JPH0461268A - Integrated circuit device and manufacture thereof - Google Patents

Abstract

PURPOSE:To extend the base width of a large signal transistor and to control its hFE to be smaller than hFE of a small signal transistor and a suitable value by forming a low concentration base region having a lower impurity concentration than that of the base region in the bottom of the base region of a large signal transistor having a relatively high impurity concentration. CONSTITUTION:A well region 23 and a low concentration base region 28 of a large signal transistor 25 are simultaneously formed. The entire region 28 is so superposed as to be covered with a base region 26. Since the transistor 25 has the region 26 and the region 28 under an emitter region 27, its impurity concentration profile has inclinations of two stages of a relatively abrupt slope to be formed of the region 26 of a relatively high impurity concentration and a smooth slope to be formed of the region 28 of a relatively low impurity concentration.

Description

Detailed Description of the Invention (a) The invention satisfies all of ICmax and B-resistance h and v- in the field of industrial application.
You can get 5 Stars) 1! , relating to conductor integrated circuits.

(b) The conventional technology semiconductor integrated circuit e uses each diffusion region in common i=−rXL
Since there is a basic technical idea -r, which simplifies the equation, each circuit element is composed of a common diffusion region 1, and an element of f (NPN l). -La', S,
・Star) had the same characteristics in all (, r::.

However, ICs for consumer use, especially for acoustics, often incorporate output stage transistors and output stage transistors at the same time as various signal processing circuits, and due to circuit requirements, small signals for signal processing are There is a demand for making the 11-stream amplification factor h□ different between the transistor (transistor) transistor and the large signal transistor transistor for the output stage. In other words, the h□ of the small signal transistor is 1
00 to 200, when large signal transistor glue,
This is a request to lower G to about 50 and increase the G-actor current Iemax.

By means of changing h□ in this way, -1. For example, the base regions can be formed separately as described in Japanese Patent Application Laid-Open No. 60-7075653'. There is a means.

That is, as shown in Figure 3, Evita 4 Jal J! ! A base region (5) for a small signal transistor (4) and a base region (7) for a large signal transistor (6) are provided in each island (3) obtained by separating (1) by an isolation region < 2. They are formed individually. At this time, large signal transistor (6)
Two methods can be considered for the base region (7).

One is to set the impurity concentration high to reduce h□ (Fig. 4, plan 1), and the second is to deepen the diffusion depth (widen the base width) to reduce h□ (Fig. 4, plan 1). Fig. 2 draft).

(8) Invention tries to solve! #! However,
The above-mentioned method had the disadvantage that it could not be made that high because of the saturation limit of boron with respect to silicon crystal, and therefore there was a limit to lowering h□. Moreover, in addition to the fear of breakdown voltage deterioration due to Zener breakdown, when the base region (7) is formed by ion implantation, the dose amount increases and the processing time becomes longer, resulting in complications such as ``TT'' and Il. Although the latter method is consistent with VJ in that it increases Jet Since ψ-, which caused ψ-, Iemax increases, and the disadvantage of not having it is eliminated.From this -, if h□ is the same, the concentration of the base is 1, which can increase eaiax.2.

stop.

1-1 Even if both the impurity concentration and base width are controlled, hFI! It was still difficult to satisfy both of ICmax and ICmax.

2) Means for Solving the Problems The present invention has been made in view of the above-mentioned drawbacks of the conventional art. By forming a low concentration base region (28) having an impurity concentration lower than that of the small signal transistor (16), a large signal transistor (28) having an impurity concentration lower than that of the small signal transistor (16) can coexist, and Area (28) and I I L (
Coexistence with IIL is also attempted by forming the well region (23) of 20) at the same time.

(*) Effect According to the present invention, by superimposing the low a11I-base region (28), the width of the large signal (25) is expanded, so the small value 17j, l)
- Seeds, evening (16), □ to an appropriate value of 11 smaller than 4' Bi). Moreover, a part of the base is a 4-゛ base region with a relatively high impurity concentration.
6) Since it is composed of #, the maximum nearness and lid t 't1t
You can increase Icmaz. Then, the low concentration base area 28) of the Daishin 11 transistor (25) is
Since the low concentration of (2O) is formed at the same time as the region (23), they can coexist efficiently.

(F) Example An example of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view, not showing a semiconductor integrated circuit according to the present invention. In the same figure, (11) is P-type ')' non-A,
Crystal substrate, (12) is an N-type 14 bitaxial layer grown on the surface of the substrate (11), (18) is formed, (13) is an N7,91 buried layer, and (14) is buried! 'Pi
A bi) P + type separation region surrounding (13) and penetrating through the axial layer (12), (I5) is separated by the separation region (14) with One of the 6゜ islands (15) is the 4゛-P-shaped base region (17), which forms the small leaf 1-7) jista (16〉)!
= N″ type gomitter region (18) is formed, and the eye-
7> A vertical NPN transistor is formed using the dots (15) as the opening and lid. (19) is N' type 2y L vector]
/7)・area==.

Other I-7>)'(15) has I I L(20>
In order to form a P-type injector region (21) and an external base region (22), a P”-type well region <23), N+
Mold: Form an IL/lid area (24) (7. Use the IL/lid area (23) as a base for a reverse direction vertical inverter) and form a transistor 1'11L. Two areas (23
) as the base, the carry of the base ＼ from -1 mitter of the inverter transistor? Since the base is close to the N'' type buried layer (13) which is the main body of implantation 2-, a high inverse β can be obtained.

EL, t\ History and other islands (15) are Daishin Tei]・
U.]...Resta (25〉 evening) In addition to forming a P-type base area (26) and an N'' type 1-chomitter area (27), a layered plate was added to the base area (26〉). -P- type low concentration base region (28) was formed.
・Riricontact]・area, (30) is the S/R 7〉 oxide film, and (31) is each electrode C. Base region (1,7>(
26) and the gomitter region (IU (27)) were formed in the same process. Also, the well region (23) of II1., (2O) and the low voltage transistor (25) of the large signal transistor The concentration base region (28) was formed at the same time.

The IIL well region (23) is as described above. Since the purpose is to bring the base-1-mitter junction close to the buried layer (13), the diffusion depth is deep and the impurity concentration is low in order to increase the inverse β. Specifically, the base regions (17) and (26) have a surface concentration of 1011011ato
σ-1, with a diffusion depth of 1.0-1.5μ, whereas the well region (23) has a surface concentration of 10′1-1,0.
Ita, toms-cri-”, diffusion depth 2.0-3
．． Formed to 0μ.

Since the well region (23) and the low-a degree / low concentration region (28) of the large signal transistor (25) are formed at the same time, the low concentration / base region (28) is naturally formed as described in L.1. The purity concentration and depth should be selected. , In this way, the concentration of dull substances can be lowered [In addition, if the surface depletion of impurities is
Since there is a concern that t may increase, the low concentration base region (28
) was formed so as not to protrude from the base region <26). -,,)1, the low concentration base region (28) is overlapped so as to cover the entire surface of the Hess region (26)T.

Large signal] The transistor (25) is the emitter region (27)
A base region (26) and a low concentration base region (2
8) and 4, the impurity concentration L1 file has a distribution as shown in FIG. That is, the relatively steep slope formed by the base region (26) with a relatively high impurity concentration, and the low concentration base region (28) with a relatively low impurity concentration.
It has two levels of slope: a gentle slope formed by . As a result, the base width W of the large signal transistor (25) is determined by the diffusion depth of the low concentration base region (28) as shown in the same figure, so the base width W of the large signal transistor (25) is determined by the diffusion depth of the low concentration base region (28), so the base width W of the large signal transistor (25) is determined by the diffusion depth of the low concentration base region (28). The width can be increased, and the current amplification rate can be increased. can be made small. Since this is a region of low impurity concentration, there is no need for h□ to be too large. At the same time, a large signal (・
c) Since the base of the transistor 25 overlaps with the base region (26) with a relatively high impurity concentration due to base diffusion, there is little influence from conductivity modulation of the base, and therefore the increase in Iemax obtained by lowering hyw. can be extracted as effectively as possible.

FIGS. 2A to 2D illustrate a method of manufacturing the integrated circuit of the present invention.

First, as shown in FIG. 2A, an epitaxial layer <12) is formed on a substrate (11) on which a buried layer <13) and one side isolation region (14) are formed, and boron (B) is added to a low concentration base region (14). 28) The epitaxial layer (12) is formed by selectively implanting ions at a required dose into the portion corresponding to the L region (23) and heat-treating the entire substrate (11) as shown in FIG. 2B. Boron doped on the surface (B,
) to a desired depth to form an upper isolation region (14) as shown in FIG. The base region (17) of the small signal To〉 Sea Stuff 16) and the base region (27) of Inushin M (・; Angister〈?5), I I L (2,,
The external △, . The emitter regions (18) (27) of the signal transistor (25), and I I L (gQ
) to form a ``-lucta region (24).

In the configuration of the present invention, the diffusion depth does not change even if a certain amount of heat treatment is applied, and base diffusion is performed on the already diffused low concentration base region 28) to form a small signal transistor (bo) and a large signal transistor (25). Since the base diffusion is formed, a controlled diffusion can be performed for the small signal transistor (16). Therefore, it is extremely easy to control the characteristics of both the small signal transistor (16) and the large signal transistor (μs).

(g) Effects of the Invention As explained above, according to the present invention, by overlapping the low concentration base region (28) on the large signal transistor (25), the small signal transistor (16) with high h It has the advantage of being able to easily coexist with a small large signal transistor (25). Also, large signal transistor 2
Since the base of 5) overlaps with the base region (26) having a relatively high impurity concentration, Ie due to conductivity modulation
It has the advantage that the drop in max is small and therefore 1co+ax can be maximized.Furthermore, by increasing the large signal transistor (25〉), the ASO can be increased, making it suitable as an output stage transistor. It also has the advantage of being able to be manufactured with specific characteristics.In addition, the low concentration base region (
28) has the advantage that the characteristics of both large and small signals can be easily controlled.

Furthermore, the low concentration base region (28) of the large signal transistor <25) is the well region of I I L (20)
23), it also has the advantage that three types of elements can coexist without increasing the manufacturing process.

[Brief explanation of the drawing]

Fig. 1 is a sectional view for explaining the present invention, Fig. 2 A-D
3 is a sectional view for explaining the manufacturing method, FIG. 3 is a sectional view for explaining the conventional example, FIG. 4 is a diagram showing the conventional impurity concentration distribution, and FIG. 5 is the impurity concentration distribution of the present application. FIG.

Claims (5)

[Claims] (1) An epitaxial layer of an opposite conductivity type formed on a semiconductor substrate of one conductivity type, a plurality of islands formed by separating the epitaxial layer, and a first transistor to form a first transistor. A base region of one conductivity type formed on the surface of the island, an emitter region of opposite conductivity type formed on the surface of the base region, and a base region of one conductivity type formed on the surface of the second island to form a second transistor. a base region; an emitter region of opposite conductivity type formed on the surface of the base region; and a low concentration base region formed overlapping the base region of the second transistor, which is deeper than the base region and has a lower impurity concentration than the base region. , an injector region of one conductivity type formed on the surface of the third island, an external base region, a collector region of the opposite conductivity type, and a lightly doped base region of the second transistor were formed simultaneously to form the IIL. A semiconductor integrated circuit comprising a well region. (2) the base region of the first transistor and the second transistor;
2. The semiconductor integrated circuit according to claim 1, wherein the base region of the transistor, the injector region and the external base region of the IIL are formed simultaneously. (3) The semiconductor integrated circuit according to claim 1, wherein the second transistor constitutes an output transistor. (4) The semiconductor integrated circuit according to claim 1, wherein the base region of the second transistor overlaps the low concentration base region so as to completely cover it. (5) Forming an epitaxial layer of opposite conductivity type on a semiconductor substrate of one conductivity type, ion-implanting an impurity of one conductivity type into the surface of the epitaxial layer and diffusing it to a desired depth to form a large signal transistor. forming a low concentration base region and an IIL well region, selectively diffusing impurities of one conductivity type into the surface of the epitaxial layer to form a base region for a small signal transistor and a low concentration base for the large signal transistor; forming a base region shallower than the base region and overlapping with the low concentration base region and having an impurity concentration higher than the low concentration base region, and an injector region and an external base region of the IIL; selectively introducing impurities of opposite conductivity type; forming an emitter region on the surface of the base region of the signal transistor, an emitter region in a portion where the low concentration base region of the large signal transistor and the base region overlap, and a collector region on the surface of the well region of the IIL. A method for manufacturing a semiconductor integrated circuit, characterized by: