JPS5933847A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable to enhance evenness, and to attain integration of much more high density of a semiconductor device by a method wherein an insulating film is selectively removed, semiconductor layers are formed in the removed parts according to epitaxial growth technique under the depressurized condition, and respective semiconductor elements are formed therein. CONSTITUTION:After boron is introduced according to ion implantation to the surface layer part 11a of a P type silicon substrate 11 as channel doping under element is isolation films, the oxide film 12 to constitute the element isolation insulating film is formed according to thermal oxidation. Then the oxide film 12 at the active regions, namely at the prescribed positions to be made as the MOS type semiconductor elements forming parts are selectively removed according to photoengraving technique and etching technique, and opening parts are formed. By performing epitaxial growth under the depressurized condition in the opening parts thereof, even epitaxial layers 13 are formed. By forming the N channel MOS type semiconductor elements on the epitaxial layers 13 thereof in succession, the semiconductor device is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device formed by arranging semiconductor elements, and particularly to a method for separating elements.

Conventionally, isolation between elements in this type of semiconductor device has generally been performed by selective oxidation technology.

However, when using this method, the oxide film sinks into the active region, called a bird's beak, and the unevenness, called a bird's head, arises due to the swelling of the periphery of the oxide film.The former is a constraint on high-density integration of semiconductor devices. At the same time, the latter has become inconvenient for multilayer wiring technology that accompanies high-density integration.

The present invention was made in view of the above circumstances, and its purpose is to provide a method for manufacturing a semiconductor device that improves the flatness of a semiconductor device made of semiconductor elements and enables higher-density integration. There is a particular thing.

In order to achieve such an object, the present invention selectively removes an insulating film formed on a substrate, forms a semiconductor layer on the removed portion by epitaxial growth technology under reduced pressure,
Each semiconductor element is formed here.

That is, selective epitaxial growth technology under reduced pressure is used to form the active region and to complete the isolation between elements, and instead of using the selective oxidation method that involves bird's beaks and bird's heads, conventional normal pressure (760 torr) growth technology is used. ) In the selective epitaxial growth technique for silicon performed below, abnormal growth at the periphery of the silicon island results in a film thicker at the periphery than at the center, and it is necessary to strictly control various growth conditions to reduce this tendency. However, by using a selective epitaxial growth technique under reduced pressure, it has become possible to easily suppress the swelling in the peripheral area.

Under reduced pressure, e.g. dichlorosilane 5IH11CZ21
Trichlorosilane Si HCL8+Silicon tetrachloride S s
Using an epitaxial growth technique in which a silicon source gas such as C4 is pyrolyzed with hydrogen as a carrier gas, or hydrogen chloride gas HC1 is used together with the silicon source gas or monosilane gas SiH4 under reduced pressure and hydrogen is used as a carrier gas. Oxide film (Si02) is grown using epitaxial growth technology that is thermally decomposed as
Alternatively, by growing a silicon epitaxial layer in the opening using an insulating film such as a nitride film (st8N4) as a mask, it is easier to achieve selective growth compared to the conventional selective epitaxial growth technique under tightly controlled atmospheric pressure. It was confirmed that (polysilicon does not grow on the oxide film or nitride film) and that a selective epitaxial growth layer with excellent flatness can be formed. In addition, the insulating film as the element isolation film is formed by forming openings by photolithography or the like in the insulating film formed over the entire surface, without using selective oxidation, so that the insulating film has a bird's-eye view.

There is no room for birds' heads to form.

FIG. 1 shows an example of the pressure dependence of the flatness of a selective epitaxial layer obtained using dichlorosilane as a silicon source and hydrogen as a carrier gas at 1080° C. using an oxide film as a mask. Flatness is determined by the thickness B at the center of the silicon layer (3) formed in the opening of the oxide film (2) provided on the substrate (1) with respect to the thickness A at the periphery in FIG. Expressed as a ratio.

It can be seen from FIG. 1 that the flatness can be easily and dramatically improved by selective epitaxial growth under reduced pressure, particularly at 80 torr or less.

The reason for this improvement is the carry gas concentration,
When conditions such as silicon source gas (e.g. dichlorosilane) and temperature are kept the same, when epitaxial growth is performed under reduced pressure, the growth rate is slower than that under normal pressure (approx. 2% reduction at 4Qtorr) and the silicon substrate surface The mean free path of silicon atoms becomes longer (4
This is thought to be due to the effect of Q torr (approximately 19 times).

Next, an example of forming an N-channel MO8 type semiconductor device will be described with reference to the drawings.

First, as shown in FIG. 3, boron is introduced into the surface layer (lla) of the P-type silicon substrate (11) as a channel dope under the element isolation film by ion implantation, and then the element isolation insulating film is formed by thermal oxidation. An oxide film (J2) is formed. Next, photolithography and etching techniques are used to form the active region, that is, the MO8 type semiconductor (5).
is selectively removed to form an opening. Next, epitaxial growth is performed in this opening under reduced pressure (4 Qtorr in this example), thereby forming a flat epitaxial layer (13).

Subsequently, by forming an N-channel MO8 type semiconductor element on this epitaxial layer (13) by a conventional method, a semiconductor device as shown in FIG. 4 is obtained. That is, in FIG. 4, (14) and (1,5) are the source and drain consisting of one diffusion layer, and (16) is the gate (17).
) is an electrode made of aluminum, (18) is a contact diffusion region, and (19) is an oxide film for interlayer insulation,
(19a) is a gate oxide film.

In addition, in the above-mentioned example, a method of thermally oxidizing the surface of the P-type silicon substrate (11) was used as a method of forming the oxide film (12), but this is not possible using other methods, such as forming the oxide film (12).
A method of forming a polysilicon layer on 1) and then oxidizing it entirely, or a method of depositing it by CVD or the like may be used.

Furthermore, the isolation film between elements is limited to an oxide film, for example, C.
Other insulating films such as a nitride film formed by a VD method or the like may also be used.

Note that boron may be introduced into the substrate (11) through a thin oxide film on the surface that is naturally formed during the substrate forming process, or by removing this oxide film and directly implanting ions.

Further, in the above-described embodiments, only the case of manufacturing a semiconductor device made of an N-channel MO8 type semiconductor element has been described, but the present invention is not limited to this, and the P-channel MO8 type semiconductor element having the reverse conductivity type is manufactured. It goes without saying that the present invention is equally effective when applied to the manufacture of semiconductor devices made of type semiconductor elements.

Furthermore, in the case of a solid-state imaging device, for example, the selective epitaxial growth technique under reduced pressure can be applied to parts that are not involved in the original function of the semiconductor device, such as the peripheral part of the chip excluding the central part where the light receiving elements are arranged. By applying this, or furthermore, peripheral regions other than those involved in the above-mentioned original functions are formed in the epitaxial layer formed thereby, such as a monitor transistor or various breakdown voltages.

By providing a region for forming a pattern for monitoring continuity tests, etc., it is possible to further improve the flatness and selectivity of the selective epitaxial layer forming portion under reduced pressure, and to improve the quality of the device.

In other words, in silicon selective epitaxial growth using a silicon oxide film as a mask material, selectivity and flatness are affected by the area ratio of silicon to silicon oxide (8i/S1o,), and the area of Si//5io2 Since the selectivity and flatness are improved by increasing the ratio, the selectivity and flatness are further improved by forming a selective epitaxial layer in areas other than the original semiconductor device.

As explained above, according to the present invention, a semiconductor layer is formed in an opening formed by selectively removing an insulating film by an epitaxial growth technique under reduced pressure, and a semiconductor element is provided through a simple process. The device isolation technology using the oxidation method eliminates the unavoidable bird's beak and bird's beak, and also suppresses the mounding around the semiconductor layer that makes up the active region, allowing for higher density isolation compared to the conventional method. It becomes possible to manufacture a semiconductor device that can be integrated and can easily be applied to multilayer wiring.

[Brief explanation of drawings]

FIG. 1 is a graph showing an example of pressure dependence of the flatness of a selective epitaxial layer, FIG. 2 is a diagram for explaining the flatness in that case, and FIGS. 3 and 4 are examples of the present invention. FIG. 3 is a cross-sectional view of each step of a semiconductor device to which the method is applied. (11)...P-type semiconductor substrate, (12)...oxide film, (13)...epitaxial layer, (14),
(15)...source, drain, (16)...
Kate. Agent Makoto Kuzuno - Written amendment to formal binding procedure (voluntary) 2. Name of the invention Method for manufacturing a semiconductor device 3. Relationship with the person making the amendment Hitoshi Katayama, representative of the patent applicant Department 4, Agent 54 Amendment Column 6 for Detailed Description of the Invention in the Target Specification Contents of Amendment (1) "Carry gas" in lines 16-17 and line 20 on page 3 of the specification is corrected to "carrier gas." (2) "Carry gas" on page 4, line 15 of the same book is corrected to "carrier gas." (3) [Carry gas] on page 5, line 5 of the same book is corrected to "carrier gas." (4) "Channel dope" in lines 16-17 of the same page of the same book is corrected to "channel cut."that's all

Claims (3)

[Claims] (1) In a method of manufacturing a semiconductor device in which semiconductor elements are arranged and separated from each other by an inter-element isolation insulating film, a process of forming an insulating film on a substrate and selectively forming a semiconductor element forming portion of this insulating film is performed. removing to expose the substrate;
1. A method for manufacturing a semiconductor device, comprising the step of forming a semiconductor layer on an exposed substrate by epitaxial growth technology under reduced pressure, and forming a semiconductor element on the semiconductor layer. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the pressure is 80 torr or less. (3) The method for manufacturing a semiconductor device according to item 1 or 2, characterized in that the semiconductor element is an MO8 type semiconductor element.