JPH045978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning device for exposure masks used in the manufacture of semiconductor devices, and in particular, it automatically detects pattern defects caused by dust and stains remaining on the exposure mask after cleaning. The present invention relates to an apparatus for determining the quality of cleaning results by comparing the results of detecting defects with a preset standard for residual pattern defects that are determined to be non-defective products, and re-cleaning the exposure mask if the result is negative.

As with the manufacturing process of recent ultra-highly integrated semiconductor devices, quality control after cleaning of exposure masks, which requires high quality and no defects, is an important factor that influences the yield rate of semiconductor devices obtained from semiconductor substrates. Therefore, it is particularly important to control pattern defects caused by dust and stains caused by resident foreign matter that remain on the exposure mask even after cleaning.

In conventional exposure mask cleaning equipment, defects caused by dust and stains are managed in some cases by directly scanning and observing the entire surface of the exposure mask after cleaning using a microscope, and in other cases, the exposure mask is mounted on the exposure device. However, the photoresist pattern obtained by exposing a semiconductor substrate coated with photoresist to light is scanned and observed over the entire surface using a microscope. The time and effort required for this observation are immeasurable, and the time and effort required to remove pattern defects and obtain a good exposure mask are also immeasurable.

SUMMARY OF THE INVENTION An object of the present invention is to improve the yield rate of semiconductor devices by eliminating the above-mentioned problems of the conventional cleaning apparatus and by obtaining an exposure mask free from pattern defects due to dust, stains, etc.

According to the present invention, an exposure mask protective case storage section is provided with an exposure mask protective case in which an exposure mask having a plurality of repeating patterns is stored;
A cleaning section that cleans this exposure mask, and an exposure mask carried out from this cleaning section are placed on a stage, and a light beam is transmitted through parts of the exposure mask that correspond to two sequentially selected repetitive patterns. The transmitted light is optically detected, the respective detection results are compared, and the remaining pattern is detected by moving the stage and performing a defect inspection on the entire surface of the exposure mask. An automatic defect detection/processing unit that determines the quality of the cleaning result by comparing the result of detecting defects with a preset standard for residual pattern defects that are determined to be non-defective products; The exposed mask is transported from the protective case storage section to the cleaning section, and the exposed mask after cleaning is automatically detected from the cleaning section.
If the cleaning result is negative, the exposure mask is transported to the processing section, and if the cleaning result is negative, the exposure mask is automatically detected for defects.If the cleaning result is good, the exposure mask is automatically detected for defects.
An exposure mask cleaning device is provided which has a conveying means for conveying an exposure mask from a processing section to an exposure mask protective case storage section. The thus obtained non-defective exposure mask is protected from floating dust and the like by the exposure mask protection case.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. Figure 1 shows a schematic diagram of the entire exposure mask cleaning equipment including the exposure mask cleaning section, automatic defect detection/processing section, and exposure mask protective case storage section, and Figure 2 shows the defect detection section of the automatic defect detection/processing section. FIG. 2 is an explanatory diagram of an observation system for In the figure, 1 is an exposure mask cleaning device, 2 is an exposure mask cleaning section, and 3
is an automatic defect detection/processing section, 4 is an exposure mask protective case storage section, 5 is a defect detection data output section, 6 is an exposure mask, 7 is a laser head (including scanner),
8 is a photodetector, 9 is a pattern defect, 10
11 is an objective lens, 11 is a half mirror, 12 is a stage scan direction, 13 is a mirror, and 20 is a conveyance means.

The exposure mask is transported in the exposure mask cleaning apparatus 1 in the following order. First, the exposure mask protective case containing the exposure mask to be cleaned is attached to the exposure mask protective case storage section 4.
Next, the exposure mask is automatically transported from the exposure mask protection case in the exposure mask protection case storage section 4 by the transport means 20 via the automatic defect detection/processing section 3 to the exposure mask cleaning section 2, where it is subjected to various cleaning processes. After that, the cleaning unit 2 is transported back to the automatic dust detection/processing unit 3 by the transport means 20. The exposure mask 6 carried out from the cleaning section 2 is placed on a scan stage provided in the automatic defect detection/processing section 3, and the observation system shown in FIG. A pattern is observed. In the observation system, first, the repeating patterns on the exposure mask 6 are superimposed on two sequentially selected CRTs to align the exposure mask 6. As a result, corresponding portions of the two selected patterns are positioned between the objective lens 10 and the photodetector 8, respectively. The laser beam from the laser head 7 above the exposure mask 6 is divided by a half mirror 11 into two laser beams, one straight and one reflected. The light passes through corresponding portions of the two repeated patterns of the exposure mask 6, and the transmitted light is optically detected by two photodetectors 8, and the two outputs are compared. If there is a difference between the two outputs obtained by this observation system, it is determined that the pattern is defective due to residual dust, stains, etc. The scan stage is scanned in the stage scan direction 12 in Fig. 2 and moved in a direction perpendicular to this direction to scan the entire surface of the exposure mask, and this scanning operation removes dust, stains, etc. on the exposure mask. Perform defect inspection to detect pattern defects. In this detection process, the size of a pattern defect can be detected at different times when the two outputs are different, and the number of pattern defects can be detected at different times when the two outputs are different. The results of detecting the size and number of residual pattern defects are output from the automatic defect detection/processing section 3 to the CRT of the defect detection data output section 5 for confirmation by the operator, and are also sent to the automatic defect detection/processing section 3 in advance. The quality of the cleaning result is determined by comparing the size and number of residual pattern defects that are determined to be non-defective. If it is confirmed that defects larger than the standard size or number have been removed under the control of the automatic defect detection/processing section 3, the cleaning result is good, and the exposure mask is automatically transferred to the automatic defect detection/processing section by the conveying means 20. 3 to the exposure mask protective case storage section 4 and stored in the exposure mask protective case therein. If the cleaning result is negative, the exposure mask is transported from the automatic defect detection/processing section 3 to the cleaning section again by the transport means 20, where it is cleaned, and then transported to the automatic defect detection/processing section 3. , the pattern defect 9 is inspected again. If the cleaning result is negative again, the cleaning and defect inspection are repeated in the same way, and if the cleaning results are good within the limit number of times set in advance in automatic defect detection/processing 3, the exposure mask is automatically inspected.
It is transported from the processing section 3 and automatically stored in the exposure mask protective case in the exposure mask protective case storage section 4, completing cleaning in this apparatus.

As mentioned above, the number and size of defects such as stains caused by residual dust and foreign matter on the exposure mask after cleaning are managed by the pattern comparison inspection mechanism, and the exposure mask supplied from this device is of good quality. This has been confirmed, and the dust and stains that were present during manual inspection are now gone, making it possible to dramatically improve the quality of semiconductor devices produced by using this exposure mask. Become. In addition, when applied to a reduction projection exposure system (stepper), it is possible to directly handle a good product while it is stored in the exposure mask protective case, so no dust is removed from the time the product is confirmed to be good by cleaning until it is attached to the stepper. It becomes possible to eliminate the possibility of adhesion, easily eliminate common defects in repeated patterns transferred onto a semiconductor substrate, and dramatically improve the efficiency of use of the stepper. Therefore, the practical effects of the present invention are extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, showing the entire exposure mask cleaning apparatus, and FIG. 2 is an explanatory diagram of defect detection in an automatic defect detection/processing section that is a part of the apparatus. In the figure, 1... Exposure mask cleaning device, 2... Exposure mask cleaning section, 3... Automatic defect detection/processing section, 4
... Exposure mask protective case storage section, 5 ... Defect detection data output section, 6 ... Exposure mask, 7 ... Laser head (including scanner), 8 ... Photo detector, 9 ... Pattern defect, 10 ... ...Objective lens, 11...Half mirror, 12...Stage scan direction, 13...Mirror, 20...Transporting means.

Claims (1)

[Claims] 1. An exposure mask protective case storage section into which an exposure mask protective case containing an exposure mask having a plurality of repeating patterns is mounted, a cleaning section that cleans the exposure mask, and the exposure mask carried out from the cleaning section. is placed on a stage, a light beam is transmitted through corresponding portions of the two sequentially selected repetitive patterns on the exposure mask, the transmitted light is optically detected, and the respective detection results are compared. After performing a defect inspection to detect pattern defects due to residual dust, stains, etc. due to the difference, by moving the stage and performing a defect inspection on the entire surface of the exposure mask, the residual pattern defects are detected and the product is determined to be non-defective as determined in advance. an automatic defect detection/processing unit that determines the quality of the cleaning result by comparing it with a standard of residual pattern defects, and an automatic defect detection/processing unit that carries the exposure mask to be cleaned from the exposure mask protective case storage unit to the cleaning unit and cleans it. The subsequent exposure mask is transported from the cleaning section to the automatic defect detection/processing section, and if the cleaning result is negative, the exposure mask is transported from the automatic defect detection/processing section to the cleaning section again to check the cleaning result. An exposure mask cleaning apparatus comprising: a conveying means for conveying the exposure mask from the automatic defect detection/processing section to the exposure mask protective case storage section when the defect is good.