JP2005060168A - Method for producing wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing wafers, by which the time required for heat treatment for imparting IG capability can be shortened in the production of the wafers and the wafers each having high IG (ingot) capability can be produced in large quantities. <P>SOLUTION: This method for producing the wafers includes a BMD forming process for forming inner micro-defects (BMD) at the inside by subjecting a silicon single crystal in an ingot state to heat treatment and a wafer processing process for processing the ingot in which the inner micro-defects (BMD) are formed into wafers. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a wafer, and more particularly, to a method for manufacturing a wafer in which oxygen precipitates for imparting IG (Intrinsic Gettering) ability and internal micro defects BMD (Bulk Micro Defect) are produced at low cost.

  Silicon single crystal wafers used as substrates for semiconductor integrated circuit elements are mainly manufactured by the Czochralski method (CZ method). With the CZ method, a seed crystal of a silicon single crystal is immersed in a silicon melt melted at a high temperature of 1420 ° C. or higher in a quartz crucible, and the seed crystal is gradually pulled up while rotating the quartz crucible and the seed crystal. This is a method for growing a cylindrical silicon single crystal. At this time, the surface of the quartz crucible in contact with the silicon melt is melted, and oxygen is dissolved in the silicon melt and is taken into the growing crystal. The oxygen atoms aggregate during crystal growth and cooling and become oxygen precipitation nuclei. Therefore, when a silicon wafer collected from the grown crystal is subjected to heat treatment in a temperature range of 700 ° C. to 1050 ° C., this nucleus grows to form oxygen precipitates and BMD. This oxygen precipitate plays a beneficial role in capturing metal contamination that occurs in the process of forming integrated circuit elements (device process). This is so-called intrinsic gettering (IG).

  It is clear that the future device process will be further integrated and the temperature of the process using high energy ion implantation will be lowered. In this case, it is difficult to form BMD during the device process due to the low temperature of the process. It is predicted to become. Therefore, it is difficult to obtain a sufficient IG effect in the low temperature process as compared with the high temperature process. Moreover, even if the device process is lowered in temperature, heavy metal contamination due to high energy and ion implantation is unavoidable, and gettering technology is considered essential. In order to suppress the occurrence of slip, it is preferable that high-density BMD exists.

  Ordinary BMD is formed by heat-treating the wafer after wafer processing. For example, a heat treatment called DZ-IG heat treatment is known. This is because a mirror-processed wafer processed at a high temperature is processed at a temperature of about 1100 ° C. to 1200 ° C., oxygen in the vicinity of the wafer surface is diffused outwardly, and interstitial oxygen serving as nuclei of minute defects is reduced. Then, a defect-free DZ (Denuded Zone) layer is formed in the device active region. Thereafter, a high-temperature + low-temperature two-stage heat treatment is performed in which BMD is formed in the wafer bulk by a low-temperature heat treatment at 600 ° C. to 900 ° C. Further, a low temperature treatment is first performed to sufficiently form a BMD, and a DZ layer on the wafer surface layer may be formed by a subsequent high temperature heat treatment. A wafer that has been heat-treated in such a wafer state and added with a DZ layer or an IG capability is called an annealed wafer.

  In recent years, the wafer (ingot) is doped with nitrogen so that crystal-induced defects such as COP (Crystal Originated Particle) are easily eliminated and oxygen precipitates are easily obtained. ing.

  Further, a crystal is known which is composed of a region having excess atomic vacancies but no crystal growth introduction defects (crystal defects such as COP) and a region having excess interstitial silicon atoms but no crystal growth introduction defects. This is obtained by controlling the crystal pulling speed and the like, and can be a wafer having almost no crystal defects. Such a crystal consisting of a region having excess vacancies but no crystal growth introduction defects and a region having excess interstitial silicon atoms but no crystal growth introduction defects is called a quasi-perfect crystal. Sometimes called NPC. Even if such a crystal is used, an annealed wafer having a wide surface defect-free region (DZ layer) can be effectively manufactured (see, for example, Patent Document 1).

  However, for example, the annealing referred to as the DZ-IG heat treatment as described above takes a very long time because the wafer is subjected to two-stage heat treatments for different purposes, ie, DZ layer formation and BMD formation. In particular, in order to form BMD with high density, it is necessary to perform heat treatment at a low temperature for a sufficient time.

  Further, when heat treatment is performed in a wafer state processed into a silicon wafer, a vertical heat treatment apparatus 30 as shown in FIG. 6 is used, and a wafer W set in a heat treatment boat 40 is heated by a heater 32 in a chamber 31. Heat. In addition, a heat treatment boat 40 as shown in FIG. 7 is used for setting the wafer, and the wafer W is held on a groove-like wafer mounting portion 43 provided on a plurality of support columns 42 connected by a connecting portion 41. However, the number of wafers that can be set is limited to about 100 at most. Therefore, in order to produce a large number of annealed wafers, it is necessary to prepare a large number of heat treatment apparatuses or shorten the annealing time.

  However, since the diameter of the wafer is increased, the apparatus for performing such heat treatment is also increased in size, and the heat treatment boat used for the apparatus is also increased in size, so that a very expensive apparatus is required. Therefore, there is a cost limit for introducing many apparatuses, and it is important to operate the heat treatment apparatus efficiently.

Japanese Patent Application Laid-Open No. 11-199387

  An object of the present invention is to provide a method for manufacturing a wafer that can shorten the heat treatment for imparting IG capability in the manufacture of a wafer and can produce a large amount of wafers having a high IG capability.

  The present invention for solving the above-mentioned problems is a method for manufacturing a wafer, comprising at least a BMD forming step in which an internal micro defect (BMD) is formed by performing a heat treatment on a silicon single crystal in an ingot state, and the internal micro defect A wafer manufacturing method comprising a wafer processing step of processing an ingot in which a defect (BMD) is formed into a wafer (claim 1).

  In this way, heat treatment is performed in advance on a silicon single crystal in an ingot state as a BMD formation step, and BMD is applied to a silicon single crystal in a wafer state as in the past by processing the ingot into a wafer in a wafer processing step. Heat treatment can be performed more efficiently than the method of adding heat treatment to be formed, and wafers with high IG ability can be produced in large quantities. In addition, a wafer having a high IG capability can be supplied to a subsequent process such as a device process from the beginning.

In this case, in the BMD forming step, it is preferable to perform heat treatment at 700 ° C. or higher on the silicon single crystal in the ingot state.
Thus, sufficient BMD can be formed inside by performing a heat treatment at 700 ° C. or higher on the silicon single crystal in the ingot state.

In this case, the BMD forming step is preferably performed at a heat treatment temperature of 1100 ° C. or lower for 30 minutes to 8 hours.
By performing heat treatment at a heat treatment temperature of 1100 ° C. or lower, heat treatment can be performed without generating dislocations or slips in the single crystal. Moreover, favorable IG capability can be provided by performing the heat processing for 30 minutes or more and 8 hours or less.

In this case, it is preferable that the BMD forming step is heat-treated at a temperature rising rate of 0.5 ° C./min to 10 ° C./min.
A stable BMD can be formed in the ingot by performing heat treatment at such a temperature rising rate. In order to precipitate BMD at a high density, it is preferable to slowly raise the temperature to 5 ° C./min or less in a temperature zone region where BMD precipitation nuclei are generated, for example, 500 ° C. or more. In the region lower than this (less than 500 ° C.), the temperature may be raised at a relatively high speed of about 10 ° C./min.

In this case, the silicon single crystal is preferably a crystal doped with nitrogen.
By doping nitrogen into the silicon single crystal in this way, BMD can be easily formed by heat treatment.

In this case, the silicon single crystal may be a quasi-perfect crystal (NPC) region crystal manufactured by the Czochralski method.
With such a crystal, for example, when an annealed wafer is used in a later step, a higher quality wafer having a thick DZ layer can be obtained.

In this case, the silicon single crystal in the ingot state is an ingot that has been pulled up by a single crystal pulling apparatus using the Czochralski method, or an ingot that has been cylindrically ground after being pulled and cut into a block shape. (Claim 7).
In the present invention, since the BMD is formed in the silicon single crystal in such an ingot state by heat treatment, the BMD can be efficiently formed in the single crystal.
In addition, the shape of the ingot that has been pulled by the single crystal pulling apparatus referred to in the present invention is the crystal immediately after being pulled by the Czochralski method, as well as the cone portion and tail portion being cut from the pulled ingot. And those cut into several blocks.

Hereinafter, the present invention will be described in detail.
When manufacturing a wafer having a high IG capability, the inventor forms a BMD for increasing the IG effect by heat treatment in an ingot state, and by processing the wafer, the BMD is formed and the wafer having a high IG capability is formed. It has been found that the BMD density can be sufficiently maintained in the subsequent process of forming the DZ layer or epitaxial layer.

  Conventional ingot annealing (hereinafter sometimes referred to as ingot annealing) is a technique mainly performed in compound semiconductors such as GaAs, and is performed exclusively to improve electrical characteristics uniformly (for example, (See JP-A-6-196430 and JP-A-6-31854). In the present invention, unlike such a heat treatment, a heat treatment for forming a BMD is performed on a silicon single crystal in an ingot state, whereby a wafer having a high IG ability is produced in a large amount in a short time. That is, the wafer manufacturing method of the present invention is characterized in that BMD is formed inside an ingot-state silicon single crystal and then wafer processing is performed.

  In the present invention, the BMD is formed in the ingot state as described above, and the wafer is processed to produce a wafer to which the IG capability is added. For example, when an annealed wafer is subsequently produced, The heat treatment under the condition for adding the IG capability can be omitted or simplified, and the heat treatment time can be shortened. Further, for example, even when an epitaxial wafer is formed by forming an epitaxial layer on such a wafer, a wafer having a high gettering effect can be obtained. In addition, since it is a heat treatment in an ingot state, it is not necessary to use a wafer heat treatment boat as compared with a heat treatment for forming a BMD in a conventional wafer state, so that a large amount of heat treatment can be performed at a time (in terms of wafer). The heat treatment efficiency can be greatly improved.

  Specifically, the silicon single crystal in an ingot state is subjected to a heat treatment at 700 ° C. or higher, and then wafer processing is performed. In particular, a heat treatment process for forming a BMD in an ingot by performing a heat treatment on a silicon single crystal in an ingot state is preferably performed at a heat treatment temperature of 700 ° C. to 1100 ° C. for 30 minutes to 8 hours. Moreover, stable BMD can be formed by heat-treating at a rate of temperature rise of 0.5 ° C./min to 10 ° C./min.

  By performing heat treatment at a temperature of 1100 ° C. or lower in the ingot state, it is possible to prevent dislocations and slips from occurring in the entire ingot. Moreover, sufficient BMD can be formed by heat-processing at the temperature of 700 degreeC or more. Furthermore, by performing heat treatment at a temperature of 700 ° C. or higher, a BMD that does not disappear in a subsequent process (for example, an annealing process in a wafer state) can be formed.

  In such a temperature range, if the ingot is subjected to, for example, constant temperature holding for 30 minutes or more and within 8 hours or heat treatment at multiple stages, sufficient BMD can be formed, and this BMD does not disappear even in subsequent steps. Since it remains, good IG capability can be imparted. The processing time is not particularly limited, and this processing time may be longer. However, the above range is suitable for obtaining time merit and good IG capability. At this time, it is preferable to raise the temperature at a rate of temperature rise of 0.5 ° C./min to 10 ° C./min.

The ingot is preferably a crystal in which a silicon single crystal is doped with nitrogen or a crystal in the NPC region.
In particular, when heat treatment is performed using a nitrogen-doped silicon single crystal, oxygen precipitates are likely to be obtained inside the crystal, and defects due to crystals such as COP are likely to disappear by heat treatment. By using such a silicon single crystal, for example, a wafer having a wide defect-free region and a high IG effect can be effectively manufactured when the step of forming the DZ layer is performed later.

Similarly, a crystal in the NPC region is preferable because it becomes a wafer having a wide defect-free region. By controlling the crystal pulling conditions, the crystal in the NPC region has an excess of atomic vacancies but no crystal growth introduction defect (sometimes referred to as an Nv region) and an interstitial silicon atom excess but a crystal growth introduction defect. It is a crystal grown in a region with no (sometimes referred to as Ni region).
In particular, it is known that the oxygen precipitation behavior is different between the Nv region and the Ni region in the NPC region. When exhibiting such different oxygen precipitation behavior, for example, by growing BMD from a low temperature region such as 300 to 500 ° C. at a slow temperature increase rate of about 0.5 to 2 ° C./min in the ingot stage, Nv or Ni region This is preferable because the behavior of oxygen precipitation is uniformized and BMD can be stably formed in the surface. Conventionally, when such a heat treatment is performed in a wafer state, the productivity is remarkably lowered, so that it has not been practically possible. However, in the ingot stage, even if such a slow heat treatment is performed, a large amount of treatment can be performed at one time, so that high productivity can be maintained.

Note that the silicon single crystal in the ingot state is an ingot that has been pulled up by a single crystal pulling apparatus or an ingot that has been cylindrically ground after being pulled and cut into blocks. The silicon single crystal pulled by the single crystal pulling device has cone and tail parts, but it is in such an ingot state (in addition to the cone and tail parts removed, and divided into multiple blocks. Ingot annealing can be performed.
In addition, before wafer processing (before slicing), the ingot is usually subjected to cylindrical grinding and then divided into a plurality of blocks. However, heat treatment may be performed in the state of such cylindrically ground blocks. In this case, metal contamination due to cylindrical grinding occurs on the surface layer of the block. Therefore, it is preferable to perform heat treatment after removing the surface layer of about 100 to 500 μm by acid etching.

  According to the method for manufacturing a wafer according to the present invention, since heat treatment for forming a BMD in an ingot state is performed first, a wafer having a high IG capability can be supplied to a subsequent process such as a device process. Also, heat treatment for forming BMD can be performed efficiently by carrying out a large amount at a time, and the heat treatment time for imparting IG capability can be greatly shortened, thereby improving the productivity of wafer manufacturing. Can do.

  The wafer manufacturing method of the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 are flowcharts showing the outline of the manufacturing process of the wafer of the present invention.

(Ingot training)
First, a silicon single crystal ingot is grown by adjusting the oxygen concentration (or nitrogen concentration), resistivity, etc. by the CZ method. This pulling method is not particularly limited, and a conventional method may be used. In particular, it is preferable to pull up the ingot under conditions that reduce defects due to crystals such as COP.

  In particular, by doping nitrogen into the silicon single crystal, it is possible to grow a silicon single crystal that is easy to form BMD. In the present invention, in order to grow a silicon single crystal ingot doped with nitrogen, when growing a silicon single crystal by the Czochralski method, nitride is put in advance in a quartz crucible or in a silicon melt. Nitrogen can be doped into the silicon single crystal by introducing nitride or changing the atmosphere gas to an atmosphere containing nitrogen or the like. At this time, the amount of nitrogen doped in the crystal can be controlled by adjusting the amount of nitride, the concentration of nitrogen gas, the introduction time, or the like.

  Also, by using a silicon single crystal in a quasi-perfect crystal (NPC) region, an annealed wafer having a thick DZ layer can be manufactured when annealing is performed in a wafer state later. In order to manufacture the silicon single crystal in the quasi-perfect crystal region, for example, the pulling speed V when the single crystal is grown by the Czochralski method, the crystal temperature gradient G in the pulling axis direction near the solid-liquid interface, By controlling crystal pulling while controlling the ratio V / G, a silicon single crystal in a quasi-perfect crystal (NPC) region can be pulled over the entire crystal cross section.

(Ingot annealing: BMD formation process)
Next, the ingot grown in this way is heat-treated in the form of an ingot to form BMD therein. That is, heat treatment is performed before the slicing process (before the wafer processing process) for processing into a wafer shape. In this case, it heat-processes on the conditions in which BMD is formed. At this time, the ingot annealing is performed in a state where the ingot is pulled up by the single crystal manufacturing apparatus or is cylindrically ground after being pulled and cut into blocks. That is, it can be performed either before or after cylindrical grinding of the outer periphery of the ingot.

First, an embodiment of ingot annealing in a shape as it is pulled up will be described (FIG. 1).
In this example, the ingot pulled up by the single crystal manufacturing apparatus is not removed, and the ingot is put into a heat treatment furnace without being divided into a plurality of blocks, and heat treatment is performed to form a BMD.
The heat treatment apparatus in this case is not particularly limited, but a heat treatment apparatus capable of performing heat treatment in such an ingot lump state is preferable, and a horizontal heat treatment furnace as shown in FIG. 3 is suitable. FIG. 3 shows an outline of a horizontal heat treatment furnace. This heat treatment furnace 10 is a quartz or SiC chamber 11 in which an ingot 1 that is not divided into a plurality of blocks can be input as it is without removing a cone part and a tail part. And a heat treatment means such as a heater 12 is provided on the outside thereof. The ingot 1 is held by a support portion 13 that can support the cone portion and the tail portion (a support portion may be disposed at the center of the ingot as necessary). Using such an apparatus, the heat treatment is performed under the heat treatment conditions for forming the BMD.

  It is preferable to heat-treat such an ingot that has been pulled up because heat treatment can be performed in a state in which contamination or the like is as little as possible or in a state in which no distortion or the like is formed. In addition, if the ingot is heat-treated at a time and converted into a wafer, a very large number of wafers can be processed.

  Next, another example is shown. The following example shows an example in which ingot annealing is performed on an ingot that is not pulled up, but is cylindrically ground after being pulled up and cut into a block shape. (Figure 2)

  The side of the ingot pulled up in the ingot growing process is cylindrically ground, and then the cone portion 2 and tail portion 3 of the ingot 1 are cut as shown in FIG. Get.

Thereafter, heat treatment is performed on the block-shaped ingot. In addition, when such cylindrical grinding / blocking is performed, contamination and cracking may occur due to heat treatment. First, the entire ingot surface is first etched by several hundred μm with an etching solution and adhered to the ingot surface. Remove metallic impurities. As this etching solution, for example, an acidic etching solution made of HF / HNO ₃ is used.

  Then, it heat-processes in a heat treatment furnace with the state of a block. Although the heat treatment apparatus is not particularly limited, an ingot block having such a form can be heat treated as a lump, for example, the one shown in FIG. 4 is preferable. The heat treatment furnace 20 shown in FIG. 4 is an apparatus that can heat-treat the ingot block 4 in a vertical position. The ingot block 4 is put into a chamber 21 made of quartz or SiC from the lower side of the heat treatment furnace 20 and is placed outside the chamber. The heat treatment is performed by heat treatment means such as the heater 22 arranged, which is a so-called vertical heat treatment furnace. Using such a heat treatment furnace, heat treatment is performed under the heat treatment conditions for forming the BMD. Such heat treatment in which a silicon single crystal is formed into a block shape is preferable because the heat treatment furnace can be reduced in size.

  Even when heat treating an ingot that has been cylindrically ground and cut into a block after being pulled up in this way, a heat treatment boat for wafers is not required, so a large amount of silicon single crystal can be heat treated at one time. In terms of heat treatment, a very large number of wafers can be heat treated at one time.

  The specific heat treatment conditions for the BMD formation process as described above may be set as appropriate according to the required specifications. In particular, if heat treatment at 700 ° C. to 1100 ° C. is performed for about 30 minutes to 8 hours in an oxygen atmosphere, BMD to be generated is sufficiently generated. Actually, the temperature is raised from room temperature to around 500 ° C. at a high rate of about 10 ° C./minute, and then the temperature rise rate is slowed down until the set temperature is about 0.5 ° C./minute to 5 ° C./minute. Raise the temperature. In this way, the temperature is gradually raised to a set temperature (for example, 1000 ° C.) and held at this set temperature for an arbitrary time (for example, 1 hour). Thereafter, the temperature is lowered to 600 ° C. at a temperature lowering rate of about 5 ° C./min. By doing so, BMDs that do not disappear even if heat treatment or epitaxial growth at about 1000 ° C. for forming the DZ layer later in the wafer state are formed at a high density in the ingot.

(Wafer processing process)
Next, the ingot annealed ingot in this way is subjected to wafer processing. In the wafer processing, the process is not particularly limited as long as a wafer having at least high flatness can be obtained. In this embodiment, as shown in FIG. 8, after a single crystal silicon ingot is sliced to produce a thin plate (wafer) (FIG. 8A), this silicon wafer is chamfered (FIG. 8B). Steps such as planarization (lapping) (FIG. 8C), etching (FIG. 8D), and polishing (FIG. 8E) are sequentially performed to finally obtain a mirror-polished wafer. The conditions of each process are not particularly limited, but in the slicing process (FIG. 8A), cutting using a wire saw, and in the flattening process (FIG. 8C), lapping (process) or surface grinding (process). Etc. For example, in the lapping process, lapping using loose abrasive grains of # 1500 or more is performed. Next, it is preferable to perform etching using an alkaline solution in the etching step (FIG. 8D), and polishing in a plurality of stages combining double-side polishing and single-side polishing in the polishing step (FIG. 8E). In addition, for the chamfering process (FIG. 8B), rough chamfering before flattening, mirroring of the chamfered portion (mirror chamfering), and the like are performed. In addition, a cleaning process may be performed after polishing or between the processes.
Thus, a wafer with high IG capability can be easily manufactured by performing wafer processing after performing ingot annealing.

(Example 1)
(Ingot training)
A silicon single crystal ingot having an oxygen concentration of 13 to 15 × 10 ¹⁷ atoms / cm ³ [oldASTM] and a nitrogen concentration of 5 to 9 × 10 ¹² atoms / cm ³ was grown by the CZ method. The ingot was cylindrically ground and cut into a plurality of blocks to obtain an ingot having a diameter of about 300 mm and a length of about 30 cm.

(Ingot annealing: BMD formation process)
The ingot was heat-treated in the ingot state, and a BMD forming step for forming BMD inside was performed. First, the entire ingot surface was etched by about 200 μm with an acid etching solution made of HF / HNO ₃ to remove metal impurities contaminating the surface.
Then, it heat-processed in the heat processing furnace shown in FIG. 4 with the state of the ingot.

In the heat treatment, the temperature was raised from room temperature to 500 ° C. at a temperature rising rate of 10 ° C./min, and then to 1000 ° C. at a temperature rising rate of 1 ° C./min, and kept at 1000 ° C. for 2 hours. Then, it cooled to 600 degreeC with the temperature-fall rate of about 5 degree-C / min, and dropped to room temperature at about 2 degree-C / min after that. Oxygen gas was used as the atmosphere during the heat treatment.
As a result, when converted into wafers, heat treatment for four batches of normal wafer heat treatment boats could be carried out in one heat treatment.

(Wafer processing process)
In the wafer processing step, the ingot after the BMD forming step was processed in the step shown in FIG. In the slicing step (FIG. 8A), cutting is performed using a wire saw, after the chamfering step (FIG. 8B), and in the flattening step (FIG. 8C), lapping is performed using # 1500 free abrasive grains. In the etching step (FIG. 8D), etching was performed with an alkaline solution using 50% NaOH. Thereafter, in the polishing step (FIG. 8E), three-stage polishing including double-side polishing, single-side polishing, and single-side polishing was performed to obtain a wafer having a mirror surface with high flatness. Thereafter, washing was performed. Approximately 300 silicon wafers having a diameter of 300 mm were obtained from the 30 cm ingot.

About the wafer obtained in this way, as a result of evaluating BMD density by the infrared tomography method, it was 3 * 10 < ⁹ > piece / cm < ³ > and sufficient BMD density. In other words, a wafer with high IG capability was obtained. Therefore, when an annealed wafer that forms a DZ layer, for example, in a later process using such a wafer, it is not necessary to perform a low-temperature heat treatment to form a BMD. Therefore, it is only necessary to perform heat treatment for forming the DZ layer, and the heat treatment time can be greatly shortened.

(Example 2)
A silicon single crystal ingot having an oxygen concentration of 13 to 15 × 10 ¹⁷ atoms / cm ³ [oldASTM] was grown by the CZ method. This silicon single crystal was grown in the NPC region by controlling the crystal growth rate. This ingot was cylindrically ground and cut into a plurality of blocks to obtain an ingot having a diameter of about 300 mm and a length of about 30 cm.

Thereafter, in the same manner as in Example 1, the BMD forming step and the wafer processing step were performed, and about 300 silicon wafers having a diameter of 300 mm were obtained. As a result of evaluating the BMD density by the infrared tomography method for the wafer thus obtained, a wafer having high BMD density of 3 × 10 ⁹ pieces / cm ³ and high IG ability was obtained.

(Comparative example)
After the ingot was manufactured in the same manner as in Examples 1 and 2, the wafer processing was performed without performing the BMD forming step in which the heat treatment was performed in the ingot state. The BMD density of this wafer was evaluated under the same conditions as in Examples 1 and 2 above.

  The wafer obtained from the ingot was not subjected to the BMD formation process in the ingot state, and the wafer was not formed. Therefore, no BMD was detected even if the above evaluation was performed. Therefore, when this wafer is used as, for example, an annealed wafer, heat treatment must be performed to form and grow BMD in the wafer state.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is the flowchart which showed an example of the manufacturing process of the wafer of this invention. It is the flowchart which showed another example of the manufacturing process of the wafer of this invention. It is explanatory drawing which showed an example of the horizontal heat processing furnace used at the BMD formation process in this invention. It is explanatory drawing which showed an example of the vertical heat processing furnace used at the BMD formation process in this invention. It is the figure which showed the ingot of the silicon single crystal of the state cut | disconnected in the block shape after pulling up. It is explanatory drawing which showed an example of the vertical heat processing apparatus used by the heat processing of a wafer. It is explanatory drawing which showed an example of the heat processing boat used by the heat processing of a wafer. It is the flowchart which showed an example of the wafer processing process in this invention.

Explanation of symbols

1 ... Ingot, 2 ... Cone, 3 ... Tail, 4 ... Block,
DESCRIPTION OF SYMBOLS 10 ... Heat processing furnace, 11 ... Chamber, 12 ... Heater, 13 ... Support part,
20 ... Heat treatment furnace, 21 ... Chamber, 22 ... Heater,
30 ... Heat treatment furnace, 31 ... Chamber, 32 ... Heater,
40 ... Heat treatment boat, 41 ... Connecting part, 42 ... Post, 43 ... Wafer mounting part,
W ... wah.

Claims (7)

  A method of manufacturing a wafer, wherein at least a BMD forming step of forming an internal micro defect (BMD) by performing heat treatment on an ingot-state silicon single crystal, and an ingot having the internal micro defect (BMD) formed on a wafer A wafer manufacturing method comprising a wafer processing step for processing.   The wafer manufacturing method according to claim 1, wherein in the BMD forming step, a heat treatment at 700 ° C. or higher is performed on a silicon single crystal in an ingot state.   3. The method for manufacturing a wafer according to claim 1, wherein in the BMD forming step, a heat treatment is performed at a heat treatment temperature of 1100 ° C. or lower for 30 minutes to 8 hours.   4. The wafer manufacturing method according to claim 1, wherein in the BMD forming step, heat treatment is performed at a temperature rising rate of 0.5 ° C./min to 10 ° C./min. 5.   The method for manufacturing a wafer according to any one of claims 1 to 4, wherein the silicon single crystal is a crystal doped with nitrogen.   6. The wafer manufacturing method according to claim 1, wherein the silicon single crystal is a crystal in a quasi-perfect crystal (NPC) region manufactured by a Czochralski method.   The silicon single crystal in the ingot state is an ingot that has been pulled up by a single crystal pulling apparatus using a Czochralski method, or an ingot that has been cylindrically ground after being pulled and cut into a block shape. The method for manufacturing a wafer according to any one of claims 1 to 6.

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