JPS60143643A - Energy analytical device - Google Patents

Abstract

PURPOSE:To realize an energy analytical device, by which secondary electrons emitted from a sample can be efficiently detected and the voltage of an internal wiring having been provided in the IC of the sample can be accurately measured, by a method wherein a voltage made to conform to a field-effect distribution is impressed on magnetic substance sleeves provided on the periphery of the electron beam path. CONSTITUTION:When an electron beam 6 is irradiated on the position of an internal wiring, which has been provided in the IC of a sample 5 and a measurement of the voltage of which is needed, secondary electrons 10 are emitted from the wiring position. At this time, the energy of the secondary electrons 10, which are emitted, has become a magnitude according to the value of voltage having been impressed on the internal wiring irradiated, and by detecting the secondary electron 10, which passed through a lead-out grid 7, a buffer grid 8 and an analytical grid 9, by a scintillator 11, the magnitude of voltage of the internal wiring in the IC of the sample 5 is found out. Here, a voltage is conformed to a field-effect distribution to change by a voltage, which is impressed on the scintillator 11, and when the optimum voltage is impressed on magnetic substance sleeves 1 by a movable voltage power source 4, the secondary electrons 10, which are emitted from the analytical grid 9, can be all detected by the scintillator 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an energy analyzer for measuring wiring voltage of an integrated circuit, and more particularly to an energy analyzer having a magnetic shielding member around an electron beam path.

(2) Background of the Invention In recent years, the circuit density of integrated circuits and mounted printed boards has improved, and the wiring within integrated circuits and mounted printed boards has become as narrow as several microns. If a defect occurs in an integrated circuit or the like having such thin wiring and it is desired to measure the wiring voltage, it is difficult to directly apply a metal probe to the wiring. Therefore, instead of using a metal probe, we irradiated it with an electron beam.

An energy analyzer that measures the wiring voltage of a sample by detecting secondary electrons emitted at that time is attracting attention.

(3) Prior art and problems In voltage measurement using a conventional energy analyzer, an electron beam is irradiated from an electron gun onto a position on a sample where the wiring voltage is to be measured. Secondary electrons with energy determined by the magnitude of the wiring voltage are emitted from the wiring position of the sample irradiated with the electron beam, and these secondary electrons are accelerated by a grid etc.
Detected by secondary electron detector. The magnitude of the energy of the detected secondary electrons changes by an amount corresponding to the magnitude of the wiring voltage to be measured. Therefore, the wiring voltage of the sample can be determined from the amount of change in the energy of the secondary electrons detected by the secondary electron detector.

However, in the case of this device, a shield cylinder is provided around the electron beam path to prevent the electron beam irradiated onto the sample from being influenced by external stray magnetic fields.

However, since no voltage is applied to this shield cylinder, the electric field distribution within the energy analyzer becomes OV near the shield cylinder. For this reason, among the secondary electrons heading toward the secondary electron detector to which a high voltage is applied, those with a shield cylinder located on their path cannot reach the secondary electron detector. Therefore, the secondary electron detector cannot detect all the secondary electrons emitted from the sample, reducing the secondary electron detection efficiency. For this reason, it is impossible to accurately measure the wiring voltage of the sample, which has the drawback of lowering energy analysis performance.

(4) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional art, the present invention provides that by applying to the shield cylinder the same potential as the electric field in which the shield cylinder is located on the electric field distribution, the secondary electron detector can emit radiation from the sample. An object of the present invention is to provide an energy analyzer that can efficiently detect secondary electrons and accurately measure the wiring voltage of a sample.

(5) Structure of the Invention According to the present invention, the above object is to provide a magnetic shielding member around an electron beam path, detect secondary electrons emitted by irradiating a sample with an electron beam, This is achieved by providing an energy analysis device that measures voltage, characterized in that a voltage is applied to the magnetic shielding member.

(6) Examples of the invention Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an energy analyzer according to the present invention.

In the figure, a cylindrical magnetic sleeve 1 is placed below an objective lens 2 via a spacer 3, and is given a constant DC voltage by a voltage applied from a variable voltage power source 4. The magnetic sleeve 1 is used to prevent external stray magnetic fields from affecting the direction of the electron beam 6 that exposes the sample 5, and the objective lens 2 focuses the electron beam 6 onto the target circuit of the sample 5. It is used for irradiation.

Three grids are provided concentrically at a constant distance from the sample 5. The inner grid is drawer grid 7
and the middle grid is buffer grid 8,
The outer grid is analysis grid 7 grid 9. The extraction grid 7 has a small energy of secondary electrons 10 emitted when the sample 5 is irradiated with the electron beam 6 (several eV to several tens of eV).
V) For.

This is a grid for extracting the secondary electrons 10 to the outside of the extraction grid 7, and a voltage of about 1 kV is applied thereto. Since a high voltage is applied to the buffer grid 8 and the extraction grid 7, this high voltage may affect other devices in the electron beam device.
A voltage of about 0V is applied. Analysis grid 9 is 2
A grid that controls secondary electrons emitted to the outside of the analysis grid 9 depending on the energy of the secondary electrons 10.
Usually a voltage of OV to 5cm is applied.

A scintillator 5- detecting the emitted secondary electrons 10 A light vibrator 12 is provided at one end of the motor 11.

Scintillator 11. A cover 13 is provided over the light pipe. scintillator 11
When detecting secondary electrons 10, it emits light to the light pipe 12 side depending on the size of the detected secondary electrons 10, and since the energy of the secondary electrons 10 is small, the power source 14
A high voltage of 10 KV is applied to create an electric field distribution within the energy analyzer to attract secondary electrons 10. In addition, the light incident on the light pipe 12 is transmitted through a photomultiplier tube (
(not shown) into an electrical signal. In the energy analyzer configured as above, an example will be described below in which the sample 5 is an integrated circuit (hereinafter referred to as IC) and the internal wiring voltage of the IC is measured.

When an electron beam 6 is irradiated onto an internal wiring position within an IC that requires voltage measurement, secondary electrons 10 are emitted from the wiring position. The energy of the secondary electrons emitted at this time depends on the voltage value applied to the irradiated internal wiring, and the higher the applied voltage, the lower the energy of the secondary electrons 10 becomes. . The emitted secondary electrons pass through the extraction glyph 1, 7, buffer grid 8, and are sent to the analysis grid 9. Whether or not the emitted secondary electrons are emitted to the outside is determined by the amount of energy.

FIG. 2 is a diagram showing the relationship between the amount of secondary electrons emitted to the outside from the analysis grid 9 and the analysis grid voltage applied to the analysis grid 9.

Curve 1 shows when the wiring voltage of sample 5 is 5■, and curve 1 shows when the wiring voltage of sample 5 is OV. As shown in the figure, even if the same analysis grid voltage is applied, the amount of secondary electrons emitted to the outside of the analysis grid 9 differs depending on the wiring voltage. Therefore, the secondary electrons 10 that passed through this analysis grid 9
The IC of sample 5 is detected by the scintillator 11.
The magnitude of the internal wiring voltage can be seen.

Here, the electric field distribution outside the analysis grid 9 is shown by equipotential lines in FIGS. 3 and 4.

FIG. 3 shows a conventional electric field distribution diagram when IOK'V is applied to the scintillator 11 and no voltage is applied to the magnetic sleeve 1.

FIG. 4 is an electric field distribution diagram when 10 KV is applied to the scintillator 11 and 5 KV is applied to the magnetic sleeve 1. 15 is the electron beam irradiation position of sample 5, and A
Section, B section, and 0 section each indicate a portion where the secondary electrons 10 are emitted to the outside of the analysis grid 9.

Since electrons have the property of being incident at right angles to the electric field, the secondary electrons 10 emitted from each of sections A to C of the analysis grid 9 are as shown in FIG. 3 when no voltage is applied to the magnetic sleeve 1. Proceed in the direction shown.

Therefore, the secondary electrons 1o emitted from the B section and the 0 section cannot be accurately detected by the scintillator 11.

However, when a voltage of 5V is applied to the magnetic sleeve 1 as in the present invention, most of the secondary electrons 1o emitted from each of sections A to C of the analysis grid 9 are directed toward the scintillator 11 as shown in FIG. Proceed to.

Of course, the secondary electrons 10 emitted from portions other than portions A to C of the analysis grid 9 also reliably enter the scintillator 11.

Therefore, all the secondary electrons 10 emitted from the analysis grid 9
The scintillator 11 can detect. The secondary electron signal accurately detected by the scintillator 11 is sent to the light pipe 12. The internal wiring voltage of the IC, which is the sample 5, can be accurately indicated through the photoelectron amplification tube.

As described above, the present invention has not been practiced before. By applying a voltage to the magnetic sleeve 1, secondary electrons 1
By changing the electric field distribution between the analysis grid 9 and the scintillator 11 through which 0 passes, all of the secondary electrons 10 that have passed through the analysis grid 9 are transferred to the scintillator 11.
1. This makes it possible to obtain an accurate voltage value for the sample 5.

The present invention is not limited to the above embodiments, and the voltage applied to the magnetic sleeve 1 is not limited to 5V, but the voltage applied to the scintillator 11 is
The optimum voltage is applied to the magnetic sleeve 1 by the variable voltage power supply 4 in accordance with the electric field distribution that changes depending on the voltage applied to the magnetic sleeve 1.

(7) Effects of the Invention As explained in detail above, according to the present invention, by applying a voltage matching the electric field distribution to the magnetic sleeve, all secondary electrons emitted from the sample can be The secondary electron detector can detect efficiently and accurately measure the wiring voltage of the sample.

Furthermore, since secondary electrons can be detected efficiently, secondary electrons can be detected even when the voltage applied to the scintillator for creating an electric field distribution is lower than that of conventional devices.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an energy analyzer according to the present invention. FIG. 2 is a characteristic diagram of the analysis grid, FIG. 3 is an electric field distribution diagram when the magnetic sleeve has zero potential, and FIG. 4 is an electric field distribution diagram when 5V is applied to the magnetic sleeve. 1... Magnetic sleeve 2... Objective lens 3... Spacer 4... Variable voltage power supply 5... Sample 6... Electron beam 7... Extraction grid 8... Buffer grid 9. ...Analysis goo 10- Lid 1o...Secondary electron 11...Scintillator 12...Light pipe 13...Cover 14...Power source 15...Electron beam irradiation position 11-Ii-Station arrogance number Difference 2

Claims (1)

[Claims] A magnetic shielding member is provided around the electron beam path. An energy analysis device for detecting secondary electrons emitted by irradiating a sample with an electron beam and measuring a wiring voltage on the sample, characterized in that a voltage is applied to the magnetic shielding member.