JPH11158662A - Plasma treatment and plasma treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly execute the shower-like gas supply of a plasma treatment apparatus. SOLUTION: This plasma treatment apparatus executes the plasma treatment of a wafer 6 placed on a lower electrode 3 by impressing high-frequency electric power between the lower electrode 3 and upper electrode 4 disposed in a process chamber 1 from a high-frequency power source 13 and forming the plasma 14 of the treating gas 9a. The upper electrode 4 is formed with a branch pipeline 5 which is uniform in the conductance of the plural branch routes from a gas supply hole 41a at one point of the center of a cooling plate 41 of a supply source to plural release ends 4d by stacking plural pipeline plates 42 to 4n formed with branch grooves 4a and through-holes 4b under the cooling plate 41. The shower-like treating gases 9a are uniformly supplied into the process chamber 1 through this branch pipeline 5, by which the distribution state of the plasma 14 in the upper part of the wafer 6 is made uniform and the uniform plasma treatment result is obtd. The distribution of the conductance is intentionally controlled by changing the length/bore of the branch grooves 4a and through-holes 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing technique, and more particularly to a technique which is effective when applied to a plasma processing for supplying a processing gas in a shower state.

[0002]

2. Description of the Related Art For example, in a plasma processing apparatus such as a plasma etching apparatus, a high-frequency electric power is supplied between opposed electrode plates while a gas is supplied into a vacuum vessel and the vacuum vessel is evacuated to a certain pressure. Apply and generate plasma. Generally, a semiconductor wafer is mounted on one of the opposed electrode plates, and gas is supplied from the other side to perform plasma processing on the semiconductor wafer.

In this case, for example, “Industrial Research Committee Co., Ltd., published on November 25, 1994,“ Electronic Materials ”199
As described in the literature such as 4 years separate printing, P44 to P51, etc., in order to supply gas uniformly over a wide range,
A method has been adopted in which several hundred small holes are provided in a shower shape on the counter electrode plate on the gas supply side, and gas is supplied from the small holes.

[0004]

In such a conventional technique, gas is first introduced from one point on the upstream side of the electrode plate,
Finally, the water is supplied into the vacuum vessel from several hundred micro holes provided in the electrode plate in a shower shape. In order to uniformly supply gas into the vacuum chamber from the shower-shaped gas hole, a space serving as a gas reservoir is provided at a position immediately before the upstream side in the electrode plate as illustrated in FIG. 5, for example. Depending on the difference between the conductance of the gas hole and the conductance of the gas hole (the conductance of the space / the conductance of the gas hole), a uniform supply can be expected to some extent. However, it is difficult with this method to make the relationship between the gas reservoir space and the individual gas holes all the same and to make the conductance constant, so that there is a technical problem that it is difficult to supply gas uniformly from the individual gas holes. is there.

In addition, since the counter electrode plate is exposed to a high temperature from the plasma, it is general to perform temperature control for the purpose of cooling. However, a gas reservoir space is formed upstream of the shower-like gas hole. Therefore, most of the inside of the electrode is a space, and the heat transfer area is small, and it is difficult to sufficiently control the temperature of the electrode plate itself. For this reason, the temperature of the electrode plate increases, and other technical problems such as thermal expansion of the electrode plate are also concerned.

An object of the present invention is to provide a plasma processing technique capable of arbitrarily controlling a distribution of a supply amount of a processing gas supplied in a shower shape.

Another object of the present invention is to provide a plasma processing technique capable of improving the uniformity of plasma processing performed by supplying a processing gas in a shower shape.

It is another object of the present invention to provide a plasma processing technique capable of accurately controlling the temperature of an electrode for supplying a processing gas in a shower shape and a gas supply means.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0010]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

The present invention is directed to a plasma processing method for supplying a processing gas to an object to be processed housed in a processing chamber, converting the processing gas into plasma, and performing a desired plasma processing on the object to be processed. The plasma processing is performed by supplying a processing gas in the form of a shower through a plurality of branch conduits whose conductance from the supply source to a plurality of discharge ends can be controlled uniformly or independently.

More specifically, as an example, a processing gas is introduced from one location on the upstream side of the electrode plate, and is supplied into the vacuum vessel in a shower form from a number of minute holes provided on the surface facing the workpiece. In such a configuration, the following means are used.

That is, instead of the conventional gas reservoir space, a branch pipe having a common specification such as a cross-sectional area and a length and having a constant conductance in the flow path is formed. In this case, a large number of micro holes are opened on the facing surface of the object to be processed. Then, the processing gas is supplied to the branch pipe line, and the processing gas is uniformly dispersed in a shower shape through a large number of discharge ends (micro holes) so as to uniformly supply the processing gas.

[0014] This makes it possible to uniformly perform the plasma processing on the object to be processed. Furthermore, the electrode has a solid structure except for the branch conduit, and has no excessively large space, so that heat conductivity is improved.For example, it is possible to flow a heat medium through a flow path provided inside the electrode. It is possible to accurately perform temperature adjustment by using the above method.

[0015] If necessary, the distribution of conductance of the plurality of branch conduits is set arbitrarily.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of the configuration of a plasma etching apparatus which is an embodiment of the plasma processing method and the plasma processing apparatus of the present invention, and FIG. 2 is an assembly showing an example of the configuration of the electrodes. FIG. 3 and FIG. 3 are conceptual diagrams showing an example of a branched state of a branch pipe provided in the electrode.
FIG. 3 is an explanatory diagram showing a comparison between the electrode of the present embodiment and a conventional technology.

The flow rate of the processing gas 9 a supplied from the gas cylinder 9 into the processing chamber 1 formed by the vacuum vessel 2 is adjusted by the mass flow controller 8, introduced through the gas supply system 7, and simultaneously evacuated by the vacuum pump 12. And
A pressure adjusting valve 11 is provided in the exhaust system 10 to perform pressure adjustment. In this state, the lower electrode 3 facing in the vertical direction
A high frequency power is applied between the first electrode and the upper electrode 4 by a high frequency power supply 13 to generate plasma 14, and the wafer 6 placed on the lower electrode 3 is etched.

A heat medium passage 3a is provided inside the lower electrode 3, and a heat medium 16a of a predetermined temperature supplied from the lower electrode temperature controller 16 is caused to flow through the heat medium passage 3a. Temperature control is performed. The temperature of the upper electrode 4 is adjusted by a heating medium 15a supplied from the upper electrode temperature controller 15 as described later.

In the case of this embodiment, as illustrated in FIG. 2, the upper electrode 4 is composed of a cooling plate 41 and a plurality of conduit plates 42 to.
It has a multilayer structure in which 4n are air-tightly stacked. That is, the uppermost cooling plate 41 is formed so as to surround the gas supply hole 41a penetrating the central portion and the heat medium flow passage 41b through which the heat medium 15a flows.
And a connection hole 41c connected to the upper electrode temperature controller 15
Are formed.

Each of the lower conduit plates 42 to 4n is provided with a branch groove 4a radially branched in a cross shape, and is formed at the tip of the branch groove 4a so as to penetrate the conduit plate. A through hole 4b is formed. The through hole 4b of each conduit plate is formed so as to overlap the position of the branch center 4c of the branch groove 4a of the conduit plate immediately below. However, the branch center 4c of the branch groove 4a of the uppermost pipeline plate 42 among the pipeline plates 42 to 4n.
Is one gas supply hole 4 provided in the center of the cooling plate 41.
1a. Further, the plurality of through holes 4b of the lowermost conduit plate 4n function as discharge ends 4d for ejecting the processing gas 9a in a shower shape.

That is, in the first-stage conduit plate 42, one gas supply hole 41a of the cooling plate 41 is branched into four paths by one cross-shaped branch groove 4a, and the second-stage conduit plate In 43,
The four cross-shaped branch grooves 4a branch into 16 paths, and the third-stage conduit plate 44 further branches into sixteen paths with sixteen cross-shaped branch grooves 4a to form a fourth path. In the conduit plate 45, the branch is further branched into 256 by 64 branch grooves 4a. At this time, in each of the conduit plates 42 to 4n, the shape (width / depth / length) of the cross-shaped branch groove 4a is the same, and the diameter of the through hole 4b connecting the upper and lower conduit plates is the same. To

As a result, the branch grooves 4a and the through holes 4b of the plurality of pipeline plates 42 to 4n stacked in an airtight manner communicate with each other, as shown in FIG. 3, from the gas supply holes 41a of the supply source. A branch pipe line 5 having the same conduit length and cross-sectional area (distribution of change in cross-sectional area) up to the discharge end 4d and having uniform conductance is formed.

That is, the processing gas 9a introduced from one location of the gas supply hole 41a at the center of the cooling plate 41 is
The operation of dividing into four by the 2 to 4n branch grooves 4a is, for example, 4 operations.
1 (in the example of FIGS. 1 and 2 of this embodiment, two times are illustrated for simplicity of illustration) (that is, 4 times).
Pipe plates 42 to 4n), and finally, the gas supply holes 41
a is equally divided into 256 emission ends 4d.

The processing accuracy of the branch groove 4a and the through hole 4b is, for example, ± 0.3 to 0.3 when the length from the tip to the tip has a distribution of 20 mm to 200 mm. Processed with a dimensional error of .5mm, branch groove 4a
And the diameter of the through hole 4b is, for example, 1 mm × 1 mm to 1.
It has been confirmed that in the case of a distribution of 5 mm to 1.5 mm, sufficient uniformity of conductance can be obtained with a processing error of about ± 0.1 mm.

The distribution of the processing gas 9a supplied from the upper electrode 4 into the processing chamber 1 is intended by changing the shape or the number of branches of the branch groove 4a or changing the diameter of the communicating hole 4b. Can be easily changed.

As described above, according to the plasma etching apparatus of the present embodiment, cooling plate 41
A branch pipe 5 having a uniform conductance of a plurality of branch paths from one gas supply hole 41a to a plurality of discharge ends 4d.
, The processing gas 9a is supplied to the processing chamber 1 in the form of a shower, so that a theoretically uniform gas supply becomes possible.

As a result, the uniformity of the distribution of the plasma 14 formed from the processing gas 9a supplied between the wafer 6 on the lower electrode 3 and the upper electrode 4 is improved, and the etching of the wafer 6 by the plasma 14 is improved. The etching can be performed uniformly, a uniform etching result can be obtained, the dimensional accuracy of a circuit pattern (not shown) formed on the wafer 6 by the etching is improved, and a semiconductor device (not shown) formed on the wafer 6 is formed. Yield and performance are improved.

Further, by intentionally changing the conductance (adjusted by the flow path cross-sectional area and flow path length) of the plurality of branch conduits, the supply state and distribution of the processing gas 9a from the upper electrode 4 to the processing chamber 1 are changed. Can be controlled, for example, fine control of the plasma 14 according to the process conditions and the like can be performed. For example, the conductance of the plurality of emission ends 4d on the outer peripheral portion of the upper electrode 4 can be set to be larger than the conductance of the plurality of inner emission ends 4d.

Further, in the case of the present embodiment, the plurality of conduit plates 42 to 4n constituting the upper electrode 4 have a conventional structure in which a large gas reservoir space is formed as illustrated in FIG. The contact area, that is, the heat conduction area is larger than that of
Temperature can be more accurately controlled by the heat from the heat medium 15a flowing through the upper electrode 4, and it is possible to prevent trouble such as thermal deformation of the upper electrode 4 due to overheating or the like.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say, there is.

For example, in the above-described embodiment, the case where the upper electrode is used as the gas supply means has been exemplified. However, the present invention includes a gas supply means provided with a branch pipe separately from the electrode. The plasma processing is not limited to plasma etching, and can be widely applied to general plasma processing such as plasma CVD.

In the above description, the case where the invention made mainly by the inventor is applied to the plasma etching step in the manufacturing process of the semiconductor device which is the background of the application has been described as an example. It can be widely applied to general process technology used.

[0034]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

According to the plasma processing method of the present invention, there is obtained an effect that the distribution of the supply amount of the processing gas supplied in the form of a shower can be arbitrarily controlled.

Further, according to the plasma processing method of the present invention, it is possible to improve the uniformity of the plasma processing performed by supplying the processing gas in the form of a shower.

Further, according to the plasma processing method of the present invention, it is possible to obtain an effect that the temperature of the electrode and the gas supply means for supplying the processing gas in the form of a shower can be accurately controlled.

According to the plasma processing apparatus of the present invention, the distribution of the processing gas supplied in the form of a shower can be arbitrarily controlled.

Further, according to the plasma processing apparatus of the present invention, it is possible to improve the uniformity of the plasma processing performed by supplying the processing gas in the form of a shower.

Further, according to the plasma processing apparatus of the present invention, there is obtained an effect that the temperature of the electrode for supplying the processing gas in the form of a shower or the gas supply means can be accurately controlled.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of a plasma etching apparatus which is an embodiment of a plasma processing method and a plasma processing apparatus according to the present invention.

FIG. 2 is an assembly diagram showing an example of a configuration of an electrode of a plasma etching apparatus which is an embodiment of the plasma processing method and the plasma processing apparatus according to the present invention.

FIG. 3 is a conceptual diagram showing an example of a branched state of a branch pipe provided in an electrode of a plasma etching apparatus which is an embodiment of the plasma processing method and the plasma processing apparatus according to the present invention.

FIG. 4 is an explanatory diagram showing an electrode according to an embodiment of the present invention and a conventional technique in comparison with each other.

FIG. 5 is an explanatory view showing an example of a structure inside an electrode plate of a possible conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing chamber 2 Vacuum container 3 Lower electrode 3a Heat medium passage 4 Upper electrode 41 Cooling plate 41a Gas supply hole 41b Heat medium flow passage 41c Connection hole 42-4n Pipe plate 4a Branch groove 4b Through hole 4c Branch center 4d Release end 5 Branch line 6 Wafer 7 Gas supply system 8 Mass flow controller (gas flow controller) 9 Gas cylinder 9a Processing gas 10 Exhaust system 11 Pressure control valve 12 Vacuum pump 13 High frequency power supply 14 Plasma 15 Upper electrode temperature controller 15a Heat medium 16 Lower electrode Temperature controller 16a Heat medium

Claims (8)

[Claims] 1. A plasma processing method for supplying a processing gas to an object to be processed housed in a processing chamber, converting the processing gas into plasma, and performing a desired plasma processing on the object to be processed. A plasma processing method, wherein the plasma processing is performed by supplying the processing gas in the form of a shower through a plurality of branch conduits whose conductance from a supply source of the processing gas to a plurality of discharge ends can be independently controlled. 2. The plasma processing method according to claim 1, wherein the branch pipe is formed inside an electrode member for applying a high-frequency energy for converting the processing gas into plasma, and the branch member is formed on the processing target of the electrode member. A plasma processing method, characterized in that the processing gas is supplied in a shower form from the discharge end of the branch pipe opened to the facing surface. 3. The plasma processing method according to claim 2, wherein the electrode member includes a plurality of plate members including a radial groove engraved on a main surface and a through hole formed at a tip end of the groove. By radially stacking the airtight so that the center of the groove overlaps and communicates with the through hole of the upper plate material, the branch pipe is formed by the groove and the through hole communicating with each other in a plurality of the plate materials. A plasma processing method, wherein a path is configured. 4. The plasma processing method according to claim 2, wherein a medium passage through which a heat medium flows is formed in a region of the electrode member that does not interfere with the branch conduit, and a desired temperature is formed in the medium passage. A temperature control of said electrode member by flowing said heat medium. 5. A processing chamber accommodating an object to be processed, gas supply means for supplying a processing gas into the processing chamber, and high-frequency energy for converting the processing gas in the processing chamber into plasma. A plasma processing apparatus comprising: an electrode member; and an exhaust unit that exhausts the inside of the processing chamber, wherein the gas supply unit independently controls conductance from a source of the processing gas to a plurality of discharge ends. A plasma processing apparatus, comprising: a plurality of possible branch conduits; wherein the processing gas is supplied in a shower form from a plurality of the discharge ends. 6. The plasma processing apparatus according to claim 5, wherein the electrode member has a structure also serving as the gas supply means, and the discharge of the branch conduit opened on a surface of the electrode member facing the workpiece. A plasma processing apparatus, wherein the processing gas is supplied in a shower shape from an end. 7. The plasma processing apparatus according to claim 5, wherein the gas supply means or the electrode member comprises:
A plurality of plate members including a radial groove engraved on the main surface and a through hole drilled at the tip of the groove, the center of the radial groove is overlapped with the through hole of the upper plate member. A plasma processing apparatus, wherein the branch pipe is constituted by airtightly stacked to communicate with each other, and the groove and the through hole communicating with each other of a plurality of the plate members. 8. The plasma processing apparatus according to claim 5, wherein the gas supply means or the electrode member has a medium passage through which a heat medium flows in a region not interfering with the branch conduit. A plasma processing apparatus, wherein a temperature control of the gas supply means or the electrode member is performed by flowing a heat medium at a desired temperature in the medium passage.