WO2010119947A1

WO2010119947A1 - Plasma processing apparatus

Info

Publication number: WO2010119947A1
Application number: PCT/JP2010/056838
Authority: WO
Inventors: 真義池田; 洋田中; 勉廣石
Original assignee: キヤノンアネルバ株式会社
Priority date: 2009-04-16
Filing date: 2010-04-16
Publication date: 2010-10-21

Abstract

Provided is a means for preventing abnormal electrical discharge from being generated in a gap between a shield for a mask and a target electrode in a plasma processing apparatus. A plurality of magnet pieces (6) which form a point-cusped magnetic field are disposed also on the outer side of the outer circumferential end of a target electrode (2). A magnetic shield member (8) which covers at least a part of the magnetic surfaces of the magnetic pieces disposed on the outer side of the outer circumferential end is provided. Thus, the cusped magnetic field at the outer periphery of the target electrode is maintained, and the intensity thereof is adjusted such that no abnormal electrical discharge is generated in the gap between the target electrode and the shield for the mask.

Description

Plasma processing equipment

The present invention relates to a magnet mechanism for creating a plasma generating magnetic field. The magnet mechanism is used in a plasma processing apparatus for manufacturing a semiconductor device on a silicon substrate or another substrate.

Plasma assisted wafer processing is a well established process in the manufacture of semiconductor devices, usually called integrated circuits. Conventionally, there are many different plasma assisted processes such as etching, sputter deposition, chemical vapor deposition, and the like. All of these processes must be performed to achieve an etch rate or a uniform processing rate on the wafer surface. If non-uniform processing rates occur on the wafer surface, many defective semiconductor devices are produced.

The prior art will be specifically described below with reference to the conventional plasma processing apparatus shown in FIG. In the plasma processing apparatus, the chamber 201 that accommodates the target electrode 2 (first electrode) is composed of an upper wall (ceiling wall) 202, a cylindrical side wall 203, and a bottom wall 204. The upper electrode high frequency power supply 102 supplies high frequency power to the upper electrode 1 via the upper electrode matching machine 101. The lower electrode 301 (second electrode) includes a stage holder 302 and a lower electrode insulator 303. The lower electrode high-frequency power source 305 supplies high-frequency power to the stage 302 via the lower electrode matching unit 304. The gas in the chamber 201 is exhausted via the gas exhaust port 205. The plasma density on the surface of the target electrode 2 (first electrode) is changed by the divergent magnetic field on the outer periphery of the target electrode 2 (first electrode) created by the magnet mechanism that forms the point cusp magnetic field. The film forming rate of the wafer 306 is non-uniform, differing between the central part and the outer peripheral part.

Therefore, as shown in FIG. 5, a magnet mechanism 5 (consisting of a magnet 6 and a plate-like support 7) in which a magnet 6 is disposed outside the outer peripheral edge of the target electrode 2 (first electrode). The plasma density on the surface of the target electrode 2 (first electrode) is set so that the divergent magnetic field G is not generated on the surface of the target electrode 2 (first electrode). Patent Document 1 discloses an invention in which the film forming rate of the wafer 306 is uniform in the plane.

When such a conventional plasma processing apparatus is used for the sputtering process, a mask shield 3 is provided on the insulating member 4 and the target electrode 2 (first electrode) for supporting the target electrode in order to prevent adhesion of the film. There is a need. However, in the conventional plasma processing apparatus, there is a problem that the mask shield 3, the target electrode 2 (first electrode), and the insulating member 4 are damaged or cause an unstable process. There is not yet known what can eliminate this point as far as the person can know.

The problem with the conventional plasma processing apparatus described above is that, in the configuration shown in FIG. 5, the gap between the target electrode 2 (first electrode) and the mask shield 3 is equivalent to the surface of the target electrode 2 (first electrode). The magnetic field is formed. Due to this magnetic field, high-density plasma is formed between the target electrode 2 (first electrode) and the shield 3, and arcing (concentration of electric charges) is performed between the target electrode 2 (first electrode) and the mask shield 3. ) Occurs. It has been found that plasma having such high density is formed, causing damage to the target electrode 2 (first electrode), the insulating member 4 and the mask shield 3 due to abnormal discharge due to charge concentration and an unstable process. did. Therefore, it is necessary to form a magnet mechanism 5 that does not form a magnetic field in the gap between the target electrode 2 (first electrode) and the mask shield 3. Further, when a magnetic force line G generated from the magnet 6 disposed outside the outer peripheral edge of the target electrode 2 (first electrode) is generated beyond the mask shield 3, the mask shield 3 and the cylindrical side wall 203 are interposed. It has been found that abnormal discharge occurs, causing damage to the mask shield 3 and the cylindrical side wall 203 and an unstable process.

JP2003-318165

Therefore, the present invention aims to solve the above-described problems, and has a magnet mechanism that does not form a strong magnetic field that causes abnormal discharge in a gap portion between the target electrode (first electrode) and the mask shield. An object of the present invention is to provide a plasma processing apparatus.

The plasma processing apparatus according to the present invention includes a first electrode serving as a target electrode, a second electrode serving as an anode that supports the substrate, and is disposed between the first and second electrodes. A mask shield disposed adjacent to the first electrode with a predetermined gap and disposed in the vicinity of the outer periphery of the first electrode, and the first electrode on the opposite side of the second electrode with respect to the first electrode A magnet arranged on the electrode surface, the magnet comprising a plurality of magnet pieces distributed on the first electrode surface for generating a magnetic field on the second electrode side with respect to the first electrode. A plasma processing apparatus for generating plasma in a space between the first and second electrodes and applying a target material of the first electrode when a voltage is applied to the first and second electrodes, Part of the magnet piece for magnetic field generation exceeds the outer periphery of the first electrode Extends on the outside, characterized in that it comprises a magnetic shielding member disposed so as to cover at least a portion of the pole faces of the magnet pieces arranged on the outside.
In this embodiment, the magnetic shielding member is disposed at a position between the magnet and the first electrode.

In this specification, “the magnetic field is not formed in the gap between the target electrode and the mask shield” or “the magnetic field formed by the magnet mechanism is not formed on the outer periphery between the first electrode and the second electrode. "Means that the magnetic field is not formed to such an extent that abnormal discharge is not formed. Therefore, the material of the magnetic shielding member may be any material that can suppress the magnetic field strength, and it is preferable to use a material (SUS430 or the like) having a higher magnetic permeability than the material provided in the chamber.

The plasma processing apparatus equipped with the magnet mechanism according to the present invention forms a magnetic field necessary for sputtering film formation up to the outermost periphery of the target electrode, and does not form a magnetic field in the gap between the target electrode and the shield. As a result, "A necessary plasma density is generated up to the outermost periphery of the target electrode to obtain a uniform film thickness within the wafer surface" and "High density plasma is not formed in the gap between the target electrode and the shield by the magnetic field. Thus, it is possible to satisfy both of the target electrode and shield breakage due to charge concentration and the elimination of process instability caused by plasma instability.

It is sectional drawing of the plasma processing apparatus according to the Example of this invention. It is a figure which shows the plasma when a magnet piece is provided in the target outer periphery. It is a figure which shows the plasma erosion (ED) when a magnet piece is provided in the target outer periphery. It is a figure which shows the mode of a magnetic field and plasma when a magnet piece is provided in the target outer periphery. It is a figure which shows the plasma when a magnet piece is provided outside the target outer periphery. It is a figure which shows the plasma erosion (ED) when a magnet piece is provided outside the target outer periphery. It is a figure which shows the mode of a magnetic field and plasma when a magnet piece is provided out of the target outer periphery. It is a figure which shows the plasma at the time of arrange | positioning the magnetic shielding member of this invention with the magnet piece provided outside the target outer periphery. It is a figure which shows plasma erosion (ED) at the time of providing the magnet piece outside the outer periphery of a target, and arrange | positioning the magnetic shielding member of this invention. It is a figure which shows the mode of a magnetic field and a plasma at the time of providing the magnet piece outside the outer periphery of a target, and arrange | positioning the magnetic shielding member of this invention. It is sectional drawing of the conventional plasma processing apparatus.

[Description of Examples]
An embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of a plasma processing apparatus 100 equipped with a magnet mechanism 5 according to the embodiment. The plasma processing apparatus 100 includes a target electrode 2 (first electrode) that is a first electrode as a cathode, a chamber 201, and a lower electrode that is a second electrode as an anode provided facing the first electrode. 301. A mask shield 3 is disposed below the target electrode 2 (first electrode) with a gap provided between the chamber electrode 201 and the upper electrode to hold the target electrode 2 (first electrode). An insulator 4 is attached. Above the target electrode 2 (first electrode), a magnet mechanism 5 for forming a point-caps magnetic field for plasma generation is disposed away from the target electrode 2. The magnet mechanism 5 includes a plurality of magnet pieces 6, a magnet support plate 7, and a magnetic shielding member 8. Process gas is supplied into the chamber 201 through a plurality of gas inlets 9.

The chamber 201 including the target electrode 2 (first electrode) supported by the insulating member 4 includes an upper wall (ceiling wall) 202, a cylindrical side wall 203, and a bottom wall 204. The lower electrode 301 (second electrode) includes a stage holder 302 and a lower electrode insulator 303. The basic hardware structure of the plasma processing apparatus 100 of the first embodiment is the same as that described as the prior art except for the magnetic shielding member 8 made of a magnetic material. The target electrode 2 (first electrode) is disposed above the chamber 201 and is electrically insulated from the chamber 201 via the upper electrode insulator 4. The main part of the target electrode 2 (first electrode) is made of a nonmagnetic metal such as Al, SUS, or Cu, but the reduced pressure side of the target electrode 2 (first electrode) corresponding to the lower surface of the upper electrode 1 For this, a material target material necessary for forming a film on the wafer 306 is installed. In the figure, the target material is not shown. In addition, the upper electrode 1 can be cooled by flowing cooling water through a passage formed in the upper electrode 1 or the target electrode 2 (first electrode). The passage through which the cooling water flows is not shown in FIG.

The upper electrode high frequency power supply 102 supplies high frequency power to the upper electrode 1 via the upper electrode matching machine 101. The upper electrode high-frequency power source 102 is used in the range of 10 to 300 MHz. It is also possible to apply a DC voltage to the upper electrode 1 by a DC power source (not shown). Process gas is supplied into the chamber 201 through the gas inlet 9. The chamber 201 is exhausted by the vacuum exhaust pump 10 via the gas exhaust port 205. The lower electrode 301 includes a stage holder 302 and a lower electrode insulator 303. The stage holder 302 is fixed to the bottom wall 204 via a lower electrode insulator 303, and the stage holder 302 and the chamber 201 are electrically insulated by the lower electrode insulator 303. The wafer 306 is placed on the upper surface of the stage holder 302. In addition, the lower electrode 301 can control the wafer 306 to a temperature necessary for film formation by installing the cooling mechanism 12 and the heating mechanism 12 in the lower electrode 301 and the stage holder 302. In addition, an electrostatic adsorption stage can be mounted on the stage holder 302, and a DC power source can be connected to the stage holder 302 to adsorb the wafer 306 and control the temperature. The lower electrode high frequency power source 305 supplies high frequency power to the lower electrode 301 via the lower electrode matching machine 304. The frequency of the high frequency power used is 20 MHz or less.

An important feature of the magnet mechanism 5 is that the magnetic shielding member 8 is disposed between the magnet piece 6A located outside the outer peripheral edge of the target electrode 2 (first electrode) and the target electrode 2 (first electrode). The magnet piece 6 is installed so as to cover the lower end surface, that is, a part of the magnetic pole surface, and controls the magnetic field strength of the gap between the target electrode 2 (first electrode) and the mask shield 3. The magnetic field adjusting magnetic shielding member 8 may be a material that can control the magnetic field strength of the gap between the target electrode 2 (first electrode) and the mask shield 3. For example, a material having a high magnetic permeability such as SUS430 is preferable. . This magnet mechanism 5 sputters the target electrode 2 (first electrode) material to the outermost periphery of the target electrode 2 (first electrode) by adjusting the area covered by the magnetic shielding member 8 on the magnet piece 6A. The magnetic field is adjusted so as not to supply a magnetic field strong enough to cause abnormal discharge in the gap between the target electrode 2 (first electrode) and the mask shield 3. Therefore, the function of the magnetic shielding member 8 according to the present invention is not such that the magnetic field is completely extinguished in the gap between the target electrode 2 and the mask shield 3, but abnormal discharge is maintained while maintaining the capsular magnetic field around the target electrode. The magnetic field adjustment is performed to weaken the magnetic field in the gap to the extent that does not occur. This magnetic field adjustment is determined on the balance of avoiding abnormal discharge and erosion of the outer periphery of the target electrode 2.

The operation of the present invention will be further described with reference to FIGS. FIG. 2A is a plan view in the case where the magnet piece 6 is provided only inside the target surface, and a portion P having a high plasma density is generated between the magnet pieces 6. The outer peripheral edge of the target 2 and the inner peripheral edge R of the mask shield 3 are shown as R in the drawing on the assumption that they substantially coincide. FIG. 2B shows the degree of plasma erosion (erosion) ED on the surface of the target 2 on the line AB in FIG. 2A. r is the distance from the target center. There is little ED at the center (r = 0), and there is little ED near the outer periphery of the target. FIG. 2C is a cross-sectional view taken along the line AB of FIG. 2A and shows the state of the magnetic field and plasma. In this case, the plasma P is not generated between the mask shield 3 and the target 2, and it is difficult for the discharge to occur. However, as shown in FIG. 3B, the erosion particularly outside the target is not sufficiently obtained. As a result, the margin of process conditions that can uniformly control the film thickness on the wafer is narrow, and the utilization efficiency of the target is low.

FIG. 3A is a plan view in the case where the magnet piece G is provided outside the target surface, and high-density plasma P is generated between the magnet piece 6A on the outside and the surrounding magnet pieces. This high-density plasma P is also generated on the outer peripheral edge of the target 2 and the inner peripheral edge R of the mask shield 3, and abnormal discharge is likely to occur in the black circle portion D in FIG. 4A. FIG. 3B shows the degree of ED on the surface of the target 2 on the line AB in FIG. 4A. The solid line is the data when the magnet piece of FIG. 3A is also outside the target 2, and the dotted line is the data for FIG. 2A. It will be understood from this ED data comparison that a sufficient ED is obtained at the outer periphery of the target. FIG. 3C is a cross-sectional view taken along the line AB of FIG. 3A and shows the state of the magnetic field and plasma. The outermost magnet piece 6A forms a divergent magnetic field on the outer side, and high-density plasma is generated between the magnet piece 6 and the high-density plasma exists in the gap between the target 2 and the mask shield 3, and abnormal discharge occurs. Is likely to occur.

FIG. 4A is a plan view in the case where a part of the magnetic pole surface of the magnet piece 6A outside the target 2 is covered with a magnetic shielding member, corresponding to the embodiment of FIG. 1 of the present invention. A high-density plasma P is generated between the magnet pieces 6 inside the target 2, and a plasma P ′ in which the plasma density is suppressed to such an extent that abnormal discharge does not occur between the magnet pieces 6 </ b> A outside. FIG. 4B shows the degree of ED on the surface of the target 2 on the line AB in FIG. 4A. The solid line is the data of the present invention in which the magnet piece of FIG. 4A is provided outside the target and the magnetic shielding member 3 covers a part of the magnetic pole surface of the magnet piece arranged on the outside, and the dotted line is the case of FIG. 2A It is data. As in the case of FIG. 3B, the degree of ED is sufficient for the outer peripheral edge of the target. FIG. 4C is a cross-sectional view taken along the line AB of FIG. 4A and shows the state of the magnetic field and plasma. At least a part of the magnetic pole surface of the outermost magnet piece 6A is covered with the magnetic shielding member 8 so that a divergent magnetic field is not formed, and the plasma P ′ near the outer peripheral edge of the target 2 is in contact with the mask shield 3. The density is suppressed to such an extent that abnormal discharge does not occur. By doing so, plasma erosion (ED) is performed to the outer periphery of the target 2. As a result, the margin of process conditions that can uniformly control the film thickness on the wafer is widened, and the utilization efficiency of the target is improved. Further, since the divergent magnetic field is also suppressed, abnormal discharge between the chamber side wall 203 due to the divergent magnetic field can be prevented.

2 Target electrode (first electrode)
301 Anode (second electrode)
5

Magnet mechanism

6, 6 A Magnet piece 3 Mask shield 8 Magnetic shielding member

Claims

A first electrode (2) as a target electrode which is a cathode;
A second electrode (302) provided opposite to the first electrode and serving as an anode for supporting the substrate;
A mask shield (3) disposed between the first electrode and the first electrode adjacent to the first electrode with a predetermined gap and disposed in the vicinity of the outer periphery of the first electrode; and A magnet mechanism (5) disposed on the first electrode surface opposite the second electrode with respect to the first electrode, the magnetic mechanism being on the second electrode side with respect to the first electrode. Comprising a magnet mechanism comprising a plurality of magnet pieces (6) distributed on the first electrode surface for generating
In a plasma processing apparatus for generating a plasma in a space between the first and second electrodes when a voltage is applied to the first and second electrodes and sputtering a target material of the first electrode,
A part of the plurality of magnet pieces for generating a magnetic field extends outward beyond the outer peripheral edge of the first electrode,
A plasma processing apparatus comprising a magnetic shielding member (8) disposed to cover at least a part of a magnetic pole surface of a magnet piece (6A) disposed on the outside.
2. The plasma processing apparatus according to claim 1, wherein the magnetic shielding member is disposed at a position between the magnet and the first electrode.