JPS63204616A - How to clean the reaction chamber - Google Patents

Abstract

PURPOSE:To sufficiently clean the title reaction chamber in a short period and to obtain the simple washing process having no secondary contamination due to ion bombardment, by a method wherein a reaction chamber is etched using an optically pumped halogen radical. CONSTITUTION:In a growing process, a-Si is deposited on the substrate 3 to be grown and, at the same time, it is adhered to the inside of a light- transmitting window 4. At the point of time when washing is necessary, reaction gas is stopped, Cl2 is introduced into a chamber 1, and when an ultraviolet ray source 5 is lighted up, chlorine radical Cl* is generated in the reaction chamber 1. Cl2 efficiently absorbs ultraviolet rays of wavelength of about 300 nm or less, and it generates Cl*, the Cl* reacts with Si, deposited on the light-transmitting window 4 or SiHx and the like, and as they are removed, the reaction chamber can be cleaned. In this cleaning process, as no ions are generated in the reaction chamber 1, the inner wall of the chamber is not sputtered. Accordingly, there is no possibility of having the secondary contamination. As a result, the simple cleaning process with which the reaction chamber is sufficiently cleaned in a short period can be obtained.

Description

[Detailed Description of the Invention] [Summary] A method for forming a thin film or cleaning a reaction chamber of an etching device using optically excited halogen radicals is proposed, which eliminates the need for removing the reaction chamber and cleaning it with chemicals, thereby simplifying the process. Make sure it can be thoroughly cleaned.

[Industrial application field]

The present invention relates to a method for cleaning a reaction chamber of a thin film forming or etching apparatus.

Conventionally, reaction chambers that perform thin film formation using chemical vapor deposition (CVD), sputtering, or thermal oxidation, or patterning or etching processing such as plasma etching or reactive ion etching (RIE), have been used for a certain period of time before being used. It is essential to stop the reaction chamber and clean the inner walls of the reaction chamber, and in particular, the reaction chamber when used for manufacturing semiconductor devices must be managed to maintain an extremely clean state.

This is due to contamination of the inner wall of the reaction chamber, resulting in the generation of fine particles, falling flakes, or 2.
This is because secondary contamination directly affects the yield of the product.

[Conventional technology and Problems that the invention attempts to solve]

Conventionally, methods such as periodically cleaning the inner wall of the reaction chamber with a solvent, cleaning with a chemical, or etching using active gas plasma have been used.

However, as the device becomes larger, it becomes difficult to remove the reaction chamber from the device, and there are also problems in that it is not possible to thoroughly clean the details.

Furthermore, in the case of using plasma, the conditions for plasma generation are narrow and uniform cleaning is not possible, and there is also the problem of reverse contamination due to ion bombardment.

In particular, in CvD devices that use optical energy, because the outer shell light is irradiated through a light-transmitting window provided in the reaction chamber, reaction products that adhere to the window block the light.
There is a problem that continuous processing is not possible.

For this reason, methods such as applying oil that does not adsorb reactive gases to the window or etching the window with plasma have been used, but these methods have not been sufficiently effective.

[Means for solving problems]

The above problem can be solved by a reaction chamber cleaning method in which deposits attached to the inner wall of the reaction chamber are etched away using halogen radicals generated by optical excitation.

For example, a chlorine radical is used as the halogen radical.

Further, the cleaning effect can be enhanced by mixing an inert gas into the halogen radical.

[Effect]

The present invention utilizes the results of the inventor's confirmation that the reaction chamber can be sufficiently cleaned in a short time by etching it with photo-excited halogen radicals.

This method provides a simple cleaning process without secondary contamination due to ion bombardment.

〔Example〕

An embodiment of the present invention will be described with respect to a photo-CVD apparatus for depositing amorphous silicon (a-S i ).

FIG. 1 is a sectional view of a photo-CVD apparatus for explaining the present invention in detail.

In the figure, a susceptor 2 having a built-in heater is provided in a reaction chamber 1, and a growth substrate 3 is placed on the susceptor 2.

A light transmitting window 4 made of synthetic quartz is provided in the reaction chamber 1 facing the growth substrate 3, through which an ultraviolet light source 5 is transmitted.
Ultraviolet light is irradiated onto the growth substrate 3.

A reaction gas such as disilane (SizH6) can be introduced into the reaction chamber 1 through the reaction gas inlet 6, and a halogen gas such as chlorine (CtZ) can be introduced into the reaction chamber 1 as a cleaning gas through the halogen gas introduction lower.

In the growth process, a-3t is deposited on the growth substrate 3 and also adheres to the inside of the light transmission window 4 at the same time.

When cleaning becomes necessary, the reaction gas is stopped, Ch is introduced into the reaction chamber 1, and the ultraviolet light source 5 is turned on to generate chlorine radicals CI* in the reaction chamber 1.

C12 efficiently absorbs ultraviolet light with a wavelength of about 300 nm or less and generates CI'', and C1'' reacts with Si, SiH, etc. deposited on the light transmission window 4 and removes them, making cleaning possible. become.

In this cleaning step, since no ions are generated within the reaction chamber 1, the inner wall of the chamber is not sputtered. Therefore, there is no need to worry about secondary contamination.

Further, the chamber internal pressure is desirably reduced to several tens of Torr, but is not limited to this.

Furthermore, by introducing another gas with a large atomic radius, such as argon (Ar), into the halogen gas, scattering of CI'' can be enhanced and detailed cleaning can be performed efficiently.

FIG. 2 is a sectional view of a horizontal CVD surface illustrating another embodiment.

This apparatus is, for example, an apparatus for depositing crystalline Si, and 10 is a heater for crystalline Si deposition.

In conventional cleaning of such an apparatus, the quartz reaction tube of the reaction chamber 1 was removed and chemical cleaning was performed.

In contrast, in the present invention, CI2 is introduced into the quartz reaction tube instead of the reaction gas, and CI'' generated in the ultraviolet irradiation section 8 irradiated by the ultraviolet light source 5 is transferred to the film deposition section 9. CI'' also spreads to areas other than the irradiation section 8, and the entire quartz reaction tube is cleaned.

In the example, CI'' was used as the halogen radical, but the same effect can be obtained by using a fluorine radical (pi) instead.

〔Effect of the invention〕

As described above in detail, according to the present invention, a reaction chamber can be sufficiently cleaned in a short time, and a simple cleaning process without secondary contamination due to ion bombardment can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an optical CVD apparatus for explaining the present invention in detail, and FIG. 2 is a cross-sectional view of a horizontal CVD apparatus for explaining another embodiment. In the figure, 1 is a reaction chamber, 2 is a susceptor, 3 is a growth substrate, 4 is a light transmission window, 5 is an ultraviolet light source, 6 is a reaction gas inlet, 7 is a halogen gas inlet, 8 is an ultraviolet irradiation part, 9 10 is a film deposition section, and 10 is a heater.

Claims (3)

[Claims] (1) Due to halogen radicals generated by photoexcitation,
A method for cleaning a reaction chamber, characterized by etching and removing deposits attached to the inner wall of the reaction chamber. (2) The method for cleaning a reaction chamber according to claim 1, wherein the halogen radical is a chlorine radical. (3) The method for cleaning a reaction chamber according to claim 1, characterized in that an inert gas is mixed into the halogen radical.