JP2003037138A - Notch inspecting method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for avoiding diameter increase of an ingot, troublesome handling due to an increase of weight, increase of hazards and an investment for new handling facilities and accurately, simply and easily estimating quality required for a shape of a notch, and an inspecting apparatus. SOLUTION: The shape of the notch 5 formed in a semiconductor wafer W is inspected. The notch inspecting method and apparatus vertically hold the wafer W by using a wafer holding means 7 and evaluate the shape of the notch 5 by using a probe 4 of a probing contour shape measuring instrument 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a notch formed on a semiconductor wafer and a notch inspecting apparatus.

[0002]

2. Description of the Related Art A semiconductor wafer is provided with an orientation flat (orientation flat) for facilitating identification and alignment of crystal orientation and conduction type. This is a flat surface provided on the outer circumference of the ingot and the wafer. Similarly to the orientation flat, a notch called a notch may be formed on the outer circumference of the ingot and the wafer in order to easily identify the crystal orientation and align the wafer. Especially in crystals with a diameter of 300 mm or more due to the recent increase in diameter, the area occupied by orientation flats increases,
Notch is the mainstream.

This notch needs to be formed along a specific orientation of the single crystal, and is usually formed at the ingot stage. That is, it is general that a single crystal is manufactured by the Czochralski method or the like, the outer periphery of a pulled single crystal ingot is cylindrically ground to make the diameter and the like uniform, and then a notch is formed by grinding or the like.

The notch shape at this ingot stage is an intermediate shape. That is, the final shape of the notch is formed in the chamfering process of the wafer after slicing. Therefore, the notch shape after cylindrical grinding did not need to be machined or inspected so precisely. However, in the sense of controlling the throughput (the number of substrates that can be processed in a unit time) in the chamfering process for forming the final notch shape, the wear of the grindstone, and the variation of the final shape, the intermediate shape after cylindrical grinding. The notch shape as is important. Particularly, the surface roughness has a great influence on the throughput of the chamfering process, and the notch depth and the like cannot be corrected by the chamfering process.

Generally, there are five notch measurement items: depth, angle, tip R, symmetry, and surface roughness. As an evaluation method, place the ingot on the ingot holding table,
There is a method of inspecting using a contact-type shape measuring means, or a wafer-shaped sample in which a notch portion is enlarged and projected by a projection method for evaluation.

Here, FIG. 4 is an explanatory view showing an example of a notch inspecting apparatus for inspecting a notch formed in an ingot. The notch inspection device 20 of FIG. 4 is a device for inspecting the shape of the notch 5 formed in the ingot G, and places the ingot G on the V-shaped holding table 11 with the notch 5 facing upward. Next, the contour of the ingot G and the contour of the notch 5 are scanned from the direction perpendicular to the crystal axis by the stylus 4 of the stylus type contour measuring device 2, and the X-axis and Z-axis coordinates are determined by the X-axis / Z-axis detector 3
And sends the coordinate data to a computer (not shown) to calculate analysis data of 5 items (depth, angle, tip R, symmetry, surface roughness) related to the notch 5 with the analysis software,
Output the notch shape to a CRT or printer.

[0007]

With the increase in diameter in recent years, when notch inspection is performed in an ingot state, a heavy weight ingot is handled, which imposes a great burden on the operator who inspects the notch. ing. For example, when an ingot is placed on a V-shaped holding table as shown in FIG. 4 for inspection, a relatively small diameter (for example, a diameter of 200 m) is used.
It is possible to place an ingot of (m or less) on the holding table, but an ingot with a diameter of 300 mm or more cannot be lifted or moved directly by the worker due to its high weight, which is extremely dangerous. Accompanied by. Therefore, in order to handle a large-diameter ingot, a large-scale device such as a handling device for setting the ingot in the conventional notch inspection device is required.

On the other hand, as described above, there are five notch measurement items: depth, angle, tip R, symmetry, and surface roughness. In the notch measurement of the ingot, the projection method is not used because the ingot has a block shape. The wafer-like inspection sample can be obtained by the projection method, but the surface roughness (surface roughness) cannot be evaluated by the projection method. However, the surface roughness of this notch is becoming an important factor from the viewpoint of productivity, and it cannot be excluded from the measurement items.

Further, as described above, since the inspection of the notch shape at the ingot stage is an intermediate inspection, it is important that the work is as simple as possible. That is, it is preferable and strongly desired to measure the above five items including the surface roughness with one inspection device in terms of work efficiency.

The present invention has been made in view of the above problems, and avoids the complexity of handling due to the increase in diameter and weight of the ingot, the increase in risk, and the investment of new handling equipment. It is a main object of the present invention to provide a method and an inspection apparatus for accurately and simply evaluating the quality (depth, angle, tip R, symmetry, surface roughness) required for the notch shape.

[0011]

An invention relating to a method for inspecting a notch of a semiconductor wafer of the present invention is a method for inspecting a notch shape formed in a semiconductor wafer, wherein the wafer is held vertically, and a contact type shape is held. The notch shape is evaluated by using a measuring means (claim 1).

As described above, when the wafer is held vertically and the notch shape is evaluated using the contact type shape measuring means,
Conventionally, wafer-shaped inspection samples are generally evaluated by the projection method, and although surface roughness cannot be evaluated, even wafer-shaped inspection samples can be evaluated for surface roughness and other You can also evaluate quality items at the same time,
All of the notch shape quality items can be easily and accurately evaluated with one type of inspection device.

In this case, the wafer can be a slab cut out from an ingot (claim 2). Thus, instead of evaluating the notch shape as it is in the ingot, once a slightly thicker wafer (slab) is cut out from the ingot for inspection, and the notch shape of this slab is evaluated according to the present invention. It is not necessary to handle the ingot, and the burden on the inspection worker is reduced,
No handling device is required, and the notch inspection of a large diameter ingot can be performed easily and efficiently.

Further, in this case, the thickness of the wafer is 50
It can be 0 μm or more and 3 mm or less (claim 3). This is because when the thickness of the sample to be inspected is too thin, the stylus of the shape measuring means may come off from the outer periphery of the wafer when scanning the notch shape.
If it is too thick, it will be cut from the ingot and the loss will increase. In addition, it is much lighter than an ingot and is easier to handle, but if it is too thick, the weight of the wafer increases and it becomes difficult to handle. Therefore, it is preferable that the thickness is 500 μm or more and 3 mm or less.

The present invention relates to a semiconductor wafer notch inspecting apparatus for inspecting a notch shape formed on a wafer, and at least a holding means for vertically placing the wafer, a contact type shape measuring means, and the measuring means. Output means for outputting the notch shape obtained by the means (claim 4).

If the notch inspection device is constructed in this way,
The device can easily and accurately inspect the notch shape formed on the wafer, particularly the notch shape formed on the slab cut out from the ingot, and output the evaluation data. Therefore, there is no need to handle heavy ingots and the notch can be evaluated while the device remains small.

In this case, the holding means for vertically placing the wafer vertically holds the wafer by two holding plates, and one holding plate is fixed and the other holding plate is fixed. The movable means may be provided with a lock means (Claim 5). By doing so, the wafer can be held accurately and accurately in the vertical direction, so that the notch shape on the outer circumference of the wafer can be accurately scanned, and highly accurate analysis data can be obtained. Further, even wafers having different thicknesses can be handled, and the deviation of the shape measuring means with respect to the movement of the stylus can be reduced.

Further, in this case, the contact type shape measuring means is
It is desirable that the probe is a stylus type contour measuring device (claim 6). The stylus type contour profile measuring device is a device for measuring the coordinate fluctuations of the X axis and Z axis, and scans on the X axis side at a constant speed.
It is a device that evaluates changes in the Z-axis coordinates, and is a measuring device that can be easily handled and evaluated accurately.

Further, in this case, the notch shape output means is
It is desirable that the computer has a data analysis means (claim 7). Notch quality item is currently 5
There are items (depth, angle, tip R, symmetry, surface roughness), and if these are instantaneously analyzed, calculated, evaluated and output by a computer, it is extremely efficient and convenient.

The present invention will be described in detail below. The inventors of the present invention have required the quality required for the notch shape accurately and simply, avoiding the complexity of handling due to the increase in diameter and weight of the ingot, the increase in risk, the investment of new handling equipment, etc. In order to evaluate (depth, angle, tip R, symmetry, surface roughness, etc.), it was found that inspection should be performed in a wafer state, and various conditions were scrutinized to complete the present invention.

The notch inspection method of the present invention is a method for inspecting a notch shape formed on a semiconductor wafer, in which the wafer is held vertically and the notch shape is evaluated using a contact type shape measuring means. Is.

Conventionally, the notch of the wafer-shaped inspection sample is evaluated by the projection method, and the surface roughness cannot be evaluated by this method. On the other hand, like the present invention,
If the notch shape formed on the outer circumference of the wafer is evaluated by holding the wafer vertically and using the contact type shape measuring means, the surface roughness can be evaluated even with the wafer-shaped inspection sample, and other quality items can be evaluated. Can be evaluated at the same time. In this way, it becomes possible to easily and accurately evaluate all the notch quality of the wafer with one type of inspection device.

If the wafer used for the notch inspection is a slab cut out from the ingot, it is light in weight, so that it is not necessary to handle a heavy ingot as in the conventional case, and the burden on the inspection operator is reduced. A large ingot handling device is not required, and the notch inspection work can be easily and efficiently advanced. That is, the notch shape inspection of the ingot can be performed simply and efficiently by cutting out a slightly thick wafer (slab) from the ingot in which the notch is formed and using this slab.

In this case, the thickness of the wafer to be inspected is 50
It is preferable that the thickness is 0 μm or more and 3 mm or less. This is because when the thickness of the sample to be inspected is too thin, for example, less than 500 μm, the stylus of the shape measuring means may come off from the outer periphery of the wafer when scanning the notch shape. Normal,
Since the standard thickness of a silicon mirror-finished wafer having a diameter of 300 mm is around 0.8 mm, it can be said that it is sufficient to inspect the notch shape of a wafer having a thickness of 500 μm or more. On the other hand, if it exceeds 3 mm and is too thick, it leads to loss of crystals for cutting out from the ingot. Although it is much lighter and easier to handle than an ingot, if it is too thick, the weight of the wafer becomes heavy and the handling of the wafer becomes difficult. Therefore, if the thickness is 500 μm or more and 3 mm or less, a measurement error such as stylus derailment hardly occurs, and the sample can be easily handled.

The slab cut out for the notch inspection can also be used for inspection of items other than the notch inspection. For example, with respect to the crystal orientation, it is possible to efficiently inspect the slab after the notch measurement is directly turned to the X-ray measurement. This has the advantage that it is not necessary to handle a heavy crystal having a diameter of 300 mm even in X-ray measurement.

In addition, the oxygen concentration in the crystal, the resistivity, etc.
The characteristics due to crystals can also be inspected by using this slab and adding a little processing to it, and the loss of crystals due to the inspection can be suppressed as much as possible.

The wafer to be inspected is not limited to the disk shape, but may be divided into semicircular shapes for evaluation. The notch inspection apparatus of the present invention can evaluate even a semicircular wafer. In such a case, the remaining semi-circular wafer can be used for inspection of another inspection item, and various inspections of the wafer can be efficiently advanced.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. Here, FIG. 1 is an explanatory view showing an example of the notch inspection apparatus of the present invention.

The notch inspecting apparatus 1 of FIG. 1 is an apparatus for inspecting the shape of the notch 5 formed on the wafer W, and at least the holding means 7 for vertically placing the wafer and the contact type shape measuring means (stylus). It has a formula contour shape measuring machine 2) and an output means (computer 6) for outputting the notch shape obtained by the measuring means.

The holding means 7 for vertically placing the wafer W vertically clamps the wafer W between two holding plates, as shown in detail in FIG. 2, and fixes one of them. The fixed holding plate 8 and the movable holding plate 9 on the other side are provided with locking means, and the tightening wafer W is securely fixed vertically by the locking handle 10.
The fixed holding plate 8 is arranged parallel to the moving direction of the stylus 4 of the stylus contour measuring machine 2. Further, since the movable holding plate 9 can be locked at any position, wafers of various thicknesses can be held and evaluated.

By using the holding means 7 as described above, the wafer W can be held vertically and in conformity with the moving direction (scanning direction) of the stylus 4 of the stylus contour measuring machine 2, The stylus 4 does not drop off from the outer circumference of the wafer during the measurement. Further, on the surface of the holding plate which comes into contact with the wafer, it is desirable to attach a hard plastic plate such as a fluororesin to prevent contamination and damage to the wafer.

As the contact type shape measuring means, a stylus type contour shape measuring machine 2 is preferable, and a diamond stylus 4 scans the outer circumference of the wafer W and the contour of the notch 5 along the X axis at a constant speed, The X-axis and Z-axis coordinates are detected by the X-axis / Z-axis detector 3. The height of the X-axis / Z-axis detector 3 can be adjusted by the diameter of the wafer, and the relative position with respect to the wafer can also be adjusted. Fix after adjustment.

The notch shape output means is the computer 6 having the data analysis means, and sends the X-axis and Z-axis coordinate data detected by the X-axis / Z-axis detector 3 to the computer 6 and analyzes it. 5 items about notch 5 (depth,
The analysis data of angle, tip R, symmetry, surface roughness) is calculated, and the notch shape is output to a CRT or printer.

As the stylus type contour measuring device 2, for example, Contracer CBH-400 (trade name, manufactured by Mitutoyo Corporation) can be mentioned. This is a measuring instrument that is easy to handle and can evaluate contour shapes with high accuracy.

The notch inspection apparatus of the present invention constructed as described above is an apparatus for inspecting a notch shape formed on a wafer, particularly a slab sliced from an ingot, and is a notch formed on a conventional ingot. The notch formed in the wafer can be easily and efficiently evaluated, while it has an inspection capability that is almost equal to or higher than that of a device for inspecting the shape and is downsized.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples of the present invention, but the present invention is not limited thereto. (Example) A notch was inspected for a silicon single crystal ingot having a diameter of 300 mm. The ingot is manufactured by the Czochralski method, and the outer periphery of the pulled up single crystal ingot is cylindrically ground to make the diameter and the like uniform, and then a V-shaped notch is formed by grinding.

Slabs to be inspected were cut out to a thickness of 2 mm from both ends of the ingot. The notch in this slab is inspected by the inspection device as shown in FIG. First, the slab was held by the holding means as shown in FIG. 2 with the notch facing up.

The moving distance (X) is set by setting the stylus 4 of the stylus type contour measuring machine (the above-mentioned contour tracer CBH-400) on the outer circumference of the wafer and scanning it in the notch direction at 0.05 mm / sec. The unevenness (Z) with respect to is measured. The measurement result is processed by the computer and output.

Here, each inspection item is automatically calculated by a computer using analysis software based on the following definitions. The outer circumference of the wafer and the notch shape are finely scanned at a plurality of points to obtain notch shapes AL, C, and AR as shown in FIG. AL is the left shoulder of the notch, AR
Is the right shoulder of the notch, and C is the intersection of the notch and the perpendicular bisector of the straight line AL / AR. The raw data obtained so that AL and AR have the same height are subjected to coordinate conversion in advance.

Further, as DL, DL on the straight line AL ・ C
A point where C = 600 μm and a point where DR · C = 600 μm on the straight line AR · C are obtained as DR. Next, BL was determined as an intersection of a line passing through DL on a straight line of AL · C and an arc AL · C, and similarly as BR, an intersection of a line passing through DR and a line of passing AR on a straight line of AR · C. E is a virtual arc A
It was defined as the intersection of the perpendicular bisectors of the straight line AL and AR on L and AR.

The following five items were set as notch quality items. (1) The depth is the distance between the point E and the average value of the Z-axis values at a plurality of points on the left and right of the point C (for example, five points on each of the left and right sides). (2) The angles are vector AL / BL and vector AR / B
The angle formed by R. (3) The tip R is the radius of the least-squares approximation circle of the measurement point group of the arcs BL, C, and BR. (4) The symmetry is obtained by averaging the respective distances between the straight line AL / C and the left and right plural points (for example, left and right five points) of the point BL, and the right and left plural points of the straight line AR / C and the point BR (for example, left and right five points) Each)
The value obtained by subtracting the average value of each distance between and and the symmetry correction coefficient to correct the error of the device. (5) Surface roughness is surface roughness L (surface roughness on the L side), surface roughness R
(R-side surface roughness) is determined. Surface roughness L is straight line AL / BL
The least squares line is obtained from the measurement point group, and the distances between the respective maximum values of the upper and lower sides of the straight line and the least squares line are obtained, respectively, and the sum is shown. Similarly, the least-squares straight line is obtained from the measurement points of the straight line AR / BR, and the distances between the respective maximum values above and below the straight line and the least-squares straight line are obtained, and the surface roughness R is defined as the sum thereof.

As a result of evaluating the above five items, depth = 1.3
39 mm, angle = 92.030 deg, tip R = 0.9
30 mm, symmetry = 0.0078 mm, surface roughness L = 0.
All the items of 0122 mm and surface roughness R = 0.177 mm could be evaluated.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, has substantially the same configuration as the technical idea described in the scope of the claims of the present invention, and has any similar effect to the present invention. It is included in the technical scope of the invention.

For example, in the above embodiment, the diameter is 3
The case of inspecting a slab cut out from a 00 mm (12 inch) ingot has been described by way of example, but the present invention is not limited to this and can be applied to a wafer having a diameter of 4 to 16 inches or more. it can.

[0045]

As described in detail above, according to the notch inspection method and the notch inspection apparatus of the present invention, the notch of the ingot is inspected by inspecting the notch of the wafer without handling a heavy ingot. It becomes possible to perform notch inspection efficiently. Moreover, all notch shape characteristics including surface roughness can be evaluated simultaneously.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a notch inspection device of the present invention. (A) Front view, (b) Side view.

FIG. 2 is a diagram showing an example of a wafer holding means of the notch inspection device of the present invention. (A) Plan view, (b) Side view.

FIG. 3 is a diagram illustrating the definition of measurement items for notches.

FIG. 4 is an explanatory diagram showing an example of a conventional notch inspection device. (A) Front view, (b) Side view.

[Explanation of symbols]

1, 20 ... Notch inspection device, 2 ... Stylus type contour shape measuring device, 3 ... X-axis / Z-axis detector, 4 ... Stylus (stylus), 5 ... Notch, 6 ... Computer, 7 ... Wafer holding means, 8 ... Fixed holding plate, 9 ... Movable holding plate,
10 ... Lock handle, 11 ... V-shaped holding base, W
... Wafer (slab), G ... Ingot, R ... Notch tip approximate circle radius.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeharu Tsunoda             Odaira, Odakura, Saigo Village, Nishishirakawa-gun, Fukushima Prefecture             No. 150 Shin-Etsu Semiconductor Co., Ltd. Shirakawa factory F term (reference) 2F062 AA53 AA61 AA66 AA72 BB08                       BC28 BC80 CC09 CC25 CC26                       CC27 DD20 EE01 EE62 FF03                       FF25 FG07 GG90 HH05 HH14                       JJ01 JJ07 JJ08 JJ09 MM02                       MM08                 2F069 AA43 AA53 AA57 AA61 AA72                       BB15 BB40 CC07 DD25 DD27                       EE20 GG01 GG47 GG52 GG62                       HH04 HH30 JJ06 JJ25 LL03                       MM02 MM32 NN00 NN09 NN17                       NN26 PP02                 4M106 AA01 BA11 CA38 DB01 DJ02                       DJ20

Claims (7)

[Claims] 1. A method for inspecting a notch shape formed on a semiconductor wafer, wherein the notch shape is evaluated by holding the wafer vertically and using contact type shape measuring means. Method. 2. The notch inspection method according to claim 1, wherein the wafer is a slab cut out from an ingot. 3. The notch inspection method according to claim 1, wherein the thickness of the wafer is set to 500 μm or more and 3 mm or less. 4. An apparatus for inspecting a notch shape formed on a wafer, which outputs at least a holding means for vertically placing the wafer, a contact type shape measuring means, and a notch shape obtained by the measuring means. A notch inspection device having an output means. 5. A holding means for vertically placing the wafer vertically clamps the wafer with two holding plates, and one holding plate is a fixed type, and the other holding plate is a fixed type. The notch inspection device according to claim 4, wherein a locking means is provided as a movable type. 6. The notch inspection device according to claim 4 or 5, wherein the contact-type shape measuring means is a stylus-type contour shape measuring machine. 7. The notch inspection device according to claim 4, wherein the notch shape output means is a computer having a data analysis means.