Patent Application
20230197422
The disclosure relates generally to processing apparatus for semiconductor devices, and more particularly to a fastening assembly for mounting a beam blocker in an ion processing system.
Plasmas are sometimes used to process semiconductor substrates, such as those used in electronic devices, for applications such as substrate etching, layer deposition, ion implantation, and other processes. Some processing apparatus employ a plasma chamber for generating a plasma to act as an ion source for substrate processing. An ion beam may be extracted through an extraction assembly and directed to a substrate in an adjacent chamber. In some cases, the ion beam may be split around a so-called “beam blocker” disposed adjacent an extraction aperture of the extraction assembly to form a pair of symmetrical, angled ion beamlets directed toward the substrate. The beam blocker may be fastened to an extraction plate on opposing sides of the extraction aperture by a pair of fastening assemblies formed of cooperating mounting pins, spacers, and latches.
A shortcoming associated with fasteners of the type descried above is a tendency to cause misalignment of the beam blocker relative to the extraction aperture, resulting in a lack of symmetry between the beamlets directed toward a target substrate. For example, the entire beam blocker may sag, resulting in a gap above the beam blocker being larger than a gap below the beam blocker. In another example, one side of the beam blocker may sag relative to the opposing side of the beam blocker, resulting in the extraction of “twisted” ion beamlets. Such misalignment may result from variations in the sizes of the components of the fastening assemblies due to manufacturing tolerances, and/or may result from sagging of the beam blocker due to gravity.
With respect to these and other considerations the present disclosure is provided.
This Summary is provided to introduce a selection of concepts in a simplified form. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is this Summary intended as an aid in determining the scope of the claimed subject matter.
An embodiment of a fastening assembly for fastening a beam blocker to an extraction plate of an ion processing system in accordance with the present disclosure may include a mounting pin having a cylindrical shaft portion, a base portion at a first end of the shaft portion, and a head portion at an opposing, second end of the shaft portion, a tubular centering sleeve radially surrounding the shaft portion and axially abutting the base portion, the centering sleeve being adapted to be radially compressed between the shaft portion and the extraction plate and between the shaft portion and the beam blocker, an annular spacer radially surrounding the centering sleeve and the shaft portion of the mounting pin and axially abutting the beam blocker, with the centering sleeve extending partially into, and not entirely through, the spacer, and a latching cap radially surrounding the shaft portion and axially abutting the spacer, with the shaft portion extending through a through hole of the latching cap, the through hole of the latching cap being smaller than the head portion in a direction perpendicular to an axis of mounting pin.
An ion processing system in accordance with the present disclosure may include a plasma chamber, a process chamber adjacent the plasma chamber, and an extraction assembly disposed between the plasma chamber and the process chamber. The extraction assembly may include an extraction plate disposed along a side of the plasma chamber and defining an extraction aperture, and a beam blocker disposed adjacent the extraction aperture and fastened to the extraction plate by a fastening assembly. The fastening assembly may include a mounting pin having a cylindrical shaft portion extending through a mounting aperture in the extraction plate and through a mounting aperture in the beam blocker, a base portion at a first end of the shaft portion, and a head portion at an opposing, second end of the shaft portion, a tubular centering sleeve radially surrounding the shaft portion within the mounting aperture of the extraction plate and within the mounting aperture of the beam blocker and axially abutting the base portion, the centering sleeve held in radial compression between the shaft portion and the extraction plate and between the shaft portion and the beam blocker, an annular spacer radially surrounding the centering sleeve and the shaft portion of the mounting pin and axially abutting the beam blocker, the centering sleeve extending partially into, and not entirely through, the spacer, and a latching cap radially surrounding the shaft portion and axially abutting the spacer, with the shaft portion extending through a through hole of the latching cap, the through hole of the latching cap being smaller than the head portion in a direction perpendicular to an axis of mounting pin.
A method of fastening a beam blocker to an extraction plate of an ion processing system in accordance with the present disclosure may include inserting a mounting pin into a mounting aperture in an extraction plate through a front of the extraction plate, the mounting pin having a cylindrical shaft portion, a base portion at a first end of the shaft portion, and a head portion at an opposing, second end of the shaft portion, inserting a first radial half of a centering sleeve into the mounting aperture of the extraction plate, radially intermediate the shaft portion of the mounting pin and the extraction plate and in axial abutment with the base portion of the mounting pin, inserting a second radial half of the centering sleeve into the mounting aperture of the extraction plate, radially intermediate the shaft portion of the mounting pin and the extraction plate and in axial abutment with the base portion of the mounting pin, the second radial half of the centering sleeve mating with the first radial half of the centering sleeve to define a tubular body held in radial compression between the shaft portion of the mounting pin and the extraction plate, placing the beam blocker over the mounting pin and the centering sleeve, with the shaft portion of the mounting pin and the centering sleeve extending through a mounting aperture of the beam blocker, and with the beam blocker being disposed in flat abutment with a rear of the extraction plate, wherein the tubular body of the centering sleeve is held in radial compression between the shaft portion of the mounting pin and the beam blocker, mating first and second radial halves of a spacer together on the centering sleeve to define an annular body axially abutting the beam blocker, with the centering sleeve extending partially into, a through hole of the spacer, placing an annular latching cap over the head portion of the mounting pin, with the head portion being aligned with, and inserted through, a correspondingly shaped through hole of the latching cap, wherein the latching cap is disposed on the shaft portion of the mounting pin and on the spacer in a radially surrounding relationship therewith, and rotating the latching cap relative to the mounting pin to move the through hole of the latching cap out of alignment with the head portion of the mounting pin, thus preventing the latching cap from being axially slid off the mounting pin.
The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, where some embodiments are shown. The subject matter of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the drawings, like numbers refer to like elements throughout.
As used herein, an element or operation recited in the singular and proceeded with the word “a” or “an” are understood as potentially including plural elements or operations as well. Furthermore, references to “an embodiment” of the present disclosure are not intended to be interpreted as precluding the existence of additional embodiments also incorporating the recited features.
The embodiments described herein provide devices and methods for mounting and centering a beam blocker of an ion processing system in a manner that mitigates misalignment of the beam blocker, such as may otherwise result from tolerance stack up in the components of the beam blocker and/or from sagging of the beam blocker due to gravity. Improving the alignment of the beam blocker may enhance the symmetry of ion beamlets projected around the beam blocker, in-turn enhancing the processing (e.g., etching, implantation, etc.) of a target substrate.
Referring to
The extraction assembly 106 may further include an extraction plate 120, disposed along a side of the plasma chamber 102. The extraction plate 120 may define an extraction aperture 122 elongated along the X-axis of the Cartesian coordinate system shown in
Referring back to
Referring to
As briefly described above, the first and second fastening assemblies 134a, 134b are adapted to fasten the beam blocker 130 to the extraction plate 120 in a manner that ensures or improves vertical centering and alignment of the beam blocker 130 with respect to the extraction aperture 122. The first and second fastening assemblies 134a, 134b may include respective mounting pins 140a, 140b, centering sleeves 142a, 142b, spacers 144a, 144b, O-rings 146a, 146b, and latching caps 148a, 148b. Referring to
The mounting pin 140a may extend through a mounting aperture 156 in the extraction plate 120, with the base portion 150 of the mounting pin 140a disposed within a counterbore 158 of the mounting aperture 156 formed in a front surface (i.e., rightmost surface as oriented in
The shaft portion 152 of the mounting pin 140a may extend through a mounting aperture 160 in the beam blocker 130. The diameter of the mounting aperture 160 may be equal to, or similar to, the diameter of the mounting aperture 156 in the extraction plate 120. In various non-limiting examples, diameter of the mounting aperture 160 may be 12.14 millimeters+/−.08 millimeters. The centering sleeve 142a may be a generally tubular member formed of a resilient material. The centering sleeve 142a may surround the shaft portion 152 of the mounting pin 140a and may extend through the mounting apertures 156, 160 of the extraction plate 120 and the beam blocker 130 with a forwardmost end of the centering sleeve 142a abutting the base portion 150 of the mounting pin 140a. The centering sleeve 142a may have an uncompressed outer diameter slightly larger than the diameters of the mounting apertures 156, 160 of the of the extraction plate 120 and the beam blocker 130. In various non-limiting examples, the uncompressed outer diameter of the centering sleeve 142a may be 12.83 millimeters+/−.05 millimeters larger than the diameters of the mounting apertures 156, 160 of the extraction plate 120 and the beam blocker 130. When the centering sleeve 142a is operatively installed in the first fastening assembly 134a as shown in
In various embodiments, the centering sleeve 142a may be formed of polytetrafluoroethylene (PTFE) or other similarly resilient, plasma resistant material. The present disclosure is not limited in this regard. Referring to
Referring again to
The latching cap 148a of the first fastening assembly 134a may be a generally annular, cap-shaped member disposed on (i.e., radially surrounding) the shaft portion 152 of the mounting pin 140a and the spacer 144a, and axially abutting the rear of the spacer 144a. The latching cap 148a may define a through hole 170 having an oblong shape similar to, though slightly larger than, the shape of the head portion 154 of the mounting pin 140a (best shown in
Referring to
At block 200 of the exemplary method, the mounting pin 140a may be inserted into the mounting aperture 156 through front of the extraction plate 120 and the base portion 150 of the mounting pin 140a may be seated within the counterbore 158 of the mounting aperture 156. Seated thusly, the forward-facing surface of the base portion 150 may be generally coplanar with the front surface of the extraction plate 120.
At block 210 of the exemplary method, the first radial half 142a1 of the centering sleeve 142a may be inserted into mounting aperture 156 through the rear of the extraction plate 120 and may be seated within the mounting aperture 156 radially intermediate the shaft portion 152 of the mounting pin 140a and the extraction plate 120 and in axial abutment with the base portion 150 of the mounting pin 140a. At block 220 of the method, the second radial half 142a1 of the centering sleeve 142a may be inserted into mounting aperture 156 through the rear of the extraction plate 120 and may be seated within the mounting aperture 156 radially intermediate the shaft portion 152 of the mounting pin 140a and the extraction plate 120 and in axial abutment with the base portion 150 of the mounting pin 140a. The first and second radial halves 142a1, 142a2 may be mated together on the shaft portion 152 to define the tubular centering sleeve 142a. Seated within the mounting aperture 156 thusly, the centering sleeve 142a may be held in radial compression between the shaft portion 152 of the mounting pin 140a and the extraction plate 120 (e.g., via interference fit/friction fit).
At block 230 of the exemplary method, the beam blocker 130 may be placed over the mounting pin 140a and the centering sleeve 142a, with the shaft portion 152 of the mounting pin 140a and the centering sleeve 142a extending through the mounting aperture 160 of the beam blocker 130, and with the beam blocker 130 being disposed in flat abutment with the rear of the extraction plate 120. Seated within the mounting aperture 160 thusly, the centering sleeve 142a may be held in radial compression between the shaft portion 152 of the mounting pin 140a and the beam blocker 130 (e.g., via interference fit/friction fit).
At block 240 of the exemplary method, the O-rings 146a may be seated within respective cavities 172 in the first and second radial halves 144a1, 144a2 of the spacer 144a. When the O-rings 146a are in an uncompressed state, they may protrude slightly from the cavities 172. At block 250 of the method, the first and second radial halves 144a1, 144a2 may be mated together on the shaft portion 152 and centering sleeve 142a to define the annular spacer 144a axially abutting a rear of the beam blocker 130, with the centering sleeve 142a extending partially into, and not entirely through, the through hole 164 of the spacer 144a. In various non-limiting embodiments, the spacer 144a may include a radially inwardly extending flange 166 radially overhanging a rear side of the through hole 164. The flange 166 may define a secondary through hole 168 having a smaller diameter than the through hole 164 and may serve to shield the centering sleeve 142a from ionic bombardment during operation of the system 100 to prevent or mitigate etching of the centering sleeve 142a.
At block 260 of the exemplary method, the latching cap 148a may be placed over the head portion 154 of the mounting pin 140a, with the oblong head portion 154 being aligned with, and inserted through, the correspondingly oblong through hole 170 of the latching cap 148a. The latching cap may be disposed on the shaft portion 152 of the mounting pin 140a and on the spacer 144a in a radially surrounding relationship therewith. The latching cap 148a may be pressed into axial abutment with the rear of the spacer 144a, with the O-rings 146a being compressed into their respective cavities 172. While the latching cap 148a is held in this position, with the O-rings 146a held under compression, the latching cap 148a may, at block 270 of the exemplary method, be rotated 90 degrees (or within a range surrounding 90 degrees, e.g., 60 degrees-120 degrees) about its axis, thus rotating the through hole 170 out of alignment with the head portion 154 of the mounting pin 140a. With the latching cap 148a installed thusly, the head portion 154 may prevent the spacer 144a from moving rearwardly, and the spring force of the compressed O-rings 146a may exert axially directed forces on the latching cap 148a and the spacer 144a to hold the head portion 154, the latching cap 148a, the spacer 144a, the beam blocker 130, and the extraction plate 120 in firm axial engagement with one another.
At block 280 of the exemplary method, the actions performed in the above-described blocks 200-270 with respect to the first fastening assembly 134a may be repeated with the second fastening assembly 134b to fasten the opposing longitudinal end of the beam blocker 130 to the extraction plate 120.
In view of the above, the present disclosure provides at least the following advantages. As a first advantage, the fastening assemblies of the present disclosure operate to prevent or mitigate misalignment of a beam blocker relative to an extraction aperture of an ion processing system, thus ensuring or enhancing the symmetry of ion beamlets projected around the beam blocker toward a target substrate. As a second advantage, the fastening assemblies of the present disclosure can be quickly and easily installed. As a third advantage, the fastening assemblies of the present disclosure are self-protective against undesirable ion etching of internal components (i.e., the centering sleeves 142a, 142b).
While certain embodiments of the disclosure have been described herein, the disclosure is not limited thereto, as the disclosure is as broad in scope as the art will allow and the specification may be read likewise. Therefore, the above description is not to be construed as limiting. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.
