Test structure and test method

Abstract

A test structure and a test method. The test structure comprises a first resistor (21) and at least a second resistor (22) electrically connected in series with the first resistor (21), the number of the second resistors (22) being MxN, M and N being positive integers, and all the second resistors (22) being electrically connected in parallel with each other. The resistance difference is obtained by setting different numbers of resistors, so as to accurately calculate the resistance value of the phase change material and the heater.

Description

Technical Field

[0001] This invention relates to the field of semiconductor testing, and more particularly to a testing structure and testing method. Background Technology

[0002] Phase-change memory (PCM) uses a phase-change material layer and a corresponding heater connected in series to form a variable resistor as the storage medium. Therefore, accurately measuring the resistance value of the resistor formed by the heater and the phase-change material layer is an important technical problem. (Appendix) Figure 1 The diagram shows two existing arrangements of the heater and phase change material layer. The measured resistance value R... th The resistance value R of heater 11a (11b) is equal to ch The resistance value R of the phase change material layer 12a (12b) GST The sum, i.e., R th =R ch +R GST For cases where the heater size is small, i.e., attached Figure 1 In the case shown in (a), we assume the heater resistance value R ch Much greater than the resistivity R of the phase change material layer GST Therefore, the measured resistance value R can be obtained. th Directly equivalent to the heater resistance value R ch For heaters that are large in size, i.e., with additional... Figure 1 In the case shown in (b), since the heater is made of a metallic material, its resistivity is much lower than that of a phase change material. Therefore, for the same dimensions, we consider the heater resistance value R to be higher. ch Much smaller than the resistivity R of the phase change material layer GST Therefore, the measured resistance value R can be obtained. th The direct equivalent to the resistance value R of the phase change material layer GST Clearly, the above algorithms all make equivalent approximations, and therefore cannot accurately measure the resistance values ​​of the two. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a test structure and test method that can accurately measure the resistance value of the resistor formed by the heater and the phase change material layer.

[0004] To address the aforementioned problems, the present invention provides a test structure comprising: a first resistor; and at least one second resistor connected in electrical series with the first resistor, wherein the number of second resistors is M×N, where M and N are positive integers, and all the second resistors are connected in electrical parallel with each other.

[0005] To address the aforementioned problems, this invention provides a testing method comprising the following steps: setting up a first test structure, the first test structure including a first resistor and at least one second resistor electrically connected in series with the first resistor, the number of second resistors being 1×1, and all the second resistors being electrically connected in parallel with each other; setting up a second test structure, the second test structure including a first resistor and at least one second resistor electrically connected in series with the first resistor, the number of second resistors being 2×2; measuring the resistance values ​​of the first test structure and the second test structure, and calculating their difference; calculating the resistance value of the second resistor based on the calculated difference in resistance values; and calculating the resistance value of the first resistor based on the obtained resistance value of the second resistor, combined with the resistance value of the first test structure or the second test structure.

[0006] This invention obtains the resistance difference by setting different numbers of resistors, thereby accurately calculating the resistance values ​​of the phase change material and the heater. Attached Figure Description

[0007] Appendix Figure 1 The diagram shows two arrangements of heaters and phase change material layers in the prior art.

[0008] Appendix Figure 2 The diagram shown is a schematic diagram of the test structure according to a specific embodiment of the present invention.

[0009] Appendix Figure 3 The diagram shown is a schematic diagram of the test structure according to a specific embodiment of the present invention.

[0010] Appendix Figure 4 The diagram shown is a schematic diagram of the test structure according to a specific embodiment of the present invention.

[0011] Appendix Figure 5 The diagram shows the implementation steps of the testing method according to a specific embodiment of the present invention.

[0012] Appendix Figure 6 The image shows the use of an attachment. Figure 5 The diagram illustrates the specific implementation method of applying current to perform resistance testing on the first and second test structures. Detailed Implementation

[0013] The following detailed description, in conjunction with the accompanying drawings, illustrates the specific implementation of the test structure and test method provided by this invention.

[0014] The following describes a specific implementation of the test structure described in this invention, in conjunction with the accompanying drawings.

[0015] Appendix Figure 2The diagram shown is a schematic representation of another specific embodiment of the test structure described in this invention, including: a first resistor 21, and at least one second resistor 22 connected in electrical series with the first resistor. The number of second resistors is M×N, where M and N are positive integers. This specific embodiment uses a configuration of M=N=1, i.e., one resistor.

[0016] Appendix Figure 3 The diagram shown is a schematic representation of another specific embodiment of the test structure described in this invention, including: a first resistor 21, and at least one second resistor 22 electrically connected in series with the first resistor. The number of second resistors is M×N, where M and N are positive integers. In this specific embodiment, 2×1 resistors are set with M=2 and N=1, i.e., 2 resistors.

[0017] Based on the content embodied in the above specific embodiments, in other specific embodiments, different arrangements of the second resistor 22 can be obtained by setting different numbers of M and N.

[0018] The above structure is used to test the resistance value R of the first resistor 21. GST and the resistance value R of the second resistor 22 ch Since the number of second resistors 22 used in the above test structures is different, any two test structures in the above specific embodiments can be used to measure the total series resistance Rth1 and R of the above structures respectively. th2 Rth1 is an appendix. Figure 2 The total series resistance of the test structure is Rth1 = R ch +R GST +R PAS ,R PAS R is the sum of electrode resistance and background parasitic resistance. th3 For the appendix Figure 3 The total series resistance of the test structure is Rth2 = R ch / 2+R GST +R PAS So R th1 -R th2 The value is considered to be the change in resistance caused by the change in the number of second resistors 22, and the resistance value R of the second resistor 22 can be calculated. ch According to Rth1-Rth2=R ch / 2, can remove electrode resistance and background parasitic resistance R PAS Accurately calculate the resistance value R of the second resistor 22. ch .

[0019] Appendix Figure 4The diagram shown is a schematic of the structure described in this specific embodiment, including: a first resistor 21, and at least one second resistor 22 electrically connected in series with the first resistor. In this specific embodiment, the test structure is used to test the variable resistor structure of a phase-change memory. The first resistor is a phase-change material layer, such as GST material, and the second resistor is a heater. The number of second resistors is M×N, where M and N are positive integers. All the second resistors are electrically connected in parallel with each other, and preferably arranged in an array with equal spacing in M ​​rows and N columns. This specific embodiment uses a setting of M=N=2 to set 2×2 resistors, i.e., 4 resistors, as an example for description. The total series resistance of the test structure in this specific embodiment is Rth3=R ch / 4+R GST +R PAS The advantage of M equaling N is that it ensures all the second resistors 22 are in the same electrical environment, reducing systematic errors between resistors caused by manufacturing processes and electric field distribution.

[0020] In this specific embodiment, the second resistor 22 is disposed in an insulating dielectric layer 23, the distance between the second resistor 22 and the boundary of the insulating dielectric layer 13 is d, and the distance between the second resistors 22 is 2d. This ensures that the electrical environment of each resistor is consistent, reducing systematic errors between resistors caused by process and electric field distribution.

[0021] Attachment Figure 3 The total series resistance Rth2 of the test structure measured in the embodiment is related to the attached Figure 4 Subtracting the total series resistance Rth3 of the test structure measured in the example, we can obtain Rth2 - Rth3 = R ch / 4. This allows for interactive verification of R through different test structures. ch The correctness of the result is related to the influence of current density on its value.

[0022] The following describes a specific implementation of the test method described in this invention, in conjunction with the accompanying drawings. Figure 5The diagram shows the implementation steps of the method described in this specific embodiment, including: Step S51, setting up a first test structure, the first test structure including a first resistor and at least one second resistor electrically connected in series with the first resistor, the number of second resistors being M1×N1, where M1 and N1 are positive integers, and all the second resistors being electrically connected in parallel with each other; Step S52, setting up a second test structure, the second test structure including a first resistor and at least one second resistor electrically connected in series with the first resistor, the number of second resistors being M2×N Two resistors are used, where M2 and N2 are positive integers, and all the second resistors are electrically connected in parallel. The value of M1×N1 is not equal to the value of M2×N2. Step S53: Measure the resistance values ​​of the first test structure and the second test structure, and calculate their difference. Step S54: Calculate the resistance value of the second resistor based on the difference in the calculated resistance values ​​and the difference between the values ​​of M1×N1 and M2×N2. Step S55: Calculate the resistance value of the first resistor based on the obtained resistance value of the second resistor and the resistance value of the first or second test structure.

[0023] As a specific implementation method, in the above steps, to make the measurement more accurate, as shown in the attached... Figure 6 As shown, during the resistance test of the first and second test structures, the current flow direction is set to flow from the first resistor to the second resistor and from the second resistor to the first resistor, respectively. The resistance values ​​under these two conditions are measured, and the average value is taken as the resistance of the first test structure. This can compensate for systematic errors caused by the process and electric field distribution in the resistor's environment.

[0024] Referring to steps S51 and S52, a first test structure is set up. The first test structure includes a first resistor and at least one second resistor electrically connected in series with the first resistor. The number of second resistors is M1×N1, where M1 and N1 are positive integers. All the second resistors are electrically connected in parallel and arranged in an array with equal spacing in an M1-row and N1-column configuration. A second test structure is set up. The second test structure includes a first resistor and at least one second resistor electrically connected in series with the first resistor. The number of second resistors is M2×N2, where M2 and N2 are positive integers. All the second resistors are electrically connected in parallel and arranged in an array with equal spacing in an M1-row and N1-column configuration. The value of M1×N1 is not equal to the value of M2×N2. This step can adopt any two of the specific embodiments of the above structures. This specific embodiment adopts the appendix. Figures 2-4 The specific implementation shown will be described, i.e., M1 = N1 = 1, M2 = 2, N2 = 1, or M3 = N3 = 2.

[0025] Referring to steps S53 and S54, the resistance value R of the first test structure is measured.th1 The resistance value R of the second test structure th2 The difference between the calculated resistance values ​​is then calculated. Based on this difference, and combined with the difference between M1×N1 and M2×N2, the resistance value of the second resistor is calculated. Since the first test structure has only one second resistor, the parallel resistance value is R. ch The second test structure has two resistors, therefore the resistance value is R. ch / 2. R th1 -R th2 =R ch / 2, based on this, the resistance value R of the second test resistor can be calculated. ch .

[0026] Referring to step S55, based on the obtained resistance value of the second resistor and combined with the resistance value of the first or second test structure, the resistance value of the first resistor is calculated. According to Rth1 = R... ch +R GST , or Rth2 = R ch / 2+R GST The resistance value R of the first resistor can be calculated from these values. GST .

[0027] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A test structure, characterized by, The test structure comprises: a first resistance; and a plurality of second resistances electrically connected in series with the first resistance, the number of the second resistances being M1xN1, M1 and N1 being positive integers, and all the second resistances being electrically connected in parallel with each other. The test structure comprises: a first resistance; and a plurality of second resistances electrically connected in series with the first resistance, the number of the second resistances being M2xN2, M2 and N2 being positive integers, and all the second resistances being electrically connected in parallel with each other, and at least one of M2 and N2 being different from M1 and N1. The test structure is used for testing a variable resistance structure of a phase change memory, the first resistance is a phase change material layer, and the second resistance is a heater.

2. The test structure of claim 1, wherein, The second resistances are arranged in an equidistant array in the form of M rows and N columns.

3. The test structure of claim 1, wherein, The second resistances are arranged in an insulating medium layer, and the distance between the second resistances and the boundary of the insulating medium layer is half the distance between the second resistances.

4. The test structure of claim 3, wherein, M1 is equal to N1.

5. The test structure of claim 1, wherein, The test method comprises the following steps:

6. A test method characterized by, a first test structure is provided, the first test structure comprising a first resistance and a plurality of second resistances electrically connected in series with the first resistance, the number of the second resistances being M1xN1, M1 and N1 being positive integers, and all the second resistances being electrically connected in parallel with each other; a second test structure is provided, the second test structure comprising a first resistance and a plurality of second resistances electrically connected in series with the first resistance, the number of the second resistances being M2xN2, M2 and N2 being positive integers, and all the second resistances being electrically connected in parallel with each other, and the value of M1xN1 being different from the value of M2xN2; the resistance values of the first test structure and the second test structure are measured, and the difference between the resistance values is calculated; the resistance value of the second resistance is calculated according to the difference between the calculated resistance values and the difference between the value of M1xN1 and the value of M2xN2; the resistance value of the first resistance is calculated according to the obtained resistance value of the second resistance and the resistance value of the first test structure or the second test structure. The test method is used for testing a variable resistance structure of a phase change memory, the first resistance is a phase change material layer, and the second resistance is a heater.

7. The test method of claim 6, wherein, The second resistances of the first test structure are arranged in an equidistant array in the form of M1 rows and N1 columns, and the second resistances of the second test structure are arranged in an equidistant array in the form of M2 rows and N2 columns.

8. The test method of claim 6, wherein, The second resistances are arranged in an insulating medium layer, and the distance between the second resistances and the boundary of the insulating medium layer is half the distance between the second resistances.

9. The test method of claim 8, wherein, In the step of measuring the resistance value of the first test structure, the flow direction of the current is set to be from the first resistance to the second resistance and from the second resistance to the first resistance, respectively, the resistance values in the above two cases are tested respectively, and the average value is taken as the resistance of the first test structure.

10. The test method of claim 6, wherein, ​ 11. The test method of claim 6, wherein, In the step of measuring the resistance value of the second test structure, the flow direction of the current is set to flow from the first resistance to the second resistance and from the second resistance to the first resistance respectively, the resistance values in the above two cases are tested respectively, and the average value is taken as the resistance of the second test structure.

12. The test method of claim 6, wherein, The M1=N1=1, and one of the M2 or N2 is equal to 1, and the other is equal to 2.

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