JPS6084831A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable formation of U-shaped grooves on a semiconductor substrate with good reproductivity and controllability for microminiaturization of element separation region by forming impurity implantation layers in the predetermined depth from a surface of a semiconductor substrate and grooves which reach the impurity implantation layers from the surface of the semiconductor substrate. CONSTITUTION:On an Si substrate 1, a necessary pattern consisting of photoresist 2 is formed and oxygen ions are implanted by ion implantation using said photoresist 2 as a mask. As a result, O<+> implantation layers 3 consisting of SiOx are formed in the region of the predetermined depth. After that, the Si substrate 1 is subjected to anisotropic etching by dry etching using a gas consisting of a chlorine group gas mainly and U-shaped grooves 4 are formed. As a ratio of etching speed of the SiOx layer and Si is larger than 10, depths of the U-shaped grooves 4 are determined by depths of the impurity layers 3 formed by ion implantation and the uniformity is improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a semiconductor device, and in particular, to a method for manufacturing a semiconductor device, in particular for forming an element isolation region (field region) that determines the active area of an integrated semiconductor device. This relates to the formation of grooves.

(Conventional example: 鑵空, L-Mo's dark neck) As the integration of semiconductor devices progresses, in the process of separating the active region and field region, the so-called element isolation process, a portion corresponding to the element isolation region of the semiconductor substrate is used. A commonly used method is to form a U-shaped groove. Dry etching, typically reactive ion etching, is used to form U-shaped grooves, but the depth of the grooves varies due to non-uniformity of the etching rate within the wafer.
It has been difficult to stably form grooves of a predetermined depth.

(Objective of the Invention) An object of the present invention is to form a U-shaped groove in a semiconductor substrate with good reproducibility and controllability in order to miniaturize element isolation regions.

(Structure of the Invention) The present invention involves selectively forming a film dulling material layer by ion implantation at a predetermined depth at a location corresponding to an element isolation region of a semiconductor substrate, and then performing an etching process to form the film at a predetermined depth. A trench is formed to the depth of the impurity layer.

In this case, the etching speed of the impurity layer formed by ion implantation is less than a fraction of the etching speed of the semiconductor substrate, so the etching of the semiconductor substrate is
It also stops at the impurity layer. According to the present invention, the depth of the U-shaped groove formed in the semiconductor substrate is determined by the depth of the impurity layer formed by ion implantation, and its uniformity is improved.

(Explanation of Examples) Examples will be described below based on the drawings.

FIG. 1 shows an embodiment of the present invention. First, as shown in FIG. 1(a), a required pattern consisting of one photoresist 2 is formed on a silicon substrate 1, and this photoresist 2 is Using as a mask, oxygen ions (0+) are implanted into the silicon substrate 1 at 15oKev by ion implantation method. In this example, the dose H1,2X 101815
I did it. The glojection range at this time (Rp
) has a reed of about 04 μm, and as a result, a 0+ injection skin 3 made of SiOx (X≧2) is formed in the region at the depth of the reed, as shown in FIG. 1(b). Thereafter, using the photoresist 2 as a mask, the silicon substrate 1 is anisotropically etched by dry etching using a gas containing chlorine gas as the main component, resulting in a 0-shape as shown in FIG. 1(C). Groove 4 was obtained. Under the etching conditions of this example,
The etching rate ratio between the SiOx layer formed by ion implantation and Si is 10 (Si/SiOx).

Further, the uniformity of the Si etching rate under these etching conditions is ±5% within the wafer.

Figure 2 shows the variation in the depth of the grooves in the wafer when U-shaped grooves are formed in a silicon substrate by the conventional method and by the method of the present invention under the etching conditions of this example. It is. According to this, it can be seen that the variation according to the method of the present invention is 1/10 or less compared to that of the conventional method, and is so small that it falls within the measurement error range.

In this embodiment, oxygen was used as the impurity to be ion-implanted, but other impurities such as nitrogen may also be used.

(Effects of the Invention) As explained above, according to the present invention, the depth of the groove formed in the semiconductor substrate is controlled by ion implantation without depending on the variation in the etching rate, so that the variation is reduced. It becomes extremely small, and uniformity and stability of the process can be obtained, and the quality of the semiconductor device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the manufacturing process of an embodiment of the present invention;
FIG. 2 is a diagram comparing the variation in depth of U-shaped grooves obtained by the conventional method and the method of the present invention. 1 ・・・・・・・・・7 Recon board, 2 ・Curved surface
Photoresist, 3...0 Injection layer, 4
・・・・・・・・・U-shaped groove. Patent applicant: Matsushita Electronics Co., Ltd. Agent: Hisashi Hoshino. Figure 1 (0) Figure 2

Claims (2)

[Claims] (1) selectively implanting impurity ions into a semiconductor substrate to form an impurity implantation layer at a predetermined depth from the surface of the semiconductor substrate;
A method of manufacturing a semiconductor device, comprising the step of forming a trench that reaches the impurity injection layer. (2) Claim 1 (1) characterized in that oxygen or nitrogen is used as the impurity to be ion-implanted.
) The method for manufacturing a semiconductor device according to item 2.