JP2591415Y2 - Beam current measuring device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam current measuring device provided in, for example, an ion implanter for measuring an ion beam current, and more particularly to a beam current measuring device having a plurality of beam collectors.

[0002]

2. Description of the Related Art An ion implantation apparatus ionizes impurities to be diffused, selectively extracts these impurity ions by mass spectrometry using a magnetic field to form an ion beam, accelerates the ion by an electric field, and irradiates an ion irradiation target. This means that impurities are implanted into the ion irradiation target, and the impurities that determine the characteristics of the device in the semiconductor process can be implanted at an arbitrary amount and depth with good controllability. Device.

[0003] The ion implantation apparatus described above is designed to be capable of coping with a large ion irradiation target such as an 8-inch wafer, for example, by electrically scanning an ion beam in a predetermined direction (for example, a horizontal direction) and ion irradiation. There is a so-called hybrid scan system in which uniform injection is performed over the entire surface of the wafer by mechanically scanning the object side in a direction orthogonal to the beam scanning direction.

In the above-described hybrid scan type ion implantation apparatus, as shown in FIG. 4, an ion beam 51 scanned in a horizontal direction by a scanning electrode (not shown) is applied to an irradiation mask 52 disposed upstream of the implantation position. A sample 56 such as a wafer held on a sample fixing table 55 which passes through the injection opening 52a and is driven by a driving mechanism (not shown) at the injection position and reciprocates vertically (in a direction perpendicular to the paper surface). Irradiated.

The injection opening 5 in the irradiation mask 52
2a, a Faraday aperture 52 is provided on both sides in the beam scanning direction.
A b.52c is drilled, and a dose farad 53 and a monitor farad 54 are provided behind (downstream).

Downstream from the injection position, there is provided a multipoint Faraday 57 in which a number of small Farades 64 (see FIG. 5) as beam collectors are arranged in the beam scanning direction. When the ion beam 51 is at a position outside the irradiation area, the scanned ion beam 51 is incident on the Faraday 64 of the multipoint Farade 57.

The dose Faraday 53 and the multipoint Faraday 57 are provided with a switching relay 58 and a current integrator (hereinafter referred to as C / I) 59 for integrating the inflow current.
Is connected to the control device 60 via the. Control device 60
Controls the switching relay 58 to switch the beam measurement position to the dose Faraday 53 or the multi-point Farade 57,
The beam current of the ion beam 51 incident on them is measured. Then, as previously proposed by the present inventor (Japanese Patent Application No. Hei 3-208094), the control device 60 fixes the sample based on these measurement results so that the injection amount in the mechanical scan direction is constant. The operation of the table 55 is controlled.

As shown in FIG. 5, the multi-point Faraday 57 includes a plurality of Farades 64, an irradiation mask 62 having a plurality of beam incident holes 62a corresponding to the Farades 64, In order to prevent the leakage of secondary electrons, Faraday 6
4 and a suppressor electrode 63 provided near the opening. Conventionally, all the Farades 64 are connected in parallel, and the ion beams 51 incident on each of the Farades 64 are combined into one and input to the C / I 59 via the switching relay 58 for beam current measurement. You.

[0009]

However, in the above-described conventional configuration, a certain Farade 64 is selected from among the Farades 64.
The wire connected to the Faraday 64
Even if there is a ground fault, it cannot be detected. Therefore, when the above-described abnormality occurs, the measured value of the beam current becomes lower than the actual beam current.
For example, in the case where the multi-point Faraday 57 is composed of ten Farades 64..., If there is no input for one of them, the measured value of the beam current becomes about 10% lower than the actual beam current. It will be lower. Since the beam current measured in such a multipoint Faraday 57 is used for correcting the implantation dose, in this case, the influence on the implantation dose control reaches about 10%, and the dose actually implanted is reduced. It changes greatly.

[0010] Considering that the allowable error range in the current injection amount control of the ion implantation apparatus is about 0.5%,
The effect of as much as 10% as described above is a major problem.

The present invention has been made in view of the above, and an object of the present invention is to provide a beam current measuring apparatus having a large number of beam collectors, such as the above-mentioned multipoint Faraday, which can shorten the abnormality of the beam collector such as disconnection or ground fault. It is an object of the present invention to provide a beam current measuring device capable of detecting time.

[0012]

In order to solve the above-mentioned problems, a beam current measuring device according to the present invention comprises a plurality of beam collectors, for example, a Faraday gauge, and a beam for detecting a beam current of a beam incident on the beam collector. In the beam current measuring device provided with the current detecting means, the following means are taken.

That is, the plurality of beam collectors are divided into a plurality of groups, and at least one
The beam collector included in the pump is set to multiple
In addition, switching means for switching connection and disconnection between each of the divided groups and the beam current detection means is provided , and further, based on the beam current value of each of the groups.
Abnormality detection to detect abnormalities of the beam collector
Means .

[0014]

According to the above configuration, the plurality of beam collectors are divided into a plurality of groups, with some (or even one) beam collector being the same group. Further, a switching unit for switching connection and disconnection with the beam current detection unit is provided for each group.

While irradiating a predetermined beam to each beam collector and turning on one of the switching means connected to each group and turning off the other switching means,
Only the beam current incident on the beam collector belonging to a certain group is input to the beam current detecting means. Similarly, by switching the switching means sequentially while irradiating the same beam to each beam collector, the beam current value for each group can be measured. Further
In addition, the abnormality detecting means is based on the beam current value of each group.
And detects an abnormality of the beam collector.

For example, when an electric wire connected to a certain beam collector is disconnected or a certain beam collector is grounded, a beam current value measured by a group to which such an abnormal beam collector belongs is normally set. It is smaller than that. Therefore, since the ratio of the beam current values of each group also changes, an abnormality of the beam collector can be detected from the change of the ratio.

[0017] In this way, as long required beam current value of each group, Ru can be used to confirm the presence or absence of an abnormality of the beam collector. In addition, videos included in one group
Beam collectors are set to multiple
Compared to placing collectors in different groups
Thus, the number of groups to be divided is reduced . As a result, abnormality detection can be performed in a short time.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The beam current measuring apparatus of the present embodiment is used for controlling the implantation dose in an ion implantation apparatus of a hybrid scan system, but is not limited to this.

In the above-described ion implantation apparatus, a spot-like ion beam extracted from the ion source and subjected to mass analysis, acceleration, and the like, as necessary, is fed from a sweep power source to each other.
A triangular scan voltage having a phase difference of 80 degrees is applied 2
Parallel scanning is performed in the horizontal direction by a set of parallel plate electrodes.

As shown in FIG. 2, the end station of the ion implantation apparatus is provided with a sample holder 5 for holding a sample 6 such as a wafer at an implantation position. The sample fixing table 5 is driven by a driving mechanism (not shown) to reciprocate (scan) in a vertical direction (a direction perpendicular to the paper surface).

An irradiation mask 2 having an injection opening 2a having a predetermined area is arranged upstream of the sample fixing table 5. The irradiation mask 2 limits the beam irradiation area downstream from the irradiation mask 2. Only the ion beam 1 that has passed through the injection opening 2 a is irradiated on the sample 6 that is held by the sample fixing table 5 and mechanically scanned. It has become so.

The injection opening 2a in the irradiation mask 2
Faraday apertures 2b and 2b on both sides in the beam scanning direction
c is drilled, a dose Faraday 3 described later is provided (downstream) behind the Faraday opening 2b, and a beam scanning area (an overscan is performed as necessary) is provided behind the Faraday opening 2c. Monitor Faraday 4 for confirming whether or not each of them is provided.

Further, a multipoint Faraday 7 in which a number of small Farades 14... (See FIG. 1) as beam collectors are arranged in the beam scanning direction is disposed downstream of the injection position. As shown in FIG. 1, the multi-point Faraday 7 includes a plurality of Farades 14, a multi-point Faraday mask 12 in which a plurality of beam incident holes 12 a. And a suppressor electrode 13 provided near the opening of the Faraday 14. When the sample fixing table 5 reciprocating in the vertical direction is located at a position outside the beam irradiation area (that is, near the lowest or highest position), the scanned ion beam 1 is applied to the multipoint Faraday 7.
Of Farade 14.

The Faraday 14 of the multi-point Faraday 7 is connected to a multi-point Faraday switching relay 11 as switching means. Each multi-point Faraday switching relay 11
One output terminal 11a is connected in parallel and put together into one, connected to one input terminal 8a of the switching relay 8, and the other output terminal 11b is grounded. These multi-point Faraday switching relays 11 are selectively switched under the control of a control device 10 (FIG. 2) described later.

The other input terminal 8b of the switching relay 8
Are connected to the dose Faraday 3 as shown in FIG. The output terminal of the switching relay 8 is connected to a control device 10 via a current integrator (hereinafter referred to as C / I) 9 for integrating the inflow current. The C / I 9 and the controller 10 constitute a beam current detecting means. The switching relay 8 is selectively switched by being controlled by the control device 10.

That is, during the normal dose correction operation (before ion implantation), the control device 10 sets all the multipoint Faraday switching relays 11 to the connected state (ON), and sets the ion beam 1 incident on the Faraday 14. Current is C / I
The input is made by multiplying by 9. Thereafter, the controller 10 switches the beam measurement position by controlling the switching relay 8 so as to be on the dose farad 3 side during the ion implantation operation.

The control device 10 controls the ion beam 1 incident on the dose Farade 3 and the multipoint Farade 7.
The amount of dose to be injected into the sample 6 is converted from the beam current, and the moving speed of the sample fixing table 5 is controlled based on the calculation result so that the amount of injection in the mechanical scan direction is constant. ing. Specifically, if the measured beam current value (dose amount) decreases, the control device 10
The operation of the sample holder 5 is controlled so that the movement speed of the sample holder 5 is decreased in proportion thereto, and conversely, if the beam current value increases, the movement speed is increased in proportion thereto. Thereby, the variation in the ion implantation amount in the vertical direction is reduced.

In the above configuration, an abnormality of the multipoint Faraday 7, such as a break in an electric wire connected to a certain Faraday 14 or a ground fault in a certain Faraday 14, can be detected as follows.

That is, the control device 10 firstly sets the sample fixing table 5 so that the ion beam 1 is incident on the multipoint Faraday 7.
Is removed from the beam irradiation area, the switching relay 8 is switched to the multipoint Faraday 7 side, and the measurement state by the multipoint Faraday 7 is set. At this time, all the multi-point Faraday switching relays 11 are turned off (ground side).

In this state, the control device 10 measures the beam current amount for all the Faraday 14 while sequentially turning on the multipoint Faraday switching relays 11 one by one. The control device 10 determines the presence or absence of an abnormality based on, for example, whether or not the ratio of the measurement values of each Faraday 14 falls within a predetermined range (for example, 1.00 ± 0.01).

In this embodiment, as described above, an abnormality such as a disconnection or a ground fault in the multipoint Faraday 7 can be reliably detected. Therefore, for example, immediately before the injection operation is started, the abnormality detection operation is performed. By confirming the soundness of the multi-point Faraday 7 by performing the correction, the injection dose amount using the multi-point Faraday 7 is accurately corrected.

In this embodiment, one Faraday 14 is connected to one
This is an example in which n Farades 14 are divided into n groups as groups.
n) It may be divided into groups.

Next, as another embodiment of the present invention, a case where 11 Farades 14 are divided into three groups will be described in detail with reference to FIGS. For the sake of convenience, members having the same functions as those shown in the drawings of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 3, the multipoint Faraday 7 of this embodiment has Farade No. 1 to No. 1 in the order of arrangement from one end.
Each of the Farades 14 No. 1, 4, 7, 10 has an A group, and each of the Nos. 2, 5, 8, 11, 11 Are divided into groups B, and Farades 14 of Nos. 3, 6, and 9 are divided into groups C. The Faraday 14 belonging to each of the groups A, B, and C are connected in parallel for each group to be grouped into one, and each is connected to the multipoint Faraday switching relay 11 as switching means.

One output terminal 11a of each multipoint Faraday switching relay 11 is connected in parallel to be combined into one, connected to the switching relay 8 (FIG. 2), and the other output terminal 11b.
Is grounded. Each of the multipoint Faraday switching relays 11 is selectively switched under the control of the control device 10 (FIG. 2).

That is, during the normal dose correction operation, the control device 10 turns on all the multi-point Faraday switching relays 11 to turn on the ion beam 1 incident on all the Faraday 14.
And measure the beam current. On the other hand, when detecting the presence or absence of the abnormality of the multi-point Faraday 7, the multi-point Faraday switching relay 11
Are sequentially turned on one by one, and the beam current amount is measured for each group.

Hereinafter, the operation of detecting an abnormality of the multipoint Faraday 7 by the control device 10 will be described in detail.

First, the controller 10 removes the sample fixing table 5 from the beam irradiation area so that the ion beam 1 is incident on the multipoint Faraday 7, and switches the multipoint Faraday so that only the group A is connected to the C / I9. The relay 11 is controlled. That is, the control device 10 turns on only the multipoint Faraday switching relay 11 connected to the group A, turns off (grounds) the other switching relays 11, and switches the switching relay 8 to the multipoint Faraday 7 side.

In this state, the ion beam 1 is scanned a predetermined number of times by a sweep power supply (not shown). Thereby, the ion beam 1 irradiates the Farade 14 a certain number of times, and the beam current of the ion beam 51 incident on the Farade 14 of the A group becomes C / I as shown in FIG.
9, and the integrated value of the beam current is taken into the control device 10. Here, the beam current integral of the group _A is defined as QA.

Next, the control device 10 switches the multi-point Faraday switching relay 11 and, in the same manner as described above, integrates the beam current of the ion beam 51 incident on the Farades 14 of the B group and the C group (these values are referred to as the integral values). Q _B and Q
_C )).

The control device 10 calculates the integrated beam current value Q _A ·
After Q _B · Q _C is obtained, the ratios, for example, Q _A / Q
_B, Q _C / Q _A, determine the Q _C / Q _B, if the ratio is within the normal range, multipoint Faraday 7 is determined to be normal, if even one normal range, some abnormal Judge that there is. These determination results are displayed on a monitor (not shown), for example.

[0043] More specifically, the normal range of each _{ratio, 0.95 ≦ Q A / Q B} ≦ 1.05 0.70 ≦ Q C / Q A ≦ 0.80 0.70 ≦ Q C / Q _B ≦ 0.80. However, it is not limited to this.

Here, Table 1 below shows Faraday N shown in the table.
6 shows a determination result by the control device 10 when a disconnection occurs in the Faraday 14 of o.

[0045]

[Table 1]

(The asterisks in the table indicate out of the normal range.) As described above, even when several wires are disconnected at the same time, the abnormality determination is reliably performed. When the Faraday 14 has a ground fault, the beam current is C /
Since the flow does not flow to I9, the abnormality determination is performed in the same manner as described above.

As in this embodiment, n Farades 14...
Is divided into m (m <n) groups, it is preferable not to perform division so that all groups have a 1: 1 ratio. This is because, when one Faraday 14 is disconnected in each group, the ratio between the groups remains at 1: 1 and does not change, so that an abnormality may not be detected.

As described in this embodiment, if the adjacent Farades 14 are grouped so as to be in different groups, even if the Farades 14 are in contact with each other, even if an abnormality is detected, Since the adjacent Faraday 14 is grounded, the Faraday 14 on which the measurement is being performed is also in a ground fault state, and an abnormality can be detected.

As in this embodiment, one Faraday 14 ...
Is divided into three groups and anomaly detection is performed.
Where a detection time of 1 second is required, an abnormality can be detected in 3 seconds, and the detection time can be greatly reduced. Further, as compared with the case where the multi-point Faraday switching relay 11 is provided for each Faraday 14, the number of the multi-point Faraday switching relay 11 can be reduced, and the cost can be reduced. That is, by dividing the n Farades 14 into m (m <n) groups, the soundness of the multipoint Faraday 7 can be efficiently confirmed at low cost.

[0050]

As described above, the beam current measuring device of the present invention divides a plurality of beam collectors into a plurality of groups, and connects the divided beam collectors to the beam current detecting means. Switching means for switching connection and disconnection between the two groups, and further based on the beam current value of each group.
Abnormality detection means for detecting the above beam collector abnormality
It is a Eteiru configuration.

Therefore, the beam current value for each group can be measured by sequentially switching the switching means for turning on while irradiating each beam collector with a predetermined beam. It is possible to easily detect an abnormality of the beam collector such as a ground fault and a ground fault. Further, since the number of groups to be divided is small, it is possible to detect an abnormality of the beam collector in a short time.

For example, when a beam current measuring apparatus is provided in an ion implantation apparatus and is used for correcting an implantation dose, the above-described abnormality detection of the beam collector is carried out immediately before the implantation operation is started. Correction of the implantation dose in the middle is performed accurately.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional plan view of a multipoint Faraday showing an embodiment of the present invention and showing a state where a multipoint Faraday switching relay is connected for each Faraday.

FIG. 2 is a schematic configuration diagram showing a main part of an ion implantation apparatus provided with a multipoint Faraday having a multipoint Faraday switching relay.

FIG. 3 shows another embodiment of the present invention, in which a plurality of farads are divided into three groups, and a multipoint farade switching relay is connected for each group; It is sectional drawing.

FIG. 4 shows a conventional example, and is a schematic configuration diagram showing a main part of an ion implantation apparatus provided with a multipoint Faraday.

FIG. 5 is a schematic cross-sectional view showing the multipoint Faraday.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion beam 7 Multi-point Faraday 9 Current integrator (beam current detection means) 10 Controller (beam current detection means) 11 Multi-point Faraday switching relay (switching means) 14 Farade (beam collector)

Claims (1)

(57) [Scope of request for utility model registration] A plurality of beam collectors;
Beam current that detects the beam current of the beam
A beam current measuring device provided with a current detecting means, wherein the plurality of beam collectors are divided into
AndAnd beams included in at least one group
Collectors are set to multiple and  Between the connection between each divided group and beam current detection means
Switching means for switching the connection and disconnection between them is provided.
Re, Furthermore, based on the beam current value of each of the above groups,
Equipped with abnormality detection means for detecting abnormality of the beam collector
ing A beam current measuring device characterized by the above-mentioned.