JP2000040880A - Apparatus and method for removing smear from multilayer substrate - Google Patents

Abstract

(57) [Problem] To provide a smear removing apparatus and a smear removing method for a multi-layer substrate capable of efficiently performing good smear removal. SOLUTION: In a smear removing apparatus for removing smear remaining at the bottom of an inner via hole of a multilayer substrate by plasma processing, a lower electrode 13 for mounting the multilayer substrate 1 on an upper surface exposed in a vacuum chamber 12, and a lower electrode 13 An upper electrode 17 disposed in the vacuum chamber in parallel to and grounded, a high-frequency power supply 16 for applying a high-frequency voltage to the lower electrode 12, and a vacuum exhaust section 14 and a plasma generating chamber in the vacuum chamber 12. A gas supply unit 15 for supplying gas;
A heat radiating plate 19 was attached and exposed to the outside to form a heat radiating portion, and a blower 21 was further provided. Thereby, the multilayer substrate can be cooled during the plasma processing, and only the smear can be efficiently removed without burning the multilayer substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smear removing apparatus and a smear removing method for removing smear remaining in an inner via hole of a multilayer substrate.

[0002]

2. Description of the Related Art A multi-layer substrate used for high-density mounting of electronic components is obtained by alternately laminating a plurality of circuit patterns with an insulating resin layer interposed therebetween. There is an advantage that a high-density circuit can be formed in the area. In order to form the wiring circuit three-dimensionally, it is necessary to conduct a predetermined portion between the respective layers of the conductor layer forming the circuit pattern. For this purpose, an inner via hole is formed in the insulating resin layer. According to this method, an inner via hole is formed at a predetermined position of an insulating resin layer, and a conductor such as copper is plated on the surface of the insulating resin layer to form a new conductor layer. The conduction is provided between the underlying conductor layer and the plating layer on the inner surface of the inner via hole.

[0003] As a method of forming the inner via hole,
Generally, laser processing and photolithography (photoengraving technology) are used. In the laser processing, a predetermined position of the insulating resin layer is irradiated with a laser, and the insulating resin in the irradiation range is evaporated and removed by the laser. At this time, it is difficult to completely remove the resin on the surface of the conductor layer, and smears made of resin having a minute thickness of 1 μm or less remain on the surface of the conductor layer. In the case of photolithography, a part to be an inner via hole is finally removed by etching. However, it is difficult to completely remove the resin on the surface of the conductor layer and the organic substances attached in the manufacturing process, and similarly, it remains as smear. If plating for forming a new conductor layer is performed with the smear remaining, problems such as poor plating and poor conduction are likely to occur. Therefore, after the formation of the via hole, prior to the plating step, the smear on the surface of the conductor layer in the inner via hole is removed by a method such as plasma treatment or wet treatment.

[0004]

However, conventionally, when smear is removed by using plasma processing, there are the following problems. Smear removal by plasma processing is to oxidize and burn smear, which is organic matter in the inner via hole, by oxygen gas plasma.
At the same time, the effect of the plasma processing extends to the multilayer substrate itself. Therefore, in the smear removing process, it is necessary to set plasma processing conditions that are sufficient to remove smear in the inner via hole and that do not burn out the multilayer substrate body. However, the conventional smear removing method using plasma processing has a problem that it is difficult to find such plasma processing conditions, and it is difficult to efficiently perform good smear removal.

Accordingly, an object of the present invention is to provide an apparatus and a method for removing smear of a multilayer substrate, which can efficiently remove good smear.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for removing smear of a multilayer substrate, which removes smear remaining at the bottom of an inner via hole formed in the multilayer substrate by plasma processing. A chamber, a top surface exposed in the vacuum chamber is a mounting portion on which the multilayer substrate is mounted, and a bottom surface exposed outside the vacuum chamber has a lower electrode forming a heat radiating portion, and a lower electrode parallel to the upper surface of the lower electrode. An upper electrode disposed in the vacuum chamber opposite to the ground electrode, a high-frequency power supply for applying a high-frequency voltage to the lower electrode, a vacuum exhaust unit for evacuating the vacuum chamber, and A gas supply unit for supplying a gas for plasma generation.

According to a second aspect of the present invention, there is provided a smear removing apparatus according to the first aspect, further comprising an air cooling means for forcibly air cooling the radiator.

A smear removing apparatus according to a third aspect is the smear removing apparatus according to the first or second aspect, further comprising pressing means for pressing the multilayer substrate against the upper surface of the lower electrode.

An apparatus for removing smear of a multilayer substrate, which removes smear remaining at the bottom of an inner via hole formed in the multilayer substrate by plasma processing, comprising: a vacuum chamber; and an upper surface exposed in the vacuum chamber. A lower electrode which is a mounting portion on which the multilayer substrate is mounted, cooling means for forcibly cooling the lower electrode, and a grounding means which is disposed in the vacuum chamber so as to face the upper surface of the lower electrode in parallel and is grounded. An upper electrode, a high-frequency power supply for applying a high-frequency voltage to the lower electrode, a vacuum exhaust unit for evacuating the vacuum chamber, and a gas supply unit for supplying a gas for plasma generation into the vacuum chamber. Was.

A smear removing apparatus according to a fifth aspect is the smear removing apparatus according to the fourth aspect, further comprising a pressing means for pressing the multilayer substrate against the upper surface of the lower electrode to make contact therewith.

According to a sixth aspect of the present invention, there is provided a method of removing smear of a multilayer substrate, wherein the smear remaining at the bottom of the inner via hole formed in the multilayer substrate is removed by plasma processing. After mounting the multilayer substrate on the mounting portion also serving as the lower electrode, evacuating the vacuum chamber, and then supplying a gas for plasma generation into the vacuum chamber, the substrate is opposed to the upper surface of the lower electrode in parallel. A plasma is generated in the vacuum chamber by applying a high-frequency voltage to an upper electrode disposed in the vacuum chamber, and the multilayer substrate is cooled when the smear is removed by the plasma.

The method for removing smear according to claim 7 is the method for removing smear according to claim 6, wherein the method for cooling the multilayer substrate includes bringing the multilayer substrate into contact with the lower electrode provided with cooling means. And conducting the heat of the multilayer substrate to the lower electrode.

[0013] In the multilayer substrate according to the present invention, a step of forming an insulating resin layer covering the circuit pattern on a surface of the substrate on which the circuit pattern is formed; a step of forming an inner via hole in the insulating resin layer; It was manufactured by a method including a step of removing smear remaining in the inner via hole by plasma while cooling the substrate, and a step of forming a conductor layer in the inner via hole from which the smear was removed.

According to the invention, when removing the smear remaining in the inner via hole by the plasma treatment, the multilayer substrate is cooled to efficiently remove only the smear without burning the multilayer substrate. can do.

[0015]

(Embodiment 1) FIG. 1 is a cross-sectional view of an apparatus for removing smear from a multilayer substrate according to Embodiment 1 of the present invention, and FIGS. 2 (a), (b) and (c) show the same multilayer. Cross section of substrate, FIG.
Is an enlarged sectional view of the multilayer substrate, and FIGS. 4 (a), (b),
(C) is a sectional view of the multilayer substrate.

First, the structure of a device for removing smear from a multilayer substrate will be described with reference to FIG. In FIG. 1, the smear removing device 11 includes a vacuum chamber 12. An opening 12 a is provided on the lower surface of the vacuum chamber 12, and the lower electrode 1 is formed in the opening 12 a from the lower surface of the vacuum chamber 12.
3 is inserted. The lower electrode 13 is fixed to the lower surface of the vacuum chamber 12 via an insulating member 18. The upper surface of the lower electrode 13 is exposed in the vacuum chamber 12, and the multilayer substrate 1 is mounted on the upper surface. Therefore, the upper surface of the lower electrode 13 is a mounting portion. The lower surface of the lower electrode 13 is exposed to the outside of the vacuum chamber 12 to form a radiator for dissipating the heat of the lower electrode to the outside, and a radiator plate 19 having a number of fins 19a is attached. Below the radiator plate 19, a blower 21 as an air cooling means is installed, and by blowing air to the fins 19a,
The heat of the lower electrode 13 is dissipated through the fins 19a and cooled.

An upper electrode 17 is provided in the vacuum chamber 12 so as to be opposed to the upper surface of the lower electrode 13 in parallel and grounded to a grounding section 20. A high frequency power supply 16 is connected to the lower electrode 13, and a high frequency voltage is applied between the lower electrode 13 and the upper electrode 17 by driving the high frequency power supply 16. A vacuum exhaust unit 14 and a gas supply unit 15 are connected to the vacuum chamber 12. The vacuum exhaust unit 14 exhausts the inside of the vacuum chamber 12 to reduce the pressure. The gas supply unit 15 supplies a gas for generating oxygen plasma, such as oxygen gas or a mixed gas of oxygen gas and argon gas, into the vacuum chamber 12. Although the first embodiment shows an example in which the lower electrode 13 is manufactured as a single body,
Those divided into several layers in the vertical direction may be used in combination. Further, the vacuum chamber 12 itself may be grounded so that the vacuum chamber 12 also serves as the upper electrode.

This smear removing apparatus is configured as described above. The process of manufacturing a multilayer substrate and the removal of smear performed in this process will be described below with reference to the drawings. In FIG. 2A, circuit patterns 2 are formed on both upper and lower surfaces of a resin substrate 1. The circuit pattern 2 is made of a copper film as a conductor layer, and is formed by forming a copper film on both surfaces of the substrate 1 by copper plating and then removing portions other than the circuit pattern portion by patterning. After this,
As shown in FIG. 2B, an insulating resin layer 3 is formed on both surfaces of the substrate 1 so as to cover the circuit pattern 2. The insulating resin layer 3 is an insulating thermosetting resin such as an epoxy resin.
It is coated with a film thickness of about several tens to several hundreds of microns.

After that, an inner via hole is formed in the insulating resin layer 3. This inner via hole has a circuit pattern newly formed on the surface of the insulating resin layer 3,
This is for electrically connecting the existing circuit pattern 2 on the surface of the substrate 1 with the laser processing, as shown in FIG.
As shown in (1), they are provided corresponding to predetermined positions of the circuit pattern 2. At this time, as shown in FIG. 3, on the surface of the circuit pattern 2 in the inner via hole 4, a residue (smear) of the insulating resin remaining without being removed at the time of laser processing exists as a very thin resin film of about 1 μm. ing. The smear 3a needs to be removed because the smear 3a impairs the adhesion of the copper plating to the surface of the circuit pattern 2 in the copper plating in the next step.

Therefore, using the plasma processing apparatus 11,
The surface of the substrate 1 after the laser processing is subjected to plasma processing to remove smear on the surface of the circuit pattern 2 in the inner via hole 4. As shown in FIG. 1, a substrate 1 is placed on a lower electrode 13 provided at the bottom of a vacuum chamber 12 with the surface to be processed facing upward. After the vacuum chamber 12 is closed and sealed and the inside of the vacuum chamber 12 is evacuated by the vacuum exhaust unit 14, a gas for plasma generation such as oxygen or a mixed gas of argon and oxygen is supplied into the vacuum chamber 12 by the gas supply unit 15. I do. Then, by the high frequency power supply 16,
A high-frequency voltage is applied between the lower electrode 13 and the upper electrode 17 provided in the upper part of the vacuum chamber 12.

As a result, oxygen plasma is generated in the vacuum chamber 12 (see hatching in FIG. 1).
Particles such as oxygen ions and electrons collide with the surface of the substrate 1. Due to this ion bombardment, the surface layer of the insulating resin layer 3 which is an organic substance covering the surface of the substrate 1 is removed from the surface of the insulating resin layer 3 by being combined with oxygen ions to become water and carbon dioxide. At the same time, the smear 3a on the surface of the circuit pattern 2 in the inner via hole 4 is similarly removed.

At this time, by mounting the substrate 1 directly on the lower electrode 13, a self-bias is applied to the substrate 1, and oxygen ions incident on the substrate 1 are incident vertically from above. The ion bombardment promotes the above-described organic substance removal reaction. On the other hand, the inner surface of the inner via hole 4 is hardly affected by the ion bombardment, and as a result, the organic substance removing reaction is applied only in the vertical direction. Therefore, according to the plasma processing method described in the present embodiment, the diameter of the inner via hole 4 does not increase as in the conventional smear removing method, and the smear removing method is suitable for a case where minute holes are targeted. I have.

In the process of removing smear, the multilayer substrate 1
Is placed in contact with the upper surface of the lower electrode 13, heat given to the multilayer substrate 1 by the plasma processing is transmitted to the lower electrode 13 by heat conduction. here,
The lower electrode 13 is provided with a heat radiating plate 19 exposed to the outside of the vacuum chamber 12, and furthermore, is cooled by an air blower 21, so that heat is constantly radiated from the lower electrode 13 to the outside, and the lower electrode 13 is cooled to a predetermined temperature or lower. Is kept. Therefore, the temperature of the multilayer substrate 1 does not rise to a predetermined temperature or more, and the multilayer substrate 1 is not burned by the heat of the plasma processing in the smear removing process.

Next, as shown in FIG. 4A, a copper film 30 as a new conductor layer is formed on the insulating resin layer 3 of the substrate 1 from which smear has been removed by copper plating. At this time, the copper film 30 is exposed in the inner via hole 4.
Is formed at the same time in the inside of That is, the circuit pattern 2 exposed on the bottom surface of the inner via hole 4 is electrically connected to the newly formed copper film 30.
In addition, as a method of forming a conductor layer in the inner via hole 4, a method of supplying a solder paste or a conductive paste into the inner via hole 4 in addition to plating may be used. That is, the formation of the conductor layer in the inner via hole 4 and the formation of the conductor layer on the surface of the insulating resin layer 3 may be performed in different steps. Next, as shown in FIG. 4B, patterning is performed on the copper film 30, and a second-layer circuit pattern 30 a electrically connected to the circuit pattern 2 is formed on the surface of the insulating resin layer 3.

Thereafter, as shown in FIG. 4C, the insulating resin layer 31 is formed again to cover the second-layer circuit pattern 30a, and then the inner via hole 4 shown in FIG. 2C is formed again. Is performed. By repeating the above-described steps a predetermined number of times according to the number of layers of the multilayer substrate to be manufactured, a multilayer substrate is manufactured.

(Embodiment 2) FIG. 5 is a sectional view of a smear removing apparatus according to Embodiment 2 of the present invention. The smear removing device 11 'shown in FIG. 5 is obtained by replacing the lower electrode 13 of the smear removing device 11 in the first embodiment with a lower electrode 23 having a water jacket as a cooling means. In FIG. 5, the lower electrode 23 is provided with a cooling hole 24 forming a water jacket. Cooling hole 2
4 are connected to a cooling water supply unit 26 via a pipe 25. By driving the cooling water supply unit 26 to circulate the cooling water in the cooling holes 24, the lower electrode 23 can be efficiently cooled. Therefore, the multilayer placed on the upper surface of the lower electrode 23 in the smear removing process. The substrate 1 can be efficiently cooled to prevent burnout.

In the example shown in the second embodiment, the lower surface of the lower electrode 23 has a shape exposed to the outside of the vacuum chamber 12, but the lower electrode 23 is water-cooled, so that a heat radiating portion is unnecessary. Therefore, the lower electrode 23 is not limited to this shape, and may be entirely contained in the vacuum chamber 12.

(Embodiment 3) FIG. 6 is a sectional view of a smear removing apparatus according to Embodiment 3 of the present invention. In the smear removing device 31 shown in FIG. 6, the smear removing device 11 'in the second embodiment is provided with a pressing means for pressing the multilayer substrate 1 against the upper surface of the lower electrode. In FIG. 6, the lower electrode 33 is provided with a cooling hole 24 forming a water jacket, which is a cooling means, as in the second embodiment, and is connected to a cooling water supply unit 26. A suction groove 34 for vacuum suction is provided on the upper surface of the lower electrode 33, and a seal member 35 is provided outside the suction groove 34 in a circumferential shape in plan view. The suction groove 34 is connected to a second vacuum exhaust unit 38 via a suction hole 36 and a pipe 37.

When the second evacuating unit 38 is driven in a state where the multilayer substrate 1 is mounted on the lower electrode 33, the sealing member 35 is provided in the gap between the upper surface of the multilayer substrate 1 and the upper surface of the lower electrode 33.
Is evacuated through a suction groove 34. At this time, by setting the suction pressure of the second vacuum exhaust unit 38 for sucking the gap to be lower than the suction pressure of the first vacuum exhaust unit 14 for vacuum-disposing the inside of the vacuum chamber 12, the multilayer substrate 1 is pressed against the upper surface of the lower electrode 33 by the difference between the pressure in the chamber 12 and the pressure in the gap. That is, the suction groove 34, the sealing member 35, and the second evacuation unit 38 are pressing means for pressing the multilayer substrate 1 against the upper surface of the lower electrode 33.

When the multilayer substrate 1 is pressed against the upper surface of the lower electrode 33, the multilayer substrate 1 comes into contact with the lower electrode 33 with good adhesion. In this state, when the cooling water supply unit 26 is driven to cool the lower electrode 33, heat from the multilayer substrate 1 is transmitted to the lower substrate 33 well, and the multilayer substrate 1 is efficiently cooled. Thereby, burning of the multilayer substrate 1 in the smear removing process can be reliably prevented.

In the example shown in the third embodiment, an example is shown in which the lower electrode 33 is water-cooled by the cooling means as in the second embodiment, but as shown in the first embodiment (FIG. 1). Even in the case where the lower electrode 13 is air-cooled, the pressing means using the suction groove and the second vacuum exhaust unit shown in the third embodiment can be provided. The present invention can be applied not only to the case where the inner via hole is formed by laser processing but also to the case where the inner via hole is formed by photolithography.

[0032]

According to the present invention, when the smear remaining in the inner via hole is removed by plasma processing, the multilayer substrate is cooled, so that the heat generated by the plasma processing in the smear removing process is generated by the multilayer substrate. Thus, burning can be effectively prevented, and only the smear in the inner via hole can be efficiently and satisfactorily removed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an apparatus for removing smear from a multilayer substrate according to a first embodiment of the present invention.

FIG. 2A is a cross-sectional view of the multilayer substrate according to the first embodiment of the present invention. FIG. 2B is a cross-sectional view of the multilayer substrate according to the first embodiment of the present invention. Sectional view

FIG. 3 is an enlarged cross-sectional view of the multilayer substrate according to the first embodiment of the present invention.

4A is a cross-sectional view of the multilayer substrate according to the first embodiment of the present invention. FIG. 4B is a cross-sectional view of the multilayer substrate according to the first embodiment of the present invention. Sectional view

FIG. 5 is a sectional view of a smear removing apparatus according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a smear removing apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer board 2 Circuit pattern 3 Insulating resin layer 3a Smear 4 Inner via hole 11 Plasma processing device 12 Vacuum chamber 13,23,33 Lower electrode 14 Vacuum exhaust part 15 Gas supply part 16 High frequency power supply 17 Upper electrode 19 Heat sink 20 Heat sink 20 Ground Blower 26 Cooling water supply unit 38 Second evacuation unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoto Yoshida 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Tetsuhiro Iwai 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co. F term (reference) 5E346 AA06 AA12 AA15 AA43 BB01 DD03 DD22 DD32 EE33 EE34 FF03 FF07 FF18 FF19 GG01 GG15 GG16 GG17 GG19 GG22 HH33 HH40

Claims (8)

[Claims] An apparatus for removing smear of a multilayer substrate, which removes smear remaining at the bottom of an inner via hole formed in the multilayer substrate by plasma processing, comprising: a vacuum chamber;
The upper surface exposed in the vacuum chamber is a mounting portion on which the multilayer substrate is mounted, and the lower surface exposed outside the vacuum chamber is opposed to a lower electrode forming a heat radiating portion in parallel with the upper surface of the lower electrode. An upper electrode disposed in the vacuum chamber and grounded; a high-frequency power supply for applying a high-frequency voltage to the lower electrode; a vacuum exhaust unit for evacuating the vacuum chamber; And a gas supply unit for supplying the gas. 2. The apparatus according to claim 1, further comprising an air cooling means for forcibly cooling the heat radiating unit with air. 3. The apparatus for removing smear of a multilayer substrate according to claim 1, further comprising pressing means for pressing said multilayer substrate against an upper surface of said lower electrode to make contact therewith. 4. An apparatus for removing smear of a multilayer substrate, which removes smear remaining at the bottom of an inner via hole formed in the multilayer substrate by plasma processing, comprising: a vacuum chamber;
A lower electrode whose upper surface exposed in the vacuum chamber is a mounting portion on which the multilayer substrate is mounted; cooling means for forcibly cooling the lower electrode; An upper electrode disposed in the chamber and grounded, a high-frequency power supply that applies a high-frequency voltage to the lower electrode, and a vacuum exhaust unit that evacuates the vacuum chamber,
A gas supply unit for supplying a gas for plasma generation into the vacuum chamber. 5. The apparatus for removing smear of a multilayer substrate according to claim 4, further comprising pressing means for pressing said multilayer substrate against an upper surface of said lower electrode to make contact therewith. 6. A method for removing smear of a multilayer substrate, which removes smear remaining at the bottom of an inner via hole formed in the multilayer substrate by a plasma treatment, wherein the smear is removed from a mounting portion provided in a vacuum chamber and serving also as a lower electrode. After evacuating the inside of the vacuum chamber and supplying a gas for plasma generation into the vacuum chamber, the multi-layer substrate was placed in the vacuum chamber so as to face in parallel with the upper surface of the lower electrode. Plasma is generated in the vacuum chamber by applying a high-frequency voltage between the upper electrode and the upper electrode, and the multilayer substrate is cooled when the plasma is used to remove the smear. Method. 7. The method for cooling the multilayer substrate is a method in which heat of the multilayer substrate is conducted to the lower electrode by bringing the multilayer substrate into contact with the lower electrode provided with cooling means. The method for removing smear from a multilayer substrate according to claim 6. 8. The method according to claim 8, wherein the circuit pattern is formed on a surface of the substrate.
Forming an insulating resin layer covering the circuit pattern;
A step of forming an inner via hole in the insulating resin layer, a step of removing smear remaining in the inner via hole by plasma while cooling the substrate, and a step of forming a conductor layer in the inner via hole from which the smear has been removed; A multilayer substrate manufactured by a method comprising: