This invention relates generally to semiconductor structures and devices and to a method for their fabrication, and more specifically to compound semiconductor structures and devices and to the fabrication and use of semiconductor structures, devices, and integrated circuits that include a monocrystalline compound semiconductor material.
The vast majority of semiconductor discrete devices and integrated circuits are fabricated from silicon, at least in part because of the availability of inexpensive, high quality monocrystalline silicon substrates. Other semiconductor materials, such as the so called compound semiconductor materials, have physical attributes, including wider bandgap and/or higher mobility than silicon, or direct bandgaps that makes these materials advantageous for certain types of semiconductor devices. Unfortunately, compound semiconductor materials are generally much more expensive than silicon and are not available in large wafers as is silicon. Gallium arsenide (GaAs), the most readily available compound semiconductor material, is available in wafers only up to about 150 millimeters (mm) in diameter. In contrast, silicon wafers are available up to about 300 mm and are widely available at 200 mm. The 150 mm GaAs wafers are many times more expensive than are their silicon counterparts. Wafers of other compound semiconductor materials are even less available and are more expensive than GaAs.
Because of the desirable characteristics of compound semiconductor materials, and because of their present generally high cost and low availability in bulk form, for many years attempts have been made to grow thin films of the compound semiconductor materials on a foreign substrate. To achieve optimal characteristics of the compound semiconductor material, however, a monocrystalline film of high crystalline quality is desired. Attempts have been made, for example, to grow layers of a monocrystalline compound semiconductor material on germanium, silicon, and various insulators. These attempts have generally been unsuccessful because lattice mismatches between the host crystal and the grown crystal have caused the resulting thin film of compound semiconductor material to be of low crystalline quality.
If a large area thin film of high quality monocrystalline compound semiconductor material was available at low cost, a variety of semiconductor devices could advantageously be fabricated in that film at a low cost compared to the cost of fabricating such devices on a bulk wafer of compound semiconductor material or in an epitaxial film of such material on a bulk wafer of compound semiconductor material. In addition, if a thin film of high quality monocrystalline compound semiconductor material could be realized on a bulk wafer such as a silicon wafer, an integrated device structure could be achieved that took advantage of the best properties of both the silicon and the compound semiconductor material.
Accordingly, a need exists for a semiconductor structure that provides a high quality monocrystalline compound semiconductor film over another monocrystalline material and for a process for making such a structure.
The present invention is illustrated by way of example and not limitation in the accompanying figures, in which like references indicate similar elements, and in which:
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
In accordance with one embodiment of the invention, structure 20 also includes an amorphous intermediate layer 28 positioned between substrate 22 and accommodating buffer layer 24. Structure 20 may also include a template layer 30 between the accommodating buffer layer and compound semiconductor layer 26. As will be explained more fully below, the template layer helps to initiate the growth of the compound semiconductor layer on the accommodating buffer layer. The amorphous intermediate layer helps to relieve the strain in the accommodating buffer layer and by doing so, aids in the growth of a high crystalline quality accommodating buffer layer.
Substrate 22, in accordance with an embodiment of the invention, is a monocrystalline semiconductor wafer, preferably of large diameter. The wafer can be of a material from Group IV of the periodic table, and preferably a material from Group IVA. Examples of Group IV semiconductor materials include silicon, germanium, mixed silicon and germanium, mixed silicon and carbon, mixed silicon, germanium and carbon, and the like. Preferably substrate 22 is a wafer containing silicon or germanium, and most preferably is a high quality monocrystalline silicon wafer as used in the semiconductor industry. Accommodating buffer layer 24 is preferably a monocrystalline oxide or nitride material epitaxially grown on the underlying substrate. In accordance with one embodiment of the invention, amorphous intermediate layer 28 is grown on substrate 22 at the interface between substrate 22 and the growing accommodating buffer layer by the oxidation of substrate 22 during the growth of layer 24. The amorphous intermediate layer serves to relieve strain that might otherwise occur in the monocrystalline accommodating buffer layer as a result of differences in the lattice constants of the substrate and the buffer layer. As used herein, lattice constants refers to the distance between atoms of a cell measured in the plane of the surface. If such strain is not relieved by the amorphous intermediate layer, the strain may cause defects in the crystalline structure of the accommodating buffer layer. Defects in the crystalline structure of the accommodating buffer layer, in turn, would make it difficult to achieve a high quality crystalline structure in monocrystalline compound semiconductor layer 26.
Accommodating buffer layer 24 is preferably a monocrystalline oxide or nitride material selected for its crystalline compatibility with the underlying substrate and with the overlying compound semiconductor material. For example, the material could be an oxide or nitride having a lattice structure matched to the substrate and to the subsequently applied semiconductor material. Materials that are suitable for the accommodating buffer layer include metal oxides such as the alkaline earth metal titanates, alkaline earth metal zirconates, alkaline earth metal hafnates, alkaline earth metal tantalates, alkaline earth metal ruthenates, alkaline earth metal niobates, alkaline earth metal vanadates, alkaline earth metal tin-based perovskites, lanthanum aluminate, lanthanum scandium oxide, and gadolinium oxide. Additionally, various nitrides such as gallium nitride, aluminum nitride, and boron nitride may also be used for the accommodating buffer layer. Most of these materials are insulators, although strontium ruthenate, for example, is a conductor. Generally, these materials are metal oxides or metal nitrides, and more particularly, these metal oxide or nitrides typically include at least two different metallic elements. In some specific applications, the metal oxides or nitride may include three or more different metallic elements.
Amorphous interface layer 28 is preferably an oxide formed by the oxidation of the surface of substrate 22, and more preferably is composed of a silicon oxide. The thickness of layer 28 is sufficient to relieve strain attributed to mismatches between the lattice constants of substrate 22 and accommodating buffer layer 24. Typically, layer 28 has a thickness in the range of approximately 0.5–5 nm.
The compound semiconductor material of layer 26 can be selected, as needed for a particular semiconductor structure, from any of the Group IIIA and VA elements (III–V semiconductor compounds), mixed III–V compounds, Group II(A or B) and VIA elements (II–VI semiconductor compounds), and mixed II–VI compounds. Examples include gallium arsenide (GaAs), gallium indium arsenide (GaInAs), gallium aluminum arsenide (GaAlAs), indium phosphide (InP), cadmium sulfide (CdS), cadmium mercury telluride (CdHgTe), zinc selenide (ZnSe), zinc sulfur selenide (ZnSSe), and the like. Suitable template materials chemically bond to the surface of the accommodating buffer layer 24 at selected sites and provide sites for the nucleation of the epitaxial growth of the subsequent compound semiconductor layer 26. Appropriate materials for template 30 are discussed below.
The following non-limiting, illustrative examples illustrate various combinations of materials useful in structure 20 and structure 40 in accordance with various alternative embodiments of the invention. These examples are merely illustrative, and it is not intended that the invention be limited to these illustrative examples.
In accordance with one embodiment of the invention, monocrystalline substrate 22 is a silicon substrate oriented in the (100) direction. The silicon substrate can be, for example, a silicon substrate as is commonly used in making complementary metal oxide semiconductor (CMOS) integrated circuits having a diameter of about 200–300 mm. In accordance with this embodiment of the invention, accommodating buffer layer 24 is a monocrystalline layer of SrzBa1−zTiO3 where z ranges from 0 to 1 and the amorphous intermediate layer is a layer of silicon oxide (SiOx) formed at the interface between the silicon substrate and the accommodating buffer layer. The value of z is selected to obtain one or more lattice constants closely matched to corresponding lattice constants of the subsequently formed layer 26. The accommodating buffer layer can have a thickness of about 2 to about 100 nanometers (nm) and preferably has a thickness of about 10 nm. In general, it is desired to have an accommodating buffer layer thick enough to isolate the compound semiconductor layer from the substrate to obtain the desired electrical and optical properties. Layers thicker than 100 nm usually provide little additional benefit while increasing cost unnecessarily; however, thicker layers may be fabricated if needed. The amorphous intermediate layer of silicon oxide can have a thickness of about 0.5–5 nm, and preferably a thickness of about 1.5–2.5 nm.
In accordance with this embodiment of the invention, compound semiconductor material layer 26 is a layer of gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs) having a thickness of about 1 nm to about 100 micrometers (μm) and preferably a thickness of about 0.5 μm to 10 μm. The thickness generally depends on the application for which the layer is being prepared. To facilitate the epitaxial growth of the gallium arsenide or aluminum gallium arsenide on the monocrystalline oxide, a template layer is formed by capping the oxide layer. The template layer is preferably 1–10 monolayers of Ti—As, Sr—O—As, Sr—Ga—O, or Sr—Al—O. By way of a preferred example, 1–2 monolayers of Ti—As or Sr—Ga—O have been shown to successfully grow GaAs layers.
In accordance with a further embodiment of the invention, monocrystalline substrate 22 is a silicon substrate as described above. The accommodating buffer layer is a monocrystalline oxide of strontium or barium zirconate or hafnate in a cubic or orthorhombic phase with an amorphous intermediate layer of silicon oxide formed at the interface between the silicon substrate and the accommodating buffer layer. The accommodating buffer layer can have a thickness of about 2–100 nm and preferably has a thickness of at least 5 nm to ensure adequate crystalline and surface quality and is formed of a monocrystalline SrZrO3, BaZrO3, SrHfO3, BaSnO3 or BaHfO3. For example, a monocrystalline oxide layer of BaZrO3 can grow at a temperature of about 700 degrees C. The lattice structure of the resulting crystalline oxide exhibits a 45 degree rotation with respect to the substrate silicon lattice structure.
An accommodating buffer layer formed of these zirconate or hafnate materials is suitable for the growth of compound semiconductor materials in the indium phosphide (InP) system. The compound semiconductor material can be, for example, indium phosphide (InP) or indium gallium arsenide (InGaAs) having a thickness of about 1.0 nm to 10 μm. A suitable template for this structure is 1–10 monolayers of zirconium-arsenic (Zr—As), zirconium-phosphorus (Zr—P), hafnium-arsenic (Hf—As), hafnium-phosphorus (Hf—P), strontium-oxygen-arsenic (Sr—O—As), strontium-oxygen-phosphorus (Sr—O—P), barium-oxygen-arsenic (Ba—O—As), indium-strontium-oxygen (In—Sr—O), or barium-oxygen-phosphorus (Ba—O—P), and preferably 1–2 monolayers of one of these materials. By way of an example, for a barium zirconate accommodating buffer layer, the surface is terminated with 1–2 monolayers of zirconium followed by deposition of 1–2 monolayers of arsenic to form a Zr—As template. A monocrystalline layer of the compound semiconductor material from the indium phosphide system is then grown on the template layer. The resulting lattice structure of the compound semiconductor material exhibits a 45 degree rotation with respect to the accommodating buffer layer lattice structure and a lattice mismatch to (100) InP of less than 2.5%, and preferably less than about 1.0%.
In accordance with a further embodiment of the invention, a structure is provided that is suitable for the growth of an epitaxial film of a II–VI material overlying a silicon substrate. The substrate is preferably a silicon wafer as described above. A suitable accommodating buffer layer material is SrxBa1−xTiO3, where x ranges from 0 to 1, having a thickness of about 2–100 nm and preferably a thickness of about 5–15 nm. The II-VI compound semiconductor material can be, for example, zinc selenide (ZnSe) or zinc sulfur selenide (ZnSSe). A suitable template for this material system includes 1–10 monolayers of zinc-oxygen (Zn—O) followed by 1–2 monolayers of an excess of zinc followed by the selenidation of zinc on the surface. Alternatively, a template can be, for example, strontium-sulfur (Sr—S) followed by the ZnSeS.
This embodiment of the invention is an example of structure 40 illustrated in
This example also illustrates materials useful in a structure 40 as illustrated in
Referring again to
In accordance with one embodiment of the invention, substrate 22 is a (100) or (111) oriented monocrystalline silicon wafer and accommodating buffer layer 24 is a layer of strontium barium titanate. Substantial matching of lattice constants between these two materials is achieved by rotating the crystal orientation of the titanate material by 45° with respect to the crystal orientation of the silicon substrate wafer. The inclusion in the structure of amorphous interface layer 24, a silicon oxide layer in this example, serves to reduce strain in the titanate monocrystalline layer that might result from any mismatch in the lattice constants of the host silicon wafer and the grown titanate layer. As a result, in accordance with an embodiment of the invention, a high quality, thick monocrystalline titanate layer is achievable.
Still referring to
The following example illustrates a process, in accordance with one embodiment of the invention, for fabricating a semiconductor structure such as the structures depicted in
In accordance with an alternate embodiment of the invention, the native silicon oxide can be converted and the substrate surface can be prepared for the growth of a monocrystalline oxide layer by depositing strontium oxide onto the substrate surface by MBE at a low temperature and by subsequently heating the structure to a temperature of about 750° C. At this temperature a solid state reaction takes place between the strontium oxide and the native silicon oxide causing the reduction of the native silicon oxide and leaving an ordered 2×1 structure with strontium, oxygen, and silicon remaining on the substrate surface. Again, this forms a template for the subsequent growth of an ordered monocrystalline oxide layer.
Following the removal of the silicon oxide from the surface of the substrate, in accordance with one embodiment of the invention, the substrate is cooled to a temperature in the range of about 400–600° C. and a layer of strontium titanate is grown on the template layer by molecular beam epitaxy. The MBE process is initiated by opening shutters in the MBE apparatus to expose strontium, titanium and oxygen sources. The ratio of strontium and titanium is approximately 1:1. The partial pressure of oxygen is initially set at a minimum value to grow stochiometric strontium titanate at a growth rate of about 0.3–0.5 nm per minute. After initiating growth of the strontium titanate, the partial pressure of oxygen is increased above the initial minimum value. The overpressure of oxygen causes the growth of an amorphous silicon oxide layer at the interface between the underlying substrate and the growing strontium titanate layer. The growth of the silicon oxide layer results from the diffusion of oxygen through the growing strontium titanate layer to the interface where the oxygen reacts with silicon at the surface of the underlying substrate. The strontium titanate grows as an ordered monocrystal with the crystalline orientation rotated by 45° with respect to the ordered 2×1 crystalline structure of the underlying substrate. Strain that otherwise might exist in the strontium titanate layer because of the small mismatch in lattice constant between the silicon substrate and the growing crystal is relieved in the amorphous silicon oxide intermediate layer.
After the strontium titanate layer has been grown to the desired thickness, the monocrystalline strontium titanate is capped by a template layer that is conducive to the subsequent growth of an epitaxial layer of a desired compound semiconductor material. For the subsequent growth of a layer of gallium arsenide, the MBE growth of the strontium titanate monocrystalline layer can be capped by terminating the growth with 1–2 monolayers of titanium, 1–2 monolayers of titanium-oxygen or with 1–2 monolayers of strontium-oxygen. Following the formation of this capping layer, arsenic is deposited to form a Ti—As bond, a Ti—O—As bond or a Sr—O—As. Any of these form an appropriate template for deposition and formation of a gallium arsenide monocrystalline layer. Following the formation of the template, gallium is introduced to the reaction with the arsenic and gallium arsenide forms. Alternatively, gallium can be deposited on the capping layer to form a Sr—O—Ga bond, and arsenic is introduced with the gallium to form the GaAs.
The structure illustrated in
The process described above illustrates a process for forming a semiconductor structure including a silicon substrate, a monocrystalline strontium titanate accommodating buffer layer, and a monocrystalline gallium arsenide compound semiconductor layer by the process of molecular beam epitaxy. The process can also be carried out by the process of chemical vapor deposition (CVD), metal organic chemical vapor deposition (MOCVD), migration enhanced epitaxy (MEE), atomic layer epitaxy (ALE), or the like. Further, by a similar process, other monocrystalline accommodating buffer layers such as alkaline earth metal titanates, zirconates, hafnates, tantalates, vanadates, ruthenates, and niobates, alkaline earth metal tin-based perovskites, lanthanum aluminate, lanthanum scandium oxide, and gadolinium oxide can also be grown. Further, by a similar process such as MBE, other III-V and II-VI monocrystalline compound semiconductor layers can be deposited overlying the monocrystalline oxide accommodating buffer layer.
Each of the variations of compound semiconductor materials and monocrystalline oxide accommodating buffer layer uses an appropriate template for initiating the grown of the compound semiconductor layer. For example, if the accommodating buffer layer is alkaline earth metal zirconate, the oxide can be capped by a thin layer of zirconium. The deposition of zirconium can be followed by the deposition of arsenic or phosphorus to react with the zirconium as a precursor to depositing indium gallium arsenide, indium aluminum arsenide, or indium phosphide respectively. Similarly, if the monocrystalline oxide accommodating buffer layer is an alkaline earth metal hafnate, the oxide layer can be capped by a thin layer of hafnium. The deposition of hafnium is followed by the deposition of arsenic or phosphorous to react with the hafnium as a precursor to the growth of an indium gallium arsenide, indium aluminum arsenide, or indium phosphide layer, respectively. In a similar manner, strontium titanate can be capped with a layer of strontium or strontium and oxygen and barium titanate can be capped with a layer of barium or barium and oxygen. Each of these depositions can be followed by the deposition of arsenic or phosphorus to react with the capping material to form a template for the deposition of a compound semiconductor material layer comprising indium gallium arsenide, indium aluminum arsenide, or indium phosphide.
Insulating material 58 and any other layers that may have been formed or deposited during the processing of semiconductor component 56 in region 53 are removed from the surface of region 54 to provide a bare silicon surface in that region. As is well known, bare silicon surfaces are highly reactive and a native silicon oxide layer can quickly form on the bare surface. A layer of barium or barium and oxygen is deposited onto the native oxide layer on the surface of region 54 and is reacted with the oxidized surface to form a first template layer (not shown). In accordance with one embodiment of the invention a monocrystalline oxide layer 60 is formed overlying the template layer by a process of molecular beam epitaxy. Reactants including barium, titanium and oxygen are deposited onto the template layer to form the monocrystalline oxide layer. Initially during the deposition the partial pressure of oxygen is kept near the minimum necessary to fully react with the barium and titanium to form monocrystalline barium titanate layer 60. The partial pressure of oxygen is then increased to provide an overpressure of oxygen and to allow oxygen to diffuse through the growing monocrystalline oxide layer. The oxygen diffusing through the barium titanate reacts with silicon at the surface of region 54 to form an amorphous layer 62 of silicon oxide on the second region and at the interface between the silicon substrate and the monocrystalline oxide.
In accordance with an embodiment of the invention, the step of depositing monocrystalline oxide layer 60 is terminated by depositing a second template layer 64, which can be 1–10 monolayers of titanium., barium, barium and oxygen, or titanium and oxygen. A layer 66 of a monocrystalline compound semiconductor material is then deposited overlying the second template layer by a process of molecular beam epitaxy. The deposition of layer 66 is initiated by depositing a layer of arsenic onto the template. This initial step is followed by depositing gallium and arsenic to form monocrystalline gallium arsenide. Alternatively, strontium can be substituted for barium in the above example.
In accordance with a further embodiment of the invention, a semiconductor component, generally indicated by a dashed line 68 is formed in compound semiconductor layer 66. Semiconductor component 68 can be formed by processing steps conventionally used in the fabrication of gallium arsenide or other III–V compound semiconductor material devices. Semiconductor component 68 can be any active or passive component, and preferably is a semiconductor laser, light emitting diode, photodetector, heterojunction bipolar transistor (HBT), high frequency MESFET, or other component that utilizes and takes advantage of the physical properties of compound semiconductor materials. A metallic conductor schematically indicated by the line 70 can be formed to electrically couple device 68 and device 56, thus implementing an integrated device that includes at least one component formed in the silicon substrate and one device formed in the monocrystalline compound semiconductor material layer. Although illustrative structure 50 has been described as a structure formed on a silicon substrate 52 and having a barium (or strontium) titanate layer 60 and a gallium arsenide layer 66, similar devices can be fabricated using other substrates, monocrystalline oxide layers and other compound semiconductor layers as described elsewhere in this disclosure.
A semiconductor component generally indicated by a dashed line 92 is formed at least partially in monocrystalline semiconductor layer 86. In accordance with one embodiment of the invention, semiconductor component 92 may include a field effect transistor having a gate dielectric formed, in part, by monocrystalline oxide layer 88. In addition, monocrystalline semiconductor layer 92 can be used to implement the gate electrode of that field effect transistor. In accordance with one embodiment of the invention, monocrystalline semiconductor layer 86 is formed from a group III-V compound and semiconductor component 92 is a radio frequency amplifier that takes advantage of the high mobility characteristic of group III–V component materials. In accordance with yet a further embodiment of the invention, an electrical interconnection schematically illustrated by the line 94 electrically interconnects component 78 and component 92. Structure 72 thus integrates components that take advantage of the unique properties of the two monocrystalline semiconductor materials.
By way of more specific examples, other integrated circuits and systems are illustrated in
An integrated circuit is generally a combination of at least two circuit elements (e.g., transistors, diodes, resistors, capacitors, and the like) inseparably associated on or within a continuous substrate. The integrated circuit 102 includes a compound semiconductor portion 1022, a bipolar portion 1024, and an MOS portion 1026. The compound semiconductor portion 1022 includes electrical components that are formed at least partially within a compound semiconductor material. Transistors and other electrical components within the compound semiconductor portion 1022 are capable of processing signals at radio frequencies of at least approximately 0.8 GHz. In other embodiments, the signals could be at lower or higher frequencies. For example, some materials, such as indium gallium arsenide, are capable of processing signals at radio frequency signals at approximately 27 GHz.
The compound semiconductor portion 1022 further includes a duplexer 10222, a radio frequency-to-baseband converter 10224 (demodulating means or demodulating circuit), baseband-to-radio frequency converter 10226 (modulating means or modulating circuit), a power amplifier 10228, and an isolator 10229. The bipolar portion 1024 and the MOS portion 1026 typically are formed in a Group IV semiconductive material. The bipolar portion 1024 includes a receiving amplifier 10242, an analog-to-digital converter 10244, a digital-to-analog converter 10246, and a transmitting amplifier 10248. The MOS portion 1026 includes a digital signal processing means 10262. An example of such means includes any one of the commonly available DSP cores available in the market, such as the Motorola DSP 566xx (from Motorola, Incorporated of Schaumburg, Ill.) and Texas Instruments TMS 320C54x (from Texas Instruments of Dallas, Tex.) families of digital signal processors. This digital signal processing means 10262 typically includes complementary MOS (CMOS) transistors and analog-to-digital and digital-to-analog converters. Clearly, other electrical components are present in the integrated circuit 102.
In one mode of operation, the communicating device 100 receives a signal from an antenna, which is part of the signal transceiving means 101. The signal passes through the duplexer 10227 to the radio frequency-to-baseband converter 10224. The analog data or other information is amplified by receiving amplifier 10224 and transmitted to the digital signal processing means 10262. After the digital signal processing means 10262 has processed the information or other data, the processed information or other data is transmitted to the output unit 103. If the communicating device is a pager, the output unit can be a display. If the communicating device is a cellular telephone, the output unit 103 can include a speaker, a display, or both.
Data or other information can be sent through the communicating device 100 in the opposite direction. The data or other information will come in through the input unit 104. In a cellular telephone, this could include a microphone or a keypad. The information or other data is then processed using the digital signal processing means 10262. After processing, the signal is then converted using the digital-to-analog converter 10246. The converted signal is amplified by the transmitting amplifier 10248. The amplified signal is modulated by the baseband-to-radio frequency converter 10226 and further amplified by power amplifier 10228. The amplified RF signal passes through the isolator 10229 and duplexer 10222 to the antenna.
Prior art embodiments of the communicating device 100 would have at least two separate integrated circuits: one for the compound semiconductor portion 1022 and one for the MOS portion 1026. The bipolar portion 1024 may be on the same integrated circuit as the MOS portion 1026 or could be on still another integrated circuit. With an embodiment of the present invention, all three portions can now be formed within a single integrated circuit. Because all of the transistors can reside on a single integrated circuit, the communicating device can be greatly miniaturized and allow for greater portability of a communicating device.
Attention is now directed to a method for forming exemplary portions of the integrated circuit 102 as illustrated in
A p-type dopant is introduced into the drift region 1117 to form an active or intrinsic base region 1114. An n-type, deep collector region 1108 is then formed within the bipolar portion 1024 to allow electrical connection to the buried region 1102. Selective n-type doping is performed to form N+ doped regions 1116 and the emitter region 1120. N+ doped regions 1116 are formed within layer 1104 along adjacent sides of the gate electrode 1112 and are source, drain, or source/drain regions for the MOS transistor. The N+ doped regions 1116 and emitter region 1120 have a doping concentration of at least 1E19 atoms per cubic centimeter to allow ohmic contacts to be formed. A p-type doped region is formed to create the inactive or extrinsic base region 1118 which is a P+ doped region (doping concentration of at least 1E19 atoms per cubic centimeter).
In the embodiment described, several processing steps have been performed but are not illustrated or further described, such as the formation of well regions, threshold adjusting implants, channel punchthrough prevention implants, field punchthrough prevention implants, as well as a variety of masking layers. The formation of the device up to this point in the process is performed using conventional steps. As illustrated, a standard N-channel MOS transistor has been formed within the MOS region 1026, and a vertical NPN bipolar transistor has been formed within the bipolar portion 1024. As of this point, no circuitry has been formed within the compound semiconductor portion 1022.
All of the layers that have been formed during the processing of the bipolar and MOS portions of the integrated circuit are now removed from the surface of compound semiconductor portion 1022. A bare silicon surface is thus provided for the subsequent processing of this portion, for example in the manner set forth above.
An accommodating buffer layer 124 is then formed over the substrate 110 as illustrated in
A monocrystalline compound semiconductor layer 132 is then epitaxially grown overlying the monocrystalline portion of accommodating buffer layer 124 as shown in
At this point in time, sections of the compound semiconductor layer 132 and the accommodating buffer layer 124 are removed from portions overlying the bipolar portion 1024 and the MOS portion 1026 as shown in
A transistor 144 is then formed within the monocrystalline compound semiconductor portion 1022. A gate electrode 148 is then formed on the monocrystalline compound semiconductor layer 132. Doped regions 146 are then formed within the monocrystalline compound semiconductor layer 132. In this embodiment, the transistor 144 is a metal-semiconductor field-effect transistor (MESFET). If the MESFET is an n-type MESFET, the doped regions 146 and monocrystalline compound semiconductor layer 132 are also n-type doped. If a p-type MESFET were to be formed, then the doped regions 146 and monocrystalline compound semiconductor layer 132 would have just the opposite doping type. The heavier doped (N) regions 146 allow ohmic contacts to be made to the monocrystalline compound semiconductor layer 132. At this point in time, the active devices within the integrated circuit have been formed. This particular embodiment includes an n-type MESFET, a vertical NPN bipolar transistor, and a planar n-channel MOS transistor. Many other types of transistors, including P-channel MOS transistors, p-type vertical bipolar transistors, p-type MESFETs, and combinations of vertical and planar transistors, can be used. Also, other electrical components, such as resistors, capacitors, diodes, and the like, may be formed in one or more of the portions 1022, 1024, and 1026.
Processing continues to form a substantially completed integrated circuit 102 as illustrated in
A passivation layer 156 is formed over the interconnects 1562, 1564, and 1566 and insulating layer 154. Other electrical connections are made to the transistors as illustrated as well as to other electrical or electronic components within the integrated circuit 102 but are not illustrated in the figures. Further, additional insulating layers and interconnects may be formed as necessary to form the proper interconnections between the various components within the integrated circuit 102.
As can be seen from the previous embodiment, active devices for both compound semiconductor and Group IV semiconductor materials can be integrated into a single integrated circuit. Because there is some difficulty in incorporating both bipolar transistors and MOS transistors within a same integrated circuit, it may be possible to move some of the components within bipolar portion into the compound semiconductor portion 1022 or the MOS portion 1024. More specifically, turning to the embodiment as described with respect to
In still another embodiment, an integrated circuit can be formed such that it includes an optical laser in a compound semiconductor portion and an optical interconnect (waveguide) to an MOS transistor within a Group IV semiconductor region of the same integrated circuit.
Another accommodating buffer layer 172, similar to the accommodating buffer layer 164, is formed over the upper mirror layer 170. In an alternative embodiment, the accommodating buffer layers 164 and 172 may include different materials. However, their function is essentially the same in that each is used for making a transition between a compound semiconductor layer and a monocrystalline Group IV semiconductor layer. A monocrystalline Group IV semiconductor layer 174 is formed over the accommodating buffer layer 172. In one particular embodiment, the monocrystalline Grout IV semiconductor layer 174 includes germanium, silicon germanium, silicon germanium carbide, or the like.
In
A monocrystalline Group IV semiconductor layer is epitaxially grown over one of the doped regions 177. An upper portion 184 is P+ doped, and a lower portion 182 remains substantially intrinsic (undoped) as illustrated in
The next set of steps is performed to define the optical laser 180 as illustrated in
Contacts 186 and 188 are formed for making electrical contact to the upper mirror layer 170 and the lower mirror layer 166, respectively, as shown in
An insulating layer 190 is then formed and patterned to define optical openings extending to the contact layer 186 and one of the doped regions 177 as shown in
The balance of the formation of the optical waveguide, which is an optical interconnect, is completed as illustrated in
Processing is continued to form a substantially completed integrated circuit as illustrated in
In other embodiments, other types of lasers can be formed. For example, another type of laser can emit light (photons) horizontally instead of vertically. If light is emitted horizontally, the MOSFET transistor could be formed within the substrate 161, and the optical waveguide would be reconfigured, so that the laser is properly coupled (optically connected) to the transistor. In one specific embodiment, the optical waveguide can include at least a portion of the accommodating buffer layer. Other configurations are possible.
Clearly, these embodiments of integrated circuits having compound semiconductor portions and Group IV semiconductor portions, are meant to illustrate embodiments of the present invention and not limit the present invention. There are multiplicity of other combinations and other embodiments of the present invention. For example, the compound semiconductor portion may include light emitting diodes, photodetectors, diodes, or the like, and the Group IV semiconductor can include digital logic, memory arrays, and most structures that can be formed in conventional MOS integrated circuits. By using embodiments of the present invention, it is now simpler to integrate devices that work better in compound semiconductor materials with other components that work better in Group IV semiconductor materials. This allows a device to be shrunk, the manufacturing costs to decrease, and yield and reliability to increase.
Although not illustrated, a monocrystalline Group IV wafer can be used in forming only compound semiconductor electrical components over the wafer. In this manner, the wafer is essentially a “handle” wafer used during the fabrication of the compound semiconductor electrical components within a monocrystalline compound semiconductor layer overlying the wafer. Therefore, electrical components can be formed within III–V or II–VI semiconductor materials over a wafer of at least approximately 200 millimeters in diameter and possibly at least approximately 300 millimeters.
By the use of this type of substrate, a relatively inexpensive “handle” wafer overcomes the fragile nature of the compound semiconductor wafers by placing them over a relatively more durable and easy to fabricate base material. Therefore, an integrated circuit can be formed such that all electrical components, and particularly all active electronic devices, can be formed within the compound semiconductor material even though the substrate itself may include a Group IV semiconductor material. Fabrication costs for compound semiconductor device should decrease because larger substrates can be processed more economically and more readily compared to the relatively smaller and more fragile, conventional compound semiconductor wafers.
In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
This application is a Divisional of application Ser. No. 10/076,450, filed Feb. 19, 2002 now abandoned, which is a Divisional of application Ser. No. 09/502,023, filed Feb. 10, 2000 now U.S. Pat. No. 6,392,257.
Number | Name | Date | Kind |
---|---|---|---|
3617951 | Anderson | Nov 1971 | A |
3670213 | Nakagawa et al. | Jun 1972 | A |
3758199 | Thaxter | Sep 1973 | A |
3766370 | Walther | Oct 1973 | A |
3802967 | Ladany et al. | Apr 1974 | A |
3818451 | Coleman | Jun 1974 | A |
3914137 | Huffman et al. | Oct 1975 | A |
3935031 | Adler | Jan 1976 | A |
4006989 | Andringa | Feb 1977 | A |
4084130 | Holton | Apr 1978 | A |
4120588 | Chaum | Oct 1978 | A |
4146297 | Alferness et al. | Mar 1979 | A |
4174422 | Matthews et al. | Nov 1979 | A |
4174504 | Chenausky et al. | Nov 1979 | A |
4177094 | Kroon | Dec 1979 | A |
4242595 | Lehovec | Dec 1980 | A |
4284329 | Smith et al. | Aug 1981 | A |
4289920 | Hovel | Sep 1981 | A |
4297656 | Pan | Oct 1981 | A |
4298247 | Michelet et al. | Nov 1981 | A |
4378259 | Hasegawa et al. | Mar 1983 | A |
4392297 | Little | Jul 1983 | A |
4398342 | Pitt et al. | Aug 1983 | A |
4404265 | Manasevit | Sep 1983 | A |
4424589 | Thomas et al. | Jan 1984 | A |
4439014 | Stacy et al. | Mar 1984 | A |
4442590 | Stockton et al. | Apr 1984 | A |
4447116 | King et al. | May 1984 | A |
4452720 | Harada et al. | Jun 1984 | A |
4459325 | Nozawa et al. | Jul 1984 | A |
4482422 | McGinn et al. | Nov 1984 | A |
4482906 | Hovel et al. | Nov 1984 | A |
4484332 | Hawrylo | Nov 1984 | A |
4503540 | Nakashima et al. | Mar 1985 | A |
4523211 | Morimoto et al. | Jun 1985 | A |
4525871 | Foyt et al. | Jun 1985 | A |
4594000 | Falk et al. | Jun 1986 | A |
4626878 | Kuwano et al. | Dec 1986 | A |
4629821 | Bronstein-Bonte et al. | Dec 1986 | A |
4661176 | Manasevit | Apr 1987 | A |
4667088 | Kramer | May 1987 | A |
4667212 | Nakamura | May 1987 | A |
4681982 | Yoshida | Jul 1987 | A |
4695120 | Holder | Sep 1987 | A |
4723321 | Saleh | Feb 1988 | A |
4748485 | Vasudev | May 1988 | A |
4756007 | Qureshi et al. | Jul 1988 | A |
4772929 | Manchester et al. | Sep 1988 | A |
4773063 | Hunsperger et al. | Sep 1988 | A |
4774205 | Choi et al. | Sep 1988 | A |
4777613 | Shahan et al. | Oct 1988 | A |
4793872 | Meunier et al. | Dec 1988 | A |
4801184 | Revelli | Jan 1989 | A |
4802182 | Thornton et al. | Jan 1989 | A |
4804866 | Akiyama | Feb 1989 | A |
4815084 | Scifres et al. | Mar 1989 | A |
4841775 | Ikeda et al. | Jun 1989 | A |
4843609 | Ohya et al. | Jun 1989 | A |
4845044 | Ariyoshi et al. | Jul 1989 | A |
4846926 | Kay et al. | Jul 1989 | A |
4855249 | Akasaki et al. | Aug 1989 | A |
4866489 | Yokogawa et al. | Sep 1989 | A |
4868376 | Lessin et al. | Sep 1989 | A |
4872046 | Morkoc et al. | Oct 1989 | A |
4876208 | Gustafson et al. | Oct 1989 | A |
4876218 | Pessa et al. | Oct 1989 | A |
4876219 | Eshita et al. | Oct 1989 | A |
4882300 | Inoue et al. | Nov 1989 | A |
4885376 | Verkade | Dec 1989 | A |
4888202 | Murakami et al. | Dec 1989 | A |
4889402 | Reinhart | Dec 1989 | A |
4891091 | Shastry | Jan 1990 | A |
4896194 | Suzuki | Jan 1990 | A |
4901133 | Curran et al. | Feb 1990 | A |
4910164 | Shichijo | Mar 1990 | A |
4912087 | Aslam et al. | Mar 1990 | A |
4928154 | Umeno et al. | May 1990 | A |
4934777 | Jou et al. | Jun 1990 | A |
4952420 | Walters | Aug 1990 | A |
4959702 | Moyer et al. | Sep 1990 | A |
4963508 | Umeno et al. | Oct 1990 | A |
4963949 | Wanlass et al. | Oct 1990 | A |
4965649 | Zanio et al. | Oct 1990 | A |
4981714 | Ohno et al. | Jan 1991 | A |
4984043 | Vinal | Jan 1991 | A |
4999842 | Huang et al. | Mar 1991 | A |
5018816 | Murray et al. | May 1991 | A |
5028563 | Feit et al. | Jul 1991 | A |
5028976 | Ozaki et al. | Jul 1991 | A |
5051790 | Hammer | Sep 1991 | A |
5053835 | Horikawa et al. | Oct 1991 | A |
5055445 | Belt et al. | Oct 1991 | A |
5055835 | Sutton | Oct 1991 | A |
5057694 | Idaka et al. | Oct 1991 | A |
5060031 | Abrokwah et al. | Oct 1991 | A |
5063081 | Cozzette et al. | Nov 1991 | A |
5063166 | Mooney et al. | Nov 1991 | A |
5064781 | Cambou et al. | Nov 1991 | A |
5067809 | Tsubota | Nov 1991 | A |
5073981 | Giles et al. | Dec 1991 | A |
5075743 | Behfar-Rad | Dec 1991 | A |
5081062 | Vasudev et al. | Jan 1992 | A |
5081519 | Nishimura | Jan 1992 | A |
5087829 | Ishibashi et al. | Feb 1992 | A |
5103494 | Mozer | Apr 1992 | A |
5116461 | Lebby et al. | May 1992 | A |
5119448 | Schaefer et al. | Jun 1992 | A |
5122679 | Ishii et al. | Jun 1992 | A |
5122852 | Chan et al. | Jun 1992 | A |
5127067 | Delcoco et al. | Jun 1992 | A |
5130762 | Kulick | Jul 1992 | A |
5132648 | Trinh et al. | Jul 1992 | A |
5140387 | Okazaki et al. | Aug 1992 | A |
5140651 | Soref et al. | Aug 1992 | A |
5141894 | Bisaro et al. | Aug 1992 | A |
5143854 | Pirrung et al. | Sep 1992 | A |
5144409 | Ma | Sep 1992 | A |
5148504 | Levi et al. | Sep 1992 | A |
5155658 | Inam et al. | Oct 1992 | A |
5159413 | Calviello et al. | Oct 1992 | A |
5163118 | Lorenzo et al. | Nov 1992 | A |
5166761 | Olson et al. | Nov 1992 | A |
5173474 | Connell et al. | Dec 1992 | A |
5173835 | Cornett et al. | Dec 1992 | A |
5181085 | Moon et al. | Jan 1993 | A |
5185589 | Krishnaswamy et al. | Feb 1993 | A |
5188976 | Kume et al. | Feb 1993 | A |
5191625 | Gustavsson | Mar 1993 | A |
5194397 | Cook et al. | Mar 1993 | A |
5194917 | Regener | Mar 1993 | A |
5198269 | Swartz et al. | Mar 1993 | A |
5208182 | Narayan et al. | May 1993 | A |
5210763 | Lewis et al. | May 1993 | A |
5216359 | Makki et al. | Jun 1993 | A |
5216729 | Berger et al. | Jun 1993 | A |
5221367 | Chisholm et al. | Jun 1993 | A |
5225031 | McKee et al. | Jul 1993 | A |
5227196 | Itoh | Jul 1993 | A |
5238877 | Russell | Aug 1993 | A |
5244818 | Jokers et al. | Sep 1993 | A |
5248564 | Ramesh | Sep 1993 | A |
5260394 | Tazaki et al. | Nov 1993 | A |
5262659 | Grudkowski et al. | Nov 1993 | A |
5266355 | Wernberg et al. | Nov 1993 | A |
5268327 | Vernon | Dec 1993 | A |
5270298 | Ramesh | Dec 1993 | A |
5280013 | Newman et al. | Jan 1994 | A |
5281834 | Cambou et al. | Jan 1994 | A |
5283462 | Stengel | Feb 1994 | A |
5286985 | Taddiken | Feb 1994 | A |
5293050 | Chapple-Sokol et al. | Mar 1994 | A |
5306649 | Hebert | Apr 1994 | A |
5310707 | Oishi et al. | May 1994 | A |
5312765 | Kanber | May 1994 | A |
5313058 | Friederich et al. | May 1994 | A |
5314547 | Heremans et al. | May 1994 | A |
5315128 | Hunt et al. | May 1994 | A |
5323023 | Fork | Jun 1994 | A |
5326721 | Summerfelt | Jul 1994 | A |
5334556 | Guldi | Aug 1994 | A |
5352926 | Andrews | Oct 1994 | A |
5356509 | Terranova et al. | Oct 1994 | A |
5356831 | Calviello et al. | Oct 1994 | A |
5357122 | Okubora et al. | Oct 1994 | A |
5358925 | Neville Connell et al. | Oct 1994 | A |
5362972 | Yazawa et al. | Nov 1994 | A |
5362998 | Iwamura et al. | Nov 1994 | A |
5365477 | Cooper, Jr. et al. | Nov 1994 | A |
5371621 | Stevens | Dec 1994 | A |
5371734 | Fischer | Dec 1994 | A |
5372992 | Itozaki et al. | Dec 1994 | A |
5373166 | Buchan et al. | Dec 1994 | A |
5387811 | Saigoh | Feb 1995 | A |
5391515 | Kao et al. | Feb 1995 | A |
5393352 | Summerfelt | Feb 1995 | A |
5394489 | Koch | Feb 1995 | A |
5395663 | Tabata et al. | Mar 1995 | A |
5397428 | Stoner et al. | Mar 1995 | A |
5399898 | Rostoker | Mar 1995 | A |
5404581 | Honjo | Apr 1995 | A |
5405802 | Yamagata et al. | Apr 1995 | A |
5406202 | Mehrgardt et al. | Apr 1995 | A |
5410622 | Okada et al. | Apr 1995 | A |
5418216 | Fork | May 1995 | A |
5418389 | Watanabe | May 1995 | A |
5420102 | Harshavardhan et al. | May 1995 | A |
5427988 | Sengupta et al. | Jun 1995 | A |
5430397 | Itoh et al. | Jul 1995 | A |
5436759 | Dijaii et al. | Jul 1995 | A |
5438584 | Paoli et al. | Aug 1995 | A |
5441577 | Sasaki et al. | Aug 1995 | A |
5442191 | Ma | Aug 1995 | A |
5442561 | Yoshizawa et al. | Aug 1995 | A |
5444016 | Abrokwah et al. | Aug 1995 | A |
5446719 | Yoshida et al. | Aug 1995 | A |
5450812 | McKee et al. | Sep 1995 | A |
5452118 | Maruska | Sep 1995 | A |
5453727 | Shibasaki et al. | Sep 1995 | A |
5466631 | Ichikawa et al. | Nov 1995 | A |
5473047 | Shi | Dec 1995 | A |
5473171 | Summerfelt | Dec 1995 | A |
5477363 | Matsuda | Dec 1995 | A |
5478653 | Guenzer | Dec 1995 | A |
5479033 | Baca et al. | Dec 1995 | A |
5479317 | Ramesh | Dec 1995 | A |
5480829 | Abrokwah et al. | Jan 1996 | A |
5481102 | Hazelrigg, Jr. | Jan 1996 | A |
5482003 | McKee et al. | Jan 1996 | A |
5484664 | Kitahara et al. | Jan 1996 | A |
5486406 | Shi | Jan 1996 | A |
5491461 | Partin et al. | Feb 1996 | A |
5492859 | Sakaguchi et al. | Feb 1996 | A |
5494711 | Takeda et al. | Feb 1996 | A |
5504035 | Rostoker et al. | Apr 1996 | A |
5504183 | Shi | Apr 1996 | A |
5508554 | Takatani et al. | Apr 1996 | A |
5510665 | Conley | Apr 1996 | A |
5511238 | Bayraktaroglu | Apr 1996 | A |
5512773 | Wolf et al. | Apr 1996 | A |
5514484 | Nashimoto | May 1996 | A |
5514904 | Onga et al. | May 1996 | A |
5515047 | Yamakido et al. | May 1996 | A |
5515810 | Yamashita et al. | May 1996 | A |
5516725 | Chang et al. | May 1996 | A |
5519235 | Ramesh | May 1996 | A |
5523602 | Horiuchi et al. | Jun 1996 | A |
5528057 | Yanagase et al. | Jun 1996 | A |
5528067 | Farb et al. | Jun 1996 | A |
5528209 | Macdonald et al. | Jun 1996 | A |
5528414 | Oakley | Jun 1996 | A |
5530235 | Stefik et al. | Jun 1996 | A |
5538941 | Findikoglu et al. | Jul 1996 | A |
5540785 | Dennard et al. | Jul 1996 | A |
5541422 | Wolf et al. | Jul 1996 | A |
5548141 | Morris et al. | Aug 1996 | A |
5549977 | Jin et al. | Aug 1996 | A |
5551238 | Prueitt | Sep 1996 | A |
5552547 | Shi | Sep 1996 | A |
5553089 | Seki et al. | Sep 1996 | A |
5556463 | Guenzer | Sep 1996 | A |
5559368 | Hu et al. | Sep 1996 | A |
5561305 | Smith | Oct 1996 | A |
5569953 | Kikkawa et al. | Oct 1996 | A |
5570226 | Ota | Oct 1996 | A |
5572052 | Kashihara et al. | Nov 1996 | A |
5574296 | Park et al. | Nov 1996 | A |
5574589 | Feuer et al. | Nov 1996 | A |
5574744 | Gaw et al. | Nov 1996 | A |
5576879 | Nashimoto | Nov 1996 | A |
5578162 | D'Asaro et al. | Nov 1996 | A |
5585167 | Satoh et al. | Dec 1996 | A |
5585288 | Davis et al. | Dec 1996 | A |
5588995 | Sheldon | Dec 1996 | A |
5589284 | Summerfelt et al. | Dec 1996 | A |
5596205 | Reedy et al. | Jan 1997 | A |
5596214 | Endo | Jan 1997 | A |
5602418 | Imai et al. | Feb 1997 | A |
5603764 | Matsuda et al. | Feb 1997 | A |
5606184 | Abrokwah et al. | Feb 1997 | A |
5608046 | Cook et al. | Mar 1997 | A |
5610744 | Ho et al. | Mar 1997 | A |
5614739 | Abrokwah et al. | Mar 1997 | A |
5619051 | Endo | Apr 1997 | A |
5621227 | Joshi | Apr 1997 | A |
5623439 | Gotoh et al. | Apr 1997 | A |
5623552 | Lane | Apr 1997 | A |
5629534 | Inuzuka et al. | May 1997 | A |
5633724 | King et al. | May 1997 | A |
5635433 | Sengupta | Jun 1997 | A |
5635453 | Pique et al. | Jun 1997 | A |
5640267 | May et al. | Jun 1997 | A |
5642371 | Tohyama et al. | Jun 1997 | A |
5650646 | Summerfelt | Jul 1997 | A |
5656382 | Nashimoto | Aug 1997 | A |
5659180 | Shen et al. | Aug 1997 | A |
5661112 | Hatta et al. | Aug 1997 | A |
5666376 | Cheng | Sep 1997 | A |
5667586 | Ek et al. | Sep 1997 | A |
5668048 | Kondo et al. | Sep 1997 | A |
5670798 | Schetzina | Sep 1997 | A |
5670800 | Nakao et al. | Sep 1997 | A |
5674366 | Hayashi et al. | Oct 1997 | A |
5674813 | Nakamura et al. | Oct 1997 | A |
5679947 | Doi et al. | Oct 1997 | A |
5679965 | Schetzina | Oct 1997 | A |
5682046 | Takahashi et al. | Oct 1997 | A |
5684302 | Wersing et al. | Nov 1997 | A |
5686741 | Ohori et al. | Nov 1997 | A |
5689123 | Major et al. | Nov 1997 | A |
5693140 | McKee et al. | Dec 1997 | A |
5696392 | Char et al. | Dec 1997 | A |
5719417 | Roeder et al. | Feb 1998 | A |
5725641 | MacLeod | Mar 1998 | A |
5729394 | Sevier et al. | Mar 1998 | A |
5729641 | Chandonnet et al. | Mar 1998 | A |
5731220 | Tsu et al. | Mar 1998 | A |
5733641 | Fork et al. | Mar 1998 | A |
5734672 | McMinn et al. | Mar 1998 | A |
5735949 | Mantl et al. | Apr 1998 | A |
5741724 | Ramdani et al. | Apr 1998 | A |
5745631 | Reinker | Apr 1998 | A |
5753300 | Wessels et al. | May 1998 | A |
5753928 | Krause | May 1998 | A |
5753934 | Yano et al. | May 1998 | A |
5754319 | Van De Voorde et al. | May 1998 | A |
5754714 | Suzuki et al. | May 1998 | A |
5760426 | Marx et al. | Jun 1998 | A |
5760427 | Onda | Jun 1998 | A |
5760740 | Blodgett | Jun 1998 | A |
5764676 | Paoli et al. | Jun 1998 | A |
5767543 | Ooms et al. | Jun 1998 | A |
5770887 | Tadatomo et al. | Jun 1998 | A |
5772758 | Collins et al. | Jun 1998 | A |
5776359 | Schultz et al. | Jul 1998 | A |
5776621 | Nashimoto | Jul 1998 | A |
5777350 | Nakamura et al. | Jul 1998 | A |
5777762 | Yamamoto | Jul 1998 | A |
5778018 | Yoshikawa et al. | Jul 1998 | A |
5778116 | Tomich | Jul 1998 | A |
5780311 | Beasom et al. | Jul 1998 | A |
5789733 | Jachimowicz et al. | Aug 1998 | A |
5789845 | Wadaka et al. | Aug 1998 | A |
5790583 | Ho | Aug 1998 | A |
5792569 | Sun et al. | Aug 1998 | A |
5792679 | Nakato | Aug 1998 | A |
5796648 | Kawakubo et al. | Aug 1998 | A |
5801072 | Barber | Sep 1998 | A |
5801105 | Yano et al. | Sep 1998 | A |
5807440 | Kubota et al. | Sep 1998 | A |
5810923 | Yano et al. | Sep 1998 | A |
5812272 | King et al. | Sep 1998 | A |
5814583 | Itozaki et al. | Sep 1998 | A |
5825055 | Summerfelt | Oct 1998 | A |
5825799 | Ho et al. | Oct 1998 | A |
5827755 | Yonchara et al. | Oct 1998 | A |
5828080 | Yano et al. | Oct 1998 | A |
5830270 | McKee et al. | Nov 1998 | A |
5831960 | Jiang et al. | Nov 1998 | A |
5833603 | Kovacs et al. | Nov 1998 | A |
5834362 | Miyagaki et al. | Nov 1998 | A |
5838035 | Ramesh | Nov 1998 | A |
5838053 | Bevan et al. | Nov 1998 | A |
5844260 | Ohori | Dec 1998 | A |
5846846 | Suh et al. | Dec 1998 | A |
5852687 | Wickham | Dec 1998 | A |
5857049 | Beranek et al. | Jan 1999 | A |
5858814 | Goossen et al. | Jan 1999 | A |
5861966 | Ortel | Jan 1999 | A |
5863326 | Nause et al. | Jan 1999 | A |
5864171 | Yamamoto et al. | Jan 1999 | A |
5869845 | Vander Wagt et al. | Feb 1999 | A |
5872493 | Ella | Feb 1999 | A |
5873977 | Desu et al. | Feb 1999 | A |
5874860 | Brunel et al. | Feb 1999 | A |
5878175 | Sonoda et al. | Mar 1999 | A |
5879956 | Seon et al. | Mar 1999 | A |
5880452 | Plesko | Mar 1999 | A |
5882948 | Jewell | Mar 1999 | A |
5883564 | Partin | Mar 1999 | A |
5883996 | Knapp et al. | Mar 1999 | A |
5886867 | Chivukula et al. | Mar 1999 | A |
5888296 | Ooms et al. | Mar 1999 | A |
5889296 | Imamura et al. | Mar 1999 | A |
5896476 | Wisseman et al. | Apr 1999 | A |
5905571 | Butler et al. | May 1999 | A |
5907792 | Droopad et al. | May 1999 | A |
5912068 | Jia | Jun 1999 | A |
5919515 | Yano et al. | Jul 1999 | A |
5919522 | Baum et al. | Jul 1999 | A |
5926493 | O'Brien et al. | Jul 1999 | A |
5926496 | Ho et al. | Jul 1999 | A |
5937115 | Domash | Aug 1999 | A |
5937274 | Kondow et al. | Aug 1999 | A |
5937285 | Abrokwah et al. | Aug 1999 | A |
5948161 | Kizuki | Sep 1999 | A |
5953468 | Finnila et al. | Sep 1999 | A |
5955591 | Imbach et al. | Sep 1999 | A |
5959308 | Shichijo et al. | Sep 1999 | A |
5959879 | Koo | Sep 1999 | A |
5962069 | Schindler et al. | Oct 1999 | A |
5963291 | Wu et al. | Oct 1999 | A |
5966323 | Chen et al. | Oct 1999 | A |
5976953 | Zavracky et al. | Nov 1999 | A |
5977567 | Verdiell | Nov 1999 | A |
5981400 | Lo | Nov 1999 | A |
5981976 | Murasato | Nov 1999 | A |
5981980 | Miyajima et al. | Nov 1999 | A |
5984190 | Nevill | Nov 1999 | A |
5985404 | Yano et al. | Nov 1999 | A |
5986301 | Fukushima et al. | Nov 1999 | A |
5987011 | Toh | Nov 1999 | A |
5987196 | Noble | Nov 1999 | A |
5990495 | Ohba | Nov 1999 | A |
5995359 | Klee et al. | Nov 1999 | A |
5995528 | Fukunaga et al. | Nov 1999 | A |
5997638 | Copel et al. | Dec 1999 | A |
5998781 | Vawter et al. | Dec 1999 | A |
5998819 | Yokoyama et al. | Dec 1999 | A |
6002375 | Corman et al. | Dec 1999 | A |
6008762 | Nghiem | Dec 1999 | A |
6011641 | Shin et al. | Jan 2000 | A |
6011646 | Mirkarimi et al. | Jan 2000 | A |
6013553 | Wallace et al. | Jan 2000 | A |
6020222 | Wollesen | Feb 2000 | A |
6022140 | Fraden et al. | Feb 2000 | A |
6022410 | Yu et al. | Feb 2000 | A |
6022671 | Binkley et al. | Feb 2000 | A |
6022963 | McGall et al. | Feb 2000 | A |
6023082 | McKee et al. | Feb 2000 | A |
6028853 | Haartsen | Feb 2000 | A |
6039803 | Fitzgerald et al. | Mar 2000 | A |
6045626 | Yano et al. | Apr 2000 | A |
6046464 | Schetzina | Apr 2000 | A |
6048751 | D'Asaro et al. | Apr 2000 | A |
6049110 | Koh | Apr 2000 | A |
6049702 | Tham et al. | Apr 2000 | A |
6051858 | Uchida et al. | Apr 2000 | A |
6051874 | Masuda | Apr 2000 | A |
6055179 | Koganei et al. | Apr 2000 | A |
6058131 | Pan | May 2000 | A |
6059895 | Chu et al. | May 2000 | A |
6064078 | Northrup et al. | May 2000 | A |
6064092 | Park | May 2000 | A |
6064783 | Congdon et al. | May 2000 | A |
6078717 | Nashimoto et al. | Jun 2000 | A |
6080378 | Yokota et al. | Jun 2000 | A |
6083697 | Beecher et al. | Jul 2000 | A |
6087681 | Shakuda | Jul 2000 | A |
6088216 | Laibowitz et al. | Jul 2000 | A |
6090659 | Laibowitz et al. | Jul 2000 | A |
6093302 | Montgomery | Jul 2000 | A |
6096584 | Ellis-Monaghan et al. | Aug 2000 | A |
6100578 | Suzuki | Aug 2000 | A |
6103008 | McKee et al. | Aug 2000 | A |
6103403 | Grigorian et al. | Aug 2000 | A |
6107653 | Fitzgerald | Aug 2000 | A |
6107721 | Lakin | Aug 2000 | A |
6108125 | Yano | Aug 2000 | A |
6110813 | Ota et al. | Aug 2000 | A |
6110840 | Yu | Aug 2000 | A |
6113225 | Miyata et al. | Sep 2000 | A |
6113690 | Yu et al. | Sep 2000 | A |
6114996 | Nghiem | Sep 2000 | A |
6121642 | Newns | Sep 2000 | A |
6121647 | Yano et al. | Sep 2000 | A |
6128178 | Newns | Oct 2000 | A |
6134114 | Ungermann et al. | Oct 2000 | A |
6136666 | So | Oct 2000 | A |
6137603 | Henmi | Oct 2000 | A |
6139483 | Seabaugh et al. | Oct 2000 | A |
6140746 | Miyashita et al. | Oct 2000 | A |
6143072 | McKee et al. | Nov 2000 | A |
6143366 | Lu | Nov 2000 | A |
6146906 | Inoue et al. | Nov 2000 | A |
6150239 | Goesele et al. | Nov 2000 | A |
6151240 | Suzuki | Nov 2000 | A |
6153010 | Kiyoku et al. | Nov 2000 | A |
6153454 | Krivokapic | Nov 2000 | A |
6156581 | Vaudo et al. | Dec 2000 | A |
6173474 | Conrad | Jan 2001 | B1 |
6174755 | Manning | Jan 2001 | B1 |
6175497 | Tseng et al. | Jan 2001 | B1 |
6175555 | Hoole | Jan 2001 | B1 |
6180252 | Farrell et al. | Jan 2001 | B1 |
6180486 | Leobandung et al. | Jan 2001 | B1 |
6181920 | Dent et al. | Jan 2001 | B1 |
6184044 | Sone et al. | Feb 2001 | B1 |
6184144 | Lo | Feb 2001 | B1 |
6191011 | Gilboa et al. | Feb 2001 | B1 |
6194753 | Seon et al. | Feb 2001 | B1 |
6197503 | Vo-Dinh et al. | Mar 2001 | B1 |
6198119 | Nabatame et al. | Mar 2001 | B1 |
6204525 | Sakurai et al. | Mar 2001 | B1 |
6204737 | Ella | Mar 2001 | B1 |
6208453 | Wessels et al. | Mar 2001 | B1 |
6210988 | Howe et al. | Apr 2001 | B1 |
6211096 | Allman et al. | Apr 2001 | B1 |
6222654 | Frigo | Apr 2001 | B1 |
6224669 | Yi et al. | May 2001 | B1 |
6225051 | Sugiyama et al. | May 2001 | B1 |
6229159 | Suzuki | May 2001 | B1 |
6232242 | Hata et al. | May 2001 | B1 |
6232806 | Woeste et al. | May 2001 | B1 |
6232910 | Bell et al. | May 2001 | B1 |
6233435 | Wong | May 2001 | B1 |
6235145 | Li et al. | May 2001 | B1 |
6235649 | Kawahara et al. | May 2001 | B1 |
6238946 | Ziegler | May 2001 | B1 |
6239012 | Kinsman | May 2001 | B1 |
6239449 | Fafard et al. | May 2001 | B1 |
6241821 | Yu et al. | Jun 2001 | B1 |
6242686 | Kishimoto et al. | Jun 2001 | B1 |
6248459 | Wang et al. | Jun 2001 | B1 |
6248621 | Wilk et al. | Jun 2001 | B1 |
6252261 | Usui et al. | Jun 2001 | B1 |
6255198 | Linthicum et al. | Jul 2001 | B1 |
6256426 | Duchet | Jul 2001 | B1 |
6265749 | Gardner et al. | Jul 2001 | B1 |
6268269 | Lee et al. | Jul 2001 | B1 |
6271619 | Yamada et al. | Aug 2001 | B1 |
6275122 | Speidell et al. | Aug 2001 | B1 |
6277436 | Stauf et al. | Aug 2001 | B1 |
6278137 | Shimoyama et al. | Aug 2001 | B1 |
6278138 | Suzuki | Aug 2001 | B1 |
6278523 | Gorecki | Aug 2001 | B1 |
6278541 | Baker | Aug 2001 | B1 |
6291319 | Yu et al. | Sep 2001 | B1 |
6291866 | Wallace | Sep 2001 | B1 |
6297598 | Wang et al. | Oct 2001 | B1 |
6297842 | Koizumi et al. | Oct 2001 | B1 |
6300615 | Shinohara et al. | Oct 2001 | B1 |
6306668 | McKee et al. | Oct 2001 | B1 |
6307996 | Nashimoto et al. | Oct 2001 | B1 |
6312819 | Jia et al. | Nov 2001 | B1 |
6313486 | Kencke et al. | Nov 2001 | B1 |
6316785 | Nunoue et al. | Nov 2001 | B1 |
6316832 | Tsuzuki et al. | Nov 2001 | B1 |
6319730 | Ramdani et al. | Nov 2001 | B1 |
6320238 | Kizilyalli et al. | Nov 2001 | B1 |
6326637 | Parkin et al. | Dec 2001 | B1 |
6326645 | Kadota | Dec 2001 | B1 |
6326667 | Sugiyama et al. | Dec 2001 | B1 |
6329277 | Liu et al. | Dec 2001 | B1 |
6338756 | Dietze | Jan 2002 | B1 |
6339664 | Farjady et al. | Jan 2002 | B1 |
6340788 | King et al. | Jan 2002 | B1 |
6341851 | Takayama et al. | Jan 2002 | B1 |
6343171 | Yoshimura et al. | Jan 2002 | B1 |
6345424 | Hasegawa et al. | Feb 2002 | B1 |
6348373 | Ma et al. | Feb 2002 | B1 |
6355945 | Kadota et al. | Mar 2002 | B1 |
6359330 | Goudard | Mar 2002 | B1 |
6362017 | Manabe et al. | Mar 2002 | B1 |
6362558 | Fukui | Mar 2002 | B1 |
6367699 | Ackley | Apr 2002 | B1 |
6372356 | Thornton et al. | Apr 2002 | B1 |
6372813 | Johnson et al. | Apr 2002 | B1 |
6376337 | Wang et al. | Apr 2002 | B1 |
6389209 | Suhir | May 2002 | B1 |
6391674 | Ziegler | May 2002 | B1 |
6392253 | Saxena | May 2002 | B1 |
6392257 | Ramdani et al. | May 2002 | B1 |
6393167 | Davis et al. | May 2002 | B1 |
6404027 | Hong et al. | Jun 2002 | B1 |
6410941 | Taylor et al. | Jun 2002 | B1 |
6410947 | Wada | Jun 2002 | B1 |
6411756 | Sadot et al. | Jun 2002 | B1 |
6415140 | Benjamin et al. | Jul 2002 | B1 |
6417059 | Huang | Jul 2002 | B1 |
6419849 | Qiu et al. | Jul 2002 | B1 |
6427066 | Grube | Jul 2002 | B1 |
6432546 | Ramesh et al. | Aug 2002 | B1 |
6438281 | Tsukamoto et al. | Aug 2002 | B1 |
6445724 | Abeles | Sep 2002 | B1 |
6452232 | Adan | Sep 2002 | B1 |
6461927 | Mochizuki et al. | Oct 2002 | B1 |
6462360 | Higgins, Jr. et al. | Oct 2002 | B1 |
6477285 | Shanley | Nov 2002 | B1 |
6496469 | Uchizaki | Dec 2002 | B1 |
6498358 | Lach et al. | Dec 2002 | B1 |
6501121 | Yu et al. | Dec 2002 | B1 |
6504189 | Matsuda et al. | Jan 2003 | B1 |
6524651 | Gan et al. | Feb 2003 | B1 |
6528374 | Bojarczuk, Jr. et al. | Mar 2003 | B1 |
6538359 | Hiraku et al. | Mar 2003 | B1 |
6589887 | Dalton et al. | Jul 2003 | B1 |
20010013313 | Droopad et al. | Aug 2001 | A1 |
20010020278 | Saito | Sep 2001 | A1 |
20010036142 | Kadowaki et al. | Nov 2001 | A1 |
20010055820 | Sakurai et al. | Dec 2001 | A1 |
20020006245 | Kubota et al. | Jan 2002 | A1 |
20020008234 | Emrick | Jan 2002 | A1 |
20020021855 | Kim | Feb 2002 | A1 |
20020030246 | Eisenbeiser et al. | Mar 2002 | A1 |
20020047123 | Ramdani et al. | Apr 2002 | A1 |
20020047143 | Ramdani et al. | Apr 2002 | A1 |
20020052061 | Fitzgerald | May 2002 | A1 |
20020072245 | Ooms et al. | Jun 2002 | A1 |
20020076878 | Wasa et al. | Jun 2002 | A1 |
20020079576 | Seshan | Jun 2002 | A1 |
20020131675 | Litvin | Sep 2002 | A1 |
20020140012 | Droopad | Oct 2002 | A1 |
20020145168 | Bojarczuk, Jr. et al. | Oct 2002 | A1 |
20020179000 | Lee et al. | Dec 2002 | A1 |
20020195610 | Klosowiak | Dec 2002 | A1 |
Number | Date | Country |
---|---|---|
196 07 107 | Aug 1997 | DE |
197 12 496 | Oct 1997 | DE |
198 29 609 | Jan 2000 | DE |
100 17 137 | Oct 2000 | DE |
0 247 722 | Dec 1987 | EP |
0 250 171 | Dec 1987 | EP |
0 300 499 | Jan 1989 | EP |
0 309 270 | Mar 1989 | EP |
0 331 338 | Sep 1989 | EP |
0 331 467 | Sep 1989 | EP |
0 342 937 | Nov 1989 | EP |
0 392 714 | Oct 1990 | EP |
0 412 002 | Feb 1991 | EP |
0 455 526 | Jun 1991 | EP |
0 483 993 | May 1992 | EP |
0 494 514 | Jul 1992 | EP |
0 514 018 | Nov 1992 | EP |
0 538 611 | Apr 1993 | EP |
0 581 239 | Feb 1994 | EP |
0 600 658 | Jun 1994 | EP |
0 602 568 | Jun 1994 | EP |
0 607 435 | Jul 1994 | EP |
0 614 256 | Sep 1994 | EP |
0 619 283 | Oct 1994 | EP |
0 630 057 | Dec 1994 | EP |
0 661 561 | Jul 1995 | EP |
0 860 913 | Aug 1995 | EP |
0 682 266 | Nov 1995 | EP |
0 711 853 | May 1996 | EP |
0 766 292 | Apr 1997 | EP |
0 777 379 | Jun 1997 | EP |
0 810 666 | Dec 1997 | EP |
0 828 287 | Mar 1998 | EP |
0 852 416 | Jul 1998 | EP |
0 875 922 | Nov 1998 | EP |
0 881 669 | Dec 1998 | EP |
0 884 767 | Dec 1998 | EP |
0 926 739 | Jun 1999 | EP |
0 957 522 | Nov 1999 | EP |
0 964 259 | Dec 1999 | EP |
0 964 453 | Dec 1999 | EP |
0 993 027 | Apr 2000 | EP |
0 999 600 | May 2000 | EP |
1 001 468 | May 2000 | EP |
1 035 759 | Sep 2000 | EP |
1 037 272 | Sep 2000 | EP |
1 043 426 | Oct 2000 | EP |
1 043 427 | Oct 2000 | EP |
1 043 765 | Oct 2000 | EP |
1 054 442 | Nov 2000 | EP |
1 069 605 | Jan 2001 | EP |
1 069 606 | Jan 2001 | EP |
1 085 319 | Mar 2001 | EP |
1 089 338 | Apr 2001 | EP |
1 109 212 | Jun 2001 | EP |
1 176 230 | Jan 2002 | EP |
2 779 843 | Dec 1999 | FR |
1 319 311 | Jun 1970 | GB |
2 152 315 | Jul 1985 | GB |
2 335 792 | Sep 1999 | GB |
52-88354 | Jul 1977 | JP |
52-89070 | Jul 1977 | JP |
52-135684 | Nov 1977 | JP |
54-134554 | Oct 1979 | JP |
55-87424 | Jul 1980 | JP |
58-075868 | May 1983 | JP |
58-213412 | Dec 1983 | JP |
59-044004 | Mar 1984 | JP |
59-073498 | Apr 1984 | JP |
59066183 | Apr 1984 | JP |
60-161635 | Aug 1985 | JP |
60-210018 | Oct 1985 | JP |
60-212018 | Oct 1985 | JP |
61-36981 | Feb 1986 | JP |
61-63015 | Apr 1986 | JP |
61-108187 | May 1986 | JP |
62-245205 | Oct 1987 | JP |
63-34994 | Feb 1988 | JP |
63-131104 | Jun 1988 | JP |
63-198365 | Aug 1988 | JP |
63-289812 | Nov 1988 | JP |
64-50575 | Feb 1989 | JP |
64-52329 | Feb 1989 | JP |
1-102435 | Apr 1989 | JP |
1-179411 | Jul 1989 | JP |
01-196809 | Aug 1989 | JP |
03-149882 | Nov 1989 | JP |
HEI 2-391 | Jan 1990 | JP |
02051220 | Feb 1990 | JP |
3-41783 | Feb 1991 | JP |
03046384 | Feb 1991 | JP |
3-171617 | Jul 1991 | JP |
03-188619 | Aug 1991 | JP |
5-48072 | Feb 1993 | JP |
5-086477 | Apr 1993 | JP |
5-152529 | Jun 1993 | JP |
05150143 | Jun 1993 | JP |
05 221800 | Aug 1993 | JP |
5-232307 | Sep 1993 | JP |
5-238894 | Sep 1993 | JP |
5-243525 | Sep 1993 | JP |
5-291299 | Nov 1993 | JP |
06-069490 | Mar 1994 | JP |
6-232126 | Aug 1994 | JP |
6-291299 | Oct 1994 | JP |
6-334168 | Dec 1994 | JP |
0812494 | Jan 1996 | JP |
9-67193 | Mar 1997 | JP |
9-82913 | Mar 1997 | JP |
10-256154 | Sep 1998 | JP |
10-269842 | Oct 1998 | JP |
10-303396 | Nov 1998 | JP |
10-321943 | Dec 1998 | JP |
11135614 | May 1999 | JP |
11-238683 | Aug 1999 | JP |
11-260835 | Sep 1999 | JP |
01 294594 | Nov 1999 | JP |
11340542 | Dec 1999 | JP |
2000-068466 | Mar 2000 | JP |
2 000 1645 | Jun 2000 | JP |
2000-278085 | Oct 2000 | JP |
2000-349278 | Dec 2000 | JP |
2000-351692 | Dec 2000 | JP |
2001-196892 | Jul 2001 | JP |
2002-9366 | Jan 2002 | JP |
WO 9210875 | Jun 1992 | WO |
WO 9307647 | Apr 1993 | WO |
WO 9403908 | Feb 1994 | WO |
WO 9502904 | Jan 1995 | WO |
WO 9745827 | Dec 1997 | WO |
WO 9805807 | Jan 1998 | WO |
WO 9820606 | May 1998 | WO |
WO 9914797 | Mar 1999 | WO |
WO 9914804 | Mar 1999 | WO |
WO 9919546 | Apr 1999 | WO |
WO 9963580 | Dec 1999 | WO |
WO 9967882 | Dec 1999 | WO |
WO 0006812 | Feb 2000 | WO |
WO 0016378 | Mar 2000 | WO |
WO 0033363 | Jun 2000 | WO |
WO 0048239 | Aug 2000 | WO |
WO 0104943 | Jan 2001 | WO |
WO 0116395 | Mar 2001 | WO |
WO 0133585 | May 2001 | WO |
WO 0137330 | May 2001 | WO |
WO 0159814 | Aug 2001 | WO |
WO 0159820 | Aug 2001 | WO |
WO 0159821 | Aug 2001 | WO |
WO 0159837 | Aug 2001 | WO |
WO 02 01648 | Jan 2002 | WO |
WO 0203113 | Jan 2002 | WO |
WO 0203467 | Jan 2002 | WO |
WO 0203480 | Jan 2002 | WO |
WO 0208806 | Jan 2002 | WO |
WO 02009150 | Jan 2002 | WO |
WO 0209160 | Jan 2002 | WO |
WO 0211254 | Feb 2002 | WO |
WO 0233385 | Apr 2002 | WO |
WO 0247127 | Jun 2002 | WO |
WO 0250879 | Jun 2002 | WO |
WO 02099885 | Dec 2002 | WO |
WO 03012874 | Feb 2003 | WO |
Number | Date | Country | |
---|---|---|---|
20040149203 A1 | Aug 2004 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 10076450 | Feb 2002 | US |
Child | 10768108 | US | |
Parent | 09502023 | Feb 2000 | US |
Child | 10076450 | US |