JP3384274B2 - Method of removing unnecessary oxide glass 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 removing an unnecessary porous oxide glass film, and more particularly, to flame deposition (Frame Hydrolysis Deposition).
ion (FHD) method, in a porous oxide glass film manufacturing apparatus for forming a porous oxide glass film on a substrate, glass particles deposited on a portion other than the substrate surface inside the apparatus can be easily and surely removed. The invention relates to a method for removing an unnecessary oxide glass film.

[0002]

2. Description of the Related Art An optical waveguide has a structure in which an underclad layer, a core layer and an overclad layer are laminated on a substrate, and a silicon (Si ) Or quartz is used. As a device of such an optical waveguide,
A beam splitter that splits the light into many, an optical switch that switches the signal to a desired line, and in the future, in the optical subscriber system, each household will be provided with a function of demultiplexing / multiplexing optical signals on a Si substrate. ONU (Optical Network Unit) with laser diode (LD), photodiode (PD), etc. integrated with the optical waveguide
Is expected to be introduced, for example, "Applica
tion of planar lightwave
circuit platform to hybrid
d integrated optical WDM
transmitter / receiver modu
le ”(Y. Yamada et al., Select
ron. Lett. 31 (16), 1366-1367.
(1995)) and other developments are already underway.

The manufacturing process of an optical waveguide will be described by taking an example of using silicon (Si) as a substrate for forming such an optical waveguide. To manufacture an optical waveguide on a Si substrate, an underclad on the Si substrate is used. A glass layer having a thickness of about 20 μm is formed, a core layer through which light is guided is formed on the underclad layer, and the core layer is processed into a light guiding pattern by lithography and anisotropic etching. Later, a thickness of 30 will be the overclad layer
This is performed by forming a glass layer having a thickness of μm or more. Flame deposition (FHD) method, electron beam evaporation method, sputtering, plasma CVD method and the like are known as methods for forming these glass layers, but the glass layer having a thickness of several tens of μm is generally produced by the flame deposition method. Is preferred.

The flame deposition method described above is, for example, "Silica".
waveguides on silicon an
d ther application to in
integrated-optic component
s "(M. Kawachi, Optical and
Quantum Electronics 22, 39
1-416 (1990)), using the oxide glass film production apparatus 10 as shown in FIG. 1, Si, G
Halides such as e, Br, and P are supplied to the oxyhydrogen flame burner 11 to generate fine glass particles, which are spray-deposited on the substrate 14 placed on the rotatable table 13 to form a porous oxide. It is a method of forming a transparent glass film on a substrate by forming a glass fine particle film layer and sintering it in an electric furnace (not shown) at a temperature of 1200 to 1400 ° C.

In this case, as shown in FIG. 1, when a substrate is mounted on a rotatably formed table and oxide glass fine particles are deposited on the substrate surface by an oxyhydrogen flame burner, the substrate to be deposited Oxide glass particles are deposited not only on the surface but also on the table on which the substrate is placed. When the substrate is mounted again on this table and the oxide glass particles are repeatedly deposited, the glass particles deposited on the table The (soot) layer peels off, and the peeled soot adheres to the surface of the substrate before deposition. For this reason, it is necessary to remove (clean) the glass fine particle layer deposited on the table after the deposition on the substrate is completed and the deposited substrate is taken out. The removal is performed by scraping off the oxide glass layer from the table and exhausting it to the outside of the system, which causes the following problems.

(1) When the oxide glass fine particle layer is peeled off from the table, all of the peeled soot layer cannot be exhausted and removed, and the soot remains in the chamber and scatters in the deposition chamber. When the substrate was placed on the table and deposited while leaving this state, the substrate was left in the chamber as the temperature of the atmosphere in the chamber increased because the substrate was heated to a high temperature by the heater installed under the table. Soot may fly (scatter) in the system and adhere to the substrate surface. Further, when the soot adheres to the ceiling of the chamber, it may fall due to some disturbance and adhere to the substrate surface.

When the soot adheres to the surface of the substrate in this manner, the soot remains as a foreign matter even after the deposition and sintering, and the film thickness locally increases at the location of the foreign matter (the thickness distribution varies). Variation occurs), a good surface condition cannot be obtained, and the appearance may be impaired.

(2) When exhausting the oxide glass fine particle layer peeled from the table to the outside of the system, open the chamber door,
It is necessary to expose the deposition atmosphere to an atmosphere outside the system, and at this time, foreign matter existing outside the system may be scattered, and foreign matter from an operator during the soot layer removing operation may be mixed into the system. When such foreign matter adheres to the interface of the substrate or the interface of the porous oxide glass layer after deposition, it may cause foaming during the heat treatment or cause loss when the optical waveguide pattern is actually formed. There are cases.

The present invention has been made in view of the above circumstances, and easily and reliably removes unnecessary glass fine particles deposited on a portion other than the substrate surface in the chamber of the above-described porous oxide glass film manufacturing apparatus. An object of the present invention is to provide a method for removing an unnecessary oxide glass film, which is capable of maintaining a clean state in the chamber and capable of forming a high-quality porous oxide glass film with a high yield.

[0010]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention have found that other than the substrate surface in the chamber of the porous oxide glass film manufacturing apparatus. We found that the unnecessary oxide glass film can be easily and surely removed by irradiating it with a flame supplied with a fluorine compound to the oxyhydrogen flame burner when removing the unnecessary oxide glass film such as glass particles deposited on the part. .

When a substrate is placed on a table, the substrate is heated by a heater provided under the table, and oxide glass fine particles are sprayed and deposited on the substrate from an oxyhydrogen flame burner to form a glass fine particle layer. Even if the glass particles not deposited on the substrate surface are removed by suction with the exhaust pipe, the glass particles are deposited on the table other than the substrate surface and on the exhaust pipe inner wall. When removing glass fine particles, by supplying a fluorine compound to the oxyhydrogen flame burner, HF is generated by the reaction between the fluorine compound and the oxyhydrogen flame, and H ₂ O is generated by the oxyhydrogen flame. in state H is preferably in the deposited table or on the exhaust pipe wall oxide glass particles oxyhydrogen flame comprising ₂ O to the oxide glass fine particles are held in the 100 ° C. or less and By the irradiation, the HF reacts with the glass particles, and the glass particles deposited on a portion other than the substrate surface inside the chamber of the porous oxide glass film manufacturing apparatus can be easily and surely removed, and the inside of the chamber can be kept clean. The present invention has been completed by discovering that a high quality porous oxide glass film can be formed with good yield.

The mechanism of the removing method of the present invention is as follows.
This is not due to etching by F ions or F radicals as is done by anisotropic etching of the core. That is, while the temperature of the oxyhydrogen flame is a few thousand hundreds of degrees Celsius, the energy normally used for etching with an F-based gas is several hundred V, so it is considered that the mechanism of energy proceeds with an etching mechanism using an F-based gas. Hateful. Furthermore, when the table temperature was 400 ° C., cleaning of the soot on the table did not occur at all. On the other hand, the table temperature is 1
By lowering the temperature to 00 ° C or lower, soot peeling and cleaning effects were recognized. This is due to the H produced by the oxyhydrogen flame.
Since 2 O tends to remain on the table, the mechanism of the removing method of the present invention is not etching by F ions or F radicals, but Si by HF aqueous solution.
It is considered to be a dissolution reaction of O ₂ .

When the soot on the table is irradiated with the oxyhydrogen flame supplied with the fluorine compound for cleaning, not only the table but also the inner wall of the exhaust pipe can be cleaned at the same time. That is, when the glass particles are repeatedly deposited on the surface of the substrate, soot adheres to the inner wall of the exhaust pipe. If the amount of the soot adhered is large, the soot particles adhered to the inner wall due to some disturbance fall on the table or in the chamber, which causes the generation of foreign matter. Therefore, it is necessary to regularly clean the inner wall of the exhaust pipe. However, in the removal method of the present invention, the soot on the inner wall of the exhaust pipe can be removed at the same time by sucking the oxyhydrogen flame containing HF and H ₂ O through the exhaust pipe, and the exhaust pipe is taken out of the chamber one by one. This eliminates the trouble of removing the soot adhering to, and is advantageous in terms of maintenance of the device.

Therefore, according to the present invention, the oxide glass fine particles are sprayed and deposited from the oxyhydrogen flame burner onto the substrate placed on the table, and the oxide glass fine particles deposited on unnecessary portions other than the substrate surface are deposited. When removing
A method for removing an unnecessary oxide glass film, which comprises supplying a fluorine compound to the burner and irradiating a flame containing hydrogen fluoride and water to the oxide glass fine particles deposited on the unnecessary portion from the burner. To do.

In this case, it is preferable that the oxide glass fine particles deposited on the unnecessary portions are subjected to the above treatment at a temperature of 100 ° C. or lower, and the unnecessary oxide glass fine particles are on the table or in the exhaust pipe. Oxide particles deposited on the walls are mentioned.

The present invention will be described in more detail below.
The present invention, by supplying a fluorine compound to the oxyhydrogen flame burner, to generate HF by the reaction of the fluorine compound and the oxyhydrogen flame, and by irradiating the unnecessary glass particles with a flame containing this HF and water, The glass fine particles are removed.

The fluorine compound used here is not particularly limited as long as it decomposes by a reaction with an oxyhydrogen flame, but from the viewpoint of safety, it may be a substance which is inert even when exposed to the atmosphere, for example, SF ₆ , CHF _{3 and the} like can be mentioned.

When supplying the above-mentioned fluorine compound to the burner, the flow rate thereof is not particularly limited. Considering the time required for cleaning, it is preferably 1 L / min or more, but may be less than 1 L / min.

In the present invention, it is effective that the unnecessary oxide glass fine particles to be removed are irradiated with the flame preferably at a temperature of 100 ° C. or lower. That is, the removal mechanism of soot (oxide glass fine particles) is not a gas phase reaction, but HF
Since the reaction is the dissolution reaction of SiO ₂ by the aqueous solution, the table temperature is the same as that at the time of depositing the glass particles, 400 to 600
At ° C, no cleaning is done on the table. However, a cleaning effect may be recognized inside the exhaust pipe whose temperature is lower than that of the table.

That is, for the purpose of removing the soot adhering to the table, the table temperature, that is, the soot temperature, is 100 ° C. or less, preferably 50 ° C., at which water does not evaporate.
When the purpose is to remove the soot adhering to the inner wall of the exhaust pipe, the amount of soot deposited on the inner wall of the exhaust pipe is 10 or less.
It may be 0 ° C or lower.

In the present invention, the oxide glass fine particles can be deposited on the substrate by using the porous oxide glass film production apparatus shown in FIG. 1, and the glass fine particle layer having a desired thickness is formed on the substrate. After the deposition, the supply of the glass raw material was stopped, the heater under the table was turned off, the table temperature was lowered to 100 ° C or lower, the deposited substrate was taken out of the apparatus, and the cleaning dummy Si was put on the taken out portion. It is preferable to place a wafer and supply a fluorine compound as a cleaning material at a constant flow rate to the oxyhydrogen flame burner used for deposition. The surface of the table and the dummy Si wafer are irradiated with the oxyhydrogen flame supplied with the fluorine compound by the same method as that for depositing the glass particles. In this case, by sucking the burner supplied with the fluorine compound through the exhaust pipe, the inner wall of the exhaust pipe can be cleaned even when the table temperature is high.

The substrate used in the present invention is preferably made of silicon (Si) or quartz, and its shape and size are not particularly limited.

According to the method for removing an unnecessary oxide glass film of the present invention, the glass particles deposited on the portion other than the substrate surface can be easily and surely removed, and the chamber can be kept clean at all times. It is possible to form an oxide glass film having a uniform film thickness distribution and a good surface condition.

[0024]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 Oxide glass fine particles were deposited on a substrate using the apparatus shown in FIG. The rotary table 13 has a diameter of 80 cm and a diameter of 1
A plurality of (9 in FIG. 1) silicon (Si) substrates 14 having a thickness of 0 cm and a thickness of 1 mm were mounted. These substrates are preheated to a substrate temperature of about 600 ° C. by a heater (not shown) below the rotary table 13.

While rotating the table 13 on which the substrate is mounted in a fixed direction (arrow L in the figure) at a rotation speed of 5 rpm,
While supplying the glass raw material from the supply pipe (not shown) to the oxyhydrogen flame burner, the burner was reciprocated along the radial direction of the table under the conditions of a stroke length of 16 cm and a moving speed of 1 cm / sec to remove glass particles. It was spray deposited on the substrate. At this time, the excess glass fine particles not deposited on the substrate are sucked out of the system by the exhaust pipe. SiCl ₄ , BBr ₃ and POCl ₃ were used as glass raw materials, and the respective supply rates were 150 cc / min and 20 c.
It was supplied into the flame so as to be c / min and 20 cc / min.

Desired thickness on substrate (about 200 μm)
After depositing the glass particulate layer, the supply of the glass raw material was stopped, the heater under the table was turned off, and the table temperature was sufficiently lowered to 40 ° C. After the table was sufficiently cooled, the deposited substrate was taken out of the apparatus, and a cleaning dummy Si wafer was placed on the taken out portion. SF ₆ as a cleaning raw material was supplied to the oxyhydrogen flame burner used for deposition at a flow rate of 1 L / min. The surface of the table and the dummy wafer were irradiated with the oxyhydrogen flame supplied with SF ₆ by the same method as in the deposition of the glass particles.

At this time, the glass fine particle layer deposited on the table was quickly dissolved, and the exposure of the table surface could be confirmed. At this time, it was confirmed that not only the surface of the table but also the inner wall of the exhaust pipe to which the soot layer had adhered was cleaned.

After cleaning, a plurality of sheets of S are placed on the table.
The i-wafer was set and glass particles were deposited by the same process, but no foreign matter was found to adhere to the surface of the Si substrate.

[Example 2] The oxide glass fine particles were deposited on the substrate in the same manner as in Example 1, and after the deposition was completed,
The supply of glass raw materials was stopped, and the heater under the table was turned off. While the table temperature is not cold enough (4
The substrate deposited at 00 ° C. was taken out, and a cleaning dummy Si wafer was placed on the taken-out portion.

SF ₆ as a cleaning raw material was supplied to the oxyhydrogen flame burner used for deposition at a flow rate of 1 L / min. The surface of the table and the dummy wafer were irradiated with the oxyhydrogen flame supplied with SF ₆ by the same method as in the deposition of the glass particles.

At this time, almost no change was recognized in the state of the glass fine particle layer deposited on the table. Up to 5 times the deposition time of the glass particle layer SF ₆
The irradiation of the oxyhydrogen flame was continued, but there was no change in the appearance of the glass fine particle layer on the table. However, it was confirmed that the inside of the exhaust pipe was cleaned because the temperature was sufficiently lower than that on the table.

[Comparative Example] The oxide glass fine particles were deposited on the substrate in the same manner as in Example 1. After the deposition was completed, the supply of the glass raw material was stopped, the heater under the table was turned off, and the table temperature was changed. Was low enough. After the table was sufficiently cooled, the deposited substrate was taken out, the chamber lid was opened, the soot deposited on the table was mechanically scraped off, and the separated soot was removed by a vacuum cleaner. After removing the soot on the table, a plurality of 4 ″ φ Si wafers were set again on the table, and the substrate was heated by the heater under the table. It seems that soot particles were peeled off on the surface of several Si wafers during this heating. In addition, it was confirmed that the foreign matter adhered to the substrate was adhered, and that the glass particles were deposited and the substrate after the heat treatment was partially fired and foreign matter was observed.

[0034]

EFFECTS OF THE INVENTION According to the present invention, it is possible to easily and surely remove the glass fine particles deposited on unnecessary portions other than the substrate surface, and to have a uniform film thickness distribution and a good surface condition. The glass film can be formed with high yield.

[Brief description of drawings]

FIG. 1 is a partial schematic view of an apparatus for producing a porous oxide glass film according to an embodiment of the present invention.

[Explanation of symbols] 10 Porous oxide glass film manufacturing equipment 11 burners 12 Exhaust pipe 13 tables 14 board

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Ejima 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd., Institute of Precision Materials (72) Inventor Kazuo Kamiya Isobe, Gunma Prefecture 2-chome No. 13-1 Shin-Etsu Chemical Co., Ltd. Precision Materials Research Laboratory (56) References JP-A-62-187133 (JP, A) JP-A-62-291034 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C03B 8/04 C03B 19/14 C03B 20/00 C03B 37/00-37/16 G02B 6/12 H01L 21/306

Claims (3)

(57) [Claims] 1. A method of spraying oxide glass particles from an oxyhydrogen flame burner onto a substrate placed on a table to deposit the oxide glass particles and removing oxide glass particles deposited on an unnecessary portion other than the substrate surface, A method for removing an unnecessary oxide glass film, comprising supplying a fluorine compound to the burner, and irradiating a flame containing hydrogen fluoride and water to the oxide glass fine particles deposited on the unnecessary portion from the burner. 2. The method according to claim 1, wherein the oxide glass fine particles deposited on the unnecessary portion are irradiated with a flame containing hydrogen fluoride and water at a temperature of 100 ° C. or lower. 3. The oxide glass fine particles deposited on the unnecessary portion are deposited on the inner wall of an exhaust pipe which is disposed on the table or in the vicinity of the burner and sucks and removes the oxide glass fine particles not deposited on the substrate surface. The method according to claim 1 or 2, wherein the oxide fine particles are formed.