JPS5915982B2 - Electric discharge chemical reaction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for performing queching in which a thin film is created by causing a chemical reaction by electric discharge in a vacuum.

Recently, a thin film was made using a chemical reaction in a vacuum.
Systems that perform etching have become popular.

For example, plasma chemical vapor deposition (plasma CVD),
Some examples include reactive sputter etching using bipolar discharge (vacuum OVD) and plasma etching.
However, since all of these methods use bipolar or electrodeless discharge, reactions can only be carried out at relatively high pressures, such as about 1 Torr. Also, since the plasma density was not that high5, the reaction rate was not that high. An object of the present invention is to provide a novel apparatus that can form and etch thin films by causing high-speed chemical reactions at low pressure and low temperature.

Another object of the invention is to provide an apparatus capable of producing thin films of relatively high purity.

The present invention is a discharge chemical reaction device that generates a chemical reaction by discharge to form a thin film on the surface of a substrate, or performs etching. It consists of a means for controlling the pressure of the electrode, a means for causing an electric discharge around the electrode, and a means for feeding a reactive gas that is easily decomposed by the electric discharge into the vicinity of the electrode. Next, this invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of the invention. However, for the sake of clarity, the central cylindrical electrode 10 is partially shown in cross section. In the figure, reference numeral 510 denotes a cylindrical electrode for setting an electric field, and an opening 21 is provided on the surface of the electrode to send a reactive gas into the discharge space. 13 is a cylindrical magnet for setting a magnetic field perpendicular to the electric field, and 14 and 15 have a '0' structure so that the surface of the electrode can be well cooled or heated at the inlet and outlet of the forced coolant.

Reference numeral 16 indicates lines of magnetic force generated by the magnet 13, and reference numeral 17 indicates a coil for setting a magnetic field from the outside when an internal magnet cannot be provided.

Depending on the case, both may be set at the same time, or an alternating current may be applied to the coil to set an alternating magnetic field j5. 21 is a reaction gas outlet, 22 is a pipe for feeding the reaction gas, 2
3 is a variable leak, and 24 is a cylinder for storing gas.

Reference numeral 31 denotes substrates arranged in a cylindrical shape in a vacuum chamber, and although a mechanism for holding the substrates 31 is not shown, a method used in ordinary vacuum equipment is used.

41 and 42 are flanges, 43 is an insulator, 44 is an exhaust port,
45 is a stainless steel vacuum chamber.

The pressure inside the tube can be freely adjusted depending on the exhaust speed of the gas exhausted from the exhaust port 44 and the inflow amount of the reaction gas. 51
52 is a switch, and 52 is a power source, both AC and DC are used.

When a voltage is applied between the electrode 10 and the stainless steel vacuum chamber, an electric field orthogonal to the magnetic field is generated on the surface of the electrode 10. The operation of this device is to evacuation to a predetermined vacuum level through the exhaust port 44, and then introduce a predetermined reaction gas through the piping 22 to set the inside of the vacuum chamber to a predetermined pressure.

When the switch 51 is then closed, a discharge occurs within the device. At this time, the electrons emitted from the surface of the cylindrical electrode 10, especially near the magnetic lines of force 16, move toward the substrate 3 due to the electric field existing near the surface.
is accelerated in the direction of However, the flight direction is bent by the magnetic lines of force 16 (mainly acting on the orthogonal components) which are perpendicular to this electric field, and the object is trapped within the magnetic field. In this way, a so-called magnetron discharge is formed, generating a high-density plasma and maintaining the discharge to an extremely low pressure of less than 10-5 T0rr (this value can be further reduced by the selection of the magnetic and electric fields). This electric discharge activates the compound vapor existing in the space and promotes a chemical reaction, causing the substrate 31 to
A thin film can be grown on top of the . For example, if monosilane SiH4 is introduced as a reaction gas, a silicon film can be produced, and if monosilane SiH4 and ammonia NH4 are introduced simultaneously, a silicon nitride film can be produced. This reaction occurs in the plasma generated by the discharge, such as SiH4 and N
It is thought that H4 was decomposed and silicon or a silicon nitride film was formed. In this example, since an orthogonal electromagnetic field is used, the discharge can be maintained up to about 10-5T0rr, and compared to the conventional method, which was at most 10-2T0rr, the discharge is performed at a pressure that is about 1/1000th of that of the conventional method. I was able to do that. Therefore, it was possible to significantly reduce the amount of gas in the thin film formed on the substrate and create a thin film with high dullness. It was found that improving the dullness is extremely effective for film formation (it was found that it prevents the generation of harmful fine powder during film formation). In addition, the charged body flowing into the substrate is bent by the magnetic field and flows into other parts, such as the flange 42 and the inner surface of the vacuum chamber, and the resistance or energy, which has become extremely small, is significantly reduced, so the temperature rise is extremely low. small. On the other hand, the thin film production rate was significantly higher than that achieved by conventional methods, as a result of realizing high-density plasma using orthogonal electromagnetic fields. In the case of etching, it was found that pressure reduction increases the straightness of particles to advance into the substrate and significantly reduces side etching (or undercut), and is found to be extremely effective for microfabrication. It was also found that plasma can be confined only to the areas where it is needed, even under high pressure conditions. Next, we will discuss some precautions when creating these devices. In the above embodiment, the case where a thin film was formed was described, but when etching the substrate 31 itself or the thin film formed on it and removing a part of it, a reactive gas such as fluorochlorocarbon, for example, is used by discharge. Materials that are chemically active and generate upon discharge a component that reacts with the object to be etched to form a compound having a high vapor pressure are desirable. Further, it is desirable that an electric field exists on the surface of the substrate itself. As an example of this, it may be desirable to electrically insulate the substrate from other structures and apply a voltage thereto. Furthermore, it is often better to place the outlet for the reactive gas very close to the substrate. Further, the electrode 10 may be removed in such a case, or the substrate may be grounded and a positive voltage applied to the electrode. As for the magnetic field, only the external coil 17 may be used, the internal magnet 13 may be used, or these may be used in combination. In the case of forming a thin film, the rate of film formation may be further increased by adding film formation by sputtering to cover the electrode surface with the same material as the thin film to be formed. Conversely, it has been found that placing a substrate on the electrode surface can increase the etching rate in the case of etching, similar to the aforementioned case of electrically insulating the substrate from other structures and applying a voltage thereto. Overall, in order to carry out the chemical reaction uniformly, the positions of the reaction gas outlet and exhaust port are important, and special care must be taken as to where they are installed.

Regarding the exhaust port, for example, if it is necessary to exhaust air from the center of the system, an exhaust port may be attached to the top of the vacuum chamber,
They may be distributed and provided in various locations. The substrate may also be heated (if necessary). Figure 2 is the second example of this invention.
FIG. 3 is a plan view taken from the line 3-3 in FIG. 2 in the direction of the arrow.

In the figure, 18 is a pole piece, 32 is a substrate holder, and other symbols are the same as in FIG. In this embodiment, a chemical reaction is caused by generating an orthogonal electromagnetic field on a circular plate, and can be understood in substantially the same way as the embodiment shown in FIG. In this embodiment, the electrons make a linear motion along a continuous trajectory in the direction of arrow 19, creating a high-density plasma. Fig. 4 shows a third embodiment, which is different from Fig. 3, in which a discharge chemical reaction is caused by providing an orthogonal electromagnetic field on a rectangular flat plate. Since the length can be increased depending on the force width in the longitudinal direction, it is suitable for continuous processing by continuously feeding substrates in the direction of arrow 1, for example.

Needless to say, the above does not have any limiting meaning, and many modifications are possible. For example, a Penning discharge electrode, an inverted magnetron electrode, etc. are other examples in which the electric field and the magnetic field are orthogonal, and in addition to these, already known electrodes in which the electric field and the magnetic field are orthogonal can be used in many cases. As described in detail above, according to the present invention, it is possible to obtain an apparatus capable of forming or etching a thin film with a high degree of inertness at high speed by utilizing a chemical reaction at low temperature and low pressure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of the present invention, FIG. 2 is a sectional view of a second embodiment, FIG. 3 is a plan view taken from line 3-3 in FIG. 2, and FIG. is a plan view of the third embodiment (corresponding to FIG. 3 of the second embodiment), 10, 49... Electrode, 13... Magnet, 16...・Magnetic field lines,
17... Coil, 18... Pole piece, 21... Opening, 22... Reaction gas introduction piping, 23... Variable leak, 24・
...Gas cylinder, 31...Substrate, 32.
... Board holding stand, 44 ... Exhaust port, 45
...Stainless steel vacuum chamber, 52...Power supply.

Claims (1)

[Claims] 1 a vacuum container, an electrode placed inside the vacuum container,
magnetic means disposed adjacent to the electrode for producing lines of magnetic field which exit from one point of intersection on the surface of the electrode, curve and enter another point of intersection on the surface; means for causing a discharge near the generating electrode;
It has a means for sending a vapor of a compound that is easily decomposed by electric discharge into the vicinity of the electrode, and a means for adjusting the pressure around the electrode, and a reaction occurs between the fed compound itself or the compound vapor and the substrate. A discharge chemical reaction device characterized by: