JP6605977B2 - Semiconductor integrated circuit and manufacturing method of semiconductor integrated circuit - Google Patents

Description

  The present invention relates to a semiconductor integrated circuit of a transistor and a diode corresponding to a high frequency band, and improves the reliability of the diode, and can stably form a contact hole of a wiring electrode connecting a minute base electrode. It is characterized by that.

  As a high-frequency band amplifier or signal generator, a structure in which diodes and transistors are integrated on the same semiconductor substrate is known.

JP 2013-110300 A

  FIG. 42 shows a semiconductor integrated circuit 10 in which a varactor diode and a heterojunction bipolar transistor are integrated on the same semiconductor substrate as a variable frequency signal generator, with some components omitted. In this semiconductor integrated circuit 10, a layer 13b, which is a substantial part of a varactor diode, is grown on the HBT layer 12 and the layer 13a below the cathode contact layer of the varactor diode. It is manufactured by adding a varactor diode manufacturing process to the HBT manufacturing process, and the layer structure of the transistor and the varactor diode can be uniquely optimized. However, the structure of the conventional semiconductor integrated circuit 10 has the following problems.

  The semiconductor integrated circuit shown in FIG. 42 includes a semiconductor substrate 11 and a collector contact layer 12a, a collector layer 12b, a base layer 12c, an emitter layer 12d, an emitter contact layer 12e, and a lower layer portion of a varactor diode. The collector contact layer 13a, the collector layer 13b, the base layer 13c, the emitter layer 13d, the cathode contact layer 13e, and the cathode layer 14a constituting the substantial part of the varactor diode, and the anode contact layer are included. Furthermore, a cathode electrode 15a is formed on the cathode contact layer, an anode electrode 15b is formed on the anode contact layer, a collector electrode 15c is formed on the collector contact layer, a base electrode 15d is formed on the base layer, and an emitter electrode 15e is formed on the emitter contact layer. Have . An inorganic film 16 is formed so as to cover the cathode layer 14a and the anode contact layer 14b, an organic film 17a is formed so as to protect the side surface of the emitter layer, and further, the surface on which the organic film 17a and the remaining semiconductor are exposed is protected. Thus, the organic film 17b is formed.

  In FIG. 42, wiring electrodes 19a, 19b, 19c, 19d, and 19e indicated by broken lines are organic films 17a such as benzocyclobutene (hereinafter referred to as BCB) for protecting elements formed so as to cover the entire surfaces of the transistor and the varactor diode. , 17b are connected to the cathode electrode 15a, the anode electrode 15b, the base electrode 15c, the collector electrode 15d, and the emitter electrode 15e through contact holes 18a, 18b, 18c, 18d, and 18e. In order of increasing electrode height, there are an anode electrode 15a, a cathode electrode 15b, an emitter electrode 15e, a base electrode 15d, and a contact electrode 15c.

  A contact hole connecting the wiring electrode to each electrode is formed by etching. In general, if the thickness of the film to be etched is thick, the etching time becomes long, so that the etching progresses not only in the height direction but also in the width direction, and a contact hole having a dimension w + Δw larger than the dimension w of the base electrode Will be obtained. This is the effect of so-called side etching. The upper surface of the organic film for element protection in which the collector hole is formed is higher than the anode electrode and the cathode electrode at the highest position among the electrodes. Since the base and collector electrodes of the transistor are positioned lower than the anode and cathode electrodes, the organic film on the base and collector electrodes is thicker than the organic film on the anode and cathode electrodes of the diode. Will be. Therefore, it takes a long time to form the contact holes for the collector electrode and the base electrode, and there is a problem that the opening width of the contact holes for the base electrode and the collector electrode is widened with an increase in the amount of side etching.

  In particular, when the diameter of the contact hole of the base electrode increases, the width of the contact hole becomes larger than the width of the base electrode. When the base electrode is connected by wiring in this state, the width of the contact hole of the base electrode is larger than the width of the base electrode, so that the previously formed base electrode has a size that is slightly larger. When the size of the base electrode increases, the thickness of the organic film that secures insulation with the emitter electrode next to the base electrode becomes thinner by one increase in the size of the base electrode, and good insulation cannot be maintained. . Therefore, the probability of occurrence of an element that tends to short-circuit between the emitter electrode and the base electrode is increased. In order to avoid a short circuit between the emitter electrode and the base electrode, it is conceivable to increase the distance between the emitter electrode and the base electrode. However, as the distance between the base electrode and the emitter electrode increases, the width of the base layer increases. When the width of the base layer is increased, the value of the base collector capacitance defined by the width of the base layer is increased, so that the band determined by the CR time constant is lowered and the desired high frequency characteristics cannot be obtained.

  As a method for solving this problem, a BCB having a thickness of about 5 μm is applied to the entire surface, and the step between the collector electrode and the base electrode is reduced by using an etch-back method by overall etching. There is also a method that makes it possible to form a very small base electrode contact hole by optimizing the thickness of the organic film on the substrate. When the entire surface of the thick BCB formed on the entire surface is etched by the etch back method, the organic films on the anode and cathode electrodes are all removed first, and then the organic film on the base electrode is removed. The thickness is partially removed by etching, and the thickness becomes optimum for forming a contact hole of the base electrode. However, at this time when the thickness of the organic film on the base electrode is optimized, the protective film on the semiconductor side surface is excessively etched on the diode side, the semiconductor side surface is exposed, and the semiconductor side surface is further etched. It becomes. For this reason, the semiconductor forming the diode is damaged by the etching, and the reliability of the diode is lowered. In addition, when etching is performed so as to leave all the protective film on the side surface of the semiconductor, the organic film on the base electrode remains thick on the contact, and a contact hole for connecting the base electrode and the wiring electrode is widely formed. Therefore, insulation between the emitter electrode and the base electrode cannot be ensured.

  An object of the present invention is to solve this problem and to stably form a contact hole of a wiring electrode for connecting a minute base electrode without impairing the reliability of the diode.

In order to achieve the above object, a semiconductor integrated circuit according to claim 1 of the present invention comprises:
A semiconductor substrate (21);
A diode (20) comprising a first hierarchical structure (22) on the semiconductor substrate;
A semiconductor integrated circuit having a transistor (30) including a second hierarchical structure (31) on the semiconductor substrate;
The first hierarchical structure (22) has a cathode layer (280) and an anode contact layer (290) on the cathode layer;
The second hierarchical structure includes a collector contact layer (330), a collector layer (340) over the collector contact layer, a base layer (350) over the collector layer, and an emitter layer (360) over the base layer. And an emitter contact layer (370) on the emitter layer,
In a semiconductor integrated circuit having an emitter electrode (46) on the emitter contact layer, a base electrode (42) on the base layer, and a collector electrode (41) on the collector contact layer,
A first inorganic film (202) covering side surfaces of the cathode layer and the anode contact layer;
A first organic film (306) covering a side surface of the emitter layer and the base electrode, and further covering between the base electrode and the emitter electrode;
A second organic film (111) covering the collector electrode,
The height of the upper surface of the anode contact layer is higher than the height of the upper surface of the emitter contact layer,
The height of the upper surface of the first organic film is lower than the height of the upper surface of the first inorganic film, and is not more than the height of the upper surface of the emitter electrode,
It further has a wiring electrode (542) connected to the base electrode through a contact hole formed in the first organic film.

A semiconductor integrated circuit according to claim 2 of the present invention is the semiconductor integrated circuit according to claim 1,
The height of the upper surface of the second organic film is lower than the height of the upper surface of the first organic film.

The semiconductor integrated circuit as in claim 3 of the present invention is a semiconductor integrated circuit according to claim 1 or claim 2,
The height of the upper surface of the collector electrode is equal to the height of the upper surface of the base electrode.

The semiconductor integrated circuit according to claim 4 of the present invention is a semiconductor integrated circuit according to any one of claims 1 to 3,
Having an anode electrode on the anode contact layer;
The height of the upper surface of the anode electrode is equal to the height of the upper surface of the emitter electrode.

The semiconductor integrated circuit according to claim 5 of the present invention is a semiconductor integrated circuit according to any one of claims 1 to 4,
The first hierarchical structure further includes a cathode contact layer under the cathode layer,
Having a cathode electrode on the cathode contact layer;
The cathode electrode and the emitter electrode are equal in height.

The semiconductor integrated circuit according to claim 6 of the present invention is a semiconductor integrated circuit according to any one of claims 1 to 5,
The layer structure below the cathode layer of the first hierarchical structure is the same as that of the second hierarchical structure.

The semiconductor integrated circuit according to claim 7 of the present invention is a semiconductor integrated circuit according to any one of claims 1 to 6,
It has a fourth inorganic film formed so as to cover the upper surface of the first organic film and the upper surface of the second organic film.

The semiconductor integrated circuit according to claim 8 of the present invention is a semiconductor integrated circuit according to any one of claims 1 to 7, and the side surface of the first organic layer side of the collector layer It further has a third inorganic film (309) to be covered.

A semiconductor integrated circuit according to claim 9 of the present invention is the semiconductor integrated circuit according to claim 8,
An element isolation part (70) that is an area between the first hierarchical structure and the second hierarchical structure and includes an element isolation position (71);
A second inorganic film (209) covering a side surface of the layer below the cathode layer and a region of the element isolation portion on the diode side in the first hierarchical structure;
The third inorganic film further covers from the surface of the collector electrode to the element isolation region on the transistor side,
The second inorganic film and the third inorganic film include a material having a lower etching rate than the first organic film and the second organic film,
The thickness of the material having an etching rate lower than that of the first organic film and the second organic film included in the second inorganic film is the first organic film included in the third inorganic film and 9. The semiconductor integrated circuit according to claim 8, wherein the thickness of the material is lower than that of the material having an etching rate lower than that of the second organic film.

According to a tenth aspect of the present invention, there is provided a semiconductor integrated circuit manufacturing method comprising: a collector contact layer (130), a collector layer (140), a base layer (150), an emitter layer (160), an emitter included in a transistor on a semiconductor substrate; Epitaxially growing a contact layer (170), a cathode layer (180) included in a diode, and an anode contact layer;
The cathode layer (280) and anode contact layer (290) of the diode, and the collector contact layer (330), collector layer (340), base layer (350), emitter layer (360), emitter contact layer (370) of the transistor. ) By etching,
In a method for manufacturing a semiconductor integrated circuit of a transistor and a diode that form an anode electrode, a collector electrode, a base electrode, and an emitter electrode,
Forming a first inorganic film so as to cover the side surface of the cathode layer (steps 7 and 8);
Forming a first organic film so as to cover the side surface of the emitter layer and the base electrode, and further cover between the base electrode and the emitter electrode (steps 10 and 11);
Forming a second inorganic film so as to cover the first inorganic film (step 14);
Forming a second organic film so as to cover the entire surface from the second inorganic film to the first organic film (step 18);
The second inorganic film includes a material having an etching rate lower than that of the first organic film and the second organic film,
Starting the entire etching of the second organic film;
The entire surface is etched until the height of the first organic film is higher than that of the base electrode and lower than the height of the emitter electrode (step 19).
Forming a contact hole in the first organic film (step 21);
A wiring electrode connected to the base electrode through the contact hole is formed (step 22).

A semiconductor integrated circuit manufacturing method according to claim 11 of the present invention is the semiconductor integrated circuit manufacturing method according to claim 10,
After forming the second inorganic film (step 14),
Forming a third inorganic film so as to cover the upper surface of the first organic film (steps 15, 16, and 17);
The third inorganic film includes a material having an etching rate lower than that of the first organic film and the second organic film, and the first organic film and the second organic film included in the second inorganic film. The material having a lower etching rate than the organic film is thicker than the material having a lower etching rate than the first organic film and the second organic film included in the third inorganic film.
The etching of the entire surface of the second organic film is started.

  In the semiconductor integrated circuit of the present invention, the side surfaces of the cathode layer and the anode contact layer of the diode are covered with an inorganic film, and the height of the upper surface of the organic film covering the base electrode is equal to or less than the height of the upper surface of the emitter electrode; The structure is lower than the height of the upper surface of the inorganic film covering the side surfaces of the cathode layer and the anode contact layer of the diode. Since the side surfaces of the cathode layer and the anode contact layer of the diode are covered with the inorganic film, the reliability of the diode is not lowered. Furthermore, by adopting a configuration in which the upper surface of the organic film covering the base electrode is less than or equal to the height of the upper surface of the emitter electrode, the organic film forming the contact hole of the wiring electrode can be made thinner, and the influence of side etching It is possible to prevent the contact hole of the base electrode from expanding due to. Therefore, a contact hole for connecting the base electrode and the wiring electrode can be stably formed in the organic film on the base electrode, and insulation between the emitter electrode and the base electrode can be ensured.

  Further, by forming an inorganic film containing a material having a higher etching rate than the organic film on the organic film on the base electrode before the entire surface etching, the organic film covering the base electrode is excessively etched. This can be prevented.

  Further, by making the upper surface of the collector electrode and the upper surface of the base electrode the same height, the step between the upper surface of the organic film covering the collector electrode and the upper surface of the organic film covering the base electrode can be reduced, and the contact of the base electrode It is possible to apply a resist at the time of forming the wiring of the hole to a surface that is more flat. Therefore, the size distribution of the contact hole of the base electrode can be further suppressed.

  In addition, the base film and emitter electrode at the time of manufacture are protected by providing an organic film on the collector electrode that covers the side surface of the collector layer and an inorganic film that directly protects the side surface of the collector layer between the side surfaces of the collector layer. It is possible to prevent the organic film from absorbing moisture during manufacturing, and to prevent damage when the collector layer side surface is excessively etched. As a result, the reliability of the transistor can be further improved.

  Further, the inorganic film covering the side surface of the collector layer was extended so as to cover a part of the region where the surface of the semiconductor substrate between the transistor and the diode was exposed via the collector electrode. Furthermore, an inorganic film that directly protects from the side of the inorganic film that protects the cathode electrode to the part on the diode side in the region where the surface of the semiconductor substrate between the transistor and the diode is exposed via the side of the lower layer of the diode is provided. It was. Further, in the region where the surface of the semiconductor substrate between the transistor and the diode is exposed, the thickness of the inorganic film in the part on the diode side is made larger than the thickness of the inorganic film covering the part on the transistor part side. With this configuration, it is possible to protect the exposed surface of the semiconductor, such as the surface of the semiconductor substrate and the side surface of the collector contact layer of the diode or transistor, thereby further improving the reliability of the diode or transistor. Can be made.

  Further, as another effect of making the height of the base electrode and the collector electrode the same, the depth of the contact hole of the collector electrode becomes shallower, and it is possible to prevent disconnection of the electrode during wiring formation.

  Further, in the manufacturing method of the present invention, the etching rate is higher than the organic film covering the diode and the transistor in the inorganic film covering the anode electrode and the cathode electrode of the diode and the inorganic film covering the organic film on the base electrode of the transistor at the start of the entire surface etching. Is selected to contain low material. Furthermore, the thickness of the material having a lower etching rate than the organic film included in the inorganic film covering the anode electrode and the cathode electrode is lower than that of the organic film included in the inorganic film covering the organic film on the base electrode. Set the thickness thin. By manufacturing the entire surface by the etch-back method under such conditions, the organic film on the collector electrode and the organic film on the base electrode can be set to a desired height without impairing the reliability of the diode. Can do. As a result, the base electrode contact hole can be stably formed.

Structure diagram of a semiconductor integrated circuit according to an embodiment of the present invention The figure for comparing the height of each electrode of the semiconductor integrated circuit of embodiment of this invention The figure which shows the structure before the whole surface etching of the semiconductor integrated circuit of FIG. The figure which shows the structure at the time of completion | finish of the whole surface etching of the semiconductor integrated circuit of FIG. The figure which shows transition of the height of the film | membrane on each electrode from the end time of the whole surface etching of the semiconductor integrated circuit of FIG. 1 to the end time Structural diagram of a semiconductor integrated circuit according to another embodiment of the present invention The figure which shows the structure before the whole surface etching of the semiconductor integrated circuit of FIG. The figure which shows the structure at the time of completion | finish of the whole surface etching of the semiconductor integrated circuit of FIG. Structural diagram of a semiconductor integrated circuit according to another embodiment of the present invention The figure which shows the structure before the whole surface etching of the semiconductor integrated circuit of FIG. The figure which shows the structure at the time of completion | finish of the whole surface etching of the semiconductor integrated circuit of FIG. Structural diagram of a semiconductor integrated circuit according to another embodiment of the present invention The figure which shows the structure before the whole surface etching start of the semiconductor integrated circuit of FIG. The figure which shows the structure at the time of completion | finish of the whole surface etching of the semiconductor integrated circuit of FIG. The figure which shows the structure of the top view and sectional drawing of the semiconductor integrated circuit of FIG. The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the manufacturing process of the semiconductor integrated circuit of embodiment The figure which shows the flowchart of the manufacturing process of the semiconductor integrated circuit of embodiment. Diagram showing the configuration of the prior art

(First embodiment)
FIG. 1 shows a first embodiment. FIG. 1 shows an integrated circuit including a varactor diode 20 (varactor) and an npn heterobipolar transistor 30 (HBT) formed by etching a layer grown epitaxially on a semiconductor substrate 21 made of InP. Yes. In this figure, one HBT and one varactor are shown, but it is assumed that a large number of other semiconductor elements, coils, resistors, and capacitors are formed in an actual semiconductor integrated circuit.

  This semiconductor integrated circuit performs an etching process on a plurality of layers made of semiconductor crystals formed by epitaxial growth of semiconductor crystals on a semiconductor substrate made of InP. As a result, a varactor hierarchical structure 22 and an HBT hierarchical structure 31 are formed. The lower layer 22a of the varactor hierarchical structure 22 has the same layer structure as the HBT hierarchical structure 31. The semiconductor substrate is exposed in the region between the HBT body and the lower layer 22a of the varactor hierarchical structure, and this region is formed by removing all layers of semiconductor crystals formed by epitaxial growth by etching. Yes. It is assumed that the varactor and the HBT are separated from each other at a predetermined position in this region, and this region is referred to as an element isolation portion 70, and a position that is a boundary between the varactor and the HBT is referred to as an element isolation position 71.

  The HBT and the varactor are separated from each other at an element separation position 71 in the element separation portion. The varactor includes an element isolation portion on the lower layer side of the varactor with respect to the element isolation position 71, a lower layer portion and an upper layer portion of the varactor, and the HBT includes an element isolation portion on the HBT side and an actual part of the HBT. The upper layer part 22b formed on the lower layer part 22a of the hierarchical structure of the varactor has a function as an actual part of the varactor.

Since the lower layer 22a and the HBT 30 of the hierarchical structure of the varactor have a common layer structure, they will be described first. On the semiconductor substrate 21 made of InP, collector contact layers 230 and 330 with a total thickness of 270 nm are provided. The collector contact layers 230 and 330 include n ⁺ -InP and n ⁺ -InGaAs (indium gallium arsenide). The notation of “+” in the upper right of n ⁺ is used for a material in which impurities are heavily doped in p-type and n-type semiconductors. Here, the definition of high concentration is 3 × 10 ¹⁸ cm ⁻³ or more. And Further, since the layer structure of the lower part of the varactor is the same as that of the HBT, the same layer name will be given and described.

On the collector contact layer, collector layers 240 and 340 having a total thickness of 350 nm are formed. The collector layer includes n-InP, i-InP, i-InGaAs, and n-InGaAs. (Note that an HBT containing InP in the collector layer is called a double heterostructure bipolar transistor DHBT). Further, base layers 250 and 350 having a film thickness of 70 nm are formed on the collector layer and are made of p ⁺ -InGaAs.

An emitter layer 260, 360 having a total thickness of 70 nm is formed on the base layer. The emitter layer includes n-InGaAs and n-InP263 and 363. Furthermore, layers 270 and 370 having a thickness of 70 nm and made of n ⁺ -InGaAs are formed on the emitter layer. In the varactor, this n ⁺ -InGaAs layer is used as the cathode contact layer 270, and in the HBT, it is used as the emitter contact layer 370. The n ⁺ -InP layer at the top of the emitter layer is a layer for reducing the influence of conduction band discontinuity between InP of the emitter layer and InGaAs of the emitter contact layer.

  A multilayer structure in which Ti (titanium), Pt (platinum), and Au (gold) are deposited from below on the collector contact layer 330 of the HBT (hereinafter referred to as Ti / Pt / Au, and others) The same applies to the electrodes and the like), and a collector electrode 41 having a total thickness of 600 nm is formed. On the base layer 350, a base electrode 42 made of Ti / Pt / Au and having a total thickness of 200 nm is formed. An emitter electrode having a total thickness of 590 nm is formed on the emitter contact layer 38. The emitter electrode is composed of an emitter lower layer electrode 43 provided on the upper surface of the emitter contact layer, an emitter middle layer electrode 44 thereon, and an emitter upper layer electrode 45 thereon. The emitter lower layer electrode is WSi (tungsten silicide) having a thickness of 200 nm, and the emitter middle layer electrode has a total thickness of 190 nm and is made of Ti / Pt / Au. The emitter upper layer electrode has a total thickness of 200 nm and is made of Ti / Pt / Au. In this embodiment, it is assumed that the heights of the upper surfaces of the base electrode and the collector electrode are at the same position.

  The width of the base electrode is 0.5 μm, the width of the emitter electrode is 1.5 μm, and the base electrode and the emitter electrode are arranged with a gap of 0.25 μm. The collector electrode has a width of 4 μm, and the collector electrode and the base electrode are arranged with a gap of 1 μm.

  The collector electrode, base electrode, and emitter electrode are connected to the anode and cathode electrodes of the diode and the external circuit by wiring electrodes 541, 542, and 545, respectively.

An emitter base protection portion 306 is formed on the base layer so as to cover the side surface of the emitter layer, the upper surface of the base layer, the upper surface and side surfaces of the base electrode, and the side surface of the emitter electrode, excluding the wiring electrode 542. The emitter base protection part is composed of a first organic film such as polyimide or BCB. The height H _ORG1 of the upper surface of the emitter base protection portion may be equal to or less than the height of the emitter electrode. The height reference is the interface between the semiconductor substrate and the collector contact layer.

Although not shown, an inorganic film SiN _x having a thickness of 50 nm may be provided so as to directly cover the upper surface of the base layer between the base electrode and the emitter electrode from the side surface of the emitter middle layer electrode via the side surface of the emitter layer.

  In this way, by directly protecting the exposed portion of the semiconductor on the side surface of the emitter layer and the upper surface of the base layer with an organic film or an inorganic film, the reliability caused by the semiconductor material such as leakage current generated on the semiconductor surface Can be suppressed. Further, by adopting a structure in which an organic film is sandwiched between the base electrode and the emitter electrode, the insulation between the base electrode and the emitter electrode is improved, and stable operation can be expected.

Next, the diode on the lower layer part 22a of the hierarchical structure of the diode and the upper layer part 22b which is the substance will be described. A cathode layer 280 having a total thickness of 370 nm is formed on the cathode contact layer. The cathode layer includes n ⁺ -InP and n-InAlAs. An anode contact layer made of p ⁺ -InGaAs is formed on the cathode layer.

  An anode electrode made of Ti / Pt / Au and having a total thickness of 140 nm is formed on the anode contact layer. On the other hand, on the cathode contact layer, a cathode electrode made of Ti / Pt / Au and having a total thickness of 580 nm is formed. The anode electrode and the cathode electrode are positioned with a gap of 1.5 μm.

The anode / cathode protection unit 202 is made of SiN _x which is a first inorganic film, and is formed so as to cover the side surfaces of the anode electrode and the cathode electrode, the side surfaces of the anode contact layer and the cathode layer, and the upper surface of the cathode contact layer. Thus, by protecting the exposed portion of the semiconductor surface with the inorganic film, it is possible to prevent the reliability of the varactor diode from being lowered due to the semiconductor. The height in this embodiment the anode electrode H _AN and the cathode electrode H _CS is set to be the same, the height of the upper surface of the anode cathodic protection unit is the same as the height of the upper surface of the anode electrode H _AN and the cathode electrode.

  The anode electrode and the cathode electrode are connected to each electrode of the HBT or an external circuit by wiring electrodes 561 and 562, respectively. The width of the connection portion between the anode electrode and the cathode electrode of the wiring electrode is slightly reduced.

  The second organic film 111 is formed so as to cover from a part of the side surface of the emitter base protection part to the side surface of the collector layer and a part of the side surface of the anode cathode protection part of the diode part via the element isolation part and the collector electrode. ing.

FIG. 2 shows the positional relationship between the height of the upper surface of the anode base, the cathode electrode, the emitter electrode, the base electrode, the collector electrode, and the emitter base protection part formed from the second organic film 111 and the first organic film. The height _{H AN} of the upper surface of the anode electrode, the height _{H CS} of the upper surface of the cathode electrode, the height _{H EM} of the upper surface of the emitter electrode becomes _H AN _{= H} CS _{= H EM} identical. The height H _BA of the upper surface of the base electrode is the same as the height H _CL of the upper surface of the collector electrode, and H _CL = H _BA . The height H _ORG2 of the upper surface of the second organic film 111 is lower than the height H _ORG1 of the upper surface of the emitter base protection part 306, and H _ORG2 <H _ORG1 . In FIG. 2, the height H _ORG1 of the upper surface of the emitter base protection portion is lower than the height of the upper surface of the emitter electrode, so that H _ORG1 <H _EM , and H _BA <H _ORG2 <H _ORG1 <H _EM .

The inorganic film 112 passes through the upper surface of the second organic film 111 and the upper surface of the emitter base protection portion from the upper surface of the anode electrode and the cathode electrode, except for the positions where the wiring electrodes 541, 542, 545, 561, and 562 are formed. And is formed so as to cover the upper surface of the emitter electrode. The inorganic film 112 is made of SiN _x and has a film thickness of 140 nm. The entire element can be protected by the inorganic film 112. In particular, the moisture absorption of the organic film can be reduced by protecting the surface of the organic film made of BCB. Therefore, peeling of the organic film from the semiconductor or inorganic film or electrode interface due to moisture absorption or deterioration of the insulating property can be prevented.

  Note that the second inorganic film and the third inorganic film will be described later, and the inorganic film 112 is a fourth inorganic film.

  The emitter electrode wiring electrode 545 and the anode and cathode electrode wiring electrodes 561 and 562 are connected to the emitter electrode, the anode electrode, and the cathode electrode through contact holes formed from the side walls of the fourth inorganic film 112.

  The collector electrode wiring electrode 541 is connected to the collector electrode from above via a contact hole formed from the side walls of the fourth inorganic film 112 and the second organic film 111. Since the collector electrode and the base electrode have the same height, the contact hole of the collector electrode can be formed with a shallow depth. Since the contact hole of the collector electrode becomes shallow, it is possible to prevent disconnection of the electrode that occurs when the wiring electrode is formed through the contact hole of the collector electrode. Therefore, it is possible to improve the manufacturing stability.

  The base electrode wiring electrode 542 is connected to the fourth inorganic film 112 through a contact hole formed from the side wall of the first organic film 306. The contact hole of the base electrode is formed by etching the fourth inorganic film 112 and the first organic film 306 above the base electrode. In general, if the thickness of the film to be etched is thick, the etching time becomes long, so that etching proceeds not only in the height direction but also in the width direction, and a contact hole larger than the desired dimension is obtained. This is the effect of so-called side etching. In order to reduce the influence of this side etch, the first organic film 306 has a relatively thin film thickness in a range where the height of the upper surface of the first organic film 306 is higher than the upper surface of the base electrode and lower than the height of the upper surface of the emitter electrode. Yes. By adopting this configuration, it is possible to suppress the expansion of the contact hole in the width direction and form a contact hole with a smaller size. Accordingly, a base electrode having a very small size can be formed in advance.

  If a smaller base electrode can be formed in advance, the base electrode and the emitter electrode can be brought close to each other, and the capacitance of the junction between the p-type semiconductor of the base layer and the n-type semiconductor of the collector layer is also reduced. The band of the transistor defined by the time constant can be extended to the high frequency side.

  Note that if the height of the first organic film 306 above the base electrode is lower than the base electrode 41, the base organic film 306 is excessively etched between the base electrode and the emitter electrode when the contact hole is formed. There is a possibility that the insulation between the electrode and the emitter electrode is lowered and eventually short-circuited. For this reason, it is desirable that the height of the first organic film above the base electrode is appropriately set within a range in which expansion of the contact hole can be suppressed and insulation between the base electrode and the emitter electrode can be secured.

Since the height H _ORG1 of the upper surface of the emitter base protection part is higher than the height H _ORG2 of the upper surface of the second organic film and lower than the height H _EM of the emitter electrode (H _ORG2 <H _ORG1 <H _EM ). The upper surface of the second organic film, the upper surface of the base emitter protection portion, and the upper surface of the emitter electrode form a three-step staircase shape. In addition, since the height H _CL of the collector electrode and the height H _BA of the base electrode are the same, the step between the upper surface of the second organic film and the upper surface of the emitter base protection portion is close to the staircase. It can be seen that the steps of the shape are relatively small. When forming contact holes for wiring electrodes on the basis of this staircase shape with a relatively small step, the resist for forming the wiring electrode is formed on a flatter surface than when using a shape whose height changes sharply as a base. Since it can be applied, the resist film thickness distribution can be reduced. Further, the fourth inorganic film 112 can also be formed without being disconnected. Therefore, the contact hole of the wiring electrode for connecting the base electrode can be formed stably.

When the height H _ORG2 of the upper surface of the second organic film is the same as the height H _EM of the emitter electrode, the upper surface of the second organic film and the upper surface of the base emitter protection portion have a two-step staircase shape. Even in this case, the resist and the fourth inorganic film 112 when forming the contact hole of the wiring electrode can be formed without any step.

  The step shape formed by the upper surface of the second organic film on the collector electrode and the upper surface of the emitter base protection part is a shape obtained by etching back the second organic film 111 by etching the entire surface. Hereinafter, the entire etching of the second organic film will be described.

  FIG. 3 shows a configuration at the time of starting etching of the entire surface of the second organic film in the manufacturing process of the semiconductor integrated circuit. FIG. 4 shows a configuration when the entire surface etching is completed. The entire surface etching is performed until the first inorganic film 202 on the anode electrode is completely removed by etching, and the film removed by etching is indicated by a broken line.

On the varactor side, a first inorganic film 202 having a thickness of 280 nm, which forms an anode-cathode protection part on the anode electrode and the cathode electrode, is made of SiN _x / SiO _{2 having} a total thickness of 350 nm on the inorganic film 202. A second inorganic film 209 is provided. On the other hand, on the HBT side, a first organic film having the same height as the emitter electrode is provided above the base electrode, and a third inorganic film made of SiN _x / SiO ₂ is formed on the first organic film and the emitter electrode. A membrane 309 is provided. The film thickness of SiN _x of the second inorganic film 209 is 100 nm and the film thickness of SiO ₂ is 250 nm. The film thickness of SiN _x of the third inorganic film 309 is 100 nm and the film thickness of SiO ₂ is 100 nm. Yes. The BCB as the second organic film covers the entire surface of the HBT and the varactor on the inorganic film 209 on the anode electrode and the cathode electrode, on the first organic film above the collector electrode, the emitter electrode and the base electrode. The film thickness is 5 μm.

  Here, the heights of the anode electrode, the cathode electrode, and the emitter electrode can be regarded as the same, and the thickness of the second inorganic film 209 on the anode electrode and the cathode electrode is the same as that of the third inorganic film 309 on the emitter electrode. Since it is thicker than the thickness, the height of the third inorganic film 309 above the emitter electrode is lower than the height of the upper surface of the second inorganic film 209 above the anode electrode and the cathode electrode. Therefore, the second organic film on the emitter electrode is formed thicker than the organic films on the anode electrode and the cathode electrode. Since the height of the upper surface of the third inorganic film 309 above the base electrode is the same as that of the third inorganic film 309 above the emitter electrode, the thickness of the second organic film above the base electrode and the emitter electrode The thickness of the upper second organic film is the same. Since the upper surface of the collector electrode is at the lowest position, the thickness of the second organic film on the collector electrode is thicker than the organic films on the other electrodes. Accordingly, the second organic film on each electrode has an anode electrode and a cathode electrode, an emitter electrode and a base electrode, and finally a collector electrode in order from the thinner one.

Here, the etching rate during the entire surface etching differs depending on the material of the organic film or the inorganic film, and BCB used as the organic film is larger than SiO ₂ used for the second inorganic film and the third inorganic film. It has an etching rate, and the ratio of the etching rates is 2: 1: 2 for BCB · SiO ₂ · SiN _x . That is, it can be seen that SiO ₂ is a material having a lower etching rate than BCB.

FIG. 5 shows the transition of etching from the start to the end of the entire surface etching. The points to be compared are as follows: at the start of etching (t ₀ = 0), after t _1, after t _2, after t ₃ , and at the end when t _{4 has} elapsed, the film on each electrode has a total of five points. The heights shall be compared. Note that 0 ≦ t ₀ <t ₁ <t ₂ <t ₃ <t ₄ .

A second organic film 111 is on the second inorganic film 209 on the anode electrode and the cathode electrode before the start of the entire surface etching. A first organic film 306 is provided on the base electrode, a third inorganic film 309 is provided on the first organic film, and a second organic film 111 is provided on the third inorganic film 309. A second organic film is formed on the collector electrode and the emitter electrode. The heights of the organic films above the anode electrode, the cathode electrode, the collector electrode, the base electrode, and the emitter electrode at the start of the entire surface etching, that is, after the elapse of time t ₀ (t ₀ = 0), are respectively h _an (t ₀ ), h _Cl (t ₀ ), h _ba (t ₀ ), and h _em (t ₀ ) are indicated by broken lines in FIG.
h _an (t ₀ ) = h _cl (t ₀ ) = h _ba (t ₀ ) = h _em (t ₀ ).

Thereafter, the height of the upper surface of the second organic film at the start of etching is compared with each other as t ₀ = 0, and the height of the upper surface of the organic film on each electrode after the start of etching is within the same range. _{If 0} is set, it is not necessary to fix t ₀ = 0.

When the whole surface etching is started, the second organic film above the anode electrode, the cathode electrode, the emitter electrode, the base electrode, and the collector electrode is removed by etching with the lapse of time, and the thickness of the second organic film is reduced. The etching of the thinnest second organic film above the anode electrode and the cathode electrode is completed when time t _{1 has} elapsed from the start of the process.

When the time t _{1 has} elapsed, the heights of the films above the anode electrode, the cathode electrode, the collector electrode, the base electrode, and the emitter electrode are set to h _an (t ₁ ), h _cl (t ₁ ), h _ba (t _{1, respectively.} ), H _em (t ₁ ), as indicated by a solid line in FIG.
h _an (t ₁ ) = h _cl (t ₁ ) = h _ba (t ₁ ) = h _em (t ₁ )
It is.

After the etching of the organic film on the anode electrode and the cathode electrode is completed, the process shifts to etching of the second inorganic film 209. Then when the time from the start of the entire surface etching t ₂ elapsed, above the emitter electrode and the base electrode is completed all of the etching of the second organic layer. Since the second inorganic film contains SiO ₂ having an etching rate lower than that of BCB, the second organic film above the collector electrode, the base electrode, and the emitter electrode is etched at a faster rate than the second inorganic film. It will be.

When the time t _{2 has} elapsed, the height of the upper surface of the film on each electrode is defined as the height of the film above the anode electrode, the cathode electrode, the collector electrode, the base electrode, and the emitter electrode, respectively, h _an (t ₂ ), h _cl (t ₂ ), h _ba (t ₂ ), and h _em (t ₂ ) are indicated by a one-dot broken line at t ₂ in FIG.
h _an (t ₂ )> h _cl (t ₂ ),
h _cl (t ₂ ) = h _ba (t ₂ ) = h _em (t ₂ ).

When the etching of the second organic film above the base electrode and the emitter electrode is completed, the etching of the third inorganic film 309 above the base electrode and above the emitter electrode starts. At the beginning after a time t ₃ has elapsed etching, etching of the third inorganic film 309 above the upper and the emitter electrode of the base electrode is completed. Even when the etching of the third inorganic film is completed, the SiO ₂ contained in the second inorganic film 209 on the anode electrode and the cathode electrode is formed thicker in advance than the SiO ₂ contained in the third inorganic film. Therefore, the second inorganic film 209 is still etched on the anode electrode and the cathode electrode. On the other hand, only the second organic film is continuously etched on the collector electrode even when the second inorganic film or the third inorganic film is etched.

When the time t _{3 has} elapsed, the height of the upper surface of the film on each electrode is defined as the height of the film above the anode electrode, the cathode electrode, the collector electrode, the base electrode, and the emitter electrode, respectively, h _an (t ₃ ), The broken lines in FIG. 5 indicate h _cl (t ₃ ), h _ba (t ₃ ), and h _em (t ₃ ).
h _an (t ₃ )> h _ba (t ₃ )> h _cl (t ₃ )
h _ba (t ₃ ) = h _em (t ₃ ).

  When the etching of the third inorganic film 309 above the base electrode and the emitter electrode is completed, the third inorganic film 309 above the emitter electrode is all removed by etching, and the process proceeds to etching of the emitter electrode. Since the etching rate of the electrode material constituting the emitter electrode is remarkably smaller than that of the organic film or inorganic film, the decrease in the thickness of the emitter electrode is the amount of decrease in the thickness of the organic film or inorganic film on the other electrode. It is significantly smaller than that. Therefore, after that, even if the etching of the organic film or the inorganic film on the other electrode is continued, the etching of the emitter electrode does not proceed, and it can be considered that the height of the emitter electrode is constant.

Simultaneously with the etching of the emitter electrode, the etching shifts to the etching of the first organic film above the base electrode. At this time, the etching of the second inorganic film 209 is continued on the anode electrode and the cathode electrode, and after a while, the etching of the second inorganic film 209 is completed and the process shifts to the etching of the first inorganic film 202. Further, since only the second organic film made of BCB having a high etching rate is continuously etched on the collector electrode after the entire surface etching is started, the thickness of the film on the collector electrode to be removed by the etching is different. It becomes larger than the thickness of the film removed by etching on the electrode. Therefore, the height of the upper surface of the second organic film 111 on the collector electrode is the lowest. Then etching of the first inorganic film 202 located on the anode electrode and the cathode electrode when the time from the start of the entire surface etching and t ₄ elapses all completed. The total time of etching at this time as t _4, to end the blanket etching.

When the etching of the entire surface is completed, that is, when time t _{4 has} elapsed, the height of the upper surface of the film on each electrode is set to the height of the film above the anode electrode, the cathode electrode, the collector electrode, the base electrode, and the emitter electrode, respectively. _An solid line in FIG. 5 is shown as _an (t ₄ ), h _cl (t ₄ ), h _ba (t ₄ ), and h _em (t ₄ ).
h _an (t ₄ )> h _em (t ₄ )> h _ba (t ₄ )> h _cl (t ₄ )
It is.

As shown by the lines h _an (t ₄ ), h _cl (t ₄ ), h _ba (t ₄ ), and h _em (t ₄ ) in FIG. 5, the upper surface of the emitter electrode and the upper surface of the organic film on the base electrode The height is lower in order from the upper surface of the organic film on the collector electrode. As described above, since the third inorganic film 309 having a low etching rate is sandwiched between the first organic film 306 and the second organic film 111 above the emitter electrode, the first etching film having a high etching rate is used. Etching proceeds rapidly above the collector electrode consisting of only two organic films, and the height of the second organic film above the collector electrode is the upper surface of the first organic film of the base emitter protection portion above the base layer. As a result, the height of the upper surface of the emitter electrode, the upper surface of the first organic film above the base electrode, and the upper surface of the second organic film above the collector contact electrode are sequentially reduced. Can be obtained.

  In this example, the entire surface etching was finished when the etching of the inorganic film 202 on the anode and cathode electrodes was completed. Since the entire surface etching is finished before the first inorganic film 202 protecting the side surfaces of the cathode layer and the anode contact layer is etched, the side surfaces of the cathode layer and the anode contact layer where the semiconductor is exposed are directly etched. Can be prevented. Therefore, a highly reliable diode can be obtained without damaging the diode by etching.

  Further, in the case where the distribution of the etching rate of the organic film, the film thickness distribution, and the like are small and the entire surface etching can be accurately controlled, a configuration without the third inorganic film 309 may be used. When the distribution of the etching rate value or the film thickness distribution of the organic film is large, the organic film covering the emitter electrode and the base electrode is over-etched to prevent the occurrence of a short circuit between the emitter and base. An inorganic film is formed. By forming the third inorganic film, the thickness of the first organic film covering the base electrode at the end of the entire surface etching is increased, and the insulation between the base electrode and the emitter electrode can be further improved. Note that the first inorganic film 202 may include a material having a lower etching rate than the first organic film and the second organic film, and the second inorganic film may be omitted.

  The entire surface etching may be completed in a state where the first inorganic film 202 or the second inorganic film 209 on the anode electrode and the cathode electrode of the diode are not completely removed by etching, and any of them remains. At this time, the etching is stopped when the emitter electrode is exposed, and the height of the upper surface of the first inorganic film 202 or the second inorganic film covering the cathode electrode is confirmed with reference to the height of the emitter electrode. In any case, it is possible to ensure the reliability of the diode, and on the transistor side, the height of the second organic film above the contact electrode is lower than the height of the first organic film above the base electrode. The following staircase shape can be obtained. In this case, the contact hole may be formed by opening the remaining first inorganic film 202 and second inorganic film 209 together with the fourth inorganic film 112.

(Second embodiment)
FIG. 6 shows a second embodiment. As shown in FIG. 6, a third inorganic film 309 may be provided on the side surface of the collector layer and the side surface of the emitter base protection portion of the transistor.

  FIG. 7 shows a configuration at the time of starting the entire surface etching in the configuration of FIG. At the start of the entire surface etching, a third inorganic film 309 on the emitter electrode and the emitter base protection part is formed to extend so as to cover the side surface of the emitter base protection part and the side surface of the collector layer. As shown in FIG. 8, after the entire surface etching is completed, the third inorganic film 309 on the upper surface of the emitter electrode and the emitter base protection portion is all removed, and the side surface of the collector layer of the transistor and the side surface of the emitter base protection portion 3 of the inorganic film 309 remains.

  By adopting a configuration in which the side surface of the emitter base protection portion is covered with the inorganic film 309 as shown in FIG. 6, moisture absorption of the first organic film 306 during the manufacture of the semiconductor integrated circuit can be prevented. Further, by covering the side surface of the collector layer of the transistor with an inorganic film, the surface of the collector layer exposed by the semiconductor can be protected. As a result, peeling of the organic film from the semiconductor and deterioration of the insulating property can be prevented, and damage to the semiconductor can be reduced, whereby a transistor with higher reliability can be obtained.

(Third embodiment)
FIG. 9 shows a third embodiment. In FIG. 9, the second inorganic film 209 on the diode side is located at the same height as the second organic film on the side surface of the anode-cathode protection portion, and the side surface of the lower layer portion 22 a of the varactor hierarchical structure and the element isolation portion on the diode side It is formed so as to cover the upper surface of. On the other hand, on the HBT side, a configuration is shown in which a third inorganic film 309 is formed so as to cover the side surface of the collector layer of the transistor, the side surface of the emitter base protection portion 306, and the upper surface of the collector contact layer. FIG. 10 shows the state at the start of the entire surface etching for obtaining this configuration, and FIG. 11 shows the state at the end of the entire surface etching.

By adopting the configuration of FIG. 9, the element isolation part on the varactor side is covered with the second inorganic film, and the surface of the collector contact layer is covered with the third inorganic film, thereby further improving the reliability of the varactor and the HBT. Can be improved. Even when the entire surface etching is completed, the thickness of the second inorganic film on the surface of the element isolation part on the varactor side is the same as the thickness of the second inorganic film on the anode electrode at the start of the entire surface etching. Similarly, the thickness of the third inorganic film on the upper surface of the collector contact layer on the element isolation part side on the HBT side is the same as the thickness of the third inorganic film on the emitter base protection part at the start of the entire surface etching. is there. Moreover, than the SiO ₂ thickness comprised third inorganic film on the upper surface of the collector contact layer of the element isolation portion, than the thickness of the SiO ₂ contained in the second inorganic film on the surface of the element isolation portion varactor side It is also thick. Therefore, the second inorganic film on the upper surface of the element isolation part on the varactor side before and after the entire surface etching and the third inorganic film on the upper surface of the collector contact layer on the element isolation part side of the HBT are protected and etched by the second organic film. The second inorganic film on the anode electrode and the third inorganic film on the emitter base protection portion at the start of the entire surface etching have the same material structure.

(Fourth embodiment)
FIG. 12 shows a fourth embodiment. In FIG. 12, the second inorganic film 209 on the varactor side covers the side surface of the lower layer part of the varactor and the upper surface of the element isolation part on the varactor side from the same height as the second organic film on the side surface of the anode cathode protection part. Formed as follows. On the other hand, on the HBT side, the third inorganic film 309 is formed so as to cover the side surface of the collector layer of the HBT, the side surface of the emitter base protection portion 306, and the upper surface of the collector contact layer to the element isolation portion on the transistor side. Indicates. FIG. 13 shows the state at the start of the entire surface etching for obtaining this configuration, and FIG. 14 shows the state at the end of the entire surface etching.

With the configuration of FIG. 12, the reliability of the HBT can be further improved by covering the surface of the element isolation portion where the semiconductor substrate is exposed with the second inorganic film and the third inorganic film. Even when the entire surface etching is completed, the thickness of the second inorganic film on the surface of the element isolation part on the varactor side is the same as the thickness of the second inorganic film on the anode electrode at the start of the entire surface etching. Included in the second inorganic film on the surface of the element isolation part on the varactor side from the thickness of SiO ₂ contained in the third inorganic film on the surface of the element isolation part on the HBT side, as in the case of starting the entire surface etching and has a thicker configuration than the thickness of the SiO ₂ to be. Therefore, the second inorganic film on the upper surface of the element isolation part on the varactor side and the third inorganic film on the upper surface of the element isolation part on the transistor side are protected by the second organic film before and after the etching, so that they are etched. Instead, the second inorganic film on the anode electrode and the third inorganic film on the emitter base protection portion at the start of the entire surface etching have the same material structure.

  In any of the embodiments of FIGS. 1, 6, 9, and 12, the second inorganic material on the anode electrode is shown at the end of the entire surface etching, as indicated by the broken line in FIGS. 5, 9, 12, and 15. After the film, the first inorganic film, a part of the first organic film on the base electrode, and the third inorganic film on the base electrode and the emitter electrode are all removed by etching, the second organic film is removed. A step shape is formed by the film and the first organic film.

In this manner, the second inorganic film containing SiO ₂ , which is a material having a lower etching rate than BCB, is provided on the anode electrode and the cathode electrode at the start of the entire surface etching, and the third inorganic film is formed on the base electrode. By performing the entire surface etching after being provided on the organic film, an ideal step shape can be formed by the organic film on the base electrode and the organic film on the collector electrode without impairing the reliability of the varactor. As a result, it is possible to stably form the contact hole of the wiring electrode that connects the minute base electrode.

  In addition, the organic film included in the inorganic film 209 and the inorganic film 309 is more optimized so that the height of the second organic film above the contact electrode of the transistor and the height of the first organic film above the base electrode are optimized. Needless to say, the ratio between the film thickness of the material having a low etching rate and the etching rate can be adjusted as appropriate.

  Further, as another effect that the top surface of the emitter electrode, the top surface of the organic film above the base electrode, and the top surface of the organic film above the collector contact electrode have a stepped shape, the wiring electrode can be formed smoothly. There is also an effect.

  FIG. 15 is a cross-sectional view and a plan view of the HBT. 1, 6, 9, and 12 are sectional views taken along the line XX ′ described in the plan view of FIG. 15, whereas the sectional view of FIG. 15 is perpendicular to XX ′. It is sectional drawing of YY 'and a height direction.

The wiring electrode 545 for connecting the emitter electrode passes through the upper surface of the organic film covering the base electrode and the upper surface of the organic film above the collector contact electrode, and is connected to the lower wiring electrode via a contact hole 486 provided in the second organic film. 86. The wiring electrode 545 that connects the emitter electrode by using a smooth stepped shape composed of the upper surface of the base electrode and the first organic film covering the base electrode and the second organic film covering the collector electrode can be used as an external circuit. Or it becomes possible to connect to each electrode of a diode. The lower layer wiring electrode 81 is connected to the collector electrode wiring electrode 541 via the contact hole 481, and the lower layer wiring electrode 82 is connected to the base electrode wiring electrode 542 via the contact hole 482. The lower wiring electrode is formed under the contact holes 481, 482, 486, and is formed on the inorganic film 409 made of SiN _x / SiO ₂ on the semiconductor substrate 21. The inorganic film 409 may be formed by extending the second inorganic film or the third inorganic film to the contact holes 481, 482, and 486, and a lower wiring electrode may be formed thereon. The film thickness of the lower wiring electrode is 400 nm, and is made of Ti / Pt / Au as an example.

  Note that by making the height of the upper surface of the lower wiring electrode the same as the height of the upper surface of the collector electrode, the depth of the contact hole 486 of the lower wiring electrode can be reduced, and disconnection of the wiring electrode can be prevented. it can.

  Further, the fourth inorganic film can be formed more smoothly by making the heights of the anode electrode and the emitter electrode or the cathode electrode and the emitter electrode equal. Therefore, the wiring electrode 562 connected to the anode electrode or the wiring electrode 561 connected to the cathode electrode can be formed without any step.

  Further, since the heights of the collector electrode and the base electrode are made equal, the step difference between the upper surfaces of the second organic film covering the collector electrode and the first organic film covering the base electrode can be made smaller. The wiring electrode 545 can be formed smoothly.

  Further, as another effect of making the heights of the collector electrode and the base electrode equal, the depth of the contact hole of the collector electrode can be reduced, and the wiring electrode of the collector electrode can be formed without disconnection.

A similar effect can be obtained even in a configuration in which an anode layer made of a p-type semiconductor having conductivity lower than p ⁺ is provided between the cathode layer and the anode contact layer of the varactor.

  In this embodiment, the diode is a varactor diode and the transistor is an HBT. However, the present invention can be applied to a diode other than a varactor diode and a transistor other than an HBT.

(Production method)
Next, a method for manufacturing the semiconductor integrated circuit having the above structure will be described.

  First, as shown in FIG. 16, a collector contact layer 130, a collector layer 140, a base layer 150, an emitter layer 160, and an emitter contact layer 170 necessary for the HBT are epitaxially grown on the semiconductor substrate 21 in this order. A cathode layer 180 and an anode contact layer 190 necessary for forming the diode are epitaxially grown thereon, and an anode electrode 62 is formed by vapor deposition at the anode formation position of the uppermost layer of the diode (step 1).

The collector contact layer 130 is grown on the semiconductor substrate 21 made of InP so as to have a total thickness of 270 nm, and the collector contact layer 130 includes n ⁺ -InP and n ⁺ -InGaAs 133 (indium gallium arsenide). Crystal growth.

A collector layer 140 having a total thickness of 350 nm is crystal-grown on the collector contact layer, and the collector layer is crystal-grown so as to include n-InP, i-InP, i-InGaAs, and n-InGaAs. Further, the base layer 150 is crystal-grown on the collector layer, and the base layer is crystal-grown so as to be made of p ⁺ -InGaAs.

An emitter layer 160 having a total thickness of 70 nm is crystal-grown on the base layer. The emitter layer is crystal-grown so as to contain n-InGaAs and n-InP. Furthermore, a layer 170 serving as an emitter contact and a cathode contact layer containing n ⁺ -InGaAs is grown on the emitter layer. The cathode layer 180 is crystal-grown so as to include n ⁺ -InP and n-InAlAs. An anode contact layer made of p ⁺ InGaAs is crystal-grown on the cathode layer.

  Then, as shown in FIG. 17, the portions other than the cathode electrode position are covered with the resist 101, and the anode contact 190 layer and the cathode layer 180 which are not covered with the resist are removed by etching to form the anode contact layer 290 and the cathode layer 280. (Step 2). As shown in FIG. 18, the cathode electrode 61 is deposited on the exposed upper surface of the cathode contact and emitter contact layer 170, and unnecessary resist 101 is removed (step 3).

Subsequently, as shown in FIG. 19, the entire surface is covered with a first inorganic film 102 made of SiN _x having a thickness of 280 nm. (Step 4) Further, as shown in FIG. 20, the anode 103 and the cathode electrode of the diode are covered with a resist 103, and the portion of the first inorganic film not covered with the resist 103 is removed by dry etching, The surface of the contact and emitter contact layer 170 is exposed. The resist 103 that is no longer needed is removed, and the anode-cathode protection part 202 made of the inorganic film 102 covered with the resist 103 is formed (step 5).

Subsequently, as shown in FIG. 21, the entire surface is covered with the WSi film 104, and the emitter middle layer electrode 44 is formed by evaporation at the emitter formation position in the surface of the film (step 6), and further dry etching is performed, thereby FIG. As described above, the portion of the WSi film 104 not covered with the emitter middle layer electrode 44 is removed to form the emitter lower layer electrode 43 (step 7).

  Subsequently, as shown in FIG. 23, wet etching is performed on the emitter contact layer 170 and the emitter layer 160 in a portion not covered with the first inorganic film and the emitter lower layer electrode, using the first inorganic film and the emitter lower layer electrode 43 as a mask. The emitter layer 360 and the emitter contact layer 370 of the transistor are formed (step 8). Further, as shown in FIG. 24, a base electrode 42 is deposited on the exposed surface of the base layer. At the same time, an emitter upper layer electrode 45 is deposited on the emitter middle layer electrode 44 (step 9).

  Subsequently, as shown in FIG. 25, 530 nm-thick BCB to be the first organic film 106 protecting the emitter layer and the emitter contact layer is applied (step 10). Thereafter, as shown in FIG. 26, the region including the upper surface of the emitter electrode and a part of the first organic film above the base electrode is covered with a resist, and the first organic film 111 not covered with the resist by dry etching is covered. Then, the base layer 150 and the contact layer 140 are removed. Thereafter, the resist that is no longer needed is removed, and the emitter base protection portion 306 made of the first organic film 106 covered with the resist, the collector layer 340 of the transistor, and the base layer 350 are formed (step 11).

  Subsequently, as shown in FIG. 27, the collector electrode 41 is formed by vapor deposition on the exposed upper surface of the collector contact layer 140 (step 12).

  Subsequently, an element isolation portion is formed as shown in FIG. A resist 108 is formed so as to cover the collector electrode and the emitter base protection part, and further a resist 108 is formed so as to cover the anode cathode protection part. By removing the collector contact layer 130 in the region not covered with the resist between the anode / cathode protective portion and the collector electrode by wet etching, element isolation between the collector contact layer of the lower layer of the diode and the collector contact layer 230 of the transistor is performed. Is made. Thereafter, the resist that is no longer needed is removed, and the upper surface of the region 70 of the semiconductor substrate 21 is used as an element isolation portion (step 13). The varactor and the HBT are separated from each other at an element separation position 71 in the element separation unit 70.

Subsequently, as shown in FIG. 29, the entire surface is covered with an inorganic film 109 (a silicon nitride film SiN _x and a silicon oxide film SiO ₂ ) to be a second inorganic film by chemical vapor deposition (step 14). Thereafter, as shown in FIG. 30, from the entire upper surface of the anode cathode protection portion including the anode electrode and the cathode electrode to the region from the side surface of the anode cathode protection portion and the side surface of the lower layer portion of the diode to the element isolation position of the element isolation portion. A resist 110 is formed so as to cover (step 15).

  Subsequently, as shown in FIG. 31, the second inorganic film 109 in a region not covered with the resist is etched by dry etching (step 16). As shown in FIG. 32, the second inorganic film 109 in which the region not covered with the resist remains after etching is used as a third inorganic film 309. In this way, the second inorganic film 209 in the region covered with the resist becomes thicker than the third inorganic film 309 (step 17).

  Next, as shown in FIG. 33, 5 μm-thick BCB to be the second organic film 111 is applied to the entire surface (step 18).

Subsequently, the entire surface of the second organic film 111 is etched from the BCB applied to the entire surface by an etch back method. Focusing on the anode / cathode protection part of the diode, the second organic film 111, the second inorganic film 209, and the first inorganic film 202 are etched in this order. Only the second organic film 111 is removed by etching above the element isolation portion and the collector electrode, and the second organic film 111, the third inorganic film 309, and the first organic film 306 are sequentially removed above the base electrode. Etched. Above the emitter electrode 45, the second organic film and the third inorganic film are etched in this order. In the first organic layer and the BCB are used in the second organic layer, the ratio of the second inorganic layer and the third etch rate of which SiO2 and SiN _x which used an inorganic film BCB · SiO2 · SiN _x 2: 1: 2.

After the time t _{1 has} elapsed from the start of etching of the entire surface, the etching of the second organic film 111 above the anode electrode is completed as shown in FIG. 34, and the second inorganic film 209 above the anode electrode is completed. (Step 19a). When the second inorganic film above the anode electrode is etched, the second organic film is continuously etched above the element isolation portion and the collector electrode. Since the etching rate of SiO ₂ used in the second inorganic film is smaller than the etching rate of BCB used in the second organic film, the etching proceeds faster above the collector electrode than above the anode electrode. It becomes.

Subsequently, the process shifts to etching of the inorganic film 209 on the anode electrode and the cathode electrode, and after a while, the etching of the organic film 111 above the emitter electrode and the base electrode is completed as shown in FIG. 35 (step 19b). This time is defined as a time t ₂ after the start of the entire surface etching. Thereafter, etching of the third inorganic film 309 on the upper surfaces of the emitter electrode and the emitter base protection portion is started above the emitter electrode and the base electrode. Since the third inorganic film is thinner than the second inorganic film, before the etching of the second inorganic film above the anode electrode and the cathode electrode is completed, the emitter electrode and the emitter base protection part The etching of the third inorganic film 309 on the upper surface of the substrate is completed. Note that the second organic film 111 is continuously etched above the element isolation portion and the collector electrode.

Subsequently, after the elapse of t ₃ hours from the start of the entire surface etching, the etching of the third inorganic film 309 on the upper surfaces of the emitter electrode and the emitter base protection portion is completed as shown in FIG. 36 (step 19c). Thereafter, the etching of the first organic film starts above the base electrode, and the etching of the electrode material of the emitter electrode being protected starts at the emitter electrode. Since the etching rate of the electrode material is significantly smaller than that of the organic film or inorganic film, the thickness of the emitter electrode removed by etching may be negligible compared to the inorganic film or organic film. Etching may not proceed.

Etching of the first organic film above the base electrode is started, and after a while, etching of the second inorganic film is completed above the anode electrode and the cathode electrode, and the process proceeds to etching of the first inorganic film 202. Complete etching of the first inorganic film of all, an anode electrode of the varactor diode, when the upper surface of the cathode electrode has time t ₄ has elapsed from the start of the etching exposed from the second organic film to terminate the entire surface etching (step 19d ). As shown in FIG. 37, the height of the upper surface of the first organic film on the base electrode when the entire surface etching is completed is lower than the height of the upper surface of the emitter electrode. Further, the height of the upper surface of the second organic film above the collector electrode is at the deepest position because only the second organic film is continuously etched, and the height of the upper surface of the first organic film on the base electrode is It becomes lower than the height. That is, the height decreases in the order of the upper surface of the first organic film on the emitter electrode, the anode electrode and the cathode electrode, the base electrode, and the upper surface of the second organic film above the collector electrode. A staircase shape consisting of the upper surface and the upper surface of the organic film above the base electrode can be obtained. As described above, the step 19 of the entire surface etching includes the steps 19a, 19b, 19c and 19d in this order.

Subsequently, as shown in FIG. 38, SiN _{x serving} as a fourth inorganic film is deposited on the entire surface with a thickness of 140 nm (step 20).

  Subsequently, as shown in FIG. 39, in order to form contact holes for connecting the anode electrode, the cathode electrode, the collector electrode, the base electrode, and the emitter electrode to the wiring, portions other than the positions where the contact holes are formed are covered with a resist. The fourth inorganic film is removed by etching above the anode, cathode, and emitter electrodes to form an anode contact hole, a cathode contact hole, and an emitter contact hole. Over the base electrode, the fourth inorganic film and the first organic film not covered with the resist are sequentially removed by etching to form a base contact hole. On the collector electrode, the fourth inorganic film, the second inorganic film, and the third inorganic film not covered with the resist are sequentially removed by etching to form a collector contact hole (step 21).

  Subsequently, as shown in FIG. 40, in order to fabricate the wiring electrode, the regions to be the anode electrode contact hole, the cathode electrode contact hole, the emitter electrode contact hole, the base electrode contact hole, and the collector electrode contact hole are formed with a resist. After covering and vapor-depositing Ti / Pt / Au with a total thickness of 1.5 μm on the entire surface, Au on the remaining resist is removed by lift-off, thereby forming a wiring electrode (step 22). Thus, the semiconductor integrated circuit having the configuration shown in FIG. 12 is completed.

  If the resist formation in step 15 and the etching in step 16 are repeated before the formation of the second organic film in step 18, the second inorganic film is provided only on the anode / cathode protection portion, and the third inorganic film is formed as the emitter. It can be set as the structure provided only on the base protection part. Even in this case, when the entire surface etching in step 22 is completed, the organic film on the collector electrode and the first organic film on the base electrode are stepped, and the semiconductor integrated circuit having the configuration of FIG. 1 can be obtained. .

  Further, if the resist formation in step 15 and the etching in step 16 are repeated before the second organic film formation in step 18, the second inorganic film is formed so as to include the anode cathode protection portion, and the third organic film is formed. An inorganic film may be provided so as to cover only the surface of the emitter base protection portion and the side surface of the collector layer. Even in this case, when the entire surface etching in step 22 is completed, the organic film on the collector electrode and the first organic film on the base electrode are stepped, and a semiconductor integrated circuit having the configuration of FIG. 6 can be obtained. .

  If the resist formation in step 15 and the etching in step 16 are repeated before the second organic film is formed in step 18, the entire HBT from the top of the anode electrode to the element isolation part on the HBT side is formed on the second inorganic film. The third inorganic film may be provided so as to cover the surface of the emitter base protection portion, the side surface of the collector layer, the surface of the collector electrode, and the upper surface of the collector contact layer. Even in this case, when the etching of the entire surface of step 19d is completed, the organic film on the collector electrode and the first organic film on the base electrode have a stepped shape, and a semiconductor integrated circuit having the configuration of FIG. 9 can be obtained. .

  When the in-plane distribution of the etching rate and film thickness of the materials contained in the first organic film and the second organic film, or the second inorganic film and the third inorganic film is controlled with high accuracy, Only the second inorganic film may be formed to start the entire surface etching. At this time, all the third inorganic film above the base electrode may be removed by etching in step 16. When the third inorganic film is not formed, instead of the second inorganic film, the first inorganic film includes a material having an etching rate higher than that of the first organic film and the second organic film. Reliability may be ensured. In this case, the second inorganic film need not be formed.

  Further, between step 14 and step 15, lower wiring electrodes 81, 82, 86 are formed on the inorganic film 109 on the semiconductor substrate, and at step 22, contact holes are formed on the lower wiring electrodes 81, 82, 86. If formed and the wiring electrode on the fourth inorganic film is connected to the lower wiring electrode in step 23, the configuration shown in FIG. 15 can be obtained.

  FIG. 41 shows a flowchart of the method for manufacturing the semiconductor integrated circuit described above.

  20 ... Varactor diode, 21 ... Semiconductor substrate, 22 ... Hierarchical structure of varactor, 30 ... HBT, 31 ... Hierarchical structure of HBT, 41 ... Collector electrode, 42 ... Collector Electrode, 43 ... emitter lower layer electrode, 44 ... emitter middle layer electrode, 45 ... emitter upper layer electrode, 61 ... cathode electrode, 62 ... anode electrode, 70 ... element isolation part, 71 Element isolation position 111 ... first organic film 112 ... fourth inorganic film 202 ... first inorganic film 209 ... second inorganic film 230, 330 .. Collector contact layer, 240, 340... Collector layer, 250, 350... Base layer, 260, 360... Emitter layer, 270, 370... Cathode contact / emitter contact layer, 280. Cathode layer, 290 ... anode contact layer, 306 ... first organic film, 309 ... third inorganic film, 541 ... collector electrode wiring, 542 ... base electrode Wiring electrode, 545... Emitter wiring electrode, 561... Cathode electrode wiring electrode, 562.

Claims (11)

A semiconductor substrate (21);
A diode (20) comprising a first hierarchical structure (22) on the semiconductor substrate;
A transistor (30) including a second hierarchical structure on said semiconductor substrate (31), a semiconductor integrated circuit having,
The first hierarchical structure (22) has a cathode layer (280) and an anode contact layer (290) on the cathode layer;
The second hierarchical structure includes a collector contact layer (330), a collector layer (340) over the collector contact layer, a base layer (350) over the collector layer, and an emitter layer (360) over the base layer. And an emitter contact layer (370) on the emitter layer,
In a semiconductor integrated circuit having an emitter electrode (46) on the emitter contact layer, a base electrode (42) on the base layer, and a collector electrode (41) on the collector contact layer,
A first inorganic film (202) covering side surfaces of the cathode layer and the anode contact layer;
A first organic film (306) covering a side surface of the emitter layer and the base electrode, and further covering between the base electrode and the emitter electrode;
Has, a second organic layer (111) covering the collector electrode,
The height of the upper surface of the anode contact layer is higher than the height of the upper surface of the emitter contact layer,
The height of the upper surface of the first organic film is lower than the height of the upper surface of the first inorganic film, and is not more than the height of the upper surface of the emitter electrode,
The semiconductor integrated circuit further comprising a wiring electrode (542) connected to the base electrode through a contact hole formed in the first organic film. 2. The semiconductor integrated circuit according to claim 1 , wherein the height of the upper surface of the second organic film is lower than the height of the upper surface of the first organic film. The semiconductor integrated circuit according to claim 1 or claim 2 the height of the top surface of the collector electrode is characterized in that equal to the height of the top surface of the base electrode. Having an anode electrode on the anode contact layer;
4. The semiconductor integrated circuit according to claim 1 , wherein the height of the upper surface of the anode electrode is equal to the height of the upper surface of the emitter electrode. The first hierarchical structure further includes a cathode contact layer under the cathode layer,
Having a cathode electrode on the cathode contact layer;
The semiconductor integrated circuit according to claim 1, wherein the cathode electrode and the emitter electrode have the same height. The semiconductor integrated circuit as claimed in any one of claims 5 layer structure beneath the cathode layer, characterized in that the same as the second hierarchical structure of the first hierarchy. 7. The semiconductor integrated circuit according to claim 1, further comprising a fourth inorganic film formed so as to cover an upper surface of the first organic film and an upper surface of the second organic film. The semiconductor integrated circuit according to any one of claims 1 to 7, characterized by further comprising a third inorganic layer (309) covering the side surfaces and the collector layer of the first organic layer . An element isolation part (70) that is an area between the first hierarchical structure and the second hierarchical structure and includes an element isolation position (71);
A second inorganic film (209) covering a side surface of the layer below the cathode layer and a region of the element isolation portion on the diode side in the first hierarchical structure;
The third inorganic film further covers from the surface of the collector electrode to the element isolation region on the transistor side,
The second inorganic film and the third inorganic film include a material having a lower etching rate than the first organic film and the second organic film,
The thickness of the material having an etching rate lower than that of the first organic film and the second organic film included in the second inorganic film is the first organic film included in the third inorganic film and the semiconductor integrated circuit of 請 Motomeko 8, wherein greater than the thickness of the low etching rate material than the second organic layer. A collector contact layer (130), a collector layer (140), a base layer (150), an emitter layer (160), an emitter contact layer (170) included in a transistor, and a cathode layer (180) included in a diode on a semiconductor substrate. And an anode contact layer (190) are epitaxially grown,
The cathode layer (280) and anode contact layer (290) of the diode, and the collector contact layer (330), collector layer (340), base layer (350), emitter layer (360), emitter contact layer (370) of the transistor. ) By etching,
An anode electrode, a collector electrode, a base electrode, method of manufacturing a semi-conductor integrated circuit forming the emitter electrode,
Forming a first inorganic film so as to cover side surfaces of the cathode layer and the anode contact layer (steps 7 and 8);
Forming a first organic film so as to cover the side surface of the emitter layer and the base electrode, and further cover between the base electrode and the emitter electrode (steps 10 and 11);
Forming a second inorganic film so as to cover the first inorganic film (step 14);
Forming a second organic film so as to cover the entire surface from the second inorganic film to the first organic film (step 18);
The second inorganic film includes a material having an etching rate lower than that of the first organic film and the second organic film,
Starting the entire etching of the second organic film;
The entire surface is etched until the height of the first organic film is higher than that of the base electrode and lower than the height of the emitter electrode (step 19).
Forming a contact hole in the first organic film (step 21);
Method of manufacturing a semi-conductor integrated circuit according to claim via said contact hole to form a wiring electrode connected to the base electrode that (step 22). After forming the second inorganic film (step 14),
Forming a third inorganic film so as to cover the upper surface of the first organic film (steps 15, 16, and 17);
The third inorganic film includes a material having an etching rate lower than that of the first organic film and the second organic film, and the first organic film and the second organic film included in the second inorganic film. The material having a lower etching rate than the organic film is thicker than the material having a lower etching rate than the first organic film and the second organic film included in the third inorganic film, 11. The method of manufacturing a semiconductor integrated circuit according to claim 10, wherein the entire etching of the second organic film is started.

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