Sheet resistance test unit and structure

Abstract

This invention discloses a sheet resistance testing unit and structure, belonging to the field of semiconductor technology. The sheet resistance testing unit includes a first resistor, formed by the length and width of a layout design; and a second resistor with the same layout design dimensions as the first resistor, and an angle between the first and second resistors to achieve mutual resistance compensation. The second resistor is also connected to the first resistor via a connector to ensure that the current flow directions in the first resistor, the second resistor, and the connector are the same. By providing a first resistor and a second resistor with correspondingly equal layout dimensions and the same current direction, under the same process fluctuation conditions, the differential polarities of the first and second resistors are opposite, and the resulting resistance value deviations can be mutually compensated, effectively reducing the impact of active region process fluctuations on sheet resistance testing in small-size applications.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a sheet resistance testing unit and structure. Background Technology

[0002] Traditional sheet resistance test keys are single rectangular structures. The ratio of the test key's length direction CD (critical dimension) to its width direction CD is called the number of squares. Sheet resistance test keys with different numbers of squares are usually placed inside the wafer to simulate the stability of related processes.

[0003] The current flow direction of a sheet resistance test structure is generally lateral, and the number of squares in a conventional test bond design is greater than one, meaning the CD in the length direction is greater than the CD in the width direction. From a process perspective, the CD of a sheet resistance test structure is generally determined by the photolithography / etching process of the active area in standard CMOS technology. However, in actual wafer manufacturing, the photolithography / etching process of the active area inevitably experiences a certain degree of process fluctuation. Therefore, there is a problem where the inline CD does not reach the design size. This process fluctuation has almost negligible impact on the testing of sheet resistance test bonds at the micrometer level, but its impact on the testing of small-sized sheet resistance test bonds at the nanometer level cannot be ignored.

[0004] It should be noted that the information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a sheet resistance testing unit and structure to solve the problem of process fluctuations affecting small-sized sheet resistance testing keys.

[0006] To solve the above technical problems, the present invention provides a sheet resistance testing unit, comprising:

[0007] The first resistor is formed by the length and width of the layout design;

[0008] The second resistor has the same layout design dimensions as the first resistor, and there is an angle between the first resistor and the second resistor to achieve mutual resistance compensation. The second resistor is also connected to the first resistor through a connector so that the current flow direction in the first resistor, the second resistor and the connector is the same.

[0009] Preferably, the angle between the first resistor and the second resistor is 90 degrees.

[0010] Preferably, the first resistor has a plurality of first contact electrodes arranged therein, and at least some of the first contact electrodes are connected to one end of the connector.

[0011] Preferably, the second resistor has a plurality of second contact electrodes arranged therein, and at least a portion of the second contact electrodes are connected to the other end of the connector.

[0012] Preferably, the first contact electrode, the second contact electrode, and the connector are all made of metal.

[0013] A sheet resistance test structure includes multiple sheet resistance test units connected in series end to end.

[0014] Preferably, multiple sheet resistance test units are connected end to end in a serpentine resistance chain.

[0015] In the sheet resistance testing unit provided by the present invention, by providing a first resistor and a second resistor with the same layout size and the same current direction, under the same process fluctuation conditions, the differential positive and negative values ​​of the first resistor and the second resistor are opposite, and the resulting resistance value deviation can compensate for each other, which can effectively reduce the impact of active area process fluctuations on sheet resistance testing under small size conditions.

[0016] The sheet resistance testing structure provided by this invention and the sheet resistance testing unit provided by this invention belong to the same inventive concept. Therefore, the sheet resistance testing structure provided by this invention has at least all the advantages of the sheet resistance testing unit provided by this invention, which will not be repeated here. Attached Figure Description

[0017] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0018] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of another embodiment of the present invention.

[0020] In the attached image:

[0021] 10. First resistor; 11. First contact electrode; 12. First interconnect; 13. Connector; 20. Second resistor; 21. Second contact electrode; 22. Second interconnect; 30. Third resistor; 40. Fourth resistor; 50. Fifth resistor; 60. Sixth resistor. Detailed Implementation

[0022] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0023] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; the term “at least two” is generally used to mean “two or more”; furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," and "third" may explicitly or implicitly include one or at least two of those features. The term "proximal" typically refers to the end closer to the operator, and the term "distal" typically refers to the end closer to the patient. "One end" and "the other end," as well as "proximal" and "distal," generally refer to two corresponding parts, including not only endpoints. The terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two elements or interactions between two elements. Furthermore, as used in this invention, the placement of one element on another element generally only indicates a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of another element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] The inventors discovered that the actual resistance value of a sheet resistor is affected by the error between the layout size and the manufacturing process size. Furthermore, for sheet resistors with a certain length and width, the smaller width often has a relatively larger impact on the final resistance value.

[0025] Based on this, the core idea of ​​this invention is to provide a first resistor and a second resistor with the same layout size and the same current direction. Therefore, under the same process fluctuation conditions, the differentials of the first resistor and the second resistor are opposite, and the resulting resistance value deviations can compensate for each other. This can effectively reduce the impact of process fluctuations in the active area on the block resistance test under small size conditions.

[0026] For details, please refer to Figure 1 This is a schematic diagram of an embodiment of the present invention. Figure 1 As shown, a sheet resistance testing unit includes:

[0027] The first resistor 10 is formed by the length and width of the layout design;

[0028] The second resistor 20 has the same layout design dimensions as the first resistor 10, and the first resistor 10 and the second resistor 20 have an included angle to achieve mutual resistance compensation. The second resistor 20 is also connected to the first resistor 10 via a connector 13 so that the current flow direction in the first resistor 10, the second resistor 20, and the connector 13 is the same. The length and width of the layout design of the second resistor 20 are the same as the length and width of the layout design of the first resistor 10.

[0029] According to the sheet resistance formula, the sheet resistance R is tested. sq It can be represented as:

[0030]

[0031] Where sq represents the number of blocks, U represents the voltage, i represents the measured current, L represents the actual length dimension, W represents the actual width dimension, L0 represents the length dimension on the layout, and W0 represents the width dimension on the layout. For example... Figure 1 As shown, the current flow directions in the first resistor 10, the second resistor 20, and the connector 13 are the same. The first resistor 10, the second resistor 20, and the connector 13 are configured to have the current flowing in the X direction. The first resistor 10 and the second resistor 20 have the same layout design dimensions, forming a complementary coupled block resistor test structure. The first resistor 10 and the second resistor 20 are connected in series through the connector 13. The second resistor 20 can be regarded as the first resistor 10 rotated by a certain angle, such as 90°, as shown in the above formula. L0 and W0 are the length and width of the first resistor 10 and the second resistor 20 set on the layout, respectively.

[0032] When the first resistor 10 is affected by process fluctuations, the actual width W1 of the first resistor 10 has a significant impact on the resistance value. The error between the actual length L1 of the first resistor 10 and the length L0 on the layout is negligible. Since L1 is approximately L0, the corresponding derivative is:

[0033]

[0034] Furthermore, considering that the deviation between W1 and W0 will not be significant under actual process conditions, and that W1 and W0 are approximately equal, the differential can be further written as:

[0035]

[0036] Similarly, when the second resistor 20 is affected by process fluctuations, the actual width W2 of the second resistor 20 has a significant impact on the resistance value. The error between the actual length L2 of the second resistor 20 and the length L0 on the layout is negligible, L2 is approximately L0, and under actual process conditions, the deviation between W2 and W0 will not be significant. Therefore, the corresponding differential is:

[0037]

[0038] Combining equations (1) and (2), the actual width W1 of the first resistor 10 and the actual width W2 of the second resistor 20 are approximately equal to the width W0 of the layout design. The differential values ​​of the first resistor 10 and the second resistor 20 are almost equal. When the first resistor 10 and the second resistor 20 are affected by process disturbances and deviate from the design size, the positive and negative values ​​of the differential of the square resistors of the two structures are opposite. When the first resistor 10 and the second resistor 20 are connected in series, the influence of process fluctuations in the active area on the square resistor test under small size conditions can be effectively reduced.

[0039] It is understandable that the angle between the first resistor 10 and the second resistor 20 is 90 degrees.

[0040] Specifically, the first resistor 10 has a plurality of first contact electrodes 11 arranged therein, and at least a portion of the first contact electrodes 11 are connected to one end of the connector 13. The second resistor 20 has a plurality of second contact electrodes 21 arranged therein, and at least a portion of the second contact electrodes 21 are connected to the other end of the connector 13.

[0041] The arrangement of the first contact electrode 11 in the first resistor 10 and the second contact electrode 21 in the second resistor 20 ensures that the current I always flows in the X direction.

[0042] For example, such as Figure 1In the arrangement of the first resistor 10, four first contact electrodes 11 are arrayed. Two first contact electrodes 11 are located at one end of the first resistor 10 and connected through a first interconnect 12, which can be used to connect to external devices and draw current. The remaining two first contact electrodes 11 are located at the other end of the first resistor 10 and connected through a connector 13 to the second contact electrodes 21 on the second resistor 20. For example, twelve second contact electrodes 21 are arranged on the second resistor 20 in a 6x2 matrix. One column of second contact electrodes 21 closest to the first resistor 10 is connected to the first resistor 10 through the connector 13, and the other column of second contact electrodes 21 can be interconnected through the second interconnect 22, which can also draw current. Obviously, the arrangement of the first contact electrodes 11 and the second contact electrodes 21 is not limited to this, and other arrangements will not be described here.

[0043] In one embodiment, the first contact electrode 11, the second contact electrode 21, and the connector 13 are all made of metal. For example, the first contact electrode 11, the second contact electrode 21, and the connector 13 are all made of metal. The first resistor 10 and the second resistor 20 are, for example, polysilicon resistors or NiSi resistors, without any specific limitation.

[0044] Based on the same technical concept, this disclosure also provides a sheet resistance test structure, including multiple sheet resistance test units connected in series end to end. Taking the aforementioned sheet resistance unit as the smallest unit in the test structure, multiple sheet resistance test units are connected in series to form the desired test structure, for example, multiple... Figure 1 The sheet resistance test units shown are connected end-to-end. It is not specifically limited to whether the first resistor 10 or the second resistor 20 is the beginning and end of the entire sheet resistance test unit. On the first resistor 10 and the second resistor 20, the electrodes without connectors 13 can be used to connect to another sheet resistance test unit, so that the current in the entire sheet resistance test structure is along the X direction; or multiple sheet resistance test units can be connected end-to-end in a serpentine resistor chain, with connectors 13 of corresponding shapes at the connection points of two sheet resistance test units to change the current flow direction, so that the current flows in opposite directions in the two connected sheet resistance test units, such as... Figure 2 As shown, the first resistor 10, the second resistor 20, the third resistor 30, the fourth resistor 40, the fifth resistor 50 and the sixth resistor 60 are connected end to end to form a serpentine resistor chain.

[0045] The above description is only a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A sheet resistance testing unit, characterized in that, include: The first resistor is formed by the length and width of the layout design; The second resistor has the same layout design dimensions as the first resistor, and there is an angle between the first resistor and the second resistor to achieve mutual resistance compensation. The second resistor is also connected to the first resistor through a connector so that the current flow direction in the first resistor, the second resistor and the connector is the same.

2. The sheet resistance testing unit according to claim 1, characterized in that, The angle between the first resistor and the second resistor is 90 degrees.

3. The sheet resistance testing unit according to claim 1, characterized in that, The first resistor has a plurality of first contact electrodes arranged therein, and at least some of the first contact electrodes are connected to one end of the connector.

4. The sheet resistance testing unit according to claim 3, characterized in that, The second resistor has a plurality of second contact electrodes arranged therein, and at least some of the second contact electrodes are connected to the other end of the connector.

5. The sheet resistance testing unit according to claim 4, characterized in that, The first contact electrode, the second contact electrode, and the connector are all made of metal.

6. A sheet resistance testing structure, characterized in that, It includes multiple sheet resistance test units as described in any one of claims 1-5, connected end to end in series.

7. The sheet resistance testing structure according to claim 6, characterized in that, Multiple of the aforementioned sheet resistance test units are connected end to end in a serpentine resistance chain.

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