JP2001102342A - Manufacturing method of semiconductor device and surface-treating apparatus for semiconductor substrate suitable for manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an extremely simple method of a semiconductor device, that can suppress advance of boron to a semiconductor wafer, and a suitable surface-treating device of a semiconductor wafer using the method. SOLUTION: In this method for manufacturing a semiconductor device, boron elution effect by hot water is utilized, the exposure surface of a semiconductor substrate is surface-treated by the hot water being separated from boron, before the semiconductor substrate that does not contain the boron is heat-treated, and the advance of the boron to the semiconductor substrate is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device and a surface treatment apparatus for a semiconductor substrate suitable for use in the method. The present invention relates to a method for manufacturing a semiconductor device for reducing the amount of B contamination, and a semiconductor substrate surface treatment apparatus suitable for use in the method.

[0002]

2. Description of the Related Art First, a conventional method for manufacturing a semiconductor device will be described with reference to FIGS.

In the following description, a Si wafer will be described as a semiconductor substrate, and a method of forming an impurity diffusion layer on a Si wafer will be described as a method of manufacturing the semiconductor device.

FIG. 6 shows a typical manufacturing flow for forming an impurity diffusion layer of a conventional semiconductor device, FIG. 7 is a schematic view showing the behavior of a boron compound in heat treatment, and FIG. 8 shows an impurity profile. A is a normal profile, and FIG. B is a profile when B is mixed.

In a typical method of manufacturing a semiconductor device according to the prior art, a P-type Si material as a semiconductor material shown in FIG.
On the surface of the wafer 1, as shown in FIG. 6A, to form a thermal oxide film 2 of SiO _2. Next, an opening 4 is formed with a resist 3 by a photolithographic technique, and using the resist 3 as a mask, wet etching or reactive ion etching (= RIE: REACTIVE ION ECTHING)
The opening 4 is opened in the thermal oxide film 3 by means of (FIG. 6C). Then, as shown in FIG. 6D, after the resist 3 is peeled off, an impurity which is a solid source is implanted into the Si wafer 1 to form an N-type impurity layer 5 (FIG. 6E).

In this case, what is problematic is the standing time from the state of the step shown in FIG. 6C to the state of the step shown in FIG. 6E. Such an operation is performed in a clean room. In the clean room, an ULPA filter is generally used in order to collect air dust, but B ₂ O ₃ is a large component in the ULPA filter. include. This B ₂ O ₃ easily reacts with H ₂ O and HF, and exists in the clean room in the following form.

[0007] _{B 2 O 3 + 6HF ⇒2BF 3} + 3H 2 O B 2 O 3 + 6H 2 O⇒2B (OH) 3 + 3H 2 O The BF ₃ or B (OH) ₃ is of Figure 6E from the work in the step of FIG. 6C When the film adheres to the surface of the Si wafer 1 until the operation in the process, as shown in FIG. 7, the following reaction during the heat treatment of FIG. 6E causes a high vapor pressure adhered to the surface of the Si wafer 1. The boron compound is produced as B ₂ O ₃ . When the B ₂ O ₃ reaches the surface of the opposite Si wafer 1, SiO ₂ is generated by a reaction with Si.
At that time, B generated as a by-product is introduced into the Si wafer 1.

Reference numeral 101 denotes a heat treatment reaction tube, and reference numeral 102 denotes a heater disposed on the outer peripheral surface of the heat treatment reaction tube 101.

BF ₃ + O ₂ ⇒B ₂ O ₃ B (OH) ₃ ⇒B ₂ O ₃ (300 ° C. or higher) B ₂ O ₃ + Si⇒SiO ₂ + B The N-type impurity layer in the Si wafer 1 has a P-type impurity. B
Have entered due to the above-mentioned phenomenon, and what should otherwise be the impurity profile shown in FIG. 8A becomes the impurity profile shown in FIG. 8B, and the electrical characteristics of the semiconductor fluctuate. The characteristic fluctuation becomes worse depending on the amount of B entering the Si wafer 1.

[0010]

Therefore, it is required to suppress the adhesion of the boron compound to the Si wafer 1, and various techniques have been proposed for that purpose. Some of the techniques are disclosed in the following published patent publication, Japanese Patent Application Laid-Open No. 04-9751.
7, JP-A-05-57136, JP-A-10-32172
Published in.

The invention disclosed in Japanese Patent Application Laid-Open No. H04-97517, entitled "Method of Manufacturing Semiconductor Device" discloses a method in which the surface of a Si wafer to which B is adhered is exposed to the atmosphere before vapor-phase growth of Si is performed. Is adsorbed with fluorine (F) to combine B and F, and this is heated to 100 to 150 ° C. in a vacuum to gasify and fly off, and then removed.
This is a technique for growing i in a vapor phase.

However, in this technique, it is also necessary to remove B before thermal oxidation and annealing, and it is not possible to remove B diffused in Si at a stage before performing vapor phase growth.

The invention disclosed in Japanese Patent Application Laid-Open No. 05-57136, entitled "Air cleaning method and high-purity silicon filter" discloses a method in which a Si substrate or silicon cleaving equivalent to a Si wafer being manufactured is provided in front of a normal HEPA filter or ULPA filter. By providing a filter that forms a minute gap through which air passes into the clean room, a gas such as P or B existing in the air on the high-purity active silicon surface of the Si substrate or the silicon cleavage piece. The gaseous molecules (impurities) that cannot be removed by the HEPA filter or the ULPA filter are adsorbed and removed by the high-purity silicon filter, and ordinary fine particles are removed by the HEPA filter or the ULPA filter. To supply clean air to the clean room, Is a technique that is subjected to a heat treatment on the surface.

[0014] However, this technique has a problem that not only does the equipment cost rise and the product cost of the semiconductor device rebounds, but also that contaminants such as B already adhered to the surface of the essential Si wafer cannot be removed.

The invention disclosed in Japanese Patent Application Laid-Open No. 10-32172, entitled "Method of Manufacturing Semiconductor Device", cleans a Si wafer using a chemical solution having a low B content, and removes the atmosphere during the cleaning and drying of the Si wafer. This is a technique for performing epitaxial growth after cleaning and drying a Si wafer in a clean bench equipped with a chemical filter having a B adsorption ability in order to suppress B contamination.

However, there is a problem that the technology of removing B is also complicated and the product cost of the semiconductor device increases.

SUMMARY OF THE INVENTION Accordingly, the present invention is to solve these problems, and an extremely simple method of manufacturing a semiconductor device capable of suppressing the intrusion of boron into a semiconductor wafer by utilizing the boron elution effect of warm water and a method of manufacturing the same. It is an object of the present invention to obtain a semiconductor wafer surface treatment apparatus suitable for use.

[0018]

Therefore, in the method of manufacturing a semiconductor device according to the present invention, before heat treatment of a semiconductor substrate not containing boron, the exposed surface of the semiconductor substrate is surface-treated with hot water isolated from boron. The problem has been solved by adopting a method.

In the apparatus for treating a surface of a semiconductor substrate according to the second aspect of the present invention, a loader, a hot water treatment tank, a drying tank, and an unloader are sequentially disposed below, and are disposed so as to be able to traverse above them. The above-mentioned problem is solved by arranging and constructing a transferred device and a chemical filter so as to further cover them.

Therefore, according to the method of manufacturing a semiconductor device of the present invention, B adhering to the exposed surface of the semiconductor substrate before the heat treatment can be easily cleaned with an extremely inexpensive chemical solution.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, a method for manufacturing a semiconductor device according to a preferred embodiment of the present invention and a surface treatment apparatus for a semiconductor substrate (hereinafter simply referred to as “surface treatment apparatus”) suitable for use in the method will be described. Will be described.

FIG. 1 is a flow chart for manufacturing a semiconductor device according to the present invention.
FIG. 2 is a schematic cross-sectional view of a hot water treatment tank suitable for use in the method of manufacturing a semiconductor device of the present invention, FIG. 3 is a graph showing the effect of removing boron by hot water treatment, and FIG. 4 is a surface of an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of the processing apparatus, and FIG. 5 is a graph showing the amounts of boron adhering to the Si wafer before and after the hot water treatment when left in the product storage box for a long time.

First, a method of manufacturing a semiconductor device according to the present invention will be described with reference to FIG.

In the processing steps shown in FIG. 1, the processing steps shown in FIGS. A to D are the same as the processing steps shown in FIGS. 6A to 6D of the prior art. The same processing is performed. Therefore, these processes are omitted here.

FIG. 1D shows a method of manufacturing a semiconductor device according to the present invention.
Is characterized in that a hot water treatment step as shown in FIG. 1Da is provided after the treatment step. In this step, the boron compound generated on the exposed surface can be removed by subjecting the Si wafer 1 obtained in step D to hot water treatment.

A hot water treatment tank 20 for performing this hot water treatment
Is conceptually shown in FIG. In this hot water treatment tank 20,
The plurality of Si wafers 1 obtained in the step D are held parallel to each other at equal intervals, and the processing liquid L is filled so that the Si wafers 1 can be flooded.

As the processing liquid L, the physical property that the boron compound generated on the exposed surface of the Si wafer 1 in the processing step of FIG.
Use pure water heated above 0 ° C.

As described above, the Si wafer 1 having S ₂ O ₃ adhered to the exposed surface is subjected to the hot water treatment in the hot water treatment tank 20 for a predetermined time, so that, as shown in FIG. The amount of the compound attached can be reduced.

Next, referring to FIG.
Surface treatment apparatus 100 according to an embodiment of the present invention in which
Will be described.

The surface treatment apparatus 100 includes a loader 10
The hot water treatment tank 20, the drying tank 30, the unloader 40, the work area 50, the transfer device 60, and the chemical filter 70, and the loader 10, the hot water treatment tank 20, the drying tank 30, the unloader 40, a work area 50 is provided, and a transfer device 60 is further provided above them.
A chemical filter 70 is provided so as to cover these components.

Next, the operation of the surface treatment apparatus 100 will be described.

The Si wafer 1 obtained in the processing step shown in FIG. 1D, transported and placed on the loader 10 is transferred and accommodated in the hot water treatment tank 20 by the transfer unit 60, and is processed there for a predetermined processing time. Perform hot water treatment. After the completion of the hot water treatment, the Si subjected to the hot water treatment from the hot water treatment tank 20 by the transfer unit 60 again.
The wafer 1 (hereinafter, this Si wafer is referred to as a Si wafer 1A) is taken out, transferred to the next drying tank 30, and dried. As a drying method, a spin dryer method is employed, but there is no particular limitation, and an IPA drying method or the like may be used. After the drying process is completed, the dried Si wafer 1A is transferred from the drying tank 30 to the unloader 40 by the transfer device 60, and stored in a product storage box (not shown) by a worker in the work area 50. You.

The ventilation to the surface treatment apparatus 100 is performed throughout the day through the chemical filter 70. As a result, B is removed from the environment in the surface treatment apparatus 100. After removing B ₂ O ₃ adhered to the surface of the Si wafer 1, the environment is removed.
The i-wafer 1A is not re-contaminated in the atmosphere in the surface treatment apparatus 100.

FIG. 5 shows the amount of boron adhering when left in the product storage box for a long time as described above, before and after hot water treatment. As can be seen from FIG. 5, if the boron compound is not contained in the material of the product storage box, even if the Si wafer 1A subjected to the hot water treatment for a long time is stored in the product storage box, the product storage It can be seen that contamination in the box can be prevented.

Therefore, after the processing step of FIG. 1D, a hot water treatment (FIG. 1Da), which is a feature of the present invention, is performed, and then the hot water treated and stored Si wafer 1A is taken out of the product storage box. 1E (FIG. 6E), the N-type impurity is removed from the S by the impurity diffusion device.
The N-type impurity layer 5 is formed by diffusing from the selected surface of the i-wafer 1A. In this manner, a semiconductor device having stable semiconductor electrical characteristics with a profile as shown in FIG. 8A can be obtained.

Although pure water has been described as the processing liquid L in the hot water processing tank 20, the processing liquid L may be ammonia-hydrogen peroxide or hydrochloric acid-hydrogen in addition to pure water.

When an ion exchange resin is used for the chemical filter 70, the B capture life becomes infinite and the cost is reduced.

In the above description, the impurity diffusion process is described. However, the method of manufacturing a semiconductor device according to the present invention is applicable to all the processes before the heat treatment except the diffusion process from a solid phase such as BPSG CVD or GPSG. Process, for example, thermal oxidation pretreatment, CVD (Poly CV
D, Si ₃ N ₄ CVD, TEOS) pretreatment, epitaxial pretreatment, annealing pretreatment, and the like.

Further, as the final processing of the resist peeling and cleaning processing of FIG. 1D, the surface treatment apparatus 100 of the present invention is used.
Can be installed in conjunction with each other to perform continuous processing.

[0040]

As described above, according to the present invention,
B can be prevented from entering the Si wafer by an extremely simple method, and the electrical characteristics of the semiconductor device can be stabilized. In addition, a number of excellent effects can be obtained, for example, a surface treatment apparatus for performing this can be configured very simply and inexpensively.

[Brief description of the drawings]

FIG. 1 is a manufacturing flow of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a hot water treatment tank suitable for use in the method of manufacturing a semiconductor device according to the present invention.

FIG. 3 is a graph showing the effect of removing boron by hot water treatment.

FIG. 4 is a schematic sectional view of a surface treatment apparatus according to an embodiment of the present invention.

FIG. 5 is a graph showing the amount of boron adhering to a Si wafer before hot water treatment and after hot water treatment when left in a product storage box for a long time.

FIG. 6 is a manufacturing flow for forming a typical impurity diffusion layer of a conventional semiconductor device.

FIG. 7 is a schematic view showing a behavior of a boron compound in a heat treatment.

8A and 8B show impurity profiles, FIG. 8A shows a normal profile, and FIG. 8B shows a profile when B is mixed.

[Explanation of symbols]

1 ... Si wafer, 2 ... SiO ₂ layer, 3 ... resist, 4 ...
Opening, 5 N-type impurity layer, 10 Loader, 20 Hot water treatment tank, 30 drying tank, 40 Unloader, 50 Work area, 60 Transferr, 100 Semiconductor wafer of one embodiment of the present invention Surface treatment apparatus 101, heat treatment reaction tube 1,
02 ... heater

Claims (2)

[Claims] 1. A method for manufacturing a semiconductor device, comprising: before heat treatment of a semiconductor substrate containing no boron, a surface treatment of an exposed surface of the semiconductor substrate with warm water isolated from boron. 2. A loader, a hot water treatment tank, a drying tank, and an unloader are sequentially disposed below, and a transfer device disposed so as to be able to traverse above them, and a chemical so as to cover them further. An apparatus for treating a surface of a semiconductor substrate, comprising a filter disposed therein.