JPS5885533A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To permit in-line inspection process after dry etching by a method wherein an electron beam is irradiated on the processed surface and both resultant secondary electron beam image and characteristic X-ray image are used to inspect a pattern. CONSTITUTION:An Si substrate is placed in a connector 4 held under vacuum similar to an etching chamber 1, and the surface including a pattern is scanned by a minute spot-like electron beam emitted from an inspection unit 5. Upon irradiation of the electron beam, secondary electrons and X-rays are generated from the surface of the Si substrate in accordance with the state thereof. A secondary electron beam image and an X-ray image are produced on monitor screens of both SEM and EPMA constituting the inspection unit 6 in a corresponding fashion. By comparing the secondary electron beam image with the reference pattern or photoresist film, it is possible to check whether an plane image of the pattern formed on the Si substrate surface is acceptable or not. Meanwhile, it is also possible from the X-ray image to detect the presence or absence of residuals of etching and over-etching by comparing with the secondary electron beam image.

Description

DETAILED DESCRIPTION OF THE INVENTION (11) Technical Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to an in-line inspection method for a lie notching process.

(2) Background of the technology As semiconductor devices become increasingly dense and highly integrated, such as LSI and VLSI, reactive sputter etching methods, etc., which are suitable for in-line manufacturing processes, are becoming more and more popular. Dreyer.

With the introduction of etching (dry etching) methods, in-line manufacturing processes for semiconductor devices are progressing.

(3) Conventional technology and problems In the inspection process of a processed sample after dry etching, the surface of the processed sample is carefully observed by an operator or with a microscope to check for engraving residues and over-etching. Visual inspection by highly skilled workers was the only option available. Therefore, as mentioned above, even though the dry etching process itself can be done in-line, the inspection process cannot be done in-line, and this has hindered complete in-line manufacturing of semiconductor devices.

(4) Object of the Invention An object of the present invention is to provide a method for manufacturing a semiconductor device which solves the problems mentioned in 2 above and enables in-line inspection of a sample to be processed after dry etching.

(5) Structure of the Invention A feature of the present invention is that after performing a dry etching process on a sample to be processed, and before taking out the sample to be processed into the atmosphere, the surface to be processed of the sample to be processed is irradiated with an electron beam. detecting secondary electrons and characteristic X-rays generated by the process, and inspecting a pattern formed on the surface of the sample to be processed using the obtained secondary electron beam image and characteristic X-ray image. There is a particular thing.

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 are views showing the above embodiment, FIG. 1 is a front view of main parts of the dry etching apparatus used in the above embodiment, and FIGS. 2 to 5 are diagrams showing the main part of the dry etching apparatus used in the above embodiment. FIG. 4 is a cross-sectional view and a curve diagram of main parts for explaining the effect.

In FIG. 1 above, ■ is the etching chamber, which is the main body of the dry etching apparatus, 2 is a loader for loading the sample to be processed, 3 is a connector that connects the loader 2 and the etching chamber 1, and 4 is the etching chamber. A connector 1 connects the device to the next stage or the outside; 5 is an inspection device for dry-etched samples; and 6 is a second etching chamber. The medium inspection device 6 is composed of a scanning electron microscope (SEM 3) and an electron beam microanalyzer (EPMA).

Next, the method of dry etching of this embodiment using the dry etching apparatus mentioned above and the method of inspecting the sample to be processed will be explained.

First, a sample to be processed such as a silicon (Si) substrate (not shown)
A special container called a cassette containing the 3i substrate is attached to the loader 2, and the 3i substrate to be processed is introduced into the etching chamber 1 via the connector 3.

This 3i substrate is then subjected to a desired dry etching process such as reactive sputter etching. The Si substrate on which the predetermined pattern has been formed is then connected to the coupler 4.
sent to. In the dry etching apparatus of this embodiment, the coupler 4 is constructed to also serve as an inspection chamber, in which the pattern formed on the surface of the Si, L plate is inspected.

The inside of the coupler 4 is kept in a vacuum like the etching chamber 1 so as not to expose the Si substrate to heat. The Si substrate is placed at a predetermined position in the coupler 4, and the coupler 4
The patterned surface of the Si substrate is scanned by an electron beam in the form of a minute spot from an inspection device 5 provided at the top. When irradiated with an electron beam in this manner, the surface of the Si substrate generates secondary electrons and X-rays corresponding to the surface condition. These are detected by the SEM and EPMA constituting the inspection device 6, respectively, and a secondary electron beam image and an X-ray image are drawn in correspondence with each other on the monitor screens of the SEM and EPMA.

By comparing the secondary electron beam image drawn on the monitor screen of the SEM with a standard pattern or a photoresist film used as a dry etching mask, it is possible to determine whether the planar image of the pattern formed on the surface of the Si substrate is good or not. It is possible to inspect the line width, linearity, etc. of a pattern. On the other hand, by correlating the X-ray image drawn on the EPMA monitor screen with the secondary electron beam image, it is possible to detect the presence or absence of etching residues and over-etching in various parts of the pattern.

This inspection method will be explained using FIGS. 2 to 5. Second
Figure +al ~ (C1 and Figure 4 +a+, (bl
51 is a cross-sectional view of the main parts showing an example of forming wiring made of aluminum (AI) on a 51 substrate lI in the order in which dry etching progresses, and FIGS. 3 and 5 are drawn corresponding to each of the above states. 3 is a curve diagram showing an X-ray spectrum of a pattern edge portion (position indicated by an arrow in the figure) of a photoresist film 14. FIG. Figure 2 [al is the state before the start of etching, 1.1
is a Si substrate, and 12 is silicon dioxide (Sin, ) I! which covers the surface of the S1 substrate 11. , 13 is aluminum (AI
) III and I4 are photoresist films formed according to a predetermined pattern. In the X-ray spectrum in this state, a spectrum indicating <AI appears strongly, as shown by curve 21 (solid line) in the figure. Next, as the etching progresses and the thickness of the AI layer 13 decreases as shown in the same figure (bl), the X-ray spectrum becomes weaker as shown by curve 22 (dashed line), and the spectrum of A1 becomes weaker, and the spectrum of 3i becomes weaker. As the etching progresses further and the surface of the Si substrate becomes exposed, the spectrum of A1 becomes even weaker as shown by curve 23 (dotted chain line), and the spectrum of Sj becomes very strong.

FIGS. 4 ta) and 4 (b) are cross-sectional views of main parts emphasizing the details of FIG. 2 tc), and FIG. , the same figure (b) shows the state where Al113 is over-etched. Curve 24 (dotted chain line) 2 in Figure 5
Curve 25 (double-dashed line) is shown in FIG. 4 above (al,
Corresponds to (b). In FIG. 4(a), since A1 exists in the pattern edge part, the spectrum of curve 24 is 81.
is strong<Si is weak. On the other hand, as shown in FIG. 4(b), excessive etching occurs. Then, in the X-ray spectrum, as shown by curve 25, 8l becomes weaker and Si becomes stronger.

By irradiating an electron beam in this manner and detecting the generated characteristic X-rays corresponding to the position, it is possible to know the material of the surface at that location and its film thickness. Note that 3i0. It has been explained that when Rg is irradiated with an electron beam, Si is detected, but this is because the above detection method clearly detects 3i of the two constituent elements of Sin, whereas 0. This is because it is almost impossible to detect.

In this embodiment, by utilizing this, as described above, the 3i substrate of the sample to be processed is irradiated with an electron beam in the coupler 4, and the generated secondary electrons and characteristic X-rays are detected, thereby exposing the surface of the sample to be processed. It detects the dimensions of the formed pattern and the excess or deficiency of etching. This result is immediately feedbanked and
Dry etching is appropriately controlled by in-line processing, such as performing additional etching on the sample in the second etching chamber 6 and determining the etching amount, and adjusting the etching amount of the sample to be processed subsequent to the sample. It becomes possible. Moreover, even for materials such as AI, whose surface condition changes once exposed to air and makes it difficult to perform etching, the inspection method of this example involves performing dry etching and then testing the sample to be processed. Since it can be carried out in a vacuum without being taken out into the atmosphere, it is easy to add an etching process.

The present invention is not limited to the above-mentioned embodiment, but can be implemented with various modifications.

For example, in the above embodiment, SEM and EPM are used as inspection devices.
Although A was used, it goes without saying that a dedicated inspection device consisting of an electron gun, an electron beam detector, and an X-ray detector may be manufactured and used instead.

Furthermore, the present invention can be applied not only to the etching of AI, but also to the inspection of dry etching of any other commonly practiced materials.

As described above, according to the present invention, it is possible to carry out the inspection process after dry etching in-line, and it becomes easy to carry out in-line manufacturing processes for semiconductor devices. Further, in the present invention, since a series of steps are consistently performed in a vacuum, the sample to be processed can be kept clean at all times, and the manufacturing process is stabilized. Furthermore, if the etching results are undesirable, it is possible to immediately correct, change, or add etching conditions from the inspection device in response to the failure mode.

/

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the method for manufacturing a semiconductor device of the present invention.
A front view for explaining the manufacturing equipment used, and FIGS. 2 to 5 are diagrams for explaining the inspection method of this example.
Figures 2 and 4 are cross-sectional views of the main parts showing the state of the inspection target position of the sample to be processed, and Figures 3 and 4 are the detected XIt
Qsubek1ram is drawn corresponding to the state of the above-mentioned inspection target position. In the figure, 1 is an etching chamber, 5 is an inspection device, 11 is a semiconductor substrate, 12 is a Sin film, and I3 is A1 of a film to be processed.
layer, 14 is a photoresist film, 21 to 25 are X-rays /θ

Claims (1)

[Claims] When forming a predetermined pattern on the surface of a sample to be processed by the dry etching method, after performing the dry etching process on the sample to be processed, and before taking out the sample to be processed, the surface of the sample to be processed is removed. Secondary electrons and characteristic X-rays generated by irradiating the surface to be treated with an electron beam are detected, and the obtained secondary electron beam image and characteristic 1. A method of manufacturing a semiconductor device, comprising a step of inspecting a pattern.