JPS59130057A - Sputter-ion pump for activated alloy formation-type compound cathode - Google Patents

Abstract

PURPOSE:To enable high exhaust efficiency to be obtained, by constituting cathodes which are facing each other with an anode placed therebetween, with plural kinds of metal material, and forming an alloy getter layer with very high-activity by means of sputtering on the surface of the cathodes. CONSTITUTION:Two cathodes 3, 4 facing each other with a multicell-type anode place therebetween are disposed in the pump container 1, one cathode 3 is made of aluminum, and the other cathode 4 is made of zirconium. And, a uniform magnetic field is applied to them along the axial direction of the anode 2. When a voltage is applied between the anode and cathode, cations and electrons are produced, newly produced secondary electrons further ionize other gas molecules, and cations and electrons are thus produced. These cations impinge upon the sputtering parts 3a, 4a on the surface of the cathodes 3, 4 in order to sputter aluminum atoms and zirconium atoms, and these sputtered metal atoms are cumulated on the parts 3b, 4b where each cell of the anode 2 is silhouetted. Thus, a binary alloy-getter film with high activity and made of aluminum and zirconium is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improvements in sputter ion pumps.

Sputter ion pumps use Penning discharge, magnetron discharge, or reverse magnetron discharge to ionize gas as efficiently and efficiently as possible, and the positive ions generated during the discharge are accelerated and collide with the cathode surface, which is usually made of titanium. , titanium atoms are snorted, and exhaust is performed by chemical bonding and ion trapping on the fresh titanium surface formed by snorting. Sputter ion pumps are generally based on Penning cells, and each cell consists of two cathode plates and a cylindrical anode inserted between them.
A magnetic field is applied to the axis of the anode. In addition, since the Snow ξ Tsutai ion pump is a pump that stores the gas in the vacuum system inside the pump rather than exhausting it to the outside, there is a limit to the exhaust capacity, which determines the lifespan of the pump element, and also stores the gas inside the pump. It has the tendency to release gas again, causing a phenomenon called memory effect or argon instability. In this type of orthogonal electromagnetic lift pump, the pumping speed decreases as the pressure decreases. This is because the gas that has already been evacuated is released again and becomes a gas source within the pump, reducing the effective pumping speed. It is important to keep this to a minimum. However, there are practical limits to this. Therefore, methods are known in the prior art for cooling the cathode and/or collector electrode to reduce gas re-emission. A known method for suppressing the re-release of the stored gas is to deposit a metal film on the surface and bury the stored gas.

This phenomenon is easy to induce in the case of highly efficient gases, such as those in which the cathode is the snot vine part, the fourth part is the gas trapping part, or the snot vine with a honeycomb structure. Three-electrode ion pumps and the like have been proposed in which a cathode is inserted between an anode and a collector electrode. These devices have been able to improve to some extent the drawbacks of low and unstable pumping speed for rare gases. however,
Conventional devices have not satisfactorily solved the problems of reduced pumping speed as the pumping volume approaches saturation, low pumping speed for inert gases, and re-emission of the pumped gas.

SUMMARY OF THE INVENTION An object of the present invention is to provide an active alloy-forming composite cathode sputter ion pump that has a relatively simple structure and can effectively solve the problems of pumping speed, gas re-emission, and argon instability.

Therefore, in the sputter ion pump according to the present invention, one pole placed across the anode is composed of a plurality of metal materials, and a highly active alloy getter layer is formed by sputtering the cathode surface. be done. This allows high exhaust efficiency to be obtained. Note that examples of the metal material include aluminum, zirconium, titanium, thorium, pallium, and rare earth metals.

The present invention will be further explained below with reference to the appendix.

FIG. 1 shows an embodiment of a composite cathode sputter ion pump according to the present invention, where / is a pump container, 2 is a multi-cell type anode, and two cathodes 32 or less are arranged facing each other with this anode λ in between. ing.

One cathode 3 is made of aluminum 9, and the other cathode W4'
is made of zirconium. A uniform magnetic field H is distributed along the axial direction of the anode λ. When a voltage is applied between the negative and positive electrodes by the operation of the sputter ion pump, a discharge occurs in the center of the anode cell, and the emitted electrons are attracted to the anode 2, but due to the action of the magnetic field H, the electrons perform a long spiral motion. On the way, they collide with residual gas molecules to generate positive ions and electrons, and the newly created secondary a atoms further ionize other gas molecules to generate positive ions and electrons. These positive ions form the cathode 3. The sputtered metal atoms collide with the sputtered part Ja,≠a on the coating surface of the anode, and snoset aluminum atoms and zirconium atoms, and these sputtered metal atoms mainly form the shadow part 3b of each cell of the anode λ.
, 41b to form a highly active binary alloy getter film made of aluminum and zirconium. The active gas reacts with this binary alloy book film to form a compound and is fixed, while the inert gas is buried in the deposited metal layer of the binary alloy getter film portion 3b, the layer and the anode. That will happen.

The thus formed composite getter film portion 3b, 'I
Since the getter action of b is significantly larger than that of the snow ξ ivy portion 3a, ≠a, the residual gas molecules are first captured by the composite getter film portion jb, ≠b. Therefore, the density of trapped gas molecules existing in a portion constantly exposed to ion bombardment becomes relatively small, and the amount of gas molecules re-released due to ion bombardment can be reduced.

Also, the alloy getter film is used as the cathode 3. A fresh getter surface can be easily maintained because it is constantly formed by vines on the surface of ≠, and therefore the activation process is also unpleasant.

Furthermore, cathode 3. An alloy getter film having an arbitrary component ratio can be formed by changing the type of metal material constituting the group and the area ratio of the portion facing the anode cell.

Next, the effects of the composite cathode sputter ion pump according to the present invention will be explained based on experimental examples in comparison with those of a conventional sputter ion pump.

We prototyped a composite cathode sputter ion pump using aluminum and zirconium as cathodes, and conducted performance comparison tests with a titanium cathode sputter ion pump of the same shape, and obtained the following results.

/) After evacuating hydrogen multiple times, argon was evacuated and the re-emission of hydrogen from the cathode surface was compared. As a result, the abundance ratio of hydrogen to argon in the residual gas was found to be different from that of aluminum and zirconium, as shown in Figure 2. The value in the case of the composite cathode consisting of λ was less than that in the case of the titanium cathode.

2) As shown in FIG. 3, the pumping speed for nitrogen was about λ times higher in the case of the composite cathode than in the case of the titanium cathode.

3) In the case of a composite cathode, the pumping speed for argon is more than three times higher than that of a titanium cathode, as shown in Fig.
Also, almost no argon instability was observed.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the principle of the sputter ion pump of the present invention, Fig. 2 is a graph showing the abundance ratio of hydrogen to argon in the residual gas in the pump according to the invention and a conventional pump, and Fig. 3 is a graph showing the abundance ratio of hydrogen to argon in the residual gas. Figure 1 is a graph showing a comparison example of the pumping speed for argon. In the diagram! Two anodes, 3. G: cathode, 3a, ga: snow ξ ivy portion, 3b, 'lb: alloy getter film portion. Procedural amendment (voluntary) February 15, 1980 To the Commissioner of the Japan Patent Office 1. Indication of the case 1988 Patent Application No. 5291 2. Name of the invention Active alloy producing composite cathode sputter ion pump 3. Person making the amendment Relationship to the incident Patent applicant address: 71 Chigasaki, Kanagawa Prefecture, Hagi Kai 25 (IT○ Address: Japan Vacuum Technology Co., Ltd. 4, Agent address: 105 Address: Bussan Building Annex, 1-1-15 Nishi-Shinbashi, Minato-ku, Tokyo Telephone: (591) 0261 Specification 1 Name of the invention, active alloy forming nuclear compound sputter ion pump, 24 medium g'+ 1fr=blade range [1''/defined in hollow cells It is characterized by a pair of cathodes sandwiched between a rudder body and a pair of cathodes, which are formed by forming a metal getter layer that expands and softens an alloy getter layer with very high activity due to sputtering on the cathode surface. Special JIM+ active alloy active alloy sputter ion pump with each cathode made of a different metal.
-fJ<flIi) Curvature The sputter ion pump according to item 1.1. 3 The famous cathode, which is distributed by peeling off the anode, is equipped with a plurality of different gold cup material parts, and each cathode part in a different direction is made of a different gold cup material, so that the 41.5 loss lp: 1 tolerance N1'J
Su-gutsutai ion pump described in Section 7 of Tetrasaccharide of "Ku no Kaku". , 3. DETAILED DESCRIPTION OF THE INVENTION This invention provides an improvement to the sputter nail-on pump. Sputter ion pumps use Penning discharge, magnetron discharge, or reverse magnetron discharge to ionize gas as efficiently as possible.
The positive ions spread out at a speed of 7+11 and collide with the cathode surface, which is usually made of titanium, sputtering titanium atoms, and are exhausted by chemical bonding and ion trapping on the fresh titanium surface formed by sputtering. And generally, sputter ion pumps are based on Penning cells, each cell consists of two k
Consisting of an m plate and a cylindrical anode inserted into the h
,,A magnetic field is applied to the anode wire. In addition, since the sputter ion pump stores the gas in the vacuum system inside the pump instead of ejecting it to the outside, there is a limit to the pumping capacity, and this determines the lifespan of the pump element. It also has the tendency to release the stored gas again, which is the cause of a phenomenon called argon instability, which is similar to the memory effect. This type of orthogonal electromagnetic pump - the pumping speed decreases as the pressure decreases. This is because the gas that has already been evacuated is re-emitted and becomes scarce within the pump, reducing the effective pumping speed. Therefore, in order to obtain extremely low pressure with a sputter ion pump, it is important to keep the amount of gas to be evacuated to a minimum. However, as a practical matter, there are limits to this. Therefore, methods are known in the prior art for cooling the cathode and/or the collector electrode to reduce the re-emission of gas. A known method for suppressing the re-release of stored gas is to evaporate a metal film on the surface and bury a suitable amount of gas therein. The memory effect is extracted by inert gases such as helium, neon, alkon, etc., and gases such as hydrogen, which have a weak bond with the polar surface, and this phenomenon is also likely to occur with the This is thought to be because gases with a high temperature are easily induced, and when the cathode is sputtered, the gas trapped there is also knocked out. Since hydrogen is the main component of residual gas in ultra-high vacuum systems, this effect poses a major obstacle when using sputter ion pumps for the purpose of obtaining ultra-high vacuums. Conventionally, three-electrode ion pumps have been developed in which grooves parallel to the cathode surface are provided, the convex part is used as a sputtering area, and the four parts are used as gas trapping parts, and a sputtering cathode with a honeycomb structure is inserted between the anode and the collector wire 3. I'd like some suggestions. The aim was to improve to some extent the drawbacks of these conventional methods, such as the small and unstable pumping speed t for rare gases. However, power, etc.
Conventional decorations are characterized by a decrease in pumping speed as the air volume approaches saturation and a low pumping speed for inert gases. The problem of re-emission of gas has not yet been solved to a satisfactory level. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an active alloy-forming composite cathode sputter ion pump that can effectively solve the problems of pumping speed, gas re-emission, and argon instability with a relatively simple construction. . Therefore, in the sputter ion pump according to the present invention, the anode is sandwiched between the cathodes and the cathodes, which are composed of a plurality of gold ingot materials. -Jf1 to form a layer
．． Ru. This allows high exhaust efficiency to be obtained. Examples of suitable materials include aluminum, zirconium, titanium, thorium, barium, and rare earth metals. The present invention will be further described below with reference to the accompanying drawings. Figure 1 shows an embodiment of a composite one-pole single-pole ion pump according to the present invention. ．． It is scratch resistant. - The power cathode is made of 3Vi aluminum, and the power negative is made of zirconium. And 0 of anode d! i
A uniform magnetic field H is applied along the li direction. When a voltage is applied between the negative and positive electrodes of the sputter ion pump, a discharge occurs in the center of the anode cell, and the emitted electrons are pulled from positive to negative. Due to the action of the magnetic field H, electrons move in a long spiral, collide with residual gas molecules on the way, and form positive ions and molecules.
5. The newly arrived secondary electrons ionize other gas molecules to generate positive electrons and electrons. These positive ions are the cathode 3. The sputtered portion 3a on the surface of the anode collides with aluminum atoms and sputters zirconium atoms, and these sputtered metal atoms are mainly deposited on the shadow portions 3b and 3b of each cell of the anode. However, a highly active binary alloy getter film consisting of aluminum and zirconium can be formed. The active gas reacts with this binary alloy getter film to form a compound and fix it, and the inert gas is embedded in the metal layer deposited on the binary alloy getter film portion 3b, the layer and the anode. It turns out. The composite getter # portion 3b thus formed. Since the getter action of 4tb is significantly larger than that of the sputtered parts 3a and 4'a, residual gas molecules are preferentially captured by the composite getter film parts 3b and 4b.
Ru. Therefore, the trapped gas molecules that exist in the part that is constantly exposed to ion bombardment are relatively small,
Ion bombardment can reduce the amount of gas molecules that are re-emitted. Also, the alloy ivy film is used as the cathode 3. Since the getter is constantly formed by sputtering on the surface of the getter, a fresh getter surface can be easily maintained, and therefore, the activation process is also uneven. Furthermore, cathode 3. An alloy getter film having an arbitrary component ratio can be formed by changing the area ratio of the area of the gold paper material forming the layer and the portion facing the positive image cell. Next, the effects of the composite cathode sputter ion pump according to the present invention will be explained based on Experimental Example VC in comparison with that of a conventional sputter ion pump. We prototyped a composite cathode sputter ion pump using aluminum and zirconium ELB electrodes, and conducted a performance comparison test with a titanium cathode sputter ion pump of the same shape, and the following results were obtained. l) Exhaust a large amount of hydrogen, trowel and argon,
As a result of comparing the aqueous re-release from the N-coconut surface, the abundance ratio of hydrogen to argon in the residual gas shows that the value in the case of a composite cathode made of aluminum and zirconium is the same as that of the titanium cathode, as shown in Figure 2. It was less than 2 of 1 go/7. 2) As for the I-air velocity against the nitrogen deposit, the force of the composite electrode was approximately Ω times greater than that of the titanium cathode, as shown in FIG. 3) In the case of the composite cathode, the exhaust velocity for argon was more than three times higher than that of the titanium cathode, as shown in the diagram, and almost no argon instability was observed. Brief explanation of the drawings: Figure 1 is a cross section showing the principle of the sputter ion pump of the present invention. Figure 3 is a graph showing a comparative example of the pumping speed for arsenic, and Figure 81-! is a graph showing a comparative example of the pumping speed for argon. In the figure, -2: IIM, 3.ll : Cathode, 3a, +a
Varnish batter part, 3b, dab two alloy getter film part.

Claims (1)

[Scope of Claims] Z: A metal that forms an alloy book layer with extremely high activity when a pair of cathodes placed across an anode defined in a hollow cell is caused by suction on the cathode surface. An active alloy-generating composite cathode sputter ion pump characterized by being made of a material. The ion pump according to claim 7, wherein each of the cathodes is made of a different metal material. 3. The sputter ion pump according to claim 1, wherein each of the cathodes disposed across the anode includes a plurality of different metal material parts, and each of the opposing cathode parts is made of a different metal material. .