JPS63289815A - Inspection of photomask - Google Patents

Abstract

PURPOSE:To enable the reduction of inspecting time and the confirmation of circuit modifying position on data base, by storing, as a data base, the information of modifying position part before circuit modifying. CONSTITUTION:In the case where a photomask 4 to be inspected is one in which some modification is performed, a magnetic tape 2 in which information D2 concerning to circuit modifying part before modification is stored is offered by CAD processing, and converted into comparison data D3 by a data converter 3. The coordinate information is input to a stage controller 11, which controls a stage 5. A pattern of modifying part of a photomask is converted into comparison data D5, by an photoelectric converter 7 via an optical system 6. The comparison data D5 and the comparison data D3 are compared by a comparing part 8, and the compared information is stored in a failure pattern memory 9. It is displayed on a CRT 10, and applied to the pattern confirmation of modifying part. Thereby, the precise visual confirmation for the modifying part of a real photomask pattern is enabled, and the working hour is reduced because a stage scanning region is limited.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for inspecting photomasks used in the manufacture of semiconductor integrated circuits.

2. Description of the Related Art When manufacturing semiconductor integrated circuits, in order to expose a semiconductor substrate to a predetermined structural pattern, the same pattern is
A photomask consisting of a glass substrate magnified twice is used. Therefore, inspection of this photomask becomes an important process that determines the manufacturing yield and quality of semiconductor integrated circuits. Currently, the following four methods are combined as photomask inspection methods. First, a visual inspection method in which an operator observes the actual photomask pattern using a microscope and detects any abnormalities.Secondly, two actual photomask pattern images obtained through a pair of microscopes are optically inspected. A visual pattern comparison inspection method that compares and detects differences. Third, an automatic pattern comparison inspection method that converts and compares adjacent repeating photomask patterns into electrical signals and detects differences. Fourth, a photoelectric conversion system There is an inspection method using a database that compares and checks the pattern data of the obtained actual photomask pattern with the original pattern data when manufacturing the same photomask.

The actual photomask inspection method begins with five steps to expose a pattern on a mask substrate or semiconductor substrate.
The above-mentioned fourth inspection method is used to inspect a reticle that has been enlarged 10 times, and the above-mentioned third automatic pattern comparison inspection method is used to inspect a mask that has been reduced by 115 to 1/10. When a part of the circuit of a photomask is modified, a second visual comparison inspection method is used to confirm the circuit modification location. Note that the first visual inspection method described above is not often used in mass production processes because the inspection takes time and inspection errors are likely to occur.

FIG. 4 shows a schematic diagram of photomask inspection using the database method described above. Original pattern data (design data) D+ equivalent to that used to create a photomask is stored on the magnetic tape 1. The pattern data D1 is converted into a comparison signal D4 in the conversion section 3.

Further, the optical signal D7 of the photomask pattern obtained from the photomask 4 to be inspected by the optical system 6 is transmitted to the image sensor.
The original pattern signal D4 obtained from the original data converter 3 is converted into a pattern output signal D5 by the optical converter 7 such as
It is compared with the comparator 8 and outputted to the outside 19.

Problems to be Solved by the Invention However, when confirming partial changes to a photomask that has already been manufactured, the inspection method using this database does not allow the circuit modification locations to be confirmed on the photomask, and on the other hand, when using the visual comparison inspection method, the inspection time is reduced. The problem was that high detection accuracy could not be obtained due to the long period of time.

The present invention solves the above-mentioned problems, and aims to provide a database-based inspection method that shortens inspection time and makes it possible to confirm circuit correction locations on the database.

Means for Solving the Problems In order to achieve this object, the photomask inspection method of the present invention has a configuration in which a database contains information on the parts to be corrected before circuit correction in a database-based inspection method.

Effects With this configuration, even when comparing the database and photomask pattern data, it is possible to check the comparison with the original pattern data and the circuit correction part with the before correction.
It is possible to shorten the inspection process time and achieve high detection accuracy.

Further, the information on the modified portion before the circuit modification can be output at the same time when photomask pattern data is subjected to CAD processing.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, first, the original pattern data D+ equivalent to that used to create the photomask and the optical signal D7 of the photomask pattern obtained from the photomask 4 to be inspected by the optical system 6 are used. , the comparison section 8 performs a comparison test using a normal database method. Next, when the photomask 4 to be inspected is remade with a part of the pattern changed, the information D2 before the correction of the circuit correction part is
A magnetic tape 2 on which data has been stored is provided by CAD processing, and is converted into comparison data D3 by a data converter 3. The coordinate information of the corrected portion of the comparison data D3 is input to the stage controller 11 to control the stage 5 on which the photomask 4 to be inspected is placed.

Then, the pattern of the corrected portion of the photomask is converted into comparison data D5 by the optical conversion device 7 via the optical system 6. This comparison data D5 and the comparison data D3 before correction are compared by the comparison section 8, and the comparison information is stored in the defective pattern memory 9 and output to the CRTIO to check the pattern of each correction location.

FIG. 2 shows an example of the pattern before and after circuit modification. Same figure A
is the pattern before modification, and after modification, as shown in FIG. 2B, partial pattern 14 of pattern 12 is removed and pattern 15 is added.

Comparison unit 8 compares and display means, for example,
A diagram output to the CRTIO is shown in FIG. For example, if the photomask pattern data D5 is shown in red and the uncorrected information D3 of the corrected portion is shown in green, the uncorrected part 16 is shown in purple, the removed part 17 is shown in red, and the added part 18 is shown in red.
is displayed in green. This allows accurate visual confirmation of the pattern correction location. Furthermore, since the stage scanning range is limited by the coordinate information D3 of the corrected portion, the scanning time is short, and work efficiency can be significantly improved compared to the conventional visual pattern comparison inspection method.

Effects of the Invention As described above, the photomask inspection method of the present invention has information on the modified portions before circuit modification as a database, and therefore visual confirmation of the modified portions of the actual photomask pattern can be performed with high accuracy. , and since the stage scanning range is limited, the working time is shortened, which greatly contributes to making the photomask defect-free and shortening the photomask manufacturing process and semiconductor element manufacturing period. In particular, according to the present invention, information on the modified portion before the circuit modification can be processed simultaneously and easily when the design data after the circuit modification is subjected to CAD processing, which is extremely advantageous in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a photomask inspection method according to an embodiment of the present invention, FIGS. 2A and B are plan views schematically showing patterns before and after circuit modification, and FIG. FIG. 4 is a plan view showing an embodiment in which comparison data of a portion is outputted to a CRT, and FIG. 4 is a block diagram of a conventional photomask inspection method. 1...Magnetic tape on which original pattern data (design data) is stored, 2...Magnetic tape on which data before modification of the circuit modification portion is stored, 3...
...Data converter, 4...Photomask to be inspected, 7...Photoelectric converter, 8...Signal comparison section, 1o...Comparison data A CRT that outputs. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2 tA) 4- Exorcist V Dern CB) 15°-#Nakaoba'-'

Claims (1)

[Claims] A photomask inspection method that uses a photomask whose circuit has been corrected to check the corrected areas using information on the corrected areas before circuit correction as a database.