JP2003078119A - Method of manufacturing simox wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a low-dosed SIMOX wafer which is provided with a buried oxide film of high reliability and superior in productivity. SOLUTION: Oxygen ions of 4×10<17> atoms/cm<2> or below in doses are implanted into a silicon wafer, then the silicon wafer is thermally treated at a temperature of 1000 deg.C or above at a temperature rise rate of 100 deg.C/min or above and then thermally treated again at a temperature of 1200 deg.C or above in an atmosphere whose oxygen concentration is 1% or above.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to SIMOX (Se).
partition by ImplantedOxyg
en) The present invention relates to a method for manufacturing a wafer, and more particularly to a method for manufacturing a low dose SIMOX wafer having a highly reliable buried oxide film and high productivity.

[0002]

2. Description of the Related Art SOI (Silicon on Ins)
SIMOX is one of the wafer manufacturing methods.
Method (K. Izumi et al .: Electro
n. Lett. 14 (1978) 593).

The concept at the beginning of the development of the SIMOX technology is that the acceleration energy is about 200 keV, and about 2 × 10 ¹⁸ ato.
After implanting oxygen atoms of ms / cm ² to form a stoichiometric buried oxide film (hereinafter, the buried oxide film is referred to as “BOX (Buried Oxide)”) by as-implantation, an SOI layer is formed. Heat treatment is performed to recover the crystallinity and modify the BOX layer. The SIMOX wafer produced by this manufacturing method is called a high-dose SIMOX wafer.

However, this high-dose SIMOX wafer has problems such as a large number of threading dislocations in the SOI layer and a long oxygen ion implantation time and high manufacturing cost.

Therefore, the threading dislocation in the SOI layer is reduced and the cost is reduced.
Many studies have been conducted on reduction, and low dose SIMOX
Technology (S. Nakashima et al .: JM
ater. Res. 8 (1993) 523) was developed
It was With this low dose SIMOX technology, the acceleration energy
4 × 10 for 180 keV¹⁷atoms / cm ^Two
After implanting oxygen atoms of
To form a continuous BOX layer. Formation of continuous BOX layer
Has a dose of 4 when the acceleration energy is 180 keV.
× 10¹⁷atoms / cm^TwoPossible only in the case of
Therefore, this dose amount is called the dose window.
Be done.

However, in the low-dose SIMOX wafer, the reliability of the BOX becomes a problem because the thickness of the BOX layer is thin, and the ITOX (Internal) was developed there.
Thermal Oxidation, S.M. Naka
Shima et al. : Proc. 1994 IE
EE International SOI Conf
erence (1994) 71; JP-A-7-26353.
No. 8 publication) technology.

The ITOX technique is a heat treatment in an atmosphere containing less than 1% oxygen, which is a theoretical film thickness calculated by the dose of oxygen ions, and then a heat treatment in an atmosphere containing more than 1% oxygen. This is a technique for increasing the thickness of the BOX layer.

Low dose SIM due to introduction of ITOX technology
Low dose SIMOX wafers having improved BOX reliability of OX wafers and subjected to ITOX treatment are currently on the market. However, pinholes still remain in the BOX layer after the ITOX treatment, and it cannot be said that sufficient BOX reliability is obtained.

The reason why pinholes remain in the BOX layer even after the ITOX treatment is described below. In the conventional low-dose SIMOX wafer manufacturing process, the crystallinity of the SOI layer and the formation of the BOX layer are simultaneously performed by performing heat treatment in an atmosphere of low oxygen concentration. Therefore, when the BOX layer is formed by the heat treatment, oxygen in the heat treatment atmosphere cannot be used, and thus pinholes are formed in the portions where the dose amount is insufficient due to particles or the like attached to the wafer surface during the ion implantation. Although smaller pinholes can be eliminated by the subsequent ITOX treatment, large pinholes cannot be eliminated and remain after the ITOX treatment.

A method of performing heat treatment in an atmosphere of high oxygen concentration in the manufacturing process of a low dose SIMOX wafer has also been proposed (A. Ogura: Appl. Phy.
s. Lett. 74 (1999) 2188;
0-150408). The one method will be specifically described with reference to FIG.

First, on a silicon wafer 1, an acceleration energy of 180 keV and a dose of 4 × 10 ¹⁷ atoms /
A cm ² oxygen atom ion is implanted to form a high concentration layer 2 of oxygen. After that, heat treatment is performed at 1340 ° C. for 5 hours in an Ar atmosphere containing 20% oxygen. However, in this method, oxygen that diffuses inward from the wafer surface is deposited on the damaged layer 4 in the SOI layer 3 and the BOX layer 5 is formed at a position different from the ion-implanted high-concentration layer 2 of oxygen.
There is a problem that a long heat treatment is required to form the OX layer 5.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a low dose SIMOX wafer having high BOX reliability and high productivity. There is.

[0013]

The invention described in the first claim of the present application is a method for manufacturing a SIMOX wafer, which comprises a step of implanting oxygen ions into a silicon wafer, and a step of subjecting the silicon wafer to heat treatment. After that, heat treatment is performed at a temperature rising rate of 100 ° C./min or more at 1000 ° C. or more, and then 1200 ° C. in an atmosphere having an oxygen concentration of 1% or more.
It is a method for manufacturing a SIMOX wafer, which is characterized by performing a heat treatment at a temperature of not less than ° C.

This is because the temperature rising rate is 10 after the ion implantation.
By performing heat treatment at 1000 ° C. or higher at a high temperature rising rate of 0 ° C./min or higher, damage due to ion implantation is removed and the distribution of ion-implanted oxygen is maintained. Then, in an atmosphere of high oxygen concentration of 1% or more,
It is intended that both the ion-implanted oxygen and the oxygen in the heat treatment atmosphere are used for forming the BOX layer by performing the heat treatment at 200 ° C. or higher.

To completely recover the crystallinity of the SOI layer, 1
A temperature of 000 ° C. or higher is required, but when the heating rate up to 1000 ° C. is lower than 100 ° C./min, dislocations grow, so the heating rate and maximum temperature in the heat treatment for recovering the crystallinity of the SOI layer Lower limit of 100 ℃ / m
in and 1000 ° C. Further, when the oxygen concentration in the heat treatment atmosphere is less than 1%, oxygen in the heat treatment atmosphere cannot be used for forming the BOX layer, and when the maximum temperature is less than 1200 ° C.
Since the layer quality is inferior to that of the thermal oxide film, the lower limits of the oxygen concentration and the maximum temperature in the heat treatment for forming the BOX layer were set to 1% and 1200 ° C., respectively.

According to the second aspect of the present invention, the dose amount of oxygen ions implanted into the silicon wafer is 4 × 10.
¹⁷ atoms / cm ² or less,
A method for manufacturing a SIMOX wafer according to claim 1 of the present application.

In the present invention, since both the ion-implanted oxygen and the oxygen in the heat treatment atmosphere can be used for forming the BOX layer, the dose of oxygen ions is 4 × 10 ¹⁷ atoms / s.
Since it is effective in the production of a low dose SIMOX wafer of cm ² or less, the upper limit of the dose amount of oxygen ions is set to 4
It was set to × 10 ¹⁷ atoms / cm ² .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings.

1 (a), 1 (b) and 1 (c) are explanatory views showing a flow of a SIMOX wafer manufacturing process according to the present invention by a schematic partial cross section of a wafer. First, oxygen atom ions having a dose amount of 4 × 10 ¹⁷ atoms / cm ² were implanted into a silicon wafer 1 at an acceleration energy of 180 keV to form a high concentration layer 2 of oxygen. At this time, SOI
A damage layer 4 is formed in the layer 3. Next, heat treatment was performed using a lamp annealing device (not shown). As the heat treatment condition, the temperature raising / lowering rate is 2000 ° C./min,
The maximum temperature of 1150 ° C. was maintained for 10 seconds. The heat treatment atmosphere was Ar. Then, heat treatment was performed at 1350 ° C. for 4 hours in an Ar atmosphere containing 20% oxygen.
The result is shown in FIG. 1C. Since the heat treatment was performed in an atmosphere of high oxygen concentration after removing the damage due to the ion implantation, the oxygen diffused inward from the wafer surface was SOI.
It is not deposited on the damaged layer 4 in the layer 3 but is deposited on the ion-implanted oxygen high concentration layer 2 to form a highly reliable BOX layer 5.

After that, the oxide film 6 on the wafer surface and the SOI
Layer 3 and HF solution and TMAH (Tetramet, respectively)
Hyalmmonium Hydroxide) solution was used, and then an Al electrode was formed on the exposed surface of the BOX layer 5 to evaluate the withstand voltage of the BOX layer 5. As a result, the BOX layers of the SIMOX wafer of the present invention were all in the C mode, and there were no A mode defects.

As a comparative example, 0.5% oxygen is added to a silicon wafer ion-implanted in the same batch as the embodiment.
As a result of performing a heat treatment at 1350 ° C. for 4 hours in the contained Ar atmosphere and evaluating the withstand voltage of the BOX layer by the same method as that of the embodiment, all were A mode defects or B mode defects.

As a comparative example, a silicon wafer ion-implanted in the same batch as that of the embodiment is heat-treated at 1350 ° C. for 4 hours in an Ar atmosphere containing 0.5% oxygen, and then oxygen is added. 1 in Ar atmosphere containing 70%
As a result of performing the ITOX treatment at 350 ° C. for 4 hours and evaluating the withstand voltage of the BOX layer by the same method as the embodiment,
C mode was 90% or more, but A mode defects were also a few%
there were.

Next, a second embodiment of the present invention will be described.

Acceleration energy 18 is applied to a silicon wafer.
After implanting oxygen atom ions with a dose amount of 3 × 10 ¹⁷ atoms / cm ² at 0 keV, the same heat treatment as in the first embodiment was performed, and the dielectric breakdown voltage of the BOX layer 5 was evaluated in the same manner. There was no A mode defect.

That is, in the present invention, since both the ion-implanted oxygen and the oxygen in the heat treatment atmosphere can be used for forming the BOX layer, the BOX layer is interrupted even if the dose amount is reduced as compared with the conventional low dose SIMOX method. It turns out that it can be formed without any.

[0026]

According to the present invention, after the damage due to the ion implantation is removed, heat treatment is performed in an atmosphere of high oxygen concentration, so that both the ion-implanted oxygen and the oxygen in the heat treatment atmosphere form a BOX layer. Since it is available, BOX
It is possible to manufacture a low dose SIMOX wafer with high reliability and high productivity.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a flow of manufacturing steps of a SIMOX wafer according to the present invention by a schematic partial cross section of the wafer.

FIG. 2 is an explanatory view showing a flow of manufacturing steps of a conventional low-dose SIMOX wafer in which BOX is formed on a damaged layer, by a schematic partial cross section of the wafer.

[Explanation of symbols]

1 Silicon wafer 2 High concentration layer of oxygen 3 SOI layer 4 Damage layer 5 BOX layer 6 Oxide film on wafer surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhiro Yamamoto             2201 Kamioda, Oita, Kohoku-cho, Kishima-gun, Saga Prefecture             Sumitomo Metal Industries, Ltd. Sitix Business Division             Within (72) Inventor Yasuo Koike             2201 Kamioda, Oita, Kohoku-cho, Kishima-gun, Saga Prefecture             Sumitomo Metal Industries, Ltd. Sitix Business Division             Within F-term (reference) 5F032 AA91 CA01 DA43 DA60 DA74

Claims (2)

[Claims] 1. A method of manufacturing a SIMOX wafer, which comprises a step of implanting oxygen ions into a silicon wafer and a step of subjecting it to heat treatment. After implanting oxygen ions, the temperature rising rate is 100 ° C./min or more and 1000 ° C. or more. Heat treatment, and then in an atmosphere with an oxygen concentration of 1% or more, 12
SIMOX, characterized by being subjected to heat treatment at 00 ° C or higher
Wafer manufacturing method. 2. The method for manufacturing a SIMOX wafer according to claim 1, wherein the dose amount of oxygen ions implanted into the silicon wafer is 4 × 10 ¹⁷ atoms / cm ² or less.