阅读说明：本技术 一种在线检测硅槽刻蚀深度的方法 (Method for detecting silicon groove etching depth on line ) 是由 李冰 李营营 于 2021-08-04 设计创作，主要内容包括：本发明涉及半导体制造技术领域,提出一种在线检测硅槽刻蚀深度的方法,包括在样品晶圆和待测晶圆的掺杂区域上构造监控结构,其中所述监控结构具有参考结构和多个对照结构,所述参考结构上不具有硅槽,所述多个对照结构上分别具有多个大小一致但数量不等的硅槽；利用所述样品晶圆上的监控结构确定硅槽刻蚀深度与硅槽电阻之间的相关关系；通过在线测试利用所述待测晶圆上的监控结构测量所述待测晶圆上的硅槽电阻；以及根据所述待测晶圆上的硅槽电阻以及所述相关关系确定所述待测晶圆上的硅槽刻蚀深度。(The invention relates to the technical field of semiconductor manufacturing, and provides a method for detecting the etching depth of a silicon groove on line, which comprises the steps of constructing a monitoring structure on a sample wafer and a doped region of a wafer to be detected, wherein the monitoring structure is provided with a reference structure and a plurality of comparison structures, the reference structure is not provided with the silicon groove, and the comparison structures are respectively provided with a plurality of silicon grooves with the same size but different numbers; determining the correlation between the etching depth of the silicon groove and the resistance of the silicon groove by using the monitoring structure on the sample wafer; measuring the silicon groove resistance on the wafer to be tested by using a monitoring structure on the wafer to be tested through online testing; and determining the etching depth of the silicon groove on the wafer to be tested according to the silicon groove resistance on the wafer to be tested and the correlation.)

1. A method for detecting the etching depth of a silicon groove on line is characterized in that the method comprises the following steps:

constructing a monitoring structure on the doped regions of the sample wafer and the wafer to be detected, wherein the monitoring structure is provided with a reference structure and a plurality of comparison structures, the reference structure is not provided with silicon grooves, and the comparison structures are respectively provided with a plurality of silicon grooves with the same size but different numbers;

determining the correlation between the etching depth of the silicon groove and the resistance of the silicon groove by using the monitoring structure on the sample wafer;

measuring the silicon groove resistance on the wafer to be tested by using a monitoring structure on the wafer to be tested through online testing; and

and determining the etching depth of the silicon groove on the wafer to be tested according to the silicon groove resistance on the wafer to be tested and the correlation.

2. The method of claim 1, wherein the step of determining the correlation between the etching depth of the silicon trench and the resistance of the silicon trench by using the monitoring structure on the sample wafer comprises the following steps:

measuring a resistance value of a monitoring structure on the sample wafer and determining a silicon trench resistance on the sample wafer by linear fitting;

measuring the etching depth of the silicon groove on the sample wafer by slicing the sample wafer; and

and determining the correlation between the silicon groove etching depth and the silicon groove resistance according to the silicon groove resistance on the sample wafer and the silicon groove etching depth on the sample wafer.

3. The method of claim 2, wherein measuring the resistance of the monitoring structure on the sample wafer and determining the resistance of the silicon trench on the sample wafer by linear fitting comprises:

measuring a resistance value of a first reference structure of a first monitoring structure on the sample wafer;

measuring resistance values of a plurality of first control structures of the first monitoring structure;

determining first linear fitting parameters, the first linear fitting parameters comprising:

a resistance value of the first reference structure and a number of silicon trenches on the first reference structure; and

resistance values of the plurality of first control structures and the number of silicon grooves on the plurality of first control structures; and

and performing linear fitting according to the first linear fitting parameters to determine the silicon groove resistance on the sample wafer.

4. The method for detecting the etching depth of the silicon trench in an online manner as claimed in claim 2, wherein: and slicing the sample wafer, and measuring the etching depth of the silicon groove on the sample wafer by acquiring data through a scanning electron microscope.

5. The method for on-line detection of silicon trench etching depth as claimed in one of claims 1 to 4, wherein the correlation between the silicon trench etching depth and the silicon trench resistance comprises a direct ratio.

6. The method for detecting the etching depth of the silicon trench in the on-line manner as claimed in claim 1, wherein: measuring the resistance value of the monitoring structure on the wafer to be tested through online test and determining the silicon slot resistance on the wafer to be tested through linear fitting, wherein the method comprises the following steps:

measuring the resistance value of a second reference structure of a second monitoring structure on the wafer to be tested through online testing;

measuring resistance values of a plurality of second control structures of the second monitoring structure;

determining second linear fitting parameters, the second linear fitting parameters comprising:

a resistance value of the second reference structure and a number of silicon trenches on the second reference structure; and

resistance values of the plurality of second control structures and the number of silicon grooves on the plurality of second control structures; and

and performing linear fitting according to the second linear fitting parameter to determine the silicon groove resistance on the wafer to be tested.

7. The method of claim 6, wherein the in-line testing comprises an in-line wafer acceptance test.

8. The method of claim 6, wherein the in-line test comprises an in-line chip probing test.

9. The method as claimed in any one of claims 6 to 8, wherein the resistances of a plurality of monitoring structures on the wafer to be tested are measured by an online test to calculate the resistances of the silicon trenches at different positions on the whole wafer to be tested.

10. The method for detecting the etching depth of the silicon trench in the on-line manner as claimed in claim 9, wherein: and substituting the silicon groove resistances at different positions on the whole wafer to be tested into the correlation to determine the silicon groove etching depths of the whole wafer to be tested at different positions, and generating a silicon groove etching depth distribution diagram of the wafer to be tested.

Technical Field

The present invention relates generally to the field of semiconductor manufacturing. Specifically, the invention relates to a method for detecting the etching depth of a silicon groove on line.

Background

Etching is an important process step in semiconductor manufacturing processes, which can transfer a pattern from a photoresist to a substrate wafer by means of chemical etching or plasma bombardment, for example. For etching silicon grooves, the etching depth of the silicon grooves and the etching uniformity of different areas on a wafer are important parameters for measuring the etching effect.

The prior art lacks an effective on-line measurement means, and the etching depth of the silicon trench can be measured only by slicing the wafer and then acquiring data by a Scanning Electron Microscope (SEM). However, the measurement method belongs to destructive measurement, and the wafer for slicing is damaged in the measurement process, and cannot be processed as a normal product piece any more, and only scrapped, so that the cost of the flow piece is increased. In addition, the measuring method can predict other product slices in the same batch only through the measurement of the sample slice, the monitoring effect is limited, and large errors exist particularly under the condition that the state of the etching equipment fluctuates. In addition, the measurement method needs manual operation in the processes of sample preparation, measurement and data analysis, so that the efficiency is low, a large amount of manpower and material resources are occupied, and resource waste and cost increase are caused.

Disclosure of Invention

In order to at least partially solve the above problems in the prior art, the present invention provides a method for detecting the etching depth of a silicon trench on line, wherein the detection is performed by a sample wafer and a wafer to be detected, the sample wafer and the wafer to be detected have a plurality of chips, and the plurality of chips have doped regions thereon, the method includes the following steps:

constructing a monitoring structure on the doped regions of the sample wafer and the wafer to be detected, wherein the monitoring structure is provided with a reference structure and a plurality of comparison structures, the reference structure is not provided with silicon grooves, and the comparison structures are respectively provided with a plurality of silicon grooves with the same size but different numbers;

determining the correlation between the etching depth of the silicon groove and the resistance of the silicon groove by using the monitoring structure on the sample wafer;

measuring the silicon groove resistance on the wafer to be tested by using a monitoring structure on the wafer to be tested through online testing; and

and determining the etching depth of the silicon groove on the wafer to be tested according to the silicon groove resistance on the wafer to be tested and the correlation.

In one embodiment of the present invention, it is provided that determining the correlation between the etching depth of the silicon trench and the resistance of the silicon trench using the monitoring structure on the sample wafer comprises the following steps:

measuring a resistance value of a monitoring structure on the sample wafer and determining a silicon trench resistance on the sample wafer by linear fitting;

measuring the etching depth of the silicon groove on the sample wafer by slicing the sample wafer; and

and determining the correlation between the silicon groove etching depth and the silicon groove resistance according to the silicon groove resistance on the sample wafer and the silicon groove etching depth on the sample wafer.

In one embodiment of the invention, it is provided that measuring the resistance value of the monitoring structure on the sample wafer and determining the silicon groove resistance on the sample wafer by linear fitting comprises the following steps:

measuring a resistance value of a first reference structure of a first monitoring structure on the sample wafer;

measuring resistance values of a plurality of first control structures of the first monitoring structure;

determining first linear fitting parameters, the first linear fitting parameters comprising:

a resistance value of the first reference structure and a number of silicon trenches on the first reference structure; and

resistance values of the plurality of first control structures and the number of silicon grooves on the plurality of first control structures; and

and performing linear fitting according to the first linear fitting parameters to determine the silicon groove resistance on the sample wafer.

In one embodiment of the invention, provision is made for: and slicing the sample wafer, and measuring the etching depth of the silicon groove on the sample wafer by acquiring data through a scanning electron microscope.

In one embodiment of the invention, the correlation between the etching depth of the silicon groove and the resistance of the silicon groove comprises a direct proportion relation.

In one embodiment of the invention, provision is made for: measuring the resistance value of the monitoring structure on the wafer to be tested through online test and determining the silicon slot resistance on the wafer to be tested through linear fitting, wherein the method comprises the following steps:

measuring the resistance value of a second reference structure of a second monitoring structure on the wafer to be tested through online testing;

measuring resistance values of a plurality of second control structures of the second monitoring structure;

determining second linear fitting parameters, the second linear fitting parameters comprising:

a resistance value of the second reference structure and a number of silicon trenches on the second reference structure; and

resistance values of the plurality of second control structures and the number of silicon grooves on the plurality of second control structures; and

and performing linear fitting according to the second linear fitting parameter to determine the silicon groove resistance on the wafer to be tested.

In one embodiment of the invention, it is provided that the online test comprises an online wafer acceptance test.

In one embodiment of the invention, it is provided that the in-line test comprises an in-line chip probing test.

In one embodiment of the invention, the resistances of a plurality of monitoring structures on the wafer to be tested are measured through online test so as to calculate the resistances of silicon slots at different positions on the whole wafer to be tested.

In one embodiment of the invention, provision is made for: and substituting the silicon groove resistances at different positions on the whole wafer to be tested into the correlation to determine the silicon groove etching depths of the whole wafer to be tested at different positions, and generating a silicon groove etching depth distribution diagram of the wafer to be tested.

The invention has at least the following beneficial effects: the etching depth of the silicon groove of the wafer to be tested can be measured in an online test mode, and the wafer to be tested cannot be damaged. Therefore, the silicon groove etching depth of any wafer to be measured can be obtained, and the silicon groove etching depth of other product wafers in the same batch can be predicted without measuring the sample wafer.

Drawings

To further clarify the advantages and features that may be present in various embodiments of the present invention, a more particular description of various embodiments of the invention will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings, the same or corresponding parts will be denoted by the same or similar reference numerals for clarity.

FIG. 1 shows a schematic diagram of a monitoring architecture in one embodiment of the invention.

FIG. 2 is a graphical representation of the results of a linear fit to the linear fit parameters of the monitored structure in one embodiment of the present invention.

FIG. 3 is a schematic diagram showing the correlation between the resistance of a silicon trench and the etching depth of the silicon trench in one embodiment of the present invention.

FIG. 4 shows a wafer silicon trench etch depth profile in an embodiment of the invention.

FIG. 5 is a flow chart showing the on-line detection of the etching depth of the silicon trench in one embodiment of the present invention.

Detailed Description

It should be noted that the components in the figures may be exaggerated and not necessarily to scale for illustrative purposes. In the figures, identical or functionally identical components are provided with the same reference symbols.

In the present invention, "disposed on …", "disposed over …" and "disposed over …" do not exclude the presence of an intermediate therebetween, unless otherwise specified. Further, "disposed on or above …" merely indicates the relative positional relationship between two components, and may also be converted to "disposed below or below …" and vice versa in certain cases, such as after reversing the product direction.

In the present invention, the embodiments are only intended to illustrate the aspects of the present invention, and should not be construed as limiting.

In the present invention, the terms "a" and "an" do not exclude the presence of a plurality of elements, unless otherwise specified.

In the present invention, the term "silicon trench resistance" refers to the amount of change in resistance value caused by a single silicon trench.

It is further noted herein that in embodiments of the present invention, only a portion of the components or assemblies may be shown for clarity and simplicity, but those of ordinary skill in the art will appreciate that, given the teachings of the present invention, required components or assemblies may be added as needed in a particular scenario. Furthermore, features from different embodiments of the invention may be combined with each other, unless otherwise indicated. For example, a feature of the second embodiment may be substituted for a corresponding or functionally equivalent or similar feature of the first embodiment, and the resulting embodiments are likewise within the scope of the disclosure or recitation of the present application.

It is also noted herein that, within the scope of the present invention, the terms "same", "equal", and the like do not mean that the two values are absolutely equal, but allow some reasonable error, that is, the terms also encompass "substantially the same", "substantially equal". By analogy, in the present invention, the terms "perpendicular", "parallel" and the like in the directions of the tables also cover the meanings of "substantially perpendicular", "substantially parallel".

The numbering of the steps of the methods of the present invention does not limit the order of execution of the steps of the methods. Unless specifically stated, the method steps may be performed in a different order.

The invention is further elucidated with reference to the drawings in conjunction with the detailed description.

A flowchart of an embodiment of the method for detecting the etching depth of the silicon trench on line according to the present invention can be shown in fig. 5.

The monitoring structure may first be built on a wafer (wafer). The sample wafer and the wafer to be tested are provided with a plurality of chips, wherein a monitoring structure is constructed on the doping area of each chip of the sample wafer and the wafer to be tested. The monitoring structure is provided with a reference structure and a plurality of comparison structures, the reference structure is not provided with silicon grooves, and the comparison structures are respectively provided with a plurality of silicon grooves with the same size but different numbers.

A schematic diagram of a monitoring architecture in one embodiment of the present invention is shown in fig. 1 a-d. Wherein, silicon grooves with the same size but different numbers are dug in the doped region of the wafer, so that different resistances of the doped region can be obtained. Fig. 1a-d show a schematic view of a set of monitoring structures. The structure shown in fig. 1a is a reference structure in which there are no etched regions. Fig. 1b includes an etched region formed by three silicon trenches, fig. 1c includes five silicon trenches, and fig. 1d includes seven silicon trenches. The structures shown in fig. 1b-d are comparative structures.

The monitoring structure on the sample wafer can be used for determining the correlation between the etching depth of the silicon groove and the resistance of the silicon groove, wherein the method comprises the following steps:

step one, measuring the resistance value of the monitoring structure on the sample wafer and determining the silicon groove resistance on the sample wafer through linear fitting, comprising the following steps:

measuring a resistance value of a first reference structure of a first monitoring structure on the sample wafer through an online test;

measuring resistance values of a plurality of first control structures of the first monitoring structure;

determining first linear fitting parameters, the first linear fitting parameters comprising:

a resistance value of the first reference structure and a number of silicon trenches on the first reference structure; and

resistance values of the plurality of first control structures and the number of silicon grooves on the plurality of first control structures; and

and performing linear fitting according to the first linear fitting parameters to determine the silicon groove resistance on the sample wafer.

Taking the monitoring structure in fig. 1a-d as an example, the total amount of impurities will be different due to different numbers of silicon trenches in the doped region of different comparison structures, and the difference of the total amount of impurities will be reflected by the measured resistance value. The results of linear fitting with the resistance values corresponding to the different structures in fig. 1a-b and the number of silicon trenches as parameters are shown in fig. 2. The abscissa 0-7 in fig. 2 corresponds to the number of silicon trenches shown as a-b in fig. 1, respectively. By the above-described linear fitting, the amount of change in the resistance value due to each silicon trench, that is, the silicon trench resistance can be determined.

And step two, measuring the etching depth of the silicon groove on the sample wafer by slicing the sample wafer, wherein the wafer can be sliced, and the etching depth of the silicon groove is measured by a method of acquiring data by a Scanning Electron Microscope (SEM).

And step three, determining the correlation between the silicon groove etching depth and the silicon groove resistance according to the silicon groove resistance on the sample wafer and the silicon groove etching depth on the sample wafer. The established correlation may be, for example, a correspondence table or a correspondence expression. In an embodiment of the present invention, the plurality of chips on the sample wafer are measured by the above method, and a relationship curve of a correlation between the silicon trench resistance and the silicon trench etching depth of the wafer, which can be obtained according to the test results of the plurality of chips, is shown in fig. 3, where the silicon trench resistance and the silicon trench etching depth are in a direct ratio.

And then measuring the silicon groove resistance on the wafer to be measured by using the monitoring structure on the wafer to be measured through online test.

The online Test used may be, for example, an online WAT Test (Wafer Acceptance Test) or an online CP (Chip Probing) Test.

And measuring the silicon groove resistance on the wafer to be measured by using the monitoring structure on the wafer to be measured. In a similar manner to measuring the resistance of the silicon trenches on the sample wafer, for example, the following steps may be included:

measuring the resistance value of a second reference structure of a second monitoring structure on the wafer to be tested through online testing;

measuring resistance values of a plurality of second control structures of the second monitoring structure;

determining second linear fitting parameters, the second linear fitting parameters comprising:

a resistance value of the second reference structure and a number of silicon trenches on the second reference structure; and

resistance values of the plurality of second control structures and the number of silicon grooves on the plurality of second control structures; and

and performing linear fitting according to the second linear fitting parameter to determine the silicon groove resistance on the wafer to be tested.

In the process of the online test, the resistances of the monitoring structures on the wafer to be tested can be measured through the online test, so that the resistance of the silicon slot on the whole wafer to be tested can be measured.

Therefore, the silicon groove etching depth of the whole wafer to be detected can be determined by substituting the silicon groove resistance of the whole wafer to be detected into the correlation, and a silicon groove etching depth distribution diagram of the wafer to be detected can be generated, as shown in fig. 4.

The flow chart of the method for detecting the etching depth of the silicon trench on line provided by the invention can be shown as fig. 5.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various combinations, modifications, and changes can be made thereto without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention disclosed herein should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.