JPH04356920A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To provide a dry etching apparatus which realizes high speed etching with a high selection ratio of a processing object such as SiO2 layer, etc., formed on a substrate such as a silicon wafer. CONSTITUTION:A dry etching apparatus is of such a type as placing a processing object on an electrode and arranging an electrode protection cover to an electrode portion not covered with the processing object to conduct the etching of the processing object. The electrode protection cover 11 is formed of a heat resistant member 12 and an etchant supply member 13 for supplying etchant to conduct etching for the processing object 10. This heat resistant member is arranged to a part where high density energy is supplied at the time of etching and the etchant supply member 13 is disposed at least in a portion other than the region where high density energy is supplied at the time of etching. In the case where the dry etching apparatus main body is a magnetron RIE apparatus, such electrode protection cover 11 is formed in the shape of a doughnut, the heat resistant member 12 is arranged at the internal circumference thereof, while the etchant supply member 13 at the external circumference thereof.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus. More specifically, the present invention relates to a dry etching apparatus that can stably perform high-speed, high-selectivity etching on an object to be processed, such as an SiO2 layer formed on a substrate such as a silicon wafer, with good reproducibility.

0002

[Background Art] In recent years, ultra-LSI device patterns have become finer and wafers have become larger in diameter. The transition from batch-type processing, in which wafers are processed simultaneously, to single-wafer processing, in which wafers are processed one by one, is underway. For example, even in dry etching processes, the conventional batch type is being converted to a single wafer type.

In this case, in order to maintain the same productivity using a single-wafer type dry etching apparatus as when using a batch-type dry etching apparatus, it is necessary to adjust the etch rate and etching selectivity of the single-wafer type dry etching apparatus. It is necessary to greatly improve this.

In order to significantly improve the etch rate, single-wafer type dry etching apparatuses include a magnetic field μ-wave plasma etching apparatus using ECR (electron cyclotron resonance) discharge and a magnetron RIE (reactive etching apparatus) using magnetron discharge. Dry etching devices that utilize high-density plasma, such as ion etching) devices, have come into use.

On the other hand, in conventional dry etching equipment, an electrode protection cover is provided over the cathode electrode in order to prevent the cathode electrode from being sputtered and generating contaminants on the wafer during etching. This cathode electrode protection cover is used as a material that supplies an etchant that etches the target object when sputtered during etching. It has been attempted to improve the etch rate by supplying the etchant. For example, SiO2 can be used as an electrode protection cover material when etching SiO2.
Fluororesins such as polytetrafluoroethylene are used to supply CFx+, which serves as an etchant.

It is conceivable to apply such an electrode protection cover to a dry etching apparatus such as the above-mentioned magnetron RIE apparatus that utilizes high-density plasma to improve the etch rate. FIG. 3 schematically shows the configuration near the object to be processed in this case. In the figure, a permanent magnet 31 that rotates eccentrically as indicated by an arrow in the figure is provided above an anode electrode 32 that is at ground potential. A silicon wafer 35 as a sample having a SiO2 layer formed on its surface is placed on a cathode electrode 36 connected to a 13.56 MHz high frequency power source 37 via a blocking capacitor 38. An electrode protection cover 3 made of polytetrafluoroethylene is placed on the portion of the cathode electrode 36 that is not covered by the silicon wafer 35 in order to protect the cathode electrode 36 from etching.
4 is disposed on the silicon wafer 35 and fixed with a holding jig 33. Since this electrode protection cover 34 is made of polytetrafluoroethylene, it is exposed to plasma or ion beam during etching.
CFx as an etchant for the silicon wafer 35
It also functions as a sputter target that supplies +.

During etching, a voltage is applied between the cathode electrode 36 and the anode electrode 32 from the high frequency power source 37, and between the anode electrode 32 and the cathode electrode 36,
A high-density plasma 39 is formed so as to substantially cover the silicon wafer 35. At this time, the distribution of the magnetic field strength causes uneven plasma density, so the permanent magnet 31 is eccentrically rotated to make the plasma density on the wafer uniform.

However, when etching is performed in this manner, the electrode protection cover 34 on the side of the silicon wafer 35 is constantly in contact with the plasma 39. Therefore, the portion of the electrode protection cover 34 that is in contact with the plasma 39 is deformed so as to be warped toward the anode electrode 32, as shown in FIG. do. For this reason, the plasma enters the lower part of the electrode protection cover 34 and the etching environment of the silicon wafer 35 changes, resulting in a problem that the reproducibility of etching is reduced. Furthermore, if the silicon wafer 35 is etched many times, the electrode protection cover 34 will be significantly deformed, and as a result, the cathode electrode 36
is exposed, and the cathode electrode 36 itself is etched. Therefore, when the cathode electrode 36 is made of aluminum, which is generally used as an electrode material, aluminum atoms are ejected from the cathode electrode 36 and are transferred to the silicon wafer 35.
There was also the problem of contamination.

In order to solve these problems, the present inventor previously proposed providing an independent cooling means on the electrode protection cover (Japanese Patent Application No. 1-315727).

Furthermore, in order to improve the etching selectivity in a single-wafer type dry etching apparatus, etching of SiO2, etc. It has also been proposed to both deposit a deposition reactive species such as carbon or silicon to serve as an etching protection layer on the surface of a resist patterned on the target surface, and supply an etchant ( (Patent Application No. 205525/1999).

[0011]

[Problem to be Solved by the Invention] However, even if the electrode protection cover is provided with an independent cooling means in this way, the deformation of the electrode protection cover will progress gradually, so if etching is performed a large number of times, Again, there was a problem that the reproducibility of etching deteriorated. Another problem was that it was technically difficult to process and form an independent cooling means on the electrode protection cover made of fluororesin.

In addition, in order to perform etching with a high selectivity, and to deposit reactive species such as carbon on the surface of the resist patterned on the wafer, it is necessary to use a fluororesin or the like that serves as an etchant supply source during etching. It is said that a complicated process is essential in that etching must be performed in multiple processing chambers each equipped with an electrode protection cover made of silicon carbide, etc., which serves as a source of deposition reactive species. There were also problems.

[0013] The present invention is an attempt to solve the problems of the prior art as described above, and is to stably perform high-speed, high-selectivity etching of a SiO2 layer formed on a substrate such as a silicon wafer with good reproducibility. The purpose of the present invention is to provide a dry etching device that can perform the following steps.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present invention places an object to be processed on an electrode, and places an electrode protective cover on the part of the electrode where the object to be processed is not placed. In a dry etching apparatus that etches an object to be processed by disposing a Provided is a dry etching apparatus characterized in that the etchant supply member is disposed in at least a portion other than a portion to which high-density energy is supplied during etching.

The dry etching apparatus of the present invention is of a type in which an object to be processed is placed on an electrode, and an electrode protection cover is provided on a portion of the electrode that is not covered by the object to be processed. In an etching apparatus, the electrode protection cover is made of a specific material. Therefore,
The scope of the present invention also includes conventionally used magnetron RIE devices, magnetic field microwave plasma etching devices, etc., as long as they use the electrode protection cover that characterizes the present invention. Further, the present invention can be applied to semiconductor substrates such as silicon wafers and GaAs wafers, and other various substrates as objects to be processed.

In the present invention, the heat-resistant member is preferably formed from a material that is not substantially thermally deformed during etching, such as an inorganic heat-resistant material, and furthermore, the heat-resistant member is preferably formed from a material that is not substantially thermally deformed during etching, and furthermore, the heat-resistant member is It is preferably formed from a material capable of providing a deposition reactive species such as carbon or silicon that can be deposited under etching conditions on the patterned resist surface. When the deposition reaction species is carbon or silicon, the heat-resistant member is preferably formed from silicon carbide or amorphous carbon.

Although the etchant supply member differs depending on the type of object to be etched, if the object to be processed is a silicon wafer with a SiO2 layer formed on the surface, CFx + It is preferable to use a fluororesin, which is a material capable of supplying the following properties, and in particular polytetrafluoroethylene.

Note that the heat-resistant member and the etchant supply member may each be made of a plurality of materials.

[0019]

[Operation] The dry etching apparatus of the present invention provides a portion of the electrode protection cover for protecting the cathode electrode to which high-density energy is supplied during etching, such as a portion that comes into contact with high-density plasma and is exposed to high heat. Since the electrode protection cover is made of a heat-resistant material, it is possible to prevent the electrode protection cover from being deformed by heat. This improves etching reproducibility.

Furthermore, since at least a portion of the electrode protective cover other than the portion exposed to high heat is constituted by an etchant supply member capable of supplying an etchant, it is possible to improve the etch rate.

Furthermore, by constructing the heat-resistant member from a material that supplies deposition reactive species such as carbon and silicon that are deposited under etching conditions on the surface of a resist provided on an object to be processed such as a semiconductor substrate. , which enables etching with high selectivity.

In addition, by controlling the ratio of the surface areas of the heat-resistant member and the etchant supply member, it is possible to optimize the etching conditions for etching at high speed and with a high selectivity.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. However, the invention is not limited to these examples.

FIG. 1 is a plan view showing one embodiment of an electrode protection cover for a cathode electrode of a dry etching apparatus according to the present invention. Here, the main body of the etching apparatus was similar to the magnetron RIE apparatus described with reference to FIG.

In the case of such a magnetron RIE device, the high-density plasma is placed on the orientation flat 14.
It is formed to substantially cover a substantially circular silicon wafer 10 having a SiO2 layer formed on its surface. Therefore,
The inner peripheral portion of the electrode protection cover 11 on the side closer to the silicon wafer 10 is constantly in contact with high-density plasma during etching. From this, the electrode protection cover 11 in FIG.
has a donut-like shape with a hollow part that matches the orientation flat 14 of the silicon wafer 10, and a heat-resistant member 12 made of silicon carbide is disposed on the inner circumference, and a polyfluoroethylene member is disposed on the outer circumference. An etchant supply member 13 is provided. thus,
By configuring the inner peripheral portion of the electrode protection cover 11 exposed to high heat with the heat-resistant member 12, the electrode protection cover 11 is prevented from being thermally deformed. Furthermore, the heat-resistant member 12 made of silicon carbide receives ion irradiation during etching and supplies carbon and silicon deposition reaction species that precipitate on the patterned resist surface on the silicon wafer 10. It becomes possible to etch the SiO2 layer on 10 with a high selectivity.

Furthermore, the polytetrafluoroethylene etchant supply member 13 is subjected to ion irradiation during etching, similar to the heat-resistant member 12, and the silicon wafer 10
Since CFx+, which serves as an etchant for the upper SiO2 layer, is supplied, in addition to the etchant supplied from the reaction gas, an additional etchant is supplied, making it possible to perform high-speed etching.

Note that the area ratio of the heat resistant member 12 and the etchant supply member 13 to the surface area of the electrode protection cover 11 is determined, for example, from the center of the wafer 10 as shown in FIG. By controlling by changing the distance r to the boundary, it becomes possible to optimize the high-speed, high-selectivity etching conditions in addition to controlling the reaction gas.

As shown in FIG. 2, the electrode protection cover 21 of the present invention is provided with an independent cooling means, for example, a cooling channel 24 through which cooling water circulates inside an etchant supply member 23 made of polytetrafluoroethylene. It may be provided. This further ensures prevention of thermal deformation of the electrode protection cover. Further, in the figure, it is preferable that the inner peripheral side of the heat-resistant member 22 made of silicon carbide is tapered. This makes it possible to prevent disturbances in the electric field in the inner circumference.

The electrode protection cover that characterizes the present invention has been described in detail above, but the shape of the electrode cover,
Whether the heat-resistant member is disposed inside or outside the electrode protection cover can be changed as appropriate depending on the structure of the dry etching apparatus main body to be used. For example, in a magnetic field microwave plasma etching system that applies a high-frequency voltage to the wafer, if the electrode on the outer periphery of the wafer is grounded, high-energy ions will be incident on the outer periphery of the wafer. A heat-resistant member is provided around the outer periphery of the electrode protection cover.

Furthermore, the material of the electrode protection cover can be appropriately selected depending on the etching conditions.

[0031]

[Effects of the Invention] According to the dry etching apparatus of the present invention, objects to be processed such as SiO2 layers formed on substrates such as silicon wafers can be etched at high speed and with high selectivity in a stable manner with good reproducibility. Can be done.

[Brief explanation of drawings]

FIG. 1 is a plan view of one embodiment of an electrode protection cover that characterizes the dry etching apparatus of the present invention.

FIG. 2 is an explanatory diagram of another embodiment of the electrode protection cover that characterizes the dry etching apparatus of the present invention.

FIG. 3 is an explanatory diagram of a conventional dry etching apparatus.

FIG. 4 is an explanatory diagram showing how an electrode protection cover is thermally deformed in a conventional dry etching apparatus.

[Explanation of symbols]

10, 35 Object to be processed 11, 21, 34 Electrode protection cover 12, 22 Heat resistant member 13, 23 Etchant supply member 14 Orientation flat 24 Cooling water channel 32 Anode electrode 36 Cathode electrode 39 High density plasma

Claims (4)

[Claims] Claim 1: A dry etching apparatus in which a workpiece is placed on an electrode, and an electrode protection cover is disposed on a portion of the electrode where the workpiece is not placed, and the workpiece is etched. The protective cover includes a heat-resistant member and an etchant supply member, the heat-resistant member is disposed in a portion where high-density energy is supplied during etching, and the etchant supply member supplies high-density energy during etching. A dry etching apparatus characterized in that the dry etching apparatus is disposed at least in a part other than the part to which the dry etching apparatus is supplied. 2. The electrode protection cover according to claim 1, wherein the electrode protection cover has a donut-like shape, the heat-resistant member is disposed on the inner circumference, and the etchant supply member is disposed on the outer circumference. Dry etching equipment. 3. The dry etching apparatus according to claim 1, wherein the heat-resistant member is made of a material that supplies a deposition reaction species to a resist patterned on the surface of the object to be processed during etching. . 4. The dry etching apparatus according to claim 3, wherein the heat-resistant member is made of silicon carbide and/or amorphous carbon, and the etchant supply member is made of fluororesin.