JPS62136573A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To improve the activation efficiency of the reactive gas in a reaction chamber by selecting only the gas which forms a long-life metastable excitation species and passing the gas through the 1st plasma generating means. CONSTITUTION:This plasma treatment device is formed of the reaction chamber 1, the 1st plasma generating means 5, 6, a means for conducting the metastable excitation species generated therefrom to the reaction chamber 1, a means for introducing the reactive gas into the reaction chamber 1 and the 2nd plasma generating means 11, 12 for activating said gas. The 1st plasma generating means 5, 6 generate the metastable excitation species of >=10ms life. >=1 kinds of rare gas, nitrogen and oxygen are used as the gas for generating the metastable excitation species.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a plasma processing apparatus that performs plasma film formation and plasma etching used in semiconductor processes and the like.

[Background of the invention]

BACKGROUND ART As the manufacturing process of semiconductor devices and the like has progressed towards a dry process, film formation and etching methods using plasma are increasingly being used. As a means of increasing the processing efficiency in such a plasma processing apparatus, a method of providing two plasma generation chambers was devised, and was disclosed in Japanese Patent Publication No. 59-145530,
It is publicly known in No. 9-148326, Town No. 59-191324, etc. In such known examples, the reaction gas first undergoes preliminary decomposition in a first discharge chamber (preliminary chamber),
Thereafter, it is led to a reaction chamber, which is a second discharge chamber.

As a result, the plasma density in the reaction chamber (second discharge chamber) becomes much higher than in the conventional method, and it is said that the processing speed of film formation and etching is improved.

Although the method of preliminarily decomposing the reaction gas in the first discharge chamber (preliminary chamber) is effective as a means of increasing the number of active species in the reaction chamber (second discharge chamber), on the other hand, Many radicals and decomposition products generated in the discharge chamber are transferred to the reaction chamber (
There was a problem in that the cells were inactivated by recombination before entering the second discharge chamber (second discharge chamber). Further, there were also problems such as a large amount of reaction product film adhering to the inner wall of the tube connecting the first discharge chamber and the reaction chamber (second discharge chamber).

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus that solves the above-mentioned problems and improves activation efficiency of reactive gas within a reaction chamber (second discharge chamber).

Another object of the present invention is to provide a plasma processing apparatus in which a film of reaction products hardly adheres to the inner wall of a tube connecting a first discharge chamber and a reaction chamber (second discharge chamber).

[Summary of the invention]

In order to achieve the above object, in the present invention, long-lived metastable excited atoms/molecules are generated in a first discharge chamber, and then the metastable excited atoms/molecules are transferred to a reaction chamber (second discharge chamber). It is characterized in that it guides the excited species and also guides the reactive gas directly to the reaction chamber (second discharge chamber) without passing through the first discharge chamber.

Therefore, the present invention provides a reaction chamber for accommodating a substrate to be processed, a first plasma generating means for generating a metastable excited species, a means for guiding the metastable excited species into the reaction chamber, and a reactive gas introduced into the reaction chamber. and a second plasma generating means for activating the reactive gas introduced into the reaction chamber.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a reaction chamber, 2 is a substrate to be processed, and 63 installed on the electrode 12 is a gas source for generating metastable excited atoms and molecules. After that, it is converted into a metastable excited species by the first plasma generation means. In the figure, 6 represents a microwave power source, 5 represents a cavity which is a quasi-stable excited species generating section, and 5 and 6 correspond to the first plasma generating means. If the gas stored in the 3 gas source is, for example, nitrogen gas, the 5 gas is generated by the first plasma generating means.
The metastable excited nitrogen molecule N2 (A 3Σ or 6.
It has an excitation energy of 17 eV and remains in an excited state for a long time (lifetime is 2.1 seconds).

Therefore, NZ (AδΣU) generated within the metastable excitation generating section 5 (cavity) + remains in the excited state even at the stage where it moves to a position away from the generating section 5. Such a long-lived metastable excited species is introduced into the reaction chamber 1 through step 7. On the other hand, 8 is a storage section for reactive gas, and the gas valve 9. It is led to the reaction chamber 1 through a tube 10. An electrode 12 connected to an RF power source 11 is installed in the reaction chamber 1, and the reactive gas introduced as described above is decomposed or activated by the second plasma generating means consisting of 11 and 12, and the reactive gas is decomposed or activated on the electrode 12. Etching of the substrate 2 to be processed placed on the substrate 2 and formation of a film on the substrate 2 are performed.

Note that 13 is an exhaust pipe.

The reactive gas discharged from the gas storage section 8 is mainly activated by the second plasma generating means, but at the same time it is generated by the first plasma generating means and introduced into the reaction chamber 1. Since energy is also transferred from the metastable excited species, the decomposition or activation reaction of the reactive gas in the reaction chamber 1 is promoted.

If the first plasma generating means consisting of 5 and 6 in FIG. 1 is removed, the configuration becomes the existing parallel plate type plasma processing apparatus. In conventional parallel plate type processing equipment,
Although it has the advantage that the substrate to be processed can be uniformly plasma-processed, it has the disadvantage that the processing capacity is low compared to other plasma processing methods. However, by providing the above-mentioned first plasma generation means, it is possible to overcome the shortcomings in processing capacity without increasing the output of the high frequency power source 11 and therefore without increasing damage to the substrate 2 to be processed. .

As mentioned above, only a specific gas that generates long-lived metastable excited species is stored in the gas storage section 3, and the gas from the gas storage section is selectively activated by the first plasma generation means,
Since other reactive gases are directly introduced into the reaction chamber 1, the metastable excited species generated by the first plasma generation means collide with other reactive gases and become inactivated before entering the reaction chamber 1. The probability of this happening is reduced. Therefore, the inconvenience of reaction products adhering to the inner wall of the tube connecting the metastable excited species generating section 5 and the reaction chamber 1 is also alleviated. A specific example of forming a nitride film according to the embodiment shown in FIG. 1 will be described below. Nitrogen is stored in the gas storage section 3 shown in the figure, and a metastable excited species of nitrogen N2 (AδΣU) is generated by the first plasma generation means and guided to the reaction chamber 1, and a monosilane gas is stored in the reactive gas storage section 8. When the reactive gas is stored and the reactive gas is leaked to generate a high frequency discharge between the t11 poles 12, a 5iaNa film is efficiently generated on the substrate 2 to be processed.

FIG. 2 shows a second embodiment of the present invention, in which a function for irradiating light energy into one reaction chamber 1 is added to the apparatus configuration of the embodiment shown in FIG.

In the figure, 14 is a light source, 15 is a lens, 16 is a light transmitting window provided in the reaction chamber 1, and the rest of the structure is the same as that in FIG. 1. In the embodiment shown in FIG. 2, the reactive gas can be decomposed or activated using the optical idR reaction in addition to the first and second plasma generating means, so that the processing efficiency can be further improved.

As the light source 14, ultraviolet light (such as an excimer laser), carbon dioxide laser, or the like suitable for decomposing or activating a reactive gas can be used.

In the description of the above embodiments, nitrogen was cited as the gas for generating metastable excited species, but other metastable excited species such as oxygen and rare gases can be effectively used. However, in order to increase the efficiency of the plasma processing equipment.

It is desirable to use an excited species whose metastable excited state has a lifetime of 10 ms or more. Furthermore, in order to obtain uniformity of the reaction on the substrate, an excited species with a longer lifetime is required, preferably 100 m s or more. It is important to select a gas that generates such long-lived metastable excited species and to uniformly distribute the metastable excited species introduced into the reaction chamber. As such means, an annular tube is installed to surround the substrate to be processed, and the annular tube is connected to an introduction tube for metastable excited species (corresponding to 7 in FIGS. 1 and 2), and the annular tube is An effective method is to provide jet ports for the metastable excited species at approximately equal intervals in the tube.

Although monosilane has been cited as an example of the reactive gas, any desired gas can be used depending on the usage pattern of the plasma processing apparatus. For example, when using the present invention as a means for forming a film, hydrides such as monosilane, disilane, arsine, phosphine, and diborane, organometallic compounds such as trimethylgallium and trimethylaluminum, and various metal carbonyls may be used. I can do it. Furthermore, when the present invention is used as a dry etching means, CQz, S Fe, CF41 CCI2
A halogen gas or a halogen element-containing gas such as No. 4 can be used.

In the description of the embodiment shown in FIG. 1, a specific example of forming a nitride film was described. In this case, the metastable excited species + (Nz; A"ΣU) generated by the first plasma generation means not only induces the nitride film formation reaction but also serves as an element constituting the nitride film. In this way, The metastable excited species may become a constituent element of the film, but it may also be used simply to decompose or activate the reactive gas flowing out from the gas source 8. In that case, the first plasma generating means The metastable excited species generated by this process simply serves as an energy carrier that controls energy transfer.For example, a plasma processing method that uses metastable excited species of rare gases is an example of such a method.

Note that metastable excited species such as nitrogen have high energy, so the embodiment described in the above-mentioned known example, that is, the second plasma generation is performed after all the reactive gas passes through the first plasma generation section. It is difficult to efficiently form metastable excited species using a method that introduces metastable species into a reaction chamber.

In the present invention, since only the gas that forms long-lived metastable excited species is selected and passed through the first plasma generation means, metastable excited species can be efficiently formed and the excited species can be effectively used in plasma processing. It has the advantage of being available.

〔Effect of the invention〕

According to the present invention, there are problems that radicals and decomposition products generated in the first discharge chamber (preliminary chamber) are inactivated by recombination before entering the reaction chamber, and that the first discharge chamber and the reaction chamber are This has the effect of improving problems such as the formation of a film of reaction products on the inner walls of the pipes connecting the two.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram of an apparatus according to a second embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Reaction chamber, 2... Substrate to be processed, 3, 8... Gas storage section, 5... Metastable excited species generation section, 6.11...
・flt source, 12... electrode, 13... exhaust pipe, 14
...Light source, 16...Light transmission window.

Claims (1)

[Scope of Claims] 1. A reaction chamber that accommodates a substrate to be processed, first plasma generation means for generating metastable excited species, means for guiding the metastable excited species to the reaction chamber, and the reaction chamber. A plasma processing apparatus comprising: means for introducing a reactive gas into the reaction chamber; and second plasma generation means for activating the reactive gas introduced into the reaction chamber. 2. Claim 1, characterized in that the metastable excited species has a lifetime longer than 10 ms.
The plasma processing apparatus described in Section 1. 3. The plasma processing apparatus according to claim 1, wherein at least one of a rare gas, nitrogen, and oxygen is used as the gas for generating the metastable excited species. 4. A patent characterized in that, as a means for introducing the metastable excited species into the reaction chamber, the metastable excited species is introduced from a gas outlet provided in an annular tube installed so as to surround the substrate to be processed. A plasma processing apparatus according to claim 1. 5. The plasma processing apparatus according to claim 1, further comprising a light source for advancing a photo-induced reaction of the reactive gas introduced into the reaction chamber. 6. The plasma processing apparatus according to claim 1, wherein the second plasma is formed by parallel plate discharge.