JP2001274155A - Method of forming insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart flat and good embedding characteristics to an oxide film formed through a vacuum ultraviolet light CVD process. SOLUTION: At the formation of the oxide film on a substrate by a vacuum ultraviolet light CVD process, an organic material gas and an additive gas of dinitrogen monoxide and/or oxygen gas (gases) are present together therewith. TEOS or the like is used as the organic material gas. By suitably increasing or decreasing the amount of active oxygen or ozone generated in a vapor phase, step coverage can be controlled. Thus, an SiO2 film can be obtained which has desired planarity and embedding characteristics. The method can be applied suitably to the formation of an interlayer insulating film or protective film in a semiconductor element, such as ULSI which demands high integration density and multilayer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for forming an insulating film on an object using excimer light.

[0002]

2. Description of the Related Art Interlayer insulating films for DRAMs and LOGICs are plasma oxide films, thermal oxide films, ozone (O ₃ ) -tetraethyl orthosilicate (Si (C ₂ H ₅ O) ₄ ).
(Hereinafter, referred to as “TEOS”). However, when forming these oxide films, thermal oxidation is performed at 700 ° C. or more, and plasma oxidation and ozone-
High temperature heat treatment of 350 ° C. or more is required even in TEOS oxidation.
In addition, plasma discharge occurs in plasma oxidation. These high-temperature heat treatments or plasma discharges cause damage to an object on which an insulating film is formed. In particular, in the case of a semiconductor device, it is inevitable that further miniaturization and multilayer wiring will progress in the future, and the damage due to heat or plasma cannot be ignored in maintaining the quality of the semiconductor device.

In recent years, as a means for solving the above problem, an organic material gas, for example, TEOS is irradiated with excimer light from a xenon excimer lamp, an argon excimer lamp or the like, decomposed at room temperature, and an oxide film is formed on the semiconductor element. UV light CVD method for forming GaN has been proposed (Wataru Sasaki et al., "Silica Thin Film Formation Using Vacuum Ultraviolet Excimer Lamp", 46th Annual Meeting of the Japan Society of Applied Physics, 28a-M-5)
(1999, Spring)) (U. Kogelschatz)
"Appln. Surf. Sci. 54 , 146
3 (1992)). According to the vacuum ultraviolet light CVD method, the photon energy of excimer light is 7.2 eV or more, whereas the binding energy of most organic material gases, for example, CH, CC of TEOS, is 6 eV. Therefore, an oxide film (SiO ₂ ) which is easily decomposed even at a low temperature such as a normal temperature and has no heat or plasma damage can be formed on a semiconductor element.

[0004]

SUMMARY OF THE INVENTION However, TEO
Vacuum ultraviolet light C using only organic material gas such as S
By VD, for example, Si is used as an interlayer insulating film of a semiconductor element.
When the O ₂ film is formed, as shown in FIG. 2, the O ₂ film is formed in an overhang shape. This is probably because TEOS alone decomposes in the gas phase due to light energy and deposits on the wafer as if snow falls. Overhang-shaped film formation has poor step coverage (step coverage), and when the wiring interval is 0.5 μm or less, voids are generated and reliability is reduced.

An object of the present invention is to provide a method for forming an insulating film having a flat characteristic with few voids.

[0006]

According to a method of forming an insulating film of the present invention, which achieves the above object, an organic material gas and an oxygen-containing gas are formed when an insulating film derived from an organic material gas is formed on an object to be processed by excimer light. The method is characterized by irradiating excimer light in the coexistence of a gas containing, and forming an oxide film having few voids and flat characteristics.

The organic material gas in the present invention includes:
In addition to TEOS, tetramethoxy orthosilicate (TM
OS), tetramethyl silicate (TMS) and the like.

The gas containing oxygen in the present invention is not particularly limited, but is preferably an oxygen gas (O ₂ ) and a nitrous oxide gas (N ₂ O) alone or a mixture thereof.

The application of the present invention is most suitable for an interlayer insulating film of a semiconductor element, but can be widely applied to, for example, plastics and metals which are not suitable for high-temperature treatment.

In the present invention, the reason why an insulating film having few voids and excellent in flatness characteristics is formed is not necessarily clear, but oxygen gas is decomposed by excimer light to become active oxygen, and this active oxygen is made of an organic material. It is considered to react with the gas to give fluidity.

[0011]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows an example of an apparatus used for the method of forming an insulating film according to the present invention. In FIG.
The processing chamber 1 for forming a semiconductor element oxide film has an airtight structure that can be evacuated, and is connected to a vacuum pump 3 for exhaust through a pipe 2. The processing chamber 1 is provided with gas supply pipes 4 and 4a, and supplies an organic material gas from the gas supply pipe 4 and an additional gas containing oxygen from the gas supply pipe 4a. An excimer lamp 5 is provided above the processing chamber 1. The excimer lamp 5 is filled with an excimer light generating rare gas. Examples of the rare gas include argon (126 nm), krypton (146 nm), and xenon (172 nm) alone or a mixed gas thereof, such as an argon / krypton mixed gas (135 nm) and a krypton / xenon mixed gas (165 nm). Is appropriately selected according to the photon energy of the above and the binding energy of the organic material gas used. Reference numeral 6 denotes an excimer light extraction window of the lamp 5. Quartz, magnesium fluoride, calcium fluoride, barium fluoride, sapphire, or the like can be used for the window member. Since each of these window members has the shortest wavelength of excimer light that can be transmitted,
It may be appropriately selected depending on the relationship with the rare gas used, but magnesium fluoride, synthetic quartz, or the like, which does not absorb short-wavelength light, is preferable. A susceptor 8 supported by a support rod 7 is provided in the processing chamber 1. An object to be processed, for example, a semiconductor element wafer 9 is placed on the susceptor 8. Reference numeral 10 denotes an oxide film formed on the wafer 9.

According to the present invention, an insulating film is formed as follows using the above-described insulating film forming apparatus. First, the semiconductor element wafer 9 is placed on the susceptor 8 in the processing chamber 1 of the apparatus shown in FIG. The processing chamber 1 is evacuated to about 1E-5 Torr by the vacuum pump 3 through the pipe 2,
Reduce residual gas. Next, the liquid TEOS is vaporized by the vaporizer from the gas supply pipe 4 to about 1 to 100.
About 0 ml is introduced into the processing chamber 1. At the same time, about 1 to 1000 ml of a single gas or a mixed gas such as an oxygen gas and a nitrous oxide gas is added as an additional gas. The internal pressure of the processing chamber 1 is several m to 1000 mTorr, preferably 1E-1 to 1E-1.
Maintain at 100 Torr. In this state, for example, a xenon excimer lamp 5 is irradiated to decompose the TEOS gas and deposit an oxide film 10 on the wafer 9 on the susceptor 8. The distance between the excimer lamp 5 and the susceptor 8 is 1 to 20
It is about 0 mm. TEOS flow rate, additive gas flow rate, irradiation time, processing chamber pressure, distance between lamp and susceptor, etc.
It is appropriately selected according to the desired film quality, film thickness and the like.

In the present invention, by appropriately increasing or decreasing the amount of oxygen radicals (active oxygen) or ozone generated in the gas phase, the step coverage can be controlled, and a high-quality oxide film with few voids can be obtained.

[0014]

[Embodiment 1] A susceptor in a processing chamber 1 was manufactured using the apparatus shown in FIG.
Wiring pattern used for semiconductor device on
Was placed on the silicon wafer 9. Wiring pattern
Wiring width 300nm, wiring interval 300nm, step 500n
m. Organic materials to be introduced into the processing chamber 1 include
TEOS was used. TEOS partial pressure is 300mTorr
r, the flow rate was 500 ml / min. As additional gas
N₂O was used. The partial pressure and flow rate of the mixed gas are TEOS
It was the same as that of The excimer light extraction window 6 has a thickness of 2
0 mm synthetic quartz was used. Excimer light extraction window 6 and wafer
The distance of c was 15 mm. Illumination of excimer lamp 5
The degree is 12 mW / cm just below the extraction window 6² Met. Release
The irradiance was measured using an illuminometer (UI
T-150) was used. The irradiation time of vacuum ultraviolet light depends on the film
The thickness was adjusted to 3000 mm.

[0015]

Example 2 The conditions were the same as in Example 3, except that O ₂ was used instead of N ₂ O as the additional gas.

[0016]

Comparative Example 1 The conditions were the same as in Example 1 except that the test was performed using only TEOS without using any additional gas.

[0017]

Test Example 1 According to Examples 1 and 2 and Comparative Example 2, SiO
_Two The state in which the film is formed is shown by a cross-sectional SEM photograph. Comparative Example 1
(TEOS only), as shown in FIG.
H₄System CVD SiO₂Overhang shape like membrane
And voids are observed between wiring patterns.
You. On the other hand, in Example 1 (N₂In case of O),
As shown in 2 (b), the film is formed conformally.
You. Also, in Example 2 (O₂ In the case of), FIG.
As shown, O₃ ・ CVD SiO of TEOS₂Like a membrane
The film becomes self-flat and the voids are buried.
Is not allowed.

[0018]

According to the method for forming a semiconductor device insulating film of the present invention, an oxide film (SiO 2) having good flatness and burying characteristics can be obtained.
₂ ) is obtained. If the surface of the oxide film has irregularities, light is scattered at the time of pattern formation, causing a problem that the pattern is narrowed. Therefore, it is suitable for an interlayer insulating film or a protective film of a semiconductor element such as ULSI which requires high density and multilayer. Further, it can be widely used for a gate insulating film, a low dielectric constant insulating film, and the like used for a semiconductor element. In addition to semiconductor devices,
It can also be applied to high-quality insulating film coating on plastics and the like that cannot be processed at high temperatures, and high-quality insulating film coating as a metal protective film.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an oxide film forming apparatus used in the present invention.

FIG. 2 is an SME photograph showing a cross section of an oxide film according to Examples 1 and 2 and Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Processing chamber 2 ... Hyp 3 ... Vacuum pump 4, 4a ... Gas supply pipe 5 ... Excimer lamp 6 ... Extraction window 7 ... Support rod 8 ... Susceptor 9 ... Wafer 10 ... Oxide film

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 390008855 Miyazaki Oki Electric Co., Ltd. 727 Kihara, Oaza, Kiyotake-cho, Miyazaki-gun, Miyazaki (71) Applicant 592075884 Kiyomoto Tekko Co., Ltd. (71) Applicant 598049746 Miyazaki Daishin Cannon Co., Ltd. 4308-1 Takajo, Kijocho, Koyu-gun, Miyazaki Prefecture (71) Applicant 000000295 Oki Electric Industry Co., Ltd. 1-7-12 Toranomon, Minato-ku, Tokyo (72) Inventor Kurosawa Hiroshi 38, Saigo, Nishigo, Myoudaiji, Okazaki City, Aichi Prefecture Okazaki National Collaborative Research Organization Molecular Science Research Institute (72) Inventor Atsushi Yokoya 1-1-1, Gakuen Kihanadai Nishi, Miyazaki City, Miyazaki Prefecture Miyazaki University Faculty of Engineering, Miyazaki University Indoor (72) Inventor Junichi Miyano 727 Kihara, Oaza, Kiyotake-cho, Miyazaki-gun, Miyazaki Prefecture Inside Miyazaki Oki Electric Co., Ltd. (72) Inventor Motoyama Riichi 727 Kihara, Kiyotake-cho, Miyazaki-gun, Miyazaki Prefecture Miyazaki Oki Electric Co., Ltd. (72) Inventor Kiyohiko Toshikawa 727 Kihara, Kiyotake-cho, Miyazaki-gun, Miyazaki Miyazaki Oki Electric Co., Ltd. F-term (reference) 4K030 AA11 AA14 CA04 CA12 FA08 5F033 HH19 RR04 SS02 SS03 SS04 SS14 XX01 XX02 5F058 BA09 BC02 BF05 BF07 BF25 BF29 BF37 BJ01 BJ02

Claims (3)

[Claims] When an insulating film derived from an organic material gas is formed on an object to be processed by excimer light, the film is irradiated with excimer light in the coexistence of an organic material gas and a gas containing oxygen. A method for forming an insulating film, comprising forming an oxide film having characteristics. 2. The insulation according to claim 1, wherein the gas containing oxygen is at least one selected from the group consisting of oxygen gas (O ₂ ) and nitrous oxide gas (N ₂ O). Method of forming a film. 3. The method according to claim 1, wherein the object to be processed is a silicon wafer carrying semiconductor elements.