JP3708203B2 - Electrode plate for plasma etching - Google Patents

Description

【００３４】
表１の結果から、本発明の特性要件を満たす実施例によるガラス状炭素材からなる電極板は比較例品に比べていずれも電極消耗量が少なく、製品歩留りも高いことが判る。しかし、ガラス状炭素材の相対強度比Ｒが１．０〜２．０の範囲を外れる実施例６や、平均格子面間隔ｄ₀₀₂ が３．４０〜３．６０オングストロームの範囲を外れる実施例５では微細パーティクルの脱落により製品歩留りが若干低下する様子が認められた。
【００３５】
【発明の効果】
以上のとおり、本発明によればラマンスペクトル分析により出現する２つの特定バンド域の相対強度比とＸ線回析により求めた黒鉛六角網面層の平均格子面間隔ｄ₀₀₂ が特定範囲にある性状のガラス状炭素材を選択することにより、エッチング消耗が少なく、微細パーティクルの発生がない製品歩留りに優れるプラズマエッチング用電極板を提供することが可能となる。したがって、常に安定したエッチング加工が保証されるうえ、電極板の寿命を大幅に延長することができる。[0001]
[Technical field to which the invention belongs]
The present invention relates to a plasma etching electrode plate made of a glassy carbon material used when plasma etching a silicon oxide film on a wafer surface in a semiconductor device manufacturing process.
[0002]
The plasma etching process is performed by applying a high frequency power between the electrodes while introducing a reactive gas (CF ₄ , Ar, O _2, etc.) into an etching apparatus provided with a pair of parallel plane electrodes, and generating a gas plasma. This is a step of forming a fine circuit pattern with high accuracy by etching a portion which is not photoresisted by using. In addition to excellent conductivity, the planar electrode used in this plasma etching process requires high purity that does not contaminate the wafer and chemical stability that is not easily etched, and currently satisfies these material requirements. As an example, an electrode plate formed of a glassy carbon material is useful.
[0003]
A glassy carbon material is a macroscopically non-porous hard carbon material obtained by carbonizing a thermosetting resin, and is excellent in high strength, low chemical reactivity, gas impermeability, self-lubricity, fastness, etc. Although it has characteristics such as few impurities, there is an advantage that fine particles that cause contamination of the wafer during the plasma etching process are difficult to separate from the structure. However, as the degree of semiconductor integration increases more and more recently, strict material requirements are imposed on electrode materials for plasma etching, and the level of particles adhering to the wafer surface and the degree of wear are severely reduced. It is requested. For this reason, many proposals have been made for material improvements aimed at glassy carbon electrodes for plasma etching.
[0004]
[Prior art]
For example, the properties such as purity, porosity, pore diameter, crystal structure, etc. are to be improved. The porosity is 0.0002 to 0.0020%, and the crystallite is not detected by X-ray diffraction and contains impurities. Carbon member for plasma device made of glassy carbon material with an amount of 5 ppm or less (Japanese Patent Laid-Open No. 3-33007), with a maximum pore size of 1 μm or less, an average pore size of 0.7 μm or less, and a porosity of 1% or less. An electrode plate for plasma etching made of high-purity glassy carbon (Japanese Patent Laid-Open No. 3-119723), a plate-like body made of high-purity glassy carbon and having a thickness of 2 mm or more, with grain boundaries on the surface and internal structure An electrode plate for plasma etching that does not substantially exist and has a maximum pore diameter of 1 μm or less (Japanese Patent Laid-Open No. 3-285086), has a purity characteristic of 5 ppm or less, a metal impurity of 2 ppm or less, and a total sulfur content of 30 ppm or less. Sex lattice spacing (002) 0.375Nm or less, the size of crystallite (002) is more than 1.3 nm, and the material properties are a specific gravity less than 1.50, bending strength 1100 kg / cm ² or more glassy carbon Electrode plate for plasma etching made of (Japanese Patent Laid-Open No. 5-320955), Electrode plate for plasma etching made of glassy carbon having a crystal having a lattice constant C ₀ of 6.990 angstroms or less (JP-A-6-128761) Etc. have been proposed.
[0005]
In addition, as an object for surface properties, a plasma etching electrode plate (Japanese Patent Laid-Open No. Hei 6-128762) made of glassy carbon having a surface smoothness Rmax of 6 μm or less at a portion consumed by plasma is also disclosed. As a technique for specifying the raw material system of glassy carbon, an electrode plate for plasma etching (JP-A-5-347276) made of a glassy carbon material produced from phenol resin and polycarbodiimide resin as a raw material, or polycarbodiimide resin as a raw material An electrode plate for plasma etching (Japanese Patent Laid-Open No. 5-347278) made of a manufactured glassy carbon material has been proposed.
[0006]
As a result of studying the relationship between the structural properties of glassy carbon constituting the electrode plate for plasma etching and the degree of electrode wear during the etching process, the present applicant has determined that the surface properties of the glassy carbon constituting the electrode plate are constant. Elucidation of the fact that the degree of electrode wear is effectively reduced when the relative spectral intensities of the two Raman bands identified in the Raman spectrum analysis by the argon ion laser in the wavelength range are within a certain range. [R = IA / IB] formula (where IA is the spectral intensity in the 1360 ± 10 cm ⁻¹ band region and IB is the spectral intensity in the 1580 ± 10 ⁻¹ band region) R value defined by) is in the range of 1.0 to 2.0, and the half width of the IA is 30～90Cm ^-1 FWHM of IB proposed a plasma etching electrode plate of glassy carbon having the properties in the respective ranges of 40~100cm ^-1 (Japanese Patent Application No. 6-279984).
[0007]
[Problems to be solved by the invention]
The relative intensity ratio R in the Raman spectrum analysis slightly changes depending on the crystal structure of the carbon, but the glassy carbon in the property range specified in the invention of Japanese Patent Application No. 6-279984 has purity, crystallinity, and porosity properties. In addition, when the electrode plate for plasma etching is used in all surface states, it effectively improves the etching resistance and functions to suppress the consumption rate. The present inventor has continued research to further improve this prior art, and in addition to the relative intensity ratio by the Raman spectrum analysis described above, the graphite hexagonal network layer, which is an indicator of the bulk crystallinity of glassy carbon, is used. It was found that the lattice spacing is closely related to the etching consumption, and the electrode consumption is further improved when the characteristics of both satisfy a certain relationship.
[0008]
The present invention was developed on the basis of such knowledge, and the objective solution is a glassy carbon in which the degree of electrode wear is small and a stable etching process operation is always guaranteed without generation of fine particles. An object of the present invention is to provide a plasma etching electrode plate.
[0009]
[Means for Solving the Problems]
The electrode plate for plasma etching according to the present invention for solving the above-described problems is a spectral intensity (IA) that appears in a band region of 1360 ± 100 cm ⁻¹ in Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 angstroms. And the relative intensity ratio R (IA / IB) of the spectral intensity (IB) appearing in the band range of 1580 ± 100 cm ⁻¹ and the average lattice spacing d ₀₀₂ (unit: angstrom) of the graphite hexagonal mesh layer, It is characterized by being composed of a glassy carbon material that satisfies the relationship of the following formula (1).
R ≧ (d ₀₀₂ −3.344) /0.135 (1)
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The electrode plate for plasma etching according to the present invention is premised on glassy carbon having a uniform structure obtained by firing and carbonizing a thermosetting resin, but the purity characteristics are 5 ppm or less in total ash, 2 ppm or less in metal impurities, A flat plate having a high-purity material having a total sulfur content of 30 ppm or less and a surface smoothness as high as possible is preferable.
[0011]
In the glass-like carbon material, when the Raman spectroscopy using an argon ion laser beam having a wavelength of 5145 Angstroms, the spectral intensity in the spectrum strength (IA) 1580 ± 100cm ^-1 band region in 1360 ± 100 cm ^-1 band region (IB R value, which is the relative intensity ratio (IA / IB), and the average lattice spacing d ₀₀₂ (unit: angstrom) of the graphite hexagonal network layer satisfies the relationship R ≧ (d ₀₀₂ −3.344) /0.135 This is a physical requirement of the present invention.
[0012]
Among these, the relative intensity ratio R in the Raman spectrum analysis is preferably in the range of 1.0 to 2.0. When the R value is less than 1.0, the crystal structure is not amorphous characteristic of glassy carbon and the etching wear resistance is reduced. On the other hand, when the R value exceeds 2.0, carbonization is insufficient and the electrode plate is used as an electrode plate. Qualification is inferior, and the degree of etching consumption increases. A more preferable range of the R value is in the range of 1.2 to 1.9.
[0013]
The average lattice spacing d ₀₀₂ of the graphite hexagonal mesh layer is determined from the C ₀ (002) diffraction peak by X-ray diffraction, and this d ₀₀₂ spacing may be in the range of 3.40 to 3.60 Å. preferable. A crystal structure having an average lattice spacing d ₀₀₂ less than 3.40 angstroms does not exhibit an amorphous structure peculiar to glassy carbon due to the progress of graphitization. If it exceeds 1, the carbon structure becomes insufficient, the etching wear resistance as the electrode plate is lowered, and the degree of wear of the electrode plate is also increased.
[0014]
The degree of wear when a glassy carbon plate is used as an electrode plate for plasma etching varies slightly due to the influence of the purity, crystal structure, surface state, etc. of the glassy carbon used. Generally, the carbon material two peaks out current in the band region of 1360 cm ^-1 and 1580 cm ^-1 when a Raman spectrum analysis, their relative intensity ratio to irregularities of defects and lattice of crystals contained in the structure of the carbon It is known to be involved. For example, in the case of artificial graphite, but the intensity of the 1580 cm ^-1 band is higher than 1360 cm ^-1, a peak of 1360 cm ^-1 band in the reverse increases the glassy carbon. However, the distribution of peaks and the relative strength between bands vary depending on the properties of glassy carbon, and the etching resistance changes. On the other hand, the lattice constant C ₀ obtained by X-ray diffraction of a non-graphitizable carbon material such as glassy carbon is larger than that of a carbon material having a graphite structure in which a graphite network crystal is developed, and at the same time the average lattice plane Although the interval is relatively wider than that of the graphite material, this crystal structure also affects the etching resistance and the generation of fine particles.
[0015]
The relational expression (1) of R ≧ (d ₀₀₂ −3.344) /0.135 regulated in the present invention is a graphite hexagonal network surface in which the surface property of the glassy carbon material constituting the electrode plate for plasma etching is measured by X-ray diffraction. It is characterized by having an amorphous carbon crystal structure in which the relative intensity ratio R of the two band peaks in the Raman spectrum analysis is above a certain range with respect to the average lattice spacing d _{002 of the} layer. It suppresses the electrode consumption rate during operation, and at the same time forms a material structure that does not cause the separation of fine particles. Therefore, when an electrode plate for plasma etching composed of a glassy carbon material that satisfies the requirement of R ≧ (d ₀₀₂ −3.344) /0.135 is used, operation with a high enching yield is always possible.
[0016]
The electrode plate for plasma etching of the present invention comprising the glassy carbon material having the above properties can be produced as follows. First, in order to achieve high density and high purity of the material, a phenol-based, furan-based, polyimide-based or a thermosetting resin blended with these having a residual carbon ratio of at least 40% or more that has been refined in advance as a raw material is selectively used. . Since these raw material resins are usually in the form of powder or liquid, they are molded into a predetermined plate shape using an optimal molding means such as molding, injection molding or cast molding 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. The calcination carbonization treatment is performed by filling a cured resin molded body in a graphite crucible or in an electric furnace maintained in an inert atmosphere such as nitrogen or argon or a lead hammer furnace while being sandwiched between graphite plates. This is done by heating to ° C. Furthermore, the carbonized fired body is placed in a vacuum furnace capable of atmosphere substitution, and heated to 2000 ° C. while flowing a halogen-based refined gas, and subjected to a high purity treatment.
[0017]
Next, the surface smoothness is increased by wrapping the surface of the fired body. By lapping the surface using a hard tool (lap material) such as abrasive grains and cast iron, the structure of only the surface layer portion of the glassy carbon material can be changed to a desired property. As abrasive grains, for example, metal oxides such as Al ₂ O ₃ abrasive grains, carbides such as SiC abrasive grains, borides such as TiB ₂ abrasive grains, nitrides such as BN ₄ abrasive grains, diamond These abrasive grains are put between a lapping material and a glassy carbon material, and the lapping material and the glassy carbon material are rubbed together for polishing. Abrasive grains sequentially shift from a larger particle diameter 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 that occurs between the abrasive grains and the glassy carbon material. Phenomenon such as generation of force, accumulation of strain energy, and generation of structural defects act in a complex manner to induce a change in surface mechanochemistry. As a result, it can be converted into a glassy carbon material having a surface property that satisfies the requirements of the present invention.
[0018]
You may perform the said surface treatment between the baking carbonization process mentioned above and a highly purified process. Also, whether the through holes for gas flow provided in the electrode plate should be drilled in advance in the resin plate at the resin molding stage in consideration of the dimensional shrinkage during carbonization, or in the resin plate after firing by electric discharge machining. Do one of the following.
[0019]
In the above steps, the desired properties of the glassy carbon can be ensured by appropriately controlling the selection of the refined raw resin, the calcination carbonization temperature, the temperature conditions during the purification treatment, the conditions during the surface polishing, etc. it can.
[0020]
【Example】
Examples of the present invention will be specifically described below in comparison with comparative examples. However, embodiments of the present invention are not limited to these examples.
[0021]
Example 1
(1) Production of electrode plate for plasma etching Phenol and formalin purified by distillation under reduced pressure were condensed according to a conventional method to prepare an initial phenol resin condensate. The raw resin solution was poured into a 400 mm square polypropylene vat, defoamed for 3 hours under a reduced pressure of 10 Torr or less, then placed in an electric oven at 80 ° C. and allowed to stand overnight to form a plate. The molded plate was removed from the bat, heated to 180 ° C. at a rate of 10 ° C. per hour, and subjected to a curing treatment for 24 hours. The molded and hardened resin molded plate is sandwiched between high purity graphite plates and set in an electric furnace. The periphery is encapsulated with graphite powder with a total ash content of less than 100 ppm, and the temperature is raised to 1000 ° C at a rate of 2 ° C / hr. Warmed and calcined.
[0022]
The obtained flat glassy carbon plate with a thickness of 3 mm was drilled with 0.5 mm diameter through-holes at equal intervals of 2 mm, and then abrasive particle size # 800 for 35 minutes, abrasive particle size # 2000 The surface was smoothed by buffing in the order of 25 minutes. Next, the atmosphere was replaced with a vacuum furnace (TP300, manufactured by Tokai High Heat Co., Ltd.), and purified gas of Cl ₂ / He (molar ratio: 5/95) was introduced into the furnace at a supply rate of 5 liters / minute. Then, the temperature was raised to 2000 ° C. and high-purity treatment was performed. This high-purity treated product was subjected to final polishing by buffing in the order of abrasive particle size # 4000 for 25 minutes and abrasive particle size # 8000 for 35 minutes in this order.
[0023]
(2) Measurement of material properties per this manner consists of glassy carbon material manufactured by a plasma etching electrode plate, measure the C (002) from the average diffraction pattern lattice spacing d ₀₀₂ performs X-ray diffraction measurement did. Further, the surface of the electrode plate was irradiated with an argon ion laser beam having a wavelength of 5145 angstroms to perform Raman spectrum analysis, and the relative intensity ratio R in both bands of 1360 ± 100 cm ⁻¹ and 1580 ± 100 cm ⁻¹ was calculated. As a result, the characteristic requirements of the present invention were satisfied.
[0024]
(3) Evaluation of electrode performance Next, this electrode plate was set in a plasma etching apparatus, and the reaction gas: trichloromethane, carrier gas; argon, gas pressure in the reaction chamber; 1 Torr, power frequency: 13.5 MHz Plasma etching of 100 6-inch silicon wafer oxide films was performed. Table 1 shows the thickness reduction (consumption amount) of the electrode plate after the 100-hour treatment and the yield of the 16 MHz DRAM product from the treated wafer in comparison with the properties of the glassy carbon material.
[0025]
Example 2
In the production process of Example 1, the temperature during high-purity treatment was changed to 2100 ° C., and the other conditions were all the same as in Example 1 to produce an electrode plate for plasma etching of a glassy carbon material. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The electrode performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.
[0026]
Example 3
In the manufacturing process of Example 1, the temperature during high-purity treatment was changed to 2100 ° C., and the condition of surface finish polishing after high-purity processing in the manufacturing process was only 45 minutes with abrasive particle size # 6000, all other conditions were An electrode plate for plasma etching of a glassy carbon material was manufactured in the same manner as in Example 1. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.
[0027]
Example 4
In the production process of Example 1, the temperature during high-purity treatment was changed to 2500 ° C., and the condition of surface finish polishing after high-purity treatment in the production process was 45 minutes with abrasive particle size # 3000, and the other conditions were A glassy carbon electrode plate for plasma etching was manufactured under the same conditions as in Example 1. This glassy carbon material satisfied the characteristic requirements of the present invention. The obtained electrode plate was evaluated for performance in the same manner as in Example 1, and the results are listed in Table 1.
[0028]
Example 5
In the production process of Example 1, the temperature during high-purity treatment was changed to 1500 ° C., and all other conditions were the same as in Example 1, and a glassy carbon material plasma etching electrode plate was produced. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.
[0029]
Example 6
In the production process of Example 1, the temperature during high-purity treatment was changed to 3000 ° C., and the surface finish polishing conditions after high-purity treatment were the same as in Example 1 except that the abrasive grain size # 3000 was only 10 minutes. The electrode plate for plasma etching of a glassy carbon material was manufactured according to conditions. The obtained glassy carbon material satisfied the characteristic requirements of the present invention. The performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.
[0030]
Comparative Example 1
In the production process of Example 1, polishing was performed for 25 minutes at abrasive particle size # 4000 and 35 minutes at # 8000 in the surface treatment conditions after 1000 ° C. treatment, and finish polishing after high purity treatment was stopped. Were the same as in Example 1 to produce an electrode plate for glass etching of glassy carbon material. The obtained glassy carbon material deviated from the characteristic requirements of the present invention. The performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.
[0031]
Comparative Example 2
In the production process of Example 1, the temperature during high-purity treatment was changed to 1200 ° C., and all other conditions were the same as in Example 1 to produce an electrode plate for plasma etching made of a glassy carbon material. The obtained glassy carbon material deviated from the characteristic requirements of the present invention. The performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.
[0032]
Comparative Example 3
In the manufacturing process of Example 1, the temperature during the high-purity treatment was changed to 2500 ° C., the finish polishing after the high-purity treatment was stopped, and all other conditions were the same as in Example 1, and plasma etching made of a glassy carbon material An electrode plate was manufactured. The obtained glassy carbon material deviated from the characteristic requirements of the present invention. The performance of this electrode plate was evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0033]
[Table 1]

[0034]
From the results in Table 1, it can be seen that the electrode plates made of the glassy carbon material according to the example satisfying the characteristic requirements of the present invention have less electrode consumption and a higher product yield than the comparative example products. However, and glassy embodiment relative intensity ratio R is out of the range of 1.0 to 2.0 carbon material 6, exemplary average lattice spacing d ₀₀₂ is out of the range of 3.40 to 3.60 Å Example 5 , It was observed that the yield of the product decreased slightly due to the dropout of fine particles.
[0035]
【The invention's effect】
As described above, the properties of average lattice spacing d ₀₀₂ of the present invention in accordance if the relative intensity ratio of two specific bands zone appearing by Raman spectroscopy and X-ray diffraction by the obtained graphite hexagonal plane layer is in a specific range By selecting this glassy carbon material, it is possible to provide an electrode plate for plasma etching that is excellent in product yield with little etching consumption and no generation of fine particles. Therefore, a stable etching process is always guaranteed and the life of the electrode plate can be greatly extended.

Claims (3)

Spectral intensity (IA) appearing in the band region of 1360 ± 100 cm ⁻¹ and spectral intensity appearing in the band region of 1580 ± 100 cm ⁻¹ (IB) in Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 angstroms Relative strength ratio R (IA / IB) and average lattice spacing d ₀₀₂ (unit: angstrom) of graphite hexagonal mesh layer are made of glassy carbon material satisfying the relationship of the following formula (1) An electrode plate for plasma etching.
R ≧ (d ₀₀₂ −3.344) /0.135 (1) The electrode plate for plasma etching according to claim 1, comprising a glassy carbon material having a relative intensity ratio R in the range of 1.0 to 2.0. 3. The electrode plate for plasma etching according to claim 1, wherein the graphite hexagonal mesh layer has an average lattice spacing d ₀₀₂ made of a glassy carbon material in a range of 3.40 to 3.60 angstroms.