Coating processes – Measuring – testing – or indicating
Reexamination Certificate
2000-09-26
2002-06-25
Bareford, Katherine A. (Department: 1762)
Coating processes
Measuring, testing, or indicating
C427S420000, C427S421100, C427S424000, C427S427000
Reexamination Certificate
active
06410080
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-272327, filed Sep. 27, 1999; and No. 2000-255461, filed Aug. 25, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
This invention relates to a liquid film forming method wherein a liquid is applied onto a substrate to be processed so as to form a liquid film.
In spin coating method, which has been used in lithographic steps, almost all of a liquid dropped onto a substrate is discharged outside the substrate so that a film is formed from the remainder thereof, which is several percent of the liquid. Therefore, most of the dropped liquid is of no use. Since most of the liquid is discharged, an adverse effect is produced on environment. Moreover, there arises a problem that in rectangle substrates or disc-shaped substrates having a large diameter of 12 inches or more, turbulent air is generated at the circumferential portion of the substrates so that the film thickness uniformity of this portion becomes deteriorated.
As a method of applying a liquid uniformly onto the whole of a substrate without vain use of the liquid, Jpn. Pat. Appln. KOKAI Publication No. 2-220428 describes a method of dropping a resist from many nozzles which are arranged along one line and, spraying from the back thereof, a gas or a liquid onto a film-forming surface to obtain a uniform film. Jpn. Pat. Appln. KOKAI Publication No. 6-151295 describes a technique wherein many spray nozzles are made in a rod and a resist is dropped out from them onto a substrate in order to obtain a uniform film. Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 7-321001 describes a method of using a spray head in which many spray nozzles for spraying a resist are made and moving the head relatively to a substrate to perform application.
In all of these applicators, plural dropping or spraying nozzles are arranged along one rank and they are scanned in order to obtain a uniform film. Besides application methods using a device having these nozzles, there is known a method of using a single liquid jetting-out nozzle and the nozzle is scanned over a substrate to be processed, so as to form a liquid film.
These methods have a problem that the processing time per substrate becomes long dependently on a method of handling the nozzle(s) or the use amount of a liquid gets very large.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a liquid film forming method making it possible to shorten processing time and suppress the use amount of a liquid.
In order to attain the above-mentioned object, the present invention is as follows.
(a) A first aspect of the liquid film forming method according to the present invention is a liquid film forming method of dropping a liquid adjusted to be spread into a give amount on a substrate to be processed from a dropping nozzle or dropping nozzles of a dropping unit onto the substrate, and then moving the dropping unit and the substrate relatively while keeping the liquid dropping on the substrate, so as to form a liquid film on the substrate,
wherein the relative movement of the dropping unit and the substrate is composed of straight movement along a file direction in which the dropping unit passes from one end side of the substrate through an upper space of the substrate to the other end side of the substrate, and movement along a rank direction outside the substrate,
movement length along the file direction is the sum of dropping length (L) over the substrate and length of an acceleration/deceleration section, and
movement speed (v) along the file direction over the substrate is defined dependently on the square root of the product of the dropping length (L) and the absolute value of acceleration/deceleration (a) within the acceleration/deceleration section.
(b) A second aspect of the liquid film forming method according to the present invention is a liquid film forming method of dropping a liquid adjusted to be spread into a give amount on a disc-shaped substrate which is to be processed and has a diameter (D) has from a dropping nozzle or dropping nozzles of a dropping unit above the substrate, and then moving the dropping unit and the substrate relatively while keeping the liquid dropping on the substrate, so as to form a liquid film on the substrate,
wherein the relative movement of the dropping unit and the substrate is composed of straight movement along a file direction in which the dropping unit passes from one end side of the substrate through an upper space of the substrate to the other end side of the substrate, and movement along a rank direction outside the substrate, and
movement speed (v) along the file direction is defined dependently on the square root of the product of constant 0.4, the diameter (D) of the substrate, and the absolute value of acceleration/deceleration (a) before and after the time when the movement speed (v) is given.
Preferred embodiments of the above-mentioned inventions are as follows.
Dropping amount (W) from the dropping nozzle or the dropping nozzles of the dropping unit positioned over the substrate is defined dependently on an amount proportional to the movement speed (v).
The dropping unit has plural dropping nozzles and the dropping amount (W) is the total amount of the liquid dropped from all of the dropping nozzles.
The liquid is any one selected from an antireflection material, a resist material, a low dielectric material, an insulating material, a wiring material and a metal paste.
The liquid film is formed, using the liquid having a characteristic that when a minute amount of the liquid is dropped onto a minute area of the substrate, a change amount of a contact angle of the liquid to the substrate is within ±2 degrees during a time from 5 seconds to 60 seconds after the dropping of the liquid.
(c) A third aspect of the liquid film forming method according to the present invention is a liquid film forming method of dropping a liquid adjusted to be spread into a give amount on a substrate to be processed from a dropping nozzle or dropping nozzles of a dropping unit onto the substrate, and then moving the dropping unit and the substrate relatively while keeping the dropped liquid on the substrate, so as to form a liquid film on the substrate,
wherein the relative movement of the dropping unit and the substrate is composed of straight movement along a file direction in which the dropping unit passes from one end side of the substrate through an upper space of the substrate to the other end side of the substrate, and movement along a rank direction outside the substrate, or is composed of spiral movement in which the dropping unit goes from the substantial center of the substrate to the periphery thereof or from the periphery of the substrate to the substantial center thereof, and
a change amount of a contact angle of the liquid to the substrate is within ±2 degrees during a time from 5 seconds to 60 seconds after the dropping of the liquid when a minute amount of the liquid is dropped onto a minute area of the substrate.
A preferred embodiment of the above-mentioned invention is as follows.
Control of the change amount of the contact angle of the liquid dropped onto the substrate to the substrate within ±2 degrees is attained by adjusting the ratio of a surfactant to a solvent and an application agent constituting the liquid.
(d) The liquid for application according to the present invention is a liquid for application used in a liquid film forming method of dropping the liquid adjusted to be spread into a give amount on a substrate to be processed from a dropping nozzle or dropping nozzles of a dropping unit onto the substrate, and then moving the dropping unit and the substrate relatively while keeping the dropped liquid on the substrate, so as to form a liquid film on the substrate,
comprising a solvent, an application agent, and a surfactant,
wherein the ratio of the surfactant to the solvent a
Bareford Katherine A.
Kabushiki Kaisha Toshiba
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