Copper seed layer and preparation method and application thereof

Abstract

The invention provides a copper seed layer and a preparation method and application thereof, and relates to the technical field of semiconductor packaging, and according to the preparation method provided by the invention, deposition of a copper film is carried out by adopting a three-step method during deposition. The method comprises the following steps of: 1, depositing a high-hydrogen-content copper film layer on the surface of a glass substrate as a bottommost layer to reduce the damage to the surface of a sample and improve the compactness of the film; the second step is a normal copper film layer, and the deposition rate of the copper film is increased; and the third step is hydrogen glow modification for removing weak bonds on the surface of the thin film and amidino substances which are not completely reacted with the copper precursor, so that the compactness of the outer copper thin film is improved, and a good seed layer thin film is provided for subsequent copper electroplating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor packaging, in particular to a copper seed layer and a preparation method and application thereof. BACKGROUND

[0002] With the evolution of semiconductor manufacturing process to deep sub-micron and nanometer level, the traditional photolithography technology is gradually approaching the limit, the increase of the number of integrated circuit transistors and the reduction of the feature size are more and more slow and difficult, and the continuation of Moore's Law is facing great challenges. At the same time, the interconnection delay problem caused by too long signal transmission distance in traditional packaging technology has become increasingly prominent, and it has been difficult to meet the stringent requirements of modern chips for high-speed operation and low power consumption. In order to effectively cope with these bottleneck problems of integrated circuits and packaging technology, three-dimensional integration technology has emerged, providing a new technical path for the development of the industry.

[0003] As an innovative vertical electrical interconnection technology, the Through Glass Via (TGV) technology realizes high-density interconnection between chips and chips, and between chips and substrates by building vertical electrical connections on glass substrates. This technology not only expands the integration capability of chips in the vertical dimension, but also provides an ideal solution for high-performance chip packaging due to its shortest electrical transmission path and excellent anti-interference performance.

[0004] In the field of thin film deposition technology, Atomic Layer Deposition (ALD) has the advantages of dense structure, excellent conformality, and low defect density, especially suitable for depositing uniform and conformal thin films on 3D porous substrates with large aspect ratio and complex structure. Compared with traditional physical vapor deposition (PVD) sputtering and chemical vapor deposition (CVD) technology, ALD exhibits more prominent technical advantages.

[0005] Plasma Enhanced Atomic Layer Deposition (PE-ALD) is a special variant of Atomic Layer Deposition (ALD), which realizes thin film deposition at lower temperature by enhancing the reactivity of the precursor with plasma, and can more accurately control the properties of the thin film. However, the traditional PE-ALD copper plating process still has some shortcomings, such as poor adhesion when depositing on inorganic surfaces (such as glass). This may cause subsequent copper electroplating to fall off, as well as high resistance, etc.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] One of the purposes of the present application is to provide a copper seed layer to at least solve one of the technical problems existing in the prior art. The present application uses a PE-ALD process to deposit a copper seed layer, and uses a high-hydrogen-content copper thin film layer as the bottommost layer to reduce damage to the sample surface and improve the denseness of the thin film.

[0008] The second purpose of the present application is to provide a preparation method of a copper seed layer.

[0009] The third purpose of the present application is to provide an application of a copper seed layer or a preparation method of a copper seed layer in the preparation of a semiconductor product.

[0010] In order to achieve the above-mentioned purposes of the present application, the following technical solutions are adopted: In a first aspect, the present application provides a copper seed layer, comprising: a first copper layer and a second copper layer which are sequentially stacked on a glass substrate. The first copper layer comprises a plurality of first cyclic deposition layers, and the second copper layer comprises a plurality of second cyclic deposition layers, wherein the hydrogen content of the first cyclic deposition layers is greater than the hydrogen content of the second cyclic deposition layers.

[0011] Further, a transition layer is further included between the glass substrate and the first copper layer. The transition layer comprises at least one of a Ti layer, a TiN layer, a Ta layer, and a TaN layer.

[0012] In a second aspect, the present application provides a preparation method of a copper seed layer, comprising the following steps: sequentially stacking and preparing a first copper layer and a second copper layer on a glass substrate to obtain a copper seed layer.

[0013] Further, the thickness of the copper seed layer is 25-40 nm. Preferably, the first copper layer and the second copper layer are prepared by a plasma-enhanced atomic layer deposition method.

[0014] Further, the preparation process of the first copper layer comprises: alternately introducing a precursor and a reactant to deposit the first copper layer on the glass substrate. Preferably, one cycle of introducing the precursor and the reactant is defined as one first cyclic deposition, and the preparation process of the first copper layer comprises a plurality of first cyclic depositions. Preferably, the number of cycles of the first cyclic deposition is 10-30 times. Preferably, when depositing the first copper layer, the flow rate of the reactant is 200-2000 sccm. Preferably, when depositing the first copper layer, the precursor is introduced into the reaction chamber through a carrier gas, and the flow rate of the carrier gas is 200-2000 sccm. Preferably, the time for feeding the reactant is 2-7 times the time for feeding the precursor, and the flow rate of the reactant is 2-5 times the flow rate of the carrier gas.

[0015] Further, the preparation process of the second copper layer comprises: alternately feeding the precursor and the reactant to deposit the second copper layer on the first copper layer. Preferably, the preparation process of the second copper layer comprises a plurality of second cycle depositions, each second cycle deposition comprising feeding the precursor and the reactant once. Preferably, the flow rate of the reactant is 100-1500 sccm when depositing the second copper layer. Preferably, the flow rate of the carrier gas is 200-1000 sccm when feeding the precursor into the reaction chamber by the carrier gas when depositing the second copper layer.

[0016] Further, the precursor used for preparing the first copper layer and the second copper layer comprises bis(N,N-di-sec-butylacetamidine)dicopper, and the reactant used for preparing the first copper layer and the second copper layer comprises hydrogen plasma.

[0017] Further, the glass substrate is preheated before preparing the first copper layer. Preferably, the temperature of the preheated glass substrate is 90-200℃.

[0018] Further, a modification treatment is performed after preparing the second copper layer. Preferably, the modification treatment is hydrogen glow modification. Preferably, the modification treatment is performed for 3-8 seconds, the radio frequency power is 100-300 W, and the flow rate of hydrogen is 200-2000 sccm.

[0019] In a third aspect, the application provides an application of the copper seed layer or the preparation method of the copper seed layer in preparing a semiconductor product.

[0020] Compared with the prior art, the application has the following beneficial effects: The copper seed layer provided by the application can reduce the damage to the sample surface, improve the compactness of the thin film, and then deposit a normal copper thin film layer (i.e., the second copper layer) to accelerate the deposition rate of the copper thin film.

[0021] The preparation process of the copper seed layer provided by the application can increase the adhesion of the copper thin film in the glass via hole (and / or the surface of the glass substrate) and the compactness of the thin film, so as to meet the requirements of the glass via hole (TGV) or other glass substrates for high-adhesion and high-compactness copper thin films. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The flow chart of the three-step process of the plasma-enhanced atomic layer deposition of copper film in the present application; Figure 2 The chemical structural formula of [Cu(sBu-amd)]2 in the present application; Figure 3 The reaction equation of [Cu(sBu-amd)]2 and H plasm in the present application; Figure 4 The complete process flow chart of the plasma-enhanced atomic layer deposition of copper film in the present application; Figure 5 The electron microscope photograph of the product after the electroplating process of filling the TGV via hole after depositing a 30nm copper film on the surface of the glass substrate plated with TiN in Example 1; Figure 6 The electron microscope photograph of the product after the electroplating process of filling the TGV via hole after depositing a copper film on the surface of the glass substrate plated with TiN in Example 2; Figure 7 The electron microscope photograph of the product after the electroplating process of filling the TGV via hole after depositing a copper film on the surface of the glass substrate plated with TiN in Example 3; Figure 8 The top view of the product after the electroplating process of filling the TGV via hole after depositing a copper film on the surface of the glass substrate plated with TiN in Example 6; Figure 9 The electron microscope photograph of the product after the electroplating process of filling the TGV via hole after depositing a copper film on the surface of the glass substrate plated with TiN in Comparative Example 1; Figure 10 The electron microscope photograph of the product after the electroplating process of filling the TGV via hole after depositing a copper film on the surface of the glass substrate plated with TiN in Comparative Example 2. DETAILED DESCRIPTION

[0024] Unless otherwise defined, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any latent ambiguity, definitions provided herein take precedent over any dictionary or extrinsic definition. In this application, the use of "or" means "and / or" unless stated otherwise. Furthermore, use of the term "including" as well as other forms such as "include", "includes" for indicating combinations of elements is not limiting.

[0025] The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the present application.

[0026] The first aspect of the present application provides a copper seed layer, comprising: a first copper layer and a second copper layer which are sequentially stacked on a glass substrate. The first copper layer comprises a plurality of first cyclic deposition layers, and the second copper layer comprises a plurality of second cyclic deposition layers, wherein the hydrogen content of the first cyclic deposition layers is greater than the hydrogen content of the second cyclic deposition layers.

[0027] In the present application, a copper thin film layer with high hydrogen content (i.e. the first copper layer) is deposited as the bottom layer on the surface of the glass substrate to reduce damage to the sample surface and improve the denseness of the thin film, and then a normal copper thin film layer (i.e. the second copper layer) is prepared to accelerate the deposition rate of the copper thin film. In the conventional PEALD process, the atomic percentage of H element in the material is usually <5 at%, and the atomic percentage of H element in the first copper layer in the present application is greater than that in the second copper layer, which meets the requirements of high adhesion and high denseness of the copper thin film for glass through-via (TGV) or other glass substrates.

[0028] In some preferred embodiments, a transition layer is further included between the glass substrate and the first copper layer; the transition layer comprises at least one of a Ti layer, a TiN layer, a Ta layer and a TaN layer.

[0029] Specifically, in the TGV metallization process step, a transition layer such as Ti, TiN, Ta, TaN, etc. can be plated on the glass before copper plating, and the process of the present application is still applicable when the copper seed layer is deposited on the transition layer.

[0030] The second aspect of the present application provides a preparation method of a copper seed layer, comprising the following steps: sequentially stacking a first copper layer and a second copper layer on a glass substrate to obtain a copper seed layer.

[0031] In some preferred embodiments, the thickness of the copper seed layer is 25-40 nm, for example, it can be 25 nm, 30 nm, 35 nm, 40 nm, etc.

[0032] Preferably, the first copper layer and the second copper layer are prepared by using a plasma enhanced atomic layer deposition method.

[0033] In some preferred embodiments, the precursors used for preparing the first copper layer and the second copper layer include bis(N,N-di-sec-butylacetamidinate)dicopper, and the reactants used for preparing the first copper layer and the second copper layer include hydrogen plasma (H plasm) after ionization of hydrogen.

[0034] Specifically, in the present application, the precursors are transported by using nitrogen or argon as a carrier gas, and the precursors and the reactants are alternately introduced into the cavity for reaction. The temperature of the copper precursor source bottle is set to be 80-120℃, and the temperature of the heat tracing band of the gas circuit is also set to be 80-120℃ to prevent the precursors from condensing in the pipeline.

[0035] In some preferred embodiments, the preparation process of the first copper layer includes: alternately introducing the precursors and the reactants to deposit the first copper layer on the glass substrate; Preferably, one first cycle deposition is performed by introducing the precursors and the reactants once, and the first cycle deposition layer is deposited after one first cycle deposition. The preparation process of the first copper layer includes a plurality of first cycle depositions. Preferably, the number of cycles of the first cycle deposition is 10-30 times, for example, it can be 10 times, 20 times, 30 times, etc.

[0036] Preferably, when depositing the first copper layer, the flow rate of the reactants is 200-2000 sccm; further preferably, it is 500-1000 sccm, for example, it can be 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, 1000 sccm, etc. Preferably, when depositing the first copper layer, the precursors are introduced into the reaction cavity by using a carrier gas, and the flow rate of the carrier gas is 200-2000 sccm; further preferably, it is 100-300 sccm, for example, it can be 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, etc.

[0037] Preferably, when depositing the first copper layer, the introduction time of the reactants is 2-7 times the introduction time of the precursors, and the flow rate of the reactants is 2-5 times the flow rate of the carrier gas.

[0038] For example, the "2-7 times" can be 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, etc. For example, the "2-5 times" can be 2 times, 3 times, 4 times, 5 times, etc.

[0039] Specifically, when depositing the first copper layer, the present application reduces the opening time of the copper source ALD valve, increases the hydrogen flow, and reduces the radio frequency power, thereby reducing the deposition rate and etching the weak bonds in the deposited copper film with hydrogen plasma to improve the compactness of the film.

[0040] In some preferred embodiments, the preparation of the second copper layer comprises: alternately introducing the precursor and the reactant to deposit the second copper layer on the first copper layer; Preferably, one second cycle deposition is performed by introducing the precursor and the reactant once, and the preparation of the second copper layer comprises several second cycle depositions; Preferably, when depositing the second copper layer, the flow rate of the reactant is 100-1500 sccm; further preferably, 400-600 sccm, for example, 400 sccm, 500 sccm, 600 sccm, etc. Preferably, when depositing the second copper layer, the precursor is introduced into the reaction chamber through the carrier gas, and the flow rate of the carrier gas is 200-1000 sccm; further preferably, 200-500 sccm, for example, 200 sccm, 300 sccm, 400 sccm, 500 sccm, etc.

[0041] Specifically, when preparing the first copper layer, the flow rate and the introduction time of hydrogen are adjusted back to normal after 10-30 cycles, and the next step of normal copper film deposition (i.e., preparation of the second copper layer) is performed to speed up the process cycle. When depositing the second copper layer, the opening time of the copper source ALD valve and the flow rate of hydrogen are adjusted back to the normal value for normal copper film deposition to restore the normal deposition rate.

[0042] In some preferred embodiments, the glass substrate is preheated before the first copper layer is prepared; Preferably, the temperature of the glass substrate after preheating is 90-200℃, for example, 90℃, 100℃, 150℃, 180℃, 200℃, etc.

[0043] Specifically, in the preheating process, the temperature of the heating plate is set to 100-250℃, thereby controlling the temperature of the glass substrate to 90-200℃. The copper film deposited below 300℃ has almost no impurities, but considering that the agglomeration phenomenon will be more serious at a higher temperature, the temperature is required to be controlled within the range of 90-200℃. After the substrate is placed inside the cavity, the substrate is heated to the set temperature by the bottom heating plate, and then needs to be kept at constant temperature for 5-10 minutes.

[0044] Preferably, the pressure range is 100-600 Pa when depositing the first copper layer and the second copper layer, for example, it can be 100 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, etc.

[0045] In some preferred embodiments, after preparing the second copper layer, a modification treatment is performed; Preferably, the modification treatment adopts hydrogen glow modification.

[0046] Specifically, only H plasma is introduced in the hydrogen glow modification process without introducing copper source, so that no copper film is deposited in this step and only the outer copper film is modified. The hydrogen glow modification can break the weak bonds in the outermost film, improve the compactness of the outer film, and remove the imidazole groups of the copper precursor which are not completely reacted. The quality of the copper film is improved, and the content of C and O elements in the film is reduced.

[0047] The present application adopts a three-step method (including the first step of depositing a high-hydrogen-content copper film layer as the bottom layer on the surface of the glass substrate, the second step of normal copper film layer, and the third step of hydrogen glow modification) for plasma-enhanced atomic deposition of copper film, which can increase the adhesion of the copper film in the glass via or on the surface of the glass substrate and the compactness of the film, so as to meet the requirements of high adhesion and high compactness of the copper film for glass via (TGV) or other glass substrates.

[0048] Preferably, the time of the modification treatment is 3-8 s, for example, it can be 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, etc.; the radio frequency power is 100-300 W, for example, it can be 100 W, 200 W, 300 W, etc.; and the hydrogen flow rate is 200-2000 sccm.

[0049] Specifically, in the hydrogen glow modification process, the frequency is controlled to be between 100-300 W. Too small frequency may result in a long time for this process step, and too large frequency may result in damage to the normal copper film on the inner side of the surface.

[0050] In the optional solution of the present application, as shown in the figure, the preparation process of the copper seed layer includes the following steps: Figures 1-4 S1, placing the glass substrate on the heating plate for preheating; S2, depositing a high-hydrogen-content bottom copper film; S3, introducing copper precursor and H plasm to deposit copper film, stopping the introduction of copper source when the target film thickness is reached, and performing the last step of hydrogen glow modification; S4, performing hydrogen glow modification.

[0051] ​The application provides a preparation method of a copper seed layer, which is an atomic layer deposition copper process for TGV and other glass substrates, and copper seed layers are deposited in glass substrate through holes (or surfaces) by PE-ALD. The process adopts a three-step method to deposit copper films. The method comprises the following steps: in the first step, a high-hydrogen-content copper film layer is deposited on the surface of the glass substrate as the bottommost layer, so as to reduce damage to the sample surface and improve the compactness of the film; in the second step, a normal copper film layer is deposited, so as to accelerate the deposition rate of the copper film; and in the third step, hydrogen glow modification is performed, so as to remove weak bonds on the surface of the film and imidazolyl groups of the copper precursor which are not completely reacted, and improve the compactness of the outer copper film, thereby providing a good seed layer film for subsequent copper electroplating. The process can effectively meet the strict requirements of the compactness and adhesion of the seed layer for subsequent copper electroplating of glass through holes (TGV).

[0052] The process can meet the film plating requirements of substrates with a large aspect ratio, and the aspect ratio can be about 35:1.

[0053] The third aspect of the application provides an application of a copper seed layer or a preparation method of the copper seed layer in the preparation of semiconductor products. The preparation method is an atomic layer deposition copper seed layer process for glass through holes (TGV) channels in semiconductor packaging technology. The process can meet the film plating requirements of substrates with a large aspect ratio, and the aspect ratio can be about 35:1.

[0054] The application will be further described through examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0055] The aspect ratios of the substrates in the following examples and comparative examples are all 20:1.

[0056] Example 1 This example provides a copper seed layer, and the preparation process is as follows: (1) Open the device cavity cover, place the glass substrate plated with TiN into the cavity, set the temperature of the bottom heating plate to 130℃, and preheat the substrate. When the temperature of the substrate reaches 110℃, the preheating of the substrate is completed. H plasma is introduced for 90s to clean the substrate and remove impurities such as oxides and nitrides on the surface.

[0057] (2) Alternately introduce [Cu(sBu-amd)]2 and H plasm into the cavity to deposit a Cu seed layer, wherein the carrier gas of [Cu(sBu-amd)]2 is N2; The carrier gas flow is set to 300 sccm, and the hydrogen flow is set to 600 sccm. The Cu metal source ALD valve opening time is set to 1 s, and the carrier gas purge duration is set to 10 s (the carrier gas continuous purge can remove the inside of the cavity, the excess precursor, and prevent CVD reaction from occurring). The H plasma inlet time is set to 3 s, and the purge time is set to 10 s. After the process starts, the Cu metal source ALD valve is opened first, the copper source is introduced into the cavity and the excess precursor is purged. Then the H plasma is introduced, the power supply power is set to 500 W, the reducing agent is introduced into the cavity to react with the copper source to generate copper single element, and the excess gas is purged.

[0058] (3) After 40 cycles, the deposition of the bottom layer of copper film with high hydrogen content (i.e., the first copper layer) is completed; Then the carrier gas flow is set to 500 sccm, and the hydrogen flow is set to 500 sccm. The Cu metal source ALD valve opening time is set to 1 s, and the carrier gas purge duration is set to 10 s. The H plasma inlet time is set to 1 s, and the purge time is set to 10 s.

[0059] One cycle is counted as one complete copper source introduction and H plasm introduction. After 280 cycles, the deposition of the normal copper film layer (i.e., the second copper layer) is completed, and the total thickness of the copper film (i.e., the first copper layer and the second copper layer) is 30 nm.

[0060] (4) After the film plating step is completed, the power supply power is set to 200 W for hydrogen glow modification, and the hydrogen flow is set to 300 sccm. After 2 s of H plasm introduction, one cycle of N2 purge is performed. After 5 cycles, the hydrogen glow modification process is completed, and the cavity enters the out-purge stage.

[0061] (5) The upper limit value of the cleaning vacuum degree is set to 5000 Pa, and the lower limit value is set to 50 Pa. The flow meter is set to 2000 sccm, and the cycle number is set to 15. The cavity angle valve is opened, the cavity vacuum degree is extracted to the lower limit value of the cleaning vacuum degree, the cavity angle valve is closed, the pneumatic valve is opened after 1 s, and the nitrogen gas is injected into the cavity at the flow rate set by the flow meter. The cavity pressure reaches the upper limit value of the cleaning vacuum degree, the pneumatic valve is closed after 1 s, and the gas extraction operation is performed in the previous operation mode. After 15 cycles of purging, the process is completed, and the substrate can be taken out.

[0062] Example 2 The embodiment provides a copper seed layer, which is different from the embodiment 1. In step (2), when the first copper layer is prepared, the carrier gas flow is set to 200 sccm, the hydrogen flow is set to 1000 sccm, the Cu metal source ALD valve opening time is set to 1 s, and the H plasma inlet time is set to 2 s. In step (3), when preparing the second copper layer, the carrier gas flow rate is set to 300 sccm, the hydrogen flow rate is set to 600 sccm, the Cu metal source ALD valve opening time is set to 0.5 s, and the H plasma input time is set to 1 s; The total thickness of the copper film is 25 nm.

[0063] In step (4), the power supply power is set to 100 W for hydrogen glow modification, the hydrogen flow rate is set to 300 sccm, and the Hplasm input time is 2 s.

[0064] The remaining steps are consistent with Example 1.

[0065] Example 3 This example provides a copper seed layer, which is different from Example 1 in that: In step (2), when preparing the first copper layer, the carrier gas flow rate is set to 100 sccm, the hydrogen flow rate is set to 500 sccm, the Cu metal source ALD valve opening time is set to 1 s, and the H plasma input time is set to 7 s; In step (3), when preparing the second copper layer, the carrier gas flow rate is set to 200 sccm, the hydrogen flow rate is set to 400 sccm, the Cu metal source ALD valve opening time is set to 0.3 s, and the H plasma input time is set to 3 s; The total thickness of the copper film is 35 nm.

[0066] In step (4), the power supply power is set to 300 W for hydrogen glow modification, the hydrogen flow rate is set to 300 sccm, and the Hplasm input time is 2 s.

[0067] The remaining steps are consistent with Example 1.

[0068] Example 4 This example provides a copper seed layer, which is different from Example 1 in that: In step (2), when preparing the first copper layer, the carrier gas flow rate is set to 300 sccm, the hydrogen flow rate is set to 1200 sccm, the Cu metal source ALD valve opening time is set to 1 s, and the H plasma input time is set to 1.5 s; In step (3), when preparing the second copper layer, the carrier gas flow rate is set to 600 sccm, the hydrogen flow rate is set to 400 sccm, the Cu metal source ALD valve opening time is set to 0.5 s, and the H plasma input time is set to 2 s; The total thickness of the copper film is 20 nm.

[0069] In step (4), the power supply power is set to 90 W for hydrogen glow modification, the hydrogen flow rate is set to 300 sccm, and the Hplasm input time is 2 s.

[0070] The remaining steps are consistent with Example 1.

[0071] Example 5 This example provides a copper seed layer, which is different from Example 1 in that: In step (2), when preparing the first copper layer, the carrier gas flow rate is set to 100 sccm, the hydrogen flow rate is set to 100 sccm, the Cu metal source ALD valve opening time is set to 1 s, and the H plasma input time is set to 8 s; In step (3), when preparing the second copper layer, the carrier gas flow rate is set to 100 sccm, the hydrogen flow rate is set to 50 sccm, the Cu metal source ALD valve opening time is set to 0.5 s, and the H plasma input time is set to 3 s; The total thickness of the copper film is 25 nm.

[0072] In step (4), the power supply power is set to 310 W for hydrogen glow modification, the hydrogen flow rate is set to 300 sccm, and the Hplasm input time is 2 s.

[0073] The remaining steps are consistent with Example 1.

[0074] Example 6 This example provides a copper seed layer, which is different from Example 1 in that: step (4) is not performed, i.e., hydrogen glow modification is not performed, and the remaining steps are consistent with Example 1.

[0075] Comparative Example 1 This comparative example provides a copper seed layer, which is different from Example 1 in that: In step (2), when preparing the first copper layer, the carrier gas flow rate is set to 200 sccm, the hydrogen flow rate is set to 400 sccm, the Cu metal source ALD valve opening time is set to 1 s, and the H plasma input time is set to 2 s; In step (3), when preparing the second copper layer, the carrier gas flow rate is set to 200 sccm, the hydrogen flow rate is set to 600 sccm, the Cu metal source ALD valve opening time is set to 1 s, and the H plasma input time is set to 3 s; The remaining steps are consistent with Example 1.

[0076] Comparative Example 2 This comparative example provides a copper seed layer, which is different from Example 1 in that: step (2) is not performed, i.e., the preparation of the first copper layer is not performed, and the remaining steps are consistent with Example 1.

[0077] Test samples: The copper seed layers prepared by Examples 1-6 and Comparative Examples 1-2 are used as samples for testing.

[0078] Adhesion test method: tape is pasted to the glass surface, and then the tape is torn to check the copper shedding.

[0079] The test results are shown in Table 1.

[0080] Table 1

[0081] From the data in Table 1, it can be seen that, through Examples 1 and 4-5, under the specific preparation process parameters of the application, the copper seed layer prepared has stronger adhesion. Through Examples 1 and 6, it can be seen that the hydrogen glow modification step can enhance the adhesion of the copper seed layer. Through Examples 1 and Comparative Examples 1 and 2, it can be seen that only by first preparing a high-hydrogen-content copper thin film layer as the bottom layer, and then preparing a normal copper thin film layer, can the adhesion and density of the copper seed layer be improved. Figure 9 Figure 9 In Comparative Example 2, the first copper layer is not prepared, and the copper seed layer has many pores in the middle of the plating layer. Due to the poor density of the previous section, the subsequent electroplating adsorption is not uniform, and the adhesion and density of the copper seed layer of Comparative Example 2 are not as good as those of Example 1. Figure 10 Figure 10 In Comparative Example 2, the first copper layer is not prepared, and the copper seed layer has many pores in the middle of the plating layer. Due to the poor density of the previous section, the subsequent electroplating adsorption is not uniform, and the adhesion and density of the copper seed layer of Comparative Example 2 are not as good as those of Example 1.

[0082] Through Examples 1-3, Figures 5-7 It can be seen that the copper seed layers prepared in Examples 1-3 have strong density, especially in Example 1, Figure 5 In Example 1, there are basically no pores after electroplating, Figures 6-7 (Examples 2-3, respectively), only a small part of the internal area has pores. Through Examples 1-3, Figure 8 It can be seen that, in Example 6, which does not undergo the hydrogen modification ALD copper plating process, after electroplating copper, the glass surface and the through hole, after being adhered by the tape, have many copper shedding phenomena. This is due to the fact that the copper seed layer plated by ALD is not dense enough, which causes the electroplated copper to not grow well along the seed layer during the subsequent electroplating process.

[0083] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.​​

Claims

1. A copper seed layer, characterized in that: include: A first copper layer and a second copper layer are sequentially stacked on a glass substrate; The first copper layer includes a plurality of first cyclic deposition layers, and the second copper layer includes a plurality of second cyclic deposition layers. The hydrogen content of the first cyclic deposition layers is greater than that of the second cyclic deposition layers.

2. The copper seed layer according to claim 1, characterized in that A transition layer is further included between the glass substrate and the first copper layer; The transition layer includes at least one of a Ti layer, a TiN layer, a Ta layer and a TaN layer.

3. The method for preparing a copper seed layer according to claim 1 or 2, wherein: The method comprises the following steps: sequentially stacking a first copper layer and a second copper layer on a glass substrate to obtain a copper seed layer.

4. The preparation method according to claim 3, wherein The thickness of the copper seed layer is 25-40 nm; Preferably, the first copper layer and the second copper layer are prepared by plasma enhanced atomic layer deposition.

5. The preparation method according to claim 3, characterized in that The preparation process of the first copper layer includes: alternately introducing a precursor and a reactant to deposit the first copper layer on a glass substrate; Preferably, introducing the precursor and reactant once is regarded as a first cycle deposition, and a first cycle deposition layer is obtained through one first cycle deposition, and the preparation process of the first copper layer includes several first cycle depositions; Preferably, the number of cycles of the first cycle deposition is 10-30 times; Preferably, when depositing the first copper layer, the flow rate of the reactants is 200-2000 sccm; Preferably, when depositing the first copper layer, the precursor is introduced into the reaction chamber by a carrier gas, and the flow rate of the carrier gas is 200-2000 sccm; Preferably, when depositing the first copper layer, the introduction time of the reactant is 2-7 times that of the precursor, and the flow rate of the reactant is 2-5 times that of the carrier gas.

6. The preparation method according to claim 3, characterized in that The preparation process of the second copper layer includes: alternately introducing a precursor and a reactant to deposit the second copper layer on the first copper layer; Preferably, the introduction of the precursor and the reactant once is regarded as one second cycle deposition, and a second cycle deposition layer is obtained through one second cycle deposition. The preparation process of the second copper layer includes several second cycle depositions. Preferably, when depositing the second copper layer, the flow rate of the reactants is 100-1500 sccm; Preferably, when depositing the second copper layer, the precursor is introduced into the reaction chamber via a carrier gas, and the flow rate of the carrier gas is 200-1000 sccm.

7. The preparation method according to claim 3, characterized in that The precursor used to prepare the first copper layer and the second copper layer includes bis(N,N-di-sec-butylacetamidine)dicopper, and the reactant used to prepare the first copper layer and the second copper layer includes hydrogen plasma.

8. The preparation method according to claim 3, characterized in that Before forming the first copper layer, the glass substrate is preheated; Preferably, the temperature of the glass substrate after preheat treatment is 90-200°C.

9. The preparation method according to claim 3, characterized in that After preparing the second copper layer, a finishing treatment is performed; Preferably, the modification process adopts hydrogen glow modification; Preferably, the modification treatment time is 3-8 seconds, the radio frequency power is 100-300W, and the hydrogen flow rate is 200-2000sccm.

10. Use of the copper seed layer according to claim 1 or 2 or the method for preparing the copper seed layer according to claims 3 to 9 in preparing semiconductor products.

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