Source: https://patents.google.com/patent/US20110189613A1/en
Timestamp: 2019-08-22 01:12:44
Document Index: 708128588

Matched Legal Cases: ['Application No. 2003', 'art 70', 'art 80', 'art 70', 'art 80', 'arts 90', 'Application No. 11']

US20110189613A1 - Exposure apparatus, exposure method, and device fabrication method - Google Patents
US20110189613A1
US20110189613A1 US13/064,361 US201113064361A US2011189613A1 US 20110189613 A1 US20110189613 A1 US 20110189613A1 US 201113064361 A US201113064361 A US 201113064361A US 2011189613 A1 US2011189613 A1 US 2011189613A1
US13/064,361
US8272544B2 (en
2006-04-20 Priority to US11/407,210 priority patent/US7932996B2/en
2011-03-21 Application filed by Nikon Corp filed Critical Nikon Corp
2011-03-21 Priority to US13/064,361 priority patent/US8272544B2/en
2011-08-04 Publication of US20110189613A1 publication Critical patent/US20110189613A1/en
2012-09-25 Publication of US8272544B2 publication Critical patent/US8272544B2/en
This is a Divisional Application of U.S. patent application Ser. No. 11/407,210, filed Apr. 20, 2006, which is a Continuation of International Application No. PCT/JP2004/015796, filed Oct. 25, 2004, which claims priority to Japanese Patent Application No. 2003-366914, filed Oct. 28, 2003. The disclosures of the prior applications are hereby incorporated herein by reference in their entirety.
There has been demanded in recent years for higher resolution projection optical systems in order to handle the much higher levels of integration of device patterns. The shorter the exposure-wavelength used and the larger the numerical aperture of the projection optical system, the higher the resolution of the projection optical system. Consequently, the exposure wavelength used in exposure apparatuses has shortened year by year, and the numerical aperture of projection optical systems has increased. Furthermore, the mainstream exposure wavelength is currently the 248 nm assigned to KrF excimer laser, but an even shorter wavelength 193 nm assigned to ArF excimer laser is also being commercialized. In addition, as with resolution, the depth of focus (DOF) is important when performing exposure. The following equations express the resolution R and the depth of focus δ, respectively.
R=k 1˜λ/NA (1)
δ=±k 2˜λ/NA 2 (2)
Incidentally, when the projection optical system and the substrate move relatively to one another, the liquid in the immersion area between the projection optical system and the substrate surface begins to move while being dragged in the direction of the movement of the substrate. In particular, a phenomenon occurs wherein, if the relative movement occurs at high speed in order to improve throughput, then the liquid separates from the lower surface of the projection optical system. Consequently, the separation of the liquid from the lower surface of the projection optical system is prevented by increasing the flow rate of the liquid supplied to the immersion area.
The first aspect is an exposure apparatus that forms an immersion area by supplying a liquid onto a part of a substrate, and forms a prescribed pattern on the substrate through the liquid, wherein a spare immersion area, which is capable of holding part of the liquid on the substrate, is formed at an outer circumference of the immersion area.
In addition, the liquid holding part can also comprise a plurality of projection parts which are disposed substantially annularly.
FIG. 1 is a schematic block diagram that depicts one embodiment of the exposure apparatus according to the present invention. In FIG. 1, an exposure apparatus EX has: a reticle stage RST that supports a reticle (mask) R in which a device pattern is formed; a wafer stage WST that supports a wafer (substrate) W coated with a photoresist, which is a photosensitive material; an illumination optical system IL that illuminates the reticle R supported by the reticle stage RST with exposure light EL; a projection optical system PL that projects the image of a pattern AR of the reticle R, which is illuminated by the exposure light EL, onto the wafer W supported by the wafer stage WST, so as to expose the wafer W; and a control apparatus CONT that performs supervisory control of the operation of the entire exposure apparatus EX.
The projection optical system PL projects the pattern AR of the reticle R onto the wafer W at a prescribed projection magnification β so as to expose the wafer W, and has a plurality of optical elements that includes the optical element 2 provided at the tip part on the wafer W side; in addition, these optical elements are supported by a lens barrel PK. In the present embodiment, the projection optical system PL is a reduction system that has a projection magnification β of, for example, ¼ or ⅕. Furthermore, the projection optical system PL may be an equal magnification system or an enlargement system. In addition, the optical element 2 at the tip part of the projection optical system PL is detachably (replaceably) provided to the lens barrel PK, and the liquid L of the immersion area AR2 contacts the optical element 2.
In addition, the spare immersion area forming member 60 that forms the spare immersion area AR3 is disposed at the outer circumference of the lower end part of the projection optical system PL. An annular groove part 70 and an annular wall part 80 (annular protrusion), which is disposed on the outer side of the groove part 70, are formed on the inner circumferential side of a lower surface 60 a of the spare immersion area forming member 60.
As discussed above, when performing a scanning exposure, the exposure apparatus EX moves the wafer W, via the XY stage 53, with respect to the projection optical system PL, in the +X direction (or the −X direction) at a speed (β˜V (where β is the projection magnification), synchronized to the movement of the reticle R in the −X direction (or +X direction) at a speed V. Furthermore, the scanning exposure and the subsequent stepping operation in order to expose the next shot region are performed repetitively. Namely, by using the so-called step-and-scan system, the scanning exposure process is performed sequentially for each shot region while moving the wafer W.
Thus, when the wafer W is moved in the X and Y directions with respect to the projection optical system PL, the lower surface PLa of the projection optical system PL, i.e., the liquid L disposed in the immersion area AR2, is dragged by the movement of the wafer W and begins to move in the movement direction thereof. In particular, the wafer W moves at a high speed (e.g., approximately 300 mm/s) during the scanning exposure, and the amount of movement of the liquid L therefore becomes large.
As explained above, the lower surface PLa of the projection optical system PL can be continually filled with the liquid L. Furthermore, because the liquid L is pure water, it can be easily obtained in large quantities at semiconductor fabrication plants and the like, and has an advantage in that it does not adversely affect the photoresist on the wafer W, the optical elements (lenses), and the like. In addition, pure water does not adversely affect the environment and has an extremely low impurity content, and can therefore be expected to also serve the function of cleaning the front surface of the wafer W, as well as the lower surface PLa of the projection optical system PL.
In addition, in place of a substantially annular wall part 80, a plurality of projection parts (liquid holding parts) 90, which are substantially annularly disposed, may be formed as depicted in FIG. 7B. This is because the liquid L can be held by its surface tension as long as the spacing between each of the projection parts 90 is sufficiently narrow.
In addition, the present invention can also be adapted to an exposure apparatus that has an exposure stage that can hold. and move a substrate, such as a wafer, to be processed, and a measurement stage, which is equipped with various measuring members, sensors, and the like, as disclosed in Japanese Published Unexamined Patent Application No. 11-135400. As far as is permitted, the disclosure of the abovementioned publication is hereby incorporated by reference.
In addition, if the substrate P is exposed with a fine line-and-space pattern (e.g., a line-and-space of approximately 25 to 50 nm) using, for example, an ArF excimer laser as the exposure light, as well as using a projection optical system PL that has a reduction magnification of approximately ¼, then the structure of a mask M (e.g., the fineness of the pattern and the thickness of the chrome) causes the mask M to act as a polarizing plate due to the wave guide effect, and a larger amount of diffracted light of the S polarized light component (the TE polarized light component) in comparison with the diffracted light of the P polarized light component (the TM polarized light component), which decreases contrast, is emitted from the mask. In this case as well, it is preferable to use the linear polarized light illumination as discussed above; however, even if the mask M is illuminated with random polarized light, a high resolution performance can be obtained by using a projection optical system with a large numerical aperture NA of 0.9 to 1.3. In addition, if exposing a substrate P with an ultrafine line-and-space pattern of a mask M, then there is also a possibility that the P polarized light component (the TM polarized light component) will become greater than the S polarized light component (the TE polarized light component) due to the wire grid effect; however, if conditions are such that the substrate P is exposed with a line-and-space pattern larger than 25 nm, for example, an ArF excimer laser as the exposure light, as well as using a projection optical system that has a reduction magnification of approximately ¼, then a greater quantity of diffracted light of the S polarized light component (the TE polarized light component) than the diffracted light of the P polarized light component (the TM polarized light component) is emitted from the mask, and therefore a high imaging performance can be obtained even in the case of a projection optical system with a large numerical aperture NA of 0.9 to 1.3.
1. An exposure method for exposing a substrate by forming an immersion area by supplying a liquid onto part of a substrate, which includes a projection area of a projection optical system, and projecting a pattern image onto the substrate through the projection optical system and the liquid positioned between the projection optical system and the substrate, the method comprising the step of disposing part of the liquid supplied onto the substrate in a spare immersion area that is formed at an outer circumference of the immersion area.
2. An exposure method according to claim 1, wherein the step of disposing part of the liquid in the spare immersion area is performed prior to exposure of the substrate.
3. An exposure method according to claim 1, further comprising the step of supplying and recovering the liquid to and from the immersion area and the spare immersion area, wherein the amount of the liquid supplied to the immersion area and the spare immersion area is greater than the amount of liquid recovered.
4. A device fabrication method that includes a lithographic process, wherein an exposure method according to claim 1 is used in the lithographic process.
US13/064,361 2003-10-28 2011-03-21 Exposure apparatus, exposure method, and device fabrication method Active US8272544B2 (en)
US11/407,210 Division US7932996B2 (en) 2003-10-28 2006-04-20 Exposure apparatus, exposure method, and device fabrication method
US13/591,583 Continuation US8797506B2 (en) 2003-10-28 2012-08-22 Exposure apparatus, exposure method, and device fabrication method
US20110189613A1 true US20110189613A1 (en) 2011-08-04
US8272544B2 US8272544B2 (en) 2012-09-25