JPS6221211A - Plasma-treating device - Google Patents

Abstract

PURPOSE:To improve the step coverage when a film is formed by a method wherein at least a coil is provided outside a plasma-treating chamber by shifting the center of a magnetic field from the center of the plasma-treating chamber. CONSTITUTION:Electromagnetic coils 20A-20D are provided separately on the circumference of a chamber 2 in addition to the electromagnetic coil 1 to satisfy the electronic cyclotron resonant condition heretofore in use. To be more precise, the center 3 of the plasma treating chamber 2 is not coincided with the center 24 of the coils 20A-20D. If one of the coils 20A-20D is operated, the magnetic field is inclined in the plasma treating chamber 2. Practically, the coils are set in such a manner that a current is applied to the coils periodically and successively and that the incidence angle of the ions can be changed in the range of + or -20 deg.-45 deg. or thereabout in the vicinity of the wafer. According to this constitution, the step coverage can be improved when the films are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a plasma apparatus used for depositing and etching various thin films used in semiconductor devices, etc.
Electron cyclotron resonance: ElectronCycle
XOR using otron Regonacl) f
This relates to plasma equipment.

BACKGROUND OF THE INVENTION As semiconductor devices become smaller and more densely packed, it becomes necessary to form shallower junctions, and processes are becoming lower in temperature. For example, until now atmospheric pressure CVD (chemical vapor
ur position) and LP (Low pr
essure) From what was used at 600 to 700℃ in OVD, to 200 to 300℃ in plasma CvD.
A method of forming a film at a temperature of about °C is beginning to be used. In response to these demands, a thin film forming method using all ECR plasma is attracting attention as a method that can form films of good quality at room temperature. [
Semiconductor World (Sem1conduct)
or Wor14) 1986 +IP73 ~ Itami et al. 'Thin film production technology using ICOR technology'] Figure 4 shows this conventional 1cOR plasma device, where 1 is a magnet coil, 2 is a plasma chamber, 3 is a semiconductor substrate, and 4 is a Sample stage, 6 is shutter, 6 is plasma flow,
7 is a reaction gas introduction tube, 8 is a plasma generation gas introduction tube, 9 is an XCR ion source, 10 is a microwave, 11 is a deposition chamber, and 12 is cooling water.

Problems to be Solved by the Invention This method, as shown in Figure 4, satisfies the ECR condition at 876G for the 2.45 GHz microwave 10, so the magnet of the coil 1 forms a magnetic field in the plasma chamber. ShiE
Create CR conditions. Since the magnetic field is not uniform and becomes weaker toward both ends, electrons and ions are accelerated in the direction of the weaker magnetic field. In the case of KCR plasma, 1
It is interpreted that the film quality is improved because ions of about 0 to 20 ay are incident on the wafer 3. However, this advantage turns into a disadvantage, resulting in poor step coverage. Step coverage is increasingly required as miniaturization and density increases, so it cannot be used as is.

As explained above, the present invention aims to improve step coverage using KCR plasma, which can form a high-quality film at room temperature.

The reason for poor step coverage is that ions are incident perpendicularly to the wafer. Therefore, it is sufficient to make the ions incident at a certain angle at a certain period.

To do this, it is sufficient to change the magnetic field at regular intervals.

Since it is necessary that the magnetic field to be changed does not affect the ECR conditions, a coil is installed near the plasma extraction port to bend the magnetic field, for example. That is, at least one magnet is configured so that its center is formed outside the plasma chamber.

By doing so, the incident angle of ions incident on the wafer can be varied within a certain range, and step coverage during film formation can be improved.

Embodiment FIG. 1 shows an embodiment of the present invention. The structure is almost the same as the conventional device shown in FIG. 4, but in addition to the magnet coil 1 that satisfies the conventional EOR condition, a magnet coil 20 for changing the magnetic field is installed. However, the center of the magnetic field is offset from the center of the plasma chamber 2, and the magnet coil 2o is provided. This situation is shown in FIG.

In FIG. 2a, the center 3 of the plasma chamber 2 and the center 4 of the magnetic field coil 1 (and thus the center of the magnetic field) coincide in a conventional manner. FIG. 2 shows the plasma chamber 2 according to the method of the apparatus of this embodiment.
Divide the area around it into several parts, and form four magnet coils of 2 ohm to 20 d'ii each separately. That is, the center 3 of the plasma chamber 2 and the center 24 of each coil 20 to 20D do not coincide. By operating any one magnet (coil) in such a configuration, the magnetic field will have a gradient in the plasma chamber. This situation is shown in FIG.

FIG. 3 shows the distribution of the magnetic field near the outlet of the plasma chamber, with the distance from the center of the plasma chamber being 0 (zero). FIG. 3a shows a conventional example in which the center of the plasma chamber and the center of the magnetic field coil coincide, so the magnetic field is strong at the center of the plasma chamber. FIG. 3 shows that in the method of this embodiment, the center of the plasma chamber and the center of the magnetic field coil are shifted from each other, so the magnetic field is strong in a specific direction of the plasma chamber. The solid line and the broken line indicate the difference in which of the opposing magnet coils the current is passed through.

In actual use, the magnetic coil for changing the magnetic field will pass current in sequence periodically. The strength of this magnet coil is preferably set so that the incident angle of ions changes by about ±20 to ±45° near the wafer.

In addition, for the magnet coil configured to satisfy the IIR condition, for example, the coil 2 ohm to 2 ohm in FIG.
It is possible to use the magnet coil arrangement of the present invention as in 0D, and in this case, the outer circumferential coils are energized at the same time. By doing this, the magnetic field at the center of the plasma chamber becomes weaker and the plasma moves toward the center, increasing the effectiveness of plasma confinement.

Furthermore, although the present invention has been described using the case of deposition as an example, it is also applicable to the case of etching. In the case of etching,
By energizing only specific coils.

It is possible to create a cross-sectional shape that is tilted to the subject.

Effects of the Invention As described above, according to the present invention, since the incident angle of ions incident on the wafer is varied within a certain range, step coverage during film formation is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of an ECR plasma device according to an embodiment of the present invention, FIG. A diagram explaining the arrangement of the plasma chamber and coils,
FIGS. 3a and 3b are diagrams showing the distribution of magnetic fields in the plasma chambers of the conventional example and this embodiment, respectively, and FIG. 4 is a diagram showing the same conventional apparatus. 1...Magnetic field coil, 2...Plasma chamber, 3. River...Substrate, 20 people ~ 20D...Magnetic field coil. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 7 Coil Fig. 2 (α) ZρCZU Fig. 3 (Chive (k),)

Claims (1)

[Claims] 1. A plasma device for performing deposition or etching by extracting plasma from an electron cyclotron resonance ion source, the plasma device comprising at least one magnet coil centered outside a plasma chamber.