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Patent Issued for Substrate Treatment Method and Substrate Treatment Apparatus

September 10, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventor Nakamura, Kazuki (Kyoto, JP), filed on September 8, 2011, was published online on August 26, 2014.

The patent's assignee for patent number 8815111 is Dainippon Screen Mfg. Co., Ltd. (JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a substrate treatment method and a substrate treatment apparatus for treating a substrate with a treatment liquid. Examples of the substrate to be treated include semiconductor wafers, glass substrates for liquid crystal display devices, substrates for plasma display devices, substrates for FED (Field Emission Display) devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photo masks, ceramic substrates, and substrates for solar cells.

"In production processes for semiconductor devices and liquid crystal display devices, substrate treatment apparatuses of a single substrate treatment type are often used, which are adapted to perform a treatment on a single substrate (e.g., a semiconductor wafer or a liquid crystal display glass substrate) at a time for treating a front surface of the substrate with a chemical liquid.

"The substrate treatment apparatus of the single substrate treatment type includes a spin chuck which horizontally holds and rotates the substrate, a chemical liquid nozzle which supplies the chemical liquid to the front surface of the substrate rotated by the spin chuck, and a deionized water nozzle which supplies deionized water to a center portion of the front surface of the substrate rotated by the spin chuck.

"In the substrate treatment apparatus of the single substrate treatment type, the chemical liquid is supplied from the chemical liquid nozzle onto the front surface of the rotated substrate. Thus, the front surface of the substrate is treated with the chemical liquid (chemical liquid treatment step). After the supply of the chemical liquid is stopped, the deionized water is supplied from the deionized water nozzle onto the center portion of the front surface of the substrate. The deionized water supplied onto the front surface of the substrate receives a centrifugal force generated by the rotation of the substrate to flow toward a peripheral edge of the substrate over the front surface of the substrate. Thus, the chemical liquid is rinsed away from the substrate with the deionized water (rinsing step). In the rinsing step, the substrate is rotated at the same rotation speed as in the chemical liquid treatment step. The flow rate of the deionized water supplied from the deionized water nozzle is constant, and generally equals to a chemical liquid supply flow rate. After the supply of the deionized water is stopped, the rotation of the substrate is accelerated, and the deionized water is spun away from the substrate. Thus, the substrate is dried, and a series of treatment steps are completed.

"Two exemplary methods for supplying the chemical liquid to the substrate include a center spouting method, and a scanning method. In the center spouting method, the chemical liquid is spouted toward the rotation center of the front surface of the substrate rotated by the spin chuck (JP-A-2005-286221). In the scanning method, the chemical liquid nozzle is moved above the substrate (see JP-A-2007-88381). More specifically, the chemical liquid is supplied from the chemical liquid nozzle onto the front surface of the substrate rotated by the spin shuck, while the chemical liquid nozzle is moved over the substrate.

"In the substrate treatment apparatus of the single substrate treatment type, a chemical liquid heated up to a higher temperature may be used to increase the treatment speed. The chemical liquid supplied from the chemical liquid nozzle has a higher temperature immediately after being supplied onto the front surface of the substrate, but is deprived of heat by the substrate and the ambient environment when flowing over the front surface of the substrate. Thus, the temperature of the chemical liquid is reduced. Therefore, the higher temperature chemical liquid supplied onto the front surface of the substrate from the chemical liquid nozzle has the highest treatment ability at a chemical liquid supply position.

"During the supply of the chemical liquid by the center spouting method, the chemical liquid supplied onto the center portion of the front surface of the substrate receives a centrifugal force generated by the rotation of the substrate to flow toward the peripheral edge on the front surface of the substrate to spread over the entire front surface of the substrate. Where the chemical liquid heated up to a higher temperature is used, the chemical liquid has a relatively high temperature on the center portion of the substrate, and has a relatively low temperature on the other portion of the substrate. This results in variations in treatment efficiency within the front surface of the substrate. That is, the chemical liquid treatment proceeds at a higher treatment rate on the center portion of the front surface of the substrate, and proceeds at a lower treatment rate on the other portion of the front surface of the substrate. As a result, the front surface of the substrate is unevenly treated.

"During the supply of the chemical liquid by the scanning method, on the other hand, the chemical liquid supply position is moved over the front surface of the substrate by the movement of the nozzle. That is, the chemical liquid supply position is moved (scanned) between the rotation center and the peripheral edge of the front surface of the substrate.

"However, the scanning method also fails to evenly perform the chemical liquid treatment on the front surface of the substrate by supplying the chemical liquid heated up to a higher temperature onto the substrate. That is, a movement speed at a point on the front surface of the substrate is increased, as a distance between the point and the rotation center of the substrate increases. Therefore, if the chemical liquid supply rate is constant, the amount of the chemical liquid supplied to a unit area of the front surface of the substrate is reduced as a distance between the chemical liquid supply position and the rotation center increases. This results in variations in treatment efficiency within the front surface of the substrate. More specifically, the chemical liquid treatment proceeds at a relatively high rate on the center portion of the front surface of the substrate, and proceeds at a relatively low rate on the other portion of the front surface of the substrate. Even if the higher temperature chemical liquid is supplied onto the substrate by the scanning method, it is impossible to evenly perform the chemical liquid treatment on the front surface of the substrate."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "It is an object of the present invention to provide a substrate treatment method and a substrate treatment apparatus which ensure that the chemical liquid treatment can be evenly performed on the entire front surface of the substrate.

"A substrate treatment method according to the present invention includes: a higher temperature chemical liquid supplying step of supplying a higher temperature chemical liquid onto a front surface of a substrate in a treatment chamber, the higher temperature chemical liquid having a higher temperature than the treatment chamber; and a rinse liquid supplying step of supplying a rinse liquid onto the front surface of the substrate to rinse away the chemical liquid after the higher temperature chemical liquid supplying step. The rinse liquid supplying step includes a peripheral edge portion treating step of supplying the rinse liquid selectively onto a center portion of the front surface of the substrate so that a chemical liquid treatment is inhibited on the center portion while being allowed to proceed on a peripheral edge portion of the front surface of the substrate; and an entire surface rinsing step of spreading the rinse liquid over the entire front surface of the substrate to replace the chemical liquid with the rinse liquid on the entire front surface of the substrate after the peripheral edge portion treating step. The peripheral edge portion treating step is preferably performed at an initial stage of the rinse liquid supplying step. In the peripheral edge portion treating step, the peripheral edge portion is selectively treated with a part of the chemical liquid remaining on the peripheral edge portion of the front surface of the substrate.

"In the higher temperature chemical liquid supplying step of supplying the higher temperature chemical liquid onto the front surface of the substrate, the chemical liquid treatment proceeds at a relatively high rate on the center portion of the front surface of the substrate, and proceeds at a relatively low rate on the other portion of the front surface of the substrate. Therefore, the chemical liquid treatment is liable to unevenly proceed within the front surface of the substrate.

"According to the inventive method, the peripheral edge portion treating step is performed, for example, at an initial stage of the rinse liquid supplying step performed subsequently to the higher temperature chemical liquid supplying step. In the peripheral edge portion treating step, the rinse liquid is supplied selectively onto the center portion of the front surface of the substrate. By the selective supply of the rinse liquid, the chemical liquid is replaced with the rinse liquid rapidly on the center portion of the front surface of the substrate, but replaced with the rinse liquid at a lower replacement efficiency on the peripheral edge portion of the front surface of the substrate. Therefore, the chemical liquid remains on the peripheral edge portion of the front surface of the substrate. Thus, the chemical liquid treatment is stopped on the center portion of the front surface of the substrate, while the peripheral edge portion of the front surface of the substrate is selectively treated with the remaining chemical liquid. The treatment with the remaining chemical liquid makes up for a delay in the treatment on the peripheral edge portion of the front surface of the substrate. Thus, the chemical liquid treatment can be evenly performed on the entire front surface of the substrate.

"Since the peripheral edge portion treating step is performed during the rinse liquid supplying step, there is no need to additionally perform the step of selectively treating the peripheral edge portion of the front surface of the substrate with the chemical liquid. That is, the chemical liquid treatment can be evenly performed on the front surface of the substrate without prolonging the overall treatment period.

"According to one embodiment of the present invention, the substrate treatment method further includes a chemical liquid treating/rotating step of rotating the substrate at a predetermined first rotation speed, the chemical liquid treating/rotating step being performed in parallel to the higher temperature chemical liquid supplying step. Further, the peripheral edge portion treating step includes a lower speed rotating step of rotating the substrate at a second rotation speed lower than the first rotation speed while supplying the rinse liquid onto the center portion of the front surface of the substrate.

"According to this method, the peripheral edge portion treating step includes the lower speed rotating step, in which the substrate is rotated at a lower rotation speed than in the higher temperature chemical liquid supplying step. In the lower speed rotating step, a very small centrifugal force or virtually no centrifugal force acts on the rinse liquid supplied onto the front surface of the substrate. Therefore, the rinse liquid supplied onto the center portion of the front surface of the substrate remains on the center portion. This makes it possible to supply the rinse liquid selectively onto the center portion of the front surface of the substrate at the initial stage of the rinse liquid supplying step.

"The peripheral edge portion treating step may further include a higher speed rotating step of rotating the substrate at a speed that is generally equal to the first rotation speed, while supplying the rinse liquid onto the center portion of the front surface of the substrate, the higher speed rotating step being performed before the lower speed rotating step.

"According to this method, the higher speed rotating step is performed at the beginning of the rinse liquid supplying step, and the lower speed rotating step is performed after the higher speed rotating step. In the higher speed rotating step, the rinse liquid supplied onto the front surface of the substrate receives a centrifugal force generated by the rotation of the substrate to spread over the front surface of the substrate. In the lower speed rotating step performed after the higher speed rotating step, the rotation speed of the substrate is reduced, so that a very small centrifugal force or virtually no centrifugal force acts on the rinse liquid flowing over the front surface of the substrate. Therefore, the lower speed rotating step is performed when the center portion of the front surface of the substrate is entirely covered with the rinse liquid. Thus, the chemical liquid can remain only on the peripheral edge portion of the front surface of the substrate. This makes it possible to selectively treat only the peripheral edge portion of the front surface of the substrate with the chemical liquid.

"According to another embodiment of the present invention, a rinse liquid supply flow rate at which the rinse liquid is supplied in the peripheral edge portion treating step is lower than a chemical liquid supply flow rate at which the chemical liquid is supplied in the higher temperature chemical liquid supplying step in the substrate treatment method. In this method, the rinse liquid supplied onto the front surface of the substrate at the lower flow rate hardly spreads over the front surface of the substrate, but remains on the center portion of the front surface of the substrate. Thus, the rinse liquid can be supplied selectively onto the center portion of the front surface of the substrate at the initial stage of the rinse liquid supplying step.

"The rinse liquid supplied onto the front surface of the substrate in the rinse liquid supplying step preferably has a higher temperature than the treatment chamber. If an ordinary temperature rinse liquid (e.g., having a temperature substantially equal to the internal ambient temperature of the treatment chamber) is supplied onto the front surface of the substrate in the rinse liquid supplying step, the chemical liquid on the front surface of the substrate is deprived of heat by the rinse liquid at the beginning of the rinse liquid supplying step, resulting in sudden temperature reduction. This reduces the temperature of the chemical liquid remaining on the peripheral edge portion of the front surface of the substrate, thereby reducing the treatment ability of the remaining chemical liquid. Therefore, the higher temperature rinse liquid is supplied onto the front surface of the substrate to suppress the temperature reduction of the chemical liquid remaining on the peripheral edge portion of the front surface of the substrate. Thus, the chemical liquid remaining on the peripheral edge portion of the front surface of the substrate can exhibit a higher treatment ability.

"A substrate treatment apparatus according to the present invention includes: a treatment chamber; a rotation unit which rotates a substrate in the treatment chamber; a higher temperature chemical liquid supplying unit which supplies a higher temperature chemical liquid onto a front surface of the substrate, the higher temperature chemical liquid having a higher temperature than the treatment chamber; a rinse liquid supplying unit which supplies a rinse liquid onto the front surface of the substrate to rinse away the chemical liquid; and a control unit which controls a rotating operation of the rotation unit, a chemical liquid supplying operation of the higher temperature chemical liquid supplying unit and a rinse liquid supplying operation of the rinse liquid supplying unit. The control unit includes: a peripheral edge portion treatment control unit which controls the rotation unit and the rinse liquid supplying unit to selectively supply the rinse liquid onto a center portion of the front surface of the substrate so that a chemical liquid treatment is inhibited on the center portion while being allowed to proceed on a peripheral edge portion of the front surface of the substrate; and an entire surface rinsing control unit which controls the rotation unit and the rinse liquid supplying unit so as to spread the rinse liquid over the entire front surface of the substrate to replace the chemical liquid with the rinse liquid on the entire front surface of the substrate. The control unit supplies the rinse liquid selectively onto the center portion of the front surface of the substrate, for example, at an initial stage of a rinse liquid supplying step of supplying the rinse liquid onto the front surface of the substrate. At this time, the peripheral edge portion of the front surface of the substrate is selectively treated with a part of the chemical liquid remaining on the peripheral edge portion.

"This arrangement provides the same effects as the inventive substrate treatment method described above.

"The foregoing and other objects, features and effects of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings."

For additional information on this patent, see: Nakamura, Kazuki. Substrate Treatment Method and Substrate Treatment Apparatus. U.S. Patent Number 8815111, filed September 8, 2011, and published online on August 26, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8815111.PN.&OS=PN/8815111RS=PN/8815111

Keywords for this news article include: Dainippon Screen Mfg. Co., Dainippon Screen Mfg. Co. Ltd., Electronics, Semiconductor.

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Source: Electronics Newsweekly


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