JP2006318725A - Inductively coupled plasma production device and plasma production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inductively coupled plasma production device uniformalizing a film-forming or an etching speed in a wide area, through control of space distribution of plasma. <P>SOLUTION: The inductively coupled plasma production device turning gas supplied inside a chamber 1 to plasma, and carrying out film-forming and etching treatments against a substrate 3 with the use of the plasma, is so structured that a plurality of independent induction coils 4A, 4B are arranged concentrically inside and outside, and at the same time, phases of high-frequency current supplied to the respective induction coils 4A, 4B are to be independently controlled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inductively coupled plasma generation apparatus and a plasma generation method, and is particularly useful when applied to a plasma CVD apparatus and an etching apparatus that perform predetermined film formation and etching in a vacuum vessel.

  The inductively coupled plasma generator is configured to arrange a high-frequency induction coil for forming an induction electric field on a ceiling plate of a vacuum-evacuated chamber and generate plasma of gas to be supplied into the chamber by the induction electric field generated by the induction coil. This is for performing film formation or etching on the substrate placed in the chamber.

  Here, the plasma distribution in the chamber changes due to the arrangement of the induction coil, the gas pressure in the chamber, the shape of the chamber, and the like. Therefore, in order to improve the uniformity of the film formation and etching process on the substrate, it has been based on hardware measures such as position adjustment to optimize the substrate position (vertical direction) and optimization of the shape of the induction coil.

However, in order to adjust the vertical position of the substrate position, it is not only necessary to add a position adjustment mechanism, but there is a problem that the throughput of the process is lowered due to the vertical movement. In particular, when it is necessary to perform film formation and etching simultaneously as in the case of SiO ₂ film formation, it may be difficult to satisfy both the uniformity of film formation and etching only by adjusting the substrate position.

  On the other hand, it is necessary to determine the shape of the induction coil by determining process conditions in advance, and subsequent changes and adjustments are difficult.

  In general, the plasma distribution in the chamber tends to decrease from the center along the radial direction toward the chamber wall, and there is a problem that it is necessary to compensate for this to ensure uniformity.

  As a known technique similar to the present invention, there is a technique for controlling a plasma distribution by controlling a current of the induction coil by connecting a capacitor or an inductance in series with the induction coil in a circuit having a plurality of induction coils. (See Patent Document 1).

  However, this conventional technique controls the amount of current in each induction coil by changing the impedance of the induction coil using a capacitor or inductor inserted in series. Therefore, it is limited to the control of the plasma distribution in the range of the superposition of the same direction magnetic field created by each induction coil. Further, the plasma distribution cannot be made uniform by temporally oscillating.

JP 2002-124399 A JP 2002-033306 A JP 2003-188153 A JP 07-263188 A

  An object of the present invention is to provide an inductively coupled plasma generating apparatus and a plasma generating method that control the spatial distribution of plasma to make the film formation or etching rate uniform over a wide area.

The first aspect of the present invention for solving the above problems is as follows.
A chamber which is a vacuum container, a substrate disposed in the chamber, and an induction coil to which a high-frequency current is supplied, and plasma is supplied to the gas supplied into the chamber by a high-frequency electric field formed by the induction coil. In an inductively coupled plasma generation apparatus that performs film formation and etching processing on the substrate using this plasma,
A plurality of independent induction coils are concentrically arranged inside and outside, and the phase of the high-frequency current supplied to each induction coil can be controlled independently.

The second aspect of the present invention is:
In the first aspect, each induction coil is individually connected to each high-frequency power source, and is configured to adjust the phase of the high-frequency current output from each high-frequency power source.

The third aspect of the present invention is:
In the first aspect, there is provided a distributor that distributes a plurality of high-frequency currents output from the high-frequency power source, and a phase shifter that controls the phase of the high-frequency current distributed by the distributor, and the phase is controlled by one high-frequency power source. Is configured to supply different high frequency currents to the induction coils.

The fourth aspect of the present invention is:
In any one of the first to third aspects, the substrate is formed to be movable up and down in the chamber so that the relative positional relationship of the substrate with respect to the plasma can be adjusted.

According to a fifth aspect of the present invention,
In any one of the first to fourth aspects, a phase difference between one high-frequency current supplied to the relatively outer induction coil and another high-frequency current supplied to the relatively inner induction coil is 180 degrees. And the high-frequency current supplied to the outer induction coil is made larger than the high-frequency current supplied to the inner induction coil.

The sixth aspect of the present invention is:
Plasma for forming a film or etching a substrate disposed in the chamber by converting the gas supplied into the chamber, which is a vacuum vessel, into plasma by a high-frequency electric field formed by an induction coil to which a high-frequency current is supplied In the plasma generation method for generating
Independently controlling the phase of the high-frequency current supplied to a plurality of induction coils arranged concentrically inside and outside, and controlling the spatial distribution of the plasma to be uniform over a wide range in the radial direction of the chamber. Features.

  According to the present invention, in the inductively coupled plasma generating apparatus, uniform and uniform film formation or etching can be performed by controlling the phase of the current of the plurality of induction coils. That is, uniform or uniform film formation or etching is possible by electrical control (electrical control) without changing the hardware surface such as the shape and arrangement of the induction coil.

  Furthermore, it can be easily combined with conventional substrate position adjusting means and the like, and when combined, further controllability can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description of the present embodiment is an exemplification, and the configuration of the present invention is not limited to the following description.

<First Embodiment>
FIG. 1 is an explanatory view conceptually showing the inductively coupled plasma generating apparatus according to the first embodiment of the present invention. As shown in the figure, the inductively coupled plasma generating apparatus according to the present embodiment is supplied with a high-frequency current from a chamber 1 that is a vacuum vessel, a substrate 3 placed on a support base 2 disposed in the chamber 1, and A gas supplied into the chamber 1 with a high-frequency electric field formed by the induction coil 4, and the plasma is used for film formation and etching on the substrate 3. Is what you do.

  As shown in detail in FIG. 2 by extracting this part in particular, the induction coil 4 has a plurality of independent induction coils 4A and 4B having different radii (two in this embodiment) arranged concentrically inside and outside. Configured. Here, the feeding points A and B for supplying the high-frequency current of the induction coils 4A and 4B are arranged at positions different by 180 degrees on the same plane. Although it is not essential to change the positions of the feeding points A and B in this way, the plasma distribution in the radial direction of the chamber 1 can be made uniform by adopting such a configuration. That is, since the feeding points A and B have rising portions in the vertical direction of the induction coils 4A and 4B, the electric field and the magnetic field are disturbed in this portion, and consequently, the plasma is disturbed. Therefore, when the feeding points A and B are concentrated at the same position, the plasma disturbance is also concentrated. However, when the feeding points A and B are dispersed as described above, the plasma disturbance can be dispersed. Accordingly, the plasma density in the chamber 1 can be made uniform.

  Each induction coil 4A, 4B is configured to be able to independently control the phase of the high-frequency current supplied thereto. That is, a high frequency power source 5A is connected to the induction coil 4A via an amplifier 6A and a matching unit 7A, and a high frequency power source 5B is connected to the induction coil 4B via an amplifier 6B and a matching unit 7B. 4B can control the phase of the high frequency current which is each output current independently.

  In the inductively coupled plasma generating apparatus of this embodiment, the phase difference can be created by changing the phase of each high-frequency current output from the high-frequency power supplies 5A and 5B. Here, when the phase difference of the high-frequency current is 180 degrees, the direction of the high-frequency current flowing through the induction coils 4A and 4B is always opposite to the positive and negative directions, and when it is 90 degrees, the sign of both high-frequency current directions changes with time. To do. Therefore, by changing the magnetic field (induction electric field) generated by each high-frequency current flowing through each induction coil 4A, 4B by controlling the phase difference, the plasma spatial distribution can be changed between steady and unsteady.

  At this time, by setting the high-frequency current supplied to the outer induction coil 4A to be larger than the high-frequency current supplied to the inner induction coil 4B, the region of maximum electric field density is set in the chamber 1 with respect to the radial direction of the chamber 1 directly below the induction coil 4A. Shift to the wall surface side of 1. As a result, the plasma distribution can be expanded to the vicinity of the wall surface of the chamber 1 to form a more uniform plasma distribution.

  FIG. 3 shows the plasma distribution I when the high-frequency current supplied to the outer / inner induction coils 4A and 4B has an opposite phase (phase difference of 180 degrees) and is supplied at a rate of 150 / -50 respectively. . For comparison, FIG. 4 shows a plasma distribution II when currents are passed through the two induction coils 4A and 4B in the same phase. In both figures, the position of 0.0 on the horizontal axis coincides with the central axis of the chamber 1, the position of W coincides with the wall surface position of the chamber 1, and the position of H on the vertical axis indicates the ceiling plate position of the chamber 1. , And the portion of reference numeral 3 matches the substrate position. FIG. 5 is a graph showing a comparison result of the uniformity of ion flux at the position of the substrate 3. This graph displays numerical values obtained by normalizing the value of (MAX−MIN) / (MAX + MIN) with reference to the case of II using the maximum value MAX and the minimum value MIN of the ion flux. Therefore, the smaller the numerical value, the more uniform.

  As is apparent from these drawings, the plasma distribution I can be extended to the vicinity of the wall surface of the chamber 1 in the case of this embodiment shown in FIG. That is, the phase difference of 180 degrees can maintain the plasma at a position closer to the wall surface of the chamber 1. As a result, the loss of the plasma on the wall surface is compensated, and the plasma distribution I over a wider range on the substrate 3. Becomes uniform.

  Further, when the phase difference of the high-frequency current supplied to the induction coils 4A and 4B is 90 degrees, the position where the plasma excitation current is maximized changes every high-frequency current 1/4 cycle. It can be changed dynamically. That is, by performing phase control that arbitrarily changes the phase difference θ in the range of 0 ° <θ ≦ 180 °, the plasma distribution I can be controlled according to the purpose without changing the positions of the induction coils 4A and 4B. It becomes possible.

<Second Embodiment>
FIG. 6 is an explanatory view conceptually showing the inductively coupled plasma generating apparatus according to the second embodiment of the present invention. As shown in the figure, the inductively coupled plasma generating apparatus according to the present embodiment is different from the first embodiment shown in FIG. 1 only in the configuration of the power feeding system for supplying the induction coil 4 with a high-frequency current. This is the same as the inductively coupled plasma generating apparatus according to the embodiment. Therefore, in FIG. 6, the same parts as those in FIG.

  As shown in FIG. 6, in the inductively coupled plasma generating apparatus according to the present embodiment, there is one high-frequency power supply 15, but the phase of the high-frequency current supplied to each induction coil 4A, 4B can be controlled independently. It is configured. That is, the high-frequency current output from the high-frequency power supply 15 is distributed by the distributor 18, and one of them is supplied to the induction coil 4A via the amplifier 6A and the matching unit 7A. On the other hand, the phase of the other high-frequency current distributed by the distributor 18 is controlled to a predetermined phase by the phase shifter 19 and supplied to the induction coil 4B via the amplifier 6B and the matching unit 7B.

  Also in the inductively coupled plasma generator of this embodiment, the phase difference of the high frequency current supplied to each induction coil 4A, 4B can be made by changing the phase of the high frequency current output from the high frequency power supply 15. That is, the same plasma distribution as in the first embodiment can be formed by phase control in the phase shifter 19.

  As described above, according to the present invention, in the inductively coupled plasma apparatus using a plurality of induction coils, the spatial distribution of plasma can be controlled by changing the phase of the high-frequency current supplied to each induction coil. Also, the temporal spatial distribution can be controlled by appropriately selecting the time constant of the phase change.

  The conventional substrate position adjusting means for controlling the position of the substrate by moving it up and down can be combined with the inductively coupled plasma generating apparatus according to the first or second embodiment. In this case, the relative positional relationship between the substrate and the plasma can be appropriately controlled by the substrate position adjusting means, and the plasma density in the chamber can be made uniform. Can do.

  INDUSTRIAL APPLICABILITY The present invention can be used in the industrial field relating to the manufacture and sale of apparatuses for performing processes such as film formation and etching for manufacturing semiconductor devices.

It is explanatory drawing which shows notionally the inductively coupled plasma generating apparatus which concerns on the 1st Embodiment of this invention. FIG. 2 is an enlarged view showing a part extracted from FIG. 1 in detail. It is explanatory drawing which shows the plasma distribution I when the high frequency electric current supplied to an outer / inner induction coil becomes an antiphase (phase difference 180 degree | times), and is supplied in the ratio of 150 / -50, respectively. It is explanatory drawing which shows plasma distribution II at the time of supplying an electric current with the same phase to two induction coils for the comparison with the plasma distribution shown in FIG. It is a graph which shows the comparison result of the uniformity of the ion flux in the position of the board | substrate in a chamber. It is explanatory drawing which shows notionally the inductively coupled plasma generation apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

I, II Plasma distribution 1 Chamber 2 Support base 3 Substrate 4, 4A, 4B Inductive coil 5A, 5B High frequency power source 15 High frequency power source 18 Distributor 19 Phase shifter

Claims (6)

A chamber which is a vacuum container, a substrate disposed in the chamber, and an induction coil to which a high-frequency current is supplied, and plasma is supplied to the gas supplied into the chamber by a high-frequency electric field formed by the induction coil. In an inductively coupled plasma generation apparatus that performs film formation and etching processing on the substrate using this plasma,
An inductively coupled plasma generating apparatus characterized in that a plurality of independent induction coils are arranged concentrically inside and outside and the phase of a high-frequency current supplied to each induction coil can be controlled independently. In claim 1,
Each induction coil is individually connected to each high-frequency power source, and is configured to adjust the phase of a high-frequency current output from each high-frequency power source. In claim 1,
It has a distributor that distributes the high-frequency current output from the high-frequency power supply into multiple parts, and a phase shifter that controls the phase of the high-frequency current distributed by this distributor. An inductively coupled plasma generating apparatus characterized by being configured to supply to a coil. In any one of Claims 1 to 3,
An inductively coupled plasma generating apparatus, wherein the substrate is formed so as to be movable up and down in the chamber, and the relative positional relationship of the substrate with respect to the plasma can be adjusted. In any one of Claim 1 thru | or 4,
The phase difference between one high-frequency current supplied to the relatively outer induction coil and the other high-frequency current supplied to the relatively inner induction coil is set to 180 degrees, and the high-frequency current supplied to the outer induction coil Is made larger than a high-frequency current supplied to the inner induction coil. Plasma for forming a film or etching a substrate disposed in the chamber by converting the gas supplied into the chamber, which is a vacuum vessel, into plasma by a high-frequency electric field formed by an induction coil to which a high-frequency current is supplied In the plasma generation method for generating
Independently controlling the phase of the high-frequency current supplied to a plurality of induction coils arranged concentrically inside and outside, and controlling the spatial distribution of the plasma to be uniform over a wide range in the radial direction of the chamber. A plasma generation method.

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