Cleaning method of carbon-containing and / or nitrogen-containing silicon compound for polished section

Abstract

The invention relates to a cleaning method of a carbon-containing and / or nitrogen-containing silicon compound for a polished section. The cleaning method comprises the following steps: forming a carbon-containing and / or nitrogen-containing silicon compound film on the polished section; performing dry etching by using a fluorine-containing etching gas and an oxygen-containing etching gas; and carrying out at least one round of wet etching. The cleaning effect can be improved, and the consumption cost of the polished section is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a method for cleaning carbon-containing and / or nitrogen-containing silicon compounds used for optical slices. Background Art

[0002] During the semiconductor manufacturing process, the monitoring of process quality is very important. The daily monitoring of process quality is mainly manifested in that after the process film is deposited on the optical wafer to test the relevant parameters, the film deposited on the optical wafer is cleaned for the next process monitoring. Whether the film can be completely removed during the cleaning process, and the number of particles of different sizes on the optical wafer after cleaning, directly affect the number of times the optical wafer is used in the process of process quality monitoring, and thus affect the process cost and the degree of negative impact of the optical wafer on process quality monitoring.

[0003] However, in the prior art, for silicon compounds containing carbon and / or nitrogen, the cleaning effect is poor, resulting in high optical wafer consumption costs. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a method for cleaning carbon-containing and / or nitrogen-containing silicon compounds used for optical slices, which can improve the cleaning effect and reduce the optical slice consumption cost.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a method for cleaning carbon-containing and / or nitrogen-containing silicon compounds for optical slices, characterized in that the method is used for optical slices, including: forming a carbon-containing and / or nitrogen-containing silicon compound film on the optical slice; performing dry etching using fluorine-containing etching gas and oxygen-containing etching gas; and performing at least one round of wet etching.

[0006] Optionally, the carbon- and / or nitrogen-containing silicon compound film is selected from: a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, a carbon-nitrogen-containing silicon oxide film, and a carbon-containing silicon nitride film.

[0007] Optionally, dry etching is performed using a fluorine-containing etching gas and an oxygen-containing etching gas, including: performing the dry etching using a plasma etching process; wherein the plasma etching gas used in the plasma etching process includes fluorine plasma and oxygen plasma.

[0008] Optionally, the plasma etching process includes multiple reaction stages; wherein a reaction pressure used in an earlier part of the reaction stages is greater than a reaction pressure used in another later part of the reaction stages.

[0009] Optionally, the plasma etching process includes multiple reaction stages; wherein the high-frequency radio frequency power used in an earlier part of the reaction stages is smaller than the high-frequency radio frequency power used in another later part of the reaction stages.

[0010] Optionally, the oxygen plasma is formed by inputting oxygen; the flow rate of oxygen input in an earlier reaction stage is smaller than the flow rate of oxygen input in another later reaction stage.

[0011] Optionally, the wet etching includes: hydrofluoric acid etching and cleaning with a cleaning solution; wherein the cleaning solution is selected from one or more of the following: a mixed solution of ozone and deionized water, SC1, and HF.

[0012] Optionally, the number of rounds of wet etching is a single round; performing at least one round of wet etching includes: etching with hydrofluoric acid having a concentration of 45% to 50%, and then cleaning with hydrofluoric acid having a concentration of 0.5% to 2%.

[0013] Optionally, the number of rounds of wet etching is a single round; performing at least one round of wet etching includes: etching with hydrofluoric acid having a concentration of 45% to 50%, and then cleaning with SC1 cleaning solution.

[0014] Optionally, the method further comprises: cleaning with a mixed solution of ozone and deionized water.

[0015] Optionally, the number of rounds of wet etching is two; the first round of wet etching includes the following steps: etching with hydrofluoric acid at a concentration of 45% to 50%, and then cleaning with 0.5% to 2% hydrofluoric acid; the second round of wet etching includes the following steps: wet etching with hydrofluoric acid at a concentration of 45% to 50%, and then cleaning with SC1 cleaning solution.

[0016] Optionally, the number of rounds of wet etching is two; the first round of wet etching includes the following steps: wet etching with hydrofluoric acid at a concentration of 45% to 50%, and then cleaning with SC1 cleaning solution; the second round of wet etching includes the following steps: wet etching with hydrofluoric acid at a concentration of 45% to 50%, and then cleaning with 0.5% to 2% hydrofluoric acid.

[0017] Optionally, the method further includes at least one cleaning process using a mixed solution of ozone and deionized water for cleaning.

[0018] Optionally, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is single; wherein the cleaning process using a mixed solution of ozone and deionized water for cleaning is performed after cleaning with 0.5% to 2% hydrofluoric acid.

[0019] Optionally, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is single; wherein the cleaning process using a mixed solution of ozone and deionized water for cleaning is performed after completing two rounds of wet etching.

[0020] Optionally, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is two; wherein the cleaning process using a mixed solution of ozone and deionized water for cleaning is performed after the first round of wet etching and after the second round of wet etching, respectively.

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

[0022] In an embodiment of the present invention, after a carbon- and / or nitrogen-containing silicon compound film is formed on the optical slice, before at least one round of wet etching is performed, dry etching is first performed using a fluorine-containing etching gas and an oxygen-containing etching gas. The fluorine-containing etching gas can be used to remove the silicon component in the silicon oxide film containing nitrogen or carbon and nitrogen elements, so that silicon tetrafluoride gas and other fluorine silicon groups are formed, thereby achieving the purpose of removing the silicon component in the silicon oxide film containing nitrogen or carbon and nitrogen elements. The oxygen-containing etching gas can also be used to remove the carbon and nitrogen components in the silicon oxide film containing nitrogen or carbon and nitrogen elements, and the film to be cleaned is stripped in the form of carbon oxide groups / nitrogen oxide groups. Compared with the prior art that uses multiple rounds of wet etching to clean the film and the particulate matter brought by cleaning the film respectively, the above scheme can be used to reduce the damage to the optical slice in the process of removing the film by dry etching, and reduce the number of particulate matter brought by wet etching, thereby further reducing the damage to the optical slice in the subsequent process of removing particulate matter.

[0023] Furthermore, a plasma etching process is used to perform dry etching on the carbon-containing and / or nitrogen-containing silicon compound film; wherein the plasma etching gas used in the plasma etching process includes fluorine plasma and oxygen plasma. Compared with ordinary device wafers, it is necessary to etch the unprotected area of ​​the photoresist on the basis of forming the photoresist. The technical solution of the embodiment of the present invention is performed on the photoresist, and the plasma etching process can use the characteristics of using gas and plasma energy to react, and can be removed quickly and safely.

[0024] Furthermore, the plasma etching process includes multiple reaction stages; wherein the reaction pressure used in the first reaction stage is greater than the reaction pressure used in the second reaction stage. By adopting the above scheme, the reaction speed can be increased by a larger reaction pressure in the first reaction stage. Since the number of gas molecules is large and the molecular free path is small, more reactions occur on the surface of the film, and more elements on the surface of the film are removed than inside the film. Then, by reducing the reaction pressure, the number of gas molecules can be reduced in the second reaction stage, the molecular free path is increased, and more elements react with the components inside the film to remove the elements inside the film. Thus, by adopting a larger reaction pressure in the first stage and a smaller reaction pressure in the second stage, a better balance can be achieved between removal efficiency and protection of the optical film.

[0025] Furthermore, the plasma etching process includes multiple reaction stages; wherein the high-frequency radio frequency power used in the first reaction stage is less than the high-frequency radio frequency power used in the second reaction stage. The above scheme is adopted to achieve a situation in which, in the first reaction stage, a smaller high-frequency radio frequency power is used to achieve a smaller number of dissociated gases and a smaller number of atomic groups participating in the reaction in the cavity. At this time, more reactions occur on the surface of the film, and more elements on the surface of the film are removed than inside the film. Then, by increasing the high-frequency radio frequency power, it can be achieved in the second reaction stage that the number of dissociated gases increases, the number of atomic groups participating in the reaction in the cavity increases, and more react with the components inside the film to remove the elements inside the film. Thus, by adopting a smaller high-frequency radio frequency power in the early stage and a larger high-frequency radio frequency power in the later stage, a better balance can be achieved between removal efficiency and protection of the optical sheet.

[0026] Furthermore, the oxygen flow rate input in the first part of the reaction stage is smaller than the oxygen flow rate input in the second part of the reaction stage. By adopting the above scheme, in the first part of the reaction stage, by adopting a smaller oxygen flow rate, the reaction rate can be controlled to be lower, and the areas on the optical sheet not covered by carbon-containing and / or nitrogen-containing silicon compounds can be protected. Then, by increasing the oxygen flow rate, the reaction rate can be increased in the second part of the reaction stage, and more reactions can be carried out with the components inside the film to remove the elements inside the film. At this time, the intermediate products obtained by the existing reactions can be evenly formed on the entire optical sheet, and the optical sheet can also be protected to a certain extent. Therefore, by adopting a smaller oxygen flow rate in the early stage and a larger oxygen flow rate in the later stage, a better balance can be achieved between removal efficiency and protection of the optical sheet.

[0027] Furthermore, the method also includes at least one cleaning process using a mixed solution of ozone and deionized water for cleaning. Since existing cleaning equipment often has multiple cleaning liquid input pipelines and can select appropriate cleaning liquids according to actual needs, by setting the first cleaning liquid in the same equipment to be dilute hydrofluoric acid and the second cleaning liquid to be a mixed solution of ozone and deionized water, double cleaning can be achieved without increasing additional production costs, further improving the cleaning effect. Furthermore, by performing a mixed solution of ozone and deionized water cleaning later, particulate matter can be better reduced.

[0028] Furthermore, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is two, which can further reduce particulate matter. Specifically, when the original thickness is greater than the preset thickness (at this time, even if the mixed solution of ozone and deionized water is added for cleaning, the surface of the optical sheet will not be damaged) or the requirement for residual film thickness is small (such as being able to accept a certain degree of damage to the surface of the optical sheet due to insufficient residual film thickness), and the requirement for particulate matter control is high (such as requiring the number of remaining particulate matter after cleaning to be less than or equal to the preset number), two steps of cleaning using a mixed solution of ozone and deionized water can be added to reduce particulate matter to a greater extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic flow chart of a method for cleaning a carbon-containing and / or nitrogen-containing silicon compound used for an optical sheet according to an embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of reaction parameters of multiple reaction stages included in a plasma etching process in an embodiment of the present invention;

[0031] Figure 3 is a schematic flow chart of a first wet etching method in an embodiment of the present invention;

[0032] Figure 4 is a schematic flow chart of a second wet etching method in an embodiment of the present invention;

[0033] Figure 5 is a schematic flow chart of a third wet etching method in an embodiment of the present invention;

[0034] Figure 6 It is a schematic flow chart of the fourth wet etching method in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In existing manufacturing technologies, the cleaning effect of carbon- and / or nitrogen-containing silicon compounds is poor, resulting in high optical wafer consumption costs.

[0036] Specifically, the cleaning method for carbon-containing and / or nitrogen-containing silicon compounds currently commonly used in the manufacturing process is repeated wet etching. Since the carbon-containing and / or nitrogen-containing silicon compounds deposited on the silicon wafer cannot be completely cleaned after wet etching, in a specific application method, the method of increasing the number of cleaning times can be used to achieve the purpose of cleaning the film.

[0037] Research has found that although most of the carbon- and / or nitrogen-containing silicon compounds deposited on the silicon wafer can be removed after multiple wet etchings, there may be too many particles that exceed the control range, affecting the reusability of the wafer and increasing consumption costs.

[0038] In one solution, a cleaning solution for removing particles can be used to re-clean the optical slice through multiple wet etching cleanings to remove particles on the surface of the optical slice. Excessive rounds of wet etching can easily cause serious damage to the optical slice.

[0039] In an embodiment of the present invention, after a carbon- and / or nitrogen-containing silicon compound film is formed on the optical slice, before at least one round of wet etching is performed, dry etching is first performed using a fluorine-containing etching gas and an oxygen-containing etching gas. The fluorine-containing etching gas can be used to remove the silicon component in the silicon oxide film containing nitrogen or carbon and nitrogen elements, so that silicon tetrafluoride gas and other fluorine silicon groups are formed, thereby achieving the purpose of removing the silicon component in the silicon oxide film containing nitrogen or carbon and nitrogen elements. The oxygen-containing etching gas can also be used to remove the carbon and nitrogen components in the silicon oxide film containing nitrogen or carbon and nitrogen elements, and the film to be cleaned is stripped in the form of carbon oxide groups / nitrogen oxide groups. Compared with the prior art that uses multiple rounds of wet etching to clean the film and the particulate matter brought by cleaning the film respectively, the above scheme can be used to reduce the damage to the optical slice in the process of removing the film by dry etching, and reduce the number of particulate matter brought by wet etching, thereby further reducing the damage to the optical slice in the subsequent process of removing particulate matter.

[0040] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] Reference Figure 1 , Figure 1 The present invention is a schematic flow chart of a method for cleaning a carbon-containing and / or nitrogen-containing silicon compound for optical wafers according to an embodiment of the present invention. The cleaning method can be used for optical wafers and can also include steps S11 to S13:

[0042] Step S11: forming a carbon- and / or nitrogen-containing silicon compound film on the optical sheet;

[0043] Step S12: performing dry etching using a fluorine-containing etching gas and an oxygen-containing etching gas;

[0044] Step S13: performing at least one round of wet etching.

[0045] In step S11 , the optical wafer may be a wafer optical wafer on which no pattern has been formed, and may be used as a monitor wafer in many processes.

[0046] Furthermore, the material of the optical sheet may be silicon.

[0047] Specifically, the optical wafer may be a silicon wafer, or a substrate on which an epitaxial layer (Epitaxy layer, Epilayer) is grown.

[0048] In the embodiment of the present invention, by setting the material of the optical slice to be silicon, a carbon- and / or nitrogen-containing silicon compound can be formed based on the optical slice material, thereby reducing the cost of generating the film to be cleaned. Furthermore, the film to be cleaned is a carbon- and / or nitrogen-containing silicon compound film, and the damage to the silicon slice during the cleaning process will be greater than the damage to the optical slice of other materials. By cleaning the carbon- and / or nitrogen-containing silicon compound film on the silicon slice, the cleaning effect and damage condition can be more effectively determined.

[0049] Further, the silicon compound film containing carbon and / or nitrogen may be selected from: a silicon oxide film containing carbon, a silicon oxide film containing nitrogen, a silicon oxide film containing carbon and nitrogen, and a silicon nitride film containing carbon.

[0050] Among them, the carbon-containing silicon oxide film may include silicon oxide carbide (SiCO), for example, which can be used as a nitrogen-free dielectric anti-reflective coating (NFDARC); the nitrogen-containing silicon oxide film may include silicon oxynitride (SiON), for example, which can be used as a dielectric anti-reflective coating (DARC). The above two materials can effectively improve reflection, standing wave and other problems.

[0051] The silicon oxide film containing carbon and nitrogen and the silicon nitride film containing carbon may include, for example, silicon carbon nitride (SiCN), and may be used to prevent a metal diffusion layer or an etch stop layer.

[0052] Furthermore, a carbon- and / or nitrogen-containing silicon compound film may be formed by a chemical vapor deposition process, and an ion implantation process may be used to form a carbon- and / or nitrogen-containing silicon compound film.

[0053] When silicon is used as the material of the optical sheet, a chemical vapor deposition process can be used to input carbon-containing and / or nitrogen-containing reaction raw materials to react with the optical sheet to obtain a carbon-containing and / or nitrogen-containing silicon compound film; ion implantation can also be performed into the optical sheet to obtain a carbon-containing and / or nitrogen-containing silicon compound film. In the embodiment of the present invention, the specific formation method of the carbon-containing and / or nitrogen-containing silicon compound film is not limited.

[0054] In step S12, the step of performing dry etching using a fluorine-containing etching gas and an oxygen-containing etching gas may include: performing the dry etching using a plasma etching process; wherein the plasma etching gas used in the plasma etching process includes fluorine plasma and oxygen plasma.

[0055] In an embodiment of the present invention, a plasma etching process is used to perform dry etching on the carbon-containing and / or nitrogen-containing silicon compound film; wherein the plasma etching gas used in the plasma etching process includes fluorine plasma and oxygen plasma. Compared with ordinary device wafers, it is necessary to etch the unprotected area of ​​the photoresist on the basis of forming the photoresist. The technical solution of the embodiment of the present invention is performed on the optical wafer, and the plasma etching process can use the characteristics of using gas and plasma energy to react, and remove quickly and safely.

[0056] It should be pointed out that the above-mentioned plasma etching process can utilize high-energy ion beam bombardment to remove the thin film. In an embodiment of the present invention, a dry etching process other than the plasma etching process can also be used for etching. For example, fluorine-containing etching gas and oxygen-containing etching gas can be input into the etching chamber, and chemical reactions are activated in this atmosphere to remove the thin film. In comparison, the plasma etching process has a faster reaction speed and can improve the etching efficiency.

[0057] Furthermore, the plasma etching process may include multiple reaction stages; each reaction stage may have its own reaction parameters.

[0058] Reference Figure 2 , Figure 2 It is a schematic diagram of reaction parameters of multiple reaction stages included in a plasma etching process in an embodiment of the present invention.

[0059] exist Figure 2 In the figure, three reaction stages are taken as an example to illustrate. The first reaction stage can have a reaction pressure p1, a high-frequency radio frequency power P1 and an oxygen flow rate Q1, the second reaction stage can have a reaction pressure p2, a high-frequency radio frequency power P2 and an oxygen flow rate Q2, and the third reaction stage can have a reaction pressure p3, a high-frequency radio frequency power P3 and an oxygen flow rate Q3.

[0060] Specifically, the reaction parameters of adjacent reaction stages may be the same or different.

[0061] In a specific implementation, the reaction pressure used in an earlier reaction stage may be greater than the reaction pressure used in another later reaction stage.

[0062] Specifically, it may be p1>p2>p3, or it may be p1=p2>p3, or it may be p1>p2=p3.

[0063] By adopting the above scheme, it is possible to increase the reaction speed in the first part of the reaction stage by using a larger reaction pressure. Since the number of gas molecules is large and the molecular free path becomes smaller, more reactions occur on the surface of the film, and more elements are removed from the surface of the film than from the inside of the film.

[0064] Specifically, a reaction pressure of the order of hundreds of mTorr, for example, 100 mTorr to 200 mTorr, may be used to remove more elements on the surface of the film, such as carbon, nitrogen, silicon, etc. on the surface of the film.

[0065] Furthermore, by lowering the reaction pressure, it can be achieved that in the latter part of the reaction stage, the number of gas molecules is reduced, the molecular free path is increased, and more molecules react with the components inside the film to remove the elements inside the film.

[0066] Specifically, a reaction pressure of ten mTorr level, such as 10 mTorr to 90 mTorr, may be used to remove more elements inside the film, such as carbon, nitrogen, silicon, etc. inside the film.

[0067] It should be particularly pointed out that since the embodiment of the present invention is applied to an optical sheet and no pattern has been formed yet, there are no grooves or height differences. The entire optical sheet has a uniform thin film surface area and a thin film internal area. By adopting a larger reaction pressure in the early stage and a smaller reaction pressure in the later stage, it can be achieved that only the components on the surface of the thin film are reacted on the full optical sheet in the early stage, and the intermediate products obtained by the reaction can be uniformly formed on the full optical sheet, and then uniformly react with the components in the lower layer of the thin film on the full optical sheet. The density and distribution of the above intermediate products will not affect the later process, thereby improving the uniformity of removal and reducing the damage caused by dry etching.

[0068] In the embodiment of the present invention, by adopting a reaction pressure that is larger in the early stage and smaller in the later stage, a better balance can be achieved between the removal efficiency and the protection of the optical sheet.

[0069] In a specific implementation, the high-frequency radio frequency power used in an earlier reaction stage is smaller than the high-frequency radio frequency power used in another later reaction stage.

[0070] Specifically, it may be P1<P2<P3, or P1=P2<P3, or P1<P2=P3.

[0071] By adopting the above scheme, it is possible to achieve a situation in which, in the first part of the reaction stage, the number of dissociated gases is smaller and the number of atomic groups participating in the reaction in the cavity is smaller through a smaller high-frequency RF power. At this time, more reactions occur on the surface of the film, and more elements on the surface of the film are removed compared to the inside of the film.

[0072] Specifically, a reduced high-frequency radio frequency power, such as 100 W to 200 W, can be used to remove more elements on the surface of the film, such as carbon, nitrogen, silicon, etc. on the surface of the film.

[0073] Furthermore, by increasing the high-frequency RF power, it is possible to achieve in the latter part of the reaction stage that the number of dissociated gases increases, the number of atomic groups participating in the reaction in the cavity increases, and more react with the components inside the film to remove the elements inside the film.

[0074] Specifically, doubled high-frequency radio frequency power, for example, 400 W to 600 W, can be used to remove more elements inside the film, such as carbon, nitrogen, silicon, etc. inside the film.

[0075] It should be particularly pointed out that since the embodiment of the present invention is applied to an optical sheet and no pattern has been formed yet, there are no grooves or high and low level differences. The entire optical sheet has a uniform thin film surface area and a thin film internal area. By adopting a high-frequency RF power that is smaller in the early stage and larger in the later stage, it can be achieved that only the components on the surface of the thin film on the all-optical sheet are reacted in the early stage, and the intermediate products obtained by the reaction can be uniformly formed on the all-optical sheet, and then react uniformly with the components in the lower layer of the thin film on the all-optical sheet. The density and distribution of the above intermediate products will not affect the later process, thereby improving the uniformity of removal and reducing the damage caused by dry etching.

[0076] In the embodiment of the present invention, by adopting a high-frequency radio frequency power that is smaller in the early stage and larger in the later stage, a better balance can be achieved between the removal efficiency and the protection of the optical sheet.

[0077] In a specific implementation, the oxygen plasma is formed by inputting oxygen; the flow rate of oxygen input in an earlier reaction stage may be smaller than the flow rate of oxygen input in another later reaction stage.

[0078] Specifically, it may be Q1<Q2<Q3, or it may be Q1=Q2<Q3, or it may be Q1<Q2=Q3.

[0079] By adopting the above scheme, in the first part of the reaction stage, by adopting a smaller oxygen flow rate, the reaction speed can be controlled to be lower, and the areas on the optical wafer that are not covered by the carbon-containing and / or nitrogen-containing silicon compounds can be protected.

[0080] Specifically, an oxygen flow rate of the order of 100 sccm, such as 100 sccm to 300 sccm, can be used, which can not only control the reaction rate to be lower, but also remove more elements on the surface of the film.

[0081] Furthermore, by increasing the oxygen flow rate, the reaction speed can be increased in the later reaction stage, and more reactions can be carried out with the components inside the film to remove the elements inside the film. At this time, the intermediate products obtained by the reaction can be evenly formed on the full optical sheet, and the optical sheet can also be protected to a certain extent.

[0082] Specifically, an oxygen flow rate of ten sccm level, such as 20 sccm to 90 sccm, can be used, which can not only increase the reaction speed but also remove more elements inside the film.

[0083] In the embodiment of the present invention, by adopting an oxygen flow rate that is smaller in the early stage and larger in the later stage, a better balance can be achieved between the removal efficiency and the protection of the optical sheet.

[0084] Furthermore, in multiple reaction stages, the reaction pressure and the high-frequency radio frequency power are adjusted asynchronously, and the oxygen flow rate is adjusted after the reaction pressure and the high-frequency radio frequency power have been adjusted at least once.

[0085] In an embodiment of the present invention, by first adjusting the reaction pressure and the high-frequency RF power and then adjusting the oxygen flow rate, a smaller oxygen flow rate can be used in both the reaction pressure adjustment and high-frequency RF power adjustment stages, thereby better protecting the optical sheet.

[0086] In a first specific embodiment, the plasma etching process may include four reaction stages, the first reaction stage may have a reaction pressure p1, a high-frequency RF power P1 and an oxygen flow rate Q1, the second reaction stage may have a reaction pressure p2, a high-frequency RF power P2 and an oxygen flow rate Q2, the third reaction stage may have a reaction pressure p3, a high-frequency RF power P3 and an oxygen flow rate Q3, and the fourth reaction stage may have a reaction pressure p4, a high-frequency RF power P4 and an oxygen flow rate Q4.

[0087] Among them, p1>p2=p3=p4, P1=P2<P3=P4, Q1=Q2=Q3<Q4.

[0088] Specifically, only p1 can be adjusted between the first reaction stage and the second reaction stage without adjusting P1, and P2 can be adjusted between the second reaction stage and the third reaction stage. At this time, since both the reaction pressure and the high-frequency RF power are adjusted, the oxygen flow rate Q3 can be adjusted between the third reaction stage and the fourth reaction stage.

[0089] In the embodiment of the present invention, by first adjusting the reaction pressure, then adjusting the high-frequency RF power, and finally adjusting the oxygen flow rate, a smaller oxygen flow rate can be used in both the reaction pressure adjustment and high-frequency RF power adjustment stages, thereby better protecting the optical slice. Furthermore, since the adjustment step size of the reaction pressure is relatively large (adjusted from the hundred mTorr level to the ten mTorr level), the adjustment step size of the high-frequency RF power is relatively small (doubled adjustment), adjusting the reaction pressure first and then adjusting the high-frequency RF power helps to improve the process adjustment efficiency.

[0090] It can be understood that in the embodiment of the present invention, the number of adjustments is not limited, for example, it can be p1>p2=p3>p4.

[0091] It should be pointed out that in the second specific implementation, p1=p2>p3=p4, P1<P2=P3=P4, Q1=Q2=Q3<Q4 can also be set, and a smaller oxygen flow rate can be used in both the reaction pressure adjustment and high-frequency RF power adjustment stages, thereby achieving the effect of better protecting the optical sheet.

[0092] In an embodiment of the present invention, other corresponding process parameters may also be set: the gas flow rate of silicon tetrafluoride is in the range of 70 sccm to 200 sccm, the low-frequency RF power is in the range of 30 W to 300 W, and the reaction time of dry etching is in the range of 10 s to 120 s.

[0093] Furthermore, the wet etching may include: hydrofluoric acid etching and cleaning with a cleaning solution; wherein the cleaning solution is selected from one or more of the following: a mixed solution of ozone and deionized water, SC1, and HF.

[0094] In the embodiment of the present invention, by selecting appropriate etchants and cleaning solutions, effective supplementation to dry etching can be achieved, and on the basis of dry etching, the cleaning effectiveness of carbon-containing and / or nitrogen-containing silicon compounds on the optical wafer can be further improved.

[0095] Reference Figure 3 , Figure 3 1 is a schematic flow chart of a first wet etching method in an embodiment of the present invention. The first wet etching method may include step S31 and may also include step S32.

[0096] In step S31, etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then cleaning is performed using hydrofluoric acid with a concentration of 0.5% to 2%.

[0097] Among them, hydrofluoric acid with a concentration of 45% to 50% is concentrated hydrofluoric acid. Taking a concentrated hydrofluoric acid stock solution as an example, the concentration is 49%.

[0098] Hydrofluoric acid with a concentration of 0.5% to 2% is dilute hydrofluoric acid, which can be obtained by diluting concentrated hydrofluoric acid at a ratio of 1:100, for example.

[0099] Furthermore, the duration of etching using hydrofluoric acid with a concentration of 45% to 50% may be longer than the duration of cleaning using hydrofluoric acid with a concentration of 0.5% to 2%.

[0100] In a specific implementation, based on dry etching, the substrate is first cleaned with a 49% concentration hydrofluoric acid stock solution for 60 seconds, and then cleaned with a 1:100 concentration dilute hydrofluoric acid solution for 10 to 15 seconds.

[0101] In an embodiment of the present invention, by using concentrated hydrofluoric acid for etching and then using dilute hydrofluoric acid for cleaning, wet etching can be used for secondary etching on the basis of dry etching to improve the etching effect, and then the cleaning effect can be further improved by cleaning with a dilute hydrofluoric acid solution.

[0102] In step S32, a mixed solution of ozone and deionized water is used for cleaning.

[0103] The concentration of ozone in the mixed solution of ozone and deionized water can be selected from 5 ppm to 80 ppm.

[0104] The cleaning time can be selected according to the specific situation. For example, when the degree of wet etching is severe, in order to reduce damage to the optical slice, a shorter cleaning time can be used. Correspondingly, when the degree of wet etching is light, in order to improve the cleaning effect, a longer cleaning time can be used.

[0105] In a specific implementation of the embodiment of the present invention, the cleaning time of the mixed solution of ozone and deionized water can be selected from: 10s to 300s.

[0106] The method also includes at least one cleaning process using a mixed solution of ozone and deionized water for cleaning. Since existing cleaning equipment often has multiple cleaning liquid input pipelines and can select appropriate cleaning liquids according to actual needs, by setting the first cleaning liquid in the same equipment to be dilute hydrofluoric acid and the second cleaning liquid to be a mixed solution of ozone and deionized water, double cleaning can be achieved without increasing additional production costs, further improving the cleaning effect. Furthermore, by performing a mixed solution of ozone and deionized water cleaning later, particulate matter can be better reduced.

[0107] Furthermore, before using a mixed solution of ozone and deionized water for cleaning (i.e., step S32), the step of determining whether one or more of the following is satisfied may also be included: the initial thickness of the carbon-containing and / or nitrogen-containing silicon compound film is greater than or equal to a preset thickness; the number of particles of a unit size on the optical wafer obtained after at least one round of wet etching is required to be less than or equal to a preset number.

[0108] Specifically, when the original thickness is greater than the preset thickness, even if a mixed solution of ozone and deionized water is added for cleaning, no damage will be caused to the surface of the optical sheet.

[0109] Correspondingly, when the requirement for residual film thickness is small, such as when a certain degree of damage to the surface of the optical sheet due to insufficient residual film thickness is acceptable, the cleaning effect can be further improved under acceptable conditions by adding a mixed solution of ozone and deionized water for cleaning.

[0110] In addition, when the requirements for particle control are high, such as requiring the number of remaining particles after cleaning to be less than or equal to a preset number, the cleaning effect can be further improved on the basis of sacrificing a certain degree of light sheet surface.

[0111] Reference Figure 4 , Figure 4 4 is a flow chart of a second wet etching method in an embodiment of the present invention. The second wet etching method may include step S41 and may also include step S42.

[0112] In step S41, etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then cleaning is performed using SC1 cleaning solution.

[0113] Among them, hydrofluoric acid with a concentration of 45% to 50% is concentrated hydrofluoric acid. Taking a concentrated hydrofluoric acid stock solution as an example, the concentration is 49%.

[0114] The ratio of each component in the SC1 cleaning solution may be NH3H2O:H2O2:H2O=1:1-4:50-200.

[0115] The ratio may be a volume ratio of each component. In a specific embodiment of the present invention, NH3H2O:H2O2:H2O=1:2:50 may be set.

[0116] Furthermore, the time for etching using hydrofluoric acid with a concentration of 45% to 50% may be shorter than the time for cleaning using SC1 cleaning solution.

[0117] In a specific implementation, on the basis of dry etching, the surface is first cleaned with a 49% concentration hydrofluoric acid stock solution for 60 seconds, and then cleaned with a 1:2:50 NH3H2O:H2O2:H2O mixed solution for 300 seconds.

[0118] In the embodiment of the present invention, concentrated hydrofluoric acid is used for etching and then SC1 cleaning solution is used for cleaning. On the basis of dry etching, wet etching can be used for secondary etching to improve the etching effect, and then the cleaning effect can be further improved by cleaning with SC1 cleaning solution.

[0119] In step S42, a mixed solution of ozone and deionized water is used for cleaning.

[0120] For more information about step S42, please refer to the above text and the description of step S32, which will not be repeated here.

[0121] In the embodiment of the present invention, on the basis of the secondary etching by dry etching and wet etching, a mixed solution of ozone and deionized water may be used for cleaning to further improve the cleaning effect.

[0122] Reference Figure 5 , Figure 5 It is a schematic flow chart of the third wet etching method in an embodiment of the present invention.

[0123] In a specific implementation of the embodiment of the present invention, the third wet etching method may only include step S51 and step S53, that is, the step of using a mixed solution of ozone and deionized water for cleaning is not included.

[0124] In step S51 , etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then cleaning is performed using hydrofluoric acid with a concentration of 0.5% to 2%.

[0125] Among them, due to the use of two wet etching steps, Figure 3 Compared with step S31 shown in the figure, the etching time can be shorter and the cleaning time can be shorter.

[0126] In a specific implementation, the surface of the substrate may be first cleaned with a 49% hydrofluoric acid stock solution for 30 seconds, and then cleaned with a 0.5% to 2% dilute hydrofluoric acid solution for 15 seconds.

[0127] For more details about step S51, please refer to the above text and the description of step S31, which will not be repeated here.

[0128] In step S53, hydrofluoric acid with a concentration of 45% to 50% is used for wet etching, and then SC1 cleaning solution is used for cleaning.

[0129] Among them, due to the use of two wet etching steps, Figure 4 Compared with step S41 shown in the figure, the etching time can be shorter and the cleaning time can be shorter.

[0130] In one embodiment, the washing may be performed with a 49% hydrofluoric acid solution for 30 seconds, and then with a 1:2:50 NH3H2 O :H2O2:H2O mixed solution for cleaning for 200s.

[0131] For more details about step S53, please refer to the above text and the description of step S41, which will not be repeated here.

[0132] Furthermore, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning can be single; wherein the cleaning process using a mixed solution of ozone and deionized water for cleaning can be performed after cleaning using 0.5% to 2% hydrofluoric acid.

[0133] In another specific implementation of the embodiment of the present invention, the third wet etching method may only include steps S51, S52 and S53, that is, only include a single step of cleaning with a mixed solution of ozone and deionized water, and this step may be arranged after S51.

[0134] For more details about step S52, please refer to the above text and the description of step S32, which will not be repeated here.

[0135] In the embodiment of the present invention, since the existing cleaning equipment often has a variety of cleaning liquid input pipelines, and the appropriate cleaning liquid can be selected according to actual needs, by setting the first cleaning liquid in the same equipment to be dilute hydrofluoric acid and the second cleaning liquid to be a mixed solution of ozone and deionized water, it is possible to achieve double cleaning without increasing additional production costs, thereby further improving the cleaning effect. Furthermore, since the material categories of 0.5% to 2% hydrofluoric acid are relatively small, it can be input and configured on-site through the cleaning liquid input pipeline, and can also be pre-configured and input into the cleaning liquid input pipeline, which is more convenient.

[0136] In another specific implementation of the embodiment of the present invention, the third wet etching method may only include steps S51, S53 and S54, that is, only include a single step of cleaning with a mixed solution of ozone and deionized water, and this step can be arranged after two rounds of wet etching steps (ie, S52).

[0137] For more details about step S54, please refer to the above text and the description of step S32, which will not be repeated here.

[0138] In an embodiment of the present invention, the step of using a mixed solution of ozone and deionized water is placed after the two rounds of wet etching. On the basis of three etchings performed by dry etching and two rounds of wet etching, cleaning can be performed by using a mixed solution of ozone and deionized water to further improve the cleaning effect.

[0139] In another specific implementation of the embodiment of the present invention, the third wet etching method may include steps S51 to S54, that is, it includes two steps of cleaning with a mixed solution of ozone and deionized water, and can be respectively arranged after the first round of wet etching steps (i.e., S51) and after the second round of wet etching steps (i.e., S53).

[0140] In the embodiment of the present invention, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is two, which can further reduce particulate matter. Specifically, when the original thickness is greater than the preset film thickness (at this time, even if the mixed solution of ozone and deionized water is added for cleaning, the surface of the optical sheet will not be damaged) or the requirement for residual film thickness is small (such as being able to accept a certain degree of damage to the surface of the optical sheet due to insufficient residual film thickness), and the requirement for particulate matter control is high (such as requiring the number of remaining particulate matter after cleaning to be less than or equal to the preset number), two steps of cleaning using a mixed solution of ozone and deionized water can be added to reduce particulate matter to a greater extent and improve the cleaning effect.

[0141] Reference Figure 6 , Figure 6 It is a schematic flow chart of the fourth wet etching method in an embodiment of the present invention.

[0142] In a specific implementation of the embodiment of the present invention, the fourth wet etching method may only include step S61 and step S63, that is, the step of using a mixed solution of ozone and deionized water for cleaning is not included.

[0143] In step S61, hydrofluoric acid with a concentration of 45% to 50% is used for wet etching, and then SC1 cleaning solution is used for cleaning.

[0144] Among them, due to the use of two wet etching steps, Figure 4 Compared with step S41 shown in the figure, the etching time can be shorter and the cleaning time can be shorter.

[0145] In one embodiment, the washing may be performed with a 49% hydrofluoric acid solution for 30 seconds, and then with a 1:2:50 NH3H2 O :H2O2:H2O mixed solution for 300s.

[0146] For more details about step S61, please refer to the above text and the description of step S41, which will not be repeated here.

[0147] In step S63 , hydrofluoric acid with a concentration of 45% to 50% may be used for wet etching, and then 0.5% to 2% hydrofluoric acid may be used for cleaning.

[0148] Among them, due to the use of two wet etching steps, Figure 3 Compared with step S31 shown in the figure, the etching time can be shorter and the cleaning time can be shorter.

[0149] In a specific embodiment, the surface of the substrate may be first cleaned with a 49% hydrofluoric acid stock solution for 30 seconds, and then cleaned with a 0.5% to 2% dilute hydrofluoric acid solution for 10 seconds.

[0150] For more details about step S63, please refer to the above text and the description of step S31, which will not be repeated here.

[0151] It should be particularly pointed out that in the case of two wet etching steps, the same cleaning solution is used for post-etching cleaning. When used for cleaning after the first wet etching step, the cleaning time is longer than the cleaning time after the second wet etching step.

[0152] like Figure 5 and Figure 6 In a specific embodiment of the two cleaning methods shown, for the case where 0.5% to 2% hydrofluoric acid is first used for cleaning (such as step S51) and then SC1 cleaning solution is used for cleaning (such as step S53), 0.5% to 2% dilute hydrofluoric acid solution can be used for cleaning for 15s, and 1:2:50 NH3H2 O :H2O2:H2O mixed solution for 200s. In contrast, for the case where SC1 cleaning solution is first used for cleaning (such as step S61) and then 0.5% to 2% hydrofluoric acid is used (such as step S63), 1:2:50 NH3H2 O :H2O2:H2O mixed solution for 300s, and then clean with 0.5% to 2% dilute hydrofluoric acid solution for 10s.

[0153] In an embodiment of the present invention, by setting the cleaning time for cleaning after the previous wet etching to be longer than the cleaning time for cleaning after the subsequent wet etching, a better foundation can be provided for the subsequent wet etching through a longer cleaning time during the previous wet etching process.

[0154] Furthermore, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning can be single; wherein the cleaning process using a mixed solution of ozone and deionized water for cleaning can be performed after cleaning using 0.5% to 2% hydrofluoric acid.

[0155] In another specific implementation of the embodiment of the present invention, the fourth wet etching method may only include steps S61, S63 and S64, that is, only include a single step of cleaning with a mixed solution of ozone and deionized water, and this step may be arranged after S63.

[0156] For more details about step S64, please refer to the above text and the description of step S32, which will not be repeated here.

[0157] In the embodiment of the present invention, since the existing cleaning equipment often has a variety of cleaning liquid input pipelines, and the appropriate cleaning liquid can be selected according to actual needs, by setting the first cleaning liquid in the same equipment to be dilute hydrofluoric acid and the second cleaning liquid to be a mixed solution of ozone and deionized water, it is possible to achieve double cleaning without increasing additional production costs, thereby further improving the cleaning effect. Furthermore, since the material categories of 0.5% to 2% hydrofluoric acid are relatively small, it can be input and configured on-site through the cleaning liquid input pipeline, and can also be pre-configured and input into the cleaning liquid input pipeline, which is more convenient.

[0158] In addition, in an embodiment of the present invention, the step of using a mixed solution of ozone and deionized water is placed after the two rounds of wet etching steps. On the basis of three etchings performed by dry etching and two rounds of wet etching, cleaning can be performed by using a mixed solution of ozone and deionized water to further improve the cleaning effect.

[0159] In another specific implementation of the embodiment of the present invention, the fourth wet etching method may include steps S61 to S64, that is, it includes two steps of cleaning with a mixed solution of ozone and deionized water, and can be respectively arranged after the first round of wet etching steps (i.e., S61) and after the second round of wet etching steps (i.e., S63).

[0160] In the embodiment of the present invention, the number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is two, which can further reduce particulate matter. Specifically, when the original thickness is greater than the preset film thickness (at this time, even if the mixed solution of ozone and deionized water is added for cleaning, the surface of the optical sheet will not be damaged) or the requirement for residual film thickness is small (such as being able to accept a certain degree of damage to the surface of the optical sheet due to insufficient residual film thickness), and the requirement for particulate matter control is high (such as requiring the number of remaining particulate matter after cleaning to be less than or equal to the preset number), two steps of cleaning using a mixed solution of ozone and deionized water can be added to reduce particulate matter to a greater extent and improve the cleaning effect.

[0161] In a specific application of the embodiment of the present invention, Figures 3 to 6 The four cleaning methods shown were tested on multiple optical sheets. After cleaning with the first cleaning method, the residual film thickness was 5-6A, the average number of particles on the 0.5um area was within 10, and the average number of particles on the 0.12um area was 0. After cleaning with the second cleaning method, the residual film thickness was 2-3A, the average number of particles on the 0.5um area was within 100, and the average number of particles on the 0.12um area was within 3. After cleaning with the third cleaning method, the residual film thickness was 1A, the average number of particles on the 0.5um area was within 60, and the average number of particles on the 0.12um area was within 1. After cleaning with the fourth cleaning method, the residual film thickness was 2-4A, the average number of particles on the 0.5um area was within 10, and the average number of particles on the 0.12um area was within 1.

[0162] It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article indicates that the associated objects before and after are in an "or" relationship.

[0163] The "plurality" appearing in the embodiments of the present application refers to two or more.

[0164] The first, second, etc. descriptions appearing in the embodiments of the present application are only used for illustration and distinction of the description objects. There is no order, nor do they indicate any special limitation on the number of devices in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0165] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for cleaning carbon-containing and / or nitrogen-containing silicon compounds for optical sheets, characterized in that: The method is used for a light sheet, and is characterized by comprising: forming a silicon compound film containing carbon and / or nitrogen on the optical sheet; Dry etching is performed using fluorine-containing etching gas and oxygen-containing etching gas; At least one round of wet etching is performed.

2. The method according to claim 1, characterized in that The carbon- and / or nitrogen-containing silicon compound film is selected from: Silicon oxide film containing carbon, silicon oxide film containing nitrogen, silicon oxide film containing carbon and nitrogen, and silicon nitride film containing carbon.

3. The method according to claim 1, characterized in that Dry etching is performed using fluorine-containing etching gas and oxygen-containing etching gas, including: Using a plasma etching process to perform the dry etching; Wherein, the plasma etching gas used in the plasma etching process includes fluorine plasma and oxygen plasma.

4. The method according to claim 3, characterized in that The plasma etching process comprises a plurality of reaction stages; The reaction pressure used in an earlier reaction stage is greater than the reaction pressure used in another later reaction stage.

5. The method according to claim 3, characterized in that: The plasma etching process comprises a plurality of reaction stages; The high-frequency radio frequency power used in the first reaction stage is smaller than the high-frequency radio frequency power used in the second reaction stage.

6. The method according to claim 4 or 5, characterized in that: The oxygen plasma is formed by inputting oxygen; The oxygen flow rate input in the first partial reaction stage is smaller than the oxygen flow rate input in the second partial reaction stage.

7. The method according to claim 1, characterized in that The wet etching includes: hydrofluoric acid etching and cleaning with a cleaning solution; Wherein, the cleaning solution is selected from one or more of the following: Mixed solution of ozone and deionized water, SC1, HF.

8. The method according to claim 7, characterized in that The number of rounds of wet etching is a single round; The performing at least one round of wet etching comprises: The etching is performed using hydrofluoric acid having a concentration of 45% to 50%, and then the cleaning is performed using hydrofluoric acid having a concentration of 0.5% to 2%.

9. The method according to claim 7, characterized in that: The number of rounds of wet etching is a single round; The performing at least one round of wet etching comprises: The etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then the cleaning is performed using SC1 cleaning solution.

10. The method according to claim 8 or 9, characterized in that: The method further comprises: Cleaning is performed using a mixed solution of ozone and deionized water.

11. The method according to claim 7, characterized in that The number of rounds of wet etching is two; The first round of wet etching includes the following steps: Etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then cleaning is performed using hydrofluoric acid with a concentration of 0.5% to 2%; The second round of wet etching includes the following steps: The wet etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then the cleaning is performed using SC1 cleaning solution.

12. The method according to claim 7, characterized in that The number of rounds of wet etching is two; The first round of wet etching includes the following steps: Wet etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then cleaning is performed using SC1 cleaning solution; The second round of wet etching includes the following steps: The wet etching is performed using hydrofluoric acid with a concentration of 45% to 50%, and then the cleaning is performed using hydrofluoric acid with a concentration of 0.5% to 2%.

13. The method according to claim 11 or 12, characterized in that: The method also includes at least one cleaning process using a mixed solution of ozone and deionized water for cleaning.

14. The method according to claim 13, characterized in that The number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is single pass; The cleaning process using a mixed solution of ozone and deionized water is performed after cleaning using 0.5% to 2% hydrofluoric acid.

15. The method according to claim 13, characterized in that The number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is single pass; The cleaning process using a mixed solution of ozone and deionized water is performed after completing two rounds of wet etching.

16. The method according to claim 13, characterized in that The number of cleaning processes using a mixed solution of ozone and deionized water for cleaning is two; The cleaning process using a mixed solution of ozone and deionized water is performed after the first round of wet etching and after the second round of wet etching.

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