Patent Application
20170162426
1. Field of the Invention
The invention relates generally to an apparatus for processing wafer-shaped articles, such as semiconductor wafers, and more particularly relates to such an apparatus comprising a spin chuck designed to prevent unintended gas flow within the chuck.
2. Description of Related Art
Semiconductor wafers are subjected to various surface treatment processes such as etching, cleaning, polishing and material deposition. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable carrier, as is described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668.
Alternatively, a chuck in the form of a ring rotor adapted to support a wafer may be located within a closed process chamber and driven without physical contact through an active magnetic bearing, as is described for example in International Publication No. WO 2007/101764 and U.S. Pat. No. 6,485,531.
When a stationary nozzle assembly passes through a rotary part of the chuck, a mechanical clearance is necessary. Such clearances, however, can result in unintended gas flows that can adversely affect processing of wafers.
The present inventors have developed an improved apparatus for treatment of wafer-shaped articles, in which a spin chuck is designed to prevent unintended gas flow within the chuck.
Thus, in one aspect, the present invention relates to an apparatus for processing wafer-shaped articles, comprising a process chamber, and a spin chuck positioned inside the process chamber. The spin chuck is configured to hold a wafer-shaped article at a predetermined process position. A plate covers the spin chuck and is affixed to or formed integrally with the spin chuck for rotation therewith, the plate having a central opening. A nozzle assembly extends into the process chamber such that a discharge end of the nozzle assembly passes through the central opening of the plate to define a gap between the plate and the nozzle assembly, the gap extending from an upper inlet end to a lower outlet end. The nozzle assembly comprises at least one side nozzle positioned to direct a gas flow adjacent to the gap and upstream of the lower outlet end, and configured to generate a reduced pressure at a position upstream of the lower outlet end of the gap, thereby to control gas flow through the gap from the upper inlet end toward the lower outlet end.
In preferred embodiments of the apparatus according to the present invention, the plate and an upper part of the process chamber define a gas distribution chamber, and wherein the plate comprises plural openings formed in each of a central and a peripheral region thereof, thereby to supply process gas from the gas distribution chamber to a surface of a wafer-shaped article when held by the spin chuck.
In preferred embodiments of the apparatus according to the present invention, at least one gas supply nozzle is positioned radially outside of the nozzle assembly, the at least one gas supply nozzle supplying process gas to the gas distribution chamber.
In preferred embodiments of the apparatus according to the present invention, the plate is domed such that a central region thereof is positioned farther from a wafer-shaped article when positioned on the spin chuck than a peripheral region thereof.
In preferred embodiments of the apparatus according to the present invention, each of the plural openings has a cross-sectional area in a range from 0.3 to 2.0 mm2, preferably from 0.5 to 1.5 mm2, and more preferably from 0.7 to 1.2 mm2.
In preferred embodiments of the apparatus according to the present invention, the plural openings include at least 20 of the openings, more preferably at least 50 of the openings, and still more preferably at least 80 of the openings.
In preferred embodiments of the apparatus according to the present invention, the at least one side nozzle comprises at least three side nozzles, positioned symmetrically with respect to the gap.
In preferred embodiments of the apparatus according to the present invention, the at least one side nozzle comprises a constricted section having an outlet communicating with a wider section adjacent to and communicating with the upper end of the gap, thereby to generate the reduced pressure via the Venturi effect.
In preferred embodiments of the apparatus according to the present invention, the constricted section is oriented such that a flow path thereof is generally parallel to an axis of rotation of the spin chuck.
In preferred embodiments of the apparatus according to the present invention, the constricted section is oriented such that a flow path thereof extends obliquely to an axis of rotation of the spin chuck, with an inlet of the constricted section being closer to an axis of rotation of the spin chuck than the outlet.
In preferred embodiments of the apparatus according to the present invention, the nozzle assembly comprises a liquid supply conduit and a gas supply conduit, each of the liquid supply conduit and the gas supply conduit opening at the discharge end of the nozzle assembly, at a level below a lower end of the gap.
In preferred embodiments of the apparatus according to the present invention, the central opening of the plate is a circular opening having a diameter of 30-60 mm
In preferred embodiments of the apparatus according to the present invention, the spin chuck comprises a magnetic rotor, the apparatus further comprising a magnetic stator mounted outside of the process chamber and surrounding the magnetic rotor.
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:
Referring now to
Further structural details of such a magnetic rotor chuck are described, for example, in commonly-owned U.S. Pat. No. 8,646,767.
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.
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.
A gas showerhead is delimited at its lower side by an outlet plate 28, which is also shown in plan view in
The outlet plate 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 plate 28.
As shown in
Returning to
Additional gas conduits 40 are provided near the outer periphery of chamber 13, and direct a purge gas such as N2 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.
As shown in
As shown in
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.
The clearance or annular gap 26 is necessary to permit the spin chuck 16 with integral plate 28 to rotate relative to the stationary nozzle head 21 that is mounted in the lid 14 of the apparatus. However, the present inventors have discovered that, in use of such an apparatus, a significant proportion of the flow of process gas is redirected so as to flow not through the openings 29 of the gas showerhead plate 28, but rather through the annular gap 26.
In particular, as shown in
For example, photoresist removal may be performed using a highly reactive gas including ozone, in a closed process chamber at high temperatures. A uniform rate of photoresist removal is required to meet the product specifications. However, with an uncontrolled gas leakage flow from the plate 28 to the annular gap 26, there is a high center peak in the photoresist removal and poor uniformity in the photoresist strip rate.
Turning now to
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 the undesired flow of process gas into the gap 26, as would otherwise occur as shown in
Furthermore, this effect can be tuned by varying the velocity of flow through the nozzles 32, so as to permit a reduced flow of process gas through the annular gap 32, or to prevent process gas from entering the gap 26 altogether, or even to induce a reverse flow of gas upward through the annular gap 26.
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.
