Patent Application
20240038499
This application claims priority from Japanese Patent Application No. 2022-122482, filed in the Japanese Patent Office on Aug. 1, 2022, the entire contents thereof being herein incorporated by reference in its entirety.
The present disclosure relates to an ion source used in an ion beam irradiation apparatus and an operating method of the ion source.
In an ion implanter, an ion species is switched depending on a kind of ion implantation process performed by the ion implanter. When the ion species is switched, the type of gas or vapor to be introduced into a plasma chamber is switched. A plasma is generated in the plasma chamber from the switched gas or vapor each time the type of gas or vapor is switched. An ion beam is then extracted from the generated plasma with a desired beam energy.
Some ion implanters may include ion sources having an oven for a solid material. In this ion implanter, it takes time to switch the ion species, and thus frequent switching of the ion species deteriorates a productivity of the ion implanter.
It is an aspect to make it possible to reduce a time required for switching an ion species.
According to an aspect of one or more embodiments, there is provided an ion source comprising a vaporizer which produces a reaction product by supplying, through a first gas supply line to a crucible in which a solid material is installed, a reactive gas that reacts with the solid material, and which vaporizes the reaction product by heating the crucible with a heater; a plasma chamber to which a vapor is supplied from the vaporizer through a vapor supply line, a second gas supply line being connected to the plasma chamber separately from the vapor supply line; and a controller that is configured to control the heater to heat the crucible while a gas is being supplied from the second gas supply line to the plasma chamber and to stop a supply of the reactive gas through the first gas supply line to the crucible.
According to another aspect of one or more embodiments, there is provided an operating method for an ion source comprising a vaporizer that produces a reaction product by supplying, though a first gas supply line to a crucible in which a solid material is installed, a reactive gas that reacts with the solid material, and vaporizes the reaction product by heating the crucible with a heater, a plasma chamber to which a vapor is supplied from the vaporizer through a vapor supply line, a second gas supply line being connected to the plasma chamber separately from the vapor supply line, the operating method comprising heating the crucible by the heater while a gas is being supplied from the second gas supply line to the plasma chamber, and stopping supply of the reactive gas through the first gas supply line to the crucible.
According to yet another aspect of one or more embodiments, there is provided an ion source comprising a vaporizer including a crucible containing a solid material which reacts with a reactive gas which, when heated, generates a vapor; a heater configured to heat the crucible; a plasma chamber communicatively connected to the vaporizer by a vapor supply line and configured to generate a plasma from the vapor or from a source gas supplied thereto; a source gas supply line communicatively connected to the plasma chamber and through which the source gas is supplied to the plasma chamber; a reactive gas supply line communicatively connected to the vaporizer through which the reactive gas is supplied to the vaporizer; and a controller that is configured to control the heater to heat the crucible while supplying the source gas to the plasma chamber through the source gas supply line, and to switch a source of the plasma from the vapor to the source gas by stopping the reactive gas from being supplied through the reactive gas supply line to the crucible.
The above and/or other aspects will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings, in which:
As described above, in an ion implanter, the ion species are switched depending on a kind of ion implantation process. When the ion species is switched, the type of gas or vapor to be introduced into a plasma chamber is switched. A plasma is generated in the plasma chamber for each of the switched gas or vapor. An ion beam is extracted from the generated plasma with a desired beam energy.
Some ion sources include an oven for a solid material. In this ion source, a gas from a gas source and a vapor from an oven are selectively supplied to a plasma chamber as a source of plasma. After the source of plasma is switched from vapor to gas, a heater of the oven is turned off. However, the oven is heated by radiation heat from the plasma chamber. As a result, even though the oven is turned off, a vapor may still be released into the plasma chamber and mix with the gas supplied from the gas source.
As a countermeasure, the oven temperature may be kept at a low temperature using a cooling mechanism so that heat from the plasma chamber is not transferred to the oven and vapor is not supplied from the oven while the plasma is generated based on gas from the gas source.
However, the countermeasure has a disadvantage in a switching time of the ion species increases. The oven temperature is switched from low to high temperature or from high to low temperature so that the oven temperature may reach a predetermined temperature when switching the ion species. Oven temperature control is time-consuming, and this increased time is said to be the cause of prolonged switching of ion species.
Since the time required for oven temperature control increases according to the number of times the ion species is switched, frequent switching of ion species decreases the productivity of the ion implanter.
The ion source IS may include a plasma chamber 2 that generates a plasma P inside, an extraction electrode E that extracts ion beams IB from the plasma P generated inside the plasma chamber 2 through an ion extraction port 6 of the plasma chamber 2, a second gas supply line 11 that supplies a gas as a first source for the plasma P to the plasma chamber 2 and a vaporizer S that supplies a vapor V as a second source for the plasma P, to the plasma chamber 2.
The plasma chamber 2 is surrounded by a cathode that emits electrons to ionize a gas or vapor supplied thereto, a reflecting electrode that reflects electrons emitted from the cathode back to the cathode side, and a pair of electromagnets that generate a magnetic field in a direction in which the cathode and the reflecting electrode are opposite each other, but the cathode, the reflecting electrode, and the pair of electromagnets are omitted to simplify the figures.
The extraction electrode E comprises a suppression electrode 7 for preventing electrons from flowing into the plasma chamber 2 and a grounding electrode 8 for fixing a ground potential. A DC power supply, not shown in the figures, is connected between the plasma chamber 2 and the suppression electrode 7, with the plasma chamber 2 side being positive, and a potential difference between the plasma chamber 2 and the suppression electrode 7 causes the ion beam IB with positive charge to be extracted from the plasma P through the ion extraction port 6 of the plasma chamber 2.
The vaporizer S supplies a reactive gas that chemically reacts with a solid material 4 through the first gas supply line 13 to a crucible 3 in which the solid material 4 is installed, thereby generating reaction products on the surface of the solid material 4. The solid material may include, for example, pellets, powder, blocks, and various other shapes of material. The crucible 3 is then heated by a heater 5 to vaporize the generated reaction product to generate the vapor V.
To give a specific example, in some embodiments, the solid material 4 may be an aluminum-containing material such as pure aluminum or aluminum fluoride, and the reactive gas may be a halogen gas such as chlorine gas or fluorine gas.
When a first open/close valve 14 in the first gas supply line 13 is open, the reactive gas is supplied to the crucible 3 from a first gas supply bottle 16 through the first gas supply line 13. When the reactive gas is supplied to the crucible 3, a chemical reaction occurs between the reactive gas and the solid material 4, and reaction products are formed on the surface layer of the solid material 4. For example, if the reactive gas is chlorine gas and the solid material 4 is pure aluminum, aluminum chloride is formed on the surface of the pure aluminum as a reaction product. If the reactive gas is fluorine gas and the solid material 4 is pure aluminum, aluminum fluoride is formed on the surface layer of the pure aluminum as a reaction product.
A heater 5 (e.g., a coil heater, a sheet heater, etc.) for heating the crucible 3 and a thermocouple TC for measuring the temperature of the crucible 3 are arranged around the crucible 3. When the crucible 3 is heated above a threshold temperature by the heater 5, the reaction products formed on the surface portion of the solid material 4 are vaporized. The threshold temperature may be predetermined and in some embodiments may be set experimentally or preset in the ion source IS. The vapor V of the reaction products is then supplied to the plasma chamber 2 through the vapor supply line 12. The threshold temperature is the temperature at which vaporization of the reaction products is possible and is below a melting point of the solid material 4.
Specifically, if the reaction product is aluminum chloride, the temperature for vaporizing is about 180° C., although the temperature may vary depending on a degree of vacuum in the crucible 3. If the solid material 4 is pure aluminum, the melting temperature of pure aluminum is about 660° C. Under these conditions, the threshold temperature can be any temperature between about 200° C. and about 500° C. In some embodiments, the threshold temperature may be a temperature range rather than a specific temperature. For example, in the case that the solid material 4 is pure aluminum, the threshold temperature may be in the range of 300° C. to 400° C.
As described above, a second gas supply line 11 may be provided that supplies the gas to the plasma chamber 2 through a supply path separate from the vapor. The gas may be enclosed in a second gas supply bottle 17. When a second open/close valve 15 is opened, the gas is supplied to the plasma chamber 2 through the second gas supply line 11. At this time (i.e., when the gas is supplied to the plasma chamber 2), the first open/close valve 14 is closed and the supply of a reactive gas is stopped.
The opening and closing operations of the first and second open/close valves 14, 15 and the adjustment of the output of the heater 5 may be carried out by an operator of the ion implanter or by a controller C, shown in
The horizontal axis of each graph in
After the gas supply is stopped from the second gas supply line 11, vapor is supplied from the vaporizer S. In the vapor supply method according to various embodiments, the output control of the heater 5 is different from an output control of the related art technology.
In the vaporizer S, if the supply of the reactive gas through the first gas supply line 13 is stopped, no reaction products produced by the chemical reaction with the solid material 4 will be generated. If there are no reaction products, no vapor of reaction products will be produced even if the output of the heater 5 is maintained. Therefore, if the supply of the reactive gas is controlled, the vapor supply to the plasma chamber 2 can be controlled.
When comparing a time required to adjust the temperature of crucible 3 and a time required to control the on/off of the gas supply in switching the ion species, the former is longer than the latter. According to various embodiments, a switching time of the ion species can be shortened compared to a related art configuration because the switching of ion species only requires controlling the switching of the reactive gas from the first gas supply line 13 and the gas from the second gas supply line 11.
In
If power consumption of the heater 5 and deterioration due to long-term use are to be considered, in some embodiments, the power output of the heater 5 may be kept low while the gas is supplied from the second gas supply line 11 to the plasma chamber 2, as shown in
If the gas is supplied from the second gas supply line 11 to the plasma chamber 2 for a long period of time, according to some embodiments, the power output of the heater 5 may be set to zero, and shortly before the switching of ion species is implemented, the power output of the heater 5 may be switched to a power output for vapor supply.
In
In some embodiments, the solid material 4 in
The ion source IS can be used in a variety of ion beam irradiation devices that use ion beams to process irradiated materials. Examples of ion beam irradiation devices other than ion implanters include ion beam etching devices and surface modification devices using ion beams.
It should be understood that the present disclosure is not limited to the above embodiments, but various other changes and modifications may be made therein without departing from the spirit and scope thereof as set forth in appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-122482 | Aug 2022 | JP | national |
