WO2003065422A1 - High-frequency device using oxidized porous silicon layer - Google Patents

High-frequency device using oxidized porous silicon layer Download PDF

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Publication number
WO2003065422A1
WO2003065422A1 PCT/KR2003/000172 KR0300172W WO03065422A1 WO 2003065422 A1 WO2003065422 A1 WO 2003065422A1 KR 0300172 W KR0300172 W KR 0300172W WO 03065422 A1 WO03065422 A1 WO 03065422A1
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Prior art keywords
silicon substrate
layer
porous silicon
oxidized porous
silicon layer
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PCT/KR2003/000172
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French (fr)
Inventor
Choong-Mo Nam
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Telephus, Inc.
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Publication of WO2003065422A1 publication Critical patent/WO2003065422A1/en

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    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/58—Structural electrical arrangements for semiconductor devices not otherwise provided for, e.g. in combination with batteries
    • H01L23/64—Impedance arrangements
    • H01L23/647—Resistive arrangements
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/02164—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material being a silicon oxide, e.g. SiO2
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02203—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being porous
    • H—ELECTRICITY
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/02227—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process
    • H01L21/0223—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate
    • H01L21/02233—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate of the semiconductor substrate or a semiconductor layer
    • H01L21/02236—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate of the semiconductor substrate or a semiconductor layer group IV semiconductor
    • H01L21/02238—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate of the semiconductor substrate or a semiconductor layer group IV semiconductor silicon in uncombined form, i.e. pure silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/02227—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process
    • H01L21/02255—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by thermal treatment
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    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02296—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer
    • H01L21/02318—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment
    • H01L21/02362—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment formation of intermediate layers, e.g. capping layers or diffusion barriers
    • H—ELECTRICITY
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    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02524—Group 14 semiconducting materials
    • H01L21/02532—Silicon, silicon germanium, germanium
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02587—Structure
    • H—ELECTRICITY
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    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic System
    • H—ELECTRICITY
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    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/3063—Electrolytic etching
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    • H01L23/642—Capacitive arrangements
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    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/58—Structural electrical arrangements for semiconductor devices not otherwise provided for, e.g. in combination with batteries
    • H01L23/64—Impedance arrangements
    • H01L23/66—High-frequency adaptations

Definitions

  • the present invention relates to a high-frequency device using an oxidized porous silicon layer, and more particularly, to a high-frequency device using an oxidized porous silicon layer so as to prevent deterioration of the performance of a silicon substrate due to its semi-conducting characteristics.
  • a silicon substrate is inexpensive to manufacture and thus is advantageous in integrating electronic chips at a low cost compared to other compound semiconductor substrates.
  • the mobility of electrons in a silicon substrate is remarkably lower than in compound semiconductor substrates such as GaAs-based semiconductor substrates.
  • the silicon substrate has less permittivity than other compound semiconductor substrates, which would make it difficult to manufacture high-frequency transmission lines on the silicon substrate. For these reasons, the silicon substrate is not appropriate for a high-speed semiconductor device.
  • a semiconductor device that operates at a high frequency band of several GHz is formed of silicon, a signal cannot be completely transmitted or received due to the semi-conducting characteristics of silicon.
  • passive elements such as a filter, a resistor, an inductor, and a capacitor, cannot be used at high frequencies unless a thick insulating layer is present below these elements.
  • FIG. 1 is a schematic view of a conventional high-frequency device in which these passive elements are formed on a thick oxide (TO), and FIG. 2 is schematic view of another high-frequency device in which these passive elements are formed on a selective thick oxide (STO).
  • TO thick oxide
  • STO selective thick oxide
  • an oxidized porous silicon layer 16, which is the TO, and a passive element 100, such as a resistor, a capacitor, an inductor, or a filer are sequentially formed on a silicon substrate 10.
  • a passive element 100 such as a resistor, a capacitor, an inductor, or a filer
  • an insulating layer, which is positioned below the passive element 100 was used with a high-temperature silicon oxide layer made by oxygen penetrating into the silicon substrate.
  • oxygen cannot penetrate into the silicon substrate.
  • a thick oxidized porous silicon layer 16 of more than 20 ⁇ m thickness can be obtained.
  • an anodizing reaction is performed on the silicon substrate to form a porous silicon layer having fine holes.
  • This porous silicon layer is oxidized to allow oxygen to penetrate deeply into these fine holes, so that a thick silicon oxide layer can be obtained. These fine holes are filled up when the silicon oxide layer is oxidized to expand.
  • an oxidized porous silicon layer 16 which is a selective thick oxide (STO) that is selectively thickly formed, is formed in a portion of a silicon substrate 10.
  • a passive element 100 is formed on the oxidized porous silicon layer 16, and an active element 200 such as a transistor is formed on a portion of the silicon substrate 10 on which the oxidized porous silicon layer 16 is not formed.
  • STO selective thick oxide
  • the passive element 100 is formed on the oxidized porous silicon layer 16 by applying a photoresist layer directly over the silicon substrate 10 or onto a thin seed layer (not shown) formed on the silicon substrate 10, performing a photolithography process on the photoresist layer to form a photoresist pattern, performing an electroplating process or a metal deposition process on the photoresist pattern, and finally, performing a lift-off process thereon.
  • the photoresist layer must stick well to an underlying layer, so that it does not curl up at the end during photoresist patterning. However, if the photoresist layer sticks too strongly to the underlying layer, a portion of the photoresist layer may remain on a portion that it is not to be patterned after the photoresist patterning; and (ii) the photoresist layer must be formed to a uniform thickness to have a planar surface, so that the focus of light, which is irradiated during an alignment exposure process, is regular and a regular pattern can be obtained when developing the photoresist layer.
  • the above conditions cannot be satisfied.
  • the oxidized porous silicon layer 16 has an uneven surface, it is difficult for the photoresist layer to be evenly applied thereto, and further, a portion of the photoresist layer is prone to not be developed and remain on the underlying layer.
  • the buffer layer may be formed of one selected from the group consisting of Silicon Nitride, BenzoCycloButene (BCB), polyimide, Tetraethyl OrthoSilicate (TEOS)-silicon oxide, Spin-On-Glass (SOG), Undoped CVD SiO 2 (USG), BoroSilicate Glass (BSG), BoroPhosphoSilicate Glass (BPSG), and Silicon OxyNitride (SiON).
  • the passive element may be one of a resistor, an inductor, and a capacitor.
  • the oxidized porous silicon layer may be formed on the overall surface or a portion of the surface of the silicon substrate.
  • the buffer layer may be formed both on the oxidized porous silicon layer and on portions of the substrate on which the oxidized porous silicon layer is not formed. Otherwise, the buffer layer may be formed only on the oxidized porous silicon layer that is selectively formed.
  • the high-frequency device may further include an active element such as a transistor on the buffer layer formed on portions of the silicon substrate on which the oxidized silicon layer is not formed, or on portions of the silicon substrate on which the oxidized porous silicon layer and the buffer layer are not formed.
  • the high-frequency device may further include an impurity-ion implantation region or an impurity-ion diffusion region on the portions of the silicon substrate on which the oxidized porous silicon layer is not formed.
  • the oxidized porous silicon layer is formed to a thickness of at least 10 ⁇ m, more preferably, to a thickness of at least 20 ⁇ m.
  • Implanting the impurity ions may be performed by an ion implantation method or an ion diffusion method.
  • the buffer layer may be formed only on the oxidized porous silicon layer, or on the overall surface of the silicon substrate on which the oxidized porous silicon layer and the oxidized silicon layer are not formed.
  • an insulating buffer layer is formed on an irregular oxidized porous silicon layer before forming a semiconductor device, especially, a passive element, directly on the oxidized porous silicon layer. For this reason, during a subsequent process, no remnant photoresist remains, owing to the buffer layer. Therefore, it is possible to stably form a high-frequency device.
  • FIG. 1 is a schematic cross-sectional view of a passive element formed on a conventional thick oxide (TO);
  • FIGS. 3 through 7 are cross-sectional views for explaining a method of manufacturing a high-frequency element using an oxidized porous silicon layer according to a first embodiment of the present invention
  • an oxidized porous silicon layer can be thickly formed and thus it is possible to suppress deterioration in the performance of a semiconductor device due to semi-conducting characteristics of silicon.

Abstract

Provided are a high-frequency device using an oxidized porous silicon layer so as to prevent deterioration ofthe performance of a silicon substrate at high-frequency bandwidth, and a method of stably forming such a high-frequency device. The high-frequency device includes a silicon substrate, an oxidized porous silicon substrate formed on the silicon substrate, an insulating buffer layer formed on the oxidized porous silicon layer, and a passive element formed on the buffer layer. The oxidized porous silicon layer can be formed on the overall surface of the silicon substrate or selectively formed on a portion of the surface of the silicon substrate.

Description

HIGH-FREQUENCY DEVICE USING OXIDIZED POROUS
SILICON LAYER
Technical Field The present invention relates to a high-frequency device using an oxidized porous silicon layer, and more particularly, to a high-frequency device using an oxidized porous silicon layer so as to prevent deterioration of the performance of a silicon substrate due to its semi-conducting characteristics.
Background Art
Semiconductor devices have been developed to increase their integration and speed of operation. In general, a silicon substrate is inexpensive to manufacture and thus is advantageous in integrating electronic chips at a low cost compared to other compound semiconductor substrates. However, the mobility of electrons in a silicon substrate is remarkably lower than in compound semiconductor substrates such as GaAs-based semiconductor substrates. Further, the silicon substrate has less permittivity than other compound semiconductor substrates, which would make it difficult to manufacture high-frequency transmission lines on the silicon substrate. For these reasons, the silicon substrate is not appropriate for a high-speed semiconductor device.
If a semiconductor device that operates at a high frequency band of several GHz is formed of silicon, a signal cannot be completely transmitted or received due to the semi-conducting characteristics of silicon. In particular, passive elements, such as a filter, a resistor, an inductor, and a capacitor, cannot be used at high frequencies unless a thick insulating layer is present below these elements.
FIG. 1 is a schematic view of a conventional high-frequency device in which these passive elements are formed on a thick oxide (TO), and FIG. 2 is schematic view of another high-frequency device in which these passive elements are formed on a selective thick oxide (STO).
Referring to FIG. 1 , an oxidized porous silicon layer 16, which is the TO, and a passive element 100, such as a resistor, a capacitor, an inductor, or a filer are sequentially formed on a silicon substrate 10. In the past, an insulating layer, which is positioned below the passive element 100, was used with a high-temperature silicon oxide layer made by oxygen penetrating into the silicon substrate. However, in the event that the silicon oxide layer is formed to a thickness of more than 10 μm, oxygen cannot penetrate into the silicon substrate. Thus, it is not possible to obtain a thick silicon oxide layer of more than 10 μm.
To solve this problem, if the surface of the silicon substrate is processed to have porosities and then is oxidized, a thick oxidized porous silicon layer 16 of more than 20 μm thickness can be obtained. In other words, an anodizing reaction is performed on the silicon substrate to form a porous silicon layer having fine holes. This porous silicon layer is oxidized to allow oxygen to penetrate deeply into these fine holes, so that a thick silicon oxide layer can be obtained. These fine holes are filled up when the silicon oxide layer is oxidized to expand. The oxidized porous silicon layer 16, however, has an uneven surface.
Referring to FIG. 2, an oxidized porous silicon layer 16, which is a selective thick oxide (STO) that is selectively thickly formed, is formed in a portion of a silicon substrate 10. A passive element 100 is formed on the oxidized porous silicon layer 16, and an active element 200 such as a transistor is formed on a portion of the silicon substrate 10 on which the oxidized porous silicon layer 16 is not formed. As illustrated in FIGS. 1 and 2, the passive element 100 is formed on the oxidized porous silicon layer 16 by applying a photoresist layer directly over the silicon substrate 10 or onto a thin seed layer (not shown) formed on the silicon substrate 10, performing a photolithography process on the photoresist layer to form a photoresist pattern, performing an electroplating process or a metal deposition process on the photoresist pattern, and finally, performing a lift-off process thereon.
Meanwhile, when applying the photoresist layer onto the silicon substrate 10 or the seed layer, the following conditions must be satisfied:
(i) the photoresist layer must stick well to an underlying layer, so that it does not curl up at the end during photoresist patterning. However, if the photoresist layer sticks too strongly to the underlying layer, a portion of the photoresist layer may remain on a portion that it is not to be patterned after the photoresist patterning; and (ii) the photoresist layer must be formed to a uniform thickness to have a planar surface, so that the focus of light, which is irradiated during an alignment exposure process, is regular and a regular pattern can be obtained when developing the photoresist layer.
If the surface of the underlying layer on which the photoresist layer is to be formed is irregular, the above conditions cannot be satisfied. In particular, if the oxidized porous silicon layer 16 has an uneven surface, it is difficult for the photoresist layer to be evenly applied thereto, and further, a portion of the photoresist layer is prone to not be developed and remain on the underlying layer.
Disclosure of the Invention
To solve the above problems, it is a first objective of the present invention to provide a high-frequency device using an oxidized porous silicon layer so as to prevent deterioration of the performance of a silicon substrate due to the semi-conducting characteristics of silicon, and a method of manufacturing such a high-frequency device.
It is a second objective of the present invention to provide a high-frequency device using an oxidized porous silicon layer having an irregular surface on which a passive element is stably formed and no remnant photoresist remains. To accomplish one aspect of the above objectives, according to an aspect of the present invention, there is provided to provide a high-frequency device using an oxidized porous silicon layer, the high-frequency device including a silicon substrate; an oxidized porous silicon substrate formed on the silicon substrate; an insulating buffer layer formed on the oxidized porous silicon layer; and a passive element formed on the buffer layer.
The buffer layer may be formed of one selected from the group consisting of Silicon Nitride, BenzoCycloButene (BCB), polyimide, Tetraethyl OrthoSilicate (TEOS)-silicon oxide, Spin-On-Glass (SOG), Undoped CVD SiO2 (USG), BoroSilicate Glass (BSG), BoroPhosphoSilicate Glass (BPSG), and Silicon OxyNitride (SiON). Also, the passive element may be one of a resistor, an inductor, and a capacitor.
The oxidized porous silicon layer may be formed on the overall surface or a portion of the surface of the silicon substrate. The buffer layer may be formed both on the oxidized porous silicon layer and on portions of the substrate on which the oxidized porous silicon layer is not formed. Otherwise, the buffer layer may be formed only on the oxidized porous silicon layer that is selectively formed. The high-frequency device may further include an active element such as a transistor on the buffer layer formed on portions of the silicon substrate on which the oxidized silicon layer is not formed, or on portions of the silicon substrate on which the oxidized porous silicon layer and the buffer layer are not formed.
The high-frequency device may further include an impurity-ion implantation region or an impurity-ion diffusion region on the portions of the silicon substrate on which the oxidized porous silicon layer is not formed. Preferably, the oxidized porous silicon layer is formed to a thickness of at least 10 μm, more preferably, to a thickness of at least 20 μm.
To accomplish another aspect of the above objectives, there is provided a method of manufacturing a high-frequency device using an oxidized porous silicon layer, the method including forming an oxidized porous silicon layer on a silicon substrate; forming an insulating buffer layer on the oxidized porous silicon layer; and forming a passive element on the buffer layer.
Forming the oxidized porous silicon layer on the silicon substrate may include forming an aluminum electrode at the bottom of the silicon substrate; forming porosities on the surface of the silicon substrate by anodizing the silicon substrate; removing the aluminum electrode; and forming an oxidized porous silicon layer by oxidizing the surface of the porous silicon substrate.
Alternatively, forming the oxidized porous silicon layer on the silicon substrate may include forming an aluminum electrode at the bottom of the silicon substrate; selectively forming mask patterns over the silicon substrate for exposing the surface of the silicon substrate; forming porosities on the surface of the silicon substrate having the mask patterns by anodizing the silicon substrate; removing the mask patterns and the aluminum electrode; and forming an oxidized porous silicon layer by oxidizing the surface of the porous silicon substrate.
The mask patterns may be photoresist patterns or silicon nitride patterns.
Forming the oxidized porous silicon layer on the silicon substrate may include selectively forming mask patterns on the silicon substrate for exposing the surface of the silicon substrate; inducing impurity ions into the exposed silicon substrate defined by the mask patterns; removing the mask patterns; forming an aluminum electrode at the bottom of the silicon substrate; forming porosities on the surface of the silicon substrate into which the impurity ions are not induced by anodizing the silicon substrate; removing the aluminum electrode; and forming an oxidized porous silicon layer by oxidizing the surface of the porous silicon substrate.
Implanting the impurity ions may be performed by an ion implantation method or an ion diffusion method. The buffer layer may be formed only on the oxidized porous silicon layer, or on the overall surface of the silicon substrate on which the oxidized porous silicon layer and the oxidized silicon layer are not formed.
According to the present invention, an insulating buffer layer is formed on an irregular oxidized porous silicon layer before forming a semiconductor device, especially, a passive element, directly on the oxidized porous silicon layer. For this reason, during a subsequent process, no remnant photoresist remains, owing to the buffer layer. Therefore, it is possible to stably form a high-frequency device.
Brief Description of the Drawings
The above objectives and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:
FIG. 1 is a schematic cross-sectional view of a passive element formed on a conventional thick oxide (TO);
FIG. 2 is a schematic cross-sectional view of a passive element and an active element formed on a conventional selective thick oxide (STO);
FIGS. 3 through 7 are cross-sectional views for explaining a method of manufacturing a high-frequency element using an oxidized porous silicon layer according to a first embodiment of the present invention;
FIGS. 8 through 12A are cross-sectional views for explaining a method of manufacturing a high-frequency device using an oxidized porous silicon layer according to a second embodiment of the present invention; FIG. 12B is a cross-sectional view of a high-frequency device using an oxidized porous silicon layer according to a third embodiment of the present invention;
FIGS. 13 through 17A are cross-sectional views for explaining a method of manufacturing a high-frequency device using an oxidized porous silicon layer according to a fourth embodiment of the present invention; and
FIG. 17B is a cross-sectional view of a high-frequency device using an oxidized porous silicon layer according to a fifth embodiment of the present invention.
Best mode for carrying out the Invention
The present invention now will be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thickness of layers and regions are exaggerated for clarity. It will also be understood that when a layer is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. The same reference numerals in different drawings represent the same element, and thus their description will be omitted.
<First Embodiment FIGS. 3 through 7 are cross-sectional views for explaining a first embodiment of a method of manufacturing a high-frequency device using an oxidized porous silicon layer according to the present invention.
Referring to FIG. 3, a silicon substrate 10 is prepared, and an aluminum electrode 14 is formed to a thickness of about a 1000 A at the bottom of the silicon substrate 10.
Then, as shown in FIG. 4, the silicon substrate 10 having the aluminum electrode 14 at its bottom is placed in an anodizing reactor and then an anodizing reaction is performed thereon. As a result, a thick porous silicon layer 12 having a plurality of fine holes is formed to a thickness of more than 10 μm, more preferably, 20 or more μm, on the silicon substrate 10. In detail, anodizing is performed by attaching the aluminum electrode 14 formed at the bottom of the silicon substrate 10 to platinum electrode in a reaction electrolyte solution of hydrofluoric acid (HF) and ethanol that are contained in a Teflon anodizing reactor, and then applying bias voltage to the aluminum electrode 14. As a result, porosities are formed in the surface of the silicon substrate 10 at a rate of 1 μm/min.
Next, referring to FIG. 5, after the aluminum electrode 14 is removed using HF and deionized water, the porous silicon layer 12 is oxidized to form an oxidized porous silicon layer 16. This oxidization of the porous silicon layer 12 may be performed by a two-step process. First, the porous silicon layer 12 is pre-oxidized to a thickness of 700 - 800 A at a low temperature and then is oxidized to a thickness of more than 20 μm at a high temperature. In general, in the case that a high-temperature silicon oxide layer is formed by allowing oxygen to penetrate into the surface of a silicon substrate, oxygen generally cannot penetrate more than 10 μm into the silicon substrate. Thus, the silicon oxide layer cannot be formed to a thickness of more than 10μm. However, according to the present invention, since anodizing enables oxygen to penetrate deeply into the surface of the silicon substrate 10 via holes formed on the porous silicon layer 12, it is possible to form a relatively thick oxidized porous silicon layer 12. The holes of the porous silicon layer 12 are filled up when the porous silicon layer 12 is oxidized and its volume expands.
Thereafter, referring to FIG. 6, an insulating buffer layer 18 is formed over the silicon substrate 10 having the oxidized porous silicon layer 16. The buffer layer 18 is formed of Silicon Nitride, BenzoCycloButene (BCB), polyimide, Tetraethyl OrthoSilicate (TEOS)-silicon oxide, Spin-On-Glass (SOG), Undoped CVD SiO2 (USG), BoroSilicate Glass (BSG), BoroPhosphoSilicate Glass (BPSG), Silicon OxyNitride (SiON), or the like. Here, the Silicon Nitride can be formed to a thickness of several hundred A by chemical vapor deposition by reacting SiH2CI2/NH3 at 700 - 900°C for several minutes. The polyimide, SOG, USG, and BPSG can be formed by a coating method.
Owing to the buffer layer 18, the oxidized porous silicon layer 16 has an even surface, thereby enabling stable performance of the subsequent process.
Then, referring to FIG. 7, a passive element 100 is deposited on the buffer layer 18. The passive element 100 may be a resistor, an inductor, or a capacitor, for example. To form the passive element 100 on the buffer layer 18, an electroplating process or deposition process may be used. In general, if the electroplating process is performed such that a seed layer (not shown) for electroplating is thinly formed on the buffer layer 18, then photoresist patterns (not shown) are formed on the seed layer, and as a result, the seed layer is exposed between the photoresist patterns and a metal layer is electroplated on the exposed seed layer. Otherwise, the electroplating process can be performed after forming the photoresist patterns on the buffer layer 18, and then forming the seed layer between the photoresist patterns. Further, if the deposition process is selected, a desired passive element can be formed by depositing a metal layer on the buffer layer 18, depositing the photoresist patterns thereon, and then, etching the metal layer that is exposed between the photoresist patterns. <Second Embodiment
FIGS. 8 through 12A are cross-sectional views for explaining a second embodiment of a method of manufacturing a high-frequency device using an oxidized silicon layer. The second embodiment is differentiated from the first embodiment in that an oxidized porous silicon layer is selectively formed on the silicon substrate. Elements in the second embodiment that are the same as in the first embodiment will be denoted by the same reference numerals.
Referring to FIG. 8, an aluminum electrode 14 and a mask layer 20 are formed at the bottom and top of a silicon substrate 10, respectively. The mask layer 20 will prevent anodizing of the silicon substrate 10 below the mask layer 20 during the subsequent anodizing. Also, the mask layer 20 may be formed of a photoresist material or a silicon nitride. The patterning of the mask layer 20 is performed with • a general photolithography process commonly used in manufacturing a semiconductor device. Referring to FIG. 9, the substrate 10 having the mask layer 20 is placed in the aforementioned anodizing reactor and then anodizing is performed thereon so as to form a porous silicon layer 12 only on a portion of the silicon substrate that is not coated with the mask layer 20. Next, referring to FIG. 10, the silicon substrate 10 is taken away from the anodizing reactor, and then the mask layer 20 and the aluminum electrode 14 are removed.
Then, referring to FIG. 11 , the porous silicon layer 12 is oxidized as described above to form an oxidized silicon layer 16.
Next, referring to FIG. 12A, a natural oxide layer (not shown) formed on the silicon substrate 10 is removed, and then, an insulating buffer layer 18 is formed over the silicon substrate 10 as described above. Then, a passive element 100 is formed on a portion where the oxidized porous silicon layer 16 is formed and active elements 200, such as a transistor, are integrated on a portion where the oxidized porous silicon layer 16 is not formed. <Third Embodiment
FIG. 12B is a cross-sectional view of a high-frequency device using an oxidized porous silicon layer according to a third embodiment of the present invention. The third embodiment is almost the same as the second embodiment, except that a buffer layer 18 is formed only on an oxidized porous silicon layer 16.
Here, the buffer layer 18 prevents the irregular surface of the oxidized porous silicon layer 16. To form the buffer layer 18 only on the oxidized porous silicon layer 16, a general photolithography process can be used. <Fourth Embodiment
FIGS. 13 through 17A are cross-sectional views for explaining a method of manufacturing a high-frequency device using an oxidized porous silicon layer according to a fourth embodiment of the present invention. The fourth embodiment is variation of the second embodiment of selectively forming an oxidized porous silicon layer on a silicon substrate. Here, elements that are the same as in the first and second embodiments will be denoted by the same reference numerals.
Referring to FIG. 13, a mask layer 20 is formed over a silicon substrate 10.
This mask layer 20 prevents anodizing of the silicon substrate 10 below the mask layer 20 during the subsequent anodizing process, and may be formed of a photoresist material or silicon nitride. Patterning of the mask layer 20 is performed by a general photolithography process common in manufacturing semiconductor devices. Next, referring to FIG. 14, impurity ions, such as phosphorous, boron or acenium, are implanted into an exposed portion of the silicon substrate 10 on which the mask layer 20 is formed, thereby forming an impurity-ion implantation region 22. Alternatively, impurity ions may be diffused into the silicon substrate 10 to form an impurity-ion diffusion region.
Then, referring to FIG. 15, the mask layer 20 is removed and then an aluminum electrode 14 is deposited at the bottom of the silicon substrate 10.
Thereafter, referring to FIG. 16, the silicon substrate 10 having the aluminum electrode 14 at its bottom is placed in the aforementioned anodizing reactor and anodizing is performed thereon. At this time, a porous silicon layer
22 is formed over the silicon substrate 10, except for the impurity-ion implantation region 22. Once the anodizing is completed, the silicon substrate 10 is taken away from the anodizing reactor and then the aluminum electrode 14 is removed.
Next, referring to FIG. 17A, the porous silicon layer 12 is oxidized to form an oxidized porous silicon layer 16 as described above. Then, a natural oxide layer (not shown) is removed from the silicon substrate 10, and then, an insulating buffer layer 18 is formed over the silicon substrate 18 as described above. Next, passive elements 100 are formed on the oxidized porous silicon layer 16 and an active element 200 such as a transistor is integrated on the impurity-ion implantation region 22 on which the oxidized porous silicon layer 16 is not formed.
<Fifth Element>
FIG. 17B is a cross-sectional view of a high-frequency device using an oxidized porous silicon layer according to a fifth embodiment of the present invention. The fifth embodiment is almost the same as the fourth embodiment, except that buffer layers 18 are formed only on an oxidized porous silicon layer
16 that is selectively formed.
Industrial Applicability
While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. For instance, these embodiments of the present invention use anodizing to form an oxidized porous silicon layer, but other methods can be adopted to form a thick insulating layer below a passive element 100.
As described above, according to the present invention, a buffer layer is adopted to prevent the surface of an oxidized porous silicon layer from being formed unevenly, thereby stably and easily forming a passive element during the subsequent process.
Also, according to the present invention, even if an oxidized porous silicon layer has an uneven surface, it is possible to stably form a passive element due to a buffer layer made during the subsequent process. Accordingly, an oxidized porous silicon layer can be thickly formed and thus it is possible to suppress deterioration in the performance of a semiconductor device due to semi-conducting characteristics of silicon.

Claims

What is claimed is:
1. A high-frequency device using an oxidized porous silicon layer, the high-frequency device comprising: a silicon substrate; an oxidized porous silicon substrate formed on the silicon substrate; an insulating buffer layer formed on the oxidized porous silicon layer; and a passive element formed on the buffer layer.
2. The high-frequency device of claim 1 , wherein the buffer layer is formed of one selected from the group consisting of Silicon Nitride,
BenzoCycloButene (BCB), polyimide, Tetraethyl OrthoSilicate (TEOS)-silicon oxide, Spin-On-Glass (SOG), Undoped CVD SiO2 (USG), BoroSilicate Glass (BSG), BoroPhosphoSilicate Glass (BPSG), and Silicon OxyNitride (SiON).
3. The high-frequency device of claim 1 , wherein the passive element is one of a resistor, an inductor, and a capacitor.
4. The high-frequency device of claim 1 , wherein the oxidized porous silicon layer is formed on the overall surface of the silicon substrate.
5. The high-frequency device of claim 1 , wherein the oxidized porous silicon layer is selectively formed on a portion of the surface of the silicon substrate.
6. The high-frequency device of claim 5, wherein the buffer layer is formed both on the oxidized porous silicon layer and on portions of the substrate on which the oxidized porous silicon layer is not formed.
7. The high-frequency device of claim 6 further comprising an active element on the buffer layer formed on portions of the silicon substrate on which the oxidized silicon layer is not formed.
8. The high-frequency device of claim 5, wherein the buffer layer is formed only on the oxidized porous silicon layer that is selectively formed.
9. The high-frequency device of claim 8 further comprising an active element on portions of the silicon substrate on which the oxidized porous silicon layer and the buffer layer are not formed.
10. The high-frequency device of claim 7 or 9, wherein the active element comprises at least one transistor.
11. The high-frequency device of claim 5 further comprising an impurity-ion implantation region on the portions of the silicon substrate on which the oxidized porous silicon layer is not formed.
12. The high-frequency device of claim 5 further comprising an impurity-ion diffusion region on the silicon substrate on which the oxidized porous silicon layer is not formed.
13. The high-frequency device of claim 1 , wherein the oxidized porous silicon layer is formed to a thickness of at least 10 μm.
14. A method of manufacturing a high-frequency device using an oxidized porous silicon layer, the method comprising: forming an oxidized porous silicon layer on a silicon substrate; forming an insulating buffer layer on the oxidized porous silicon layer; and forming a passive element on the buffer layer.
15. The method of claim 14, wherein the buffer layer is formed of one selected from the group consisting of Silicon Nitride, BenzoCycloButene (BCB), polyimide, Tetraethyl OrthoSilicate (TEOS)-silicon oxide, Spin-On-Glass (SOG), Undoped CVD SiO2 (USG), BoroSilicate Glass (BSG), BoroPhosphoSilicate Glass (BPSG), and Silicon OxyNitride (SiON).
16. The method of claim 14, wherein the passive element is one of a resistor, an inductor, and a capacitor.
17. The method of claim 14, wherein forming the oxidized porous silicon layer on the silicon substrate comprises: forming an aluminum electrode at the bottom of the silicon substrate; forming porosities on the surface of the silicon substrate by anodizing the silicon substrate; removing the aluminum electrode; and forming an oxidized porous silicon layer by oxidizing the surface of the porous silicon substrate.
18. The method of claim 14, wherein forming the oxidized porous silicon layer on the silicon substrate comprises: forming an aluminum electrode at the bottom of the silicon substrate; selectively forming mask patterns over the silicon substrate for exposing the surface of the silicon substrate; forming porosities on the surface of the silicon substrate having the mask patterns by anodizing the silicon substrate; removing the mask patterns and the aluminum electrode; and forming an oxidized porous silicon layer by oxidizing the surface of the porous silicon substrate.
19. The method of claim 15, wherein the mask patterns are photoresist patterns or silicon nitride patterns.
20. The method of claim 14, wherein forming the oxidized porous silicon layer on the silicon substrate comprises: selectively forming mask patterns on the silicon substrate for exposing the surface of the silicon substrate; inducing impurity ions into the exposed silicon substrate defined by the mask patterns; removing the mask patterns; forming an aluminum electrode at the bottom of the silicon substrate; forming porosities on the surface of the silicon substrate into which the impurity ions are not induced by anodizing the silicon substrate; removing the aluminum electrode; and forming an oxidized porous silicon layer by oxidizing the surface of the porous silicon substrate.
21. The method of claim 20, wherein implanting the impurity ions is performed by an ion implantation method or an ion diffusion method.
22. The method of claim 18 or 20, wherein the buffer layer is formed on the overall surface of the silicon substrate on which the oxidized porous silicon layer and the oxidized silicon layer are not formed.
23. The method of claim 18 or 20, wherein the buffer layer is formed only on the oxidized porous silicon layer.
24. The method of claim 18 or 20 further comprising an active element on the silicon substrate on which the oxidized porous silicon layer is not formed.
PCT/KR2003/000172 2002-01-28 2003-01-27 High-frequency device using oxidized porous silicon layer WO2003065422A1 (en)

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