ION IMPLANTATION DEVICE WITH ENERGY FILTER HAVING ADDITIONAL THERMAL ENERGY DISSIPATION SURFACE AREA

Abstract

An ion implantation device (20) comprising an energy filter (25), wherein the energy filter (25) has a thermal energy dissipation surface area, wherein the energy filter (25) comprises a membrane with a first surface and a second surface disposed opposite to the first surface, the first surface being a structured surface.

Claims

1. An ion implantation device (20) comprising an energy filter (25), wherein the energy filter (25) has a thermal energy dissipation surface area, wherein the energy filter (25) comprises a membrane with a first surface and a second surface disposed opposite to the first surface, the first surface being a structured surface.

2. The ion implantation device (20) of claim 1, wherein the first structured surface or the second surface has a microstructure imposed thereon and forms an additional thermal energy dissipation surface area, wherein the spatial dimensions of the microstructure are between 3-5% of the spatial dimensions of a structure on the first structured surface.

3. The ion implantation device (20) of claim 2, wherein the microstructure has one of a randomly arranged structure or a structure with a triangular cross-section.

4. The ion implantation device (20) of claim 1, wherein the energy filter (25) comprises a plurality of membranes (400a-c) with a further membrane (400a-c) disposed at a distance from a first membrane (400a-c).

5. The ion implantation device (20) of claim 4, further comprising an ion beam source (5), a substrate material (30) and a plurality of membranes (400a-c) disposed between the ion beam source (5) and the substrate material (30).

6. The ion implantation device (20) of claim 4, further comprising positioning elements (430) to move the spacing between ones of the plurality of membranes (400a-c).

7. The ion implantation device (20) of claim 4, further comprising a collimator (420) disposed between one of the first membrane (400a-c) or the further membrane (400a-c) and the substrate material (30).

8. The ion implantation device (20) of claim 1, wherein the structure of the first surface is one of a structure with a triangular cross-section or is pyramid shaped.

9. The ion implantation device (20) of claim 1, wherein the energy filter (25) is made of a silicon membrane.

10. The ion implantation device (20) of claim 1, further comprising a housing (410; 510), wherein the energy filter (25) is mounted in the housing (410; 510).

11. The ion implantation device (20) of claim 10, wherein the housing (510) further comprises a plurality of conduits (510) for transferring cooling fluid (530).

12. The ion implantation device (20) of claim 10, wherein the housing (410, 510) further comprises a plurality of absorber elements (540) in thermal contact with the housing (510) blocking for visible and infra-red light.

13. The ion implantation device (20) of claim 1, further comprising a filter frame (27), wherein the energy filter (25) is held by the filter frame (27).

14. A housing (510) for an energy filter (25), wherein the housing (510) comprises a plurality of conduits (510) for transferring cooling fluid (530).

15. The ion implantation device (20) of claim 5, further comprising positioning elements (430) to move the spacing between ones of the plurality of membranes (400a-c).

16. The ion implantation device (20) of claim 12, wherein the housing (410, 510) further comprises a plurality of absorber elements (540) in thermal contact with the housing (510) blocking for visible and infra-red light.

Description

DESCRIPTION OF THE FIGURES

[0023] FIG. 1 shows the principle of the ion implantation device with an energy filter as known in the prior art.

[0024] FIG. 2 shows a structure of the ion implantation device with the energy filter.

[0025] FIG. 3 shows the energy filter with a microstructure.

[0026] FIG. 4 shows a plurality of membranes in the energy filter as well as open/closed collimation devices.

[0027] FIG. 5 shows a cooling system for the energy filter.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The invention will now be described on the basis of the drawings. It will be understood that the aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect of the invention can be combined with a feature of a different aspect or aspects of the invention.

[0029] FIG. 3 shows a structure for the membrane of the energy filter 25 according to one aspect of this document. FIG. 3A shows the structured membrane for the energy filter 25 with a triangular cross-section, as known in the art. FIG. 3B shows a microstructure on a surface on one side of the membrane 25 in the energy filter 25 and FIG. 3C shows a microstructure on a surface of both sides of the energy filter 25. In other words, the energy filter 25 has a membrane which in addition to its regular triangular cross-sectional form has an additional microstructure on one or more surfaces.

[0030] In the non-limiting example shown in FIG. 3, the height h of the triangular form is 16 .Math.m and the spacing s is 20 .Math.m. The energy filter 25 can be made with different dimensions, for example the height can be between 1 .Math.m and 200 .Math.m and the spacing between 1 .Math.m and 400 .Math.m.

[0031] The microstructure will affect the energy profile of the ion beams 10 passing through the energy filter 25. Assuming, however, that the energy profile has a tolerance of 3-5%, then the microstructure can have a height (marked as mh on the figure, but not to scale) of 3-5% of the value of the height h and the spacing (marked as ms on the figure, but not to scale) can be 3-5% of the distance of the spacing s. It will, of course, be appreciated that the change in the energy profile will be affected by the microstructure on both sides of the energy filter 20.

[0032] The microstructure is created by etching the energy filter 20 from a bulk material or by depositing material on a substrate. There are a number of methods known in the art. For example, a mask can be created on the substate using patterning techniques such as photolithography, e-beam lithography, or laser-beam lithography. The mask is made of a photoresist, silicon dioxide, silicon carbide, chromium, or other materials. Wet chemical etching techniques use, for example, potassium hydroxide, TMAH (tetramethylammonium hydroxide), and other anisotropic etching solutions, plasma-etching techniques, and ion-beam etching.

[0033] Self-masking etching techniques can also be used, such as reactive ion etching in a strongly polymerizing process regime or using a potassium hydroxide solution with an additive such as isopropanol.

[0034] Self-masking deposition techniques, such as chemical vapor deposition in a selective deposition mode or atomic layer deposition mode can also be used.

[0035] Sequential deposition or etching of layers, without masking, is also known. This used femto laser ablation or focused ion beam deposition or removal of material.

[0036] It will be appreciated that the creation of the microstructure can be accomplished by mechanically roughing the surface of the surface membrane 25, adding an additional thin layer of materials such as silicon or carbon, or using other techniques such as laser ablation.

[0037] It is possible that the structure of the membrane of the energy filter 25 has a different structure and is not in the form with a triangular cross-section. For example, the energy filter 25 could be formed of a series of pyramids, as known in the art. The microstructure would then be placed on the surface of the pyramids.

[0038] The effect of the microstructure is to provide a greater surface area to the membrane of the energy filter 25 which enables a greater degree of thermal cooling of the energy filter 25 because of the greater surface area.

[0039] A further aspect of the invention is shown in FIGS. 4A and 4B in which the energy filter 25 comprises a plurality of membranes 400a-c mounted in a plurality of frames 27 in a housing 410. The housing 410 can be made of steel with an inner coating of silicon carbide or another carbon material. The inner coating is used to reduce or eliminate contamination of the semiconductor substrates. FIG. 4A shows a plurality of multilayers of the energy filters 25 and FIG. 4B shows energy filters 25 with the triangular cross-sectional film. The membranes of the energy filters 25 could also include the microstructures as shown in FIG. 3.

[0040] The plurality of membranes 400a-c forming the energy filter 25 are arranged in the housing 410. The plurality of membranes 400a-c can be moved in a direction along the direction of the ion beam 10 within the housing 410 to change the spacing between the individual ones of the membranes 400a-c and between the membranes 400a-c and the substrate material 30. The spacing can be changed both in the vertical and horizontal directions using positioning elements 430, for example, piezoelectric elements or micromotors.

[0041] The arrangement of FIGS. 4A and 4B also includes a (optional) collimator 420 to collimate the ion beam 10 after the ion beam 10 has passed through the plurality of the membranes 400a-c. The collimator 420 can be open or closed at the ends. It will be appreciated that each ones of the plurality of membranes 400a-c each absorb part of the energy of the passing ion beam 10 and thus the membranes 400a-c from which the energy filter 25 is made absorb less energy than a single one of the membranes 400a, 400b or 400c. The plurality of membranes 400a-c cool through thermal emission.

[0042] The arrangement of the energy filter 25 shown in FIGS. 4A and 4B also enable different depth profiles to be created for the ions penetrating the substrate material 30. The plurality of membranes 400a-c are shown in FIGS. 4A and 4B as being similar, but each of the plurality of membranes 400a-c can have a different profile if required.

[0043] Three membranes 400a-c are shown in FIG. 4, but it will be appreciated that the number of membranes 400a-c can be larger. An increase in the number of membranes 400a-c will enable more energy to be dissipated. Suppose the maximum amount of energy that can be dissipated in a single one of the membranes 400a-c is 1.6 W/cm.sup.2 to avoid damage. If the ion beam 10 has an energy of 10 MeV and it is assumed that 50% of the energy is needed to create the deposition pattern in substrate material 30, then the ion current in the ion beam 10 is around 0.23 .Math.A/cm.sup.2. With five of the membranes 400a-c it is assumed that each one of the membranes 400a-c can absorb the same amount of energy, then the maximum ion current will be 1.6 .Math.A/cm.sup.2.

[0044] A further aspect of the invention is shown in FIG. 5 in which an energy filter 25 is mounted in a cooling housing 500. The cooling housing 500 has one or more conduits 510 in the walls 520 of the cooling housing 500 through which a cooling fluid 530. The cooling fluid 530 is, for example, water. The thermal radiation radiated from the energy filter 25 is absorbed by the walls 520 and the heat is then dissipated though the cooling fluid 520.

[0045] In a further aspect, the insides of the walls 520 can have absorber elements 540 of, for example, silicon or carbon-based materials and have thicknesses in the micrometer to millimeter region. The absorber elements 540 absorb the radiated thermal energy from the energy filter 25.

TABLE-US-00001 REFERENCE NUMERALS 5 Ion beam source 10 Ion Beam 20 Ion implementation device 21 Silicon layer 22 Silicon dioxide layer 23 Bulk silicon 25 Energy Filter 27 Filter Frame 30 Substrate material 400a-c Membranes 410 Housing 420 Collimator 430 Positioning elements 500 Cooling Housing 510 Conduits 520 Walls 530 Cooling fluid 540 Absorber elements