JP2002151560A - Method and apparatus for measuring internal defect of semiconductor wafer as well as manufacturing method for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method for the internal defect of a semiconductor wafer in which chemicals such as a weak acid or the like are not required, and in which the internal defect can be measured with high sensitivity even in the semiconductor wafer of low reistivity. SOLUTION: A measuring cross section IP which exposes the inside of the semiconductor wafer 1 is formed in the semiconductor wafer 1. A light beam LB for defect detection is made incident on the measuring cross section IP. Response light DB from the cross section IP based on the beam LB is detected. On the basis of information on the response light DB, a defect which exists inside the semiconductor wafer 1 is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring internal defects in a semiconductor wafer, a method for manufacturing the semiconductor wafer, and an apparatus for measuring internal defects in a semiconductor wafer.

[0002]

2. Description of the Related Art A semiconductor wafer (for example, a silicon single crystal wafer) is accurately measured and evaluated because the distribution of internal defects greatly affects the yield and characteristics of semiconductor devices manufactured from the wafer. This is very important in the production of semiconductor wafers. For example, when a silicon single crystal wafer manufactured by a known method such as a CZ method (Czochralski Method) is subjected to a heat treatment, as shown in FIG. 1, a BMD (Bulk While a Micro Defect) layer is formed, a DZ (Denuded Zone) layer in which a precipitate has disappeared due to outward diffusion of oxygen during heat treatment is formed on the surface layer portion. When a silicon device is formed mainly in a surface layer portion of a silicon single crystal wafer, it is advantageous from the viewpoint of reducing occurrence of defects that a device formation region does not cover a BMD layer as much as possible. On the other hand, as long as the device formation region remains in the DZ layer, oxygen precipitates in the BMD layer are IG (Intr
Since it functions as an insic gettering (site) site, it is necessary to form the DZ layer and the BMD layer in a well-balanced manner in order to utilize the site positively.

Conventionally, there are two known methods for measuring internal defects in a semiconductor wafer. One is a selective etching method, and the other is an optical method using light scattering or light interference. In the selective etching method, first, the inside of a semiconductor wafer to be evaluated is exposed by cleavage or oblique polishing, and the exposed surface is corroded by an appropriate etching solution. Then, a portion where a strain such as a defect is generated has a difference in an etching rate between a sound portion having a small distortion and the etched portion, so that the portion is etched in the form of an etch pit. By detecting this etch pit, the state of defect formation inside the semiconductor wafer can be known.

On the other hand, in an optical method using light scattering or light interference, an incident light beam such as a laser beam is made incident from the surface of the wafer, and light scattered or interfered by a defect is formed on the back surface of the wafer or separately. It can be taken out from the cleavage plane or the like and detected, and the defect formation state inside the semiconductor wafer can be known based on the information of the detected light.

[0005]

However, the above-mentioned conventional method has the following disadvantages. First, in the selective etching method, a chromic acid-based one such as a light solution or a Zirtolue solution has been used as the etching solution. However, from the viewpoint of environmental protection, a non-chromic acid-based one such as a JIS-H solution has been used. is there. However, a non-chromic acid-based etching solution uses a strong acid such as hydrofluoric acid or nitric acid, which is troublesome to handle, and has a problem that detection accuracy is not high due to low selectivity of etching with respect to defects. In particular, in a low resistivity wafer having a high dopant concentration (especially 0.02 Ω · cm or less), the selective etching property for defects is extremely poor. Almost undetectable.

On the other hand, in the case of an optical method utilizing light scattering or light interference, in the case of a semiconductor wafer having a main surface on which a device pattern is formed or a rough surface, incident light is affected by the pattern and irregularities. At the same time, there is a problem that accurate internal defect measurement cannot be performed. In addition, in order to know the defect distribution in the thickness direction of the wafer, it is necessary to take and analyze a stereo defect image, so that the mechanism of the optical system of the measuring apparatus and the analysis program tend to be complicated, and there is a disadvantage that a measurement error tends to occur. Furthermore, since the incident light beam passes through the inside of the semiconductor wafer for a long distance, light scattering or absorption due to free electrons occurs on a wafer having a low resistivity, so that it is difficult to avoid a decrease in the detection signal level, and defect detection is performed. Accuracy tends to decrease. In particular, when the resistivity is reduced to 0.005 Ω · cm or less, defect detection itself becomes impossible.

An object of the present invention is to provide a method for measuring an internal defect of a semiconductor wafer which does not require a chemical such as a strong acid and which can measure an internal defect with high sensitivity even in a semiconductor wafer having a low resistivity. And a method for measuring an internal defect of a semiconductor wafer.

[0008]

In order to solve the above-mentioned problems, a method for measuring an internal defect of a semiconductor wafer according to the present invention comprises forming a measurement section on a semiconductor wafer to expose the inside of the semiconductor wafer. Then, an incident light beam for defect detection is incident on the measurement section, response light from the measurement section based on the incident light beam is detected, and a defect existing inside the semiconductor wafer is detected based on information of the response light. The measurement is performed. Here, the response light is the light emitted from the measurement cross section based on optical interaction such as scattering, interference, photoluminescence and diffraction between the incident light beam and the measurement cross section forming portion of the semiconductor wafer. Among these, those which cause a difference in an optical state such as intensity, wavelength or emission direction between a defect forming portion of a semiconductor wafer and a sound portion which is not particularly formed such as a defect.

According to the above method, as shown in FIG.
A measurement section IP for exposing the inside of the semiconductor wafer 1 to be measured is formed, an incident light beam for defect detection is incident on the measurement section IP, and the semiconductor wafer 1 is determined based on information of response light from the measurement section. Since the measurement of defects existing in the inside is performed, it is not necessary to use a troublesome chemical such as a strong acid as in the selective etching method. Further, even if irregularities or steps are formed on the main surface MP of the wafer such as the device pattern DP, the defect can be measured and evaluated without being affected at all. Furthermore, the defect distribution in the thickness direction of the wafer can be easily measured by simply manipulating the incident light beam in the thickness direction on the measurement cross section. For example, complicated optical systems and analysis such as taking and analyzing stereo defect images are possible. No programs are required. Also,
Since the incident light beam does not pass through the wafer for long distances,
It is hardly affected by light scattering or absorption by free electrons and cannot be measured by conventional selective etching or optical methods.
Even with a low resistivity wafer of 005 Ω · cm or less, defects can be detected with high accuracy, and the detection accuracy of minute defects can be increased.

Next, a method of manufacturing a semiconductor wafer according to the present invention is characterized in that internal defects of a semiconductor wafer are measured by the above-described measuring method of the present invention, and the semiconductor wafer is sorted based on the measurement result. That is, by employing the measurement method of the present invention, internal defects of a semiconductor wafer can be detected with high accuracy and easily. The defect rate of the wafer product lot is reduced, and the quality can be improved.

In the present invention, response light is detected at a plurality of positions on the measurement cross section by two-dimensionally scanning the irradiation position of the incident light beam with respect to the measurement cross section, and information of the response light at each of these positions is added to the information. Based on this, the defect distribution state in the thickness direction of the semiconductor wafer can be measured. This makes it possible to easily and accurately measure the state of defect distribution inside the semiconductor wafer, and is effective for, for example, measuring the thickness of the DZ layer or BMD layer formed inside the semiconductor wafer.

When the thickness of the wafer to be measured is small, as shown in FIG. 2, the measurement section IP is formed as an inclined section inclined with respect to the main surface MP, so that the thickness in the thickness direction can be increased. The magnification can be increased, which is effective in increasing the accuracy of defect measurement. Further, even when the DZ layer 2 or the BMD layer 3 is formed on the semiconductor wafer and the thickness of the DZ layer 2 is considerably small, the cross sections 2 ′ and 3 ′ of each layer in the inclined cross section IP are the distances in the thickness direction. Appears in an enlarged manner, so that accurate measurement is possible.

Further, the apparatus for measuring internal defects of a semiconductor wafer according to the present invention is a wafer holder for holding a semiconductor wafer having a measurement section for exposing the inside so that the measurement section is parallel to the scanning plane of the incident light beam. And an incident light beam generating unit that impinges an incident light beam for defect detection on a measurement section of the semiconductor wafer held by the wafer holder, and response light that detects response light from the measurement section based on the incident light beam A detector and an incident light beam scanning mechanism for two-dimensionally scanning the irradiation position of the incident light beam with respect to the measurement section by moving the wafer holder together with the semiconductor wafer in the scanning plane with respect to the incident light beam; A method for outputting measurement information of a defect existing inside a semiconductor wafer based on information of response light at a plurality of positions on a measurement cross section. An information output unit, characterized by comprising a.

According to the above-described apparatus, the above-described defect measuring method of the present invention and a method of manufacturing a semiconductor wafer can be rationally and efficiently performed, and the defect distribution information on the measured cross section can be obtained with high accuracy and efficiency. Can be measured. Further, the semiconductor wafer on which the above-described measurement cross section is formed is held by the wafer holder so that the measurement cross section is parallel to the scanning plane of the incident light beam, and in this state, the wafer holder is held together with the semiconductor wafer against the incident light beam. Since the irradiation position of the incident light beam with respect to the measurement section is two-dimensionally scanned by being relatively moved within the scanning plane, for example, the measurement section is formed as an inclined section inclined with respect to the main surface of the wafer. Even if it is, the distance from the incident light beam generation unit to the incident light beam irradiation position can be kept constant irrespective of the scanning position by making this coincide with the scanning plane, and the configuration of the scanning drive system can be simplified. Can be

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a silicon single crystal wafer (hereinafter simply referred to as a wafer) 1 as a semiconductor wafer. The wafer 1 is formed by processing a silicon single crystal ingot manufactured by the CZ method or the like into a wafer by a normal method and then performing a predetermined heat treatment. And the DZ layers 2 and 2 with few defects are formed.
BMD where defects such as oxygen precipitates exist at a predetermined level
A layer is formed.

As shown in FIG. 2, with respect to the wafer 1,
A measurement section IP exposing the inside is formed. In the present embodiment, the measurement section IP is formed as an inclined section inclined at a certain angle α with respect to the main surface MP (hereinafter, the inclined section I
P). Such an inclined cross section IP can be formed by a so-called oblique polishing method. FIG. 3 shows an example of the polishing apparatus. As shown in FIG. 3A, a polishing platen 216 covered with a polishing cloth 10 and rotated around a rotation axis O, and a wafer 1 is adhered to the lower surface side. It has a polishing jig 11 to be attached and fixed, and a jig holder 217 for holding the polishing jig 11 on a polishing platen 216.
A wafer fixing surface 12 is formed on the polishing jig 11, and FIG.
As shown in the figure, here, the second main surface MP2 of the wafer 1
Is fixed via a wax layer 13 or the like. On the other hand, the jig holder 217 is formed in a cylindrical shape, and the polishing jig 11 is inserted inside, so that the first main surface MP1 of the wafer 1 is
0 so that the polishing jig 11 is pressed against the polishing platen 2.
16 is held. When the polishing table 216 is rotated, the jig holder 217 rotates with the polishing jig 11 and the wafer 11 fixed thereto.

The surface GP of the polishing cloth 10 is orthogonal to the rotation axis O, while the wafer fixing surface 12 is formed to be inclined by an angle α with respect to the cloth surface GP. Here, the wafer 1 is fixed, and the polishing jig 11 is inserted into the jig holder 17 so that the polishing cloth 10 and the wafer 1 are brought into contact with each other. When the wafer 16 is rotated, the first main surface MP1 of the wafer 1 is obliquely polished as shown in FIG.
An inclined cross section IP inclined by an angle α with respect to P1 is formed. In the inclination direction of the inclined cross section IP, the distance in the thickness direction of the wafer 1 is enlarged by cosec α. For example, if α is set to 5 ゜ 44 ′, the magnification is about 10 times. In order to prevent the sagging of the polished side edge of the inclined cross section IP, as shown in FIG.
It is effective to affix the dummy material 19 to the first main surface MP1 side with wax or the like for polishing. The material of the dummy material 19 is not particularly limited as long as it is a material whose grinding property is substantially opposite to that of the wafer 1. For example, a silicon single crystal wafer or a material made of a hard resin can be used.

The inclined cross section may be formed by a cleavage method. For example, when the main axis of the wafer 1 is <100>, a cross section perpendicular to the main surface can be formed in the form of a cleavage plane using {110} cleavage.

As shown in FIG. 5, the wafer 1 having the inclined cross section IP is mounted on the wafer holder 14 so that the inclined cross section IP faces upward. As shown in FIG. 6, the wafer holder 14 holds the wafer 1 (or a measurement test piece cut out from the wafer 1) so as to be parallel to the scanning surface of the incident light beam LB. In the example shown in FIG. 5, a wafer mounting portion 15 for detachably holding the wafer 1 is formed on the upper surface of the wafer holder 14 as a shallow concave portion into which the wafer 1 is fitted. The bottom surface of the concave portion is a wafer holding surface HP inclined by an inclination angle α of an inclined cross section IP with respect to a reference surface BP (parallel to a scanning surface described later) forming a lower surface of the wafer holder 14. Then, the wafer 1 is
Is mounted such that the second main surface MP2 is in contact with the wafer holding surface HP, so that the wafer 1 has an inclined cross section I
P is held so as to be substantially parallel to the reference plane BP.

As shown in FIG. 6, the above-mentioned wafer holder 14 and the wafer 1 together with the scanning X
-Y table 18 (X table 20 for X direction movement,
Y table 21 for moving X table 20 in the Y direction
). On the upper surface of the XY table 18, a holder mounting portion 20a (here, formed as a shallow recess, but not limited thereto) having a holding surface KP parallel to the scanning surface CP is formed.
Reference numeral 4 is mounted here so that the reference surface BP contacts the holding surface KP. As a result, the inclined cross section IP of the wafer 1 becomes X
The -Y table 18 enables the independent movement in the X direction and the Y direction crossing each other (for example, orthogonal to each other) in parallel with the scanning plane CP.

Then, the incident light beam generating unit 30 irradiates the inclined cross section IP with the incident light beam LB for defect detection while changing the position, and the response light DB from each position is transmitted to the response light detecting section 117. Is detected by The incident light beam generating unit 30 is, for example, a laser emitting unit as shown in FIG. 7, and generates an infrared laser or a visible light laser beam having a predetermined wavelength. This laser light is applied to the inclined section IP by the objective optical system 35 in such a manner that the laser beam is narrowed down to a laser beam having a predetermined diameter d. Laser light wavelength λ
The beam diameter d and the beam diameter d are appropriately selected depending on the type and size of the defect to be detected. Particularly, in a region near the edge of the inclined cross section (measurement cross section) IP on the first main surface MP1 side, the ridge formed at the edge or the It is effective to narrow the beam diameter d to, for example, about 1 to 5 μm in order to make it difficult to cause irregular reflection due to the pattern originally formed on the one main surface MP1. Use the converted diameter).

Returning to FIG. 6, the response light detecting section 117 can be constituted by a photomultiplier, a photodiode or a CCD sensor. The response light can be, for example, scattered light at the inclined cross section IP. In this case, if a defect (that is, an internal defect) exists on the inclined cross section IP, a difference in scattered light intensity is generated between the defect and the portion where no defect exists. Accordingly, in this case, the response light detection unit 117 is configured to detect the total intensity of the generated scattered light at each position.

On the other hand, photoluminescence emission from a measurement section by an incident light beam can be used as response light. In this case, defect detection can be performed by utilizing the fact that the intensity and wavelength of photoluminescence emission at the defect existing portion are different from those of other portions. In this case, the response light detection unit 117 is configured to detect the total intensity of photoluminescence emission at each position. If the photoluminescence emission wavelength is unique at the defective portion, the spectroscope should be configured to selectively detect only light of the corresponding wavelength. For example, in a defect portion where heavy metal atoms are easily adsorbed, a light emission wavelength specific to the adsorbed heavy metal atoms is generated. Is effective in performing defect detection.

When using the above-described photoluminescence method, it is desirable to use a strong excitation microphotoluminescence method as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-274257. This means that the spot diameter is 1-2μ
m (approximately 0.1 to 1 mm in diameter in a normal photoluminescence method), and the laser power is 20 to 100 mW at the measurement position, which is several to several tens times higher than the normal photoluminescence method. is there. This excitation conditions, the energy density of the excitation laser is high 10 ⁵ times the normal photoluminescence method. Under the excitation conditions of the photoluminescence method, the carrier diffusion length is as long as several hundred μm, and the spatial resolution of the photoluminescence light (band edge emission) is also several hundred μm.
m. On the other hand, in the strong excitation microphotoluminescence method, the carrier diffusion length is suppressed to the order of several μm by using the above-described strong excitation conditions, and photoluminescence light measurement with high spatial resolution (up to 1 μm) becomes possible. Detection accuracy can be improved. Here, the band edge emission intensity in the strong excitation microphotoluminescence method is represented by the following equation. I _b ∝n _ex ² τ (where, I _b : band edge emission intensity, n _ex : injected carrier concentration, τ: lifetime)

FIG. 8 shows an example of the electrical configuration of the measuring apparatus 100, which has a control computer 111 and a measuring system 101 connected thereto. The control computer 111 has an I / O port 108 and a C
A PU 104, a ROM 105, a RAM 106, a hard disk drive (hereinafter abbreviated as HDD) 107 as a storage device, and a keyboard 109 and a mouse 110 as input devices are connected. In the HDD 107,
Control program 10 for controlling the operation of the particle detection device
7a, a data capturing program 107b for capturing crystal defect data, and a captured crystal defect data file 107c are stored. Also, the RAM 106
, Work areas 106a and 106b for the control program 107a and the data fetching program 107b, and a fetched crystal defect data storage area 106c are formed.

Next, the measuring system 101 includes the incident light beam generating unit 30 (FIG. 6), the response light detecting unit 117, and a driving unit for driving the XY table 18 (FIG. 6). Have. The driving unit is, specifically, an X table 2
0 and the Y table 21 (FIG. 6) via an unillustrated screw shaft mechanism or the like, an X drive motor 113 and a Y drive motor 115, and a pulse generator for servo control of these motors and detecting a rotational angle position. (Hereinafter, X-
PG) 114 and a pulse generator (hereinafter Y)
-PG) 116. The X drive motor 113 and the Y drive motor 115 are respectively connected to the I / O port 1 of the control computer 111 via a motor driver (not shown).
08, and is driven and controlled by execution of the control program 107a. Although the scanning method is XY scanning here, spiral scanning may be adopted.

On the other hand, a detection level output of the response light detected by the response light detection unit 117 is input to the data interface 103. On the other hand, pulse generators 114 and 11
6 is output through the data interface 103 via the I / O
The input is made to the port 108. The data interface 103 is, for example, as shown in FIG.
X-counters 103a and Y- which count up upon receiving pulse signals from PG114 and Y-PG116
It has a counter 103b, a gate IC 103c, a comparator 103d, and the like. Each counter 103a, 103
The count output of b gives the measurement position by the incident light beam generation unit 30 uniquely. Then, the intensity of the response light at the measurement position is determined by the X coordinate and the Y coordinate of the defective image pixel.
The counter outputs are input to the I / O port 108 via the gate IC 103c. The outputs of the counters 103a and 103b are a plurality of bits, but are drawn with one line for simplification.

On the other hand, the comparator 103d compares the detection level output of the response light with the threshold level Vref, and when the detection level output exceeds Vref, the gate IC 103d.
A data capture permission signal is output to the inhibit input terminal of c. As a result, the gate IC 103c provides the control computer 111 with the count outputs of the counters 103a and 103b, that is, the X coordinate and Y coordinate of the defective image pixel.
Coordinate data is allowed to be captured via the I / O port 108. The data capturing process is performed by the data capturing program 107b, and the captured data is stored in the crystal defect detection point data file 107c. Although not shown in FIG. 9, a flip-flop that latches and holds the counter output until the data fetch is completed can be provided at the subsequent stage of the counter output.

Hereinafter, the flow of the operation of the measuring apparatus 100 will be described using a flowchart. FIG. 10 shows a flow of the inspection processing in the measuring apparatus 100. This process is performed by the CPU 104 of the control computer 111 by executing the detection device control program 107a. First, in S1, wafer identification data such as a product number, a lot number, and a production date of a wafer to be measured are input.
Next, in S2 and S3, as shown in FIG. 6, the wafer 1 is mounted together with the wafer holder 14, and when the mounting is completed normally, the process proceeds to a measurement process.

Returning to FIG. 10, in S4, the X drive motor 113 and the Y drive motor 115 shown in FIG. 3 are operated, and the position of the wafer holder 14 (hereinafter referred to as the holder position) is previously determined on the (X, Y) coordinates. The X-counter 103a and the Y-counter 103 are moved to the determined origin position, and the X-reset signal and the Y-reset signal shown in FIG.
Reset b. Hereinafter, while scanning the irradiation position of the incident light beam LB on the XY coordinate plane with the X direction as the horizontal direction and the Y direction as the vertical direction, the incident light beam L
Irradiation of B is performed to detect response light. That is, in S5, the Y coordinate value Yk is set to be the first scanning position Y1 in the Y direction, and in S6, the Y coordinate value Xk is set to be the first scanning position X1 in the X direction. As a result, the laser beam probe moves to the first measurement position (X1, Y1).

Then, in S7, the wafer is held at the measurement position for a certain period of time, the main surface is irradiated with the incident light beam LB, and the response light is detected. For example, when light scattering or photoluminescence is used, if the intensity signal level of the response light is higher than a reference value (threshold) Vref, the pixel at that position is determined as a pixel of the defect existing part, otherwise, the defect non-existent part Pixel. Further, the counter values of the X-counter 103a and the Y-counter 103b at that time are taken in as X coordinate data and Y coordinate data of each pixel (S8, S9). In this way, bitmap defect image data described as a set of binary pixel data is obtained. The fetched data is stored in the crystal defect detection point data storage area 106c of the RAM 106 in FIG. In this flowchart, the step of comparing with the threshold value is represented as S8 for convenience, but this comparison step is actually performed by hardware in the data interface 103 of FIG. 9 (however, the control program 107a It goes without saying that it may be performed by software inside.) Note that the intensity signal level of the response light may be divided into three or more stages, and the defect image data may be generated as gradation data.

In S10, it is determined whether or not the measurement position has reached a limit position XN in the X direction. If it has not arrived, the process proceeds to S11, in which the value of the measurement position coordinate Xk in the X direction is increased to the next coordinate value Xk + 1 while the value of the measurement position coordinate Yk in the Y direction is fixed, and the measurement position is moved. And returns to S7 to repeat the following processing up to S9.
On the other hand, if the measurement position has reached the limit position XN in the X direction in S10, the process proceeds to S12, and it is similarly determined whether or not the measurement position has reached the limit position YN in the Y direction. S if not reached
At 13, the value of Yk is increased to the next coordinate value Yk + 1, and the process returns to S6 to return the value of Xk to the initial value X1. Thereafter, the process returns to S7 and repeats the following processes up to S9. On the other hand, S13
If the value of Yk has reached YN in this case, it means that the measurement at all the measurement positions has been completed, and the process exits the data acquisition loop and proceeds to S14.

For example, FIG. 11 shows an example of defect image data obtained by using the light scattering method. Although the defect portion is a black region, the size of the defect region varies because each defect has a different size. For example, when it is desired to obtain a defect formation density, defect distribution data including position information of each defect is required. In this case, each defect area is separated from the defect image data by a known labeling method, and the defect position is determined for each area according to a predetermined definition (for example, a geometric center of gravity position). . The defect image data or defect distribution data obtained in this way is stored as a crystal defect data file 107c in the HDD 10 in a form corresponding to the wafer specifying data.
7 is stored.

The defect measurement information based on the stored contents of the crystal defect data 204c is stored in, for example, the printer 120 shown in FIG.
And a monitor 121 (measurement information output unit). For example, in the case of the sampling inspection, it is possible to output the product number, the lot number, the manufacturing date of the wafer, and the number of detection points for each crystal defect type. For example, when the count number of crystal defects of a specific type exceeds a predetermined limit value, the product lot to which the wafer belongs is determined to be defective, and can be sorted out from non-defective products.

[0035]

EXAMPLES The following experiments were conducted to confirm the effects of the present invention. The following two types of p-type silicon single crystal wafers (diameter 200 mm) were prepared as wafers to be evaluated. Resistivity 0.01Ω · cm, initial oxygen about 14ppma
(JEIDA (Japan Electronics Industry Promotion Association) standard). 850
The oxygen precipitate forming heat treatment is performed at 8 ° C. for 8 hours and at 1000 ° C. for 16 hours. Resistivity 10 Ω · cm, initial oxygen about 16 ppma (JE
IDA standard). The oxygen precipitate forming heat treatment is performed at 850 ° C. for 0.5 hour, at 800 ° C. for 36 hours, at 1000 ° C. for 2 hours, at 650 ° C. for 3 hours, and at 900 ° C. for 2 hours.

As shown in FIG. 12, two samples each having a width of 4 mm were cut out from each of these wafers as shown in FIG. 12 and polished obliquely by the method shown in FIG. The other was used as a sample for selective etching of the comparative example. The sample for the present invention is a semiconductor laser (wavelength 980 nm, emission energy 1 mW)
Is used as an incident light beam, and scattered light is used as a response light.
Alternatively, the defect image at the inclined cross section IP was measured by the apparatus 100 shown in FIG. On the other hand, the sample for selective etching is a non-chromic acid JIS-H
The inclined cross section IP was etched using the liquid, and the surface after the etching was observed with an optical microscope. FIGS. 13 and 14 are images of defects obtained for each of the wafers (each having a magnification of 200), wherein (a) is obtained by selective etching and (b) is obtained by the method of the present invention. In FIG. 13, it can be seen that, although the wafer is a low resistivity wafer, it is almost impossible to identify a defect by selective etching, whereas a clear defect image is obtained by the method of the present invention. In FIG. 14, although the wafer is usually a resistivity wafer, the heat treatment simulates a low-temperature process, the internal defect size is small, and the etch pit is very unclear by the selective etching method. It can be seen that a clear defect image was obtained by the method.

[Brief description of the drawings]

FIG. 1 is a schematic view of a semiconductor wafer to be evaluated.

FIG. 2 is an explanatory diagram of an effect of an inclined cross section.

FIG. 3 is a schematic side view showing a method of performing an inclined cross section by oblique polishing.

FIG. 4 is a schematic side cross-sectional view illustrating a state in which a dummy material is used to prevent surface sagging of an inclined cross section.

FIG. 5 is a schematic cross-sectional side view showing a state where a wafer having an inclined cross section is attached to a wafer holder.

FIG. 6 is a schematic view showing a main part of a measuring apparatus using the wafer holder of FIG.

FIG. 7 is a schematic view showing an example of a laser emission unit.

FIG. 8 is a block diagram showing an example of an electrical configuration of the measuring device.

FIG. 9 is a circuit diagram showing a configuration example of a data interface of FIG. 8;

FIG. 10 is a flowchart showing a flow of an example of an inspection process using the measuring device of FIG. 8;

FIG. 11 is an image showing an example of a defect image obtained by the method of the present invention by a light scattering method.

FIG. 12 is an explanatory diagram showing a form of taking out a sample from a wafer used in an experimental example.

FIG. 13 is an image showing a defect image according to the present invention of a wafer of an experimental example in comparison with a comparative example by selective etching.

FIG. 14 is an image showing a defect image according to the present invention of a wafer of an experimental example in comparison with a comparative example by selective etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer IP Measurement cross section (inclined cross section) 14 Wafer holder 18 XY table (incident light beam scanning mechanism) 30 Incident light beam generating unit 100 Defect measuring device 117 Response light detecting section 120 Printer (measurement information output section) 121 Monitor (Measurement information output section)

Continued on the front page F-term (reference) 2F065 AA49 BB03 CC19 FF44 FF67 GG04 GG21 HH04 HH12 JJ01 JJ08 JJ17 JJ18 MM02 PP12 QQ03 QQ05 QQ23 QQ52 TT07 2G043 AA03 CA05 EA01 GA07 GB19 KA01 KA02 KA01 KA02 KA02 HH02 KK01 KK02 KK04 KK07 MM05 MM10 4M106 AA01 BA04 BA05 BA08 CB19 CB20 DH12 DH13 DH32 DH50 DH57 DJ04 DJ11 DJ21 DJ23

Claims (12)

[Claims] 1. A measuring section for exposing the inside of a semiconductor wafer is formed on a semiconductor wafer, an incident light beam for defect detection is incident on the measuring section, and a response from the measuring section based on the incident light beam is provided. A method for measuring an internal defect of a semiconductor wafer, comprising detecting light and measuring a defect present inside the semiconductor wafer based on information of the response light. 2. The response light is detected at a plurality of positions on the measurement cross section by two-dimensionally scanning the irradiation position of the incident light beam with respect to the measurement cross section, and information of the response light at each position is obtained. 2. The method according to claim 1, wherein a defect distribution state in a thickness direction of the semiconductor wafer is measured based on the measurement result. 3. The method according to claim 1, wherein the measurement section is formed as an inclined section inclined with respect to a main surface of the semiconductor wafer. 4. The method according to claim 3, wherein the inclined cross section is formed by obliquely polishing the main surface of the semiconductor wafer. 5. The method according to claim 1, wherein the measurement section is formed as a cleavage plane of the semiconductor wafer. 6. The method according to claim 1, wherein the incident light beam is a laser beam of infrared light or visible light. 7. The method according to claim 1, wherein scattered light from the measurement section due to the incident light beam is detected as the response light. 8. The method according to claim 1, wherein photoluminescence emission from the measurement section due to the incident light beam is detected as the response light. 9. The method according to claim 8, wherein the photoluminescence emission is detected using a strongly excited photoluminescence method. 10. The method according to claim 1, wherein the semiconductor wafer has a surface resistivity of 0.02 Ω · cm or less. 11. The method according to claim 1, wherein an internal defect of the semiconductor wafer is measured.
A method of manufacturing a semiconductor wafer, wherein the semiconductor wafer is sorted based on a result of the measurement. 12. A wafer holder for holding a semiconductor wafer on which a measurement section for exposing the inside is formed so that the measurement section is parallel to a scanning plane of an incident light beam, and the semiconductor held on the wafer holder. An incident light beam generation unit that impinges the incident light beam for defect detection on the measurement cross section of the wafer; a response light detection unit that detects response light from the measurement cross section based on the incident light beam; and the wafer holder The incident light beam scanning mechanism that two-dimensionally scans the irradiation position of the incident light beam with respect to the measurement cross section by moving the incident light beam relative to the incident light beam together with the semiconductor wafer in the scanning plane. Measuring a defect existing inside the semiconductor wafer based on information of the response light at a plurality of positions on the measurement cross section; Internal defect measuring apparatus of a semiconductor wafer, characterized in that it comprises a measurement information output unit for outputting the broadcast, the.