JPS63286579A - Formation of thin film - Google Patents

Abstract

PURPOSE:To form a thin film having superior adhesion and denseness on a substrate at a low temp. by forming a thin film on the surface of the substrate by chemical vapor growth and by radiating ion beams on the surface of the substrate during the film formation. CONSTITUTION:Microwaves are introduced into the plasma generation chamber 2 of a unit 1 from a waveguide 4 through the quartz window 5 and ions in plasma gas from an introduction pipe 6 are extracted into the film formation chamber 3 by a magnetic field from an excitation coil 10. In the chamber 3, the ions are reacted with a reactive gas introduced from an introduction pipe 11 on a substrate 21 to form a film. An ion source gas is introduced into a hot cathode filament 14 from an introduction pipe 15 and ionized with electrons emitted from the filament 14 and confined between the filament 14 and the anode 16 by a magnet 17. The ionized gas is converted into ion beams by passing through a leading-out grid 18 and the ion beams are radiated on the substrate 21. By simultaneously carrying out the above- mentioned operations, the ion beams are radiated on the substrate 21 and its vicinity simultaneously with the formation of the film on the surface of the substrate 21. Thus, a thin film having superior adhesion and denseness is formed on the substrate 21 at a low temp. and the quality of the film can be locally exchanged with ease.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a method of forming a thin film by chemical vapor deposition (hereinafter referred to as CVD).

[Conventional technology and problems] The technology of forming thin films and coating films on the surface of substrates by CVD has higher productivity than thin film formation by physical vapor deposition (PVD), and has advantages such as being able to form films on irregularly shaped objects. Although it has advantages,
There were the following problems.

(2) Generally, the temperature range in which a dense thin film with good adhesion can be formed by CVD is quite high, from 600 to 1000°C, and it has been impossible to form a film on a substrate with low heat resistance. Recently, CVD technology has been developed that uses plasma, excimer laser, etc. to excite the film instead of heat, and shifts the film formation temperature to a lower temperature. Otherwise, there is a problem that the film formation conditions that are favorable are limited, and it is difficult to control the film formation.

In conventional CVD technology, chemical reactions are controlled by changing the flow rate of the carrier gas and changing the substrate temperature, but such macroscopic control cannot precisely control the amount of gas around the substrate. . Furthermore, since the reactivity of the gas is not sufficiently high, the chemical composition of the reaction product deviates from the stoichiometric composition, making it difficult to form a desired compound thin film.

(2) In the chemical reaction control method described in (2) above, the reaction occurs almost uniformly over the entire substrate, and it is extremely difficult to locally change the chemical reaction or reaction conditions in a part of the thin film. . As a result, in order to locally change the film quality such as chemical composition, hardness, adhesion, density, crystal structure, etc., a complicated process such as masking a part of the substrate is required, which is difficult to achieve industrially. It was inefficient.

The present invention was made to solve the above-mentioned conventional problems, and it is possible to form a thin film with excellent adhesion and density on a substrate at low temperature, and to easily change the film quality locally. The purpose of this invention is to provide a method for forming thin films.

[Means for Solving the Problems] The present invention provides a thin film characterized by forming a film on the surface of a substrate by chemical vapor deposition (CVD) and simultaneously irradiating the surface or the vicinity of the substrate with an ion beam. This is the formation method.

Examples of the substrate include semiconductor wafers, tools made of steel, and the like.

Examples of the material of the film formed by the above-mentioned CVD include nitrides such as silicon nitride, aluminum nitride, and titanium nitride, and oxides such as alumina, zirconia, and silica.

The ions in the ion beam include, for example, argon,
Examples include nitrogen, oxygen, and radicalized hydrocarbons.

[Operations] According to the present invention, chemical vapor deposition (CVD) is applied to the surface of the substrate.
By irradiating the surface of the substrate or the vicinity of the surface with an ion beam at the same time as forming a film, the release of adsorbed atoms, the minute displacement of atoms, and the introduction of defects as a result occur repeatedly on the substrate and the surface of the film being formed. . As a result, the surface is cleaned and the microstructure within the film becomes finer due to an increase in the number of condensation nucleation sites, making it possible to form a dense thin film with excellent adhesion to the substrate.

Moreover, it becomes possible to lower the film-forming temperature, and it is possible to form a film even on a substrate with poor heat resistance.

In addition, even when it is difficult to form a compound thin film with a stoichiometric composition using conventional methods, by irradiating with a highly reactive ion beam, the missing elements can be reacted as one of the film components as an auxiliary. Therefore, a compound thin film having a desired composition can be formed.

Furthermore, by locally irradiating a highly reactive ion beam, it is possible to form a thin film on a desired portion of the substrate with excellent density and adhesion as described above and having a desired chemical composition. At this time, by moving the ion source or the substrate, it is possible to efficiently and locally change the film quality without performing complicated operations such as masking.

Note that the atmosphere in which film formation is performed using normal CVD technology is under normal pressure or reduced pressure of 10' torr to 102 torr, and at this degree of vacuum, particles in the ion beam frequently collide with atoms and molecules of the claw body. This is repeated and the kinetic energy, charge energy, etc. are lost, making it difficult to obtain the above-mentioned effects. For this reason, in the past, almost no attempt was made to combine CVD and an ion beam. However, in recent years, CVD techniques under relatively high vacuum up to 10' torr, such as electron cyclotron resonance (ECR) plasma CVD, have been put into practical use. The present invention focuses on the fact that ion beams can exhibit the effects of high-energy particles under such high vacuum conditions, and by applying this to CVD, it is possible to achieve the aforementioned improvement in film quality and controllability of chemical composition. It is something that

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The drawing is a schematic cross-sectional view showing an ECR plasma CVD apparatus equipped with a Kauffman type ion source used for forming the thin film of this example. Reference numeral 1 in the figure is a chamber, and a plasma generation chamber 2 is formed at the upper side of the chamber 1, and a film forming chamber 3 is formed below it. The plasma generation chamber 2
A rectangular microwave waveguide 4 is connected to the upper center of the chamber 1 corresponding to the chamber 1, and a quartz window 5 is arranged in the portion of the chamber 1 to which the waveguide 4 is connected.

A plasma gas introduction pipe 6 is connected to the upper part of the chamber 1 corresponding to the plasma generation chamber 2. The side wall of the chamber 1 corresponding to the plasma generation chamber 2 has a double wall structure, and a cooling water supply pipe 8 and a discharge pipe 9 are connected to an annular space 7 formed by the two walls. It is possible to suppress the temperature of the plasma generation chamber 2 from rising.

An excitation coil IO is arranged around the side wall of the chamber 1 corresponding to the plasma generation chamber 2.

A reaction gas introduction pipe 11 is connected to a side wall of the chamber 1 corresponding to the film forming chamber 3 . A flange 12 is formed on the side wall of the chamber 1 corresponding to the film forming chamber 3, and an ion source housing 13 is attached to this flange 12. A hot cathode filament 14 is disposed inside the ion source housing 12, and an ionized gas introduction tube 15 inserted from outside the housing 13 is connected to the filament 14. An annular anode 16 and a magnet 17 are arranged approximately concentrically around the outer periphery of the filament 14. Further, a drawer grid 18 is formed in a portion of the casing 14 located on the film forming chamber 3 side of the chamber 1.

Furthermore, a substrate holder 19 is arranged within the film forming chamber 3. Note that an exhaust pipe 20 connected to a vacuum pump (not shown) is provided at the bottom of the chamber 1.

In the above-mentioned ECR plasma CVD apparatus, CVD is performed using a microwave that passes through a microwave waveguide 4 and is guided into the plasma generation chamber 2 of the chamber 1 through a quartz window 5, and an electron cyclotron that is maintained by a magnetic field applied by an excitation coil IO. Ions in the plasma generated under the resonance condition are drawn out into the film forming chamber 3 by a magnetic field, and the reaction gas introduction pipe 11
This is done by causing a reaction gas introduced from the substrate to react on the substrate 21 held in advance by the substrate holder 19. on the other hand,
The ion source is operated by introducing gas into the hot cathode filament 14 from the ionized gas introduction tube 15, and the gas is emitted from the filament 14 and is ionized by electrons trapped between it and the anode 1B by the magnet 17. The beam passes through the beam, forms a beam, and irradiates the substrate holder 19 held by the substrate holder 19. By performing these operations simultaneously, the ion beam is irradiated onto the substrate 21 and its vicinity while a film is being formed on the surface of the substrate 21.

A silicon nitride thin film was formed using the ECR plasma CVD apparatus described above under the following conditions. That is, the diameter is 7.6o
Using a silicon wafer as the substrate 21, N2 gas was introduced into the plasma generation chamber 2 and 5IH4 gas was introduced into the film forming chamber 3 so that the flow rate ratio was N2/SI H4-1,0. Pressure inside chamber 1 is 5 x 10'5
While performing open film formation for 30 minutes with the temperature of the torrs substrate 21 set at 100°C, an argon ion beam with a diameter of about 5G was applied at an acceleration voltage of 300V and a beam current density of 0.
1 mA/cIj, ■Nitrogen ion beam with a diameter of approximately 5 cIn was accelerated at a voltage of 500 V and a beam current density of 0.4 fflA/
Each substrate 21 was irradiated with cI11 toward the center.

Therefore, the Si/N composition ratio was determined at two locations on the substrate after film formation: near the center of the substrate that was irradiated with the ion beam, and at a location 3c11 away from the center of the substrate that was not thought to be irradiated with the ion beam. The refractive index and the AE generation (peeling initiation) load were measured by a scratch test. The results are shown in the table below.

As is clear from the table above, regarding the substrate irradiated with the argon ion beam, although the Si/N composition ratio is the same at the two test positions, the center of the substrate irradiated with the same ion beam It can be seen that the silicon nitride thin film has improved density and adhesion in this region, showing a higher refractive index and SE generation load.

In addition, in the substrate irradiated with the nitrogen ion beam, a composition ratio of 0.75 corresponding to stable nitride (Si3N4) was obtained at the center of the substrate, indicating that nitrogen that contributes to chemical reactions is added by the ion beam. .

The above-mentioned embodiments demonstrate the effectiveness of ion beam irradiation in the CVD method in that thin films with clearly different film qualities can be formed on the same substrate.

[Effects of the Invention] As detailed above, according to the present invention, a thin film with excellent adhesion and density can be formed on a substrate at low temperatures, and the film quality can be easily changed locally. A forming method can be provided.

[Brief explanation of the drawing]

The drawing shows the ECR plasma CV used in the embodiment of the present invention.
It is a schematic sectional view showing D device. 1...Chamber, 2...Plasma generation chamber, 3...
Film forming chamber, 4... Microwave waveguide, 6... Plasma gas introduction tube, 1O... Excitation coil, 11... Reaction gas introduction tube, 14... Hot cathode filament, IB...
Annular anode, 19... substrate holder, 20... exhaust pipe,
21... Board.

Claims (1)

[Claims] 1. A method for forming a thin film, which comprises forming a film on the surface of a substrate by chemical vapor deposition and simultaneously irradiating the surface or the vicinity of the substrate with an ion beam.