Patent Publication Number: US-2016240411-A1

Title: Multi-processing apparatus and method for manufacturing semiconductor device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2015-029910, filed on Feb. 18, 2015; the entire contents of which are incorporated herein by reference, 
     FIELD 
     Embodiments described herein relate generally to a multi-processing apparatus and a method for manufacturing a semiconductor device. 
     BACKGROUND 
     Highly-integrated semiconductor devices are manufactured by the use of a thin resist mask that is advantageous to form fine patterns. The thin resist is preferably subjected to plasma irradiation or electron beam irradiation in order to improve etching resistance property thereof, However, the resist mask may exhibit degradation of the property, when being exposed to the air just after the plasma irradiation or electron beam irradiation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG,  1  is a schematic view showing a multi-processing apparatus according to a first embodiment; 
         FIG. 2  is a flowchart showing a dry etching method according to the first embodiment; 
         FIGS. 3A to 3D  are schematic cross-sectional view showing a dry etching process according to the first embodiment; 
         FIG. 4  is a flowchart showing a dry etching method according to a second embodiment; and 
         FIGS. 5A to 5F  are schematic cross-sectional view showing a dry etching process according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment, a multi-processing apparatus includes an electron beam irradiation unit, a dry etching unit and a transfer unit. The transfer unit is connected to the electron beam irradiation unit and the dry etching unit, and is configured to transfer a wafer under a reduced-pressure atmosphere from the electron beam irradiation unit to the dry etching unit. 
     Embodiments will now be described with reference to the drawings, The same portions inside the drawings are marked with the same numerals; a detailed description is omitted as appropriate; and the different portions are described, The drawings are schematic or conceptual; and the relationships between the thicknesses and widths of portions, the proportions of sizes between portions, etc., are not necessarily the same as the actual values thereof, The dimensions and/or the proportions may be illustrated differently between the drawings, even in the case where the same portion is illustrated, 
     First Embodiment 
       FIG. 1  is a schematic view showing a multi-processing apparatus  1  according to a first embodiment, The multi-processing apparatus  1  includes an electron beam irradiation unit  10 , a dry etching unit  20 , and a plasma irradiation unit  30 . The multi-processing apparatus may sequentially carry out a plurality of manufacturing processes. The multi-processing apparatus  1  further includes a transferring unit  40 , and the electron beam irradiation unit  10 . The dry etching unit  20  and the plasma irradiation unit  30  are respectively connected to the transferring unit  40 . 
     The transferring unit  40  includes e.g. a carrying robot  41  and transfers a wafer  43  from one of the units to the other. The carrying robot  41  has a main body  45  and a robot arm  47 . The main body is capable of making a 360 turn, for example. Further, the transferring unit  40  transfers the wafer  43  between the respective units under reduced pressure. The interior of the transferring unit  40  is held at pressure of e.g. 10 Pa or less, Thereby, water may be evaporated from a resist mask formed on the surface of the wafer  43 . The oxygen concentration within the transferring unit  40  is held at 20 ppm or less. 
     The multi-processing apparatus  1  further includes a gate unit  50 , temperature adjustment units  60 ,  70 , and a control unit  80 . The wafer  43  is carried through the gate unit  50  from outside into the transferring unit  40  that is under reduced pressure, and the wafer  43  is carried out from the gate unit  50  after being processed. That is, the wafer  43  is carried in and carried out from the multi-processing apparatus  1  without breaking the reduced-pressure state of the transferring unit  40  by the use of the gate unit  50 . The temperature adjustment units  60 ,  70  hold the wafer  43  at a predetermined temperature. The temperature adjustment units  60 ,  70  makes it possible to omit wafer heating or cooling, for example, in the electron beam irradiation unit  10  and the plasma irradiation unit  30 . Thereby, the processing time in each unit may be shorter than that in an apparatus without a temperature adjustment unit. The control unit  80  sends commands to a controller of each unit and executes the multi-processing, as will be described later. 
     Next, a configuration of the multi-processing apparatus  1  will be explained in detail with reference to  FIG. 1 . 
     The electron beam irradiation unit  10  includes a wafer stage  11 , an electron-beam gun  13 , a voltage control device  15 , an isolation wall  17 , and a controller  19 . The controller  19  controls the electron-beam gun  13  to irradiate the wafer  43  placed on the wafer stage  11  with an electron beam, Further, the controller  19  controls the potential of the wafer stage  11  using the voltage control device  15 , 
     It is favorable that the wafer stage  11  is electrically connected to the wafer  43 . For example, the wafer stage  11  may include a connection conductor that is capable of being in contact with at least a part of the wafer  43 . Thereby, no potential difference is induced between the wafer stage  11  and the wafer  43 . 
     The wafer stage  11  may be at the ground potential or a potential set by the voltage control device  15 . The potential of the wafer stage  11  is set to e.g. −4000 V. Negative potential set to the wafer stage  11  makes it possible to monitor the secondary electrons emitted by electron beam irradiation. 
     Further, the negative potential induces a decelerating electric field for incident electrons toward the wafer stage  11  and an accelerating electric field for electrons emitted therefrom. 
     Thus, the negative potential may reduce the influence of charges in the wafer  43 . When the influence of charges in the wafer  43  is small, the wafer stage  11  may be set to have positive potential for accelerating the incident electrons. Furthermore, the wafer stage  11  contains at least one of a heater and a cooling element, and holds the wafer  43  at a predetermined temperature. For example, the wafer temperature is held at an arbitrary temperature within a temperature range from −40° C. to 290° C. The electron-beam gun  13  includes an electron beam source of e.g. a hot cathode, a photocathode, a field emission cathode, or the like. The electron beam source may be preferably selected depending on the area and the dose amount of electron beam irradiation. For example, a hot cathode of lanthanum boride (LaB 6 ) may be selected. 
     The isolation wall  17  electrically isolates the electron beam irradiation unit  10  from the transferring unit  40  and other units, That is, the isolation wall  17  may block the electrical noise from other units to achieve a stable operation of the electron-beam gun  13 . The isolation wall  17  is a connecting body made of e.g. a dielectric material, which is provided between the electron beam irradiation unit and the transferring unit  40 . Further, the isolation wall  17  includes a gate valve between the electron beam irradiation unit  10  and the transferring unit  40 . 
     The controller  19  communicates with the control unit  80  via e.g. an optical communication module  81 . That is, the electron beam irradiation unit  10  is also electrically isolated from the control unit  80 . Thus, it is possible to block the electrical noise from the other units via the control unit  80  to achieve the stable operation of the electron-beam gun  13 . Note that the optical communication module  81  may be e.g. a photo-coupler. Alternatively, the optical communication module comprises a system which includes optical transceivers provided in each of the controller  19  and the control unit  80 , and an optical fiber connected to the optical transceivers. 
     Further, the electron beam irradiation unit  10  may have a function for protecting the electron beam irradiation system from temperature change or composition change in atmosphere. For example, the electron beam irradiation unit  10  may comprises a temperature regulation system. Specifically, the controller  19  may adjust a temperature inside the electron beam irradiation unit  10  using a heater or a cooling device provided therein. The controller  19  may monitor e.g. an oxygen concentration inside the electron beam irradiation unit  10  using an atmosphere monitor, and control the pressure therein using a vacuum pump (not shown). 
     The dry etching unit  20  includes a wafer stage  21 , a high-frequency power source  22 , a pressure control device  23 , a mass flow controller  25 , and a controller  27 . The controller  27  fills the dry etching unit  20  with an atmosphere containing an etching gas at predetermined pressure, using the pressure control device  23  and the mass flow controller  25 . Then, the controller  27  excites plasma between the wafer  43  placed on the wafer stage  21  and an electrode (not shown) using the high-frequency power source  22 , thereby etching a surface of the wafer  43 . 
     The dry etching unit  20  includes a gate valve  29  between the transferring unit  40  and itself. The controller  27  opens and closes the gate valve  29 . The carrying robot  41  places the wafer  43  on the wafer stage  21  and takes the wafer from the wafer stage  21  through the gate valve. 
     The plasma irradiation unit  30  includes a wafer stage  31 , a high-frequency power source  32 , a pressure control device  33 , a mass flow controller  35 , and a controller  37 . The controller  37  sends commands to the pressure control device  33  and the mass flow controller  35  to fill the interior of the plasma irradiation unit  30  with an inert gas at predetermined pressure. Then, the controller  37  excites plasma between the wafer  43  placed on the wafer stage  31  and an electrode (not shown) using the high-frequency power source  32 , thereby exposing the surface of the wafer  43  to the plasma. 
     The condition of plasma excitation is preferably selected depending on a resist to be reformed. For example, when reforming a region limited to an extremely thin surface layer of the resist, an inert gas such as nitride or argon is preferably used. When reforming over a deeper region from the surface of the resist, a sedimentary gas such as methane or perfluorocyclobutane may be used. 
     The plasma irradiation unit  30  further includes a gate valve  39  between the transferring unit  40  and itself. The controller  37  opens and closes the gate valve  39 . The carrying robot  41  places the wafer  43  on the wafer stage  31  and takes the wafer from the wafer stage  31  through the gate valve  39 . 
     The temperature adjustment unit  60  includes a wafer stage  61 , a controller  63 , and an isolation wall  67 . The controller  63  may hold the wafer stage  61  at a predetermined temperature using e.g. a heater or cooling device (not shown) that is provided in the wafer stage  61 . 
     The isolation wall  67  thermally isolates the transferring unit  40  from the temperature adjustment unit  60 . That is, the isolation wall  67  is a connecting body made of a heat insulating material provided between the transferring unit  40  and the temperature adjustment unit  60 . Further, the isolation wall  67  includes a gate valve that provides a pathway between the transferring unit  40  and the temperature adjustment unit  60 . 
     The temperature adjustment unit  70  includes a wafer stage  71 , a controller  73 , and an isolation wall  77 . The controller  73  holds the wafer stage  71  at a predetermined temperature using e.g. a heater or cooling device (not shown) contained in the wafer stage  71 . 
     The isolation wail  77  thermally isolates the transferring unit  40  from the temperature adjustment unit  70 . That is, the isolation wall  77  is a connecting body containing heat insulating material. Further, the isolation wall  77  includes a gate valve that makes a pathway between the transferring unit  40  and the temperature adjustment unit  70 . 
     The gate unit  50  includes a wafer stocker  51  and a controller  53 . The wafer stocker  51  temporarily holds the wafer  43  that is carried into the gate unit  51  from the outside or the wafer  43  after processing. The controller  53  controls a gale  55 , a gate valve  56  and a vacuum pump (not shown) when carrying the wafer  43  in the transferring unit  40  and carrying out the wafer  43  therefrom. The gate  55  is provided between the outside and the gate unit  50 . The gate valve  56  is provided between the transferring unit  40  and the gate unit  50 . The controller  53  sequentially opens and closes the gate  55  and the gate valve  56 , and controls the internal pressure of the gate unit  50  by using the vacuum pump. Thus, it may be possible to perform the carry-in and carry-out processes of the wafer  43  without breaking the reduced-pressure state in the transferring unit  40 . 
     Further, the gate unit  50  may include a neutralization device  57 . The neutralization device  57  irradiates the wafer  43  with a soft X-ray, for example, under atmospheric pressure to remove charges therefrom. Alternatively, the neutralization device  57  may generate corona discharge in the gate unit  50  for removing charges from the wafer  43 . 
     Next, a dry etching method using the multi-processing apparatus  1  will be explained with reference to  FIGS. 1, 2, and 3A to 3D .  FIG. 2  is a flowchart showing a dry etching method according to the first embodiment. In this example, a quartz substrate  101  is used as the wafer  43 .  FIGS. 3A to 3D  are schematic views showing a cross-section of the quartz substrate  101  at each step of the dry etching process. 
     Step S 01 : forming resist masks  105  on the quartz substrate  101 . As shown in  FIG. 3A , a chromium (Cr) film  103  is formed on the quartz substrate  101 . For example, a chemical amplification type resist having a thickness of  30  nanometers (nm) or less is applied onto the chromium film  103 , then, photolithography processes such as exposing, baking, and developing are performed to form the resist masks  105  on the chromium film  103 . These processes are performed outside the multi-processing apparatus  1 . 
     Step S 02 : carrying the quartz substrate  101  into the multi-processing apparatus  1 . For example, the controller  53  of the gate unit  50  receives a command from outside or the control unit  80 , sets the interior of the gate unit  50  at atmospheric pressure, and opens the carry-in gate  55 . Then, the controller  53  closes the gate  55  and reduces pressure within the gate unit  50 , when receiving a signal that indicates the quartz substrate  101  being placed on the wafer stocker  51 . 
     Step S 03 : transferring the quartz substrate  101  from the gate unit  50  to the electron beam irradiation unit  10 . For example, when the internal pressure of the gate unit  50  becomes the same as the internal pressure of the transferring unit  40  or lower than the internal pressure of the transferring unit  40 , the controller  53  opens the gate valve  56  on the transferring unit  40  side of the gate unit  50  and sends a signal to the control unit  80 . 
     When receiving the signal from the controller  53 , the control unit  80  sends a command to the carrying robot  41  for taking out the quartz substrate  101  from the gate unit  50 . Then, the carrying robot  41  takes out the quartz substrate  101  from the wafer stocker  51 , and sends a signal to the control unit  80 . 
     When receiving the signal that indicates the quartz substrate  101  being taken out from the wafer stocker  51 , the control unit  80  sends a command to the controller  53  to close the gate valve  56 . Further, the control unit  80  sends a command to the controller  19  of the electron beam irradiation unit  10  to open the gate valve communicating with the transferring unit  40 , The controller  19  sends a signal to the control unit  80 , which indicates the gate valve being opened. 
     When receiving the signal from the controller  19 , the control unit  80  sends a command to the carrying robot  41  to place the quartz substrate  101  on the wafer stage  11 . The carrying robot  41  sends a signal to the control unit  80 , which indicates the quartz substrate  101  being placed on the wafer stage  11 . 
     Step S 04 : irradiating the resist masks  105  on the quartz substrate  101  with an electron beam. The control unit  80  sends a command for executing electron beam irradiation to the controller  19  of the electron beam irradiation unit  10 . The controller  19  closes the gate valve communicating with the transferring unit  40  and reduces the pressure within the electron beam irradiation unit  10  to predetermined pressure (10 −5  Pa) or less. Then, the controller  19  sends a command to the electron-beam gun  13  to irradiate the quartz substrate  101  held on the wafer stage  11  with an electron beam. The electron-beam gun  13  irradiates an electron beam e.g. until the dose amount reaches 2 mC/μm 2 . Further, it is favorable to set the accelerating voltage so that over half amount of electrons may be stopped within a depth of 30 nm from the surface. 
       FIG. 3B  is a schematic cross-sectional view showing the quartz substrate  101  after electron beam irradiation. After the electron beam irradiation, resist masks  105   a  may have a lower oxygen content and higher carbon density than the resist masks  105  before electron beam irradiation. So-called “Onishi parameter” is smaller in the resist masks  105   a  than that in the resist masks  105 , and thus, etching resistance of the resist masks  105   a  is improved. Note that the Onishi parameter is expressed by the following formula, and shows a degree of etching resistance. 
       Onishi parameter=Total number of atoms/(Number of carbon atoms−Number of oxygen atoms)
 
     Here, the number of atoms is e.g. the number of respective elements contained in the chemical formula of the resist, and the total number of atoms is the total number of elements contained in the chemical formula. 
     Step S 05 : transferring the quartz substrate  101  from the electron beam irradiation unit  10  to the dry etching unit  20 . When completing the electron beam irradiation, the controller  19  of the electron beam irradiation unit  10  opens the gate valve communicating with the transferring unit  40  and sends a signal the control unit  80 , which indicates that the electron beam irradiation has been completed. 
     When receiving the signal from the controller  19 , the control unit  80  sends a command for taking out the quartz substrate  101  from the electron beam irradiation unit  10  to the carrying robot  41 . The carrying robot  41  takes out the quartz substrate  101  on the wafer stage  11  and sends a signal to the control unit  80 . 
     When receiving the signal indicating that the quartz substrate  101  has been taken out from the electron beam irradiation unit  10 , the control unit  80  sends a command to the controller  19  to close the gate valve. Then, the control unit  80  sends a command to the controller  27  of the dry etching unit  20  to open the gate valve  29  communicating with the transferring unit  40 . The controller  27  sends a signal to the control unit  80 , which indicates that the gate valve  29  has been opened. 
     When receiving the signal indicating that the gate valve  29  has been opened, the control unit  80  sends a command to the carrying robot  41  to place the quartz substrate  101  on the wafer stage  21  of the dry etching unit  20 . The carrying robot  41  sends a signal to the control unit  80 , which indicates that the quartz substrate  101 , has been placed on the wafer stage  2 L The internal pressure of the transferring unit  40  is maintained at 10 Pa or less in the transfer process during these procedures. 
     Step S 06 : selectively removing the chromium film  103  by using the resist masks  105   a  as shown in  FIG. 3C . The control unit  80  sends a command for executing dry etching to the controller  27  of the dry etching unit  20 . The controller  27  doses the gate valve  29  communicating with the transferring unit  40  and reduces the pressure within the dry etching unit  20  to predetermined pressure or less. Then, the controller  27  sends a command to the mass flow controller  25  to introduce the etching gas. Further, the controller sends a command to the pressure control device  23  to maintain the internal pressure of the dry etching unit  20  at the predetermined pressure. The controller  27  sends a command to the high-frequency power source  22  to output predetermined high-frequency power to excite plasma between e.g. the wafer stage  21  and an electrode (not shown). Then, the chromium film  103  is etched by a plasma-excited active element with an etching margin enlarged by the resist masks  105   a  that has the improved etching resistance. 
     When a predetermined etching time elapses, the controller  27  sends commands to the high-frequency power source  22  and the mass flow controller  25  to stop the high-frequency power output and the etching gas supply. Then, the controller sends a command to the pressure control device  23  to reduce the pressure within the dry etching unit  20  to pressure lower than the internal pressure of the transferring unit  40 . 
     Step S 07 : carrying out the quartz substrate  101  from the multi-processing apparatus  1 . The controller  27  of the dry etching unit  20  opens the gate valve  29  communicating with the transferring unit  40  and sends a signal to the control unit  80 , which indicates that the dry etching has been completed. 
     When receiving the signal from the controller  27 , the control unit  80  sends a command for taking out the quartz substrate  101  from the dry etching unit  20  to the carrying robot  41 . The carrying robot  41  takes out the quartz substrate  101  on the wafer stage  21  and sends a signal to the control unit  80 . 
     When receiving the signal indicating that the quartz substrate  101  has been taken out from the dry etching unit  20 , the control unit  80  sends a command to the controller  27  to dose the gate valve  29 . Then, the control unit  80  sends a command to the controller  53  of the gate unit  50  to open the gate valve  56  communicating with the transferring unit  40 . The controller  53  sends a signal to the control unit  80 , which indicates that the gate valve  56  has been opened. 
     When receiving the signal indicating that the gate valve  56  has been opened, the control unit  80  sends a command to the carrying robot  41  to place the quartz substrate  101  on the wafer stocker  51  of the gate unit  50 . The carrying robot  41  sends a signal to the control unit  80 , which indicates that the quartz substrate  101  has been placed on the wafer stocker  51 . 
     When receiving the signal indicating that the quartz substrate  101  has been placed on the wafer stocker  51 , the control unit  80  sends a command to the controller  53  for closing the gate valve  56 , The controller  53  closes the gate valve  56 , and then, returns the interior of the gate unit  50  to the atmospheric pressure and opens the carry-in gate  55  communicating with the outside. 
     Step S 08 : performing the post-processing after taking out the quartz substrate  101  from the multi-processing apparatus  1 , For example, the resist masks  105   a  on the quartz substrate  101  are removed by oxygen aching. As shown in  FIG. 3D , chromium films  103   a  is formed on the quartz substrate  101  with the predetermined shapes. 
     In the embodiment, the resist masks  105  are irradiated with the electron beam and reformed to the resist masks  105   a  with the improved etching resistance. Then, the quartz substrate  101  with the resist masks  105   a  formed thereon is transferred to the dry etching unit  20  in the reduced-pressure atmosphere at 10 Pa or less. Thereby, oxygen atoms taken into the resist masks  105   a  may be reduced during the transferring process; and it may be possible to avoid deterioration of the improved etching resistance. As a result, the process margin of dry etching may be enlarged, improving e.g. the dimensional accuracy of the pattern formed by etching, 
     Second Embodiment 
     A dry etching method according to the second embodiment will be explained with reference to  FIGS. 1, 4, and 5A to 5F .  FIG. 4  is a flowchart showing the dry etching method according to the second embodiment,  FIGS. 5A to 5F  are schematic views showing a cross-section of the quartz substrate  101  in a dry etching process. 
     Step S 21 : forming resist masks  113  on the quartz substrate  101 . As shown in  FIG. 5A , a chromium (Cr) film  103  is formed on the quartz substrate  101 . For example, a chemical amplification type resist having a thickness of 30 nanometers (nm) or less is applied onto the chromium film  103 , then, the resist masks  113  are formed through the photolithography process, such as light exposure, baking, and developing processing. These processes are performed outside of the multi-processing apparatus  1 . 
     Step S 22 : carrying the quartz substrate  101  with the resist masks  113  formed thereon into the multi-processing apparatus  1 . For example, the control unit  80  sets the interior of the gate unit  50  at atmospheric pressure, and opens the gate  55 . Then, the carry-in gate  55  is closed after the quartz substrate  101  is placed on the wafer stocker  51 , and pressure within the gate unit  50  is reduced. 
     Step S 23 : transferring the quartz substrate  101  from the gate unit  50  to the plasma irradiation unit  30 . For example, when the internal pressure of the gate unit  50  becomes the same as the internal pressure of the transferring unit  40  or lower than the internal pressure of the transferring unit  40 , the gate valve  56  communicating with the transferring unit  40  of the gate unit  50  is opened. The carrying robot  41  takes out the quartz substrate  101  from the wafer stocker  51  and places the substrate on the wafer stage  31  of the plasma irradiation unit  30 . 
     Step S 24 : exposing the resist masks  113  on the quartz substrate  101  to plasma. The controller  37  of the plasma irradiation unit  30  doses the gate valve  39  communicating with the transferring unit  40  and reduces pressure within the plasma irradiation unit  30 . When the pressure within the plasma irradiation unit  30  becomes predetermined pressure or less, the controller  37  sends a command to the mass flow controller  35  for introducing a gas therein. At the same time, the controller sends a command to the pressure control device  33  for maintaining the internal pressure of the plasma irradiation unit  30  at the predetermined pressure. Further, the controller  37  sends a command to the high-frequency power source  32  for outputting predetermined high-frequency power. Thereby, plasma is excited between the wafer stage  31  and the electrode (not shown). The resist masks  113  are reformed to improve the etching resistance thereof by exposing to the plasma. 
     As shown in  FIG. 5B , resist masks  113   a  after being exposed to the plasma may have e.g. higher carbon density, resulting in the smaller Onishi parameters. Thus, the etching resistance of the resist masks  113   a  is improved. 
     Step S 25 : transferring the quartz substrate  101  from the plasma irradiation unit  30  to the electron beam irradiation unit  10 . When completing plasma irradiation, the controller  37  of the plasma irradiation unit  30  opens the gate valve  39  communicating with the transferring unit  40 . 
     The carrying robot  41  takes out the quartz substrate  101  on the wafer stage  31  and transfers the quartz substrate  101  to the electron beam irradiation unit  10 . The quartz substrate  101  is placed on the wafer stage  11  in the electron beam irradiation unit  10 . 
     Step S 26 : irradiating the resist masks  113   a  on the quartz substrate  101  with an electron beam. The controller  19  closes the gate valve communicating with the transferring unit  40  and reduces the pressure within the electron beam irradiation unit  10  to predetermined pressure (10 −5  Pa) or less. Then, the controller  19  sends a command to the electron-beam gun  13  for irradiating the quartz substrate  101  held on the wafer stage  11  with an electron beam. The electron-beam gun  13  irradiates an electron beam e.g. until the dose amount reaches 2 mC/μm 2 . Further, it is favorable to set the accelerating voltage so that over half amount of electrons may be stopped in the surface layer within a depth of 30 nm. 
       FIG. 5C  is a schematic cross-sectional view showing the quartz substrate  101  after the electron beam irradiation. The electron-beam gun  13  may selectively irradiates an electron beam e.g. on the quartz substrate  101 . That is, the resist masks  113   a  and  113   b  are selectively formed on the quartz substrate  101 . The resist mask  113   b  is irradiated with the electron beam, and the resist mask  113   a  is not irradiated with the electron beam. The resist mask  113   b  has e.g. lower oxygen content and a higher carbon density than those of the resist mask  113   a.  An Onishi parameter of the resist mask  113   b  is smaller than an Onishi parameter of the resist mask  113   a,  i.e. the etching resistance is further improved in the resist mask  113   b.    
     Step S 27 : transferring the quartz substrate  101  from the electron beam irradiation unit  10  to the dry etching unit  20 . 
     When completing the electron beam irradiation, the controller  19  of the electron beam irradiation unit  10  opens the gate valve communicating with the transferring unit  40 . The carrying robot  41  takes out the quartz substrate  101  on the wafer stage  11  and transfers the substrate to the dry etching unit  20 . The quartz substrate  101  is placed on the wafer stage  21 . 
     Step S 28 : selectively removing the chromium film  103  using the resist masks  113   a,    113   b  as shown in  FIG. 5D . The controller  27  of the dry etching unit  20  closes the gate valve  29  communicating with the transferring unit  40  and reduces the pressure within the dry etching unit  20  to predetermined pressure or less. Subsequently, the controller  27  sends a command to the mass flow controller  25  for introducing the etching gas. Further, the controller sends a command to the pressure control device  23  for maintaining the internal pressure of the dry etching unit  20  at the predetermined pressure. The controller  27  sends a command to the high-frequency power source  22  for outputting predetermined high-frequency power to excite plasma between the wafer stage  21  and the electrode (not shown). Then, the chromium film  103  is etched by a plasma-excited active element. 
     When a predetermined etching time elapses, the controller  27  sends commands to the high-frequency power source  22  and the mass flow controller  25  for stopping the high-frequency power output and the etching gas supply. Then, the controller sends a command to the pressure control device  23  for reducing the pressure within the dry etching unit  20  to the pressure lower than the internal pressure of the transferring unit  40 . 
     When the chromium film  103  is selectively etched, the resist mask  113   a  may be completely removed as shown in  FIG. 5D , since the resist mask  113   a  has the lower etching resistance than that of the resist mask  113   b.  On the other hand, the resist mask  113   b  remains on chromium films  103   b.    
     For example, the quartz substrate  101  is further etched to form recessed portions  115  on the quartz substrate  101  as shown in FIG,  5 E. In this case, the chromium films  103   a  may be removed under a condition of etching the chromium films  103   a,  leaving the chromium films  103   b  covered by the resist masks  113   b.    
     Step S 29 : carrying the quartz substrate  101  out from the multi-processing apparatus  1 . The controller  27  of the dry etching unit  20  opens the gate valve  29  communicating with the transferring unit  40 . The carrying robot  41  takes out the quartz substrate  101  on the wafer stage  21  and transfers the quartz substrate  101  to the wafer stocker  51  in the gate unit  50 . 
     The controller  53  of the gate unit  50  closes the gate valve  56 , returns the interior of the gate unit  50  to the atmospheric pressure, and then, opens the carry-in gate  55  communicating with the outside. 
     Step S 30 : performing the post-processing after the quartz substrate  101  is taken out from the multi-processing apparatus  1 . For example, the resist masks  113   b  remains the quartz substrate  101  are removed by oxygen ashing. Thereby, the chromium films  103   b  with predetermined shapes and the recessed portions  115  are formed on the quartz substrate  101  as shown in  FIG. 5E . 
     In this example, the control unit  80  also controls the operation of the multi-processing apparatus  1  via the controllers of the respective units. Although involvement of the control units  80  in the etching procedures is omitted in the above explanation, it is obvious that the control units send commands to the respective controllers like the steps S 02  to S 07  described in the first embodiment. 
     In the embodiment, the resist masks  113  are irradiated with plasma, and further, selectively irradiated with the electron beam. Thereby, two kinds of resist masks having different etching resistance may be formed on a substrate, and makes etching procedures being more flexibly designed. Further, the resist mask  113  may be prevented from deterioration of the improved etching resistance, since the quartz substrate  101  with the resist masks  113  formed thereon is transferred in the reduced-pressure atmosphere at 10 Pa or less. Thereby, it may be possible to enlarge the process margin of dry etching. 
     Third Embodiment 
     The gate unit  50  of the multi-processing apparatus  1  shown in  FIG. 1  may include the neutralization device  57 . The neutralization device  57  removes charges of the quartz substrate  101  placed on the wafer stocker  51  in the gate unit  50 . 
     For example, at step S 02  shown in  FIG. 2 , the controller  53  of the gate unit  50  sends a command to the neutralization device  57  for removing the charges of the quartz substrate  101  on the wafer stocker  51  before reducing pressure in the gate unit  50 . Specifically, for example, the quartz substrate  101  is irradiated with a soft X-ray emitted from the neutralization device  57 . Subsequently, the step S 03  and the subsequent steps in  FIG. 2  are executed. 
     The soft X-ray emitted from the neutralization device generates the ionized atoms in the atmosphere, which neutralizes the charges of the quartz substrate  101 . Thereby, variations in the dose amount of electrons due to a potential distribution in the quartz substrate  101  may be reduced. Further, it becomes possible to suppress a displacement of the irradiated position in the quartz substrate  101 , when being selectively irradiated with the electron beam. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.