JP2002009048A - Focus ring for plasma processing equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent reduction in yield due to erosion of a focus ring and generation of particles, and to reduce the manufacturing cost of a semiconductor device. SOLUTION: When a substrate 7 is placed on an electrode 6 in a processing chamber 1 into which a reactive gas is introduced, and plasma is generated by the electrode 6, the substrate 7 is processed so as to surround the periphery of the substrate 7. A focus ring of a plasma processing apparatus installed in the processing member, the first member having a surface facing the inside of the processing chamber substantially in parallel with the surface of the substrate and having a surface close to the periphery of the substrate;
0, and a second member 11 disposed below the first member 10 to support the first member 10. Thus, when the surface is deteriorated, the entire focus ring is not replaced as in the related art, but the first generation of particles is remarkable.
Only the member 10 can be replaced, and the operating cost of the plasma processing apparatus such as dry etching and the manufacturing cost of the semiconductor device can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus ring used for improving the uniformity of plasma processing, particularly dry etching, in a semiconductor device manufacturing process, and more particularly to a plasma processing apparatus used in a halogen-based gas plasma atmosphere. This is related to the focus ring.

[0002]

2. Description of the Related Art Conventionally, dry etching using plasma has been frequently used for processing semiconductor substrates. In the dry etching treatment using plasma, a reactive gas is introduced into a chamber under reduced pressure, and the gas is excited using a high frequency, a magnetic field, or the like to etch an object to be processed on a semiconductor substrate.
Therefore, in order to ensure processing uniformity, the distribution of plasma density in a region including a semiconductor substrate in a processing chamber is a very important factor in a dry etching apparatus.

FIG. 3 is a sectional view of a conventional parallel plate type dry etching apparatus. In FIG. 3, 1 is a processing chamber for performing dry etching, 2 is an exhaust port for evacuating the processing chamber 1, 3 is a gas inlet for introducing a dry etching gas into the processing chamber 1, 4 is a gas inlet 3. A large number of holes are formed on the flat electrode at a gas outlet for injecting the entered process gas into the processing chamber 1 (shower head method). Reference numeral 5 denotes an anode electrode, 6 denotes a cathode electrode to which a high frequency is applied, 7 denotes a substrate to be etched, 8 denotes a focus ring, and 9 denotes a high-frequency power supply.

The operation of the dry etching apparatus configured as described above will be described below. The substrate 7 is transported and installed on the cathode electrode 6 by a transporter (not shown) mounted outside the dry etching processing chamber. Next, the inside of the processing chamber 1 is evacuated from the exhaust port 2 until a predetermined degree of vacuum is reached, a reactive gas required for etching is introduced from the gas inlet port 3,
And is diffused into the processing chamber 1. After the gas flow and pressure are stabilized, a voltage is applied to the cathode electrode 6 from the high frequency power supply 9 to generate reactive gas plasma. A focus ring 8 is generally used as one of means for making gas plasma uniform in a region including the semiconductor substrate, and the substrate 7 provided on the cathode electrode 6 is etched using the focus ring 8.

In a plasma processing apparatus such as a dry etching apparatus as shown in FIG. 3, there is a problem in that the distribution of the reactive process gas or the uniformity of the concentration thereof is not always sufficient over the entire surface of the semiconductor substrate 7. This is remarkable at the periphery of the substrate. The non-uniformity of the reactive process gas causes the processing rate to be non-uniform and variable over the substrate. In such a case, the flow of the reactive process gas is corrected by using the focus ring 8 around the substrate,
Enhancing uniformity has been undertaken.

[0006]

FIG. 4 shows a conventional focus ring 20, which is often made of an alumina material. In a focus ring made of an alumina material, when a halogen-based gas plasma composed of F, Cl, or Br is used as an etching gas, halogen ions or radicals that are components that actually contribute to the etching of a semiconductor substrate are used. Alumina particles are eroded by this, and an aluminum halide based film is formed on the focus ring surface. This phenomenon occurs at a portion of the focus ring along a circumference close to the semiconductor substrate.

[0007] In such a state, the film is peeled off by the attack of ions, becomes aluminum halide particles, and adheres to the substrate 7. In a recent etching process having a strong anisotropy, a material to be etched of a semiconductor substrate is subjected to an etching process using particles as a mask, so that an etching residue is left on the substrate, which causes a reduction in the yield of semiconductor devices.

For example, when etching a silicon nitride film on a semiconductor substrate with CF ₄ = 80 sccm, a pressure of 40 Pa, and a high frequency of 200 W / cm, the focus ring 8 is also etched. At this time, fluorine (F), which is an etching component of the gas plasma, erodes the alumina particles of the focus ring to form an Al-F-based film on the surface.
The film is peeled off by the attack of the ions present in the gas plasma, and becomes Al-F-based particles and adheres to the substrate 7. Since the attached particles are subjected to the etching process as a mask, the etching remains and the yield is reduced.

As a countermeasure, it is necessary to increase the frequency of replacement of the focus ring whose surface has been deteriorated in order to prevent a decrease in yield due to Al-F type particles generated from the focus ring. However, there is a disadvantage that the production cost is increased.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent a focus ring provided around a semiconductor substrate of a plasma processing apparatus such as a dry etching apparatus from being eroded and a yield from being reduced due to generation of particles, thereby reducing a manufacturing cost of a semiconductor device. It is to provide a focus ring for the processing device.

[0011]

According to a first aspect of the present invention, there is provided a focus ring for a plasma processing apparatus, wherein a substrate is placed on an electrode in a processing chamber into which a reactive gas is introduced. A focus ring of a plasma processing apparatus installed so as to surround a peripheral portion of the substrate when plasma is generated by the electrode and processing the substrate, wherein the processing ring is substantially parallel to a surface of the substrate. A first member having a surface facing the interior of the room and adjacent to the peripheral portion of the substrate, and a second member disposed below the first member to support the first member.

As described above, the first surface having the surface facing the inside of the processing chamber substantially parallel to the surface of the substrate and being close to the peripheral portion of the substrate is provided.
And the second member disposed below the first member to support the first member. Therefore, when the surface is deteriorated, the entire focus ring is not replaced as in the conventional case, but the particle Only the first member having a remarkable generation source can be replaced, and the operation cost of a plasma processing apparatus such as dry etching and the manufacturing cost of a semiconductor device can be suppressed.

According to a second aspect of the present invention, in the plasma processing apparatus, the first member of the focus ring is made of a material containing Si. As described above, since the first member of the focus ring is made of a material containing Si, the focus ring is excellent in erosion resistance to gas plasma.

According to a third aspect of the present invention, in the focus ring of the plasma processing apparatus according to the first or second aspect, the reactive gas contains halogen. As described above, since the reactive gas contains halogen, plasma containing halogen is generated to contribute to the etching of the semiconductor substrate, and even if particles are generated by erosion of the focus ring, only the first member needs to be replaced. Can be dealt with.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram of a plasma processing apparatus using a focus ring according to an embodiment of the present invention.

As shown in FIG. 1, a substrate 7 is placed on an electrode 6 in a processing chamber 1 into which a reactive gas is introduced, and plasma is generated by the electrode 6 to process the substrate 7. A focus ring 12 is provided so as to surround the periphery of the substrate 7. The focus ring 12
A first member having a surface facing the processing chamber substantially parallel to the surface of the substrate and proximate to the periphery of the substrate; and a second member disposed below the first member for supporting the first member. And a member 11. In FIG. 1, the same members as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 2A is a plan view of the focus ring according to the embodiment of the present invention, and FIG. 2B is a sectional view of the focus ring in a separated state. The focus ring is not an integral structure as in the related art, but has at least a two-body structure. In this case, as shown in FIG. 2, the member is located in a peripheral portion of the semiconductor where ion bombardment from gas plasma is remarkable during etching, and Al-F-based particles are generated during etching with a fluorine-based gas. It comprises a generator (first member) 10 and a pedestal (second member) 11 that covers the side surface of the cathode electrode 6.

In the focus ring for dry etching according to this embodiment, the generator 10 which is eroded by the halogen plasma and generates Al-F-based particles as described above.
And a focus ring having a two-body structure composed of other pedestal portions 11.
Generating part 10 and pedestal part 1 for positioning
1 positioning unevenness 10a, 1
1a are processed separately, and have a structure that can eliminate problems such as displacement during joining. Holes 10b and 11b for inserting the electrode 6 are provided at the center of the generator 10 and the pedestal 11, respectively. It is sufficient for these two members to place 10 on 11 and it is not necessary to fix them.

By using the two-body focus ring, only the generating portion 10 that generates remarkable dust such as Al-F-based particles can be used as a replacement member. The cost is lower than replacing the entire device, and an increase in device manufacturing cost can be suppressed.

As described above, the constituent materials are eroded by the ions or radicals of the halogen at a portion of the focus ring substantially along the circumference close to the semiconductor substrate,
In other parts, the erosion is weak, and the attack of ions of the generated halide-based film is remarkable in a part along the circumference close to the semiconductor substrate. This is because an ion sheath with a large potential gradient is made in contact with the semiconductor substrate surface during etching,
Since a part of the ion sheath extends to the circumference of the focus ring close to the semiconductor substrate, it is considered that the ion impact at that part is large.

On the other hand, the pedestal portion 11 is located at a position sufficiently distant from the ion sheath, is in contact with the side wall portion of the cathode electrode 6 and is not located at a position facing the anode electrode 5, so that the plasma density and strength are reduced. Due to the fact that a dry etching chamber is usually designed, there is almost no ion bombardment. Accordingly, there is no need to replace the material, and a reasonable material that is inexpensive can be used.

On the other hand, if the same cost as the conventional one is allowed, it is possible to increase the replacement cycle as compared with the focus ring having an integral structure, and to replace the Al-F-based particles before the particle generation becomes too large. Therefore, it is possible to suppress a decrease in the production yield due to the remaining pattern.

When the focus ring has a two-body structure, the focus ring can have a composite material structure in which the material of the generating portion 10 and the material of the pedestal portion 11 are different. For example, by using a material having excellent resistance to erosion against gas plasma only for the generating unit 10 and configuring the pedestal unit 11 with an inexpensive material, it is possible to suppress the generation of particles. For example, a material containing Si such as a sintered ceramic such as SiN or SiC or quartz can be used for the generating portion 10, and an alumina ceramic can be used for the pedestal portion 11.

The generating unit 1 interacts with the etching gas plasma to form a highly volatile reaction product.
0 can be controlled in terms of material, and the selection of a material for preventing a reduction in semiconductor device manufacturing yield can be flexibly performed, which can be advantageous in terms of cost. Since SiN, SiC, quartz, etc. shown above generate fluorine in the etching gas and SiF having a high vapor pressure even at room temperature, Al-
No F-based particles are generated.

In addition, since it has been confirmed that the pedestal portion 11 is not eroded by the F plasma in the case of etching the silicon nitride film, an inexpensive material can be adopted, which is advantageous in cost. .

In the above-described embodiment, the case where CF ₄ gas containing halogen-based fluorine is used as the etching gas has been described. However, fluorine-based CF ₄ gas such as C ₅ F ₈ and C ₄ F ₆ may be used. (Perfluorocarbon), CHF ₃ , and SF ₆ , and the focus ring of this embodiment is effective for other halogen-based gases, such as chlorine-based gases such as BCl ₃ and Cl ₂ , and HBr. Further, as the dry etching apparatus, not only the parallel plate electrode system of FIG. 1 but also a system in which the electrode 6 is applied with a ground potential and a high frequency voltage is applied to the electrode 5, an ICP (inductive coupling type) system, an ECR (Electron Cyclotron Resonance).
Even in a dry etching apparatus of the system, the ion bombardment and the plasma state near the semiconductor substrate are almost the same, so that the focus ring of this embodiment can be applied.

[0027]

According to the focus ring of the plasma processing apparatus of the present invention, the first member having the surface facing the inside of the processing chamber substantially parallel to the surface of the substrate and having the first member close to the periphery of the substrate; Since it is composed of a second member disposed below the member to support the member, when the surface is deteriorated, instead of replacing the entire focus ring as in the related art,
Only the first member having a remarkable particle generation source can be replaced, and the operation cost of a plasma processing apparatus such as dry etching and the manufacturing cost of a semiconductor device can be suppressed.

According to the second aspect, since the first member of the focus ring is made of a material containing Si, the first member has excellent erosion resistance to gas plasma.

According to the third aspect, since the reactive gas contains halogen, a plasma containing halogen is generated and contributes to etching of the semiconductor substrate, and the first member is formed even if particles are generated by eroding the focus ring. It can be dealt with by replacing only.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a plasma processing apparatus using a focus ring according to an embodiment of the present invention.

FIG. 2A is a plan view of a focus ring according to an embodiment of the present invention, and FIG. 2B is a sectional view of the focus ring in a separated state.

FIG. 3 is a conceptual diagram of a conventional plasma processing apparatus using a focus ring.

FIG. 4A is a plan view of a conventional focus ring,
(B) is a sectional view of a separated state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing chamber 2 Exhaust port 3 Gas inlet 4 Shower head 5 Anode electrode 6 Cathode electrode 7 Substrate 8 Focus ring 9 High frequency power supply 10 Focus ring generating part 11 Focus ring pedestal part 12 Focus ring

Continued on front page F-term (reference) 4K057 DA01 DB06 DD01 DE04 DE08 DE11 DE20 DM03 DM04 DM29 DM35 DM40 DN01 5F004 AA01 AA16 BA14 BA20 BB28 BB29 DA00 DA01 DA04 DA11 DA16 DA18

Claims (3)

[Claims] 1. A substrate is installed on an electrode in a processing chamber into which a reactive gas is introduced, and is installed so as to surround a peripheral portion of the substrate when processing the substrate by generating plasma by the electrode. A focus ring of a plasma processing apparatus, comprising: a first member having a surface facing the inside of the processing chamber substantially parallel to a surface of the substrate, and a first member close to the periphery of the substrate; A focus ring for the plasma processing apparatus, comprising: a second member disposed below the support for supporting; 2. The focus ring according to claim 1, wherein the first member of the focus ring is made of a material containing Si. 3. The focus ring according to claim 1, wherein the reactive gas contains halogen.