Method for etching copper by plasma and semiconductor process equipment

Abstract

The invention provides a plasma copper etching method and semiconductor process equipment. According to the method for etching the copper through the plasma, firstly, a copper layer is modified through first process gas, the surface of the copper layer is modified into cuprous chloride, then, second process gas reacts with the cuprous chloride to generate cuprous nitride, and the reaction is continuously carried out in the direction of etching the copper layer till etching of the copper layer is completed. The cuprous nitride is low in melting and boiling point and is easy to volatilize in the etching process, so that the etching uniformity is improved, a process chamber is prevented from being polluted, and the process stability is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for plasma etching of copper and semiconductor process equipment. Background Technology

[0002] In the integrated circuit chip manufacturing (packaging) process, copper interconnects are gradually replacing aluminum interconnects to improve electrical performance. However, since the boiling points of copper chloride (993℃) and cuprous chloride (1490℃) are significantly higher than those of aluminum chloride (180℃), if the existing chlorine plasma etching method for aluminum is used to etch copper (Cu) using plasma etching, the following problems will occur: ① The etching byproducts such as copper chloride and cuprous chloride are difficult to volatilize, resulting in poor etching uniformity; ② The redeposition of the generated copper chloride or cuprous chloride will easily lead to contamination of the process chamber.

[0003] Furthermore, in the dry etching process of copper, halogens still dominate, and the byproducts include copper compounds and copper particles formed by bombardment sputtering. For copper compounds, such as copper fluoride by using fluorine (F)-based gases for etching, the resulting copper fluoride byproduct has a boiling point of 1449°C and remains difficult to volatilize. Copper particles not only form a conductive layer, interfering with RF feed, but also pose a risk of metal contamination and adhere to the chamber sidewalls, significantly impacting process stability. Therefore, how to perform plasma etching of copper while ensuring process stability is a pressing issue that needs to be addressed. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for plasma etching of copper and semiconductor process equipment to alleviate the above-mentioned technical problems.

[0005] In a first aspect, embodiments of the present invention provide a method for plasma etching of copper, wherein a preset substrate is provided, the method comprising: Modification step: The copper layer of the preset substrate is modified with the first process gas to modify the surface of the copper layer into cuprous chloride; First etching step: The second process gas reacts with cuprous chloride to generate cuprous nitride, which is then used to etch the copper layer; Desorption step: After the copper layer etching is completed, a third process gas is used to desorb the preset substrate.

[0006] Optionally, the first process gas includes a first modified gas; wherein the first modified gas is a gas containing chlorine.

[0007] Optionally, the first process gas further includes a first dilution gas; wherein the flow rate ratio of the first modified gas and the first dilution gas is less than 1.

[0008] Optionally, the second process gas includes an etching gas and a reducing gas; wherein the etching gas is nitrogen and the reducing gas is a nitrogen-containing gas.

[0009] Optionally, the second process gas further includes a second dilution gas; wherein, in the second process gas, the flow rate of the second dilution gas is higher than the flow rate of the etching gas and the flow rate of the reducing gas.

[0010] Optionally, the modification step and the first etching step are alternated in a cycle.

[0011] Optionally, prior to the modification step, the method further includes: a first ignition step: ignition is performed using a fourth process gas; wherein the fourth process gas includes a second modified gas and a third dilution gas, and the flow rate ratio of the second modified gas and the third dilution gas is less than 1.

[0012] Secondly, embodiments of the present invention also provide a method for plasma etching of copper, providing a preset substrate, the method comprising: Second ignition step: Ignition is initiated using the fifth process gas; The second etching step: The copper layer of the preset substrate is etched using the sixth process gas; Cleaning phase: The process chamber is cleaned using the seventh process gas.

[0013] Thirdly, embodiments of the present invention also provide a semiconductor process apparatus, including a process chamber and a controller; wherein the controller is used to etch a copper layer of a preset substrate in the process chamber using the methods described in the first or second aspects above.

[0014] Fourthly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the methods described in the first or second aspect.

[0015] The embodiments of the present invention bring the following beneficial effects: This invention provides a method for plasma etching of copper and semiconductor process equipment. In the method, there are three steps: a modification step: using a first process gas to modify a copper layer on a preset substrate to form cuprous chloride on the surface; a first etching step: using a second process gas to react with cuprous chloride to generate cuprous nitride for etching the copper layer; and a desorption step: after the copper layer etching is complete, using a third process gas to desorb the preset substrate. In this plasma etching method, the copper layer is first modified with a first process gas to form cuprous chloride on its surface, and then the second process gas reacts with the cuprous chloride to generate cuprous nitride. This allows the reaction to continue in the direction of etching the copper layer until etching is complete. Because cuprous nitride has a low melting and boiling point, it easily volatilizes during etching, thereby improving etching uniformity, avoiding contamination of the process chamber, and improving process stability.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A flowchart of a method for plasma etching copper provided in an embodiment of the present invention; Figure 2 A flowchart of another method for plasma etching copper provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a process chamber provided in an embodiment of the present invention; Figure 4 A schematic diagram of the coating on the inner side of a ceramic cylinder provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a ceramic cylinder outer chamber temperature control module provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To facilitate understanding of this embodiment, the embodiments of the present invention will be described in detail below.

[0022] Example 1 This invention provides a method for plasma etching of copper, providing a preset substrate, such as... Figure 1 As shown, the method includes the following steps: Step S102, Modification step: The copper layer of the preset substrate is modified using the first process gas to modify the surface of the copper layer into cuprous chloride.

[0023] The first process gas includes a first modifying gas, which is a chlorine-containing gas, including but not limited to chlorine and boron trichloride, to utilize the strong oxidizing properties of chlorine to modify the surface of the copper layer into cuprous chloride. The first process gas also includes a first diluting gas, which is an inert gas, including but not limited to argon, neon, and krypton. Furthermore, to ensure the modification effect of the copper layer, the proportion of the first diluting gas in the first process gas should be higher than that of the first modifying gas; that is, the flow ratio of the first modifying gas to the first diluting gas is less than 1.

[0024] It should be noted that in the modification step, in addition to modifying the surface of the copper layer to cuprous chloride, a small amount of copper chloride may also be included in some scenarios.

[0025] Step S104, First etching step: The second process gas is used to react with cuprous chloride to generate cuprous nitride, so as to etch the copper layer.

[0026] The second process gas includes an etching gas; in this embodiment, the etching gas is nitrogen. Furthermore, the second process gas also includes a reducing gas, which is a nitrogen-containing gas, including but not limited to ammonia, hydroazide acid, and hydrazine vapor. In this embodiment, ammonia is preferred, as it provides a reducing atmosphere, allowing the small amount of divalent copper generated in the modification step to be reduced to monovalent copper. Additionally, the second process gas also includes a second dilution gas, which is an inert gas, including but not limited to argon, neon, and krypton.

[0027] Furthermore, to ensure effective etching, the flow rate of the second dilution gas in the second process gas is higher than that of the etching gas and the reducing gas, thus avoiding excessive etching that could lead to poor control. Therefore, in the etching step, the second process gas, composed of the second dilution gas, nitrogen, and ammonia, reacts with cuprous chloride to generate cuprous nitride, thereby achieving copper layer etching.

[0028] Step S106, Desorption step: After the copper layer etching is completed, the preset substrate is desorbed using a third process gas.

[0029] In practical applications, during the copper etching process, the pre-set substrate needs to be adsorbed onto a wafer carrier such as an electrostatic chuck for sufficient heat dissipation and cooling. Therefore, after the copper etching is completed, desorption is required. In this embodiment of the invention, a third process gas is used to desorb the pre-set substrate. The third process gas is an inert gas, including but not limited to argon, neon, and krypton, and can be specifically set according to actual conditions.

[0030] The plasma etching method for copper provided in this invention first modifies the copper layer using a first process gas to transform the surface of the copper layer into cuprous chloride. Then, a second process gas reacts with the cuprous chloride to generate cuprous nitride, allowing the reaction to continue in the direction of etching the copper layer until the etching is complete. Since cuprous nitride has a low melting and boiling point, it is easily volatilized during the etching process, thereby not only improving the etching uniformity but also avoiding contamination of the process chamber and improving process stability.

[0031] In one implementation, the modification step and the first etching step are alternated in a loop. During the copper layer etching process, the alternating loop of the modification step and the first etching step further ensures the etching effect of the copper layer. Specifically, the alternating loop can be performed in the pattern of modification step—first etching step—modification step—first etching step, or it can be performed in the pattern of one modification step followed by multiple first etching steps, depending on the actual situation.

[0032] In one embodiment, prior to the modification step, the method further includes: a first ignition step: ignition is performed using a fourth process gas; wherein the fourth process gas includes a second modified gas and a third dilution gas, and the flow rate ratio of the second modified gas and the third dilution gas is less than 1.

[0033] In practical applications, the second modifying gas is a chlorine-containing gas, including but not limited to chlorine and boron trichloride, and the third dilution gas is an inert gas, including but not limited to argon, neon and krypton, so as to modify the surface of the copper layer during the ignition process and further ensure the etching uniformity of the copper layer.

[0034] It should be noted that although both the first ignition step and the modification step can modify the copper layer surface, the modification effect can only be carried out stably after the radio frequency is stabilized because the ignition step requires radio frequency ignition and is accompanied by radio frequency reflection. Therefore, this process is called the first ignition step.

[0035] Furthermore, prior to the first etching step, the method includes a stabilization step to stabilize the atmosphere in the process chamber, ensuring that the atmosphere in the process chamber is consistent with that in the subsequent first etching step, thereby further guaranteeing the etching uniformity of the copper layer. In the stabilization step, the process gases used include a third modified gas and a fourth dilution gas, and the flow rate ratio of the third modified gas to the fourth dilution gas is less than 1.

[0036] In practical applications, the third modifying gas is a chlorine-containing gas, including but not limited to chlorine and boron trichloride, and the fourth dilution gas is an inert gas, including but not limited to argon, neon and krypton, so as to modify the copper layer surface before ignition, ensuring the modification effect of cuprous chloride, and further ensuring the etching uniformity of the copper layer.

[0037] In summary, the copper layer etching process mainly includes a stabilization step, a first ignition step, a modification step, a first etching step, and a desorption step, arranged sequentially. Each step also has corresponding process parameters, which are detailed below: (1) Stabilization step: The chamber pressure is 1 mTorr~1000 mTorr. If the chamber pressure is too low, it will be easy to extinguish after ignition. If the chamber pressure is too high, it will lead to failure to ignite. The upper electrode power and lower electrode power are 0. The flow rate of the third modifying gas, such as chlorine, is 5 sccm~500 sccm to modify the surface of the copper layer into cuprous chloride. The flow rate of the fourth dilution gas, such as argon, is 5 sccm~500 sccm. If the flow rates of chlorine and argon are too low or too high, the chamber pressure will be uncontrollable. In addition, the flow rate of argon is higher than that of chlorine to avoid the etching effect of the third modifying gas being too strong and failing to achieve the purpose of modification. The process time of this step is 1s~100s. If the process time is too short, the chamber atmosphere will be unstable. If the process time is too long, the production capacity will be reduced.

[0038] (2) First Ignition Step: The purpose is to stabilize the RF system. Due to potentially large RF reflections, a certain amount of time is required for stabilization. Furthermore, in the ignition step, the chamber pressure is 1 mTorr to 1000 mTorr. If the chamber pressure is too low, it will easily extinguish after ignition; if the chamber pressure is too high, it will prevent ignition. The lower electrode power is 0, and the upper electrode power is 100W to 10000W. If the upper electrode power is too low, it will prevent ignition; if the upper electrode power is too high, the equipment will not support it. Additionally, in the fourth process gas, the flow rate of the second modifying gas, such as chlorine, is 5 sccm to 500 sccm, and the flow rate of the third diluting gas, such as argon, is 5 sccm to 500 sccm. If the flow rates of chlorine and argon are too low or too high, the chamber pressure will be uncontrollable. Also, the flow rate of argon is higher than that of chlorine to avoid excessive etching by the second modifying gas, which would prevent the modification from being achieved. The process time for this step is 1s to 100s. If the process time is too short, the radio frequency reflection will not reach stability. If the process time is too long, the production capacity will be reduced and too much modification will occur, which will reduce the etching effect of the copper layer.

[0039] (3) Modification step: The chamber pressure is 1 mTorr~1000 mTorr. If the chamber pressure is too low, it will easily extinguish after ignition. If the chamber pressure is too high, it will cause extinguishing. The lower electrode power is 0, and the upper electrode power is 100W~10000W. If the upper electrode power is too low, it will cause extinguishing. If the upper electrode power is too high, it will cause the equipment to not support it. In the first process gas, the flow rate of the first modifying gas, such as chlorine, is 5 sccm~500 sccm, and the flow rate of the first dilution gas, such as argon, is 5 sccm~500 sccm. If the flow rates of chlorine and argon are too low or too high, the chamber pressure cannot be controlled, and the modification effect will also be affected. In addition, the process time of this step is 1s~100s. If the process time is too short, the modification of the copper layer will not be fully carried out, reducing the modification effect and thus reducing the etching effect of the copper layer. If the process time is too long, the production capacity will be reduced.

[0040] (4) First etching step: The chamber pressure is 1 mTorr~1000 mTorr. If the chamber pressure is too low or too high, it will easily extinguish after ignition. Considering that the plasma ionization is sufficient when the upper electrode power is high during the etching process, a certain etching rate can be guaranteed. However, if it is too high, the equipment will not support it. The higher the lower electrode power, the stronger the physical bombardment and the faster the etching rate, but the greater the bombardment damage. Therefore, in the first etching step of this embodiment, the lower electrode power is 0~200W and the upper electrode power is 100W~10000W. In addition, in the second process gas, the flow rate of the etching gas nitrogen is 5 sccm~500 sccm, the flow rate of the reducing gas ammonia is 5 sccm~500 sccm, and the flow rate of the second dilution gas such as argon is 5 sccm~500 sccm. If the flow rates of nitrogen, ammonia and argon are too low or too high, the chamber pressure will be uncontrollable and the etching effect will be affected. Furthermore, the process time for this step is 1s to 100s. If the process time is too short, the etching effect of the copper layer will be poor. If the process time is too long, the production capacity will be reduced.

[0041] (5) Desorption step: The chamber pressure is 1 mTorr to 1000 mTorr. If the chamber pressure is too low or too high, it will easily cause the ignition to extinguish after ignition. The lower electrode power is 0. If the upper electrode power is too low, it will cause the ignition to extinguish. If the upper electrode power is too high, it will cause the equipment to not support it. Therefore, the upper electrode power is 100W to 10000W. The third process gas contains dilution gas such as argon, with a flow rate of 5 sccm to 500 sccm. If the argon flow rate is too low or too high, it will cause the chamber pressure to be uncontrollable. In addition, the process time of this step is 1s to 100s. If the process time is too short, it will cause insufficient charge release. If the process time is too long, it will cause a reduction in production capacity, or even cause the charge to be re-adsorbed in the opposite direction, reducing the desorption effect.

[0042] For example, in the stabilization step, the chamber pressure is 5 mTorr, the upper electrode power is 0 W, the lower electrode power is 0 W, the chlorine flow rate is 50 sccm, the argon flow rate is 50 sccm, the nitrogen flow rate is 0 sccm, the ammonia flow rate is 0 sccm, and the process duration is 5 s; in the first ignition step, the chamber pressure is 5 mTorr, the upper electrode power is 2500 W, the lower electrode power is 0 W, the chlorine flow rate is 50 sccm, the argon flow rate is 50 sccm, the nitrogen flow rate is 0 sccm, the ammonia flow rate is 0 sccm, and the process duration is 5 s; in the modification step, the chamber pressure is 5 mTorr, the upper electrode power is 2500 W, the lower electrode power is 0 W, and the chlorine flow rate is 50 sccm. In the first etching step, the chamber pressure is 5 mTorr, the upper electrode power is 2500 W, the lower electrode power is 75 W, the chlorine flow rate is 0 sccm, the argon flow rate is 50 sccm, the nitrogen flow rate is 25 sccm, the ammonia flow rate is 25 sccm, and the process duration is 5 s. In the desorption step, the chamber pressure is 5 mTorr, the upper electrode power is 2500 W, the lower electrode power is 0 W, the chlorine flow rate is 0 sccm, the argon flow rate is 50 sccm, the nitrogen flow rate is 0 sccm, the ammonia flow rate is 0 sccm, and the process duration is 5 s.

[0043] In addition, the melting and boiling points of various materials are compared in Table 1 below: Table 1

[0044] Therefore, as shown in the table above, the copper layer is first modified in a modification step to form cuprous chloride on its surface. Then, in the first etching step, the second process gas reacts with the cuprous chloride to generate cuprous nitride, allowing the reaction to continue in the direction of etching the copper layer until the etching is complete. Furthermore, this invention avoids using copper chloride, cuprous chloride, and copper fluoride, which have high melting and boiling points. Instead, cuprous nitride is used. Because cuprous nitride has a low melting and boiling point, it easily decomposes at high temperatures, making it easily volatilized during etching. This not only improves etching uniformity but also avoids contaminating the process chamber and improves process stability.

[0045] Example 2 For plasma etching of copper, besides modifying the copper using a first process gas such as chlorine, as described above, direct etching is also possible. Based on the above method embodiments, this invention provides another method for plasma etching of copper, providing a pre-defined substrate, such as... Figure 2 As shown, the method includes the following steps: Step S202, Second Ignition Step: Ignition is performed using the fifth process gas.

[0046] The fifth process gas includes argon, nitrogen, hydrogen, and ammonia. In practical applications, argon not only serves as a dilution agent but also assists in ignition. Nitrogen provides a large amount of nitrogen to facilitate the chemical reaction towards the formation of cuprous nitride; therefore, nitrogen can be replaced with other nitrogen-containing gases. Hydrogen provides a reducing atmosphere to prevent cuprous nitride from being oxidized to copper nitride; therefore, hydrogen can be replaced with other reducing gases such as nitric oxide (NO) and carbon monoxide (CO). Ammonia provides more reactive nitrogen and hydrogen than nitrogen and hydrogen (the N-N triple bond in nitrogen is very stable and requires significant power to dissociate); therefore, nitrogen can be replaced with hydroazide acid and hydrazine vapor, etc. The specific fifth process gas can be set according to the actual situation.

[0047] Step S204, Second etching step: The copper layer of the preset substrate is etched using the sixth process gas.

[0048] Similarly, the sixth process gas includes argon, nitrogen, hydrogen, and ammonia. In practical applications, argon not only serves as a dilution agent but also assists in ignition. Nitrogen provides a large amount of nitrogen to facilitate the chemical reaction towards the formation of cuprous nitride; therefore, nitrogen can be replaced with other nitrogen-containing gases. Hydrogen provides a reducing atmosphere to prevent cuprous nitride from being oxidized to copper nitride; therefore, hydrogen can be replaced with other reducing gases, such as nitric oxide (NO) and carbon monoxide (CO). Ammonia provides more reactive nitrogen and hydrogen than nitrogen and hydrogen (the N-N triple bond in nitrogen is very stable and requires significant power to dissociate); therefore, nitrogen can be replaced with hydroazide acid and hydrazine vapor, etc. The specific sixth process gas can be set according to the actual situation.

[0049] Step S206, Cleaning stage: The process chamber is cleaned using the seventh process gas.

[0050] Specifically, the cleaning stage includes a sequentially arranged extraction step, stabilization step, and dry cleaning step. The extraction step is primarily used to remove residues inside the process chamber after etching. The stabilization step stabilizes the environment of the process chamber, including but not limited to atmosphere and chamber pressure. The dry cleaning step modifies the copper particles within the process chamber to prevent contamination from copper particles generated during etching. It should be noted that a corresponding seventh process gas is also set for each of the extraction, stabilization, and dry cleaning steps during the cleaning stage; details will be provided later.

[0051] In addition, a stabilization step is provided before the second ignition step to stabilize the atmosphere in the process chamber. For ease of explanation, the stabilization step before the second ignition step is referred to as the first stabilization step, and the stabilization step in the cleaning stage is referred to as the second stabilization step. Furthermore, to easily distinguish the process steps of different embodiments, the ignition step and etching step in Embodiment 1 are referred to as the first ignition step and the first etching step, and the ignition step and etching step in Embodiment 2 are referred to as the second ignition step and the second etching step.

[0052] Therefore, the plasma direct etching method for copper includes a first stabilization step, a second ignition step, a second etching step, an extraction step, a second stabilization step, and a dry cleaning step, arranged sequentially; the process parameters for each step are as follows: (1) First stabilization step: used to stabilize the chamber atmosphere so that the chamber atmosphere of the process chamber is consistent with that of the second etching step. The process parameters include, but are not limited to: the upper electrode power and the lower electrode power are 0, and the chamber pressure is 1 mTorr to 1000 mTorr. If the chamber pressure is too low or too high, it will lead to failure to start the ignition. In addition, the chamber pressure is too high or too low, which will also affect the process results, such as the etching rate becoming faster or slower. In this embodiment of the invention, 15 mTorr is preferred. In addition, the process gases and their flow rates are as follows: the flow rate of argon is 40 sccm, the flow rate of nitrogen is 5 sccm, the flow rate of hydrogen is 5 sccm, the flow rate of ammonia is 5 sccm, the flow rate of ammonium fluoride is 0, the flow rate of hydrogen peroxide is 0, and the flow rate of ethanol is 0.

[0053] Argon not only serves as a dilution agent but also assists in ignition, thereby stabilizing the second ignition step through the process gas of the first stabilization step, ensuring process stability when a large amount of gas is introduced in the second etching step. Furthermore, in addition to argon, the flow rates of other gases such as nitrogen, hydrogen, and ammonia meet the requirement of 5 sccm to 10 sccm, and the total flow rate of nitrogen, hydrogen, and ammonia does not exceed half the flow rate of argon.

[0054] In practical applications, nitrogen is used to provide a large amount of N, which facilitates the chemical reaction towards the formation of cuprous nitride. Therefore, nitrogen can be replaced with other nitrogen-containing gases. Hydrogen is used to provide a reducing atmosphere to prevent cuprous nitride from being oxidized to copper nitride. Therefore, hydrogen can be replaced with other reducing gases, such as nitric oxide (NO) and carbon monoxide (CO). Ammonia is used to provide N and H, which are more reactive than nitrogen and hydrogen (the N-N triple bond in nitrogen is very stable and requires a large amount of power to dissociate). Therefore, nitrogen can be replaced with hydroazide acid and hydrazine vapor, etc. The specific process gases in the first stabilization step can be set according to the actual situation.

[0055] It should be noted that since ammonium fluoride, hydrogen peroxide, and ethanol are mainly used to clean up byproducts, their flow rates are 0 in the first stabilization step.

[0056] (2) Second ignition step: used for ignition, ionizing the stabilized gas into plasma. The process parameters include, but are not limited to: the upper electrode power range is 300W~1500W, preferably 700W in this embodiment to ensure stable ignition; the lower electrode power is 0 to prevent direct etching; the chamber pressure is 10mTorr~50mTorr. If the chamber pressure is too low, ignition will easily be extinguished after ignition; if the chamber pressure is too high, ignition will fail. Furthermore, excessively high or low chamber pressure will affect the process results, such as increasing or decreasing the etching rate. In this embodiment, 15mTorr is preferred. In addition, the process gases and their flow rates are as follows: argon flow rate is 40 sccm, nitrogen flow rate is 5 sccm, hydrogen flow rate is 5 sccm, ammonia flow rate is 5 sccm, ammonium fluoride flow rate is 0, hydrogen peroxide flow rate is 0, and ethanol flow rate is 0. It should be noted that the argon flow rate ranges from 20 sccm to 200 sccm. The higher the argon ratio, the more stable the ignition.

[0057] Similarly, in the process gas of the second ignition step, argon not only serves as a dilution agent but also assists in ignition, ensuring process stability when a large amount of gas is introduced in the second etching step. Furthermore, in addition to argon, the flow rates of other gases such as nitrogen, hydrogen, and ammonia meet the requirement of 5 sccm to 10 sccm, and the total flow rate of nitrogen, hydrogen, and ammonia does not exceed half the flow rate of argon.

[0058] In practical applications, nitrogen is used to provide a large amount of N, which facilitates the chemical reaction towards the formation of cuprous nitride. Therefore, nitrogen can be replaced with other nitrogen-containing gases. Hydrogen is used to provide a reducing atmosphere to prevent cuprous nitride from being oxidized to copper nitride. Therefore, hydrogen can be replaced with other reducing gases, such as nitric oxide (NO) and carbon monoxide (CO). Ammonia is used to provide N and H, which are more reactive than nitrogen and hydrogen (the N-N triple bond in nitrogen is very stable and requires a large amount of power to dissociate). Therefore, nitrogen can be replaced with hydroazide acid and hydrazine vapor, etc. The specific process gases in the first stabilization step can be set according to the actual situation.

[0059] It should be noted that since ammonium fluoride, hydrogen peroxide, and ethanol are mainly used to clean up byproducts, their flow rates are 0 in the second ignition step.

[0060] (3) Second etching step: The plasma after ignition is used to etch the preset substrate under the traction of the lower electrode. The process parameters include, but are not limited to: the power range of the upper electrode is 300W~2000W, and the preferred power in this embodiment is 700W to avoid quenching; the power range of the lower electrode is 20W~500W, and the preferred power in this embodiment is 30W; the chamber pressure is 4mTorr~30mTorr, which can ensure stable ignition and desorb or remove the generated byproducts at a lower pressure. If the chamber pressure is too high or too low, it will not only cause quenching, but also affect the process results, such as the etching rate becoming faster or slower. Therefore, the preferred pressure in this embodiment is 15mTorr; in addition, the process gases and their flow rates are as follows: the flow rate of argon is 30sccm, the flow rate of nitrogen is 15sccm, the flow rate of hydrogen is 15sccm, the flow rate of ammonia is 10sccm, the flow rate of ammonium fluoride is 0, the flow rate of hydrogen peroxide is 0, and the flow rate of ethanol is 0. It should be noted that the flow rate of argon gas is in the range of 20 sccm to 200 sccm, which not only forms physical bombardment of Ar ions, but also ensures the stability of ignition.

[0061] Argon not only serves as a dilution agent but also assists in ignition, ensuring process stability when a large amount of gas is introduced in the second etching step. Furthermore, in addition to argon, the flow rates of other gases such as nitrogen, hydrogen, and ammonia are between 5 sccm and 50 sccm, and the total flow rate of nitrogen, hydrogen, and ammonia does not exceed half the flow rate of argon.

[0062] Similarly, nitrogen is used to provide a large amount of N, which facilitates the chemical reaction towards the formation of cuprous nitride. Therefore, nitrogen can be replaced with other nitrogen-containing gases. Hydrogen is used to provide a reducing atmosphere to prevent cuprous nitride from being oxidized to copper nitride. Therefore, hydrogen can be replaced with other reducing gases, such as nitric oxide (NO) and carbon monoxide (CO). Ammonia is used to provide N and H, which are more reactive than nitrogen and hydrogen (the N-N triple bond in nitrogen is very stable and requires a large amount of power to dissociate). Therefore, nitrogen can be replaced with hydroazide acid and hydrazine vapor, etc. The specific process gases in the second etching step can be set according to the actual situation.

[0063] It should be noted that since ammonium fluoride, hydrogen peroxide, and ethanol are mainly used to clean up byproducts, their flow rates are 0 in the second etching step.

[0064] (4) Evacuation Step: After etching, an inert gas or auxiliary gas is used for purging to remove residues inside the process chamber. Process parameters include, but are not limited to: the power of the upper electrode and the power of the lower electrode are both 0; the chamber pressure is 20 mTorr to 50 mTorr to allow for appropriate gas flow to carry away residual substances, preferably 30 mTorr in this embodiment of the invention; in addition, the process gases and their flow rates are as follows: argon flow rate is 0, nitrogen flow rate is 100 sccm, hydrogen flow rate is 100 sccm, ammonia flow rate is 0, ammonium fluoride flow rate is 0, hydrogen peroxide flow rate is 0, and ethanol flow rate is 0. It should be noted that nitrogen and hydrogen are mainly used to carry away suspended or unadsorbed byproduct particles; among them, nitrogen, as the main flowing gas, has a flow rate range of 50 sccm to 200 sccm to carry away residual substances, and hydrogen has a flow rate range of 50 sccm to 200 sccm to assist in carrying away residual substances.

[0065] (5) Second stabilization step: This step is used to clean the process chamber after the process to stabilize the ratio of the new process gas and the chamber pressure. The process parameters include, but are not limited to: the power of the upper electrode and the power of the lower electrode are both 0; the chamber pressure is 6 mTorr to 20 mTorr to ensure stable start-up of the subsequent dry cleaning step. In this embodiment of the invention, 10 mTorr is preferred. In addition, the process gases and their flow rates are as follows: the flow rate of argon is 100 sccm, the flow rate of nitrogen is 0, the flow rate of hydrogen is 0, the flow rate of ammonia is 0, the flow rate of ammonium fluoride is 10 sccm, the flow rate of hydrogen peroxide is 40 sccm, and the flow rate of ethanol is 5 sccm.

[0066] It should be noted that the flow rate of argon is in the range of 50 sccm to 200 sccm, used to assist in the ignition of ammonium fluoride, hydrogen peroxide, and ethanol, which are difficult to ignite. In addition, the total flow rate of the mixed gas composed of argon, hydrogen peroxide, ammonium fluoride, and ethanol is 100 sccm to 400 sccm, and the flow rate ratio is (18 to 30): 8: 2: 1. In particular, ammonium fluoride, hydrogen peroxide, and ethanol can react with copper under the action of a catalyst to effectively modify the copper on the chamber wall and form removable byproducts. The flow rate ratio not only achieves the best reaction effect but also saves gas, thereby ensuring stable modification, effectively reducing chamber contamination, stabilizing the chamber environment, and assisting in the ignition of the dry cleaning step.

[0067] (6) Dry cleaning step: The modification efficiency is further promoted by adding power ignition. The process parameters include, but are not limited to: the upper electrode power range is 200W~600W. If the upper electrode power is too high, it will lead to excessive plasma, the reaction will be too fast, and the coating will be consumed too quickly. If the upper electrode power is too low, the amount of copper particles attached each time will be small, resulting in insufficient cleaning. Therefore, in order to ensure that the cleaning is appropriate and does not over-react, the preferred power in this embodiment is 400W and the lower electrode power is 0. The chamber pressure is 6mTorr~20mTorr to ensure the stability of the modification and the discharge of by-products. The preferred pressure in this embodiment is 10mTorr. In addition, the process gases and their flow rates are as follows: the flow rate of argon is 100sccm, the flow rate of nitrogen is 0, the flow rate of hydrogen is 0, the flow rate of ammonia is 0, the flow rate of ammonium fluoride is 10sccm, the flow rate of hydrogen peroxide is 40sccm, and the flow rate of ethanol is 5sccm. It should be noted that the flow rate of argon gas ranges from 60 sccm to 300 sccm, and it is used to assist in the ignition of ammonium fluoride, hydrogen peroxide, and ethanol, which are difficult to ignite. In addition, the mixed gas composed of ammonium fluoride, hydrogen peroxide, and ethanol modifies copper under the catalysis of the TiO2-CeO2-ZnO composite coating. The gas fluctuation is ±10%, which reduces copper particles on the sidewall of the chamber and further avoids chamber contamination.

[0068] Therefore, through the above steps, copper can be etched directly without modifying it with chlorine gas. This not only achieves plasma etching of copper but also avoids contaminating the process chamber and improves process stability. Furthermore, after etching, the preset substrate is transferred out and a dummy wafer is introduced. A mixture of hydrogen and nitrogen is used to purge the dummy wafer, removing residual gases. The hydrogenation effect of the hydrogen causes some copper particles adhering to the chamber wall to detach. After purging for 10-60 seconds, the dummy wafer is finally transferred out, thus avoiding chamber contamination.

[0069] Example 3 This invention also provides a semiconductor process apparatus, including a process chamber and a controller; wherein the controller is used to etch a copper layer of a preset substrate in the process chamber using the method described above.

[0070] Among them, process chambers such as Figure 3 As shown, the cavity interior features a three-dimensional cylindrical design, i.e., a ceramic cylinder, with an outer layer of 3-5 turns of three-dimensional coil, which reduces the impact of copper coverage on the cavity's RF power feed. Furthermore, as... Figure 4As shown, a TiO2-CeO2-ZnO composite coating with a thickness of 200-500 nm is deposited on the ceramic cylinder. It employs a porous structure with pore sizes of 5-15 nm and depths of 100-300 nm to ensure the underlying ceramic layer is not exposed. The porosity is 40%-60%, which increases the contact area. In practical applications, this composite coating serves two purposes: firstly, the Ti, Ce, and Zn oxide ceramics adhere well to the inner wall of the ceramic cylinder, providing good resistance to corrosion from argon, nitrogen, hydrogen, and NH particles; secondly, this coating acts as a catalyst layer to remove residual copper particles during the dry cleaning process.

[0071] Furthermore, for plasma direct etching of copper, the temperature of the chamber wall in the post-etching dry cleaning step needs to be maintained at a certain high temperature, such as... Figure 5 As shown, the temperature can be controlled by a thermocouple or hot air control module to maintain the chamber wall temperature at 60°C to 70°C. A mixed gas consisting of argon, hydrogen peroxide, ammonium fluoride, and ethanol is introduced in a ratio of (16~30):8:2:1, with a total flow rate of 100 sccm to 400 sccm. The chamber pressure is controlled at 6 mTorr to 20 mTorr. Simultaneously, the upper electrode power is 200W to 400W for ignition to generate free radicals that contact the composite coating. At this point, the gas forms coordination complexes with the remaining attached copper particles, transforming into... Volatile complexes are removed by the molecular pump, thereby reducing chamber contamination and improving the stability of the copper etching process.

[0072] The semiconductor process apparatus provided in this embodiment of the invention has the same technical features as the plasma etching copper method provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0073] This embodiment also provides a computer-readable storage medium storing a computer program, which is executed by a processor to perform the above-described plasma etching copper method.

[0074] The computer program product of the plasma etching copper method and semiconductor process equipment provided in the embodiments of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0075] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0076] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0077] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0078] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0079] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for plasma etching of copper, characterized in that, The method of providing a preset substrate includes: Modification step: The copper layer of the preset substrate is modified using a first process gas to modify the surface of the copper layer into cuprous chloride; First etching step: The second process gas reacts with the cuprous chloride to generate cuprous nitride, which is then used to etch the copper layer; Desorption step: After the copper layer is etched, a third process gas is used to desorb the preset substrate.

2. The method according to claim 1, characterized in that, The first process gas includes a first modified gas; wherein the first modified gas is a gas containing chlorine.

3. The method according to claim 2, characterized in that, The first process gas further includes a first dilution gas; wherein the flow rate ratio of the first modified gas and the first dilution gas is less than 1.

4. The method according to claim 1, characterized in that, The second process gas includes an etching gas and a reducing gas; wherein the etching gas is nitrogen and the reducing gas is a nitrogen-containing gas.

5. The method according to claim 4, characterized in that, The second process gas further includes a second dilution gas; wherein, in the second process gas, the flow rate of the second dilution gas is higher than the flow rate of the etching gas and the flow rate of the reducing gas.

6. The method according to claim 1, characterized in that, The modification step and the first etching step are alternated in a cycle.

7. The method according to claim 1, characterized in that, Prior to the modification step, the method further includes: First ignition step: Ignition is initiated using a fourth process gas; wherein the fourth process gas includes a second modified gas and a third dilution gas, and the flow rate ratio of the second modified gas and the third dilution gas is less than 1.

8. A method for plasma etching of copper, characterized in that, The method of providing a preset substrate includes: Second ignition step: Ignition is initiated using the fifth process gas; Second etching step: The copper layer of the preset substrate is etched using the sixth process gas; Cleaning stage: The process chamber is cleaned using the seventh process gas.

9. A semiconductor process apparatus, characterized in that, It includes a process chamber and a controller; wherein the controller is used to etch a copper layer of a preset substrate in the process chamber using the method described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, performs the steps of the method described in any one of claims 1-8.

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