KR102666967B1 - Diffusion bonding apparatus and methods using remote plasma - Google Patents

Abstract

The present invention provides a diffusion bonding device and method that can effectively remove the contamination layer on the surface of the joint in the diffusion bonding of solid objects and can also efficiently form a bonding layer that can strengthen the bond between the bonding parts of the bonded objects. The purpose is to In order to achieve the above object, the present invention includes a chamber for accommodating a bonding object, a vacuum part for making the chamber into a vacuum state, a plasma generator disposed outside the chamber, and a plasma gas formed through the plasma generator. A diffusion bonding device using external plasma can be provided, including a plasma inducing part that guides the plasma to enter the chamber, a heating part disposed in the chamber and heating the joint of the bonding object, and a pressurizing part that pressurizes 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 device and method, and in particular, to effectively remove or bond contaminants formed on the surface of the bonding object by placing a plasma generator outside and injecting the plasma gas generated therefrom into the chamber for diffusion bonding. It relates to a diffusion bonding device and method that can form a bonding layer that can strengthen.

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

These solid-state bonding technologies include friction bonding using frictional heat, brazing using inserted metal, and diffusion bonding using the diffusion phenomenon of atoms. Among these, diffusion bonding is a method of joining in a solid state by applying pressure to a degree that does not cause significant plastic deformation of the joined materials at a high temperature that does not melt the bonded materials.

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

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

While this conventional diffusion bonding requires a temperature of 600 to 1,000°C depending on the material, the hydrogen reduction reaction is a reaction that requires a higher temperature of 800 to 1,300°C and takes a long time, so it is difficult to completely remove the oxide film in the actual process. impossible. Therefore, for diffusion bonding at a given time, the principle of contact between pure metal surfaces is used while applying high pressure to destroy the oxide film while the oxide film is not completely removed.

In other words, more than the pressure and temperature required for bonding pure metal surfaces without an oxide film are required, and the degree of excess depends on the thickness of the oxide film, including appropriate pressure, heating temperature, and time. In addition, accurately measuring the thickness of the oxide film created by oxygen or moisture in the atmosphere is a highly difficult technology that requires expensive equipment, so there is a problem in working in the field without accurately determining the thickness of the oxide layer. Therefore, there were many problems, such as the degree of bonding or bonding strength of products shipped after completion of the process varied each time, causing serious bonding defects in some products.

To solve this problem, there is a recent prior art of equipping a plasma processing device within a reaction chamber, but for this purpose, the structure inside the chamber becomes complicated to form plasma inside, and control is difficult.

In addition, as the entire object to be joined is etched by the plasma generated inside the chamber, there is a problem that the object to be joined is damaged and the etching efficiency is reduced.

Republic of Korea Patent No. 10-2037368

The present invention provides a diffusion bonding device and method that can effectively remove the contaminant layer on the surface of the joint in diffusion bonding of solid objects and can also efficiently form a bonding layer that can strengthen the bond between the bonding parts of the bonded objects. The purpose is to

In order to achieve the above object, the present invention includes a chamber for accommodating a bonding object, a vacuum part for making the chamber into a vacuum state, a plasma generator disposed outside the chamber, and a plasma gas formed through the plasma generator. A diffusion bonding device using external plasma can be provided, including a plasma inducing part that guides the plasma to enter the chamber, a heating part disposed in the chamber and heating the joint of the bonding object, and a pressurizing part that pressurizes the bonding object.

Additionally, in the diffusion bonding device using external plasma according to the present invention, the heating source of the heating unit may be any one of an IR heater, a halogen heater, or a laser capable of locally heating the joint of the bonding object.

Additionally, in the diffusion bonding device using external plasma according to the present invention, the plasma gas may be an etching gas for removing a contamination layer formed on the surface of the joint of the bonding object.

Additionally, in the diffusion bonding device using external plasma according to the present invention, the plasma gas may be a gas for atomic layer deposition for forming a bonding layer for strengthening bonding on the surface of the bonding object.

Meanwhile, in order to achieve the above object, the diffusion bonding method provided by the present invention includes the steps of placing a bonding object in a chamber, a vacuum step of making the chamber into a vacuum state, and heating the joint of the bonding object. A first plasma injection step of generating a first plasma gas to remove a contamination layer formed on the surface of the joint outside the chamber and injecting the first plasma gas into the chamber, the injected first plasma gas It may include a contamination layer removal step of removing the contamination layer and a diffusion bonding step of joining the bonding objects by pressing the heated joints from which the contamination layer has been 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 gas in a plasma state.

Another diffusion bonding method using external plasma that can be provided by the present invention includes the steps of placing a bonding object in a chamber, a vacuum step of making the chamber into a vacuum state, a heating step of heating the joint of the bonding object, and the chamber. A second plasma injection step of generating a second plasma gas to form a bonding layer for strengthening the bond on the surface of the joint of the bonding object from the outside and injecting the second plasma gas into the chamber, the injected second plasma gas It may include a bonding layer deposition step of forming the bonding layer through plasma gas, and a diffusion bonding step of bonding the bonding objects by pressing the heated joints on which the bonding layer is formed.

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 , BCl3, AsH ₃ , PH ₃ , TeH ₂ , SnCl ₄ , GeCl ₄ , It may be a plasma 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, the first plasma gas is generated to remove a contamination layer formed on the surface of the joint outside the chamber and the first plasma gas is injected into the chamber. It may further include a contamination layer removal step of removing a contamination layer formed on the surface of the joint of the bonding object through the injected first plasma gas.

Through the diffusion bonding device 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.

Hereinafter, in describing the present invention, if a detailed description of a related known function or configuration is judged to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, when a part is said to 'include' a certain component, this does not mean that other components are excluded, but that it can further include other components, unless specifically stated to the contrary.

The diffusion bonding device using external plasma according to the present invention includes a chamber for accommodating a bonding object, a vacuum part for making the chamber into a vacuum state, a plasma generator disposed outside the chamber, and a plasma gas formed through the plasma generator. It may include a plasma inducing part that induces the plasma to enter the inside of the chamber, a heating part disposed in the chamber and heating a joint of the bonding object, and a pressurizing part that pressurizes the bonding object.

Diffusion bonding is a technology that uses diffusion of atoms that occurs between bonding surfaces in a solid state by heating and applying pressure to the joints of the objects to be bonded. In stages, plastic deformation similar to high-temperature creep deformation occurs by heating and pressurization, voids existing in the material are sphericalized to reduce interfacial energy, and voids are reduced by grain boundary diffusion and surface diffusion, and grain boundary movement. This happens actively, and the stages of disappearance of the public through diffusion occur one after another. In the final pore extinction stage, grain growth or recrystallization often occurs.

In this type of diffusion bonding, the surfaces of the joint are in direct contact and bonding is accomplished by diffusion, so it is very important to control the surface to be bonded. The joint surface is prone to the formation of a film due to oxidation or contamination due to contaminants during the process. The contamination layer formed by such an oxide film or contamination film is destroyed in the plastic deformation step and is finely dispersed or contained in solid solution inside the joining object. In order to destroy this contaminated layer, the temperature needs to be raised to a higher temperature than that required for plastic deformation, and quality problems such as lowered joint strength are likely to occur due to the material of the contaminated layer dissolved or dispersed inside.

In the present invention, a plasma generator is disposed outside the chamber to remove the contamination layer formed on the surface of the joint or to add a bonding layer to strengthen the bond strength on the surface of the joint, and a diffusion bonding device using remote plasma is used. can be provided.

First of all, removal of the contamination layer on the joint surface is a very important factor in surface control. The contamination layer refers to a film layer containing impurities other than the pure joining object, such as an oxide film or a contamination film, formed on the surface of the joint surface. In particular, when the object to be joined is a semi-metallic material such as nitride, carbide, metal, or 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 the surface not only makes diffusion bonding difficult, but also weakens the strength of the joint due to oxides mixed into the joint after diffusion bonding. Therefore, removing this oxide film before diffusion bonding is a very important issue.

In the present invention, the oxide film can be removed through plasma gas. After the object to be bonded is placed inside the chamber, the contamination layer is removed by the plasma gas injected into the chamber just before bonding, so after removing the contamination layer and before bonding. There is no need to worry about the surface being contaminated again by oxidation or the like.

Additionally, in the present invention, the generation of plasma gas and injection into the chamber are performed through a remote plasma system in which plasma gas generated outside the diffusion bonding device is guided into the chamber. Through this, there is no need to provide a complicated plasma forming device inside the chamber, making the diffusion bonding device simple and easy to control, 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 joining through diffusion between objects to be joined without using other insertion materials, but when a bonding layer that allows for smoother bonding is formed between objects to be bonded, bonding strength can be increased. Therefore, the plasma gas injected into the chamber in the diffusion bonding device according to the present invention may be an atomic layer deposition gas that can be deposited as a thin bond material on the surface of the joint.

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

The atomic layer deposition gas for this bonding layer can deposit a material different from the bonding object, or deposits a material containing the same element as the element contained in the bonding object, such as silicon or silica, on the surface of the quartz bonding object. It may be gas for

Meanwhile, in the diffusion bonding device according to the present invention, the heating unit that heats the joint of the bonding object may be an IR heater, a halogen heater, or a laser that can locally heat the joint.

Diffusion bonding requires heating of the bonding object. 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 joint or the deposition of the joint material can be smoothly performed. However, when the entire object to be joined is heated, etching or deposition can occur not only on the surface of the joint but also in other parts. Therefore, it is desirable that heating occurs only on the surface of the joint as much as possible.

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

A schematic diagram of one embodiment of the diffusion bonding device according to the present invention is shown in Figure 1. As a diffusion bonding device for bonding a bonding object 70, a plasma generator 30 is disposed outside the chamber 10, and the plasma gas generated therefrom is directed into the chamber 10 through the plasma guide 40. is injected. The bonding object 70 is disposed between the pressing portions 60 for pressing, and the heating portion 50 for locally heating the bonding portion of the bonding object 70 is disposed toward the bonding object 70. These heating units can be UV lamps, halogen lamps, or lasers. A vacuum device 20 may also be placed outside the chamber 10 to maintain a vacuum in the chamber.

The diffusion bonding method using an external plasma device according to the present invention includes the steps of placing a bonding object in a chamber, a vacuum step of making the chamber into a vacuum state, a heating step of heating the joint of the bonding object, and the bonding object outside the chamber. A first plasma gas injection step of generating a first plasma gas to remove a contamination layer formed on the surface of the joint of the bonding object and injecting the first plasma gas into the chamber, through the injected first plasma gas It may include a contamination layer removal step of removing the contamination layer and a diffusion bonding step of joining the bonding objects by pressing the heated joints from which the contamination layer has been removed.

The first plasma gas is an etching gas and can remove a contamination layer formed on the surface of the joint. By pressurizing the bonded object after removing the 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 a plasma 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 , O2 and H ₂ It may be a state gas. By containing fluorine or using oxygen or hydrogen, it is possible to effectively remove the oxide film formed on the surface of semimetals such as carbides, nitrides, metals, or silicon.

For example, the bonding object 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. By applying the diffusion bonding method to assemble the SiC focus ring, the oxide film formed on the SiC surface is effectively removed using external plasma within the chamber before diffusion bonding, thereby making it possible to manufacture a focus ring with strong bonding force.

Additionally, 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. By forming a bonding layer for strengthening the bond on the surface of the joint of the bonded object using this plasma gas for deposition, the bond strength after bonding can be improved.

The plasma gas for this 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 , and MoF ₆ may be a gas in a plasma state generated from one or more types of gas selected from the group consisting of

On the other hand, 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 bonding area can be removed in advance through generating and injecting plasma for etching before the deposition plasma injection step for forming the bonding layer. You can.

Claims (9)

delete delete delete delete Placing a bonding object within the chamber;
A vacuum step to bring the chamber into a vacuum state;
A heating step of heating the joint of the joint object;
A first plasma gas injection step of generating a first plasma gas for removing a contamination layer formed on the surface of the joint outside the chamber and injecting the first plasma gas into the chamber;
a contamination layer removal step of removing the contamination layer through the injected first plasma gas;
A second plasma gas injection step of generating a second plasma gas for forming a bonding layer for strengthening the bond on the surface of the bonding part of the bonding object outside the chamber and injecting the second plasma gas into the chamber;
A bonding layer deposition step of forming the bonding layer using the injected second plasma gas; and
A diffusion bonding method using an external plasma, comprising: a diffusion bonding step of bonding the bonding objects by pressing the heated bonding layer-formed bonding portions to each other. According to claim 5,
The first plasma gas is a plasma 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 Diffusion bonding method using external plasma, which is a state gas. delete According to claim 5,
The second plasma gas 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 , a diffusion bonding method using an external plasma, which is a plasma gas generated from one or more gases selected from the group consisting of
delete

Images