JP2003096554A - Metal film forming method for ceramic base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal film forming method for a ceramic base material in which a metal film can be formed on the nitride or carbide ceramic base material with excellent adhesivity. SOLUTION: The metal film is formed on the nitride or carbide ceramic base material 1 after performing the surface modification treatment by oxygen plasma. In this modification treatment, a holding electrode 3 to hold the ceramic base material 1 and a facing electrode 4 are disposed facing each other, the high frequency power is supplied preferably by a high frequency power source 5 to the holding electrode 3 in a state in which the atmospheric gas including gaseous oxygen is present. Alternatively, the high frequency power is supplied preferably to the holding electrode 3 and the facing electrode 4 by high frequency power sources independent from each other. Gaseous oxygen and gaseous argon are preferably contained in the atmospheric gas in a space between the holding electrode 3 and the facing electrode 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal film on the surface of a ceramic base material composed of nitride ceramics and carbide ceramics.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a circuit board or the like of an electronic device, a ceramic substrate is metallized to form a metal film such as a copper film on the surface, and a conductor circuit is formed on the metal film. It was being appreciated.

Examples of the ceramic base material used for manufacturing the ceramic circuit board include ceramics such as aluminum nitride sintered body and silicon carbide sintered body, or glass. As a metallizing method for forming a metal film on such a ceramic substrate,
Examples thereof include electroless plating method and physical vapor deposition method.

Among them, the physical vapor deposition method is a method of depositing copper on a ceramic substrate by a method such as argon sputtering to form a copper film, and a conductor circuit is formed without surface roughening. Compared with electroless plating, which cannot be done, a conductor circuit can be formed on an aluminum nitride base material or the like without roughening the surface, so that it has the advantage of excellent high frequency characteristics.

FIG. 13 schematically shows a step of forming a metal film by a physical vapor deposition method. A preparation chamber 7'for preheating the ceramic base material 1 and the ceramic base material 1 are provided. An RF plasma chamber 8'for performing a high-frequency plasma treatment such as an argon plasma treatment as a pretreatment, a sputtering chamber 9'for depositing a metal film on the plasma-treated ceramic substrate 1 by sputtering, and a metal film were formed. A take-out chamber 1 for taking out the ceramic base material 1.
It is composed of 0 '.

FIG. 14 shows an example of an RF plasma chamber 8'for performing an argon plasma treatment on the ceramic base material 1. A holding electrode 3'and a counter electrode 4'are provided in the chamber 11 '. , The holding electrode 3'is connected to a high frequency power source 5'through a matching circuit 12 ', and the counter electrode 4'is grounded through a chamber 11'. Inside the chamber 11 ', a plasma is introduced from a gas inlet 13'. The atmosphere gas for generation can be introduced. Then, the ceramic substrate 1 is held in contact with the holding electrode 3'and set in the chamber 11 ', and an atmospheric gas such as argon gas is introduced into the chamber 11' through the gas inlet 13 '. By supplying high frequency power to the holding electrode 3 ', plasma P', such as argon plasma, is generated by the gas discharge phenomenon between the holding electrode 3'and the counter electrode 4 '. When the plasma P ′ is generated in this way, the argon ions in the plasma P ′ act on the surface of the ceramic base material 1 to remove the contaminant 14 ′ on the surface of the ceramic base material 1 as shown in FIG. At the same time as cleaning, the chemical bond in the surface layer of the ceramic substrate 1 is cleaved to expose the dangling bond 16 '.

After the surface of the ceramic base material 1 has been modified in this way, a metal film is formed on the surface of the ceramic base material 1 by a vapor deposition method such as sputtering in the sputtering chamber 9. It is intended to improve the adhesiveness of the metal film to 1.

[0008]

However, in the conventional method of forming a metal film as described above, particularly when a metal film is formed on the surface of the ceramic substrate 1 made of a nitride or a carbide, a nitride film or a nitride film is formed. Since the adhesion between the carbide and the metal such as copper is weak, it is difficult to provide sufficient adhesion between the ceramic base material 1 and the metal film even if the above pretreatment with argon plasma is performed. It was a thing.

The present invention has been made in view of the above points, and a metal film for a ceramic base material capable of forming a metal film with good adhesion on a nitride-based or carbide-based ceramic base material is provided. It is intended to provide a forming method.

[0010]

According to a first aspect of the present invention, there is provided a method for forming a metal film on a ceramic substrate, wherein a nitride-based or carbide-based ceramic substrate 1 is subjected to surface modification treatment by oxygen plasma. A feature is that a metal film is formed later.

The invention of claim 2 is characterized in that, in claim 1, a metal film is formed by vapor deposition, sputtering or ion plating on the substrate which has been surface-modified by oxygen plasma. is there.

According to a third aspect of the present invention, in the first or second aspect, the holding electrode 3 holding the ceramic base material 1 and the counter electrode 4 are arranged to face each other, and the holding electrode 3 and the counter electrode 4 are arranged. The surface modification treatment is performed by supplying high frequency power from the high frequency power supply 5 to the holding electrode 3 in a state where an atmosphere gas containing oxygen gas is present therebetween.

The invention of claim 4 is characterized in that, in the surface modification treatment, high-frequency power is supplied to the holding electrode 3 and the counter electrode 4 by independent high-frequency power sources 5, respectively. Is.

Further, the invention of claim 5 is the method according to claim 3 or 4, wherein the atmosphere gas between the holding electrode 3 and the counter electrode 4 contains oxygen gas and argon gas during the surface modification treatment. It is a feature.

The invention of claim 6 is characterized in that, in the surface modification treatment, plasma treatment is first performed in an argon gas atmosphere, and then oxygen gas is introduced to subsequently perform plasma treatment. To do.

According to a seventh aspect of the present invention, in the sixth aspect, the holding electrode 3 and the counter electrode are arranged so that the total pressure of the atmospheric gas between the holding electrode 3 and the counter electrode 4 becomes constant during the surface modification treatment. 4, and argon gas and oxygen gas are supplied between them.

Further, the invention of claim 8 is the method according to any one of claims 1 to 7, wherein a metal oxide is formed on the surface of the ceramic substrate 1 which has been subjected to the surface modification treatment by reactive sputtering. It is characterized in that a metal film is formed by sputtering.

According to a ninth aspect of the present invention, in the eighth aspect, when the metal oxide is formed by the reactive sputtering, the oxygen gas concentration in the atmosphere is continuously decreased to form a layer made of the metal oxide. It is characterized by forming a composition gradient such that the content of the metal with respect to the metal oxide increases toward the surface layer side.

The invention of claim 10 relates to claims 1 to 9.
In any of the above, when a metal film is formed on the surface of the ceramic base material 1 which has been subjected to the surface modification treatment by sputtering, the ion beam 6 of argon is irradiated.

The invention of claim 11 relates to claims 1 to 7.
And in any one of claims 10 to 10, when forming a metal film by sputtering on the surface of the ceramic substrate 1 that has been subjected to the surface modification treatment, the ion beam 6 of oxygen is irradiated. is there.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

In the present invention, the ceramic base material 1 is made of a nitride ceramic such as aluminum nitride or a carbide ceramic such as silicon carbide.

An example of steps for forming a metal film on the ceramic substrate 1 is shown in FIG. Here, first, the ceramic base material 1 is introduced into the charging chamber 7 and preheated, and then the ceramic base material 1 is introduced into the RF plasma chamber 8 and subjected to surface modification treatment by oxygen gas plasma as pretreatment, and then, Plasma-treated ceramic substrate 1
Is introduced into the sputtering chamber 9 to form a metal film, and the ceramic substrate 1 having the metal film formed thereon is taken out from the extraction chamber 10.

As the metal film, a film made of an appropriate metal is formed, and particularly when it is formed as a conductor film (conductor circuit), a metal film made of copper, aluminum, nickel or the like may be formed. Preferably, when forming the resistor, it is preferable to form a metal film made of, for example, a nickel-chromium alloy.

FIG. 3 shows an example of the structure of the RF plasma chamber 8 for performing the surface modification treatment by oxygen gas plasma. In the illustrated example, the RF plasma chamber 8 is configured as a high frequency plasma processing apparatus, and performs surface modification processing by capacitively coupled plasma. Here, the chamber 11
A flat plate-shaped holding electrode 3 and a counter electrode 4 are arranged in parallel with each other so as to face each other. The holding electrode 3 is connected to a high frequency power source 5 via a matching circuit 12, and the holding electrode 3 holds the ceramic base material 1 on the side facing the counter electrode 4, while the counter electrode 4 is held. Is grounded through the chamber 11. Further, the chamber 11 is provided with a gas introduction port 13 so that an atmospheric gas for plasma generation can be introduced from the gas introduction port 13 into the chamber 11.

When the ceramic substrate 1 is subjected to the surface modification treatment, the holding electrode 3 holds the ceramic substrate 1 and sets it in the chamber 11, and the chamber 11 is evacuated by a vacuum pump. After decompressing the inside of the chamber 11 to, for example, about 10 ⁻⁴ Pa, the gas inlet 1
Oxygen gas is introduced into the chamber 11 from 3 as an atmospheric gas for plasma generation. Chamber 11 at this time
The gas pressure of the oxygen gas inside is set to about 10 Pa, for example.

In this state, by supplying high frequency power to the holding electrode 3 from the high frequency power source 5, the oxygen gas is ionized by the gas discharge phenomenon by the high frequency glow discharge between the holding electrode 3 and the counter electrode 4, and the plasma P is generated. Is generated.
The high-frequency power supply conditions at this time are set appropriately,
For example, the frequency is 13.56 MHz, the output is 200 W, and the processing time is 1 minute.

At this time, as shown in FIG.
Oxygen ions therein collide with the ceramic base material 1 and act on the surface of the ceramic base material 1 to perform cleaning for removing contaminants 14 on the surface of the ceramic base material 1. At this time, the contaminants 14 are also removed by the kinetic energy of the oxygen ions. However, when the organic contaminants 14 adhere to the surface of the ceramic substrate 1, the contaminants 14 are chemically removed. It can be removed by decomposing it into gas and vaporizing it as CO ₂ etc.
The removal effect of No. 4 is high. Further, due to the action of oxygen ions, metal-
The nitrogen bond or the metal-carbon bond is cleaved, and the oxygen ion in the plasma P is bonded to the metal atom to form the oxide layer 15.
Is formed. Furthermore, on the surface of the oxide layer 15,
The dangling bonds 16 mainly through oxygen in the form of "metal-oxygen-" are formed to activate the surface. When a metal film is formed on the surface of the ceramic substrate 1 that has been subjected to such surface modification treatment, the metal film and the oxide layer 1 are formed.
No. 5 is bonded through a metal-oxygen bond having a strong bonding force, and the adhesion of the metal film is improved as compared with the case where the metal film is directly formed on the surface of the nitride-based or carbide-based ceramics. In addition, since the surface of the oxide layer 15 is activated as described above when the metal film is formed, the adhesion of the metal film is further improved.

FIG. 4 shows another example of the RF plasma chamber 8 in which the surface modification treatment is performed, and the holding electrode 3 and the counter electrode 4 are arranged in the chamber 11 so as to face each other. The holding electrode 3 is connected to a high frequency power source 5 via a matching circuit 12, and the holding electrode 3 holds a plurality of ceramic base materials 1 on both sides. Further, the counter electrode 4 is disposed on one surface side and the other surface side of the holding electrode 3 so as to face the holding electrode 3, and each holding electrode 3 is connected to the chamber 11 and the chamber 11 is grounded. .

In this case as well, the surface modification treatment can be applied to the ceramic substrate 1 as shown in FIG. 3, but the ceramic substrate 1 is arranged on both sides of the holding electrode 3. The ceramic substrate 1 can be subjected to a surface modification treatment, and the treatment efficiency is improved as compared with the case where the counter electrode 4 is provided on one side of the holding electrode 3 as shown in FIG.

FIG. 5 shows another example of the RF plasma chamber 8 for performing the surface modification treatment, in which the holding electrode 3 and the counter electrode 4 are arranged in the chamber 11 so as to face each other. The holding electrode 3 is connected to a high-frequency power source 5 via a matching circuit 12, and the holding electrode 3 holds the ceramic base material 1 on the side facing the counter electrode 4. The counter electrode 4 is also connected to a high frequency power source 5 via a matching circuit 12, and the holding electrode 3 and the counter electrode 4 are connected to separate high frequency power sources 5 and 5, respectively. Further, the chamber 11 is provided with a gas introduction port 13 so that an atmospheric gas for plasma generation can be introduced from the gas introduction port 13 into the chamber 11.

Then, the ceramic substrate 1 is formed on the holding electrode 3.
And set in the chamber 11,
The inside of the chamber 11 is evacuated to, for example, 10 ⁻⁴ P inside the chamber 11.
After reducing the pressure to about a, oxygen gas is introduced into the chamber 11 through the gas inlet 13 as an atmospheric gas for plasma generation. The gas pressure of the oxygen gas in the chamber 11 at this time is set to about 10 Pa, for example.

In this state, by supplying high frequency power from the high frequency power source 5 to the holding electrode 3 and also supplying high frequency power from the other high frequency power source 5 to the counter electrode 4, a gap between the holding electrode 3 and the counter electrode 4 is obtained. Plasma P is generated by the gas discharge phenomenon due to the high frequency glow discharge in the above.

At this time, the high frequency power supplied to the counter electrode 4 mainly acts to generate plasma,
The high frequency power supplied to the holding electrode 3 acts as a bias. Oxygen ions are accelerated by this bias and collide with the ceramic base material 1 to clean the surface of the ceramic base material 1, form the oxide layer 15, and activate the surface of the oxide layer 15.

Further, as described above, the ceramic substrate 1
When the surface modification treatment is performed on the holding electrode 3 and the counter electrode 4, the holding electrode 3 and the counter electrode 4 are supplied with high frequency power, and the supplied high frequency power can be controlled separately. The density of the plasma P generated in the space can be adjusted by controlling the high frequency power supplied to the counter electrode 4, and the energy when the ions collide with the ceramic substrate 1 is supplied to the holding electrode 3. It can be adjusted by controlling the generated high frequency power to control the negative self-bias voltage applied to the ceramic base material 1, and the density of the generated plasma P and the collision of ions with the ceramic base material 1 at the time of collision. Energy can be controlled separately and independently.

In controlling the high frequency power supplied to the holding electrode 3 and the counter electrode 4 as described above, the high frequencies supplied to the holding electrode 3 and the counter electrode 4 are in phase with each other, and thus the high frequencies of the two are mutually matched. Of the counter electrode 4 so that the plasma P having an appropriate density is generated.
While controlling the high frequency power supplied to the ceramic substrate 1, a proper negative bias voltage is applied to the ceramic substrate 1 so that the ions in the plasma P collide with the ceramic substrate 1 with appropriate kinetic energy. That is, as shown in FIGS. 3 and 4, when the high frequency power is supplied only to the holding electrode 3, the density of the plasma P and the bias voltage are controlled by the same power source, so that they cannot be controlled independently of each other, which is optimum. Although it is difficult to obtain the conditions, if the high-frequency power supplied to the holding electrode 3 and the counter electrode 4 is independently controlled as described above, the density of the plasma P and the bias voltage can be independently controlled. Even if the density of the generated plasma P is increased, the collision energy of the ions with respect to the ceramic base material 1 can be appropriately maintained.

The conditions for supplying the high frequency power to the holding electrode 3 and the counter electrode 4 are appropriately set. For example, the conditions for supplying the high frequency power applied to the counter electrode 4 are a frequency of 200 MHz and an output of 500 W, while applying to the holding electrode 3. The high frequency power has a frequency lower than that of the counter electrode 4, for example 400 k.
In order to prevent the phases of the high frequency powers from overlapping each other as Hz, the high frequency powers are feedback-controlled so that the negative self-bias voltage applied to the ceramic base material 1 held by the holding electrode 3 becomes 200V. Yes, under these conditions, processing is performed for 1 minute.

Further, when the frequencies of the high frequencies applied to the holding electrode 3 and the counter electrode 4 are the same, the phases of the high frequencies applied to the holding electrode 3 and the counter electrode 4 are controlled so as to be shifted,
It is preferable that both high frequency powers do not interfere with each other. In this case, for example, as shown in FIG. 6, the phase shifter 25 is connected to each of the high-frequency power sources 5 and 5 that supply high-frequency power to the holding electrode 3 and the counter electrode 4, and the holding electrode 3 is connected by the phase shifter 25. And the phase of the high frequency supplied to the counter electrode 4 is controlled to be shifted by a predetermined angle (for example, π (radian)).

The supply condition of the high frequency power to the holding electrode 3 and the counter electrode 4 at this time is appropriately set. For example, the supply condition of the high frequency power applied to the counter electrode 4 is set to a frequency of 13.5.
The frequency of the high frequency power applied to the holding electrode 3 is 13.56, which is the same as that of the counter electrode 4.
The high frequency power is feedback-controlled so that the negative self-bias voltage applied to the ceramic substrate 1 held by the holding electrode 3 is 200 V, and processing is performed for 1 minute under these conditions. is there.

In the above example, only oxygen gas is used as the atmosphere gas for plasma generation during the surface modification treatment, but argon gas may be used together with oxygen gas. In the example shown in FIG. 7, in the configuration shown in FIG. 3, an argon gas introducing port 13a and an oxygen gas introducing port 13b are provided as the gas introducing port 13, and an argon gas and an oxygen gas are supplied from each gas introducing port 13 to a chamber. It is planned to be introduced within 11.

In this case, the ceramic base material 1 is held on the holding electrode 3 and set in the chamber 11, and the inside of the chamber 11 is evacuated to, for example, 10 inside.
After depressurizing to about ^-4 Pa, an argon gas inlet 13a as an atmosphere gas for plasma generation in the chamber 11
Argon gas is introduced from the oxygen gas inlet 1
Oxygen gas is introduced from 3b. Chamber 1 at this time
The conditions such as the ratio of the argon gas to the oxygen gas in the atmosphere in 1 and the total pressure of the atmosphere gas in the chamber 11 are appropriately set. For example, the flow rate ratio of the argon gas to the oxygen gas is 1: 1. At the same time, the total pressure of the atmospheric gas in the chamber 11 is set to about 10 Pa.

In this state, when the high frequency power is supplied to the holding electrode 3 or the high frequency power is independently supplied to the holding electrode 3 and the counter electrode 4 as in the above case, the holding electrode 3 and the counter electrode 4 are supplied. Due to the gas discharge phenomenon due to the glow discharge during the period, the argon gas and the oxygen gas are ionized to generate the plasma P.

At this time, argon ions in the plasma P collide with the ceramic base material 1 and act on the surface of the ceramic base material 1 in the same manner as oxygen ions, and the ceramic base material 1
The cleaning is performed to remove the contaminants 14 on the surface of the oxygen ion. At this time, the mass of argon ions is larger than that of oxygen ions. The surface is cleaned at. Further, the collision of the argon ions having a high sputter rate with the ceramic base material 1 causes the cleavage of the metal-nitrogen bond of the nitride-based ceramics and the metal-carbon bond of the carbide-based ceramics constituting the ceramic base material 1. The formation of the oxide layer 15 on the surface of the ceramic substrate 1 is further promoted by further promotion and introduction of oxygen at the site where this bond is cleaved.

When argon gas and oxygen gas are used together as an atmosphere gas in the surface modification treatment, first, plasma treatment is performed in an argon gas atmosphere,
Subsequently, oxygen gas may be introduced to subsequently perform plasma treatment, and thus stepwise plasma treatment may be performed. In this case, the surface of the ceramic substrate 1 is highly efficiently cleaned and the cleavage of the metal-carbon bond or the metal-nitrogen bond on the surface of the ceramic substrate 1 is promoted by the plasma treatment in an argon gas atmosphere, and then the oxygen is continuously removed. By the plasma treatment in the gas atmosphere, the oxide layer 15 can be formed and the surface of the oxide layer 15 can be activated, so that the oxide layer 15 can be efficiently formed. Oxide layer 1 formed
It is possible to prevent 5 from being etched and removed by sputtering with argon ions having a high sputtering rate.

For example, as shown in FIG. 8 (a), first, only the argon gas is supplied into the chamber 11 and plasma processing is performed in the argon gas atmosphere, so that the surface of the ceramic substrate 1 is raised by the argon gas ions. It efficiently cleans and promotes the cleavage of the bond between the metal of the nitride-based ceramics and the nitrogen and the bond between the metal and the carbon of the carbide-based ceramics that form the ceramic substrate 1. Then, after a lapse of a certain time, the supply of the argon gas is stopped, the processing is once stopped, and then the oxygen gas is supplied into the chamber 11 to perform the plasma processing for a certain time in the oxygen gas atmosphere. Ions form an oxide layer 15 on the surface of the ceramic substrate 1 and activate the surface of the oxide layer 15.

Further, as shown in FIG. 8B, first, only the argon gas is supplied into the chamber 11 to perform the plasma treatment in the argon gas atmosphere, so that the surface of the ceramic substrate 1 is highly efficiently treated with the argon gas ions. In addition to cleaning, the bond between the metal of the nitride-based ceramics and nitrogen forming the ceramic base material 1 and the cleavage of the bond between the metal and the carbon of the carbide-based ceramics that form the ceramic substrate 1 are promoted. Then, after a lapse of a certain time, oxygen gas is supplied into the chamber 11 while the argon gas is being supplied, and the plasma treatment is repeated in a state where the argon gas and the oxygen gas coexist. The formation of the oxide layer 15 by the ions and the activation of the surface of the oxide layer 15 are started. Then
After a lapse of a certain time, the supply of the argon gas is stopped while the oxygen gas is being supplied, the plasma treatment is performed for a certain time in the oxygen gas atmosphere, and the treatment is completed. In this case, the plasma treatment can be performed without interruption.

Here, after the plasma treatment in the argon gas atmosphere as shown in FIG. 8A, the treatment is temporarily interrupted and then the plasma treatment in the oxygen gas atmosphere is performed. After the plasma treatment in the oxygen gas atmosphere is completed and before the plasma treatment in the oxygen gas atmosphere is performed, residual impurity gas is adsorbed on the surface of the activated ceramic substrate 1 to generate plasma in the oxygen gas atmosphere. The processing effect may be reduced. Also, FIG.
When the plasma treatment is performed in a state where the argon gas and the oxygen gas coexist by providing a time in which both the argon gas and the oxygen gas exist in the chamber 11 as in the case shown in (b), Chamber 11
When both the argon gas and the oxygen gas are present in the interior, if the total pressure of the gas becomes high, the transition from the glow discharge to the arc discharge is likely to occur, and the ceramic base material 1 may be damaged by the arc.

Therefore, the gas pressure in the atmosphere is controlled through the plasma processing in the argon gas atmosphere, the plasma processing in the state where the argon gas and the oxygen gas coexist, and the plasma processing in the oxygen gas atmosphere. It is good to keep it constant.

That is, as shown in FIG. 9B, argon gas is first introduced into the chamber 11 in which the ceramic substrate 1 is set, plasma processing is performed in an argon gas atmosphere, and then the chamber 11 is filled. While the introduction flow rate of the argon gas is reduced, the introduction of the oxygen gas is started to increase the introduction amount, the plasma treatment is performed in the atmosphere in which the argon gas and the oxygen gas coexist, and then the chamber 1
In the chamber 11, the introduction of the argon gas into the chamber 1 is stopped and the introduction of the oxygen gas is continued, and the plasma treatment is performed in the oxygen gas atmosphere. During each treatment, the flow rates of the argon gas and the oxygen gas are adjusted. The total gas pressure of is always constant. Further, in the case of FIG. 9A, the gas pressure of the argon gas is set to be large at first and then gradually reduced, and the gas pressure of the oxygen gas is initially set to be small.
After that, the chamber 11 is set to be gradually larger.
The total gas pressure inside is always constant.

The capacitively coupled plasma (CC
In the surface modification treatment according to P), the device structure can be simplified and a large area ceramic substrate 1
The surface modification treatment can be easily performed, and thus the productivity is high. Further, the surface modification treatment by plasma treatment is not limited to the above-mentioned one, and may be treatment by inductively coupled plasma (ICP), surface wave plasma (SWP) or the like.

Next, a metal film is formed on the ceramic substrate 1 which has been subjected to such a surface modification treatment by an appropriate method such as a physical vapor deposition method such as sputtering or ion plating.

FIG. 10 shows an example of the sputtering chamber 9, which is formed as a DC sputtering processing apparatus for forming a metal film by plasma sputtering. Here, a flat plate-shaped substrate holder 18 is provided in the chamber 17.
And targets 19 made of a metal such as copper, aluminum, nickel, or a nickel-chromium alloy are arranged so as to face each other in parallel. The target 19 is connected to the negative electrode of the DC power supply 20, and the positive electrode of the DC power supply 20 is connected to the chamber 17 and is grounded via the chamber 17. In addition, the substrate holder 18 is a chamber 17
And is grounded through the chamber 17. The substrate holder 18 holds the ceramic base material 1 on the side facing the target 19. Further, the chamber 17 is provided with a gas introduction port 21 so that an atmospheric gas for plasma generation can be introduced into the chamber 17 from the gas introduction port 21.

At the time of forming a metal film by plasma sputtering, the ceramic base material 1 after the above surface modification treatment is held in the substrate holder 18 and set in the chamber 17, and the inside of the chamber 17 is set to a vacuum pump or the like. And the inside of the chamber 17 is decompressed to, for example, about 10 ⁻⁴ Pa, and then the chamber 17 is introduced from the gas inlet 21.
Argon gas is introduced as an atmosphere gas for plasma generation. The gas pressure of the argon gas in the chamber 17 at this time is set to about 0.1 Pa, for example.

In this state, the target 19 is connected to the DC power source 2
By applying a DC negative voltage from 0, the argon gas is ionized by the gas discharge phenomenon due to the glow discharge between the substrate holder 18 and the target 19 and the plasma P is generated.
Is generated. The supply condition of the DC voltage at this time is appropriately set, but for example, the output is 2 kW.

At this time, the argon ions in the plasma P collide with the target 19 and the metal particles are repelled from the target 19, and the metal particles are deposited on the surface-modified ceramic substrate 1. The metal film is formed.

Then, after forming the metal film by sputtering to a desired thickness (for example, 5 μm) in this way, the substrate holder 18 is moved to the take-out chamber 10, and the ceramic substrate 1 is taken out from the take-out chamber 10. To take out.

In addition, in the above-described metal film forming process by plasma sputtering, only the argon gas is used as the atmosphere gas for plasma generation to form the metal film by sputtering. A layer made of a metal oxide may be formed by reactive sputtering using oxygen gas as a gas together with argon gas. For example, in the example shown in FIG. 11, in the configuration shown in FIG. 10, an argon gas introduction port 21a and an oxygen gas introduction port 21b are provided as the gas introduction port 21, and an argon gas and an oxygen gas are supplied from each gas introduction port 21. It is arranged to be introduced into the chamber 17.

In this case, the surface-modified ceramic base material 1 is held in the substrate holder 18 and set in the chamber 17, and the inside of the chamber 17 is evacuated to, for example, 10 ^-4. After reducing the pressure to about Pa level, argon gas is introduced into the chamber 17 as an atmosphere gas for plasma generation from the argon gas inlet 21a and oxygen gas is introduced from the oxygen gas inlet 21b. At this time, conditions such as the ratio of argon gas to oxygen gas in the atmosphere in the chamber 17 and the total pressure of the atmosphere gas in the chamber 17 are appropriately set. For example, the supply amounts of the argon gas and the oxygen gas are 1: 1 and the total pressure of the atmospheric gas in the chamber 17 is 0.1 Pa
Try to be around.

In this state, when a DC voltage is applied to the target 19 in the same manner as in the above case, the argon gas and the oxygen gas are ionized by the gas discharge phenomenon due to the glow discharge between the substrate holder 18 and the target 19 and the plasma is generated. P produces. The supply condition of the DC voltage at this time is appropriately set, but for example, the output is 2 kW.

At this time, the argon ions in the plasma P collide with the target 19 to repel metal particles from the target 19, and the metal particles react with oxygen ions in the plasma P to generate metal oxides. Then, this metal oxide is deposited on the ceramic substrate 1,
A layer of metal oxide is formed.

Next, after a lapse of a certain time (for example, 10 seconds) from the start of the plasma sputtering, the supply amount of oxygen gas to the chamber 17 is gradually reduced to increase the ratio of argon gas in the atmosphere. Plasma sputtering is continuously performed, and finally plasma sputtering is performed in an argon gas atmosphere.
When reducing the supply amount of oxygen gas, it is preferable to adjust the gas supply amount so that the total pressure of the atmospheric gas in the chamber 17 is maintained constant.

At this time, the metal oxide is deposited on the surface layer side portion of the ceramic base material 1 of the layer made of the metal oxide by the reactive sputtering and the metal is also deposited because the ratio of oxygen gas in the atmosphere is reduced. As a result, the metal oxide and the metal are mixed and the metal content increases. Further, when the atmosphere in the chamber 17 becomes an argon gas atmosphere, a metal film made of only metal is formed on the surface side of the layer made of metal oxide. Then, plasma sputtering is performed in an argon gas atmosphere until the thickness of the metal film reaches a desired thickness (for example, 0.5 μm).

In this way, a metal film is formed on the oxide layer 15 formed by the surface modification treatment via the metal oxide formed by reactive sputtering, and both are made of oxide. The oxide layer 15 and the metal oxide layer are formed with good adhesion, and the metal film and the metal oxide layer are formed with good adhesion. It is formed with better adhesion. Further, in the surface side portion of the metal oxide layer, a composition gradient is formed such that the metal content relative to the metal oxide increases toward the surface side. Formed well, and the adhesion of the metal film is further improved.

When the metal film is formed by plasma sputtering as described above, the ion beam 6 may be irradiated as an assist. In the structure shown in FIG. 12, the ion gun 22 is provided in the chamber 17, and the ion gun 22 is connected to the ceramic substrate 1.
The ion beam 6 can be irradiated toward
As the ion gun 22, an ion gun 22a for irradiating the ion beam 6 of argon can be provided, and in this case, for example, a filament type such as a Kauffman type can be used. Then, the ceramics base material 1 subjected to the surface modification treatment is held and set on the substrate holder 18, and the inside of the chamber 17 is set to, for example, 10 by a vacuum pump.
^{-Evacuate to the level of -4} Pa and supply argon gas to chamber 1.
7, while supplying a gas pressure in the chamber 17 to about 0.1 Pa while supplying a DC voltage to the target 19 at an output of about 2 kW, plasma P
Can be generated to form a metal film. At the same time, the ion beam 6 of argon is generated from the ion gun 22a under the conditions of, for example, an acceleration voltage of 500 V and a beam current of 150 mA.
By irradiating with, the metal particles can be assisted to be pushed into the surface-modified oxide layer 15 of the surface-modified ceramic substrate 1, and the metal film can be formed with even better adhesion.

When assisting the irradiation of the ion beam 6 from the ion gun 22, the ion gun 22b for irradiating the oxygen ion beam 6 is used as the ion gun 22 so that the oxygen ion beam 6 is irradiated from the ion gun 22b. As a result, a layer made of a metal oxide can be formed on the surface of the ceramic base material 1 and further a metal film can be formed by plasma sputtering in an argon gas atmosphere.

In this case, for example, the ceramic base material 1 subjected to the surface modification treatment is held and set on the substrate holder 18, and the inside of the chamber 17 is set to 10 ⁻⁴ by a vacuum pump.
Vacuum is evacuated to Pa level, and argon gas is supplied to the chamber 17
While supplying the gas pressure in the chamber 17 to about 0.1 Pa, a DC voltage is output to the target 19.
By supplying at about kW, plasma P is generated, and at the same time, an acceleration voltage of 500 from the ion gun 22b.
The oxygen ion beam 6 is irradiated under the conditions of V and a beam current of 150 mA. At this time, the argon ions in the plasma P collide with the target 19 and the metal particles are repelled from the target 19, and the metal particles are generated by the ion gun 2.
2b reacts with oxygen ions irradiated from 2b to generate a metal oxide, and the metal oxide is subjected to a surface modification treatment by an oxygen ion beam 6 to form a surface oxide layer of the ceramic substrate 1. It is possible to assist in pushing into 15, and a layer made of a metal oxide can be formed with better adhesion. In addition, after a lapse of a certain time after starting the plasma sputtering, the irradiation amount of the oxygen ion beam 6 from the ion beam 6 is gradually reduced,
Eventually, when plasma sputtering is performed with the irradiation of the ion beam 6 stopped, the metal oxide is deposited on the surface layer side portion of the ceramic base material 1 of the layer made of the metal oxide, and in the atmosphere. Since the irradiation dose of the oxygen ion beam 6 decreases, the metal is also deposited, the metal oxide and the metal are mixed, and the metal content increases toward the surface layer side. When the irradiation is stopped, a metal film made of only metal is formed on the surface layer side of the layer made of metal oxide. Then, plasma sputtering is performed in an argon gas atmosphere until the thickness of the metal film reaches a desired thickness (for example, 0.5 μm).

By doing so, the adhesion of the metal oxide layer is further enhanced by the assist of pushing the metal oxide particles or the metal oxide particles and the metal particles with the oxygen ion beam 6. By adjusting the irradiation amount of the ion beam 6 of oxygen from the ion gun, the contents of the metal oxide and the metal in the layer made of the metal oxide can be easily adjusted, and the atmosphere containing the argon gas and the oxygen gas can be adjusted. It is easier to control the composition ratio of the metal oxide and the metal in the layer composed of the metal oxide than in the case where the layer composed of the metal oxide is formed by reactive sputtering.

When the ion beam 6 is irradiated with the active gas such as the oxygen gas as described above, the ion gun 2 is used.
As 2b, it is necessary to use a non-filament type such as RF type or ECR type.

In the above description, when the metal film is formed by plasma sputtering, the ceramic substrate 1 after the surface modification treatment is held in the substrate holder 18 and set in the chamber 17, and then the chamber 17 is vacuumed. Although a vacuum is evacuated by a pump or the like, R
By connecting the intake path to the chamber 11 of the F plasma chamber 8 and the intake path to the chamber 17 of the sputter chamber 9, the chamber of the sputter chamber 9 is simultaneously evacuated when the chamber 11 of the RF plasma chamber 8 is evacuated. 17
The interior of the ceramic substrate 1 is also evacuated and surface-modified.
Can also be moved and set in the vacuumed chamber 17.

[0070]

As described above, in the method for forming a metal film on a ceramic substrate according to claim 1 of the present invention, after a nitride-based or carbide-based ceramic substrate is subjected to surface modification treatment with oxygen plasma. By forming a metal film, the surface of the ceramic substrate is cleaned by the surface modification treatment, an oxide layer is formed, and the surface of the oxide layer is further activated to remove the oxide layer. It is possible to form a metal film through this, and thereby a metal film can be formed with good adhesion to a nitride-based or carbide-based ceramic substrate.

A second aspect of the present invention is to form a metal film by vapor deposition, sputtering or ion plating on the substrate which has been surface-modified with oxygen plasma according to the first or second aspect. By the method described above, the metal film can be formed with good adhesion to the ceramic substrate.

According to a third aspect of the present invention, in the first aspect, the holding electrode holding the ceramic base material and the counter electrode are arranged to face each other, and an atmosphere containing oxygen gas is provided between the holding electrode and the counter electrode. Since the surface modification treatment is performed by supplying high frequency power to the holding electrode with a high frequency power source in the presence of gas, the surface modification treatment can be performed by high frequency plasma, and at the same time, the ceramics of a large area can be formed with a simple structure. The substrate can be treated and the productivity is high.

Further, in the invention of claim 4, in claim 3, since high-frequency power is supplied to the holding electrode and the counter electrode by independent high-frequency power sources during the surface modification treatment,
The density of the plasma generated in the space between the holding electrode and the counter electrode can be adjusted by controlling the high frequency power supplied to the counter electrode, and the energy at the time of collision of ions with the ceramic substrate is retained. It can be adjusted by controlling the high frequency power supplied to the electrodes, and the density of the generated plasma and the energy at the time of collision of ions with the ceramic substrate can be controlled independently and independently. Therefore, optimal conditions can be taken. For example, even if the density of the generated plasma is increased to improve the processing efficiency, the collision energy of the ions with respect to the ceramic base material can be appropriately maintained.

According to a fifth aspect of the present invention, in the third or fourth aspect, the oxygen gas and the argon gas are contained in the atmosphere gas between the holding electrode and the counter electrode at the time of the surface modification treatment. The surface of the ceramic substrate is highly efficiently cleaned with argon ions having a larger mass than that, and the metal-nitrogen bond of the nitride ceramics and the metal-carbon bond of the carbide ceramics that compose the ceramic substrate are cleaved. The formation of an oxide layer on the surface of the ceramic substrate can be further promoted.

According to a sixth aspect of the present invention, in the fifth aspect, during the surface modification treatment, the plasma treatment is first performed in an argon gas atmosphere, and then oxygen gas is introduced to subsequently perform the plasma treatment. The plasma treatment in the atmosphere highly efficiently cleans the surface of the ceramic substrate and promotes the cleavage of the metal-carbon bond or the metal-nitrogen bond on the surface of the ceramic substrate, and subsequently oxidizes by the plasma treatment in the oxygen gas atmosphere. Of the oxide layer and the surface activation of the oxide layer, the oxide layer is efficiently formed, and the oxide layer formed by the plasma treatment in the oxygen gas atmosphere has a high sputtering rate. It can prevent things from being etched and removed by sputtering with argon ions. That.

According to a seventh aspect of the present invention, in the sixth aspect, between the holding electrode and the counter electrode, the total pressure of the atmosphere gas between the holding electrode and the counter electrode during the surface modification treatment is kept constant. Since the argon gas and the oxygen gas are supplied to the substrate, the surface modification treatment by the plasma of the argon gas and the plasma of the oxygen gas is performed without interruption, and the gas of the residual impurities on the surface of the ceramic substrate before the treatment by the plasma of the oxygen gas is performed. Can be prevented from being adsorbed, and at the same time, the total pressure of the atmospheric gas can be prevented from becoming too high and the ceramic base material from being damaged by the arc.

The invention according to claim 8 is the method according to any one of claims 1 to 7, wherein a metal oxide is formed by reactive sputtering on the surface of the surface-modified ceramic substrate, and sputtering is performed on this surface. Since the metal film is formed by, the metal film can be formed on the oxide layer formed by the surface modification treatment via the metal oxide,
An oxide layer composed of an oxide and a metal oxide are both formed with good adhesion, and a metal film and a metal oxide are formed with good adhesion, and a metal film is formed on a ceramic substrate with even better adhesion. Is something that can be done.

The invention according to claim 9 is the method according to claim 8, wherein when the metal oxide is formed by reactive sputtering, the oxygen gas concentration in the atmosphere is continuously decreased to form a layer made of the metal oxide. Since the composition gradient is formed such that the metal content with respect to the metal oxide increases toward the surface layer side, the adhesion between the subsequently formed metal film and the layer composed of the metal oxide is further improved, and the ceramic substrate In addition, a metal film can be formed with better adhesion.

Further, the invention of claim 10 is based on claims 1 to 9.
In any of the above, when a metal film is formed on the surface of the ceramic base material that has been subjected to the surface modification treatment by irradiation with an argon ion beam, the metal particles are sputtered onto the surface of the ceramic base material during sputtering. It is possible to perform pushing assist with an ion beam and to form a metal film with even better adhesion.

Further, the invention of claim 11 is based on claims 1 to 7.
And in any one of Claim 10, when forming a metal film by sputtering on the surface of the ceramics base material which carried out the surface modification treatment, since it is irradiated with an oxygen ion beam, the metal particles and the ion gun are used for the sputtering. A metal oxide can be formed by reacting with irradiated oxygen ions to form a metal oxide, and the metal oxide can be deposited on the oxide layer of the surface layer of the ceramic substrate to form a metal oxide layer. A metal film can be formed through a layer made of an oxide, and an oxide layer made of an oxide and a layer made of a metal oxide are both formed with good adhesion,
It is possible to form a metal film and a layer composed of a metal oxide with good adhesion, and to form a metal film on a ceramic substrate with even better adhesion. Furthermore, when forming the layer made of the metal oxide, the ion beam of oxygen can assist in pushing the metal oxide particles into the surface layer of the ceramic substrate, and the layer made of the metal oxide can be formed with good adhesion. The metal film can be formed with better adhesion. Furthermore, the composition ratio of the metal oxide and the metal in the layer composed of the metal oxide can be easily controlled by adjusting the irradiation amount of the oxygen ion beam.

[Brief description of drawings]

1A to 1D are schematic cross-sectional views showing a surface modification treatment step for a ceramic substrate.

FIG. 2 is a schematic view showing an example of a metal film forming step on a ceramic substrate in the present invention.

FIG. 3 is a schematic view showing an example of a high frequency plasma processing apparatus.

FIG. 4 is a schematic view showing another example of a high frequency plasma processing apparatus.

FIG. 5 is a schematic view showing another example of a high frequency plasma processing apparatus.

FIG. 6 is a schematic view showing another example of a high frequency plasma processing apparatus.

FIG. 7 is a schematic view showing another example of a high frequency plasma processing apparatus.

8A and 8B are graphs showing an example of the gas supply amount into the chamber during the surface modification treatment.

9A and 9B are graphs showing an example of the gas supply amount into the chamber during the surface modification treatment.

FIG. 10 is a schematic view showing an example of a DC plasma sputtering processing apparatus.

FIG. 11 is a schematic view showing another example of the DC plasma sputtering processing apparatus.

FIG. 12 is a schematic view showing another example of the DC plasma sputtering processing apparatus.

FIG. 13 is a schematic view showing an example of a conventional metal film forming step on a ceramic substrate.

FIG. 14 is a schematic diagram showing a conventional high-frequency plasma processing apparatus.

15 (a) to (c) are schematic cross-sectional views showing a conventional surface modification treatment step for a ceramic substrate.

[Explanation of symbols]

1 Ceramics substrate 3 holding electrode 4 Counter electrode 5 high frequency power supply 6 ion beam

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/14 H05K 3/14 A 3/16 3/16 3/38 3/38 A (72) Inventor Tomoyuki Kawahara 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Inventor Hitoshi Kimura 1048, Kadoma, Kadoma City, Osaka Prefecture F Term (Reference) 4K029 AA04 BA01 BA08 BA43 BB02 BC00 BD02 CA01 CA03 CA05 CA06 DC35 EA05 FA05 5E343 AA02 AA23 AA35 AA36 BB71 DD23 DD24 DD25 EE36 GG02 GG04

Claims (11)

[Claims] 1. A nitride-based or carbide-based ceramic substrate is subjected to surface modification treatment with oxygen plasma,
A method for forming a metal film on a ceramic substrate, which comprises forming a metal film. 2. The method for forming a metal film on a ceramic substrate according to claim 1, wherein the metal film is formed by vapor deposition, sputtering or ion plating on the substrate which has been subjected to the surface modification treatment with oxygen plasma. . 3. A holding electrode for holding a ceramic substrate and a counter electrode are arranged to face each other, and a high frequency power source is applied to the holding electrode in a state where an atmosphere gas containing oxygen gas exists between the holding electrode and the counter electrode. The method for forming a metal film on a ceramic substrate according to claim 1 or 2, wherein the surface modification treatment is performed by supplying high-frequency electric power. 4. The method for forming a metal film on a ceramic substrate according to claim 3, wherein high frequency power is supplied to the holding electrode and the counter electrode by independent high frequency power sources during the surface modification treatment. 5. The ceramic base material according to claim 3, wherein the atmosphere gas between the holding electrode and the counter electrode contains oxygen gas and argon gas during the surface modification treatment. Metal film forming method. 6. The ceramic substrate according to claim 5, wherein during the surface modification treatment, plasma treatment is first performed in an argon gas atmosphere, and then oxygen gas is introduced to subsequently perform plasma treatment. Metal film forming method. 7. During the surface modification treatment, argon gas and oxygen gas are supplied between the holding electrode and the counter electrode so that the total pressure of the atmospheric gas between the holding electrode and the counter electrode is constant. The method for forming a metal film on a ceramic substrate according to claim 6, which is characterized in that. 8. The method according to claim 1, wherein a metal oxide is formed by reactive sputtering on the surface of the surface-modified ceramic substrate, and a metal film is formed on the surface by sputtering. A method for forming a metal film on the ceramic substrate according to any one of 1. 9. When forming a metal oxide by reactive sputtering, the oxygen gas concentration in the atmosphere is continuously reduced so that the metal oxide layer has a metal content relative to the surface layer side. 9. The method for forming a metal film on a ceramic substrate according to claim 8, wherein the composition gradient is increased. 10. The ion beam of argon is irradiated when a metal film is formed on the surface of a ceramic substrate which has been subjected to a surface modification treatment by sputtering. A method for forming a metal film on the ceramic substrate according to claim 1. 11. The method according to claim 1, wherein when a metal film is formed on the surface of the ceramic base material subjected to the surface modification treatment by sputtering, the ion beam of oxygen is irradiated. 11. The method for forming a metal film on the ceramic substrate according to any one of 10.