined element dissolved in the semiconductor wafer 10 formed on the back surface 10B of the semiconductor wafer 10 are formed. A second modified layer 19 and an epitaxial layer 20 on the first modified layer 18. The half-value widths W _A and W _B of the concentration profile in the depth direction of the predetermined element in the first modified layer 18 and the second modified layer 19 are both 100 nm or less.

That is, according to the manufacturing method of the present invention, since the precipitation region of the elements constituting the cluster ions can be locally and highly concentrated as compared with the monomer ion implantation, both of the half widths W _A and W _B can be obtained. It became possible to set it to 100 nm or less. The lower limit can be set to 10 nm. In the present specification, the “concentration profile of a predetermined element” means a concentration distribution of each element in the depth direction measured by secondary ion mass spectrometry (SIMS). Moreover, the “half-value width of the concentration profile” on the front surface side is measured by SIMS in a state where the epitaxial layer is thinned to 1 μm when the thickness of the epitaxial layer exceeds 1 μm in consideration of measurement accuracy. The half value width when the concentration profile of the predetermined element is measured.

  The predetermined element to be dissolved is not particularly limited as long as it is an element other than the main material of the semiconductor wafer (silicon in the case of a silicon wafer), but preferably contains carbon, and further includes boron, phosphorus, arsenic and dopant elements. As described above, it is preferable to include one or more elements selected from the group consisting of antimony.

From the viewpoint of obtaining a higher gettering capability, both of the semiconductor epitaxial wafers 100 and 200 have a depth of 150 nm or less from the front surface of the semiconductor wafer 10 and the predetermined element in the first modified layer 18 is within the range of 150 nm or less. It is preferable that the peak of the concentration profile of the predetermined element in the second modified layer 19 is located in the range where the peak of the concentration profile is located and the depth from the back surface of the semiconductor wafer 10 is 150 nm or less. The peak concentration of the concentration profile of the predetermined element in the first modified layer 18 is preferably 1 × 10 ¹⁵ atoms / cm ³ or more, more preferably in the range of 1 × 10 ¹⁷ to 1 × 10 ²² atoms / cm ^3. The range of 1 × 10 ¹⁹ to 1 × 10 ²¹ atoms / cm ³ is more preferable. The peak concentration of the concentration profile of the predetermined element in the second modified layer 19 is preferably 1 × 10 ¹⁵ atoms / cm ³ or more, and is within the range of 1 × 10 ¹⁷ to 1 × 10 ²² atoms / cm ³ . Is more preferable, and the range of 1 × 10 ¹⁹ to 1 × 10 ²¹ atoms / cm ³ is more preferable.

  In addition, the thickness in the depth direction of the first modified layer 18 and the second modified layer 19 can be approximately in the range of 30 to 400 nm.

The specific resistance of the semiconductor wafer 10 is preferably 1.0 to 50 mΩ · cm, and more preferably 5.0 to 30 mΩ · cm. The peak concentration of the dopant element in the semiconductor wafer 10 is preferably 1.0 × 10 ^{18 to} 1.0 × 10 ²⁰ atoms / cm ³ , and preferably 1.0 × 10 ^{18 to} 1.0 × 10 ¹⁹ atoms / cm ³ or more. More preferred. Further, the peak concentration of the dopant element in the epitaxial layer 20 is preferably 1.0 × 10 ^{13 to} 1.0 × 10 ¹⁶ atoms / cm ³ , and 5.0 × 10 ^{13 to} 1.0 × 10 ¹⁵ atoms / cm ^3. The following is more preferable. The dopant element is not particularly limited, and phosphorus and boron can be used.

  According to the semiconductor epitaxial wafers 100 and 200 of the present embodiment, metal contamination can be further suppressed by exhibiting higher gettering capability on the front and back surfaces than in the prior art.

(Method for manufacturing solid-state imaging device)
In the method for manufacturing a solid-state imaging device according to the embodiment of the present invention, the solid-state imaging device is formed on the second epitaxial layer 14 of the epitaxial wafer manufactured by the above-described manufacturing method or the above-described epitaxial wafer, that is, the semiconductor epitaxial wafers 100 and 200. It is characterized by doing. The solid-state imaging device obtained by this manufacturing method can sufficiently suppress the occurrence of white defect as compared with the conventional case.

(Reference Example 1)
An n-type silicon wafer (diameter: 300 mm, thickness: 725 μm, dopant: phosphorus, dopant concentration: 5 × 10 ¹⁴ atoms / cm ³ ) obtained from a CZ single crystal was prepared. Next, a cluster ion generator (manufactured by Nissin Ion Instruments Co., Ltd., model number: CLARIS) is used to generate and ionize C ₅ H ₅ clusters from dibenzyl (C ₁₄ H ₁₄ ), and a dose of 9.0 × 10 ^The silicon wafer was irradiated under conditions of ¹³ Clusters / cm ² (carbon dose amount 4.5 × 10 ¹⁴ atoms / cm ³ ) and acceleration voltage 14.8 keV / atom per carbon atom.

(Reference Example 2)
For the same silicon wafer as in Reference Example 1, instead of cluster ion irradiation, carbon monomer ions are generated using CO ₂ as a material gas, a dose amount of 9.0 × 10 ¹³ atoms / cm ² , an acceleration voltage of 300 keV / The silicon wafer was irradiated under the atom conditions.

(SIMS measurement result)
About the sample produced in the said reference examples 1 and 2, it measured by secondary ion mass spectrometry (SIMS: Secondary Ion Mass Spectrometry), and obtained the carbon concentration profile shown in FIG. 4 for reference. The depth of the horizontal axis is zero on the front surface of the silicon wafer. As is clear from FIG. 4, the carbon concentration profile is sharp in Reference Example 1 where cluster ion irradiation is performed, but the carbon concentration profile is broad in Reference Example 2 where monomer ions are implanted. Further, in Reference Example 1, the peak concentration of the carbon concentration profile is higher than that in Reference Example 2, and the peak position is located closer to the semiconductor wafer surface. From this, it is presumed that the tendency of the concentration profile of each element is the same after the formation of the epitaxial layer.

Example 1
An n-type silicon wafer (diameter: 300 mm, thickness: 725 μm, dopant type: phosphorus, dopant concentration: 1 × 10 ¹⁵ atoms / cm ³ ) obtained from a CZ single crystal was prepared. Next, C ₅ H ₅ cluster ions are generated from dibenzyl (C ₁₄ H ₁₄ ) as a first cluster ion using a cluster ion generator (manufactured by Nissin Ion Equipment Co., Ltd., model number: CLARIS). The front surface of the silicon wafer was irradiated under irradiation conditions of 0 × 10 ¹³ Clusters / cm ² (carbon dose amount 4.5 × 10 ¹⁴ atoms / cm ³ ) and 14.8 keV / atom per carbon atom. Next, as the second cluster ion, C ₅ H ₅ cluster ions are generated from dibenzyl (C ₁₄ H ₁₄ ) in the same manner as the first cluster ions, and the carbon dose is 9.0 × 10 ¹³ Clusters / cm ² , carbon The back surface of the silicon wafer was irradiated under an irradiation condition of 14.8 keV / atom per atom. After that, the silicon wafer is transferred into a single wafer epitaxial growth apparatus (Applied Materials Co., Ltd.), subjected to a hydrogen baking process at a temperature of 1120 ° C. for 30 seconds, and then hydrogen as a carrier gas and trichlorosilane as a source. A silicon epitaxial layer (thickness: 8 μm, dopant type: phosphorus, dopant concentration: 1 × 10 ¹⁵ atoms / cm ³ ) is epitaxially grown on a silicon wafer by CVD at 1000 to 1150 ° C. in gas, and silicon according to the present invention An epitaxial wafer was produced.

(Example 2)
A silicon epitaxial wafer according to the present invention was produced in the same manner as in Example 1 except that the dose amount of cluster ions irradiated on the front and back surfaces of the silicon wafer was 6.0 × 10 ¹³ Clusters / cm ² .

(Example 3)
A silicon epitaxial wafer according to the present invention was produced in the same manner as in Example 1 except that C ₃ H ₅ cluster ion irradiation was used instead of C ₅ H ₅ cluster ion irradiation on the front and back surfaces.

Example 4
A silicon epitaxial wafer according to the present invention was produced in the same manner as in Example 3 except that the dose amount of cluster ions irradiated on the front and back surfaces of the silicon wafer was 6.0 × 10 ¹³ Clusters / cm ² .

(Comparative Example 1)
Except that instead of cluster ion irradiation on the front and back surfaces of the silicon wafer, carbon monomer ions were generated using CO ₂ as the material gas, and the injection energy was injected only to the front surface of the silicon wafer at an injection energy of 300 keV / atom. In the same manner as in Example 1, a silicon epitaxial wafer according to a comparative example was produced.

(Comparative Example 2)
A silicon epitaxial wafer according to a comparative example was produced in the same manner as in comparative example 1 except that the dose amount of carbon monomer ions was changed to 6.0 × 10 ¹³ atoms / cm ² .

(Evaluation method and evaluation results)
Each sample produced in the above Examples and Comparative Examples was evaluated. The evaluation method is shown below.

(1) SIMS measurement First, in order to clarify the difference in carbon concentration profile between cluster ion irradiation and monomer ion implantation, SIMS measurement was performed on Example 1 and Comparative Example 1 as representative examples. The obtained carbon concentration profiles are shown in FIGS. 5 (A), 5 (B) and FIG. 6 (6). Here, the depth of the horizontal axis in FIGS. 5A and 6 indicates that the front surface of the epitaxial layer of the epitaxial silicon wafer is zero, and the depth of the horizontal axis in FIG. Zero.

  Further, for each sample prepared in Examples 1 to 4 and Comparative Examples 1 and 2, the half-value width and peak position of the carbon concentration profile on the front side when SIMS measurement was performed after thinning the epitaxial layer to 1 μm ( Table 1 shows the peak concentration from the front surface of the silicon wafer excluding the epitaxial layer) and the peak concentration. Tables 1 to 4 also show the half-value width, peak position, and peak concentration of the carbon concentration profile on the back surface side for Examples 1 to 4.

(2) Evaluation of gettering capability The front surface of the epitaxial layer and the back surface of the silicon wafer of each sample produced were intentionally formed using a Ni contamination liquid (1.0 × 10 ¹³ atoms / cm ² ) using a spin coat contamination method. Contaminated and subsequently subjected to diffusion heat treatment at 900 ° C. for 30 minutes. Thereafter, the gettering performance was evaluated by performing SIMS measurement on each of the front surface and the back surface. Ni capture amounts (integrated values of SIMS profiles) were classified as follows and used as evaluation criteria. The evaluation results are shown in Table 1.
◎: 1 × 10 ¹² atoms / cm ² or more ○: 7.5 × 10 ¹¹ atoms / cm ² or more to less than 1 × 10 ¹² atoms / cm ² Δ: 7.5 × 10 ¹¹ atoms / cm ^{2 or} less −: Not yet Evaluation

(Consideration of evaluation results)
5A and 5B are compared with FIG. 6, in Example 1, the modified layer in which carbon is locally dissolved in a high concentration is formed on both the front surface and the back surface by cluster ion irradiation. It can be seen that And as shown in Table 1, Examples 1-4 were superior to Comparative Examples 1 and 2 because the full width at half maximum of the carbon concentration profile was 100 nm or less on the front surface and the back surface. It can be seen that the gettering ability is exhibited on the front and back surfaces. On the other hand, in Comparative Examples 1 and 2, Ni can be captured only on the front surface side, and the gettering capability is inferior to the gettering capability on the front side of Examples 1 to 4.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor epitaxial wafer which can suppress metal contamination by exhibiting higher gettering capability, its manufacturing method, and the solid-state image sensor which forms a solid-state image sensor from this semiconductor epitaxial wafer A manufacturing method can be provided.

DESCRIPTION OF SYMBOLS 10 Semiconductor wafer 10A The front surface 10B of a semiconductor wafer The back surface 12B of a semiconductor wafer 12 Bulk semiconductor wafer 14 1st epitaxial layer 16 1st cluster ion 17 2nd cluster ion 18 1st modified layer 19 2nd modified layer 20 (1st 2) Epitaxial layer 100 Semiconductor epitaxial wafer 200 Semiconductor epitaxial wafer

Claims (17)

Irradiating the front surface of the semiconductor wafer with first cluster ions and the back surface with second cluster ions, the first modified layer comprising the constituent elements of the first cluster ions on the front surface of the semiconductor wafer Forming a second modified layer made of a constituent element of the second cluster ions on the back surface of the semiconductor wafer; and
A second step of forming an epitaxial layer on the first modified layer of the semiconductor wafer;
Have
The first cluster ion and the second cluster ion both comprise carbon and hydrogen as constituent elements, and a method for producing a semiconductor epitaxial wafer.   The method for producing a semiconductor epitaxial wafer according to claim 1, wherein the semiconductor wafer is a silicon wafer.   The method for producing a semiconductor epitaxial wafer according to claim 1, wherein a peak concentration of the dopant element in the semiconductor wafer is higher than a peak concentration of the dopant element in the epitaxial layer.   The semiconductor wafer is an epitaxial silicon wafer in which a silicon epitaxial layer is formed on a front surface of a silicon wafer, and the first modified layer is formed on a front surface of the silicon epitaxial layer in the first step. The method for producing a semiconductor epitaxial wafer according to claim 1, wherein the second modified layer is formed on a back surface of the silicon wafer.   5. The method according to claim 1, wherein, after the first step, the second step is performed by transferring the semiconductor wafer to an epitaxial growth apparatus without performing a heat treatment for recovering crystallinity on the semiconductor wafer. The manufacturing method of the semiconductor epitaxial wafer of description.   The manufacturing method of the semiconductor epitaxial wafer of any one of Claims 1-4 which performs the heat processing for crystallinity recovery with respect to the said semiconductor wafer after the said 1st process and before the said 2nd process.   The first and / or second cluster ions further include a dopant element as a constituent element, and the dopant element is one or more elements selected from the group consisting of boron, phosphorus, arsenic, and antimony. The manufacturing method of the semiconductor epitaxial wafer of any one of 1-6. The irradiation conditions of the first cluster ions are: an acceleration voltage per carbon atom is 50 keV / atom or less, a cluster size is 100 or less, and a carbon dose is 5.0 × 10 ¹⁵ atoms / cm ² or less. The manufacturing method of the semiconductor epitaxial wafer of any one of -7. The irradiation conditions of the second cluster ions are an acceleration voltage per carbon atom of 50 keV / atom or less, a cluster size of 100 or less, and a carbon dose of 1.0 × 10 ¹⁴ atoms / cm ² or more. The manufacturing method of the semiconductor epitaxial wafer of any one of 1-8. A semiconductor wafer, a first modified layer formed by dissolving a predetermined element in the semiconductor wafer formed on the front surface of the semiconductor wafer, and the semiconductor wafer formed on the back surface of the semiconductor wafer A second modified layer formed by dissolving a predetermined element therein, and an epitaxial layer on the first modified layer,
The half-value widths of the concentration profiles in the depth direction of the predetermined element in the first modified layer and the second modified layer are both 100 nm or less,
The first modified layer is formed by irradiation with first cluster ions whose constituent elements are carbon and hydrogen, and the second modified layer is formed by irradiation with second cluster ions whose constituent elements are carbon and hydrogen. A semiconductor epitaxial wafer characterized by comprising:   The semiconductor epitaxial wafer according to claim 10, wherein the semiconductor wafer is a silicon wafer.   The semiconductor epitaxial wafer according to claim 10 or 11, wherein a peak concentration of the dopant element in the semiconductor wafer is higher than a peak concentration of the dopant element in the epitaxial layer.   The semiconductor wafer is an epitaxial silicon wafer in which a silicon epitaxial layer is formed on a front surface of a silicon wafer, the first modified layer is located on a front surface of the silicon epitaxial layer, and the second modified The semiconductor epitaxial wafer according to claim 10, wherein the quality layer is located on a back surface of the silicon wafer.   The peak of the concentration profile in the first modified layer is located within a depth of 150 nm or less from the front surface of the semiconductor wafer, and the depth from the back surface of the semiconductor wafer is 150 nm or less. The semiconductor epitaxial wafer according to claim 10, wherein a peak of the concentration profile in the second modified layer is located inside. The peak concentration of the concentration profile in the first modified layer is 1 × 10 ¹⁵ atoms / cm ³ or more, and the peak concentration of the concentration profile in the second modified layer is 1 × 10 ¹⁵ atoms / cm ^3. It is the above, The semiconductor epitaxial wafer of any one of Claims 10-14.   16. The device according to claim 10, wherein the predetermined element further includes a dopant element, and the dopant element is one or more elements selected from the group consisting of boron, phosphorus, arsenic, and antimony. Semiconductor epitaxial wafer.   In the epitaxial layer located in the front surface of the epitaxial wafer manufactured by the manufacturing method of any one of Claims 1-9, or the epitaxial wafer of any one of Claims 10-16, A method for manufacturing a solid-state imaging device, comprising forming a solid-state imaging device.

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