JPH0411975B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an ion source with an evaporation furnace that vaporizes and ionizes solids or liquids, and in particular an ion source suitable for ion implantation equipment used in semiconductor manufacturing processes. Regarding ion sources.

[Background of the invention]

In high-current ion implantation equipment for implanting 10mA-class high-current ion beams into semiconductor substrates, when a filament is used as an ion source, there is a problem in that the filament is subject to rapid wear. Instead of ionization using thermionic electrons, an ion source is used that uses plasma discharge using a high-frequency electric field of microwaves.

FIG. 4 shows a schematic cross-sectional view of a conventional microwave discharge type ion source.

Microwaves 13 generated by the magnetron 8 are guided to the high voltage accelerating electrode 10 through the choke flange 14 and reach the ionization box 2 .

A magnetic field is applied to the ionization box 2 by an excitation coil 12, and a source gas is supplied from a gas introduction pipe 9. As a result, inside the ionization box 2
A plasma is ignited, thereby ionizing the source gas.

Furthermore, the ion beam 7 is extracted by the extraction electrode 15 to which an extraction voltage close to the ground potential is applied, and is used, for example, for ion implantation.

In this case, as is well known, some ion species may be solid (or liquid) samples at room temperature (for example, Al+, Ga+, P+, As+, Sb+, etc.).
is sometimes used.

In order to ionize these solid or liquid samples, in a conventional ion source as shown in FIG. The obtained vaporized gas was introduced into the ionization box 2 through the second gas introduction pipe 11 and ionized.

Further, FIG. 5 is a sectional view of a main part of a conventional filament heating type ion source. In this figure, the same reference numerals as in FIG. 4 represent the same or equivalent parts.

An evaporation furnace 1 configured to be loaded with a solid or liquid sample 3 is heated by a heater 4 disposed around the evaporation furnace 1 . The heating temperature is monitored by a thermometer 18 such as a thermocouple, and is controlled and maintained at a predetermined value.

Once the solid or liquid sample 3 has evaporated, its vaporized gas is led into the ionization box 2 through the gas introduction pipe 11. A filament 19 is stretched inside the ionization box 2. When the filament 9 is heated by applying electricity, thermoelectrons 20 are emitted into the ionization box 2, which collide with the vaporized gas to generate ions.

Although not shown in FIG. 5 for the sake of simplicity, a magnetic field is applied to the ionization box 2 from the outside, giving rotational force to the thermionic electrons 20 and reducing the probability of collision with vaporized gas. I'm trying to raise it.

The ions generated as described above are extracted by an extraction electrode (not shown), and the ion beam 7
becomes.

As mentioned above, conventional ion sources, including microwave discharge types, have a configuration in which only one evaporation furnace is provided. The problems in this case are as follows.

Since samples of different ion species (eg, As+, P+) cannot be loaded simultaneously, different ions cannot be generated successively.

If different ionic species are required for this purpose,
After generating ions of one solid or liquid sample, wait for the evaporation furnace and ion source to cool down, break the vacuum, insert a sample of another ion species, pull the vacuum again, and then heat up the evaporation furnace. However, it is necessary to pull out the beam. During this time, usually about 2
It takes several hours of equipment downtime.

This not only reduces work productivity, but also
The availability of the ion source also decreases.

In addition, even if the solid or liquid sample in the evaporation furnace runs out before the desired amount of ion implantation is completed, the sample must be reloaded by performing the same operation as above, and the same procedure can be performed. This forces a decline in work efficiency and equipment availability.

[Purpose of the invention]

An object of the present invention is to provide an ion source with an evaporation furnace that is suitable for implanting a high-voltage, large-current ion beam and can improve work efficiency and device availability.

[Summary of the invention]

The present invention is characterized by an ionization box, a plurality of evaporation furnaces each having a heater for heating and evaporating a solid or liquid sample, and a plurality of evaporation furnaces each having an ionization box and a heater for heating and evaporating a solid or liquid sample, and a plurality of evaporation furnaces each having an ionization box and a plurality of evaporation furnaces each having a heater to heat and evaporate a solid or liquid sample. means for communicating each of the evaporation furnaces with the ionization chamber; means for ionizing the vapor guided to the ionization chamber; means for drawing out ions generated by the ionization from the ionization chamber; and a power source for the heater; The present invention further includes means for selectively switching the heater with respect to the power source.

[Embodiments of the invention]

FIG. 1 shows a sectional view of the main structure of an embodiment in which the present invention is applied to a microwave discharge type ion source. Note that the same reference numerals as in FIG. 4 represent the same or equivalent parts.

As is clear from the figure, in the center of the ion source there is a waveguide section made of an insulator 16 that propagates microwaves, so the plurality of evaporation furnaces 1A, 1B, etc. according to the present invention are Installed around the waveguide section. The structures of these evaporation furnaces 1A and 1B may be exactly the same.

A plan view of the flange portion 17 of the ion source in FIG. 1 (a plan view of the flange portion 17 viewed from the left side in FIG. 1) is shown in FIG. In this figure, 17 is a flange portion of the ion source, 22 is a microwave waveguide opening, and 23, 24, 25, and 26 are a plurality of (in the illustrated example, 4) provided around the waveguide opening 22. ) solid or liquid evaporation furnaces 1A, 1B
It is an opening for mounting...

Ion implantation equipment used in conventional semiconductor manufacturing often uses arsenic and phosphorus as solid samples. The reason is that AsH ₃ as a gas sample
This is because PH3 and _PH3 are harmful gases, and solid samples are used for safety reasons.

In such a case, as in the present invention, a plurality of evaporation furnaces are installed, and for example, the evaporation furnace installation openings 23 and 25 shown in FIG. 2 are used for phosphorus, and the remaining two evaporation furnace installation openings 24 , 26 are set for arsenic, even if one of the evaporation furnaces becomes empty, the same type of ion implantation can be continued by raising the temperature of the other evaporation furnace.

In addition, if two different types of samples are loaded into each evaporation furnace, continuous operation is possible even if, for example, arsenic ions are to be implanted after phosphorous ions have been implanted, production efficiency and ion implantation equipment efficiency can be improved. The operating rate can be significantly improved.

This invention can also be easily applied to filament heated ion sources. Its outline is shown in a sectional view in FIG.

In this figure, the same reference numerals as in FIGS. 1 and 5 represent the same or equivalent parts.

The ionization box 2 is supported at a predetermined position within a cylindrical insulator 21 by an ionization box support 18 . The ionization box support 18 is fixed to the ion source flange 17, and the ion source flange 17 is hermetically joined to the end of the insulator 21.

A gas introduction pipe 9 is provided inside the ionization box support 18 so as to extend outward from the ionization box 2 through the ion source flange 17 .

A plurality of evaporation furnaces 1A, 1B, .

Further, each of the evaporation furnaces 1A, 1B, . . . is provided with a heating heater 4A, 4B, . . . and connected to a power source.

FIG. 6 shows an embodiment of an internal magnetic path type microwave discharge type ion source having two evaporation furnaces.

The numbers in the figure are the same as those in FIG. 1, and the same symbols indicate the same parts, but the excitation coil 12 is characterized in that it is attached around the ionization box 2 to which an accelerating voltage is applied. The flange 17, accelerating electrode 10, coil bobbin 29, and magnetic pole pieces 28A and 28B are made of magnetic material and serve to guide a magnetic field to the ionization box 2.
By installing the excitation coil near the ionization box in this way, there is no discharge between the flange 17 to which the accelerating voltage is applied and the excitation coil, making the entire ion source more compact compared to the case shown in Figure 1. There are some advantages.

Heaters 4A and 4B are wound around the evaporation furnaces 1A and 1B and the introduction parts 11A and 11B to heat them.

Switching of the heater of the evaporation furnace to the power source 30 is carried out by switching contacts A and B of the changeover switch 27.

As is clear from the figure, the chambers in which the samples 3A and 3B exist are in communication with each other, and are commonly evacuated by one vacuum pump. The sample mounted in advance is tested only by switching the heaters 4A and 4B. Therefore, there is no need to evacuate the sample again for sample exchange, and the heaters 4A and 4B are simply
Since this is done by switching, efficiency is improved.

Although selective switching of the heater power source for each evaporation furnace is omitted in FIGS. 1 to 3, it is performed in the same manner as in FIG. 6.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, an ion source with an evaporation furnace suitable for high-current ion beam implantation is provided. In addition, there is no need for special adjustments for ion beam extraction associated with switching use of the evaporation furnace, the evaporation furnace can be switched and used with a simple structure, and the evaporation furnace can be rotated for the switching use. Since there is no need to perform mechanical driving such as the above, it is expected that there will be no practical problem in switching use of the evaporation furnace in high temperature conditions, which is a significant practical effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main structure of a first embodiment in which the present invention is applied to a microwave discharge type ion source, FIG. 2 is a plan view of the flange portion of FIG. 1, and FIG. 3 is a filament of the present invention. The second method applied to a heated ion source
4 is a cross-sectional view showing the structure of a conventional microwave discharge type ion source; FIG. 5 is a schematic cross-sectional view of a conventional filament heating type ion source;
FIG. 6 is a sectional view of an ion source with an evaporation furnace showing an embodiment of the present invention. 1, 1A, 1B...Evaporation furnace, 2...Ionization box, 3
... solid (or liquid) sample, 4 ... heater, 7 ... ion beam, 8 ... magnetron, 9, 11 ... gas introduction pipe, 10 ... acceleration electrode, 15 ... extraction electrode,
17...Flange part, 18...Ionization box support, 22
...Microwave waveguide opening, 23-26...Opening for attaching evaporation furnace.

Claims (1)

[Scope of Claims] 1. A plurality of evaporation furnaces each having an ionization box and a heater for heating and evaporating a solid or liquid sample, and a plurality of evaporation furnaces each having an ionization box and a heater for heating and evaporating a solid or liquid sample, and a plurality of evaporation furnaces each having an ionization box and a heater for heating and vaporizing a solid or liquid sample, and a plurality of evaporation furnaces each having an ionization box and a heater for heating and vaporizing a solid or liquid sample, and a plurality of evaporation furnaces each having an ionization box and a heater for heating and evaporating a solid or liquid sample. means for communicating each of the evaporation furnaces with the ionization chamber, means for ionizing the vapor introduced into the ionization chamber, means for drawing out ions generated by the ionization from the ionization chamber, and a power source for the heater. An ion source with an evaporation furnace, comprising means for selectively turning off the heater with respect to the power source. 2. The ion source with an evaporation furnace according to claim 1, wherein the plurality of evaporation furnaces are arranged around an extension line of the beam axis of the extracted ions. 3. The ion source with an evaporation furnace according to claim 1, wherein the plurality of evaporation furnaces are arranged approximately symmetrically around an extension line of the beam axis of the extracted ions. 4. Claims 1 to 3, wherein the ionization means is of a microwave discharge type.
The ion source with an evaporation furnace according to any of the above. 5. The ion source with an evaporation furnace according to any one of claims 1 to 3, wherein the ionization means is of the thermionic impact type.