JPH05125531A - Sputtering deposition apparatus and sputtering cathode - Google Patents

Abstract

PURPOSE: To impart directivity to the release direction of the atoms released from a target by sputtering with a sputter deposition apparatus for forming thin films.

CONSTITUTION: A work 16 and a sputtering target cathode 20 are arranged opposite to each other approximately in parallel in a vacuum chamber 10 of the low-pressure sputter deposition apparatus and a strong electromagnetic field is established by magnetron between both to form plasma 30. This plasma is formed in proximity to the surface of the cathode but apart from the surface of the cathode by a thickness size (d) of the dark part region of the plasma. Plural holes 22 are previously formed in congestion at the cathode over the entire area of its release surface. The aspect ratio h/w (h = depth, w = diameter size) is specified to ≥1.5 so that only the release from the bases of the holes jumps out of the cathode. The min. diameter size of the holes is so set as to be ≤2 times the thickness size of the dark parts, by which the intrusion of the plasma into the holes is averted.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to the deposition of materials for thin film formation. More particularly, the present invention relates to an improved apparatus for thin film forming sputter deposition apparatus, and more particularly to a unique sputter target cathode for use in such sputter deposition apparatus.

[0002]

2. Description of the Related Art The process of forming (or depositing) thin films of various materials is of great importance to the semiconductor industry. Generally, in order to fabricate an integrated circuit having some function, the deposited material is subjected to a pattern forming treatment, which is applied to various lines, pads, vias, or other The structure needs to be related to the function of the integrated circuit. These deposition and pattern forming process steps are a constraint for increasing the circuit density on the integrated circuit. That is, the finer the structure, the higher the density of the integrated circuit, and thus the number of circuits per chip can be increased.

There are three types of methods available for patterning individual structural portions on an integrated circuit. The first is a method using lift-off deposition, the second is a method using reactive ion etching, and the third is a groove / hole filling process (trench and
After the hole filling), a physical or chemical polishing process is performed.

Lift-off deposition is a method of manufacturing a semiconductor device in which a surface mask structure formed in a special shape is removed after a thin film is formed. To form this mask structure, a wafer is generally first coated with a uniform layer of a photosensitive polymer (photoresist). When this photoresist is selectively exposed to ultraviolet light in the form of a pattern on the surface, the exposed portion of the photoresist changes its chemical structure to a slightly different form. A photoresist formed in an appropriate pattern on the wafer surface by removing one of the two types of areas of the photoresist (either the exposed area or the unexposed area) with an appropriate solvent. You can leave the mask made. What is important in this step is that the edge portion of the formed photoresist mask structure has a slightly undercut shape.
The next step is to deposit a uniform thin film layer on both the surface of the wafer and the surface of the photoresist mask. At this time, if the flying directions of the atoms that jump in one after another for deposition are substantially perpendicular to the surface, those atoms do not coat the lower surface of the edge portion of the photoresist mask. .. After this deposition process, the photoresist and the thin film deposited thereon can be removed together by dissolving the photoresist mask in an appropriate solvent. As described above, a deposition forming thin film (deposition) having an appropriate pattern can be formed on the flat surface. What is important here is that the angle at which the deposition flux (flying atomic flux that jumps in to deposit) reaches the surface is extremely close to the vertical, and there is no divergence or gas scattering. Is to keep
These are actually essential, rather than just important. If divergence or gas scattering occurs, the underside of the mask will be coated, thereby
The penetration of the solvent makes it impossible to dissolve the photoresist. In the past, low pressure vapor deposition was generally the only one that could meet the above criteria requirements. In many cases, the deposition method using sputtering does not give satisfactory results. (1) The atoms emitted by sputtering are not vertical emission. , (2) The sputtering source has a certain size, and (3)
A typical sputtering system has a high operating pressure, which causes gas scattering and the like. If any of these influences are applied, the lower surface of the mask structure will be coated.

Recently, two types of devices have been developed which allow a lift-off deposition process to be performed using a sputter deposition system. The first of which is a hollow cathode reinforced magnetron (references 1 and 2), which uses an electron source formed as a hollow cathode to allow the sputtering source to operate under ultra-low pressure. Is. If the sputtering source is small enough and placed far enough away from the work piece, a situation similar to that of the vapor deposition method can be achieved, and thus the lift-off de- vice. You will be able to perform position processing. On the other hand, the second device is a modification of a hollow cathode magnetron, in which a physical collimating mechanism (collimator) is arranged between the sputtering source and the workpiece (Reference 3). ). The collimator is configured as an array of many elongated tubes, which allows only those atoms within the narrow angular range of the sputtered and ejected atoms to move through the collimator. You can do it. With this latter device, lift-off deposition over a large area can be performed using a large sputtering source and with a close distance between the sputtering source and the work piece. ..

The pattern forming method utilizing reactive ion etching (RIE) advances the processing in the reverse procedure of lift-off deposition. In the processing procedure for pattern formation using RIE, first, a uniform thin film is formed on the surface. Any means can be used to form this thin film, the type of which is not important. In the next step, a thin film of photoresist is formed. By selectively exposing the thin film of this photoresist to ultraviolet light and removing a portion of the thin film,
The mask structure can be formed on the surface of the metal thin film formed previously. The reactive ion bombardment method is then used to remove the exposed areas of the previously formed thin film through the open portions of the mask structure. After this step, the remaining photoresist is removed by chemical means to obtain a patterned metal structure in the area covered by the mask structure.

The third pattern forming method is a method which requires the formation of grooves or holes in the surface of the wafer substrate. To engrave those trenches or holes, a technique similar to the reactive ion etching described above may be used. If you have formed a groove or hole,
It is necessary to fill it with an appropriate electrically conductive material, which is often a metallic material. The filling process for this filling must be such that the entire structure of the groove or hole can be completely filled without leaving any cavities, gaps or streaks. When this deposition process is completed, the deposited material is
It is also usually present in the region of the wafer between one groove or hole and the other groove or hole. The next step is to remove, by physical means, the coating that covers such areas. Generally, this removal is performed by polishing, and this physical polishing can be efficiently performed by mixing a weak chemical etching agent into the polishing agent. This polishing method is called chemical corrosion polishing (chemi-etch polishing) in the semiconductor industry.

The deposition process required to fill the grooves or holes must be capable of forming a dense film that contains no cavities or streaks.
Therefore, the chemical vapor deposition (CV) method that is often adopted in the art is
D) and plasma enhanced CVD (PE
It is a technique called CVD). These techniques are
By forming a thin film from the vapor phase on the wafer surface, substantially all the surface is uniformly coated. Therefore, the side surface of the groove or hole is also coated and filled. If this is done properly, only very fine streaks will be left inside the structure such as grooves. However, this type of technique can generally only be performed on a group of metals consisting of a small number of metals due to the complex chemistry involved. The most commonly used metals are tungsten and silicon, but also for aluminum and copper, preliminary research results are beginning to be published.

Physical vapor deposition may also be used to fill the structure of the trench or hole. That is, when physical vapor deposition is carried out under low pressure, the angle at which the atoms reach the surface to which they are attached is perpendicular to the surface, and therefore the structure of the groove or hole is gradually increased from the bottom to the top. Can be filled. However, since the atom in the vapor state reaches the surface at a low velocity, a slight lateral deposition occurs at the top of the side wall of the groove or hole structure, which results in At the outer edge of the structure of the groove or hole, a phenomenon occurs in which the structure of the groove or hole casts a shadow on itself at a slight degree. As a result, a void is formed in the upper portion of the side wall of the groove or hole structure. In addition, physical vapor deposition is generally a type of process that treats multiple workpieces at once, a process referred to in the art as a "batch" process. However, the current trend in the industry is to process wafers one at a time for the purpose of gaining additional control and reducing losses, and thus general However, physical vapor deposition is not a desirable method.

Groove / hole filling using a sputtering method is not easy. The cause is the lift
There is the same problem as listed above regarding off deposition. That is, when an atom is emitted by sputtering, the emission contains non-vertical components, and most of the sputtering
Atoms that fly to the work piece are generally dominated by the fact that the source has a considerable size, and because of the high pressure, gas scattering occurs at a high rate. The velocities are isotropic, that is, their atoms have a large non-vertical component. As a result, a lateral protrusion is rapidly formed in the upper portion of the side wall of the groove or hole. Continued deposition generally causes such sidewalls to grow closer together, thereby introducing voids under the coated film. This void is extremely unacceptable for semiconductor-related applications. Generally, the sputtering method is used
If the groove or hole is very wide and shallow, and the aspect ratio (ratio of depth to width) is
When it is 0.5 or less.

Nevertheless, the sputter deposition method is widely adopted as a method for forming a thin film in the semiconductor industry. Therefore, there is a clear desire to improve the sputtering method so that it can be used for the formation of thin films for both lift-off deposition and groove / hole filling. Can be said to exist. The above-described method of performing sputtering under a low pressure and performing parallelization thereof (Reference Document 3) satisfies these requirements, and in fact, has been successfully commercialized. There is. However, since the collimating mechanism (collimator) is placed between the sputtering target and the work piece, a thick film is deposited on the surface of the collimator, which eventually becomes a strip and falls off. May cause particle contamination of the wafer. Therefore,
This method is improved so that a collimator does not need to be interposed, and the sputtering target is improved so that a thin film suitable for the lift-off method and the groove / hole filling method can be sufficiently used. It would be desirable to be able to form them.

References in the above description are as follows. 1. U.S. Pat. No. 4,588,490 (May 13, 1986)
Sun), inventor: Cuomo et al., Title of invention: "Hollow Cathode Enhanced Magnetron Sputtering
Device) ". 2. Paper, Title: "Hollow cathode reinforced magnetron (Ho
llow Cathode Enhanced Magnetron), Author: J. Cuomo et al., Publication: "Journal of Vacuum Science and Technolog"
y (1986), VolA4, pp. 393-396) ". 3. U.S. Pat. No. 4,824,544 (April 25, 1989)
Sun), inventors: Mikalesen and Rosnagel (Mikale
sen and Rossnagel), title of invention: "Large-area cathode lift-off sputter deposition apparatus (Large
Area Cathode Lift-off Sputter Deposition Device
) ”.

The following references are in addition to the references listed above and are the result of extensive prior art search conducted in the United States Patent and Trademark Office. As will be apparent from the following description, the cited documents have only the property as a general background art, because for forming a thin film on any part of the cited documents, Sputter with a unique configuration that provides a highly directional deposition source
This is because the target has not been suggested.

US Pat. No. 4,834,860 to Demaray et al. Shows a target for a magnetron, which target is provided with grooves in the eroded region of its surface. This groove has an effect on the sputtering voltage and also on the local erosion pattern near the groove. The reason why these influences occur is that the groove changes the local emission form of the electron emission (secondary electron emission) from the cathode surface. Due to this change in the emission form, ion generation in the vicinity of the cathode is caused. The process changes, resulting in different plasma resistances.

Another important function of this groove is that it erodes and changes its shape over time. In essence, the entirety of this U.S. Pat.
This is based on the fact that the erosion pattern of the normal part (the part where the groove is not formed) of the cathode is changed. As a result, the total amount of material that can be sputtered and released from the cathode is 20 to 20 before the cathode penetrates to the back surface due to erosion.
30% increase. This etch "track" improvement is the subject of the basic claims of this US patent.

In comparison with the present invention, this US patent
It can be said that it is not related to the release distribution form of particles. In contrast, the focus of the present invention is to allow the "emissive morphology" of sputtered atoms to be controlled by the microscopic (small size) structure of the cathode surface. Among the atoms emitted from the bottom surface of the deep-shaped structure, those which do not move in a direction nearly perpendicular to the surface are collected by the side wall of the structure. The invention therefore particularly relates to a filtering action of this kind for sputtered and ejected atoms. In order to obtain this filtering effect, it suffices to provide a structure having a relatively deep shape composed of a plurality of holes and to emit atoms from the bottom surface of the structure by sputtering.

US Pat. No. 4,610,774 by Sakata et al., Describes an "alloy" target, namely 2.
It is clear that the purpose is to control the composition of the component target. The specification of this U.S. patent describes a plurality of permutation aspects, which are basically of the same geometry. This U.S. patent seeks to control the composition of a target composed of two different materials (A and B) for long life. According to this US patent, one of the two materials is formed in the shape of a wide groove (V-shaped groove), the reason for doing this is
This is because it is possible to affect the long-term stability of the emission of atoms from the groove region.

There are some distinct differences between this US patent and the present invention. First of all, the structure disclosed in this U.S. patent is not particularly interested in performing the deposition process in alloy mode. A target composed of only a single component may be used, or an alloy target may be used. The purpose is to form a thin film having the same composition.
Second, the dimensional size of structures such as grooves in the U.S. patent of Sakata et al. Is extremely large. That is, when the plasma enters the groove, its direction is tilted, thereby controlling the erosion of the material and achieving a long life. In this regard, it can be said that the US patent of Dimaray et al. Third, when the cathode of the Sakata et al. Patent operates, the plasma erosion region is generally divided into a material A region and a material B region.

The present invention is different in any of the points pointed out above. First, the present invention is not related to alloys that are adapted to control relative proportions. Second
Moreover, the present invention does not allow the plasma to penetrate into the surface structure of the cathode. On the contrary, on the contrary, it is important to prevent the plasma from entering the cathode pores. And third, the present invention does not include an etch track.

US Pat. No. 4,637,853 to Bumble et al. Shows a hollow cathode in the form of a "bucket", provided that it is not a sputter target and the plasma is in its bucket or The requirement is to be present "inside" the hole. When the plasma enters the hole, the plasma density locally and significantly increases in the hole, and the intensity of ion bombardment on the inner wall surface of the bucket locally increases correspondingly. The side wall of the bucket is
It has a relatively large area compared to the bottom of the bucket. The atoms sputtered and ejected from the side wall of the bucket are mainly deposited on the surface of the side wall opposite to the bucket. Only a very small part of those atoms is intended to reach its purpose, and the actual distribution can be calculated.

The decisive difference between this US Pat. No. 4,637,853 and the present invention is that the present invention ensures that the plasma never enters the pores. The holes are made small so that plasma cannot enter. The dark portion, that is, the plasma self-shielding distance (thickness of the outer shell region) is set to be larger than the size of the hole. Therefore, there is no hollow cathode reinforcement as in the case of buckets. On the other hand, in this U.S. patent, it is important that the plasma is allowed to enter the holes.

[0022]

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to
It is an object of the present invention to provide a sputtering processing apparatus which has been significantly improved. Also, as another purpose, it is possible to generate a deposition source having high directivity,
Sometimes we provide such a device. A further object of the present invention is a sputtering target cathode structure, wherein the emission distribution morphology of the emission from its surface generated during the sputtering is modified due to the unique structure of the target cathode. Another object of the present invention is to provide a sputtering target / cathode structure having an emission distribution morphology. A further object of the present invention is a sputtering target of that kind, which has a remarkable thin film forming ability by making the emission form of the target substantially perpendicular to the surface of the target. The present invention is to provide a sputtering target.

The above objects of the present invention are generally achieved by a low pressure thin film sputter deposition apparatus adapted to operate at a pressure of 0.5 mTorr or less. The processing by this apparatus is carried out in a vacuum state of a chamber equipped with a means for introducing an ionizable gas. This device comprises means for establishing a strong electromagnetic field, such as a magnetron or an RF dipole tube, the electromagnetic field establishing means being an anode, or a wall of a chamber which can function as an anode,
It is arranged between the sputtering target and the cathode. The electromagnetic field causes a plasma of ionized gas to form close to the cathode surface, but away from the cathode surface by a dark area having a thickness of d. The cathode has a flat surface that is not curved or warped, and is disposed in the processing chamber so as to be substantially parallel to the surface of the structural portion of the workpiece. The cathode further comprises a plurality of closely-spaced and continuously formed holes throughout its emission surface.
The holes have an aspect ratio h / w (h = depth, w
== Handover) is 1.5 or more. Also, the holes are very densely packed and the spacing between adjacent holes is small, close to the limit where the strength of the structure can be maintained, about 0.02 inches. It is about 5 mm. The minimum passing dimension w of the holes is set to be equal to or less than twice the thickness dimension d of the dark portion, which is the distance (d) determined by the parameters of each deposition process.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a modification of a conventional sputtering target cathode which can be used in a sputtering method using plasma or an ion beam sputtering method. Generally, this type of target has a flat planar surface. When carrying out a plasma-assisted sputtering process, this kind of target also serves as the cathode for generating the plasma. When the plasma contacts the target / cathode, a thin shell or dark portion is formed at the contact interface. Ions from the plasma are accelerated across this dark space and strike the cathode at high velocity, which expels surface atoms. On the other hand, in the ion beam sputtering apparatus, the target is simply a material placed in the ion beam emission path. When the ions in the beam strike the surface at high velocity, the surface atoms are similarly ejected.

According to the present invention, a target having a flat surface is remodeled, and the target surface is machined,
Alternatively, it is an array composed of a plurality of relatively deep structures formed by another method. A generally required requirement in the plasma-based sputtering method is that the cross-sectional dimension of the structures is not more than twice the thickness of the dark portion or outer shell portion of the plasma. .. If this condition is met, the plasma cannot penetrate into the structure. Ions from the plasma are accelerated across the outer shell,
Mainly, it collides with the bottom surface of the structure formed on the surface of this target. On the other hand, the corresponding ion beam
In the case of the sputtering method, the direction of the ions from the ion beam is approximately perpendicular to this target so that they also strike the bottom surface of the structure on the surface of the target. You can

The emission distribution of the atoms sputtered and emitted from the bottom surface of this structure of the sputter target is the same as the normal emission distribution of the atoms sputtered and emitted from other ordinary surfaces. , Which is usually called the "cosine" distribution. However, the side wall portion of the structure having a deep shape acts to limit the emission angle of atoms that can actually fly out from the target. That is, if an atom is emitted vertically, the atom can escape through the opening in the structure. On the other hand, when the atom is ejected at an angle that is far from the vertical, the atom is collected by the inner wall of the structure.

The aspect ratio of this structure on the cathode surface determines the emission distribution of the emitted atoms. An important requirement in this regard is that in a plasma-based sputtering method, the crossover dimension of the openings must not exceed twice the thickness dimension of the outer shell or dark portion of the plasma. In the sputtering method using an RF diode or a DC diode, the thickness of the dark portion is about several millimeters to about 1 centimeter depending on the pressure condition and the discharge output condition. Further, in the case of deposition using a magnetron, the thickness of this dark portion is about 0.5 to 1.5 mm.

By using this modified cathode, the emission distribution can be changed significantly, which is possible by absorbing non-vertical components of the atoms that fly out to deposit on the surface of the cathode. Because it will be. A further requirement of this improved deposition method is that the pressure in the chamber in which the sputtering is carried out is low so that sputtered atoms do not undergo vapor phase collisions while flying from the sputtering target to the wafer surface. There is a thing to leave.
If such a collision occurs, the vertical orientation is lost, so that in the case of lift-off processing,
The lower surface of the mask is coated, and the groove /
Voids are formed in the hole filling process. For most of the various plasma-assisted sputtering methods, this requirement requires that the plasma be enhanced so that it can function at low pressures (below 0.5 mTorr). Nothing else. One of the methods for this strengthening is to use a hollow cathode, as described above (References 1 and 2). However, it is also possible to use other plasma sources than the hollow cathode, with a special design. The special requirement in that case is that the mean free path of the sputtered atoms is longer than the distance from the target to the work piece. Therefore, as long as the operating pressure can be reduced to a range of 0.5 mTorr or less, various magnetron devices can be used as they are, and for example, electron cyclotron resonance (Electron Cyclotron Resonanc
Other devices such as e: ECR) plasma devices can also be used.

Preferred embodiments will be described below with reference to the drawings. Referring to FIG. 1, the figure shows a schematic cross-sectional view of a low pressure sputter deposition apparatus. The process performed using this apparatus is performed while the chamber 10 connected to an appropriate vacuum pump via the port 12 is in a vacuum state. As the plasma forming gas, for example, argon or the like is used, and this is used.
It is introduced through the opening 14. The work piece 16 to be coated is placed on a suitable support structure 18 connected to the same potential as the chamber 10. The sputter target cathode 20 is arranged at a position slightly apart from the workpiece 16 so as to be in a posture substantially parallel to the workpiece 16. On the surface of this cathode 20,
A plurality of small holes 22 are drilled all over the emission surface. Therefore, the bottom surfaces of the plurality of holes 22 are
The emission that forms the emission surface of the cathode and, as already explained, the emission emitted from the bottom surface of the plurality of holes 22 is an emission substantially perpendicular to the surface of the cathode. In addition, a water jacket 24 is provided to cool the cathode during operation. The water jacket 24 has an inlet and an outlet for cooling water, which are not shown for the sake of clarity.

A power supply is provided and is designated by the reference numeral 26. This power supply may be simply a high voltage DC power supply or an RF power supply. This power supply enables the device to operate as a normal dipole plasma device. Further, as indicated by reference numeral 28, a hollow cathode is provided at a position close to the cathode 20. This hollow cathode 28
Is to enhance plasma formation under low pressure, and in this regard, US Pat.
As described in No. 588490. Reference numeral 30 indicates a plasma of ionized gas. This plasma is separated from the cathode 20 by a distance d.
As described above, the portion of this distance d is the dark area. The specifics of these should be determined according to the type of material used for the deposition and the details of the processing procedure executed by this apparatus. Still further, the adoption of hollow cathode reinforcement, although preferred, is not absolutely necessary. On the other hand, the pressure of 0.5 mTorr or less is necessary for the processing procedure executed by this apparatus.

Referring to FIG. 2, this figure shows a detailed structure of a small portion of the cathode structure in a sectional view and also shows a part of the outer shell-like region of the plasma. The gap between the closest position of the shell-like region and the cathode is illustrated. This gap is called the dark part d. As described above, it is important for the present invention that the dark portion d exists, that is, that the plasma does not penetrate into the holes, and furthermore, the minimum crossover of the holes of various shapes. The thickness dimension of the dark portion d is important in determining the dimension.

FIGS. 3A, 3B, 3C, and 3D show some types of pore structures, or pore shapes, that are sufficient to provide the directed emission function taught by the present invention. FIG. FIG. 3A shows a structure composed of a plurality of cylindrical holes which are formed extremely densely and densely and continuously, and this structure is produced by, for example, drilling or other fine cutting. You can B, C, and D of FIG.
Is a square, rectangular, and hexagonal continuous hole, and these structures are produced by, for example, the electronic erosion cutting method or the ultra-precision casting method. can do.

FIG. 4 is a detailed view of the smaller portion of the embodiment of FIG. 3A showing the dimension w.
This dimension w must be less than twice the thickness dimension of the dark portion, and the dark portion is the distance from the surface of the cathode to the plasma as described above.

FIG. 5 is a more detailed view of the arrangement of FIG. 3B consisting of a plurality of square holes that are closely packed and formed in series. Also in this configuration, the dimension w is determined so as to be not more than twice the thickness dimension of the dark portion.

In both FIGS. 4 and 5, the spacing between the holes, ie the dimension s of the wall thickness, is an absolutely small value, so that the emission from the surface relative to the total emission from the cathode is small. We try to keep the volume ratio as small as possible. In general, this wall thickness dimension should be as thin as the cathode fabrication method allows, in which case practically it will be on the order of 0.02 inches (0.5 millimeters). Is known.

The following are suitable processing parameters when the sputter deposition apparatus using the unique target cathode of the present invention disclosed herein is used in the system shown in FIG. It is a value found to be present. Pressure range: 0.001-0.5 mTorr Plasma generating gas: Argon is preferred,
Other suitable processing gases work equally well. Energy source: magnetron, DC dipole, R
F dipole magnetron output: maximum 30 kW dark space thickness: 1-10 mm, 0.5
Preferably close to millimeters Aspect ratio of holes: h / w ≧ 1.5 Hole dimensions: w = 1 to 2 millimeters (where w is the minimum across dimension of each shaped hole)
Depth = 3-6 mm Hole spacing: s ≤ 0.02 inch (0.5 mm)

If all of the above criteria are met, the ions from the plasma will hit the bottom surface of the cathode whatever the surface structure of the cathode is. Then, the side wall portion of the surface structure collects, from the atoms emitted by sputtering (from the bottom surface of the hole of the structure), the atoms that are not emitted at an angle close to perpendicular to the surface of the cathode. Of the materials (atoms) that are sputtered and emitted, all that has not been recovered becomes a beam having a high degree of directivity and jumps out from the cathode, and this beam collides with the workpiece. This gives all the advantages of this process, which have already been explained.

The various examples disclosed herein for the shape of the holes are what are considered to be the best choice. However, as will be readily appreciated, other shapes may be employed, such as a pentagon,
It can also have an octagonal shape or the like. Still further, the criterion for obtaining effective directional emission is that, as described above, in a hole having an arbitrary shape, the minimum crossover dimension w of the hole is
The thickness of the dark portion is not more than twice the thickness dimension, and the depth of the hole is at least 1.

It has been found that the cathode described above can be used in a variety of systems that require a cathode sputtering target, and that it is a good alternative to different types of targets, for example planar targets. The directional sputtering carried out by means of the following has proved to be a significant improvement.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an apparatus for performing an improved sputter deposition process.

FIG. 2 is a cross-sectional view taken along the cross-section through the sputtering target cathode to illustrate the important dimensions associated with the cathode structure and the ionizing plasma.

FIG. 3A is a plan view of a preferred embodiment of the present invention having a plurality of cylindrical holes that are densely and continuously formed, and B is a plan view of the present invention in which each hole has a square sectional shape. FIG. 6 is a plan view of another embodiment, C is a plan view of yet another embodiment of the present invention in which the cross-sectional shape of each hole is rectangular, and D is the present invention in which the cross-sectional shape of each hole is hexagonal. It is a top view of another example of further.

FIG. 4 is a detailed view of the structure shown in FIG. 3A for explaining important dimensions.

FIG. 5 is a detailed view of the embodiment of the present invention shown in FIG. 3B, illustrating important dimensions in the structure of this alternative embodiment.

[Explanation of symbols]

 10 chamber 12 port 14 gas introduction opening 16 workpiece 18 support structure 20 sputter target cathode 22 hole 24 water jacket 26 power supply 28 hollow cathode 30 plasma

 ─────────────────────────────────────────────────── ————————————————————————————————————————————————————— stephenmark Rosnagel Inventor Stephen Mark Rosnagel 11 North Manor Drive, White Plains, NY 10603, USA

Claims (9)

[Claims] 1. A sputter-deposition apparatus used for low-pressure sputter-deposition processing, a means for exhausting from a processing chamber to establish a vacuum of 0.5 mTorr or less in the chamber; Means for introducing an ionizable gas, and means for establishing a high-intensity electromagnetic field between the anode and the sputtering target cathode, both arranged in the chamber The electromagnetic field is a region of plasma of ionized gas,
Close to the cathode, but at a distance d from the cathode
The cathode has a flat surface and is provided with a plurality of closely-spaced and continuously formed pores over its entire emission surface. And the plurality of holes have an aspect ratio h / w (here, h / w)
= Depth, w = across dimension) is at least 1.5
And the spacing between the holes is as wide as necessary to maintain the physical strength of the cathode as a structure, and the holes have their minimum crossover dimension (w), The thickness dimension of the space between the ionization region of the plasma and the surface of the cathode should be less than twice the thickness dimension of the dark part to prevent ionized plasma from entering the holes. Also, the sputter deposition apparatus, wherein the emission from the cathode is mainly from the bottom surface of the hole. 2. The sputter deposition apparatus according to claim 1, wherein the energy source for ionization comprises a magnetron. 3. Sputtering apparatus according to claim 1, characterized in that the energy source for ionization comprises an RF dipole tube.
Deposition device. 4. A sputtering cathode for use in a low pressure (0.5 millitorr or less) sputter deposition apparatus, wherein a plasma of ionized gas is not ionized proximate to the cathode but from the cathode. In a sputtering cathode formed with a thickness d of the dark space, the cathode has a flat surface and a plurality of closely-spaced and continuously formed holes over its entire emission surface. And the aspect ratio h / w (where h
= Depth, w = across dimension) is at least 1.5
And the spacing between the holes is as wide as necessary to maintain the physical strength of the cathode as a structure, and the holes have their minimum crossover dimension (w), The thickness dimension of the space between the ionization region of the plasma and the surface of the cathode should be less than twice the thickness dimension of the dark part to prevent ionized plasma from entering the holes. And a sputtering cathode, wherein the emission from the cathode is predominantly from the bottom surface of the hole. 5. The sputtering cathode used in the low pressure sputtering apparatus according to claim 4, wherein each of the plurality of holes has a circular cross-sectional shape. 6. The sputtering cathode used in the low pressure sputtering apparatus according to claim 4, wherein each of the plurality of holes has a square cross-sectional shape. 7. The sputtering cathode for use in a low pressure sputtering apparatus according to claim 4, wherein each of the plurality of holes has a hexagonal cross-sectional shape. 8. The sputtering cathode used in the low pressure sputtering apparatus according to claim 4, wherein each of the plurality of holes has a rectangular cross-sectional shape. 9. The distance between adjacent pores of the plurality of pores on the surface of the cathode is about 0.02 inch, which is the minimum value for structural stability.
The sputtering cathode used in the low-pressure sputtering apparatus according to claim 4, wherein the sputtering cathode has a diameter of about 05 mm.