JP2001093951A - Defect-inspecting semiconductor substrate, and method of inspecting semiconductor substrate and monitor for inspecting the semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a defect-inspecting semiconductor substrate facilitating detection of defects, without changing the function and constitution of an inspection unit. SOLUTION: This defect-inspecting semiconductor substrate comprises a base film 1 laid on a semiconductor substrate 13, the base film 1 is intended to raise the film surface contrast of a film forming region 22 to a no-film forming region 23 on a pattern 12 with respect to inspecting light, as compared with the contrast of the semiconductor substrate 13 surface to the film surface of the forming region 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device such as a DRAM and a method of manufacturing the same, which has improved detection sensitivity for defects (including foreign matter) generated in a pattern forming process or the like which causes device failure. The present invention relates to a semiconductor substrate for defect inspection, a method for inspecting a semiconductor substrate, and a monitor device for inspecting a semiconductor substrate.

[0002]

2. Description of the Related Art In the case of a DRAM, for example, a semiconductor device is formed by three-dimensionally forming a basic element portion such as a transistor and a capacitor and an electrical wiring connecting them in a film having a multilayer structure.

FIG. 10 is a cross-sectional view of a wafer-like semiconductor substrate on which a pattern is formed, which has been inspected by an optical defect inspection apparatus described in Japanese Patent Application Laid-Open No. 60-202949. 13 is a semiconductor substrate, 12 is a semiconductor substrate 1
3, a pattern 22 is a film surface of a film forming portion in the pattern 12, and 23 is a non-film forming portion in the pattern 12. FIGS. 11A and 11B
Is an explanatory view showing the shape of a general pattern provided on the semiconductor substrate, when the shape of each pattern is a stripe,
And a case in which circular holes are arranged.

In determining the conditions for forming a device pattern formed using the above resist film with good reproducibility so as not to cause defects by photolithography, for example, the formation of defects may be determined according to the conditions of photolithography. Inspection of the hardness is performed. In such a case, conventionally, as shown in FIG.
For example, a semiconductor substrate in which a desired device pattern 12 was formed directly on a semiconductor substrate 13 such as a Si wafer was produced, and evaluated by the optical defect inspection apparatus.

However, according to this method, the interval between patterns constituting a device becomes narrower with the increase in the degree of integration of a semiconductor substrate, and some patterns cannot be detected. However, there is a problem that a defective product is frequently generated without being able to be found.

[0006] The reason that the above-mentioned defect cannot be detected is that the defect causing the electrical failure is very fine, and the size of the defect is near the limit of the optical resolution of the inspection apparatus in many cases. Also,
It is a well-known fact that even if the defect is not fine, for example, when the thickness is thin, the difference between the optical information of the defective portion and the optical information of the normal pattern is almost eliminated, and it is difficult to detect the defect as a defect. is there. Examples of such defects include those due to fluctuations in application conditions and exposure conditions of a resist film used for photolithography, and those due to mask pattern defects inherent in an exposure mask for imprinting a device pattern.

As a method for more reliably detecting a defect present in the pattern, for example, Japanese Patent Application Laid-Open No. 61-86637 discloses a method of irradiating a wafer having a pattern with light of two or more wavelengths, A method is disclosed that detects reflected light of a pattern and makes it easier to detect a defect existing in the pattern based on a difference between the reflected lights, and irradiates light having two different wavelengths to a normal pattern and an abnormal pattern having a defect. In this way, it is intended to make it easy to detect a difference that cannot be recognized with one wavelength. According to the above method, the number of defects that can be detected can be increased as compared with the case where a wafer on which a device pattern to be inspected is formed is inspected using only one wavelength of light.

[0008]

However, detecting and managing defects on a wafer having a pattern using the above-described conventional method involves the following problems. First, even if the reflected light from the wafer on which the pattern is present is detected with light of two different wavelengths, the desired defect is not necessarily reflected at those wavelengths so that it can be judged as a defect compared to a normal pattern. That is, no difference in rate can be obtained. In such a case, even if the image pickup device has a plurality of spectral sensitivity characteristics, in order to detect a defect that does not provide contrast at any of the selected wavelengths, the configuration of the image pickup device or the like on the inspection device side should be determined according to the defect. Has to be changed, and there has been a problem that the device is large and the operability is poor, which is not practical.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor substrate for defect inspection and a method for inspecting a semiconductor substrate which can easily detect defects without changing the function or configuration of the inspection apparatus. Aim. It is another object of the present invention to provide an inspection monitor device capable of determining the detection sensitivity and the degree of defect in defect inspection.

[0010]

According to a first aspect of the present invention, there is provided a semiconductor substrate for defect inspection, comprising a semiconductor substrate and a pattern formed by arranging a film forming portion and a non-film forming portion on the semiconductor substrate. The following formula (1) for the light between the film forming portion and the non-film forming portion with respect to light: contrast value = | R2-R3 | / (R2 + R3) (1) (where R2 is the reflectance at the film forming portion and R3 Is the reflectance at the non-film-forming portion.) And a base film that makes the contrast higher than the contrast between the semiconductor substrate and the film-forming portion of the pattern.

A second defect inspection semiconductor substrate according to the present invention is the first defect inspection semiconductor substrate according to the first defect inspection semiconductor substrate, wherein the contrast between the film forming portion of the pattern and the underlying film surface with respect to irradiation light is different from that of the first substrate. Is larger than the contrast with the film forming portion.

According to a third aspect of the present invention, there is provided a semiconductor substrate for defect inspection, comprising: a semiconductor substrate; and a film forming portion for the irradiation light in a pattern in which a film forming portion and a non-film forming portion are arranged on the semiconductor substrate. (1) Contrast value = | R2-R3 | / (R2 + R3) (1) where R2 is the reflectance at the film forming portion, and R3 is the non-film forming portion. Of the semiconductor substrate and a base film that makes the contrast smaller than the contrast between the semiconductor substrate and the film forming portion of the pattern.

The fourth defect inspection semiconductor substrate according to the present invention is the third defect inspection semiconductor substrate according to the third defect inspection semiconductor substrate, wherein the contrast between the film forming portion and the non-film forming portion is different from that of the irradiation light film forming portion. The light reflected from the forming portion is small enough to be determined to be uniform.

In a first method for inspecting a semiconductor substrate according to the present invention, the inspection light is applied to any one of the first to fourth defect inspection semiconductor substrates on which a pattern is formed, and the inspection light is irradiated from the substrate of the inspection light. This is a method of detecting a defect based on a difference between the intensity distribution of the reflected light and the normal intensity distribution.

A second method for inspecting a semiconductor substrate according to the present invention is a method for adjusting the film thickness of a pattern in the first method for inspecting a semiconductor substrate.

A third method for inspecting a semiconductor substrate according to the present invention is a method for inspecting a semiconductor substrate according to the first method, wherein a pattern is formed in an insulating film.

A fourth method for inspecting a semiconductor substrate according to the present invention is the third method for inspecting a semiconductor substrate, wherein the insulating film is a silicon oxide film or a silicon nitride film.

A fifth method for inspecting a semiconductor substrate according to the present invention is the method for inspecting a semiconductor substrate according to the first aspect, wherein the pattern is a resist or an antireflection film.

A sixth method for inspecting a semiconductor substrate according to the present invention is the method for inspecting a semiconductor substrate according to any one of the first to fifth aspects, wherein the irradiation light is visible light, and the pattern or the insulating film is semi-transparent to visible light. The method of membrane.

According to a seventh method for inspecting a semiconductor substrate according to the present invention, in the method for inspecting a semiconductor substrate according to any one of the first to fifth aspects, a defect having a known size is used as a monitor.
It is a way to make it into a pattern.

A first semiconductor substrate inspection monitor device according to the present invention is a device in which a defect of a known size is formed as a monitor on any one of the first to fourth defect inspection substrates.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a sectional view showing a state in which a pattern is formed on a semiconductor substrate for defect inspection according to a first embodiment of the present invention. In the drawing, reference numeral 12 denotes a pattern, reference numeral 10 denotes a semiconductor substrate for defect inspection, and reference numeral 13 denotes a semiconductor substrate. Is provided with a base film 1 on the surface on which the pattern
Is a film forming portion of a pattern, 23 is a non-film forming portion, and the above-mentioned pattern is a film actually used for a product or a film used for determining conditions of a processing apparatus. Film.

That is, the semiconductor substrate for defect inspection according to the present embodiment has a semiconductor substrate 13 provided with a base film 1. The base film 1 is formed by forming a pattern 12 on the semiconductor substrate 10 for defect inspection according to the present embodiment. When formed, the pattern 12 has a portion 22 where a film is formed and a portion 23 where a film is not formed. The above expression (for the inspection light between the film surface of the film forming portion 22 and the non-film forming portion 23) The contrast shown in 1) is provided so as to be larger than the contrast between the surface of the semiconductor substrate 13 and the film surface of the film forming portion 22. The base film 1 is made of, for example, silicon oxide as shown in the following examples. The film structure is properly used depending on the configuration and purpose of the pattern 12 to be evaluated, such as a two-layer film of a film and a silicon nitride film or a single-layer film of a silicon nitride film.

The method of enhancing the ease of detection differs depending on the type of defect or foreign matter. However, if the contrast between the film forming portion 22 and the portion without a film, that is, the non-film forming portion 23 is maximized, the detection is easy. Often it becomes easier. In other words, the present invention is based on the fact that the contrast between the film forming portion 22 and the non-film forming 23 of the pattern is increased, and for example, a defect that a film exists in a portion where the film does not originally exist can be found with higher contrast. It is.

As described above, in the embodiment of the present invention,
Defect detection is obtained by the contrast obtained from the reflectance as described above, and is not specified by the optical resolution, and can be detected even when the thickness of the defect is small due to the increase in detection sensitivity. is there.

Incidentally, the pattern 12 is shown in the form of a concavo-convex pattern having an equal pitch as an example.
As shown in FIGS. 1A and 1B, the pattern may be a stripe pattern, a pattern in which circular holes are arranged, a pattern other than this, or a concavo-convex pattern having an even pitch. That is, any pattern may be used as long as it is a pattern composed of a portion where the film is present and a portion where the film is not present, and has a structure that can be measured by an optical inspection device used for inspection.

As the device pattern 12 to be inspected, there are a film actually used for a product and a film used for determining the conditions of a processing apparatus. This is a film whose thickness and film quality are specified. In this specification, a resist film that forms a desired device pattern by photolithography will be used as an example unless otherwise specified. There are various types of such resist films, and each of them exhibits certain optical characteristics with respect to the wavelength of visible light used for inspection by an optical defect inspection apparatus. Unless otherwise specified, the wavelength of visible light used for inspection is 545 nm, and the refractive index n is 1.5407 and the extinction coefficient k is 0.0011 for that wavelength.
A description will be given using a resist film having a value of 3 as an example.
Further, although the same resist film has a different thickness depending on the device pattern, a film having a thickness of 660 nm will be described below as an example unless otherwise specified.

Embodiment 2 In the first embodiment, the base film 1 is provided on the semiconductor substrate 13 so as to maximize the contrast between the film forming portion 22 and the non-film forming portion 23 of the pattern. However, the second embodiment of the present invention The semiconductor substrate for defect inspection described above is provided with a base film 1 so as to minimize the contrast.

That is, in the present invention, it is preferable that the contrast between the film forming portion 22 and the non-film forming portion 23 be as small as possible, as the image due to the reflection of the irradiation light approaches a uniform state. If there is a defect, the part is not in a uniform state and is clearly detected.

Embodiment 3 The method for inspecting a semiconductor substrate according to the third embodiment of the present invention includes the steps of: providing a semiconductor substrate for defect inspection according to the first or second embodiment on which a pattern is formed;
Irradiate the detection light, read the intensity distribution of the reflected light of the detection light with an optical sensor or the like, detect the change from the pattern of the normal intensity distribution, and create the pattern or pattern formed on the semiconductor substrate for defect inspection. This is an inspection method for detecting a defect of a film that has entered. That is, in the case of the first embodiment, for example, a defect is detected in a regular intensity pattern regularly arranged in black and white and black and white with a good contrast as a difference from the arrangement where the defect should be originally. Further, in the case of the second embodiment, a defective portion is detected with a different intensity from the others in a regular pattern having a uniform intensity.

If the shape does not change much even if the film thickness is slightly changed from the actual process, the contrast can be changed by adjusting the film thickness of the pattern. In other words, the reflectance can also be obtained by calculation (simulation) based on the optical theory of reflectance and transmission of a general laminated thin film, as described below.

[0032]

(Equation 1)

FIG. 3 shows an example of the calculated values (calculated results), with the abscissa plotting the resist film thickness and the ordinate plotting the reflectivity. FIG.
(A) to (c) show the results obtained by simulating the reflectance of the inspection light with respect to the change in the reflectance with respect to the resist film thickness of the semiconductor substrate on which the pattern is formed and the semiconductor substrate for defect inspection based on the above equations. FIG. 3A is a characteristic diagram when there is no conventional under film, and FIGS. 3B and 3C are characteristic diagrams when the under film of the present invention described in detail in the following examples is provided. Then, the reflectance changes as shown in the figure depending on the thickness of the film forming part 22 constituting the pattern 12. Film forming part 2
2 is represented by a solid line, and the reflectance R3 of the non-film forming portion 23 is represented by a solid line.
Is indicated by a dotted line.

FIG. 4 shows the resist film thickness on the horizontal axis and the contrast obtained from the reflectance based on the above formula on the vertical axis. FIG. 4A is a characteristic diagram without a conventional underlayer, and FIGS. 4B and 4C are contrast diagrams with respect to the resist film thickness of the semiconductor substrate for defect inspection according to the embodiment of the present invention described in detail in the following embodiments. 3 and 4, it is understood from FIGS. 3 and 4 that in the present embodiment, high contrast can be obtained in a wide range of the film thickness of the film forming portion of the pattern.
In other words, by providing the base film as in this embodiment, the above-described contrast can be increased and a high contrast can be obtained in a wide range of film thickness regions. Can also change the contrast.

As the above-mentioned pattern, there is a resist or an anti-reflection film obtained by photolithography, and in some cases, the pattern is formed via an insulating film such as a silicon oxide film or a silicon nitride film. When a visible light semi-transmissive film is used for the pattern or the insulating film and visible light is used as the detection light, a defect in the pattern or the insulating film or a defect such as the shape of the pattern can be detected.

Further, the defect detectable by the detection light is previously formed as a monitor portion in the semiconductor substrate for defect inspection according to the first or second embodiment provided with the pattern, so that the defect detection limit in the inspection of the semiconductor substrate can be improved. And the degree of defects can be quantitatively determined. Further, according to the basic function of the inspection, the semiconductor substrate for the defect inspection in which the normal pattern and the above-mentioned monitor section are formed can be used independently and repeatedly as a monitor device for the inspection sensitivity.

[0037]

[Embodiment 1] FIG. 2A is a cross-sectional view illustrating a state in which a pattern 12 of a resist film obtained by photolithography is provided on the semiconductor substrate 10 for defect inspection according to the first embodiment, and reference numeral 13 denotes a semiconductor substrate. A certain Si wafer, 1
Is a base film, and a silicon nitride film (S
i ₃ N ₄ film: The refractive index n is 1.
99, a film having an extinction coefficient k of 0) is formed to a thickness of 63 nm, and a silicon oxide film SiO ₂ (refractive index for a visible light wavelength of 545 nm) is formed thereon as a second base film 3. n is 1.44 and the extinction coefficient k is 0).
The resist film is formed with a thickness of 0 nm, and the pattern of the resist film is formed thereon.

A wavelength of 545 nm used as inspection light
For the visible light, the resist film forming the pattern 12 has a thickness of 600 nm and a refractive index n of 1.540.
7. The extinction coefficient k indicates a value of 0.00113. When the above inspection light is applied to the defect inspection semiconductor substrate 10 provided with a pattern by using an optical inspection apparatus described in JP-A-60-202949, the reflectance of the reflected light becomes 22 and the non-film forming portion 23, the reflectance of the inspection light is 1 in the pattern film forming portion 22.
7%, and 1% in 23 non-film formation portions. When the contrast value is calculated from the reflectance value by the above equation (1), 0.9 is obtained.
It becomes 4.

FIG. 3 (b) is a characteristic diagram showing the change in the reflectance with the thickness of the resist pattern obtained by the calculation (simulation) based on the optical theory of the reflectance and transmission of the above general laminated thin film. FIG. 4B is a characteristic diagram showing the change of the contrast obtained from the reflectance based on the above-mentioned formula with the thickness of the resist pattern.

Embodiment 2 FIG. In the first embodiment, FIG.
As shown in FIG. 3, a silicon nitride film 2 (SiN film: a film having a refractive index n of 1.99 and an extinction coefficient k of 0 with respect to light having a wavelength of 545 nm, a value of 0) is formed as a base film 1 on a Si wafer. A pattern is formed in the same manner as in Example 1 except that the semiconductor substrate for defect inspection according to the embodiment of the present invention in which only the thickness of 63 nm is formed is formed. The reflectance is different between the film forming portion 22 of the pattern and the non-film forming portion 23, and the reflectance of the inspection light is 14% in the film forming portion 22 of the pattern and 1% in the non-film forming portion 23. When the contrast value is calculated from the reflectance value by the above equation (1), it is 0.89. FIG. 3 is a characteristic diagram showing, as in the first embodiment, the change in the reflectance of the general laminated thin film with the thickness of the resist pattern obtained by calculation (simulation) based on the optical theory of the reflectance and transmission.
FIG. 4C is a characteristic diagram showing a change in the contrast of the resist pattern with the film thickness of the resist pattern based on the reflectance based on the above equation.

Comparative Example 1 In the first embodiment, FIG.
A semiconductor substrate 13 having a device pattern 12 formed thereon is inspected in the same manner as in the first embodiment except that a conventional semiconductor substrate shown in FIG. Substrate 1
3, the reflectance of the reflected light is different between the film forming part 22 of the pattern and the non-film forming part 23, and the reflectance of the inspection light is 11% in the film forming part 22 of the pattern and the reflectance of the non-film forming part 23 is 11%.
The percentage is 37%. When the contrast value is calculated from the reflectance value by the above equation (1), it is 0.54. Further, as in the case of Example 1, a characteristic diagram showing a change in the reflectance with the thickness of the resist pattern of the reflectance obtained by calculation (simulation) based on the optical theory of the reflectance and transmission of the above general laminated thin film is shown in FIG. FIG. 4A shows a characteristic diagram showing a change in the contrast of the resist pattern depending on the film thickness based on the reflectance based on the above equation. Note that the Si wafer has a refractive index n of 4.10 for light having a wavelength of 545 nm,
The extinction coefficient k is calculated as 0.0418 (see FIG. 3).
(A)).

According to the first and second embodiments and the first comparative example, as shown in FIG.
The film structure may be properly used according to the configuration and purpose of the pattern 12 to be evaluated, such as a two-layer film 2a of FIG. 2 and a silicon nitride film 2 and a single-layer film 2b of a silicon nitride film. In this case, the difference in reflectance between the structures is as shown in FIG.
As shown in FIG. 4C, the contrast values are shown in FIGS.
As shown in FIG. 4A, when there is no underlayer of the conventional example,
It can be seen that the contrast value can be significantly increased in each case as compared with the case of FIG.

Embodiment 3 FIG. In Example 1, the inspection light was applied in the same manner as in Example 1 except that the pattern was as shown in FIG. That is, the pattern according to the present embodiment is a pattern 25a in which a film is partially present in a portion where a film is originally not present and a pattern 24a in which a film is lacking in a portion where the film should be originally, and a top view of the pattern is shown in FIG. ) Shows A- in FIG.
FIG. 5B is a cross-sectional view taken along the line A ′. FIG. 5 (a), (b)
In the case where the film forming portion 22 and the non-film forming portion 23 are arranged side by side, if there is a defect in the portion 24a where the film is partially missing or a defect in the portion 25a where the film is partially left, the film forming portion When the contrast between the film and the non-film forming portion is large, the above-described defect can be emphasized, and the detection becomes easier than in the conventional case. In fact, FIG.
As for the pattern defects as shown in (1), the range of defects that can be detected has also been increased. That is, while the contrast value is 0.54 in the comparative example 1, the contrast value is 0.94 in the present embodiment, so that the defects 24a, 2a
5a becomes easier to detect.

Embodiment 4 FIG. A description will be given below by evaluating how easy it is to detect a defect in the present embodiment compared to the comparative example in a device pattern in which a defect is experimentally formed.
In Example 1, the pattern was formed using the hole pattern shown in FIG. FIG. 6A is a top view showing a state in which a pattern is provided on the semiconductor substrate for defect inspection according to the embodiment of the present invention, and FIG. 6B is a cross-sectional view taken along line BB ′ in FIG. The defect 24b indicates a defect having a larger hole diameter than the normal pattern, and the defect 25b indicates a defect having a smaller hole diameter than the normal pattern.

FIG. 7 is an explanatory view for explaining an evaluation result showing a change in a detection rate due to a deviation amount of an inner diameter of a hole constituting a pattern from a reference. In FIG. The hole pattern shown in FIG. 6 is provided on the original semiconductor substrate 13 of FIG. As is clear from the figure, the detection rate of this example is higher than that of the comparative example for any small amount. In the case of this hole pattern, the value to be managed as a defect in this device pattern is determined. Is ±
Although it is 50 nm, it can be understood that this value cannot be managed in the conventional example, but can be managed in the present embodiment.

As shown in the results of FIG. 7, the present embodiment is used to remove the defects shown in the examples of FIGS. 5 and 6 by gradually changing the size of the defects themselves. By producing an evaluation sample in which a defect is formed, it is possible to manage whether or not a defect of a level desired to be managed as a device pattern has occurred. Examples of a method of forming such a defect include a method of adding or modifying a mask used for resist exposure to drop or bury a pattern, and a method of directly modifying a sample in which holes or wirings are patterned.

It is needless to say that any other structure or a different material may be used as the underlayer as long as the structure can provide the contrast as shown in Examples 1 to 4. Nor. For example, a single layer film such as a Si film, a silicon oxide film, a TiN film, a Ti film, and an Al film may be used depending on the purpose, and these films may be replaced with each other or with a silicon nitride film or a silicon oxide film. And a multi-layer structure in combination with the above. In this case, it is possible to obtain the reflectance of the film forming portion 22 and the non-film forming portion 23 of the pattern by the above numerical simulation using the complex refractive index of the film with respect to the wavelength of the visible light used for the inspection. Using a simulation, it is possible to design an optimal underlayer structure for inspection.

In this embodiment, the method of inspecting the pattern of the resist film has been described. However, other films can be inspected in the same manner as in this embodiment. The membrane structure can also be inspected. Also in this case, as shown in FIG. 4 in this embodiment, the reflection of the portion 22 with the film to be inspected and the portion 23 without the film to be inspected using the complex refractive index of the film with respect to the wavelength of visible light used for the inspection. By calculating the ratio in advance, it is possible to design which base film is effective for a desired film structure. In addition, actual defect management can be performed by preparing an evaluation sample in which a pattern is formed as shown in FIGS.

In the above embodiment, a silicon substrate is used as the semiconductor substrate 13.
In addition to a silicon substrate, an SOI substrate or a compound such as Ga
A substrate of As or InP or an oxide glass substrate may be used. The target devices are silicon devices, Ga devices.
As devices or TFTs may be used. Further, even when such a substrate is used, as shown in FIG. 4 in the above embodiment, the portion where the film to be inspected is used by using the complex refractive index and the like of the film and the substrate with respect to the wavelength of visible light used for inspection. It is possible to obtain the reflectance of the portion 23 having no film to be inspected by numerical simulation, and it is possible to design the optimal underlayer structure for inspection using this numerical simulation.

Also, without changing the pattern of the resist film,
For example, if the shape does not change much even if the film thickness is slightly changed from the actual process, the structure of the film 21 to be intentionally evaluated, that is, the structure is changed to a contrast value by changing the resist film thickness here. May be increased. For example, as shown in FIG.
If the evaluation is made slightly shifted from m to 630 nm, the contrast value can be increased to 0.90, and the possibility of improving the ease of detecting a defect increases.

Comparative Example 2 FIG. 8 is a cross-sectional view of a conventional semiconductor substrate 13 in which a wiring pattern is formed with a polysilicon film via a silicon nitride film as an insulating film, and 30 is a crack. The case will be described. That is, as shown in FIG. 8, a silicon nitride film (Si ₃ N ₄ film) 26
A wafer in which a polysilicon film 22 was formed thereon with a thickness of 100 nm and the polysilicon film 22 was patterned as shown in FIG. 8 was used. Here, the film thickness of the silicon nitride film and the polysilicon film is a film thickness used in an actual device structure. For example, a case where a defect to be evaluated in this inspection is a crack 30 generated in the insulating film 26 will be described. Since the crack is a linear defect having a very large depth, light does not reach the crack bottom, and the reflectance of the defective portion is 0%.

When this wafer was inspected with visible light having a wavelength of 545 nm, the reflectance on the wiring 22 (polysilicon film surface) was 51.8%, and the reflectance on the wiring 23 (silicon nitride film surface) was 0.7. %become. From this reflectivity, the contrast value above and below the wiring is 0.97, which is a very contrasting state. However, despite the high contrast value, the reflectance of the crack portion 30 to be recognized as a defect and the reflectance of the wiring lower portion 23 are extremely close to each other.
If there is a crack 30 that is recognized as being even blacker than 3, it is difficult to detect the crack.

Embodiment 5 FIG. FIG. 9 is a sectional view of a semiconductor substrate for defect inspection according to the embodiment of the present invention on which a pattern is formed.
The only difference is that a silicon oxide film having a thickness of 236 nm is formed as the base film 1 between the insulating film 26 and the silicon substrate 13. When the above substrate is inspected with visible light having a wavelength of 545 nm, the wiring 22 (polysilicon film surface)
Is 38.5%, and the reflectivity under the wiring 23 (the surface of the silicon nitride film) is 39.3%. From this reflectivity, the contrast value between the wiring 22 (polysilicon film surface) and the wiring 23 (silicon nitride film surface) is 0.01, which is recognized as an image having almost no contrast. However, also in this case, the reflectance of the defective portion 30 which is a crack is 0.
% Remains.

That is, when the comparative example 2 and this embodiment are compared,
As in this embodiment, on the wiring 22 (polysilicon film surface)
It can be seen that, when the contrast value of the lower part of the wiring 23 (the surface of the silicon nitride film) is made smaller, the crack 30 having the reflectance of 0% under the wiring 23 can be recognized black, and the detection becomes easier. Although cracks have been described as an example here, in the case of a defect or a foreign substance that is always recognized as black, the fifth embodiment can provide an effect that is easier to detect than the first embodiment.

That is, since the method of increasing the ease of detection differs depending on the type of defect, it is necessary to appropriately select and use the semiconductor substrate for defect inspection according to the first or second embodiment of the present invention. is there.

[0056]

According to the first aspect of the present invention, there is provided a semiconductor substrate for defect inspection, comprising: a semiconductor substrate; and a film forming portion and a non-film forming portion disposed on the semiconductor substrate. Equation (1) Contrast value = | R2-R3 | / (R2 + R3) (1) where R2 is the reflectance at the film forming part, and R3 is the non-film forming part And a base film that makes the contrast shown by the formula (1) larger than the contrast between the semiconductor substrate and the film forming portion of the pattern. Has an effect that a semiconductor substrate for defect inspection which can easily detect the defect can be obtained.

The second semiconductor substrate for defect inspection according to the present invention comprises:
In the first defect inspection semiconductor substrate, the contrast between the film formation portion of the pattern and the base film surface with respect to the irradiation light is larger than the contrast between the semiconductor substrate and the film formation portion of the pattern. In addition, there is an effect that a semiconductor substrate for defect inspection that can easily detect defects can be obtained.

A third semiconductor substrate for defect inspection according to the present invention comprises:
In a semiconductor substrate and a pattern formed by arranging a film-forming portion and a non-film-forming portion on the semiconductor substrate, the following expression (1) between the film-forming portion and the non-film-forming portion with respect to irradiation light: contrast value = | R2 −R3 | / (R2 + R3) (1) (where R2 is the reflectance at the film-forming portion and R3 is the reflectance at the non-film-forming portion). A base film for making the contrast smaller than that of the pattern film formation portion, and has an effect that a defect inspection semiconductor substrate capable of easily detecting defects can be obtained without changing the inspection apparatus. .

The fourth defect inspection semiconductor substrate of the present invention comprises:
In the third defect inspection semiconductor substrate, the contrast between the film forming portion and the non-film forming portion is small enough that the reflected light of the irradiation light from the film forming portion and the non-film forming portion can be determined to be uniform. Further, there is an effect that a semiconductor substrate for defect inspection which can easily detect defects can be obtained without changing the inspection apparatus.

The first method for inspecting a semiconductor substrate according to the present invention comprises:
Inspection light is applied to any of the first to fourth defect inspection semiconductor substrates on which the pattern is formed, and the defect distribution is caused by a difference between the intensity distribution of the inspection light reflected from the substrate and the normal intensity distribution. This method has an effect that the defect can be easily detected without changing the inspection apparatus.

The second method for inspecting a semiconductor substrate according to the present invention comprises:
In the first method for inspecting a semiconductor substrate, the method for adjusting the film thickness of the pattern has an effect that the defect can be easily detected without changing the inspection apparatus.

The third method for inspecting a semiconductor substrate according to the present invention comprises:
In the first method for inspecting a semiconductor substrate, a method in which a pattern is formed in an insulating film has an effect that a defect of an insulating film can be easily detected without changing an inspection device.

The fourth method for inspecting a semiconductor substrate according to the present invention comprises:
In the third method for inspecting a semiconductor substrate, the insulating film may be a silicon oxide film or a silicon nitride film, and the defect of the insulating film may be easily detected without changing the inspection apparatus. There is.

A fifth method for inspecting a semiconductor substrate according to the present invention
In the first method for inspecting a semiconductor substrate, there is an effect that a defect can be easily detected by a method using a resist or an antireflection film without changing an inspection apparatus.

According to a sixth method for inspecting a semiconductor substrate of the present invention,
In any of the first to fifth methods for inspecting a semiconductor substrate, the inspection apparatus may be configured to inspect the pattern or the insulating film for defects in the pattern or the insulating film by a method in which the irradiation light is visible light and the pattern or the insulating film is a semi-transparent visible light film. There is an effect that detection can be easily performed without changing.

According to a seventh method for inspecting a semiconductor substrate of the present invention,
In any one of the first to fifth methods for inspecting a semiconductor substrate, it is possible to determine the detection sensitivity of the defect inspection and the degree of the defect by a method of forming a defect of a known size as a monitor into a pattern, There is an effect that it is possible to evaluate and manage an in-line process that causes a minute defect.

The first monitor apparatus for inspecting a semiconductor substrate of the present invention is one in which a defect of a known size is formed as a monitor on any one of the above-described first to fourth defect inspection substrates. It is possible to determine the detection sensitivity and the degree of defects, and to evaluate and manage an in-line process that causes the generation of minute defects.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a pattern is formed on a semiconductor substrate for defect inspection according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a state in which a pattern is provided on the semiconductor substrate for defect inspection according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a change in reflectance with respect to a resist film thickness of a semiconductor substrate for defect inspection according to an example of the present invention and a semiconductor substrate according to a comparative example.

FIG. 4 is a characteristic diagram showing a change in contrast with respect to a resist film thickness of a semiconductor substrate for defect inspection according to an example of the present invention on which a pattern is formed and a semiconductor substrate of a comparative example.

5A and 5B are a top view and a cross-sectional view showing a state where a pattern is formed on the semiconductor substrate for defect detection of the present invention.

FIG. 6 is a top view and a cross-sectional view showing a state where a pattern is formed on the semiconductor substrate for defect detection of the present invention.

FIG. 7 is an explanatory diagram for explaining an evaluation result showing a change in a detection rate due to a deviation amount of an inner diameter of a hole constituting a pattern from a reference by comparing an embodiment with a conventional example.

FIG. 8 is a cross-sectional view of a conventional semiconductor substrate on which a wiring pattern is formed via a silicon nitride film as an insulating film.

FIG. 9 is a cross-sectional view of a semiconductor substrate for defect inspection according to the present invention in which a wiring pattern is formed via a silicon nitride film as an insulating film.

FIG. 10 is a cross-sectional view of a semiconductor substrate on which a conventional pattern is formed.

FIG. 11 is an explanatory view showing the shape of a general pattern provided on a semiconductor substrate.

[Explanation of symbols]

Reference Signs List 1 base film, 10 semiconductor substrate for defect inspection, 12 patterns, 13 semiconductor substrate, 22 film forming portion, 23 non-film forming, 26 insulating film.

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Kazuhiro Oka 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Hiroyuki Ishii 2-3-2 Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Yoko Miyazaki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2G051 AA51 AB01 AB02 BA20 CA02 CB01 4M106 AA08 AA10 AA11 AA13 AB07 AB17 AC02 CA19 CA39 CA41 DB07 DB30 DH12 DH31 DJ17 DJ18 DJ20

Claims (12)

[Claims] In a semiconductor substrate and a pattern in which a film forming portion and a non-film forming portion are arranged on the semiconductor substrate,
The following expression (1) contrast value between the film forming portion and the non-film forming portion with respect to irradiation light = | R2-R3 | / (R2 + R3) (1) (where R2 is the reflectance at the film forming portion, R3 is the reflectivity at the non-film forming portion.) A defect inspection semiconductor substrate including a base film that makes the contrast shown by the following formula larger than the contrast between the semiconductor substrate and the film forming portion of the pattern. . 2. The defect inspection device according to claim 1, wherein the contrast between the pattern film forming portion and the base film surface with respect to the irradiation light is larger than the contrast between the semiconductor substrate and the pattern film forming portion. Semiconductor substrate. 3. A semiconductor substrate and a pattern comprising a film forming portion and a non-film forming portion disposed on the semiconductor substrate.
The following expression (1) contrast value between the film forming portion and the non-film forming portion with respect to irradiation light = | R2-R3 | / (R2 + R3) (1) (where R2 is the reflectance at the film forming portion, R3 is a reflectance at the non-film forming portion.) A defect inspection semiconductor substrate including a base film that makes the contrast shown by the following formula smaller than the contrast between the semiconductor substrate and the pattern film forming portion. 4. The contrast between the film-forming portion and the non-film-forming portion is small enough that the reflected light of the irradiation light from the film-forming portion and the non-film-forming portion can be determined to be uniform. The semiconductor substrate for defect inspection according to 1. 5. The semiconductor substrate for defect inspection according to claim 1, wherein said pattern is formed, and said semiconductor substrate for defect inspection is irradiated with inspection light. Inspection method for detecting a defect based on a difference from the intensity distribution of the semiconductor substrate. 6. The method according to claim 5, wherein the thickness of the pattern is adjusted. 7. The method according to claim 5, wherein the pattern is formed in the insulating film. 8. The method according to claim 7, wherein the insulating film is a silicon oxide film or a silicon nitride film. 9. The method according to claim 5, wherein the pattern is a resist or an anti-reflection film. 10. The irradiation light is visible light, and the pattern or the insulating film is a visible light semi-transmissive film.
A method for inspecting a semiconductor substrate according to claim 9. 11. The method according to claim 5, wherein a defect having a known size is formed as a monitor in a pattern. 12. A monitor device for inspecting a semiconductor substrate, wherein a defect of a known size is formed as a monitor on the semiconductor substrate for defect inspection according to claim 1.