TW201832286A - Plasma etching method - Google Patents

Abstract

In a plasma etching method, a deposit containing an element forming an upper electrode is deposited on a metal-containing mask having a predetermined pattern while sputtering the upper electrode by a plasma of a first processing gas. Then, an etching target film is etched by a plasma of a second processing gas while using the metal-containing mask on which the deposit is deposited as a mask.

Description

Plasma etching method

Each aspect and embodiment of the present invention relates to a plasma etching method and a plasma etching apparatus.

In the conventional technology, the plasma etching device uses, for example, a photoresist or a metal-containing mask as a mask to etch a film to be processed. In addition, if a photoresist is used as a mask, there is a method of applying a negative DC voltage to the upper electrode containing silicon, and simultaneously processing the plasma of the gas to deposit a silicon-containing deposit on the surface of the photoresist. As a protective film. [Habitual technical literature] [patent literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2003-282539 [Patent Document 2] Japanese Patent Laid-Open No. 2014-82228

[Problems to be Solved by the Invention] However, in the case where the plasma etching apparatus uses a metal-containing mask as a mask, no consideration is given to avoiding the stop of the etching caused by the mask material. That is, in the case of a plasma etching device using a metal-containing mask as a mask, metal is scattered from the metal-containing mask and adheres to the film to be treated as a metal compound, thereby hindering the film to be treated. Etching; as a result, there may be a problem that the etching stops. [Technical means to solve the problem]

The plasma etching method of one aspect of the present invention includes the following steps: a deposition step, while depositing an upper electrode with a plasma of a first processing gas, depositing a deposit containing elements constituting the upper electrode on a predetermined pattern A metal-containing mask; and an etching step, using the metal-containing mask containing a deposit containing elements constituting the upper electrode as a mask, and etching the film to be treated with a plasma of a second processing gas. [Effect of the invention]

By using the various layers and embodiments of the present invention and using a metal-containing mask as a mask, a plasma etching method can be realized, which can avoid the etching stop caused by the mask material.

The embodiments of the plasma etching method and the plasma etching apparatus disclosed below are described in detail with reference to the drawings. The invention disclosed in this embodiment is not limited. Each embodiment can be combined as appropriate within a range that does not contradict each other.

(Plasma Etching Apparatus of the First Embodiment) FIG. 1 is a cross-sectional view schematically showing a plasma etching apparatus according to the first embodiment. As shown in FIG. 1, the plasma etching device is a plasma etching device that applies a dual-frequency RF type at the lower portion. The plasma etching device includes a first high-frequency power source 89 and a carrier electrode 16 serving as a lower electrode. High-frequency (RF) power, and from the second high-frequency power source 90, for example, 2MHz high-frequency (RF) power is used to introduce ions; as shown in the figure, a variable DC power source 50 is connected to the upper part The electrode 34 is a plasma etching device that applies a predetermined direct current (DC) voltage to the upper electrode 34.

Fig. 2 is a schematic sectional view showing a plasma etching apparatus according to the first embodiment. The plasma etching apparatus is a parallel-plate plasma etching apparatus configured as a capacitive coupling type, and has, for example, a substantially cylindrical cavity (processing container) 10 made of anodized aluminum. The cavity 10 is grounded.

At the bottom of the cavity 10, a cylindrical support tray 14 is arranged through an insulating plate 12 made of ceramics or the like. On the support tray support table 14, a support tray 16 made of, for example, aluminum is provided. The carrier plate 16 constitutes a lower electrode, and a semiconductor wafer (hereinafter referred to as a “wafer”) W as a processing object is placed on the carrier plate 16.

On the top surface of the carrier plate 16, an electrostatic fixing base 18 for holding and holding the wafer W by electrostatic force is provided. The electrostatic fixing base 18 has a structure in which an electrode 20 made of a conductive film is sandwiched by a pair of insulating layers or sheets, and the electrode 20 is electrically connected to the DC power source 22. The electrostatic mount 18 is configured to attract and hold the wafer W by an electrostatic force such as a Coulomb force generated by a DC voltage from the DC power source 22.

A focus ring (correction ring) 24 is provided around the electrostatic mount 18 (wafer W) and on the top surface of the carrier plate 16 to improve the uniformity of etching. The focus ring (correction ring) 24 is formed of, for example, silicon. A cylindrical inner wall member 26 made of, for example, quartz is provided on the side surfaces of the supporting plate 16 and the supporting plate support 14.

A refrigerant chamber 28 is provided on the inside of the tray support table 14 on the circumference, for example. The refrigerant chamber 28 is provided with a refrigerant at a predetermined temperature from a quencher unit (not shown) provided on the outside through pipes 30a and 30b. The processing temperature of the wafer W on the carrier disk 16 is controlled by the temperature of the refrigerant.

In addition, a heat-conducting gas supply mechanism (not shown) supplies a heat-conducting gas such as helium gas between the top surface of the electrostatic mount 18 and the back surface of the wafer W through the gas supply line 32.

Above the carrier plate 16 as the lower electrode, an upper electrode 34 is provided in parallel so as to face the carrier plate 16. The space between the upper electrode 34 and the lower electrode 16 is the "plasma generating space". The upper electrode 34 faces the wafer W on the carrier plate 16 serving as the lower electrode, and forms a surface contacting the plasma generation space, that is, an opposite surface.

The upper electrode 34 is supported by the upper portion of the cavity 10 through the insulating shielding member 42. The upper electrode 34 is composed of an electrode plate 36 and an electrode support 38 of a water-cooled structure; the electrode plate 36 forms a surface opposite to the carrier plate 16 and has a plurality of gas release holes 37; the electrode support 38 is supported in a detachable manner The electrode plate 36 is made of a conductive material. The conductive material forming the electrode support 38 is, for example, aluminum whose surface is anodized. The electrode plate 36 is formed of a silicon-containing substance, for example, formed of silicon. An example of a silicon-based element constituting the upper electrode 34. A gas diffusion chamber 40 is provided inside the electrode support 38. A plurality of gas flow holes 41 communicating with the gas release holes 37 extend downward from the gas diffusion chamber 40.

A gas introduction port 62 is formed in the electrode support 38 for introducing a processing gas into the gas diffusion chamber 40. The gas introduction port 62 is connected to a gas supply pipe 64, and the gas supply pipe 64 is connected to a process gas supply source 66. A mass flow controller (MFC) 68 and an on-off valve 70 are sequentially provided on the gas supply pipe 64 from the upstream side. From the processing gas supply source 66, a fluorocarbon gas (CxFy) such as a C ₄ F ₈ gas is released as a processing gas for etching; it reaches the gas diffusion chamber 40 from the gas supply pipe 64 and passes through the gas passage. The flow holes 41 and the gas release holes 37 are released into the plasma generation space in a shower. That is, the upper electrode 34 functions as a shower head for supplying a process gas.

As described later, the processing gas supply source 66 supplies a processing gas for depositing a silicon-containing deposit, a processing gas for etching, and the like. Details of the gas supplied from the process gas supply source 66 will be described later.

The upper electrode 34 is electrically connected to the variable DC power source 50 through a low-pass filter (LPF) 46a. The variable DC power supply 50 may also be a bipolar power supply. The variable DC power supply 50 can be turned on or off by an on-off switch 52. The polarity, current, and voltage of the variable DC power supply 50 and the on / off of the on-off switch 52 are controlled by a controller (control device) 51.

The low-pass filter (LPF) 46a is used to capture high frequencies from the first and second high-frequency power sources described later, and is preferably composed of an LR filter or an LC filter.

The cylindrical ground conductor 10 a is provided so as to extend upward from the side wall of the cavity 10 to a position higher than the height of the upper electrode 34. The cylindrical ground conductor 10a has a top plate on the upper portion.

The carrier plate 16 as the lower electrode is electrically connected to the first high-frequency power source 89 via a matching device 87. In addition, the carrier disk 16 is electrically connected to the second high-frequency power source 90 via a matching device 88. The first high-frequency power source 89 outputs a frequency of 27 MHz or higher, for example, a high-frequency power of 40 MHz. The high-frequency power output by the first high-frequency power source 89 is high-frequency power used to generate plasma; hereinafter, it is briefly described as "generating high-frequency power for plasma". The second high-frequency power source 90 outputs a frequency of 13.56 MHz or less, for example, a high-frequency power of 2 MHz. The high-frequency power output from the second high-frequency power source 90 is high-frequency power used to introduce ions in the plasma; hereinafter, it is briefly described as "high-frequency power for introducing ions." In addition, the first high-frequency power source 89 may be electrically connected to the upper electrode 34 via the matching device 87.

The matchers 87 and 88 are used to match the load impedance of the internal (or output) impedances of the first and second high-frequency power sources 89 and 90, respectively. Their function is to generate a plasma in the cavity 10, The internal impedances of the first and second high-frequency power sources 89 and 90 and the load impedances are apparently matched.

An exhaust port 80 is provided at the bottom of the cavity 10, and the exhaust port 80 is connected to an exhaust device 84 via an exhaust pipe 82. The exhaust device 84 has a vacuum pump such as a turbo molecular pump, and can reduce the pressure in the cavity 10 to a desired degree of vacuum. Furthermore, a wafer W carrying-in / out port 85 is provided on a side wall of the cavity 10. The loading / unloading port 85 can be opened and closed by a gate valve 86. Furthermore, a deposition shield 11 is detachably provided along the inner wall of the cavity 10 to prevent the adhesion of by-products (deposits) from the etching. That is, the deposition shield 11 constitutes the cavity wall. Furthermore, the deposition shield 11 is also provided on the outer periphery of the inner wall member 26. An exhaust plate 83 is provided between the deposition shield 11 on the cavity wall side of the bottom of the cavity 10 and the deposition shield 11 on the inner wall member 26 side. In terms of the deposition shield 11 and the exhaust plate 83, it is preferable to use a ceramic material such as Y ₂ O ₃ coated with an aluminum material.

A DC grounded conductive member (grounding block) 91 is provided on a portion of the deposition shield 11 that constitutes the inner wall of the cavity 10 at a height approximately the same as that of the wafer W, thereby exerting it as described later. The effect of preventing abnormal discharge.

Each component of the plasma etching apparatus is configured to be connected to and controlled by a control unit (whole control device) 95. In addition, the control unit 95 is connected to a keyboard and a user interface 96; the keyboard is used by a process manager to perform input operations for managing a plasma etching device; the user interface 96 is composed of a display or the like, and Visual display of the operation status of the plasma processing device.

The control section 95 is connected to a memory section 97 storing a control program and a process recipe. The control program is used to implement various processes performed by the plasma etching device through the control of the control section 95. The process recipe is used to cooperate with the process. The program that causes each component of the plasma etching apparatus to execute processing under conditions. The process recipe can be recorded on a hard disk or semiconductor memory, or it can be stored in a portable computer such as CDROM, DVD and other readable memory media, and set at a predetermined position in the memory section 97.

In the plasma etching device, according to the instructions from the user interface 96, etc., as needed, any process recipe is called from the memory 97 to be executed by the control unit 95, and the plasma etching can be performed under the control of the control unit 95. The device performs the required processing.

For example, the control part 95 controls each part of a plasma etching apparatus so that it may perform the plasma etching method mentioned later. Here is a detailed example: while the control unit 95 sputters the upper electrode 34 with the plasma of the first processing gas, the deposit containing the elements constituting the upper electrode 34 is deposited on the "metal-containing shield" provided in the object to be processed. cover". Then, the control unit 95 etches the film to be processed with the “metal-containing mask on which the deposit containing the elements constituting the upper electrode 34 is deposited” as the mask, and the plasma is etched by the second processing gas. Here, the object to be processed is, for example, a wafer W.

When the plasma etching apparatus configured as described above performs an etching process, the gate valve 86 is first opened, and then the wafer W as an etching target is carried into the cavity 10 through the carrying-in and carrying-out port 85, and placed on a carrier tray. 16 on. Then, a processing gas for etching is supplied from the processing gas supply source 66 to the gas diffusion chamber 40 at a predetermined flow rate; on the one hand, it is supplied into the cavity 10 through the gas flow hole 41 and the gas release hole 37. On the other hand, the air is exhausted from the inside of the cavity 10 by the exhaust device 84 so that the pressure inside the cavity 10 reaches a setting value within a range of, for example, 0.1 to 150 Pa.

With the etching gas introduced into the cavity 10 in this manner, a predetermined power is applied from the first high-frequency power source 89 to the carrier plate 16 serving as the lower electrode to generate the plasma high-frequency power while maintaining the predetermined power High-frequency power for ion introduction is applied from the second high-frequency power source 90. Then, a predetermined DC voltage is applied from the variable DC power source 50 to the upper electrode 34. Furthermore, a DC voltage is applied from the DC power source 22 for the electrostatic mount 18 to the electrodes 20 of the electrostatic mount 18 to fix the wafer W to the carrier 16.

The processing gas released from the gas release hole 37 formed in the electrode plate 36 of the upper electrode 34 is generated by a high-frequency power generated in a glow discharge between the upper electrode 34 and the carrier plate 16 as the lower electrode. The slurry is etched, and the processed surface of the wafer W is etched with the free radicals and ions generated by the plasma.

In the plasma etching apparatus, since the carrier plate 16 as the lower electrode is supplied with high-frequency power in a higher frequency range (for example, above 27 MHz) by the first high-frequency power source 89, the plasma can be made in a better state. High density; even under lower voltage conditions, high density plasma can be formed.

(Plasma Etching Method of First Embodiment) FIG. 3 is a flowchart showing an example of a plasma etching process flow of the first embodiment. As described in detail below, the plasma etching apparatus executes a series of processes on a wafer W in which a "processed film" and a "metal-containing mask having a predetermined pattern" are sequentially stacked. In the following description, the upper electrode 34 is formed of a silicon-containing substance.

The film to be processed is, for example, a silicon-containing film. The silicon-containing film contains, for example, at least any one of SiO ₂ , SiOC, SiC, and SiN. Furthermore, the metal-containing mask is, for example, a metal, a metal nitride, a metal oxide, a metal carbide, or a compound of a metal and silicon. The metal includes, for example, at least any one of titanium (Ti), tantalum (Ta), and tungsten (W). The metal nitride includes, for example, at least any one of titanium nitride (Ti ₃ N ₄ ) and tantalum nitride (Ta ₃ N ₅ ). The metal oxide is, for example, titanium oxide (TiO ₂ ). The metal carbide is, for example, tungsten carbide (WC). Compounds of metals and silicon, for example, tungsten disilicon (WSi ₂ ).

Returning to the description of FIG. 3. As shown in FIG. 3, when the plasma etching device reaches the processing timing (procedure S101), it applies a negative DC voltage to the silicon-containing upper electrode 34 while using a plasma of the first processing gas to shield the metal containing mask. On the surface, a silicon-containing deposit is deposited to perform a deposition step (procedure S102). The first processing gas contains a rare gas. The noble gas contains, for example, at least one of argon, helium, xenon, and neon. The silicon-containing deposit is an example of a deposit containing elements constituting the upper electrode 34.

FIG. 4 is a view showing a deposition step in the first embodiment. The control unit 95 of the plasma etching apparatus applies the high-frequency power to the first high-frequency power source 89 and connects the upper electrode 34 to the variable DC power source 50 to apply a predetermined direct current (DC) voltage. At this time, high-frequency power for ion introduction is not applied from the second high-frequency power source 90. That is, as shown in (1) of FIG. 4, when forming the plasma, the control unit 95 applies a predetermined negative DC voltage to the upper electrode 34 from the variable DC power source 50. More preferably, the plasma etching device applies a voltage from the variable DC power source 50 to the surface of the upper electrode 34 that is the application electrode, that is, the surface of the electrode plate 36, so that the self-bias voltage Vdc on the surface of the electrode plate 36 is deepened ( That is, the absolute value of Vdc on the surface of the upper electrode 34 is increased to such an extent that a predetermined (moderate) sputtering effect can be obtained. The control unit 95 supplies a first processing gas, such as argon, into the cavity 10.

As a result, as shown in FIG. 4 (1), for example, argon ions can bombard the surface of the electrode plate 36, and the silicon forming the electrode plate 36 is sputtered, and the sputtered silicon falls to the metal-containing mask. 203. As a result, as shown in FIG. 4 (2), a silicon-containing deposit 204 is deposited on the surface of the metal-containing mask 203. Thereby, since the plasma-resistant property of the metal-containing mask 203 is improved, the scattering of the metal from the metal-containing mask 203 is suppressed, and the etching of the treated film is not hindered by the metal compound. As a result, the stop of the etching caused by the material containing the metal mask 203 can be avoided.

Returning to the description of FIG. 3. Next, the plasma etching apparatus uses a metal-containing mask on which a silicon-containing deposit is deposited as a mask, and uses the plasma of the second processing gas to etch the processed film to perform an etching step (procedure S103). The second processing gas includes, for example, a CF-based gas. The CF-based gas includes, for example, at least one of a C ₄ F ₆ gas, a C ₅ F ₈ gas, a C ₄ F ₈ gas, a CF ₄ gas, a CHF ₃ gas, and a CH ₂ F ₂ gas.

(Effects of the First Embodiment) In the first embodiment described above, while applying a negative DC voltage to the upper electrode 34, a silicon-containing deposit is deposited on the substrate to be processed by the plasma of the first processing gas. The metal-containing mask of the body is used as a mask, and the film to be processed is etched by the plasma of the second processing gas. Thereby, since the plasma-resistant property of the metal-containing mask is improved, the scattering of the metal from the metal-containing mask is suppressed, and the etching of the treated film is not hindered by the metal compound. As a result, the stop of the etching caused by the metal mask-containing material can be avoided.

(Another Embodiment) Although the plasma etching method and the plasma etching apparatus according to the first embodiment have been described above, the technology to be disclosed is not limited to this. Hereinafter, another embodiment will be described.

In the above embodiment, a case where a silicon-containing deposit is deposited on a metal-containing mask by applying a negative DC voltage to the upper electrode 34 is taken as an example, but the technology to be disclosed is not limited thereto. For example, instead of applying a negative DC voltage to the upper electrode 34, high-frequency power below 13.56 MHz may be applied to the upper electrode 34, for example, 2 MHz. Alternatively, high-frequency power below 13.56 MHz may be applied to the lower electrode 16, for example, 2 MHz. Alternatively, both the upper electrode 34 and the lower electrode 16 may be applied with high-frequency power below 13.56 MHz, for example, 2 MHz. By applying the high-frequency power in the above frequency range to both the upper electrode 34, the lower electrode 16, or both the upper electrode 34 and the lower electrode 16, the same sputtering effect as when a negative DC voltage is applied to the upper electrode 34 can be obtained. As a result, silicon-containing deposits are deposited on the metal-containing mask.

Furthermore, in the above embodiment, the case where the upper electrode 34 is formed of a silicon-containing substance is described as an example, but the technology to be disclosed is not limited to this. For example, the upper electrode 34 may be formed of a substance containing a metal. The metal-containing substance includes, for example, ruthenium as the metal. Metals such as ruthenium are examples of elements constituting the upper electrode 34. When the upper electrode 34 is formed of a metal-containing substance, the control unit 95 applies a negative DC voltage to the upper electrode 34, and deposits a metal-containing substance for the metal-containing mask.

When the upper electrode 34 is formed of a silicon-containing material or a metal-containing material, the following phenomena are considered to occur. That is, a region that is combined with the "atoms constituting the metal-containing mask" and the landing "atoms constituting the upper electrode 34" forms an interface between the metal-containing mask and the deposit deposited on the metal-containing mask. ; With this, the plasma-resistant properties of the metal-containing mask will be improved. For example, in a case where the upper electrode 34 containing silicon is used, a metal-containing mask and a region containing a metal silicide are formed at the interface between the deposits deposited on the metal-containing mask.

(Repeat of the deposition step and the etching step) The plasma etching device can also alternate the deposition step and the etching step. By alternating the deposition step and the etching step, the plasma-resistant characteristics of the metal-containing mask will be further improved, so the metal scattering from the metal-containing mask will be more reliably suppressed, and the etching of the treated film will not be affected by the metal. Obstacles to compounds. As a result, it is possible to more reliably avoid the stop of etching due to the material containing the metal mask.

Furthermore, in the case where the plasma etching apparatus alternates the repeated deposition step and the etching step, the etching step is performed with a longer processing time than the deposition step. With this, even in the deposition step, not only the metal-containing mask, but also the silicon-containing deposit having a larger thickness is deposited on the film to be processed, and the film to be processed can be efficiently removed together in the etching step. And silicon-containing deposits on the treated film.

(Processing time of the deposition step) In another embodiment, as the number of iterations of the deposition step and the etching step is repeated, the deeper the predetermined pattern of the film to be processed, the plasma etching device can also increase the processing time of the deposition step. The predetermined pattern of the film to be treated includes holes or grooves. Hereinafter, referring to FIG. 5, a further description will be given for a case where the processing time is increased in the deposition step.

FIG. 5 is a diagram illustrating an example of a cross section of a wafer W after each step is performed in the case of an overlying deposition step and an etching step. Here, a case where the deposition step and the etching step are repeated three times is taken as an example for description. In addition, the plasma etching apparatus executes a series of processes on a wafer W in which a film to be processed 301 and a metal mask 302 having a predetermined pattern are sequentially laminated.

First, a plasma etching apparatus performs a first deposition step. The cross section of the wafer W after the first deposition step is performed is, for example, in a state shown in FIG. 5 (a-1). That is, by performing the first deposition step, a silicon-containing deposit 303a is deposited on the surface of the metal-containing mask 302.

Next, the plasma etching apparatus performs a first etching step. The cross section of the wafer W after the first etching step is performed is, for example, a state shown in FIG. 5 (b-1). That is, by performing the first etching step, a predetermined pattern 304 is formed on the film 301 to be processed.

Next, the plasma etching apparatus performs a second deposition step. The processing performed by the plasma etching apparatus is the processing time of the second deposition step, which is longer than that of the first deposition step. The cross section of the wafer W after the second deposition step is performed will be, for example, a state shown in (a-2) of FIG. 5. That is, the processing time of the second deposition step is made longer than that of the first deposition step, and the surface of the metal-containing mask 302 is deposited more than silicon-containing deposits. 303a Thicker silicon-containing deposits 303b.

Next, the plasma etching apparatus performs a second etching step. The cross section of the wafer W after the second etching step is performed is, for example, a state shown in FIG. 5 (b-2). That is, by performing the second etching step, the predetermined pattern 304 formed on the film 301 to be processed becomes deeper.

Next, the plasma etching apparatus performs a third deposition step. At this time, the processing performed by the plasma etching apparatus is such that the processing time of the third deposition step is longer than that of the second deposition step. The cross section of the wafer W after the third deposition step is performed will be, for example, a state shown in FIG. 5 (a-3). That is, the processing time of the third deposition step is made longer than that of the second deposition step, and the surface of the metal-containing mask 302 is deposited more than silicon-containing deposits 303b Thicker silicon-containing deposits 303c.

Next, the plasma etching apparatus performs a third etching step. The cross section of the wafer W after the third etching step is performed is, for example, a state shown in (b-3) of FIG. 5. That is, by performing the third etching step, the predetermined pattern 304 formed on the film 301 to be processed becomes deeper.

Like this, as the number of iterations of the deposition step and the etching step makes the holes or grooves formed in the film to be processed deeper, the processing time of the deposition step is lengthened, thereby forming on the metal-containing mask Very thick silicon-containing deposits. As a result, since the plasma-resistant characteristics of the metal-containing mask with respect to the film to be processed are improved, it is possible to more reliably prevent the etching stop caused by the material of the metal-containing mask. Furthermore, the deeper the predetermined pattern formed on the film to be processed, the smaller the amount of silicon-containing deposits that can reach the bottom of the predetermined pattern. Therefore, even if the processing time of the deposition step is lengthened, the predetermined pattern can be prevented from coming off. Decrease in release property.

(In the deposition step, a negative DC voltage is applied to the upper electrode.) In another embodiment, as the predetermined number of iterations of the deposition step and the etching step is made deeper, the plasma etching device can also be used. The absolute value of the negative DC voltage applied to the upper electrode 34 in the deposition step is increased more. In this case, the ion energy that bombards the upper electrode 34 will increase, so that the amount of silicon splashed out of the upper electrode 34 will increase, and the amount of silicon splashed out on the surface of the metal-containing mask will increase. . Thereby, the silicon deposit on the metal-containing mask can be gradually thickened. As a result, since the plasma-resistant characteristics of the metal-containing mask with respect to the film to be processed are improved, it is possible to more reliably avoid stopping the etching due to the material of the metal-containing mask.

(Pressure in the deposition step) In another embodiment, as the predetermined pattern formed on the film to be processed is deeper with the number of iterations of the deposition step and the etching step, the plasma etching apparatus may increase the pressure in the deposition step. . In this case, compared with the case where the pressure is not changed, the ion flux bombarded to the upper electrode 34 will increase, the amount of silicon splashed out of the upper electrode 34 will increase, and the sputtered silicon will fall to The amount of metal mask surface will increase. As a result, the silicon deposits on the metal-containing mask can be thickened. As a result, since the plasma-resistant characteristic of the metal-containing mask with respect to the film to be processed is improved, it is possible to more reliably avoid the stop of etching due to the material of the metal-containing mask.

(High-frequency power for introducing ions in the etching step) In another embodiment, as the number of iterations of the deposition step and the etching step makes the predetermined pattern formed on the film to be processed deeper, the plasma etching device can also be increased. High frequency power for introducing ions in the etching step. An example of adding high-frequency power for ion introduction in the etching step will be described below with reference to FIG. 6.

FIG. 6 is a diagram illustrating another example of a wafer W cross-section after each step is performed in the case of the repeated deposition step and the etching step. Here, a case where the deposition step and the etching step are repeated three times is taken as an example for description. In addition, the plasma etching apparatus executes a series of processes on a wafer W in which a film to be processed 301 and a metal mask 302 having a predetermined pattern are sequentially laminated.

First, a plasma etching apparatus performs a first deposition step. The cross section of the wafer W after the first deposition step is performed is, for example, in a state shown in (a-1) of FIG. 6. That is, by performing the first deposition step, a silicon-containing deposit 303a is deposited on the surface of the metal-containing mask 302.

Next, the plasma etching apparatus performs a first etching step. The cross-section of the wafer W after the first etching step is performed is, for example, a state shown in FIG. 6 (b-1). That is, by performing the first etching step, a predetermined pattern 304 is formed on the film 301 to be processed.

Next, the plasma etching apparatus performs a second deposition step. The processing performed by the plasma etching apparatus is the processing time of the second deposition step, which is longer than that of the first deposition step. The cross-section of the wafer W after the second deposition step is performed is, for example, a state shown in (a-2) of FIG. 6. That is, the processing time of the second deposition step is made longer than that of the first deposition step, and the surface of the metal-containing mask 302 is deposited more than silicon-containing deposits. 303a Thicker silicon-containing deposits 303b.

Next, the plasma etching apparatus performs a second etching step. At this time, compared with the high-frequency power for introducing ions in the first etching step, the plasma etching apparatus increases the high-frequency power for introducing ions in the second etching step. The cross section of the wafer W after the second etching step is performed is, for example, a state shown in FIG. 6 (b-2). That is, by performing the second etching step, the predetermined pattern 304 formed on the film 301 to be processed becomes deeper. Furthermore, by increasing the high-frequency power for introducing ions in the second etching step, the energy of ions incident on the predetermined pattern 304 is increased. As a result, the linearity of the ions incident on the predetermined pattern 304 is improved.

Next, the plasma etching apparatus performs a third deposition step. At this time, the processing performed by the plasma etching apparatus is such that the processing time of the third deposition step is longer than that of the second deposition step. The cross section of the wafer W after the third deposition step is performed will be, for example, a state shown in (a-3) of FIG. 6. That is, the processing time of the third deposition step is made longer than that of the second deposition step, and the surface of the metal-containing mask 302 is deposited more than silicon-containing deposits 303b Thicker silicon-containing deposits 303c.

Next, the plasma etching apparatus performs a third etching step. At this time, compared with the high-frequency power for introducing ions in the second etching step, the plasma etching apparatus increases the high-frequency power for introducing ions in the third etching step. The cross section of the wafer W after the third etching step is performed will be, for example, a state shown in FIG. 6 (b-3). That is, by performing the third etching step, the predetermined pattern 304 of the film 301 to be processed becomes deeper. Furthermore, by increasing the high-frequency power for introducing ions in the third etching step, the energy of ions incident on the predetermined pattern 304 is further increased. As a result, the linearity of the ions incident on the predetermined pattern 304 is improved.

As such, if the predetermined pattern formed on the film to be processed is deeper, the high-frequency power for introducing ions in the etching step is increased, thereby improving the straightness of ions incident on the predetermined pattern. At this time, since the thickness of the silicon-containing deposits on the metal-containing mask has been increased, the plasma-resistant characteristics of the metal-containing mask relative to the film to be treated can be reduced without deteriorating the impact on the predetermined pattern. Obliquely incident ions on the sidewall. As a result, while suppressing the scattering of metal from a metal-containing mask, it is possible to suppress the shape of a predetermined pattern from becoming a bow shape of a wine barrel or bending of the shape of a predetermined pattern on the way. ).

(Frequency of high-frequency power for introducing ions in the etching step) In another embodiment, the plasma etching device can also be used as the predetermined pattern formed on the film to be processed becomes deeper with the number of iterations of the deposition step and the etching step. The lower the frequency of the high-frequency power for introducing ions in the etching step. In this case, the energy of ions incident on a predetermined pattern formed on the film to be processed increases. As a result, the linearity of ions incident on a predetermined pattern is improved. At this time, since the thickness of the silicon-containing deposits on the metal-containing mask has been increased, the plasma-resistant characteristics of the metal-containing mask relative to the film to be treated can be reduced without deteriorating the impact on the predetermined pattern. Obliquely incident ions on the sidewall. As a result, while suppressing the scattering of the metal from the metal-containing mask, it is also possible to suppress the occurrence of buckling in which the shape of the predetermined pattern becomes a bow-shaped bend of the wine barrel shape, or the shape of the predetermined pattern is deformed on the way.

(Pressure in the etching step) In another embodiment, as the number of iterations of the deposition step and the etching step is repeated, the deeper the predetermined pattern of the film to be processed, the plasma etching device can also reduce the pressure in the etching step. As a result, the linearity of ions incident on a predetermined pattern is improved. At this time, since the thickness of the silicon-containing deposits on the metal-containing mask has been increased, the plasma-resistant characteristics of the metal-containing mask relative to the film to be treated can be reduced without deteriorating the impact on the predetermined pattern. Obliquely incident ions on the sidewall. As a result, similar to the case of increasing the high-frequency power for introducing ions in the etching step, it is possible to suppress the scattering of the metal from the metal-containing mask while suppressing the shape of the predetermined pattern to become a bow-shaped bend of the barrel shape, or It is the occurrence of bending that deforms the shape of a given pattern on the way.

(Oxidation step) In another embodiment, the plasma etching device may further perform the following oxidation step between the deposition step and the etching step: the silicon-containing deposit deposited on the metal-containing mask, The plasma of the oxygen-containing gas is oxidized to form an oxidized region. In this case, the plasma etching apparatus removes the oxidized area while etching the film to be processed by the plasma of the second processing gas in the etching step. The oxygen-containing gas includes, for example, at least any one of O ₂ , CO ₂ and CO. Hereinafter, a case where the oxidation step is performed between the deposition step and the etching step will be further described with reference to FIG. 7.

FIG. 7 is a diagram showing an example of a cross-section of a wafer W after each step is performed when an oxidation step is performed between a deposition step and an etching step. Here, the plasma etching apparatus executes a series of processes on a wafer W in which a film to be processed 401 and a metal-containing mask 402 having a predetermined pattern are sequentially stacked. In addition, the to-be-processed film 401 is set as a thing with the predetermined pattern 404 formed.

First, a plasma etching apparatus performs a deposition step. The cross section of the wafer W after the deposition step is performed is, for example, a state shown in FIG. 7 (a). That is, by performing a deposition step, a silicon-containing deposit 403 is deposited on the surface of the metal-containing mask 402. In addition, a part of the silicon-containing deposit 403 is attached to the opening of the pattern of the metal-containing mask 402. Here, if the portion of the silicon-containing deposit 403 attached to the opening portion of the pattern containing the metal mask 402 is thick, the opening portion of the pattern containing the metal mask 402 may be blocked.

Next, the plasma etching apparatus uses an O ₂ plasma to perform the oxidation step. The cross section of the wafer W after the oxidation step is performed will be, for example, a state shown in FIG. 7 (b). That is, the surface of the silicon-containing deposit 403 is oxidized to form an oxidized region 403a.

Next, the plasma etching apparatus performs an etching step. The cross-section of the wafer W after the etching step is performed is, for example, a state shown in FIG. 7 (c). That is, by performing the etching step, the predetermined pattern of the film 401 to be processed is deeper, and the oxidized region 403 a is removed from the silicon-containing deposit 403. As a result, the portion of the silicon-containing deposit 403 attached to the opening portion of the pattern of the metal-containing mask 402 becomes thin.

Like this, by oxidizing the surface of the silicon-containing deposit on the metal-containing mask to form an oxidized region, and removing the oxidized region when etching the film to be processed, the silicon-containing deposit can be attached to the metal-containing mask. A portion of the opening portion of the pattern of the cover becomes thinner. As a result, the blocking of the opening portion of the pattern including the metal mask can be suppressed.

(Repeat of Deposition Step, Oxidation Step, and Etching Step) In another embodiment, the plasma etching apparatus may sequentially repeat the deposition step, the oxidation step, and the etching step. In this case, a portion of the silicon-containing deposit that adheres to the opening portion of the pattern containing the metal mask is thinned, and the plasma-resistant property of the metal-containing mask is improved while being etched. As a result, it is possible to more stably meet the occlusion of the openings of the pattern containing the metal mask, and to more reliably avoid stopping the etching due to the material containing the metal mask.

(Processing Time in the Oxidation Step) In another embodiment, as the predetermined number of iterations of the deposition film, the oxidation step, and the etching step is made deeper, the plasma etching device can be lengthened. Treatment time in the oxidation step. In this case, the oxidized area can be thickened in stages in accordance with the thickness of the silicon-containing deposit on the metal-containing mask, and the oxidized area can be appropriately removed when the film to be processed is etched. As a result, even in the case where the deposition step, the oxidation step, and the etching step are sequentially repeated, the blocking of the opening portion of the pattern including the metal mask can be suppressed.

(Pressure in the oxidation step) In another embodiment, as the deposition pattern, the oxidation step, and the etching step are repeated, the deeper the predetermined pattern formed on the film to be processed, the more the plasma etching device can increase the oxidation. The pressure in the steps. In this case, the oxidized area can be thickened in stages in accordance with the thickness of the silicon-containing deposit on the metal-containing mask, and the oxidized area can be appropriately removed when etching the film to be processed. As a result, even in the case where the deposition step, the oxidation step, and the etching step are sequentially repeated, the blocking of the opening portion of the pattern including the metal mask can be suppressed.

(High-frequency power for plasma generation in the oxidation step) In another embodiment, as the predetermined number of iterations of the deposition step, the oxidation step, and the etching step makes the predetermined pattern formed on the film to be processed deeper, the plasma etching is performed. The device can also increase the high-frequency power for plasma generation in the oxidation step. In this case, the oxidized area can be thickened in stages in accordance with the thickness of the silicon-containing deposit on the metal-containing mask, and the oxidized area can be appropriately removed when the film to be processed is etched. As a result, even in the case where the deposition step, the oxidation step, and the etching step are sequentially repeated, the blocking of the opening portion of the pattern including the metal mask can be suppressed.

Hereinafter, the disclosed plasma etching method will be described in more detail with examples. However, the disclosed plasma etching method is not limited to the following embodiments.

(Comparative Example 1) In Comparative Example 1, an etching step was performed on the object to be processed. The object to be processed was a test wafer having the following structure. The etching step is performed using the following conditions. (Processed object) Processed film: SiO ₂ film with metal mask: Titanium nitride (Ti ₃ N ₄ ) (etching step) Process gas: C ₄ F ₆ / Ar / O ₂ = 5/950 / 4sccm Pressure: 2.7Pa (20mTorr) High-frequency power from the first high-frequency power supply: 100W High-frequency power from the second high-frequency power supply: 150W DC voltage supplied to the upper electrode: -300V Processing time: 600 seconds

(Example 1) In Example 1, for the object to be processed, a deposition step for depositing a silicon-containing deposit was performed before an etching step was performed; and an alternating iterative deposition step and an etching step were performed 50 times. As the system to be treated, a structure having the same structure as that of Comparative Example 1 was used. The deposition step was performed under the following conditions. The etching step was performed under the same conditions as in Comparative Example 1 except that the processing time shown below was used. (Deposition step) Process gas: Ar = 800sccm Pressure: 6.7Pa (50mTorr) High-frequency power from the first high-frequency power supply: 300W High-frequency power from the second high-frequency power supply: 0W DC voltage to the upper electrode:- 900V processing time: 5 seconds (etching step) processing time: 10 seconds

FIG. 8 is a diagram showing the processing results of Comparative Example 1 and Example 1. FIG. In FIG. 8, “Conv. Etch 600 seconds” represents the object after the etching step in Comparative Example 1. In addition, "Si coat + Conv. Etch 5 seconds + 10 seconds, 50 cycles" represents the object after 50 times of the alternating iterative deposition step and the etching step in Example 1. The “cross section” in the figure is a traced drawing of a photograph obtained by enlarging the cross section of the object to be processed.

Furthermore, in FIG. 8, “SiO 2 Depth” represents the depth of the etched holes formed in the SiO ₂ film.

As shown in FIG. 8, in Comparative Example 1, the etching stoppage due to the metal-containing mask occurred. On the other hand, in Example 1, the depth of the etching hole is "293 nm", which satisfies a preset allowable specification.

As can be seen from the comparison between Example 1 and Comparative Example 1, in Example 1, it is possible to avoid the stop of the etching caused by the material containing the metal mask by depositing a silicon-containing deposit.

In the case where a plurality of objects to be processed are continuously processed, it is conceivable that the sputtered atoms are accumulated on the inner wall of the cavity 10 due to the sputtering of the upper electrode 34. Therefore, it is also possible to perform a cleaning process to remove the adhered matter on the inner wall of the cavity 10 every time one piece or one batch of objects to be processed is processed.

10‧‧‧ Cavity

10a‧‧‧ ground conductor

11‧‧‧ Deposition shield

12‧‧‧ Insulation board

14‧‧‧ Carrier tray support desk

16‧‧‧carriage tray

18‧‧‧ Electrostatic Mount

20‧‧‧ electrode

22‧‧‧DC Power

24‧‧‧Focus Ring

26‧‧‧Inner wall members

28‧‧‧Refrigerant Room

30a, 30b‧‧‧Piping

32‧‧‧Gas supply line

34‧‧‧upper electrode

36‧‧‧electrode plate

37‧‧‧gas release hole

38‧‧‧ electrode support

40‧‧‧Gas diffusion chamber

41‧‧‧gas vent hole

42‧‧‧ Insulating shielding member

46a‧‧‧Low-pass filter

50‧‧‧ Variable DC Power Supply

51‧‧‧controller

52‧‧‧on-off switch

62‧‧‧Gas inlet

64‧‧‧Gas supply pipe

66‧‧‧Processing gas supply source

68‧‧‧mass flow controller

70‧‧‧ On-off valve

80‧‧‧ exhaust port

82‧‧‧Exhaust pipe

83‧‧‧Exhaust plate

84‧‧‧Exhaust device

85‧‧‧ moved in and out

86‧‧‧Gate Valve

87‧‧‧ Matcher

88‧‧‧ Matcher

89‧‧‧The first high-frequency power supply

90‧‧‧ 2nd high frequency power supply

91‧‧‧ conductive member

95‧‧‧Control Department

96‧‧‧user interface

97‧‧‧Memory Department

203‧‧‧ with metal mask

204‧‧‧ Silicon-containing deposits

301‧‧‧treated film

302‧‧‧ with metal mask

303a‧‧‧ silicon-containing deposits

303b‧‧‧ Silicon-containing sediment

303c‧‧‧ Silicon-containing deposits

304‧‧‧ established pattern

401‧‧‧ treated film

402‧‧‧ with metal mask

403‧‧‧ silicon-containing deposits

403a‧‧‧oxidized area

404‧‧‧Predetermined pattern

W‧‧‧ Wafer

S101 ～ S103‧‧‧Procedure

[FIG. 1] FIG. 1 is a cross-sectional view schematically showing a plasma etching apparatus according to the first embodiment. [Fig. 2] Fig. 2 is a schematic sectional view showing a plasma etching apparatus according to the first embodiment. [Fig. 3] Fig. 3 is a flowchart showing an example of a plasma etching process flow of the first embodiment. [Fig. 4] Fig. 4 is a diagram showing a deposition step in the first embodiment. [Fig. 5] Fig. 5 is a diagram showing an example of a cross section of a wafer W after each step is performed in the case of a repeated deposition step and an etching step. [FIG. 6] FIG. 6 is a diagram illustrating another example of a wafer W section after each step is performed in the case of the repeated deposition step and the etching step. [FIG. 7] FIG. 7 is a diagram illustrating an example of a cross-section of a wafer W after each step is performed when an oxidation step is performed between a deposition step and an etching step. [Fig. 8] Fig. 8 is a diagram showing the processing results of Comparative Example 1 and Example 1. [Fig.

Claims (19)

A plasma etching method includes the following steps: a deposition step, while depositing an upper electrode with a plasma of a first process gas, depositing a deposit containing elements constituting the upper electrode on a metal-containing mask having a predetermined pattern; A mask; and an etching step, using the metal-containing mask on which "the deposit containing the elements constituting the upper electrode" is deposited as a mask, and etching the film to be treated with a plasma of a second processing gas. For example, the plasma etching method of item 1 of the patent application scope, wherein the deposition step is performed by applying a negative DC voltage to the upper electrode, or by applying high-frequency power below 13.56 MHz to the upper electrode, or by applying The lower electrode applies high-frequency power below 13.56 MHz, and a deposit containing elements constituting the upper electrode is deposited on the metal-containing mask. For example, the plasma etching method according to item 1 or 2 of the application, wherein the deposition step and the etching step are performed alternately and repeatedly. For example, the plasma etching method according to item 3 of the application, wherein the deeper the predetermined pattern formed on the film to be processed with the number of iterations of the deposition step and the etching step, the processing time in the deposition step is deeper. Longer. For example, the plasma etching method according to item 3 of the patent application, wherein as the deposition step and the number of iterations of the etching step are repeated, the deeper the predetermined pattern formed on the film to be processed is applied to the deposition step in the The absolute value of the negative DC voltage of the upper electrode increases. For example, the plasma etching method according to item 3 of the patent application, wherein the deeper the predetermined pattern formed on the film to be processed with the number of iterations of the deposition step and the etching step, the greater the pressure in the deposition step. Increase. For example, the plasma etching method according to item 3 of the patent application, wherein the deeper the predetermined pattern formed on the film to be processed with the number of iterations of the deposition step and the etching step is used to introduce the etching step. The higher the high-frequency power of the ions in the plasma, the greater the power. For example, the plasma etching method according to item 3 of the patent application, wherein the deeper the predetermined pattern formed on the film to be processed with the number of iterations of the deposition step and the etching step is used to introduce the etching step. The lower the frequency of the high-frequency power of the ions in the plasma. For example, the plasma etching method according to item 3 of the application, wherein the deeper the predetermined pattern formed on the film to be processed with the number of iterations of the deposition step and the etching step, the greater the pressure in the etching step. reduce. For example, the plasma etching method according to item 1 or 2 of the patent application scope, wherein between the deposition step and the etching step, the method further includes the following steps: an oxidation step to deposit the surface of the deposit on the metal-containing mask And oxidizing the plasma with an oxygen-containing gas to form an oxidized region; the etching step removes the oxidized region while etching the film to be processed by the plasma of the second processing gas. For example, the plasma etching method according to item 10 of the application, wherein the deposition step, the oxidation step, and the etching step are sequentially performed repeatedly. For example, the plasma etching method according to item 11 of the application, wherein as the deposition step, the oxidation step, and the number of iterations of the etching step make the predetermined pattern formed on the film to be processed deeper, the oxidation is performed. The longer the processing time in the step. For example, the plasma etching method according to item 11 of the application, wherein as the deposition step, the oxidation step, and the number of iterations of the etching step make the predetermined pattern formed on the film to be processed deeper, the oxidation is performed. The pressure in the step increases. For example, the plasma etching method according to item 11 of the application, wherein as the deposition step, the oxidation step, and the number of iterations of the etching step make the predetermined pattern formed on the film to be processed deeper, the oxidation is performed. The higher the high-frequency power used to generate the plasma in the step. For example, the plasma etching method of item 1 or 2 of the patent application scope, wherein the metal-containing mask is a metal, a metal nitride, a metal oxide, a metal carbide, or a metal and silicon compound. For example, the plasma etching method according to item 15 of the application, wherein the metal contains at least any one of titanium (Ti), tantalum (Ta), and tungsten (W). For example, the plasma etching method of item 1 or 2 of the patent application scope, wherein the film to be processed is a silicon-containing film. For example, the plasma etching method according to item 1 or 2 of the patent application scope, wherein the first processing gas includes a rare gas. For example, the plasma etching method according to item 1 or 2 of the patent application scope, wherein the second processing gas includes a CF-based gas.