JPH05160224A - Standard sample for inspecting surface of wafer - Google Patents

Abstract

PURPOSE:To prevent outflow of fine particles when contaminant of a stocking standard sample for inspecting a surface of a wafer is cleaned by securing the particles scattered on the wafer by covering it with a stationary film. CONSTITUTION:Fine particles 2 granulated from latex of polyethylene are scattered on an Si wafer 1 polished in a mirror surface. It is covered with a stationary film 3 by sputtering. The film 3 is desirably formed of the same material as that of the wafer 1 since the same cleanser can be applied in the case of cleaning. When cleaning resistance of a standard sample 10 in which the particles 2 are secured by the film 3 is evaluated, it is stably fixed after the particles 2 fixed on the wafer 1 are fed out by several % by an initial cleaning, and the sample which is stocked for a long period and contaminated can be cleaned. Accordingly, the sample for inspecting the surface of the wafer becomes durable against a long term stock and can be reused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer surface inspection standard sample, and more particularly to a wafer surface inspection standard sample which is capable of fixing fine particles scattered on a wafer, cleaning dirt and storing for a long period of time.

In recent years, the development of electronics has been remarkable, but the development largely depends on the innovation of the manufacturing technology of semiconductor devices. In a semiconductor device manufacturing process, a series of processes from a silicon wafer to a semiconductor element, a process called a so-called wafer process, various processes are repeated several times, and the wafer is held, moved, or transferred at various points in the process. Has been published. In particular, as the degree of integration of semiconductor elements increases, it is important how to keep the surface of the wafer clean in the steps such as fine patterning and vacuum processing such as sputtering. Therefore, inspecting the cleanliness of the wafer surface is one of the important manufacturing techniques.

[0003]

2. Description of the Related Art As the degree of integration of elements used in semiconductor devices increases and semiconductor devices with ultra-high integration such as 16 Mbits and 64 Mbits are developed, miniaturization in the manufacturing process of semiconductor elements The orientation is becoming more advanced. As a result, for example, a clean room in which a wafer process is performed is required to have high cleanliness (cleanness) such as class 1 or lower.

In order to maintain the cleanliness of the surface of the wafer even in such an atmosphere of high cleanliness, it is essential to measure and manage the amount of dust adhering to the surface of the wafer. ing. Therefore, a wafer surface inspection device is used.

2A and 2B are explanatory views of an example of a wafer surface inspection apparatus. FIG. 2A is a schematic configuration diagram, FIG. 2B is a clean surface, and FIG. This is the case for a surface that has been rusted. 3A and 3B are explanatory views of the standard sample, FIG. 3A is an enlarged cross-sectional view, and FIG. 3B is a case where a foreign substance is attached. In the figure, 1 is a wafer, 4 is a laser light source, 5 is a laser beam, 6 is a monitor, 7 is an XY stage, 8 is a foreign substance, 9 is a film-like product, 10 is a standard sample, and 20 is a wafer surface inspection apparatus. is there.

There are various methods for the wafer surface inspection apparatus 20, but the one exemplified here is one in which the surface of the wafer 1 is scanned with a beam of laser light 5 and the reflected laser light 5 is monitored. This is a method for evaluating the surface.

That is, in FIG. 2A, the laser light 5 emitted from the laser light source 4 is reflected on the surface of the wafer 1 and is incident on the monitor 6 including an image receiving element. Then, by mounting the wafer 1 on the XY stage 7 and moving the wafer 1 in the Y direction while scanning the laser light 5 in the X direction, for example, the entire surface of the wafer 1 can be licked by the laser light 5.

By the way, since the surface of the wafer 1 is mirror-polished, the laser beam 5 applied to the surface of the wafer 1 is totally reflected. Therefore, this totally reflected laser light 5
The monitor 6 receives the light by a so-called dark-field method in which the optical axis of is blocked. Then, as shown in FIG. 2B, in the case of a clean wafer 1 having no foreign matter 8 attached to its surface, the field of view of the monitor 6 is dark.

However, when the foreign matter 8 adheres to the surface of the wafer 1 as shown in FIG. 2C, the irradiated laser beam 5 is diffusely reflected by the foreign matter 8, so that the field of view of the monitor 6 is changed. It becomes bright.

Thus, the degree of adhesion of the foreign matter 8 is monitored by the monitor 6
The cleanness of the surface of the wafer 1 is inspected by evaluating the lightness and darkness displayed on the screen. Then, for the calibration of the wafer surface inspection apparatus 20 having such a configuration, the standard sample 10 made by intentionally adhering the foreign matter 8 whose geometrical characteristics are known to the surface of the wafer 1 is used.

In FIG. 3 (A), a standard sample 10 is obtained by scattering fine particles 2 of latex having a particle size of several μmφ obtained by emulsion polymerization of polyethylene, for example, on a wafer 1 serving as a substrate. The number of fine particles 2 scattered on the surface of the wafer 1 is several thousand to tens of thousands per wafer. Then, the standard sample 10 thus produced is stored for a long period of time and appropriately used for calibration of the wafer surface inspection apparatus.

[0012]

By the way, when the standard sample 10 for a wafer surface inspection apparatus is stored for a long period of time, bacteria and mold grow on the surface of the fine particles 2 and are deformed.
Further, as shown in FIG. 3B, foreign matter 8 such as dust adheres during storage, and a film-like product 9 composed of various organic and inorganic impurities contained in the atmosphere is naturally generated.

However, when attempting to wash in order to remove the foreign matter 8 and the film-like product 9, in the case of the conventional standard sample 10, most of the fine particles 2 attached to the surface together with the foreign matter 8 are present. Are washed away and gone. Therefore, conventionally, a troublesome work of preparing the standard sample 10 each time the wafer surface inspection apparatus 20 is calibrated has been required.

Therefore, the present invention provides a standard sample for wafer surface inspection, in which fine particles scattered on a wafer are covered and fixed with a fixing film so that the fine particles are not washed away even if stains during storage are washed. The purpose is to do.

[0015]

[Means for Solving the Problems]
Wafer and a wafer surface inspection configured such that the fine particles made of synthetic resin scattered on the wafer are covered with a fixing film on the wafer. It is solved by the standard sample for use.

[0016]

The conventional standard sample for inspecting the wafer surface cannot withstand cleaning because it is merely fine particles scattered on the wafer, but in the present invention, the fine particles are fixed by being covered with a sputtered fixing film.

In this way, even if it becomes dirty during long-term storage, it can be washed and thus can be used for calibration of the wafer surface inspection apparatus any number of times.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an enlarged sectional view of an essential part of an embodiment of the present invention,
Table 1 shows the results of evaluation of cleaning resistance of the samples according to the present invention.
In the figure, 1 is a wafer, 2 is fine particles, 3 is a fixed film,
10 is a standard sample.

In FIG. 1, a mirror-polished 6 inch φ
Approximately 24,000 fine particles 2 with an average particle size of 2.02 μmφ granulated from polyethylene latex on Si wafer 1
Scatter individually. Then, the film thickness is 100n by sputtering.
Cover with a fixed film 3 of about m.

The fixed film 3 is preferably made of the same material as that of the wafer 1, since the same cleaning liquid can be applied during cleaning. Therefore, a sputtered film of Si or SiO ₂ is applied.

Thus, in order to evaluate the washing resistance of the standard sample 10 having the fine particles 2 fixed on the fixing film 3, the conventional standard sample not covered with the fixing film 3 was used as a comparative sample to fix the fine particles 2 before and after washing. The rate, that is, the proportion of particles that are fixed on the wafer 1 and are not washed away even after cleaning is compared. As the cleaning condition, pure water is run for 24 hours, and then the number of fine particles 2 remaining on the wafer 1 is counted. The results are shown in Table 1.

[0022]

[Table 1]

As can be seen from Table 1, in the case of the conventional sample in which the fixing film 3 is not provided, 30,917 fine particles 2 scattered initially, 93% of the fine particles 2 flow out in the first washing. , The fixed rate is only 7%. Even in the second and subsequent cleanings, it remains almost constant within the measurement error range. That is, most of the fine particles 2 are washed away by one cleaning.

On the other hand, in the case of the sample according to the present invention, the initially scattered 24,006 fine particles 2 are washed out by only 2% in the first washing, and 98% of the fine particles 2 are fixed. .. Then, it can be seen that the particles 2 are almost constant within the range of the measurement error even after the second and subsequent washings, and the fine particles 2 are almost completely fixed.

The standard sample 10 produced in this way is the fixed film 3
2 is evenly deposited on the wafer 1 and the fine particles 2.
Since the reflected light is monitored by obliquely irradiating the light as shown in (A), the apparent particle diameter is monitored larger than the actual particle diameter of the fine particles 2. Therefore, by changing the thickness of the fixed film 3 in various ways, it is possible to prepare standard samples 10 having various particle sizes with the fine particles 2 having the same particle size.

Since the standard sample 10 according to the present invention can be cleaned and can be stored for a long period of time, the standard sample 10 having various grain sizes can be provided in the wafer surface inspection apparatus to automatically perform self-calibration. It is possible.

[0027]

EFFECTS OF THE INVENTION The standard sample for wafer surface inspection according to the present invention is stably fixed after the fine particles fixed on the wafer are washed away by several% in the first washing. Therefore, the standard sample can be reused if it is stored for a long period of time and washed when it becomes dirty.

Thus, in view of the situation where the cleanliness of the wafer surface is becoming more and more important in the wafer process in the manufacturing process of semiconductor devices, which is becoming more and more miniaturized, the present invention aims at improving the efficiency of the wafer process. It has a great contribution.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a main part of an embodiment of the present invention.

FIG. 2 is an explanatory view of an example of a wafer surface inspection device,
(A) is a schematic configuration diagram, (B) is a clean surface,
(C) is the case where the surface has foreign matter attached.

FIG. 3 is an explanatory view of a standard sample, (A) is an enlarged sectional view,
(B) is a case where a foreign substance is attached.

[Explanation of symbols]

 1 Wafer 2 Fine particles 3 Fixed film 10 Standard sample

Claims (2)

[Claims] 1. A Si wafer (1) and the wafer (1)
Having fine particles (2) made of synthetic resin scattered on the top surface of the wafer (1), the fine particles (2) are fixed on the wafer (1).
A standard sample for wafer surface inspection, which is covered by (3). 2. The fixing film (3) is made of Si or SIO _2.
The standard sample for inspecting a wafer surface according to claim 1, which is a sputtered film.