JPH07286269A - Carbon target for forming thin film and its production - Google Patents

Abstract

PURPOSE:To provide a high-purity carbon target for forming a thin film capable of eliminating the difficult point of the conventional technique and without generating an abnormal discharge or a powder causing pollution. CONSTITUTION:This carbon target for forming a thin film is formed by the vitreous carbon produced from a polycarbodiimide resin. The target is produced by forming a polycarbodiimide resin or a composition consisting essentially of polycarbodiimide resin into an appropriate shape and carbonizing the shaped material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon target material for forming a thin film, and more specifically, to a hard disk, a semiconductor, a magnetic head, glass, metal, etc., an abrasion resistant layer, an antioxidant layer, a moisture resistant layer, The present invention relates to a carbon target material for forming a carbon thin film, which is applicable as a weather resistant layer, an antireflection layer, and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, the demand for thin film technology has become more and more stringent with the progress of computer technology and the like. Among them, as a wear resistant layer, an antioxidant layer, a moisture resistant layer, a weather resistant layer and an antireflection layer, etc. There are great expectations for applicable carbon target materials for forming carbon thin films.

A magnetic disk can be given as an example of a field in which the above-mentioned thin film technology is adopted. That is, a random-accessible disk-shaped magnetic disk is widely used as a recording medium of the present computers and the like. Among them, excellent responsiveness, large storage capacity, excellent storability, and high reliability. Since it is expensive, aluminum (A
l) Magnetic disks using hard materials such as alloy plates, glass plates and plastic plates are often used.

Such a magnetic disk is used while rotating, and when recording / reproducing is performed on the magnetic disk, the magnetic disk is stationary before the operation is started. However, when the operation is started, the magnetic disk rotates at a high speed, the magnetic layer surface and the magnetic head face each other with a minute gap therebetween, and when the operation is completed, the two are brought into contact with each other again. It is generally adopted and this method is called a contact start / stop method (hereinafter abbreviated as CSS method).

As described above, in the CSS method, the magnetic layer surface and the magnetic head are repeatedly brought into contact with each other at the start and end of the operation, so that the frictional force generated between them causes the magnetic head and the magnetic disk to wear. Cause
Alternatively, if dust or powder that has fallen off the magnetic layer adheres to the magnetic disk, head crush may occur, or a magnetic head may suddenly collide with the magnetic layer surface. It is not preferable from the viewpoint of reproduction reliability and durability.

Therefore, conventionally, it has been studied to form a carbon protective film having a thickness of about several hundreds nm on the surface of the magnetic recording medium to improve durability. Usually, this protective film is
A film is formed by sputtering using a carbon sintered body as a target material, and the carbon sintered body used here is a mixture of natural graphite, artificial graphite and the like, pitch, resin, etc., molded, and then carbonized by firing. , Is a graphitized material and is called a graphite material.

[0007]

However, the carbon sintered body (graphite material) that is generally used has many pores with a diameter of 0.1 μm or more on the surface thereof, and this is a target material. When used as a material, swelling (which looks like a buried substance) is formed on the surface of the target material due to a component having a bulk specific gravity lower than that of the target material, and the pores and such swelling exist. When the smoothness of the target material surface is lost, abnormal discharge occurs in those portions during sputtering, a part of the graphite material is destroyed, and carbon powder with a size of several tens nm to several mm flies into the chamber, There is a problem that the sputtered film is contaminated and the product yield is reduced.

Of course, the above-mentioned abnormal discharge has become a serious problem in advanced technical fields such as semiconductors and hard disks. Therefore, abnormal discharge may occur to generate powders or the like which may lead to contamination. It has been desired to develop a high-purity carbon target material for forming a thin film, which is free of defects.

The present invention has been made in view of the problems of the prior art as described above, and its purpose is to provide a carbon target for forming a thin film having good physical properties suitable for sputtering as described above. Is to provide wood.

[0010]

The constitution of the carbon target adopted by the present invention to solve the above-mentioned problems is characterized in that it is made of glassy carbon produced from a polycarbodiimide resin as a raw material. The composition of the manufacturing method is characterized in that a polycarbodiimide resin or a composition mainly composed of a polycarbodiimide resin is molded into an appropriate shape, and then the molded product is carbonized to obtain glassy carbon.

The present invention will be described in detail below.

The above-mentioned polycarbodiimide resin itself is well-known or can be produced in the same manner as well-known ones {US Pat. No. 2,941,95.
6, Japanese Patent Publication No. 47-33279, J. Or
g. Chem. , 28 , 2069-2075 (196
3) Chemical Review l98l, vo
l. 8l. No. 4, 619 to 62l, etc.}, for example, it can be easily produced by a condensation reaction involving decarbonization of an organic diisocyanate in the presence of a carbodiimidization catalyst.

The organic diisocyanate used for producing the above polycarbodiimide resin may be of any type such as aliphatic type, alicyclic type, aromatic type, aromatic-aliphatic type, and the like. Used alone, or
You may use it in combination of 2 or more type.

Specifically, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-
Mixtures of tolylene diisocyanate and 2,6-tolylene diisocyanate, crude tolylene diisocyanate, xylene diisocyanate, m-phenyl diisocyanate, naphthylene-1,5-diisocyanate, 4,4.
-Biphenylene diisocyanate, 3,3, -dimethoxy-4,4, -biphenyl diisocyanate, or a mixture thereof can be exemplified as the organic diisocyanate.

Thus, the polycarbodiimide resin used in the present invention has the following formula -RNN = C = N- (wherein R in the formula represents an organic diisocyanate residue).
The homopolymers or copolymers of at least 1 type of repeating unit represented by

As R in the above formula, which is an organic diisocyanate residue, an aromatic diisocyanate residue is particularly preferable (here, the organic diisocyanate residue is obtained by removing two isocyanate groups (NCO) from the organic diisocyanate molecule). I say the rest). The following can be mentioned as specific examples of such a polycarbodiimide resin.

[Chemical 1]

In each of the above formulas, n is 10 to 10,0.
It is within the range of 00, preferably within the range of 50 to 5,000, and the end of the polycarbodiimide resin may be blocked with monoisocyanate or the like, thus sealing the end of the polycarbodiimide. Examples of the monoisocyanate for controlling the molecular weight thereof include phenyl isocyanate, (ortho, meta, para) -tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate and methyl isocyanate.

The above polycarbodiimide resin can be obtained as a solution as it is or as a powder precipitated from the solution, and the polycarbodiimide resin thus obtained is a liquid obtained polycarbodiimide resin.
In the case of a polycarbodiimide resin obtained as it is or after distilling off the solvent, or as a powder, it may be used as it is or after being dissolved in a solvent to form a liquid.

In the present invention, for example, a plate-shaped molded product is first molded from the above polycarbodiimide resin or polycarbodiimide resin solution. The method of molding this molded article can be a method generally used in such a step and is not particularly limited, and examples thereof include injection molding, compression molding, cast molding, vacuum molding and extrusion molding. Can be mentioned.

Next, the molded product molded as described above is heated to carbonize the polycarbodiimide resin into glassy carbon, thereby obtaining the intended carbon target material for forming a thin film of the present invention. You can This carbonization step can be performed in an inert atmosphere such as vacuum or nitrogen gas, and the final firing temperature at that time is preferably 1000 ° C to 3000 ° C.

The temperature rising rate up to the final firing temperature in the carbonization step is preferably 2 ° C./hour or less, and when the final firing temperature is reached too fast, the porosity becomes 0.02% or more. Or, further, pores having a size of 0.1 μm or more are generated on the surface, which is not preferable.

The carbon target material for forming a thin film of the present invention thus obtained is extremely dense and homogeneous, and its physical properties were measured to find, for example, a porosity of 0 to 0.01.
9%, bulk density of 1.51 to 1.70 g / cm ³ , Shore hardness of 121 to 140, not only pores of 0.1 μm or more do not exist on the surface, but the surface is deformed due to swelling during use. Therefore, it was found that the carbon target material for forming a thin film is extremely excellent in that it does not cause abnormal discharge.

Incidentally, in order to form the above-mentioned protective film from the above-mentioned carbon target material for forming a thin film of the present invention, sputtering using the carbon target material for forming a thin film of the present invention as a target is carried out in the same manner as in the conventional case. You can follow.

As the above-mentioned sputtering method, there are various kinds such as direct current two-pole sputtering, direct current three-pole sputtering, high-frequency sputtering or magnetron sputtering depending on the method of gas discharge. The conditions for
Usual general conditions can be applied. For example, in the case of high frequency sputtering, the argon gas pressure is 10 ^-2 -1.
0 ^-5 Torr, the input power 0.1-100KW Tosureba well, when DC sputtering is the input power 0.
It should be 1-100 kW.

[0025]

EXAMPLES The present invention will be further described below with reference to examples.

Example 1 Mixture of 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate (80:20) [TDI] 5
4 g was reacted with 500 g of tetrachloroethylene together with 0.12 g of a carbodiimidization catalyst (1-phenyl-3-methylphosphorene oxide) at 120 ° C. for 5 hours to obtain a polycarbodiimide solution.

The reaction solution was poured into a glass petri dish, dried at 60 ° C. for 20 hours and 120 ° C. for 20 hours, and then heated to 200 ° C. at a heating rate of 1 ° C./hour to obtain a cured plate.
The obtained cured plate is heated to 2000 ° C at a heating rate of 2 ° C / hour.
The temperature was raised to 5 inch × 15 inch × 5 mmt, and an example of a carbon target material for thin film formation was obtained. The physical properties of the obtained target material were extremely good as shown in Table 1 below. In addition, "surface defect" in Table 1 represents the number of pores of 0.1 μm or more on the surface.

Next, using this target material, direct-current sputtering was performed for 10 hours at an argon gas pressure of 5 × 10 ⁻³ Torr and an input power of 500 W. The abnormal discharge at that time was 0 times, and when the target surface after sputtering was observed, it was a good glossy surface with no foreign matter attached and no protrusions formed.

Further, using the above carbon target material for forming a thin film, an argon gas pressure of 3 × 10 ⁻³ Torr and an input power of 6
Magnetron sputtering was performed for 10 hours at 00W. The abnormal discharge at that time was 0 times, and when the target surface after sputtering was observed, it was a good glossy surface with no foreign matter attached and no protrusions formed.

Further, cobalt-nickel (Co-Ni alloy) was formed as a magnetic layer by sputtering.
On the magnetic disk having a diameter of 5 inches, the carbon target material for thin film formation was used and the argon gas pressure was 3 × 10 ⁻³ To.
Magnetron sputtering was performed with rr and an input power of 600 W to form a carbon protective film having a film thickness of 250 Å. The coefficient of static friction on the surface of the obtained magnetic disk was measured and found to be as good as 0.4. Also, when this protective film forming operation was performed on 2000 magnetic disks,
The yield was 99.7%, which was also a very good result.

Example 2 50 g of methylene diphenyl diisocyanate [MDI]
Was reacted with carbodiimidization catalyst (1-phenyl-3-methylphosphorene oxide) 0.12 g in tetrahydrofuran 880 ml at 68 ° C. for 15 hours,
A polycarbodiimide solution was obtained.

The reaction solution was poured into a glass petri dish, dried at 40 ° C. for 20 hours and 120 ° C. for 40 hours, and then heated to 200 ° C. at a temperature rising rate of 1 ° C./hour to obtain a cured plate.
The obtained cured plate is heated to 1900 ° C. at a heating rate of 2 ° C./hour.
The temperature was raised to 5 inch × 15 inch × 5 mmt, and an example of a carbon target material for thin film formation was obtained. The physical properties of the obtained target material were extremely good as shown in Table 1 below.

Next, using this target material, DC sputtering was performed under the same conditions as in Example 1. The abnormal discharge at that time was 0 times, and when the target surface after sputtering was observed, it was a good glossy surface with no foreign matter attached and no protrusions formed.

Example 3 54 g of diphenyl ether diisocyanate was added to 850 ml of tetrahydrofuran to prepare a carbodiimidization catalyst (1
-Phenyl-3-methylphosphorene oxide) 0.
A reaction with 12 g was performed at 68 ° C. for 15 hours to obtain a polycarbodiimide solution.

The reaction solution was poured into a glass petri dish, dried at 40 ° C. for 20 hours and 120 ° C. for 30 hours, and then heated to 200 ° C. at a temperature rising rate of 1 ° C./hour to obtain a cured plate.
The obtained cured plate is heated to 1700 ° C. at a heating rate of 2 ° C./hour.
The temperature was raised to 5 inch × 15 inch × 5 mmt, and an example of a carbon target material for thin film formation was obtained. The physical properties of the obtained target material were extremely good as shown in Table 1 below.

Next, using this target material, DC sputtering was performed under the same conditions as in Example 1. The abnormal discharge at that time was 0 times, and when the target surface after sputtering was observed, it was a good glossy surface with no foreign matter attached and no protrusions formed.

Comparative Example 1 A graphite material (manufactured by Toyo Tanso Co., Ltd., specific gravity: 1.80) was formed in the same shape as in Example 1 to obtain a carbon target material for forming a thin film. The physical properties of the obtained target material are shown in Table 1 below. Using this target material, an argon gas pressure of 3 × 10 ⁻³ Torr,
1 magnetron sputtering with input power 600W
I went for 0 hours. The abnormal discharge at that time was 20 times,
Moreover, when the surface after sputtering was observed,
A black deposit-like swelling was observed at 0 point.

In addition, cobalt-nickel (Co-Ni alloy) was formed as a magnetic layer by sputtering.
On a magnetic disk having a diameter of 5 inches, the same graphite target material as described above was used, and the argon gas pressure was 3 × 10 ⁻³ Tor.
r, magnetron sputtering was performed with an input power of 600 W to form a carbon protective film having a film thickness of 250 Å. When the static friction coefficient on the surface of the obtained magnetic disk was measured, it was a high value of 2.0. Also, when this protective film forming operation was performed on 2000 magnetic disks,
The yield was 50%, which was a very low value.

Comparative Example 2 A novolac phenol formaldehyde resin was melt-molded into a plate and carbonized under the same conditions as in Example 1 to obtain a carbon target material for thin film formation. The physical properties of the obtained target material are shown in Table 1 below. Using this target material, magnetron sputtering was performed for 10 hours at an argon gas pressure of 3 × 10 ⁻³ Torr and an input power of 600 W. The abnormal discharge at that time was 10 times, and when the surface after sputtering was observed, black deposit-like swelling was observed at 18 places.

Comparative Example 3 The cured plate obtained in Example 1 was heated to 20 ° C. at a heating rate of 5 ° C./hour.
The temperature was raised to 00 ° C., and a target material having the same shape as in Example 1 was obtained. Table 1 shows the physical properties of the target material. DC sputtering was performed using this target material under the same conditions as in Example 1. The abnormal discharge at that time was 10 times, and when the surface after sputtering was observed, it was observed that there were black deposit-like swells at 10 places.

[0041]

[Table 1]

Claims (7)

[Claims] 1. A carbon target material for forming a thin film, which comprises glassy carbon produced from a polycarbodiimide resin as a raw material. 2. A bulk density of 1.51 g / cm ^{3 to} 1.7.
The carbon target material for forming a thin film according to claim 1, having a porosity of 0 g / cm ³ and 0 to 0.019%. 3. The carbon target material for forming a thin film according to claim 1, wherein pores of 0.1 μm or more do not exist on the surface. 4. A method for producing a carbon target material for forming a thin film, which comprises molding a polycarbodiimide resin or a composition mainly composed of a polycarbodiimide resin into an appropriate shape, and then carbonizing the molded product. 5. The method for producing a carbon target material for forming a thin film according to claim 4, wherein carbonization of the molded product is performed in a vacuum or in an inert atmosphere. 6. The carbonization of the molded product is from 1000 ° C. to 300 ° C.
The method for producing a carbon target material for forming a thin film according to claim 5, which is performed in a temperature range of 0 ° C. 7. The method for producing a carbon target material for forming a thin film according to claim 6, wherein carbonization of the molded product is performed at a temperature rising rate of 2 ° C./hour or less.