JP2015185714A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly controllable plasma processing apparatus and plasma processing method.SOLUTION: A plasma processing apparatus includes a processing chamber, a first electrode, a first power supply, a second electrode, a second power supply, a detector, and a processing section. The first power supply supplies high frequency power to the first electrode. The second electrode is provided in the processing chamber. The second power supply applies a first voltage to the second electrode in a plurality of first periods, and applies a second voltage in a plurality of second periods. The detector detects the light emitted from a workpiece irradiated with the plasma. The processing section estimates change of the workpiece, on the basis of the results detected in the detector during the plurality of first periods, and the results detected in the detector during the plurality of second periods.

Description

  Embodiments described herein relate generally to a plasma processing apparatus and a plasma processing method.

  In the manufacture of electronic parts, processing by plasma etching or the like is performed. There is a demand for processing with good controllability.

JP 2002-270574 A

  Embodiments of the present invention provide a plasma processing apparatus and a plasma processing method with high controllability.

  According to an embodiment of the present invention, there is provided a plasma processing apparatus including a processing chamber, a first electrode, a first power supply unit, a second electrode, a second power supply unit, a detection unit, and a processing unit. Is done. The first power supply unit supplies high frequency power to the first electrode to generate plasma in the processing chamber. The second electrode is provided in the processing chamber, and an object to be processed is disposed between the plasma and the second electrode. The second power supply unit applies a bias voltage to the second electrode. The bias voltage is a first voltage in a plurality of first periods, and is a second voltage lower than the first voltage in each of a plurality of second periods provided between the plurality of first periods. The detection unit detects light emitted from the target object irradiated with the plasma in the plurality of first periods and the plurality of second periods. The processing unit performs a change in the object to be processed based on a result detected in the plurality of first periods by the detection unit and a result detected in the plurality of second periods by the detection unit. presume.

1 is a schematic view illustrating a plasma processing apparatus according to a first embodiment. FIG. 2A to FIG. 2D are schematic views illustrating characteristics of the plasma processing apparatus. It is a schematic diagram which illustrates the characteristic of the plasma processing apparatus which concerns on 1st Embodiment. FIG. 5 is a flowchart illustrating the operation of the plasma processing apparatus according to the first embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a schematic view illustrating a plasma processing apparatus according to the first embodiment.
As shown in FIG. 1, the plasma processing apparatus 110 according to the embodiment includes a processing chamber 10, a first electrode 11, a first power supply unit 11p, a second electrode 12, a second power supply unit 12p, A detection unit 20 and a processing unit 30 are provided.

  The processing chamber 10 accommodates an object 70 to be processed. For example, a semiconductor wafer or the like is used as the object 70 to be processed. The object 70 is made of, for example, silicon (Si), oxygen (O), nitrogen (N), gallium (Ga), arsenic (As), phosphorus (P), boron (B), tungsten (W), silver ( Ag), aluminum (Al), indium (In), hafnium (Hf), iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), titanium (Ti) and tantalum (Ta) Including

A reaction gas 80 is introduced into the processing chamber 10. For example, an introduction port 10i is provided. The reaction gas 80 is introduced into the processing chamber 10 through the introduction port 10i. Examples of the reaction gas 80 include at least HBr, Cl ₂ , SiCl ₄ , BCl ₃ , CH ₄ , CH ₃ F, CH ₂ F ₂ , CHF ₃ , CF ₄ , NF ₃ , O ₂ , N ₂ , Ar, and He. Either one is used.

  For example, the first electrode 11 is provided on either the inside or the outside of the processing chamber 10. In this example, an ICP coil is used.

  The first power supply unit 11 p supplies high frequency power to the first electrode 11. The first power supply unit 11p generates plasma 80p in the processing chamber 10 on the first electrode 11 to which high-frequency power is supplied. For example, electrons 80e, ions 80i, and radicals 80r are generated from the reaction gas 80.

  When the object to be processed 70 is irradiated with the plasma 80p, the object to be processed 70 reacts with the ions 80i and radicals 80r, and the etching product 80ep is released. At that time, light 70l is emitted by the collision between the etching product 80ep and the electrons 80e in the plasma 80p.

  A second electrode 12 is provided in the processing chamber 10. The object 70 is disposed between the plasma 80p and the second electrode 12. The second power supply unit 12 p applies a bias voltage to the second electrode 12. In this example, the bias voltage is in the form of a pulse, for example. The bias voltage will be described later.

  The detection unit 20 detects light 70l generated when the etching product 80ep collides with the electron 80e. A light emitting probe or the like is used for the detection unit 20. The detection unit 20 detects light having a wavelength of, for example, 200 nanometers (nm) or more and 900 nm or less.

  The processing unit 30 obtains the result detected by the detection unit 20 and processes the result. In this example, the processing unit 30 is provided with a first storage unit 31, a second storage unit 32, and a calculation unit 35. The first accumulation unit 31 is, for example, a first data logger. The second accumulation unit 32 is a second data logger. These accumulation units accumulate (store) data. The computing unit 35 processes the data. For the processing unit 30 (calculation unit 35), for example, a computer (processing chip) is used.

  The processing unit 30 may control at least one of the first power supply unit 11p and the second power supply unit 12p.

FIG. 2A to FIG. 2D are schematic views illustrating characteristics of the plasma processing apparatus.
FIG. 2A illustrates the voltage supplied to the second electrode 12 from the second power supply unit 12p. In order to simplify the description, a description will be given using a voltage instead of the power supplied from the second power supply unit 12p to the second electrode 12. FIG. 2B illustrates light 701 emitted from the workpiece 70 in the plasma processing apparatus 110. The horizontal axis of these figures is the time ts. The vertical axis in FIG. 2A is the voltage Vp. The vertical axis in FIG. 2B is the light intensity Int.

  As shown in FIG. 2A, the second power supply unit 12p applies the first voltage V1 to the second electrode 12 in the first period tm1. The second power supply unit 12p applies the second voltage V2 to the second electrode 12 in the second period tm2.

  As shown in FIG. 2B, in the first period tm1 and the second period tm2, the intensity Int of the light 70l varies periodically.

  FIG. 2C illustrates the voltage Vp of the second power supply unit 12p in the plasma processing apparatus of the reference example. FIG. 2D illustrates light 70l generated when the etching product 80ep collides with the electrons 80e in the plasma processing apparatus of the reference example.

  As shown in FIG. 2C, in the reference example, the voltage Vp is constant in the first period tm1 and the second period tm2. As shown in FIG. 2D, there is no periodic change in the intensity of the light 70l in the first period tm1 and the second period tm2.

  As described above, when the voltage applied to the second power supply unit 12p varies between the first period tm1 and the second period tm2, the intensity of the light 70l varies. Therefore, it is difficult to estimate the change of the object 70 based on the light 70l generated when the etching product 80ep emitted from the object 70 irradiated with the plasma 80p collides with the electrons 80e. is there.

  At this time, the plasma processing apparatus 110 according to the present embodiment performs processing based on the result detected by the detection unit 20 during the first period tm1 and the result detected by the detection unit 20 during the second period tm2. The change of the body 70 is estimated.

  Thereby, the plasma processing apparatus 110 according to the embodiment can provide a plasma processing apparatus and a plasma processing method with high controllability.

  For example, the first accumulation unit 31 accumulates the results detected by the detection unit 20 during a plurality of first periods tm1. The second accumulation unit 32 accumulates the results detected by the detection unit 20 during a plurality of second periods tm2. The calculation unit 35 obtains the result accumulated in the first accumulation unit 31 and the result accumulated in the second accumulation unit 32 and estimates the change of the object 70 to be processed.

  For example, when it is estimated that the processing of the object 70 is completed, the processing unit 30 ends the operation of at least one of the first power supply unit 11p and the second power supply unit 12p.

  The length of the first period tm1 is T1. The length of the second period tm2 is T2. The units of T1 and T2 are the same as each other. For example, the unit is milliseconds.

  The intensity of the light (first light 70la) detected in the plurality of first periods tm1 is P1. The intensity of the light (second light 70 lb) detected in the plurality of second periods tm2 is P2. The units of P1 and P2 are the same as each other. At this time, the processing unit 30 derives a processing value P3 based on the strength P1 and the strength P2. The processing value P3 is given by the following equation (1).

P3 = P1−P2 × (T1 / T2) (1)

The processing unit 30 estimates, for example, a change in the object 70 based on the processing value P3, that is, a value corresponding to {P1-P2 (× T1 / T2)}.

FIG. 3 is a schematic view illustrating characteristics of the plasma processing apparatus according to the first embodiment.
The horizontal axis represents time ts, and the vertical axis represents light intensity Int.
As shown in FIG. 3, the intensity P1 of the first light 70la is higher than the intensity P2 of the second light 70lb. These intensities decrease with the passage of time ts. The processing value P3 is between the intensity P1 and the intensity P2. The processing value P3 decreases with the passage of time ts. For example, by observing the processing value P3, it is possible to estimate a change in the object 70 irradiated with the plasma 80p. For example, a threshold value is provided for the processing value P3. By comparing the threshold value with the process value P3, for example, it is possible to detect whether or not the process (for example, etching) in the object 70 has been completed.

  In the embodiment, each length of the first period tm1 is, for example, not less than 1 millisecond and not more than 10 milliseconds. Each of the plurality of second periods tm2 is, for example, not less than 1 millisecond and not more than 10 milliseconds. Each length of the plurality of first periods tm1 is, for example, not less than 0.1 times and not more than 10 times the length of each of the plurality of second periods tm2. For example, the second voltage V2 is lower than the first voltage V1. The second voltage V2 is, for example, 1/10 or less of the absolute value of the first voltage V1.

FIG. 4 is a flowchart illustrating the operation of the plasma processing apparatus according to the first embodiment.
As shown in FIG. 4, in the plasma processing apparatus 110, light is detected in a plurality of first periods tm1 and a plurality of second periods tm2 (step S110). This operation is performed by the detection unit 20, for example.

  Based on the results detected by the detection unit 20 during the plurality of first periods tm1 and the results detected by the detection unit 20 during the plurality of second periods tm2, changes in the object to be processed 70 are estimated (step S120). ). This operation is performed by the processing unit 30, for example.

  It is determined from the estimation result of the processing unit 30 whether the plasma processing on the object 70 is to be terminated (step S130). This operation is performed by the processing unit 30, for example. When it determines with the process part 30 complete | finishing, the plasma process to the to-be-processed object 70 is complete | finished. If it is determined that the processing unit 30 does not end, step S110 is performed.

  For example, the plasma etching apparatus according to the embodiment includes a plasma processing chamber, a pulse bias power source, a light emitting probe, a data logger, and an end point detector. An etching gas is introduced into the plasma processing chamber, and high frequency power is supplied between the insulating plate and the electrode. Plasma 80p is generated. The semiconductor memory device is etched by plasma 80p. The pulse bias power supply applies high-frequency power modulated in a pulse shape. The light emitting probe detects a light emission signal in the plasma 80p. The data logger tunes to the frequency of the pulse-modulated wave and detects each light emission signal in the ON / OFF state separately. The end point detector performs processing (for example, at least one of addition, subtraction, multiplication, and division) on the value of each light emission signal in the ON / OFF state. Then, for example, the etching end point is detected from the obtained value.

  For example, in the plasma etching process of the semiconductor memory device, for example, in order to suppress fluctuations in the etching amount of the processing apparatus, measurement of the type and density of radicals is measured from light emission in the plasma 80p. Based on this result, the etching end point is captured. That is, end point detection is performed.

  For example, semiconductor memory devices are being miniaturized, and bias pulse plasma etching is performed in the gate electrode processing step to enable high aspect processing. For example, a pulse-modulated wave is applied to an electrode holding an object to be etched (processed body, object to be processed). In this method, ON / OFF states of supplied power are repeated by applying a pulse. Thereby, an etching step using ions and a protective film forming step using radicals occur alternately. Thereby, for example, high aspect processing becomes possible.

  On the other hand, in this method, the amount of light emission accompanying the etching varies due to the influence of the supplied power that repeatedly turns on and off. For this reason, it is difficult to accurately grasp the etching end point.

  In the present embodiment, for example, in the bias pulse type plasma etching, light emission signals in ON / OFF states are separately extracted in conjunction with the period of the pulse modulation wave. Processing (for example, arithmetic processing) is performed on the extracted signal component. The end point is detected based on a change in value obtained from the result of the arithmetic processing. Thereby, the end point of etching is detected with high accuracy.

  For example, in the bias pulse type plasma etching, the ON-state period resulting from the etching is relatively shorter than that in a processing method with a constant bias. Thereby, light emission intensity and S / N ratio will fall. For this reason, if the method of detecting the etching end point is used for the end point detection of the bias pulse method using the time when the light emission amount falls below a desired value as a trigger, there is a possibility that proper end point detection cannot be performed. That is, for example, a film remains on the wafer. For example, excessive etching is performed.

  In the plasma processing apparatus according to the present embodiment, for example, following the period of a pulse-modulated wave applied from the pulse bias power source to the electrode of the plasma processing apparatus, the light emission signal in the ON / OFF state is converted into the first data logger and the first data logger. Separately measured by two data loggers, arithmetic processing is performed by a processing unit (for example, an end point detector) to separate signals resulting from etching, and an etching end point is detected.

  The present embodiment includes, for example, a plasma processing chamber, an insulating plate, an ICP coil, an electrode, a bias pulse power supply, a light emitting probe, a first data logger, a second data logger, and an end point detector. Including. An etching gas is introduced into the plasma processing chamber, and plasma 80p is generated by supplying high-frequency power between the insulating plate and the electrode via an ICP coil. At this time, a pulse-modulated wave of high-frequency power is supplied from the pulse bias power source to the electrode. Here, the etching target is a substrate. An etching gas is introduced into the plasma processing chamber, and plasma 80p is generated by supplying high-frequency power between the insulating plate and the electrode via an ICP coil. At this time, a pulse-modulated wave of high-frequency power is supplied from the pulse bias power source to the electrode.

  The light emission signal in the ON / OFF state is detected by the light emission probe, and the signals in the ON state and the OFF state are separately measured by the first data logger and the second data logger in synchronization with the frequency of the pulse modulation wave.

  A value (for example, a processing value P3) used for end point detection obtained by arithmetic processing by the end point detector is obtained by, for example, obtaining a ratio T1 / T2 between the ON state period T1 and the OFF state period T2, and a predetermined wavelength in the ON state. The light emission signal S1 and the light emission signal S2 having a predetermined wavelength in the OFF state can be calculated. At this time, the light emission signal S1 corresponds to the intensity P1, and the light emission signal S2 corresponds to the intensity P2. Therefore, the processing value P3 can be derived from the same expression as the expression (1). For example, the etching end point is detected when the processing value P3 falls below a desired value.

  According to the present embodiment, for example, even in bias pulse type plasma etching, a signal resulting from etching can be detected with high accuracy. Thereby, erroneous detection of the etching end point can be eliminated.

  In the plasma processing method according to the present embodiment, for example, in dry etching in which a substrate to be processed is processed using plasma 80p, a high-frequency bias voltage applied to an electrode on which the substrate to be processed is amplitude-modulated into a pulse waveform. Apply to. When detecting light of a predetermined wavelength of light emitted from the plasma 80p during etching, signal components in the ON state and the OFF state are extracted separately in synchronization with the period of the bias pulse. The end point of processing by the plasma 80p is detected based on a change in intensity obtained by arithmetically processing the extracted signal component. The light emission signal (process value P3) obtained by arithmetically processing the extracted signal components of the ON state and the OFF state is the light emission signals S1 and S2 (intensities P1 and P2) having a predetermined wavelength in the above-described ON state and OFF state and constants. Is obtained by a process combining at least one of addition, subtraction, multiplication and division.

  The plasma processing apparatus 110 according to the embodiment can provide a plasma processing apparatus with high controllability.

(Second Embodiment)
The present embodiment relates to a plasma processing method.
In the present embodiment, the object 70 is disposed between the plasma 80p generated in the processing chamber 10 and the bias electrode (second electrode 12), and a bias voltage is applied to the bias electrode. The bias voltage is the first voltage V1 in the plurality of first periods tm1, and is the second voltage V2 in the plurality of second periods tm2. Each of the plurality of second periods tm2 is provided between the plurality of first periods tm1. The second voltage V2 is lower than the first voltage V1.

  Light 701 emitted from the object 70 irradiated with the plasma 80p is detected in a plurality of first periods tm1 and a plurality of second periods tm2 (step S110).

  Based on the results detected in the plurality of first periods tm1 and the results detected in the plurality of second periods tm2, the change of the object to be processed 70 is estimated (step S120), and the plasma processing conditions are changed. To do. For example, the plasma processing is terminated (step S130).

In the present embodiment, the length of the first period tm1 is T1, and the length of the second period tm2 is T2. The units of T1 and T2 are the same as each other. The intensity of light detected in the plurality of first periods tm1 is P1, and the intensity of light detected in the plurality of second periods tm2 is P2. The units of P1 and P2 are the same as each other. At this time, based on the value according to {P1-P2 (xT1 / T2)}, the change of the to-be-processed object 70 is estimated. For example, when this value is smaller than a predetermined value, the plasma processing is terminated.
According to this embodiment, a plasma processing method with high controllability can be provided.

  According to the embodiment, a plasma processing apparatus and a plasma processing method with high controllability can be provided.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, those skilled in the art know the specific configuration of each element such as a processing chamber, a first electrode, a second electrode, a first power supply unit, a second power supply unit, a detection unit, and a processing unit included in the plasma processing apparatus. As long as the present invention can be carried out in the same manner and the same effects can be obtained by appropriately selecting from these ranges, they are included in the scope of the present invention.

  Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, all plasma processing apparatuses and plasma processing methods that can be implemented by those skilled in the art based on the plasma processing apparatus and the plasma processing method described above as embodiments of the present invention are also included in the gist of the present invention. As long as it is included, it belongs to the scope of the present invention.

  In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Processing chamber, 10i ... Inlet, 11 ... 1st electrode, 11p ... 1st power supply part, 12 ... 2nd electrode, 12p ... 2nd power supply part, 20 ... Detection part, 30 ... Processing part, 31 ... 1st Accumulation unit 32 ... second accumulation unit 35 ... calculation unit 70 ... object to be processed, 70l ... light, 70la ... first light, 70lb ... second light, 80 ... reaction gas, 80p ... plasma, 80e ... electron, 80i ... ion, 80r ... radical, 80ep ... etching product, 110 ... plasma treatment apparatus, Int ... strength, P1, P2 ... strength, P3 ... treatment value, T1, T2 ... period (length), V1, V2 ... first 1, second voltage, Vp ... voltage, tm1, tm2 ... first, second period, ts ... time

Claims (11)

A processing chamber;
A first electrode;
A first power supply for supplying high-frequency power to the first electrode to generate plasma in the processing chamber;
A second electrode provided in the processing chamber, wherein a target object is disposed between the plasma and the second electrode;
A second power supply unit configured to apply a bias voltage to the second electrode, wherein the bias voltage is a first voltage in a plurality of first periods, and each of the plurality of bias voltages is provided between the plurality of first periods. A second power supply unit that is a second voltage lower than the first voltage in the second period;
A detector that detects light emitted from the object irradiated with the plasma in the plurality of first periods and the plurality of second periods;
A processing unit that estimates a change in the object to be processed based on a result detected by the detection unit in the plurality of first periods and a result detected by the detection unit in the plurality of second periods; ,
A plasma processing apparatus comprising:   2. The plasma processing apparatus according to claim 1, wherein each of the plurality of first periods is 1 to 10 milliseconds, and each of the plurality of second periods is 1 to 10 milliseconds.   3. The plasma processing apparatus according to claim 1, wherein each of the plurality of first periods is 0.1 times or more and 10 times or less of each of the plurality of second periods. The length of the first period is T1, the length of the second period is T2, and the units of T1 and T2 are the same as each other.
When the light intensity detected in the plurality of first periods is P1, the light intensity detected in the plurality of second periods is P2, and the units of P1 and P2 are the same as each other,
The said processing part is a plasma processing apparatus as described in any one of Claims 1-3 which estimates the change of the said to-be-processed object based on the value according to {P1-P2 (* T1 / T2)}.   The plasma processing apparatus according to claim 4, wherein the processing unit estimates that the processing of the object to be processed is completed when the value is smaller than a predetermined value.   The plasma processing apparatus according to claim 4, wherein the processing unit ends the operation of at least one of the first power supply unit and the second power supply unit when it is estimated that the processing of the object to be processed is completed.   The plasma processing apparatus according to claim 1, wherein an absolute value of the second voltage is 1/10 or less of an absolute value of the first voltage. The processor is
A first accumulation unit that accumulates the results detected in the plurality of first periods by the detection unit;
A second accumulation unit for accumulating the results detected in the plurality of second periods by the detection unit;
The processing unit obtains the result stored in the first direct product unit and the result stored in the second storage unit, and calculates a change in the object to be processed;
The plasma processing apparatus of any one of Claims 1-7 containing these. An object to be processed is disposed between the plasma generated in the processing chamber and the bias electrode, and the bias electrode has a first voltage in a plurality of first periods, each of which is between the plurality of first periods. Applying a bias voltage that is a second voltage lower than the first voltage in a plurality of second periods provided;
Detecting light emitted from the object irradiated with the plasma in the plurality of first periods and the plurality of second periods;
A plasma processing method for estimating a change in the object to be processed and changing a plasma processing condition based on a result detected in the plurality of first periods and a result detected in the plurality of second periods. The length of the first period is T1, the length of the second period is T2, and the units of T1 and T2 are the same as each other.
When the light intensity detected in the plurality of first periods is P1, the light intensity detected in the plurality of second periods is P2, and the units of P1 and P2 are the same as each other,
The plasma processing method according to claim 9, wherein a change in the object to be processed is estimated based on a value according to {P 1 −P 2 (× T 1 / T 2)}.   The plasma processing method according to claim 10, wherein the plasma processing is terminated when the value is smaller than a predetermined value.

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