KR20230106210A - Diffusion bonding apparatus and methods using remote plasma - Google Patents

Abstract

The present invention provides a diffusion bonding device and method capable of efficiently forming a bonding layer capable of effectively removing a contamination layer on the surface of a bonding part in diffusion bonding of solid objects and also strengthening bonding between the bonding parts of objects to be bonded. aims to do In order to achieve the above object, in the present invention, a chamber for accommodating objects to be bonded, a vacuum unit for creating a vacuum state in the chamber, a plasma generator disposed outside the chamber, and a plasma gas formed through the plasma generator It is possible to provide a diffusion bonding device using external plasma including a plasma induction unit for inducing entry into the chamber, a heating unit disposed in the chamber for heating a bonding portion of the bonding object, and a pressurizing unit for pressurizing the bonding object.

Description

Diffusion bonding device and method using remote plasma {DIFFUSION BONDING APPARATUS AND METHODS USING REMOTE PLASMA}

The present invention relates to a diffusion bonding apparatus and method, and more particularly, to effectively remove contaminants formed on the surface of an object to be bonded or to bond by disposing a plasma generator outside and injecting a plasma gas generated therefrom into a chamber for diffusion bonding. It relates to a diffusion bonding device and method capable of forming a bonding layer capable of reinforcing.

In general, solid state bonding is a technology of integrating objects to be joined while maintaining them in a solid state, unlike conventional fusion welding. This technology is a technology that can maximize the characteristics of an integrated part by preserving the original characteristics of the joined body by preventing or maximally suppressing the melting of the joined body and minimizing the occurrence of defects in the joint. With the development of new metal materials such as composite materials and the development of high-tech industries, solid-state bonding technology has been greatly spotlighted and developed. As a result, materials that cannot be joined with conventional fusion welding technology, materials with complex shapes, and high quality and precision are required. It is now possible to join materials, etc.

Such solid-state bonding techniques include friction bonding using frictional heat, brazing using intercalated metal, and diffusion bonding using atomic diffusion. Among them, diffusion bonding is a method of bonding in a solid state by applying a pressure at a high temperature that does not melt the bonded objects and does not cause large plastic deformation.

At this time, the temperature, pressing force, etc. are adjusted according to the degree of allowable plastic deformation, and most of the bonded products apply the minimum temperature, pressing force, heating time, etc. enough to ensure sufficient bonding to minimize thermal deformation. In particular, ultra-precision products such as molds designed with cooling water channels are classified as defective even if thermal deformation of about 0.1 mm occurs.

In addition, another major process variable of diffusion bonding is the surface condition of the bonding surface, and the degree of bonding varies depending on the surface condition even under the same pressure and heating conditions. The surface condition includes surface roughness, surface contamination layer thickness, oxide film thickness, etc., and surface roughness and surface contamination layer can be prepared by surface precision polishing, cleaning, etc., but oxide film is the biggest problem. That is, no matter how much the oxide film is removed through polishing or the like in the previous step, oxidation occurs during preparation for the diffusion bonding process and charging, or even during heating and maintenance. Therefore, diffusion bonding is normally performed in an inert gas such as high purity Ar or N2 or in a vacuum atmosphere, or in a reducing atmosphere such as hydrogen.

While this conventional diffusion bonding requires a temperature of 600 ~ 1,000 ℃ depending on the material, the hydrogen reduction reaction takes a long time at a high temperature that requires a higher temperature of 800 ~ 1,300 ℃, so it is difficult to completely remove the oxide film in the actual process. impossible. Therefore, the principle of bringing pure metal surfaces into contact with each other while destroying the oxide film by applying high pressure in a state where the oxide film is not completely removed for diffusion bonding in a given time is usually used.

That is, more than the pressure and temperature required for bonding of pure metal surfaces without an oxide film are required, and the degree of excess varies depending on the thickness of the oxide film, such as appropriate pressure, heating temperature, and time. In addition, since accurately measuring the thickness of an oxide film caused by oxygen or moisture in the air is a highly difficult technique that requires expensive equipment, there is a problem in that the work is performed without accurately determining the thickness of the oxide layer in the field. Therefore, there are many problems such as the degree of bonding or bonding strength of products shipped after completion of the process, which are different each time, and cause serious bonding defects in some products.

In order to solve this problem, there is a recent prior art having a plasma processing device in a reaction chamber. To this end, the internal structure of the chamber is complicated to form plasma therein, and there is a problem in that control is difficult.

In addition, as the whole to-be-bonded objects are etched by the plasma generated inside the chamber, there is a problem in that the objects to be bonded are damaged and the etching efficiency is lowered.

Korean Registered Patent No. 10-2037368

The present invention provides a diffusion bonding device and method capable of efficiently forming a bonding layer capable of effectively removing a contamination layer on the surface of a bonding part in diffusion bonding of solid objects and also strengthening bonding between the bonding parts of objects to be bonded. aims to do

In order to achieve the above object, in the present invention, a chamber for accommodating objects to be bonded, a vacuum unit for creating a vacuum state in the chamber, a plasma generator disposed outside the chamber, and a plasma gas formed through the plasma generator It is possible to provide a diffusion bonding device using external plasma including a plasma induction unit for inducing entry into the chamber, a heating unit disposed in the chamber for heating a bonding portion of the bonding object, and a pressurizing unit for pressurizing the bonding object.

In addition, in the diffusion bonding device using external plasma according to the present invention, the heating source of the heating part may be any one of an IR heater, a halogen heater, and a laser capable of locally heating the bonding part of the object to be bonded.

In addition, in the diffusion bonding apparatus using external plasma according to the present invention, the plasma gas may be an etching gas for removing a contamination layer formed on a surface of a junction of the object to be bonded.

In addition, in the diffusion bonding apparatus using external plasma according to the present invention, the plasma gas may be an atomic layer deposition gas for forming a bonding layer for bonding reinforcement on the surface of the bonding object.

On the other hand, the diffusion bonding method provided by the present invention to achieve the above object is to place objects to be bonded in a chamber, vacuum step to make the chamber in a vacuum state, and heating to heat the junction of the objects to be bonded. Step, a first plasma injection step of generating a first plasma gas for removing the contamination layer formed on the surface of the junction from the outside of the chamber and injecting the first plasma gas into the chamber, the injected first plasma gas and a diffusion bonding step of joining the objects to be bonded by pressurizing the heated and joint portions from which the contamination layer is removed.

In addition, the first plasma gas is generated from one or more gases selected from SiF ₄ , CF ₄ , C ₃ F ₈ , C ₂ F ₆ , CHF ₃ , CClF ₃ , NF ₃ , SF ₆ , O ₂ and H ₂ It may be a plasma state gas.

Another diffusion bonding method using external plasma that can be provided in the present invention includes the steps of disposing an object to be bonded in a chamber, a vacuum step of making the chamber in a vacuum state, a heating step of heating the junction of the object to be joined, and the chamber. A second plasma injection step of generating a second plasma gas for forming a bonding layer for bonding reinforcement on the surface of the bonding part of the bonding object from the outside and injecting the second plasma gas into the chamber, the injected second A bonding layer deposition step of forming the bonding layer through a plasma gas and a diffusion bonding step of bonding the objects to be bonded by pressurizing the heated bonding layer formed with each other.

In addition, the second plasma gas is SiH ₄ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , GeH ₄ , B ₂ H ₆ , BBr _{3 , BCl 3} , AsH ₃ , PH ₃ , TeH ₂ , SnCl ₄ , GeCl ₄ , It may be a plasma state gas generated from one or more gases selected from WF ₆ , NH ₃ , CH ₄ , Cl ₂ , and MoF ₆ .

In addition, before the second plasma injection step, a first plasma injection for generating the first plasma gas for removing the contamination layer formed on the surface of the junction outside the chamber and injecting the first plasma gas into the chamber and a contamination layer removal step of removing the contamination layer formed on the surface of the junction of the object to be bonded through the injected first plasma gas.

Through the diffusion bonding apparatus and method using external plasma according to the present invention, it is possible to increase the bonding strength and reliability of diffusion bonded products.

1 is a schematic diagram of a diffusion bonding device according to the present invention.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, when a certain part 'includes' a certain component, this means that it may further include other components without excluding other components unless otherwise stated.

A diffusion bonding device using an external plasma according to the present invention includes a chamber accommodating objects to be bonded, a vacuum unit that creates a vacuum state in the chamber, a plasma generator disposed outside the chamber, and a plasma gas formed through the plasma generator. It may include a plasma induction unit for inducing entry into the chamber, a heating unit disposed in the chamber for heating a junction of the object to be bonded, and a pressurizing unit for pressurizing the object to be bonded.

Diffusion bonding is a technique of bonding by using diffusion of atoms generated between bonding surfaces in a solid state by heating and applying pressure to a bonding portion of an object to be bonded. In stages, plastic deformation similar to high-temperature creep deformation occurs by heating and pressurization, voids existing in the material are spheroidized to reduce interface energy, and voids are reduced by grain boundary diffusion and surface diffusion, grain boundary movement This actively occurs, and the stage in which the void disappears by diffusion occurs in turn. Grain growth or recrystallization often occurs in the final void extinction stage.

In such diffusion bonding, since the surface of the joint directly contacts and bonds by diffusion, it is very important to control the surface to be bonded. The bonding surface is likely to form a film due to oxidation or a film contaminated by contaminants during the process. The contamination layer formed by such an oxide film or contamination film is micronized and dispersed or solidified into the inside of the object to be bonded while being destroyed in the plastic deformation step. In order to destroy such a contamination layer, the temperature needs to be raised to a temperature higher than the temperature required for plastic deformation, and it is easy to cause quality problems such as a decrease in joint strength due to materials of the contamination layer dissolved or dispersed into the inside.

In the present invention, in order to remove the contamination layer formed on the surface of the junction or to form by adding a bonding layer for strengthening the bonding strength to the surface of the junction, a plasma generator is disposed outside the chamber to form a diffusion bonding device using remote plasma. can provide

First of all, the removal of the contamination layer of the bonding surface is a very important factor in controlling the surface. The contamination layer refers to a film layer containing impurities other than the pure bonding object, such as an oxide film and a contamination film formed on the surface of the bonding surface. In particular, when an object to be bonded is a nitride, carbide, metal, or semi-metal material such as silicon, it is difficult to prevent a contamination layer due to the formation of a thin oxide film on the surface when exposed to the air.

The oxide film formed on such a surface not only makes diffusion bonding difficult, but also causes the strength of the bonding part to be weakened due to oxides mixed into the bonding part after diffusion bonding. Therefore, it is very important to remove this oxide film before diffusion bonding.

In the present invention, this oxide film can be removed through plasma gas. Since the contamination layer is removed by the plasma gas injected into the chamber immediately before bonding after the object to be bonded is placed inside the chamber, the contamination layer is removed before bonding after the removal of the contamination layer. Again, there is no fear of contamination of the surface by oxidation or the like.

Also, in the present invention, the plasma gas is generated and injected into the chamber through a remote plasma system in which the plasma gas generated outside the diffusion bonding device is guided into the chamber. Through this, there is no need to provide a complex plasma forming device inside the chamber, so that the diffusion bonding device can be simplified and easily controlled, thereby increasing efficiency.

Meanwhile, in the present invention, the plasma gas may be a deposition gas for atomic layer deposition rather than an etching gas. Diffusion bonding is a method of bonding through diffusion between bonding objects without using other intercalation materials, but when a bonding layer is formed between bonding objects to make bonding more smooth, bonding strength can be increased. Therefore, in the diffusion bonding device according to the present invention, the plasma gas injected into the chamber may be an atomic layer deposition gas that can be deposited as a thin junction on the surface of the junction.

As the bonding material is deposited on the bonding surface of the bonding object through the gas for atomic layer deposition in a plasma state, bonding efficiency can be increased, and bonding strength after bonding can also be increased.

A gas for atomic layer deposition for such a bonding layer may deposit a material different from the bonding object, or to deposit a material containing the same element as the element included in the bonding object, such as silicon or silica, on the surface of quartz, the bonding object. It may be a gas for

Meanwhile, in the diffusion bonding device according to the present invention, the heating unit for heating the junction of objects to be bonded may be an IR heater, a halogen heater, or a laser capable of locally heating the junction.

For diffusion bonding, it is necessary to heat an object to be bonded. In particular, in the present invention, the reaction with the plasma gas is accelerated through such heating so that the removal of the contamination layer on the surface of the junction or the deposition of the junction can be smoothly performed. However, when the entire object to be joined is heated, etching or deposition may occur not only on the surface of the junction but also in other parts. Therefore, it is preferable that heating occurs only on the surface of the joint.

To this end, in the present invention, an IR heater, a halogen heater, and a laser capable of locally heating the surface of the junction are used as a heating source for the heating part, so that the etching effect or deposition effect by the plasma gas can be intensively generated on the surface of the junction.

A schematic diagram of an embodiment of a diffusion bonding device according to the present invention is shown in FIG. 1 . As a diffusion bonding device for bonding objects to be bonded 70, a plasma generator 30 is disposed outside the chamber 10, and the plasma gas generated therefrom flows into the chamber 10 through the plasma induction unit 40. Injected. The bonding object 70 is disposed between the pressing parts 60 for pressurization, and the heating part 50 for locally heating the junction of the bonding object 70 is disposed toward the bonding object 70 . The heating unit may be a UV lamp, a halogen lamp, or a laser. A vacuum device 20 may also be disposed outside the chamber 10 to maintain a vacuum in the chamber.

A diffusion bonding method using an external plasma device according to the present invention includes the steps of disposing an object to be bonded in a chamber, a vacuum step of making the chamber in a vacuum state, a heating step of heating a junction of the object to be joined, and the outside of the chamber. A first plasma gas injection step of generating a first plasma gas for removing a contamination layer formed on a surface of a junction of objects to be bonded and injecting the first plasma gas into the chamber; A contamination layer removal step of removing the contamination layer and a diffusion bonding step of bonding the objects to be bonded by pressing the joint portions from which the contamination layer has been removed by being heated to each other.

The first plasma gas is an etching gas and can remove a contamination layer formed on the surface of the junction. By pressurizing the object to be bonded after the removal of such a contamination layer, diffusion bonding can be performed at a lower temperature and the strength of the bonded portion can be increased after bonding.

Here, the first plasma gas is SiF ₄ , CF ₄ , C ₃ F ₈ , C ₂ F ₆ , CHF ₃ , CClF ₃ , NF ₃ , SF ₆ , O 2 and H ₂ Plasma generated from one or more gases selected from It can be a state gas. By including fluorine or using oxygen or hydrogen, it is possible to effectively remove an oxide film formed on the surface of a semi-metal such as carbide, nitride, metal or silicon.

For example, the object to be bonded may be a focus ring made of SiC used in a semiconductor etching device, and this focus ring may be made of a plurality of parts and assembled. While applying the diffusion bonding method for assembling the SiC focus ring, an oxide film formed on the SiC surface is effectively removed using external plasma in the chamber before diffusion bonding, thereby manufacturing a focus ring having strong bonding strength.

In addition, in the diffusion bonding method using an external plasma device according to the present invention, the plasma gas injected from the outside may be a plasma gas for atomic layer deposition. Bonding strength after bonding can be improved by forming a bonding layer for bonding reinforcement on the surface of a bonding portion of an object to be bonded through the plasma gas for deposition.

The plasma gas for atomic layer deposition is SiH ₄ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , GeH ₄ , B ₂ H ₆ , BBr ₃ , BCl3, AsH ₃ , PH ₃ , TeH ₂ , SnCl ₄ , GeCl ₄ , WF ₆ , NH ₃ , CH ₄ , Cl ₂ , MoF ₆ It may be a plasma state gas generated from one or more types of gases selected from.

Meanwhile, it may be more efficient to additionally remove the surface contamination layer before forming the bonding layer. To this end, the surface contamination layer of the junction may be removed in advance by generating and injecting etching plasma before the deposition plasma injection step for forming the bonding layer. can

Claims (9)

a chamber accommodating the object to be bonded;
a vacuum unit for making the chamber into a vacuum state;
a plasma generator disposed outside the chamber;
a plasma induction unit for inducing the plasma gas formed through the plasma generation unit to enter the chamber;
a heating unit disposed in the chamber and heating a bonding portion of the bonding object; and
Diffusion bonding apparatus using external plasma, including a pressurizing unit for pressurizing the object to be bonded. According to claim 1,
The heating source of the heating unit is any one of an IR heater, a halogen heater, or a laser capable of local heating of the bonding portion of the bonding object, diffusion bonding device using external plasma. According to claim 1,
The plasma gas is an etching gas for removing a contamination layer formed on the surface of the joint of the object to be joined, a diffusion bonding device using an external plasma. According to claim 1,
The plasma gas is an atomic layer deposition gas for forming a bonding layer for strengthening bonding on the surface of the bonding object, a diffusion bonding device using an external plasma. placing the bonding object in the chamber;
a vacuum step of making the chamber into a vacuum state;
a heating step of heating the joint of the object to be joined;
a first plasma gas injection step of generating a first plasma gas for removing a contamination layer formed on a surface of the junction from outside the chamber and injecting the first plasma gas into the chamber;
a contamination layer removing step of removing the contamination layer through the injected first plasma gas; and
Diffusion bonding method using an external plasma, including; a diffusion bonding step of bonding the objects to be bonded by pressing the heated and contaminant layer removed bonding parts to each other. According to claim 5,
The first plasma gas is SiF ₄ , CF ₄ , C ₃ F ₈ , C ₂ F ₆ , CHF ₃ , CClF ₃ , NF ₃ , SF ₆ , O ₂ and H ₂ Plasma generated from one or more gases selected from A diffusion bonding method using an external plasma, which is a state gas. placing the bonding object in the chamber;
a vacuum step of making the chamber into a vacuum state;
a heating step of heating the joint of the object to be joined;
A second plasma gas injection step of generating a second plasma gas for forming a bonding layer for bonding reinforcement on the surface of the bonding portion of the bonding object from outside the chamber and injecting the second plasma gas into the chamber;
a bonding layer deposition step of forming the bonding layer through the injected second plasma gas; and
Diffusion bonding method using an external plasma comprising a; diffusion bonding step of bonding the objects to be bonded by pressurizing the bonding parts where the bonding layer is formed with each other. According to claim 7,
The second plasma gas is SiH ₄ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , GeH ₄ , B ₂ H ₆ , BBr ₃ , BCl 3 , AsH ₃ , PH ₃ , TeH ₂ , SnCl ₄ , GeCl ₄ , WF ₆ , NH ₃ , CH ₄ , Cl ₂ , MoF ₆ is a plasma state gas generated from at least one gas selected from, a diffusion bonding method using an external plasma. According to claim 7,
Before the second plasma gas injection step, a first plasma injection step of generating the first plasma gas for removing the contamination layer formed on the surface of the junction from the outside of the chamber and injecting the first plasma gas into the chamber and a contamination layer removing step of removing the contamination layer formed on the surface of the junction of the object to be bonded through the injected first plasma gas.

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