JP3469593B2 - BiCMOSIC - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BiCMOS IC, and more particularly to a BiCMO in which a semiconductor element is formed on a second conductivity type epitaxial growth layer formed on a first conductivity type semiconductor substrate.
Regarding SIC. 2. Description of the Related Art FIG. 2 is a sectional view showing a pad portion of a CMOS IC. In the drawing, 1 is an n-type semiconductor substrate, 2 is a p-type well, 3 is a field insulating film, 4 is an electrode pad made of aluminum, 5 is an overcoat film, 6 is a window opening of the overcoat film 5, 7 is Connect wire. The p-type well is formed so as to be located below the pad 4, and has a function of preventing a short circuit due to the crack 10. That is, since a force is applied to the pad 4 by wire bonding at the time of wire bonding, a crack 10 may enter the field insulating film 3. for that reason,
There is a possibility that a defect that the pad 4 and the substrate 1 are short-circuited through the crack 10 may occur. Therefore, p under pad 4
The mold well 2 is provided so that the portion short-circuited to the pad 4 by the crack 10 is bonded and separated from the n-type semiconductor substrate 1. [0004] By the way, BiCMO
In the SIC, an n-type epitaxial growth layer is generally formed on a p-type semiconductor substrate.
Even if a technique of providing a p-type well under the pad shown in FIG. 2 in the OSIC was used, a short circuit due to a crack could not be prevented. This is because the p-type well is in direct contact with the p-type semiconductor substrate. Accordingly, if a short circuit occurs between the p-type well and the pad due to a crack, the product becomes a defective product and causes a reduction in yield. However, in the BiCMOS IC, there is also a short-circuit prevention method in which a portion of the n-type epitaxial growth layer below the pad is surrounded by a ring-shaped p-type well. Can be junction-separated from the substrate and other parts of the n-type epitaxial growth layer. However, according to such a technique, a portion of the n-type epitaxial growth layer below the pad must be surrounded by a ring-shaped p-type well.
An element such as a protection diode cannot be formed near the pad. Therefore, there is a problem that high integration of the IC is hindered. SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and has a high integration of IC in a BiCMOS IC in which a semiconductor element is formed on a conductive type epitaxial growth layer formed on a first conductive type semiconductor substrate. It is an object of the present invention to prevent a short circuit between a pad and a substrate due to a crack under a pad without hindering the formation of a circuit. [0007] The present invention BiCMOSIC
Is provided on a first conductivity type semiconductor substrate, a second conductivity type epitaxial growth layer having a semiconductor element including a bipolar transistor at least partially forming a collector, and on a field insulating film covering the second conductivity type epitaxial growth layer. In a BiCMOS IC having a pad above a portion where the semiconductor element is not formed, a first conductivity type well having a first conductivity type channel MOS transistor inside a portion below the pad of the second conductivity type epitaxial growth layer At the same time, a first conductivity type well formed is provided, and between the first conductivity type well formed in a portion under the pad of the second conductivity type epitaxial growth layer and the first conductivity type semiconductor substrate, The first conductivity type well and the second conductivity type epitaxial growth layer are combined with the first conductivity type well. Wherein the second conductive type buried layer for electrically isolating is formed from first conductivity type semiconductor substrate. According to the BiCMOS IC of the present invention, the first conductivity type well is formed in a portion that is short-circuited with the pad when a crack occurs in a portion below the pad of the field insulating film. Junction can be separated from the conductive type epitaxial growth layer. Further, since the second conductivity type buried layer is formed between the first conductivity type well and the first conductivity type semiconductor substrate, the second conductivity type buried layer is provided between the pad and the first conductivity type semiconductor substrate. The layers can be joined and separated. Thus, it is possible to prevent the occurrence of a short circuit due to a crack formed under the pad, and to improve the yield. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a BiCMOS IC of the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows the BiCMOSI of the present invention.
It is sectional drawing which shows one Example of C. In the drawing,
1p is a p-type semiconductor substrate, 8 is an n-type epitaxial growth layer, and 2 is a p-type well formed in a portion of the n-type epitaxial growth layer 8 under the pad (4). Reference numeral 9 denotes the p-type well 2 and the p-type semiconductor substrate 1p
And an n-type buried layer provided therebetween, which is electrically separated by bonding. Reference numeral 3 denotes a field insulating film, 4 denotes an electrode pad made of aluminum, 5 denotes an overcoat film, 6 denotes a window opening thereof, and 7 denotes a connect wire. still,
The BiCMOS IC shown in FIG.
The same reference numerals are used for the same parts as in (IC), and the description thereof is omitted, and only different points are described. According to such a BiCMOS IC, n
Since the p-type well 2 is formed in a portion of the field type epitaxial growth layer 8 under the pad 4, even if a crack 10 occurs in the portion of the field insulating film 3 under the pad 4 during wire bonding, the p-type well 2 and the pad 4 Is merely short-circuited, and the p-type well 2 and the n-type epitaxial growth layer 8 are separated by a junction.
Therefore, it is possible to prevent a short circuit caused by a crack 10 caused by wire bonding between the pad 4 and the n-type epitaxial growth layer 8. Then, the p-type well 2 and the p-type semiconductor substrate 1
Since the n-type buried layer 9 is provided between the p-type well 2 and the p-type semiconductor layer 1p, the p-type well 2 and the P-type semiconductor substrate 1p can be separated. Therefore, it is possible to prevent a short circuit due to the crack 10 generated at the time of wire bonding between the pad 4 and the p-type semiconductor substrate 1p. Further, by forming the p-type well and the p-type semiconductor substrate 1p under the pad 4, short-circuiting due to cracks under the pad 4 due to wire bonding can be prevented, which prevents high integration of ICs. Can be done without. In the case of BiCMOS IC, n
The epitaxial growth layer 9 can be formed simultaneously with the n-type collector of the npn bipolar transistor, and the p-type well 2 can be formed simultaneously with the p-type well in which the n-channel MOS transistor is formed.
Therefore, without increasing the manufacturing man-hours of BiCOMSIC,
In addition, a short circuit due to a crack generated under a pad by wire bonding can be prevented without hindering high integration, and the yield can be improved. According to the BiCMSIC of the present invention, a second conductivity type epitaxial growth layer having a semiconductor element including a bipolar transistor at least partially forming a collector is provided on a first conductivity type semiconductor substrate. In a BiCMOS IC having a pad above a portion where the semiconductor element is not formed on the field insulating film covering the conductive type epitaxial growth layer, a portion of the second conductive type epitaxial growth layer below the pad has a first conductive inside. A first conductivity type well formed simultaneously with the first conductivity type well having the type channel MOS transistor, wherein the first conductivity type well is formed in a portion of the second conductivity type epitaxial growth layer under a pad; The first conductivity type wafer is provided between the first conductivity type semiconductor substrate and the first conductivity type semiconductor substrate. A buried layer of a second conductivity type, which electrically separates the semiconductor substrate from the first conductivity type semiconductor substrate with the second conductivity type epitaxial growth layer. BiCM of the present invention
According to the OSIC, the first conductivity type well is formed in a portion that is short-circuited with the pad when a crack occurs in a portion under the pad of the field insulating film, so that a gap between the pad and the second conductivity type epitaxial growth layer is formed. Can be joined and separated. Further, since the second conductivity type buried layer is formed between the first conductivity type well and the first conductivity type semiconductor substrate, the second conductivity type buried layer is provided between the pad and the first conductivity type semiconductor substrate. The layers can be joined and separated. Thus, it is possible to prevent a short circuit from occurring due to a crack generated under the pad, and to improve the yield.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing one embodiment of a BiCMOS IC of the present invention. FIG. 2 is a cross-sectional view illustrating a pad portion of a CMOS IC for explaining background art. [Description of Signs] 1p First conductivity type semiconductor substrate 2 First conductivity type well 3 Field insulating film 4 Pad 8 Second conductivity type epitaxial growth layer 9 Second conductivity type buried layer

Continuation of front page       (56) References JP-A-56-8852 (JP, A)                 JP-A-61-53756 (JP, A)                 JP-A-63-117466 (JP, A)                 JP-A-61-274343 (JP, A)                 JP-A-3-273640 (JP, A)                 Shokai Sho 51-77058 (JP, U)

Claims (1)

(57) to the Claims 1 first conductivity type semiconductor substrate, at least
A half including a bipolar transistor partly forming a collector
BiCMOS having a second conductivity type epitaxial growth layer having a conductive element and having a pad above a portion of the field insulating film covering the second conductivity type epitaxial growth layer where the semiconductor element is not formed
In the IC , a first conductive type channel MOS transistor is provided inside a portion of the second conductive type epitaxial growth layer below the pad.
First well formed simultaneously with the first conductivity type well having
A conductivity type well is provided, and a well is provided under a pad of the second conductivity type epitaxial growth layer.
And the first conductive well formed on a portion that, the first
A second conductivity type buried layer for electrically separating the first conductivity type well from the first conductivity type semiconductor substrate with the second conductivity type epitaxial growth layer is formed between the first conductivity type well and the second conductivity type epitaxial growth layer; A BiCMOS IC characterized in that :