JPS59188925A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance mechanical strength of a substrate, and to contrive to stabilize the manufacturing process of a semiconductor device by a method wherein carbon ions having high energy of the prescribed value or more are implanted for formation of oxygen depositing nuclei in the substrate to provide oxygen deposited layers to depend upon carbon distributing concentration. CONSTITUTION:A substrate 1 having the degree of 4X10<17>cm<-3> of interlattice oxygen concentration and the degree of 1-3X10<15>cm<-3> of carbon concentration in a crystal, and distributed inside uniformly together with oxygen 2 and carbon is prepared. Then high energy carbon implantation is performed, implantation of carbon atoms 11 is performed by 4MeV, 5X10<13>cm<-3>, peak concentration thereof is the degree of 1X10<18>cm<-3>, the peak exists at the distance of the degree of 5mum from the surface, half-width is 0.2mum, and a buried type carbon implanted layer is formed. Moreover when heat treatment is performed at 1,200 deg.C for the degree of two hours, the implanted carbons act as oxygen depositing nuclei to form buried type oxygen deposited layers (defect layers) according to oxygen deposits, and complete crystal regions 13 having lower oxygen concentration at the shallower region and at the region deeper than the carbon implanted layer, and having the extremely small amount of defects are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a semiconductor device, and particularly relates to complete crystallization of an active layer of a semiconductor substrate, and is applied to high-density integrated circuits.

[Background technology of the invention]

Conventionally, the indolithic gettering (IQ) method, the back surface defect method, and the like have been mainly used as means for completely crystallizing the active layer of a semiconductor substrate.

As shown in Figures 1 to 3, the above IG method first involves the following steps:
Crystalline silicon substrate with oxygen content higher than solid solubility (1)
(hereinafter abbreviated as substrate) is prepared (Fig. 1).

Note that (2) in the figure indicates oxygen present in the substrate. Next, a first stage heat treatment for a long time at a low temperature is performed at 700°C for 48 hours, and oxygen precipitates (3) which become defects in the substrate are formed.
(Figure 2). Next, a second stage heat treatment at a high temperature and a long period of time is performed at, for example, 1100° C. for 4 hours to drive out oxygen from the substrate surface and form a perfectly crystalline layer (4) on the surface layer (FIG. 3).

In a substrate subjected to the tilted IG process, heavy metals that have undesirably entered the substrate in subsequent steps are gettered to defects inside the substrate, so that a perfectly crystalline layer can be preserved.

In the next backside defect method, impurities that generate defects are introduced mechanically or by diffusion from the backside of the substrate.
) is used as a gettering site (Figure 4)
.

[Problems with background technology]

The IG-treated semiconductor substrate has a defective layer containing high-density oxygen precipitates except for a thin layer on the surface, and has extremely low mechanical strength. For this reason, cracking and chipping occur frequently during the substrate processing process, significantly reducing product yield. I.G.
The oxygen concentration in the substrate after processing follows a distribution in the form of a complementary error function, as seen in the oxygen concentration distribution diagram shown in FIG. The depth of this distribution varies depending on the second stage heat treatment time of the IG treatment and the thermal history after the IG treatment. Furthermore, when a deep element is formed, the oxygen concentration near the junction is high, which adversely affects the characteristics of the υ element. In order to prevent this, it is necessary to perform a second stage heat treatment for an extremely long time.

Unlike the IG method, the back surface defect method does not perform nucleation, but instead utilizes the Gerakling effect caused by the introduced defects, and has the drawback that the heat treatment performed after introducing the defects recovers the defects, making it impossible to obtain a sufficient effect. be.

[Purpose of the invention]

In order to improve the above-mentioned conventional drawbacks, this invention has been developed to manufacture a semiconductor device with the aim of stabilizing a semiconductor integrated circuit using an IG processing method that maintains sufficient mechanical strength and is thermally stable. provide a method.

[Summary of the invention]

This invention implants high-energy carbon ions into a semiconductor substrate to form an oxygen precipitated layer depending on the implanted carbon distribution concentration, and uses this as a gettering site to form a perfectly crystalline layer with a stable and low oxygen concentration on the surface layer.

[Embodiments of the invention]

Next, one embodiment of the present invention will be explained in detail with reference to the drawings. First, a substrate ('1) is prepared (Fig. 1). The interstitial oxygen concentration in the crystal of this substrate (1) is about 4 x 1017 crn-3, which is lower than that of ordinary IG crystals, and the carbon concentration is about 1 to 3 x IQ" cm-2. The distribution in the substrate is shown in Figure 8, where the oxygen concentration is indicated by the line (0),
Further, the concentration of carbon is shown by a line (C). In such an initial state, both oxygen and carbon are uniformly distributed within the substrate.

Next, FIG. 6 shows the state after high-energy carbon ion implantation. In the figure, aυ is the implanted carbon atom, and the implantation was performed at 4 Men, 5 × 10" α-2. The peak concentration was about l x IQ "m-", and the implantation peak was about 51 tm rotation from the surface. However, the half width is about 0.2 μm, and it can be seen that a buried carbon injection layer is formed as shown in FIG. 9 using the same representation as FIG. 8.

Next, heat treatment was performed at 1200°C for about 2 hours, and as shown in Figure 7, the implanted carbon became oxygen nucleates and oxygen precipitates (12+) formed a buried oxygen precipitate layer (defect layer). A perfectly crystalline region (2) is formed, which is a region shallower and deeper than the carbon implanted layer, where the oxygen concentration is lower and the amount of defects is extremely small.Furthermore, the above is shown in FIG. The effect of carbon injection is clearly seen from the distribution of oxygen in the initial state shown by the broken line in the figure.

That is, due to the upward slope, the oxygen precipitated layer is extremely stable because its core is carbon, which has a small diffusion constant, and effectively acts as a getter site for heavy metal ions and the like.

[Effects of the invention]- According to this invention, the conventional IG substrate and the foreign potassium high concentration defect layer are made into an extremely thin buried layer of about 0.5 μm, so mechanical strength is high and accidents such as cracks in the process are avoided. decreased.

Next, since it has thermally stable oxygen precipitation nuclei, the perfect crystal layer on the surface of the substrate is extremely stable, and the oxygen concentration in the perfect crystal layer can be lowered as shown in FIG. 11.

In the figure, the relationship with the additional heat treatment temperature is shown by a broken line. Further, the correlation with the depth from the substrate surface is shown in FIG. 12 in comparison with the conventional method (indicated by a broken line). Further up the slope is the first
As shown in FIG. 3, it is clear that this is due to the fact that the oxygen concentration in the starting substrate could be reduced by forming oxygen precipitation nuclei by ion implantation.

Next, in the conventional IG method, long-term low-temperature heat treatment was required to form oxygen precipitate nuclei, but by using this invention, only the second stage heat treatment at high temperature is required, which improves productivity. There are also notable improvements.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the substrate, Figs. 2 and 3 are cross-sectional views of the substrate during the process using the conventional IG method, Fig. 4 is a cross-sectional view of the substrate using the back side defect method, and Fig. 5 is the substrate. 6 and 7 are cross-sectional views of the substrate during the process according to the manufacturing method of the first embodiment, and FIG. 8 is a diagram showing the oxygen concentration distribution in the substrate.
Figure 9 is a diagram showing the concentration of oxygen and carbon in the substrate in the state shown in Figure 6. Figure 10 is a diagram showing the concentration of oxygen and carbon in the substrate in the state shown in Figure 6. A diagram showing the concentration of oxygen and carbon in the substrate of the substrate in the state shown in Figure 7, and Figure 11 A diagram showing the change in oxygen concentration in the perfect crystal region due to heat treatment performed after FiIG compared with the conventional one. , FIG. 12 is a diagram showing the oxygen concentration in the IG substrate in the depth direction, and FIG. 13 is a diagram showing the change in the amount of precipitated oxygen with respect to the oxygen concentration in the crystal in the oxygen precipitated region. 1 Substrate 2 Oxygen in the substrate 4 Perfectly crystalline layer 11 Injected carbon atoms 12 Oxygen precipitates 13, Perfectly crystalline region Representative Patent attorney Mr. Inoue 1 Figure 2 Cause 5 Figure 6 Figure 7 Figure 8 7 Ha No. 9 Figure Tiger, ~- Figure 10 Figure 1 Figure 12 Figure 13 Le Shapeng + Transport -

Claims (1)

[Claims] JIMeV teaches a method for manufacturing a semiconductor device that precipitates oxygen existing inside a semiconductor substrate and uses it as a gettering site, and is used to form oxygen precipitate nuclei in a semiconductor substrate.
A method of manufacturing a semiconductor device characterized by performing high-energy carbon ion implantation and providing an oxygen precipitated layer depending on the implanted carbon distribution concentration.