JP6019203B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing method and a plasma processing apparatus, and more particularly to a plasma processing method and a plasma processing apparatus related to plasma etching.

  One of plasma etching apparatuses currently used for mass production of semiconductor devices is an electron cyclotron resonance (hereinafter referred to as ECR) type apparatus. This plasma etching apparatus is characterized in that a high-density plasma can be generated by applying a magnetic field to the plasma and setting the magnetic field intensity so that the microwave frequency and the electron cyclotron frequency resonate.

  With the recent miniaturization of semiconductor elements, the thickness of the gate oxide film has become 2 nm or less. Therefore, it is necessary to realize controllability of the plasma etching process and a high selection ratio between the gate oxide film and the silicon film.

  As one of the techniques for realizing these high-precision plasma etching, there is a plasma etching method using pulse discharge. For example, Patent Document 1 discloses that a plasma is pulse-modulated while measuring a radical density in the plasma. A method for achieving high-precision etching by controlling the radical density is disclosed.

  Further, Patent Document 2 discloses that an oxide film on a processing wafer is subjected to dielectric breakdown by controlling the electron temperature in the plasma by synchronizing the on-off of the high frequency bias phase plasma applied to the wafer simultaneously with the pulse modulation of the plasma. A method of preventing this is disclosed.

  Patent Document 3 discloses a method for achieving high-speed anisotropic etching while preventing dielectric breakdown of an oxide film by applying pulse modulation of plasma at 10 to 100 μs and applying a high-frequency bias of 600 KHz or less to a wafer. Has been.

  Patent Document 4 discloses a method for reducing the ion temperature by controlling the radical by pulse-modulating the microwave for generating plasma and suppressing the instability of the plasma.

JP 09-185999 A JP 09-092645 A Japanese Patent Laid-Open No. 08-181125 Japanese Patent Laid-Open No. 06-267900

  Generally, the ECR type plasma etching apparatus has the following three problems.

  First, there is a case where a lower density region (low microwave power) is required depending on processing such as improvement in verticality. However, if the microwave power is decreased to reduce the plasma density, the generation of plasma will be reduced. There are challenges that will be difficult.

  The second problem is that there is an unstable region in which the emission of plasma is flickering visually or in measurements such as photodiodes depending on the microwave power when performing a discharge test with varying microwave power. There is. In this region, characteristics such as the etching rate are not reproducible. Therefore, the etching conditions are set to avoid the unstable region, that is, the process window is set to be narrow when performing the process development.

  It should be noted that the flickering of the discharge targeted in the present invention is that the electric field intensity distribution in the chamber changes depending on the microwave power, and the abnormal discharge is related to the chamber shape, for example, near the sample stage or near the microwave transmission window. Is a phenomenon in which blinking can be observed visually.

  Third, there is a high selectivity ratio region on the high microwave power side (high density region), but on the high microwave power side, a cut-off phenomenon occurs as the plasma density rises, and the plasma density is increased in the chamber. A mode jump occurs in which the distribution at the point changes. When this phenomenon occurs, the plasma emission intensity and the peak value of the bias voltage (Vpp voltage) change abruptly, and the distribution of the etching rate within the wafer surface changes greatly. It was.

  These three problems are common to the ECR type plasma etching apparatus using pulse discharge, but these three problems are not considered in the above-described prior art.

  Therefore, the present invention provides a plasma processing method and a plasma processing apparatus that can ensure a stable process region in a wide range from low microwave power to high microwave power.

  The present invention provides a plasma processing method for facilitating plasma generation in a region where plasma generation by continuous discharge is difficult, and for performing plasma processing on an object to be processed with the easily generated plasma. The plasma is easily generated by the pulse discharge that repeats the above, and the power of the high frequency power that generates the pulse discharge is the power that facilitates the generation of the plasma by the continuous discharge, and the duty ratio of the pulse discharge is: In the plasma processing method, the average power per cycle of the high-frequency power is controlled to be in a region where it is difficult to generate plasma by the continuous discharge.

  The present invention also includes a processing chamber for generating plasma therein, plasma generating means for generating the plasma, and a sample stage provided in the processing chamber for mounting a wafer, and etching the wafer with the plasma. In the plasma processing apparatus, the plasma generating means includes a power source that supplies power for generating the plasma, and on-off modulates the power of the power source and generates a plasma by continuously discharging the peak power at the on time. The plasma processing apparatus is characterized in that the time average value of the power is controlled by changing the duty ratio of the on / off modulation to a value that does not cause instability of the plasma when generated.

  The present invention also provides a plasma comprising a chamber in which a reactive gas can be introduced with a vacuum inside, a plasma generation power source for generating discharge plasma in the chamber, and a sample stage on which a wafer is placed in the chamber. In the processing apparatus, the output power of the plasma generation power source is pulse-modulated, and the peak power when on is set to a power value sufficiently higher than the mode jump region by continuous discharge, and the duty ratio of the pulse modulation is set. A plasma processing apparatus comprising a means for controlling a time average value of electric power by changing.

  According to the present invention, a stable process region can be secured in a wide range from low microwave power to high microwave power.

It is a schematic sectional drawing which shows an example of the plasma etching apparatus for enforcing the etching method of this invention. It is an output waveform of the magnetron 106 of the apparatus shown in FIG. It is a graph which shows the effect of the selection ratio improvement of this invention. It is a graph which shows the time average output dependence of the emission intensity of the oxygen atom of this invention of a microwave. It is a schematic sectional drawing of the plasma etching apparatus which performs feedback control which changes the duty ratio of pulse discharge for every wafer of Example 4 of this invention. It is sectional drawing of the fine pattern on the wafer which is a process target. It is a figure which shows the data of the correlation of the microwave electric power (duty ratio) and CD of Example 4 of this invention. It is a schematic sectional drawing which shows the plasma etching apparatus of Example 5 of this invention. It is a graph which shows the light emission intensity ratio of O (oxygen) / Br (bromine) with respect to the microwave of this invention. It is a graph which shows the selection ratio of the polysilicon / silicon oxide film with respect to the pulse microwave of this invention. It is a flowchart of the process of the apparatus which automates the measurement of the electric power which a mode jump produces.

  First, an example of a plasma etching apparatus for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a microwave ECR plasma etching apparatus using a microwave and a magnetic field as plasma generating means.

  The microwave ECR plasma etching apparatus includes a chamber 101 that can be evacuated to the inside, a sample stage 103 on which a wafer 102 that is an object to be processed is disposed, a microwave transmission window 104 made of quartz or the like provided on the upper surface of the chamber 101, and an upper portion thereof. Are provided with a waveguide 105, a magnetron 106, a solenoid coil 107 provided around the chamber 101, an electrostatic adsorption power source 108, and a high-frequency power source 109 connected to the sample stage 103.

  The wafer 102 is carried into the chamber 101 from the wafer carry-in port 110 and then electrostatically adsorbed to the sample stage 103 by the electrostatic adsorption power source 108. Next, process gas is introduced into the chamber 101. The inside of the chamber 101 is evacuated by a vacuum pump (not shown) and adjusted to a predetermined pressure (for example, 0.1 Pa to 50 Pa). Next, a microwave having a frequency of 2.45 GHz is oscillated from the magnetron 106 and propagated into the chamber 101 through the waveguide 105. The processing gas is excited by the action of the microwave and the magnetic field generated by the solenoid coil 107, and plasma 111 is formed in the space above the wafer 102. On the other hand, a bias is applied to the sample stage 103 by a high-frequency power source 109, and ions in the plasma 111 are accelerated and incident on the wafer 102 vertically. The high-frequency power source 109 can apply continuous high-frequency power or time-modulated intermittent high-frequency power to the sample stage 103.

  The wafer 102 is anisotropically etched by the action of radicals and ions from the plasma 111. Further, a pulse generator 112 is attached to the magnetron 106, whereby the microwave can be pulse-modulated in a pulse shape at a repetition frequency that can be arbitrarily set as shown in FIG.

  When the microwave ECR plasma etching apparatus performs plasma processing on the wafer 102, the control unit 113 controls the magnetron 106, the pulse generator 112, the solenoid coil 107, the high frequency power source 109, and the electrostatic adsorption power source 108, respectively. Yes.

The microwave ECR plasma etching apparatus used in the embodiments described below according to the present invention is a microwave ECR plasma etching apparatus for processing a wafer having a diameter of 300 mm. The inner diameter of the chamber 101 is 44.2 cm, and the wafer 102 and the microwave are etched. The distance from the transmission window 104 is 24.3 cm (volume of the space where plasma is generated is 37267 cm ³ ).

Next, in the first and second embodiments, the present invention for solving the problem that the generation of plasma becomes difficult when the microwave power is reduced to reduce the plasma density, which is the first problem. explain.
[Example 1]
Using the microwave ECR plasma etching apparatus shown in FIG. 1, the ignitability of plasma by the duty ratio and the time average output of the microwave was examined under the conditions shown in Table 1. Note that Vpp in Table 1 is a voltage difference from the peak value to the peak value of the high frequency voltage applied to the sample stage 103.

  Table 2 shows the results of the plasma generation investigation. In Table 2, “◯” indicates that plasma was stably generated, and “x” indicates that plasma could not be generated.

In the case of continuous discharge from Table 2, when the value obtained by dividing the time average output of the microwave by the volume of the inner wall of the chamber 101 is 0.011 W / cm ³ (about 400 W) or more, the plasma is stably generated. No longer generated. The reason why the plasma is not generated is that the energy required for free electrons to ionize the molecules of the etching gas is not supplied. However, in the case of discharge by pulsed microwave, plasma is generated even if the value obtained by dividing the time average output of the microwave by the volume in which the plasma is generated is smaller than 0.011 W / cm ³ .

  The difference in plasma generation between the continuous discharge and the pulsed microwave discharge is due to the following reason.

  During a period of several microseconds when the microwave is on, free electrons ionize or dissociate other atoms and molecules with the energy acquired from the microwave to generate a plasma 111. When the microwave is turned off, most free electrons are trapped by atoms and molecules within a few μsec, and most of the plasma 111 becomes anions and cations. Since anions and cations are larger in mass than electrons, they collide and neutralize, and it takes several tens of milliseconds for the plasma 111 to disappear. Therefore, if the microwave off time is shorter than 10 ms, the microwave on period starts before the plasma 111 disappears, and the plasma 111 is maintained.

Therefore, in other words, the result shown in Table 2 is more than the minimum power necessary for stably generating the plasma by the continuous discharge during the on period of the pulse microwave (that is, 0.011 W / cm ³ or more). Then, it can be said that the discharge can be stably generated even when the time average output of the pulse microwave is 0.011 W / cm ³ or less. Further, if the pulse microwave off period is set to 10 ms or less, even in the region where the time average output of the pulse microwave is 0.011 W / cm ³ or less, the discharge can be generated more stably than the above-described plasma processing method. I can say that.

Further, an inert gas such as argon gas (Ar: ionization energy 1520.6 kJ / mol) and nitrogen gas (N ₂ : ionization energy 1402 kJ / mol) is added, or ionization other than the above inert gas is easy to ionize. It is easy to generate a stable discharge by adding gas. The types of other gases, the flow rate of each gas, the processing pressure, the RF bias value, and the like do not give any special limitation to the effect of this embodiment.

  Next, a wafer with a polysilicon film as a whole surface and a wafer with a silicon oxide film as a whole surface were etched under the conditions shown in Table 1, and the selection ratio was determined from the ratio of the respective scraping amounts. The result is shown in FIG. In addition, “%” in FIG. 3 means a duty ratio when pulse discharge is performed.

FIG. 3 shows that when the duty ratio is set to 50% or less and the microwave time average output is set to 400 W (0.011 W / cm ³ ) or less, the selection ratio increases from continuous discharge. This is because if the time average output of the microwave is small, the number of free electrons in the chamber 101 is reduced, and the reduced amount of electrons excites atoms and molecules, thus increasing the density of radical species and improving the selectivity. It is thought that.

  Further, the selection ratio is further increased by controlling the oxygen gas under the conditions in Table 1 to 1 ml / min or more and 10 ml / min or less.

  In addition, the present embodiment is an example applied to a microwave ECR plasma etching apparatus, but can also be applied to a capacitive coupling type or inductively coupled type plasma etching apparatus. As described above, according to the plasma processing method of the present invention, the high frequency power during the pulse discharge on period is set to the high frequency power that can stably generate the continuous discharge plasma, and the pulse discharge off period is set to 10 ms or less. This is a method of processing an object to be processed by pulse discharge. By such a plasma processing method of the present invention, it is possible to stably generate plasma even in a region where the power for generating plasma, where it is difficult to stably generate plasma, is small.

Furthermore, in the plasma processing method of the present invention, when the duty ratio of the pulse discharge is set to 50% or less, the selectivity of the etching rate of the polysilicon film with respect to the silicon oxide film can be improved compared to the continuous discharge.
[Example 2]
Next, another embodiment of the present invention described in Embodiment 1 will be described.

  When pulse discharge plasma treatment is performed under the conditions shown in Table 3, the performance of removing carbon-based deposits and resist is improved over continuous discharge.

  FIG. 4 shows the results of measuring the ratio of the emission intensity of oxygen to the emission intensity of argon by adding 5 ml / min of argon gas to the conditions shown in Table 3.

As can be seen from FIG. 4, the emission intensity of oxygen atoms increases from a value lower than 0.011 W / cm ³ , which is a value obtained by dividing the time average output of the microwave by the volume at which the plasma is generated.

  That is, when the pulse discharge of the present invention is performed under the conditions shown in Table 3, the oxygen radical density increases, and the effect of removing the carbon-based deposits and removing the resist is improved.

Next, when performing a discharge test by changing the power of the microwave, which is the second problem, the emission of the plasma appears to flicker visually or in measurements such as photodiodes depending on the microwave power. The present invention for solving the problem that the region exists will be described in the third to fifth embodiments.
[Example 3]
For the plasma etching process of this example, a microwave ECR plasma etching apparatus shown in FIG. 1 was used. Next, an example of conditions for etching the polysilicon film 302 is shown in Table 4. Under this condition, the polysilicon film 302 can be etched with a high selectivity with respect to the underlying oxide film 303.

  Table 5 shows the result of measuring the flicker by detecting the light emission from the plasma 111 with a photodiode while changing the microwave for generating the plasma under the conditions shown in Table 4. The microwave power is compared with the case of continuous discharge and the case where the power is controlled by changing the duty ratio by performing on / off modulation at a frequency of 1 KHz by setting the power during the microwave on period to 1500 W. In Table 5, “◯” indicates no discharge flicker, and “X” indicates discharge flicker. Etching cannot be performed in a state where the discharge flickers.

  In continuous discharge, flicker occurs from 900 W to 1100 W, but the flicker of discharge can be eliminated by on / off control of the microwave. The cause is that the plasma 111 generated by instantaneous power is set to be in a stable region, and further, when a pulse discharge is performed with the plasma 111 of a gas that tends to be a negative ion such as a halogen gas, electrons are several tens of μs when turned off. Since the negative ions and positive ions are involved in maintaining the discharge for several ms thereafter, the flicker is eliminated unlike the state of the sheath of the plasma 111 generated at the interface between the chamber wall and the plasma 111. It is estimated to be.

  Since the time until the plasma 111 disappears is several tens of ms, when the off time is set to 10 ms or less, the plasma 111 is maintained on until the plasma 111 disappears.

  The flickering power region of the plasma 111 depends on conditions. Therefore, in the etching under different conditions, first, the microwave power is changed by continuous discharge, and as in Table 5, the region where the discharge flickers is confirmed, and the power during the microwave ON period is larger than the power that causes the flicker. Flicker can be eliminated by setting the microwave sufficiently large and performing on / off pulse modulation of the microwave at a frequency at which the off time is 10 ms or less.

Note that the microwave power shown in Table 5 changes according to the volume of the chamber 101 when the size of the chamber 101 changes, and 1500 W corresponds to about 0.04 W / cm ³ in terms of the microwave power per unit volume.

The presence of an unstable region in the discharge is not limited to the microwave plasma etching apparatus, and there is a similar problem in the inductively coupled or capacitively coupled plasma etching apparatus. Stability can be avoided.
[Example 4]
Next, an embodiment relating to a method of controlling an etching processing dimension (hereinafter referred to as “CD”) that can be performed by on / off modulation of the plasma 111 will be described. FIG. 5 shows the etching conditions of the wafer 102 being processed or the wafer 102 to be processed next based on this monitor value by measuring the emission intensity of the plasma 111 or the etching process end time obtained from the change of the emission intensity. 1 shows a schematic diagram of a plasma etching apparatus whose mechanism is added to the microwave ECR plasma etching apparatus shown in FIG.

  The light receiving unit 202, the CD calculation unit 203, the recipe calculation unit 205, the first database 206, the second database 204, and the etching control PC 207 shown in FIG. 5 are connected to each other via communication means. FIG. 6 is a cross-sectional view of a fine pattern on a wafer 102 to be processed. A mask 301 made of silicon nitride or the like obtained by processing a polysilicon film 302 on a silicon substrate 304 and an underlying oxide film 303 into a fine pattern, and It shows a state of etching in the same pattern.

In dry etching, processing such as shown in FIG. 6 is normally continuously processed for one lot (25 sheets). The processed line width (hereinafter referred to as “CD”) needs to be within a certain tolerance during continuous processing. However, in some cases, etching reaction products or the like adhere to the chamber 101, the plasma state changes with time, and the CD variation does not fall within an allowable value.

  In this embodiment, the plasma 111 is modulated on and off, and the duty ratio is changed for each wafer, thereby suppressing the CD variation within an allowable value. Normally, the CD changes depending on the bias power applied to the wafer 102 and the plasma density, that is, the microwave power, so that the CD can be changed by changing the microwave power.

  Next, a specific method will be described. The end point of the etching of the polysilicon film 302 shown in FIG. 6 is detected by the optical fiber 201 and the light receiving unit 202 of the emission of reaction products in the plasma 111, for example, 426 nm light of silicon. There is a correlation between the etching end time and the CD, and the relationship between the etching end time and the CD is stored in the second database 204. The CD calculation unit 203 calculates an estimated value of the CD of the wafer 102 from the etching end time. The difference between the calculated CD and the CD target value is calculated, and this difference value is sent to the recipe calculation unit 205.

  The recipe calculation unit 205 has a first database 206 in which the correlation data between the microwave power (duty ratio) and the CD shown in FIG. 7 is stored, and makes the difference from the target value of the CD zero. The variable of the microwave power required for the calculation is calculated. For example, if the target CD is 30 nm and the n-th CD is 30 + a (nm) as shown in FIG. 7, the average micro is used to make the n + 1-th target CD, that is, to reduce a (nm). The power of the wave, that is, the duty ratio is increased by d (%).

The duty ratio calculated from the first database 206 is sent to the etching control PC 207 and is set to this value when the next wafer 102 is processed, and etching is performed. At this time, if the plasma 111 is continuously discharged, the microwave power value corrected so that the CD difference becomes zero may enter an unstable region of the plasma 111 shown in Table 5, which may cause etching. It will cause trouble. As described in the third embodiment, the problem of instability of the plasma 111 can be solved by controlling the microwave power by modulating the on / off of the plasma 111 and changing its duty ratio.
[Example 5]
Next, in order to prevent discharge instability, a method of expanding the stability margin when used in combination with the present invention will be described with reference to FIG. First, in order to stabilize the potential of the plasma 111, it is desirable to provide a ground surface 401 through which a direct current flows in a portion in contact with the plasma 111.

Usually, the inner wall of the chamber 101 is subjected to stabilization treatment such as alumite or yttrium oxide, but since these materials are insulators, direct current does not flow. A part of the portion in contact with the plasma 111 is peeled off these insulating films, or a conductor is inserted, and the potential of the plasma 111 is stabilized by further bringing the conductor portion to the ground potential, so that the discharge becomes more stable. The area of the DC ground plane 401 is preferably 10 cm ² or more.

Next, it is desirable to set the pressure of the process gas between 0.1 and 10 Pa. If the pressure is too low, the mean free path of electrons becomes longer, increasing the chance of disappearing at the wall before ionization occurs, causing the plasma 111 to become unstable. On the other hand, if the pressure is too high, the ignitability is poor and instability is likely to occur.

  Furthermore, it is desirable that the shapes of the chamber 101 and the sample stage 103 are reduced as much as possible in a portion where the electric field is locally strong. That is, it is preferable that the corner portion 402 be a curved line having a radius of 5 mm or more without providing sharp irregularities.

  Next, there is a high selectivity ratio region on the high microwave power side (high density region), which is the third problem. On the high microwave power side, a cut-off phenomenon occurs as the plasma density increases. In the sixth and seventh embodiments, the present invention for solving the problem that a mode jump in which the distribution of the plasma density in the chamber changes occurs will be described.

In addition, the plasma etching process in Example 6 and Example 7 was performed using the microwave ECR plasma etching apparatus shown in FIG.
[Example 6]
As shown in FIG. 3, the polysilicon / silicon oxide film selection ratio increases even in the region where the average microwave power is large (800 W or more). In order to explain the reason, FIG. 9 shows the relationship between the microwave power and the emission intensity ratio of O (oxygen) and Br (bromine). As can be seen from FIG. 9, the emission intensity of O (oxygen), that is, the density of O radicals increases on the high microwave side. For this reason, it is considered that the silicon oxide film is prevented from being scraped and the selectivity is improved.

  However, when the microwave power value is further increased, as shown in FIG. 9, in CW (continuous discharge), when the microwave power value is 900 W or more, the emission intensity suddenly changes, that is, the mode jump phenomenon (at CW) ) 500 occurs. For this reason, the high microwave region cannot be used in continuous discharge.

  Therefore, in the present invention, the duty ratio is controlled by pulsing the microwave and setting the peak power at the time of turning on sufficiently higher than the power value at which the mode jump occurs. It can be seen that when the duty is 65% or less, the emission intensity ratio (FIG. 9) does not change abruptly, that is, the mode jump is avoided.

The reason is estimated as follows. In CW (continuous discharge), the electron density increases with the microwave power value, and the mode changes from the power value that reaches the density at which the vibration of the plasma 111 and the frequency of the electromagnetic wave resonate. On the other hand, in the pulsed microwave, most of free electrons are trapped by atoms and molecules within several μsec when turned off, and most of the plasma 111 becomes anions and cations. For this reason, in the pulse microwave which repeats ON / OFF, the electron density does not increase.

  FIG. 10 shows a selection ratio result obtained by evaluating the high microwave power side using the conditions shown in Table 1. In CW (continuous discharge), the selection ratio decreases (becomes unstable) due to the effect of mode jump when the microwave power value is 900 W or more, but by pulsing the microwave, the high microwave power side is used, A high selectivity can be obtained.

  In general, in pulse discharge, it is known that the electron density is attenuated by one digit or more after 50 μs after power-off. Accordingly, if the discharge is pulsed and the pulse repetition frequency and the duty ratio are set so that the OFF time is 50 μs or more, the mode jump can be sufficiently avoided.

As described above, in the present invention, the mode modulation generated on the high microwave power side can be avoided and the effective process area for etching can be expanded by pulse-modulating the microwave.
[Example 7]
Next, a method and apparatus for automatically avoiding this mode jump area will be described. As shown in FIG. 9, the mode jump occurs in a high power region where the microwave power is about 900 W or more. However, since the density of the plasma 111 varies depending on the gas pressure and the type of gas, the power at which the mode jump occurs depends on these conditions. Depends on different.

  A method for avoiding this is to first measure the power value at which the mode jump occurs under the conditions to be used in advance, and the apparatus stores the etching conditions and the power at which the mode jump occurs under those conditions, and uses that condition. Has a function of automatically pulse-modulating the microwave power. An apparatus having this function can prevent an erroneous operation using the mode jump area by mistake.

  Furthermore, an apparatus for automating the measurement of power that causes a mode jump in advance will be described. FIG. 11 shows a flow chart of processing of an apparatus for automating measurement of power at which mode jump occurs. Normally, etching is performed in units of lots (25 sheets), but before the lots are processed, the dummy wafer processing 501 is performed under the same conditions as those to be processed.

  After that, the lot processing 502, the cleaning 503 of the chamber 101 by the oxygen plasma 111, etc. are followed. The dummy wafer processing 501 includes a microwave power automatic scan measurement 504 that is a step of automatically scanning from a set value of microwave power, for example, from 800 W to 1200 W and measuring the emission intensity of the plasma 111 during this period with a photodiode or the like.

  Next, the personal computer 507 for etching apparatus control performs a mode jump power identification 505 for extracting and storing a region where the emission intensity changes suddenly from this data, and a region where the microwave power is mode jumped when a recipe is input. A function of performing automatic recipe generation 506 that automatically performs pulse modulation in the case of This function allows the operator to perform etching without being bothered by the mode jump region.

The physical quantity measured when the microwave power is scanned is not limited to the light emission intensity, and the same function can be achieved as long as the quantity changes rapidly corresponding to the mode jump such as the peak value (Vpp) of the bias voltage. Further, the absolute value of the microwave power described in the present invention largely varies depending on the size of the chamber 101, that is, the diameter of the wafer 102 to be processed. As a standard, if a value normalized by the volume of the chamber 101 is used, it can be converted into an amount independent of the volume of the chamber 101. For example, in the above embodiment, 900 W corresponds to 0.024 W / cm ³ .

DESCRIPTION OF SYMBOLS 101 Chamber 102 Wafer 103 Sample stage 104 Microwave transmission window 105 Waveguide 106 Magnetron 107 Solenoid coil 108 Electrostatic adsorption power supply 109 High frequency power supply 110 Wafer carry-in 111 Plasma 112 Pulse generator 113 Control part 201 Optical fiber 202 Light receiving part 203 CD calculating part 204 Second database 205 Recipe calculation unit 206 First database 207 Etching control PC
301 Mask 302 Polysilicon film 303 Oxide film 304 Silicon substrate 401 Ground surface 402 Corner portion 500 Mode jump phenomenon (during CW)
501 Dummy wafer processing 502 Lot processing 503 Cleaning 504 Microwave power automatic scan measurement 505 Mode jump power identification 506 Automatic recipe generation

Claims (5)

A plasma processing apparatus comprising: a processing chamber in which an object to be processed is subjected to plasma processing; a high-frequency power source that supplies high-frequency power for generating plasma; and a sample stage that is disposed in the processing chamber and on which the object to be processed is placed In
The range of the high frequency power in which the generation of plasma in the case of continuous discharge becomes difficult and the range of the high frequency power in which the generation of plasma in the case of continuous discharge becomes easy are obtained in advance and the plasma in the case of continuous discharge obtained in advance. A control unit that modulates high-frequency power in a range of high-frequency power that is difficult to generate with a pulse that repeatedly turns on and off,
The high-frequency power during the on-period of the pulse is set to a value in the range of the high-frequency power that facilitates plasma generation in the case of continuous discharge, which is obtained in advance.
The duty ratio of the pulse is set such that the average high frequency power per cycle of the pulse is a value in the range of the high frequency power in which plasma generation is difficult in the case of continuous discharge. A plasma processing apparatus. The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein an off period of the pulse is 10 ms or less. The plasma processing apparatus according to claim 1,
A value obtained by dividing the average high frequency power by the volume of the processing chamber is set to 0.011 W / cm ³ or less. The plasma processing apparatus according to claim 1,
The object to be processed has a polysilicon film and a silicon oxide film,
The plasma processing apparatus, wherein the pulse-modulated plasma is generated using hydrogen bromide gas and oxygen gas. The plasma processing apparatus according to claim 4, wherein
A plasma processing apparatus, wherein the flow rate of the oxygen gas is 1 ml / min to 10 ml / min.

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