JPS58106733A - Ion gun - Google Patents

Abstract

PURPOSE:To increase the dielectric strength between a pin-like chip and an opposed electrode, and make an ion gun compact by providing an insulator block, which supports the electrode and electrically insulates the electrodes from the outside of the ion gun, with grooves of specified dimensions so that the electrodes are surrounded by the grooves. CONSTITUTION:An electrode 3 is provided with a pin-like chip 1 used for ion generation. Grooves 8 are provided on, for example, the upper and the lower surfaces of an insulator block 4 which supports the electrode 3 and electrically insulates the electrode 3 from the outside of an ion gun. When the outer diameter and the thickness of the insulator block 4 are supporsed to be D and T respectively, the width (W) and the depth (l) of the grooves 8 are restricted within the range D/50<=W<=D/3 and T/50<=l<=T/2. By thus providing at least one groove 8, which has dimensions within the above ranges, around the electrodes 3, the voltage resistance of the ion gun can be widely increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion gun useful for ion beam application equipment such as ion microanalyzers.

As an ion gun that emits a narrow, high-intensity ion beam,
Ion guns that ionize gas or liquid metal in a high electric field are known. As shown in Figure 1, gas or liquid metal is supplied to a needle tip 1 to which a high positive voltage is applied to a counter electrode 2, and the gas or liquid metal is ionized by the action of a high electric field near the surface of the needle tip. It is something to do. Since a high voltage of several kV or more is applied between the needle tip 1 and the counter electrode 20, the holding electrode 3 of the needle tip is fixed to an insulator block 4 having electrical insulation properties. This insulator block is made of materials with good electrical insulation properties, such as quartz, alumina, stairdite, and glass. In recent years, in order to improve the performance of this type of ion gun, the voltage applied between the needle tip 1 and the counter electrode 20 has tended to increase. Furthermore, when gas is ionized, it is necessary to effectively supply the gas to the vicinity of the needle tip, and a simple gas supply method is desired.

The present invention has been made in view of these points, and it is an object of the present invention to provide an ion gun that has a large dielectric strength between a needle tip and a counter electrode, and has a compact shape. Furthermore, an ion gun that ionizes gas is designed to simplify gas supply.

The present invention will be explained in detail below.

The voltage resistance between the needle tip and the counter electrode, or between the needle tip and surrounding parts, is determined by the spatial distance between the needle tip and the counter electrode or surrounding parts, and the insulation from the electrode with the needle tip to the surrounding parts. Determined by the lower of the edge distances on the body block.

According to the experiments of Misfire #14 et al., it was found that in a normal ion gun, the withstand voltage is determined mostly by the latter. The main cause of this is that metal evaporated from the needle tip during the operation of the ion gun or impurities generated by ion bombardment adhere to the surface of the insulator block, reducing the dielectric strength voltage in the direction of the edge. . In order to prevent this, it is possible to sufficiently increase the outer diameter of the insulator block, but in this case a problem arises in that the dimensions of the ion gun become too large. Practically speaking, it is desirable that the ion gun be as small as possible.

The ion gun of the present invention is characterized in that the insulator block is provided with at least one groove surrounding the electrode. As will be clear from the explanation given later with reference to the drawings, when two electrodes are surrounded by one groove at the same time, it is sufficient to have at least one groove. However, when surrounding each of the two electrodes with one groove, a total of two grooves are required.

The width W and depth t of the groove are the outer diameter t-D of the insulator block,
When the thickness is T, it is preferably in the range of D150 x W x D/3 T150 x T/2, especially when T/20<, t
More preferably, the range is T/2.

FIG. 2 is a sectional view t5 of an embodiment of the ion gun of the present invention, and FIG. Although Fig. 2 shows an example in which grooves 8 are provided on both the upper and lower surfaces of the insulating block, it is not necessary to provide the grooves on the upper part.
Although it is sufficient to have a groove surrounding the lower electrode 3, it is more effective to provide it also in the upper part. When providing a groove on the upper part as above, the depth of both the lower groove and the upper groove is T.
/2, the insulation block will be cut.

Therefore, approximately 1/1o of the thickness T of the insulating block needs to be left. That is, if the depth of the lower groove is t and the depth of the upper groove is t/, it is necessary that /, +t' + 9/IOT.

If the lengths of W and t are W)D/4 or t>T/2, the groove becomes too large and the strength of the insulator block decreases, causing cracks to occur at the corners where stress is concentrated. W<
D150 generally presents machining difficulties. z＜'r
/2o, the withstand voltage cannot be effectively improved. By providing one or more grooves 8 in the above range so as to surround the electrode 3', the withstand voltage can be improved by a large degree. The improvement in withstand voltage due to the provision of the groove increased in proportion to the distance from the edge surface of the insulator block passing through the groove from the electrode 3 to the opposing electrode.

Therefore, by appropriately selecting the depth of the grooves and the number of grooves depending on the magnitude of the applied voltage, it is possible to maintain the desired withstand voltage.

FIG. 3 shows another embodiment of the insulator block provided with grooves, which can be arbitrarily selected depending on the purpose of the side piece of the ion gun, processing cost, etc. Figure 3 (A), (Q and [
F] is the cross-sectional view, and ■, 0 and [F]
2 shows the A-A cross-sectional views of 0, 0, and 2, respectively.

In Fig. 3 (■), the groove is provided perpendicularly to the pole axis of the laminate. In this case as well, the groove depth t is as effective as C1 in improving the withstand voltage. , it is necessary to keep the width within a range where the electrodes are not exposed69, and the width of the groove W is the same range as above with the outside diameter and thickness T of the insulator block changed, that is, the range of T150 x W x T/3. It is necessary to define

However, since the groove is dug perpendicularly to the electrode axis, the outer diameter of the insulator block becomes larger than that shown in FIG. 3 (2). From the point of view of manufacturing a compact ion gun with a small outer diameter, it is preferable to dig #I substantially parallel to the electrode axis as shown in FIG. 3 (5), 0.

Figure 4 shows the main parts of an ion gun that ionizes gas, and here, in addition to grooves 8 to improve withstand voltage, holes 9 for gas supply are provided in the insulator block. . In order to increase the ionization efficiency in an ion gun that ionizes gas, it is necessary to cool the needle tip 1 and the supply gas to approximately the same temperature. 'The ion gun shown in FIG. 4 is of a preferred configuration for rounding for this purpose, and the gas reaches approximately the same temperature as the insulator block in the process of passing through the hole 9t provided in the insulator block.

Since the needle tip is fixed to an insulator block, the tip is at the same temperature as the cylinder, and in the case of the ion gun shown in FIG. 4, gas is efficiently ionized.

Furthermore, by adopting a method of supplying gas through an insulator block, the shape of the ion gun can be simplified, so that the cost of manufacturing the ion gun can be reduced. In the figure, 11 is the head of the cooler.

It should be noted that the present invention is not limited to the shape shown in FIG. 4, and the conventional method shown in FIG. 1 may be used for gas supply.

Examples will be described below.

Example 1 An ion gun having the structure shown in FIG. 2 was manufactured using sintered AlZ as the insulator block material. A needle tip made of W was wetted with liquid Ga and used as a Ga ion gun.

Outer diameter D1 of insulator block, thickness T1, d w of groove, depth of groove 11, D==12aa.

T=20 fights, W=2m%, t=S-.

When the withstand voltage between the needle tip and the counter electrode was measured in a 10-"Toll vacuum, it was found to be over 15 kV.Furthermore, even when the ion gun was operated for more than 100 hours, the withstand voltage was over 15 kV. was maintained.In contrast,
With an ion gun that does not have grooves or an insulator block of the same size, the withstand voltage characteristics deteriorate in 50 to 90 hours;
Leakage current started flowing at 15kV. #It was found that the withstand voltage characteristics were improved by using an insulator block with a top layer.

Example 2 An insulator block having the structure shown in FIG. 3(A) VC was produced using a steer die, and an ion gun was produced using this. Insulator block outer diameter D5 thickness T1 groove width W% ml
depth 11, D=20wn, T=30txx.

W=1.5101t L=10wn. In this case as well, substantially the same effects as in Example 1 were observed.

Example 3 An insulator block having the structure shown in FIG. 3 (Q) was prepared using glass. An ion gun was manufactured using this. The outer diameter and thickness T of the insulator block were set to D=10 mm, T =20sg
It was set as I. The dimensions of the groove are width W = 11g.

The depth was 1 = 5 mm on the electrode side of the needle tip, and t = 13 wm on the opposite side. Even after operating the ion sink for over 100 hours, it was able to maintain a withstand voltage of over 10 kV.

Example 4 An ion gun having the structure shown in FIG. 4 was manufactured using sapphire as the insulator block material. Outer diameter D of insulator block 4: 30111% Thickness T = 40 m.

- Dimensions of the groove provided on the side where the needle-like tip is attached are as follows: Inner groove width w = 2■, depth t = 10wms, outer groove width W
= 4sag, depth t = 18Ell, width W of the groove provided on the opposite side to these = 2rxx, and depth 19m.

Furthermore, a hole 9 with a diameter of 1 inch for gas supply was provided through the insulator block. Using a needle tip 1 with <111> orientation, H* is passed through the gas supply pipe 10.
* He @ N e @ A r + X e I
A gas such as K r gN was introduced into the tip of the needle tip to generate ions of the gas. In order to increase the ionization efficiency, the entire ion gun is mounted on the head 11 of the cooler.
It is configured so that the optimum temperature can be set in the range of 4 to 200 degrees Celsius. The withstand voltage between the needle tip 1 and the counter electrode 26 was 30 kV or more. 30kV for over 100 hours using any of the above gases
We were able to obtain the above-mentioned withstand voltage characteristics and operate stably as an ion gun.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an ion gun that ionizes gas in a high electric field, FIG. (Q, ([), [F] and [F] are cross-sectional views showing other embodiments of the shape of the insulator block of the ion gun according to the present invention,
FIG. 4 is a diagram showing the configuration of an ion gun for gas ion generation according to the present invention. ■...Acicular tip, 2...Counter electrode, 3...Holding electrode of needle-like tip, 4...Insulator block, 5...
Leak pulp, 6... Gas cylinder, 7 River ion beam lens, 8... Groove, 9... Gas supply hole, 10
...Gas combined weight 1 Figure

Claims (1)

[Claims] 1. An ion gun comprising an electrode with a needle-like tip for ion generation, and an insulator block that holds the electrode and has electrical insulation from the outside, wherein the insulator is An ion gun characterized in that the block is provided with at least one groove surrounding the electrode. 2 The groove is connected to the electrode shaft in the insulator block! 1l
The outer diameter t of the insulator block is
-D, thickness 'kT, width W and depth t of the above groove
The ion gun according to claim 1, wherein D150, W, D/3, T150<, t<, T/2, respectively. λ The ion gun according to claim 2, wherein the depth t of the groove is in the range of T/20<t<T/2. 4. The ion gun according to claim 1, wherein the groove is provided perpendicularly to the electrode axis in the insulator block. 5. The depth of the groove is such that the electrode axis is not exposed, and the width W of the groove is T150, W<T, where the thickness of the insulator block is 't-T. /3 range lol! The ion gun according to item 1, the range of IFn requirements. 6. The ion gun according to claim 1, wherein at least one groove is provided in each of the upper and lower parts of the insulator block. 7. The groove is provided substantially parallel to the electrode axis in the insulator block, and when the outer diameter tD and the thickness tT of the insulator block, the width W' and depth of the upper groove are Sat
' and the width W and depth t of the lower groove are in the range of D150<W'<D/3 T150<,t'<T/2 D150×D/3 T150×/,×T/2, respectively. and the value of t+t' is L+1'9
7. The ion gun according to claim 6, wherein the ion gun has a value in the range of /10T. 8. The ion gun according to claim 7, wherein the depths t' and t of the grooves are in the range of T/20t'<, T/2 T/20t<, T/2. . 9. The ion gun according to claim 1, wherein at least 41 or more ion guns are provided in the groove, perpendicular to the electrode axis in the insulator block, and at the top and bottom of the insulator block, respectively. 10. The ion gun according to item 1, wherein at least one groove is provided for each of the electrodes.