JP2001167995A - Wafer, epitaxial wafer and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon wafer, an epitaxial wafer having stable quality without adversely affecting the device characteristics by suppressing a boron contamination from the environment, and to provide a method for effectively manufacturing them. SOLUTION: The amount of boron adhered onto the surface of the wafer is set to 1×1010 atoms/cm2 or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon wafer and an epitaxial wafer having stable quality, a method for producing the same, and an air conditioner for a clean room.

[0002]

[Related Art] Due to the heat treatment in the device manufacturing process, the electrical characteristics of the material silicon wafer are changed by the impurity element in the silicon wafer or the impurity element attached to the silicon wafer, which may cause device failure. Is becoming increasingly important with the advancement of devices, and is a major challenge in device production.

As one of the measures, as shown in FIG. 10, a polycrystalline silicon layer [P
BS (Poly Back Seal) film] 62, and a method utilizing a crystal grain boundary present in the PBS film as an absorption source of an impurity element has been put into practical use. Wafers with films and epitaxial wafers are used as products.

[0004] Boron, particularly among the IIIB elements, is actively used to impart P-type conductivity to silicon and adjust its conductivity to a predetermined value, while handling silicon wafers. Boron adhering to the wafer from the atmosphere, devices and materials used in the wafer processing process diffuses into the silicon wafer during the heat treatment process, and becomes a disturbance factor that disturbs predetermined electrical characteristics of the wafer. It is required to prevent contamination by boron from materials and the like as much as possible.

[0005] Suppose that 1 × 10 ¹⁰ at
When boron of oms / cm ² is adhered and diffuses from the wafer surface to the inside (at a depth of about 1 μm), the value of the electrical resistivity is equivalent to several ohm · cm. • For wafers larger than cm, the electrical properties of the wafer surface layer on which the devices are made can vary considerably.

In addition, a wafer with a PBS film or a PB
In the case of an epitaxial wafer with an S film, the boron adhering to the wafer surface on which the PBS film is to be formed is PBS.
It diffuses mainly into the PBS film during the heat treatment in the film formation step and the subsequent epitaxial layer growth step. When boron adheres to the surface of the substrate on which the epitaxial layer is to be grown, these boron elements diffuse from the interface between the substrate and the epitaxial layer into the inside by heating during the growth of the layer. For these reasons, a predetermined characteristic may not be obtained in a device using an epitaxial wafer having an electrical resistivity of a substrate of several ohm · cm or more.

Further, during epitaxial layer growth in the manufacture of an epitaxial wafer, the PBS film on the back surface may be etched by the component gas in the growth chamber, particularly at the peripheral portion of the wafer, causing irregularities in film thickness and surface roughness. In order to prevent this, a silicon oxide film (CVD silicon oxide film) is further formed on the PBS film by a CVD (Chemical Vapor Deposition) method. When the contamination by boron occurs, the boron attached due to the temperature rise of the wafer in this step and the subsequent epitaxial layer growth step mainly includes PBS.
It diffuses in and adversely affects device characteristics as described above.

[0008] The above-mentioned conventional problems will be described more specifically by taking an example of an epitaxial wafer with a PBS film. FIGS. 10A and 10B are explanatory views showing a manufacturing process of a conventional epitaxial wafer with a PBS film, wherein FIG. 10A shows a silicon wafer W, FIG. 10B shows a state in which a polycrystalline silicon layer 62 is formed on the silicon wafer W, and FIG. In order to prevent the above-mentioned etching in the epitaxial layer growing step of (3), the CVD silicon oxide film 6 is further formed on the polycrystalline silicon layer (PBS film) 62 on the back surface of the silicon wafer W in (b).
4, (d) is a state in which the polycrystalline silicon layer 62 on the surface of the silicon wafer is removed by mirror polishing, and (e) is a state in which the epitaxial layer 66 is formed on the surface of the silicon wafer from the state of (d). Are respectively shown.

In manufacturing the conventional epitaxial wafer with the back PBS film, first, a silicon wafer W
Boron B adheres to the interface 70 between the silicon layer and the polycrystalline silicon layer (PBS film) 62, causing contamination [FIG. 10 (b)]. Next, contamination of boron B occurs at the interface 72 between the polycrystalline silicon layer 62 and the CVD film 64 (FIG. 10C). After removing the polycrystalline silicon layer 62 on the surface of the silicon wafer W [FIG. 10 (d)] and further passing through an epitaxial layer growth step (high-temperature heat treatment), boron B existing at the respective interfaces 70 and 72 is removed. Mainly diffuses into the PBS film 62 and contaminates the entire PBS film 62, resulting in a boron-contaminated PBS film 62a (FIG. 10E).

On the other hand, in a conventional clean room or the like (including a cleaning machine, a wafer storage, a film forming apparatus, etc.) for processing semiconductor wafers, for example, cleaning, transporting, storing, film forming, etc.
The quantitative relationship between the two and how much boron present in the atmosphere in contact with the wafer adheres to the wafer surface was completely unknown. Therefore, it is completely unclear how to control the boron concentration in the atmosphere in contact with the wafer so that the amount of boron adhering to the wafer can be suppressed to a value that does not impair the device characteristics. It has been difficult to effectively prevent boron contamination in manufacturing. In other words, the measurement of the amount of boron adhering to the wafer during the process requires a great amount of time, and the result cannot be immediately fed back to the apparatus side, making it impossible to perform online management for preventing boron contamination. It was possible. Therefore, as long as the prevention of boron contamination is controlled by measuring the amount of boron on the wafer, it has been difficult to produce a wafer of stable quality.

An air filter used in a conventional clean room (including a cleaning machine, a wafer storage, a film forming apparatus, etc.) for processing semiconductor wafers, for example, cleaning, transporting, storing, film forming, etc., is generally made of glass fiber. It is known that when a corrosive gas such as hydrogen fluoride gas is present in the atmosphere during wafer processing, boron is eluted into the atmosphere due to this adhesion.

For example, a configuration as shown in FIG. 11 is used as an air conditioner of a clean room. FIG.
Numeral 12 denotes an air conditioner constituting a clean room 14, in which various wafer processing chambers, in the illustrated example, a CVD processing chamber 16, a CVD furnace body chamber 18, a PBS film forming chamber 20, a PBS furnace A body chamber 22 is provided. Each of the chambers 16, 18, 20, and 22 is provided with one or more air inlets, and each of the air inlets has an air filter 16a, 16b, 18a, 20a, 20a.
b, 22a are provided.

Various wafer processing apparatuses are provided in each wafer processing chamber. For example, the CVD processing chamber 16 is provided with a pre-CVD processing washing machine 24, a dryer 26, and a clean booth 28 for storage. The CVD
A CVD apparatus 30 is arranged in the furnace chamber 18. In the PBS film forming chamber 20, a PBS film forming pre-washing machine 32,
A dryer 34 and a clean booth 36 for storage are provided. A PBS device 38 is disposed in the PBS furnace body chamber 22. Each of the above devices 24, 26, 28, 30, 3
Air filters 2 are provided at the air inlets of 2, 34, 36 and 38.
4a, 26a, 28a, 30a, 32a, 34a, 36
a, 38a are provided. 39 is clean room 1
4 is a space for discharging air provided on the downstream side. The air discharge space 39 is connected to a collection pipe 43.

On the upstream side of the clean room 14, an external conditioner 40, an impurity removing device 42, and an air conditioner 44 are arranged in series from upstream to downstream. The external controller 40
And the impurity removing device 42 are connected by a first air pipe 46, and the impurity removing device 42 and the air conditioner 44 are connected by a second air pipe 48. The air conditioners 44 and the air filters 16a, 16b, 18a, 20a, 20b,
22a is connected by a third air pipe 50.

The air conditioner 40 has a roll filter 99, a medium-performance filter 52 on the air inflow side, and a fan 54 on the air outflow side.
have. The impurity removing device 42 includes NOx and S
It is composed of a chemical filter for removing Ox. The air conditioner 44 has an air inlet fan 56, then a pre-filter 98, and a medium performance filter 58 on the air outlet side.

In the conventional clean room air conditioner 12 having the above-described configuration, the outside air is supplied to the outside air conditioner 40,
After passing through the impurity removing device 42 and the air conditioner 44, each air filter 16a, 16b, 18a, 20a, 20b,
22a, CVD processing chamber 16, CVD furnace main body 1
8, are introduced into the PBS film forming chamber 20 and the PBS furnace main body 22, respectively. The CVD process generally refers to a process in which one or several compound gases constituting a thin film material and a single gas are supplied onto a wafer, and a desired thin film is formed by a chemical reaction on a gas phase or a wafer surface. , For example, PB
The present invention can be applied as a process for preventing etching and autodoping of the PBS film in the epitaxial process by depositing silicon oxide on the back surface of the wafer on which the S film is formed.

The air introduced into each chamber is supplied to an air filter 2.
4a to the cleaning machine 24, and further to the air filter 26a.
To the dryer 26, to the clean booth 28 for storage via the air filter 28a, to the CVD device 30 via the air filter 30a, and to PB via the air filter 32a.
S is guided to the pre-cleaner 32, the dryer 34 via the air filter 34a, the clean booth 36 for storage via the air filter 36a, and the PBS device 38 via the air filter 38a. Evacuation space 39
Is discharged. However, a part of the gas is exhausted directly from the cleaning devices 24 and 32, and the entire amount is exhausted from the CVD device 30. The air discharged into the air discharge space 39 is about 80% of the entire supply amount.
% Through the collection pipe 43 and the second air pipe 48
Returned to and reused.

In such a conventional clean room air conditioner, air filters 16a, 16b, 18a,
20a, 20b, 22a, 24a, 26a, 28a, 3
0a, 32a, 34a, 36a, and 38a are ULPA filters (for example, NMO-32 manufactured by Nippon Inorganic Corporation).
0) is usually used. This ULPA filter has not only a function of removing boron but also a possibility of releasing boron. In addition, the medium performance filters 52 and 58 (for example, ASTC
Similarly, -56-95) does not have a function of removing boron, and may release boron. Therefore, it has not been possible to adjust the concentration of boron in the atmosphere in the clean room with a conventional clean room air conditioner incorporating such a filter.

Further, a boronless filter (an air filter that does not emit boron) and a boron adsorption filter (a filter that adsorbs boron) are known. However, these filters are effectively used to deposit boron on a wafer. At present, there has not yet been proposed a good measure for efficiently controlling the amount to a predetermined value or less. Although there are documents that mention the adverse effect of boron in the atmosphere in a clean room in the production of a bonded substrate, it points out the difficulty of realizing specific removal equipment (for example, Japanese Patent No. 2723787) only. No mention is made of effective removal of boron and control of the amount of boron in the atmosphere in the clean room within a predetermined range.

[0020]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems with the wafer and the epitaxial wafer, the present inventors have determined the boron concentration in the atmosphere in which these wafers and the epitaxial wafer are in contact with each other and the boron concentration in the atmosphere. Quantitatively grasp the relationship between the amount of boron adhering to the surface of these wafers, and experimentally clarified the effect of the amount of boron adhering to the boron concentration distribution in various products, Based on these findings, the inventors succeeded in stably producing silicon wafers and epitaxial wafers that suppress boron contamination from the environment and do not adversely affect device characteristics.

A first object of the present invention is to provide a silicon wafer, an epitaxial wafer, and a method for effectively manufacturing the same, which suppresses boron contamination from the environment and does not adversely affect device characteristics. .

In order to solve the above-mentioned problems of the conventional clean room air conditioner, the present inventors purify air in a clean room (including a cleaning machine, a wafer storage, a film forming apparatus, etc.) with an impinger. Dissolve in water and analyze it by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) to measure the boron concentration in the atmosphere, and study the relationship between this boron concentration and the boron concentration adsorbed on the wafer. As a result, they found that there was a certain relationship between the two, and succeeded in suppressing the boron concentration in the clean room atmosphere to a predetermined concentration or less.

A second object of the present invention is to provide an atmosphere control apparatus, a clean room and a clean room air-conditioning system capable of inexpensively preventing boron contamination on a wafer.

[0024]

In order to solve the above-mentioned first problem, a first aspect of the silicon wafer of the present invention is as follows.
The amount of boron deposited on the surface is 1 × 10 ¹⁰ atoms / cm ² or less.

According to a second aspect of the silicon wafer of the present invention, the increment of the boron concentration in the surface layer up to a depth of 0.5 μm with respect to the concentration of boron in the bulk silicon immediately below the surface layer is 1 × 10 ¹⁵ atoms / cm 2. ³ or less.

According to a third aspect of the silicon wafer of the present invention, there is provided a silicon wafer having a boron concentration of 1 μm in width including an interface between a polycrystalline silicon layer and a single crystal silicon layer. A polycrystalline layer whose increment with respect to the concentration is 1 × 10 ¹⁵ atoms / cm ³ or less is provided on one main surface.

A first aspect of the silicon epitaxial wafer of the present invention is a silicon epitaxial wafer having a polycrystalline silicon layer on the back surface of a single crystal silicon substrate, the width including the interface between the single crystal silicon and the polycrystalline silicon layer of the substrate. The increment of the boron concentration in the layer near the interface of 1 μm with respect to the boron concentration in the substrate silicon circumscribing the neighboring layer is 1 × 10 ¹⁵ atoms / cm ³ or less.

According to a fourth aspect of the silicon wafer of the present invention, the increment of the boron concentration in the single crystal silicon layer within 0.5 μm near the interface with the CVD silicon oxide film with respect to the boron concentration in the bulk silicon in contact with the layer is as follows. 1 × 10 ¹⁵ atom
It is characterized by having a CVD silicon oxide film of s / cm ³ or less on one main surface.

A second aspect of the silicon epitaxial wafer of the present invention is a silicon epitaxial wafer having a CVD silicon oxide film
The increment of the boron concentration in the single crystal silicon substrate within 0.5 μm near the interface with the D silicon oxide film with respect to the boron concentration in the substrate silicon in contact with the layer is 1 × 10 ¹⁵ atoms / cm ³ or less. I do.

[0030] In the silicon epitaxial wafer, and effectively suppress the boron contamination in the environment, the boron concentration in the polycrystalline layer is preferably 5 × 10 ¹⁴ atoms / cm ³ or less, more preferably 3 × 10 ¹⁴ atoms / cm ³ or less, most preferably 1 × 10 ¹⁴ atoms / cm ³ or less.

A fifth aspect of the silicon wafer of the present invention is a silicon wafer having a polycrystalline silicon layer on one main surface of a single crystal silicon layer and a CVD silicon oxide film on the polycrystalline silicon layer, The increment of the boron concentration in the layer near the interface having a width of 1 μm including the interface between the polycrystalline silicon layer and the single crystal silicon layer with respect to the boron concentration in silicon circumscribing the layer near the interface is 1 × 10 ¹⁵ atoms / cm ³ or less. The increment of the boron concentration in the polycrystalline silicon layer near the 0.5 μm-wide interface including the interface between the silicon oxide film and the polycrystalline silicon layer with respect to the boron concentration in the polycrystalline silicon circumscribing the neighboring polycrystalline silicon layer is 1 × 10 ¹⁵ atoms / cm
³ or less.

A third aspect of the silicon epitaxial wafer of the present invention is a silicon epitaxial wafer having a polycrystalline silicon layer on the back surface of a substrate and a CVD silicon oxide film on the polycrystalline silicon layer, The increase in the boron concentration in the 1 μm-wide interface near layer including the interface between the silicon layer and the single crystal silicon layer with respect to the boron concentration in silicon circumscribing the interface near layer is 1 × 10 ¹⁵ atoms /
cm ³ or less, boron in the polycrystalline silicon circumscribing the silicon oxide film and a near-near polycrystalline silicon layer of the boron concentration near the interface polycrystalline silicon layer of width 0.5μm including the interface between the polycrystalline silicon layer 1 × 10 ¹⁵ increments for concentration
It is characterized by being at most atoms / cm ³ .

In the above silicon wafer, the concentration of boron in the bulk of single crystal silicon is 1 × 10 ¹⁶ atoms / cm ³
It is particularly effective for the following products:

The above silicon epitaxial wafer is particularly effective for products in which the concentration of boron in the substrate is 1 × 10 ¹⁶ atoms / cm ³ or less.

A first aspect of the method for producing a silicon wafer according to the present invention is characterized in that, in producing the above-described silicon wafer, treatment such as treatment and storage is performed in an atmosphere having a boron concentration of 15 ng / m ³ or less. I do.

The silicon epitaxial wafer of the present invention
The first aspect of the method for manufacturing the silicon epitaxy is
In producing a wafer, the boron concentration is 15
ng / m ^ThreeHandling, storage, etc. should be performed in the following atmosphere.
And features.

According to a second aspect of the method for manufacturing a silicon wafer of the present invention, in manufacturing the above-described silicon wafer, the formation of the polycrystalline silicon layer is performed at a boron concentration of 15 ng / m 2.
It is characterized in that it is performed in an atmosphere of ³ or less.

In a second aspect of the method for producing a silicon epitaxial wafer of the present invention, in producing the above-mentioned silicon epitaxial wafer, the polycrystalline silicon layer is formed in an atmosphere having a boron concentration of 15 ng / m ³ or less. Features.

According to a third aspect of the method for manufacturing a silicon wafer of the present invention, in manufacturing the above-described silicon wafer, the CVD silicon oxide film is formed at a boron concentration of 1%.
It is performed in an atmosphere of 5 ng / m ³ or less.

According to a third aspect of the method for manufacturing a silicon epitaxial wafer of the present invention, in manufacturing the above-described silicon epitaxial wafer, a CVD silicon oxide film is formed in an atmosphere having a boron concentration of 15 ng / m ³ or less. It is characterized by the following.

According to a fourth aspect of the method of manufacturing a silicon wafer of the present invention, in manufacturing the above-described silicon wafer, a polycrystalline layer is formed on the surface of which the amount of attached boron is suppressed to 1 × 10 ¹⁰ atoms / cm ² or less. It is characterized by forming.

In a fourth aspect of the method for manufacturing a silicon epitaxial wafer according to the present invention, in manufacturing the above-described silicon epitaxial wafer, the surface of which the amount of boron deposited is suppressed to 1 × 10 ¹⁰ atoms / cm ² or less is polycrystalline. Forming a layer.

The atmosphere adjusting equipment according to the present invention is characterized in that the concentration of boron in the atmosphere is 15 ng / m ³ or less.

The clean room of the present invention is characterized in that the clean room atmosphere has a boron concentration of 15 ng / m ³ or less.

An air conditioner for a clean room according to the present invention includes an air conditioner having a boron-less filter and a boron adsorption filter, and one or more wafer processing apparatuses having a boron-less filter. It is characterized in that it is configured to circulate between a clean room and the wafer processing apparatus.

In the air conditioner for a clean room,
It is preferable to provide a boronless filter and a boron adsorption filter.

In the air conditioner for a clean room,
Preferably, the internal pressure of the wafer processing apparatus is higher than the internal pressure of the clean room, and the internal pressure of the clean room is adjusted to be higher than the external pressure. Here, the external pressure refers to a pressure in a service room (a room used for changing clothes of workers, carrying in / out of products, etc.) or a corridor adjacent to the outside of the clean room, and is also referred to as outside pressure.

The method of manufacturing a wafer according to the present invention is characterized in that the above-described wafer is manufactured by using the above-mentioned air conditioner for a clean room.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 3 in the accompanying drawings. It goes without saying that various modifications are possible without departing from the scope of the present invention.

FIG. 1 is a flowchart showing a method of manufacturing a silicon epitaxial wafer with a backside PBS film as an example of various silicon wafer manufacturing methods according to the present invention.
FIG. 4 is an explanatory view showing a manufacturing procedure of the epitaxial wafer.

In FIG. 1, reference numeral 100 denotes a silicon wafer manufacturing process which is a substrate for an epitaxial wafer, and a silicon single crystal ingot is processed by a usual method such as slicing, chamfering, lapping, etching, annealing and the like to form a silicon wafer W. Manufactured.

If desired, the silicon wafer W can be taken out at this stage, or one or both sides of the taken-out silicon wafer W can be mirror-polished to obtain a mirror-polished silicon wafer. In the present invention, the washing, drying, and storage (packing) processes after the mirror polishing are carried out at a boron concentration of 15 ng /
The amount of boron adhering to the surface is reduced to 1 × 10 ¹⁰ atoms / cm ² by performing the cleaning in an extremely low clean room of not more than m ^3.
To obtain a silicon wafer free from boron contamination in which the boron concentration in the surface layer up to a depth of 0.5 μm is 1 × 10 ¹⁵ atoms / cm ³ or less with respect to the boron concentration in the bulk silicon immediately below the surface layer Can be.

Reference numeral 102 denotes a PBS film forming step, for example, using a raw material SiH at a vacuum degree of 0.2 to 1 Torr and 600 to 700 ° C.
₄ is disassembled, and polycrystalline silicon is deposited on the substrate silicon wafer to form a PBS film 62 having a thickness of 0.5 to 2 μm.
To form The present invention is characterized in that the PBS film forming step is performed in an extremely low clean room in which the concentration of boron in the atmosphere described below is 15 ng / m ³ or less. Thereby, boron contamination at the interface 70 between the silicon wafer W and the polycrystalline silicon layer (PBS film) 62 can be suppressed.

If desired, the silicon wafer W can be taken out at this stage. In this case, the boron contamination at the interface 70 is suppressed, that is, the boron concentration in the 1 μm-wide interface near layer including the interface between the polycrystalline silicon layer and the single crystal silicon layer is determined by the boron concentration in silicon circumscribing the interface near layer. 1 × 10 ¹⁵ atoms / cm
It is possible to obtain a silicon wafer W provided with a polycrystalline silicon layer 62 of not more than ³ [FIG.
(B)].

One surface of the taken-out silicon wafer W is mirror-polished, and a low-boron-contaminated polycrystalline silicon layer 62 is formed on the back surface.
It is also possible to obtain a mirror-polished silicon wafer provided with. In the obtained silicon wafer W, the boron concentration in the layer near the interface having a width of 1 μm including the interface between the polycrystalline silicon layer and the single crystal silicon layer is increased by 1 × with respect to the boron concentration in the silicon circumscribing the layer near the interface. 10 ¹⁵ atom
It has a polycrystalline silicon layer 62 of s / cm ³ or less on the back surface.

In the present invention, the washing, drying and storage (packing) steps after the mirror polishing are performed in a clean room in which the boron concentration in the atmosphere described below is as low as 15 ng / m ³ or less, so that the surface and the vicinity of the surface can be obtained. A silicon wafer with a polycrystalline silicon layer without boron contamination can be obtained. This obtained silicon wafer W
Is that the boron concentration in at least a part of the polycrystalline silicon layer 62 is 5 × 10 ¹⁴ in addition to the reduction of the boron concentration near the interface between the polycrystalline silicon layer and the single crystal silicon layer.
It has a polycrystalline layer of atoms / cm ³ or less on the back surface.

Reference numeral 104 denotes a CVD silicon oxide film forming step, in which silicon oxide is deposited on the PBS film 62 on the back side of the silicon wafer W using, for example, SiH ₄ and oxygen at 380 to 500 ° C. under atmospheric pressure. And a film thickness of 0.2 to 2
A μm CVD silicon oxide film 64 is formed [FIG.
(C)]. In the present invention, the CVD silicon oxide film forming step will be described later.
It is characterized in that it is performed in an extremely low clean room of g / m ³ or less.

As a result, boron contamination at the interface 72 between the PBS film 62 and the CVD silicon oxide film 64 is suppressed, that is, the vicinity of the 0.5 μm wide polycrystal including the interface between the CVD silicon oxide film and the polycrystalline silicon layer. The increase in the boron concentration in the silicon layer with respect to the boron concentration in the polycrystalline silicon circumscribing the neighboring polycrystalline silicon layer is 1 × 10 ¹⁵
atoms / cm ³ or less.

Here, if necessary, a PBS film forming step 1
02 may be omitted, and the CVD silicon oxide film 64 may be directly formed on the back side of the silicon wafer W according to the method of the present invention. This silicon wafer is CVD
A CVD silicon oxide film in which the increment of the boron concentration in the single crystal silicon layer within 0.5 μm near the interface with the silicon oxide film with respect to the boron concentration in the bulk silicon in contact with the layer is 1 × 10 ¹⁵ atoms / cm ³ or less. On the back.

It is also possible to form an epitaxial wafer by forming an epitaxial layer on this wafer. In this epitaxial wafer, the increment of the boron concentration in the single crystal silicon substrate within 0.5 μm near the interface with the CVD silicon oxide film with respect to the boron concentration in the substrate silicon in contact with the layer is 1 × 10 ¹⁵ atoms / cm ³ or less. There is something.

Reference numeral 106 denotes an epitaxial layer growing step.
After removing the polycrystalline silicon layer 62 on the surface of the silicon wafer W by, for example, mirror polishing (FIG. 2D), the surface of the silicon wafer W having the PBS film 62 and the CVD silicon oxide film 64 on the back surface is, for example, at atmospheric pressure. Lower 1000-12
Flow a mixed gas of SiHCl ₃ and H ₂ at 00 ° C. to a thickness of 3-1.
An epitaxial layer 66 of 5 μm is formed. At this time, if the boron contamination at the interfaces 70 and 72 is suppressed to 1 × 10 ¹⁰ atoms / cm ² or less according to the method of the present invention, the boron diffusion into the PBS film 62 is caused by the boron concentration in the polycrystalline layer. (For example, 3 × 10 ¹⁴ atoms / cm ³ ).

Reference numeral 108 denotes a step of taking out the epitaxial wafer with the back PBS film, and the epitaxial wafer 68 with the back PBS film with the boron contamination suppressed as much as possible can be obtained (FIG. 2E).

Next, an embodiment of a clean room of the present invention and an air conditioner thereof preferably used for producing the silicon wafer and the silicon epitaxial wafer of the present invention will be described with reference to FIG.

This embodiment is shown by way of example, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. In FIG. 3, the same or similar components as those in FIG. 11 are denoted by the same reference numerals, and the description of the configuration and operation will not be repeated.

The clean room air conditioner 12a of the present invention shown in FIG. 3 has exactly the same configuration as the conventional clean room air conditioner 12 shown in FIG. 11 except for the filter configuration. Except for, the description will not be repeated.

The clean room air conditioner 12a of the present invention
Are air filters 16a, 16
16b, 18a, 20a, 20b, 22a, 24a, 2
6a, 28a, 30a, 32a, 34a, 36a, 38
a-less filters 16x, 16y, 18
x, 20x, 20y, 22x, 24x, 26x, 28
x, 30x, 32x, 34x, 36x, 38x,
Further, boron-free medium performance filters 52x and 58x are used in place of the medium performance filters 52 and 58, and the pre-filter 9
8, a boron-less pre-filter 98x and a boron-less roll filter 99x are used in place of the roll filter 99, and a boron adsorption filter 40x is provided downstream of the boron-less medium-performance filter 52x of the external conditioner 40;
The boron adsorption filter 44x is provided downstream of the boron-less medium performance filter 58x.

In the clean room air conditioner 12a of the present invention having the above-described configuration, the outside air is
0, through the impurity removing device 42 and the air conditioner 44, and then to each of the boronless filters 16x, 16y, 18x, 20
x, 20y, 22x, CVD processing chamber 16, CV
D furnace body chamber 18, PBS film formation chamber 20, PBS furnace body chamber 22
Each is introduced inside.

The air introduced into each chamber is supplied to the washer 24 via the boron-less filter 24x, further to the dryer 26 via the boron-less filter 26x, and to the storage clean booth 28 via the boron-less filter 28x. , A clean booth for storage via the boron-less filter 32x, to the dryer 34 via the boron-less filter 34x, to the pre-cleaner 32 via the boron-less filter 32x, to the CVD apparatus 30 via the boron-less filter 32x. 36
And through a boron-less filter 38x into the PBS device 38, and finally discharged into the air discharge space 39.

For example, some of the air is directly exhausted from the cleaning devices 24 and 32, and all of the air is exhausted from the CVD device 30. The air that has reached the air discharge space 39 becomes about 80% of the entire supply amount, returns to the second air pipe 48 through the recovery pipe 43, and is reused.

By using the clean room air conditioner 12a of the present invention as described above, it is possible to set the boron concentration of the atmosphere in the clean room 14 to 15 ng / m ³ or less.

The boronless air filters 16x, 16
Specifically, a boron-free ULPA filter (ATMMF-31-P-B made by Nippon Inorganic Corporation) is used as y, 18x, 20x, 20y, and 22x. Performance filter (manufactured by Nippon Inorganic Co., Ltd., EML-56-9)
0) and a boron-less roll filter 99x (manufactured by Nippon Inorganic Co., Ltd., DSR-340R-TH-C-
2) and the boron adsorption filters 40x, 44x
As a boron adsorption filter (Nippon Inorganic Co., Ltd.,
ACS-31-Q-b) may be used.

[0072]

The present invention will be described below with reference to examples of the present invention.
It goes without saying that these examples are shown by way of example and are not to be construed as limiting.

(Experimental Example 1: Formation of Atmosphere with Boron Concentration of 15 ng / m ³ or Less) The air conditioner for a clean room shown in FIG. 3 (the filters having the product names exemplified as specific examples) were used. 7000m ³
/ hr, the pressure is 20-30 mmH ₂ O with respect to the atmospheric pressure, the air volume of the air conditioner is 37500 m ³ / hr, and the pressure is 2 with respect to the atmospheric pressure.
And 5~35mmH ₂ O of pressure, and a chamber internal pressure of the clean room to an external pressure is set to 3.0~4.0mmH ₂ O higher pressure was measured boron concentration across the filter. As shown in Table 1, the boron concentration in the air after the filter was controlled to 15 ng / m ³ or less. The number of particles in the clean room was 0.

[0074]

[Table 1]

The measurement of the boron concentration in the air was performed as follows. Boron recovery method: ・ Dissolve pure water (air suction method using impinger) ・ Amount of pure water for recovery before sampling --20 ml ・ Amount of pure water recovered after sampling --- about 17.5 ml ・ Aspiration flow ------ −−− 1 liter / min ・ Aspiration time −−−−−−−−− 4hrs ・ Boron analysis method: ICP-MS (inductively coupled plasma mass spectrometry) ・ Equipment --- PLASMATRACE 2 manufactured by MICROMASS, in air The boron concentration was calculated by multiplying the measured value by the measured liquid amount to obtain the mass, and dividing the obtained value by the amount of the sampled gas.

(Example 1: PBS film forming treatment under the atmosphere of Experimental Example 1) <Sample> Silicon wafer, 200 mm in diameter, CZ-P type, 8-1
5Ω · cm, crystal axis <100><PBS film formation process> Pre-cleaning: SC-1 (ammonia, hydrogen peroxide, water) → dilute hydrofluoric acid cleaning → SC-2 (hydrochloric acid, hydrogen peroxide, water) → spin Drying PBS treatment: (temperature) 650 ° C., (time) 3.5 hours,
(Reaction gas) monosilane, (film thickness) 1.2 μm

In the clean room atmosphere of Experimental Example 1 (boron concentration: 4 to 13 ng / m ³ ), the above sample was used to form a PBS film under the above conditions. SIMS (Secondary Ion Mass Spectroscopy,
Secondary ion mass spectrometer: IMS-4F, manufacturer:
The results were shown in FIG.
As is clear from FIG. 4, the boron concentration in the PBS membrane was 1
× 10 ¹⁴ atoms / cm ³ or less, and the boron concentration (approximately 6 × 10 ¹⁴ atoms / cm ³ ) in the layer near the interface having a width of 1 μm including the boundary between the PBS film and the substrate silicon is lower than that of the substrate circumscribing this neighboring layer. Boron concentration in crystalline silicon (about 1 × 10 ¹⁵ at
oms / cm ³ ) (the increment is minus) and the boron concentration in the circumscribed PBS layer (about 1 × 10 ¹⁴ atoms / cm ³ )
In contrast, the difference is 5 × 10 ¹⁴ atoms / cm ³ .

Comparative Example 1: PB in Conventional Atmosphere
S film formation) Under conventional atmosphere (boron concentration 50-80 ng / m
^{In 3} ), the same sample as in Example 1 was used, and a PBS film was formed under the same conditions. The measurement of the boron concentration in the sample was performed in the same manner as in Example 1, and the results are shown in FIG. The difference between the boron concentration distributions in FIGS. 4 and 5 shows the effect of boron contamination based on the difference in the boron concentration in the atmosphere. In FIG. 5, the boron concentration in the PBS film rapidly increases near the interface. The maximum value is about 6 × 10 ¹⁶ atoms / cm ³ , and the boron layer in the layer near the interface having a width of 1 μm including the boundary between the PBS layer and the substrate silicon has a boron concentration of about 3 × 10 ¹⁶ atoms / cm ³ circumscribing the PBS layer. And the increase in concentration for silicon single crystals is much more than 1 × 10 ¹⁵ atoms / cm ³ .

(Example 2: PBS film formation + CVD treatment in the atmosphere of Experimental Example 1) <Sample> Silicon wafer, diameter 200 mm, CZ-P type, 8-1
5Ω · cm, crystal axis <100><PBS film formation process> Pre-cleaning: SC-1 (ammonia, hydrogen peroxide, water) → dilute hydrofluoric acid cleaning → SC-2 (hydrochloric acid, hydrogen peroxide, water) → spin Drying PBS film formation: (temperature) 650 ° C., (time) 3.5 hours, (reaction gas) monosilane, (film thickness) 1.2 μm

<CVD process> Pre-cleaning: SC-1 (ammonia, hydrogen peroxide, water) → dilute hydrofluoric acid cleaning → SC-2 (hydrochloric acid, hydrogen peroxide, water) → spin drying CVD process: (temperature) 430 ° C., (time) 10 minutes, (reaction gas) monosilane, enzyme, (film thickness) 0.3 μm <Epitaxial process> Pre-cleaning: SC-1 (ammonia, hydrogen peroxide, water) → S
C-2 (hydrochloric acid, hydrogen peroxide, water) → IPA drying Epitaxial treatment: (temperature) 1100 ° C., (hour) 1
0 min, (reaction gas) hydrogen trichlorosilane, (film thickness) 5.0 μm

In the clean room atmosphere of Experimental Example 1 (boron concentration: 4 to 13 ng / m ³ ), a PBS film and a CVD silicon oxide film were formed using the above sample under the above conditions, and then an epitaxial film was grown. Was. After the CVD silicon oxide film on the back surface was dissolved and removed with a 20% HF solution, the boron concentration in the sample PBS film and the substrate single crystal silicon was measured in the same manner as in Example 1, and the results are shown in FIG. .

As is clear from FIG. 6, it is recognized that boron diffuses from the substrate single crystal silicon into the PBS film due to heating during the formation of the epitaxial film.
The boron concentration between the 1 μm width including the boundary between the S film and the substrate single crystal silicon is about 6 × 10 ¹⁴ atoms / cm ³ ,
The increment is smaller than 1 × 10 ¹⁵ atoms / cm ^{3 with} respect to the boron concentration in the S film (about 1 × 10 ¹⁴ atoms / cm ³ ), and the boron concentration in the circumscribed single crystal silicon (about 1 × 10 ¹⁵ atoms / cm ³ ). at
oms / cm ³ ), which confirms that the level of boron contamination during wafer processing is kept low.

(Comparative Example 2: PB in Conventional Atmosphere)
S film formation + CVD treatment in the atmosphere of Experimental Example 1) In a conventional atmosphere (boron concentration of 50 to 80 ng / m ³ ), PB was formed under the same conditions using the same sample as in Example 2.
An S film was formed, and then a CVD silicon oxide film was formed under the same conditions as in Example 2 under a clean room atmosphere (boron concentration: 4 to 13 ng / m ³ ) of Experimental Example 1, and then an epitaxial film was grown. went. After the CVD silicon oxide film on the back surface was dissolved and removed with a 20% HF solution, the boron concentration in the sample PBS film and the substrate single crystal silicon was measured in the same manner as in Example 1, and the results are shown in FIG. .

As is clear from FIG. 7, before the PBS film forming process, boron in the atmosphere adheres to the surface of the sample substrate single crystal silicon wafer, and this is heated in the epitaxial film to form in the PBS film and the substrate single crystal silicon wafer. The boron concentration in the layer near the interface having a width of 1 μm including the boundary between the PBS film and the substrate single-crystal silicon diffuses into the crystalline silicon, and the average boron concentration is about 3 ×.
The average boron concentration in the substrate single crystal silicon circumscribed at 10 ¹⁶ atoms / cm ³ is about 1.2 × 10 ¹⁵ atoms / cm ^3, and is significantly larger than the average boron concentration 1 × 10 ¹⁶ atoms / cm ³ in the circumscribed PBS film. Shows a high value.

The PBS film has a thickness of 0 μm, ie,
The boron concentration at the boundary with the silicon oxide film is 4 × 10 ¹⁴ at
As a result of suppressing the boron concentration in the atmosphere at the stage of forming the CVD silicon oxide film to 15 ng / m ³ or less at oms / cm ³ , PB
It is shown that is suppressed to a value close to the boron concentration ^{1 × 10 1 4 atoms / cm} 3 in the S film.

(Comparative Example 3: Formation of PBS film in atmosphere of Experimental Example 1 + CVD treatment in conventional atmosphere) In a clean room atmosphere of Experimental Example 1 (boron concentration of 4 to 13)
ng / m ³ ), using the same sample as in Example 2 and forming a PBS film under the same conditions, and then under a conventional atmosphere (boron concentration 50 to 80 ng / m ³ ), A CVD silicon oxide film was formed under the same conditions, and then an epitaxial film was grown. After dissolving and removing the backside CVD silicon oxide film with a 20% HF aqueous solution, the measurement of the boron concentration in the sample PBS film and the substrate single crystal silicon was performed in the same manner as in Example 1, and the results are shown in FIG.

As is apparent from FIG. 8, the boron concentration is high.
Boron adhering to the atmosphere is a PBS film and CVD silicon
In the PBS film from the side of the oxide film interface (0 μm depth in the figure)
And the average concentration of boron up to a depth of 0.5 μm is 2
× 10^Fifteenatoms / cm^ThreeAnd a high value, and a depth of 0.5 μm or less
Average concentration of boron in the PBS membrane above is about 8 × 10¹⁴atoms /
cm^ThreeHas increased significantly. On the other hand, PBS film formation
The concentration of boron in the atmosphere is 15 ng / cm^ThreeState below
At the boundary between the PBS film and the substrate single-crystal silicon.
The average concentration of boron in a width of 1 μm is about 1.5 × 1
0^Fifteenatoms / cm^ThreeIn the circumscribed single-crystal silicon.
Ron average concentration (about 2 × 10^Fifteenatoms / cm ^Three) To the following value
Is suppressed.

That is, the amount of boron adhering to the surface of the substrate single crystal silicon is so small that it hardly affects the predetermined boron concentration, and the boron diffused from this interface into the PBS film is also contained in the film at the time of forming the PBS film. It is known that it hardly affects boron concentration.

(Comparative Example 4: PB in Conventional Atmosphere)
S film formation + CVD treatment) Under conventional atmosphere (boron concentration 5
0-80 ng / m ³ ), using the same sample as in Example 2, forming a PBS film under the same conditions, and then performing CVD under the same conditions as in Example 2 under the conventional atmosphere. A silicon oxide film was formed, and then an epitaxial film was grown. 20% H on backside CVD silicon oxide film
After being dissolved and removed with an aqueous F solution, the concentration of boron in the sample was measured in the same manner as in Example 1, and the results are shown in FIG.

As is clear from FIG. 9, the boron concentration in the PBS film is determined by the diffusion of the deposited boron from the boundary between the PBS film and the substrate single crystal silicon, the CVD silicon oxide film and the PBS.
Due to the diffusion of the attached boron from the interface with the film (depth: 0 μm in the figure), the value is higher than that of FIGS. 7 and 8 by about one digit or more. Average concentration of boron between 1 μm width (about 4 × 1
0 ¹⁵ atoms / cm ³ ) increases by about 2.5 × 10 ¹⁵ atoms / cm ³ compared to the average concentration of boron in the circumscribed substrate single crystal silicon (about 1.5 × 10 ¹⁵ atoms / cm ³ ). ing.

As is clear from the above Examples and Comparative Examples, the boron concentration in the PBS film formed by suppressing the boron concentration in the atmosphere to 15 ng / m ³ or less is at least 3 × in at least a part of the film. It is known that it is 10 ¹⁴ atoms / cm ³ or less.

4 to 9, the vertical line at the center is the interface, the left side of the interface is the PBS film, and the right side is the substrate single crystal silicon. 7, 8 and 9, the reference numeral 120 indicates
Indicates the boron diffusion direction in the epitaxial layer growth step.

(Comparative Example 5) Conventional clean room air conditioner shown in FIG. 11 (external air conditioner roll filter: AT-200-KS manufactured by Nippon Inorganic Co., Ltd., medium external air filter):
ASTC-56-95 made by Nippon Inorganic Co., Ltd., air conditioner pre-filter: DS-600-31-R made by Nippon Inorganic Co., Ltd.
EA-20, medium-performance air conditioner filter: ASTC-56-95 manufactured by Nippon Inorganic Corporation, ULPA in a clean room:
Using NMO-320 manufactured by Nippon Inorganic Co., Ltd., the air pressure of the external controller was 7000 m ³ / hr and the pressure was 10 to 2 with respect to the atmospheric pressure.
0 mm H ₂ O under pressure, the pressure is 3.0 to the chamber internal pressure of the pressurized state and clean room 15~25mmH ₂ O to external pressure to atmospheric pressure in air volume 37500m ³ / hr of air conditioner
The pressure was set high at 4.0 mmH ₂ O, and the boron concentration in the air before and after the filter was measured in the same manner as in Example 1. The results are shown in Table 2.

As is clear from the results in Table 2, according to the conventional equipment, the concentration of boron in the air after filtering was 15 ng / m 2.
It was impossible to control below ³ . The number of particles in the clean room was 0. Further, when the wafer was processed in this clean room atmosphere, the concentration of boron adsorbed on the wafer was 1 × 10 ¹⁵ atoms /
It was not possible to reduce it to cm ³ or less.

[0095]

[Table 2]

(Experimental Example 2) After pre-cleaning was performed on the same silicon wafer as in Example 2 under the same conditions, a clean room (relative humidity: 30 to 50%, temperature: 25 ° C. ± 3)
° C, pressure: external pressure + 3-5mmAq, boron concentration: 60ng / m
³ ) SIMS (apparatus: IMS-4) was used to determine the relationship between the standing time when left for 2 hours and the amount of attached boron on the wafer surface.
F, manufacturer: Camecame of France) and shown in FIG. As is clear from FIG. 12, it was confirmed that when the standing time exceeded 1 hour, the amount of attached boron became saturated.

(Experimental Example 3) An experimental example was set up in a clean room under the same conditions as the atmosphere of Experimental Example 2 except that the boron concentration in the indoor atmosphere was changed to four steps of 5, 10, ³⁰ , and 60 ng / m3. The same wafer as in No. 2 was left for 2 hours, and the amount of boron attached to the wafer surface (atoms / c
m ² ) was measured using SIMS in the same manner as in Experimental Example 2, and the relationship between the two was quantitatively grasped as shown in FIG. As clearly shown in FIG. 13, when the boron concentration in the environmental atmosphere was set to 15 ng / m ³ or less, it was found that the amount of boron attached to the wafer surface was suppressed to 1 × 10 ¹⁰ atoms / cm ² or less.

In the above Examples and Comparative Examples, a p-type silicon wafer doped with boron at a relatively low concentration was used. However, the present invention is not limited to this, and n-type silicon doped with phosphorus, arsenic, antimony, etc. The present invention is effective for a wafer.

[0099]

As described above, in the silicon wafer and the silicon epitaxial wafer of the present invention, the surface, the PBS film, the substrate single crystal silicon, the PBS film and the CVD
Since the amount of boron contamination at the interface between the silicon oxide film and the substrate single crystal silicon and the epitaxial layer is suppressed to a predetermined concentration or less, the effect of stabilizing quality and not adversely affecting device characteristics is achieved. .

According to the method for manufacturing a silicon wafer and the method for manufacturing a silicon epitaxial wafer of the present invention,
There is an advantage that the silicon wafer and the silicon epitaxial wafer having stable quality of the present invention can be manufactured inexpensively and efficiently.

According to the atmosphere adjusting equipment and the clean room of the present invention, the boron concentration in the atmosphere and the clean room atmosphere is controlled to a desired concentration or less, so that the adhesion of boron to the wafer can be suppressed to an extremely low level. Further, according to the air conditioner for a clean room of the present invention, the boron concentration in the clean room atmosphere can be significantly reduced, and various silicon wafers or epitaxial wafers with reduced contamination by boron can be stably produced. Is achieved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for manufacturing a silicon wafer and a silicon epitaxial wafer according to the present invention.

FIG. 2 is an explanatory view showing a production procedure of a silicon wafer and a silicon epitaxial wafer according to the present invention;
Is a silicon wafer, (b) is a state where a polycrystalline silicon layer is formed on the silicon wafer, (c) is a CVD silicon oxide film on the polycrystalline silicon layer (PBS film) on the back surface of the silicon wafer of (b). Formed state, (d)
(E) shows a state where the polycrystalline silicon layer on the surface of the silicon wafer is removed, and (e) shows a state where an epitaxial layer is formed on the surface of the silicon wafer from the state of (d).

FIG. 3 is a schematic explanatory view showing a clean room air conditioner of the present invention.

FIG. 4 is a graph showing the concentration of boron in the sample in the depth direction of the sample in Example 1.

FIG. 5 is a graph showing the concentration of boron in a sample in the depth direction of the sample in Comparative Example 1.

FIG. 6 is a graph showing the concentration of boron in a sample in the depth direction of the sample in Example 2.

FIG. 7 is a graph showing the boron concentration in the sample in the depth direction of the sample in Comparative Example 2.

FIG. 8 is a graph showing the concentration of boron in a sample in the depth direction of the sample in Comparative Example 3.

FIG. 9 is a graph showing the concentration of boron in a sample in the depth direction of the sample in Comparative Example 4.

FIG. 10 is an explanatory view showing a conventional procedure for manufacturing a silicon wafer and a silicon epitaxial wafer.
Is a silicon wafer, (b) is a state where a polycrystalline silicon layer is formed on the silicon wafer, (c) is a CVD silicon oxide film on the polycrystalline silicon layer (PBS film) on the back surface of the silicon wafer of (b). Formed state, (d)
(E) shows a state where the polycrystalline silicon layer on the surface of the silicon wafer is removed, and (e) shows a state where an epitaxial layer is formed on the surface of the silicon wafer from the state of (d).

FIG. 11 is a schematic explanatory view showing an example of a conventional clean room air conditioner.

FIG. 12 is a graph showing a relationship between a wafer standing time and a wafer boron adhesion amount in Experimental Example 2.

FIG. 13 is a graph showing the relationship between the boron concentration in the environmental atmosphere and the amount of attached boron on the silicon wafer surface in Experimental Example 3.

[Explanation of symbols]

12, 12a: air conditioning equipment, 14: clean room, 1
6: CVD processing chamber, 18: CVD furnace body chamber, 20: PBS
Film formation chamber, 22: PBS furnace body chamber, 24: Cleaning machine before CVD treatment, 26: Dryer, 28: Clean booth for storage, 3
0: CVD apparatus, 32: PBS film forming pre-cleaner, 34:
Dryer, 36: clean booth for storage, 38: PBS device, 39: space for air discharge, 40: outside air conditioner, 42: impurity removal device, 43: collection pipe, 44: air conditioner, 46:
First air pipe, 48: Second air pipe, 50: Third air pipe, 52, 58: Medium performance filter, 54, 56:
Fans, 16a, 16b, 18a, 20a, 20b, 2
2a, 24a, 26a, 28a, 30a, 32a, 34
a, 36a, 38a: air filter, 16x, 16y,
18x, 20x, 20y, 22x: boronless air filter, 52x, 58x: boronless medium performance filter, 4
0x, 44x: boron adsorption filter, 62, 62a: P
BS film, 64: CVD silicon oxide film, 66: epitaxial layer, 68, 68a: epitaxial wafer with backside PBS film, 70, 72: interface, 98: prefilter, 99: roll filter, 99x: boronless roll filter, 100: silicon wafer manufacturing process, 10
2: PBS film forming step, 104: CVD film forming step, 1
06: epitaxial layer growth step, 108: backside PBS
The film is an epitaxial wafer take-out step, 120: diffusion direction of boron into the PBS film in the epitaxial film growth step, W: silicon wafer.

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 000190149 Shin-Etsu Semiconductor Co., Ltd. 1-4-2 Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Naoki Naito Ogokura, Ogokura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture 150 Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa Research Laboratory (72) Inventor Fumiaki Maruyama 2174-1, Hotada, Gunma-cho, Gunma-gun, Gunma Prefecture Semiconductor Division, Mimasu Semiconductor Industry Co., Ltd. (72) Inventor Atsuo Uchiyama 1393, Yashiro, Yashiro, Nagano Prefecture Nagano Electronics Industrial Co., Ltd. In company

Claims (26)

[Claims] 1. The amount of boron attached to a surface is 1 × 10 ¹⁰ atom
A silicon wafer having a s / cm ² or less. 2. The silicon according to claim 1, wherein the increment of the boron concentration in the surface layer up to a depth of 0.5 μm with respect to the boron concentration in the bulk silicon immediately below the surface layer is 1 × 10 ¹⁵ atoms / cm ³ or less. Wafer. 3. The method according to claim 1, wherein the boron concentration in the 1 μm wide interface layer including the interface between the polycrystalline silicon layer and the single crystal silicon layer is 1 × 10 ¹⁵ atoms / increment with respect to the boron concentration in silicon circumscribing the interface layer. A silicon wafer having a polycrystalline layer having a size of cm ³ or less on one main surface. 4. A silicon epitaxial wafer having a polycrystalline silicon layer on a back surface of a single crystal silicon substrate, wherein the boron concentration in a 1 μm-wide interface vicinity layer including an interface between the single crystal silicon and the polycrystalline silicon layer of the substrate is reduced. A silicon epitaxial wafer, wherein an increment with respect to a boron concentration in substrate silicon circumscribing the adjacent layer is 1 × 10 ¹⁵ atoms / cm ³ or less. 5. The vicinity of an interface with a CVD silicon oxide film.
The increment of the boron concentration in the single crystal silicon layer within 5 μm to the boron concentration in the bulk silicon in contact with the layer is 1 ×
A silicon wafer having a CVD silicon oxide film of 10 ¹⁵ atoms / cm ³ or less on one main surface. 6. A silicon epitaxial wafer having a CVD silicon oxide film on the back surface of a substrate, wherein the silicon epitaxial wafer has a CV
The increment of the boron concentration in the single crystal silicon substrate within 0.5 μm near the interface with the D silicon oxide film with respect to the boron concentration in the substrate silicon in contact with the layer is 1 × 10 ¹⁵ atoms / cm ³ or less. Silicon epitaxial wafer. 7. The silicon wafer according to claim 3, wherein a polycrystalline layer having a boron concentration of at least part of the polycrystalline layer of 5 × 10 ¹⁴ atoms / cm ³ or less is provided on the back surface. 8. The silicon epitaxial wafer according to claim 4, further comprising a polycrystalline layer having a boron concentration of at least part of the polycrystalline layer of 5 × 10 ¹⁴ atoms / cm ³ or less on the back surface. 9. A single-crystal silicon layer having one main surface formed of polycrystal
CVD silicon acid on the silicon layer and the polycrystalline silicon layer
Silicon wafer having a nitride film
1 μm wide interface including interface between silicon layer and single crystal silicon layer
Circumscribes the boron concentration in the neighboring layer
1 × 10 increments for boron concentration in silicon^Fifteenatom
s / cm^ThreeThe following is the silicon oxide film and polycrystalline silicon
Polycrystalline silicon near the interface with a width of 0.5μm including the interface with the layer
Circumscribes the surrounding polycrystalline silicon layer with a boron concentration in the layer
The increment for the boron concentration in polycrystalline silicon is 1 × 10
^Fifteenatoms / cm^ThreeA silicon wafer characterized by the following:
-Ha. 10. A silicon epitaxial wafer having a polycrystalline silicon layer on a back surface of a substrate and a CVD silicon oxide film on the polycrystalline silicon layer, the width being 1 μm including an interface between the polycrystalline silicon layer and the single crystal silicon layer. The increase in the boron concentration in the layer near the interface with respect to the boron concentration in silicon circumscribing the layer near the interface is 1 × 10 ¹⁵ atoms /
cm ³ or less, boron in the polycrystalline silicon circumscribing the silicon oxide film and a near-near polycrystalline silicon layer of the boron concentration near the interface polycrystalline silicon layer of width 0.5μm including the interface between the polycrystalline silicon layer 1 × 10 ¹⁵ increments for concentration
A silicon epitaxial wafer characterized by being at most atoms / cm ³ . 11. The silicon according to claim 1, wherein the concentration of boron in the bulk of the single crystal silicon is 1 × 10 ¹⁶ atoms / cm ³ or less. Wafer. 12. The method according to claim 1, wherein the concentration of boron in the substrate is 1 × 10 ¹⁶ at.
9. An oms / cm ³ or less.
11. The silicon epitaxial wafer according to any one of claims 10 and 10. In producing the silicon wafer according to any one of claims 1 to 3, 5, 9 and 11,
A method for producing a silicon wafer, wherein the silicon wafer is treated and stored in an atmosphere having a boron concentration of 15 ng / m ³ or less. 14. In manufacturing the silicon epitaxial wafer according to any one of claims 4, 6, 8, 10 and 12, processing and storing the silicon epitaxial wafer in an atmosphere having a boron concentration of 15 ng / m ³ or less. And a method for producing a silicon epitaxial wafer. 15. The method of manufacturing a silicon wafer according to claim 3, wherein the polycrystalline silicon layer is formed in an atmosphere having a boron concentration of 15 ng / m ³ or less. Silicon wafer manufacturing method. 16. In manufacturing the silicon epitaxial wafer according to claim 4, the polycrystalline silicon layer is formed at a boron concentration of 15%.
A method for producing a silicon epitaxial wafer, wherein the method is performed in an atmosphere of ng / m ³ or less. 17. The method according to claim 5, 9 or 11.
In manufacturing the described silicon wafer, CVD
Boron concentration of 15 ng / m for recon oxide film formation ^ThreeThe following mood
Silicon wafer manufacturing method characterized by performing in an atmosphere
Law. 18. The method according to claim 6, wherein
In manufacturing the silicon epitaxial wafer described in the above item, the CVD silicon oxide film is formed with a boron concentration of
A method for producing a silicon epitaxial wafer, wherein the method is performed in an atmosphere of 15 ng / m ³ or less. 19. A polycrystalline layer is formed on the surface of the silicon wafer according to any one of claims 3, 7, 9 and 11, wherein the amount of attached boron is suppressed to 1 × 10 ¹⁰ atoms / cm ² or less. Forming a silicon wafer. 20. In manufacturing the silicon epitaxial wafer according to any one of claims 4, 8, 10 and 12, a polycrystal is formed on the surface where the amount of boron deposited is suppressed to 1 × 10 ¹⁰ atoms / cm ² or less. A method for producing a silicon epitaxial wafer, comprising forming a layer. 21. Atmosphere adjusting equipment wherein the boron concentration in the atmosphere is 15 ng / m ³ or less. 22. A clean room wherein the concentration of boron in the atmosphere is 15 ng / m ³ or less. 23. An air conditioner having a boronless filter and a boron adsorption filter, and an air conditioner having a boronless filter.
Alternatively, an air conditioner for a clean room, comprising a plurality of wafer processing apparatuses, wherein the atmosphere gas is configured to circulate between the air conditioner, the clean room, and the wafer processing apparatus. 24. The air conditioner for a clean room according to claim 23, further comprising a boronless filter and a boron adsorption filter. 25. The internal pressure of the wafer processing apparatus is higher than the internal pressure of the clean room, and the internal pressure of the clean room is adjusted to be higher than the external pressure.
4. The air conditioner for a clean room according to 4. 26. A method for producing a wafer according to any one of claims 1 to 12, wherein the production is performed by using the air conditioner for a clean room according to any one of claims 23 to 25. Method.