JP5048611B2 - Semiconductor device manufacturing apparatus and semiconductor device manufacturing method - Google Patents

Description

  The present invention relates to a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method, and more particularly to a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method for manufacturing a semiconductor device by processing an indium compound semiconductor by dry etching. It is.

In optical integrated devices such as semiconductor lasers that are optical active elements and optical waveguides that are optical passive elements, Group 3-5 compound semiconductors are widely used to achieve higher functionality and higher performance. In the manufacturing process, a dry etching technique for forming concave lines and holes on the surface of the compound semiconductor is used. As plasma sources used for dry etching technology, capacitively coupled plasma, inductively coupled plasma, microwave-excited surface wave plasma, electron cyclotron mirror surface plasma, and the like are known. Since the plasma density and the incident energy of ions to the workpiece can be controlled independently, the machining shape can be made more accurate and finer than the wet etching technique. In particular, the inductively coupled plasma is widely used in the processing technology of the compound semiconductor because it can achieve both high etching speed and low damage (for example, Patent Documents 1 to 4). ).
JP 2006-005317 A JP 2005-150404 A JP 2004-080662 A JP 2004-063658 A

By the way, in the above-described dry etching technology for integrated optical devices, a selection ratio which is generally a ratio between an etching rate of a compound semiconductor and an etching rate of a mask material is used to further increase the accuracy and density of an optical functional element. Improvement is demanded. In the plurality of integrated optical devices optical functional element integrated into a mono Rishi click, the each light function element composition and film thickness of the compound semiconductor layer different are common, stack of these different compositions In the case where is an object to be processed, it is also required to reduce the etching rate difference between the layers in the laminate.

  For example, in the manufacturing process of a mesa optical waveguide, a compound semiconductor film for forming a core layer is formed on the surface of a substrate to be a grad layer, and the above-described dry etching technique is applied to this compound semiconductor film. Thus, the core layer is patterned. At this time, if the selection ratio between the compound semiconductor film to be the core layer and the mask pattern is low, even the mask pattern is etched during the etching of the compound semiconductor film and is covered with the mask pattern. It becomes difficult to obtain the desired shape of the core layer, for example, etching proceeds to the core layer. In addition, when the etching rate in the depth direction is not uniform in the core layer that is a laminate, the flatness on the side wall of the core layer is impaired, which is significant for high accuracy and high density of the optical waveguide. It becomes an obstacle.

As a technique for suppressing such a problem, there is a method of simply increasing the thickness of the etching mask, but in order to pattern a thick mask material, it is necessary to form a thick resist film for forming the mask pattern. Such thickening of the resist film makes it difficult to obtain the processing accuracy of the etching mask, which hinders miniaturization of the optical functional element. In addition, as a technique for suppressing the above problem, although a method using a metal film having a low etching rate as a mask material is known, the metal element which is a constituent element of the metal mask is nonvolatile during the etching of the compound semiconductor film. May adhere to the workpiece as a compound of the above, and the characteristics of the optical integrated device may be greatly impaired.

  In addition to the above-mentioned problems, before the compound semiconductor etching process, an altered layer, which is a layer different from the bulk region, may be formed on the processing surface by various processes used for forming the mask pattern. When such an altered layer has an etching rate lower than that of the bulk region, there is a possibility that the portion of the compound semiconductor covered by the altered layer becomes a residue.

  The present invention has been made in view of the above problems, and provides a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method that improve the workability of a compound semiconductor by dry etching.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The semiconductor device manufacturing apparatus according to claim 1 is a mixed gas comprising two components of a vacuum chamber containing a compound semiconductor containing indium and having a mask formed thereon, and hydrogen iodide gas and boron trichloride gas. A gas supply unit for supplying the first gas to the vacuum chamber and a high-frequency electric field for generating an induction electric field for supplying high-frequency power to the high-frequency antenna to turn the gas in the vacuum chamber into a plasma is applied to the vacuum chamber A high-frequency power source that performs a bias power source that applies to the chamber an electric field that causes the plasma generated in the vacuum chamber to enter the compound semiconductor, and the plasma that is generated in the vacuum chamber includes the first gas. Semiconductor device manufacturing apparatus for manufacturing a semiconductor device by etching the compound semiconductor by being incident on a semiconductor A is, and summarized in that the blending ratio which is the ratio of flow rate of the hydrogen iodide gas to the total flow rate of the first gas 40% to 60%.

  Indium iodide, which is a compound of indium and iodine, and indium chloride, which is a compound of indium and chlorine, are compounds that can be evaporated from room temperature under vacuum, and in order to improve the etching rate of compound semiconductors containing indium. It is preferable to use iodine or chlorine as an etching source. On the other hand, since the time of exposure to the iodine or chlorine plasma becomes longer as it is closer to the surface of the compound semiconductor, the ion incidence is possible even when the plasma incident on the compound semiconductor has anisotropy. In order to obtain a processed shape along the direction and flatness thereof, it is necessary to sequentially form a protective film on a portion close to the surface of the compound semiconductor in order to compensate for the plasma irradiation time difference in the incident direction. According to the above-described configuration, indium hydride or indium boride functions as a film formation seed for such a protective film, and thus is an index of the ratio between the amount of these film formation seeds and the amount of the etching source. By setting the blending ratio to 40% to 60%, the workability of the compound semiconductor can be improved.

  The semiconductor device manufacturing apparatus according to claim 2, wherein the gas supply unit supplies a second gas, which is a gas containing argon or xenon, into the vacuum chamber, and the plasma is formed of the first gas. In summary, before the compound semiconductor is incident on the compound semiconductor and the compound semiconductor is etched, the plasma of the second gas is incident on the compound semiconductor and the compound semiconductor is etched.

In the process of forming a mask on the surface of the compound semiconductor, the surface of the compound semiconductor is subjected to various processes such as a film formation process, an exposure process, a development process, and an etching process. A deteriorated layer different from the bulk region is formed. Since such a deteriorated layer has a different composition and structure from the bulk region, it is easy to make a large difference in the etching rate. Therefore, it can be a major factor for generating a residue in the subsequent etching using the first gas. According to the configuration described above, Ar or Xe plasma, in which physical etching is dominant, is incident on the surface of the compound semiconductor in advance before the plasma composed of the first gas is incident on the surface of the compound semiconductor. Therefore, such a deteriorated layer can be easily removed as compared with the case of using chemical etching. In addition, such physical etching can etch even the surface where the deteriorated layer is not formed when etching the deteriorated layer, so that the surface of the compound semiconductor before the etching with the first gas is performed. The flatness in can be maintained.

  The semiconductor device manufacturing apparatus according to claim 3, wherein the second gas is selected from the group consisting of hydrogen iodide gas, boron trichloride gas, carbon tetrachloride gas, hydrogen chloride gas, hydrogen bromide gas, and chlorine. The gist is that the mixed gas contains at least one kind of gas.

  When etching the deteriorated layer, various constituent elements contained in the deteriorated layer and the bulk region are ejected as particles. Therefore, when such particles adhere to the compound semiconductor again, the subsequent first This can be a major factor in generating residues in etching with gas. According to the above-described configuration, since the second gas contains iodine or chlorine which is an indium etching source, particles ejected by physical etching can be removed as a volatile compound.

The semiconductor device manufacturing apparatus according to claim 4, wherein the temperature of the compound semiconductor is set to 20 ° C. to 150 ° C. when the compound semiconductor is etched by causing the plasma made of the first gas to enter the compound semiconductor. The gist is that a temperature control mechanism is provided.
According to such a configuration, thermal damage to the compound semiconductor can be suppressed.

  According to a fifth aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: forming a mask on a compound semiconductor containing indium, and generating a plasma composed of a first gas which is a mixed gas of two components of hydrogen iodide gas and boron trichloride. A semiconductor device manufacturing method for manufacturing a semiconductor device by making the compound semiconductor incident on the compound semiconductor and selectively etching the compound semiconductor, wherein a ratio of a flow rate of the hydrogen iodide gas to a total flow rate of the mixed gas The gist is that the blending ratio is 40% to 60%.

  Indium iodide, which is a compound of indium and iodine, and indium chloride, which is a compound of indium and chlorine, are compounds that can be evaporated from room temperature under vacuum, and in order to improve the etching rate of compound semiconductors containing indium. It is preferable to use iodine or chlorine as an etching source. On the other hand, since the time of exposure to the iodine or chlorine plasma becomes longer as it is closer to the surface of the compound semiconductor, the ion incidence is possible even when the plasma incident on the compound semiconductor has anisotropy. In order to obtain a processed shape along the direction and flatness thereof, it is necessary to sequentially form a protective film on a portion close to the surface of the compound semiconductor in order to compensate for the plasma irradiation time difference in the incident direction. According to the above-described configuration, indium hydride or indium boride functions as a film formation seed for such a protective film, and thus is an index of the ratio between the amount of these film formation seeds and the amount of the etching source. By setting the blending ratio to 40% to 60%, the workability of the compound semiconductor can be improved.

  7. The method of manufacturing a semiconductor device according to claim 6, wherein the second gas is a gas containing argon or xenon before the plasma of the first gas is incident on the compound semiconductor to etch the compound semiconductor. The gist of the present invention is to etch the compound semiconductor by making the plasma comprising the above incident on the compound semiconductor.

In the process of forming a mask on the surface of the compound semiconductor, the surface of the compound semiconductor is subjected to various processes such as a film formation process, an exposure process, a development process, and an etching process. A deteriorated layer different from the bulk region is formed. Since such a deteriorated layer has a different composition and structure from the bulk region, it is easy to make a large difference in the etching rate. Therefore, it can be a major factor for generating a residue in the subsequent etching using the first gas. According to the configuration described above, Ar or Xe plasma, in which physical etching is dominant, is incident on the surface of the compound semiconductor in advance before the plasma composed of the first gas is incident on the surface of the compound semiconductor. Therefore, such a deteriorated layer can be easily removed as compared with the case of using chemical etching. In addition, such physical etching can etch even the surface where the deteriorated layer is not formed when etching the deteriorated layer, so that the surface of the compound semiconductor before the etching with the first gas is performed. The flatness in can be maintained.

  The method of manufacturing a semiconductor device according to claim 7, wherein the second gas is selected from the group consisting of hydrogen iodide gas, boron trichloride gas, carbon tetrachloride gas, hydrogen chloride gas, hydrogen bromide gas, and chlorine. The gist is that the mixed gas contains at least one kind of gas.

  When etching the deteriorated layer, various constituent elements contained in the deteriorated layer and the bulk region are ejected as particles. Therefore, when such particles adhere to the compound semiconductor again, the subsequent first This can be a major factor in generating residues in etching with gas. According to the above-described configuration, since the second gas contains iodine or chlorine which is an indium etching source, particles ejected by physical etching can be removed as a volatile compound.

The method of manufacturing a semiconductor device according to claim 8, wherein the temperature of the compound semiconductor is set to 20 ° C. to 150 ° C. when the compound semiconductor is etched by causing the plasma made of the first gas to enter the compound semiconductor. This is the gist.
According to such a configuration, thermal damage to the compound semiconductor can be suppressed.

  As described above, according to the present invention, it is possible to provide a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method that improve the workability of a compound semiconductor by dry etching.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. 1A to 1E are process diagrams for explaining a method of manufacturing a semiconductor device.
As shown in FIG. 1, first, a mask film 11 is formed on an etching object 10, and a resist film 12 is laminated on the mask film 11 (see FIG. 1A). Next, when the mask film 11 is formed, a resist pattern 12P is formed by applying a photolithography method to the resist film 12, and then an etching process using the resist pattern 12P as a mask is performed on the mask film 11. As a result, a mask pattern 11P is formed (see FIG. 1B).

  The etching object 10 is an indium-based group 3-5 compound semiconductor, and is selected from the group consisting of indium phosphide (InP), or aluminum (Al), gallium (Ga), arsenic (As), and phosphorus (P). A ternary or quaternary indium compound composed of the above element and In, such as InGaAlAs and InGaAsP. Such an object to be etched 10 may be composed of a single semiconductor layer, or may be composed of a laminated body composed of a plurality of compound semiconductor layers having different compositions. Further, it may be a single layer or a plurality of layers grown on a single crystal substrate, or a plurality of types of growth layer structures formed in parallel on a single crystal substrate.

The mask film 11 is made of silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), or the like from the viewpoint of increasing the selectivity, which is the ratio between the etching rate of the etching target 10 and the etching rate of the mask film 11. Inorganic dielectric materials can be used. Such a mask film 11 can be obtained by forming an inorganic dielectric film on the surface of the etching object 10 by applying a film forming technique such as sputtering or CVD.

The resist film 12 can be formed by applying a resist material on the mask film 11 and drying, and the resist pattern 12P can be formed by exposing and developing the resist film 12. The mask pattern 11P uses the resist pattern 12P as a mask to perform a dry etching process using a fluorine-based gas such as carbon tetrafluoride (CF ₄ ) on the mask film 11, and then removes the resist pattern 12P. Can be obtained. When an inorganic dielectric material is used as the mask film 11, the ratio of the etching rate of the mask film 11 to the etching rate of the resist film 12 is used from the viewpoint of increasing the accuracy and density of the mask pattern 11P. It is preferable to reduce the film thickness of the mask film 11 in consideration of a certain selection ratio, and the film thickness is preferably set in the range of 50 nm to 1 μm.

  When the mask pattern 11P is formed, a pre-etching process (first step) that is an etching process using a rare gas such as argon (Ar) or xenon (Xe) is performed on the etching object 10 (FIG. 1). (See (c)). The pre-etching step is a step for cleaning the surface of the etching target 10 having the mask pattern 11P and improving workability in the subsequent main etching step.

  On the surface of the etching target object 10 having the mask pattern 11P, there are formed a number of altered layers different from the bulk region of the etching target object 10 by various processes for forming the mask pattern 11P. Since such a deteriorated layer has a different composition and structure from the bulk region, it is easy to make a large difference in the etching rate. Therefore, a residue is easily generated in the subsequent bulk region etching process, that is, the main etching process. The pre-etching step is a step for removing such a deteriorated layer.

  In the pre-etching process, in order to maintain the flatness of the surface of the object 10 to be etched, physical etching is performed so that even the surface where the altered layer is not formed is etched in the same manner. This is performed by exposing the surface of the etching object 10 to the same space using the plasma EP1 of the gas containing Ar or Xe (second gas) in which is dominant. In order to ensure the stability of the high-density plasma in this pre-etching step, a configuration in which the pressure during etching is adjusted to 0.7 Pa to 1.2 Pa is preferable.

As an etching gas used in the pre-etching process, only Ar or Xe may be used in order to effectively perform physical etching. Further, the physical etching object to be etched again is reattached. Selected from the group consisting of hydrogen iodide (HI), boron trichloride (BCl ₃ ), carbon tetrachloride (CCl ₄ ), hydrogen chloride (HCl), hydrogen bromide (HBr), and chlorine (Cl ₂ ). The form using at least 1 sort (s) of halogen gas with said Ar and Xe may be sufficient. In addition, when the deteriorated layer is not formed on the surface of the etching target object 10, the pre-etching process described above may be omitted.

  When the pre-etching process is completed, a main etching process (second step) using hydrogen iodide (HI) is performed on the object to be etched 10 to form a processing pattern 10P (FIG. 1D). (See (e)). The main etching process is a process for performing etching using the mask pattern 11P as a mask on the surface of the etching target 10 cleaned by the pre-etching process.

In the main etching process, a region (etching region) other than the region covered with the mask pattern 11P is etched from the two-component system of HI and BCl ₃ so as to be etched along the normal direction (vertical direction) of the surface. The surface of the etching object 10 is exposed to plasma EP2 using a mixed gas (first gas) that is a mixed gas in which the mixing ratio of the flow rate of HI to the total flow rate of the mixed gas is 40% to 60%. It is executed by. From the viewpoint of ensuring the stability of high-density plasma in this main etching step, a configuration in which the pressure during etching is adjusted to 0.7 Pa to 1.2 Pa is preferable.

  The present inventors have found through various experiments and the like that the indium iodide under the pressure of 0.7 Pa to 1.2 Pa evaporates when heated to 20 ° C. or higher. In order to promote the separation of such indium iodide and improve the flatness of the processing surface, the processing temperature of the etching object 10 is set in the range of 20 ° C. to 400 ° C. in the main etching step. In addition, in order to suppress the thermal damage of the etching target object 10, it is more preferable to adjust the said processing temperature to 20 to 150 degreeC.

Further, the present inventor has found that indium boride under the above pressure range and temperature range functions as a film-forming species by various experiments. In order to proceed the etching along the vertical direction by using such a film formation seed, in other words, the indium boride as the film formation seed is attached to the side wall of the etched portion to suppress isotropic etching. Therefore, in the main etching step, the mixing ratio of the flow rate of the HI is set to 40% to 60%. Incidentally, since the formation of indium boride, which is the film-forming species, can be suppressed by increasing the amount of chlorine (Cl) in the plasma, the side wall is protected by reducing the flow rate mixture ratio of HI to less than 40%. When the action becomes excessive, it is possible to adjust the deposition amount of the side wall protection by adding chlorine (Cl ₂ ) to the plasma generation region AP.

  In the pre-etching process and the main etching process described above, inductively coupled plasma, microwave-excited surface wave plasma, electron cyclotron that independently control the plasma density in the plasma space and the incident energy of ions incident on the etching object 10 are used. Ton mirror surface plasma and helicon wave excitation plasma can be used. Particularly in inductively coupled plasma, a method of applying a static magnetic field capable of controlling the plasma density distribution in the plasma space is more preferable.

  Next, the plasma etching apparatus 20 which is a semiconductor device manufacturing apparatus used for the pre-etching process and the main etching process described above will be described. FIG. 2 is a diagram showing a schematic configuration of the plasma etching apparatus 20.

  As shown in FIG. 2, a quartz plate 22 is attached to the upper opening of the vacuum chamber 21 in the plasma etching apparatus 20 so as to seal the plasma generation region AP that is the internal space of the vacuum chamber 21. A plasma generation region AP surrounded by the substrate 21 and the quartz plate 22 is depressurized to a predetermined pressure by an exhaust system including a vacuum pump or the like.

A substrate holder 23 for supporting the etching object 10 having the mask pattern 11P is disposed in the plasma generation region AP. The substrate holder 23 is connected to a bias power source via a bias matching circuit 24. It is electrically connected to a certain high frequency power supply 25 for bias. The high frequency power output from the bias high frequency power supply 25 is applied to the etching object 10 via the substrate holder 23 after impedance matching is performed by the bias matching circuit 24 so that the reflected wave from the load side becomes small. The Substrate holder 2
A ring-shaped protective member 26 that surrounds the outer periphery of the etching object 10 is disposed on the mounting surface of the etching object 10, which is the upper surface of 3. The protective member 26 has a function of protecting the outer peripheral portion of the substrate holder 23 from the plasmas EP1 and EP2 generated in the plasma generation region AP. For example, the glassy carbon having high resistance to chlorine-based or iodine-based plasma. Can be configured. In addition, a temperature control mechanism (not shown) for adjusting the temperature of the etching target 10 to a predetermined temperature is mounted inside the substrate holder 23, and the pre-etching process conditions (pre-etching conditions) and the main etching process are controlled. A temperature based on the processing conditions (main etching conditions) is applied to the etching object 10 by the temperature control of the temperature control mechanism.

  A high-frequency loop antenna 27 that forms a two-turn loop is disposed above the quartz plate 22 described above, and is coaxial with the high-frequency loop antenna 27 between the high-frequency loop antenna 27 and the quartz plate 22. The loop permanent magnets 28 are arranged in parallel with the surface of the quartz plate 22. The high-frequency loop antenna 27 is electrically connected to a discharging high-frequency power source 31 via a discharging matching circuit 29, and the high-frequency power output from the discharging high-frequency power source 31 has a small reflected wave from the load side. As described above, impedance matching is performed by the discharge matching circuit 29 and then applied to the high-frequency loop antenna 27. The high-frequency power applied to the high-frequency loop antenna 27 applies a high-frequency electric field that generates an induction electric field for generating plasma using the gas supplied to the plasma generation region AP to the plasma generation region AP, and loop-shaped permanent magnets 28 forms a static magnetic field in a direction substantially orthogonal to the current flowing through the high-frequency loop antenna 27 in the plasma generation region AP.

Between the quartz plate 22 and the loop-shaped permanent magnet 28, a planar electrode 32 having substantially the same diameter as the quartz plate 22 is disposed in parallel with the surface of the quartz plate 22, and this planar electrode Reference numeral 32 is electrically connected to the discharging high-frequency power source 31 through a variable capacitor 33 and the discharging matching circuit 29. The planar electrode 32 has a function of forming a uniform electric field on the inner surface of the quartz plate 22 can be constituted for example by a linear metallic material.

A gas supply unit 34 for supplying a mixed gas used in the pre-etching process and the main etching process is connected to the plasma generation region AP of the vacuum chamber 21. This gas supply unit 34 is used for Ar and Xe used in the pre-etching step, and further boron trichloride (BCl ₃ ), chlorine (Cl ₂ ), carbon tetrachloride (CCl ₄ ), hydrogen chloride (HCl), bromide At least one halogen gas selected from the group consisting of hydrogen (HBr) is supplied in a predetermined blending ratio with a mixed gas of Ar and Xe. Further, the gas supply unit 34 supplies a mixed gas composed of a binary system of HI and BCl ₃ used in the main etching process so that the mixing ratio of the flow rate of HI to the total flow rate is 40% to 60%. .

The control unit 40 in the plasma etching apparatus 20 is connected to the substrate holder 23, the bias matching circuit 24, the bias high frequency power supply 25, the discharge matching circuit 29, the discharge high frequency power supply 31, and the variable capacitor 33. each seed control signal based on the pre-etch condition and main etching conditions are outputted from the control unit 40 to the respective units.

  For example, the control unit 40 refers to the pre-etching conditions stored in the internal storage area and outputs a control signal for applying a temperature based on the conditions to the etching target 10 to the temperature adjustment mechanism of the substrate holder 23. When the pre-etching process is performed, the temperature adjustment mechanism is caused to execute temperature adjustment based on the control signal. Further, the control unit 40 refers to the main etching conditions, outputs a control signal for applying a temperature based on the conditions to the etching object 10 to the temperature control mechanism of the substrate holder 23, and performs the main etching process. Causes the temperature adjustment mechanism to execute temperature adjustment based on the control signal.

  The control unit 40 outputs a control signal for applying high-frequency power based on pre-etching conditions to the etching target 10 to the bias high-frequency power source 25. Output high frequency power. Further, the control unit 40 outputs a control signal for supplying a two-component mixed gas composed of HI and BCl3 at a mixing ratio of the main etching conditions to the gas supply unit 34, and when performing the main etching process, a bias signal is used. The high frequency power supply 25 is made to output the same high frequency power.

  Further, the control unit 40 outputs a control signal for applying high frequency power of 13.56 MHz based on the pre-etching condition to the high-frequency loop antenna 27 to the high-frequency power supply 31 for discharging. The power supply 31 is made to output the same high frequency power. Further, the control unit 40 outputs a control signal for applying high frequency power of 13.56 MHz based on the main etching condition to the high frequency loop antenna 27 to the high frequency power supply 31 for discharging, and when performing the main etching process, the high frequency for discharging is used. The power supply 31 is made to output the same high frequency power.

Further, the control unit 40 outputs a control signal for supplying, for example, a ternary mixed gas composed of Ar, HI, and BCl _{3 at} a mixing ratio of pre-etching conditions to the gas supply unit 34, and performs the pre-etching process. In this case, the gas mixture is supplied to the gas supply unit. Further, the control unit 40 outputs a control signal for supplying a two-component mixed gas composed of HI and BCl _{3 at} a mixing ratio of the main etching conditions to the gas supply unit 34, and when performing the main etching process, the gas is supplied. The mixed gas is supplied to the supply unit 34.

  Further, the control unit 40 adjusts the capacitance of the variable capacitor 33 to an optimum value within a range of 10 pF to 100 pF, thereby preventing the film from adhering to the inner surface of the quartz plate 22. Note that the variable capacitor 33 may be changed to a variable choke as long as it has such a function.

  When the pre-etching process is executed by the control unit 40 described above, the etching object 10 having the mask pattern 11P is first placed on the substrate holder 23, and gases based on pre-etching conditions, that is, Ar or Xe. Is supplied to the plasma generation region AP. Subsequently, when a high frequency power for discharge based on pre-etching conditions is applied to the high frequency loop antenna 27, a high frequency magnetic field corresponding to the high frequency power is formed in the plasma generation region AP, and an induction electric field generated by the high frequency magnetic field is generated. Gasifies the gas in the plasma generation region AP. At this time, when a high-frequency power based on pre-etching conditions is applied to the etching object 10, a bias voltage corresponding to the high-frequency power is applied to the etching object 10 and the activity in the plasma formed in the plasma generation region AP. The seed enters the surface of the etching object 10. By exposing the etching object 10 to the plasma space in which such physical etching is dominant for a predetermined time, the surface of the etching object 10 including the altered layer is uniformly removed and cleaned.

When the main etching process is executed by the control unit 40, following the pre-etching process, first, a mixed gas based on the main etching conditions, that is, a mixed gas in which HI and BCl ₃ are mixed at the above mixing ratio is generated in plasma. It is supplied to the area AP. Subsequently, when a high frequency power for discharge based on the main etching condition is applied to the high frequency loop antenna 27, a high frequency magnetic field corresponding to the high frequency power is formed in the plasma generation region AP, and an induction electric field generated by the high frequency magnetic field is generated. Gasifies the gas in the plasma generation region AP. At this time, when a high-frequency power based on the main etching condition is applied to the etching target 10, a bias voltage corresponding to the high-frequency power is applied to the etching target 10 and the activity in the plasma formed in the plasma generation region AP. The seed enters the surface of the etching object 10. Since physical etching and chemical etching proceed in a well-balanced manner according to the above-described blending ratio, only the etching region on the surface of the etching target 10 is etched along the vertical direction.

  Next, the evaluation results regarding the shape of etching and the presence or absence of residues obtained using the plasma etching apparatus 20 will be described with reference to Tables 1 and 2. Table 1 shows the results when the surface of the etching object 10 does not have a deteriorated layer and the like, and only the main etching process is performed without the pre-etching process, and Table 2 shows the surface of the etching object 10. Shows a result when the pre-etching step (first step) and the main etching step (second step) are successively performed in a form having a deteriorated layer.

  In the shape evaluation in Tables 1 and 2, “◯” indicates the shape along which the side wall of the processing pattern 10P extends in the vertical direction (the shape formed by the angle with the normal line is within ± 3 °), and the processing pattern It shows that the bottom of 10P is substantially horizontal. “Δ” indicates that the side wall of the processed pattern 10P is tapered (the angle formed by the normal line exceeds ± 3 °), or the bottom of the processed pattern 10P is bowl-shaped. "" Indicates that the side wall of the processing pattern 10P is tapered and the bottom of the processing pattern 10P is bowl-shaped.

In the residue evaluation in Tables 1 and 2, “◯” indicates that no residue was found on the side wall or bottom of the processed pattern 10P, and “X” indicates granular particles attached to the side wall or bottom of the processed pattern 10P. It is shown that a residue in the form of a column or a columnar residue protruding from the bottom was observed. Example 1
A SiO ₂ film having a film thickness of 500 nm is formed as a mask film 11 on the surface of the InP substrate that is the etching object 10 by applying a thermal CVD method, and stripes are formed so that the SiO ₂ film has a line width of 1.5 μm. A mask pattern 11P made of SiO ₂ was obtained. Then, after performing a predetermined cleaning process on the surface of the etching target 10, the following conditions are used as the main etching conditions, and the main etching process is performed for a processing time in which the width in the depth direction of the processed pattern 10P is about 4 μm. As a result, a processed pattern 10P of Example 1 was obtained. Regarding the processing pressure, three different values including 0.7 Pa and 1.2 Pa from the range of 0.7 Pa to 1.2 Pa are set as the main etching conditions, and for the high frequency power for biasing, 10 W to 50 W. From these ranges, three different values including 10 W and 50 W were set as the main etching conditions.
[Main etching conditions]
HI flow rate: 12 sccm (composition ratio 40%), BCl ₃ flow rate: 18 sccm
・ Processing pressure: 0.7 Pa to 1.2 Pa
・ Processing temperature: 120 ℃
・ High frequency power for discharge: 250W
・ High frequency power for bias: 10W to 50W
(Example 2 to Example 6)
The processing pattern 10P of Example 2 was obtained in the same manner as in Example 1 except that the HI flow rate was changed to 15 sccm (blending ratio 50%), the BCl ₃ flow rate was changed to 15 sccm. Further, the processing flow 10P of Example 3 was obtained in the same manner as in Example 1 except that the HI flow rate was changed to 18 sccm (mixing ratio 60%) and the BCl ₃ flow rate was changed to 12 sccm.

The HI flow rate was changed to 20 sccm (composition ratio 40%), the BCl ₃ flow rate was changed to 30 sccm, the high frequency power for bias was changed to 50 W to 100 W, and other conditions were the same as in Example 1 and the processing pattern of Example 4 10P was obtained. The processing flow 10P of Example 5 was obtained in the same manner as in Example 4 except that the HI flow rate was changed to 25 sccm (blending ratio 50%) and the BCl ₃ flow rate was changed to 25 sccm. Further, the processing pattern 10P of Example 6 was obtained in the same manner as in Example 4 except that the HI flow rate was changed to 30 sccm (mixing ratio 60%) and the BCl ₃ flow rate was changed to 20 sccm.
(Comparative Examples 1 to 4)
The processing pattern 10P of Comparative Example 1 was obtained in the same manner as in Example 1 except that the HI flow rate was changed to 10 sccm (compounding ratio 33%) and the BCl ₃ flow rate was changed to 20 sccm. Further, the processing flow 10P of Comparative Example 2 was obtained in the same manner as in Example 1 except that the HI flow rate was changed to 20 sccm (combination ratio 67%) and the BCl ₃ flow rate was changed to 10 sccm.

The processing pattern 10P of Comparative Example 3 was obtained in the same manner as in Example 4 except that the HI flow rate was changed to 15 sccm (composition ratio 30%) and the BCl ₃ flow rate was changed to 35 sccm. Further, the processing pattern 10P of Comparative Example 4 was obtained in the same manner as in Example 4 except that the HI flow rate was changed to 35 sccm (mixing ratio 70%), the BCl ₃ flow rate was changed to 15 sccm.

  As shown in Table 1, in each of Examples 1 to 6, it was recognized that the side wall of the processed pattern 10P had a shape along the substantially vertical direction, and the bottom of the processed pattern 10P was substantially horizontal. . Moreover, in Example 1- Example 6, it turned out that the residue accompanying etching is not produced | generated all. On the other hand, in Comparative Example 1 and Comparative Example 3, it was recognized that the side wall of the processed pattern 10P was tapered. Further, in both Comparative Example 1 and Comparative Example 3, granular residues accompanying etching were observed. As a result, it is understood that the workability of the processing pattern 10P can be improved by using the mixed gas in which the mixing ratio of the flow rate of HI to the total flow rate of the mixed gas is 40% to 60%.

The above-described effects are not limited to the case where the etching object 10 is InP, but the same effect is observed when the etching object 10 is InGaAlAs or InGaAsP. Furthermore, the mask pattern 11P is SiO _2. The same effect was observed not only when using Si ₃ N ₄ but also when using Si ₃ N ₄ .

  Further, in the case of using a mixed gas whose blending ratio based on the flow rate of HI is 40% to 60%, the selection ratio that is the ratio of the etching rate of the etching object 10 to the etching rate of the mask pattern 11P is 20 or more. It was found to be a sufficiently high value. In the case of using a mixed gas whose blending ratio based on the flow rate of HI is 40% to 60%, the etching rate ratio which is the ratio of the etching rate Ex of InGaAlAs or InGaAsP to the etching rate Er of InP is 1.0. It is recognized that the etching object 10 is composed of a stacked body composed of a plurality of compound semiconductor layers having different compositions, such as InP / InGaAlAs / InP or InP / InGaAsP / InP. Even in this case, it has been found that the same effect as described above can be obtained.

（実施例７〜実施例９）
エッチング対象物１０であるＩｎＰ基板の表面に熱ＣＶＤ法を適用して膜厚が５００ｎｍのＳｉＯ_２膜をマスク膜１１として形成し、このＳｉＯ_２膜が１．５μｍの線幅を持つようにストライプ状に加工してＳｉＯ_２からなるマスクパターン１１Ｐを得た。そして、以下に示すプリエッチング条件を用いてプリエッチング工程を実行し、次いで以下に示すメインエッチング条件を用いて加工パターン１０Ｐの深さ方向の幅が約４μｍとなる処理時間だけメインエッチング工程を実行することにより実施例７の加工パターン１０Ｐを得た。
［プリエッチング条件］
・Ａｒ流量：７０ｓｃｃｍ、ＨＩ流量：１８ｓｃｃｍ、ＢＣｌ_３流量：１２ｓｃｃｍ
・処理圧力：０．５Ｐａ
・処理温度：１２０℃
・放電用高周波電力：２５０Ｗ
・バイアス用高周波電力：５０Ｗ
・処理時間：５秒
［メインエッチング条件］
・ＨＩ流量：１２ｓｃｃｍ（配合比４０％）、ＢＣｌ_３流量：１８ｓｃｃｍ
・処理圧力：０．７Ｐａ
・処理温度：１２０℃
・放電用高周波電力：２５０Ｗ
・バイアス用高周波電力：５０Ｗ
またプリエッチング条件及びメインエッチング条件におけるＨＩ流量を１５ｓｃｃｍ、ＢＣｌ_３流量を１５ｓｃｃｍ、処理時間を３０秒に変更し、その他の条件を実施例７と同じくして実施例８の加工パターン１０Ｐを得た。またプリエッチング条件におけるＡｒ流量を５０ｓｃｃｍ、ＨＩ流量を０ｓｃｃｍ、ＢＣｌ_３流量を０ｓｃｃｍに変更し、その他の条件を実施例７と同じくして実施例９の加工パターン１０Ｐを得た。
（比較例５及び比較例６）
またプリエッチング条件におけるＨＩ流量を０ｓｃｃｍ、ＢＣｌ_３流量を０ｓｃｃｍに変更し、その他の条件を実施例８と同じくして比較例５の加工パターン１０Ｐを得た。またプリエッチング条件におけるＡｒ流量を０ｓｃｃｍ、処理圧力を０．７Ｐａ、処理時間を３分に変更し、その他の条件を実施例７と同じくして比較例６の加工パターン１０Ｐを
得た。

(Example 7 to Example 9)
A SiO ₂ film having a film thickness of 500 nm is formed as a mask film 11 on the surface of the InP substrate that is the etching object 10 by applying a thermal CVD method, and stripes are formed so that the SiO ₂ film has a line width of 1.5 μm. A mask pattern 11P made of SiO ₂ was obtained. Then, the pre-etching process is executed using the pre-etching conditions shown below, and then the main etching process is executed using the main etching conditions shown below for a processing time in which the width in the depth direction of the processed pattern 10P is about 4 μm. As a result, a processed pattern 10P of Example 7 was obtained.
[Pre-etching conditions]
Ar flow rate: 70 sccm, HI flow rate: 18 sccm, BCl ₃ flow rate: 12 sccm
・ Processing pressure: 0.5Pa
・ Processing temperature: 120 ℃
・ High frequency power for discharge: 250W
・ High frequency power for bias: 50W
・ Processing time: 5 seconds [Main etching conditions]
HI flow rate: 12 sccm (composition ratio 40%), BCl ₃ flow rate: 18 sccm
・ Processing pressure: 0.7Pa
・ Processing temperature: 120 ℃
・ High frequency power for discharge: 250W
・ High frequency power for bias: 50W
Further, the HI flow rate in the pre-etching condition and the main etching condition was changed to 15 sccm, the BCl ₃ flow rate was changed to 15 sccm, the processing time was changed to 30 seconds, and the other conditions were the same as in Example 7 to obtain the processing pattern 10P of Example 8. . Further, the Ar flow rate under pre-etching conditions was changed to 50 sccm, the HI flow rate was changed to 0 sccm, the BCl ₃ flow rate was changed to 0 sccm, and the other conditions were the same as in Example 7 to obtain a processed pattern 10P of Example 9.
(Comparative Example 5 and Comparative Example 6)
Further, the HI flow rate under pre-etching conditions was changed to 0 sccm, the BCl ₃ flow rate was changed to 0 sccm, and the other conditions were the same as in Example 8 to obtain a processed pattern 10P of Comparative Example 5. Further, the Ar flow rate under pre-etching conditions was changed to 0 sccm, the processing pressure was changed to 0.7 Pa, the processing time was changed to 3 minutes, and the other conditions were the same as in Example 7 to obtain a processed pattern 10P of Comparative Example 6.

As shown in Table 2, in each of Examples 7 to 9, it is recognized that the sidewall of the processed pattern 10P has a shape along the substantially vertical direction, and the bottom of the processed pattern 10P is substantially horizontal, and etching is performed. It was found that the residue associated with was not produced. On the other hand, in both Comparative Example 5 and Comparative Example 6, although the shape evaluation was “◯”, columnar residues accompanying etching were observed in both cases. As a result, it is understood that the altered layer or the like caused by the columnar residue can be cleaned by exposing the surface of the object to be etched 10 to the surface of the etching target 10 with Ar plasma in which physical etching is dominant before performing the main etching process. . Further, in a surface state that requires such a pre-etching process for a long time, the etching is performed in order to suppress the reattachment of the physically etched object by comparison between Example 8 and Comparative Example 5. It can be seen that it is effective to add HI and BCl ₃ which can make the product a volatile compound.

以上説明したように、上記実施形態によれば以下の効果を奏する。

As described above, according to the above embodiment, the following effects can be obtained.

  (1) According to the above embodiment, since the In hydride or the In boride functions as a film forming seed for the protective film protecting the side wall of the processed surface, the amount of these film forming seeds and the etching source By adjusting the blending ratio, which is an index of the ratio of iodine and boron, to 40% to 60%, the workability of the compound semiconductor can be improved.

  (2) According to the above-described embodiment, in order to cause the plasma made of the second gas, which is a gas containing Ar or Xe, to enter the etching object 10 before the main etching process, The formed altered layer can be etched in advance. In addition, since the deteriorated layer is etched using physical etching, the surface on which the deteriorated layer is not formed can also be etched, and before the main etching step is performed, the surface on the surface of the object to be etched 10 is flattened. Sex can be maintained.

(3) According to the above embodiment, since at least one halogen gas selected from the group consisting of HI, BCl ₃ , CCl ₄ , HCl, HBr, and Cl ₂ is added to the pre-etching process, Reattachment of the etched object to be etched can be suppressed.

(A)-(e) is process drawing which shows the manufacturing method of the semiconductor device in this embodiment, respectively. The figure which shows schematic structure of the manufacturing apparatus of the semiconductor device in this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Etching object, 11 ... Mask film, 11P ... Mask pattern, 12 ... Resist film, 12P ... Resist pattern, 20 ... Etching apparatus, 21 ... Vacuum chamber, 22 ... Quartz plate, 23 ... Substrate holder, 24 ... For bias Matching circuit, 25 ... high frequency power supply for bias, 26 ... protective member, 27 ... high frequency loop antenna, 28 ... loop-shaped permanent magnet, 29 ... matching circuit for discharge, 31 ... high frequency power supply for discharge, 32 ... planar electrode, 33 ... Variable capacitor, 34... Gas supply unit, 40.

Claims (8)

A vacuum chamber containing a compound semiconductor containing indium and having a mask formed thereon;
A gas supply unit for supplying a first gas, which is a mixed gas composed of two components of hydrogen iodide gas and boron trichloride gas, to the vacuum chamber;
A high-frequency power source that applies a high-frequency electric field to the vacuum chamber to generate an induction electric field that supplies high-frequency power to the high-frequency antenna to plasmaize the gas in the vacuum chamber;
A bias power source that applies an electric field that causes the plasma generated in the vacuum chamber to be incident on the compound semiconductor;
A semiconductor device manufacturing apparatus for manufacturing a semiconductor device by causing plasma generated from the first gas generated in the vacuum chamber to enter the compound semiconductor and etching the compound semiconductor,
An apparatus for manufacturing a semiconductor device, wherein a blending ratio, which is a ratio of a flow rate of the hydrogen iodide gas to a total flow rate of the first gas, is set to 40% to 60%. A manufacturing apparatus for a semiconductor device according to claim 1,
The gas supply unit supplies a second gas, which is a gas containing argon or xenon, into the vacuum chamber;
Before the plasma made of the first gas is incident on the compound semiconductor and the compound semiconductor is etched, the plasma made of the second gas is made incident on the compound semiconductor and the compound semiconductor is etched. Semiconductor device manufacturing equipment. The second gas is a mixed gas containing at least one gas selected from the group consisting of hydrogen iodide gas, boron trichloride gas, carbon tetrachloride gas, hydrogen chloride gas, hydrogen bromide gas, and chlorine. An apparatus for manufacturing a semiconductor device according to claim 2. It is a manufacturing apparatus of the semiconductor device according to any one of claims 1 to 3,
A semiconductor device comprising a temperature adjustment mechanism that causes the temperature of the compound semiconductor to be 20 ° C. to 150 ° C. when the compound semiconductor is etched by causing the plasma made of the first gas to enter the compound semiconductor. Manufacturing equipment. A mask is formed on a compound semiconductor containing indium, and a plasma composed of a first gas, which is a mixed gas of two components of hydrogen iodide gas and boron trichloride, is incident on the compound semiconductor to selectively select the compound semiconductor. A semiconductor device manufacturing method for manufacturing a semiconductor device by etching into a semiconductor device,
A method for manufacturing a semiconductor device, wherein a mixing ratio, which is a ratio of a flow rate of the hydrogen iodide gas to a total flow rate of the mixed gas, is 40% to 60%. A method of manufacturing a semiconductor device according to claim 5,
Before the plasma made of the first gas is incident on the compound semiconductor to etch the compound semiconductor, the plasma made of the second gas that is a gas containing argon or xenon is made incident on the compound semiconductor. A method of manufacturing a semiconductor device, comprising etching a semiconductor. The second gas is a mixed gas containing at least one gas selected from the group consisting of hydrogen iodide gas, boron trichloride gas, carbon tetrachloride gas, hydrogen chloride gas, hydrogen bromide gas, and chlorine. A method for manufacturing a semiconductor device according to claim 6. A method for manufacturing a semiconductor device according to any one of claims 5 to 7,
A method of manufacturing a semiconductor device, characterized in that a temperature of the compound semiconductor is set to 20 ° C. to 150 ° C. when the compound semiconductor is etched by causing plasma made of the first gas to enter the compound semiconductor.

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