Variable time etching system according to the accumulated...

Details Variable time etching system according to the accumulated... Variable time etching system according to the accumulated...

1999-06-22

2002-12-17

Gulakowski, Randy (Department: 1746)

Etching a substrate: processes

Nongaseous phase etching of substrate

Recycling, regenerating, or rejunevating etchant

C216S023000, C216S024000, C216S084000, C216S091000

Reexamination Certificate

active

06495055

ABSTRACT:

BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an etching system and a method for fabricating microelectronics devices such as a semiconductor device or a liquid crystal display (LCD). More particularly, the present invention relates to an etching system and a method that varies an etching period according to the accumulated number of microelectronics devices being etched.
(b) Description of the Related Art
Microelectronics devices such as a semiconductor device or an LCD are formed by integrating a plurality of minute patterns. The patterns are formed by a variety of fabrication steps, one of which is an etching process. There are two main types of etching in microelectronics fabrication: wet etching and dry etching. A wet etching method uses liquid etchants while a dry etching method uses plasma.
The conventional wet etching process for an LCD will be described hereinafter.
In the LCD manufacturing process, it is necessary to form metal patterns of gate lines and data lines. These metal patterns are etched using an etchant containing nitric acid (HNO
3
). A large number of LCDs repeatedly use the same etchant of a certain amount in order to reduce the manufacturing costs. However, the more LCDs are etched (in other words, an “accumulated process number” increases) in the same etchant of a certain amount, the less nitric acid component remains in the etchant, resulting in a lowered etching rate. Thus, if LCDs are etched for the same period of time without considering the accumulated process number of substrates that the etchant fabricated, a critical dimension (CD) of the metal patterns increases as the accumulated process number increases.
FIG. 1
shows a graph illustrating a relation between the accumulated process number and the CD in the conventional process for manufacturing an LCD.
In the conventional process for manufacturing an LCD, LCDs are etched for a predetermined amount of time (at an overetching rate), without considering the accumulated process number. As shown in
FIG. 1
, in the conventional process for manufacturing LCDs, the CD increase has an almost linear relationship with the increase in the accumulated process number. Accordingly, the conventional LCD manufacturing process requires changing the etchant when the accumulated process number reaches a certain value (CDo), e.g., 300 devices, where the CD also reaches its tolerance point.
As a result, the conventional LCD manufacturing method wastes etchants a lot, thereby increasing the overall manufacturing costs.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide an etching system and a method for fabricating microelectronic devices that varies the etching period according to the accumulated process number of microelectronic devices that the etching system has handled.
To achieve the above object, the present invention provides an etching system and a method. The method according to the present invention etches the layers on a plurality of substrates using the same etchant of a certain volume to form a pattern on each of the layers, but changes the etching period according to the accumulated process number of substrates.
According to a feature of the present invention, the LCDs are etched at first for a period of T
1
until the accumulated process number reaches N substrates, and are etched for a period of T
2
when the accumulated process number goes beyond N substrates.
According to another feature of the present invention, the etching period varies for each different accumulated process number.
According to yet another feature of the present invention, substrates are etched using a functional value of a process time with regard to the accumulated process number.
According to still yet another feature of the present invention, optimal etching periods for different accumulated process numbers are obtained through experimental tests, and the optimal etching periods are stored in a memory and used to perform etching.
The etching system includes an etching equipment having an etching processor for etching layers on a plurality of substrates using an etchant to form a predetermined pattern on each of the layers, and a loader for temporarily holding cassettes that store the substrates; and a controller for controlling operations of the etching equipment. The etching equipment changes the etching period according to an accumulated process number of the substrates.
According to a feature of the present invention, the controller transmits to the etching equipment a first operation recipe including a first etching period T
1
when the accumulated process number is between 1 and N substrates, and a second operation recipe including a second etching period of T
2
when the accumulated process number is N+1 or more substrates; and wherein the etching equipment performs etching according to the first operation recipe and the second operation recipe.
According to another feature of the present invention, the controller receives data corresponding to the accumulated process number from the etching equipment when a cassette is loaded on the loader, and transmits the first operation recipe or the second operation recipe to the etching equipment according to the received data.
According to yet another feature of the present invention, the etching equipment etches substrates using the etching period that varies depending on each different accumulated process number.
According to still yet another feature of the present invention, the etching equipment etches substrates using a functional value of a process time with regard to the accumulated process number, the functional value being stored in a memory, and the etching equipment uses the functional value to perform etching.
According to still yet another feature of the present invention, optimal etching periods for different accumulated process numbers are obtained through tests, and the optimal etching periods are stored in a memory and used for etching by the etching equipment.


REFERENCES:
patent: 5221421 (1993-06-01), Leibovitz et al.
patent: 5308447 (1994-05-01), Lewis et al.
patent: 5980771 (1999-11-01), Cowan

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