JP2003194732A - Evaluation method for soi wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the evaluation method that can conveniently and accurately evaluate the inspection of a microdefect caused by Cu contamination against an SOI wafer, especially a semiconductor layer. <P>SOLUTION: In the evaluation method for the SOI wafer where the semiconductor layer, an insulation layer, and a supporting substrate are formed in sequence, a defect in the semiconductor layer is actualized and evaluated with the laser microscope of a confocal optical system. Specially, when the semiconductor layer is silicon, the defect is evaluated with the microscope of the confocal optical system after etching process with the process liquid of ammonia water and hydrogen peroxide water to remove a part of the semiconductor layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SOI (Semicon) in which a semiconductor layer, an insulating layer, and a supporting substrate are sequentially formed.
If the inductor On Insulator or the semiconductor layer is silicon, Silicon On Insul
Abbreviation of ator) relates to a wafer evaluation method. Especially SO
The present invention relates to a method for evaluating an SOI wafer which reveals the presence of metal contamination on the I wafer.

[0002]

2. Description of the Related Art In recent years, the degree of integration of an integrated circuit has remarkably increased, and as a result, processing conditions such as flatness and smoothness of a mirror-polished semiconductor single crystal wafer surface have become more severe. It was Moreover, in order to obtain an integrated circuit with high performance, reliability, and yield, not only mechanical precision but also electrical characteristics are required to be high. Above all, regarding SOI wafers,
Since it is an ideal dielectric isolation substrate, it is mainly used as a high-frequency and high-speed device for mobile communication equipment and medical equipment.
It is expected that demand will increase significantly in the future.

An SOI wafer has a structure in which a semiconductor layer (also referred to as an SOI layer or an active layer), an insulating layer (also referred to as a BOX oxide film or simply an oxide film), and a support substrate (also referred to as a substrate layer) are sequentially formed. ing.

In particular, there is an SOI wafer in which the semiconductor layer is silicon and the insulating layer is a silicon oxide film. As a method of manufacturing a wafer having such an SOI structure, SIMOX (se is formed by implanting oxygen ions into a silicon single crystal at a high concentration and then performing a heat treatment at a high temperature to form an oxide film (insulating layer).
partition by implemented oxy
gen) method and two mirror-polished silicon wafers are bonded without using an adhesive, and one wafer is thinned.

In the SIMOX method, since the film thickness of the active layer portion (semiconductor layer) which becomes the device active region can be determined and controlled by the acceleration voltage at the time of implanting oxygen ions, the active layer is thin and highly uniform in film thickness. Although there is an advantage that the layer can be easily obtained, there are many problems such as reliability of the buried oxide film (insulating layer), crystallinity of the active layer, and heat treatment at a temperature of 1300 ° C. or higher.

On the other hand, in the wafer bonding method, an oxide film (insulating layer) is formed on at least one of two single crystal silicon mirror-polished wafers, the wafers are bonded together without using an adhesive, and then a heat treatment (usually 1100 ° C. (1200 ° C.) to strengthen the bond, and then one wafer is thinned by grinding or wet etching, and then the surface of the thin film is mirror-polished to form an SOI layer (semiconductor layer). There is an advantage that the oxide film (insulating layer) has high reliability and the crystallinity of the SOI layer is good, but the film thickness of the SOI layer obtained by mechanical processing and its uniformity are limited. There is.

Recently, as a method of manufacturing an SOI wafer,
A method for producing an SOI wafer by combining and separating ion-implanted wafers has begun to receive new attention. In this method, an oxide film (insulating layer) is formed on at least one of two silicon wafers, and hydrogen ions or rare gas ions are injected from the upper surface of the one silicon wafer to form a microbubble layer inside the wafer. After forming the (encapsulation layer), the ion-implanted surface is adhered to the other silicon wafer through the oxide film, and then heat treatment is applied to make one wafer into a thin film with the microbubble layer as the cleavage surface. And then heat-treated to firmly bond them to SOI
Wafer technology (see Japanese Patent Application Laid-Open No. 5-211128)
Is. The cleaved surface is a good mirror surface, and the SOI
An SOI wafer in which the film thickness of the layers (semiconductor layers) is also highly uniform can be obtained relatively easily. In addition to this, various manufacturing methods have been developed.

As a characteristic of such an SOI wafer, the oxide film breakdown voltage characteristic is important. For example, TZDB / of MOS gate oxide film, which is an important electrical characteristic of the device,
TDDB characteristics are important. This property is an important indicator of yield and long-term reliability. The TZDB / TDDB characteristics are obtained by applying an electric field stepwise to a MOS capacitor and measuring the dielectric breakdown field strength of the MOS capacitor (electric field breakdown distribution: TZDB method; Time Zero D).
(electric breakdown) and a method of measuring the rate at which the MOS capacitor is destroyed over time by changing the magnitude of the electric field by applying a constant electric field (time-dependent breakdown distribution: TDDB method; Time Dependent).
ent Dielectric Breakdown)
It was evaluated by.

As an evaluation other than the oxide film withstand voltage characteristic,
There is a method of inspecting a defect using a general light-scattering type particle counter or the like for a specular wafer or the like. However, with such a light scattering type measuring device, the SOI
When the wafer is evaluated, scattering noise occurs due to the film interface of the insulating layer interposed between the semiconductor layer and the supporting substrate, and the evaluation becomes very difficult.

There are other evaluation methods using an apparatus such as a scanning electron microscope (SEM) and a transmission electron microscope (TEM), but the inspection is difficult because the defects of the SOI wafer are very small. It was

Therefore, in order to evaluate the defects of the SOI wafer, the SOI wafer is subjected to seco etching (a method of etching using an etching solution containing hydrofluoric acid and potassium dichromate) to generate etch pits due to micro defects. Furthermore, a method has been proposed in which the etch pit is enlarged to a measurable size, and then the surface SOI layer is removed to evaluate defects (J. Electroch).
em. soc. , Vol. 140, No. 6, June
1993, 1713-1716). This method is mainly for evaluating dislocation defects. In this method, there are problems regarding the influence of metals such as chromium contained in the etching solution and the disposal of the etching solution.

Therefore, in order to inspect the minute defects existing in the SOI wafer, the SOI wafer is cleaned with an alkaline cleaning solution as described in, for example, Japanese Patent Laid-Open No. 11-74493, and the SOI layer on the surface is removed. After the film thickness of 1 μm, the SOI wafer is dipped in a hydrofluoric acid solution to generate minute etch pits due to defects existing in the SOI layer, and the minute etch pits are directly dipped in the hydrofluoric acid solution for etching. After enlarging the pit size, the defect density is measured by a defect evaluation device using laser light, SEM, TE.
A method has been developed in which measurement is performed using M, an atomic force microscope (AFM), or the like. This is mainly COP (Crys
This is to evaluate a defect called “tal Originated Particle”.

[0013]

When the process of forming an oxide film and the process of etching the oxide film are repeated several times in the process of forming a device, the gate insulating film breakdown characteristic is deteriorated, resulting in performance and reliability. -There was a problem that devices with high yield could not be formed. Especially SOI
In the wafer, the heavy metal impurities mixed in the semiconductor layer cannot pass through the insulating film and accumulate in the semiconductor layer without gettering to the supporting substrate side. There is a problem that the characteristics are deteriorated.

Therefore, the quality requirements for the SOI wafer have become stricter, and it has become necessary to confirm the minute defects of the SOI wafer, especially the defects caused by metal contamination, for example, the contamination state of the semiconductor layer with Cu or the like.

On the other hand, as a method for evaluating minute defects in a normal mirror-polished wafer or the like, Japanese Patent Laid-Open No. 03-233955 is available.
It is known that the wafer can be evaluated by repeatedly etching the wafer with a solution of ammonia water-hydrogen peroxide water-water and detecting defects with a particle counter, as disclosed in Japanese Patent Laid-Open Publication No. H11-242242. In addition, particularly for the evaluation of minute defects due to contamination by Cu or the like, it is possible to improve by using a treatment liquid having a specific composition consisting of ammonia water and hydrogen peroxide water as disclosed in JP-A-2000-208578. The sensitivity can be evaluated.

Therefore, it is conceivable to evaluate Cu contamination and the like by using such a method also for the SOI wafer, but it is treated with a treatment liquid consisting of ammonia water-hydrogen peroxide water-water, and the light scattering method is used. When a defect is detected by the particle counter of No. 3, as described above, in the SOI wafer, the normal laser light used in the particle counter or the like causes scattering noise due to the film interface of the insulating layer interposed between the semiconductor layer and the supporting substrate, Evaluation becomes very difficult.

On the other hand, as described in JP-A No. 11-74493, cleaning with an alkaline cleaning solution,
Further, when the oxide film corresponding to minute defects in the semiconductor layer is partially etched by secondary immersion in hydrofluoric acid to form secondary etch pits, the etch pits themselves can be made larger, and thus the conventional optical pits can be formed. A scattering-type particle counter can detect signals above the influence of noise and can be evaluated. However, this method requires treatment with hydrofluoric acid, and depending on the size of the defects in the semiconductor layer, if the oxide film in the portion corresponding to the microdefects is not etched, or conversely, the etch pit itself becomes too large, and In some cases, it cannot be separated from defects and the like, and it is a problem whether these secondary etch pits really reflect defects in the semiconductor layer. In addition, when evaluated by SEM, TEM, AFM, or the like after processing by this method, it is difficult to evaluate the entire surface of the SOI wafer because the evaluation area is very small.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an evaluation method capable of easily and accurately evaluating an inspection of a minute defect caused by Cu contamination or the like on an SOI wafer, particularly a semiconductor layer. To aim.

[0019]

A method for evaluating an SOI wafer according to the present invention is a method for evaluating an SOI wafer in which a semiconductor layer, an insulating layer and a supporting substrate are sequentially formed, and defects existing in the semiconductor layer are revealed. It is characterized in that it is evaluated by a laser microscope with a confocal optical system.

As described above, after the semiconductor layer of the SOI wafer is first pretreated to reveal the defects, the quality of the SOI wafer is evaluated by evaluating the revealed defects using a laser microscope of a conformal optical system. Can be evaluated accurately and easily.

Particularly, the method for evaluating an SOI wafer according to the present invention is an SO in which a semiconductor layer, an insulating layer and a supporting substrate are sequentially formed.
A method for evaluating an I wafer, in which an SOI wafer is etched with a treatment liquid consisting of ammonia water and hydrogen peroxide water to remove a part of the semiconductor layer, and then evaluated with a laser microscope of a confocal optical system. Characterize. In particular, SO in which the semiconductor layer is silicon and the insulating layer is a silicon oxide film
It is useful for evaluation of I wafers.

As described above, a part of the semiconductor layer (silicon layer) of the SOI wafer is etched with a treatment liquid consisting of ammonia water and hydrogen peroxide water to remove minute defects, especially defects which are considered to be caused by contamination by Cu or the like. Noise can be suppressed by making it visible and then evaluated by a laser microscope with a confocal optical system, and minute defects, particularly extremely minute defects due to metal contamination by Cu or the like, can be accurately evaluated.

In the case of the evaluation method of the present invention, how to treat the semiconductor layer (silicon layer) of an SOI wafer, in particular, to reveal minute defects, particularly extremely minute defects which are considered to be caused by contamination by Cu or the like, Another problem is how to accurately detect defects by reducing the influence of the insulating film and the like.

In the present invention, as an example of the treatment for revealing a minute defect, it can be carried out by etching the semiconductor layer using an etching solution having selectivity for the defect to be detected.

For example, in the case of an SOI wafer in which the semiconductor layer is silicon and the insulating layer is a silicon oxide film, a part of the semiconductor layer (silicon layer) is ammonia water-hydrogen peroxide solution-
This can be realized by performing an etching treatment with a treatment liquid composed of water (so-called SC1 composition solution).

That is, by using a treatment liquid consisting of ammonia water, hydrogen peroxide water, and pure water, etching treatment is performed for an arbitrary time, and a part of the semiconductor layer (silicon layer) is etched. Defects caused by Cu contamination and the like are excessively etched by the processing liquid and become large defects and become apparent.

In particular, if the defect selectivity is sufficient,
The type, composition and treatment conditions of the treatment liquid are not particularly limited, but for example, a solution of ammonia water-hydrogen peroxide water-water has an ammonia concentration of 0.3 to 3.0% by weight and a hydrogen peroxide concentration of It is preferably 0.15 to 0.6% by weight.
In particular, a solution in which the ratio of 28% ammonia water, 30% hydrogen peroxide water and water is adjusted to be 10: 2: 100 by volume is preferable. With the solution of SC1 composition, it is possible to reveal COP defects, defects due to polishing flaws, metal contamination, etc., but when treated with a solution of this concentration, the etching rate etc. becomes good, especially Cu etc. This is because defects due to contamination due to the above are likely to be revealed, and the etching amount can be easily controlled, and an etching process with an arbitrary thickness can be performed. By doing so, very small defects can be revealed.

Further, in an SOI wafer, since a light scattering type particle counter or the like which has been conventionally used because it has an insulating film or the like causes scattering noise, the manifested defects cannot be evaluated accurately. It is possible to evaluate by making secondary etch pits in the insulating layer by hydrofluoric acid treatment after performing the above treatment, but these secondary etch pits really reflect defects in the semiconductor layer. It's a matter of what you are doing. Therefore, in the present invention, evaluation is performed by using a laser microscope having a confocal optical system. By using such a microscope, the semiconductor layer can be evaluated in a state where the influence of the insulating film is small.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to Examples, but it goes without saying that these Examples are shown by way of illustration and should not be construed as limiting. An SOI wafer in which the semiconductor layer is silicon, the insulating layer is a silicon oxide film, and the supporting substrate is silicon is described below as a typical wafer having an SOI structure.

The evaluation procedure of the present invention will be described with reference to the drawings. As shown in FIG. 1, an inspected wafer (SOI wafer) is first prepared. The evaluation method of the present invention is
It can be used for SOI wafers manufactured by various methods and manufacturing conditions. However, since the evaluation method of the present invention is basically a destructive inspection, an inspected wafer is extracted from a plurality of SOI wafers manufactured under the same conditions,
It is evaluated as a representative quality.

Next, the defects in the semiconductor layer of the prepared wafer to be inspected are revealed. This is carried out by placing a treatment liquid for revealing minute defects, for example, minute defects caused by metal contamination such as Cu, in a container, and immersing a wafer to be inspected (SOI wafer) therein. In other words, the evaluation method of the present invention is applied to the SOI wafers manufactured by the various methods previously prepared, with a treatment liquid having selectivity for defects in the semiconductor layer, such as ammonia if the semiconductor layer is silicon. Etching is performed with a treatment liquid containing water and hydrogen peroxide. By performing such a pretreatment, a part of the semiconductor layer (silicon layer) is removed by etching, and this etching reveals microscopic defects. In particular, excessively (selectively) etching is performed in a portion having a defect caused by Cu or the like, and the defect becomes apparent on the pit.

The treatment liquid used at this time may be appropriately selected depending on the material of the semiconductor layer and the defect to be detected (for example, metal-induced defect, COP, stacking fault, etc. are not particularly limited), but it is not particularly limited. When silicon is silicon and the insulating layer is a silicon oxide film, a treatment liquid composed of aqueous ammonia, aqueous hydrogen peroxide, and water (SC1 composition solution) is preferable. By subjecting the surface of the SOI wafer to etching treatment for a long time using this treatment liquid, various fine defects existing in the semiconductor layer (silicon layer) are exposed while the semiconductor layer (silicon layer) is being etched. It becomes detectable.

Particularly, when the ammonia concentration of the treatment liquid is 0.
3-3.0 wt%, hydrogen peroxide concentration 0.15-0.6
It is preferable that it is wt%. For example, a treatment liquid consisting of ammonia water-hydrogen peroxide water-water is 28% ammonia water,
The ratio of 30% hydrogen peroxide water and water is 10: 2: 10, respectively.
It is preferable that the solution is adjusted at a volume ratio of 0. In particular, it is suitable for revealing defects caused by Cu or the like.
The treatment liquid having the SC1 composition has selectivity for such microscopic defects.

After such treatment, defects are evaluated in the present invention without forming secondary etch pits in the insulating layer portion by hydrofluoric acid treatment as in the prior art. That is, the SOI wafer after being treated with a treatment liquid for revealing microscopic defects (a treatment liquid containing ammonia water-hydrogen peroxide water-water or the like) is evaluated by a laser microscope of a confocal optical system.

FIG. 5 is a schematic explanatory view showing the basic structure of a laser microscope with a confocal optical system used in the present invention. In FIG. 5, 10 is a laser microscope with a confocal optical system, and a laser light source 14 such as an argon laser is provided corresponding to the microscope body 12.

The microscope body 12 has a beam splitter 16 for splitting a laser beam B from a laser light source 14 into a plurality of laser beams B, and a laser beam B on the surface (semiconductor layer) of a wafer W such as an SOI wafer to be inspected.
Objective lens 18 for converging light, a condenser lens 22 for converging a laser beam B reflected from the surface of the wafer W to a pinhole 20a of a pinhole member 20, and a photodetector for receiving the laser beam B passing through the pinhole 20a. It is composed of 24.

Next, the operating principle will be described below. The laser beam B from the laser light source 14 is split into a plurality of laser beams B by the beam splitter 16. Next, all the laser beams B are converted into S by the objective lens 18.
It converges on the surface (semiconductor layer) of the OI wafer W and irradiates the wafer surface with a spot of, for example, about 0.4 μm, and at the same time, scans in the horizontal direction while keeping the intervals of all the laser beams constant.

The laser beam B reflected from the surface of the SOI wafer W returns through the optical system, is converged by the condenser lens 22, passes through the pinhole 20a of the pinhole member 20, and enters the photodetector 24. When the semiconductor layer of the SOI wafer W, the insulating layer, or the supporting substrate has a defect, the wavefront of the reflected light from the defective portion is disturbed, and the spot of the laser beam B spreads at the photodetector 24. The light detection signal drops. The defect detection circuit (not shown) detects a signal difference in the photodetector 24 to detect a portion where a signal intensity difference equal to or more than a set value (threshold value) occurs as a defect portion. The inspection is performed while moving at a uniform speed, and each beam spot scans the entire wafer W minutely. A laser microscope having the configuration of the conformal optical system as described above is used. The laser microscope of such a confocal optical system is used to observe the detection and distribution of defects (defect density).

As described above, the semiconductor layer of the SOI wafer is first pretreated to reveal the defects, and then the revealed defects are evaluated by using the laser microscope of the confocal optical system to evaluate the defects of the SOI wafer. Quality can be evaluated accurately and easily.

(Example) An SOI wafer was prepared. This wafer is an SOI wafer which is considered to be Cu-contaminated, and the thickness of the supporting substrate (silicon substrate) is 725 μm.
The insulating layer (silicon oxide film) is a 165 nm SOI semiconductor wafer and the semiconductor layer (silicon layer) is a 165 nm SOI wafer.

This is etched using a treatment liquid consisting of aqueous ammonia and aqueous hydrogen peroxide. The treatment liquid is a solution of ammonia water-hydrogen peroxide water-water, and the ratio of commercially available 28% ammonia water, commercially available 30% hydrogen peroxide water and pure water is about 10: 2: 100, respectively. It has been adjusted. This processing liquid is about 60 to 7 for silicon.
The etching rate is about 0 nm / 40 minutes. As a result, the semiconductor layer (silicon layer) is removed.

The SOI wafer was subjected to an etching treatment for about 40 minutes by using such a treating solution to remove the semiconductor layer (silicon layer) having a thickness of 65 nm. Although the amount of etching is not particularly limited, about 30% to 70% of the semiconductor layer (silicon layer) is removed. By performing the etching process to this extent, minute defects that are considered to be caused by metal contamination existing in the semiconductor layer become apparent. At this time, if the etching amount is as small as 30% or less of the thickness of the semiconductor layer, the defect may be insufficient to be revealed. Again 70
If it is more than 0.1%, since the semiconductor layer (silicon layer) itself is thin, the revealed defects may be removed by etching and the information may be lost.

Next, the wafer subjected to the etching treatment was evaluated with a laser microscope of a confocal optical system. As a laser microscope of a confocal optical system, MAGICS (trade name) manufactured by Lasertec Corporation using an argon laser of 488 nm was used to evaluate the SOI wafer which was subjected to the above treatment.

The evaluation results are shown in FIG. FIG. 2 is a map showing the defect distribution evaluated by the evaluation method of the present invention. As can be seen from this figure, defects are dense (D1
And D2) are observed.

By the way, FIG. 3 shows an example in which an evaluation was carried out by a laser microscope of a confocal optical system before the treatment with a treatment liquid of ammonia water and hydrogen peroxide water. This figure is simply observed with a laser microscope of a confocal optical system without any treatment on the SOI wafer. Thus, although defects were observed even when the SOI wafer was simply evaluated, the dense defects as seen in FIG. 2 could not be observed. It can be seen that a new defect becomes apparent by performing the treatment with the treatment liquid of the ammonia water and the hydrogen peroxide water as in the present invention.

Next, the dense defects shown in FIG.
Observed by. The AFM is a measuring means that can accurately observe irregularities. The results are shown in FIGS. 4 (a) and 4 (b).
FIG. 4A is an AFM observation result of a part of the defects (a typical defect) observed in the portion D1 of FIG.
(B) is the observation result by AFM of a part of the defects (representative defect) observed in the portion D2 of FIG. As can be seen from the figure, the dense defects observed after the etching treatment are pit-like defects. This is metal,
Especially, it is often observed when there is Cu contamination.

When the above etching treatment is evaluated by a conventional light scattering type particle counter, the semiconductor layer of the SOI wafer is very thin, and scattering which is considered to be an influence of the interface of the insulating layer is generated to cause the background. It became noise and could not be evaluated accurately.

The present invention is not limited to the above embodiment. The above-mentioned embodiment is an exemplification, and it has substantially the same configuration as the technical idea described in the scope of claims of the present invention, and any one having the same operation and effect of the present invention Included in the technical scope

For example, in the evaluation method of the present invention, an SOI wafer is treated with a treatment solution of ammonia water and hydrogen peroxide solution and observed with a laser microscope of a confocal optical system, whereby defects caused by contamination as described above are obtained. We observed the abnormal distribution of the defects, and compared the number of defects before and after treatment with a treatment solution of ammonia water and hydrogen peroxide water, and quantified the defects that were revealed by performing such treatment. The SOI wafer may be evaluated by using the above method.

Further, in order to reveal defects that are considered to be caused by metal contamination in the semiconductor layer, a treatment solution of ammonia water and hydrogen peroxide solution was used in the embodiment of the present invention. As long as it has a property, another processing solution may be used.

The evaluation method of the present invention mainly evaluates defects due to metal contamination in the semiconductor layer, but other defects can be carried out as long as the defects can be revealed by an arbitrary treatment liquid.

Further, SO which can be evaluated by the evaluation method of the present invention
The I-wafer is not limited to one in which the semiconductor layer, the insulating layer, and the supporting substrate are made of silicon or a silicon oxide film, and an I-wafer made of a compound semiconductor or the like can be used. For example,
The support substrate may have silicon, the insulating layer may have a silicon oxide film, and the semiconductor layer may have GaAs or the like. Other materials may be used.

[0053]

The effects of the typical ones of the present invention will be described. First, a semiconductor layer of an SOI wafer is pretreated to reveal defects, and then this is revealed using a laser microscope of a conformal optical system. The quality of the SOI wafer can be evaluated accurately and easily by evaluating the defects.

For example, if the semiconductor layer is silicon, S
The quality of the SOI wafer can be easily evaluated by etching the OI wafer with a treatment solution consisting of ammonia water and hydrogen peroxide water, removing a part of the semiconductor layer, and then evaluating with a laser microscope with a confocal optical system. I can do things.

Particularly, in the evaluation method of the present invention, information on metal contamination such as Cu contamination can be obtained.
The yield of the device process can be improved by not flowing the OI wafer to the device process. Also SO
It is possible to accurately evaluate the contamination status of the I wafer manufacturing process,
It is also possible to improve the manufacturing process of SOI wafers.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating an evaluation procedure of the present invention.

FIG. 2 is a map diagram showing a defect distribution of a wafer evaluated by an evaluation method of the present invention.

FIG. 3 is a map diagram showing a defect distribution of a wafer evaluated by a laser microscope of a confocal optical system before treatment with a treatment liquid of ammonia water and hydrogen peroxide water.

FIG. 4 is a view in which dense defects detected by the present invention are observed by AFM.

FIG. 5 is a schematic explanatory view showing a basic structure of a laser microscope using a confocal optical system.

[Explanation of symbols]

10: Laser microscope with confocal optical system, 1
2: Microscope body, 14: Laser light source, 16: Beam splitter, 18: Objective lens, 20: Pinhole member, 2
0a: Pinhole, 22: Condensing lens, 24: Photodetector 24, B: Laser beam, W: Wafer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // G01N 13/16 G01N 1/28 F

Claims (5)

[Claims] 1. A method for evaluating an SOI wafer in which a semiconductor layer, an insulating layer, and a supporting substrate are sequentially formed, in which defects existing in the semiconductor layer are revealed and evaluated by a laser microscope of a confocal optical system. A method for evaluating a characteristic SOI wafer. 2. A method for evaluating an SOI wafer in which a semiconductor layer, an insulating layer, and a supporting substrate are sequentially formed, wherein the SOI wafer is etched with a treatment liquid consisting of ammonia water and hydrogen peroxide water, A method for evaluating an SOI wafer, which comprises performing evaluation with a laser microscope having a confocal optical system after removing a portion. 3. A semiconductor layer of an SOI wafer is silicon,
The method for evaluating an SOI wafer according to claim 2, wherein the insulating layer is a silicon oxide film. 4. The treatment liquid comprising ammonia water and hydrogen peroxide water is a solution in which the ratio of 28% ammonia water, 30% hydrogen peroxide water and water is adjusted to a volume ratio of 10: 2: 100, respectively. The method for evaluating an SOI wafer according to claim 2 or 3, wherein 5. The SOI according to claim 1, wherein the presence of metal contamination is evaluated.
Wafer evaluation method.