JPH04129241A - Inspection device - Google Patents

Abstract

PURPOSE:To inspect a semiconductor device without being subject to the influence of the defect of an exposure device or the defect of a reticle by installing a simulator section preparing master image patterns color-coded from the quality of materials and thickness of each layer and a comparison checking section comparing and checking the master image patterns and the patterns of pellets displayed as the master image patterns. CONSTITUTION:When a defect inspection in the gate wiring process of a dynamic RAM is performed, the mask pattern data of each layer up to a gate wiring from the formation of a field are added in a simulator section 6 first, and the added data are stained by using a refractive index, etc., from the quality of materials and thickness of each layer. Master image patterns formed by the simulator section 6 are used as master patterns, and semiconductor pellets 8 on a semiconductor substrate 4 placed on a stage 3 and pattern images acquired by observing the pellets 8 by an optical system 2 and a camera 1 are compared and checked by employing a comparison checking section 7.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the number of structural defects (such as adhesion of dust) on a semiconductor substrate up to a certain step during the diffusion step of the manufacturing process of a semiconductor device. The present invention relates to a defect inspection device that inspects defects and their sizes.

[Conventional technology]

FIG. 2 is a diagram schematically showing an example of a conventional defect inspection apparatus. Conventionally, this type of defect inspection apparatus, as shown in FIG. 2, has a semiconductor device 4 mounted thereon, a stage 3 that moves in the an optical system 2 and a camera 1 for observing the whole, a memory section 9 for storing images obtained by observing the same part of two adjacent semiconductor pellets 8;
It has a comparison inspection section 10 that converts these two images into signals for each pixel and compares and inspects them, and a data expansion section 11 that stores the results of the comparison inspection.

Next, the operation of this defect inspection device will be explained. First, the semiconductor substrate 4 placed on the stage 3 is moved in the X and Y directions, and the optical system 2 and camera 1 take images of the same portion of two adjacent semiconductor pellets 8. Next, camera 1
The comparison inspection unit 10 compares the two images obtained by observing the signal level for each pixel of the camera 1, and determines the presence or absence of a defect and the size of the defect based on the difference and the spread of pixels with different signal levels. do. FIG. 3 is a diagram schematically showing another example of a conventional defect inspection device.

Further, as shown in FIG. 3, another defect inspection apparatus includes a stage 3 that moves the semiconductor substrate 4 in the X and Y directions, an optical system 2 and a camera for observing part or all of the semiconductor pellet 8. 1, an integration memory unit 12 for integrating and storing a plurality of images of the same portion of the same type of semiconductor pellet 8, and an inspection unit 13 for performing a comparative inspection between the detected image of the semiconductor pellet 8 and the accumulated image. There is something that consists of The inspection method of this device is to first move the semiconductor substrate 4 placed on the stage 3 in the X and Y directions, and then
At least 50 images are observed for the same part of the image using different pellets, and the images obtained each time are integrated, further averaged, and stored in the integration memory section 12. Using this averaged image as a master image, an image of the semiconductor pellet 8 to be inspected is captured, and a comparison inspection with the obtained image is performed.

In this inspection, the image of the actual semiconductor pellet 8 and the master image are compared pixel by pixel, and the presence or absence of a defect and its size are determined from the difference in signal level and the spread of pixels with different signal levels.

[Problem to be solved by the invention]

The defect inspection apparatuses described above have common problems. For example, the former type of defect inspection equipment performs inspection by comparatively inspecting adjacent pellets on a semiconductor substrate. If there is only one reticle pattern, and this pattern has a defect such as a foreign object, all the pellets to which the pattern has been transferred by this reticle will have the same defect, and this device will not be able to handle this type of defect. The problem is that it cannot be detected. However, since the reticle used in a reduction projection exposure system is engraved with patterns for multiple semiconductor bullets, the probability that a defect with the same shape will occur in the same location on each of the reticles is almost zero, so Comparative inspection of two pellets using a device can also be used. on the other hand,
Future large-scale integrated semiconductor devices, e.g. 10M
In a bit DRAM, the external dimensions are almost the same as the exposure area of a reduction projection exposure device (approximately 20+u×20 mm), making it impossible to inscribe a plurality of patterns for each reticle and expose them simultaneously. Furthermore, even now, it is not possible to perform defect inspection on large-sized items such as gate arrays of microcomputers as with this device. The same can be said for the latter device. However, in the case of the latter device, it is possible to create a master image by using a plurality of reticles and integrating images of the pellets on the semiconductor substrate exposed by each reticle. However, there is no ability to detect similar defects caused by foreign matter adhering to the optical system itself of the reduction projection exposure apparatus.An object of the present invention is to provide a defect inspection apparatus that solves this problem.

[Means to solve the problem]

The defect inspection apparatus of the present invention is a defect inspection apparatus that inspects the number and size of structural defects of a semiconductor substrate in a diffusion process in which an integrated circuit is fabricated by transferring various fine mask patterns onto a semiconductor substrate. , a memory section that stores and holds the mask pattern of each layer formed in the manufacturing process, and the mask pattern is superimposed according to the manufacturing process,
Consisting of a simulator section that creates a master image pattern by color-coding superimposed patterns based on the material and thickness of each layer, and a comparison inspection section that compares and inspects this master image pattern with the imaged pattern obtained from the semiconductor substrate. be done.

〔Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram schematically showing an embodiment of the defect inspection apparatus of the present invention. As shown in the figure, this defect inspection device has a memory section 5 that stores a plurality of patterns for each layer formed on a semiconductor substrate, and creates a master image pattern by overlapping the patterns in this memory section 5. The present invention is provided with a simulation section 6 for performing a comparison inspection with the pattern of the semiconductor pellet 8 and a master image pattern. Other than that, the camera 1, optical system 2, and stage 3 are the same as before.

For example, if such defect inspection equipment is used to inspect defects in the gate/wiring process of a dynamic RAM, first, in the simulator section, mask pattern data for each layer from field formation to gate wiring is superimposed,
This is then colored using the refractive index and the like based on the material and thickness of each layer. Next, using the mass image pattern generated by this simulator section 6 as a master pattern,
The semiconductor pellet 8 on the semiconductor substrate 4 placed on the stage 3 is observed by the optical system 2 and the camera 1, and a comparison inspection with a pattern image obtained is performed using the comparison inspection section 7. In addition, as a means of inspection, both images are converted into signals for each pixel,
The method of taking those strength mortar is effective.

On the other hand, it is possible to inspect a single layer mask pattern using the apparatus of this embodiment. That is, in this case, the semiconductor substrate 4 on which the pattern of the semiconductor device 8 has not yet been transferred is
A photoresist is applied to the surface, which is exposed and developed using a reticle in a certain process. By performing a comparative inspection of this semiconductor substrate 5 using the apparatus of the present invention using pattern information from the same process, it is possible to check whether there are defects due to foreign matter on the reticle or the like before actually working on the semiconductor substrate.

〔Effect of the invention〕

As explained above, the present invention includes a simulator unit that superimposes patterns in each layer to create a master image pattern that is color-coded based on the material and thickness of each layer, and a comparison unit that performs comparative inspection with the pellet pattern projected by the master image pattern. By providing an inspection department,
This has the effect of providing a defect inspection apparatus that can inspect defects in semiconductor devices without being affected by defects in the exposure apparatus or defects in the reticle.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of an embodiment of a defect inspection apparatus of the present invention, and FIGS. 2 and 3 are diagrams showing an outline of an example of a conventional defect inspection apparatus. 1...Camera, 2...Optical system, 3...Stage,
4... Semiconductor substrate, 5, 9... Memory section, 6...
Simulator section, 7, 10... Comparison inspection section, 8...
Semiconductor pellet, 11...Data expansion section, 12...
Integration memory section, 13...inspection section.

Claims (1)

[Claims] In a defect inspection device that inspects the number and size of structural defects on a semiconductor substrate during a diffusion process in which various fine mask patterns are transferred onto a semiconductor substrate to fabricate an integrated circuit, each layer formed during the manufacturing process is used. a simulator section that creates a master image pattern by superimposing the mask patterns according to the manufacturing process and color-coding the superimposed patterns based on the material and thickness of each layer, and the master image pattern. A defect inspection apparatus comprising: a comparison inspection section that compares and inspects the imaged pattern obtained from the semiconductor substrate.