JP3028860B2 - Dry etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to a dry etching method.
About the law . More specifically, the present invention relates to a dry etching method capable of performing high-speed, high-selection-rate etching stably with good reproducibility on an object to be processed such as a SiO ₂ layer formed on a substrate such as a silicon wafer.

[0002]

2. Description of the Related Art In recent years, ultra LSIs have become finer in device pattern and larger in diameter of wafers. Is being advanced from a batch type that simultaneously processes the wafers to a single-wafer type that processes one sheet at a time. For example, in a dry etching process, conversion from a conventional batch type to a single-wafer type is performed.

In this case, in order to maintain the same productivity as that obtained by using a batch type dry etching apparatus using a single wafer type dry etching apparatus, the etching rate and the etching selectivity in the single wafer type dry etching apparatus are required. DOO be improved to a large width is required for.

[0004] In order to greatly increase the etch rate, as a single wafer type dry etching apparatus, a magnetic field microwave plasma etching apparatus using an ECR (Electron Cyclotron Resonance) discharge or a magnetron RIE (Reactive A dry etching apparatus using high-density plasma such as an ion etching apparatus has been used.

On the other hand, in the conventional dry etching apparatus, an electrode protection cover is provided on the cathode electrode in order to prevent the cathode electrode from being sputtered during the etching and generating contaminants on the wafer. Using this cathode electrode protective cover as one material, a material that supplies an etchant that etches an object to be processed when sputtered at the time of etching is used. It is intended to improve the etch rate by being supplied. For example, as an electrode protection cover material when etching SiO ₂ , SiO ₂ may be used.
Polytetrafluoroethylene or fluorine resin is used for supplying CFx ⁺ as the _second etchant.

It is conceivable to improve the etch rate by applying such an electrode protection cover to a dry etching apparatus such as a magnetron RIE apparatus using the above-described high-density plasma. FIG. 3 schematically shows a configuration near the object to be processed in this case. In the figure, a permanent magnet 31 that rotates eccentrically is provided above an anode electrode 32 at a ground potential, as indicated by an arrow in the figure. Then, a sample silicon wafer 35 having a SiO ₂ layer formed on its surface is placed on a cathode electrode 36 connected to a 13.56 MHz high frequency power supply 37 via a blocking capacitor 38. The portion of the cathode electrode 36 not covered by the silicon wafer 35 is covered with an electrode protection cover 3 made of polytetrafluoroethylene to protect the cathode electrode 36 from etching.
4 is provided from above the silicon wafer 35 and is fixed by a holding jig 33. Since this electrode protection cover 34 is made of polytetrafluoroethylene, the electrode itself is exposed to plasma or ion beam during etching,
CFx serving as an etchant for silicon wafer 35
Also functions as a sputter target for supplying ⁺ .

At the time of etching, a voltage is applied from a high-frequency power source 37 between the cathode electrode 36 and the anode electrode 32, and a voltage is applied between the anode electrode 32 and the cathode electrode 36.
A high-density plasma 39 is formed so as to cover almost the silicon wafer 35. At this time, since the plasma density can be made uneven by the distribution of the magnetic field intensity, the plasma density on the wafer is made uniform by rotating the permanent magnet 31 eccentrically.

However, when the etching is performed in this manner, the electrode protection cover 34 on the silicon wafer 35 side is always 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 warp to the anode electrode 32 side as shown in FIG. I do. For this reason, the plasma enters below the electrode protection cover 34, and the etching environment of the silicon wafer 35 changes, so that there is a problem that the reproducibility of the etching is reduced. Further, if the silicon wafer 35 is etched many times, the electrode protection cover 34 is significantly deformed, and as a result, the cathode electrode 36
Is exposed, and the cathode electrode 36 itself is etched. For this reason, when the cathode electrode 36 is formed of aluminum which is generally used as an electrode material, aluminum atoms are repelled from the cathode electrode 36, and the aluminum atoms are repelled.
There was also a problem of polluting.

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

Further, in order to improve the etching selectivity in a single-wafer dry etching apparatus, etching is continuously performed in a plurality of processing chambers provided with electrode protection covers of different materials, so that SiO ₂ or the like can be obtained. It has also been proposed to perform both deposition of a reactive reaction species such as carbon or silicon serving as an etching protection layer and supply of an etchant on the surface of a resist patterned on an object surface to be etched. (Japanese Patent Application No. 2-205525).

[0011]

However, even if such an independent cooling means is provided in the electrode protection cover, the deformation of the electrode protection cover gradually progresses. There is a problem that the reproducibility of etching is reduced .

In order to deposit a reactive species such as carbon on the surface of a resist patterned on a wafer in order to perform etching with a high selectivity, a fluorine resin or the like which serves as an etchant supply source during etching is used. It is indispensable that a complicated process in which etching must be performed in a plurality of processing chambers in which an electrode protection cover made of silicon carbide and the like serving as a supply source of the deposition reaction species is provided, respectively. There was also a problem.

The present invention is intended to solve the above-mentioned problems of the prior art, and stably performs high-speed and high-selectivity etching of a SiO ₂ layer or the like formed on a substrate such as a silicon wafer with good reproducibility. It is an object to provide a dry etching method that can be performed.

In order to achieve the above-mentioned object, the present invention provides a method for processing a resist having a patterned resist on its surface.
And location mounting the body on the electrode, the dry etching method for etching the disposed electrode protective cover workpiece on an electrode portion to be processed is not placed, the electrode protection cover and heat resistance member It consists of an etchant supply member,
The heat-resistant member disposed in the portion where the high-density energy during etching is supplied, portions other than at least a high density of energy during d <br/> etching the etchant supply member is supplied In the part to etch the workpiece
When depositing from the heat resistant material to the resist surface
Reactive species are supplied and etched from the etchant supply member.
Dry etching characterized by the supply of a channel
Provide a way .

The dry etching method of the present invention is performed.
A dry etching apparatus is a type of etching apparatus in which an object to be processed is placed on an electrode, and an electrode protection cover is provided on a part of the electrode not covered by the object to be processed to etch the object. The electrode protection cover is made of a specific material. Therefore, as long as the electrode protection cover which characterizes the present invention is used, the magnetron RIE device and the magnetic field microwave
'S Ma etching apparatus or the like are within the scope of the invention. Also,
The present invention, as an object to be processed, Shirikon'u et Ha and GaA
The present invention can be applied to a semiconductor substrate such as an s wafer and various other substrates.

In the present invention, the heat-resistant member is preferably formed of a material which does not substantially thermally deform during etching, for example, an inorganic heat-resistant material, and is further provided on the surface of the object under etching conditions. It is preferable to use a material capable of supplying a deposition reactive species such as carbon or silicon that can be deposited under etching conditions on the patterned resist surface. When the deposition reactive species is carbon or silicon, the heat-resistant member is preferably formed from silicon carbide or amorphous carbon.

The etchant supply member varies depending on the type of the object to be etched and the like. In the case where the object to be processed is a silicon wafer having a SiO ₂ layer formed on the surface, the etchant is supplied under etching conditions. It is preferably formed from a fluororesin that can supply CFx ⁺ , especially polytetrafluoroethylene.

The heat-resistant member and the etchant supply member may be composed of a plurality of materials, respectively.

[0019]

According to the dry etching method of the present invention,
Inside the electrode protection cover to protect the cathode electrode,
Since a portion to which high-density energy is supplied at the time of etching, for example, a portion which is in contact with high-density plasma and exposed to high heat is formed of a heat-resistant material, it is possible to prevent the electrode protection cover from being thermally deformed. Thereby, the reproducibility of etching is improved.

Further, since at least a part of the electrode protection cover other than the part exposed to the high heat is constituted by the etchant supply member capable of supplying the etchant, the etch rate can be improved.

Further, the heat-resistant member is made of a material for supplying a deposition reactive species such as carbon or silicon deposited on the surface of a resist provided on an object to be processed such as a semiconductor substrate under etching conditions. And enables etching with a high selectivity.

In addition, by controlling the ratio of the surface area of the heat-resistant member and the surface area of the etchant supply member, it is possible to optimize the etching conditions for high-speed and high-selection-ratio etching.

[0023]

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

FIG. 1 shows a dry etching method according to the present invention.
It is a top view showing one mode of an electrode protection cover of a cathode electrode in a dry etching device to perform . Here, the etching apparatus main body was the same as the magnetron RIE apparatus described in FIG.

In the case of such a magnetron RIE apparatus, the high-density plasma uses the orientation flat 1
4 and is formed so as to substantially cover the substantially circular silicon wafer 10 having a SiO ₂ layer formed on the surface. Therefore, the inner peripheral portion of the electrode protection cover 11 on the side closer to the silicon wafer 10 is always in contact with the high-density plasma during etching. For this reason, the electrode protection cover 11 of FIG. 1 has a donut shape having a hollow portion adapted to the orientation flat 14 of the silicon wafer 10, and a heat-resistant member 12 made of silicon carbide is disposed on the inner periphery thereof. An etchant supply member 13 made of polyfluoroethylene is provided on the outer peripheral portion. By forming the inner peripheral portion of the electrode protection cover 11 exposed to high heat with the heat resistant member 12 in this manner, the electrode protection cover 1
1 is no longer thermally deformed. Further, the heat-resistant member 12 made of silicon carbide receives ion irradiation during etching and supplies deposition reactive species of carbon or silicon deposited on the surface of the resist on which the pattern is formed on the silicon wafer 10. SiO on 10
Etching with high selectivity of _two layers becomes possible.

The etchant supply member 13 made of polytetrafluoroethylene receives ion irradiation at the time of etching similarly to the heat-resistant member 12, and the silicon wafer 10
Since CFx ^{+ serving} as an etchant for the upper SiO ₂ layer is supplied, an etchant is further supplied in addition to the etchant supplied from the reaction gas, so that high-speed etching can be performed.

The area ratio between the heat-resistant member 12 and the etchant supply member 13 in the surface area of the electrode protection cover 11 is, for example, from the center of the wafer 10 shown in FIG. If the control is performed by changing the distance r to the boundary, it becomes possible to optimize the high-speed and high selectivity etching conditions separately from the control of 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 water passage 24 through which cooling water circulates inside an etchant supply member 23 made of polytetrafluoroethylene. It may be provided. This makes it more reliable to prevent thermal deformation of the electrode protection cover. In the same figure, it is preferable to taper the inner peripheral side of the heat resistant member 22 made of silicon carbide. Thereby, disturbance of the electric field in the inner peripheral portion can be prevented.

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

The material and the like of the electrode protection cover can be appropriately selected according to the etching conditions.

[0031]

Effects of the Invention] According to the dry etching method of the present invention, re <br/> current property that workpiece SiO ₂ layer or the like formed on a substrate such as a silicon wafer to a high-speed and high selectivity etch It can be performed well and stably.

[Brief description of the drawings]

FIG. 1 shows a dry etching method of the present invention.
FIG. 4 is a plan view of one embodiment of an electrode protection cover of a dry etching apparatus to be implemented .

FIG. 2 shows a dry etching method of the present invention.
It is explanatory drawing of another aspect of the electrode protection cover of the dry etching apparatus to implement .

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

FIG. 4 is an explanatory diagram showing a state where 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

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065

Claims (3)

(57) [Claims] A resist having a pattern formed on a surface thereof;
The object to be processed and location mounting on the electrode, the dry etching method for etching the disposed electrode protective cover workpiece on an electrode portion to be processed is not placed, the electrode protection cover heat to consist of a sexual member and etchant supply member, is disposed a heat resistant member in a portion where the density of the energy at the time of etching is supplied, a high density of energy is supplied to the etchant supply member during etching disposed on at least a portion other than a portion that, et of the object
During the etching process, the heat-resistant member
Deposition reactive species is supplied, and etchant supply member
A dry etching method, wherein an etchant is supplied from the substrate . 2. The dry etching according to claim 1, wherein the electrode protection cover has a donut shape, the heat-resistant member is disposed on an inner peripheral portion, and the etchant supply member is disposed on an outer peripheral portion. How . 3. The dry etching method according to claim 2, wherein silicon carbide and / or amorphous carbon is used as said heat-resistant member, and fluorine resin is used as said etchant supply member.