Projection exposure apparatus, projection exposure method, and method for producing device

Abstract

A projection exposure apparatus transfers a pattern formed on a mask onto a substrate via a projection optical system. The projection exposure apparatus includes electricity removal units which removes electricity from a liquid supplied to a space between the projection optical system and the surface of a substrate. This makes it possible to prevent destruction of the circuit pattern or malfunction of the device which would otherwise caused by charging of the liquid.

Description

CROSS-REFERENCE [0001] This is a Divisional of U.S. patent application Ser. No. 11 / 390,370 filed Mar. 28, 2006, which in turn is a Continuation of International Application No. PCT / JP2004 / 014430 filed Sep. 24, 2004 claiming the conventional priority of Japanese patent Application No. 2003-336888 filed Sep. 29, 2003. The disclosure of each of these prior applications is incorporated herein by reference in its entirety.BACKGROUND OF INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a projection exposure method and an apparatus to be used for transferring a mask pattern onto a photosensitive substrate in the lithography step in order to produce a device including, for example, semiconductor devices, image pickup devices (for example, CCD), liquid crystal display devices, and thin film magnetic heads. In particular, the present invention relates to a projection exposure apparatus and a method using the liquid immersion method. [0004] 2. Description of th...

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Benefits of technology

[0012] The present invention has been made taking the foregoing viewpoints into consideration, an object of which is to provide a projection exposure apparatus which makes it possible to avoid the malfunction of the apparatus and the destruction of the circuit pattern caused by the charging of the liquid to be used for the liquid immersion method. Another object of the present invention is to provide a projection exposure method and a method for producing a device, in which it is possible to avoid the destruction of the circuit pattern and the malfunction of the apparatus.

[0014] According to the projection exposure apparatus of the present invention, the liquid, from which the electricity has been removed, can be supplied to the space between the projection optical system and the substrate. Therefore, it is possible to prevent the circuit pattern formed on the substrate from being destroyed by the electric discharge of the static electricity. Further, it is possible to prevent the electric equipment arranged around the projection optical system and the substrate from malfunctioning due to the electric discharge of the static electricity. In this arrangement, the electricity removal unit may have an electricity-removing filter which is provided in a flow passage of a liquid supply piping for supplying the liquid to the space between the projection optical system and the surface of the substrate, and which is grounded. The electricity-removing filter may be formed of a conductive metal foam or a conductive mesh member. Accordingly, the static electricity, with which the liquid is charged, can be removed from the liquid made to pass through the electricity-removing filter. The exposure apparatus may further comprise a liquid supply unit which supplies the liquid to the space between the projection optical system and the surface of the substrate. In this arrangement, the liquid supply unit may be provided with the electricity removal unit. When the projection exposure apparatus is a step-and-repeat type projection exposure apparatus, the liquid supply unit may supply the liquid in a direction in which the substrate is subjected to stepping. On the other hand, when the projection exposure apparatus is a step-and-scan type projection exposure apparatus, the liquid supply unit may supply the liquid in a scanning direction.

[0018] In this arrangement, the electricity removal unit may have an electrode member which is provided in an optical element of the projection optical system opposed to the substrate. The projection exposure apparatus may have an electricity-removing filter which is provided in at least one of a supply port of a liquid supply piping for supplying the liquid and a recovery port of a liquid recovery piping for recovering the liquid. Accordingly, the electricity can be removed even in a state in which the space between the optical element and the substrate is filled with the liquid. Therefore, the liquid can be prevented from being charged during the exposure and / or during the movement of the substrate.

[0022] Accordingly, the static electricity is removed from the liquid with which the space between the projection optical system and the surface of the substrate is filled. It is possible to avoid the malfunction of the projection exposure apparatus and the destruction of the circuit pattern which is feared to be caused by the electric discharge of the static electricity. The step of removing the electricity may be performed prior to the step of supplying the liquid. In this procedure, the liquid may be made to pass through an electricity-removing filter in the step of supplying the liquid to the space between the projection optical system and the surface of the substrate. The electricity-removing filter may be provided at an end portion of a liquid supply tube for supplying the liquid to the space between the projection optical system and the surface of the substrate. The liquid supplied to the space between the projection optical system and the surface of the substrate may be caused to make contact with a conductive member in the step of removing the electricity from the liquid.

[0024] Accordingly, it is possible to avoid the destruction of the circuit pattern which is feared to be caused by the electric discharge of the static electricity. Therefore, the yield of the device to be produced is improved, and it is possible to avoid the malfunction of the projection exposure apparatus which would be otherwise caused by the electric discharge of the static electricity. Therefore, it is possible to maintain the high processing ability.

Problems solved by technology

However, it is impossible to adjust and match the wafer surface and the image plane with no error at all.

If such a situation is continued as it is, then the depth of focus is excessively decreased, and it is feared that the margin may be insufficient during the exposure operation.

If the liquid, which is charged with the static electricity, is used for the liquid immersion method, it has been feared that the electric discharge may be caused between the liquid and the circuit pattern having been already formed on the wafer, and the circuit pattern may be destroyed.

Further, if the electric discharge is caused between the liquid and any object other than the circuit pattern, it has been feared that the electric equipment, which is arranged around the projection optical system or around the wafer, may malfunction due to the electric noise generated during the electric discharge, and the projection exposure apparatus may cause any error and / or the projection exposure apparatus may be stopped.

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