JP2001230260A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a layout area of a semiconductor device where a transistor device and a diode element are subjected to wiring connection. SOLUTION: A diode is formed in a part of a collector lead-out part of a transistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a semiconductor device having a bipolar transistor, a diode element connected to the collector of the bipolar transistor, and a method of manufacturing the same.

2. Description of the Related Art Hereinafter, in the description of the prior art in the specification, an NPN type compound semiconductor heterojunction bipolar HB will be described.
A description will be given taking a T transistor as an example. Compound HBT has a high frequency of 10G due to its excellent high-frequency characteristics and high current drive capability.
Microwave and millimeter-wave monolithic integrated circuits (MMI) including ultra-high-frequency analog ICs for optical communication exceeding b / s, ultra-high-speed digital ICs, and high-output devices for mobile phones
It is applicable to the component C). By the way, the HBT has a relatively strong collector-emitter voltage dependence in its high-frequency characteristics. However, in the HBT integrated circuit, it is necessary to bias the collector-emitter voltage to an optimum voltage in order to maximize the high-speed operation of the transistor. is there. Therefore, using a diode for level shift, the collector
Adjust the voltage between emitters. FIG. 4A is a circuit configuration diagram of an example in which a collector-base terminal of a transistor is short-circuited to form a base-emitter junction diode element, and the level is shifted by connecting to a collector terminal of the transistor. FIG. 5 shows an example in which a PN junction diode and a transistor element using the base-emitter junction of FIG. 4A are laid out according to a wiring rule. In the transistor element, an emitter-top type NPN-type HBT is formed in the intrinsic region 11 of the transistor, and the other semiconductor regions are increased in resistance by using hydrogen ion or boron ion implantation or the like. The emitter electrode 7, the base electrode 8, and the collector electrode 9 are connected to the wiring 12 through contact through holes, respectively. The diode element is formed by short-circuiting between the collector and base terminals of the transistor. The size of the PN diode using the base-emitter junction is similar to the size of the transistor element. Also, as shown in FIG. 4B, a PN diode using a base-emitter junction can be formed by removing an unnecessary collector electrode portion, but the structures of the intrinsic portions of the emitter and the base are almost the same. The size of the diode element is substantially the same as the size of the transistor element. FIG. 6 is a top view of a conventional transistor element as viewed from above. FIG. 7 is a sectional structural view of each part of the conventional transistor element shown in FIG. However, for readability,
The wiring 12 and the contact through hole 13 are omitted. FIG. 7A is a sectional structural view taken along the line aa ′ in FIG. This is a transistor portion, on a semiconductor substrate 6 made of GaAs, a collector contact layer 5 made of n ⁺ -type GaAs,
Collector layer 4 made of n-type GaAs, base layer 3 made of p + -type GaAs, emitter layer 2 made of n-type AlGaAs, n ⁺ -type InG
An emitter contact layer 1 made of aAs is formed, a collector electrode 19 made of AuGe-Ni-Au is formed on the collector contact layer 5, a base electrode 8 made of Ti-Pt-Au is formed on the base layer 3, and an emitter contact layer 1 is formed on the emitter contact layer 1. This is a mesa-type transistor element structure in which an emitter electrode 7 made of WSi is formed. FIG. 7C is a cross-sectional structural view taken along the line cc ′ in FIG. 6, and FIG. 7B is a cross-sectional structural view taken along the line bb ′ in FIG. In this structure, since the collector is in the lower layer, a collector lead portion is required to connect the collector and the upper wiring. In this case, the collector contact layer 5 and the collector electrode 19 correspond to a collector lead portion. When a diode using a base-collector junction or a Schottky contact diode is newly manufactured, a part of a vertical HBT epitaxial layer structure is used for the diode, so that a portion of the diode drawn from the lower layer is used. An additional area is required, and it is difficult to reduce the effective element size of the diode element.

As described above, in the layout example of the level shift diode element and the transistor circuit shown in FIG. 5, diode elements having a size substantially equal to that of the transistor are connected by wiring according to the wiring rule. Is the size of the transistor element 2
Requires twice or more area. This leads to an increase in chip size. In an HBT circuit aiming at high-speed operation, the length of wiring becomes long, so that a wiring delay due to an increase in wiring length increases, and high-speed operation of the circuit is hindered. As described above, a level shift diode is used to maximize the speed of the transistor.However, since the size of the diode element is not smaller than that of the transistor element, the chip size increases and the wiring length increases, There is a trade-off relationship that the high-speed performance of the circuit is hindered by the wiring delay.

According to the present invention, there is provided a semiconductor device comprising:
In a semiconductor device having a bipolar transistor and a diode element connected to a collector of the bipolar transistor, the semiconductor device has a collector leading portion drawn from the collector, and a part of the collector leading portion has a diode structure. . further,
It is preferable that the collector lead portion couples the collector with an upper wiring. Further, the bipolar transistor has a collector layer, a base layer,
It is desirable that the layers are stacked in the order of the emitter layer. Preferably, the diode structure is a Schottky contact diode. Further, it is desirable that the Schottky contact diode is formed by Schottky junction of a metal layer on a region where a part of the collector layer is insulated and separated by increasing the resistance by ion implantation. Alternatively, the diode structure is preferably a PN junction diode.
Further, the PN junction diode may be formed by growing a semiconductor layer of a conductivity type opposite to that of the collector layer on a region where a part of the collector layer is insulated and separated by increasing the resistance by ion implantation. desirable. The method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device having a bipolar transistor and a diode element connected to a collector of the bipolar transistor, wherein a part of the collector layer of the bipolar transistor is made to have a high resistance by ion implantation. The method includes a step of insulating and isolating, and a step of forming a Schottky contact diode by Schottky bonding a metal layer on the insulated area. Another method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device having a bipolar transistor and a diode element connected to a collector of the bipolar transistor, wherein a part of the collector layer of the bipolar transistor is formed by ion implantation. A step of forming a PN junction diode by growing a semiconductor layer having a conductivity type opposite to that of the collector layer on the region where the insulation is separated, by increasing the resistance. According to the semiconductor device of the present invention, since the diode is formed in a part of the collector lead-out portion of the transistor element, the transistor element and the diode element can be formed in the area of one transistor element, and the layout area of the element can be reduced. It is possible to reduce the wiring length and the wiring length, which is advantageous for high-speed operation of the circuit.

BEST MODE FOR CARRYING OUT THE INVENTION In the following description of embodiments, an NPN type H of an emitter top type is used as a transistor element.
A description will be given using BT as an example. FIG. 1 is a top view of an HBT transistor element including a diode element in a part of a collector lead-out portion according to a first embodiment of the present invention, as viewed from above. The intrinsic region of the transistor and the intrinsic region of the Schottky contact diode are regions 11 in which high resistance ion implantation is not performed, and the other semiconductor regions are increased in resistance using hydrogen ion implantation, boron ion implantation, or the like. The intrinsic region of the transistor and the intrinsic region of the Schottky contact diode are electrically separated from each other by a semiconductor region having increased resistance, and are connected to each other by a collector electrode 9. The Schottky contact diode is formed from the Schottky electrode 15 and the semiconductor layer thereunder. Although not shown, the HBT transistor element and the Schottky contact diode are covered at the top with an insulating film, and the base electrode 8, the emitter electrode 7, and the Schottky electrode 15 have contact through holes 13 formed in the insulating film. The wiring 12 is connected by gold plating or the like. FIG. 2 is a sectional structural view of each part of the HBT transistor element including a diode element in a partial region of the collector lead-out part shown in FIG. However, in order to make it easier to see, the wiring 12 and the contact through hole 1
3 is omitted. FIG. 2A is a sectional structural view taken along the line aa ′ in FIG. This is the intrinsic part of the transistor, Ga
On a semiconductor substrate 6 made of As, a collector contact layer 5 made of n + type GaAs, a collector layer 4 made of n-type GaAs, p + type G
A base layer 3 composed of aAs, an emitter layer 2 composed of n-type AlGaAs, and an emitter contact layer 1 composed of n + -type InGaAs are sequentially formed. On the collector contact layer 5, a collector electrode 9 composed of AuGe-Ni-Au is formed. A base electrode 8 made of Ti-Pt-Au is formed on the base layer 3 with the emitter layer 2 or the emitter contact layer 1 and a side wall of the emitter insulating film made of SiO ₂ therebetween, and the emitter contact layer 1 made of n + type InGaAs is formed.
On which a emitter electrode 7 made of WSi is formed. FIG. 2 (c) is the same as FIG.
It is sectional drawing of the -c 'part. This is a structural diagram of a Schottky contact diode formed in a partial area of a collector lead portion of a transistor. An electrode metal 15 made of WSi is formed by Schottky contact on a collector layer 4 made of n-type GaAs to form a Schottky contact diode. An ohmic electrode is formed on the collector contact layer 5 made of n + -type GaAs by the collector electrode metal 9, and the intrinsic portion of the transistor is connected to the Schottky contact diode through the collector electrode metal 9. FIG. 2B is a sectional structural view taken along the line bb ′ of FIG.
FIG. 2 is a structural view of a transistor and a diode, wherein an intrinsic portion of the transistor and an intrinsic portion of the diode are electrically separated by a region 10 whose resistance is increased by ion implantation. In the structure according to the present invention, the collector lead portion connecting the collector layer 4 and the upper wiring 12 is composed of the collector contact layer 5 of the transistor intrinsic portion, the collector electrode metal 9, the collector contact layer 5 of the diode intrinsic portion, and the Schottky contact diode element. It is composed of That is, the diode element is formed in a part of the collector lead portion. According to this structure, the occupied area can be greatly reduced as compared with the conventional case where the transistor and the diode are separately formed and the lead portions from the respective lower layers are connected by the wiring metal by the photoresist process. FIG. 3 shows a second embodiment of the present invention. The difference from the first embodiment is that a part of the diode element in the collector lead portion of the transistor is formed on the collector layer 4 made of n-type GaAs by using a selective regrowth process to form a regrown layer 16 made of p-type GaAs. To form a PN junction diode. The cross-sectional structural view taken along the line aa ′ in FIG. 3A is the intrinsic portion of the transistor, and is similar to the line aa ′ in FIG. FIG.
In the cross-sectional structure taken along the line cc ′ in (c), the P-type semiconductor layer 16 is regrown on the N-type collector layer 4 by a selective regrowth process, and Ti-Pt-Au that can make ohmic contact with the P-type semiconductor is used. The ohmic electrode metal 17 is formed to form a PN junction diode. In the second embodiment, an N-type semiconductor region can also be manufactured by a selective regrowth process.
The level shift voltage of the diode element is represented by the on-voltage of the diode, and the forward on-voltage for energizing the PN junction diode is the number of current ranges normally used in IC circuits (current range from mA to tens of mA). Is expressed as follows by the diffusion potential (Φ _D ) of the PN semiconductor. _{Φ D = (kT / q)} · lN (N A · N D / N i 2) ( Equation 1) (N _A is the acceptor concentration, N _D is the donor concentration, N _i is the intrinsic carrier concentration.) From this The level shift voltage can be adjusted and set by the doping concentration of the regrown N-type semiconductor layer and the doping concentration of the P-type semiconductor layer, and the element setting voltage of the integrated circuit using the present element structure can be finely adjusted. This is advantageous for high-speed operation.

According to the present invention, when wiring a diode element which is not much different from the size of a conventional transistor element, a layout area twice or more as large as that of the transistor is required. Can be formed, a transistor element and a diode element can be formed with a layout area for one transistor element. As described above, since the layout area of the transistor element and the diode element can be reduced to 1/2 or less, the chip size and the length of the connection wiring with other elements can be reduced, which is very useful for increasing the speed of an IC using this element structure. It is advantageous.

[Brief description of the drawings]

FIG. 1 is a top view of an HBT transistor element including a diode element in a partial region of a collector lead-out portion according to the present invention as viewed from above.

FIG. 2 is a sectional structural view of a first embodiment of an HBT transistor element including a Schottky contact diode in a part of a collector lead-out portion according to the present invention;

FIG. 3 is a sectional structural view of a second embodiment of an HBT transistor element including a diode element in a partial region of a collector lead-out portion according to the present invention;

FIG. 4 is a circuit configuration diagram of a bipolar transistor using a level shift diode.

FIG. 5 shows an HB using a conventional level shift diode.
Top view of T transistor element viewed from above

FIG. 6 is a top view of a conventional HBT transistor element viewed from above.

FIG. 7 is a sectional structural view of a conventional HBT transistor element.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Emitter contact layer 2 Emitter layer 3 Base layer 4 Collector layer 5 Collector contact layer 6 Semiconductor substrate 7 Emitter electrode 8 Base electrode 9, 19 Collector electrode 10 Semiconductor region whose resistance has been increased by ion implantation 11 High device defining element intrinsic region Regions where resistive ion implantation is not performed 12 Wiring 13 Contact through hole 14 Emitter insulating film side wall 15 Schottky electrode 16 Regrowth layer 17 Ohmic electrode 20, 30 Forward terminal of diode 21, 31 Collector terminal 22, 32 Base terminal 23, 33 Emitter terminal

Claims (9)

[Claims] In a semiconductor device having a bipolar transistor and a diode element connected to a collector of the bipolar transistor, the semiconductor device has a collector lead portion drawn from the collector, and a part of the collector lead portion has a diode structure. A semiconductor device characterized by the above-mentioned. 2. The semiconductor device according to claim 1, wherein said collector lead portion connects said collector with an upper wiring. 3. The semiconductor device according to claim 1, wherein said bipolar transistor is laminated on a semiconductor substrate in the order of a collector layer, a base layer, and an emitter layer. 4. The semiconductor device according to claim 1, wherein said diode structure is a Schottky contact diode. 5. The Schottky contact diode according to claim 1, wherein a metal layer is formed by Schottky junction on a region where a part of the collector layer is insulated and separated by high resistance by ion implantation. Item 5. The semiconductor device according to item 4. 6. The semiconductor device according to claim 1, wherein said diode structure is a PN junction diode. 7. The PN junction diode is formed by growing a semiconductor layer having a conductivity type opposite to that of the collector layer on a region where a part of the collector layer is insulated and separated by increasing resistance by ion implantation. 7. The semiconductor device according to claim 6, wherein: 8. A method for manufacturing a semiconductor device having a bipolar transistor and a diode element connected to the collector of the bipolar transistor, wherein a part of the collector layer of the bipolar transistor is insulated and separated by increasing the resistance by ion implantation. Forming a Schottky contact diode by Schottky bonding a metal layer on the insulated region. 9. A method for manufacturing a semiconductor device having a bipolar transistor and a diode element connected to a collector of the bipolar transistor, wherein a part of a collector layer of the bipolar transistor is insulated and separated by increasing resistance by ion implantation. Growing a semiconductor layer of the opposite conductivity type to the collector layer on the insulated region to form a PN junction diode.