JPH01180981A - Ecr plasma cvd method and device thereof - Google Patents

Abstract

PURPOSE:To form a thin film having excellent denseness on a substrate by holding a plasma chamber at a positive potential to reduce the space potential between the plasma chamber and the substrate. CONSTITUTION:The substrate 11 is set on a base 12 in a film forming chamber 2, and the film forming chamber 2 and plasma chamber 1 are held at a specified low pressure by an exhaust means 15. Raw gas (gaseous nitrogen, etc.), is introduced into the plasma chamber 1 from a gas inlet 8a, and a plasma current 3 and a space potential are produced by the interaction of the magnetic field caused by a magnetic field generating means 4 and the microwave caused by a microwave generating source 5. The ions in the plasma chamber 1 are allowed to react with the raw gas (gaseous silane, etc.), introduced into the film forming chamber 2 by the negative space potential to form a thin film (silicon nitride, etc.), on the substrate 11. At this time, a power source 10 is electrically connected to the plasma chamber 1 to hold the inner wall surface 1a of the plasma chamber 1 at a positive potential. As a result, even when the gas pressure in the plasma chamber 1 is held at a low pressure to improve the decomposition efficiency of the raw gas, the negative voltage of the substrate 11 is not increased, and a dense thin film is obtained.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to an ECR plasma CVD method and apparatus for forming a thin film of good quality on a substrate. This is suitable for use when forming a film.

(b) Conventional technology The ECR plasma CVD method is attracting attention as a technology that can form a thin film of good quality on a substrate without raising the temperature of the substrate (for example, 5eitaro M
Written by Atsuo, ECRplasma CVD process
ss;Extended Abstracts of
the16th(1984International
)Conference 5solid 5tate
Devices and Materials, K
obe 1984. pp. 459-462).

FIG. 2 shows a sectional view of the main parts of a conventional ECR plasma CVD apparatus. In the figure, (A) is a plasma chamber that generates plasma, and (B) is a film forming chamber located adjacent to this plasma chamber. A magnetic field generating means (C) is installed outside the plasma chamber (A) to generate plasma within the plasma chamber.
), a microwave source (D) for introducing microwaves (2-45 GHz), and a raw material gas source (E) for introducing raw material gas (for example, nitrogen gas). It is equipped with a cooling mechanism (F) that circulates the water. In the film forming chamber (B), a substrate (G) is placed in an electrically floating state with its main surface perpendicular to the plasma flow from the plasma chamber (A).
A shutter (H) that controls the opening and closing of the application of plasma flow to
). Further, a source gas (for example, silane gas) is introduced into the film forming chamber CB from a gas supply source (I) toward the plasma flow.

In the conventional ECR plasma CVD method, low pressure (e.g. 10~
Plasma is generated in a plasma chamber (A) set at a pressure of 10 Torr), and the plasma is drawn out toward the substrate (G) by a divergent magnetic field method to form a film on the substrate. For example, when the above raw materials are used, a silicon nitride film is formed on the substrate (G). The divergent magnetic field method uses the diamagnetic effect of electrons performing cyclotron motion to form a negative potential in the direction of an electrically insulated substrate and extract ions. This negative potential determines the energy of ions incident on the substrate, and if it is around 10 to 20 e■, it will work to densify the film by a moderate ion bombardment effect, and if the energy is higher than that, the film will be compressed. It is said to have the effect of increasing stress. This negative potential becomes larger as the gas pressure is lower, and films made at low gas pressures exhibit large compressive stress and cause peeling, making them useless as passivation films. Therefore, in order to produce a film with low stress, it is necessary to increase the gas pressure. Generally, when the gas pressure is high, the decomposition of the source gas becomes insufficient and the film quality deteriorates.

For example, in the case of the silicon nitride film described above, the hydrogen content increases and the acid resistance decreases.

(c) Problems to be solved by the invention As mentioned above, when the gas pressure in the plasma chamber is set low in order to improve the resolution of the source gas, the negative voltage on the substrate tends to increase, which makes it difficult to form a dense film. There is a problem.

The present invention was made in view of this problem, and is designed to prevent the negative voltage of the substrate from increasing even if the gas pressure in the plasma chamber is set low to improve the resolution of the source gas. The aim is to provide a film with excellent density by taking measures to reduce this negative space potential.

B.) Means for Solving the Problems The ECR plasma CVD method of the present invention comprises a plasma chamber for generating plasma, and a film forming chamber containing a substrate that receives a plasma flow from the plasma chamber. In a device that utilizes a negative space potential formed between the substrate and the plasma chamber in the process of forming a film thereon, the plasma chamber is maintained at a positive potential in order to reduce the negative space potential. However, the method is characterized in that a film is formed on the substrate.

Further, the ECR plasma CVD apparatus of the present invention includes a plasma chamber that generates plasma, a film forming chamber that includes a substrate that receives a plasma flow from the plasma chamber, and a gas supply system that supplies raw material gas to the plasma chamber. and a power source applied to the plasma chamber to maintain the inner wall surface of the plasma chamber at a positive potential.

Furthermore, the ECR plasma CVD apparatus of the present invention is characterized in that the inner wall surface of the plasma chamber is configured to intersect with the inflow direction of the gas flow from the gas supply means.

(B) Effect In the method of the present invention, a positive potential is applied to the plasma chamber during the film forming process, so some of the electrons in the plasma can be taken out to the outside, so that the connection between the plasma chamber and the substrate increases. It acts to reduce the negative space potential formed between the two.

Thereby, the number of electrons accelerated towards the substrate by the diverging magnetic field is reduced, and the negative potential of the substrate in the equilibrium state is small (i.e., it does not impart excessive energy to the ions imparted to the substrate. Therefore, the gas in the plasma chamber Even if the pressure is lowered to improve the resolution of the source gas, a highly dense film can be formed on the substrate without applying excessive stress to the film.

In addition, the apparatus of the present invention is equipped with a power supply to the plasma chamber in order to maintain the inner wall surface of the plasma chamber at a positive potential, thereby making it possible to suppress the negative space potential during the film forming process. In particular, in this apparatus, the inner wall surface of the plasma chamber is configured to cross the inflow direction of the gas flow from the gas supply means, so that an insulating film is formed on the inner wall surface of the plasma chamber during the film forming process. acts to eliminate tendencies,
A positive potential can be constantly applied to the inner wall surface.

(f) Example Each embodiment of the method and apparatus of the present invention will be described.

FIG. 1 is a schematic diagram of an apparatus in which the method of the present invention is carried out.

In FIG. 1, (1) is a plasma chamber that generates plasma, and (2) is a film forming chamber that is placed adjacent to this plasma chamber and receives the plasma flow (3) from plasma chamber (1). .

The plasma chamber (1) has a magnetic field generating means (such as a coil or a magnet) for generating a magnetic field in one direction of the plasma flow.
4), and receives microwaves (2.54 GHz) from a microwave generation source (5) through a waveguide (6). Further, this plasma chamber (1) receives raw material gas (for example, nitrogen) from a gas supply source (7) through a gas pipe (8). The cooling water from the cooling water source (9) is supplied to the magnetic field generating means (4) and the plasma chamber (1).
) to prevent abnormal heating. The power source (10) is connected to the plasma chamber (1
) to maintain the inner wall surface (1a) of this plasma chamber at a positive potential.

A base 02) supporting the substrate 01) is placed in the film forming chamber (2) in such a way that the substrate circle is electrically floating (floating), and the main surface of the substrate 01) is exposed to the plasma flow. It is installed so that it is perpendicular to the

It also includes a shutter α3) for controlling application or interruption of the plasma flow to the substrate Ql), and further includes a gas supply for supplying raw material gas (for example, silane gas) from the gas supply source circle to the plasma flow. It has a small terrace (child terrace).

05) is an exhaust means to lower the pressure in the film forming chamber (2),
The plasma chamber (1) and film forming chamber (2) are maintained at a predetermined low pressure (for example, 4×10 6 Torr). The inflow direction of the gas supplied from the gas inlet (8a) of the gas pipe (8) to the plasma chamber (1) is the inner wall surface (
1a) (perpendicularly in the embodiment) to prevent an insulating film from adhering to the inner wall surface (1a).

In order to form a film on a substrate by ECR plasma CVD using this apparatus, first, the base 0 in the film forming chamber (2) is
2) Set the board 01) on the specified position and exhaust means 0
Step 5) sets the film forming chamber (2) and plasma chamber (1) to a predetermined low pressure. Then, the plasma chamber (1) and the substrate 0
In order to form a negative space potential between The interaction between the microwave and the microwave generated by the microwave generation source (5) is utilized. This negative space potential causes the plasma chamber (
The ions in 1) are extracted to the substrate 01) side, and the extracted ions react with the source gas (silane gas in the example) provided in the film forming chamber (2) to form a silicon nitride film on the substrate 01). form.

When plasma chamber (1) is electrically isolated and power supply αO)
A silicon nitride film was prepared using a method in which the potential was kept at a positive potential, and the film formation rate, BHF etching rate, stress, and hydrogen content were measured, and the following data were obtained.

Sample plasma chamber Gas pressure Film formation rate BHF etch Compressive stress 0 Rate 9 Material potential (V) orr CA15'k) [λ
/min-,10(relative ratio"Za:,7."Kari0120
30 20 1.027; ■Gloss. 8 cut 0
220 130 8.2 3.237;
, 1.2X10 300 280 1.0 5
．． 54 +10 4xlO110353,51,1
Bow +20 4X10 100 40
0.8 1.1 Here, the flow rate ratio of silane gas and nitrogen gas is 0.5, and the microwave power is 600W.
It is. In addition, the BHF etching rate was measured using an etching solution with a ratio of hydrofluoric acid: ammonium fluoride = 1:6 and a liquid temperature of 20'C, and the compressive stress was measured using a flatness tester. Furthermore, the hydrogen content was measured by infrared absorption method.

In the conventional manufacturing method where film formation is performed with the plasma chamber in a floating state, when the plasma chamber is set to low pressure conditions, film formation is superior in terms of BHF etching speed and hydrogen content, as shown in sample 1, but due to strong compression Indicates stress. on the other hand,
According to the method of the present invention, which forms a film while keeping the plasma chamber at a positive potential, even if the plasma chamber is set to a low pressure condition as shown in Document 4 or 5, the compressive stress is 6.5 or 0.8. It is possible to produce a membrane that is small and has excellent acid resistance.

During repeated film formation on the substrate, a silicon nitride film tends to adhere to the inside of the plasma chamber, making it difficult to maintain a positive potential on the inner wall surface of the plasma chamber. Since the raw material gas from the supply means is blown in a direction crossing the inner wall surface, the above-mentioned adhesion can be prevented.

(G) Effects of the Invention In the present invention, a film is formed on the substrate while maintaining the plasma chamber at a positive potential in order to reduce the negative space potential between the plasma chamber and the substrate. Even if the plasma chamber is set to a low pressure condition to improve the resolution of the source gas, a film with low compressive stress and good acid resistance can be produced.

Furthermore, in the apparatus of the present invention, the inner wall surface of the plasma chamber is configured to intersect with the inflow direction of the gas flow from the gas supply means, so that the insulating film adheres to the inner wall surface of the plasma chamber during the film forming process. It is possible to eliminate this tendency, and it is possible to form a high-quality film while always applying a positive potential.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an apparatus in which the method of the present invention is implemented, and FIG. 2 is a sectional view of the main parts of a conventional apparatus. (1)...Plasma chamber, (2)...Deposition chamber, (7)
...Gas supply means (gas supply source), (101...Power source, (11)...Substrate.

Claims (3)

[Claims] (1) A plasma chamber that generates plasma and a film forming chamber that includes a substrate that receives a plasma flow from the plasma chamber, and in the process of forming a film on the substrate, the substrate and the plasma chamber In an ECR plasma CVD method that utilizes a negative space potential formed between a substrate and a substrate, forming a film on the substrate while maintaining the plasma chamber at a positive potential in order to reduce the negative space potential. ECR characterized by
Plasma CVD method. (2) a plasma chamber that generates plasma; a film forming chamber that includes a substrate that receives a plasma flow from the plasma chamber; a gas supply means that supplies raw material gas to the plasma chamber; An ECR plasma CVD apparatus comprising: a power source applied to the plasma chamber to maintain a wall surface at a positive potential. (3) The ECR plasma CVD apparatus according to claim (2), wherein the inner wall surface of the plasma chamber is configured to intersect with the inflow direction of the gas flow from the gas supply means. CVD equipment.