JP3713862B2 - Multipoint Faraday equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used in, for example, an ion implantation apparatus, an ion beam irradiation apparatus, an electron beam irradiation apparatus, an electron microscope, and the like, and more specifically for measurement of a charged particle beam such as an ion beam or an electron beam that is electromagnetically scanned. In particular, the present invention relates to a multi-point Faraday apparatus used for measurement of a scanning position of a charged particle beam, measurement of parallelism of a charged particle beam based on this measurement, measurement of uniformity of scanning speed, and the like.
[0002]
[Prior art]
As a typical example of using a charged particle beam to be scanned, there is an ion implantation apparatus that irradiates a target with a scanned ion beam and performs ion implantation on the target. Hereinafter, an ion implantation apparatus will be described as an example.
[0003]
FIG. 3 is a perspective view partially showing the periphery of a target of an ion implantation apparatus having two conventional multipoint Faraday. In this ion implantation apparatus, a spot-like ion beam 2 is electromagnetically scanned by a scanning means (not shown) (that is, by an electric field or a magnetic field) in the X direction (for example, the horizontal direction, the same applies hereinafter) in parallel (parallel scan). A parallel beam parallel to the Z direction orthogonal to the direction is obtained, and the target (for example, a semiconductor wafer) 4 is machined in a Y direction (for example, the vertical direction; the same applies hereinafter) substantially orthogonal to the X direction by a driving device (not shown). The target 4 is uniformly irradiated with the ion beam 2 by the cooperation of the electromagnetic scan of the ion beam 2 and the mechanical scan of the target 4 (hybrid scan). The ion implantation is performed uniformly.
[0004]
Conventionally, in such an ion implantation apparatus, the parallelism measurement of the ion beam 2, the prediction of the uniformity of implantation on the target 4, the shaping of the scanning signal for scanning the ion beam 2, and the like have been conventionally performed, for example, in Japanese Patent Laid-Open No. 4-22900. As described also in FIG. 2, it is arranged on the upstream side and the downstream side with respect to the traveling direction of the ion beam 2, more specifically, in this example, it is arranged on the upstream side and the downstream side with the target 4 interposed therebetween. Two multi-point Faraday 10 and 20 were used.
[0005]
Each multi-point Faraday 10 and 20 has a plurality of Faraday cups 12 and 22 that receive the ion beam 2 and measure the beam current, respectively, arranged in the X direction that is the scanning direction of the ion beam 2, and preferably They are arranged at intervals. The position of each Faraday cup 12, 22 in the X direction is known in advance.
[0006]
In the example of FIG. 3, the upstream multipoint Faraday 10 is attached to the front portion of the support plate 14 having the opening 16, and is moved up and down with respect to the beam trajectory as indicated by an arrow A by the arm 18. It is done. That is, the multipoint Faraday 10 is lowered as indicated by a two-dot chain line during beam current measurement, and the ion beam 2 is allowed to pass rearward through the opening 16 and enter the target 4 or enter the multipoint Faraday 20. When it is done, it is raised as shown by the solid line. The multipoint Faraday 20 on the downstream side is fixed, and when the ion beam 2 is incident thereon, the target 4 is retracted to a position where it does not block the ion beam 2 (for example, below).
[0007]
A method for measuring the parallelism of the ion beam 2 using the two multipoint Faradays 10 and 20, predicting the uniformity of implantation, and shaping the scanning waveform is described in detail in the above-mentioned JP-A-4-22900. However, it can be summarized as follows.
[0008]
(1) Parallelism measurement {circle around (1)} First, at least one reciprocal scan is performed with the ion beam 2 incident on the upstream multipoint Faraday 10 and the downstream multipoint Faraday 20.
[0009]
(2) At this time, the beam current of the incident ion beam 2 to both the multipoint Faraday 10 and 20 is sampled by using a data logger or the like, and the data representing the temporal change of the beam current is obtained as the data of the both multipoint Faraday 10. , 20 respectively. In addition, the downstream data has a plurality of peaks corresponding to the state in which the ion beam 2 is incident on the centers of the plurality of Faraday cups 12 and 22 constituting the multipoint Faraday 10 and 20.
[0010]
(3) Continuous temporal change in the scanning position of the ion beam 2 by performing appropriate interpolation and extrapolation on the data representing the relationship between the discrete position and time of the ion beam 2 thus obtained. Are obtained for the upstream multipoint Faraday 10 and the downstream multipoint Faraday 20 respectively.
[0011]
(4) From the above two functions (that is, the upstream side and the downstream side), referring to FIG. 4, the scanning position X _f (multi-point Faraday 10 on the upstream side of the ion beam 2 at the time t corresponding to each other at the time t. t) and the scanning position X _b (t) at the downstream multi-point Faraday 20 are obtained, and the parallelism θ (t) of the ion beam 2 at time t can be obtained from the following equation based on the positional relationship between the two. . L is the distance between the two multipoint Faraday 10 and 20. Then, by changing this noticed time t, the parallelism of a plurality of points in the scanning region of the ion beam 2 can be determined in detail.
[0012]
[Expression 1]
θ (t) = tan ⁻¹ {(X _f (t) −X _b (t)) / L}
[0013]
(2) Prediction of implantation uniformity (1) First, the upstream side of the ion beam 2 is subjected to the same procedure as the above (1) (1) to (4) described in the case of measuring the parallelism of the ion beam 2. Scan positions as a function of continuous time are determined for the multipoint Faraday 10 and the downstream multipoint Faraday 20.
[0014]
(2) Next, the scanning position of the ion beam 2 at the time t on the target 4 is obtained by the positional relationship between the multipoint Faraday 10 and 20 and the target 4 and the function obtained in (1) above. That is, referring to FIG. 5, when the distances between the target 4 and the multipoint Faraday 10 and 20 are L ₁ and L ₂ , respectively, the scanning position X _f (t ) and from the scanning position on the multipoint Faraday 20 X _b (t), the scan position of the ion beam 2 on target 4 X _t (t) is determined by the following equation.
[0015]
[Expression 2]
_{X t (t) = (L} 2 X f (t) + L 1 X b (t)) / (L 1 + L 2)
[0016]
(3) The scanning speed of the ion beam 2 on the target 4 is dX _t (t) / dt, and the implantation uniformity on the target 4 is such that the beam current density of the ion beam 2 does not change depending on the scanning position. In this case, since the reciprocal of this scanning speed is {dX _t (t) / dt} ^−1, it is possible to predict the injection uniformity on the target 4.
[0017]
(3) scanning waveform shaping which is the so the scanning rate is small at the scanning rate dX _t (t) / dt of the ion beam 2 obtained in (2) is large, conversely dX _t (t) / The slope of the scanning waveform of the ion beam 2, for example, the scanning voltage waveform of the ion beam 2, is decreased (when the scanning speed is decreased) or increased (scanning) so that the scanning speed increases at a small dt. This is a method in which the scanning speed dX _t (t) / dt of the ion beam 2 on the target 4 is made to be constant by increasing the speed).
[0018]
[Problems to be solved by the invention]
However, conventionally, since the two multipoint Faraday 10 and 20 were used, there were the following problems.
[0019]
{Circle around (1)} Each multipoint Faraday 10 and 20 is composed of a plurality of Faraday cups 12 and 22 arranged side by side, so that the number of parts is large and the number of assembly steps is large and expensive. Therefore, if two such expensive multipoint Faraday are used, an ion implantation apparatus etc. will become expensive.
[0020]
(2) The function of each multipoint Faraday 10 and 20 deteriorates due to contamination caused by ion beam irradiation, etc., and therefore it is necessary to perform maintenance work regularly. Work increases and maintenance costs increase.
[0021]
(3) Since two sets of circuits for processing the signals received from the multipoint Faraday 10 and 20 are required, the cost of the signal processing circuit also increases.
[0022]
As long as two multi-point Faraday are used, the above-mentioned problem exists similarly in the measurement of charged particle beams other than the ion implantation apparatus as described above or other than the ion beam.
[0023]
Therefore, the main object of the present invention is to provide a multi-point Faraday apparatus that can perform the same measurement as that using at least two conventional multi-point Faraday using one multi-point Faraday.
[0024]
[Means for Solving the Problems]
Multipoint Faraday device of the present invention, while being scanned by a device used to measure the charged particle beam that will be emitted to the target, a plurality of Faraday cups for receiving the charged particle beam is said scanning each of said charged particle beam a multipoint Faraday made side by side along the scanning direction, the multipoint Faraday, is moved back and forth along the traveling direction of the charged particle beam, at least before and after the Ru is positioned by the respective one location drives sandwiching the target It is characterized by having.
[0025]
According to the above arrangement, a single multipoint Faraday, by the drive device, is moved back and forth along the traveling direction of the charged particle beam, since it is Rukoto is positioned by the respective one place at least before and after sandwiching the target, Using one multi-point Faraday, it is possible to measure a charged particle beam at least at one place before and after the target . Therefore, at least the same measurement as when two conventional multi-point Faradays are used can be performed.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a plan view showing an example in which the multipoint Faraday apparatus according to the present invention is used in an ion implantation apparatus. The ion beam 2 and the target 4 are as described above, and a duplicate description thereof is omitted here.
[0027]
The multi-point Faraday device 30 includes a plurality of Faraday cups 34 that receive a charged particle beam to be scanned, specifically, an ion beam 2 that is scanned in parallel in the X direction as described above, and measure the beam current. As indicated by an arrow B, a multipoint Faraday 32 that is arranged along the scanning direction X of the ion beam 2 (in other words, orthogonal to the traveling direction Z of the ion beam 2), and the multipoint Faraday 32, as shown by an arrow B, And a driving device 40 that moves forward and backward along the traveling direction Z of the ion beam 2. Reference numeral 38 denotes the drive shaft.
[0028]
In this example, the Faraday cups 34 of the multipoint Faraday 32 are supported by a support plate 36 while being electrically insulated from each other. The position of each Faraday cup 34 in the X direction is known in advance. The Faraday cups 34 are preferably arranged at equal intervals along the X direction, so that the ion beam 2 can be measured uniformly in the X direction.
[0029]
The drive device 40 includes, for example, a pneumatic cylinder, a hydraulic cylinder, or a combination of a motor and a ball screw that converts the rotation into linear motion.
[0030]
The position where the multipoint Faraday 32 is moved back and forth along the beam traveling direction Z by the driving device 40 is, for example, two positions, but may of course be three or more positions. Specifically in this example, the multipoint Faraday 32, the driving device 40 is moved to the second position between the position Z _b position Z _f and the downstream side of the upstream side across the target 4.
[0031]
Normally, so as not to interfere with processing of the target 4, keep the multipoint Faraday 32 is positioned at a position Z _b of the downstream side. This corresponds to, for example, the position of the multipoint Faraday 20 on the downstream side of the conventional example shown in FIG. When this multipoint Faraday device 30 is used for measuring the parallelism of the ion beam 2 as described above, predicting the uniformity of implantation on the target 4, shaping the scanning waveform such as the scanning voltage, etc. After measurement of the ion beam 2 at the position Z _b (more specifically, measurement of the peak position of the ion beam 2 at each Faraday cup 34), the multipoint Faraday 32 is advanced by the drive device 40 to move upstream. It is located at position Z _f. At that time, the target 4 may be moved in the Y direction (specifically, downward) by the drive device described above and retracted to a position where it does not interfere with the multipoint Faraday 32 and the drive shaft 38. The upstream position _Zf corresponds to, for example, the position of the upstream multipoint Faraday 10 of the conventional example shown in FIG. And even at the position Z _f of the upstream side, to measure the ion beam 2 in the same manner as in the position Z _b of the downstream side. The data processing method after the measurement at these two positions Z _f and Z _b is the same as in the case of the conventional example.
[0032]
Although the position Z _f on the upstream side of the multipoint Faraday 32 is preferably a position upstream of the target 4 for measuring the parallelism of the ion beam 2 described above, the surface position Z of the target 4 is preferred. It may be substantially equal to _t (including equal). By doing so, for example, the measurement of the beam current density distribution in the scanning direction X of the ion beam 2 incident on the surface of the target 4 and the measurement of the uniformity of implantation on the target 4 can be performed at the implantation position with respect to the target 4. Can be measured.
[0033]
That is, the position Z _f of the multipoint Faraday 32 is made substantially equal to the surface position Z _t of the target 4, the ion beam 2 is scanned in the X direction, and the ion beam 2 is moved to a plurality of Faraday of the multipoint Faraday 32. The beam current density distribution in the scanning direction X of the ion beam 2 as shown in FIG. 2, for example, can be measured by measuring the beam current density received by the cup 34 and flowing through each Faraday cup 34. This beam current density distribution also represents the uniformity of implantation on the target 4. Note that 1 to n in FIG. 2 are the numbers of the Faraday cups 34.
[0034]
As described above, according to the multipoint Faraday device 30, one multipoint Faraday 32 can be moved back and forth along the traveling direction Z of the ion beam 2 by the driving device 40. Using the Faraday 32, the ion beam 2 can be measured at a plurality of locations. Therefore, at least the same measurement as in the case of using the conventional two multipoint Faraday 10 and 20 can be performed.
[0035]
Moreover, since only one multipoint Faraday 32 is required and the driving device 40 is generally lower in cost than the multipoint Faraday, the cost can be reduced compared to the case where two multipoint Faraday are used as in the prior art. It is possible to reduce the maintenance cost because one multipoint Faraday maintenance work is reduced. Furthermore, since only one signal processing circuit for multipoint Faraday is required, the cost can be reduced in this sense.
[0036]
The multi-point Faraday device 30 is a measurement of an ion beam in an ion implantation device other than the ion implantation device as in the above example, an ion beam irradiation device that irradiates a target with an ion beam, and an electron beam irradiation device or an electron. Of course, it can also be used for measuring an electron beam in a microscope.
[0037]
【The invention's effect】
According to the invention, as described above, a single multipoint Faraday, by the drive device, is moved back and forth along the traveling direction of the charged particle beam, is positioned by the respective one place at least before and after sandwiching the target Rukoto Therefore, using one multi-point Faraday, it is possible to measure a charged particle beam at least at one place before and after the target . Therefore, at least the same measurement as when using two conventional multi-point Faraday can be performed.
[0038]
Moreover, since only one multipoint Faraday is required and the drive device is generally lower in cost than the multipoint Faraday, the cost can be reduced compared to the case where two multipoint Faraday are used as in the prior art. In addition, the maintenance work for the multi-point Faraday is reduced by one, so the maintenance cost is also reduced. Furthermore, since only one signal processing circuit for multipoint Faraday is required, the cost can be reduced in this sense.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example in which a multipoint Faraday device according to the present invention is used in an ion implantation device.
FIG. 2 is a diagram showing an example of a beam current density distribution of an ion beam.
FIG. 3 is a perspective view partially showing the periphery of a target of an ion implantation apparatus having two conventional multipoint Faraday.
FIG. 4 is a diagram showing an example of a relationship between scanning positions of ion beams on an upstream multipoint Faraday and a downstream multipoint Faraday.
FIG. 5 is a diagram illustrating an example of a relationship between scanning positions of ion beams on an upstream multipoint Faraday, a downstream multipoint Faraday, and a target.
[Explanation of symbols]
2 Ion beam (charged particle beam)
4 Target 30 Multipoint Faraday Device 32 Multipoint Faraday 34 Faraday Cup 40 Drive Device

Claims (1)

While being scanned by a device used to measure the charged particle beam that will be irradiated to the target, multipoint comprising a plurality of Faraday cups for receiving a charged particle beam to be the scanned respectively side by side along the scanning direction of the charged particle beam a Faraday, the multipoint Faraday, is moved back and forth along the traveling direction of the charged particle beam, multi-point, characterized in that it comprises at least the front and rear Ru is positioned by the respective one location drives sandwiching the target Faraday equipment.

Images