Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—After-treatment
  • H01L21/311—Etching the insulating layers by chemical or physical means
  • H01L21/31105—Etching inorganic layers
  • H01L21/31111—Etching inorganic layers by chemical means
  • H01L21/31116—Etching inorganic layers by chemical means by dry-etching

Definitions

• the present invention relates to an etching method and a recording medium.
• a method of dry etching a silicon oxide film existing on the surface of a semiconductor wafer (hereinafter referred to as “wafer”) without using plasma is known.
• a powerful dry etching method is that the inside of the chamber in which the wafer is housed is brought to a low pressure state close to a vacuum state, and the wafer is temperature-controlled to a predetermined temperature, while hydrogen fluoride gas (HF) and ammonia gas are placed in the chamber. (NH) and
• 3) a process of supplying a mixed gas to alter the silicon oxide film to produce a reaction product, and a heating process to heat and vaporize (sublimate) the reaction product.
• the silicon oxide film is etched by transforming into a reaction product and removing it by heating.
• silicon oxide films having different generation causes, film forming methods, and the like.
• CVD type oxide film thermal acid film, BPSG, etc.
• CVD reaction with CVD (Chemical Vapor Deposition) equipment the reaction of the mixed gas selectively and actively takes place in the alteration process of the etching method is a natural oxide film or a chemical oxide film, and the same silicon oxide film. Even if it is a film, it is not actively applied to CVD-based oxide films.
• this dry etching method efficiently removes only the natural oxide film and the chemical oxide film while suppressing the etching of other structures having a high etching selection ratio with respect to the natural oxide film or the chemical oxide film. can do. Therefore, this dry etching method is suitable for a process of removing a natural oxide film or a chemical oxide film adhering to a wafer, for example, as a pretreatment before performing a film forming process on a wafer.
• Patent Document 1 US Patent Application Publication No. 2004Z0182417
• Patent Document 2 US Patent Application Publication No. 2004Z0184792
• Patent Document 3 Japanese Patent Laid-Open No. 2005-39185
• the alteration of the oxide film is characterized by the fact that when the surface force of the oxide film progresses to a certain depth, it becomes saturated (saturation) and does not progress further. is there. That is, there is a limit to the amount of etching that can be performed by one alteration process and heating process. For this reason, in order to obtain the etching amount required for the CVD-based oxide film, it is necessary to repeat the alteration process and the heating process a plurality of times, which is inefficient.
• the present invention has been made in view of the above points, and provides an etching method capable of efficiently dry-etching various silicon oxide films according to the type of each silicon oxide film.
• the purpose is to do.
• a method for etching a silicon oxide film wherein a mixed gas containing hydrogen fluoride gas and ammonia gas is formed on the surface of the silicon oxide film. And a chemical reaction between the silicon oxide film and the mixed gas to alter the silicon oxide film to produce a reaction product, and a heating process to heat and remove the reaction product. And in the alteration step, the silicon oxide film seeds
• the etching method is characterized by adjusting the temperature of the silicon oxide film and the partial pressure of the hydrogen fluoride gas in the mixed gas according to the kind. According to the etching method, the depth at which the reaction product becomes saturated in the alteration process can be adjusted according to the type of the silicon oxide film.
• the process of generating a reaction product by altering the silicon oxide film present on the surface of the substrate is, for example, a COR (Chemical Oxide Removal) process (chemical oxide removal process).
• COR processing a gas containing a halogen element such as hydrogen fluoride gas (HF) and a basic gas such as ammonia gas (NH 2) are supplied to the substrate as a processing gas.
• a gas containing a halogen element such as hydrogen fluoride gas (HF) and a basic gas such as ammonia gas (NH 2) are supplied to the substrate as a processing gas.
• HF hydrogen fluoride gas
• NH 2 ammonia gas
• the silicon oxide film on the top and the gas molecules of the processing gas are chemically reacted to generate a reaction product.
• a reaction product containing mainly fluorosilicate ammonium ((NH) SiF) and moisture (H 2 O) is produced. Also anti
• the treatment for removing the reaction product by heating is, for example, a PHT (Post Heat Treatment) treatment.
• the PHT process is a process in which the wafer after the COR process is heated to vaporize (sublimate) reaction products such as fluorinated ammonium.
• the temperature of the silicon oxide film may be 35 ° C or higher.
• the partial pressure of the hydrogen fluoride gas in the mixed gas may be 15 m Torr (about 2. OOPa) or more. Furthermore, in the alteration step, the partial pressure of the ammonia gas in the mixed gas may be smaller than the partial pressure of the hydrogen fluoride gas.
• the etching amount of the reaction product may be 30 nanometers or more.
• the silicon oxide film may be formed by a CVD method.
• the silicon oxide film may be a BPSG film or a silicon oxide film formed using a bias high density plasma CVD method.
• a recording medium on which a program that can be executed by a control unit of a processing system is recorded, and the program is executed by the control unit, whereby the processing is performed.
• a recording medium characterized in that the system performs any one of the above etching methods.
• various silicon oxide films can be used in accordance with the type of each silicon oxide film. Dry etching can be performed efficiently. Since plasma is not used, there is no worry of causing charge-up damage due to plasma on wafers. There is no worry of adversely affecting other parts other than the etching target.
• FIG. 1 is a schematic longitudinal sectional view showing the structure of a wafer surface before etching a BPSG film.
• FIG. 2 is a schematic plan view of the processing system.
• FIG. 3 is an explanatory diagram showing a configuration of a PHT processing apparatus.
• FIG. 4 is an explanatory diagram showing a configuration of a COR processing device.
• FIG. 5 is a schematic longitudinal sectional view showing a state of a wafer after COR processing.
• FIG. 6 is a schematic longitudinal sectional view showing a state of a wafer after PHT processing.
• FIG. 7 is a schematic longitudinal sectional view showing a state of a wafer after a film forming process.
• FIG. 8 is a schematic plan view of a processing system according to another embodiment.
• FIG. 9 is a schematic longitudinal sectional view showing the structure of the surface of a wafer that is used in another embodiment.
• FIG. 10 is a graph showing the experimental results of Experiment 1.
• FIG. 11 is a graph showing the experimental results of Experiment 2.
• FIG. 12 is a table showing experimental conditions and results of Experiment 3.
• FIG. 13 is a graph showing the experimental results of Experiment 3.
• FIG. 1 is a schematic cross-sectional view of a wafer W during a manufacturing process in which a DRAM (Dynamic Random Access Memory) is formed as a semiconductor device, and shows a part of the surface of the wafer W (device formation surface).
• Wafer W is, for example, a thin silicon wafer formed in a substantially disk shape, and a BPSG (Boron-Doped Phospho Silicate Glass) film 101, which is an insulating film, is formed on the surface of Si (silicon) layer 100.
• the BPSG film 101 is a silicon oxide film (silicon dioxide (SiO 2)) containing boron (B) and phosphorus (P). This
• the BPSG film 101 is a CVD-based silicon oxide film formed on the surface of the wafer W by a thermal CV D method in a CVD (Chemical Vapor Deposition) apparatus or the like.
• a gate portion G force having a gate electrode is provided side by side.
• Each gate portion G includes a gate electrode 102, a hard mask layer 103, and side wall portions (sidewalls) 104.
• the gate electrode 102 is, for example, a Poly—Si (polycrystalline silicon) layer.
• the gate electrode 102 is formed side by side on the upper surface of the BPSG film 102.
• a WSi (tungsten silicide) layer 105 is formed on the upper surface of each poly-Si layer (gate electrode 102).
• the hard mask layer 103 has an insulating force such as SiN (silicon nitride).
• the hard mask layer 103 is formed on the upper surface of each WSi layer 105.
• the side wall portion 104 is an insulator such as a SiN film.
• the side wall portion 104 is formed so as to cover both side surfaces of each poly-Si layer (gate electrode 102), WSi layer 105, and hard mask layer 103, respectively.
• the lower end portion of the SiN film (side wall portion 104) is formed up to a position in contact with the upper surface of the BPSG film 101.
• an HDP-SiO film (silicon oxide film) 110 is formed above the BPSG film 101 so as to cover the entire BPSG film 101 and each gate part G.
• This HDP—SiO film (silicon oxide film) 110 is formed above the BPSG film 101 so as to cover the entire BPSG film 101 and each gate part G.
• the O film 110 is formed by using a bias high density plasma CVD method (HDP—CVD method).
• the HDP-SiO film 110 and the BPSG film 101 are both CVD oxide films.
• the DP-SiO film 110 is a hard material having a higher density than the BPSG film 101.
• a film is not yet formed on the surface of the P-SiO film 110 and is exposed.
• a contact hole H is formed between the SiN films (between the side wall portions 104).
• the contact hole H penetrates from the upper surface of the HDP-SiO film 110 to the surface of the BPSG film 101.
• the mask layer 103 is formed by selective (anisotropic) etching.
• the processing system 1 shown in FIG. 2 includes a loading / unloading section 2 for loading / unloading the wafer W into / from the processing system 1, two load lock chambers 3 provided adjacent to the loading / unloading section 2, and each load lock chamber 3 PHT treatment equipment 4 that performs a PHT (Post Heat Treatment) process as a heating process, and COR (Chemical Oxide Removal) as an alteration process that is provided adjacent to each PHT treatment equipment 4 It has a COR processing device 5 that performs processing steps, and a control computer 8 as a control unit that gives control commands to each part of the processing system 1.
• the PHT processing device 4 and the COR processing device 5 respectively connected to the load port chambers 3 are provided with the load port chamber 3 side forces arranged in a straight line in this order.
• the loading / unloading unit 2 has a transfer chamber 12 in which a first wafer transfer mechanism 11 for transferring, for example, a substantially disk-shaped wafer W is provided.
• the wafer transfer mechanism 11 has two transfer arms lla and lib that hold the wafer W substantially horizontally.
• an orienter 14 is installed to rotate the wafer W and optically determine the amount of eccentricity for alignment.
• the wafer W is held by the transfer arms lla and lib, and is rotated and straightly moved and moved up and down substantially in a horizontal plane by driving the wafer transfer device 11. It is transported to a desired position. That is, the transport arm l la and l ib are moved back and forth with respect to the carrier 13 a, the orienter 14, and the load lock chamber 3 on the mounting table 10, so that the wafer W is carried in and out.
• Each load lock chamber 3 is connected to the transfer chamber 12 via a gate valve 16.
• a second wafer transfer mechanism 17 for transferring the wafer W is provided in each load lock chamber 3.
• the wafer transfer mechanism 17 has a transfer arm 17a that holds the wafer W substantially horizontally.
• the inside of the load lock chamber 3 can be evacuated.
• the wafer W is held by the transfer arm 17a, and is transferred by rotating and moving in a substantially horizontal plane and moving up and down by driving the wafer transfer mechanism 17. . Then, the wafer W is carried into and out of the PHT processing apparatus 4 by moving the transfer arm 17a forward and backward with respect to the PHT processing apparatuses 4 connected in series to each load lock chamber 3. Further, the wafer W is carried into and out of the COR processing device 5 by moving the transfer arm 17a forward and backward with respect to the COR processing device 5 via each PHT processing device 4.
• the PHT processing apparatus 4 includes a sealed processing chamber (processing space) 21 in which the wafer W is stored. Although not shown, a loading / unloading port for loading / unloading the wafer W into / from the processing chamber 21 is provided, and a gate valve 22 for opening / closing the loading / unloading port is provided.
• the processing chamber 21 is connected to the load lock chamber 3 through a gate valve 22.
• a mounting table 23 is provided in the processing chamber 21 of the PHT processing apparatus 4 for mounting the wafer W substantially horizontally.
• nitrogen gas (N) in the processing chamber 21 is nitrogen gas (N) in the processing chamber 21
• a supply mechanism 26 having a supply path 25 for heating and supplying the second inert gas and an exhaust mechanism 28 having an exhaust path 27 for exhausting the processing chamber 21 are provided.
• the supply path 25 is connected to a nitrogen gas supply source 30.
• the supply path 25 is provided with a flow rate adjusting valve 31 that can open and close the supply path 25 and adjust the supply flow rate of nitrogen gas.
• the exhaust passage 27 is provided with an on-off valve 32 and an exhaust pump 33 for forced exhaust.
• the gate valve 22, the flow rate adjustment valve 31, the on-off valve 32, the exhaust pump of the PHT treatment device 4 The operation of each part such as 33 is controlled by the control command of the control computer 8. That is, the supply of nitrogen gas by the supply mechanism 26 and the exhaust by the exhaust mechanism 28 are controlled by the control computer 8.
• the COR processing apparatus 5 includes a chamber 40 having a sealed structure.
• the inside of the chamber 40 is a processing chamber (processing space) 41 in which the wafer W is stored.
• a mounting table 42 for mounting the wafer W in a substantially horizontal state is provided inside the chamber 40.
• the COR processing apparatus 5 is provided with a supply mechanism 43 for supplying gas to the processing chamber 41 and an exhaust mechanism 44 for exhausting the inside of the processing chamber 41.
• a loading / unloading port 53 for loading / unloading the wafer W into / from the processing chamber 41 is provided, and a gate valve 54 for opening / closing the loading / unloading port 53 is provided.
• the processing chamber 41 is connected to the processing chamber 21 through a gate valve 54.
• a shower head 52 having a plurality of discharge ports for discharging process gas is provided on the ceiling of the chamber 40.
• the mounting table 42 has a substantially circular shape in plan view, and is fixed to the bottom of the chamber 40. Inside the mounting table 42, a temperature controller 55 that adjusts the temperature of the mounting table 42 is provided.
• the temperature controller 55 includes, for example, a conduit through which a temperature adjusting liquid (for example, water) is circulated. By exchanging heat with the liquid flowing in the powerful pipeline, the temperature of the upper surface of the mounting table 42 is adjusted, and further, heat exchange is performed between the mounting table 42 and the wafer W on the mounting table 42. As a result, the temperature of the wafer W is adjusted.
• the temperature controller 55 is not limited to a powerful one, and may be, for example, an electric heater that heats the mounting table 42 and the wafer W using resistance heat.
• the supply mechanism 43 supplies ammonia gas (NH 3) to the above-described shower head 52, hydrogen fluoride gas supply path 61 for supplying hydrogen fluoride gas (HF) to the process chamber 41, and process chamber 41.
• NH 3 ammonia gas
• HF hydrogen fluoride gas
• Nitrogen gas supply path 63 for supplying argon gas (Ar) as an inert gas to the ammonia gas supply path 62 and processing chamber 41, and nitrogen gas (N) for supplying nitrogen gas (N) as an inert gas to the processing chamber 41
• An elementary gas supply path 64 is provided.
• the hydrogen fluoride gas supply path 61, the ammonia gas supply path 62, the argon gas supply path 63, and the nitrogen gas supply path 64 are connected to the shower head 52.
• the treatment chamber 41 is supplied with hydrogen fluoride gas, ammonia gas, and alcohol through a shower head 52. Gon gas and nitrogen gas are diffused and discharged!
• the hydrogen fluoride gas supply path 61 is connected to a hydrogen fluoride gas supply source 71.
• the hydrogen fluoride gas supply path 61 is provided with a flow rate adjusting valve 72 capable of opening / closing the hydrogen fluoride gas supply path 61 and adjusting the supply flow rate of the hydrogen fluoride gas.
• the ammonia gas supply path 62 is connected to an ammonia gas supply source 73.
• the ammonia gas supply path 62 is provided with a flow rate adjusting valve 74 capable of opening and closing the ammonia gas supply path 62 and adjusting the supply flow rate of the ammonia gas.
• the argon gas supply path 63 is connected to an argon gas supply source 75.
• the argon gas supply path 63 is provided with a flow rate adjusting valve 76 that can open and close the argon gas supply path 63 and adjust the supply flow rate of the argon gas.
• the nitrogen gas supply path 64 is connected to a nitrogen gas supply source 77.
• the nitrogen gas supply path 64 is provided with a flow rate adjusting valve 78 capable of opening / closing the nitrogen gas supply path 64 and adjusting the supply flow rate of the nitrogen gas.
• the exhaust mechanism 44 includes an exhaust passage 85 having an on-off valve 82 and an exhaust pump 83 for performing forced exhaust.
• the upstream end of the exhaust passage 85 is opened at the bottom of the chamber 40.
• each part of the COR processing device 5 such as the gate valve 54, the temperature controller 55, the flow rate adjustment valves 72, 74, 7 6, 78, the on-off valve 72, the exhaust pump 83, is controlled by the control computer 8.
• Each is controlled by an instruction. That is, supply of hydrogen fluoride gas, ammonia gas, argon gas, nitrogen gas by the supply mechanism 43, exhaust by the exhaust mechanism 44, temperature adjustment by the temperature controller 55, and the like are controlled by the control computer 8.
• Each functional element of the processing system 1 is connected to a control computer 8 that automatically controls the operation of the entire processing system 1 via a signal line.
• the functional elements include, for example, the wafer transfer mechanism 11, the wafer transfer mechanism 17, the gate valve 22 of the PHT processing device 4, the flow rate adjusting valve 31, the exhaust pump 33, the gate valve 54 of the COR processing device 5, the temperature described above, and the like. It means all the elements that operate to achieve a given process condition, such as the regulator 55, flow control valves 72, 74, 76, 78, on-off valve 72, exhaust pump 83, and so on.
• the control computer 8 is typically a general-purpose computer that can realize any function depending on the software to be executed.
• the control computer 8 includes a calculation unit 8a having a CPU (central processing unit). And an input / output unit 8b connected to the calculation unit 8a, and a recording medium 8c inserted in the input / output unit 8b and storing control software.
• the recording medium 8c stores control software (program) that is executed by the control computer 8 to cause the processing system 1 to perform a predetermined substrate processing method to be described later.
• the control computer 8 realizes various process conditions (for example, pressure in the processing chamber 41) defined for each functional element of the processing system 1 by a predetermined process recipe. To control. That is, as will be described in detail later, a control command is provided that realizes an etching method in which the COR processing step in the COR processing device 5 and the PHT processing step in the PHT processing device 4 are performed in this order.
• the recording medium 8c is fixedly provided in the control computer 8, or is detachably attached to a reading device (not shown) provided in the control computer 8 and can be read by the reading device. There may be.
• the recording medium 8c is a hard disk drive that has been installed with control software force S by the service person of the manufacturer of the processing system 1.
• the recording medium 8c is a removable disk such as a CD-ROM or DVD-ROM in which control software is written. Such a removable disk is read by an optical reading device (not shown) provided in the control computer 8.
• the recording medium 8c may be in any format of RAM (.random access memory) XiiROM i, read only memory). Further, the recording medium 8c may be a cassette type ROM.
• any medium known in the technical field of computers can be used as the recording medium 8c.
• control software may be stored in a management computer that controls the control computer 8 of each processing system 1 in an integrated manner.
• each processing system 1 is operated by a management computer via a communication line and executes a predetermined process.
• a contact hole H is formed in the HDP-SiO film 110.
• the resulting woofer W power is stored in the carrier 13 a and is transported to the processing system 1.
• a carrier 13 a in which a plurality of wafers W are stored is mounted on the mounting table 13.
• One wafer W is taken out from the carrier 13 a by the wafer transfer mechanism 11 and is loaded into the load lock chamber 3.
• the load lock chamber 3 is sealed and decompressed. Thereafter, the gate valves 22 and 54 are opened, and the load lock chamber 3 and the processing chamber 21 of the PHT processing apparatus 4 and the processing chamber 41 of the COR processing apparatus 5 that are decompressed with respect to the atmospheric pressure are communicated with each other.
• the wafer W is unloaded from the load lock chamber 3 by the wafer transfer mechanism 17 and is moved straight so as to pass through the loading / unloading port (not shown) of the processing chamber 21, the processing chamber 21, and the loading / unloading port 53 in this order. Carried into chamber 41.
• the wafer W is transferred from the transfer arm 17 a of the wafer transfer mechanism 17 to the mounting table 42 with the device formation surface as the upper surface.
• the transfer arm 17a is withdrawn from the processing chamber 41.
• the loading / unloading port 53 is closed, and the processing chamber 41 is sealed. Then, the COR processing process is started.
• ammonia gas, argon gas, and nitrogen gas are supplied to the processing chamber 41 from an ammonia gas supply path 62, an argon gas supply path 63, and a nitrogen gas supply path 64, respectively. Further, the pressure in the processing chamber 41 is set to a pressure lower than the atmospheric pressure. Further, the temperature of the wafer W on the mounting table 42 is adjusted to a predetermined target value (for example, about 35 ° C.) by the temperature controller 55.
• a predetermined target value for example, about 35 ° C.
• hydrogen fluoride gas is supplied from the hydrogen fluoride gas supply path 61 to the processing chamber 41.
• ammonia gas is supplied to the processing chamber 41 in advance, by supplying hydrogen fluoride gas, the atmosphere of the processing chamber 41 also has a mixed gas force including hydrogen fluoride gas and ammonia gas. A processing atmosphere. In this way, the mixed gas is supplied to the surface of the wafer and the wafer W in the processing chamber 41, whereby the COR process is performed on the wafer W.
• the BPSG film 101 existing at the bottom of the contact hole H on the surface of the wafer W reacts with the molecules of hydrogen fluoride gas and ammonia gas in the mixed gas.
• the reaction product 101 ′ is transformed (see FIG. 5).
• ammonia of fluorinated acid is generated. Since this chemical reaction proceeds isotropically, the chemical reaction starts from the bottom of the contact hole H. It progresses to the upper surface of the Si layer and also proceeds in the lateral direction from directly below the contact hole H above the Si layer.
• the pressure of the mixed gas (processing atmosphere) in the processing chamber 41 is reduced from the atmospheric pressure by adjusting the supply flow rate of each processing gas, the supply flow rate of the inert gas, the exhaust flow rate, and the like. Adjust the pressure so that it is maintained at a constant pressure (for example, about 80 mTorr (about 10.7 Pa)).
• the partial pressure of hydrogen fluoride gas in the mixed gas may be adjusted to be about 15 mTorr (about 2. OOPa) or more.
• the temperature of the wafer W that is, the temperature of the portion where the chemical reaction occurs in the BPSG film 101 (the temperature of the portion where the BPSG film 101 and the mixed gas are in contact (that is, the bottom of the contact hole H)).
• the temperature of the wafer W May be maintained at a constant temperature of, for example, about 35 ° C or higher.
• the chemical reaction is promoted, the generation rate of the reaction product 101 ′ is increased, and the layer of the reaction product 101 ′ can be rapidly formed.
• the depth at which the chemical reaction becomes saturated (the distance between the surface force of the BPSG film 101 and the position where the chemical reaction stops) can be made sufficiently deep.
• the chemical reaction is sufficiently performed without stopping.
• the sublimation point of the fluoroalkylammonium in the reaction product 101 is about 100 ° C, and when the temperature of the wafer W is set to 100 ° C or higher, the reaction product 101 'is generated satisfactorily. There is a risk of being lost. Therefore, it is preferable that the temperature of the wafer W is less than about 100 ° C.
• the depth at which the chemical reaction becomes saturated depends on the type of silicon oxide film (BPSG film 101 in the present embodiment), the temperature of the silicon oxide film (or silicon oxide film). The temperature of the gas mixture in contact with the gas) and the partial pressure of the hydrogen fluoride gas in the gas mixture. That is, by adjusting the temperature of the silicon oxide film and the partial pressure of the hydrogen fluoride gas according to the type of silicon oxide film, the depth at which the chemical reaction becomes saturated and the reaction product The production amount of the composition 101 ′ can be controlled, and consequently, the etching amount after the PHT treatment, which will be described in detail later, can be controlled.
• the depth at which the chemical reaction becomes saturated that is, the etching amount, in the case of the BPSG film 101, the temperature of the BPSG film 101 is 35 ° C or more, and the partial pressure of the hydrogen fluoride gas is about 15 mTorr (about 2.OOPa ) By adjusting above, it is possible to make it more than about 30nm (nanometer).
• the temperature of the wafer W is about 30 ° C or less. It was.
• the partial pressure of hydrogen fluoride gas in the mixed gas was increased, the chemical reaction proceeded only at a certain depth. Therefore, it is considered that there is a limit to the etching amount by the COR process, and the etching amount that can be reliably etched by one COR process is, for example, less than about 30 nm in the BPSG film 101.
• the temperature of the wafer W is set to 35 ° C or higher, which is higher than the conventional temperature, and the partial pressure of the hydrogen fluoride gas in the mixed gas is increased to about 15 mTorr (about 2 By increasing it to more than (OOPa), the depth at which the chemical reaction becomes saturated can be increased, and a sufficient amount of etching can be performed even with a single COR process.
• the HDP—SiO film 110 formed above the BPSG film 101 By the way, in the COR process, the HDP—SiO film 110 formed above the BPSG film 101.
• the HD P—SiO film 110 may be altered by the COR process. Modification of this HDP-SiO film 110
• the partial pressure of ammonia gas in the mixed gas should be smaller than the partial pressure of hydrogen fluoride gas. That is, the ammonia gas supply flow rate is preferably smaller than the hydrogen fluoride gas supply flow rate. Then, while the chemical reaction is actively progressing in the BPSG film 101, the HDP-SiO film 110 can prevent the chemical reaction from progressing.
• the BPSG film 101 is selectively suppressed while suppressing the alteration of the HDP-SiO film 110 and the like.
• the reaction rate of the chemical reaction, the amount of reaction product generated, etc. can be made different from each other, and the etching amount after the PHT treatment, which will be described in detail later, is different from each other. Can be.
• the chemical reaction when the partial pressure of ammonia gas is smaller than the partial pressure of hydrogen fluoride gas is a reaction rate-determining method in which the production rate of the reaction product 101 ′ is determined by the chemical reaction between the BPSG film 101 and the mixed gas. It is thought that this is a feed-limited reaction in which the production rate of the reaction product 101 ′ is determined by the supply flow rate of the hydrogen fluoride gas.
• the process chamber 41 is forcibly exhausted and depressurized. As a result, hydrogen fluoride gas and ammonia gas are discharged from the processing chamber 41. It is forcibly discharged.
• the loading / unloading port 53 is opened, and the wafer W is unloaded from the processing chamber 41 by the wafer transfer mechanism 17 and loaded into the processing chamber 21 of the PHT processing apparatus 4. As described above, the COR processing step is completed.
• the wafer W is placed in the processing chamber 21 with the surface as the upper surface.
• the transfer arm 17a is withdrawn from the processing chamber 21, the processing chamber 21 is sealed, and the PHT processing step is started.
• a high-temperature heated gas is supplied into the processing chamber 21 and the temperature in the processing chamber 21 is raised.
• the reaction product 101 ′ generated by the COR treatment is heated and vaporized, and passes from the lower part of the contact hole H to the inside of the contact hole H, and then the outside of the HDP-SiO film.
• the BPSG film 101 can be etched to a predetermined depth.
• the HDP-SiO film 110 which is a silicon oxide film, undergoes a slight chemical reaction with the mixed gas.
• the surface of the HDP-SiO film 110 is altered to produce a small amount of reaction product. Only
• the BPSG film 101 and the HDP-SiO film 110 are identical to each other.
• reaction product 101 ′ is generated in the BPSG film 101. Therefore, the reaction product is removed from the HDP-SiO film 110 by the PHT treatment.
• the etching amount of the HDP-SiO film 110 is the same as the etching amount of the BPSG film 110.
• the PHT of each silicon oxide film (BPSG film 101, HDP-SiO film 110) is adjusted by adjusting the partial pressure of ammonia gas in the mixed gas to be smaller than the partial pressure of hydrogen fluoride gas in the COR process. Reduce the amount of etching after processing.
• the etching selectivity of the BPSG film 101 is set to the HDP-SiO film 110 or the like. It can be higher than other structures.
• the supply of the heated gas is stopped, and the loading / unloading port of the PHT treatment device 4 is opened. Thereafter, the wafer W is unloaded from the processing chamber 21 by the wafer transfer mechanism 17 and returned to the load lock chamber 3. Thus, the PHT treatment process in the PHT treatment apparatus 4 is completed.
• the load lock chamber 3 and the transfer chamber 12 are communicated with each other. Then, the wafer transport mechanism 11 unloads the wafer W from the load lock chamber 3 and returns it to the carrier 13a on the mounting table 13. As described above, a series of etching steps in the processing system 1 is completed.
• the wafer W after the etching process is completed in the processing system 1 is carried into a film forming apparatus such as a CVD apparatus in another processing system, and is formed on the wafer W by, for example, a CVD method or the like.
• Film processing is performed.
• film formation is performed so as to fill the contact hole H and the space H ′ as shown in FIG.
• the capacitor C is formed in the contact hole H and the space H.
• the capacitor C is formed so as to penetrate the HDP-SiO film 110 and the BPSG film 101 between the gate portions G.
• the lower end of the capacitor C is connected to the upper surface of the Si layer 100 in the space H.
• the BPSG film 101 can be efficiently dry etched without using plasma. Therefore, there is no fear of adversely affecting other structures (films, layers, etc.) other than the BPSG film 101 formed on the wafer W, such as charge-up damage caused by plasma. Also, by adjusting the partial pressure of hydrogen fluoride gas and the temperature of the BPSG film 101, the speed of the chemical reaction with respect to the BPSG film 101 in the COR processing process can be improved, and the chemical reaction can be performed in the COR processing process. The depth of saturation can be made sufficiently deep. Therefore, the throughput of the COR processing step can be improved and the etching amount of the BPSG film 101 can be improved. A sufficient etching amount can be obtained at one time without repeating the COR processing step and the PHT processing step multiple times.
• the type of gas supplied to the processing chamber 41 in addition to hydrogen fluoride gas and ammonia gas is not limited to the combinations shown in the above embodiments.
• the inert gas supplied to the processing chamber 41 may be only argon gas.
• the inert gas may be any other inert gas such as helium gas (He) or xenon gas (Xe), or argon gas, nitrogen gas, helium gas, xenon. It may be a mixture of two or more gases.
• the structure of the processing system 1 is not limited to that shown in the above embodiment.
• a processing system including a film forming apparatus may be used.
• a common transfer chamber 92 having a wafer transfer mechanism 91 is connected to the transfer chamber 12 via a load lock chamber 93, and around the common transfer chamber 92,
• a configuration in which a COR processing device 95 and a PHT processing device 96, for example, a film forming device 97 such as a CVD device may be provided.
• the wafer transfer mechanism 91 allows the wafer W to be loaded into and unloaded from the load lock chamber 92, the COR processing apparatus 95, the PHT processing apparatus 96, and the film forming apparatus 97.
• the common transfer chamber 92 can be evacuated. That is, by setting the inside of the common transfer chamber 92 in a vacuum state, the wafer W unloaded from the PHT processing apparatus 96 can be loaded into the film forming apparatus 97 without being brought into contact with oxygen in the atmosphere. Therefore, it is possible to prevent the natural oxide film from adhering to the wafer W after the PHT treatment, and film formation (capacitor C formation) can be suitably performed.
• the silicon substrate that is a semiconductor wafer as a substrate having a silicon oxide film is not limited to a force substrate exemplified by W, but other types, for example, LCDs It may be a substrate glass, a CD substrate, a printed substrate, a ceramic substrate or the like.
• the structure of the substrate processed in the processing system 1 is not limited to that described in the above embodiment.
• the etching performed in the processing system 1 is not limited to the etching performed at the bottom of the contact hole H before the formation of the capacitor C as shown in the embodiment, and the present invention is not limited to various types. It can be applied to the etching method of the part.
• the silicon oxide film that is an object to be etched in the processing system 1 is also a BPSG film.
• other types of silicon oxide films such as HDP-SiO film may be used.
• the reaction product is saturated by adjusting the temperature of the silicon oxide film in the COR treatment process and the partial pressure of the hydrogen fluoride gas in the mixed gas according to the type of silicon oxide film. It is possible to control the depth of the state, the etching amount, and the like. In particular, it is performed on conventional natural oxide films and chemical oxide films! / It is possible to increase the depth at which the reaction product becomes saturated and to improve the etching amount, compared to the conventional etching method.
• the type of CVD method used for forming the CVD-based oxide film is not particularly limited.
• a thermal CVD method, an atmospheric pressure CVD method, a reduced pressure CVD method, a plasma CVD method, or the like may be used.
• the present invention relates to a silicon oxide film other than a CVD-based oxide film, for example, a natural oxide film, a chemical oxide film generated by chemical treatment in a resist removal process, etc., by a thermal oxidation method.
• the present invention can also be applied to etching of a silicon oxide film such as a formed thermal oxide film. Even in such silicon oxide films other than CVD-based oxide films, the etching amount can be increased or decreased by adjusting the partial pressure of hydrogen fluoride gas and the temperature of the silicon oxide film in the COR process. Togashi.
• the wafer W is left for a long time and is naturally left on the wafer W.
• the natural oxide film is sufficiently removed by performing the natural oxide film removal step by the etching method according to the present invention immediately before performing the next processing step. Can be removed. Therefore, it is possible to extend the waiting time until the natural oxide film removing step and the next processing step are performed after the previous processing step is completed. Therefore, the management time (Q-time) can be given flexibility.
• a natural oxide film and other silicon oxide films such as an interlayer insulating film are mixed on the wafer W, and only the natural oxide film is to be removed, COR In processing, the temperature of the wafer W should be lowered, or the partial pressure of the hydrogen fluoride gas in the mixed gas should be adjusted to be lower.
• the temperature of Ueno, W may be about 30 ° C or less
• the partial pressure of hydrogen fluoride gas in the mixed gas may be about 15 mTorr (about 2. OOPa) or less.
• the interlayer insulating film The natural oxide film can be efficiently altered while suppressing the alteration of other silicon oxide films. That is, the natural oxide film can be efficiently removed while suppressing damage to other structures.
• a structure shown in FIG. 9 is a case where a natural oxide film and other types of silicon oxide films are mixed on the wafer.
• a Si layer 150 is formed on the surface of a wafer W ′, and two gate portions G ′ having a gate electrode 151 are provided side by side on the upper surface thereof.
• Each gate part G ′ includes a gate electrode 151 (SiO layer) and a hard mask (HM) layer 152.
• SiN layer SiN layer
• side wall side wall 153
• SiO films 155 that are gate oxide films are formed on the upper surface of the Si layer 150, and the gate current is formed on the upper surface of each SiO film 155.
• HM layers are formed, and SiN layers (node mask (HM) layers 152) are formed on the upper surfaces of the respective Poly-Si layers (gate electrodes 151).
• PECVD plasma enhanced CVD
• a contact hole H is formed between the two gate parts G and (between the side wall part 153) so as to penetrate the PE—SiO film 157 and the BPSG film 156.
• a natural oxide film 160 is formed on the Si layer 150. That is, in this structure, three types of silicon oxide films, that is, a natural oxide film 160, a BPSG film 156, and a PE-SiO film 157 are mixed. This is, in this structure, three types of silicon oxide films, that is, a natural oxide film 160, a BPSG film 156, and a PE-SiO film 157 are mixed. This is, in this structure, three types of silicon oxide films, that is, a natural oxide film 160, a BPSG film 156, and a PE-SiO film 157 are mixed. This
• the BPSG film 156 and the PE-SiO film can be adjusted by appropriately adjusting the temperature of the wafer W and the partial pressure of the hydrogen fluoride gas in the mixed gas.
• the natural oxide film 160 can be selectively removed while suppressing 57 damage (CD shift). In addition, if the temperature of the wafer W and the partial pressure of the hydrogen fluoride gas in the mixed gas are adjusted according to the thickness of the natural oxide film 160, the natural oxide film formed thick by being left for a long period of time. Even 160 can be removed reliably. In addition, in the formation of a capacitor (film formation process) performed after removal of the natural oxide film 160 against the strong Ueno, W ′, contact holes By removing the natural oxide film 160 from the Si layer 150 exposed at the bottom of H, the lower end of the capacitor can be reliably connected to the Si layer 150.
• the present inventors conducted Experiment 1 for examining the conditions in the COR treatment process when etching a silicon oxide film.
• the object to be etched was a thermal oxide film (SiO 2) formed by a thermal oxidation method. Wafer W temperature is 25 ° C, 30 ° C, 35 ° C, 4
• the relationship between the partial pressure of hydrogen fluoride gas and the etching amount when it was set to o ° c was measured.
• the partial pressure of hydrogen fluoride gas was varied between 5 mTorr (about 0.667 Pa) and 35 mTorr (about 4.67 Pa).
• the result is shown in the graph of FIG.
• Fig. 10 when the temperature of wafer W is 25 ° C, the amount of etching is most powerful when the partial pressure of hydrogen fluoride gas is about 10 mTorr (about 1.33 Pa).
• the etching amount at that time was about 35 nm.
• the etching amount decreased as the partial pressure of hydrogen fluoride gas was lowered below about lOmTorr (about 1.33 Pa), and the etching amount decreased as the partial pressure was increased.
• the temperature of the wafer W was 30 ° C
• the amount of etching was highest when the partial pressure of the hydrogen fluoride gas was about 30 mTorr (about 4.00 Pa). It was about 40 ⁇ m.
• the wafer W temperature was 35 ° C, the etching amount increased as the partial pressure of the hydrogen fluoride gas was increased.
• the etching amount is small compared with the case of Ueno and W at 25 ° C and 30 ° C.
• the partial pressure of the film was about 25 mTorr (about 3.33 Pa) or more, the etching amount was larger than when the wafer W temperature was 25 ° C or 30 ° C.
• the etching amount was highest when the partial pressure of hydrogen fluoride gas was about 35 mTorr (about 4.67 Pa), and the etching amount at that time was about 50 nm.
• the etching amount increased as the partial pressure of the hydrogen fluoride gas was increased, as was the case when the temperature was 35 ° C.
• the partial pressure of hydrogen fluoride gas is about 30 mTorr (about 4.00 Pa)
• the etching amount is smaller than when the wafer W temperature is 25 ° C and 30 ° C.
• the pressure was about 30 mTorr (about 4.00 Pa) or higher
• the etching amount was higher than when the wafer W temperature was 25 ° C or 30 ° C.
• the etching amount was the highest This was when the partial pressure of hydrogen gas was about 35 mTorr (about 4.67 Pa), and the etching amount at that time was about 40 nm. From the above results, it was found that an etching amount of about 35 nm or more can be obtained.
• the present inventors conducted an experiment 2 for examining the conditions in the COR treatment process when etching the silicon oxide film.
• the object to be etched was a plasma CVD oxide film (SiO 2) formed by the plasma CVD method. And the temperature of wafer W is 2
• the relationship between the partial pressure of hydrogen fluoride gas and the etching amount at 5 ° C, 30 ° C, 35 ° C, and 40 ° C was measured.
• the partial pressure of hydrogen fluoride gas was changed between 5 mTorr (about 0.667 Pa) and 35 mTorr (about 4.67 Pa).
• the result is shown in the graph of FIG.
• Fig. 11 when the temperature of the wafer W was 25 ° C, the etching amount was the largest when the partial pressure of the hydrogen fluoride gas was applied to about 20 mTorr (about 2.67 Pa).
• the etching amount at that time was about 30 nm.
• the etching amount decreased as the partial pressure of hydrogen fluoride gas was lowered below about 20 mTorr (about 2.67 Pa), and the etching amount decreased as the partial pressure was increased.
• the wafer W temperature was 30 ° C
• the amount of etching was the highest when the partial pressure of hydrogen fluoride gas was about 30 mTorr (about 4. OOPa). It was about 35 nm.
• the temperature of the wafer W was 35 ° C, the etching amount increased as the partial pressure of the hydrogen gas increased.
• the etching amount is smaller than the case where the temperature of the wafer W is 25 ° C or 30 ° C until the partial pressure of the hydrogen fluoride gas is about 25 mTorr (about 3.33 Pa), the hydrogen fluoride gas When the partial pressure of 30 mTorr (about 4. OOPa) or higher, the etching amount was higher than when the wafer W temperature was 25 ° C and 30 ° C. The etching amount was the largest when the partial pressure of hydrogen fluoride gas was about 35 mTorr (about 4.67 Pa), and the etching amount at that time was about 40 nm or more.
• the amount of etching increased as the partial pressure of the hydrogen fluoride gas was increased, as was the case when the temperature was 35 ° C.
• the most effective etching amount was when the partial pressure of hydrogen fluoride gas was about 35 mTorr (about 4.67 Pa).
• the inventors of the present invention have proposed that the partial pressure of the hydrogen fluoride gas in the mixed gas in the COR process and the ammonia Experiment 3 was conducted to compare the etching amount for various materials when the partial pressure of the agas was changed.
• As the mixed gas a gas in which three types of hydrogen fluoride gas, ammonia gas, and argon gas were mixed was used. Each object was subjected to COR processing under the following four conditions A, B, C, and D (see Fig. 12), and then PHT processing. Then, the removal amount of the reaction product after the PHT treatment, that is, the etching amount was measured. Furthermore, the average value of etching amount, standard deviation, etc. were calculated.
• the total pressure of the mixed gas was 40 mTorr (about 5.33 Pa), and the partial pressure of hydrogen fluoride gas and the partial pressure of ammonia gas were 18 mTorr (about 2.40 Pa), respectively. That is, the partial pressure of hydrogen fluoride gas and the partial pressure of ammonia gas were set to the same value.
• the total pressure of the mixed gas was 80 mTorr (about 10.7 Pa), the partial pressure of hydrogen fluoride gas was 26.7 mTorr (about 3.56 Pa), and the partial pressure of ammonia gas was 15.2 mTorr (about 2.03 Pa). . That is, the partial pressure of ammonia gas was made lower than that of hydrogen fluoride gas.
• the total pressure of the mixed gas was 80 mTorr (about 10.7 Pa), and the partial pressure of hydrogen fluoride gas and the partial pressure of the ammonia gas were 26.7 mTorr (about 3.56 Pa), respectively. That is, the partial pressure of hydrogen fluoride gas is reduced by decreasing the partial pressure of argon gas and increasing the partial pressure of ammonia gas while keeping the pressure of the entire mixed gas and the partial pressure of hydrogen fluoride gas the same as in Condition B. The pressure and the partial pressure of ammonia gas were set to the same value.
• the total pressure of the mixed gas was 80 mTorr (about 10.7 Pa), the partial pressure of hydrogen fluoride gas was 32.9 mTorr (about 4.39 Pa), and the partial pressure of ammonia gas was 18.8 mTorr (about 2.51 Pa). . That is, the partial pressure of argon gas is decreased from condition B, the partial pressure of hydrogen fluoride gas and the partial pressure of ammonia gas are increased from condition B, respectively, and the partial pressure of ammonia gas is divided into the partial pressure of hydrogen fluoride gas. Less than the pressure.
• Conditions C and D were the etching amounts of the plasma CVD oxide film being relatively large, and Conditions B and D were the etching amounts of the thermal oxide film were relatively large.
• the ratio of the plasma CVD oxide film etching amount to the thermal oxide film etching amount was the least powerful in Condition B, and the plasma CVD oxide film etching amount relative to the thermal oxide film etching amount Condition C was the most powerful ratio.
• the state of the mixed gas in the COR process is set to condition B, that is, the partial pressure of ammonia gas is smaller than the partial pressure of hydrogen fluoride gas.
• the present invention can be applied to an etching method and a recording medium.

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