Dry etching method and apparatus

Description

BACKGROUND OF THE PRESENT INVENTION

[0001] The present invention relates to a process of manufacturing compound semiconductor, relates to a dry etching method for fabricating InP or epitaxially grown thin film thereof with satisfactory controllability and anisotropically, and particularly relates to a dry etching method and apparatus using ions generated by an induction coupling plasma (ICP) source or. plasma having a high frequency in bands of VHF, UHF, and the like.

[0002] Etching fabrication techniques for compound semiconductor are used for manufacturing of various compound semiconductor elements such as semiconductor laser and optical modulator. Though wet etching has been employed for etching of compound semiconductor for a long time, increasing demand for improvement in uniformity of fabrication dimensions in wafer surfaces in recent years has promoted studies of dry etching techniques.

[0003] Because of demand for miniaturization of and dry process for such compound semiconductor devices, etching techniques superior in microfabrication property and selectivity on types of material and controllability on high-speed process or etching shape have become particularly important in processes of manufacturing HBT (Heterojunction Bipolar Transistor), HEMT (High Electron. Mobility Transistor) and the like that have been increasing in performance with miniaturization.

[0004] As dry etching methods for compound semiconductor as prior arts have been used reactive ion etching (RIE), reactive ion beam etching (RIBE), and the like with use of mixed gas of chlorine-based gas and of inert gas such as argon, mixed gas of methane or halomethane and of hydrogen, or the like.

[0005] Control of anisotropy of fabrication shape, however, requires supply of considerable electric power, which may do plasma damage onto surfaces of substrates or thin films and may make it difficult to ensure flatness (specularity) of the surfaces.

[0006] For via hole fabrication that is extremely important for high-speed operation (electron mobility) of HEMT devices using InP, on the other hand, deep etching fabrication is required, for example, with a depth at least not less than 20 μm, more preferably, not less than 100 μm. In other words, highly selective process is required and high-speed etching is indispensable for resist mask; however, it is difficult to carry out such treatment within a desired period of time with RIE plasma of the mixed gas of methane or halomethane and of hydrogen. In addition, it has conventionally been difficult to obtain satisfactory fabrication shapes in etching of InP material with chlorine-based gas. That is because a vapor pressure of chloride of In has been low.

[0007] Therefore, an object of the present invention is to solve issues described above and to provide a dry etching method and apparatus that are capable of performing deep etching fabrication rapidly on a substrate of InP-based compound semiconductor.

SUMMARY OF THE PRESENT INVENTION

[0008] In order to achieve the object, the present invention is configured as follows.

[0009] According to a first aspect of the present invention, there is provided a dry etching method in which etching gas is fed into a reaction chamber and exhaust of the reaction chamber is performed so that inside of the reaction chamber is controlled to be under a predetermined pressure, in which plasma is then generated in the reaction chamber by application of a 13.56 MHz or above high-frequency power to a flat spiral discharge coil that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber, in which the InP-based compound semiconductor substrate is etched while a density of the plasma is controlled by the high-frequency power applied to the discharge coil and while ion energy that reaches the InP-based compound semiconductor substrate is controlled by application of a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode with such ion energy control independent from the plasma density control, and in which mixed gas of hydrogen iodide gas and of inert gas is used as the etching gas.

[0010] According to a second aspect of the present invention, there is provided a dry etching method in which etching gas is fed into a reaction chamber and exhaust of the reaction chamber is performed so that inside of the reaction chamber is controlled to be under a predetermined pressure, in which plasma is then generated in the reaction chamber by application of a 13.56 MHz or above high-frequency power to a flat antenna that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber, in which the InP-based compound semiconductor substrate is etched while a density of the plasma is controlled by the high-frequency power applied to the antenna and while ion energy that reaches the InP-based compound semiconductor substrate is controlled by application of a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode with such ion energy control independent from the plasma density control, and in which mixed gas of gas containing chlorine or hydrogen bromide or hydrogen chloride and of inert gas is used as the etching gas.

[0011] According to a third aspect of the present invention, there is provided a dry etching method as defined in the first or second aspect, wherein an angle of inclination of via holes or recesses that are formed on the InP-based compound semiconductor substrate by etching is changed with use of different types of gas as the etching gas.

[0012] According to a fourth aspect of the present invention, there is provided a dry etching method as defined in the first aspect, wherein an angle of inclination of via holes or recesses that are formed on the substrate by etching is changed with use, as the etching gas, of a gas that is selected from a group consisting of inert gas, gas containing Cl2, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to hydrogen iodide gas.

[0013] According to a fifth aspect of the present invention, there is provided a dry etching method as defined in the second aspect, wherein an angle of inclination of via holes or recesses that are formed on the substrate by etching is changed with use, as the etching gas, of a gas that is selected from a group consisting of inert gas, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to gas containing Cl2.

[0014] According to a sixth aspect of the present invention, there is provided a dry etching method as defined in any one of the first to fifth aspects, wherein a frequency of the high-frequency power that is applied to the discharge coil or the antenna is any one of 27.12 MHz, 40.68 MHz, 60 MHz, 80 MHz, and 100 MHz.

[0015] According to a seventh aspect of the present invention, there is provided a dry etching method as defined in the first or fourth aspect, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 90° to 60° by adjustment of a degree of vacuum in the reaction chamber within a range of 1 Pa to 4 Pa.

[0016] According to an eighth aspect of the present invention, there is provided a dry etching method as defined in the first or fourth aspect, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 90° to 45° and an etching rate is controlled within a range of 300 nm/min to 1250 nm/min, by adjustment of (flow rate of HI/mixed gas total flow rate) of the mixed gas within a range of 10% to 30%.

[0017] According to a ninth aspect of the present invention, there is provided a dry etching method as defined in the first or fourth aspect, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 90° to 45° and an etching rate is controlled within a range of 3000 nm/min to 800 nm/min, by adjustment of a bias high-frequency power applied to the InP-based compound semiconductor substrate within a range of 200 W to 100 W.

[0018] According to a 10th aspect of the present invention, there is provided a dry etching method as defined in the first or fourth aspect, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 50° to 90° and an etching rate is controlled within a range of 0.5 μm/min to 5 μm/min by adjustment of a frequency of the high-frequency power applied to the discharge coil within a range of 13.6 MHz to 100 MHz.

[0019] According to an 11th aspect of the present invention, there is provided a dry etching method as defined in the second or fifth aspect, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 50° to 80° and an etching rate is controlled within a range of 1100 nm/min to 2000 nm/min by adjustment of a surface temperature of the InP-based compound semiconductor substrate within a range of 50° C. to 150° C.

[0020] According to a 12th aspect of the present invention, there is provided a dry etching method as defined in any one of the first to 11th aspects, wherein a frequency of the high-frequency power that is applied to the discharge coil or the antenna is a frequency in UHF band from 300 MHz to 3 GHz.

[0021] According to a 13th aspect of the present invention, there is provided a dry etching method as defined in any one of the first to 12th aspects, wherein a frequency of a bias that is applied to the substrate is not more than 13.56 MHz.

[0022] According to a 14th aspect of the present invention, there is provided a dry etching method as defined in any one of the first to 12th aspects, wherein a frequency of a bias that is applied to the substrate is any one of 13.56 MHz, 2 MHz, 800 kHz, and 500 kHz.

[0023] According to a 15th aspect of the present invention, there is provided a dry etching method as defined in any one of the first to fifth and 12th to 14th aspects, wherein the substrate is subjected to dry etching in a high-vacuum zone with a degree of vacuum between 0.1 Pa and 0.5 Pa in the reaction chamber.

[0024] According to a 16th aspect of the present invention, there is provided a dry etching method as defined in the first to fifth and 12th to 14th aspects, wherein a degree of vacuum in the reaction chamber is in a pressure zone of 0.3 Pa.

[0025] According to a 17th aspect of the present invention, there is provided a dry etching method as defined in the first aspect, wherein a frequency of the high-frequency power that is applied to the antenna is 13.56 MHz, wherein a frequency of the bias high-frequency power that is applied to the substrate is 13.56 MHz, wherein 100 μm or above deep etching fabrication in a region of the substrate on which a resin resist mask does not reside is performed with use, as the etching gas, of a gas that is selected from a group consisting of inert gas, gas containing Cl2, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to hydrogen iodide, and wherein slopes having an angle of inclination between 90 and 70 degrees are formed with etching fabrication in via holes or recesses in the region on which the resin resist mask does not reside.

[0026] According to an 18th aspect of the present invention, there is provided a dry etching method as defined in the second aspect, wherein a frequency of the high-frequency power that is applied to the discharge coil is 100 MHz; a frequency of the bias high-frequency power that is applied to the substrate is 500 kHz; 100 μm or above deep etching fabrication in a region of the substrate on which a resin resist mask does not reside is performed with use, as the etching gas, of gas that is selected from a group consisting of inert gas, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to gas containing Cl2; and slopes having an angle of inclination between 90 and 70 degrees are formed with etching fabrication in via holes or recesses in the region on which the resin resist mask does not reside.

[0027] According to a 19th aspect of the present invention, there is provided a dry etching method as defined in any one of the first to 18th aspects, wherein a surface temperatures of the substrate is in a temperature range in which resin resist can be used.

[0028] According to a 20th aspect of the present invention, there is provided a dry etching apparatus, comprising:

[0029] a reaction chamber;

[0030] a gas feeding device for feeding into the reaction chamber mixed gas that is of hydrogen iodide gas and of inert gas and that is used as etching gas;

[0031] an exhaust device for exhausting the reaction chamber;

[0032] a high-frequency power applying device for applying a 13.56 MHz or above high-frequency power to a flat spiral discharge coil that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber;

[0033] a high-frequency voltage applying device for substrate electrode for applying a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode; and

[0034] a control device that controls a pressure in the reaction chamber to a predetermined value by feeding of the mixed gas of the hydrogen iodide gas and of the inert gas into the reaction chamber by the gas feeding device and by exhausting from the reaction chamber by the exhaust device, that causes plasma to be generated in the reaction chamber by application of the 13.56 MHz or above high-frequency power to the flat spiral discharge coil by the high-frequency power applying device, and that subjects the InP-based compound semiconductor substrate to etching while controlling a density of the plasma by the high-frequency power applied to the discharge coil or antenna and while controlling ion energy that reaches the InP-based compound semiconductor substrate by application of the high-frequency voltage to the substrate electrode by the high-frequency voltage applying device for substrate electrode and the high-frequency power source for electrode with such plasma density control independent from the ion energy control.

[0035] According to a 21st aspect of the present invention, there is provided a dry etching apparatus, comprising:

[0036] a reaction chamber;

[0037] a gas feeding device for feeding into the reaction chamber mixed gas that is of gas containing chlorine or hydrogen bromide or hydrogen chloride and of inert gas and that is used as etching gas;

[0038] an exhaust device for exhausting the reaction chamber;

[0039] a high-frequency power applying device for applying a 13.56 MHz or above high-frequency power to a flat spiral discharge coil or antenna that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber;

[0040] a high-frequency voltage applying device for substrate electrode for applying a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode; and

[0041] a control device that controls a pressure in the reaction chamber to a predetermined value by feeding of the mixed gas of the gas containing chlorine or hydrogen bromide or hydrogen chloride and of the inert gas into the reaction chamber by the gas feeding device and by exhausting from the reaction chamber by the exhaust device, that causes plasma to be generated in the reaction chamber by application of the 13.56 MHz or above high-frequency power to the flat antenna by the high-frequency power applying device, and that subjects the InP-based compound semiconductor substrate to etching while controlling a density of the plasma by the high-frequency power applied to the antenna and while controlling ion energy that reaches the InP-based compound semiconductor substrate by application of the high-frequency voltage to the substrate electrode by the high-frequency voltage applying device for substrate electrode and the high-frequency power source for electrode with the plasma density control independent from the ion energy control.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] These and other aspects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which:

[0043]
FIG. 1 is a schematic illustration of a dry etching apparatus for practicing a dry etching method of a first embodiment of the present invention;

[0044]
FIG. 2 is a schematic illustration of a dry etching apparatus for practicing a dry etching method of a second embodiment of the present invention;

[0045]
FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D are views showing a relation between pressures and angles of inclination of via holes or recesses on an InP substrate below a resist mask in the dry etching apparatus for practicing the dry etching method of the first embodiment;

[0046]
FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D are views showing a relation between (flow rate of HI/total flow rate) and angles of inclination of via holes or recesses on an InP substrate below a resist mask and a relation between (flow rate of HI/total flow rate) and etching rates in the dry etching apparatus for practicing the dry etching method of the first embodiment;

[0047]
FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5D are views showing a relation between bias high-frequency powers applied to the substrate and angles of inclination of via holes or recesses on an InP substrate below a resist mask and a relation between bias high-frequency powers applied to the substrate and etching rates in the dry etching apparatus for practicing the dry etching method of the first embodiment;

[0048]
FIG. 6 is a view showing a relation between frequencies of high-frequency power applied to the discharge coil and angles of inclination of via holes or recesses on an InP substrate below a resist mask and a relation between frequencies of high-frequency power applied to the discharge coil and etching rates in the dry etching apparatus for practicing the dry etching method of the first embodiment;

[0049]
FIG. 7A and FIG. 7B are a sectional view and a perspective view as a working example in which a resin resist mask having a thickness of 80 μm has been placed on an InP substrate and in which a region of the InP substrate without the resin resist mask has been etched deeply by 140 μm, in results of dry etching by the dry etching apparatus for practicing the dry etching method of the first embodiment;

[0050]
FIG. 8 is a diagram showing a relation between surface temperatures of the substrate and angles of inclination of via holes or recesses on the InP substrate below a resist mask and a relation between surface temperatures of the substrate and etching rates in the dry etching apparatus for practicing the dry etching method of the second embodiment;

[0051]
FIG. 9A and FIG. 9B are a sectional view and a perspective view as a working example in which a heat resistant resin resist mask having a thickness of 27 μm has been placed on an InP substrate and in which a region of the InP substrate without the resin resist mask has been etched deeply by 105 μm in a shape of an inverted cone in general with a diameter of 30 μm, in results of dry etching by the dry etching apparatus for practicing the dry etching method of the second embodiment;

[0052]
FIG. 10A, FIG. 10B, FIG. 10C, and FIG. 10D are a sectional view and a perspective view as a working example in which a heat resistant resin resist mask having a thickness of 27 μm has been placed on an InP substrate and in which a region of the InP substrate without the resin resist mask has been etched deeply by 110 μm in a generally column shape with a diameter of 70 μm, and a sectional view and a perspective view in which the region has been etched deeply by 100 μm in a generally column shape with a diameter of 30 μm, in results of dry etching by the dry etching apparatus for practicing the dry etching method of the second embodiment; and

[0053]
FIG. 11 is a diagram showing relations between high-frequency power applied to the discharge coil and angles of inclination of via holes or recesses on an InP substrate below a resist mask in the dry etching apparatus for practicing the dry etching methods of the first and second embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings.

[0055] Hereinbelow, embodiments of the present invention will now be described in detail with reference to the drawings.

[0056] As a dry etching apparatus for practicing a dry etching method of a first embodiment of the present invention is used an apparatus shown in FIG. 1. In FIG. 1, predetermined gas is introduced into a vacuum chamber 1 as an example of a reaction chamber from a gas feeding device 2 and exhaust of the reaction chamber is performed by a pump 3 as an example of an exhaust device so that inside of the vacuum chamber 1 is held under a predetermined pressure, a multi-spiral coil (a flat spiral discharge coil) 5 on a dielectric plate 12 of quartz or the like is supplied with predetermined high-frequency power (e.g., with a frequency of 13.56 MHz) by a high-frequency power source 4 for discharge coil, and plasma is then produced in the vacuum chamber 1, so that plasma treatment, e.g., dry etching, deposition, surface reforming or the like can be executed on a substrate (a wafer) 7 of InP-based compound semiconductor put on a substrate electrode 6. In this first embodiment, plasma treatment is executed for etching treatment. In this case, ion energy that reaches the substrate 7 can be controlled by supply of high-frequency power to the substrate electrode 6 from a high-frequency power source 8 for substrate electrode. Thus high-density plasma is produced, the substrate 7 is provided with a bias potential, and a density of the plasma and the bias potential are independently controlled. In FIG. 1 is shown an example in which a multi-spiral coil is used as the flat spiral discharge coil 5. In the discharge coil 5, four spiral discharge coils are united at center positions thereof and are spaced at uniform intervals circumferentially, the center positions are connected to the high-frequency power source 4, and outer peripheral ends thereof are grounded respectively.

[0057] As the gas that is introduced into the vacuum chamber 1 from the gas feeding device 2, in other words, as etching gas may be used gas that is selected from five types of gas of inert gas, gas containing Cl2, gas containing BCl3, gas containing HBr, and gas containing HCl in addition to hydrogen iodide gas, i.e., mixed gas of hydrogen iodide gas and inert gas, mixed gas of hydrogen iodide gas and gas containing Cl2, mixed gas of hydrogen iodide gas and gas containing BCl3, mixed gas of hydrogen iodide gas and gas containing HBr, or mixed gas of hydrogen iodide gas and gas containing HCl. Appropriate selection of type of these gases makes it possible to form a fabrication shape that is to be formed by etching, for example, an angle of inclination of slopes (sloping surfaces) 7b (an angle θ the slopes 7b of the substrate 7 form with a plane parallel to a surface of the substrate) in formation of via holes or recesses 7a at a desired angle in a region of the substrate 7 on which no resin resist mask 30 resides. In process of the etching treatment, change of type of the gas makes it possible to change the angle θ of inclination of the via hole or recess 7a that is formed by etching in the region of the substrate 7 on which no resin resist mask 30 resides. For example, deep etching may initially be performed in a direction orthogonal to the surface of the substrate 7, then different gas may be introduced in vicinity of a bottom section, and slopes inclined gently relative to the orthogonal direction may be formed at corners of the bottom section. With appropriate selection of types of the gases in process of the etching treatment, surfaces orthogonal to the surface of the substrate 7 and slopes having various angles of inclination can be combined arbitrarily in the region of the surface of the substrate 7 on which no resin resist mask 30 resides and a desired fabrication shape can thereby be formed.

[0058] As high-frequency power that is applied by the high-frequency power source 4 for discharge coil as the high-density plasma source may be applied frequencies not lower than 13.56 MHz, to be more specific, frequencies of 13.56 MHz, 27.12 MHz, 40.68 MHz, 60 MHz, 80 MHz, 100 MHz, or UHF frequencies from 300 MHz to 3 GHz. Practically, 13.56 MHz is most preferable for the dry etching method and apparatus according to the first embodiment.

[0059] On the other hand, a bias voltage with a frequency not higher than 13.56 MHz may be applied to the substrate electrode 6 by the high-frequency power source 8 for substrate electrode. To be more specific, 13.56 MHz, 2 MHz, 800 kHz, and 500 kHz may be used as the frequency of the bias that is applied to the substrate electrode 6. Among those, practically, 500 kHz that can maximize etching rate is preferable for the dry etching method and apparatus according to the first embodiment.

[0060] The substrate 7 is subjected to dry etching in a high-vacuum zone with a degree of vacuum between 0.1 Pa and 0.5 Pa or less in the reaction chamber 1. More specifically, a pressure zone with a degree of vacuum of 0.3 Pa is preferable in the reaction chamber 1 with 100 MHz and 500 kHz.

[0061] The etching treatment may basically be performed at ordinary temperatures. The plasma treatment, however, can be performed more quickly than at ordinary temperatures, on condition that the substrate electrode 6 is heated so that the substrate 7 has a surface temperature, e.g., it a range of from 200° C. to 250° C.

[0062] In a specific example, a frequency of the high-frequency power that is applied to the discharge coil is VHF 100 MHz, a frequency of the bias high-frequency power that is applied to the substrate is 500 kHz and, for or example, slopes 7b having an angle of inclination of 70 degrees can be formed with etching fabrication in via holes or recesses 7a in a region on which a resin resist mask 30 having a thickness of 40 μm does not reside, on condition that mixed gas of gas containing chlorine and of inert gas is used as etching gas. In another example, a frequency of the high-frequency power that is applied to the discharge coil is between 13.56 MHz and 100 MHz, a frequency of the bias high-frequency power that is applied to the substrate is 13.56 MHz and, for example, slopes 7b having an angle of inclination between 50 and 90 degrees can be formed with etching fabrication in via holes or recesses 7a in a region on which a resin resist mask 30 does not reside, on condition that mixed gas of hydrogen iodide gas and of inert gas is used as etching gas. In both cases, 100 μm or above deep etching fabrication can be performed at an etching rate of at least 1000 nm/min or larger.

[0063] Conventionally, by contrast, deep etching fabrication can be executed by no more than 50 μm, and etching rates no more than below 1 μm/min (e.g., on the order of 0.05 to 0.7 μm/min) can be achieved even with heating up to vicinity of 200° C., so that it takes one hour and a half to execute 50 μm deep etching fabrication.

[0064] InP-based compound semiconductor substrates produced with the etching method may be applied to optodevices, devices for laser, electronic devices, and the like, and more specific examples of the application include devices for high-speed radio communication.

[0065] In accordance with the first embodiment, high-frequency power of 13.56 MHz or higher is applied to the flat spiral discharge coil 5, a high-frequency voltage is applied to the substrate electrode 6 by the high-frequency power source 8 for electrode, both are independently controlled, etching gas is appropriately selected, and thus 20 μm or above deep etching fabrication that has practically been unachievable in conventional RIE plasma treatment and, more preferably, 100 μm or above deep etching fabrication can rapidly be performed for the InP-based compound semiconductor substrate 7. In conventional RIE plasma treatment, that is to say, the upper electrode is grounded, high-frequency power of 13.56 MHz is applied to the substrate, and an etching rate is increased to vicinity of 10 nm/min by the treatment at a high temperature of 250° C. with mixed gas of CH4 and H2; however, 10 nm/min is too low for deep etching fabrication and makes practically impossible the deep etching fabrication by 20 μm or above, more preferably, by 100 μm or above. In the first embodiment, by contrast, an etching rate can be increased to several tens or several hundreds of times the conventional rate (for example, to 1000 nm/min).

[0066] Control of operations of the devices 2, 3, 4, 8, and the like in the dry etching apparatus in accordance with the first embodiment is constituted so as to be executed automatically by a control device 1000. On condition that pertinent information illustrated in FIG. 3 through FIG. 6 has been stored in a memory 1001 of the control device 1000 in advance, accordingly, an operator is capable of making the apparatus execute dry etching, for example, at a desired angle of inclination or a desired etching rate on basis of the pertinent information, in control of the angle θ of inclination and the like under various conditions that will be described later.

[0067] High temperatures on the order of 250° C. for increase in rate of treatment require 20 μm SiO2 as a mask to be formed on a surface of an InP-based compound semiconductor substrate in an additional CVD process, because a resistible temperature of a resist mask placed on the surface of the substrate and made of resin is as low as on the order of 120 to 130° C. Thus the additional CVD process is conventionally required. By contrast, the first embodiment is practicable even in a temperature range such as ordinary temperature in which resin resist can be used, therefore allows a resist mask 30 made of resin to be adequately used, avoids necessity to form an SiO2 mask by the CVD process and thus avoids necessity of the additional CVD process.

[0068] In accordance with the above method, mirror finish of the surface of the substrate 7 can be achieved and thus a damageless method can be attained.

[0069] In accordance with the above method, switches of etching gas to gas of different type in process of the etching treatment make it possible to change angle θ of inclination of the via hole or recess 7a that is formed on the substrate 7 and then make it possible to control fabrication shape into a desired shape.

[0070] Hereinbelow, working examples of the dry etching apparatus and method of the first embodiment will be described.

[0071] In an example, a frequency of the high-frequency power that is applied to the discharge coil is 13.56 MHz, a frequency of the bias high-frequency power that is applied to the substrate is 13.56 MHz, gas that is selected from five types of gas of inert gas, gas containing Cl2, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to hydrogen iodide (HCl) is used as etching gas, 100 μm or above deep etching fabrication is thus performed at 140° C. or lower in a region of the substrate on which a resin resist mask does not reside, and slopes having an angle of inclination between 90 and 70 degrees are formed with etching fabrication in via holes or recesses in the region on which the resin resist mask does not reside. An etching rate in this process is not larger than 2 μm/min. Hydrogen iodide (HCl) is used because fabricability on InP (in other words, fabricability in terms of etching rate, shape control, and condition of fabricated surface) is thereby improved greatly. Fabrication can be performed at low temperatures not higher than 140° C. (e.g., 100° C. to 150° C.), resin resist masks having resistible temperatures from 140° C. to 150° C. can therefore be used instead of expensive masks made of metal, cost of masks is reduced, and mass production is facilitated.

[0072] In the dry etching apparatus of the first embodiment, as shown in FIG. 3D for example, where high-frequency power applied to the discharge coil is from 700 to 900 W, where bias high-frequency power applied to the substrate is from 100 to 150 W, and where flow rates of mixed gas HI/He are 30/120 SCCM, an angle of inclination of via holes or recesses on an InP substrate below a resist mask changes from 90° (a point A in FIG. 3D: see FIG. 3A) through 70° (a point B in FIG. 3D: see FIG. 3B) to 60° (a point C in FIG. 3D: see FIG. 3C) as a degree of vacuum in the reaction chamber 1 changes from 1 Pa (the point A in FIG. 3D: see FIG. 3A) through 3 Pa (the point B in FIG. 3D: see FIG. 3B) to 4 Pa (the point C in FIG. 3D: see FIG. 3C).

[0073] Accordingly, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask can be controlled within the range of 90° to 60° by adjustment of a degree of vacuum in the reaction chamber 1 within a range of 1 Pa to 4 Pa.

[0074] In the dry etching apparatus of the first embodiment, as shown in FIG. 4D, where high-frequency power applied to the discharge coil is from 700 to 900 W, where bias high-frequency power applied to the substrate is from 100 to 150 W, and where a degree of vacuum in the reaction chamber 1 is 2 Pa, an angle θ of inclination of via holes or recesses on an InP substrate below a resist mask changes from 90° (a point D in FIG. 4D: see FIG. 4A) through 80° (a point E in FIG. 4D: see FIG. 4B) to 45° (a point F in FIG. 4D: see FIG. 4C) as (flow rate of HI/total flow rate) (%) of the mixed gas (where total flow rate is flow rate of HI plus flow rate of He) changes from 10% (the point D in FIG. 4D: see FIG. 4A) through 20% (the point E in FIG. 4D: see FIG. 4B) to 30% (the point F in FIG. 4D: see FIG. 4C). On the same condition, an etching rate changes from 300 nm/min (the point D in FIG. 4D: see FIG. 4A) through 600 nm/min (the point E in FIG. 4D: see FIG. 4B) to 1250 nm/min (the point F in FIG. 4D: see FIG. 4C) as (flow rate of HI/total flow rate) (%) of the mixed gas (where total flow rate is flow rate of HI plus flow rate of He) changes from 10% (the point D in FIG. 4D: see FIG. 4A) through 20% (the point E in FIG. 4D: see FIG. 4B) to 30% (the point F in FIG. 4D: see FIG. 4C).

[0075] Accordingly, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask can be controlled within the range of 90° to 45° by adjustment of (flow rate of HI/total flow rate) of the mixed gas within the range of 10% to 30%. Besides, the etching rate can be controlled within a range of 300 nm/min to 1250 nm/min by adjustment of (flow rate of HI/total flow rate) of the mixed gas within a range of 10% to 30%.

[0076] In the dry etching apparatus of the first embodiment, as shown in FIG. 5D, where a high-frequency power applied to the discharge coil is from 700 to 900 W, where flow rates of mixed gas HI/He are 30/120 SCCM, and where a degree of vacuum in the reaction chamber 1 is 2 Pa, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask changes from 90° (a point H in FIG. 5D: see FIG. 5A) through 65° (a point I in FIG. 5D: see FIG. 5B) to 45° (a point J in FIG. 5D: see FIG. 5C) as a bias high-frequency power applied to the substrate changes from 200 W (the point H in FIG. 5D: see FIG. 5A) through 150 W (the point I in FIG. 5D: see FIG. 5B) to 100 W (the point J in FIG. 5D: see FIG. 5C). On the same condition, an etching rate changes from 3000 nm/min (the point H in FIG. 5D: see FIG. 5A) through 1600 nm/min (the point I in FIG. 5D: see FIG. 5B) to 800 nm/min (the point J in FIG. 5D: see FIG. 5C) as a bias high-frequency power applied to the substrate changes from 200 W (the point H in FIG. 5D: see FIG. 5A) through 150 W (the point I in FIG. 5D: see FIG. 5B) to 100 W (the point J in FIG. 5D: see FIG. 5C)

[0077] Accordingly, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask can be controlled within a range of 90° to 45° by adjustment of the bias high-frequency power applied to the substrate within a range of 200 W to 100 W. Besides, the etching rate can be controlled within a range of 3000 nm/min to 800 nm/min by adjustment of the bias high-frequency power applied to the substrate within a range of 200 W to 100 W.

[0078] In the dry etching apparatus of the first embodiment, as shown in FIG. 6, where, the bias high-frequency power applied to the substrate is from 100 to 150 W, where the flow rates of the mixed gas HI/He are 30/120 SCCM, and where the degree of vacuum in the reaction chamber 1 is 2 Pa, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask changes from 50 through 50°, 68°, and 80° to 90° as the frequency of high-frequency power applied to the discharge coil changes from 13.6 MHz through 27.1 MHz, 40.7 MHz, and 60 MHz to 100 MHz. On the same condition, the etching rate changes from 0.5 μm/min through 1.3 μm/min, 2.2 μm/min, and 4 μm/min to 5 μm/min as the frequency of high-frequency power applied to the discharge coil changes from 13.6 MHz through 27.1 MHz, 40.7 MHz, and 60 MHz to 100 MHz.

[0079] Accordingly, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask can be controlled within a range of 50° to 90° by adjustment of the frequency of high-frequency power applied to the discharge coil within a range of 13.6 MHz to 100 MHz. Besides, the etching rate can be controlled within a range of 0.5 μm/min to 5 μm/min by adjustment of the frequency of high-frequency power applied to the discharge coil within a range of 13.6 MHz to 100 MHz.

[0080] In FIG. 7A and FIG. 7B are shown a sectional view and a perspective view as a working example in which a resin resist mask having a thickness of 80 μm has been placed on an InP substrate and in which a region of the InP substrate without the resin resist mask has been etched deeply by 140 μm. An etching rate in this process is 1.4 μm/min, mixed gas is of HI/He, a surface temperature of the substrate is 100° C., and a selection ratio is 5.

[0081] The present invention is not limited to the above embodiment but may be implemented in other various aspects.

[0082] In a dry etching apparatus for practicing a dry etching method of a second embodiment of the present invention, an antenna may be used in place of the discharge coil, for example, depending on the conditions concerning etching (e.g., on condition that a frequency of the high-frequency power applied to the discharge coil is 100 MHz). FIG. 2 is a sectional view of a plate-like antenna type plasma treatment apparatus. In FIG. 2, predetermined gas is introduced into a vacuum chamber 1 as an example of a reaction chamber from a gas feeding device 2 and exhaust of the reaction chamber is performed by a pump 3 as an example of an exhaust device so that inside of the vacuum chamber 1 is held under a predetermined pressure, a predetermined high-frequency power (e.g., with a frequency of 100 MHz) is supplied to an antenna 15, by a high-frequency power source 4 for antenna, through a through hole 17 provided in a dielectric plate 16 that is interposed between the antenna 15 and the vacuum chamber 1 and that is generally equal in outside dimensions to the antenna 15, and plasma is then produced in the vacuum chamber 1, so that plasma treatment such as dry etching, deposition, or surface reforming can be executed on a substrate 7 of InP-based compound semiconductor put on a substrate electrode 6. In this second embodiment, plasma treatment is executed for etching treatment. In this case, ion energy that reaches the substrate 7 can be controlled by supply of high-frequency power to the substrate electrode 6 from a high-frequency power source 8 for substrate electrode. A surface of the antenna 15 is covered with an insulation cover 11. A plasma trap 14 is provided that is composed of a grooved space between the dielectric plate 16 and a dielectric ring 12 provided around the dielectric plate 16 and of a grooved space between the antenna 15 and a conducting ring 13 provided around the antenna 15. With such a constitution, electromagnetic waves emitted from the antenna 5 are intensified by the plasma trap 14, and high-density plasma (hollow cathode discharge) is apt to be generated in the plasma trap 14 surrounded with solid surfaces because low-electron-temperature plasma tends to cause hollow cathode discharge. Accordingly, a plasma density in the plasma trap 14 is highest in the vacuum chamber 1 and transportation of plasma to vicinity of, the substrate 7 with diffusion provides more uniform plasma. Practically, 100 MHz is most preferable for the dry etching apparatus and method of the second embodiment.

[0083] Control of operations of the devices 2, 3, 4, 8, and the like in the dry etching apparatus in accordance with the second embodiment is constituted so as to be executed automatically by a control device 1000. On condition that pertinent information illustrated in FIG. 8 has been stored in a memory 1001 of the control device 1000 in advance, accordingly, an operator is capable of making the apparatus execute dry etching, for example, at a desired angle of inclination or a desired etching rate on basis of the pertinent information, in control of the angle of inclination and the like under various conditions that will be described later.

[0084] Hereinbelow, working examples of the dry etching apparatus and method of the second embodiment will be described.

[0085] In an example, a frequency of the high-frequency power that is applied to the antenna is from 27.12 to 100 MHz, a frequency of a bias high-frequency power that is applied to the substrate is 500 kHz, gas that is selected from four types of gas of inert gas, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to gas containing Cl2 is used as etching gas, 100 μm or above deep etching fabrication is thus performed at 150 to 200° C. in a region of the substrate on which the resin resist mask does not reside, and slopes having an angle of inclination between 90 and 70 degrees are formed with etching fabrication in via holes or recesses in the region on which the resin resist mask does not reside. An etching rate in this process is not larger than 5 μm/min, a selection ratio (etching of InP/etching of mask) is not less than 10, and such a high etching rate and a high selection ratio can be achieved. With use of 100 MHz as the frequency of the high-frequency power, the selection ratio is improved (for example, can be made larger than 10 though has conventionally been able to be increased so as to be no more than on the order of 3 or 4) and the etching rate can be increased (for example, can be increased to 5 μm/min though has been less than 1 μm/min at maximum). In another example of the dry etching apparatus and method of the second embodiment, a degree of vacuum in the reaction chamber is not higher than 0.5 Pa and is preferably 0.3 Pa, a frequency of the high-frequency power that is applied to the antenna is 100 MHz (900 W or less), a frequency of a bias high-frequency power that is applied to the substrate is 500 kHz (400 W or less), gas that is selected from four types of gas of inert gas, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to gas containing Cl2 is used as etching gas, a surface temperature of the substrate. is, for example, 150° C. or lower and is preferably 80° C. or lower (with a selection ratio not smaller than about 2), and the selection ratio is not smaller than about 5 and is preferably not smaller than 10.

[0086] In the working examples of the dry etching apparatus and method of the second embodiment, as shown in FIG. 8, where a high-frequency power applied to the antenna is from 500 to 900 W, where a bias high-frequency power applied to the substrate is from 300 to 400 W, where flow rates of mixed gas Cl2/Ar are 30/30 SCCM, and where a degree of vacuum in the reaction chamber 1 is 0.3 Pa, an angle θ of inclination of via holes or recesses on an InP substrate below a resist mask changes from 50° through 65° to 80° as a surface temperature of the substrate changes from 50° C. through 100° C. to 150° C. On the same condition, an etching rate also changes from 1100 nm/min through 1500 nm/min to 2000 nm/min as the surface temperature of the substrate changes from 50° C. through 100° C. to 150° C.

[0087] Accordingly, an angle θ of inclination of via holes or recesses on an InP substrate below a resist mask can be controlled within a range of 50° to 80° by adjustment of the surface temperature of the substrate within a range of 50° C. to 150° C. Besides, the etching rate can be controlled within a range of 1100 nm/min to 2000 nm/min by adjustment of the surface temperature of the substrate within a range of 50° C. to 150° C.

[0088] In FIG. 9A and FIG. 9B are shown a sectional view and a perspective view as a working example in which a heat resistant resin resist mask having a thickness of 27 μm has been placed on an InP substrate and in which a region of the InP substrate without the resin resist mask has been etched deeply by 105 μm in a shape of an inverted cone in general with a diameter of 30 μm. An etching rate in this process is 1.6 μm/min, mixed gas is Cl2/Ar, a surface temperature of the substrate is 100° C., and a selection ratio is 6.

[0089] In FIG. 10A, FIG. 10B, FIG. 10C, and FIG. 10D, as working examples, are shown a sectional view and a perspective view in which a heat resistant resin resist mask having a thickness of 27 μm has been placed on an InP substrate and in which a region of the InP substrate without the resin resist mask has been etched deeply by 110 μm in a generally column shape with a diameter of 70 μm, and a sectional view and a perspective view in which the region has been etched deeply by 100 μm in a generally column shape with a diameter of 30 μm. Etching rates in these processes are 4.5 μm/min and 4 μm/min, mixed gas are Cl2/Ar and Cl2/Ar, surface temperatures of the substrate are 150° C. and 150° C., and selection ratios are not less than 10 and not less than 10, respectively.

[0090] Among examples of the InP-based compound semiconductor substrates in the embodiments are compound semiconductor substrates of InGaAsP, InGaP, InAsP, and the like. The thicknesses of the resin resist masks that are placed on the substrates in the embodiments are required to be at least 10 μm and, on condition that the selection ratio is 10, use of a resin resist mask having a thickness of 10 μm allows deep etching of up to 100 μm to be performed.

[0091] To be brief, the dry etching apparatus and method of the first embodiment make possible a dry etching treatment at temperatures not higher than 140° C. that allow use of inexpensive resin resist masks suitable for mass production, eliminate necessity for use of expensive masks made of metal, and achieve dry etching treatment of the InP-based compound semiconductor substrates with satisfactory fabricability, with use of mixed gas of hydrogen iodide gas and of inert gas as the etching gas.

[0092] By contrast, the dry etching apparatus and method of the second embodiment are most suitable for high-speed dry etching treatment and achieve a high selection ratio. Besides, plasma temperature can be decreased, damage to a resist can be decreased, and a selection ratio on the resist can be increased (for example, can be increased to 5 or larger), in comparison with those of the dry etching apparatus and method of the first embodiment (the selection ratio has conventionally been able to be increased to no more than about 1, even with heating to vicinity of 200° C.). The second embodiment is therefore suitable for 100 μm or above deep etching fabrication. As a result of the high selection ratio on resist, 100 μm or above deep etching fabrication can be performed even if a thickness of the resist film is small (for example, on the order of 10 to 20 μm). By the use of the high selection ratio, therefore, 200 μm or above deep etching fabrication can be performed with a diameter of 30 μm or larger.

[0093] In the dry etching apparatus of the first and second embodiments, as shown in FIG. 11, where the bias high-frequency power applied to the substrate is from 100 to 200 W, where the flow rates of the mixed gas HI/He are 30/120 SCCM and the flow rates of the Cl2/Ar are 40/30 SCCM, where the degree of vacuum in the reaction chamber 1 is not more than 3 Pa, and where the frequencies of the high-frequency power applied to the discharge coil or the antenna are 13.6 MHz and 100 MHz, the angles e of inclination of the via holes or recesses on the InP substrate below the resist mask change from 75° through 80° to 90°, or from 70° through 73° to 80° as high-frequency power applied to the discharge coil or the antenna changes from 300 W through 600 W to 900 W.

[0094] Accordingly, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask can be controlled within a range of 75° through 80° to 90° by adjustment of the high-frequency power applied to the discharge coil within a range of 300 through 600 to 900 W on condition that the frequency of the high-frequency power applied to the discharge coil is 13.6 MHz. Besides, the angle θ of inclination of the via holes or recesses on the InP substrate below the resist mask can be controlled within a range of 70° through 73° to 60° by adjustment of the high-frequency power applied to the antenna within a range of 300 through 600 to 900 W on condition that the frequency of the high-frequency power applied to the antenna is 100 MHz.

[0095] With an appropriate combination of arbitrary embodiments among the various embodiments, effects thereof can be achieved.

[0096] In accordance with the present invention, the 13.56 MHz or above high-frequency power is applied to the flat spiral discharge coil or antenna, the high-frequency voltage is applied to the substrate electrode by the high-frequency power source for electrode, both are independently controlled, the etching gas is appropriately selected, and thus 20 μm or above deep etching fabrication that has practically been unachievable in conventional RIE plasma treatment and, more preferably, 100 μm or deeper fabrication can rapidly be performed on an InP-based compound semiconductor substrate. In conventional RIE plasma treatment, that is to say, an upper electrode is grounded, a 13.56 MHz high-frequency power is applied to a substrate, and an etching rate is increased to vicinity of 10 nm/min by treatment at a high temperature of 250° C. with a mixed gas of CH4 and H2; however, 10 nm/min is too low for deep etching fabrication and makes practically impossible the 20 μm or above, more preferably, 100 μm or above deep etching fabrication. In the present invention, by contrast, an etching rate can be increased to several tens or several hundreds of times the conventional rate (for example, to 1000 nm/min).

[0097] High temperatures on the order of 250° C. for increase in rate of treatment require 20 μM SiO2 as a mask to be formed on a surface of an InP-based compound semiconductor substrate in an additional CVD process because a resistible temperature of a resist mask placed on the surface of the substrate and made of resin is as low as on the order of 120 to 130° C. Thus the additional CVD process is conventionally required. By contrast, the present invention is practicable in temperatures not higher than 140° C., for example, in ordinary temperatures, therefore allows a resist mask made of resin to be adequately used, avoids necessity to form the SiO2 mask by the CVD process and thus avoids necessity of the additional CVD process.

[0098] In accordance with the present invention, mirror finish of surfaces of substrates can be achieved and thus a damageless feature can be attained.

[0099] In accordance with the present invention, switches of etching gas to gas of different type in process of etching treatment make it possible to change an angle of inclination of via holes or recesses that are formed on a substrate and make it possible to control fabrication shape into a desired shape.

[0100] Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

Claims

1. A dry etching method in which etching gas is fed into a reaction chamber and exhaust of the reaction chamber is performed so that inside of the reaction chamber is controlled to be under a predetermined pressure, in which plasma is then generated in the reaction chamber by application of a 13.56 MHz or above high-frequency power to a flat spiral discharge coil that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber, in which the InP-based compound semiconductor substrate is etched while a density of the plasma is controlled by the high-frequency power applied to the discharge coil and while ion energy that reaches the InP-based compound semiconductor substrate is is controlled by application of a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode with such ion energy control independent from the plasma density control, and in which mixed gas of hydrogen iodide gas and of inert gas is used as the etching gas.
2. A dry etching method in which etching gas is fed into a reaction chamber and exhaust of the reaction chamber is performed so that inside of the reaction chamber is controlled to be under a predetermined pressure, in which plasma is then generated in the reaction chamber by application of a 13.56 MHz or above high-frequency power to a flat antenna that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber, in which the InP-based compound semiconductor substrate is etched while a density of the plasma is controlled by the high-frequency power applied to the antenna and while ion energy that reaches the InP-based compound semiconductor substrate is controlled by application of a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode with such ion energy control independent from the plasma density control, and in which mixed gas of gas containing chlorine or hydrogen bromide or hydrogen chloride and of inert gas is used as the etching gas.
3. A dry etching method as claimed in claim 1, wherein an angle of inclination of via holes or recesses that are formed on the InP-based compound semiconductor substrate by etching is changed with use of different types of gas as the etching gas.
4. A dry etching method as claimed in claim 1, wherein an angle of inclination of via holes or recesses that are formed on the substrate by etching is changed with use, as the etching gas, of a gas that is selected from a group consisting of inert gas, gas containing Cl2, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to hydrogen iodide gas.
5. A dry etching method as claimed in claim 2, wherein an angle of inclination of via holes or recesses that are formed on the substrate by etching is changed with use, as the etching gas, of a gas that is selected from a group consisting of inert gas, gas containing BC13, gas containing HBr, and gas containing HCl with the selected gas added to gas containing Cl2.
6. A dry etching method as claimed in claim 1, wherein a frequency of the high-frequency power that is applied to the discharge coil or the antenna is any one of 27.12 MHz, 40.68 MHz, 60 MHz, 80 MHz, and 100 MHz.
7. A dry etching method as claimed in claim 1, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 90° to 60° by adjustment of a degree of vacuum in the reaction chamber within a range of 1 Pa to 4 Pa.
8. A dry etching method as claimed in claim 1, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 90° to 45° and an etching rate is controlled within a range of 300 nm/min to 1250 nm/min, by adjustment of (flow rate of HI/mixed gas total flow rate) of the mixed gas within a range of 10% to 30%.
9. A dry etching method as claimed in claim 1, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 90° to 45° and an etching rate is controlled within a range of 3000 nm/min to 800 nm/min, by adjustment of a bias high-frequency power applied to the InP-based compound semiconductor substrate within a range of 200 W to 100 W.
10. A dry etching method as claimed in claim 1, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 50° to 90° and an etching rate is controlled within a range of 0.5 μm/min to 5 μm/min by adjustment of a frequency of the high-frequency power applied to the discharge coil within a range of 13.6 MHz to 100 MHz.
11. A dry etching method as claimed in claim 2, wherein an angle of inclination of via holes or recesses on the InP-based compound semiconductor substrate below a resist mask is controlled within a range of 50° to 80° and an etching rate is controlled within a range of 1100 nm/min to 2000 nm/min by adjustment of a surface temperature of the InP-based compound semiconductor substrate within a range of 50° C. to 150° C.
12. A dry etching method as claimed in any one of claims 1 to 11, wherein a frequency of the high-frequency power that is applied to the discharge coil or the antenna is a frequency in UHF band from 300 MHz to 3 GHz.
13. A dry etching method as claimed in any one of claims 1 to 12, wherein a frequency of a bias that is applied to the substrate is not more than 13.56 MHz.
14. A dry etching method as claimed in any one of claims 1 to 12, wherein a frequency of a bias that is applied to the substrate is any one of 13.56 MHz, 2 MHz, 800 kHz, and 500 kHz.
15. A dry etching method as claimed in claim 1, wherein the substrate is subjected to dry etching in a high-vacuum zone with a degree of vacuum between 0.1 Pa and 0.5 Pa in the reaction chamber.
16. A dry etching method as claimed in claim 1, wherein a degree of vacuum in the reaction chamber is in a pressure zone of 0.3 Pa.
17. A dry etching method as claimed in claim 1, wherein a frequency of the high-frequency power that is applied to the antenna is 13.56 MHz, wherein a frequency of the bias high-frequency power that is applied to the substrate is 13.56 MHz, wherein 100 μm or above deep etching fabrication in a region of the substrate on which a resin resist mask does not reside is performed with use, as the etching gas, of a gas that is selected from a group consisting of inert gas, gas containing Cl2, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to hydrogen iodide, and wherein slopes having an angle of inclination between 90 and 70 degrees are formed with etching fabrication in via holes or recesses in the region on which the resin resist mask does not reside.
18. A dry etching method as claimed in claim 2, wherein a frequency of the high-frequency power that is applied to the discharge coil is 100 MHz; a frequency of the bias high-frequency power that is applied to the substrate is 500 kHz; 100 μm or above deep etching fabrication in a region of the substrate on which a resin resist mask does not reside is performed with use, as the etching gas, of gas that is selected from a group consisting of inert gas, gas containing BCl3, gas containing HBr, and gas containing HCl with the selected gas added to gas containing Cl2; and slopes having an angle of inclination between 90 and 70 degrees are formed with etching fabrication in via holes or recesses in the region on which the resin resist mask does not reside.
19. A dry etching method as claimed in claim 1, wherein a surface temperatures of the substrate is in a temperature range in which resin resist can be used.
20. A dry etching apparatus, comprising: a reaction chamber; a gas feeding device for feeding into the reaction chamber mixed gas that is of hydrogen iodide gas and of inert gas and that is used as etching gas; an exhaust device for exhausting the reaction chamber; a high-frequency power applying device for applying a 13.56 MHz or above high-frequency power to a flat spiral discharge coil that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber; a high-frequency voltage applying device for substrate electrode for applying a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode; and a control device that controls a pressure in the reaction chamber to a predetermined value by feeding of the mixed gas of the hydrogen iodide gas and of the inert gas into the reaction chamber by the gas feeding device and by exhausting from the reaction chamber by the exhaust device, that causes plasma to be generated in the reaction chamber by application of the 13.56 MHz or above high-frequency power to the flat spiral discharge coil by the high-frequency power applying device, and that subjects the InP-based compound semiconductor substrate to etching while controlling a density of the plasma by the high-frequency power applied to the discharge coil or antenna and while controlling ion energy that reaches the InP-based compound semiconductor substrate by application of the high-frequency voltage to the substrate electrode by the high-frequency voltage applying device for substrate electrode and the high-frequency power source for electrode with such plasma density control independent from the ion energy control.
21. A dry etching apparatus, comprising: a reaction chamber; a gas feeding device for feeding into the reaction chamber mixed gas that is of gas containing chlorine or hydrogen bromide or hydrogen chloride and of inert gas and that is used as etching gas; an exhaust device for exhausting the reaction chamber; a high-frequency power applying device for applying a 13.56 MHz or above high-frequency power to a flat spiral discharge coil or antenna that is provided so as to face an InP-based compound semiconductor substrate placed on a substrate electrode in the reaction chamber; a high-frequency voltage applying device for substrate electrode for applying a high-frequency voltage to the substrate electrode by a high-frequency power source for electrode; and a control device that controls a pressure in the reaction chamber to a predetermined value by feeding of the mixed gas of the gas containing chlorine or hydrogen bromide or hydrogen chloride and of the inert gas into the reaction chamber by the gas feeding device and by exhausting from the reaction chamber by the exhaust device, that causes plasma to be generated in the reaction chamber by application of the 13.56 MHz or above high-frequency power to the flat antenna by the high-frequency power applying device, and that subjects the InP-based compound semiconductor substrate to etching while controlling a density of the plasma by the high-frequency power applied to the antenna and while controlling ion energy that reaches the InP-based compound semiconductor substrate by application of the high-frequency voltage to the substrate electrode by the high-frequency voltage applying device for substrate electrode and the high-frequency power source for electrode with the plasma density control independent from the ion energy control.
22. A dry etching method as claimed in claim 2, wherein an angle of inclination of via holes or recesses that are formed on the InP-based compound semiconductor substrate by etching is changed with use of different types of gas as the etching gas.
23. A dry etching method as claimed in claim 2, wherein a frequency of the high-frequency power that is applied to the discharge coil or the antenna is any one of 27.12 MHz, 40.68 MHz, 60 MHz, 80 MHz, and 100 MHz.
24. A dry etching method as claimed in claim 2, wherein a frequency of the high-frequency power that is applied to the discharge coil or the antenna is a frequency in UHF band from 300 MHz to 3 GHz.
25. A dry etching method as claimed in claim 2, wherein a frequency of a bias that is applied to the substrate is not more than 13.56 MHz.
26. A dry etching method as claimed in claim 2, wherein a frequency of a bias that is applied to the substrate is any one of 13.56 MHz, 2 MHz, 800 kHz, and 500 kHz.
27. A dry etching method as claimed in claim 2, wherein the substrate is subjected to dry etching in a high-vacuum zone with a degree of vacuum between 0.1 Pa and 0.5 Pa in the reaction chamber.
28. A dry etching method as claimed in claim 2, wherein a degree of vacuum in the reaction chamber is in a pressure zone of 0.3 Pa.
29. A dry etching method as claimed in claim 2, wherein a surface temperatures of the substrate is in a temperature range in which resin resist can be used.

Priority Claims (1)

Number	Date	Country	Kind
2001-219642	Jul 2001	JP

Dry etching method and apparatus

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CPC

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Description

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Priority Claims (1)