CN110112079B - Method for evaluating etching process parameters of step sample block - Google Patents
Method for evaluating etching process parameters of step sample block Download PDFInfo
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- CN110112079B CN110112079B CN201910353879.0A CN201910353879A CN110112079B CN 110112079 B CN110112079 B CN 110112079B CN 201910353879 A CN201910353879 A CN 201910353879A CN 110112079 B CN110112079 B CN 110112079B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
Abstract
The invention provides an etching process parameter evaluation method of a step sample block, belonging to the technical field of semiconductor device testing and comprising the steps of calculating the height d of the step sample block; calculating the outer dimension a and the inner dimension b of the step sample block; calculating the side surface inclination angle theta of the step sample block; and setting a parameter epsilon to evaluate the etching process level, and calculating the parameter epsilon by using a relational expression of the parameter and the side face inclination angle of the step. The method for evaluating the etching process parameters of the step sample block can accurately measure the height and the inner and outer sizes of the step sample block, further determine the side surface inclination angle of the step sample block and accurately evaluate the etching process level of the step sample block.
Description
Technical Field
The invention belongs to the technical field of semiconductor device testing, and particularly relates to an etching process parameter evaluation method for a step sample block.
Background
In the field of integrated circuit and MEMS process manufacturing, there are a large number of geometric process parameters, wherein the step parameters directly affect the performance of the entire semiconductor device. Therefore, ensuring the measurement accuracy of the step structure plays an important role in reducing the characteristic parameters of the semiconductor device. At present, the main methods for measuring the steps are contact measurement and non-contact measurement. The contact type measurement precision is high, the measurement range is small, and the step surface scratch is easily caused. In a semiconductor process line, a step profiler is widely applied to step measurement as a main instrument of a contact type measurement method.
In order to ensure the accuracy of the step measuring instrument, the metering mechanism at home and abroad adopts a step height standard sample block to calibrate the instrument. A semiconductor etching process is generally used to develop a step height standard block. The step sample block presents a trapezoidal structure through scanning images, and in the process of sample block development, due to the limitation of an etching process, although the height size of the step can be accurately controlled, the side face of the step cannot be guaranteed to be completely and vertically etched, and the accuracy of the sample block is further influenced.
Disclosure of Invention
The invention aims to provide a method for evaluating etching process parameters of a step sample block, which can solve the technical problem of poor etching accuracy of the step sample block in the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that: the method for evaluating the etching process parameters of the step sample block comprises the following steps:
calculating the height d of the step sample block;
calculating the outer dimension a and the inner dimension b of the step sample block;
calculating the side surface inclination angle theta of the step sample block;
setting a parameter epsilon to evaluate the etching process level, wherein the relation between the parameter and the side face inclination angle of the step is as shown in a formula (1);
ε＝sinθ (1)。
further, the calculating the height of the step is performed by:
scanning out a step profile, dividing a step sample block into A, B areas and C areas as measurement calculation areas, measuring by adopting 1/3 of the width of each measurement calculation area, and obtaining a calculation result by a method of algebraic and average values of all-area equal weights of the three measurement calculation areas, wherein the calculation formula is shown as (2):
in the formula:
d-step height, unit: nm;
Ai-Z-axis displacement measurements in region a, in units: nm;
Bi-Z-axis displacement measurement in region B, in units: nm;
Ci-Z-axis displacement measurement in region C, in units: nm;
m is the number of measurement points of the area B;
n-region A, C measures points;
w is the width of the step.
Further, the calculating the outer dimension a and the inner dimension b of the step sample block comprises:
collecting a step sample block image, dividing the step sample block image into L, M, N, D, E five regions, and obtaining the whole pixel position of each region boundary through edge detection;
searching a starting point and a stopping point of the whole pixel position of the boundary;
obtaining sub-pixel positions by using an axial neighborhood sum-difference algorithm, and further obtaining the accurate position of a boundary;
and finishing the detection of the boundary position, and calculating the outer size a and the inner size b of the step sample block.
Further, the side surface inclination angle theta of the step sample block is obtained by calculation, and the calculation formula is shown as (3)
In the formula:
theta-side inclination angle of step sample block, unit: rad;
d is the height of the step sample block, unit: nm;
a-the outer dimension of the step sample block, unit: nm;
b-inner dimension of step sample block, unit: and (5) nm.
Further, the step sample block image is obtained using SEM acquisition.
Further, the height of the step sample block is obtained through scanning of a probe of the step meter.
The method for evaluating the etching process parameters of the step sample block has the beneficial effects that: and evaluating the etching process level by calculating the side surface inclination angle of the step sample block. Firstly, calculating the height of a step sample block; secondly, calculating the inner and outer sizes of the step sample block; then, calculating the side face inclination angle of the step sample block according to the height and the inner and outer sizes of the step sample block, and finally, setting a parameter related to the side face inclination angle to evaluate the level of the etching process. The process parameters are visual and simple and are easy to obtain, and the verticality and the etching process level of the side face of the sample block can be accurately and objectively reflected.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic perspective view of a step sample block according to an embodiment of the present invention;
fig. 2 is a schematic plan structure diagram of a step sample block according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of calculating the height of a step sample block according to an embodiment of the present invention;
FIG. 4 is a step sample image collected according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of an axial neighborhood sum-difference algorithm provided by an embodiment of the present invention;
FIG. 6 is a flow chart of an axial neighborhood sum-difference algorithm provided by an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1 and fig. 2, a method for evaluating etching process parameters of a step sample block according to the present invention will now be described. The method for evaluating the etching process parameters of the step sample block comprises the steps of calculating the height d of the step sample block;
calculating the outer dimension a and the inner dimension b of the step sample block;
calculating the side surface inclination angle theta of the step sample block;
setting a parameter epsilon to evaluate the etching process level, wherein the relation between the parameter and the side face inclination angle of the step is as shown in a formula (1);
ε＝sinθ (1)。
the invention provides a method for evaluating etching process parameters of a step sample block, which comprises the following steps of firstly, calculating the height of the step sample block; secondly, calculating the inner and outer sizes of the step sample block; then, calculating the side face inclination angle of the step sample block according to the height and the inner and outer sizes of the step sample block, and finally, setting a parameter related to the side face inclination angle to evaluate the level of the etching process.
According to the formula (1), when the parameter epsilon tends to 1, the side face inclination angle of the step sample block is close to 90 degrees, and the etching effect is better. Conversely, a smaller parameter epsilon indicates a poorer etching effect. The process parameters are visual and simple and are easy to obtain, and the verticality and the etching process level of the side face of the sample block can be accurately and objectively reflected.
Referring to fig. 3, as a specific embodiment of the method for evaluating the etching process parameters of the step sample block provided by the present invention, the step height is calculated by:
scanning out a step profile, dividing a step sample block into A, B areas and C areas as measurement calculation areas, measuring by adopting 1/3 of the width of each measurement calculation area, and obtaining a calculation result by a method of algebraic and average values of all-area equal weights of the three measurement calculation areas, wherein the calculation formula is shown as (2):
in the formula:
d-step height, unit: nm;
Ai-Z-axis displacement measurements in region a, in units: nm;
Bi-Z-axis displacement measurement in region B, in units: nm;
Ci-Z-axis displacement measurement in region C, in units: nm;
m is the number of measurement points of the area B;
n-region A, C measures points;
w is the width of the step.
Referring to fig. 2, 4 and 6, as a specific embodiment of the method for evaluating the etching process parameters of the step sample block provided by the present invention, the calculating the outer dimension a and the inner dimension b of the step sample block includes:
collecting a step sample block image, dividing the step sample block image into L, M, N, D, E five regions, and obtaining the whole pixel position of each region boundary through edge detection;
searching a starting point and a stopping point of the whole pixel position of the boundary;
obtaining sub-pixel positions by using an axial neighborhood sum-difference algorithm, and further obtaining the accurate position of a boundary;
and finishing the detection of the boundary position, and calculating the outer size a and the inner size b of the step sample block.
In the invention, a represents the outer dimension of the step sample block, namely the width of the bottom side of the trapezoid structure, and b represents the inner dimension of the step sample block, namely the width of the top side of the trapezoid structure. And because the size of the step sample block is in the micro-nano magnitude, the SEM is used for collecting the step sample block image. As shown in fig. 4, the step patch image is divided into L, M, N, D, E five regions, where the edge threshold variation of regions L, M, E, and D is large, and the edge position is easily detected. In contrast, the edge threshold variation of the regions M and N, N and D is small, and the edge position is not easily detected. In order to improve the edge detection precision, the edge position of the step sample block is detected by adopting an axial neighborhood sum-difference method.
As shown in FIG. 5, taking the boundary between the regions L and M as an example, let the gray scale value of the region L be G1The gray scale value of the region M is G2The coordinate of the integer pixel of the boundary position is (i'e,j'e) And the actual edge point is at the pixel point coordinate (i'e,j'e) Position of left u, and | u +<1, i.e. less than the size of one pixel. Wherein, the p-order axial neighborhood sum difference is shown in formula (4).
Calculating the sum and difference of the first three-order axial neighborhoods of the edge points by a formula (4), and further calculating u and G1、G2The sub-pixel edge position is obtained.
As a specific implementation mode of the method for evaluating the etching process parameters of the step sample block, the side surface inclination angle theta of the step sample block is obtained by calculation, and the calculation formula is shown as (3)
In the formula:
theta-side inclination angle of step sample block, unit: rad;
d is the height of the step sample block, unit: nm;
a-the outer dimension of the step sample block, unit: nm;
b-inner dimension of step sample block, unit: and (5) nm.
As a specific implementation mode of the method for evaluating the etching process parameters of the step sample block, the step sample block image is acquired by using a Scanning Electron Microscope (SEM).
As a specific implementation mode of the method for evaluating the etching process parameters of the step sample block, the height of the step sample block is obtained by scanning a probe of a step instrument.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. The method for evaluating the etching process parameters of the step sample block is characterized by comprising the following steps of:
calculating the height d of the step sample block;
calculating the outer dimension a and the inner dimension b of the step sample block;
calculating the side surface inclination angle theta of the step sample block;
setting a parameter epsilon to evaluate the etching process level, wherein the relation between the parameter and the side face inclination angle of the step is as shown in a formula (1);
ε＝sinθ (1)；
the height of the calculation step is calculated by:
scanning out a step profile, dividing a step sample block into A, B areas and C areas as measurement calculation areas, measuring by adopting 1/3 of the width of each measurement calculation area, and obtaining a calculation result by a method of algebraic and average values of all-area equal weights of the three measurement calculation areas, wherein the calculation formula is shown as (2):
in the formula:
d-step height, unit: nm;
Ai-Z-axis displacement measurements in region a, in units: nm;
Bi-Z-axis displacement measurement in region B, in units: nm;
Ci-Z-axis displacement measurement in region C, in units: nm;
m is the number of measurement points of the area B;
n-region A, C measures points;
w is the width of the step;
the step sample block outer dimension a and inner dimension b calculation includes:
collecting a step sample block image, dividing the step sample block image into L, M, N, D, E five regions, and obtaining the whole pixel position of each region boundary through edge detection;
searching a starting point and a stopping point of the whole pixel position of the boundary;
obtaining sub-pixel positions by using an axial neighborhood sum-difference algorithm, and further obtaining the accurate position of a boundary;
and finishing the detection of the boundary position, and calculating the outer size a and the inner size b of the step sample block.
2. The method of claim 1, wherein the step sample block is etched by a predetermined etching process,
the side surface inclination angle theta of the step sample block is obtained by calculation, and the calculation formula is shown as (3)
In the formula:
theta-side inclination angle of step sample block, unit: rad;
d is the height of the step sample block, unit: nm;
a-the outer dimension of the step sample block, unit: nm;
b-inner dimension of step sample block, unit: and (5) nm.
3. The method of claim 1, wherein the step block image is obtained using SEM acquisition.
4. The method for evaluating parameters of an etching process of a step sample block according to claim 1, wherein the height of the step sample block is obtained by scanning with a probe of a step profiler.
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| JP4477750B2 (en) * | 2000-06-26 | 2010-06-09 | 東京エレクトロン株式会社 | Etching method |
| WO2009154173A1 (en) * | 2008-06-17 | 2009-12-23 | 株式会社アルバック | Method for manufacturing multistep substrate |
| CN104101736A (en) * | 2014-08-11 | 2014-10-15 | 常州碳维纳米科技有限公司 | Preparation method for nanoscale step standard sample applied to calibration |
| CN105759080B (en) * | 2014-12-16 | 2019-04-12 | 中芯国际集成电路制造(上海)有限公司 | Step height regulation mould plate, its production method and calibration method |
| CN106556360A (en) * | 2015-09-24 | 2017-04-05 | 上海思信科学仪器有限公司 | A kind of step segment difference On-line Measuring Method |
| CN106017383B (en) * | 2016-06-22 | 2018-10-19 | 中国电子科技集团公司第十三研究所 | Contact step instrument probe in detecting figure sample block |
| CN107658314B (en) * | 2017-08-16 | 2020-04-24 | 长江存储科技有限责任公司 | Semiconductor device and method for manufacturing the same |
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