JPH0224943A - Ion implanter - Google Patents

Abstract

PURPOSE:To suppress variation in the amount of ion beam by supporting the solid ion seed with a mesh-formed support, and heating from surroundings with the radiation heat. CONSTITUTION:The solid ion seed makes contact either dottedly or linearly with the wall of an accommodation hole at the starting time of heating, and transfer to surface contacting one by one from the contacting part, and the heat is conducted efficiently, and the amount of gas generation will increase. When power-formed solid ion seed is used, the generated residues are interposed between the wall surface and powder to hinder heat transfer, and gas generation is decreased. Accordingly the solid ion seed is supported in a mesh formed vessel 61, and the substrate 16 is heated by a rod-shaped heater 18, and the radiated heat from this substrate 16 is reflected by a heat reflex cover 28 to be returned to the substrate 16, and thus the solid ion seed cartridge 23 is effectively heated with the radiation heat, which should suppress variation in the amount of gas generation to lead to decrease of the variation in the amount of ion beam.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an ion implantation device.

(Prior Art) Generally, an ion implantation device is widely used as a device for doping impurities into, for example, semiconductor wafers, and uses gas or solid ion species as an ion source.

Among these ion implanters, those that use solid ion species heat the solid ion species,
A gas generation mechanism for gasification by sublimation or evaporation is arranged.

In a conventional ion implanter, the gas generation mechanism is configured as follows, for example. That is, as shown in FIG. 8, the gas generating mechanism 3 inserted and fixed from the outside so as to close the opening 2 of the vacuum chamber 1 includes a base body 4 formed into a rod shape from heat-resistant stainless steel, etc., and this base body. 4
A fixing plate 5 is provided at the end of the vacuum chamber 1 and fixed to the wall of the vacuum chamber 1 so as to close the opening 2, and a heater 6 is wound around the base 4. ,
An ionic species accommodation hole 7 is bored to accommodate solid ionic species.

Further, at the tip of the ionic species accommodation hole 7, a nozzle 8 is freely provided by, for example, a screw or the like, and this nozzle 8 is removed and phosphorus having a particle size of, for example, several millimeters is injected into the ionic species accommodation hole 7. It is configured so that it can be filled with solid ionic species such as arsenic and antimony.

Then, by energizing the heater 6, the solid ion species are heated to generate gas, and this gas is introduced into an ion generation chamber (not shown) through a nozzle 8, and ions are generated by, for example, applying a DC voltage. .

Note that, as mentioned above, since the heater 6 of the gas generation mechanism 3 is provided within the vacuum chamber 1, heat conduction through the air does not occur, so that the heat generated by the heater 6 is efficiently transmitted to the base 4. As such, the heater 6 is welded to the base body 4 by, for example, brazing.

(Problems to be Solved by the Invention) However, as a result of detailed research and development by the present inventors, it has been found that the conventional ion implantation apparatus described above has the following problems.

That is, when, for example, phosphorus with a particle size of several millimeters is used as the solid ion species as described above, as shown by curve G in the graph of FIG. 9, where the vertical axis is the ion beam amount and the horizontal axis is time, This means that after the ion beam amount increases rapidly within a certain startup time, it continues to gradually fluctuate (increase) over a long period of time and does not reach a constant value. This seems to be due to fluctuations (increases) in the amount of gas generated from the solid ion species, but if there is such a fluctuation in the ion beam amount,
There is a risk that the uniformity of the doping amount among the objects to be treated may be impaired.

The present invention has been made in response to such conventional circumstances, and it is an object of the present invention to provide an ion implantation device that can suppress fluctuations in the amount of ion beam and perform uniform processing compared to the prior art. It is.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides an ion implantation device that heats solid ion species in a vacuum container to generate gas, and ionizes the gas to generate an ion beam. , the solid ionic species is supported by a mesh-like support, and the solid ionic species is heated mainly by radiant heat from the surroundings.

(Function) As shown in the graph of Figure 9 above, in conventional ion implanters, the ion beam amount increases rapidly within a certain startup time, and then gradually fluctuates (increases) over a long period of time. Continue. This is presumed to be because the amount of gas generated from the solid ion species fluctuates (increases) due to the following phenomenon.

That is, the solid ion species accommodated in the ion species accommodation hole of the gas generation mechanism are heated in point or line contact with the wall surface of the ion species accommodation hole at the start of heating.

However, since the solid ionic species is consumed from this contact area, as time passes, the contact state between the solid ionic species and the wall surface in the ionic species storage hole gradually becomes surface contact.
Heat is efficiently transferred from the wall surface to the solid ionic species, increasing the amount of gas generated.

In addition, in order to prevent the occurrence of such a phenomenon, when solid ion species pulverized into powder are used, the ion beam amount will gradually decrease as shown by curve H in the graph of Figure 9. It was also revealed. This is presumed to be because, as time passes, residue generated from the solid ionic species becomes interposed between the powdered solid ionic species and the wall surface, inhibiting heat transfer.

Therefore, in the ion implantation apparatus of the present invention, the solid ion species are supported by a mesh-like support, for example, housed in a container whose wall surface is configured in a mesh shape, and the contact area with the high-temperature part is reduced. By configuring the ion beam to be heated mainly by radiant heat from the surroundings, fluctuations in the amount of gas generated are suppressed, thereby suppressing fluctuations in the amount of ion beam.

(Example) Hereinafter, an example of the ion implantation apparatus of the present invention will be described with reference to the drawings.

An opening 12 is formed in the vacuum chamber 11, and a gas generating mechanism 13 is inserted and fixed from the outside so as to close this opening 12.

That is, at the end of the gas generation mechanism 13, as shown in FIG.
4, and this fixing plate 14 is provided with an O-ring 1 that is in contact with the vacuum chamber 11 to ensure airtightness.
5 is placed.

By fixing this fixing plate 14 to the vacuum chamber 11 with, for example, screws, the opening 12 is hermetically closed and the gas generating mechanism 13 is provided to protrude into the vacuum chamber 11.

Further, a rod-shaped base body 16 made of a material such as heat-resistant stainless steel is fixed at one end to the fixing plate 14, and as shown in FIG. Four heater insertion holes 1 along the longitudinal direction from the side
7 are bored, and rod-shaped heaters 18 are inserted into these heater insertion holes 17, respectively. Note that the front half of these heaters 18 is the heat generating part 18 from the tip.
a, and the rear half is a support portion (non-heat generating portion) 18b. Further, a temperature detector insertion hole 19 and three cooling gas introduction holes 20 are bored between these heater insertion holes [7]. As shown in FIGS. 3 and 4, a thermocouple 21, for example, is inserted as a temperature detector into the temperature detector insertion hole 19, and the cooling gas introduction hole 20 is inserted into the temperature sensor insertion hole 19.
There is a pipe 22 for delivering a cooling gas such as air.
has been inserted. Note that the thermal lightning pair 21 is used to detect the temperature inside the base body 16 and adjust the amount of electricity supplied to the heater 16 to control the temperature, and the piping 22 is used for rapid cooling during maintenance, for example. It is for.

On the other hand, a cartridge accommodating hole 24 for accommodating the solid ion species cartridge 23 is bored on the tip side of the base body 16 in accordance with the outer shape of the solid ion species cartridge 23. Moreover, two L-shaped notches 25, for example, are provided at the tip of the base body 16 as a mechanism for locking the solid ion species cartridge 23.

As shown in FIG. 5, the solid ion species cartridge 23 is made of a material such as stainless steel and has a substantially cylindrical shape, and a cylindrical ion species storage chamber 60 is bored in the interior along the longitudinal direction. It is set up. A mesh container 61 is inserted into the ionic species storage chamber 60 to accommodate solid ionic species such as phosphorus having a particle size of, for example, several millimeters.

That is, the mesh container 61 is made of a material such as stainless steel and is formed into a cylindrical shape with a bottom, and is supported by a ring-shaped support member 62. . The mesoche diameter is selected depending on the size of the solid ionic species. Further, this support member 62 is provided with a detachable disk-shaped lid 63, and the interior can be filled with solid ionic species by removing this lid 63. Note that the outer diameter of the support member 62 is slightly larger than that of the mesh portion, and the mesh container 61 is connected to the ionic species storage chamber 60.
When placed inside the mesh part and ionic species storage chamber 6
A slight gap is created between the inner wall of the ion species storage chamber 60 and the mesh portion is configured so as not to directly contact the inner wall of the ion species storage chamber 60.

At the opening of the ionic species storage chamber 60, a lid 65 with a nozzle 64 protruding from its center is removably attached, for example, by screws, and a heat transfer rod is provided on the opposite side. 66 are provided.

Further, a stepped portion 67 is provided on the outer side of the ion species storage chamber 60 so that the opening side has a larger diameter, and this stepped portion 67 is provided with an L-shaped claw 68.

Therefore, the cartridge accommodating hole 24 provided in the base body 16 has a small diameter and extends to the area between the heaters 18 , and the heat transfer rod 66 of the solid ion species cartridge 23 is inserted therein. It is configured to efficiently heat solid ionic species.

Then, the solid ion species cartridge 23 is inserted into the cartridge accommodation hole 24 of the base 16, and the claw 68 of the ion species cartridge 23 is inserted into the L-shaped notch 25 of the base 16.
A set nut 26 and, for example, four plate springs 27 are arranged at the tip of the ion species cartridge 23, and a cylindrical heat reflecting cover 28 is placed on the top of the ion species cartridge 23, as shown in FIG. The L-shaped notch 29 provided on the cover 28 and the protrusion 30 provided on the base 16 are engaged and fixed. That is, the solid ion species cartridge 23 is fixed in a pressed state against the base 16 by the disc spring 27, so that heat from the base 16 is efficiently transmitted to the solid ion species cartridge 23. Also,
The heat reflecting cover 28 is for reflecting the heat radiated from the base 16 and returning it to the base 16 to improve thermal efficiency.

In the ion implantation apparatus of this embodiment having the above configuration, the mesh container 61 is filled with solid ion species, such as arsenic with a particle size of several millimeters, for example, on the order of several tens of grams.
The ionic species storage chamber 6 of the solid ionic species cartridge 23
0, the gas generating mechanism 13 is assembled as described above, and placed in the vacuum chamber 11. Then, by applying electricity to the heater 18, the solid ion species are heated and gas is generated. This gas flows from the ion species storage chamber 60 through the nozzle 64 to an ion generation chamber (not shown) where ions are generated by applying a DC voltage, for example, and is ionized. These ions are electrically extracted from the ion generation chamber, converted into a desired electron beam by a mass spectrometer magnet, accelerator tube, electrostatic lens, etc., and scanned by a deflection electrode, etc., and then scanned and irradiated onto, for example, a semiconductor wafer.

At this time, the solid ion species are provided in the mesh container 61 and are kept in a state of non-contact with the inner wall of the ion species storage chamber 60. Therefore, although there is a slight amount of heat conduction through the mesh container 61, heating is mainly caused by radiant heat from the inner wall of the ion species storage chamber 60. Also,
The residue generated by consumption of the solid ionic species falls from the mesh container 61 into the ionic species storage chamber 60 . Therefore, the heating state becomes substantially constant, and fluctuations in the amount of gas generated over time can be suppressed.

The curve (2) shown in the graph of FIG. 7, in which the vertical axis is the ion beam amount and the horizontal axis is time, shows the change in the ion beam amount measured using the ion implantation apparatus of this embodiment. In addition,
As the solid ionic species, arsenic with a particle size of 1 to 2 mm was used.

As shown in this graph, the ion implantation apparatus of this embodiment can suppress fluctuations in the amount of ion beam compared to the conventional ion implantation apparatus, and can perform uniform processing.

In the above embodiment, the heater 18 is built into the base 16, and maintenance of the heater 18 is carried out in the vacuum chamber 11.
Although the ion implantation device configured to be able to be accessed from the outside has been described, the present invention is not limited to such an embodiment. For example, as in the conventional ion implantation device shown in FIG. The present invention can be similarly applied to an ion implantation device or the like in which a coil of 6 is wound.

[Effects of the Invention] As described above, according to the ion implantation apparatus of the present invention, fluctuations in the amount of ion beam can be suppressed compared to the conventional method.
Uniform processing can be performed.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway cross-sectional view showing the main structure of an ion implantation apparatus according to an embodiment of the present invention, FIG. 2 is a view taken along arrow A in FIG. 1, and FIG. B sectional view, Figure 4 is C in Figure 2
-C sectional view, Fig. 5 is an exploded view of the solid ion species cartridge shown in Fig. 1, Fig. 6 is a side view of Fig. 1, and Fig. 7 is the ion beam amount time of the ion implanter of the example. FIG. 8 is a cross-sectional view showing the main structure of a conventional ion implantation apparatus, and FIG. 9 is a graph showing temporal changes in the ion beam amount of the conventional ion implantation apparatus. 11... Vacuum chamber, 13... Gas generation mechanism, 18... Heater, 23...
Solid ion species cartridge, 60...Ion species storage chamber, 61...Mesh container.

Claims (1)

[Claims] (1) In an ion implantation device that heats solid ion species in a vacuum container to generate gas and ionizes this gas to generate an ion beam, the solid ion species are supported by a mesh-like support and the An ion implantation device characterized by being configured to heat solid ion species mainly by radiant heat from the surroundings.