Method for forming a titanium dioxide layer

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

1999-08-04

2001-06-26

Bowers, Charles (Department: 2813)

Semiconductor device manufacturing: process

Coating of substrate containing semiconductor region or of...

Insulative material deposited upon semiconductive substrate

C438S240000, C438S758000, C438S763000, C438S781000, C427S126300, C428S432000

Reexamination Certificate

active

06251803

ABSTRACT:

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 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.
Our previous U.S. patent application Ser. No. 09/306,080 discloses a method to solve the above-described problems. This method is characterized by that nitric acid is added to the raw material H
2
TiF
6
for increasing the growth rate of the titanium dioxide layer and enhancing its stability. However, the current leakage of the formed titanium dioxide layer is still not low enough and there still exists some space to improve its quality.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for forming a titanium dioxide layer on a device.
Another object of the present invention is to provide a method for forming a titanium dioxide layer by liquid phase deposition to improve the quality of titanium dioxide layer and effectively avoid the occurrence of current leakage.
Another yet object of the present invention is to provide a method for forming a titanium dioxide layer which can greatly increase the deposition rate of the titanium dioxide layer.
The method includes the steps of providing a titanium-containing material, adding hydrogen chloride and nitric acid to the titanium-containing material to obtain a mixture, and exposing the device to the mixture to form the titanium dioxide layer thereon
Preferably, the titanium-containing material is H
2
TiF
6
. The concentration of the titanium-containing material ranges from 0.1M to 6.1M.
Preferably, the concentration of hydrogen chloride ranges from 0.001M to 0.1M and the concentration of nitric acid ranges from 0.1M to 0.5M.
The suitable device can be a semiconductor device, a silicon substrate, an integrated circuit, or 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 ranging between 20° C. to 80° C. for 2 to 30 minutes.
The forming rate and the refractive index of the titanium dioxide layer are controlled by the volume or concentration of hydrogen chloride.
The current leakage of the titanium dioxide layer can be controlled by the volume or concentration of hydrogen chloride.
The flat-band voltage shift and the effective oxide charge of the titanium dioxide layer are controlled by the volume or concentration of hydrogen chloride.
Another further 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 (e.g. a silicon substrate), 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: 5811192 (1998-09-01), Takahama et al.
patent: 6066359 (2000-05-01), Yao et al.

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