Device for electroless metallization of a target surface of at least one workpiece

Abstract

An assembly for electroless metallization of a target surface (11) of at least one workpiece (10), comprising—a container (13) for receiving an electrolyte solution—an inlet for the electrolyte solution, said inlet arranged in the base (15) of the container (13), wherein the inlet (20) is designed as an inlet port (21) with a diffuser plate (24) comprising inlet openings (25) arranged in concentric circles—an outlet (30) which is arranged on an upper side of the container (13)—a receiving area for holding the at least one workpiece (10), wherein the diffuser plate (24) is formed as a first assembly (31) and a second assembly (32), which is identical to the first assembly, of a respective plurality of inlet openings (25), wherein the assemblies at least partially but not completely overlap, and the inlet (20) has at least two inlet ports (21, 22).

Claims

1. An assembly for electroless metallization of a target surface (11) of at least one workpiece (10), comprising: a container (13) for receiving an electrolyte solution; an inlet for the electrolyte solution, said inlet arranged in a base (15) of the container (13), wherein a diffuser plate (24) with a plurality of inlet openings (25) is arranged on an inside of the container above the inlet (20); an outlet (30) arranged on an upper side of the container (13); and a receiving area for holding the at least one workpiece (10), wherein the at least one workpiece (10) is arranged vertically upright in the receiving area, wherein the plurality of inlet openings (25) formed through the diffuser plate (24) are evenly divided into a first assembly (31) and a second assembly (32), which is identical to the first assembly, wherein the first assembly (31) and the second assembly (32) partially overlap, wherein each of the first assembly (31) and the second assembly (32) has a circular configuration, with the plurality of inlet openings (25) of each of the first assembly (31) and the second assembly (32) being arranged in a pattern of concentric circles, and wherein the inlet (20) comprises at least a first inlet port (22) and a second inlet port (23), wherein the first inlet port (22) and the second inlet port (23) are coaxially aligned with respective centers of the first assembly (31) and the second assembly (32), and wherein the diffuser plate (24) comprises a first baffle region located centrally within the first assembly (31) and a second baffle region located centrally within the second assembly (32), the first and second baffle regions being solid and free of the inlet openings (25), such that the first inlet port (22) and the second inlet port (23) are not positioned directly beneath the plurality of openings (25).

2. The assembly according to claim 1, wherein the first assembly (31) and the second assembly (32) are arranged along a longitudinal axis (L) of the container (13).

3. The assembly according to claim 2, wherein the diffuser plate (24) is arranged centered on the base of the container (13).

4. The assembly according to claim 3, wherein the inlet (20) comprises at least the first inlet port (22), the second inlet port (23) and a third inlet port (21).

5. The assembly according to claim 4, wherein the third inlet port (21) is aligned centered relative to the diffuser plate (24), and the first inlet port (22) and the second inlet port (23) are aligned with the third inlet port (21).

6. The assembly according to claim 5, wherein the first inlet port (22) and the second inlet port (23) have a cross-sectional surface (A.sub.Z) of 45% of a cross-section of the third inlet port (21).

7. The assembly according to claim 1, wherein all of the inlet openings (25) have an identical diameter (d).

8. The assembly according to claim 1, wherein a surface of the diffuser plate (24) covers at least 95% of a base surface (A.sub.B) of the base of the container (13).

9. The assembly according to claim 1, wherein the first, second and third inlet ports (22, 23, 21) have an identical cross-sectional surface (A.sub.Z).

10. The assembly according to claim 1, wherein at least one pump is provided for the inlet.

11. The assembly according to claim 1, wherein a diameter of each of the inlet openings of each of the first assembly (31) and the second assembly (32) increases as a radius r measured from a center of a corresponding one of the first and second assemblies increases.

12. The assembly according to claim 11, wherein the diameter of each of the inlet openings is at least 0.15 cm.

13. The assembly according to claim 1, wherein the diffuser plate (24) has at least 248 inlet openings (25).

14. The assembly according to claim 13, wherein the plurality of inlet openings (25) span 3% of a total surface area of the diffuser plate (24).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic sectional view of an assembly for electro-less metallization according to the present invention;

(2) FIG. 2 is a perspective view of the assembly from FIG. 1;

(3) FIG. 3 is a schematic top view of a diffuser plate as it is used in an assembly according to FIGS. 1 and 2;

(4) FIG. 4A illustrates an exemplary embodiment of a diffuser plate from FIG. 3, in a view from below;

(5) FIG. 4B illustrates an arrangement of three inlet ports relative to the diffuser plate from FIG. 4a;

(6) FIG. 5 illustrates the diffuser plate from FIG. 4A in a perspective view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) FIG. 1 shows a schematic sectional view of an assembly for electroless metallization according to the present invention.

(8) FIG. 1 shows a longitudinal section of a container 13, in which a plurality of workpieces 10 to be coated, for example semiconductor wafers, are arranged vertically upright in a so-called wafer carrier. In the present exemplary embodiment, a first inlet port 21, a second inlet port 22, as well as a third inlet port 23 are arranged in a base 15 of the container 13 along the longitudinal axis and centrally in the transverse direction. An electrolyte solution for electroless metallization of the workpieces 10 arranged in the container 13 can be supplied to the container 13 via the inlet ports 21, 22, 23. In order to achieve sufficient homogeneity when coating the workpieces 10, a diffuser 24, which is designed as a diffuser plate in this case, is arranged between the inlet ports 21, 22, 23 and the section of the container 13 in which the workpieces 10 are arranged.

(9) To this end, the diffuser plate 24 is arranged in a lower fourth of the container 13 such that the diffuser plate is arranged between the workpieces 10 and an inlet 20, which is formed by the inlet ports 21, 22, 23, and thus a distribution of the medium supplied via the inlet 20 is ensured. Because the electrolyte solution, which is used for the metallization of the workpieces 10 in this case, is continuously recirculated during implementation of the metallization process, i.e. the electrolyte solution, which flows out of the container 13 via an upper edge of the container 13, which forms an outlet 30 in this case, is captured and then is supplied back to the container 13 via the inlet 20 arranged on the base, the diffuser plate 24 ensures a distribution of concentration that is as homogenous as possible of the reactants contained in the electrolyte solution to the extent that homogenous metal deposition takes place.

(10) FIG. 2 shows the assembly, which is only shown schematically in FIG. 1, in a more detailed perspective view.

(11) It can be seen that the container 13, which is designed as a quartz glass container in this exemplary embodiment, is substantially in the shape of a cube and is surrounded by an overflow container 14 for capturing the medium flowing over the upper edge, which is formed as an outlet 30. The overflow container 14 has different connection ports, which are formed for guiding the electrolyte solution or as connections for cleaning the assembly. Furthermore, various attachment parts can be seen on the overflow container 14, which are designed, for example, for holding or implementing various retainers for the workpieces 10.

(12) Finally, FIG. 3 shows a schematic top view of a diffuser plate 24 as it can be used in an assembly according to FIGS. 1 and 2.

(13) In the present exemplary embodiment, the diffuser plate 24 is substantially shaped as a rectangle, wherein, in the view shown in FIG. 3, a first assembly 31 and a second assembly 32 are obvious, which are designed as overlapping circles in sections. The circles in the middle points M.sub.1, M.sub.2 of the two assemblies 31, 32 are arranged on the longitudinal axis L, which corresponds to an axis of symmetry, of the diffuser plate 24, extending in the longitudinal direction, to the extent that the two assemblies 31, 32 overlap in sections, wherein a totality of the assemblies 31, 32 is arranged centrally on the diffuser plate 24 in the longitudinal direction.

(14) In addition, FIG. 3 shows the arrangement of the inlet ports 21, 22, 23 relative to the assemblies 31, 32. In the exemplary embodiment shown, the second inlet port 22 is aligned concentric to the first assembly 31 and the third inlet port 23 is aligned concentric to the second assembly 32. The first inlet port 21, just as the two other inlet ports 22, 23, is arranged along the longitudinal axis L in this case, precisely between the second inlet port 22 and the third inlet port 23. Thus, the first inlet port 21 is arranged equidistant to the two other respective inlet ports.

(15) FIG. 4A shows a potential embodiment of a diffuser plate 24, as is only shown schematically in FIG. 3, In this exemplary embodiment, the diffuser plate 24 has a plurality of inlet openings 25, which are arranged in concentric circles. In order to achieve an optimum distribution of the medium supplied via the inlet ports 21, 22, 23, the first assembly 31 and the second assembly 32 have centrally arranged baffle plates 27 in the exemplary embodiment shown in FIG. 4A, in which no inlet openings 25 are arranged in the area of the baffle plates. The baffle plates are thus formed by an area implemented free of openings, starting from the respective middle point of the assembly 31, 32 and proceeding to a first radius r.sub.1. The baffle plates 27 provide an improved distribution of the medium supplied via the second inlet port 22 and the third inlet port 23.

(16) The view of the diffuser plate 24 shown in FIG. 4A further shows that the diffuser plate 24 is chamfered about the circumference. This means that, upon the placement of the diffuser plate 24 in the container 13, a self-centering of the diffuser plate relative to the container 13 is achieved on correspondingly formed overlays through the circulating phase. FIG. 4A further shows that the inlet openings 25 can have different diameters. In the exemplary embodiment shown, the inlet openings 25 of the two innermost circles of inlet openings 25 are formed with a smaller diameter and thus with less flow cross-section in the assemblies 31, 32. This can also be used to adjust the concentration distribution within the container 13.

(17) FIG. 4B, when viewed together with FIG. 4A, shows the inlet ports 21, 22, 23 as well as the alignment thereof relative to the diffuser plate 24.

(18) FIG. 5 shows the diffuser plate 24 from FIG. 4A in a perspective view. FIG. 5 shows a perspective view from below, in which the circulating phase of the diffuser plate 24 can be easily seen. Furthermore, FIGS. 4A and 5 show that the first assembly 31 and the second assembly 32 are guided up to the edge of the diffuser plate 24 in the direction of the longitudinal axis L. In the transverse direction, i.e. in a direction at a right angle to the longitudinal axis L, the assemblies 31, 32 likewise reach the edge of the diffuser plate—the chamfered area has been removed—wherein the underlying circular shape of the assemblies 31, 32 would actually reach beyond the edge of the diffuser plate 24. As previously shown, the inlet openings 25 are arranged in concentric circles.

LIST OF REFERENCE NUMERALS

(19) 10 Workpiece/wafer 11 Target surfaces 13 Container 14 Overflow container 15 Base 20 Inlet 21 First inlet port 22 Second inlet port 23 Third inlet port 24 Diffuser 25 Inlet openings 27 Baffle plates 30 Outlet 31 First assembly 32 Second assembly 90 Inlet 91 Inlet port L Longitudinal axis d Diameter A.sub.D Surface A.sub.B Base surface A.sub.Z Cross-sectional surface