JP2012015531A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device such as a MOSFET for high-frequency amplification having a drain offset region which ensures refinement and reduces on-resistance.SOLUTION: The semiconductor device comprises a source region 10, a drain region 9 and conductor plugs 13 (p1) on a reach-through layer 3 (4) for leading out electrodes. First layer wires 11s, 11d (M1) are respectively connected to the conductor plugs 13 (p1), and second layer wires 12s, 12d for backing the first layer wires 11s, 11d (M1) are connected to the first layer wires 11s, 11d (M1), respectively, on the conductor plugs 13 (p1).

Description

  The present invention relates to a semiconductor device used in a mobile communication device using a microwave band of 500 MHz or more and 2.5 GHz or less such as cellular, and is particularly effective for a high frequency power amplifier that amplifies and outputs a high frequency signal. Technology.

  In recent years, mobile communication devices represented by GSM (Global System for Mobile Communications) system, PCS (Personal Communication Systems) system, PDC (Personal Digital Cellular) system, CDMA (Code Division Multiple Access) system, etc. Phone) is widespread worldwide.

  In general, a mobile communication device includes an antenna that emits and receives radio waves, a high-frequency power amplifier that amplifies a power-modulated high-frequency signal and supplies the signal to the antenna, a receiving unit that processes the high-frequency signal received by the antenna, It comprises a control unit that performs control, and a battery that supplies a power supply voltage thereto.

  Such mobile communication devices and semiconductor devices used in the mobile communication devices are disclosed in the following publicly known documents.

  (1) The configuration of the mobile communication device is disclosed in, for example, “Hitachi Review”, vol. 78, No. 11 (1996-11), pp 21-26 (Non-patent Document 1).

  (2) The structure of a typical GSM type high frequency power amplifier is described in, for example, ISSCC98, DIGEST OF TECHNICAL PAPERS (February 5, 1998) pp50-52 (Non-patent Document 2).

  According to this document, the threshold voltage of the FET is controlled to an appropriate value in order to stably design the circuit and reduce the leakage current in the off state. As a configuration of the amplifier, the final stage element of the three-stage amplifier circuit is arranged in parallel in two chips, and a matching circuit is provided for each of them to combine them, thereby realizing higher output than in the case of one chip. In the literature, this amplifier configuration is called DD-CIMA (Divided Device and Collectively Impedance matched Amplifier) technology.

  (3) The amplifying element applied to the high frequency power amplifier is described in, for example, IEDM97 Technical Digest (1997), pp51-54 (Non-patent Document 3).

  According to this document, it is disclosed that the amplifying element is configured by a power insulated gate field effect transistor (hereinafter referred to as a power MOSFET) using a Si (silicon) semiconductor to realize high performance.

  Specifically, the performance is improved by setting the gate length of the MOSFET to 0.4 μm. Further, the drain breakdown voltage is set to 20 V or more by providing an offset layer having a length of about 0.7 μm on the drain side of the power MOSFET. Furthermore, reduction of gate resistance is important for high-frequency operation, and gate resistance is reduced by a structure in which an aluminum wiring is short-circuited to a metal silicide / silicon laminated gate electrode (Al-shorted silicon gate structure). .

  (4) There is a movement to adopt compound semiconductor (GaAs) wafers for higher device efficiency. Such technical trends are described in, for example, NIKKEI ELECTRONICS 1998.11.2 (no. 729) pp238-245 (Non-Patent Document 4). However, as described in this document, the wafer unit price of GaAs technology is higher than that of Si.

"Hitachi review", vol.78, No.11 (1996-11), pp21-26 ISSCC98, DIGEST OF TECHNICAL PAPERS (February 5, 1998) pp50-52 IEDM97 Technical Digest (1997), pp51-54 NIKKEI ELECTRONICS 1998.11.2 (no.729) pp238-245

  In order to promote the spread of mobile communication devices, there is a demand for further reduction in size and weight of the devices and reduction in power consumption. Therefore, it is necessary to further reduce the size and weight and reduce the power consumption of each component constituting the mobile communication device.

  One of the components is a high frequency power amplifier that supplies a high frequency signal to an antenna. In general, this high-frequency power amplifier consumes the largest amount of power, and in order to reduce the power consumption of the mobile communication device, it is effective to pursue the reduction (improvement in efficiency) of the power consumption of this high-frequency power amplifier. A GSM amplifier using a silicon (Si) semiconductor, realizing an output voltage of 3.5 W and an overall efficiency (ηall) of about 50% at an operating frequency of 900 MHz and a power supply voltage of 3.5 V. The total efficiency here refers to the efficiency of a high-frequency power amplifier (high-frequency module) configured from a power amplification unit of three stages of power MOSFETs.

  At this time, the performance of the power MOSFET using Si as the output stage amplifying element is about 55% additional efficiency (ηadd) at 2 W output, assuming the DD-CIMA technology, and the total efficiency of the amplifier is 55% or more. In order to improve the power MOSFET, an additional efficiency of 65% or more must be realized in the power MOSFET.

  For the definition of added efficiency (ηadd) in microwave power MOSFET, see “Optical Microwave Semiconductor Application Technology” February 29, 1996, 1st edition, 1st edition (published by Science Forum, Inc.) pp59-66 (Reference 5).

  Similarly, the PCS amplifier achieves an output voltage of 2 W and an overall efficiency of about 45% at an operating frequency of 1900 MHz. At this time, the performance of the power MOSFET as the output stage amplifying element is about 50% at 1 W output. In order to improve the overall efficiency of the amplifier to 50% or more, it was necessary to realize an additional efficiency of 55% or more in the power MOSFET.

  In order to improve the additional efficiency of the amplifying element (power MOSFET), reduction of on-resistance, gate resistance, parasitic capacitance, and improvement of transconductance can be mentioned.

  An object of the present invention is to provide a technique for achieving high added efficiency of a semiconductor device applied to a high frequency amplifier.

  A specific object of the present invention is to provide a technique for reducing the on-resistance of a semiconductor device.

  Another specific object of the present invention is to provide a technique for improving the cutoff frequency.

  Another object of the present invention is to realize a semiconductor device that achieves both improvement in added efficiency in high-frequency and high-power operation, and ensuring of reliability and mass productivity. Still another object of the present invention is to provide a technique for reducing the size and weight of a high-frequency power amplifier.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  One representative semiconductor device configuration of the present invention includes a first conductivity type semiconductor substrate, a first conductivity type semiconductor layer formed on an upper surface of the semiconductor substrate, and a part of a main surface of the semiconductor layer. The first and second regions of the second conductivity type opposite to the first conductivity type, which are located apart from each other across the region where the channel is formed, and the second region is a region where the channel is formed A gate electrode formed on the channel region via a gate insulating film, a first region on the other main surface of the semiconductor layer, and a high concentration region in contact with the low concentration region. A first through-type reach through layer formed in contact with the semiconductor substrate; a first insulating film covering the gate electrode, the first region, the second region, and the reach through layer; The above through the opening provided in the insulating film Connected to the first conductor plug, the second conductor plug, the third conductor plug, and the first conductor plug and the third plug, respectively, connected to one region, the high concentration region of the second region, and the reach through layer. The first conductor layer is formed, the second conductor layer connected to the second conductor plug, and the third conductor layer connected to the lower surface of the semiconductor substrate.

  According to the above-described means, since the conductor plug is used for electrode extraction of the high concentration region of the first region (source), the second region (drain) and the reach-through layer (source punching layer), The first and second conductor layers (first layer wiring M1) constitute an electrode pattern having a flat surface. For this reason, the arrangement of the backing wiring layer (second layer wiring M2) and the degree of freedom of the M1 and M2 contacts for realizing the low resistance wiring with respect to the first and second conductor layers are increased.

  Therefore, it is possible to reduce the wiring resistance with respect to the first region, the high concentration region of the second region, and the reach through layer. As a result, the on-resistance can be reduced, which can contribute to high added efficiency of the semiconductor device.

  Another typical semiconductor device configuration of the present invention is an insulated gate field effect semiconductor device having a P-type semiconductor region and a drain offset region in contact with the P-type semiconductor region, wherein the gate electrode in contact with the gate insulating film is P An N-type layer is provided on the surface of the P-type semiconductor region.

  According to the above-described means, the threshold voltage Vth is increased by 1 V due to the work function difference as compared with the N gate (the gate electrode is an N type semiconductor) because the gate electrode is a P type semiconductor, that is, a P gate. become. For this reason, normally-off, that is, an enhancement state can be maintained in a state where no gate voltage is applied even though an N-type layer is provided on the surface of the P-type semiconductor region. The presence of the N-type layer brings about an action of extending the depletion layer extending from the drain junction, and the drain breakdown voltage is improved. Therefore, when designing a P gate device (P gate power MOSFET) having the same drain breakdown voltage as that of the N gate, the concentration of the drain offset region can be increased. That is, it is not necessary to extend the depletion layer to the drain offset region side. The fact that the concentration of the offset region can be increased means that the resistance of the drain offset region can be reduced as compared with the N gate device.

  In addition, the presence of the N-type layer causes electric field relaxation on the surface of the channel region. Therefore, carrier mobility in the channel region portion is improved. It can be considered that the improvement in carrier mobility is that the resistance component in that portion is reduced.

  Further, the improvement in carrier mobility based on the above configuration allows a large amount of current to flow even if the gate length Lg is shortened. That is, normally, when the gate length is shortened, the carrier velocity is remarkably saturated and it becomes difficult to flow a large current.

  As a result of the above, when the on-resistances of the P gate device and the N gate device at the same breakdown voltage are compared, the P gate device can be sufficiently reduced as compared with the N gate device. That is, the P gate power MOSFET can achieve high added efficiency.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve additional efficiency, ensuring the output power and destruction tolerance of power MOSFET used for portable telephone terminals, such as GSM, PCS, PDC, and CDMA systems. In the GSM system module using this, it becomes possible to achieve an output power of 4 W and an overall efficiency of 55%. Further, the module mounting area can be reduced by downsizing and integration of the chip.

1 is a cross-sectional view of a semiconductor device (N-gate / N-channel Si power MOSFET) according to a first embodiment of the present invention. It is a top view of the semiconductor device which is Embodiment 1 of this invention. It is a top view which shows the layout of the semiconductor device (semiconductor chip) which is Embodiment 1 of this invention. FIG. 4 is an enlarged partial plan view of a protection element 19 in the semiconductor device (semiconductor chip) shown in FIG. 3. FIG. 5 is a cross-sectional view of a DD ′ cut portion of the protection element shown in FIG. 4. It is principal part sectional drawing in the manufacturing process of the semiconductor device which is Embodiment 1 of this invention. FIG. 7 is a fragmentary cross-sectional view of the semiconductor device during a manufacturing step following that of FIG. 6; FIG. 8 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 7; FIG. 9 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 8; FIG. 10 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 9; FIG. 11 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 10; FIG. 12 is a fragmentary cross-sectional view of the semiconductor device during a manufacturing step following that of FIG. 11; FIG. 13 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 12; FIG. 14 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 13; FIG. 15 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 14; FIG. 16 is a fragmentary cross-sectional view of the semiconductor device during a manufacturing step following that of FIG. 15; FIG. 17 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 16; FIG. 18 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 17; FIG. 19 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 18; FIG. 20 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 19; FIG. 21 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 20; FIG. 22 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 21; FIG. 23 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 22; FIG. 24 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 23; FIG. 25 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 24; FIG. 26 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 25; FIG. 27 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 26; FIG. 28 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 27; FIG. 29 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 28; 1 is an equivalent circuit diagram of a semiconductor device according to a first embodiment of the present invention. It is a characteristic view which shows the relationship between the gate oxide film thickness in the semiconductor device which is Embodiment 1 of this invention, ON resistance, and a gate pressure | voltage resistance. It is a characteristic view which shows the relationship between the gate length and on-resistance in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the gate length and mutual conductance in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the gate length and threshold voltage in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the offset layer depth and on-resistance in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between offset length and on-resistance in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the offset length and drain breakdown voltage in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the punch through stopper layer position and on-resistance in the semiconductor device which is Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the punch through stopper layer position in the semiconductor device which is Embodiment 1 of this invention, and a drain proof pressure. FIG. 2 is an impurity concentration distribution diagram of a B-B ′ cut portion in the semiconductor device shown in FIG. 1. It is a characteristic view which shows the resistivity dependence of the board | substrate punching layer in the epitaxial layer thickness of the semiconductor device which is Embodiment 1 of this invention. FIG. 2 is an impurity concentration distribution diagram of a C-C ′ cut portion in the semiconductor device shown in FIG. 1. It is a characteristic view which shows the relationship between the epitaxial layer thickness and breakdown voltage in the semiconductor device which is Embodiment 1 of this invention. FIG. 3 is a current-voltage characteristic diagram of the semiconductor device according to the first embodiment of the present invention. It is a top view which shows the contact part of the drain wiring of a prior art. It is a top view which shows the contact part of the drain wiring of the semiconductor device which is Embodiment 1 of this invention. It is RF characteristic view of the semiconductor device which is Embodiment 1 of the present invention. FIG. 6 is an RF characteristic diagram (dependent on gate width Wg) of the semiconductor device according to the first embodiment of the present invention; 2 is an equivalent circuit of an RF power module using the semiconductor device according to the first embodiment of the present invention. It is a top view which shows the layout of RF power module using the semiconductor device which is Embodiment 1 of this invention. It is sectional drawing of the semiconductor device which is Embodiment 2 of this invention. It is a characteristic view which shows the voltage dependence of the drain-gate capacity | capacitance of the semiconductor device which is Embodiment 2 of this invention. It is a characteristic view which shows the relationship between the signal gain and frequency of the semiconductor device which is Embodiment 2 of this invention. It is principal part sectional drawing in the manufacturing process of the semiconductor device which is Embodiment 2 of this invention. FIG. 55 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 54; It is principal part sectional drawing of the completed semiconductor device which is Embodiment 2 of this invention. It is principal part sectional drawing in the manufacturing process of the semiconductor device which is Embodiment 3 of this invention. FIG. 58 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 57; FIG. 59 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 58; It is principal part sectional drawing of the completed semiconductor device which is Embodiment 3 of this invention. It is principal part sectional drawing of the semiconductor device which is Embodiment 4 of this invention. It is principal part sectional drawing of the semiconductor device which is Embodiment 5 of this invention. It is a figure which shows the relationship between the offset layer surface concentration of the semiconductor device which is Embodiment 5 of this invention, and ON resistance deterioration rate. It is principal part sectional drawing of the semiconductor device which is Embodiment 6 of this invention. It is principal part sectional drawing of the semiconductor device which is Embodiment 7 of this invention. It is a top view of the semiconductor device which is Embodiment 7 of this invention. It is a top view of the semiconductor device which is Embodiment 8 of this invention. It is a top view of the semiconductor device which is Embodiment 9 of this invention. It is principal part sectional drawing of the semiconductor device which is Embodiment 10 of this invention. It is a top view of the semiconductor device which is Embodiment 10 of this invention. It is a top view of the protection element in the semiconductor device (semiconductor chip) which is Embodiment 11 of this invention. FIG. 72 is a cross-sectional view taken along the line DD ′ of the protection element shown in FIG. 71. It is a top view which shows the layout of the semiconductor device (semiconductor chip) which is Embodiment 12 of this invention. It is a top view which shows the layout of the semiconductor device (semiconductor chip) which is Embodiment 13 of this invention. It is a top view which shows the layout of the semiconductor device (semiconductor chip) which is Embodiment 14 of this invention. It is principal part sectional drawing of the semiconductor device (P gate and N channel type Si power MOSFET) which is Embodiment 15 of this invention. It is principal part sectional drawing which shows extension of the depletion layer in the semiconductor device (P gate and N channel type power MOSFET) which is Embodiment 15 of this invention. It is principal part sectional drawing in the manufacturing process of the semiconductor device which is Embodiment 15 of this invention. It is principal part sectional drawing in the manufacturing process of the semiconductor device which is Embodiment 16 of this invention. FIG. 80 is an essential part cross sectional view of the semiconductor device during a manufacturing step following FIG. 79; It is principal part sectional drawing of the completed semiconductor device which is Embodiment 16 of this invention. FIG. 77 is an impurity distribution diagram of a G-G ′ cut portion of FIG. 76. It is a top view of the semiconductor device which increased the number of gates of Embodiment 1 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols in the drawings for describing the embodiments, and the repetitive description thereof is omitted.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS.

  1 is a cross-sectional view of a semiconductor device (N-gate / N-channel Si power MOSFET) according to a first embodiment of the present invention, and FIG. 2 is a plan view of the semiconductor device according to the first embodiment of the present invention. It is. FIG. 3 is a plan view showing the layout of the semiconductor device (semiconductor chip) according to the first embodiment of the present invention. FIG. 4 is an enlarged view of the protection element 19 in the semiconductor device (semiconductor chip) shown in FIG. FIG. FIG. 5 is a cross-sectional view taken along the line DD ′ of the protection element shown in FIG.

<Cross-sectional structure of basic cell>
The configuration of the semiconductor device (basic cell of MOSFET) according to the first embodiment of the present invention shown in FIG. 1 is as follows.

  A P-type high resistance Si epitaxial layer (first conductivity type semiconductor layer) 2 is formed on the upper surface of a P-type low resistance Si substrate (first conductivity type semiconductor substrate) 1. The substrate specific resistance is set to 0.02 Ωcm or less for the purpose of reducing the on-resistance. Conventionally, it is disclosed in Japanese Patent Application Laid-Open No. 6-97447 that the specific resistance of a silicon substrate applied to a power MOSFET is 0.02 Ωcm or less. The specific resistance of the silicon substrate applied to the first embodiment is 0.01 Ωcm.

  Recently, epitaxial wafers are also applied to CMOSIC, but in this case, the substrate specific resistance is about 10 Ωcm, which is about three orders of magnitude smaller than the substrate specific resistance in IC. The epitaxial layer has a specific resistance of 20 Ωcm and a thickness of 3 μm. The thickness of the epitaxial layer disclosed in the above publication is 5 μm, and is 2 μm thinner than that for the purpose of reducing the on-resistance.

  A P-type well region 5 (PW) is selectively formed as a region where a channel is formed on a part of the main surface of the epitaxial layer 2. The P-type well region is intended as a punch-through stopper for suppressing the depletion layer extending from the drain to the source. A gate electrode 7 is formed on the surface of the P-type well region 5 (PW) via a gate insulating film (gate oxide film) 6.

  An N-type source region (first region) 10 having a high impurity concentration and a low impurity concentration are formed in the epitaxial layer 2 at positions separated from each other in contact with the P-type well region 5 (punch-through stopper layer PW). An N-type drain offset region (third region) 8 (NM) is formed. These N-type source region 10 and N-type drain offset region 8 (NM) are self-aligned with respect to the gate electrode 7, and a part of them overlaps with the gate electrode 7.

  Note that the N-type (high resistance) region 8 located under the N-type source region 10 is not particularly required. The N-type (high resistance) region 8 is formed in a self-aligned manner with respect to the gate electrode 7 when an impurity is introduced to form the N-type drain offset region 8 (NM).

  An N-type drain region (second region) 9 having a high impurity concentration for extracting an electrode is formed in contact with the drain offset region 8.

  A P-type source punching layer (reach-through layer) 3 having a high impurity concentration (low resistance) reaching the substrate 1 from its main surface is formed in the epitaxial layer 2 in contact with the N-type source region 10. A contact type P-type low resistance region 4 is formed on the surface of the reach-through layer 3. The N-type source region 10 is electrically connected to the source back electrode S <b> 1 through the metal plug, the first layer wiring, the metal plug, and the reach through layer 3.

  In FIG. 1, the area between AA ′ is a basic cell, and the pitch is about 6 μm. The gate length Lg of the gate electrode 3 is 0.3 μm, and the length of the drain offset region 8 provided for securing the drain withstand voltage by electric field relaxation, that is, the drain offset length Lr is 0.7 μm. The gate oxide film thickness was 11 nm, and was set in consideration of on-resistance improvement and an oxide film allowable electric field. This will be described in detail later. A first insulating film (interlayer insulating film) 20 is formed so as to cover the gate electrode 7, the N-type source region 10, the N-type drain offset region 8 (NM), the N-type drain (low resistance) region 9 and the P-type source punching layer 3. Is formed. A plurality of openings are provided in the first insulating film 20, and in these openings, conductor plugs P1 for extracting electrodes that are in contact with the N-type source region 10, the N-type drain region 9, and the P-type source punching layer 3, respectively. Have The conductor plug P <b> 1 is made of tungsten and embedded in the opening, and its surface substantially coincides with the surface of the first insulating film 20.

  On the surface of the first insulating film 20, a first conductor layer 11 d that electrically connects the conductor plug connected to the N-type source region 10 and the conductor plug contacted to the P-type source punching layer 3 includes an N-type drain. A second conductor layer 11s connected to the conductor plug P1 in contact with the region 9 is patterned as a first layer wiring (M1).

  A second insulating film (interlayer insulating film) 30 is formed so as to cover the first and second conductor layers 11d and 11s. In the second insulating film, openings are formed on the conductor plugs in contact with the P-type source punching region 3 so as to be located at the conductor plugs P1 in contact with the N-type drain region 9. Via these openings, wirings 12d and 12s (second layer wiring M2) as backing wirings for reducing the wiring resistance are connected to the first and second conductor layers 11d and 11s, respectively.

  The source back electrode S (2) is connected to a first reference potential, for example, a ground potential, while the drain electrode 12d is a second reference potential higher than the first reference potential, for example, a power supply (Vdd = 3.6V) potential. Connected to.

<Unit block layout>
The relationship between the first layer wiring and the second layer wiring of the first embodiment will be described in detail below with reference to FIG.

  In FIG. 2, 11 is a first-layer conductor layer (first-layer wiring M1), and 12 is a second-layer conductor layer (second-layer wiring M1). Reference numeral 13 denotes a contact portion of a conductor plug (metal plug) for a semiconductor region such as the N-type source region 10, the N-type drain region 9, and the P-type source punching layer 3, and 14 denotes a second portion for the first layer wiring M1. This is a contact portion of the layer wiring M2. Reference numeral 21 denotes a boundary line of the element isolation region (field oxide film). That is, the portion surrounded by the line 21 is an element formation region. Reference numeral 22 denotes a drain electrode bonding pad (drain pad), and reference numeral 23 denotes a gate electrode bonding pad (gate pad). The drain and gate pads 22 and 23 represent one block. In an actual chip, several blocks are arranged in parallel according to the required gate width. This will be described later with reference to FIG.

  FIG. 2 shows a case where there are two gate electrodes 3, a drain region is provided between the gate electrodes 3, and both sides are source regions. Between AA ′ is the basic cell shown in FIG. 1, and in an actual chip, several blocks are arranged repeatedly to form one block. The drain is extended to the pad 22 by the second layer wiring in parallel without crossing the gate electrode 3. Further, the source is also lined with the second layer wiring in parallel without crossing the gate electrode 3. The gate is extended from the gate electrode 3 by the first layer wiring at every fixed length, and is commonly connected to the pad portion 23 by the second layer wiring from the periphery. In the case of the first embodiment, the fixed length for extracting the gate electrode is about 40 μm. Further, since the wiring is taken out perpendicular to the gate electrode, the parasitic capacitance between the drain second layer wiring and the gate first layer wiring is reduced. That is, the striped gate electrode 3 is extended by the first layer wiring 11 in a direction perpendicular to the drain wiring and the gate electrode at a constant distance of about 40 μm. The second layer wiring 12 is commonly connected to the gate pad 23 at both ends of the block. As a result, the parasitic capacitance between the drain wiring and the gate wiring is reduced as compared with the case of extending in parallel.

  In addition, the extension portion 12E of the second metal conductor layer for the source is disposed in the vicinity of the drain pad portion 22, and is located under the extension portion 12E and has the same configuration as the through layer. A through layer is provided in the epitaxial layer, and the extension portion 12E is electrically connected to the through layer.

  It should be noted here that according to the first embodiment, a conductor plug is employed as the electrode lead-out conductor, and the contact opening (contact portion) with the second-layer wiring for the first-layer wiring M1 is the electrode lead-out. It is located on the opening.

  That is, as shown in FIG. 2, the contact 13 between the first layer wiring and the low resistance layer in the drain region and the contact 14 between the first layer and the second layer wiring are formed on the same axis. The difference between this structure and the prior art will be described below with reference to FIGS. 45 and 46. FIG.

  FIG. 45 is a plan view showing a contact portion of a drain wiring according to the prior art. On the other hand, FIG. 46 is a plan view showing the contact portion of the drain wiring of the semiconductor device according to the first embodiment. The conventional technique referred to here employs a normal two-layer wiring technique attempted by the inventors.

  In the prior art shown in FIG. 45, the first layer wiring 11 (M1) is directly connected to the drain region as an electrode extraction electrode (wiring) through a contact portion (opening) 13 provided in the first interlayer insulating film. It was. Then, the connection of the second layer wiring 12 (M2) for backing to the first layer wiring 11 (M1) is performed through the contact portion 14 provided in the second interlayer insulating film so as not to overlap the contact portion 13. It was broken. When the contact part 14 is laid out on the contact part 13, a recess is formed in the first layer wiring 11 in the contact part 13. For this reason, when the contact portion 14 is formed by the photolithography technique, an etching residue exists in the contact portion 14. Contact between the first-layer wiring 11 and the second-layer wiring 12 is not reliably made, leading to an increase in contact resistance. For this reason, there exists a problem that the effect of backing wiring cannot fully be drawn out. Therefore, the contact portion 14 and the contact portion 13 have to be laid out in a shifted manner.

  On the other hand, in the first embodiment, the step is eliminated because wiring is performed after the contact portion for drawing out the electrode is filled with the conductor plug (metal plug). Therefore, as shown in FIG. 46, it is possible to make the contact portions 13 and 14 coaxial, and there are advantages such as improved layout flexibility, improved contact current capacity, and reduced contact and wiring resistance. That is, the wiring resistance for the N-type source (low resistance) region 10, the N-type drain (low resistance) region 9, and the P-type source punching region 3 can be reduced. As a result, since the on-resistance can be reduced, high added efficiency of the semiconductor device can be achieved.

  It is well known to employ metal plug technology for CMOS transistors and the like. For example, such a technique is disclosed in JP-A-6-350042. Although not clarified in the above publication, the metal plug technology is usually intended to prevent disconnection when forming an upper wiring pattern. In particular, in consideration of the case where the first layer wiring or the second layer wiring crosses the gate electrode (wiring), the metal plug technique is applied to the electrode lead-out.

  However, according to the first embodiment, the metal plug is applied in a situation where the gate electrode and the second layer wiring (M2) for drain do not cross each other. That is, the first embodiment is based on a completely different idea from the application of the conventionally known metal plug technology.

  FIG. 2 shows the case where there are two gate electrodes 3. However, in the case where there are four gate electrodes 3, a layout structure in which mirrors are inverted about the ZZ ′ axis as shown in FIG. Become. In consideration of the balance of drain current, an even number of gate electrodes 3 is provided so as to sandwich each drain electrode (drain region).

<Chip layout>
FIG. 3 shows the layout of the chip according to the first embodiment. The layout of the unit block portion shown in FIG. 3 has the configuration shown in FIG. 2 described above.

  The power MOSFET laid out in the chip shown in FIG. 3 has a plurality of unit blocks shown in FIG. 3 connected in parallel.

  That is, this embodiment mode includes a plurality of channel regions on a main surface of a semiconductor substrate having a semiconductor layer, a drain region and a source region provided across the channel regions, and gates on the surface of the channel regions. In an insulated gate semiconductor device having a gate electrode conductor layer provided via an insulating film, a metal plug is connected to the main surface of each of the drain region and the source region, and the metal plug The first metal conductor layer is connected to the first metal conductor layer, the interlayer insulating film is coated on the first metal conductor layer, and the drain provided on the interlayer insulating film is located on the metal plug connected to the drain region. Through the connection opening, the second metal conductor for drain with respect to the first metal conductor layer for drain among the first metal conductor layers. Are connected in common, and through the source connection opening provided in the interlayer insulating film, the second metal conductor for the source is connected to the first metal conductor layer for the source among the first metal conductor layers. The second metal for the gate is connected to the first metal conductor layer for the gate among the first metal conductor layers through the gate connection opening provided in the interlayer insulating film, the layers being commonly connected. Conductor layers are connected in common, the second metal conductor layer for drain has a bonding pad portion 22 for drain, and the second metal conductor layer for gate has insulating pad portion 23 for gate A gate-type field effect transistor is a unit block, and a plurality of insulated gate field-effect transistors of the unit block are arranged on the main surface of the semiconductor substrate, and between the unit blocks, The first metal conductor layer for serial gate and the second metal conductor layer for the gate is connected.

  As shown in FIG. 3, a plurality of drain pads 22 are arranged along one side of the chip, and a gate pad 23 and a source pad 20 are arranged along the other side of the chip. Of these, the source pad (probe source pad) 20 is not used for mounting but is mainly used only for element operation check. That is, the source pad 20 is provided to facilitate the operation check of the power MOSFET in a wafer state that is not divided into chips. The characteristics of each chip (MOSFET) can be inspected in a wafer state by bringing an inspection probe (prober) into contact with each of the pads 20, 22, and 23 provided on the upper surface of the substrate at the time of operation check.

  The gate pads arranged at both ends of the chip are provided with protective diodes 19 for preventing electrostatic breakdown of the gate insulating film. Hereinafter, the gate protection diode will be described.

<Gate protection diode>
4 and 5 show the configuration of the gate protection diode. FIG. 4 is a partially enlarged plan view of the gate protection diode 19 shown in FIG. FIG. 5 is a cross-sectional view taken along the line DD ′ in FIG.

  In FIG. 4 (FIG. 5), reference numeral 21 denotes a thick field oxide film. The gate pad 23 provided on the field oxide film 21 is integrally patterned with the second layer wiring 12 (M2). The gate pad 23 is connected to the P-type low resistance region 4 via the first layer wiring 11 (M1). A PNP structure diode (back-to-back diode) is formed by a P-type low resistance region 4b formed in a ring shape so as to surround the P-type low resistance region 4, the N-type high resistance region 8 and the P-type low resistance region 4a. ). The withstand voltage of this PNP structure is designed to be about ± 5 to 9 V, and the surge voltage on the gate pad can be clamped and absorbed. The P-type low resistance regions 4a and 4b are formed by the same process as the contact P-type low resistance region 4 shown in FIG.

  Further, a metal plug P1 is also adopted for this gate protection diode. The two striped metal plugs P1 are connected to the P-type region 8 (4) and function so that current flows uniformly.

<Process>
A method for manufacturing the silicon power MOSFET according to the first embodiment will be described below with reference to FIGS.

  6 to 9, FIG. 14, FIG. 20, FIG. 23, and FIG. 29, the cross-sectional view shown in (a) shows the XX ′ cut cross-section in FIG. The cross-sectional view shows a YY ′ cut cross-section in FIG. 2.

  (1) P-type through layer forming ion implantation step: As shown in FIGS. 6A and 6B, first, from a first conductivity type (specifically, P-type) Si A semiconductor wafer having a P-type semiconductor layer 2 formed on the main surface of the semiconductor substrate 1 is prepared. The P-type semiconductor layer 2 was formed by a known epitaxial growth method. Hereinafter, the P-type semiconductor layer 2 is referred to as a P-type epitaxial layer.

  As described above, the specific resistance of the semiconductor substrate 1 is 0.01 Ωcm. On the other hand, the specific resistance of the P-type epitaxial layer 2 is higher than the substrate specific resistance and has 20 Ωm. The thickness of the epitaxial layer 2 is set in a range of 2.5 to 3.5 μm in consideration of a reduction in on-resistance and a drain breakdown voltage. In this example, the thickness of the epitaxial layer 2 was set to 3 μm.

Subsequently, a silicon oxide (SiO ₂ ) film 100 having a thickness of 10 nm is formed on the surface of the epitaxial layer 2. Then, in order to form an ion implantation mask for forming a P-type punching layer, a photoresist pattern (mask) PR1 is formed on the SiO ₂ film 100 by using a photolithography technique.

  Subsequently, the surface of the silicon oxide film 100 and the epitaxial layer 2 is removed by etching using the mask PR1. The surface of the epitaxial layer 2 is etched to a depth of approximately 50 nm. Thereby, a step is formed on the surface of the epitaxial layer 2. This step can be used as a target for mask alignment.

Thereafter, in order to form the P-type punching layer 3, an impurity showing the first conductivity type (P-type) is introduced into the epitaxial layer 2 where the mask PR1 is not formed by ion implantation. That is, using the mask PR1, for example, boron (B +) of a P-type impurity is selectively ion-implanted into a deep position of the epitaxial layer 2 under the conditions of an acceleration energy of 80 KeV and a dose of 1.5 × 10 ¹⁶ / cm ^2. To do.

  (2) Field oxide film forming step: Mask PR1 and silicon oxide film 100 shown in FIG. 6 are removed. Thereafter, a field oxide film 21 for partitioning the unit block of the MOSFET is selectively formed by a LOCOS (Local Oxidation of Silicon) technique.

  First, as shown in FIGS. 7A and 7B, a silicon oxide film 100a is formed on the surface of the epitaxial layer as a pad oxide film by thermal oxidation. This pad oxide film avoids an insulating film (oxidation-resistant insulating film) made of a silicon nitride film to be a subsequently formed oxidation-resistant mask from directly contacting the silicon surface. When the silicon nitride film directly covers the silicon surface, thermal strain remains on the surface, causing crystal defects. That is, the pad oxide film is formed as a buffer film for preventing crystal defects.

  Subsequently, a silicon nitride film 101 is formed as an oxidation resistant mask. Then, the silicon nitride film 101 is patterned using a photolithography technique.

  Then, using the remaining silicon nitride film 101 as a mask, the surface of the epitaxial layer 2 where the silicon nitride film 101 is not formed is thermally oxidized to selectively form a field oxide film (LOCOS oxide film) 21 having a thickness of 350 nm. To do.

  What is important here is that the thermal oxidation (heat treatment) in this step is performed under the processing conditions of 1050 ° C. to 1100 ° C. for about 30 minutes, and is accompanied by stretching and diffusion of ion-implanted P-type impurities. Therefore, at this time, a P-type punching layer (P +) 3 reaching the semiconductor substrate 1 is formed in the epitaxial layer 2. That is, the heat treatment for forming the P-type punching layer 3 and the formation of the field oxide film 21 is not performed independently, but the heat treatment for forming them is performed at once. That is, the heat treatment (annealing) step for forming the P-type punching layer 3 can be omitted.

  Further, by omitting this heat treatment step, it is possible to suppress the boron impurity in the semiconductor substrate 1 from being auto-doping into the thin epitaxial layer 1. This suppression of impurity auto-doping can reduce the impurity concentration of the P well (PW) 5 described later, and can bring about the effect of reducing the on-resistance.

  The silicon nitride film 101 and the pad oxide film 100a are removed, and defects existing on the surface of the epitaxial layer 2 are removed. Subsequently, a silicon oxide film (100b) is formed on the surface of the epitaxial layer 2 by thermal oxidation.

  Then, the field oxide film 21 is annealed at a heat treatment temperature higher than the formation temperature of the silicon oxide film (100b) at about 1050 ° C. Annealing is aimed at reducing the crystal defects remaining on the surface of the active region where the MOSFET is formed and securing the breakdown voltage of the gate oxide film by reducing the thickness of the gate oxide film. Is an important means to obtain.

  (3) P-type well region forming first impurity introducing step: As shown in FIGS. 8A and 8B, a photoresist pattern (mask) PR2 is formed so as to cover the drain forming region.

Subsequently, an impurity having the first conductivity type is selectively introduced into the surface of the epitaxial layer 2 where the mask PR2 is not formed. For example, boron of a p-type impurity is selectively introduced into the epitaxial layer 2 with energy passing through the field oxide film 21 by ion implantation. That is, boron is introduced on the surface of the epitaxial layer 2 in contact with the field oxide film 21 so that the impurity concentration distribution after the annealing process has a substantially peak. As a result, a P-type high concentration region as a channel stopper is formed on the surface of the epitaxial layer 2. The ion implantation conditions are an acceleration energy of 200 KeV and a dose of 2.0 × 10 ¹³ / cm ² .

(4) P-type well region forming second impurity introducing step: Following the first impurity introducing step, as shown in FIGS. 9A and 9B, with the mask PR2 remaining, An impurity having the first conductivity type is selectively introduced into the epitaxial layer 2. For example, boron similar to that in the first impurity introduction step is selectively introduced into the epitaxial layer 2 by ion implantation. The ion implantation conditions are an acceleration energy of 50 KeV and a dose of 1.0 × 10 ¹³ / cm ² .

  As in the first and second impurity introduction steps, ion implantation is performed twice stepwise to make the well concentration distribution in the depth direction uniform and avoid heat treatment (high-temperature annealing) for stretching diffusion. can do. Note that the order of the first and second impurity introduction steps may be reversed.

(5) Ion implantation process for adjusting threshold voltage: Although not shown, after removing the mask PR2 shown in FIG. 9, impurities are introduced for adjusting the threshold voltage (Vth). For example, BF ₂ ions are implanted into the surface of the epitaxial layer 2 under the conditions of an acceleration energy of 50 KeV and a dose of 1.0 × 10 ¹² / cm ² . Subsequently, after the surface of the epitaxial layer 2 is cleaned, the impurity implanted in the steps (3) and (4) is extended and diffused by annealing (950 ° C., 60 seconds) to form a P-type well serving as a channel formation region of the MOSFET. Region (punch-through stopper layer) 5 is formed.

  (6) Gate insulating film forming step: The silicon oxide film 100b (FIG. 9) that has been subjected to ion implantation damage is removed, and the surface thereof is exposed. Then, a gate oxide film 6 having a thickness of 10 nm or more and 12 nm or less is formed on the exposed surface of the P-type well region 5 by thermal oxidation (see FIG. 10). According to the first embodiment, the thickness of the gate oxide film 6 is set to 11 ± 0.5 nm.

  As the gate insulating film 6, a silicon oxide film containing nitrogen, a so-called oxynitride film, may be applied instead of the thermal oxide film. In this case, hot electron traps at the interface of the gate insulating film can be reduced, and hot carrier countermeasures can be taken. That is, according to the oxynitride film, the trap at the film interface can be terminated by combining nitrogen (N).

Further, the gate insulating film 6, a SiO ₂ film by thermal oxidation (thickness: 4 nm): laminated and, SiO ₂ film (7 nm thick) by the thick CVD method than its SiO ₂ film on its SiO ₂ film A stacked gate insulating film may be applied. Specifically, a high temperature low pressure decomposition (HLD) film is used as the SiO ₂ film by the CVD method. The HLD film uses a TEOS (tetraethyl orthosilicate) material that is an organic source, has excellent film thickness uniformity, and is effective in preventing the diffusion of impurities into the film. The adoption of such a gate insulating film is particularly effective in the embodiment of a P-gate / N-channel Si power MOSFET described later. This is because in the case of a P-type gate electrode, the denseness of the gate oxide film is impaired due to leakage of boron (impurities) contained in the electrode. For this reason, the application of the stacked gate insulating film prevents boron leakage and prevents the breakdown voltage of the gate insulating film from deteriorating.

  (7) Step of forming gate electrode conductor layer: Subsequently, as shown in FIG. 10, a polycrystalline silicon layer (doped polysilicon) containing a phosphorus impurity having a thickness of about 100 nm is formed on the surface of the gate oxide film 6. silicon) 7a is coated by CVD. Subsequently, in order to obtain a low-resistance gate electrode, a metal silicide layer 7b, for example, a tungsten silicide (WSi) layer having a thickness of about 150 nm thicker than the polycrystalline silicon layer 7a is laminated on the surface of the polycrystalline silicon layer 7a. To do. On the surface of the WSi layer 7b, a silicon oxide film 20 having a thickness of 150 nm is formed as a protective film (cap layer) by thermal decomposition of organosilane. Providing such a cap layer is well known in the technical field of CMOS LSI, but has not been studied in the technical field of RF power MOS.

  (8) Gate electrode mask pattern forming step: As shown in FIG. 11, a photoresist pattern (mask) PR3 for forming a gate electrode is formed. The pattern width of the mask PR3 defines the gate length and is formed to be 0.35 μm or less.

  (9) Gate electrode pattern forming step: FIG. 12 shows a state after the gate electrode pattern is formed. Using the mask PR3 shown in FIG. 11, the cap layer 20, the tungsten silicide layer 7b, and the polycrystalline silicon layer 7a are sequentially etched to form the gate electrode 7 composed of the polycrystalline silicon layer 7a and the WSi layer 7b. To do.

(10) Drain offset region forming step: As shown in FIG. 13, the low-concentration semiconductor region 8 is self-aligned with the gate electrode 7 by ion implantation in the P-type well region 5. This low concentration semiconductor region (drain offset region) 8 is intended to improve the drain breakdown voltage. Ion implantation for forming the drain offset region 8 is performed using phosphorus, which is an N-type impurity, for example, under conditions of an acceleration energy of 50 KeV and a dose of 1.0 × 10 ¹³ / cm ² .

  According to the experiment, the relationship between the drain offset region (offset layer) and the on-resistance is as shown in FIG. Therefore, the depth of the offset layer is set to 0.2 μm or more.

(11) Source / drain region forming step: As shown in FIGS. 14A and 14B, a photoresist pattern (mask) PR4 is formed so as to cover a part of the drain offset region 8 and the P-type punching layer 3. . Subsequently, using the mask PR4, impurities are introduced for forming source / drain regions. Impurity is introduced by ion implantation, and arsenic, which is an N-type impurity, passes through the silicon oxide film (gate oxide film) 6 under the conditions of an acceleration energy of 60 KeV and a dose of 8.0 × 10 ¹⁵ / cm ^2. 8 is selectively introduced.

(12) Contact region forming step In order to reduce the resistance of the surface of the P-type punching layer 3, boron fluoride as a P-type impurity is formed on the surface of the P-type punching layer 3 using a mask PR5 as shown in FIG. (BF ₂ ) is introduced under the conditions of an acceleration energy of 40 KeV and a dose of 2.0 × 10 ¹⁵ / cm ² . Thereafter, an annealing process is performed. Thereby, the P-type contact region 4 is formed on the surface of the P-type punching layer 3.

(13) First Insulating Film (Interlayer Insulating Film) Formation Step A first insulating film 20 is formed on the entire surface of the semiconductor substrate 1 as an interlayer insulating film. First, as shown in FIG. 16, a CVDSiO ₂ film 20A (thickness: 100 nm) and a plasma TEOS film 20B (thickness: 800 nm) having excellent flatness are sequentially formed on the semiconductor substrate 1. Since the surface of the plasma TEOS film 20B has a step on the gate electrode, it is polished and flattened by about 100 nm using a chemical-mechanical polishing (CMP) technique.

  Until now, the use of CMP technology has been adopted in ICs (LSIs), but not in high-frequency power MOSFETs.

  In the first embodiment, by adopting this CMP technique, a metal plug described below can be realized, and a power MOSFET with reduced on-resistance can be obtained.

  Subsequently, as shown in FIG. 17, a PSG film 20C (thickness: 300 nm) is formed on the plasma TEOS film 20B. The total thickness of the first insulating film 20 is 1200 nm, which is thicker than two insulating films (interlayer insulating films) described later. This is to reduce the parasitic capacitance of the wiring.

The CVDSiO ₂ film 20A can be replaced with silicon nitride (SiN). The adoption of this silicon nitride blocks the penetration of hydroxide ions (OH ⁻ ) into the gate oxide film and is effective as a countermeasure against hot carriers.

  (14) Electrode Leading Opening Formation Step As shown in FIG. 18, a photoresist pattern (mask) PR6 is formed on the PSG film 20C. Subsequently, as shown in FIG. 19, the first insulating film (20) is selectively removed using a mask PR6 to form an electrode lead-out opening CH1.

  (15) Metal Plug Formation Step As shown in FIGS. 20A and 20B, metal plugs P1 made of W (tungsten) are formed in the electrode lead-out openings CH1, respectively.

  First, a TiN (titanium nitride) layer as a barrier layer is formed on the surface of the first insulating film (20) where the electrode lead-out opening CH1 is formed so that W (tungsten) does not diffuse into the semiconductor regions (8, 9). Is formed by sputtering. Subsequently, a refractory metal layer made of, for example, W (tungsten) is formed by a CVD method. Then, the refractory metal layer and the barrier layer are etched back. As a result, the metal plug P1 having substantially the same surface as the first insulating film 20 is buried in the electrode lead-out opening CH1. That is, the metal plug P <b> 1 is connected to the source region (first region) 10, the drain region (second region) 9, and the reach through layer 3.

  (16) First Conductor Layer (First Layer Wiring) Formation Step As shown in FIG. 21, a first conductor layer (first layer wiring) M1 is formed on the first insulating film 20 by sputtering. The first conductor layer is made of an aluminum alloy having low resistance and migration resistance. As a more specific material, an AlCu alloy is employed. Its film thickness is about 400 nm. Subsequently, as shown in FIG. 22, a photoresist pattern (mask) PR7 is formed on the first conductor layer M1. Then, as shown in FIGS. 23A and 23B, the first conductor layer M1 is patterned using the mask PR7.

  (17) Second Insulating Film (Interlayer Insulating Film) Formation Step A second insulating film 30 is formed on the entire surface of the semiconductor substrate 1 as an interlayer insulating film. As shown in FIG. 24, a plasma TEOS film 30A (thickness: 300 nm), an SOG film 30B (thickness: 300 nm), and a plasma TEOS film 30C (thickness: 300 nm) are sequentially formed on the semiconductor substrate 1. The SOG film 30B is formed to alleviate the level difference of the plasma TEOS film 30A.

  (18) Wiring Connection Opening Formation Step As shown in FIG. 25, a photoresist pattern (mask) PR8 is formed on the second insulating film 30. Subsequently, as shown in FIG. 26, by using the mask PR8, the second insulating film 30 (30A, 30B, 30C) is selectively removed to form a wiring connection opening CH2. FIG. 26 shows a cross-sectional structure of the semiconductor device after the mask PR8 is removed.

  (19) Step of Forming Second Conductor Layer (Second Layer Wiring) As shown in FIG. 27, the second conductor layer (second layer wiring) M2 is replaced with the first insulating film 30 by the same method as the first conductor layer M1. Form on top. Further, the same material as that of the first conductor layer is selected as the material of the second conductor layer (second layer wiring) M2. However, the film thickness is about four times that of the first conductor layer M1, so that the resistance of the backing wiring is reduced.

  Subsequently, as shown in FIG. 28, a photoresist pattern (mask) PR9 is formed on the first conductor layer M1.

  Then, as shown in FIG. 29, using the mask PR9, the second conductor layer M2 is patterned to form the drain electrode (drain wiring) D and the source electrode (source wiring) S (1). The source electrode (source wiring) S (1) electrically connects the first-layer source wiring (M1) between cells and between blocks. FIG. 29 shows the cross-sectional structure of the semiconductor device after the mask PR9 is removed.

  (20) Source Back Electrode Formation Step Although not shown in FIG. 29, after the step (19), a surface protective film is formed on the drain electrode (drain wiring) D and the source electrode (source wiring) S (1). Then, the surface protective film is selectively removed so as to expose the pad portion. Subsequently, the back surface (lower surface) of the semiconductor substrate 1 is ground to reduce its thickness. This grinding is performed as a pretreatment for converting a semiconductor wafer into a semiconductor chip. Then, a Ni layer (thickness: about 0.1 μm), a Ti layer (thickness: about 0.15 μm), a Ni layer (thickness: about 0.2 μm), and an Ag layer (thickness) having good solderability on the back surface. S: 1.3 μm) are sequentially laminated to form a source back electrode. The lower Ti layer is formed for adhesion between the Ni layer as a barrier layer and the Si substrate, and the upper Ti layer is formed for adhesion with the Ag layer.

  Note that when the Ag layer is attached (soldered) to the module substrate, attention must be paid to the Ag layer peeling due to oxidation. An Au layer may be used instead of the Ag layer. In this case, since the Au layer does not peel off during soldering, a low resistance contact with the module substrate can be achieved.

  According to this process, the following effects can be obtained.

  (a) The thermal oxidation (heat treatment) performed in the step (2) is accompanied by stretching and diffusion of ion-implanted P-type impurities.

  Therefore, at this time, a P-type punching layer (P +) 3 reaching the semiconductor substrate 1 is formed in the epitaxial layer 2. That is, the heat treatment for forming the P-type punching layer 3 and the formation of the field oxide film 102 is not performed separately, but the heat treatment for forming them is performed at once. For this reason, the heat treatment (annealing) step for forming the P-type punching layer 3 can be omitted.

  (b) For the above reason (a), autodoping of impurities from the substrate to the epitaxial layer can be suppressed. For this reason, the impurity concentration of the P well (PW) is easy to control and can be kept low. Therefore, a sufficient breakdown voltage can be ensured even if the gate length is shortened to reduce the on-resistance.

  Therefore, simplification of the heat treatment process contributes to reduction of on-resistance.

  (c) For the reasons (a) and (b) above, it is not necessary to increase the thickness of the epitaxial layer 2, and the thickness is set to 2.5 μm or more and 3.5 μm or less in consideration of the target breakdown voltage. It became possible. For this reason, the formation depth of the P-type punching layer (P +) 3 is also shallow, which contributes to a reduction in on-resistance.

  (d) Since the P well (PW) is formed after the field oxide film forming step, the P well is not affected by the heat treatment at the time of forming the field oxide film. That is, the P-well is not exposed to a high temperature of 1000 ° C. or higher. For this reason, the impurity concentration of the P well (PW) is easy to control and can be kept low. Therefore, a sufficient breakdown voltage can be ensured even if the gate length is shortened to reduce the on-resistance. Therefore, the order of the P well formation process as described above contributes to reduction of on-resistance.

  (e) As described in the above step (4), the P well formation step is performed by two-stage ion implantation. Therefore, a high temperature annealing process for stretching diffusion is unnecessary. That is, the annealing process in the step (5) can also be used. For this reason, the process can be simplified. In addition, it contributes to the reduction of on-resistance for the same reason as in (d) above.

  (f) As described in the step (2), after the field oxide film is formed, an annealing process is performed prior to the well region formation in the step (3), so that the active region in which the MOSFET is formed is Crystal defects remaining on the surface can be reduced, and the gate oxide film can be secured with a reduced thickness by reducing the thickness of the gate oxide film.

  (g) As described in the above step (10), the drain offset region (length) is defined by the mask PR4 and does not employ the LDD structure using the sidewall. That is, a high resistance region such as a drain offset region is not formed on the source region side. Thereby, the drain breakdown voltage can be improved and the on-resistance can be reduced.

<Conditions for MOSFET formation>
The conditions for forming the MOSFET in the first embodiment will be described below.

  The resistance component of the MOSFET chip in this embodiment will be described with reference to FIG.

  FIG. 30 is a resistance model of the MOSFET according to the first embodiment shown in FIG. 1, where RONO is the resistance of the entire chip, Ron is the resistance obtained by removing the P-type punched layer and the resistance of the substrate from RONO (the source is the surface of the substrate) R1 is the drain wiring resistance, Rr is the offset region resistance, Re is the channel resistance, R2 is the source wiring resistance, R3 is the source punching layer resistance, R4 is the resistance of the P-type substrate, and R5 is R3. Total resistance with R4.

  In describing the effect of the first embodiment, in order to separate the influence of the MOSFET main body and the substrate back surface electrode, the on-resistance is Ron instead of RONO, and Ron · Wg normalized by the gate width Wg is used. From the same point of view, the mutual conductance, threshold voltage, etc. are the performance of the FET with the source taken out from the substrate surface unless otherwise noted. The gate length, gate oxide film thickness, and offset layer of the first embodiment will be described.

  FIG. 31 shows the relationship between the gate oxide film thickness and the on-resistance in consideration of the gate breakdown voltage (oxide film allowable electric field). FIG. 32 shows the relationship between the gate length and on-resistance, and FIG. 33 shows the relationship between the gate length and mutual conductance. FIG. 34 shows the relationship between the gate length and the threshold voltage. FIG. 35 shows the relationship between the offset layer depth and the on-resistance. FIG. 36 shows the relationship between the offset length and the on-resistance, and FIG. 37 shows the offset length and the drain breakdown voltage.

  In FIG. 31, it is important that the gate oxide film is thin in order to obtain the required upper limit value of 4 Ωmm for the on-resistance. On the other hand, from the viewpoint of the reliability of the gate oxide film, the maximum value of the input amplitude in GSM application is A film thickness of 10 nm or more with no problem in reliability is required for 5V. As a result, considering the variation, the thickness of the gate oxide film is set to 10 nm or more and 12 nm or less. 32 and 33, the ON resistance is reduced and the mutual conductance is improved by shortening the gate length, and the ON resistance is 4 Ωmm or less and the mutual conductance is 150 mS / mm or more at the gate length of 0.35 μm. . That is, the channel direction length of the gate electrode is set to 0.35 μm or less.

  In addition, these results show the case where it measures from the source electrode on the surface. The prior art here refers to a high-frequency power MOSFET having a gate length of 0.4 μm, an offset length of 0.7 μm, and a gate oxide film thickness of 20 nm.

  With respect to the gate length, as shown in FIG. 34, the lowering of the threshold voltage becomes severe, and the gate length of about 0.3 μm is a typical specification value. Incidentally, in the MOSFET of this embodiment, the entire process is subjected to low temperature processing (heat treatment at 1200 ° C. or lower), so that the threshold voltage exhibits reverse short channel characteristics and the conventional structure has no reverse short channel characteristics. Compared with, Lowering is suppressed to a short gate length. As for the offset region (offset layer), as shown in FIG. 35, a depth of 0.2 μm or more with little resistance change is set, and from FIGS. 36 and 37, the offset length is 0.4 μm. The design value is 0.8 μm or less. The reason for selecting this length is that the drain breakdown voltage is determined on the drain low resistance layer side, the parasitic bipolar operation is unlikely to occur, and the on-resistance is sufficiently low. FIG. 38 shows the relationship between the punch-through stopper layer of the first embodiment (P-type well region 5 shown in FIG. 1) and on-resistance, and FIG. 39 shows the relationship between the drain breakdown voltage and the position of the punch-through stopper layer. Show. The position of the drain end of the gate electrode is the reference (zero), the distance to the drain side is plus (+), and the source side is minus (−). By shifting the punch-through stopper to the source side, the on-resistance decreases, but the breakdown voltage decreases on the minus side around zero. This is because punch-through occurs between the drain and the source. From this relationship, the position of the punch-through stopper is suitably 0 or more and 0.2 μm or less. Next, substrate formation conditions for the MOSFET of this embodiment will be described below.

  FIG. 40 shows the concentration distribution in the depth direction in the vicinity of the punched layer (BB ′ plane in FIG. 1) when the epitaxial layer thickness is changed, and FIG. 41 shows the resistivity of the punched layer when the epitaxial layer thickness is changed. Respectively. FIG. 42 shows the concentration distribution in the vicinity of the offset layer (CC ′ plane in FIG. 1), and FIG. 48 shows the epitaxial layer thickness and (drain) breakdown voltage.

  In FIGS. 40 and 41, when the thickness of the epitaxial layer is 4 μm, the epitaxial layer is not connected to the punched layer, and needs to be 3.5 μm or less.

  42 and 43, the breakdown voltage with respect to the drain N-type layer is a necessary and sufficient value when the thickness of the epitaxial layer is 2.5 μm or more. Therefore, the thickness of the high resistance layer (epitaxial layer) formed on the low resistance semiconductor substrate is suitably 2.5 μm or more and 3.5 μm or less. FIG. 44 shows a comparison of static characteristics between the present invention and a conventional MOSFET having a gate length of 0.4 μm. This is the case of both elements having a gate width of 36 mm, and on-resistance, mutual conductance, saturation current, etc. are greatly improved by the present invention.

  Next, FIG. 47 shows the large signal high frequency characteristics of the MOSFET chip according to the first embodiment (the present invention). FIG. 47 shows the relationship between the output power and the added efficiency when a 900 MHz sine wave signal is input with a power supply voltage of 3.5 V and a constant bias current on the premise of GSM application. The present invention is compared with the prior art. The former gate width is 28 mm, and the latter is 36 mm. In both cases, the output side is tuned so that the added efficiency peaks at an output power of 2.0 W. As can be seen from this figure, in the present invention, the peak efficiency is improved by about 5% compared to the prior art, and 65% is realized. Next, FIG. 48 shows the gate width dependence of the large signal high frequency characteristics of the chip of the present invention. The characteristics shown in FIG. 48 are measured in the same manner as the characteristics shown in FIG. 47 described above, but optimal tuning is performed to obtain efficiency for each gate width. FIG. 48 shows that the optimum gate width for obtaining an additional efficiency of 65% or more at 2 W is preferably about 28 mm. Even in the range of 24 mm to 32 mm, performance equivalent to this is obtained. Similarly, considering the application of PCS and evaluating the large signal characteristics at 1900 MHz, an additional efficiency of about 55% at a gate width of 12 mm and an output of 1 W was realized.

<Configuration of amplifier>
FIG. 49 shows a circuit configuration of an amplifier using the MOSFET of this embodiment. The amplifier shown in FIG. 4 is a three-stage amplifier circuit for GSM application, and one MOSFET (1 chip) is used for each of the input stage and the middle stage. Then, two MOSFETs (2 chips) are used in the output stage to constitute a parallel matching circuit (DD-CIMA: Divided and Collectively Impedance Matched Amplifier). The gate width (Wg) of the MOSFET is 6 mm for the input stage, 18 mm for the middle stage, and 28 mm for the output stage (2 chips). Input / output matching is performed for each element by the strip line 100 and the chip capacitor, and the output power is designed to be drawn efficiently. A bias voltage for operating point control is applied to the input of each stage by resistance division, and output power is controlled by controlling this voltage.

  The DD-CIMA was developed as a solution to the characteristic that the output voltage saturates when the gate width is increased, and two elements (chips) are arranged in parallel as an output stage of a module that requires high output in parallel matching. (Reference 2). With this circuit technology, an output power approximately twice the output power that can be output by one element can be obtained. Moreover, it is excellent in heat dissipation by dividing | segmenting a chip | tip.

  FIG. 50 shows a package module in which the present amplifier is incorporated in a package. Reference numeral 500 denotes a multilayer ceramic package having a multilayer wiring structure. A microstrip line 501 is formed on the surface of the package 500 by metal plating. In this module, an overall efficiency of about 55% at a saturation output power of 4 W and an output of 3.5 W is realized under the conditions of a frequency of 900 MHz, a power supply voltage of 3.5 V, and an input power of 0 dBm.

  In this embodiment, discrete products such as MOSFETs, capacitors, resistors, etc. are modularized, but the technology of the present invention can be applied to a circuit in which all or part of them are integrated. In addition, it is not always necessary to use devices having the same structure for each stage of the three-stage amplifier circuit. For example, since the first stage and middle stage elements require high gain, elements with short gate lengths or offset lengths may be used. is there.

(Embodiment 2)
Another embodiment of the present invention will be described with reference to FIGS.

<Cross-sectional structure of basic cell>
FIG. 51 is a cross-sectional view of the MOSFET according to the second embodiment having a structure in which the oxide film thickness at both ends of the gate electrode of the first embodiment is increased, that is, a gate bird's beak. FIG. 52 shows the voltage dependency of the gate-drain capacitance of the second embodiment. FIG. 53 shows the relationship between the small signal gain and the frequency.

  In FIG. 51, the oxide film thickness at both ends of the gate is a taper shape (or a bird's beak shape appearing by LOCOS selective oxidation) with a maximum film thickness of 30 nm with respect to the gate oxide film thickness of 10 nm.

  That is, the semiconductor device according to the second embodiment includes a first conductivity type semiconductor substrate and a first conductivity type semiconductor substrate having a lower impurity concentration than that of the semiconductor substrate, which is located on one main surface of the semiconductor substrate. A semiconductor layer, a first region and a second region of a second conductivity type opposite to the first conductivity type, spaced apart from each other in a main surface of the semiconductor layer; and a main surface of the semiconductor layer A third region having a lower impurity concentration than the first region, located between and in contact with the second region, between the first region and the second region, A gate insulating film on a main surface of the semiconductor layer located between the first region and the third region, and a part of which overlaps the first region and the third region, respectively. A gate electrode provided through the first region and the first region A first electrode and a second electrode connected to each of the second regions, and a third electrode connected to the other main surface opposite to the one main surface of the semiconductor substrate, The first film thickness (6a) of the gate insulating film existing while the three regions and the gate electrode overlap is on the main surface of the semiconductor layer located between the first region and the third region. Is larger than the second film thickness (6b) of the gate insulating film.

  As a result, as shown in FIG. 52, the gate-drain capacitance (Cdg) was reduced by about 20% under the conditions of 10 nm to 30 nm. The measuring method is as the circuit configuration shown in FIG. Reduction of the gate-drain capacitance (Cdg) can lead to a reduction in feedback capacitance (Crss) required for high gain RF operation.

  Further, as shown in FIG. 53, the small signal gain is also improved by about 0.5 dB around the frequency of 900 MHz.

According to the second embodiment, electric field relaxation can be achieved by providing bird's beaks. When the depth from the surface of the offset layer 8 is within 0.005 μm, the surface impurity concentration is set to a peak value of 1 × 10 ¹⁹ / cm ³ or more, and the on-resistance can be further reduced.

  In the second embodiment, the oxide film thickness on both the drain and source sides of the gate electrode is increased, but the object can be achieved by increasing the thickness only on the drain side. The embodiment will be described later.

<Process>
Following the step (9) of the first embodiment (see FIG. 12), the following steps are performed.

  (9-1) As shown in FIG. 54, the oxide film 21 is selectively formed by thermal oxidation. At this time, a bird's beak is formed at the end of the gate electrode. That is, an oxide film (maximum film thickness: 30 nm) thicker than the gate oxide film (thickness 10 nm) is formed below the end of the gate electrode.

  (9-2) Subsequently, as shown in FIG. 55, impurity introduction for forming the drain offset region is performed through the silicon oxide film 21. That is, the low-concentration semiconductor region (drain offset region) 8 is self-aligned with the gate electrode 7 by ion implantation in the P-type well region 5. Ion implantation for forming the drain offset region 8 uses phosphorus which is an N-type impurity.

  Subsequently, the process described in the first embodiment, from the (11) source / drain region forming step to the (20) source back electrode forming step, is performed.

  With the above method, the power MOSFET shown in FIG. 56 is completed.

(Embodiment 3)
Another embodiment of the present invention will be described with reference to FIGS.

<Cross-sectional structure of basic cell>
The third embodiment is a modification of the second embodiment, in which a part of the gate oxide film is thickened only on the drain side of the gate electrode (see FIG. 60).

<Process>
Following the step (9) of the first embodiment (see FIG. 12), the following steps are performed.

  (9-1) A silicon nitride film 200 is formed on the semiconductor substrate 1 as shown in FIG.

  (9-2) Subsequently, as shown in FIG. 58, the silicon nitride film 200 is selectively removed so that the end of the gate electrode on the drain side is exposed. Then, gate bird's beaks are formed only on the drain side by thermal oxidation using the silicon nitride film 200 as a mask.

  (9-3) Subsequently, as shown in FIG. 59, impurity introduction for forming the drain offset region is performed through the silicon oxide film 21. That is, the low-concentration semiconductor region (drain offset region) 8 is self-aligned with the gate electrode 7 by ion implantation in the P-type well region 5.

  Subsequently, the processes from step (11) to step (20) of the first embodiment are performed. The power MOSFET shown in FIG. 60 is completed by the above method.

(Embodiment 4)
A fourth embodiment of the present invention will be described with reference to FIG.

  The fourth embodiment provides an N-gate MOS in which the drain offset region 8 is formed only on the drain region 9 side.

  According to the fourth embodiment, as shown in FIG. 61, a deep N-type high resistance region like the drain offset region 8 is not provided on the source side (N-type source region 10 having a high impurity concentration). . Therefore, the amount of overlap between the gate electrode on the source side and the N-type region (source region 10) is smaller than that in the case where the drain offset region 8 exists on the source side as in the first embodiment, and the short channel characteristics. It is effective for improvement.

  In the process of the fourth embodiment, in accordance with the process of the first embodiment, in the step (10), ion implantation for forming the drain offset region 8 only on the drain side is performed using a mask. In this case, the photolithography process is increased once compared with the first embodiment.

(Embodiment 5)
A fifth embodiment of the present invention will be described with reference to FIGS.

FIG. 62 is a cross-sectional view when the concentration near the surface of the drain offset region is increased. This structure is effective for reducing the deterioration rate of on-resistance due to the influence of hot electrons injected into the oxide film on the offset region. After performing ion implantation for forming the offset region 8 shown in FIG. 1, As (arsenic) ions are implanted into the surface of the offset region 8 under the ion implantation conditions of about 20 KeV and 3 × 10 ¹³ atoms / cm ² . A second offset region 8a is formed. At this time, the surface concentration of the gate end is the most important. That is, FIG. 63 shows the relationship between the deterioration rate of on-resistance due to hot electrons and the gate end surface concentration of the offset layer. Without countermeasures, degradation of about 25% occurs, but with this structure, the degradation rate can be suppressed to 10% or less by setting the surface concentration to 1 × 10 ¹⁸ atoms / cm ³ . This is because the N-type offset layer is less susceptible to the influence of electrons injected into the oxide film by increasing the surface concentration.

  In the manufacturing method according to the fifth embodiment of the present invention, the ion implantation for forming the offset region 8 and the ions for forming the second offset region 8a are performed in the (10) drain offset region forming step in the first embodiment. Driving is done sequentially.

(Embodiment 6)
A sixth embodiment of the present invention will be described with reference to FIG. In FIG. 64, a P-type pocket layer 5a having an impurity concentration higher than that of the epitaxial layer 2 is provided at a position deeper than the offset region 8 in addition to the punch-through stopper 5 of the first embodiment. Under the N-type drain region 9, there is a P-type layer 201 formed simultaneously with the pocket layer 5a. The pocket layer 5a and the P-type layer 201 below the drain region 9 are formed, for example, by oblique implantation of B (boron) ions using a photoresist used when forming the N-type source / drain regions. The pocket layer 5a is effective for suppressing lowering of the threshold voltage. Further, the P-type layer 201 under the drain region 9 has an effect of separating the breakdown point of the MOSFET from the channel portion.

  Therefore, according to the sixth embodiment, it is possible to improve the short channel characteristics and the breakdown strength of the element.

(Embodiment 7)
Embodiment 7 of the present invention will be described with reference to FIGS. 65 and 66. FIG. 65 and 66 show a cross-sectional view and a block plan view of a power MOSFET in which a gate wiring (first layer wiring) is arranged in parallel with the gate electrode, respectively. 65 is a cross-sectional view taken along line EE ′ shown in FIG. According to the first embodiment described above, the first layer wiring 11 (M1) connected to the gate electrode is arranged so as to extend to the periphery of the unit block perpendicular to the gate electrode. According to the seventh embodiment, the gate wiring (first layer wiring) is arranged in parallel with the gate electrode, and is lined with the gate electrode.

  In FIG. 65, reference numeral 300 denotes a first layer wiring for gate shunt provided for reducing gate wiring resistance. The feature of the sixth embodiment is that since the drain first layer wiring and the gate wiring face each other, the parasitic wiring capacitance between the drain and the gate is increased, but the number of gate wirings is the same as the number of gate electrodes, Since the number of gate wirings is larger than that in the first embodiment, it is effective in reducing gate wiring resistance. This is applied when the gate resistance is more effective than the drain-gate capacitance.

(Embodiment 8)
An eighth embodiment of the present invention will be described with reference to FIG.

  A plan view (electrode pattern layout) shown in FIG. 67 is a modification of the first embodiment shown in FIG. According to the eighth embodiment, one second-layer wiring for the gate is taken from the center of the unit block. Thereby, as shown in FIG. 2, the distance from the gate pad to each MOSFET cell becomes equal as compared with the case where the second layer wiring for the gate is arranged on both sides of the peripheral portion of the unit block. Therefore, the operation timing shift due to the phase shift of the gate input signal of each FET cell is reduced, and the power loss in the entire chip can be reduced.

(Embodiment 9)
FIG. 68 shows a layout in which short gate electrodes are arranged without performing gate shunting by metal wiring (first layer wiring). In this case, the parasitic wiring capacitance between the drain and the gate can be reduced.

(Embodiment 10)
A tenth embodiment of the present invention will be described with reference to FIGS. 69 and 70. FIG.

  69 and 70 are modifications of the seventh embodiment, and show a cross-sectional view and a plan view of a power MOSFET provided with a source field plate 400, respectively. 70 is a cross-sectional view taken along line F-F ′ shown in FIG. 69.

  According to the tenth embodiment, as shown in FIG. 69, a part of the source first layer wiring extends on the offset region 8 to form the source field plate 400. That is, as shown in FIG. 70, the gate wiring (first layer wiring) is arranged in parallel with the gate electrode and backed by the gate electrode, as in the seventh embodiment. In the source field plate 400, the source first layer wiring 11 is inserted in a stripe shape along the gate electrode 7 between the drain wiring and the gate shunt wiring. This field plate 400 is fixed to the ground potential, and has an effect of improving the drain breakdown voltage by relaxing the electric field in the offset region 8.

(Embodiment 11)
An eleventh embodiment of the present invention will be described with reference to FIGS. 71 and 72. FIG.

  FIG. 71 is a plan view of a gate protection diode according to the eleventh embodiment. 72 is a cross-sectional view taken along line GG ′ in FIG.

  The gate protection diode of the first embodiment (see FIGS. 4 and 5) is connected to the gate pad by the second layer wiring. On the other hand, in the eleventh embodiment, as shown in FIG. 72, the gate pad and the gate electrode are already connected in the first layer wiring.

  As a result, it is possible to prevent the gate oxide film from being destroyed due to process damage such as charge-up in the process after the first layer wiring.

(Embodiment 12)
A twelfth embodiment of the present invention will be described with reference to FIG.

  FIG. 73 shows a layout of two elements of the MOSFET of the present invention used in the output stage of the amplifier circuit shown in FIG. 49 in one chip. Both gates and drains are connected by a resistance R of about 10Ω. For this resistance, for example, a gate electrode material is used.

  According to the twelfth embodiment, it is possible to reduce the performance variation of the two elements and the chip occupation area in the module.

(Embodiment 13)
A thirteenth embodiment of the present invention will be described with reference to FIG.

  FIG. 74 shows a layout of power MOSFETs used in the input stage and middle stage of the amplifier circuit shown in FIG. 49 in one chip. Since it is a common source circuit, the semiconductor substrate 1 is common, but the gate and drain of both are electrically insulated. In this case, as the shielding means, for example, a structure in which a P-type low resistance (reach through) layer is provided between them and a wiring layer is provided on the substrate surface is employed. Such a structure does not require a special process for forming the shield means, and can be obtained in the process of forming the power MOSFET of the first embodiment. Also according to the thirteenth embodiment, the chip occupation area in the module can be reduced. In the thirteenth embodiment, the two MOSFETs are laid out in an upside down relationship in order to increase the area efficiency of the module layout.

  Further, in an amplifier that handles two different frequencies, a so-called dual band amplifier, two sets of multistage amplifier circuits are incorporated in one module. For this reason, two sets of chips shown in FIG. 74 are also arranged. In this case, by using the first stage FET of one chip and the middle stage FET of the other chip to configure each amplifier circuit, adjacent FETs do not operate simultaneously, so that stable operation is achieved. It becomes possible.

(Embodiment 14)
A fourteenth embodiment of the present invention will be described with reference to FIG.

  FIG. 75 is obtained by adding a current detection MOSFET Ms to the chip of the twelfth embodiment shown in FIG. The cell structure of the MOSFET is the same as that of the output stage element, and its gate width is set to about 1/1000 of the output stage element. As a result, the current flowing through the output stage element is monitored and fed back to the control circuit. In addition to current detection, a MOSFET may be added as a switch element. This is used for applications such as dual band, where it is desired to completely turn off the element. Since such a MOSFET has a structure in which the gate and drain terminals are exposed, a protection element connected to each terminal is incorporated. Since Ms has a small gate width, when a positive high voltage is applied to the drain terminal in time, its energy cannot be absorbed by the breakdown current, leading to destruction. Also, in the case of a negative voltage, the body diode is turned on and a current flows, but the current capacity is insufficient and is destroyed. As a countermeasure for both, a diode having a breakdown voltage equivalent to that of a FET and having a sufficient size is used as a protective element.

(Embodiment 15)
A semiconductor device (P-gate / N-channel Si power MOSFET: P-gate MOS) according to the fifteenth embodiment of the present invention will be described with reference to FIGS. 76 to 78 and FIG. In the fifteenth embodiment, features are directed to the gate electrode and the bulk structure in order to reduce the on-resistance.

<Cross-sectional structure of basic cell>
FIG. 76 is a cross-sectional view of a basic cell formed of a P-gate MOS according to the fifteenth embodiment of the present invention.

  The P-gate MOS shown in FIG. 76 includes a P-type silicon semiconductor substrate 1, a P-type silicon semiconductor (epitaxial) layer 2 having a lower impurity concentration than that of the substrate, which is located on one main surface of the substrate, First N-type region (source region) 10 and second N-type region (drain region) 9 provided in the main surface of the epitaxial layer and spaced from each other, and source region 10 in the main surface of the epitaxial layer And a third N-type region (offset region) 8 having a lower impurity concentration than that of the drain region 9, which is located between and in contact with the drain region between the drain region 9 and the drain region 9; It is located between the source region 10 and the offset region 8 and is on the main surface of the region where the channel is formed, and the end portion overlaps the source region 10 and the offset region 8 respectively. And electrically connected to the P-type gate electrode 7 provided through the gate insulating film 6 and the source region 10 and the drain region 9 so as to terminate on the source region 10 and the offset region 8, respectively. A first electrode S (1) and a second electrode D, and a third electrode S (2) connected to the other main surface opposite to one main surface of the semiconductor substrate 1, and a source The impurity concentration distribution in the region (P-type well region) 5 where the channel located between the region 10 and the offset region 8 is formed includes an N-type distribution region 55 that decreases from the surface toward the semiconductor substrate 1. Yes. FIG. 82 shows an impurity distribution in the P-type well region 5 (G-G ′ cut portion) shown in FIG. 76.

  According to the fifteenth embodiment, since the gate electrode is a P-type semiconductor, that is, a P-gate, the threshold voltage Vth is 1 V due to the work function difference as compared with the N-gate (the gate electrode is an N-type semiconductor). Will go up. For this reason, it is possible to maintain a normally-off state, that is, an enhancement state in a state where no gate voltage is applied even though the N-type layer 55 is provided on the surface of the P-type semiconductor region. As shown in FIG. 77, the presence of the N-type layer 55 has the effect of extending the extension of the depletion layer 400 from the drain junction (Jd). The N-type layer 55 is not affected by the gate oxide film interface. For this reason, the drain breakdown voltage is improved. Therefore, when designing a P gate MOS having the same drain breakdown voltage as the N gate MOS, the concentration of the drain offset region can be increased. That is, it is not necessary to extend the depletion layer to the drain offset region side. The fact that the concentration of the offset region can be increased can reduce the resistance of the drain offset region as compared with the N-gate MOS. For this reason, it contributes to ON resistance reduction.

<Unit block layout>
The unit block layout of the fifteenth embodiment is as shown in FIG. 2 as in the first embodiment. Therefore, the description is omitted.

<Chip layout>
The chip layout of the fifteenth embodiment is as shown in FIG. 3 as in the first embodiment. Therefore, the description is omitted.

<Gate protection diode>
The gate protection diode of the fifteenth embodiment is as shown in FIGS. 4 and 5 as in the first embodiment. Therefore, the description is also omitted.

<Process>
A method for manufacturing the P-gate MOS according to the fifteenth embodiment will be described below with reference to FIGS. 78 (a) and 78 (b).

Subsequent to step (3) of the first embodiment, as shown in FIGS. 78 (a) and 78 (b), arsenic (As), which has a lower diffusion rate than phosphorus (P), is ionized using a mask PR2. It is selectively introduced into the epitaxial layer 2 by an implantation method. The ion implantation conditions are an acceleration energy of 80 KeV and a dose of 4.5 × 10 ¹¹ / cm ² . Subsequently, annealing treatment (950 ° C., 60 seconds) is performed to form an N-type region (N-type region 55 shown in FIG. 76) having a peak impurity concentration (about 6 × 10 ¹⁶ / cm ³ ) on the surface. To do. As described above, by using arsenic (As) as an impurity for forming the N-type region 55, the impurity is difficult to diffuse into the epitaxial layer, and the surface of the N-type region 55 can be maintained at a high concentration.

  Subsequently, after forming the gate oxide film in the step (6) of the first embodiment, the gate electrode conductor layer in the step (7) is formed (see FIG. 10). First, an intrinsic polycrystalline silicon layer 7a is coated by a CVD method. Then, boron impurities are introduced into the polycrystalline silicon layer 7a by ion implantation to form a P gate electrode. P gate electrode formation by ion implantation is employed for the purpose of suppressing the boron concentration in the vicinity of the gate oxide film in order to reduce damage to the gate oxide film by boron.

  Thereafter, steps from step (8) to step (20) of the first embodiment are performed.

(Embodiment 16)
The sixteenth embodiment provides a P-gate MOS in which the shallow offset region 8 is formed only on the drain region 9 side, and will be described below with reference to FIGS. 79 to 81.

  The sixteenth embodiment is based on the process of the fifteenth embodiment, and uses a mask PR10 during the drain offset region forming step (see the process of the first embodiment, step (10)) to form a P-type well region. 5 and P type source punching region 3 so that phosphorus is not introduced into the surface, and offset region 8 is formed only on the drain region 9 side.

  Subsequently, as shown in FIG. 80, source / drain regions (10, 9) are formed. The method for forming the source / drain regions (10, 9) follows the process and step (11) of the first embodiment. Thereafter, the process proceeds to the process and step (12) of the first embodiment.

  Thus, the P gate MOS is completed as shown in FIG.

  According to the sixteenth embodiment, phosphorus is not introduced into the surface of the P-type source punching region 3 by PR10. For this reason, the introduction of impurities for forming the P-type contact region on the surface of the P-type source punching region 3 does not require high-concentration ion implantation. That is, ion damage due to high concentration ion implantation can be avoided and the surface concentration of the P-type contact region can be increased. Therefore, a low resistance contact can be realized, which contributes to a reduction in on-resistance.

  The sixteenth embodiment can also be applied to the N-gate MOS as in the first embodiment.

(Embodiment 17)
The seventeenth embodiment is a modification of the fourteenth embodiment, and has a buried N-type layer in FIG. 76 where the peak position of the impurity distribution of the N-type layer 55 is set deeper than the epitaxial layer surface. The depth of the peak position of the buried N-type layer is approximately 0.05 μm from the surface, and the peak concentration is approximately 2 × 10 ¹⁷ / cm ³ .

  The manufacturing method of the seventeenth embodiment is performed based on the fifteenth embodiment. That is, the buried N-type layer is formed by setting the ion implantation conditions that make the impurity distribution in the N-type layer 55 forming step of the fifteenth embodiment.

  In the P-gate MOS having the buried N-type layer as in the seventeenth embodiment, since the N-type layer is buried, it is possible to avoid surface scattering of electrons due to the uneven interface of the gate oxide film. That is, in the sixteenth embodiment, only bulk scattering needs to be considered. Accordingly, carrier mobility is improved. In other words, the on-resistance can be reduced. The seventeenth embodiment can also be applied to the N-gate MOS as in the first embodiment.

  Although the invention made by the present inventor has been specifically described based on the above embodiment, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Of course.

  Based on the above embodiment, the characteristics of the present invention are summarized as follows.

  (1) A semiconductor device according to the present invention includes a first conductivity type semiconductor substrate, a first conductivity type semiconductor layer formed on an upper surface of the semiconductor substrate, and a channel formed on a part of a main surface of the semiconductor layer. The first and second regions of the second conductivity type opposite to the first conductivity type, which are spaced apart from each other with the region to be formed therebetween, and the second region are low in contact with the region where the channel is formed. A gate electrode comprising a concentration region and a high concentration region in contact with the low concentration region, and formed on the channel region via a gate insulating film; and a first region and the semiconductor substrate on the other main surface of the semiconductor layer A first conductivity type reach-through layer formed in contact with the gate electrode, a first insulating film covering the gate electrode, the first region, the second region, and the reach-through layer; and in the first insulating film Through the opening provided in the first region A first conductor plug, a second conductor plug and a third conductor plug connected to the high concentration region of the second region and the reach through layer, respectively, and a first conductor plug connected to the first conductor plug and the third plug. 1 conductor layer, the 2nd conductor layer connected to the said 2nd conductor plug, and the 3rd conductor layer connected to the lower surface of the said semiconductor substrate.

  (2) In the above (1), a second insulating film is coated on the first conductor layer and the second conductor layer, and the first conductor plug and the second conductor plug are covered with respect to the second insulating film. The first opening and the second opening are respectively provided in the second insulating film, the first wiring layer is connected to the first conductor layer through the first opening, and the second opening is provided through the second opening. A wiring layer is connected to the second conductor layer.

  (3) In the above (1), a third conductor plug is connected to the gate electrode through an opening provided in the first insulating film, and a fourth conductor layer is connected to the third plug.

  (4) In the above (1), the first and second conductor plugs are made of tungsten, and the first and second conductor layers are made of an aluminum alloy.

  (5) In the above (4), the first and second conductor layers are made of an AlCu alloy.

  (6) In the above (3), the third conductor plug is made of tungsten, and the fourth conductor layer is made of an aluminum alloy.

  (7) In the above (6), the first and second conductor layers are made of an AlCu alloy.

  (8) In the above (2), the first and second wiring layers are made of an aluminum alloy.

  (9) In (1), the first and second conductor plugs are made of W, the first and second conductor layers are made of an AlCu alloy, and the third conductor layer is in contact with the lower surface of the semiconductor substrate. The electrode structure contains Ni, Ti and Au.

  (10) In the above (3), the third conductor plug is made of W, the gate electrode has an electrode structure in which a metal silicide is laminated on polycrystalline Si, and the fourth conductor layer is made of an AlCu alloy.

  (11) A semiconductor device according to the present invention includes an insulated gate field effect transistor, a semiconductor body including a first conductivity type semiconductor substrate and a first conductivity type semiconductor layer formed on an upper surface of the semiconductor substrate, A protection diode connected to a gate to protect the transistor, and the insulated gate field effect transistor includes a region where a channel is formed in a first main surface portion of the semiconductor layer partitioned by an element isolation region. The first and second regions of the second conductivity type opposite to the first conductivity type, which are spaced apart from each other, the second region is a low concentration region in contact with the region where the channel is formed, and the low concentration region A gate electrode formed on the channel region via a gate insulating film, and the first region and the semiconductor on part of the first main surface portion. A first reach-through layer of a first conductivity type formed in contact with the plate; a first insulating film covering the gate electrode, the first region, the second region, and the first reach-through layer; A first conductor plug, a second conductor plug, and a second conductor plug connected to the first region, the high concentration region of the second region, and the first reach-through layer, respectively, through openings provided in the first insulating film. A three-conductor plug, a first conductor layer connected to the first conductor plug and the third plug, a second conductor layer connected to the second conductor plug, and a lower surface of the semiconductor substrate The protection diode is formed in the second region of the second conductivity type formed in the second main surface portion of the semiconductor layer partitioned by the element isolation region, and in the third region. The fourth region of the first conductivity type and the Consists of a region, which is the fourth region, the third region and the back-to-back diode is constituted by the above-described fifth region.

  (12) In the above (11), the fourth region is electrically connected to a gate electrode pad provided on the main surface of the semiconductor layer through a fourth conductor plug.

  (13) In the above (12), the fourth plug includes a plurality of plugs.

  (14) In the above (11), the second main surface portion is covered with the first insulating film, and the fourth conductor plug and the fifth conductor plug are respectively provided through the openings provided in the first insulating film. 4 regions and the fifth region, the sixth conductor layer and the seventh conductor layer are connected to the fourth conductor plug and the fifth conductor plug, the second main surface portion is in contact with the fifth region, and A second reach through layer in contact with the semiconductor substrate is disposed.

  (15) In (14), the sixth conductor layer extends on the element isolation region, and a gate electrode pad is connected to the sixth conductor layer on the element isolation region.

  (16) In the above (14), the first, second, third, fourth and fifth conductor plugs are made of tungsten, and the first, second, sixth and seventh conductor layers are made of an aluminum alloy. .

  (17) In the above (16), the first, second, sixth and seventh conductor layers are made of an AlCu alloy.

  (18) In a power insulated gate field effect semiconductor device having a drain offset region according to the present invention, an N-type drain region having an N-type source region and an offset region is formed apart from each other in a P-type silicon semiconductor layer, A gate electrode is formed on the surface of the P-type silicon semiconductor layer serving as a channel region between the N-type source region and the offset region via a gate insulating film, and the gate electrode is formed from a silicon semiconductor layer containing a P-type impurity. Become.

  (19) In the above (18), the gate electrode comprises a polycrystalline silicon layer containing a P-type impurity and a metal silicide layer formed on the polycrystalline silicon layer.

  (20) In the above (18), the gate insulating film is composed of a first silicon oxide film formed by thermal oxidation and a second silicon oxide film formed on the silicon oxide film by vapor phase chemical growth.

  (21) A semiconductor device according to the present invention includes a P-type silicon semiconductor substrate, a P-type silicon semiconductor layer having a lower impurity concentration than the substrate, which is located on one main surface of the substrate, and the semiconductor layer A first N-type region and a second N-type region which are provided apart from each other in the main surface; and the first N-type region and the second N-type region in the main surface of the semiconductor layer. A third N-type having a lower impurity concentration than that of the second N-type region, which is located between and spaced from the first N-type region and in contact with the second N-type region On the main surface of the semiconductor layer, which is located between the region, the first N-type region, and the third N-type region, and in which a channel is formed, and an end portion of the first region and the first region Overlapping each of the third regions and terminating on the first region and the third region, respectively As described above, the gate electrode provided through the gate insulating film, the first electrode and the second electrode connected to each of the first region and the second region, and one main surface of the semiconductor substrate And an impurity concentration distribution in the semiconductor layer located between the first N-type region and the third N-type region. And an N-type distribution region that decreases from the surface of the semiconductor layer toward the semiconductor substrate.

  (22) A semiconductor device according to the present invention includes a P-type silicon semiconductor substrate, a P-type silicon semiconductor layer having a lower impurity concentration than the substrate, which is located on one main surface of the substrate, and the semiconductor layer A first N-type region and a second N-type region which are provided apart from each other in the main surface; and the first N-type region and the second N-type region in the main surface of the semiconductor layer. A third N-type having a lower impurity concentration than that of the second N-type region, which is located between and spaced from the first N-type region and in contact with the second N-type region On the main surface of the semiconductor layer, which is located between the region, the first N-type region, and the third N-type region, and in which a channel is formed, and an end portion of the first region and the first region Overlapping each of the third regions and terminating on the first region and the third region, respectively As described above, the gate electrode provided through the gate insulating film, the first electrode and the second electrode connected to each of the first region and the second region, and one main surface of the semiconductor substrate And an impurity concentration distribution in the semiconductor layer located between the first N-type region and the third N-type region. A P-type distribution region that increases from the surface of the semiconductor layer toward the semiconductor substrate, and an N-type distribution region that overlaps the P-type distribution region and has an impurity concentration peak inside the semiconductor layer and away from the surface. Have

  (23) A semiconductor device according to the present invention includes a first conductivity type semiconductor substrate and a first conductivity type semiconductor layer located on one main surface of the semiconductor substrate and having a lower impurity concentration than the semiconductor substrate. A first region and a second region of the second conductivity type opposite to the first conductivity type provided in the main surface of the semiconductor layer and spaced apart from each other, and the above-mentioned in the main surface of the semiconductor layer A third region between the first region and the second region, spaced apart from the first region and located in contact with the second region, having a lower impurity concentration than the first region; and On the main surface of the semiconductor layer located between the first region and the third region, with a gate insulating film interposed between the first region and the third region so as to partially overlap the first region and the third region, respectively. Gate electrode, the first region and the second region A first electrode and a second electrode connected to each other; and a third electrode connected to the other main surface opposite to the one main surface of the semiconductor substrate, the first region and the first electrode A fourth region of the first conductivity type that terminates in the third region is selectively formed on the main surface of the semiconductor layer located between the third region and the fourth region located under the gate electrode. Within the region, a pocket layer of the first conductivity type having an impurity concentration higher than the surface impurity concentration of the fourth region is provided at a position deeper than the third region.

  (24) In the above (23), the first electrode and the third electrode are electrically connected.

  (25) The semiconductor device according to (23), wherein the first semiconductor layer is provided with the first region and a fifth region of a first conductivity type in contact with the semiconductor substrate.

  (26) In the above (23), the third electrode is connected to a first reference potential, and the second electrode is connected to a second reference potential.

  (27) In the above (26), the third electrode is a source electrode, and the second electrode is a drain electrode.

  (28) In the above (26) or (27), the first reference potential is a ground potential, and the second reference potential is a power supply potential.

  (29) In the above (23), the pocket layer is formed by an ion implantation method in an oblique direction with respect to the main surface of the semiconductor layer.

  (30) A semiconductor device according to the present invention includes a first conductivity type semiconductor substrate and a first conductivity type semiconductor layer located on one main surface of the semiconductor substrate and having a lower impurity concentration than the semiconductor substrate. A first region and a second region of the second conductivity type opposite to the first conductivity type provided in the main surface of the semiconductor layer and spaced apart from each other, and the above-mentioned in the main surface of the semiconductor layer A third region between the first region and the second region, spaced apart from the first region and located in contact with the second region, having a lower impurity concentration than the first region; and A gate insulating film is interposed on the main surface of the semiconductor layer located between the first region and the third region so as to partially overlap the first region and the third region. Gate electrode, and the first region and the second region. A first electrode and a second electrode connected to each of the semiconductor substrate, and a third electrode connected to the other main surface opposite to the one main surface of the semiconductor substrate, the third region and the gate The second film thickness of the gate insulating film on the main surface of the semiconductor layer located between the first region and the third region is the first film thickness of the gate insulating film existing while overlapping with the electrode. Greater than film thickness.

  (31) In the above (30), on the main surface of the semiconductor layer located between the first region and the third region, there is a fourth region of the first conductivity type that terminates in the third region. Selectively formed.

  (32) In the above (30) or (31), the first electrode and the third electrode are electrically connected.

  (33) In the above (30), the first semiconductor layer is provided with the first region and the fifth region of the first conductivity type in contact with the semiconductor substrate.

  (34) In (30), the third electrode is connected to a first reference potential, and the second electrode is connected to a second reference potential.

  (35) In the above (34), the third electrode is a source electrode, and the second electrode is a drain electrode.

  (36) In the above (34) or (35), the first reference potential is a ground potential, and the second reference potential is a power supply potential.

  (37) In the above (30), the gate insulating film having the first film thickness is formed to be thicker than the gate insulating film having the second film thickness.

  (38) In the above (37), the gate insulating film having the first film thickness has a bird's beak structure.

  (39) A semiconductor device according to the present invention includes: (a) a semiconductor substrate of a first conductivity type; and (b) a first impurity surface located on one main surface of the semiconductor substrate and having a lower impurity concentration than the semiconductor substrate. A semiconductor layer of one conductivity type; and (c) a first region and a second region of a second conductivity type opposite to the first conductivity type provided in the main surface of the semiconductor layer and spaced apart from each other; (d) From the first region between the first region and the second region in the main surface of the semiconductor layer, spaced from the first region and positioned in contact with the second region A third region having a low impurity concentration; and (e) a main surface of the semiconductor layer located between the first region and the third region, wherein a part of the third region and the first region A gate electrode provided through a gate insulating film so as to overlap each of the three regions, and (f) the first region and A first electrode and a second electrode connected to each of the second regions; and (g) a third electrode connected to the other main surface opposite to the one main surface of the semiconductor substrate. A bird's beak exists while the third region and the gate electrode overlap, and the impurity concentration on the surface of the third region is substantially equal to or higher than the impurity concentration of the second region.

(40) In the above (39), the impurity concentration on the surface of the third region has a peak value of 1E18 (1 × 10 ¹⁸ / cm ³ ) or more.

  (41) In the above (39) or (40), the impurity concentration on the surface of the third region is distributed within a depth of 0.005 μm from the surface.

  (42) A semiconductor device according to the present invention is provided with a substrate on which a first conductivity type semiconductor layer having a low impurity concentration is formed on a main surface and the main surface of the semiconductor layer spaced apart from each other. Between the first region and the second region of the second conductivity type opposite to the first conductivity type, and the first region and the second region in the main surface of the semiconductor layer, and separated from the first region And a main region of the semiconductor layer located between the first region and the third region, which is located in contact with the second region and has a lower impurity concentration than the first region. A gate electrode provided through a gate insulating film so as to partially overlap the first region and the third region, and the semiconductor layer under the gate insulating film A well region of a first conductivity type formed therein, and the third region The gate insulating film on the main surface of the semiconductor layer located between the first region and the third region has a first film thickness of the gate insulating film existing while the region and the gate electrode overlap. The third region is formed of a shallow high concentration region and a deep low concentration region.

  (43) In the above (42), the well region terminates in the third region.

  (44) In the above (42), the well region terminates under the gate electrode.

  (45) In the above (42), the gate electrode includes a polycrystalline silicon layer containing a P-type impurity and a refractory silicide layer laminated on the polycrystalline silicon.

  (46) A semiconductor device according to the present invention includes a semiconductor substrate, a semiconductor layer having a first conductivity type formed on a main surface of the semiconductor substrate, and the semiconductor layer main surface spaced apart from each other, First and second regions having a second conductivity type opposite to the first conductivity type, and in the main surface of the semiconductor layer located between the first region and the second region, the first region And a third region of a second conductivity type formed so as to be in contact with the second region, and a main surface of the semiconductor layer serving as a channel region between the first region and the third region. A gate oxide film formed thereon, a gate conductor layer provided on the gate oxide film, a first conductor layer connected to the first region, a second conductor layer connected to the second region, and And a third conductor layer connected to the back surface of the semiconductor substrate, and the first region and the top The thickness of each of the first gate oxide film positioned between the gate insulating film and the second gate oxide film positioned between the third region and the gate insulating film is a main layer of the semiconductor layer serving as the channel region. It is larger than the film thickness of the third gate oxide film provided on the surface.

  (47) In the above (46), a fourth region of the first conductivity type terminates in the third region on the main surface of the semiconductor layer located between the first region and the third region. ing.

  (48) In the above (46) or (47), the first conductor layer and the conductor layer are electrically connected.

  (49) In (46), the first semiconductor layer is provided with the first region and a fifth region of the first conductivity type in contact with the semiconductor substrate.

  (50) In (46), the third conductor layer is connected to a first reference potential, and the second conductor layer is connected to a second reference potential.

  (51) In the above (50), the third conductor layer is a source back electrode, and the second conductor layer is a drain electrode.

  (52) In the above (50) or (51), the first reference potential is a ground potential, and the second reference potential is a power supply potential.

  (53) In the above (46), the first and second gate oxide films have a bird's beak structure.

  (54) A plurality of channel regions on the main surface of the semiconductor layer, a drain region and a source region provided across each of the channel regions, and a gate provided on the surface of each channel region via a gate insulating film An insulated gate semiconductor device having a conductor layer for an electrode, wherein a metal plug is connected to a main surface of each of the drain regions and the source regions, and a first metal conductor layer is connected to each of the metal plugs. The first metal conductor layer is connected, and an interlayer insulating film is coated on the first metal conductor layer. Through the drain connection opening provided in the interlayer insulating film located on the metal plug connected to the drain region, the first metal conductor layer is covered. The second metal conductor layer for drain is commonly connected to each of the first metal conductor layers for drain among the metal conductor layers of A second metal conductor layer for source is connected in common to each of the first metal conductor layers for source among the first metal conductor layers through the opened source connection opening, and the interlayer insulating film The second metal conductor layer for the gate is commonly connected to the first metal conductor layer for the gate among the first metal conductor layers through the gate connection opening provided in The second metal conductor layer has a bonding pad portion for the drain, and the second metal conductor layer for the gate has a bonding pad portion for the gate.

  (55) In (54), the semiconductor layer is formed on a surface of a semiconductor substrate, and a source electrode is provided on the back surface of the semiconductor substrate.

  (56) In the above (55), a through layer having the same conductivity type as the semiconductor layer reaching the semiconductor substrate and having a higher impurity concentration than the semiconductor layer is provided in the semiconductor layer, and the main surface of the through layer The first metal conductor layer for the source is connected via a metal plug.

  (57) In the above (56), the source second metal is connected to the source first metal conductor layer through the source connection opening provided in the interlayer insulating film located on the metal plug. A metal conductor layer is connected.

  (58) In the above (56), the second metal conductor layer for source has a source pad portion for probe.

  (59) In the above (56), the extension portion of the second metal conductor layer for the source is disposed in the vicinity of the drain pad portion, and is located under the extension portion, Another through layer having the same configuration is provided in the semiconductor layer, and the extension portion is electrically connected to the other through layer.

  (60) In the above (56), a second metal conductor layer for a source different from the second metal conductor layer for the source is disposed in the vicinity of the gate pad portion, and the second source for the different source is arranged. Another through layer having the same configuration as that of the through layer is provided in the semiconductor layer, and the second metal conductor layer for the different source is provided in the other through layer. Is electrically connected.

  (61) In (59), the first metal conductor layer for the gate is disposed along the conductor layer for the gate electrode, and the first metal conductor layer for the drain and the first metal conductor layer for the source are arranged. The metal conductor layer is disposed along the first metal conductor layer for the gate, and the second metal conductor layer for the drain is located on the first metal conductor layer for the drain and is used for the drain. The second metal conductor layer for the source is located on the first metal conductor layer for the source and is located on the first metal conductor layer for the source. Are arranged along.

  (62) A plurality of channel regions on the main surface of a semiconductor chip having a semiconductor layer, a drain region and a source region provided across the channel regions, and a gate insulating film on the surface of each channel region An insulated gate semiconductor device having a gate electrode conductor layer provided, wherein a metal plug is connected to a main surface of each drain region and each source region, and a first plug is connected to each metal plug. A metal conductor layer is connected, an interlayer insulating film is coated on the first metal conductor layer, and is located on the metal plug connected to the drain region, through a drain connection opening provided in the interlayer insulating film. The second metal conductor layer for drain is commonly connected to the first metal conductor layer for drain in the first metal conductor layer. The second metal conductor layer for the source is commonly connected to the first metal conductor layer for the source among the first metal conductor layers through the source connection opening provided in the interlayer insulating film. And the second metal conductor layer for the gate is common to the first metal conductor layer for the gate among the first metal conductor layers through the gate connection opening provided in the interlayer insulating film. The second metal conductor layer for drain has a bonding pad portion for drain, and the second metal conductor layer for gate has an insulated gate field effect transistor having a bonding pad portion for gate. As a unit block, a plurality of insulated gate field effect transistors of the unit block are arranged on the main surface of the semiconductor chip.

  (63) In the above (62), the semiconductor chip has a first side and a second side facing each other, and a plurality of the insulated gate field effect transistors of the unit block are the first and second sides. The drain bonding pad portion is disposed along the first side, and the gate bonding pad portion is disposed along the second side.

  (64) In the above (63), the source second metal conductor layer has a probe source pad, and the probe source pad portion in the unit block is arranged along the second side. Yes.

  (65) In the above (63), the gate protection elements are electrically connected to the bonding pads for the gate arranged on the outermost side.

  (66) In the above (65), a metal connection layer of the same layer as the first metal conductor layer is formed on the main surface of the semiconductor chip, and the gate protection element and the bonding pad portion are connected by the metal connection layer. Has been.

  (67) A plurality of channel regions on a main surface of a semiconductor substrate having a semiconductor layer, a drain region and a source region provided across the channel regions, and a gate insulating film on the surface of each channel region In an insulated gate semiconductor device having a gate electrode conductor layer provided, a metal plug is connected to a main surface of each drain region and each source region, and a first metal is connected to each metal plug. A conductor layer is connected, an interlayer insulating film is coated on the first metal conductor layer, and the drain connection opening provided in the interlayer insulating film is located on the metal plug connected to the drain region, A second metal conductor layer for drain is commonly connected to each first metal conductor layer for drain among the first metal conductor layers, Through the source connection opening provided in the interlayer insulating film, the second metal conductor layer for the source is connected in common to each first metal conductor layer for the source among the first metal conductor layers. The second metal conductor layer for the gate is commonly connected to the first metal conductor layer for the gate among the first metal conductor layers through the gate connection opening provided in the interlayer insulating film. The second metal conductor layer for drain has a bonding pad portion for drain, and the second metal conductor layer for gate has a unit of an insulated gate field effect transistor having a bonding pad portion for gate. A plurality of insulated gate field effect transistors of the unit block are arranged on the main surface of the semiconductor substrate, and the first metal conductor for the gate is interposed between the unit blocks. A layer and the second metal conductor layer for the gate is connected.

  (68) A plurality of channel regions on a main surface of a semiconductor substrate having a semiconductor layer, a drain region and a source region provided across each channel region, and a gate insulating film on the surface of each channel region In an insulated gate semiconductor device having a gate electrode conductor layer provided, a metal plug is connected to a main surface of each of the drain region and the source region, and a first metal conductor is connected to the metal plug. Layers are connected, an interlayer insulating film is coated on the first metal conductor layer, and the drain connection opening provided in the interlayer insulating film is located on the metal plug connected to the drain region, The second metal conductor layer for drain is commonly connected to each first metal conductor layer for drain of the first metal conductor layer. Through the gate connection opening provided in the interlayer insulating film, the second metal conductor layer for the gate is commonly connected to the first metal conductor layer for the gate among the first metal conductor layers. The second metal conductor layer for drain has a bonding pad portion for drain, the second metal conductor layer for gate has a bonding pad portion for gate, and the drain region is the channel region. A common drain region sandwiched between the gate electrode conductor layers is provided independently.

  (69) An insulated gate semiconductor device according to the present invention includes a plurality of channel regions on each main surface of a semiconductor substrate having a semiconductor layer, and a drain region and a source region provided across the channel regions, First and second insulated gate field effect transistors having first and second insulated gate field effect transistors each having a gate electrode conductor layer provided on the surface of each channel region via a gate insulating film are disposed. A first resistor for impedance matching is electrically connected to each drain region of each of the first and second insulated gate field effect transistors, and a second resistor for impedance matching is electrically connected to each of the gate electrode conductor layers of the first and second insulated gate field effect transistors. Connected.

  (70) In (69), the first and second resistors are made of the same material as the gate electrode conductor layer.

  (71) In (69), a current detection element configured in the same manner as the first and second insulated gate field effect transistors is disposed on the main surface of the semiconductor substrate, and the first or second insulated gate type A shield layer is disposed between the field effect transistor and the current detection element.

  (72) In (71), the shield layer includes a semiconductor region reaching the semiconductor substrate from the main surface, a metal plug connected to the semiconductor region, and a first metal conductor connected to the metal plug. And a second metal conductor layer connected to the first metal conductor layer.

  (73) An insulated gate semiconductor device according to the present invention includes a plurality of channel regions on each main surface of a semiconductor substrate having a semiconductor layer, and a drain region and a source region provided across the channel regions, First and second insulated gate field effect transistors having gate electrode conductor layers provided on the surfaces of the respective channel regions via a gate insulating film are disposed, and the first and second insulating layers are disposed on the main surface. A drain bonding pad and a gate bonding pad for the gate type field effect transistor are disposed, a source electrode is disposed on the back surface of the semiconductor substrate, and a shield layer is disposed between the first and second insulated gate field effect transistors. Made up.

  (74) In (73), the shield layer includes a semiconductor region reaching the semiconductor substrate from the main surface, a metal plug connected to the semiconductor region, and a first metal conductor connected to the metal plug. And a second metal conductor layer connected to the first metal conductor layer.

  (75) A first conductivity type semiconductor substrate, a first conductivity type semiconductor layer formed on an upper surface of the semiconductor substrate, and a field insulating film formed to partition an element formation region on the main surface of the semiconductor layer. And first and second regions of a second conductivity type opposite to the first conductivity type, which are located in the element formation region and spaced apart from each other with a region where a channel is formed therebetween, and the second The region is composed of a low concentration region in contact with a region where a channel is formed and a high concentration region in contact with the low concentration region, a gate electrode formed on the channel region via a gate insulating film, and in the element formation region And forming the reach-through layer selectively on the main surface of the semiconductor layer in a method of manufacturing a semiconductor device having a first conductivity type reach-through layer formed in contact with the first region and the semiconductor substrate. Impure A step of selectively forming the field insulating film on the main surface of the semiconductor layer by thermal oxidation, extending the impurities, and forming the reach-through layer in contact with the semiconductor substrate; and the field insulation A step of forming the gate insulating film on the surface of the element forming region partitioned by the film, a step of forming the gate electrode on the gate insulating film, and then the first and second layers in the element forming region. And forming into two regions.

  (76) In the above (75), the thickness of the semiconductor layer is 2.5 μm or more and 3.5 μm or less.

  (77) In (75), after the field insulating film formation step, a first conductivity type impurity is introduced into the element formation region to form a well region as a region in which the channel is formed. .

  (78) In the above (77), the introduction of the impurity of the first conductivity type is performed by two-stage ion implantation.

  (79) In the above (75), after the field insulating film formation step, an annealing process is performed prior to the well formation.

  (80) In the above (75), the low concentration region is self-aligned with the gate electrode.

  (81) In the above (80), the low concentration region includes a first ion implantation step of introducing a second conductivity type impurity into the element formation region, and a first concentration higher than that of the first ion implantation. And a second ion implantation step for introducing two conductivity type impurities.

  (82) In (79), after the step of forming the gate electrode, a bird's beak oxide film is formed by thermal oxidation on the surface of the element formation region which is located below the end of the gate electrode and where the low concentration region is formed. Forming.

  (83) In (82), the gate electrode is formed of a polycrystalline silicon layer in contact with the gate insulating film, and the bird's beak oxide film is formed by thermally oxidizing an end portion of the polycrystalline silicon layer.

  (84) In the above (75), there is a step of forming a bird's beak oxide film by thermal oxidation on the surface of the element formation region located under both ends of the gate electrode after the step of forming the gate electrode.

  (85) In the above (84), the gate electrode is composed of a polycrystalline silicon layer in contact with the gate insulating film, and the bird's beak oxide film is formed by thermally oxidizing the end of the polycrystalline silicon layer.

  (86) In the above (75), in the step of forming the gate insulating film, an oxynitride film is formed by a heat treatment in an oxygen atmosphere containing nitrogen.

  (87) In any one of (82) and (84), the bird's beak oxide film is formed by thermal oxidation containing nitrogen.

  (88) In any one of (82) and (84), after forming the bird's beak oxide film, nitrogen ions are introduced into the bird's beak oxide film by an ion implantation method.

  (89) A method of manufacturing a semiconductor device according to the present invention includes the following steps.

  (a) a step of preparing a semiconductor substrate having a first conductivity type semiconductor layer on the main surface; and (b) a first conductivity type for forming a reach-through layer reaching the semiconductor substrate on the main surface of the semiconductor layer. A step of selectively introducing impurities, (c) a step of selectively forming a field insulating film for partitioning an element formation region on the main surface of the semiconductor layer by thermal oxidation, and (d) the field. A step of forming a gate insulating film on the surface of the element forming region partitioned by the insulating film; (e) a step of forming a gate electrode on the gate insulating film; and (f) a first conductive layer in the element forming region. (G) forming a first conductivity type first region self-aligned with respect to the gate electrode in the element formation region; Away from the above offset area And forming a first conductivity type second region having an impurity concentration higher than that of the offset region, and (h) forming a first insulating film so as to cover the element formation region. (I) forming an opening for exposing the first and second region main surfaces and the reach through layer main surface in the first insulating film, and (j) in the opening, Forming first, second, and third metal plugs connected to the first and second region main surfaces and the reach-through layer, respectively; and (k) first connecting the first and third metal plugs to each other. (1) forming a third conductor layer on the back surface of the semiconductor substrate; and (1) forming a third conductor layer on the back surface of the semiconductor substrate.

  (90) In the above (89), the back surface of the semiconductor substrate is ground prior to the step (l).

  (91) In the above (89), following the step (l), (m) a step of covering the first conductor layer and the second conductor layer with a second insulating film, and (n) the second step. Providing the insulating film with a first opening and a second opening, respectively, located on the first conductor plug and the second conductor plug, and (o) through the first opening. Patterning a first wiring layer connected to the first conductor layer and a second wiring layer connected to the second conductor layer through the second opening.

  (92) The step (89) includes a step of introducing a first conductivity type impurity and forming a well region prior to the step (e).

  (93) In the above (92), the well formation step is performed subsequent to the step (d).

  (94) In any of the above (92) or (93), the well formation step is performed by a two-stage ion implantation method.

  (95) In the above (89), the first insulating film in the step (h) is a silicon nitride film.

  (96) In the above (92), after the step (e), a first conductivity type impurity is ion-implanted into the well region from an oblique direction with respect to the main surface of the element formation region. Forming a buried region located in the region.

  (97) In the above (96), the buried region forming step uses the mask used for forming the first and second regions in the step (g).

  (98) In an insulated gate semiconductor device according to the present invention, an insulated gate field effect transistor is formed on the surface of a high resistance layer having the same conductivity type as that of the first conductivity type formed on the first conductivity type low resistance semiconductor substrate. An insulated gate semiconductor device formed, wherein a low-resistance source region of a second conductivity type opposite to the first conductivity type is formed in the high-resistance layer, and a low-resistance source region of the first conductivity type is formed. An offset structure connected to the low resistance substrate via a resistance layer, wherein the second conductivity type low resistance drain region of the semiconductor device is separated from the gate electrode end via the second conductivity type high resistance layer; The channel direction length of the gate electrode is 0.35 μm or less, the gate oxide film thickness is 10 nm or more and 12 nm or less, the offset length from the gate electrode end of the drain region is 0.4 μm or more and 0.8 μm or less, Resistance layer Saga 2.5μm or more and 3.5μm or less.

  (99) In the high-frequency module in which the amplifier circuit is configured by a plurality of semiconductor chips forming the insulated gate field effect transistor, each of the semiconductor chips includes a plurality of channel regions on a main surface of a semiconductor substrate having a semiconductor layer, A drain region and a source region provided across the channel region, and a gate electrode conductor layer provided on the surface of each channel region via a gate insulating film, and each of the drain region and the above A metal plug is connected to the main surface of each source region, a first metal conductor layer is connected to each of the metal plugs, an interlayer insulating film is coated on the first metal conductor layer, and the drain region is covered. Through the drain connection opening provided in the interlayer insulating film located on the connected metal plug, the first The second metal conductor layer for drain is commonly connected to each of the first metal conductor layers for drain among the metal conductor layers of one, and through the source connection opening provided in the interlayer insulating film, the above-mentioned The second metal conductor layer for the source is connected in common to the first metal conductor layer for the source among the first metal conductor layers, and through the gate connection opening provided in the interlayer insulating film, The second metal conductor layer for the gate is connected in common to the first metal conductor layer for the gate among the first metal conductor layers, and the second metal conductor layer for the drain is used for the drain And the second metal conductor layer for the gate has an insulated gate field effect transistor having a bonding pad portion for the gate as a unit block, and the insulated gate type electric power of the unit block. Effect transistors arranged in plural and in the semiconductor layer main surface.

  The present invention can be widely used in the manufacturing industry for manufacturing semiconductor devices.

DESCRIPTION OF SYMBOLS 1 ... P type low resistance Si substrate (semiconductor substrate), 2 ... P type high resistance Si epitaxial layer (semiconductor layer), 3 ... P type source punching region (reach through layer), 4 ... P type contact region, 5 ... P Type well region (punch through stopper layer PW), 6... Gate insulating film, 7... Gate electrode, 8... N type drain offset region (NM) having a low impurity concentration, 9. DESCRIPTION OF SYMBOLS 10 ... N-type source region which has high impurity concentration, P1 ... Conductor plug, 20 ... 1st insulating film (interlayer insulating film), M1 ... Conductor layer (1st layer wiring), 30 ... 2nd insulating film (interlayer insulating film) ), M2 ... wiring layer (second layer wiring), 40 ... surface protective film, S1 ... source electrode (wiring), S2 ... back source electrode.

Claims (9)

A semiconductor device including a power MISFET formed on a first conductivity type semiconductor substrate,
The power MISFET is
A gate insulating film formed on the semiconductor substrate;
A gate electrode formed on the gate insulating film;
A drain region and a source region formed on the semiconductor substrate and having a second conductivity type opposite to the first conductivity type;
A channel region formed in the semiconductor substrate between the source region and the drain region, and formed in the semiconductor substrate under the gate electrode;
A drain offset region of the second conductivity type formed in the semiconductor substrate between the gate electrode and the drain region and having a lower impurity concentration than the drain region;
A semiconductor device, wherein a field plate is provided on the drain offset region so as to overlap the drain offset region in a plan view and is fixed at a ground potential. A semiconductor device including a power MISFET formed on a first conductivity type semiconductor substrate,
The power MISFET is
A gate insulating film formed on the semiconductor substrate;
A gate electrode formed on the gate insulating film;
A drain region and a source region formed on the semiconductor substrate and having a second conductivity type opposite to the first conductivity type;
A channel region formed in the semiconductor substrate between the source region and the drain region, and formed in the semiconductor substrate under the gate electrode;
A drain offset region of the second conductivity type formed in the semiconductor substrate between the gate electrode and the drain region and having a lower impurity concentration than the drain region;
A semiconductor device, wherein a field plate is provided on the drain offset region so as to overlap with the drain offset region in a plan view and is fixed at the same potential as the source region. The semiconductor device according to claim 1 or 2,
The semiconductor device, wherein the field plate is formed along a gate width direction of the gate electrode. The semiconductor device according to claim 3.
The semiconductor device, wherein the field plate and the source region are electrically connected. The semiconductor device according to claim 4 further includes:
An interlayer insulating film formed on the semiconductor substrate so as to cover the power MISFET;
A first wiring layer formed on the interlayer insulating film and electrically connected to the drain region;
A second wiring layer formed on the interlayer insulating film and electrically connected to the source region;
The semiconductor device, wherein the field plate is formed in the same layer as the first wiring layer and the second wiring layer and is formed as a part of the second wiring layer. The semiconductor device according to claim 5 further includes:
A first metal plug and a second metal plug formed in the interlayer insulating film;
The first wiring layer and the drain region are connected via the first metal plug,
The semiconductor device, wherein the second wiring layer and the source region are connected via the second metal plug. The semiconductor device according to claim 6.
Each of the first wiring layer and the second wiring layer includes an aluminum alloy film,
The first metal plug and the second metal plug each include a tungsten film. The semiconductor device according to any one of claims 1 to 7,
The first conductivity type is P-type;
The semiconductor device according to claim 2, wherein the second conductivity type is an N type. The semiconductor device according to any one of claims 1 to 8,
A plurality of the power MISFETs are formed,
A semiconductor device, wherein the plurality of power MISFETs constitute a high frequency power amplifier circuit.

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