JPS6315572B2 - - Google Patents

Description

Detailed Description of the Invention: a Field of Industrial Application The present invention is a mask repair device using an ion beam for a photomask used in a semiconductor integrated circuit manufacturing process, which is used to observe defective parts of a mask and designate areas for repairing the defective parts. The present invention relates to an image display device that can perform image processing without damaging a mask.

b. Prior Art Conventionally, an apparatus for repairing defective parts of a mask by irradiating the mask with an ion beam focuses the ion beam on the mask surface and scans it, while measuring the intensity of secondary charged particles generated at that time. is converted into an electrical signal by a secondary charged particle detector, and the output signal is guided as a video signal input of an image display device. While observing the defective part of the mask displayed on the image display device, the defect correction area is designated. The defects are corrected by irradiating the mask with an ion beam.

c Problems to be solved by the invention In the method described in section b, while scanning an ion beam over a mask, the secondary charged particle intensity generated at that time is converted into an electrical signal by a secondary charged particle detector. When trying to confirm the defective part and designate the repair area while observing the image by guiding the output signal to the video signal input of the image display device, the ion beam is always masked during these operations. Therefore, the area of the mask that is irradiated with the ion beam is etched by the etching action of the ion beam. If the mask is unnecessarily removed by the ion beam,
As shown in Figure 2, walls are formed, and things that have been etched and blown away accumulate and form mountains, making it difficult for light to pass through during the original purpose of exposure. This has the disadvantage that it causes diffuse reflection and is exposed as if it were a chrome pattern.

d Means for solving the problem The intensity of secondary charged particles generated when the ion beam mask is scanned is converted into an electrical signal by a secondary charged particle detector, and the electrical signal is guided to a memory circuit. In response to the memory start signal, the voltage applied to the blanking electrode is turned off, the ion beam is irradiated onto the mask, frame scanning is started in accordance with the start signal, and the electricity from the secondary charged particle detector is The signal starts to be stored in the memory circuit, and when one frame of scanning is completed, a scanning completion signal is generated, and according to the completion signal, a predetermined voltage is applied to the blanking electrode to stop irradiation of the ion beam onto the mask. A means for observing a defective area, specifying a correction area, etc. using an image obtained by guiding a video signal stored in a storage circuit to a video signal input of an image display device.

e Effect: In response to the storage start signal, irradiation and scanning of the ion beam is started, the intensity of the secondary charged particles generated at that time is converted into an electrical signal by a secondary charged particle detector, and the electrical signal is guided to the storage circuit. Ion beam irradiation is stopped in response to a frame scanning completion signal, and subsequent operations are performed using images obtained by guiding the video signal stored in the memory circuit to the image display device.
The objective is to observe the mask and correct defective areas.

f Examples Examples of the present invention will be described below with reference to the drawings. In FIG. 1, the ion beam emitted from the liquid metal ion source 1 is normally deflected by the planking electrode 2 and is not irradiated onto the mask 3, but when the storage start switch 4 is turned on, the scanning signal generator 5 The scanning signal from is amplified by the scanning signal amplifier 6 and applied to the deflection electrode 7 to start scanning. At the same time, an unblanking signal is generated from the scanning signal generator and amplified by the voltage amplifier 8, and the ion beam is focused by the focusing lens 9 onto the mask and scanned by the aforementioned action. The secondary charged particle intensity generated by scanning the ion beam mask is converted into an electrical signal by the secondary charged particle detector 10, amplified by the video signal amplifier 11, and converted into an analog signal by the analog-to-digital converter 12. is converted into a digital quantity by
3 and 3 are sequentially stored in accordance with a storage control signal output from a scanning signal generator. When one frame of scanning is completed, a blanking signal is generated from a scanning signal generator, amplified by a blanking voltage amplifier, blanking the ion beam, and stopping irradiation of the ion beam onto the mask. At the same time, the storage control signal from the scanning signal generator is stopped and storage in the storage circuit is stopped. Further, a display start signal is generated from the scanning signal generator, and the digital quantity stored in the storage circuit is read out by the readout control signal generated from the scanning signal generator 16 of the image display device 15, and the digital quantity is read out by the digital to analog converter 17. To irradiate the unnecessary beam by converting it into an analog signal, amplifying it by the video signal amplifier 18, and guiding it as a video signal input of the image display device that is scanned by the scanning signal of the scanning signal generator of the image display device. Therefore, it is possible to observe defective parts of the mask and defect repair areas.

Appropriate times are selected as the ion beam scanning time for storing and the scanning time after storing. Also, although only one frame was scanned for storage, it is also possible to scan two or more times and add the signals from the secondary charged particle detector, that is, reduce the ion beam current and increase the number of scans. This is because, in the end, the degree of damage to the mask is the same.

Although not shown in the embodiment, the two scanning signal generators are combined into one, and during scanning for storage,
It is easily possible to add the function of scanning an image display device and observing while storing the image.

In addition, as a secondary charged particle detector, g
The intensity of the secondary charged particles at that time is detected by a secondary charged particle detector, which is guided to the memory circuit, and the image of the mask is displayed based on the signal stored in the memory circuit, and various operations are performed based on the signal stored in the memory circuit. By the way,
Unnecessary ion beam irradiation can be avoided.

[Brief explanation of the drawing]

FIG. 1 shows a mask repair apparatus according to the present invention. FIG. 2 is a diagram for explaining the present invention. 10... Secondary ion detector, 13... Memory circuit.

Claims (1)

[Claims] 1. An ion beam from a high-brightness ion source such as a liquid metal ion source is focused and scanned onto the mask surface using a charged particle optical system, and the intensity of the secondary charged particles generated at that time is detected using a secondary charged particle detector. In a mask repair device using an ion beam, which converts the electrical signal into an electrical signal and guides the electrical signal as a video signal input of an image display device to observe defective parts of the mask, after converting the electrical signal into a digital signal,
1. A mask repair device using an ion beam, which is stored in a memory circuit and displays an image of the mask based on the output of the memory circuit.