JPS5832416A - Inspection for pattern defect - Google Patents

Abstract

PURPOSE:To detect foreign substances with a high reliability, by a method wherein a plurality of chips are transferred onto a substrate, and one of them is compared with another. CONSTITUTION:Foreign substances 104, 105 and circuit patterns 106 are on a reticle 103. The probability is substantially zero that the positions of the foreign substances on the respective chips and the configurations thereof are completely the same. When transferred images are formed on a photoresist on a transparent glass, transferred images 116 of the circuit patterns appear on the whole chips, but trasferred images 114, 115 of the foreign substances appear every two chips. Objective lenses 118, 119 are disposed above chips 112, 113 respectively, and a glass plate 107 is irradiated 120. The light is photoelectrically converted 121, 122 and amplified 123, 124 and then differentially amplified 125 before being delivered 126. A holder 117 is moved in the X and Y directions to detect the existence of a defect in the whole chip aea, i.e., the existence of a foreign substance on the reticle. By this constitution, the defect due to the transfer of a foreign substance on the reticle will not be a mutual defect, and a highly reliable detection can be performed.

Description

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

In recent years, as the density of conductor integrated circuit devices has increased,
The method of forming fine patterns is becoming increasingly important. A recently developed reduction projection exposure apparatus as a means for forming this fine pattern has superior performance in terms of resolution and alignment accuracy compared to conventional apparatus.

However, since the fog light method is different from the conventional method and uses a fragment, step, pull and repeat method that repeatedly exposes each chip, if there is foreign matter such as dust on the reticle, all chips will be exposed using this method. The foreign matter is transferred and becomes a common defect, and depending on the size of the defect and its position within the chip, all Uni/S become defective.

Therefore, the most important issue when using a reduction projection exposure apparatus is to detect foreign substances on the mask with high reliability.

As a conventional method for detecting this, a method has been used in which a transferred wafer is inspected with the naked eye (comparison) using an optical microscope with a magnification of approximately several hundred times using a reduction projection exposure apparatus.

However, since this method relies on the naked eye for inspection, it is difficult to avoid inspection errors due to operator carelessness, and the reliability is extremely low. In addition, the inspection takes a long time,
Although it is possible to increase the reliability by repeating this inspection by a large number of workers, which has the drawback of requiring a large number of inspection man-hours, it is not sufficient and the number of inspection man-hours becomes enormous.

%, and in the case of large chips with very fine patterns, the two drawbacks of low reliability and an enormous number of inspection steps become even more pronounced.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an inspection method that can reliably detect foreign substances on a reticle and reduce the number of man-hours.

In this actual GI4, a reticle having the same plurality of chips 1 is used in a reduction projection exposure apparatus, and the plurality of chips are repeatedly applied to a non-transparent film formed on a transparent substrate. The present invention is characterized in that it includes a step of transferring, and a step of comparing and inspecting the first chip among the plurality of transferred chips and another second chip.

In the present invention, when a plurality of foreign objects such as dust are present on a reticle having the same plurality of chips, the foreign object having the same shape as the foreign object on the first chip is completely identical to the foreign object in any other second chip. It is based on the principle that the probability of existing at a location is equal to zero.

According to the present invention, based on this principle, even if foreign matter is present,
When chips are transferred using the step-pull-and-repeat method, defects in the same shape and position caused by the transfer of foreign matter are regularly repeated every few chips, depending on the number of chips in the reticle. This means that defects of the same shape that are repeated at the same location on all chips, so-called common defects, will not occur.

Therefore, even if there is a foreign object on the reticle, it is possible to separate the first chip, which has a defect of any shape at any position, and the second chip, which does not have a defect of the same shape at the same position. These first and second h.

By comparatively inspecting the two samples, it is possible to detect a difference between the two and detect the presence of a defect.

Furthermore, since the comparative inspection method of the present invention forms a non-transparent defect pattern on a transparent substrate and irradiates it with light, sufficient contrast can be obtained, and this light cannot be irradiated without human intervention. Since the increase/decrease is converted into an electrical signal and automatically compared and inspected, high reliability and reduced man-hours can be achieved.

Next, in order to better understand the characteristics of the present invention, an embodiment of the present invention will be described using FIG. WJ.

1 to 6 are main process diagrams in one embodiment of the present invention.

First, as shown in FIG. 1, a reticle 10 having two chips 101 and 102 as an example of multiple identical chips is shown.
Prepare 3. On this reticle 103 there is a foreign object 104,
105 and a circuit pattern 106. Chips 101 and 102 of these foreign substances 104 and 105, respectively.
It is clear that the deweighting is equal to zero when the position and shape are exactly the same at the same time. [1108t- to form] glass plate 1
07 indicates transparency to light, such as sapphire, soda lime, and quartz glass. The non-transparent film 108 is used to increase the contrast of the transferred pattern as will be described later, and is made of metal such as aluminum, and has a thickness of approximately 1 μm. Further, a photoresist 109 having a thickness of about 1 μm is applied to the upper surface of the non-transparent film 108. This photoresist 109 may be any commercially available photoresist, but it is desirable that it has few pinholes and has excellent resolution. Next, the reticle 103 shown in FIG. 1 is set at a predetermined location in the reduction projection exposure apparatus, and after exposing the photoresist 109 on the glass plate 107 shown in FIG. , foreign matter 104, 10 on the reticle 103
5 and circuit pattern 106 are transferred to form a photoresist image 110 (FIG. 3). After removing the non-transparent film 108 as a mask for etching the photoresist, the upper photoresist@
When 110 is removed, an impermeable capsular layer 111 is formed as shown in FIG.

FIG. 5 is a partial plan view of the non-permeable coating @111. 112 and 113 are respectively % of chip l0L102
114, 115, 116 are foreign substances 104, 10, respectively
5 and the transfer image of the circuit pattern 106, when the transfer *1- is formed by the method described above, the transfer image of the circuit pattern 111
Although it appears on all 16Fi chips, foreign matter transfer image 114,
The glass plate 104 shown in FIG. 4, which will appear only every two chips, is placed on the holder 111 as shown in FIG. Anti-chip lens 1 on the top of 113
Place 19.

After that, the light 120 through the objective lenses 118, 119t''
is irradiated onto the glass plate 107 to form transferred images 114°, 115.
The light passing through the area other than 116 (FIG. 5) is received by the 7-meters 121 and 122 (thus, converted into two electrical signals. Here, the transparent glass plate 107
In contrast, the transferred images 114°, 115, and 116 are non-transparent, so that sufficient contrast can be obtained for electrical signals. These two signals enter a differential amplifier 125 via amplifiers 123 and 124, respectively, where the signals are compared and delivered to an output 126.

If there is no pattern difference between the chips 112 and 113, that is, there is no defect, no signal is generated from the differential amplifier 125 at the output 126, but if there is a difference, that is, there is a defect. In the case: a difference occurs between the two signals, and after this is compared in the differential amplifier 125, a signal can be generated to detect the presence of a defect.

Next, by performing this comparative inspection while moving the holder 1171 in the lateral direction within the plane of the paper and in the direction perpendicular to the plane of the paper, it is possible to detect the presence of defects in the entire structure within the chip, that is, the presence of foreign objects on the reticle. can.

As described above, according to the present invention, by first using a reticle having a plurality of identical chips in a reduction projection exposure apparatus, defects that occur as a result of foreign matter on the reticle being transferred do not become common defects; Comparative inspection becomes possible.

Next, this reticle is transferred to a non-transparent coating on a transparent substrate to obtain sufficient contrast for irradiation with light, and the increase and decrease of this light is converted into electrical signals for comparative inspection. Ninth, test errors often seen in conventional intraocular tests can be prevented and highly reliable detection can be performed. Furthermore, by automating the inspection process, it is possible to reduce the number of man-hours.

[Brief explanation of drawings]

1 to 6 are main process diagrams in one embodiment of the present invention. In the figure, 101... Chip, 102... Chip, 103... Reticle, 104... Foreign matter on reticle, 105... - Foreign matter on reticle, 106...Circuit pattern on reticle, 10
7...Transparent glass plate, 108...
... Non-transparent film, 109 ... Photoresist, 110 ... Photoresist image, 111.
. . . Non-transparent coating, 112 . . . Transfer image of chip 101, 113 . . . Transfer image of chip 102, 114 . . . Foreign matter on reticle 1040
Transferred image, 115... Foreign matter on reticle 1050
Transfer image, 116...Transfer image of circuit pattern on reticle, 117...-Holder, 118...
...Objective lens, 119...Objective lens, 1
20...mark/light, 121...photomaru, i2
2... Photomal% 123... Amplifier, 124... Amplifier, 125... Differential amplifier, 126... Output. . 107 Written amendment to Kazusu Ward procedure (voluntary) 57, 9.2B Showa year, month, day, r'. Commissioner of the Japan Patent Office 1, Indication of the case 1981 Patent Application No. 1113
No. 92 No. 2, Title of invention: Pattern defect inspection method 3,
Person making the amendment Relationship to the case Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent 6 Contents of amendment (Patent application 111392-1982) (1) The scope of claims in the specification will be corrected as shown in the attached sheet. 7 Attachment: Attachment: 1 copy of the amended claims: “A reduction projection achromatic device characterized by using a reticle having a plurality of identical chips and including a step of ticking the plurality of chips.” Pattern defect inspection method.”

Claims (1)

[Claims] A step of repeatedly transferring the plurality of chips onto a non-transparent coating formed on a transparent substrate using a reticle having the same plurality of chips in a reduction projection exposure apparatus; , a step of comparing and inspecting the first chip among the plurality of transferred chips and another second chip;
A pattern defect inspection method characterized by comprising: