A capacitance measurement structure and method

Abstract

The application provides a kind of capacitance measurement structure and method at least includes: the spaced distribution of being arranged in wafer surface capacitance measurement module, each capacitance measurement module measures corresponding to be measured capacitance, each capacitance measurement module includes sequentially adjacent first branch, second branch and third branch along transverse direction or along longitudinal direction;When the number of measurement resistance is one, measurement resistance is connected between the lower plate of to-be-measured capacitance and second branch;When the number of measurement resistance is two, second branch includes first sub-branch and second sub-branch;Capacitance unit is arranged between first branch and first sub-branch, between first sub-branch and second sub-branch and between second sub-branch and third branch;By setting measurement resistance or measurement resistance and capacitance unit between the plate of to-be-measured capacitance and branch, to-be-measured capacitance and branch form RC loop, and the capacitance value of to-be-measured capacitance less than picofarad level is measured based on measurement resistance. Simple structure, convenient operation, wide application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor integrated circuit manufacturing and measurement, and in particular, to a capacitance measurement structure and method. BACKGROUND

[0002] In the wafer manufacturing process, electrical tests are usually needed to characterize the properties of the chips inside the wafer, so as to evaluate the performance of the wafer and determine whether the wafer meets the process specification. Characterizing the small capacitances in the wafer is an important means of electrical testing, but the small capacitances in the wafer are generally less than picofarad, which makes it difficult to measure and further makes it difficult to accurately measure the small capacitances. Thus, the wafer acceptance test (WAT) brings serious uncertainty.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical solutions of the present application and for the convenience of the understanding of the person skilled in the art. The above technical solutions cannot be considered as known to the person skilled in the art just because they are described in the background of the present application. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the present application aims to provide a capacitance measurement structure and method, which can solve the problems of difficulty in measuring the capacitances less than picofarad inside the wafer and inaccuracy of the measurement results in the prior art.

[0005] To achieve the above-mentioned objects and other related objects, the present application provides a capacitance measurement structure for measuring a to-be-measured capacitance inside a wafer, which comprises at least:

[0006] N capacitance measurement modules arranged at intervals on the surface of the wafer, each of the capacitance measurement modules measuring a corresponding to-be-measured capacitance, each of the capacitance measurement modules comprising a first branch, a second branch and a third branch which are sequentially adjacent in the lateral direction or in the longitudinal direction, wherein the first branch and the second branch are connected to the upper plate and the lower plate of the corresponding to-be-measured capacitance respectively, and N is a natural number greater than 1;

[0007] Each of the capacitance measurement modules corresponds to at least one measurement resistor, and when the number of measurement resistors is one, the measurement resistor is connected between the lower plate of the to-be-measured capacitance and the second branch;

[0008] When the number of the measurement resistors is two, the second branch includes a first sub-branch and a second sub-branch, a first measurement resistor is connected between the upper plate of the to-be-measured capacitor and the first sub-branch, and a second measurement resistor is connected between the lower plate of the to-be-measured capacitor and the second sub-branch; a first capacitor unit is arranged between the first branch and the first sub-branch; a second capacitor unit is arranged between the first sub-branch and the second sub-branch; and a third capacitor unit is arranged between the second sub-branch and the third branch.

[0009] The to-be-measured capacitor is measured by a test device connected to the capacitor measurement structure.

[0010] Optionally, the measurement resistor is located on the surface of the wafer or inside the wafer.

[0011] Optionally, when the measurement resistor is located on the surface of the wafer, the measurement resistor is a thin-film resistor or a chip resistor; and when the measurement resistor is located inside the wafer, the measurement resistor is formed inside the wafer by etching.

[0012] Optionally, when the number of the measurement resistors is one, the distance between the first branch and the second branch is smaller than the distance between the second branch and the third branch.

[0013] Optionally, when the number of the measurement resistors is two, the distance between the first branch and the first sub-branch is equal to the distance between the first sub-branch and the second sub-branch; and the distance between the first sub-branch and the second sub-branch is equal to the distance between the second sub-branch and the third branch.

[0014] Optionally, when the number of the measurement resistors is one, the first branch, the second branch and the third branch each include a pad, and the shapes and sizes of the pads are equal; and when the number of the measurement resistors is two, the first branch, the third branch, the first sub-branch and the second sub-branch each include a pad, and the shapes and sizes of the pads are equal.

[0015] Optionally, when the pads are arranged in a transverse direction, the top ends of the pads are flush; and when the pads are arranged in a longitudinal direction, the left ends of the pads are flush.

[0016] To achieve the above object and other related objects, the present application provides a capacitor measurement method for measuring a to-be-measured capacitor inside a wafer, and the capacitor measurement method at least includes:

[0017] Step 11: connect the test equipment with each of the capacitive measurement modules in the capacitive measurement structure one by one, measure the to-be-measured capacitance corresponding to each capacitive measurement module, when the measurement resistance corresponding to each capacitive measurement module is one, connect the first branch to zero potential and the second branch to high potential;

[0018] Step 12: keep the first branch at zero potential, switch the second branch from high potential to low potential, and obtain the potential change curve between the first branch and the second branch with time by leading out the signal of the third branch;

[0019] Step 13: obtain the value of the time constant RC based on the potential change curve between the first branch and the second branch, and further obtain the capacitance value of the to-be-measured capacitance C 待测 through the measurement resistance, wherein the first branch, the to-be-measured capacitance C 待测 , the measurement resistance and the second branch form an RC circuit.

[0020] To achieve the above object and other related objects, the application provides a capacitive measurement method for measuring a to-be-measured capacitance inside a wafer, which at least comprises:

[0021] Step 21: connect the test equipment with each of the capacitive measurement modules in the capacitive measurement structure one by one, measure the to-be-measured capacitance corresponding to each capacitive measurement module, when the measurement resistance corresponding to each capacitive measurement module is two, connect the first branch and the first sub-branch to zero potential, switch the second sub-branch from high potential to low potential, and obtain the first potential change curve between the first branch and the third branch with time by leading out the signal of the third branch;

[0022] Step 22: obtain the value of the time constant RC based on the first change curve, and obtain the capacitance value of the first measurement capacitance C 测量1 through the second measurement resistance, wherein the second sub-branch, the third branch, the second measurement resistance, the to-be-measured capacitance C 待测 , the third capacitance unit, the parasitic capacitance C 寄生3 between the second sub-branch and the third branch and the first branch form an RC circuit;

[0023] Step 23: connect the third branch and the second sub-branch to zero potential, switch the first sub-branch from high potential to low potential, and obtain the second potential change curve between the first branch and the third branch with time by leading out the signal of the first branch;

[0024] Step 24: obtain the value of the time constant RC based on the second change curve, and obtain the capacitance value of the second measurement capacitance C 测量2 through the first measurement resistance, wherein the first sub-branch, the first branch, the first measurement resistance, the to-be-measured capacitance C 待测, the parasitic capacitance C between the first sub-branch and the first branch 寄生1 and the third branch form an RC circuit.

[0025] Step 25: the first branch and the first sub-branch are connected to zero potential, the third branch is switched from high potential to low potential, and the third change curve of the potential between the first sub-branch and the second sub-branch with time is obtained through the signal of the second sub-branch;

[0026] Step 26: based on the third change curve, the value of the time constant RC is obtained, and the capacitance value of the third measurement capacitance C 测量3 is obtained through the second measurement resistance, wherein the first sub-branch, the second sub-branch, the third branch, the second measurement resistance, the second capacitance unit, the third capacitance unit, the parasitic capacitance C 寄生2 between the first sub-branch and the second sub-branch, and the parasitic capacitance C 寄生3 between the second sub-branch and the third branch form an RC circuit.

[0027] Step 27: the third branch and the second sub-branch are connected to zero potential, the first branch is switched from high potential to low potential, and the fourth change curve of the potential between the first sub-branch and the second sub-branch with time is obtained through the signal of the first sub-branch;

[0028] Step 28: based on the fourth change curve, the value of the time constant RC is obtained, and the capacitance value of the third measurement capacitance C 测量4 is obtained through the first measurement resistance, wherein the first branch, the first sub-branch, the second sub-branch, the first measurement resistance, the first capacitance unit, the second capacitance unit, the parasitic capacitance C 寄生1 between the first sub-branch and the first branch, and the parasitic capacitance C 寄生2 between the first sub-branch and the second sub-branch form an RC circuit.

[0029] Step 29: the test equipment applies a signal to the first sub-branch and the second sub-branch, and obtains the capacitance value of the fifth measurement capacitance C 测量5 , and further based on steps 21 to 28, the capacitance value of the to-be-measured capacitance C 待测 is obtained, wherein

[0030] C 待测 = (C 测量5 + (C 测量1+ C 测量2 -C 测量3 -C 测量4 ) / 2) / 2.

[0031] As described above, the capacitance measurement structure and method of the present application has the following beneficial effects:

[0032] 1) The capacitor measurement structure and method of the present application, by setting a measurement resistance or a measurement resistance and capacitor unit between the plate of the capacitor to be measured and the branch, the capacitor to be measured and the branch form an RC circuit, and through the known measurement resistance, the capacitance value of the capacitor to be measured, which is usually less than picofarad level inside the wafer, is further measured.

[0033] 2) The capacitor measurement structure and method of the present application, simple structure, easy operation, wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The first structure schematic diagram of the capacitor measurement module of the present application is shown.

[0035] Figure 2 The equivalent circuit schematic diagram of the first structure of the capacitor measurement module in the capacitor measurement structure of the present application is shown.

[0036] Figure 3 The second structure schematic diagram of the capacitor measurement module of the present application is shown.

[0037] Figure 4 The equivalent circuit schematic diagram of the second structure of the capacitor measurement module of the present application is shown.

[0038] Figure 5 The first function flow schematic diagram of the capacitor measurement method of the present application is shown.

[0039] Figure 6 The second function flow schematic diagram of the capacitor measurement method of the present application is shown.

[0040] BRIEF DESCRIPTION OF DRAWINGS

[0041] 11 capacitor measurement module

[0042] 111 first branch

[0043] 112 second branch

[0044] 1121 first sub-branch

[0045] 1122 second sub-branch

[0046] 113 third branch

[0047] 114 first capacitor unit

[0048] 115 second capacitor unit

[0049] 116 third capacitor unit

[0050] S11-S13 steps

[0051] S21-S29 steps DETAILED DESCRIPTION

[0052] The present application is herein described, by way of example only, with the

[0053] Reference will now be made to the drawings, wherein: Figures 1 to 6 It is to be understood that the drawings are to be used only for illustrating purposes and that they are not to be construed as a limitation of the present application. The present application is portrayed in these drawings by way of example only and, as such, other embodiments of the present application can be used without departing from the spirit and scope of the present application. Additionally, the specific details of the present application can be varied greatly without departing from the spirit and scope of the present application. It is to be understood that the drawings are not to scale and are solely for purposes of illustration of the present application.

[0054] Embodiment 1

[0055] As shown in Figures 1 to 4 , the present application provides a capacitance measurement structure for measuring a to-be-measured capacitance inside a wafer, the capacitance measurement structure comprising:

[0056] As shown in Figure 1 and Figure 3 , N capacitance measurement modules 11 are arranged at intervals on the surface of the wafer, each capacitance measurement module 11 measuring a corresponding to-be-measured capacitance C 待测 , each capacitance measurement module 11 comprising a first branch 111, a second branch 112 and a third branch 113 arranged in sequence in a lateral direction or in a longitudinal direction, wherein the first branch 111 and the third branch 113 are connected to the upper and lower plates of the corresponding to-be-measured capacitance C 待测 , and N is a natural number greater than 1. It should be noted that the distribution of the N capacitance measurement modules 11 on the wafer is not shown in Figure 1 and Figure 3 , and specific arrangements will not be described here.

[0057] As shown in Figure 1 and Figure 3 , each capacitance measurement module 11 corresponds to at least one measurement resistor. Specifically, as an example, as shown in Figure 1 and Figure 3As shown, the measurement resistance is located on the surface of the wafer or inside the wafer. More specifically, when the measurement resistance is located on the surface of the wafer, the measurement resistance is a thin-film resistance or a patch resistance; when the measurement resistance is located inside the wafer, the measurement resistance is formed inside the wafer by etching. It should be noted that the thin-film resistance is made by evaporating a certain resistivity material on the surface of an insulating material, where the surface of the insulating material refers to the surface of the wafer, and the commonly used insulating material is a ceramic substrate. Further, the formation of the thin film is essentially a process of gas-solid conversion and crystal generation, which can be roughly divided into: ① atoms or molecules of gas collide with the surface of a solid; ② atoms or molecules of gas are adsorbed by atoms on the surface of the solid or directly emitted back into space; ③ the adsorbed particles migrate or diffuse on the surface of the solid and move to the appropriate lattice position on the surface and enter the lattice. This process and their mutual relationship determine the formation process of the thin film and the properties of the thin film. Generally speaking, a thin-film resistance contains at most three types of phase components: insulating phase, semiconductor phase and conductive phase. In existing thin-film resistances, these phases are often finely distributed, and some are distributed in molecular line. When the temperature coefficient and the accuracy requirement are high, the measurement resistance is usually a thin-film resistance. The patch resistance is a kind of metal glass enamel resistor, which is made by mixing metal powder and glass enamel powder and printing on the substrate by screen printing method. It has the advantages of high temperature resistance, moisture resistance, small temperature coefficient, and can greatly save circuit space cost, making the design more refined. When the measurement resistance is located inside the wafer, it usually becomes a wafer resistance. The wafer resistance adopts a cylindrical metal electrode leadless interface technology, which is called Metal Electrode Leadless Face (MELF for short) in English. The wafer resistance can be made smaller, more precise, and has good heat dissipation and temperature change resistance (from -55 degrees Celsius to +155 degrees Celsius), and can be used in harsh working environments.

[0058] It should be noted that the measurement resistance includes but is not limited to a thin-film resistance or a patch resistance or is formed inside the wafer, as long as it can form an RC circuit between the plate of the to-be-measured capacitor C 待测 and the branch, and then measure the to-be-measured capacitor C 待测 , and any position and setting form of the measurement resistance are applicable, and are not limited by the embodiment.

[0059] As shown in Figure 1 and Figure 2 , when the number of measurement resistances is one, as shown in Figure 1 , the measurement resistance R1 is connected to the to-be-measured capacitor C 待测the second branch 112 and the third branch 113; the first branch 111, the second branch 112 and the third branch 113 each include a pad, wherein the pad in the first branch 111 is PAD1, the pad in the second branch 112 is PAD2, and the pad in the third branch 113 is PAD3; the shapes and sizes of the pads are equal. Further, when the pads are arranged in the transverse direction, the top ends of the pads are flush; when the pads are arranged in the longitudinal direction, the left ends of the pads are flush. It should be noted that between PAD1 and PAD2, and between PAD2 and PAD3, there is an inevitable parasitic capacitance, the capacitance value of the parasitic capacitance is proportional to the cross-sectional area of the two pads (including PAD1 and PAD2, and PAD2 and PAD3) and inversely proportional to the distance between the two pads. In this embodiment, the distance between PAD1 and PAD2 is at least one-third smaller than the distance between PAD2 and PAD3, so that the parasitic capacitance C 寄生2 between PAD2 and PAD3 is smaller than the parasitic capacitance C 寄生1 between PAD1 and PAD2. By setting the distance, C 寄生2 is equivalent to one-third of the to-be-measured capacitance C 待测 , or even smaller, so that C 待测 can be ignored when measuring the to-be-measured capacitance C 寄生2 . It should be noted that when the number of measurement resistors is one, the equivalent circuit is as shown in Figure 2 .

[0060] As shown in Figure 3 and Figure 4 , when the number of measurement resistors is two, as shown in Figure 3 , the second branch 112 includes a first sub-branch 1121 and a second sub-branch 1122, a first measurement resistor R11 is connected between the upper plate of the to-be-measured capacitance C 待测 and the first sub-branch 1121, and a second measurement resistor R12 is connected between the lower plate of the to-be-measured capacitance C 待测 and the second sub-branch 1122; a first capacitance unit 114 is arranged between the first branch 111 and the first sub-branch 1121; a second capacitance unit 115 is arranged between the first sub-branch 1121 and the second sub-branch 1122; and a third capacitance unit 116 is arranged between the second sub-branch 1122 and the third branch 113. Specifically, as an example, as shown in Figure 3As shown, the interval between the first branch 111 and the first sub-branch 1121 is equal to the interval between the first sub-branch 1121 and the second sub-branch 1122; the interval between the first sub-branch 1121 and the second sub-branch 1122 is equal to the interval between the second sub-branch 1122 and the third branch 113. The first branch 111, the first sub-branch 1121, the second sub-branch 1122 and the third branch 113 all include a pad, and the shape and size of each pad are equal, wherein the pad in the first branch 111 is PAD1, the pad in the first sub-branch 1121 is PAD21, the pad in the second sub-branch 1122 is PAD22, and the pad in the third branch 113 is PAD3; as shown in Figure 4 the parasitic capacitance between PAD1 and PAD21 is C 寄生121 , the parasitic capacitance between PAD21 and PAD22 is C 寄生212 , and the parasitic capacitance between PAD22 and PAD3 is C 寄生223 Due to the equal intervals, C 寄生121 =C 寄生212 =C 寄生223 .

[0061] As shown in Figure 1 and Figure 3 , the to-be-measured capacitance C 待测 is measured by connecting the test equipment to the capacitance measurement structure 11. It should be noted that the resistance values of the first measurement resistor R11 and the second measurement resistor R12 can be equal or not equal, and the resistance values of the first measurement resistor R11 and the second measurement resistor R12 should be set according to the actual use scene, and further, the measurement resistor R1, the first measurement resistor R11 and the second measurement resistor R12 can be one resistor, or a plurality of resistors in series, or in parallel, or in a combination of series and parallel, and the specific setting should be made according to the actual use scene, which will not be described here.

[0062] Specifically, as shown in Figure 3 and Figure 4 , the first capacitance unit 114 includes a first capacitance C1, the second capacitance unit 115 includes a second capacitance C2, and the third capacitance unit 116 includes a third capacitance C3, wherein C1, C2 and C3 can be equal or not equal in capacitance value; C1, C2 and C3 can be one capacitance or a plurality of capacitors in series, or a plurality of capacitors in parallel, or a combination of series and parallel; C1, C2 and C3 can be set on the wafer surface or inside the wafer, and can be a thin film capacitor or a ceramic capacitor; C1, C2 and C3 should be set according to the actual use scene, which will not be described here.

[0063] Embodiment Two

[0064] As Figure 5 shown, the embodiment provides a capacitance measurement method for measuring a to-be-measured capacitance C 待测 inside a wafer, and the capacitance measurement method comprises:

[0065] S11: as Figure 5 shown, connect the test equipment with each capacitance measurement module 11 in the capacitance measurement structure in embodiment one, and measure the to-be-measured capacitance C 待测 corresponding to each capacitance measurement module 11, when the measurement resistance corresponding to each capacitance measurement module 11 is one, connect the first branch 111 in the capacitance measurement module 11 to zero potential, and connect the second branch 112 to high potential. It should be noted that, as Figure 1 and Figure 2 shown, the to-be-measured resistance R1 is connected with the second branch 112, and the resistance value of the to-be-measured resistance R1 can be measured through the second branch 112 and the third branch 113.

[0066] S12: as Figure 5 shown, keep the first branch 111 at zero potential, switch the second branch 112 from high potential to low potential, and obtain the potential change curve of the first branch 111 and the second branch 112 with time through the signal of the third branch 113. It should be noted that the change curve can be fitted into a specific waveform through an oscilloscope, and the value of the time constant RC can be obtained through the specific waveform. The time constant RC is used to reflect the time constant of the transition period when the circuit decays with time. If it is an RC circuit, the time constant is the product of the capacitance C and the resistance R; if it is an LR circuit, the time constant is the ratio of the capacitance L and the resistance R, and the unit of the time constant is second. Taking the RC circuit as an example, when a constant current I flows in the circuit, the maximum value of the end voltage of the capacitance C is the product of the current I and the resistance R, and the time required to reach(1-1 / e)or about 0.63 times the maximum end voltage is the time constant, which is usually represented by the product of the capacitance C and the resistance R. Therefore, in this embodiment, the value of the capacitance can be calculated based on the time constant through the known resistance, such as the to-be-measured resistance R1, and the value of the to-be-measured capacitance C 待测 is further obtained. It should be further noted that the potential change curve with time is obtained by the oscilloscope, and the oscilloscope is fitted to obtain the waveform of the RC loop.

[0067] S13: as Figure 5 shown, based on the potential change curve between the first branch 111 and the second branch 112, the value of the time constant RC is obtained, and the capacitance value of the to-be-measured capacitance C 待测 is further obtained through the measurement resistance R1, wherein the first branch 111, the to-be-measured capacitance C 待测 , the measurement resistance R1 and the second branch 112 form an RC loop.

[0068] It should be noted that the spacing between PAD1 and PAD2 is at least one-third smaller than the spacing between PAD2 and PAD3, thus reducing the parasitic capacitance C between PAD2 and PAD3. 寄生2 Compare the parasitic capacitance C between PAD1 and PAD2 寄生1 Small, by setting the spacing, make C 寄生2 Equivalent to the capacitor C under test 待测 One-third, or even less, of the capacitance C under test, thus making it possible to measure the capacitance C under test. 待测 When, make C 寄生2 This can be ignored; therefore, the capacitance C in the RC circuit only includes: the capacitance C under test. 待测 Parasitic capacitance C 寄生2 This can be ignored. Calculate the capacitance C to be measured. 待测 Theoretical basis: Assume the capacitance to be measured is C 待测 The initial voltage is V0. When the second branch 112 is connected to a high potential, the capacitor C under test... 待测 The voltage is V1, and the capacitor to be measured is C. 待测 The function value of time t is Vt, where Vt=V0+(V1-V0)*(1-e(-t / R*C)), then t=R*C*ln[(V1-V0) / (V1-Vt)]. Therefore, by fitting the potential change between PAD1 and PAD3, the capacitance C to be measured can be determined. 待测 The capacitance value.

[0069] Example 3

[0070] like Figure 6 As shown, this embodiment provides a capacitance measurement method for measuring the capacitance C inside a wafer. 待测 The capacitance measurement method includes:

[0071] S21: As Figure 6 As shown, the testing equipment is connected one by one to each of the capacitance measurement modules 11 in the capacitance measurement structure of Embodiment 1, and the capacitance C to be measured corresponding to each capacitance measurement module 11 is measured. 待测 When performing measurements, if each capacitance measurement module corresponds to two measuring resistors, such as... Figure 3 and Figure 4 As shown, each capacitance measurement module 11 includes two measuring resistors, namely a first measuring resistor R11 and a second measuring resistor R12. The first branch 111 and the first sub-branch 1121 are connected to zero potential, and the second sub-branch 1122 is switched from a high potential to a low potential. By extracting the signal from the third branch 113, the first potential change curve between the first branch 111 and the third branch 113 over time is obtained. It should be noted that the first change curve can be fitted into a specific waveform using an oscilloscope, and the value of the time constant RC can then be obtained from this specific waveform.

[0072] S22: As Figure 6 As shown, based on the first change curve, the value of the time constant RC is obtained, and the first measuring capacitance C is obtained through the second measuring resistor R12. 测量1 The capacitance value, where, for example Figure 4 As shown, the second sub-branch 1122, the third branch 113, the second measuring resistor R12, and the capacitor under test C are... 待测 The parasitic capacitance C between the third capacitor unit 116, the second sub-branch 1122, and the third branch 113. 寄生223 Together with the first branch 111, they form an RC circuit. The capacitor portion of the RC circuit includes the capacitor C to be measured. 待测 The third capacitor C3 and parasitic capacitor C in the third capacitor unit 116 寄生223 ,in,

[0073] C 测量1 =C 待测 +C3+C 寄生223 .

[0074] S23: As Figure 6 As shown, the third branch 113 and the second sub-branch 1122 are connected to zero potential, and the first sub-branch 1121 is switched from high potential to low potential. By extracting the signal from the first branch 111, a second potential change curve between the first branch 111 and the third branch 113 over time is obtained. It should be noted that the second change curve can be fitted into a specific waveform using an oscilloscope, and then the value of the time constant RC can be obtained from the specific waveform.

[0075] S24: As Figure 6 As shown, based on the second variation curve, the value of the time constant RC is obtained, and the second measuring capacitance C is obtained through the first measuring resistor R11. 测量2 The capacitance value, where, for example Figure 4 As shown, the first sub-branch 1121, the first branch 111, the first measuring resistor R11, and the capacitor under test C are shown. 待测 The parasitic capacitance C between the first capacitor unit 114, the first sub-branch 1121, and the first branch 111. 寄生121 The third branch forms an RC circuit, wherein the capacitor part of the RC circuit includes: the capacitor C to be measured. 待测 The third capacitor C1 and the parasitic capacitor C in the first capacitor unit 114 寄生121 ,in,

[0076] C 测量2 =C 待测 +C1+C 寄生121 .

[0077] S25: As Figure 6As shown, the first branch 111 and the first sub-branch 1121 are connected to zero potential, the third branch 113 is switched from high potential to low potential, and the signal of the second sub-branch 1122 is led out to obtain a third change curve of the potential between the first sub-branch and the second sub-branch with time. It should be noted that the third change curve can be fitted into a specific waveform through an oscilloscope, and then the value of the time constant RC is obtained through the specific waveform.

[0078] S26: As shown in the figure, Figure 6 the value of the time constant RC is obtained based on the third change curve, and the capacitance value of the third measurement capacitor C 测量3 is obtained through the second measurement resistor R12, wherein, as shown in the figure, Figure 4 the first sub-branch 1121, the second sub-branch 1122, the third branch 113, the second measurement resistor R12, the second capacitor unit 115, the third capacitor unit 116, the parasitic capacitance C 寄生212 between the first sub-branch 1121 and the second sub-branch 1122, and the parasitic capacitance C 寄生223 between the second sub-branch 1121 and the third branch 113 constitute an RC circuit, wherein the capacitance part in the RC circuit includes: the second capacitor C2 in the second capacitor unit 115, the third capacitor C3 in the third capacitor unit 116, the parasitic capacitance C 寄生212 , and the parasitic capacitance C 寄生223 , wherein,

[0079] C 测量3 =C2+C 寄生212 +C3+C 寄生223 .

[0080] S27: As shown in the figure, Figure 6 the third branch 113 and the second sub-branch 1122 are connected to zero potential, the first branch 111 is switched from high potential to low potential, and the signal of the first sub-branch 1121 is led out to obtain a fourth change curve of the potential between the first sub-branch 1121 and the second sub-branch 1122 with time. It should be noted that the fourth change curve can be fitted into a specific waveform through an oscilloscope, and then the value of the time constant RC is obtained through the specific waveform.

[0081] S28: As shown in the figure, Figure 6 the value of the time constant RC is obtained based on the fourth change curve, and the capacitance value of the third measurement capacitor C 测量4 is obtained through the first measurement resistor, wherein, as shown in the figure, Figure 4 the first branch 111, the first sub-branch 1121, the second sub-branch 1122, the first measurement resistor R11, the first capacitor unit 114, the second capacitor unit 115, the parasitic capacitance C 寄生121The parasitic capacitance C between the first sub-branch 1121 and the second sub-branch 1122 寄生212 The circuit comprises an RC circuit, wherein the capacitor portion of the RC circuit includes: the first capacitor C1 in the first capacitor unit 114, the third capacitor C2 in the second capacitor unit 115, and the parasitic capacitance C. 寄生121 Parasitic capacitance C 寄生212 ,in,

[0082] C 测量4 =C2+C 寄生212 +C1+C 寄生121 .

[0083] S29: As Figure 6 As shown, the test equipment applies signals to the first sub-branch 1121 and the second sub-branch 1122 to obtain the fifth measured capacitance C. 测量5 Based on the capacitance value, and further based on steps S21 to S28, the capacitance C to be tested is obtained. 待测 The capacitance value, where, for example Figure 4 As shown, the fifth measured capacitance C 测量5 Includes: the capacitor C under test 待测 The third capacitor C2 in the second capacitor unit 115, and the parasitic capacitance C between the first sub-branch 1121 and the second sub-branch 1122. 寄生212 C 测量5 =C 待测 +C2+C 寄生2 ,and then,

[0084] C 待测 =(C 测量5 +(C 测量1+ C 测量2 -C 测量3 -C 测量4 ) / 2) / 2.

[0085] The capacitive measurement structure and method of the present application at least comprises N capacitive measurement modules arranged at intervals on the surface of a wafer, each of the capacitive measurement modules measures a corresponding to-be-measured capacitor, each of the capacitive measurement modules comprises a first branch, a second branch and a third branch arranged in sequence along a transverse direction or a longitudinal direction, wherein the first branch and the third branch are connected to upper and lower plates of the corresponding to-be-measured capacitor respectively, and N is a natural number greater than 1; each of the capacitive measurement modules corresponds to at least one measurement resistor, when the number of measurement resistors is one, the measurement resistor is connected between the lower plate of the to-be-measured capacitor and the second branch; when the number of measurement resistors is two, the second branch comprises a first sub-branch and a second sub-branch, a first measurement resistor is connected between the upper plate of the to-be-measured capacitor and the first sub-branch, and a second measurement resistor is connected between the lower plate of the to-be-measured capacitor and the second sub-branch; a first capacitor unit is arranged between the first branch and the first sub-branch; a second capacitor unit is arranged between the first sub-branch and the second sub-branch; and a third capacitor unit is arranged between the second sub-branch and the third branch; wherein the to-be-measured capacitor is measured by connecting a test device to the capacitive measurement structure. The capacitive measurement structure and method of the present application set measurement resistors or measurement resistors and capacitor units between the plates of the to-be-measured capacitor and the branches, so that the to-be-measured capacitor and the branches form an RC circuit, and the capacitance of the to-be-measured capacitor inside the wafer, which is usually less than a picofarad level, is further measured by the known measurement resistors. The capacitive measurement structure and method of the present application have simple structure, convenient operation and wide application range. Therefore, the present application effectively overcomes the shortcomings of the prior art and has high industrial utilization value.

[0086] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought of the present application should be covered by the claims of the present application.

Claims

1. A capacitance measurement method for measuring a to-be-measured capacitance inside a wafer, characterized by, The capacitance measurement method at least comprises: Step 21: Connect the test equipment to each capacitance measurement module (11) in the capacitance measurement structure one by one, and measure the capacitance C to be tested corresponding to each capacitance measurement module (11). 待测 When performing measurements, if each capacitance measurement module (11) corresponds to two measuring resistors, the first branch (111) and the first sub-branch (1121) are connected to zero potential, and the second sub-branch (1122) is switched from high potential to low potential. By extracting the signal from the third branch (113), the first change curve of the potential between the first branch (111) and the third branch (113) over time is obtained. The capacitance measurement structure includes N capacitance measurement modules (11) spaced apart on the wafer surface. Each capacitance measurement module (11) measures one corresponding capacitance C to be measured. 待测 Each of the capacitance measurement modules (11) includes a first branch (111), a second branch (112), and a third branch (113) that are sequentially adjacent in the horizontal or vertical direction. The first branch (111) and the third branch (113) are respectively connected to the upper and lower plates of the capacitor C to be measured, and N is a natural number greater than 1. When there are two measuring resistors, the second branch (112) includes a first sub-branch (1121) and a second sub-branch (1122), and the first measuring resistor R11 is connected to the capacitor C to be measured. 待 The measuring resistor R12 is connected between the upper plate of the measuring device and the first sub-branch (1121), and the second measuring resistor R12 is connected to the capacitor C under test. 待测 Between the lower electrode plate and the second sub-branch (1122); a first capacitor unit (114) is provided between the first branch (111) and the first sub-branch (1121); a second capacitor unit (115) is provided between the first sub-branch (1121) and the second sub-branch (1122); a third capacitor unit (116) is provided between the second sub-branch (1122) and the third branch (113); Step 22: based on the first change curve, the value of the time constant RC is obtained, and the first measurement capacitor C is obtained through the second measurement resistance R12 测量1 , wherein the second sub-branch (1122), the third branch (113), the second measurement resistance R12, the to-be-measured capacitor C 待测 , the third capacitor unit (116), the parasitic capacitor C 寄生223 between the second sub-branch (1122) and the third branch (113) and the first branch (111) constitute an RC circuit; Step 23: connecting the third branch (113) with the second sub-branch (1122) to zero potential, switching the first sub-branch (1121) from high potential to low potential, obtaining the second change curve of the potential between the first branch (111) and the third branch (113) with time by leading out the signal of the first branch (111); Step 24: based on the second change curve, the value of the time constant RC is obtained, and the second measurement capacitor C is obtained through the first measurement resistor R11 测量2 , wherein the first sub-branch (1121), the first branch (111), the first measurement resistor R11, the to-be-measured capacitor C 待测 , the first capacitor unit (114), the parasitic capacitor C 寄生121 between the first sub-branch (1121) and the first branch (111) and the third branch (113) constitute an RC circuit; Step 25: connecting the first branch (111) with the first sub-branch (1121) to zero potential, switching the third branch (113) from high potential to low potential, obtaining the third change curve of the potential between the first sub-branch (1121) and the second sub-branch (1122) with time by leading out the signal of the second sub-branch (1122); Step 26: based on the third change curve, the value of the time constant RC is obtained, and the third measured capacitance C is obtained through the second measured resistance R12 测量3 , wherein the first sub-branch (1121), the second sub-branch (1122), the third branch (113), the second measured resistance R12, the second capacitance unit (115), the third capacitance unit (116), the parasitic capacitance C 寄生212 between the first sub-branch (1121) and the second sub-branch (1122), the parasitic capacitance C 寄生223 between the second sub-branch (1122) and the third branch (113) constitute an RC circuit; Step 27: connecting the third branch (113) with the second sub-branch (1122) to zero potential, switching the first branch (111) from high potential to low potential, obtaining the fourth change curve of the potential between the first sub-branch (1121) and the second sub-branch (1122) with time by leading out the signal of the first sub-branch (1121); Step 28: based on the fourth change curve, the value of the time constant RC is obtained, and the third measurement capacitance C is obtained through the first measurement resistance R11 测量4 , wherein the first branch (111), the first sub-branch (1121), the second sub-branch (1122), the first measurement resistance R11, the first capacitance unit (114), the second capacitance unit (115), the parasitic capacitance C 寄生121 between the first sub-branch (1121) and the second sub-branch (1122) constitute an RC circuit. 寄生212 ​ Step 29: the test device applies signals to the first sub-branch (1121) and the second sub-branch (1122) to obtain a fifth measured capacitance C 测量5 , further based on steps 21 to 28, to obtain a capacitance value of the to-be-measured capacitance C 待测 , where C 待测 = (C 测量5 + (C 测量1 + C 测量2 - C 测量3 - C 测量4 ) / 2) / 2.

2. The capacitance measurement method according to claim 1, characterized in that: The measurement resistance is located on the surface of the wafer or inside the wafer.

3. The method of claim 2, wherein: When the measurement resistance is located on the surface of the wafer, the measurement resistance is a thin film resistance or a patch resistance; when the measurement resistance is located inside the wafer, the measurement resistance is formed inside the wafer by etching.

4. The capacitance measurement method according to claim 2, characterized in that: The distance between the first branch (111) and the first sub-branch (1121) is equal to the distance between the first sub-branch (1121) and the second sub-branch (1122); the distance between the first sub-branch (1121) and the second sub-branch (1122) is equal to the distance between the second sub-branch (1122) and the third branch (113).

5. The method of claim 4, wherein: The first branch (111), the third branch (113), the first sub-branch (1121) and the second sub-branch (1122) each comprise a pad, and the shape and size of each pad are equal.

6. The method of claim 5, wherein: When each pad is arranged in the transverse direction, the top ends of each pad are flush; when each pad is arranged in the longitudinal direction, the left ends of each pad are flush.

Images