JPS582844A - Inspecting method for photomask - Google Patents

Abstract

PURPOSE:To greatly simplify an inspecting stage for a working photomask by providing an optical system, a storage device, an arithmetic device, etc., for the inspection of the working photomask manufactured by using a common master photomask. CONSTITUTION:Firstly, the entire surface of a common master photomask 3 is inspected to find all faults, and whether each fault is harmful or not is judged to correct a harmful fault. The position of the area where a fault judged to be harmful substantially is present is stored in a storage device 4. Then, the entire surface of an optional working photomask is inspected to find all fault without discriminating between harmful and harmless faults, and positions of their areas are stored in the device 4. Then, the information obtained by subtracting information on a harmless fault that the master photomask 3 has from information on a fault of the workig photomask is regarded as information on the area of a harmful fault that the working mask manufactured before the working photomask detected in a manufacture lot has. This area is accessed and set in the visual field of an optical system 1 to perform correction.

Description

[Detailed description of the invention] The present invention relates to a photomask inspection method.

In detail, this article relates to the abbreviation of photomask inspection.

Photomasks are easy to wear out and require a large quantity, so it's a bit of a turnaround.
It is common for people to create a working photomask and use this working photomask in the photophosphorography method. The common master photomask line is manufactured with great care so that there are no defects, but since the turns are extremely fine, it is difficult to make the common master photomask line completely defect-free. In many cases, the master photomask is inspected and found to be virtually harmless, without making any modifications.As a result, the master photomask contains a significant number of harmless defects. is common.

By the way, K-A9.9. manufactures a working photomask by reverse baking this common mask photomask. Since it is inevitable that some defects may occur,
In the conventional technology, in principle, the entire amount of manufactured working photomasks is inspected, and moreover, the entire surface thereof is inspected.

The number of man-hours required for this was difficult to form an image. Moreover,
In this full inspection, all of the harmless defects that have been included in Todoroki's mask photomasks from the beginning are naturally detected, and after screening and removing them, only the defects that are actually harmful are corrected. However, there was a major drawback in that the amount of man-hours required for this virtually unnecessary work was enormous.

The object of the present invention is to provide a method for inspecting nine working photomasks manufactured using a common master photomask.
It is an object of the present invention to provide a method for inspecting a photomask in which the inspection process is simplified.

The gist is that (a) it is possible to determine the physical state of a minute area on the photomask surface, such as the presence or absence of a specific substance, the transmission/non-transmission, reflection/absorption, or potential of a specific electromagnetic wave or particle; an optical system, a scanning stage system that scans the optical system so that the optical system can sequentially operate on each of the nine small areas that are provided by subdividing the photomask surface; It has a storage device that stores information such as system output information, a device that writes information to and reads information from the storage device, an arithmetic device, and a control device that issues commands to sequentially execute inspection steps. Assuming that a photomask inspection device is used, (b) First,
First, the entire surface of the common master photomask is inspected to find all defects, and any harmful defects are corrected, and defects that are confirmed to be harmless are imaged. The position of a micro region or a group of micro regions in which a harmless defect exists is stored in a memory location (f1, then
) The entire surface of any working photomask is inspected to find all defects, and the positions of the existing minute regions or groups of minute regions are temporarily stored in a storage device.
Compare the information regarding FfMo 1; 4 photomask with the previously stored information regarding the 9th master photomask, delete the mutually overlapping portions from the information regarding 1 working photomask, and (4) with the remaining 9 information,! ! & Information indicating the position of a small mold area or a group of small mold areas in which defects exist in all nine working photomasks manufactured before the above-mentioned actually inspected working photomasks in the manufacturing lot and the image. To do so #)'ru.

Then, for each of the nine working photomasks manufactured before the nine working photomasks subjected to the actual WAK inspection, the defects existing at the positions represented by the information stored in the storage device are successively corrected. In other words, if an area that should transmit electromagnetic waves is opaque, that small area should be irradiated with a single laser beam to scatter an opaque substance to correct the problem, and conversely, it should be opaque to electromagnetic waves. When a region is transparent, it is corrected by making the region opaque by spraying an inkjet onto the micro region.

As a result, by actually inspecting a very small number of working photomasks, only the harmful defects of a very large number of working photomasks can be detected with very high accuracy. It also depends on the quantity of the relevant manufacturing lot. However, it is sufficient to detect one in nine working photomasks manufactured at the end of one manufacturing lot. Therefore, in many cases, it is sufficient to inspect only one circle in each manufacturing loft, which greatly simplifies the inspection process of the detection method for working photomasks manufactured using a common master photomask. be able to.

The laws of nature on which the present invention relies are that (a) there is a considerable proportion of defects in the 7th mask that are actually harmless, and (b) defects in the working photomask are caused by wear and tear on the master photomask.・There is a tendency for defects to increase due to damage, and in each production lot, there is a very high probability that a defect that does not exist in a 9-working photomask manufactured after the first one will exist in a 9-working photomask manufactured before that. The fact is that there are few.

Hereinafter, one embodiment of the present invention will be described with reference to the ai1 page, and the configuration and unique effects of the present invention will be further clarified.

(2) The reference figure shows a block diagram of an inspection device used in the photomask inspection method according to the present invention.

In the figure, 1 is an optical system, 2 is a scanning wrinkle stage system, and 3 is a photomask to be inspected. Number is a storage device, number 5 is an arithmetic device, and number 6 is a control device. The scanning lid stage system 2t scans the surface of the photomask 30, which is virtually divided, and inspects each small area with the optical system 1, and stores the results in the storage device 4.◎ Control The device 6 uses the arithmetic device 6 to initially control the progress of the inspection process according to a predetermined program.

First, we inspect the entire surface of the common master photomask, find all defects, determine whether they are harmful or non-hazardous, and correct any harmful tortoises using the method shown above (laser irradiation or inkjet). Rub. This process can be done visually or automatically by storing a model in a storage device number and comparing it with this. The location of the area where the defect, which is determined to be virtually harmless, is stored in the storage device 4.

Next, carry out a complete inspection of any working photomask,
All defects, regardless of whether they are harmless or not, are discovered and the positions of the areas are stored in a storage device 4. This step can also be done visually or by automatically comparing it with a model stored in the storage device 4.

Thirdly, with the information given by subtracting the information about harmless defects contained in the master photomask from the information about defects in the working photomask, it is possible to determine whether the working photomask was manufactured before the actually detected working photomask in this manufacturing loft. All of the working photomasks that have been processed are imaged with information indicating the harmful defects, that is, the areas where repair defects are present.

Based on this information, in the corresponding production lot, 9 working photomasks have been inspected 11 times.
For each of the nine working photomasks, the area in which the harmful defect exists is sequentially called into the field of view of the optical system 1 and corrected.As explained above, according to the present invention, a common master photomask is used. According to the present invention, it is possible to provide a photomask inspection method in which the inspection process is greatly simplified in the nine-working photomask inspection method manufactured by the present invention.

However, it is extremely easy to store the above-mentioned sample and model in a storage device and proceed with the inspection process according to the present invention completely automatically, and furthermore, the correction process of each working photomask can also be completely performed. As an automatic process, it is also possible to provide a fully automatic photomask inspection and repair apparatus using the present invention.

[Brief explanation of the drawing]

The figure is a block diagram of a photomask inspection device that is directly used to carry out a photomask inspection method according to an embodiment of the present invention. 1...Optical system, 2...Scanning stage system. 3...Detected photomask, number...
・Storage device, 5... Arithmetic device, 6...
·Control device.

Claims (1)

[Claims] an optical system for determining the physical state of a microscopic area of 11 photomask images; a scanning system for sequentially changing the relative positional relationship between the optical system and the optical system; a storage device in which information such as output information of the optical system is stored; and a device for writing and reading information into the storage device. In a method for inspecting a photomask using a photomask inspection device having a calculation device and a control device for instructing sequential execution of inspection, (1) a common master photomask is inspected and the (b) storing in said storage device the location of said micro-region or micro-regions containing defects that are present but are confirmed to be harmless; f) Inspecting the nine working photomasks manufactured in 1999 to discover the position of the minute area or group of minute areas where defects exist, and storing the position in the storage device, and f) using the information and the step (1) above. (b) comparing the stored nine pieces of information and selecting the different information; and a) using the selected nine pieces of information, select a working photomask manufactured before the working photomask inspected in the step (0) in the manufacturing unit. 1. A method for inspecting a photomask, characterized in that information representative of the positions of minute regions or groups of minute regions in which defects exist in all working photomasks is considered.