JPH0351747A - Pattern inspecting apparatus - Google Patents

Abstract

PURPOSE:To shorten the time of inspection by projecting a plurality of light beams at the same time, and obtaining detecting patterns for comparing design data and for comparing two chips. CONSTITUTION:The scanning of a stage 1 on which a mask 2 is set is controlled with a stage control system 11. When the positioning is completed, the pattern forming state of a part to be inspected is detected with the optical system comprising a lamp 3 and an inspecting lens 4 and a pattern detecting sensor 7. Design data are written in a magnetic disk 13, a tape 14 or a floppy disk 15. A CPU control part 16 reads said data and sends the data into a data comparing circuit 12. In the circuit 12, the inspection data from the control part 16 and the inspection data from the sensor 7 are compared and judged. The result is stored in a defect data memory 20. The result of the pattern comparing inspections with the optical system comprising the lamp 3, lenses 5 and 6 and sensors 8 and 9 is sent into a minute-defect detecting part 17. The data are compared in a right-and-left image comparing circuit 18. When the images are equal, it is judged that there is no defect with a minute-defect detecting circuit 19. The inspection time can be shortened by processing the comparing inspections of the design data and the pattern at the same time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a technique for inspecting the formation state of patterns of reticles, masks, etc., and is particularly effective when used for visual inspection using a combination of design data comparison inspection and pattern comparison inspection. It is about a certain technology.

[Conventional technology]

Ideally, the pattern formed on a mask or reticle should be faithfully drawn according to the design data, but due to malfunctions in the drawing equipment, material defects, defects that occur during the process, etc. It may not be possible to pass the street. If such a defect occurs, it will have an adverse effect on the element configuration of an LSI (Large Scale Integrated Circuit), leading to a decrease in yield and reliability. For this reason, shape/defect inspection has become the most important inspection.

Techniques related to such visual inspections were developed, for example, in 1983.
It is described on pages 159 to 167 of "Electronic Materials Separate Volume, Ultra-LSI Manufacturing and Testing Equipment Guidebook," published by Kogyo Chosenkai Co., Ltd., December 10, 2015.

By the way, the present inventor has studied defects in appearance inspection of masks and the like.

The following are the techniques studied by the present inventor, and the outline thereof is as follows.

That is, there are mainly two types of defect inspection apparatuses as follows.

(1) A design data comparison inspection method that directly compares the design data used to draw the mask pattern and the mask pattern.

(2) A pattern comparison inspection (two-chip comparison inspection) method that compares chip patterns within a mask or between masks.

Currently, the above two methods are used for mask appearance inspection. In addition, for reticles, usually only (1) is inspected, but in the case of multi-patterns (two or more pieces of the same pattern data exist), the above (2) is also inspected.

[Problem to be solved by the invention]

However, the inventor of the present invention has found that when the above-mentioned two tests (design data comparison test method and pattern comparison test method) are performed, a large amount of time is required for the test.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a pattern inspection technique that allows design data comparison inspection and pattern comparison inspection to be performed simultaneously, thereby reducing inspection time.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, an optical system that simultaneously irradiates a plurality of lights onto an inspection target having a light-shielding pattern and generates reflected or transmitted light, and obtains a detection pattern for design data comparison from one of the reflected or transmitted lights. The first detection unit and the reflected light or transmitted light used for the design data comparison are different from each other.
a second detection unit that obtains a detection pattern for two-chip comparison from the first detection unit; a data comparison unit that compares the detection pattern obtained by the first detection unit with a reference pattern based on design data; A micro defect detection section is provided for detecting a micro defect by comparing the difference between two detection patterns obtained by the detection section.

[Effect]

According to the above-described means, the optical system and pattern detection system for design data comparison inspection and pattern comparison inspection are formed simultaneously, and data comparison and pattern comparison are performed independently and simultaneously. Therefore, there is no need to perform two inspections on one inspection object in two steps as in the past, and it is possible to shorten inspection time.

〔Example〕

FIG. 1 shows a pattern inspection apparatus according to the present invention. A mask 2 on which a chrome pattern is formed is set directly above the stage, and a lamp 3 serving as a light source is installed directly above the mask 2. The light emitted by the lamp 3 is split into spectra by an optical path forming means (not shown) into an inspection lens 4.5.6 disposed on the mask 2. Here, the inspection lens 4 is used for data comparison inspection, and the inspection lenses 5 and 6 are used for pattern comparison inspection. Lamp 3 and inspection lens 4゜5.6
A combination of these forms an optical system.

Note that the light emitted from the inspection lenses 4, 5.6 passes through the mask 2.
In some cases, the inspection is carried out by transmitting the light, and in some cases, the inspection is carried out by detecting the light reflected from the mask 2. Here, the reflected light from the mask 2 is used, and the reflected light is passed through the inspection lens 4.5.6 again to the pattern detection sensor 7 (first detection section) using an image sensor such as a COD (charge coupled device). ), 8 and 9 (second detection unit).

For this purpose, the pattern image passed through the inspection lens 4.5.6 needs to be accurately imaged on the pattern detection sensor 7.8.9, and the image forming means is equipped with an autofocus control system. 10 are provided. This autofocus control system 10 is similar to an autofocus mechanism of a camera or the like.

The stage 1 needs to be able to move freely in the X-Y directions in order to place the mask 2 to be inspected into the optical system. A stage control system 11 is provided to perform this movement control.

The pattern detection sensor 7 is connected to a data comparison circuit 12 (data comparison section) that compares the detection signal with design data. This data comparison circuit 12 includes a CPU control unit 16 for reading data from a magnetic disk device 13, a magnetic tape 14, or a floppy disk 15, which are data supply means, and outputting the data to the data comparison circuit 12.
is connected.

On the other hand, the pattern detection sensors 8 and 9 include a micro defect detection unit 17 that compares each detection pattern and determines a micro defect by detecting a difference between the patterns.
A left-right image comparison circuit 18 compares and refers to each chrome pattern detected in step 9, and a minute defect detection circuit 19 detects minute defects (adhesion of foreign matter, contact, disconnection, missing wire, etc.) based on the comparison results of the left-right image comparison circuit 18. It consists of

Further, a defect information memory 20 is connected to the data comparison circuit 12 and the minute defect detection section 17 for storing the comparison results and defect detection results output from each.

Next, the operation of the embodiment with the above configuration will be explained with reference to the flowchart of FIG.

During inspection, stage 1 with mask 2 set is
This is performed while scanning is controlled by the stage control system 11 in the −Y direction. When positioning is completed (step 21
．． 22), First, in the case of design data comparison inspection, lamp 3
A detection system comprising an optical system of the inspection lens 4 and the pattern detection sensor 7 detects the pattern formation state of the inspection target site. On the other hand, the design data is stored in advance in the magnetic disk device 13, magnetic tape 14 or floppy disk 1.
It is written in one of 5. The CPU control unit 16 that has read data from either of these converts it into test data and sends it to the data comparison circuit 12. The data comparison circuit 12 reads the inspection data given from the CPU control unit 16 and the inspection data output from the pattern detection sensor 7 (step 23), compares the two (step 24), and determines whether there is a difference between the two. Determine whether or not.

The determination is stored in the defect information memory 20 (step 25).

On the other hand, a pattern comparison inspection is performed in parallel with the design data comparison inspection.

In this case, an optical system including the lamp 3 and the inspection lens 5.6 and the pattern detection sensors 8 and 9 are used, and the detection results are sent to the minute defect detection section 17 (step 27).

The inspection lens 5.6 is located directly above the two adjacent chrome patterns. A left and right image comparison circuit 18 compares the detection patterns obtained through the inspection lenses 5 and 6 with each other.
If the two detection patterns are exactly the same, the minute defect detection circuit 19 determines that there is no defect, and if there is a difference, it determines that there is a defect. The determination result by this minute defect detection circuit 19 is stored in the defect information memory 20 (step 30).

Note that when it is determined that the inspection for one inspection target has been completed (step 26.30), it is determined whether or not the inspection for all chips of the mask 2 has been completed (step 31).

If all chips have not been tested yet, the process returns to step 22 and the above process is repeated.

As mentioned above, the design data comparison inspection and the pattern comparison inspection can be performed at the same time, so it is possible to perform the two inspections at the same time using the inspection time of either one of the two inspection methods (the longer one takes longer). I can do it. For example, conventionally,
It used to take 60 to 90 minutes for design data comparison inspection and 30 minutes for pattern comparison inspection, but according to the embodiment of the present invention,
Two tests can be completed in the time required for the design data comparison test, and the test can be shortened by at least the time required for the pattern comparison test.

Above, the invention made by the present inventor has been specifically explained based on Examples, but it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. stomach.

In the above explanation, the invention made by the present inventor was mainly applied to the visual inspection of a mask used for 1:1 isostatic light, which is the field of application of the invention.
The present invention is not limited to this, and can also be applied to, for example, the visual inspection of a reticle for 5:1 reduction exposure.

Furthermore, although the above description has been directed to visual inspection, it is also possible to use it for foreign matter inspection. Further, in the above embodiment, an example of an l stage is shown, but by making a plurality of stages and providing each of them with the illustrated optical system of the present invention, micro defect detection section 17, and micro defect detection circuit 19, a plurality of stages can be used. Since the objects to be inspected can be inspected simultaneously, it is possible to increase the number of inspections to be processed.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical ones are as follows.

That is, an optical system that simultaneously irradiates a plurality of lights onto an inspection target having a light-shielding pattern and generates reflected or transmitted light, and obtains a detection pattern for design data comparison from one of the reflected or transmitted lights. The first detection unit and the reflected light or transmitted light used for the design data comparison are different from each other.
a second detection unit that obtains a detection pattern for two-chip comparison from the first detection unit; a data comparison unit that compares the detection pattern obtained by the first detection unit with a reference pattern based on design data; Since it is equipped with a micro-defect detection section that detects micro-defects by comparing the differences between two detection patterns obtained by the detection section, design data comparison inspection and pattern comparison inspection can be processed simultaneously, making it possible to perform one inspection. The inspection time spent on the target can be significantly reduced.

FIG. 1 is a block diagram of an embodiment of a pattern inspection apparatus according to the present invention, and FIG. 2 is a flowchart showing the operation of this embodiment.

1... Stage, 2... Mask, 3... Lamp,
4.5.6...Inspection lens, 7,8°9...Pattern detection sensor, 10...Autofocus control system, 1
1... Stage control system, 12... Data comparison circuit,
13... Magnetic disk device, 15... Floppy disk, 16... CPU control section, 17... Minute defect detection section, 18... Left and right image comparison circuit, 19... Minute defect detection circuit, 20...Defect information memory.

Claims (1)

[Claims] 1. Comparison of design data from an optical system that simultaneously irradiates a plurality of lights onto an object to be inspected having a light-shielding pattern and generates reflected light or transmitted light, and one of the reflected light or transmitted light. a first detection unit that obtains a detection pattern for two-chip comparison from two different reflected lights or transmitted lights that are different from the reflected light or transmitted light used for the design data comparison;
A data comparison section that compares the detection pattern obtained by the first detection section with a reference pattern based on design data, and a data comparison section that compares the difference between the two detection patterns obtained by the second detection section and detects minute defects. 1. A pattern inspection device comprising: a minute defect detection section that detects. 2. The optical system is configured to include a plurality of inspection lenses that simultaneously irradiate light from a light source to different parts of the light shielding pattern depending on the application. Pattern inspection equipment.