JP3220631B2 - Plasma processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing method and apparatus used for manufacturing semiconductors and the like, and more particularly to a plasma processing method and apparatus capable of generating high-density plasma at a high vacuum degree and suitable for plasma processing of a laminated film containing a noble metal. And a plasma processing method and apparatus.

[0002]

2. Description of the Related Art In a manufacturing process of a non-volatile memory using a ferroelectric thin film, which has attracted attention as a next-generation semiconductor memory and has been rapidly developed, in particular, dry etching of platinum (Pt) used as an electrode material. Regarding the above, there is a demand for a plasma processing method and apparatus capable of ensuring high in-plane uniformity and a good shape after processing and realizing high productivity.

As a conventional general plasma processing apparatus, a parallel plate type plasma processing apparatus (RIE plasma processing apparatus) used in a low vacuum, or an inductively coupled plasma processing apparatus (1) capable of obtaining a high plasma density in a high vacuum. (MSC plasma processing apparatus), an ECR plasma processing apparatus constituted by a microwave and a magnetic field, and capable of obtaining a high plasma density in a high vacuum.

FIG. 4 shows a general configuration of a parallel plate type plasma processing apparatus. In FIG. 4, reference numeral 21 denotes a vacuum vessel, in which the upper and lower openings of a cylindrical body 22 are sealed by an upper wall body 23 and a lower wall body 24. Etc. are provided. Reference numeral 25 denotes an upper electrode disposed on the inner surface of the upper wall member 23, reference numeral 26 denotes a lower electrode disposed at a position facing the upper electrode 25 on the inner surface of the lower wall member 24, and reference numeral 27 denotes a substrate mounted on the lower electrode 26. , 28 are high frequency power supplies.

[0005] In the above-described configuration, the gas is evacuated while introducing an appropriate gas into the vacuum vessel 21, and the lower electrode 26 is supplied by the high frequency power supply 28 while maintaining the inside of the vacuum vessel 21 at an appropriate pressure.
By applying a high-frequency voltage to the substrate 27, plasma is generated in the vacuum vessel 21, and the plasma processing can be performed on the substrate 27.

FIG. 5 shows an apparatus configuration of an inductively coupled plasma processing apparatus (hereinafter referred to as an MSC plasma processing apparatus) using multiple spirally formed electromagnetic induction coils. The details are described in Japanese Patent Application No. 6-219323.

In FIG. 5, reference numeral 31 denotes a vacuum vessel, in which upper and lower openings of a cylindrical body 32 are sealed by a dielectric plate 33 as an upper wall surface and a lower wall surface member 34, and if necessary, a cylindrical shape. A supply / exhaust hole or the like is provided on a side surface of the body 32. 35 is a multiple spiral electromagnetic induction coil whose projected area on the dielectric plate 33 is about 5%, 36 is an electrode arranged on the inner surface of the lower wall 34, 37 is a substrate mounted on the electrode 36, 38 Is a first high frequency power supply, and 39 is a second high frequency power supply.

In the above-described structure, a high-frequency voltage is applied to the electromagnetic induction coil 35 by the first high-frequency power supply 38 while evacuating while introducing an appropriate gas into the vacuum vessel 31 and maintaining an appropriate pressure in the vacuum vessel 31. By doing so, plasma is generated in the vacuum vessel 31 and plasma processing can be performed on the substrate 37. At this time, the electrode 36
When a high-frequency voltage is also applied, the ion energy reaching the substrate 37 can be controlled.

[0009]

However, when platinum (Pt) is etched by a parallel plate type plasma processing apparatus for generating plasma at a low vacuum shown in FIG. 4, the plasma density is low and the optimum etching rate is low. Can not get.

When platinum (Pt) is etched by an ECR plasma processing apparatus constituted by a microwave and a magnetic field, a plasma having a relatively high vacuum and a high density can be obtained. Etching can be performed, and the etching speed is excellent. However, there is a problem that it is difficult to obtain in-plane uniformity of the etching of the workpiece, and a product generated at the time of etching accumulates in the vacuum vessel, thereby causing contamination of the workpiece.

Further, when platinum (Pt) is etched by the MSC plasma processing apparatus shown in FIG. 5, good etching can be performed by fine processing or the like as in the case of the ECR plasma processing apparatus, and the etching rate can be increased. Also excellent in nature. Further, since the plasma density can be easily made uniform by adjusting the shape of the coil, the in-plane uniformity of the etching of the workpiece is also good. However, there is a problem that products generated at the time of etching accumulate in the vacuum vessel and cause contamination of the workpiece.

In view of the above problems, the present invention can generate a high-density plasma of inductive coupling in a high vacuum, achieve a good processing speed, and achieve a good plasma distribution with an optimum plasma distribution. An object of the present invention is to provide a plasma processing method and apparatus capable of obtaining in-plane uniformity of processing and reducing the amount of products deposited on a dielectric plate or a vacuum vessel wall.

[0013]

According to a first aspect of the present invention, there is provided a plasma processing method in which a substrate is placed on an electrode in a vacuum vessel, and exhaust is performed while introducing gas into the vacuum vessel. A plasma processing method for applying a high-frequency voltage to an electromagnetic induction coil disposed along a dielectric plate facing a substrate while maintaining an appropriate pressure to generate plasma in a vacuum vessel and process the substrate. The projected area on the dielectric plate is 50% or more and 85% of the total area of the dielectric plate.
It is characterized in that less than two planar coils are used.

Preferably, the dielectric plate and the wall surface of the vacuum vessel are kept at 150 ° C. or more and less than 200 ° C., and the substrate on which the laminated film containing a noble metal is formed is processed.

The plasma processing apparatus according to the second aspect of the present invention includes a vacuum vessel having a gas inlet and an exhaust port, an electrode for mounting a substrate in the vacuum vessel, and a vacuum vessel at a position facing the electrode. In a plasma processing apparatus provided with a dielectric plate provided as a wall surface and an electromagnetic induction coil provided on the dielectric plate, the electromagnetic induction coil has a projection area on the dielectric plate of 50% of the total area of the dielectric plate. % Or less and less than 85%.

Preferably, the electromagnetic induction coil is in the form of multiple spirals and includes means for controlling the temperature of the dielectric plate and the wall surface of the vacuum vessel.

According to the above configuration of the present invention, a good etching rate can be obtained even when a laminated film containing a noble metal such as platinum (Pt) is etched by inductively coupled high-vacuum high-density plasma. Since the projected area of the electromagnetic induction coil with respect to the dielectric plate is 50% or more and less than 85% of the total area of the dielectric plate, a large negative self-bias is generated in the dielectric plate by the high frequency voltage applied to the coil. Sputtering occurs on the surface of the dielectric plate due to the negative electric field, so that products that are likely to adhere to the dielectric plate can be reduced.

Further, the temperature of the dielectric plate and the vacuum vessel is set to 1
By controlling the temperature to 50 ° C. or more and less than 200 ° C., it is possible to significantly reduce products deposited on the side surfaces of the dielectric plate and the vacuum vessel.

Further, the in-plane uniformity of the etching can be obtained with the optimum plasma distribution by the multiple spiral coil configuration.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the plasma processing method and apparatus of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a vacuum vessel,
The upper and lower openings are sealed by a dielectric plate 3 serving as an upper wall surface and a lower wall member 4, and a supply / exhaust hole or the like is provided on the side surface of the cylindrical body 2 as necessary. Reference numeral 5 denotes a multiple spiral and planar electromagnetic induction coil having a width of 25 mm and a number of coils of 4 so that the area projected onto the dielectric plate 3 becomes 80%. 6 is a heater unit for heating the dielectric plate 3, and 7 is a heater unit for heating the wall surface of the vacuum vessel 1.
Reference numeral 8 denotes an electrode arranged on the inner surface of the lower wall body 4, reference numeral 10 denotes a substrate mounted on the electrode 8, reference numeral 11 denotes a first high-frequency power supply, and reference numeral 12 denotes a second high-frequency power supply.

In the above-described configuration, a high-frequency voltage is applied to the electromagnetic induction coil 5 by the first high-frequency power supply 11 while evacuating while introducing an appropriate gas into the vacuum vessel 1 and maintaining an appropriate pressure in the vacuum vessel 1. By doing so, plasma is generated in the vacuum chamber 1 and plasma processing can be performed on the substrate 10. At this time, when a high-frequency voltage is also applied to the electrode 8 from the second high-frequency power supply 12, the ion energy reaching the substrate 10 can be controlled.

Next, the operation will be described in detail. Vacuum container 1
The chamber is evacuated while introducing several sccm of Cl ₂ gas and O ₂ gas into the vacuum chamber, and 450 W from the first high frequency power supply 11 while maintaining the inside of the vacuum vessel 1 at a pressure of 8 mTorr.
When power of 400 W is supplied from the high frequency power supply 12, plasma is generated in the vacuum vessel 1. Si in this plasma
Substrate 1 in which platinum (Pt) was deposited on a wafer at 3000 °
0 and etched. At this time, the temperature of the dielectric plate 3 and the wall surface of the vacuum vessel 1 is room temperature (20 ° C.).

Table 1 shows the above embodiment of the present invention and a conventional example (R
Conventional examples of each type of IE, ECR, and MSC are shown. 3) shows a comparison between the etching rate of platinum (Pt) and in-plane uniformity in the plasma processing apparatus shown in FIG.

[0025]

[Table 1]

From Table 1, it can be seen that the plasma processing apparatus according to the present embodiment is capable of producing a high-density plasma with high vacuum in a conventional example.
It can be seen that an etching rate similar to that of the C plasma processing apparatus or the ECR plasma processing apparatus can be obtained. In addition, the in-plane uniformity of the etching is easy to adjust the plasma distribution.
Good results are obtained with the SC plasma processing apparatus and the apparatus of the present embodiment.

Next, the deposition amount and distribution of products adhering to the dielectric plate and the wall surface of the vacuum vessel in the present embodiment and the MSC plasma processing apparatus were investigated. Under the same etching conditions as above, platinum (Pt) was etched at 9000 ° (three wafers). FIG. 2 shows the result of the investigation. From this result, it can be seen that the amount of products deposited on the dielectric plate and the wall surface of the vacuum vessel is smaller in the plasma processing apparatus of the present embodiment than in the conventional MSC plasma processing apparatus.

It is believed that this can be explained by the following mechanism. When a noble metal such as platinum (Pt) is etched, the effect of physical etching by radical components generated in the plasma is larger than that by a chemical reaction by ions generated in the plasma, and the product is chemically etched. Noble metal atoms are the main component rather than the substance that has reacted. For this reason, in the conventional plasma processing apparatus, the amount of the product adhering to the upper dielectric plate and the side wall of the vacuum vessel is more than the rate of the product being volatilized and exhausted from the vacuum vessel. On the other hand, in the plasma processing apparatus of the present embodiment, a large negative self-bias is generated in the dielectric plate due to the high-frequency voltage applied to the wide coil, and the ions are accelerated by the negative electric field to cause sputtering on the surface of the dielectric plate. Happens. Therefore, it is possible to reduce the amount of products deposited on the dielectric plate as described above.

The coil area is 50 times the projected area on the dielectric plate.
% Or less, the sputtering effect cannot be obtained because the negative self-bias generated in the dielectric plate is small. Also,
If it exceeds 85%, the reflected power increases, the power efficiency may decrease, and in some cases, no discharge occurs.

Next, the dependence of the deposition amount of the product on the wall surface of the dielectric plate and the vacuum vessel of the present embodiment and the temperature was investigated. Under the same etching conditions as above, the temperatures of the dielectric plate and the wall surface of the vacuum vessel were set to 20 ° C, 75 ° C,
Under three conditions of 150 ° C., platinum (Pt) was etched at 9000 ° (three wafers) under each condition, and the deposited film thickness was measured. The results are shown in FIG. From FIG. 3, it can be seen that heating the wall surface of the dielectric plate and the vacuum vessel to 150 ° C. or more has an effect of reducing the amount of deposited products. However, if the temperature is higher than 200 ° C., adverse effects will be caused.

As can be seen from the above results, in the present embodiment, the deposition amount of the product adhering to the dielectric plate and the wall surface of the vacuum vessel is smaller than that of the conventional example at an etching rate substantially equal to that of the conventional example. Good results were obtained.

[0032]

According to the plasma processing method and apparatus of the present invention, as is apparent from the above description, a good processing speed can be obtained by the inductively coupled high-vacuum high-density plasma. Is less than or equal to 50% and less than 85% of the total area of the dielectric plate, a large negative self-bias is generated in the dielectric plate by the high frequency voltage applied to the coil, and the negative electric field Sputtering occurs on the surface of the body plate, and products that are likely to adhere to the dielectric plate can be reduced.

Further, the temperature of the dielectric plate and the vacuum vessel is set to 1
By controlling the temperature to 50 ° C. or more and less than 200 ° C., it is possible to significantly reduce products deposited on the side surfaces of the dielectric plate and the vacuum vessel.

In particular, it is effective when a laminated film containing a noble metal such as platinum is subjected to plasma treatment.

Further, the in-plane uniformity of the excellent processing can be obtained by the optimum plasma distribution by the multiple spiral coil configuration.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of a plasma processing apparatus according to the present invention, partially cut away.

FIG. 2 is a comparison diagram of the amount of deposition and distribution of products adhering to a dielectric plate and a wall surface of a vacuum vessel in the embodiment and a conventional example.

FIG. 3 is a diagram showing a dependency between a deposition amount of a product adhered to a dielectric plate and a wall surface of a vacuum vessel and temperature in the same embodiment.

FIG. 4 is a perspective view showing a schematic configuration of a conventional plasma processing apparatus.

FIG. 5 is a perspective view showing a schematic configuration of another conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 3 Dielectric plate 5 Electromagnetic induction coil 6 Heater unit 7 Heater unit 8 Electrode 10 Substrate 11 1st high frequency power supply

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-227878 (JP, A) JP-A 8-138888 (JP, A) JP-A 8-83696 (JP, A) JP-A 9-98 232282 (JP, A) JP-A-9-237776 (JP, A) JP-A-9-143366 (JP, A) JP-A-7-211702 (JP, A) JP-A-7-161488 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 C23F 4/00 H01L 21/205 H05H 1/46

Claims (6)

(57) [Claims] 1. A substrate is placed on an electrode in a vacuum vessel, exhaust is performed while gas is introduced into the vacuum vessel, and along a dielectric plate facing the substrate while maintaining the inside of the vacuum vessel at an appropriate pressure. In a plasma processing method in which a high-frequency voltage is applied to an electromagnetic induction coil disposed to generate plasma in a vacuum vessel to process a substrate, a projected area of the dielectric plate as an electromagnetic induction coil is the entire area of the dielectric plate. 50% to 85% of
A plasma processing method characterized by using a coil having a planar shape of less than. 2. The dielectric plate and the wall surface of the vacuum vessel are set at 150 °.
The plasma processing method according to claim 1, wherein the temperature is maintained at not less than C and less than 200 ° C. 3. The plasma processing method according to claim 1, wherein the substrate on which the laminated film containing a noble metal is formed is processed. 4. A vacuum vessel having a gas inlet and an exhaust port, an electrode for mounting a substrate in the vacuum vessel, a dielectric plate provided as a vacuum vessel wall at a position facing the electrode, In a plasma processing apparatus having an electromagnetic induction coil installed on a body plate, a projected area of the electromagnetic induction coil with respect to the dielectric plate is 50% or more of the total area of the dielectric plate.
A plasma processing apparatus comprising less than 5% of a planar coil. 5. The plasma processing apparatus according to claim 4, wherein the electromagnetic induction coil has a multiple spiral shape. 6. The plasma processing apparatus according to claim 4, further comprising means for controlling the temperature of the dielectric plate and the wall surface of the vacuum vessel.