JP3262696B2 - Silica glass member having glassy carbon coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silica glass member used in a semiconductor device manufacturing process, and more particularly to a silica glass member used in a dry etching or sputtering film forming process using plasma.

[0002]

Conventionally, in the semiconductor industry, a metal material is sputtered with plasma ions to form a metal film on a semiconductor element, or conversely, a pattern is formed by sputter etching the surface of a semiconductor element. Alternatively, various types of plasma are used in various ways such as flattening or cleaning the surface of the element. Among them, plasma etching and sputter etching (generally called dry etching)
However, there is a problem that various jigs used are also etched at the same time, and fine powder is generated therefrom, which contaminates the semiconductor element. Therefore, the use of vitreous carbon, which is known as a substance that is dense and hard to generate dust, can be considered. For example, Japanese Patent Application Laid-Open Nos. 62-252942 and 62-170762 disclose an electrode for plasma etching, Carbon No. 51 (1967) p1
No. 7, the use of glassy carbon as a jig for semiconductor processing such as a boat, a crucible, a wafer susceptor, etc. is being studied. However, glassy carbon is expensive compared to silica glass and has poor workability, making it difficult to form a member having a complicated shape.
As shown in Japanese Patent No. 16225, a jig having a complicated shape is formed of a base material having excellent workability such as isotropic carbon, and a simple portion is formed of glassy carbon and then joined.
Partially glassy carbon is used. At present, it is impossible to use glass-like carbon in its limited form or in partial use, making full use of the properties of glassy carbon.

[0003]

The inventors of the present invention have conducted intensive studies for the effective use of glassy carbon. As a result, the present inventors have found that conventional silica glass members, especially substrates for jigs for manufacturing semiconductor devices, have not been developed. By applying a glassy carbon material on the surface and carbonizing it, a uniform glassy carbon film can be formed even if it has a complicated shape, and it has the surface characteristics of glassy carbon and is not used for semiconductor production. A member is obtained, especially a silica glass substrate treated with a chemical treatment solution, the surface is roughened, then a glassy carbon material is applied, and then carbonized to form a glass with uniform and sufficient adhesive strength The inventors have found that a member having a carbon coating can be obtained, and have completed the present invention. That is,

An object of the present invention is to provide a silica glass member coated with glassy carbon.

The present invention relates to a silica glass member having a high surface hardness, plasma resistance and no dust generation, which is obtained by coating a glassy carbon material on the surface of a silica glass member having a rough surface after being treated with a chemical treatment solution. An object is to provide a member.

An object of the present invention is to provide a silica glass jig coated with glassy carbon for manufacturing a semiconductor device.

[0007]

Means for Solving the Problems] To achieve the above object the present invention provides the plasma processing silica glass member having a surface covered with glassy carbon silica glass substrate, the
Hydrogen fluoride, ammonium fluoride
Treated with a surface treatment solution consisting of aluminum , acetic acid, and water to form a surface with a centerline average roughness (R) of 0.5 to 2.0 μm
Is a glassy carbon layer thickness 0.5~8μ thereon
and m is coated with a silica glass member for plasma processing. The glassy carbon,
For example, “carbon” No. 45 (1966), pp. 19-25, a thermosetting resin such as a furan resin, a phenol resin or a co-condensation resin thereof, particularly preferably furfural or a phenol co-condensation resin, which is used as a raw material. A carbon having a glassy structure formed by carbonizing after being applied to a glass substrate. The carbonization is performed by heating to a carbonization temperature in an inert gas atmosphere.As the inert gas atmosphere, an argon atmosphere is used.
As the carbonization temperature, heating at a temperature lower than the deformation temperature of the silica glass and about 1100 ° C. or lower is preferable. A glassy carbon coating is formed on the surface of the silica glass substrate by the carbonization, and its thickness is preferably in the range of 0.5 μm to 8 μm. When the thickness of the glassy carbon coating is 0.5 μm or less, the properties of glassy carbon such as plasma resistance, high surface hardness, little generation of particles and impurities cannot be sufficiently exhibited, and the thickness of the glassy carbon coating is 8 μm. Is not practical because a coating step and a carbonizing step need to be repeated many times. The coating is formed by coating a silica glass substrate prepared by glasswork, or by coating each base material before work with a raw material of glassy carbon and then carbonizing. The coating is easily peeled off, and the film thickness is limited to about 2 μm. In order to form a good glassy carbon film, the surface of the silica glass substrate is preferably roughened. In particular, the center line average roughness (R
_a ) It is preferable to roughen in the range of 0.5 to 2.0 μm. If the surface roughness is less than 0.5 μm in the center line average roughness, the roughening effect is not obtained, and the treatment with the surface roughness exceeding 2 μm damages the silica glass substrate and lowers the strength.

As a method for roughening the surface of the silica glass substrate, a sand blasting method or a chemical treatment method can be adopted. In the sand blasting method, cracks are easily generated in the silica glass substrate, and contaminants are taken therein. It is not suitable because it can be released during the processing of semiconductor products and contaminate the semiconductor elements. On the other hand, the chemical treatment method is preferable because contaminants can be easily removed by washing after the treatment. In particular, since the surface treatment liquid composed of hydrogen fluoride, ammonium fluoride, acetic acid and water does not contain substances that contaminate semiconductor elements such as metal elements and alkali elements, it is used as a treatment liquid for roughening the surface of a silica glass substrate. preferable. The component ratio of the surface treatment liquid is such that the content of acetic acid is 10% by weight or more, the content of water is 50% by weight or less, the total content of hydrogen fluoride and ammonium fluoride is 25% or more, and 1 mole of ammonium fluoride. The content of hydrogen fluoride is 0.2 to
Water is in a range of 30 parts or more with respect to 70 parts of hydrogen fluoride at a ratio of 15 mol. The surface treatment liquid may be a mixture containing a precipitate. The precipitate is preferable because the deterioration of the surface treatment solution is compensated for by re-dissolution. If the amount of hydrogen fluoride exceeds 15 mols per 1 mol of ammonium fluoride in the surface treatment solution, the surface is not roughened. If the amount is less than 0.2 mol, the etching progresses slowly, and the surface is roughened even if the surface is roughened. Is too shallow to be practical. Further, when the total content of ammonium fluoride and hydrogen fluoride is less than 25% by weight, surface roughening hardly occurs. It is better to use a large amount of water for economic reasons of the surface treatment solution. However, if the amount of water is 50% by weight or more, the growth of the rough surface is slow, and the amount of the precipitate in the treatment solution is reduced. In the presence of this water,
The balance of each chemical substance can be carefully adjusted, and the size and number of the precipitates, the growth rate, and the etching rate can be arbitrarily changed. In addition to these components, the surface treatment liquid must contain acetic acid. By containing acetic acid, the surface of the silica glass substrate can be satisfactorily roughened. If the amount of the acetic acid is less than 10% by weight, the formation of irregularities on the surface of the silica glass is poor, and the surface is not sufficiently roughened. Ammonium hydrogen fluoride, which is a reagent having a molar ratio of hydrogen fluoride to ammonium fluoride of 1: 1 in the surface treatment solution, is preferred because it is easy to handle.

As a method of treating the silica glass substrate, the member may be immersed in the above surface treatment solution for 2 to 6 hours, preferably 3 to 4 hours. As a result, uniform irregularities are formed on the surface of the silica glass member, and the appearance becomes a white rough surface.

[0010] A thermosetting resin liquid such as furfural resin, phenol resin, or a co-condensation resin thereof is applied to the silica glass substrate having the roughened surface, and after the resin liquid is thermally solidified, it is subjected to heat treatment. Heat treatment in active gas to carbonize.
Thus, the glassy carbon is uniformly coated on the surface of the silica glass substrate. The coating does not need to cover the entire surface of the silica glass substrate, but it is necessary to cover at least a portion exposed to the plasma.

[0011]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 FIG. 1 is a diagram of a plasma etching apparatus having a silica glass chamber and a silica glass wafer support jig. In FIG. 1, 1 is a semiconductor wafer, 2 is a silica glass chamber, 3 is a silica glass wafer boat, 4 is a glassy carbon coating, 5 is a gas exhaust port, 6 is a gas inlet, and 7 is an RF power source (high frequency power source). It is. The silica glass wafer support jig 3 is first processed into a predetermined shape with silica glass, and then the contaminants in the processed portion are removed by etching with hydrofluoric acid, and fine irregularities on the surface are melted and smoothed with a flame. It was immersed in a treatment solution of 22.1% by weight of hydrogen fluoride, 20.4% by weight of ammonium fluoride, 35.4% by weight of acetic acid and 22.1% by weight of pure water for 4 hours to obtain a center line average roughness. A jig base material having _{a Ra of} 1.1 μm was obtained, and a co-condensation resin of furfural and phenol was applied thereto, solidified, heated to a maximum of 1100 ° C. in an argon gas atmosphere, and carbonized to obtain the aforementioned co-condensation. The resin was produced as glassy carbon 4. The semiconductor wafer 1 was placed on the jig 3 obtained, introduced into a silica glass chamber, and subjected to plasma etching using a halogenated carbon-based gas such as CF _4. The surface of the glass did not lose its gloss. Processing semiconductor wafer 1
There was no particle contamination.

Example 2 In order to confirm the sputter resistance of the silica glass wafer supporting jig 3 manufactured in Example 1 against inert ions, the RF sputtering rate of argon gas was measured for a small piece thereof. As a result, the sputter rate of the small piece was about one-fifth that of aluminum oxide, which is a representative of a material having good sputter resistance. On the other hand, when the above test was carried out on a small piece of silica glass for reference, the sputtering rate was about 5 times that of aluminum oxide.

Embodiment 3 FIG. 2 shows a schematic view of a reactive ion etching apparatus. In FIG. 2, 1 is a semiconductor wafer, 2 is a silica glass chamber, 9 is a silica glass wafer support jig, 4 is a glassy carbon film, 5 is a gas exhaust port, 6 is a gas inlet, 10 is an anode, 11 Indicates a cathode, and 12 indicates plasma.
A chamber 8 for reactive ion etching (RIE) of silica using a mixed gas of hydrogen gas, carbon tetrachloride gas or the like containing CF ₄ as a main component is made of silica glass, and 23.6% by weight of hydrogen fluoride and fluorine are used. Ammonium iodide 17.4
4% by weight of acetic acid, 35.4% by weight of pure water and 23.6% by weight of pure water for 4 hours to roughen the inner surface. The inner surface of the chamber 8 after the treatment was uniform white, and the surface roughness was center line average roughness _Ra = 0.9 μm. A co-condensation resin of furfural and phenol is applied to the inside of the chamber 8 in the same manner as in Example 1, solidified, heated to a maximum of 1100 ° C. in an argon gas atmosphere, and carbonized to form a glassy carbon 4 coating. Was formed. The obtained coating 4 had a uniform thickness though a small amount of pinholes were observed. A practical test was performed using the chamber having a glassy carbon coating on the inside as a chamber for RIE. As a result, favorable etching could be performed without damage to the chamber due to plasma.

[0014]

The silica glass member of the present invention has a glassy carbon film on its surface, has a high surface hardness, and has a stable dust-free silica that is not sputtered or roughened by plasma. It is a glass member.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a plasma etching apparatus equipped with a silica glass jig in which a wafer support is coated with glassy carbon.

FIG. 2 is a schematic diagram of a reactive ion etching apparatus having a silica glass chamber in which the inside of the chamber is coated with glassy carbon.

[Explanation of symbols]

 Reference Signs List 1 semiconductor wafer 2 silica glass chamber 3 silica glass wafer boat 4 glassy carbon coating 5 gas exhaust port 6 gas inlet 7 RF power supply 8 chamber for reactive ion etching (RIE) 9 silica glass wafer support jig 10 anode 11 Cathode 12 Plasma

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Dietma Hermann Germany 63801 Kleinstheim Reinhard-Helaus Ring 29 Heraus-Kwarzgrass-Gämbeher Berich Halplitter (56) References JP-A-7 JP-A-199183 (JP, A) JP-A-3-187954 (JP, A) JP-A-1-305835 (JP, A) JP-A-7-315587 (JP, A) JP-A-7-267679 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 H01L 21/302 H01L 21/3065 C03C 15/00-23/00 JICST file (JOIS)

Claims (1)

(57) [Claims] In a silica glass member for plasma treatment in which the surface of a silica glass substrate is coated with glassy carbon, the surface of the silica glass substrate is formed of hydrogen fluoride, fluoride fluoride, or the like.
Treated with a surface treatment solution consisting of ammonium, acetic acid and water, the surface roughness being 0.5 to 2.0 μm in terms of center line average roughness (R).
It is formed on a glassy carbon layer thickness of 0.5 thereon
A silica glass member for plasma processing, wherein the silica glass member is coated to a thickness of 8 μm.