JP3859629B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device.

  In the process of removing the resist formed on the substrate in the manufacturing process of the semiconductor device, a plasma ashing apparatus that generates plasma made of process gas and removes the resist using the plasma is used. Furthermore, in order to effectively remove the resist, a high-density microwave plasma ashing apparatus that uses a microwave of 2.45 GHz as a power supply frequency and oxygen gas as a process gas is used.

  In the following, an ashing process using a conventional first high-density microwave plasma ashing apparatus (hereinafter referred to as an ashing apparatus) in a conventional semiconductor device manufacturing method will be described with reference to FIG.

  First, the structure of a conventional first ashing device will be described.

  As shown in FIG. 16, the first ashing apparatus includes a chamber 100 made of, for example, aluminum, a microwave waveguide 101 that guides microwaves into the chamber 100, and a microwave that is made of quartz that transmits microwaves. A transmission window 102 and an introduction path 103 for introducing, for example, oxygen gas as a process gas are provided. In addition, a stage 105 for holding the semiconductor substrate 104 is provided in the chamber 100, and the stage 105 is heated to 250 degrees in order to efficiently remove the resist formed on the semiconductor substrate 104. The ashing device and its components are all grounded in terms of potential.

  Next, an ashing process using the conventional first ashing apparatus will be described.

  A high-density oxygen plasma is generated by introducing oxygen gas, which is a process gas, into the chamber 100 and applying a microwave of 2.45 GHz. At this time, since the stage 105 is grounded, a potential difference is generated between oxygen ions and electrons due to the potential energy of the plasma, and the oxygen ions are attracted toward the semiconductor substrate 104. For this reason, the ashing process proceeds when oxygen ions collide with the resist formed on the semiconductor substrate 104.

  However, in this step, oxygen ions are attracted to the grounded stage 105 and at the same time are also attracted to the grounded chamber 100. As described above, due to the structure of the first ashing device, oxygen ions are attracted to the chamber 100 and collide with the inner wall of the chamber 100. Therefore, it is inevitable that the inner wall of the chamber 100 is etched. Therefore, metal contamination of the semiconductor substrate 104 occurs due to the metal constituting the inner wall of the etched chamber 100.

  As a countermeasure against such a problem, a method of performing an ashing process using a conventional second ashing apparatus has been proposed (see, for example, Patent Document 1).

  As shown in FIG. 17, the second ashing device has a structure in which the inner wall of the chamber 100 is covered with an organic film 106 in addition to the same configuration as the first ashing device. In this manner, the organic film 106 serves as a protective film that protects the inner wall of the chamber 100, thereby preventing the inner wall of the chamber 100 from being etched and preventing metal contamination occurring in the semiconductor substrate 104. .

JP 2000-12523 A

  However, since the ashing process proceeds mainly by a combustion reaction between oxygen and carbon, the organic film 106 formed on the inner wall of the chamber 100 easily burns. For this reason, the lifetime of the organic film 106 formed on the inner wall of the chamber 100 is remarkably short, and the inner wall of the chamber 100 is easily exposed. Therefore, the inner wall of the chamber 100 is etched, so that the semiconductor substrate 104 is contaminated with metal. Thus, in the conventional second ashing apparatus, the organic film 106 formed on the inner wall of the chamber 100 does not function sufficiently as a protective film.

  In view of the above, an object of the present invention is to provide a method of manufacturing a semiconductor device that can reduce metal contamination generated in an ashing process.

  In order to solve the above-described problem, a first method for manufacturing a semiconductor device according to the present invention is directed to plasma comprising an oxygen-containing gas on an organic film formed on a substrate disposed in a chamber. The ashing is performed, and a carbon-containing film made of a material containing carbon is formed on the inner wall of the chamber.

  According to the first method for manufacturing a semiconductor device, ashing is performed while forming a carbon-containing film on the inner wall of the chamber. Therefore, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma. In this case, metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber.

  The second method of manufacturing a semiconductor device according to the present invention uses plasma in which a gas containing silicon is added to a gas containing oxygen with respect to an organic film formed on a substrate disposed in a chamber. And a carbon-containing film made of a material containing a silicon-carbon bond is formed on the inner wall of the chamber.

  According to the second method for manufacturing a semiconductor device, ashing is performed using a plasma in which a gas containing silicon is added to a gas containing oxygen, so that many silicon-carbon bonds having excellent plasma resistance are formed on the inner wall of the chamber. An included carbon-containing film can be formed. For this reason, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma, so that the metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing.

In the second method for manufacturing a semiconductor device, the gas containing silicon is a gas made of SiH ₄ , and the flow rate ratio of the gas made of SiH ₄ to the gas containing oxygen is 3.3 × 10 ⁻³ or more. Is preferred.

  In this way, it is possible to form a carbon-containing film containing many silicon-carbon bonds on the inner wall of the chamber while preventing the inner wall of the chamber from being etched during ashing. Therefore, it is possible to prevent the substrate from being exposed directly to the plasma, so that metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing.

  According to a third method of manufacturing a semiconductor device of the present invention, a gas containing oxygen is applied to an organic film formed on a substrate disposed in a chamber provided with a member made of a material containing silicon. Ashing is performed using plasma, and a carbon-containing film made of a material containing a silicon-carbon bond is formed on the inner wall of the chamber.

  According to the third method for manufacturing a semiconductor device, since a member made of a material containing silicon is provided inside the chamber as a supply source for generating silicon atoms during ashing, the inner wall of the chamber is subjected to ashing. A carbon-containing film containing a large number of silicon-carbon bonds with excellent plasma resistance can be formed. For this reason, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma, so that the metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing. In addition, since a member made of a material containing silicon is provided in the chamber as a supply source for generating silicon atoms, normal ashing using plasma made of a gas containing oxygen may be performed as in the conventional example. Therefore, reduction of metal contamination generated on the substrate can be realized at low cost.

  In the third method for manufacturing a semiconductor device, the member made of a material containing silicon is preferably a silicon ring formed around the substrate.

  In this case, since silicon atoms are generated from the silicon ring by ashing, a carbon-containing film containing a large number of silicon-carbon bonds having excellent plasma resistance can be formed on the inner wall of the chamber during ashing. Further, as in the conventional example, normal ashing using plasma made of a gas containing oxygen may be performed, so that metal contamination generated on the substrate can be reduced at a low cost.

According to the fourth method of manufacturing a semiconductor device of the present invention, at least one of arsenic and phosphorus is implanted at 1 × 10 ¹⁶ / cm ² into the organic film formed on the substrate disposed in the chamber. And ashing the organic film into which at least one of arsenic and phosphorus is implanted using a plasma made of a gas containing oxygen, and at least one of arsenic and phosphorus on the inner wall of the chamber And a step of forming a carbon-containing film made of the containing material.

  According to the fourth method for fabricating a semiconductor device, at least one of arsenic and phosphorus is injected into the resist film, and then ashing is performed on the resist film, whereby an arsenic-carbon bond having plasma resistance on the inner wall of the chamber or A carbon-containing film containing a large amount of phosphorus-carbon bonds can be formed. For this reason, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma, so that the metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing. Further, by applying a technique called arsenic or phosphorus implantation to the organic film, metal contamination generated on the substrate can be reduced, so that the development cost can be reduced.

  According to the fifth method of manufacturing a semiconductor device of the present invention, the first ashing is performed on the organic film formed on the substrate disposed in the chamber using plasma made of an inert gas, After the step of forming a carbon-containing film made of a material containing carbon on the inner wall of the chamber and the step of forming the carbon-containing film, the organic film is subjected to second ashing using plasma made of a gas containing oxygen. And performing the process.

  According to the fifth method of manufacturing a semiconductor device, the ashing using the plasma made of the inert gas is performed before the ashing using the plasma made of the oxygen gas. Since it does not chemically react with the organic film, most of the organic film sputtered by the plasma made of inert gas is adsorbed on the inner wall of the chamber without being exhausted. For this reason, it is possible to prevent the inner wall of the chamber from being exposed and directly exposed to the plasma during ashing using a plasma made of a gas containing oxygen, so that the metal contamination generated on the substrate by etching the inner wall of the chamber Can be reduced. Further, by using an inexpensive inert gas, metal contamination generated on the substrate can be reduced, so that cost reduction can be realized.

  In the fifth method for fabricating a semiconductor device, the first ashing is preferably performed using plasma in which a gas containing chlorine is added to an inert gas.

  In this way, in addition to reducing metal contamination caused by etching the inner wall of the chamber, for example, when aluminum produced in forming the aluminum wiring remains in the chamber, aluminum and chlorine Since the residual aluminum is exhausted by the selective reaction, reduction of aluminum-based metal contamination can also be realized. Further, it is possible to cope with metal contamination caused by etching the inner wall of the chamber and aluminum-based metal contamination with the same apparatus without using different apparatuses.

  In the fifth method for manufacturing a semiconductor device, the first ashing is preferably performed using plasma in which a gas containing hydrogen is added to an inert gas.

  In this way, in addition to reducing metal contamination caused by etching the inner wall of the chamber, for example, when the dopant used for ion implantation remains in the chamber as an oxide, Since the dopant remaining as an oxide is exhausted by the reduction action, it is possible to reduce the contamination by the residual dopant. In addition, the same apparatus can be used to deal with metal contamination caused by etching of the inner wall of the chamber and contamination with residual dopant without using different apparatuses.

  In the fifth method for fabricating a semiconductor device, the first ashing is preferably performed using plasma in which a gas containing fluorine is added to an inert gas.

  In this way, in addition to reducing metal contamination caused by etching the inner wall of the chamber, tungsten and fluorine are selected when, for example, there is a tungsten film residue generated when forming a contact plug. Residual tungsten is exhausted by reaction, so that reduction of tungsten contamination can be realized. Moreover, it is possible to cope with metal contamination and tungsten contamination caused by etching the inner wall of the chamber with the same apparatus without using different apparatuses.

In the first to fifth semiconductor device manufacturing methods, it is preferable to form the carbon-containing film while cooling the chamber with liquid nitrogen.

  In this way, the deposition rate of the carbon-containing film deposited on the inner wall of the chamber is improved, and the adsorption efficiency of the carbon-containing film on the inner wall of the chamber is increased, so the formation time of the carbon-containing film can be shortened, The adhesion of the carbon-containing film to the inner wall of the chamber can be improved.

  According to the first method for manufacturing a semiconductor device, the ashing is performed while forming the carbon-containing film on the inner wall of the chamber. Therefore, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma. In this case, metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber.

  According to the second method for manufacturing a semiconductor device, ashing is performed using plasma in which a gas containing silicon is added to a gas containing oxygen, so that a silicon-carbon bond having excellent plasma resistance is formed on the inner wall of the chamber. A carbon-containing film containing a large amount can be formed. For this reason, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma, so that the metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing.

  According to the third method for manufacturing a semiconductor device, since the chamber is provided with a member made of a material containing silicon as a supply source for generating silicon atoms during ashing, the inner wall of the chamber during ashing. In addition, a carbon-containing film containing a large amount of silicon-carbon bonds having excellent plasma resistance can be formed. For this reason, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma, so that the metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing. In addition, since a member made of a material containing silicon is provided in the chamber as a supply source for generating silicon atoms, normal ashing using plasma made of a gas containing oxygen may be performed as in the conventional example. Therefore, reduction of metal contamination generated on the substrate can be realized at low cost.

  According to the fourth method for fabricating a semiconductor device, at least one of arsenic and phosphorus is injected into the resist film, and then ashing is performed on the resist film, whereby an arsenic-carbon bond having plasma resistance is formed on the inner wall of the chamber. Alternatively, a carbon-containing film containing a large amount of phosphorus-carbon bonds can be formed. For this reason, it is possible to prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma, so that the metal contamination generated on the substrate can be reduced by etching the inner wall of the chamber during ashing. Further, by applying a technique called arsenic or phosphorus implantation to the organic film, metal contamination generated on the substrate can be reduced, so that the development cost can be reduced.

  According to the fifth method for fabricating a semiconductor device, the ashing using the plasma made of the inert gas is performed before the ashing using the plasma made of the oxygen gas. Since the organic film does not chemically react with the organic film, most of the organic film sputtered by the plasma made of an inert gas is adsorbed on the inner wall of the chamber without being exhausted. For this reason, it is possible to prevent the inner wall of the chamber from being exposed and directly exposed to the plasma during ashing using a plasma made of a gas containing oxygen, so that the metal contamination generated on the substrate by etching the inner wall of the chamber Can be reduced. Further, by using an inexpensive inert gas, metal contamination generated on the substrate can be reduced, so that cost reduction can be realized.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
A method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described below with reference to FIGS. 1 (a) to 1 (c) and FIGS.

  1A to 1C are process cross-sectional views used for explaining the method for manufacturing the semiconductor device according to the first embodiment.

  First, as illustrated in FIG. 1A, a resist film 12 having an opening 12 a is formed on the protective insulating film 11 formed on the semiconductor substrate 10.

  Next, as shown in FIG. 1B, the protective insulating film 11 is dry-etched using the resist film 12 having the opening 12 a as a mask, so that the semiconductor substrate 10 is formed in the protective insulating film 11. An opening 11a reaching the upper surface is formed.

  Next, as shown in FIG. 1C, the resist film 12 formed on the protective insulating film 11 is removed by ashing.

  The manufacturing method of the semiconductor device according to the first embodiment is a method related to the ashing process described with reference to FIG. 1C, but after the processes shown in FIGS. 1A and 1B are performed. The ashing is not limited to this, and although not shown, for example, a resist film having a desired pattern is formed on the semiconductor substrate, and after processing such as ion implantation is performed on the semiconductor substrate, the ashing is performed. This method is widely used in the ashing process, for example, when the resist film is removed by ashing.

  The semiconductor device manufacturing method according to the first embodiment will be described below using a high-density microwave ashing device (hereinafter referred to as an ashing device) shown in FIG.

  The ashing device shown in FIG. 2 includes, for example, a chamber 20 formed of aluminum, a microwave waveguide 21 that guides microwaves into the chamber 20, a microwave transmission window 22 formed of quartz that transmits microwaves, and For example, an introduction path 23 for introducing a gas containing oxygen as a process gas is provided. Further, a stage 24 for holding, for example, the semiconductor substrate 10 shown in FIG. 1 is provided in the chamber 20, and the stage 24 is used for efficiently removing the resist film 12 formed on the semiconductor substrate 10. It is heated to 250 degrees. Further, an organic film 25 made of polyimide, for example, is formed on the inner wall of the chamber 20 as a protective film for ashing, as in the conventional example. Note that the ashing device and its components shown in FIG. 2 are all grounded in terms of potential.

  In such an ashing apparatus, the semiconductor device manufacturing method according to the first embodiment includes oxygen as a process gas with respect to the resist film 12 formed on the semiconductor substrate 10 disposed in the chamber 20. A carbon-containing film 26a made of a material containing many silicon-carbon bonds is formed on the inner wall of the chamber 20 while ashing is performed using plasma obtained by adding a gas containing silicon to the gas. In other words, the semiconductor device manufacturing method according to the first embodiment is characterized in that plasma obtained by adding a gas containing silicon to a gas containing oxygen is used during ashing.

  The method for manufacturing the semiconductor device according to the first embodiment will be specifically described below.

  First, a gas mainly containing oxygen as a process gas is usually introduced into the chamber 20 from the gas introduction path 23 and a microwave of 2.45 GHz is applied through the microwave waveguide 21 and the microwave transmission window 22. High density oxygen plasma is generated. Since the stage 24 provided in the chamber 20 is grounded, a potential difference is generated between oxygen ions and electrons due to the potential energy of the plasma, and the oxygen ions in the plasma are attracted toward the semiconductor substrate 10. Therefore, the ashing process proceeds when oxygen ions collide with the resist film 12 formed on the semiconductor substrate 10.

In the semiconductor device manufacturing method according to the first embodiment, as ashing conditions, for example, the flow rate of oxygen gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, and the substrate temperature is 250. The discharge time is about 1 minute at ° C. Furthermore, in the method for manufacturing a semiconductor device according to the first embodiment, silane (SiH ₄ ) gas having a flow rate of 1.2 mL / min (standard state) is supplied into the chamber 20 together with oxygen (O ₂ ) gas as a process gas. To introduce.

  In this case, the flow ratio of silane gas to oxygen gas will be described with reference to FIG.

  FIG. 3 shows the relationship between the flow rate ratio of silane gas to oxygen gas and the deposition rate (relative strength) of the carbon-containing film 26a.

As shown in FIG. 3, the flow rate ratio of silane gas to oxygen gas is desirably 3.3 × 10 ⁻³ or more. As apparent from FIG. 3, the etching rate of the organic film 25 decreases as the flow rate ratio of the silane gas increases. Then, when the flow ratio of silane gas to oxygen gas becomes 3.3 × 10 ⁻³ or more, the carbon-containing film 26 a starts to be deposited on the inner wall of the chamber 20. In addition, when silane gas is added excessively, the partial pressure of the oxygen gas in the chamber 20 decreases, and the ashing rate decreases (not shown). For this reason, in order to prevent the ashing rate from decreasing, it is desirable that the amount of silane gas added is as small as possible.

  Here, the reason why deposition of the carbon-containing film 26a proceeds by performing ashing using plasma obtained by adding silane gas to oxygen gas will be described.

  Carbon containing a large amount of silicon-carbon bonds (Si-C bonds) by causing a plasma polymerization reaction between silicon contained in the added silane gas and carbon released from the resist film formed on the semiconductor substrate 10 The containing film 26a is formed. Since the silicon-carbon bond has a high melting point and a low vapor pressure, the carbon-containing film 26a containing a large amount of silicon-carbon bonds is easily deposited, so that the inner wall of the chamber 20 can be efficiently covered.

  FIG. 4 shows a comparison between the aluminum metal contamination amount when the conventional semiconductor device manufacturing method is used and the aluminum metal contamination amount when the semiconductor device manufacturing method according to the first embodiment is used.

  As apparent from FIG. 4, according to the conventional method for manufacturing a semiconductor device, the amount of aluminum contamination tends to increase as the ashing time increases, but according to the method for manufacturing a semiconductor device according to the first embodiment. And even if ashing time increases, the tendency for the amount of aluminum contamination to increase is not seen. In addition, in the method for manufacturing a semiconductor device according to the first embodiment, the amount of aluminum contamination is reduced by about two orders of magnitude or more compared to the conventional method for manufacturing a semiconductor device. As described above, since the carbon-containing film 26a formed on the organic film 25 contains a large amount of silicon-carbon bonds, and the silicon-carbon bonds have a strong bond energy, the carbon-containing film 26a. Has plasma resistance. Therefore, since the organic film 25 can be prevented from being etched by plasma and the film thickness can be reduced, the inner wall of the chamber 20 is not directly exposed to the plasma, thereby preventing metal contamination and particles generated in the semiconductor substrate 10. it can.

  As described above, according to the method for manufacturing a semiconductor device according to the first embodiment, the ashing is performed using the plasma obtained by adding the gas containing silicon to the gas containing oxygen, so that the inner wall of the chamber 20 is plasma resistant. Thus, the carbon-containing film 26a containing a large number of silicon-carbon bonds with excellent properties can be formed. For this reason, it is possible to prevent the inner wall of the chamber 20 from being exposed by ashing and being directly exposed to the plasma, thereby reducing metal contamination and particles generated in the semiconductor substrate 10 by etching the inner wall of the chamber 20 during ashing. can do.

In the first embodiment, the case where silane (SiH ₄ ) gas is used as the gas containing silicon added to the oxygen gas has been described. However, tetramethylsilane Si (CH ₃ ) ₄ , tetraethylsilane Si (C ₂₎ Even when the gas is composed of H ₅ ) ₄ or tetraethoxysilane TEOS, the same effect as in the case of silane gas can be obtained.

  In the first embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Second Embodiment)
A method for manufacturing a semiconductor device according to the second embodiment of the present invention will be described below with reference to FIGS. 1 (a) to 1 (c) and FIG. As for the ashing process showing the semiconductor device manufacturing method according to the second embodiment, the ashing process described with reference to FIG. 1C will be described as an example, as in the first embodiment.

  FIG. 5 shows an ashing device used in the method for manufacturing a semiconductor device according to the second embodiment.

  The ashing device shown in FIG. 5 includes, for example, a chamber 30 formed of aluminum, a microwave waveguide 31 that guides microwaves into the chamber 30, a microwave transmission window 32 formed of quartz that transmits microwaves, and For example, a gas introduction path 33 for introducing a gas containing oxygen as a process gas is provided. Further, a stage 34 for holding, for example, the semiconductor substrate 10 shown in FIG. 1 is provided in the chamber 30, and the stage 34 efficiently removes the resist film 12 formed on the semiconductor substrate 10. Is heated to 250 degrees. Further, an organic film 35 made of polyimide, for example, is formed on the inner wall of the chamber 30 as a protective film for ashing, as in the conventional example. Note that the ashing device and its components shown in FIG. 5 are all grounded in terms of potential.

  In the ashing apparatus shown in FIG. 5, an Si ring 37 is provided on the stage 34 so as to cover the periphery of the semiconductor substrate 10 to be held. Here, the Si ring 37 is provided as a supply source for supplying silicon into plasma during ashing. Note that the Si ring 37 according to the second embodiment has a role greatly different from that of the Si ring generally used for adjusting the atmosphere at the center of the semiconductor substrate and the surrounding atmosphere in the etching process for the semiconductor substrate. It is to make.

  In such an ashing device, in the method of manufacturing a semiconductor device according to the second embodiment, for example, on the semiconductor substrate 10 disposed in the chamber 30 provided with a member made of a material containing silicon, such as the Si ring 37. Ashing is performed on the resist film 12 formed by using plasma made of a gas containing oxygen, and carbon made of a material containing a lot of silicon-carbon bonds (Si-C bonds) on the inner wall of the chamber 30. The containing film 36 is formed. That is, the semiconductor device manufacturing method according to the second embodiment is different from the first embodiment in which a gas containing silicon is introduced together with a gas containing oxygen, for supplying silicon into plasma during ashing. A member made of a material containing silicon is provided in the chamber 20 and ashing is performed using plasma made of a gas containing oxygen.

  The method for manufacturing the semiconductor device according to the second embodiment will be specifically described below.

  First, a gas mainly containing oxygen as a process gas is usually introduced into the chamber 30 from the gas introduction path 33 and a microwave of 2.45 GHz is applied through the microwave waveguide 31 and the microwave transmission window 32. High density oxygen plasma is generated. Since the stage 34 provided in the chamber 30 is grounded, a potential difference is generated between oxygen ions and electrons due to the potential energy of the plasma, and the oxygen ions in the plasma are attracted toward the semiconductor substrate 10. Therefore, the ashing process proceeds when oxygen ions collide with the resist film 12 formed on the semiconductor substrate 10.

In the semiconductor device manufacturing method according to the second embodiment, as ashing conditions, for example, the flow rate of oxygen (O ₂ ) gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, The substrate temperature is 250 ° C. and the discharge time is about 1 minute.

  In this case, in the ashing apparatus shown in FIG. 5, the Si ring 37 is sputtered by oxygen ions in the plasma, and silicon is supplied into the plasma. When silicon is supplied into the plasma, as in the first embodiment, silicon and carbon released from the resist film formed on the semiconductor substrate 10 cause a plasma polymerization reaction, thereby producing silicon-carbon. A carbon-containing film 36 containing a lot of bonds is formed. Since the silicon-carbon bond has a high melting point and a low vapor pressure, the carbon-containing film 36 containing a large amount of silicon-carbon bonds is easily deposited, so that the inner wall of the chamber 30 can be efficiently covered. Since the Si ring 37 provided on the stage 34 is heated to 250 ° C., a carbon-containing film containing many carbon-silicon bonds is not deposited on the Si ring 37.

  As described above, according to the semiconductor device manufacturing method according to the second embodiment, the Si ring 37 is provided in the chamber 30 so that silicon is supplied during ashing. A carbon-containing film 36 containing a lot of silicon-carbon bonds having excellent plasma resistance can be formed on the inner wall of the chamber 30. For this reason, it is possible to prevent the inner wall of the chamber 30 from being exposed by ashing and being directly exposed to the plasma, thereby reducing metal contamination and particles generated in the semiconductor substrate 10 by etching the inner wall of the chamber 30 during ashing. can do. Further, since the Si ring 37 serving as a silicon supply source is provided in the chamber 30, it is sufficient to use plasma made of a gas containing oxygen as a process gas, as in the conventional example. In addition, particle reduction can be realized at low cost.

  Further, in the second embodiment, the case where the member made of a material containing silicon as a silicon supply source is the Si ring 35 has been described. However, by providing another Si member in the chamber 30, the Si ring is provided. The same effect as in the case of 37 can be obtained.

  In the second embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Third embodiment)
A method for manufacturing a semiconductor device according to the third embodiment of the present invention will be described below with reference to FIGS. 6 (a) to 6 (d) and FIG.

  6A to 6D are process cross sections showing a method for manufacturing a semiconductor device according to the third embodiment.

  First, as shown in FIG. 6A, a resist film 42 having an opening 42a is formed on the protective insulating film 41 formed on the semiconductor substrate 40 by photolithography.

Next, as shown in FIG. 6B, arsenic (As) ions are implanted into the resist film 42. As an ion implantation condition, for example, arsenic having a dose of 1 × 10 ¹⁶ / cm ² or more is implanted. Here, although arsenic ions are implanted, it is preferable to implant at least one of arsenic and phosphorus (P).

  Next, as shown in FIG. 6C, the contact hole 41 a reaching the upper surface of the semiconductor substrate 40 is formed by performing dry etching on the protective insulating film 41 using the resist film 42 as a mask.

  Next, as shown in FIG. 6D, the resist film 42 formed on the interlayer insulating film 42 is removed by ashing.

Here, as an example, the ashing process described in FIG. 6D is performed using the ashing apparatus shown in FIG. 2 in the first embodiment described above. In this case, it is assumed that the semiconductor substrate 40 is held on the stage 24 of the ashing apparatus shown in FIG. 2, and the inner wall of the chamber 20 contains carbon, which will be described later, by ashing shown in FIG. It is assumed that the film 26b is formed. As ashing conditions, for example, the flow rate of oxygen (O ₂ ) gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and the discharge time is about 1 minute. .

As described above, in the ashing apparatus shown in FIG. 1, the semiconductor device manufacturing method according to the third embodiment is performed on the resist film 42 formed on the semiconductor substrate 40 disposed in the chamber 20. A step of implanting at least one of arsenic and phosphorus at a dose of 1 × 10 ¹⁶ / cm ² or more, and a gas containing oxygen into the resist film 42 into which at least one of arsenic and phosphorus is implanted. Ashing is performed using plasma, and a carbon-containing film 26 b made of a material containing at least one of arsenic and phosphorus is formed on the inner wall of the chamber 20. That is, the semiconductor device manufacturing method according to the third embodiment is characterized in that the carbon-containing film 26b is formed by ashing the resist film 42 implanted with at least one of arsenic and phosphorus.

  FIG. 7 shows the relationship between the arsenic dose and the deposition rate of the carbon-containing film 26b in the ashing step shown in FIG. 6 (d).

As apparent from FIG. 7, the etching rate of the organic film 25 (see FIG. 2) tends to decrease as the arsenic dose increases. When the arsenic dose is 1.0 × 10 ¹⁶ / cm ² or more, the carbon-containing film 26 ^b containing a large amount of arsenic starts to be deposited on the inner wall of the chamber 20. This is because carbon and arsenic released into the plasma from the resist film 42 formed on the semiconductor substrate 40 undergo a plasma polymerization reaction, whereby a carbon-containing film 26b containing a large amount of arsenic is formed, and a large amount of arsenic is formed. This is because the contained carbon-containing film 26 b has a strong binding energy of metal-like, so that the carbon-containing film 26 b having excellent plasma resistance can be formed on the inner wall of the chamber 20.

  As described above, according to the third method for manufacturing a semiconductor device, at least one of arsenic and phosphorus is implanted into the resist film and then ashing is performed on the resist film so that the inner wall of the chamber 20 has plasma resistance. Ashing proceeds while forming a carbon-containing film 26b containing a large amount of at least one of excellent arsenic and phosphorus. For this reason, it is possible to prevent the inner wall of the chamber 20 from being exposed by ashing and being directly exposed to plasma, so that metal contamination generated in the semiconductor substrate 40 due to etching of the inner wall of the chamber 20 during ashing is reduced. Can do. In addition, by applying a technique called arsenic or phosphorus implantation to the organic film, reduction of metal contamination occurring in the semiconductor substrate 40 can be realized at a low development cost.

  In the third embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Fourth embodiment)
A method for manufacturing a semiconductor device according to the fourth embodiment of the present invention will be described below with reference to FIGS. The ashing process shown in the method for manufacturing a semiconductor device according to the fourth embodiment will be described by taking the ashing process described in FIG. 1C as an example, as in the first embodiment.

  FIG. 8 shows an ashing device used in the method for manufacturing a semiconductor device according to the fourth embodiment.

  The ashing device shown in FIG. 8 includes a chamber 50 made of, for example, aluminum, a microwave waveguide 51 that guides microwaves into the chamber 50, a microwave transmission window 52 that is made of quartz that transmits microwaves, and A gas introduction path 53 for introducing process gas or the like is provided. Further, in the chamber 50, for example, a stage 54 for holding the semiconductor substrate 10 shown in FIG. 1 is provided. The stage 54 is used for efficiently removing the resist film 12 formed on the semiconductor substrate 10. It is heated to 250 degrees. Further, an organic film 55 made of polyimide, for example, is formed on the inner wall of the chamber 50 as a protective film for ashing, as in the conventional example. Note that the ashing device and its components shown in FIG. 8 are all grounded in terms of potential. Further, in this way, the ashing device shown in FIG. 8 is the same as the ashing device shown in FIG.

  In such an ashing apparatus, the method for manufacturing a semiconductor device according to the fourth embodiment is not suitable for the resist film 12 formed on the semiconductor substrate 10 (see FIG. 1) disposed in the chamber 50. First ashing is performed using plasma made of, for example, argon gas as the active gas, and a carbon-containing film 56 made of a material containing carbon is formed on the inner wall of the chamber 50, and then oxygen is applied to the resist film 12. Second ashing is performed using plasma made of a gas containing the same. That is, in the method of manufacturing a semiconductor device according to the fourth embodiment, before the second ashing, the carbon-containing film 56 is formed by performing the first ashing using plasma made of an inert gas. Features.

  The semiconductor device manufacturing method according to the fourth embodiment will be specifically described below.

  First, as the first ashing process, the resist film 12 formed on the semiconductor substrate 10 disposed in the chamber 50 is subjected to the first using plasma made of, for example, argon (Ar) gas as an inert gas. Ashing. Specifically, as the first ashing condition, for example, the flow rate of argon gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and the discharge time is about 1 minute.

Next, after the first ashing step, second ashing is performed on the resist film 12 using plasma made of a gas containing oxygen. Specifically, as the second ashing condition, for example, the flow rate of oxygen (O ₂ ) gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and The discharge time is about 30 seconds.

  FIG. 9 shows the deposition rates of the organic film 55 and the carbon-containing film 56 in the first ashing using plasma made of argon gas and the second ashing using plasma made of oxygen gas.

  As is clear from FIG. 9, in the first ashing using the plasma made of argon gas, the organic film 55 is not burned and the carbon-containing film 56 is always deposited. On the other hand, in the second ashing using plasma made of oxygen gas, the organic film 55 is burned and the carbon-containing film 56 is not deposited. Thus, the carbon-containing film 56 is deposited by the first ashing because the plasma made of argon gas and the resist film formed on the semiconductor substrate 10 do not chemically react. This is because most of the resist film sputtered during ashing is adsorbed on the inner wall of the chamber 50 without being exhausted.

  Next, since the semiconductor device manufacturing method according to the fourth embodiment performs the two steps of the first ashing step and the second ashing step, the time t1 during which the first ashing step is performed and the second step. The time t2 during which the ashing process is performed will be described.

  First, the total ashing time T performed in the semiconductor device manufacturing method according to the fourth embodiment is determined by the sum of the first ashing time t1 and the second ashing time t2, as shown in the following formula (1). can do.

  T = t1 + t2 (1)

  Next, the ashing amount To (constant) corresponding to the film thickness of the resist film 12 formed on the semiconductor substrate 10 is the first ashing amount in the first ashing step and the second ashing step in the second ashing step. It is indicated by the sum of the ashing amount. The first ashing amount can be determined by the product of the first ashing rate R1 (constant) and the first ashing time t1, and the second ashing amount is determined by the second ashing rate R2 (constant). ) And the second ashing time t2. Therefore, the ashing amount To can be expressed by the following formula (2).

  R1 · t1 + R2 · t2 = To (2)

  In addition, since the carbon-containing film 56 is deposited in the first ashing process, and the organic film 56 is consumed in the second ashing process, the organic film 56 is consumed and the inner wall of the chamber 50 is not exposed. The relationship between the deposition rate D1 (constant) of the carbon-containing film 56 and the consumption rate (D2) of the organic film 55 can be expressed by the following formula (3).

  D1 · t1 + D2 · t2> 0 (3)

  When relational expressions (1) to (3) are arranged, t1, t2, and T can be calculated as shown in relational expressions (4) to (6).

  Based on the equations (1) to (3), the first ashing time t1, the second ashing time t2, and the total ashing time T are represented by the following equations (4) to (6).

  t1 <To / (R1-R2 / D1 / D2) (4)

  t2 <To / (R2-R1 / D2 / D1) (5)

  T = t1 + t2 <To / (R1-R2 / D1 / D2) + To / (R2-R1 / D2 / D1) (6)

  Therefore, in the method of manufacturing a semiconductor device according to the fourth embodiment, the first ashing process and the second ashing process are performed in consideration of the above formulas (3) to (6), thereby It is possible to prevent the inner wall from being exposed and being directly exposed to the plasma.

  As described above, according to the fourth semiconductor device manufacturing method, the first ashing process using the argon gas plasma is performed before the second ashing process using the oxygen gas plasma. Therefore, the plasma made of argon gas and the resist film 12 on the semiconductor substrate 10 do not react chemically, so that most of the resist film 12 sputtered by the plasma made of argon gas is not exhausted, but the inner wall of the chamber 50 is exhausted. Adsorb to. Therefore, it is possible to prevent the inner wall of the chamber 40 from being exposed and directly exposed to the plasma during the second ashing using the plasma made of oxygen gas, so that the semiconductor substrate is etched by etching the inner wall of the chamber 50. 10 can reduce metal contamination. Further, by using an inexpensive argon gas, metal contamination generated in the semiconductor substrate 10 can be reduced, so that cost reduction can be realized.

  In the fourth embodiment, argon gas is used as the inert gas, but it goes without saying that the same effect as described above can be obtained even if helium, neon, or xenon is used.

  In the fourth embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Fifth embodiment)
A method for manufacturing a semiconductor device according to the fifth embodiment of the present invention will be described below with reference to FIGS.

  The manufacturing method of the semiconductor device according to the fifth embodiment is a manufacturing method obtained by developing the manufacturing method of the semiconductor device according to the above-described fourth embodiment, and reduces the metal contamination as in the fourth embodiment. In addition to the realization, the reduction of the contamination of the aluminum system remaining in the chamber in the previous process is also realized.

  In addition, as an apparatus used for the manufacturing method of the semiconductor device according to the fifth embodiment, the ashing apparatus shown in FIG. 8 described above will be used and related to the manufacturing method of the semiconductor device according to the fifth embodiment. Assume that the ashing process is the same as the ashing process described in FIG. 1C, for example, as in the first embodiment.

  In the fifth method for manufacturing a semiconductor device, for example, argon gas is used as an inert gas for the resist film 12 formed on the semiconductor substrate 10 (see FIG. 1) disposed in the chamber 50 (see FIG. 8). First ashing is performed using plasma formed by adding chlorine gas to the inner wall of the chamber 50, and a carbon-containing film 55 made of a material containing carbon is formed on the inner wall of the chamber 50. Second ashing is performed using plasma made of oxygen gas. That is, the semiconductor device manufacturing method according to the fifth embodiment is characterized in that, in the first ashing process, the first etching is performed using plasma in which chlorine gas is added to argon gas. This ashing step is the same as in the fourth embodiment.

  The semiconductor device manufacturing method according to the fifth embodiment will be specifically described below.

  First, as a first ashing process, plasma obtained by adding chlorine gas to argon gas as an inert gas is used for the resist film 12 formed on the semiconductor substrate 10 disposed in the chamber 50. To perform the first ashing. Specifically, as the first ashing condition, for example, the flow rate of argon gas is about 300 mL / min (standard state), the flow rate of chlorine gas is about 50 mL / min (standard state), the microwave output is 2000 W, and the chamber 50 The pressure is 5 Pa, the temperature of the semiconductor substrate 10 is 250 ° C., and the discharge time is about 1 minute.

  Next, after the first ashing step, second ashing using plasma made of a gas containing oxygen is performed on the resist film 12. Specifically, as the second ashing condition, for example, the flow rate of oxygen gas is about 300 mL / min (standard state), the microwave output is 2000 W, the pressure of the chamber 50 is 5 Pa, the temperature of the semiconductor substrate 10 is 250 ° C., And the discharge time is about 30 seconds.

  In the semiconductor device manufacturing method according to the fifth embodiment, as in the fourth embodiment, the first ashing process and the second ashing are performed in consideration of the equations (3) to (6). By performing the process, it is possible to prevent the inner wall of the chamber 50 from being exposed and directly exposed to the plasma.

  When the first and second ashing steps are performed under such conditions, the organic film 55 does not burn during the first ashing using plasma in which chlorine gas is added to argon gas. The carbon-containing film 56 is always deposited, and the aluminum remaining in the chamber 50 can be removed. This removal of residual aluminum is because chlorine and aluminum undergo a reaction as shown in the following formula (7), whereby the residual aluminum is vaporized and evacuated.

Al + 4Cl → AlCl ₄ ↑ (7)

  On the other hand, in the second ashing using the plasma made of oxygen gas, the organic film 55 is burned and the carbon-containing film 56 is not deposited, as in the fourth embodiment.

  The carbon-containing film 56 is deposited by the first ashing because the plasma made of argon gas does not chemically react with the resist film 12 on which the semiconductor substrate 10 is formed. This is because most of the resist film 12 sputtered at this time is adsorbed on the inner wall of the chamber 50 without being exhausted.

  FIG. 10 shows a comparison between the aluminum contamination amount by the semiconductor device manufacturing method according to the fifth embodiment, the aluminum contamination amount by the semiconductor device manufacturing method according to the fifth embodiment, and the aluminum contamination amount by the conventional method. Yes.

  As is apparent from FIG. 10, in the case of the semiconductor device manufacturing method according to the fifth embodiment having the first ashing process using the plasma in which chlorine gas is added to argon gas, the case of the conventional example is used. Needless to say, the amount of aluminum contamination can be greatly reduced as compared with the case of the first embodiment.

  As described above, according to the fifth method of manufacturing a semiconductor device, before performing the second ashing process using the plasma made of oxygen gas, the first using the plasma made by adding chlorine gas to argon gas. By performing this ashing step, the plasma made of argon gas and the resist film 12 on the semiconductor substrate 10 do not chemically react as in the fourth embodiment, so that most of the sputtered resist film 12 is It is adsorbed on the inner wall of the chamber 50 without being exhausted. As a result, it is possible to prevent the inner wall of the chamber 40 from being exposed and directly exposed to the plasma during the second ashing using the plasma made of oxygen gas, so that the semiconductor substrate is etched by etching the inner wall of the chamber 50. 10 can reduce metal contamination.

  Furthermore, since plasma using chlorine gas added to argon gas is used, for example, when aluminum generated by etching or the like when forming aluminum wiring in the previous process remains in the chamber 50, aluminum and Since the residual aluminum is exhausted by the selective reaction with chlorine, the reduction of aluminum-based metal contamination can be realized together. Further, metal contamination caused by etching the inner wall of the chamber 50 and aluminum metal contamination can be dealt with by the same device without using different devices.

  Moreover, since metal contamination generated on the semiconductor substrate 10 can be reduced by using inexpensive argon gas, cost reduction can be realized.

  In the fourth embodiment, argon gas is used as the inert gas, but it goes without saying that the same effect as described above can be obtained even if helium, neon, or xenon is used.

  In the fifth embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Sixth embodiment)
A method for manufacturing a semiconductor device according to the sixth embodiment of the present invention will be described below with reference to FIGS.

  The semiconductor device manufacturing method according to the sixth embodiment is a manufacturing method obtained by developing the semiconductor device manufacturing method according to the above-described fourth embodiment, and reduces metal contamination as in the fourth embodiment. In addition to the realization, for example, the reduction of contamination due to the ion-implanted dopant remaining in the chamber in the previous process is also realized.

  In addition, as an apparatus used for the manufacturing method of the semiconductor device according to the sixth embodiment, the ashing apparatus shown in FIG. 8 described above will be used and related to the manufacturing method of the semiconductor device according to the sixth embodiment. Assume that the ashing process is the same as the ashing process described in FIG. 1C, for example, as in the first embodiment.

  In the sixth method for manufacturing a semiconductor device, for example, argon gas is used as an inert gas for the resist film 12 formed on the semiconductor substrate 10 (see FIG. 1) disposed in the chamber 50 (see FIG. 8). First ashing is performed using plasma formed by adding hydrogen gas to the inner wall of the chamber 50, and a carbon-containing film 55 made of a material containing carbon is formed on the inner wall of the chamber 50. Second ashing is performed using plasma made of oxygen gas. That is, the semiconductor device manufacturing method according to the sixth embodiment is characterized in that, in the first ashing process, the first etching is performed using plasma obtained by adding hydrogen gas to argon gas. This ashing step is the same as in the fourth embodiment.

  The semiconductor device manufacturing method according to the sixth embodiment will be specifically described below.

  First, as a first ashing process, plasma obtained by adding hydrogen gas to, for example, argon gas as an inert gas is used for the resist film 12 formed on the semiconductor substrate 10 disposed in the chamber 50. To perform the first ashing. Specifically, as the first ashing condition, for example, the flow rate of argon (Ar) gas is about 300 mL / min (standard state), the flow rate of hydrogen gas is about 50 mL / min (standard state), and the microwave output is 2000 W. The chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and the discharge time is about 1 minute.

Next, after the first ashing step, second ashing using plasma made of a gas containing oxygen is performed on the resist film 12. Specifically, as the second ashing condition, for example, the flow rate of oxygen (O ₂ ) gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and The discharge time is about 30 seconds.

  In the semiconductor device manufacturing method according to the sixth embodiment, as in the fourth embodiment, the first ashing process and the second ashing are performed in consideration of the equations (3) to (6). By performing the process, it is possible to prevent the inner wall of the chamber 50 from being exposed and being directly exposed to the plasma.

  When the first and second ashing steps are performed under such conditions, the organic film 55 does not burn during the first ashing using plasma in which hydrogen gas is added to argon gas. The carbon-containing film 56 is always deposited, and boron remaining as an oxide in the chamber 50 can be removed. The removal of the residual boron is because the boron and hydrogen undergo a reaction as shown by the following formula (8), whereby the residual boron is vaporized and evacuated.

B ₂ O ₃ + 12H → B ₂ H ₆ ↑ + 3H ₂ O ↑ (8)

  On the other hand, in the second ashing using the plasma made of oxygen gas, the organic film 55 is burned and the carbon-containing film 56 is not deposited, as in the fourth embodiment.

  The carbon-containing film 56 is deposited by the first ashing because the plasma made of argon gas does not chemically react with the resist film 12 on which the semiconductor substrate 10 is formed. This is because most of the resist film 12 sputtered at this time is adsorbed on the inner wall of the chamber 50 without being exhausted.

  FIG. 11 shows a comparison between the amount of boron contamination by the semiconductor device manufacturing method according to the sixth embodiment and the amount of boron contamination by the conventional method.

  As is apparent from FIG. 11, in the case of the semiconductor device manufacturing method according to the fifth embodiment having the first ashing process using plasma in which hydrogen gas is added to argon gas, the case of the conventional example is used. Compared with, the amount of boron contamination can be greatly reduced.

  As described above, according to the fifth method of manufacturing a semiconductor device, before performing the second ashing process using the plasma made of oxygen gas, the first using the plasma made by adding hydrogen gas to argon gas. By performing this ashing step, the plasma made of argon gas and the resist film 12 on the semiconductor substrate 10 do not chemically react as in the fourth embodiment, so that most of the sputtered resist film 12 is It is adsorbed on the inner wall of the chamber 50 without being exhausted. As a result, it is possible to prevent the inner wall of the chamber 40 from being exposed and directly exposed to the plasma during the second ashing using the plasma made of oxygen gas, so that the semiconductor substrate is etched by etching the inner wall of the chamber 50. 10 can reduce metal contamination.

  Further, since a plasma in which hydrogen gas is added to argon gas is used, for example, when a dopant such as boron ion-implanted in the previous process remains in the chamber 50, the oxide is reduced by the reduction action of hydrogen. Since the remaining dopant is exhausted, the contamination due to the residual dopant can be reduced. Further, the metal contamination caused by etching the inner wall of the chamber 50 and the contamination by the dopant can be dealt with by the same device without using different devices.

  Moreover, since metal contamination generated on the semiconductor substrate 10 can be reduced by using inexpensive argon gas, cost reduction can be realized.

  In the sixth embodiment, argon gas is used as the inert gas. Needless to say, the same effect as described above can be obtained even if helium, neon, or xenon is used.

  In the sixth embodiment, the case where boron is used as a dopant has been described. However, even when phosphorus (P), arsenic (As), indium (In), or the like is a dopant, the dopant is similarly mixed with metal contamination. It is possible to achieve a reduction in contamination due to.

  In the sixth embodiment, the case where hydrogen gas is added to the argon gas in the first ashing process has been described. However, in the second ashing process, a small amount of, for example, about 5% of oxygen gas is used. The same effect can be obtained by adding hydrogen gas.

  In the sixth embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Seventh embodiment)
A method for manufacturing a semiconductor device according to the seventh embodiment of the present invention will be described below with reference to FIGS.

  The manufacturing method of the semiconductor device according to the seventh embodiment is a manufacturing method obtained by developing the manufacturing method of the semiconductor device according to the above-described fourth embodiment, and reduces the metal contamination as in the fourth embodiment. In addition to the realization, for example, the reduction of contamination by tungsten (W) remaining in the chamber in the previous process is also realized.

  In addition, as an apparatus used for the manufacturing method of the semiconductor device according to the seventh embodiment, the ashing apparatus shown in FIG. As for the ashing process, for example, as in the first embodiment, the ashing process described in FIG. 1C will be described as an example.

  In the seventh method for manufacturing a semiconductor device, an inert gas such as argon gas is applied to the resist film 12 formed on the semiconductor substrate 10 (see FIG. 1) disposed in the chamber 50 (see FIG. 8). First ashing is performed using a plasma in which a gas containing fluorine is added, and a carbon-containing film 55 made of a material containing carbon is formed on the inner wall of the chamber 50, and then the carbon-containing film 55 is formed. On the other hand, second ashing is performed using plasma made of oxygen gas. That is, the semiconductor device manufacturing method according to the seventh embodiment is characterized in that, in the first ashing step, the first etching is performed using plasma in which a gas containing fluorine is added to argon gas. The second ashing process is the same as in the fourth embodiment.

  The semiconductor device manufacturing method according to the seventh embodiment will be specifically described below.

First, as a first ashing process, plasma obtained by adding a gas containing fluorine as an inert gas, for example, an argon gas to the resist film 12 formed on the semiconductor substrate 10 disposed in the chamber 50. The first ashing is performed using. Specifically, as the first ashing condition, for example, the flow rate of argon (Ar) gas is about 300 mL / min (standard state), and the flow rate of CF ₄ gas as a gas containing fluorine (F) is about 10 mL / min ( Standard state), microwave output is 2000 W, chamber pressure is 5 Pa, substrate temperature is 250 ° C., and discharge time is about 1 minute.

Next, after the first ashing step, second ashing using plasma made of oxygen gas is performed on the resist film 12. Specifically, as the second ashing condition, for example, the flow rate of oxygen (O ₂ ) gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and The discharge time is about 30 seconds.

  In the semiconductor device manufacturing method according to the seventh embodiment, as in the fourth embodiment, the first ashing process and the second ashing are performed in consideration of the equations (3) to (6). By performing the process, it is possible to prevent the inner wall of the chamber 50 from being exposed and being directly exposed to the plasma.

  When the first and second ashing steps are performed under such conditions, the organic film 55 is combusted during the first ashing using plasma in which a gas containing fluorine is added to argon gas. In addition, the carbon-containing film 56 is always deposited and tungsten remaining in the chamber 50 can be removed. This removal of the residual tungsten is because the tungsten and fluorine cause a reaction as shown in the following formula (9), whereby the residual tungsten is vaporized and evacuated.

W + 6F → WF ₆ ↑ (9)

  On the other hand, in the second ashing using the plasma made of oxygen gas, the organic film 55 is burned and the carbon-containing film 56 is not deposited, as in the fourth embodiment.

  The carbon-containing film 56 is deposited by the first ashing because the plasma made of argon gas and the resist film 12 formed on the semiconductor substrate 10 do not chemically react, so the first ashing is performed. This is because most of the resist film 12 sputtered at this time is adsorbed on the inner wall of the chamber 50 without being exhausted.

  FIG. 12 shows a comparison between the amount of tungsten contamination by the semiconductor device manufacturing method according to the seventh embodiment and the amount of tungsten contamination by the conventional method.

  As is apparent from FIG. 12, in the case of the semiconductor device manufacturing method according to the seventh embodiment having the first ashing process using plasma in which a gas containing fluorine is added to argon gas, the conventional example is used. Compared with the case, the amount of tungsten contamination can be greatly reduced.

As described above, according to the seventh method for manufacturing a semiconductor device, before performing the second ashing process using plasma made of oxygen gas, CF ₄ gas is added as a gas containing fluorine to argon gas. By performing the first ashing process using plasma, the plasma made of argon gas and the resist film 12 on the semiconductor substrate 10 do not chemically react as in the fourth embodiment. Most of the membrane 12 is adsorbed on the inner wall of the chamber 50 without being evacuated. As a result, it is possible to prevent the inner wall of the chamber 50 from being exposed and directly exposed to the plasma during the second ashing using the plasma made of oxygen gas, so that the semiconductor substrate is etched by etching the inner wall of the chamber 50. 10 can reduce metal contamination.

Further, since a plasma in which CF ₄ gas is added as a gas containing fluorine to argon gas is used, for example, when tungsten generated in forming a contact plug in the previous process remains in the chamber 50. Since the residual tungsten is exhausted by selective reaction between tungsten and fluorine, reduction of metal contamination by tungsten can be realized together. Further, metal contamination caused by etching the inner wall of the chamber 50 and metal contamination by tungsten can be dealt with by the same device without using different devices.

  Moreover, since metal contamination generated on the semiconductor substrate 10 can be reduced by using inexpensive argon gas, cost reduction can be realized.

In the seventh embodiment, CF ₄ gas is used as the fluorine-containing gas. However, C ₄ F ₈ , C ₅ F ₈ , C ₄ F ₆ , CHF ₃ , CH ₂ F ₂ or CH Even with a gas composed of ₃ F, the same effects as described above can be obtained.

  In the seventh embodiment, argon gas is used as the inert gas. Needless to say, the same effect as described above can be obtained even if helium, neon, or xenon is used.

  In the seventh embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

(Eighth embodiment)
A method for manufacturing a semiconductor device according to the eighth embodiment of the present invention will be described below with reference to FIGS. Note that the ashing process shown in the semiconductor device manufacturing method according to the eighth embodiment. For example, the ashing process described in FIG. 1C will be described as an example, and the ashing apparatus illustrated in FIG. 8 will be used as an example.

In the method of manufacturing a semiconductor device according to the eighth embodiment, from a gas containing at least one of C ₄ F ₈ , C ₅ F ₈ , C ₄ F ₆ , CHF ₃ , CH ₂ F _2, and CH ₃ F. A step of forming a carbon-containing film 56 made of a material containing carbon on the inner wall of the chamber 50 using the plasma, and a plasma made of a gas containing oxygen on the semiconductor substrate 10 disposed in the chamber 50 thereafter. And ashing while removing the carbon-containing film 56.

  The semiconductor device manufacturing method according to the eighth embodiment will be specifically described below.

First, carbon is formed on the inner wall of the chamber 50 using a plasma made of a gas containing at least one of C ₄ F ₈ , C ₅ F ₈ , C ₄ F ₆ , CHF ₃ , CH ₂ F ₂ and CH ₃ F. For example, the carbon-containing film 56 is formed on the inner wall of the chamber 50 by seasoning using plasma made of C ₅ F ₈ gas.

As seasoning conditions here, for example, the flow rate of argon (Ar) gas is 300 mL / min (standard state), the flow rate of C ₅ F ₈ gas is about 15 mL / min (standard state), and the microwave output is 2000 W. The chamber pressure is 5 Pa, the substrate temperature is 250 ° C., and the discharge time is about 1 minute.

  Next, the semiconductor substrate 10 is carried into the chamber 20 of the ashing device in which the carbon-containing film 56 is formed.

  Next, ashing using plasma made of oxygen gas is performed on the semiconductor substrate 10 transported into the chamber 50 to remove the carbon-containing film 56 formed on the inner wall of the chamber 50 and the semiconductor substrate 10. The upper resist film 12 is removed.

  Next, the semiconductor substrate 10 is unloaded from the chamber 50.

  FIG. 13 shows a relationship between the deposition amount of the carbon-containing film 56 and the seasoning time.

  As shown in FIG. 13, the carbon-containing film 56 starts to be deposited on the inner wall of the chamber 50 immediately after the discharge is started, and the thickness of the carbon-containing film 56 increases in proportion to the increase in seasoning time. For this reason, the seasoning step and the ashing step may be performed based on the equations (3) to (6) as in the fourth embodiment.

  As described above, according to the eighth embodiment, before the ashing is performed, the carbon-containing film 56 is formed on the inner wall of the chamber 50 by seasoning, and then the ashing is performed while removing the carbon-containing film 56. Since the upper resist film 12 is removed, it is possible to prevent the inner wall of the chamber 50 from being exposed and exposed directly to the plasma during ashing, so that the inner wall of the chamber 50 is etched to form the semiconductor substrate 10. The metal contamination which arises can be reduced.

  In the eighth embodiment, the case where ashing is performed on the semiconductor substrate 10 on which the resist film 12 is formed has been described. However, the case where ashing is performed on a semiconductor substrate on which the resist film 12 is not formed is described. However, during ashing, the carbon-containing film 56 is formed on the inner wall of the chamber 50 by seasoning, so that the metal contamination that occurs in the semiconductor substrate having no resist film due to the etching of the inner wall of the chamber 50 is prevented. Can be reduced.

(Ninth embodiment)
The method for manufacturing a semiconductor device according to the ninth embodiment of the present invention will be described below with reference to FIGS. 1 (a) to 1 (c), FIG. 14 and FIG. The ashing process shown in the semiconductor device manufacturing method according to the ninth embodiment will be described by taking the ashing process described in FIG. 1C as an example, as in the first embodiment.

  FIG. 14 shows an ashing device used in the semiconductor device manufacturing method according to the ninth embodiment.

  The ashing device shown in FIG. 14 includes, for example, a chamber 80 formed of aluminum, a microwave waveguide 81 that guides microwaves into the chamber 80, a microwave transmission window 82 formed of quartz that transmits microwaves, and For example, a gas introduction path 83 for introducing a gas containing oxygen as a process gas is provided. Further, a stage 84 for holding, for example, the semiconductor substrate 10 shown in FIG. 1 is provided in the chamber 80, and the stage 84 efficiently removes the resist film 12 formed on the semiconductor substrate 10. Is heated to 250 degrees. Further, an organic film 85 made of polyimide, for example, is formed on the inner wall of the chamber 80 as a protective film for ashing, as in the conventional example. Note that the ashing device and its components shown in FIG. 14 are all grounded in terms of potential.

  The ashing apparatus shown in FIG. 14 is provided with a liquid nitrogen pipe 87 for cooling the chamber 80 on the outer wall of the chamber 80.

  In such an ashing apparatus, in the method of manufacturing a semiconductor device according to the ninth embodiment, while cooling the chamber 80 against the resist film 12 formed on the semiconductor substrate 10 disposed in the chamber 80, Ashing is performed using plasma made of a gas containing oxygen, and a carbon-containing film 86 made of a material containing carbon is formed on the inner wall of the chamber 80.

  The method for manufacturing the semiconductor device according to the ninth embodiment will be specifically described below.

  First, a gas mainly containing oxygen as a process gas is usually introduced into the chamber 80 from the gas introduction path 83 and a 2.45 GHz microwave is applied through the microwave waveguide 81 and the microwave transmission window 82. High density oxygen plasma is generated. Since the stage 84 provided in the chamber 80 is grounded, a potential difference is generated between oxygen ions and electrons due to the potential energy of the plasma, and the oxygen ions in the plasma are attracted toward the semiconductor substrate 10. Therefore, the ashing process proceeds when oxygen ions collide with the resist film 12 formed on the semiconductor substrate 10.

In the semiconductor device manufacturing method according to the ninth embodiment, as ashing conditions, for example, the flow rate of oxygen (O ₂ ) gas is about 300 mL / min (standard state), the microwave output is 2000 W, the chamber pressure is 5 Pa, The substrate temperature is 250 ° C. and the discharge time is about 1 minute.

  FIG. 15 shows the deposition rates of the organic film 85 and the carbon-containing film 86 in each case of the semiconductor device manufacturing method according to the ninth embodiment and the conventional semiconductor device manufacturing method.

  As is apparent from FIG. 15, according to the semiconductor device manufacturing method of the fifth embodiment, the carbon-containing film 86 is deposited while suppressing the combustion of the organic film 85.

  As described above, in the ashing apparatus shown in FIG. 14, the resist film 12 formed on the semiconductor substrate 10 is removed by oxygen ions in the plasma, and is efficiently adsorbed on the inner wall of the cooled chamber 80. Since it adheres firmly, the formation time of the carbon-containing film 86 can be shortened. In addition, this makes it possible to suppress the consumption of the organic film 85 formed on the inner wall of the chamber 80 and deposit the carbon-containing film 86.

  In addition, the method of performing ashing while cooling the chamber 80 in this manner is the same as that described above by applying to the case of forming the carbon-containing film while performing ashing in the first to seventh embodiments. Furthermore, the formation time of the carbon-containing film in the first to eighth embodiments can be shortened.

  As described above, according to the method of manufacturing a semiconductor device according to the ninth embodiment, the carbon-containing film 86 is formed by performing ashing while cooling the chamber 80. Since it is well adsorbed and tightly adhered, the formation time of the carbon-containing film 86 can be shortened, and the formation of the carbon-containing film 86 can prevent the inner wall of the chamber 80 from being exposed by ashing. At this time, the metal contamination generated in the semiconductor substrate 10 can be reduced by etching the inner wall of the chamber 80.

  In the ninth embodiment, the case where the ashing device is a high-density microplasma ashing device has been described. However, even if the ashing device is of a microwave downstream type, an ICP type, or a parallel plate RF type, a high-density microplasma ashing device is used. The same effect as in the case of the plasma ashing apparatus can be obtained.

  Since the ashing is performed while forming the carbon-containing film on the inner wall of the chamber, the semiconductor device manufacturing method according to the present invention can prevent the inner wall of the chamber from being exposed by ashing and being directly exposed to plasma. This is useful for reducing metal contamination that occurs in the substrate.

(A)-(c) is process sectional drawing used for description of the manufacturing method of the semiconductor device which concerns on the 1st Embodiment of this invention. It is sectional drawing of the ashing apparatus used for the manufacturing method of the semiconductor device which concerns on the 1st Embodiment of this invention. It is a related figure of the flow rate ratio and volume velocity of silane gas to oxygen gas concerning a 1st embodiment. It is a related figure of ashing time and metal contamination concerning a 1st embodiment. It is sectional drawing of the ashing apparatus used for the manufacturing method of the semiconductor device which concerns on the 2nd Embodiment of this invention. (A)-(c) is process sectional drawing which shows the manufacturing method of the semiconductor device which concerns on the 3rd Embodiment of this invention. It is a related figure of the dose amount and deposition rate concerning a 3rd embodiment. It is sectional drawing of the ashing apparatus used for the manufacturing method of the semiconductor device which concerns on the 4th Embodiment of this invention. It is a comparison figure of the deposition rate about argon gas and oxygen gas concerning a 4th embodiment. It is a figure which shows Al contamination at the time of using the plasma which consists of chlorine gas which concerns on 5th Embodiment. It is a figure which shows boron contamination at the time of using the plasma which consists of hydrogen gas which concerns on 6th Embodiment. It is a figure which shows tungsten contamination at the time of using the plasma which consists of fluorine gas which concerns on 7th Embodiment. It is a related figure of seasoning time and deposition speed concerning an 8th embodiment. It is sectional drawing of the ashing apparatus used for the manufacturing method of the semiconductor device which concerns on 9th Embodiment. It is a figure which shows the comparison with the deposition rate which concerns on 9th Embodiment, and the conventional method. It is sectional drawing of the 1st ashing apparatus used for the manufacturing method of the conventional semiconductor device. It is sectional drawing of the 1st ashing apparatus used for the manufacturing method of the conventional semiconductor device.

Explanation of symbols

10, 40 Semiconductor substrate 11, 41 Protective insulating film 12, 42 Resist film 20, 30, 50, 80 Chamber 21, 31, 51, 81 Microwave waveguide 22, 32, 52, 82 Microwave transmission windows 23, 33, 53 83 Gas introducing passages 24, 34, 54, 84 Stages 25, 35, 55, 85 Organic films 26a, 26b, 36, 56, 86 Carbon-containing films

Claims (11)

  Ashing is performed on the organic film formed on the substrate disposed in the chamber using a plasma made of a gas containing oxygen, and a carbon-containing film made of a material containing carbon is formed on the inner wall of the chamber. A method of manufacturing a semiconductor device.   Ashing is performed on the organic film formed on the substrate disposed in the chamber using plasma in which a gas containing silicon is added to a gas containing oxygen, and silicon-carbon is formed on the inner wall of the chamber. A method for manufacturing a semiconductor device, comprising forming a carbon-containing film made of a material including a bond. The gas containing silicon is a gas made of SiH ₄ ,
3. The method of manufacturing a semiconductor device according to claim 2, wherein a flow ratio of the gas made of SiH ₄ to the gas containing oxygen is 3.3 × 10 ⁻³ or more.   Ashing is performed on the organic film formed on the substrate disposed in the chamber provided with a member made of a material containing silicon by using plasma made of a gas containing oxygen, and the inner wall of the chamber And forming a carbon-containing film made of a material containing a silicon-carbon bond.   5. The method of manufacturing a semiconductor device according to claim 4, wherein the member made of a material containing silicon is a silicon ring formed around the substrate. Injecting 1 × 10 ¹⁶ / cm ² of at least one of arsenic and phosphorus into an organic film formed on a substrate disposed in a chamber;
The organic film into which at least one of the arsenic and phosphorus is implanted is ashed using plasma made of a gas containing oxygen, and at least one of the arsenic and phosphorus is applied to the inner wall of the chamber. And a step of forming a carbon-containing film made of the containing material. A carbon-containing film made of a material containing carbon on the inner wall of the chamber while performing first ashing using an inert gas plasma on an organic film formed on a substrate disposed in the chamber Forming a step;
A method of manufacturing a semiconductor device comprising: performing a second ashing on the organic film using a plasma made of a gas containing oxygen after the step of forming the carbon-containing film.   8. The method of manufacturing a semiconductor device according to claim 7, wherein the first ashing is performed using plasma in which a gas containing chlorine is added to the inert gas.   The method of manufacturing a semiconductor device according to claim 7, wherein the first ashing is performed using plasma in which a gas containing hydrogen is added to the inert gas.   10. The method of manufacturing a semiconductor device according to claim 9, wherein the first ashing is performed using plasma in which a gas containing fluorine is added to the inert gas. While cooling the chamber by liquid nitrogen, a method of manufacturing a semiconductor device according to claim 1, 2, 4, 6 or 7, characterized by forming the carbon-containing layer.

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