JPS5963699A - Film forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention provides a plasma generation chamber in which a gas is introduced and plasma is generated using electron cyclotrosi resonance using a magnetic field and microwaves, and a sample chamber in which a film forming raw material gas is introduced and a sample is placed. □Specifically for plasma extraction This relates to a film forming apparatus in which a cylinder is provided on the sample chamber side.

It has a plasma generation chamber and a sample chamber that generate plasma using electron cyclotron resonance using a magnetic field and microwaves, and a plasma extraction port is installed in the partition wall between the plasma generation chamber and the sample chamber to draw plasma onto the sample using a magnetic field gradient. An example of the configuration of a conventional film forming apparatus for forming a film on a sample is shown in FIG. Here, / is a plasma generation chamber, 2
3 is the sample chamber, 3 is the introduction pipe for introducing the film forming raw material gas into the sample chamber λ, G is the connection to the exhaust system, S is the sample stage, O is the sample on the sample stage S, 7 is the plasma generation chamber l is a magnetic coil for generating a magnetic field, r is, for example, 2-IIA
; A waveguide for introducing the GHz microwave 9 into the plasma generation chamber/; /θ is a gas introduction pipe for introducing gas into the plasma generation chamber/; l/ is a cooling tube for the plasma generation chamber l; A cooling water inlet pipe /2 is a discharge pipe for the cooling water, and 13 is an insulating material plate, such as a quartz plate, for introducing microwaves into the plasma generation chamber.

In such an apparatus, since plasma is generated in the plasma generation chamber using electron cyclotron resonance using microwaves and a magnetic field, highly active plasma can be generated at a gas pressure of 10-' Torr.

Therefore, for example, in the formation of SiO2 with SiH4 and 02 or the formation of Si -C with SiH4 and OH4,
Can form a delicate film at low temperatures.

On the other hand, in the case of such a conventional device configuration, the film forming raw material introduced into the sample chamber λ from the introduction tube 3 easily flows into the plasma generation chamber/inside the plasma generation chamber 1. A film of approximately the same amount as that on sample 6 ends up being formed. especially,
When forming a film of conductive material, the conductive material adheres to a quartz plate (hereinafter referred to as microwave introduction window) that maintains a vacuum and serves as a microwave introduction port and enters the plasma generation chamber/inside. Not only does this prevent the introduction of microwaves, but the conductive film attached to the quartz plate/3 of the introduction window causes loss of microwaves and generates heat in this area.
It has a drawback that it is difficult to form a film as thick as 0.3 m.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a film forming apparatus that can solve the above-mentioned drawbacks and form a high-quality, dense, thick film on a low-temperature substrate without heating the substrate.

In order to achieve such an object, the present invention provides a plasma generation chamber into which a gas is introduced and generates plasma using electron cyclotron resonance using a magnetic field and microwaves, and a sample chamber into which a film forming raw material gas is introduced and a sample is placed. In a film forming apparatus that has a plasma extraction port in the partition wall between the plasma generation chamber and the sample chamber, and forms a film on the sample by drawing the plasma onto the specimen using a magnetic field gradient, the plasma extraction port is located on the sample chamber side. A plasma extraction tube is provided that extends toward the

The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic diagram showing the tube portion of the plasma extraction reservoir in the film forming apparatus of the present invention. Here, I is a cylinder extending toward the sample chamber/I side of the plasma extraction port. This plasma extraction tube/4t can be made of either a conductive material or an insulator, and its shape is as follows:
Although a structure along the lines of magnetic force may be used, in order to simplify the explanation, an example will be described in which the shape of the barrel is cylindrical. The remaining parts of the device of this example are the same as the device shown in the first figure, and will be omitted here.

The operation of the device of this example will be explained below.

Made of membrane formation in this example! n, the operating pressure in the sample chamber λ is /θ
Torr scale, and the mean free path of the molecules in the sample chamber λ is number/θ. Instead, the molecules of the raw material gas for film formation mainly collide with the side wall of the sample chamber 2, thereby changing the direction of travel and flowing into the plasma generation chamber 1. Compared to the conventional structure shown in the first drawing without a cylinder, when the cylinder /F is provided, the penetration angle that allows the plasma generation chamber to enter the plasma generation chamber /F decreases according to the diameter and length of the cylinder /F. Furthermore, in the plasma surrounding atmosphere in which film formation is performed, when the film forming raw material gas collides with the wall, the probability that it will adhere to the wall has a certain value. Therefore, the amount of molecules of the film-forming raw material gas that collide with the inner wall of the cylinder several times and enter into the plasma generation chamber 1 rapidly decreases depending on the number of collisions. Therefore, by providing the cylinder /4', it is possible to significantly prevent the film forming raw material gas introduced into the sample chamber λ from flowing back into the plasma generation chamber l.

Note that this effect will be further enhanced if the cylinder/p is cooled with liquid nitrogen or the like. The possibility that the constituent substances of cylinder/+ will be mixed into the film formed on sample B is extremely small, considering that the film tends to adhere to this cylinder. If a cylinder-constituting substance is found as an impurity in the film, if the cylinder is formed of the same material as the intended film, the contamination of the impurity can be prevented. Alternatively, only the surface of the cylinder or the surface in contact with the plasma flow may be coated with the same material as the intended film to be formed.

With the above configuration, SiH4 gas is introduced from the introduction tube 3 into the sample chamber /θs a a bx, and Ar 70500M is introduced into the plasma generation chamber 1 from the introduction tube IO to form a film. Comparing the Si film formed on B, it was found that the amount of adhesion on the microwave window was small, and the amount of adhesion on the cylinder/
4! We were able to confirm the effect of

Next, a second embodiment of the present invention is shown in FIG. In this example,
The plasma extraction cylinder 13 is made of a conductive material, such as stainless steel, and an insulator ring, such as a ceramic ring or a quartz ring /3, is interposed between the sample chamber λ and the cylinder /f, and this cylinder /4' is connected to the sample chamber - installed so that it protrudes from the
A voltage can be applied between the sample chamber ko and the cylinder /f through a wiring 16. Further, /7 and /za are switches, which are switched depending on whether a positive or negative voltage is to be applied to the sample chamber or when the sample chamber is electrically suspended. /9 is a variable resistor connected in parallel with the DC power supply, which adjusts the voltage applied to the cylinder tj and takes it out through wiring /6. Note that a constant voltage power supply or the like may be used in place of the portions 17 to 17, and its output voltage may be applied to the cylinder /'l through the wiring /6, thereby controlling the voltage of the cylinder la.

Figure q is from the center of the plasma outlet to the sample chamber λ side //
When an electrode (hereinafter referred to as a probe) of /long φ x 30 electrodes (hereinafter referred to as a probe) is placed at the position of CIn, the measurement results of the relationship between the voltage applied between the sample chamber λ and the probe and the semen flowing through the probe are shown. show. Generally, when a negative potential is applied to the probe and the change in current due to flowing ions with respect to the potential is measured, the probe current approaches a constant value. The current at this time is called a saturation current, and this saturation current is a measure of ion density. In this measurement, in the configuration shown in FIG. 3, the diameter of the plasma extraction cylinder/F was set to 3 cm (graph A) and 7 cm (graph B) in length a1. The surface diameter of the plasma generation chamber l is -, and Ar is 10500 from the introduction pipe /θ.
M flow, the degree of vacuum in the sample chamber λ was set to 2×/θ-4 Torr, and the microwave power was set to '20. I put in OW.

Now open the switches /7 and 1g and open the cylinder /(
+' is electrically suspended from the sample chamber 2, and when the length of the cylinder 14I is 3 cm and 7"an, the current in both cases is 7 cm (the current in case D' is slightly smaller, but both There is almost no difference between the two.''This means that
Compared to a cylinder/F with a length of 3cm, the length of the cylinder/4t can be made 7cm without affecting the ion density in the plasma, and therefore the plasma generation chamber l of the film forming raw material gas can be reduced. This shows that it is possible to reduce the inflow into the interior.

In Figure S, under the conditions shown in Figure ψ, the length of the cylinder is set to 7 degrees, and the voltage applied to the cylinder/I and the probe voltage are set to 0 (graph C) and -〃v (graph D). Shows the relationship between the current and current flowing when

The measurement results show that the ion density in the plasma flow can be controlled to some extent by the voltage applied to the cylinder/4'. -Figure 6 shows length 7cm
I) Shows the relationship between the film formation time and the film thickness when a cylinder is attached (graph E) and when it is not attached (graph F). For this measurement, the introduction tube l into the plasma generation chamber l.
From θ, Ar and H2 are 70800M and 1, respectively.
00500M was introduced, and the partial pressure of NbF 5 in the sample chamber λ was set to be jX/θ−2Pa. At this time, the microwave power was set to 300W. When a cylindrical portion is provided, the thickness of the formed film increases depending on the forming time. On the other hand, when there is no cylinder, a conductive film adheres to the microwave introduction window 13, which increases the horizontal loss of microwaves, reduces the effective microwave power entering the plasma generation chamber l, and increases the thickness of the formed film over time. will hardly increase. In addition, there is a risk that the conductive deposited film will be heated due to microwave loss in the microwave introduction window 13 and the quartz plate of the window material will break.
It was difficult to form a film over a long period of time (more than 1 minute).

As mentioned above, the cylinder/(
/ has the effect of significantly preventing the backflow of the film-forming raw material gas introduced into the sample chamber λ to the plasma generation chamber /, and furthermore,
It does not have any adverse effect on plasma extraction. Therefore, a thick film of conductive material such as metal can be easily formed.

As described above, according to the present invention, it is possible to reduce the backflow of the gas introduced into the sample chamber into the plasma generation chamber, so there is an advantage that film formation in the plasma generation chamber can be suppressed. Therefore, it is possible to reduce the occurrence of defects in the film formed on the sample due to peeling of the film attached to the plasma generation chamber, and also to form a thick film of a conductive substance such as metal. Additionally, according to the present invention, the amount of ions in the plasma flow can be controlled by applying a voltage between the sample chamber and the cylinder provided at the plasma extraction port.

[Brief Description of the Drawings] Fig. 1 is a diagram showing the schematic configuration of a conventional film forming apparatus;
The figure is a schematic diagram showing an example of the structure of the tube for drawing out plasma in the film forming apparatus of the present invention, and FIG. A schematic diagram showing the cylinder part in another example of the invention, Fig. 1 is a graph showing the relationship between the voltage applied to the probe inserted into the plasma flow and the current flowing through the probe, and Fig. S shows the voltage applied to the cylinder FIG. 6 is a graph showing the relationship between the current flowing through the probe and the current flowing through the probe, and FIG. 6 is a graph showing the relationship between the film formation time and the formed film thickness, showing the effects of the present invention. /... Plasma generation chamber, λ... Sample chamber, 3... Film forming raw material gas inlet, D... Connection to exhaust system, S... Sample stand, 6... Sample stand Sample on j, 7... Magnetic coil for generating a magnetic field in the plasma generation chamber, l... Microwave waveguide, 9... λ, LtGHz microwave, lθ... gas inlet, l/... Cooling water introduction pipe for cooling the plasma generation chamber, 12.
...Cooling water discharge pipe, 13...Microwave introduction window, lg...tube, 15...Insulator, 16...Wiring for applying voltage to the tube, 17...switch, 7g... ...Switch, 19...Variable resistor, 〃...DC power supply. Patent Applicant: Nippon Telegraph and Telephone Public Corporation Figure 1 Figure 5 Cylindrical portion of electric wire (V) Figure 6 0 5 10 15
20 meters (minutes)

Claims (1)

[Claims] 1) A plasma generation chamber into which a gas is introduced and generates plasma using electron cyclotron resonance using a magnetic field and microwaves, and a sample chamber into which a film forming raw material gas is introduced and a sample is placed; In a film forming apparatus, a plasma extraction port is provided in a partition wall between the plasma generation chamber and the company materials room, and a film is formed on the sample by drawing plasma onto the sample using a magnetic field gradient. A film forming apparatus characterized by being provided with a plasma drawing tube extending toward the sample chamber side. 2. In the film forming apparatus according to claim 1,
The cylinder is made of a conductive material, and the cylinder is arranged in the main body of the film forming apparatus via an insulator, so that a voltage can be applied between the main body of the apparatus and the cylinder. Film forming equipment. 5) In the film forming apparatus according to claim 1,
A film forming apparatus characterized in that a surface of the tube in contact with the plasma flow is made of the same material as a film to be formed on the sample. 4) In the film forming apparatus according to claim 1,
A film forming apparatus characterized in that the cylinder is made of an insulator.