JPH07153416A - Charged particle implanting device - Google Patents

Abstract

PURPOSE:To flatten a profile of a charged particle beam so as to prevent generation of charge-up on a substrate such as a semiconductor wafer. CONSTITUTION:A beam detecting probe 16 disposed in front of a substrate 14 can be disposed on a path of a beam 10, as necessary. In the case where a profile of the beam is found not to be flat as a result of detection by the probe, a magnetic field device 4 provided before the probe is controlled to change the beam into a flat profile. Since the probe is disposed in front of the substrate, most of beams can pass through the probe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle implanter used for implanting charged particles into a substrate such as a semiconductor wafer, and more particularly to an ion implanter for implanting ions in the form of a beam.

[0002]

2. Description of the Related Art Recently, in this type of ion implantation apparatus, it is required to shorten the ion implantation time to improve the productivity of semiconductor devices. In order to meet such a demand, it is necessary to increase the beam current amount. On the other hand, it is desirable that the distribution of the ion beam injected into the semiconductor wafer, that is, the profile is as uniform as possible in order to prevent the semiconductor wafer from being charged.

However, when the beam current amount is increased, the profile of the ions implanted into the semiconductor wafer tends to be locally high in the central portion of the ions, so that the semiconductor wafer is inevitably charged.

Therefore, it is extremely important to monitor the profile of the ion beam. Various techniques have been proposed in the past for monitoring the profile of the beam, but most of these techniques use a beam profile monitor placed at the rear of the semiconductor wafer to measure the profile of the ion before ion implantation. Is detected and the ion profile is controlled according to the result.

[0005]

However, the profile of the ion beam is not always the same as that before the implantation, but often changes from moment to moment. Therefore,
As described above, the technique of detecting the profile of ions at the rear of the semiconductor wafer before implanting ions has a drawback in that the profile of the ion beam during ion implantation cannot be detected and monitored.

An object of the present invention is to provide a charged particle implanting apparatus capable of detecting and monitoring the profile of an ion beam implanted in a substrate even during ion implantation.

Another object of the present invention is to provide an ion beam implanting apparatus which can make the profile of ions uniform during ion implantation and prevent charging on a semiconductor wafer.

Still another object of the present invention is to provide a beam detection probe capable of detecting an ion profile during ion implantation.

[0009]

According to the present invention, in a charged particle injection apparatus for injecting charged particles into a substrate to be processed, a charged particle beam arranged in front of the substrate and injected into the substrate A magnetic field device for controlling the size, and a magnetic field device provided between the magnetic field device and the substrate, configured to move in a direction transverse to the charged particle beam that has passed through the magnetic field device and to transmit the charged particle beam. A beam detection probe, a drive mechanism for moving the beam detection probe in the charged particle beam direction, and a charge-up of the substrate due to an injected charged particle beam depending on a detection result of the beam detection probe. And a control unit for controlling the magnetic field device.

Further, according to the present invention, in the charged particle implanting apparatus, which is arranged in front of the substrate to be processed and includes a magnetic field device for controlling the size of the charged particle beam injected into the substrate, the charged particle beam A beam profile monitor for detecting the profile of 1 is provided between the substrate and the magnetic field device to obtain a charged particle implanting device.

[0011]

According to the present invention, a beam detection probe that operates as a beam profile monitor is arranged in front of a substrate such as a semiconductor wafer to be implanted with ions, and the beam detection probe is moved across the ion beam. , Drive mechanism to move. In addition, the beam detection probe itself is configured to be able to transmit an ion beam, and this enables the ion detection to be performed even during ion implantation.
The ion beam profile can be monitored if desired.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a charged particle implanter according to an embodiment of the present invention is used as an ion implanter.
As shown in FIG. 1, the illustrated ion implantation apparatus includes a guide chamber 11 for guiding an ion beam 10 from an ion source (not shown), a monitor chamber 12 for monitoring the ion beam 10 from the guide chamber 11,
And a processing chamber 13 for actually performing ion implantation, and these guide chamber 11, monitor chamber 12, and processing chamber 13 are hermetically connected to each other.

In the illustrated embodiment, a quadrupole magnet 15 is arranged as a magnetic field device outside the guide chamber 11 adjacent to the monitor chamber 12,
The size of the ion beam 10 in the cross-sectional direction can be controlled by the quadrupole magnet 15 as described later. Further, a beam detection probe 16 having a structure described later is positioned in the monitor chamber 12 so as to be movable in a direction traversing the ion beam 10, that is, in the vertical direction of FIG. The profile of the ion beam 10 in the cross-sectional direction, that is, the distribution can be detected, and most of the ion beam 10 can be transmitted or passed. A Faraday cup 17 for detecting the amount of current caused by the ion beam is provided behind the beam detection probe 16 in the monitor chamber 12, that is, on the side of the processing chamber 13 so as to be movable in the vertical direction of FIG. There is. On the other hand, in the processing chamber 13, a support plate 18 having a plurality of semiconductor wafers mounted thereon as substrates to be processed is rotatably attached to a rotation shaft.

Further, a drive mechanism 20 is connected to the beam detection probe 16, and the drive mechanism 2 in this example is used.
0 is driven by air. The detection result detected by the beam detection probe 16 is given to the control unit 22 as an electric signal. The control unit 22 controls the current supplied to the quadrupole magnet 15 according to the detection result of the beam detection probe 16,
Control is performed so that the profile in the 0 cross section is as flat as possible.

This means that the quadrupole magnet 1 is designed so that the profile of the ion beam 10 in the sectional direction does not become extremely large locally in the central portion of the beam.
It is meant to control the quadrupole magnetic field generated by 5. When the control as described above is performed, the profile in the cross-sectional direction of the ion beam 10 becomes substantially flat as described below, and as a result, the substrate 14 such as a semiconductor wafer is prevented from being excessively charged up. can do.

Therefore, in the structure in which the detection result of the beam detection probe 16 is fed back to the quadrupole magnet 15, it is possible to prevent the substrate 14 from being damaged as a result of charge-up.

More specifically, the control unit 22 shown in FIG.
Has a current density calculation unit 221 for calculating the current density supplied to the quadrupole magnet 15 according to the detection result from the beam detection probe 16, and is further electrically connected to the beam detection probe 16 for beam detection. A probe control unit 222 that operates as an interface between the probe 16 and the current density calculation unit 221 and a magnet control unit 223 that operates as an interface between the current density calculation unit 221 and the quadrupole magnet 15 are provided. Further, the illustrated control unit 22 is provided with an input / output device 224 operated by an operator.

Referring now to FIG. 2, the magnetic pole arrangement of the quadrupole magnet 15 is shown. According to this magnetic pole arrangement, the ion beam 1 passing through the quadrupole magnet 15 is shown.
0 (here, a positive ion beam) is given a force f that converges the ion beam 10 in the vertical direction, and a force f that diverges the ion beam 10 in the horizontal direction. You can

Next, referring to FIG. 3, in the quadrupole magnet 15 shown in FIG. 2, the ion beam 10 is injected into the wafer 14 in a state of being diverged in the horizontal direction, while it is injected in the vertical direction. It is designed so that the ion beam 10 is once focused on the rear focus of the quadrupole magnet 15 and then injected into the wafer 14 in a divergent state. By controlling the current supplied to the quadrupole magnet 15, the intensity of the quadrupole magnetic field is controlled, which allows the ion beam 10 to be adjusted as shown by the solid and dashed lines in FIG.

Referring to FIG. 4, the beam detection probe 1
6 is shown, and here, a frame 161 surrounding a space having a size capable of containing an ion beam,
The frame 161 is provided with a support portion 162 that connects the drive mechanism 20 (FIG. 1). Also, the frame 161
In the inner space of the three wires 166, 167, 168
Is stretched, and when the ion beam hits each wire,
An electric current flows according to the intensity of the ion beam. In the illustrated example, two wires 166 and 167 intersect each other obliquely, and the remaining wire 168 is fixed to the frame 161 so as to be orthogonal to the moving direction of the beam detection probe 16 indicated by the arrow. Has been done. The current from each wire is connected to the probe control unit 222 via a lead wire (not shown). Three wires 166,
The algorithm for processing the output currents from 167 and 168 has been described in detail in Japanese Patent Application No. 3-45668, so the description is omitted here.

When the beam detection probe 16 using the above-mentioned three wires is used in the ion implantation apparatus of FIG.
Since most of the ion beam passes through this probe 16, the beam detection probe 16 is provided in the path of the ion beam 10 even during the period of implanting ions into the wafer 14.
Can be inserted as necessary to detect the profile of the ion beam 10.

Beam detection probe 1 used in the present invention
As for 6, it is sufficient that the ion beam can be transmitted or passed therethrough. Therefore, in FIG.
Various types of beam profile monitors can be applied, such as those using only 66 and 167, or those in which more wires are fixed in parallel to the frame.

Here, the control unit 22 shown in FIG. 1 performs a control operation for flattening the profile of the ion beam 10 in the cross-sectional direction. Below, this control operation is shown in FIG.
The description will also be made with reference to. When the suppression of the peak current density is instructed by the operator of the input / output device 224 (step S1), the beam detection probe 16 causes the ion beam 10 to move.
Beam profile is measured by x-
It is performed on the y coordinate, and the beam current density I _{B at} each coordinate position is calculated by the current density calculation unit 221 according to a predetermined algorithm (step S2). Next, of the beam current densities I _B at each coordinate position, the maximum current density I _B max is calculated by the current density calculation unit 221 (step S3).

Further, the current density calculation unit 221 compares the calculated maximum current density I _B max with a predetermined specified value I _B0 (step S4), and the maximum current density I _B ma
When x is smaller than the predetermined specified value I _B0 , the process ends. In this way, when the maximum current density I _B max is smaller than the predetermined specified value I _B0 , in this example, it is determined that the spatial spread of the ion beam is substantially uniform or flat. It will be.

On the other hand, when the maximum current density I _B max is larger than a predetermined specified value I _B0 , the current density calculation unit 221 controls the magnet control unit 223 to increase the predetermined increase Δa of the magnet current.
The magnet current setting value is increased only by (A) (step S5). Hereinafter, this operation is repeated until the maximum current density I _B max becomes smaller than a predetermined specified value I _B0 . In this embodiment, the increase Δa of the magnet current is
(A) is configured so that it can also be set by the operator.

By controlling the magnet current in this manner, the peak value in the profile of the ion beam 10 in the cross-sectional direction can be reduced, and as a result,
The profile of the ion beam will be flattened. Therefore, it is possible to prevent a trouble such as damage of a substrate such as the wafer 14 due to charge-up.

For example, assume that the profile in the cross-sectional direction of the ion beam 10 has a high distribution in the central portion and a low distribution in the peripheral portion, as shown in FIG. In this case, if the control according to the present invention is not performed, the profile will have a distribution as shown in FIG. 7A in the AB cross section of FIG. In this case, there is a portion with a current density higher than the allowable limit in the central portion of the beam spot, and the current density in this portion is the main cause of charge-up on the wafer 14.

On the other hand, in the present invention, by controlling the magnetic field generated by the quadrupole magnet 15, the ion beam spot is expanded and flattened as shown in FIG. 7 (b). In this way, even if the ion beam spot is widened, the total amount of the ion beam does not change. Therefore, it is possible to suppress charge-up and control so that the implantation time does not become long.

In FIG. 5, the maximum current density I _{B of the} beam current is
Although max is detected, the present invention is not limited to this, and the same control can be performed by using the median of the beam current or a statistic amount such as the area where the current density becomes a certain value or more. You can

Although the above-described embodiments have been described only with respect to ion implantation, the present invention can be applied to the implantation of other charged particles such as electrons.

[0031]

According to the present invention, since the beam detection probe that functions as a beam profile monitor can be inserted in the beam path in front of the substrate to be processed, if necessary, even during ion implantation, There is an advantage that the beam profile can be detected and the change of the beam profile can be dealt with in real time. Further, since the magnetic field positioned in front of the beam detection probe is controlled according to the detection result of the beam profile, feedback control is performed, and accurate control can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an ion implantation apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a magnetic pole arrangement of the quadrupole magnet shown in FIG.

FIG. 3 is a diagram for explaining the operation of the quadrupole magnet shown in FIG.

FIG. 4 is a diagram showing an example of a beam detection probe used in the ion implantation apparatus of FIG.

5 is a flow chart for explaining a control operation of the ion implantation apparatus of FIG.

FIG. 6 is a diagram for explaining an example of an ion beam distribution.

FIG. 7A is a diagram showing a beam current density when the control according to the present invention is not performed. (B) is a diagram showing a beam current density when the control according to the present invention is performed.

[Explanation of symbols]

 10 Ion Beam 11 Guide Chamber 12 Monitor Chamber 13 Processing Chamber 14 Wafer 15 Quadrupole Magnet 16 Beam Detection Probe 17 Faraday Cup 18 Support 20 Drive Mechanism 22 Control 221 Current Density Calculation Unit 222 Probe Control Unit 223 Magnet Control Unit 224 Input Output device

Claims (6)

[Claims] 1. A charged particle injection device for injecting charged particles into a substrate to be processed, which is arranged in front of the substrate and which controls a spatial spread of a charged particle beam injected into the substrate. A beam detection probe that is provided between the magnetic field device and the substrate, is movable in a direction transverse to the charged particle beam that has passed through the magnetic field device, and is capable of transmitting the charged particle beam; A drive mechanism that moves the beam detection probe in the charged particle beam direction, and controls the magnetic field device so as to prevent charge-up of the substrate due to the injected charged particle beam in accordance with the detection result of the beam detection probe. A charged particle implanting device, comprising: 2. The beam detecting probe according to claim 1, wherein the beam detecting probe is mechanically movably connected to a frame having a space having a size capable of enclosing a charged particle beam inside and the driving mechanism. A supporting part, at least two conductive wires fixed to the frame so as to traverse the charged particle beam, and wiring for electrically connecting each wire to the control part. A charged particle injection device characterized by the above. 3. The wire according to claim 2, wherein the conductive wires are fixed to the frame and two wires fixed to the frame so as to intersect each other and diagonally cross the charged particle beam. And a wire fixed to the frame in a direction intersecting the moving direction of the beam detection probe. 4. The charged particle implanting device according to claim 1, wherein the charged particle beam is an ion beam. 5. A beam detection probe used in a charged particle implanting device for injecting charged particles into a substrate to be processed, wherein the beam detection probe can be moved in the direction of the charged particle beam, wherein the charged particle beam is enclosed inside. A frame having a space having a size capable of forming a beam, two wires fixed to the frame so as to intersect each other and diagonally cross the charged particle beam, and the wire fixed to the frame and the beam. A beam detection probe comprising: a wire fixedly exposed to the frame in a direction perpendicular to the moving direction of the detection probe. 6. A charged particle implanter comprising a magnetic field device which is disposed in front of a substrate to be processed and which controls a spatial spread of a charged particle beam injected into the substrate,
The charged particle implanting device, wherein a beam profile monitor for detecting the profile of the charged particle beam is provided between the substrate and the magnetic field device.