JPS62147733A - plasma processing equipment - Google Patents

Abstract

PURPOSE:To accurately anisotropically etch in a plasma processor by focusing the line of magnetic force of a Miller magnetic field through which a plasma is passed perpendicularly to a substrate near an electrode opposed to the substrate. CONSTITUTION:A high frequency voltage is applied to between an anode 11 and a cathode 15 to generate a plasma P between the anode 11 and the cathode 15. An annular magnet 19 is so mounted as to surround the anode 11, a magnet 21 is further mounted under a bottom plate 13b, and a Miller magnetic field M is formed in a chamber 13. The line H of magnetic force of the magnetic field is focused near the anode 11, and passed through the plasma P in a direction perpendicular to a substrate 23. A plurality of magnets 31 are arranged on the inner peripheral wall 13c of the chamber 13 so that poles are arranged laterally and longitudinally in a zigzag manner to form a multiplex bipole surface magnetic field for returning charged particles flown from the plasma P to the wall 13c of the chamber 13 to the plasma P. Thus, the substrate 23 can be accurately anisotropically etched.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plasma processing apparatus that processes a substrate by generating plasma in a chamber.

(Prior Art) Generally, semiconductor substrates are etched using plasma.

As the density of semiconductor integrated circuits has increased in recent years, the dimensions of patterns formed on substrates have become finer, and in order to faithfully etch these fine patterns in a short time, it is necessary to use highly accurate anisotropic etching. To do this, a high vacuum and high density plasma are required.

2. Description of the Related Art Conventionally, plasma processing apparatuses shown in FIGS. 5 and 6 are known.

In the device shown in FIG. 5, a large number of magnets 2 are attached to the outer circumferential wall of a chamber 1 to generate lines of magnetic force 3 on the inner circumferential surface of the chamber.

Then, gas is introduced from a gas introduction system (not shown), and the electrode (
(not shown) to generate plasma, and the magnetic force i3 prevents the charged particles of the plasma from reaching the inner wall of the chamber 1, thereby preventing a decrease in the ionization density of the plasma, and attaching a substrate (not shown) to the substrate. It is etched with that plasma.

As shown in FIG. 6, a cylindrical electrode 6 is
Lines of magnetic force 7 are formed to penetrate through the cylindrical electrode 6, and similarly to the above, gas is introduced from the gas introduction system 8 to generate plasma within the cylindrical electrode 6.

When the charged particles of the plasma cross the magnetic field lines 7, they perform Larmor motion along the magnetic field lines 7, and as the distance of movement increases due to this Larmor motion, the number of collisions with neutral particles increases, which increases the ionization density of the plasma. The substrate 9 is etched with this plasma.

(Problems to be Solved by the Present Invention) However, in the former case, since there is no magnetic field in areas other than the vicinity of the wall, the charged particles only move in a straight line. For this reason, the number of collisions of charged particles with neutral particles is reduced, which is insufficient in terms of obtaining a high-density plasma, and it has been impossible to obtain a plasma with a high ionization density in a high vacuum.

In the latter case, the ionization density increases due to the Larmor motion of charged particles, but the cylindrical electrode 6. and parallel electrode 10
Charged particles are lost.

Furthermore, in the degree of vacuum (1-100 Pa) where plasma processes such as etching are performed, the self-uniform path of particles is short, so charged particles moving toward substrate 9 do not reach substrate 9. It collides with other particles before it can do so. Due to this collision, the charged particles change their direction of movement and are directed towards the electrode 6.10, where they are lost.

Therefore, the increased ionization density decreases, and in the end, it is not possible to obtain a plasma with a high ionization density, making it impossible to perform highly accurate anisotropic etching in a short period of time.

The present invention provides a plasma processing apparatus that forms a mirror magnetic field in plasma to increase ionization density and prevents loss of charged particles due to electrodes, thereby enabling highly accurate anisotropic etching. The purpose is to

(Means for Solving the Problem) In order to achieve the above object, the present invention generates plasma between an anode electrode and a cathode electrode installed in a chamber, processes a substrate with this plasma, and In a plasma processing apparatus equipped with a surface magnetic field forming means for forming a multi-dipole surface magnetic field that confines plasma in a predetermined space, a mirror magnetic field forming means for forming a mirror magnetic field is provided in the chamber, and a mirror magnetic field is generated by the mirror magnetic field. The magnetic lines of force penetrate the plasma almost orthogonally to the substrate, and the penetrating lines of magnetic force are converged near the electrode facing the substrate.

(Action of the present invention) Charged particles of the plasma generated between the anode electrode and the cathode electrode are caught by the magnetic lines of force penetrating the plasma and perform Larmor motion. Due to this Larmor motion, the moving distance of the charged particles becomes longer. , the number of collisions with neutral particles increases, and the ionization density of the plasma increases.

(Effects of the present invention) The degree of vacuum in which plasma processes such as etching are performed is approximately 1 to 100 Pa, and the mean free path of particles is short, so charged particles moving toward the substrate do not reach the substrate. It collides with other particles before it can do so. This collision causes the charged particles to change their direction of motion and move toward the chamber wall, but are returned to the plasma by the multi-dipole surface magnetic field.

In addition, since we created a mirror magnetic field in which the lines of magnetic force converge near the electrode facing the substrate, charged particles that rush into the electrode will
It is pushed back by the focused part of the magnetic field lines and is not captured by the electrode.

Therefore, since the increased ionization density does not decrease, plasma with high ionization density can be obtained in a high vacuum.

Furthermore, since the lines of magnetic force of the mirror magnetic field penetrate the substrate almost perpendicularly, the electrostatic particles are incident perpendicularly to the substrate, thereby achieving highly accurate anisotropic etching. Furthermore, the plasma particles are confined by the mirror magnetic field and the multi-dipole surface magnetic field, so that the charged particles do not sputter on the chamber walls or electrodes. Therefore, since no gas is released from the chamber walls or electrodes, plasma with constant properties can be obtained with good reproducibility.

(Embodiment of the Invention) In FIG. 1, reference numeral 11 denotes an anode installed in a chamber 13, which is electrically grounded together with the chamber 1a. Reference numeral 15 denotes a cathode installed in the chamber 13, which is connected to a high-frequency power source 17. This high-frequency type [17 applies a high-frequency voltage between the anode 11 and the cathode 15 to generate plasma P between the node 11 and the cathode 15. It is designed to occur.

An annular magnet 19 is installed to surround the anode 11, and a magnet 21 is also installed under the bottom plate 13b to form a mirror magnetic field in the chamber 13.

The magnetic lines of force H of this mirror magnetic field are focused near the anode 11, penetrate the plasma P, and further penetrate the substrate 23 in a substantially orthogonal direction.

Further, a plurality of magnets 31 are arranged on the inner circumferential wall 13c of the chamber 13 so that the magnetic poles are alternated in the vertical and horizontal directions, and charge particles flying from the plasma P to the inner circumferential wall 13c of the chamber 13 are transferred to the plasma P. It forms a multi-dipole surface magnetic field that pushes back.

The magnets 19.21 are held on the top plate 13a and the bottom plate 13b by holding members (not shown).

After the inside of the chamber 13 is evacuated to a predetermined pressure or less by an exhaust system (not shown), for example, GF4 gas is introduced from a gas introduction system (not shown). And the anode 11 and cathode 151? by the high frequency power supply 17? Plasma P is generated by applying a high frequency voltage to il.

When charged particles in plasma P move in the direction of anode 11 or cathode 15 while crossing magnetic lines of force H,
Larmor interlocking is performed along the magnetic field line H. This Larmor motion increases the moving distance of charged particles, increases the number of collisions with neutral particles, and increases the ionization density of the plasma.

Further, the charged particles moving toward the anode 11 while performing Larmor motion move along the lines of magnetic force H, so they rush into the focusing part M of the mirror magnetic field, and are pushed back into the plasma P by the focusing part M. Furthermore, when charged particles leak from the magnetic lines of force H due to collisions and move toward the inner circumferential surface 13c of the chamber 13, the charged particles are pushed back into the plasma P by the multiple dipole surface magnetic field, so the ionization density of the plasma P does not decrease. .

Therefore, plasma with high ionization density can be obtained in a high vacuum, and thereby the substrate 23 can be anisotropically etched with high precision in a short time.

Figures 2 to 4 show other embodiments, and the one shown in Figure 2 has multiple magnets arranged so that the same magnetic poles are lined up in the vertical direction and the magnetic poles are alternated in the horizontal direction. 32
is arranged. The one shown in Fig. 3 has bar magnets 33 arranged so that the magnetic poles are alternated, and
(See Figure 1.2).

In the device shown in FIG. 4, a plurality of annular magnets 41 are installed between an anode 11 and a cathode 15 to form a multi-dipole surface magnetic field B. This annular magnet 42 eliminates a non-magnetic field, and allows the multiple dipole surface magnetic field B to be formed regularly. Further, the annular magnet 41 is held on the chamber inner peripheral surface 13c by a holding member (not shown).

Although the above embodiment describes an etching apparatus, it can also be used as a sputtering apparatus by replacing the substrate with a target and placing a material at a position facing the target.

It goes without saying that the present invention can also be applied to low-pressure plasma CVD equipment.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an embodiment of the plasma processing apparatus according to the present invention, Figs. 2 to 4 are cross-sectional views of plasma apparatuses of other embodiments, and Figs.:55 and i6 are schematic views of a conventional plasma processing apparatus. .゛11...Anode 13...Chamber 15...Cathode 19.2I...Magnet 23...Substrate
P...Plasma agent patent attorney Shizuka
Nobu-no-te Itotome Ichisho (self-praise) January 24, 1986

Claims (1)

[Claims] A surface magnetic field forming means is provided which generates plasma between an anode electrode and a cathode electrode installed in the chamber, processes the substrate with this plasma, and forms a multi-dipole surface magnetic field that confines the plasma in a predetermined space. In the plasma processing apparatus, a mirror magnetic field forming means for forming a mirror magnetic field is provided in the chamber, and lines of magnetic force due to the mirror magnetic field penetrate the plasma almost orthogonally to the substrate,
A plasma processing apparatus characterized in that the penetrating lines of magnetic force are focused near an electrode facing the substrate.