TECHNICAL FIELD

The present invention relates to a linear motor for driving a sample stage in a vacuum sample chamber.

BACKGROUND ART

In a vacuum processing apparatus, represented by an electron microscope, an ion beam apparatus, a semiconductor manufacturing apparatus, and a semiconductor measurement and inspection apparatus, in which a sample is observed, inspected, measured, analyzed, processed and conveyed (hereinafter referred to as “processing”) in a vacuum space, it is normal to perform various processing on a target sample while moving the sample to be processed by a movable stage. A linear motor is employed as a driving mechanism for realizing high speed movement and high precision positioning of the movable stage used in the vacuum processing apparatus. The linear motor includes a moving magnet type linear motor. The moving magnet type linear motor includes a mover having a permanent magnet and a stator having a coil through which a control current passing, and there is no need for power supply wires to movable portions, so that it suitable for a case where it is desired to reduce a risk of disconnection and foreign matter generation caused by movement of the power supply wires.

PRIOR ART LITERATURE

Patent Literature

PTL 1: JP-A-2014-128177

SUMMARY OF INVENTION

Technical Problem

Meanwhile, the moving magnet type linear motor using the coil as the stator requires a coil whose length corresponds to a movable stroke of a stage. That is, if the stroke is intended to be long, the number of the coils needs to be increased accordingly, and therefore the number of wires to be introduced into a vacuum chamber in an electron microscope tends to increase. The increase in the number of the wires in the vacuum sample chamber leads to problems such as an increase in the number of assembly operations, an increase in cost, and an increase in an amount of outgassing generated from wire coating. In order to solve these problems, PTL 1 discloses a linear motor in which an entire coil on a stator side is covered by a packaging member having a vacuum sealing structure, and a space between a mover having a permanent magnet and a stator having a coil is airtightly separated.

However, in the technology disclosed in PTL 1, since the stator having the coil is disposed in an atmospheric environment, and the mover having the permanent magnet is disposed in a vacuum environment, the packaging member is required to separate the space between the coil and the permanent magnet, and a gap greater than or equal to a thickness of the packaging member is generated between the coil and the permanent magnet. For example, in the vacuum sample chamber of the electron microscope, a high vacuum of 10-5 Pa may be required, and in order to secure a mechanical strength of the packaging member for separating the vacuum environment and the atmospheric environment, a stainless packaging member requires to a thickness of several centimeters. In the linear motor, thrust efficiency decreases as the gap between the coil and the permanent magnet increases, and therefore, when a distance between the stator and the mover is more than several centimeters, there is a problem that thrust generation efficiency of the linear motor is significantly reduced.

The invention is made in view of the above problems, and an object thereof is to provide a linear motor capable of improving the thrust generation efficiency while reducing the amount of the outgassing generated from wire coating and the number of assembly operations of the linear motor.

Solution to Problem

In order to the above problems, a linear motor for vacuum is provided, the linear motor for vacuum including: a mover having a permanent magnet; and a stator having a support member to which a coil is fixed, in which the support member includes a vacuum sealing portion that vacuum seals with a wall surface of a vacuum sample chamber, and a feed-through for supplying a current to the coil provided in the vacuum sample chamber.

A linear motor for vacuum is further provided, the linear motor for vacuum including: a mover having a permanent magnet; and a stator having a coil covered by a resin member, in which the stator includes a support member having a vacuum sealing portion that vacuum seals with a wall surface of a vacuum sample chamber and a first through hole portion, and a wire for supplying a current to the coil provided in the vacuum sample chamber. The wire is led out to an outside of the vacuum sample chamber through the first through hole portion. The first through hole portion is filled with the resin member integrally or with a filler that binds to the resin member, so that the through hole portion is sealed.

Further, a vacuum processing apparatus including a linear motor for vacuum is provided. The linear motor for vacuum includes a mover having a permanent magnet, a stator having a coil covered by a resin member, and a wire for supplying a current to the coil provided in a vacuum sample chamber. The wire is led out to an outside of the vacuum sample chamber through a through hole portion provided in the wall surface of the vacuum sample chamber. The through hole portion is filled with the resin member integrally or with a filler that binds to the resin member, that the through hole portion is sealed.

Advantageous Effect

According to the above configuration, it is possible to implement a linear motor capable of preventing outgassing generated from wire coating in a vacuum sample chamber, and having excellent assembly operation efficiency and maintainability and high thrust generation efficiency, and a vacuum processing apparatus using the linear motor.

