Abstract:
An apparatus and a method for surface treatment of substrates whereby the quality of substrates can be maintained by preventing excessive plasma treatment of substrates. In carrying out the plasma treatment on a surface of the substrate in a reaction chamber, there are provided an emission spectroscopic analysis device or a mass analyzer, and a controller, so that the energy of ions in plasma is controlled to decrease when, e.g., bromine included in the substrate is detected, and the surface treatment to the substrate is controlled to stop when the removal of impurities of the substrate is detected to end. The bromine once separated from the substrate is prevented from adhering again to the substrate and corroding the substrate. Moreover, ions are prevented from being excessively irradiated to the substrate when the removal of impurities ends, thereby reducing damage to the substrate.

Description:
[0001]     This is a divisional application of Ser. No. 10/233,440 filed Sep. 4, 2002. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an apparatus for executing surface treatment such as cleaning, modifying or the like on substrate surfaces by plasma, and a method for substrate surface treatment carried out by the substrate surface treatment apparatus.  
         [0003]     High-packaging density has been required in the field of a mounting technique in accordance with miniaturization and multifunction of electronic devices. Consequently, connections between elements and substrates should be carried out on a remarkably fine scale, and mounting with a higher degree of reliability is being required. There currently is a method of modifying substrate surfaces by plasma, i.e., plasma treatment as one example for securing the reliability. For instance, the plasma treatment can remove an organic contaminant adhering to the substrate surface, and the bonding strength between a gold electrode and a wire in the case of wire bonding can be improved when an inorganic substance such as nickel hydroxide or the like deposited on an electrode face as a bonding face formed of copper, nickel, and gold on a printed board is removed by the sputtering action of argon plasma. Also in the case where an IC is to be bonded to a lead electrode on a polyimide film substrate via an ACF (anisotropic conductive film), the bonding strength between the polyimide film and the ACF can be improved through activation of a surface of the polyimide film substrate by irradiating oxygen plasma to the film before bonding. Moreover, the plasma treatment carried out on the substrate improves the fluidity of a sealing resin on the substrate and the adhesion between the substrate and the sealing resin.  
         [0004]     An example of the plasma treatment method referred to above will be described below with reference to the drawing  FIGS. 3-5 .  
         [0005]      FIG. 3  roughly shows the configuration of a conventional apparatus  20  for surface treatment of mounting substrates, in which a reaction chamber  1  being grounded is provided with a gas introduction port  2  and a vacuum exhaust port  3 . A RF electrode  5  is arranged in the reaction chamber  1  via an insulating ring  4  to a side wall of the reaction chamber  1 . The RF electrode  5  has a constitution on which a mounting substrate  6  can be placed. An opposed electrode  7  is arranged in the reaction chamber  1  so as to face the RF electrode  5  and is grounded. A RF(Radio-Frequency) is applied to the RF electrode  5  by a RF supply source  8  through a matching tuner (not shown) and a RF power supply part. O-rings (not shown) are interposed between the RF electrode  5  and the insulating ring  4  and between the insulating ring  4  and the side wall of the reaction chamber  1 . For preventing the O-rings from being heated to 200° C. or higher and maintaining the reaction chamber  1  in vacuum, a cooling groove  9  where a cooling water flows is formed in the side wall of the reaction chamber  1 .  
         [0006]     The surface treatment method to mounting substrates carried out by the above-constituted surface treatment apparatus  20  will be described hereinbelow in an example in which an argon gas is used for substrates before wire bonding.  
         [0007]     The substrate  6 , before being subjected to wire bonding, is placed on the RF electrode  5 . While a degree of vacuum in the reaction chamber  1  is kept to be 30 Pa with 50SCCM (standard cc/min) of the argon gas being supplied from the gas introduction port  2 , a RF(Radio-Frequency) of 200 W is applied to the RF electrode  5 , thereby generating plasma. Argon ions in the plasma are irradiated onto a face of the substrate  6  exposed in the plasma. The substrate  6  is formed of glass cloth epoxy resin. An electrode  10  formed on the surface of the substrate  6  is constituted of three layers of a copper layer  11  having a film thickness of 35 μm, a nickel layer  12  having a film thickness of 3 μm and a gold layer  13  having a film thickness of 0.05 μm as shown in  FIG. 4 . The undercoat nickel  12  is moved onto a surface of the gold  13  through a heat process or the like, whereby nickel hydroxide or the like is deposited. The nickel hydroxide is sputtered and removed by the irradiation of argon ions. The surface of the gold  13  is cleaned accordingly.  
         [0008]      FIG. 5  is a schematic diagram of a case in which a silicon chip IC  16  is bonded via an ACF (anisotropic conductive film)  15  to a polyimide film substrate  14 . As shown in  FIG. 5 , electrodes  18  of the IC  16  are bonded via the ACF  15  composed of a resin containing conductive particles to electrode parts  17  on the polyimide film substrate  14 . A surface treatment method for the polyimide film substrate  14  having the above constitution will be described below.  
         [0009]     The polyimide film substrate  14  is placed on the RF electrode  5 . A RF(Radio-Frequency) of 200 W is applied to the RF electrode  5  while a degree of vacuum in the vacuum chamber  1  is maintained at 30 Pa with 50SCCM of an oxygen gas supplied from the gas introduction port  2 . As a result, plasma is generated. Oxygen radicals or oxygen ions present in the plasma are irradiated onto a surface of the polyimide film substrate  14  exposed in the plasma. The oxygen radicals react with contamination organic substances adhering on the polyimide film substrate  14 , whereby the contamination organic substances are decomposed to be sublimation compounds such as CO 2  or the like and then removed. Further, functional groups such as C═O, COOH and the like are generated on the surface of the polyimide film substrate  14 , activating the surface of the polyimide film substrate. The bonding strength between the polyimide film substrate  14  and the ACF  15  is improved accordingly.  
         [0010]     In the case of polyimide film substrate  14 , residual ions of chlorine or the like are left yet on the polyimide film substrate  14  when the apparatus receives the polyimide film substrate  14 . The reason for this is that hydrochloric acid is used as one of components of a plating solution for forming a pattern of the electrodes  17  on the polyimide film substrate  14  by plating, and, for example, chlorine ions are left if the substrate is not fully cleaned by water after the pattern is formed. In the event that the IC  16  is connected with the use of the ACF  15  to the polyimide film substrate  14  having the residual ions, the residual ions cause corrosion and electrical failures such as ion migration, etc. As such, the plasma treatment is carried out to remove the chlorine ions.  
         [0011]     However, if the plasma treatment is carried out on the substrate  6  before being subjected to wire bonding, not only the organic contaminant, inorganic substance, or the like, but the substrate  6  is sputtered by argon ions simultaneously. In the case of the substrate  6  formed of glass cloth epoxy resin, Br (bromine) included in the substrate  6  adheres again to the substrate after being separated from the substrate  6  by the plasma treatment. In the case of the Br adhering to the electrode  10 , the trouble is that the Br adhering on the electrode  10  reacts with moisture in the air and becomes HOBr or HBr when the substrate  6  is exposed to the atmosphere, which causes corrosion of the electrode  10 .  
         [0012]     When the plasma treatment is carried out with the aim of removing residual ions adhering to the polyimide film substrate  14 , since there is no means for observing whether or not the residual ions are actually removed, the plasma treatment may be executed to an excessive stage in order to perfectly remove the residual ions. Thus the trouble is that the excessive plasma treatment may also damage the polyimide film substrate  14 .  
       SUMMARY OF THE INVENTION  
       [0013]     Accordingly, the present invention is devised to solve the above-discussed problems inherent in the conventional art and an object of the present invention is to provide an apparatus and a method for surface treatment to substrates whereby the substrate quality can be maintained by preventing an excessive plasma treatment to the substrates.  
         [0014]     In accomplishing the above objective, according to a first aspect of the present invention, there is provided a substrate surface treatment apparatus for executing surface treatment of a substrate arranged in a reaction chamber by ions in plasma generated in the reaction chamber, which comprises:  
         [0015]     a detecting device arranged adjacent to the reaction chamber for detecting at least whether or not components constituting the substrate are separated from the substrate, or whether or not impurities adhering to a surface of the substrate are removed by the surface treatment; and  
         [0016]     a controller connected to the detecting device for reducing an energy of the ions in the plasma on the basis of the detected information by the detecting device when the separation of components is brought about, and for terminating the surface treatment on the basis of the detected information by the detecting device when the removal of impurities ends.  
         [0017]     The substrate surface treatment apparatus may be further provided with a plasma generating device including electrodes arranged in the reaction chamber for generating the plasma and a power supply unit for supplying electricity to the electrodes, and  
         [0018]     a vacuum degree adjusting device connected to the reaction chamber for adjusting a degree of vacuum in the reaction chamber.  
         [0019]     The controller controls operations of the power supply unit and the vacuum degree adjusting device on the basis of the detected information by the detecting device so as to control reduction of the energy of the ions and to end the surface treatment.  
         [0020]     The above detecting device may be comprised of a spectroscopic analyzer for conducting spectral observation of light generated by the plasma and detecting the components and the impurities of the substrate on the basis of the observation.  
         [0021]     The above detecting device may be comprised of a mass analyzer for analyzing gas elements in the reaction chamber and detecting the components and the impurities of the substrate on the basis of the gas analysis.  
         [0022]     The components of the substrate to be detected by the detecting device may be bromine (Br).  
         [0023]     The impurities to be detected by the detecting device may be chlorine.  
         [0024]     According to a second aspect of the present invention, there is provided a substrate surface treatment method for executing surface treatment of a substrate arranged in a reaction chamber by ions in plasma generated in the reaction chamber, which comprises:  
         [0025]     detecting at least either whether or not components constituting the substrate are separated from the substrate by the surface treatment, or whether or not impurities adhering to a surface of the substrate are removed by the surface treatment; and  
         [0026]     controlling on a basis of the detected information an energy of the ions in the plasma to reduce when the separation of components is detected to take place and the surface treatment to end when the removal of impurities is detected to end.  
         [0027]     By the above construction of the aspects of the present invention, there are provided the detecting device and the controller, so that the energy of ions in the plasma is controlled to decrease when the constituent separated from the substrate is detected, and the surface treatment to the substrate is controlled to terminate when the completion of removing impurities adhering to the substrate is detected. In the arrangement as above, the constituent of the substrate can be prevented from separating and scattering from the substrate. Therefore the phenomenon that the separated constituent from the substrate adheres again to the substrate and the redeposit of the separated constituent causes corrosion to the substrate is avoided. Furthermore, the ions are prevented from excessively irradiating the substrate when the removal of impurities is completed, therefore reducing damage to the substrate.  
         [0028]     The first embodiment and the second embodiment of the present invention enable the prevention of excessive plasma treatment of substrates while maintaining the quality of the substrates.  
         [0029]     When the plasma generating device and the vacuum degree adjusting device are provided additionally, the controller can control the power supply unit installed at the plasma generating device and the vacuum degree adjusting device on the basis of detected information by the detecting device. In other words, the power to be supplied to the electrode in the plasma generating device is reduced by controlling the power supply unit, so that the energy of ions in the plasma can be decreased. As a result, the efficiency for sputtering can be lowered. Moreover, a collision probability between gas molecules and ions in the reaction chamber increases by raising the pressure in the reaction chamber by the vacuum degree adjusting device, and eventually the energy of the ions can be decreased. Furthermore, the plasma treatment can be stopped by, e.g., stopping the power supply.  
         [0030]     When the spectroscopic analyzer is used as the detecting device, the detecting device can be arranged on the outside of the reaction chamber, and the whole construction of the substrate surface treatment apparatus is simplified.  
         [0031]     When the mass analyzer is used as the detecting device, the constituent and impurities of the substrate can be detected with a higher degree of accuracy than by the spectroscopic analyzer, thus enabling the quality of the substrate to be maintained at a high level. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]     These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings in which:  
         [0033]      FIG. 1  is a schematic diagram of the configuration of a surface treatment apparatus for substrates according to a first embodiment of the present invention;  
         [0034]      FIG. 2  is a schematic diagram of the configuration of a surface treatment apparatus for substrates according to a second embodiment of the present invention;  
         [0035]      FIG. 3  is a schematic diagram of the configuration of a conventional surface treatment apparatus for substrates;  
         [0036]      FIG. 4  is a diagram showing the constitution of a substrate electrode; and  
         [0037]      FIG. 5  is a diagram for briefly explaining bonding when an IC chip is bonded via an ACF to a film substrate. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0038]     An apparatus for surface treatment of substrates and a method for surface treatment of substrates which is carried out by the apparatus according to the preferred embodiments of the present invention will be described below with reference to the attached drawings. It is to be is noted that like parts are designated by like reference numerals throughout the accompanying drawings.  
       First Embodiment  
       [0039]      FIG. 1  is a schematic diagram showing the construction of a substrate surface treatment apparatus  101  according to a first embodiment. Roughly speaking, the apparatus  101  has a reaction chamber  110 , a plasma generating device  120 , a vacuum degree adjusting device  130 , a detecting device  140 , and a controller  150 . The reaction chamber  110  in which a substrate  109  is stored is a vessel for carrying out surface treatment by plasma to the substrate  109 , which comprises a reaction gas introduction port  111 , an exhaust port  112  and an observation window  113 , and is grounded. To the reaction gas introduction port  111  is connected a reaction gas supply unit  161  which supplies a reaction gas for generating desired ions into the reaction chamber  110  via the reaction gas introduction port  111 . The operation of the reaction gas supply unit  161  is controlled by the controller  150 .  
         [0040]     Inside the reaction chamber  110 , there is arranged an electrode  121  connected via an insulating ring  162  to a side wall  110   a  of the reaction chamber  110 . The electrode  121  is constituted so that the substrate  109  can be placed on the electrode  121 . O-rings are interposed between the electrode  121  and the insulating ring  162  and between the insulating ring  162  and the side wall  110   a , whereby the reaction chamber  110  is kept in vacuum. Moreover, a cooling groove  163  for passing a coolant, e.g., cooling water, is formed in the side wall  110   a  so as to prevent the O-rings from being heated to 200° C. or more. A coolant supply unit  164  which is controlled in operation by the controller  150  for supplying the coolant, i.e., cooling water in this embodiment is connected to the cooling groove  163 .  
         [0041]     Also in the reaction chamber  110 , an opposed electrode  122 , which is grounded, is arranged opposite to the electrode  121 . A RF(Radio-Frequency) is applied to the electrode  121  by a power supply unit  123  including a matching tuner and a RF power supply part. The plasma generating device  120  is constituted of the electrode  121 , the opposed electrode  122  and the power supply unit  123 . The operation of the power supply unit  123  is controlled by the controller  150 . Plasma can be generated between the electrode  121  and the opposed electrode  122  by supplying the RF to the electrode  121  in the reaction chamber  110  to which a predetermined reaction gas is supplied in a vacuum state.  
         [0042]     According to the embodiment, an emission spectroscopic analysis device  141  is arranged as an example of a spectroscopic analyzer and the detecting device  140  for observing a state of the plasma in the reaction chamber  110  from the outside of the apparatus, and more specifically, for observing an emission state of the plasma from the outside of the apparatus. The emission spectroscopic analysis device  141  is disposed adjacent to the observation window  113 . Although described in detail later, the detecting device  140  detects at least either whether or not components constituting the substrate  109  are separated from the substrate  109  by the surface treatment carried out on the substrate  109  with the utilization of the plasma, or whether or not impurities adhering to a surface of the substrate  109  are removed by the surface treatment.  
         [0043]     The vacuum degree adjusting device  130  connected to the reaction chamber  110  is a device for adjusting the degree of vacuum in the reaction chamber  110 . The vacuum degree adjusting device  130  has a valve  131  for shutting the inside from the outside of the reaction chamber  110 , more precisely, for shutting the inside from a vacuum pump  133  to be described below, a valve switch  132  for controlling an opening degree of the valve  131 , and the vacuum pump  133  for turning the interior of the reaction chamber  110  to vacuum via the valve  131 . As will be detailed later, the vacuum degree adjusting device  130  adjusts the degree of vacuum inside the reaction chamber  110  in accordance with a control signal sent from the controller  150  on the basis of detected information sent from the detecting device  140 , namely, the emission spectroscopic analysis device  141  in the embodiment to the controller  150 . Specifically, the control signal is supplied to the valve switch  132 , whereby the valve  131  is opened at the opening degree conforming to the control signal. The degree of vacuum in the reaction chamber  110  is adjusted in this manner.  
         [0044]     Operation, i.e., the surface treatment method in the above-constituted substrate surface treatment apparatus  101  will be described below. The controller  150  carries out control related to the substrate surface treatment method. The following description is based on a state in which the substrate  109  is already placed on the electrode  121 .  
         [0045]     While the air in the reaction chamber  110  is discharged by the vacuum pump  133 , 50SCCM of an argon gas is supplied from the reaction gas introduction port  111  by the reaction gas supply unit  161  so that the reaction chamber  110  is held in a degree of vacuum of 30 Pa. In this state, 200 W RF(Radio-Frequency) is applied to the electrode  121  from the power supply unit  123  to generate plasma between the electrode  121  and the opposed electrode  122  in the reaction chamber  110 . Argon ions present in the plasma are irradiated to the surface of the substrate  109  exposed in the plasma. Although nickel hydroxide or the like is deposited onto a surface of the electrode  10 , which is formed of gold on the substrate  109  in the same arrangement as that described with reference to  FIG. 4 , through a heat process or the like as discussed in the “BACKGROUND OF THE INVENTION”, the nickel hydroxide or the like is removed by the sputtering action because of the irradiation of argon ions, and therefore, the surface of the electrode  10  formed of gold is cleaned.  
         [0046]     At this time, the surface of the substrate  109  except the electrode  10  is also sputtered by the irradiation of argon ions. In the case where the substrate  109  is formed of glass cloth epoxy resin, Br (bromine) as one of components constituting the substrate  109  is sputtered as well, emitted into the reaction chamber  110 . Thus, there is the apprehension that the emitted Br will again adhere to the surface of the substrate  109 .  
         [0047]     Meanwhile, according to the present embodiment, the plasma state in the reaction chamber  110  is monitored at all times through the observation window  113  by the emission spectroscopic analysis device  141 . The emission spectroscopic analysis device  141  sends a signal to the controller  150  at a time point when an emission spectrum of the Br is observed. The controller  150  in return controls and adjusts the power supply unit  123  and the valve switch  132  to reduce the energy of argon ions in the plasma to prevent the Br from being sputtered. More specifically, the controller  150  decreases the electric power to be supplied from the power supply unit  123  to the electrode  121  and also drives the valve  131  in a direction to close the valve to raise the pressure in the reaction chamber  110 . Since the energy of argon ions is reduced by decreasing the electric power, the efficiency for sputtering can be deteriorated. At the same time, a collision probability between gas molecules and the argon ions in the reaction chamber  110  is increased by raising the pressure, and eventually the energy of argon ions is reduced. Thus, the sputtering efficiency can be decreased. Accordingly, only the nickel hydroxide deposited on the electrode  10  of the substrate  109  can be removed by the sputtering action through the irradiation of argon ions, while the Br contained in the substrate  109  is prevented from being sputtered.  
         [0048]     The sputtering efficiency to the nickel hydroxide is deteriorated by the reduction in the energy of argon ions as above. But, where the nickel hydroxide is deposited is the surface of the electrode  10  as mentioned above, and therefore the nickel hydroxide is sputtered with priority by the irradiation of argon ions. In contrast, since the Br is included in the substrate  109 , the amount of Br to be sputtered is relatively small. That is, the sequence of the above operations is based on the idea that the nickel hydroxide has been removed as much as possible before the Br is emitted from the substrate  109 .  
         [0049]     Since the nickel hydroxide can be removed from the surface of the gold electrode  10  of the substrate  109 , the bonding strength between the gold electrode  10  and a wire can be improved when the gold electrode  10  is to be wire bonded.  
         [0050]     According to the embodiment as described hereinabove, in processing the substrate  109  formed of glass cloth epoxy resin by argon plasma, the plasma state in the reaction chamber  110  is always monitored through the observation window  113  by the emission spectroscopic analysis device  141 , and the controller  150  controls the power supply unit  123  and the valve switch  132  to adjust so as not to sputter the Br when the emission spectrum of the Br is observed. Therefore, only the nickel hydroxide deposited on the gold electrode  10  of the substrate  109  can be removed by irradiating argon ions while the Br as a constituent of the substrate  109  is prevented from scattering. In consequence of this, the phenomenon that the sputtered Br adheres again to the substrate  6  does not arise, and the conventional trouble that the Br and the moisture in the air react with each other when the substrate  6  having the Br adhering to the electrode  10  is exposed to the atmosphere, thereby forming HOBr or HBr, does not arise. Therefore, the corrosion of the electrode  10  of the substrate  109  can be prevented.  
         [0051]     In the present embodiment, the controller  150  controls both of the power supply unit  123  and the valve switch  132  when the emission spectrum of the Br is observed. However, the aforementioned effect is obtained by controlling at least one of the power supply unit  123  and the valve switch  132  as is apparent from the foregoing description.  
         [0052]     The substrate  109  is formed of glass cloth epoxy resin in the above description. Hereinbelow will be discussed the substrate  109  formed of a polyimide film.  
         [0053]     As is described in the “BACKGROUND OF THE INVENTION”, in the case of the substrate  109  formed of a polyimide film, chlorine ions are sometimes left as an example of impurities on the surface of the substrate  109  if cleaning at a manufacturing time of the substrate is insufficient. For removing the chlorine ions, an oxygen gas is supplied by 50SCCM into the reaction chamber  110  through the reaction gas introduction port  111  by the reaction gas supply unit  161 . While the degree of vacuum in the reaction chamber  110  is maintained at 30 Pa, 200 W RF(Radio-Frequency) is applied to the electrode  121 , thereby generating plasma. Oxygen ions present in the plasma are irradiated onto the surface of the substrate  109  exposed in the plasma, which sputter and remove residual chlorine ions on the surface of the substrate  109 .  
         [0054]     In the meantime, the plasma state in the reaction chamber  110  is monitored at all times by the emission spectroscopic analysis device  141  through the observation window  113 . The emission spectroscopic analysis device  141  observes an emission spectrum of chlorine. At a time point when the removal of impurities terminates, that is, the emission spectrum of chlorine disappears or the emission spectrum of chlorine decreases to a level where no trouble is substantially brought about, the emission spectroscopic analysis device  141  sends a signal to the controller  150 , and the controller  150  controls the power supply unit  123 , the valve switch  132  and the reaction gas supply unit  161  to stop the plasma treatment.  
         [0055]     Since the chlorine ions remaining at the substrate  109  formed of the polyimide film can be removed in the manner as above, the problems of corrosion due to residual ions, electrical failures such as ion migration or the like, which are caused by connecting the IC with the use of ACF in a state in which chlorine ions remain, can be prevented.  
         [0056]     In addition, by observing the emission spectrum of chlorine by the emission spectroscopic analysis device  141 , the plasma treatment of the substrate  109  is stopped when chlorine as an impurity is removed. Therefore, chlorine ions remaining at the substrate  109  can be removed while the effect of oxygen ions to the substrate  109  is restricted to a minimum. At the same time, since the substrate  109  is formed of polyimide, an organic contaminant at the polyimide surface can be removed by the oxygen radicals and oxygen ions as described in the “BACKGROUND OF THE INVENTION”, and also functional groups such as C═O, COOH, etc. are formed on the surface, thereby activating the surface of the substrate  109 . The bonding strength between the substrate and the ACF is improved accordingly.  
       Second Embodiment  
       [0057]     The above substrate surface treatment apparatus  101  is exemplified in the arrangement of using the emission spectroscopic analysis device  141  as the detecting device  140  as shown in  FIG. 1 . The detecting device  140  is not limited to the emission spectroscopic analysis device, and a mass analyzer  142  may be employed as will be described below with reference to  FIG. 2 .  
         [0058]     A substrate surface treatment apparatus  102  indicated in  FIG. 2  is constituted including the mass analyzer  142  in place of the emission spectroscopic analysis device  141  installed in the foregoing substrate surface treatment apparatus  101 . The same parts in the substrate surface treatment apparatus  102  as those of the substrate surface treatment apparatus  101  are designated by the same reference numerals, and thus are omitted from the description. Only different parts will be discussed below.  
         [0059]     Since the emission spectroscopic analysis device  141  is eliminated from the substrate surface treatment apparatus  102 , no observation window  113  is formed in the reaction chamber  110 . On the other hand, the mass analyzer  142  is mounted on the exhaust port  112  communicating with the valve  131  from the reaction chamber  110  so as to analyze a plurality of gas elements present at the exhaust port  112 , that is, in the reaction chamber  110 . The mass analyzer  142  is connected to the controller  150 .  
         [0060]     The operation, i.e., surface treatment method in the substrate surface treatment apparatus  102  constructed as above, will be described hereinbelow. Comparing the substrate surface treatment method in the apparatus  102  with that in the apparatus  101 , only the manner of detecting a detection object in the reaction chamber  110  is different while the operation and effect obtained in the apparatus  102  are fundamentally equal to the operation and effect exerted in the apparatus  101 . Therefore, an operation of detecting the detection object will be primarily described below, with the rest being omitted from the description or roughly described.  
         [0061]     In the case where the substrate  109  is formed of the glass cloth epoxy resin material, an argon gas is supplied by 50SCCM into the reaction chamber  110  from the reaction gas introduction port  111  while the air in the reaction chamber  110  is discharged by the vacuum pump  133 . In a state with the reaction chamber maintained at 30 Pa of the degree of vacuum, 200 W RF is applied to the electrode  121  thereby generating plasma. Similar to the case of the substrate surface treatment apparatus  101 , argon ions in the plasma are irradiated to the surface of the substrate  109 , and nickel hydroxide or the like deposited on the surface of the gold electrode  10  is removed by sputtering. On the other hand, a plurality of kinds of gases present in the reaction chamber  110  are monitored by the mass analyzer  142  at all times after the reaction chamber  110  reaches a specified degree of vacuum or when the plasma is generated. The mass analyzer  142  sends a signal to the controller  150  when the element Br, separated from the substrate  109  formed of the glass cloth epoxy resin material and emitted to the reaction chamber  110 , is observed. Based on the supply of the signal, the controller  150  controls the power supply unit  123  and the valve switch  132  to prevent the Br from being sputtered. Accordingly, only the nickel hydroxide deposited on the gold electrode  10  of the substrate  109  can be removed by the irradiation of argon ions without scattering the Br as a constituent of the substrate  109 . Corrosion of the electrode  10  caused by the Br can be thus prevented.  
         [0062]     The controller  150  controls both of the power supply unit  123  and the valve switch  132  when the mass analyzer  142  detects the Br. However, the above-described effect can be obtained by controlling at least one of the power supply unit  123  and the valve switch  132 .  
         [0063]     If the substrate  109  is formed of a polyimide film, in order to eliminate residual chlorine ions, the oxygen gas is supplied by 50SCCM into the reaction chamber  110  while the air in the reaction chamber  110  is discharged by the vacuum pump  133  so that the reaction chamber  110  is maintained at the degree of vacuum of 30 Pa. In this state, 200 W RF is applied to the electrode  121 , thereby generating plasma. Oxygen ions present in the plasma are irradiated onto the surface of the substrate  109  exposed in the plasma. Residual chlorine ions on the surface of the substrate  109  are hence removed.  
         [0064]     The mass analyzer  142  always monitors gases present in the reaction chamber  110 . When impurities are completely removed, that is, when the chlorine is not detected in the embodiment or when a concentration of the chlorine decreases to a level where no trouble is brought about, the mass analyzer  142  sends a signal to the controller  150 . In response to the signal, the controller  150  controls the power supply unit  123 , the valve switch  132  and the reaction gas supply unit  161  to stop the plasma treatment.  
         [0065]     As above, since it is enabled to remove the chlorine ions remaining at the substrate  109  formed of the polyimide film, this can prevent corrosion by residual ions, electrical failures such as ion migration or the like which are to be caused if the IC is connected with the use of ACF in a state with the chlorine ions remaining. Moreover, since the plasma treatment of the substrate  109  is stopped when the removal of the chlorine is completed as described hereinabove, it is possible to remove the chlorine ions remaining at the substrate  109  while the effect of oxygen ions on the substrate  109  is limited to a minimum. At the same time, since the substrate  109  is formed of polyimide, as discussed in the “BACKGROUND OF THE INVENTION”, the organic contaminant on the polyimide surface can also be removed by the oxygen radicals and the oxygen ions, and functional groups such as C═O, COOH and the like are formed on the surface, whereby the bonding strength between the substrate and the ACF is improved.  
         [0066]     The element within the substrate  109  that is controlled to emit from the substrate  109  is Br in the foregoing embodiments. However, the substrate surface treatment apparatuses  101  and  102  in the embodiments can be applied to the other corrosive elements. Similarly, although the element adhering to the substrate  109  is chlorine in the foregoing embodiments, the apparatuses  101  and  102  of the embodiments are applicable to the other elements as well.  
         [0067]     In each of the above embodiments, suppressing the emission of the element Br in the substrate  109 , and removing the chlorine adhering to the substrate  109  are described separately from each other. Needless to say, however, suppressing the emission of substrate constituents and removing impurities of the substrate may be carried out simultaneously by detecting a plurality of elements by the detecting device  140  such as the above emission spectroscopic analysis device  141 , the mass analyzer  142 , etc.  
         [0068]     Although the reaction gas injected into the reaction chamber  110  is argon and oxygen respectively in the embodiments described above, the present invention is not restricted to the specific kind of gas, and for instance, a mixed gas of argon and oxygen, hydrogen or nitrogen gas can be utilized. It is to be noted, however, that the reaction gas should be selected in some cases from a view point of a relationship with the substance to be processed by the surface treatment, because it is necessary to generate ions or the like effective for the substance to be processed by the surface treatment.  
         [0069]     In each embodiment, the grounded opposed electrode  122  is arranged in the reaction chamber  110 . The grounded reaction chamber  110  may be adapted to function by itself as an opposed electrode, and the opposed electrode  122  can be eliminated depending on the circumstances.  
         [0070]     Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.