JPH10173017A - Reference wafer for measuring dust particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reference sample for obtaining a detection limit of the dust in or beneath a film at a certain depth of the sample surface by providing micro-protrusions to be measured to obtain the dust detection limit on a flat semiconductor substrate. SOLUTION: On an Si semiconductor substrate 10, Si micro-protrusions 10a are formed and unified with the substrate 10, and entire surface of each microprotrusion 10a is covered with e.g. a silicon oxide insulation film 20 to be a test layer. About reference wafers having various sizes of protrusions 10a, whether their protrusions 10a can be detected is examined to obtain the detection limit of the dust in or beneath the test film 20. Depending on the type and thicknesses of the test films 20, the size of the swell of the protrusion 10a varies, and hence they can be used as a reference sample about various type and thicknesses of films in their detecting conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a standard wafer for calibration when measuring particles attached to a silicon wafer in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, it is necessary to obtain information such as adhesion and contamination of dust particles on a semiconductor substrate surface and an element surface formed on the substrate, and impurities and contamination in a certain depth direction. Is indispensable in the wafer process, and various devices are applied for that purpose.

As a method of analyzing the state of a semiconductor surface or a bulk as described above, there is a method of irradiating a sample surface with ions or electrons and measuring the responsive ions, electrons or X-rays.

Further, the wafer surface is irradiated with intense light such as laser light, and scattered light from fine particles adhering to the wafer surface is sensed from a different angle by a light receiving element or a photomultiplier tube, etc. There is a method of measuring particles attached to a surface, which measures the size, number, density distribution, etc. of foreign matter and fine particles on the wafer surface as a pulse.

[0005] In the above-mentioned method of measuring particles adhered to a surface, conventionally, PSL (polystant) has been used as a standard particle for calibrating the apparatus.
yrene latex) particles were used. PSL particles are particles having a particle size very close to monodisperse, and those having various particle sizes are commercially available. For example, by applying PSL particles having various particle diameters to the surface of a flat sample wafer and checking the detection limit of scattered light on the surface, the detection limit of the size of the attached fine particles on the sample wafer can be checked.

[0006]

By the way, the above PS
According to the conventional method of calibrating the apparatus using L particles as standard particles, the PSL particles exist only on the surface of the sample due to the method of applying the PSL particles to the surface of the sample. Detection limit of the size of dust particles attached to the sample surface,
That is, the resolution of the apparatus for the size of the dust particles attached to the sample surface is the size of the PSL particles at the detection limit. However, for particles at a certain depth from the surface of the sample wafer, the detection limit of the size and the resolution of the apparatus were unknown.

[0007] Pattern defects are induced not only by dust particles on the film but also by dust particles in and under the film. However, it was not possible to confirm whether dust particles in the film or under the film, which were located at a certain depth from the sample surface, were detected even though their management was important.

A certain depth direction from the sample surface,
As a method of obtaining the detection limit of the size of the dust particles in or under the film, PSL particles are coated on a bare silicon substrate on which no semiconductor elements or the like are formed, and the PSL is further applied.
There is also a method of preparing a standard sample having PSL particles in a lower layer such as a CVD film by coating a L material and applying a resist material, or depositing an insulating material or a metal material by CVD or the like. Putting the sample coated with the compound into the CVD / diffusion furnace / coater cannot be easily performed because the CVD / diffusion furnace / coater may be contaminated with PSL particles.

The present invention has been made in view of the above problems, and does not contaminate a CVD / diffusion furnace / coater.
An object of the present invention is to provide a standard wafer for dust particle measurement, which is a standard sample for obtaining a detection limit of dust particles in or under a film, which is located in a certain depth direction from the sample surface.

[0010]

In order to achieve the above object, a standard wafer for measuring dust particles according to the present invention is provided on a flat semiconductor substrate. A minute projection is provided as a measurement target when measuring the detection limit of the particle size.

The minute projections of the standard wafer for measuring dust particles according to the present invention correspond to the conventional PSL particles. These fine projections are covered, and a resist film is coated on the upper layer, or an insulating material is formed. By depositing a metal material or the like by CVD or the like, a standard sample having a projection under the test film such as a CVD film is obtained. If the detection limit of the size of the protrusion on the lower side of the test film is checked, the detection limit in the test film is larger than that, and as a result, the detection limit in the test film can be checked.

[0012] The standard wafer for measuring dust particles of the present invention comprises:
Since no PSL particles are applied, there is no contamination of the CVD / diffusion furnace / coater.

The material having the minute projections can be selected from the same material as the semiconductor substrate and from a different material.

In the case where the minute projections are made of the same material as the semiconductor substrate, a resist material is patterned on the semiconductor substrate in accordance with the diameter of the target projection, and the resist material is patterned by the height of the target projection. The target protrusion can be formed on the semiconductor substrate by a simple process of etching only.

When the minute projection is made of a material different from that of the semiconductor substrate, the material of the projection is deposited on the semiconductor substrate according to the height of the intended projection by CVD or the like.
Further, the resist material is patterned on the CVD film in accordance with the diameter of the target protrusion, and etching is performed until the semiconductor substrate is exposed, whereby the target protrusion can be formed on the semiconductor substrate. Although the number of steps is larger than when the minute projections are made of the same material as the semiconductor substrate, by selecting various materials for the projections,
The refractive index, transmittance, reflectance, and the like of the light of the projection can be changed, and more detailed information can be obtained.

The minute projections are formed on the semiconductor substrate by 200
It is preferable to be provided with a density of 0 to 3000 pieces / 6 mmφ. If the density of the projections is too low, the S / N ratio will deteriorate, and the interval between the projections will be required to be more than a certain level in order to correctly detect the projections. A density region of 6 mmφ is preferred.

The size of the minute projection is 0.152 in diameter.
It is preferable that the height is 0.1 to 3.0 μm and the height is 0.152 to 3.0 μm. The projection is formed by dust particles, and preferably has a size close to that of the dust particles.
The size of dust particles to be controlled, which may be a problem in production, is, for example, about 1.0 μm in diameter, and the diameter of conventionally used PSL particles is 0.152 to 3.0 μm. Therefore, the preferable range of the size of the projection is 0.15 in diameter.
The height is 2 to 3.0 μm and the height is 0.152 to 3.0 μm.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a standard wafer for measuring dust particles according to the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1D is a sectional view of a standard wafer for measuring dust particles according to the present embodiment. On the semiconductor substrate 10, minute projections 10a made of the same silicon as the semiconductor substrate are formed integrally with the semiconductor substrate. The size of the projection 10a is, for example, a diameter a of 1.0 μm and a height b of 1.0 μm.
The protrusions 10a of that size are formed on the semiconductor substrate 10 at a density of, for example, 2500 // 6 mmφ, but a desired size and density can be selected, and a preferable size is provided. The range is from 0.152 to diameter a
3.0 μm, height b is 0.152 to 3.0 μm,
Standard wafers having protrusions of various sizes can be made. Further, the preferable range of the density of the protrusion is 2000 to 2000.
3000 pieces / 6 mmφ.

As shown in FIG. 1 (e), the standard wafer for measuring dust particles of the present embodiment covers the protrusions and deposits an insulating film 20 made of, for example, silicon oxide as a test layer on the entire surface. . A strong light such as a laser beam is irradiated from above, and the scattered light is sensed by a light receiving element or a photomultiplier tube from another angle, and the size, number, density distribution, etc. of the protrusions are obtained as electric pulses. Can be. The detection limit of dust particles in and under the test film can be checked by checking whether or not the protrusions can be detected for the standard wafer having protrusions of various sizes.

The test layer covering the protrusions may be any material used in the semiconductor manufacturing process, such as an insulator such as silicon oxide or silicon nitride, a resist film, or a conductor such as polysilicon or metal. can do. If the film type or film thickness of the test film changes, the size (diameter c and height d) of the protruding portion on the protrusion changes, so that different detection limits under each condition can be examined. Each film type and film thickness within the conditions can be used as a standard sample.

Since the standard wafer for measuring dust particles of the present embodiment is not coated with PSL particles, the standard wafer for measuring dust particles is located at a certain depth from the sample surface without contaminating the CVD / diffusion furnace / coater. It can be used as a standard sample for obtaining the detection limit of dust particles inside or below the membrane.

Further, by removing the test film deposited on the standard wafer for measuring dust particles, a different test layer can be deposited once again, and this layer can be used any number of times by repeating this process.

Next, a method of manufacturing a standard wafer for measuring dust particles according to the present embodiment will be described. First, as shown in FIG. 1A, a bare semiconductor substrate 10 that has not been processed
Prepare Next, as shown in FIG. 1B, a resist film R is patterned on the semiconductor substrate 10 according to a desired diameter of the projection.

Next, as shown in FIG. 1C, for example, reactive ion etching is performed along the resist film R, and when the desired height of the protrusion is obtained, the etching is terminated. Is formed. Next, as shown in FIG. 1D, by removing the resist film R, a standard wafer for measuring dust particles of this embodiment is completed.

In the method of manufacturing a standard wafer for measuring dust particles according to the present embodiment, a resist material is patterned on a semiconductor substrate in accordance with the diameter of a target projection, and the resist material is patterned by the height of the target projection. By a simple process of etching, a projection having a desired size and density can be formed on a semiconductor substrate.

Second Embodiment FIG. 2E shows a cross-sectional view of a standard wafer for measuring dust particles according to this embodiment. On the semiconductor substrate 10, a minute projection 21a made of a material different from that of the semiconductor substrate, for example, made of silicon oxide, is formed on the semiconductor substrate. The size and density of the protrusion 21a are formed in the same manner as the protrusion of the first embodiment.

Next, a method of manufacturing the standard wafer for measuring dust particles of this embodiment will be described. First, as shown in FIG. 2A, a bare semiconductor substrate 10 that has not been processed
Prepare Next, as shown in FIG. 2B, for example, silicon oxide is deposited by CVD, and the projection insulating film 21 is formed.
To form

Next, as shown in FIG. 2C, a resist film R is patterned on the projection insulating film 21 in accordance with a desired diameter of the projection. Next, as shown in FIG. 2D, for example, reactive ion etching is performed along the resist film R, and when the semiconductor substrate 10 is exposed, the etching is terminated to form, for example, a columnar protrusion 21a. Next, as shown in FIG. 2E, the resist film R is removed to complete the standard wafer for dust particle measurement of the present embodiment.

The protrusions of the standard wafer for measuring dust particles of the present embodiment are made of a different material from the protrusions of the standard wafer for measuring dust particles of the first embodiment. In addition, an insulator such as silicon nitride, a conductor such as polysilicon or metal, or the like can be used. By changing the material of the projections in this way, it is possible to change the reflectance, refractive index, and transmittance of the projections with respect to light, and by observing these in a composite manner, dust particles in and under the film can be observed. More detailed information can be obtained. Specifically, for example, in a CVD process that is used many times in a semiconductor process and a film formation target is different from each other, the detection limit is checked for each material that is likely to become dust in the CVD apparatus, and thereby the dust count in each CVD process is determined. Data accuracy can be improved.

As described above, according to the standard wafer for measuring dust particles of the present invention, since the PSL particles are not applied, the contamination does not contaminate the CVD / diffusion furnace / coater.
It can be used as a standard sample to obtain the detection limit of the size of dust particles in the film or below the film at a certain depth direction from the sample surface. Management can be performed.

The standard wafer for measuring dust particles of the present invention of the present invention is not limited to the above embodiment. For example, the etching for forming the thick protrusion may be anisotropic etching other than reactive ion etching or isotropic etching. In the case where the protrusion is formed of a material different from that of the semiconductor substrate, the protrusion insulating film having a single-layer structure is formed. However, the protrusion may be a conductive layer, or may be a laminate of an insulating film and a conductive layer. . Further, the shape of the projection is not limited to a columnar shape, and may take various shapes such as a rectangular parallelepiped shape or a truncated cone shape in which the cross-sectional area increases as going downward. Further, the size of the projection is 0.152 to 3.0 μm in diameter and 0.152 to 3.0 μm in height.
However, in the future, when manufacturing a semiconductor device having a finer structure, it is necessary to control finer dust particles. In this case, for example, a projection having a diameter and a height of 0.1 μm or less should be used. Can be. In addition, various changes can be made without departing from the gist of the present invention.

[0033]

The standard wafer for measuring dust particles according to the present invention can be used without contaminating the CVD / diffusion furnace / coater.
It can be used as a standard sample for obtaining the detection limit of dust particles in the film or below the film at a certain depth direction from the sample surface, so that dust particles in the film or below the film can be appropriately controlled. It can be carried out.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a standard wafer for measuring dust particles according to a first embodiment of the present invention, (a) is a cross-sectional view of a semiconductor substrate, and (b) is a resist forming process. (C) shows up to the etching step, (d) shows up to the resist removal step, and (e) shows the step up to the step of covering the protrusion and depositing an insulating film.

2A and 2B are cross-sectional views illustrating a manufacturing process of a standard wafer for measuring dust particles according to a second embodiment of the present invention, wherein FIG. 2A is a cross-sectional view of a semiconductor substrate, and FIG. Until the step of depositing the insulating film, (c) until the step of forming the resist,
(D) shows up to the etching step and (e) the resist removal step.

[Explanation of symbols]

Reference numeral 10: semiconductor substrate, 10a: protrusion, 20,... Insulating film,
21: Projection insulating film, 21a: Projection, R: Resist

Claims (5)

[Claims] A fine projection is provided on a flat semiconductor substrate as a measurement target when measuring a detection limit of the size of dust particles present under a test film formed on an upper layer side. Standard wafer for dust particle measurement. 2. The standard wafer for measuring dust particles according to claim 1, wherein the minute projections are made of the same material as the semiconductor substrate. 3. The standard wafer for measuring dust particles according to claim 1, wherein said minute projections are made of a material different from a semiconductor substrate. 4. The semiconductor device according to claim 1, wherein said minute projections are formed on a semiconductor substrate.
2. The method according to claim 1, wherein the density is 0 to 3000 pieces / 6 mm.
A standard wafer for measuring dust particles as described in the above. 5. The small projection has a diameter of 0.152.
The standard wafer for measuring dust particles according to claim 1, wherein the standard wafer has a height of 0.1 to 3.0 µm and a height of 0.152 to 3.0 µm.