JP2003017435A - Member for vitreous carbon coated ion implantation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member for a vitreous carbon coated ion implantation apparatus where foreign matters do not stick on a silicon wafer, since pure ion beam can be implanted to a silicon wafer without inclusion of foreign matters in ion beam, and which is superior in durability, since a glass-like carbon film applied to a substrate will not peel readily. SOLUTION: In the member for a vitreous carbon coated ion implantation apparatus, at least a substrate surface irradiated with an ion beam is coated with a vitreous carbon film. In the surface of the vitreous carbon film, regular reflectance of light injected at an angle of 30 degrees with respect to the surface of the vitreous carbon film is 10% or more, average roughness Ra by JIS B 0601 is 0.03 to 3 μm, and maximum roughness Rmax is 0.3 to 30 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass-like carbon-coated ion implantation device member used in a slit member or the like for an ion guide in an ion implantation device.

[0002]

2. Description of the Related Art A technique of implanting impurities into a semiconductor in an ionic state is a technique industrialized in the 1970s and is now widely used in many silicon semiconductor products including LSI. Ion implantation in a semiconductor device is performed by ionizing a target impurity element in a silicon wafer and accelerating it to an energy of several tens to several hundreds eV.

At this time, if a component other than the target element is present, impurities other than the target are implanted into the silicon wafer, and there is a risk that the initial performance may not be obtained. Therefore, high-purity materials that do not adversely affect the semiconductor are required for the components of the ion implantation apparatus.

FIG. 2 is an explanatory view showing an example of a conventional ion implantation apparatus. As shown in FIG. 2, in the conventional ion implanter 20, a gas containing an impurity element of interest is put into a high-density plasma state, an ion generator 21 that generates ions by plasma, and the generated ions are generated. An extraction unit 22 that gives energy required to extract from the ion generator 21, an ion analysis unit 23 that selects the extracted ions into target ions, and an acceleration unit 24 that accelerates the ions to generate an ion beam are provided. ing.

Further, the ion implanter 20 includes a focusing section 25 for focusing the ion beam, and a scanning section 2 for scanning the ion beam to uniformly hit the surface of the silicon wafer.
6, and an ion implantation chamber 27 for implanting ions into the silicon wafer 19 is provided, and each member constituting the ion implantation apparatus 20 is connected by a slit member 28 capable of moving an ion beam therein. Has been done.

That is, the ions generated in the ion generator 21 pass through the extraction unit 22, the ion analysis unit 23, and the acceleration unit 24 to become an ion beam. The ion beam is slit by the focusing unit 25 and the scanning unit 26 in this order. Member 2
The silicon wafer 19 travels in the ion implantation chamber 8 and is implanted into the silicon wafer 19 installed in the ion implantation chamber 27.

The material of the portion which makes contact with the ion beam in each member constituting the ion implantation apparatus 20 is
Materials and structural considerations have been made to maintain high purity and prevent foreign matter from entering, and above all, the ion generator, which is the ion source, and the slit member 28 in the scanning unit are high in purity. Since the ions of energy collide with each other, impurities and foreign substances from the constituent materials are likely to be mixed in, and consideration must be given to the other materials.

Conventionally, as such a high-purity material, a graphite material has been used, which is a material that is unlikely to adversely affect a silicon wafer and which can easily secure a high-purity material.

[0009]

However, since the graphite material is an aggregate of fine particles such as coke, fine foreign matter (graphite particles) is mixed in when the ion beam collides. Therefore, foreign matter adheres to the silicon wafer, resulting in a poor product yield.

Further, in order to solve the above problems, the inventors of the present invention, as disclosed in JP-A-8-171883, have a high purity pyrolytic carbon coating of 20 to 50 μm on the surface of a graphite base material. It was proposed to make carbon parts by coating the. However, the high-purity pyrolytic carbon film thus formed may be etched and consumed by the ion beam in the ion implantation device, exposing the graphite base material, and preventing the graphite base material from being exposed. Therefore, if the high-purity pyrolytic carbon film is thickened, the coating film may peel due to a mismatch in the coefficient of thermal expansion with the base material, and there is still room for improvement.

Further, Japanese Patent Laid-Open No. 5-246703 proposes to use glassy carbon as a slit member. However, this slit member is desired because it is necessary to process hard glassy carbon itself. It was difficult to obtain the slit member having the shape of, and the manufacturing process thereof was complicated.

Further, the slit member made of the above glassy carbon is more
When exposed to an ion beam, the amount of fine foreign matter (graphite particles) scattered from the surface was remarkably small, but when the foreign matter was mixed into the ion beam and the foreign matter adhered to the silicon wafer, Since the defect rate of semiconductor chips manufactured using this silicon wafer is greatly increased, it has been desired to reduce the amount of foreign matter mixed in the ion beam.

In view of the above conventional problems, the present invention can implant a pure ion beam into a silicon wafer without mixing foreign matter into the ion beam.
Foreign matter does not adhere to the silicon wafer, and
An object of the present invention is to provide a member for a glassy carbon-coated ion implantation device which is excellent in durability because the glassy carbon film coated on the substrate does not easily peel off.

[0014]

In order to achieve the above-mentioned object, the present inventors have made a glassy carbon-coated ion implantation device member in which at least the surface of a substrate irradiated with an ion beam is coated with a glassy carbon film. The results of various studies on the relationship between the surface state of the glassy carbon film and the mechanism of generation of fine foreign matter showed that there was a close relationship between the surface smoothness and surface roughness of the glassy carbon film and the amount of foreign matter generation. I found that there is.

That is, usually, the glassy carbon film has an amorphous homogeneous continuous dense structure, and when such a glassy carbon film is exposed to an ion beam, its surface is uniformly consumed. However, fine foreign matter (graphite particles) does not come off. However, when the surface smoothness and surface roughness of the glassy carbon film deviate from a certain range, the amount of foreign matter scattered from the surface of the glassy carbon film increases, or the glassy carbon film peels off. The inventors have newly discovered this and completed the present invention. Here, the smoothness of the surface of the glassy carbon film is evaluated by the regular reflectance of light incident at an angle of 30 degrees with respect to the surface of the glassy carbon film, and the surface of the surface of the glassy carbon film is evaluated. The roughness is evaluated by the average roughness Ra and the maximum roughness Rmax according to JIS B0601.

The present invention relates to a member for a glassy carbon-coated ion implantation device in which at least the surface of a substrate irradiated with an ion beam is coated with a glassy carbon film, and the surface of the glassy carbon film is the glass-like carbon film. 3 for the surface of the carbon film
The regular reflectance of light incident at an angle of 0 degree is 10% or more, and the average roughness Ra according to JIS B 0601 is 0.0.
3 to 3 μm, and the maximum roughness Rmax is 0.3 to
It is a member for a glassy carbon film ion implantation device, which has a thickness of 30 μm. Hereinafter, the present invention will be specifically described with reference to embodiments.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a glassy carbon-coated ion implantation device member in which at least the surface of a substrate irradiated with an ion beam is coated with a glassy carbon film,
The surface of the glassy carbon film has a regular reflectance of 10% with respect to the light incident on the surface of the glassy carbon film at an angle of 30 degrees.
The above is the average roughness Ra according to JIS B 0601.
Is 0.03 to 3 μm, and the maximum roughness Rmax is 0.3 to 30 μm.

FIG. 1 is a partial cross-sectional view schematically showing an example of the glassy carbon-coated ion implantation device member of the present invention (hereinafter, also referred to as glassy carbon-coated member). As shown in FIG. 1, the glassy carbon coating member 10 of the present invention comprises a substrate 12 having a through hole in the vicinity of its center, and a glassy carbon film 11 coated on the inner wall surface of the through hole of the substrate 12. Has been done.

In the glassy carbon coating member 10 of the present invention, the inner wall surface of the through hole of the substrate 12 has a glassy carbon film 11 formed thereon.
And the ion beam travels on the surface (ion passage wall 13) of the glassy carbon film 11. That is, even if impurities or foreign matter scattered from the inner wall surface of the base 12 are present, since the inner wall surface of the base 12 is completely covered with the glassy carbon film 11, the impurities or foreign matter are not covered by the ion passage wall. 13 does not scatter and does not mix with the ion beam. The outer peripheral portion of the substrate 12 may also be covered with the glassy carbon film. Base 1
Impurities and foreign substances scattered from the outer peripheral portion of 2 may be indirectly mixed in the ion beam. Further, depending on the method of forming the glassy carbon film by coating, only the inner wall surface of the through hole of the base 12 is glassy. This is because it may be difficult to cover with a carbon film.

In the glassy carbon coating member 10 of the present invention, the regular reflectance of the light incident on the ion passage wall 13 at an angle of 30 degrees is 10% or more, and JIS B 060 is used.
The average roughness Ra according to No. 1 is 0.03 to 3 μm, and the maximum roughness Rmax is 0.3 to 30 μm. Since such an ion passage wall 13 has almost no unevenness on its surface, even if a mechanical shock such as contact or collision of a high-energy ion beam is applied to the ion passage wall 13, the ion passage wall 13 is not affected. There is no chipping on the wall 13 and no foreign matter (fine particles generated by chipping) is mixed in the ion beam. In addition, the glassy carbon film 11
The glassy carbon film 11 does not peel off from the substrate 12 because it has excellent adhesive strength to the substrate 12.

When the regular reflectance of the ion passage wall 13 is less than 10%, even if the average roughness Ra and the maximum roughness Rmax of the ion passage wall 13 are within the above-mentioned ranges, the ion passage wall 13 has a minute amount. When a large number of irregularities are present and a mechanical impact such as contact or collision of a high-energy ion beam is applied, the convex portions of the minute irregularities may be chipped. Adheres to the surface of and becomes foreign matter.

In addition, the JIS B 0 of the ion passage wall 13
If the average roughness Ra according to 601 is less than 0.03 μm, it takes a considerable amount of time for polishing work to make the ion passage wall 13 smooth in this way, resulting in a decrease in productivity and an increase in cost. Invite. On the other hand, the ion passage wall 13
When the average roughness Ra of the ion-exchange wall exceeds 3 μm, the ion passage wall 13
Even if the regular reflectance and the maximum roughness Rmax of the above are within the ranges described above, there is a portion where relatively large irregularities are present in the ion passage wall 13, and the high-energy ion beam has the above irregularities. When a mechanical impact such as contact or collision with the convex portion is applied, a chip is generated, and the chipped convex portion adheres to the silicon wafer to become a foreign substance.

Furthermore, JIS B of the ion passage wall 13
If the maximum roughness Rmax according to 0601 is less than 0.3 μm, a considerable amount of time is required for polishing the ion passage wall 13, resulting in a decrease in productivity and an increase in cost. on the other hand,
If the maximum roughness Rmax of the ion passage 13 exceeds 30 μm, even if the regular reflectance and the average roughness Ra of the ion passage wall 13 are within the ranges described above, there are large irregularities on the ion passage wall 13. When a high-energy ion beam is subjected to a mechanical impact such as contact or collision with the above-mentioned large uneven projections, chipping occurs, and the chipped projections adhere to the silicon wafer and become foreign matter. .

That is, the glassy carbon coating member 10 of the present invention
, The specular reflectance and average roughness Ra of the ion passage wall 13
Both the maximum roughness Rmax and the maximum roughness Rmax need to be within the above range, and if any one of them is out of the above range, the effect of the present invention cannot be obtained.

As the raw material of the glassy carbon film 11, for example, organic polymers such as vinyl chloride resin, polyvinyl alcohol, oil-soluble phenol resin, alkylphenol resin, chlorinated paraffin, chlorinated polypropylene, vinyl acetate resin and polycarbonate resin are used. Among these, vinyl chloride resin is preferable in view of inclusion of impurities and the like.

The regular reflectance of the ion passage wall 13 is larger than the regular reflectance of the inner wall surface of the base 12 before being covered with the glassy carbon film 11, and the regular reflectance of the ion passage wall 13 is further increased. Has a tendency to increase in proportion to the thickness of the glassy carbon film 11, so it is desirable to appropriately determine the thickness of the glassy carbon film 11 in consideration of these points. Specifically, the thickness of the glassy carbon film 11 is preferably about 0.5 to 10 μm. When the thickness of the glassy carbon film 11 is less than 0.5 μm, the substrate 1
Since the surface shape of 2 has a great influence on the surface of the glassy carbon film 11, the specular reflectance, the average roughness and the maximum roughness of the glassy carbon film 11 may be out of the ranges described above.
In addition, the thin glassy carbon film 11 is formed on the substrate 12 as described above.
It is difficult to form it uniformly on the entire inner wall surface.
On the other hand, if the thickness of the glassy carbon film 11 exceeds 10 μm, minute cracks are likely to occur in the glassy carbon film 11, and impurities or foreign matter may be scattered and mixed into the ion beam.

Further, it is desirable that an impregnated layer of glassy carbon is formed at the interface of the substrate 12 with the glassy carbon film 11. This is because the adhesive strength between the glassy carbon film 11 and the substrate 12 becomes extremely high. The thickness of the glassy carbon impregnated layer in the substrate 12 is preferably about 500 to 6000 μm from the interface between the substrate 12 and the glassy carbon film 11. When the thickness of the impregnated layer is less than 500 μm, the adhesive strength between the substrate 12 and the glassy carbon film 11 is not so high, while when the thickness of the impregnated layer exceeds 6000 μm, the predetermined thickness is obtained. It takes time to form the glassy carbon film 11 and it is difficult to control the thickness of the glassy carbon film 11.

As shown in FIG. 1, the base body 12 is a quadrangular prism having a through hole formed near the center thereof, but the shape of the base body 12 is not limited to this. It may have any shape such as a cylindrical shape having a hole, an elliptic cylindrical shape, and a polygonal cylindrical shape. Further, the cross-sectional shape of the through hole is not particularly limited to the rectangular shape as shown in the drawing, for example,
It may have any shape such as a circle, an ellipse, and a polygon.

The material forming the substrate 12 is not particularly limited, and examples thereof include graphite and C / C composite.

The inner wall surface of the substrate 12 before being covered with the glassy carbon film 13 preferably has a regular reflectance of 5% or more with respect to light incident on the inner wall surface at an angle of 30 degrees. . When the regular reflectance of the inner wall surface of the substrate 12 is less than 5%, the inner wall surface is in a rough state and covered with particles that are easily desorbed. Therefore, even if the inner wall surface is covered with the glassy carbon film 11, Particles may be detached together with the glassy carbon film 11 and mixed into the ion beam, and foreign matter may adhere to the silicon wafer.

As described above, in the glassy carbon coating member of the present invention, at least the surface of the substrate to which the ion beam is applied is coated with the glassy carbon film, and the surface (ion passage wall) of the glassy carbon film is covered. The regular reflectance of light incident at an angle of 30 degrees is 10% or more, and JIS B 0
The average roughness Ra according to 601 is 0.03 to 3 μm,
Moreover, the maximum roughness Rmax is 0.3 to 30 μm. That is, in the glass-like carbon coating member of the present invention, the surface of the ion passage wall on which the ion beam travels is very smooth, and since there is almost no large unevenness, the ion beam contacts or collides with the ion passage wall. , Even if a mechanical shock is applied, the ion passage wall is chipped (foreign matter)
Does not occur. Therefore, according to the glassy carbon coating member of the present invention, a foreign substance is hardly mixed in the ion beam, a pure ion beam can be injected into the silicon wafer, and the foreign substance can adhere to the silicon wafer. Absent. Further, since the glass-like carbon film and the substrate have excellent adhesive strength, the glass-like carbon film does not easily peel off from the substrate, and the glass-like carbon-coated member has excellent durability.

Next, the method for producing the glassy carbon coated member of the present invention will be described. The glassy carbon coated member of the present invention can be manufactured by forming a glassy carbon film on the surface of a substrate.

First, the substrate is manufactured. As described above, various materials can be used as the material forming the above-mentioned substrate, but in the following, the most commonly used graphite in the ion implantation apparatus will be described as an example. .

Various methods can be mentioned as a method for producing a substrate made of graphite, for example, CI.
By cutting out the isotropic graphite block obtained by the P method, the HIP method, or the like, a substrate having a through hole near its central portion, such as the substrate 12 shown in FIG. 1, can be manufactured.
As a method for cutting out the above isotropic graphite block, dry cutting or grinding is desirable in order to prevent contamination with a cutting fluid. Further, the isotropic graphite block may be cut out by ultrasonic waves or electron beams. It is desirable to subject the thus manufactured substrate to a purification treatment with a halogen gas or the like.

The inner wall surface of the through hole formed in the vicinity of the central portion of the base body is subjected to a polishing treatment so that the regular reflectance of light incident at an angle of 30 degrees with respect to the inner wall surface becomes 5% or more. Is desirable. Further, it is more preferable that the regular reflectance of the light is 5 to 15%. As the polishing treatment, for example, a normal polishing method such as a buff, a pad, a brush, and a sandpaper is sufficient, but especially when a buff or a pad is used, the particles separated by the polishing are clogged in the pores of the substrate. Therefore, there is an advantage that the gas impermeable effect after coating the glassy carbon film is increased.

Next, a glassy carbon film is formed on the inner wall surface of the through hole of the substrate so that the light incident on the surface (ion passage wall) of the glassy carbon film at an angle of 30 degrees is positive. A glassy carbon-coated member having a reflectance of 10% or more, an average roughness Ra according to JIS B 0601 of 0.03 to 3 μm, and a maximum roughness Rmax of 0.3 to 30 μm is manufactured.

As a method for coating the surface of the substrate (inner wall surface of the through hole) with the glassy carbon film, for example, an organic polymer solution obtained by dissolving the above-mentioned pyrolyzed product of the organic polymer in a solvent is used as the substrate. The method of applying to the inner wall surface of, and baking at 1000-1200 degreeC in inert or vacuum can be mentioned.

Examples of the method of applying the organic polymer solution to the inner wall surface of the through hole of the substrate include a method of applying with a brush or a method of applying by dipping. The organic polymer solution may be applied not only to the inner wall surface of the through hole of the base but also to the outer peripheral portion of the base. Then, if necessary, the surface of the glassy carbon film is subjected to polishing treatment such as etching to adjust the regular reflectance, average roughness Ra, maximum roughness Rmax, etc. of the surface of the glassy carbon film (ion passage wall). You may.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 3 are substantially the same in shape as the substrate 12 shown in FIG. 1 and have a bulk specific gravity of 1.85.
The surface of the isotropic graphite (specular reflectance 0.2%) was polished with an industrial pad (Scotchbright 7448), and the specular reflectance was 10 to 15%.

Next, polyvinyl chloride was thermally decomposed in nitrogen at 390 ° C. to obtain a tar-like carbon precursor. This carbon precursor was dissolved in trichlene and applied on the surface of the above-mentioned isotropic graphite with a brush, and then baked at 1200 ° C. in a vacuum atmosphere to form a glassy carbon film. The reflectance is 15 to 20%, the average roughness Ra is 0.04 to
A glassy carbon-coated member having a thickness of 1.0 μm and a maximum roughness Rmax of 0.5 to 10 μm (see Table 1 below) was manufactured.

The specular reflectance was measured by using a gloss meter (manufactured by Minolta Camera Co., Ltd.) to specular reflectance (%) of incident light at 30 degrees, and the surface roughness was measured by an electronic surface roughness meter ( Made by Mitoyo
JIS B 0 with surf test type 201)
According to 601, average roughness Ra (μm) and maximum roughness Rm
The ax (μm) was measured.

Examples 4 and 5 The substrate 12 has substantially the same shape as that of the substrate 12 shown in FIG. 1 and a bulk specific gravity of 1.60.
The surface (regular reflectance of 0.1%) of the extruded graphite was polished with an industrial pad (Scotchprite 7448) to have a regular reflectance of 5%. Then, the extruded graphite surface was coated with a glassy carbon film in the same manner as in Example 1,
Specular reflectance of ion passage wall is 10 to 12%, average roughness Ra
Is 2.0 to 3.0 μm, and the maximum roughness Rmax is 20 to 25
A glassy carbon-coated member having a thickness of μm (see Table 1 below) was manufactured.

Comparative Example 1 A glassy carbon-coated member was produced in the same manner as in Example 1 except that the glassy carbon film was not formed on the inner wall surface of the isotropic graphite substrate.

Comparative Example 2 A glassy carbon-coated member was produced in the same manner as in Example 4 except that the glassy carbon film was not formed on the inner wall surface of the extruded graphite substrate.

Comparative Example 3 The regular reflectance of the ion passage wall was 6%, and the average roughness Ra was 4.2.
A glassy carbon-coated member was produced in the same manner as in Example 4 except that the maximum roughness Rmax was 40 μm.

The amount of foreign matter generated from the ion passage walls of the glassy carbon coating members produced in Examples 1 to 5 and Comparative Examples 1 to 3 was measured by the following method, and the coating state of the glassy carbon film was observed. did. The results are shown in Table 1.

(1) Measurement of the amount of foreign matter A sample (7 × 7 × 7) was placed in a glass cell (15φ × 301).
3 pieces) were put in, vibration was given at an amplitude of 0.05 mm and a frequency of 60 Hz, and the number of foreign matters (fine particles) of 0.3 μm or more was measured by a particle counter.

(2) State of glassy carbon film The state of the glassy carbon film of the manufactured glassy carbon coating member was visually observed to confirm the occurrence of peeling.

[0049]

[Table 1]

As is clear from the results shown in Table 1, the regular reflectance of the ion passage wall is 10% or more, and the average roughness is 0.0.
The amount of foreign matter measured by the glassy carbon coating members according to Examples 1 to 5 having a maximum roughness of 3 to 3 μm and a range of 0.3 to 30 μm is extremely small, and the glassy carbon film is peeled off. Did not occur. On the other hand, in the members according to Comparative Examples 1 and 2, since the substrate was not covered with the glassy carbon film, a large amount of foreign matter scattered from the substrate was measured. Further, in the glassy carbon coating member according to Comparative Example 3, the regular reflectance of the ion passage wall was low, and both the average roughness and the maximum roughness of the ion passage wall were large, and therefore the glassy carbon film peeled off. I did not, but there was a lot of foreign matter.

[0051]

As described above, according to the glassy carbon coating member of the present invention, even if the ion beam comes into contact with or collides with the surface of the glassy carbon film coated on the surface of the substrate irradiated with the ion beam. Since almost no scattered foreign matter is present, impurities or foreign matter are not mixed into the ion beam, a pure ion beam can be injected into the silicon wafer, and the foreign matter does not adhere to the silicon wafer. Further, since the glassy carbon film has excellent adhesive strength to the substrate, the glassy carbon film does not easily peel off, and the glassy carbon coating member has excellent durability.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing an example of a glassy carbon coating member of the present invention.

FIG. 2 is an explanatory view schematically showing an example of a conventional ion implantation device.

[Explanation of symbols]

10 Glassy carbon coated member 11 Glassy carbon film 12 Base 13 ion passage wall 19 Silicon wafer 20 Ion implanter 21 Ion generator 22 Drawer 23 Ion analysis unit 24 Accelerator 25 Converging section 26 Scanning section 27 Ion implantation room 28 Slit member

Claims (2)

[Claims] 1. A member for a glassy carbon-coated ion implantation device in which at least the surface of a substrate irradiated with an ion beam is coated with a glassy carbon film, wherein the surface of the glassy carbon film is the glassy carbon film. The regular reflectance of light incident at an angle of 30 degrees to the surface of J is 10% or more.
The average roughness Ra according to S B 0601 is 0.03 to 3 μ.
m and the maximum roughness Rmax is 0.3 to 30 μm
The glass-like carbon film ion implantation device member characterized by the following. 2. The glassy carbon according to claim 1, wherein the surface of the substrate before being coated with the glassy carbon film has a regular reflectance of 5% or more for light incident at an angle of 30 degrees to the surface. A member for a coated ion implanter.