JPH0612996A - Method and device for processing ion beam - Google Patents

Abstract

PURPOSE:To provide an ion beam processing method whereby a proper discharge start can be performed. CONSTITUTION:A discharge start condition in accordance with a kind of gas to be introduced into an ionizing chamber 1 is left as prestored in a memory unit 24, to read the discharge start condition, stored in the memory unit 24, in response to assigning the kind of gas through an input/output device 25, and under this condition, the assigned gas is introduced to the ionizing chamber 1, to start a discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam processing method and apparatus, and more particularly to an ion beam processing method and apparatus for generating an ion beam based on gas discharge and treating a sample with the generated ion beam.

[0002]

2. Description of the Related Art An ion beam generator of the type that generates an ion beam based on gas discharge has a long filament life and is suitable for cleanliness. Therefore, an ion implanter and an etching device are required. It is widely used in various semiconductor manufacturing equipment.

An ion generator of this kind is one in which an electric field and a magnetic field are formed in an ionization chamber, a gas is caused to flow in the ionization chamber in that state to generate plasma by discharge, and an ion beam is extracted from this plasma. When initiating a discharge, the electric field strength, magnetic field strength and gas flow rate are generally set manually. However, since these values differ depending on the ion species, and hence the type of gas, and their values are not always clear, they often result in being set excessively.

[0004]

However, if these values are set excessively, the following problems will occur.

(1) As the sample processing condition after the start of discharge, the plasma density is excessive and the plasma becomes unstable. Therefore, it is necessary to correct the excessive set value to a value suitable for the sample processing. Is.

(2) There is a problem that the inside of the device is contaminated due to an excessive gas flow rate and the device is destroyed due to an abnormal discharge, which reduces the reliability of the entire device.

An object of the present invention is to provide an ion beam processing method and apparatus suitable for proper discharge initiation.

[0008]

According to the present invention, the discharge start condition is determined in advance according to the type of gas to be introduced into the ionization chamber, and is designated in response to the designation of the gas type. The specified gas is introduced into the ionization chamber under a discharge starting condition that is predetermined according to the kind of the gas to start the discharge.

[0009]

According to this, since it is possible to set the minimum necessary discharge start condition according to the type of gas, it is possible to prevent excessive discharge and to start discharge appropriately. .

[0010]

EXAMPLE To explain the ion implanter shown in FIG. 6, an ion beam emitted from an ion source 11 is mass-separated by a magnetic field 13, and an ion beam of a specific ion species obtained thereby is slit. Pass 14
It is driven into a sample 16 which is a semiconductor wafer placed in the driving chamber 15.

The details of the ion source 11 will be described with reference to FIG. 1. The microwave 3 generated by the microwave generator 20 passes through the inside of the waveguide 4 and through the dielectric vacuum seal 5 into the ionization chamber 1. Be guided. As a result, a microwave electric field is formed in the ionization chamber 1. The solenoid coil device 6 generates a magnetic field in the ionization chamber 1 so as to be orthogonal to the microwave electric field. When gas is introduced into the ionization chamber 1 in this state, microwave discharge occurs in the gas to generate plasma, and an ion beam is extracted from the plasma.

The gas source 21 stores a plurality of gases to be used, such as arsine gas, argon gas, nitrogen gas, boron trifluoride, phosphine and the like. A gas selected from these gases is introduced into the ionization chamber 1 via the mass flow controller 2, the storage pipe 22, and the stop valve 7. The amount of gas accumulated in the accumulation pipe 22 is determined by closing the stop valve 7 and turning the mass flow meter 2
It is determined by the time until the stop valve 7 is opened after flowing the gas to the storage pipe 22 through the mass flow meter 2 in the state where the flow rate is regulated by.

The selection of the type of gas, the opening and closing of the mass flow controller 2 and the stop valve 7, and the selection and setting of the microwave power, that is, the strength of the microwave electric field and the magnetic field are performed by the drive and / or control device 26 based on the command of the computer 23. Done by Processing conditions, discharge start conditions, and the like are stored in the storage device 24 of the computer 23 in advance.

FIG. 2 shows that, when the magnetic field strength B is 0.08 T and the microwave power is 200 W, it is necessary to start the discharge with respect to the gas flow rate (CC / M) that should be set in the normal processing step. The relationship of the gas amount (accumulated amount) (CC) is shown for each gas type. The triangular curve is the hydrogen-containing arsine gas curve, the circular curve is the argon gas curve, and the square curve is the nitrogen gas curve. From this figure, if the type and flow rate of the gas are determined, the optimum gas accumulation amount required for starting the discharge can be known.

FIG. 3 is a graph showing the nitrogen gas flow rate (CC / M) that should be set in a normal treatment process when the magnetic field strength B is 0.08 T and the microwave power is 200 W. The relationship of gas accumulation time (S) is shown. In this figure, the upper side of the curve is the discharge area and the lower side is the non-discharge area. Once the nitrogen gas flow rate is determined, it is appropriate to prevent the excessive plasma generation by selecting the value of the curve slip in the discharge region as the gas accumulation time.

FIG. 4 shows the relationship between the microwave power (W) and the gas accumulation time required to start the discharge when the magnetic field strength is 0.08 T and the nitrogen gas flow rate is 2.0 CC / M. The upper side of the curve is the discharge area, and the lower side is the non-discharge area. Once the microwave power has been determined, it is important to prevent excessive plasma generation by selecting a gas accumulation time that is close to the curve within the discharge region.

FIG. 5 shows the magnetic field strength (T) when the microwave power is 300 W and the nitrogen gas flow rate is 3 CC / M.
The relationship of the gas accumulation time (S) required to start the discharge with respect to is shown. Lowering the power translates the curve upwards.
When the flow rate of nitrogen gas is 2 CC / M, the curve is translated upward by a factor of 1.5.

The storage device 24 of the computer 23 stores in advance the kind of gas (and therefore the ion species) required for sample processing, the gas flow rate, the microwave power, the strength of the microwave electric field and the strength of the magnetic field. Has been done. Further, a gas amount table for each type of gas required for starting discharge is stored. This table may be the gas amount for each magnetic field strength and electric field strength.

To explain the operation, the conditions for sample processing from the input / output device 25 are gas type (ion species), gas flow rate, microwave power, microwave electric field strength,
The strength of the magnetic field is keyed in (Fig. 7A). By this key-in, gas was selected and corresponding to it,
The optimum gas amount for starting discharge is read from the storage device 24 (FIG. 7B). Based on this, the computer 23 calculates the optimum storage time for starting discharge (FIG. 7C). The drive and / or control device 26 controls the opening and closing of the stop valve 7 and the mass flow controller 2 according to the command of the computer 23 so that the gas is introduced into the storage tube 22 for the calculated time and the optimal amount for starting the discharge is stored. Yes (Fig. 7
D). The computer 23 opens the stop valve 7 after the accumulation time, whereby the accumulated gas is introduced into the ionization chamber 1 (FIG. 7E) and discharge is started (FIG. 7F). After the start of the discharge, the steady state is reached, and the gas of the flow rate set by the key-in is continuously introduced into the ionization chamber 1,
Sample processing is performed (Fig. 7G). FIG. 8 shows another embodiment according to the present invention. The gas introduced into the ionization chamber 1 is controlled by the mass flow controller 2.
A waveguide 4 and a vacuum seal plate 5 are provided to form a microwave electric field in the ionization chamber 1. Reference numeral 6 is a solenoid coil 6 for forming a magnetic field. Two gas pipes 8 and 9 that are introduced into the ionization chamber 1 are used as a means for instantaneously increasing the gas pressure in the ionization chamber 1. The gas pressure required for ignition, that is, for starting discharge is short when the valve 7 on the high-pressure gas side of the pipe 9 is short. It is realized by opening only time. After ignition, the valve 7 of the pipe 9 is closed and the mass flow controller 2 of the pipe 8 controls the gas flow rate that meets the sample processing conditions.

[0020]

According to the present invention, there is provided an ion beam processing method and apparatus suitable for proper discharge initiation.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a part of a main part of an ion beam processing apparatus according to an embodiment of the present invention.

FIG. 2 is data showing a relationship between a gas flow rate and a gas amount for facilitating understanding of the present invention.

FIG. 3 is a diagram showing a relationship between a nitrogen gas flow rate and a gas accumulation time in order to facilitate understanding of the present invention.

FIG. 4 is a diagram showing the relationship between the microwave power and the amount of accumulated gas for facilitating the understanding of the present invention.

FIG. 5 is a graph showing the relationship between the amount of accumulated gas and the strength of a magnetic field to help understanding of the present invention.

FIG. 6 is a conceptual diagram of an ion beam processing apparatus showing an embodiment according to the present invention.

FIG. 7 is a flowchart for explaining the operation of the present invention.

FIG. 8 is a sectional view of a main part of an ion beam processing apparatus showing another embodiment according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ionization chamber, 2 ... Mass flow controller, 4 ... Waveguide, 5 ... Dielectric vacuum seal, 6 ... Solenoid coil device, 7 ... Stop valve, 8, 9 ... Pipe, 13 ... Mass separator (magnetic field), 16 ... sample, 21 ... gas source, 22 ... storage tube, 23 ... computer, 24 ... storage device, 25 ... input / output device, 26 ... drive and / or control device.

Claims (19)

[Claims] 1. An ion beam processing apparatus for introducing a gas into an ionization chamber to generate plasma of the gas by discharging, extracting an ion beam from the generated plasma, and treating a sample with the extracted ion beam. And a means for pre-storing discharge start conditions according to the type of gas to be introduced into the ionization chamber, and a means for designating the type of gas to be introduced into the ionization chamber. In response to the above, the discharge start condition stored corresponding to the designated gas type is read from the storage means, and the discharge is started under the read discharge start condition. Characteristic ion beam processing equipment. 2. An ion beam generating means and a means for treating a sample with the generated ion beam are provided, wherein the ion beam generating means includes an ionization chamber and a type of gas to be introduced into the ionization chamber. Means for pre-storing discharge start conditions corresponding thereto, means for designating the type of gas to be introduced into the ionization chamber, and stored in response to the designation corresponding to the designated gas type. The discharge starting condition being present is read from the storage means, discharge is started in the ionization chamber under the read discharge starting condition, plasma of the designated gas is generated, and the plasma is generated from the generated plasma. An ion beam processing apparatus comprising: means for extracting an ion beam. 3. The ion beam processing apparatus according to claim 1, further comprising means for forming an electric field and a magnetic field in the ionization chamber. 4. The ion beam processing apparatus according to claim 3, wherein the discharge starting condition is determined by the strength of the electric field, the strength of the magnetic field, and the amount of the gas. 5. The ionization chamber is provided with a means for accumulating a gas to be introduced into the ionization chamber, and a means for controlling an accumulation amount of the gas in the accumulation means. The ion beam processing apparatus according to claim 4, wherein the ion beam processing apparatus is introduced into the ion beam processing apparatus. 6. The ion beam processing apparatus according to claim 5, wherein the storage means includes a first valve, a second valve for defining a flow rate, and a storage tube interposed between the valves. 7. The accumulated amount control means supplies the accumulated amount to the accumulation pipe through the second valve in a state where the first valve is closed and the flow rate is regulated by the second valve. 7. The ion beam processing apparatus according to claim 6, wherein the ion beam processing apparatus is configured to be determined by the time until the first valve is opened after flowing the gas. 8. An ion beam generator for introducing a gas into an ionization chamber to generate plasma of the gas by electric discharge and extracting an ion beam from the generated plasma, the gas being introduced into the ionization chamber. Means for pre-storing the discharge start condition according to the type of, and means for designating the type of gas to be introduced into the ionization chamber, in response to the designation, to the designated gas type An ion beam generator characterized in that the discharge start condition stored correspondingly is read from the storage means and the discharge is started under the read discharge start condition. 9. An ionization chamber, means for pre-storing discharge start conditions corresponding to the type of gas to be introduced into the ionization chamber, and means for specifying the type of gas to be introduced into the ionization chamber. And in response to the designation, the discharge start condition stored corresponding to the designated gas type is read from the storage means, and the discharge is performed in the ionization chamber under the read discharge start condition. An ion beam generator including means for starting to generate plasma of the specified gas and extracting an ion beam from the generated plasma. 10. The ion beam generator according to claim 8 or 9, further comprising means for forming an electric field and a magnetic field in the ionization chamber. 11. The ion beam generator according to claim 10, wherein the discharge starting condition is determined by the strength of the electric field, the strength of the magnetic field, and the amount of the gas. 12. The ionization chamber, comprising means for accumulating gas to be introduced into the ionization chamber, and means for controlling the amount of gas accumulated in the accumulation means. It is introduced into 1.
1. The ion beam generator described in 1. 13. The ion beam generator according to claim 12, wherein said storage means includes a first valve, a second valve defining a flow rate, and a storage tube interposed between these valves. 14. The accumulated amount control means supplies the accumulated amount to the accumulation pipe through the second valve in a state in which the first valve is closed and the flow rate is regulated by the second valve. 14. The ion beam generator according to claim 13, wherein the ion beam generator is configured to be determined by the time until the first valve is opened after flowing the gas. 15. A gas is introduced into the ionization chamber, plasma of the gas is generated in the ionization chamber by discharge in the presence of an electric field and a magnetic field, an ion beam is extracted from the plasma, and the sample is extracted by the extracted ion beam. An ion beam treatment method for treating a gas, wherein a gas amount suitable for starting the discharge is determined in advance for each treatment condition of the sample determined by the type and flow rate of the gas and the strengths of the electric field and the magnetic field. In response to the designation of the processing conditions, the designated gas is introduced into the ionization chamber by a predetermined amount of gas that is predetermined corresponding to the designated processing conditions and is suitable for starting the discharge. The ion beam treatment method, wherein the discharge is started under the treatment condition. 16. A gas is introduced into an ionization chamber, plasma of the gas is generated in the ionization chamber by electric discharge in the presence of an electric field and a magnetic field, an ion beam is extracted from the plasma, and the sample is extracted by the extracted ion beam. And a gas amount suitable for starting the discharge for each processing condition of the sample determined by the kind and flow rate of the gas and the strengths of the electric field and the magnetic field. Incidentally, in response to the designation of the processing condition, a gas amount suitable for starting the discharge stored corresponding to the designated processing condition is read from the storage device, and the read gas is read. An ion beam processing method, characterized in that a specified amount of gas is introduced into the ionization chamber and the discharge is started under the specified processing condition. 17. A gas is introduced into the ionization chamber, plasma of the gas is generated in the ionization chamber by electric discharge in the presence of an electric field and a magnetic field, an ion beam is extracted from the plasma, and the sample is extracted by the extracted ion beam. And a gas amount suitable for starting the discharge for each processing condition of the sample determined by the kind and flow rate of the gas and the strengths of the electric field and the magnetic field. Incidentally, in response to the designation of the processing condition, a gas amount suitable for starting the discharge stored corresponding to the designated processing condition is read from the storage device, and the read gas is read. The specified gas is accumulated in the accumulator for the accumulation time obtained by dividing the amount by the specified gas flow rate, and the accumulated gas is introduced into the ionization chamber. Ion beam processing method characterized by initiating the discharge in the designated processing conditions. 18. A means for generating an ion beam based on an electric discharge, and a means for treating a sample with the generated ion beam, wherein the ion beam generating means comprises an ionization chamber,
Means for forming an electric field and a magnetic field in the ionization chamber,
Means for introducing a gas into the ionization chamber, and a gas amount suitable for starting the discharge is stored in advance for each processing condition of the sample determined by the type and flow rate of the gas and the strength of the electric field and the magnetic field. Means for designating the processing condition, and in response to the designation, a gas amount suitable for starting the discharge, which is stored in advance in correspondence with the designated processing condition, is read from the storage means. An ion beam processing apparatus comprising: a specified gas in an amount corresponding to the read gas amount, which is introduced from the gas introduction unit into the ionization chamber to start the discharge under the specified processing condition. 19. A means for generating an ion beam based on an electric discharge, and a means for treating a sample with the generated ion beam, said ion beam generating means comprising an ionization chamber,
Means for forming an electric field and a magnetic field in the ionization chamber,
Means for accumulating gas, means for pre-storing a gas amount suitable for starting the discharge for each processing condition of the sample determined by the kind and flow rate of the gas and the strength of the electric field and magnetic field, Means for designating the processing condition, and in response to the designation, the gas amount suitable for the start of the discharge stored in advance corresponding to the designated processing condition is read from the storage means and read. The accumulated gas is divided by the flow rate of the specified gas to obtain the accumulation time, the specified gas is accumulated in the accumulation means during the calculated accumulation time, and the accumulated gas is accumulated in the ionization chamber. And a means for starting the discharge under the specified processing conditions.