CN107633992B

CN107633992B - Ion source with double thermionic electron source and its thermionic electron generating method

Info

Publication number: CN107633992B
Application number: CN201710500979.2A
Authority: CN
Inventors: 粘俊能
Original assignee: Chenshuo International Co ltd
Current assignee: Entegris Inc
Priority date: 2016-07-18
Filing date: 2017-06-27
Publication date: 2020-07-28
Anticipated expiration: 2037-06-27
Also published as: TW201804505A; CN107633992A; TWI592972B; CN207165515U

Abstract

The invention discloses an ion source with double thermionic electron sources and a thermionic electron generating method thereof, wherein the method mainly reduces the voltage of an arc power supply provided for an arc chamber body, so that the voltage is within the voltage range of 20V to 45V, and the energy of thermionic electrons and ions after passing through an accelerating electric field between the body and a first thermionic electron source and between the body and a second thermionic electron source is weakened; the low-energy ions can cause a relatively mild splashing effect on each of the first and second thermal electron sources, so that the service life of each of the first and second thermal electron sources is prolonged, and the low-energy thermal electrons can prevent the thermal electrons from impacting ionized ions for many times, thereby effectively reducing unnecessary divalent or trivalent positively charged ions and relatively increasing the proportion of required ions in the ion beam (extraction current).

Description

Ion source with double thermionic electron source and its thermionic electron generating method

Technical Field

The present disclosure relates to ion sources, and more particularly to an ion source with dual thermionic electron sources.

Background

Ion implanters are used in semiconductor manufacturing processes to implant ions into regions of semiconductor wafers, and ion sources in the ion implanters are used to generate ion beams for ion implantation, and there are two types of ion sources currently in use for generating different types of hot electrons: one of them is a Bernas Ion Source, and the other is an Indirectly Heated Cathode Ion Source (IHC Ion Source).

Referring to FIG. 6A, the thermionic electron source of the Berner ion source directly employs a filament 62, the filament 62 passing inwardly from one side of an outer shell 61 of an arc chamber 60 and secured to an inner plate 611 of that side. When a filament power supply unit 70 provides current to the filament 62, the temperature of the filament 62 will increase, and electrons will be generated when the temperature of the filament 62 increases to reach a certain high temperature (e.g., the temperature is greater than 1000 ℃). At this time, the positive and negative electrodes of an arc power supply unit 72 are respectively coupled to the inner plate 611 of the arc chamber 60 of the ion source and the filament 62, so as to form an accelerating electric field of electrons in the arc chamber 60, so as to attract the electrons of the filament 62 to the arc chamber 60, and ionize the dopant source gas in the arc chamber 60 to generate different kinds of ions. Since the voltage supplied to the inner plate 611 of the arc chamber 60 by the arc power supply unit 72 falls within the voltage range of 60V to 150V, the energy of electrons passing through the accelerating electric field is greatly increased to become high-energy thermal electrons, and the high-energy thermal electrons can impact the dopant source gas many times to generate positive or negative ions with different valence; wherein the positively charged ions are also attracted by the accelerating electric field to increase the energy of the outward emission. High energy ions may sputter (splash) the filament 62 multiple times, causing the filament 62 to be damaged and replaced.

To increase the lifetime of the filament 62, the arc chamber 60' of the indirectly heated cathode ion source shown in FIG. 6B further comprises a metal shield covering the filament 62 and coupled to the negative electrode of the arc power supply unit 72, thereby serving as a cathode 621 (hereinafter referred to as "cathode"). When the filament 62 is heated to emit electrons, the cathode 621 is connected to the positive electrode of a bias current power supply unit 71 to have a positive potential so as to accelerate and attract the electrons emitted from the filament 62, and the electrons with increased energy continuously collide with the outer side of the cathode 621, so that the temperature of the cathode 621 is increased; similarly, when the cathode 621 is heated to a certain temperature and emits electrons, the electrons are attracted by the accelerating electric field formed by the voltage supplied by the arc power supply unit 72, become high-energy thermal electrons, and are emitted toward the arc chamber 60'. Since the high energy thermionic electrons ionize the dopant source gas in the arc chamber 60' to generate positively and negatively charged ions, the positively charged ions are also accelerated by the accelerating electric field and emitted toward the cathode 621 in a reverse direction, so as to sputter the inner side of the cathode 621, and although the filament 62 is prevented from being sputtered by the ions directly, the cathode 621 is broken down after a while and needs to be replaced; therefore, the arc chambers 60, 60' of the single set of thermionic electron source structures of FIGS. 6A and 6B have a discharge space with a concentrated ion concentration on the side where the thermionic electron source is located, and the closer the thermionic electron source is located, the higher the ion concentration, showing a single high concentration ion sputtering effect.

In the structure of the thermionic source shown in fig. 6A or fig. 6B, which is a consumable item for the ion source, many manufacturers have been invested in developing a technique for prolonging the service life of the thermionic source, as disclosed in taiwan patent publication No. I450303, "cathode of indirectly heated electrode ion implanter" (as shown in fig. 7), a cathode 80 is thickened toward the middle front end 801 of a Repeller 81(Repeller) on the other side of the arc chamber, so that the time of erosion by the ion spray base can be prolonged, and the service life can be prolonged relatively. Further, as shown in the utility model patent of "ion source and ion implanter" of chinese continental publication No. CN203631482 (as shown in fig. 8), the diameter and thickness of the front end 801 'of the cathode 80' are also increased, so as to increase the service life of the cathode. Taiwan publication No. I493590 discloses a device and method for prolonging the service life of an ion source, wherein as shown in fig. 9, two or more groups of thermal electron sources 80a and 80b are disposed in an arc chamber, only one group of thermal electron sources 80a is used, and a second group of thermal electron sources 80b is switched to be used after the group of thermal electron sources 80a fails, and ionization can be continued only by changing the relative position of a repeller 81 in cooperation with a rotary structure 811; therefore, the invention of patent I493590 actually prolongs the time for replacing the thermal electron sources 80a, 80b by switching the different sets of thermal electron sources 80a, 80b, and the service life of the single set of thermal electron sources is not prolonged accordingly.

As can be seen from the above description, the current technology for actually prolonging the service life of the thermionic electron source mainly improves the structure, but it is necessary to produce cathodes with different sizes, and the time for actually prolonging the service life is limited. For example, the technique proposed in patent No. I493590 can prolong the time for replacing the thermionic source in the ion source, but needs to monitor whether the thermionic source in use has failed, so as to switch to another spare thermionic source in real time; in addition, a rotating structure is further added in the arc chamber to match different positions of the thermal electron source to maintain normal use. Therefore, how to prolong the service life of the thermal electron source on the premise of not changing the structural design of the arc chamber is a technical problem to be solved in the field.

Disclosure of Invention

In view of the previously disclosed technology for prolonging the service life of the thermal electron source of the conventional ion source, the structure of an arc chamber needs to be changed; therefore, the main objective of the present invention is to provide an ion source with dual hot electron sources and a hot electron generation method thereof, which can prolong the service life of the hot electron source without changing the arc chamber structure.

The main technical means used to achieve the above object is to make the ion source with dual thermionic electron source comprise:

an arc chamber comprising:

a body having a discharge space;

a first thermal electron source penetrating from a first side of the body and fixed to the first side in an electrically insulated manner so as to be exposed in the discharge space of the body; and

a second thermal electron source penetrating from a second side of the body and electrically insulated and fixed to the second side to be exposed in the discharge space of the body; and

a power supply device, comprising:

a heating power supply unit coupled to the first and second thermal electron sources to form a current loop; and

a low voltage arc power supply unit coupled to the body of the arc chamber and the first and second thermal electron sources; wherein the low-voltage arc power supply unit simultaneously provides an output voltage falling between 20V and 45V to the first and second thermal electron sources.

The present invention mainly reduces the voltage of the low voltage arc power supply unit of the ion source within the voltage range of 20V to 45V, so that the accelerating electric field between the body of the arc chamber and the first and second thermal electron sources provides energy reduction for electrons and ions. Because the emission energy of the ions generated in the arc chamber body towards the first and second thermal electron sources is weakened, the splashing of each first and second thermal electron source is reduced, and the service life of each first and second thermal electron source is relatively prolonged. Furthermore, because the electrons generated by the first and second thermal electron sources have weaker energy through the accelerating electric field, the low-energy thermal electrons can be prevented from impacting ionized ions for many times, so that unnecessary divalent or trivalent positively charged ions can be effectively reduced, and the proportion of useful ions in the ion beam (extraction current) is relatively increased.

The main technical means of the present invention to achieve the above object is to provide an ion source comprising an arc chamber, a body of the arc chamber having a discharge space, wherein two thermal electron sources are respectively disposed through two sides of the body in an electrically insulated manner; wherein the hot electron generation method comprises:

providing a heating power supply for the two thermal electron sources to heat each thermal electron source to a first predetermined temperature and then emit thermal electrons; and

providing an arc power supply for the body and each of the thermal electron sources to accelerate and attract the thermal electrons emitted by the two thermal electron sources to a discharge space of the arc chamber; wherein the arc power supply provides a voltage falling between the voltage range of 20V to 45V.

The voltage of the arc power supply is mainly reduced to fall between the voltage range of 20V to 45V, so that the energy provided by the accelerating electric field between the arc chamber body and the first and second thermal electron sources for electrons and ions is weakened, the sputtering effect of low-energy ions on the first and second thermal electron sources is relieved, the service life of the first and second thermal electron sources is prolonged, the low-energy thermal electrons can avoid the thermal electrons from impacting ionized ions for many times, unnecessary divalent or trivalent positively charged ions are effectively reduced, and the proportion of required ions in an ion beam (extraction current) is relatively improved.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

FIG. 1: the invention relates to a three-dimensional appearance diagram of an ion source;

FIG. 2A: the invention is a schematic diagram of the electrical connection between the arc chamber of a bernas ion source and a power supply device;

FIG. 2B: the invention is a schematic diagram of electrical connection between an arc chamber of an indirect heating cathode ion source and a power supply device;

FIG. 3: FIG. 1 is a partial cross-sectional view;

FIG. 4: the invention is a three-dimensional appearance diagram of a first preferred embodiment of a heat dissipation device;

FIG. 5: the perspective view of the second preferred embodiment of the heat dissipation device of the present invention;

FIG. 6A: there is a three-dimensional appearance diagram of an indirect heating cathode ion source;

FIG. 6B: schematic diagram of electrical connection between arc chamber of conventional indirect heating cathode ion source and power supply device

FIG. 7: taiwan publication No. I450303;

FIG. 8: fig. 3 of the chinese mainland publication No. CN203631482 utility model patent;

FIG. 9: taiwan patent No. I493590, fig. 1A.

Wherein the reference numerals

1 ion source

10. 10' arc chamber

100 discharge space 100a ion beam

11 bottom air intake hole of outer shell 111

12. 12a, 12b inner plates 14, 14' thermal electron generating elements

141 filament 142 cathode

20. 20' heat sink 21 heat sink body

211 top surface 212 bottom surface

213 side 214 short side

215 groove 216 space

22 cooling

medium pipes

221, 222 branch pipes

30 base 301 top surface

31 lower base

40 air inlet pipe

50. 50' power supply device 51 filament power supply unit

52 bias current power supply unit 53 low voltage arc power supply unit

60. 60' arc chamber 61 housing

611 inner plate 62 filament

621 cathode 63 repeller

70 filament power supply unit 71 bias current power supply unit

72 arc power supply unit

80. 80' cathode 80a, 80b thermionic source

801. 801' front 81 repeller

811 rotating structure

Detailed Description

The invention provides an ion source with double thermionic sources and a thermionic generating method thereof, which can prolong the service life of the thermionic sources on the basis of not changing the structure of the thermionic sources in the ion source of an ion implanter.

Referring to fig. 1, a perspective view of an ion source 1 according to the present invention is shown, wherein a heat dissipation device 20 and an arc chamber 10 are sequentially stacked on a top surface 301 of a base 30; referring again to FIG. 2A, the first preferred embodiment of the arc chamber 10 of the present invention is further electrically connected to an external power supply 50, the arc chamber 10 comprising a body, a first source 14a of thermal electrons and a second source 14b of thermal electrons; the power supply device 50 used in this embodiment includes a filament power supply unit 51 and a low-voltage arc power supply unit 53.

Referring to fig. 2A and 3, in the present embodiment, the main body includes a housing 11 and a plurality of

inner plates

12, 12A, 12b, the first thermionic source 14a penetrates the housing 11 and the corresponding inner plate 12A from a first side of the main body and is electrically insulated and fixed on the first side of the main body, and the second thermionic source 14b penetrates the housing 11 and the corresponding inner plate 12b from a second side of the main body and is electrically insulated and fixed on the second side of the main body. In the present embodiment, each of the first and second

thermal electron sources

14a, 14b includes a filament 141, and the filament 141 is directly exposed to the discharge space 100 of the arc chamber 10.

The filament power supply unit 51 is coupled to the filaments 141 of the first and second

thermal electron sources

14a, 14b to form a current loop. The low-voltage arc power supply unit 53 is coupled to the inner plate 12 of the body and the first and second

thermal electron sources

14a, 14 b; wherein the low voltage arc power supply unit 53 provides an output voltage falling between the voltage range of 20V to 45V. In the present embodiment, one end of the filament 141 of the first and second

thermal electron sources

14a, 14b is connected to each other, and the other end is connected to the positive electrode (+), the negative electrode (-) of the filament power supply unit 51 to form the current loop, the negative electrode (-) of the low voltage arc power supply unit 53 is connected to the current loop to couple to the first and second

thermal electron sources

14a, 14b, and the positive electrode (+) is coupled to the inner plate 12 of the body.

In the present embodiment, although the arc chamber 10 includes first and second

thermal electron sources

14a, 14b, one of the thermal electron sources 14b is mounted in a repeller position in an existing arc chamber; thus, the body structure of the arc chamber 10 of the present invention is not changed. When the filament power supply unit 51 provides current to the current loop, the filaments 141 of the first and second

thermal electron sources

14a and 14b are heated to a certain temperature and emit thermal electrons into the discharge space 100 of the arc chamber 10. Then, when the low voltage arc power supply unit 53 provides an output voltage in the voltage range of 20V to 45V, an accelerating electric field is established between each filament 141 and each

inner plate

12, 12a, 12b, so that electrons generated by the filaments 141 at both sides of the body are accelerated and emitted into the discharge space 100 of the arc chamber 100, and several ions are generated by ionizing the introduced dopant source gas.

Because the invention reduces the voltage of the arc power provided to the

inner plates

12, 12a, 12b of the arc chamber, the energy provided to electrons and ions by the accelerating electric field between the body of the arc chamber 10 and the first and second

thermal electron sources

14a, 14b, respectively, is reduced; wherein the low energy ions reduce sputtering of the filament 141 of each of the first and second

thermal electron sources

14a, 14b, thereby extending the life of the filament 141. Similarly, because the energy of the thermal electrons is attenuated after the impact, the energy of the thermal electrons with low energy is further reduced after one impact, thereby reducing the chance of impacting divalent or trivalent ions again for monovalent ions, effectively reducing unnecessary divalent or trivalent positively charged ions, and relatively increasing the proportion of ions required in the ion beam (extraction current). The first and second

thermal electron sources

14a, 14b are respectively disposed on the first and second sides of the arc chamber 10, so that thermal electrons are emitted to the discharge space 100 at the same time, thereby more uniformly ionizing the dopant source gas in the discharge space 100.

In summary, the method for generating hot electrons for an ion source according to the first embodiment of the present invention includes: providing a heating power supply to the two filaments 141, so that each filament 141 generates electrons after being heated to a certain temperature, and emits thermal electrons from two sides of the body to the discharge space 100; and providing an arc power supply to the main body and each of the filaments 141, wherein the main body is coupled to a positive electrode of the arc power supply to accelerate and attract electrons generated by the filaments 141 on both sides; wherein the arc power supply provides a voltage falling between the voltage range of 20V to 45V.

Referring to FIG. 2B, a second preferred embodiment of the arc chamber 10 ' of the present invention is shown, which is substantially the same structure as the arc chamber 10 of the first preferred embodiment shown in FIG. 2A, except that each of the first and second thermal electron sources 14a ', 14B ' further includes a cathode 142 for covering its corresponding filament 141 to prevent the filament 141 from being directly exposed to the discharge space 100; in addition, the power supply device 50 'used in conjunction with the arc chamber 10' of the present embodiment further includes a bias current power supply unit 52. The cathodes 142 of the first and second thermal electron sources 14a ', 14 b' are coupled to the positive electrode (+) of the bias power supply unit 52 and the negative electrode (-) of the low-voltage arc power supply unit 53, respectively. The negative electrode (-) of the bias current power supply unit 52 is connected to the current loop, i.e., the filament 141 coupled to the first and second thermal electron sources 14a ', 14 b'.

When the filament power supply unit 51 outputs current to the current loop, the filaments 141 of the first and second thermal electron sources are heated to a first predetermined temperature, and then electrons are emitted to the discharge space; at this time, the positive and negative electrodes of the bias current power supply unit 52 are coupled to the cathode 142 and the filament 141, respectively, so as to establish an accelerating electric field between each cathode 142 and the corresponding filament 141, and attract the filament 141 to emit thermal electrons to impact the corresponding cathode 142, so as to heat the cathode 142; thermal electrons are emitted into the arc chamber 100 after the cathode 142 is heated to a second predetermined temperature. The positive and negative electrodes (+), (-) of the low-voltage arc power supply unit 53 are coupled to the

inner plates

12, 12a, 12b and the cathode 142, respectively; wherein the low voltage arc power supply unit 53 provides an output voltage falling within a voltage range of 20V to 45V, and an accelerating electric field is established between each cathode 142 and each

inner plate

12, 12a, 12b, so that thermal electrons of the cathode 142 are accelerated and emitted into the discharge space 100, and the introduced dopant source gas is uniformly ionized to generate a plurality of ions.

In summary, the ion source hot electron generating method according to the second embodiment of the present invention includes: providing a heating power supply to the two filaments 141, so that each filament 141 emits electrons after being heated to a first predetermined temperature; providing a bias current power to each cathode 142 and the corresponding filament 141, wherein each cathode 142 is coupled to the positive electrode of the bias current power to attract electrons emitted from the filament 141 to increase the temperature of the cathode 142, and when reaching a second predetermined temperature, thermal electrons are emitted to both sides in the arc chamber 10'; and providing an arc power to the

inner plates

12, 12b and the cathodes 142, wherein the

inner plates

12, 12b are coupled to the positive electrode of the bias current power to accelerate the attraction of hot electrons on both sides; wherein the arc power supply provides a voltage falling between the voltage range of 20V to 45V.

Suitable dopant source gases for use in the present invention may be one of germanium tetrafluoride, germane, boron trifluoride, diborane, silicon tetrafluoride, silane, arsine or phosphine. In addition, the dopant source gas suitable for the present invention may also be a dopant composition gas synthesized from a dopant gas and a supplementary gas, wherein the dopant gas is germanium tetrafluoride, germane, boron trifluoride, diborane, silicon tetrafluoride, silane, arsine or phosphine, and the supplementary gas is argon, hydrogen, nitrogen, helium, ammonia, fluorine or xenon; each doping gas can be mixed with one of the supplementary gases to form the doping component gas, so as to be used as the doping source gas of the invention; alternatively, each of the dopant gases and one of the supplementary gases may be used separately and co-flowed into the arc chamber to form a co-flow gas, also for use as the dopant source gas in the present invention.

The following further illustrates that the arc source voltage obtained by experimental measurements on several different doping source gases disclosed above is preferably:

when the dopant source gas introduced from the arc chamber contains boron trifluoride (BF3) or the dopant source gas is boron trifluoride (BF3), the voltage of the arc power supply is 30V to 45V.

When the doping source gas introduced from the arc chamber contains arsine (AsH3) or phosphine (PH3), the voltage of the arc power supply is 25V-40V.

When the doping source gas introduced from the arc chamber contains silicon tetrafluoride (SiF4), the voltage of the arc power supply is 25V-40V.

Therefore, the invention can relatively weaken the energy of the hot electrons generated by the hot electron generating element by the accelerating electric field established by the lower arc power voltage. Theoretically, the energy required by the hot electron to collide with the outermost first valence electron of the dopant source gas is not high, and only the energy of the hot electron is provided by the 8V to 15V accelerating electric field, but if the hot electron further collides with the second valence electron of the dopant source gas, the hot electron needs the accelerating electric field of more than 22V to provide more energy. However, the impact direction of the thermal electrons cannot be controlled, so that there is a considerable chance that at least the first valence electrons, which are the outermost electrons of the dopant source gas, will be impacted by adjusting the voltage of the arc power source to fall between the voltage range of 20V and 45V, based on the impact force of the thermal electrons and the extraction current (ion beam) of a certain magnitude; therefore, although the voltage of the arc power source is reduced compared with the conventional ion source, the energy for producing the thermal electrons is relatively low, and the chance of hitting out divalent or trivalent ions is reduced because the energy of the thermal electrons with lower energy is attenuated after the thermal electrons hit.

Boron trifluoride is used as an ionization agent which is introduced into an arc chamber (a single-group thermal electron source) of the second embodiment of the invention and an arc chamber (a single-group thermal electron source) of the conventional ion source; wherein, the voltage of the arc power supply of the invention is set to be 40V, the voltage of the arc power supply of the existing arc chamber is 85V, six groups of arc power supply currents from small to large are adjusted (power is increased in sequence), and the extraction current (ion beam) of the arc chamber and the ROI current of useful univalent boron ions (B +) in the ion beam are measured; wherein the ROI current refers to the terminal current available for implantation on the wafer surface and is called ROI current (ROI), and the actual measurement results are shown in the following table.

Watch 1

As can be seen from the above table, when the voltage of the arc power supply is set to 40V and the voltage of the conventional arc power supply is set to 85V, the ROI current value of the monovalent boron ions of the present invention is higher than that of the conventional ion source in the same extraction currents (20mA, 25mA, 30mA, 35mA, 40mA, and 45mA) in each set, which are measured by introducing boron trifluoride into the arc chamber.

As for the life of the thermal electron source, the same previous uncovering conditions produced 35mA extraction current and the cathode thickness of 0.3 inches (inch) was used for the test, if as shown in table two below, the thickness of the cathode of the present invention decreased from 0.3 inches to 0.28 inches over 45 days, whereas the existing arc chamber started with a 0.3 inch cathode and 0.0 inches (punctured) for only 29 days; therefore, the present invention can effectively prolong the service life of the cathode.

Watch two

The foregoing measurement data was obtained by measuring the arc chamber of the second preferred embodiment of the present invention with a single set of thermal electron sources, such as the arc chamber 10 ' shown in FIG. 2B with two sets of thermal electron sources 14a ', 14B ', which can measure a higher ROI current value of monovalent boron ions than the previous table due to the increased number of total generated thermal electrons; in addition, compared to an arc chamber with ion concentration concentrated on one side of a single set of thermal electron source, the two sets of thermal electron sources 14a ', 14B' of fig. 2B of the present invention can uniformly distribute ions generated overall on both sides of the discharge space 100, and compared to a single high concentration ion sputtering effect of an arc chamber with a single set of thermal electron source, the arc chamber 10 'of fig. 2B of the present invention can effectively distribute the high concentration ion sputtering effect to the two sets of thermal electron sources 14 a', 14B 'to reduce the sputtering effect by half, so as to greatly prolong the number of days of use of the cathode 142 shown in table two, and also to prolong the life of the arc chamber 10'.

Referring to fig. 1 and 3, the ion source 1 of the present invention uses a plurality of elastic hook components to tightly buckle the heat dissipation device 20 and the arc chamber 10 on the base 30, that is, four equidistant L-shaped fixing members 32 are screwed on the lower substrate 31 of the base 30, each fixing member 32 is hooked with one end of a spring 33, the other end of the spring 33 is hooked on one end of a hook strip 34, the other end of the hook strip 34 is formed with a hook portion 341 to hook two opposite long sides of the extraction electrode plate 13 of the arc chamber 10, and after being buckled, the arc chamber 10 and the heat dissipation device 20 below the arc chamber can be tightly buckled on the top surface 301 of the base 30 by the restoring force of the spring 33.

When the power of the arc power supply is increased, the temperature of the arc chamber is increased, so that the invention uses the heat sink 20 with high heat dissipation, and the heat sink 20 with high heat dissipation comprises a heat sink body 21 and at least one cooling medium pipe 22. The bottom surface 212 of the heat dissipating body 21 is disposed on the top surface 301 of the base 30, and the top surface 211 thereof is flush with the bottom surface of the arc chamber housing 11, and as shown in fig. 4, two opposite short sides 214 of the heat dissipating body 21 of the present embodiment are respectively tapered downward and inward from the top surface 211, and the bottom surface 212 of the heat dissipating body 21 is smaller than the top surface 211; as shown in fig. 5, in another embodiment of the heat dissipating device 20', the lower portions of two opposite short sides 214 of the heat dissipating body 21 are recessed downward to form a space 216, and the bottom surface 212 of the heat dissipating body 21 is smaller than the top surface 211; compared to the embodiment of the heat dissipation device 30 shown in fig. 5, the heat conducted from the arc chamber 10 to the top surface 211 of the heat dissipation body 21 can be rapidly concentrated to the middle of the heat dissipation body 21. Furthermore, in order not to interfere with the air inlet pipe 40, as shown in fig. 3, a concave groove 215 is concavely disposed on a side 213 of the heat dissipation body 21 corresponding to the air inlet pipe 40, the concave groove 215 penetrates through the top surface 211 and the bottom surface 212 of the heat dissipation body 21, and since there is a gap between the outer wall of the air inlet pipe 40 and the inner wall of the concave groove 215, the air inlet pipe 40 is not in contact with the heat dissipation body 21. Each cooling medium pipe 22 passes through the heat dissipating body 21, and passes through two

branch pipes

221, 222 from the bottom of the heat dissipating body 21, and is inserted into the base 30 from the top 301 of the base 30 to connect with a cooling medium (not shown). Furthermore, one of the branch pipes 221 serves as a cooling medium inlet pipe; the other branch pipe 222 serves as a discharge pipe for the cooling medium, so that the cooling medium can flow in the cooling medium pipe 22. Preferably, the cooling medium may be a cooling gas or a cooling liquid.

In summary, the heat dissipation devices 20 and 20' of the present invention are mainly flush with the bottom surface of the arc chamber 10, so as to provide a more stable support, provide a higher heat conduction efficiency of the arc chamber by a larger contact area, and cooperate with the flow cooling medium in the cooling medium pipe 22 to rapidly separate the heat of the heat dissipation body 21, so as to achieve a better overall heat dissipation efficiency; moreover, since the heat dissipation devices 20 and 20' are mainly flush with the bottom surface of the arc chamber 10, even though the housing is not easily deformed by heat under high temperature operation, it is able to further avoid blocking the bottom inlet hole of the arc chamber by using some doping gases that are easily cracked by heat.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An ion source having a dual thermionic electron source, comprising:

an arc chamber comprising:

a body having a discharge space;

a power supply device, comprising:

2. The ion source of claim 1 having a dual thermionic electron source, wherein:

the first thermal electron source comprises a filament;

the second thermal electron source comprises a filament, one end of which is connected to one end of the filament of the first thermal electron;

the heating power supply unit comprises a filament power supply unit, and the positive electrode and the negative electrode of the filament power supply unit are respectively connected to the other ends of the filaments of the first and second thermal electron sources to form the current loop; and

the negative electrode of the low-voltage arc power supply unit is connected to the current loop to be coupled with the filaments of the first and second thermal electron sources, and the positive electrode is connected to the body.

3. The ion source of claim 1 having a dual thermionic electron source, wherein:

the first thermal electron source comprises a filament and a cathode covering the filament of the first thermal electron source;

the second thermal electron source comprises a filament and a cathode covering the filament of the second thermal electron source; wherein one end of the filament of the second thermionic electron source is connected to one end of the filament of the first thermionic electron source, and the cathode of the second thermionic electron source is connected to the cathode of the first thermionic electron source;

the heating power supply unit includes:

a filament power supply unit, the positive and negative electrodes of which are connected to the other ends of the filaments of the first and second thermal electron sources, respectively, to form the current loop; and

a bias current power supply unit, the positive electrode of which is connected to one of the cathodes and the negative electrode of which is connected to the current loop to couple with the filaments of the first and second thermal electron sources; and

the negative electrode of the low-voltage arc power supply unit is connected to the positive electrode of the bias current power supply unit to couple with the cathodes of the first and second thermal electron sources, and the positive electrode is connected to the body.

4. The ion source with dual thermionic electron source of any one of claims 1 to 3, wherein:

when the doping source gas introduced from the arc chamber contains boron trifluoride, the output voltage of the low-voltage arc power supply unit is 30V to 45V;

when the doping source gas introduced from the arc chamber contains arsenic hydride or phosphine, the output voltage of the low-voltage arc power supply unit is 25V to 40V; and

when the doping source gas introduced from the arc chamber contains silicon tetrafluoride, the output voltage of the low-voltage arc power supply unit is 25V to 40V.

5. The ion source with dual thermionic electron source of any one of claims 1 to 3, wherein:

when doping source gas mixed by boron trifluoride and supplementary gas is introduced from the arc chamber, the output voltage of the low-voltage arc power supply unit is 30V to 45V;

when doping source gas which is formed by mixing arsenic hydride or phosphine and supplementary gas and is led in from the arc chamber, the output voltage of the low-voltage arc power supply unit is 25V to 40V; and

when doping source gas formed by mixing silicon tetrafluoride and supplementary gas is introduced from the arc chamber, the output voltage of the low-voltage arc power supply unit is 25V to 40V.

6. The ion source of any of claims 1 to 3, further comprising:

a base, the top surface of which is convexly provided with an air inlet pipe; and

and the heat dissipation device is arranged between the top surface of the base and the bottom surface of the body of the arc chamber.

7. The ion source of claim 6, wherein the heat sink comprises:

a heat radiation body, the bottom surface of which is arranged on the top surface of the base, the top surface of which is entirely flat and flatly attached to the bottom surface of the arc chamber body, one side surface of the heat radiation body corresponding to the air inlet pipe is inwards provided with a groove penetrating through the top surface and the bottom surface of the heat radiation body, and the outer pipe wall of the air inlet pipe has a distance with the inner wall surface of the groove; and

at least one cooling medium pipe passing through the heat dissipating body and penetrating through the two branch pipes downwards from the bottom of the heat dissipating body, and each cooling medium pipe is filled with a flowing cooling medium through the two branch pipes.

8. A kind of hot electron producing method of ion source with double hot electron source, the ion source includes an arc chamber, the body of the arc chamber has a discharge space, two hot electron sources are separately set through two sides of the body in electric insulation; wherein the hot electron generation method comprises:

9. The method of claim 8, wherein each of the thermal electron sources comprises a filament exposed to the interior of the body; the method is characterized in that:

in the step of providing the heating power to the two thermal electron sources, the heating power is provided to each filament to emit thermal electrons from two sides of the body to the discharge space; and

in the step of providing the arc power to the body and each of the thermal electron sources, the arc power is provided to the body and each of the filaments.

10. The method of claim 8, wherein each of the thermal electron sources comprises a filament exposed to the inner space of the body and a cathode covering the corresponding filament; the method is characterized in that:

in the step of providing the heating power to the two thermal electron sources, providing the heating power to each filament; and the hot electron generation method further comprises: providing a bias current power supply for each cathode and each filament, wherein each cathode is coupled to the positive electrode of the bias current power supply to attract the thermal electrons emitted by the corresponding filament to increase the temperature of the cathode, and the thermal electrons are emitted to the discharge space when the temperature reaches a second preset temperature; and

in the step of providing the arc power to the body and each of the thermal electron sources, the arc power is provided to the body and each of the cathodes.

11. A thermionic electron generating method of an ion source having a dual thermionic electron source as claimed in any one of claims 8 to 10, wherein:

when the doping source gas introduced from the arc chamber contains boron trifluoride, the voltage of the arc power supply is 30V to 45V;

when the doping source gas introduced from the arc chamber contains arsenic hydride or phosphine, the voltage of the arc power supply is 25V to 40V; and

when the doping source gas introduced from the arc chamber contains silicon tetrafluoride, the voltage of the arc power supply is 25V to 40V.

12. A thermionic electron generating method of an ion source having a dual thermionic electron source as claimed in any one of claims 8 to 10, wherein:

when doping source gas mixed by boron trifluoride and supplementary gas is introduced from the arc chamber, the voltage of the arc power supply is 30V to 45V;

when doping source gas which is formed by mixing arsenic hydride or phosphine and supplementary gas and is led in from the arc chamber, the voltage of the arc power supply is 25V to 40V; and

when a doping source gas formed by mixing silicon tetrafluoride and a supplementary gas is introduced from the arc chamber, the voltage of the arc power supply is 25V to 40V.