JP2002015694A - Rf accelerated ion-implantation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an ion energy value from deviating due to the positional deviation of an apparatus from a magnetic field measuring unit upon maintenance or coping with trouble of the apparatus and from reducing production yield of a semiconductor device. SOLUTION: A first beam current meter 11 and a second beam current meter 12 are provided at a predetermined interval in a path of an accelerated ion beam 2, and ion energy is found by measuring the moving time of the ion beam 2 to control the ion energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an RF acceleration type ion implantation apparatus used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art An RF-accelerated ion implantation apparatus performs impurity doping by converting impurity atoms such as boron B and phosphorus P into ions, applying a high voltage thereto, separating and accelerating the ions, and implanting them into a semiconductor wafer. Things.

As shown in FIG. 4, a conventional RF acceleration type ion implantation apparatus has an ion source 1 for generating an ion beam 2.
And a DC voltage accelerating unit 3 for accelerating the ion beam 2
A mass analysis magnet 4 for selecting the ion beam 2, an RF acceleration unit 6 for accelerating the selected ion beam with high frequency, and an energy analysis magnet 8 for measuring the energy of the accelerated ion beam.
And a disk 13 for holding a wafer 14.

The energy of the bunch (bundle) beam 7 which has passed through the RF accelerating unit and has a high frequency cycle is converted into a magnetic field of the energy analyzing magnet 8 calibrated by using a DC beam whose energy value is known in advance. Measuring unit 9
And the correlation data between the magnetic field intensity B on the theoretical formula and the output value of

For example, as shown in FIG. 5, the ion mass number is m, the charge number is q, the (acceleration) energy is E, the required magnetic field strength on the beam orbit is B, the electron charge is e, and the magnet curvature radius is r. Then, B = (2 mE) ^0.5 / (req)
It can be expressed by the relational expression. At this time, m, r and e
Since q and q are known values, once the required magnetic field strength B is determined, the energy E of the ion beam 2 passing through the magnetic field region can be determined.

As a conventional energy management, the magnet current value (B) of the energy analyzing magnet 8 is sometimes measured by a magnet ammeter 10 and used.

[0007]

However, in the above-described conventional RF-accelerated ion implantation apparatus, the magnetic field measurement unit 9 is fixed to the energy analysis magnet 8 so that the energy analysis magnet 8 can be used for maintenance and troubleshooting. In some cases, such as when the magnetic field measurement unit 9 is displaced or when the magnetic field measurement unit 9 is displaced, an abnormal output value of the magnetic field measurement unit 9 occurs. As a result, an energy shift occurs, the depth and concentration of implanted ions are different, and a characteristic abnormality of the semiconductor device occurs, resulting in a problem of lowering a manufacturing yield.

An object of the present invention is to make it possible to detect an energy shift caused by an abnormal output value of a magnetic field measuring unit by another independent management method, and to confirm this before starting the ion implantation, thereby reducing the production yield of a product. An object of the present invention is to provide an RF-accelerated ion implantation apparatus capable of preventing a decrease.

[0009]

According to a first aspect of the present invention, there is provided an RF-accelerated ion implanter for mass-analyzing a magnet for selecting an ion beam generated from an ion source, and a discontinuous device for accelerating the selected ion beam by a high frequency. In an RF-accelerated ion implanter having an RF accelerating part for bunch beam and a desk for holding a semiconductor wafer into which ions from this RF accelerating part are implanted, two means for measuring the energy of ions of the ion beam are provided. It is characterized by having.

According to a second aspect of the present invention, there is provided an RF-accelerated ion implantation apparatus for selecting an ion beam generated from an ion source, and an RF acceleration for accelerating the selected ion beam with a high frequency to produce a discontinuous bunch beam. Department and
2 provided at predetermined intervals in the path of the bunch beam
And two beam current meters.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an RF accelerated ion implantation apparatus for explaining a first embodiment of the present invention, and FIG.
FIG. 3 is an enlarged configuration diagram near a beam current meter in FIG.

Referring to FIG. 1, the RF of the first embodiment is described.
The accelerated ion implanter includes an ion source 1 for generating an ion beam 2, a DC voltage accelerating unit 3 for accelerating the ion beam 2, a mass analysis magnet 4 for selecting the ion beam 2, and a selected ion. An RF accelerating unit 6 having a resonator 15 for accelerating the beam with a high frequency;
The magnet 8 for measuring the energy of the accelerated ion beam, two beam current meters 11 and 12 provided at predetermined intervals in the path of the ion beam for measuring the velocity of the ion, and the wafer 14 It is mainly composed of a disk 13 to be held. The operation will be described below.

Ion beam 2 generated by ion source 1
Is extracted by the DC voltage acceleration unit 3 and enters the mass analysis magnet 4. The trajectory of the incident ion beam 2 is bent by an electromagnetic field caused by changing a magnet current amount of the mass analysis magnet 4. At this time, according to the current information of the ion beam incident on the beam current meter 5, the ion beam is classified into only ion species necessary for implantation. At this point, the ion beam 2 is transported to the RF acceleration unit 6 as a continuous beam by the DC voltage acceleration unit 3. When the ion beam 2 is incident on the RF acceleration unit 6, the ion beam 2 that has been continuous up to now is accelerated and decelerated by a high frequency, and becomes a bunch beam 7 having a discontinuous high frequency cycle. The bunch beam 7 is accelerated by the plurality of resonators 15 in the RF accelerator 6 while preventing divergence of the beam and adjusting the phase by the plurality of electrostatic quadrupole lenses.

The ion implanter has in advance correlation data of an energy value and an output value of a magnetic field measuring unit 9 installed in the energy analyzing magnet unit 8. Further, the ion implantation apparatus specifies an output value of the magnetic field measurement unit 9 necessary for obtaining energy required for implantation. The electromagnetic field of the energy analysis magnet 8 is adjusted so that the specified output value of the magnetic field measurement unit 9 is obtained. The bunch beam 7 that can pass through the electromagnetic field is measured by the first beam current meter 11, and is determined to have an energy value necessary for injection. At this time, the beam current meter 11
And the current information of the bunch beam 7 incident on the second beam current meter 12 located behind the beam path,
It is double confirmed that the injected bunch beam 7 is accelerated to the required energy. In this state, it is determined that the energy has been adjusted to an appropriate value, and the disc 1
Ion implantation is performed on the wafer 14 located above the wafer 3.

According to the first embodiment configured as described above, the ion energy E of the ion beam is measured by adjusting the electromagnetic field of the energy analyzing magnet 8 (or measuring the magnet current) as in the related art. At the same time, the ion energy E can be double-confirmed by measuring the velocity of the ions with the first beam current meter 11 and the second beam current meter 12 provided in the path of the bunch beam 7. Hereinafter, a method of measuring ion energy will be described with reference to FIG.

The beam current information receiving section 18 obtains information on the ion beam 2 that has become the bunch beam 7 from the high frequency power supply 16. Further, the first beam current meter 11 and the second beam current meter 12 installed at the moving distance d are
Has a configuration that can be moved by the cylinder 17, moves to the beam orbital position when the energy value is determined, and after the adjustment to the required energy value is completed, at the time of actual injection,
It can move out of the beam orbit.

In the bunch beam 7 generated by the high-frequency power supply 16, the beam current amount of about half the diameter of the ion beam passing through the center of the beam orbit is measured by the first beam current meter 1.
First, the other half is measured by the second beam ammeter 12. Beam current information can be obtained from the two beam current meters located at the moving distance d. This 3
Two pieces of information are received by the beam current information receiving unit 18, and among the bunch beams 7 continuously generated, the same bunch beam 7 can be measured by two different types of beam current meters 11 and 12. is there. Based on the information obtained here, the movement time calculator 19 calculates the movement time t (the time elapsed until the bunch beam 7 that has passed through the first beam current meter 11 passes through the second beam current meter 12). Is calculated.

At this point, the desired ion mass number m,
Since the moving distance d (constant) is known, the current energy can be calculated by the energy calculating unit 20. From the obtained result, comparison with a required energy value is performed, and as a next step, if the required energy is obtained, the injection 22 can be performed, and the injection control unit 2
The instruction to start the injection is given by 1 and the first and second beam current meters 11 and 12 move to the position where the injection is possible,
Implantation into the wafer 14 can be performed. When it is determined that the energy value is not the required energy value, the injection control unit 21 instructs the re-beam adjustment 23 to be performed, and the beam adjustment is performed until the required energy value is obtained.

Next, the relational expression of the kinetic energy in the ion implantation apparatus will be described. When the ion mass number is m, the acceleration energy is E, the ion velocity is v, the moving distance is d, and the moving time is t, E = (m × v ² ) / 2 = (m × (d /
t) ² ) / 2 can be represented by a kinetic energy relational expression. At this time, since m and d are known values, the acceleration energy E can be derived if the moving time t during which the bunch beam 7 passes through the moving distance d (constant) is known.

FIG. 3 is a configuration diagram near a beam current measurement meter for explaining a second embodiment of the present invention. Basically, if a hardware configuration capable of detecting the movement time t of the bunch beam 7 passing through the movement distance d (constant) can be obtained, any embodiment is possible. An example in which the shape of the two-beam current meter is changed is shown.

Specifically, a donut-shaped first beam current measuring instrument 11A is mounted on the beam orbit in place of the beam current measuring instrument 11, and the center of the beam orbit is made hollow. The beam current amount located on the outer peripheral portion from the hollow portion is the first
The beam passing through the central portion is measured by the beam current meter 11A, the drive position is adjusted, and the beam is measured by the second beam current meter 12A modified so that the center of the measurement system is located at the center of the beam orbit. As a result, similar processing can be performed without changing other mechanisms.

[0022]

As described above, according to the present invention, the energy management based on the movement time t of the newly provided ion beam allows the energy management magnet to be managed by the output value of the magnetic field measuring unit. Since the added management can be performed, the energy value can be double managed.
In addition, it is possible to detect the energy shift due to the abnormal output value of the magnetic field measurement unit due to the removal of the energy analysis magnet or the position shift of the magnetic field measurement unit at the time of maintenance or troubleshooting, using another independent management method. Is confirmed before the start of ion implantation, it is possible to prevent a decrease in product yield.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention;
FIG. 2 is a configuration diagram of an F-acceleration ion implantation apparatus.

FIG. 2 is an enlarged configuration diagram near a beam current measurement meter.

FIG. 3 is an enlarged configuration diagram in the vicinity of a beam current meter for describing a second embodiment.

FIG. 4 is a configuration diagram of a conventional RF acceleration type ion implantation apparatus.

FIG. 5 is a configuration diagram near an energy analysis magnet for calculating ion energy.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 2 Ion beam 3 DC voltage acceleration part 4 Mass analysis magnet 5 Beam current measurement instrument 6 RF acceleration part 7 Bunch beam 8 Energy analysis magnet 9 Magnetic field measurement unit 10 Magnet ammeter 11 1st beam current measurement instrument 11A 1st beam Current meter 12 Second beam current meter 12A Second beam current meter 13 Disk 14 Wafer 15 Resonator 16 High frequency power supply 17 Cylinder 18 Beam current information receiving unit 19 Moving time calculation unit 20 Energy calculation unit 21 Injection control unit 22 Injection 23 Re-beam adjustment 24 Vacuum chamber

Claims (7)

[Claims] 1. A mass analysis magnet for selecting an ion beam generated from an ion source, and an RF for accelerating the selected ion beam by a high frequency to produce a discontinuous bunch beam
An RF acceleration type ion implantation apparatus having an acceleration section and a desk section for holding a semiconductor wafer into which ions from the RF acceleration section are implanted, is provided with two energy measuring means for the ions of the ion beam. Features RF
Accelerated ion implanter. 2. The RF-accelerated ion implantation apparatus according to claim 1, wherein one of the ion energy measuring means for the ion beam measures the velocity of the ions in the ion beam. 3. The RF-accelerated ion implantation apparatus according to claim 2, wherein the ion energy velocity is measured using two beam current meters provided at predetermined intervals in the path of the ion beam. 4. A mass analysis magnet for selecting an ion beam generated from an ion source, and an RF for accelerating the selected ion beam by a high frequency to produce a discontinuous bunch beam.
An RF-accelerated ion implanter comprising: an accelerating unit; and two beam current meters provided at predetermined intervals in a path of the bunch beam. 5. A first beam current meter injects one half of a bisected beam of a bunch, and a second beam current meter inputs the other half of a beam of a bunch in half. The RF-accelerated ion implantation apparatus according to claim 4, which is configured. 6. The RF according to claim 4, wherein the first beam current meter is configured to make the central portion of the bunch beam incident, and the second beam current meter is configured to make the outer peripheral portion of the bunch beam incident. Accelerated ion implanter. 7. The RF acceleration type according to claim 4, wherein the two beam current meters are configured to be movable from a position of a bunch beam path to a position outside the path by a cylinder. Ion implanter.