Drying and gas or vapor contact with solids – Process – With nondrying treating of material
Reexamination Certificate
2003-03-04
2004-02-17
Lazarus, Ira S. (Department: 3749)
Drying and gas or vapor contact with solids
Process
With nondrying treating of material
C034S527000, C034S068000, C034S218000, C134S902000
Reexamination Certificate
active
06691430
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high pressure drying apparatus and a high pressure drying method in which a high pressure fluid or a mixture of a high pressure fluid and a chemical agent as a processing fluid is supplied to substrates, to thereby dry the substrates under a high pressure. The present invention relates also to a substrate processing apparatus comprising such a high pressure drying apparatus. The substrates include a semiconductor wafer, a glass substrate for photomask, a glass substrate for liquid crystal display, a glass substrate for plasma display and an optical disk substrate
2. Description of the Related Art
While electronic components such as semiconductor devices are becoming increasingly finer these days at an accelerating rate, there are new problems arising because of this during processing of substrates. For example, a developing process, a rinsing process and a drying process are performed in this order to form very fine patterns by means of patterning of a resist which is applied on a substrate. During an alkaline developing process for development of the resist applied on the substrate, an alkaline solution is used for removal of an unwanted resist. During rinsing, a rinse liquid such as pure water is used to remove the alkaline solution (to stop developing). During drying, the substrate is rotated to thereby make centrifugal force act upon the rinse liquid, the rinse liquid remaining on the substrate is accordingly removed, and the substrate is dried (spin drying). Of these processes, during the drying process, the interface between the rinse liquid and gas appears on the substrate as drying proceeds. If the interface appears at a gap between very fine patterns of a semiconductor device, the surface tension of the rinse liquid pulls the very fine patterns toward each other and collapses the very fine patterns, which is a problem.
It is also considered that the collapse of the very fine patterns is attributed to the flow resistance created at the time of spin drainage of the rinse liquid, the applied pressure developed at the time of ejection of the rinse liquid out from the very fine patterns, the air resistance and the centrifugal force due to the high-speed rotations beyond 3000 rpm, etc.
Proposed as a solution of this problem is supercritical drying during which a substrate is held inside a pressure container, a supercritical fluid (hereinafter referred to as “SCF”) which has low viscosity, high diffusivity and no surface tension is introduced into the pressure container, and the substrate is subjected to supercritical drying. One such a conventional technique is a supercritical drying apparatus described in Japanese Patent Application Laid-Open Gazette No. 2000-223467. This supercritical drying apparatus is capable of holding a developed and rinsed substrate inside a reaction chamber. A pump unit is activated with a substrate held, a constant amount of liquefied carbon dioxide is pumped under pressure into the reaction chamber from a cylinder, the pressure of carbon dioxide inside the reaction chamber is automatically controlled by means of a pressure control valve, the pressure of carbon dioxide inside the reaction chamber accordingly becomes 7.38 through 8 MPa, and carbon dioxide inside the reaction chamber consequently becomes a supercritical fluid. Supercritical carbon dioxide is thereafter released from the reaction chamber and the pressure inside the reaction chamber is reduced, whereby the substrate is dried.
By the way, the supercritical drying apparatus described above is a drying apparatus of the single wafer type which performs only drying. Therefore, after a different developing apparatus which is separate from the supercritical drying apparatus develops and rinses one substrate, this substrate is fed into the supercritical drying apparatus by a transportation apparatus and dried. Thus, a developing apparatus, a transportation apparatus and a supercritical drying apparatus are disposed within a conventional substrate processing apparatus, and substrates are processed one by one in each one of the developing apparatus and the supercritical drying apparatus. In short, the developing apparatus and the supercritical drying apparatus are both of the single wafer type.
As for comparison of a processing time per production lot between the developing apparatus and the supercritical drying apparatus, the processing time of the supercritical drying apparatus is longer than that of the developing apparatus. It is a reason that the supercritical drying apparatus requires an operation of increasing the pressure inside a reaction chamber and generating a supercritical fluid for the purpose of supercritical drying and thereafter releasing the supercritical fluid and decreasing the pressure inside the reaction chamber. Hence, the supercritical drying step becomes a causes of the throughput-determining of the substrate processing apparatus as a whole.
SUMMARY OF THE INVENTION
A major object of the present invention is to provide a high pressure drying apparatus, a high pressure drying method and a substrate processing apparatus with which it is possible to perform high pressure drying on substrates at an excellent throughput.
To achieve the object above, a high pressure drying apparatus according to the present invention comprises: a pressure container whose inside is a processing chamber; substrate housing means which is capable of housing a plurality of substrates inside the processing chamber; atmosphere creating means which provides the processing chamber with an anti-drying liquid for prevention of drying of surfaces of substrates or a vapor of the anti-drying liquid, to thereby create an anti-drying atmosphere; atmosphere removing means which removes the anti-drying atmosphere from the processing chamber; and processing fluid introducing means which introduces into the processing chamber a high pressure fluid or a mixture of a high pressure fluid and a chemical agent as a processing fluid, wherein after more than one substrate among substrates transported to the processing chamber are housed in the substrate housing means and made on stand-by in the anti-drying atmosphere, the more than one substrate housed in the substrate housing means are subjected all at once to high pressure drying.
To achieve the object above, a high pressure drying method according to the present invention comprises: a first step of supplying an anti-drying liquid, which prevents drying of surfaces of substrates, or a vapor of the anti-drying liquid to a processing chamber of a pressure container and creating an anti-drying atmosphere inside the processing chamber; a second step of receiving substrates transported to the processing chamber and making the substrates on stand-by in the anti-drying atmosphere; and a third step of removing the anti-drying atmosphere from the processing chamber after repeating the second step for a plurality of times, introducing a high pressure fluid or a mixture of a high pressure fluid and a chemical agent into the processing chamber as a processing fluid, and subjecting the substrates all at once to high pressure drying.
According to the present invention using such a structure (the high pressure drying apparatus and the high pressure drying method), more than one substrate among substrates transported to the processing chamber, as they are housed in the substrate housing means, are dried all at once under a high pressure, and therefore, the throughput dramatically improves as compared to a conventional apparatus which performs single wafer processing.
Batch type high pressure drying of drying more than one substrate all at once requires to consider the following points. Prior to high pressure drying of more than one substrate all at once, if substrates which have been already housed dry up naturally while transported substrates are housed one by one in the substrate housing means, very fine patterns pull each other and collapse because of the surface tension of the anti-drying l
Iwata Tomomi
Kitakado Ryuji
Miyake Takashi
Mizobata Ikuo
Muraoka Yusuke
Dainippon Screen Mfg. Co,. Ltd.
Lazarus Ira S.
O'Malley Kathryn S.
Ostrolenk Faber Gerb & Soffen, LLP
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