KR20180019027A - Metal deposition method on a substrate having nano-scaled holes - Google Patents

Abstract

The present invention relates to a metal deposition method for a substrate having fine holes sized from sub-micrometer to several hundred micrometers. The metal deposition method comprises: (a) a step of depositing metal on the upper surface of the substrate and fine holes by primarily sputtering a metal target by applying power to a sputter in a sputtering chamber; and (b) a step of applying an electrical bias to the substrate, generating low-density plasma by the applied bias, and secondarily sputtering the substrate with the low-density plasma. The metal material non-uniformly deposited on inner walls of the fine holes of the substrate by the primary sputtering in step (a) is uniformly applied to the inner walls of the fine holes of the substrate by the secondary sputtering in step (b). It is desired to apply an electric bias to the substrate by using a high-power impulse magnetron sputter generator in step (b).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a metal deposition method for depositing metal on a substrate having fine holes,

The present invention relates to a metal deposition method of a substrate having fine holes, and more particularly, to a method of depositing a metal layer on the inner wall of a microhole in a substrate having fine holes such as through holes, via holes or trenches of sub- And more particularly, to a metal deposition method capable of uniformly forming a metal film.

With the development of the information and communications industry, there is a growing demand for simpler and shorter terminals and related electronic components. In particular, in the field of printed circuit boards and packaging based on organic materials, build-up substrate technology, embedded performance and passive device technology, and micro-via technology have been actively studied and commercialized for 3D highly integrated packaging.

BACKGROUND ART Printed circuit boards (PCBs), also called PWBs, are formed by pressing a copper foil on one side or both sides of an insulating plate such as a phenol resin or an epoxy resin, ), And unnecessary portions are corroded to remove the copper foil to form a circuit. Holes are formed in the printed circuit board through holes for connecting the leads of the components or wiring between the upper surface and the lower surface, and the upper and lower surfaces are coated with PSR (Photo Solder Resist) ink The printed circuit board is completed.

In the process of manufacturing a multilayer printed circuit board, an inner via hole (IVH), a blind via hole (BVH), or a through hole (through hole) is formed in order to electrically connect the circuit pattern of each layer and the electronic device. : PTH) are formed. A via hole is formed in a substrate by using a drill to form a via hole on a surface of a substrate and an inner peripheral surface of a via hole and then filling a via hole in the via hole to form a via hole .

As described above, the via hole in the printed circuit board can be used as a conductor for depositing a metal such as copper on the inner wall of the via hole, filling the inside of the hole with electroplating, and connecting the wafer and the printed circuit board. Particularly, in the case of a wafer, a 3D semiconductor can be formed through the via hole connection, so that integration of the semiconductor can be achieved.

A conventional technique for forming a via hole in a printed circuit board is as follows.

Korean Unexamined Patent Application Publication No. 2002-0022477 discloses a method of forming a photographic developing type insulating resin layer on an upper surface and / or a lower surface of a center substrate and forming a predetermined via hole in the insulating resin layer, A method of manufacturing a build-up multilayer printed circuit board using a physical vapor deposition method, wherein a metal conductor layer is formed by a vapor deposition method.

In recent years, in order to achieve high integration of a semiconductor, a line width of a printed circuit board is reduced. As a result, the size of the via hole is reduced, and the aspect ratio of the hole depth to the hole becomes larger.

In the case of a printed circuit board having a large aspect ratio of a via hole, it is difficult to uniformly deposit on the inner wall of the via hole. As in the prior art, the technique of surface-treating the inner wall of the via hole and forming the metal conductor layer by the physical vapor deposition (PVD) method has a drawback in that since the metal atom flight is linear as compared with the case using the chemical vacuum deposition method (CVD) It is difficult to uniformly deposit the atoms on the inner wall of the via hole.

In recent years, the sizes of via holes and through holes passing through both sides of the substrate have been becoming finer to submicrometer to several hundred micrometers. As a result, the through hole or the like becomes finer and the deposition inside the hole becomes impossible. Therefore, a method using a vacuum deposition method is proposed as a unique method. According to such a situation, when a metal material is deposited using a physical vapor deposition (PVD) method such as sputtering on a substrate having a three-dimensional structure in which fine holes are formed, there arises a problem in step coverage due to the orientation of the deposition material . 1 is a cross-sectional view of a substrate when a metal vapor deposition film 104 is formed by metal vapor deposition in a substrate 100 having a fine hole 102 using a conventional PVD method. As shown in FIG. 1, a large amount of metal material is deposited on the surface or the upper region of the via hole or the through hole, and the metal material is hardly deposited on the lower portion of the via hole or the through hole, and the metal thin film is not uniformly formed.

Korean Patent Publication No. 2002-0022477 Korean Patent Publication No. 2014-0086928 Korean Patent Laid-Open Publication No. 2015-0140279

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems described above and to provide a method of forming a metal thin film uniformly on an inner wall of a microhole in a substrate having a microhole, such as a via hole, a through hole or a trench, And to provide a metal deposition method.

According to a first aspect of the present invention, there is provided a method of depositing a metal on a substrate having a sub-micrometer to several hundreds of micrometers in size, comprising the steps of: (a) applying power to a sputtering chamber in a sputtering chamber; Depositing a metal on the upper surface and the fine holes of the substrate by first sputtering the metal target; And (b) applying an electrical bias to the substrate, generating a low-density plasma by the applied bias, and secondarily sputtering the substrate with the low-density plasma, wherein the step (a) The metal material that is not uniformly deposited on the inner wall of the fine holes of the substrate by the sputtering is uniformly applied to the inner wall of the fine holes of the substrate by the second sputtering in the step (b).

In the metal deposition method according to the first aspect, it is preferable to apply an electrical bias to the substrate using the high-power impulse magnetron sputtering generator in the step (b).

In the metal deposition method according to the first aspect, in the step (a), a high power impulse magnetron sputtering generator may be used as the power source of the sputter, an arc source may be used, or a DC, RF And a pulse DC generator may be selected and used.

According to a second aspect of the present invention, there is provided a metal deposition method for a substrate having a sub-micrometer to several hundreds of micrometers in size, the method comprising: (a) first sputtering a first metal target to form an upper surface of the substrate, Depositing a first metal on the first metal; (b) disposing an insulating material over the second metal target and disposing a lower surface of the substrate over the insulating material; And (c) depositing a second metal on the inner wall of the fine holes of the substrate by irradiating an ion beam and second sputtering the second metal target, thereby depositing metal uniformly on the inner wall of the fine holes.

In the metal deposition method according to the second aspect of the present invention, it is preferable that the first metal target and the second metal target are made of the same metal material, and the same metal material is uniformly deposited on the inner wall of the fine hole.

In the metal deposition method according to the second aspect of the present invention, it is preferable that in the step (c), electrons are supplied to the surface of the substrate using a neutralization apparatus to neutralize the cations accumulated on the surface of the substrate.

In the metal deposition method according to the first embodiment of the present invention, a substrate having fine holes with a submicrometer to several hundreds of micrometers in size is first sputtered, and an electrical bias is applied to the substrate using a HiPIMS generator to perform secondary sputtering , The metal thin film can be uniformly formed on the entire inner wall of the fine holes of the substrate.

The metal deposition method according to the second embodiment of the present invention is a method of sputtering a substrate having fine holes with a submicrometer to several hundreds of micrometers in size, placing a metal target on the lower surface of the substrate, By sputtering, the metal thin film can be uniformly formed on the entire inner wall of the fine holes of the substrate.

FIG. 1 is a cross-sectional view of a substrate when metal deposition is performed on a substrate having fine holes using a conventional PVD method. FIG.
2 is a schematic view illustrating a method of depositing a metal on a substrate having a fine hole according to a first embodiment of the present invention.
3 is a schematic diagram showing a state in which a resistance of a substrate is measured in order to grasp the performance of a metal deposition method according to the present invention.
4 is a schematic diagram showing a metal deposition method in a substrate having a fine hole according to a second embodiment of the present invention.
FIG. 5 is a schematic view showing a process of sputtering a substrate when an ion beam is irradiated to a substrate on which a mask is formed, and the ion beam hits a region without a mask.
6 is a schematic diagram showing a process of neutralizing positive charges on a surface of a substrate using a neutralization apparatus in the metal deposition method according to the second embodiment of the present invention.

A metal deposition method according to the present invention is a method of depositing a metal on a substrate having a minute hole such as a sub-micrometer to a few hundred micrometer size through a fine hole such as a trench or the like using a sputtering method, Type power source is applied and re-sputtering is performed so that the non-uniformly deposited metal in the pattern of the fine holes can be uniformly applied to the inner wall of the fine holes as a whole.

Hereinafter, a method of uniformly depositing a metal on a substrate having fine holes such as through holes or trenches of submicrometer to several hundred micrometers in size according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. As used herein, the term " hole " refers to a term including a via-hole, a through-hole, a trench, etc. having a submicrometer to a radius of several hundreds of micrometers do.

≪ Embodiment 1 >

2 is a schematic view illustrating a method of depositing a metal on a substrate having a fine hole according to a first embodiment of the present invention.

Referring to FIG. 2, a metal deposition method of a substrate having a fine hole according to a first embodiment of the present invention includes: (a) first sputtering a metal target 206 in a sputtering chamber 200 to form a fine hole 102 Depositing a metal (104) on a surface of the substrate (100) having a plurality of holes and an inner wall of the fine holes; And (b) applying an electrical bias to the substrate 100, generating a low-density plasma by the applied bias, and re-sputtering the substrate with the low-density plasma. The metal material deposited in the fine holes of the substrate by the primary sputtering in the step (a) can be uniformly applied to the inner wall of the fine holes as a whole by the secondary sputtering in the step (b). Here, steps (a) and (b) may be performed sequentially or simultaneously.

In step (b), it is preferable to apply an electrical bias to the substrate using the high power impulse magnetron sputtering ('HiPIMS') generator 202. A high power impulse magnetron sputter (hereinafter, referred to as 'HiPIMS') is a power having a high output pattern in a pulse shape, and can lower an electric charge phenomenon as compared with a general DC power. The ionization rate of the generated plasma can be increased. In addition, the HiPIMS has an advantage in that the power intensity applied to the substrate to be biased can be adjusted by adjusting the output on / off ratio within the same time as the general DC power.

Thus, by applying an electrical bias to the substrate, a low density plasma is generated around the substrate by the applied bias, and a weak ion bombardment is caused by the low density plasma. As a result, a re-sputtering ). By the secondary sputtering, the metal materials that are deposited on the fine hole pattern uniformly are uniformly applied, so that the metal deposition film can be uniformly formed to the inner wall of the fine holes of the substrate.

When the material of the substrate is a conductor, DC (direct current) may be used as the bias power applied to the substrate. However, when the substrate is made of an insulator or a semiconductor, DC can not be used as a bias power applied to the substrate, and an RF generator or a pulse generator can be used. RF generator is advantageous because it has high ionization rate and can be used in non-conductor and semiconductor substrate. However, it has a high price of generator and a matching network unit must be additionally installed. have. In addition, when using a pulse generator, it is possible to use it in a substrate having an electrical property of an insulator and a semiconductor. However, since the ionization rate is lower than that of the RF generator, the plasma density is low, There is a disadvantage that there is no effect of changing the thin film characteristics by a low plasma density.

On the contrary, when the HiPIMS generator is used, the ionization rate is higher than that of the DC generator and the pulse DC generator, so that a high plasma density can be formed and the substrate can be used not only for a substrate having electrical characteristics of an insulator and a semiconductor, It has the advantage of relatively lower price than the RF generator.

In step (a), a power source 204 for generating plasma in the sputtering chamber 200 may be a HiPIMS generator, an arc source, or a DC, RF, or Pulse DC generator. have.

Through the above-described process, a metal thin film can be formed on the substrate by depositing a metal material on the surface of the substrate and the inner wall of the fine holes through the application of bias to the substrate and the power source of the sputter.

Table 1 shows the resistance of both surfaces of the substrate in order to understand the characteristics of the metal thin film formed on the substrate having the fine holes by the metal deposition method according to the present invention. 3 is a schematic diagram showing a state in which a resistance of a substrate is measured in order to grasp the performance of a metal deposition method according to the present invention.

(1) when only ARC power is applied by sputtering, (2) when ARC power is applied by sputtering and when HiPIMS bias is applied to the substrate, (3) DC power is applied by sputtering, and HiPIMS (5) When DC power is applied by a sputter and RF bias is applied to the substrate. (6) When the bias voltage is applied to the substrate by HiPIMS As a result of testing the performance of the metal thin film of the substrates formed by applying the power and applying the RF bias to the substrate, it is found that when the HiPIMS bias is applied to the substrate, the conductivity is excellent. It can be seen that the RF bias is excellent in the conductivity even when the RF bias is applied to the substrate. However, since the RF bias is expensive and the matching network unit must be installed separately, it is difficult to use the RF bias in actual field.

≪ Embodiment 2 >

Hereinafter, a method of depositing a metal on a substrate having fine holes according to a second embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a schematic diagram showing a metal deposition method in a substrate having a fine hole according to a second embodiment of the present invention. Referring to FIG. 4, a metal deposition method according to a second embodiment of the present invention includes: (a) first sputtering a first metal target to deposit a first metal on an upper surface of the substrate and an inner wall of the fine holes; (b) disposing an insulating material over the second metal target and disposing a lower surface of the substrate over the insulating material; (c) depositing a second metal on the inner wall of the fine hole of the substrate by irradiating an ion beam and second sputtering the second metal target, thereby depositing metal uniformly on the inner wall of the fine hole do. Here, the primary sputtering in the step (a) and the secondary sputtering in the step (c) may be performed sequentially or simultaneously in the sputtering chamber. 4 (a) is a schematic diagram showing the step (a), and FIG. 4 (b) is a schematic diagram showing steps (b) and (c).

Preferably, the first metal target and the second metal target are made of the same metal material, and the same metal material is uniformly deposited on the inner walls of the fine holes.

The primary sputtering process in the step (a) sputtering a metal such as copper using a generally known sputtering method in a sputtering chamber. In this case, the upper surface of the substrate 300 and the inner surface of the fine holes 302 The metal deposition layer 304 is formed nonuniformly as the metal particles are deposited only on the upper end of the fine holes and the metal particles are relatively less deposited on the lower end portion of the fine holes.

In the secondary sputtering process of the step (c), the second metal target 306 disposed on the lower surface of the substrate metallized by the first sputtering through the insulating material 308 is sputtered by irradiating the ion beam , And the second metal material is deposited on the lower end of the fine holes of the substrate. As described above, the metal vapor deposition film 304 can be uniformly formed on the inner walls of the fine holes of the substrate by the primary and secondary sputtering processes.

5 is a schematic diagram showing a process of sputtering a substrate when an ion beam is irradiated to a substrate 50 on which a mask 52 is formed, in which an ion beam hits an area without a mask. 5, when an ion beam is irradiated using an ion beam source under an appropriate vacuum with an inert gas such as argon in the substrate on which the mask is formed, the ion beam hits the maskless region, and as a result, Is sputtered. With this principle, in the present invention, the substrate on which the fine holes are formed serves as a mask, thereby shielding the ion beam.

Therefore, when the second metal target such as the copper target is disposed on the lower surface of the substrate and the ion beam is irradiated on the lower surface of the substrate as in the second embodiment, the ion beam passes through the fine holes and then charges the second metal target, The target is sputtered so that the second metal particles are deposited on the lower end of the fine holes. Accordingly, in the step (a), the metal deposition layer formed asymmetrically on the upper end of the fine hole is formed as a uniform metal deposition layer.

The step (c) may be performed by supplying a power source 310 to the second metal target 306. According to this embodiment, in order to uniformly deposit the metal on the inner wall of the fine holes formed in the substrate, the energy of the ion beam must be increased. However, if the energy of the ion beam is increased, the surface of the substrate is damaged by the high energy ion beam do. Therefore, it is desirable to relatively increase the energy of the incident ion beam by applying a power source such as DC having the opposite polarity to the charge of the ion beam to the second metal target while keeping the energy of the ion beam constant. The power source 310 connected to the second metal target 306 may be a DC generator or a pulse generator, or a HiPIMS generator may be used.

The insulating material 308 disposed between the lower surface of the substrate and the second metal target in step (b) may be an insulating tape, an insulating ceramic plate, or the like. It is preferable that power is not directly applied to the substrate even if the power source is connected to the second metal target by arranging it between the metal targets so as to prevent the substrate from being damaged.

The secondary sputtering in the step (c) is preferably performed under a controlled vacuum of 1 × 10 ^-4 to 3 × 10 ^-3 torr.

When the ion beam is irradiated outside the vacuum degree range, it collides with a gas such as argon present in the vacuum, so that the ions may lose the straight flight and scatter to collide with the second metal target.

On the other hand, in the metal vapor deposition method according to the second embodiment of the present invention, after the neutralization device is disposed on the front surface of the ion beam source, secondary sputtering is performed on the substrate to inject electrons into the space of the ion beam through the neutralization device Thereby neutralizing the positive charge on the surface of the substrate. 6 is a schematic diagram showing a process of neutralizing the positive charge on the surface of the substrate using the neutralization apparatus 60 in the metal deposition method according to the second embodiment of the present invention. Referring to FIG. 6, in the secondary sputtering process, the ion beam is positively charged and is irradiated onto the surface of the substrate to cause positive charge accumulation on the surface of the substrate. As a result, damage to the surface of the substrate is caused, It is difficult to straighten the ion beam in the hole. Therefore, it is necessary to neutralize the positive charges accumulated on the surface of the substrate by using a neutralization apparatus in the ion beam irradiation process.

In the metal deposition method according to the second embodiment of the present invention, it is preferable that the ion beam source use an ion beam source configured to extract only ions from the plasma and fly straight, but in some cases, a plasma source Can be used.

By the above-described method, it is possible to uniformly form the metal vapor deposition film on the inner wall of the nano-sized fine holes of the substrate.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various changes and modifications may be made without departing from the spirit and scope of the invention. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

The metal deposition method according to the present invention can be widely used in a semiconductor process for plating a substrate having a fine hole such as a through hole, a via hole, a trench or the like with a submicrometer to a few hundred micrometer size or depositing a metal.

100, 300: substrate
102, 302: fine holes
104, 304: metal deposition film
206: metal target
200: Sputtering chamber
202: HiPIMS generator
60: Neutralizer

Claims (9)

A method of depositing metal on a substrate having fine holes of submicrometer to several hundred micrometers in size,
(a) depositing a metal on the upper surface and the fine holes of the substrate by first sputtering the metal target by applying power to the sputter in the sputtering chamber; And
(b) applying an electrical bias to the substrate, generating a low-density plasma by the applied bias, and secondary sputtering the substrate with the low-density plasma;
Wherein the metal material deposited on the inner wall of the fine holes of the substrate by the primary sputtering in the step (a) is uniformly coated on the inner wall of the fine holes of the substrate by the secondary sputtering in the step (b) Wherein the substrate is a metal film. The method of claim 1, wherein in step (b), an electrical bias is applied to the substrate using the high-power impulse magnetron sputter generator. . The method of claim 1, wherein the metal deposition method is applicable to a substrate of a non-conductor, a semiconductor, and a conductor. The method as claimed in claim 1, wherein in the step (a), a high power impulse magnetron sputtering generator, an arc source, or a DC, RF, or Pulse DC generator is used as a power source of the sputtering Wherein the metal layer is formed on the substrate. A method of depositing metal on a substrate having fine holes of submicrometer to several hundred micrometers in size,
(a) depositing a first metal on an upper surface of the substrate and an inner wall of the microhole by sputtering a first metal target;
(b) disposing an insulating material over the second metal target and disposing a lower surface of the substrate over the insulating material;
(c) depositing a second metal on the inner walls of the fine holes of the substrate by irradiating an ion beam to sputter the second metal target;
Wherein the metal is uniformly deposited on the inner wall of the fine hole. The method of claim 5, wherein the first metal target and the second metal target are made of the same metal material, and the same metal material is uniformly deposited on the inner walls of the fine holes. . [6] The method of claim 5, wherein the step (a) and the step (c) are performed simultaneously or sequentially. 6. The method of claim 5, wherein step (c) is performed by supplying power to the second metal target. [6] The method of claim 5, wherein the step (c) comprises neutralizing the cations accumulated on the surface of the substrate by supplying electrons using a neutralization apparatus.

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