JPH03215673A - Microwave plasma treating device - Google Patents

Abstract

PURPOSE:To widely form plasma and to uniformize the current density thereof so as to uniformly treat a substrate by forming the aperture area of the window for introducing microwaves into a plasma forming chamber larger than the area of the substrate to be treated. CONSTITUTION:The microwaves 8 generated by a microwave power source 6 are introduced through a waveguide 5 and the introducing window 4 into the plasma forming chamber 1. This plasma forming chamber 1 is constituted under the conditions of a microwave cavity resonator. Electron cycltron resonance 9 is induced by the electric field generated by the microwaves 8 and the magnetic field of an air-core solenoid coil 3 orthogonally therewith. The treating gas introduced from an introducing port 7 is converted to the plasma by this phenomenon. The substrate 12 impressed with a high-frequency bias voltage via a substrate holder 10 connected to a power source 11 is irradiated with this plasma, by which the substrate is treated. The aperture area of the above-mentioned introducing window 4 is made larger than the area of the substrate 12. The spread of the plasma is increased in this way and the current density thereof is highly uniformized. The entire surface of the substrate 12 is thus irradiated uniformly with the plasma of a high density and is thereby uniformly treated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention uses plasma generated using the electron cyclotron resonance phenomenon to perform processing such as etching the surface of a substrate and forming a thin film on the surface of the substrate. The present invention relates to microwave plasma processing equipment used in semiconductor device manufacturing processes and the like.

(Prior art) As a conventional device of this kind, for example, Japanese Patent Application Laid-Open No. 5Ei-
The invention disclosed in Publication No. 155535 is known.

As is clear from FIG. 2, the microwave plasma processing apparatus disclosed in this publication introduces a processing gas from a gas introduction system 7 into a plasma generation chamber 1 configured as a cavity resonator, and also uses microwave Microwaves generated by a power source 6 are introduced via a waveguide 5 and an introduction window 4 to cause an electron cyclotron resonance phenomenon 9 in the plasma generation chamber, and the processing gas is turned into plasma using the energy. Then, the plasma is extracted from the plasma extraction window 13 into the substrate processing chamber 2 by a divergent magnetic field, and the surface of the substrate 12 placed on the substrate holder 10 is subjected to a predetermined process (for example, etching) by the ion bombardment effect of the plasma flow 19. ).

In addition, there is also a method in which the substrate 12 is placed inside the plasma generation chamber 1 for processing.

In conventional devices of this kind, the opening diameter of the microwave introduction window 4 is generally quite small. For example, the diameter of the plasma generation chamber 1 is 170 mm, and the diameter of the substrate 12 is 8'''.
(Standard dimension is 200 mm) 100m for φ
Those with an opening diameter of about mφ or less are used.

(Problems to be Solved by the Invention) However, in the conventional apparatus described above, the distribution of the ion current density within the plasma generation chamber 1 is extremely poor, and the average value ±
35% or more, and once this plasma is transferred to the plasma generation chamber 1 using a divergent magnetic field as in the apparatus shown in Figure 2.
The substrate 12 is pulled out into the processing chamber 2 adjacent to the processing chamber 2.
However, the ion current density distribution on the substrate surface can only be improved to about ±20% of the average value.

In addition, when drawing out plasma, a number of drawbacks appear due to its operation. One of them is that the plasma flow 19 spreads due to the divergent magnetic field, so that ions are incident obliquely to the substrate surface at the outer periphery of the substrate 12. Therefore, the processing status of the surface of the substrate 12, for example, in the case of etching, When observing the etching shape, it is found that Fig. 3a (center part of the substrate)
, b (middle part) and C (peripheral part) show the etching mask 14, etching pattern and cross-sectional shape of the substrate material 12 after the etching process. In part C, the etching shape is quite oblique.

Furthermore, since the ions are extracted over a long distance, ions are scattered along the way, resulting in severe side etching, and the ion current density also naturally decreases.

(Differences between the invention and the prior art) In contrast to the conventional microwave plasma processing apparatus described above, the processing apparatus of the present invention has high ion current density, uniform processing, uniform anisotropic etching when the processing is etching, The difference is that this is realized for large-diameter wafers.

(Means for solving the problems) The present invention is configured as follows. That is, it is configured such that microwaves are introduced into the plasma generation chamber through a microwave introduction window having an opening diameter larger than the diameter of the wafer to be processed. The wafer being processed is
There are two cases: one is installed in a processing chamber separately provided outside the plasma generation chamber as shown in FIG. 2, and the other is installed inside the plasma generation chamber as shown in FIG.

(Function) According to this configuration, the spread of the plasma generated by electron cyclotron resonance is determined by the aperture diameter of the microwave introduction window and is sufficiently wide, and the current density of the plasma in the plasma generation chamber is highly uniform. As a result, the entire surface of the substrate is uniformly irradiated with high-density plasma regardless of whether the substrate is inside or outside the plasma generation chamber. When the process is etching, especially when the substrate is installed in a plasma generation chamber, the process is performed under perpendicular magnetic lines of force, so the incident angle of ions is almost perpendicular at any location on the substrate surface, resulting in high-speed processing. This makes it possible to achieve highly uniform anisotropic etching.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a microwave plasma processing apparatus according to an embodiment of the invention of the present application.

The configuration of the apparatus shown in FIG. 1 is similar to the conventional apparatus shown in FIG. 2, except that the substrate is placed in a plasma generation chamber. Corresponding members are denoted by the same reference numerals and description thereof will be omitted.

A plasma generation chamber 1 that generates plasma by electron cyclotron resonance and a substrate transfer chamber 2' are configured to be adjacent to each other.

As mentioned above, the plasma generation chamber 1 is configured in a shape that conforms to the conditions of a microwave cavity resonator in order to increase the electric field strength of the microwave and increase the discharge efficiency. A core solenoid 3 is provided around the periphery.

This plasma generation chamber 1 is provided with a microwave introduction window 4 made of an insulator such as quartz glass or ceramics, and the opening diameter of the introduction window 4 is set to accommodate a substrate to be processed of 8"φ. , a diameter of 220 mmφ, which is larger than 8″φ, is used. From the microwave power source 6 to the waveguide 5
The microwaves sent through the plasma generating chamber 1 are introduced into the plasma generation chamber 1 through the introduction window 4.

A substrate holder 10 is installed in the plasma generation chamber 1, and a substrate to be processed is carried into the substrate transfer chamber 2'' from the outside by a transfer mechanism (not shown) and placed on the substrate holder 10, and the substrate is placed on the substrate holder 10. The holder 10 is raised to obtain the current state shown in the figure.High frequency power can be applied to the substrate holder 10 from a high frequency power source 11. 100 is an insulator.High frequency power is applied. When the impact force of the ions can be changed.

By making the opening diameter of the microwave introduction window 4 larger than the diameter of the substrate 12 to be processed, the results shown in FIG. 4 were obtained. That is, the absolute value of the ion current density in the plasma generation chamber 1 is 8 mA/
What was about cm2 increased to about 18 mA/cm2. The uniformity of the surface was also measured above the substrate 12,
It was found that the average value ±35% was improved to about ±6%.

In addition, when we actually processed a substrate in the plasma generation chamber,
It was found that this method has the effect of achieving uniform anisotropic etching at high speed.

When the substrate is retreated into the processing chamber 2 as shown in FIG. 2, by configuring the opening diameter of the plasma extraction window to be appropriately large, the plasma flow can be drawn out using a divergent magnetic field in the conventional method to process the substrate. Similar good results were obtained.

(Effects of the Invention) As explained above, the present invention makes the current density of plasma highly uniform in a microwave plasma processing apparatus, and irradiates a substrate to be processed with high-density plasma uniformly. This has the effect of uniform processing. When the process is etching, anisotropic etching has the effect of improving uniformity.

[Brief explanation of drawings]

FIG. 1 is a schematic front sectional view of a microwave plasma processing apparatus showing an embodiment of the present invention. FIG. 2 is a similar diagram of a conventional device. FIG. 3 shows the etched profile obtained by the conventional apparatus. FIG. 4 shows the distribution of ion current density. l... Plasma generation chamber, 2... Substrate processing chamber or substrate transfer chamber, 3... Air core solenoid coil, 4... Microwave introduction window, 5... Waveguide, 6... Microwave power supply, 7... Gas inlet, 8... Microwave (2.4
5GHz), 9...electron cyclotron resonance, 10.
...Substrate holder l1...High frequency bias power supply, 1
2... Substrate, 13... Plasma extraction window, 14...
...Mask material, 15...Etching pattern.

Claims (3)

[Claims] (1) Microwaves are introduced into a plasma generation chamber configured to meet the conditions of a microwave cavity resonator, and electron cyclotron resonance occurs due to the electric field generated by the microwaves and the magnetic field set perpendicular to the electric field. Microwave plasma processing equipment utilizes this phenomenon to turn processing gas into plasma, draws the plasma to a substrate using a divergent magnetic field, and processes the substrate by irradiating the substrate placed on a substrate holder. A microwave plasma processing apparatus characterized in that the opening area of a window introduced into the plasma generation chamber is larger than the area of the substrate to be processed. (2) A microwave plasma processing apparatus according to claim 1, characterized in that a high frequency bias voltage is applied to the substrate through a nuclear substrate holder. (3) Microwaves are introduced into a plasma generation chamber configured under the conditions of a microwave cavity resonator, and electron cyclotron resonance occurs due to the electric field generated by the microwaves and the magnetic field set perpendicular to the electric field. In a microwave plasma processing apparatus that uses this phenomenon to turn processing gas into plasma and processes the substrate by placing a substrate inside the plasma generation chamber, the opening area of the window through which microwaves are introduced into the plasma generation chamber is A microwave plasma processing apparatus characterized in that the area of the microwave plasma processing apparatus is larger than the area of the substrate.