JPS62274633A - Surface inspection of wafer or substrate - Google Patents

Abstract

PURPOSE:To make it possible to detect foregin particles, which are attached on each chip, by taking a reference signal out of scattered light, which is generated from the wafer of a chip on a substrate, and comparing the signal of the scattered light generated from each chip with the reference signal. CONSTITUTION:Converged laser light from a laser light source 7 is controlled so that the focus is formed on a chip 6 of a wafer 5 through a condenser lens 8. The X-Y table of an X-Y air bearing stage 2 is moved. Thus the entire surface of the chip 6 is scanned. Scattered light is converged with optical guide members, which are arranged in a plurality of numbers so as to surround the light around the condenser lens 8. Photolectric conversion is performed with a photomultiplier tube 10. The intensity of the scattered light undergoes analog to digital (A/D) conversion at 10 bits with a signal processing system 11. The result is stored in a first image information memory part 13 through an image information processing computer 12. Thus the pseudo-design data to the nth number, which are stored in the first image information memory part 13, are made to be the correct design data. From the (n+1)th number and thereafter, it is judged that the difference signal indicates a foreign particle. The place of the signal is displayed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a wafer surface on which a plurality of chips of the same shape are formed, or a substrate on which a plurality of chips of the same shape are provided. The present invention relates to a technique for inspecting foreign particles on a surface, and particularly to a technique effective for inspecting foreign particles without being influenced by patterns such as grooves and holes formed in a manufacturing process.

[Prior art]

The development of manufacturing technology for forming fine patterns for semiconductor devices and the like has been remarkable in recent years, and the search for technologies for increasing the density and integration of fine patterns is progressing. In order to achieve this high density and high integration, technology for removing dust and the like using super clean rooms and the like is becoming increasingly important. Since foreign particles such as dust adhere to the wafer surface and cause defects, they must be constantly inspected and controlled throughout each manufacturing process in semiconductor device manufacturing.

Foreign matter management in the conventional semiconductor device manufacturing process involves leaving a mirror-finish wafer in the required location for a certain period of time.
This is done by irradiating light onto the foreign particles adhering to the surface, and receiving and reading the scattered light scattered by the foreign particles.

Furthermore, for foreign particles of 1 μm or more and defect patterns, research is underway into visual inspection using a microscope and automated pattern inspection. (Hatahiko Hara et al., Transactions of the Institute of Electronics and Communication Engineers, V
ol, J 69- Ct' No, 4, P,
385° Also, in order to inspect foreign particles that adhere during each manufacturing process, a part of the wafer is prepared without processing such as grooves or holes, and after each manufacturing process is completed, this part is inspected for foreign particles, and the wafer is inspected for foreign particles. The method used was to estimate the total number of foreign particles.

[Problem that the invention seeks to solve]

However, in the former conventional wafer surface inspection method of reading the pattern on the wafer surface by detecting scattered light, the wafer surface needs to be in a mirror-like state, and once the wafer has passed through a process, it has not been processed to form grooves or holes on the surface. The received wafer is
When foreign particles or defect patterns are smaller than 1 μm, there is a problem that the foreign particles cannot be measured except by examining the surface condition using an electron microscope or the like.

Furthermore, in conventional wafer surface inspection methods such as the latter,
It has not been possible to directly inspect the contamination state of the wafer surface due to foreign particles during the actual manufacturing process.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the wafer surface without being affected by patterns such as grooves and holes machined on the wafer in the semiconductor device manufacturing process. An object of the present invention is to provide a technology that can inspect foreign particles attached to a surface.

The above and other objects and novel features of the present invention will be explained by the following description of the specification and the accompanying drawings.

[Means for solving problems]

A brief overview of one typical invention disclosed in this application is as follows.

In other words, in a semiconductor manufacturing process or a manufacturing process that simultaneously manufactures objects of the same shape, light is irradiated onto patterns of grooves and holes processed into chips on the surface of a wafer or substrate, and foreign particles attached during the manufacturing process. A wafer or substrate surface inspection method for detecting foreign particles from scattered light generated by a plurality of chips, the method comprising: extracting a reference signal from scattered light generated from each of a plurality of chips on the wafer or substrate; The present invention is characterized by comprising a process of comparing signals of scattered light generated from the chips, and a process of detecting foreign particles attached to each chip from the comparison results.

[Effect]

According to the means, a reference signal is extracted from the scattered light generated from each chip on the wafer or substrate, the reference signal and the signal of the scattered light generated from each chip are compared, and from the comparison result, the signal on each chip is extracted. Detect foreign particles attached to each.

For example, by irradiating light onto one or more chips on a wafer, reading the pattern generated by scattering, and storing the pattern in a storage unit of an image information processing computer,
The pseudo design data is used as pseudo design data, and the operation of comparing this pseudo design data with chips at different locations is repeated, the pseudo design data is gradually approximated to the design data with high accuracy, and finally, this approximate data is compared with each chip. By detecting foreign particles on a chip, it is possible to inspect foreign particles on a chip processed in a manufacturing process, which could not be detected using conventional techniques.

[Embodiments of the invention]

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

In addition, in all the times for explaining the example.

Components having the same function are given the same reference numerals, and repeated explanations thereof will be omitted.

Embodiment I FIG. 1 is a block diagram showing a schematic configuration of an apparatus for explaining a wafer or substrate surface inspection method according to an embodiment of the present invention.

In FIG. 1, 1 is a support such as a surface plate, and 2 is an X-Y air bearing stage, and this X-Y air bearing stage 2 is movably supported by the support 1. 3 is X-Y
4 is the X-axis drive motor of the air bearing stage 2, and 4 is the Y-axis drive motor of the air bearing stage 2.
It is a shaft drive motor.

5 is a wafer made of a semiconductor, and 6 is a chip formed on the wafer 5 and processed into the same shape. 7 is a laser light source such as helium neon (Hs-Ne); 8
is a condensing lens for condensing the laser light emitted from the laser light source 7 onto the wafer 5 or chip 6 . 9 is a light guide member that guides the scattered light generated by the wafer 5 or chip 6; 10 is a photomultiplier tube that converts the light into an electrical signal; and 11 is a signal processing system that performs analog-to-digital (A/D) conversion. , 12 is an image information processing computer;
13.13' is the first. This is a second image information storage section.

Next, the wafer surface inspection method of Example 2 will be explained with reference to FIG.

In FIG. 1, a condensed laser beam from a laser light source 7 is controlled to be focused on a chip 6 of a wafer 5 by a condensing lens 8, and the X-Y table of the X-Y air bearing stage 2 is moved. The entire surface of the chip 6 is scanned.

Here, the scanning pitch of the laser beam is set to be equal to or less than the spot diameter, and overlapping scanning is performed.

The scattered light is collected by a plurality of light guide members 9 arranged around a condensing lens 8, subjected to photoelectric conversion by a photomultiplier tube 10, and further reduced to 1o by a signal processing system 11.
The data is analog-to-digital (A/D) converted in bits and stored in the first image information storage section 13 via the image information processing computer 12.

Next, the wafer is moved by the XY air bearing stage 2 so that the laser beam is focused on the nearby chip 6, and the same operation as the wafer surface inspection operation performed previously is performed. The digital signal obtained by this operation and the signal stored in the first image information storage section 13 are compared and calculated by the image information processing computer 12, and only the same signals are stored in the first image information storage section 13, The difference signal is stored in another second image information storage section 13'. Furthermore, the third, fourth, etc.
...The same signal processing is performed for the n-th chip 6, and the difference signal is compared with the second image information storage unit 13'. If there are two or more identical signals, this same signal is used as the design data. The image information is stored in the first image information storage section 13.

In this way, the pseudo design data up to the n-th stored in the first image information storage unit 13 are set as correct design data,
From the (n+1)th difference signal, it is determined that the difference signal is a foreign particle, and the location thereof is displayed.

Finally, measurements are repeated again for the first to nth chips 6.

In this way, the distribution state of foreign particles is inspected for the entire wafer.

As is clear from this result, the feature that the chips 6 on the wafer 5 are processed with the same dimensions can be effectively utilized.
Processed chips that were previously impossible to measure6
can be inspected for foreign particles on the top.

[Example ■] FIG. 2 is for explaining embodiment (2) of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an implementation device.

In FIG. 2, 14 is a diffraction grating that diffracts the laser light source 7.

As shown in FIG. 2, in the wafer surface inspection method of this embodiment (2), the laser light from the laser light source 7 is transmitted through the diffraction grating 14 to the ±0th order, ±1st order, ±2nd order...±n This becomes the next diffracted light. These diffracted lights are made into parallel light by a condensing lens 8 having a focal length f, which is disposed at a distance f, and are focused on each chip 6 located at a distance f from the condensing lens 8.

Further, the optical system is adjusted to match the spacing between each chip 6. The scattered light from each chip 6 is input into a photomultiplier tube (not shown) by a plurality of light guide members 9, and is converted into an electrical signal there.

This electrical signal is converted into an analog/digital (A/D) signal by a signal processing system 11 and converted into an image information processing computer 1.
In step 2, each diffracted light beam is subjected to signal processing at the same time. When there are two or more identical signals, this is used as design data, and the difference signal is recognized as a foreign particle.

With such a configuration, a plurality of chips 6 can be processed in parallel, and inspection time can be reduced.

In addition, regarding the intensity difference of the laser beam depending on the diffraction order, it is necessary to electrically adjust the zero level on the unprocessed wafer.

The present invention has been specifically explained above using examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

For example, in the embodiment, as means for obtaining the reference signal,
Although means for comparing the signals of the scattered lights generated from the chips 6 on the wafer 5 was used, means for averaging (calculating) the respective scattered lights may also be used.

The present invention can also be applied to the case of inspecting fine particles attached to a plurality of chips of the same shape arranged on a substrate.

〔Effect of the invention〕

As described above, according to the present invention, a reference signal is extracted from the scattered light generated from each chip on a wafer or a substrate, and the reference signal and the signal of the scattered light generated from each chip are compared. By means of detecting foreign particles attached to each chip from the comparison results, it is possible to inspect foreign particles on the surface of the chip where grooves or holes are formed, which was previously impossible. Moreover, the contamination state after each manufacturing process can be inspected.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an implementation apparatus for explaining a wafer surface inspection method according to Embodiment I of the present invention, and FIG. 2 is a block diagram for explaining Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a schematic configuration of an implementation device. In the figure, 1... Support stand, 2... Air bearing X-Y stage, 3... X-axis drive motor, 4... Y-axis drive motor, 5... Wafer, 6... Chip , 7... Laser light source, 8... Condensing lens, 9... Light guide member, 10
...Photomultiplier tube, 11...Signal processing system, 12...
- Image information processing computer, 13.13'... 1st. Second image information storage unit, 14... is a diffraction grating.

Claims (3)

[Claims] (1) In a semiconductor manufacturing process or a manufacturing process that simultaneously manufactures objects of the same shape, light is irradiated onto patterns of grooves and holes machined in chips on the surface of a wafer or substrate and foreign particles attached during the manufacturing process. A wafer or surface inspection method for detecting foreign particles from scattered light generated by irradiation, the process comprising: extracting a reference signal from scattered light generated from each of a plurality of chips on the wafer or substrate;
A wafer or substrate surface inspection method comprising the steps of comparing the reference signal with a signal of scattered light generated from each chip, and detecting foreign particles attached to each chip from the comparison result. . (2) The process of extracting the reference signal consists of a process of comparing signals of scattered light generated from each chip on the wafer, and a process of extracting only the same signals from the comparison results by averaging processing. A wafer or substrate surface inspection method according to claim 1, characterized in that: (3) The wafer or substrate surface inspection method according to claim 1 or 2, wherein the light is a single beam or a plurality of parallel beams.