JPH03217019A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of surface defects of a semiconductor substrate and to manufacture a semiconductor device having excellent reliability without deterioration in characteristics by performing preheating for the semiconductor substrate which is damaged by ion implantation and the like under a pressure reduced or inactive-gas atmosphere, heating the substrate under an oxidizing gas atmosphere, and forming an oxide film. CONSTITUTION:Preheating is performed for a semiconductor substrate 1 which is damaged by ion implantation or plasma treatment in a pressure reduced or inactive-gas atmosphere. Then, the substrate is heated in an oxidizing gas atmosphere. Thus, an oxide film 8 is formed. For example, boron ions 4 are made to irradiate with an SiN film 3 as a mask, and the ions are implanted into the silicon substrate 1. Then a damaged layer 5 is formed in the silicon substrate 1 by the introduction of the ions. Then, the silicon substrate undergoes preliminary annealing in a diffusing furnace in an N2 atmosphere at 900 deg.C for 60 minutes. Thus the damaged layer 5 is recovered to a certain extent and converted into a damage recovered layer 6. Then, oxidation is performed for the silicon substrate at 1,100 deg.C for 100 minutes by a LOCOS method. Thus, an oxide film 8 having the thickness of 9,000Angstrom and a channel-stopper diffused layer 7 is formed.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a method for manufacturing a semiconductor device.

More specifically, the present invention relates to improvements in the oxide film forming process.

(Example) Conventional technology In a conventional semiconductor device, a SiOy film 12 and a SiN film are sequentially formed on a silicon substrate 11 as shown in FIG. The SiN film is etched in the area where it is intended to be formed, and then the area shown in Fig. 2 (
As shown in B), there is a PN under the element isolation region in this region.
In order to prevent inversion (channel stopper), impurity ions I4 are irradiated and implanted into the semiconductor (as a result, a damaged layer I5 is formed in the semiconductor substrate), and then a high temperature and long oxidation treatment is performed. Then, an oxide film (element isolation region) +6 was formed as shown in FIG. 2(C). However, 17 is a channel stopper diffusion layer, l8
is a dislocation portion, and 19 is an OSF (stacking fault induced in an oxidizing atmosphere).

(c) Problems to be Solved by the Invention In the above-mentioned conventional method for manufacturing semiconductor devices, as miniaturization progresses, the reduction in impurity concentration on the semiconductor substrate surface due to the two-dimensional diffusion of the channel stopper cannot be ignored, and the channel This increases the amount of impurity implanted into the stopper, and if this amount exceeds a certain amount, defects will occur on the surface of the semiconductor substrate during the oxidation process. Among the surface defects of semiconductor substrates, dislocations in particular repeatedly move, multiply, and grow in the semiconductor substrate, and once they are formed, they are difficult to remove and have a very large impact on device characteristics. There is a problem of deterioration.

This invention was made to solve the above problem, and is capable of suppressing the occurrence of surface defects (crystal defects) on the semiconductor substrate during the oxidation process of the semiconductor substrate, thereby improving reliability without deteriorating the characteristics. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can manufacture an excellent semiconductor device.

(2) Means for Solving the Problem The inventor has proposed a method for forming an oxide film by thermal oxidation on a semiconductor substrate processed by ion implantation or plasma processing without generating surface defects (crystal defects). After extensive research, we found that on the surface and inside of semiconductor substrates processed by ion implantation or plasma processing,
For example, the fact that a damaged layer is formed as an aggregation of point defects such as recoil St (silicon atoms arranged deviated from the silicon crystal lattice) and vacancies, The fact that this damaged layer can be recovered to some extent when heated under an active gas atmosphere;
And this damaged layer is recovered to some extent.Even if the restored base slope is heated in an oxidizing gas atmosphere, the OSF remains
This invention was achieved by discovering the fact that defects such as dislocations are not induced.

According to this invention, an oxide film is formed by preheating a semiconductor substrate damaged by ion implantation or plasma treatment under reduced pressure or an inert gas atmosphere, and then heating it under an oxidizing gas atmosphere. A method for manufacturing a semiconductor device is provided.

The above preheating is for recovering damage to the semiconductor substrate caused by ion implantation or plasma treatment, and the semiconductor substrate damaged by ion implantation or plasma treatment is heated under reduced pressure or in an inert gas atmosphere. Usually 70
It can be carried out by heating to 0 to 1000°C.

The above-mentioned ion implantation or plasma treatment is for processing a semiconductor substrate, and includes, for example, processing such as implantation of impurity ions into the semiconductor substrate and dry etching.

Damage to the semiconductor substrate (i.e., crystal defects that occur on the surface and inside of the semiconductor substrate due to ion implantation or plasma treatment, such as recoil St, vacancy points, and other point defect aggregations) can.

The above-mentioned reduced pressure can be generally 1 to 10 Torr or less.

The inert gas atmosphere may be, for example, nitrogen, gas, argon gas, or the like.

In this invention, an oxide film is formed on the semiconductor substrate by subsequently heating it in an oxidizing gas atmosphere.

The oxidizing gas atmosphere may be, for example, oxygen gas, air, nitrogen dioxide gas, or the like. The above heating can be normally performed at 800 to 1200°C.

Examples of the oxide film include an oxide film for forming an element isolation region formed by the Locos method, a gate oxide film, and the like.

Further, the process can be shortened by forming the oxide film in the same sequence following the preheating described above.

(e) Effect Preheating under reduced pressure or an inert gas atmosphere recovers damage to the semiconductor substrate caused by ion implantation or plasma treatment, and prevents the occurrence of crystal defects such as OSFs and dislocations in the subsequent oxide film formation process. prevent.

(f) Example Embodiments of the invention will be described with reference to the drawings.

First, as shown in FIG. 1(A), a 600-layer thick SiS film 2 is formed on a silicon substrate 1 by a thermal oxidation method, and then a 2500-layer thick SiN film 2 is formed on this by a CVD method.
Stack the membranes. Next, the surface layers of the SiN film 3 and the SiOz film 2 in the region where an oxide film (element isolation region) is intended to be formed by the LOCOS method are removed.

Next, as shown in FIG. 1(B), boron ions 4 are irradiated to implant ions into the silicon substrate l.

At this time, as the implanted ions are introduced, a damaged layer 5 is formed in the silicon substrate l as a collection of point defects such as recoil St and vacancy points.

Next, this silicon substrate is subjected to preliminary annealing treatment at 900° C. for 60 minutes in a diffusion furnace in an N atmosphere. As a result, the damaged layer 5 is recovered to some extent and converted into a loss recovery layer 6.

Next, this silicon substrate was subjected to an oxidation treatment using a coating method at 1100° C. for 100 minutes, resulting in a film thickness of 9000° C. as shown in FIG. 1(D). An oxide film 8 of t is formed. Note that 7 is a channel stopper diffusion layer, and no crystal defects were observed under the oxide film 8.

After this, elements are formed on this silicon substrate l to produce a semiconductor device.

The obtained semiconductor device had no deterioration in characteristics and was superior in reliability, compared to a semiconductor device manufactured in the same manner as in this example without performing the preheating treatment, which had a junction leak defect. Ta.

(G) Effects of the Invention According to this invention, defects on the surface of a semiconductor substrate caused by ion implantation or plasma treatment can be removed, and the generation of crystal defects in the subsequent oxidation process can be suppressed, without deterioration of characteristics. A method for manufacturing a semiconductor device that can manufacture a semiconductor device with excellent reliability can be provided.

[Brief explanation of drawings]

7. FIG. 1 is an explanatory diagram of the manufacturing process of a semiconductor device manufactured in an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the manufacturing process of a conventional semiconductor device. 1...Silicon substrate, 2...SiOz film, 3...SiN film, 4...Boron ion, 5...Damaged layer, 6... ...damage recovery layer,
7... Diffusion layer of channel stopper, 8...
...Oxide film by Locos method. 18-μ)

Claims (1)

[Claims] 1. An oxide film is formed by preheating a semiconductor substrate damaged by ion implantation or plasma treatment under reduced pressure or an inert gas atmosphere, and then heating it under an oxidizing gas atmosphere. A method for manufacturing a semiconductor device.