Test structure and test method

Abstract

The invention discloses a test structure and a test method. The two-dimensional material channel layer is suspended above the substrate; the laminated gate structure is located above the substrate, and the laminated gate structure comprises a bottom gate structure covering part of the bottom surface of the two-dimensional material channel layer and a top gate structure covering part of the top surface of the two-dimensional material channel layer; the drain region is positioned in the two-dimensional material channel layer on one side of the laminated gate structure; the source region is positioned in the two-dimensional material channel layer on the other side of the laminated gate structure; the first top surface contact electrode is positioned on the top surface of the drain region; the first bottom surface contact electrode is positioned on the bottom surface of the drain region; the second top surface contact electrode is located on the top surface of the source region, and the second top surface contact electrode is electrically connected with the top surface of the source region; and the second bottom surface contact electrode is located on the bottom surface of the source region, and the second bottom surface contact electrode is electrically connected with the bottom surface of the source region. The accuracy of obtaining the channel resistance value of the two-dimensional material channel layer is improved, and the performance of the test structure is further improved.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of semiconductor manufacturing, and in particular, to a test structure and a test method. Background Art

[0002] With the continuous advancement of Moore's Law, it has become increasingly difficult to continuously miniaturize the size of traditional silicon-based transistors, and the process technology is extremely difficult. At the same time, the short-channel effect introduced by size miniaturization and the adverse factors of dielectric tunneling will also increase the static power consumption of the device.

[0003] Two-dimensional semiconductor materials have an atomic-level thickness and are more easily regulated by an external electric field, and can reach a size smaller than the limit of silicon-based materials. Therefore, two-dimensional semiconductor materials are considered important materials for promoting the development of future integrated circuits.

[0004] Carrier mobility is an important parameter affecting device performance, and the channel resistance (R ch ) directly reflects the carrier mobility. Summary of the Invention

[0005] The problem solved by the embodiments of the present invention is to provide a test structure and a test method, which are beneficial to further improving the performance of the test structure.

[0006] To solve the above problems, embodiments of the present invention provide a test structure, including: a substrate; a two-dimensional material channel layer suspended above the substrate; a stacked gate structure located above the substrate, the stacked gate structure including a bottom gate structure covering a part of the bottom surface of the two-dimensional material channel layer and a top gate structure covering a part of the top surface of the two-dimensional material channel layer; a drain region located in the two-dimensional material channel layer on one side of the stacked gate structure; a source region located in the two-dimensional material channel layer on the other side of the stacked gate structure; a first top contact electrode located on the top surface of the drain region and electrically connected to the top surface of the drain region; a first bottom contact electrode located on the bottom surface of the drain region and electrically connected to the bottom surface of the drain region; a second top contact electrode located on the top surface of the source region and electrically connected to the top surface of the source region; a second bottom contact electrode located on the bottom surface of the source region and electrically connected to the bottom surface of the source region.

[0007] Optionally, the test structure further includes: a top gate contact electrode located on the top surface of the top gate structure; a bottom gate contact electrode located on the bottom surface of the bottom gate structure.

[0008] Optionally, the test structure further includes: an insulating layer located between the substrate and the stacked gate structure, between the substrate and the first bottom contact electrode, and between the substrate and the second bottom contact electrode.

[0009] Optionally, the first top surface contact electrode is used to apply a positive voltage, and the second top surface contact electrode is used to apply a zero potential.

[0010] Optionally, the material of the two-dimensional material channel layer includes transition metal chalcogenides.

[0011] Optionally, the substrate includes a dicing street area, and the test structure is located in the dicing street area.

[0012] Correspondingly, an embodiment of the present invention further provides a test method, including: providing the test structure provided by the embodiment of the present invention; applying corresponding test signals to the first top surface contact electrode and the second top surface contact electrode to form a test path through the first top surface contact electrode, the first bottom surface contact electrode, the two-dimensional material channel layer, the second top surface contact electrode, and the second bottom surface contact electrode; obtaining the channel resistance value of the two-dimensional material channel layer of the test path; obtaining the contact resistance value between the first top surface contact electrode and the drain region of the test path; obtaining the contact resistance value between the second top surface contact electrode and the source region of the test path.

[0013] Optionally, the step of applying corresponding test signals to the first top surface contact electrode and the second top surface contact electrode includes: applying a positive voltage to the first top surface contact electrode and applying a zero potential to the second top surface contact electrode.

[0014] Optionally, the step of obtaining the channel resistance value of the two-dimensional material channel layer of the test path includes: obtaining the first current value of the test path; after obtaining the first current value, measuring the first voltage value of the first bottom surface contact electrode; measuring the second voltage value of the second bottom surface contact electrode; obtaining the channel resistance value of the two-dimensional material channel layer through the first voltage value, the second voltage value, and the first current value.

[0015] Optionally, obtaining the channel resistance value R of the two-dimensional material channel layer ch =(V1 - V2) / I1, where V1 represents the first voltage value, V2 represents the second voltage value, and I1 represents the first current value.

[0016] Optionally, the step of obtaining the contact resistance between the first top surface contact electrode and the drain region of the test path includes: obtaining the first current value of the test path; after obtaining the first current value, measuring the third voltage value of the first top surface contact electrode; measuring the fourth voltage value of the first bottom surface contact electrode; obtaining the contact resistance between the first top surface contact electrode and the drain region through the first current value, the third voltage value, and the fourth voltage value.

[0017] Optionally, obtaining the contact resistance value R between the first top surface contact electrode and the drain region c1 =(V3 - V4) / I1, where V3 represents the third voltage value, V4 represents the fourth voltage value, and I1 represents the first current value.

[0018] Optionally, the steps of obtaining the contact resistance value between the second top surface contact electrode of the test path and the source region include: obtaining the first current value of the test path; after obtaining the first current value, measuring the fifth voltage value of the second top surface contact electrode; measuring the sixth voltage value of the second bottom surface contact electrode; obtaining the contact resistance between the second top surface contact electrode and the source region through the first current value, the fifth voltage value, and the sixth voltage value.

[0019] Optionally, obtaining the contact resistance value R between the second top surface contact electrode and the source region c2 =(V5 - V6) / I1, where V5 represents the fifth voltage value, V6 represents the sixth voltage value, and I1 represents the first current value.

[0020] Optionally, in the step of providing the test structure, the test structure further includes: a top gate contact electrode located on the top surface of the top gate structure; a bottom gate contact electrode located on the bottom surface of the bottom gate structure; in the step of applying corresponding test signals to the first top surface contact electrode and the second top surface contact electrode, voltage signals are further applied to the top gate contact electrode and the bottom gate contact electrode to make the two-dimensional material channel layer between the drain region and the source region in a conducting state.

[0021] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0022] An embodiment of the present invention provides a test structure. The stacked gate structure is located above the substrate. The stacked gate structure includes a bottom gate structure covering a part of the bottom surface of the two-dimensional material channel layer and a top gate structure covering a part of the top surface of the two-dimensional material channel layer. The drain region is located in the two-dimensional material channel layer on one side of the stacked gate structure, and the source region is located in the two-dimensional material channel layer on the other side of the stacked gate structure. The first top contact electrode is located on the top surface of the drain region and is electrically connected to the top surface of the drain region. The first bottom contact electrode is located on the bottom surface of the drain region and is electrically connected to the bottom surface of the drain region. The second top contact electrode is located on the top surface of the source region and is electrically connected to the top surface of the source region. The second bottom contact electrode is located on the bottom surface of the source region and is electrically connected to the bottom surface of the source region. After applying test signals to the first top contact electrode and the second top contact electrode subsequently, it can make the first top contact electrode, the first bottom contact electrode, the two-dimensional material channel layer, the second top contact electrode, and the second bottom contact electrode form a test path, and obtain the current value of the test path. By setting the first bottom contact electrode on the bottom surface of the drain region and the second bottom contact electrode on the bottom surface of the source region, the voltage value of the two-dimensional material channel layer itself can be directly obtained, so as to obtain the channel resistance value of the two-dimensional material channel layer itself according to the voltage value and the current value, excluding the influence of the contact resistance value between the first top contact electrode and the drain region and the contact resistance value between the second top contact electrode and the source region on the channel resistance value, improving the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer, and further improving the performance of the test structure.

[0023] An embodiment of the present invention provides a test method. After applying test signals to the first top contact electrode and the second top contact electrode, it can make the first top contact electrode, the first bottom contact electrode, the two-dimensional material channel layer, the second top contact electrode, and the second bottom contact electrode form a test path, and obtain the current value of the test path. By setting the first bottom contact electrode on the bottom surface of the drain region and the second bottom contact electrode on the bottom surface of the source region, the voltage value of the two-dimensional material channel layer itself can be directly obtained, so as to obtain the channel resistance value of the two-dimensional material channel layer itself according to the voltage value and the current value, excluding the influence of the contact resistance value between the first top contact electrode and the drain region and the contact resistance value between the second top contact electrode and the source region on the channel resistance value, improving the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer, and further improving the performance of the test structure. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram corresponding to an embodiment of the test structure of the present invention;

[0025] Figure 2 is a flowchart of the steps of an embodiment of the test method of the present invention. Detailed Embodiments

[0026] As can be seen from the background, the carrier mobility is an important parameter affecting the device performance. Currently, during the measurement of the channel resistance R ch , by applying a fixed voltage V ds to the drain region and changing the voltage value of the gate structure to obtain different currents I, the corresponding total resistance R total under different gate voltage values can be obtained. And it is default that the contact resistance R c between the metal electrode and the source / drain doped regions remains unchanged. Thus, based on the total resistance R total minus the contact resistance R c , R ch can be obtained.

[0027] Through research, it is found that under different gate voltage values, the potential barrier difference between the source / drain doped regions and the metal electrode will change, resulting in different contact resistances Rc between the source / drain doped regions and the metal electrode. Therefore, the existing default that the contact resistance R c between the metal electrode and the source / drain doped regions remains unchanged will lead to a low accuracy in obtaining the channel resistance R ch .

[0028] To solve the technical problem, an embodiment of the present invention provides a test structure, including: a substrate; a two-dimensional material channel layer suspended above the substrate; a stacked gate structure located above the substrate, the stacked gate structure including a bottom gate structure covering a part of the bottom surface of the two-dimensional material channel layer and a top gate structure covering a part of the top surface of the two-dimensional material channel layer; a drain region located in the two-dimensional material channel layer on one side of the stacked gate structure; a source region located in the two-dimensional material channel layer on the other side of the stacked gate structure; a first top contact electrode located on the top surface of the drain region and electrically connected to the top surface of the drain region; a first bottom contact electrode located on the bottom surface of the drain region and electrically connected to the bottom surface of the drain region; a second top contact electrode located on the top surface of the source region and electrically connected to the top surface of the source region; a second bottom contact electrode located on the bottom surface of the source region and electrically connected to the bottom surface of the source region.

[0029] An embodiment of the present invention provides a test structure. The stacked gate structure is located above the substrate. The stacked gate structure includes a bottom gate structure covering a part of the bottom surface of the two-dimensional material channel layer and a top gate structure covering a part of the top surface of the two-dimensional material channel layer. The drain region is located in the two-dimensional material channel layer on one side of the stacked gate structure, and the source region is located in the two-dimensional material channel layer on the other side of the stacked gate structure. The first top contact electrode is located on the top surface of the drain region and is electrically connected to the top surface of the drain region. The first bottom contact electrode is located on the bottom surface of the drain region and is electrically connected to the bottom surface of the drain region. The second top contact electrode is located on the top surface of the source region and is electrically connected to the top surface of the source region. The second bottom contact electrode is located on the bottom surface of the source region and is electrically connected to the bottom surface of the source region. After applying test signals to the first top contact electrode and the second top contact electrode subsequently, it can make the first top contact electrode, the first bottom contact electrode, the two-dimensional material channel layer, the second top contact electrode, and the second bottom contact electrode form a test path, and obtain the current value of the test path. By providing the first bottom contact electrode on the bottom surface of the drain region and the second bottom contact electrode on the bottom surface of the source region, the voltage value of the two-dimensional material channel layer itself can be directly obtained, so as to obtain the channel resistance value of the two-dimensional material channel layer itself according to the voltage value and the current value, excluding the influence of the contact resistance value between the first top contact electrode and the drain region and the contact resistance value between the second top contact electrode and the source region on the channel resistance value, improving the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer, and further improving the performance of the test structure.

[0030] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings.

[0031] Figure 1 It is a schematic structural diagram corresponding to an embodiment of the test structure of the present invention.

[0032] The test structure includes: a substrate 100; a two-dimensional material channel layer 112 suspended above the substrate 100; a stacked gate structure 160 located above the substrate 100, the stacked gate structure 160 including a bottom gate structure 170 covering a part of the bottom surface of the two-dimensional material channel layer 112, and a top gate structure 106 covering a part of the top surface of the two-dimensional material channel layer 112; a drain region 191 in the two-dimensional material channel layer 112 on one side of the stacked gate structure 160; a source region 190 in the two-dimensional material channel layer 112 on the other side of the stacked gate structure 160; a first top contact electrode 110 located on the top surface of the drain region 191, and the first top contact electrode 110 is electrically connected to the top surface of the drain region 191; a first bottom contact electrode 111 located on the bottom surface of the drain region 191, and the first bottom contact electrode 111 is electrically connected to the bottom surface of the drain region 191; a second top contact electrode 102 located on the top surface of the source region 190, and the second top contact electrode 102 is electrically connected to the top surface of the source region 190; a second bottom contact electrode 103 located on the bottom surface of the source region 190, and the second bottom contact electrode 103 is electrically connected to the bottom surface of the source region 190.

[0033] It should be noted that after applying test signals to the first top contact electrode 110 and the second top contact electrode 102 subsequently, the first top contact electrode 110, the first bottom contact electrode 111, the two-dimensional material channel layer 112, the second top contact electrode 102, and the second bottom contact electrode 103 can form a test path, and the current value of the test path can be obtained. By providing the first bottom contact electrode 111 on the bottom surface of the drain region 191 and the second bottom contact electrode 103 on the bottom surface of the source region 190, the voltage value of the two-dimensional material channel layer 112 itself can be directly obtained, so that the channel resistance value of the two-dimensional material channel layer 112 itself can be obtained based on the voltage value and the current value, excluding the influence of the contact resistance value between the first top contact electrode 110 and the drain region 191 and the contact resistance value between the second top contact electrode 102 and the source region 190 on the channel resistance value, improving the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer 112, and further improving the performance of the test structure.

[0034] The substrate 100 provides a process platform for setting up the test structure.

[0035] In this embodiment, the substrate 100 is a silicon substrate. In other embodiments, the material of the substrate can also be other materials such as germanium, silicon germanide, silicon carbide, gallium arsenide, or indium gallium, and the substrate can also be other types of substrates such as a silicon-on-insulator substrate or a germanium-on-insulator substrate.

[0036] In this embodiment, the substrate 100 includes a dicing street region (not labeled).

[0037] Specifically, the dicing street area is the dicing area when the wafer is undergoing the dicing process, reducing the probability of damage to the chip area.

[0038] As an example, the test structure is located in the dicing street area.

[0039] In this embodiment, the test structure further includes: an insulating layer 101, located between the substrate 100 and the stacked gate structure 160, between the substrate 100 and the first bottom contact electrode 111, and between the substrate 100 and the second bottom contact electrode 103.

[0040] Specifically, the insulating layer 101 is used to electrically isolate between the stacked gate structure 160 and the substrate 100, between the first bottom contact electrode 111 and the substrate 100, and between the second bottom contact electrode 103 and the substrate 100, reducing the probability of leakage current in the substrate 100, thereby improving the performance of the test structure.

[0041] The material of the insulating layer 101 is a dielectric material. Specifically, the dielectric material includes one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and silicon carbonitride. As an example, the material of the insulating layer 101 is silicon oxide.

[0042] It should be noted that the thickness of the insulating layer 101 should not be too large or too small. If the thickness of the insulating layer 101 is too large, it is likely to cause the overall thickness of the test structure to be too large, which is not conducive to further reducing the overall size of the test structure. If the thickness of the insulating layer 101 is too small, it is likely to affect the electrical isolation function of the insulating layer 101, increasing the probability of breakdown of the insulating layer 101, thereby affecting the performance of the test structure. Therefore, in this embodiment, the thickness of the insulating layer 101 is 10 nanometers to 100 nanometers.

[0043] Specifically, the two-dimensional material channel layer 112 is used to provide a conductive channel for the transistor.

[0044] As an example, the material of the two-dimensional material channel layer 112 includes transition metal dichalcogenides (TMD).

[0045] Specifically, the transition metal dichalcogenide has an atomic-level thickness and is more easily regulated by an external electric field, and can reach a size smaller than that of silicon-based materials, which is beneficial to further reducing the size of the test structure, reducing the area of the dicing street occupied by the test structure. At the same time, the surface of the two-dimensional material is smooth and has no dangling bonds, and the contact surface with the stacked gate structure 160 has almost no defect trap parameters for electron scattering to affect the carrier mobility.

[0046] As an example, the material of the two-dimensional material channel layer 112 includes MoS2 or WS2.

[0047] The leakage region 191 and the source region 190 are used to provide mobile carriers for the conductive channel.

[0048] Specifically, when the transistor is a P-type transistor, the material of the stress layer is Si or SiGe, and the doping ions in the leakage region 191 and the source region 190 are P-type ions; when the transistor is an N-type transistor, the material of the stress layer is Si or SiC, and the doping ions in the leakage region 191 and the source region 190 are N-type ions.

[0049] The stacked gate structure 160 is used to control the opening and closing of the conductive channel when the device is operating.

[0050] In this embodiment, the stacked gate structure 160 is located above the substrate 100. The stacked gate structure 160 includes a bottom gate structure 170 covering a part of the bottom surface of the two-dimensional material channel layer 112, and a top gate structure 106 covering a part of the top surface of the two-dimensional material channel layer 112.

[0051] Specifically, the bottom gate structure 170 and the top gate structure 106 share the same two-dimensional material channel layer 112, which is beneficial to further reducing the overall size of the test structure. At the same time, by setting the bottom gate structure 170, the bottom gate structure 170 can control the opening of the conductive channel. In the subsequent process of obtaining the voltage value of the two-dimensional material channel layer 112 itself by using the first bottom contact electrode 111 and the second bottom contact electrode 103, the obtained voltage value can be the voltage value of the two-dimensional material channel layer 112 itself, thereby making the accuracy of the channel resistance value of the two-dimensional material channel layer 112 higher.

[0052] In this embodiment, both the bottom gate structure 170 and the top gate structure 106 include a gate dielectric layer 105 covering the two-dimensional material channel layer 112, and a gate electrode layer 104 covering the gate dielectric layer 105.

[0053] Specifically, the gate dielectric layer 105 includes a gate oxide layer covering the two-dimensional material channel layer 112, and a high-k gate dielectric layer 105 covering the gate oxide layer. Among them, the material of the high-k gate dielectric layer 105 is a high-k dielectric material, and the high-k dielectric material refers to a dielectric material whose relative dielectric constant is greater than that of silicon oxide.

[0054] As an example, the material of the gate dielectric layer 105 includes one or more of HfO2, ZrO2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, Al2O3, SiO2, and La2O3.

[0055] The gate electrode layer 104 is used for electrical connection with external structures (such as the top gate contact electrode and the bottom gate contact electrode). The material of the gate electrode layer 104 includes one or more of TiN, TaN, Ta, Ti, TiAl, W, Al, TiSiN, and TiAlC. Specifically, the gate electrode layer 104 may include a work function layer and an electrode layer covering the work function layer, or the gate electrode layer 104 may only include a work function layer.

[0056] In this embodiment, the test structure further includes: an interlayer dielectric layer 108, covering the sidewalls of the bottom gate structure 170 and the top gate structure 106.

[0057] Specifically, the interlayer dielectric layer 108 is used for electrically isolating the stacked gate structure 160 from the first top surface contact electrode 110, the first bottom surface contact electrode 111, the second top surface contact electrode 102, and the second bottom surface contact electrode 103.

[0058] The material of the interlayer dielectric layer 108 is a dielectric material. Specifically, the dielectric material includes one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and silicon carbonitride. As an example, the material of the interlayer dielectric layer 108 is silicon oxide.

[0059] In this embodiment, the test structure further includes: a top gate contact electrode 107, located on the top surface of the top gate structure 106; a bottom gate contact electrode 121, located on the bottom surface of the bottom gate structure 170.

[0060] Specifically, the top gate contact electrode 107 and the bottom gate contact electrode 121 are used for electrical connection with an external circuit structure, so that a voltage signal can be applied to the top gate contact electrode 107 and the bottom gate contact electrode 121 through the external circuit structure, enabling the two-dimensional material channel layer 112 between the drain region 191 and the source region 190 to be in a conductive (i.e., on) state.

[0061] In this embodiment, the materials of both the top gate contact electrode 107 and the bottom gate contact electrode 121 are tungsten.

[0062] It should be noted that tungsten has a low resistivity, which is beneficial for reducing the resistance values generated by the top gate contact electrode 107 and the bottom gate contact electrode 121. At the same time, tungsten has a fast electron mobility and high electrical conductivity, thus improving the performance of the test structure.

[0063] Specifically, the first top surface contact electrode 110 and the second top surface contact electrode 102 are used for electrical connection with an external circuit structure, so that a test signal can be applied to the first top surface contact electrode 110 and the second top surface contact electrode 102, enabling carriers to freely migrate in the two-dimensional material channel layer 112 between the drain region 191 and the source region 190.

[0064] In this embodiment, the first top surface contact electrode 110 is used to apply a positive voltage, and the second top surface contact electrode 102 is used to apply a zero potential.

[0065] Specifically, the first top surface contact electrode 110 is used to apply a positive voltage, and the second top surface contact electrode 102 is used to apply a zero potential, so as to generate a voltage difference between the first top surface contact electrode 110 and the second top surface contact electrode 102, and to form a test path by the first top surface contact electrode 110, the first bottom surface contact electrode 111, the two-dimensional material channel layer 112, the second top surface contact electrode 102, and the second bottom surface contact electrode 103, so that the current value of the test path can be obtained, and this current value is the current value generated by the two-dimensional material channel layer 112 under the voltage difference.

[0066] In this embodiment, the materials of the first top surface contact electrode 110 and the second top surface contact electrode 102 are both tungsten.

[0067] It should be noted that tungsten has a low resistivity, which is beneficial to making the resistance values generated by the first top surface contact electrode 110 and the second top surface contact electrode 102 relatively low, so as to reduce the influence of the resistance values generated by the first top surface contact electrode 110 and the second top surface contact electrode 102 on the test results and improve the accuracy of obtaining the channel resistance. At the same time, tungsten has a fast electron mobility and high conductivity, thus improving the performance of the test structure.

[0068] Specifically, by setting the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103, during the subsequent test of the test structure, by measuring the voltage values of the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103 respectively, the voltage value across the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103 is obtained, and this voltage value is the voltage value of the two-dimensional material channel layer 112 itself. Then, using this voltage value and the current value in the test path, the channel resistance value of the two-dimensional material channel layer 112 itself is obtained.

[0069] It should be noted that a contact resistance will be generated between the first top surface contact electrode 110 and the drain region 191, and a contact resistance will be generated between the second top surface contact electrode 102 and the source region 190. That is to say, a voltage division will occur between the first top surface contact electrode 110 and the drain region 191, and between the second top surface contact electrode 102 and the source region 190. Therefore, by measuring the voltage values of the first bottom surface contact electrode 111 at the bottom surface of the drain region 191 and the second bottom surface contact electrode 103 at the bottom surface of the source region 190, the risk that the voltage value accuracy of the two-dimensional material channel layer 112 itself is not high due to voltage division is avoided. That is to say, the influence of the contact resistance values between the first top surface contact electrode 110 and the drain region 191, and between the second top surface contact electrode 102 and the source region 190 on the channel resistance value is excluded, and the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer 112 is improved, thereby improving the performance of the test structure.

[0070] It should also be noted that the first top surface contact electrode 110 is provided on the top surface of the drain region 191, and the first bottom surface contact electrode 111 is provided on the bottom surface of the drain region 191. During the subsequent testing of the test structure, by measuring the voltage value between the first top surface contact electrode 110 and the first bottom surface contact electrode 111, and the current value of the obtained test path, the contact resistance between the first top surface contact electrode 110 and the drain region 191 can be obtained by using the current value and the voltage value. Similarly, the contact resistance between the second top surface contact electrode 102 and the source region 190 can also be obtained.

[0071] That is to say, the test structure can not only obtain the channel resistance value of the two-dimensional material channel layer 112, but also obtain the contact resistance between the first top surface contact electrode 110 and the drain region 191, and the contact resistance between the second top surface contact electrode 102 and the source region 190, enabling the same test structure to simultaneously meet different test requirements, thereby reducing the area of the scribe line occupied by the test structure and improving the performance of the test structure.

[0072] As an example, in this embodiment, the materials of the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103 are both tungsten.

[0073] It should be noted that tungsten has a low resistivity, which is beneficial to making the resistance values generated by the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103 themselves relatively low, so as to reduce the influence of the resistance values generated by the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103 themselves on the test results and improve the accuracy of obtaining the channel resistance value and the contact resistance value. At the same time, tungsten has a fast electron mobility and high electrical conductivity, thereby improving the performance of the test structure.

[0074] Correspondingly, the present invention also provides a test method. Figure 2It is a flowchart of the steps of an embodiment of the test method of the present invention.

[0075] In this embodiment, the test method includes the following basic steps:

[0076] Step S1: Provide the test structure provided in the foregoing embodiment;

[0077] Step S2: Apply corresponding test signals to the first top surface contact electrode and the second top surface contact electrode to form a test path with the first top surface contact electrode, the first bottom surface contact electrode, the two-dimensional material channel layer, the second top surface contact electrode, and the second bottom surface contact electrode;

[0078] Step S3: Obtain the channel resistance value of the two-dimensional material channel layer of the test path;

[0079] Step S4: Obtain the contact resistance value between the first top surface contact electrode of the test path and the drain region;

[0080] Step S5: Obtain the contact resistance value between the second top surface contact electrode of the test path and the source region.

[0081] An embodiment of the present invention provides a test method. After applying test signals to the first top surface contact electrode and the second top surface contact electrode, it can form a test path with the first top surface contact electrode, the first bottom surface contact electrode, the two-dimensional material channel layer, the second top surface contact electrode, and the second bottom surface contact electrode, and obtain the current value of the test path. By setting the first bottom surface contact electrode on the bottom surface of the drain region and the second bottom surface contact electrode on the bottom surface of the source region, the voltage value of the two-dimensional material channel layer itself can be directly obtained, so that the channel resistance value of the two-dimensional material channel layer itself can be obtained according to the voltage value and the current value, excluding the influence of the contact resistance value between the first top surface contact electrode and the drain region and the contact resistance value between the second top surface contact electrode and the source region on the channel resistance value, improving the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer, and further improving the performance of the test structure.

[0082] To make the above objects, features, and advantages of the embodiments of the present invention more obvious and understandable, the following Figure 1 makes a detailed description of the specific embodiments of the present invention.

[0083] Refer to Figure 1 , and execute step S1: Provide the test structure provided in the foregoing embodiment.

[0084] For the detailed description of the foregoing embodiments of the invention, refer to the description of the test structure, which will not be elaborated here.

[0085] In this embodiment, the test structure further includes: a top gate contact electrode 107 located on the top surface of the top gate structure 106; a bottom gate contact electrode 121 located on the bottom surface of the bottom gate structure 170.

[0086] Specifically, the top gate contact electrode 107 and the bottom gate contact electrode 121 are used for electrically connecting with an external circuit structure, so that a voltage signal can be applied to the top gate contact electrode 107 and the bottom gate contact electrode 121 through the external circuit structure, enabling the two-dimensional material channel layer 112 between the drain region 191 and the source region 190 to be in a conducting (i.e., turned-on) state.

[0087] In this embodiment, the materials of the top gate contact electrode 107 and the bottom gate contact electrode 121 are both tungsten.

[0088] It should be noted that tungsten has a low resistivity, which is beneficial for the top gate contact electrode 107 and the bottom gate contact electrode 121 to generate a low resistance value. At the same time, tungsten has a fast electron mobility and high electrical conductivity, thereby improving the performance of the test structure.

[0089] Reference Figure 1 , perform step S2: Apply corresponding test signals to the first top surface contact electrode 110 and the second top surface contact electrode 102, which is used to form a test path by the first top surface contact electrode 110, the first bottom surface contact electrode 111, the two-dimensional material channel layer 112, the second top surface contact electrode 102, and the second bottom surface contact electrode 103.

[0090] It should be noted that by applying corresponding test signals to the first top surface contact electrode 110 and the second top surface contact electrode 102, a test path is formed by the first top surface contact electrode 110, the first bottom surface contact electrode 111, the two-dimensional material channel layer 112, the second top surface contact electrode 102, and the second bottom surface contact electrode 103, which is beneficial for obtaining the first current value of the test path subsequently.

[0091] In this embodiment, the step of applying corresponding test signals to the first top surface contact electrode 110 and the second top surface contact electrode 102 includes: applying a positive voltage to the first top surface contact electrode 110 and applying a zero potential to the second top surface contact electrode 102.

[0092] Specifically, the first top surface contact electrode 110 is used to apply a positive voltage, and the second top surface contact electrode 102 is used to apply a zero potential, so as to generate a voltage difference between the first top surface contact electrode 110 and the second top surface contact electrode 102, and form a test path by the first top surface contact electrode 110, the first bottom surface contact electrode 111, the two-dimensional material channel layer 112, the second top surface contact electrode 102, and the second bottom surface contact electrode 103, thereby enabling the current value of the test path to be obtained, and this current value is the current value generated by the two-dimensional material channel layer 112 under the voltage difference.

[0093] In this embodiment, in the step of applying corresponding test signals to the first top surface contact electrode 110 and the second top surface contact electrode 102, a voltage signal is also applied to the top gate contact electrode 107 and the bottom gate contact electrode 121 to make the two-dimensional material channel layer 112 between the drain region 191 and the source region 190 in a conducting state.

[0094] Specifically, the top gate contact electrode 107 and the bottom gate contact electrode 121 are used to be electrically connected to an external circuit structure, so that a voltage signal can be applied to the top gate contact electrode 107 and the bottom gate contact electrode 121 through the external circuit structure, enabling the two-dimensional material channel layer 112 between the drain region 191 and the source region 190 to be in a conducting (i.e., turned-on) state.

[0095] Reference Figure 1 , perform step S3: Obtain the channel resistance value of the two-dimensional material channel layer 112 of the test path.

[0096] Specifically, the channel resistance value directly reflects the carrier mobility. By obtaining the channel resistance value of the two-dimensional material channel layer 112, the performance of the carrier mobility in the two-dimensional material channel layer 112 can be judged.

[0097] In this embodiment, the step of obtaining the channel resistance value of the two-dimensional material channel layer 112 of the test path includes: obtaining the first current value of the test path; after obtaining the first current value, measuring the first voltage value of the first bottom surface contact electrode 111; measuring the second voltage value of the second bottom surface contact electrode 103; and obtaining the channel resistance value of the two-dimensional material channel layer 112 through the first voltage value, the second voltage value, and the first current value.

[0098] In this embodiment, the step of obtaining the first current value of the test path includes: measuring the first current value of the test path through a current value measurement.

[0099] It should be noted that by separately measuring the voltage values of the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103, the voltage value across the first bottom surface contact electrode 111 and the second bottom surface contact electrode 103 is obtained, and this voltage value is the voltage value of the two-dimensional material channel layer 112 itself. Then, using this voltage value and the current value in the test path, the channel resistance value of the two-dimensional material channel layer 112 itself is obtained.

[0100] It should also be noted that contact resistance will be generated between the first top surface contact electrode 110 and the drain region 191, and between the second top surface contact electrode 102 and the source region 190. That is to say, voltage division will occur between the first top surface contact electrode 110 and the drain region 191, and between the second top surface contact electrode 102 and the source region 190. Therefore, by measuring the voltage values of the first bottom surface contact electrode 111 on the bottom surface of the drain region 191 and the second bottom surface contact electrode 103 on the bottom surface of the source region 190, the risk that the voltage value accuracy of the two-dimensional material channel layer 112 is not high due to voltage division is avoided. That is to say, the influence of the contact resistance values between the first top surface contact electrode 110 and the drain region 191, and between the second top surface contact electrode 102 and the source region 190 on the channel resistance value is excluded, improving the accuracy of obtaining the channel resistance value of the two-dimensional material channel layer 112, and thus improving the performance of the test structure.

[0101] As an example, the channel resistance value R of the two-dimensional material channel layer 112 is obtained ch =(V1 - V2) / I1, where V1 represents the first voltage value, V2 represents the second voltage value, and I1 represents the first current value.

[0102] Reference Figure 1 , perform step S4: Obtain the contact resistance value between the first top surface contact electrode 110 and the drain region 191 of the test path.

[0103] Specifically, by obtaining the contact resistance value between the first top surface contact electrode 110 and the drain region 191, the device performance of the transistor is judged.

[0104] In this embodiment, the steps of obtaining the contact resistance value between the first top surface contact electrode 110 and the drain region 191 of the test path include: obtaining the first current value of the test path; after obtaining the first current value, measuring the third voltage value of the first top surface contact electrode 110; measuring the fourth voltage value of the first bottom surface contact electrode 111; and obtaining the contact resistance value between the first top surface contact electrode 110 and the drain region 191 through the first current value, the third voltage value, and the fourth voltage value.

[0105] It should be noted that the first top surface contact electrode 110 is provided on the top surface of the drain region 191, and the first bottom surface contact electrode 111 is provided on the bottom surface of the drain region 191. During the test of the test structure, by measuring the voltage value between the first top surface contact electrode 110 and the first bottom surface contact electrode 111, and the current value of the obtained test path, the contact resistance between the first top surface contact electrode 110 and the drain region 191 can be obtained by using the current value and the voltage value.

[0106] It should also be noted that the test structure can not only obtain the channel resistance value of the two-dimensional material channel layer 112, but also obtain the contact resistance between the first top surface contact electrode 110 and the drain region 191, enabling the same test structure to meet different test requirements simultaneously, thereby reducing the area of the scribe line occupied by the test structure and improving the performance of the test structure.

[0107] As an example, obtain the contact resistance value R between the first top surface contact electrode 110 and the drain region 191 c1 =(V3 - V4) / I1, where V3 represents the third voltage value, V4 represents the fourth voltage value, and I1 represents the first current value.

[0108] Reference Figure 1 , perform step S5: Obtain the contact resistance value between the second top surface contact electrode 102 of the test path and the source region 190.

[0109] Specifically, by obtaining the contact resistance value between the second top surface contact electrode 102 and the source region 190, the device performance of the transistor is judged.

[0110] In this embodiment, the steps of obtaining the contact resistance value between the second top surface contact electrode 102 of the test path and the source region 190 include: obtaining the first current value of the test path; after obtaining the first current value, measuring the fifth voltage value of the second top surface contact electrode 102; measuring the sixth voltage value of the second bottom surface contact electrode 103; and obtaining the contact resistance value between the second top surface contact electrode 102 and the source region 190 through the first current value, the fifth voltage value, and the sixth voltage value.

[0111] It should be noted that the second top surface contact electrode 102 is provided on the top surface of the source region 190, and the second bottom surface contact electrode 103 is provided on the bottom surface of the source region 190. During the test of the test structure, by measuring the voltage value between the second top surface contact electrode 102 and the second bottom surface contact electrode 103, and the current value of the obtained test path, the contact resistance between the second top surface contact electrode 102 and the source region 190 can be obtained by using the current value and the voltage value.

[0112] It should also be noted that the test structure can not only obtain the channel resistance value of the two-dimensional material channel layer 112, but also obtain the contact resistance between the second top surface contact electrode 102 and the source region 190, enabling the same test structure to meet different test requirements simultaneously, thereby reducing the area of the scribe line occupied by the test structure and improving the performance of the test structure.

[0113] As an example, obtain the contact resistance value R between the second top surface contact electrode 102 and the source region 190 c2=(V5 - V6) / I1, where V5 represents the fifth voltage value, V6 represents the sixth voltage value, and I1 represents the first current value.

[0114] It should be noted that there is no specific order for the steps of obtaining the channel resistance value of the two-dimensional material channel layer 112, the step of obtaining the contact resistance value between the first top contact electrode 110 and the drain region 191, and the step of obtaining the contact resistance value between the second top contact electrode 102 and the source region 190. The order of each test step can be controlled according to specific test requirements.

[0115] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the claims.

Claims

1. A test structure, characterized in that, Comprising: A substrate; A two-dimensional material channel layer, suspended above the substrate; A stacked gate structure, located above the substrate, the stacked gate structure comprising a bottom gate structure covering a part of the bottom surface of the two-dimensional material channel layer, and a top gate structure covering a part of the top surface of the two-dimensional material channel layer; A drain region, located in the two-dimensional material channel layer on one side of the stacked gate structure; A source region, located in the two-dimensional material channel layer on the other side of the stacked gate structure; A first top contact electrode, located on the top surface of the drain region, and the first top contact electrode is electrically connected to the top surface of the drain region; A first bottom contact electrode, located on the bottom surface of the drain region, and the first bottom contact electrode is electrically connected to the bottom surface of the drain region; A second top contact electrode, located on the top surface of the source region, and the second top contact electrode is electrically connected to the top surface of the source region; A second bottom contact electrode, located on the bottom surface of the source region, and the second bottom contact electrode is electrically connected to the bottom surface of the source region.

2. The test structure according to claim 1, wherein, The test structure further comprises: a top gate contact electrode, located on the top surface of the top gate structure; A bottom gate contact electrode, located on the bottom surface of the bottom gate structure.

3. The test structure according to claim 1, wherein The test structure further comprises: an insulating layer, located between the substrate and the stacked gate structure, between the substrate and the first bottom contact electrode, and between the substrate and the second bottom contact electrode.

4. The test structure according to claim 1, wherein The first top contact electrode is used to apply a positive voltage, and the second top contact electrode is used to apply a zero potential.

5. The test structure according to claim 1, characterized in that, The material of the two-dimensional material channel layer comprises a transition metal chalcogenide.

6. The test structure according to claim 1, wherein The substrate comprises a dicing street region, and the test structure is located in the dicing street region.

7. A testing method, characterized in that, Comprising: Providing the test structure according to any one of claims 1 to 6; Applying corresponding test signals to the first top contact electrode and the second top contact electrode, for making the first top contact electrode, the first bottom contact electrode, the two-dimensional material channel layer, the second top contact electrode and the second bottom contact electrode form a test path; Obtaining the channel resistance value of the two-dimensional material channel layer of the test path; Obtaining the contact resistance value between the first top contact electrode and the drain region of the test path; Obtaining the contact resistance value between the second top contact electrode and the source region of the test path.

8. The test method according to claim 7, characterized in that, The step of applying corresponding test signals to the first top contact electrode and the second top contact electrode comprises: applying a positive voltage to the first top contact electrode, and applying a zero potential to the second top contact electrode.

9. The test method according to claim 7, characterized in that, The step of obtaining the channel resistance value of the two-dimensional material channel layer of the test path comprises: obtaining a first current value of the test path; after obtaining the first current value, measuring a first voltage value of the first bottom contact electrode; measuring a second voltage value of the second bottom contact electrode; obtaining the channel resistance value of the two-dimensional material channel layer through the first voltage value, the second voltage value and the first current value.

10. The test method according to claim 9, characterized in that, Obtain the channel resistance value R of the two-dimensional material channel layer ch =(V1 - V2) / I1, where V1 represents the first voltage value, V2 represents the second voltage value, and I1 represents the first current value.

11. The test method according to claim 7, wherein The steps of obtaining the contact resistance value between the first top surface contact electrode of the test path and the drain region include: obtaining the first current value of the test path; after obtaining the first current value, measuring the third voltage value of the first top surface contact electrode; measuring the fourth voltage value of the first bottom surface contact electrode; and obtaining the contact resistance value between the first top surface contact electrode and the drain region through the first current value, the third voltage value, and the fourth voltage value.

12. The test method according to claim 11, wherein Obtain the contact resistance value R between the first top surface contact electrode and the drain region c1 =(V3 - V4) / I1, where V3 represents the third voltage value, V4 represents the fourth voltage value, and I1 represents the first current value.

13. The testing method according to claim 7, wherein The steps of obtaining the contact resistance value between the second top surface contact electrode of the test path and the source region include: obtaining the first current value of the test path; after obtaining the first current value, measuring the fifth voltage value of the second top surface contact electrode; measuring the sixth voltage value of the second bottom surface contact electrode; and obtaining the contact resistance value between the second top surface contact electrode and the source region through the first current value, the fifth voltage value, and the sixth voltage value.

14. The test method according to claim 13, wherein Obtain the contact resistance value R between the second top surface contact electrode and the source region c2 =(V5 - V6) / I1, where V5 represents the fifth voltage value, V6 represents the sixth voltage value, and I1 represents the first current value.

15. The test method according to claim 7, wherein In the step of providing the test structure, the test structure further includes: a top gate contact electrode located on the top surface of the top gate structure; a bottom gate contact electrode located on the bottom surface of the bottom gate structure; In the step of applying corresponding test signals to the first top surface contact electrode and the second top surface contact electrode, voltage signals are also applied to the top gate contact electrode and the bottom gate contact electrode to make the two-dimensional material channel layer between the drain region and the source region in a conducting state.

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