WO1999006163A1

WO1999006163A1 - Apparatus for treating semiconductor wafers

Info

Publication number: WO1999006163A1
Application number: PCT/US1998/009787
Authority: WO
Inventors: Lawrence J. Myland; Christopher F. Mcconnell
Original assignee: Cfmt, Inc.
Priority date: 1997-07-31
Filing date: 1998-05-14
Publication date: 1999-02-11
Also published as: AU7385298A

Abstract

Apparatus for the treatment of substrates (20), such as semiconductor wafers, with a flow of treatment fluid. A flow resistance barrier (24) is positioned in the treatment vessel (12) upstream of the flow of fluid across the wafers (20). The flow resistance barrier (24) is formed as a unitary member with a sealing member (26) that is positioned within the wafer treatment vessel housing walls. The flow resistance barrier provides for a substantially uniform flow of fluids over the wafers (20). The flow resistance barrier (24) is embedded within the sealing member (26), and the sealing member (26) is compressed within a cavity (28) within the vessel, such that collection of contaminants in the sealing member cavity (28) is avoided.

Description

APPARATUS FOR TREATING SEMICONDUCTOR WAFERS BACKGROUND OF THE INVENTION

The present invention relates to semiconductor fabrication. More specifically, the present invention relates to improved apparatus and processes for the enclosed flow-line treatment of substrates with fluids, such as semiconductor wafers and flat panel display.

Apparatus and processes for the treatment of semiconductor wafers are known. One such treatment system is described in U.S. Patent No. 4,633,893 -- McConnell et al . , which is herein incorporated by reference as if set forth in its entirety.

The removal of contaminants from the fluids used during the treatment of semiconductor wafers is of utmost importance. For example, the diffusion step in semiconductor processing is intended to "drive-in" desired dopant atoms into the wafer. Any contaminants left on the wafer surface after pre-diffusion cleaning may also be driven into the wafer and can result in a product having faulty electrical properties. Thus, to achieve acceptable semiconductor yields, it is important that each step in the treatment process be carried out so as to minimize the potential for contamination.

In the treatment process, it is also desirable to provide a resistance barrier to the flow of fluids upstream of the wafers so as to provide a uniform distribution of the flow of aqueous fluids over the surfaces of the semiconductor wafers. In known wafer treatment systems, a screen material is positioned upstream of the wafer to provide a resistance barrier for distributing the flow in a desired pattern across the wafer.

Unfortunately, the screen members used in wafer treatment apparatus are known to cause an accumulation of undesirable contaminants, such as chemicals and particulate matter, due to the arrangement of the screen within the wafer treatment vessel . The screen is fixed into position by the influence of a sealing member, such as an O-ring seal, that is disposed in a cavity in the treatment vessel walls. The edge of the screen material is located at the sealing member cavity prior to insertion of the sealing member into the cavity. As the sealing member is placed into the cavity, the screen is deformed into that cavity under the influence of the sealing member as it is positioned therein. Positioning of the sealing member on top of the deformed screen material results in a gap between the screen and the sealing member. As the treatment fluids flow through the screen in transit to the semiconductor wafer, chemical residue and other particulate matter is wicked into the gap between the screen and the sealing member. The collection of contaminents in the gap between the screen and sealing member eventually results in contamination of the flow of fluids through the screen and onto the wafer during the treatment steps . It is therefore desirable to provide a semiconductor wafer treatment apparatus having a flow restrictive member upstream of the flow of treatment fluids to the wafer wherein the flow restrictive member adequately provides for a desired uniformity of flow at the wafer surface without contaminating the treatment fluid. SUMMARY OF THE INVENTION

Accordingly, it is the general object of the current invention to provide a semiconductor wafer treatment apparatus having a flow restrictive member upstream of the flow of treatment fluids to the wafer wherein the flow restrictive member adequately provides for a desired uniformity of flow at the wafer surface without contaminating the treatment fluid.

Briefly, this object, as well as other objects of the current invention, is accomplished in an apparatus for treating semiconductor wafers with a flow of fluid, wherein the apparatus comprises: (a) a fluid inlet; (b) a vessel in flow communication with the fluid inlet for receiving the flow of fluid from the fluid inlet, the wafers disposed within the vessel and the vessel having a cavity therein; (c) a sealing member positioned in the cavity; (d) a flow resistance barrier disposed in the vessel, wherein a portion of the flow resistance barrier is formed into the sealing member; and (e) means for removing the fluid from the vessel. In preferred embodiments, the flow resistance barrier comprises a chemically resistant woven fabric material or a chemically resistant, perforated polymeric screen material, such as Teflon. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 schematically illustrates a wafer treatment vessel in accordance with the present invention.

Figure 2 shows a blow-up illustration of section A of Figure 1. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Operation of a semiconductor wafer treatment system is set forth in U.S. Patent No. 4,633,893 -- McConnell et al .

Referring to the drawings, there is shown in Figure 1 a portion of a semiconductor wafer treatment system 10 in the vicinity of the wafer treatment vessel 12. Treatment fluids are supplied through piping 14 into the wafer vessel housing 16 during various processing stages, such as a hydrofluoric acid etching stage or a purified water rinsing stage. The flow of treatment fluids is directed from the bottom 15 of the treatment vessel 12 and outlet through the top 17 of the vessel. The flow of treatment fluids expands in the flow expansion area 18 before flowing over the wafer 20, which is held in place in the treatment vessel by wafer support member 22. The present invention is not intended to be limited to the arrangement of the treatment vessel described herein. Other known treatment vessels, such as bench-type fluid processing apparatus can be used in accordance with the present invention.

Prior to treatment of the wafer with a treatment fluid, the fluid flows upward through a flow resistance barrier 24 secured within the wafer vessel housing, upstream of the wafer. The flow resistance barrier 24 can be made of any suitable porous material. Preferred materials for the flow resistance barrier include woven fabric material, to minimize blockage of the flow of fluid at the barrier, and a fiber mesh material wherein the fibers are distributed throughout the flow resistance barrier in a random fiber mesh. Since maunufacturing imperfections in the flow resistance barrier can become dislodged from the barrier over time, thus adding contaminents into the treatment vessel, and can also trap chemicals thereon, thus clogging the barrier, a woven fabric material, which will generally have relatively little manufacturing imperfections, is a most preferred material for the flow resistance barrier. In another preferred embodiment, the flow resistance barrier is a chemical resistant polymeric screen material, with Teflon being the most preferred polymeric material. It is preferred that the flow resistance barrier be chemically resistant to the various chemicals used in the wafer treatment operations so as to avoid chemical degradation of the barrier material . The flow resistance barrier provides a resistance barrier to the flow of fluid into the flow expansion area 18. The material for the flow resistance barrier will be selected to provide a distribution of the flow of fluid onto the wafers in a substantially uniform manner. Where a screen material is used for the flow resistance barrier, the number, shape, size and arrangement of the perforations within the flow resistance barrier can be selected by one skilled in the art to provide a desired level of flow uniformity for the types of fluids used in the wafer treatment process. As described in the above-mentioned U.S. Patent No. 4,633,893, it is preferable that the flow resistance barrier be designed to impart plug flow conditions for the flow of fluid onto the wafer.

It should be noted that the present invention is not intended to be limited to the treatment of semiconductor wafers. For example, the present invention can also be used for treatment of other substrates, such as flat panel display.

Referring to FIG. 2, in order to secure the flow resistance barrier 24 within the wafer vessel housing, the outer edge 25 of the flow resistance barrier is formed into a sealing member 26 such that the flow resistance barrier 24 and the sealing member 26 form a unitary body. In a preferred embodiment, the outer edge 25 of the flow resistance barrier is integrally molded, or embedded, within the sealing member material. The sealing member 26 is positioned in a sealing cavity 28 within the wafer vessel housing walls, upstream of the wafers. The sealing member is fixed into position within the cavity under the influence of the vessel housing on the top surface of the sealing member (not shown in FIG. 2) . The sealing member preferably comprises a compressible material such that when the sealing member is positioned into the sealing cavity, the influence of the vessel housing upon the sealing member causes the sealing member material to deform slightly so as to seal against the shoulders 30 of the vessel without any significant gaps in this region. In this regard, contaminants, such as chemical residue and particulate matter, are substantially precluded by the sealing member from flowing into the cavity 28. Since the flow resistance barrier is formed into the sealing member, and since the flow resistance barrier is disposed at a distance from the vessel housing walls in the area where the sealing member seals against shoulders 30, wicking of chemical residue across the flow resistance barrier and into the sealing cavity is substantially reduced and collection of contaminants in this area is substantially avoided.

Sealing member 26 can be any type of elastomeric material, such as rubber, which, after being compressed within cavity 28, provides for a sealed engagement of the wafer vessel housing walls to prevent leakage of the treatment fluids from the vessel into the sealing member cavity. It is preferable that the sealing member comprise a chemically resistant material. In a preferred embodiment, the sealing member comprises a polymeric material, such as the material sold under the trademark Chemraz, manufactured by Green, Tweed & Co., of Kulpsville, Pennsylvania. The sealing member is preferably a solid material having a substantially circular cross-section, as shown in FIG. 2. The overall configuration of the sealing member, as well as that of the flow resistance barrier, will generally conform to the shape of the inner surface of the treatment vessel housing. The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.

Claims

IN THE CLAIMS :

1. An apparatus for treating at least one substantially planar substrate with a flow of fluid, said apparatus comprising: a) a fluid inlet; b) a vessel in flow communication with said fluid inlet for receiving said flow of fluid from said fluid inlet, said substrate disposed within said vessel, said vessel having a cavity therein; c) a sealing member positioned in said cavity; d) a flow resistance barrier disposed in said vessel, a portion of said flow resistance barrier formed into said sealing member; and e) means for removing said flow of fluid from said vessel .

2. The apparatus according to claim 1, wherein said substrate comprises a semiconductor wafer.

3. The apparatus according to claim 1, wherein said flow resistance barrier comprises a perforated screen material and said sealing member comrpises a polymeric material .

4. The apparatus according to claim 3 , wherein said screen material comprises a chemically resistant, polymeric screen material.

5. The apparatus according to claim 3 , wherein said flow resistance barrier comprises Teflon.

6. The apparatus according to claim 1, wherein said flow resistance barrier comprises a woven fabric material.

7. The apparatus according to claim 1, wherein said sealing member comprises an elastomeric material and said sealing member is compressed within said sealing cavity.

8. An apparatus for treating at least one substantially planar substrate with a flow of fluid, said apparatus comprising: a) a fluid inlet ; b) a vessel in flow communication with said fluid inlet for receiving said flow of fluid from said fluid inlet, said substrate disposed within said vessel, said vessel having a cavity therein; and c) a sealing member and a flow resistance barrier formed as a unitary body disposed in said vessel, said sealing member compressed within said cavity to substantially seal said cavity.

9. The apparatus according to claim 8, wherein said substrate comprises a semiconductor wafer.

10. The apparatus according to claim 8, wherein said flow resistance barrier and said sealing member comprise a chemically resistant material .

11. The apparatus according to claim 8, wherein said sealing member is substantially solid with a circular cross-section.

12. The apparatus according to claim 8, wherein said flow resistance barrier provides for substantially plug flow of the flow of fluid onto said substrate.

13. An apparatus for treating at least one substantially planar substrate with a flow of fluid, said apparatus comprising: a) a fluid inlet; b) receiving means in flow communication with said fluid inlet for receiving said flow of fluid from said fluid inlet, said substrate disposed within said receiving means, said receiving means having a cavity therein; and c) a sealing member and a flow resistance barrier formed as a unitary body disposed in said receiving means, said sealing member compressed within said cavity to substantially seal said cavity.