JPH0936088A - Plasma treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an insulation film in a holder electrode from plasma while preventing the nonuniformity in plasma treatment and generation of dust at the peripheral part of an object to be treated by providing a shade member for covering the peripheral part of the object being installed on the insulation film while keeping insulation space for it. SOLUTION: A ring-shaped electrical insulation member 7 when viewed from the top is arranged at the peripheral part of a holder electrode 2 and an inner-periphery part 72 of the ring-shaped overhang-shaped insulation member 7 is installed on the peripheral upper surface of an insulation film 21 on the electrode 2. A ring-shaped shade member 8 when viewed from the top is arranged at the upper portion of the overhang-shaped insulation member 7 and a shade member 8 can approach or leave a peripheral part s1 of an object S to be treated installed on the electrode 2. A top surface 70 of the overhang- shaped insulation member 7 is a stopper for determining the approach limit to the object S of the shade member 8 for setting an insulation space X between the shade member 8 and the object S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for converting a processing gas into plasma and subjecting an object to be processed under the gas plasma, and more particularly, to a holder electrode also serving as an object holder. An object to be processed is placed in a chamber, and a processing gas is introduced under a predetermined vacuum between the holder electrode and an electrode for the holder electrode (an electrode opposite to the holder electrode, or a plasma processing chamber itself also serving as an electrode). The present invention relates to a plasma processing apparatus in which the introduced gas is turned into plasma by applying high-frequency power between the electrodes, and an object to be processed is subjected to the target processing under the plasma.

[0002]

2. Description of the Related Art As a plasma processing apparatus of this type, various dry etching apparatuses using gas plasma, plasma CVD apparatus, etc. are known. In some cases, the object to be processed may have to be heated appropriately. For example, reactive ion etching (R
In a dry etching apparatus such as an IE) apparatus, a plasma etching apparatus, an ECR plasma etching apparatus, and a magnetron RIE apparatus, the temperature of an object to be processed exposed to plasma usually rises, but this temperature rise causes various inconveniences. For example, when a pattern is drawn with a resist on a film which is a base for forming a wiring pattern or the like on a semiconductor wafer or a glass substrate for a liquid crystal display device and dry etching is performed, the resist is damaged by heat and deteriorated. As a result, a situation may occur in which a predetermined pattern cannot be etched or the wafer itself is damaged. Therefore, the object to be etched is usually cooled. In a plasma CVD apparatus, a film formation target may be heated as necessary in order to efficiently form a desired film.

As described above, various temperature control methods for the object to be cooled or heated have been proposed, and one of the typical methods is the temperature control by the electrostatic adsorption method. This is because while the holder electrode for setting the object to be processed can be temperature-controlled by an appropriate means, the object to be processed is installed on the holder electrode via an electric insulating film, and thus the object to be processed under plasma is processed. Electric charges are accumulated on the object by self-bias action, and a DC voltage is applied to the holder electrode to accumulate electric charges of opposite polarities, and the object to be treated is adsorbed on the holder electrode by the action of electrostatic force due to these both charges. The temperature of the object to be processed is controlled from the electrode. When controlling the temperature of the object to be processed by adopting the electrostatic adsorption method in this way, as described above, the insulating film is laid on the holder electrode, and the object to be processed is placed on it. A peripheral portion of the insulating film which is not covered with the object to be processed is damaged when exposed to plasma. Therefore, usually, a ring-shaped clamp ring member is pressed and closely attached to the peripheral edge of the object to be processed on the insulating film to shield the insulating film from plasma and protect it.

[0004]

However, in the clamp type contact plasma shield in which the clamp ring member is pressed and closely adhered to the peripheral edge of the object to be processed, the clamp ring member mechanically and thermally contacts the object to be processed. In order to
During plasma processing, heat conduction occurs between the clamp ring member and the object to be processed, resulting in non-uniform temperature between the peripheral portion and other parts of the object to be processed. Is non-uniform.

Further, since the clamp ring member mechanically contacts the object to be processed, dust is generated at the peripheral portion of the object to be processed, which has a problem of adversely affecting the plasma processing. For example, in the etching process, there is a problem in that the resist provided to cover the non-etched portion on the surface of the object to be processed adheres to the clamp ring member and is peeled off to become dust, which causes etching failure.

Therefore, in the present invention, the object to be processed is placed on the holder electrode which can control the temperature and also serves as the object holder via the insulating film, and the holder electrode and the object to be processed under a predetermined vacuum. Electrode (electrode placed opposite the holder electrode,
(A plasma processing chamber itself also serving as an electrode, etc.) is introduced into the processing gas by applying a high-frequency electric power between the electrodes by applying a high-frequency power between the two electrodes, and the plasma is applied to the object to be processed under the plasma. A plasma processing apparatus of a type that performs a target process and controls the temperature of the object to be processed while electrostatically adsorbing the object to the holder electrode by applying a DC voltage to the holder electrode during the process. That is, non-uniformity of the plasma processing due to the non-uniformity of the temperature in each part of the object to be processed, such as when using a conventional clamp-type contact plasma shield, while preventing the generation of dust in the peripheral part of the object to be processed, An object of the present invention is to provide a plasma processing apparatus capable of protecting the insulating film in the holder electrode from plasma.

[0007]

In order to solve the above-mentioned problems, the present invention relates to a plasma processing apparatus of the type described above, wherein the peripheral portion of the insulating film not covered by the object to be processed is protected from plasma. Provided is a plasma processing apparatus, which is provided with a shade member (eave-shaped member) for covering a peripheral portion of an object to be processed, which is installed on an insulating film, while keeping an insulating space.

Here, the insulating space between the shade member and the peripheral portion of the object to be processed is not mechanically or thermally contacted with each other within a range in which the insulating film on the holder electrode is not exposed to plasma. It is an insulating space for. The distance between the shade member and the peripheral portion of the object to be processed for obtaining this insulating space is generally 0.
For example, it can be about 3 mm to 0.8 mm.

The shade member (overhanging member) is usually, but not limited to, a ring shape. According to the plasma processing apparatus of the present invention, the object to be processed is placed on the insulating film in the holder electrode, the processing gas is introduced between the holder electrode and the electrode corresponding thereto under a predetermined vacuum, and the space between the electrodes is increased. High-frequency power is applied to the gas, and the gas is turned into plasma, and the object to be processed is subjected to the target treatment under the plasma.

During this processing, the holder electrode is controlled to a predetermined temperature according to the processing temperature of the object to be processed, and a DC voltage is applied to the holder electrode to electrostatically adsorb the object to be processed to the holder electrode. Thus, the object to be processed is controlled to a predetermined temperature from the temperature-controlled holder electrode through the insulating film. In addition, the insulating film on the holder electrode is protected from plasma by covering the peripheral edge of the object to be processed placed thereon with a shade member. At this time, since the shade member covers the peripheral edge of the object to be processed through a space that is mechanically and thermally insulated from the peripheral edge of the object to be processed, the shade member and the object to be processed are conventionally separated from each other. Unlike the clamp-type close contact plasma shield, heat conduction does not occur. Therefore, the temperature of each part of the object to be processed is made uniform, and the plasma processing of each part of the object to be processed is made uniform, and the shade member is the peripheral edge of the object to be processed. Since there is no mechanical contact with the part, generation of dust at the peripheral edge of the object to be processed is prevented, and good plasma processing is carried out without being affected by the dust.

In the plasma processing apparatus of the present invention, a dark space shield may be provided outside the peripheral side surface of the holder electrode with a predetermined gap in order to prevent plasma from being generated at unnecessary points. Further, in this case, when there is a large potential difference between the holder electrode and the dark space shield and there is a risk of discharge occurring between the two, in order to prevent this, the opening of the gap between the holder electrode and the dark space shield should be opened. An eave-shaped insulating member may be provided so as to extend from the peripheral edge of the holder electrode so as to cover it. Further, in this case, in order to prevent the discharge more reliably, the eaves-shaped insulating member may be formed to have an outer end bent so as to surround the outer surface of the end of the dark space shield facing the gap opening.

In any case, the shade member can be provided so as to be able to approach and separate from the object to be processed placed on the holder electrode. In this case, when the eave-shaped insulating member is provided, the shade member is provided. The strip-shaped insulating member can be a stopper that defines an approach limit of the shade member to the object to be processed for setting the insulating space between the shade member and the object to be processed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a dry etching apparatus as an example of a plasma processing apparatus according to the present invention. The etching apparatus shown in FIG. 1 includes an etching processing chamber 1, and a holder electrode 2 is provided at the bottom of the chamber 1.

A gas supply unit 4 for supplying an etching gas and an exhaust device 5 (gate valve 51 and dry pump 52) for evacuating the chamber 1 are connected to the chamber 1. An electrically insulating film 2 is formed on the upper surface of the holder electrode 2.
1 has been laid. The electrode 2 is installed on the chamber bottom wall 11 via an electrical insulator 20, and is connected to a high frequency power source 32 via a matching box 31. A DC power supply 33 is also connected to the electrode 2, and an LC circuit 34 for blocking high frequency from the high frequency power supply 32 is provided between the DC power supply 33 and the electrode 2.

In this apparatus, the chamber 1 is grounded so as to function as an electrode for the holder electrode 2. The holder electrode 2 has a cooling refrigerant circulation passage 21a built therein, and a refrigerant circulation device (here, a cooling water circulation device) 21b is connected to the passage, whereby the holder electrode 2
The temperature can be controlled.

A cylindrical dark space shield 6 is arranged outside the peripheral side surface of the holder electrode 2 with a small gap D surrounding the peripheral side surface, which is a chamber bottom wall 11.
It is erected on the top and is at the same potential as the chamber 1 (ground potential). The upper end of the dark space shield 6 is located slightly below the upper surface of the electrode 2. This gap D is a distance gap that does not generate plasma.

A ring-shaped electrical insulating member 7 is arranged on the peripheral portion of the holder electrode 2 in a plan view, and extends outwardly in an eaves-like shape to form the holder electrode 2 and the dark space shield 6.
Covers a space above the upper end opening d of the gap D with a slight gap, and further passes over the dark space shield 6,
It extends so as to descend to the outside of the outer surface of the dark space shield upper end portion 61. Therefore, the outer peripheral end 71 of the insulating member 7 is bent to form the upper end 6 of the dark space shield.
It covers the outer surface of 1.

The inner peripheral portion 72 of the ring-shaped eave-shaped insulating member 7
Is installed on the upper surface of the peripheral edge of the insulating film 21 on the electrode 2.
A perforated plate (here, a punching metal) 9 is installed between the outer peripheral surface of the eaves-shaped insulating member 7 and the inner surface of the chamber 1, and this provides ventilation to the extent that vacuum exhaust from the chamber 1 is not hindered. However, it has a plasma shield function.

Above the eaves-shaped insulating member 7, a ring-shaped shade member 8 is arranged in a plan view, which is supported by a shade member holder ring 81, and the holder ring moves up and down the bottom wall 11 of the chamber 1. Rod 82 that penetrates as much as possible
It is connected to. A portion of the rod 82 protruding from the chamber bottom wall 11 to the outside of the chamber 1 is surrounded by an expandable airtight bellows 84 connected to the chamber 1 and the piston cylinder device 83 outside the chamber, and connected to the piston cylinder device 83. There is. Rod 82, holder ring 81
The shade member 8 is driven up and down by the piston cylinder device 83. By this drive, the shade member 8 can move toward and away from the peripheral edge portion s1 of the object S to be processed which is installed on the electrode 2.

The top surface 70 of the above-mentioned eaves-shaped insulating member 7 is used to set an insulating space X between the shade member 8 and the object S to be processed. It is a stopper that determines In the insulating space X obtained by the shade member 8 approaching the workpiece S and contacting the insulating member top surface 70, the member 8 and the workpiece S both plasma the insulating film 21 on the holder electrode 2. It is a metric space that does not come into contact mechanically or thermally within the range where it is not exposed to.

According to the etching apparatus described above, the object S to be processed such as a semiconductor wafer is placed on the insulating film 21 of the holder electrode 2, and the piston cylinder device 8 is continuously operated.
The shade member 8 is lowered by the operation of 3. At the lower limit of the shade member 8, the top surface 70 of the eaves-shaped insulating member 7 is
To the insulating film 2 and the insulating space X is formed between the shade member 8 and the peripheral portion s1 of the workpiece.
The peripheral edge portion of No. 1 which has been exposed so far is cut off from the plasma region P.

Then, the etching gas is introduced from the gas supply unit 4 above the holder electrode 2 under a predetermined vacuum by the operation of the exhaust device 5, and the high frequency power is applied to the electrode 2 from the high frequency power supply 32. Thus, the introduced gas is turned into plasma,
The object S to be processed is subjected to a predetermined etching process under the plasma. During this process, the holder electrode 2 is in contact with the coolant passage 2
By circulating the cooling water from the cooling water circulation device 21b to 1a, the cooling is controlled to a predetermined temperature according to the processing temperature of the object S to be processed, and a DC voltage is applied from the DC power supply 33 to the holder electrode 2. The workpiece S is the holder electrode 2
Is electrostatically adsorbed on the substrate S, and thus the object S to be processed is cooled and controlled to a predetermined temperature from the temperature-controlled holder electrode 2 through the insulating film 21.

Further, the insulating film 21 on the holder electrode 2 is protected from the plasma by covering the peripheral portion s1 of the object S to be processed placed thereon with the shade member 8. At this time, since the shade member 8 covers the peripheral edge portion s1 of the object to be treated through the space X that is mechanically and thermally insulated from the peripheral edge portion s1 of the object to be treated, the shade member exposed to the plasma and heated. Heat conduction does not occur between the member 8 and the object S to be processed as in the conventional clamp type close contact plasma shield, so that the temperature of each part of the object to be processed is made uniform and the plasma processing of each part of the object to be treated is accordingly made. And the shade member 8 does not mechanically contact the peripheral edge portion s1 of the object to be treated, so that the generation of dust at the peripheral edge portion s1 of the object to be treated is prevented, and the good plasma is not affected by the dust. Processing is performed.

Further, a dark space shield 6 is provided outside the peripheral side surface of the holder electrode 2 to prevent generation of plasma in a region where plasma is unnecessary, which faces the peripheral side surface of the holder electrode. Further, when exposed directly to the plasma, the electric field is likely to be concentrated and discharge is likely to occur. Above the opening d of the holder electrode / dark space shield gap D to the outer surface of the dark space shield upper end 61, the peripheral edge of the holder electrode 2 is formed. Since it is covered with the eaves-shaped insulating member 7 extending from the portion, the eaves-shaped insulating member 7 is in a state of enclosing the electric field concentrated portion, which prevents discharge between the holder electrode 2 and the dark space shield 6. ing. Thus, the holder electrode 2 and the dark space shield 6 are safe without fear of damage due to discharge.

Using the apparatus described above, a silicon wafer is placed as the object S to be processed on the insulating film 21 of the holder electrode 2, and a mixed gas of chlorine, boron trichloride, chloroform and nitrogen is introduced as an etching gas. , Processing pressure 20
0mTorr, high frequency power 13.56MHz, 350W
When the etching treatment was carried out at, the temperature of the wafer was substantially uniform in each part.

Next, in the apparatus shown in FIG. 1, the top surface 70 portion which acts as a stopper of the eaves-shaped insulating member 7 is eliminated, and the shade member 8 is pressed and brought into close contact with the peripheral edge of the workpiece on the holder electrode 2. An in-plane temperature uniformity experiment conducted using the apparatus and the apparatus shown in FIG. 1 will be described. This test was conducted under the following conditions.

Object S: Silicon wafer Temperature of holder electrode 2: 70 ° C. Temperature of processing chamber 1: 70 ° C. Etching gas: N ₂ , BCl ₃ , Cl ₂ Processing time: 5 minutes High frequency power: 13.56 MHz, 350 W Voltage applied by DC power source 33: 750 V Process pressure: 200 mTorr Temperature measurement method: Thermo label Insulation space X between the shade member 8 and the object S in the apparatus of FIG. 1 X: 0.5 mm The thermo label is as shown in FIG. In addition, the measurement points A, B, C and D E were provided on the wafer surface.

The results are shown in the following table. Temperature reached at the measurement point of the object to be processed (° C) ABCDE Device 110-116 110-116 110-116 121-127 121-127 Device 116-121 116-121 116-121 116-121 116 of FIG. From these test results, it can be seen that in the apparatus of FIG. 1 according to the present invention, the temperature of the object to be treated is made uniform in each part. In the apparatus, the peripheral edge of the wafer is exposed to plasma and directly clamped by the shade member 8 which is heated, so that the peripheral temperature of the object S to be processed is generally high and nonuniform in each part. is there. Such temperature non-uniformity in the object to be processed becomes a fatal defect in plasma processing, particularly in such etching processing.

Although the dry etching apparatus has been described above as an example, the present invention can be applied to other plasma processing apparatuses (plasma CVD apparatus, etc.).

[0030]

As described above, according to the present invention, an object to be processed is placed via an insulating film on a holder electrode whose temperature can be controlled and which also functions as a holder for the object to be processed. , Introducing a processing gas between the holder electrode and an electrode for the holder electrode and applying high-frequency power between the electrodes to turn the introduced gas into a plasma, and the plasma is applied to the object to be processed under the plasma. A plasma processing apparatus of a type that controls the temperature of the object to be processed while electrostatically adsorbing the object to be processed to the holder electrode by applying a DC voltage to the holder electrode during the process. That is, while preventing the non-uniformity of plasma processing due to the non-uniformity of the temperature in each part of the object to be processed such as when using the conventional clamp type close contact plasma shield, and preventing the generation of dust in the peripheral part of the object to be processed, Holder electrode Possible to provide a plasma processing apparatus capable of protecting the definitive insulating film from the plasma.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a dry etching apparatus which is an embodiment of the present invention.

FIG. 2 is a diagram showing temperature measurement points on an object to be processed in an in-plane temperature uniformity experiment of the object to be processed.

[Explanation of symbols]

 1 Etching chamber 2 Holder electrode (high frequency electrode) 21 Insulating film 21b Cooling water circulation device 21a Refrigerant passage 31 Matching box 32 High frequency power supply 33 DC power supply 34 LC circuit 4 Etching gas supply unit 5 Exhaust device 6 Dark space shield 61 Dark space shield Upper end 7 Eave-shaped insulating member in a ring shape for preventing discharge 71 Bent end of outer circumference of insulating member 70 Top surface (stopper) of insulating member 7 Inner peripheral portion of insulating member 8 Shade member X Insulating space 9 Perforated Plate S Processing object s1 Processing object peripheral edge P Plasma region

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H01L 21/68 H01L 21/68 R H05H 1/46 9216-2G H05H 1/46 A (72) Invention Person Koda Matsuda 47 Umezu Takaune-cho, Ukyo-ku, Kyoto City Nissin Electric Co., Ltd.

Claims (1)

[Claims] 1. An object to be processed is placed on a holder electrode, whose temperature is controllable and also serves as an object holder, with an insulating film interposed between the holder electrode and the electrode for the object. A processing gas is introduced between them to apply a high-frequency power between the electrodes to turn the introduced gas into a plasma, and the object to be processed is subjected to the target processing under the plasma, and during the processing. In a plasma processing apparatus that applies a DC voltage to the holder electrode to electrostatically attract the object to be processed to the holder electrode and controls the temperature of the object to be processed, the object to be processed is not covered with the insulating film. A plasma processing apparatus comprising a shade member for covering a peripheral portion of an object to be processed, which is installed on the insulating film so as to protect the peripheral portion from plasma, while keeping an insulating space therebetween.