JP3185774B2 - Standard sample for contact hole inspection, its manufacturing method and contact hole inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a standard sample for evaluating the thickness of a residual film remaining on the bottom surface of a contact hole when inspecting a contact hole formed in a semiconductor device, a method for manufacturing the same, and a method for manufacturing the same. The present invention relates to an inspection method using a standard sample.

[0002]

2. Description of the Related Art A contact hole has a structure in which a hole is opened in an insulating film or the like having a thickness of several thousand mm formed on a supporting substrate or the like of a semiconductor device. The contact holes are usually formed by etching such as RIE (reactive ion etching). Contact holes formed by etching are often not complete openings. As a result, the insulating film or the like may remain on the bottom surface of the contact hole that should originally penetrate from the surface of the insulating film or the like to the surface of the support substrate.

For this reason, a non-destructive contact hole opening inspection apparatus has been developed which non-destructively inspects the state of an opening of a formed contact hole. In the inspection of a contact hole by this apparatus, a contact hole of a semiconductor device to be inspected placed in a vacuum chamber of the apparatus is
As shown in FIG. 17, the electron beam EB is irradiated. The part irradiated with the electron beam EB emits secondary electrons.
Then, the secondary electrons are detected by a secondary electron detector, and a secondary electron image is observed.

When the acceleration voltage of the electron beam is about 1 kV, the energy of the secondary electrons is at most several eV (electron volts). The magnitude of this energy is determined by the work function of the material of the portion irradiated with the electron beam.

Further, the emission efficiency of the secondary electrons, that is, whether or not the secondary electrons reach the secondary electron detector and are detected is mainly determined by the surface potential of the irradiated portion of the electron beam. For example, as shown in FIG.
2 penetrates through the insulating film and the supporting substrate 10 is exposed at the bottom surface, and when the remaining film 44 remains at the bottom surface of the contact hole 42 due to insufficient etching. Are different. as a result,
The contrast of the secondary electron image differs between the contact hole 42 having a sufficient opening and the defective contact hole having an insufficient opening because the emission efficiency of the secondary electrons emitted from the bottom surface is different.

For example, when the back surface of the semiconductor device to be inspected is grounded, the bottom surface of the contact hole where the underlying support substrate is exposed looks black in the secondary electron image.
In contrast, the bottom surface of the contact hole in which the remaining film remains on the bottom surface looks white in the secondary electron image. Therefore, the contrast of the image differs depending on the presence or absence of the remaining film, and thus the presence or absence of the remaining film can be detected. That is, it is possible to make a qualitative judgment on the presence or absence of the remaining film.

[0007]

In opening a contact hole by etching, it is desirable to stop the etching immediately after the underlying supporting substrate is exposed at the bottom of the contact hole. This is because, if the etching is continued after penetrating the contact hole, the damage to the underlying substrate increases. Therefore, in order to determine the optimum etching conditions (such as etching time) for forming a contact hole while accurately penetrating the layer to be etched and minimizing damage to the underlying substrate, a residual film remains on the bottom surface of the contact hole. In such a case, it is necessary to measure the thickness of the remaining film.

[0008] However, conventionally, in the secondary electron image, the thickness of the remaining film cannot be measured, although the presence or absence of the remaining film can be detected. For this reason, conventionally, after detecting a defective contact hole by observing a secondary electron image, a cross-sectional TEM (transmission electron microscope) image of the contact hole is further observed to measure the remaining film thickness of the defective contact hole. I needed to. As a result, conventionally, it took a long time to measure the remaining film thickness.

In addition, in order to prepare a sample for observing a cross-sectional TEM image, an advanced technique such as the use of a FIB (Focused Ion Beam) is required. Further, the observation range of the TEM is extremely narrow as compared with the observation range of the secondary electron image. For this reason, it was extremely difficult to measure the remaining film thickness of all the defective contact holes found in the secondary electron image.

The present invention has been made to solve the above-mentioned problem, and has as its object to provide a technique for easily obtaining the remaining film thickness at the bottom surface of a contact hole.

[0011]

In order to achieve this object, the inventor of the present application has conducted various experiments and studies, and as a result, the contrast of the bottom surface of the contact hole in the secondary electron image has been reduced. We paid attention to the fact that it depends on the thickness. Then, by comparing the contrast of the bottom surface of the contact hole in the secondary electron image with the contrast of a standard sample having a known remaining film thickness, it was conceived that not only the presence or absence of the remaining film but also the remaining film thickness could be easily measured.

However, the thickness of the remaining film is usually several Å to
Very thin, several hundred square meters. For this reason, it is extremely difficult to intentionally control the remaining film thickness accurately to the thickness of several to several tens of millimeters and perform etching. For this reason, it was practically impossible to form a standard sample whose remaining film thickness was controlled by etching. Therefore, the inventor has conceived of using a flat plate having a pseudo residual film having a known film thickness formed on the surface of a supporting substrate as a standard sample capable of controlling the film thickness.

However, the current value of the secondary electrons is affected not only by the remaining film thickness but also by the surface shape of the semiconductor device in which the contact hole is formed. For example, secondary electrons emitted from the bottom surface are absorbed by the side wall of the contact hole or affected by a complicated electric field inside the contact hole. Therefore, even if the thickness of the standard sample of the flat plate is the same as that of the actual remaining film of the contact hole,
The contrast of the secondary electron image will be different. Therefore,
Even if a flat plate is used as a standard sample, it is difficult to accurately measure the remaining film thickness.

For this reason, as a result of further studies and experiments, the inventor of the present invention has found that a resin layer having an opening corresponding to a contact hole is laminated in a pseudo residual film shape using a photosensitive resin. For example, the inventor has conceived that a contrast of a secondary electron image similar to that of an actual contact hole can be obtained.

According to the standard sample for contact hole inspection according to the first aspect of the present invention, a pseudo residual film having a known film thickness and a resin obtained by curing a photosensitive resin are provided on a support substrate. Layers are sequentially laminated, and an opening is provided in the resin layer to penetrate the resin layer.

As described above, according to the standard sample for contact hole inspection according to the first aspect of the present invention, instead of forming a pseudo residual film by etching, a pseudo residual film having a known film thickness is formed on a supporting substrate. Further, a resin layer having an opening corresponding to a contact hole is formed thereon by curing a photosensitive resin.

As a result, the same structure as that in which a residual film having a known thickness remains on the bottom surface of the contact hole by etching can be obtained. As a result, in the secondary electron image, the remaining film thickness can be easily obtained by comparing the contrast of the opening of the standard sample with the contrast of the contact hole to be inspected. Further, the residual film thickness can be easily obtained by comparing the through current value of the standard sample with the through current of the inspection object.

If a photosensitive resin is used, the opening can be patterned without damaging the pseudo residual film. For this reason, a resin layer having an opening having an arbitrary aspect ratio can be formed thereon without practically damaging a very thin pseudo residual film having a thickness of, for example, several Å.

The limit of the fine processing of the opening size is simply determined by the limit of lithography. On the other hand, the fine processing limit of the contact hole size to be inspected is also determined by the fine processing limit of lithography. Therefore, even if the size of the contact hole is very small, the size of the opening of the standard sample can be made basically the same as the size of the contact hole to be inspected.

Further, the material of the pseudo remaining film is the same as the material of the remaining film remaining on the bottom surface of the contact hole to be inspected. As described above, according to the second aspect of the present invention, since the pseudo residual film having a known thickness is formed of the same material as the residual film actually formed on the bottom surface of the contact hole to be inspected, the secondary electron image is formed. Can be made closer to the actual contrast and the through current value of the bottom surface of the contact hole. As a result, the thickness of the remaining film can be more accurately evaluated.

According to a third aspect of the present invention, the plane size and the aspect ratio of the opening of the remaining film are the same as the plane size and the aspect ratio of the contact hole to be inspected. Thus, according to the third aspect of the invention,
Since the standard sample is formed in the same shape as the shape of the contact hole to be inspected, the contrast and the through current value in the secondary electron image can be made closer to the actual contrast and the through current value of the bottom surface of the contact hole. As a result, the thickness of the remaining film can be more accurately evaluated regardless of the surface shape of the semiconductor device.

According to a fourth aspect of the present invention, the pseudo residual film is provided only on a part of the support substrate, and the photosensitive resin is provided with openings in the formation region and the non-formation region of the pseudo residual film. . Thus, according to the invention of claim 4, one standard sample is provided with an opening having a pseudo residual film and an opening having no pseudo residual film. For this reason, it is possible to obtain a contrast between a case where the aperture is complete and a case where the aperture is incomplete with one standard sample.

Further, the electrical characteristics of the contact hole formation layer (the same material as the remaining film) of the actual semiconductor device,
The electrical characteristics of the resin layer are usually different. In particular, among the electrical characteristics, the dielectric constant is generally such that the value of the resin layer is larger than the value of the contact hole formation layer. The contrast and the through current value of the secondary electron image may be different due to the difference in the electrical characteristics of the resin layer.

Therefore, the invention according to claim 5 is configured such that the dielectric constant of the resin layer is equal to the dielectric constant of the contact hole formation layer to be inspected. As described above, according to the fifth aspect of the present invention, since the dielectric constant of the resin layer is made equal to the actual dielectric constant of the contact hole formation layer, the contrast and the through current value in the secondary electron image of the standard sample are reduced. The contrast and the through current value of an actual contact hole having a remaining film of the same thickness can be made closer. As a result, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device, an impurity diffusion layer is often formed as a base to be exposed at the bottom of the contact hole. The contrast and the through current value of the secondary electron image may differ depending on the presence or absence of the impurity diffusion layer.

According to a sixth aspect of the present invention, there is provided a structure in which an impurity diffusion layer having the same impurity type and impurity concentration as the impurity diffusion layer formed on the support substrate to be exposed at the bottom of the contact hole to be inspected is provided on the support substrate. There is. With this configuration, according to the present invention, even if the impurity diffusion layer is provided on the support substrate of the semiconductor device to be inspected, the contrast and the through current value in the secondary electron image of the standard sample are provided. Can be made closer to the contrast and the through current value of an actual contact hole having a remaining film of the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device, a well to be exposed at the bottom of the contact hole is often partially formed with a well. The contrast of the secondary electron image and the through current value may differ depending on the presence or absence of the well at the contact hole formation position.

In view of this, a seventh aspect of the present invention has a structure in which a part of the support substrate is provided with a well having the same impurity type and impurity concentration as the well formed on the support substrate to be exposed on the bottom surface of the contact hole to be inspected. . With such a configuration, according to the invention of claim 7, even when the well is provided immediately below the contact hole of the support substrate of the semiconductor device to be inspected, the contrast in the secondary electron image of the standard sample is improved. In addition, the through current value can be made closer to the contrast and the through current value of the actual contact hole having the remaining film having the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device, the underlying substrate to be exposed at the bottom of the contact hole is S
OI substrates are increasingly used. Then, depending on whether the support substrate is an SOI substrate or not,
The contrast and the through current value of the secondary electron image may be different.

Therefore, in claim 8, the supporting substrate is made of SO
It is characterized by using an I (silicon on insulator) substrate. With such a configuration, according to the invention of claim 8, even when the support substrate of the semiconductor device to be inspected is an SOI substrate, the contrast and the through current value in the secondary electron image of the standard sample are the same. It can be made closer to the contrast and through current value of an actual contact hole having a residual film having a thickness. As a result, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device,
In some cases, an insulating film is provided on the back side of the substrate. When such a semiconductor device is irradiated with an electron beam,
Depending on the presence or absence of the insulating film on the back side, the contrast and the through current value in the secondary electron image may be different.

Therefore, in the ninth aspect, an insulating film is provided on the back surface of the support substrate. As described above, according to the ninth aspect of the present invention, since the insulating film is provided on the back surface of the support substrate, even when the back surface insulating film is provided on the semiconductor device to be inspected, the secondary electron image of the standard sample is provided. Can be made closer to the contrast and the through current value of an actual contact hole having a remaining film of the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device,
Contact holes are provided at various intervals. For this reason, the planar distribution density of the contact holes varies. The contrast and the through current value of the contact hole in the secondary electron image may differ depending on the planar distribution density of the contact hole.

Therefore, in the tenth aspect, the plurality of openings are unevenly arranged in the resin layer so that the planar distribution densities of the openings are different from each other. As described above, according to the tenth aspect of the present invention, since the openings are provided at various plane distribution densities, the openings having the same distribution density as the plane distribution density of the contact holes to be inspected are selected to obtain the standard sample. Of contrast. As a result, the contrast and the through current value in the secondary electron image of the standard sample can be made closer to the contrast of the actual contact hole having the remaining film of the same thickness.
Therefore, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device,
Contact holes having various aspect ratios are provided. The contrast and the through current value of the contact hole in the secondary electron image may be different depending on the aspect ratio of the contact hole.

In view of this, the present invention is configured such that a plurality of openings having different aspect ratios are provided in the resin layer. As described above, according to the eleventh aspect, the openings having various aspect ratios are provided.
An opening having the same aspect ratio as the aspect ratio of the contact hole to be inspected can be selected to obtain the contrast of the standard sample. As a result, the contrast and the through current value in the secondary electron image of the standard sample can be made closer to the contrast of the actual contact hole having the remaining film of the same thickness. Therefore, the remaining film thickness can be more accurately evaluated.

In an actual semiconductor device,
Contact holes having various aspect ratios are provided. The contrast and the through current value of the contact hole in the secondary electron image may be different depending on the aspect ratio of the contact hole.

Therefore, in claim 12, the thickness of the resin layer is different for each standard sample for contact hole inspection. As described above, according to the twelfth aspect, the opening having the aspect ratio is formed by adjusting the thickness of the resin layer. As a result, by controlling the thickness of the resin layer, it is possible to form a plurality of types of openings having different aspect ratios using a common mask pattern.

In an actual semiconductor device,
A contact hole is formed on the wiring metal. The contrast and the through current value of the contact hole in the secondary electron image may differ depending on the presence or absence of the wiring metal on the bottom surface of the contact hole.

Therefore, a thirteenth aspect has a configuration in which a conductive film is provided between the supporting substrate and the pseudo residual film. Thus, according to the thirteenth aspect of the present invention, since the conductive film is provided, the contrast and the through current value in the secondary electron image of the standard sample can be reduced by the actual contact hole having the remaining film of the same thickness. Can be brought closer to the contrast. Therefore, the remaining film thickness can be more accurately evaluated.

By the way, when the contact hole is formed by RIE, the inside of the contact hole (bottom surface or wall surface) is formed.
Adhere to the fluorocarbon. Fluorocarbons are
Affects etching characteristics. For this reason, it is important to know the thickness of the fluorocarbon in order to obtain the optimum etching conditions.

Therefore, in claim 14, below the resin layer,
The configuration is such that a fluorocarbon film with a known thickness is provided. Thus, in the invention of claim 14, since the fluorocarbon film having a known thickness is formed under the resin layer, the fluorocarbon film thickness on the bottom surface of the contact hole can be evaluated. In addition, the thickness of the remaining film below the fluorocarbon film can be evaluated.

(Method for Manufacturing Standard Sample) According to the method for manufacturing a standard sample for contact hole inspection according to claim 15 of the present invention, a step of forming a pseudo residual film having a known film thickness on a support substrate. Forming a coating film by applying a photosensitive resin on the pseudo residual film, and selectively curing a part of the coating film to form a resin layer having an opening penetrating the resin layer And a step of performing the method.

According to the fifteenth aspect of the present invention, a pseudo residual film having a known thickness is formed on a supporting substrate.
A resin layer having an opening is formed thereon. Therefore, it is possible to easily manufacture a standard sample having the same structure as that of the remaining film having a known thickness remaining on the bottom surface of the contact hole by etching. Then, by using the manufactured standard sample, the remaining film thickness of the contact hole can be easily evaluated.

(Inspection Method) According to the contact hole inspection method of the present invention, when the contact hole inspection is performed using the contact hole inspection sample of the present invention, the contact hole inspection method is performed. The electron beam is irradiated to the opening of the sample, and the value of the secondary electron current emitted from the opening or the value of the penetrating current flowing to the support substrate immediately below the opening and the value of the pseudo residual formed on the bottom surface of the opening. Create a comparison table that associates the film thickness with the film thickness, irradiate the contact hole to be inspected with an electron beam, measure the secondary electron current or through current value emitted from the contact hole, Based on the secondary electron current value or through current value emitted from the hole,
This method evaluates the thickness of the remaining film remaining on the bottom surface of the contact hole with reference to the control table.

As described above, according to the present invention, a standard sample having a known thickness is prepared in advance without any operation for measuring the residual film thickness by the cross-sectional TEM. The remaining film thickness of the contact hole can be easily evaluated by comparing the contrast or the through current value of the secondary electron image of the portion with the contrast or the through current value of the contact hole to be inspected.

[0047]

Embodiments of the present invention will be described below with reference to the drawings. In the cross-sectional views in the drawings to be referred to, the illustration of the wall surface in front of the opening is omitted, and only the cut portion is shown. [First Embodiment] In a first embodiment, an example of a contact hole inspection standard sample, a method of manufacturing the same, and an example of an inspection method according to the present invention will also be described.

First, the configuration of the standard sample of the first embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of a main part for describing a configuration of a standard sample according to the first embodiment.
As shown in FIG. 1, the standard sample according to the first embodiment is such that a pseudo remaining film 12 having a known film thickness and a resin layer 14 obtained by curing a photosensitive resin are sequentially laminated on a support substrate 10. The resin layer 14 is provided with an opening 16 penetrating the resin layer.

The material of the supporting substrate 10 is desirably the same as the material of the supporting substrate of the semiconductor device to be inspected. In this embodiment, a single crystal silicon substrate is used as the support substrate 10. In addition, as a material of the support substrate,
In addition to single crystal silicon, for example, polysilicon, glass, quartz, or sapphire is often used.

It is desirable that the pseudo remaining film 12 is made of the same material as the remaining film of the contact hole of the semiconductor device to be inspected. In this embodiment, a silicon oxide film (SiO 2) film is formed as the pseudo remaining film 12.

It is desirable that the thickness of the resin layer be a thickness corresponding to the depth of the opening of the contact hole to be inspected. The dimensions and aspect ratio of the opening are desirably the same as those of the contact hole to be inspected. The thickness of the resin layer is, for example, several μm to 10 μm.
It is good to be about 00 μm. The diameter of the contact hole is preferably, for example, about 0.1 μm to 0.5 μm. The material and the method of forming the resin layer will be described later.

Next, a method of manufacturing a standard sample according to the first embodiment will be described with reference to FIG. (A) of FIG.
(C) is a sectional process view for illustrating the method of manufacturing the standard sample.

In manufacturing a standard sample, first, a silicon oxide film 12 having a desired film thickness is formed on a support substrate 10 whose surface has been cleaned (FIG. 2A). As a method for providing an oxide film, for example, there is a thermal oxidation method in which dry oxygen is introduced into an electric furnace to oxidize. According to this thermal oxidation method, first, the temperature of the electric furnace is maintained at a temperature of about 800 ° C. to 850 ° C., and the support substrate 10 is heated for several minutes to several tens of minutes. According to this method, a silicon oxide film having a thickness of several to several tens of
The film can be formed by controlling the film thickness with an accuracy of Å unit. In particular, the thickness of about 80 ° or less, which is the escape distance of the substance, can be easily controlled. Then, the thickness of the formed silicon oxide film is determined by measuring with a precision of Å unit by a high-precision thickness measuring means such as ellipsometry.

In forming the silicon oxide film, for example, the supporting substrate is immersed in a mixed solution of ammonium hydroxide solution and hydrogen peroxide solution or hydrochloric acid, and the oxide film is formed on the substrate surface by the reaction between hydrogen peroxide and silicon. May be formed. According to this method, since the oxide film forming temperature is much lower than the former, the oxide film thickness can be uniformly provided over the entire surface of the wafer with an accuracy of about ± 1 °.

Next, a photosensitive resin is applied on the pseudo-residual film 12 of the silicon oxide film to form a coating film 13 whose thickness is accurately controlled (FIG. 2B). For application, any suitable method such as a spin coating method may be used.

Examples of the photosensitive resin include a novolak resin, a chemically amplified resist, an acrylic resin, a rubber resin, an aliphatic conjugated diene, a carboxylic acid-containing polyamide resin, a polyvinyl phenol resin, a polyhydroxystyrene resin, and a brominated resin. Bisphenol A type epoxy resin, polycarbonate diol-modified dicarboxylic acid resin, α, β unsaturated carboxyl group-containing monomer resin, copolymer composition composed of vinylpyrrolidone and vinyl acetate, polybenzoxazole resin, polytetramethylene glycol-modified dicarboxylic acid resin It is preferable to use a photosensitive diazoquinone compound resin, a polyamic acid compound resin, or an imide resin.

Next, a part of the coating film is selectively cured to form a resin layer 14 having an opening 16 penetrating the resin layer 14 (FIG. 1C). In the curing process, first, the coating film 13 is heated to 80 ° C.
Pre-bake in a moderate temperature oven. Next, the prebaked coating film 13 is exposed to an appropriate amount of ultraviolet light. Then, the latent image generated as a result of the exposure is developed using an appropriate solvent.

At the time of exposure, a high energy beam such as an electron beam or an X-ray may be applied instead of ultraviolet rays. Since very fine patterning is performed, an antireflection agent is preferably used on the front and back surfaces of the resist.

Further, in this standard sample, a cured photosensitive resin is used as a structural body, so that its dimensional stability over a long period of time is important. Therefore, in developing the photosensitive resin, it is desirable to use a developer in which the swelling of the photosensitive resin is small. As such a developing material, for example,
TMAH (TETRA METHYL AMINE HYDRO) showing alkalinity
XIDE) solutions, tertiary and quaternary amine compounds such as choline, naphthoquinonediazide, 1-methoxy-2-propanol,
Alternatively, a surfactant may be used as necessary.

After the development, the developer is sufficiently rinsed with dichloromethane, tetrahydrofuran, n-pentane, isohexane, 3-methylpentane and neohexane, 2,3-dimethylbutane, acetone, ethyl ether or methyl lactate. I do. After the rinsing, in order to completely cure the photosensitive resin, post baking is further performed at a temperature of 120 ° C. or more to cure the photosensitive resin, and the resin layer 14 is cured.
Get.

UV hardening for irradiating high-energy ultraviolet rays (about 300 nm or less) as necessary.
Alternatively, the surface of the photosensitive resin is baked by performing a short plasma treatment to make the resin layer 14 after development into a stronger structure. In addition, the standard sample is prepared on the wafer at a time. However, the standard sample may be diced and cut into small chips as necessary, so that the sample can be placed next to the inspection target.

In order to inspect the remaining film thickness of the contact hole using the standard sample manufactured as described above, the silicon oxide film was formed by changing the thickness of the pseudo remaining film from several to several hundreds of steps in several tens of steps. A standard sample having a membrane is prepared.

The opening 16 of the contact hole inspection sample is irradiated with an electron beam, and the secondary electron current value emitted from the opening 16 and the pseudo residual film formed on the bottom of the opening 16 A comparison table is created in correspondence with the film thickness of No. 12. When creating a reference table,
For example, a standard sample of each pseudo residual film thickness is inspected in the order of the thickness, the result is recorded, and the relationship between the thickness and the secondary electron current value is determined.

Next, the contact hole to be inspected is
An electron beam is irradiated under the same conditions as the standard sample, and a secondary electron current emitted from the contact hole is measured. Then, based on the secondary electron current value emitted from the contact hole, the inspection results are compared with each other, and the thickness of the remaining film remaining on the bottom surface of the contact hole is evaluated with reference to a control table.

For example, if the inspection result obtained by applying a standard sample having a thickness of 10 mm to the inspection apparatus is equal to the inspection result obtained by measuring the inspection object, the thickness of the remaining film remaining on the bottom surface of the contact hole to be inspected is the standard sample It is possible to directly obtain a quantitative inspection result that a film having a thickness of 10 ° remains at the bottom of the contact hole. For example, in the case of an insulating residual film, the through current value during electron beam irradiation decreases in proportion to the increase in the residual film thickness.

Since these measurement and comparison operations require very high speed, it is desirable to use automatic means such as a computer. In this case, for example, the computer may select and read out the remaining film thickness corresponding to the secondary electron current value of the test sample from the reference table. Further, the computer may determine the quality of the contact hole based on the remaining film thickness.

Further, it is desirable that the standard sample be stored for calibration of the fluctuation of the apparatus. In this case, since the contrast of the secondary electron image is strongly affected by the surface condition, store the standard sample in a vacuum and at a low temperature to prevent deterioration of the photosensitive resin and oxide film and other films. Is desirable.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 4 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a second embodiment. As shown in FIG. 3, in the standard sample of the second embodiment, the pseudo remaining film 12 is provided only on a part of the support substrate 10, and the photosensitive resin is formed in the formation region and the non-formation region of the pseudo remaining film 12. Opening 16
And 16a. In this embodiment, the pseudo residual film 12 is formed on the entire surface of the support substrate 10 once, and then patterned to form the support substrate 10.
A pseudo residual film is partially left on the upper surface.

In this way, two states can be obtained for a single standard sample with and without a silicon oxide film on the bottom surface of the opening. Therefore, this embodiment is a standard sample simulating a device in which both a contact hole in which an oxide film remains on the bottom surface and a contact hole in which the oxide film on the bottom surface is removed by etching are formed. As a result, it is possible to perform a comparative inspection of the two with a single measurement. Therefore, measurement accuracy can be improved.

In a semiconductor device which is mass-produced, a contact hole may be etched cleanly or a residual film may be left depending on a location. The standard sample shown in the present embodiment is used as a standard both in a place where the contact hole is completely formed and in a place where the contact hole is not completely formed, so that a more realistic inspection result comparison can be made.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 9 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a third embodiment. As shown in FIG. 4, the standard sample of the third embodiment differs from the standard sample of the first embodiment in that the pseudo remaining film 20 is formed of a silicon nitride film instead of a silicon oxide film. Note that the configuration other than the pseudo remaining film 20 is the same as that of the first embodiment, and a detailed description thereof will be omitted.

The silicon nitride film is stronger in film quality and less hygroscopic than the silicon oxide film. Moreover,
The silicon nitride film is excellent in storage because the film does not grow due to oxygen in the air. For this reason, the pseudo residual film 20
Is formed of a silicon nitride film, the storage stability of the standard sample is improved, and the measured value can be stabilized. Note that the use of an ONO film instead of the silicon nitride film can also improve the storage stability of the standard sample.

The dielectric constant of the silicon nitride film is higher than the dielectric constant of the silicon oxide film. Therefore, a pseudo residual film thinner than the silicon oxide film can be equivalently provided by the silicon nitride film. As a result, in some cases, a standard sample corresponding to a test object having a remaining film equivalently thicker than the silicon oxide film can be formed using the silicon nitride film.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 9 is a sectional view of a main part for describing a configuration of a standard sample according to a fourth embodiment. As shown in FIG. 5, the standard sample of the fourth embodiment has the same structure as that of the second embodiment except that the pseudo residual film 20 is formed of a silicon nitride film instead of a silicon oxide film. Same as the form.

More specifically, a portion of the silicon nitride film 20 having a known thickness provided on the support substrate 10 is opened, and a contact hole 16 is provided on an exposed region of the surface of the support substrate 10. The case where the contact hole 16 is provided on the nitride film region 20 is also present in one standard sample. With such a configuration, it is possible to form two types of contact holes with and without the silicon nitride film 20 at the bottom of the contact hole in one standard sample. Therefore, it is possible to simultaneously provide a standard sample in which the silicon nitride film 20 remains and a standard sample in which the silicon nitride film has been clearly removed and in which a contact hole has been formed. For this reason, the inspection result of the inspection object can be mapped between two reference values (with and without a pseudo residual film having a known film thickness) obtained from one standard sample.

[Fifth Embodiment] Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 9 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a fifth embodiment. In the fifth embodiment, the dielectric constant of the resin layer (matching film) 22 is made equal to the dielectric constant of the contact hole formation layer to be inspected. And
The configuration other than the inspection target is the same as that of the above-described first embodiment.

The photosensitive resin has a dielectric constant of about 4 to 5.
On the other hand, the dielectric constant of a silicon oxide film, a silicon nitride film, or the like of an insulating film generally used as a material of a contact hole formation layer is smaller than this. Therefore, the dielectric constant of the resin layer 22 is adjusted to be equal to the dielectric constant of the contact hole formation layer of the semiconductor device to be inspected. To lower the dielectric constant, for example, mixing a resin containing fluorine,
Alternatively, a photosensitive resin containing fluorine in the side chain may be mixed. Further, an acrylic, silicone, or other material having a low dielectric constant may be mixed.

It is desirable that the modification for adjusting the dielectric constant can be performed within the range where the resin continues to have photosensitivity. However, when the photosensitivity of the photosensitive resin is lost, the resin layer is formed as follows. It is preferable to form an opening in the opening. First, a second photosensitive resin is further applied and patterned on the first resin (resin layer 22) for forming the contact holes. Next, the first resin layer is etched and removed using the second photosensitive resin pattern (not shown) as a mask.
Next, the second photosensitive resin pattern is removed to obtain an opening formed in the first resin.

In general, a pseudo residual film such as a silicon oxide film and a resin layer differ greatly in reactivity to a developer. Therefore, patterning of the first resin can be easily performed. As another method for lowering the dielectric constant, it is also effective to provide a fine space in the photosensitive resin to make it into a state like a foamed styrene or a hollow state to lower the apparent dielectric constant.

In this case, the electrical characteristics of the resin layer are
It is closer to the actual electrical characteristics of the contact hole formation layer. As a result, the effect of the resin layer on the secondary electrons can be made closer to the effect from the actual contact hole. Therefore, the contrast in the secondary electron image of the standard sample can be made closer to the contrast of the actual contact hole having the remaining film of the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

The dielectric constant of the resin layer can be lowered or increased in accordance with the dielectric constant of the contact hole formation layer to be inspected. In addition to the dielectric constant, it is desirable that the secondary electron emission ratio and the coefficient of thermal expansion of the resin layer be equal to the values of the actual sample.

[Sixth Embodiment] Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 13 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a sixth embodiment. In the sixth embodiment, the support substrate 1
0, an impurity diffusion layer 24 having the same impurity type and impurity concentration as the impurity diffusion layer formed on the supporting substrate to be exposed on the bottom surface of the contact hole to be inspected is provided. The configuration other than the support substrate 10 is the same as that of the first embodiment.

Generally, impurities such as boron (B), phosphorus (P) or arsenic (As) are diffused on the surface of a substrate on which devices are formed. Therefore, in the present embodiment, a diffusion layer 24 that is the same as a diffusion layer used in an actual device is formed on the surface of the support substrate 10, and a resin layer 14 having an opening 16 is formed thereon. The thickness of the diffusion layer 24 may be, for example, several nm to several μm in accordance with the inspection target.
Further, the impurity concentration of the diffusion layer 24 may be set to a value according to the inspection target.

With this configuration, even if the impurity diffusion layer is provided on the support substrate of the semiconductor device to be inspected, the contrast in the secondary electron image of the standard sample can be reduced.
The contrast can be made closer to that of an actual contact hole having a remaining film of the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

[Seventh Embodiment] Next, a seventh embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 14 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a seventh embodiment. In the seventh embodiment, the support substrate 1
0, a well 26 having the same impurity type and impurity concentration as the well formed on the support substrate to be exposed on the bottom surface of the contact hole to be inspected is provided. Further, the impurity type of the well 26 may be, for example, P, As, or B according to the inspection target. Also,
The depth of the well 26 may be, for example, several thousand to several μm in accordance with the inspection object. Also, the impurity concentration of the well 26 is preferably set to a value according to the inspection target. The configuration other than that the well 26 is provided is the same as the configuration of the first embodiment described above.

In this embodiment, the surface of the support substrate 10 is NPN
A well 26 is provided for use in forming a complementary transistor circuit for simultaneously forming a transistor and a PNP transistor. In general, a semiconductor device includes a plurality of electrically independent transistors and a circuit in which each is electrically connected. Therefore, each transistor needs to be electrically independent of each other. For this reason, a contact hole usually provided on the source, drain or gate of a transistor is used to establish electrical continuity between impurity diffusion layers and wells having different conductivity which are electrically independent from each other on the same substrate. It is often provided in.

Therefore, as in this embodiment, a contact hole structure having a plurality of impurity diffusion regions is formed to simulate a well structure, and a standard for contact hole inspection having electrical characteristics closer to those of a real device. It can be a sample. Of course, when the inspection object has a multi-well structure, the standard sample may have a multi-well structure.

With such a configuration, even in the case where a well is provided immediately below the contact hole of the supporting substrate in the semiconductor device to be inspected, the contrast in the secondary electron image of the standard sample is reduced by the remaining thickness of the same thickness. It can be made closer to the contrast of an actual contact hole having a film. As a result, the remaining film thickness can be more accurately evaluated.

[Eighth Embodiment] Next, an eighth embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 16 is a cross-sectional view of a main part for describing a configuration of a standard sample according to an eighth embodiment. In the ninth embodiment, the supporting substrate is an SOI (silicon on insulator) substrate 2
It is set to 8. The configuration other than the support substrate 28 is the same as the configuration of the above-described first embodiment.

SOI substrates have recently been employed in semiconductor devices in order to increase the speed of devices and reduce crosstalk between adjacent elements due to microfabrication. In particular, SOI substrates have been used in high-speed DRAMs and processors. I have.
The SOI substrate 28 has an insulating film 32 (here, a silicon oxide film) that electrically insulates a silicon thin film having a very thin surface called an active layer 30 in the depth direction, unlike an ordinary single crystal substrate. I have. For this reason, in an SOI substrate, no DC current flows from the front surface of the substrate to the back surface of the substrate, and the electrical characteristics are different from those of a normal substrate having no insulating film inside. In general, the type and impurity concentration of the semiconductor substrate forming the active layer 30 are largely different from those of the substrate portion below the insulating film 32, and the electrical properties thereof are generally completely different.

Therefore, in the present embodiment, the same SOI substrate as the object to be inspected is used as a support substrate, and a contact hole is formed thereon with a photosensitive resin. The active layer 3
The thickness of 0 is, for example, several thousand to several μm according to the inspection object.
It is good to be about m. Further, the thickness of the insulating film 32 is preferably set to, for example, about several thousand to several μm in accordance with the inspection target. The polarity of the supporting substrate itself is the same as that of the inspection target.
Any type of N type may be used. In addition, the impurity concentration of the supporting substrate may be, for example, 10 ¹⁴ to 10 ¹⁵ atoms /
It is good to be about ³ cm ³ . It is preferable that the impurity polarity and concentration of the insulating film, active layer, and support substrate of the SOI be the same as those of the device to be inspected and have the same thickness.

With this configuration, even when the support substrate of the semiconductor device to be inspected is an SOI substrate,
The contrast in the secondary electron image of the standard sample can be made closer to the contrast of an actual contact hole having a remaining film of the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

[Ninth Embodiment] Next, a ninth embodiment of the present invention will be described with reference to FIG. FIG.
0 is a cross-sectional view of a main part for describing the configuration of the standard sample of the ninth embodiment. The ninth embodiment has a configuration in which a back surface insulating film 34 of a silicon oxide film is provided on the back surface of the support substrate 10. The thickness of the back surface insulating film is preferably, for example, several thousand to several μm in accordance with the inspection target. In addition,
The configuration other than that the back surface insulating film 34 is provided is the same as that of the first embodiment described above.
This is the same as the configuration of the embodiment.

Generally, a semiconductor device to be measured is formed on one of two surfaces of a supporting substrate (for example, a silicon substrate). However, since the wafer itself is processed in one chamber, the same film is often formed on both sides of the wafer. The film on the back side is not originally required. For this reason, the film formed on the back surface may be removed. However, usually, a thin film structure formed by a surface process is often left as a back surface insulating film for cost reduction or intentionally.

In this case, the current caused by the electron beam applied to the front surface of the substrate by the inspection device is interrupted by the oxide film on the back surface of the substrate after passing through the substrate. For this reason, the electron beam introduced into the substrate surface does not flow as a direct current on the substrate back surface. As a result, the support substrate having the back surface insulating film has different electrical characteristics from those without the back surface insulating film. Therefore, if a standard sample without a back surface insulating film is used, the result of an inspection of a test object having a back surface insulating film may not be accurate.

Therefore, in this embodiment, the back surface insulating film 34 which is the same as the back surface insulating film provided on the device to be measured is provided on the back surface of the support substrate 10, and the structure is accurately simulated, and the difference between the two does not occur. We are devising. It is desirable that the thickness and material of the back surface insulating film 34 be the same as those of the back surface insulating film provided in the semiconductor device to be measured. In addition, some prototype devices are composed of a composite film that has not only the backside insulating film but also another conductive film below it,
In such a case, it is desirable to provide the same composite film structure on the back of the standard sample as the standard sample.

As described above, since the back surface insulating film 34 is provided on the back surface of the support substrate 10, even when the back surface insulating film is provided on the semiconductor device to be inspected, the contrast in the secondary electron image of the standard sample can be reduced. The contrast can be made closer to that of an actual contact hole having a remaining film of the same thickness. As a result, the remaining film thickness can be more accurately evaluated.

[Tenth Embodiment] Next, a tenth embodiment of the present invention will be described with reference to FIG.
FIG. 11A is a cross-sectional view of a main part for describing a configuration of a standard sample according to the tenth embodiment. FIG. 11B is a plan view of the standard sample. (A) of FIG.
Corresponds to a cutout of a portion along AA in FIG.

In the tenth embodiment, a plurality of openings 16 are arranged non-uniformly in the resin layer 14 such that the planar distribution densities of the openings 16 are different from each other. In addition,
The configuration other than the distribution of the openings 16 is the same as the first configuration described above.
This is the same as the configuration of the embodiment.

In the present embodiment, the positions of the openings 16 provided in the resin layer 14 are not uniform, but are not uniform depending on the location. In an actual device, there are few regions where contact holes are provided evenly except for an array portion in which many identical cells are arranged, such as a DRAM, and the arrangement density differs depending on the location on the device. If the arrangement density of the contact holes is different, the electric resistance generated when the electron beam irradiating the substrate during the inspection passes through the substrate varies depending on the location of the device. Therefore, depending on the arrangement density, the inspection result may be different even if the same inspection is performed.

Therefore, in this embodiment, the density at which the contact holes are formed is changed depending on the location in the standard sample so that the difference in the inspection result due to the difference in the contact hole density in the actual device can be reflected. Therefore, in an actual inspection, inspection is performed by selecting a place having a contact hole density similar to the contact hole formation density of the device to be inspected from among the standard samples.

As described above, since the openings 16 are provided with various plane distribution densities, the openings 16 having the same distribution density as the plane distribution density of the contact holes to be inspected are selected to obtain the contrast of the standard sample. Can be. as a result,
The contrast in the secondary electron image of the standard sample can be made closer to the contrast of an actual contact hole having a remaining film of the same thickness. Therefore, the remaining film thickness can be more accurately evaluated.

[Eleventh Embodiment] Next, an eleventh embodiment of the present invention will be described with reference to FIG.
FIG. 12 is an essential part cross-sectional view for explaining the configuration of the standard sample of the eleventh embodiment. In the eleventh embodiment,
The resin layer 14 has a configuration in which a plurality of openings having different aspect ratios are provided. As the aspect ratio, various values may be provided, for example, in a range of about 2 to 20. The configuration other than the aspect ratio of the opening is the same as the configuration of the first embodiment described above.
In FIG. 12, two openings 16b and 16c are representatively shown among the plurality of openings.

As the contact holes provided in the semiconductor device to be measured, there may be many contact holes having the same hole diameter like DRAM, but in general, contact holes having different hole diameters are often mixed. For example, in a circuit for generating an address for controlling a memory cell provided in the periphery, many currents having different hole diameters exist in order to allow more current to flow through a transistor in a driver portion thereof, and contact holes having different hole diameters exist. Are often mixed. Further, for example, in a logic system, since the amount of current flowing for each block is different, the hole diameters of most contact holes are different.

If the hole diameter of the contact hole is different, the amount of electron beam injected into one hole or the amount of secondary electrons emitted from the hole at the time of inspection differs. For this reason, the same inspection is not always given the same inspection result even if the same inspection is performed on the material having the same remaining insulating film at the bottom of the contact hole, and different inspection results are generally obtained.

The present embodiment is a standard sample for simulating this. In the present embodiment, since a large number of contact holes having the same remaining film thickness with various aspect ratios are prepared, the aspect ratio contact hole standard suited to the actual situation of the prototype device indicates.
A comparative inspection can be performed using the inspection result. Therefore, it is possible to perform a quantitative inspection on a sample in which contact holes having different aspect ratios are mixed, which has been practically impossible in the past.

[Twelfth Embodiment] Next, a twelfth embodiment of the present invention will be described with reference to FIG.
FIG. 13 is a fragmentary cross-sectional view for explaining the configuration of the standard sample of the twelfth embodiment. In the twelfth embodiment,
The thickness of the resin layer 14 is different for each contact hole inspection standard sample. By making the diameter of the opening formed in one standard sample different, a plurality of aspect ratios can be given to the opening. As the thickness of the resin layer, for example, various values in the range of about 0, 5 μm to 2 μm may be prepared. The configuration other than the thickness of the resin layer is the same as the configuration of the above-described eleventh embodiment. In FIG. 13, one standard sample is shown as a representative, and among the plurality of openings in the standard sample, the openings 16d and 16e are shown as a representative.

The contact holes formed in the devices actually manufactured on trial have various aspect ratios.
Further, in the present embodiment, the height of the resin layer in which the contact hole is formed is controlled to change the aspect ratio of the contact hole between the standard samples. In this manner, contact holes having various aspect ratios can be manufactured from one mask. For this reason, contact holes having various aspect ratios can be realized without producing many expensive masks. By preparing various standard samples in which the height of the photosensitive resin is changed in this way, it is possible to easily cope with samples having any aspect ratio.

[Thirteenth Embodiment] Next, a thirteenth embodiment of the present invention will be described with reference to FIG.
FIG. 14 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a thirteenth embodiment. In the thirteenth embodiment,
The configuration is such that a metal layer 36 as a conductive film is provided between the supporting substrate 10 and the pseudo remaining film 12. The thickness of the metal layer 36 is preferably, for example, about several hundred to several μm in accordance with the inspection object. The configuration other than the point that the metal layer 36 is provided is the same as the configuration of the first embodiment described above.

In the standard sample of this embodiment, a contact hole provided on a metal wiring is simulated. There is a contact hole called a via hole for establishing conduction between wiring such as metal. These via holes electrically connect upper and lower metal wirings via an insulator. The metal layer 36 is provided on the support substrate 10, and the pseudo remaining film 12 having a known thickness is provided thereon. With such a configuration, a standard sample for contact hole inspection in a multilayer wiring structure can be obtained.

The conductive material includes, for example, silicon, polysilicon, aluminum (Al), copper (C
u), tungsten (W), molybdenum (Mo), cobalt (Co), gold (Au), platinum (Pt), titanium (T
i), silicide or salicide, such as P-Si, or any other suitable material used in semiconductor manufacturing can be utilized.

As described above, since the metal layer 36 is provided, the contrast in the secondary electron image of the standard sample can be made closer to the contrast of the actual contact hole having the remaining film of the same thickness. Therefore, the remaining film thickness can be more accurately evaluated.

[Fourteenth Embodiment] Next, a fourteenth embodiment of the present invention will be described with reference to FIG.
FIG. 15 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a fourteenth embodiment. In the fourteenth embodiment,
On the metal layer 36, as a pseudo residual film, titanium nitride (Ti
N) The film 38 is provided. The thickness of the TiN film 38 is preferably, for example, several hundreds to several thousand. Note that Ti
The configuration other than the point that the N film 38 is provided is the same as the configuration of the above-described thirteenth embodiment.

In this embodiment, a TiN film, which is often provided recently, is provided on the wiring, and the opening 16 is formed thereon.
Is provided. With such a configuration, it is possible to inspect whether or not the TiN film provided on the wiring is over-etched after the formation of the multilayer wiring film contact hole by the electron beam inspection apparatus.
The TiN film is used as a diffusion prevention layer, an improvement in adhesion to an underlayer, or an antihalation layer in lithography. Further, instead of the TiN film, a SiON film may be provided so as to perform the same function.

[Fifteenth Embodiment] Next, a fifteenth embodiment of the present invention will be described with reference to FIG.
FIG. 16 is a cross-sectional view of a main part for describing a configuration of a standard sample according to a fifteenth embodiment. In the fifteenth embodiment,
A fluorocarbon film 40 having a known thickness is provided under the resin layer 14.
Is provided. The thickness of the fluorocarbon film 40 is preferably, for example, about 200 ° or less. Also,
It is desirable that a sample without the fluorocarbon film 40 be used as a standard sample. The configuration other than that the fluorocarbon film 40 is provided is the same as the configuration of the thirteenth embodiment described above.

RIE for forming contact holes
When etching is performed by using the method, a fluorocarbon polymer film having an unknown thickness is formed on the inner wall and the bottom of the contact hole. These film thicknesses govern the etching characteristics. Therefore, it is important to accurately measure the thickness.

Therefore, in this embodiment, a fluorocarbon film 40 having a known thickness is provided immediately below the resin layer 14 in order to obtain a standard sample capable of measuring the fluorocarbon polymer film thickness. That is, a metal layer 36 is provided on the support substrate 10, and a TiN film 38 and a fluorocarbon film 40 as pseudo residual films are sequentially laminated.

Then, by comparing the contrast of the standard sample corresponding to various fluorocarbon polymer film thicknesses with that of the contact hole immediately after the etching of the device to be measured by electron beam inspection, the bottom of the contact hole of the device to be inspected is compared. It is possible to measure the thickness of the fluorocarbon polymer film or the thickness of the remaining film remaining thereunder quantitatively.

It is known that the fluorocarbon polymer adheres to the inside of the contact hole after RIE even on materials other than TiN. In such a case, the fluorocarbon polymer is exposed when the inspection target is etched. It is desirable to use a standard sample having a structure in which a fluorocarbon film is provided on the material surface.

In the above-described embodiment, an example has been described in which the present invention is configured under specific conditions. However, the present invention can be variously modified. For example, in the embodiment described above, an example was described in which the pseudo residual film was formed of a specific material such as a silicon oxide film or a silicon nitride film. However, in the present invention, the material of the pseudo residual film is not limited to these. For example, as a pseudo residual film, TiN
A film, a TaN film, an ONO film, a SiON film, a SOG (spin-on-glass) film, a silica-based inorganic film, a silica-based organic film, or a ferroelectric film may be formed.

Further, as a material of the pseudo remaining film, for example, a metal used for a wiring material may be used. Examples of such a metal include titanium (Ti), tungsten (W), molybdenum (Mo), aluminum (Al),
Gold (Au), platinum (Pu), cobalt (Co) and iridium (Ir). In addition, as materials for the pseudo residual film, in addition to these, oxides of these metals, silicides, their oxides, intermetallic compounds, organic materials, oxide superconducting materials, and any other materials used in semiconductor devices Materials can be utilized.

Further, in the above-described embodiment, an example in which the pseudo residual film is formed by the thermal oxidation method has been described. However, in the present invention, the pseudo residual film may be formed by any suitable method such as a lamp annealing method. In the above-described embodiment, an example in which the secondary electron current value is detected and the contrast of the secondary electron image is compared has been described. However, in the present invention, the through current value may be compared.

In the above-described embodiments, specific materials and their combinations have been described. However, it goes without saying that any material used in the semiconductor manufacturing process can be applied without being limited to that range. . By collecting data based on a combination of these, it becomes possible to measure the film thickness in the case of a composite state in which various materials appearing in a semiconductor process are present simultaneously, for example, an oxide film and a fluorocarbon film are present simultaneously. If a material produced when the wiring material is oxidized or deteriorated by another chemical is prepared in a state where the film thickness is known and used as a standard sample, it is possible to quantitatively grasp defects such as wiring on the spot.

It is effective to use as much as possible the same structure as that of the object to be inspected as the support substrate provided with the contact holes made of photosensitive resin. If a number of the insulating films are all removed and a known thickness of insulating film is grown thereon and then a contact hole made of a photosensitive resin is provided, a more complete standard sample can be obtained.

Also, when a composite film is used as an object, the thickness of the film at the bottom of the contact hole to be inspected can be estimated by using a composite film having a known thickness as a standard.

[0126]

According to the present invention, there has been practically no practical method for measuring the remaining pressures of the contact holes, only by taking a cross-sectional TEM image of the actual device. A pseudo remaining film having a known thickness is formed, and a resin having an opening corresponding to a contact hole is provided thereon. In this manner, a standard sample having a pseudo contact hole structure having a pseudo residual film of a known thickness on the bottom surface can be easily manufactured. As a result, the amount of the remaining insulating film to be inspected can be quantitatively determined only by comparing the standard sample and the inspection object through the same electron beam inspection.

When the inspection method of the present invention is used, the time required for the cross-sectional TEM observation and the sample preparation for the observation, which are conventionally required, are not required, and the measurement of the remaining film thickness can be shortened. it can.

Therefore, it is possible to accurately measure the thickness of the remaining film remaining at the bottom of the contact hole at the site where the device is being prototyped, so that the quality of the device can be quantitatively determined. Since the inspection can be easily performed on site, it is possible to quickly know the timing of the occurrence of the device failure, and it is possible to reduce the large manufacturing loss caused conventionally.

In addition, since the inspection can be performed without using a TEM, the remaining film thickness can be quickly inspected for a large number of contact holes. In addition, since the thickness of the film remaining at the bottom of the contact hole can be quantitatively measured continuously, it is possible to detect process fluctuations up to the failure, defects in the etching equipment, etc. at an early stage, and prevent large accidents before they occur. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a first embodiment.

FIG. 2 is a sectional process view of a main part for describing a method of manufacturing a standard sample for contact hole inspection in the first embodiment.

FIG. 3 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection in a second embodiment.

FIG. 4 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a third embodiment.

FIG. 5 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a fourth embodiment.

FIG. 6 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection in a fifth embodiment.

FIG. 7 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a sixth embodiment.

FIG. 8 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a seventh embodiment.

FIG. 9 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection in an eighth embodiment.

FIG. 10 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a ninth embodiment.

FIG. 11 is a cross-sectional view of a principal part for describing a configuration of a standard sample for contact hole inspection in a tenth embodiment.

FIG. 12 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to an eleventh embodiment.

FIG. 13 is a cross-sectional view of a main part for describing a configuration of a standard sample for contact hole inspection according to a twelfth embodiment.

FIG. 14 is an essential part cross sectional view for explaining the structure of a contact hole inspection standard sample according to a thirteenth embodiment;

FIG. 15 is a cross-sectional view of a principal part for describing a configuration of a standard sample for contact hole inspection in a fourteenth embodiment.

FIG. 16 shows a contact hole according to a fifteenth embodiment.
FIG. 3 is a cross-sectional view of a main part for describing a configuration of a standard sample for inspection.
You.

FIG. 17 illustrates a configuration of a contact hole to be inspected .
FIG. 2 is a sectional view of a main part for carrying out.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Support substrate 12 Pseudo residual film (silicon oxide film) 13 Coating film 14 Resin layer 16, 16a, 16b, 16c, 16d, 16e Opening 18 Bottom surface 20 Pseudo residual film (silicon nitride film) 22 Pseudo residual film (matching film) Reference Signs List 24 diffusion layer 26 well 28 SOI substrate 30 active layer 32 insulating film 34 backside insulating film 36 metal layer 38 TiN film 40 fluorocarbon film 42 contact hole 44 bottom surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 21/768 H01L 21/302 E 21/90 C

Claims (16)

(57) [Claims] A pseudo residual film having a known thickness and a resin layer obtained by curing a photosensitive resin are sequentially laminated on a support substrate, and an opening penetrating the resin layer is formed in the resin layer. A standard sample for contact hole inspection, which is provided. 2. The standard sample for contact hole inspection according to claim 1, wherein the material of the pseudo remaining film is the same as the material of the remaining film remaining on the bottom surface of the contact hole to be inspected. 3. The standard sample for contact hole inspection according to claim 1, wherein a plane size and an aspect ratio of the opening are the same as a plane size and an aspect ratio of a contact hole to be inspected. 4. The method according to claim 1, wherein the pseudo residual film is provided only on a part of the support substrate, and openings are provided in the photosensitive resin in a region where the pseudo residual film is formed and a region where the pseudo residual film is not formed. A standard sample for contact hole inspection according to claim 1, 2 or 3. 5. The standard sample for contact hole inspection according to claim 1, wherein a dielectric constant of the resin layer is made equal to a dielectric constant of a contact hole formation layer to be inspected. 6. An impurity diffusion layer having the same impurity type and impurity concentration as the impurity diffusion layer formed on the support substrate to be exposed on the bottom surface of the contact hole to be inspected, provided on the support substrate. Claims 1, 2, 3, 4
Or a standard sample for contact hole inspection according to 5. 7. A part of the support substrate, wherein a well having the same impurity type and impurity concentration as a well formed on the support substrate to be exposed on the bottom surface of a contact hole to be inspected is provided. Terms 1, 2, 3, 4, 5
Or a standard sample for contact hole inspection according to 6. 8. The standard sample for contact hole inspection according to claim 1, wherein the support substrate is an SOI (silicon-on-insulator) substrate. 9. The standard sample for contact hole inspection according to claim 1, wherein an insulating film is provided on the back surface of said support substrate. 10. A method according to claim 1, wherein said plurality of openings are non-uniformly arranged in said resin layer so that said openings have different planar distribution densities.
A standard sample for contact hole inspection according to 6, 7, 8 or 9. 11. The resin layer according to claim 1, wherein a plurality of openings having different aspect ratios are provided in the resin layer. Standard sample for contact hole inspection. 12. The method according to claim 1, wherein the thickness of the resin layer is different for each of the contact hole inspection standard samples. 1
1. A standard sample for contact hole inspection according to 1. 13. A method according to claim 1, wherein a conductive film is provided between said supporting substrate and said pseudo remaining film.
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 1
3. Standard sample for contact hole inspection according to 3. 14. A method according to claim 1, wherein a fluorocarbon film having a known thickness is provided under said resin layer.
2. A standard sample for contact hole inspection according to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 . 15. A step of forming a pseudo residual film having a known film thickness on a supporting substrate; a step of applying a photosensitive resin on the pseudo residual film to form a coating film; Selectively curing the part to form a resin layer having an opening penetrating the resin layer . 16. In performing a contact hole inspection using the contact hole inspection sample according to claim 1, the opening of the contact hole inspection sample is irradiated with an electron beam and emitted from the opening. Create a comparison table in which the secondary electron current value or the through current value flowing to the support substrate immediately below the opening is associated with the thickness of the pseudo residual film formed on the bottom surface of the opening. Irradiating the contact hole with an electron beam
Measure the secondary current value or the through current value, based on the secondary electron current value or the through current value, refer to the control table, and determine the thickness of the remaining film remaining on the bottom surface of the contact hole. A contact hole inspection method characterized by evaluating.