JPWO2011001779A1 - Manufacturing method of silicon structure, manufacturing apparatus thereof, and manufacturing program thereof - Google Patents

Abstract

One method of manufacturing a silicon structure according to the present invention includes a first step of converting a first iodine fluoride into an etching gas by applying a first high-frequency power, and the above-described first high-frequency power. By alternately repeating the second step of converting the second iodine fluoride into plasma using the second high-frequency power by applying a low second high-frequency power, the silicon region in the object to be processed including the silicon region And a step of etching. As a result, a silicon structure having a good sidewall shape with high perpendicularity can be obtained by anisotropic dry etching of silicon with reduced influence on global warming.

Description

  The present invention relates to a method of manufacturing a silicon structure, a manufacturing apparatus thereof, and a manufacturing program thereof.

  The technical field to which MEMS (Micro Electro Mechanical Systems) devices using silicon are applied is steadily expanding, and in recent years, the technology has been applied not only to micro turbines and sensors but also to information communication field and medical field. Yes. One of the main elemental technologies that support this MEMS technology is anisotropic dry etching of silicon, and it can be said that the development of this elemental technology supports the development of MEMS technology.

Conventionally, among several existing anisotropic dry etching processes for silicon, a typical process proposed by a plurality of companies including the applicant of the present application is an etching process and a protective film forming process that are repeatedly performed. Process (for example, Patent Document 1). In the etching process of this process, sulfur hexafluoride (SF ₆ ) has been mainly used as an etching gas. Further, in the protective film forming step of this process, carbon fluoride (especially C ₄ F ₈ ) that forms an organic deposition film has been used as the protective film forming gas.

JP 2002-239014 A

In recent years, the technology of anisotropic dry etching of silicon has progressed dramatically, but on the other hand, the influence of greenhouse gases that have been used in the industry to carry out the process has begun to be concerned. . For example, fluorocarbons represented by the above-mentioned sulfur hexafluoride (SF ₆ ) and C ₄ F ₈ have a very high so-called global warming potential (GWP). It is an urgent task to think about the global environment. However, since sulfur hexafluoride (SF ₆ ) and fluorocarbon have been used as the main gas that supports anisotropic dry etching technology for silicon, it is not easy to find an alternative gas that can withstand market demands. Absent.

The present invention is directed to the development of anisotropic dry etching technology for silicon that achieves high verticality and good sidewall shape by using a gas with a low global warming potential instead of sulfur hexafluoride (SF ₆ ) or fluorocarbon. It contributes greatly.

We, sulfur hexafluoride (SF ₆₎ and Upon selecting the alternative gas fluorocarbon, silicon by etching characteristics and fluorinated plasma of carbon of silicon by plasma of sulfur hexafluoride (SF ₆₎ Investigation and analysis of the characteristics of the protective film formed on the top were conducted. In addition, the inventors have conducted extensive research on a number of alternative gas candidates, particularly focusing on the anisotropy of the silicon structure and the shape of the sidewalls, which directly affect the performance of various devices. As a result, the inventors repeatedly perform the etching process and the protective film forming process described above even when a gas having a global warming potential (GWP) that is almost negligible is a single gas depending on conditions. We found that it can be applied to the process.

Specifically, although the detailed mechanism has not yet been clarified, when the above-described gas is employed, the object to be processed (for example, a silicon substrate) is set by setting the power applied in the plasma to a specific range. It was confirmed that some deposits were likely to be formed on the surface. Accordingly, the inventors actively utilize the above-described change in the form of the deposit due to the difference in applied power, thereby protecting not only sulfur hexafluoride (SF ₆ ) but also a high global warming potential (GWP). It has been found that anisotropic etching of silicon can be performed without using a fluorocarbon gas for film formation. The present invention was created from the above viewpoint.

  One method of manufacturing a silicon structure according to the present invention includes a first step of converting a first iodine fluoride into an etching gas by applying a first high-frequency power, and the above-described first high-frequency power. By alternately and repeatedly performing a second step of converting the second iodine fluoride into a plasma using a protective film forming gas by applying a low second high frequency power, the silicon region in the object to be processed including the silicon region An etching step.

According to this silicon structure manufacturing method, not only the first iodine fluoride is used in place of sulfur hexafluoride (SF ₆ ) but also C ₄ F ₈ that has been used as a protective film forming gas in the past. A representative fluorocarbon gas is also not used. As a result, the etching process in which the first iodine fluoride is turned into plasma and the protective film forming process in which the second iodine fluoride is turned into plasma are alternately repeated, thereby achieving high verticality and good sidewall shape. A silicon structure having

  In another silicon structure manufacturing method of the present invention, the first high-frequency power is applied to an induction coil (hereinafter also simply referred to as a coil) using a dielectric coupled plasma etching apparatus. A first step of converting iodine fluoride into a plasma using an etching gas, and applying a second high-frequency power lower than the first high-frequency power to the induction coil to thereby convert the second iodine fluoride into a protective film forming gas And alternately performing the second step of converting to plasma as described above, and applying high frequency power to the stage electrode on which the object to be processed including the silicon region is placed during the first step described above, An etching step.

According to this silicon structure manufacturing method, not only the first iodine fluoride is used in place of sulfur hexafluoride (SF ₆ ) but also C ₄ F ₈ that has been used as a protective film forming gas in the past. A representative fluorocarbon gas is also not used. As a result, an etching process in which the first iodine fluoride is turned into plasma by a dielectric coupled plasma etching apparatus and a protective film forming process in which the second iodine fluoride is turned into plasma by the apparatus are repeatedly performed alternately. As a result, a silicon structure having high verticality and good sidewall shape can be obtained.

  Also, the manufacturing program of one silicon structure of the present invention includes a first step of converting the first iodine fluoride into plasma by applying the first high-frequency power, and the first high-frequency power described above. By alternately performing a second step of converting the second iodine fluoride into a plasma as a protective film forming gas by applying a lower second high frequency power, the silicon in the workpiece including the silicon region is obtained. Etching the region.

According to this silicon structure manufacturing program, not only the first iodine fluoride is used in place of sulfur hexafluoride (SF ₆ ) but also C ₄ F ₈ that has been used as a protective film forming gas. A representative fluorocarbon gas is also not used. As a result, the etching step in which the first iodine fluoride is turned into plasma and the protective film forming step in which the second iodine fluoride is turned into plasma are alternately repeated, thereby achieving high verticality and good sidewall shape. A silicon structure having

  In addition, another silicon structure manufacturing program of the present invention uses a dielectric coupled plasma etching apparatus to apply a first high-frequency power to an induction coil, thereby converting the first iodine fluoride into an etching gas into a plasma. And a second step of applying a second high-frequency power lower than the first high-frequency power to the induction coil to convert the second iodine fluoride into a plasma as a protective film forming gas. During the first step, the silicon region is etched by applying high-frequency power to the stage electrode on which the workpiece including the silicon region is placed.

According to this silicon structure manufacturing program, not only the first iodine fluoride is used in place of sulfur hexafluoride (SF ₆ ) but also C ₄ F ₈ that has been used as a protective film forming gas. A representative fluorocarbon gas is also not used. As a result, an etching step in which the first iodine fluoride is turned into plasma by the dielectric coupling type plasma etching apparatus and a protective film forming step in which the second iodine fluoride is turned into plasma by the apparatus are alternately repeated. As a result, a silicon structure having high verticality and good sidewall shape can be obtained.

  In addition, a silicon structure manufacturing apparatus according to the present invention includes a control unit that is controlled by any one of the silicon structure manufacturing programs described above or a recording medium that records any one of the silicon structure manufacturing programs. ing.

According to the manufacturing method, the manufacturing apparatus, or the manufacturing program of the present invention, the etching process in which the first iodine fluoride is turned into plasma and the protective film forming process in which the second iodine fluoride is turned into plasma are alternately repeated. By doing so, a silicon structure having high verticality and good sidewall shape can be obtained. In addition, iodine fluoride is almost negligible compared to sulfur hexafluoride (SF ₆ ) and fluorocarbon gas (typically C ₄ F ₈ ), which have a high global warming potential (GWP). Since it is gas (substantially GWP is 0 (zero)), it can greatly contribute to the suppression of global warming.

It is sectional drawing which shows the structure of the manufacturing apparatus of the silicon structure in one embodiment of this invention. It is a schematic diagram which shows a part of final silicon structure in one embodiment of this invention. Is a graph showing a temporal change in the flow rate of iodine pentafluoride (IF ₅₎ Gas in iodine pentafluoride (IF ₅₎ gas flow rate and the etching step in the protective film formation step in one embodiment of the present invention. It is a figure which shows the time change of the induction coil application electric power in the protective film formation process in one Embodiment of this invention, and the induction coil application electric power in an etching process. It is a figure which shows the time change of the applied electric power to the stage electrode in the protective film formation process in one Embodiment of this invention, and the applied electric power to the stage electrode in an etching process. It is a figure which shows the time change of the chamber internal pressure in the protective film formation process in one Embodiment of this invention, and the chamber internal pressure in an etching process. It is a manufacture flowchart of a silicon structure in one embodiment of the present invention.

DESCRIPTION OF SYMBOLS 10 Silicon structure 12 Etching mask 14 Side wall 20 Chamber 21 Stage 22a, 22b Gas cylinder 23a, 23b Gas flow regulator 24 Inductive coil 25 1st high frequency power supply 26 2nd high frequency power supply 27 Vacuum pump 28 Exhaust flow volume regulator 29 Control part 60 Computer 100 Silicon structure manufacturing equipment

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings unless otherwise specified. In the drawings, the elements of the present embodiment are not necessarily shown to scale. Moreover, in order to make each drawing easy to see, some reference numerals may be omitted. Unless otherwise specified, the flow rates of the following various gases indicate the flow rates in the standard state.

  FIG. 1 is a cross-sectional view showing an example of a device configuration of a silicon structure manufacturing apparatus 100 (hereinafter also simply referred to as a manufacturing apparatus 100) according to the present embodiment. FIG. 2 is a schematic view showing a part of the final silicon structure of the present embodiment. In the present embodiment, the silicon substrate W that is an object to be processed is a single crystal silicon substrate, but is not limited to this. For example, the present embodiment can be applied even to a polycrystalline silicon substrate or an amorphous silicon substrate. Similarly, the present embodiment can be applied to an object to be processed (for example, a substrate) having a polycrystalline silicon layer or an amorphous silicon layer in part.

  First, the configuration of the silicon structure manufacturing apparatus 100 shown in FIG. 1 will be described. A silicon substrate W to be etched (hereinafter also simply referred to as a substrate W) is placed on a stage 21 provided on the lower side of the chamber 20. In the chamber 20, at least one gas selected from a first iodine fluoride gas that is an etching gas and a second iodine fluoride gas that is a protective film forming gas is supplied from each cylinder 22a and 22b, respectively. It is supplied through the regulators 23a and 23b. These gases are turned into plasma by the induction coil 24 to which high frequency power is applied by the first high frequency power source 25. Thereafter, high-frequency power is applied to the stage 21 using the second high-frequency power source 26, so that the generated plasma is drawn into the silicon substrate W. Here, in the present embodiment, the power is applied to the stage 21 in a pulse form, in other words, in a state where the ON state and the OFF state of the application repeatedly appear at predetermined intervals. Further, a vacuum pump 27 is connected to the chamber 20 via an exhaust flow rate regulator 28 in order to decompress the inside of the chamber 20 and exhaust a gas generated after the process. Note that the exhaust flow rate from the chamber 20 is changed by an exhaust flow rate regulator 28. The above-described gas flow rate regulators 23a and 23b, the first high frequency power source 25, the second high frequency power source 26 capable of applying pulses, and the exhaust flow rate regulator 28 are controlled by a control unit 29. A known pressure gauge for measuring the pressure in the chamber 20 is not shown.

  Next, the manufacturing process of the silicon structure 10 of this embodiment will be described. Note that the final silicon structure 10 of this embodiment has a trench structure having a width of about 50 μm and a depth of about 25 μm.

Figure 3A is a diagram showing a time change of the flow rate of the embodiment of iodine pentafluoride in the protective film forming step pentafluoride in (IF ₅₎ gas flow rate and the etching step (IF ₅₎ gas. Moreover, FIG. 3B is a figure which shows the time change of the induction coil application electric power in the protective film formation process of this embodiment, and the induction coil application electric power in an etching process. FIG. 3C is a diagram showing temporal changes in power applied to the stage electrode (also referred to as substrate applied power) in the protective film forming step of the present embodiment and power applied to the stage electrode in the etching step. In addition, FIG. 3D is a diagram illustrating a change over time in the chamber internal pressure in the protective film forming step and the chamber internal pressure in the etching step of the present embodiment. In order to make it easy to distinguish between the protective film forming step and the etching step in each figure, “D” representing the protective film forming step period and “E” representing the etching step period are shown. 3A to 3D show only a part of the time zone of the repeated protective film forming process or etching process.

Here, the anisotropic dry etching of silicon according to the present embodiment includes a protective film forming step in which a second iodine fluoride gas that is a protective film forming gas is introduced, and a first iodine fluoride gas that is an etching gas. A method of sequentially repeating the introduced etching process is adopted. The protective film forming gas that is the first iodine fluoride gas and the etching gas that is the second iodine fluoride gas in this embodiment are both iodine pentafluoride (IF ₅ ). In the present embodiment, a silicon substrate W on which a resist film is patterned as the etching mask 12 using a known photolithography technique is used.

  In the manufacturing process of the silicon structure 10 of this embodiment, first, in the protective film forming process, the protective film forming gas is 200 sccm (also referred to as 200 mL / min.) For 2 seconds which is one unit processing time. The pressure in the chamber 20 is controlled to 8 Pa. Although high frequency power of 13.56 MHz is applied to the induction coil 24 by 600 W (second high frequency power), no power is applied to the stage 21. On the other hand, in the subsequent etching process, the etching gas is supplied at 200 sccm for 9 seconds, which is a unit processing time, and the pressure in the chamber 20 is controlled to 15 Pa. A high frequency power of 13.56 MHz (first high frequency power) is applied to the induction coil 24, and a high frequency power of 13.56 MHz is 80 W to the stage 21 (a third high frequency power may be used for convenience). Applied. As shown in FIGS. 3A to 3D, the above-described protective film forming step and etching step are continuously repeated for a predetermined time (about 10 minutes in the present embodiment), whereby the silicon structure 10 shown in FIG. Is formed.

  Note that the etching rate under the anisotropic dry etching condition of this embodiment is about 2.5 μm / min. (Micrometers / minute).

As described above, in this embodiment, iodine pentafluoride (IF ₅ ) that is so small that the global warming potential (GWP) is almost negligible is used in the protective film forming step and the etching step. Therefore, as described above, the total amount of greenhouse gases discharged for forming the silicon structure 10 having the trench structure shown in FIG. 2 is significantly suppressed.

Although the detailed mechanism has not yet been clarified, when the above-described iodine pentafluoride (IF ₅ ) is adopted, the power to be applied to the induction coil 24 is set to a specific range, thereby to-be-processed object (for example, silicon substrate) The inventors' investigation confirmed that some deposits were formed on the surface of W). That is, by actively utilizing the above-described change in the form of the deposit due to the difference in applied power, as described above, even when only iodine pentafluoride (IF ₅ ) gas is used, the protective film It is possible to create both a formation process and an etching process. Specifically, the applied power to the induction coil 24 in the protective film forming process is set lower than the applied power to the induction coil 24 in the etching process.

Here, when the iodine pentafluoride (IF ₅ ) gas is turned into a plasma in the etching step, a preferable coil applied power is 1000 W or more and 5000 W or less. If the coil applied power is less than 1000 W, the etching is hindered by the above-described deposits, so that there is a high possibility that a residue will form on the bottom surface of the etched structure such as a trench. On the other hand, when the coil applied power exceeds 5000 W, the manufacturing cost of the silicon structure increases including the cost required for the etching apparatus. Further, iodine pentafluoride case of plasma in the protective film forming step (IF ₅₎ Gas, preferably coil applied power is less than 300 W 1000W. If this coil applied power is less than 300 W, there is an increased possibility that plasma conversion of iodine pentafluoride (IF ₅ ) gas will not be achieved. On the other hand, when the coil applied power is 1000 W or more, it contributes to the etching of silicon rather than the formation of deposits. As a result of the analysis by the inventors, it is considered that at this stage, any of the above-mentioned deposits may be any substance containing I (iodine).

  Incidentally, the control unit 29 provided in the above-described manufacturing apparatus 100 is connected to the computer 60. The computer 60 monitors or comprehensively controls the above process by a manufacturing program of the silicon structure 10 for executing the above anisotropic dry etching process. Hereinafter, a manufacturing program for the silicon structure 10 will be described with reference to a specific manufacturing flowchart. In this embodiment, the above-described manufacturing program is stored in a known recording medium such as an optical disk inserted into a hard disk drive in the computer 60 or an optical disk drive provided in the computer 60. The storage destination of is not limited to this. The manufacturing program can also monitor or control each of the processes described above via a known technique such as a local area network or an Internet line.

  FIG. 4 is a manufacturing flowchart of the silicon structure 10 of the present embodiment.

  As shown in FIG. 4, when the manufacturing program for the silicon structure 10 of this embodiment is executed, first, in step S101, after the silicon substrate W is transferred into the chamber 20, the gas in the chamber 20 is exhausted. The Thereafter, in steps S102 to S104, anisotropic dry etching is performed on the silicon substrate W in the chamber 20 under the above-described conditions.

  Specifically, first, in step S102, a step of performing the protective film forming process of the present embodiment is executed. Next, a step of performing the etching process of the present embodiment is executed (step S103).

  Thereafter, as shown in step S104, the program according to the present embodiment has the number of times that the respective steps of the step of performing the protective film forming step (step S102) and the step of performing the etching step (step S103) were initially set. It is determined whether or not it has been repeatedly executed. As a result, when the initially set number of times is repeatedly executed, the program of the present embodiment stops the anisotropic dry etching (step S105). On the other hand, when the initially set number of times is not repeatedly executed, a step of performing the protective film forming step and the etching step again is executed (steps S102 and S103).

  After the anisotropic dry etching is stopped, the program of the present embodiment is brought into a state where the silicon substrate W is taken out as shown in Step S105 (Step S106), and then the program of the present embodiment is terminated. At this time, the substrate W may be directly taken out from the chamber after the chamber 20 is restored to the atmospheric pressure, but the substrate W is connected via a loader / unloader (not shown) device that can be connected to the chamber 20. May be removed.

  As described above, the manufacturing program for the silicon structure 10 according to the present embodiment integrally controls each condition in the etching process and the protective film forming process. As a result of executing the manufacturing program according to the present embodiment, a silicon structure having a high sidewall and a good sidewall shape is formed.

In the above-described embodiment, iodine pentafluoride (IF ₅ ) is used for both the etching gas (first iodine fluoride gas) and the protective film forming gas (second iodine fluoride gas). However, the present invention is not limited to this. Instead of iodine pentafluoride (IF ₅ ), iodine trifluoride (IF ₃ ) and iodine heptafluoride (IF ₇ ) can also be applied to the above-described embodiments. Further, the etching gas and the protective film forming gas need not be the same gas. For example, even if the etching gas is iodine pentafluoride (IF ₅ ) and the protective film forming gas is iodine trifluoride (IF ₃ ), at least some of the effects of the above-described embodiment are achieved. In addition, an etching gas in which a plurality of types of iodine fluoride gas is mixed and a protective film forming gas in which a plurality of types of iodine fluoride gas are mixed can also be employed. However, from the viewpoint of ease of process management or exhaust gas management, the etching gas and the protective film forming gas are preferably the same.

  In the above-described embodiment, the object to be etched is a trench, but is not limited to this. Even if the object is a hole, substantially the same effect as the present invention can be obtained. Furthermore, in the above-described embodiment, the opening width is one type (50 μm), but the present invention is not limited to this. Even if there are two or more opening widths, the present invention can be applied.

  In the above-described embodiment, the protective film forming step is first performed, and then the etching step is performed. However, the order is not limited. For example, even if an etching process is performed first and then a protective film formation process is performed, the same effects as those of the above-described embodiment are obtained. However, by performing the protective film formation step first, the protective film is deposited on the etching mask before being exposed to the plasma of the etching gas, which can contribute to improvement of the mask selectivity. Further, the process immediately before stopping the anisotropic etching of the present embodiment is not limited to the etching process. Even if the protective film forming step is executed immediately before the anisotropic etching is stopped, the same effect as that of the present embodiment can be obtained. That is, based on the flowchart shown in FIG. 4, the program in which anisotropic etching is stopped (step S105) after step S102 is executed as a final process after steps S102 and S103 are repeated is also implemented. It can be applied as one variant of form.

  In the above-described embodiment, high-frequency power is applied to the stage electrode only in the etching process, but the present invention is not limited to this. For example, in addition to the etching process, high-frequency power can be applied to the stage electrode also in the protective film forming process. Since high-frequency power is applied in the protective film forming step, formation of the protective film on the bottom surface of the etched region may be suppressed, which may rather contribute to an improvement in the etching rate.

  Furthermore, although ICP (Inductively Coupled Plasma) is used as the plasma generation means in the above-described embodiment, the present invention is not limited to this. The same effect as that of the above-described embodiment can be obtained even when other high-density plasma, for example, CCP (Capacitive-Coupled Plasma) or ECR (Electron-Cyclotron Resonance Plasma) is used. As described above, modifications that exist within the scope of the present invention are also included in the claims.

Claims (11)

A first step of converting the first high-frequency power into plasma using the first iodine fluoride as an etching gas; and a second step of applying a second high-frequency power lower than the first high-frequency power. A method of manufacturing a silicon structure, comprising: a step of etching the silicon region of an object to be processed including a silicon region by alternately and repeatedly performing a second step of converting it into plasma using iodine fluoride as a protective film forming gas. Applying a first high-frequency power to the induction coil using a inductively coupled plasma etching apparatus to form a plasma using a first iodine fluoride as an etching gas; and applying the first high-frequency power to the induction coil And applying a second high-frequency power lower than the second step of converting the second iodine fluoride into plasma using the protective film-forming gas alternately and including a silicon region during the first step. A method for manufacturing a silicon structure, comprising: a step of etching the silicon region by applying high-frequency power to a stage electrode on which a workpiece is placed. The method for manufacturing a silicon structure according to claim 1, wherein the first iodine fluoride and the second iodine fluoride are iodine pentafluoride (IF ₅ ). 3. The method for manufacturing a silicon structure according to claim 1, wherein the first high-frequency power is 1000 W or more and 5000 W or less, and the second high-frequency power is 300 W or more and less than 1000 W. 4. A first step of converting the first high-frequency power into plasma using the first iodine fluoride as an etching gas; and a second step of applying a second high-frequency power lower than the first high-frequency power. A silicon structure manufacturing program comprising: a step of etching the silicon region of an object to be processed including a silicon region by alternately and repeatedly performing a second step of converting to plasma using iodine fluoride as a protective film forming gas. Applying a first high-frequency power to the induction coil using a inductively coupled plasma etching apparatus to form a plasma using a first iodine fluoride as an etching gas; and applying the first high-frequency power to the induction coil And applying a second high-frequency power lower than the second step of converting the second iodine fluoride into plasma using the protective film forming gas, and alternately including a silicon region during the first step. A program for manufacturing a silicon structure, comprising: a step of etching the silicon region by applying high-frequency power to a stage electrode on which an object to be processed is placed. The manufacturing program for a silicon structure according to claim 5 or 6, wherein the first iodine fluoride and the second iodine fluoride are iodine pentafluoride (IF ₅ ). 7. The silicon structure manufacturing program according to claim 5, wherein the first high-frequency power is 1000 W or more and 5000 W or less, and the second high-frequency power is 300 W or more and less than 1000 W. 8.   The recording medium which recorded the manufacturing program of Claim 5 or Claim 6. A silicon structure manufacturing apparatus comprising a control unit controlled by the manufacturing program according to claim 5. An apparatus for manufacturing a silicon structure, comprising a control unit controlled by the recording medium according to claim 9.

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