BLIND-VENTED ELECTRODE

Abstract

A vented electrode that provides a directional stop to prevent energetic particles and secondaries (i.e., secondary electrons, charged particles, photons) generated in the vent channel from reaching into a gap outside of the electrode plate. For example, ventilation is added to at least one electrode, via vented inserts, wherein the vents do not provide a direct line of sight from at least one side of the electrode plate to the other.

Claims

1. A vented electrode, comprising: a plate including a front face and a rear face; the plate additionally including a venting portion and at least one aperture; and the venting portion including a plurality of holes in the front face of the plate and a plurality of holes in the rear face of the plate, wherein no direct line of sight exists between the holes of in the front face and the holes in the back face in at least one direction of: from the front of the plate to the back of the plate or from the back of the plate to the front of the plate.

2. The vented electrode of claim 1, wherein said plate is made from graphite.

3. The vented electrode of claim 1, wherein said venting portion is removably connected to said plate.

4. The vented electrode of claim 1, wherein the venting portion includes at least one blind-venting insert removably fixed to said plate.

5. The vented electrode of claim 4, wherein said at least one blind-venting insert is made from graphite.

6. The vented electrode of claim 4, wherein each hole of said plurality of holes in said front face is connected to one hole of said plurality of holes in said back face by an angled channel.

7. The vented electrode of claim 6, wherein said holes are configured as wells extending into a body of said electrode and said angled channel provides no line of sight in at least one direction from wells in the front of the plate to wells in the back of the plate, or from wells in the back of the plate to wells in the front of the plate.

8. The vented electrode of claim 6, wherein said holes are configured as wells extending into a body of said electrode and said angled channel provides no line of sight from wells in the front of the plate to wells in the back of the plate, and vice versa.

9. The vented electrode of claim 1, wherein said plurality of holes in the front face of the plate are offset relative to said plurality of holes in the rear face of the plate, and said venting portion additionally includes a plurality of vertical channels extending through a body of said venting portion, each vertical channel interconnecting connecting a vertical line of holes in the front face of the plate to a vertical line of holes in the back side of the plate without providing a line of sight in at least one direction from the front of the plate to the back of the plate, or from the back of the plate to the front of the plate.

10. The vented electrode of claim 9, wherein said holes are configured as wells extending into a body of said electrode.

11. The vented electrode of claim 1, wherein the vented electrode is a suppression electrode.

12. The vented electrode of claim 1, wherein the vented electrode is a ground electrode.

13. The vented electrode of claim 1, wherein the vented electrode is an extraction electrode.

14. A blind-venting insert for an electrode, comprising: a body configured to mate with a slot in a plate carrying an electrode; the body including a plurality of holes in the front face of the plate and a plurality of holes in the rear face of the plate, wherein no direct line of sight exists between the holes of in the front face and the holes in the back face in at least one direction of: from the front of the plate to the back of the plate or from the back of the plate to the front of the plate.

15. The blind-venting insert of claim 14, wherein the blind-venting insert is made from graphite.

16. The blind-venting insert of claim 14, wherein each hole of said plurality of holes in said front face is connected to one hole of said plurality of holes in said back face by an angled channel.

17. The blind-venting insert of claim 16, wherein said holes are configured as wells extending into a body of said electrode and said angled channel provides no line of sight in at least one direction from wells in the front of the plate to wells in the back of the plate, or from wells in the back of the plate to wells in the front of the plate.

18. The blind-venting insert of claim 16, wherein said holes are configured as wells extending into a body of said electrode and said angled channel provides no line of sight from wells in the front of the plate to wells in the back of the plate, and vice versa.

19. The blind-venting insert of claim 14, wherein said plurality of holes in the front face of the plate are offset relative to said plurality of holes in the rear face of the plate, and said venting portion additionally includes a plurality of vertical channels extending through a body of said venting portion, each vertical channel interconnecting connecting a vertical line of holes in the front face of the plate to a vertical line of holes in the back side of the plate without providing a line of sight in at least one direction from the front of the plate to the back of the plate, or from the back of the plate to the front of the plate.

20. The vented electrode of claim 19, wherein said holes are configured as wells extending into a body of said electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a partially exploded, perspective view of the suppression and ground grids of an ion implanter in accordance with the prior art;

[0012] FIG. 2 is a simplified Illustration of a front plan view of a vented tungsten extraction grid in accordance with the prior art;

[0013] FIG. 2A is a cross-sectional view, taken along the section line A-A, of the prior art vented tungsten extraction grid of FIG. 2;

[0014] FIG. 3 is a simplified view of the grids in an extraction assembly of an ion implanter, the suppression grid and ground grid, in accordance with one particular embodiment of the present invention;

[0015] FIG. 4 is a simplified, exploded view of a suppression grid and ground grid of an ion implanter in accordance with one particular embodiment of the present invention;

[0016] FIG. 5 is a side, cross-sectional view of a single blind-vented insert, according to a first particular embodiment of the invention;

[0017] FIG. 6 is a perspective view of a double blind-vented insert, according to another particular embodiment of the invention;

[0018] FIG. 6A is a side plan, cross-sectional view of the double blind vented insert of FIG. 6;

[0019] FIG. 7 is a perspective view of a double blind-vented insert, according to a further particular embodiment of the invention;

[0020] FIG. 7A is a perspective view of a cross-section of the double blind vented insert of FIG. 7; and

[0021] FIG. 7B is a side plan, cross-sectional view of the double blind vented insert of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention relates to electrode plates that reduce high voltage glitch rates in accelerators by improving pumping, in particular, by adding blind vent holes in electrode plates. Note that, for purposes of the present application, the terms electrode and grid assembly are used interchangeably, herein. Referring now to FIGS. 3 and 4, there is shown one particular embodiment of a portion of an extraction assembly 100 of an ion implantation system including a suppression grid 110 and a ground grid 160, in accordance with one particular invention. The suppression grid 110 includes a base plate 120 which may be made from graphite, stainless steel or other materials.

[0023] The suppression base plate 120 includes a central slot 130 configured to receive a suppression electrode aperture 140, which is secured thereto using the appropriate fasteners (not shown). In order to promote venting through the suppression grid 110, the base plate 120 additionally includes a plurality of holes or slots 132 that are configured to receive the body of the blind venting inserts 150 (i.e., wherein a flange is mated with a recess in the rear of the plate 120 and secured to the plate 120 via a fastener, not shown). Note that, if desired, blind venting holes could be made directly into the base plate 120; into a single separate piece; and/or into a separate flange, as shown.

[0024] Similarly, in the present preferred embodiment, the ground grid 160 includes a ground plate 170, to which a ground electrode aperture 180 is secured using fasteners (not shown) in the central slot 172. As with the suppression base plate 120, the ground plate 170 includes a plurality of slots 174 (two, in the present example) that are configured to receive the blind venting inserts 190, as described above in connection with the blind venting inserts 150.

[0025] The blind venting inserts 150, 190 are configured to add ventilation on the suppression and ground grids 110, 160, thereby improving vacuum levels in the surrounding areas. The blind venting inserts 150, 190 are, preferably, made of graphite, as well. Inserts 150 may be identical to inserts 190, or may be different, as desired. Each of the inserts 150, 190 includes a plurality of venting channels 152, 192, respectively, which do not have any line of sight from the source side of the suppression grid to the analysis side of the ground grid and/or vice versa.

[0026] Referring now to FIG. 5, there is shown a side, cross-sectional view of one particular embodiment of a one side blind-vented insert 200, which can be used as the inserts 150 and/or 190 of FIGS. 3 and 4. The blind-vented insert 200 includes a body 210 which may be mounted in a separate flange 202, which includes the fastener holes 215. The body 210 has a plurality of blind-vent holes 220 extending therethrough. In the present preferred embodiment, each blind-vent hole 220 includes a well 222 that extends from a hole or opening 228 in the arc side face of the insert 200, into the body 210, offset from a hole or opening 226 in the face on the ground side of the insert 210. In one particular embodiment of the invention, well 222 is cylindrical in shape, although this is not meant to be limiting. An angled channel 224 extends from the opening 226, into the body 210, where it opens into a sidewall of the well 222. In the present embodiment, extracted positive ions strike the negative suppressor plate. Since their trajectory is nearly orthogonal to the surface, the distribution of secondary particles and photons peaks in that direction. Thus, the base of the well 222 of each channel 224 provides a ground/analysis directional stop for this forward peaked distribution of secondary electrons, and, in this sense, there is no line of sight from the source side to the analysis side. Only secondary photons with sufficient energy to penetrate the body 210 can reach the ground grid.

[0027] In contrast, in the present embodiment illustrated in FIG. 5, the opening 226 is aligned with the angled channel 224 to provide a direct line of sight to the opening 228, for secondary electrons generated in the vent channel 224 by incident ions or x-rays from the analysis side of the insert 200 (i.e., arrow 214). Such a line of sight is illustrated by the passage through the body 210 and into the arc side gap of the exemplary electron 230.

[0028] Thus, the embodiment illustrated in FIG. 5 includes a one-sided stop, wherein secondary electrons created by ions and low energy x-rays from the arc gap cannot reach the analysis side, but secondary electrons created by ions or x-rays from the analysis gap can reach the arc gap. Thus, in the present context, the one-sided stop in FIG. 5 is said to have no line of sight for secondaries generated on the source side into the ground/analysis gap.

[0029] Referring now to FIGS. 6-6A, there is illustrated another preferred embodiment of a blind-vented insert 250 that can be used as the blind-vented inserts 150 and/or 190 in FIGS. 3 and 4. The blind-vented insert 250 is similar in most respects to the blind-vented insert 200 (with like reference numbers representing like parts), with the exception that the insert 250 is double blind, having stops in both directions, which are offset (longitudinally, in the present preferred embodiment) relative to one another. More particularly, a plurality of blind-vented channels 224 extend from the arc face 252 of the insert 250 to the ground face 254 of the insert 250. However, the present embodiment preferentially stops ground direction secondaries generated by ion impact from the source, and source direction secondaries generated by ions from the ground side. In this sense, there is no line of sight from the stops in the first face 252 to the second face 254, and vice versa. Rather, wells 222 act as stops on either side of the insert 250, to prevent secondary electrons created by ions or low energy x-rays from either side of the insert 250 from reaching the other side of the insert 250.

[0030] Thus, as illustrated more particularly in FIG. 6A, in the present embodiment, secondary electrons created by ions or low energy photons, depending on the material, from the arc gap side of the blind-vented insert 250 cannot reach the analysis grid and secondary electrons created by ions or low energy photons from the analysis gap cannot reach the plate.

[0031] Referring now to FIGS. 7-7B, there is shown an alternate embodiment of the invention, wherein a blind-vented insert 300 is created using a different mechanical design, wherein a vertical channel 310 is used to interconnect sets of staggered or offset holes 312, 314, instead of an angled channel between the wells, as described in connection with FIGS. 5-6A. More particularly, the vertical channels 310 extend vertically through the body 302 of the insert 300 and intersect with the horizontally aligned, wells or stops 312, 314 extending from each face into, but not through, the body 302 of the insert 300.

[0032] For example, in one exemplary embodiment illustrated in FIGS. 7-7B, a horizontal row of five wells 312 extend through the front face and extend partially into the body 302. Correspondingly, five wells 314 extend through the rear face and partially into the body 302. The distal ends of each of the wells 312, 314 open up into one of the vertical channels 310, however, but not in alignment with one another. Rather, the open rear of the well 312 is in fluid communication with the open rear of the well 314 via the channel 310, but is offset therefrom, thus permitting venting from the combination, but not providing a line of sight through the wells and channel 312, 314, 310 through which secondary electrons generated in the wells 312, 314 can travel. This permits gas to be vented, without permitting secondary electrons generated in the wells 312, 314 from crossing over from one well to the other.

[0033] In the present embodiment, one vertical channel 310 is provided for each vertical column (i.e., vertically aligned plurality) of wells 312, 314. For example, in the embodiment illustrated in FIG. 7, one channel 310 interconnects each of the five columns of wells 312 with one of the five columns of wells 314, of which only one column can be seen in the figures. Note that this is not meant to limit the invention only thereto, as lesser numbers of columns and/or greater numbers may be used without departing from the scope and spirit of the present invention. The configuration illustrated in FIGS. 7-7B provides for double line of sight stop (i.e., from either side of the blind venting insert) for secondary electrons formed in either the wells 312 or the wells 314 from ions or x-rays impinging thereon. In other words, secondary electrons created by ions or x-rays from the arc gap cannot reach the analysis gap, and secondary electrons created by ions or x-rays from the analysis gap cannot reach the arc gap.

[0034] As can be seen from the foregoing exemplary description of the preferred embodiments, the present invention provides a vented electrode that eliminates the line of sight through the vent holes, to stop stray energetic charged particles and some photons from going through the suppressor plate from the extraction gap to the ground plate, and/or from the suppression gap to the source plate. The impact of x-rays or energetic through particles can generate ions that would be accelerated into the suppressor plate, which, in turn, can generate electrons that strike the source or ground electrodes.

[0035] Although discussed herein in connection with suppression and ground electrodes, the present invention can be applied to other types of electrodes, including accelerator and plasma electrodes, without departing from the scope or spirit of the present invention.

[0036] Note that, although both the suppression grid and ground grid have been illustrated in the preferred embodiment as including blind-venting according to the present invention, it should be understood that it is possible only one of the two could include such venting without departing from the scope and spirit of the present invention. Additionally, instead of being incorporated as inserts into the plates, the plates themselves can be vented, as taught herein, and still be within the scope of the present invention.

[0037] It should be understood that this principle can be applied in environments in which particular materials may be preferred for process compatibility. In particular, all or parts of the accelerator grids may be made of preferred conducting materials, such as, Tungsten, graphite, Molybdenum, stainless steel and/or other conducting materials, as desired, without departing from the scope or spirit of the present invention.

[0038] While a preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that within the embodiments certain changes in the detail and construction, as well as the arrangement of the parts, may be made without departing from the principles of the present invention as defined by the appended claims.