JPS63246831A - Silicon crystal substrate - Google Patents

Abstract

PURPOSE:To form a silicon substrate, which is hardly affected by oxygen in the substrate, carbon density and the like, by implanting at least one kind of ion, which is selected from among the oxygen and the carbon, at high energy into the inside of the substrate from the main surface of the silicon single crystal substrate at first, and using the first ion implanted layer as a nucleus for defect gettering. CONSTITUTION:Oxygen ions are implanted into the main surface of an Si substrate 1 at high energy at 500 keV or more. A first implanted layer 2, which has a density peak Np at a depth Dp of several mum, is formed. At least the peak density Np is selected higher than the density Nso of the oxygen, which is included in the substrate 1 in the conventional method. Then, a defect forming nucleus such as a lamination defect is yielded in the first implanted layer 2 in a heat treatment step. Defects around the nucleus are absorbed. A non-defect layer 3 is formed on the surface side of the substrate 1. Since the defect absorbing layer can be formed at an accurate position positively, the reproducibility of the manufacturing yield of the semiconductor devices can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to silicon crystal substrates for manufacturing semiconductor devices.

[Summary of the Invention] A silicon substrate is provided in which oxygen ions are implanted to a depth of several μI using a high-energy ion implanter, and the implanted layer serves as a defect absorbing layer in a semiconductor device manufacturing process.

[Prior art] With the advancement of high performance and high manufacturing yield of semiconductor taste devices,
Higher quality silicon substrates are desired.

For this reason, intrinsic gettering, etc., is performed to generate and absorb defects inside the crystal through a complicated heat treatment process, and to reduce the number of defects near the surface. However, this phenomenon has problems with reproducibility because it depends on the oxygen and carbon density in the substrate.
Also, the board holder required careful inspection when inserted.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems, and provides a silicon substrate that is less affected by oxygen, carbon density, etc. in the substrate.

[Means for Solving the Problems] A silicon substrate according to the present invention is manufactured by implanting at least one ion of oxygen or an RFC element in a few microns using a high-energy ion implanter.
m's music; it is something that is controlled by the master.

[Function] Normally, silicon substrates contain oxygen at 5~loxloI7cm-
Even if 3° carbon is included on the order of 1015 cm-3.

For example, if oxygen ions are implanted at a peak density higher than the above density, this implanted layer will serve as a defect absorbing layer in the heat treatment step of the manufacturing process. The thickness of the so-called denuded zone can be controlled almost arbitrarily by controlling the implantation energy.

[Example] The present invention will be explained in detail below using the drawings.

(1) Example 1 (FIGS. 1 to 3) FIG. 1 shows a schematic cross section of a silicon substrate 1 of the present invention. As shown in the density distribution in Fig. 3, oxygen ions are implanted into the main surface of a 51 substrate l with high energy using 500 keys or more to form a first implanted layer 2 having a density peak Nρ at a depth Op of several μm. It is. at least peak density Np
is selected to be higher than the oxygen density Nso contained in the conventional substrate l. For example, IMeV, IxlO 14cm-2 is implanted and Np+:g 5xlO"cm-3 is implanted to a depth Dp-1,
Formed to 5 μm.

Figure 2 shows that defect formation nuclei such as stacking faults are generated in the first injection layer 2 during the heat treatment step of the manufacturing process, absorb surrounding defects, and form a base 4.
It is a schematic diagram in which a defect-free layer 3 is formed on the surface (toward) of Fit. The location of defect forming nuclei is controlled by the implantation energy. Although the example of oxygen has been described, the same applies to carbon or oxygen and ten carbons.

(2) Example 2 (FIG. 4) FIG. 4 shows the density distribution in which the first ion implantation of oxygen and the second ion implantation of 51 were performed shallower than the first implantation layer. Since many vacancies and interstitial atoms are generated by the second implantation of Sl, the first implantation layer more reliably becomes a defect nucleus. Furthermore, since the crystal layer shallower than the first injection layer undergoes a recrystallization process, its crystallinity becomes better.

[Effects of the Invention] As described above, according to the present invention, the defect absorption layer can be reliably formed at an accurate position, so that the reproducibility of the manufacturing yield of semiconductor devices can be improved. In the above example, it has been described that ion implantation is performed over the entire surface of the substrate, but it is also possible to perform ion implantation selectively if necessary.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the 51 substrate according to the present invention, Fig. 2 is a cross-sectional view of the Si substrate of the present invention after heat treatment, Fig. 3 is an oxygen density distribution diagram of Fig. 1, and Fig. 4 is a cross-sectional view of the Si substrate of the present invention after heat treatment. FIG. 7 is an oxygen and Sl density distribution diagram showing another example. 1----5i substrate 2-m-first ion implantation Pi3--
−Defect-free layer

Claims (2)

[Claims] (1) At least one type of ion selected from oxygen and carbon is first ion-implanted from the main surface of a silicon single crystal substrate into the substrate at a high energy of 500 keV or more, and the first ion-implanted layer is used as a defect getter. A silicon crystal substrate characterized by being the nucleus of a ring. (2) The silicon crystal substrate according to claim 1, wherein the second ion implantation of silicon is performed at a depth shallower than the first ion implantation layer.