JPH05508509A - Improved sputtering target for coating compact discs, method of using the same, and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Compact disk coaching sputtering target and its 　　°'6　゛And hole standing technique Saraoka! The present invention provides a method for applying a metal coating to an annular region of a substrate such as a compact disc. Sputtering target suitable for use in cathodic sputtering equipment that performs sputtering Regarding the cut. This type of target is used in sputtering coating processes. Methods of using the kit are also within the scope of this invention.

Kimi Gogo 1 Sputtering equipment has traditionally been used to deposit thin films of certain materials onto substrates. used. This type of device is applied as a thin film or coating on a substrate. Ion bombing with a gas to a target cathode with a surface made of the material to be folded Birdment included.

The target forms part of a cathode assembly, and the cathode assembly is connected to an anode. both placed in an evacuable chamber containing an inert gas, e.g. argon. . A high voltage is applied to the cathode and anode to ionize the gas particles. positive charge The gas ions are attracted to the cathode and hit the target surface with an impact. The result is release of target material. The cathode target material released in this way is The film passes through a vapor chamber (generally called a vacuum chamber) and is folded onto the desired substrate as a thin film. The substrate is generally provided near the anode.

In addition to using an electric field, an arcuate magnetic field can also be used to increase the sputtering rate. the arcuate magnetic field overlaps the electric field; Moreover, it forms a closed loop on the surface of the sputtering target.

These methods are known as magnetron sputtering methods. arched magnetic field traps electrons in an annular region adjacent to the target surface, resulting in target to increase the number of collisions between electrons and gas atoms and release the target material. This results in an increase in the number of positively charged gas ions in the area that strikes the cut. Therefore, the applicable The target material has large areas on the target surface known as target raceways. Erosion within the annular portion of the body (i.e., consumed to fold onto the substrate) I come to do it.

As is often done, cathodic sputtering is used to produce extremely thin conductive films. used for thin film coating of semiconductor elements such as silicon wafers, consisting of . In these cases, as in other cases, the goal is to obtain a uniform thin film coating. forming a semiconductor element on a semiconductor element. July 78, 1987, A5 (4), Jour, Vacuum 5science & Techno1g y (Science and Technology of Vacuum, Magazine), title of presentation'' (: rystallogr aphLc Target Effects in MagnstronSpu tlering Systems” (for magnetron sputtering equipment) Dr. Wickertsham in ``Effects of Targets with Crystalline Structures'') In an early study conducted with Wehner et al. (1) (note (1), G. , Wehner, J. ^9p1. Phys, 26.1056 (1955) and G, ni, l! Iehner, Phys, Rev, 102.690 (195B) ) is reported as follows. In other words, it has a dense polycrystalline structure. Coating by sputtering applied using sputtering target The uniformity of the target is achieved by controlling the direction of the crystal structure of the target. This means that it can be increased. This desire for uniformity led to Such deposits have maximum thickness in the core and taper off radially outwards The orientation of the crystal structure is controlled so that it has uniform folds and does not become a substrate with objects. It was decided that the company would produce targets that were controlled by the company.

Currently, the production of compact discs (CDs) is becoming increasingly important. It is becoming a sputter coating field, and in this sputter coating field, is applied to store desired audio information on a thin aluminum film on a disk-shaped substrate. ing. However, it is difficult to achieve uniform coating over the entire disk substrate. In contrast, this operation requires an aluminum ring, which can be seen in Figure 1. It is used on a substrate 6 such as Mylar plastic (trade name), as shown in FIG. a ring as shown by the annular region 2 of a standard compact disc 4 . For this purpose, a sputtering apparatus such as the one schematically shown in Figure 2 is used. In this apparatus, the substrate 6 to be sputtered is has one control aperture 8, which includes a removable cover plate 12 and a mask portion 14. ．． It is fixedly mounted in the sputtering apparatus vacuum chamber by a mandrel having a diameter of 16. Ta The target 18 thus covers the cover plate 12 of the assembly which shields the substrate 6. The target 18 is uniformly scanned over the entire substrate 6 using the mask portions 14 and 16. As a result, a sputter coat is applied to the desired annular portion 2 on the substrate. As a result, a CD4 as shown in FIG. 1 is generated.

In such conventional CD sputtering equipment, the target is The uniform radiation of the coating material onto the disk mask surface actually reduces sputtering. This results in wasted materials because these coating materials , because it comes into contact with parts on the CD such as the mask 14, 16 and the cover plate 12. Ru. This fact is important for uniform coating on substrates such as silicon sea urchins. It will be contradictory to what you are doing.

Therefore, the number of CDs coated per sputtering target To increase the coating, apply the desired type of coating to the circular substrate area where coating is desired. Such a preferred target material is capable of emitting a It is desirable to provide a fee. In addition, such controlled targets By emitting light, collection efficiency is increased.

Mikai 3J01 Hotaru Tomo According to the present invention, it has been surprisingly discovered that the metal grid of the target metal The defined crystallographic orientation in the dense direction is The annular area of the CD substrate is provided with a non-uniform radiation which actually coats the annular area well. This means that it is effective in terms of Simply put, the direction of closest density of the target As explained below, there are ways to do this. is substantially perpendicular to the plane of the substrate surface to be coated (i.e. 9 They are aligned on the - line with an angle of 0°±151 degrees.

The present invention will be further explained using the accompanying drawings.

m-1 Figure 1 is a schematic diagram of a standard compact disc; Figure 2 is a commercially used CD. A diagram schematically showing the arrangement of a target and a substrate of a sputtering device; Figure 3 is a schematic diagram showing a face-centered cubic atomic lattice arrangement; Figure 4 is an indeterminate diagram with b/a of 1. Schematic diagram showing a normal radiation coating for a target 18 consisting of shaped sintered powder: Figure 5 shows approx. Schematic diagram showing normal radiation coverage of target 18 with b/a of 3; FIG. 6 shows the target of the present invention, which is installed in a conventional commercial CD sputtering apparatus. Schematic diagram showing the installed condition - Figure 7 shows the preferred crystallographic structure for use in the present invention. A schematic diagram showing the method for obtaining oriented metals; Figure 8 shows various test targets. A Monte Carlo method that shows the coating thickness per location on the substrate for This is a graph of data obtained from a computer simulation by; FIG. 9 shows a Monte Carlo computer system of the type described in connection with FIG. FIG. 3 is a graph of data obtained from simulation.

Among many metals, for example, AI, Au, Pt, Cu.

Ni, Ag, Pd, and alloys of these metals have a face-centered cubic lattice (F It is known in the art to have a lattice arrangement of atoms known as 'CC). . If we pay attention to Figure 3, such an FCC atomic lattice is shown, where the A1 original Children 20 are placed at all cube intersections, and one atom (20a) is placed at the center of each face. It is.

The close-packed configuration is defined as the direction of the lattice, in which the atoms It is arranged in its most densely enclosed state. These atoms are pure elements or, as in many cases, alloys containing FCC metals. It can be arranged as follows. Therefore, FCC metal herein refers to pure Such face-centered orientation of atoms or ions in an element or in an alloy Refers to pure elemental metals and alloys exhibiting a square lattice (FCC).

As one aid in arranging atoms in a lattice arrangement, the closest-packed direction is For purposes of defining the three-dimensional coordinates x, y.

2 is used as shown in FIG. For an FCC type lattice, the closest packed direction is two-sided. be defined as a vector corresponding to the reciprocal of lx, ly and O units in the direction Can be done. Therefore, for an FCC lattice, the closest packed direction is indicated at 110.

In contrast to the FCC lattice structure, Fe, Ta, Ba, Ce.

Materials such as Mo, W and V exhibit a body-centered cubic lattice (BCC), in which vertical In addition to the arrangement of atoms or metal ions at the intersections of the square planes, the center of the cube One atom or ion is located in the center of each face of the cube. does not exist, so in the CC lattice, the closest packed direction is represented by 111. Ru. In sputtering coating methods, the release of sputtered atoms is The output is preferentially along the closest direction of the target (i.e. on a line in the closest direction). ) occurs in the direction.

In Figure 4, the oriented radiation vector E is shown for amorphous sintered powder material. be. Here, vector E is parallel to the normal on the surface of target 18; Or, to put it another way, perpendicular to the plane of the target surface. radiation envelope The surrounding area 24 has a large radius and a small radius a, which have the same dimensions. child As in, for the device in this case the enclosing area is a circle. What should be noted here is that The ratio b/a is a function of the particular target used. sintered powder In , the ratio b/a is known as 1. On the other hand, cast metal or In processed metals, the ratio b/a is greater than 1, typically 3, giving an elliptical radial envelope. Provide an enclosed area. (See Figure 5.) Returning to Figure 4 again, the target during sputtering at an angle of 0 degrees as shown in the figure. The probability of an atom being ejected from the cut is equal to a fixed number times the cosine θ , that is, p(θ)=Kcos(θ).

This equation is known as the normal cosine radiation equation, and is used for sputtering coatings. It is well known to engineers in the same industry.

FIG. 5 shows the theoretical radiation envelope for a cast or fabricated metal. This diagram Then, the ratio b/a is thicker than 1 (, generally 3, and the surrounding area 24 is therefore It forms an oval shape. This is the type of b/a radiation envelope, and this type of envelope In the fact that the present invention involves regions, preferred coatings for CD substrates This means that cast or processed metals, especially aluminum, are preferred as the material for The line 26 of the target 18 in FIG. direction. That is, the 110 direction is indicated by line 26. known theory Accordingly, the preferred radiation from target 18 in FIG. It should occur along the vector E which takes λ. From vector E to angle 0 degrees The probability of radiation at is determined by the following cosine radiation equation with known direction: p(θ)=Kcos(θ)/[(b/a)"sin"(θ)+cos ”　(θ)] What the inventors of the present invention surprisingly discovered is that the present sputtering system By changing the angle λ of the This means that get release is found.

As previously mentioned, a conventional CD sputtering system is shown in Figure 2. be. Details of cathode sputtering equipment are generally well known and can be found here. One such device, which need not be repeated, is US Pat.

4.478,701 (owned by Welch), and the disclosures of this patent are incorporated herein by reference to the extent necessary to provide a sufficient disclosure of this specification. It is used for

Equipment currently in commercial use for cathode sputtering of CDs! is everything A target 18 is used, and the target is arranged parallel to the CD substrate 6. Ru. It should be noted that the CD board 6 is not mounted on a jukebox type feeder. This means that the jukebox-type feeding device continuously The CD is rapidly fed, sputtered, and removed from the vacuum chamber. . The CD includes a cover plate 12 connected to the mandrel and an annular portion 2 on the sputter coating. The delivery mandrel 10 with a suitable mask member 14.16 suitable for exposing the It has a central aperture 8 inserted above. During sputtering practice, the CD is held stationary relative to the target 18.

What we have discovered is that CD sputtering can be The closest-packed direction is such that the angle λ in Figure 5 is zero or almost zero (0 ± 15°). If it is set, it will be considerably stronger (I think it will be strengthened. More importantly) means that the preferred radiation vector E toward the target is such that E is provided in a vacuum chamber. This is almost perpendicular to the surface of the CD substrate. inserted into the device of FIG. A schematic diagram of a target 18 according to the invention is shown in FIG. After insertion, the target 18 (of FIG. 6), whose arrangement in the close-packed direction 26 is such that the angle λ is zero or substantially zero. (±15″″).

Therefore, the close-packed orientation of the target determines the uniformity of deposition over the entire CD. Set. This directionality is achieved by moving the target material from the melt into the melt using a directional solidification method. or more preferably after casting. It is possible to control this by processing the metal. Regarding the latter method by rolling aluminum and then annealing the rolled aluminum. yields the 110 direction, i.e., the direction at 45° to the normal to the surface, which is , CD sputtering using conventional equipment in which the target CD substrate and the other are parallel to each other. Cannot be used for rings.

When aluminum is unidirectionally cast, 110 directions are obtained, but these 110 directions are parallel to the normal on the surface and thus a CD sputtering apparatus of the type shown in FIG. I prefer to use the vine. In aluminum extrusion processing, the angle of 35° with the perpendicular on the surface is This results in 110 directions.

The aluminum processing method uses approximately 400 to 600 tons of unidirectional compressive force. While reducing the billet, the reduced billet is heated to a temperature in the range of about 500 to 800@F. Heat treatment is performed at ambient temperature. In a preferred method, the billet is weighed about 500 tons. The billet is reduced by force while being heated to a temperature range of about 650 to 700″F. Apply pressure until the length of is about half of the initial length of the head. Then the vaginal billet is cooled It is then machined and finished into the specified shape required by the end user. below Preferred operating steps are performed: 1. Use commercial aluminum material with a diameter of 5.5" and alloy number 1100.

2. Cut billet from material 3.25" (±0.125") long.

3. Insert the billet into a flat mold set on a 2000 ton press.

4. Press the billet vertically while heating it.

5. Press in a mold set to a length of 1.625".

6. Perform water quenching.

7. Machining each tip into the desired external shape of the target.

As mentioned above, controlled solidification of metals is employed to achieve the desired (110>direction). get. For one such technique, which is clearly not preferred, Fig. 7 This is explained in relation to. In this figure, molten metal 30 is poured into a mold 32.

First, the mold 32 acts as a hot water reservoir, and the metal 34 in which fine crystal grains grow. A thin layer of molten metal is formed surrounding the area of contact between the molten metal and the mold surface. this thin layer has a thickness within the range of approximately 0.030 to 0.040". The part located in the center is the molten metal, and this part is made up of coaxial bonds. It is characterized by having a large crystal growth region representing a crystal growth structure 36. However, during Intervening regions 36 and 34 are regions 38 of molten metal in which , 110 unidirectional growth is observed. After cooling and solidifying, the metal is isolated and provides the desired target with an angle λ of substantially 0 degrees. used for.

It should be noted in connection with the embodiment of FIG. It has a direction that promotes crystal growth in the direction. For example, the normal clotting process In this case, most of the crystal growth proceeds in the 1.00 direction, and the crystal growth proceeds in the 110 direction. For example, the mold is poured out at an angle of 458 to the 100 direction. Must be.

Coating material is applied to an annular area of a substrate suitable for compact discs. The target used for the selective distribution sputter coating method is as described above. The target is made of atoms (or ions) arranged in a lattice. It is made of FCC metal material. From one surface of the target, a grid The coating material is emitted in a lattice arrangement, the lattice arrangement being A vector in which the most densely spaced atoms extend perpendicularly to the target surface. the direction corresponding to the closest density direction that is oriented at an essentially zero angle to the It is configured to have a tropism vector. Even more preferably, such a case The child structure has a face-centered cubic lattice arrangement in which atoms or ions are selected from the group consisting of aluminum, gold, and platinum atoms. Even more preferable , the atoms consist essentially of aluminum atoms or ions.

When finished, the desired target thickness lies in a line parallel to the close-packed direction of the grid. When measured along the length, it is about 1/4 to 3 inches. These targets are , indicates the envelope of the predicted radiation determined by the large radius and the small radius a, and this In this case, the ratio b/a is greater than 1 and preferably equal to 3.

Generally speaking, to coat an annular area on a desired substrate, the target A directional beam set to emit material selectively from the cut surface. The method for producing the above-mentioned type of sputtering target that appears with crystal lattice deposits is , a furnace that forms a billet of the desired metal material and cuts the billet into a desired length. or forming the billet to the desired length. The billet or The part of the billet is then unidirectionally lengthened to approximately half its initial length. The billet is then machined to the final desired shape. . Preferably, before machining, the billet is heated, and the heating and processing The steps of recessing may be carried out simultaneously in a preferred manner.

Husband Blood Shellfish Cathode sputtering method for compact discs and the characteristics used in this method In order to actually demonstrate the efficacy for targets with a certain crystal structure orientation. , a computer simulation using the Monte Carlo method was carried out, and it was commercially used. Among the possible computer models for compact disc cathode sputtering equipment: , various targets were applied to the aluminum sample to be subjected to simulated sputtering. The crystal structure of the material is used.

The results obtained are shown in Table 1.

Table 1゜ 0 3 44.5 5100 9.1 35 3 33.3 3892 15.645 3 27.2 3818 12 ．． 50 1 32.9 3171 15.3 Note 2) The aluminum code of the CD is the percentage of all sputtered atoms in a particular part of the annular part that has been sputtered. Yes.

Note 3) In the same part as the annular part when used to calculate the data in footnote 2 (collection %) It is the number of atoms in contact per unit time.

Note 4) Uniformity measured in the same annular part as in footnotes 2 and 3. and these same positions, (T, .

Different compactions measured at 8-T1°)/(T, , +T, 1..) Based on comparisons made between discs.

In addition, simulation using the Monte Carlo method requires computation as a single model. It is carried out in connection with the cathode sputtering system of the disc disc, in this case the del b/a, target parameters, and model as indicated in Figures 8 and 9. target/substrate separation parameters are used. These figures are similar to Table 1. The location of the compact disc by sputter coating in the test system In the test system, the target b/a ratio is 3; The crystallographic structure of the target is such that the surface radiation angle λ is substantially zero. ing. As shown in Figures 8 and 9 and Table 1, the compact disc substrate It is expected that a larger amount of aluminum will be deposited on the desired annular region. The target produced with the desired crystal structure direction is For example, even if the target has a crystallographic orientation of <110> direction and this directionality is not parallel to the target surface. It can be seen that a thicker coating is applied to the compact disc.

As shown in the report data in Table 1 and Figures 8 and 9, the <110> way of getting Yuichi The directionality determines the uniform properties of the fold. Regarding the data, the target <110> direction is 45° away from the normal on the surface (standard rolled structure) When moving in a direction parallel to the perpendicular on the surface (cast billet structure), the desired coat sputter deposit thickness across the tinging surface increases. What does this increase in thickness mean? The number of CDs coated using the sputtering target is increased because the material is deposited more efficiently. It is from. Also, a high coating speed means that the coating This means that the disks used can also be expanded.

Targeting by directional radiation (with 110 distinct directions) (see table) The results obtained are 30% higher deposition rate (30% more CD per target). coated, and the uniformity of the thin film is improved from 15.6% to 9.1%. .

This fact means that using a directional sputtering target This makes it easier than using current CD sputtering targets. This means that productivity will increase by 33%.

Although the invention has been described with respect to specific embodiments thereof, this description It is not intended to limit the scope of the invention.6 This invention is not intended to limit the scope of the invention. It also includes modifications, etc., and is limited only by the scope of the claims attached below. It's not something you can do.

20σ Summary book Improved coating particularly suitable for coating on the annular portion of compact discs. Regarding sputtering targets, sputter coats that use the targets Disclosed together with methods of It is. The orientation of the crystal structure of the material of the target is determined by the direction of the crystal structure of the material of the target. The preferred radiation angle of the atoms is determined by the compact disc base to which the coating is applied. oriented substantially perpendicular to the surface of the plate. For those with a specific crystal structure like this The tropism is obtained by unidirectional pressing of aluminum billets.

international search report

Claims (19)

[Claims] 1. The sputter target emits radiation onto an annular area on the surface of the compact disk substrate. Atom or Directionality that corresponds to the close-packed direction perpendicular to the substrate surface, where the ions are closely packed. A coating material consisting of a large number of crystal lattice structures exhibiting vectors is applied to the target. sputtering system and sputtering the target using ions in the sputtering system. Bombardment is performed to release the coating material from the target. and coating the annular region on the surface of the compact disc substrate. , while minimizing the amount of coating material deposited on other areas of the substrate. A sputtering method characterized by comprising the steps of: 2. The target is determined by a large radius b and a small radius a, and b/a is less than about 1. Claim 1 characterized in that it is formed by revealing a large pre-radiation envelope. How to put it on. 3. 3. A method according to claim 2, characterized in that b/a is approximately equal to 3. 4. The coating material emitted from the sputtering target is compacted A method of sputtering an annular region on a surface of a disk substrate; If the material for The method uses the lattice distribution in the direction that occupies the space most densely, generally called the close-packed direction. Arranged atoms or ions are substantially flush with the surface of the substrate within the target. and the FCC metals are aluminum, gold, platinum, copper. , nickel, silver, and palladium, and their alloys A method characterized in that it is a selected metal or alloy. 5. FCC metal is characterized by being aluminum or aluminum-containing base metal. The method according to claim 4. 6. A coating is applied around an annular area of a substrate suitable for compact discs. Used for sputtering coating processes that preferentially distribute coating materials. a sputtering target, wherein the target is arranged in a grid pattern; FCC metal material or alloy consisting of atoms or ions with a coating has one surface from which the material is radiated, and the configuration of the grating is such that the most dense of the grating Atoms or ions occupying space exhibit a directional vector corresponding to the closest-packed direction and the close-packed direction is substantially parallel to a vector extending perpendicular to the target surface. oriented within said target material at an angle of zero to sputtering target. 7. The FCC metals include aluminum, gold, platinum, copper, nickel, silver, and palladium. selected from the group consisting of aluminum and alloys of these metal elements. 7. The target according to claim 6, characterized in that the target is made of a metal. 8. The FCC metals include aluminum, gold and platinum, and from these metal elements. consisting of a metal selected from the group consisting of alloys consisting of The target according to claim 7. 9. Claims characterized in that said FCC metal consists essentially of aluminum. Target according to paragraph 8. 10. a thickness of about 1/4 inch to about 3 inches along a line parallel to the close-packed direction; The target according to claim 9, characterized in that the target has: 11. An envelope of predicted radiation is revealed, and the envelope has a large radius b and a small radius a. , and furthermore, b/a is a value larger than 1. Target according to paragraph 6. 12. A tar according to claim 11, characterized in that b/a is approximately equal to 3. get. 13. Coating an annular area of the substrate suitable for use as a compact disc a specific material configured to selectively emit material from the surface of the FCC metal for application. Sputtering with face-centered cubic (FCC) metals that reveal a oriented crystal lattice A method for manufacturing a target for A billet is formed from the FCC metal, and the billet is unidirectionally pressed. and machining the pressed billet to form the target. A method characterized by finishing the material into a desired shape for use. 14. The billet is heated prior to the machining. The method according to scope item 13. 15. The heating work and the pressing work are performed simultaneously. 14. The method according to claim 13. 16. the heating heating the billet to a temperature of 500 to 800 degrees Fahrenheit; 14. The method of claim 13, comprising: 17. The billet is approximately half of its original height prior to pressing. It is pressed unidirectionally with a force of about 400 to 600 tons. 14. The method according to claim 13, characterized in that: 18. The FCC metals include aluminum, gold, platinum, copper, nickel, silver and para consisting of a metal selected from the group consisting of nickel and alloys of these metals. 14. The method according to claim 13, characterized in that: 19. The FCC metal is made of aluminum or an aluminum-containing alloy. 19. A method according to claim 18, characterized in that: