DD139670A3 - DEVICE FOR PREPARING THE SUBSTANCE SAMPLES FOR INVESTIGATION - Google Patents

Abstract

The invention relates to a device for preparing material samples for examination in scanning electron microscopes or other devices for microstructure analysis. The aim of the invention is to improve the quality of sample preparation. The invention solves the problem of exposing the near-surface layers of the sample at a selected location by making a cut along a defined path, whereby the cut surface is representative of the material structure. According to the invention, this problem is solved in that a parallel ion beam for ablating sample material is directed towards the edge of a diaphragm located directly above or directly on the sample and forms an angle of less than 90° with the sample surface. With this device, any solid body, even non-solid ones such as fibers or powders, can be prepared for the analysis of the microstructure in near-surface regions, including the large group of samples that suffer excessive structural disturbances during mechanical preparation. After prior drying, organic substances, especially biological ones, can also be prepared for examination.

Description

Apparatus for preparing the swatches for the study

Field of application of the invention

The invention relates to a device for preparing the substance samples for examination in scanning electron microscopes or other devices for analyzing the microstructure. With the device, the near-surface layers are cut and exposed for examination. The device can be used, for example, for inspecting microelectronic components.

Characteristic of the known technical solutions Mechanical grinding methods are known which serve to make oblique sections of layers near the surface of plague body samples visible. For example, a spherical cap is machined out of the surface in the ball-and-socket process. At their planks, a beveled surface is created by the surface, whose angle of inclination depends on the depth of the polished section.

The known grinding methods have the drawback that the position of the ground point on the surface can not be determined with microscopic accuracy. They are therefore only applicable if the layer structure is the same in larger surface areas. Furthermore, mechanical grinding methods can only be applied to those materials that are brittle ger.ug to resist complete destruction (smearing) in the Schiiffzone. In any case, however, will

The structure in the ground zone significantly affected, for example, by destruction of the crystal lattice and the generation of dislocations into areas that are several tenths of a millimeter from the closing surface. The layer disturbed by the mechanical attack falsifies the examination results, above all, if, in addition to the light microscopic examination, other surface-physical examination methods are also to be used. For example, the orientation contrast is lost for the observation with the Easter electron microscope.

In mechanical methods of surface erosion, ion beam methods are known which serve the purpose of creating defined surface structures. In these methods, the surface is sputtered vertically with an ion beam in a vacuum. Within a given area, evenly thick layers are removed. Various components of the sample are selectively degraded by the directly incident ions. There is no representative of the material structure sectional area.

Object of the invention

The aim of the invention is to improve the quality of the sample preparation au.

Explanation of the essence of the invention

The invention solves the problem of exposing the near-surface layers of the sample at a selected location through a cut in a defined path, wherein the cut surface is representative of the material structure.

According erfindungsgeinäß the object is achieved in that a parallel ion beam for removing sample material is directed to the edge of a diaphragm, which is located just above or directly on the sample, and forms with the sample surface iron angle less than 90 °. Preferably, the elements are housed in deia scanning electron microscope and adjustable by means known per se for moving ^ barriers and turning in their position with respect to the direction and the point of impact of the electron beam on the Pr top surface from the outside.

2 4 JAN 19 7 d * fi -S ¹ J ii 2

The panel is attached to or over the sample and aligned. At an oblique angle, the sample surface and the aperture are then bombarded with parallel ions. At the sharp shadow border creates an embankment area. The created excavation surface represents a section through the sample and has the following properties: Its position and shape in the material is determined by the type and arrangement of the diaphragm and the direction of incidence of the ion beam. The embankment surface is not affected by directly incident ions and therefore is not selectively degraded when the sample is composed of different components. It is not mechanically stressed, but only struck by scattered ions. It is therefore representative of the structure of matter and can now be examined by both electron microscopic means and other materials analysis methods (e.g., microanalysis) and provides information about the structure of the sample. It is particularly advantageous if the elements are housed in the scanning electron microscope (SEM) and can be adjusted from the outside. The desired object site can be selected under the microscope and the cut surface made at this point without having to remove the sample again. The section can be made under observation and interrupted for analysis. The correct position of the cut can be controlled and corrected.

It is also possible to firmly apply the shielding screen as an anti-spattering material to a part of the sample surface, e.g. evaporate.

Sample preparation is also applicable to non-compact material, i. cuts can also be made through porous material, fibers or microparticles. It is applicable to all substances which are resistant to vacuum, ie also to biological samples, when they are dried in a known manner as before each electron microscopic image.

The invention will be illustrated below on an exemplary Beiepiel.

The drawing shows the erfindungsgeinäße solution in a scanning electron microscope.

  - 4 -

In the object space of the scanning electron microscope (SEM), an ion emitter 1 is mounted so that a parallel ion beam strikes the sample surface in the region 8 which is also struck by the electron beam 4 of the SEM. The sample 9 is located on a cross table 10, which can be moved in a known manner from the outside by two adjusting drives in two mutually perpendicular directions 11, 12 of the sample surface. On this cross table, the diaphragm 14 is arranged so that it can be moved by an adjusting ebenfalle from the outside in the direction 13 above the sample surface and so the position of the desired section «surface 6 can be set. Furthermore, means are provided to rotate the sample in the cross table about an axis perpendicular to the sample surface 5 and to tilt the cross table so that this axis in any direction between the direction to the ion beam 1, fier direction to the electron beam 3 and the direction to the electron detector that can not be in a plane, can be adjusted ..

The ion radiator 1 supplies a parallel bundle of noble gas ions whose energy can be selected between 5 and 12 keV. The

Ion density at the object is up to 20 μA / mm. The ion beam direction is close to the detector direction. Between the ion emitter and the sample, a swing-out Faraday cup is mounted, with which the ion beam can be measured, optimized, faded in and out. The aperture is coarsely pre-adjusted on the sample surface and is finely adjusted with a helical drive that can be operated from outside via a flexible shaft. _E The diaphragm edge, which defines the cutting line on the sample surface, is approximately parallel to the tilt axis of the object plane.

The sample is imaged in the SEM to determine the location of the desired cut line. Subsequently, the sample table is removed from the microscope, the panel is placed close to the surface of the sample and coarsely adjusted using a magnifying glass. Thereafter, the sample is again imaged in the SEM, whereby the aperture can already be adjusted more precisely. A quick turn on the ion beam (by swinging the Faraday cup in and out) marks the cut line and allows the

iQ J

final personalization. The desired inclination of the cut surface in the sample is set with the tilt angle of the sample plane to the ion beam. The ion beam is now switched on until reaching the desired removal depth. The control over this can be carried out either directly during the bombardment by imaging the sample with backscattered electrons or during switching on pounding with secondary electrons.

Claims (2)

Erfindvmgsanspruch 1, apparatus for the preparation of the substance samples for examination in a scanning electron microscope or other devices for analyzing the microstructure, characterized in that a parallel ion beam for removing sample material on the hand of a diaphragm (14), which closely over or directly euf the sample is located, and with the sample surface forms an angle less than 90 ^ö . 2, device according to item 1, characterized in that its elements are housed in the scanning electron microscope and adjustable by means known per se for moving, pivoting and rotating in their position relative to the direction and the point of impact of the electron beam (4) on the sample surface from the outside , HiefB ~ i _ ". $ Eüei drawings