JPH01219546A - Foreign matter inspecting method for surface of semiconductor wafer - Google Patents

Abstract

PURPOSE:To detect even foreign matter which is smaller than a detection limit with high sensitivity by depositing or growing a thin film which reflects laser light by its surface on the surface of the semiconductor wafer to be inspected before the foreign matter is inspected. CONSTITUTION:The thin film 8 which reflects the laser light by its surface is deposited or grown on the surface of the semiconductor wafer 1 to be inspected before the foreign matter is inspected. If the foreign matter 2 sticks on the surface of this wafer 1, the size of the foreign matter 2 can be increased exceeding the detection limit apparently by an expansion part 8a corresponding to the covering part of the foreign matter 2 by the thin film 8 which is deposited or grown including the foreign matter 2. Consequently, the quantity of the laser light 3 projected on the foreign matter 2 substantially, i.e. reflected light 4 which is reflected and scattered by the foreign matter 2 can be increased. Consequently, even if the foreign matter 2 is smaller in size than the detection limit, it can be detected.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for inspecting foreign matter on the surface of a semiconductor wafer.
More specifically, the present invention relates to an improvement in an inspection method for detecting foreign matter attached to the surface of a semiconductor square as an object to be inspected in the manufacturing process of a semiconductor device.

[Conventional technology]

A conventional method of inspecting the surface of a semiconductor wafer for foreign matter is shown in FIG.

That is, in the conventional method shown in FIG. 3, reference numeral 1 denotes a semiconductor wafer to be inspected, and numeral 2 denotes a foreign substance attached to the surface, so-called main surface, of the semiconductor wafer 1 to be inspected.

Further, 3 indicates a laser beam irradiated onto the surface of the semiconductor wafer l to be inspected in order to detect the foreign substance 2, 4 indicates the reflected light of the laser beam 3 that is irradiated to the foreign substance 2 and reflected and scattered, Further, 5 is the semiconductor wafer 1 to be inspected.
A light receiving section is placed at a predetermined position above and collects and detects a part of the reflected light 4; 6 is a photoelectric conversion section that converts the optical signal from the light receiving section 5 into an electrical signal; This is an inspection stage on which a semiconductor wafer 1 to be inspected is placed and rotated to scan the surface of the wafer 1 with the laser beam 3.

However, in this conventional method, the surface of the semiconductor wafer l to be inspected is irradiated with the laser beam 3 from a specific direction, and the surface is irradiated with the laser beam 3 while rotating the inspection stage 7 at a predetermined speed. By sequentially scanning in the direction, if there is any foreign object 2 on the same surface, the laser beam 3 is reflected and scattered by this foreign object 2 to produce reflected light 4, and the rotation scanning Accordingly, a part of the reflected light 4 is sequentially focused on a light receiving section 5 disposed at a predetermined position on the upper part, and this is converted into an optical signal by the light receiving section and sent to a converting section 6 manually. The input optical signal is converted into an electrical signal, and the size of the foreign matter 2 attached to the surface of the semiconductor wafer l to be inspected can be determined based on the detection voltage level and the number of times in the converted electrical signal. The number can be easily detected.

[Problem to be solved by the invention]

However, in the conventional method performed as described above, when the foreign matter 2 attached to the surface of the semiconductor wafer 1 to be inspected reaches a certain size, that is, smaller than the detection limit size, the foreign matter 2 becomes smaller than the detection limit. In proportion to the size
As the intensity of the laser beam 3 that irradiates this decreases, the reflected light 4 that is scattered by the foreign object 2 becomes too small to be detected. As the technology progresses, in such conventional methods, the detection sensitivity for foreign matter 2 generally becomes lower, and therefore, effective and practical foreign matter detection cannot be achieved.

This invention was made in order to solve these conventional problems, and its purpose is to detect when foreign matter attached to the surface of a semiconductor wafer to be inspected is smaller than the detection limit. This makes it possible to detect this with high sensitivity even when it is present.

An object of the present invention is to provide a method of inspecting foreign matter on the surface of a semiconductor wafer of this type.

[Means to solve the problem]

In order to achieve the above object, the method for inspecting foreign matter on the surface of a semiconductor wafer according to the present invention includes depositing a thin film capable of surface-reflecting laser light on the surface of the semiconductor wafer to be inspected, on the inspection surface of the foreign matter. Or, it is made to grow and form.

That is, the present invention irradiates and scans the surface of a semiconductor wafer to be inspected with a laser beam, and when foreign matter is attached to the surface, receives reflected light that is scattered by the foreign matter. In a foreign matter inspection method capable of detecting the presence of foreign matter, a thin film capable of surface reflection of laser light is deposited or grown on the surface of the semiconductor wafer to be inspected before the foreign matter is inspected. This is a method for inspecting foreign matter on the surface of a semiconductor wafer.

(Function) Therefore, in the method of the present invention, before inspecting for foreign matter, a thin film that can reflect laser light on the surface is deposited on the surface of the semiconductor wafer to be inspected.

If a foreign substance is attached to the surface of the semiconductor wafer to be inspected by growth or formation, the expansion portion corresponding to the part covered with the foreign substance in the thin film that is deposited or grown and containing the foreign substance, The same foreign object,
Despite its apparent appearance, it can grow larger than the detection limit, and as a result, the amount of laser light that is irradiated to the foreign object to be detected, and even the amount of light reflected and scattered by the foreign object. As a result, it is possible to detect foreign particles attached to the surface of the semiconductor to be inspected even if the size is below the detection limit. .

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for inspecting foreign matter on the surface of a semiconductor wafer according to the present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 is a partial cross-sectional configuration diagram schematically showing an outline of a foreign matter inspection apparatus on the surface of a semiconductor wafer to which this embodiment method is applied. The same reference numerals indicate the same or equivalent parts.

That is, also in the configuration of the embodiment shown in FIG. 1, the reference numeral 1 indicates the semiconductor wafer to be inspected, 2 indicates the foreign matter attached to the surface of the semiconductor wafer 1 to be inspected, and 8 indicates the foreign matter 2. The thin film 8a, which is deposited or grown on the surface of the semiconductor wafer to be inspected and is capable of reflecting the laser beam, is formed by depositing or growing the thin film 8, so that the thin film 8a corresponds to the part covered with foreign matter. , foreign object 2
The appearance is a bulge of a thin film that has grown into a large size.

Further, 3 is a laser beam irradiated onto the surface of the semiconductor wafer l to be inspected, in this case, the surface of the thin film 8, in order to detect the foreign material 2, and 4 is a portion corresponding to the covering of the foreign material 2. The figure shows the reflected light of the laser beam 3 that is irradiated onto the bulging portion 8a of the thin film and is reflected and scattered.Furthermore, 5 is placed at a predetermined position in the F direction of the semiconductor wafer 1 to be inspected, and part of this reflected light 4 is shown. 6 is a photoelectric conversion unit that converts the optical signal from the light receiving unit 5 into an electrical signal;
Reference numeral 7 denotes an inspection stage on which the semiconductor wafer 1 to be inspected is placed and rotated to scan the surface thereof with the laser beam 3.

Therefore, in this embodiment method, the thin film 8 covering the surface of the semiconductor wafer 1 to be inspected containing the foreign matter 2 is irradiated with the laser beam 3 from a specific direction, and the inspection stage 7 is moved to a predetermined position. By sequentially scanning the thin film 8 in one direction while rotating at a high speed, it is found that some foreign matter 2 is present on the surface of the semiconductor wafer l to be inspected, and the thin film 8 is removed due to this foreign matter 2. If a bulging part 8a is formed in the corresponding part on 8, even if the size of the foreign object 2 is below the detection limit, the appearance will be good and the size will become larger than the detection limit. The laser beam 3 to be irradiated is reflected and scattered by this bulging portion 8a to generate reflected light 4. Thereafter, as in the case of the conventional method described above, along with the rotational scanning, A part of the reflected light 4 is placed at a predetermined position on the upper part of the light receiving part 5
The light is sequentially focused on the light receiving section, which inputs it as an optical signal to the photoelectric conversion section 6.The conversion section 6 converts the input optical signal into an electrical signal, and detects the converted electrical signal. The size and number of foreign particles 2 attached to the surface of the semiconductor wafer 1 to be inspected can be easily detected by the voltage level and the number of times.

Next, an example will be given of the deposition or growth of the thin film 8 which is coated on the surface of the semiconductor wafer 1 to be inspected and is capable of reflecting laser light on the surface.

The following table shows the materials attached to the surface of the semiconductor wafer 1 to be inspected. A separate thin film 8 that can reflect laser light on the surface of the foreign object 2 having a size of about 10 μm is formed using polystyrene.
i, WSi, BPSG,) ITO (high temperature oxide film) was grown to a thickness of roooA.

The growth rate of foreign matter 2 due to each of these thin films 8 is shown.

In this S, the growth rate is expressed as "(foreign particle diameter before thin film formation)/(foreign particle diameter after thin film formation)".

In this case, the reason why the growth rate of the thin film using polysi is especially high is that this polysi
This is because when Si is formed on a foreign object, the same portion grows abnormally into a protrusion shape, and the film thickness around the foreign object becomes thicker than the film thickness on the substrate surface.

In addition, in the above-mentioned example method, the size of the attached foreign matter was described as 10 μm, but the size of the attached foreign matter was 0.5 μm.
It can be applied to microscopic objects of μl or less, and poly
In addition to si JSi, BPSG, HTO, e.g.
Of course, MoSi, TiN, A11, etc. can be used.

〔Effect of the invention〕

As detailed above, according to the method of the present invention, the surface of the semiconductor wafer to be inspected is irradiated and scanned with a laser beam, and when foreign matter is attached to the surface, the foreign matter is detected. In a foreign object inspection method that detects the presence of the same foreign object by receiving scattered reflected light, before inspecting the foreign object, a laser beam is applied to the surface of the semiconductor chip to be inspected in advance. Since a reflective thin film is deposited or grown, if foreign matter is attached to the surface of the semiconductor wafer to be inspected, the thin film deposited or grown containing this foreign matter will not be affected by the foreign matter. The expanded portion corresponding to the covered portion allows the same foreign object to take on a form that has a larger appearance than the detection limit, and thereby allows the foreign object to be detected to become larger than the detection limit. It is possible to substantially increase the amount of laser light irradiated and the reflected light that is reflected and scattered by foreign objects, and as a result, even if the surface of the semiconductor wafer to be inspected is Even if the size of the attached foreign matter is below the detection limit, it can be detected. Moreover, in the manufacturing process, it is possible to detect foreign matter even if it is on the surface of the semiconductor wafer subject to single-wave inspection. If so, this method has excellent features such as being easy to implement and requiring only the addition of a very simple means of coating with a thin film that contains the foreign matter and can reflect the laser beam on its surface.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional configuration diagram schematically showing an overview of an embodiment of the method for inspecting foreign substances on the surface of a semiconductor wafer according to the present invention, and FIG. FIG. 3 is a partial cross-sectional configuration diagram schematically showing an outline of a conventional foreign object inspection method according to the above example. l... Semiconductor wafer to be inspected, 2... Foreign matter on the semiconductor wafer, 3... Laser light, 4... Reflected light, 5... Light receiving section, 6...・Photoelectric conversion section, 7・
...Inspection stage, 8...Thin film whose surface can reflect laser light, 8a...Bulging portion of thin film. Agent Masuo Oiwa No. 2, No. 3

Claims (1)

[Claims] The surface of the semiconductor wafer to be inspected is irradiated and scanned with a laser beam, and if a foreign object is found on the surface, the reflected light scattered by the foreign object is received and the foreign object is detected. A foreign matter inspection method capable of detecting the presence of foreign matter, characterized in that, before inspecting the foreign matter, a thin film capable of surface reflection of laser light is deposited or grown on the surface of the semiconductor wafer to be inspected. A method for inspecting foreign matter on the surface of a semiconductor wafer.