TWI527924B - Magnetron with controllable electromagnetic field - Google Patents

Description

Electromagnetically controlled sputtering cathode

The invention relates to a sputtering target device, in particular to a permanent magnet, a magnet and a magnetic coil disposed behind the sputtering target, and the position of the electromagnetic coil and the current introduced into the coil are changed to reach the magnitude of the changing magnetic field. The purpose of changing the position of the plasma is achieved, and the purpose of improving the utilization rate of the target is achieved.

Magnetron sputtering refers to the arrangement of an electromagnet or a permanent magnet behind a sputter target in a vacuum sputtering chamber to generate a magnetic field and cause the magnetic field line to penetrate from the rear of the target to the front of the target, and then return to the target. Electromagnet or permanent magnet at the rear of the material. The plasma generator utilizes the guidance of the magnetic field to bombard the predetermined region of the metal target to knock out the metal atoms, and then deposits metal atoms on the surface of the workpiece below the target to form a thin film. The plasma gas may contain an inert gas such as argon or a reaction gas that can react with the target.

The result of this will cause the target to form an electron trap like a tunnel-like structure. This effect is further enhanced when the tunneled electron trap is further strengthened after the metal target forms a closed loop. However, it causes the plasma to form a loop, causing the target to be tunnel-like, which results in the disadvantage that the utilization of the target is significantly reduced.

Therefore, a sputtering target of a movable magnetic field, such as Japanese Patent JP 63-247366 designs a movable annular target to achieve uniform reduction of the target surface. Another Republic of China patent No. I299365. A sputtering apparatus and method for moving a target is disclosed. This device requires a linear motor to drive the target.

A further embodiment of the prior art can be found in the Republic of China Patent No. I391514, the magnetron sputtering target disclosed in this patent, see the perspective partial cross-sectional view shown in FIG. Referring to FIG. 1 , a magnetron sputtering machine 200 includes a carrier 210 , a magnet group 220 , an internal coil 230 , an external coil 240 , an intermediate magnetic ring 250 , a target 260 , and a conductive magnet ring . 270, the magnet group 220 is disposed on the bearing surface 211 of the carrier 210 to provide a magnetic field source, and the inner coil 230 is wound around a permanent magnet 221. The outer side of the permanent magnet 221 further includes an outer magnet ring 222. The inner coil 230 is wound around the permanent magnet 221 to enhance the magnetic field source. The inner coil 230 has a preferred number of turns of about 40 匝, and the outer coil 240 is disposed outside the magnet group 220. The position of the lowest point of the axial magnetic field is changed, and the number of turns of the outer coil 240 is about 900 匝. The intermediate magnetic ring 250 is disposed between the permanent magnet 221 of the magnet group 220 and the outer magnet ring 222 to enhance the magnetic field in the middle and change The size of the magnetic field in the magnetron sputtering machine 200 is disposed on the first surface 261 of the target 260 to radially guide the magnetic field lines of the magnetic field such that the magnetic field direction is parallel to the target 260. The magnet ring 270 corresponds to the intermediate magnetic ring 250. The outer magnet ring 222 is taller than the intermediate magnetic ring 250. An element such as the intermediate magnetic ring 250, the magnetizing ring 270, and the outer coil 240 is used to achieve that the direction of the magnetic flux is not excessively concentrated in a portion of the target 260, causing the target 260 to be etched through to improve the target 260. The purpose of the term of use.

A further embodiment of a prior art sputtering target can be found in U.S. Patent No. 6,337,781, issued to Sichmann et al. Please refer to FIG. 2 for a structural diagram of a half cathode (including a target), and the other half of the cathode (including the target) and the structural diagram of FIG. 2 are mirror-symmetrical with respect to the rotary axis 44 (not shown). ). As shown in Fig. 2, the structural view of the half cathode includes a first yoke yoke 21 and a second yoke yoke 21' which are connected by a permanent magnet 9. The second yoke iron 21' is in turn coupled to a shoe-type magnetically permeable material 14. The bolt 20 is connected to the first yoke iron 21.

A space between the first yoke yoke 21 and the second yoke 21' is accommodated with a sputtering target 8, and two coils 76, 77 are provided above the sputtering target 8. Between the two coils 76, 77 is a core which also provides a shielding function for the magnetically permeable material, which shields the target space (the gap between the target and the substrate 27 to be sputtered) 84 against the permanent magnet 9 The short circuit magnetic field lines of the magnets (shelds the target space 84 against the short circuit magnetic field lines of the magnet 9), therefore, the magnetic field changes can be generated by injecting a relatively low current into the electromagnetic coil. Figure 2 also shows the corresponding magnetic field line distribution.

The above-mentioned prior art eliminates the driving means for moving the target, but has external and inner ring permanent magnets (their heights are different) and inner and outer ring electromagnets. The electromagnet has no cooling device.

In view of the above, an object of the present invention is to provide a technique for using an inner and outer permanent magnet and a coil of electromagnetic coil to change the current introduced into the coil to achieve the purpose of changing the magnetic field, thereby further expanding the target surface erosion range of the target. Effectively eliminates uneven erosion of the target surface, especially the green coating of the target side can be more uniform.

It is an object of the present invention to provide a magnetron sputtering cathode which can control the current magnitude and period of the coil to be displaced to achieve the purpose of improving the utilization of the target.

The magnetron sputtering cathode disclosed in the present invention comprises a magnetron sputtering cathode comprising at least: a magnetically conductive substrate; a closed first permanent magnet ring seated on a periphery of the magnetically conductive substrate; and a second permanent magnet Sitting at the center of the magnetically permeable substrate, the N-pole of the second permanent magnet and the first permanent magnet are opposite to the target surface; a closed electromagnetic coil is disposed on the magnetically permeable substrate and is opposite to the second permanent magnet . The electromagnetic coil is adjacent to the first permanent magnet ring, and the electromagnetic coil The introduced current period changes to change the position of the plasma mass to bombard the target; the electromagnetic coil ranges from the periphery of the target to two-thirds of the target width; a cooling copper bottom plate is disposed on the second permanent magnet strip, the first permanent a space surrounded by the magnet ring and on the closed electromagnetic coil; and a target disposed on the cooling copper base plate. The cooled copper substrate is supported by at least one support post on the magnetically permeable substrate.

In another embodiment, the magnetically permeable substrate has a unit step shape, that is, a platform is provided at the intermediate portion, a second permanent magnet may be disposed at the center of the platform, and the other portion of the platform supports the cooling copper base plate (the support column is omitted). As in the first embodiment, the first permanent magnet is on the periphery of the entire magnetic conductive substrate, and the N poles (magnetic north poles) of the first permanent magnet and the second permanent magnet are opposite with respect to the target surface. Computer simulation experiments show that the current cycle change introduced by the electromagnetic coil can change the position of the plasma mass. According to the technology provided by the present invention, the position of the plasma mass moves by the current change by at least 35% compared with the known technology (Sichmann). The amount of movement, therefore, plasma efficiency can be increased by more than 10%.

200‧‧‧Magnetic Sputtering Machine

210‧‧‧ Carrier Board

230, 76, 77‧‧‧ internal coil

220‧‧‧ Magnet group

150, 240‧‧‧ external coil

250‧‧‧Intermediate magnetic ring

8, 140, 260‧ ‧ targets

270‧‧‧Guide magnet ring

211‧‧‧ carrying surface of the carrier

9, 221‧‧‧ permanent magnet

222‧‧‧External magnet ring

261‧‧‧ the first surface of the target

44‧‧‧Rotary axis

21‧‧‧First yoke iron

21’‧‧‧Second magnetic yoke

100'‧‧‧ Platform part of the magnetically conductive substrate

14‧‧‧Shoe type magnetically permeable materials

20‧‧‧ bolt

27‧‧‧ Spilled substrate

84‧‧‧ Target space

100‧‧‧magnetic substrate

110‧‧‧First permanent magnet

120‧‧‧Second permanent magnet

130‧‧‧Cooled copper substrate

160‧‧‧Cooling line

170‧‧‧Electric pulp group

180‧‧‧Target magnetic field line level

175‧‧‧ arrow direction

190, 191, 192‧‧‧ magnetic flux density versus distance curve `125 support

90, 91, 92‧‧‧ are the surface distribution curves of magnetic flux density targets of currents 0A, 14A, and -14A, respectively

1 shows a conventional sputtering cathode; FIG. 2 shows a conventional sputtering target structure and a magnetic line path; FIG. 3A shows a schematic diagram of a sputtering target designed according to the first embodiment of the present invention; FIG. 3B shows a schematic diagram of the sputtering target according to the present invention; A top view of a sputtering target structure designed in a first embodiment; FIG. 3C shows a cross-section of a sputtering target structure designed in accordance with a second embodiment of the present invention 4A, FIG. 4B and FIG. 4C respectively show the position of the plasma ball of the sputtering target of the present invention at zero current, low current and high current of the electromagnetic coil; FIG. 5A, FIG. 5B and FIG. The magnetic flux path simulated by the sputtering target electromagnetic coil current I=0, I=14A and I=-14A; FIG. 6 shows the moving distance of the plasma generated by the sputtering target of the present invention caused by the change of the electromagnetic coil current; Fig. 7 shows a conventional sputtering target (structure of a half cathode).

8A, 8B, and 8C show magnetic field line simulation results of a conventional sputtering target with coil currents of 0, 14A, and -14A, respectively.

9A and 9B show, according to still another embodiment of the present invention, the electromagnetic coil is located at different positions on the magnetically permeable substrate, and the position of B ⊥ = 0 varies with the position of the electromagnetic coil.

In order to make the above objects, features and advantages of the present invention more comprehensible, a preferred embodiment of a magnetron target designed in accordance with the present invention, together with the accompanying drawings, is described in detail below.

3A is a schematic cross-sectional view of a toroidal or magnetron sputtering target according to a first embodiment of the present invention. A magnetically conductive substrate 100 has a closed first permanent magnet ring 110 mounted on the periphery of the magnetically permeable substrate 100. A second permanent magnet 120 is seated in the center of the magnetically permeable substrate. The second permanent magnet 120 may be a magnet strip or a magnet that may be a closed loop. The second permanent magnet 120 and the N pole of the first permanent magnet ring 110 are opposite to each other with respect to the target surface. That is, when the magnetic pole of the first permanent magnet ring 110 facing outward is the N pole, the magnetic pole of the second permanent magnet 120 facing outward is the S pole. On the other hand, when the magnetic pole of the first permanent magnet ring 110 facing outward is the S pole, the magnetic pole of the second permanent magnet 120 facing outward is the N pole. A closed electromagnetic coil 150 is disposed on the magnetic conductive substrate 100. In a preferred embodiment, the electromagnetic coil 150 is as close as possible to the first permanent magnet ring 110. That is, at the outer edge of the target. The electromagnetic coil 150 ranges from the outer edge of the target to the 2/3 target width; the cooling copper bottom plate 130 (the cooling water line is not shown) is disposed in the space surrounded by the second permanent magnet 120 and the first permanent magnet ring 110. And supported by a support column (or support base) 125 on the electromagnetic coil 150. A target 140 is disposed on the cooling copper base plate 130. The height of the support post 125 is comparable to or slightly higher than the height of the electromagnetic coil 150.

Figure 3B shows a top view taken in accordance with a first embodiment of the present invention. FIG. 3B shows that the first permanent magnet ring 110 is seated on the magnetic conductive substrate 100, then the electromagnetic coil 150 and the support post 125. In the middle is the second permanent magnet 120, which is also a magnet ring, and the cooling copper base plate 130 is Located on the support column 125.

In the present invention, the shape of the magnetic conductive substrate 100 is not particularly limited. For example, in another embodiment, as shown in FIG. 3C, the cooling copper base plate 130 for facilitating simultaneous cooling of the electromagnetic coil 150 and the target 140 may not be required. In particular, under the support column 125, and simple support is obtained, the magnetic conductive substrate 100 can be formed in a stepped shape, that is, the middle portion has a higher platform 100', as shown in FIG. The first permanent magnet ring 110 is seated on the periphery of the magnetic conductive substrate 100; a second permanent magnet 120 is seated in the middle of the magnetic conductive substrate platform 100'. A magnetically permeable substrate platform 100' can be used to support the cooled copper substrate 130. An electromagnetic coil 150 is disposed beside the magnetic substrate platform 100'. And the magnetic substrate platform 100' Below it is provided a cooling line 160.

The electromagnetic coil 150 is supplied with current by a power supply. (The forward and reverse currents alternately change. The present invention uses the current introduced into the electromagnetic coil 150 to periodically change, and cooperates with the first permanent magnet ring 110 and the second permanent magnet ring 110 and The magnetically permeable substrate 100 can reach the moving magnetic field, thereby achieving the purpose of moving the position of the plasma regenerator, so that the plasma bombards the target 140 in a wide range of movement, and the target is consumed on average.

Utilizing the imported direct current to the electromagnetic coil 150 of the magnetron sputtering target will change the dense position of the plasma mass 170, please refer to FIG. 4A to FIG. 4C. When the current is 0 and the low current is increased to a high current, the plasma mass 170 is brought closer to the center of the target (the position away from the electromagnetic coil 150) from the target outer ring (the position where the electromagnetic coil 150 is located).

In addition, with a coil current = 0A (amperes), 14A and -14A, a copper coil with a wire diameter of 2 mm, the number of coils 230, under the above conditions, the magnetic field path changes caused by the analog coil current, please refer to Figure 5A (I = 0) Figure 5B (I = 14A) and Figure 5C (I = -14A).

When (I = 0), the magnetic lines of force are concentrated at the first permanent magnet 110 and the second permanent magnet 120, as shown in Fig. 5A.

When (I=14A), the magnetic lines of force are affected by the coil and the compression deformation is concentrated on the first permanent magnet 110, and the compression direction is as shown by an arrow 175 in FIG. 5B (the first permanent magnet 110 faces the target surface and the second permanent magnet 120). . The horizontal line of the target magnetic field line 180 (the vertical component of the magnetic field B ⊥ = 0) is on the inner side (the position where the second permanent magnet 120 is located).

When (I=-14A), the magnetic lines of force are affected by the coil and the compression deformation is concentrated on the first permanent magnet 110 and the second permanent magnet 120, and a compression direction is also generated as indicated by an arrow 175 in FIG. 5C (by the Z-shaped yoke) The iron 100, 100' junction faces the target surface and the first permanent magnet 110). The target magnetic field line level 180 moves to the outside (the position where the first permanent magnet 110 is located).

Please refer to the relationship between the magnetic flux density and the surface distribution of the target, and 90, 91, and 92 are the simulation curves of coil current changes 0, 14A, and -14A, respectively. The relationship diagram is drawn according to the magnetic field line diagram of FIG. 5. The figure shows the area where the vertical component of the magnetic field B ⊥ = 0, and the range of the guided plasma movement can be as long as 38.6 mm due to the change of the coil current 0, 14A, -14A. .

In addition, in order to compare the difference between the cathode structure disclosed by the present invention and the cathode structure disclosed by Sichmann, the present invention is additionally simulated by the cathode structure disclosed by Sichmann, and the half cathode structure disclosed by Sichmann is shown in FIG. 8A, 8B, and 8C show simulation results when the coil currents are 0, 14A, and -14A, respectively. According to the simulation results, the plasma movement range can be determined to be 26.4 mm.

Table 1 compares the Sichmann cathode target with the cathode target of the present invention in the plasma movable range (A), magnetic flux (B), and plasma moving efficiency A/B.

From the above simulation results, it is understood that the cathode target of the present invention can achieve a higher plasma moving range and a plasma moving efficiency.

In the above embodiment, the electromagnetic coil 150 is in the range of the edge of the target to two-thirds of the target width. It is the best embodiment. In a preferred embodiment of the invention, the position of the electromagnetic coil 150 is biased toward the inside of the target, which will cause the position of the magnetic field B ⊥ = 0 to be shifted inwardly, see FIG. In other words, the position of B ⊥ = 0 varies with the position of the electromagnetic coil.

The invention has the following advantages:

(a). Only one closed electromagnetic coil is required, and the electromagnetic coil is enclosed in the Z-shaped (i.e., the unit step shape described above) of the cooling copper plate, and the magnetic conductive substrate 100, 100' is placed in the accommodating space generated by the first permanent magnet 110. Therefore, the cooling copper plate can both cool the coil and cool the target.

(b). The magnetic field of the conventional technology sputtering machine passes through the bottom of the target into the cavity, and the thickness of the target is limited to about 1 cm, so as not to affect the magnetic field strength. The magnetic field of the invention is traversed from both sides of the target, and the planar metal target with good heat dissipation can reach a thickness of 3 cm.

(c) Compared with the conventional technique of Sichmann, the plasma moving range of the present invention is increased by 35% compared with the prior art, and therefore, the plasma moving efficiency can be increased by more than 10%, and the target can be more uniformly consumed and improved. Target utilization.

(d). Some conventional techniques require a mechanism for displacement or rotation of the magnetron mechanism. The present invention does not require such a mechanism, and it is only necessary to vary the coil current magnitude and period to achieve an effect of improving the utilization of the target. The mechanism without displacement or rotation makes the structure simple, easy to seal the vacuum, and convenient for maintenance.

(e) The overall structure can be applied to magnetron sputtering and arc ion plating, while magnetic field regulation can increase the moving rate and range of the arc spot on the target surface and reduce the occurrence of droplet particles.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the present invention should be included. Within the scope of the patent application.

100‧‧‧magnetic substrate

110‧‧‧First permanent magnet

120‧‧‧Second permanent magnet

130‧‧‧Cooled copper substrate

160‧‧‧Cooling line

140‧‧‧ Target

Claims (8)

A magnetron sputtering cathode comprising at least: a magnetically conductive substrate; a closed first permanent magnet ring seated on an outer circumference of the magnetically conductive substrate; and a second permanent arrangement a magnet ring is disposed on a center line of the magnetic conductive substrate, wherein the second permanent magnet and the N pole of the first permanent magnet are opposite to the target surface; the closed electromagnetic coil is disposed on the magnetic conductive substrate, and is opposite For the second permanent magnet. The electromagnetic coil is adjacent to the first permanent magnet ring, and the current introduced by the electromagnetic coil changes periodically to change the position of the plasma mass to bombard the target; a cooling copper bottom plate is disposed on the second permanent magnet ring, the first permanent magnet a space enclosed by the ring and between the enclosed electromagnetic coil and the target; and a target disposed on the cooled copper base plate. The magnetron sputtering cathode according to claim 1, wherein the magnetic conductive substrate has a unit step shape, the unit step shape has a relatively high platform in the middle portion, and the closed second permanent The magnet ring is seated on the center line of the platform to support the cooling copper base plate, and a cooling water path is disposed below the platform portion of the magnetic conductive substrate. The magnetron sputtering cathode according to claim 1, wherein the magnetic conductive substrate further comprises at least one supporting column, the height of the supporting column being substantially equal to or slightly higher than the height of the electromagnetic coil, so that the cooling copper The bottom plate is supported by the support column. The magnetron sputtering cathode of claim 1, wherein the electromagnetic coil ranges from a target outer edge to a distance of 2/3 from the target. The magnetron sputtering cathode according to claim 1, wherein the electromagnetic coil is in the range The target midline is between 2/3 of the target width. A magnetron sputtering cathode, the magnetron sputtering cathode, comprising: at least: a magnetic conductive substrate, the magnetic conductive substrate is a unit step shape, the unit step shape has a relatively high platform in the middle portion; a permanent magnet ring seated on the outer ring of the magnetically permeable substrate; a second permanent magnet ring arranged in a closed arrangement, on the center line of the platform of the magnetically permeable substrate, the second permanent magnet and the first permanent magnet The N pole is opposite to the target surface; the closed electromagnetic coil is disposed on the magnetic conductive substrate and relative to the second permanent magnet. The electromagnetic coil is adjacent to the first permanent magnet ring, and the current introduced by the electromagnetic coil changes periodically to change the position of the plasma mass to bombard the target; a cooling copper bottom plate is disposed on the second permanent magnet ring, the first permanent magnet a space enclosed by the ring and between the enclosed electromagnetic coil and the target; and a target disposed on the cooled copper base plate. The magnetron sputtering cathode of claim 6, wherein the electromagnetic coil ranges from a target outer edge to a distance of 2/3 from the target. The magnetron sputtering cathode of claim 6, wherein the electromagnetic coil range is between the target centerline and 2/3 of the target width.