A method for analyzing the total dose effect on the performance changes of TSV structural materials

Abstract

The present invention discloses a method for analyzing the total dose effect on the performance change of TSV structural materials. First, a three-dimensional interconnected TSV adapter is manufactured, and the scattering parameters of the adapter under different total dose irradiation are tested by a vector network analyzer; secondly, the scattering parameters of the adapter under different irradiation doses are fitted by HFSS software, and the dielectric constants of materials Si and SiO2 in the TSV structure under different irradiation doses are extracted; then the relationship between the irradiation dose and the dielectric constants of materials Si and SiO2 in the TSV structure is summarized; finally, the material parameters of the TSV structure under any irradiation dose are analyzed based on the obtained relationship. Compared with the prior art, the present invention can quickly, conveniently, accurately and economically analyze the physical parameters of TSV structural materials under any irradiation dose by combining finite element simulation software to construct the relationship between the irradiation dose and the dielectric constants of TSV structural materials Si and SiO2.

Description

Technical Field

[0001] The invention relates to a method for analyzing the total dose effect on the performance change of TSV structural materials. Background Art

[0002] Miniaturization of aerospace devices is the current development trend. Three-dimensional integrated packaging based on technologies such as TSV (through silicon via), RDL (Redistribution Layer) and Bump is gradually developing towards miniaturization, light weight, high density and high reliability, providing a new way to reduce the size of devices. TSV technology refers to the processing of micro-through holes on silicon wafers, filling conductive materials inside the silicon wafers, and realizing vertical interconnection between chips through TSV technology. It is a key technology for three-dimensional packaging. However, three-dimensional microsystems used in space environments for a long time will be affected by the radiation effect, causing the oxide layer of the TSV structure to produce electron-hole pairs, resulting in changes in material properties, among which the main change is the dielectric constant of the oxide layer material, which in turn affects the signal transmission quality of the TSV structure and the entire microsystem. The scattering parameters can describe the frequency domain characteristics of the transmission channel. By measuring the scattering parameters of the TSV structure, the characteristics and quality of the signal transmission of the TSV structure can be obtained. However, the total dose effect irradiation test has problems such as high irradiation cost, limited particle accelerator resources, irreversibility of the experiment, and cumbersome measurement of physical parameters of TSV structural materials under a specified total dose irradiation dose. Summary of the invention

[0003] Purpose of the invention: In view of the above-mentioned prior art, a method for analyzing the total dose effect on the performance change of TSV structural materials is proposed, which can quickly, conveniently and economically analyze the physical parameters of TSV structural materials under any irradiation dose.

[0004] Technical solution: A method for analyzing the total dose effect on the performance change of TSV structural materials, including:

[0005] Step 1: Design and manufacture a batch of three-dimensional interconnect TSV adapters, and use a vector network analyzer to test the scattering parameters S21 of the three-dimensional interconnect TSV adapters before irradiation;

[0006] Step 2: According to the determined dose points, the three-dimensional interconnect TSV adapter is irradiated with a cobalt source, and then the vector network analyzer is used again to measure the scattering parameter S21 after irradiation at different doses;

[0007] Step 3: According to the three-dimensional interconnected TSV adapter board, a corresponding structural model is established in the HFSS software, and then the materials Si and SiO in the structural model are changed. 2The dielectric constant of the HFSS software is used to fit the scattering parameters simulated by the HFSS software with the measured scattering parameters;

[0008] Step 4: According to the scattering parameter S21 and the materials Si and SiO 2 The dielectric constant of the cobalt source is obtained, and the irradiation dose and the dielectric constant of the materials Si and SiO in the three-dimensional interconnect TSV adapter are obtained. 2 The functional relationship of the dielectric constant is:

[0009] y 1 =-1.43·e -x / 173.98 +13.33 (1)

[0010] y 2 =-0.81·e -x / 154.60 +4.71 (2)

[0011] Among them, y 1 is the dielectric constant of Si; y 2 is the dielectric constant of SiO2; x is the irradiation dose of the cobalt source;

[0012] Step 5: Predict the Si and SiO materials in the three-dimensional interconnect TSV transfer board at different dosage points based on the functional relationship 2 The dielectric constant value of .

[0013] Furthermore, the three-dimensional interconnect TSV adapter board includes: the bottom layer is the first EMC layer, and the Pi layer is covered on the first EMC layer; the Pi layer is the back RDL of the entire adapter board; the back RDL is the second EMC layer, the second EMC layer is wrapped with a silicon layer, a plurality of TSVs are opened on the silicon layer, and a silicon dioxide layer is provided on the inner surface of each TSV; the front RDL of the entire adapter board is above the second EMC layer, and a bump is provided between each TSV and the front RDL;

[0014] Among them, a first through-groove is opened on the back RDL, and a back signal RDL connecting two TSVs is embedded in the first through-groove, and the back signal RDL is insulated from the first through-groove by a first EMC tape; two second through-grooves are opened on the front RDL, the two second through-grooves are not connected to each other, and are respectively opposite to a TSV connected to the back signal RDL, and a front signal RDL is respectively arranged in the second through-grooves, and the front signal RDL is insulated from the second through-grooves by a second EMC tape.

[0015] Furthermore, in the three-dimensional interconnect TSV adapter board, the Pi layer thickness is 10um, the back RDL thickness is 7.5um, the silicon layer thickness is 200um, the TSV diameter is 35um, and the silicon dioxide layer thickness is 0.5um.

[0016] Beneficial effect: The total dose effect analysis method of the present invention on the performance change of TSV structure materials can calculate the Si, SiO and other materials of the three-dimensional interconnected TSV adapter under any dose irradiation. 2 The physical parameters of the three-dimensional TSV structure can greatly save time and omit the tedious steps of measuring the physical parameters of the three-dimensional TSV structure material under the specified irradiation dose, thereby greatly reducing the economic cost of analyzing the influence of the total dose effect on the electrical properties of the three-dimensional TSV structure material. Moreover, by combining the experiment with the HFSS finite element simulation software, the number of experiments is reduced while ensuring the accuracy of the results, thereby achieving the purpose of reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the method of the present invention;

[0018] Figure 2 It is a schematic diagram of the three-dimensional structure of a three-dimensional interconnected TSV adapter board;

[0019] Figure 3 Schematic diagram of the planar structure of a three-dimensional interconnected TSV adapter board, wherein (a) is a schematic diagram of the front wiring structure, (b) is a schematic diagram of the front wiring structure, and (c) is a schematic diagram of the cross-sectional structure;

[0020] Figure 4 This is a scene diagram of the scattering parameter test of the three-dimensional interconnect TSV adapter board;

[0021] Figure 5 The measured scattering parameter S21 of the 3D interconnect TSV adapter before irradiation;

[0022] Figure 6 is the scattering parameter S21 of the three-dimensional interconnect TSV adapter after irradiation at each dose point;

[0023] Figure 7 The measured and simulated scattering parameters S21 of the 3D interconnect TSV before irradiation;

[0024] Figure 8 is the measured and simulated scattering parameter S21 after irradiation at each dose point;

[0025] Fig. 9 is the relationship between the irradiation dose and the dielectric constant of materials Si and SiO2;

[0026] Fig.10 This is the relationship between the irradiation dose and the dielectric constant of materials Si and SiO2 after fitting. DETAILED DESCRIPTION

[0027] The present invention will be further explained below in conjunction with the accompanying drawings.

[0028] like Figure 1As shown, a method for analyzing the total dose effect on the performance change of TSV structure materials includes the following steps:

[0029] Step 1: Design the Figure 2 , Figure 3 The three-dimensional interconnect TSV interposer shown has an overall size of 2300um×1075um×700um. The bottom layer of the adapter board is a 550um thick first EMC (Epoxy Molding Compound) layer 10; a 10um thick Pi (Polyimide) layer 9 is covered above the first EMC layer 10; above the Pi layer 9 is the back RDL (Re-Distribution Layer) 12 of the entire adapter board, which has a thickness of 7.5um; above the back RDL 12 is the second EMC layer 8, and the second EMC layer 8 is wrapped with a 200um thick silicon layer 7, and a number of TSVs 4 with a radius of 35um are opened on the silicon layer 7, and the inner surface of each TSV 4 is provided with a 0.5um thick silicon dioxide layer 3 as an insulating layer with the silicon layer 7; above the second EMC layer 8 is the front RDL 1, and a Bump 2 is provided between each TSV 4 and the front RDL 1. Among them, a first through-groove is formed on the back RDL 12, and a back signal RDL 6 connecting two TSVs 4 is embedded in the first through-groove, and the back signal RDL 6 is insulated from the first through-groove by a first EMC tape 13; two second through-grooves are formed on the front RDL 1, and the second through-grooves are not connected to each other, and each of them faces a TSV 4 connected to the back signal RDL 6, and each of the second through-grooves has a front signal RDL 5, and the front signal RDL 5 is insulated from the second through-groove by a second EMC tape 11. The second EMC layer 8 facilitates the production of TSVs and also plays a role in supporting TSVs; a TSV 4 with a radius of 35um is used as a bridge to connect the back signal RDL 6 and the front signal RDL 5.

[0030] The three-dimensional interconnected TSV adapter board can combine multiple interconnection methods to realize the electrical connection between chips and chips, chips and substrates, and can also realize signal connection in the vertical and horizontal directions. The TSV adapter board can integrate microelectronic chips of different materials, different process flows and different categories to realize the function of heterogeneous heterogeneous three-dimensional integration. In order to study and analyze the influence of the total dose effect on the performance of TSV structural materials, the present invention designs a batch of TSVs of three-dimensional interconnected TSV adapter boards, so that the influence of the total dose effect on it can be more clearly seen. At the same time, the adapter board is also designed with Bumps and RDL, which are interconnected with TSV, so that the influence of the radiation effect faced by the adapter board working in the space environment can be more realistically reflected.

[0031] In order to analyze the signal transmission capability of the adapter board, the GSG type feeding method is adopted. Therefore, the functions of TSV and RDL of the entire microsystem are divided into two types, namely communication and grounding. In order to prevent the signal RDL and the ground RDL from short-circuiting, the signal RDL and the ground RDL on the same plane are isolated by EMC. Then the electrical signal transmission performance of the TSV adapter board is measured, such as Figure 4 , select the probes that match the detection station and the three-dimensional interconnect TSV adapter board, preheat and calibrate the vector network analyzer to complete the pre-test preparation, and use the vector network analyzer to measure the scattering parameter S21 of the three-dimensional interconnect TSV adapter board, such as Figure 5 shown.

[0032] Step 2: Determine several dose points and irradiate the prepared TSV adapter board with a cobalt source. After the irradiation is completed, repeat the above steps and use a vector network analyzer to measure the scattering parameters S21 of the TSV adapter board at different dose points. Figure 6 shown.

[0033] Step 3: According to the designed three-dimensional interconnect TSV adapter, build the corresponding structural model in HFSS software, and then define the material properties, boundary conditions and excitation conditions to simulate the unirradiated S21 of the TSV adapter, such as Figure 7 Finally, the materials Si, SiO of the 3D interconnect TSV adapter are continuously changed in HFSS. 2 The dielectric constant of the simulated S21 curve is approximated to the measured S21 curve, as shown in Figure 8 As shown.

[0034] Step 4: Approximate the S21 curves simulated at each cobalt source irradiation dose point in the above steps in HFSS with the measured S21 to obtain the material Si and SiO at different irradiation doses. 2 The dielectric constant values ​​are sorted as follows: Fig. 9 As shown, a good functional relationship is then established with the dose, such as Fig.10 As shown in the following formula, it is found that the total dose effect mainly increases the dielectric constant of materials Si and SiO2 in the TSV structure, and the dose is exponentially related to the dielectric constant of materials Si and SiO2.

[0035] y 1 =-1.43·e -x / 173.98 +13.33#(1 )

[0036] y 2 =-0.81·e -x / 154.60 +4.71#(2 )

[0037] Among them, y 1is the dielectric constant of Si; y 2 is the dielectric constant of SiO2; x is the irradiation dose.

[0038] Step 5: Based on the functional relationship between the dielectric constants of Si and SiO2 materials in the TSV adapter board and the dose in the above steps, the dielectric constants of Si and SiO2 under any total dose irradiation can be calculated, and then the influence of the total dose effect on the electrical properties of the TSV structure material can be analyzed.

[0039] This embodiment uses the dielectric constants of Si and SiO2 simulated at a dose point of 540k for verification. The dielectric constants of Si and SiO2 at a dose of 540k are simulated and calculated in HFSS software as 13.2658 and 4.6853, while the dielectric constants of Si and SiO2 at a dose of 540k are calculated using formulas 1 and 2 as 13.26 and 4.69. It is found that the errors between the two are small, proving that the method has certain reliability. The present invention can provide an analysis method for analyzing the influence of the total dose effect on the electrical properties of materials in the TSV structure by establishing a functional relationship between the dielectric constants of Si and SiO2 materials in the TSV adapter plate and the dose, which will provide a methodological basis for the study of the electrical properties of device materials in a radiation environment.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for analyzing the total dose effect on the performance change of TSV structure materials, characterized in that: include: Step 1: Design and manufacture a batch of three-dimensional interconnect TSV adapters, and use a vector network analyzer to test the scattering parameters S21 of the three-dimensional interconnect TSV adapters before irradiation; Step 2: According to the determined dose points, the three-dimensional interconnect TSV adapter is irradiated with a cobalt source, and then the vector network analyzer is used again to measure the scattering parameter S21 after irradiation at different doses; Step 3: According to the three-dimensional interconnected TSV adapter board, a corresponding structural model is established in the HFSS software, and then the dielectric constants of the materials Si and SiO2 in the structural model are changed, and the scattering parameters simulated by the HFSS software are fitted with the measured scattering parameters; Step 4: According to the scattering parameter S21 and the dielectric constants of the materials Si and SiO2, the functional relationship between the cobalt source irradiation dose and the dielectric constants of the materials Si and SiO2 in the three-dimensional interconnect TSV adapter plate is obtained as follows: y1=-1.43·e -x / 173.98 +13.33 (1) y2=-0.81·e -x / 154.60 +4.71 (2) Wherein, y1 is the dielectric constant of Si; y2 is the dielectric constant of SiO2; x is the irradiation dose of the cobalt source; Step 5: predicting the dielectric constant values ​​of materials Si and SiO2 in the three-dimensional interconnect TSV adapter at different dosage points according to the functional relationship; The three-dimensional interconnect TSV adapter board comprises: the bottom layer is a first EMC layer (10), and a Pi layer (9) covers the first EMC layer (10); the Pi layer (9) is the back RDL (12) of the entire adapter board; the back RDL (12) is the second EMC layer (8), the second EMC layer (8) is wrapped with a silicon layer (7), a plurality of TSVs (4) are opened on the silicon layer (7), and a silicon dioxide layer (3) is provided on the inner surface of each TSV (4); the front RDL (1) of the entire adapter board is above the second EMC layer (8), and a bump (2) is provided between each TSV (4) and the front RDL (1); A first through-groove is formed on the back RDL (12), a back signal RDL (6) connected to two TSVs (4) is embedded in the first through-groove, and the back signal RDL (6) is insulated from the first through-groove by a first EMC tape (13); two second through-grooves are formed on the front RDL (1), the two second through-grooves are not connected to each other, and are respectively opposite to a TSV (4) connected to the back signal RDL (6), a front signal RDL (5) is respectively arranged in the second through-groove, and the front signal RDL (5) is insulated from the second through-groove by a second EMC tape (11).

2. The method for analyzing the total dose effect on the performance change of TSV structural materials according to claim 1, characterized in that: In the three-dimensional interconnect TSV adapter board, the thickness of the Pi layer (9) is 10um, the thickness of the back RDL (12) is 7.5um, the thickness of the silicon layer (7) is 200um, the diameter of the TSV (4) is 35um, and the thickness of the silicon dioxide layer (3) is 0.5um.

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