JP2012015307A - Method of manufacturing semiconductor device, power supply circuit, and plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device in which variation in processing size can be reduced between different plasma processing apparatus, and to provide a power supply circuit, and a plasma processing apparatus.SOLUTION: The method of manufacturing a semiconductor device using a plasma processing apparatus comprises: a mounting step of mounting a semiconductor substrate on an electrode in a processing chamber; a generation step of supplying power from a power supply circuit to the electrode and generating plasma in a space of the processing chamber separated from the electrode; a detection step of detecting a bias voltage which is the difference between the potential of plasma generated at the generation step and the potential of the electrode to which power is supplied; a correction step of correcting the capacity value of the power supply circuit so that a bias voltage detected at the detection step matches a target value; and a processing step of processing the semiconductor substrate by using the plasma processing apparatus in a state where the bias voltage detected at the detection step after the correction step matches the target value.

Description

  Embodiments described herein relate generally to a method for manufacturing a semiconductor device, a power supply circuit, and a plasma processing apparatus.

  In recent years, with the progress of miniaturization of semiconductor devices, improvement in processing accuracy in the processing technology of semiconductor devices is desired. In particular, in an etching technique using a plasma processing apparatus such as a RIE (Reactive Ion Etching) apparatus, even in the same processing conditions of the same model, variations in processing dimensions and etching amounts between different plasma processing apparatuses are It tends to be a level that cannot be ignored for the required machining accuracy.

JP 2007-227623 A JP-A-3-54825 JP 2004-96066 A JP-A-3-28370

  Embodiments of the present invention provide, for example, a semiconductor device manufacturing method, a power supply circuit, and a plasma processing apparatus that can reduce variations in processing dimensions and etching amounts between plasma processing apparatuses of the same model and the same processing conditions. Objective.

  According to an embodiment, there is provided a method of manufacturing a semiconductor device using a plasma processing apparatus having an electrode disposed in a processing chamber and a power supply circuit for supplying power to the electrode, wherein the semiconductor is connected to the electrode in the processing chamber. A placing step of placing a substrate; a generating step of supplying power to the electrode from the power supply circuit; and generating plasma in a space separated from the electrode in the processing chamber; and plasma generated in the generating step Detecting a bias voltage that is a difference between the potential of the electrode and the potential of the electrode to which power is supplied, and a capacitance value of the power supply circuit so that the bias voltage detected in the detecting step matches a target value. A correction step for correcting, and the bias voltage detected in the detection step after the correction step is matched with the target value using the plasma processing apparatus. The method of manufacturing a semiconductor device characterized by comprising a processing step of processing the conductor substrate is provided.

  Further, according to another embodiment, an electrode disposed in the processing chamber and on which the substrate to be processed is placed, a power supply circuit for supplying power to the electrode, and a space separated from the electrode in the processing chamber A plasma generating unit for generating plasma, and a detecting unit for detecting a bias voltage which is a difference between the potential of the plasma generated by the plasma generating unit and the potential of the electrode supplied with power by the power supply circuit A power supply circuit for supplying electric power to the electrode in the plasma processing apparatus provided with a generator for generating electric power to be supplied to the electrode, and a bias voltage detected by the detector coincides with a target value Thus, there is provided a power supply circuit comprising a correction unit that corrects the capacitance value of the generation unit.

  Further, according to another embodiment, an electrode disposed in the processing chamber and on which the substrate to be processed is placed, a power supply circuit for supplying power to the electrode, and a space separated from the electrode in the processing chamber A plasma generating unit for generating plasma, and a detecting unit for detecting a bias voltage which is a difference between the potential of the plasma generated by the plasma generating unit and the potential of the electrode supplied with power by the power supply circuit The power supply circuit includes: a generating unit that generates power to be supplied to the electrode; and a correcting unit that corrects a capacitance value of the generating unit so that a bias voltage detected by the detecting unit matches a target value; And the plasma processing apparatus processes the substrate to be processed in a state where a bias voltage detected by the detection unit matches the target value. There is provided.

The figure which shows the structure of the plasma processing apparatus concerning 1st Embodiment. The figure which shows the structure of the correction | amendment part in 1st Embodiment. 3 is a flowchart showing a method for manufacturing a semiconductor device using the plasma processing apparatus according to the first embodiment. The figure which shows the structure of the plasma processing apparatus concerning 2nd Embodiment. The figure which shows the structure of the correction | amendment part in 2nd Embodiment. The figure which shows the data structure of the memory | storage part in 2nd Embodiment. 9 is a flowchart showing a method for manufacturing a semiconductor device using a plasma processing apparatus according to a second embodiment. The figure which shows the structure of the correction | amendment part in 3rd Embodiment. The figure which shows the data structure of the memory | storage part in 3rd Embodiment. 9 is a flowchart showing a method for manufacturing a semiconductor device using a plasma processing apparatus according to a third embodiment. The figure which shows the structure of the plasma processing apparatus concerning 4th Embodiment. The figure which shows the data structure of the memory | storage part in 4th Embodiment. 9 is a flowchart showing a method for manufacturing a semiconductor device using a plasma processing apparatus according to a fourth embodiment. The figure which shows operation | movement of the plasma processing apparatus concerning a comparative example.

  Hereinafter, a plasma processing apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

(First embodiment)
A plasma processing apparatus 1 according to a first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of a plasma processing apparatus 1 according to the first embodiment.

  The plasma processing apparatus 1 includes a processing chamber 50, an electrode 10, a power supply circuit 20, a plasma generation unit 80, and a detection unit 90.

  The processing chamber 50 is a chamber for generating plasma PL therein, and is formed by a processing container. The processing container is configured so that processing gas can be supplied from a supply source (not shown) to the processing chamber 50, and the processed processing gas can be exhausted from the processing chamber 50 to an exhaust device (not shown). It is configured as follows.

  The electrode 10 is disposed on the bottom side in the processing chamber 50 so as to be insulated from the processing container via an insulating material (not shown). A substrate to be processed (for example, a semiconductor substrate) WF is placed on the electrode 10. The electrode 10 is made of metal, for example.

The power supply circuit 20 generates high frequency power and supplies the high frequency power to the electrode 10. This high-frequency power accelerates ions (for example, F ⁺ , CF 3 ^+, etc.) generated together with radicals from the processing gas when plasma PL is generated in the processing chamber 50 to the electrode 10 side (target substrate WF side). It is electric power to make it. The frequency of the high frequency power is, for example, 13.56 MHz. The internal configuration of the power supply circuit 20 will be described later.

The plasma generator 80 generates plasma PL in a space 51 separated from the electrode 10 in the processing chamber 50. Specifically, the plasma generation unit 80 includes a high frequency power supply 81, a matching box 84, an antenna coil 82, and a dielectric wall 83. The high frequency power supply 81 generates high frequency power and supplies it to the antenna coil 82. The matching box 84 has, for example, a variable capacitor and a variable coil. The matching box 84 uses a variable capacitor and a variable coil to adjust the impedance (impedance matching) so that the impedance on the high frequency power supply 81 side with respect to the matching box 84 and the impedance on the antenna coil 82 side with respect to the matching box 84 become equal. To do. The antenna coil 82 generates an electromagnetic wave (high frequency magnetic field) using the high frequency power supplied in a state where impedance matching is performed. The electromagnetic wave generated by the antenna coil 82 passes through the dielectric wall 83 and is introduced into the space 51 in the processing chamber 50. In the space 51 in the processing chamber 50, the processing gas is discharged to generate plasma PL, and ions (for example, F ⁺ , CF 3 ^+, etc.) are generated from the processing gas together with radicals. The dielectric wall 83 also serves as the upper wall portion of the processing container.

  The detection unit 90 detects a bias voltage Vb that is a difference between the potential Vpl of the plasma PL generated by the plasma generation unit 80 and the potential Ve of the electrode 10 supplied with power by the power supply circuit 20.

  Specifically, the detection unit 90 measures the potential of the detection terminal 92 and calculates a potential difference between the potential of the detection terminal 92 (that is, the potential of the electrode 10) and the side wall portion in the vicinity of the plasma PL (that is, the ground potential) in the processing container. Measured as bias voltage Vb. At this time, the potential difference between the plasma PL potential Vpl and the processing chamber wall is small and can be ignored.

Alternatively, as a more accurate method, the detection unit 90 includes a detection terminal 91 that extends to the space 51 in the processing chamber 50 and a detection terminal 92 that is electrically connected to the electrode 10. The detection unit 90 detects the potential Vpl of the plasma PL via the detection terminal 91 and detects the potential Ve of the electrode 10 via the detection terminal 92. And the detection part 90 is
Vb = Vpl-Ve
Thus, the bias voltage Vb is obtained. The detector 90 supplies the bias voltage Vb thus detected to the power supply circuit 20.

  Next, the internal configuration of the power supply circuit 20 will be described with reference to FIG.

The power supply circuit 20 includes a generation unit 40 and a correction unit 30. The generator 40 generates electric power to be supplied to the electrode 10. Specifically, the generation unit 40 includes a high frequency power supply 43, a matching box 42, and a blocking capacitor 41. The high frequency power supply 43 generates high frequency power. The matching box 42 has, for example, a variable capacitor and a variable coil. The matching box 42 uses a variable capacitor and a variable coil to adjust the impedance (impedance matching) so that the impedance on the high frequency power supply 43 side with respect to the matching box 42 and the impedance on the blocking capacitor 41 side with respect to the matching box 42 are equal. To do. The blocking capacitor 41 supplies a high frequency component of the high frequency power supplied from the high frequency power supply 43 to the electrode 10 in a state where impedance matching is performed. As a result, the electrode 10 is negatively charged while the plasma PL is positively charged, and ions (for example, F ⁺ , CF 3 ^+, etc.) are generated on the electrode 10 side (target substrate WF side) due to the potential difference between them, ie, the bias voltage Vb. ).

  The correction unit 30 receives a signal indicating the bias voltage Vb detected by the detection unit 90 from the detection unit 90. The correction unit 30 corrects the capacitance value of the power supply circuit 20 by supplementing the capacitance of the generation unit 40 so that the bias voltage Vb indicated by this signal matches the target value Vt. The target value Vt is a value set in advance according to predetermined processing conditions (gas type, gas pressure, etc.) for the object to be processed, and is a value common to the plasma processing apparatuses. The feedback operation including the detection operation of the bias voltage Vb by the detection unit 90 and the correction operation of the capacitance value of the power supply circuit 20 by the correction unit 30 is repeatedly performed, so that the bias voltage Vb matches the target value Vt. Adjusted. Thereby, the plasma processing apparatus 1 processes (for example, etching process) the to-be-processed substrate WF in the state in which the bias voltage Vb detected by the detection unit 90 matches the target value Vt.

  Next, the internal configuration of the correction unit 30 will be described with reference to FIG. FIG. 2 is a diagram illustrating an internal configuration of the correction unit 30.

  The correction unit 30 includes a variable capacitance unit 35, a comparison unit 33, and a change unit 34. The variable capacitance unit 35 is configured to be able to change its capacitance value according to the received control signal. The comparison unit 33 receives a signal indicating the bias voltage Vb detected by the detection unit 90 from the detection unit 90. In addition, the target value Vt is set in the comparison unit 33 in advance. The comparison unit 33 compares the bias voltage Vb indicated by the signal received from the detection unit 90 with the target value Vt, and supplies the comparison result to the change unit 34. The changing unit 34 changes the capacitance value of the variable capacitance unit 35 according to the supplied comparison result.

  Specifically, the variable capacitance unit 35 includes a variable capacitance element (first variable capacitance element) 31 and a variable capacitance element (second variable capacitance element) 32. The variable capacitance element 31 is connected in series with the electrode 10 and the generator 40. For example, the variable capacitance element 31 has its electrode 31 a electrically connected to the electrode 10 and its electrode 31 b electrically connected to the generator 40. The variable capacitance element 32 is connected to the electrode 10 in parallel with the generator 40. For example, in the variable capacitance element 32, the electrode 32a is electrically connected to the electrode 10 and the electrode 31a, and the electrode 32b is connected to the ground voltage. Since one end of the generator 40 is connected to the ground voltage, the variable capacitance element 32 is equivalently connected in parallel with the generator 40.

  When the comparison unit 33 indicates that the bias voltage Vb indicated by the signal is higher than the target value Vt, the changing unit 34 performs at least an operation of increasing the capacitance value of the variable capacitor 32. As a result, the capacitance value of the variable capacitance element 32 connected in parallel with the generation unit 40 increases, and the capacitance value of the power supply circuit 20 increases so that the bias voltage Vb decreases. That is, the capacitance value of the power supply circuit 20 is corrected so that the bias voltage Vb approaches the target value Vt. Note that the changing unit 34 may further perform an operation of reducing the capacitance value of the variable capacitance element 31.

  When the comparison unit 33 indicates that the bias voltage Vb indicated by the signal is lower than the target value Vt, the changing unit 34 performs at least an operation of increasing the capacitance value of the variable capacitance element 31. As a result, the capacitance value of the variable capacitance element 31 connected in series with the generation unit 40 increases, so that the capacitance value of the power supply circuit 20 decreases so that the bias voltage Vb increases. That is, the capacitance value of the power supply circuit 20 is corrected so that the bias voltage Vb approaches the target value Vt. Note that the changing unit 34 may further perform an operation of reducing the capacitance value of the variable capacitance element 32.

  As described above, the changing unit 34 determines the capacitance value of the variable capacitance element 31 and the variable capacitance element so that the bias voltage Vb detected by the detection unit 90 matches the target value Vt according to the comparison result of the comparison unit 33. At least one of the 32 capacitance values is changed.

  Next, a method for manufacturing a semiconductor device using the plasma processing apparatus 1 according to the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a method for manufacturing a semiconductor device using the plasma processing apparatus 1.

  In step (placement step) S <b> 1, a substrate to be processed (for example, a semiconductor substrate) WF is placed on the electrode 10 in the processing chamber 50.

In step (generation step) S <b> 2, the power supply circuit 20 generates high frequency power and supplies the high frequency power to the electrode 10. At the same time, the plasma generator 80 generates plasma PL in a space 51 separated from the electrode 10 in the processing chamber 50. Specifically, the high frequency power supply 81 generates high frequency power and supplies it to the antenna coil 82. The antenna coil 82 generates an electromagnetic wave (a high frequency magnetic field) using the supplied high frequency power. The electromagnetic wave generated by the antenna coil 82 passes through the dielectric wall 83 and is introduced into the space 51 in the processing chamber 50. In the space 51 in the processing chamber 50, the processing gas is discharged to generate plasma PL, and ions (for example, F ⁺ , CF 3 ^+, etc.) are generated from the processing gas together with radicals.

  In step (detection step) S3, the detection unit 90 generates a bias voltage Vb, which is the difference between the potential Vpl of the plasma PL generated by the plasma generation unit 80 and the potential Ve of the electrode 10 supplied with power by the power supply circuit 20. To detect.

  Specifically, the detection unit 90 measures the potential of the detection terminal 92 and calculates a potential difference between the potential of the detection terminal 92 (that is, the potential of the electrode 10) and the side wall portion in the vicinity of the plasma PL (that is, the ground potential) in the processing container. Measured as bias voltage Vb. At this time, the potential difference between the plasma PL potential Vpl and the processing chamber wall is small and can be ignored.

Alternatively, as a more accurate method, the detection unit 90 detects the potential Vpl of the plasma PL via the detection terminal 91 and detects the potential Ve of the electrode 10 via the detection terminal 92. And the detection part 90 is
Vb = Vpl-Ve
Thus, the bias voltage Vb is obtained. The detector 90 supplies the bias voltage Vb thus detected to the power supply circuit 20.

  In step (comparison step) S <b> 4, the comparison unit 33 of the power supply circuit 20 receives a signal indicating the bias voltage Vb detected by the detection unit 90 from the detection unit 90. In addition, the target value Vt is set in the comparison unit 33 in advance. The comparison unit 33 compares the bias voltage Vb indicated by the signal received from the detection unit 90 with the target value Vt, and supplies the comparison result to the change unit 34. The changing unit 34 determines whether the bias voltage Vb detected by the detecting unit 90 matches the target value Vt according to the supplied comparison result. For example, if the difference between the bias voltage Vb and the target value Vt deviates from a predetermined allowable range, the changing unit 34 determines that the bias voltage Vb does not match the target value Vt, and sets the difference between the bias voltage Vb and the target value Vt. If the difference is within a predetermined allowable range, it is determined that the bias voltage Vb matches the target value Vt. If the bias voltage Vb does not match the target value Vt (No in step S4), the changing unit 34 proceeds to step S5, and if the bias voltage Vb matches the target value Vt (Yes in step S4). ), The process proceeds to step S6.

  In step (correction step) S5, the changing unit 34 of the power supply circuit 20 changes the variable capacitance element 31 so that the bias voltage Vb detected by the detecting unit 90 matches the target value Vt according to the supplied comparison result. And at least one of the capacitance value of the variable capacitance element 32 is changed.

  That is, the changing unit 34 performs at least an operation of increasing the capacitance value of the variable capacitance element 32 when the comparison result of the comparison unit 33 indicates that the bias voltage Vb indicated by the signal is higher than the target value Vt. As a result, the capacitance value of the variable capacitance element 32 connected in parallel with the generation unit 40 increases, and the capacitance value of the power supply circuit 20 increases so that the bias voltage Vb decreases. That is, the capacitance value of the power supply circuit 20 is corrected so that the bias voltage Vb approaches the target value Vt. Note that the changing unit 34 may further perform an operation of reducing the capacitance value of the variable capacitance element 31.

  When the comparison unit 33 indicates that the bias voltage Vb indicated by the signal is lower than the target value Vt, the changing unit 34 performs at least an operation of increasing the capacitance value of the variable capacitance element 31. As a result, the capacitance value of the variable capacitance element 31 connected in series with the generation unit 40 increases, so that the capacitance value of the power supply circuit 20 decreases so that the bias voltage Vb increases. That is, the capacitance value of the power supply circuit 20 is corrected so that the bias voltage Vb approaches the target value Vt. Note that the changing unit 34 may further perform an operation of reducing the capacitance value of the variable capacitance element 32.

  In this way, the processes in steps S3 to S5 are repeated until the bias voltage Vb matches the target value Vt. The impedance matching by the matching box 42 may be performed every time the correction process in step S5 is performed.

  In step (processing step) S6, the changing unit 34 supplies a signal indicating that the bias voltage Vb matches the target value Vt to a controller (not shown). In response to this, the controller switches the condition for the correction operation to the condition for the machining operation, and controls the plasma generator 80. Thereby, the plasma processing apparatus 1 processes (for example, etching process) the to-be-processed substrate WF in the state in which the bias voltage Vb detected by the detection unit 90 matches the target value Vt.

  Here, let us consider a case where steps S3 to S5 are not performed in the semiconductor device manufacturing method using the plasma processing apparatus 1. In this case, since the parasitic capacitance in the power supply circuit 20 varies between a plurality of different plasma processing apparatuses of the same model, the potential Vpl of the plasma PL generated by the plasma generator 80 and the electrode supplied with power by the power supply circuit 20 The bias voltage Vb, which is the difference from the ten potential Ve, also tends to vary between different plasma processing apparatuses. For example, FIG. 14 shows a result of evaluating a plurality of plasma processing apparatuses having different bias voltages Vb in a state where the processes of steps S3 to S5 are not performed after steps S1 and S2. FIG. 14 shows that the bias voltage Vb varies greatly between different plasma processing apparatuses.

  In contrast, in the first embodiment, steps S3 to S5 are repeatedly performed after steps S1 and S2. That is, the bias voltage Vb is detected (step S3), and when the detected bias voltage Vb does not match the target value Vt (No in step S4), the detected bias voltage Vb matches the target value Vt. The process of correcting the capacitance value of the power supply circuit 20 is repeated (step S5). As a result, when the detected bias voltage Vb matches the target value Vt (Yes in step S4), the plasma processing apparatus 1 determines that the bias voltage Vb detected by the detection unit 90 is between the different plasma processing apparatuses. The substrate WF to be processed is processed in a state where it matches the target value Vt (which is a common value) (step S6). As a result, it is possible to perform processing in a state where the bias voltage Vb is aligned with a common target value Vt between different plasma processing apparatuses, and therefore, variations in processing dimensions between different plasma processing apparatuses can be reduced.

  In particular, the correction unit 30 of the power supply circuit 20 includes a variable capacitance element 31 connected in series with the electrode 10 and the generation unit 40, and a variable capacitance element 32 connected in parallel with the generation unit 40 with respect to the electrode 10. Have Thereby, in step S5, the capacitance value of the power supply circuit 20 can be corrected so that the bias voltage Vb approaches the target value Vt regardless of whether the bias voltage Vb is higher or lower than the target value Vt.

  Alternatively, let us consider a case where the power supply circuit 20 does not include the correction unit 30. In this case, as described above, since the parasitic capacitance in the power supply circuit 20 varies between different plasma processing apparatuses, the bias voltage Vb also tends to vary between different plasma processing apparatuses.

  On the other hand, in the first embodiment, the power supply circuit 20 includes the correction unit 30. The correction unit 30 compensates the capacitance value of the generation unit 40 so that the bias voltage Vb detected by the detection unit 90 matches the target value Vt (which is a value common to different plasma processing apparatuses), and the power supply circuit The capacity value of 20 is corrected. Thereby, since the processing by the plasma processing apparatus 1 can be performed in a state where the bias voltage Vb matches the target value Vt, variation in processing dimensions between different plasma processing apparatuses can be reduced.

  Alternatively, suppose that the plasma processing apparatus 1 does not include the detection unit 90. In this case, since the correction unit 30 cannot grasp what value the bias voltage Vb is, it cannot perform correction so that the bias voltage Vb matches the target value Vt. This makes it difficult to reduce variations in processing dimensions between different plasma processing apparatuses.

  Alternatively, suppose that the plasma processing apparatus 1 does not include the detection unit 90 and includes a second detection unit that detects the capacitance value of the generation unit 40. In this case, since there are many parameters to be controlled in the plasma processing apparatus 1, there is a tendency that the correlation between the capacitance value of the generating unit 40 and the bias voltage Vb differs between plasma processing apparatuses. For this reason, the correction unit 30 cannot determine the value of the bias voltage Vb even if it receives the capacitance value of the generation unit 40 detected by the second detection unit, so that the bias voltage Vb is equal to the target value Vt. It is also impossible to make corrections so as to match. This makes it difficult to reduce variations in processing dimensions between different plasma processing apparatuses.

  On the other hand, in the first embodiment, the plasma processing apparatus 1 includes the detection unit 90. The detector 90 detects the bias voltage Vb. As a result, the correction unit 30 can grasp what value the bias voltage Vb has, and thus can correct the bias voltage Vb so as to match the target value Vt. As a result, variations in processing dimensions between different plasma processing apparatuses can be reduced.

  Alternatively, suppose that the plasma processing apparatus 1 does not include the detection unit 90 and the bias voltage Vb is detected by attaching a predetermined measuring tool to the plasma processing apparatus 1 during maintenance. In this case, unless the manufacture of the semiconductor device using the plasma processing apparatus 1 is temporarily suspended, the correction unit 30 cannot perform correction so that the bias voltage Vb matches the target value Vt. As a result, the throughput in the method of manufacturing a semiconductor device tends to decrease.

  On the other hand, in the first embodiment, the plasma processing apparatus 1 includes the detection unit 90. The detector 90 detects the bias voltage Vb. Thus, the correction unit 30 can correct the bias voltage Vb so as to match the target value Vt without interrupting the manufacturing of the semiconductor device using the plasma processing apparatus 1 (as in-line processing). As a result, it is possible to suppress a decrease in throughput in the semiconductor device manufacturing method.

  In the first embodiment, the case where the plasma processing apparatus 1 is an ICP (Inductive Coupling Plasma) type RIE apparatus has been described as an example, but the plasma processing apparatus 1 is not limited to an ICP type RIE apparatus. For example, the plasma processing apparatus 1 may be an ECR (Electron Cyclotron Resonance) type RIE apparatus or a parallel plate type RIE apparatus. When the plasma processing apparatus 1 is a parallel plate RIE apparatus, the plasma generation unit 80 replaces the antenna coil 82 and the dielectric wall 83 with an upper electrode disposed so as to face the electrode 10 in the processing chamber 50. Will have.

(Second Embodiment)
Next, the plasma processing apparatus 100 concerning 2nd Embodiment is demonstrated using FIG.4 and FIG.5. FIG. 4 is a diagram showing a schematic configuration of the plasma processing apparatus 100 according to the second embodiment. FIG. 5 is a diagram illustrating an internal configuration of the correction unit 130. Below, it demonstrates centering on a different point from 1st Embodiment.

  The plasma processing apparatus 100 includes a power supply circuit 120 and a controller 160. The controller 160 manages processing conditions used when controlling the plasma generator 80. The power supply circuit 120 includes a correction unit 130. The correction unit 130 receives a signal indicating processing conditions from the controller 160.

  Specifically, as illustrated in FIG. 5, the correction unit 130 includes a storage unit 136, a determination unit 137, and a comparison unit 133.

  The storage unit 136 stores a plurality of target values respectively associated with the machining conditions. The processing conditions include, for example, the type of processing gas to be supplied into the processing chamber 50 by the plasma generation unit 80. The storage unit 136 stores, for example, target value information as shown in FIG. The target value information has a processing gas column 1361 and a target value column 1362. The processing gas column 1361 stores information on the type of processing gas, for example, “processing gas A”, “processing gas B”,... The target value column 1362 stores information related to the target value, for example, “Vta”, “Vtb”,. By referring to this target value information, a target value corresponding to the type of processing gas can be specified. For example, by referring to the target value information, it can be specified that the target value corresponding to “processing gas A” is “Vta”, and the target value corresponding to “processing gas B” is “Vtb”. It can be identified. The target value information stored in the storage unit 136 is used in common when a plurality of plasma processing apparatuses 1 are operated under the same processing conditions, and the storage unit 136 itself can be shared between apparatuses. It is.

  The determination unit 137 receives a signal indicating the processing condition from the controller 160. In response to receiving the signal indicating the machining condition, the determining unit 137 refers to the target value information stored in the storage unit 136 and determines a target value corresponding to the processing condition indicated by the signal. The determination unit 137 supplies the determined target value to the comparison unit 133.

  The comparison unit 133 uses the target value supplied from the determination unit 137 with priority over the preset target value Vt. That is, the comparison unit 133 compares the bias voltage Vb detected by the detection unit 90 with the target value determined by the determination unit 137.

  Further, as shown in FIG. 7, the method for manufacturing a semiconductor device using the plasma processing apparatus 100 differs from the first embodiment in the following points.

  In step S11, the determination unit 137 determines whether or not the processing conditions by the plasma processing apparatus 100 have been changed. For example, the determination unit 137 holds a signal indicating the machining condition received from the controller 160, determines that the machining condition has been changed when receiving a signal indicating a different machining condition, and outputs a signal indicating the same machining condition. If it is received or if a signal indicating the machining condition is not received, it is determined that the machining condition is not changed. When the machining condition is changed (Yes in step S11), the determination unit 137 advances the process to step S12. When the machining condition is not changed (No in step S11), the determination unit 137 ends the process.

  In step (determination step) S12, the determination unit 137 refers to the target value information stored in the storage unit 136 and determines a target value corresponding to the processing condition indicated by the signal. The determination unit 137 supplies the determined target value to the comparison unit 133. The comparison unit 133 changes the target value used for comparison to the target value supplied from the determination unit 137.

  In step S5, the capacitance value of the variable capacitance element 31 and the variable capacitance are set so that the bias voltage Vb detected in step S3 matches the target value determined in step S12 according to the comparison result in step S4. At least one of the capacitance value of the element 32 is changed. In step S6, the controller 160 controls the plasma generator 80 under the managed processing conditions.

  Thus, in the second embodiment, the target value is changed for each processing condition (for example, the type of processing gas), so that the correction unit 130 matches the bias voltage Vb with the target value suitable for the processing condition. Correction can be performed as described above. As a result, it is possible to reduce variations in processing dimensions between different plasma processing apparatuses for each processing condition.

(Third embodiment)
Next, a plasma processing apparatus 200 according to the third embodiment will be described with reference to FIG. FIG. 8 is a diagram illustrating an internal configuration of the correction unit 230 in the plasma processing apparatus 200. Below, it demonstrates centering on a different point from 1st Embodiment.

  The correction unit 230 in the power supply circuit 220 in the plasma processing apparatus 200 includes a storage unit 236, a determination unit 237, and a timer 238.

  The storage unit 236 stores a plurality of target values respectively associated with the sections to which the elapsed time belongs. The elapsed time is, for example, the time that has elapsed since the last cleaning of the processing chamber 50 was performed. The storage unit 236 stores, for example, target value information as shown in FIG. The target value information has an elapsed time column 2361 and a target value column 2362. The elapsed time column 2361 stores information related to the section to which the elapsed time belongs, for example, “0 to T1”, “T1 to T2”,. The target value column 2362 stores information related to the target value, for example, “Vt1”, “Vt2”,. By referring to the target value information, the target value corresponding to the section to which the elapsed time belongs can be specified. For example, by referring to the target value information, it can be specified that the target value corresponding to “0 to T1” is “Vt1”, and the target value corresponding to “T1 to T2” is “Vt2”. It can be identified.

  The determination unit 237 receives a signal from the controller 160 indicating that the cleaning of the processing chamber 50 has been completed. The determination unit 137 activates the timer 238 in response to receiving a signal indicating that the cleaning of the processing chamber 50 has been completed. As a result, the timer 238 starts counting the elapsed time.

  Then, the determination unit 237 accesses the timer 238 and acquires elapsed time information from the timer 238. The determination unit 237 refers to the target value information stored in the storage unit 236 and determines a target value corresponding to the section to which the elapsed time belongs. The determination unit 237 supplies the determined target value to the comparison unit 133.

  Further, as shown in FIG. 10, the manufacturing method of the semiconductor device using the plasma processing apparatus 200 differs from the first embodiment in the following points.

  In step S21, the determination unit 237 determines whether or not the section to which the elapsed time belongs has been changed. For example, the determination unit 137 accesses the timer 238 and acquires elapsed time information from the timer 238. The determination unit 237 holds a signal indicating an elapsed time section corresponding to the target value used immediately before. When the elapsed time acquired from the timer 238 does not belong to the retained elapsed time section, the determining unit 237 determines that the section to which the elapsed time belongs has changed, and the elapsed time acquired from the timer 238 is retained. If it belongs to the elapsed time section, it is determined that the section to which the elapsed time belongs has not been changed. When the section to which the elapsed time belongs is changed (Yes in step S21), the determination unit 237 advances the process to step S22, and when the section to which the elapsed time belongs has not been changed (No in step S21), the determination unit 237 Proceed to S2.

  In step S <b> 22, the determination unit 237 refers to the target value information stored in the storage unit 236 and determines a target value corresponding to the section to which the elapsed time belongs. The determination unit 237 supplies the determined target value to the comparison unit 133. The comparison unit 133 changes the target value used for comparison to the target value supplied from the determination unit 237.

  In step S5, the capacitance value of the variable capacitance element 31 and the variable capacitance are set so that the bias voltage Vb detected in step S3 matches the target value determined in step S22 according to the comparison result in step S4. At least one of the capacitance value of the element 32 is changed.

  Thus, in the third embodiment, the target value is changed for each section to which the elapsed time belongs, so that the correction unit 230 matches the target value suitable for the section to which the elapsed time belongs. Correction can be performed. As a result, it is possible to reduce variations in processing dimensions between different plasma processing apparatuses while taking into account the change in state in the processing chamber 50 over time.

(Fourth embodiment)
Next, a plasma processing apparatus 300 according to the fourth embodiment will be described with reference to FIG. FIG. 11 is a diagram illustrating a schematic configuration of a plasma processing apparatus 300 according to the fourth embodiment. Below, it demonstrates centering on a different point from 1st Embodiment.

  The plasma processing apparatus 300 includes a storage unit 370 and a controller 360.

  The storage unit 370 stores correlation information related to the correlation between the bias voltage and the processing deviation amount. The processing deviation amount is, for example, the deviation amount of the actual processing dimension from the etching mask pattern. The storage unit 370 stores, for example, correlation information as illustrated in FIG. FIG. 12 shows the results of actual evaluation of the correlation between the bias voltage and the amount of processing deviation, and it can be seen that the bias voltage and the amount of processing deviation approximately have a correlation along a straight line indicated by a one-dot chain line. By referring to this correlation information, the amount of processing deviation corresponding to the current bias voltage can be predicted. For example, by referring to the correlation information, it can be estimated that the amount of processing deviation corresponding to the bias voltage Vb11 is L11.

  The controller 360 receives the bias voltage Vb detected by the detection unit 90 from the detection unit 90. The controller 360 refers to the correlation information stored in the storage unit 370 and predicts the amount of processing deviation corresponding to the bias voltage Vb detected by the detection unit 90. The controller 360 adjusts the machining conditions based on the predicted machining deviation amount so that the machining deviation amount falls within a predetermined threshold range. The machining conditions to be adjusted include, for example, machining time. When the predicted machining deviation amount exceeds the predetermined threshold range, the controller 360 shortens the machining time so that the machining deviation amount falls within the predetermined threshold range.

  Further, as shown in FIG. 13, a method for manufacturing a semiconductor device using the plasma processing apparatus 300 differs from the first embodiment in the following points.

  In step S31, the comparison unit 33 of the power supply circuit 20 compares the bias voltage Vb indicated by the signal received from the detection unit 90 with the target value Vt, and supplies the comparison result to the change unit 34. The changing unit 34 determines whether the bias voltage Vb detected by the detecting unit 90 matches the target value Vt according to the supplied comparison result. When the changing unit 34 does not match the bias voltage Vb with the target value Vt (No in step S31), the process proceeds to step S32. When the bias voltage Vb matches the target value Vt (Yes in step S31). ), The process proceeds to step S6.

  In step S32, the changing unit 34 of the power supply circuit 20 determines whether or not the number of times that the bias voltage Vb does not match the target value Vt is a predetermined number or more. Specifically, the changing unit 34 holds the count value of the number of times that the bias voltage Vb does not match the target value Vt, and counts up the count value of the number of times. Then, the changing unit 34 compares the count value after counting up with a predetermined number of times, and if the count value is equal to or larger than the predetermined number of times (Yes in Step S32), the process proceeds to Step S33, and the count value is less than the predetermined number of times. If yes (No in step S32), the process proceeds to step S5.

  In step S33, the changing unit 34 of the power supply circuit 20 supplies the controller 360 with a signal indicating that the number of times that the bias voltage Vb does not match the target value Vt is a predetermined number or more. The controller 360 receives the bias voltage Vb detected by the detection unit 90 from the detection unit 90 in response to receiving the signal. The controller 360 refers to the correlation information stored in the storage unit 370 and predicts the amount of processing deviation corresponding to the bias voltage Vb detected by the detection unit 90.

  In step S34, the controller 360 adjusts the machining conditions based on the predicted machining deviation amount so that the machining deviation amount falls within a predetermined threshold range. The machining conditions to be adjusted include, for example, machining time. When the predicted machining deviation amount exceeds the predetermined threshold range, the controller 360 shortens the machining time so that the machining deviation amount falls within the predetermined threshold range.

  As described above, in the fourth embodiment, even if the feedback operation including the detection operation of the bias voltage Vb by the detection unit 90 and the correction operation of the capacitance value of the power supply circuit 20 by the correction unit 30 is performed a predetermined number of times or more. When the voltage Vb does not match the target value Vt, a machining deviation amount corresponding to the detected bias voltage Vb is predicted, and the machining deviation amount falls within a predetermined allowable range based on the predicted machining deviation amount. Adjust the processing conditions. Thereby, even when the bias voltage Vb does not coincide with the target value Vt, it is possible to reduce variations in processing dimensions between different plasma processing apparatuses.

  1, 100, 200, 300 Plasma processing apparatus, 10 electrodes, 20, 120, 220 Power supply circuit, 30, 130, 230 Correction unit, 31, 32 Variable capacitance element, 31a, 31b, 32a, 32b Electrode, 33, 133 Comparison Part, 34 changing part, 35 variable capacity part, 40 generating part, 41 blocking capacitor, 42 matching box, 43 high frequency power supply, 50 processing chamber, 51 space, 80 plasma generating part, 81 high frequency power supply, 82 antenna coil, 83 dielectric Wall, 90 detection unit, 91, 92 detection terminal, 136, 236 storage unit, 137, 237 determination unit, 160, 360 controller, 238 timer, 370 storage unit, 1361 process gas column, 1362 target value column, 2361 elapsed time column 236 Target value field, PL plasma, WF target substrate.

Claims (6)

A method for manufacturing a semiconductor device using a plasma processing apparatus having an electrode disposed in a processing chamber and a power supply circuit for supplying power to the electrode,
A placing step of placing a semiconductor substrate on the electrode in the processing chamber;
Generating electric power from the power supply circuit to the electrode and generating plasma in a space separated from the electrode in the processing chamber;
A detection step of detecting a bias voltage which is a difference between the potential of the plasma generated in the generation step and the potential of the electrode to which power is supplied;
A correction step of correcting the capacitance value of the power supply circuit so that the bias voltage detected in the detection step matches a target value;
A processing step of processing the semiconductor substrate using the plasma processing apparatus in a state where the bias voltage detected in the detection step after the correction step is matched with the target value;
A method for manufacturing a semiconductor device, comprising: The power supply circuit is
A generator for generating electric power to be supplied to the electrode;
A correction unit that corrects the capacitance value of the power supply circuit by compensating the capacitance value of the generation unit so that the bias voltage detected by the detection unit matches a target value;
Have
The correction unit is
A first variable capacitance element connected in series to the electrode and the generator;
A second variable capacitance element connected in parallel to the generator with respect to the electrode;
Have
In the correction step, at least one of the capacitance value of the first variable capacitance element and the capacitance value of the second variable capacitance element is changed so that the bias voltage detected in the detection step matches a target value. The method of manufacturing a semiconductor device according to claim 1. A determination step of determining a target value corresponding to a processing condition by the plasma processing apparatus among a plurality of target values;
A comparison step of comparing the bias voltage detected in the detection step with the target value determined in the determination step;
Further comprising
In the correction step, the capacitance of the first variable capacitance element is set so that the bias voltage detected in the detection step matches the target value determined in the determination step according to the comparison result in the comparison step. 3. The method of manufacturing a semiconductor device according to claim 2, wherein at least one of a value and a capacitance value of the second variable capacitance element is changed. An electrode disposed in a processing chamber and on which a substrate to be processed is placed; a power supply circuit that supplies power to the electrode; a plasma generator that generates plasma in a space separated from the electrode in the processing chamber; Electric power is supplied to the electrode in the plasma processing apparatus including a detection unit that detects a bias voltage that is a difference between the potential of the plasma generated by the plasma generation unit and the potential of the electrode supplied with power by the power supply circuit. A power supply circuit for supplying,
A generator for generating electric power to be supplied to the electrode;
A correction unit that corrects the capacitance value of the power supply circuit by compensating the capacitance value of the generation unit so that the bias voltage detected by the detection unit matches a target value;
A power supply circuit comprising: An electrode disposed in the processing chamber and on which the substrate to be processed is placed;
A power supply circuit for supplying power to the electrode;
A plasma generator for generating plasma in a space separated from the electrode in the processing chamber;
A detection unit that detects a bias voltage that is a difference between a potential of the plasma generated by the plasma generation unit and a potential of the electrode supplied with power by the power supply circuit;
With
The power supply circuit is
A generator for generating electric power to be supplied to the electrode;
A correction unit that corrects the capacitance value of the power supply circuit by compensating the capacitance value of the generation unit so that the bias voltage detected by the detection unit matches a target value;
Have
The plasma processing apparatus processes the substrate to be processed in a state where a bias voltage detected by the detection unit matches the target value. The plasma processing apparatus is composed of a plurality of apparatuses, and the same target value is set when the same processing line is used between the apparatuses.
The plasma processing apparatus according to claim 5, wherein the correction unit corrects a bias voltage value for each apparatus so as to coincide with a target value.

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