WO2012155395A1

WO2012155395A1 - Hot cathode ion source system for generating a ribbon ion beam

Info

Publication number: WO2012155395A1
Application number: PCT/CN2011/078074
Authority: WO
Inventors: 陈炯; 洪俊华; 钱锋
Original assignee: 上海凯世通半导体有限公司
Priority date: 2011-05-17
Filing date: 2011-08-05
Publication date: 2012-11-22
Also published as: CN103477414A; CN102789945A

Abstract

A hot cathode ion source system for generating a ribbon ion beam is provided. The hot cathode ion source system comprises a discharging chamber, a cathode unit composed of a hot cathode and a counter-cathode, and an extracting system. The extracting system has an extracting region composed of extracting slots, which are more than two. The extracting slots parallel to each other in the extracting region. The hot cathode ion source system can remarkably improve the ion beam intensity and distributing uniformity of the extracted ion beam, but also can ensure the optical property of the extracted ion beam.

Description

Hot cathode ion source system for generating band turbulence

Technical field

The present invention relates to a hot cathode ion source system, and more particularly to a hot cathode ion source system for generating a ribbon beam. Background technique

Ion implantation methods are used to introduce atoms or molecules, commonly referred to as impurities, into a target substrate, thereby altering the physical and chemical properties of the substrate material. In many manufacturing fields, particularly in the manufacture of semiconductor products and solar cell products, it is often desirable to utilize a ribbon ion beam for ion implantation of a silicon wafer.

An ion source system for performing ion implantation is provided with an ion source system for generating and extracting an ion beam. There are many different types of ion source systems available today, such as the one shown in Figures 1 and 2, which is a typical hot cathode ion source system. As shown in FIG. 1, the hot cathode ion source system includes a discharge chamber 1 and a cathode unit composed of a hot cathode 2 and a pair of cathodes 3. The discharge chamber 1 is for a gas discharge and generates a plasma 6 state. a vacuum chamber of a desired ion for generating electrons required for gas discharge, wherein the filament 4 therein is used to generate electrons that emit and bombard the hot cathode 2, and the pair of cathodes 3 are used for reflection The electrons emitted by the hot cathode 2. The hot cathode ion source system further includes an extraction system having a lead-out system that draws ions in the discharge chamber 1 at the lead-out area by an electric field to obtain an ion beam beam. As shown in FIG. 2, in the case where it is required to obtain a strip beam, it is common practice to provide a lead slit 5 in the lead-out area from which the ion beam is taken out, wherein the lead slit 5 is narrowed. The shape of the beam is constrained by the long shape of the cross section of the ion beam, and the region where the exit slit 5 is located (shown by the dashed box in Fig. 2) is the lead-out area.

The following drawbacks exist in the hot cathode ion source system as shown in Figures 1 and 2:

1. The beam intensity of the extracted ion beam is not large enough to meet the high beam intensity ion implantation. Demand.

First, in the prior art, only a single lead-out slit is used to extract the ion beam, so the effective area for actually extracting the ion beam is small, and in order to increase the effective area, it is common practice to increase the slit width of the lead-out slit. However, this in turn adversely affects the optical properties of the entire ion source system, especially the extraction system.

Secondly, the hot cathode 2 needs to be heated to a certain extent to emit electrons, so that the size of the hot cathode 2 cannot be designed too large, and on the other hand, only the hot cathode 2 is received in the discharge chamber 1 The plasma concentration in the region where the cathode 3 acts will be higher, and the plasma concentration in the edge region will be relatively lower, which will result only from the central portion of the discharge chamber 1 (corresponding to the receiving The region where the hot cathode 2 and the pair of cathodes 3 act) extracts an ion beam having a relatively high beam intensity, and the intensity of the beam extracted from the edge portion is low.

In addition, due to the design limitations of existing ion implanters, only one ion source system can be used in an ion implanter instead of multiple. Therefore, it is currently impossible to increase the number of ion source systems by simply increasing the number of ion source systems. Flow intensity.

2. The uniformity of the beam intensity distribution of the extracted ion beam is not good. In addition to the low beam intensity at the edge portion due to the limited area of action of the hot cathode 2 and the pair of cathodes 3, the space charge effect also produces uniformity in the cross-sectional longitudinal direction of the ribbon beam. Negative Effects. Summary of the invention

The technical problem to be solved by the present invention is to overcome the insufficient beam intensity of the ion beam extracted by the hot cathode ion source system for generating a strip beam in the prior art, and the uniformity of the beam intensity distribution is not A preferred drawback is to provide a hot cathode ion source system for generating a ribbon beam that can significantly increase the beam intensity of the extracted ion beam and the uniformity of the beam intensity distribution.

The present invention solves the above technical problems by the following technical solutions: A hot cathode ion source system for generating a ribbon beam current system, the hot cathode ion source system comprising a discharge chamber, a hot cathode and a pair of cathodes a cathode unit and an extraction system, the extraction system having a lead-out slit The lead-out area is characterized in that the number of the lead-out slits is two or more, and the lead-out slits are parallel to each other in the lead-out area.

Preferably, the number of the lead seams is two or three.

Preferably, the number of the lead-out slits is four or more, and a gap between the lead-out slits at a central portion of the lead-out area is larger than a gap between the lead-out slits at an edge portion of the lead-out area; and/or The number of the lead-out slits is three or more, and the slit width of the lead-out slit at the central portion of the lead-out area is smaller than the slit width of the lead-out slit at the edge portion of the lead-out area.

Preferably, a plurality of lead-out holes are provided in the gap between the lead-out slits.

Preferably, the shape of the lead-out hole is a circle, a regular polygon, an ellipse or a rectangle.

Preferably, the size of the lead-out hole at the central portion of the lead-out area is smaller than the size of the lead-out hole at the edge portion of the lead-out area; and/or the distribution density of the lead-out hole at the central portion of the lead-out area It is smaller than the distribution density of the extraction holes located at the edge portion of the lead-out area.

Preferably, the number of cathode units is one.

Preferably, the number of the cathode units is two or more.

Preferably, the number of cathode units is two.

Preferably, the hot cathodes of the two cathode units are located on the same side of the discharge chamber.

Preferably, the hot cathodes of the two cathode units are respectively located on opposite sides of the discharge chamber.

The positive effects of the present invention are:

1. The present invention significantly increases the effective area actually used to extract the beam by designing more lead-out slits in the lead-out area, and the strip shape is drawn in the case where the plasma concentration in the discharge chamber remains unchanged. The beam intensity of the beam will increase significantly.

2. The present invention also preferably provides a lead-out hole at a gap between the lead-out slits. Since the beam intensity between the larger beamlets drawn from each of the extraction slits is clearly smaller than the beam intensity inside each of the larger beamlets, if more is used at the gap between the exit slits The outlet holes simultaneously lead to a plurality of smaller beamlets, which are able to compensate for the weaker regions of the original beam intensity, thereby causing the resulting banded beam to be Whole beam cross section Both have extremely high beam intensity uniformity.

3. The present invention also preferably increases the number of cathode cells designed to assist in generating more of the desired ions in the discharge cells, thereby increasing the concentration of plasma therein. This clearly ensures that the beam intensity of the extracted ion beam is significantly improved in the case where the extraction capability of the extraction system is constant or higher. In addition, the increase in the number of cathode cells will also help to expand the lateral region of the discharge cell that can actually extract the ion beam, thereby substantially improving the uniformity between the ion extraction amounts of the different extraction slits, thereby obtaining the beam intensity distribution. A more uniform ion beam.

4. The improved uniformity of the beam intensity distribution of the extracted ion beam also means that the optical properties of the entire ion source system, especially the extraction system, are independently optimized, which ensures the optical quality of the obtained ion beam. DRAWINGS

1 is a schematic view of a discharge chamber and a cathode unit of an existing ion source system for generating a ribbon beam, and is also a discharge chamber and a cathode unit of an ion source system for generating a ribbon beam of the present invention. A schematic of a first embodiment.

2 is a schematic illustration of a lead-out area of an existing ion source system for generating a ribbon beam. Figure 3 is a schematic illustration of a first embodiment of the lead-out region of an ion source system for generating a ribbon beam of the present invention.

Figure 4 is a schematic illustration of a second embodiment of the lead-out region of an ion source system for generating a ribbon beam of the present invention.

Figure 5 is a schematic illustration of a third embodiment of the lead-out region of an ion source system for generating a ribbon beam of the present invention.

Figure 6 is a schematic illustration of a second embodiment of a discharge vessel and cathode unit of an ion source system for producing a ribbon beam of the present invention.

Figure 7 is a schematic illustration of a third embodiment of a discharge vessel and cathode unit of an ion source system for producing a ribbon beam of the present invention. detailed description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 1 and FIGS. 3-7, the hot cathode ion source system for generating a ribbon beam of the present invention first includes a discharge chamber 1 having a plasma 6 therein, a cathode unit, and an extraction as in the prior art. system. The cathode unit is also composed of a hot cathode 2 and a pair of cathodes 3, wherein the filaments 4 are also provided in the hot cathode 2. The take-up system also has a lead-out area (the lead-out areas are indicated by dashed boxes in Figures 3, 4 and 5), and the lead-out area is also provided with a lead-out seam but differs from the prior art in that: In the present invention, the number of the take-up slits 5 is increased by two or more, preferably two or three, and the lead-out slits are disposed in parallel with each other in the lead-out area, for example, FIG. 3, FIG. 4 and FIG. Shown. It should be noted that "parallel to each other" herein includes both the cases where the lead-out slits are strictly parallel to each other, and the case where the lead-out slits are approximately parallel to each other.

Compared with the manner in which only one lead-out slit is provided, the effective area actually used for extracting the beam current in the present invention is significantly increased, and in the case where the plasma concentration in the discharge chamber remains unchanged, it is apparent that the bundle can be bowed out. An ion beam with a greater flow intensity.

Further, since ions are extracted from the discharge cell 1 under the electric field of the extraction system, they tend to appear to have a higher ion density at the center portion and a lower ion density at the edge portion. This will result in a beam intensity that is not uniform enough. Therefore, in order to reduce such naturally occurring unevenness as much as possible, when the number of the lead-out slits 5 reaches four or more, it is preferable to design that the gap between the lead-out slits at the central portion of the lead-out area is larger than a gap between the lead-out seams at the edge portion of the lead-out area; and/or, when the number of the lead-out slits 5 reaches three or more, it is preferably designed as a slit width of the lead-out slit at the central portion of the lead-out area It is smaller than the slit width of the take-up slit at the edge portion of the lead-out area.

However, the intensity of the beam between the larger beamlets drawn from each of the take-up slits 5 is obviously less than The intensity of the beam inside each of the larger beamlets, and therefore, in order to further fine-tune the beam intensity distribution of the entire ion beam, a plurality of extraction holes 7 may be provided at the gaps between the extraction slits. In this way, while each of the take-up slits draws a larger beamlet, each of the outlets 7 will also draw a smaller beamlet, which will be able to match the original bundle well. The region of lower flow intensity is compensated for reinforcement so that the extracted ribbon beam as a whole has an extremely high beam intensity uniformity across the beam cross section.

The specific shape, the number, the size, the position and the like of the lead-out holes 7 are not limited by the present invention. Those skilled in the art can specifically design the lead-out holes according to the specific conditions of the beam intensity distribution of the ion beam. The parameters are used to appropriately compensate for the region of the ion beam with low beam intensity, thereby obtaining an ion beam with uniform beam intensity. Of course, the present invention is not only applicable to the case of generating a uniform beam current. When there is a special requirement for the beam intensity distribution of the ion beam, the shape, the number, the size, and the size of the extraction hole can be specifically designed according to the special requirement. The position is such that the extracted ion beam satisfies the particular beam intensity distribution. The specific design process of the above various parameters for the extraction holes is easy for those skilled in the art, and therefore will not be described herein. The shape of the lead-out holes 7 may be, for example, a circle (as shown in FIG. 4), various regular polygons, an ellipse (as shown in FIG. 5), a rectangle, or the like. Of course, in one embodiment, It is possible to use a single shape of the extraction holes 7 or a plurality of shapes of the extraction holes 7.

Also, since ions are extracted from the discharge cell 1 under the electric field of the extraction system, they tend to exhibit a higher ion density at the center portion and a lower ion density at the edge portion, so that further Preferably, the naturally occurring unevenness is reduced as much as possible, and the lead holes 7 are preferably designed such that the size of the lead-out hole at the central portion of the lead-out area is smaller than the size of the lead-out hole at the edge portion of the lead-out area Dimensions, as shown in FIG. 5; and/or, the distribution density of the extraction holes at the central portion of the lead-out area is smaller than the distribution density of the extraction holes at the edge portions of the lead-out area, as shown in FIG.

In order to increase the beam intensity of the extracted ion beam, in addition to increasing the effective area actually used to extract the beam, it is further considered to increase the concentration of the plasma 6 in the discharge cell 1, which This can be achieved by designing more than two of the cathode units, wherein two of the cathode units are preferably employed. When the number of cathode units is increased, the following benefits will be realized -

1. Increasing the density and total amount of the plasma 6 in the discharge cell 1, under the premise that the extraction capacity of the extraction system in the present invention has been greatly improved, the two effects are superimposed on each other, and obviously will be more greatly Increase the beam intensity of the extracted ion beam.

2. More cathode units will distribute the area of the discharge chamber 1 that is exposed to the hot cathode and the cathode more widely, which will cause ions to be deviated from the central portion when being extracted from the discharge chamber 1. It is also possible to obtain a higher beam intensity, thereby improving the natural non-uniformity at the source when the beam is taken out.

3. In some applications, if the hot cathode ion source system of the present invention only needs to draw a beam of the same intensity as the existing design, the operating voltage of the hot cathode and many related components such as the cathode can be reduced relative to the existing equipment. And the working current, so as to extend the life of the ion source system.

4. The present invention does not change the size of each cathode unit, so the hot cathode ion source system can still complete the preparation process from startup to stable operation in the original time; if the existing design is used to forcibly introduce the magnitude of the present invention The beam intensity means that the size of a single cathode unit has to be greatly increased, which undoubtedly significantly slows down the ion source system from start-up to stable preparation.

Hereinafter, the present invention will be exemplified only by the embodiments 1 to 6. In these examples, the sizes of the respective slits are exemplarily set to be equal, but the present invention is not limited by the setting.

Example 1

The design of the cathode unit in this embodiment is still as shown in FIG. 1 , which is the same as the prior design, and the design of the lead-out area of the lead-out system is as shown in FIG. 3 , wherein the lead-out area is designed with two mutual Parallel extraction slits are used to increase the beam intensity of the extracted ion beam.

Example 2

The design of the cathode unit in this embodiment is still as shown in FIG. 1, and the design of the lead-out area of the extraction system is as shown in FIG. 4 or FIG. In this embodiment, on the basis of the embodiment 1, a plurality of extraction holes are further added at the gap between the two lead-out slits, and are located at the center of the lead-out area. The size or distribution density of the extraction holes at the portion is smaller than the size or distribution density of the extraction holes at the edge portion of the extraction region, thereby further fine-tuning the beam intensity distribution of the extracted ion beam, thereby obtaining a more uniform beam intensity distribution. A uniform ion beam. The design of the cathode unit in this embodiment is as shown in FIG. 6, and the design of the lead-out area of the extraction system is still as shown in FIG. The embodiment further increases the design number of the cathode unit to two on the basis of the embodiment 1, and the hot cathode 2 of the two cathode units is located on the same side of the discharge chamber 1, thereby improving the discharge chamber 1 The concentration and total amount of the plasma 6 in it, thereby further increasing the beam intensity of the extracted ion beam, and since the two cathode units are compared to the single cathode unit, the discharge chamber 1 can be in the longitudinal direction of FIG. The larger of the regions acts to also improve the natural inhomogeneity of the beam intensity distribution of the extracted ion beam.

Example 4

The design of the cathode unit in this embodiment is still as shown in Fig. 6, and the design of the lead-out area of the take-up system is still as shown in Fig. 4 or Fig. 5. In this embodiment, on the basis of Embodiment 3, a plurality of extraction holes are further added at the gap between the two lead-out slits, and the size or distribution density of the lead-out holes located at the central portion of the lead-out area is smaller than that at the lead-out The size or distribution density of the extraction holes at the edge portions of the region is used to further finely adjust the beam intensity distribution of the extracted ion beam, thereby obtaining an ion beam having a more uniform beam intensity. The design of the cathode unit in this embodiment is as shown in Fig. 7, and the design of the lead-out area of the take-up system is still as shown in Fig. 3. This embodiment changes the design direction of the two cathode units on the basis of Embodiment 3 such that their hot cathodes 2 are respectively located on the opposite sides of the discharge cells 1. According to the common knowledge in the art, the size of the pair of cathodes 3 can be appropriately reduced without changing the extraction effect, so that the embodiment can reduce the discharge chamber 1 in comparison with the embodiment 3. The design dimensions in the longitudinal direction of 7 and correspondingly reduce the gap between the two extraction slits, thereby improving the uniformity of the extracted ion beam. Example 6

The design of the cathode unit in this embodiment is still as shown in Fig. 7, and the design of the lead-out area of the take-up system is still as shown in Fig. 4 or Fig. 5. In this embodiment, a plurality of extraction holes are further added to the gap between the two lead-out slits according to the embodiment 5, and the size or distribution density of the lead-out holes located at the central portion of the lead-out area is smaller than the lead-out The size or distribution density of the extraction holes at the edge portions of the region is used to further finely adjust the beam intensity distribution of the extracted ion beam, thereby obtaining an ion beam having a more uniform beam intensity.

In summary, the hot cathode ion source system for generating a ribbon beam of the present invention can not only significantly increase the beam intensity of the extracted ion beam, but also significantly increase the beam intensity distribution of the extracted ion beam. Uniformity also ensures the optical quality of the extracted ion beam.

While the invention has been described with respect to the embodiments of the present invention, it is understood that the scope of the invention is defined by the appended claims. A person skilled in the art can make various changes or modifications to these embodiments without departing from the spirit and scope of the invention, and such modifications and modifications are intended to fall within the scope of the invention.

Claims

What is claimed is: 1. A hot cathode ion source system for generating a ribbon beam current system, the hot cathode ion source system comprising a discharge chamber, a cathode unit comprising a hot cathode and a pair of cathodes, and an extraction system, the extraction system having A lead-out area is provided with a lead-out slit, characterized in that the number of the lead-out slits is two or more, and the lead-out slits are parallel to each other in the lead-out area.

2. A hot cathode ion source system for producing a ribbon beam flow according to claim 1, wherein the number of the extraction slits is two or three.

3. The hot cathode ion source system for generating a ribbon beam flow according to claim 1, wherein the number of the extraction slits is four or more, and between the extraction slits at a central portion of the lead-out area The gap is larger than the gap between the lead slits at the edge portion of the lead-out area; and/or the number of the lead-out slits is three or more, and the slit width of the lead-out slit at the central portion of the lead-out area is smaller than The slit width of the lead slit at the edge portion of the lead-out area.

The hot cathode ion source system for generating a ribbon beam according to any one of claims 1 to 3, wherein a plurality of extraction holes are provided in the gap between the extraction slits.

5. The hot cathode ion source system for generating a ribbon beam according to claim 4, wherein the outlet hole has a circular shape, a regular polygon shape, an elliptical shape or a rectangular shape.

6. The hot cathode ion source system for generating a ribbon beam according to claim 4, wherein a size of the extraction hole at a central portion of the lead-out area is smaller than an edge portion of the lead-out area. The size of the lead-out hole; and/or the distribution density of the lead-out hole at the central portion of the lead-out area is smaller than the distribution density of the lead-out hole at the edge portion of the lead-out area.

A hot cathode ion source system for producing a ribbon beam according to any one of claims 1 to 6, wherein the number of cathode units is one.

The hot cathode ion source system for producing a ribbon beam according to any one of claims 1 to 6, wherein the number of the cathode units is two or more.

9. The hot cathode ion source system for generating a ribbon beam according to claim 8, wherein The sign is that the number of cathode units is two.

10. A hot cathode ion source system for generating a ribbon beam flow according to claim 9, wherein the hot cathodes of the two cathode units are located on the same side of the discharge chamber.

11. The hot cathode ion source system for generating a ribbon beam according to claim 9, wherein the hot cathodes of the two cathode units are respectively located on opposite sides of the discharge chamber.