JPH07153412A - Ion implanting device - Google Patents

Abstract

PURPOSE:To easily confirm presence/absence of motion abnormality of a holding member and beforehand prevent implantation abnormality due to shortage of overscanning. CONSTITUTION:An overscanning detecting Faraday means 8 for measuring a beam current is provided in the rearward position of a holding member 2 reciprocating across a radiation range of an ion beam 5. Confirmation of overscanning is implemented by an overscanning confirming controller 9 which confirms that the ion beam 5 passes a position of the holding member 2 because of movement of the holding member 2 to be incident upon an overscanning detecting Faraday means 8 in the rear thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus used for manufacturing a semiconductor integrated circuit or the like, and more particularly, to an object to be irradiated with a beam orthogonal to the beam scanning direction while scanning the ion beam electrostatically or electromagnetically. The present invention relates to a hybrid scan type ion implanter that mechanically scans in a direction in which an ion implantation is performed.

[0002]

2. Description of the Related Art An ion implantation apparatus ionizes impurities to be diffused, selectively extracts the impurity ions by a mass spectrometry method using a magnetic field to form an ion beam, and accelerates the ion beam to a predetermined energy if necessary. By irradiating the irradiation target with impurities, the impurities are injected into the beam irradiation target. Since the impurities that determine the characteristics of the device in the semiconductor process can be injected at an arbitrary amount and depth with good controllability, the current It has become an important device for manufacturing semiconductor integrated circuits.

In the above-mentioned ion implantation apparatus, an ion beam is electrostatically or electromagnetically scanned in a predetermined direction (for example, a horizontal direction) in a high vacuum, and the beam irradiation target side is orthogonal to the beam scanning direction. There is a so-called hybrid scan type ion implanter that uniformly implants ions on the entire surface of a wafer by mechanically scanning in a direction (for example, a vertical direction).

In the above-mentioned hybrid scan type ion implantation apparatus, as shown in FIGS. 4 and 5, for example, the ion beam 51 is electrostatically scanned in the horizontal direction by a scanning electrode (not shown) while the wafer 53 is held. The holding member 54 is driven by the drive mechanism 52 via the drive shaft 55 to linearly reciprocate in the vertical direction.

On both sides of the holding member 54 within the beam scanning region (ion beam irradiation range), it is detected whether or not the overscan of the ion beam 51 is normally performed, and the ion implantation dose (dose) is detected. A Faraday cup for measuring quantity, so-called Dose Farade 56, 56 is provided. Then, the host controller 57 makes the implantation amount in the mechanical scan direction constant based on the ion beam current amount (hereinafter, referred to as beam current) measured by one or both of the dose farades 56, 56. Therefore, a control signal (driving pulse) is output to the drive mechanism 52 to control the operation (moving speed) of the holding member 54.

The drive mechanism 52 of the host controller 57
The conventional control for is described in more detail below.

Generally, when the host controller 57 outputs a control signal (driving pulse) to the drive mechanism 52, the controller (not shown) of the drive mechanism 52
While controlling the operation of drive motors such as servo motors,
As a control result, a feedback signal is returned to the host controller 57.

The host controller 57 controls the driving direction and the driving speed of the holding member 54 while determining the vertical scanning position of the holding member 54 from the above feedback signal. Specifically, the holding member 54 driven upward
At a position where the lower end of the holding member 54 completely goes out of the irradiation range of the ion beam 51 (hereinafter, referred to as an overscan position), the speed of the holding member 54 is set to 0 (zero) and the driving direction is switched to the lower direction, and this time to the lower direction. The holding member 5 is moved at a position where the upper end of the driving holding member 54 is completely outside the irradiation range of the ion beam 51 (hereinafter, referred to as an overscan position).
The speed of 4 is set to 0 (zero) and the drive direction is switched to the upper direction.

Then, if the measured beam current value by the dose farade 56 becomes large, the host controller 57
The drive mechanism 52 is controlled so as to increase the vertical movement speed of the holding member 54, and conversely, if the measured beam current value becomes small, reduce the vertical movement speed of the holding member 54.

[0010]

By the way, the drive mechanism 5
2 transmits the power generated by the drive motor to the drive shaft 55 by a power transmission member such as a gear or a shaft, and finally drives the holding member 54 fixed to the end of the drive shaft 55 in the vertical direction. Has become. Therefore, for example, when the gear or shaft of the drive mechanism 52 is broken, the drive motor may be operating normally, but the holding member 54 may not be operating normally. Even in this case, in the above-described conventional configuration, the controller of the drive mechanism 52 sends a normal feedback signal to the host controller 57, so the host controller 57 must detect an abnormality in the vertical driving operation of the holding member 54. Therefore, the injection process will be performed normally. When such a situation occurs and the overscan shortage on the mechanical scan side occurs, there arises a disadvantage that the uniformity of implantation on the surface of the wafer 53 is deteriorated.

Current ion implanters are required to have an implant uniformity with an accuracy of ± 1% or less, and an insufficient overscan causes an immediate implant abnormality.

In order to prevent injection abnormality due to insufficient overscan, a sensor for detecting the position is attached to the holding member 54 itself to confirm that the holding member 54 has moved to the overscan position. Although a method can be considered, in this case, since it is necessary to irradiate the ion beam 51, a sensor that can be used in a high vacuum is required, and a mounting space is very narrow, and it is very difficult to mount the sensor. The current situation is that it has not been realized.

The present invention has been made in view of the above, and an object thereof is to easily confirm the soundness of overscan on the mechanical scan side and prevent injection abnormality due to insufficient overscan. It is to provide an ion implanter capable of

[0014]

An ion implantation apparatus of the present invention drives a holding member for holding a beam irradiation object and the holding member so that the holding member reciprocates while traversing an ion beam irradiation range. Drive means is provided, and in order to solve the above problems, the following means are provided.

That is, the ion implantation apparatus is behind the holding member, and while the holding member is moving within the irradiation range of the ion beam, the ion beam is blocked by the holding member and the ion beam does not enter. Beam current measuring means for measuring the current amount of the ion beam, provided at a position where the ion beam is incident when the member exists at an overscan position outside the irradiation range of the ion beam,
Overscan detection means for detecting whether or not the holding member exists at the overscan position based on the measurement result by the beam current measurement means.

[0016]

According to the above construction, so-called mechanical scanning is performed in which the holding member is driven by the driving means to reciprocate while traversing the irradiation range of the ion beam. Beam current measuring means for measuring the current amount of the ion beam (beam current) is provided at the rear position of the holding member, and when the holding member exists at the overscan position outside the irradiation range of the ion beam. The ion beam is incident on the beam current measuring means to measure the beam current, and the overscan detecting means detects that the holding member is present at the overscan position based on the measurement result.

As described above, the confirmation of the overscan position of the holding member (the confirmation of the overscan of the mechanical scan) is performed by moving the holding member and moving it out of the irradiation range of the ion beam, so that the ion beam moves to the position of the holding member. Since it is performed by confirming that it passes and is incident on the beam current measuring means behind it, there is no need to attach a sensor for detecting its position to the holding member, and the holding member is overscanned. You can easily confirm that you are moving to the position.

As a result, for example, when the gears and shafts of the drive means are broken and the drive motor is operating normally, but the power of the drive motor is not normally transmitted to the holding member, resulting in insufficient overscan. However, the overscan abnormality can be detected, and the injection abnormality due to insufficient overscan can be prevented in advance.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS. 1 and 2.

In the ion implantation apparatus according to this embodiment, as shown in FIG. 2, the spot-shaped ion beam 5 is horizontally scanned in parallel by the first scanning electrodes 11a and 11b and the second scanning electrodes 12a and 12b. On the other hand, as shown in FIG. 1, a holding member 2 holding a wafer 1 as a beam irradiation target is driven by a driving mechanism 3 as a driving means via a driving shaft 4 to cross the irradiation range of the ion beam 5. In this way, the so-called hybrid scan system is used, which performs linear reciprocating motion in the vertical direction.

As shown in FIG. 2, a scanning voltage of a substantially triangular wave having a phase difference of 180 degrees from each other is applied from the scanning power source 13 to the first scanning electrodes 11a and 11b arranged to face each other in parallel. In addition, the second scanning electrodes 12a and 12b that are arranged in parallel and face each other are connected to each other by the scanning power source 13 and
A scanning voltage having a substantially triangular waveform with a phase difference of 0 degrees is applied. Then, the first scan electrode 11a and the second scan electrode 12b
The same scan voltage is applied to the first scan electrode 1 and
The same scanning voltage is applied to 1b and the 2nd scanning electrode 12a. As a result, the spot-like ion beam that passes through substantially the center between the first scan electrodes 11a and 11b scans horizontally in a fan shape by the electric field between the first scan electrodes 11a and 11b, and then the second scan. A parallel beam is formed by the electrodes 12a and 12b.

Further, on both sides of the holding member 2 in the beam scanning region (ion beam irradiation range), it is detected whether or not the overscan of the ion beam 5 is normally performed, and the ion implantation amount (dose) is detected. A dose Farade 6.6 for measuring the quantity is provided.

Further, as shown in FIG. 1, the ion implanter is based on the amount of ion beam current (hereinafter referred to as beam current) measured by one or both of the above dose farades 6 and 6. Then, a control signal (driving pulse) is output to the drive mechanism 3 so that the injection amount in the mechanical scan direction is constant, and the operation (moving speed) of the holding member 2 is controlled by a microcomputer or the like. It is equipped with a host controller 7.

The drive mechanism 3 basically comprises a drive motor such as a servo motor (not shown), a power transmission member such as gears and shafts, and a controller for controlling the operation of the drive motor. Then, the controller of the drive mechanism 3 receives the control signal from the host controller 7, controls the operation of the drive motor, and returns a feedback signal to the host controller 7 as the control result.

The host controller 7 controls the driving direction and the driving speed of the holding member 2 while judging the position of the holding member 2 in the vertical direction based on the feedback signal from the driving mechanism 3.

Further, in this embodiment, as shown in FIGS. 1 and 2, whether the overscan of the holding member 2 is normally performed at the rear position of the holding member 2 within the irradiation range of the ion beam 5. For the purpose of detecting whether or not there is provided an overscan detection farade 8 as a beam current measuring means for measuring the beam current of the ion beam 5.

The overscan detection farade 8 is present at a position (hereinafter, referred to as an overscan position) where the holding member 2 driven in the vertical direction is completely outside the irradiation range of the ion beam 5. At this time, it is necessary to provide the ion beam 5 at a position where it enters the Faraday cup. For example, when the Farade 8 for overscan detection is installed behind the center of the holding member 2 (on the central axis of the beam), the holding member 2 is driven even when the holding member 2 which is driven upward reaches the overscan position. The ion beam 5 is blocked by the drive shaft 4, and the ion beam 5 does not enter the overscan detection farade 8. Therefore,
As shown in FIG. 2, a farade 8 for overscan detection
Means that the ion beam 5 surely enters when the holding member 2 is at the overscan position, while the ion beam 5 is not incident on the holding member 2 at a position other than the overscan position so that the ion beam 5 is blocked. It is provided at a position displaced from the center axis of the beam by at least the radius of the drive shaft 4.

In the ion implanter, as shown in FIG. 1, the overscan of the holding member 2 is normally performed on the basis of the beam current measured by the above Farade 8 for detecting overscan. It is provided with an overscan confirmation controller (overscan detection means) 9 configured by a microcomputer or the like that outputs an interlock signal to the host controller 7 when it is determined that there is an overscan abnormality.

The operation of the ion implanter having the above structure will be described below.

First, as a preparatory step, before setting the wafer 1 on the holding member 2 and starting the actual implantation process, the holding member 2 is made to stand by at the overscan position, and the farscan 8 for overscan detection is set. The beam current amount of the incident ion beam 5 is measured. Then, the overscan confirmation controller 9 stores in the internal memory the beam current amount I _f measured by the overscan detection farade 8 before the start of implantation.

After the above preparation is completed, the actual injection process is started. That is, as shown in FIG. 2, a spot-shaped ion beam 5 extracted from an ion source (not shown), mass-analyzed by an analysis magnet, and further accelerated or shaped as necessary is generated by the first scanning electrode 11a. 11
b and the second scanning electrodes 12a and 12b perform parallel scanning in the horizontal direction. The beam current of the ion beam 5 is taken into the host controller 7 via the dose farade 6. The host controller 7 outputs a control signal to the drive mechanism 3 so that the implantation amount in the mechanical scan direction is constant, and controls the moving speed when the holding member 2 crosses the irradiation range of the ion beam 5 up and down. To do. Specifically, when the measurement beam current by the dose Faraday 6 becomes large, the vertical movement speed of the holding member 2 is increased, and conversely, when the measurement beam current becomes small, the movement speed is decreased.

In the drive mechanism 3, the internal controller controls the rotation of the drive motor based on the control signal from the host controller 7, and returns a feedback signal to the host controller 7 as a control result. The host controller 7 determines the scan position of the holding member 2 from the feedback signal, sets the speed of the holding member 2 to 0 (zero) at the overscan position, and switches the driving direction from top to bottom or from bottom to top. , And outputs a timing signal indicating the timing at which the holding member 2 exists at the overscan position to the overscan confirmation controller 9.

Overscan confirmation controller 9
Is the beam current amount I _i of the ion beam 5 incident on the overscan detection farade 8 and the beam current amount before the start of implantation stored in the internal memory each time a timing signal is input from the host controller 7. Compare with I _f . That is, the following equation (1) is calculated to obtain the ratio R between the two.

R = I _f / I _i (1) Then, in the overscan confirmation controller 9, the ratio R obtained by the above calculation performed each time a timing signal is input is within a predetermined reference range (eg, , 0.8 to 1.2), it is considered that the mechanical overscan is normal, while when the above ratio R is out of the predetermined reference range,
The mechanical overscan is regarded as abnormal, and the interlock signal is output to the host controller 7. When the ratio R is out of the reference range, the ion beam 5 is blocked by the holding member 2 and only a few percent of the beam is incident on the overscan detection farade 8 because the overscan is not sufficiently performed (or It is considered that the beam current amount I _i is smaller than the beam current amount I _f before the start of the injection because the beam current I _i is not incident at all.

The overscan confirmation controller 9 always monitors the beam current measured by the overscan detection farade 8 even when the timing signal is not input. Even if a beam current of a predetermined reference current amount (a value close to zero) or more is measured by the overscan detection farade 8 during the non-operation period, it is regarded as a mechanical scan abnormality and an interlock signal is output to the host controller 7. . At a position other than the overscan position where the timing signal is not generated, the ion beam 5 is blocked by the holding member 2 and should not be incident on the overscan detection farade 8, but the beam current is measured by the overscan detection farade 8. Is the upper controller 7
It is conceivable that the holding member 2 is at the overscan position (for example, is not driven at all and is stopped at the overscan position) without following the control of 1).

Upon receiving the interlock signal from the overscan confirmation controller 9, the host controller 7 immediately stops the injection operation.

The overscan position of the holding member 2 is when the holding member 2 is above the ion beam 5.
There are two positions below the ion beam 5, but the basic overscan checking operation is the same at both positions.

By the way, the ratio R deviates from the reference range because the ion beam 5 is blocked by the holding member 2 because the overscan is not sufficiently performed, and only a few percent of the beam is detected by the overscan detection farade 8. In addition to the case where the beam does not enter, an abnormality of the beam itself (fluctuation of the beam current) is considered, and the overscan confirmation controller 9 outputs the interlock signal even when the abnormality of the beam occurs. That is, the presence / absence of a beam abnormality is detected by both the dose Faraday 6 and the overscan detection Farade 8, and the reliability can be improved.

As described above, the ion implantation apparatus of this embodiment has the holding member 2 for holding the wafer 1 and the holding member 2 described above.
Drive mechanism 3 for driving holding member 2 so as to reciprocate while traversing the irradiation range of ion beam 5, and behind holding member 2 holding member 2 moves within the irradiation range of ion beam 5. The ion beam 5 is blocked by the holding member 2 so that the ion beam 5 does not enter, and the ion beam 5 is provided at a position where the ion beam 5 enters when the holding member 2 is in an overscan position outside the irradiation range of the ion beam 5. And detecting whether or not the holding member 2 exists at the overscan position based on the overscan detection farade 8 for measuring the current amount of the ion beam 5 and the measurement result by the overscan detection farade 8. And a controller 9 for overscan confirmation.

According to the above structure, the confirmation of the overscan position of the holding member 2, that is, the confirmation of the overscan on the mechanical scan side is performed by moving the holding member 2 out of the irradiation range of the ion beam 5. This is performed by confirming that the ion beam 5 has passed the position of the holding member 2 and is incident on the overscan detection farade 8 behind it. For this reason,
It is possible to easily confirm that the holding member 2 has moved to the overscan position without attaching a sensor for detecting the position to the holding member 2.

As a result, for example, the gears and shafts of the drive mechanism 3 are broken and the drive motor is operating normally, but the power of the drive motor is not normally transmitted to the holding member 2, resulting in insufficient overscan. Even if there is, an overscan abnormality can be detected, and an injection abnormality due to insufficient overscan can be prevented in advance.

In the above embodiment, when the overscan confirmation controller 9 detects an overscan abnormality on the mechanical scan side, an interlock for immediately stopping the injection operation is applied.
It is not limited to this. For example, when the overscan confirmation controller 9 detects an overscan abnormality, an alarm operation such as an abnormality display or an alarm sounding is performed on a display unit (not shown), and the operator himself operates to stop the injection operation. The configuration may be such that

In the above embodiment, the first scan electrode 11
Although the ion beam 5 is scanned in parallel by using a. 11b and the second scanning electrodes 12a and 12b,
The present invention is not limited to this, but the first scan electrode 11a.
It is also possible to irradiate the wafer 1 with an ion beam that scans in a fan shape using only 11b. Further, the beam scanning may be performed electromagnetically by using a deflection electromagnet instead of electrostatically performing the beam scanning by the scanning electrodes.

In the above embodiment, the drive mechanism 3 axially drives the drive shaft 4 provided in the vertical direction, whereby the holding member 2 fixed to the end of the drive shaft 4 is linearly moved in the vertical direction. Although it is configured to reciprocate, it is not limited to this. That is, the holding member 2 has only to reciprocate while traversing the irradiation range of the ion beam 5. For example, as shown in FIG. 3, the driving mechanism 3'swings the driving shaft 4'and swings the driving shaft 4 '. The holding member 2 fixed to the end of the can also be configured to reciprocate on an arcuate trajectory. In this case, since the drive shaft 4'does not block the ion beam 5, the degree of freedom of the place for installing the overscan detection farade 8 is increased. The shaded area in the figure indicates the irradiation range of the ion beam 5.

The above-mentioned embodiments are intended to clarify the technical contents of the present invention, and should not be construed in a narrow sense by limiting only to such specific examples. Various modifications can be made within the scope of the claims.

[0046]

As described above, the ion implantation apparatus of the present invention is shielded by the holding member when the holding member is moving behind the holding member and within the irradiation range of the ion beam. Is not incident, while the holding member is provided at a position where the ion beam is incident when the holding member is present at an overscan position outside the irradiation range of the ion beam, and a beam current measuring means for measuring the amount of current of the ion beam. And an overscan detecting means for detecting whether or not the holding member is present at the overscan position based on the measurement result by the beam current measuring means.

Therefore, the confirmation of the overscan position of the holding member (the confirmation of the overscan of the mechanical scan) is performed by moving the holding member and moving it out of the irradiation range of the ion beam, so that the ion beam passes through the position of the holding member. Since it is performed by confirming that the beam current is incident on the beam current measuring means behind it, there is no need to attach a sensor for detecting its position to the holding member, and the holding member is not overscanned. You can easily confirm that you are moving up to. Therefore, for example, the gears and shafts of the drive means are broken and the drive motor is operating normally, but even if the power of the drive motor is not normally transmitted to the holding member and overscan is insufficient, the It is possible to detect the scan abnormality and prevent the injection abnormality due to the insufficient overscan.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention and is a schematic configuration mainly on a mechanical scan side in a hybrid scan type ion implantation apparatus.

FIG. 2 is a plan view showing a schematic configuration mainly on a beam scan side in the ion implantation apparatus.

FIG. 3 is an explanatory diagram showing an example of another mechanical scanning method in the ion implantation apparatus.

FIG. 4 is a plan view showing a schematic configuration of a main part of a conventional hybrid scan type ion implantation apparatus.

FIG. 5 is a block diagram showing a schematic configuration mainly on a mechanical scan side in the conventional ion implantation apparatus.

[Explanation of symbols]

1 Wafer (Beam Irradiation Target) 2 Holding Member 3 Drive Mechanism (Drive Means) 4 Drive Axis 5 Ion Beam 6 Dose Farade 7 Upper Controller 8 Farade for Overscan Detection (Beam Current Measuring Means) 9 Overscan Confirmation Controller (Overscan) Detection means)

Claims (1)

[Claims] 1. An ion implantation apparatus comprising: a holding member for holding a beam irradiation target; and a driving unit for driving the holding member so that the holding member reciprocates while traversing an ion beam irradiation range. Behind the holding member, when the holding member is moving within the irradiation range of the ion beam, the holding member is blocked and the ion beam does not enter, while the holding member is out of the irradiation range of the ion beam. When the ion beam is incident on the position, the beam current measuring means for measuring the amount of current of the ion beam, and the holding member is overloaded based on the measurement result by the beam current measuring means. An ion implanter, comprising: an overscan detection means for detecting whether or not the scanning position exists.