JPS63120430A - Method for preventing occurrence of crystal defect - Google Patents

Abstract

PURPOSE:To unnecessitate the performance of a strict control over an Si single crystal substrate as performed on IG effect without extinguishing the gettering effect such as the distortion on the back side of the substrate by a heat treatment by a method wherein the heavy metal contaminant and the like on the active region of a device is gettered by generating a crystal defect on an element isolation region. CONSTITUTION:The heavy metal contaminant and the like is gettered by generating the crystal defect 8 on an element isolation region 3. For example, an N-type diffusion region 4 is formed on a P-type Si single crystal substrate 1 using an oxidation photo- lithographic method. Then, the isolation region 3 of each element is provided by removing the oxide film 2 using a photo-lithographic method, and boron 5 is ion-implanted as the impurities for element isolation. Subsequently, when the element isolation impurity boron 5 is pressed in using a wet oxidation method at 114 deg.C for 90 minutes for the purpose of pushing-in of the element isolation impurity boron 5 into the Si single crystal substrate 1, a crystal defect is generated on the element isolation region 3. Then, when an N-type epitaxial layer 7 is formed on the substrate 1, said crystal defect is turned into nuclei on the element isolation region 3, and a crystal defect 8 is formed in the epitaxial layer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing crystal defect generation by gettering contaminants such as heavy metals from a device active region.

[Conventional technology]

Conventionally, this type of gettering method involves introducing strain into the back surface of a single crystal substrate to getter away heavy metals and the like in the device active region. In addition, in the case of SI single crystal substrates, a so-called intrinsic getter (intrinsic getter) is used to precipitate oxygen in the 8i single crystal substrate and get heavy metal contaminants in the device active region by strain between the precipitates and the bulk 8i. (hereinafter referred to as the IG effect).

[Problem that the invention seeks to solve]

The above-described conventional gettering method has the disadvantage that the strain introduced by the heat treatment during device manufacturing disappears due to the strain on the back surface of the single crystal substrate, and the gettering effect cannot be maintained until the final step of the device manufacturing process. Moreover, in the IG effect, depending on the heat treatment in the device manufacturing process and the oxygen concentration in the single crystal substrate, crystal defects may occur in the device active region, resulting in a decrease in device yield. Therefore, it is necessary to strictly control the oxygen concentration of the single crystal substrate, which is not practical in various devices manufactured by combining various heat treatments.

[Means for solving problems]

The crystal defect prevention method of the present invention includes selectively generating crystal defects in the element isolation region in the step of forming the element isolation region to getter heavy metal contaminants, etc. in the device active region.KJ:,! l) Preventing the occurrence of crystal defects in the device active region.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

An N-type diffusion region 4 is formed on a P-type Sl single crystal substrate 1 by oxidation photolithography. Next, the oxide film 2 is removed by photolithography, isolation regions 3 are provided for each element, and boron 5 is added as an impurity for element isolation at 7 QKeV.
5 x l Ql' and -2 ions are implanted (see Figure 1 (a)
)) When the element isolation impurity boron 5 is forced into the 8i crystal substrate 1 by wet oxidation at 1.140° C. for 90 minutes, crystal defects are generated in the element isolation region 3.

Next, an N-type epitaxial layer 1-7 is formed on the single crystal substrate 1 by a normal epitaxial growth process. At that time, the crystal defects become nuclei in the element isolation region 3, and crystal defects 8 are formed in the epitaxial layer 7 (FIG. 1(b)).
If a transistor is subsequently manufactured based on the normal NPNTr manufacturing process, the heavy metal contaminants mixed in during those processes will be gettered by the strain field of the crystal defect 8, and the device active region will be free of contaminants, and the device Yield is improved.

FIG. 2 is a longitudinal sectional view of Example 2 of the present invention.

An N-type epitaxial layer 17 is grown on a P-type nested crystal substrate 1 having an N-type buried layer 4, and an oxide film 2 is formed by thermal oxidation.
After forming the multi-element isolation region 3 by photolithography, Si is implanted in 5 Q KeV l x l Q14) to form an 8i ion implantation layer 9 (FIG. 2(a)).
. Next, boron is thermally diffused into the element isolation region 3 at 1000°C to form an element isolation boron layer 1o.

At this time, the ion-implanted S1 layer 9 becomes excessive in the S1 single crystal, so crystal defects 8 are formed (Fig. 2(b)
)) If a transistor is manufactured based on the normal NPNTr manufacturing process, contaminants such as heavy metals are gettered by the crystal defects 8, and the yield of device characteristics 2 is improved.

〔Effect of the invention〕

As explained above, the present invention has the effect of gettering heavy metal contaminants in the device active region by introducing crystal defects in the cord separation region, and also has the effect of gettering heavy metal contaminants in the device active region. It does not disappear like the backside bundle, and there is no need to strictly control the S + IP crystal substrate like the ■G effect.

[Brief explanation of the drawing]

Figure 1 (aThllllB figure (a), (b) fd book % bright o
FIG. 2 is a cross-sectional view of a process for introducing crystal defects into an element-1m region. DESCRIPTION OF SYMBOLS 1... Si single crystal substrate, 2... Oxide film, 3... Element isolation region, 4... N-type buried diffusion layer, 5... ...Ion-implanted boron layer, 6...
...Buried boron layer, 7. Old... N-type epitaxial layer, 8... Crystal defects in element isolation region in epitaxial layer, 9. Old... Ion implantation 81#, 10...・
...7 layers of diffusion boros for element isolation. spear 1 concave

Claims (1)

[Claims] A method for preventing crystal defects, characterized in that heavy metal contaminants, etc. in a device active region are gettered by generating crystal defects in an element isolation region.