Cleaning and liquid contact with solids – Apparatus – With plural means for supplying or applying different fluids...
Reexamination Certificate
1999-05-17
2001-12-04
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
With plural means for supplying or applying different fluids...
C134S100100
Reexamination Certificate
active
06325081
ABSTRACT:
TECHNOLOGICAL FIELD
The present invention relates to a washing apparatus and a washing method for substrates, and in particular, relates to an ultra small washing apparatus which makes possible the rapid washing of semiconductor wafers or substrates for LCDs using small amounts of cleaning liquid.
BACKGROUND ART
In semiconductor manufacturing, the washing processes are key processes in carrying out oxidation and diffusion, epitaxial growth, silicide formation, thin film formation, ion implantation, dry etching, and pre- or post-processing such as various types of heat treatment and the like. The proportion of the total process steps occupied by the washing processes is approximately 30%, and the area of the clean room occupied by the supply facilities, preparation facilities, and transportation facilities of the large amount of ultra-pure water or cleaning liquid, and by the washing facilities, is very large. Furthermore, the number of washing processes has increased with increasing integration of the semiconductor devices.
On the other hand, the degree of cleanliness of the wafers has approached a completely clean state, and the size of the wafers has further increased to a level of 12 inches, so that it will be increasingly difficult to guarantee uniformity and completeness of the washing.
Liquid crystal display (LCD) substrate washing processes are essentially identical to semiconductor substrate washing processes and are also in need of a thorough revolution. In the following explanation, the case of semiconductor wafers will chiefly be discussed as a representative of both semiconductor wafers and LCDs.
In the course of studying washing processes, the present inventors learned that in the “job shop method” employed in conventional semiconductor substrate washing processes, that is to say, in the method in which the wafers are transported to a washing area in each process step and after washing are transported to the treatment apparatus of the following step, the wafer movement distance is extremely large, and during wafer movement, the washing surfaces become recontaminated, and this constitutes a hindrance to development of more highly functional devices. In order to solve such recontamination problems, it is necessary to change the washing method from the conventional “job shop method” to a closed manufacturing continuous treatment method in which a washing apparatus is coupled to each process treatment apparatus and the pretreatment is conducted for that process. In order to accomplish this, it is desirable that a number of washing apparatuses equal to the number of washing processes be installed, and a reduction in size of the washing apparatuses is important.
Furthermore, the conventional washing process is conducted by means of a “batch method” in which wafers are immersed in a washing tank in units of ten, or in other words, by a “wafer parallel washing format”. In order to increase throughput, it is necessary to reduce the gap between the parallel wafers, and as a result, it is fundamentally difficult to ensure uniformity of the insertion and discharge time of the washing solution per wafer, and the cleaning liquid flow. Furthermore, there is a drawback in that the front surface of the wafer is constantly affected by contamination from the rear surface of the wafer. Furthermore, there is also a problem in that time is required for the orderly movement of wafers to washing tanks having different cleaning liquids, and a large amount of time is required for the introduction of cleaning liquid into and discharge of cleaning liquid from the washing tanks.
Furthermore, in the conventional washing processes, there is a problem in that the amount of cleaning liquid or ultrapure water employed was very large.
The present invention has as an object thereof to solve the problems described above which were present in the conventional washing method. In other words, the present invention has as an object thereof to provide a washing apparatus which is capable of further improving the washing effect and enables highly clean washing using a small amount of chemicals.
Furthermore, it is an object to provide a washing apparatus of high throughput involving rapid switching of various chemicals of high responsiveness and capable of performing a series of washing operations at high speed.
Furthermore, it is an object to reduce the size of the washing apparatus itself.
Furthermore, the present invention has as an object thereof to provide a washing method which is capable of further improving the washing effect and which enables highly clean washing using a small amount of chemicals.
DISCLOSURE OF THE INVENTION
The washing apparatus of the present invention is provided with a cleaning liquid supply mechanism for supplying a cleaning liquid having a predetermined concentration simultaneously to front and rear surfaces of a substrate, a mechanism for superposing ultrasonic waves or high frequency sound waves of 0.5 MHz or more on the substrate through the cleaning liquid, and a mechanism for rotating the substrate or a mechanism for moving either of the substrate and the cleaning liquid supply mechanism in one direction, and this apparatus conducts washing of the substrate by means of the cleaning liquid.
The washing apparatus of the present invention is provided with an undiluted cleaning liquid injection mechanism for injecting an undiluted solution or an undiluted gas of a cleaning liquid into an ultrapure water channel to make a cleaning liquid of a desired concentration, a cleaning liquid supply mechanism connected to the ultrapure water channel which simultaneously supplies front and rear surfaces of a substrate with a cleaning liquid adjusted to a desired concentration or with ultrapure water, a mechanism for superposing ultrasonic waves or high frequency sound waves of 0.5 MHz or more on the substrate through the cleaning liquid, and a mechanism for rotating the substrate or a mechanism for moving either of the substrate and the cleaning liquid supply mechanism in one direction, and which is capable of continuously performing washing of the substrate by the cleaning liquid and washing the substrate by ultrapure water by controlling the injection of the undiluted solution or undiluted gas into the ultrapure water channel.
It is preferable that at least the substrate and the cleaning liquid supply mechanism be installed in a sealed container and that the substrate be washed in an inert gas atmosphere isolated from the outer atmosphere, and it is preferable that ultrapure water be employed which is subjected to deaeration treatment so that the concentration of dissolved gases is controlled.
The cleaning liquid supply mechanism supplies cleaning liquid to the front and rear surfaces of the substrate simultaneously using a nozzle which moves between the center and the periphery of the substrate, or alternatively, using a linear fixed nozzle which extends from the center in the circumferencial direction.
In the mechanism for superposing ultrasonic wave or high frequency sound waves of 0.5 MHz or more, oscillating elements which apply ultrasonic waves in the direction of the substrate are provided on the nozzles disposed on one side of the front and rear surface of the substrate or on both sides at non-overlapping positions.
When the ultrasonic waves or high frequency sound waves of 0.5 MHz or more are applied from one side, the angle of incidence of the ultrasonic wave or high frequency sound waves of 0.5 MHz or more to the substrate is preferably set so that the sound pressure at the surface opposite to the surface of incidence of the ultrasonic wave or high frequency sound waves of 0.5 MHz or more of the substrate is approximately maximal.
The undiluted cleaning liquid injection mechanism comprises a pump connected to the ultrapure water channel, and an undiluted solution container or undiluted gas container of the cleaning liquid; a prespecified amount of undiluted liquid or undiluted gas in injected into the ultrapure water channel, and cleaning liquid of a specified concentratio
Harada Yasuyuki
Miki Nobuhiro
Nitta Takahisa
Ohmi Tadahiro
Coe Philip R.
Kabushiki Kaisha Ultraclean Technology Research Institute
Knuth Randall J.
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