CN112185839A - Passivation layer test structure - Google Patents

Abstract

The invention provides a passivation layer test structure. The passivation layer test structure includes: the structure layer comprises a plurality of conductive wires, and the conductive wires comprise at least one step-type structure; and passivation layers are formed on the surfaces of the substrate and the structural layer. According to the passivation layer test result provided by the invention, the stepped passivation layer test structure is provided, so that whether defects exist in a special position of the passivation layer, particularly in a corner area of the passivation layer is effectively detected, and the integrity of the passivation layer in a semiconductor device is checked. Compared with the existing passivation layer test structure, the test result of the passivation layer integrity test by adopting the passivation layer test structure provided by the invention has higher reliability.

Description

Passivation layer test structure

Technical Field

The invention relates to the technical field of semiconductors, in particular to a passivation layer test structure.

Background

Passivation of the chip surface has become one of the essential process steps for high performance and high reliability integrated circuits. The passivation layer is mainly used for electrically isolating the semiconductor devices and the wires from each other and isolating the semiconductor devices from the surrounding atmosphere, so as to enhance the blocking capability of the semiconductor devices against foreign ion contamination, protect the interconnections inside the semiconductor devices, and prevent the semiconductor devices from mechanical damage and chemical damage.

The kind and structure of the passivation layer have a great influence on the stress formed inside the interconnect line and the speed of the stress release. In the preparation process of an integrated circuit, the processes of deposition, polishing, photoetching and the like are accompanied by the change of temperature, and the internal stress of the passivation layer is changed in the process of the change of temperature, so that defects such as pinholes, cracks, falling off and the like are formed. The occurrence of such defects may cause deformation inside the chip and short or open circuit of the interconnection wires, thereby causing failure of the semiconductor device. In order to avoid this, it is necessary to perform integrity testing of the passivation layer on the semiconductor device to ensure that the semiconductor device can be used properly.

In order to check whether the passivation layer of the semiconductor device has the defect, the integrity test of the passivation layer is generally performed by using the passivation layer of an S-type (i.e., the structure shown in fig. 1), an interdigital type (i.e., the structure shown in fig. 2), or a ring type structure in the prior art. However, the S-shaped, interdigitated, or ring-shaped passivation layer test structure cannot accurately measure the integrity of the passivation layer having a specific structure (e.g., corner region) in the conventional process, and thus a new passivation layer test structure is required to better detect the integrity of the passivation layer.

Disclosure of Invention

The invention aims to provide a passivation layer test structure, which can effectively detect whether a special position of a passivation layer, particularly a corner region of the passivation layer has a defect or not by providing a step-type passivation layer test structure, thereby checking the integrity of the passivation layer in a semiconductor device.

In order to achieve the above object, the present invention provides a passivation layer test structure for testing integrity of a passivation layer, the passivation layer test structure comprising:

the structure layer comprises a plurality of conductive wires, and the conductive wires comprise at least one step-type structure; and passivation layers are formed on the surfaces of the substrate and the structural layer.

Optionally, the conductive wire includes a plurality of step structures arranged repeatedly in succession or a plurality of step structures arranged in a mirror image.

Optionally, the stepped structure includes a first bottom edge and a second bottom edge connected to each other, and the length of the first bottom edgeL₁Is greater than the length L of the second bottom edge₂。

Optionally, the length L of the first base edge₁And minimum design rule X₁Has a relationship of L₁≥5X₁。

Optionally, the length L of the second base line₂And minimum design rule X₂Has a relationship of X₂≤L₂≤3X₂。

Optionally, the included angle between the first bottom edge and the second bottom edge is 70-110 °.

Optionally, the number of the conductive wires is N, N is greater than or equal to 3 and less than or equal to 8, and the conductive wires are parallel to each other.

Optionally, the integrity test of the passivation layer is performed on the passivation layer test structure through an electrical test or a chemical test.

Optionally, the step of testing the electrical property includes: and forming a conductive material layer on the surface of the passivation layer, and judging whether the passivation layer is complete or not by detecting the resistance between the structural layer and the conductive material layer.

Optionally, in the chemical test, the passivation layer test structure is etched by using a chemical solution, and whether the passivation layer is complete or not is judged by observing the etched appearance of the passivation layer test structure.

In summary, the present invention provides a passivation layer testing structure for testing the integrity of a passivation layer. The passivation layer test structure includes: the structure layer comprises a plurality of conductive wires, and the conductive wires comprise at least one step-type structure; and passivation layers are formed on the surfaces of the substrate and the structural layer. According to the passivation layer test result provided by the invention, the stepped passivation layer test structure is provided, so that whether defects exist in a special position of the passivation layer, particularly in a corner area of the passivation layer is effectively detected, and the integrity of the passivation layer in a semiconductor device is checked. Compared with the existing passivation layer test structure, the test result of the passivation layer integrity test by adopting the passivation layer test structure provided by the invention has higher reliability.

Drawings

FIG. 1 is a schematic diagram of a defect structure of an S-type passivation layer test structure after chemical testing in the prior art;

FIG. 2 is a schematic diagram of a defect structure after a chemical test is performed on an interdigital passivation layer test structure in the prior art;

FIG. 3 is a top view of a passivation layer test structure according to an embodiment of the invention;

FIG. 4 is a cross-sectional view of the passivation layer test structure depicted in FIG. 3 along the OO' axis;

FIG. 5 is an enlarged view of a step-type structure in the passivation layer test structure illustrated in FIG. 3;

FIG. 6 is a schematic structural diagram of another passivation layer test structure according to an embodiment of the present invention;

FIG. 7 is a schematic view of a defect structure after chemical testing of the passivation layer test structure shown in FIG. 3;

wherein the reference numbers are as follows:

100-a substrate; 200-structural layer; 210. 210' -a conductive line; 211. 211' -a stepped structure;

300-passivation layer.

Detailed Description

The following describes in more detail embodiments of the present invention with reference to the schematic drawings. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Fig. 3 is a top view of a passivation layer test structure provided in the present embodiment, and fig. 4 is a cross-sectional view of the passivation layer test structure shown in fig. 3 along an OO' axis. As can be seen from fig. 3 and 4, the passivation layer test structure of the present embodiment includes asubstrate 100, astructural layer 200 is formed on at least a portion of a surface of thesubstrate 100, thestructural layer 200 includes a plurality ofconductive lines 210, and theconductive lines 210 include at least one step-type structure 211; apassivation layer 300 is formed on the surfaces of thesubstrate 100 and thestructural layer 200.

The passivation layer test structure provided in this embodiment is described in detail below with reference to fig. 3 to 7.

Referring first to fig. 3, theconductive lines 210 include A, B, C and D four conductive lines, and the conductive lines A, B, C and D are parallel to each other. In other embodiments of the present invention, the number of theconductive wires 210 may be plural, which is not limited by the present invention, and it is preferable that the number of theconductive wires 210 is between 3 and 8 in consideration of the test cost and the test accuracy. Fig. 5 is an enlarged view of astep type structure 211 in the passivation layer test structure illustrated in fig. 3. Referring to fig. 5, thestepped structure 211 includes a first bottom edge and a second bottom edge connected to each other, and a length L of the first bottom edge₁Is greater than the length L of the second bottom edge₂. Specifically, the length L of the first bottom edge₁And minimum design rule X₁Has a relationship of L₁≥5X₁. The length L of the second bottom edge₂And minimum design rule X₂Has a relationship of X₂≤L₂≤3X₂. In this embodiment, the minimum design rule X₁And X₂All are the minimum length units in the passivation layer test structure, and the minimum design rule X₁And X₂Are equal. In other embodiments of the present invention, the minimum design rule X₁And X₂May not be equal, and the invention is not limited in this regard. In this embodiment, the included angle between the first base line and the second base line is 90 °, and in other embodiments of the present invention, the included angle between the first base line and the second base line comprises 70 ° to 110 °.

Referring to fig. 3 and 6, a plurality ofstep structures 211 may be arranged on the conductive line in a mirror image manner or a plurality of step structures 211' may be arranged in a continuous and repeated manner. In this embodiment, thestructural layer 200 is made of a conductive material, including aluminum, copper or gold, and thestructural layer 200 may also be made of an alloy or other conductive materials, which is not limited in the present invention. Optionally, a functional region or other regions of the semiconductor device may be further included between thesubstrate 100 and thestructural layer 200, which is common knowledge of those skilled in the art and is not described herein.

The passivation layer test structure provided by the embodiment is used for testing the integrity of the passivation layer in the semiconductor device, and the integrity test of the passivation layer comprises an electrical test or a chemical test. It should be noted that there are various methods for testing the integrity of the passivation layer in the semiconductor device, and in other embodiments of the present invention, other passivation layer integrity test methods may be used to perform integrity test on the passivation layer test structure provided by the present invention.

The electrical property testing step comprises: a conductive material layer (not shown in the drawings) is formed on the surface of thepassivation layer 300, and whether thepassivation layer 300 is complete or not is determined by detecting the resistance between thestructural layer 200 and the conductive material layer. In this embodiment, the conductive material layer is formed on the surface of thepassivation layer 300 by a deposition process. When thepassivation layer 300 has defects such as pinholes, cracks, and the like, the defects expose a portion of thestructural layer 200, and therefore, in the process of depositing and forming the conductive material layer, the conductive material layer is deposited on the surface of thestructural layer 200 where the defects are exposed, resulting in the conductive material layer being in communication with thestructural layer 200, and the resistance between the conductive material layer and thestructural layer 200 is very low. When thepassivation layer 300 is not defective, the conductive material layer and thestructural layer 200 are separated by thepassivation layer 300, and the resistance between the conductive material layer and thestructural layer 200 is very high. Therefore, it is only necessary to measure the resistance between thestructural layer 200 and the conductive material layer to determine whether thepassivation layer 300 is complete. It should be noted that the specific method for electrical testing and the specific external circuit are both in the prior art, and the present invention will not be described in detail.

The chemical test uses a chemical solution to etch the passivation layer test structure, and whether thepassivation layer 300 is complete is judged by observing the etched appearance of the passivation layer test structure. Specifically, since the size of a part of defects in thepassivation layer 300 is too small to be directly observed, the passivation layer test structure needs to be processed by using a chemical solution. First, the passivation layer test structure is immersed in the passivation layer test structureA chemical solution entering thestructural layer 200 through defects in thepassivation layer 300, thestructural layer 200 forming an etch cavity under the etching of the chemical solution; and then, observing the passivation layer test structure by using an optical microscope, wherein the corrosion holes are black under the optical microscope, and thepassivation layer 300 is in a transparent state under the optical microscope, so that whether thepassivation layer 300 is complete or not can be judged by observing whether the corrosion holes appear in the passivation layer test structure or not. Alternatively, the chemical solution may be a potassium hydroxide (KOH) solution; phosphorous acid (H)₃PO₃) Nitric acid (HNO)₃) And acetaldehyde (CH)₃CHO); ammonium fluoride (NH)₄F) And acetaldehyde (CH)₃CHO); ammonium monohydrate (NH)₄OH), hydrogen peroxide (H)₂O₂) And Ultra Pure Water (UPW). In other embodiments of the present invention, the chemical solution may be other solutions having a corrosive effect, and the present invention is not limited thereto.

In order to verify the integrity test effect of the passivation layer test structure provided by this embodiment, a chemical test is performed on the passivation layer test structure provided by this embodiment. Fig. 7 is a schematic view of a defect structure of the passivation layer test structure after chemical testing. Referring to fig. 7, in the passivation layer test structure provided in this embodiment, defects (i.e., areas indicated by circles in fig. 7) are prone to occur on the inner sides of the corners of the two outermost conductive lines of the structure layer. Similarly, the S-type passivation layer test structure and the interdigital passivation layer test structure are chemically tested under the same test conditions, so as to obtain a defect structure schematic diagram of the S-type passivation layer test structure (i.e., fig. 1) and a defect structure schematic diagram of the interdigital passivation layer test structure (i.e., fig. 2). As can be seen by comparing fig. 1, 2 and 7, no significant defect is detected at a specific position of the passivation layer (e.g., a corner region of the passivation layer) in the S-type passivation layer test structure and the interdigitated passivation layer test structure; in the stepped passivation layer test structure provided in this embodiment, a distinct corrosion hole can be detected at a specific position of the passivation layer (e.g., a corner region of the passivation layer, i.e., a region indicated by a circle in fig. 7), which indicates that a defect exists at the specific position of the passivation layer (i.e., the corner region of the passivation layer). Compared with the S-type passivation layer test structure and the interdigital passivation layer test structure, the passivation layer test structure provided by the embodiment can effectively detect whether defects occur at a special position of the passivation layer in the semiconductor device, especially in a corner region of the passivation layer.

In summary, the present invention provides a passivation layer testing structure for testing the integrity of a passivation layer. The passivation layer test structure includes: the structure layer comprises a plurality of conductive wires, and the conductive wires comprise at least one step-type structure; and passivation layers are formed on the surfaces of the substrate and the structural layer. According to the passivation layer test result provided by the invention, the stepped passivation layer test structure is provided, so that whether defects exist in a special position of the passivation layer, particularly in a corner area of the passivation layer is effectively detected, and the integrity of the passivation layer in a semiconductor device is checked. Compared with the existing passivation layer test structure, the test result of the passivation layer integrity test by adopting the passivation layer test structure provided by the invention has higher reliability.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A passivation layer test structure for testing the integrity of a passivation layer, comprising:

the structure layer comprises a plurality of conductive wires, and the conductive wires comprise at least one step-type structure; and passivation layers are formed on the surfaces of the substrate and the structural layer.

2. The passivation layer test structure of claim 1, wherein the conductive line comprises a number of step-type structures arranged in a consecutive repetition or a number of step-type structures arranged in a mirror image.

3. The passivation layer test structure of claim 1, wherein the step structure comprises a first bottom edge and a second bottom edge connected, and a length L of the first bottom edge₁Is greater than the length L of the second bottom edge₂。

4. The passivation layer test structure of claim 3, wherein a length L of the first bottom edge₁And minimum design rule X₁Has a relationship of L₁≥5X₁。

5. The passivation layer test structure of claim 3, wherein the length L of the second bottom edge₂And minimum design rule X₂Has a relationship of X₂≤L₂≤3X₂。

6. The passivation layer test structure of claim 3, wherein the first base edge and the second base edge are angled at an angle of 70 ° -110 °.

7. The passivation layer test structure of claim 1, wherein the number of the conductive lines is N, and 3 ≦ N ≦ 8, the conductive lines being parallel to each other.

8. The passivation layer test structure of claim 1, wherein the passivation layer test structure is subjected to an integrity test of the passivation layer by an electrical test or a chemical test.

9. The passivation layer test structure of claim 8, wherein the step of electrically testing comprises: and forming a conductive material layer on the surface of the passivation layer, and judging whether the passivation layer is complete or not by detecting the resistance between the structural layer and the conductive material layer.

10. The passivation layer test structure of claim 8, wherein the chemical test uses a chemical solution to etch the passivation layer test structure, and the integrity of the passivation layer is determined by observing the etched topography of the passivation layer test structure.

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