Via leakage and breakdown testing

Through hole leakage and breakdown test

VIA LEAKAGE AND BREAKDOWN TESTING

The present invention relates to integrated circuits. More specifically, the present invention relates to through hole leakage and breakdown testing.

An integrated circuit (IC) is a semiconductor device that contains many small, interconnected components. These components work together to enable the IC to perform tasks such as controlling electronic devices or performing logical operations. IC can be seen in computers, mobile phones, and many other electronic devices.

ICs and other semiconductor devices generally include multiple layers. The connections between layers are called through holes. In integrated circuit design, through holes are small openings in the insulating oxide layer that provide conductive connections between different layers of the IC. A plurality of through holes are coupled together to connect one conductive area in an IC to another conductive area in the same or an adjacent IC.

The through hole will have errors during manufacturing. When a manufacturing error occurs in the through hole, the through hole may not conduct properly, which may prevent the IC from functioning properly. Therefore, testing of through-hole structures is an important aspect of IC production and reliability.

The leakage and breakdown related to the through hole is one of the most important issues in the development and reliability of the back-end (BEOL) program. Traditional through-hole testing structures such as through-hole-comb (Figure 1) and tangled through-hole chain (Figure 2) cannot be accurately diagnosed. The root cause of the problems related to broken through holes (in Figures 1 and 2, M1 and M2 are metal layers, and V1 is through holes). For example, this type of structure cannot separately analyze and distinguish the difference between the through hole leakage/breakdown problem that occurs at the top of the through hole and the through hole leakage/breakdown problem that occurs at the bottom of the through hole. This information is essential for program development, especially for self-aligned contact programs. In addition, this type of through-hole test structure cannot electrically identify through-hole overlay problems, and cannot distinguish between through-hole-line and line-line leakage and/or breakdown.

A first aspect includes a test structure including: a first three-terminal through-hole test structure, which includes: a first terminal coupled to a first set of sensors in the top layer of the structure A second end, the second end is coupled to a second set of sensing lines in the top layer of the structure, wherein the first set of sensing lines and the second set of sensing lines are arranged in a comb tooth configuration; Three terminals, the third terminal is coupled to a third set of sensing lines in the bottom layer of the structure; and a plurality of through holes are electrically coupled to the second set of sensing lines in the top layer of the structure The third set of sensing lines in the bottom layer of the structure are measured from the measurement line, and each through hole has a through hole top end and a through hole bottom end.

A second aspect includes a semiconductor wafer, the semiconductor wafer including: a first three-terminal through-hole test structure, which includes: a first terminal coupled to the first group in the top layer of the structure A sensing line; a second end, the second end is coupled to a second set of sensing lines in the top layer of the structure, wherein the first set of sensing lines and the second set of sensing lines are arranged in a comb tooth configuration; The third terminal, the third terminal is coupled to the first in the bottom layer of the structure Three sets of sensing lines; and a plurality of through holes, the plurality of through holes are electrically coupled to the second set of sensing lines in the top layer of the structure to the third set of sensing lines in the bottom layer of the structure, each through hole It has a top end of a through hole and a bottom end of the through hole.

A third aspect includes a test method including: providing a three-point through hole test structure including at least one through hole; and using the three-point through hole test structure to isolate and obtain a top end of the through hole The measurement data of the top end of the through hole and the bottom end data of the through hole located at the bottom end of the through hole.

<p>10Through hole test structure</p><p>12Upper floor</p><p>14Lower</p><p>20Comparison Chart</p><p>30Test structure</p><p>32Upper Floor</p><p>34Lower</p><p>50Through hole test structure</p><p>50-1Through hole test structure</p><p>50-2Through hole test structure</p><p>50-NThrough hole test structure</p><p>60Breakdown voltage measurement</p><p>62Line</p><p>100Semiconductor Wafer</p><p>102Integrated Circuit Chip</p><p>104Saw area</p><p>T1First endpoint</p><p>T2Second terminal</p><p>T3Third end point</p>

These and other features of the present invention will be more easily understood through the following detailed descriptions of various aspects of the present invention, together with the drawings showing specific embodiments of the present invention.

Figure 1 shows the related technology through-hole-comb test structure.

Figure 2 shows the related technology tangled through-hole chain test structure.

Figure 3 illustrates a three-point through hole test structure according to a specific embodiment.

Figures 4A and 4B show a pair of through hole test structures in Figure 3 according to specific embodiments.

Figure 5 is an illustrative measurement comparison diagram obtained using the through hole test structure shown in Figures 4A and 4B at the through-hole-top and through-hole-bottom ends, respectively.

FIG. 6 illustrates a three-terminal test structure used in conjunction with the through-hole test structure of FIG. 3 according to a specific embodiment.

FIGS. 7A and 7B illustrate the through hole test structure of FIG. 3 used together with the test structure of FIG. 6 according to specific embodiments.

Figure 8 is an explanatory comparison diagram of through-hole and non-through-hole sensing data collected using the test structure shown in Figures 7A and 7B.

Figure 9 illustrates another three-point through hole test structure according to a specific embodiment.

FIG. 10 shows a plurality of three-point through hole test structures in FIG. 9 according to a specific embodiment.

Figures 11A and 11B respectively illustrate the effects of positive X through hole displacement and negative X through hole displacement according to specific embodiments.

Fig. 12 is an explanatory diagram of the relationship between breakdown voltage measurement and misalignment according to a specific embodiment.

FIG. 13 is an illustrative semiconductor wafer including a through-hole test structure according to a specific embodiment.

As mentioned above, the object of the invention disclosed herein relates to integrated circuits. More specifically, the purpose of the present invention is related to through-hole leakage and breakdown testing.

In a specific embodiment, the through-hole test structure of the present disclosure (hereinafter referred to as "through-hole test structure") may be located in the kerf area surrounding the semiconductor die on the semiconductor wafer. The kerf area is the cutting area where the semiconductor wafer is divided into individual semiconductor dies when the manufacturing process is completed. In other specific embodiments, the through hole test structure may also be located inside the semiconductor die. Through-hole test structures can be formed on semiconductor wafers using semiconductor processing technology become.

FIG. 3 illustrates a three-point through hole test structure 10 according to a specific embodiment. The through hole test structure 10 includes a plurality of conductive (for example, metal) sensing lines arranged in a plurality of layers (for example, two layers), and a plurality of conductive through holes V0 that connect the sensing lines in different layers together.

In the specific embodiment shown in FIG. 3, the through-hole test structure 10 includes an upper layer 12 that includes a plurality of spaced and alternating sensing lines E1 and E2. Each sensing line E1 is designated as a "Leak Above" sensing line. The sensing line E1 in the upper layer 12 of the through hole test structure 10 is electrically coupled to the first terminal T1.

The through hole test structure 10 further includes a lower layer 14 including a plurality of spaced-apart sensing lines E3. The sensing line E3 is designated as a "Leak Below" sensing line. The sensing line E2 in the upper layer 12 of the through hole testing structure 10 is electrically coupled to the sensing line E3 in the lower layer 14 of the through hole testing structure 10 through the through hole V0. The sensing line E2 is electrically coupled to the second terminal T2. The sensing line E3 is electrically coupled to the third terminal T3. In a specific embodiment, the sensing lines E1 and E2 in the upper layer 12 of the through hole testing structure 10 and the sensing line E3 in the lower layer 14 of the through hole testing structure 10 are perpendicular to each other. As shown in Figure 3, the sensing line E1 connected to the first terminal T1 and the sensing line E2 connected to the second terminal T2 are arranged in a comb tooth configuration (for example, the sensing line E1 alternates with the sensing line E2).

Unlike existing through hole test structures such as the through hole-comb test structure shown in Figure 1 and the tangled through hole chain test structure shown in Figure 2, the through hole test structure 10 of the present disclosure can The top of the hole (through The problem that occurs at the hole-top) is distinguished from the problem that occurs at the bottom of the through hole (through hole-bottom). Furthermore, the through hole test structure 10 can be used to distinguish between through hole-line and line-line problems. The through-hole testing structure 10 can also be used to identify through-hole overlap problems.

According to specific embodiments, as shown in FIGS. 4A and 4B, multiple cloned copies of the through hole test structure 10 can be provided. As shown in Figure 4A, the terminal T3 can be kept floating, and a bias voltage V is applied between the sensing lines E1 and E2 passing through the terminals T1 and T2, respectively._via-topCome to isolate and investigate the through hole-top problem. Furthermore, as shown in Figure 4B, the terminal T1 can be kept floating, and a bias voltage V is applied between the sensing lines E2 and E3 passing through the terminals T2 and T3, respectively._via-botCome to isolate and investigate the through-hole-bottom problem. The bias voltage V applied to the through-hole test structure 10 in Figures 4A and 4B_via-top, V_via-botIt can be different, and all kinds of data (for example: leakage current, breakdown voltage, etc.) can be collected and evaluated.

FIG. 5 shows an illustrative comparison of through-hole-top and through-hole-bottom sensing data obtained by using the through-hole test structure 10 shown in FIGS. 4A and 4B, for example, FIG. 2 0. In this embodiment, it is clearly seen that the through-hole-bottom end has a higher breakdown voltage problem than the through-hole-top end. In other words, the breakdown voltage measured at the bottom of the through hole is smaller than the breakdown voltage measured at the top of the through hole. The breakdown voltage can be measured, for example, by applying a voltage that rises linearly at a fixed rate. Leakage current is measured when the voltage rises. The point where the leakage current rises sharply (for example: suddenly) is the breakdown voltage.

Other data can be derived by using a test structure similar to that shown in Figure 3 but without the through hole V0. For example, as shown in Figure 6 As shown, the test structure 30 is essentially a clone (but does not have any through holes V0) of the through-hole test structure 10 in FIG. , E2. The sensing line E1 in the upper layer 32 of the test structure 30 is electrically coupled to the first terminal T1. The sensing line E2 in the upper layer 32 of the test structure 30 is electrically coupled to the second terminal T2.

The test structure 30 further includes a lower layer 34 which includes a plurality of spaced-apart sensing lines E3. However, unlike the through hole test structure 10 shown in FIG. 3, the sensing line E2 in the upper layer 32 of the test structure 30 is not electrically coupled to the sensing line E3 in the lower layer 34 of the test structure 30. In the test structure 30, the sensing line E3 is electrically coupled to the third terminal T3.

According to specific embodiments, the through-hole-line versus line-line problem can be verified by comparing the operation of the through-hole test structure 10 in FIG. 3 with the operation of the test structure 30 in FIG. 6 under certain operating conditions. For example, as shown in FIGS. 7A and 7B, the end points T1 and T3 of each test structure 10 and 30 are connected together. Bias voltage V_biasIt is applied between the end points (T1, T3) and T2 of the test structures 10 and 30. The bias voltage V applied to the test structures 10 and 30 shown in Figs. 7A and 7B_biasIt can be different, and various data (for example: breakdown voltage data) can be collected and evaluated.

Fig. 8 shows an illustrative comparison diagram of through-hole and non-through-hole sensing data collected using the test structures 10 and 30 shown in Figs. 7A and 7B, respectively. In this embodiment, it is clearly seen that the through hole V0 has a great influence on the breakdown voltage, and the size of the bottom end of the through hole V0 is poorly controlled.

FIG. 9 illustrates another three-point through hole test structure 50 according to a specific embodiment. The through hole test structure 50 is similar to the through hole shown in Figure 3 The difference of the hole test structure 10 is that the distance between the through hole V0 and the adjacent line (for example, the sensing line E1) has been modulated by shifting the through hole V0 by a distance along the X axis and/or the Y axis. As shown in Figure 10, a plurality of these through-hole test structures 50-1, 50-2,..., 50-N can be provided for testing purposes. For each through-hole test structure, the through-hole V0 is along the X axis And/or the Y-axis shift amount is different.

Using the through-hole test structure 50, various data can be quantitatively captured and used for analysis, such as overlay, through-hole size, line width, through-hole-line, and other issues. For example, Figures 11A and 11B respectively show the breakdown voltage effect caused by the negative X shift and the positive X shift, and the arrow indicates that the misalignment of the through hole V0 is increased. It can be easily seen from Figures 11A and 11B that the breakdown voltage decreases as the misalignment increases along the X direction.

Other information can be obtained by comparing the breakdown voltage with the through-hole V0 misalignment for a plurality of through-hole test structures 50 with different through-hole V0 misalignment. Figure 12 shows an explanatory diagram showing the relationship between breakdown voltage and misalignment.

In Figure 12, a plurality of breakdown voltage measurements 60 are performed using a plurality of test structures 50 with different through holes V0 misalignment along the X direction. As can be seen, the highest breakdown voltage V_bd-maxIt appears when there is a -2nm through hole misalignment. This indicates that after semiconductor wafer processing, a total stack shift of -2nm X_OL. Therefore, the -2nm through-hole misalignment structure can be used to bring back the +2nm stacking shift to provide the most centered structure with the highest breakdown voltage.

Actual distance between two lines X_PPCan be based on leading to zero The total of the negative and positive misalignment distances of the breakdown voltage (that is, the point where the through hole V0 will touch the adjacent circuit) is extracted from the relationship diagram in Figure 12. Through hole-line spacing can be obtained by subtracting the overlap shift X from the original design spacing_OLTo determine. Furthermore, as shown in Figure 12, the breakdown field strength E_BDIt is given by the slope of line 62.

FIG. 13 shows a schematic top view of a semiconductor wafer 100 which includes integrated circuit chips 102 and a saw area 104 between the integrated circuit chips 102. The through hole test structure described above according to the specific embodiment may be formed in the kerf area 104.

Various exemplary specific embodiments of the through-hole test structure have been disclosed herein. However, those skilled in the art should understand that the number of components (for example, sensing lines, through holes, endpoints, etc.) in this type of through-hole test structure is not limited to those shown in the figure.

The terminology used herein is only for the purpose of describing specific illustrative embodiments, and is not intended to be limiting. When the singular forms "a" and "the" are used herein, the intention may be to also include the plural form, unless the content clearly indicates otherwise. The words "comprising", "including" and "having" are compatible, and therefore indicate the existence of the described features, wholes, steps, operations, elements and/or elements, but do not exclude one or more other features, wholes The existence or addition of, steps, operations, elements, elements, and/or groups thereof. The method steps, procedures and operations described herein are not to be regarded as necessary to be carried out in the specific order described or shown, unless the order of execution is specifically determined. It should also be understood that additional or alternative steps can be used.

When one element or layer is said to be located in another element or layer When "on", "coupled to", "connected to" or "coupled to" another element, the element or layer can be directly on, joined, connected or coupled to the other element or layer Elements or layers, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on", "directly bonded to", "directly connected to" or "directly coupled to" another element or layer, it may be There are no intervening elements or layers. The words used to describe the relationship between elements and elements should be interpreted in a similar way (for example: "between" as opposed to "directly between", and "adjacent" as opposed to "Directly adjacent" etc.). When the term "and/or" is used in this article, it includes any and all combinations of one or more of the related listed items.

Spatial relative terms such as "inner", "outer", "below", "below", "below", "above", "upper" and the like can be used in this article for convenience, as shown in the figure Shown is the relationship of one element or feature to another element or feature(s). In addition to the orientation shown in the figure, the relative terminology of space can also include different orientations of devices used or operated. For example, if the device in the figure is overturned, the elements described as being positioned "below" or "below" other elements or features will be oriented as being "above" these other elements or features. Therefore, the exemplary term "below" can encompass both the above and below orientations. The device can be oriented in another way (rotated 90 degrees or rotated to other orientations), so that the spatial relative descriptors used in this article can be interpreted.

The foregoing description of various aspects of the present invention has been introduced for descriptive and illustrative purposes. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are clearly possible. this Such modifications and variations that may be obvious to those skilled in the art are as defined in the scope of the attached patent application, and are included in the scope of the present invention.

The description of the specific embodiments of the present invention has been introduced for the purpose of description, but the intention is not to be exhaustive or limited to the specific embodiments disclosed. Many modifications and variations will be obvious to those skilled in the art, but they will not depart from the scope and spirit of the specific embodiments. The terms used in this document are selected to best explain the principles of specific embodiments, practical applications or technical improvements to commercially available technologies, or to enable those skilled in the art to understand the specific embodiments disclosed herein.