JPH10251028A - Method for removing unnecessary oxide glass film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a porous oxide glass film capable of easily and surely removing an oxide glass fine particle deposited on an unnecessary part except the surface of a substrate, uniform in film thickness and excellent in the surface condition in high yield. SOLUTION: At the time of blowing the oxide glass fine particle on the substrate placed on a table from an oxyhydrogen flame burner to deposit and removing the oxide glass fine particle deposited on the unnecessary part except the surface of the substrate, a fluorine compound is supplied to the burner and a flame containing hydrogen fluoride and water is applied to the oxide glass fine particle deposited on the unnecessary part from the burner.

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 a method for removing a flame-deposited porous glass film.
In a porous oxide glass film manufacturing apparatus for forming a porous oxide glass film on a substrate by an ion (FHD) method, glass fine particles deposited on portions other than the substrate surface in the apparatus are easily and reliably removed. And 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 under cladding layer, a core layer and an over cladding layer are laminated on a substrate, and the substrate on which the optical waveguide is formed is made of silicon (Si). ) Or quartz is used. Such optical waveguide devices include:
A beam splitter that splits light into a number of parts, an optical switch that switches a signal to a desired line, and in the future, in an optical subscriber system, each home will have a function of demultiplexing / multiplexing an optical signal on a Si substrate. ONU (Optical Network Unit) integrating laser diode (LD), photodiode (PD), etc. with optical waveguide
Is expected to be introduced, for example, "Applica
Tion of planar lightwave
circuit platform to hybri
d integrated optical WDM
transmitter / receiver mod
le "(Y. Yamada et al., Elect.
ron. Lett. 31 (16), 1366-1367
(1995)) and the like.

[0003] The manufacturing process of an optical waveguide will be described using silicon (Si) as an example of a substrate on which such an optical waveguide is formed. To manufacture an optical waveguide on a Si substrate, an under clad is formed on the Si substrate. A glass layer having a thickness of about 20 μm as a layer was formed, a core layer through which light was guided was formed on the under cladding layer, and the core layer was processed into a light waveguide pattern by lithography and anisotropic etching. Later, a thickness of 30 to become an over cladding layer
This is performed by forming a glass layer having a thickness of at least μm. As a method for forming these glass layers, a flame deposition (FHD) method, an electron beam evaporation method, a sputtering method, a plasma CVD method, and the like are known, and a glass layer having a thickness of several tens of μm is generally formed by a flame deposition method. Is preferred.

[0004] The flame deposition method described in, for example, “Silica
waveguides on silicon an
d their application to in
integrated-optic component
s "(M. Kawachi, Optical and
Quantum Electronics 22,39
1-416 (1990)), using an oxide glass film manufacturing apparatus 10 as shown in FIG.
e, Br, P, and other halides are supplied to the oxyhydrogen flame burner 11 to generate glass fine particles, which are sprayed and deposited on a substrate 14 mounted on a rotatable table 13 to deposit porous fine particles. This is a method in which a transparent glass film is formed on a substrate by forming a glass particle layer and sintering the layer at 1200 to 1400 ° C. in an electric furnace (not shown).

In this case, as shown in FIG. 1, when the substrate is mounted on a rotatable table and oxide glass fine particles are deposited on the substrate surface by an oxyhydrogen flame burner, the substrate to be deposited is deposited. Oxide glass particles are deposited not only on the surface but also on the table on which the substrate is placed. If the substrate is mounted on this table again and deposition of the oxide glass particles is repeated, the glass particles deposited on the table There is a problem that the (soot) layer peels off and the peeled soot adheres to the substrate surface before deposition. For this reason, the glass fine particle layer deposited on the table has to be removed (cleaned) after the deposition on the substrate is completed and the deposited substrate is taken out. Conventionally, the glass fine particle layer deposited on the table is usually removed. The removal is performed by rubbing the oxide glass layer from the table and exhausting the oxide glass layer out of the system. Therefore, there are 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 is scattered in the deposition chamber. When the substrate was mounted on the table and deposition was carried out while leaving this state, the substrate was heated to a high temperature by the heater installed at the lower part of the table, so that the substrate was left in the chamber as the temperature of the atmosphere in the chamber rose. The 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.

[0007] When soot adheres to the substrate surface in this way, this soot exists as foreign matter even after deposition and sintering, and the film thickness locally increases at the place where the foreign matter is present (in the film thickness distribution). (Variation occurs), a good surface state 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. 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 causes foaming during heat treatment or causes loss when an optical waveguide pattern is actually formed. There are cases.

The present invention has been made in view of the above circumstances, and it is possible to easily and surely remove unnecessary glass particles deposited on a portion other than the substrate surface in a chamber of a porous oxide glass film manufacturing apparatus as described above. It is an object of the present invention to provide a method for removing an unnecessary oxide glass film, which can maintain a clean state in a chamber and form a high-quality porous oxide glass film with high yield.

[0010]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that the surface of the apparatus for manufacturing a porous oxide glass film has a surface other than the substrate surface in the chamber. When removing unnecessary oxide glass films such as glass fine particles deposited on the part, it was found that unnecessary oxide glass films could be easily and reliably removed by irradiating the oxyhydrogen flame burner with a flame supplied with a fluorine compound. .

When a substrate is placed on a table, the substrate is heated by a heater provided below the table, and oxide glass particles are sprayed and deposited on the substrate from an oxyhydrogen flame burner to form a glass particle layer. Even if the glass fine particles not deposited on the substrate surface are removed by suction using an exhaust pipe, the glass fine particles are deposited on a table other than the substrate surface or on the inner wall of the exhaust pipe. In the case of removing glass 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, HF reacts with the glass particles, and the glass particles deposited on portions other than the substrate surface in the chamber of the porous oxide glass film manufacturing apparatus can be easily and reliably removed, and the inside of the chamber is kept clean. And found that a high-quality porous oxide glass film can be formed with good yield, and completed the present invention.

The mechanism of the removal method of the present invention is as follows.
This is not due to etching by F ions or F radicals as performed in the anisotropic etching of the core. That is, while the temperature of the oxyhydrogen flame is several hundreds of degrees Celsius, the energy normally used for etching with the F-based gas is several hundred volts. Hateful. Further, when the table temperature was 400 ° C., no cleaning of the soot on the table occurred. On the other hand, if the table temperature is 1
By lowering the temperature to 00 ° C or lower, soot peeling and cleaning effects were recognized. This means that the H
Since 2O tends to remain on the table, the mechanism of the removal method of the present invention is not etching by F ions or F radicals, but by Si
This is considered to be a dissolution reaction of O ₂ .

Further, when the soot on the table is irradiated with an oxyhydrogen flame to which the fluorine compound has been supplied 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 deposition of the glass particles on the substrate surface is repeated, soot adheres to the inner wall of the exhaust pipe. If the amount of soot adhering is large, soot particles adhering to the inner wall due to some disturbance will fall on the table or in the chamber, causing foreign matter to be generated. Therefore, it is necessary to periodically 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 simultaneously removed 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 and the inner wall is removed. This eliminates the need for removing soot adhering to the device, and is advantageous in terms of maintenance of the device.

Accordingly, the present invention provides a method of spraying and depositing oxide glass particles on a substrate placed on a table from an oxyhydrogen flame burner and depositing the oxide glass particles on unnecessary portions other than the substrate surface. Upon removal,
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. I do.

In this case, it is preferable to perform the above-mentioned treatment in a state where the oxide glass fine particles deposited on the unnecessary portion are kept at 100 ° C. or less, and the unnecessary oxide glass fine particles may be on the table or in the exhaust pipe. Oxide fine particles deposited on the wall may be mentioned.

Hereinafter, the present invention will be described in more detail.
The present invention supplies a fluorine compound to an oxyhydrogen flame burner, thereby generating HF by a reaction between the fluorine compound and the oxyhydrogen flame, and irradiating the flame containing HF and water to unnecessary glass fine particles, thereby reducing the unnecessary glass particles. This is for removing glass particles.

Here, the fluorine compound used 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. SF ₆ , CHF _{3 and the} like.

When the fluorine compound is supplied to the burner, the flow rate 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 to perform the above-mentioned flame irradiation in a state where the unnecessary oxide glass fine particles to be removed are preferably at 100 ° C. or lower. That is, the soot (oxide glass fine particle) removal mechanism is not a gas phase reaction, but HF.
Since the reaction is a dissolution reaction of SiO ₂ by an aqueous solution, the table temperature is 400 to 600 which is the same as that at the time of depositing the glass particles.
If the temperature is ° C, no cleaning is performed on the table. However, a cleaning effect may be recognized inside the exhaust pipe having a lower temperature than the table.

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

In the present invention, the deposition of the oxide glass fine particles on the substrate can be performed by using the porous oxide glass film manufacturing apparatus shown in FIG. 1, and the glass fine particle layer having a desired thickness is formed on the substrate. After the supply of the glass raw material was stopped, the heater at the lower part of the table was turned off, the table temperature was sufficiently lowered to 100 ° C. or less, the deposited substrate was taken out of the apparatus, and a dummy Si for cleaning was placed on the taken-out part. It is preferable to place a wafer and supply a fluorine compound at a constant flow rate as a cleaning raw material to the oxyhydrogen flame burner used for deposition. The table and the surface of the dummy Si wafer are irradiated with the oxyhydrogen flame to which the fluorine compound has been supplied in the same manner as in the deposition of the glass particles. In this case, by sucking the burner to which the fluorine compound has been supplied by the exhaust pipe, it is possible to clean the inner wall of the exhaust pipe 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, glass particles deposited on portions other than the substrate surface can be easily and reliably removed, and the inside of the chamber can be always kept clean. Thus, an oxide glass film having a uniform film thickness distribution and a favorable surface condition can be formed.

[0024]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to 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 (9 in FIG. 1) of silicon (Si) substrates 14 having a thickness of 0 cm and a thickness of 1 mm were mounted. These substrates are previously heated to a substrate temperature of about 600 ° C. by a heater (not shown) below the turntable 13.

While rotating the table 13 on which the substrate is mounted in a certain direction (arrow L in the drawing) at a rotation speed of 5 rpm,
While supplying glass material from a supply pipe (not shown) to the oxyhydrogen flame burner, the burner is reciprocated on the substrate under the conditions of a stroke length of 16 cm and a moving speed of 1 cm / sec along the radial direction of the table to remove glass particles. Spray deposited on the substrate. At this time, surplus glass particles not deposited on the substrate are sucked out of the system by an exhaust pipe. SiCl ₄ , BBr _3, and POCl ₃ were used as glass raw materials, and the respective supply amounts were 150 cc / min, 20 c
C / min and 20 cc / min were supplied into the flame.

Desired thickness on substrate (about 200 μm)
After the glass fine particle layer was deposited, the supply of the glass raw material was stopped, the heater at the lower part of the table was turned off, and the table temperature was lowered sufficiently to 40 ° C. After the table was sufficiently cooled, the deposited substrate was taken out of the apparatus, and a dummy Si wafer for cleaning was placed on the taken-out portion. SF ₆ was supplied as a cleaning raw material to the oxyhydrogen flame burner used for the 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 in the same manner as in the deposition of the glass particles.

At this time, the glass fine particle layer deposited on the table was quickly dissolved, and it was confirmed that the table surface was exposed. At this time, it was confirmed that not only the table surface 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
The i-wafer was set, and glass particles were deposited by the same process, but no foreign matter was observed on the surface of the Si substrate.

Example 2 The deposition of oxide glass particles on a substrate was performed in the same manner as in Example 1, and after the deposition was completed,
The supply of the glass raw material was stopped, and the heater below the table was turned off. Before the table temperature is not enough (4
The substrate deposited at (00 ° C.) was taken out, and a dummy Si wafer for cleaning was placed on the taken-out portion.

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

At this time, little change was observed in the state of the glass fine particle layer deposited on the table. SF ₆ up to 5 times the deposition time of the glass particle layer
Was continued to be irradiated with the oxyhydrogen flame supplied, but the state of the glass fine particle layer on the table did not change. However, since the temperature inside the exhaust pipe was sufficiently lower than that on the table, it was confirmed that cleaning was completed.

[Comparative Example] Oxide glass 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 at the lower part of the table was turned off, and the temperature of the table was lowered. Was low enough. After the table was sufficiently cooled, the deposited substrate was taken out, the lid of the chamber was opened, the soot deposited on the table was mechanically scraped, and the peeled soot was removed with a vacuum cleaner. After the soot on the table was removed, a plurality of 4 ″ φ Si wafers were set on the table again, and the substrate was heated by the heater under the table. The soot particles separated on the surface of several Si wafers during the heating were considered. In addition, it was confirmed that foreign matter adhered, and that the glass particles were deposited and the substrate after the heat treatment was partially fired and foreign matter was observed.

[0034]

According to the present invention, it is possible to easily and surely remove glass fine particles deposited on unnecessary portions other than the substrate surface, to obtain a porous oxide having a uniform film thickness distribution and a good surface condition. A glass film can be formed with high yield.

[Brief description of the drawings]

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

[Explanation of symbols]

 Reference Signs List 10 Porous oxide glass film manufacturing apparatus 11 Burner 12 Exhaust pipe 13 Table 14 Substrate

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazuo Kamiya 2-3-1-1, Isobe, Annaka-shi, Gunma Pref. Shin-Etsu Chemical Industry Co., Ltd.

Claims (3)

[Claims] An oxyhydrogen flame burner sprays and deposits oxide glass fine particles onto a substrate placed on a table, and removes oxide glass fine particles deposited on unnecessary portions 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 a flame containing hydrogen fluoride and water is irradiated with the oxide glass fine particles deposited on the unnecessary portion at a temperature of 100 ° C. or less. 3. An oxide glass particle deposited on the unnecessary portion is deposited on an inner wall of an exhaust pipe which is disposed on the table or in the vicinity of the burner and suctions and removes oxide glass particle not deposited on the substrate surface. 3. The method according to claim 1, wherein the oxide particles are prepared.