JPS58100442A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form buried element isolation layers having a flat surface without using a flattening auxiliary material by a method wherein caves are formed through openings according to the nondirectional etching method, and silicon dioxide is made to accumulate thereon. CONSTITUTION:An amorphous silicon layer 2, a protective film 3 and a photo resist film 4 are formed on a single crystal silicon substrate 1, and narrow and closed groove type openings 5 are formed using the photo lithography method. Opnings 6 are formed in the protective film 3, and the caves 7 are formed in element isolation regions applying the nondirectional etching method. Silicon dioxide is made to grow in the caves 7 through the openings 6. When width of the openings 6 is about 1mum or less, the surface of the silicon dioxide layer 8 is flattened completely. The remaining amorphous silicon layer 2' is converted into the single crystal layer 2'', and the insulator layer 8 is etched to remove the projective film 3. After than, the desired semiconductor element is formed in the element forming region 2'' converted into the single crystal layer.

Description

[Detailed description of the invention] (1) Technical field of the invention The present invention relates to a method for manufacturing a semiconductor device.

(2) Prior art and problems In the prior art, a method has been proposed in which an insulator is buried in the element isolation region in order to completely isolate each element of a semiconductor device. If the width of the substrate recess is wide and exceeds 1 μm, usually only the insulator is used.
Since it is not planarized, it is necessary to use an organic material such as a resist or silicone resin as a planarizing auxiliary material. If a flattening aid made of organic matter is used, the process is added and complicated, and in addition, the sodium ion (Na'') and carbon (0
) may adhere to the substrate surface, resulting in contamination of the substrate.

Therefore, when embedding an insulator layer in a relatively wide device isolation region, we have developed a technology to form an embedded device isolation layer made of an insulator layer with a flat surface without using a flattening auxiliary material. was desired.

(3) Purpose of the Invention The purpose of the present invention is to meet such demands, and to provide a method for manufacturing a semiconductor device, which includes a step of forming a buried element isolation layer with a flat surface without using a flattening auxiliary material. Our goal is to provide the following.

(4) Structure of the Invention The structure of the present invention is to form a non-single crystal layer of silicon (81) on a single crystal layer of silicon (81) using a vapor deposition method or the like in a vacuum of 10 Torr or less. A layer, particularly an amorphous silicon (81) layer, is formed to a thickness of approximately I Am, and silicon dioxide (810,) or A protective film made of silicon nitride (81sNa) or the like and having a thickness of approximately 4000Xs is formed, and after spin-coding a photoresist or the like on it (-), a photolithography method is used to form a protective film on the element isolation region. , a narrow groove-shaped opening with a width of 1 μm or less is provided, and a non-directional etching method such as caustic potassium (t) is applied through this opening.
removing said non-monocrystalline silicon (Sl) layer, i.e., amorphous silicon (81) layer or polycrystalline silicon (Sl) layer, by applying a chemical etching method such as contacting on); forming a cavity in the element isolation region;
If necessary, silicon dioxide (white 10.) is deposited and grown until the cavity is completely filled using a method such as a method such as 1, to slightly cover the above protective film, and heated at about 600°C. The above non-single crystal silicon (81) layer is made into a single crystal by heat treatment in a nitrogen* (N2) atmosphere for about 9 minutes, and (g) the above (
e) process! Deposit-grown silicon dioxide (day 10.
) and the protective film formed in the step ←) above are removed by etching to expose the monocrystalline silicon (81) layer produced in step 1 of (to) above. This conversion-produced single crystal silicon (81
) to form desired elements in the layer. It goes without saying that the order of the heat treatment step (f) and the protective film removal step (g) above can be exchanged as desired.

The natural laws on which this invention is based are that (a) the etching rate in a non-directional etching method differs greatly between a single crystal layer and a non-single crystal layer, especially an amorphous layer; and (b)
When growing silicon dioxide (810,) etc. in a region with a recess using the O'VD method, if the width or side of the recess is sufficiently small, the surface can be easily flattened. As a result, the non-directional Etunder filter applied to the non-single-crystal silicon (81) layer in the step (above) is mostly terminated in the silicon (81) single-crystal plane in the vertical direction; The surface of the silicon dioxide (810,) layer formed in step (e) is approximately flattened over the opening, and the protective film is etched by approximately 5 Am from the edge of the opening. Silicon dioxide (B
It has the unique effect that the ib rough surface is also flattened to a sufficiently satisfactory degree.

(5) Embodiments of the Invention Hereinafter, with reference to the drawings, the formation of an element forming region and an element isolation region in a method for manufacturing semiconductor snow making according to an embodiment of the present invention will be explained, and the structure of the present invention will be explained. 1 × 10−1 or
An amorphous silicon (Sl) layer 2 having a thickness of about 1 μm is formed using a vapor deposition method in a vacuum of less than r, and then a silicon dioxide layer 5 is formed using an OvD method or the like. Con (810
) or silicon nitride (steN4) and has a thickness of λoooo An opening 5 having a narrow, closed groove-like shape is formed approximately in the center of the element isolation region of the protective film 3. At this time, it is desirable that the width of the groove-like opening is 1 μm or less. Even if there is a vertical recess, silicon dioxide with a flat surface (st
Since it is easy to form a photoresist film 4 having a closed groove-like opening S, see FIG.
Using as a mask, an opening 6 is formed in the protective film 3. This etching method can be performed by wet method 1 using a material selected according to the material of the protective film 3, or by dry etching method. . Next, by applying a non-directional etching method through this opening 6, amorphous silicon (B1
) A part of the layer 2 is removed to form a cavity 1997 having a closed groove shape in the element isolation region. Then, the amorphous silicon (Sl) layer 2 remains in the element formation region. The only condition for the etching method used at this time is that it be non-directional, but for example, a method of dissolving with caustic potash (KOH) is suitable. As mentioned above, the etching rate for such an etching method is 5 to 10 times higher for an amorphous material than for a single crystal, so as shown in the figure, the width is wide in the left and right direction and almost covers a part of the element isolation region. It becomes hollow. Experimentally, 5μm 8F was etched on the left and right sides without leaving any traces of etching on the single crystal layer 1.
O 79 - It has been confirmed to be etched 0 see Figure 3 via the groove - mouth 6, for example using the O'VD method.
Silicon dioxide (810,) is grown in the cavity 7.

At this time, if the width of the groove-like opening 6 is equal to or greater than the height of the cavity 7, that is, the thickness of the amorphous silicon (SL) layer 2, the cavity 7 is completely filled with the silicon dioxide (8102), Moreover, if the width of the groove-like opening 6 is about 1 μm or less, even on the groove-like opening 6, silicon dioxide (l
]io,) The surface of the layer 8 is completely flattened.Next, heat treatment is performed for about 9 minutes in a nitrogen CMs atmosphere at about 600°C to completely flatten the remaining amorphous silicon (B1) layer 2. It is crystallized to form a single crystal silicon (81) layer 2. It goes without saying that this single crystallization step can be carried out by laser annealing or electron beam annealing (see FIG. 4), and the protective film 3 is removed by etching the insulating layer 8.

When the protective film 3 is made of silicon dioxide (810), it has the same quality as the insulating layer 6, so it can be easily flattened with hydrofluoric acid (1!?) (etching is possible!). 3
When silicon nitride (81sN4) is present, smooth etching is possible by using a snow vine etching method or the like.

Note that the above-mentioned single crystallization step and protective film removal step may be performed in the reverse order. (81) It was decided to intentionally introduce impurities into layer 2, and this conductivity type was changed to the substrate l and the element forming IJfi2'.
It is also obvious that even more complete element isolation is possible if the conductivity type is set to be opposite to that of the conductivity type, and a reverse negative bias is applied.

Thereafter, a desired semiconductor element is formed in the single crystallized element forming region 2' using a conventional method.

(6) As described in detail, the present invention provides a method for manufacturing a semiconductor device including a step of forming a buried element isolation layer with a flat surface without using a flattening auxiliary material. It is possible to provide.

[Brief explanation of drawings]

x, 2.3.4 -! of the present invention! A cross-sectional view of a substrate 1 showing the steps of forming an element formation region and an element isolation region in the method for manufacturing a semiconductor device according to Example J. . . . Silicon single crystal substrate, 2 . . . Amorphous silicon IJ crystallized element formation region, 3 . . . Protective film, 4 .
Photoresist film, 5... Photoresist film 4: closed groove-shaped opening formed, 6... Closed groove-shaped opening formed in the protective film, 7... Cavity, 8... diacid,
silicon layer

Claims (2)

[Claims] (1) The process of forming a non-single-crystal silicon layer on the single-crystal silicon layer, the process of forming a protective film on the non-single-crystal silicon layer, and the narrow width of the wrinkle protective film in the region corresponding to the element isolation region. The non-monocrystalline silicon layer in the device isolation region is removed by forming a glue hole in the shape of a closed groove and using a non-directional etching method through the crease opening to remove the non-single crystal silicon layer under the protective film. forming a cavity having the shape of a closed groove; filling the cavity with an insulating material; converting the non-single crystal silicon layer into a single crystal silicon layer by performing a heat treatment; removing a part of the material and the protective film to make the converted single crystal silicon layer and the layer made of the insulating material coplanar and flat; Method 0 for manufacturing a semiconductor device characterized by forming an element in a single crystal silicon layer (2) After removing the protective film, the non-monocrystalline silicon layer is converted into a monocrystalline silicon layer by using a heat treatment method. manufacturing method.