JPS61200415A - Minute pattern detecting apparatus - Google Patents

Abstract

PURPOSE:To detect rapidly and accurately a detect of a pattern, by irradiating an electrically charged beam onto a specimen, pattern data are stored in a 2-dimension image memory by detecting the reflected particles, and by processing and comparing the data and the normal pattern data with an image calculating apparatus. CONSTITUTION:Scanning of convergent electron beam onto a specimen 27 by the capacity of a 2-dimension image memory, the 2-dimension image memory and an image calculating apparatus in an image calculating apparatus 13 perform filtering, smoothing and binarization of the content of the 2-dimension image memory and by this operation, extraction of the pattern on the specimen 27 is performed on the 2-dimension image memory. In the mean while, a controlling calculating apparatus 11 transmits data stored in an auxiliary storing apparatus 15 to the 2-dimension image memory and to the other sheet of the 2-dimension image memory 13. The image calculating apparatus takes 'OR ELSE' between 2 sheets of the 2-dimension memory. The results represents the pattern defect and the 2-dimension image memory and the image calculating apparatus 13 transmit the position of this detect to the controlling calculating apparatus 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fine pattern inspection apparatus for inspecting fine patterns on masks and wafers, and particularly relates to increasing the speed and precision of the apparatus.

[Conventional technology]

A conventional device of this kind is shown in FIG. 2. In FIG. 0, 24 is a sample to be inspected, 21 is a light source, 22 is an aperture for shaping the irradiation zone, 23 is a converging lens, and 25 is an image sensor. . Further, 14 is a stage control circuit for moving the sample to be inspected 24, 13 is an image memory and an image arithmetic unit, 11 is a control arithmetic unit, and 15 is an auxiliary storage device in which inspection data is stored.

Next, the operation will be explained.

The light emitted from the light #21 is shaped by the aperture 22, converged by the converging lens 23, and irradiated onto the sample 24 to be inspected. The transmitted light having bright and dark areas corresponding to the pattern on the sample to be inspected 24 is irradiated onto the image sensor 25, and a signal is read out according to the intensity of light on each pixel, and is stored in the image memory 1.
3. The stored image data is then subjected to processing such as filtering, smoothing, and binarization. On the other hand, the inspection pattern data is stored in the auxiliary storage device 15.
and stored in another image memory. This 2
By comparing the values on the two image memories with the control calculation device 11, defects in the pattern of the sample to be inspected 24 are extracted, and furthermore, the position is calculated using the stage position as data,
The operator is informed of the defect position on the sample 24 to be inspected.

[Problem that the invention seeks to solve]

Since conventional pattern defect inspection equipment is configured as described above, the edges of the acquired pattern are blurred to the same extent as the wavelength of light, but the accuracy has been improved by image processing. However, as processing technology advances, patterns have become finer and pattern widths have entered the submicron range, and such optical methods are approaching the limits of accuracy.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a fine pattern inspection apparatus capable of detecting pattern defects at high speed and with high precision.

[Means for solving problems]

The fine pattern inspection device according to the present invention includes a focused charged beam irradiation device that irradiates a charged beam onto a sample to be inspected and detects reflected particles or secondary particles, and a signal from the detector that stores the signal as a digital signal. The system is equipped with an image processor for extracting pattern defects.

[Effect]

In this invention, a charged beam having high resolution is irradiated onto a sample to be inspected such as a mask or a wafer, the reflected particles are detected, and pattern data on the sample to be inspected is stored in a two-dimensional image memory. Data and regular inspection pattern data are processed and compared using a dedicated image processor to detect pattern defects at high speed.

Detect with high precision.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a fine pattern inspection apparatus according to an embodiment of the present invention. In the figure, 30 is a focused charged beam irradiation device,
In the apparatus 30, 21 is an electron beam gun as a charged beam irradiation means, 22 is an accelerating electrode, 23 is an aperture, 24 is a focusing lens, and 25 is an electron beam irradiation means for directing the electron beam to the sample to be inspected 2.
7 is a deflection electrode for scanning, 26 is a sample to be inspected 27;
A detector 28 that detects reflected electrons or secondary electrons from the sample 27 is a stage that holds the sample 27 to be inspected.

Further, 12 is a scanning signal that generates a scanning signal 16 to be applied to the deflection electrode 25 and a synchronization signal 17 for memory writing.
Synchronous signal generator (hereinafter referred to as scanning/synchronizing signal generator),
13 is a two-dimensional image memory and an image arithmetic unit (not shown in the figure, but the two-dimensional memory is a ), 14 is a stage control circuit, 11
15 is a control arithmetic unit, and 15 is an auxiliary storage device for storing test data.

Next, the operation will be explained.

In FIG. 1, the electrons emitted from the electron beam gun 21 are
Accelerated by an accelerating electrode 22, shaped by an aperture 23,
The light is focused by the focusing lens 24 and irradiated onto the sample 27 to be inspected. At this time, the scanning/synchronizing signal generator 312 sends the scanning signal 16 to the deflection electrode 25, so that the electron beam is scanned over the sample 27 to be inspected. Then, the reflected electrons or secondary electrons from the sample to be inspected 27 are detected by the detector 26. This detection signal is sent to a two-dimensional image memory and image calculator 13, and the two-dimensional image memory and image calculator 13 A/D converts the signal 18 from the detector 26 and stores it in the two-dimensional image memory. Store.

The memory address at this time is the scanning/synchronization signal generator 12.
It is generated by the synchronization signal 17 from. In this way,
After the focused electron beam scans the sample 27 to be inspected for the capacity of the two-dimensional image memory, the two-dimensional image memory and image processor in the image processor 13 filter and smooth the contents of the two-dimensional image memory. By performing binarization, a pattern on the specimen 27 to be inspected, such as a resist pattern or a pattern after etching, is extracted onto a two-dimensional image memory. By performing these processes using a dedicated image arithmetic unit, high-speed image processing becomes possible. During this time, the control calculation device 11 sends the inspection data stored in the auxiliary storage device 15 to the two-dimensional image memory and another two-dimensional image memory of the image calculation unit 13. Loading the detection signal into two two-dimensional memories and image processing;
After each inspection data transfer is completed, the two-dimensional image memory and the dedicated image computing unit of the image computing unit 13 calculate the exclusive OR between the two two-dimensional memories. This result is a pattern defect, and the two-dimensional image memory and image arithmetic unit 1
3 sends the position of this defect to the control arithmetic unit 11.

In this embodiment, since the focused charged beam irradiation device has high resolution, pattern defect inspection can be performed with high precision. Furthermore, since the sample pattern detection signal is taken into a dedicated image processor and processed, high-speed processing can be performed.

In the above embodiment, a focused charged beam irradiation device using an electron beam as a light source is used, but an ion beam gun may be used instead of the electron beam gun, and the same effect as described above can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the fine pattern inspection apparatus is configured to use a high-resolution focused charged beam irradiation device and to capture pattern detection signals of the sample with a dedicated image processor and perform calculation processing. This has the effect of enabling high-precision, high-speed pattern defect inspection.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional pattern defect inspection apparatus, and FIG. 2 is a schematic diagram of a fine pattern inspection apparatus according to an embodiment of the present invention. In the figure, 11 is a control calculation device, 12 is a scanning/synchronization signal generator, 13 is a two-dimensional image memory and image calculation unit, 16 is a scanning signal, 17 is a synchronization signal, 18 is a detection signal, 21 is an electron beam gun, 22 is an accelerating electrode, 23 is an aperture, 24
25 is a focusing lens, 25 is a deflection electrode, 26 is a detector, 27 is a sample to be inspected, 28 is a stage, and 30 is a focused charged beam irradiation device.

Claims (2)

[Claims] (1) A fine pattern inspection apparatus for inspecting defects in a fine pattern formed on a sample to be inspected, which includes a charged beam irradiation means, a scanning means for scanning the charged beam on the sample to be inspected, and the above-mentioned A focused charged beam irradiation device having a detector for detecting reflected particles or secondary particles from a sample to be inspected, and a scanning signal/synchronization signal for generating a scanning signal for driving the scanning means and a synchronization signal for writing to the memory. a generator, a two-dimensional image memory that A/D converts the signal from the detector and stores the digital signal based on an address signal generated by the synchronization signal for writing to the memory; A fine pattern inspection apparatus comprising: an image calculator that compares the stored pattern on the sample to be inspected with regular inspection pattern data to extract pattern defects on the sample to be inspected. (2) The image arithmetic unit extracts the pattern defect by obtaining an exclusive OR of the data obtained by filtering, smoothing, and binarizing the data in the two-dimensional image memory and the regular inspection pattern data. A fine pattern inspection device according to claim 1, characterized in that: