KR100942944B1

KR100942944B1 - Method for Manufacturing of Multi-layer Thin film Substrate and the multi-layer Thin film Substrate

Info

Publication number: KR100942944B1
Application number: KR1020080018607A
Authority: KR
Inventors: 김상희
Original assignee: 주식회사 탑 엔지니어링
Priority date: 2008-02-28
Filing date: 2008-02-28
Publication date: 2010-02-22
Also published as: KR20090093211A

Abstract

A method for manufacturing a defense industry LTCC thin film multilayer substrate requiring high reliability using a TiO ₂ insulating film, the method comprising: (a) preparing a low temperature co-fired ceramic (LTCC) substrate body fired at 850 to 900 ° C., (b) Performing a mechanical polishing process on the LTCC substrate body, and then performing heat treatment, (c) forming an insulating film on both sides of the LTCC substrate body, and (d) forming a base metal film on both sides of the LTCC substrate body. And (e) forming a thin film conductive line on the base metal film, and (f) etching the base metal film to separate the thin film conductive line.

By using the above method, it is compatible with the existing LTCC thin film multilayer substrate manufacturing process, it is possible to manufacture a high reliability product.

LTCC, Polishing, Base Metal Film, Insulation Film

Description

Method for manufacturing multi-layer thin film substrate and its multi-layered thin film substrate {Method for Manufacturing of Multi-layer Thin film Substrate and the multi-layer Thin film Substrate}

The present invention relates to a method for manufacturing a low temperature co-fired ceramic (hereinafter referred to as low temperature co-fired ceramics (LTCC)) multilayer thin film substrate, and a multilayer thin film substrate thereof. In particular, for the defense industry that requires high reliability using a TiO ₂ insulating film An LTCC thin film multilayer substrate manufacturing method and its multilayer thin film substrate are provided.

Specifically, in the present invention, the LTCC multilayer substrate is formed of Ti metal, which is used in the thin film manufacturing process, to improve the chemical resistance characteristics in order to effectively manufacture the thin film conductive line which uses the conventional LTCC manufacturing process but requires chemical resistance and high reliability. to affinity producing the aerosol deposition (aerosol deposition) using the process by forming the TiO ₂ insulating TPC (Ti / Pd / Cu) base metal and the affinity superior LTCC thin film multi-layer substrate to effectively forming the high TiO ₂ insulating film and that It relates to a multilayer thin film substrate.

Recently, due to the development of mobile communication technology, electronic components used in the field of mobile communication technology are accelerating in miniaturization, complexation, modularization and high frequency. In order to satisfy this demand technology, the precision of the metal conductive line (wiring) is increasing.

Since the LTCC thin film multilayer board used in the conventional defense industry products directly forms a thin film on the LTCC multilayer board, Ag conduction wire, which is a via hole for LTCC terminals, and Ti / Pt / Cu / Ni / Au metal, which is a thin film conduction wire, Thin film conductive wires having the same characteristics are manufactured using vacuum deposition, photolithography, electroplating and wet etching process techniques.

Figure 1 shows a conventional multilayer thin film substrate manufacturing process diagram. As can be seen in Figure 1 LTCC multilayer substrate is made of a conventional general LTCC multilayer substrate, and formed a thin film pattern on the substrate.

The LTCC multilayer substrate uses a ceramic material capable of simultaneously firing a metal electrode implemented as a circuit at a low temperature of 850 to 900 ° C with silver (Ag) having excellent electrical conductivity. Most ceramic materials are glass components, and the firing temperature can be adjusted according to the addition amount.

The first characteristic of LTCC multilayer board is low loss. In other words, by using a ceramic material having a high Q value and a silver (Ag) conductor having excellent electrical conductivity characteristics, not only the amount of strategic use can be reduced, but also because of its high frequency characteristics, it is widely applied to manufacturing ultra high frequency components.

As a second feature, the metal wiring can be a three-dimensional stacked structure. In particular, passive components such as resistors, capacitors, and inductors can be embedded in the board, thereby miniaturizing and simplifying components due to high integration.

The third characteristic is that the thermal expansion coefficient of LTCC multilayer substrate is about 5 ppm / ℃, which is similar to the thermal expansion coefficient of Si wafer which is widely used in semiconductor device fabrication or GaAs substrate which is widely used in high frequency device fabrication. Have

In addition, the main material of the LTCC multilayer wiring board is glass-based ceramic, which is soluble in strong acids such as HF. Also, Ag, an interlayer connecting material, is bulk, and has higher electrical conductivity than a thinly deposited metal. In electroplating, cracks occur on the surface of the Ag conductor or the surface of the Ag conductor, or pin holes are formed around the Ag conductor, and thus there is a problem in adhesion and conductivity with the thin film conductor. 2 and 3 are photographs showing a defect phenomenon which is a problem in the conventional manufacturing process.

That is, FIG. 2 shows an example of a bond pad plating failure as an SEM photograph, and the plating failure was observed at the Ag conductive line / thin film conductive line. 3 illustrates pin holes in Ag conductive lines / thin film conductive lines as examples of other bond pad plating defects.

In order to solve the problems of the conventional method of manufacturing a multilayer thin film substrate as described above, the present invention is compatible with the manufacturing process of the existing LTCC thin film multilayer substrate using a TiO ₂ insulating film, the chemicals used to form a thin film conductive line The present invention provides a method for producing a thin film conductive line having excellent chemical resistance.

An object of the present invention is to solve the problems described above, LTCC thin film multilayer substrate manufacturing method which can effectively manufacture the high reliability and high integration required in the defense industry products by excellent adhesion between metals compared to the conventional method And the multilayer thin film substrate.

In order to achieve the above object, a method of manufacturing a multilayer thin film substrate according to the present invention comprises the steps of (a) providing a low temperature co-fired ceramic (LTCC) substrate body fired at 850 ~ 900 ℃, (b) a machine on the LTCC substrate body Performing a heat treatment after the conventional polishing process, (c) forming an insulating film on both sides of the LTCC substrate body, (d) forming a base metal film on both sides of the LTCC substrate body, and (e) Forming a thin film conductive line on the base metal film, and (f) etching the base metal film to separate the thin film conductive line.

In the method of manufacturing a multilayer thin film substrate according to the present invention, the step of forming a predetermined pattern on both sides of the LTCC substrate main body before the step (c) and the predetermined pattern and the predetermined pattern after the step (c) And removing the insulating film on the top to open the contact via.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the predetermined patterns formed on both surfaces are formed at the same time with a vertical developing device.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the base metal film is a metal film for connecting a via pattern and a thin film pattern of an LTCC substrate and forming a thin film wiring.

In the method of manufacturing a multilayer thin film substrate according to the present invention, the base metal film is a Ti metal layer deposited by a DC magnetron sputtering method to a thickness of 2000 kPa to 5000 kPa, and a Pd (palladium) metal layer on the Ti metal layer from 100 kPa to The film is formed at a thickness of 500 kPa, and finally, the Cu metal layer as the main conductive line is formed at a thickness of 2500 kPa to 10000 kPa.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the step (f) is performed by a wet etching method and a dry etching.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the dry etching is performed by using an ion milling equipment and a gas.

In the method for manufacturing a multilayer thin film substrate according to the present invention, wet etching is performed on the Cu metal layer, and dry etching is performed on the Pd metal layer and the Ti metal layer.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the insulating film is characterized in that the TiO ₂ .

In addition, in the method of manufacturing a multilayer thin film substrate according to the present invention, the insulating film is characterized in that it is formed by an aerosol deposition (Aerosol Deposition) method.

In addition, in the method for manufacturing a multilayer thin film substrate according to the present invention, the insulating film is characterized in that formed at a thickness of 5 ~ 15㎛ at room temperature.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the thin film conductive line is a composite metal, characterized in that composed of Cu, Ni and Au or Cu and Au.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the Cu is 10 to 25 µm as the main conductor, the Ni metal is 2 to 4 µm and the Au metal is formed to be less than 5 µm.

In the method for manufacturing a multilayer thin film substrate according to the present invention, the Cu is 10 to 25 µm as a main conductive line, and the Au metal layer is 5 µm to 10 µm.

In the method of manufacturing a multilayer thin film substrate according to the present invention, the heat treatment in the step (b) is characterized in that it is maintained at 600 ℃ for 6 hours.

Further, in the method for manufacturing a multilayer thin film substrate according to the present invention, the trace amount of the photosensitive agent residue remaining on the substrate in each of the above steps is removed by a descom in a vacuum O ₂ plasma gas state.

In addition, the multilayer thin film substrate according to the present invention is characterized in that the multilayer thin film substrate made by the above-described method for producing a multilayer thin film substrate.

As described above, the LTCC thin film multilayer substrate manufacturing method using the TiO ₂ insulating film proposed in the present invention is an innovative process technology, compatible with the existing LTCC thin film multilayer substrate manufacturing process, it is possible to obtain a high reliability product.

The above and other objects and novel features of the present invention will become more apparent from the description of the specification and the accompanying drawings.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention is demonstrated according to drawing.

4 is a view showing a process chart for manufacturing a multilayer thin film substrate according to the present invention.

Each process illustrated in FIG. 4 will be described with reference to FIGS. 5 to 18.

As shown in FIG. 5, in the present invention, an LTCC multilayer wiring board including N layers is provided (S10). The number of layers can vary depending on the substrate design and the like, and is generally composed of about 3 to 10 layers. At this time, the metal wiring metal used is mostly Ag and the composition can be changed if necessary. More than 60% to 70% of the ceramic material is glass and most of the remainder is composed of alumina (Al ₂ O ₃ ). The thickness of the substrate is varied according to the customer's requirements, usually about 0.7 ~ 2.0mm. In Fig. 5, Via 1 to Via n are via holes (through holes) formed on the substrate, respectively, and Signal line 1 to Signal line n respectively represent conductive lines formed on the substrate.

LTCC multilayer wiring board is manufactured by printing wiring on each of N green sheets, stacking all layers, and simultaneously sintering at about 850 ~ 900 ℃. The surface of the substrate is separated from glass and alumina. The surface is rough. In order to form the thin film pattern, since the substrate surface roughness is about 1 μm or less, a mechanical polishing process is performed (S20). In designing the substrate, the substrate is formed thicker than the polishing thickness in consideration of the warpage of the substrate, and then the polishing is performed. Usually, polishing is carried out at about 50 to 100 µm.

The LTCC multilayer substrate on the polishing substrate may be contaminated with organic and inorganic substances during polishing, and the binder component remains in the LTCC multilayer substrate, so that carbon gas may be generated in the high temperature heat treatment process. This carbon gas component may affect the TiO ₂ insulating film properties and thus affect adhesion. Therefore, the process of heat treatment at high temperature for a long time is very important. The operating conditions are maintained at 600 ° C. for 6 hours to perform a heat treatment process to completely remove the carbon component remaining in the LTCC substrate (S30).

Thereafter, surface cleaning is performed to form a TiO ₂ insulating film on the polishing substrate, and then, PR is laminated on both sides of the substrate using a dry photoresist (Photoresistor (PR: photoresist)) using a laminator (S40). ). At this time, the pressure, temperature and speed of the laminator must be adjusted well to remove the pores. If pores occur in the PR, they must be reworked. It is important to make the PR as thick as possible. Generally 120 micrometers or more are used.

The process shown in FIG. 6 is a UV exposure process 1, in order to form a pattern by irradiating light of a photosensitive agent. Mask1 is a process of designing a mask 1 pattern so as to polymerize the light-receiving part and photosensitive the photosensitive agent using a dual exposure device (S50). Important variables here are the power of the UV light source and the exposure time. If the power of the light source is strong and the exposure time is long, it becomes under-develop and a larger pattern is formed than the desired pattern.If the UV light source is weak and the exposure time is short, it becomes over-develop. A pattern smaller than the desired pattern is formed.

The process illustrated in FIG. 7 is a development 1 process. Since the pattern 1 of both surfaces of the photosensitive agent is formed at the same time, a vertical type developer is used (S60). By spraying the developing solution through the nozzle on both surfaces of the substrate, the accurate pattern 1 can be obtained in a shorter time. Important variables here are the concentration of developer KOH, the temperature, the pressure of the injection being sprayed and the belt speed of the conveyor. If the variables of concentration, temperature, pressure and speed of the solution are not well controlled, it is difficult to obtain an accurate pattern. In this case, the concentration is generally about 1%.

Subsequently, if the scum of the photoresist remains on the developed substrate in the process of developing the Descum 1 process, it is difficult to form an insulating film on the surface of the substrate. The plasma (Plasma) equipment is used to perform the decompression in a vacuum O ₂ plasma gas state. Important variables in the process are plasma power, O ₂ gas flow rate and cleaning duration. If the cleaning time is long, be careful because PR is called a lot. Here, the discom refers to an operation of additionally removing a small amount of photoresist residue remaining after the developing operation is not removed.

Next, the step of forming the insulating film 2 on both surfaces of the LTCC multilayer wiring board shown in Fig. 8 is a very important step (S70). The LTCC substrate contains a large amount of voids, and the chemical resistance is bad because the surface of the substrate is composed of a glass component. In order to compensate for these disadvantages, a TiO ₂ oxide film having excellent insulation and affinity with Ti metal is formed on the surface of the LTCC substrate. The oxide film is formed by a chemical coating method, a chemical vapor deposition (CVD) method, a plasma sputtering method, or a physical vapor deposition method (PVD) method. However, this method requires high temperature treatment, so that the PR is deformed. Therefore, in the present invention, the film is formed by an aerosol deposition method that can be formed at room temperature. The thickness of this oxide film is 5-15 micrometers, Preferably it is about 10 micrometers. 15 shows a state where a TiO ₂ oxide film is formed as the insulating film by this S70 process.

Next, the process shown in FIG. 9 is a PR removal 1 process of removing the insulating film 2 on the via pattern and PR as a photoresist for contact via openings (S80). The insulating film 2 is removed by mechanical scrubbing and then removed using a PR strip device. The PR strip can be easily removed by well controlling the concentration of the stripper solution and the nozzle pressure in the PR strip, and by simultaneously supplying ultrasonic waves. At this time, the control of the ultrasonic power is very important. It is very important to remove the moisture remaining on the substrate before depositing the base metal. Therefore, a process of sufficiently drying the substrate at a high temperature before deposition of the base metal is included. The state in which this S80 process was completed is shown in FIG.

The process illustrated in FIG. 10 is a process for depositing the base metal 4 for connecting the via pattern and the thin film pattern of the LTCC substrate and forming the thin film wiring (S90). That is, in order to promote the adhesion between the thin film wiring and the surface of the LTCC substrate, a Ti metal layer having excellent adhesion to the ceramic surface is deposited at a thickness of 2000 kV to 5000 kPa, preferably 3000 kPa by a DC magnetron sputtering method, and the Cu interlayer directly on the Ti metal layer. A Pd (palladium) metal layer serving as a barrier of 100 to 500 kPa, preferably about 200 kPa is formed, and a Cu metal layer, which is a main conductive line, is formed to form a base metal layer by 2500 to 10000 kPa, preferably 9000 kPa or more. It is a process to do it. In this case, when the Cu metal layer is formed to be less than 2500 GPa, a Cu protrusion occurs during electroplating. Therefore, the Cu metal layer must be formed to be 5000 GPa or more. However, in order to obtain stable plating thickness, it is very advantageous to deposit about 10000 kPa. In addition, the Ar (argon) gas pre-sputtering process implementation before the base metal 4 is deposited affects the adhesion between the substrate and the metal and the ohmic contact between the contact vias.

Thereafter, a PR lamination 2 process of coating a photoresist for forming a thin film conductive line on both surfaces of the substrate is performed (S100). The photoresist used in this case uses a different type of PR than the lamination 1 process. This is because the pattern used at this time is a fine pattern of 100 μm or less and a negative photoresist having a thickness of 30 μm or less. Therefore, the laminator equipment is used separately or working conditions are followed. The parameters of the job are the same as for lamination 1, but the job conditions are different.

Since the process illustrated in FIG. 11 uses a negative photosensitive agent 5 in dry form, a mask pattern different from Mask 1 is used (S110). The working variable is the same as the UV exposure 1 condition, but the working condition has a different value because the PR thickness is relatively thin. Optimum working conditions are required to form fine patterns.

Next, the development process of the photosensitive agent of PR2 is performed (S120). The developer equipment can use the same equipment and the working conditions are different. Optimum conditions are necessary to form the fine pattern.

The PR descum 2 process then removes the remaining PR debris on the substrate surface, which typically uses gas plasma. At this time, since the base metal of the substrate is Cu, a gas mixed with Ar and O ₂ is generally used to prevent oxidation. The parameters of the work are the same as for the DISCOM 1 process, although the gas and conditions differ from the DISCOM 1 process, but the equipment can be used in common.

The thin film conductive line 6 forming process shown in FIG. 12 is a plating process of forming a thick metal film by an electroplating method to thicken the metal wiring film in order to reduce the electrical conductivity of the thin film wiring and the electrical resistance of the high frequency line (S130). At this time, the thin film conductive line 6 is composed of Cu, Ni, and Au as a composite metal. Cu is usually 10 to 25 µm as the main conductive wire, 2 to 4 µm for the Ni metal, and less than 5 µm for the Au metal. Metal thickness may vary depending on the application. At this time, the Ni metal may be selectively removed. This is because the Ni metal may be removed when the Au metal layer is 5 μm or more, preferably 5 μm to 10 μm to prevent diffusion of the interface between the Cu layer and the Au layer.

The process shown in FIG. 13 is a PR removal 2 process of removing PR as a photosensitive agent (S140). It is a process that is removed by using a general PR strip equipment. The PR can be easily removed by controlling the concentration of the stripper solution and the nozzle pressure at the time of PR strip and simultaneously supplying ultrasonic waves. At this time, the control of the ultrasonic power is very important .

Thereafter, as illustrated in FIG. 14, the conductive line is separated by etching three metal films sputtered with the base metal for electroplating (S150). This is because the base metal is thinly coated on the entire surface of the substrate, and if it is left as it is, the conductive wires are short-circuited, thereby removing unnecessary metal films. There are two ways to remove the base metal film. That is, a wet etching method using a chemical solution, a dry etching method using ion milling equipment, and a gas.

In the present invention, etching is performed by applying both methods. The relatively thick Cu metal etched the Cu metal layer by a wet etching method with a fast etching rate, and the relatively thin Pd and Ti metal by using a dry etching method to produce an excellent LTCC thin film multilayer substrate. The state in which this S150 process is completed is shown in FIG. FIG. 18 illustrates a state in which the Au wire bonding process is performed on a product having such a process.

In addition, if necessary, after the S150 process, a descom process may be performed to remove debris.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

1 is a view showing a conventional multilayer thin film substrate manufacturing process diagram,

2 and 3 is a photograph showing a bad phenomenon that is a problem appearing in the conventional manufacturing process,

4 is a view showing a process chart for manufacturing a multilayer thin film substrate according to the present invention;

5-14 show each process shown in FIG. 4;

15 is a photograph showing a state in which a TiO ₂ oxide film is formed as an insulating film by the S70 process shown in FIG. 4;

16 is a photograph showing a state in which the S80 process illustrated in FIG. 4 is completed;

17 is a photograph showing a state in which the S150 process illustrated in FIG. 4 is executed;

18 is a photograph showing a state in which the Au wire bonding step is performed in the state shown in FIG. 17.

Claims

(a) preparing a low temperature co-fired ceramic (LTCC) substrate body fired at 850-900 ° C.,

(b) performing a mechanical polishing process on the LTCC substrate body and then performing heat treatment;

(c) forming insulating films on both surfaces of the LTCC substrate body;

(d) forming a base metal film on both sides of the LTCC substrate body,

(e) forming a thin film conductive line on the base metal film,

(f) etching the base metal film to separate the thin film conductive lines.

The method of claim 1,

Forming a predetermined pattern on both surfaces of the LTCC substrate body before the step (c);

And removing the predetermined pattern and the insulating layer on the predetermined pattern after the step (c) to open the contact via.

The method of claim 2,

The predetermined pattern formed on both surfaces is formed at the same time with a vertical developing device.

The method of claim 1,

The base metal film is a metal film for connecting the via pattern and the thin film pattern of the LTCC substrate to form a thin film wiring, characterized in that the manufacturing method of the multilayer thin film substrate.

The method of claim 4, wherein

The base metal film is a Ti metal layer deposited by a DC magnetron sputtering method to a thickness of 2000 kPa to 5000 kPa, a Pd (palladium) metal layer is formed on the Ti metal layer to a thickness of 100 kPa to 500 kPa, and finally Cu metal layer as the main conductive line To form a film having a thickness of 2500 kPa to 10000 kPa.

The method of claim 5,

The step (f) is a method for producing a multilayer thin film substrate, characterized in that the wet etching method and dry etching.

The method of claim 6,

The dry etching is performed by using an ion milling equipment and a gas.

The method of claim 7, wherein

The wet etching is performed with respect to the said Cu metal layer, and the dry etching is performed with respect to the said Pd metal layer and a Ti metal layer.

The method of claim 8,

The insulating film is a method of manufacturing a multilayer thin film substrate, characterized in that made of TiO ₂ .

The method of claim 9,

The insulating film is a method of manufacturing a multilayer thin film substrate, characterized in that formed by aerosol deposition (Aerosol Deposition) method.

The method of claim 10,

The insulating film is a method of manufacturing a multilayer thin film substrate, characterized in that formed at a thickness of 5 ~ 15㎛ at room temperature.

The method of claim 1,

The thin film conductive line is a composite metal, Cu, Ni and Au or Cu and Au, characterized in that the manufacturing method of the multilayer thin film substrate.

The method of claim 12,

The Cu is 10 to 25㎛ as the main conductive line, Ni metal is 2 to 4㎛ and Au metal is deposited to less than 5㎛ method of producing a multilayer thin film substrate.

The method of claim 12,

Cu is 10 to 25 µm as the main conductive line, and the Au metal layer is 5 µm to 10 µm.

The method of claim 12,

In the step (b), the heat treatment is maintained for 6 hours at 600 ℃ manufacturing method of a multilayer thin film substrate.

The method of claim 12,

The trace amount of photoresist residue remaining on the substrate in each step is removed by a discom in a vacuum O ₂ plasma gas state.

A low temperature co-fired ceramic multilayer substrate formed by stacking a metal wiring metal layer and a ceramic layer, the metal wiring metal layers being connected to each other by filling via holes formed in the ceramic layer;

A TiO 2 insulating film (2) formed on both surfaces of the low temperature cofired ceramic multilayer substrate;

A base metal (4) passing through the TiO2 insulating film (2) and simultaneously connected to the metallization metal layer and the ceramic layer filled in the via hole and simultaneously deposited on the TiO2 insulating film (2); And

A thin film conductive line 6 formed on the base metal 4,

The base metal (4) is a multi-layer thin film substrate, characterized in that the Ti metal layer, Pd metal layer, Cu metal layer is sequentially stacked from the TiO ₂ insulating film (2) to the thin film conductive line (6).