CN-115979142-B - Ellipsometer-oriented light spot size measuring device and measuring method

CN115979142BCN 115979142 BCN115979142 BCN 115979142BCN-115979142-B

Abstract

The invention relates to an ellipsometer-oriented light spot size measuring device and a ellipsometer-oriented light spot size measuring method. The method comprises the steps of obtaining a light spot of an ellipsometer on a grating reflection assembly, obtaining a central position coordinate of the light spot, fitting a light spot gray value by using a Gaussian model, establishing a three-dimensional form of the light spot, obtaining a light spot gravity center position, establishing a detection coordinate system, obtaining a pattern central position of a square pattern, overlapping the pattern center with the light spot gravity center, measuring light spot size detection samples in a plurality of detection coordinate systems, establishing a detection thickness variation curve, intercepting a qualified measurement part in the detection thickness variation curve, obtaining the size of the qualified measurement part, wherein the size of the light spot of the ellipsometer is equal to the size of the square pattern minus the size of the qualified measurement part, and detecting the light spot size and form of the ellipsometer.

Inventors

JIANG PAN
CHEN JUN
HE YONG
YANG CHENG
LI WEIQI
GUO CHUNFU
ZHANG CHUANWEI

Assignees

武汉颐光科技有限公司

Dates

Publication Date: 20260508
Application Date: 20221213

Claims (6)

1. An ellipsometer-oriented spot size measuring device, comprising: a camera module for shooting the light spot form of the ellipsometer; a grating reflection assembly for reflecting ellipsometer light spots to cause light to enter the camera assembly; A spot size detection sample which is a SiO2 sample having a square pattern, and The sample displacement table is used for placing and adjusting the size of the light spot to detect the position of the sample; the camera module comprises a camera displacement table and a camera assembly formed by a camera lens and a CMOS sensor, wherein the camera displacement table is used for fixing the camera assembly and has a three-dimensional linear displacement adjusting function; The grating reflection assembly and the spot size detection sample are both positioned on the focal plane of the ellipsometer, and the gravity center position and the pattern center coincide in the vertical direction.
2. The measurement device of claim 1, wherein the grating reflection assembly has a periodic grating structure and a reflection angle of the grating reflection assembly to the spot is less than an acceptance angle of the camera assembly.
3. The measurement device of claim 1, wherein the difference between the thickness of the square pattern on the spot size detection sample and the thickness of the blank area is not less than 100nm.
4. An ellipsometer-oriented spot size measurement method, which is implemented based on the measurement device of any one of claims 1 to 3, and is characterized by comprising: The center of gravity of the light spot is obtained and is the actual intensity center of the light spot taking the light intensity into consideration; Acquiring the pattern center of the square pattern; Establishing a detection coordinate system by taking the gravity center position as an origin; acquiring detection thickness values of a plurality of positions in the detection coordinate system; acquiring the size of a qualified measurement part; the ellipsometer spot size is equal to the square pattern size minus the qualified measurement portion size; Acquiring the gravity center position of the light spot comprises the following steps: Controlling the camera displacement table to enable the camera component to image the focal plane of the ellipsometer; controlling the sample displacement table to enable the surface of the grating reflection assembly to be positioned on the focal plane of the ellipsometer; acquiring a light spot image on the grating reflection assembly by using the camera assembly, wherein the light spot image comprises light spots; acquiring the central position coordinates of the light spots in the light spot image; Establishing an image coordinate system according to the central position coordinate; Fitting gray values of the light spots on the light spot image by using a Gaussian model on the image coordinate system, wherein the Gaussian model fitting comprises denoising the light spot image; Establishing a three-dimensional form of the light spot on the light spot image; and acquiring the gravity center position of the light spot in the three-dimensional form by using a pre-established light spot gravity center model.
5. The measurement method according to claim 4, wherein acquiring the detected thickness values for a plurality of positions in the detected coordinate system comprises: And controlling the sample displacement table to move to a plurality of positions preset in the detection coordinate system respectively, measuring by using the ellipsometer to obtain detection thickness values of the plurality of positions in the detection coordinate system, and establishing a detection thickness change curve according to the detection thickness values in the detection coordinate system.
6. The measurement method according to claim 5, wherein obtaining the size of the qualified measurement portion comprises: And intercepting a qualified measurement part in the detection thickness variation curve according to a preset acceptable thickness error in the detection thickness variation curve.

Description

Ellipsometer-oriented light spot size measuring device and measuring method Technical Field The invention relates to the technical field of optical measurement, in particular to an ellipsometer-oriented light spot size measuring device and a ellipsometer-oriented light spot size measuring method. Background The ellipsometer is a precise instrument for measuring the optical constant and the film thickness of a micro-nano film based on optical polarization, and the basic principle is that the information such as the optical constant and the film thickness of a sample is inversely analyzed by measuring the change of the polarization state of the elliptical polarized light before and after reflection on the surface of the sample to be measured. Compared with other optical film measuring means, the ellipsometer is a self-reference measuring mode, has high spectral sensitivity, and is the most effective means for measuring the optical constant and the film thickness of the nano-scale film with high precision at present. In recent years, in nano-fabrication, particularly in large-scale semiconductor chip fabrication, chip fabrication is continuously advancing to smaller nano-scale in order to improve chip performance, reduce chip usage power consumption, reduce chip area, and improve chip yield. In order to ensure the accuracy of the semiconductor chip manufacturing, manufacturers of semiconductor chip manufacturing equipment need to advance with time, improve the measurement accuracy, expand the measurement spectrum range, and compress the measurement area size so as to meet the manufacturing process change brought by the chip manufacturing process. Ellipsometry is a key measurement device in semiconductor chip manufacturing, and the size and shape of the light spot irradiated on a sample determine the measurement capability of the device to a tiny area. In general, the ellipsometer has two evaluation aspects of the spot size and the form, namely, the ideal spot size and the form which are simulated by using simulation software when the ellipsometer is designed, and the minimum area size which can be measured in a reasonable precision range when the ellipsometer is actually put into use, and reflects the actual spot size and the form of the ellipsometer. However, the quality of the light beam and the assembly of the optical lens cannot maintain the ideal state in the actual production and manufacturing process of the device, and the size and the shape of the light spot reflected by the ellipsometer in actual use are far from ideal. Therefore, in the production and use of ellipsometers, it is a necessary step to detect the spot size and morphology of the device. Disclosure of Invention The invention provides a light spot size measuring device and a light spot size measuring method for an ellipsometer, which are used for solving the problem that the size and the shape of a light spot cannot be detected in time when equipment is produced and used so as to meet the manufacturing process change brought by the promotion of chip manufacturing processes. The technical scheme for solving the technical problems is as follows: In one aspect, the present invention provides an ellipsometer-oriented spot size measurement apparatus, including: a camera module for shooting the light spot form of the ellipsometer; a grating reflection assembly for reflecting ellipsometer light spots to cause light to enter the camera assembly; A spot size detection sample which is a SiO2 sample having a square pattern, and And the sample displacement table is used for placing and adjusting the size of the light spot to detect the position of the sample. Further, the camera module comprises a camera displacement table and a camera assembly formed by a camera lens and a CMOS sensor, wherein the camera displacement table is used for fixing the camera assembly and has a three-dimensional linear displacement adjusting function. Further, the grating reflection assembly has a periodic grating structure, and the angle of reflection of the light spot by the grating reflection assembly is smaller than the angle of reception of the camera assembly. Further, the difference between the thickness of the square pattern on the spot size detection sample and the thickness of the blank area is not less than 100nm. On the other hand, the invention also provides a method for measuring the size of the light spot facing the ellipsometer, which is realized by the measuring device and comprises the following steps: acquiring the gravity center position of the light spot; Acquiring the pattern center of the square pattern; Establishing a detection coordinate system by taking the gravity center position as an origin; acquiring detection thickness values of a plurality of positions in the detection coordinate system; acquiring the size of a qualified measurement part; the ellipsometer spot size is equal to the size of the square pattern minus the size of the qualified meas