US-12626888-B2 - Vaporizer and ion source

Abstract

An ion source includes a vaporizer, an arc chamber, and an extraction electrode. The vaporizer includes a crucible and a heater. The crucible stores a solid material. The heater heats the crucible. The crucible has an interior space formed by a wall, an inlet connected to the wall that releases a reactive gas into the interior space, and an outlet connected to the wall that releases the reactive gas and a vapor of the reaction product generated by a reaction between the solid material and the reactive gas from the interior space. The interior space narrows toward at least one of the inlet and the outlet.

Inventors

• George Sacco
• Sami K. Hahto

Assignees

• NISSIN ION EQUIPMENT CO., LTD.

Dates

Publication Date

20260512

Application Date

20240223

Claims (14)

1. 1 . A vaporizer comprising: a crucible configured to receive a solid material; and a heater that heats the crucible, wherein the crucible includes: a wall forming an interior space of the crucible, an inlet connected to the wall that releases a reactive gas into the interior space, and an outlet connected to the wall that releases the reactive gas and a vapor of a reaction product generated by a reaction between the solid material and the reactive gas from the interior space, and wherein the interior space of the crucible narrows toward at least one of the inlet and or the outlet.
2. 2 . The vaporizer as recited in claim 1 , wherein the interior space narrows toward both the inlet and the outlet.
3. 3 . The vaporizer as recited in claim 1 , wherein the wall has a slope structure, thereby narrowing the interior space.
4. 4 . The vaporizer as claimed in claim 1 , wherein the wall has a symmetric structure.
5. 5 . The vaporizer as claimed in claim 1 , wherein the crucible is a cylindrical shape and a center axis of the crucible coincides with a line connecting the inlet and the outlet.
6. 6 . An ion source comprising: the vaporizer as recited in claim 1 , an arc chamber that generates a plasma from the vapor supplied from the vaporizer, and an extraction electrode that extracts an ion beam from the plasma.
7. 7 . A vaporizer comprising: a crucible configured to receiving a solid material, the crucible comprising an inlet for receiving a reactive gas into the crucible, an outlet through which the reactive gas and vapor are released from the crucible, and a wall that connects the inlet to the outlet; and a heater that heats the crucible, wherein: a first portion of the wall extends in parallel to a direction connecting the inlet and the outlet, a second portion of the wall connects the first portion to the inlet, a third portion of the wall connects the first portion to the outlet, and at least one of a dimension of the second portion decreases toward the inlet or a dimension of the third portion decreases toward the outlet.
8. 8 . The vaporizer as claimed in claim 7 , wherein the second portion of the wall is sloped from the first portion to the inlet.
9. 9 . The vaporizer as claimed in claim 8 , wherein the third portion of the wall is sloped from the first portion to the outlet.
10. 10 . The vaporizer as claimed in claim 7 , wherein the third portion of the wall is sloped from the first portion to the outlet.
11. 11 . The vaporizer as claimed in claim 7 , wherein the dimension of the second portion is a diameter of the second portion, and the dimension of the third portion is a diameter of the third portion.
12. 12 . The vaporizer as claimed in claim 7 , wherein the dimension of the second portion decreases toward the inlet and the dimension of the third portion decreases toward the outlet.
13. 13 . The vaporizer as claimed in claim 12 , wherein the dimension of the second portion is a diameter of the second portion, and the dimension of the third portion is a diameter of the third portion.
14. 14 . An ion source comprising: the vaporizer as recited in claim 7 , an arc chamber that generates a plasma from the vapor supplied from the vaporizer, and an extraction electrode that extracts an ion beam from the plasma.

Description

BACKGROUND 1. Field The present disclosure relates to a vaporizer, and an ion source having the vaporizer. 2. Description of Related Art Silicon carbide (SiC) devices are expected to be used in high-voltage and high-temperature applications such as electric vehicles, railways and power plants, and are featured as one of the items to realize a low-carbon society. The manufacturing process for SiC devices is similar to that of conventional silicon devices in that both use an ion implantation process. In the ion implantation process for SiC devices, nitrogen or phosphorus ions are implanted as an N-type dopant and aluminum or boron ions are implanted as a P-type dopant into a SiC wafer in the production of a PN junction. However, since there is no stable gas at room temperature for ion implantation of aluminum ions, plasma generation and ion beam extraction based on a solid material containing aluminum are performed. As a related art method, vaporizing an aluminum-containing solid material (including those in powder form) has been utilized to generate plasma containing aluminum ions. SUMMARY According to an aspect of one or more embodiments, there is provided a vaporizer comprising a crucible configured to receive a solid material; and a heater that heats the crucible. The crucible includes a wall forming an interior space of the crucible, an inlet connected to the wall that releases a reactive gas into the interior space, and an outlet connected to the wall that releases the reactive gas and a vapor of a reaction product generated by a reaction between the solid material and the reactive gas from the interior space. The interior space of the crucible narrows toward at least one of the inlet and the outlet. According to another aspect of one or more embodiments, there is provided a vaporizer comprising a crucible configured to receiving a solid material, the crucible comprising an inlet for receiving a reactive gas into the crucible, an outlet through which the reactive gas and vapor are released from the crucible, and a wall that connects the inlet to the outlet; and a heater that heats the crucible. A first portion of the wall extends in parallel to a direction connecting the inlet and the outlet, a second portion of the wall connects the first portion to the inlet, a third portion of the wall connects the first portion to the outlet, and at least one of a dimension of the second portion decreases toward the inlet and a dimension of the third portion decreases toward the outlet. According to yet another aspect of one or more embodiments, there is provided an ion source comprising the vaporizer as recited above, an arc chamber that generates a plasma from the vapor supplied from the vaporizer, and an extraction electrode that extracts an ion beam from the plasma. BRIEF DESCRIPTION OF THE DRAWINGS The above and/or other aspects will become apparent and more readily appreciated from the following description of various embodiments, taken in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic cross-sectional view of an example of an ion source, according to some embodiments; FIG. 2 illustrates an example of a first nozzle of the ion source, according to some embodiments; FIG. 3-5 illustrate an example of an insulator of the vaporizer, according to some embodiments; and FIGS. 6, 7, 9, 11-16 illustrate schematic cross-sectional views of examples of a crucible of the ion source, according to various embodiments. FIGS. 8 and 10 illustrate schematic cross-sectional views of examples of an crucible, for purposes of comparison. DETAILED DESCRIPTION As used in this specification, the phrase “at least one of A and B” includes within its scope “only A”, “only B”, and “A and B”, and the phrase “at least one of A or B” includes within its scope “only A”, “only B”, and “A and B”. As discussed above, in the ion implantation process for SiC devices, nitrogen or phosphorus ions are implanted as an N-type dopant and aluminum or boron ions are implanted as a P-type dopant into a SiC wafer in the production of a PN junction. Nitrogen gas, phosphine, phosphorus trifluoride or boron trifluoride are stable at room temperature. Therefore, nitrogen gas, phosphine, phosphorus trifluoride or boron trifluoride are used to generate plasma, and an ion beam is extracted from the generated plasma for ion implantation of nitrogen, phosphorus or boron ions to a SiC wafer. On the other hand, since there is no stable gas at room temperature for ion implantation of aluminum ions, plasma generation and ion beam extraction based on a solid material containing aluminum are performed. In the related art method of generating plasma from the aluminum-containing solid material, the aluminum-containing solid material is placed in a crucible. Vaporizing an aluminum-containing solid material (including those in powder form) has been utilized to generate plasma containing aluminum ions. In this related art method, aluminum-containing