JPS5987851A - Semiconductor integrated circuit and its manufacture - Google Patents

Abstract

PURPOSE:To improve the high-frequency characteristics of both a vertical type NPN transistor and a vertical type PNP transistor while increasing their speed and density by forming the integral structure of the vertical NPN transistor and the vertical type PNP transistor. CONSTITUTION:A nitride film 26, a foundation oxide film 25 and an N type epitaxial layer are etched while using a resist film 27 as a mask. The nitride film 26 is patterned again, and an oxide film 29 is formed between a base and a collector-contact in the vertical type NPN transistor (Tr) and an oxide film 29 around an emitter in the vertical type PNP Tr. Poly Si 32 is formed to the whole surface, a nitride film 33 is formed on the poly Si, and the nitride film 33 is patterned and the poly Si 32 and the N type epitaxial layer 24 are etched through a photolithography method. High-concentration N<+> regions 35a-35c are formed while using the resist film as a mask. The regions 35a, 35b each form an emitter and the collector-contact in the vertical type NPN Tr, and the region 35c forms a base-contact in the vertical type PNP Tr.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a semiconductor integrated circuit that achieves high speed and high density using an insulation isolation method and a method for manufacturing the same. The integrated structure of IN) run lister (hereinafter referred to as vertical NPNTr) and vertical PNP) run lister (hereinafter referred to as vertical PNPTr) can be achieved in a very simple manner at four speeds without deteriorating the characteristics of vertical NPNTt. Dense vertical PNP,
This makes it possible to manufacture 'I'r.

Conventional Structures and Their Problems In recent years, semiconductor integrated circuits have been moving in the direction of higher speeds and higher densities, and research on semiconductor integrated circuits using the insulation isolation method has been actively conducted.

The applicant has already developed a vertical NPN using the conventional insulation isolation method.
We improved the Tr and proposed a vertical NPNTr with excellent structure, characteristics, and process, and further developed the vertical NPNTr.
We have also proposed an integrated structure of an NTr and a horizontal PNPTr. The integrated structure of the vertical NPNTr and horizontal PNPTr is shown in FIG.

In FIG. 1, 1 is, for example, a P-type semiconductor substrate, and 2 is an n-type semiconductor substrate.
+Buried layer 3 is a heavily doped P region and serves as a channel Φ stopper for canceling out the n-type inversion layer generated when forming the element isolation oxide film. 4 ii 'n type epitaxial layer,
5 is an element isolation oxide film.

High-volume separation is now complete. Below, vertical NPNT
r will be explained first. Note that regions formed in the same process are indicated by the same color, and horizontal PNPTrs are all indicated by ''. In the vertical NPNTr, numeral 6 forms an oxide film separating the base and collector contact (base-collector isolation oxide film), 7 forms a collector wall, and 8 forms a low concentration p-region active base.

9 is polySt for drawing out the A6 electrode, 10 is an oxide film separating the emitter and base contact (emitter-base isolation oxide film), and 11a.

11b, the high concentration n+ region 11a forms an emitter, and 11b forms a collector contact. 12 is high concentration p
+ area forms an inert base area, emitter
The lower part of the base isolation oxide film is deep, and the base contact part is shallow and continuous. 13 is an Al electrode wiring.

The features of this vertical NPNTt are the emitter-base junction,
Since the sides of the collector-base junction and the collector region are all covered with an oxide film 1, the parasitic capacitance is as small as possible. By forming the base in a self-aligned manner, the base resistance is reduced. Therefore, it is possible to improve the high frequency characteristics and achieve higher speed and higher density.

Next, the horizontal PNPTr shown in FIG. 1 will be explained. 7′
The base resistance is reduced in the total region formed in the same process as the collector wall 7.

8'a, s'b are low concentration p-region active bases)8
The p'' region 9', which becomes part of the emitter and collector of the horizontal PNPTr, is formed in the same process as the polySt 9, and like the vertical NPN ugly Tr, the polySt for leading out the l electrode is formed in the same process. 10' is a horizontal PNPT formed in the same process as the emitter-base separation oxide film 10 of the vertical NPNTr.
oxide film separating the emitter and collector of r, 11'
is a horizontal NPN formed in the same process as the emitter 11a1 collector contact 11b of the vertical NPIJ Tr.
The base contacts 12'a and 12'b of the Tr are p''-regions formed in the same process as the high concentration p'l-region (inactive base) 12, and constitute part of the emitter and collector. 13' is an Ae electrode wiring.

Generally, the problems with horizontal PNPTrQ are as follows.

(2) Since the current (minority carriers) flows near the surface, it is very susceptible to the influence of the surface, and there is a lot of leakage current due to generation and recombination near the surface, so the current amplification factor hFE cannot be very high.

(2) When a bias voltage is applied to the emitter junction, the depletion layer does not extend toward the lateral base, so if the lateral base width (indicated by a in the figure) is short, punch-through is likely to occur.

■ Since the current flows horizontally, the device! 1 The dimension that determines gender is determined in the horizontal direction. Zunawaji,
Processing techniques such as photolithography, etching, and lateral extent of diffusion determine device properties. Therefore, the base width, which is important in determining the characteristics, is 3 to 41 zm, which is one order of magnitude larger than that of the vertical NPNTr.

■ Frequency characteristics d, wide base width, and vertical NPNT
Since there is no drift electric field like r, the frequency characteristics are poor and the gain bandwidth product (1) cannot be made high.

(2) Since the current flows in the horizontal direction, the Tr surface is also determined in the horizontal direction, and the internal area of the Tr is much larger than that of a vertical NPNTr.

In this way, the drawback (l-
1. Since the current flows in the lateral direction, the base width becomes wide, resulting in poor high frequency characteristics, and the internal area of the transistor becomes large. In fact, the area of the cylindrical PNPTr shown in FIG. 1 proposed by the present applicant is about three times larger than that of the vertical N P N 'ry.

In the role of IC, LSI, circuit membrane d1 earth blPN
It is desirable that both Tr and PNP Tr can be used. However, horizontal type PI Tr fJ, vertical type □VI
The high frequency characteristics are very poor compared to PNTr, and Tr
Horizontal PINP is not suitable for IC and LSI circuit films due to its large surface area.
It is often the case that circuits are designed using only vertical IN'Pi transistors, avoiding the use of transistors. Therefore, the circuit design is subject to major restrictions. IC,LS
In the role of I, if a vertical PNPTr having characteristics comparable to those of the vertical NPNTr can be used, circuit proposition 1 can be easily achieved and the circuit characteristics can be sufficiently exhibited. Therefore, a structure and process that can manufacture a vertical PNPTr that exhibits characteristics comparable to those of the vertical NPNTr are desired.

Purpose of the Invention In view of the above-mentioned problems, the present invention provides a vertical NPNTr.
It takes full advantage of the advantages of very good frequency characteristics, high speed, high density, and easy manufacturing.
The present invention provides an integrated structure that forms a vertical PNPTr whose high frequency resistance is on the same level as a vertical NPNTr in the JJ manufacturing process, and which is exactly the same as a vertical NPNTr in terms of performance and a method for manufacturing the same. .

Structure of the Invention According to the present invention, a vertical NPNTr and a vertical PNP Tr are formed in the same process in an island region separated between elements by a first insulating film, and in the vertical NPNTr, the emitter is surrounded by the first. Second. It is covered with a third insulating film, and the vertical P
In NPTr, the area around the emitter is the 4th. A fifth insulating film (formed in the same process as the second insulating film) between the emitter and collector: a sixth insulating film (the third
) is formed in the same process as the insulating film of
Achieving high density and high speed semiconductor integrated circuits, vertical NP
In NTr, lower part of insulating film of Ml; 3, vertical P N P T
In r, a semiconductor integrated circuit and a method for manufacturing the same are provided in which a P-type semiconductor region is formed in a self-aligned manner in a lower part of a sixth insulating film deeper than in other parts.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows the structure of a semiconductor integrated circuit according to the present invention (one embodiment) in which a vertical PNPTr is integrated.

In FIG. 2, the vertical NPN Tr has the same structure as the vertical NPNTr in FIG. 1, so it is indicated by the same number as in FIG. For the vertical PINP'l'r, regions formed in the same manufacturing process are indicated by the same number, and all are marked with ". In the figure, 3"a and 3"b are high concentration P regions υ, 3 "a" is formed directly under the atomic isolation oxide film 6, and serves as a channel stopper.

3"b is a feature of the present invention, and is formed in the entire island deposit area of the vertical PNPTt. Note that the buried layer 2 is a vertical NPN
Both the Tr and the vertical PNPTr are formed over the entire island region. These high concentration P regions 3, 3"a, 3"b are formed before forming the n-type epitaxial layer 4. After that, the n-type epitaxial layer 4, the element isolation oxide films 6, 6
, this high concentration P region diffuses upward. However, since inter-element isolation oxide films 6, 6" are formed in the region of 3.3"α, the high concentration P region that has diffused upward becomes an oxide film. However, since the region 3"b is an island region, the high concentration P region 3"b diffuses upward in the n-type epitaxial layer 4. Vertical PNPTr
An n+ buried layer 2 and a high concentration P region 3"b are in the island region
However, since the high concentration P region 3"b is not heat-treated before forming the n-type epitaxial layer 4,
It has not spread yet. When forming the n-type epitaxial layer 4 and the element isolation oxide films 5 and 6'', the high concentration P region 3''b is diffused. For example, n buried layer 2” is A
s, when the high concentration P region 3″b is formed of B, the temperature is 1000°C.
The diffusion coefficient of As in is about 2×1015 crl/s
The diffusion coefficient of eC,B is approximately 1.2 x 10 o+Vs
In ec, the diffusion coefficient of B is about 6 times that of 88.

Therefore, when forming the n-type epitaxial layer 4 and the element isolation oxide films 6 and 5'', the high concentration P region 3t is removed from the n+ buried layer 2.
Compared to 〃, it diffuses significantly upward.

After forming the element isolation oxide films 5, 5'' as shown in FIG. 6"a and 6"b separate the emitter of the vertical P1'4P Tr, which is formed in the same process as the base-collector isolation oxide film 6 of the vertical NPNTr. The oxide film 8" formed in the same process as the active base 8 is the p-region 9" which becomes part of the collector of the vertical P1 and Pl"r.
is polySt, 10'' is an oxide film formed in the same process as the emitter-base isolation oxide film 10, and is formed in a predetermined region of the collector in contact with the oxide film 6''b.

11" is emitter 11a1 collector contact 11b
The base contact of the vertical P14PTr is formed in the same process as 12"a and 12"b are the high concentration p + region (inactive base), the high concentration p region is formed in the same process as 12, and 12"a is the emitter, 12''b forms a collector contact. This high temperature p+ region 2”a, 1
The feature of the present invention is to form 2"b.
Contact 11'' is covered with a resist film and ion implantation is performed to form emitter 12''a1 oxide film 6''b, 1o''.

It is formed on the collector 8".The oxide film of 6"b is 60
Since the oxide film of 00 and 10" is formed by 1800 people, when B is implanted so that the ion beam up of the ion implantation becomes about 20008, the B implanted and broken on the oxide film 6"b is n.
Since it does not diffuse into the type epitaxial layer 4, the emitter and collector are separated in a self-aligned manner by this oxide film 6"b. Furthermore, the film thickness of the polySt 9" is 200 mm.
0, B has an oxide film 10" on the collector region.
A low concentration immediately below is implanted near the boundary between the region and the n-type epitaxial layer 4. Then,
By heat treatment, the highly doped p+ region 2''b, which is indented directly under the oxide film 10'', is connected to the high doped P region 3''b raised from below to form a collector contact. , the high concentration P+ region 2''a implanted on the emitter has a shallow Rp and is not connected to the high concentration P region 3''b, so the base width (already shown in the figure) is adjusted in a self-aligned manner.
form. This base width is determined by the step difference between the polySt 9" and the oxide film 1o, so it can be made as extremely thin as 0.2 μm. Therefore, it is possible to improve the high frequency characteristics and form a very high-speed vertical PNPTr. It will become.1
However, even with the same design rules, the area of this vertical PNPTr is approximately 1.2 times that of the vertical N P N Tt, which is significantly smaller than the conventional horizontal PNPTr, and greatly contributes to higher density. do. 13'' is A4 electrode wiring, and the device is completed with this.

An embodiment of a specific method for manufacturing a semiconductor integrated circuit to which the integrated structure of the present invention is applied will be shown below with reference to FIGS. 3A to 3G.

In FIG. 3A, 21 is, for example, a P-type semiconductor substrate, 2
Reference numeral 2 denotes an n+ implant layer, which is formed in a portion that will become an island region. A high concentration P region 23 is formed only on the element isolation region in the vertical NPNTr, and on the element isolation region and the island region in the vertical PNPTr. 24 is an n-type Evitaginyar layer with a thickness of 1.27 m. 25 is a base oxide film formed by 500 people, and 26 is a nitride film formed by 1000 people. 27 is patterned with resist I/film. Thereafter, using this resist film 27 as a mask, the nitride film 26, base oxide film 25, and n-type epitaxial layer are etched by 0.75 Ixn (FIG. 3(B)).
.

In FIG. 3C, a 1.6/1 m long folded film 28 is formed by selective oxidation using the nitride film 26 as a mask. At this time, a high-pressure oxygen isolation oxide film is formed by selective oxidation. The high-concentration P region 23b has an overhang of approximately 0.65 μm.

After that, the nitride film 26 is patterned again to form a vertical 'N'
An oxide film 29 of 6,000 layers is formed between the base and collector contact in the P N Tr, and around the emitter in the vertical PNP Tr. And vertical NPN
A collector wall 30 is formed in the Tr. Then, by ion implantation, the low concentration p-region 31 is formed into a vertical N
In P N Tr, the base region, &PNP Tr
In this case, it is formed to a depth of 0.4 μm in the collector contact portion (FIG. 3(D)).

In Figure 3E, poly St 32 is applied 2 times over the entire surface.
000 people formed the soil, and 600 people formed the nitride film 33 on the soil. Then, the nitride film 33 is patterned by foot lithography, and the polySt 32 and n-type epitaquin layer 24 are etched by 0.1 ltm. Then, 1800 oxide films 34 are formed by selective oxidation using the nitrided 9E 33 as a mask. This oxide film 34 is formed between the emitter and the base in the vertical NPNTr, and is formed on a part of the collector contact part from above the oxide film 29 in the vertical PNPTr.
The difference in level between the St 32 and the oxide film 34 is about 2,000.

After that, using the resist film as a mask, the high-accuracy meter area 35
Form a, 35b, and 35c to a depth of 0.2 μm (7). 35a, 3sb are vertical type 1P1Tr
35c forms the base contact in the vertical P14PTr. Then, by ion implantation again, the high concentration p10 region 36d is formed.

3eb, forming 36C. 36a is vertical type N P N
It forms an inert base in T r and has the effect of lowering the base resistance rbb/. 36b.

36c is the emitter and collector in the vertical PNPTr.
Contacts are formed respectively, and 36b and 36c are separated by an oxide film 29 in a self-aligned manner. In addition, since the ion range Rp has a step difference of 2000 between the poly St 32 and the oxide film 34, the high concentration p+ directly below the oxide film 34
The region 6c is connected to the high concentration P region 23b raised from below to form a collector contact. On the other hand, high concentration p region 3.6b formed in the emitter
7. is not connected to the high concentration P region 23b, so the n-type epitaxy is very weak. The base of the layer is created in a self-consistent manner. Moreover, since the (011 plane) of the emitter junction is covered with the oxide film 29, the junction capacitance is also minimized.

(Figure 3 (F)).

In FIG. 3G, a vertical NPN 1°r and a vertical PNPTr are completed by forming the electrode wiring 37.

As described above, the present invention has the following advantages:
Integration of Tr and vertical PNP'l''r 41' 17-bit integrated circuit uses a 41'structure; in vertical N P N
By forming the 1 oxide film and the emitter-base thickness 1 oxide 11, we minimized the junction capacitance on the sides of the junction field 11 knee, which is a factor that deteriorates the frequency characteristics, as much as possible. It is possible to increase the speed. Since the relatively high p1- region (inactive base) is formed in a self-aligned manner from the emitter end, it is possible to reduce the base resistance rbbl and further increase the speed. Vertical PN
PTr can be manufactured in exactly the same process as the structure and process of vertical i'J P N 'I'r, so there is no increase in the process, and the high concentration that was conventionally used as a channel stopper can be manufactured. The resistance area is vertical P
By forming it in the island region of NPTr, the element amount #i
After the oxide film is formed, the soil will be lifted upwards considerably.

In addition, the bacteria concentration p region is formed by ion implantation by utilizing the step between a slightly deeper oxide film (base-collector interspace film) and a shallower oxide film (emitter-base interlayer oxide film).
The high concentration p+ region is not formed directly under the slightly deep oxide film, but the high concentration resisting region is formed directly under the shallow oxide film, so the high concentration resisting region is separated by the slightly deeper oxide film in a self-aligned manner. , emitter and collector contacts in the branched P zIIPTr are formed. In the nest? I#l
Since the high kkp''-region is formed by using the step of the /'1m film, the area directly under the thin oxide film is formed deep in self-alignment, and the area directly under the collector contact portion is shallow. The high concentration resistant region formed directly under the thin oxide film is
It is connected to the high concentration resistant region formed in the island region of the vertical PNPTr and lifted upward, making it possible to make collector contact. On the other hand, the high-concentration p+tt region formed directly under the emitter is not connected to the high-concentration resistance region that has been lifted in two directions, so a very short base width can be formed in a self-aligned manner, which is the same as that of a vertical NPN Tr. It is possible to obtain high frequency characteristics of a certain degree, and it is possible to achieve extremely high speeds. Also, since the current flows vertically, the horizontal Pin
It does not have a large area like P'rr, but is vertical N P N
Since it can be formed with approximately the same size as 'l''r,
It is possible to achieve high density.

Effects of the Invention As described above, the vertical 1iPNTr and vertical PN' of the present invention
The integrated structure of PTr is vertical i (Pi4 Tr, ii
<Both types of PNPTr can maintain very high frequency characteristics, are high speed, and have high density, so they can easily play a role in the anatomy of ICs and LSIs, and can demonstrate their circuit characteristics to their subordinates, so they will be useful in the future. It has greatly contributed to the development of VLSI and has extremely high industrial value.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an integrated structure of a vertical N'P N Tr and horizontal P1 to P Tr using the insulation isolation method already proposed by the applicant, and FIG. 2 is a cross-sectional view of an integrated structure of a vertical NPNTr and a vertical PNPTr of the present invention. Structural cross-sectional views and FIGS. 3A to 3G are manufacturing process diagrams of essential parts of a semiconductor integrated circuit according to one embodiment of the present invention. 3.3"a, 3"b, 23.23a, 23b ---
... High concentration P region, 6,5", 28...... Inter-element isolation oxide film, 6,6"a, 6"b, 29...
Base-collector isolation oxide film, 10, 10", 34.
...Emitter-base separation oxide film, 12°12
"a, 12"b, 36a, 36b,,,96c*
**＋・・High concentration resistance area.

Claims (3)

[Claims] (1) A bipolar semiconductor integrated circuit in which elements are isolated by a first insulating film, wherein a collector contact is formed between the first insulating film and the second insulating film, and a collector contact is formed between the first insulating film and the second insulating film; A base contact portion is formed at 1bJ with an insulating film having an insulating film strength of 3, and the entire region of the 111j plane of the emitter is covered with an insulating film including at least the second insulating film and the third insulating film, and the third
deep at the bottom of the insulating film, shallow at the base contact part,
A vertical (l→PN) run lister having an inert base formed continuously in a continuous manner, and an emitter formed at the same concentration and depth as the inert base under the base contact, and the emitter The fourth insulating blade has the same depth as the second insulating blade. By the fifth insulating film! The emitter and collector contact portions are covered by the fourth insulating film p+tt, and the emitter and collector contact portions are covered by the first insulating film. The collector contact is formed between the fourth insulating film and the first insulating film.
1. A semiconductor integrated circuit comprising a vertical PNP run lister in which a base contact portion is formed between the semiconductor integrated circuit and the sixth insulating film. (2) First. between the fourth insulating film and the first insulating film. A patent characterized in that the sixth insulating film is shallower than the fourth insulating film and is formed in contact with the fourth insulating film, and the collector contact portion is deep under the sixth insulating film. A semiconductor integrated circuit according to claim 1. (3) Vertical N P N l / Run lister and vertical PNP
This is an integrated manufacturing process for transistors, in which the first insulating film divides the transistors into vertical PNP and vertical N'P transistors.
The first.N transistors are formed respectively. forming a second island region and forming a P-type semi-dedicated region over the entire first island region, and forming a second insulating film between the base and the collector contact portion in the second island region; , emitter and pace contact] - A third insulating film between the parts, and a fourth insulating film in the first m and d regions, and a fourth insulating film around the emitter. forming a sixth insulating film between the emitter and the collector contact portion and in contact with the fourth insulating film; and forming a sixth insulating film in the second island region; The lower part is deep, and the base contact part is shallow and continuous to form an inactive base, and in the first island region, the emitter region and the collector contact part have the same depth as the base contact of the second island region. A method for manufacturing a semiconductor integrated circuit, comprising the step of forming the collector contact portion at the same concentration, and forming the collector contact portion deeper below the sixth insulating film than other portions.