KR20050121046A - Method of fabricating tungsten-tellurite glass thin film and wide-band plannar amplifier having the tungsten-tellurite glass thin film - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband flat panel amplifier, and more particularly, to a method for producing a tungsten-tellurine glass thin film and a wideband flat panel amplifier having a tungsten-telluric glass thin film.

The present invention comprises the steps of preparing a target of tungsten tellurite (TeO ₂ -WO ₃ ) by using a solid-phase sintering method of Tellurium (VI) oxide and tungsten oxide (Tungsten (VI) oxide); Washing the base material; And depositing the target material on the base material using RF sputtering in a deposition chamber to form a tungspen-tellurite thin film.

Description

 Method for Fabricating Tungsten-Tellurite Glass Thin Film and Wide-Band Plannar Amplifier Having the Tungsten-Tellurite Glass Thin Film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband flat panel amplifier, and more particularly, to a method for producing a tungsten-tellurine glass thin film and a wideband flat panel amplifier having a tungsten-telluric glass thin film.

In general, an optical fiber amplifier used in an optical communication system is limited in relay distance due to loss characteristics and in transmission bandwidth due to dispersion characteristics.

Due to the increased loss due to the relay distance, the number of wavelength division multiplexing (WDM) channels is limited, so it is necessary to amplify the optical signal directly without electrical conversion.

Recently, Erbium Doped Fiber Amplifier (EDFA) has been put into practical use in place of the conventional fiber amplifier. EDFA is a special material called erbium that is doped into an optical fiber and is widely used in broadband wavelength division multiplexed transmission systems.

EDFA's amplification principle is to directly amplify weak optical signals by pumping light energy using a laser diode with a wavelength of 1.48 µm as a pump light source.

This EDFA uses silica glass as a base material. The reason for using silica glass in EDFA is that the material is similar to the optical fiber, so the transmission loss is small, the connection loss with the optical fiber is small, and the temperature stability is achieved. However, EDFAs based on silica glass typically have a full width at half maximum (FWHM) of the emission peak in the 1550 nm wavelength band. This half-width value is insufficient to be used in a broadband transmission system for transmitting a large amount of information.

Therefore, a method to widen the gain flattening bandwidth should be prepared. One method is to use tellurium glass having a half width of the emission peak in the 1550 nm wavelength band of about 80 nm. Tellurite glass has a large transmission area (0.35 ~ 6mm), has good glass stability, has the lowest vibration energy among glass formers (for example about 780cm ^-1 ), high refractive index and low process temperature It has the advantages of high nonlinear refractive index and good chemical durability.

 The advantages of this tellurite glass are as follows. Firstly, it has a wider transmission area of 0.35 to 5 µm than silicate glass having a transmission area of 0.2 to 3 µm. Secondly, it has good glass stability and corrosion resistance compared to the fluoride glass. Among the glass formers, they have relatively low photon energy (maximum phonon energy is about 800 cm −1), and the fourth fluoride glass (n = ˜1.5; n2 = ～ 10-21 m 2 / W) or silicate glass ( It has a high refractive index (n = 1.8-2.3) and a high nonlinear refractive index (n2 = 2.5 × 10-19 m 2 / W) compared to n = -1.46, n2 = -10-20 m 2 / W. The tellurite glass also has the largest bandwidth compared to other materials due to the uniqueness of the TeO4 structure. For example, in the 1550 nm wavelength region, a half band width of 85 nm is very likely to be a host material for broadband EDFA. Therefore, it can be used for DWDM in high capacity optical communication.

However, there are two drawbacks to using tellurium glass as an EDFA for wideband signal transmission. The first is that the phonon energy is relatively slow to spread to 770 cm ^-1 , so it can't pump in the 980 nm wavelength band, and secondly, the softening temperature is low at 290 ° C, which can lead to thermal damage at high optical intensities.

Therefore, an object of the present invention is to provide a glass thin film having excellent thermal characteristics in a broadband amplifier.

Another object of the present invention is to provide an optical fiber amplifier having a glass thin film having excellent thermal characteristics described above.

According to the present invention, a tungsten-tellurite thin film glass manufacturing method according to the present invention uses tellurium oxide and tungsten oxide by using a solid-phase sintering method of tellurium (VI) oxide and tungsten (VI) oxide. Preparing a target having a composition ratio of 70:30; Washing the base metal using acetone, methyl alcohol, ethyl alcohol and distilled water; And arranging the film by argon (Ar) and oxygen (O ₂ ) on the silicon substrate, wherein the pressure in the chamber is 3 × 10 ⁻⁶ torr, and the base material is a silicon substrate or corning glass. Includes.

The distance between the base material and the target is 7 cm, the room temperature is 50 ℃ to 100 ℃, the process pressure is 5mTorr to 15mTorr and the optimum process pressure is 5mTorr.

The distance between the base material and the target is maintained at 7cm, the RF power is 30W to 120W and the optimal RF power is 60W.

The present invention also features a broadband flat panel amplifier having a tungsten-tellurine glass thin film.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example

1A, 1B, and 1C, a process diagram for producing a tungsten-tellurite glass thin film according to the present invention is shown.

As shown in FIG. 1A, in preparation for forming a tungsten-telelite glass thin film, 70 mol% of 99.9% purity of Tellurium (VI) oxide and 99.99% purity of Tungsten (VI) oxide are used. A 30-mol% solid-phase sintering method was used to make a 2-inch target of TeO ₂ -WO ₃ .

As can be seen in Figure 1b, the substrate, for example, a silicon (001: vertical upward crystalline) substrate or corning glass (corning glass) is washed with acetone, methyl alcohol, ethyl alcohol and distilled water for 5 minutes each.

In the present invention has been described that the step of making the target first and then washing the base material, it will be appreciated that the steps of making the target first and then washing the base material may proceed sequentially.

As shown in FIG. 1C, a target of TeO ₂ -WO ₃ and a silicon substrate or corning glass are placed in a deposition chamber, such as an RF sputtering apparatus, and reactive gases such as argon (Ar) and oxygen (O ₂ ) are added. Is used to deposit the material of the target onto a silicon substrate or corning glass. At this time, the inside of the chamber is made of 3 × 10 ^-6 torr by using a turbopump, and the distance between the target and the silicon substrate or the corning glass is maintained about 7 cm. Here, 7cm is the distance that the target material can be deposited on the base material when electrons are shot at the target.

Sputtering apparatus is the thin film manufacturing apparatus currently used most commonly in the industry. The sputtering device injects argon (Ar) or other reactive gas into the chamber and then generates a plasma, which causes atoms and molecules sputtered out of the target to reach the substrate to form a thin film. In this case, the RF power helps to form a plasma layer between the target and the base material so that tungsten-tellite is well deposited on the base material.

Table 1 below shows the temperature of the base material, the amount of argon and oxygen gas flowing, the process pressure, and the power in the RF sputtering apparatus.

Table 1 .

Temperature ( ^oC ) Room temperature, 50, 70, 85, 100 Process pressure (mTorr) 5, 10, 15 RF power (W) 30, 60, 90, 120 Ar / O ₂ shedding amount (sccm) 0/40, 10/30, 20/20, 30/10, 40/0 Deposition time (min) 60

 Hereinafter, the characteristics of each process condition necessary for manufacturing the tungsten-tellurite glass thin film according to the present invention and the experimental results according to the characteristics will be described.

The crystallinity, microstructure and surface roughness of the glass thin film are X-ray diffractometer (XRD) (X`Pert-PRO, Phililps, Netherland), scanning electron microscope (SEM) (S-4700, Hitachi co., Japan) and It was investigated using an atomic force microscope (AFM) (nanoscope IV, Digital Instrument, USA). The thickness of the thin film was examined by using a scanning electron microscope, and the optical transmittance was measured by using a UV-VIR-IR spectrometer (U-3500, Hitachi co., Japan). The transmission spectrum of the thin film was measured in the wavelength range of 300nm to 1100nm. The refractive index was calculated using the measured transmission spectrum.

First, other process conditions were fixed under the same conditions as in FIGS. 1A, 1B, and 1C (60 W, 5 mTorr, 1 h), and the crystallinity of the substrate temperature was evaluated. As shown in FIGS. 2A and 2B, WO ₃ crystal peaks appear in all thin films except the thin film deposited at room temperature. These results show that when deposited at room temperature, a tungsten-telluric glass thin film is obtained.

3A, 3B, and 3C show data obtained by performing surface, cross-section, and component analysis of a tungsten-tellurite thin film deposited at 60 W, 5 mTorr, and Ar: O 2 (20:20) using a scanning electron microscope. At this time, the microstructure and component analysis of the deposited tungsten-tellurite thin film was analyzed using a scanning electron microscope. As shown in FIG. 3, no crystal phases were observed through the surface and the cross section, and the presence of tellurium (Te), tungsten (W) and oxygen (O) was confirmed through component analysis.

4A, 4B and 4C are atomic force microscopy (AFM) showing the shape of the surface of the deposited tungsten-teleolite glass thin film with RF power and process pressure fixed at 60 W and 5 mTorr, respectively, and varying the Ar / O ₂ flow ratio. ) Is a picture. All AFM images of FIG. 4 had a uniform microstructure and obtained a surface roughness of 4 to 6 nm.

5A, 5B and 5C show the deposition rates of the deposited tungsten-telelite glass thin films with varying power and pressure gas ratios at room temperature, respectively. Deposition rate was confirmed to be affected by a lot of process variables. As the Rf power increased, the deposition rate increased as the process pressure decreased.

In particular, when the gas amount of argon and oxygen is changed from 40 sccm / 0 sccm to 0 sccm to 40 sccm, the change becomes larger. When deposited in an argon atmosphere, the deposition rate was 0.2 µm / h, but 1.5 µm / h was also obtained in an oxygen atmosphere.

6A and 6B are graphs showing the transmission spectrum and the refractive index of a tungsten-tellurite glass thin film deposited at 60 W, 5 mTorr, and Ar: O ₂ (0:40).

At this time, the transmittance of the thin film deposited by using the Corning glass as a substrate was measured using a UV-VIR-IR spectrometer to measure the refractive index of the tungsten-tellurite glass thin film. Each was measured from 300 nm to 1100 nm. The interference fringe shows that the deposited thin film is uniform. The refractive index measured through the transmission spectrum of the thin film can obtain a refractive index of about 1.8 to 2.3, which is higher than that of the conventional silicate glass (about 1.45). It can also be seen that as the wavelength increases, the value of the refractive index decreases.

As described above, the process conditions of the tungsten-tellurite glass thin films deposited on the silicon substrate and the corning glass were investigated by using the RF magnetron sputtering method. All deposited at room temperature was confirmed to be amorphous. As the Rf power increased, the process pressure decreased, and the argon / oxygen ratio decreased, the deposition rate increased. The transmission spectrum was used to obtain a refractive index of 1.8 to 2.3, which was found to decrease as the wavelength was increased.

As described above, the tungsten-tellurite glass thin film according to the present invention can pump an optical signal having a wavelength band of 980 nm, and has strong optical properties in thermal damage.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Figures 1a, 1b and 1c is a process diagram illustrating a process for producing a tungsten- telluride glass thin film according to the present invention.

2a and 2b are graphs showing the crystallinity evaluation of the tungsten- telluride glass thin film prepared according to the present invention.

Figures 3a, 3b and 3c is a view showing the surface, cross-sectional and component analysis results of the tungsten- telluride glass thin film of the present invention, respectively.

4A, 4B and 4C are diagrams showing the shape of the surface of the tungsten-tellurite glass thin film of the present invention.

5A, 5B and 5C are the tungsten-tellurite glass thin films of the present invention, respectively.

Graph showing deposition rate versus RF power, temperature and gas conditions.

6A and 6B are graphs showing the transmission spectrum and the refractive index of the tungsten-tellurite glass thin film of the present invention.

Claims (11)

Preparing a target of tungsten tellurium (TeO ₂ -WO ₃ ) using solidus sintering of tellurium (VI) oxide and tungsten (VI) oxide; And depositing a material of the target on a base material using RF sputtering in a deposition chamber to form a tungsene-tellurite thin film. The method of claim 1, wherein the tungsten tellurite has a target of 70 mol% tellurium oxide and 30 mol% tungsten oxide. The method of claim 1, wherein the method further comprises the step of washing the base material. The method of claim 1, wherein the pressure in the chamber is set to 3 x 10 ^-6 torr. The method of claim 1, wherein the base material is a silicon substrate or corning glass. The method of claim 1, wherein the distance between the base material and the target is maintained at 7 cm. The method of claim 1, wherein the room temperature of the chamber is 50 ° C to 100 ° C. The method of claim 1, wherein the process pressure of the chamber is 5mTorr to 15mTorr. The method of claim 1, wherein the RF power in the deposition chamber is 30W to 120W. The method of claim 1, wherein the deposition time is 60 minutes.  A broadband flat panel amplifier having the tungsten-tellurite glass thin film according to claim 1 to 12.