JPH01107539A - Microwave plasma processor - Google Patents

Abstract

PURPOSE:To control the direction of charged particles of electrons, ions incident to a substrate and to uniformly process the surface of the substrate by disposing a correction plate made of a ferromagnetic material in a sample stand. CONSTITUTION:A correction plate 31 made of a ferromagnetic material is so disposed in a sample stand 5 that lines of magnetic force relating to a divergent magnetic field are directed perpendicularly to the surface of a substrate 6. Accordingly, the direction of the lines of magnetic force of the divergent magnetic field formed by a magnetic coil 3 provided around a discharge chamber 2 is controlled perpendicularly to the front lace of the substrate 8 with the central position '0' and the end Q on the surface of a sample 6 by the plate 31 made of the ferromagnetic material provided in the stand 5, and plasma generated in the chamber 2 and produced in a sample chamber 1 at the gradient of the divergent magnetic field 7 is incident perpendicularly to the surface of the substrate 6 along the lines of magnetic force. Thus, since the direction of the charged particles incident to the substrate can be controlled perpendicularly thereto, substantially the whole surface of the substrate can be uniformly processed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is applicable to a plasma processing apparatus using microwaves such as so-called ECR, and is used to form a thin film on the surface of a substrate in the manufacture of semiconductor devices, etc. It is particularly effective when applied to manufacturing processes such as substrate surface etching and surface modification.

(Prior Art) This type of conventional technology has been used in many fields because it can extract a thick beam (ions, electrons, radicals, or a combination thereof) while using cold cathode discharge. FIG. 2 shows a conventional microwave plasma processing apparatus. Reference numeral 15 denotes a vacuum container, and the vacuum container 15 is composed of a sample chamber 1 and a discharge chamber 2. A predetermined gas is introduced into the discharge chamber 2 from the gas introduction system 9, and 2.4 gas is introduced from the waveguide 8 through the introduction window 16.
Introducing 5 GHz microwave. The strength of the magnetic field generated by the magnetic coil 3 provided around the discharge chamber 2 is 87.
When the magnetic field is 5 Gauss, electron cyclotron resonance (ECR) occurs in the discharge chamber 2 due to the interaction between this magnetic field and the electric field of the microwave, and high-density plasma is generated. This generated plasma then interacts with the gradient of the diverging magnetic field formed by the magnetic coil 3, and the above-mentioned sample chamber 1
The plasma is extracted into the sample chamber 1 through a plasma extraction window 12 provided near the boundary between the plasma and the discharge chamber 2. Then, this plasma is incident on the surface of the substrate 6 placed on the sample stage 5, and a predetermined surface treatment such as etching is performed.

In addition, the reference numeral 4 is an exhaust device that exhausts the inside of the sample chamber 1 to a predetermined pressure, 10 is a gas introduction system that introduces a predetermined gas into the sample chamber 1, and 11 is a cooling water outlet for cooling the discharge chamber 2. It is.

The microwave plasma processing apparatus described above has the following excellent features. In other words, since the plasma whose activity level has become extremely high due to ECR is taken out and made incident on the substrate 6 with appropriately adjusted energy using a divergent magnetic field, the plasma has high activity and limited energy. Due to the combined effect of ions and electrons incident on the substrate 6, surface treatment such as etching can be efficiently performed on the substrate surface with less damage.

Further, since the processing apparatus performs processing at a gas pressure in the range of 10 -3 to IPa, etching with good directionality is possible and is effective in forming fine patterns.

(Problems to be Solved by the Invention) However, the conventional apparatus described above is not necessarily sufficient in terms of uniformity of processing on the substrate, such as in-plane uniformity of etching shape and in-plane uniformity of etching speed.
This tendency was particularly noticeable as the area of the substrate 6 became larger.

This point will be explained with reference to FIG. That is, E
The magnetic field by the magnetic coil 3 for obtaining the CR condition is:
In addition to satisfying ECR conditions in discharge chamber 2, sample chamber 1
forming a useful diverging magnetic field within. However, when considering the magnetic field on the sample stage 5, the directions of the lines of magnetic force are not the same at the center position O and the end Q of the sample stage 5, as shown in FIG. 3(a). That is, at the center position O of the substrate 6, the arrow H in FIG.
A magnetic field is formed perpendicular to the substrate 6 as shown in 7.
On the other hand, at the end Q of the substrate 6, a magnetic field is formed that is oblique to the substrate 6, as indicated by an arrow H2 in FIG. As a result, electrons extracted from the discharge chamber 2 by the divergent magnetic field,
Ions are incident on the substrate along the formed magnetic field lines.

Figure 3 (1) shows the cross-sectional shape of the etching at this time.
)), (C). Here, reference numeral 17 is a mask material such as photoresist, and 18 is a material to be etched such as polysilicon. FIG. 3(b) shows the etched cross-sectional shape at the center position 0 of the substrate 6, which is vertical.

Further, FIG. 3(C) shows the etched cross-sectional shape at the end Q of the substrate 6, which is obliquely etched, making it unusable for practical use.

This phenomenon becomes more noticeable as the substrate area increases, and there is a problem in that the usable portion of the substrate area is limited to the central portion.

In addition, each discharge chamber 2 has only one sample stage 5, and in order to process multiple substrates at once, a magnetic coil is required to obtain the diameter of the cavity of the discharge chamber 2 and the ECR conditions. 3 had to be made larger, which led to the problem of making the device larger and more expensive.

(Object of the present invention) An object of the present invention is to provide a microwave plasma processing apparatus that can uniformly process the surface of a substrate by controlling the direction of charged particles such as electrons and ions that are incident on the substrate.

(Means for Solving the Problems) In order to achieve the above object, the present invention is configured as follows. That is, it is equipped with a plasma generation means consisting of a microwave generation means, a magnetic field generation means, and a discharge chamber, and a sample chamber in which a substrate to be processed is installed, and the microwave is introduced from the microwave generation means into the plasma generation chamber. on the other hand,
By applying a magnetic field by the magnetic field generating means, electron cyclotron resonance is caused in the discharge chamber by the interaction between the electric field and the magnetic field due to microwaves, and high-density plasma is generated, and the generated plasma is drawn out to the sample chamber by a divergent magnetic field. In a microwave plasma processing apparatus that processes the surface of a substrate placed on a sample stage provided in the sample chamber using the plasma, It is characterized by a correction plate made of ferromagnetic material placed inside the sample stage.

(Function) By configuring as described above, the correction plate made of a ferromagnetic material provided inside the sample stage 5 can adjust the direction of the lines of magnetic force of the divergent magnetic field formed by the magnetic coil 3 provided around the discharge chamber 2. 31, the center position 0 and the edge Q on the surface of the sample 6
The plasma generated in the discharge chamber 2 and taken out into the sample chamber l by the gradient of the divergent magnetic field 7 flows along the magnetic field lines to the substrate 6. .6' is incident perpendicularly to the surface.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Note that the process of generating plasma by causing electron cyclotron resonance due to the interaction between the electric field and magnetic field of microwaves is the same as in the conventional technology. The members will be explained using the same reference numerals.

FIG. 1 shows one embodiment of the present invention.

One of the features of the device configuration of this embodiment is that the plasma extracted into the sample chamber 1 due to the gradient of the divergent magnetic field is
In order to control the incidence in the same direction over the entire surface of the substrate on the sample stand 5 installed inside the sample stand 5, a correction plate 31 made of a ferromagnetic material capable of adjusting the direction of the lines of magnetic force is installed inside the sample stand 5. It is located at the point where the is placed.

The correction plate 31 serves as a pole piece, and the lines of magnetic force related to the formed divergent magnetic field are formed in the direction of the correction plate 31, so they are perpendicular to the substrate surface over a wide range, and therefore Charged particles in the plasma that are incident on the substrate along the lines of magnetic force become incident on the substrate 6 perpendicularly.

According to experiments, with conventional microwave plasma processing equipment,
The part of the entire surface of the substrate that can be etched without any problems in practice was about 50% of the central portion of the substrate, but with this configuration, the etched shape is uniform over the entire surface of the substrate. It has been found that the area that can be used for practical purposes expands to almost the entire surface.

In the above embodiment, etching was mainly explained, but
It is not limited to etching the substrate surface;
As long as plasma generated by electron cyclotron resonance is utilized, the present invention can be applied to manufacturing processes such as thin film formation on a substrate surface and surface modification in the manufacturing of semiconductor devices.

(Effects of the Invention) According to the microwave plasma processing apparatus of the present invention, since the direction of charged particles incident on the substrate can be controlled vertically, uniform processing can be performed over almost the entire surface of the substrate. can. Wear.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a microwave plasma processing apparatus showing an embodiment of the present invention, Fig. 2 is a schematic diagram of a conventional microwave plasma processing apparatus, and Fig. 3(a) is a surface diagram of a substrate to be processed. , FIGS. 3(b) and 3(c) are partial cross-sectional views showing the etched shape. DESCRIPTION OF SYMBOLS 1... Sample chamber, 2... Discharge chamber, 3... Magnetic coil, 5... Sample stage, 6... Substrate, 7, Diverging magnetic field, 8...
... Waveguide, 14... Plasma generation means, 31...
correction board. A-p: S7 B-B'

Claims (1)

[Claims] The plasma generating means includes a microwave generating means, a magnetic field generating means, and a discharge chamber, and a sample chamber in which a substrate to be processed is installed. By applying a magnetic field by the generating means, electron cyclotron resonance is caused in the discharge chamber by the interaction between the electric field and the magnetic field caused by microwaves, thereby generating high-density plasma, and the generated plasma is drawn into the sample chamber by a divergent magnetic field. In a microwave plasma processing apparatus that uses plasma to process the surface of a substrate placed on a sample stage provided in the sample chamber, the sample is A microwave plasma processing apparatus characterized in that a correction plate made of a ferromagnetic material is arranged inside the stand.