JP2011098409A - Method and device of manufacturing mems device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an MEMS device capable of suppressing the occurrence of cracking in a substrate while suppressing, when forming a penetration part in the thickness direction of the substrate, the extension of a time required for forming the penetration part, and also to provide a device for performing the method of manufacturing the MEMS device. <P>SOLUTION: The MEMS device is manufactured by forming the penetration part extending through the front and rear surfaces of the substrate S by an etching plasma emitted onto the surface of the substrate S. When the penetration part is formed, the pressure of helium gas in a refrigerant space formed in the rear surface of the substrate S is lowered together with the energy of the etching plasma after the substrate S increased in temperature according to the intensity of the energy of the etching plasma is cooled by the helium gas serving as a cooling medium which is force-fed into the refrigerant space constituted of the rear surface of the substrate S and the recess 22a of a tray 22 on which the substrate S is placed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a MEMS device, and in particular, supplies an inert gas such as helium gas to one surface of a substrate to cool the substrate, and etches the other surface of the substrate to form the substrate. The present invention relates to a method for forming a penetrating portion and a MEMS device manufacturing apparatus that implements such a MEMS device manufacturing method.

  2. Description of the Related Art Conventionally, there is a demand for a technology for integrating elements and the like constituting such devices at high density due to restrictions on the mounting space of various devices. Among such integration technologies, micro electromechanical elements, so-called MEMS, in which mechanical element parts such as sensors and actuators and electrical circuits are integrated on a single semiconductor substrate, glass substrate, or substrate composed of an organic material. Technology development is actively underway. In manufacturing such a MEMS device, dry etching using a plasma composed of reactive gas, ions, radicals, or the like is frequently used for patterning a substrate itself such as a semiconductor substrate or a glass substrate as a constituent material thereof. Yes.

  In such dry etching, the reactive gas, ions, or radicals function as an etchant for etching the material to be etched, and etching is performed using a chemical reaction between the etchant and the material to be etched. Become. The chemical reaction referred to here is a process that proceeds when the semiconductor substrate, which is a material to be etched, collides with particles serving as an etchant contained in the etching plasma, and further electrons and the like contained in the etching plasma. . Therefore, the energy of the etching plasma to which it is exposed is continuously applied to the etching surface of the semiconductor substrate, and the temperature of the etching surface of the semiconductor substrate continues to rise as the etching proceeds.

  Here, it is known that the speed of dry etching that proceeds using a chemical reaction depends on the temperature of the substrate to be etched, that is, the reaction temperature. It is also well known that the etching rate increases as the temperature increases. Therefore, if the temperature of the substrate to be etched continues to rise as a result of etching as described above, it is natural that the substrate itself is thermally deformed due to this, and the etching amount varies. As a result, it becomes difficult to obtain a device having a desired shape. Therefore, as described in Patent Document 1, for example, an inert gas such as helium gas is supplied as a cooling medium to the surface opposite to the etching surface of the substrate, that is, the back surface, at a constant pressure, and thereby the heat of the substrate is reduced. By taking it away, the substrate is cooled so that the temperature is kept constant.

JP 2003-133286 A

By the way, in a MEMS having a structure in which mechanical elements and electronic circuits are integrated at a high density, the thickness of a substrate constituting the MEMS is used to form various elements included in the MEMS or to separate these various elements from each other. A number of through holes and through grooves are formed in the direction. The ratio of these through holes and through grooves to the main surface of the substrate increases as the integration of various elements increases, and often occupies about 50% of the total area of the substrate. Such a penetrating portion of the MEMS is generally formed by etching an oxide film, a nitride film or the like embedded in a semiconductor substrate, and the dry etching is widely used for the formation.

  On the other hand, during dry etching of such a substrate, an inert gas is supplied to the back surface for the purpose of keeping the temperature of the substrate constant, etching in the through hole formation region is completed, and the front and back surfaces of the substrate are separated by the through portion. These inert gases continue to be supplied until they penetrate. That is, even when dry etching is completed in which a large number of through portions are provided close to each other, the inert gas as described above is supplied to the substrate that is mechanically weakened by the through portions. . As a result, when the pressure of the inert gas supplied to the back surface of the substrate acts on the non-penetrating region between the penetrating parts, a crack occurs in a fine non-penetrating region that does not have sufficient rigidity to withstand the pressure. It will be. Further, if the penetrating portions are provided close to each other and continuously provided, the cracks occur over a plurality of non-penetrating regions, and consequently, the yield for manufacturing the MEMS device is also deteriorated. .

  One method for suppressing cracks generated in the substrate in this way is to reduce the rate at which the substrate is etched during dry etching, that is, the etching rate. If the etching rate is reduced, the amount of etchant per unit time that collides with the surface of the substrate can be reduced, that is, the amount of energy applied from the etching plasma to the surface of the substrate per unit time can be reduced. It becomes. Since the amount of heat received by the substrate per unit time is also reduced, the pressure of the inert gas supplied to the back surface of the substrate is necessarily low. Therefore, if the pressure of the inert gas is reduced to such a level that the non-penetrating region between the penetrating parts can mechanically endure even after the penetrating parts are formed, It is possible to suppress the occurrence of cracks. However, in this method, since it is necessary to reduce the etching rate in accordance with the mechanical rigidity of the non-penetrating region, it takes a long time to form the penetrating part. Although it is possible to suppress cracks occurring in the semiconductor device, the productivity of the MEMS device is deteriorated.

  The present invention has been made in view of the above circumstances, and the purpose thereof is to form a through-hole in the thickness direction of the substrate, while cracking the substrate while suppressing an increase in the time required for the formation. An object of the present invention is to provide a method of manufacturing a MEMS device capable of suppressing this, and an apparatus for carrying out the method of manufacturing the MEMS device.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a method of manufacturing a MEMS device in which a penetrating portion penetrating between a front surface and a back surface of a substrate is formed by etching plasma irradiated on the surface of the substrate, When the substrate is heated by an inert gas as a cooling medium that is pumped to the back surface of the substrate, the substrate is heated in accordance with the energy of the etching plasma, and then the substrate is heated on the back surface of the substrate. The gist is to reduce the pressure of the active gas together with the energy of the etching plasma.

The invention according to claim 6 is an apparatus for manufacturing a MEMS device, wherein a penetrating portion penetrating between a front surface and a back surface of a substrate is formed by etching plasma irradiated onto the surface of the substrate, An etching plasma irradiation unit that irradiates the surface with etching plasma, a substrate cooling unit that pumps an inert gas as a cooling medium to the back surface of the substrate, and the substrate that is heated according to the energy of the etching plasma. After cooling with an inert gas as a cooling medium pumped to the back surface of the substrate, the pressure of the inert gas on the back surface of the substrate is lowered together with the energy of the etching plasma, and the etching plasma irradiation unit The gist of the present invention is to include a control unit that controls the substrate cooling unit.

  In the above method and configuration, when a dry etching process is performed on the substrate to form a penetrating portion penetrating in the thickness direction, the etching rate of the substrate for the dry etching process is reduced by reducing the energy of the etching plasma in the middle. In addition, the pressure of the inert gas on the back surface of the substrate is reduced. For this reason, the mechanical rigidity of the substrate decreases as the depth of the penetration increases as the etching progresses. However, as the rigidity decreases, the energy of the etching plasma, more precisely, the plasma is supplied to the substrate. Then, the temperature rise of the substrate due to the energy converted into heat in the substrate is suppressed. Accordingly, the pressure of the inert gas on the back surface of the substrate, that is, the stress applied to the substrate is reduced, and it is possible to suppress the occurrence of cracks in the non-penetrating region between the penetrating portion and the other penetrating portions.

  In addition, since the pressure of the inert gas is lowered and the energy of the etching plasma is lowered in this way, even if the cooling efficiency of the substrate by the inert gas is lowered, the influence of the heating of the substrate, for example, between the substrates It is also possible to suppress etching variations due to temperature variations and scorching of various patterning used in the dry etching process. Furthermore, although the etching rate of the substrate is reduced during the formation of the through portion in this way, since the etching is performed at a higher etching rate before that, the entire through portion is formed. Prolonged time required can be suppressed.

  According to a second aspect of the present invention, in the MEMS device manufacturing method according to the first aspect of the present invention, a refrigerant space surrounded by a recess provided on a placement surface of a stage on which the substrate is placed and a back surface of the substrate. When the inert gas is pumped into the refrigerant space, the supply flow rate of the inert gas is adjusted so that the pressure of the inert gas in the refrigerant space becomes a target value, and the target is formed when the through portion is formed. Reducing the target value together with the energy of the etching plasma when the supply flow rate of the inert gas increases during the metering after a predetermined time has elapsed from the start of metering of the inert gas with respect to the value. The gist.

  The invention described in claim 7 is the MEMS device manufacturing apparatus according to claim 6, wherein the substrate cooling unit includes a recess provided on a mounting surface of a stage on which the substrate is mounted and a back surface of the substrate. And a metering unit for metering the supply flow rate of the inert gas so that the pressure of the inert gas in the refrigerant space becomes a target value while pumping the inert gas into the refrigerant space surrounded by The control unit, together with the energy of the etching plasma, when the supply flow rate of the inert gas increases during metering after a predetermined time has elapsed from the start of metering of the inert gas with respect to the target value. The gist is to lower the target value.

  The rigidity of the substrate decreases as the depth of the penetrating portion formed on the surface of the substrate increases as the dry etching progresses. As the rigidity of the substrate decreases, the substrate bends according to the distribution of the pressure of the inert gas supplied to the back surface of the substrate, and the supply flow rate of the inert gas is increased for the following reasons. It will be.

  For example, when the substrate is bent as described above, the volume of the refrigerant space formed by the substrate and the stage on which the substrate is placed, that is, the refrigerant space to which the inert gas is supplied increases. When the volume of the refrigerant space to which the inert gas is supplied is increased, the supply flow rate of the inert gas is increased in order to keep the pressure of the inert gas in the refrigerant space at the target value.

In addition, the positional consistency between the back surface of the substrate constituting the refrigerant space and the concave portion of the stage is also lowered by the above-described bending of the substrate, and the positional deviation between the concave portion provided on the mounting surface and the back surface of the substrate is reduced. In addition, a part of the inert gas that should normally be accommodated in the refrigerant space also leaks out of the refrigerant space. Then, in order to compensate for the inert gas leaking from the refrigerant space, the supply flow rate of the inert gas is increased.

  Furthermore, when only a part of the penetrating part penetrates in advance due to the variation in the progress of dry etching, the inert gas that should be accommodated in the refrigerant space leaks out from the refrigerant space through the part. Also become. Then, in order to compensate for the inert gas leaking from the refrigerant space, the supply flow rate of the inert gas is increased.

  As described above, when the substrate is bent as described above, the supply flow rate of the inert gas supplied to the refrigerant space is increased, and from the increase in the supply flow rate, the occurrence of the substrate deflection, that is, the decrease in the rigidity of the substrate is detected. can do.

  Therefore, when the amount of the inert gas supplied to the back surface of the substrate is increased as in the MEMS device manufacturing method according to claim 2 and the MEMS device manufacturing apparatus according to claim 7, dry etching is performed. If the substrate is bent due to a decrease in rigidity due to the progress of dry etching, the force that pushes the substrate toward the etching surface side is reduced. Can be reduced. That is, it is possible to suppress the force applied to the substrate due to the deformation due to the bending, and consequently to suppress the generation of cracks in the substrate.

  In the MEMS device manufacturing method according to claim 2 and the MEMS device manufacturing apparatus according to claim 7, the metering device after metering in after a predetermined time has elapsed since the start of metering of the inert gas. When the supply flow rate of the inert gas is increased, the target value is lowered together with the etching plasma energy. As described above, according to the correlation between the increase in the inert gas supply flow rate and the decrease in the rigidity of the substrate, it is possible to detect the timing immediately before the substrate can crack as the timing at which the inert gas supply flow rate increases. . However, normally, immediately after the start of metering of the inert gas, that is, immediately after the start of substrate cooling, the volume of the refrigerant space tends to fluctuate due to a rapid temperature change of the substrate due to etching plasma. Therefore, immediately after the start of metering of the inert gas, the supply flow rate of the inert gas also increases or decreases with the volume fluctuation of the refrigerant space. Therefore, if the inert gas supply flow rate is measured immediately after the start of the substrate cooling so as to detect the timing immediately before the substrate may crack, based on the increase in the inert gas supply flow rate, The timing at which the temperature change occurs is detected as the timing immediately before the substrate can crack. And since the energy of etching plasma is reduced at the timing immediately after the start of substrate cooling, there is a concern that it takes a lot of time to form the through-hole. On the other hand, as described in the second and seventh aspects of the invention, the increase in the inert gas supply flow rate after a predetermined time has elapsed from the start of the metering of the inert gas is caused by the inertness due to the reduction in the rigidity of the substrate. By increasing the gas supply flow rate, it is possible to avoid erroneously detecting an increase in the inert gas supply flow rate caused by other factors within the predetermined period as an increase in the inert gas supply flow rate due to a decrease in the rigidity of the substrate. become able to.

  According to a third aspect of the present invention, in the method for manufacturing a MEMS device according to the second aspect, the supply flow rate of the inert gas to the refrigerant space is monitored, and the adjustment of the inert gas to the target value is adjusted. The gist is to lower the target value together with the energy of the etching plasma when an increase in the supply flow rate of the inert gas is detected during metering after a predetermined time has elapsed from the start.

The invention according to claim 8 is the MEMS device manufacturing apparatus according to claim 7, further comprising an inert gas supply flow rate monitoring unit for monitoring the supply flow rate of the inert gas to the refrigerant space, and the control. The inert gas supply flow rate monitoring unit detects an increase in the inert gas supply flow rate during metering after a predetermined time has elapsed from the start of metering the inert gas with respect to the target value. Sometimes, the gist is to lower the target value together with the energy of the etching plasma.

  According to the above method and configuration, the flow rate of the inert gas supplied to the back surface of the substrate is monitored, and when an increase in the supply flow rate is detected, the rate of dry etching is reduced, and the back surface of the substrate The pressure of the inert gas is reduced. Therefore, it is possible to detect a decrease in the rigidity of the substrate and to reduce the pressure of the inert gas accordingly. By this, by carrying out the dry etching process without reducing the etching rate until just before the rigidity of the substrate is reduced, the time required for forming the through portion is more reliably suppressed, and thereafter By performing the dry etching process in a state where the pressure applied to the substrate is smaller, it is possible to prevent the substrate from being cracked when the through portion is formed.

  In the MEMS device manufacturing method according to the third aspect and the MEMS device manufacturing apparatus according to the eighth aspect, as in the inventions according to the second and seventh aspects, the start of metering of the inert gas is started. Since the increase in the inert gas supply flow rate is detected during the metering after a predetermined time has elapsed since the start time, the supply flow rate of the inert gas caused by other factors within the predetermined period is determined. It is possible to avoid erroneously detecting the increase as an increase in the supply flow rate of the inert gas due to the decrease in rigidity of the substrate.

  According to a fourth aspect of the present invention, in the MEMS device manufacturing method according to any one of the first to third aspects, the amount of the etchant contained in the etching plasma is monitored, and the pressure of the inert gas is set to the The gist is that the supply of the etching plasma is terminated when an increase in the amount of the etchant is detected after being lowered together with the energy of the etching plasma.

  The invention according to claim 10 is the MEMS device manufacturing apparatus according to any one of claims 6 to 9, further comprising an etchant amount monitoring unit that monitors the amount of the etchant included in the etching plasma, The gist of the present invention is that the controller ends the dry etching process when an increase in the amount of the etchant is detected by the etchant amount monitoring unit after lowering the pressure of the inert gas together with the energy of the etching plasma. .

  The dry etching process is performed by a chemical reaction between an etching plasma of molecules, ions, radicals, etc. contained in a reaction gas and a constituent material such as a substrate to be etched, such as silicon, silicon dioxide, or silicon nitride. Is to do. Therefore, when dry etching treatment is performed for the purpose of forming a through-hole in the substrate, when the formation of the through-hole is completed, the constituent material of the substrate to be etched does not exist, and the consumption of etching plasma is greatly increased. Get smaller. That is, if the amount of the etching plasma is monitored from the start to the end of the formation of the through portion, an increase in the etching plasma corresponding to the end of the formation of the through portion can be detected.

  Therefore, as in the method for manufacturing a MEMS device according to claim 4 and the apparatus for manufacturing a MEMS device according to claim 10, when the increase in the amount of etching plasma is detected, the formation of the penetrating portion is performed. If the dry etching process is completed, the through portion can be reliably formed while the substrate is hardly affected by the excessive dry etching process.

  According to a fifth aspect of the present invention, in the MEMS device manufacturing method according to any one of the first to fourth aspects, both the pressure of the inert gas and the energy of the etching plasma on the back surface of the substrate are reduced. In this case, the gist is to set the differential pressure between the front surface side and the back surface side of the substrate to “0”.

  As in the above method, if the differential pressure between the front surface side and the back surface side of the substrate is set to “0”, the force that pushes the substrate toward the etching surface side can be removed from the substrate, and cracks generated in the substrate can be further reduced. It becomes possible to suppress it reliably.

  The invention according to claim 9 is the MEMS device manufacturing apparatus according to claim 8, further comprising a storage unit that stores an etching rate at which the substrate is etched in association with energy of the etching plasma, and the control is performed. When an increase in the inert gas supply flow rate is detected by the inert gas supply flow rate monitoring unit, an etching rate corresponding to the energy of the etching plasma used before the detection, and the detection An etching rate corresponding to the energy of the etching plasma used later is extracted from the storage unit, and an etching processing time to be performed after the detection is t, which is required to form the through-hole in the substrate. The total etching amount is Ap, the etching rate before the detection and the processing performed at the etching rate. When the detection previous etching amount is calculated by the control unit and Aa based on the between, as its gist to determine the processing time based on t = (Ap-Aa) / v.

  When the increase in the supply flow rate of the inert gas is detected as described above, the value obtained by subtracting the etching amount before the detection from the total etching amount, that is, the thickness of the remaining film in the region to be the penetration portion is measured. If the remaining dry etching time is set according to the above, the substrate is only subjected to a simple process of setting the etching time without continuously monitoring the progress of the dry etching until the formation of the through portion is completed. The through portion can be formed while suppressing an excessive etching process.

  An eleventh aspect of the present invention is the MEMS device manufacturing apparatus according to any of the sixth to tenth aspects, wherein the substrate cooling unit mounts the first stage on which the substrate is mounted and the first stage. The first stage is a plurality of stages associated with each of the plurality of substrates, and the second stage is one common to the plurality of first stages. The gist is that it is a stage.

  When the through portion is formed in the substrate, plasma induced during the dry etching and various gases excited by the plasma flow into the stage mounting surface through the through portion. The plasma or excitation gas thus flowing into the mounting surface contains ions, radicals, and the like that are highly reactive with various substances, which react with the constituent materials of the stage and corrode the stage. When the stage is corroded in this way, the function of the stage is impaired as described below, and the stage must eventually be replaced. For example, if the stage mounting surface is directly exposed to plasma through the through-hole of the substrate, the etching proceeds on a part of the stage mounting surface, and the flatness of the mounting surface is impaired. The substrate is likely to be displaced on the mounting surface. If the etching is such that a bias potential is applied to the substrate through the stage, the plasma energy for the substrate is easily transmitted directly to the stage through the through-hole of the substrate, and abnormal discharge occurs on the stage mounting surface. It becomes easy.

In particular, if the energy of the etching plasma with respect to the substrate is changed during the period of irradiation with the etching plasma, such damage to the stage becomes remarkable for the following reason. That is, if the energy of the etching plasma with respect to the substrate is changed, the amount of etching on the substrate varies each time the energy of the etching plasma is changed. In order to reliably form the through portion, so-called over-etching, in which etching is performed with an etching amount larger than the etching amount required for forming the through portion, is generally performed. If the etching amount fluctuates as described above during the etching processing period, the over-etching amount naturally needs to be increased in order to compensate for the variation. For this reason, if the energy of the etching plasma for the substrate is changed, the amount of over-etching becomes large, and the opportunity for the plasma to flow into the back surface of the substrate through the penetrating portion inevitably increases.

  In this regard, as described above, if the substrate is placed on the second stage together with the first stage, a through-hole is formed in the substrate, through which the plasma, excitation gas, and the like are transferred to the substrate. Even if it flows into the rear surface side of these, these plasma and excitation gas react with the first stage and are consumed on the first stage. That is, it becomes possible to avoid the corrosion of the second stage due to the plasma and the excitation gas flowing in from the through portion.

The schematic block diagram which shows schematic structure of the MEMS device manufacturing apparatus which implements the dry etching process in the manufacturing method of the MEMS device which concerns on this Embodiment. The graph which shows the relationship between the supply flow rate of helium gas with respect to the manufacturing apparatus of a MEMS device, and the elapsed time after a dry etching process was started in the manufacturing apparatus of this MEMS device.

Hereinafter, an embodiment embodying a method for manufacturing a MEMS device according to the present invention will be described with reference to FIGS.
FIG. 1 shows, for example, penetration into a substrate to be processed by performing a dry etching process using a reactive gas containing ions, radicals, and the like, which is one step in the method for manufacturing a MEMS device according to the present embodiment. 1 shows a schematic configuration of a MEMS device manufacturing apparatus that forms a part. As shown in FIG. 1, the vacuum chamber constituting the device manufacturing apparatus has a chamber main body 10 having a multistage cylindrical shape with a lid, and a peripheral wall of the chamber main body 10 is a first cylinder that becomes a large diameter portion thereof. The portion 11 and the second cylindrical portion 12 loaded on the first cylindrical portion 11 and having a diameter smaller than that of the first cylindrical portion 11 are configured. An annular bottom plate 13 is attached to the lower surface opening of the first cylindrical portion 11 in the chamber body 10, and a top plate 14 is attached to the upper surface opening of the second cylindrical portion 12. It has been. And the exhaust pipe 15 provided with the vacuum exhaust part 16 which consists of a turbo-molecular pump etc. while being connected to the hole which penetrates this through the surrounding wall of the said 1st cylindrical part 11 is provided.

  At the opening of the bottom plate 13, a substrate stage 21, which is also formed in a cylindrical shape so as to seal the opening via an insulating member 13 a provided over the outer periphery, is attached to the first cylindrical portion 11. It is provided in such a form that it is accommodated in the substrate stage chamber 11a, which is an enclosed space. The substrate stage 21 has a recess 21 a that is recessed on the surface opposite to the opening side surface of the bottom plate 13, and opens to the bottom surface of the recess 21 a and the bottom plate side surface of the substrate stage 21. A helium gas channel 21b is provided.

On such a substrate stage 21, a tray 22 having a diameter smaller than that of the recess 21a and having a diameter larger than that of the recess 21a, on which the substrate S to be dry-etched, is placed. It is provided in a sealing manner. The tray 22 is formed of, for example, a metal such as aluminum, and has a plurality of openings that are open to a recess 22a that is recessed in the mounting surface of the substrate S, a bottom surface of the recess 22a, and a recess 21a of the substrate stage 21. Helium gas flow path 22b. The tray 22 is disposed on the substrate stage 21 so as to be removable and reattachable, and a plurality of substrates S are placed one by one on the upper surface thereof. The tray 22 can be replaced with a new tray 22 if it is corroded by plasma or the like leaking from the penetrating portion formed in the substrate S to the tray 22 side while the dry etching process for the substrate S is repeated a plurality of times. It is also a thing. That is, a plurality of trays are arranged on the single substrate stage 21 one by one, and a plurality of substrates S are placed on each of the plurality of trays 22. In addition, a metal mechanical chuck 23 that mechanically holds the position of the tray 22 by pressing the outer periphery of the substrate S placed on the upper surface of the tray 22 toward the tray side is provided on the upper portion of the tray 22. Yes.

  A substrate electrode 24 is provided in the substrate stage 21. The substrate electrode 24 has a substrate electrode high frequency power supply 25 for supplying, for example, a high frequency power of 13.75 MHz to the substrate S placed on the tray 22. Are connected via a capacitor 26. Note that the substrate electrode 24 has such a size and arrangement that the outer periphery thereof is closer to the center side of the substrate stage 21 than the outer periphery of the tray 22. Thereby, the high frequency power applied to the substrate electrode 24 is applied to the entire substrate S and is not applied to the outside of the substrate S, for example, the space between the substrate stage 21 and the mechanical chuck 23. .

  A vacuum pump 27 capable of evacuating the recess 21a is connected to the helium gas flow path 21b of the substrate stage 21 through the helium gas flow path 21b at the opening on the bottom plate 13 side. Yes. The pipe connecting the helium gas flow path 21b and the vacuum pump 27 includes a flow rate metering unit 28a for supplying an inert gas, for example, helium gas (He), to the pipe while metering, and the pipe is supplied into the pipe. A pressure gauge 28b for detecting the pressure of the helium gas is further connected. Further, both the flow metering unit 28a and the pressure gauge 28b are electrically connected to the helium gas control unit 28c. The helium gas control unit 28c receives a signal input corresponding to the pressure of the helium gas detected by the pressure gauge 28b, and based on this, the flow rate of helium gas to be set by the flow rate adjustment unit 28a, that is, the substrate S The flow rate of the helium gas is calculated so that the pressure in the space surrounded by the recess 22a becomes a target value, and a signal corresponding to the calculated value is output to the flow rate adjustment unit 28a.

  Further, on the outside of the peripheral wall of the second cylindrical portion 12, a high frequency antenna 31 for generating plasma in the plasma generation chamber 12 a partitioned by the second cylindrical portion 12 is doubled along the outer peripheral surface of the second cylindrical portion 12. The high frequency antenna 31 is connected to a high frequency power supply 32 for a high frequency antenna that supplies a high frequency voltage to the high frequency antenna 31. A magnetic field coil 41 including an upper coil 41T, a middle coil 41M, and a lower coil 41B is provided on the outer periphery of the high-frequency antenna 31. These magnetic field coils 41 are arranged between the upper coil 41T and the middle coil 41M. The two high-frequency antennas 31 are arranged in such a manner that one side is sandwiched and the other side is sandwiched between the middle coil 41M and the lower coil 41B. Of the three coils 41T, 41M, and 41B forming the magnetic field coil 41, the upper coil 41T and the lower coil 41B are supplied with the same current in the same direction and the same magnitude, and the middle coil 41M is supplied with these upper coils. And the electric current of the reverse direction is supplied to lower coil 41T, 41B. By supplying the current to each of the coils 41T, 41M, and 41B, an annular magnetic neutral line is formed in the vicinity of the middle coil 41M in the plasma generation chamber 12a. In addition, the second cylindrical portion 12 is generated while analyzing substances contained in the gas phase components in the plasma generation chamber 12a partitioned thereby, for example, the etching gas and excited species derived therefrom. A monitoring unit M for monitoring the amount is connected.

  On the surface of the top plate 14 on the side of the plasma generation chamber 12a, a gas for introducing various gases serving as an ion source or a radical source used in a dry etching process performed in the device manufacturing apparatus into the chamber body 10. An introduction port 51 is provided. In the gas inlet 51, a gas supply unit 52, which is a supply source of the various gases, is provided between two valves 53 and 55 for switching between inflow and non-inflow of gas, and between these valves 53 and 55. It is connected via a gas flow path 56 provided with a flow rate adjusting unit 54 for adjusting the flow rates of the various gases.

Further, the MEMS device manufacturing apparatus corresponds to the signal output from the pressure gauge 28b corresponding to the pressure of the helium gas detected by the pressure gauge 28b and the amount of etchant detected by the monitoring unit M. A control unit 60 to which a signal output from the monitoring unit M is input is provided. The control unit 60 sets conditions for dry etching processing performed in the MEMS device manufacturing apparatus based on these input signals. Further, the control unit 60 has a storage unit 60a, and the storage unit 60a has an output signal of the pressure gauge 28b and a formation state of the through-holes in the substrate S based on experiments performed in advance. The conditions of the dry etching process set in association with are stored. That is, the control unit 60 selects one of various conditions stored in the storage unit 60a based on signals input from the pressure gauge 28b and the monitoring unit M, and outputs an output signal corresponding to the selected condition to the substrate. By outputting to the electrode high-frequency power source 25, the high-frequency antenna high-frequency power source 32, the gas flow path 56, and the like, a dry etching process corresponding to the formation status of the through hole is performed in the MEMS device manufacturing apparatus. Yes.

In such a MEMS device manufacturing apparatus, in the dry etching process of the substrate S, first, the substrate S to be processed is loaded into a vacuum chamber from a loading port (not shown) and placed on the tray 22, and a mechanical chuck 23 is mechanically supported and held in position. In the plasma generation chamber 12a, for example, gas from the gas supply unit 52 for supplying octafluoropropane (C ₃ F ₈ ), octafluorocyclobutane (C ₄ F ₈ ), or the like is flow-regulated. Supplied in a state metered to a predetermined amount by the unit 54. Next, when a current is supplied to the magnetic field coil 41, an annular magnetic neutral line, that is, a region where the magnetic field is “0” is formed in the plasma generation chamber 12a into which the etching gas is thus introduced. Accordingly, electric power is supplied from the high-frequency power source 32 for the high-frequency antenna to the high-frequency antenna 31, whereby an electric field is formed in the plasma generation chamber 12 a where the annular magnetic neutral line is formed. A discharge plasma derived from an etching gas such as cyclobutane fluoride is generated. That is, the etching gas is turned into discharge plasma, and excited species such as ions and radicals are generated. Thereafter, a predetermined high-frequency voltage is applied from the substrate electrode high-frequency power supply 25 to the substrate electrode 24 in the substrate stage 21 provided under the tray 22 on which the substrate S is placed. As a result, the excited species derived from the etching gas flies to the substrate S by the bias voltage of the substrate S placed on the upper surface of the tray 22, and enters the substrate S as an etchant and makes it have a predetermined shape. Etch into. That is, in the present embodiment, the chamber main body 10, the gas flow path 56 for introducing the etching gas into the chamber main body 10, the magnetic field coil 41, the high frequency antenna 31, and the high frequency power supply for the high frequency antenna that applies a high frequency voltage thereto. 32 functions as an etching plasma irradiation unit that irradiates the surface of the substrate S with etching plasma.

  Here, when the excited species derived from the etching gas is irradiated onto the surface of the substrate S, the energy of the etching plasma passes through the contact between the particles constituting the plasma and the substrate surface, and the substrate S according to the amount of energy of the plasma. The amount of heat is converted to increase the temperature of the substrate S. Such plasma characteristic values such as the plasma potential of the etching plasma viewed from the substrate S and the density of the plasma drawn into the substrate S can be handled as an index of the energy of the etching plasma. The characteristic values such as the plasma potential of the etching plasma and the density of the plasma drawn into the substrate S include the amount of power supplied to the high-frequency antenna 31, the amount of current supplied to the magnetic field coil 41, and the power supplied to the substrate electrode 24. It can be increased or decreased depending on the amount.

For example, when the amount of electric power supplied to the substrate electrode 24 increases, the potential of the etching plasma viewed from the substrate S increases, so that the speed of particles flying toward the substrate S increases. As a result, the amount of heat given to the substrate S from such particles generally increases, that is, the energy of etching plasma on the substrate S also increases. On the other hand, when the amount of electric power supplied to the substrate electrode 24 is lowered, the potential of the etching plasma viewed from the substrate S is lowered, so that the velocity of particles flying toward the substrate S is lowered. As a result, the amount of heat given to the substrate S from such particles is generally small, that is, the energy of the etching plasma for the substrate S is also low. When the amount of power supplied to the substrate electrode 24 is increased or decreased in this way, the speed of particles flying toward the substrate S is increased or decreased, and the energy of etching plasma with respect to the substrate S is increased or decreased. Various conditions relating to the dry etching process, that is, the flow rate of the etching gas, the current value supplied to the magnetic field coil 41, the high-frequency power value applied to the high-frequency antenna 31, the high-frequency power value applied to the substrate S, etc. Is set based on the condition selected by the control unit 60.

  Further, during such a dry etching process, helium gas is supplied from the flow rate adjustment unit 28 a to the helium gas flow path 21 b of the substrate stage 21. The supplied helium gas is formed between the concave portion of the tray 22 and the substrate S via the helium gas flow path of the substrate stage 21, the concave portion 21 a of the substrate stage 21, and the helium gas flow path 22 b of the tray 22. Supplied to the refrigerant space. That is, the temperature rise of the substrate S is suppressed by the helium gas stored in the refrigerant space, so that the temperature is kept constant. At this time, the amount of helium gas supplied to the refrigerant space is controlled by the helium gas control unit 28c so that the pressure of the helium gas in the refrigerant space becomes a predetermined value, that is, a target value.

  Specifically, an output signal corresponding to the pressure detected by the pressure gauge 28b is input to the helium gas control unit 28c. Next, the helium gas control unit 28c calculates the flow rate of the helium gas to be supplied from the flow rate adjustment unit 28 based on the signal thus input, and outputs a signal corresponding thereto. Then, helium gas having a flow rate corresponding to the output signal is supplied from the flow rate adjusting unit 28a. That is, the flow rate of helium gas supplied to the refrigerant space is adjusted by so-called feedback control so as to satisfy the target value. Thus, in the present embodiment, the pressure gauge 28b functions as an inert gas supply flow rate monitoring unit that monitors the supply flow rate of the helium gas during the metering of the helium gas by the helium gas control unit 28c. Further, the flow rate adjustment unit 28a functions as a substrate cooling unit that pumps helium gas as a cooling medium. In addition, the pressure gauge 28b and the flow rate adjustment unit 28a also function as a adjustment unit that adjusts the supply flow rate so that the pressure of the helium gas in the refrigerant space becomes a target value. The supply flow rate of the helium gas is a flow rate of helium gas supplied from the flow rate adjustment unit 28a to the refrigerant space side per unit time, for example, per minute.

  In addition, when such dry etching processing is performed, a gas phase component in the plasma generation chamber 12a of the chamber body 10, in other words, an etching gas, an excited species derived from the etching gas, or a constituent material of the substrate S during dry etching. A mixture of a product and the like resulting from the reaction between and the etchant is introduced into the monitoring unit M. In the monitoring unit M, components contained in the gas phase are analyzed by, for example, emission spectroscopic analysis. That is, in the present embodiment, the monitoring unit M functions as a gas phase, in other words, an etchant amount monitoring unit that monitors the amount of etchant contained in the etching plasma.

Here, when forming the penetration part by dry etching, the etchant contained in the gas phase continues to be consumed from the start to the end of the formation of the penetration part. Therefore, when the conditions for dry etching are kept the same and the substrate S is etched, its content in the gas phase changes by a predetermined amount obtained by subtracting the amount consumed by etching from the amount of etchant generated. Will do. Similarly, the amount of the product obtained by etching the substrate S also changes by a predetermined amount. On the other hand, when the formation of the through portion is completed, the etchant consumption reaction due to the dry etching process, that is, the etching reaction of the substrate S does not occur at the same time. That is, when the formation of the penetrating portion is completed, an increase in the etchant contained in the gas phase and a decrease in the product due to etching are detected. Therefore, when the increase in the etchant or the decrease in the product is detected in the monitoring unit M, in other words, when the formation of the through portion is completed, when the dry etching process for forming the through portion is completed. It can be. As described above, an increase in the amount of etching plasma, particularly an etchant, is detected by the monitoring unit M, and a signal corresponding to the detected amount is input to the control unit 60. If the end of the dry etching process for forming the portion is selected, it is possible to realize a state in which the through portion is reliably formed but the influence on the substrate S due to the excessive dry etching process is hardly caused. Become.

  When, for example, a through-hole is formed in the substrate S by the dry etching process on the substrate S as described above, the plasma induced during the dry etching process and various plasma gases are transmitted through the through-hole to the substrate stage 21. Flows into the substrate mounting surface. In this way, the plasmad gas that has flowed into the substrate mounting surface contains ions, radicals, and the like that are highly reactive with various substances, and this reacts with the constituent material of the substrate stage 21 to corrode the substrate stage 21. Will be. If the substrate stage 21 is corroded in this way, the function of the substrate stage 21 is impaired as described below, and the substrate stage 21 must eventually be replaced.

  For example, when the substrate placement surface of the substrate stage 21 is directly exposed to plasma through the penetration portion of the substrate S, etching proceeds on a part of the substrate placement surface of the substrate stage 21. The flatness of the substrate S is impaired, and the positional deviation of the substrate S is likely to occur on the substrate mounting surface. Further, in the etching mode in which a bias potential is applied to the substrate S through the substrate stage 21, the plasma energy for the substrate S is easily transmitted directly to the substrate stage 21 through the through portion of the substrate S. Abnormal discharge is likely to occur on the substrate mounting surface.

  In particular, during the period of irradiation with etching plasma, for example, depending on the progress of the etching process on the substrate S, or the substrate S is made of a multilayer film including films made of different forming materials, and etching of a film made of a certain forming material If the energy of the etching plasma with respect to the substrate S is changed by, for example, shifting from etching to etching of a film made of another type of forming material, the damage to the substrate stage 21 becomes significant for the following reasons. That is, by changing the etching plasma energy for the substrate S, the amount of etching in the substrate S varies each time the etching plasma energy is changed. In order to reliably form the through portion in the substrate S, so-called over-etching is generally performed in which etching is performed with an etching amount larger than the etching amount required for forming the through portion. If the etching amount fluctuates as described above during the etching processing period, the variation in the etching amount within the same substrate surface becomes large. Since the over-etching is generally performed for the purpose of compensating for the variation in the substrate surface as described above, when the variation becomes large, the amount of over-etching for compensating for the variation is also natural. It needs to be bigger. For this reason, if the energy of the etching plasma for the substrate S is changed, the amount of such over-etching increases, and the opportunity for the plasma to flow into the back surface of the substrate S through the penetrating part inevitably increases.

  In this regard, as in the present embodiment, if the substrate S is placed on the substrate stage 21 together with the tray 22, a through-hole is formed in the substrate S, and the plasma, excitation gas, and the like are passed through the substrate. Even if it flows into the back side, these plasma and excitation gas are consumed on the tray 22 by reacting with the tray 22. That is, it becomes possible to avoid the corrosion of the substrate stage 21 caused by the plasma and the excitation gas flowing from the through portion.

The tray 22 placed on the substrate stage 21 is provided with a recess 22a that opens on the substrate placement surface side, so that the space between the substrate placement surface of the tray 22 and the back surface of the substrate S is between. The helium gas supplied to the refrigerant space formed in is stored in the recess 22a. That is, the amount of helium gas used for cooling the substrate S is increased by the amount of the concave portion 22a formed, so that the cooling efficiency is improved. Further, since the substrate stage 21 also has a recess 21a that opens to the tray mounting surface, the helium gas supplied from the helium gas flow path 21b of the substrate stage 21 to the cooling space enters the recess 22a. Will also be stored. As a result, the refrigerant space is expanded by, for example, an increase in the substrate temperature due to the dry etching process, that is, even if the substrate S is deformed so as to warp on the side opposite to the tray 22, The helium gas corresponding to the reduced pressure of the helium gas is supplemented by the helium gas stored in the recess 21a. Therefore, the concave portion 21a is not formed in the substrate stage 21, and the pressure decrease of the helium gas due to the deformation of the substrate S is more quickly compensated than when the helium supply from the flow metering unit 28a is compensated. Therefore, it is possible to suppress a decrease in the cooling efficiency of the substrate S.

In the MEMS device manufacturing apparatus, by performing the substrate S dry etching process in the above-described manner, openings are formed on the etching surface of the substrate S and the opposite surface, in other words, on the upper surface and the lower surface of the substrate S. A penetrating part is formed. A MEMS device manufactured by the MEMS device manufacturing apparatus generally has a structure in which mechanical elements and electronic circuits are integrated with high density. Therefore, in order to form various elements included in this element or to separate these various elements from each other, the area of the through portion and the through groove in the substrate S constituting the MEMS device often accounts for about 50%. That is, the substrate S is provided with a plurality of through portions, and these through portions are provided close to each other. Such a penetrating portion is formed by scraping a region of an insulating film made of silicon dioxide (SiO ₂ ) or the like previously embedded in the substrate S with an etchant.

  Here, as described above, when dry etching the substrate S, helium gas is supplied to the back surface of the substrate S for the purpose of cooling the substrate and keeping the temperature constant. The supply of the helium gas as the cooling gas is continued until the etching of the insulating film which is the formation region of the through portion is completed and the front surface and the back surface of the substrate are penetrated by the through portion. That is, helium gas is supplied to the substrate S that is mechanically weakened by the through-holes even when the dry etching is completed in which many through-holes are provided close to each other. As a result, when the pressure of the helium gas supplied to the back surface of the substrate S acts on the non-penetrating region between the penetrating portions, a crack is generated in a fine non-penetrating region that does not have sufficient rigidity to withstand the pressure. It will be. In addition, if the penetrating portions are provided close to each other and continuously provided, the cracks may occur over a plurality of non-penetrating regions.

  Therefore, in the present embodiment, depending on the progress of the dry etching process for the substrate S, particularly the progress of the through-hole forming process, it is supplied to the refrigerant space formed by the back surface of the substrate S and the recess 22a of the tray 22. By changing the amount of helium gas, the substrate S is prevented from being cracked. More precisely, the flow rate of the helium gas supplied to the refrigerant space, in other words, the pressure of helium gas in the refrigerant space is changed in accordance with the rigidity of the substrate S that decreases as the dry etching process proceeds.

Next, dry etching processing performed in the MEMS device manufacturing apparatus, in particular, conditions for dry etching processing for forming a through-hole in the substrate S, and the refrigerant when the dry etching processing is performed under the conditions A change in the flow rate of the helium gas supplied to the space will be described in detail with reference to FIG. 2 and Tables 1 to 3. In the dry etching process performed in the MEMS device manufacturing apparatus, a. A high-speed etching step, b. Helium dump process, c. The low-speed etching process and these three processes are sequentially performed. Tables 1 to 3 show examples of the etching conditions in each step. Also, FIG. It is a figure which shows the flow volume of helium gas in a high-speed etching process, and shows the relationship between the elapsed time after starting the dry etching process with respect to the board | substrate S, and the flow volume per unit time of the helium gas supplied to the said refrigerant | coolant space. ing.

(A. High-speed etching process)
First, in order to start the formation of the penetrating portion, the control unit 60 selects a dry etching condition corresponding to this from the conditions stored in the storage unit 60a. That is, the conditions shown in Table 1 are selected, and the conditions relating to the dry etching process performed in the MEMS device manufacturing apparatus are set as the conditions in Table 1. Next, the control unit 60 outputs a signal corresponding to this to the gas flow path 56, the substrate electrode high-frequency power source 25, the high-frequency antenna high-frequency power source 32, and the like to execute a high-speed etching process. As shown in Table 1, the dry etching process at the start of the through-hole formation is performed by using, for example, propane octafluoride as an etching gas for the silicon dioxide region embedded in advance in the substrate S made of silicon (Si). with _(C 3 _{F 8)} and the argon (Ar) is carried out under the following conditions.

こうした高速エッチング工程が開始される前では、トレイ２２に基板Ｓが載置されておらず、上記冷媒空間がプラズマ発生室１２ａに開放された状態、すなわち真空状態となっている。この初期状態からドライエッチング処理が開始されると、まずトレイ２２に基板Ｓがセットされ、該基板Ｓによって冷媒空間が閉塞される。そして冷媒空間の圧力が目標値の近傍へ昇圧される態様で、ヘリウムガスの調量が開始される。そのため、こうした高速エッチング工程が開始されるときには、同図２に示されるように、真空状態にあった冷媒空間の圧力を目標値の近傍にまで昇圧するべく、１０ｓｃｃｍを超えるといった極めて高い流量のヘリウムガスが冷媒空間へと供給されることとなる。そしてドライエッチング開始時に大流量のヘリウムガスが供給されると、つまり冷媒空間の圧力が目標値の近傍にまで昇圧されると、その後、冷媒空間における急激な圧力変動が抑えられつつ、該冷媒空間の圧力がさらに目標値に近付けられる態様で、ヘリウムガスの調量が実行される。

Before such a high-speed etching process is started, the substrate S is not placed on the tray 22, and the refrigerant space is open to the plasma generation chamber 12a, that is, a vacuum state. When the dry etching process is started from this initial state, the substrate S is first set on the tray 22 and the coolant space is closed by the substrate S. Then, helium gas metering is started in such a manner that the pressure in the refrigerant space is increased to the vicinity of the target value. Therefore, when such a high-speed etching process is started, as shown in FIG. 2, helium having an extremely high flow rate exceeding 10 sccm to increase the pressure of the refrigerant space in a vacuum state to the vicinity of the target value. Gas will be supplied to the refrigerant space. When a large flow of helium gas is supplied at the start of dry etching, that is, when the pressure in the refrigerant space is increased to a value close to the target value, abrupt pressure fluctuations in the refrigerant space are then suppressed and the refrigerant space is suppressed. The metering of helium gas is performed in such a manner that the pressure of is further brought closer to the target value.

  By adjusting the amount of helium gas, when the timing T1, that is, 30 seconds have elapsed from the start of dry etching, the supply flow rate that has exceeded 10 sccm is reduced to about 1.5 sccm. Such a decrease in the supply flow rate is due to the fact that the pressure of the helium gas in the refrigerant space has reached the vicinity of the target value due to the supply of helium gas at the start of etching. Until the pressure of the refrigerant space reaches the vicinity of the target value in this way, the cooling action of the substrate S by the helium gas is not sufficiently exerted, so the temperature of the substrate S rapidly increases. .

  Next, from the timing T1 to the timing T2, that is, 35 seconds after the timing T1 (65 seconds after the start of dry etching), the supply flow rate of the helium gas gradually increases to 1.5 sccm to 2 sccm. The increase in the supply flow rate is considered to be because the substrate S is thermally deformed as the substrate temperature rapidly increases. For example, when the substrate S is suddenly thermally deformed, the substrate S may be deformed so as to warp on the side opposite to the tray 22, thereby expanding the refrigerant space. Further, when the substrate S is suddenly thermally deformed, the displacement of the substrate S with respect to the tray 22 is likely to occur, and the adhesion between the substrate S and the tray 22, that is, the sealing performance of the refrigerant space may be reduced. . Then, it is considered that the supply flow rate of helium gas temporarily increases due to the phenomenon such as the expansion of the refrigerant space and the decrease in the sealing performance of the refrigerant space. In the period in which the supply flow rate of helium gas is once increased, the pressure of the refrigerant space has already reached the vicinity of the target value, so that the cooling action of the substrate S by the helium gas is sufficiently exerted, and the substrate The temperature rise of S is also gradually suppressed.

  Subsequently, the increase in the supply flow rate is also terminated at timing T2, and the supply of helium gas is continued from timing T2 to timing T3, that is, 30 seconds after timing T2 (95 seconds after the start of dry etching). The flow rate gradually decreases. In addition, at this time, the supply flow rate is about 2 sccm at the timing T2, and the supply flow rate at the timing T3 is 1.2 sccm. Therefore, the timing is higher than the absolute value of the increase rate of the supply flow rate from the timing T1 to the timing T2. The absolute value of the decrease rate of the supply flow rate from T2 to timing T3 is larger. Thus, the rapid decrease from the timing T2 to T3 suppresses rapid thermal deformation of the substrate temperature due to the cooling action of the helium gas, and the expansion of the refrigerant space due to the thermal expansion of the substrate S as described above converges. This is probably because the sealing performance of the space has been improved.

When such a rapid decrease from timing T2 to timing T3 ends, the supply flow rate of helium gas becomes monotonous from timing T3 to timing T4, that is, 430 seconds after timing T3 (525 seconds after the start of dry etching). Decrease. In addition, during this period, the supply flow rate only decreases from 1.2 sccm to 0.3 sccm, that is, the absolute value of the decrease rate of the supply flow rate per second is 2.1 × 10 ⁻³ sccm / sec. Yes, it is sufficiently smaller than 3.2 × 10 ⁻² sccm / sec, which is the absolute value of the decrease rate of the same supply flow rate from timing T2 to timing T3, and the supply flow rate of helium gas supplied to the refrigerant space is stable It can be said that they are doing. This is because the pressure of the helium gas in the refrigerant space is roughly the target value, and the thermal deformation of the substrate S has converged, that is, the pressure in the refrigerant space is closer to the target value than from the timing T1 to the timing T3, and This is probably because the size of the refrigerant space and the airtight state have been maintained.

If the stable supply of helium gas continues in this way, the helium gas supply flow rate will eventually increase at timing T4 and increase from 0.3 sccm to 2.6 sccm. When such a steep increase in the supply flow rate is detected by the pressure gauge 28b and a signal corresponding thereto is input to the control unit 60, the helium is discharged at timing T5, that is, 530 seconds after the start of dry etching. The dry etching process under the conditions shown in Table 1 including the gas supply is stopped, and the high-speed etching process is completed. By the way, during the period from the timing T1 to the timing T2, it increases only from 1.5 sccm to 2 sccm, and the elapsed time from the timing T1 to the timing T2 is 25 seconds. It is only about 2.0 × 10 ⁻² sccm / sec. On the other hand, the increase rate of the helium gas from the timing T4 to the timing T5 at which the dry etching process is forcibly stopped is 2.3 × 10 ⁻¹ sccm / sec, and the increase rate from the timing T1 to the timing T2 It is understood that it is 10 times more than that. Such an increase in the supply flow rate is considered to be due to the following change in the mechanical structure of the substrate S.

  That is, as the etching surface of the substrate S, in other words, the depth of the through portion formed on the surface of the substrate S increases, the rigidity of the substrate S decreases. As the rigidity of the substrate S decreases, the breaking stress, which is the maximum stress that the substrate S can withstand without being broken, also decreases. In other words, when the rigidity of the substrate is lowered until the pressure in the refrigerant space becomes close to the destructive stress, the substrate S bends while projecting from the back surface to the surface. Accordingly, the volume of the refrigerant space formed by the substrate S and the concave portion 22a of the tray 22 on which the substrate S is placed, that is, the refrigerant space supplied with the helium gas is increased. When the volume of the refrigerant space to which helium gas is supplied is increased, the supply flow rate of helium gas is increased in order to maintain the pressure of the helium gas in the refrigerant space at the target value as described above.

  On the other hand, when the penetrating part penetrates in advance in a part of the substrate surface due to the progress variation of the dry etching process in the same substrate surface, this also is the helium gas that should be accommodated in the refrigerant space. A part will also leak from the refrigerant space through the penetrating part. Then, in order to compensate for the helium gas leaking from the refrigerant space, the supply flow rate of helium gas is increased.

  As described above, whether the penetration portion in the substrate S is deep or the penetration portion is formed in a part of the surface of the substrate S, the helium pressure acting on the substrate S causes the destruction of the substrate S. When the stress approaches, the supply flow rate of helium gas supplied to the refrigerant space increases sharply. In other words, whether or not the rigidity of the substrate S at that time is critical for generating cracks in the substrate S is detected from the steep increase in the flow rate of helium gas supplied to the refrigerant space. A sign of occurrence can be detected.

The increase in the supply flow rate of helium gas here has an increase rate of about 10 ⁻¹ sccm / sec as described above, and the monotonous decrease in the supply flow rate of helium gas as described above, for example, until just before that. The helium gas supply flow rate is stabilized, that is, the fluctuation rate is about 10 ⁻³ sccm / sec. Further, the behavior of the helium gas supply flow rate from the timing T1 to the timing T4 is an example, and the refrigerant space formed by the substrate S and the concave portion 22a of the tray 22 is reduced by the thermal expansion of the substrate S, for example. Variations in the manner are also conceivable. In this case, it is considered that the change in the supply flow rate of helium gas from the timing T1 to the timing T2 has a decreasing tendency rather than an increasing tendency. Alternatively, even when the change in the supply flow rate of the helium gas from the timing T1 to the timing T2 has an increasing tendency as described above, it is assumed that the increase timing is not once but a plurality of times. The Further, the tendency seen from the timing T3 to the timing T4, that is, the stable behavior of the helium gas before the steep increase in the supply flow rate of the helium gas has only the decreasing tendency as described above. In some cases, there is a tendency to increase.

  In any case, the sudden increase in the supply flow rate of the helium gas follows the stable behavior of the supply flow rate of the helium gas, and the increase compared to other increases or decreases seen before. The speed is limited to about 10 times.

In addition, in the present embodiment, the increase in the supply flow rate of helium gas, which is the end timing of such a high-speed etching process, means that a predetermined time has elapsed since the start of metering of helium gas simultaneously with the start of the dry etching process. Later, it is limited to those detected while metering the helium gas. The predetermined time is the time until the expansion of the refrigerant space due to the temperature rise of the substrate S as described above converges, the sealing performance of the refrigerant space is continuously improved, or is continuously stable. In other words, it is set as the time until the aspect of the supply flow rate of helium gas (decrease per unit time, etc.) remains unchanged in time.

  For example, the predetermined time is determined by the constituent material of the substrate S and the energy of the etching plasma that raises the temperature of the substrate S. This is because the thermal expansion coefficient of the substrate S varies depending on the constituent material of the substrate S, and the difference in the degree of thermal deformation of the substrate S, in other words, the degree of expansion of the refrigerant space and the sealing property of the refrigerant space. This is because the degree of variation is also different. For example, a substrate made of a material having a smaller coefficient of thermal expansion has a smaller deformation due to its temperature rise, and therefore the degree of expansion of the refrigerant space partitioned by this is also reduced. On the other hand, since the temperature rise degree of the substrate S is defined by the energy of the etching plasma, the degree of thermal deformation of the substrate S is also defined by the energy of the etching plasma. Such thermal deformation generally increases as the degree of temperature rise of the substrate S increases, that is, as the energy of the etching plasma varies greatly. Therefore, the predetermined time is set according to the degree of thermal deformation of the substrate S defined by the thermal expansion coefficient and the energy of the etching plasma. Further, the larger the degree of thermal deformation of the substrate S defined by the thermal expansion coefficient and the degree of temperature rise of the substrate S, the more it takes for the increase and decrease in the supply flow rate of helium gas supplied to the refrigerant space to converge. Since the time becomes longer, the predetermined time is also set longer.

  In the present embodiment, the time from the start of the dry etching process shown in FIG. 2 to the timing T3 is set as the predetermined time. Further, even if this time T3 is reached, for example, an increase in the amount of helium gas supplied between the timing T1 and the timing T2 is detected by the pressure gauge 28b and the output signal is input to the controller 60. In the control unit 60, it is not determined that the formation of the through hole has progressed and the rigidity of the substrate S has decreased.

  As described above, in this embodiment, a period during which the increase in the supply flow rate of the helium gas may occur as a predetermined time due to other factors other than the decrease in the rigidity of the substrate S is set as the predetermined time, and the helium gas detected after the predetermined time has elapsed. The increase in the supply flow rate is increased due to the decrease in the rigidity of the substrate S. This avoids erroneously detecting an increase in the supply amount of helium gas due to the above other factors as an increase in the supply amount of helium gas due to a decrease in the rigidity of the substrate S, that is, the end timing of the high-speed etching process.

(B. Helium dump process)
When the increase in the helium gas supply flow rate at timing T4 shown in FIG. 2 is detected by the pressure gauge 28b, an output signal corresponding to the detected value is input to the control unit 60. In this way, the control unit 60 to which the signal is input determines that the rigidity of the substrate S has decreased due to the progress of the formation of the penetrating part, and the dry etching conditions corresponding to this are stored in the storage unit 60a. It is selected from the inside. That is, the conditions shown in Table 2 are selected, and the conditions related to the dry etching process performed in the MEMS device manufacturing apparatus are changed from the conditions in Table 1 to the conditions in Table 2. Next, the control unit 60 outputs a signal corresponding thereto to the gas flow path 56, the substrate electrode high-frequency power source 25, the high-frequency antenna high-frequency power source 32, and the like, and executes the helium dump process.

上記表２に示されるように、ＭＥＭＳデバイス製造装置には、八フッ化プロパンのみからなるエッチングガスが導入されるものの、上記高周波アンテナ３１及び基板電極２４には高周波電圧が印加されない。そのため、この表２に示される条件が設定されている間は、上記基板Ｓのエッチング、換言すれば貫通部の形成は進行しない。つまり、エッチングプラズマが誘起されないため、上記監視部Ｍによっては、エッチングガス由来のエッチャントやエッチング反応による生成物等が検出されない。

As shown in Table 2, the MEMS device manufacturing apparatus is introduced with an etching gas composed only of octafluoropropane, but no high-frequency voltage is applied to the high-frequency antenna 31 and the substrate electrode 24. Therefore, while the conditions shown in Table 2 are set, the etching of the substrate S, in other words, the formation of the through portion does not proceed. That is, since etching plasma is not induced, the monitoring unit M does not detect an etchant derived from an etching gas, a product due to an etching reaction, or the like.

  When the conditions in Table 2 are changed, the space between the back surface of the substrate S and the concave portion 22a of the tray 22 is filled so that the pressure of the helium gas supplied to the refrigerant space is “0”. The helium gas filled in the helium gas flow path 22 b of the tray 22, the recess 21 a of the substrate stage 21, and the helium gas flow path 21 b of the substrate stage 21 are evacuated by the vacuum pump 27. At this time, the flow rate of the helium gas to be supplied is set to “0” in the flow rate metering unit 28 a that performs helium gas metering.

  As described above, when the occurrence of a crack in the substrate S or a sign of the crack is detected, the flow rate of the helium gas supplied to the back surface of the substrate S is set to “0”. By making the differential pressure of “0” or a pressure close to “0”, it is possible to remove the force that pushes the substrate S from the back surface to the front surface side, which is the etching surface, and more reliably generate cracks in the substrate S. Can be suppressed.

(C. Low speed etching process)
As described above, after the helium gas exhaust process is performed for 30 seconds, the control unit 60 selects the dry etching conditions corresponding to the helium gas from the conditions stored in the storage unit 60a. That is, the conditions shown in Table 3 are selected, and the conditions relating to the dry etching process performed in the MEMS device manufacturing apparatus are changed from the conditions in Table 2 to the conditions in Table 3. Next, the control unit 60 outputs a signal corresponding thereto to the gas flow path 56, the substrate electrode high-frequency power source 25, the high-frequency antenna high-frequency power source 32, and the like to execute a low-speed etching process.

上記表３に示されるように、ＭＥＭＳデバイス製造方法には、先の表２に示される条件と同様、八フッ化プロパンのみからなるエッチングガスが導入される。このエッチングガスは、先の表１に示される条件よりもその流量が低減されており、詳細には６２．５％とされる。また、先の表１に示される条件では、エッチングガスの総流量が１００ｓｃｃｍであるのに対し、上記表３に示される条件では、その１／４の２５ｓｃｃｍとされている。これに伴い、上記チャンバ本体１０内のガス圧である作動圧力も表１に示される条件の１／４である０．２５Ｐａとなる。また、高周波アンテナ３１及び基板電極２４に印加される電力も表１に示される条件から低減され、このうち高周波アンテナへの印加電力は５５％程度に、他方、基板電極２４への印加電力は１１％程度にまで低減される。さらに、冷却用のヘリウムガスの圧力は、先の表２に示される条件から引き続き「０」のままに維持される。

As shown in Table 3 above, in the MEMS device manufacturing method, an etching gas composed of only octafluoropropane is introduced, as in the condition shown in Table 2 above. The flow rate of this etching gas is lower than the conditions shown in Table 1 above, specifically 62.5%. Further, the total flow rate of the etching gas is 100 sccm under the conditions shown in Table 1 above, whereas it is ¼ of 25 sccm under the conditions shown in Table 3 above. Along with this, the operating pressure, which is the gas pressure in the chamber body 10, also becomes 0.25 Pa, which is ¼ of the conditions shown in Table 1. Further, the power applied to the high-frequency antenna 31 and the substrate electrode 24 is also reduced from the conditions shown in Table 1. Among these, the power applied to the high-frequency antenna is about 55%, while the power applied to the substrate electrode 24 is 11%. %. Further, the pressure of the cooling helium gas is maintained at “0” from the conditions shown in Table 2 above.

  By carrying out the dry etching process under the conditions shown in Table 3, when the formation of the penetrating part is completed, the monitoring part M detects an increase in the amount of etchant contained in the gas phase, that is, in the etching plasma. When a signal corresponding to the detected value is output from the monitoring unit M to the control unit 60, the control unit 60 determines that the etching process is finished. A signal corresponding to the completion of such dry etching is output to the substrate electrode high frequency power supply 25, the high frequency antenna high frequency power supply 32, the gas flow path 56, and the like. That is, the dry etching process in the MEMS is finished.

  Incidentally, the etching time shown in Table 3 is changed from the dry etching conditions shown in Table 2 to the dry etching conditions shown in Table 3, and the control unit detects the increase in etchant by the monitoring unit M. 60 is the time until the end of the dry etching process is determined.

  Thus, when the substrate S is subjected to the dry etching process to form the through portion penetrating in the thickness direction, the etching rate of the substrate for the dry etching process is reduced in the middle of the etching, and the energy of the etching plasma is reduced. Precisely, the operating pressure during dry etching is reduced, the high-frequency voltage applied to the high-frequency antenna 31 is reduced, the high-frequency voltage applied to the substrate electrode 24 is reduced, and the back surface of the substrate S is The pressure of helium gas as the cooling gas is reduced. That is, although the mechanical rigidity of the substrate S is reduced by increasing the depth of the penetration portion as the dry etching progresses, the temperature rise of the substrate S due to the etching plasma is suppressed along with the rigidity of the substrate S, The pressure of the helium gas on the back surface of the substrate S, that is, the stress applied to the substrate S is reduced. Therefore, it becomes possible to suppress the occurrence of cracks in the non-penetrating region between the penetrating part formed in the substrate S and the other penetrating part.

  Further, since the pressure of the helium gas is reduced and the energy of the etching plasma is reduced in this way, even if the cooling efficiency of the substrate by the helium gas is reduced, the influence of the heating of the substrate S, for example, the MEMS device manufacturing apparatus It is also possible to suppress etching variations caused by temperature variations among the plurality of substrates S processed in step 1 and burning of various patterning used in dry etching processing. Furthermore, although the etching rate of the substrate is reduced during the formation of the through portion in this way, since the etching is performed at a higher etching rate before that, the entire through portion is formed. Prolonged time required can be suppressed.

Moreover, in the present embodiment, the amount of helium gas supplied to the back surface of the substrate S is monitored by the pressure gauge 28b, and when an increase in the supply flow rate is detected, the dry etching rate is reduced. In addition, the pressure of the helium gas on the back surface of the substrate S is reduced. Therefore, it is possible to detect a decrease in rigidity of the substrate S and to reduce the pressure of the inert gas accordingly. Thus, by performing the dry etching process without decreasing the etching rate until immediately before the rigidity of the substrate S is reduced, it is possible to more reliably suppress the time required for forming the through portion from being prolonged. By performing the subsequent dry etching process in a state where the pressure applied to the substrate is smaller, it is possible to suppress the substrate from being cracked when the through portion is formed.
[Example]
Hereinafter, the manufacturing method of the MEMS device according to the present invention will be specifically described based on Examples and Comparative Examples.

  Using a substrate S having a diameter of 6 inches, a MEMS device in which the area of the through-holes opening on both front and back surfaces of the substrate S is 10 to 40% of the surface area and the back surface area of the substrate S, respectively. Manufactured.

  When forming the penetrating portion of the MEMS device, dry etching is performed under the conditions shown in Table 1 above, and the helium gas supply flow rate to the refrigerant space is rapidly increased by the pressure gauge 28b. Was detected, the conditions of the dry etching treatment were changed from the conditions shown in Table 1 to the conditions shown in Table 2 above. When dry etching treatment was performed under the conditions shown in Table 1, a steep increase in the helium gas was detected when the depth of the through portion reached 1.5 μm in the substrate S having a total thickness of 200 μm. It was. Further, since the time required for the depth of the penetrating portion to reach 1.5 μm is 8 minutes and 50 seconds as described in Table 1, the dry condition under the conditions described in Table 1 is used. The etching rate related to the etching process is 0.4 μm / min.

  Next, after 30 seconds passed under the conditions shown in Table 2, dry etching treatment was performed under the conditions shown in Table 3 above. Note that, when the dry etching process is completed under the conditions shown in Table 3, that is, when the formation of the through portion is completed, the monitoring unit M detects an increase in the amount of etchant contained in the etching plasma. When it was. The dry etching process under the conditions shown in Table 3 was performed for 4 minutes and 10 seconds. Under the conditions shown in Table 3, the portion of the through-hole forming region in the substrate S was etched by the thickness remaining without being etched by the dry etching process under the conditions in Table 1 above, that is, by 1.5 μm. The etching rate of the dry etching process performed under the conditions described in Table 3 is 0.35 μm / min.

In the MEMS device in which the penetration portion was formed in this way, no crack was generated in the non-penetration portion between the penetration portions.
[Comparative Example 1]
Using the same substrate S as in the above example, a MEMS device having the same ratio of the area of the through portion to the area of the front and back surfaces of the substrate S and the formation pattern of the through portion was manufactured. In this comparative example, when forming the penetrating portion of the MEMS device, dry etching treatment was performed under the conditions shown in Table 1 from the start of the formation to the completion of the formation. As described above, since the etching rate of the dry etching process performed under the conditions shown in Table 1 is 0.4 μm / min, it took 12 minutes and 00 seconds from the start of the formation of the through portion to its completion.

As described above, according to this comparative example, although the time required to form the penetrating portion is shorter than that in the above embodiment, the frequency of occurrence of cracks in the non-penetrating region existing between the penetrating portions formed in the substrate S is reduced. The cracks occurred in five of the five substrates S on which the penetrating portions were formed under the above conditions.
[Comparative Example 2]
Using the same substrate S as in the above example, a MEMS device having the same ratio of the area of the through portion to the area of the front and back surfaces of the substrate S and the formation pattern of the through portion was manufactured. In this comparative example, when forming the penetrating portion of the MEMS device, dry etching treatment was performed under the conditions described in Table 3 from the start of formation to the completion of formation. As described above, since the etching rate of the dry etching process performed under the conditions shown in Table 3 is 0.35 μm / min, it took 13 minutes and 30 seconds from the start of formation of the through portion to its completion.

  As described above, according to this comparative example, cracks do not occur in the non-penetrating regions existing between the penetrating portions formed in the substrate S as in the above-described embodiment. It took 25 times longer.

As described above, according to the MEMS device manufacturing method of the present embodiment, the effects listed below can be obtained.
(1) When a dry etching process is performed on the substrate S to form a penetrating portion penetrating in the thickness direction, the etching rate of the substrate S related to the dry etching process is determined along the etching plasma energy, that is, the dry plasma process. It is lowered by the working pressure during the etching process, the high-frequency voltage applied to the high-frequency antenna 31, and the high-frequency voltage applied to the substrate electrode 24, and the back surface of the substrate S, more precisely, the back surface of the substrate S and the substrate The pressure of helium gas in the refrigerant space formed by the recess 22a of the tray 22 on which S is placed is reduced. That is, although the mechanical rigidity of the substrate S is reduced due to the depth of the penetration portion being increased with the progress of the dry etching process, the temperature rise of the substrate due to the etching plasma is suppressed as the rigidity is reduced. Therefore, the pressure of the helium gas on the back surface of the substrate S, that is, the stress applied to the substrate S can be reduced, and as a result, a crack occurs in the non-penetrating region between the penetrating portion and the other penetrating portions. Can be suppressed. Further, since the pressure of the helium gas is reduced and the energy of the etching plasma is reduced in this way, even if the cooling efficiency of the substrate S by the helium gas is reduced, the influence of the heating of the substrate S, for example, It is also possible to suppress etching variations caused by temperature variations among a plurality of substrates processed in the MEMS device apparatus, and burning of various patterns used in dry etching processing. Furthermore, although the etching rate of the substrate S is reduced during the formation of the through portion in this way, the etching can be performed at a higher etching rate before that, and the entire through portion is formed. Prolonged time required can also be suppressed.

  (2) A period during which an increase in the supply flow rate of helium gas may occur due to other factors other than a decrease in the rigidity of the substrate S is set as a predetermined time, and the increase in the supply flow rate of helium gas detected after the predetermined time has elapsed The increase was caused by a decrease in the rigidity of the substrate S. This avoids erroneously detecting an increase in the supply amount of helium gas due to the above other factors as an increase in the supply amount of helium gas due to a decrease in the rigidity of the substrate S, that is, the end timing of the high-speed etching process.

  (3) The amount of helium gas supplied to the refrigerant space formed by the back surface of the substrate S, more precisely, the back surface of the substrate S and the recess 22a of the tray 22 on which the substrate S is placed is determined by the pressure gauge 28b. Monitored, after a predetermined period from the start of metering of helium gas, and when an increase in the helium gas supply flow rate is detected during the metering, the dry etching rate, in detail In addition, the operating pressure during the dry etching process, the high-frequency voltage applied to the high-frequency antenna 31, and the high-frequency voltage applied to the substrate electrode 24 are reduced, and in other words helium in the refrigerant space on the back surface of the substrate S. The gas pressure was reduced. Therefore, a decrease in the rigidity of the substrate S can be detected by increasing the helium gas supply flow rate, and the pressure of the helium gas can be decreased accordingly, without decreasing the etching rate until just before the rigidity of the substrate S is decreased. A dry etching process can be performed. Therefore, it is possible to more reliably suppress the time required for the formation of the through portion, and to carry out the subsequent dry etching process in a state where the pressure applied to the substrate S is smaller, thereby forming the through portion. Generation of cracks in the substrate S can be suppressed.

  (4) After reducing the energy of the etching plasma and reducing the pressure of the helium gas, the amount of the etching plasma by the monitoring unit M, in other words, the amount of the etchant contained in the gas phase of the MEMS device device When the increase in the amount was detected, the dry etching process for forming the through portion was terminated. As a result, it is possible to achieve a state in which the through-hole is reliably formed and the substrate S is hardly affected by the excessive dry etching process.

  (5) When the helium gas supply flow rate, in other words, the target value of the helium gas pressure in the refrigerant space is decreased as the helium gas supply flow rate increases, The differential pressure with respect to the side, that is, the surface of the tray 22 on the concave portion 22a side is set to “0”. Thereby, the force which pushes the board | substrate S to the etching surface side can be removed from this board | substrate S, and the crack which arises in the board | substrate S can be suppressed more reliably.

  (6) The substrate S to be processed is placed on the tray 22 and is placed on the substrate stage 21 together with this. As a result, a through-hole is formed in the substrate S, and even if the etching plasma and excitation gas flow into the back surface side of the substrate S, in other words, the tray side, the etching plasma and excitation gas pass through the tray 22. It reacts and is consumed on the tray 22. That is, it is possible to avoid corrosion of the substrate stage 21 due to etching plasma or excitation gas flowing from the through portion of the substrate S.

It should be noted that the above embodiment can be implemented with appropriate modifications as follows.
-Although octafluoropropane was used as etching gas, you may make it use the other gas which can etch the board | substrate S. FIG.

  As the substrate S, a substrate made of silicon as a forming material and having an insulating film of silicon dioxide embedded in advance as a through-hole forming region is used. However, the present invention is not limited thereto, and for example, a substrate in which the insulating film is silicon nitride or a substrate made of another forming material may be embedded as the through-hole forming region. Alternatively, a substrate made of silicon as a forming material or a substrate made of another material, in which the insulating film as the through-hole forming region is not provided, may be used.

Although the high frequency antenna 31 is wound twice around the outer periphery of the second cylindrical portion, it may have a shape wound around other times, for example, single, triple, or quadruple. .
-Although the said MEMS device manufacturing apparatus was equipped with the magnetic field coil 41, this magnetic field coil 41 does not need to be provided. In the MEMS device manufacturing apparatus, the high-frequency antenna 31 is wound around the outer peripheral surface of the second cylindrical portion.
The top surface 14 of the chamber body 10 may be provided on the surface on the plasma generation chamber 12a side so as to face the substrate electrode 24 provided in the substrate stage 21, and the shape of the high-frequency antenna 31 is a coil shape. The structure may be changed from flat to flat.

  Although the concave portions 21a and 22a are provided on the tray mounting surface of the substrate stage 21 and the substrate mounting surface of the tray 22, respectively, the concave portions 21a and 22a may not be provided. However, as described above, by providing these recesses 21a and 22a, the cooling efficiency of the substrate by helium gas is improved.

  The frequency of the high frequency voltage applied to the high frequency antenna 31, that is, the frequency of the high frequency voltage defined by the high frequency power supply 32 for the high frequency antenna was set to 13.75 MHz. Not limited to this, the frequency may be another frequency.

Although helium gas is used as the cooling gas supplied to the refrigerant space, other inert gas such as argon gas or nitrogen gas may be used.
Instead of placing the tray 22 on the substrate stage 21, the substrate S may be placed directly on the substrate stage 21, and a dry etching process may be performed thereon. However, as described above, it is possible to avoid the corrosion of the substrate stage 21 by placing the tray 22 on the substrate stage 21.

  In addition, when the tray 22 is not placed on the substrate stage 21, an electrostatic chuck can be used as means for holding the placement position of the substrate S instead of the mechanical chuck 23.

-While the dry etching process is being performed under the conditions shown in Table 1, the flow rate of the helium gas supplied to the refrigerant space is monitored, and when the increase is detected, the conditions for the dry etching process are determined. The conditions in Table 1 were changed to those in Table 2. However, the time required for the substrate S to bend from the start of dry etching is measured in advance by experiments or the like, and the etching conditions are measured before this time elapses from the start of dry etching. May be changed. This
(7) If the rate of dry etching is reduced and the pressure of helium gas is reduced before the amount of helium gas supplied to the back surface of the substrate S increases, the rigidity decreases due to the progress of dry etching. Before the substrate S bends to the etching surface side due to the above, the force for pushing the substrate S to the etching surface side can be reduced. That is, it is possible to suppress the force applied to the substrate S due to the deformation caused by such bending, and consequently to suppress the generation of cracks in the substrate S.

Such effects can be obtained.
When changing the dry etching conditions, a process based on the conditions shown in Table 2 above, that is, etching gas is introduced but the antenna power and the bias power are both “0” and the substrate S is not etched. A process was set up. However, the present invention is not limited to this, and the conditions shown in Table 2 may be changed directly from the conditions shown in Table 1 to the conditions shown in Table 3. However, by providing the processing steps shown in Table 2, the condition of Table 3 is directly changed from the conditions of Table 1 by restarting dry etching after exhausting the helium gas when the rigidity reduction of the substrate S is detected. In other words, the possibility of cracking in the substrate S can be reduced as compared with the case where the helium gas is exhausted and the dry etching conditions are changed simultaneously.

The pressure of the helium gas under the conditions shown in Table 2 and Table 3 is not limited to “0”, and the pressure is lower than the condition before the rigidity reduction of the substrate S is detected, that is, the condition shown in Table 1. That's fine. In short, it may be set according to the rigidity of the substrate S on which the penetrating portion is being formed, and set to a value that does not cause cracks in the substrate S.

  The end time of the dry etching process is when the monitoring unit M monitors the content of the etchant in the gas phase in the plasma generation chamber 12a or the amount of the product by dry etching, and detects this increase. I did it. Not limited to this, the etching time according to the dry etching conditions in Table 3 is calculated from the thickness of the substrate S that is not etched at the start of the dry etching process under the conditions and the etching rate of the substrate S per unit time according to the conditions. You may make it calculate.

  For example, the etching rate at which the substrate S is etched is associated with the energy of the etching plasma, in other words, the etching rate corresponding to the dry etching conditions shown in Table 1 above, and the dry etching conditions shown in Table 3 above. The etching rate corresponding to is stored in advance in the storage unit 60a of the control unit 60. Next, when the controller 60 detects an increase in the supply flow rate of helium gas by the pressure gauge 28b, the etching plasma energy used before the detection, that is, the etching corresponding to the conditions described in Table 1 is used. The speed and the energy of the etching plasma used after the detection, that is, the etching speed corresponding to the conditions shown in Table 3 are extracted from the storage unit 60a. Thereafter, the etching amount Aa before the increase detection of the helium gas supply flow rate is calculated based on the etching rate corresponding to the conditions described in Table 1 and the processing time performed at this etching rate.

Here, the etching performed after the detection of the sudden increase in the helium gas supply flow rate, which is a numerical value defined by the thickness of the substrate S, that is, the dry etching processing time according to the conditions described in Table 3 is t, When Ap is the total etching amount required to form the portion, and v is the etching rate after detecting the increase in the helium gas supply flow rate, that is, the etching rate corresponding to the conditions described in Table 3. t = (Ap−Aa) / v
The processing time is determined based on the above.

This
(8) When detecting an increase in the helium gas supply flow rate, a value obtained by subtracting the etching amount before the detection from the total etching amount, that is, the thickness of the remaining film in the region to be the through portion, is calculated, and the remaining dry If the etching time is set, without continuing to monitor the progress of dry etching until the formation of the penetrating portion is completed, that is, without continuously monitoring the etchant or the like in the etching plasma by the monitoring portion M, The through portion can be formed while suppressing an excessive etching process on the substrate S only by a simple process of setting an etching time at the start of the dry etching process under the conditions described in Table 3.

Such effects can be obtained.
The increase in the supply flow rate of helium gas detected after a predetermined time has elapsed, that is, after the time from the start of the dry etching process shown in FIG. It was detected as an increase in the supply flow rate due to the decrease. Not limited to this, for example, immediately after the dry etching process for the substrate S is started from the thermal expansion coefficient of the substrate S and the energy of the etching plasma supplied to the substrate S, that is, immediately after the cooling of the substrate S is started. Even if it exists, when it is thought that expansion of the said refrigerant | coolant space and the sealing performance of this space do not produce easily, it is not necessary to provide the said predetermined time.

DESCRIPTION OF SYMBOLS 10 ... Chamber main body, 11 ... 1st cylindrical part, 11a ... Substrate stage chamber, 12 ... 2nd cylindrical part, 12a ... Plasma generating chamber, 13 ... Bottom plate, 13a ... Insulating member, 14 ... Top plate, 15 ... Exhaust pipe, DESCRIPTION OF SYMBOLS 16 ... Vacuum exhaust part, 21 ... Substrate stage, 21a ... Recess, 21b ... Helium gas flow path, 22 ... Tray, 22a ... Recess, 22b ... Helium gas flow path, 23 ... Mechanical chuck, 24 ... Substrate electrode, 25 ... Substrate High frequency power supply for electrodes, 26 ... capacitor, 27 ... vacuum pump, 28a ... flow metering unit, 28b ... pressure gauge, 28c ... helium gas control unit, 31 ... high frequency antenna, 32 ... high frequency power supply for high frequency antenna, 41 ... magnetic field coil , 41T ... upper coil, 41M ... middle coil, 41B ... lower coil, 51 ... gas introduction part, 52 ... gas supply part, 53, 55 ... valve, 54 ... flow metering , 56 ... gas flow channel, 60 ... control unit, 60a ... storage unit, M ... monitoring unit.

Claims (11)

A method for manufacturing a MEMS device, wherein a penetrating portion penetrating between a front surface and a back surface of a substrate is formed by etching plasma irradiated on the surface of the substrate,
When forming the penetration part,
After cooling the substrate that is heated in accordance with the energy of the etching plasma with an inert gas as a cooling medium pumped to the back surface of the substrate, the pressure of the inert gas on the back surface of the substrate is A method for manufacturing a MEMS device, wherein the energy is lowered together with energy of etching plasma. In the manufacturing method of the MEMS device of Claim 1,
The pressure of the inert gas in the refrigerant space is a target while the inert gas is pumped to the refrigerant space surrounded by the concave portion provided on the placement surface of the stage on which the substrate is placed and the back surface of the substrate. The supply flow rate of the inert gas to be a value,
When forming the penetration part,
Lowering the target value together with the energy of the etching plasma when the supply flow rate of the inert gas increases during metering after a predetermined time has elapsed from the start of metering of the inert gas with respect to the target value. A manufacturing method of a MEMS device characterized by the above. In the manufacturing method of the MEMS device of Claim 2,
Monitoring the supply flow rate of the inert gas to the refrigerant space;
The target value together with the energy of the etching plasma when an increase in the supply flow rate of the inert gas is detected during metering after a predetermined time has elapsed from the start of metering of the inert gas with respect to the target value. The manufacturing method of the MEMS device characterized by the above-mentioned. In the manufacturing method of the MEMS device of any one of Claims 1-3,
Monitoring the amount of etchant contained in the etching plasma;
The method of manufacturing a MEMS device, wherein the supply of the etching plasma is terminated when an increase in the amount of the etchant is detected after lowering the pressure of the inert gas together with the energy of the etching plasma. In the manufacturing method of the MEMS device of any one of Claims 1-4,
A pressure difference between the front surface side and the back surface side of the substrate is set to “0” when both the pressure of the inert gas and the energy of the etching plasma on the back surface of the substrate are lowered. Production method. A MEMS device manufacturing apparatus in which a penetrating portion penetrating between a front surface and a back surface of a substrate is formed by etching plasma irradiated on the surface of the substrate,
An etching plasma irradiation section for irradiating the surface of the substrate with etching plasma;
A substrate cooling section that pumps an inert gas as a cooling medium to the back surface of the substrate;
After cooling the substrate that is heated in accordance with the energy of the etching plasma with an inert gas as a cooling medium pumped to the back surface of the substrate, the pressure of the inert gas on the back surface of the substrate is An apparatus for manufacturing a MEMS device, comprising: a control unit that controls the etching plasma irradiation unit and the substrate cooling unit in a manner of lowering together with energy of etching plasma. The MEMS device manufacturing apparatus according to claim 6,
The substrate cooling unit is
The pressure of the inert gas in the refrigerant space is a target while the inert gas is pumped to the refrigerant space surrounded by the recess provided on the mounting surface of the stage on which the substrate is mounted and the back surface of the substrate. A metering unit for metering the supply flow rate of the inert gas so as to be a value,
The controller is
Lowering the target value together with the energy of the etching plasma when the supply flow rate of the inert gas increases during metering after a predetermined time has elapsed from the start of metering of the inert gas with respect to the target value. An MEMS device manufacturing apparatus characterized by the above. The MEMS device manufacturing apparatus according to claim 7,
An inert gas supply flow rate monitoring unit for monitoring the supply flow rate of the inert gas to the refrigerant space;
The controller is
When an increase in the inert gas supply flow rate is detected by the inert gas supply flow rate monitoring unit during metering after a predetermined time has elapsed since the start of metering the inert gas with respect to the target value, The target value is lowered together with the energy of the etching plasma. A MEMS device manufacturing apparatus, wherein: The MEMS device manufacturing apparatus according to claim 8,
A storage unit for storing an etching rate at which the substrate is etched in association with energy of the etching plasma;
The controller is
When an increase in the supply flow rate of the inert gas is detected by the inert gas supply flow rate monitoring unit, an etching rate corresponding to the energy of the etching plasma used before the detection is used, and used after the detection. An etching rate corresponding to the energy of the etching plasma is extracted from the storage unit;
Etching time after the detection is t, and the total etching amount required to form the through-hole in the substrate is Ap, and the etching rate and the etching rate before the detection were performed. When the etching amount before the detection calculated by the control unit based on the processing time is Aa,
The processing time is determined based on t = (Ap−Aa) / v. A MEMS device manufacturing apparatus, wherein:
(Here, Ap is the total etching amount required to form the through portion, and Aa is calculated by the control unit based on the etching rate before detection and the processing time performed at the etching rate. The etching amount before the detection to be performed, and v is the etching rate after the detection.) In the manufacturing apparatus of the MEMS device of any one of Claims 6-9,
An etchant amount monitoring unit for monitoring the amount of etchant contained in the etching plasma;
The controller is
A dry etching process is ended when an increase in the amount of the etchant is detected by the etchant amount monitoring unit after lowering the pressure of the inert gas together with the energy of the etching plasma. . In the manufacturing apparatus of the MEMS device of any one of Claims 6-10,
The substrate cooling unit is
A first stage for placing the substrate;
A second stage for placing the first stage;
The first stage is a plurality of stages associated with each of a plurality of substrates,
The second stage is one stage that is common to a plurality of first stages. An MEMS device manufacturing apparatus, wherein:

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