US 7652264 B2
A filament member configured to discharge thermions may be employed in an ion source of an ion implantation apparatus. A filament member may include an anode disposed around a central portion of the filament member, a cathode disposed around a periphery of the filament and/or enclosing the anode, and at least one conductive path disposed between the anode and the cathode to discharge the thermions.
1. A filament member, comprising:
an anode disposed around a central portion of the filament member;
a cathode disposed around a periphery of the filament member and configured to enclose the anode; and
at least one conductive path disposed between the anode and the cathode to discharge thermions, wherein at least two of the cathode, the anode, and the at least one conductive path are coplanar.
2. The filament member as set forth in
3. The filament member as set forth in
4. The filament member as set forth in
5. The filament member as set forth in
6. The filament member as set forth in
7. The filament member as set forth in
8. The filament member as set forth in
9. The filament member as set forth in
10. The filament member as set forth in
11. An ion source comprising:
the filament member as set forth in
an arc chamber including an inflow port configured to introduce source gas and a beam outlet configured to externally emit ions generated in the arc chamber;
an arc power supply to supply power to the arc chamber; and
a filament power source to supply power to the filament member.
12. The ion source as set forth in
13. The ion source as set forth in
14. The filament member as set forth in
15. The filament member as set forth in
16. An ion implantation apparatus comprising:
the ion source as set forth in
an analyzer configured to select ions from the ion source; and
an accelerator configured to accelerate the selected ions into a wafer.
17. The ion implantation apparatus as set forth in
a concentrator configured to preventing the ions from spreading;
a scanner configured to control a vertical direction of the ions; and
an end station configured to hold the wafer for ion injection.
A claim of priority is made under 35 U.S.C. § 119 to Korean Patent Application 2005-94486 filed on Oct. 7, 2005, the entire contents of which are hereby incorporated by reference.
Example embodiments disclosed herein may relate to apparatuses for use in fabricating semiconductor devices. In particular, example embodiments disclosed herein may relate to a filament member, an ion source and an ion implantation apparatus.
Ion implantation is a process of injecting impurities, for example, P-type or N-type impurities, for example boron (B), aluminum (Al), and indium (In), or, antimony (Sb), phosphorous (P), and arsenic (As), which may be controlled in a plasma ionic condition, into a pure silicon (Si) wafer to produce a device with required conductivity and resistivity. Ion implantation techniques have been widely used to manufacture semiconductor devices, because controlling the concentration of impurities injected into a wafer may be easier.
An apparatus used for ion implantation may have an ion source for generating ion beams.
The filament 940 may be coiled as illustrated in
Positive ions generated in a region adjacent to the filament 940 may be incident on the filament 940. Those positive ions may collide against the filament 940, which may cause a sputtering etch effect on the filament 940. The sputtering etch effect may degrade the filament 940, resulting in a short, and may shorten the life span and/or endurance of the filament 940. Degradation of the filament 940 also may cause an increase in preventive maintenance cost and/or repair.
The sputtering etch effect may be higher when the positive ions are incident on the surface of the filament 940 at an angle of around 30° through 60°. Accordingly, the filament 940, may be shaped as a wire, for example a pig's tail, as shown in
Further, as aforementioned, because the thermions emitted from the filament 940 may be more abundant around the cathode, more positive ions may be generated in regions adjacent to the cathode. Thus, positive ions applied onto the filament 940 may increase around the cathode, increasing the sputtering etch effect at those regions thereof.
Therefore, if the filament is shorted due to the sputtering etching effect, the ion implantation equipment may have to be shut off to replace the shorted filament.
Moreover, using the conventional filament, electrons emitted from the filament may partially discharge and collide with a sidewall of the arc chamber, thereby damaging the arc chamber.
Example embodiments may be directed to a filament member capable of more uniformly emitting thermions.
Example embodiments may be directed to a filament member having a structure with an increased lifetime by lowering a sputtering etch effect.
Example embodiment may be directed to a filament member capable of continuous operation even when one or more current paths may be shorted by a sputtering etch effect.
Example embodiment may be directed to a filament member capable of preventing electrons, which may be discharged from the filament member, from colliding with a sidewall of an arc chamber in an ion source.
In an example embodiment, a filament member configured to discharge thermions may include an anode disposed around a central portion of the filament member, a cathode disposed around a periphery of the filament and/or configured to enclose the anode, and at least one conductive path disposed between the anode and the cathode to discharge the thermions.
Non-limiting and non-exhaustive example embodiments will be described with reference to the following drawings, wherein like reference numerals may refer to like parts throughout the various drawings unless otherwise specified. In the drawings:
Example embodiments will be described below in more detail with reference to the accompanying drawings. Example embodiments may, however, be embodied in different forms and should not be constructed as limited to example embodiments set forth herein. Rather, example embodiments are provided so that this disclosure will be thorough, and will convey the scope of the example embodiments to those skilled in the art.
It will be understood that when an element or layer is referred to as being “on”, “connected to” or “coupled to” another element or layer, it may be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Example embodiments may be described herein with reference to cross-section illustrations that may be schematic illustrations of idealized embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, the example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the drawings are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the example embodiments.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Hereinafter, example embodiments will be described with reference to
With reference to
Ions may be generated from the ion source 10. Ions with sufficient atomic weights required for implanting a wafer therein may be selected. The ions selected by the analyzer 20 may be accelerated up to an energy level capable of injecting them into a wafer to a desired depth by way of the accelerator 30. Neutral atoms may be ionized to allow positive ions to move in a cluster, and ion beams may be focused on the concentrator 40 to prevent the ion beams from spreading away by a repulsive force thereof. To more uniformly distribute the ion beams over the wafer, a progressing direction, for example, in the vertical direction, of the ion beams may be controlled by the scanner 50 and thereby the ions may be injected into the wafer at the end station 60.
The arc chamber 100 may be rectangular shaped and include a first sidewall 120, a second sidewall 140, a third sidewall 160, and a fourth sidewall 180. Because the arc chamber 100 is a three-dimensional chamber, it should be noted that the arc chamber 100 may also have a fifth sidewall (not shown) and a sixth sidewall (not shown). The first sidewall 120 may be opposite to the second sidewall 140, and the third sidewall 160 may be opposite to the fourth sidewall 180. The third and fourth sidewalls 160 and 180 may be disposed vertical to the first and second sidewalls 120 and 140. An inflow port 122 may be located on the first sidewall 120 to introduce source gas into the arc chamber 100. At the second sidewall 140, a beam outlet 142 may be used to emit positive ions generated within the arc chamber 100. The inflow port 122 may be formed in a circular shape and the outlet 142 may be formed in a slit shape. The arc chamber 100 may be supplied with a positive voltage from an arc power supply 484.
The filament member 200 and the repeller 300 may be arranged in the arc chamber 100 opposite to each other. The filament member 200 may be disposed near and in parallel with the third sidewall 160. The repeller 300 may be disposed near and in parallel with the fourth sidewall 180. The filament member 200 may discharge thermions into the arc chamber 100 to ionize source gas into positive ions and electrons within the arc chamber 100.
The repeller 300 may be supplied with a negative power voltage. The repeller 300 may force non-reacted thermions to move toward the source gas. The filament member 200 may be supported by a filament fixing block 420, and the repeller 300 may be supported by a repeller fixing block 440. The filament fixing block 420 may be made of a dielectric material. The filament fixing block 420 may penetrate the third sidewall 160 and insulate the filament member 200 from the arc chamber 100. A conductive projection may include an anode conductive projection 422A and a cathode conductive projection 422B and may be provided to contact the filament member 200. The anode conductive projection 422A and a cathode conductive projection 422B may be supplied with a filament current from a filament power source 482. The repeller fixing block 440 may be made of a dielectric material. The repeller fixing block 440 may penetrate the fourth sidewall 180 and insulate the repeller 300 from the arc chamber 100. A conductive projection 442 may be provided with the repeller fixing block 440 to contact the repeller 300.
The filament member 200 illustrated in
According to an example embodiment, the anode 220 may be formed in a pattern of a circle (an example shape), and the cathode 240 may be in a ring-shape (also, an example shape). The anode 220 and the cathode 240 may be centered near the same point. The anode 220 and the cathode 240 should be of sufficient diameter size and width to prevent emission of thermions from the anode 220 and cathode 240. The conductive paths 260 may be designed to be narrower in width relative to those of the anode 220 and cathode 240.
According to other example embodiments the positions of the anode 220 and the cathode 240 may be reversed, namely, the anode 220 (with its varying shapes) may be disposed at a peripheral edge of the cathode 240.
The anode 220 may be connected to the conductive projection 422A, which may be coupled to the positive electrode of the filament power source 482. The cathode 240 may be connected to the conductive projection 422 b, which may be coupled to the negative electrode of the filament power source 482. The (one or more) conductive paths 260 may be interposed between the anode 220 and the cathode 240. The (one or more) conductive paths 260 may be arranged in a radial pattern. For example, a space between the anode 220 and the cathode 240 may be sectored into a plurality of regions and the (one or more) conductive paths 260 may be provided in each of the regions. The conductive paths 260 may be arranged in zigzag pattern with arcs centered on the anode 220. For example, the conductive paths 260 may have the same center of curvature, but a length of a radius may be different. In each of the plurality of regions, the conductive paths 260 may link with each other at adjacent ends so as to provide a united route. The conductive paths 260 may be symmetric with respect to the anode 220.
According to an example embodiment, as illustrated in
As the conductive paths 260 may be arranged toward the edge regions (the cathode 240) from the center region (the anode 220), thermions may be discharged more uniformly throughout the filament member 200.
Because the filament member 200 may have a plurality of conductive paths 260, an ion implantation apparatus may continue to operate without interruption even when one of the conductive paths 260 may be shorted due to the sputtering etch effect.
Although the anode 220, the cathode 240, and the at least one conductive path 260 may be made of tungsten, the anode 220 and cathode 240 may be formed of other metals. However, the materials of the anode 220 and cathode 240 should be strong enough to resist the sputtering etch effect because the anode 220 and cathode 240 may be eroded by positive ions.
The conductive paths 260 may be configured with a flat front face 261 opposite to the region through which the processing gas flows into the arc chamber 100. The flat front face 261 may guide the positive ions vertically into the conductive paths 260 when positive ions generated from regions adjacent to the conductive paths 260 collide with the conductive paths 260. The flat front face 261 may reduce an etch rate of the sputtering etch effect. According to an example embodiment, as illustrated in
As illustrated in
An example embodiment of manufacturing a filament member 200 will now be described. A circular main body made of tungsten may be prepared. Outer boundaries 282 (shown in
A plurality of inner boundaries 284 (shown in FIGS. 5 and 9A-9C) may be formed in the shape of arcs centered on an anode 220. One end of an inner boundary 284 may be linked with one of the outer boundaries 282, while another end of an inner boundary 284 may be isolated from the other one of the outer boundaries 282 in the fan-shaped region. The plurality of inner boundaries 284 may be arranged in the same interval, but, the plurality of inner boundaries 284 may be different from each other in each interval for the purpose of selectively emitting thermions in accordance with regional requirements. Processing the filament member 200 may be accomplished by means of a high-temperature die casting, electrical discharge machining, and/or wire cutting.
The (one or more) conductive paths 260 may be formed to have an extended length by the method described above to increase the amount of thermions discharged, thereby enhancing the efficiency of ionizing the source gas.
According to another example embodiment, a cathode 240 may be formed to enclose the conductive paths 260 to sufficiently prevent emission of thermions therefrom. The thermions from the conductive paths 260 may be discharged toward a fourth sidewall 180, without being forwarded directly to first and second sidewalls 120 and 140. Example embodiments may be effective in preventing the first and second sidewalls 120 and 140 of the arc chamber 100 from being damaged due to collision with thermions.
As illustrated in
A method of forming the filament member 200 f illustrated in
According to example embodiments, a filament member may more uniformly emit thermions. The life-span of the filament member may be increased by lowering a sputtering etch effect. In addition, the filament member may continuously operate even when one of the current paths is shorted by a sputtering etch effect. Moreover, example embodiments may prevent electrons, which may be discharged from the filament, from colliding with sidewalls of an arc chamber.
The above-disclosed subject matter may be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the scope of the example embodiments.