JPH07159333A - Apparatus and method for inspection of appearance - Google Patents

Abstract

PURPOSE:To provide an appearance inspection apparatus which detects a pattern defect caused on the surface of an object to be inspected and which analyzes also an occurrence cause on the basis of a detected result. CONSTITUTION:The appearance inspection apparatus is provided with a light source 13 which irradiates a semiconductor wafer 1 mounted on a sample stand 12 with beams of light, a reflected-light detector 14 which detects its reflected light and which outputs a signal indicating the feature of a pattern defect, an appearance-inspection control device 15 in which values of many parameter signals obtained by the pattern-defect detection means are divided into groups according to the occurrence cause of the pattern defect and with a storage device 16 which stores the grouped pattern defect. The control device 15 recognizes the pattern defect by the signal from the detector 14, it compares the pattern defect with data stored in the storage device 16, and it judges the occurrence cause of the defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique which is particularly effective when applied to a visual inspection apparatus and further to a semiconductor wafer visual inspection apparatus. For example, the cause of pattern defects such as foreign matter adhering to the wafer surface and pattern defects Related to useful technology for analysis.

[0002]

2. Description of the Related Art In manufacturing a semiconductor device, in order to increase the manufacturing yield, a foreign material inspection of a wafer surface which causes a pattern abnormality such as a disconnection / short circuit of a pattern is performed every time a main manufacturing process is completed. This foreign matter inspection is performed using the appearance inspection device, for example, in the following procedure. First,
A specific chip surface of a semiconductor wafer as an object to be inspected is irradiated with light for inspecting foreign matter, and the brightness of the reflected light is detected by a reflected light detector (for example, a CCD image pickup device). Then, one or two or more chips adjacent to this chip are similarly irradiated with inspection light to detect the brightness of the reflected light. And
Signals (brightness signals) representing the brightness of the respective reflected lights reflected from the same pattern of the two chips are compared with each other to obtain an inspection signal (parameter signal) representing a difference in the brightness. Then, based on this parameter signal, it is determined whether or not defects such as foreign matter and pattern defects have occurred on the wafer.

[0003]

However, the present inventors have clarified that the above-mentioned technique has the following problems. That is, the above-mentioned conventional semiconductor wafer appearance inspection apparatus,
Regarding the pattern defect, only the parameter signal representing the shape, such as the size, height, and step, and the material such as color and surface roughness is output. Based on the value of the parameter signal
Skilled designers did it artificially. For this reason, it is difficult to objectively analyze the cause of the occurrence of the pattern defect, and the analysis work of the cause of the defect has not yet been made to improve the inspection efficiency.

The present invention has been made in view of such circumstances, and detects a pattern defect such as a foreign substance or a pattern defect generated on the surface of an inspection object such as a semiconductor wafer.
The main object of the invention is to provide an appearance inspection device that can analyze the cause of the occurrence based on the detection result. The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0005]

The typical ones of the inventions disclosed in the present application will be outlined below. That is, the present invention, the irradiation means for irradiating the inspection object mounted on the sample table with a light beam, and the reflected light is detected to output the parameter signal indicating the characteristic of the pattern defect generated on the surface of the inspection object. The appearance inspection apparatus including the pattern defect detection means, the value of a large number of parameter signals obtained by the pattern defect detection means, the pattern defect classification means for grouping according to the cause of the pattern defect, and grouped The defective mode storing means for storing the defective pattern and the parameter signal obtained by the defective pattern detecting means are compared with the values stored in the mode storing means to determine which group they belong to. A failure mode determination means for determining the cause of the failure is provided.

[0006]

The foreign matter and pattern defect whose shape and the like are detected by the appearance inspection apparatus are automatically classified into modes based on the detection result, so that the cause of the occurrence can be objectively analyzed. Further, it becomes possible to easily perform a more detailed analysis work by using the analysis result.

[0007]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an appearance inspection apparatus of this embodiment, and FIG. 2 is a flow chart showing an analysis procedure by the appearance inspection apparatus.

The appearance inspection apparatus is a sample stage (X-Y stage) on which the semiconductor wafer 1 to be inspected is mounted.
12, a light source (Xe lamp) 13 that irradiates the wafer 1 with inspection light (Xe lamp light), and reflected light detection that detects the Xe laser light (reflected light) reflected on the wafer and outputs a detection signal. Device (CCD sensor) 14, appearance control device 15 for performing analysis processing described later in detail based on the operation control of the appearance inspection device and the inspection signal, storage device 16 for storing the analysis result, and the analysis result And an output device (CRT, printer) 17 for outputting.

Of these, the reflected light detector 14 detects the reflected light that has passed through the imaging optical system 19 and the lens 20 by means of a CCD element. The reflected light detector 14 indicates the intensity, wavelength, etc. of the reflected light applied to the semiconductor wafer 1. It measures and outputs a detection signal according to the measurement result.

The appearance inspection control device 15 controls the step movement amount of the XY stage 12, the scanning direction of the beam by the light source 13, the intensity of the beam, and the like, and controls these states and the reflected light detector 14. Based on the detection signal, the foreign matter (1a) on the wafer, the pattern defect generation position, its shape (size, height, step, etc.), color, etc. are detected. The appearance data (data representing the adhesion position, shape, color, etc.) obtained as a result of the determination by the appearance inspection control device 15 is stored in the storage device 16 in a predetermined manner.

Therefore, the detection of the foreign matter on the wafer, the pattern defect, the shape, the color, etc. is specifically performed as follows. Light for inspecting foreign matter is irradiated onto the entire surface of a specific chip of a semiconductor wafer, and the reflected light is imaged on a reflected light detector (for example, CCD image pickup device) 14 through an imaging optical system 19, and based on the detection signal. To form a chip image in the visual inspection control device 15. A data signal related to a chip image of another chip (having the same pattern formed) that has already been detected and stored in the storage device 16 is read to the control device 15. A difference image of the above two images is obtained, and based on this difference image,
Features of newly generated foreign matter and pattern defects are obtained.

The thus obtained difference image data representing the features of foreign matters and pattern defects is classified according to the cause of occurrence according to the flowchart of FIG. That is, the difference image data obtained by the past appearance inspection is grouped in advance in step 1 according to the cause of failure (mode classification of each difference image data), and stored in the storage device 16 for each mode. In addition, as a mode of classifying the failure modes, for example, the sizes of foreign matters and pattern defects are detected, and depending on the sizes, the A mode (up to 1 μm) and the B mode (1
˜5 μm) and C mode (5 μm-).

On the other hand, the difference image data obtained by the appearance inspection this time is output by the control device 15 (step 2), and the difference image data of each of the failure modes (the storage device 16).
(Data stored in step 3), (step 3),
The difference image data of this time is classified into a failure mode to which data close thereto belongs (step 4). The result of this separation is displayed by the output device 17 (step 5).

In this way, after the failure mode classification (analysis) of the difference image data newly detected this time is automatically performed, further detailed analysis of the cause of the failure occurrence is performed based on this failure mode. Is done.

(Second Embodiment) FIG. 3 is a flow chart showing a method of classifying the difference image data in the defective mode according to the second embodiment. In the second embodiment, a large number of difference image data representing a large number of pattern defects generated on the wafer are detected (step 11), and the characteristics of the obtained plurality of difference image data are compared with each other. Then, those having similar characteristics (size, shape, color, etc.) of the difference image data are classified as the same failure mode (step 12). If the cause of the specific difference image data is to be analyzed in more detail, the failure mode is selected, the difference image data related to this failure mode is extracted, and another analysis method (for example, S
A detailed analysis of the cause of the failure mode is performed by EM analysis) (step 14).

Further, as described above, the foreign matter and the pattern defect on the wafer are detected, while the short / open position of the LSI formed on the wafer is detected and stored and detected. It is also possible to compare the data relating to the pattern defect and this electrical defect data with each other to perform a detailed cause analysis of the electrical defect.

As described above in detail, according to the appearance inspection apparatus of this embodiment, the difference image data representing the characteristics of the foreign matter and the pattern defect detected this time are already analyzed in the inspection apparatus. Since the rough analysis of the cause of the defect can be automatically performed as compared with the other difference image data, the efficiency of the subsequent detailed analysis work can be improved.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, in the present embodiment, the failure modes are classified according to the size of the foreign matter and the pattern defect, but other classification methods such as classification according to other characteristics, for example, outer shape (round shape, square shape) may be used. Good. Further, in the present embodiment, the foreign matter and the pattern defect on the semiconductor wafer are explained, but the present invention is also applicable to other pattern defects such as the foreign matter adhered to the surface of the transfer mask (for example, reticle, 1: 1 mask). Applicable.

[0019]

The effects obtained by the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, one appearance inspection apparatus can detect pattern defects that have occurred on the surface of an inspection object such as a semiconductor wafer and classify them according to the cause of the pattern defects, thus improving the efficiency of defect cause analysis. Planned.

[Brief description of drawings]

FIG. 1 is a block diagram showing an appearance inspection apparatus of this embodiment.

FIG. 2 is a flowchart showing an analysis procedure by the appearance inspection device.

FIG. 3 is a flowchart showing a method for classifying defective modes of difference image data according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 12 Sample stage (XY stage) 13 Light source (Xe lamp) 14 Reflected light detector (CCD sensor) 15 Appearance inspection device 16 Storage device

Claims (4)

[Claims] 1. An irradiating means for irradiating a light beam to an inspection target mounted on a sample stage, and a pattern for detecting reflected light thereof and outputting a parameter signal indicating the feature of a pattern defect generated on the surface of the inspection target. A defect detection means, a pattern defect classification means for grouping the values of a large number of parameter signals obtained by the pattern defect detection means according to the cause of the pattern defect generation, and a defect mode for storing the grouped pattern defects. A failure mode in which the storage means and the parameter signal obtained by the pattern failure detection means are compared with the values stored in the mode storage means to determine which group they belong to and determine the cause of the failure occurrence. An appearance inspection apparatus comprising: a determination unit. 2. The parameter signal represents at least one of size, height, step, color, and surface roughness of a foreign material and a pattern defect that form a pattern defect. Appearance inspection device. 3. An irradiating means for irradiating a light beam to an inspection target mounted on a sample stage, and a pattern for detecting the reflected light and outputting a parameter signal indicating the feature of a pattern defect generated on the surface of the inspection target. Appearance characterized by comprising defect detection means and defect mode classification means for comparing a plurality of parameter signals obtained by the pattern defect detection means with each other and grouping them into those having similar characteristics of pattern defects Inspection device. 4. A plurality of appearance inspection apparatuses are used which detect a pattern defect generated on the surface of the inspection target by irradiating the inspection target mounted on the sample table with a light beam and detecting the reflected light. Data relating to the pattern defect of the inspection object, the collected data is classified into a plurality of modes according to the characteristics of the pattern, and the newly detected pattern defect is classified into the plurality of modes. An appearance inspection method, characterized in that the newly detected pattern defect is classified into which of the above modes by comparing with data, and the cause of defect occurrence is analyzed based on the classified mode.