JP3463195B2 - Method of forming insulating film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an insulating film, and more particularly to a method for forming an insulating film on the surface of an object to be processed using excimer light in the presence of an organic oxide film forming gas.

[0002]

2. Description of the Related Art Conventionally, for example, an insulating film used for an interlayer insulating film of DRAM, LOGIC, etc. is a plasma oxide film, a thermal oxide film, ozone (O ₃ ) -tetraethyl orthosilicate (Si (C ₂ H ₅ O) ₄ ) (hereinafter "TEOS"
It is formed of an oxide film or the like. However,
When forming these oxide films, thermal oxidation is 700 ° C.
As described above, the plasma oxidation and the ozone-TEOS oxidation are 35
High temperature heat treatment of 0 ° C or higher is required. In addition, plasma oxidation causes plasma discharge. These high temperature heat treatments or plasma discharges damage the object to be processed forming the insulating film. Particularly in the case of semiconductor elements, further miniaturization and multilayer wiring are inevitable in the future, and damage due to heat or plasma cannot be ignored in terms of maintaining the quality of semiconductor elements.

In recent years, as a means for solving the above-mentioned problems, an organic oxide film forming gas such as TEOS is irradiated with excimer light from a xenon excimer lamp, an argon excimer lamp or the like, decomposed at room temperature, and decomposed on a semiconductor element. An optical CVD method for forming an oxide film has been proposed (Wataru Sasaki et al. "Silica thin film formation using a vacuum ultraviolet excimer lamp").
46th Japan Society of Applied Physics-Proceedings, 28a-M-5 (19
99, spring))). According to the photo CVD method, the photon energy of excimer light is 7.2 eV or more, while
Most organic oxide film forming gases, such as TEOS C-
Since the binding energy of H, C—C, etc. is 6 eV or less, it is easily decomposed even at a low temperature such as room temperature to form an oxide film (SiO ₂ ) on the semiconductor element.

[0004]

However, the oxide film formed by the above-described photo-CVD method contains a large amount of impurities such as carbon (C) derived from the organic oxide film forming gas, which may deteriorate the insulation property. is there. For this reason, the photo-CVD method is not available industrially as an insulating film for semiconductor devices, for example, although it has an advantage of low temperature treatment. On the other hand, in the photo-CVD method, an oxide film is deposited on the surface of the excimer light extraction window member from the lamp in the same manner as on the semiconductor element, and the illuminance of the excimer light is attenuated with time. There was a drawback that the formation of

The present invention solves the above problems, and provides a method for forming an insulating film, which stably forms a high-quality insulating film with less damage to the surface of the object to be processed and less impurities. It is an object.

[0006]

Means for Solving the Problems] The present invention has achieved the above object, the presence of an organic oxide film forming gas, in forming an insulating film on the object surface to be treated by the excimer light, excimer light
During the irradiation, an organic oxide film forming gas is intermittently supplied from the gas supply pipe (4), and a gas containing oxygen is added from the gas supply pipe (4a) when the organic oxide film forming gas is not supplied. Is characterized by.

In the present invention, this oxygen is converted into radical oxygen or ozone (O) by the photon energy of excimer light.
₃ ) and reacts with, for example, carbon (C) in TEOS to reduce organic impurities in the oxide film to be processed. In the vicinity of the excimer light extraction window member near the lamp, the illuminance of the excimer light is high, and radical oxygen or ozone (O ₃ ) is generated.
Is more likely to occur, it is possible to selectively suppress the deposition of the oxide film on the window member without damaging the formation of the oxide film on the surface of the object to be processed far from the lamp.

A semiconductor element is most suitable as the object to be processed of the present invention, but it can be widely applied to plastics and metals which are not suitable for high temperature processing.

The organic oxide film forming gas includes TEOS and
TMOS, TMS, etc. can be mentioned, but safety,
TEOS is practical for economic reasons (price).

The gas containing oxygen is not particularly limited, but oxygen gas (O ₂ ) and dinitrogen monoxide gas (N ₂ O), which are easy to handle, are preferably used alone or as a mixture.

In the method for forming an insulating film according to the second aspect of the present invention which achieves the above object, an organic oxide film forming gas is intermittently supplied when forming an insulating film on an object to be processed by excimer light. It is characterized by that.

When the supply means of the organic oxide film forming gas is digitally turned on / off and the organic oxide film forming gas is intermittently supplied, an oxide film is formed on the surface of the object to be processed at the time of supply and is not supplied. The photon energy of the excimer lamp sometimes breaks and removes carbon bonds on the surface of the insulating film and in the film.

In this case, when the gas containing oxygen is added when the organic oxide film forming gas is not supplied, the organic impurities are removed and the oxide film is deposited on the excimer light extraction window member for the same reason as in the first aspect of the invention. Prevention becomes even more effective.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows an example of an apparatus used in the insulating film forming method of the present invention. In FIG.
The processing chamber 1 for forming the semiconductor element oxide film has an airtight structure that can be evacuated, and is connected to a vacuum pump 3 for exhausting through a pipe 2. A gas supply pipe 4 is provided in the processing chamber 1, and an organic oxide film forming gas such as TEOS or a gas containing oxygen such as dinitrogen monoxide gas is supplied from the gas supply pipe 4. An excimer lamp 5 is provided above the processing chamber 1. The excimer lamp 5 is filled with a rare gas (not shown) that generates excimer light. Argon (126 nm) xenon (1
46 nm), krypton (172 nm) alone, or a mixed gas thereof, for example, an argon / krypton mixed gas (126 to 146 nm), a krypton / xenon mixed gas (146 to 172 nm), or the like, which is an organic system using these photon energies. It is appropriately selected according to the binding energy of the oxide film forming gas. Reference numeral 6 is 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 is appropriately selected in relation to the rare gas used.
For example, in the case of quartz, only light having a wavelength longer than that of xenon excimer light is transmitted. 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 this susceptor 8. Reference numeral 10 is an oxide film formed on the wafer 9, and 10a is an oxide film deposited on the surface of the excimer light extraction window.

In the present invention, an insulating film is formed as follows using the insulating film forming apparatus as described above. 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 to extremely reduce the residual gas. Then, liquid TEOS is vaporized from the gas supply pipe 4 by a vaporizer,
About 5 to 1000 ml is introduced into the processing chamber 1. At the same time, about 5 to 1000 ml of a gas containing oxygen such as oxygen gas or nitric oxide gas is added as an additive gas. The internal pressure of the processing chamber 1 is maintained at 1E-1 to 100 Torr.
In this state, for example, set the xenon-filled excimer lamp 5 to 1
Irradiation is performed for up to 1000 minutes to decompose the TEOS gas and deposit the oxide film 10 on the wafer 9 on the susceptor 8. In this case, the distance between the excimer lamp 5 and the susceptor 8 is 1 to 20.
It is about 0 mm. Of course, the flow rate of TEOS, the flow rate of the added gas, the irradiation time, the pressure inside the processing chamber, the distance between the lamp and the susceptor, etc. are appropriately selected according to the desired film quality, film thickness and the like.
The oxygen of this added gas becomes radical oxygen or ozone by the photon energy of excimer light, and decomposed TE
It is removed by reacting with carbon and the like in OS. Therefore, in the oxide film 10 to be formed, a high-quality oxide film 10 containing a small amount of organic oxides derived from carbon or the like of TEOS is formed. Further, in the vicinity of the excimer light extraction window 6 in the processing chamber 1, since the illuminance of the excimer light is strong as much as it is close to the excimer lamp 5, more radical oxygen or ozone is generated, and the oxide film 10a on the excimer light extraction window 6 is generated. Is more effectively suppressed.

Using the insulating film forming apparatus of FIG. 1, TEOS gas is turned on / off as shown in FIG. 2 under substantially the same conditions as described above.
It can also be supplied off-system. That is, during the excimer light irradiation, TEOS is digitally turned on / off every 1 second to 10 minutes, and TEOS is intermittently supplied. As a result, when the TEOS gas is supplied, the oxide film 10 on the wafer 9 is
Are formed, and when the TEOS gas is not supplied, the organic impurities are removed by the photon energy of excimer light.
Increasing the OFF time has the effect of removing organic impurities. When 5 to 1000 ml of the additive gas is introduced at the same time, the oxide film 10 with a small amount of organic impurities is obtained as described above, and the formation of the oxide film 10a on the excimer light extraction window 6 is suppressed.

[0017]

Example 1 An oxide film was formed using the oxide film forming apparatus shown in FIG. First, the processing chamber 1 is 1E-5 Tor with the vacuum pump 3.
pulled to r. Next, liquid TEOS was vaporized by a vaporizer and 50 ml was introduced into the processing chamber 1 through the gas supply pipe 4. At the same time 50 ml of oxygen gas as additional gas
Was introduced into the processing chamber 1 through the gas supply pipe 4a. The internal pressure of the processing chamber 1 was maintained at 0.6 Torr. An excimer lamp filled with rare gas xenon was used as the excimer lamp 5, and synthetic quartz was used as the excimer light extraction window 6. The distance between the lamp 5 and the susceptor 8 was 15 mm. In this state, the excimer lamp 5 was irradiated for 30 minutes.

[0018]

Example 2 Under the same conditions as in Example 1, as an additive gas,
Nitric oxide was used instead of oxygen gas.

[0019]

Comparative Example 1 A film was formed under the same conditions as in Example 1 without using an additive gas. In this case, the internal pressure was 0.3 Torr, and the TEOS partial pressure was the same as that when using the additive gas of Example 1.

[0020]

Test Example 1 For Example 1 and Comparative Example 1, the illuminance (window haze) and the film forming rate before and after the treatment were measured. For measuring the illuminance, an illuminance monitor for excimer light irradiation device (UIT-15
0 / VUVS-172: manufactured by USHIO INC., And a spectroscopic ellipsometry method is used for measurement of film formation.
It was measured with a V1250SE film thickness meter (manufactured by KLA Tencor). The illuminance measurement was performed immediately before and after the film formation under the synthetic quartz window, and the film thickness was measured on a silicon 6 inch wafer at 49 points as an oxide film (N = 1.46). The results are shown in Table 1.

[0021]

[Table 1]

As is clear from Table 1, the illuminance difference before and after the treatment is about half, and the film forming rate is about 10 times on average, depending on whether or not the additive gas is used. It is considered that this is because the oxygen gas becomes radical oxygen or ozone by the excimer light and suppresses the deposition of the oxide film 10a on the excimer light extraction window 6.

[0023]

TEST EXAMPLE 2 The oxide films of Examples 1 and 2 and Comparative Example 1 were analyzed by Fourier transform infrared spectroscopy (FT-IR). As the FT-IR analyzer, IR-EPOCH manufactured by Newly Instruments Co., Ltd. was used.
The measurements were taken at the center point of a 6 inch wafer of silicon.
The results are shown in FIG. 3 (Example 1), FIG. 4 (Example 2) and FIG.
This is shown in (Comparative Example 1). As you can see from these figures,
In Examples 1 and 2 using the additive gas, the amount of the carbon compound was about the trace level as compared with Comparative Example 1 not using the additive gas.
It turned out to be extremely small. This also causes oxygen gas to become radical oxygen or ozone by excimer light,
This seems to be the result of the reduction of organic impurities by reacting with carbon and the like generated by the decomposition of S gas.

[0024]

The method for forming a semiconductor element insulating film according to the present invention has the following advantages and can be widely used for a gate insulating film, a low dielectric constant insulating film and the like used in a semiconductor element. In addition to the semiconductor element, it can be applied to a high-quality insulating film coating on a plastic or the like that cannot be subjected to high temperature processing, a high-quality insulating film coating as a metal protective film, and the like. (1) In the photo-CVD method, since low temperature treatment is possible, damage to the object to be treated can be reduced. Particularly in the case of a semiconductor element, higher density wiring and multilayer wiring are possible. (2) Oxygen-containing gas is added and / or TEOS is intermittently supplied to reduce the amount of organic impurities in the oxide film,
It is possible to obtain a high-quality insulating film in which insulation deterioration does not easily occur. (3) In addition, since it is possible to effectively suppress the deposition of the oxide film on the excimer light extraction window member, it is possible to stably obtain a high-quality insulating film over a long period of time.

[Brief description of drawings]

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

FIG. 2 is a conceptual diagram showing an organic oxide film forming gas supply system of Example 2.

FIG. 3 is a chart showing the FT-IR analysis result of the oxide film of Example 1.

FIG. 4 is a chart showing the FT-IR analysis result of the oxide film of Example 2.

5 is a chart showing the FT-IR analysis result of the oxide film of Comparative Example 1. FIG.

[Explanation of symbols]

1 ... Oxide film forming chamber 2 ... pipe 3 ... Vacuum pump 4, 4a ... Gas supply pipe 5 ... Excimer lamp 6 ... Excimer light extraction window 7 ... Support rod 8 ... Susceptor 9 ... Semiconductor element wafer 10, 10a ... Oxide film

Front page continued (73) Patent holder 392021104 Microelectronics Service Co., Ltd. 19370 Shimodajima, Sadohara-cho, Miyazaki-gun, Miyazaki Prefecture (73) Patent holder 598049746 Miyazaki Daishin Canon Co., Ltd. 4308-1, Takagi, Kijo-cho, Koyu-gun, Miyazaki Prefecture (73) Patent holder 391011700 Miyazaki Prefecture Miyazaki Prefecture Miyazaki City 2-10-1, Tachibana-dori Higashi (73) Patent holder 390008855 Miyazaki Oki Electric Co., Ltd. Miyahara Prefecture Kiyotake-cho, Kiyotake-cho 727 Kihara (73) Patent holder 000000295 Oki Electric Industry Co., Ltd. Toranomon 1-7-12 Minato-ku, Tokyo (72) Inventor Hiroshi Kurosawa 38, Saigochu, Myodaiji-cho, Okazaki-shi, Aichi Okazaki National Institute for Collaborative Research (72) Inventor Yokotani Atsushi, 1-chome, Kibadai Nishi, Gakuen, Miyazaki City, Miyazaki Prefecture Inventor, Faculty of Engineering, Miyazaki University (72) Hiroyuki Muto 19370 Shimodajima, Sadohara-cho, Miyazaki-gun, Miyazaki Prefecture Miyazaki Machine Design Co., Ltd. (72) Invention Miyano Junichi Miyazaki Prefecture Miyazaki District 19370 Shimodajima, Tsuchihara-machi, Miyazaki Machine Design Co., Ltd. (56) Reference JP-A-3-271372 (JP, A) JP-A-9-82696 (JP, A) JP-A-8-134654 (JP, A) ) N. Takezoe, Applied Surface Science, United States, Volumes 138-139, p. 340-343 (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 16/00-16/56 H01L 21/316

Claims (4)

(57) [Claims] The presence of 1. A organic oxide film forming gas, in forming an insulating film on the object surface to be treated by the excimer light, et
An organic oxide film forming gas is intermittently supplied from the gas supply pipe (4) during the irradiation of the xima light , and a gas containing oxygen is added from the gas supply pipe (4a) when the organic oxide film forming gas is not supplied. A method for forming an insulating film, comprising: 2. The method for forming an insulating film according to claim 1, wherein the object to be processed is a semiconductor element. 3. The method for forming an insulating film according to claim 1, wherein the organic oxide film forming gas is tetraethyl orthosilicate (Si (C ₂ H ₅ O) ₄ ). 4. 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 (N ₂ O). Method of forming a film.