KR100352645B1 - Planar silica optical waveguide manufactural method using the High Temperature Substrate and Flame Hydrolysis Deposition method - Google Patents

Abstract

The present invention relates to a method for manufacturing a flat silica optical waveguide for an optical device using a high temperature substrate chemical hydrolysis, and more specifically, to a chemical vapor deposition method for a flat silica optical waveguide device used in an optical communication network, an optical signal processing, and an optical sensor. And a method of fabricating a plate type silica optical waveguide for an optical device using a high temperature substrate flame hydrolysis method to suppress problems such as many process times, thin film uniformity, porosity, interfacial bonding defect or crystal phase, which are generated when fabricating by flame hydrolysis deposition method. It is about.

An object of the present invention is a method of depositing a thin film directly on a substrate, such as a FHD method, in order to remove defects such as process time, interfacial bonding defect, crystal phase and pores in a manufacturing process of a silica optical waveguide. Combination of methods to create flame atmosphere of acid / hydrogen, and to produce high quality silica optical waveguide device by pouring material gas such as SiCl ₄ , POCl ₃ , BCl ₃ , GeCl ₄ into the flame The present invention provides a method for manufacturing a self-propelled plate type silica optical waveguide.

The present invention for achieving the above object, the bottom clad layer deposition step of generating a bottom clad 110 by depositing a silica glass thin film on the silicon substrate 100; Additional germanium or phosphorus is added on the lower clad 110 to deposit silica fine particles so that the refractive index of the core silica film is greater than that of the lower clad 110 or the upper clad silica film so that light can be guided along the core layer. A core layer deposition step of generating a core layer 120; A dry-etch mask layer 230 such as a chromium (Cr) thin film is deposited on the core layer 120, an organic photo-resist 220 is applied, and a two-dimensional planar shape of the optical waveguide is formed. A transfer step of transferring the photosensitive film and the dry mask layer using a photo-mask 210 by photo-lithography and wet-etch; A dry etching step of etching the core silica layer into the rectangular channel optical waveguide 125 by using a dry etching method after the transfer step; It characterized in that the upper clad layer deposition step of depositing the upper clad silica fine particle layer 130 using the HTS-FHD method.

Description

Planar silica optical waveguide manufactural method using the High Temperature Substrate and Flame Hydrolysis Deposition method}

The present invention relates to a method for manufacturing a flat silica optical waveguide for an optical device using a high temperature substrate flame hydrolysis method, and more particularly, to a chemical vapor deposition method for a flat silica optical waveguide device used in an optical communication network, an optical signal processing, and an optical sensor. And a method of fabricating a plate type silica optical waveguide for an optical device using a high temperature substrate flame hydrolysis method to suppress problems such as many process times, thin film uniformity, porosity, interfacial bonding defect or crystal phase, which are generated when fabricating by flame hydrolysis deposition method. It is about.

Conventional methods of manufacturing silica flat optical waveguides include chemical vapor deposition (CVD), Flame Hydrolysis Deposition (FHD), ion exchange, sol-gel, sputter deposition, etc. This has been used mainly.

Among these methods, the best waveguide with the lowest optical loss is known as chemical vapor deposition and flame hydrolysis deposition. These two methods are a method for producing a silica flat waveguide film by chemically reacting in a reactor by using various gases or vaporizing various material solutions as the respective materials constituting the glass film used in the silica flat waveguide.

However, in the case of the CVD method, a high-quality optical waveguide film can be obtained, but it is difficult to find a condition for manufacturing a thin film having a high uniformity which requires a process time of several tens of hours or more in order to manufacture a thick film of 10-20 μm or more during the process. .

In addition, the CVD method is mainly developed for the application to electronic devices, the deposition rate is 0.01-0.05 ㎛ / min is very low, the contamination of the reaction tube is severe, the uniformity of the thin film has a disadvantage.

In the case of the FHD method, the difference in the active energy required for the reaction of each material gas is large and the difference in vapor pressure in the flame of each reactant is large, so that when a thin film having a composition different from the injected component ratio is deposited or the deposited particles are densified The highly volatile additives will vary greatly from the composition ratio of the actual deposited composition.

In addition, the FHD method deposits fine silica particles on a substrate such as silicon and melts them by a method similar to OVD (outer vapor deposition), an optical fiber manufacturing method, to make a glass thin film. This method has a very fast deposition rate of 0.2 ~ 1㎛ / min, but it requires the process of melting fine silica particles, and the thin film is easily contaminated by particles and dust generated during the heat treatment process or crystalline phase and phase separation in the thin film. do.

As mentioned above, when the planar silica optical waveguide device used for optical communication network, optical signal processing, or optical sensor is manufactured by chemical vapor deposition or flame hydrolysis deposition method, a lot of processing time, complexity of process conditions, crystal phase formation and After etching, interfacial bonding defects due to residual material and non-uniform composition layers, crystals and pore formation adjacent to the optical waveguide not only degrade the quality of the finished device, but also cause loss in production yield.

The present invention was devised to solve the above-mentioned problems, and an object of the present invention is to remove the defects such as process time, interfacial bonding defect, crystal phase and pores in the manufacturing process of silica optical waveguide, as in FHD method. is faster while a combination of a method of depositing directly a film on a substrate CVD method and the FHD method acid / hydrogen to create a flame atmosphere into flowing a material gas such as _{SiCl 4, POCl 3, BCl 3} , GeCl 4 in the flame high grade silica Disclosed is a method for manufacturing a flat silica optical waveguide for an optical device using a high temperature substrate hydrolysis deposition method for manufacturing an optical waveguide device.

The present invention for achieving the above object, the bottom clad layer deposition step of generating a bottom clad 110 by depositing a silica glass thin film on the silicon substrate 100; Additional germanium or phosphorus is added on the lower clad 110 to deposit silica fine particles so that the refractive index of the core silica film is greater than that of the lower clad 110 or the upper clad silica film so that light can be guided along the core layer. A core layer deposition step of generating a core layer 120; A dry-etch mask layer 230 such as a chromium (Cr) thin film is deposited on the core layer 120, an organic photo-resist 220 is applied, and a two-dimensional planar shape of the optical waveguide is formed. A transfer step of transferring the photosensitive film and the dry mask layer using a photo-mask 210 by photo-lithography and wet-etch; A dry etching step of etching the core silica layer into a rectangular channel optical waveguide 125 by using a dry etching method after the transfer step; It characterized in that the upper clad layer deposition step of depositing the upper clad silica fine particle layer 130 using the HTS-FHD method.

1 is a process chart of the manufacturing method of the plate-type silica optical waveguide for an optical device using the high temperature substrate hydrolysis deposition method according to the present invention,

2 is a schematic configuration diagram of an apparatus for manufacturing a plate-type silica optical waveguide for an optical device using a high temperature substrate hydrolysis deposition method according to the present invention;

3 is an electron micrograph of a cross section of a plate-shaped silica optical waveguide for an optical device using a high temperature substrate flame hydrolysis deposition method according to the present invention. <Description of the reference numerals in the drawings> 10: Air filter 20: Discharge fan 25: Outlet port 30: torch 40: wafer 50: high temperature substrate 60: XY stage 70: computer 100: silicon substrate 110: lower clad 120: core layer 125: channel optical waveguide 130: upper clad 210: exposure mask 220: organic photosensitive film 230: dry mask layer

Hereinafter, a method of manufacturing a plate type silica optical waveguide for an optical device using the high temperature substrate hydrolysis deposition method of the present invention will be described in detail with reference to the accompanying drawings.

1 is a process diagram of a method for manufacturing a plate type silica optical waveguide for an optical device using the high temperature substrate hydrolysis deposition method according to the present invention, Figure 2 is a plate type silica optical waveguide for an optical device using the high temperature substrate hydrolysis deposition method according to the present invention 3 is an electron micrograph of a cross section of a flat silica optical waveguide for an optical device using a high temperature substrate flame hydrolysis deposition method according to the present invention. Referring to FIGS. 1 to 3, a silicon substrate The lower clad layer deposition step of depositing a silica glass thin film on the (100) to produce a lower clad 110, and additionally adding germanium or phosphorus on the lower clad 110, which is the refractive index of the core silica film is the lower clad ( 110) or greater than the refractive index of the upper clad silica film so that light can be guided along the core layer to deposit silica particles A core layer deposition step of generating a fish layer 120, a dry-etch mask layer 230 such as a chromium (Cr) thin film is deposited on the core layer 120 and an organic photoresist (photo-resist) 220 ) And then apply the 2D planar shape of the optical waveguide to the photosensitive film and the dry mask layer using a photo-mask 210 by photolithography and wet-etch. A transfer step of transferring, a dry etching step of etching the core silica layer with a rectangular channel optical waveguide 125 by using a dry-etch method after the transfer step, and a HTS-FHD method. A top clad layer deposition step of depositing the upper clad silica fine particle layer 130 by using the CVD method or the FHD method at the time of depositing each of the silica fine particle layer process at the interface between the silica glass film or the substrate under the silica fine particle layer Residue or stress can be easily It is. Due to these process factors, the interface bonding becomes poor during the silica optical waveguide fabrication process and is a direct cause of crystal phase or pore formation adjacent to the optical waveguide. Usually, the upper clad layer is a thick film of 15 to 20 microns or more. As the deposition and densification process takes a lot of time, in particular, when the silica particles are melted from the top during the densification process, defects such as pores and crystal phases are easily generated, which not only degrades the performance of the optical waveguide device but also produces This results in loss of production rate and yield over time, such as the need to discard the device. Thus, in order to overcome the above disadvantages, the present invention provides a high temperature substrate hydrolysis deposition method (hereinafter referred to as HTS-FHD). Direct deposition of thin films with hot substrates and acid / hydrogen flames As, FHD method, unlike and because there is no process to dissolve the silica particles (soot) economy, deposited gamyeo moving the fire, because it can adjust the thickness and refractive index of the thin film is deposited by the wafer area where SiCl ₄ and other additives (dopant) Increasing the flow rate of MgO increases the deposition rate to more than 0.57 μm / min, which is much higher than other CVD methods (APCVD: 0.1 μm / min, LPCVD: 0.01 μm / min), which is particularly advantageous for making thick films. The refractive index can change the relative refractive index difference by more than 1.5% by controlling the flow rate of GeCl ₄ , which is useful for making waveguide film for optical integrated circuit. Especially in flame hydrolysis deposition, crystal phase by hydrate produced by adsorbed -OH etc. Or a region of non-uniform composition containing excessive amounts of boron (B) and phosphorus (P) at the periphery of the waveguide core and at the bottom during deposition of the upper clad silica fine particles. (It depends largely on the deposition direction of silica fine particles according to the substrate temperature and surface shape of the etch core or the mechanical properties of the interfacial fluid when the fine particles are deposited), and the stress difference according to the difference and composition of the volatilization or melting temperature during these densification processes However, when the optical waveguide film is manufactured by using the HTS-FHD method, the above problem can be completely eliminated since the film is converted into a glass film at the same time as the deposition of a hygroscopic additive. 2 is an apparatus for executing the HTS-FHD method, the air filter 10 for removing impurities in the outside air on one side of the upper side, the discharge fan 20 and the outlet port for discharging the burned air on the other side thereof ( 25), the torch 30, which is supplied with an external acid / hydrogen and heated at 1000 ° C or higher, the wafer 40 heated and deposited by the torch 30, and A high temperature substrate 50 deposited by the wafer 40, an XY stage 60 for adjusting the position of the high temperature substrate 50, and a computer for precisely controlling the XY stage 60 from the outside. In other words, the above-described apparatus can greatly reduce the defects generated during the manufacture of the optical waveguide film, and can also perform densification at the same time as the deposition, thereby greatly shortening the process time and moving the sample. The deposition of the material and the densification heat treatment can be performed simultaneously. FIG. 3 is a cross-sectional view of a BPSG (Boron-Phosphorus-Silica-Glass) waveguide film containing germanium according to the present invention. It shows that it is deposited uniformly.

In the process of fabricating the optical waveguide thin film, the optical waveguide and the optical waveguide device based on silicon by the deposition and densification method using the HTS-FHD method, the lower cladding and the core of the waveguide, or the upper clad silica glass thin film deposition process By carrying out the process using the simple device of the invention, it is possible to shorten the process time and eliminate defects such as crystal phase, pores, and interface defects, compared to the method using the conventional CVD and FHD. By performing the densification in the deposition process during the deposition process, it is possible to manufacture economical silica optical waveguide devices by increasing the economical efficiency of device fabrication and improving device performance as well as increasing production yield.

Claims (4)

A bottom clad layer deposition step of depositing a silica glass thin film on the silicon substrate 100 to produce a bottom clad 110; The addition of germanium or phosphorus on the lower clad 110 additionally deposits silica fine particles so that the refractive index of the core silica film is greater than that of the lower clad 110 or the upper clad silica film so that light can be guided along the core layer. A core layer deposition step of generating a core layer 120; A dry-etch mask layer 230 such as a chromium (Cr) thin film is deposited on the core layer 120, an organic photo-resist 220 is applied, and a two-dimensional planar shape of the optical waveguide is formed. A transfer step of transferring the photosensitive film and the dry mask layer using a photo-mask 210 by photo-lithography and wet-etch; A dry etching step of etching the core silica layer into a rectangular channel optical waveguide 125 by using a dry etching method after the transfer step; A method of fabricating a flat plate type silica optical waveguide for an optical device using a high temperature substrate hydrolysis deposition method comprising the step of depositing an upper clad layer depositing the upper clad silica fine particle layer 130 using the HTS-FHD method. delete delete delete