JP2010283219A - Method for manufacturing semiconductor substrate dedicated to semiconductor device, and method and apparatus for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor substrate dedicated to a semiconductor device, for easily forming a gettering site for capturing heavy metal in a short time. <P>SOLUTION: One surface 2a of a signal crystal wafer 2 is simultaneously irradiated with a plurality of laser beams R from an irradiation surface 21a of a laser irradiator 21 forming a laser irradiation device along a plurality of optical axes C parallel to each other. The plurality of laser beams R simultaneously emitted from the irradiation surface 21a of the laser irradiator 21 are condensed so that a condensing point (focal point) may be in a position which is tens of micrometers deep from the one surface 2a of the single crystal wafer 2. Thus, a crystal structure of the single crystal wafer 2 is modified and a plurality of gettering sinks 4 are simultaneously formed by one-time irradiation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor substrate for a semiconductor device, a method for manufacturing a semiconductor device, and a manufacturing apparatus for a semiconductor device, and more particularly to a technique capable of easily forming a gettering site in a short time.

  In recent years, with the drastic thinning of cellular phones, digital video cameras and the like, semiconductor devices built into these devices, such as semiconductor memories, have been thinned. Such a semiconductor memory is manufactured, for example, by forming a device on one surface of a silicon substrate (silicon wafer) made of a silicon single crystal. In order to reduce the thickness of the semiconductor memory, after forming a device on the front surface side of the silicon substrate, the back surface side of the silicon substrate is shaved to reduce the thickness to about 50 μm, for example.

  In such a semiconductor device thinning process, there is a concern that heavy metals may be mixed into the silicon substrate. When impurities such as heavy metals are mixed in the silicon substrate, the device characteristics are remarkably deteriorated due to leakage current or the like. For this reason, it is important to suppress the dispersion of heavy metals in the device formation region after the thinning process of the silicon substrate.

  Conventionally, a gettering method is generally known as a method for removing heavy metals from a silicon substrate. In this method, a heavy metal capturing region called a gettering site is formed on a silicon substrate, and the heavy metal is collected at the gettering site by annealing or the like, thereby reducing the heavy metal in the element formation region.

  As a method for forming such a gettering site on a silicon substrate, for example, an IG (intrinsic gettering) method for forming an oxygen precipitate on the silicon substrate (for example, Patent Document 1), backside damage on the back side of the silicon substrate, etc. An EG (exotic trickling) method (for example, Patent Document 2) that forms a gettering site is known.

JP-A-6-338507 JP 2006-313922 A

  The conventional IG method is used in a previous step of forming a device on a silicon substrate, and requires a heat treatment temperature of 600 ° C. or higher in order to remove heavy metals diffused in the silicon substrate. However, the heat treatment temperature performed after the device is formed on the silicon substrate is almost 400 ° C. or less, and there is a problem that the heavy metal mixed in the thinning process after the device formation cannot be sufficiently captured.

  Moreover, with the progress of thinning of semiconductor devices in recent years, the thickness is required to be 50 to 40 μm or less, and further about 30 μm. At such a level of thickness, most of the gettering sink formed on the silicon substrate is scraped off in the thinning process, and there is a problem that sufficient gettering capability cannot be obtained.

  On the other hand, in the EG method for forming a gettering site such as backside damage on the back side of a silicon substrate, a large-diameter substrate such as a 300 mm wafer, which has become mainstream in recent years, is polished on both sides, so that the getter is formed on the back side. It is difficult to form a ring sink itself.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a semiconductor substrate for a semiconductor device that can easily form a gettering site for capturing heavy metals in a short time. .

  Another object of the present invention is to provide a method of manufacturing a semiconductor device that can easily and reliably remove heavy metals contaminated after the formation of a semiconductor element from the element formation region.

  Another object of the present invention is to provide a semiconductor device manufacturing apparatus capable of easily forming a gettering site for capturing heavy metals in a short time.

In order to solve the above-described problems, the present invention provides the following method for manufacturing a semiconductor substrate for a semiconductor device, a method for manufacturing a semiconductor device, and a semiconductor device manufacturing apparatus.
That is, the method for manufacturing a semiconductor substrate for a semiconductor device according to the present invention uses a laser irradiation apparatus capable of irradiating a laser beam with a plurality of optical axes parallel to each other from the irradiation surface, and simultaneously lasers at least two places on one surface of the semiconductor substrate. A plurality of getters in which a multi-photon absorption process is caused in each minute region by changing the crystal structure of the minute region by making a beam incident and condensing the laser beam on the minute regions of the semiconductor substrate. It is characterized by comprising at least a gettering sink forming step for forming a ring sink.

The laser beam is preferably an ultrashort pulse laser beam having a pulse width of 1.0 × 10 ^{−15 to} 1.0 × 10 ⁻⁸ seconds and a wavelength of 300 to 1200 nm.
In addition, the ultrashort pulse laser beam has a peak power density of 1.0 × 10 ^{6 to} 1.0 × 10 ¹¹ seconds W / cm ² and a beam diameter of 1 μm to 10 mm in the minute region. Preferably it is controlled.

The semiconductor substrate is preferably made of single crystal silicon, and the gettering sink preferably includes at least amorphous silicon.
The gettering sink formation step is preferably performed in a non-oxidizing gas atmosphere containing at least one of nitrogen, argon, and hydrogen.
An epitaxial growth step of forming an epitaxial crystal layer on one surface of the semiconductor substrate may be further provided.

  The semiconductor device manufacturing method of the present invention includes an element formation step of forming a semiconductor element at a position overlapping each gettering sink of the semiconductor substrate for a semiconductor device obtained by the method for manufacturing a semiconductor substrate for a semiconductor device of the above-mentioned items. And a gettering step of annealing the semiconductor substrate for conductor devices at a predetermined temperature and capturing the heavy metal in the gettering sink.

The semiconductor device manufacturing apparatus of the present invention has a plurality of ultrashort pulse laser beams having a pulse width of 1.0 × 10 ^{−15 to} 1.0 × 10 ⁻⁸ seconds and a wavelength of 300 to 1200 nm that are parallel to each other from the irradiation surface. And a laser irradiation body for irradiating the semiconductor substrate with the optical axis.

The laser irradiator includes at least one laser light source and a plurality of light guide members for guiding an ultrashort pulse laser beam emitted from the laser light source so as to be emitted from the irradiation surface with a plurality of optical axes. Just do it.
Further, the laser irradiator may be one in which a plurality of laser light sources are arranged on the irradiation surface.

  According to the method for manufacturing a semiconductor substrate for a semiconductor device of the present invention, a multiphoton absorption process is performed on a minute region inside the semiconductor substrate by condensing the laser beam on an arbitrary minute region inside the semiconductor substrate. As a result, it is possible to easily form a gettering sink in which only the crystal structure of the minute region is changed.

  In such a gettering sink formation process, for example, a single laser beam is scanned by simultaneously (at one time) irradiating a plurality of laser beams along a plurality of optical axes parallel to each other from the irradiation surface. Compared with a method of irradiating a laser beam while moving a semiconductor substrate, a large number of gettering sinks can be formed simultaneously in a considerably short time. Also, even for large-diameter single crystal wafers, if the number of laser light sources formed along the irradiation surface is increased, a large number of gettering sinks can be integrated at once without increasing the formation time of gettering sinks at all. Can be formed.

  According to the method for manufacturing a semiconductor device of the present invention, in the step of forming a gettering sink, a plurality of laser beams are irradiated simultaneously (at a time) along a plurality of optical axes parallel to each other from the irradiation surface. Thus, since a large number of gettering sinks can be formed in a short time, it is possible to easily and quickly manufacture a high-performance semiconductor device in which heavy metals are reliably captured.

  In addition, according to the semiconductor device manufacturing apparatus of the present invention, a laser irradiation body that irradiates a semiconductor substrate with a plurality of optical axes parallel to each other on an irradiation surface is formed, so that a plurality of laser beams can be simultaneously (one). A large number of gettering sinks can be formed simultaneously in a short time.

It is sectional drawing which shows an example of the semiconductor substrate for semiconductor devices. It is sectional drawing which shows an example of a semiconductor device. It is sectional drawing which shows the manufacturing method of the semiconductor substrate for semiconductor devices of this invention. It is an expanded sectional view which shows the formation process of a gettering sink. It is explanatory drawing which shows an example of the manufacturing apparatus of the semiconductor device of this invention. It is a perspective view which shows an example of a laser irradiation body. It is explanatory drawing which shows another example of the manufacturing apparatus of the semiconductor device of this invention.

    DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a semiconductor device manufacturing method, a semiconductor device manufacturing method, and a semiconductor device manufacturing apparatus according to the present invention will be described with reference to the drawings. Note that this embodiment is described by way of example in order to better understand the gist of the invention, and does not limit the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, there is a case where a main part is shown in an enlarged manner for convenience, and the dimensional ratio of each component is the same as the actual one. Not necessarily.

  First, a configuration example of a semiconductor substrate for a semiconductor device will be described. FIG. 1 is an enlarged cross-sectional view showing a semiconductor substrate for a semiconductor device of the present invention. A semiconductor substrate for semiconductor devices (hereinafter simply referred to as a semiconductor substrate) 1 includes a single crystal wafer 2 and an epitaxial layer 3 formed on one surface 2 a of the single crystal wafer 2. In the vicinity of the surface 2a of the single crystal wafer 2, gettering sinks 4, 4,... For capturing heavy metals on the semiconductor substrate 1 are formed.

  Such a semiconductor substrate 1 can be suitably used as a substrate for a semiconductor device, for example, a substrate for manufacturing a solid-state imaging device. The single crystal wafer 2 may be, for example, a silicon single crystal wafer. Epitaxial layer 3 may be an epitaxially grown film of silicon grown from one surface 2 a of single crystal wafer 2.

  The gettering sink 4 may have a structure in which a part of a silicon single crystal is made amorphous (amorphous-like). The gettering sink 4 has a capability of capturing heavy metals only by a slight strain in its crystal structure, and can serve as a gettering sink by making only a small part amorphous.

  The gettering sink 4 is formed by modifying the crystal structure by causing a multiphoton absorption process in a part of the single crystal wafer 2 by condensing the laser beam. A method for forming such a gettering sink 4 will be described later in detail in a method for manufacturing a semiconductor substrate for a semiconductor device.

The gettering sink 4 only needs to be formed at a position that overlaps at least each semiconductor element, for example, the formation region S of the solid-state imaging element, when the solid-state imaging element is formed using the semiconductor substrate 1. For example, one gettering sink 4 may be formed in a disk shape having a diameter R of 50 to 150 μm and a thickness T of 10 to 150 μm. The formation depth D of the gettering sink 4 is preferably about 0.5 to 2 μm from the one surface 2 a of the single crystal wafer 2.
Such a gettering sink 4 may be formed in the epitaxial layer 3 formed in the upper layer of the single crystal wafer 2.

Next, a configuration example of a semiconductor device using a semiconductor substrate for a semiconductor device will be described. In the following embodiments, a solid-state image sensor is taken as an example of a semiconductor device.
FIG. 2 is a cross-sectional view showing an example of a solid-state imaging device created using the epitaxial substrate for a solid-state imaging device of the present invention. The solid-state imaging device 60 is a semiconductor substrate (for semiconductor devices) in which a p-type epitaxial layer 3 is formed on a p ⁺ -type semiconductor substrate (silicon substrate) 2 and a gettering sink 4 is formed on a single crystal wafer 2. A semiconductor substrate 1 is used.

  A first n-type well region 61 is formed at a predetermined position of the epitaxial layer 2. Inside the first n-type well region 61, a p-type transfer channel region 63, an n-type channel stop region 64, and a second n-type well region 65 constituting a vertical transfer register are formed.

  Further, a transfer electrode 66 is formed at a predetermined position of the gate insulating film 62. Further, a photodiode (semiconductor element) in which an n-type positive charge accumulation region 67 and a p-type impurity diffusion region 68 are stacked between the p-type transfer channel region 63 and the second n-type well region 65. 69 is formed. Then, an interlayer insulating film 71 that covers them and a light shielding film 72 that covers the surface except for the portion directly above the photodiode 69 are provided.

  In the solid-state imaging device 60 having such a configuration, the heavy metal contained in the semiconductor substrate 1 is reliably captured by the gettering sink 4 formed on the single crystal wafer 2, so that the imaging characteristics of the solid-state imaging device 60 are deteriorated. It is possible to suppress the dark leakage current of the photodiode (semiconductor element) 69, which is a cause of the occurrence of the above.

  Therefore, by forming the solid-state image sensor 60 using the semiconductor substrate 1 of the present invention, it is possible to realize the solid-state image sensor 60 having excellent imaging characteristics with little dark leakage current.

Next, the manufacturing method of the semiconductor substrate for semiconductor devices of this invention and the manufacturing method of a semiconductor device using the same are demonstrated. FIG. 3 is a cross-sectional view showing stepwise a method for manufacturing a solid-state imaging device which is an example of a semiconductor device.
In manufacturing a solid-state imaging device (semiconductor device), first, a single crystal wafer 2 is prepared (see FIG. 3A). The single crystal wafer 2 may be, for example, a silicon single crystal wafer manufactured by slicing a silicon single crystal ingot.

  Next, it is preferable to form the epitaxial layer 3 on one surface 2a of the single crystal wafer 2 (see FIG. 3B: epitaxial growth step). In forming the epitaxial layer 3, for example, an epitaxial growth apparatus is used to introduce a source gas while heating the single crystal wafer 2 to a predetermined temperature, and the epitaxial layer 3 made of silicon single crystal is formed on one surface 2 a of the single crystal wafer 2. It only has to grow.

  Next, the single crystal wafer 2 on which the epitaxial layer 3 is formed is set in the laser irradiation apparatus 20, and a laser beam is irradiated toward the one surface 2a of the single crystal wafer 2 (see FIG. 3C). At this time, as shown in FIG. 4, a plurality of laser beams R are simultaneously emitted from the irradiation surface 21a of the laser irradiation body 21 constituting the laser irradiation apparatus 20 along a plurality of optical axes C parallel to each other. Irradiation is directed toward one surface 2 a of the wafer 2.

  A plurality of laser beams R simultaneously emitted from the irradiation surface 21a of the laser irradiation body 21 are focused on one surface of the single crystal wafer 2 by a condensing means (not shown) such as a condensing lens in advance. The light is condensed so as to be at a position about 2 to several tens of micrometers deep. As a result, the crystal structure of the single crystal wafer 2 is modified, and a plurality of gettering sinks 4 are simultaneously formed by one irradiation (gettering sink forming step).

  In this gettering sink formation step, the chamber 43 accommodating the single crystal wafer 2 is filled with nitrogen, argon, hydrogen, or a gas G obtained by mixing these gases, and the chamber 43 is filled with a non-oxidizing gas atmosphere. It is preferable to do this. Thus, when the laser beam R is irradiated, it is possible to prevent oxygen in the air and the single crystal wafer 2 from being combined by the generated heat to form a silicon oxide film.

  The semiconductor substrate for a semiconductor device of the present invention is obtained by the above steps. A semiconductor device is manufactured using the semiconductor substrate 1 composed of the single crystal wafer 2 on which the epitaxial layer 3 and the gettering sink 4 are formed.

  As shown in FIG. 3D, a plurality of semiconductor elements, for example, photodiodes (semiconductor elements) 69 are arrayed on one surface 3a of the epitaxial layer 3 of the semiconductor substrate 1 (element forming step). The photodiode (semiconductor element) 69 may be configured as shown in FIG. At this time, each photodiode (semiconductor element) 69 may be formed at a position overlapping the gettering sink 4.

  Then, as shown in FIG. 3E, the semiconductor substrate 1 on which a large number of photodiodes (semiconductor elements) 69 are formed is introduced into an annealing apparatus 80 and heated to a predetermined temperature (gettering step). Thereby, the heavy metal diffused in the single crystal wafer 2 is collected in the gettering sink 4, and the solid-state image pickup device (semiconductor device) having very little heavy metal in the element formation portion, that is, the formation region of the photodiode (semiconductor element) 69. 60 is obtained.

  FIG. 5 is a schematic diagram showing an example of a semiconductor device manufacturing apparatus of the present invention, that is, a laser irradiation apparatus for forming a gettering sink on a semiconductor wafer. The laser irradiation apparatus (semiconductor device manufacturing apparatus) 20 includes a laser irradiation body 21 that irradiates a laser beam toward the semiconductor substrate 1 with a plurality of optical axes R parallel to each other from the irradiation surface 21a.

The laser irradiation body 21 is formed, for example, in a substantially circular shape that is the same as or larger than the single crystal wafer 2. A large number of laser generation sources, for example, laser diodes 15, 15... Are formed along the irradiation surface 21a facing the single crystal wafer 2.
As shown in FIG. 6, the laser diodes 15, 15... Are regularly arranged so as to spread on the substantially circular irradiation surface 21a. The formation position of each laser diode 15 may be set to a position that matches (overlaps) the formation position of the semiconductor element formed on the semiconductor substrate 1, for example.

  Referring again to FIG. 5, the laser irradiation apparatus 20 is provided with a stage 40 on which the single crystal wafer 2 is placed, and a chamber 43 that hermetically accommodates the stage 40 and the laser irradiation body 21. In addition, a pulse control unit 16 that controls oscillation of the laser beam emitted from the laser irradiation body 21 is provided.

  Further, by moving the stage 40 up and down, the distance between the single crystal wafer 2 and the irradiation surface 21a of the laser irradiation body 21 is controlled to control the formation position (depth) of the gettering sink 4. And a CPU 50 for controlling the laser irradiation apparatus 20 including the pulse control unit 16 and the stage control unit 45.

  The laser diodes 15, 15... Are not particularly limited as long as they can irradiate a laser beam in a wavelength region that can form a gettering sink by modifying the crystal structure at an arbitrary position inside the single crystal wafer 2. Table 1 shows specific examples of suitable laser irradiation conditions for each of a general semiconductor wafer and a silicon wafer.

Next, a method for forming a gettering sink on the single crystal wafer 2 on which the epitaxial layer 3 is formed will be described in detail. FIG. 4 is a schematic diagram showing how a gettering sink is formed on a semiconductor wafer by a laser beam.
When forming a gettering sink on the single crystal wafer 2, the single crystal wafer 2 on which the epitaxial layer 3 is formed is placed on the stage 40 of the laser irradiation apparatus 20. Then, a plurality of laser beams R are simultaneously irradiated onto one surface 2a of the single crystal wafer 2 from a plurality of laser diodes 15, 15... Arranged along the irradiation surface 21a of the laser irradiation body 21.

Each laser beam R may be an ultrashort pulse laser beam having a pulse width of 1.0 × 10 ^{−15 to} 1.0 × 10 ⁻⁸ seconds and a wavelength of 300 to 1200 nm, for example. Since such a laser beam R has a wavelength range that can be transmitted with respect to silicon, it reaches the surface of the epitaxial layer 3 and then enters as it is without being reflected.

On the other hand, the single crystal wafer 2 on which the epitaxial layer 3 is formed is controlled by the height of the stage 40 so that the condensing point (focal point) of the laser beam R is a predetermined depth D from the one surface 2a of the single crystal wafer 2. Positioned. As a result, the single crystal wafer 2 undergoes a multiphoton absorption process only at the condensing point (focal point) of the laser beam R. Note that, at the condensing point of the laser beam R, that is, the formation position of the gettering sink 4, the peak output density of the laser beam R is in the range of 1.0 × 10 ^{6 to} 1.0 × 10 ¹¹ seconds W / cm ² . It is preferable to be controlled so that

  As is well known, the multiphoton absorption process irradiates a specific part (irradiation region) with a large amount of photons in a very short time, so that a large amount of energy is selectively absorbed only in the irradiation region. It causes a reaction such as a change in the crystal bond in the region.

  In the present invention, a laser beam is focused on an arbitrary region inside the single crystal wafer 2 to modify the semiconductor wafer having a single crystal structure at this focusing point (focal point) and partially amorphous like. A crystal structure. Such modification of the crystal structure may be performed to such an extent that a capturing action of heavy metals is generated, that is, a slight distortion is generated in the crystal structure.

  As described above, the condensing point (focal point) of the laser beam R is set in an arbitrary minute region inside the single crystal wafer 2, and the crystal structure of the minute region is modified, whereby the arbitrary crystal region of the single crystal wafer 2 is changed. A large number of gettering sinks 4 can be formed in the minute region.

  Further, in this gettering sink formation step, the chamber 43 (see FIG. 5) that accommodates the single crystal wafer 2 is filled with nitrogen, argon, hydrogen, or a mixed gas in which these gases are mixed, and the chamber 43 is filled with non-filling. An oxidizing gas atmosphere is preferable. Thus, when the laser beam is irradiated, it is possible to prevent a silicon oxide film from being formed due to the combination of oxygen in the air and the single crystal wafer due to the generated heat.

  The laser beam R for forming the gettering sink 4 modifies the crystal structure of the epitaxial layer 3 or the single crystal wafer 2 in the optical path before the laser beam R reaches the focal point (focal point). It is important to ensure that the laser beam can be reliably transmitted.

  Such laser beam irradiation conditions are determined by a forbidden band (energy band gap) which is a basic physical property value of a semiconductor material. For example, since the forbidden band of a silicon semiconductor is 1.1 eV, the transmittance becomes remarkable when the incident wavelength is 1000 nm or more. In this way, the wavelength of the laser beam can be determined in consideration of the forbidden band of the semiconductor material.

The laser beam R is preferably an ultrashort pulse laser such as a femtosecond laser. Since this ultrashort pulse laser can reduce the pulse width of the excitation laser beam to 1.0 × 10 ⁻¹⁵ femtoseconds or less, it can suppress the diffusion of thermal energy generated by excitation compared to other lasers. Light energy can be concentrated only at the focal point of the beam.

  It is presumed that the gettering sink 4 formed by modifying the crystal structure by the multiphoton absorption process probably has an amorphous-like crystal structure. In order to obtain such an amorphous-like crystal structure, it is necessary for the laser beam to rapidly heat and cool the condensing point (focal point) G locally. The ultrashort pulse laser having the characteristics shown in Table 1 has sufficient energy to locally rapidly heat the single crystal wafer 20 by focusing using a focusing means or the like.

  The temperature of the focal point G of the laser beam reaches a high temperature of 9900 to 10000K. In addition, since the light is collected, the heat input range is very narrow, and when irradiation is stopped after irradiation for a short time, the amount of heat input at the condensing point (focal point) is drastically reduced, and a rapid cooling effect is obtained.

  Further, as in the ultrashort pulse laser shown in Table 1, by setting the wavelength to 1000 nm, the transparency to the epitaxial layer 3 and the single crystal wafer 2 is enhanced, and the crystal structure of the epitaxial layer 3 and the like is affected. In addition, only the minute region that is the focal point (focal point) of the laser beam can be modified. This modified portion of the crystal structure can be suitably used as the gettering sink 4 of the single crystal wafer 2.

  When the wavelength of the laser beam exceeds 1200 nm, the photon energy (laser beam energy) becomes low because of the long wavelength region. For this reason, even if the laser beam is condensed, there is a possibility that sufficient photon energy for modifying the inside of the semiconductor substrate cannot be obtained, and the wavelength of the laser beam is preferably set to 1200 nm or less.

  The position of the condensing point (focal point) G of the laser beam, that is, the position where the gettering sink 4 is formed on the single crystal wafer 2 can be controlled by moving the stage up and down. Besides the vertical movement of the stage, the position of the condensing point (focal point) G of the laser beam can also be controlled by controlling the position of the condensing means (not shown).

  As an example, when the gettering sink 4 is formed by modifying the position of 2 μm from the surface of the semiconductor substrate, the wavelength of the laser beam is set to 1080 nm and the condensing lens with a transmittance of 60% (magnification 50) The modified portion (gettering sink) can be formed by forming (condensing) a laser beam at a position 2 μm from the surface using a (multiplier) and generating a multiphoton absorption process.

  In this way, the gettering sink 4 obtained by modifying the crystal structure of the minute region of the single crystal wafer 2 is formed in a disk shape having a diameter r of 50 to 150 μm and a thickness t of 10 to 150 μm, for example. It only has to be done. The formation depth d of the gettering sink 4 is preferably about 0.5 to 2 μm from the one surface 2 a of the single crystal wafer 2.

  Each gettering sink 4 should just be formed in the semiconductor substrate 1 in the position which overlaps with the formation area S of a solid-state image sensor. For example, the gettering sink 4 may be formed with a formation pitch p of 0.1 μm to 10 mm.

  The formation density (getting interval) of the laser diodes 15, 15... Arranged in a large number on the irradiation surface 21 a of the laser irradiation body 21 constituting the laser irradiation apparatus 20. It depends on.

  For example, the formation density of the gettering sink 4 can be increased by closely arranging smaller laser diodes. It is also possible to increase the formation density of the gettering sink 4 by finely moving the single crystal wafer 2 within a range smaller than the formation pitch of the laser diodes 15 and 15 and performing laser irradiation again after one laser irradiation. is there.

The formation density of such gettering sinks 4 is preferably in the range of 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ pieces / cm ² , for example. The formation density of the gettering sink 4 can be verified by the number of oxygen precipitates obtained by observation with a cross-sectional TEM (transmission electron microscope).

  As described above, according to the method for manufacturing a semiconductor substrate for a semiconductor device of the present invention, the multi-photon absorption is performed in a minute region inside the semiconductor substrate by condensing the laser beam on an arbitrary minute region inside the semiconductor substrate. It is possible to easily form a gettering sink in which only the crystal structure of the minute region is changed by generating a process.

  In such a gettering sink formation process, for example, a single laser beam is scanned by simultaneously (at one time) irradiating a plurality of laser beams along a plurality of optical axes parallel to each other from the irradiation surface. Compared with a method of irradiating a laser beam while moving a semiconductor substrate, a large number of gettering sinks can be formed simultaneously in a considerably short time. Even for large-diameter single crystal wafers such as 300 mm wafers and 450 mm wafers, increasing the number of laser light sources formed along the irradiated surface increases the number of gettering sinks without increasing the formation time at all. These gettering sinks can be formed in a lump.

  In addition, by applying the semiconductor substrate manufacturing method for semiconductor devices to the semiconductor device manufacturing method, a large number of gettering sinks can be formed in a short time, making it easy to perform high-performance semiconductor devices in which heavy metals are reliably captured. In addition, it can be manufactured in a short time.

FIG. 7 is a schematic diagram showing another example of a semiconductor device manufacturing apparatus of the present invention, that is, a laser irradiation apparatus for forming a gettering sink on a semiconductor wafer. In addition, the same code | symbol is attached | subjected to the structure similar to the laser irradiation apparatus shown in FIG. 5, and detailed description is abbreviate | omitted.
This laser irradiation apparatus (semiconductor device manufacturing apparatus) 90 includes a laser irradiation body 91 that irradiates a semiconductor substrate 1 with a plurality of optical axes R parallel to each other from an irradiation surface 91a.

  The laser irradiation body 91 includes a laser source, for example, a pulse laser device 93 such as a femtosecond laser, and a plurality of light guide members (optical fibers) 94 extending from the pulse laser device 93 toward the irradiation surface 91a.・ It is equipped with. Each light guide member 94 has one end facing the pulse laser device 93 and the other end arranged on the irradiation surface 91a.

  With such a configuration, the laser beam emitted from one pulse laser device 93 reaches the irradiation surface 91a through each of a large number of light guide members (optical fibers) 94, 94. Then, the semiconductor substrate 2 is irradiated as a plurality of laser beams R along a plurality of optical axes parallel to each other from the irradiation surface 91a, and a large number of gettering sinks 4 are simultaneously formed.

According to the laser irradiation apparatus (semiconductor device manufacturing apparatus) 90 having such a configuration, a laser beam irradiated from one pulse laser apparatus (laser light source) is divided by a light guide member, and a large number of laser beams are irradiated from the irradiation surface 91a. Therefore, it is possible to provide a laser irradiation apparatus that is low-cost and easy to control.
Further, when the formation density of the gettering sink 4 is changed, it is only necessary to increase / decrease the light guide member, so that it is possible to cope with the increase in the diameter of the single crystal wafer at a low cost.

1 ... Semiconductor substrate (semiconductor substrate for semiconductor devices)
2 ... single crystal wafer 3 ... epitaxial layer 4 ... gettering sink 20 ... laser irradiation apparatus (semiconductor device manufacturing apparatus)
21 ... Laser irradiation body 21a ... Irradiation surface

Claims (10)

  Using a laser irradiation apparatus capable of irradiating a laser beam with a plurality of optical axes parallel to each other from the irradiation surface, at least two places on one surface of the semiconductor substrate are simultaneously irradiated with the laser beam, and the plurality of minute regions of the semiconductor substrate are incident At least a gettering sink forming step for forming a plurality of gettering sinks by causing a multiphoton absorption process in each minute region by focusing the laser beam and changing the crystal structure of the minute region A method of manufacturing a semiconductor substrate for a semiconductor device. 2. The semiconductor device according to claim 1, wherein the laser beam is an ultrashort pulse laser beam having a pulse width of 1.0 × 10 ^{−15 to} 1.0 × 10 ⁻⁸ seconds and a wavelength of 300 to 1200 nm. For manufacturing a semiconductor substrate. The ultra-short pulse laser beam is controlled so that the peak power density is 1.0 × 10 ^{6 to} 1.0 × 10 ¹¹ seconds W / cm ² and the beam diameter is 1 μm to 10 mm in the minute region. The method of manufacturing a semiconductor substrate for a semiconductor device according to claim 1 or 2.   4. The method of manufacturing a semiconductor substrate for a semiconductor device according to claim 1, wherein the semiconductor substrate is made of single crystal silicon, and the gettering sink includes at least amorphous silicon.   5. The semiconductor device semiconductor according to claim 1, wherein the gettering sink formation step is performed in a non-oxidizing gas atmosphere containing at least one of nitrogen, argon, and hydrogen. A method for manufacturing a substrate.   6. The method of manufacturing a semiconductor substrate for a semiconductor device according to claim 1, further comprising an epitaxial growth step of forming an epitaxial crystal layer on one surface of the semiconductor substrate. An element forming step of forming a semiconductor element at a position overlapping each gettering sink of the semiconductor substrate for a semiconductor device obtained by the method for manufacturing a semiconductor substrate for a semiconductor device according to any one of claims 1 to 6,
Gettering step of annealing the semiconductor substrate for the conductor device at a predetermined temperature and capturing the heavy metal in the gettering sink;
A method for manufacturing a semiconductor device, comprising: Irradiation of the semiconductor substrate with an ultrashort pulse laser beam having a pulse width of 1.0 × 10 ^{−15 to} 1.0 × 10 ⁻⁸ seconds and a wavelength of 300 to 1200 nm from the irradiation surface with a plurality of optical axes parallel to each other. An apparatus for manufacturing a semiconductor device, comprising:   The laser irradiation body includes at least one laser light source and a plurality of light guide members for guiding an ultrashort pulse laser beam emitted from the laser light source so as to be emitted from the irradiation surface with a plurality of optical axes. The semiconductor device manufacturing apparatus according to claim 8.   9. The apparatus for manufacturing a semiconductor device according to claim 8, wherein the laser irradiation body includes a plurality of laser light sources arranged on the irradiation surface.

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