JPH01235244A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable conditions of a fine aperture formed in an insulating film to be inspected non-destructively, by forming a second aperture simultaneously with formation of a first aperture such that the second aperture has substantially the same configurations as those of the first one and reaches a semiconductor substrate or a second conducting layer electrically connected with the semiconductor substrate, and scanning the surface of the second aperture with an electron beam for observing a current image of the sample. CONSTITUTION:When an N-channel MOS transistor is to be inspected, a dummy MOS transistor having the same configurations as those of said N-channel MOS transistor under test is provided on an N-type semiconductor substrate 1 beside said transistor to be tested, through the same processes as those of said transistor to be tested. A proper contact hole 12 and a monitoring contact hole 13 are formed simultaneously so as to have the same configurations. When a current image of the sample is observed by means of a conventional SEM, a desirable current image of the sample can be obtained in the monitoring contact hole 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a semiconductor device that enables inspection of the formation state of fine windows formed in an insulating film in the manufacturing process of a semiconductor device. Regarding.

In recent years, the scale of semiconductor devices, especially semiconductor integrated circuits, has been rapidly increasing, and higher integration is strongly desired.

For this reason, microfabrication techniques, mainly photolithography, are being developed. Semiconductor devices whose smallest part has a dimension of 1 μm or less have also come into practical use.

Along with this, the inspection of processing conditions during the manufacturing process has been replaced by a higher resolution SEM (SEM), replacing the conventional optical microscope.
canning Electron Microsco
[Conventional technology] Conventionally, the method of inspecting the processing state in the manufacturing process of semiconductor devices has been widely used by SEM (secondary electron observation). It is used. However, when trying to observe the shape of an opening such as a contact hole formed in an insulating film using a SEM, the
& The film is negatively charged by electrons, resulting in so-called charge-up, which prevents the emission of secondary electrons from inside openings such as contact holes, and as a result, good secondary electron images cannot be obtained. There is a problem that the shape is difficult to inspect. Therefore, conventional methods have been used to reduce this charge-up, such as tilting the semiconductor wafer to be observed with the SEM with respect to the incident electron beam, or lowering the acceleration energy of the electron beam. .

In the method of tilting a semiconductor wafer, as contact holes become finer and the ratio of the depth to the width of the opening, that is, the aspect ratio, increases, tilting the semiconductor wafer causes the bottom of the contact hole to become smaller. There is a problem that it becomes impossible to observe, and in addition, in the method of lowering the energy of -kudenshi, when this energy is lowered,
There was a natural limit because the absolute number of secondary electrons emitted from semiconductor wafers decreased, making observation gradually more difficult, and the resolution decreased.

A method of inspecting the shape of a contact hole with a large aspect ratio is to destroy a semiconductor wafer by cutting it, etc., and observe the cross section of the wafer with an SEM. However, this method requires processes such as cleavage, which takes time, and since it is a destructive test, it causes loss of semiconductor wafer, so it cannot be used in reality on mass production lines. .

Therefore, in a mass production line, as a method of inspecting the formation state of contact holes, etc., the semiconductor wafer 1 to be inspected is scanned and irradiated with an electron beam of low acceleration energy using an SEM, and nine parts are irradiated with the electron beam. A method has been proposed in which the current flowing through the semiconductor U/S is detected, the sample electric current is obtained, and the flow of this sample is observed.

[Problems that the invention attempts to resolve]

By observing the sample current image using the SEM described above,
9 Inspection of the shape of openings such as contact holes that reach the surfaces of n-type or p-type semiconductor substrates, n-type semiconductor regions formed on p-type semiconductor substrates, or electrodes that are electrically connected to these. However, the opening to be inspected is n! If it is formed on the surface of a p-type semiconductor region surrounded by a tl semiconductor region or on a conductive layer electrically connected to this p-type semiconductor region, there is a problem that it cannot be inspected.

FIG. 2 is a diagram illustrating the problem of observing this sample current image. This diagram shows the n+
Contact hole 34 reaching diffusion layer 25. n-substrate 21
A contact hole 32° reaching the p+ diffusion layer 23 formed in the upper p-wafer 22 and a gate electrode 31 of an n-channel MO8 type transistor formed in the p-well 22 are opened. Contact hole 3 reaching the power n+diffusion l-24 which becomes the region
3 is a diagram schematically showing a process of observing a current image of the sample using an SEM and inspecting the formation state of the contact hole after opening each of the contact holes.

Among the cholera contact holes, regarding the contact hole 34 that is delayed to the n+ diffusion layer 25, here is the electron beam 26
When irradiated, the injected electrons 27 can diffuse within the n-type substrate 21 and flow out to the outside. The current flowing out from this n-type substrate 21 is amplified by an amplifier 28, and SE
By imaging in the image section 29 of M, a sample current image of the contact hole 34 can be obtained, and its formation state can be inspected.

However, in the case of the contact holes 32 and 33 formed on the p-well 22, although the electrons 27 injected by the electron beam 26 diffuse into the p-well 22,
The current cannot flow from the p-well 22 toward the substrate 21 across the p-n junction at the interface between the p-well 22 and the n-type semiconductor substrate 21, which is in a reverse bias state, and as a result, no current flows to the outside. For this reason, the contact hole 32
It is not possible to observe the sample current image at .degree. 33, and the contact holes 32 and 33 cannot be inspected by this method. Also, since the contact hole 34 and the contact holes 33 and 32 are usually different in shape and size, the sample current image of the contact hole 34 is simply the color contact hole 33,
It was also difficult to examine the state of formation of 32.

The present invention was created in order to overcome the shortcomings of conventional methods, and is a method for manufacturing a semiconductor device that makes it possible to non-destructively inspect the formation of nine minute openings in an insulating film. Its purpose is to provide money.

[Interval IIt-Means for solving]

The purpose of this is to cover the surface of a p-type semiconductor region formed on a semiconductor and surrounded by an n-type semiconductor region, or the surface of a conductive layer in series 1 that is electrically connected to the p-type semiconductor region. A method for manufacturing a semiconductor device comprising the steps of forming an insulating film and forming a first opening in the insulating film that reaches the p-type semiconductor region or the first conductive layer, wherein the first opening At the same time as forming the part, its shape changes to the first part.
This is achieved by scanning and irradiating the surface of the opening of the front handle 2 with an electron beam and observing the sample current image of the second opening. .

[For production]

In the method for manufacturing a semiconductor device of the present invention, inspection can be performed using a sample current image, and the shape of the opening to be inspected and the opening for monitoring the formation state whose shape is between the two are as described above. Since it is formed at the same time as the opening to be inspected, the formation state of the opening to be inspected can be determined by observing the sample current through this formation state monitoring opening.

〔Example〕

FIG. 1 is a diagram illustrating one embodiment of the present invention, in which an n-channel MO8m formed in a p-well 2 on an n-type semiconductor substrate 1 is shown.
This figure shows a case where the formation state of a contact hole 12 reaching an n+ diffusion layer 3 which is to become a source/drain region of a transistor is inspected.

The difference from the conventional method described above is that a dummy MO8 transistor structure of the same shape for inspection is placed on the nW semiconductor substrate 21 immediately next to the n-channel MO8 transistor to be inspected. This is because it was formed through the exact same process as that used to create the transistor (apnel MO8ffi). The original contact hole 12 and the monitor contact hole 13Fi have the same shape and are formed at the same time. After this, the sample current image was observed using a SEM in the same way as before, and a good sample current image was obtained in the monitor contact hole 13, which indicated that the monitor contact hole 13 was formed at the same time. It was possible to know the formation state of contact hole 12, which should become a component of an actual semiconductor device. In this embodiment, when forming the monitoring contact hole 13, a dummy electrode 14 that is not directly used is also formed, but this may depend on the shape of the insulating film 10 and the contact hole etched into the insulating film. Since the shape of 12 depends on the surface shape of the underlying portion, this purpose is to reduce the influence of differences in the surface shape of the underlying portion.

Incidentally, such monitoring contact holes 13 may be appropriately placed on the semiconductor wafer for each number of openings to be inspected, and by installing them, the utilization efficiency of the semiconductor wafer can be improved. The drop is practically not a problem.

Furthermore, even if fi4p and p-)n were used in this example, the effects of the present invention remained the same.

In this embodiment, a contact hole is shown, but a so-called peer hole between wiring layers can be similarly configured as a monitoring peer hole. In other words, if you want to know the formation state of a peer hole formed on a wiring layer that is connected to a semiconductor substrate only through a bond, check the formation status of a peer hole that is connected to an N-type diffusion layer and has almost the same shape including the periphery. It is sufficient to prepare a layer, open a window in almost the same shape on the layer, and observe the current image of the sample through this window.

Moreover, the application of the present invention is not limited to these examples,
It is clear that the present invention is applicable regardless of the type S of the device to be manufactured or the conductivity type of the semiconductor used.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to non-destructively inspect the formation state of minute openings with a large aspect ratio formed in an insulating film, regardless of the shape of the openings, and the manufacturing process can be completed in a short time. Since feedback can be provided to the process, there is an effect that the throughput and manufacturing yield of semiconductor device manufacturing are improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating problems in conventional sample current image observation, and FIG. 2 is a diagram illustrating an embodiment of the present invention. In the figure, 1.21 is an n-type semiconductor substrate, 2.22 is a p-well, 3.24.25 is an n-diffusion layer, 4 is an element isolation region, 10.30 is an insulating film, 11.31 is a gate electrode, 12, 32, 33, and 34 are contact holes, 13 is a contact hole for monitoring, 14 is a dummy electrode, 26 is an electron beam, 27 is an electron, 28 is an amplifier, and 29 is a SEM unit.茅l Drawing procedure amendment (method) 63.6.07 Showa year, month, day, 1986 Patent Application No. 061478 2 Title of invention Method for manufacturing semiconductor devices 3 Relationship with the case of the person making the amendment Patent applicant address Kanagawa Prefecture 1015 Kamiodanaka, Nakahara-ku, Yozaki-shi Name (522) Fujitsu Limited Representative Takuma Yamamoto 4 Agent Postal code 211 5 Number of inventions increased by amendment None 1) In line 20 of page 1 of the specification of the present application , "3. Detailed description of the invention" is added.

Claims (1)

[Claims] P formed on a semiconductor and surrounded by an n-type semiconductor region
forming an insulating film so as to cover the surface of the p-type semiconductor region or the surface of the first conductive layer electrically connected to the p-type semiconductor region; forming a first opening that reaches a first conductive layer;
forming a second opening that is substantially the same as the opening and that reaches the semiconductor substrate or a second conductive layer electrically connected to the semiconductor substrate; and a surface of the second opening. A method for manufacturing a semiconductor device, comprising the step of inspecting the formation state of the opening by scanning and irradiating the sample with an electron beam and observing a sample current image of the second opening.