Ru thin film deposition process

Abstract

The invention discloses a Ru thin film deposition process, and relates to the technical field of semiconductors. In the Ru thin film deposition process, the metal organic compound precursor material is deposited on the surface of the silicon-based substrate to form the metal organic compound layer, and the metal organic compound precursor material and the silicon-based substrate are easily subjected to physical adsorption, so that the binding force between the metal organic compound precursor material and the silicon-based substrate is relatively good. Meanwhile, organic groups in the metal organic compound layer are also easily combined with a Ru precursor used for subsequently manufacturing the Ru thin film, so that the metal organic compound layer plays a role of an intermediate layer, the adsorption density of the Ru precursor on the substrate is increased, and the nucleation density can be improved. And the nucleation efficiency is improved under relatively high nucleation density, so that the total cycle number of the Ru film deposited by the atomic layer deposition process can be reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a Ru thin film deposition process. Background Art

[0002] Ru (ruthenium) is a rare precious metal belonging to the platinum group. Due to its excellent physical and chemical properties, Ru films are widely used in many high-tech fields, especially in microelectronics, magnetic storage, catalysts and sensors. At present, when Ru films are deposited on silicon substrates using atomic layer deposition, there is a long nucleation cycle, which leads to low process efficiency. Summary of the invention

[0003] The present application provides a Ru thin film deposition process, which can improve the deposition efficiency of the Ru thin film.

[0004] The embodiment of the present application is implemented as follows: The present application provides a Ru thin film deposition process, comprising: Depositing a metal organic compound layer on the surface of a silicon-based substrate using a metal organic compound precursor material; Purging the silicon-based substrate with an inert gas; A Ru thin film is deposited on the metal organic compound layer by an atomic layer deposition process.

[0005] In an optional embodiment, the step of depositing a metal organic compound layer on the surface of a silicon-based substrate using a metal organic compound precursor material comprises: heating the metal organic compound precursor material to have a saturated vapor pressure greater than 1 torr; The metal organic compound precursor material is introduced into a reaction chamber with the silicon-based substrate along with a carrier gas, so as to be deposited on the surface of the silicon-based substrate to form the metal organic compound layer.

[0006] In an optional embodiment, the pressure of the reaction chamber is 0.5~3 torr.

[0007] In an optional embodiment, the temperature of the silicon-based substrate during the process of depositing the metal organic compound layer and depositing the Ru thin film is 230-300°C.

[0008] In an optional embodiment, in the step of depositing a metal organic compound layer on the surface of a silicon-based substrate using a metal organic compound precursor material, a mask is used to cover a local area of ​​the silicon-based substrate, and the metal organic compound layer is deposited on the exposed surface of the silicon-based substrate.

[0009] In an optional embodiment, the metal organic compound precursor material is selected from at least one of a metal organic precursor material containing tetrakis(methylethylamino) group, a metal organic precursor material containing tetrakis(dimethylamino) group, and a metal organic precursor material containing bis(diethylamino) group.

[0010] In an optional embodiment, the metal organic compound precursor material is selected from at least one of TEMAHf, TEMAZr, TDMAT and BDEAS.

[0011] In an optional embodiment, the step of depositing a Ru thin film on the metal organic compound layer by an atomic layer deposition process comprises: A Ru precursor and an oxidant are introduced into a reaction chamber for reaction deposition, and then an inert gas is used to purge the remaining reactants, and the cycle is repeated multiple times to form the Ru film.

[0012] In an optional embodiment, the Ru precursor and the oxidant are bis(ethylcyclopentadienyl)ruthenium and oxygen, respectively.

[0013] In an optional embodiment, the total number of cycles of depositing the Ru thin film by the atomic layer deposition process does not exceed 800.

[0014] In an optional embodiment, the silicon-based substrate is made of silicon or silicon oxide.

[0015] In the Ru thin film deposition process provided in the embodiment of the present application, a metal organic compound precursor material is deposited on the surface of a silicon-based substrate to form a metal organic compound layer. Since the metal organic compound precursor material is easy to form physical adsorption with the silicon-based substrate, the bonding force between the two is better. At the same time, the organic group in the metal organic compound layer is also easy to combine with the Ru precursor used in the subsequent production of the Ru film. Therefore, the metal organic compound layer acts as an intermediate layer, which increases the adsorption density of the Ru precursor on the substrate (specifically, the metal organic compound layer), thereby improving the nucleation density. At a higher nucleation density, the nucleation efficiency is improved, thereby reducing the total number of cycles for depositing Ru thin films by the atomic layer deposition process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a flow chart of a Ru thin film deposition process in one embodiment of the present application; Figure 2 This is a graph showing the relationship between the number of cycles and the thickness of the Ru film when the Ru film is prepared using the examples and comparative examples of the present application. DETAILED DESCRIPTION

[0018] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0019] When preparing Ru thin films through related processes, Ru precursors (such as bis(ethylcyclopentadienylruthenium) Ru (EtCp) 2 ) and an oxidant for atomic layer deposition (ALD) to obtain a Ru film. The above process is not suitable for silicon-based substrates (such as Si / SiO 2 When depositing Ru film on a substrate, there is a long nucleation cycle, which may take thousands of cycles to nucleate, resulting in low process efficiency. At the same time, the long nucleation cycle will lead to local area limitation of Ru film in the initial growth stage, and because the adsorption of Ru precursor on the metal Ru core is better than that on the substrate surface, the deposited film will have a large roughness, resulting in poor uniformity and low quality of the obtained Ru film.

[0020] In order to improve at least one of the shortcomings of the above-mentioned related technologies, an embodiment of the present application provides a Ru thin film deposition process, by pre-treating the silicon-based substrate before atomic layer deposition of the Ru thin film, first forming a layer of metal organic compound layer on the surface of the silicon-based substrate, so that the subsequent atomic layer deposition of the Ru thin film has a shorter nucleation cycle, thereby improving the preparation efficiency of the Ru thin film, and is also conducive to obtaining a more uniform Ru thin film.

[0021] The Ru thin film deposition process of the embodiment of the present application is described in detail below.

[0022] Figure 1 This is a flow chart of a Ru thin film deposition process in one embodiment of the present application. Figure 1 As shown, the Ru thin film deposition process provided in the embodiment of the present application includes the following steps: Step S100 , depositing a metal organic compound precursor material on a surface of a silicon-based substrate to form a metal organic compound layer.

[0023] In the embodiment of the present application, this step is equivalent to the pretreatment process performed on the silicon-based substrate before the Ru film is deposited. The metal organic compound precursor material easily forms good physical adsorption with the silicon-based substrate, so that the formed metal organic compound layer has good bonding with the silicon-based substrate. This is due to the good bonding ability between the organic groups in the metal organic compound precursor material and the material of the silicon-based substrate. For the same reason, the metal organic compound precursor material is also easy to combine with the Ru precursor used for the subsequent preparation of the Ru film. Therefore, the metal organic compound layer can play the role of an intermediate layer, which can increase the adsorption density of the Ru precursor, thereby effectively increasing the nucleation density, improving the nucleation efficiency, shortening the nucleation cycle, and promoting the formation of a continuous film of Ru.

[0024] Optionally, the metal organic compound precursor material is selected from at least one of a metal organic precursor material containing tetrakis(methylethylamino), a metal organic precursor material containing tetrakis(dimethylamino) and a metal organic precursor material containing bis(diethylamino). 3 )(C 2 H 5 ) group, tetrakis(dimethylamino) contains four -N(CH 3 ) 2 The bis(diethylamino) group contains two -N(C 2 H 5 ) 2 Group.

[0025] Optionally, the material of the silicon-based substrate is silicon or silicon oxide. Tetrakis(methylethylamino), tetrakis(dimethylamino), and bis(diethylamino) have better bonding ability with silicon / silicon oxide, and thus are easy to combine.

[0026] Further, the metal organic compound precursor material is selected from TEMAHf (Hf[N(C 2 H 5 )(CH 3 )] 4 )、TEMAZr(Zr[N(C 2 H 5 )(CH 3 )] 4 )、TDMAT(Ti[N(CH 3 ) 2 ] 4 ) and BDEAS (SiH 2 [N(C 2 H 5 ) 2 ] 2 )

[0027] Optionally, step S100 specifically includes the following steps: Step S110, heating the metal organic compound precursor material to make its saturated vapor pressure greater than 1 torr; Step S120 , introducing a metal organic compound precursor material along with a carrier gas into a reaction chamber where a silicon-based substrate is placed, so as to deposit on the surface of the silicon-based substrate to form a metal organic compound layer.

[0028] In the embodiment of the present application, step S100 and subsequent steps S200 and S300 are all performed in the same reaction chamber. In the above step S110, the container for storing the metal organic compound precursor material can be heated to a target temperature, and the saturated vapor pressure of the metal organic compound precursor material at the target temperature is greater than 1 torr.

[0029] In step S120, the carrier gas may be argon and / or nitrogen, or other inert gas that does not participate in the reaction. The flow rate of the carrier gas may be 200-400 sccm, and the time for the carrier gas to be introduced into the reaction chamber together with the metal organic compound precursor material may be 0.5-1 s.

[0030] Optionally, during the process of depositing the metal organic compound layer, the pressure of the reaction chamber is 0.5-3 torr, and the temperature of the silicon-based substrate is 230-300° C.

[0031] Step S200: using an inert gas to purge the silicon-based substrate.

[0032] In the embodiment of the present application, argon gas and / or nitrogen gas may be used to purge the silicon-based substrate to remove the metal organic compound precursor material around the silicon-based substrate to prepare for the subsequent deposition of the Ru film.

[0033] The metal organic compound layer can be deposited on the silicon substrate by direct adsorption, that is, exposing the metal organic compound precursor material (gas) to the surface of the silicon substrate to form a single layer adsorption; it can also be formed by atomic layer deposition (ALD), for example, by repeated adsorption of metal organic compound precursor materials, inert gas purging, reducing gas plasma treatment (such as NH 3 or H 2 Plasma) to form an ultra-thin metal organic compound layer. Optionally, the thickness of the metal organic compound layer is 0.03-2.0 nm.

[0034] Step S300 , depositing a Ru thin film on the metal organic compound layer by an atomic layer deposition process.

[0035] In the embodiment of the present application, the specific method of depositing Ru film by atomic layer deposition process can refer to the conventional prior art. In the present embodiment, the step includes introducing Ru precursor and oxidant into the reaction chamber for reaction deposition, and then using inert gas (such as argon and / or nitrogen) to purge the remaining reactants, and circulate multiple times to form Ru film. The inert gas can prevent the gas phase reaction between the reactants and realize the self-saturated surface reaction. However, in some embodiments, the silicon-based substrate can be moved to contact the reactants (such as Ru precursor and oxidant) respectively. Because the reaction is self-saturated, it is usually not necessary to strictly control the temperature of the silicon-based substrate and accurately control the dosage of the Ru precursor. However, the temperature of the silicon-based substrate is preferably such that the incidental gas is neither condensed into a monolayer nor decomposed on the surface. Before the silicon-based substrate is contacted with the next reactant, the remaining reactants and reaction byproducts (if any) are removed from the surface of the silicon-based substrate, such as by purging the reaction space or by moving the silicon-based substrate. Unnecessary gaseous substances can be effectively discharged from the reaction space with the aid of inert gas, and a vacuum pump can be used to assist in purging. Optionally, the Ru precursor and the oxidant are respectively bis(ethylcyclopentadienylruthenium) (i.e., Ru(EtCp) 2 ) and oxygen. In this embodiment, Ru(EtCp) 2 It can combine well with materials such as TEMAHf, TEMAZr, TDMAT and BDEAS, so it has a higher adsorption density on the metal organic compound layer, which can increase the nucleation density, shorten the nucleation cycle and improve the deposition efficiency.

[0036] During the deposition of the Ru film, the temperature of the silicon-based substrate is maintained at 230-300°C. Since the Ru film deposition process provided in the embodiment of the present application has a shorter nucleation period, the total number of deposition cycles can be significantly reduced. Optionally, the total number of cycles for depositing the Ru film by the atomic layer deposition process does not exceed 800; through the Ru film deposition process provided in the embodiment of the present application, a Ru film with a thickness of more than 200 angstroms can be formed with a total number of cycles below 800.

[0037] In the embodiment of the present application, a mask can be used to selectively cover a portion of the silicon-based substrate, and a metal organic compound layer and a Ru film can be deposited on the exposed surface of the silicon-based substrate to form a patterned Ru film. In other optional embodiments, a Ru film can be formed first, and then a photoresist pattern is covered on the Ru film, and then the Ru film exposed by the photoresist pattern is etched to form a patterned Ru film.

[0038] The Ru thin film deposition process effect of the present application is described below in combination with various specific embodiments and comparative examples.

[0039] Example 1 TEMAHf was heated to 90°C, at which temperature its saturated vapor pressure was greater than 1 torr. Ar gas was used to carry TEMAHf vapor and injected into the reaction chamber to pretreat the surface of the silicon-based substrate. The carrier gas flow rate was 300 sccm and the injection time was 0.5 s. Then Ar gas was used to purge the surface of the silicon-based substrate to remove excess TEMAHf, allowing the substrate surface to be evenly saturated with a layer of TEMAHf to form a metal organic compound layer. The temperature of the silicon-based substrate was set at 230°C and the pressure was controlled at 0.5 torr. Ru(EtCp) was used 2 and oxygen, and deposited a Ru film on the metal organic compound layer by an atomic layer deposition process. In the above deposition step, the nucleation cycle was 68 cycles, and after 500 cycles of deposition, the thickness of the Ru film reached 269 angstroms, and the thickness uniformity was 0.43%.

[0040] Example 2 TEMAZr was heated to 92°C, at which its saturated vapor pressure was greater than 1 torr. Ar gas was used to carry TEMAZr vapor and injected into the reaction chamber to pretreat the surface of the silicon substrate. The carrier gas flow rate was 300 sccm and the injection time was 1 s. Then Ar gas was used to purge the surface of the silicon substrate to remove excess TEMAZr, allowing the substrate surface to evenly adsorb a layer of TEMAZr to form a metal organic compound layer. The temperature of the silicon substrate was set at 260°C and the pressure was controlled at 1 torr. Ru(EtCp) was used 2 and oxygen, and deposited a Ru film on the metal organic compound layer by an atomic layer deposition process. In the above deposition step, the nucleation cycle was 69 cycles, and after 500 cycles of deposition, the thickness of the Ru film reached 266 angstroms, and the thickness uniformity was 0.43%.

[0041] Example 3 TDMAT was heated to 93°C, where its saturated vapor pressure was greater than 1 torr. Ar gas was used to carry TDMAT vapor and injected into the reaction chamber to pretreat the surface of the silicon-based substrate. The carrier gas flow rate was 300 sccm and the injection time was 0.8 s. Ar gas was then used to purge the surface of the silicon-based substrate to remove excess TDMAT, allowing the substrate surface to be evenly saturated with a layer of TDMAT to form a metal organic compound layer. The temperature of the silicon-based substrate was set at 280°C and the pressure was controlled at 2 torr. Ru(EtCp) was used 2 and oxygen, and deposited a Ru film on the metal organic compound layer by an atomic layer deposition process. In the above deposition step, the nucleation cycle was 77 cycles, and after 500 cycles of deposition, the thickness of the Ru film reached 253 angstroms, and the thickness uniformity was 0.45%.

[0042] Example 4 BDEAS was heated to 95°C, where its saturated vapor pressure was greater than 1 torr. Ar gas was used to carry BDEAS vapor and injected into the reaction chamber to pretreat the surface of the silicon substrate. The carrier gas flow rate was 300 sccm and the injection time was 1 s. Ar gas was then used to purge the surface of the silicon substrate to remove excess BDEAS, allowing the substrate surface to be evenly saturated with a layer of BDEAS to form a metal organic compound layer. The temperature of the silicon substrate was set at 300°C and the pressure was controlled at 3 torr. Ru(EtCp) was used 2 and oxygen, and deposited a Ru film on the metal organic compound layer by an atomic layer deposition process. In the above deposition step, the nucleation cycle was 122 cycles, and after 500 cycles of deposition, the thickness of the Ru film reached 227 angstroms, and the thickness uniformity was 0.49%.

[0043] Comparative Example 1 The difference from Example 1 is that the silicon-based substrate is not pretreated, and the Ru film is directly deposited on the silicon-based substrate using an atomic layer deposition process.

[0044] Comparative Example 2 The difference from Example 1 is that the step of depositing the metal organic compound layer using TEMAHf is omitted, and the silicon-based substrate is treated with ozone for 10 minutes, wherein the ozone concentration is 280 g / m 3 , with a flow rate of 5000 sccm. Thereafter, the Ru film was deposited using an atomic layer deposition process.

[0045] Comparative Example 3 The difference from Example 1 is that the step of depositing the metal organic compound layer using TEMAHf is omitted, and the silicon-based substrate is treated with ammonia for 10 minutes, wherein the ammonia flow rate is 5000 sccm. Thereafter, the Ru film is deposited using an atomic layer deposition process.

[0046] Comparative Example 4 The difference from Example 1 is that the step of depositing the metal organic compound layer using TEMAHf is omitted, and the silicon-based substrate is first treated with ozone for 10 minutes, and then treated with ammonia for 10 minutes, wherein the ozone concentration is 280g / m 3 , the flow rate is 5000 sccm, and the ammonia flow rate is 5000 sccm. Thereafter, the Ru film is deposited using an atomic layer deposition process.

[0047] Comparative Example 5 The difference from Example 1 is that the step of depositing the metal organic compound layer using TEMAHf is omitted, and the silicon-based substrate is first treated with ammonia for 10 minutes, and then treated with ozone for 10 minutes, wherein the ozone concentration is 280g / m3 , the flow rate is 5000 sccm, and the ammonia flow rate is 5000 sccm. Thereafter, the Ru film is deposited using an atomic layer deposition process.

[0048] Figure 2 This is a graph showing the relationship between the number of cycles and the thickness of the Ru film when the Ru film is prepared using the examples and comparative examples of the present application. Figure 2 In the figure, the ordinate is the thickness of the Ru film (THK), in angstroms, and the abscissa is the number of cycles in the atomic layer deposition process.

[0049] like Figure 2 As shown, in Comparative Example 1 in which the silicon-based substrate was not pretreated, the nucleation cycle was 1053 cycles, and after 1400 cycles of deposition, the thickness reached 213 angstroms, and the thickness uniformity of the Ru film was 2.15%.

[0050] In comparative example 2, the nucleation period is 1043 cycles, and after 1400 cycles of deposition, the thickness reaches 216 angstroms, and the thickness uniformity of the Ru film is 2.08%.

[0051] In comparative example 3, the nucleation period is 1038 cycles, and after 1400 cycles of deposition, the thickness reaches 225 angstroms, and the thickness uniformity of the Ru film is 2.21%.

[0052] In comparative example 4, the nucleation period is 1041 cycles, and after 1400 cycles of deposition, the thickness reaches 217 angstroms, and the thickness uniformity of the Ru film is 2.37%.

[0053] In comparative example 5, the nucleation period is 977 cycles, and after 1400 cycles of deposition, the thickness reaches 257 angstroms, and the thickness uniformity of the Ru film is 2.01%.

[0054] It can be seen that in each comparative example, the nucleation period of the deposited Ru film is relatively long. For the film thickness deposited similarly, the total number of deposition cycles in each comparative example reaches more than one thousand times, which is significantly higher than the total number of cycles in Examples 1 to 4. Therefore, the Ru film deposition process of the embodiment of the present application can effectively improve the deposition efficiency of the Ru film. In addition, from the perspective of thickness uniformity, the thickness uniformity of the Ru film in each embodiment of the present application is less than 0.5%. The lower the value, the more uniform the thickness of the Ru film. The thickness uniformity of the Ru film obtained in Comparative Examples 1 to 5 is more than 2%. Therefore, from the perspective of thickness uniformity, the Ru film deposition process provided in the embodiment of the present application can effectively improve the quality of the Ru film.

[0055] In summary, the embodiment of the present application provides a Ru thin film deposition process, including using a metal organic compound precursor material to deposit on the surface of a silicon-based substrate to form a metal organic compound layer; using an inert gas to purge the silicon-based substrate; and depositing a Ru thin film on the metal organic compound layer by an atomic layer deposition process. Since the metal organic compound precursor material can easily form physical adsorption with the silicon-based substrate, the bonding force between the two is relatively good. At the same time, the organic groups in the metal organic compound layer are also easy to combine with the Ru precursor used in the subsequent preparation of the Ru thin film. Therefore, the metal organic compound layer acts as an intermediate layer, which increases the adsorption density of the Ru precursor on the substrate (specifically, the metal organic compound layer), thereby increasing the nucleation density. At a higher nucleation density, the nucleation efficiency is improved, thereby reducing the total number of cycles for depositing Ru thin films by the atomic layer deposition process.

[0056] The above description is only a specific embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A Ru thin film deposition process, characterized in that: include: Depositing a metal organic compound layer on the surface of a silicon-based substrate using a metal organic compound precursor material; Purging the silicon-based substrate with an inert gas; A Ru thin film is deposited on the metal organic compound layer by an atomic layer deposition process.

2. The Ru thin film deposition process according to claim 1, characterized in that: The step of depositing a metal organic compound layer on the surface of a silicon-based substrate using a metal organic compound precursor material comprises: heating the metal organic compound precursor material so that its saturated vapor pressure is greater than 1 torr; The metal organic compound precursor material is introduced into a reaction chamber with the silicon-based substrate along with a carrier gas, so as to be deposited on the surface of the silicon-based substrate to form the metal organic compound layer.

3. The Ru thin film deposition process according to claim 2, characterized in that: The pressure of the reaction chamber is 0.5~3torr.

4. The Ru thin film deposition process according to claim 2, characterized in that: The temperature of the silicon-based substrate during the process of depositing the metal organic compound layer and the Ru film is 230-300° C.

5. The Ru thin film deposition process according to claim 1, characterized in that: In the step of depositing a metal organic compound layer on the surface of a silicon-based substrate using a metal organic compound precursor material, a mask is used to cover a local area of ​​the silicon-based substrate, and the metal organic compound layer is deposited on the exposed surface of the silicon-based substrate.

6. The Ru thin film deposition process according to claim 1, characterized in that: The metal organic compound precursor material is selected from at least one of a metal organic precursor material containing a tetrakis(methylethylamino) group, a metal organic precursor material containing a tetrakis(dimethylamino) group, and a metal organic precursor material containing a bis(diethylamino) group.

7. The Ru thin film deposition process according to claim 6, characterized in that: The metal organic compound precursor material is selected from at least one of TEMAHf, TEMAZr, TDMAT and BDEAS.

8. The Ru thin film deposition process according to any one of claims 1 to 7, characterized in that: The step of depositing a Ru thin film on the metal organic compound layer by an atomic layer deposition process comprises: A Ru precursor and an oxidant are introduced into a reaction chamber for reaction deposition, and then an inert gas is used to purge the remaining reactants, and the cycle is repeated multiple times to form the Ru film.

9. The Ru thin film deposition process according to claim 8, characterized in that: The Ru precursor and the oxidant are bis(ethylcyclopentadienyl)ruthenium and oxygen respectively.

10. The Ru thin film deposition process according to claim 8, characterized in that: The total number of cycles for depositing the Ru thin film by the atomic layer deposition process does not exceed 800.

11. The Ru thin film deposition process according to any one of claims 1 to 7, characterized in that: The silicon-based substrate is made of silicon or silicon oxide.

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