JPS61199638A - Method for formation of insulating film - Google Patents

Abstract

PURPOSE:To enable to form a uniform insulating film on the surface layer part of a substrate at a high speed by a method wherein an energy beam to be absorbed into the substrate is made to irradiate on the substrate in a strong reactive gas atmosphere, an insulating layer composed of the constituting atoms of strong reactive gas and the constituting atoms of the substrate is formed on the surface of said substrate. CONSTITUTION:A silicon substrate 2 is placed in a reaction chamber 4 located in an insulating film forming device 1 as a substrate, O3/O2 gas is fed from a gas feeding hole 7, and the atmosphere of said reaction chamber 4 is formed into the state of O3/O2. The surface layer part only of the silicon substrate 2 is heated up by projecting the laser beam (a) of an XeCl excimer laser 3 which is made to irradiate through the intermediary of the quartz window 5 and the lens provided above the insulating film forming device 1. The reaction of the silicon atoms of the oxygen atoms of the O3/O2 gas and the silicon substrate 2 is generated on the surface part of the silicon substrate 2, and a silicon oxide film is formed on the surface layer of the silicon substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming an insulating film, and particularly to a method for forming an insulating film on the surface of a semiconductor.

[Conventional technology]

In recent years, in the manufacturing process of semiconductor devices, insulating film formation, typified by oxide film formation, has become an indispensable technique.

Conventionally, methods for forming insulating films on semiconductor substrates such as silicon substrates in the manufacturing process of semiconductor devices include thermal oxidation methods such as dry oxidation and steam oxidation, and vapor phase growth methods. There is.

However, the demand for yield improvement due to technological advances,
There is a demand for not only two-dimensional but also three-dimensional miniaturization, and a method to form an oxide film quickly and with high precision at low temperatures is required as a technology to meet these demands. A short-wavelength laser that is absorbed by the surface layer of the semiconductor substrate and instantaneously heats the surface layer is irradiated onto the semiconductor substrate in an oxygen atmosphere while keeping the inside of the semiconductor substrate at a low temperature to quickly form an oxide film on the surface layer. At the same time, a method for forming an oxide film that prevents the occurrence of internal distortion is known.

[Problem that the invention seeks to solve]

As mentioned above, a short wavelength laser has the advantage of not only being able to form an oxide film at high speed but also being able to perform oxidation at low temperatures without damaging the inside of the substrate. but,
If the atmosphere is oxygen 02, the oxidation reaction rate on the surface is slow, and the performance of the short wavelength laser cannot be brought out sufficiently.The oxidation reaction takes place instantaneously and at a low temperature, so that SiO and 5i02 coexist. There was a risk that a non-uniform oxide film would be formed.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a method for uniformly forming an insulating film on the surface layer of a substrate at high speed.

(Means for Solving the Problems) The present invention irradiates the substrate with an energy beam that is absorbed by the substrate in a strongly reactive gas atmosphere, and the constituent atoms of the strongly reactive gas and the constituent atoms of the substrate are exposed to the surface of the substrate. The above-mentioned problems are solved by a method of forming an insulating layer composed of the following.

[Effect]

By using a strongly reactive gas to increase the rate of insulating film formation and an energy beam capable of forming an insulating film at high speed, an insulating film can be uniformly formed on the surface layer of a substrate in a short time.

〔Example〕 Preferred embodiments of the present invention will be described with reference to the drawings.

As a first example, a laser beam a of a XeCt excimer laser (wavelength: 308 nm) is used as the energy beam, and an atmosphere containing ozone (02 gas, 0.5 atm and 1% 03 gas) is used as the strongly reactive gas atmosphere. An example in which an oxide film is formed on a silicon substrate in a mixed gas of 02 gas containing 0.5 atmospheres (hereinafter, this mixed gas will be referred to as 031011 gas) will be described.

As shown in FIG. 1, a silicon substrate 2 is placed as a substrate in a reaction chamber 4 inside an insulating film forming apparatus l, and air is supplied from the lower air supply.
S102 gas is sent to change the atmosphere of this reaction chamber 4 to 0370.
Set it to 2. A laser beam a of a XeC1 excimer laser 3 is irradiated onto the silicon substrate 2 through a quartz window 5 and a lens 6 provided on the upper part of the insulating film forming apparatus 1. Only the surface layer portion is heated, and a reaction is caused between the oxygen atoms of the 0s102 gas and the silicon atoms of the silicon substrate 2 in this portion, thereby forming a silicon oxide film on the surface layer of the silicon substrate 2.

The laser beam a of the XeCl excimer laser 3 was used under irradiation conditions with a laser energy of 500 mJ/aj, a pulse width of 35n3, and a total of 800 pulses at 10 pulses per second.

The reaction that occurs in the surface layer of the silicon substrate 2 is thought to proceed in two steps: a) 03 + Si → s to + o 2 and b) SiO + 0 3 → 5 to 2 + o 2 .
This is an oxidation reaction in the surface layer of

The state of formation of this oxide film was investigated by spectroscopic analysis of infrared absorption spectra, and the results are shown in FIG.

As shown in Figure 2, the absorption spectrum of the silicon oxide film formed by the 0s10s gas (indicated by the solid line in Figure 2) has a peak corresponding to the stretching mode absorption of silicon oxide in the wave number region of 1100 cm→. has
At this peak, absorption occurs more strongly than in the absorption spectrum of the silicon oxide film formed by the 02 gas (indicated by the broken line in Figure 2), indicating that a thicker silicon oxide film is formed. It can be seen that the oxidation rate increases. Further, this peak shows a sharp rise without fluctuation even when compared with the absorption spectrum of a silicon oxide film formed using 02 gas, indicating that a uniform silicon oxide film is formed.

In the first embodiment described above, an example was shown in which the silicon substrate 2 was used as a substrate, but as described above, the present invention is capable of absorbing a strongly reactive gas by absorbing an energy beam on the substrate. Since the energy beam causes a thermal reaction, the wavelength of the energy beam is limited for each substrate.

For example, when the constituent atoms are silicon atoms like the silicon substrate 2, the wavelength λ of the energy beam necessary for heating is required to be λ<1130 nm, and furthermore, In order to perform oxidation without causing internal thermal strain, it is preferable that the absorption coefficient α, which is at least the attenuation constant related to energy absorption, satisfies α>lQ3cm'. In the case of silicon, the wavelength λ that satisfies this condition is λ<650 nm.For example, in the case of a laser as the energy beam that is the light source, Ar laser, XeCl excimer laser - 1XeF excimer laser - 2KrF excimer laser -1A r F excimer laser - 1 Furthermore, second or higher harmonics such as a ruby laser or a YAG laser can be used. Furthermore, a light source such as a low-pressure mercury lamp, an electron beam, or an ion beam may be used, or an energy beam obtained by a combination of the above light sources may be used.

In addition, when using a pulsed laser of the short wavelength laser mentioned above, the pulse width
There are conditions for sufficient oxidation depending on the setting of the surface temperature and the characteristics of the above-mentioned strongly reactive gas, and the pulse width τ is preferably 2JD・τ<10(aa) (D: thermal diffusion coefficient). Therefore, in the case of a silicon substrate, it is desirable that τqy><130 (ps).

The strongly reactive gas used in the insulating film forming method of the present invention is
In the first embodiment described above, 02 gas, 0°5 atm and 1%
Although the oxide film was formed using O2 gas containing 03 gas and a mixed gas of 0.5 atm, the oxide film is not limited to this and may be formed using other gases. For example, WS It is also possible to use No gas, N, O gas, and No2 gas as the oxide. In addition, halogen F2, C1
An insulating film such as an oxide film may be formed using a gas such as 2, Br2, or 2, or a halogen compound gas such as CC14 or SF6. Furthermore, ammonia gas may be used to form a nitride film.

The pressure of the strongly reactive gas is not limited to the partial pressure of the 03 gas in the first embodiment; for example, the pressure may be controlled from normal pressure to high pressure by increasing the partial pressure of the 03 gas. By doing so, the reaction rate can be further improved.

In addition, as an application of the method of irradiating the substrate with an energy beam in this strongly reactive gas atmosphere to heat the substrate and cause a reaction to form an insulating film, for example, GaAs, which has high electron mobility, It can also be applied to substrates such as substrates, and although there was conventional concern that harmful arsenic would be generated during oxidation, it is possible to suppress the generation of arsenic inside the substrate and form an oxide film on the surface. . Furthermore, any substrate may be used as long as it can form an insulating film made of a material such as Ta% Mos A1.

Next, as a second embodiment of the present invention, an energy beam is irradiated onto the substrate in a strongly reactive gas atmosphere to melt the surface layer of the substrate, thereby increasing the temperature of the substrate without affecting the internal characteristics of the substrate. An example in which an insulating film is formed quickly will be explained.

In the second example, the insulating film forming apparatus l described in the first example was used, and a silicon substrate 2 in an 0s102 gas atmosphere was similarly irradiated with the laser beam a of the XeCl excimer laser 3. .

The energy required to melt the surface layer of the silicon substrate 2 is approximately 260 mJ/-, and considering the reflection of the laser beam a of the XeCl excimer laser 3 on the surface of the silicon substrate 2, the energy required is approximately 650 mJ/aJ. For example, in the case of an energy beam of 1100 mJ/-, the melting region extends from the surface layer to a depth of about 340 nm, and as the melting region expands, the oxidation rate also increases.

Due to this melting of the surface layer, in the case of this example, 031
0! Oxygen, which is an atom contained in the I gas, chemically bonds with silicon, which is a constituent atom of the substrate, to produce silicon oxide. In this case, the melting of the substrate surface increases the chances of bonding between silicon atoms and oxygen atoms, so it is thought that a silicon oxide film can be formed in a shorter time compared to forming a silicon oxide film by simply heating. .

Note that the insulating film may be formed by irradiating an energy beam with a wavelength that enables the photolysis of the strongly reactive gas, and combining the photolysis with the heating and melting using the energy beam described above.

〔Effect of the invention〕

According to the method for forming an insulating film according to the present invention, the energy beam is absorbed only in the surface layer of the substrate, and the strongly reactive gas reacts in this surface layer in a short time to form an insulating film. A uniform insulating film can be formed at high speed without damaging the film. Furthermore, the method using melting allows the insulating film to be formed more quickly.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a manufacturing apparatus embodying the manufacturing method of the present invention, and FIG. 2 shows an atmosphere of 03102 gas and 0
FIG. 3 is a characteristic diagram comparing measurement data of absorption spectra of insulating films when two gases are used. l... Insulating film forming device 2... Substrate (silicon wafer) 3... XeCl excimer laser a... Laser beam (energy beam) patent
Applicant Sony Corporation Representative Patent Attorney
Koike wide open Tamura Sakae - s1! 1 % 2 g Procedure Neho (self-initiated) ■, Indication of the case 1985 Patent Application No. 40175 2, Name of the invention Method of forming an insulating film 3° Relationship with the amendment person case Patent applicant address Tokyo 6-7-35, Kita-Shinyo, Parts Ward Name (2
18) Sony Co., Ltd. Company Representative: Norio Oga 4, Agent Address: 11, 2-6-4 Toranomon, Minato-ku, Tokyo 105
Mori Building 11th floor (50B) 8266 F5
No. 6, Column I-1 of "Detailed Description of the Invention" of the specification to be amended; " is corrected to "excimer laser light." (2) "Short wavelength laser" written on page 2, line 9 of the specification is corrected to "short wavelength laser light." (3) Specification , written in the 3rd line of page 8 "(p3)
" is corrected to [(μm)J. (4) “130” written on page 8, line 7 of the specification
Correct it to rl, 3J. (5) rGaAs described in the specification, page 9, line 9
Insert [ or InPJ after J. (6) "Harmful arsenic" stated on page 9, line 11 of the specification will be amended to "harmful arsenic and phosphorus." (7) "Arsenic inside the substrate" stated on page 9, line 12 of the specification is corrected to "arsenic and phosphorus inside the substrate because it oxidizes in a short time." . that's all

Claims (1)

[Claims] In an atmosphere containing a strongly reactive gas, the base is irradiated with an energy beam that is absorbed by the base to form an insulating film on the surface of the base consisting of atoms contained in the strongly reactive gas and constituent atoms of the base. How to form.