JP2004304107A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device with an electrode extraction structure which can prevent the step cut of a metal electrode provided on a high impurity concentration diffusion layer of the semiconductor device, and to provide its manufacturing method. <P>SOLUTION: Insulating films 4a, 4b, and 4c are composed of laminated layers of two or more different insulating films partitioning a semiconductor element region selectively provided at a semiconductor substrate 1. The insulating film 4c laminated on the uppermost part is formed so as to cover the side face part on the selective aperture side and to reach the high impurity concentration diffusion layer. Accordingly, it can prevent a clearance like an eave from being formed on the selective aperture side face because of excessive etching to a specific insulating film only by the chemical etching to be executed at the time of forming the selective aperture. Also, a second selective aperture 6b is formed smaller than a first selective aperture 6a. The laminated structure of the insulating film is made into a terrace shape. As a result, the steep surface shape of the selective aperture can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device having an improved electrode extraction structure from a diffusion layer region on a semiconductor substrate and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, high integration and miniaturization of semiconductor devices have been remarkably advanced, and there has been a tendency to be reduced in size and thickness due to surface mounting. For this reason, there has been a problem that no problem has occurred in the past. To solve this problem, improvements in the structure of the semiconductor device, improvements in the manufacturing method, and the like have been proposed (see Patent Document 1).
[0003]
FIG. 5 is a structural sectional view of a semiconductor chip described in Patent Document 1.
[0004]
In the semiconductor chip shown in FIG. 1, first, a silicon dioxide film 3 is selectively formed on an N-type silicon substrate 1, and a P-type diffusion layer 2 is formed on an N-type silicon substrate 1 partitioned by the silicon dioxide film 3. I do. Further, insulating films 4a, b, and c such as a silicon dioxide film, a silicon nitride film, and a phosphor silicate glass are deposited thereon by a chemical vapor deposition (CVD) method. Next, selective openings 6 reaching the P-type diffusion layer 2 are formed on the insulating films 4a, 4b and 4c by chemical etching, and a metal electrode 5 made of aluminum is provided thereon.
[0005]
[Patent Document 1]
JP-B-54-35069 (page 3, FIG. 9)
[0006]
[Problems to be solved by the invention]
According to the structure of the conventional semiconductor device as described above, two or more insulating films are stacked on the silicon dioxide film 3 serving as an element isolation region. Above the insulating film 4c is several hundred nm or higher, and has a very steep shape. Further, since the etching rates of the respective insulating films are different, only the layer of the specific insulating film is excessively etched by the chemical etching performed at the time of forming the selective opening 6, so that a part of the side surface of the selective opening 6 is scooped. A void like an eaves is formed. For this reason, the step coverage in the opening of the metal electrode 5 deposited on the selective opening 6 is deteriorated, and the step of the metal electrode 5 is caused.
[0007]
In other words, there has been a problem in that the electrode structure on the chip surface is disconnected, causing a problem in the electrode structure and affecting the characteristics and quality of the semiconductor device. In addition, this problem tends to become more remarkable as the integration and miniaturization of the semiconductor device increase.
[0008]
Therefore, the present invention has been made in view of the above-described conventional circumstances, and an object of the present invention is to provide a semiconductor device and a method of manufacturing the same, which can solve the above-described problems inherent in the conventional technology.
[0009]
[Means for Solving the Problems]
The semiconductor device according to the present invention includes an insulating film for partitioning a semiconductor element region selectively provided on a semiconductor substrate, a diffusion layer having a high impurity concentration provided in the semiconductor element region, and provided on the diffusion layer. An electrode structure including a selective opening and a metal electrode selectively provided on the selective opening, wherein the insulating film is formed by laminating two or more different insulating films, and is laminated on the uppermost portion. The insulating film covers the side surface on the selective opening side and reaches the diffusion layer having a high impurity concentration. Further, in an insulating film formed by laminating two or more different insulating films, the side surface on the selective opening side of the insulating film is laminated in a terrace shape.
[0010]
In addition, the method for manufacturing a semiconductor device according to the present invention includes a step of selectively forming an insulating film for partitioning a semiconductor element region on a semiconductor substrate; and a step of forming a high impurity concentration diffusion layer in the semiconductor element region. A step of forming various insulating films on the semiconductor element region, a step of forming a first selective opening reaching the high impurity concentration diffusion layer in the insulating film, and the first selective opening Forming a single insulating film covering the entire surface of the semiconductor element region, and forming a second selective opening smaller than the first selective opening reaching the high impurity concentration diffusion layer; Forming a conductive film for an electrode reaching the diffusion layer having a high impurity concentration through the second selective opening.
[0011]
According to the present invention, disconnection of the electrode can be prevented by improving the electrode structure in the semiconductor device. Therefore, a semiconductor device having good characteristics and high reliability and a method for manufacturing the same can be provided.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a structural cross-sectional view of a semiconductor chip for describing an embodiment of a semiconductor device according to the present invention, and FIGS. 2A to 4J are process cross-sectional views showing a manufacturing method thereof. is there.
[0014]
As shown in FIG. 1, a silicon dioxide film 3 is selectively provided on an n-type silicon substrate 1, and a p-type diffusion layer 2 is formed on an n-type silicon substrate 1 partitioned by the silicon dioxide film 3. Is formed. On the silicon dioxide film 3, insulating films 4a, b, c such as a phosphor silicate glass, a silicon nitride film, and a silicon dioxide film are deposited, and the insulating films 4a, b, c located on the P-type diffusion layer 2 are formed. Is formed with a selective opening 6 reaching the P-type diffusion layer 2, the uppermost insulating film 4c covers the side surfaces of the insulating films 4a and 4b on the selective opening 6 side. Has reached. A metal electrode 5 made of a metal such as aluminum which reaches the P-type diffusion layer 2 through the selective opening 6 is selectively deposited thereon. On the back surface of the N-type silicon substrate 1, a back surface electrode 7 is formed.
[0015]
According to this structure, the uppermost insulating film 4c covers the side surface of the insulating films 4a and b thereunder on the side of the selective opening 6, and the laminated structure of the entire insulating film has a spherical shape. For this reason, there is no gap like an eave on the side surface in the selective opening 6 and the sharp surface shape of the selective opening 6 is relaxed, so that the step coverage in the opening of the metal electrode 5 is remarkably improved. Have been. Therefore, it is possible to prevent disconnection of the metal electrode which is observed in the conventional electrode extraction structure of the semiconductor device.
[0016]
Next, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 2A and 2B, a silicon dioxide film 3 having a thickness of about 600 nm is formed on an N-type silicon substrate 1 by a usual pyrogenic steam oxidation method, and a photoresist 8 having a predetermined pattern is formed. Is formed, and the silicon dioxide film 3 is selectively etched and removed using the mask as a mask, thereby defining a semiconductor element region. Next, as shown in FIG. 2C, boron nitride is deposited on the N-type silicon substrate 1 partitioned by the silicon dioxide film 3, and the boron is thermally diffused into the N-type silicon substrate 1 in a diffusion furnace. By doing so, the P-type diffusion layer 2 is formed.
[0017]
As shown in FIG. 2D, insulating films 4a and 4b such as a phosphor silicate glass, a silicon nitride film, and a silicon dioxide film are sequentially deposited thereon by a chemical vapor deposition method. Next, as shown in FIGS. 3E and 3F, the first selective openings 6a reaching the P-type diffusion layer 2 are formed in the insulating films 4a and 4b located on the P-type diffusion layer 2 in a predetermined pattern. Is formed by chemical etching using the photoresist 8 as a mask, and as shown in FIG. 3 (g), only one type of insulating film such as silicon dioxide or silicon nitride is deposited thereon. .
[0018]
Next, as shown in FIG. 3 (h) and FIG. 4 (i), the insulating film 4c located on the P-type diffusion layer 2 is smaller than the first selective opening 6a reaching the P-type diffusion layer 2. The second selective opening 6b is formed by forming a photoresist 8 having a predetermined pattern and using this as a mask by chemical etching. Next, as shown in FIG. 4 (j), aluminum is grown to a thickness of about 4 μm by vacuum evaporation and patterned by photolithography to form a metal electrode 5 made of aluminum. An alloy made of gold, antimony, and nickel is grown to a thickness of about 2 μm on the back surface of the silicon substrate 1 by electron beam evaporation to form a back electrode 7.
[0019]
Since the selective opening is formed twice, the insulating film 4c deposited on the uppermost portion covers the side surface on the selective opening side. In addition, since the second selective opening 6b is smaller than the first selective opening 6a, the laminated structure of the insulating film is on a terrace. Thereby, it is possible to prevent the specific insulating film from being excessively etched by the chemical etching and to form a gap like an eave on the inner side surface of the selective opening 6, and at the same time, to have a steep surface shape of the selective opening. Can be improved. That is, the step coverage in the opening of the metal electrode 5 is improved, and it is possible to prevent disconnection of the metal electrode.
[0020]
In the above embodiments of the present invention, a PN junction diode and a method of manufacturing the same have been described. However, the present invention is not limited to this, and the electrodes or wiring of semiconductor devices such as Schottky barrier diodes, transistors, and ICs are taken out. It is applicable to the structure.
[0021]
【The invention's effect】
According to the present invention, in an insulating film composed of a stack of two or more different insulating films that partition a semiconductor element region selectively provided on a semiconductor substrate, the insulating film stacked at the top is selectively opened. Because the side surface of the side is covered and reaches the diffusion layer with high impurity concentration, only the specific insulating film is excessively etched by the chemical etching performed at the time of forming the selective opening, and the like The formation of voids can be prevented. In addition, since the second selective aperture is smaller than the first selective aperture, the laminated structure of the insulating film has a stepped shape, so that the steep surface shape of the selective aperture can be improved. That is, the step coverage in the opening of the metal electrode is improved, and disconnection of the metal electrode can be prevented.
[0022]
Therefore, according to the present invention, it is possible to provide a semiconductor device having good characteristics and high reliability by preventing disconnection of an electrode on the surface of a semiconductor chip.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a chip structure of a semiconductor device according to an embodiment of the present invention; FIG. 2 is a process cross-sectional view of a method of manufacturing a semiconductor device according to an embodiment of the present invention;
(A) Cross-sectional view in which a silicon dioxide film and a photoresist are formed on a substrate (b) Cross-sectional view in which a semiconductor element region is formed (c) A state in which a P-type diffusion layer is formed on a partitioned substrate FIG. 3 is a cross-sectional view of a state in which an insulating film is deposited and formed on a P-type diffusion layer. FIG. 3 is a cross-sectional view of a process in a method for manufacturing a semiconductor device according to an embodiment of the present invention.
(E) A cross-sectional view in which a predetermined photoresist is formed in the insulating film. (F) A cross-sectional view in a state in which a first selective opening is formed in the insulating film. (G) Only one type of insulating film is deposited thereon. FIG. 4 is a cross-sectional view of a state in which a predetermined photoresist is formed on an insulating film. FIG. 4 is a cross-sectional view of a manufacturing method of a semiconductor device according to an embodiment of the present invention.
(I) Cross-sectional view showing a state where a second selective opening smaller than the first selective opening is formed in an insulating film. (J) Cross-sectional view showing an electrode made of aluminum and an electrode formed on the back surface of the substrate. 5 Cross-sectional view of a conventional semiconductor device chip structure
REFERENCE SIGNS LIST 1 N-type silicon substrate 2 P-type diffusion layer 3 silicon dioxide film 4 a insulating film 4 b insulating film 4 c insulating film 5 metal electrode 6 selective opening 6 a first selective opening 6 b second selective opening 7 backside electrode 8 photoresist

Claims (3)

An insulating film for partitioning a semiconductor element region selectively provided on a semiconductor substrate, a high impurity concentration diffusion layer provided in the semiconductor element region, a selective opening provided on the diffusion layer, In a semiconductor device having an electrode structure including a metal electrode selectively provided on a selective opening, the insulating film is an insulating film composed of a stack of two or more different insulating films, A semiconductor device, wherein a stacked insulating film covers a side surface of the insulating film on a selective opening side and reaches the diffusion layer having a high impurity concentration. 2. The semiconductor device according to claim 1, wherein, in an insulating film formed by laminating two or more different insulating films, a side surface of the insulating film on a selective opening side is stacked in a stepped shape. A step of selectively forming an insulating film for partitioning a semiconductor element region on a semiconductor substrate, a step of forming a diffusion layer having a high impurity concentration in the semiconductor element region, and forming various insulating films on the semiconductor element region Forming a first selective opening reaching the high impurity concentration diffusion layer in the insulating film; and forming a single insulating layer covering the entire surface of the semiconductor element region including the first selective opening. Forming a film; forming a second selective opening smaller than the first selective opening reaching the high impurity concentration diffusion layer; and forming the high impurity concentration through the second selective opening. Forming a metal electrode reaching the diffusion layer of (1).

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