JPS62128500A - Charged beam apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a charged beam device, in particular, to accelerate and stack a charged beam such as an electron beam, and to generate synchrotron radiation from an uneven portion of the charged beam. This relates to a charged beam device that utilizes synchrotron radiation (also called synchrotron radiation).

[Conventional technology]

FIG. 4 is a plan view showing a conventional charged beam device. 1
2 is a charged beam accelerating injector which has the function of accelerating a charged beam to a predetermined energy and then injecting the charged beam into a charged beam storage ring, which will be described later. A charged beam transport section 3 provided for transporting the charged beam to and from the beam storage ring is a charged beam storage ring that stores a charged beam of a predetermined energy for a long time and utilizes the synchrotron radiation 9. This charged beam storage ring 3 includes a synchrotron radiation beam (the beam here is a photon beam) 4 for guiding synchrotron radiation to the outside, a deflection electromagnet 6 for deflecting the charged beam to generate synchrotron radiation 9, and In order to keep rotating the charged beam for a long time, there is a vacuum donut 7 that maintains a vacuum level of, for example, about 10' Torr. 8 in the figure indicates the balanced trajectory of the charged beam, and it is known that the synchrotron radiation 9 is emitted from the curved portion of the balanced trajectory 8 of the charged beam in the tangential direction thereof. Further, 10 is a high frequency cavity. In addition, there are a vacuum evacuation device, an electromagnet for adjusting the gL path, etc., which are not shown, but only the parts related to the present invention are shown.

Although only two synchrotron radiation beam lines 4 are shown in the figure, there are usually a plurality of synchrotron radiation beam lines 4 from each deflection section. As the charged beam accelerating injector 1 described above, a linear accelerator, a synchrotron, or the like is usually used. The operation of a conventional device of this type will be explained in detail below.

A charged beam accelerated to a predetermined energy (here E) by a charged beam accelerating injector 1 is incident on a charged beam storage ring 3 via a vacuum beam transport section 2.
After that, it continues to rotate in the equilibrium orbit 8 while keeping the energy E. However, since the charged beam emits synchrotron radiation 9 every time it is deflected, energy loss occurs due to the radiation loss.

This is compensated for by the high frequency cavity 10 shown in the figure, and a predetermined energy is maintained. Furthermore, it is important that the number of charged particles rotating in the charged beam storage ring 3 decreases over time. The mechanism is as follows.

Inside the vacuum donut 7, which is evacuated to a high vacuum,
Although it is a high vacuum, there are some residual molecules. Therefore, the residual molecules and the charged beam collide and are scattered, colliding with the wall surface of the vacuum donut 7, and the charged beam, that is, the group of charged particles, gradually decreases with time. In addition, it is known that the number of particles in a charged beam decreases with a certain probability. In fact, in conventional devices, the charged beam typically diminishes over a lifetime of a few hours. Note that lifetime is defined as the time it takes for the number of charged particles contained in a charged beam to decrease to 1/2 or 36.8% (1/e) of the original number of particles. Common. When expressing the number of charged particles, the current value of the charged beam (herein expressed as Ib) is often used. When the speed of the charged beam is sufficiently close to the speed of light (this condition holds in a normal charged beam device for utilizing synchrotron radiation), the current value 1b of the charged beam and the number N of charged particles are proportional.

lb-f-g-N (11 where g is the charge of one charged particle, and f is the rotation frequency of the charged particle within the ring.

In other words, to summarize what has been explained here, the energy of the charged beam in the charged particle storage ring 3 does not change over time, but the current value of the charged beam decreases over time. be.

Now, the intensity of synchrotron radiation will be explained here.

The intensity of the synchrotron radiation is determined by the energy E of the charged beam and the current value 1b of the charged beam P, as shown in the document "The Favorite of the Next Generation Lithography Technology", Nobushi Atou 5 Magazine Japanese Science and Technology 84. ; α・E −1b・・・・・・
・It can be expressed as (2). Here, P is the intensity or total power of the emitted light, and α is a constant determined by the shape of the charged beam.

Therefore, the intensity of the emitted light decreases over time.

In other words, the amount of synchrotron radiation decreases over time,
It is inconvenient to use.

[Problem that the invention seeks to solve]

In the conventional charged beam device described above, the charged beam N
The intensity or amount of radiation emitted from the charged beam incident on the ring decreases with time, which is inconvenient for use. Further, the number of synchrotron radiation beam lines that can be effectively utilized per one device is limited by constraints from the spatial dimension of the port for the synchrotron radiation beam line from the vacuum donut. Therefore, it is natural to consider increasing the number of synchrotron radiation beam lines that can be used by equipping one charged beam accelerating injector with several charged beam storage rings, but the biggest problem in this case is that each charged beam The problem is that the intensity or amount of light emitted from the beam storage ring differs from each other, which causes problems in use. In other words, the intensity or amount of synchrotron radiation obtained from multiple synchrotron radiation beam lines arranged in a single charged beam storage ring is the same, but the intensity of synchrotron radiation varies between different charged beam storage rings. This is the problem. The reason for this is that even if the charged beam storage rings are designed and manufactured identically and the same evacuation equipment is installed, the rate of detachment of the adsorbed gas from the vacuum donut will vary depending on the conditions during the grinding gas processing at the material stage (e.g. Based on subtle differences in baking temperature and atmosphere) and variations in materials,
There are some differences. Furthermore, due to slight differences in finishing accuracy of bending electromagnets and orbit adjustment electromagnets, variations in current values, and installation errors, the temporal changes in the current value of the charged beam may differ for each charged particle storage ring. To become.

This invention was made in order to solve the above-mentioned conventional problems, and it is possible to obtain a sufficient number of synchrotron beam lines that can be used effectively, and to ensure that the intensity of the synchrotron radiation is almost constant, and that each charge The purpose of this invention is to obtain a charged beam device that can obtain uniform light intensity in a particle storage ring.

[Means for solving problems]

A charged beam device according to the present invention includes a single charged beam accelerating injector and a charged beam transport unit, a plurality of charged beam storage rings, and a light amount monitor of synchrotron radiation or a current monitor of the accumulated charged beam, The charged beam is sequentially transferred from the charged beam accelerating injector to the charged beam transport section so that the amount of synchrotron radiation generated from each charged beam storage ring is constant at a predetermined value according to the value monitored by the monitor or current monitor. The charged beam storage ring is replenished via the charged beam storage ring.

[Effect]

In the present invention, with the above configuration, the amount of emitted light is controlled to be constant at a predetermined value, and the properties and amount of usable emitted light can be significantly improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a charged beam device according to an embodiment of the present invention, and this embodiment shows a case in which two (11) charged beam storage rings 3 are provided.

Reference numeral 5 denotes a synchrotron radiation light amount monitor attached to the synchrotron radiation beam line 4 of each charged beam storage ring 3. Further, 13 receives a signal proportional to the light amount from the light amount monitor 5 of each charged beam storage ring 3, and generates and sends a control signal to the charged beam accelerating injector 1 so that the signal becomes a predetermined light amount. This is the control unit. Further, reference numeral 11 is for switching between a plurality of charged beam branching ports provided in the middle of the charged beam transport section 2. As the light amount monitor 5, a photoelectric conversion type such as a photodiode is well known. In the present invention, there are no particular conditions for the characteristics of this light amount monitor, and it is sufficient to simply be able to grasp the relative value of the light amount. In addition, the control unit 6 is of analog type,
Any digital type is possible, and any type having a general feedback type control function is sufficient.

Next, the operation will be explained using FIG. 2.

In FIG. 2, the horizontal axis is time, and the vertical axis is the charged beam current value in a certain charged beam storage ring 3.

Point A is a beam calculator value (indicated as 0) corresponding to a predetermined light amount value. The beam current value gradually decreases with time from point A, and the amount of light also decreases in proportion to it. The progress of this decrease is monitored by the control unit 6 based on a signal from the light amount monitor 5.
For example, when the value reaches a certain set value (denoted as Iz), the controller 6 controls the charged beam accelerating injector 1 and the charged beam distribution electromagnet 1 to set the required storage ring 3. An operation command for replenishing the charged beam is sent to the charged beam accelerating injector 1, and the charged beam is supplied from the charged beam accelerating injector 1. As a result, the currently targeted charged beam 11
The beam calculator value in the JI ring 3 returns to IO, and therefore the light amount also becomes a predetermined value. By continuously performing this operation, the amount of emitted light can always be kept within a certain set range from a constant value. By performing this operation for each of the plurality of charged beam storage rings, the amount of synchrotron radiation from each charged beam storage ring can be kept within a certain set range, and problems in using synchrotron radiation can be solved. It disappears.

In the above embodiment, a method was explained in which the charged beam is replenished when a certain set value (■1) is reached. Even with the method of replenishing the charged beam current value corresponding to
The effect is similar.

In addition, in the above embodiment, a light amount monitor was used to control the light amount to a predetermined light amount, but instead of using the light amount monitor, the charged beam current value was indirectly measured as shown in FIG. It is also possible to use a current monitor 2. In this case, compared to the above embodiment, there is no need to use one synchrotron radiation beam line for monitoring, and there is an advantage in terms of the utilization rate of synchrotron radiation. A DC current transformer type is generally used as the current monitor 12, but the type is not particularly limited, and any type of type may be used as long as only the beam current can be monitored with high accuracy.

In the above embodiment, the case where the number of charged beam MMi rings is two has been described, but it goes without saying that the same holds true for a larger number of charged beam MMi rings.

〔Effect of the invention〕

As described above, according to the present invention, one charged beam accelerating injector and charged beam transport unit are combined with a plurality of charged beam storage rings, and the amount of synchrotron radiation is observed on a monitor, and by feedback control. Since it is configured to control the amount of synchrotron radiation to be constant at a predetermined value, it has the effect of greatly improving the properties and amount of usable synchrotron radiation.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a characteristic diagram for explaining the operation of the above embodiment, FIG. 3 is a plan view showing another embodiment of the invention, and FIG. The figure is a plan view showing a conventional device of this type. 1 is a charged beam accelerating injector, 2 is a charged beam transport unit, 3 is a charged beam accelerating injector;
is a charged beam storage ring, 4 is a synchrotron radiation beam line, and 5 is a synchrotron radiation beam line.
1 is a synchrotron radiation light amount monitor, 6 is a bending electromagnet, 7 is a vacuum donut, 8 is an equilibrium orbit of a charged beam, 9 is a synchrotron radiation beam, 10 is a high frequency cavity, 11 is a beam distribution electromagnet, 12 is a current monitor, and 13 is a control unit It is. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A single charged beam accelerating injector that generates and outputs a charged beam; a single charged beam transport unit that transports the charged beam from the accelerating injector; and a single charged beam transport unit that is connected to the charged beam transport unit via a branching means. a plurality of charged beam storage rings; a plurality of light intensity monitors for observing the amount of light emitted from each of the charged beam storage rings; a control unit that controls the operation of the charged beam accelerating injector and the branching means so that the amount of radiation light is constant at a predetermined value; A charged beam device characterized in that a charged beam storage ring is supplied via the charged beam storage ring. (2) a single charged beam accelerating injector that generates and outputs a charged beam; a single charged beam transport section that transports the charged beam from the accelerating injector; and a charged beam transport section connected to the charged beam transport section via a branching means. a plurality of charged beam storage rings, a plurality of current monitors that monitor the current value accumulated in each of the charged beam storage rings, and radiation generated from the charged beam storage ring according to the value of the amount of light monitored by the current monitors. and a control section that controls the operation of the charged beam accelerating injector and the branching means so that the amount of light is constant at a predetermined value, and sequentially transports the charged beam from the charged beam accelerating injector via the charged beam transport section. A charged beam device characterized in that a charged beam storage ring is supplied with the charged beam.