JP3447023B2 - Electrode plate for plasma etching - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for manufacturing a semiconductor integrated circuit such as an IC or an LSI by drying a polysilicon, an oxide film or a nitride film on a wafer surface by plasma. The present invention relates to an electrode plate for plasma etching used for etching. 2. Description of the Related Art In plasma etching, a reactive gas (C, H, F atom-containing gas) is introduced into an RIE (Reactive Ion Etching) apparatus provided with a pair of parallel plane electrodes while a high frequency is applied between the electrodes. This is a processing step of forming a high-precision fine circuit pattern by applying electric power to discharge and etching a non-photoresist part using generated gas plasma. The planar electrodes used in this plasma etching process need to have excellent conductivity, high purity that does not contaminate the wafer, and chemical stability that is not easily etched, and currently meet these material requirements. As such, an electrode plate made of glassy carbon is useful. [0003] A glassy carbon material is a vitreous hard carbonaceous material having a macroscopically non-porous three-dimensional network structure obtained by carbonizing a thermosetting resin and having high strength, chemical stability, and gas resistance. Excellent properties such as permeability, abrasion resistance, self-lubricating property, and robustness, and low impurity content.Especially, minute particles that cause soiling of the wafer during the plasma etching process are separated from the tissue. There are difficult advantages.
However, recently, the degree of integration of semiconductors has been increasing more and more, and therefore strict requirements have been placed on the electrode material for plasma etching to reduce the number level and the degree of wear of particles adhering to the wafer surface. [0004] For this reason, many proposals have been made regarding improvement of the material of a glassy carbon electrode for plasma etching. For example, assuming that the purity, porosity, pore diameter, crystal structure and other material properties are the targets, the porosity is 0.0002 to 0.0020%, the crystallite is not detected by X-ray diffraction, and the impurity content is A carbon member for a plasma device made of a glassy carbon material of 5 ppm or less (Japanese Patent Application Laid-Open No. 3-33007) has a structure having a maximum porosity of 1 μm or less, an average porosity 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 Application Laid-Open No. 3-119723), a plate made of high-purity glassy carbon and having a thickness of 2 mm or more;
An electrode plate for plasma etching having substantially no grain boundaries on the surface and internal structure and having a maximum pore diameter of 1 μm or less (Japanese Patent Laid-Open No. 3-285086);
When the metal impurities are 2 ppm or less, the total sulfur content is 30 ppm or less, the crystal characteristics are (002) 0.375 nm or less, and the crystallite (00
2) An electrode plate for plasma etching made of glassy carbon having a size of 1.3 nm or more, a material property of specific gravity of 1.50 or more, and a bending strength of 1100 kg / cm ² or more (JP-A-5-320955) , The lattice constant Co (002) is 6.990.
An electrode plate for plasma etching made of glassy carbon having a crystal of Å or less (Japanese Patent Laid-Open No. 6-128761).
An electrode plate for plasma etching made of glassy carbon having a maximum of 6 μm or less (Japanese Patent Application Laid-Open No. 6-128762) has been proposed. [0005] Further, as a material mainly composed of a raw material resin, an electrode plate for plasma etching made of a glassy carbon material produced from a phenol resin and a polycarbodiimide resin (JP-A-5-347276), Electrode plate for plasma etching made of glassy carbon material manufactured from resin (JP-A-5-3472)
No. 78 gazette). Further, in recent years, the glassy carbon electrode has a high purity because it eliminates the problem that the carbon atoms are sputtered by plasma to contaminate the wafer and that the fine particles fall off due to the structure defect inside the material. In addition, as an electrode material for plasma etching that does not cause chemical stability and tissue destruction, a material composed of silicon single crystal has been proposed (JP-A-6-177076 and JP-A-6-177076).
-283469). However, the productivity of large-sized disks is poor because the Si single crystal is restricted by the pulling size, and for example, as in the invention described in JP-A-6-283469, the disk portion of Si single crystal and In the case of a structure in which the carbon ring portions are joined, there is a concern that strain deformation may occur during the use process due to the difference in thermal expansion coefficient between the two materials. SUMMARY OF THE INVENTION The inventors of the present invention have been conducting various researches on the improvement of the structure of the glassy carbon material constituting the electrode plate for plasma etching, and have found that the structure of the glassy carbon material has not been improved. It has been confirmed that, when a certain amount of Si is uniformly dispersed and contained, the generation of particles is suppressed, the electrode consumption rate during the etching process is reduced, and the consumption proceeds extremely uniformly. [0008] The present invention has been developed based on the above findings, and its object is to reduce electrode wear,
An object of the present invention is to provide an electrode plate for plasma etching that can perform a uniform dry etching process without generating fine particles. In order to achieve the above object, an electrode plate for plasma etching according to the present invention comprises -O
Atomic level Si obtained by calcining and carbonizing a molded article of a thermosetting resin cross-linked with —Si—O— in a glassy carbon structure having a uniform continuous phase in a range of 0.1 to 10% by weight. It is characterized in that it is composed of a Si-containing glassy carbon material having a texture property of being dispersed and contained. The Si-containing glassy carbon material constituting the present invention is preferably a composite structure in which the Si component dispersed and contained in the glassy carbon structure is distributed at the atomic level, particularly -O-Si-O. -An excellent effect is exhibited when the molded product of the thermosetting resin cross-linked in-is obtained by calcining and carbonizing, and has a structural property in which atomic-level Si is distributed as a uniform continuous phase in a glassy carbon structure. You. The microstructure in which Si at the atomic level is distributed as a uniform continuous phase in the glassy carbon microstructure means that there is substantially no grain boundary between Si and C, and the microstructure is determined by observation with a transmission electron microscope (TEM).
Refers to a tissue state in which the i component cannot be identified. Si dispersed in glassy carbon structure
Is a component that functions to strengthen the fragile glassy carbon structure to prevent the particles from falling off, and to ensure a uniform and low progress rate of etching consumption. The content is 0.1 to 10% by weight. , Preferably in the range of 2 to 8% by weight. If the Si content is less than 0.1% by weight, it is not possible to reduce the amount of electrode consumption, and if it exceeds 10% by weight, it is not possible to maintain an atomic Si dispersion state, but rather, the generation of particles increases. This can cause The electrode plate for plasma etching of the present invention comprising the Si-containing glassy carbon material having the above-mentioned structural properties comprises a thermosetting resin and a hydrolyzate of a Si alkoxide having a single Si atom in one molecule. After stirring and mixing in an organic solvent, the gelled product obtained by the cross-linking reaction is cured and molded into a plate, and then the plate is molded under a non-oxidizing atmosphere for 800 minutes.
It can be produced by a method of performing a carbonization treatment in a temperature range of not less than ° C. The specific manufacturing process is as follows. The thermosetting resin used as the raw material of the glassy carbon includes, for example, a phenol resin, a furan resin,
Polyimide-based resins, polycarbodiimide-based resins, polyacrylonitrile-based resins, pyrene-phenanthrene-based resins, polyvinyl chloride-based resins, epoxy-based resins, and mixed resins thereof are used. In particular, a phenol resin, a furan-based resin or a mixed resin thereof having a residual carbon ratio of 45% by weight or more when the resin is fired at a temperature of 800 ° C. in a non-oxidizing atmosphere is preferably used. The Si alkoxide having a single Si atom in one molecule selected and used as the Si source is represented by the general formula Si
(OR) _n or R _n Si (OR) _n (where R represents an alkyl group or an aryl group, and n represents an integer of 1 or more). Compounds such as polysilane, polysiloxane, and polysilazane to which Si atoms are bonded are not included. Examples of usable Si alkoxides having a single Si atom include methoxysilane, ethoxysilane, butoxysilane, propoxysilane, isopropoxysilane, diethoxysilane, dibutoxysilane, dipropoxysilane, trimethoxysilane, and triethoxysilane. , Tributoxysilane, tripropoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrapropoxysilane, trimethylmethoxysilane, trimethylethoxysilane, tri-n-propylmethoxysilane, tri-n-propylethoxysilane, tri- -N-butylmethoxysilane, tri-iso-butylmethoxysilane, tricyclohexylmethoxysilane, tricyclohexylethoxysilane, bis (2-ethylhexyl)
Examples thereof include dimethoxysilane and bis (2-ethylhexyl) diethoxysilane. However, for the purpose of the present invention, low-molecular-weight tetramethoxysilane [Si (OCH ₃ ) ₄ ] or tetraethoxysilane [Si (OC
₂ H _{5) 4]} are preferred, particularly the latter tetraethoxysilane are preferably used. Si alkoxide having a single Si atom in one molecule (hereinafter simply referred to as "Si alkoxide")
Is added so as to have a concentration of 50% by volume or less with respect to the organic solvent, and an appropriate amount of water (1 to
(Equivalent to 2 mol) and hydrolyze, and mixed with a thermosetting resin in an organic solvent. It is preferable that the Si alkoxide and the thermosetting resin are each added to an anhydrous alcohol-based organic solvent, sufficiently stirred, and then subjected to an ultrasonic dispersion treatment and then mixed. Sequential application makes it possible to effectively dissolve aggregated constituent molecules. For this reason, the reaction and agglomeration of the Si alkoxide in the subsequent operation stage are suppressed, and a stable unimolecular dispersion state is maintained. The mixing of the Si alkoxide and the thermosetting resin is performed by a method in which the hydrolyzed Si alkoxide solution is gradually added to the thermosetting resin liquid while stirring.
At this time, the addition amount of the thermosetting resin is such that the Si content in the glassy carbon structure is finally 0.1 to 10% by weight.
Adjust the amount ratio so that At the time of mixing, if the solution is alkaline, polycondensation proceeds rapidly to form a spherical polymer. Therefore, it is preferable to adjust the pH of the solution to an acidic side using, for example, an anhydrous alcohol-soluble organic acid. When the Si alkoxide solution and the thermosetting resin liquid are mixed, a cross-linking reaction occurs between the C-OH group in the thermosetting resin and the silanol group (Si-OH) of the hydrolyzed Si alkoxide, and gradually the gel is formed. Become Since this crosslinking reaction is much faster than the dehydration condensation reaction between silanols, a gelled product in a state where the thermosetting resin is easily crosslinked with -O-Si-O- can be obtained. Therefore, the molded article is poured into a mold before the mixture of the Si alkoxide solution and the thermosetting resin liquid gels, and if necessary, subjected to vacuum defoaming treatment, and then heated from room temperature to 70 ° C. It is preferably formed by a method of curing simultaneously with the formation. As the molding means, an appropriate method such as centrifugal molding, injection molding, transfer molding, compression molding, and lamination molding can be adopted. Then, the cured molded body is packed in a graphite crucible or sandwiched between graphite plates, and then packed in an electric furnace or a lead hammer furnace kept in an inert atmosphere of nitrogen, argon or the like, and heated to a temperature of 800 ° C. or more. Range, preferably 1000-
A calcining treatment is performed in a temperature range of 2500 ° C. to convert the thermosetting resin component into glassy carbon. The deoxygenation reaction proceeds in this calcined carbonization stage, and Si has a texture characteristic of being distributed as a uniform continuous phase at the atomic level in the glassy carbon structure in the range of 0.1 to 10% by weight. The small through-holes provided in the electrode plate are formed in the compact before firing and carbonization in consideration of the dimensional shrinkage ratio during carbonization in advance, or are formed in the carbon plate after firing by electric discharge machining. This can be done in either way. The electrode plate for plasma etching according to the present invention comprises:
A composite composition containing Si in a glassy carbon structure in a range of 0.1 to 10% by weight, particularly preferably -O-Si
Atomic level Si obtained by calcining and carbonizing a molded product of a thermosetting resin in which —O— has been crosslinked is provided with a structural property in which the Si at an atomic level is distributed as a uniform continuous phase in a glassy carbon structure.
This structure characteristic is different from the structure in which the Si component is dispersed in the state of fine particles, and exhibits an alloy-like continuous solid solution phase in which there is no grain boundary between Si and C in the structure. Although there is no substantial difference from the single structure, microscopically, a part of C in the glassy carbon structure is Si
To form a unique composite morphology having a continuous phase bonded by -C-Si-C-. When a glassy carbon plate is used as an electrode for plasma etching, the degree of consumption varies slightly depending on the purity, crystal structure, surface condition, etc. of the glassy carbon used. The condition is that the tissue particles become spherical, and the generation of particles during use and unevenness of the etching rate occur when such tissue particles are spherically consumed in large units or when there is a local heterogeneous part in the tissue. easy. In the electrode plate for plasma etching of the present invention, as described above, a certain amount of Si is distributed in the glassy carbon structure as a uniform continuous phase at the atomic level, and this Si fills and bonds fine voids and is consumed. It functions to effectively suppress the phenomenon that the glassy carbon structure becomes spherical grains in the process. Based on this effect, a stable etching process with a uniform consumption rate can be performed in a state where the degree of wear is small and no particles are generated. 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. Examples 1 to 5 and Comparative Examples 1 to 2 Tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] was dissolved in anhydrous ethanol so as to have a concentration of 50% by volume, and stirred with a stirrer for 30 minutes. After that, dispersion treatment was performed for 2 hours by an ultrasonic vibration device. To this solution, 0.03 mol equivalent of anhydrous acetic acid and 1 mol equivalent of water were added dropwise to tetraethoxysilane, and the mixture was stirred and mixed with a stirrer for 1 hour to hydrolyze tetraethoxysilane. Then, while stirring the hydrolyzed tetraethoxysilane, the phenol resin liquid previously dissolved in anhydrous ethanol, stirred for 30 minutes with a stirrer, and then subjected to a dispersion treatment for 2 hours by an ultrasonic vibrator was gradually added. Stir for 1 hour with a stirrer and mix until uniform. The mixed solution was poured into a mold, defoamed in a vacuum device, and heated from room temperature to 70 ° C. to harden a gel formed by the crosslinking reaction. The obtained cured molded body was transferred to a heating furnace maintained in a nitrogen atmosphere, and heated to 2000 ° C. at a rate of 10 ° C./hr to carbonize by firing. In this way, the Si-containing glassy carbon material having a different Si content (diameter 280 mm, thickness 4
mm). Through holes having a diameter of 0.5 mm are formed at intervals of 2 mm in each of the manufactured plate-shaped Si-containing glassy carbonaceous materials by an electric discharge machining method, and then the surface is buff-polished smoothly using an abrasive particle size of # 800. Thus, an electrode plate for plasma etching was obtained. Next, each of the manufactured electrode plates was set in a plasma etching apparatus, and the reaction gas was 8 inches under the following conditions: CF ₄ , carrier gas; Ar, gas pressure in the reaction chamber: 1 Torr, power supply frequency: 13.5 MHz. Was subjected to plasma etching of the silicon wafer oxide film, and the thickness reduction of the electrode plate after 100 hours was measured. Further, the state of generation of particles and the state of etching of the wafer were observed and evaluated, and the results are shown in Table 1 in comparison with the Si content in the glassy carbon structure. In addition, the generation state of the particles was 0.3 μm which fell on the wafer surface during one etching.
The determination was made based on the presence or absence of the above carbon particles. Comparative Example 3 An electrode plate for plasma etching made of a glassy carbon material was produced according to Example 1 using only phenol resin as a raw material without mixing tetraethoxysilane. Table 1 also shows the results of etching the electrode plate in the same manner as in Example 1. [Table 1] From the results shown in Table 1, the amount of plasma etching consumption of the electrode plates according to the examples was as small as 0.5 mm or less, no particles were generated, and the electrode consumption was uniform. On the other hand, a glassy carbon material having a Si content of less than 0.1 causes a large amount of electrode consumption, and a comparative example 2 having a Si content of 12% by weight generates particles and nonuniform electrode consumption. It was recognized that. As described above, according to the present invention, by selecting a Si-containing glassy carbon material in which a certain amount of Si is dispersed and contained in a glassy carbon structure, consumption is reduced and particles are generated. A high-performance electrode plate for plasma etching that can be operated at a uniform etching rate without any problem can be provided. Therefore, stable etching is ensured, and the useful life of the electrode plate is greatly extended, and the number of replacements is reduced. Therefore, the effect of reducing the etching running cost is brought about.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Motohiro Yamamoto, Inventor 1-2-3 Kitaaoyama, Minato-ku, Tokyo Tokai Carbon Co., Ltd. (56) References JP-A-6-64961 (JP, A) JP-A-2 JP-A-26867 (JP, A) JP-A-5-347276 (JP, A) JP-A-5-123923 (JP, A) JP-A-59-162175 (JP, A) JP-A-56-44732 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/3065 C23F 4/00

Claims (1)

(57) [Claims 1] Thermosetting crosslinked with -O-Si-O-
Atomic level S obtained by firing and carbonizing a resin molded product
An electrode plate for plasma etching, wherein i is made of a Si-containing glassy carbon material having a texture characteristic of being dispersed and contained as a uniform continuous phase in a range of 0.1 to 10% by weight in a glassy carbon structure .