WO2007119905A1

WO2007119905A1 - Technique of metal thin film deposition on the polymeric matrix

Info

Publication number: WO2007119905A1
Application number: PCT/KR2006/002596
Authority: WO
Inventors: Jong Han Song; Won Kook Choi
Original assignee: Korea Institute Of Science And Technology
Priority date: 2006-04-13
Filing date: 2006-07-03
Publication date: 2007-10-25
Also published as: KR20070102066A; KR100802986B1

Abstract

Disclosed therein is a method of depositing a metal thin film on a polymeric matrix, in which surface cleaning of the polymeric matrix through a high flux metal ion irradiation process generating a beam energy of several to several hundred keV, surface modification of the polymeric matrix by energy transfer of ion beams, formation of an active layer having an excellent chemical affinity between interface atoms by metal ion injection, etc., are advantageously achieved prior to deposition of the metal thin film, and the metal thin film is formed on the polymeric matrix through a successive batch deposition process, thereby improving interface adhesion between the polymeric matrix and the metal thin film deposited, as well as promoting simplicity of the process due to unnecessity to perform separate chemical pre-cleaning processes.

Description

Description TECHNIQUE OF METAL THIN FILM DEPOSITION ON THE

POLYMERIC MATRIX

[i]

Technical Field

[2]

[3] The present invention relates to a method of depositing a metal thin film on a polymeric matrix, and more particularly to a method of depositing a metal thin film on a polymeric matrix in which the polymeric matrix is subjected to a high flux ion irradiation process in an energy range of several to several hundred keV prior to deposition of the metal thin film, thereby improving interface adhesion between the polymeric matrix and the metal thin film deposited.

[4]

Background Art

[5]

[6] In general, when a metal thin film is formed on a polymer substrate such as polycarbonate widely used in mobile communication terminals, an adhesion is very poor, and as shown in FIG. 5, a chemical pre-cleaning process (UV curing, surface preparation, etc.) is necessarily required. Thus, the regulation against the use of chemicals is reinforced both in developed countries and Korea due to serious environmental pollution as well as bodily contamination of persons engaged in such work.

[7] In advanced countries, the regulation on Volatile Organic Compound (VOC) related to carcinogenicity, Venenosity, and the intermixing of toxic gases has been enforced. The European Unions (EU) and China plan to enforce the regulation against toxic and harmful substances as of July 1, 2006 pursuant to EU's guidelines on Waste Electrical and Electronic Equipment (WEEE) and on Restriction of Hazardous Substances (ROHS), and China Compulsory Certification (CCC) guideline, respectively.

[8] The purpose of these guidelines is to eliminate any existing differences among the laws of each respective country in restricting the use of certain hazardous substances in electrical and electronic equipments as well as to contribute to protect the health of mankind and reduction in environmental load of WEEE.

[9] Accordingly, the use of six harmful substances used in wet and dry plating processes, i.e., hexavalent chromium, cadmium, mercury, lead, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) in electrical and electronic equipment, is expected to be regulated, and there is an urgent need to develop an environment- friendly cleaning process.

[10] The conventional method for improving adhesion between a metal thin film and a substrate is as follows.

[11] First, the wet plating process includes a method of an ion etching pre-treatment of the substrate prior to deposition or concurrently with deposition using an inert gas whereas the dry plating process includes a method in which a surface active layer is formed using an organic substance to thereby improve interface adhesion between the interface and the based material or functionalized radical is formed between the interface and the based material through a surface acid treatment.

[12] Another method for improving adhesion between a metal thin film and a substrate includes a method in which a gas ion with an energy of several to several hundred keV is irradiated onto a substrate to increase the roughness of the substrate's surface to thereby increase the adhesion area on the substrate; a chemical functional group is formed on the substrate's surface using reactive gases to thereby induce a chemical reaction with the metal thin film; or a dense thin film is fabricated using an energy of a gas ion-assisted layer to thereby improve the interface adhesion.

[13] In addition to these methods, an ion beam mixing method or a method is used in which a buffer-adhesion promoter is formed between the metal thin film and the matrix to thereby improve adhesion therebetween.

[14] As such, a conventional physical deposition method of depositing a metal thin film on a polycarbonate substrate raises problems that it cannot provide a satisfiable level of adhesion, and also in case of the wet process, the deposition of the metal thin film is only made possible after pre-treatment of a primer (organic paint).

[15] Moreover, in case where an additive or a reinforcing agent of several tens of percents (%) or more is added to the matrix in order to improve the mechanical and chemical properties of polymers, chemical cleaning work is difficult and the formation of the metal thin film is impossible if a chemically modified surface layer is not formed.

[16] Further, the formation of the metal thin film is also difficult even in a fiber reinforced plastic (FRP) and an ultra violet (UV) paint layer.

[17] In the meantime, the Japanese Patent Laid-Open Publication No. Hei 6-311392 discloses a technique in which polycrystal layers with crystallinity are formed at low temperature in thin film transistors used in solar cells or liquid crystal panels via metal ion irradiation prior to thin-film deposition such as vacuum deposition, electron-beam deposition (EBD), etc. According to the above technique, a good crystalline thin film is formed on the TFT substrate only by means of a low-temperature process of relatively low temperature, i.e., an epitaxy temperature. In other words, excellent crystalline nuclei are formed at a relatively low temperature of below 300 ⁰C without maintaining the substrate at high temperature.

[18] However, such a technique requires formation of crystal layers at a temperature of below 300 ⁰C , which does not prevent atoms constituting a thin film from being diffused onto the substrate by a high temperature process. Also, problems may be raised in the case where a sharp interface is required or an ultra-thin film and the like are fabricated.

[19] In addition, the cost to perform the above process is very high because a metal ion irradiating apparatus used in the above case uses various units such as a tip electrode ion source, a decelerator for irradiating ions of low energy that does not damage the substrate, a focusing lens, an ion discriminator, a magnetic-field mass analyzer, etc.

[20]

Disclosure of Invention

Technical- Problem

[21]

[22] The present invention has been made to solve the above problems occurring in the prior art, and it is an object of the present invention to provide a method of depositing a metal thin film on a polymeric matrix, in which surface cleaning of the polymeric matrix through a high flux metal ion irradiation process generating a beam energy of several to several hundred keV while being applied with a high voltage, surface modification of the polymeric matrix by energy transfer of ion beams, formation of an active layer having an excellent chemical affinity between interface atoms by metal ion injection, etc., are advantageously achieved prior to deposition of the metal thin film, and the metal thin film is formed on the polymeric matrix through a successive batch deposition process, thereby improving interface adhesion between the polymeric matrix and the metal thin film deposited, as well as promoting simplicity of the process since it is not necessary to perform a separate chemical pre-cleaning process.

[23]

Technical- Solution

[24]

[25] To accomplish the above objective, according to a feature of the present invention, there is provided a method of depositing a metal thin film on a polymeric matrix, comprising:

[26] irradiating metal ions which are generated from a high flux metal ion source onto the polymeric matrix so as to clean the surface of the polymeric matrix, the metal ions having a beam energy of several to several hundred keV while being applied with a high voltage;

[27] modifying the surface of the polymeric matrix by a carbonization effect of the polymeric matrix surface through the elastic scattering between the irradiated metal ions and the polymer atoms of the polymeric matrix; [28] forming a metal ion implantation layer on the modified surface of the polymeric matrix through continuous irradiation of the metal ions;

[29] and depositing a metal thin film on the metal ion implantation layer.

[30]

Advantageous Effects [31] [32] According to the deposition method of a metal thin film on a polymeric matrix of the present invention, the polymeric matrix is subjected to a high flux ion irradiation process in an energy range of several to several hundred keV prior to deposition of the metal thin film, thereby improving interface adhesion between the polymeric matrix and the metal thin film deposited. [33] Further, the entire process can be shortened since it is not necessary to perform a separate pre-treatment process, as well as the metal ion irradiating apparatus performing the irradiation of the high flux metal ions can be constructed at a low cost due to its simplicity in construction. [34]

Description Of Drawings [35] [36] Other objects and advantages of the present invention can be better understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [37] FIG. 1 is a schematic view illustrating a metal ion irradiating apparatus used in a metal thin film deposition technique according to the present invention; [38] FIG. 2 is a process chart illustrating a metal thin film deposition process according to the present invention; [39] FIGs. 3 and 4 are photographs illustrating the results of adhesion test for a thin film sample obtained through a method of depositing a metal thin film on a polymeric matrix according to the present invention; [40] FIG. 5 is a process chart illustrating a metal thin film deposition process according to the prior art; and [41] FIG. 6 is a photograph illustrating a result of adhesion test for a thin film sample obtained through a conventional metal thin film deposition method according to the prior art. [42]

Best Mode [43]

[44] Reference will now be made in detail to the preferred embodiment of the present invention with reference to the accompanied drawings.

[45] FIG. 1 is a schematic view illustrating a metal ion irradiating apparatus used in a metal thin film deposition technique according to the present invention; FIG. 2 is a process chart illustrating a metal thin film deposition process according to the present invention; and FIGs. 3 and 4 are photographs illustrating a result of adhesion test for a thin film sample obtained through a method of depositing a metal thin film on a polymeric matrix according to the present invention.

[46] As shown in FIG. 1, a metal ion irradiating apparatus according to the present invention used in a metal thin film deposition technique includes a high vacuum chamber 12, a high flux metal ion source 10 disposed above the high vacuum chamber 12 and adapted to be applied with electric power from an ion source power supply 20. The flux metal ion source 10 is positioned on an insulation holder 11 for the purpose of high- voltage electric insulation of several to several hundred keV.

[47] Metal ions are drawn from the flux metal ion source 10 in a vacuum level of 5 x 10-

6

Torr, and metal ions having an energy of approximately 10 to 10OeV are irradiated o nnttoo aa ppoollyymmeric matrix in a dose range of 1 x 10 /cm to 1 x 10 /cm at room temperature.

[48] In this case, an initial vacuum level is less than 1 x 10 Torr, and the vacuum level is set to be less than 5 x 10 Torr so as to prevent the intermixing of undesired impurities and maintain the electric insulation of several to several tens of kV upon the drawing of the metal ions.

[49] The irradiation dose needed to optimally irradiate the metal ions depends on the kind of metal ions, energy and the properties of based materials. Thus, if the irradiation dose of the metal ions is beyond the preset dose range, the etching of metal ions irradiated or implanted unwantedly, and transformation, carbonization, warpage, shrinkage, cracking and so on of the polymeric matrix occur. Also, release or exfoliation phenomenon occurs on the surface of the polymeric matrix.

[50] Here, the metal ion source of a high flux is used because it can effectively shorten the process time.

[51] A high- voltage generator 21 is connected to the high flux metal ion source 10 to irradiate/implant the metal ions having an energy of several to several hundred keV generated from the high flux metal ion source 10 onto the surface of the polymeric matrix.

[52] In addition, to enable the uniform irradiation/implantation of the metal ions and the deposition of the metal thin film, a rotary drum 13 for attaching the polymeric matrix thereon is mounted to be rotated by a drive motor 14 for the rotary drum, and metal thin film depositing sources 15 and 16 are attached inside the high vacuum chamber 12.

[53] The comparison between the metal ion irradiating apparatus according to the present invention as constructed above and the above-mentioned conventional metal ion irradiating apparatus will be described in brief.

[54] The conventional metal ion irradiating apparatus is disadvantageous in terms of cost since it is high-priced equipment composed of a drawing electrode, a focusing lens, an accelerator, a magnetic-field mass analyzer, a deflector for removing neutral particles, and a beam scanner for the purpose of extraction and conveyance of the metal ions.

[55] The conventional metal ion irradiating apparatus as described above also includes a beam scanner for treatment of large area, but the inventive metal ion irradiating apparatus makes it easy to carry out the large area treatment since it uses a single ion source power supply 20 to concurrently operate a plurality of metal ion sources.

[56] Further, the metal ion irradiating apparatus according to the present invention enables the metal ions to be drawn from the high flux metal ion source 10, and simultaneously to be irradiated/implanted onto the polymeric matrix immediately even without implementing an existing accelerator needed for extraction and conveyance of high-purity metal ions of uniform energy. Also, the deposition of the large area is possible using the metal thin film depositing sources 15 and 16 within the high vacuum chamber 12 in a successive consequent process.

[57] The metal ion irradiating apparatus according to the present invention includes the rotary drum 13 mounted inside of the high vacuum chamber 12 corresponding to a target chamber of the conventional metal ion irradiating apparatus, so that the damage of the polymeric matrix can be prevented and uniform large area deposition can be performed according to a heating effect of the polymeric matrix by ion beams generated from the high flux metal ion source 10.

[58] In addition to the metal thin film, an oxide or a nitride (SiO , TiN, SiO, Al O , etc.) thin film may be deposited on the polymeric matrix, if necessary.

[59] The metal ions having a beam energy of several to several hundred keV generated from a high flux metal ion source 10 reach the polymeric matrix for mobile communication terminals, which contains polycarbonate, and then the polymeric matrix is initially subjected to a surface cleaning process to remove organic substances adsorbed on the surface of the polymeric matrix due to ion sputtering effect.

[60] At this time, the polymeric matrix is made of any one selected from the group consisting of polycarbonate, polyamide (PA), acrylonitrile-butadiene-styrene (ABS), Poly -methyl-methacrylate (PMMA), polyimde (PI), polystyrene (PS), modified polyphenylene oxide (MPPO), poly-oxy-methylene (POM), poly-ethylene (PE), UV paint, and a mixture comprising of more than several tens % of an additive or a reinforcing agent.

[61] After the surface cleaning of the polymeric matrix, in the process of transferring the beam energy of the metal ions to the polymeric matrix through the irradiation step of the metal ions having the beam energy of several to several hundred keV, a polymer chain is cut off by the elastic scattering between the irradiated metal ions and the polymer atoms of the polymeric matrix so that the polymeric matrix surface can be carbonized to modify the surface of the polymeric matrix.

[62] As such, as the irradiation dose of the metal ions increases gradually, a metal ion implantation layer is formed on the polymeric matrix whose surface is modified, and then a metal thin film is formed on the resulting metal ion implantation layer through any one process selected from continuous sputtering deposition and thermal deposition, or a combined process thereof.

[63] In this manner, when the metal thin film is deposited on the metal ion implantation layer after irradiation/implantation of the metal ions onto the polymeric matrix surface, the cleaning and surface-modification effects of the polymeric matrix by the ion irradiation, the interface adhesion between the polymeric matrix and the metal thin film deposited is reinforced by a chemical affinity or a bonding force between the metal atoms of the metal ion implantation layer and the atoms of the metal thin film.

[64] In addition, batch deposition process, a batch cleaning process maintaining vacuum can be applied by the use of equipment in which a high energy metal ion source and a metal thin film depositing source such as a sputter are combined together. Thus, the metal thin film deposition method according to the present invention enables to simplify the process using a connectivity technique between improvement over a conventional complex multi-staged process and the metal thin film deposition.

[65] Accordingly, as shown in FIG. 2, according to the process for the metal thin film deposition method of the present invention, the metal thin film with a relatively improved adhesion can be formed through a single process only even without performing separate pre-treatment processes (UV re-curing, washing, surface preparation, etc.) for the improvement of the adhesion of the metal thin film as compared to the process for the conventional metal thin film deposition method.

[66] Thus, the result of the properties of the metal thin film deposited after the surface of the polymeric matrix is cleaned by the metal ion irradiation/implantation technique using the high flux metal ion source according to the present invention was compared with that of the properties of the metal thin film formed by a conventional wet-type process.

[67] The following table 1 shows the evaluation result of the test for salt resistance, acid resistance, boiling water resistance, which exhibits relatively good results in all test items as compared to the test result of the conventional prior art.

[68]

Mode for Invention

[69] [70] [Example] [71] The present invention will be described hereinafter in detail using the following embodiments, but they should not be construed as limiting the scope of the present invention.

[72] [73] Example and comparative example [74] FIG. 3 is a photograph illustrating a thin film sample in which a metal thin film is deposited on a UV paint layer and then an UV paint layer as a protective layer is coated on the deposited metal thin film according to a preferred embodiment of the present invention, and FIG. 4 is a photograph illustrating a thin film sample in which a metal thin film is directly deposited on a polycarbonate layer free from a UV paint layer and then a UV paint layer as a protective layer is coated on the deposited metal thin film according to a preferred embodiment of the present invention, which further comprises a process of irradiating metal ions prior to the deposition of the metal thin film.

[75] On the other hand, FIG. 6 is a photograph illustrating a photograph illustrating a thin film sample in which a metal thin film is deposited on a UV paint layer and then an UV paint layer as a protective layer is coated on the deposited metal thin film.

[76] Here, as shown in FIGs. 3 and 6, formation of the UV coated base is intended to improve flatness of the surface of the metal thin film. [77] In this case, the test for adhesion of a thin film sample is carried out on the thin film sample in which horizontal and vertical lines are drawn at an interval of lmm on an area of lcm² . It can be seen from the above result of the adhesion test that the UV paint layer including the metal thin film of FIG. 6 is peeled off.

[78] Therefore, according to the present invention, the interface adhesion between the polymeric matrix and the metal thin film deposited is remarkably improved through improvement in chemical affinity between interface a toms by the irradiation of the high flux metal ions prior to the deposition of the metal thin film, as well as the entire process can be shortened since it is not necessary to perform separate pre-treatment processes.

[79] In the meantime, the present invention enables a variety of applications such as the external deposition using the metal thin film of mobile communication terminals with an antenna embedded therein in consideration of the transmission depth of the electromagnetic waves, as well as the internal and external deposition using metal thin films and oxides/nitrides.

[80]

Industrial Applicability

[81]

[82] As described above, according to the deposition method of a metal thin film on a polymeric matrix of the present invention, the polymeric matrix is subjected to a high flux ion irradiation process in an energy range of several to several hundred keV prior to deposition of the metal thin film, thereby improving interface adhesion between the polymeric matrix and the metal thin film deposited.

[83] Further, the entire process can be shortened since it does not require to perform separate pre-treatment processes, as well as the metal ion irradiating apparatus performing the irradiation of the high flux metal ions can be constructed at a relatively low cost since its construction is rather simple.

[84] While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.

Claims

[1] A method of depositing a metal thin film on a polymeric matrix, comprising:

(a) irradiating metal ions generated from a high flux metal ion source onto the polymeric matrix so as to clean the surface of the polymeric matrix, the metal ions having a beam energy of several to several hundred keV while being applied with a high voltage;

(b) modifying the surface of the polymeric matrix by a carbonization effect of the polymeric matrix surface through the elastic scattering between the irradiated metal ions and the polymer atoms of the polymeric matrix;

(c) forming a metal ion implantation layer on the modified surface of the polymeric matrix through continuous irradiation of the metal ions; and

(d) depositing a metal thin film on the metal ion implantation layer.

[2] The method as claimed in claim 1, wherein the metal ions are drawn from the flux metal ion source in a vacuum level of 5 x 10 Torr, and metal ions having an energy of approximately 10 to 10OeV are irradiated onto the polymeric matrix in a dose range of 1 x 10 /cm to 1 x 10 /cm at room temperature.

[3] The method as claimed in claim 1, wherein the polymeric matrix is made of any one selected from the group consisting of polycarbonate, polyamide, acry- lonitrile-butadiene-styrene, Poly -methyl-methacrylate, polyimde, polystyrene, modified polyphenylene oxide, poly-oxy-methylene, poly-ethylene, UV paint, and a mixture comprising of more than several tens % of an additive or a reinforcing agent.

[4] The method as claimed in claim 1, wherein the metal thin film is formed on the metal ion implantation layer through any one process selected from continuous sputtering deposition and thermal deposition, or a combined process thereof.

[5] The method as claimed in claim 1, wherein metals/non-metals, or oxides/nitrides are formed through the step of depositing the metal thin film on the metal ion implantation layer.