JP2003023002A - Chamber inner wall protection member and plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member for protecting an inner wall of a chamber of a plasma processing apparatus which can be used stably for a long time, and a plasma processing apparatus in which the protective member is arranged. SOLUTION: This protection member has a hollow shape and protects an inner wall of a chamber of the plasma processing apparatus. The protection member is formed as an integral structure from a glassy carbon material, and has a protrusion at a bottom portion extending inward. As a glass carbon material,
Volume resistivity of 1 × 10 ^-2 Ω · cm or less, thermal conductivity of 5 W /
Preferably, the protective member has a characteristic of m · K or more, the thickness of the protective member is 4 mm or more, and the average surface roughness (Ra) of its inner surface is 2.0 μm.
m or less. The plasma processing apparatus is configured such that the chamber inner wall protection member is disposed along the chamber inner wall of the plasma processing apparatus, the chamber inner wall and the protection member are electrically connected, and the chamber is grounded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in the process of manufacturing semiconductor devices such as ICs and LSIs.
For example, the present invention relates to a chamber inner wall protection member for protecting an inner wall of a chamber of a plasma processing apparatus such as a plasma etching apparatus for a silicon wafer or a plasma CVD apparatus, and a plasma processing apparatus in which the protection member is arranged.

[0002]

2. Description of the Related Art A plasma etching process is used.
The plasma processing chamber has a lower electrode inside the plasma processing chamber.
The pole and the upper electrode are placed at the positions facing each other at a predetermined interval.
And CF _Four, CHF₃, Ar, O₂Reactive gas such as
Let it flow out of the pores of the upper electrode and
Plasma is generated by the applied high frequency power. This program
Silicon wafer etc. placed on the lower electrode by plasma
The etching process is performed.

Aluminum, graphite, glassy carbon, silicon, etc. are used for the electrodes, and aluminum and alumina whose surface is oxidized are used for the inner wall member of the plasma processing chamber.

However, as the plasma etching process is continued, the inner wall of the plasma processing chamber is chemically eroded to generate dust and wear, which adheres to the wafer surface and becomes a defective product, resulting in a decrease in yield. There is also a problem that the life of the chamber itself is shortened. Therefore, measures have been taken to suppress the abrasion of the inner wall portion due to the plasma by providing a protective member on the inner wall portion of the plasma processing chamber.

For example, in Japanese Unexamined Patent Publication No. 9-275092, a chamber in which a substrate to be processed is stored, a pump for exhausting the inside of the chamber, and a processing gas introduced into the chamber are converted into plasma. A plasma processing apparatus comprising: an electrode means for irradiating the substrate to perform a desired process, wherein a protective wall member is replaceably attached along a inner wall of the chamber through a predetermined space, and the space. And a cooling means for suppressing an increase in the surface temperature of the protective wall member due to the heat generated in the chamber by introducing a cooling gas into the plasma processing apparatus.

Japanese Patent Application Laid-Open No. 9-275092 relates to a cooling structure for a protective wall member provided inside a chamber of a plasma processing apparatus, and adsorbs a polymer represented by C _x F _y generated by plasma formation on the protective wall member. This prevents the polymer from adhering to any place in the chamber. Since the protective wall member itself can be easily replaced, the efficiency of the cleaning work is improved, and the temperature rise due to plasma on the surface of the protective wall member is prevented, so that the process can be stabilized.

Further, in JP-A-9-289198, in a plasma processing apparatus having a plasma processing chamber in which electrodes for plasma generation are arranged, at least the surface of a portion of the plasma processing chamber other than the electrodes exposed to plasma Is formed of glassy carbon, and a plasma processing chamber in which two electrodes for plasma generation are arranged and a plasma region is formed between these electrodes. A protective member for a plasma processing apparatus, which is disposed on both sides so as to cover the plasma area, wherein at least the surface of the protective member on the plasma area side is formed of glassy carbon. A member is disclosed.

That is, according to Japanese Unexamined Patent Publication No. 9-289198, since the portion exposed to plasma is formed of glassy carbon, erosion and damage due to plasma are reduced, and long-life particles (dust) are generated. It is rarely generated, and contamination of the object to be treated with dust is prevented.

[0009]

However, since the plasma resistance of the glassy carbon material differs depending on the material properties of the glassy carbon, it is necessary to select an appropriate material in order to exert the suitable performance as the chamber inner wall protection member. It was also found that it is necessary to consider the structure of the protective member in order to perform stable etching treatment for a long time with the plasma processing apparatus in which the chamber inner wall protective member is arranged.

The inventors of the present invention have conducted extensive studies on the material properties of the glassy carbon material suitable as a chamber inner wall member for protecting the chamber inner wall portion of the plasma processing apparatus and the structure of the protective member, and as a result, have excellent plasma resistance. Achieved the present invention by finding out the material properties of the glassy carbon material capable of forming and maintaining a stable plasma state with less generation of dust, and finding the most effective structure for performing stable etching treatment for a long time. It was done.

That is, an object of the present invention is to provide a chamber inner wall protection member of a plasma processing apparatus which can be stably used for a long time by specifying the material property of a glassy carbon material, and a plasma processing apparatus in which the protection member is arranged. To provide.

[0012]

The chamber inner wall protection member according to the present invention for achieving the above object is a hollow protection member, and the protection member is formed of a glassy carbon material in an integral structure. The structural feature is that the bottom has a protrusion extending inward. Preferably, the volume resistivity is 1 × 10 ^-2 Ω · cm or less, and the thermal conductivity is 5 W / m ·
It is formed as an integral structure from a glassy carbon material having characteristics of K or more. The thickness of the protective member is preferably 4 mm or more, and the average surface roughness (Ra) of the hollow inner surface is 2.0 μm.
m or less is preferable. Here, the hollow shape includes not only a cylindrical shape but also a shape in which necessary holes and cutouts are formed. In addition to a cylindrical shape, a hollow prism is also included.

The plasma processing apparatus of the present invention preferably has a volume resistivity of 1 × 10 ⁻² Ω · cm or less and a thermal conductivity of 5 W / along the inner wall of the chamber of the plasma processing apparatus.
Has characteristics of m · K or more, and preferably has a thickness of 4 mm
The chamber inner wall protection member formed in a hollow shape of an integral structure from the glassy carbon material having the above-mentioned average surface roughness (Ra) of 2.0 μm or less is arranged,
A structural feature is that the chamber inner wall and the protection member are electrically connected and the chamber is grounded.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A glassy carbon material is a unique hard carbon material that macroscopically exhibits a non-porous three-dimensional network structure and has a glassy dense tissue structure. It is a special carbon substance that has excellent chemical stability, gas impermeability, wear resistance, surface smoothness, and robustness, and has few impurities.

According to the present invention, a glassy carbon material having these characteristics is processed into a hollow structure having an integral structure to form a chamber inner wall protection member, and a protrusion extending inward is formed at the bottom of the hollow protection member. It is characterized by having a part.
The glassy carbon material that constitutes the protective member has a volume resistivity of 1 × 10 ⁻² Ω · cm or less and a thermal conductivity of 5 W / m ·
A glassy carbon material having characteristics of K or more is preferable.
The protection member is manufactured by forming a wafer-shaped carbon material having a hollow shape on the side surface thereof with a wafer carry-out hole, a carry-in hole and a monitoring hole, an exhaust pipe notch, and the like to form an integral structure. The thickness of the protective member is preferably 4 mm or more, and the average surface roughness (Ra) of the hollow inner surface is preferably 2.0 μm or less.

If the volume resistivity exceeds 1 × 10 ⁻² Ω · cm, it is difficult for the potential on the inner surface of the chamber inner wall protection member to approach the ground potential, making it difficult to form good plasma. When the thermal conductivity is less than 5 W / m · K, the temperature difference between the chamber inner wall protection member and the processing container that controls the temperature of the inner surface is large, and thus it takes a long time to control the temperature. Further, since the temperature distribution becomes non-uniform, stable plasma formation becomes difficult. Further, if the structure is not the integral type but the split type, the potential on the inner surface of the protective member becomes non-uniform, and it becomes difficult to form good plasma.

Further, the chamber inner wall protecting member preferably has a thickness of 4 mm or more. When the thickness of the protective member becomes thin, the cross-sectional area of the annular cross section becomes small, and the electrical resistance in the vertical direction increases when the protective member is placed in the chamber. It becomes relatively large and it becomes difficult to form a good plasma. More preferably, the thickness is 8 mm or more,
The durability is improved.

The inner surface of the hollow protective member preferably has an average surface roughness (Ra) of 2.0 μm or less.
The inner surface of the chamber inner wall protection member reacts with corrosive gas during plasma processing and is consumed little by little, but the average surface roughness (Ra)
This is because if the particle size exceeds 2.0 μm, particles may fall off from the inner surface of the chamber inner wall protection member depending on the form of consumption. The surface of the wafer carry-out / carry-in hole, the monitoring hole, and the notch of the exhaust pipe are also consumed during the plasma processing, so that the average surface roughness (Ra) is 2.0.
It is preferably not more than μm.

In the plasma processing apparatus of the present invention, preferably, a chamber inner wall protection member formed of a glassy carbon material having the above-mentioned material properties into a hollow structure having an integral structure is provided along the chamber inner wall portion of the plasma processing apparatus. The inner wall of the chamber and the protection member are electrically connected to each other and the chamber is grounded. This is because when the chamber inner wall portion and the inner wall protection member are not electrically connected to each other and are not grounded, the plasma becomes unstable and stable and uniform plasma processing becomes difficult. In order to electrically connect the chamber inner wall protection member to the chamber inner wall portion, the aluminum oxide layer formed on the surface of the inner wall member is removed and the bottom surface of the protection member is brought into direct contact with the aluminum material. it can.

The glassy carbon material forming the chamber inner wall protection member of the present invention can be manufactured as follows. First, in order to increase the density and purity of materials, the rate of residual coal that has been previously refined as a raw material should be at least 4
0% or more of phenol type, furan type, polyimide type or a thermosetting resin in which these are blended is selectively used. Since these raw material resins are usually in the form of powder or liquid, they are molded into a hollow shape by an appropriate molding method such as molding, injection molding or cast molding according to their form. The molded body is subsequently subjected to a curing treatment in the atmosphere at a temperature of 100 to 250 ° C., and then it is packed in a graphite crucible or sandwiched between graphite plates and kept in a non-oxidizing atmosphere such as nitrogen or argon. It is packed in a furnace or a lead hammer furnace and heated to a temperature of 800 ° C. or higher to be carbonized by firing and converted into a glassy carbon material.

The calcined and carbonized glassy carbon material is put into a vacuum furnace capable of atmosphere substitution, and is heated to a temperature of 1500 ° C. or higher while flowing a purification gas of halogen type such as chlorine gas to be highly purified. It The highly purified glassy carbon material is machined using a hard tool such as diamond, and the inner surface is polished to obtain the chamber inner wall protection member of the present invention.

Hereinafter, examples of the present invention will be specifically described in comparison with comparative examples.

Examples 1 to 3 and Comparative Examples 1 to 3 Liquid phenol-formaldehyde resin [PR940 manufactured by Sumitomo Durez Co., Ltd.] was poured into a polypropylene mold and degassed for 3 hours under a reduced pressure of 10 Torr or less. After 8
It was placed in an electric oven at 0 ° C. and left for 3 days to obtain a cylindrical shaped body. After removing the molded body from the mold, 100
3 days at ℃, 3 days at 130 ℃, 3 days at 160 ℃, 2
It was cured by heating at 00 ° C. for 3 days. The cured product was calcined and carbonized in an electric furnace maintained in a nitrogen atmosphere at a heating rate of 3 ° C / hr and a heating temperature of 1000 ° C. Then, a heating furnace was used to change the heating temperature in a vacuum furnace capable of replacing the atmosphere to perform a purification treatment.

The glassy carbonaceous materials thus obtained having different characteristics were machined using a diamond tool, and then the inner surface was polished to obtain a hollow chamber inner wall protection member having different surface roughness and thickness. It was made.

These chamber inner wall protection members were arranged on the inner wall of the plasma processing chamber 1 shown in FIG. The processing chamber 1 is made of aluminum whose surface is oxidized, and is grounded. The chamber inner wall protection member 2 is electrically connected to the processing chamber at the bottom surface 101 as shown in FIG. Note that the aluminum oxide layer is peeled off from the surface of the processing chamber that is in contact with the bottom surface 101. The bottom surface protrusion 104 of the chamber inner wall protection member 2 has an aluminum member 10 whose surface is oxidized.
It is fixed at 2. As a result, the chamber inner wall protection member 2 is sufficiently electrically conducted at the bottom surface. In addition, a screw cover 103 is provided on the screw of the oxidized aluminum member 102 to prevent corrosion by plasma.

The semiconductor wafer 3 is held on the lower electrode 5 in the processing chamber 1 via the electrostatic chuck 4. The lower electrode 5 has a high frequency power supply (eg 800 kHz) 1
1 is connected. The lower electrode 5 is arranged on the bottom surface of the processing chamber 1 via an insulator 6. The upper electrode 7 is the conductor portion 8
And a high frequency power source (for example, 27.12 MHz) 12 is connected to the conductor portion 8. The conductor portion 8 and the processing chamber 1 are arranged via an insulator 9.

From above the upper electrode 7, as a processing gas, C _{4 is used.}
F ₈ and O ₂ and Ar were introduced into the chamber 1, two high frequency powers of the upper electrode and the lower electrode were applied to generate plasma, and the SiO ₂ film of the wafer 3 was etched.
The number of dusts and the in-plane uniformity when 100 wafers were etched were measured. The results are shown in Table 1. In addition,
The in-plane uniformity is an index showing the uniformity of etching at the center and the edge of the wafer. When the etching rate at the center of the wafer is A and the etching rate at the edge of the wafer is B, the following equation (Equation 1) is used. It is a calculated value. This represents what percentage of the average etching rate is the difference between the etching rate at the center and the edge of the wafer and their average etching rates. Therefore, it is indicated that the larger the value obtained by taking ± from this value is, the more nonuniform the value is, and the smaller the value is, the more uniform the value is. In this measurement, a wafer having a diameter of 200 mm was used.

[0028]

[Equation 1]

[0029]

[Table 1]

From Table 1, the chamber inner wall protection member of the example formed of the glassy carbon material having the material properties of the present invention produced less dust than the comparative example, and
There was also in-plane etching uniformity. If the chamber inner wall protection member is formed in a rectangular tube shape, it can be applied to an LCD etching apparatus. Further, in this embodiment, high frequency power was applied to both the upper and lower electrodes, but a device for applying high frequency power only to the upper electrode to ground the lower electrode and the chamber,
Alternatively, it can be applied to a device in which high frequency power is applied only to the lower electrode to ground the upper electrode and the chamber.

[0031]

As described above, according to the present invention, the chamber inner wall protection member formed of the glassy carbon material and having the specified structure, and the plasma processing apparatus in which the chamber inner wall protection member is arranged,
It has excellent plasma resistance and enables stable plasma treatment for a long time.

[Brief description of drawings]

FIG. 1 is a diagram showing a plasma processing apparatus.

FIG. 2 is a diagram in which the chamber inner wall protection member is electrically connected to the processing chamber at the bottom surface.

[Explanation of symbols]

1 Plasma processing chamber 2 Chamber inner wall protection member 3 Semiconductor wafer 4 electrostatic chuck 5 Lower electrode 7 Upper electrode 13 Exhaust pipe 101 Bottom surface of chamber inner wall protection member 102 Aluminum material 103 screw cover 104 Projection

Continued front page    (72) Inventor Koichi Kazama             TBS release, 5-3-6 Akasaka, Minato-ku, Tokyo             Sending Center Tokyo Electron Limited F-term (reference) 4K030 FA03 KA08 KA46                 5F004 AA06 AA14 AA15 BA04 BA09                       BB22 BB29 BD03 BD04

Claims (6)

[Claims] 1. A hollow protective member for protecting an inner wall of a chamber of a plasma processing apparatus, wherein the protective member is formed of a glassy carbon material in an integral structure, and has a protrusion extending inward at a bottom portion. A chamber inner wall protection member characterized by: 2. The protective member has a volume resistivity of 1 × 10 ⁻² Ω.
The chamber inner wall protection member according to claim 1, which is made of a glassy carbon material having characteristics of not more than cm and thermal conductivity of not less than 5 W / mK. 3. The chamber inner wall protection member according to claim 1, wherein the thickness of the protection member is 4 mm or more. 4. The chamber inner wall protection member according to claim 1, wherein the average surface roughness (Ra) of the inner surface is 2.0 μm or less. 5. The chamber inner wall protection member according to claim 1 is arranged along the chamber inner wall portion of the plasma processing apparatus to electrically connect the chamber inner wall portion and the protection member. A plasma processing apparatus, wherein the chamber is grounded. 6. The plasma processing apparatus according to claim 5, wherein the inner wall of the chamber and the protective member are electrically connected to each other at the bottom surface of the protective member.