JPH10218664A - Focus ring for plasma etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus ring for a plasma etching device comprising a vitrified carbon material little in consumption when etching and excellent in yield of products. SOLUTION: This focus ring for plasma etching device is composed of a vitrified carbon material satisfying the formula R>=(d002 -3.344)/0.135 in the relation between a relative intensity ratio R (IA/IB) of the spectrum intensity (IA) appearing in 1360±100cm<-1> band region and the spectrum intensity (IB) appearing in 1580±100cm<-1> band region in a Raman spectrum analysis by using argon laser beam of 5145 angstrom, and the average lattice spacing (d002 ) (angstrom) of graphite hexagonal net plane layer. Preferably, the relative intensity ratio R is regulated so as to be 1.0-2.0 and the average lattice spacing d002 is regulated so as to be 3.40-3.60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for forming a fine circuit pattern on a wafer surface by plasma etching in a process of manufacturing a semiconductor device typified by an LSI. Regarding focus ring.

[0002]

2. Description of the Related Art In a plasma etching apparatus, a reactive gas (C) is provided in an etching apparatus provided with a pair of parallel flat electrodes.
(F ₄ , Ar, O _2, etc.) while applying high frequency power between the upper and lower electrodes to discharge, and using the generated gas plasma, the non-photoresist part of the surface of the wafer placed on the lower electrode Is etched to form a fine circuit pattern with high accuracy. In this case, a focus ring functioning as an electric field compensation ring is arranged around the wafer in order to prevent the diffusion of plasma and efficiently cause the reactive gas converted into plasma to be incident on the surface of the wafer.

[0003] Japanese Patent Application Laid-Open No. 7-245292 discloses a focus ring for improving the uniformity of an etching rate. There has been proposed a plasma etching apparatus having a composite structure with a system member. This is tungsten silicide (WS
i) When etching a tungsten-based film such as tungsten (W) or the like, the reaction gas turned into plasma reacts with tungsten in the focus ring to generate a halogen compound, thereby suppressing the etching around the wafer. It is intended to improve the uniformity of the etching rate.

[0004] The focus ring is required to have excellent material properties such as corrosion resistance, plasma resistance, heat resistance, and conductivity which are not corroded by a reactive gas in a plasma state, and amorphous carbon has been conventionally used. Since the plasma properties are not sufficient, there is a drawback that the wear due to plasma irradiation progresses and the service life is short, and further, there is a drawback that particles are generated due to the wear. These problems have become more and more important as the degree of integration of LSIs has increased and the plasma density has increased and the required processing accuracy has increased.

A glassy carbon material is a macroscopically nonporous hard carbon material obtained by carbonizing a thermosetting resin, and has high strength, low chemical reactivity, gas impermeability, self-lubricating property, and robustness. It has excellent properties such as low impurities.
There is an advantage that fine particles that cause soiling of the wafer during the plasma etching process are not easily separated from the tissue.

[0006]

The present inventors have examined the relationship between the texture and the plasma resistance of the glassy carbon material constituting the focus ring, and found that the crystallinity and surface structure of the bulk were within a specified range. It was found that the glassy carbon controlled to be excellent in plasma was excellent in resistance to plasma, and its consumption was not accompanied by generation of particles, and it was confirmed that the carbonized carbon exhibited a suitable consumption form as a focus ring.

That is, the surface structure of the glassy carbon usually changes in accordance with the bulk crystallinity caused by the processing temperature conditions, the degree of orientation of the raw material resin, and the like. The treatment causes a specific structural change in the surface layer portion, and this change improves the plasma resistance in a plasma atmosphere and makes it possible to improve the durability as a focus ring.

The present invention has been developed on the basis of the above findings, and an object of the present invention is to provide a focus ring for a plasma etching apparatus capable of suppressing the generation of fine particles with less consumption by plasma. Is to provide.

[0009]

A focus ring for a plasma etching apparatus according to the present invention for solving the above-mentioned problems has a band of 1360 ± 100 cm ^-1 in Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 angstroms. Intensity ratio (IR / IB) of the spectral intensity (IA) appearing in the band and the spectral intensity (IB) appearing in the band of 1580 ± 100 cm ^-1 and the average lattice spacing of the hexagonal graphite layer d _{00 2} (unit: angstrom) is made of a vitreous carbon material satisfying the following expression (1). R ≧ (d ₀₀₂ −3.344) /0.135… (1)

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The focus ring for a plasma etching apparatus of the present invention is premised on being made of a glassy carbon material having a uniform structure obtained by calcining and carbonizing a thermosetting resin. 5ppm or less,
It is preferable that the flat plate is made of a high-purity material having a metal impurity content of 2 ppm or less and a total sulfur content of 30 ppm or less and having as high a surface smoothness as possible.

The degree of wear when a glassy carbon material is used for a focus ring for a plasma etching apparatus is as follows:
The purity, crystal structure, surface state, and the like of the glassy carbon used vary intricately due to complex effects. In general, Raman spectrum analysis of carbon material shows 1360 cm ^-1 and 158
Two peaks appear in the band of 0 cm ^-1 , and it is known that the relative intensity ratio of these peaks is related to the amount of defects of the crystal contained in the carbon structure and the irregularity of the lattice. For example, in the case of the artificial graphite is strong, the strength of 1580 cm ^-1 band than 1360 cm ^-1, in the reverse glassy carbon 1360
The peak of the cm ^-1 band becomes strong. However, the distribution of peaks and the relative intensity between bands differ depending on the properties of the glassy carbon, and the plasma resistance changes. In addition, the lattice constant C ₀ generally obtained by X-ray diffraction of a non-graphitizable carbon material such as glassy carbon is larger than that of a graphite material having a developed graphite network crystal. The average lattice spacing is also relatively wider than that of the graphite material, but this crystal structure also affects the plasma resistance and the generation of fine particles.

R ≧ (d ₀₀₂ −3.344) regulated by the present invention
The relational expression (1) of /0.135 is a Raman spectrum for the average lattice spacing d ₀₀₂ of the graphite hexagonal mesh layer whose surface properties of the glassy carbon material constituting the focus ring for the plasma etching apparatus are measured by X-ray diffraction. Characterized by having an amorphous carbon crystal structure in which the relative intensity ratio R of the two band peaks in the analysis is above a certain range of levels,
This property suppresses the consumption rate of the focus ring during the plasma etching operation, and at the same time, forms a material structure that does not cause detachment of fine particles. Therefore, R ≧
When the focus ring for a plasma etching apparatus is made of a glassy carbon material satisfying the requirement of (d ₀₀₂ −3.344) /0.135, the plasma resistance can be significantly improved.

In this case, the relative intensity ratio R in the Raman spectrum analysis is preferably in the range of 1.0 to 2.0. If the R value is less than 1.0, the crystal structure is not amorphous specific to glassy carbon, and the uniformity of the degree of wear is reduced. If the R value exceeds 2.0, carbonization is insufficient and the consumption rate is reduced. It is because it becomes big. A more preferable range of the R value is a range of 1.2 to 1.9.

Further, it is preferable that the value of the average lattice spacing d ₀₀₂ of the hexagonal reticular layer of graphite determined from the C (002) diffraction line by X-ray diffraction is in the range of 3.40 to 3.60 angstroms. If the value of the average lattice spacing d ₀₀₂ is less than 3.40 angstroms, the graphitization proceeds, the crystal structure does not show an amorphous structure specific to glassy carbon, and the generation of fine particles is increased.
If the thickness exceeds 0 Å, the degree of wear becomes non-uniform, and the speed of wear increases.

The focus ring for a plasma etching apparatus of the present invention comprising the glassy carbon material having the above properties can be manufactured as follows. First,
In order to increase the density and purity of the material, select a phenol-based, furan-based, or polyimide-based thermosetting resin with a residual carbon ratio of at least 40% or a mixture or compound of these as a raw material. use.
Since these raw material resins are usually in a powdery or liquid state, they are molded into a predetermined plate shape using an optimal molding means such as molding, injection molding, or casting according to the form. The molded body is subsequently subjected to a curing treatment at a temperature of 100 to 180 ° C. in the atmosphere. In the calcination treatment, the cured resin molded body is packed in a graphite crucible, or in a state sandwiched by graphite plates, and packed in an electric furnace maintained in an inert atmosphere such as nitrogen or argon, or a lead hammer furnace.
This is done by heating to 0 ° C. Furthermore, the carbonized fired body is placed in a vacuum furnace capable of replacing the atmosphere, and while flowing a halogen-based purified gas, at 1500 ° C. or higher, preferably 1 ° C.
A heat treatment is performed at a temperature of 800 ° C. or more to perform a high-purity treatment.
Next, the surface property of the glassy carbon material is changed to a predetermined property by mechanically polishing the surface of the fired body to increase the surface smoothness. This surface treatment may be performed between the calcination treatment step and the high-purification treatment step.

The mechanical polishing process includes a lapping process using various abrasives, a polishing process such as a buffing process, and the like. Examples of the abrasive particles include metal oxides such as Al ₂ O ₃ abrasives, and SiC abrasives. In addition to carbides such as grains, borides such as TiB ₂ abrasives, nitrides such as BN ₄ abrasives,
A single abrasive such as diamond is used. In addition, it is preferable that the abrasive grains are sequentially shifted from a larger one to a smaller one to increase the surface smoothness. When such surface polishing is performed, mechanical energy such as compression, shearing, and friction is applied to the surfaces of the abrasive grains and the glassy carbon material, and the temperature rise and compression occurring between the abrasive grains and the glassy carbon material are reduced. Phenomena such as generation of force, accumulation of strain energy, and generation of structural defects act in combination to induce a mechanochemical change on the surface, and as a result, it is possible to improve and improve the consumption mode.

As described above, in the focus ring for a plasma etching apparatus of the present invention, by controlling the structure of the surface layer of the glassy carbon material within a specific range, the plasma ring resistance is improved when the focus ring is formed. The wear characteristics are significantly improved, and the generation of particles can be effectively suppressed. In addition, these textures can be obtained by appropriately controlling the selection of the purified raw resin, the temperature conditions such as the heating rate during the calcination and the refining treatment, and the conditions during the surface polishing. Properties can be ensured.

[0018]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples, but the embodiments of the present invention are not limited to these examples.

Example 1 (1) Production of Focus Ring Phenol and formalin purified by distillation under reduced pressure were condensed according to a conventional method to prepare a phenol resin precondensate. The raw resin solution was poured into a 400 mm square polypropylene vat, degassed under a reduced pressure of 10 Torr or less for 3 hours, and then placed in an electric oven at 80 ° C. and left for 24 hours to form a plate. The molded plate was taken out of the vat, and the temperature was raised to 180 ° C. at a rate of 10 ° C. per hour, followed by a curing treatment for 24 hours. The molded resin sheet was set in an electric furnace while sandwiched between high-purity graphite sheets, and the surroundings were covered with graphite powder having a total ash content of less than 100 ppm.
The temperature was raised to 1000 ° C. at a rate of temperature increase of 1000 ° C./hr, and calcined and carbonized.

The obtained flat glassy carbon plate having a thickness of 2.5 mm was wrapped in the order of 35 minutes at an abrasive particle size of # 800 and 25 minutes at an abrasive particle size of # 2000 using SiC abrasive grains as an abrasive. The surface was smoothed.
Next, a vacuum furnace capable of replacing the atmosphere [manufactured by Tokai High Heat Co., Ltd.
TP300] and Cl ₂ / He (molar ratio: 5/9) in the furnace.
The purified gas of 5) was heated at a temperature of 2000 ° C. while flowing at a supply rate of 5 liters / minute to perform a high-purity treatment. This highly purified product is processed into a ring shape with an outer diameter of 300 mm and an inner diameter of 200 mm using a diamond cutting tool, and is further buffed with a SiC abrasive particle size of # 4000 for 25 minutes and a SiC abrasive particle size of # 8000 for 35 minutes. Polishing and final polishing were performed to obtain a focus ring.

(2) Measurement of Material Properties Regarding the focus ring for the plasma etching apparatus made of the glassy carbon material manufactured as described above,
An average lattice spacing d ₀₀₂ was measured from a C (002) diffraction line by performing a line diffraction measurement. Further, the surface of the focus ring was irradiated with argon ion laser light having a wavelength of 5145 angstroms to perform Raman spectrum analysis, and 1360 ±
The relative intensity ratio R in both bands of 100 cm ^-1 and 1580 ± 100 cm ^-1 was calculated. The results satisfied the characteristic requirements of the present invention.

(3) Evaluation of Performance Next, this focus ring was set on the outer periphery of the wafer loading portion of the plasma etching apparatus, and the reaction gas: CF ₄ ,
Carrier gas; argon, gas pressure in reaction chamber: 0.5 Torr, power supply frequency: 13.5 MHz, 8
An inch silicon wafer oxide film was plasma etched. Table 1 shows the amount of reduction in the thickness of the focus ring after 200 hours of processing (the amount of consumption) and the product yield when a 64-Mbit DRAM was manufactured from the processed wafer, in comparison with the properties of the glassy carbon material.

Example 2 In the manufacturing process of Example 1, the temperature of the high-purification treatment was set to 2
The temperature was changed to 100 ° C., and the other conditions were all the same as in Example 1 to produce a focus ring of a glassy carbon material. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 3 In the manufacturing process of Example 1, the temperature during the high-purification treatment was changed to 2100 ° C., and the surface finish polishing after the high-purification treatment was performed only for 45 minutes with a SiC abrasive particle size of # 6000 for 45 minutes. Manufactured a focus ring made of a glassy carbon material under the same conditions as in Example 1. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 4 In the manufacturing process of Example 1, the temperature during the high-purification treatment was changed to 2500 ° C., and the surface finish polishing after the high-purification treatment was performed only for 45 minutes with a SiC abrasive particle size of # 3000. Manufactured a focus ring made of a glassy carbon material under the same conditions as in Example 1. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 5 In the manufacturing process of Example 1, the temperature of the purification treatment was set to 1
The temperature was changed to 500 ° C., and all other conditions were the same as in Example 1 to produce a focus ring of a glassy carbon material. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 6 In the manufacturing process of Example 1, the temperature during the high-purification treatment was changed to 3000 ° C., and the surface finish polishing after the high-purification treatment was performed only for 10 minutes with the SiC abrasive particle size # 3000. Manufactured a focus ring made of a glassy carbon material under the same conditions as in Example 1. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

COMPARATIVE EXAMPLE 1 In the production process of Example 1, polishing was performed for 25 minutes at a grain size of # 3000 and for 35 minutes at a grain size of # 8000 for surface treatment after firing and carbonizing at 1000.degree. Finish polishing after the chemical treatment was stopped, and a focus ring made of a glassy carbon material was manufactured under the same conditions as in Example 1 except for all other conditions. The obtained glassy carbon material deviated from the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 In the manufacturing process of Example 1, the temperature during the high-purity treatment was set to 1
The temperature was changed to 200 ° C., and all other conditions were the same as in Example 1, to produce a focus ring for a plasma etching apparatus made of a glassy carbon material. The obtained glassy carbon material deviated from the characteristic requirements of the present invention.
The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 In the production process of Example 1, the temperature during the high-purity treatment was set to 2
A focus ring made of a glassy carbon material was manufactured under the same conditions as in Example 1 except that the temperature was changed to 500 ° C., and the finish polishing after the high-purification treatment was not performed. The obtained glassy carbon material deviated from the characteristic requirements of the present invention. The performance of this focus ring was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0031]

[Table 1] (Table note) * 1 Relative intensity ratio R * 2 Average lattice spacing of hexagonal graphite layer in angstrom

From the results shown in Table 1, it can be seen that all of the focus rings made of the glassy carbon material of the examples satisfying the characteristic requirements of the present invention consume less amount and have higher product yield than the comparative examples. However, in Example 5, the relative strength ratio R of the glassy carbon material was out of the range of 1.0 to 2.0.
6, or the average lattice spacing d ₀₀₂ is 3.40 to 3.60.
In Examples 5 and 6 out of the angstrom range, it is recognized that the consumption amount is slightly large and the product yield is slightly lower.

[0033]

As described above, according to the present invention, the relative intensity ratio of two specific bands appearing by Raman spectrum analysis and the average lattice spacing d _{002 of the} hexagonal reticular layer of graphite obtained by X-ray diffraction are obtained. By selecting a glassy carbon material having properties within a specific range, it is possible to provide a focus ring with a small amount of consumption and a high product yield with less generation of fine particles. Therefore, stable etching can be performed at all times, and the life of the focus ring can be significantly extended.

Claims (3)

[Claims] 1. A Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 angstroms shows a spectral intensity (IA) appearing in a band of 1360 ± 100 cm ^{−1 and} a band appearing in a band of 1580 ± 100 cm ^−1. the relative intensity ratio of the spectral intensity (IB) R (IA / IB), the average lattice spacing d _{00 2} graphite hexagonal plane layer (unit: angstrom), but, glassy carbon satisfying the following relationship (1) A focus ring for a plasma etching apparatus, comprising a material. R ≧ (d ₀₀₂ −3.344) /0.135… (1) 2. A focus ring for a plasma etching apparatus according to claim 1, wherein said relative ring has a relative intensity ratio R of 1.0 to 2.0. 3. The average lattice spacing d _{002 of the} hexagonal reticular layer of graphite.
3. A focus ring for a plasma etching apparatus according to claim 1, wherein said focus ring is made of a glassy carbon material in a range of 3.40 to 3.60 angstroms.