Method for forming a titanium dioxide layer

Details Method for forming a titanium dioxide layer Method for forming a titanium dioxide layer

1999-05-06

2001-05-29

Nelms, David (Department: 2818)

Semiconductor device manufacturing: process

Making field effect device having pair of active regions...

Having insulated gate

C438S767000

Reexamination Certificate

active

06238965

ABSTRACT:

FIELD OF THE INVENTION
The present invention is related to a method for forming a titanium dioxide layer.
BACKGROUND OF THE INVENTION
Generally, in the manufacturing processes for integrated circuits, semiconductor devices, and photoelectric devices, a titanium dioxide film has been extensively used. Titanium dioxide can be applied in a memory with a high capacity (such as dynamic random access memory (DRAM)) because of its higher dielectric constant, or can be applied in photoelectric devices (for example, waveguide, filter, antireflective coating, etc.) due to its high refractive index.
The most commonly used method for forming a titanium dioxide includes: (1) reactive sputtering; (2) sol-gel growing method which is performed at 800° C.; (3) plasma enhanced chemical vapor deposition which is executed at less than 400° C. However, high radiation generated in the sputtering process will damage the device. Moreover, high temperature required for the reactive sputtering process or sol-gel growing method also causes a damage to the fabricated device. If titanium dioxide can be grown at a lower temperature, the damage resulting from radiation and high temperature can be avoided.
Liquid phase deposition (LPD) is a method of forming a film at about room temperature so that this method has a great developing potential in the processes for manufacturing integrated circuits, semiconductor devices, and photoelectric devices.
In the previous studies about forming titanium dioxide film by liquid phase deposition, not only is the coverage of the formed titanium dioxide film not so good but also a few changes of the operating parameters will significantly influence the growth quality because of too slow deposition rate (less than 6 Å/min) and unstable growth. Therefore, the titanium dioxide film formed by the prior technique can not be applied in the production line due to low throughput and unstable quality.
Therefore, it is desirable to develop an effective method to solve the above-mentioned problems.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for forming a titanium dioxide layer on a device.
The method includes the steps of providing a titanium-containing material, adding an acid substance to the titanium-containing material to obtain a mixture, and exposing the device to the mixture to form the titanium dioxide layer thereon.
This method is characterized by that nitric acid is added to the raw material H
2
TiF
6
for increasing the growth rate of titanium dioxide layer and enhancing its stability. Because nitrous acid is often contained in nitric acid solution, both of them will spontaneously react with each other to provide a great number of electron holes so that elemental titanium can be reduced from the raw material H
2
TiF
6
and accepts the electron hole provided by nitric acid to form titanium ion and then to become titanium dioxide.
Preferably, the titanium-containing material is H
2
TiF
6
. The concentration of the titanium-containing material is about 6M.
The acid substance is one selected from a group consisting of nitric acid, boric acid, and a mixture thereof, wherein the concentration of the nitric acid is preferably ranged from 0.1M to 0.5M and the concentration of the boric acid is preferably ranged from 0.1M to 0.5M.
The suitable device is one selected from a group consisting of a semiconductor device, a silicon substrate, an integrated circuit, and a photoelectric device.
In accordance with one aspect of the present invention, the titanium dioxide layer is formed by a liquid phase deposition which is performed preferably at a temperature ranged between 20° C. to 40° C. for 2 to 30 minutes.
Another object of the present invention is to provide a method for forming a titanium dioxide layer on a semiconductor device. The method includes the steps of cleaning the semiconductor device, providing a titanium-containing material and adding an acid substance to the titanium-containing material to obtain a mixture, and exposing the cleaned semiconductor device to the mixture to form the titanium dioxide layer thereon.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which:


REFERENCES:
patent: 6066359 (2000-05-01), Yao et al.

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