JPS61279131A - Defect removing device for semiconductor wafer - Google Patents

Abstract

PURPOSE:To improve the processing capacity for removing foreign matter remarkably by utilizing laser beams for detecting and removing any foreign matter on the surface of a semiconductor wafer. CONSTITUTION:A semiconductor wafer 11 is set on a stage to be shifted in XY direction. The wafer 11 is scanned by the first laser beam source 13 being actuated. The laser beams 14 may be scattered by any existing foreign matter 12 while the scattered beams 15 are monitored by a detector 16 to detect the foreign matter 12 in terms of the fluctuation intensity of scattered beams 15. The stage is temporarily stopped at the position wherein the foreign matter 12 is detected and then the foreign matter 12 is further irradiated with the other high output laser beams 17 emitted from the second laser beam source 18. The foreign matter 12 on the wafer 11 is melted and evaporated by the laser beams 17 to be removed for flattening the wafer surface 11. Through these procedures, the processing capacity for removing foreign matter 12 can be improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for removing defects from semiconductor wafers, and is particularly used for removing foreign matter from the surface of semiconductor wafers generated during vapor phase growth.

[Technical background of invention]

In the vapor phase growth process of semiconductor wafers (semiconductor substrates), for example, in the epitaxial growth of silicon on a silicon single crystal substrate, reaction products and fine particles that adhere to the inside of the vapor phase growth apparatus fall onto the surface of the growth layer and form mounds. Surface defects (foreign objects) called . Since this mound is generally protruding from the semiconductor surface, it may damage the mask during the subsequent PEP process, especially in the case of contact exposure (significantly shortening the life of the mask). The protruding foreign matter must be detected and removed by some method.

Conventionally, the above-mentioned foreign matter has been detected by visual inspection, by optical microscopic observation, or recently by using scattered light emitted by laser light. On the other hand, the removal of the foreign matter is performed by first determining the presence or absence of the foreign matter by some method, selecting semiconductor wafers containing the foreign matter, and then using a completely different foreign matter removal device. For example, as a device for removing protruding foreign matter, the device shown in FIG. 2 is known. 1 in the figure is a support stand that supports the semiconductor wafer 2. As shown in FIG. A flat plate 4 made of sapphire or the like is provided on the support base 1 to crush the protruding foreign matter 3 on the surface of the semiconductor wafer 2 .

[Problems with background technology]

However, according to the conventional technology, inspection, sorting, and
Since the removal process is performed in different devices, loading and unloading and transferring wafers from each device becomes complicated, leading to a decrease in throughput. Furthermore, since the removing device shown in Fig. 2 employs a method of mechanically crushing the protruding foreign matter, a large stress is applied to the wafer 2 itself, and depending on the size of the foreign matter, the wafer 2 may crack or may not necessarily be flat. There is a problem of No. 4 in which the surface of the wafer 2 is damaged by fragments of foreign matter that are not completely oxidized or crushed.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and it greatly increases the processing capacity for removing foreign matter compared to the conventional method, and also reduces secondary contamination caused by cracks in semiconductor wafers and fragments of foreign matter. It is an object of the present invention to provide a semiconductor wafer defect removal device that can avoid adverse effects.

[Summary of the invention]

The present invention aims to achieve the above object by using a laser to detect and remove foreign matter on the surface of a semiconductor wafer. Specifically, the present invention includes a stage for setting a semiconductor wafer;
a first laser light source that detects foreign matter on the semiconductor wafer;
The apparatus is characterized in that it includes a detector that detects scattered light reflected by the foreign object, and a second laser light source for removing the foreign object that is synchronized with the first laser light source.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 11 in the figure indicates a semiconductor device, which is set on a stage (not shown) that is movable in the X and Y directions. In addition,
Reference numeral 12 indicates a protruding foreign substance attached to the semiconductor wafer 11. Above the stage, a first laser light source 13 with good light convergence for detecting the foreign object 12 is fixedly installed. This laser light source 13 is made of, for example, He-Ne.

After the tj4 & laser light 14 is emitted from the laser light source 13, it is scattered by the foreign object 12. A detector 16 for detecting scattered light 15 scattered by the foreign object 12 is provided above the stage. This detector 16 measures the position and size of the foreign object 12. Further, above the stage, the foreign matter 12 is exposed to a strong laser beam 17.
A second laser light source (for example, a YAG laser) 18 with good light focusing ability is fixedly installed to melt and evaporate the material.

The light sources 13 and 18 mentioned above are synchronized with each other and aligned so that they intersect accurately on the semiconductor wafer 11.

In a defect removing apparatus having such a structure, a semiconductor wafer 1
Detection and removal of the foreign matter 12 on the inside of the vacuum container) is carried out as follows. First, the semiconductor wafer 11 is placed on a stage movable in the X and Y directions.

Here, the semiconductor wafer 11 which has been soldered 1 to 1 is scanned with the first laser light source 13 turned on. The laser beam 13 is scattered where the foreign object 12 is present, and this scattered light 15 is monitored by a detector 16 to detect the foreign object 12 as a change in the intensity of the scattered light. The stage temporarily stops at the position where the foreign object 12 is detected, and the second laser light source 1
A high-power laser beam 17 is irradiated from 8. Then, the laser beam 17 melts and evaporates the foreign matter 12 on the semiconductor chip 1, thereby removing or flattening it. Here, in order to check whether the foreign matter 12 has been completely removed, the second laser light source is turned off, and the scattered light 1 from the foreign matter 12 is
5 may be measured again by the detector 16. Further, if the foreign matter 12 cannot be removed by one irradiation of the laser beam 17, the above method may be repeated. Note that once one foreign object is removed, the stage starts moving again and scans to the position where the next foreign object is detected. In this way, foreign matter is detected and removed over the entire surface of the semiconductor wafer, and the process is completed.

According to the present invention, the following effects are achieved.

(2) Since the first and second laser light sources 13 and 18 are synchronized with the detection and removal of the foreign matter 12 on the semiconductor wafer 11, respectively, detection and removal can be performed continuously within the same device. The removal capacity can be greatly increased.

■First laser light source 1 with good light focusing ability for removing foreign matter 12
8, it is possible to selectively dissolve and remove only foreign substances. In addition, by interlocking with the first laser light source 13, it is possible to precisely remove foreign substances without over-melting or unmelting.

(2) Since foreign matter is removed in a vacuum device, it is possible to cleanly remove the foreign matter without contaminating the semiconductor wafer 12.

(2) Since foreign objects are not mechanically crushed as in the conventional method, secondary contamination such as cracks and scratches on the semiconductor wafer 11 can be avoided.

Note that in the above embodiment, the stage moves in the XY direction,
Although the case has been described in which the first and second laser light sources are each fixedly installed, the present invention is not limited to this, and the stage may be fixed and the first and second laser light sources may each move in the X and Y directions.

Further, in the above embodiment, the first laser light source is )(e-J
Although the case where the second laser light source is a YAG laser has been described, the present invention is not limited thereto.

〔Effect of the invention〕

As detailed above, according to the present invention, there is provided a highly reliable semiconductor wafer defect removal device that can efficiently remove foreign matter on a semiconductor wafer without causing secondary contamination such as cracks or scratches on the semiconductor wafer itself. can be provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a semiconductor wafer defect removal apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional defect removal apparatus. 11... Semiconductor wafer, 12... Foreign matter, 13.18
...Laser light source, 14.17...Laser light, 15.
...scattered light, 16...detector.

Claims (3)

[Claims] (1) A stage for setting a semiconductor wafer, a first laser light source for detecting foreign matter on the wafer, a detector for detecting scattered light reflected by the foreign matter, and the foreign matter synchronized with the first laser light source. A semiconductor wafer defect removal apparatus comprising: a second laser light source for removing defects. (2) The semiconductor wafer defect removal apparatus according to claim 1, wherein the removal of foreign substances on the semiconductor wafer is performed in a vacuum container. (3) The stage is moved in the XY direction, and the first and second
2. The semiconductor wafer defect removal apparatus according to claim 1, wherein the laser light source is fixed.