Spin chuck with in situ cleaning capability

Abstract

In a method and apparatus for processing wafer-shaped articles, a spin chuck is positioned inside a process chamber. The spin chuck is configured to hold a wafer-shaped article at a predetermined process position. A cover covers the spin chuck and is affixed to or integral with the spin chuck for rotation therewith. The cover has a central opening. A stationary nozzle assembly extends into the process chamber such that a discharge end of the stationary nozzle assembly passes through the central opening of the cover. The nozzle assembly comprises a rinse nozzle configured to direct rinse liquid radially outwardly of the nozzle assembly onto a downwardly-facing surface of the cover.

Claims

1. An apparatus for processing a wafer-shaped article, the apparatus comprising: a process chamber; a spin chuck positioned inside the process chamber, wherein the spin chuck is configured to hold the wafer-shaped article at a predetermined process position; a cover covering the spin chuck and affixed to the spin chuck, wherein the cover rotates with the spin chuck and has a central opening; a stationary nozzle assembly that extends into the process chamber, such that a discharge end of the stationary nozzle assembly passes through the central opening of the cover, wherein the stationary nozzle assembly comprises a rinse nozzle, and wherein the rinse nozzle is configured to direct a rinse liquid radially outwardly of the stationary nozzle assembly onto a downwardly-facing surface of the cover; and an annular lid disposed around the stationary nozzle assembly and configured to close off the process chamber, wherein the annular lid is stationary with the stationary nozzle assembly, wherein the cover extends radially outward from an area between a portion of the annular lid and a portion of the stationary nozzle assembly to the spin chuck, an annular center portion of the cover splits gas received from an annular nozzle of the stationary nozzle assembly, where a first portion of the gas is provided to a second area between the annular lid and the cover and a second portion of the gas is provided to a third area, and the third area is on an opposite side of the cover as the second area.

2. The apparatus of claim 1, wherein the annular nozzle directs the gas over an inner circumferential edge of the cover to the second area and the third area.

3. The apparatus of claim 1, wherein the annular center portion is disposed in the area between the portion of the annular lid and the portion of the stationary nozzle assembly.

4. The apparatus of claim 1, wherein the annular center portion extends axially and away from a radially extending portion of the cover.

5. The apparatus of claim 1, wherein the annular nozzle is disposed radially outward of the rinse nozzle.

6. The apparatus of claim 5, wherein: the stationary nozzle assembly comprises a stationary nozzle head; and the stationary nozzle head is disposed between (i) the rinse nozzle and (ii) the area between the portion of the annular lid and the portion of the stationary nozzle assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other objects, features and advantages of the invention will become more apparent after reading the following detailed description of preferred embodiments of the invention, given with reference to the accompanying drawings, in which:

(2) FIG. 1 is an explanatory cross-sectional side view of an apparatus according to a first embodiment of the invention;

(3) FIG. 2 is a plan view of the outlet cover of the gas showerhead used in the embodiment of FIG. 1;

(4) FIG. 3 is a perspective view, partly in section, showing additional details of the embodiment of FIG. 1; and

(5) FIG. 4 is an enlarged view of the detail IV in FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(6) Referring now to FIG. 1, an apparatus for treating surfaces of wafer-shaped articles according to a first embodiment of the invention comprises a closed process chamber 13, in which is arranged an annular spin chuck 16. Spin chuck 16 is a magnetic rotor that is surrounded by a magnetic stator 17 positioned outside the chamber, so that the magnetic rotor is freely rotating and levitating within the chamber 13 without touching the chamber walls. The chamber 13 is closed at its upper end by lid 14 rigidly secured thereto.

(7) Further structural details of such a magnetic rotor chuck are described, for example, in commonly-owned U.S. Pat. No. 8,646,767.

(8) The annular spin chuck 16 has a circular series of downwardly-depending gripping pins 19, which releasably hold a wafer W during processing. A lower dispense unit 22 is provided so as to supply liquid and/or gas to the side of the wafer W that faces downwardly within chamber 13. A heater 31 is disposed within the chamber 13, so as to heat the wafer W to a desired temperature depending upon the process being performed. Heater 31 preferably comprises a multitude of blue LED lamps, whose radiation output tends to be absorbed preferentially by silicon wafers relative to the components of the chamber 13.

(9) An upper dispense unit comprises an outer gas conduit 27 and an inner liquid conduit 25 arranged coaxially within the outer gas conduit 27. Conduits 25, 27 both traverse the lid 14, and permit liquid and gas to be supplied to the side of the wafer W that faces upwardly within chamber 13. The upper dispense unit also includes a conduit 23 that supplies gas to an annular nozzle 24 in which is formed at least one side nozzle, as will be explained in greater detail below.

(10) The upper dispense unit also includes a conduit 36 that supplies rinse liquid for in situ cleaning, as will also be explained in detail below.

(11) A gas showerhead is delimited at its lower side by an outlet cover 28, which is also shown in plan view in FIG. 2. The outlet cover 28 in this embodiment has a dome shape and comprises a multitude of discharge orifices 29, which permit process gas to pass out of the gas showerhead from the gas distribution chamber 37 to the region adjacent the upwardly facing side of the wafer W. The discharge orifices 29 in this embodiment each have a cross-sectional area in a range from 0.3 to 2.0 mm, preferably from 0.5 to 1.5 mm, and more preferably from 0.7 to 1.2 mm. There are preferably at least 20 orifices 29, more preferably at least 50, still more preferably at least 80, and even more preferably 300.

(12) The outlet dome 28 is rigidly secured to or formed integrally with the spin chuck 16, and therefore rotates along with the spin chuck 16. On the other hand, the conduits 25, 27 are stationarily mounted in the lid 14 of chamber 13, and pass with a slight clearance through a central opening formed in the dome 28.

(13) As shown in FIG. 2, there are a plurality of these orifices 29 in each of a central region and a peripheral region of the dome 28, wherein the central region is defined as being the area within the half-radius 30 of the dome 28, and the peripheral region is defined as being the area outside of the half-radius 30.

(14) Returning to FIG. 1, it will be seen that the gas distribution chamber 37 is supplied with process gas through a process gas supply conduit 34, which in turn communicates with a source of process gas (not shown), which in preferred embodiments is a gas containing ozone.

(15) Additional gas conduits 40 are provided near the outer periphery of chamber 13, and direct a purge gas such as N.sub.2 into the gap defined between the outer periphery of spin chuck 16 and the surrounding cylindrical wall of chamber 13. Gas from nozzles 40 also forms a boundary such that process gas supplied from nozzle 34 is confined within distribution chamber 37.

(16) As shown in FIG. 3, the dome 28 in this embodiment is formed integrally with the spin chuck 16. The lower end of nozzle assembly 21 passes through a central opening in dome 28, and an annular gap 26 is defined between these two components.

(17) The spin chuck 16 also includes the gripping pins 19 described above, as well as needle bearings 18 that urge the pins 19 downwardly so that gear wheels at the upper ends of the pins 19 remain in continuous meshing engagement with the toothed sectors of a common ring gear 15, as described for example in commonly-owned U.S. Pat. No. 8,646,767 and U.S. published patent application no. 2015/0008632.

(18) The clearance or annular gap 26 is necessary to permit the spin chuck 16 with integral dome 28 to rotate relative to the stationary nozzle head 21 that is mounted in the lid 14 of the apparatus.

(19) Nozzle assembly 21 also includes a nozzle block 24, supplied with gas from conduit 23, in which is formed at least one side nozzle 32 which directs gas adjacent this annular gap 26, as shown in FIG. 4. The side nozzle 32 is preferably supplied with an inert gas such as N.sub.2, to control or prevent undesired flow of process gas through gaps 33 and 26.

(20) It will be noted that the bore of nozzles 32 is significantly narrower than the area of the flow paths at the inlet and outlet of nozzles 32. Nozzles 32 are moreover positioned adjacent to yet radially outside of the gap 26. Thus, as inert gas passes through and is discharged from the nozzles 32, the inert gas is accelerated within the nozzles 32, which in turn generates a reduced pressure at the upper end of the annular gap 26, via the Venturi effect. This reduced pressure impedes or prevents any undesired flow of process gas into the gap 26, as might otherwise occur.

(21) Conduit 36 is supplied with a rinse liquid such as deionized water from a rinse liquid supply (not shown). Conduit 36 discharges rinse liquid into an annular recess 38 formed in nozzle assembly 21, surrounding the coaxial nozzles 25, 27. The rinse liquid then flows downwardly along the exterior vertical surface of the nozzle 27, as shown by the downwardly-directed broken line arrows in FIG. 4.

(22) The nozzle pair 25, 27 in this embodiment is formed with a radially outwardly projecting shoulder, which provides a substantially horizontal annular surface 39 on which the rinse liquid impinges as it exits the housing 21 of the nozzle assembly. As the rinse liquid impinges on the annular shoulder surface 39, it is re-directed radially outwardly, as shown by the broken line arrows in FIG. 4.

(23) In particular, the position of the deflecting shoulder surface 39 and its angle of inclination are selected such that the rinse liquid will be sprayed onto the downwardly facing surface of the dome 28, so as to dissolve and rinse away the polymer-based residues that have accumulated on the downwardly facing surface of dome 28 during wafer processing within the chamber 13.

(24) It will be appreciated that the recess 38 and outlet surface 39 need not be annular; they may instead each be formed over only a limited part of the circumference of the nozzle pair 25, 27, because, as the chuck 16 with integrated dome 28 rotates, the rinse liquid will in that case still be applied to the entire downwardly facing surface of the dome 28.

(25) The coaxial surrounding nozzle 27 in this embodiment is also connected to a supply (not shown) of rinse liquid such as deionized water, whereas the central nozzle 25 is supplied with a gas, which may be a process gas or an inert gas for drying of the wafer.

(26) The conduit 36 and nozzle 27 are preferably supplied with rinse liquid independently of one another, so that rinse liquid may be supplied at will through either or both of these elements.

(27) As can be seen in FIG. 4, the deflecting surface 39 preferably meets the adjacent angled surface of the nozzle pair 25, 27 at a sharp angle, which helps prevent rinse liquid from migrating into the gap 26. Moreover, the surfaces of the nozzle assembly that face downwardly into the chamber 13, as well as the downwardly facing surface of the dome 28, are preferably made of a hydrophilic material, or provided with a hydrophilic coating or surface treatment, to aid in the rinsing and drying of those surfaces.

(28) An advantage of the rinsing capability described above is that the downwardly facing surface of the dome 28, which is otherwise difficult to access, can be cleaned without taking the apparatus out of service. Indeed, rinsing of the downwardly facing surface of the dome 28 via conduit 36, recess 38 and deflecting shoulder 39, may be performed even while a wafer W is positioned on the spin chuck 16, and, if desired, simultaneously with rinsing the wafer using the nozzle 27. After the wafer W and/or the downwardly facing surface of the dome 28 have been rinsed in this manner, the rotation of the spin chuck is then increased so as to effect drying of the rinsed surfaces, during which time rinse liquid is not supplied to at least the conduit 36 (in case of drying the dome surface only), and during which time a gas is optionally supplied through the conduit 25.

(29) While the present invention has been described in connection with various preferred embodiments thereof, it is to be understood that those embodiments are provided merely to illustrate the invention, and that the invention is not limited to those embodiments, but rather includes that which is encompassed by the true scope and spirit of the appended claims.