JPS5830144A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the rate of yeild by a method wherein an electrically inactive region on a semiconductor substrate surface undergoes ion implantation, or heat treatment in a high temperature N2 environment, to form an epitaxial layer and the crystal defects therein absorb defects in an active region. CONSTITUTION:As ions are diffused into the (111) plane of a p type Si layer 21 for the formation of a buried n layer 22, and an SiO2 layer 23 is provided with an opening to accept diffused B ions for the formation of an isolating layer 25. Next, the layer 25 is implanted with Ar ions, or the substrate 21 is treated in a 1,200 deg.C N2 environment for approximately 5hr, for the formation of a crystal defect regions 26 on the surface of the layer 25. The SiO2 layer 23 is then removed, and another crystal defect region 28 is produced on the region 26 when an n epitaxial layer 27 is formed by using SiH4. An SiO2 layer 29 is provided with an opening 30, whereinto B ions are diffused for the formation of an isolating layer 31, when B ions go out of the region 28. After this, diffusion and heat treatment are performed on the region 27' for the formation of a collector, base, and emitter, when the crystal defects produced in the process is absorbed by the region 28, which allows the region 27' to be free of crystal defects. With crystal defects not in existence in the junction surfaces between the regions 27' and the isolating layers 25 and 31, there is no fall in the withstand voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device that can prevent a decrease in yield due to crystal defects.

Conventionally, in the manufacturing process of semiconductor devices, crystal defects that exist in electrically active regions lead to deterioration of device characteristics.
This caused a decrease in yield. In other words, minute crystal defects in the active region shorten the lifetime of minority carriers.
The device characteristics are deteriorated by increasing the leakage current of the p-n junction. For example, in a bipolar semiconductor device, a leakage current between an emitter and a collector due to an emitter pipe or a leakage current between an emitter and a base causes a reduction in the current amplification factor (referred to as hyx).

Even in MO8 type semiconductor devices, crystal defects have an adverse effect such as a decrease in mutual conductance due to IJ current, causing a decrease in yield. On the other hand, as the dimensions of elements in semiconductor integrated circuits have recently become smaller and the number of elements constituting semiconductor integrated circuits has increased, small crystal defects have a large impact on element characteristics and the yield of integrated circuits. give.

In order to prevent the occurrence of such crystal defects, conventional techniques have involved mechanically damaging the backside of the semiconductor substrate or introducing high-concentration impurities to prevent contamination near the surface of the substrate.
Since this is done at an early stage in the manufacturing process, complex heat treatments are performed many times after this. However, when subjected to such repeated heat treatment, the effect of back surface treatment is halved.

Furthermore, in order to prevent impurities introduced into the back surface of the substrate from reevaporating during high-temperature heat treatment and contaminating the surface of the substrate, a special process must be added. Next, a method of forming an element isolation region by conventional ion implantation will be explained with reference to FIG.

Semiconductor substrate (p-type, specific resistance 10-20 Ωcm).

(111) with a surface index of 11, the sheet resistance is about 80
An n-type buried region 12 of Ω/hole is formed by an arsenic spin-on diffusion method.

Next, a first oxide film 13 is formed on the semiconductor substrate 11, a first opening 14 is provided for diffusion into the element isolation region, and a high concentration (10 to 10 10
Diffusion of boron of Δm) and sheet resistance of 60 to 100
A first isolation region 15 of jQlo is formed. At this time, a first crystal defect region 16 is formed inside the first isolation region 15 due to ion implantation damage. (Figure 1a)
. Next, the first oxide film 13. removed and heated to 1050℃
An n-type epitaxial layer 17 with a thickness of about 4 μm and a specific resistance of 1 Ω-CIIl is formed by an epitaxial method using SiH4. At this time, due to the influence of the first crystal defect region 16, crystal defects occur in the epitaxial layer 17 on the first crystal defect region 16, and a second crystal defect region 18 is formed. (Fig. 1b) However, in the above method, in order to form the first crystal defect region 16, it is necessary to implant boron at a high concentration of 15 16 10 to 10 ion implantation conditions. However, when boron is diffused at a high concentration, auto-drainage of boron occurs when the epitaxial layer 17 is formed, making it difficult to control the resistivity of the epitaxial layer.

The present invention eliminates these conventional drawbacks and uses ion implantation or heat treatment in an electrically inactive region on the surface of a semiconductor substrate in a nitrogen atmosphere at 1000°C to 1200°C to epitaxially grow a Si film. The purpose of this is to absorb crystal defects in the active region into the inactive region and improve the yield in the manufacturing process of semiconductor devices.

The present invention attempts to absorb crystal defects in an electrically active region of a semiconductor surface by crystal defects generated in an epitaxially grown St film in an inactive region.

As the inactive region, an element isolation region of a bipolar integrated circuit, a field region of an MO8 type integrated circuit, etc. can be used. Next, as an embodiment of the present invention, a method for providing crystal defects in the element isolation region of a bipolar integrated circuit and removing the crystal defects in the active region will be described with reference to FIG. 2A%C.

First, as shown in FIG.
1, an n-type buried region 22 with a sheet resistance of about 80Ω is formed by an arsenic spin-on diffusion method. Next, a first oxide film 23 is formed on the semiconductor substrate, a first opening 24 is provided for diffusion into the element isolation region, and the B S G
Boron is diffused using (Baron Silicate Glass) or ion implantation to form a first isolation region 25 having a sheet resistance of 400Ω, b. Next, using the first oxide film 23 as a mask, the first isolation region 25 is coated with 50 to 160 ml of silicon or the like.
With the implantation energy of Kev, the amount of impurity implanted is about 10Ω
Ion implantation is performed in the above manner to form a first crystal defect region 26 on the surface of the semiconductor substrate. Also, instead of ion implantation, the semiconductor substrate 21 is heat-treated in a high-temperature nitrogen atmosphere at 1200° C. for 4 to 6 hours to form a first crystal defect region 26 on the bare surface of the semiconductor substrate in the first isolation region 26 (
Figure 2 a).

Next, the first oxide film 23 is removed, and
By epitaxial method using iHn, the thickness of about 4
An n-type epitaxial layer with a resistivity of 1 Ω-cm is formed. At this time, due to the influence of the first crystal defect region 26, crystal defects occur in the epitaxial layer 27 on the first crystal defect region 26, and the second crystal defect region 2
8 is formed (FIG. 2b).

Next, a second oxide film 2e is formed on the epitaxial layer 17, a second opening 3o is provided for diffusion into the element isolation region, and a second isolation region of 40Ω is formed by diffusion using BSG. Form 31.

At this time, the second isolation region 31 is also diffused in the lateral direction, so that it is formed to extend outward from the second crystal defect region 28 (FIG. 1C).

After this, a collector,
When forming the base and emitter, diffusion or heat treatment is performed, and the crystal defects generated at that time are absorbed by the second crystal defects 28 to prevent the generation of crystal defects in the active region 27'. I can do it.

Moreover, since the second crystal defect region 28 is included in the first and second isolation regions 25 and 31, there are no crystal defects on the bonding surface between the active region 27' and the first and second isolation regions 25 and 31. There is no leakage current between the collector and the substrate, and the withstand voltage does not decrease.

Further, as a second embodiment, a method for reliably forming a crystal defect region inside a separation region will be described with reference to FIG.

Semiconductor substrate (p-type, specific resistance 10-2oΩ-cm).

(111) surface index) 40K, sheet resistance approximately 80
An n-type buried region 41 outside Ω is formed by an arsenic spin-on diffusion method.

Next, a first oxide film 42 is formed on the semiconductor substrate 4o, and a photoresist film 3 is further formed on the first oxide film 42.
A first opening 44 is provided at a predetermined position within the element isolation region, a predetermined distance smaller than the element isolation region (FIG. 3a).

Next, using the photoresist film 43 as an etching mask, the first oxide film 42 was over-etched using a mixed solution of HF and NH4I to make it wider than the '1st opening 44 by a predetermined distance. A second opening 46 is formed. Furthermore, using the photoresist film 43 as a mask, ion implantation is performed with an impurity implantation amount of about 10 or more at an implantation energy of 50 to 150 and @V using the photoresist film 43 as a mask. A first crystal defect region 46 is formed on the surface of the conductor substrate (FIG. 3b). Next, the photoresist film 43 is removed, a BSG film 47 is formed in the second opening 46, and heat treatment is performed. As a result, a first isolation region 48 having a sheet resistance of 400Ω7 is formed (FIG. 3C).

Next, the BSG film 47 and the first oxide film 42 are removed, and an n-type epitaxial layer 49 having a thickness of 4 μm and having a resistivity of 12 − is formed by an epitaxial method using SiH 4 at 1060° C. At this time, due to the influence of the first crystal defect region 46, crystal defects occur in the epitaxial layer 49 on the first crystal defect region 46, and a second crystal defect region 6o is formed (Fig. 3). d).

Next, a second oxide film 6 is formed on the epitaxial layer 49.
A third opening 52 is provided which is wider by a predetermined distance than the first opening 44 for diffusion into the element isolation region. By the above step of forming the second isolation region 63, the second crystal defect region 51 is included in the second isolation region 63, so that the active region 49'
There are no crystal defects on the bonding surface between the first isolation region 63 and the second isolation region 63, no leakage current occurs between the collector and the substrate, and furthermore, the withstand voltage does not decrease.

As described above, the present invention can be performed in a shorter process time than processing the back side of a substrate, and is also compared to a method in which impurities are diffused at a high concentration on the back side of the substrate and crystal defects are absorbed into the back side. Therefore, as in the present invention, absorption in the inactive region is closer to the active region in terms of distance, so the defect absorption effect is greater. Furthermore, the second crystal defect 61 was created due to crystal misalignment occurring at t9 during epitaxial growth, and even if heat treatment is repeated thereafter, it will not grow and will not have an adverse effect on the active region. , there is no increase in leakage current and no decrease in breakdown voltage. Furthermore, when defective parts are formed by implanting 51C, boron, etc. at a high concentration as in the conventional method, autodoping adversely affects the resistivity of the epitaxial layer. It does not contain ions of impurities and does not adversely affect the resistivity of the epitaxial layer. As described above, the present invention can absorb crystal defects in the active region into the inactive region, thereby improving the yield in the manufacturing process of semiconductor devices.

[Brief explanation of drawings]

FIGS. 1a and 1b are cross-sectional views of a semiconductor device for explaining a conventional isolation region forming method, and FIG. 21.40...Sl substrate, 27,49...
...Epitaxial layer, 25.48...First isolation region, 26°46...First crystal defect region, 28,51...Second crystal defect area, 31,
53...Second separation area. Name of agent: Patent attorney Toshio Nakao and 1 other person 1A
2 Figure 2 Figure easy 3 Figure 3 Figure 3

Claims (1)

[Claims] forming a first crystal defect region in a part of the main surface of a semiconductor substrate of one conductivity type; forming an epitaxial layer on the main surface of the semiconductor substrate; and forming an epitaxial layer on the first crystal defect region. a step of forming a second crystal defect region; and a step of penetrating the epitaxial layer to form an isolation region of the − conductivity type such that the second crystal defect region is included in the isolation region. Method of manufacturing the device.