TWM544104U - Suppresion electrode of electrostatic lens for use in ion implanter - Google Patents

Abstract

The utility provides a suppression electrode of an electrostatic lens for use in an ion implanter. The electrostatic lens includes a terminal electrode, a ground electrode and first and second suppression electrodes. Each of the electrodes includes an hourglass-shaped opening therein for receiving an ion beam traveling in a z direction therethrough. The hourglass-shaped opening in the terminal electrode has a size that is different from a size of the opening in at least one of the first and second suppression electrodes and the ground electrode. Each electrode also includes at least one curved (convex or concave) face as observed in the y-z plane, where the y-direction is a vertical direction and the z-direction is the direction of travel of the ion beam. The curvatures of the faces of the electrodes can be different between adjacent electrodes so that a distance between adjacent electrodes at upper and lower extremities of the adjacent electrodes is different from a distance between the adjacent electrodes at their centers.

Description

Suppression electrode for electrostatic lens used in ion implanter

The present invention is directed to the field of ion implantation and, in particular, to a quadrupole lens for use in an ion implantation tool.

Ion implantation is a process for doping impurity ions into a substrate such as a semiconductor wafer. In general, the ion beam is directed from the ion source chamber toward the substrate. Different feed gases are supplied to the ion source chamber to obtain plasma for forming an ion beam having specific dopant characteristics. For example, from the feed gas PH _3, BF ₃ or AsH _3, various atomic and molecular ions formed in the ion source, and subsequently subjected to selection and quality of acceleration. The depth at which the generated ions are implanted into the substrate is based on the ion implantation energy and the quality of the ions. One or more types of ionic species can be implanted in the target wafer or substrate at different doses and at different energy levels to achieve the desired device characteristics. The precise doping profile in the substrate is critical to proper device operation.

Ion implanters are widely used in semiconductor fabrication to provide such doping profiles or modify different materials in a substrate. In a typical ion implanter, ions generated from an ion source are directed through a series of beamline elements that can To include one or more analytical magnets and multiple electrodes. The analysis magnet selects the desired ionic species, filters out contaminants and ions with undesired energy, and adjusts the ion beam quality at the target wafer. A suitably shaped electrode (often referred to as a "lens") is used to modify the energy and shape of the ion beam at different points along the travel of the beam. Significant changes in ion energy can occur in such lenses and can have a considerable impact on the shape of the ion beam. The shape of the ion beam can in turn affect the quality of the final doping profile of the target substrate. Conventional systems and methods may not provide the desired degree of control as the ion beam is deflected and/or concentrated by the ion beam directed to the target substrate.

The present invention discloses a suppression electrode for an electrostatic lens used in an ion implanter. The suppression electrode has a first surface and a second surface and a suppression electrode opening for receiving an ion beam traveling therethrough along the z-axis, at least one of the first surface and the second surface being curved in the y-z plane. The suppressing pole opening has a top end, a bottom end, and a center portion, and suppressing a width of the electrode opening at the top end and the bottom end is greater than a width of the suppressing electrode opening at the central portion, and suppressing a width of the electrode opening at the tip end is equal to suppressing the electrode opening at the bottom The width at the end. The first surface of the suppression electrode has a first radius of curvature, and the second surface of the suppression electrode has a second radius of curvature, and wherein the first radius of curvature and the second radius of curvature are measured from points along the negative "z" axis, Wherein the negative z-axis is measured from the center of the suppression electrode in the opposite direction of travel of the ion beam, and wherein the first radius of curvature is less than the second radius of curvature.

In an embodiment of the novel creation, the first surface of the suppression electrode viewed in the y-z plane is concave.

In an embodiment of the novel creation, the second surface of the suppression electrode viewed in the y-z plane is convex.

In an embodiment of the novel creation, the first radius of curvature and the second radius of curvature are in the range of 250 mm to 310 mm.

Based on the above, the electrostatic lens can obtain a variety of different beam shapes by adjusting the suppression electrode.

The above described features and advantages of the present invention will become more apparent and understood from the following description.

95‧‧‧Ion Beam

100‧‧‧Ion implanter

102‧‧‧Ion source

106‧‧‧Analyzer magnet

108‧‧‧Quality analysis gap

109‧‧‧Deceleration lens

110‧‧‧Scanner

112‧‧‧ collimator

114‧‧‧Background platform

116‧‧‧Substrate

118‧‧‧Accelerator/Reducer

120‧‧‧Drive system

200‧‧‧Electrostatic lens

202‧‧‧ terminal electrode

204‧‧‧First suppression electrode

206‧‧‧Second suppression electrode

208‧‧‧Ground electrode

210‧‧‧First space

212‧‧‧Second space

214‧‧‧ Third Space

202a, 204a, 206a, 208a‧‧‧ top part

202b, 204b, 206b, 208b‧‧‧ bottom part

202c, 204c, 206c, 208c‧‧‧ main part

202d, 204d, 206d, 208d‧‧‧ openings

202e, 204e, 206e, 208e‧‧‧ first surface

202f, 204f, 206f, 208f‧‧‧ second surface

The top of the opening of 216, 216a, 216b, 216c, 216d‧‧

Central part of the opening of 218, 218a, 218b, 218c, 218d‧‧

220‧‧‧Quality analysis structure

220a, 220b, 220c, 220d‧‧‧ bottom end of the opening

221‧‧‧ bottom

223‧‧‧Scanner assembly

W‧‧‧Width

H‧‧‧ Height

OH‧‧‧ opening height

OHb‧‧‧ opening height

OHa‧‧‧ opening height

OHc‧‧ ‧ opening height

OHd‧‧‧ opening height

OW1, OW1b, OW2b, OW3b‧‧‧ opening width

OW1a, OW2a, OW3a‧‧‧ opening width

OW1c, OW2c, OW3c‧‧‧ opening width

OW1d, OW2d, OW3d‧‧‧ opening width

LR1b‧‧‧ radius of curvature

LR1a‧‧‧ radius of curvature

LR2a‧‧‧ radius of curvature

LR2b‧‧‧ radius of curvature

LR3a‧‧‧ radius of curvature

LR3b‧‧‧ radius of curvature

LR4a‧‧‧ radius of curvature

LH1‧‧‧Lens height

LW1‧‧ lens width

LH2‧‧‧Lens height

LW2‧‧‧ lens width

LH3‧‧‧Lens height

LW3‧‧‧ lens width

LH4‧‧‧Lens height

LW4‧‧‧ lens width

UE‧‧‧Upper

LE‧‧‧Bottom

D1‧‧‧ distance

D2‧‧‧ distance

1 is a schematic diagram illustrating an ion implantation system in accordance with the present invention.

2 is a side view of an exemplary electrostatic lens in accordance with the present invention.

3 is an end view of the electrostatic lens of FIG. 2.

4A and 4B are side views of the electrostatic lens of Fig. 2 illustrating a single mode of operation.

5 through 7 are correspondingly isometric, front and side views of an exemplary end electrode of the electrostatic lens of Fig. 2.

8 through 10 are correspondingly isometric, front and side views of an exemplary first suppression electrode of the electrostatic lens of Fig. 2.

11 to 13 are correspondingly exemplary second suppression powers of the electrostatic lens of FIG. 2 Extreme isometric view, front view and side view.

14 through 16 are correspondingly isometric, front and side views of an exemplary ground electrode of the electrostatic lens of Fig. 2.

17 is a schematic illustration of an exemplary non-concentric surface configuration between adjacent electrodes of the electrostatic lens of FIG. 2.

18 through 24 are exemplary diagrams of electric field lines associated with the electrostatic lens of Fig. 2.

1 depicts a top plan view of a frame form of a beamline ion implanter shown as an ion implanter 100 in accordance with various embodiments of the present invention. The ion implanter 100 includes an ion source 102 that is configured to generate an ion beam 95. The ion beam 95 can be provided as a point beam or a ribbon beam having a beam width (along the X direction of the Cartesian coordinates shown) that is greater than the beam height (along the Y direction). In the rules used herein, the Z direction refers to the direction parallel to the axis of the central ray trajectory of the ion beam 95. Thus, the absolute direction in the Z direction and the X direction (perpendicular to the Z direction) can be varied at different points within the ion implanter 100, as shown.

The ion source 102 can include an ion chamber in which the feed gas supplied to the ion chamber is ionized. The gas may be or may include or include the following: hydrogen, helium, other rare gases, oxygen, nitrogen, arsenic, boron, phosphorus, aluminum, indium, antimony, carborane, alkanes, another macromolecular compound Or other p-type or n-type dopants. The generated ions can be extracted from the ion chamber through a series of extraction electrodes (not shown) to form an ion beam 95. Placed on the substrate platform 114 in an impact The ion beam 95 can travel through the analyzer magnet 106, the quality resolution slit 108, the deceleration lens 109, and through the collimator 112 before the substrate 116. In some embodiments the substrate platform 114 can be configured to scan the substrate 116 at least along the Y direction.

In the example shown in FIG. 1, ion beam 95 can be provided as a spot beam scanned by scanner 110 along the X direction to provide a scanned ion beam having a width similar to the width W of substrate 116. 95. In other embodiments, the ion beam 95 can be provided as a ribbon beam. In the example of FIG. 1, other beamline elements useful for operation of ion implanter 100 that are apparent to those of ordinary skill in the art are omitted for clarity.

The ion implanter 100 further includes an accelerator/reducer 118. As shown in FIG. 1, the accelerator/reducer 118 can be disposed at point A between the ion source 102 and the analyzer magnet 106. In other embodiments, the accelerator/reducer 118 can be disposed at other locations within the ion implanter 100, such as point B or point C. The accelerator/reducer 118 can be coupled to a drive system 120 that is operable to adjust the position of one of the electrodes within the accelerator/reducer 118 relative to the other electrodes. This in particular allows the beam current in the ion beam 95 to be adjusted at a given ion energy of the ion beam 95.

In various embodiments, the ion implanter 100 can be configured to deliver an ion beam 95 for "intermediate" energy ion implantation, or 60 kV to an implant energy range of 60 keV to 300 keV for a single charged ion. 300kV voltage range. As discussed below, the lens of the accelerator/reducer 118 is electrically insulated from the end suppression electrode and independently driven, thus allowing for increased beam power of the ion implanter 100. Flow operation range.

2 is a side view of an exemplary electrostatic lens 200 having a terminal electrode 202, a first suppression electrode 204 and a second suppression electrode 206, and a ground electrode 208, which may be used as the lens 109 shown in FIG. . Adjacent electrodes are spaced along the z-axis (ie, along the direction of travel of the ion beam 95). Therefore, the first space 210 may be formed between the terminal electrode 202 and the first suppression electrode 204, the second space 212 may be formed between the first suppression electrode 204 and the second suppression electrode 206, and the third space 214 may be formed on The second suppression electrode 206 is between the ground electrode 208. As will be described, the disclosed electrostatic lens 200 is a quadrupole deceleration lens and is designed to decelerate the ion beam 95 with a high and relatively thin slightly divergent input ion beam 95 and produce a more concentrated parallel or converging The output ion beam 95.

Each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 may include a top portion 202a, 204a, 206a, 208a, a bottom portion 202b, 204b, 206b, 208b, and a body portion 202c, 204c , 206c, 208c. Each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 further includes openings 202d, 204d, 206d, 208d (FIG. 3) that define body portions 202c, 204c of each electrode, The orifices in 206c, 208c pass through the electrostatic lens 200 in the z-direction through the orifice having a width "W" in the x-direction and a height "H" in the y-direction. The voltage applied to each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 can be used to shape the beam as the ion beam 95 passes through the electrostatic lens 200. As will be described in more detail later, the terminal electrode 202, the first suppression electrode 204, the first The shape of the second suppression electrode 206 and the ground electrode 208 can also be used to shape the beam as the ion beam 95 passes through the electrostatic lens 200.

The body portions 202c, 204c, 206c, 208c of each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 may include opposing first surfaces 202e, 204e, 206e, 208e, and second Surfaces 202f, 204f, 206f, 208f, wherein the first surface generally faces the oncoming ion beam 95. Some of the first surfaces 202e, 204e, 206e, 208e and the second surfaces 202f, 204f, 206f, 208f of each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 may be Flat, and the first surface 202e, 204e, 206e, 208e and the second surface 202f, 204f, 206f, 208f of each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 are Some of them can be curved. For example, in some embodiments, the first surface 202e, 204e, 206e, 208e of each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 when viewed from the side And the second surface 202f, 204f, 206f, 208f may be convex, concave or flat.

In the illustrated embodiment, as viewed in the yz plane (where the "y" axis is vertical and the "z" axis is along the direction of travel of the ion beam 95), the first surface 202e of the tip electrode 202 and the first The first surface 204e of the suppression electrode 204 is convex, as viewed in the yz plane, the first surface 206e of the second suppression electrode 206 and the first surface 208e of the ground electrode 208 are concave, as in the yz plane Observed, the second surface 202f of the terminal electrode 202 and the second surface 204f of the first suppression electrode 204 are concave, as viewed in the yz plane, the second surface of the second suppression electrode 206 206f is convex and the second surface 208f of the ground electrode 208 is flat. This causes the terminal electrode 202 to be "bulged" in the negative "z" direction, the first suppression electrode 204 is "bumped" in the negative and positive "z" directions, and the second suppression electrode 206 is in the positive "z" The direction is "bulging". Since the first surface 208e of the ground electrode 208 is concave and the second surface 208f is substantially flat, the ground electrode 208 appears concave in the positive "z" direction. The particular illustrated arrangement of the surface shape will be understood to be illustrative and not limiting, and other combinations of curvatures may be used.

As can be seen, adjacent surfaces of adjacent electrodes are substantially complementary (ie, the concave surfaces are positioned adjacent to the opposing convex surfaces). This causes the first space 210, the second space 212, and the third space 214 in the middle as viewed from the side of the electrostatic lens 200 to be curved (i.e., as previously defined, they are curved in the y-z plane).

3 shows an end view of electrostatic lens 200 showing end electrode 202, first suppression electrode 204, second suppression electrode 206, and ground electrode 208 of exemplary ion beam 95 having a height "H" and a width "W" Openings 202d, 204d, 206d, 208d. As can be seen, the opening 202d of the terminal electrode 202 has an hourglass shape. Thus, opening 202d can have an opening height "OH" measured along the y-axis, a first opening width "OW1" as measured along the x-axis at the top end 216 of the opening, along the x-axis at the central portion 218 of the opening The measured second opening width "OW2" and the third opening width "OW3" measured along the x-axis at the bottom end 221 of the opening. The first opening width "OW1" and the third opening width "OW3" may be the same, and the second opening width "OW2" may be smaller than the first opening width "OW1" and the third opening width "OW3". This configuration provides the desired hourglass shape shown in FIG. As will be described in more detail later, the openings 204d, 206d, 208d of the other electrodes may have a similar hourglass configuration with an opening height and an opening width as described with respect to the opening 202d of the terminal electrode. In some embodiments, the openings 202d, 204d, 206d, 208d all have the same shape and size, while in other embodiments some of the openings are different in shape and/or size from those of the other openings.

The electrostatic lens 200 can be a deceleration lens configured to decelerate the ion beam 95 such that the beam hits the target working part at the desired implantation energy. A voltage potential can be selectively applied to each of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 to manipulate the ions of the ion beam 95 as the ion beam 95 travels through the electrostatic lens 200. energy. Referring to Figures 4A and 4B, two modes of operation of the electrostatic lens 200 are illustrated. Electrostatic lens 200 is shown in the context of quality resolution structure 222 in these figures, and an exemplary scanner assembly 223, which may include electrodes, is biased to scan the beam in a desired manner.

The operation of the single mode is illustrated in Figure 4A. As will be appreciated, single mode can be used for higher energy beams. In this mode, the quality resolution structure 220, the terminal electrode 202, the second suppression electrode 206, and the ground electrode 208 are maintained at a ground potential while the first suppression electrode 204 is maintained at a negative potential. Such an arrangement can provide for agglomeration of the higher energy ion beam 95. The "deceleration" mode of operation with two-step deceleration is illustrated in Figure 4B. The quality resolution structure 220 and the terminal electrode 202 will remain at the same potential "VT". The first suppression electrode 204 will remain at the lower potential "VS1" to suppress the flow of electrons, the ground electrode 208 will remain at the ground potential, and the second suppression electrode 206 will remain at the intermediate potential "VS2". It will be understood that these models are exemplary and not limiting. of. In practice the electrodes can be maintained at any of a variety of potentials to produce an ion beam 95 having the desired set of characteristics.

Referring to Figures 5 through 7, the terminal electrode 202 will be described in more detail. The terminal electrode 202 may have a lens height "LH1" as measured along the y-axis, and a lens width "LW1" as measured along the x-axis. As previously described, the tip electrode 202 can have a top portion 202a, a bottom portion 202b, a body portion 202c, and an opening 202d. The opening 202d may have an hourglass shape having an opening height "OHa" measured along the y-axis, a first opening width "OW1a" as measured along the x-axis at the top end 216a of the opening, and a center along the x-axis at the opening The second opening width "OW2a" measured at portion 218a, and the third opening width "OW3a" measured at the bottom end 220a of the opening along the x-axis. The first opening width "OW1a" and the third opening width "OW3a" may be the same, and the second opening width "OW2a" may be smaller than the first opening width "OW1a" and the third opening width "OW3a".

As previously described, the first surface 202e and the second surface 202f of the terminal electrode 202 can be curved. Thus, the first surface 202e can have a first radius of curvature "LR1a" and the second surface 202f can have a second radius of curvature "LR1b". Both radii of curvature may be measured from points along the positive "z" axis (ie, downstream of electrostatic lens 200 in the direction in which ion beam 95 travels). In the illustrated embodiment, the first radius of curvature "LR1a" is greater than the second radius of curvature "LR1b".

The first suppression electrode 204 will be described in more detail with reference to FIGS. 8 to 10. The first suppression electrode 204 may have a lens height "LH2" as measured along the y-axis, and a lens width "LW2" as measured along the x-axis. First suppression as previously described The electrode 204 can have a top portion 204a, a bottom portion 204b, a body portion 204c, and an opening 204d. The opening 204d may have an hourglass shape having an opening height "OHb" measured along the y-axis, a first opening width "OW1b" as measured along the x-axis at the top end 216b of the opening, and a center along the x-axis at the opening The second opening width "OW2b" measured at portion 218b, and the third opening width "OW3b" measured at the bottom end 220b of the opening along the x-axis. The first opening width "OW1b" and the third opening width "OW3b" may be the same, and the second opening width "OW2b" may be smaller than the first opening width "OW1b" and the third opening width "OW3b".

As can be seen, the size of the opening 204d of the first suppression electrode 204 can be different than the size of the opening 202d of the terminal electrode 202. For example, in the illustrated embodiment, the opening height "OHb" of the first suppression electrode 204 is smaller than the opening height "OHa" of the terminal electrode 202, and the opening widths "OW1b", "OW2b" of the first suppression electrode 204. "OW3b" can be correspondingly larger than the opening widths "OW1a", "OW2a", and "OW3a" of the terminal electrode 202.

The first surface 204e and the second surface 204f of the first suppression electrode 204 may be curved. Thus, the first surface 204e can have a first radius of curvature "LR2a" and the second surface 204f can have a second radius of curvature "LR2b". The first radius of curvature "LR2a" may be measured from a point along the positive "z" axis (ie, downstream of the electrostatic lens 200 in the direction in which the ion beam 95 travels), while the second radius of curvature "LR2b" may follow from a negative The point measurement of the "z" axis (i.e., upstream of the electrostatic lens 200 in the opposite direction of travel of the ion beam 95). In the illustrated embodiment, the first radius of curvature "LR2a" is the same as the second radius of curvature "LR2b".

Referring to Figures 11 through 13, the second suppression electrode 206 will be described in more detail. The second suppression electrode 206 may have a lens height "LH3" as measured along the y-axis, and a lens width "LW3" as measured along the x-axis. As previously described, the second suppression electrode 206 can have a top portion 206a, a bottom portion 206b, a body portion 206c, and an opening 206d. The opening 206d may have an hourglass shape having an opening height "OHc" measured along the y-axis, a first opening width "OW1c" as measured along the x-axis at the top end 216c of the opening, and a center along the x-axis at the opening The second opening width "OW2c" measured at portion 218c, and the third opening width "OW3c" measured at the bottom end 220c of the opening along the x-axis. The first opening width "OW1c" and the third opening width "OW3c" may be the same, and the second opening width "OW2c" may be smaller than the first opening width "OW1c" and the third opening width "OW3c".

As can be seen, the size of the opening 206d of the second suppression electrode 206 can be different than the size of the opening 204d of the first suppression electrode 204. For example, in the illustrated embodiment, the opening height "OHb" of the first suppression electrode 204 is smaller than the opening height "OHc" of the second suppression electrode 206, and the opening width "OW1b" of the first suppression electrode 204, " OW2b" and "OW3b" may be correspondingly larger than the opening widths "OW1c", "OW2c", and "OW3c" of the second suppression electrode 206.

As previously described, the first surface 206e and the second surface 206f of the second suppression electrode 206 may be curved. Thus, the first surface 206e can have a first radius of curvature "LR3a" and the second surface 206f can have a second radius of curvature "LR3b". Both radii of curvature may be measured from points along the negative "z" axis (ie, upstream of electrostatic lens 200 in the opposite direction of travel of ion beam 95). In the illustrated embodiment, The first radius of curvature "LR3a" is smaller than the second radius of curvature "LR3b".

Referring to Figures 14 through 16, the ground electrode 208 will be described in more detail. The ground electrode 208 may have a lens height "LH4" as measured along the y-axis, and a lens width "LW4" as measured along the x-axis. As previously described, the ground electrode 208 can have a top portion 208a, a bottom portion 208b, a body portion 208c, and an opening 208d. The opening 208d may have an hourglass shape having an opening height "OHd" measured along the y-axis, a first opening width "OW1d" as measured along the x-axis at the top end 216d of the opening, along the x-axis at the center of the opening The second opening width "OW2d" measured at portion 218d, and the third opening width "OW3d" measured at the bottom end 220d of the opening along the x-axis. The first opening width "OW1d" and the third opening width "OW3d" may be the same, and the second opening width "OW2d" may be smaller than the first opening width "OW1d" and the third opening width "OW3d".

As can be seen, the size of the opening 208d of the ground electrode 208 can be different than the size of the opening 206d of the second suppression electrode 206. For example, in the illustrated embodiment, the opening height "OHd" of the ground electrode 208 is smaller than the opening height "OHc" of the second suppression electrode 206, and the opening width "OW1d", "OW2d", "" of the ground electrode 208 OW3d" may be correspondingly larger than the opening widths "OW1c", "OW2c", and "OW3c" of the second suppression electrode 206.

As previously described, the first surface 208e of the ground electrode 208 can be curved. Thus, the first surface 208e can have a first radius of curvature "LR4a" as measured from a point along the negative "z" axis (ie, upstream of the electrostatic lens 200 in the opposite direction traveled by the ion beam 95). The second surface 208f can be flat (ie, oriented toward vertical In the direction of travel of the ion beam 95 along the "z" axis).

While adjacent surfaces of adjacent electrodes have been described as being substantially complementary (ie, the concave surface is positioned adjacent to the convex surface), the radius of curvature of the adjacent surface may have a non-concentric curvature. Thus, for example, the radius of curvature LR1b of the second surface 202f of the terminal electrode 202 can be less than the radius of curvature LR2a of the first surface 202e of the first suppression electrode 204. Therefore, the distance between the second surface 202f of the terminal electrode 202 and the first surface 202e of the first suppression electrode 204 may be different.

Figure 17 is an exemplary schematic diagram of this non-concentric curvature arrangement. As can be seen, in the case where the radii of curvature of the surfaces of the adjacent electrodes (in this example, the terminal electrode 202 and the first suppression electrode 204) are different, the distance "D1" between the terminal electrode 202 and the first suppression electrode 204 is at the electrode. The center "C" is different from the distance "D2" between the upper electrode 202 and the first suppression electrode 204 at the upper end "UE" and the lower end "LE" of the electrode. In the illustrated embodiment, the respective radii of curvature of the terminal electrode 202 and the first suppression electrode 204 are such that the distance D1 is greater than the distance D2. This means that the gathering is stronger at the top and bottom of the ion beam 95 than at the center of the axis of the ion beam 95. In some embodiments, the terminal electrode 202 and the first suppression electrode electrode 204 can each be maintained at a unique potential, and thus the voltage difference between adjacent electrodes will be constant. Since the electric field is a function of distance, changing the distance between adjacent electrodes allows the electric field to change as needed. It will be appreciated that variations in the electric field can be used to maintain the shape of the ion beam 95 as desired.

In a non-limiting exemplary embodiment, the radius of curvature of the terminal electrode 202 and the first suppression electrode 204 may be several hundred millimeters (mm) (eg, 250 to 310 mm). Within the scope of the electrode, the electrode height may be approximately 100 mm and the electrode width may be from 20 mm to 50 mm. It will be appreciated that these dimensions can be driven by the size of the ion beam 95 and the desired degree of aggregation. Thus, these dimensions are not limiting and the electrodes may be adapted to produce an ion beam 95 having a desired size and concentration.

Although FIG. 17 only shows the difference in radius of curvature between the end electrodes 202 and the adjacent surfaces of the first suppression electrode 204, it will be appreciated that a similar configuration may be provided between any adjacent surfaces of any of the electrodes of the electrostatic lens 200. Additionally, while FIG. 17 illustrates a configuration in which the distance D1 is greater than the distance D2, the distance D2 may also be greater than the distance D1 in the contemplated embodiment. Additionally, it will be appreciated that the electrostatic lens 200 can include a variety of combined configurations, such as with respect to one depicted in FIG. In some embodiments, all of the electrodes of electrostatic lens 200 can incorporate such non-concentric radius of curvature between adjacent electrodes. In other embodiments, less than all of the electrodes of electrostatic lens 200 can incorporate such non-concentric radius of curvature between adjacent electrodes.

As will be appreciated, the disclosed hourglass aperture shape provides a desired electric field shape that more closely matches the desired beam shape than can be achieved with a circular or rectangular aperture. For example, a substantially rectangular aperture will cause the top and bottom of the equipotential to collapse into a circular shape and would be expected to induce a deviation in the ion beam. FIG. 18 shows an exemplary diagram of electric field lines surrounding the hourglass-shaped openings 202d to 208d in the electrostatic lens 200. As can be seen, the hourglass shape can counteract the "elliptical" of the equipotential, allowing for better decoupling of the vertical and horizontal electric fields. The field lines are relatively straight along the sides of the opening 202d, and generally a better shape matching will be placed through the high and thin ion beam 95 of the electrostatic lens 200. Therefore, less deviation will be formed in the ion beam 95.

As mentioned previously, the size of the respective openings 202d to 208d of the terminal electrode 202, the first suppression electrode 204, the second suppression electrode 206, and the ground electrode 208 may vary in height and width. The position and amount of level and vertical accumulation can be adjusted by varying the width and height of the opening, and also by, for example, the voltage across the second suppression electrode 206. In the graph shown in Figure 19, the ion beam 95 can be decelerated from 20 keV to 2 keV. The power supply associated with the first suppression electrode 204 has 22 kV above and the power supply associated with the second suppression electrode 206 has only 3 kV above. As can be seen, most of the equipotential is very tightly packed between the first suppression electrode 204 and the second suppression electrode 206. In this description, the equipotentials are spaced 500V apart. This causes a considerable level of focus in the opening 206d of the second suppression electrode 206, and the concentrated beam exits the electrostatic lens 200, as seen in Figure 20, which is the calculated through the electrostatic lens 200 using the arrangement of Figure 19. The curve of the beam orbit.

In Figure 21, ion beam 95 is decelerated from 20 keV to 2 keV. The power supply associated with the first suppression electrode 204 has 22 kV above and the power supply associated with the second suppression electrode 206 has 10 kV thereon. This causes the equipotential to be fairly evenly spaced between the first suppression electrode 204 and the second suppression electrode 206 and between the second suppression electrode 206 and the ground electrode 208. In this description, the equipotentials are spaced 500V apart. A further result is less level of accumulation in the opening 206d of the second suppression electrode 206. It can be seen that the ion beam 95 appears largely parallel from the electrostatic lens 200, as seen in Figure 22, which is a curve of the calculated beam trajectory through the electrostatic lens 200 using the arrangement of Figure 21 Figure.

Figure 23 is a side view of the graph of Figure 19. As mentioned, in this situation The ion beam 95 is decelerated from 20 keV to 2 keV. The power supply associated with the first suppression electrode 204 has 22 kV above and the power supply associated with the second suppression electrode 206 has only 3 kV above. As shown, most of the equipotential is very tightly packed between the first suppression electrode 204 and the second suppression electrode 206, which causes very little vertical concentration in the opening 206d of the second suppression electrode 206. Again, in this graph, the equipotentials are spaced 500V apart.

Figure 24 is a side view of the graph of Figure 21 . As mentioned, in this case the ion beam 95 is decelerated from 20 keV to 2 keV. The power supply associated with the first suppression electrode 204 has 22 kV above and the power supply associated with the second suppression electrode 206 has 10 kV thereon. As shown, the equipotential is relatively evenly spaced between the first suppression electrode 204 and the second suppression electrode 206 and between the second suppression electrode 206 and the ground electrode 208, which causes the opening 206d of the second suppression electrode 206. Less level of aggregation, but a lot of vertical accumulation. Again, in this graph, the equipotentials are spaced 500V apart.

As will be appreciated, the graphs shown in Figures 18-24 are merely exemplary and apply to one embodiment of electrode shape, opening size, and applied potential. Using the disclosed electrostatic lens 200, a variety of different beam shapes can be obtained by adjusting the individual features described herein (including where the aggregation occurs and how much aggregation occurs).

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the novel creation, and any person skilled in the art can make some changes without departing from the spirit and scope of the novel creation. Retouching, so this new The scope of protection for type creation is subject to the definition of the scope of the patent application attached.

200‧‧‧Electrostatic lens

202‧‧‧ terminal electrode

204‧‧‧First suppression electrode

206‧‧‧Second suppression electrode

208‧‧‧Ground electrode

210‧‧‧First space

212‧‧‧Second space

214‧‧‧ Third Space

202a, 204a, 206a, 208a‧‧‧ top part

202b, 204b, 206b, 208b‧‧‧ bottom part

202c, 204c, 206c, 208c‧‧‧ main part

202e, 204e, 206e, 208e‧‧‧ first surface

202f, 204f, 206f, 208f‧‧‧ second surface

Claims (4)

A suppression electrode for an electrostatic lens in an ion implanter, comprising: a suppression electrode having a first surface and a second surface on opposite sides of a body of the suppression electrode, wherein the suppression electrode comprises a suppression electrode opening For receiving an ion beam traveling therethrough along the z-axis, at least one of the first surface and the second surface being curved in a yz plane; wherein the suppression electrode opening has a top end, a bottom end, and a central portion, and a width of the suppression electrode opening at the top end and the bottom end is greater than a width of the suppression electrode opening at the central portion, and the suppression electrode opening is at the top end a width equal to the width of the suppression electrode opening at the bottom end, wherein the first surface of the suppression electrode has a first radius of curvature and the second surface of the suppression electrode has a second curvature a radius, and wherein the first radius of curvature and the second radius of curvature are measured from a point along a negative "z" axis, wherein the negative "z" axis is from the suppression electrode Measured at the center in the opposite direction of travel of the ion beam, and wherein the first radius of curvature smaller than the second radius of curvature. The suppression electrode of claim 1, wherein the first surface of the suppression electrode observed in the y-z plane is concave. The suppression electrode of claim 2, wherein the second surface of the suppression electrode observed in the y-z plane is convex. The suppression electrode of claim 3, wherein the first radius of curvature and the second radius of curvature are in the range of 250 mm to 310 mm.