JPS6136376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an ion etching apparatus having an improved substrate-stage.

BACKGROUND ART In recent years, along with advances in semiconductor, integrated circuit technology, etc., rapid progress has been made in increasing the density of patterns. To meet these demands, drive processes such as plasma etching, sputter etching, and ion etching are attracting attention as they provide highly accurate patterns in place of conventional chemical etching. Among these, ion etching is particularly important (1). It can be carried out at a vacuum level of 10 ^-4 to ^{10 -5} torr, resulting in less contamination. (2)． The etching uniformity of the sample is good, and there is no edge effect. (3). Good controllability and reproducibility of etching speed. Because of these characteristics, it is attracting attention in areas such as bubble memory and ultra-high frequency devices.

The ion etching apparatus is composed of an ionization chamber, an accelerator, a neutralizing filament, a target table, etc. Usually, an inert gas such as arcon (Ar) is used as the injection gas, but oxygen (O ₂ ) or the like may also be used. Taking an ion etching device with a Kaufman type ion gun as an example, as shown in FIG. It becomes ionized. Ions accelerated by an accelerating grid 4 consisting of three grids etch a sample 6 placed on a sample stage 5. At this time, in order to prevent the sample from being charged by ions, the neutralizing filament 7 supplies thermoelectrons to the sample stage 5.

The sample stage 5 is equipped with a water cooling mechanism 8 to reduce heat generation due to ion bombardment. Further, in order to increase the uniformity of etching, a rotation mechanism can be added to the sample stage 5.

In these etching apparatuses, when forming a fine pattern, a mask pattern is usually formed using photoresist, and using this as a mask, ion etching is performed using a shower-shaped ion beam. At this time, an essential condition for forming a good pattern is to suppress the temperature rise due to ion bombardment of the sample. As a result of actually measuring the temperature rise of a sample due to ion bombardment, the temperature rise is (1). Proportional to the incident ion power (product of incident ion energy and ion current density), (2). (3) It largely depends on the degree of thermal contact between the sample and the sample stage. As long as a good contact condition is obtained, the effect is almost the same regardless of the type of heat sink agent.

For example, when the ion energy is 500 eV and the ion current density is 0.50 mA/ ^cm2 , the temperature is 130°C on a 0.15 mm thick glass substrate that is in mechanical contact with the sample stage, metal gallium is used as a heat sink material between the sample stage and the glass substrate, and vacuum is applied. When using grease, diffusion pump oil, silver paste, etc., the temperature rises by 13℃. As described above, in ion etching, the quality of thermal contact between the sample and the sample stage is an important factor.

However, when actually using these heat sink agents, ease of use is important. For example, if the viscosity is low, such as diffusion pump oil, when a vacuum is applied, air bubbles may scatter and contaminate the sample surface, and if the viscosity is high, it may be difficult to apply it uniformly.
Furthermore, if these are irradiated with an ion beam, harmful gases may be released, which may adversely affect pattern formation. It is also important that these heat sink agents can be easily peeled off.

On the other hand, even if these heat sink agents are used, if ion etching is performed repeatedly for a long time, the surface of the sample table on which the sample is not placed will be etched by ions, resulting in a step on the sample table. The difference in level causes poor thermal contact with the sample, making it difficult to obtain a good pattern. In addition, the atoms of the sputtered sample stage material have a residual distribution (Possen; a sputtering method for coating the inner wall of a through hole on a substrate;
technique for coating inside walls of
through-holes in substrates.J.Vac.Sci.
Technol.) Vol. 11-5, 1974, p. 875), the etching particles scatter in all directions and adhere to the side wall 10 of the sample substrate in proportion to the etching time, as shown in FIG. The adhesion of this adhesive layer is not very good, so it may peel off during the next process, such as resist removal or ultrasonic treatment for cleaning.
It adheres to the sample surface and causes defects.

The present invention improves thermal contact between the sample and the sample stand by applying simple processing to the sample stand, prevents deformation of the sample stand, and prevents the sample stand material from adhering to the side wall of the sample substrate. The purpose of the present invention is to provide an etching device.

In the apparatus according to the present invention, the sample stage includes a removable auxiliary sample stage made of a material with a large thermal conductivity coefficient and processed with protrusions or recesses for positioning, and a sample stage cover that is hollowed out to match the protrusions or recesses. Consists of. Suitable cover materials include ion etching, slow-etching titanium (Ti), molybdenum (Mo) plates, etc., and the cutout needs to be slightly smaller than the outer diameter of the sample to be etched.

Next, the present invention will be explained in detail using the drawings.

An embodiment of the sample stage in the ion etching apparatus of the present invention is shown in FIG. A removable auxiliary sample stand 12 is installed on the sample stand 5 via a suitable heat sink agent 11. The position of the auxiliary sample stage 12 is slightly convex in accordance with the shape of the sample 6. This convex portion is made only for the number of etching samples and is used to always mount them at the same position. The sample 6 is placed on an auxiliary sample stage 12 via a suitable heat sink material 9. A copper (Cu) plate or the like having good thermal conductivity is suitable for this auxiliary sample stage 12. Furthermore, the sample stage cover 1 is hollowed out to be slightly smaller than the outer diameter of the sample 6.
3 over the auxiliary sample stage 12. This sample stage cover 13 is provided to prevent damage to the auxiliary sample stage 12 due to ion etching and to prevent sputtered atoms from adhering to the side wall of the sample 6. The auxiliary sample stage 12 is not necessarily necessary, but the sample stage 5
A similar effect can be expected even if the material is processed directly on the main body.

When the viscosity of the heat sink agent 9 is low, the fourth
Better effects can be expected by using the auxiliary sample stage 12 having the structure shown in Figures a and b. FIG. 4 is a diagram showing another embodiment, in which a is a sectional view and b is a top view. The portion of the sample 6 is recessed by the sum of the thickness of the sample 6 and the thickness of the heat sink agent 9, and a heat sink agent retaining groove 14 is dug around it. This groove 14 serves as a reservoir for excess heat sink agent 9. Numerals 15 and 16 are grooves for mounting and removing the sample, making it easy to hold the sample with tweezers or the like. By digging such a groove, it is possible to prevent the heat sink agent from getting around to the sample surface. Reference numeral 13 designates a sample stage cover similar to that shown in FIG. 3, and is made of a material with a slow ion etching rate.

As a specific example of the sample stage shown in FIG. 4, an auxiliary sample stage 12 made of a copper (Cu) plate with a thickness of 2.5 mm is connected to a GGG substrate for bubbles (cadrinium gallium garnet) made of a 2-inch wafer with a thickness of 0.4 mm. ), drill a hole 0.5 mm deep and 50 mm in diameter, and then make a groove 14 around it with a depth of 20 mm, inner diameter of 50 mm, and outer diameter of 56 mm.
Open the hole and dig 120 grooves 15 in each direction in 3 directions with a depth of 20 mm and a width of 3 mm. Vacuum grease is applied to the recessed part of the auxiliary sample stand 12 where the sample is to be placed and heated to 100° C. with a hot plate, and the sample 6 is mounted in a state where the viscosity becomes low. At this time, excess vacuum grease is collected in the groove 14. Next, the auxiliary sample stage 12 is placed on the sample stage 5 with vacuum grease interposed therebetween. The auxiliary sample stage 12 is electrically connected to the sample stage 5 to prevent charging. Furthermore, a 2 mm thick titanium plate (Ti) with a 48 mmφ hole drilled thereon is placed on the auxiliary sample stand 12 as a sample stand cover 13. The position of the sample stage cover 13 is determined by a convex edge 17 provided around the auxiliary sample stage 12. After the ion etching is completed, the auxiliary sample stage 12 is separated from the sample stage 5 and heated to 100°C using a hot plate.
Insert tweezers through the groove 15 and remove the sample 6. The sample thus obtained was able to provide a good pattern with few defects because no adhesion layer was formed on the side wall of the substrate.

Incidentally, an apparatus having such a sample stage is not limited to an ion etching apparatus, but can also be effectively used as a reverse sputtering apparatus, for example.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the ion etching apparatus, and Fig. 2 is a diagram showing a normal sample stage and a method for mounting the sample, and shows how atoms emitted from the sample stage adhere to the side wall of the sample substrate. There is. FIG. 3 is a sectional view showing one embodiment of the sample stage in the apparatus according to the present invention, and FIG. 4 is a diagram showing another embodiment of the sample stage in the apparatus according to the present invention, in which a is a sectional view;
b is a top view. 1... Gas injection port, 2... Ionization chamber, 3...
Magnet, 4... Acceleration grid, 5... Sample stand, 6... Sample, 7... Middle loading filament, 8
...Water cooling mechanism, 9...Heat sink agent, 10...
Sample substrate side wall, 11... Heat sink agent, 12...
...Auxiliary sample stand, 13...Sample stand cover, 14...
Heat sink agent reservoir groove, 15, 16... Groove for sample handling, 17... Convex edge.

Claims (1)

[Scope of Claims] 1. In an ion etching apparatus, a sample stage for holding a sample to be etched is fixed to a main body of the apparatus and is water-cooled; An auxiliary plate part whose surface has been processed in advance according to the shape; a cover made of a material with a slow ion etching rate and arranged to cover the auxiliary plate part and the side surface of the sample to be etched placed on the auxiliary plate; An ion etching device comprising: 2. The ion etching apparatus according to claim 1, wherein the material having a slow ion etching rate is titanium or molybdenum.