JPH0828198B2 - Ion beam device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A. Industrial fields of use B. Overview of the invention C. Prior art [Figs. 2 and 3] D. Problems to be solved by the invention E. Means for solving the problems F. Action G. Example [FIG. 1] H. Effect of the invention (A. Field of industrial application) The present invention relates to an ion beam apparatus, and in particular, an ion beam is emitted from the emitter surface by applying a high voltage between the emitter and the extraction electrode. The present invention relates to an ion beam device to generate.

(B. Summary of the Invention) The present invention is an ion beam device that generates an ion beam from the emitter surface by applying a high voltage between the emitter and the extraction electrode, without affecting the focusing property of the ion beam. In order to be able to perform alignment between the central axis of the ion beam and the optical axis of the beam control system consisting of condenser lens electrodes, etc., the extraction electrode that tilts integrally with the emitter and the anti-emitter of the extraction electrode Of the condenser lens electrodes provided on the side, the electrode on the most emitter side is set to the same potential.

(C. Prior art) [FIGS. 2 and 3] With high integration of ICs, LSIs, VLSIs and semiconductor devices, introduction of impurities into the surface portion of a semiconductor substrate is almost for example disclosed in JP-A-58-32346. The ion implantation method is adopted as introduced in the publication. Conventionally, an ion beam apparatus as shown in FIG. 2 has been often used for ion implantation. This ion beam apparatus is of the gas ion source type, not the liquid ion source type used in the ion implantation method described in the above publication. In the figure, a is a refrigerator, and a gas passage c through which helium He gas passes is formed at a tip portion b of the refrigerator. Reference numeral d denotes an insulating sapphire formed on the end surface of the free end portion b of the refrigerator a, and has a gas passage e communicating with the gas passage c. The gas passage e opens at the peripheral surface of the insulating sapphire d. Reference numeral f denotes a cylindrical heat radiation shield, which is provided so as to shield the periphery of the freezer tip portion e from the outside.

Reference numeral g denotes a needle-shaped emitter made of, for example, tungsten W, which is vertically provided at the center of the tip surface of the insulating sapphire d. Reference numeral h is a doughnut-shaped extraction electrode attached to the lower end of the heat radiation shield f, so that the tip of the emitter g faces the center hole thereof. The extraction electrode h is electrically grounded, and the emitter g is several KV with respect to ground.
To a positive potential of several tens of KV, the extraction electrode h is very close to the emitter g in order to generate a very high electric field on the surface of the emitter g due to the potential difference between the emitter g and the extraction electrode h. Is provided. Further, in order to increase the gas pressure of the helium He gas at the surface of the tip of the emitter g by differential evacuation while reducing the supply amount of the helium He gas, the extraction electrode h needs to be as close as possible to the emitter g.

In addition, i is an aperture that shields an ion beam deviating from a direction directly below, j is a focusing lens, k and k are alignment electrodes, l and l are grating electrodes, m is an objective lens electrode, and n and n are deflection electrodes. , O are semiconductor substrates that are irradiated with an ion beam.

Such an ion beam apparatus includes an ion gun p including members a to h for generating an ion beam, and a control system q for controlling focusing, blanking, deflection and the like on the ion beam emitted from the ion gun h. And the ion gun p and the control system q are, for example, 10
It is installed in a vacuum chamber that can create a high vacuum of ^-9 [Torr] or less. The helium He gas supplied into the heat radiation shield f through the gas passages c and e under high vacuum ionizes the atoms by the strong electric field generated by the high voltage applied between the emitter g and the extraction electrode h. , The ions are extracted downward from the surface of the emitter g through the central hole of the extraction electrode h to form the ion beam IB, and the ion beam IB deviated from the direction directly downward by the aperture i is shielded and passes through the aperture i. The formed ion beam IB is focused by the condenser lens electrode j including three electrodes.

FIG. 3 shows another conventional example. In this conventional example, the aperture i is not provided and the extraction electrode k is made to function also as the electrode j'on the most ion gun side of the condenser lens electrode j. . This is done by bringing the condenser lens electrode j closer to the emitter g so that the ions emitted from the emitter g over a wide irradiation angle are converged at a position near the emitter g and the irradiation object is irradiated with the ion beam IB. This is because the amount of beam is increased and the brightness is increased.

That is, since the ions are emitted from the emitter g over a relatively wide irradiation angle, only a small part of the ions emitted when the condenser lens electrode j is separated from the emitter g can be used as the ion beam, and the ion beam is It becomes low brightness. Therefore, in order to make the ion beam more bright, it is better to bring the condenser lens electrode j closer to the emitter g. Therefore, as shown in FIG. 3, the electrode j'on the ion gun side of the condenser lens electrode j is the extraction electrode k.
Capacitor lens electrode j
Is brought close to the emitter g, and the electrode j ′ on the ion gun side of the condenser lens electrode j is also made to function as the extraction electrode k. That is, the condenser lens electrode j
The electrode j'on the ion gun side and the extraction electrode k are used as one electrode.

(D. Problems to be Solved by the Invention) As is apparent from the above description, the ion beam apparatus shown in FIG. 2 has a high brightness because the distance between the emitter g and the condenser lens electrode j is large. It is difficult to achieve the above, and the ion beam apparatus shown in FIG. 3 is preferable in order to obtain an ion beam with higher brightness. However, in the ion beam apparatus shown in FIG. 3, when the ion gun p is tilted to align the central axis of the ion beam with the optical axis of the control system q, the focusing ability of the ion beam by the condenser lens electrode j deteriorates. Therefore, it was very difficult to mechanically align the ion gun p and the optical axis of the control system q without impairing the focusing property of the ion beam.

To explain this problem in detail, unless the central axis of the ion beam emitted from the emitter g coincides with the optical axis of the control system q, the function of the control system q cannot be effectively exhibited and a desired fine region can be obtained. Since it is not possible to perform ion implantation into the ion beam, it is necessary to tilt the ion gun p so that the center axis of the ion beam emitted from the emitter g can be aligned with the optical axis of the control system q.
However, in the ion beam device shown in FIG.
When the direction of the central axis of the ion beam with respect to the control system q is adjusted by inclining the ion gun p including the emitter g and the extraction electrode k integrally, the extraction electrode k becomes the condenser lens electrode j.
Since it also serves as the ion gun side electrode j ', the convergence state of the condenser lens electrode j is greatly reduced. This is because when the positional relationship between the ion gun side electrode j ′ of the condenser lens electrode j and the other two electrodes changes due to the alignment, the electric field strength distribution due to the condenser lens electrode j also changes, and as a result, This is because the electric field intensity distribution of the condenser lens electrode j, which has been adjusted so as to obtain a good convergence performance, is deviated.

The present invention has been made to solve such a problem, and impairs the focusing property of an ion beam while arranging the condenser lens electrode at a position relatively close to the emitter so as to obtain high brightness. It is an object of the present invention to enable alignment of the central axis of an ion beam and an optical axis without any need.

(E. Means for Solving the Problems) In order to solve the above problems, the ion beam device of the present invention has an extraction electrode tilted integrally with the emitter, and a condenser lens electrode provided on the side opposite to the extraction electrode of the extraction electrode. Among them, the electrode on the most emitter side is made to have the same potential.

(F. Action) According to the ion beam device of the present invention, the extraction electrode and the electrode on the emitter side of the condenser lens electrode are made to have the same potential while being separated from each other. Even if tilted, the electric field distribution due to the condenser lens electrode does not change, and the focusing property of the ion beam is not impaired. Therefore, the center axis of the ion beam can be aligned with the optical axis of the control system without deteriorating the focusability of the ion beam.

(G. Embodiment) [FIG. 1] Hereinafter, the ion beam device of the present invention will be described in detail with reference to the illustrated embodiment.

FIG. 1 is a block diagram showing an embodiment of the ion beam device of the present invention. In FIG. 1, 1 is an ion gun, and 2 is a beam control system for focusing, blanking, deflecting, etc. the ion beam.

Reference numeral 3 is an emitter constituting the ion gun 1, which is given a potential of +100 KV with respect to the ground. Reference numeral 4 is an extraction electrode, which is given a potential of +70 KV with respect to the ground.

Reference numeral 5 is a condenser lens electrode which constitutes the control system 2, and 3
The two doughnut-shaped electrodes 6, 7 and 8 are provided so that their central axes coincide with each other and are appropriately spaced apart from each other, and the condenser lens electrode 5 is arranged immediately below the extraction electrode 4 and very close thereto. Like the extraction electrode 4, the ion gun side electrode 6 of the condenser lens electrode 5 is given a potential of +70 KV with respect to the ground. The electrode 7 in the middle of the condenser lens electrode 5 is given a potential of +70 to 100 KV with respect to ground, and the lowermost electrode 8 of the condenser lens electrode 5 is grounded.

Reference numeral 9 is an alignment electrode, 10 is a blanking electrode, 11 is an objective condenser lens electrode, 12 is a deflection electrode, and 13 is a semiconductor wafer which is irradiated with an ion beam.

The ion beam apparatus shown in FIG. 1 can tilt the entire ion gun 1 to move the central axis of the ion beam, and the central axis can be aligned with the optical axis of the control system 2. During the alignment, the emitter 3 and the extraction electrode 4 move integrally, and the electrode 6 of the condenser lens electrode 5 moves.
Although the positional relationship of the extraction electrode 4 with respect to the electrode changes, the potential of the extraction electrode 4 is exactly the same as the potential of the electrode 6, so that the positional change of the extraction electrode 4 does not change the distribution of the electric field by the condenser lens electrode 5 at all. Therefore, there is no risk of impairing the focusing property of the ion beam during alignment, and the alignment of the central axis of the ion beam with the optical axis of the control system 2 can be performed without impairing the focusing property of the ion beam. In the ion beam device of the present invention, unlike the ion beam device shown in FIG. 2, the condenser lens electrode 5 is not separated from the extraction electrode 4, and the condenser lens electrode 5 focuses the ion beam at a position close to the emitter 3. Therefore, an ion beam with sufficient brightness can be obtained.

Although the above embodiments apply the present invention to a gas ion source type ion beam apparatus, the present invention can also be applied to a liquid ion source type ion beam apparatus.

(H. Effect of the Invention) As described above, the ion beam device of the present invention is an ion beam device that generates an ion beam from an ion source by applying a high voltage between the emitter and the extraction electrode. An electrode for focusing the beam is provided separately from the extraction electrode, and the emitter and the extraction electrode are integrally tiltable with respect to the electrode for focusing the ion beam, and the one of the electrodes for focusing the ion beam is The electrode on the side of the extraction electrode is characterized in that it has the same potential as that of the extraction electrode.

Therefore, according to the ion beam device of the present invention, since the extraction electrode and the electrode on the emitter side of the condenser lens electrode are made separate and have the same potential, the extraction electrode is tilted with respect to the condenser lens electrode integrally with the emitter. However, the electric field distribution due to the condenser lens electrode is not affected, and the focusing property of the ion beam is not impaired. Therefore, the center axis of the ion beam can be aligned with the optical axis of the control system without deteriorating the focusability of the ion beam.

[Brief description of drawings]

FIG. 1 is a block diagram showing one embodiment of the ion beam device of the present invention, FIG. 2 is a block diagram of one conventional example, and FIG. 3 is a block diagram of another conventional example. Explanation of symbols 3 ... Emitter, 4 ... Extraction electrode, 5 ... Electrode for focusing ion beam, 6 ... Extraction electrode side electrode, IB ... Ion beam.

Claims (1)

[Claims] 1. An ion beam apparatus for generating an ion beam from the surface of an emitter by applying a high voltage between the emitter and the extraction electrode, wherein an electrode for focusing the ion beam is provided separately from the extraction electrode. And the extraction electrode is integrally tiltable with respect to the electrode for focusing the ion beam, and the electrode on the extraction electrode side of the electrodes for focusing the ion beam has the same potential as the extraction electrode. Ion beam device characterized by