JPH1070166A - Semiconductor testing method and crystal defect sensing liquid used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the safety and workability in a crystall defect sensing processing. SOLUTION: To a thin film SOI substrate 1 comprising both a base substrate 1a made of Si and an oxide film 1b of a buried SiO2 film formed on this base substrate 1a, a crystal defect sensing liquid composed of nitric acid and hydrofluoric acid whose voluminal ratio to nitric acid is 1:(250-700) is used to process the substrate 1 by etching. Thereby, a dislocation 1e formed in an active layer 1c of the thin film SOI substrate 1 is sensed to inspect the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor manufacturing technique, and more particularly, to a semiconductor inspection method and a crystal defect detection solution for detecting and inspecting a crystal defect formed on a semiconductor substrate having an SOI (Silicon On Insulator) structure.

[0002]

2. Description of the Related Art The technology described below studies the present invention,
Upon completion, they were examined by the inventor, and the outline is as follows.

A semiconductor substrate having an SOI structure used for manufacturing a high-speed and low-power semiconductor integrated circuit device includes a Si (silicon) base substrate and an oxide film (SiO ₂ film) formed thereon. ) And an Si active layer formed thereon.

Here, a semiconductor substrate having an active layer having a thickness of 0.5 μm or less is called a thin film SOI substrate. As a typical example of the thin film SOI substrate, SIMOX is used.
(Separation by Implanted Oxygen) There is a substrate, and the active layer has a thickness of 0.1 to 0.3 μm.

In general, crystal defects such as threading dislocations are formed in the active layer of a SIMOX substrate. To detect such crystal defects, a crystal defect detection solution obtained by diluting a Secco solution with water to lower the etching rate is used. Is used.

The composition of the diluted Secco solution and a method for detecting a crystal defect using this crystal defect detection solution are described in, for example, “Vacuum Vol. 43, No. 4”, issued in 1992.
L. F. Giles et al., Pages 297-299.

[0007]

However, the main component of the Secco solution in the above technology is potassium dichromate (K ₂ Cr ₂ O ₇ ), which is hexavalent chromium (C
Since r ⁶⁺ ) is used, the following two problems can be raised when it is used.

(1). When a crystal defect detection liquid containing hexavalent chromium is used, the used crystal defect detection liquid must be collected and handed over to a waste liquid collection company, so that a recovery facility is required.

(2). The operation of collecting the used crystal defect detection liquid and delivering it to a waste liquid collection company and the cost associated therewith are required.

[0010] In addition, bulk Si containing no hexavalent chromium
In some cases, a mixed solution of acetic acid (CH ₃ COOH) -nitric acid (HNO ₃ ) -hydrofluoric acid (HF) (Japanese Industrial Standards-H0609, 1994) is used as a crystal defect detection liquid, When the thickness is large (approximately 0.6 μm / min), it is difficult to control the amount of Si removed, which is not suitable for detecting a crystal defect of a thin film SOI substrate.

An object of the present invention is to provide a semiconductor inspection method for improving safety and workability in a crystal defect detection process, and a crystal defect detection liquid used for the method.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0013]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the semiconductor inspection method of the present invention
Inspection of a semiconductor substrate having an OI structure, a step of preparing a crystal defect detection liquid formed by adding hydrofluoric acid to nitric acid, and a step of etching the semiconductor substrate using the crystal defect detection liquid. And inspecting by detecting a crystal defect formed in the semiconductor substrate by the etching process.

Thus, even if the crystal defect detecting liquid does not contain hexavalent chromium, the crystal defects formed on the semiconductor substrate can be preferentially etched.

As a result, it is possible to detect crystal defects in the semiconductor substrate without using hexavalent chromium.

In addition, since hexavalent chromium is not used, it is possible to eliminate the need to collect the crystal defect detection liquid and hand it over to a waste liquid collection company after using the crystal defect detection liquid. This eliminates the need to collect the crystal defect detection liquid.

As a result, a facility for recovering the crystal defect detection liquid is not required, and the cost can be reduced.

Further, in the semiconductor inspection method according to the present invention, the volume ratio of nitric acid and hydrofluoric acid constituting the crystal defect detection liquid is 250 to 250 parts per mole of hydrofluoric acid.
700.

Further, the semiconductor inspection method of the present invention can
A step of preparing a potassium hydroxide aqueous solution which is a crystal defect detection liquid formed by adding potassium hydroxide to water, wherein the semiconductor substrate is inspected using the crystal defect detection liquid. The method includes an etching process, wherein a crystal defect formed in the semiconductor substrate is detected and inspected by the etching process.

Note that the semiconductor inspection method of the present invention
A step of inspecting a semiconductor substrate having a structure, a step of preparing an aqueous solution of sodium hydroxide, which is a crystal defect detection solution formed by adding sodium hydroxide to water, and etching the semiconductor substrate using the crystal defect detection solution. The method includes a step of processing, wherein a crystal defect formed in the semiconductor substrate is detected and inspected by the etching process.

Further, the liquid for detecting a crystal defect of the present invention is an SOI
It is used in a semiconductor inspection method for inspecting a semiconductor substrate having a structure, and is composed of nitric acid and hydrofluoric acid, and has a volume ratio of nitric acid of 250 to 7 with respect to 1 of hydrofluoric acid.
00, which is used at the time of etching for detecting a crystal defect of the semiconductor substrate.

Further, the crystal defect detecting solution of the present invention is a liquid containing SO
A potassium hydroxide aqueous solution composed of water and potassium hydroxide and having a potassium hydroxide concentration of 1 to 20% by weight, which is used in a semiconductor inspection method for inspecting a semiconductor substrate having an I structure; It is used at the time of etching processing for detecting a crystal defect of a semiconductor substrate.

It should be noted that the crystal defect detecting solution of the present invention uses SOI
A sodium hydroxide aqueous solution which is used in a semiconductor inspection method for inspecting a semiconductor substrate having a structure and which is composed of water and sodium hydroxide and has a sodium hydroxide concentration of 1 to 20% by weight; This is used at the time of an etching process for detecting a crystal defect of a substrate.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIGS. 1 (a), 1 (b) and 1 (c)
FIG. 2 is an enlarged partial cross-sectional view showing an example of an embodiment of a structural change in a semiconductor substrate having an SOI structure when a crystal defect is detected by using the semiconductor inspection method of the present invention. FIG. And FIG. 3 is a conceptual diagram showing an example of an embodiment of the structure of an etching apparatus for detecting a crystal defect by using the crystal defect detection liquid of the present invention. FIG. 4 is an experimental result diagram showing an example of the embodiment of the relationship between the ratio and the etching rate. FIG. 4 is an example of the embodiment of the structure of the surface of the semiconductor substrate when a crystal defect is detected using the semiconductor inspection method of the present invention. FIG.

The semiconductor inspection method according to the first embodiment is formed, for example, on the active layer 1c of a thin-film SOI substrate 1 (semiconductor substrate) used when manufacturing a semiconductor integrated circuit device with high speed and low power consumption. Dislocation 1e (crystal defect)
Is detected by an etching process, and further inspected.

As shown in FIG. 1, the thin-film SOI substrate 1 is composed of a Si base substrate 1a and the base substrate 1a.
Oxide film 1b which is a buried SiO ₂ film formed thereon
And a silicon oxide active layer 1c formed on the oxide film 1b.

As an example, the thin film SOI substrate 1, which is the sample to be etched in the first embodiment, has a diameter of 150 mm, a thickness of the active layer 1c of 0.15 μm, and a thickness of the oxide film 1b of 0.1. It is 18 μm.

The structure of the etching apparatus 3 (see FIG. 2) when detecting the dislocation 1e using the semiconductor inspection method according to the first embodiment will be described with reference to FIGS.

The etching apparatus 3 includes a plurality of thin films SO
It has a substrate storage case 3a that can store the I substrate 1 and an etching container 3b that can store the substrate storage case 3a and the crystal defect detection liquid 2.

Here, the substrate accommodating case 3a and the etching container 3b are made of, for example, a hydrofluoric acid-resistant material such as polypropylene.

The crystal defect detection liquid 2 according to the first embodiment is used for the semiconductor inspection method, and is composed of nitric acid and hydrofluoric acid and has a volume ratio of hydrofluoric acid 1 Nitric acid 250 to 700,
This is an etchant used in an etching process for detecting dislocations 1e in the active layer 1c.

The etching rate of the crystal defect detection liquid 2 at room temperature during the etching treatment is 10 to 3
It is preferable to set the range to 0 nm / min.

This is to set the etching rate of the crystal defect detection liquid 2 at room temperature in a range where the amount of Si removed can be easily controlled. If the etching rate is less than 10 nm / min, the efficiency at the time of the etching process is reduced. Bad, 30nm
If the speed exceeds / min, unevenness may be formed in the portion to be etched of the thin-film SOI substrate 1, so that the thickness is set to 10 to 30 nm / min.

Further, from the experimental results of the etching rate shown in FIG. 3, in order to make the etching rate of the crystal defect detection liquid 2 fall within the range of 10 to 30 nm / min, hydrogen fluoride in the crystal defect detection liquid 2 is used. When the composition ratio (volume ratio) of acid and nitric acid is hydrofluoric acid: nitric acid = 1: 250-70
It can be derived that it is zero.

Thus, in the first embodiment,
As an example, a case where the volume ratio between the hydrofluoric acid and the nitric acid is 1: 400 will be described.

The semiconductor inspection method according to the first embodiment will be described.

In the semiconductor inspection method, the dislocation 1e formed in the active layer 1c is detected and inspected.
A crystal defect detection liquid 2 formed by adding hydrofluoric acid to nitric acid (or nitric acid may be added to hydrofluoric acid) is prepared.

That is, a predetermined amount of nitric acid (for example, a concentration of 65%) is put into the etching container 3b, and a predetermined amount of hydrofluoric acid (for example, a concentration of 49%) is added thereto and mixed.
A crystal defect detection liquid 2 is prepared.

At this time, the crystal defect detection liquid 2 is prepared so that the volume ratio of the hydrofluoric acid and the nitric acid constituting the crystal defect detection liquid 2 is 250 to 700 nitric acid with respect to 1 hydrofluoric acid. In the first embodiment, the volume ratio between the hydrofluoric acid and the nitric acid is 1: 400.

At this time, the etching rate of the crystal defect detection liquid 2 with respect to Si is about 20 nm / min at room temperature.

The temperature of the crystal defect detection liquid 2 at the time of performing the etching treatment is kept at room temperature (23 ± 3 ° C.).

Subsequently, using the crystal defect detection liquid 2, FIG.
A first etching process is performed on the thin film SOI substrate 1 shown in (a) (the etching process using the crystal defect detection liquid 2 according to the first embodiment is only the first etching process). Here, dislocations 1e are formed in the active layer 1c of the thin film SOI substrate 1 shown in FIG.

As shown in FIG. 2, the etching process is performed by accommodating a plurality of thin film SOI substrates 1 in a substrate accommodating case 3a and immersing the substrate accommodating cases 3a together in the crystal defect detection liquid 2 for about 4 minutes.

Further, after the completion of the etching process, the substrate is washed with water for about 10 minutes.

As a result, the active layer 1c of the thin film SOI substrate 1 after the first etching process is
Fine pores 1d are formed as shown in FIG.

Since the etching rate of the crystal region along the dislocation 1e of the active layer 1c shown in FIG. 1A is larger than that of the perfect crystal region, the pores reaching the oxide film 1b from the surface along the dislocation 1e. 1d is formed.

However, since the opening 1f on the surface shown in FIG. 1B is very small, it is difficult to observe the opening 1f with a metallographic microscope or the like.

Therefore, the second etching process is performed on the thin film SOI substrate 1 shown in FIG.

First, a predetermined amount of hydrofluoric acid (concentration 49
%) And a predetermined amount of deionized water is added to prepare an oxide etching solution for etching the oxide film 1b.

At this time, the mixing ratio (volume ratio) of hydrofluoric acid and deionized water is 1: 1.

The second etching process (the oxide film 1
The temperature of the oxide film etching solution at the time of performing the etching process (b) is also kept at room temperature (23 ± 3 ° C.).

The thin film SOI substrate 1 having been washed with water is immersed in the oxide film etching solution for about 6 minutes to perform an etching process on the oxide film 1b.

As a result, the oxide film etching solution is
d, penetrates into the oxide film 1b, dissolves the oxide film 1b, and forms a void 1g shown in FIG. 1 (c).

Thereafter, the thin film SOI substrate 1 is taken out of the oxide film etching solution, washed with water for about 10 minutes, and dried with a spinner or the like.

Thus, dislocations 1e formed in active layer 1c can be detected and inspected by the first and second etching processes.

That is, using a metallographic microscope or the like, dislocation 1
e can be observed (inspected) as a void 1g in the oxide film 1b instead.

Here, the enlarged partial plan view shown in FIG. 4 is obtained by photographing the surface of the thin film SOI substrate 1 with a metallographic microscope, whereby the void 1g in the oxide film 1b can be observed.

Further, the density of the dislocation 1e can be obtained by measuring the density of the void 1g in the oxide film 1b.

According to the semiconductor inspection method of the first embodiment and the crystal defect detection liquid used therein, the following operation and effect can be obtained.

That is, the active layer 1c of the thin film SOI substrate 1
When the dislocation 1e in the inside is detected by the etching process,
By etching using a crystal defect detection solution 2 formed by adding hydrofluoric acid to nitric acid, even if the crystal defect detection solution 2 does not contain hexavalent chromium, the active layer 1
Dislocations 1e formed in c can be preferentially etched.

Thus, the crystal defect detection liquid 2 is composed of nitric acid and hydrofluoric acid, and the composition ratio (volume ratio) thereof is preferably hydrofluoric acid: nitric acid = 1: 250-700. As shown in FIG. 4, since the dislocation 1e can be detected, it can be inspected (observed).

That is, the thin film SO is used without using hexavalent chromium.
The work of detecting the dislocation 1e in the active layer 1c of the I-substrate 1 can be performed.

In addition, since hexavalent chromium is not used, the operation of recovering the crystal defect detection liquid 2 and transferring it to a waste liquid recovery company after using the crystal defect detection liquid 2 can be eliminated.

As a result, a facility for collecting the crystal defect detection liquid 2 is not required, thereby reducing costs.

In addition, since it is not necessary to deliver the used crystal defect detection liquid 2 to the waste liquid recovery trader, the work of delivering the crystal defect detection liquid and the cost associated therewith can be eliminated.
Therefore, the waste liquid treatment in the crystal defect detection liquid 2 can be simplified, and the workability of the crystal defect detection can be improved and the cost for the crystal defect detection processing can be reduced.

Since the crystal defect detecting liquid 2 containing no hexavalent chromium is used, the safety of the worker is also ensured.

Further, by setting the etching rate in the etching process for detecting the dislocation 1e in the range of 10 to 30 nm / min, the control of the amount of Si removed from the active layer 1c becomes relatively easy, and the thin film SOI substrate 1 active layer 1
It is possible to accurately detect the dislocation 1e at c.

(Embodiment 2) FIG. 5 shows the relationship between the concentration in a crystal defect detection solution and the etching rate when an etching process is performed using a crystal defect detection solution according to another embodiment of the present invention. FIG. 6 is an enlarged partial plan view showing the structure of the surface of a semiconductor substrate when a crystal defect is detected by using a semiconductor inspection method according to another embodiment of the present invention.

The semiconductor inspection method according to the second embodiment, like the semiconductor inspection method according to the first embodiment, uses a thin-film SOI used for manufacturing the high-speed and low-power semiconductor integrated circuit device shown in FIG. Dislocations 1e (crystal defects) formed in the active layer 1c of the substrate 1 (semiconductor substrate) are detected by an etching process and further inspected.

The thin film SOI which is the sample to be etched is
The substrate 1 is a SIMOX substrate, the structure of which is the same as that described in the first embodiment, and a duplicate description thereof will be omitted.

The etching apparatus 3 (FIG. 2) for detecting the dislocation 1e using the semiconductor inspection method of the second embodiment
2) is the same as that described in the first embodiment, but the substrate housing case 3a and the etching container 3b are formed of an alkali-resistant material. Other structures are described in Embodiment 1.
Are the same as those described above, and the description thereof will not be repeated.

Here, the crystal defect detection liquid 2 according to the second embodiment is used for the semiconductor inspection method.
A potassium hydroxide aqueous solution composed of water and potassium hydroxide and having a concentration of the potassium hydroxide of 1 to 20% by weight, and detects the dislocation 1e of the active layer 1c of the thin film SOI substrate 1 shown in FIG. It is an etchant used at the time of the etching process.

The etching rate of the crystal defect detection liquid 2 at the time of performing the etching treatment is 10 to 30 nm / min for the same reason as described in the first embodiment (for details, see the first embodiment). It is preferable to set the range.

Further, from the experimental results of the etching rate shown in FIG. 5, in order to make the etching rate of the crystal defect detection liquid 2 fall within the range of 10 to 30 nm / min, potassium hydroxide in the crystal defect detection liquid 2 was used. Concentration of 1 to 20
Weight%.

When the concentration of potassium hydroxide is less than 1% by weight, the etching rate becomes unstable, and when the concentration is 10 to 12% by weight, the etching rate becomes maximum. It is set to 1 to 20% by weight (the range of the upper limit value is widened in consideration of the variation and error of the experimental value).

Thus, in the second embodiment,
As an example, the concentration of the potassium hydroxide is 5% by weight.
The case will be described.

The semiconductor inspection method according to the second embodiment will be described with reference to FIGS. 1, 2, 5 and 6.

First, the natural oxide film formed on the surface of the thin film SOI substrate 1 is removed by etching.

The etching solution used at this time is a mixed solution of hydrofluoric acid (concentration 49%) and water, and the ratio (volume ratio) of hydrofluoric acid: water = 1: 10.

Thus, using the etching solution, 1
Pre-treatment is performed for about a minute to remove the natural oxide film. Further, after the etching process, the substrate is sufficiently washed with water.

Thereafter, a crystal defect detection liquid 2 formed by adding potassium hydroxide to water (or water may be added to potassium hydroxide) is prepared.

That is, a predetermined amount of water is put into the alkali-resistant etching container 3b, and a predetermined amount of potassium hydroxide is added thereto and mixed (mixed) to form an aqueous potassium hydroxide solution as the crystal defect detection liquid 2. .

At this time, the concentration of potassium hydroxide in the aqueous solution of potassium hydroxide as the crystal defect detection liquid 2 was 1 to 2
Formulate to be 0% by weight. In addition, Embodiment 2
In this case, the concentration of the potassium hydroxide is 5% by weight.

At this time, (10)
0) The etching rate for the plane is about 25 at room temperature.
nm / min.

The temperature of the crystal defect detection liquid 2 at the time of performing the etching treatment is kept at room temperature (23 ± 3 ° C.).

Subsequently, using the crystal defect detection liquid 2, FIG.
(A) The first etching process is performed on the thin film SOI substrate 1 (the etching process using the crystal defect detection liquid 2 of the second embodiment is the same as in the first embodiment).
Only the second etching process). Here, FIG.
In the thin film SOI substrate 1 shown in (a), dislocations 1e are formed in the active layer 1c.

As shown in FIG. 2, the etching process is performed by accommodating a plurality of thin-film SOI substrates 1 in a substrate accommodating case 3a and immersing the entire substrate accommodating case 3a in the crystal defect detection liquid 2 for about 3 minutes.

Further, after the completion of the etching process, the substrate is washed with water for about 10 minutes.

Subsequently, a second etching process is performed as in the first embodiment.

Since the second etching process is the same as that described in the first embodiment,
The overlapping description is omitted.

As a result, the active layer 1 of the thin film SOI substrate 1
Dislocations 1e formed in c can be detected and inspected by the first and second etching processes.

That is, using a metallographic microscope or the like, dislocation 1
e can be observed (inspected) as a void 1g instead.

Here, the enlarged partial plan view shown in FIG. 6 is an image of the surface of the thin film SOI substrate 1 taken with a metallographic microscope, whereby the void 1g can be observed.

Further, the density of the dislocations 1e can be obtained by measuring the density of the voids 1g in the oxide film 1b.

According to the semiconductor inspection method of the second embodiment and the crystal defect detection liquid used therein, the following operation and effect can be obtained.

That is, the active layer 1c of the thin film SOI substrate 1
When detecting dislocations 1e by etching, a crystal defect detection solution 2 formed by adding potassium hydroxide to water
The dislocation 1e can be preferentially etched even in the crystal defect detection liquid 2 that does not contain hexavalent chromium by performing the etching treatment using.

Thus, the crystal defect detection liquid 2 is an aqueous potassium hydroxide solution comprising water and potassium hydroxide, and the concentration of potassium hydroxide is preferably 1 to 20% by weight.
As a result, as shown in FIG. 6, the dislocation 1e can be detected, so that it is possible to inspect (observe) it.

That is, the thin film SO is used without using hexavalent chromium.
The work of detecting the dislocation 1e of the active layer 1c of the I-substrate 1 can be performed.

The other functions and effects obtained by the semiconductor inspection method according to the second embodiment and the crystal defect detection liquid used therefor are the same as those described in the first embodiment, and thus redundant description will be omitted. I do.

(Embodiment 3) FIG. 7 shows the relationship between the concentration in a crystal defect detection solution and the etching rate when etching is performed using a crystal defect detection solution according to another embodiment of the present invention. FIG. 8 is an enlarged partial plan view showing the structure of the surface of the semiconductor substrate when a crystal defect is detected by using the semiconductor inspection method according to another embodiment of the present invention.

The semiconductor inspection method according to the third embodiment, like the semiconductor inspection method according to the first embodiment, uses a thin film SOI used for manufacturing the high-speed and low-power semiconductor integrated circuit device shown in FIG. Dislocations 1e (crystal defects) formed in the active layer 1c of the substrate 1 (semiconductor substrate) are detected by an etching process and further inspected.

The thin film SOI which is the sample to be etched is
The substrate 1 is a SIMOX substrate, the structure of which is the same as that described in the first embodiment, and a duplicate description thereof will be omitted.

The etching apparatus 3 (FIG. 2) for detecting the dislocation 1e using the semiconductor inspection method of the third embodiment.
Also, the structure is the same as that described in the second embodiment, and the description thereof will not be repeated.

Here, the crystal defect detection liquid 2 according to the third embodiment is used for the semiconductor inspection method.
An aqueous sodium hydroxide solution composed of water and sodium hydroxide and having a concentration of the sodium hydroxide of 1 to 20% by weight, and detects the dislocation 1e of the active layer 1c of the thin film SOI substrate 1 shown in FIG. It is an etchant used at the time of the etching process.

The etching rate of the crystal defect detection liquid 2 at the time of performing the etching treatment is 10 to 30 nm / min for the same reason as described in the first embodiment (for details, refer to the first embodiment). It is preferable to set the range.

Further, from the experimental results of the etching rate shown in FIG. 7, in order to make the etching rate of the crystal defect detection liquid 2 fall within the range of 10 to 30 nm / min, sodium hydroxide in the crystal defect detection liquid 2 was used. Concentration of 1-2
0% by weight can be derived.

The reason for this is that when the concentration of sodium hydroxide is less than 1% by weight, the etching rate becomes unstable, and when the concentration is about 15% by weight, the etching rate becomes maximum. To 20% by weight (the range of the upper limit value was widened in consideration of the variation and error of the experimental value).

As a result, in the third embodiment,
As an example, a case where the concentration of the sodium hydroxide is 10% by weight will be described.

A semiconductor inspection method according to the third embodiment will be described with reference to FIGS. 1, 2, 7 and 8.

First, the natural oxide film formed on the surface of the thin film SOI substrate 1 is removed by etching.

The etching solution used at this time is the same hydrofluoric acid (concentration 49) as that described in the second embodiment.
%) And water, and the ratio (volume ratio) of hydrofluoric acid: water = 1: 10.

[0114] Thus, 1
Pre-treatment is performed for about a minute to remove the natural oxide film. Further, after the etching process, the substrate is sufficiently washed with water.

Thereafter, a crystal defect detection liquid 2 formed by adding sodium hydroxide to water (water may be added to sodium hydroxide) is prepared.

That is, a predetermined amount of water is put into the alkali-resistant etching vessel 3b, and a predetermined amount of sodium hydroxide is added thereto and mixed (mixed) to form an aqueous solution of sodium hydroxide as the crystal defect detection liquid 2. .

At this time, in the aqueous solution of sodium hydroxide as the crystal defect detection liquid 2, the concentration of sodium hydroxide was 1
Formulated to be 〜20% by weight. In the third embodiment, the concentration of the sodium hydroxide is 10
% By weight.

At this time, (10)
0) The etching rate for the plane is about 20 at room temperature.
nm / min.

The temperature of the crystal defect detection liquid 2 during the etching process is kept at room temperature (23 ± 3 ° C.).

Subsequently, using the crystal defect detection liquid 2, FIG.
(A) The first etching process is performed on the thin film SOI substrate 1 (the etching process using the crystal defect detection liquid 2 of the third embodiment is the same as that of the first embodiment).
Only the second etching process). Here, FIG.
In the thin film SOI substrate 1 shown in (a), dislocations 1e are formed in the active layer 1c.

As shown in FIG. 2, the etching process is performed by accommodating a plurality of thin-film SOI substrates 1 in a substrate accommodating case 3a and immersing the entire substrate accommodating case 3a in the crystal defect detection liquid 2 for about 3 minutes.

Further, after the completion of the etching process, the substrate is washed with water for about 10 minutes.

Subsequently, a second etching process is performed in the same manner as in the first embodiment.

The second etching process is the same as that described in the first embodiment.
The overlapping description is omitted.

Thus, the active layer 1 of the thin-film SOI substrate 1
Dislocations 1e formed in c can be detected and inspected by the first and second etching processes.

In other words, the dislocation 1
e can be observed (inspected) as a void 1g instead.

Here, the enlarged partial plan view shown in FIG. 8 is a photograph of the surface of the thin film SOI substrate 1 taken with a metallurgical microscope, whereby the gap 1g can be observed.

Further, by measuring the density of the void 1g in the oxide film 1b, the density of the dislocation 1e can be obtained.

According to the semiconductor inspection method of the third embodiment and the crystal defect detection liquid used therein, the following operation and effect can be obtained.

That is, the active layer 1c of the thin film SOI substrate 1
When the dislocation 1e in the inside is detected by the etching process,
By etching using the crystal defect detection liquid 2 formed by adding sodium hydroxide to water, even if the crystal defect detection liquid 2 does not contain hexavalent chromium, dislocation 1
e can be preferentially etched.

Thus, the crystal defect detection liquid 2 is an aqueous sodium hydroxide solution comprising water and sodium hydroxide, and the concentration of sodium hydroxide is preferably 1 to 20.
%, Dislocation 1e as shown in FIG.
Can be detected, which can be inspected (observed).

That is, without using hexavalent chromium, the thin film SO
The work of detecting the dislocation 1e in the active layer 1c of the I-substrate 1 can be performed.

The other effects obtained by the semiconductor inspection method according to the third embodiment and the crystal defect detection liquid used therefor are the same as those described in the first embodiment, and therefore, redundant description will be omitted. I do.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the embodiments of the present invention, and does not depart from the gist of the invention. It is needless to say that various changes can be made.

For example, in Embodiments 1, 2 and 3, the thin film SOI substrate 1
When etching the thin film SOI substrate 1
(See FIG. 2). However, in the etching process, the thin film SOI substrate 1 may be etched one by one, that is, one by one.

In this case, the thin film SOI substrate 1 which is a sample to be etched is gripped by tweezers or the like, and the thin film SOI substrate 1 is immersed in a predetermined crystal defect detection liquid 2.

[0137]

Advantageous effects obtained by typical ones of the inventions disclosed by the present application will be briefly described as follows.
It is as follows.

(1). When a crystal defect of a semiconductor substrate having an SOI structure is detected by an etching process, a crystal defect detection liquid formed by adding hydrofluoric acid to nitric acid, or
By etching using a crystal defect detection solution such as an aqueous solution of potassium hydroxide or sodium hydroxide, even a crystal defect detection solution that does not contain hexavalent chromium can preferentially etch crystal defects. it can.
As a result, the work of detecting crystal defects in the semiconductor substrate can be performed without using hexavalent chromium.

(2). Since hexavalent chromium is not used, after using the crystal defect detection liquid, the operation of collecting the crystal defect detection liquid and transferring it to a waste liquid collection company can be omitted. Therefore, it is not necessary to collect the crystal defect detection liquid.
As a result, there is no need for a facility for collecting a crystal defect detection liquid, thereby reducing costs.

(3). Since there is no need to hand over the used crystal defect detection solution to a waste liquid recovery company, this work and associated costs can be eliminated, and the workability of crystal defect detection and the cost of crystal defect detection processing can be reduced. Reduction can be achieved.

(4). According to the above (1), (2) and (3),
It is possible to simplify the waste liquid treatment in the crystal defect detection liquid and improve the workability of the crystal defect detection.

(5). Since a crystal defect detection liquid containing no hexavalent chromium is used, the safety of workers engaged in the preparation and the crystal defect detection processing is ensured.

(6). By setting the etching rate in the etching process for detecting a crystal defect in the range of 10 to 30 nm / min, it is relatively easy to control the amount of Si removed from the active layer even when the thin film SOI substrate is etched. That is, it is possible to accurately detect a crystal defect in the thin film SOI substrate.

[Brief description of the drawings]

FIGS. 1A, 1B, and 1C are enlarged views showing an example of an embodiment of a structural change in a semiconductor substrate having an SOI structure when detecting a crystal defect using the semiconductor inspection method of the present invention. It is a partial sectional view.

FIG. 2 is a conceptual configuration diagram showing an example of an embodiment of the structure of an etching apparatus when detecting a crystal defect using the semiconductor inspection method of the present invention.

FIG. 3 is an experimental result diagram showing an example of a relationship between a composition ratio of a crystal defect detection solution and an etching rate when an etching process is performed using the crystal defect detection solution of the present invention.

FIG. 4 is an enlarged partial plan view showing an example of an embodiment of a structure of a surface of a semiconductor substrate when a crystal defect is detected using the semiconductor inspection method of the present invention.

FIG. 5 is an experimental result diagram showing a relationship between a concentration in a crystal defect detection solution and an etching rate when an etching process is performed using a crystal defect detection solution according to another embodiment of the present invention.

FIG. 6 is an enlarged partial plan view showing a structure of a surface of a semiconductor substrate when a crystal defect is detected by using a semiconductor inspection method according to another embodiment of the present invention.

FIG. 7 is an experimental result diagram showing a relationship between a concentration in a crystal defect detection solution and an etching rate when an etching process is performed using a crystal defect detection solution according to another embodiment of the present invention.

FIG. 8 is an enlarged partial plan view showing a structure of a surface of a semiconductor substrate when a crystal defect is detected by using a semiconductor inspection method according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 thin film SOI substrate (semiconductor substrate) 1a base substrate 1b oxide film 1c active layer 1d pore 1e dislocation (crystal defect) 1f opening 1g void 2 crystal defect detection liquid 3 etching apparatus 3a substrate housing case 3b etching container

Claims (9)

[Claims] 1. A semiconductor inspection method for inspecting a semiconductor substrate having an SOI structure, comprising: preparing a crystal defect detection liquid formed by adding hydrofluoric acid to nitric acid; A semiconductor inspection method, comprising a step of etching a semiconductor substrate, wherein a crystal defect formed in the semiconductor substrate is detected and inspected by the etching processing. 2. The semiconductor inspection method according to claim 1, wherein the volume ratio of nitric acid and hydrofluoric acid constituting the crystal defect detection liquid is from 250 to 250 nitric acid to 1 hydrofluoric acid. 700. A semiconductor inspection method, comprising: 3. A semiconductor inspection method for inspecting a semiconductor substrate having an SOI structure, wherein a step of preparing a potassium hydroxide aqueous solution which is a crystal defect detection liquid formed by adding potassium hydroxide to water; A semiconductor inspection method comprising: a step of etching the semiconductor substrate using a liquid; and detecting and inspecting a crystal defect formed in the semiconductor substrate by the etching process. 4. The semiconductor inspection method according to claim 3, wherein the concentration of potassium hydroxide in the aqueous potassium hydroxide solution is 1 to 20% by weight. 5. A semiconductor inspection method for inspecting a semiconductor substrate having an SOI structure, wherein a step of preparing an aqueous solution of sodium hydroxide which is a crystal defect detection liquid formed by adding sodium hydroxide to water; A semiconductor inspection method comprising: a step of etching the semiconductor substrate using a liquid; and detecting and inspecting a crystal defect formed in the semiconductor substrate by the etching process. 6. The semiconductor inspection method according to claim 5, wherein the concentration of sodium hydroxide in the aqueous sodium hydroxide solution is 1 to 20% by weight. 7. A crystal defect detection liquid used in a semiconductor inspection method for inspecting a semiconductor substrate having an SOI structure, wherein the liquid is composed of nitric acid and hydrofluoric acid, and has a volume ratio of 1 to hydrofluoric acid. A crystal defect detection liquid, which is 250 to 700 nitric acid and is used at the time of an etching process for detecting a crystal defect of the semiconductor substrate. 8. A crystal defect detection liquid for use in a semiconductor inspection method for inspecting a semiconductor substrate having an SOI structure, wherein the liquid is composed of water and potassium hydroxide and has a potassium hydroxide concentration of 1 to 20% by weight. A crystal defect detection liquid, which is used during an etching process for detecting a crystal defect of the semiconductor substrate. 9. A crystal defect detection liquid for use in a semiconductor inspection method for inspecting a semiconductor substrate having an SOI structure, wherein the liquid is composed of water and sodium hydroxide and has a sodium hydroxide concentration of 1 to 20% by weight. A sodium hydroxide aqueous solution as described above, which is used during an etching process for detecting a crystal defect of the semiconductor substrate.