JP2015060934A - Plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the yield of a processed object in plasma processing.SOLUTION: In a method of plasma processing a mixture gas of halogen gas and bromine gas in a plasma processing chamber, post-processing for removing a product material containing a halogen element and nitrogen element on a sample is performed, before the sample subjected to the plasma processing is exposed to the atmosphere. Consequently, the cause and mechanism of foreign matters due to residual halogen in the plasma processing are clarified, and occurrence of the residual halogen can be prevented, or the residual halogen and nitrogen thus occurred, and other compounds can be removed.

Description

  The present invention relates to a plasma processing method, and more particularly to a plasma etching process for an object to be processed such as a semiconductor substrate.

  In a semiconductor manufacturing process, dry etching using plasma is generally performed in order to transfer a mask pattern on a resist formed by lithography to each material. In the pattern transfer in the etching process, if a foreign substance falls on the mask, the etching is hindered. This causes an abnormality in the wiring pattern such as an etching residue, resulting in a decrease in yield.

  In addition, with the miniaturization of elements corresponding to the recent high integration of devices, the particle size of foreign matter that causes a decrease in yield is also reduced, and the demand for foreign matter reduction is increasing.

  In addition, the following two can be considered as a foreign material adhering on a to-be-processed object (henceforth a sample) within a vacuum processing apparatus.

  First, (1) foreign matter generated on the inner wall of the vacuum apparatus due to corrosion of the inner wall of the vacuum apparatus or the like due to corrosion of the wall material in the vacuum apparatus is transferred to the wafer during the process of sample evacuation, evacuation, etc. It is a fallen foreign substance that falls on the (sample).

  Next, (2) residual foreign matter generated by the plasma etching process reacts and adheres to the sample surface.

  The foreign matter attributed to the residual halogen component on the sample, which is one of the above factors (2), is generated in the processing chamber on the sample by the processing process, and moisture in the atmosphere after the sample is taken out of the processing chamber. There may be various cases such as generation of foreign substances. And, it may cause serious yield reduction, such as foreign matter that occurs in vacuum as a foreign matter and hinders the etching process of the next process, increases on the substrate after being transported to the atmosphere, and can not be removed by subsequent cleaning process etc. There is.

  Patent Documents 1 and 2 describe residual components generated on a wafer after etching using a halogen-containing gas such as bromine (Br), chlorine (Cl), or fluorine (F), which is one of the above factors. The removal method of is described.

JP 2006-270030 A JP 2004-509464 A

  For example, plasma ashing and cleaning processes using oxygen are very powerful in removing residual halogen and the like, but the adoption of a metal gate structure in recent years oxidizes metal materials and affects device characteristics. There is a possibility that it cannot be used.

  And the cause and mechanism of the foreign material generated due to the above-mentioned residual halogen are not clarified, and there is a problem that no consideration is given to an appropriate operation method and post-treatment method. In addition, depending on the material of the sample to be processed, it may be etched by post-processing, which may cause surface roughness of the substrate and destruction of the formed pattern. In particular, in a metal gate structure device, the surface of the metal material is oxidized. However, there is a concern that the characteristics of the device may be impaired, and there is a problem that consideration is not given to these.

  An object of the present invention is to provide a technique capable of improving the yield of an object to be processed in plasma processing.

  Another object of the present invention is to clarify the cause and mechanism of the generation of foreign substances due to residual halogen in plasma processing, and to develop a technique that does not generate residual halogen or removes generated residual halogen and nitrogen and other compounds. It is to provide.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  The plasma processing method according to the present invention includes: (a) a step of plasma processing an object to be processed using hydrogen bromide gas in the plasma processing chamber; (b) the object to be processed that has been plasma-treated in the step (a). The step (b) is performed before the plasma-treated object to be processed in the step (a) is exposed to the atmosphere.

  In addition, the plasma processing method according to the present invention includes (a) a step of performing plasma processing on an object to be processed using a mixed gas of a halogen-containing gas and nitrogen gas in a plasma processing chamber, and (b) the step (a). And a post-processing step for removing a product containing a halogen element and a nitrogen element on the plasma-treated object. And the said (b) process is performed before exposing the said to-be-processed object plasma-processed at the said (a) process to air | atmosphere.

  Further, the plasma processing method according to the present invention includes (a) a step of plasma processing an object using a halogen-containing gas, and (b) a concentration of halogen remaining after the plasma processing in the step (a). Removing the remaining halogen until the concentration of the product containing the halogen element and the nitrogen element is not generated, (c) After the step (b), the object to be treated using nitrogen gas And a step of plasma-treating the object.

  Of the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  The yield of the object to be processed in plasma processing can be improved.

  In addition, it is possible to clarify the cause and mechanism of the generation of foreign matters due to residual halogen in plasma treatment, and to prevent residual halogen from being generated or to remove generated residual halogen and nitrogen and other compounds.

It is a block diagram which shows an example of the structure of the vacuum processing apparatus used by the plasma processing of embodiment of this invention. It is a data figure which shows an example of the measurement result of the number of the foreign materials after etching, etching by mixing an inert gas with hydrogen nitride or chlorine by the plasma processing of embodiment of this invention. It is a data figure which shows an example of the analysis result of the surface of the to-be-processed object shown in FIG. When plasma processing is performed in the same processing chamber as the plasma processing using nitrogen according to the embodiment of the present invention, when plasma processing is performed in another processing chamber, when plasma processing is performed in an unload lock chamber It is a data figure which shows an example of the measurement result of each foreign material number. It is a data figure which shows an example of the measurement result of the foreign material count after carrying out the etching by mixing hydrogen nitride and nitrogen according to the embodiment of the present invention, and adding a mixed gas such as hydrogen to argon after the etching. Etching treatment in which hydrogen nitride or chlorine is mixed in the plasma treatment according to the embodiment of the present invention, and after the etching treatment, argon and carbon tetrafluoride are added to perform a post-treatment, and the number of foreign matters after the post-treatment is measured. It is a data figure which shows an example. It is a data figure which shows an example of the analysis result of the surface of the to-be-processed object shown in FIG. It is a data figure which shows an example of the analysis result of the surface of the to-be-processed object shown in FIG. FIG. 5 is a data diagram showing an example of the analysis result of the surface of an object to be processed after performing etching by mixing hydrogen nitride and chlorine in the plasma treatment according to the embodiment of the present invention, and further performing post-treatment with oxygen after etching. is there. It is a data figure which shows an example of the analysis result of the surface of the to-be-processed object after performing the post-process by oxygen shown in FIG. It is a flowchart which shows an example of the process procedure in the plasma processing of embodiment of this invention.

  In the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

  Further, in the following embodiment, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments, but they are not irrelevant to each other unless otherwise specified. The other part or all of the modifications, details, supplementary explanations, and the like are related.

  Also, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), particularly when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and it may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps) are not necessarily indispensable unless otherwise specified and clearly considered essential in principle. Needless to say.

  Further, in the following embodiments, regarding constituent elements and the like, when “consisting of A”, “consisting of A”, “having A”, and “including A” are specifically indicated that only those elements are included. It goes without saying that other elements are not excluded except in the case of such cases. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted. Further, even a plan view may be hatched for easy understanding of the drawing.

(Embodiment)
FIG. 1 is a configuration diagram showing an example of the structure of a vacuum processing apparatus used in plasma processing according to an embodiment of the present invention.

  First, a vacuum processing apparatus 100 used in the plasma processing of this embodiment will be described with reference to FIG. A vacuum processing apparatus 100 shown in FIG. 1 includes a vacuum side block (vacuum side region) 101 and an atmosphere side block (atmosphere side region) 102. The atmosphere side block 102 includes an atmosphere transfer container 108 having an atmosphere transfer robot 109 and an alignment unit 111. A wafer cassette (FOUP) 110 capable of accommodating a plurality of samples (objects to be processed) 200 such as semiconductor wafers (semiconductor substrates) to be processed in the vacuum processing apparatus 100 is provided on the front side of the atmospheric transfer container 108. (110a, 110b, 110c).

  The vacuum side block 101 has a processing chamber 103 (103a, 103a, 103) in which the inside is depressurized and the sample 200 is transported therein and etching is performed around the side wall surface of the vacuum transport container 112 including the vacuum transport robot 107 therein. 103b), and a post-processing chamber 104 (104a, 104b) in which the inside is decompressed and the sample 200 is transported and post-processing such as ashing (ashing) is performed. Furthermore, a load lock chamber 105 for exchanging the sample 200 between the atmosphere side and the vacuum side, and an unload lock chamber (another processing chamber) 106 are provided.

  The processing chamber 103 placed in the vacuum processing apparatus 100 shown in FIG. 1 in the present embodiment is a vacuum container, a gas supply device connected to the vacuum container, and a vacuum that maintains the pressure in the vacuum container at a desired value. An exhaust system, a sample stage on which a sample (object to be processed) 200, which is a semiconductor substrate, is placed, a plasma generating means for generating plasma in a vacuum processing chamber, and the like. Then, the sample held on the sample stage is brought into a plasma state by processing the plasma supplied from the shower plate or the like placed on the opposite side of the sample stage into the vacuum processing chamber by the plasma generating means. 200 is subjected to plasma treatment.

  In the present embodiment, the plasma generation means by the microwave ECR method is used, but other discharge means such as a capacitive coupling method and an inductive coupling method using a high frequency power source may be used. The microwave ECR method is a method in which plasma of a reactive gas is formed in a processing chamber by ECR resonance of a magnetic field formed by a microwave introduced into a vacuum vessel and a solenoid coil placed around the vacuum vessel. is there.

  The post-processing chamber 104 placed on the vacuum processing apparatus 100 shown in FIG. 1 includes a vacuum container, a gas supply device connected to the vacuum container, a vacuum exhaust system that maintains the pressure in the vacuum container at a desired value, and a semiconductor. It comprises a sample stage on which a sample (object to be processed) 200 as a substrate is placed, a plasma generating means for generating a plasma different from the processing chamber 103 in the vacuum processing chamber, and the like. Then, the sample held on the sample stage is brought into a plasma state by processing the plasma supplied from the shower plate or the like placed on the opposite side of the sample stage into the vacuum processing chamber by the plasma generating means. 200 plasma treatments are performed.

  In the present embodiment, plasma generating means for forming plasma by applying high frequency power to an antenna mounted around the vacuum vessel is used. However, other discharge means can be used as in the processing chamber 103. .

  In addition, a remote plasma apparatus (remote plasma generator) 113 is mounted in at least one of the post-processing chamber 104 or the unload lock chamber 106 placed on the vacuum processing apparatus 100 shown in FIG. In this embodiment, the case where the remote plasma apparatus 113 is mounted in the unload lock chamber 106 will be described.

  The remote plasma apparatus 113 in the present embodiment is, for example, the above-described sample chamber and vacuum pipe made of quartz having excellent corrosion resistance different from the sample chamber in which the sample 200 is installed, surface-treated aluminum such as oxidation treatment, or the like. A plasma is generated by introducing a predetermined flow rate of a predetermined gas into a radical generation chamber connected at a predetermined pressure, applying a predetermined power under a predetermined pressure, and activated by the gas flow from the generated plasma. It is an apparatus that can supply the reactive gas on the sample.

  The sample chamber and radical generation chamber are connected by a vacuum pipe, but ions (charged particles) generated by plasma disappear due to collision with the wall of the vacuum pipe. Only the released radicals reach.

  In addition, by setting the processing pressure to a relatively high pressure of, for example, 100 Pa or more, it is possible to reduce the arrival of ions to the sample chamber and efficiently transport radicals. As the radical source, various plasma sources such as direct current discharge, high frequency discharge (capacitive coupling type, inductive coupling type), and microwave discharge can be used. It is preferable to use an electrodeless discharge method such as discharge.

  In addition, plasma can be generated in any pressure range such as low pressure of 1 Pa or less to atmospheric pressure, but as described above, from the viewpoint of reducing radical generation efficiency and reaching rate of ions to the sample chamber, a relatively high pressure of 100 Pa or more. It is desirable to be an area.

  Next, the examination method of the present invention performed using the processing chamber 103 and the method for suppressing foreign matter will be described. First, in order to clarify the foreign matter generation mechanism due to residual halogen, the results of the following experiment will be described below.

A sample to be treated (silicon in this embodiment) 200 in which the number of foreign substances adhered in advance is measured, a halogen-containing gas such as hydrogen bromide (HBr) or chlorine (Cl ₂ ), and nitrogen (N ₂ ) as an inert gas. ), The process is performed under the etching conditions mixed with argon (Ar), and then the number of foreign matters is measured again. Further, the number of foreign matters after the etching treatment is measured immediately after the treatment and in a clean room (temperature, humidity, etc. controlled environment). ) Was performed a total of 2 times after being left for 24 hours.

  Here, FIG. 2 is a data diagram showing an example of the measurement result of the number of foreign matter after etching after performing etching by mixing an inert gas with hydrogen nitride or chlorine in the plasma treatment according to the embodiment of the present invention, and FIG. It is a data figure which shows an example of the analysis result of the surface of the to-be-processed object shown in FIG.

In FIG. 2, hydrogen bromide (HBr) and argon (Ar), hydrogen bromide (HBr) and nitrogen (N ₂ ), chlorine (Cl ₂ ) and argon (Ar), and chlorine (Cl ₂ ) and nitrogen ( N ₂ ) is mixed for etching, and the measurement result of the number of foreign matters after etching is shown. In the present embodiment, for example, the flow rate of the halogen-containing gas such as hydrogen bromide (HBr) or chlorine (Cl ₂ ) is 150 ml / min, and the flow rates of argon (Ar) and nitrogen (N ₂ ) that are inert gases are set. 50 ml / min.

In the combination of the halogen-containing gas and nitrogen (N ₂ ), overflow (measurement impossible) occurred immediately after the treatment. Further, in the combination of halogen-containing gas and argon (Ar), chlorine (Cl ₂ ) does not generate foreign matter, but hydrogen bromide (HBr) increased by several tens in the measurement immediately after the treatment. However, it was found that the measurement after 24 hours resulted in an overflow (impossible to be measured), and the generation tendency was different depending on the halogen species.

FIG. 3 shows the result of analyzing the surface of the sample 200 after the plasma treatment in which hydrogen bromide (HBr) and nitrogen (N ₂ ) shown in FIG. 2 are mixed by X-ray photoelectron spectroscopy (XPS). The binding state of nitrogen (N ₂ ) on the surface of 200 is shown. It can be seen that N—Si bonds (398 eV) and N—C bonds (401 eV) are formed by etching treatment in which hydrogen bromide (HBr) and nitrogen (N ₂ ) are mixed.

Foreign matter (reaction product) generated by mixing halogen such as bromine (Br) or chlorine (Cl ₂ ) and nitrogen (N ₂ ) is generated immediately after processing (the generation timing is early), so that the processing chamber 103, and it was found from the result of FIG. 3 that nitrogen (N ₂ ) and silicon (Si), which is the material of the sample 200, were bonded together, and the surface of the sample 200 was nitrided. .

  Furthermore, although it is a trace amount, since formation of ammonium salt can also be confirmed (illustration omitted), it can be estimated that the ammonium salt adhered to the sample 200 and was then nitrided. In addition, foreign matters generated by argon (Ar) and hydrogen bromide (HBr) are not generated immediately after processing, but are generated by being left in the atmosphere (the generation timing is late). It is considered that bromine (Br) grew as a foreign substance by adsorbing atmospheric components such as moisture.

  As described above, when the sample 200 is plasma-treated using a mixed gas of halogen-containing gas and nitrogen gas, the mixed gas is used before the sample 200 plasma-treated using the mixed gas is exposed to the atmosphere. It is preferable to perform a post-treatment for removing a product containing a halogen element and a nitrogen element on the sample 200 that has been plasma-treated using the above. Further, when the sample 200 is plasma-treated using hydrogen nitride gas, the sample 200 plasma-treated using the hydrogen nitride gas before the sample 200 plasma-treated using the hydrogen nitride gas is exposed to the atmosphere. It is preferable to perform a post-treatment to remove nitrogen remaining in 200.

  Before the plasma-treated sample 200 is exposed to the atmosphere as described above, the post-treatment for removing the product and nitrogen on the sample 200 is performed, so that the foreign matter and the product adhere to the sample 200 or are treated. Generation and growth of foreign matter in the chamber 103 can be suppressed.

  Although there are differences in the generation timing of foreign matter and the shape of foreign matter to be formed (not shown) depending on the halogen species used in etching and the combination with the process gas, these foreign matters are residual halogen, nitrogen and other compounds. It can be estimated that it is formed. Further, it is known that the sample material is not limited to silicon but is generated regardless of the material of the sample 200 to be etched, such as a silicon oxide film, a silicon nitride film, or a titanium nitride film.

  Next, FIG. 4 shows a case where the plasma processing is performed in the same processing chamber as the plasma processing using nitrogen according to the embodiment of the present invention, the plasma processing is performed in another processing chamber, and the plasma in the unload lock chamber. It is a data figure which shows an example of the measurement result of each foreign material number at the time of processing.

  It has been found that when the halogen gas and nitrogen are directly mixed, foreign matter is formed as described above.

Therefore, FIG. 4 shows a post-treatment different from that for the processing chamber 103 when the nitrogen (N ₂ ) single plasma processing is performed in the same processing chamber 103 subjected to the halogen processing on the sample 200 processed with the halogen plasma. The result of confirming the presence or absence of the generation of foreign matter is shown in three cases when processing is performed in the chamber 104 and when processing is performed in the unload lock (UL) chamber 106 in which the remote plasma apparatus 113 is mounted.

As shown in FIG. 4, foreign matter was generated only when nitrogen (N ₂ ) treatment was performed in the processing chamber 103, and no foreign matter was generated in other cases. As a result, it is considered that a very small amount of residual halogen component remaining in the processing chamber reacted with nitrogen (N ₂ ) to generate foreign matters.

Based on the above results, in order to suppress the generation of foreign matter, the halogen gas and nitrogen (N ₂ ) are not directly mixed, or mixed with nitrogen (N ₂ ) at a halogen concentration or less that does not generate foreign matter, and nitrogen ( In the case of performing plasma processing using N ₂ ), it is performed in a post-processing chamber 104 or an unload lock chamber 106 that is different from the processing chamber 103 and does not use a halogen-containing gas as the processing gas unlike the processing chamber 103. desirable.

Further, in the case where nitrogen (N ₂ ) plasma treatment is performed in the same treatment chamber 103 after plasma treatment using a halogen gas, oxygen (O ₂ ) is added before the nitrogen (N ₂ ) plasma treatment step. It is desirable to use after reducing the residual halogen in the processing chamber to a concentration that does not generate foreign matter using a plasma cleaning step including

  Specifically, after the sample 200 is subjected to plasma processing using a gas containing halogen, and the sample 200 is subjected to plasma processing using nitrogen gas in the same processing chamber 103, the sample 200 remains after the plasma processing using halogen gas. The remaining halogen is removed until the concentration of the halogen to be reduced to a concentration that does not generate a product (foreign matter) containing the halogen element and the nitrogen element, and after removal, the sample 200 is subjected to plasma treatment using nitrogen gas. It is desirable to do. At that time, it is desirable to remove the remaining halogen by plasma cleaning using oxygen gas.

  Thereby, it is possible to prevent or suppress the generation of foreign matter on the sample 200 and in the processing chamber 103.

Next, a method for removing foreign matters generated by mixing a halogen-containing gas (F, Br, Cl, etc.) and nitrogen (N ₂ ) will be described. A sample to be processed (in this embodiment, silicon) whose number of foreign substances adhered in advance was processed under etching conditions in which hydrogen bromide (HBr) and nitrogen (N ₂ ) were mixed, and then argon (Ar) and Hydrogen (H ₂ ), argon (Ar) and carbon tetrafluoride (CF ₄ ), argon (Ar) and sulfur hexafluoride (SF ₆ ), argon (Ar) and methane gas (CH ₄ ), or oxygen (O ₂₎ The number of foreign matters was measured after each plasma post-treatment using) to confirm the presence or absence of foreign matters.

  Here, FIG. 5 shows an example of the measurement result of the number of foreign matters after the post-treatment after performing etching by mixing hydrogen nitride and nitrogen according to the embodiment of the present invention and adding a mixed gas such as hydrogen to argon after the etching. It is a data diagram.

The number of foreign matters after the etching treatment was measured twice, immediately after the treatment and after being left for 24 hours in a clean room (in an environment where temperature, humidity, etc. are controlled). FIG. 5 shows, in detail, hydrogen (H ₂ ), carbon tetrafluoride (CF ₄ ), hexafluoride after argon (Ar) after etching treatment in which hydrogen bromide (HBr) and nitrogen (N ₂ ) are mixed. It represents a sulfur (SF _6), or methane (CH ₄₎ gas mixture was added, and oxygen (O ₂₎ foreign matter results when treated after plasma by. In the present embodiment, for example, after the plasma treatment with the hydrogen bromide (HBr) flow rate of 150 ml / min, the nitrogen (N ₂ ) flow rate of 50 ml / min, the argon (Ar) flow rate of 400 ml / min, hydrogen The flow rate of (H ₂ ) is 100 ml / min, the flow rate of carbon tetrafluoride (CF ₄ ) and sulfur hexafluoride (SF ₆ ) is 20 ml / min, the flow rate of methane gas (CH ₄ ) is 4 ml / min, and oxygen (O ₂ ) Post-treatment was performed at 300 ml / min. It has been found that foreign substances can be removed by plasma post-treatment with argon (Ar), carbon tetrafluoride (CF ₄ ), and oxygen (O ₂ ).

That is, the post-treatment performed after the plasma treatment can remove foreign substances by using a mixed gas of argon (Ar) and carbon tetrafluoride (CF ₄ ) or oxygen (O ₂ ) gas. At this time, when plasma post-treatment is performed using a gas containing an oxygen element, the post-treatment can be performed in the same plasma treatment chamber (treatment chamber 103).

Next, the examination method and the result of the foreign matter removal mechanism by plasma post-treatment using a mixed gas of argon (Ar) and carbon tetrafluoride (CF ₄ ) will be described with reference to FIGS.

  Here, FIG. 6 shows an etching process in which hydrogen nitride or chlorine is mixed in the plasma process according to the embodiment of the present invention, and after the etching process, argon and carbon tetrafluoride are added to perform a post-treatment. FIG. 7 is a data diagram showing an example of the analysis result of the surface of the post-processed object shown in FIG. 6, and FIG. 8 is a result of the post-treatment shown in FIG. It is a data figure which shows an example of the analysis result of the surface of a to-be-processed object.

Specifically, FIG. 6 shows an etching process in which hydrogen bromide (HBr) and nitrogen (N ₂ ) are mixed, and then argon (Ar) and carbon tetrafluoride (CF ₄ ) or argon (Ar And hydrogen (H ₂ ) or oxygen (O ₂ ) added to carbon tetrafluoride (CF ₄ ).

In the present embodiment, for example, plasma treatment is performed with a flow rate of hydrogen bromide (HBr) of 150 ml / min and a flow rate of nitrogen (N ₂ ) of 50 ml / min, and then a flow rate of argon (Ar) of 400 ml / min. Then, after adding a flow rate of carbon tetrafluoride (CF ₄ ) to 20 ml / min, a post-treatment was performed using a gas in which hydrogen (H ₂ ) 100 ml / min or oxygen (O ₂ ) 40 ml / min was mixed.

From FIG. 6, it was found that by adding hydrogen (H ₂ ) or oxygen (O ₂ ) to argon (Ar) and carbon tetrafluoride (CF ₄ ), the post-treatment effect is reduced.

7 and 8 show the analysis results of the surface of the sample 200 by the XPS analysis after the post-treatment. FIG. 7 shows the elemental composition of the surface of the sample 200. Etching is performed by mixing hydrogen bromide (HBr) and nitrogen (N ₂ ), and the surface after the etching (Initial) is mainly composed of silicon (Si) and oxygen (O ₂ ), which are materials of the sample 200. It has become.

On the other hand, since the main components are changed to carbon (C) and fluorine (F) by the post-treatment with argon (Ar) and carbon tetrafluoride (CF ₄ ), the surface of the sample 200 has carbon. It is suggested that a thin deposit containing (C) and fluorine (F) was formed.

On the other hand, after adding hydrogen (H ₂ ) to argon (Ar) and carbon tetrafluoride (CF ₄ ), the surface fluorine (F) ratio decreases and the carbon (C) ratio increases. doing. This is because, by adding hydrogen (H ₂ ), fluorine (F) does not adhere to the sample surface and is exhausted as hydrogen fluoride (HF), and a CF-based compound such as carbon tetrafluoride (CF ₄ ). It is considered that carbon (C) that was exhausted as was left on the sample due to the decrease in fluorine (F) and deposited.

Moreover, after adding oxygen (O ₂ ) to argon (Ar) and carbon tetrafluoride (CF ₄ ), the ratio of carbon (C) and fluorine (F) on the surface decreases, and silicon (Si) And the ratio of oxygen (O ₂ ) is increasing. By adding oxygen (O ₂ ), carbon (C) deposited on the sample is exhausted as a CO-based compound such as carbon monoxide (CO) or carbon dioxide (CO ₂ ), and carbon ( It is considered that with the decrease in C), the ratio of fluorine (F) bonded to carbon (C) on the sample also decreased.

FIG. 8 shows the binding state of nitrogen (N ₂ ) on the surface of the sample 200. As described above, hydrogen bromide (HBr) and nitrogen (N ₂ ) are mixed to perform an etching process, and after the etching process (Initial), N—Si bond (398 eV) and N—C bond ( 401 eV) shows a peak. After the post-treatment of argon (Ar) and carbon tetrafluoride (CF ₄ ), which has a foreign matter removing effect, the N—Si bond (398 eV) disappears and is completely replaced by the N—C bond (401 eV).

On the other hand, after the post-treatment of adding hydrogen (H ₂ ) and oxygen (O ₂ ) to argon (Ar) and carbon tetrafluoride (CF ₄ ), the peak position shifts to an N—Si bond (398 eV), or It can be seen that peaks are shown in the N—Si bond (398 eV) and the N—C bond (401 eV).

  Next, FIG. 9 shows the result of analysis of the surface of the object to be processed after etching by mixing hydrogen nitride and chlorine in the plasma treatment according to the embodiment of the present invention, and further performing post-treatment with oxygen after etching. FIG. 10 is a data diagram showing an example of the analysis result of the surface of the workpiece after the post-treatment with oxygen shown in FIG.

9 and 10, in detail, XPS of the sample 200 in which hydrogen bromide (HBr) and nitrogen (N ₂ ) are mixed and etched, and after the etching process is post-treated with oxygen (O ₂ ). The surface analysis results are shown. Specifically, it performs the etching process in admixture with hydrogen bromide (HBr) nitrogen and (N _2), a hydrogen bromide (HBr) Nitrogen (N ₂₎ were mixed etching process in FIG. 9 Thereafter, the elemental composition of the sample surface after the post-treatment with oxygen (O ₂ ) is shown.

From FIG. 9, it can be seen that there is no significant difference between before and after the post-treatment, but the ratio of nitrogen (N ₂ ) slightly decreases.

On the other hand, FIG. 10 specifically shows the binding state of nitrogen (N ₂ ) on the sample surface. FIG. 10 shows that the N—Si bond (398 eV) disappears in the post-treatment with oxygen (O ₂ ).

6 to 10 suggest that the presence or absence of bonding between the substrate element (silicon in this embodiment) and nitrogen (N ₂ ) on the sample surface correlates with the generation of foreign matter after etching. Further, the bond between the substrate element on the sample surface (silicon in this embodiment) and nitrogen (N ₂ ) is carbon tetrafluoride (CF ₄ ), C ₄ F ₈ gas, C ₅ F ₈ gas, C By a plasma post-treatment using a fluorocarbon gas such as ₄ F ₆ gas or CHF ₃ gas, it can be replaced with a bond of carbon (C) and nitrogen (N ₂ ).

In addition, since the effect of the post-treatment is reduced by adding a gas having high reactivity with carbon (C) and fluorine (F) such as hydrogen (H ₂ ) and oxygen (O ₂ ), It is desirable to use a fluorocarbon gas such as carbon tetrafluoride (CF ₄ ), C ₄ F ₈ gas, C ₅ F ₈ gas, C ₄ F ₆ gas, CHF ₃ gas or the like.

  That is, the post-treatment is preferably performed using a fluorocarbon gas, and can be performed in the plasma processing chamber.

As described above, the foreign matter once generated by mixing the halogen-containing gas (F, Br, Cl, etc.) and nitrogen (N ₂ ) can be removed by the following two methods. The first is a plasma treatment using a gas containing carbon (C) such as carbon tetrafluoride (CF ₄ ) and fluorine (F) as a post-treatment method.

The second is post-treatment by plasma post-treatment with oxygen (O ₂ ) gas. However, depending on the material of the sample 200 to be processed, etching may be performed by post-processing using carbon tetrafluoride (CF ₄ ), which may cause surface roughness of the substrate and destruction of the formed pattern. When the sample 200 is a metal material, the surface may be oxidized by post-treatment of oxygen (O ₂ ), and the device characteristics may be changed.

Therefore, the gas containing carbon (C) and fluorine (F), such as carbon tetrafluoride (CF ₄ ), which causes the above factors, and the flow rate of oxygen (O ₂ ) such as argon (Ar) and nitrogen (N ₂ ) By diluting with an inert gas, it is possible to minimize the influence of the shape on the material to be processed and the oxidation of metal materials and the like due to the post-treatment process, and dilution with an inert gas is effective. However, as described above, when a post-treatment process in which fluorocarbon (CF ₄ ) or the like or oxygen (O ₂ ) is diluted with an inert gas is used, if the post-treatment process is performed in the treatment chamber 103, There are cases where it is difficult to remove foreign substances due to the influence of residual halogen used in this process.

  Therefore, it is desirable that the post-treatment process is performed in an environment such as the post-treatment chamber 104 that does not use a halogen-containing gas as a main process gas different from the treatment chamber 103. Further, by using the above-described remote plasma apparatus 113 shown in FIG. 1 as post-processing, damage to the material surface due to ions is reduced, and an effect of further suppressing shape influence on the sample 200 and oxidation of the metal material can be obtained. Can do. The remote plasma apparatus 113 is provided, for example, in the unload lock chamber 106, as will be described later.

  As described above, the post-treatment is preferably performed using a fluorocarbon gas or a gas containing an oxygen element. At that time, a post-treatment chamber 104 or an unload lock chamber different from the plasma treatment chamber (treatment chamber 103) is used. It is effective to perform in another processing chamber such as 106.

In addition, in the above post-treatment, not only foreign matters generated after etching treatment in which hydrogen bromide (HBr) and nitrogen (N ₂ ) are mixed, but also chlorine (Cl ₂ ), carbon tetrafluoride (CF ₄ ), etc. It is known that the present invention is also effective for removing foreign matters generated by mixing the halogen-containing gas and nitrogen (N ₂ ) and bromine (N ₂ ) remaining on the sample 200.

  Next, FIG. 11 shows a series of processes for implementing the above-described post-processing method in the above apparatus configuration. That is, FIG. 11 is a flowchart showing an example of a process procedure in the plasma processing according to the embodiment of the present invention.

  First, in the vacuum processing apparatus 100 shown in FIG. 1, the atmospheric transfer robot 109 unloads a sample (for example, a wafer) 200 from one of wafer cassettes (FOUP) 110a, 110b, and 110c (S1), and alignment (aligner). It is transported (unloaded) to the unit 111 (S2). Thereafter, alignment of the sample 200 is performed (S3), and after the execution, the sample 200 is transported to the load lock chamber 105 (S4).

  Next, the sample 200 carried into the load lock chamber 105 is placed on a sample table disposed in the load lock chamber 105. Then, after the inside of the load lock chamber 105 is depressurized (S5), the vacuum transfer robot 107 transfers (loads) the sample 200 into the processing chamber 103 via the vacuum transfer container 112 (S6) (S7).

  Thereafter, the sample 200 is subjected to plasma etching processing in the processing chamber 103 (S9). After the etching process, the plasma is post-processed in the processing chamber 103 (S10), or is carried into the post-processing chamber 104 by the vacuum transfer robot 107 through the vacuum transfer container 112 (S20) (S21).

  In the post-treatment chamber 104, plasma post-treatment (S22) or remote plasma post-treatment (S23) is performed. Thereafter, the vacuum transfer robot 107 loads the unload lock chamber 106 through the vacuum transfer container (buffer chamber) 112 (S12) (S13). After the unload lock chamber 106 is vented (S14), the atmospheric transfer robot 109 carries the wafer cassettes (FOUP) 110a, 110b, 110c installed therein (S15).

  Alternatively, after performing the plasma etching process (S9), the vacuum transfer robot 107 carries it into the unload lock chamber 106 via the vacuum transfer container 112 (S30) (S31). Then, remote plasma post-treatment (S32) is performed in the unload lock chamber 106, and further, the unload lock chamber 106 is vented (S14), and then the wafer cassette (FOUP) 110a, It is carried into 110b, 110c (S15).

  In the plasma treatment in this embodiment, plasma etching is performed in the treatment chamber 103, and then plasma is generated by the remote plasma device 113 using a gas containing an oxygen element. The post-treatment is performed by the remote plasma device 113. Plasma post-treatment using the generated plasma is performed. At that time, the plasma post-treatment is preferably performed in a different processing chamber different from the processing chamber 103 in which the plasma etching processing is performed.

  The other processing chamber is the post-processing chamber 104 or the unload lock chamber 106 for carrying the sample 200 from the vacuum side to the atmosphere side.

  According to the plasma processing method of the present embodiment, before the plasma-treated sample 200 is exposed to the atmosphere, the post-treatment for removing the product and nitrogen on the sample 200 is performed, whereby foreign matter on the sample 200 is obtained. And product adhesion, or generation and growth of foreign substances in the processing chamber 103 can be suppressed.

In addition, the formation of residual halogen, nitrogen, and other compounds is suppressed by performing a process that includes oxygen (O ₂ ) or carbon tetrafluoride (CF ₄ ) between the halogen treatment step and the subsequent nitrogen step. can do.

Further, when the residual halogen, nitrogen, and other compounds are once formed, they are different from the etching processing chamber (processing chamber 103), and are connected to another processing chamber (rear) Residual halogen, nitrogen, and other compounds can be removed by performing post-process treatment including oxygen (O ₂ ) in the treatment chamber 104 or the unload lock chamber 106).

  Therefore, in the plasma etching process, it is possible to clarify the cause and mechanism of the generation of foreign substances due to residual halogen, and as a result, no residual halogen (residual reaction product) is generated or residual halogen generated (residual reaction product). ), Nitrogen, and other compounds can be removed. At this time, the surface of the sample 200 can be removed without causing damage such as surface roughness or surface modification such as oxidation.

  Thereby, the yield of the sample 200 can be improved in the plasma processing in the device manufacturing process.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments of the invention. However, the present invention is not limited to the embodiments of the invention, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.

  Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. In addition, each member and relative size which were described in drawing are simplified and idealized in order to demonstrate this invention clearly, and it becomes a more complicated shape on mounting.

100 Vacuum processing apparatus 101 Vacuum side block 102 Atmosphere side blocks 103, 103a, 103b Processing chambers 104, 104a, 104b Post processing chamber 105 Load lock chamber 106 Unload lock chamber (other processing chamber)
107 vacuum transfer robot 108 atmospheric transfer container 109 atmospheric transfer robot 110, 110a, 110b, 110c wafer cassette 111 alignment unit 112 vacuum transfer container 113 remote plasma apparatus 200 sample (object to be processed)

Claims (10)

(A) a step of subjecting an object to plasma treatment with hydrogen bromide gas in a plasma treatment chamber;
(B) a step of performing a post-treatment to remove bromine remaining in the object to be processed that has been plasma-treated in the step (a);
Have
The step (b) is a plasma processing method which is performed before exposing the object to be processed that has been plasma-treated in the step (a) to the atmosphere. (A) a step of plasma-treating an object to be treated using a mixed gas of a halogen-containing gas and nitrogen gas in a plasma treatment chamber;
(B) a step of performing a post-treatment to remove a product containing a halogen element and a nitrogen element on the workpiece that has been plasma-treated in the step (a);
Have
The step (b) is a plasma processing method which is performed before exposing the object to be processed that has been plasma-treated in the step (a) to the atmosphere. In the plasma processing method of Claim 1 or 2,
The plasma processing method, wherein the post-processing is a plasma processing performed in the plasma processing chamber using a fluorocarbon gas. In the plasma processing method of Claim 1 or 2,
The plasma processing method, wherein the post-processing is a plasma processing performed using a fluorocarbon gas in another processing chamber different from the plasma processing chamber. In the plasma processing method of Claim 1 or 2,
The plasma processing method, wherein the post-processing is a plasma processing performed in the plasma processing chamber using a gas containing an oxygen element. In the plasma processing method of Claim 1 or 2,
The plasma processing method, wherein the post-processing is a plasma processing performed in another processing chamber different from the plasma processing chamber using a gas containing an oxygen element. In the plasma processing method according to claim 4 or 6,
The other processing chamber is a plasma processing method, which is an unload lock chamber for carrying out the object to be processed from the vacuum side to the atmosphere side. The plasma processing method according to claim 6, wherein
Plasma is generated by a remote plasma device using the gas containing the oxygen element,
The post-processing is plasma processing performed in the other processing chamber using the plasma generated by the remote plasma apparatus,
The other processing chamber is a plasma processing method, which is an unload lock chamber for carrying out the object to be processed from the vacuum side to the atmosphere side. (A) a step of plasma-treating an object to be processed using a gas containing halogen;
(B) removing the remaining halogen until the concentration of the halogen remaining after the plasma treatment in the step (a) is equal to or less than a concentration at which a product containing a halogen element and a nitrogen element is not generated;
(C) After the step (b), a step of plasma-treating the workpiece using nitrogen gas,
A plasma processing method. The plasma processing method according to claim 9, wherein
A plasma processing method, wherein the remaining halogen is removed by plasma cleaning using oxygen gas.