KR100343886B1 - Replication Method of Molybdenum metal-mould Stemper - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a replication technology of a metal mold stamper for replicating optical elements, such as diffractive optical elements, which require high resolution in the minute region of the nanometer region. The new metal mold stamper replication technology, which is environmentally friendly and has excellent mechanical properties, replaces the nickel electroplating method, which is a key process in the technology.

The molybdenum metal mold stamper duplication method of the present invention comprises the steps of loading a non-conductive mask pattern into the CVD chamber and checking the basic pressure to create a pressure atmosphere, and Ar2 as a carrier gas and H2 gas as a reaction gas in the CVD chamber. Supplying molybdenum gas as a source gas at the process pressure, and coating a molybdenum compound with a molybdenum metal on the mask pattern by chemical vapor deposition, and the mask; The molybdenum metal layer coated on the pattern is separated from the mask pattern, characterized in that the step of replicating the molybdenum metal mold stamper. Accordingly, it is possible to replicate the metal mold stamper of excellent mechanical properties, but also provides an environment-friendly replication technology.

Description

Replication Method of Molybdenum metal-mould Stemper}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a replication technology of a metal mold stamper for replicating optical elements, such as diffractive optical elements, which require high resolution in the minute region of the nanometer region. The new metal mold stamper replication technology, which is environmentally friendly and has excellent mechanical properties, replaces the nickel electroplating method, which is a key process in the technology.

In general, the micro-machining process in the nanometer region using a structure forming method (LIGA: Lithography, Galvanizing und Abformung) or silicon micromachining techniques.

The structure forming method called the LIGA method, which uses deep lithography using X-rays and makes a high aspect ratio microstructure by electroplating, generally requires a thickness (about 0.1 to 1.0 mm) for an X-ray photoresist layer such as PMMA. It is formed on a furnace substrate, and patterned using a heavy metal such as gold as an x-ray absorber and used as a mask. The resist is exposed by X-ray (SOR light) radiated from the synchrotron. Since X-ray SOR light has excellent linearity, resolution, and transmittance, it is possible to expose a thick resist with submicron precision or less. . After development, the structure of the resist is obtained. Subsequently, the whole is immersed in an electroplating solution, and nickel, copper, and gold are thickly stacked between the valleys of the resist structure by electroplating on the conductive substrate, and the metal is used as a mold to mold the plastic by injection molding. Also, based on the plastic mold made by injection molding, the metal structure is made again by electroplating or the ceramic powder is sintered into plastic to make the ceramic structure.

The LIGA method is characterized by the fact that the microstructure with large aspect ratio can be made of various materials, but there is a problem of how cheaply and easily the producer can use because it is difficult for general producers to use X-ray SOR light.

Silicon micromachining technology coats the silicon substrate on the silicon substrate, duplicates the mask pattern on the surface by developing and igniting the mask pattern, performs etching (etching) based on the duplicated pattern, and removes and removes unnecessary parts. As a technology for manufacturing a desired fine component by repeating the doping process, it is a technology proposed to add a technology for making a three-dimensional structure that was developed to produce a large amount of integrated circuits of semiconductor devices with high accuracy.

Although microstructures can be manufactured directly through structural formation methods and micromachining techniques, injection molding or hot embossing techniques are applied to mass production.

Unlike the conventional injection molding, fine injection molding requires precise mold processing and control technology, and the flow distance is long, and thus the process or material is restricted.

Hot embossing is easy to apply because of its simple process and simple control compared to fine injection molding.

In addition, a method of using a compression molding mold is known, but it is not suitable for molding a product for microforming, and thus a micro mold must be manufactured to create conditions suitable for microforming. The micro parts are thus sensitive to dust and fine cracks. There is a problem that it is easy to lose the commercial value by the post-treatment process.

Meanwhile, for the production of compact disks, digital video disks, and hologram lenses, records are stored on a glass wafer using photoresist and then mass-produced. The glass plate recorded for this purpose is duplicated with a metal to make a metal plate first, and the duplicated metal plate becomes a stamper.

The processing or molding of optical devices such as CD, DVD, LENS, etc. requires the technology of replicating or processing micro components in the area of several nanometers.

Cloning technology is a basic production technology for producing large quantities of products in one form. In particular, the diffraction optical device that requires high resolution in a very fine region of the nanometer region is treated as a core technology, and the stamper is manufactured by the nickel electroplating method.

An electroless nickel plating method is widely used as a nickel electroplating method applied to the manufacture of stampers. In this method, the deposition rate of the thin film is about 15 ~ 20㎛ / h, which takes a long time and the hardness is low, so the production quantity is only 5,000 ~ 50,000, and in many cases, it is nickel that corresponds to nickel shim during plating. Plated core inserts or stampers can cause deformation and cause many failures.

1 shows a process for manufacturing a metal mold stamper made of a metal plate for copying optical elements such as CD, DVD, LENS.

The stamper is mainly made by a process of master fabrication, metal electroforming, peeling and processing of an electroformed metal, as illustrated in FIG. 1, a master pattern manufacturing step (S10), Electroless plating, sputtering metal Lay (Metal Lay) forming step (S20), nickel plated electroplating (Electroplate Ni) forming step (S30), the master and the nickel core is produced through the separation step (S40).

Among them, the metal electroforming process is generally electroplated with nickel having good corrosion resistance.

At first, a nickel thin film of the same metal is formed by sputtering or electroless deposition in order to make an electrode for electroplating, and then a fast plating rate is achieved. It has a small residual stress in the plating layer and plated nickel to a thickness of about 0.2 ~ 0.5mm.

As such, the conventional method has two processes: electroless plating for electrode formation and electroplating for deposition thickness. Therefore, the process procedure is complicated and deformation occurs easily due to internal stress generated by different deposition methods, and wastewater treatment problem occurs due to the use of a plating solution.

Figure 2 schematically shows a replication method, showing the manufacturing procedure of the metal mold by electroplating.

In order to make an electrode for electroplating on the non-conductive mask pattern ((11) original microrelief), a nickel thin film, which is the same metal, may be electroless plated (12) using Ag spray or sputtering (13) using Au or Ag. Form. Regardless of the method, the plating rate is very slow.

Nickel is plated to a thickness of about 0.2 to 0.5 mm in the plating layer (14) metal layer of the mask pattern 11 by the electroplating method with a small residual stress.

Then, the mask pattern 11 and the plated metal mold 15 are separated.

The process sequence of the electroless plating method is shown in FIG. 3.

Degreasing and annealing process (S21) to prevent resin defects by treating contaminants, molding agents, and annealing processes (S21), and the surface is hydrophilized to enable catalytic treatment on the surface of degreased and annealed resin. Etching process (S22), a neutralization process (S23) to reduce chromium ions adhered to the resin surface by etching, so as not to adversely affect plating, and a catalyst for inducing adhesion of a noble metal catalyst to the hydrophilized resin surface Process activation 1 step (S24), activation 2 step (S25) corresponding to the final pretreatment process to allow electroless plating of the metal compound attached to the resin surface in a complete state, and to form a substantial metal coating on the activated resin surface. An electroless plating step (S26), an electrolytic (electro) plating step (S27), a drying (S28), a discoloration prevention treatment step (S29), and the like are sequentially performed.

Here, the electroplating (S27) is to conduct the object as a cathode in the electrolytic solution to precipitate the plated metal on the surface, there is a high possibility of staining after plating, depending on the shape, it is difficult to treat wastewater because it uses a highly toxic plating solution .

Therefore, the existing replication technology includes the nickel electroplating method as an important process, and has the following problems.

(1) Production costs are high due to many factors that raise costs by relying on chemicals to supply metal ions.

(2) Aging of the plating liquid is fast, and recycling of the used liquid is almost impossible.

(3) When discharged by using a basic acid as the plating solution, it is difficult to treat wastewater, such as increasing the chemical oxygen demand (COB) due to complex salts.

(4) Since it is a high temperature type, heating is required and energy consumption is high.

(5) Since the mask pattern on the non-conductor is plated, peeling is necessary, so the importance of equipment and material selection increases regardless of quality.

(6) It requires complicated pretreatment, and the life of the manufactured metal mold is relatively short.

Accordingly, an object of the present invention is the two processes of electroless plating and electroplating, which are core processes in the metal mold stamper replication technology required to produce optical devices such as optical devices requiring high resolution in the minute region of the nanometer region. To simplify the chemical vapor deposition process.

Another object of the present invention is to provide a molybdenum metal mold having better mechanical properties than nickel metal mold in the metal mold stamper obtained through the replication technique.

Yet another object of the present invention is to simplify the process in fabricating a metal mold through a replication technique, and to realize a cost-effective and environmentally friendly treatment system for the processing gas.

A feature of the present invention for achieving the above object is to form a plating layer on a mask pattern which is a non-conductor for mass production of a diffractive optical element, and to reproduce the stamper made of a metal mold as a metal plate by electroplating and electroplating the mask pattern. ,

The stamper replication method,

Inserting a non-chain mask pattern into a PECVD chamber and checking a basic pressure to create a pressure atmosphere;

Supplying Ar gas as a carrier gas and H2 gas as a reaction gas to the PECVD chamber to set a process pressure;

Forming a plasma at the process pressure to introduce molybdenum gas as a source gas, activating a molybdenum compound in the mask pattern, and chemical vapor deposition to coat the mask pattern with molybdenum metal by chemical vapor deposition;

The molybdenum metal layer coated on the mask pattern is separated from the mask pattern, characterized in that the step of replicating the molybdenum metal mold stamper.

Figure 1 is a block diagram showing a replication technique of a conventional nickel metal mold stamper

2 is a diagram schematically illustrating a replication technique of a conventional nickel metal mold stamper.

3 is a flow chart of an electroless plating process

Figure 4 is a block diagram showing a replication technique of molybdenum metal mold stamper according to the present invention

5 is a schematic view of chemical vapor deposition equipment for the replication of molybdenum metal mold stamper according to the present invention;

6 is a schematic representation of a replication technique of the molybdenum metal mold stamper of the present invention.

* Description of the symbols for the main parts of the drawings *

51: mask pattern 52: CVD chamber

53: molybdenum metal layer 54: temper

Hereinafter, the present invention will be described with reference to the drawings.

4 is a block diagram illustrating a replication technique according to the present invention. 5 shows a schematic diagram of a chemical vapor deposition apparatus for replicating a stamper according to the present invention. Figure 6 is a schematic representation of the stamper replication technology of the present invention.

The present invention, as shown in Figure 4, the mask pattern manufacturing step (S50), the molybdenum metal mold production step (S60) by the chemical vapor deposition method, the metal mold stamper in the separation step (S70) of the master pattern and molybdenum metal mold stamper Is duplicated through a mask pattern.

Specifically, as illustrated in FIGS. 5 and 6, a photoresist is formed on a silicon wafer to produce a compact disk, a digital video disk, a hologram lens, or the like. In order to reproduce the stamper (stemper) made of a metal plate by replicating the glass plate recorded by the metal for mass production after storing the record by using, the non-conductive mask pattern 51 is charged into the PECVD chamber 52 Checking the basic pressure to create a pressure atmosphere, supplying Ar gas as a carrier gas and H2 gas as a reaction gas to the PECVD chamber 52 to set a process pressure, forming a plasma at the process pressure, Molybdenum chemical vapor deposition step of injecting molybdenum gas to the mask pattern 51 to the mask pattern 51, to the mask pattern 51 The coated molybdenum metal layer 53 is separated from the mask pattern 51 to replicate the molybdenum metal mold stamper 54.

This replication method is a method of metal replication by Mo PECVD (Molybdenum Plasma Enhanced CVD) method, which improves the disadvantages of two processes: electroless plating for electrode formation and nickel plating method for electroplating for deposition thickness. Has characteristics.

Molybdenum Chemical Vapor Deposition (Mo PECVD), which is applied to replicate the stamper from the master pattern, has various characteristics due to better thickness uniformity, higher density, and wider control range of process conditions than electroforming. Eggplant is capable of depositing a deposited film, it is easy to control the mechanical properties and deposition rate, and has the advantages of an environmentally friendly process that does not require additional facilities such as waste water treatment facilities. Mo (CO) 6 used in molybdenum chemical vapor deposition has a great advantage that the decomposition temperature is low and not harmful. Molybdenum is defined by the NFPA (American Society of Materials Science) grades: grade health = 1, fire = 1, reactivity = 0.

As a mechanical property, molybdenum has higher strength than nickel, and has good heat resistance and abrasion resistance, thereby reducing the deformation of the stamper during the replication process.

As shown in FIG. 3, the master pattern is charged into the chamber, the base pressure is checked, the process pressure is adjusted with the Ar carrier gas and the H2 reaction gas, the plasma is formed, and the source gas is introduced to the PECVD apparatus for depositing molybdenum on the mask pattern. Through the replication method of the stamper, molybdenum metal can be coated directly on the insulator master pattern.

At this time, the molybdenum metal is coated on the mask pattern with Mo (CO) 6 + H 2 + Mo + 6CO + 2H under the condition that the thermal decomposition temperature is 150 ℃.

In general chemical vapor deposition (CVD), Mo is deposited on the surface when the surface temperature of the deposit reaches 150 ° C. However, when the molybdenum compound is activated by plasma, the thermal decomposition temperature can be lowered to about 50 to 70 ° C., which is a reaction temperature lower than 90 ° C., which is a temperature range used in the electroplating method.

The characteristic of PECVD is that the deposition rate is very fast (100㎛ / hr) and the hardness value after deposition is about 70 ~ 80 HrC, which is superior to 24 ~ 35 HrC of nickel plating, and the deposition temperature is about 250 ℃, compared to normal CVD. low.

When the PECVD method is used, it is possible to deposit at around 50 ° C, and the transferability at the interface shows that there is no gap even if the curve is within 100 nm under the electron microscope observation. Therefore, it can be provided with a replication technology that is more precise, cheaper and more productive than the existing methods.

Table 1 compares the mechanical properties and properties of molybdenum for nickel.

Bulk-Mo (Mo Film) Bulk-Ni (Ni Film) Surface density at 20 ° C (g / cm 3) 10.2 8.9 Melting Point (℃) 2615 1455 Thermal Conductivity (W / m k) 137 88.5 Coefficient of thermal expansion (/ k) 5.1 × 10-6 13.3 × 10-6 Tensile Strength (Mpa) 420 317 Yield strength (Mpa) 300 59 Longitude (annealcd, HV) 150 64

In addition to the mechanical properties shown in Table 1, molybdenum is superior to nickel in terms of heat resistance and abrasion resistance, and its life is prolonged. Mo (CO) 6 is not toxic and thus does not require a recycling / recovery system, which is an accessory treatment device. It acts as an advantageous factor.

The present invention can simplify the process compared to the nickel electroplating method of replicating the stamper through two processes of electroless plating for electrode formation and electroplating for deposition thickness formation.

In addition, the thickness of the plating layer, which is a thin film, on the mask pattern is maintained in a constant state to maintain a constant surface density and uniformity affecting the replication quality.

It is possible to compose the mechanical properties according to the process conditions to adapt to the variety of products, the large density of the thin film layer can be duplicated excellent metal stamper with less defects in the thin film layer.

It contributes to the prevention of water pollution and environmental pollution by suppressing the emission of harmful substances to human body and environment as much as possible, and it is not necessary to consider the design of the construction of water treatment system and recycling system for waste water treatment.

Therefore, it can be presented as a duplication technology suitable for the development needs of the precision measuring device and the information and communication field as well as the image media, the printing and the advertising media in the digital industry. In particular, holographic optics are applied to optical information processing, ultrafast signal processing, optical computing devices, optical integrated circuits, optical interconnects, etc., and are used in a wide range of fields such as precision measuring devices, laser printers and laser disk pickup devices, and optical devices such as bar code readers. Considering its use in optical equipment, the new copying technology has a large ripple effect.

As described above, according to the present invention, two processes, electroless plating and electroplating, which are core processes in the stamper replication technology required to produce optical devices such as diffractive optical devices requiring high resolution in the minute region of the nanometer region, are required. Simplifies the chemical vapor deposition process to enable mass production and mass productivity, and provides more stable replication technology by providing molybdenum metal mold with better mechanical properties than nickel metal mold obtained through replication technology. It has the effect of providing environmentally friendly cloning technology that lowers costs and reduces water treatment and environmental pollution.

Claims (2)

In order to replicate the stamper made of a metal mold, which is a metal plate, by forming a plating layer on a mask pattern which is a non-conductor for mass production of fine parts in a nanometer region such as an optical device, The stamper replication method, Inserting a non-conductive mask pattern into the CVD chamber and checking the basic pressure to create a pressure atmosphere; Supplying Ar gas as a carrier gas and H2 gas as a reaction gas to the CVD chamber to set a process pressure; A chemical vapor deposition step of introducing molybdenum gas as a source gas at the process pressure, and coating the mask pattern with molybdenum metal by chemical vapor deposition of the molybdenum compound on the mask pattern; The molybdenum metal mold stamper of claim 1, wherein the molybdenum metal mold stamper by separating the molybdenum metal layer coated on the mask pattern from the mask pattern to duplicate. The method of claim 1, A method of duplicating a molybdenum metal mold stamper using PECVD (Plasma Chemical Vapor Deposition) to form a plasma under the process pressure conditions to activate and maintain a molybdenum compound with respect to a mask pattern, thereby lowering and stabilizing chemical vapor deposition temperature. .