JP3259422B2 - Electrode used in plasma processing apparatus and plasma processing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of devices using semiconductors such as thin film transistors and various sensors utilizing semiconductors, solar cells, and the like. Plasma CVD for etching the formed film according to a predetermined pattern
The present invention relates to an apparatus, a plasma processing apparatus such as a plasma etching apparatus, and an electrode for generating plasma used in the apparatus.

[0002]

2. Description of the Related Art Various types of plasma CVD apparatuses are known. As a representative example, a parallel plate type plasma CVD apparatus shown in FIG. 4 will be described. This apparatus has a vacuum vessel 1 in which an electrode 2 also serving as a substrate holder for installing a film-forming substrate S1 and an electrode 2 Are provided.

[0003] The electrode 2 is usually a ground electrode.
A heater 21 for heating the substrate S1 mounted thereon to a film forming temperature is additionally provided. In order to heat the substrate S1 by radiant heat, the heater 21 may be separately arranged. Electrode 3
Is a power application electrode for applying high-frequency power or DC power to the film-forming gas introduced between the electrode 2 and turning it into a plasma. In the example shown, a high-frequency power supply 32 is connected via a matching box 31. I have.

In the example shown in the figure, the electrode 3 is formed of a flat electrode plate, in which a number of gas supply holes 33 having a diameter of about 0.5 mm are formed. From the substrate S1 on the electrode 2 in a direction perpendicular or substantially perpendicular to the substrate S1 and between the two electrodes. Such a configuration is suitable for forming a film on a wide-area substrate.

An exhaust pump 52 is connected to the vacuum vessel 1 via an on-off valve 51 via a pipe, and a gas supply section 4 is connected to the gas nozzle section 34 via a pipe. One or more mass flow controllers 421, 422,... And on-off valves 431, 4
Include gas sources 441, 442,... For supplying a predetermined amount of film-forming gas via.

[0006] The side and back surfaces of the nozzle portion 34 are surrounded by a ground electrode 40 provided at a certain interval from the nozzle for preventing the plasma from flowing around. According to the parallel plate type plasma CVD apparatus, the film formation target substrate S
1 is installed on the electrode 2 in the vacuum vessel 1, the inside of the vessel 1 is maintained at a predetermined film forming vacuum degree by opening the valve 51 and operating the exhaust pump 52, and a film forming gas is supplied from the gas supply unit 4. be introduced. Further, a high-frequency voltage is applied to the high-frequency electrode 3 from the power supply 32, and the introduced gas is turned into plasma, and a desired film is formed on the surface of the substrate S1 under this plasma.

[0007] Various types of plasma etching apparatuses are also known. A parallel plate type etching apparatus shown in FIG. 5 will be described as a typical example. This apparatus also includes a vacuum vessel 10, in which an electrode 20 also serving as a substrate holder on which a substrate S2 on which a film to be etched is formed and an electrode 20 are provided. An electrode 30 is provided opposite to the electrode 20.

The electrode 20 is used as a power application electrode for applying a high frequency power or a DC power to the etching gas introduced between the electrode 30 and the plasma to form a plasma. Connected to the high frequency power supply 202. The electrode 30 is a ground electrode, includes a flat electrode plate, and has a plurality of gas supply holes 301 having a diameter of about 0.5 mm formed therein. Gas supplied from the gas nozzle unit 302 is supplied from each hole to the substrate S2 on the electrode 20. In a direction perpendicular or substantially perpendicular to the electrode and between the electrodes.

An exhaust pump 72 is connected to the vacuum vessel 10 via an on-off valve 71, and a gas supply section 6 is connected to the gas nozzle section 302. The gas supply unit 6 includes one or more mass flow controllers 621, 622,.
., Which supply a required amount of etching gas via 632.

The side and rear portions of the nozzle portion 302 are surrounded by a ground electrode 60 for preventing the plasma from flowing around, which is arranged at a fixed distance from the nozzle portion. According to this etching apparatus, the substrate S2 to be etched is
The container 10 is placed on the high-frequency electrode 20, and the inside of the container 10 is maintained at a predetermined etching vacuum degree by opening the valve 71 and operating the exhaust pump 72, and an etching gas is introduced from the gas supply unit 6. Further, a high-frequency voltage is applied to the electrode 20 from the high-frequency power supply 202, and the introduced gas is turned into plasma, and the film on the substrate S2 is etched under the plasma. The electrode 20 may be cooled by a water cooling device 200 or the like as necessary.

[0011]

However, in a plasma CVD apparatus, fine particles formed by a gas phase reaction in plasma near a substrate surface on a substrate holder electrode adhere to a film formed on the substrate surface, There is a problem that the film quality is deteriorated by being mixed into the inside. Fine particles are formed by a gas phase reaction, and a film having a high possibility of growing large, for example, an amorphous silicon (a-Si) film is formed from silane (SiH ₄ ) and hydrogen (H ₂ ).
An amorphous silicon nitride (a-SiN) film is formed from silane and ammonia (NH ₃ ), and an amorphous silicon oxide (a-SiO ₂ ) film is formed from silane and dinitrogen monoxide (nitrous oxide) (N ₂ O). In such film formation, the size of the fine particles adhering to or mixed into the film formed on the substrate surface is larger than the film thickness of the formed film, and as a result, the film is an insulating film In such a case, if the cleaning treatment is performed after the film formation, there is a problem in that the fine particles become pinholes and insulation failure occurs, and when the film is a semiconductor film, the semiconductor characteristics deteriorate.

Also, in the plasma etching apparatus, similarly, there is a problem that fine particles are formed by a gas phase reaction in plasma and adhere to the surface to be etched.
For example, in the case where a wiring pattern is formed by etching, such fine particles cause deterioration in patterning accuracy, and may cause disconnection in the formation of fine lines.

Accordingly, the present invention provides an electrode and a plasma processing apparatus, which are used in a plasma processing apparatus capable of suppressing particles generated by a gas phase reaction in plasma from adhering to a substrate to be processed. It is an object to provide a device. The term “adhesion” here and “adhesion” which will be described later in the “effect of the invention” means, in film formation, direct adhesion to the substrate surface, adhesion to the film to be formed, In the case of etching,
It is a concept indicating direct attachment to the substrate surface, attachment or mixing to a film to be etched, and the like.

[0014]

Means for Solving the Problems The present inventor has conducted research on a means for effectively suppressing the adhesion of fine particles to a substrate, and as a result, the electrode is directed to a plasma region of an electrode arranged opposite to a substrate to be processed. If irregularities are formed on the surface,
Since the same potential surface formed along the entire electrode surface falls into the recesses, these recesses become electric field drop portions, and usually,
The negatively charged fine particles are attracted to the portion where the potential difference is large and gathered there, and are trapped there.In addition, all or a part of these recesses are inclined with respect to the plasma potential surface in the direction in which the fine particles are to be excluded. If it has, it can guide the fine particles in the direction of its elimination, and furthermore, if the fine particle elimination direction is aligned with the exhaust direction from the vacuum vessel for plasma processing, the elimination of the fine particles from the electrode will be easier, and Even in the case where the recess is not inclined with respect to the plasma potential surface in the direction in which the fine particles are to be eliminated in the concave portion, the fine particle eliminating effect can be obtained simply by aligning all or a part of the concave portion in the exhaust direction from the vacuum vessel. I found something.

The electrode of the present invention for solving the above-mentioned problem is based on this attention, and is an electrode used for a plasma processing apparatus, which is disposed opposite to a substrate to be processed, and has an electrode surface facing a plasma region. in the gas phase reaction more to provide the electric field drop section to collect fine particles that occur in the
The groove extends in the direction in which the fine particles are to be removed.
And each groove is formed in the longitudinal direction of the groove.
Along the direction to remove the fine particles along
Form gradually deeper to be inclined with respect to the plasma potential plane
Characterized in that was. In addition, the plasma processing apparatus of the present invention for solving the above-mentioned problems is characterized in that a processing gas introduced into a vacuum vessel provided with an exhaust device is turned into plasma under a predetermined degree of vacuum by operation of the exhaust device, A plasma processing apparatus for performing a target process on a substrate to be processed under the condition that the electrode is provided, and the longitudinal direction of the concave groove of the electrode is provided.
The electrode and the exhaust device are arranged so that the directions are aligned with the exhaust direction of the exhaust device.

[0016]

[0017]

According to the electrode of the present invention, the fine particles generated by the gas phase reaction in the plasma, particularly the fine particles generated in the vicinity of the electrode, have a plurality of grooves which provide an electric field drop portion on the surface of the electrode.
It is formed so as to extend in the direction of removing fine particles.
In each of the grooves, the fine particles are formed along the longitudinal direction of the groove.
Tilt to the plasma potential plane in the direction to be eliminated
Because it is progressively deeper as gathered their grooves, are captured therein, it can be guided to microparticles eliminated along the concave groove. According to the plasma processing apparatus of the present invention, the fine particles trapped in the groove of the electrode have the groove extending in the direction of removing the particle.
Since the longitudinal direction of the concave groove, which is the direction of removing the fine particles, is aligned with the exhaust direction in the vacuum vessel, the gas is smoothly discharged out of the vessel together with the exhaust gas.

Thus, the adhesion of the fine particles to the substrate is suppressed as compared with the related art.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a plasma CVD apparatus having an electrode 8 for applying power for plasma generation according to an embodiment of the present invention. This plasma CVD apparatus employs an electrode 8 in place of the high-frequency electrode 3 in the conventional apparatus shown in FIG. 4, and this electrode is also used as a high-frequency electrode.
It is connected to the. Other points are the same as those of the apparatus shown in FIG. 4, and the whole film forming operation is also the same. Parts that are the same as the parts in the apparatus of FIG. 4 are given the same reference numerals.

FIG. 2 shows the electrode 8 in each case.
(A) is a bottom view showing the electrode surface directed to the plasma region, (B) is a right side view, (C) is a left side view,
FIG. 3D is a cross-sectional view taken along line XX of FIG. 3A, and FIG. ,
(B) is a diagram showing a potential inclination state in the groove longitudinal direction.

The electrode 8 is formed in the shape of a plate as a whole. The electrode surface 80 facing the plasma region has a direction from the right side to the left side in FIG. A number of grooves 81 are formed in parallel in the same direction as a, and a number of gas supply holes 83 are formed at substantially equal intervals in each of the ridges 82 adjacent thereto. Each gas supply hole 83 is a hole having a diameter of about 0.5 mm, and a film-forming gas is discharged from the holes in a direction perpendicular or substantially perpendicular to the ground electrode 2 and entirely between the electrodes 2 and 3. It has become. The lower surface of each ridge 82, in other words, the gas outlet of the gas supply hole 83 is located at the same plane position so as to obtain uniformity of the formed film, and the substrate S1 on the electrode 2
The plane is substantially parallel to the surface.

Each groove 81 is formed gradually deeper from the right side to the left side in FIG. 1, that is, in the exhaust direction a in the container 1 by the exhaust pump 52 (upward in FIG. 1). According to the plasma processing apparatus described above, the film formation target substrate S1 is set on the electrode 2 in the vacuum vessel 1,
The inside of the container 1 is maintained at a predetermined film forming vacuum degree by opening the valve 51 and operating the exhaust pump 52, and the film forming gas supplied from the gas supply unit 4 through the gas nozzle unit 34 is supplied to the high frequency electrode 8. The gas is introduced between the electrodes 8 and 2 through the gas supply hole 83.
Further, a high-frequency voltage is applied to the high-frequency electrode 8 from the power supply 32, and the introduced gas is turned into plasma, and a desired film is formed on the surface of the substrate S1 under this plasma.

During the film formation, fine particles are generated by a gas phase reaction in the plasma. Particularly, since the gas density is relatively high and the temperature is relatively low near the electrode 8, a large amount of fine particles are generated in that portion. P is usually negatively charged, but the fine particles P generated in this manner, particularly the fine particles P generated near the electrode 8, have a large number of grooves 81 that provide an electric field drop portion on the surface of the electrode 8. In the direction intersecting with the longitudinal direction of the groove 81, as shown in FIG. 3A, it moves to the higher potential (higher to the + side) according to the electric field, gathers in the groove 81, and is captured there. Is done.

Further, the grooves 81 are formed gradually deeper in the direction of removing particles, which coincides with the exhaust direction a. In other words, since the grooves are inclined in the direction of removing particles with respect to the plasma potential surface, these grooves are formed. Fine particles P captured by
Is based on the potential gradient shown in FIG.
It is guided in the direction of removing fine particles, and is smoothly discharged together with the exhaust from the container 1. Thus, adhesion of the fine particles P to the substrate S1 is suppressed as compared with the related art.

The groove 8 for providing the electric field drop portion of the electrode 8
The size, degree of inclination, etc. of 1 are not particularly limited, and are not limited to those of the above-described embodiment as long as an electric field gradient capable of capturing fine particles and a potential inclination capable of transport can be obtained. There is no particular limitation on the number of grooves 81, but it is preferable that the number be such that the fine particles can be collected from the entire surface of the electrode 8 as much as possible.

[0026]

With the apparatus of FIG. 1 described above, a-S
An example in which an i: H film is formed will be described. Film forming conditions Substrate: 5 inch silicon wafer Gas: SiH ₄ 100 sccm H ₂ 400 sccm Film forming temperature: 230 ° C. Film forming gas pressure: 0.4 Torr Applied power: 200 W Electrode size: 360 mm × 360 mm □ Irregularities on the surface of electrode 8 82: 21 mm in width Groove 81: 8 mm in width Inclination angle 2.5 ° Gas supply hole 83: 204 in 0.5 mm in diameter Electrode interval: 45 mm (distance between the surface of the convex portion of the electrode 8 and the surface of the substrate) The number of the attached fine particles in the a-Si: H film was 0.3 μm or more, and was 5 or less.

When the conventional high-frequency electrode 3 was employed, the number was about 50 under the same conditions as the other conditions. Although the plasma CVD apparatus has been described above, an electrode according to the present invention, such as the electrode 8 having a plurality of concave grooves for providing the electric field lowering portion, may be used instead of the ground electrode 30 of the plasma etching apparatus of FIG. Similarly, the adhesion of the fine particles to the substrate is suppressed as compared with the related art.

[0029]

As described above, according to the present invention, a fine particle generated by a gas phase reaction in plasma can be prevented from adhering to a substrate to be processed. An electrode and a plasma processing apparatus to be arranged can be provided.

In particular, according to the electrode of the present invention, it is possible to easily replace the conventional electrode and use it, and it is possible to suppress the adhesion of fine particles to the substrate at low cost and without having to particularly change the film forming conditions and etching conditions.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of a plasma CVD apparatus employing an electrode according to an embodiment of the present invention.

2A and 2B show electrodes for applying power for plasma generation in the apparatus of FIG. 1, wherein FIG. 2A is a bottom view showing an electrode surface directed to a plasma region, FIG. 2B is a right side view, (C) is a left side view, (D) is a view XX of (A).
It is sectional drawing which follows a line.

3A is a diagram showing a potential state in a direction perpendicular to a longitudinal direction of a groove on the electrode surface in FIG. 2, and FIG. 3B is a diagram showing a potential inclination state in a groove longitudinal direction.

FIG. 4 is a schematic configuration diagram of an example of a conventional plasma CVD apparatus.

FIG. 5 is a schematic configuration diagram of an example of a conventional plasma etching apparatus.

[Explanation of symbols]

 1, 10 Vacuum container 2, 30 Ground electrode 20, 3 High frequency electrode 201, 31 Matching box 202, 32 High frequency power supply 21 Heater 51, 71 Open / close valve 52, 72 Exhaust pump 4, 6 Gas supply unit 8 High frequency electrode 80 Surface 81 Groove on the surface of electrode 8 82 Protrusion on the surface of electrode 8 83 Gas supply hole S1 Substrate to be deposited S2 Substrate to be etched P Particle a Particle removal direction (exhaust direction)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 C23C 16/50 H01L 21/3065

Claims (2)

(57) [Claims] 1. A used in the plasma processing apparatus, an electrode disposed opposite to the processing target substrate, the electrode surface directed to the plasma region, the electric field drop section Ru collect particles generated in the gas phase reaction in the plasma Multiple grooves to provide
Formed to extend in the direction to remove the fine particles
Along with each groove along the longitudinal direction of the groove.
Plasmids lead to the direction of trying to eliminate the fine particles
An electrode characterized in that it is formed gradually deeper so as to be inclined with respect to the electric potential plane . 2. A process gas, which is introduced into a vacuum vessel provided with an exhaust device, is turned into plasma under a predetermined degree of vacuum by operation of the exhaust device. Claims 1. A plasma processing apparatus for performing a process, comprising: an electrode according to claim 1;
The plasma processing apparatus, wherein the electrode and the exhaust device are arranged so that a longitudinal direction of the groove is aligned with an exhaust direction of the exhaust device.