JP4956717B2 - Plasma processing method, etching method, plasma processing apparatus and etching apparatus - Google Patents

Description

  The present invention relates to a plasma processing method.

  Conventionally, an etching method has been proposed in which an object to be processed, for example, a semiconductor wafer (hereinafter referred to as “wafer”) is etched by high-density plasma to form ultrafine contact holes. However, if a contact hole with a high aspect ratio is formed by such an etching method, charging damage due to electron shading occurs and a desired contact hole cannot be formed.

Here, the electronic shading phenomenon and the accompanying charging damage will be described with reference to FIG. Incidentally, FIG. 9, SiO ₂ (silicon oxide) film layer 12 and a photoresist film layer 14 is laminated on the semiconductor substrate 10, a SiO ₂ film layer 12 based on the photo-resist film layer 14 to form the pattern 16 2 is a schematic cross-sectional view showing a wafer W in the middle of forming a contact hole 18. FIG.

As shown in the figure, electrons (e ⁻ ) collide with the sidewalls of the pattern 16 as the etching of the contact hole 18 progresses and the aspect ratio becomes higher, whereas positive ions (I ⁺ ) Since the light is incident substantially perpendicular to the bottom, the side wall of the pattern 16 and the upper inner wall of the contact hole 18 are charged up (charged) to a negative charge. This negative charge forms an electric field that acts as a barrier for electrons. Accordingly, electrons having only a small velocity component in the vertical direction with respect to the bottom of the contact hole 18 are decelerated by the electric field and rebounded so that they cannot enter the pattern 16. This is the electronic shading phenomenon.

  When the above-described electron shading occurs, more positive ions are incident on the bottom of the contact hole 18 than the electrons as described above, so that the lower wall (side wall) of the contact hole 18 is charged to a positive charge. As a result, for example, the incident direction of ions serving as etching species is bent in the direction of the side surface of the contact hole 18 due to the charge-up, thereby causing problems such as a shape abnormality such as a notch. This is charging damage.

  Therefore, by intermittently applying high-frequency power for generating plasma, the electron temperature of the plasma is lowered to control radicals to a predetermined state, and when the ion sheath disappears when the high-frequency power is turned off, the wafer W By charging negative ions and electrons into the lower portion of the contact hole 18 by a continuous wave bias power applied to the positive charge, charging of positive charges is eliminated and charging damage is prevented. The electron temperature is a measure representing the average thermal kinetic energy of electrons in plasma, and the sheath refers to a space charge layer formed around the wafer W in the presence of plasma.

  However, for example, when an ultrafine contact hole having an inner diameter of about 0.18 μm or less is formed, charging damage cannot be prevented even by the etching method described above. In other words, as the aspect ratio of the contact hole increases, the electron shading effect becomes more prominent and the amount of positive charge on the lower wall of the contact hole increases, so depending on the negative ions generated by dissociation of the processing gas, The positive charge cannot be electrically neutralized. In addition, since the electrons are isotropically incident, they reach the lower part of the contact hole, but the charging of the positive charge is not solved.

  The present invention has been made in view of the above-mentioned problems of the prior art, and the object of the present invention is to prevent charging damage even if a high aspect ratio contact hole is formed by plasma. It is an object of the present invention to provide a new and improved plasma processing method capable of forming a desired contact hole.

  In order to solve the above-described problem, according to a first aspect of the present invention, a processing gas containing at least fluorocarbon is introduced into a processing chamber, and high-frequency waves are respectively applied to a first electrode and a second electrode that are opposed to each other in the processing chamber. A high frequency power applied to a second electrode in a plasma processing method in which power is applied to turn a processing gas into plasma and plasma treatment is performed on a silicon oxide film layer formed on a target object placed on the second electrode The frequency is lower than the frequency of the high-frequency power applied to the first electrode, the high-frequency power is intermittently applied to the first electrode, and oxygen is intermittently added to the processing gas. A plasma processing method is provided.

According to such a configuration, when the high frequency power applied intermittently to the first electrode is on, the processing gas is dissociated to generate negative ions of electrons and oxygen, and these electrons and negative ions are turned off when the high frequency power is off, and When the high-frequency power applied to the second electrode is in a positive cycle, it can be drawn into the lower part of the contact hole formed in the SiO ₂ film layer. As a result, positive charges generated on the lower wall portion of the contact hole by electrons and negative ions are electrically neutralized, so that charging of positive charges can be eliminated and charging damage can be prevented. In the present specification, the positive cycle means the first cycle higher than the potential of the portion where electrons and negative ions exist in the processing chamber (processing vessel) in all cycles of the high-frequency power applied to the second electrode. This refers to a cycle in which the potential of the two electrodes is higher. The aspect ratio refers to the ratio (b / a) between the inner diameter (width) a and the depth (height) b of the pattern formed in the contact hole or the photoresist film layer.

In addition, it is known that when O ₂ is added to the processing gas, the photoresist film layer and its pattern shoulder are scraped and damaged, but in the present invention, O ₂ is intermittently added to the processing gas. The damage is unlikely to occur and a contact hole can be formed based on a predetermined pattern. Further, since the processing gas contains a fluorocarbon (CF) gas, the protective film is applied to the photoresist film layer and the pattern shoulder when the high frequency power applied intermittently to the first electrode is turned off while performing the predetermined etching. This can further reduce the damage caused by the addition of O ₂ .

Further, if oxygen is periodically added to the processing gas, the generation of negative ions of the oxygen and the formation of the protective film can be more reliably performed, and addition control of O ₂ can be easily performed. .

In addition, when a contact hole is formed in the silicon oxide film, the amount of oxygen added may be increased according to the increase in the aspect ratio of the contact hole. The above-mentioned charging damage is likely to occur as the aspect ratio increases as the etching progresses. Therefore, if the amount of O ₂ added is increased in accordance with the increase in the aspect ratio, the charging damage will occur even if the etching progresses. Damage can be reliably prevented. Further, since the amount of O ₂ added is small at the initial stage of processing, damage to the photoresist film layer and the pattern shoulder can be reduced.

According to the second aspect of the present invention, a processing gas containing at least fluorocarbon and oxygen is continuously introduced into the processing chamber during the etching process, and the first electrode and the second electrode arranged to face each other in the processing chamber. In the plasma processing method of applying plasma processing to the silicon oxide film layer formed on the object to be processed placed on the second electrode by applying high-frequency power to each of the plasma processing gas, The frequency of the high frequency power to be applied is lower than the frequency of the high frequency power applied to the first electrode. While the high frequency power is intermittently applied to the first electrode and the amount of oxygen added to the process gas is increased or decreased, There is provided a plasma processing method characterized by performing plasma processing.

According to this configuration, since O ₂ is added to the processing gas, charging damage accompanying an increase in the aspect ratio can be prevented as in the first aspect of the invention. Further, when the amount of O ₂ added is increased, the amount of oxygen negative ions generated can be increased, and when the amount of O ₂ added is decreased, a photoresist film layer and a pattern shoulder are formed by a protective film based on a CF-based gas. Therefore, it is possible to perform predetermined patterning while eliminating charging damage.

  According to the third aspect of the present invention, a processing gas containing at least fluorocarbon and oxygen is introduced into the processing chamber, and high frequency power is applied to each of the first electrode and the second electrode arranged to face each other in the processing chamber. Then, in the plasma processing method of converting the processing gas into plasma and performing plasma processing on the silicon oxide film layer formed on the target object placed on the second electrode, the frequency of the high frequency power applied to the second electrode is The plasma processing is performed while the frequency of the high frequency power applied to the first electrode is lower than that of the first electrode, and the high frequency power is intermittently applied to the first electrode to increase the amount of oxygen added to the processing gas. A plasma processing method is provided.

According to such a configuration, since the treatment is performed while increasing the amount of O ₂ added, the amount of O ₂ added is small at the initial stage of the treatment, and the total amount of O ₂ introduced (input amount) is the same as that in the case of continuous introduction. Since it can be suppressed to less than the amount introduced, the photoresist film and its shoulder are less likely to be damaged. In addition, the amount of O ₂ added is increased with the treatment, and the amount of O ₂ added in the initial stage of the treatment can be added thereafter, so that charging damage can be reliably prevented.

  In addition, when forming holes in the silicon oxide film layer, if the amount of oxygen added is increased in accordance with the increase in the aspect ratio of the holes, more negative oxygen ions are generated as the aspect ratio increases. Can prevent charging damage more reliably.

  According to the present invention, since negative oxygen ions can be introduced into the bottom of the contact hole, even when a high aspect ratio contact hole is formed by high-density plasma, positive charge charging on the lower wall of the contact hole is possible. Can be prevented, and a desired contact hole can be formed.

  Hereinafter, preferred embodiments in which a plasma processing method according to the present invention is applied to a plasma etching method will be described with reference to the accompanying drawings.

(First embodiment)
(1) Configuration of Etching Apparatus First, the configuration of the etching apparatus 100 will be described with reference to FIG. The processing chamber 102 of the etching apparatus 100 is formed in a conductive and airtight processing container 104. In the processing chamber 102, a conductive second electrode 106 that also serves as a mounting table for the wafer W and a conductive first electrode 108 are arranged to face each other, and between the first electrode 108 and the processing container 104. Insulating member 110 is interposed. The first electrode 108 is connected to a high-frequency power source 114 that outputs high-frequency power of, for example, 27 MHz for plasma generation via a matching unit 112. The second electrode 106 has a high frequency power for bias having a frequency that is lower than the frequency of the high frequency power applied to the first electrode 108 via the matching unit 116 and does not generate plasma, for example, 800 kHz. Is connected to a high-frequency power source 118.

  The first electrode 108 is formed with a number of gas discharge holes 108a, and the first and second gas supply pipes 120 and 140 are connected to the gas discharge holes 108a via the gas diffusion chamber 108b. ing. The first gas supply pipe 120 is connected to first to third gas supply sources 134, 136 via open / close valves 122, 124, 126 and first to third flow rate adjusting valves (mass flow controllers) 128, 130, 132. , 138 are connected. In addition, a fourth gas supply source 146 is connected to the second gas supply pipe 140 via an open / close valve 142 and a fourth flow rate adjustment valve 144. Further, a controller 148 for controlling the gas flow rate is connected to the first to fourth flow rate adjustment valves 128, 130, 132, and 144. An exhaust pipe 150 communicating with a vacuum pump (not shown) is connected below the processing chamber 102.

(2) Etching Step Next, the etching step according to the present embodiment will be described with reference to FIGS. First, the wafer W described above is placed on the second electrode 106 set at 20 ° C., for example. At this time, the temperature of the inner wall surface of the processing chamber 102 and the first electrode 108 is set to 60 ° C., for example. Subsequently, the controller 148 appropriately adjusts the first to third flow rate adjusting valves 128, 130, and 132, and processing gases such as C ₄ F ₈ , CO, and Ar are supplied from the first to third gas supply sources 134, 136, and 138. Are introduced into the processing chamber 102 at flow rates of 11 sccm, 50 sccm, and 200 sccm, respectively. Further, the inside of the processing chamber 102 is evacuated, and the pressure in the processing chamber 102 is set to 45 mTorr, for example. At this time, the fourth flow rate adjusting valve 144 is closed and the supply of O ₂ is stopped.

Then, for example, a high frequency power of 27 MHz (hereinafter referred to as “pulse power”) that repeatedly turns on and off at a predetermined cycle is applied to the first electrode 108, and a continuous wave of, for example, 800 kHz is applied to the second electrode 106. High frequency power (hereinafter referred to as “bias power”) is applied. As a result, electrons, ions, and radicals in the plasma generated by dissociation of the processing gas are drawn into the wafer W, and a contact hole 18 is formed in the SiO ₂ film layer 12 of the wafer W.

The plasma generation state is monitored by, for example, a sensor that detects the emission spectrum of the plasma, and information from this sensor is transmitted to the controller 148. When the controller 148 determines that the plasma is stabilized and the SiO ₂ film layer 12 is subjected to a stable etching process, the controller 148 applies a predetermined pulse voltage to the fourth flow rate adjusting valve 144. The fourth flow rate adjusting valve 144 opens the valve when the pulse voltage is on, supplies O ₂ from the fourth gas supply source 146 into the gas diffusion chamber 108b, and turns the valve on when the pulse voltage is off. Close and stop supplying O ₂ . As a result, O ₂ is added to the processing gas in the gas diffusion chamber 108b in synchronization with the on / off of the pulse voltage, and the processing gas is supplied into the processing chamber 102 through the gas discharge hole 108a.

Further, as shown in FIG. 2, the addition amount (flow rate) at the time of adding O ₂ is increased in accordance with the increase of the processing time, that is, the aspect ratio of the contact hole 18 due to the progress of etching. The change in the aspect ratio is determined from the etching time based on the above relationship in the controller 148 by previously obtaining a correspondence relationship between the etching time and the increase in the aspect ratio. With such a configuration, since the addition amount of O ₂ is small at the initial stage of processing with a small aspect ratio, the shoulder portions of the photoresist film layer 14 and the pattern 16 are difficult to be cut, and the SiO ₂ film layer 12 based on the predetermined pattern 16. Can be etched. In addition, the total introduction amount of O ₂ (input amount), so can be below the total introduction amount in the case of continuous introduction of O _2, it can be reliably prevented scraping the shoulder portion of the photoresist layer 14. Also, since the amount of O ₂ added increases as the aspect ratio increases, charging damage can be reliably eliminated.

Further, 1 addition time of O ₂ per cycle, several m seconds to several 10m seconds, is set to, for example, 5m sec ~10m seconds, additive-free time of the O ₂ is set longer than the addition time of the O ₂ ing. Therefore, since the addition time of O ₂ is very short compared with the non-addition time, even if O ₂ is constantly added, an amount of O ₂ that damages the photoresist film layer 14 or the like may be added to the processing gas. The shoulders of the photoresist film layer 14 and the pattern 16 are not substantially damaged.

(3) Reason for eliminating charging damage Next, the reason for eliminating charging damage caused by the addition of O ₂ will be described with reference to FIGS. 3 and 4. FIG. As shown in FIG. 3, pulse power and bias power are applied to the first electrode 108 and the second electrode 106 during processing, respectively. O ₂ added to the processing gas is dissociated with C ₄ F _{8 and the} like when the pulse power is turned on, and positive ions, negative ions, radicals, and electrons are generated. Among these, the negative ions or electrons of oxygen that eliminate the positive charges charged up under the contact hole 18 are when the pulse power is off and the bias power is in a positive cycle (shaded area in FIG. 3). It is drawn into the contact hole 18.

That is, oxygen negative ions cannot pass through the sheath formed between the wafer W and the plasma when the pulse power is on, even if the bias power is in a positive cycle. Can't reach. On the other hand, when the pulse power is off, the sheath disappears as shown in FIG. 4, and therefore, when the bias power is in a positive cycle, negative oxygen ions (I ⁻ ) and electrons are in the contact hole 18. To reach the bottom.

As a result, the positive charges charged on the lower wall portion of the contact hole 18 are electrically neutralized by the negative ions and electrons of oxygen, and the charging is eliminated. As a result, even in the contact hole 18 having an increased aspect ratio, positive ions (etching species) dissociated from C ₄ F ₈ are incident on the bottom surface of the contact hole 18 in a direction perpendicular to the contact hole 18 having a predetermined shape. Is formed.

Since the present embodiment is configured as described above, the addition and non-addition of O ₂ added to the processing gas are switched at a predetermined cycle, and the addition amount at the time of O ₂ addition is increased according to the aspect ratio. The charging of the lower wall portion of the contact hole 18 can be eliminated while maintaining the pattern 16 in the initial state, and the contact hole 18 having a desired high aspect ratio can be formed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. Note that this embodiment, the point of adding the amount of O ₂ to O ₂ while relatively decreasing the process gas, different from the first embodiment.

That is, in the present embodiment, before the start of processing, for example, the processing gas to which O ₂ having a flow rate of 5 sccm is added is supplied into the processing chamber 102, and after the predetermined processing conditions are satisfied, the first electrode 108 and the first electrode The above-described power is applied to the two electrodes 106, and the wafer W is etched. After confirming that the plasma has stabilized, the controller 148 adjusts the opening of the fourth flow rate adjusting valve 144 according to the processing elapsed time, that is, the increase in the aspect ratio of the contact hole 18, and the inside of the gas diffusion chamber 108 b. The flow rate of O ₂ introduced into is periodically increased or decreased. As a result, as shown in FIG. 5, the amount of O ₂ added increases stepwise as the aspect ratio increases. In the present embodiment, the time for supplying O ₂ at a high flow rate into the gas diffusion chamber 108b is set to several milliseconds to several tens milliseconds, for example, 5 milliseconds to 10 milliseconds. On the other hand, the time for supplying O ₂ at a low flow rate into the gas diffusion chamber 108b is set longer than the time for supplying O ₂ at a high flow rate. Other configurations are the same as those in the first embodiment described above.

The present embodiment is configured as described above, and O ₂ is constantly added to the processing gas during processing. Therefore, more negative ions of oxygen can be generated, and charging can be more effectively generated. It can be surely prevented. In addition, the amount of O ₂ added is increased or decreased and is increased as the aspect ratio is increased, so that damage to the photoresist film layer 14 and the shoulder of the pattern 16 due to the addition of O ₂ can be minimized.

(Third embodiment)
Next, a third embodiment of the present invention will be described. Note that this embodiment in that while continuously increasing the amount of O ₂ addition of O ₂ in the processing gas is different from the first and second embodiments.

That is, in this embodiment, first, a processing gas not added with O ₂ is introduced into the processing chamber 102, plasma is generated after the above-described conditions are satisfied, and the wafer W is etched. Next, when the controller 148 confirms that the plasma is stable, the controller 148 increases the voltage applied to the fourth flow rate adjustment valve 144 according to the increase in the aspect ratio of the contact hole 18. As a result, as shown in FIG. 6, the amount of O ₂ added to the processing gas is continuously increased as the aspect ratio increases. Other configurations are the same as those in the first embodiment described above.

The present embodiment is configured as described above, and the amount of O ₂ added is continuously increased in accordance with the increase in the aspect ratio, so that charging damage can be more reliably eliminated and the processing gas can be reduced. Since the total input amount of O ₂ does not exceed the amount necessary for preventing the occurrence of charging damage, the shoulder of the photoresist film layer 14 can be more reliably prevented.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, this invention is not limited to this structure. Within the scope of the technical idea described in the claims, those skilled in the art will be able to conceive of various changes and modifications, and these changes and modifications are also within the technical scope of the present invention. It is understood that it belongs to.

  For example, in the above-described embodiment, the configuration in which the increase in the aspect ratio of the contact hole is determined from the etching time has been described as an example, but the present invention is not limited to such a configuration. For example, the present invention can be implemented even if a configuration in which the relationship between the plasma component change in the processing chamber and the increase in the aspect ratio is obtained in advance and the increase in the aspect ratio is determined from the measured plasma component change during the processing is employed. can do.

Further, in the above embodiment, a configuration in which a constant amount of O ₂ is intermittently or increased or decreased in accordance with an increase in aspect ratio has been described as an example. The present invention is not limited to such a configuration. For example, when the amount of O ₂ added to the processing gas is increased in accordance with the increase in the aspect ratio, it is increased or decreased in a curve as shown in FIG. 7, or stepwise (multi-stage) as shown in FIG. However, the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the addition of O ₂ after stabilization of the plasma, or to select other additive-free, although the configuration to increase or decrease the amount of O ₂ is described as an example, the present invention is to such a structure is not limited, for example, the addition of just before the charging damage occurs above O _2, or to select other additive-free, even if increase or decrease or increase the amount of O ₂ can be used to practice the present invention.

In the above-described embodiment, the configuration in which O ₂ is added to the mixed gas of C ₄ F ₈ and CO and Ar as the processing gas has been described as an example. However, the present invention is not limited to such a configuration, If the processing gas contains at least a fluorocarbon, the present invention can be implemented even if O ₂ is added to other processing gases.

Furthermore, in the above-described embodiment, the configuration in which O ₂ is added to the processing gas in the gas diffusion chamber has been described as an example. However, the present invention is not limited to this configuration, and O ₂ is directly contained in the processing chamber. Even if it supplies, this invention can be implemented.

In the above embodiment, the flow rate (addition amount) of O ₂ has been described by taking as an example a configuration in which the flow rate adjustment valve that adjusts the opening degree with voltage is used. However, the present invention is limited to this configuration. If the flow rate of O ₂ can be adjusted, the present invention can be implemented using other supply amount adjusting means.

Furthermore, in the above-described embodiment, the configuration in which the state of plasma is detected by an optical sensor has been described as an example. However, the present invention is not limited to such a configuration, and for example, a time for plasma stabilization is obtained in advance. In the actual processing, the present invention can be implemented even if the O ₂ supply amount is controlled based on the time.

  In the above-described embodiment, the configuration in which high-frequency power is intermittently applied to the first electrode and continuous-wave high-frequency power is applied to the second electrode has been described as an example. However, the present invention is limited to this configuration. However, for example, the present invention can also be implemented by applying both the high-frequency powers to the second electrode on which the object to be processed is placed. The present invention can also be applied to a plasma processing apparatus in which a magnetic field is formed in the processing chamber.

It is a schematic sectional drawing which shows the etching apparatus which can apply this invention. It is a schematic explanatory view for explaining a supply structure of O ₂ to be applied to the etching apparatus shown in FIG. It is a schematic sectional drawing for demonstrating the cancellation reason of charging damage. It is a schematic sectional drawing for demonstrating the cancellation reason of charging damage. It is a schematic explanatory view for explaining the supply structure of the other O _2. It is a schematic explanatory view for explaining the supply structure of the other O _2. It is a schematic explanatory view for explaining the supply structure of the other O _2. It is a schematic explanatory view for explaining the supply structure of the other O _2. FIG. 10 is a schematic explanatory diagram for explaining charging damage due to electronic shading generated by a conventional etching method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Etching apparatus 102 Processing chamber 106 2nd electrode 108 1st electrode 114,118 High frequency power supply 128 1st flow regulating valve 130 2nd flow regulating valve 132 3rd flow regulating valve 134 1st gas supply source 136 2nd gas supply source 138 Third gas supply source 144 Fourth flow rate adjustment valve 146 Fourth gas supply source 148 Controller W Wafer

Claims (13)

A processing gas containing at least fluorocarbon is introduced into the processing chamber, and two high-frequency powers are applied to the second electrode on which the object to be processed is placed, out of the first electrode and the second electrode arranged opposite to each other in the processing chamber. In the plasma processing method of converting the processing gas into plasma and performing plasma processing on the silicon oxide film layer formed on the target object placed on the second electrode:
One high frequency power applied to the second electrode is pulsed power;
The other high-frequency power applied to the second electrode is lower than the frequency of the one high-frequency power;
Oxygen is intermittently added to the processing gas,
The plasma treatment method is characterized in that the oxygen non-addition time is longer than the oxygen addition time.   The plasma processing method according to claim 1, wherein the oxygen is periodically added to the processing gas. A processing gas containing at least fluorocarbon is introduced into the processing chamber, and two high-frequency powers are applied to the second electrode on which the object to be processed is placed, out of the first electrode and the second electrode arranged opposite to each other in the processing chamber. In an etching method in which the processing gas is turned into plasma and an etching process is performed on a silicon oxide film layer formed on an object to be processed placed on the second electrode:
One high frequency power applied to the second electrode is pulsed power;
The other high-frequency power applied to the second electrode is lower than the frequency of the one high-frequency power;
Oxygen is intermittently added to the processing gas,
The etching method characterized in that the oxygen non-addition time is longer than the oxygen addition time.   The etching method according to claim 3, wherein the oxygen is periodically added to the processing gas.   The contact hole is formed in the silicon oxide film layer, and the addition amount of the oxygen is increased according to an increase in an aspect ratio of the contact hole. The etching method as described. A processing gas containing at least fluorocarbon and oxygen is continuously introduced into the processing chamber during the etching process, and a second electrode on which the object to be processed is placed among the first electrode and the second electrode arranged to face each other in the processing chamber. In an etching method in which two high-frequency powers are applied to an electrode to turn the processing gas into plasma, and an etching process is performed on a silicon oxide film layer formed on an object to be processed placed on the second electrode:
One high frequency power applied to the second electrode is pulsed power;
The other high-frequency power applied to the second electrode is lower than the frequency of the one high-frequency power;
In addition to the addition of oxygen to the processing gas, the amount of oxygen added is relatively increased or decreased during the etching process according to the increase in the aspect ratio of the holes formed in the silicon oxide film layer during the etching process. Let
An etching method, wherein the peak of the oxygen addition amount is increased stepwise while repeating the increase and decrease of the oxygen addition amount stepwise. A processing gas containing at least fluorocarbon and oxygen is continuously introduced into the processing chamber during the etching process, and a second electrode on which the object to be processed is placed among the first electrode and the second electrode arranged to face each other in the processing chamber. In an etching method in which two high-frequency powers are applied to an electrode to turn the processing gas into plasma, and an etching process is performed on a silicon oxide film layer formed on an object to be processed placed on the second electrode:
One high frequency power applied to the second electrode is pulsed power;
The other high-frequency power applied to the second electrode is lower than the frequency of the one high-frequency power;
In addition to the addition of oxygen to the processing gas, the amount of oxygen added is relatively increased or decreased during the etching process according to the increase in the aspect ratio of the holes formed in the silicon oxide film layer during the etching process. Let
An etching method, wherein the peak of the oxygen addition amount is increased while repeating the increase and decrease of the oxygen addition amount in a curvilinear and periodic manner. A processing gas containing at least fluorocarbon and oxygen is introduced into the processing chamber, and two high-frequency electric powers are applied to the second electrode on which the object to be processed is placed, out of the first electrode and the second electrode arranged to face each other in the processing chamber. In the etching method of applying the plasma into the processing gas and performing an etching process on the silicon oxide film layer formed on the target object placed on the second electrode:
  One high frequency power applied to the second electrode is pulsed power;
  The other high-frequency power applied to the second electrode is lower than the frequency of the one high-frequency power;
  Oxygen is intermittently added to the processing gas, and the peak of the amount of oxygen added increases as the aspect ratio of holes formed in the silicon oxide film layer increases during the etching process. Increased in stages during processing,
  An etching method, wherein the oxygen non-addition time is longer than the oxygen addition time. 9. The relationship between the change in the aspect ratio and the change in the plasma component is obtained in advance, and the amount of oxygen added is adjusted in accordance with the change in the plasma component. Etching method. The etching method according to claim 3, wherein the fluorocarbon gas is continuously supplied into the processing chamber during the etching process. The etching method according to claim 3, wherein the oxygen is added after the plasma is stabilized. A plasma processing apparatus for performing plasma processing on an object to be processed using the plasma processing method according to claim 1. The etching apparatus which performs an etching process to a to-be-processed object using the etching method as described in any one of Claims 3-11.

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