JP5233097B2 - Substrate processing method, substrate processing apparatus, and storage medium - Google Patents

Description

  The present invention relates to a technique for removing ammonium silicofluoride generated on a substrate as a result of performing a plasma treatment on the substrate.

  One of the semiconductor device manufacturing processes is a process of etching a substrate using plasma, but the processing technology is becoming more and more complicated as the device structure becomes more complicated and the pattern becomes finer. For this reason, a plurality of types of etching gases are often used continuously in the formation of recesses for embedding wiring, etc., so that a product made of a composite may be generated on the substrate, and the product may be generated on the substrate surface. May remain.

  For example, Cu wiring is embedded in a SiOCH film made of Si (silicon), O (oxygen), C (carbon) and H (hydrogen), which has been attracting attention as an interlayer insulating film having a low dielectric constant instead of a silicon oxide film. In the etching process for forming recesses for the purpose, for example, a SiC (silicon carbide) film which is a compound of Si and C as an etching stop film (so-called etching stopper) in order to protect the surface of the Cu wiring from the etching gas of the SiOCH film May be used. When this SiC film is etched by, for example, CF gas plasma, a CF polymer containing Si is deposited on the surface of the Cu wiring layer by this etching. This deposit increases the contact resistance and must be removed.

  On the other hand, when the Cu wiring is formed by dual damascene, a sacrificial film is often used to simultaneously form a via hole connecting upper and lower layers and a trench which is a wiring groove of each layer. An organic film is used. In some types of dual damascene, the sacrificial organic film may be etched following the SiC film etching. At this time, since it is necessary to prevent the Cu wiring exposed on the surface of the substrate from being oxidized, it is necessary to avoid the use of an etching gas containing oxygen. For example, ammonia gas is used as an etching gas for the SiC film. Processing is performed. By using ammonia gas, the aforementioned CF polymer is also etched simultaneously with the etching of the organic film, and this is an efficient process. Further, even when removing only the CF polymer generated during the etching of the SiC film, it is better to perform a removal process (plasma process) using ammonia gas subsequent to the etching of the SiC film, compared with, for example, the cleaning at the cleaning station. It is efficient.

  However, when plasma processing using a CF-based gas (in this example, etching of a SiC film) is performed in this way, CF-based deposits adhere to the processing container, so that plasma processing using ammonia gas is subsequently performed. As a result, the CF-based deposit is decomposed by the plasma and fluorine is released into the processing atmosphere. As a result, for example, ammonium silicofluoride is generated on the entire surface of the silicon-containing film of the substrate. Since this compound is harmful to the human body, if the substrate is carried out to the working atmosphere outside the processing apparatus with this compound attached to the substrate, the concern of adversely affecting the health of the worker cannot be wiped out. Further, this compound has a hygroscopic property, and by absorbing water having a high dielectric constant, the dielectric constant of the wafer may be increased, and the barrier metal and wiring material may be oxidized. The compound needs to be removed from the surface of the substrate.

  Patent Document 1 describes a technique for cleaning a wafer using water, alcohol, or the like using the hygroscopicity (solubility in water) of this compound. If it penetrates into the SiOCH film, it will cause an increase in dielectric constant, and if the wiring metal is exposed, the surface of the wiring metal will be oxidized.

  Patent Document 2 describes a method for cleaning ammonium silicofluoride adhering to the inside of a chamber by using nitrogen trifluoride gas and oxygen gas. However, the removal of ammonium silicofluoride adhering to a substrate is described. Is not listed.

JP-A-2005-191275 ((0006), (0008), FIG. 2) JP-A-2005-85956 ((0041) to (0045))

  The present invention has been made under such circumstances, and an object of the present invention is to provide a technology capable of removing harmful ammonium fluorosilicate generated on a substrate by plasma treatment and preventing adverse effects on the human body. It is to provide.

In the substrate processing method of the present invention, in order to remove the etching stop film containing silicon and carbon formed on the surface of the metal wiring at the bottom of the concave portion of the film on the substrate formed by etching, the substrate is processed. A step (a) of exposing a processing gas containing fluorine in a processing container to plasma generated by plasma;
In order to remove the organic film formed as a by-product on the metal wiring in the step (a), the processing gas containing nitrogen and hydrogen is converted into plasma in the processing vessel in which the step (a) is performed. A step (b) in which ammonium silicofluoride is produced on the substrate by exposure to the plasma produced in the step;
Next, before the substrate is placed in a clean room atmosphere, the substrate is heated in the processing container to a temperature equal to or higher than the decomposition temperature of the ammonium silicofluoride.
In another substrate processing method of the present invention, plasma processing is performed with a processing gas containing fluorine in a processing container on a substrate in which a film containing silicon and carbon is exposed in a recess, whereby the film containing silicon and carbon is obtained. And a step (a) of generating a CF-based deposit containing silicon in the recess,
Next, a step (b) of removing the deposits in the concave portion and forming ammonium silicofluoride on the inner surface of the concave portion by plasma of a processing gas containing nitrogen and hydrogen with respect to the substrate in the processing container. ,
Then, before the substrate is placed in a clean room atmosphere, the substrate is heated and removed in the processing container to a temperature higher than or equal to the decomposition temperature of ammonium silicofluoride (c) .

The substrate processing apparatus of the present invention is a substrate processing apparatus for performing processing on a substrate in which a film containing silicon and carbon is exposed in a recess,
A step of performing plasma treatment with a treatment gas containing fluorine on the substrate in a treatment container, thereby etching the film containing silicon and carbon and generating a CF-based deposit containing silicon in the recess. (A) and
Next, a step (b) of removing the deposits in the concave portion and forming ammonium silicofluoride on the inner surface of the concave portion by plasma of a processing gas containing nitrogen and hydrogen with respect to the substrate in the processing container. ,
Next, before the substrate is placed in a clean room atmosphere , a control signal is output so as to perform the step (c) of removing the substrate by heating it to a temperature higher than the decomposition temperature of ammonium silicofluoride in the processing container. It has the part.

The storage medium of the present invention is
A storage medium storing a computer program used on a substrate processing apparatus for processing a substrate in a processing container and operating on a computer,
In the computer program, steps are set so as to perform the above-described substrate processing method.

  In the present invention, a plasma treatment is performed on a substrate on which a film containing silicon is formed, and after the ammonium silicofluoride is generated on the substrate, the substrate is subjected to a heat treatment before being placed in an air atmosphere. Since harmful ammonium silicofluoride is removed, there is no possibility of adversely affecting the human body, and ammonium silicofluoride can be easily removed.

  An example of a substrate processing apparatus for carrying out the substrate processing method of the present invention will be described with reference to FIG. The substrate processing apparatus 11 shown in FIG. 1 is called a cluster tool or a multi-chamber for performing plasma processing and heat processing described later, and includes carrier chambers 12a to 12c, a first transfer chamber 13, and a load lock chamber. 14, 15, a second transfer chamber 16, plasma processing apparatuses 51 to 53, and a heating apparatus 54. An alignment chamber 19 is provided on the side surface of the first transfer chamber 13. The load lock chambers 14 and 15 are provided with a vacuum pump and a leak valve (not shown) so as to be switched between an air atmosphere and a vacuum atmosphere.

  The first transfer chamber 13 and the second transfer chamber 16 are respectively provided with a first transfer means 17 and a second transfer means 18. The first transfer means 17 is a transfer arm for transferring the wafer W between the carrier chambers 12 a to 12 c and the load lock chambers 14 and 15 and between the first transfer chamber 13 and the alignment chamber 19. These are configured to be movable in the left-right direction in the figure. The second transfer means 18 is a transfer arm for delivering the wafer W between the load lock chambers 14 and 15 and the plasma processing apparatuses 51 to 53 and the heating apparatus 54. For example, two arms are the second arms. It is configured to be able to rotate and expand and contract about the approximate center of the transfer chamber 16.

  As shown in FIG. 2, the plasma processing apparatus 51 is provided on a processing container 21 composed of a vacuum chamber, a mounting table 3 disposed in the center of the bottom surface in the processing container 21, and an upper surface portion of the processing container 21. The upper electrode 4 is provided.

  The processing container 21 is electrically grounded, and an exhaust device 23 including a vacuum pump or the like is connected to an exhaust port 22 on the bottom surface of the processing container 21 via an exhaust pipe 24. A transfer port 25 for the wafer W is provided on the wall surface of the processing chamber 21, and the transfer port 25 can be opened and closed by a gate valve 26.

The mounting table 3 includes a lower electrode 31 and a support 32 that supports the lower electrode 31 from below. The mounting table 3 is disposed on the bottom surface of the processing vessel 21 via an insulating member 33. An electrostatic chuck 34 is provided on the top of the mounting table 3, and a wafer W is electrostatically attracted onto the mounting table 3 by applying a voltage from a high-voltage DC power supply 35.
A temperature adjustment flow path 37 through which a predetermined temperature adjustment medium passes is formed in the mounting table 3, and the temperature of the wafer W is adjusted to a desired temperature by the temperature adjustment medium.

  In addition, a gas flow path 38 for supplying a heat conductive gas such as He (helium) gas as a backside gas is formed inside the mounting table 3. Open at some points. These openings communicate with the through hole 34 a provided in the electrostatic chuck 34.

The lower electrode 31 is grounded via a high pass filter (HPF) 3a, and a high frequency power source 31a having a frequency of 2 MHz, for example, is connected to the lower electrode 31 via a matching unit 31b.
A focus ring 39 is disposed on the outer peripheral edge of the lower electrode 31 so as to surround the electrostatic chuck 34. The plasma is focused on the wafer W on the mounting table 3 through the focus ring 39 when plasma is generated. ing.

  The upper electrode 4 is formed in a hollow shape, and a plurality of holes 41 for distributing and supplying the processing gas into the processing vessel 21 are arranged on the lower surface thereof, for example, to constitute a gas shower head. A gas introduction pipe 42 is provided at the center of the upper surface of the upper electrode 4, and the gas introduction pipe 42 penetrates the center of the upper surface of the processing vessel 21 through an insulating member 27. The gas introduction pipe 42 is branched into five on the upstream side to form branch pipes 42A to 42E, which are connected to gas supply sources 45A to 45E via valves 43A to 43E and flow rate control units 44A to 44E. Yes. The valves 43A to 43E and the flow rate control units 44A to 44E constitute a gas supply system 46.

The upper electrode 4 is grounded via a low-pass filter (LPF) 47, and the upper electrode 4 is provided with a high-frequency power source 4a which is a high-frequency, for example, 60 MHz plasma generating means having a higher frequency than the high-frequency power source 31a. 4b is connected.
The high frequency from the high frequency power source 4a connected to the upper electrode 4 is for converting the processing gas into plasma, and the high frequency from the high frequency power source 31a connected to the lower electrode 31 applies bias power to the wafer W. In this way, ions in the plasma are attracted to the surface of the wafer W.

  As shown in FIG. 3, the heating device 54 includes a mounting table 92 in which a processing vessel 91 and a heater 98 as heating means are embedded. The heater 98 can raise the temperature of the wafer W to the decomposition temperature of the above-described ammonium silicofluoride 81, for example, a temperature of 100 ° C. or higher. A suction port 96 is formed on the lower surface of the processing container 91, and the atmosphere in the processing container 91 is exhausted by a vacuum pump 97 serving as an exhaust means connected to the upstream side. The vacuum pump 97 is connected to a detoxification device (not shown) so that the exhaust gas of the vacuum pump 97 flows into the vacuum pump 97, and harmless the gas of ammonium silicofluoride 81 (described later) decomposed by the heat treatment of the wafer W. It is configured to become. A gas supply port 95 is formed at a position facing the wafer W on the upper surface of the processing container 91 so that, for example, nitrogen gas or the like can be supplied from the gas source 94 into the processing container 91. An opening 93a for carrying in / out the wafer W is formed on the side surface of the processing container 91, and is opened and closed by the gate valve 93b.

  Further, as shown in FIG. 1, the substrate processing apparatus 11 is provided with a control unit 2A composed of, for example, a computer, and this control unit 2A includes a data processing unit composed of a program, a memory, and a CPU. In the program, a command is incorporated so that a control signal is sent from the control unit 2A to each part of the substrate processing apparatus 11, and each step described later is performed to process and transfer the wafer W. In addition, for example, the memory includes an area in which processing parameter values such as processing pressure, processing temperature, processing time, gas flow rate, and power value are written, and these processing parameters are stored when the CPU executes each instruction of the program. The control signal is read out and a control signal corresponding to the parameter value is sent to each part of the substrate processing apparatus 11. This program (including programs related to processing parameter input operations and display) is stored in the storage unit 2B such as a computer storage medium such as a flexible disk, a compact disk, or an MO (magneto-optical disk) and installed in the control unit 2A.

  Next, an example of the substrate processing method of this invention using this substrate processing apparatus 11 is demonstrated. First, a carrier, which is a transfer container for the wafer W, is loaded into one of the carrier chambers 12a to 12c from the atmosphere via the gate door GT, and then the wafer W is transferred to the first transfer chamber 13 via the first transfer means 17. Carry in. Next, the wafer W is transferred to the alignment chamber 19 through the first transfer means 17 and the orientation of the wafer W is adjusted, and then transferred to the load lock chamber 14 (or 15). After decompressing the atmosphere in the load lock chamber 14, the wafer W is transferred from the load lock chamber 14 to the plasma processing apparatus 51 through the second transfer chamber 16 and the gate valve 26 by the second transfer means 18.

  After the wafer W is horizontally mounted on the mounting table 3 in the processing container 21, the second transfer means 18 moves away from the processing container 21 and the gate valve 26 is closed. Subsequently, backside gas is supplied from the gas flow path 38 to adjust the wafer W to a predetermined temperature. Then perform the following steps:

  Here, the structure of the surface portion of the wafer W is shown in FIG. This wafer W represents the structure of the film according to the first embodiment of the present invention. FIG. 4A shows the n-th layer (n is an integer of 1 or more), the SiO2 film 71 and the organic film. An example of an intermediate stage of the process of forming the (n + 1) th wiring layer on the insulating film made of 72 and the copper wiring 73 formed therein is shown. In the figure, the copper wiring for connecting to the (n-1) th layer in the nth layer is omitted. On the copper wiring 73, an SiC film 74 as an etching stop film, an SiOCH film 75 as an interlayer insulating film, an organic film 76, and an SiO2 film 77 as a hard mask are formed in this order from the bottom. In the SiOCH film 75 and the organic film 76, a recess 79 for removing a via hole is formed. The recess 79 is formed by a conventional method such as a dry etching method using a photoresist mask, but the description thereof is omitted here.

(Step 1: Etching process of SiC film 74)
After exhausting the inside of the processing vessel 21 through the exhaust pipe 24 by the exhaust device 23 and maintaining the inside of the processing vessel 21 at a predetermined degree of vacuum, CF4 gas, for example, is supplied as a processing gas from the gas supply system 46. Subsequently, a high frequency with a frequency of 60 MHz is supplied to the upper electrode 4 to turn the processing gas into plasma, and a high frequency with a frequency of 2 MHz is supplied to the lower electrode 31 as a high frequency for bias.

  This plasma contains active species of a compound of carbon and fluorine. When the SiC film 74 is exposed to the atmosphere of these active species, a compound that reacts with atoms in the film is generated. As shown in FIG. 4B, the SiC film 74 is etched. At this time, a CF-based polymer (deposit) 80 containing silicon, which is a reaction product of the SiC film 74 and the processing gas, is deposited on the surface of the copper wiring 73 by etching the SiC film 74. Further, CF-based polymer is deposited on the inner wall of the processing vessel 21 by the etching at this time.

  In this example, CF4 gas is used, but other CF gas such as C2F6 gas such as carbon and fluorine gas may be used. Further, the etching stop film is not limited to the SiC film 74 but may be a film containing silicon and carbon, for example, a SiCN film. The CF4 gas may be mixed with an inert gas such as nitrogen gas.

(Step 2: Ammonia treatment process)
After the SiC film 74 is etched, the power supply from the high-frequency power sources 4a and 31a is stopped to stop the generation of plasma in the processing vessel 21, and then the gas supply from the gas supply system 46 is stopped. Next, the inside of the processing vessel 21 is exhausted by the exhaust device 23 to remove the remaining gas, and the inside of the processing vessel 21 is maintained at a predetermined degree of vacuum.

  Next, a gas containing nitrogen and hydrogen, for example, ammonia gas is supplied from the gas supply system 46 to maintain the inside of the processing vessel 21 at a predetermined pressure, and then a high frequency with a frequency of 60 MHz is supplied to the upper electrode 4 to perform the processing. While the gas is turned into plasma, a high frequency of 2 MHz is supplied to the lower electrode 31 as a high frequency for bias.

  As shown in FIG. 4C, the plasma removes the polymer 80 deposited on the surface of the copper wiring 73 and etches the organic film 76 using the SiO2 film 77 as a mask to embed the copper wiring. A groove is formed. In this step, for example, the use of ammonia gas without using oxygen gas suppresses the oxidation of the copper wiring 73 exposed on the surface of the wafer W by the removal of the polymer 80 and forms it on the surface of the copper wiring 73. This is to reduce the slight oxide film formed.

  By performing this treatment, a white powdery product is deposited on the surface of the wafer W. This product is a compound containing silicon, fluorine, nitrogen and hydrogen, for example, ammonium silicofluoride 81 whose chemical formula is represented by (NH4) 2SiF6.

  This ammonium silicofluoride 81 is presumed to be produced as follows. That is, the etching of the SiC film 74 causes the CF-based polymer to be deposited on the inner wall of the processing vessel 21 as described above. Therefore, when ammonia gas is subsequently converted into plasma, the CF-based polymer is transformed by the plasma. Dissociates to generate fluorine. The fluorine adheres to the surface of the wafer W and reacts with silicon and ammonia gas in the film on the surface of the wafer W, so that ammonium silicofluoride 81 is generated on the entire surface of the wafer W.

  Here, the ammonium silicofluoride 81 is a compound in which the stoichiometric ratio of each constituent element is not limited to the above-described chemical formula, and the properties (toxicity, hygroscopicity, and thermal decomposition temperature) of this compound are approximately the same. There may be. In this example, ammonia gas is used as the gas containing nitrogen and hydrogen. However, for example, hydrazine-based gas may be used.

Next, the wafer W that has been subjected to the ammonia treatment is again taken out into the second transfer chamber 16 by the second transfer means 18 and transferred to the heating device 54.
(Step 3: heating process)
Next, the wafer W is mounted on a mounting table 92 in the heating device 54, and the inside of the processing container 91 is maintained at a predetermined degree of vacuum by the vacuum pump 97 while supplying nitrogen gas from the gas source 94 into the processing container 91. To do. Next, the wafer W is heated to, for example, 150 ° C. by the heater 98 embedded in the mounting table 92 and held for 150 seconds. By this heat treatment, as shown in FIG. 4D, the above-described ammonium silicofluoride 81 deposited on the surface of the wafer W is decomposed, for example, hydrogen fluoride (HF), silicon fluoride (SiF4), or the like. Produces. These products are sucked together with nitrogen gas through a vacuum pump 97 to a detoxification device (not shown) and rendered harmless. In this example, the heat treatment temperature is set as described above. However, if the temperature is higher than the temperature at which ammonium silicofluoride 81 is decomposed and lower than the heat resistance temperature (about 400 ° C.) of the interlayer insulating film (in this example, SiOCH film 75), there is no particular limitation. Further, the holding time may be a time that allows the ammonium silicofluoride 81 to be sufficiently decomposed.
Thereafter, the wafers W are unloaded from the substrate processing apparatus 11 in the reverse order of the loaded order.

  According to the above-described embodiment, following the plasma treatment using CF4 gas, which is the etching treatment of the SiC film 74, the removal of the CF-based polymer 80 and the removal of the organic film 76 that are residues during the etching treatment. Therefore, harmful ammonium silicofluoride 81 is generated on the surface of the wafer W because the plasma treatment using ammonia gas is performed. However, the wafer W is removed after being removed by the heat treatment in the substrate processing apparatus 11. Since it is carried out to the air atmosphere (clean room atmosphere) outside the substrate processing apparatus 11, there is no possibility that the inside of the clean room is contaminated by the ammonium silicofluoride 81, and there is no possibility that the ammonium silicofluoride 81 directly adheres to the operator. Therefore, it is possible to prevent harmful effects caused by harmful substances generated during the semiconductor manufacturing process. You can stop.

  Further, by removing the highly hygroscopic ammonium silicofluoride 81, it is possible to suppress the oxidation of the copper wiring 73 and the like due to moisture absorption, and it is possible to prevent water having a high dielectric constant from being absorbed into the wafer W. An increase in dielectric constant can be suppressed.

  As a method for removing the ammonium silicofluoride 81, heat treatment is performed instead of cleaning with water or the like. Therefore, the ammonium silicofluoride 81 can be removed by a simple method and the SiOCH film 75 that is a porous body can be removed. Since water used for cleaning does not enter the inside, an increase in the dielectric constant can be suppressed, and there is no need to perform a process of removing the water that has entered the wafer W.

In this example, the plasma treatment and the heat treatment are performed in the separate processing vessels 21 and 91. However, a heater is provided on the mounting table 3 in the plasma processing apparatus 51 so that the processing vessel 21 is heat-treated. Both processes may be performed in the same processing container 21 so as to serve as the container 91. Further, the heating means for heating the wafer W is not limited to the heater 98, and may be an infrared lamp, for example.
The heating device 54 may be provided in combination with the load lock chambers 14 and 15. In this case, a heater is provided on a mounting table (not shown) in the load lock chambers 14 and 15, For example, an infrared lamp may be provided on the top wall of the ceiling, so that a purge gas can be supplied.

  In addition, in the process of removing the polymer 80 that is a residue when the SiC film 74 is etched, the organic film 76 is etched to form a part of the recess 79 that is a trench groove. A process that does not involve the process of removing the film 76 may be used. In addition, the plasma treatment with the fluorine-containing gas is not limited to the etching of the SiC film 74, and may be another plasma treatment, which is a plasma treatment using ammonia gas following the plasma treatment. The organic film 76 containing silicon may be etched. The former example will be described with reference to FIGS.

  In the second embodiment of the present invention, as shown in FIG. 5, an SiC film 103 as an etching stop film, a SiOCH film 104 as an interlayer insulating film, and a SiO 2 film as a hard mask are formed on the copper wiring 110. 105 and the organic film 107 which is a sacrificial film are formed in this order from the bottom. A trench groove 106 a is formed in the SiOCH film 104, the SiO 2 film 105, and the organic film 107, and the groove 106 a is formed, for example, to a depth about half that of the SiOCH film 104. In addition, a hole 106b is formed in the SiOCH film 104 so as to communicate with the SiC film 103 from the groove 106a, and the organic film 107a made of the same material as the organic film 107 described above is embedded in the hole 106b. ing.

In this case, the wafer W is mounted on the mounting table 3 in the processing container 21, and plasma processing similar to that described above is performed using O2 gas or ammonia gas as the processing gas, as shown in FIG. Then, the organic film 107 on the surface of the wafer W and the organic film 107a in the hole 106b are etched. Subsequently, as shown in FIG. 6B, the SiC film 103 is etched by plasma processing using CF4 gas in the same manner, and further, plasma processing using ammonia gas is performed in the same manner as shown in FIG. As shown, the polymer 80 which is a residue at the time of etching of the SiC film 103 deposited on the surface of the copper wiring 110 is removed. Also in this case, as described above, ammonium silicofluoride 81 is generated on the surface of the wafer W.
Next, the wafer W is carried into the heating device 54 and the same heat treatment is performed.
Also in this embodiment, the same effect as the above-described embodiment can be obtained.

An example of another substrate processing apparatus to which the substrate processing method of the present invention is applied will be briefly described with reference to FIG.
The substrate processing apparatus 121 shown in FIG. 7 includes carrier chambers 122a to 122c, a transfer chamber 123, load lock chambers 124 and 125, and plasma processing apparatuses 51 and 52. An alignment chamber 129 is provided on the side surface of the transfer chamber 123.

  The transfer chamber 123 is provided with a first transfer means 127. The first transfer means 127 is provided between the carrier chambers 122a to 122c and the load lock chambers 124 and 125, and between the transfer chamber 123 and the alignment chamber 129. , And a transfer arm for transferring the wafer W to the left and right in the drawing. Further, as shown in FIG. 8, the load lock chambers 124 and 125 are provided with second transfer means 128a and 128b, respectively, and the second transfer means 128a and 128b are provided with the first transfer means 127, respectively. And a transfer arm for transferring the wafer W between the plasma processing apparatuses 51 and 52. In addition, an infrared lamp 135 as a heating means is provided above the load lock chambers 124 and 125, and the wafer W in the load lock chambers 124 and 125 is irradiated with infrared rays through a transparent window 136 made of glass or the like. Thus, the wafer W is configured to be heated to a temperature equal to or higher than the decomposition temperature of the ammonium silicofluoride 81, for example, 100 ° C. or higher.

  The load lock chambers 124 and 125 are connected to vacuum pumps 131a and 131b as exhaust means via exhaust pipes 130a and 130b, respectively, so that the load lock chambers 124 and 125 can be evacuated. A detoxification device (not shown) is connected to the upstream side of the vacuum pumps 131a and 131b so that the gas generated by the decomposition of the ammonium fluorosilicate 81 generated from the load lock chambers 124 and 125 can be rendered harmless. The load lock chambers 124 and 125 are connected to a gas source 134 capable of supplying, for example, nitrogen gas via gas supply pipes 132a and 132b, so that gas can be supplied to the load lock chambers 124 and 125, respectively. It is configured. The load lock chambers 124 and 125 include a leak valve (not shown), and are configured to be switched between an air atmosphere and a vacuum atmosphere by the leak valve and the above-described vacuum pumps 131a and 131b. For example, a cooling means including a cooling gas source and a gas supply path is connected to the load lock chambers 124 and 125 so that the wafer W after the heat treatment can be cooled, but is omitted here. . FIG. 8 illustrates the load lock chamber 124.

  In the substrate processing apparatus 121, the wafer W is transferred from the carrier chamber 122a (122b, 122c) to the transfer chamber 123, the alignment chamber 129, the transfer chamber 123, the load lock chamber 124 (or 125), and the plasma processing apparatus 51 (52). In this order, the above-described plasma processing is performed, and then, the second transfer means 128a (128b) is carried into the load lock chamber 124 (125). Then, the wafer W is heated to, for example, 100 ° C. or more by the infrared lamp 135 to decompose the ammonium silicofluoride 81 on the surface of the wafer W. Thereafter, air flows into the load lock chamber 124 (125) from a leak valve (not shown), and the wafer W is transferred from the substrate processing apparatus 121 in the reverse order to the order in which the wafer W was loaded into the load lock chamber 124 (125). It is carried out.

  Next, an experiment performed on the substrate processing method of the present invention will be described. In the experiment, as shown in FIG. 9, each example is performed using a substrate processing apparatus 11 on a wafer W on which an SiC film 83 is formed to have a film thickness of 100 nm on an experimental bare silicon wafer. The following processing was performed for each. Thereafter, using a time-of-flight secondary ion mass spectrometer (ToF-SIMS), the surface of the wafer W was sputtered with gold ions to analyze the components of the deposited compounds.

Note that the following conditions were used when processing the wafer W.
(Etching of SiC film 83)
Processing pressure: 6 Pa (45 mTorr)
Processing gas: CF4 = 100 sccm
Processing time: 15 sec
This etching was performed without forming a resist film or the like on the surface of the SiC film 83.
(Ammonia treatment)
Processing pressure: 40 Pa (300 mTorr)
Processing gas: Ammonia = 700 sccm
Processing time: 40 sec
(Heat treatment)
Heating temperature: 150 ° C
Degree of vacuum: 1.3 Pa (100 mTorr)
Holding time: 150 seconds (Example 1)
Etching, ammonia treatment, and heat treatment of the SiC film 83 described above were performed on the wafer W according to the steps described above.
(Example 2)
The same processing as in Example 1 was performed on the wafer W. However, in order to ascertain the extent of the influence of moisture in the atmosphere, after etching the SiC film 83 and ammonia treatment in the plasma processing apparatus 51, the wafer W is once returned to the carrier chamber 12a which is an atmospheric atmosphere, and again. The wafer W was transferred to the heating device 54 and subjected to heat treatment.
(Comparative example)
Etching of the SiC film 83 and ammonia treatment were performed on the wafer W in this order.
(Reference example)
The SiC film 83 described above was etched on the wafer W.
(Experimental result)
The result of this experiment is shown in FIG.

  In each of the above examples, it was confirmed that various compounds (numbers 1 to 14 in the legend in the figure) considered to be caused by decomposition of ammonium silicofluoride 81 were generated. Although these compounds were also confirmed in Examples 1 and 2, since the production amount was almost the same level as the result of the reference example, these products in Examples 1 and 2 were not contained in the wafer W. This is considered to be caused by impurities contained therein or a reaction product with elements in the environment.

  On the other hand, in the comparative example, since the amount of the compound resulting from the decomposition of the above-described ammonium silicofluoride 81 was confirmed to be about 10 times that of Examples 1 and 2, it was clearly on the wafer W before analysis. It is thought that ammonium 81 was deposited.

  In addition, since the amount of the product is substantially the same between Example 1 and Example 2, the wafer W may be exposed to the air atmosphere after the ammonia treatment and before the heat treatment. I understood.

It is a top view which shows an example of the substrate processing apparatus of this invention. It is a longitudinal cross-sectional view which shows an example of the plasma processing apparatus used for the plasma processing of this invention. It is a longitudinal cross-sectional view which shows an example of the heating apparatus used for the heat processing of this invention. It is sectional drawing of the board | substrate which shows an example of the substrate processing method in the 1st Embodiment of this invention. It is sectional drawing of the board | substrate which shows an example of the substrate processing method in the 2nd Embodiment of this invention. It is sectional drawing of the board | substrate which shows an example of said board | substrate processing method. It is a top view which shows an example of the substrate processing apparatus in this invention. It is a longitudinal cross-sectional view which shows an example of the above-mentioned substrate processing apparatus. It is sectional drawing of the board | substrate used for the Example of this invention. It is a characteristic view which shows the result of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Substrate processing apparatus 13 1st transfer chamber 14 Load lock chamber 16 2nd transfer chamber 17 1st transfer means 18 2nd transfer means 21 Processing container 51 Plasma processing apparatus 54 Heating apparatus 73 Copper wiring 74 SiC film 76 Organic Film 80 Deposit 81 Ammonium silicofluoride

Claims (14)

In order to remove the etching stop film containing silicon and carbon formed on the surface of the metal wiring at the bottom of the concave portion of the film on the substrate formed by etching, the substrate is treated with fluorine in a processing container. A step (a) of exposing a processing gas containing plasma to plasma generated by plasma;
In order to remove the organic film formed as a by-product on the metal wiring in the step (a), the processing gas containing nitrogen and hydrogen is converted into plasma in the processing vessel in which the step (a) is performed. A step (b) in which ammonium silicofluoride is produced on the substrate by exposure to the plasma produced in the step;
Then, before the substrate is placed in a clean room atmosphere, the substrate is heated in the processing container to a temperature equal to or higher than the decomposition temperature of the ammonium silicofluoride.   The substrate processing method according to claim 1, wherein the step of heating the substrate is performed in a processing container different from the processing container in which the steps (a) and (b) are performed.   The substrate processing method according to claim 1, wherein the processing gas containing fluorine is a gas containing fluorine and carbon.   The substrate processing method according to claim 1, wherein the processing gas containing nitrogen and hydrogen is ammonia gas. A sacrificial film made of an organic film exposed on the surface of the film is provided on the substrate on which the step (a) is performed,
The substrate processing method according to claim 1, wherein the sacrificial film is removed together with the organic film formed as the by-product by performing the step (b). Plasma treatment with a processing gas containing fluorine is performed in a processing container on the substrate in which the film containing silicon and carbon is exposed in the recess, thereby etching the film containing silicon and carbon and silicon in the recess A step (a) in which a CF-based deposit containing
Next, a step (b) of removing the deposits in the concave portion and forming ammonium silicofluoride on the inner surface of the concave portion by plasma of a processing gas containing nitrogen and hydrogen with respect to the substrate in the processing container. ,
Then, before the substrate is placed in a clean room atmosphere, the substrate is heated to a temperature higher than the decomposition temperature of ammonium silicofluoride in the processing container and removed (c).   The substrate processing method according to claim 6, wherein the processing gas containing nitrogen and hydrogen is ammonia gas.   The substrate processing method according to claim 6, wherein the film containing silicon and carbon is a SiC film or a SiCN film.   The substrate processing method according to claim 6, wherein the step (c) is performed in a processing container different from the processing container in which the step (a) is performed.   The substrate processing method according to claim 6, wherein the step (c) and the step (b) are performed in the same processing container. A storage medium storing a computer program used on a substrate processing apparatus for processing a substrate in a processing container and operating on a computer,
A storage medium characterized in that the computer program includes steps so as to implement the substrate processing method according to any one of claims 1 to 10. A substrate processing apparatus for processing a substrate in which a film containing silicon and carbon is exposed in a recess,
A step of performing plasma treatment with a treatment gas containing fluorine on the substrate in a treatment container, thereby etching the film containing silicon and carbon and generating a CF-based deposit containing silicon in the recess. (A) and
Next, a step (b) of removing the deposits in the concave portion and forming ammonium silicofluoride on the inner surface of the concave portion by plasma of a processing gas containing nitrogen and hydrogen with respect to the substrate in the processing container. ,
Next, before the substrate is placed in a clean room atmosphere , a control signal is output so as to perform the step (c) of removing the substrate by heating it to a temperature higher than the decomposition temperature of ammonium silicofluoride in the processing container. A substrate processing apparatus comprising a section.   The substrate processing apparatus according to claim 12, further comprising a first processing container for performing the step (a).   The substrate processing apparatus according to claim 13, further comprising a second processing container provided separately from the first processing container and performing the step (c).

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