JPH0617103U - Vacuum exhaust system for low energy ion gun - Google Patents

Abstract

(57) [Abstract] [Purpose] To make the vacuum exhaust system of an ion gun compact. [Structure] The low energy ion gun I includes, for example, an ion source unit 1, a lens unit 2, a deflection unit 3, a mass separation unit 4, and a deceleration unit 5.
And the speed reducer is coupled to the target chamber 6. A first vacuum pump 8 is connected to the target chamber, and the inside of the chamber and the ion gun are evacuated. A second vacuum pump 10 and a conductance valve 13 are connected between the beam upstream portion of the ion gun, the lens portion 2 and the beam downstream portion, and the deceleration portion. Run the first vacuum pump,
Then, the second vacuum pump is activated. Until the pump reaches a normal rotation speed, the degree of vacuum in the exhaust passage of the second vacuum pump is monitored by the vacuum gauge 14 and the opening of the conductance valve is adjusted so as to gradually increase.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vacuum exhaust device for a low energy ion gun having a simple vacuum exhaust system.

[0002]

[Prior art]

 An ion gun is attached to the molecular beam epitaxy (MBE) device, and the development of a composite technology for forming films by simultaneously injecting ions such as oxygen and silicon with the ion gun while flying the molecular beam from the molecular beam cell to the sample There is. However, compared with a mere gas or neutral beam, the one using an ion beam has excellent adhesiveness and has the property and advantage that it is easy to control. Since such an ion gun is installed in parallel with the molecular beam cell in the growth chamber of the MBE apparatus, it is configured as a miniaturized ion implantation apparatus used in an ordinary semiconductor manufacturing apparatus.

FIG. 3 is a configuration diagram of a low energy ion gun which is disclosed in a separate application and which can be used as one component of the MBE apparatus. The ion gun I generally includes an ion source unit 1, a lens unit 2 including an Einzel lens, a deflecting unit 3 including an XY electrostatic deflection plate, a mass separation unit 4 including a Wien filter, and an Einzel lens integrated deceleration system. It is composed of a speed reducer 5 made of a pipe. By using the Wien filter for mass separation and integrating the deceleration tube with the Einzel lens, the entire ion gun can be made linear and compact, and the target can be irradiated with a well-focused ion beam. It is possible. Moreover, it flange 1 ₁ of the ion source portion 1, the lens unit chamber 2 _first flange 2 _2, deflection unit chamber 3 ₁ of flange 3 _2, mass separation unit chamber 4 _first flange 4 _2, the speed reduction unit chamber 5 _first flange 5 ₂ has assumed and is formed at the same size, which depending on the application, can be combined arbitrarily set the respective functional components of the ion gun I.

FIG. 2 shows a configuration diagram of a vacuum exhaust system in an ion implantation apparatus using the ion gun I. The deceleration unit 5 of the low-energy ion gun I is connected to a target chamber 6 that accommodates a target into which ions are implanted, and the ion source unit 1 is biased to a positive potential of, for example, several 10 to 300 V with respect to a ground point. The lens unit 2, the deflection unit 3, the mass separation unit 4, and the deceleration unit 5 have a high negative potential of about 10 kV with respect to the ion source unit 1. The ion beam from the ion source unit 1 is injected through the high potential portion of the ion gun into the target in the target chamber 6 at the ground potential at an energy of several tens to 300 V. An insulating section 7 is provided in the lens chamber 2 ₁ and the deceleration chamber 5 ₁ to insulate the high potential portion of the ion gun.

The interior of the target chamber 6 and the ion gun I is evacuated by a vacuum pump 8 connected to the target chamber, but the Einzel lens unit 2 and the deflecting unit 3 have a vacuum degree due to the gas from the ion source unit 1. Getting worse. When the degree of vacuum is in the 10 ^-4 Torr range, the ion beam extracted from the ion source 1 diverges greatly and the ion beam is neutralized, and the amount of beam current given to the target decreases. . A vacuum pump and a turbo molecular pump 10 are connected to the Einzel lens chamber 2 ₁ at a high electric potential therethrough via an insulated exhaust pipe 9. Is connected to the rotary pump 12.

[0006]

[Problems to be solved by the device]

In this way, by evacuating the lens unit chamber 2 in ₁ with the turbo molecular pump 10, keeping the inside the chamber level of 10 ^-5 Torr, ion beam - is leading arm to efficiently target. However, according to such a vacuum exhaust system, since the vacuum exhaust must be performed through the insulating exhaust pipe 9, the exhaust conductance becomes small and the vacuum exhaust efficiency becomes poor. Further, since the roughing rotary pump 12 and the exhaust passage pipe 13 are required, the vacuum exhaust system becomes large for a small ion gun, and the entire system becomes large.

An object of the present invention is to provide a vacuum exhaust device for a low energy ion gun, which can make the entire system compact without impairing the degree of vacuum after the ion source.

[0008]

[Means for Solving the Problems]

 The present invention is a vacuum pumping apparatus for a low energy ion gun that supplies an ion beam to a target chamber to which a first vacuum pump is connected, and is connected between the beam upstream and downstream of the ion gun. It is characterized by comprising a second vacuum pump and a conductance valve provided in the exhaust passage on the beam downstream side of the second vacuum pump.

[0009]

[Action]

The first vacuum pump is operated to evacuate the target chamber and the entire ion gun. After that, operate the second vacuum pump and operate the opening of the conductance valve until the speed of the pump reaches the normal speed so that the vacuum degree of the exhaust path becomes 10 ^-2 to 10 ^-3 Torr. Adjust to. The degree of vacuum at the upstream portion of the beam of the ion source connected to the suction passage of the second vacuum pump is on the order of 10 ^-5 Torr.

[0010]

【Example】

An embodiment of the present invention will be described with reference to the block diagram of FIG. The same reference numerals as those in FIGS. 2 and 3 denote the same parts. A first vacuum pump 8 is connected to the target chamber 6 to evacuate the chamber and the ion gun I as a whole. The intake path of the turbo molecular pump 10, which is the second vacuum pump, is connected to the beam upstream part of the ion gun, and the chamber 2 ₁ of the lens part 2, and the exhaust path of the pump is connected to the ion valve via the conductance valve 13. It is connected to the chamber 5 ₁ of the speed reducer 5 at the downstream side of the gun beam.

By operating the first vacuum pump 8, the inside of the target chamber 6 and the ion gun I is evacuated, and the required vacuum degree is maintained. Then, the turbo molecular pump 10, which is the second vacuum pump, is started. Initially, the conductance valve 13 is closed, and the degree of vacuum in the exhaust passage of the turbo molecular pump is set to a thermocouple vacuum gauge or a Pirani vacuum gauge until the rotation speed of the turbo molecular pump 10 reaches a normal rotation speed. It monitors it with 14, and adjusts it so that the degree of vacuum may become 10 ^-2 to 10 ^-3 and the opening of the valve is increased. Along with this, without disturbing the operating state of the first vacuum pump 8, the vacuum degree of the lens section 2 or the deflecting section 3 of the ion gun finally reaches the level of 10 ⁻⁵ Torr, and this state is maintained. Can be kept.

[0012]

[Effect of device]

 Since the present invention is configured as described above, since the second vacuum pump system can be arranged in the high potential part, the insulating exhaust pipe is not used and the exhaust efficiency can be improved. Further, since the rotary pump for roughing and the exhaust system for the second vacuum pump, which are required in the conventional apparatus, are not required, the vacuum exhaust system can be simplified and the entire system can be made compact.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional vacuum exhaust system.

FIG. 3 is a schematic configuration diagram of a low energy ion gun.

[Explanation of symbols]

 I Ion gun 1 Ion source part 2 Lens part 3 Deflection part 4 Mass separation part 5 Deceleration part 6 Target chamber 8 First vacuum pump 10 Second vacuum pump 13 Conductance valve 14 Vacuum gauge

Claims (1)

[Scope of utility model registration request] 1. An ion gun for supplying an ion beam to a target chamber to which a first vacuum pump is connected, and a second vacuum pump connected between a beam upstream part and a downstream part of the ion gun, A vacuum exhaust device for a low energy ion gun, comprising: a conductance valve provided in a beam downstream side exhaust passage of the second vacuum pump.