Cleaning and liquid contact with solids – Processes – Combined
Reexamination Certificate
2000-10-12
2003-07-15
Stinson, Frankie L. (Department: 1746)
Cleaning and liquid contact with solids
Processes
Combined
C134S025400, C134S036000
Reexamination Certificate
active
06592678
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a cleaning method and equipment for dipping an object to be treated, such as a semiconductor wafer or a glass substrate for a LCD, into a cleaning solution, such as a chemical or pure water, to clean the object.
2. Related Background Art
In a typical production process for a semiconductor equipment, there is widely adopted a cleaning equipment for sequentially dipping objects to be treated, such as semiconductor wafers or glasses for LCDs, (which will be hereinafter referred to as “wafers”), into a cleaning solution, e.g., a chemical, such as aqueous ammonia (NH
4
OH) or hydrofluoric acid (HF), and/or a rinsing solution (pure water), which are stored in a cleaning bath, to clean the objects.
As a conventional cleaning equipment of this type, there is widely used a cleaning equipment wherein a cleaning bath for storing therein a cleaning solution to dip objects to be treated into the cleaning solution to clean the surfaces thereof is connected to a pure water supply source by means of a cleaning solution supply pipe which is connected to a chemical storing container for storing therein a chemical, the chemical in the chemical storing container being pressurized by an inert carrier gas, such as nitrogen (N
2
), to be injected into pure water flowing through the cleaning solution supply line so that a predetermined concentration of chemical is supplied to the cleaning bath to clean the objects.
However, in the conventional cleaning equipment of this type, since the chemical stored in the chemical storing container is pressurized by the inert gas, such as N
2
gas, to be injected into the pure water line, the injection speed of the chemical injected into the pure water line is set to be constant, so that there is a problem in that it is difficult to change the injection speed within a short time.
Therefore, there are problems in that it is not possible to quickly and appropriately control the injection speed of the chemical in order to obtain an appropriate concentration of cleaning solution corresponding to the conditions of the objects to be treated, and it is not possible to sufficiently supply the appropriate concentration of cleaning solution corresponding to the conditions of the objects to be treated, so that cleaning efficiency and yields deteriorate.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a cleaning method and equipment which can improve cleaning efficiency by injecting a predetermined amount of chemical into pure water to use a predetermined concentration of cleaning solution corresponding to the conditions of objects to be treated.
It is another object of the present invention to provide a cleaning method and equipment which can improve treatment efficiency with a simple construction and which can decrease the number of gas-liquid surface passages to decrease the amount of adhered particles and to improve etching uniformity.
In order to accomplish the aforementioned and other objects, according to one aspect of the present invention, a cleaning method comprises the steps of: dipping an object to be treated, into pure water to clean the object; and thereafter, controlling the concentration of a chemical in a cleaning solution which is prepared by injecting the chemical into the pure water, and dipping the object into the cleaning solution to clean the object.
Thus, after the object is dipped in the pure water to be cleaned, when the object is dipped in the cleaning solution, which is prepared by injecting the chemical into the pure water, to be cleaned, the concentration of the chemical in the cleaning solution can be changed to a predetermined concentration within a short time. Therefore, it is possible to improve the chemical cleaning efficiency for the object and it is possible to improve the throughput for the whole cleaning.
The amount of the chemical injected into the pure water may be changed on the basis of the temperature of the cleaning solution to control the concentration of the chemical in the cleaning solution. Thus, the concentration of the cleaning solution can be the optimum concentration based on the environment temperature of the object, so that it is possible to improve the chemical cleaning efficiency for the object and it is possible to improve the throughput for the whole cleaning.
The amount of the chemical injected into the pure water may be changed step-wise during one step, to control the concentration of the chemical in the cleaning solution. Thus, during the step of dipping the object in the cleaning solution, which is prepared by injecting the chemical into the pure water, to clean the object, a large amount of chemical can be injected at the initial stage of the cleaning step to prepare a high concentration of cleaning solution by gradually changing the amount of the injected chemical. Therefore, it is possible to reduce the time for unstable concentration of the cleaning solution diluted by dipping the object, and it is possible to improve cleaning efficiency.
The amount of the chemical injected into the pure water may be changed on the basis of the amount of the pure water supplied, to control the concentration of the chemical in the cleaning solution. Thus, the optimum concentration of cleaning solution based on the amount of the supplied pure water can be prepared by changing the amount of the injected chemical on the basis of the amount of the supplied pure water. Therefore, it is possible to improve the chemical cleaning efficiency for the object, and it is possible to improve the throughput for the whole cleaning.
According to another aspect of the present invention, there is provided a cleaning method for dipping an object to be treated, into a cleaning solution stored in a cleaning bath, to clean the surface of the object, the cleaning method comprising the steps of: a first cleaning step for injecting a chemical, which is diluted to a predetermined concentration with pure water continuously supplied in said cleaning bath, into said cleaning solution and for allowing said cleaning solution in said cleaning bath to overflow to clean said object; a second cleaning step for controlling the temperature of the diluted chemical in the cleaning bath so as to be a predetermined temperature and circulating the diluted chemical to clean the object while the supply of both of the pure water and the chemical is stopped when the concentration of the diluted chemical reaches a predetermined concentration; and a third cleaning step for allowing the pure water to overflow in the cleaning bath to clean the chemical adhered to the object.
Thus, when the concentration of the diluted chemical reaches a predetermined concentration after the chemical cleaning, while the supply of both of the pure water and the chemical is stopped, the temperature of the diluted chemical in the cleaning bath is controlled to be a predetermined temperature, and the diluted chemical is circulated to clean the object. Thus, it is possible to reduce consumption of the chemical, and it is possible to effectively utilize the chemical and to reduce the amount of adhered particles.
The cleaning method may further comprise a step for allowing the pure water to overflow to clean the object before said first cleaning step. Thus, when the concentration of the diluted chemical reaches a predetermined concentration after the pure water cleaning and the chemical cleaning, while the supply of both of the pure water and the chemical is stopped, the temperature of the diluted chemical in the cleaning bath is controlled, and the diluted chemical is circulated to clean the object. Thus, it is possible to reduce consumption of the chemical, and it is possible to effectively utilize the chemical and to reduce the amount of adhered particles.
According to a further aspect of the present invention, a cleaning equipment comprises: a cleaning bath for storing therein a cleaning solution and for allowing an ob
Kamikawa Yuji
Kitahara Shigenori
Shindo Naoki
Yamasaka Miyako
Morrison & Foerster / LLP
Stinson Frankie L.
Tokyo Electron Limited
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