JP3724311B2 - Ion beam generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ion beam generating apparatus that is used for, for example, ion implantation into a semiconductor substrate and that is configured to generate a source gas by heating a liquid or solid source material at room temperature and supplying the source gas to an ion source. More specifically, the present invention relates to a means for suppressing the deposition of the source material in the gas line through which the source gas passes.
[0002]
[Prior art]
A conventional example of this type of ion beam generator is shown in FIG. The ion beam generator includes a source gas source 2 in which a source material that is liquid or solid at room temperature is stored, and the source gas source 2 is heated to a set temperature to vaporize the source material in the source gas source 4. A flow rate regulator 10 that controls the flow rate of the raw material gas 4, and a flow rate regulator 10 that supplies the raw material gas 4. An ion source 12 that ionizes the source gas 4 to generate an ion beam 14, and a valve (valve) that is provided between the source gas source 2 and the flow rate controller 10 to control (for example, open and close) the gas flow. ) 8 and a gas pipe 16 connecting the source gas source 2, the valve 8, the flow rate controller 10, and the ion source 12.
[0003]
The source material that is liquid or solid at room temperature stored in the source gas source 2 is, for example, an organic metal that is liquid or solid at room temperature (for example, trimethylindium or triethylindium).
[0004]
The ion source 12 is, for example, a Bernus type ion source as described in Japanese Patent Application Laid-Open No. 9-35648, or a known Freeman type ion source.
[0005]
A tape-shaped heater 20 is wound around the gas pipe 16. By this heater 20, the entire gas pipe 16 is heated to a substantially constant temperature T ₀ to suppress the deposition of the raw material from the raw material gas 4 in the gas pipe 16.
[0006]
[Problems to be solved by the invention]
However, in the above ion beam generator, the source gas 4 is not locally wound in the gas line of the source gas 4 (the path of the source gas 4) due to non-uniform winding of the heater 20 around the gas pipe 16 or non-uniform heat exchange with the outside air. In particular, temperature non-uniformity is likely to occur, and the raw material gas 4 is liquified or solidified in such a place, and the raw material is likely to be precipitated. In particular, in the vicinity of the inlet of the valve 8 or the flow rate regulator 10, the gas conductance deteriorates and the concentration (gas pressure) of the raw material gas 4 increases, so that precipitation is more likely to occur.
[0007]
When such precipitation occurs, the precipitate gradually grows as the operation time elapses, which may cause clogging of the gas pipe 16, the valve 8, the flow rate controller 10, and the like. As a result, it is difficult to stably supply the source gas 4 to the ion source 12, and it is difficult to stably generate the ion beam 14.
[0008]
Accordingly, the main object of the present invention is to suppress the deposition of the source material in the gas line through which the source gas passes and to stably supply the source gas to the ion source.
[0009]
[Means for Solving the Problems]
The ion beam generator of the present invention stores the gas pipe from the source gas source to the vicinity of the inlet of the valve, the source gas source, and the heater, and heats them to a first set temperature. And the gas pipe and the valve from the outlet of the first oven to the vicinity of the inlet of the flow rate regulator are housed and heated to a second set temperature higher than the first set temperature. A second oven that stores the gas pipe from the outlet of the second oven to the vicinity of the inlet of the ion source and the flow rate regulator, and has a third temperature higher than the second set temperature. And a third oven for heating to a set temperature.
[0010]
According to the above configuration, the gas line for supplying the source gas to the ion source is divided and stored in the first to third ovens that heat the entire contents to the set temperature. Therefore, the gas line temperature can be made uniform. Thereby, precipitation of the raw material in the gas line in each oven can be suppressed. This is the first action.
[0011]
Moreover, as described above, in the vicinity of the inlet of the valve or the flow rate regulator, the gas conductance deteriorates to increase the concentration of the raw material gas, and the gas concentration tends to increase more in the downstream side. Then, in accordance with such a tendency, the lower the oven, the higher the set temperature for heating and the temperature gradient, so that the deposition of the raw material can be more effectively suppressed. This is the second action.
[0012]
According to this invention, the first and second actions as described above can effectively suppress the deposition of the source material in the gas line through which the source gas passes. It can be supplied stably for a long time.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an example of an ion beam generator according to the present invention. Parts identical or corresponding to those in the conventional example shown in FIG. 2 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.
[0014]
This ion beam generator stores the gas pipe 16, the source gas source 2 and the heater 6 from the source gas source 2 to the vicinity of the inlet of the valve 8, and these are stored in a first set temperature T _1. The first oven 31 for heating to the first and the gas piping 16 and the valve 8 from the outlet of the first oven 31 to the vicinity of the inlet of the flow rate regulator 10 are stored, and these are stored in the first set temperature. A second oven 32 for heating to a _second set temperature T ₂ higher than T _{1, the} gas pipe 16 and the flow rate controller 10 from the outlet of the second oven 32 to the vicinity of the inlet of the ion source 12. And a third oven 33 for heating them to a _third set temperature T ₃ higher than the second set temperature T ₂ . That is, the ovens 31 to 33 can perform temperature adjustment independently of each other.
[0015]
Further, the ion beam generator of this example has first to third heaters 21 to 23 provided around the gas pipe 16. In addition, unlike the conventional example, each of the heaters 21 to 23 is independent of each other, more specifically, within each of the ovens 31 to 33, and the temperature can be adjusted independently of each other. . And in the ion beam generator includes a first heater 21 in the first oven 31 heats the gas pipe 16 in the oven 31 to approximately equal setting temperatures T ₁ 'and the set temperature T ₁ of the first, second The second heater 22 in the second oven 32 heats the gas pipe 16 in the oven 32 to a set temperature T ₂ ′ substantially equal to the _second set temperature T _2, and the third heater 33 in the third oven 33 the heater 23 is set the heating temperature to heat the gas pipe 16 in the oven 33 to approximately equal the set temperature T ₃ 'and the third set temperature T _3.
[0016]
Each of the heaters 21 to 23 is preferably composed of, for example, a tape-shaped heater (which is also called a ribbon heater) wound around the gas pipe 16. By doing so, the attachment of each heater and the uniform heating of the gas pipe 16 are facilitated.
[0017]
The relationship between the above set temperatures can be expressed as follows.
[0018]
[Expression 1]
T ₁ (≈T ₁ ′) <T ₂ (≈T ₂ ′) <T ₃ (≈T ₃ ′)
[0019]
According to this ion beam generator, the gas line that supplies the source gas 4 to the ion source 12 is stored separately in the first to third ovens 31 to 33 that heat the entire stored item to the set temperature. Thus, in each of the ovens 31 to 33, local temperature non-uniformity can be prevented and the gas line temperature can be made uniform. Thereby, precipitation of the raw material substance in the gas line in each oven 31-33 can be suppressed.
[0020]
In addition, as described above, in the vicinity of the inlet of the valve 8 or the flow rate regulator 10, the gas conductance deteriorates and the concentration of the raw material gas 4 increases. In this apparatus, in accordance with such a tendency, the lower the oven, the higher the set temperature for heating and the temperature gradient, so that the deposition of the raw material can be more effectively suppressed.
[0021]
In this way, it is possible to effectively suppress the deposition of the source material in the gas line through which the source gas 4 passes, so that the source gas 4 can be stably supplied to the ion source 12 for a long period of time. As a result, the ion beam 14 can be stably generated from the ion source 12 for a long period of time, and maintenance work can be reduced and the apparatus operation rate can be improved.
[0022]
The temperature difference between the set temperatures T _{1 to} T _{3 of the} ovens 31 to 33, that is, the temperature difference between T ₁ and T ₂ and the temperature difference between T ₂ and T ₃ are, for example, 5 ° C. to 10 ° C., respectively. It is preferable to set the temperature to about ° C. When the temperature difference is smaller than this, the effect of suppressing the deposition of the raw material in the vicinity of the inlets of the valve 8 and the flow rate regulator 10 is reduced. However, even if the temperature difference is larger than the above, not only does the precipitation suppression effect increase, but also wastes energy. Therefore, if the temperature difference is as described above, the effect of suppressing the precipitation of the raw material is high, and the energy utilization efficiency is also high.
[0023]
Even if the heaters 21 to 23 are not provided, it is possible to effectively suppress the deposition of the raw material in the gas line by the operation of the ovens 31 to 33. It is preferable to provide the heaters 21 to 23 as described above and set the heating temperature as described above. By doing so, it becomes possible to make the devices such as the gas pipes 16 stored in the respective ovens 31 to 33 reach the set temperatures T _{1 to} T ₃ of the respective ovens 31 to 33 more quickly.
[0024]
In addition, in an ion beam generator for production (for example, an ion implantation apparatus), in order to instantaneously switch and use the type of the source gas 4 supplied to the ion source 12, a plurality of gas lines as described above are provided, In some cases, the raw material gas 4 is kept at a certain pressure in the gas pipe 16 of each gas line. In this case, since the raw material gas 4 is always filled in the gas pipe 16, the raw material material is further precipitated. It tends to happen. When the present invention is applied to each gas line of such an apparatus, it is possible to effectively suppress the deposition of the raw material in each gas line, so that a greater effect can be exhibited.
[0025]
【The invention's effect】
As described above, according to the present invention, since the first to third ovens as described above are provided, it is possible to prevent the occurrence of local temperature nonuniformity in each oven and suppress the precipitation of the raw material. In addition, the lower the oven, the higher the set temperature for heating in line with the tendency of the gas concentration to increase near the inlet of the valve or flow controller, so that the deposition of the raw material can be more effectively suppressed. it can. As a result, the source gas can be stably supplied to the ion source for a long period of time.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an ion beam generator according to the present invention.
FIG. 2 is a diagram showing an example of a conventional ion beam generator.
[Explanation of symbols]
2 Source gas source 4 Source gas 6 Heater 8 Valve 10 Flow rate regulator 12 Ion source 14 Ion beam 16 Gas piping 21-23 Heaters 31-33 Oven

Claims (1)

A source gas source containing a source material that is liquid or solid at room temperature, a heater that heats the source gas source to vaporize the source material therein to generate a source gas, and is supplied from the source gas source A flow rate regulator that controls the flow rate of the source gas, an ion source that ionizes the source gas supplied from the flow rate controller to generate an ion beam, and the source material In an ion beam generator comprising a valve provided between a gas source and the flow rate regulator, and a gas pipe connecting the source gas source, the valve, the flow rate regulator and the ion source,
A first oven for storing the gas piping from the source gas source to the vicinity of the inlet of the valve, the source gas source and the heater and heating them to a first set temperature;
The gas pipe and the valve from the outlet of the first oven to the vicinity of the inlet of the flow rate regulator are stored, and the second is configured to heat them to a second set temperature higher than the first set temperature. An oven,
The gas pipe and the flow rate controller from the outlet of the second oven to the vicinity of the inlet of the ion source are stored, and the third is configured to heat them to a third set temperature higher than the second set temperature. An ion beam generator.

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