JPS63124440A - Methode of operation analysis of semiconductor device - Google Patents

Abstract

PURPOSE:To analyze the operation of a semiconductor device accurately by a method wherein an electrode for potential waveform measurement is formed on an insulating film after a semiconductor substrate is exposed and an electron beam is applied to the electrode and secondary electrons are measured. CONSTITUTION:After resin, which is material of the sealing package of a semiconductor device, is removed and the surface of a semiconductor element is exposed, positive type resist 7 for an electron beam is applied and subjected to a baking treatment. After that, if an electron beam 8 is directly applied to the part of the resist 7 corresponding to a point of operation analysis and development treatment is carried out, an aperture 9 is formed at the part directly exposed to the beam 8. Then, after an Al layer 10 is formed, if the resist 7 is removed, the part of the Al layer 10 formed on the resist 7 is also removed and only the part of the layer 10 in the aperture 9 is left to form an electrode 11 for potential waveform measurement. As the electrode 11 has capacitive coupling with a metal wiring layer positioned below, by applying the electron beam to the electrode 11 and measuring emitted secondary electrons, the operation analysis can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for re-opening a semiconductor device that has been completed as a product, including soil molding, and analyzing its operation.

Conventional technologyIn high-density semiconductor integrated circuits represented by VLSI,
Patterns are becoming finer and wiring is becoming more multilayered. Particularly, in the semiconductor integration port 2 of the multilayer wiring structure, the wiring layer is located below the insulating film.

By the way, when analyzing the operation of a semiconductor integrated circuit with such a structure, especially when analyzing failures, it is necessary to measure the potential waveform of the wiring layer placed under the insulating film. It is difficult to measure potential waveforms depending on the metal probe.

Measuring devices that use electron beams have come to be used instead of measuring devices that use metal probes.

Measurement using this measuring device is a method in which an electron beam is irradiated to a motion analysis point on a semiconductor integrated circuit board, and the potential waveform of the wiring layer located at the motion analysis point is measured using secondary electrons generated from this portion. .

Problems to be Solved by the Invention However, if the semiconductor integrated circuit targeted for operation analysis has a multilayer wiring structure, the potential contrast may decrease due to the charging phenomenon of the insulating film covering the wiring layer. However, it was difficult to obtain highly accurate measurement results. In particular, it has already been explained that this operation analysis is performed in the J-page, such as failure analysis, but the semiconductor integrated circuit that is the target of failure analysis is usually one that has been subjected to sealing molding. Therefore, the surface of the semiconductor integrated circuit board exposed by removing the sealing envelope made of resin or the like is not covered with an insulating film.
Even if we performed a motion analysis in this state, it was not possible to obtain good measurement results.

Means for Solving the Problems The present invention has been made for the purpose of providing an operation analysis method that can eliminate such problems, and is intended to provide a method for analyzing the operation of a semiconductor device, which is an object of operation analysis. After removing the semiconductor substrate and exposing the semiconductor substrate, electrodes for measuring potential waveforms are formed on the insulating film covering the part of the semiconductor substrate that will be the point of operation analysis.
This method is characterized in that the potential waveform measurement electrode section is then irradiated with an electron beam.

Operation According to the method of the present invention, the potential change of the metal wiring layer is applied to the potential waveform measuring electrode, and the influence of the insulating film is eliminated.Examples The operation of the semiconductor device according to the present invention will be described below with reference to the drawings. The analysis method will be explained.

(Margins below) Figures 1 to 5 on page 2 show the main points of the process from the formation of potential waveform measurement electrodes on a semiconductor device to be operated to the measurement of potential waveforms. FIG.

FIG. 1 is a partially enlarged sectional view of a resin-sealed semiconductor device to be subjected to operation analysis. A metal wiring layer 4 is formed on the film 3, and a semiconductor element whose top is covered with an insulating film 5 is sealed with a resin 6.

After removing the resin that is the sealing envelope of this semiconductor device and exposing the surface of the semiconductor element, polymethyl acrylate (PMMA) was used as a positive resist for electron beams.
was applied using a spin coating method to a film thickness of 0.6 μm,
Further, a resist bake treatment is performed at a temperature of 170'C for 30 minutes.

FIG. 2 is a diagram showing the state after this processing, and as shown in the figure, the entire surface is covered with a positive resist for electron beams. After this, the semiconductor device is placed in a 6-bake electron beam exposure device, and a predetermined location, that is, a positive resist portion for the electron beam located at the motion analysis point is directly exposed with the 1 electron beam 8.
The semiconductor device is taken out from the electron beam exposure apparatus, developed with methyl isobutyl ketone (MXBK) for 60 seconds, and then post-baked at a temperature of 1120° C. for 30 minutes.

FIG. 3 is a diagram showing the state after post-baking treatment;
An opening 9 is formed in the portion directly exposed by the electron beam.

Next, as shown in FIG. 4, an aluminum layer 10 having a thickness of 0.2 μm is formed by resistance heating vapor deposition of aluminum. The aluminum layer formed in this way is
The portion formed within the opening and the portion formed on the positive resist for electron beams exhibit a separated state, or a state close to this.

When the semiconductor element subjected to the above processing is boiled with trichlorethylene and the positive resist for electron beam 77 is removed, the aluminum layer formed on it is also removed at the same time, and the aluminum layer formed in the opening is removed. Only the aluminum layer portion remains on the insulating film 5.

The potential waveform measuring electrode 11 shown in FIG. 5 is formed.

The potential waveform measurement electrode 11 formed in this way is
Since there is a capacitive coupling relationship with the metal wiring layer 4 located below, potential changes in the metal wiring layer 4 are applied to the potential waveform measuring electrode. Therefore, the operation is analyzed by irradiating this electrode with an electron beam and measuring the secondary electrons generated from this part.

In the above description, the case where one potential waveform measurement electrode is formed at one location is exemplified, but the electrodes may be formed in correspondence with the number of motion analysis points, and the number is not particularly limited.

Further, the semiconductor device to be subjected to operation analysis is not limited to semiconductor integrated circuits.

Effects of the Invention According to the present invention, since measurement is performed in a state where the potential contrast does not deteriorate, high measurement accuracy can be obtained, and the effect of enabling accurate motion analysis is achieved.

[Brief explanation of the drawing]

1 to 5 are enlarged cross-sectional views of essential parts of a semiconductor device showing the state up to the measurement of a potential waveform under the operation analysis method of the present invention. 1...Substrate support body, 2...Silicon substrate, 3...Silicon dioxide film 14...
Metal wiring layer, 6... Insulating film, 6... Resin, 7... Positive type resistor for electron beam l-, 8
, 12...Electron beam, 9...Aperture, 10
°°゛... Aluminum layer, 11... Electrode for potential waveform measurement. Name of agent Patent attorney Toshio Nakao and one other person

Claims (1)

[Claims] After removing the sealing envelope of the semiconductor device to be subjected to operation analysis and exposing the semiconductor substrate, electrodes for measuring potential waveforms are formed on the insulating film covering the part of the semiconductor substrate that will be the operation analysis point. A method for analyzing the operation of a semiconductor device, which comprises irradiating an electrode for measuring a potential waveform with an electron beam and measuring generated secondary electrons.