JPS6236855A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To simplify the manufacturing steps by forming a laser light hard transmitting film on a channel region to form a region in which a crystal grain boundary is not formed as a channel region to effectively form an FET having preferable characteristics in an SOI. CONSTITUTION:A silicon oxide film 6 of an insulating film is coated on a silicon substrate 5 of a semiconductor substrate, a non-doped polycrystalline silicon layer or an amorphous silicon layer 7 is then coated, and double films of a nitride film/silicon oxide film 8 are formed as a laser light reflection preventive film. Then, a polycrystalline silicon film 9 is formed as the laser light hard transmitting film and as a mask for forming the source and drain impurity region. Thereafter, Ar<+> laser light is emitted while scanning. The polycrystalline silicon layer or the amorphous silicon layer 7 are efficiently dissolved and recrystallized. A crystal grain boundary is not generated even after the recrystallization in the layer 7 under the layer 9. With the layer 9 as a mask arsenic ions are implanted to form N-type high impurity region 10 for the source and drain.

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing a semiconductor device in which an FET is formed in SOI, the method comprising: laser light applied to a channel region so as to prevent grain boundaries from occurring in the channel region; The poorly permeable film is used as it is as a mask when forming source/drain impurity regions.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which an FET with good electrical characteristics is formed on SOI.

[Conventional technology]

In order to increase the density and integration of semiconductor integrated circuits, attempts have been made to form silicon layers into a multilayer structure and form devices such as FETs in each silicon layer.

That is, a polycrystalline silicon layer or an amorphous silicon layer is formed on an insulating film of a silicon substrate 1-, and then this is melted and recrystallized with laser light to obtain a semi-crystalline silicon layer. It is. By forming active devices such as MOS transistors on this single crystal silicon layer, a semiconductor integrated circuit is made into multiple layers.

[Problem that the invention seeks to solve]

As mentioned above, in order to recrystallize a polycrystalline silicon layer or an amorphous silicon layer, laser light is irradiated to melt it. Since the spot diameter of the laser beam is generally smaller than the wafer diameter, the laser beam is irradiated with an intensity distribution and is not uniformly melted. Therefore, the silicon layer has so-called crystal grains on both sides along the trajectory of the scanning beam. A grain boundary is created.

FIGS. 8(a) and 8(b) are diagrams for explaining the problems of the conventional example when a MOS transistor is formed in a silicon layer where crystal grain boundaries have occurred. The source and drain points, 3° and 4, are grain boundaries. When the grain boundary 3 is formed to connect the source and drain as shown in FIG. 8(a), the diffusion coefficient of impurities along the grain boundary 3 is extremely high, so the source and drain If the bulk S1 is processed under thermal process conditions after forming the bulk S1, short-circuit phenomena between the source and the drain occur frequently.

Furthermore, as shown in FIG. 8(b), if the grain boundaries 4 are formed to block the channel between the source and drain, the average mobility of charges between the source and drain becomes extremely low. , 11) Normal electrical characteristics cannot be obtained. In this way, if crystal grain boundaries occur in the channel region of a MOS transistor, a MOS transistor with good characteristics will be produced.
) cannot form a transistor.

The present invention was created in view of the problems of the conventional example described in L, and provides a method for manufacturing a semiconductor device that makes it possible to reliably and easily form an FET that does not include grain boundaries in the channel region. The purpose is to provide.

[Means to solve the problem]

The method for manufacturing a semiconductor device in which an FET is formed on an SOI according to the present invention includes a semiconductor substrate 5, as shown in FIGS. 1i to 6.
A polycrystalline or amorphous silicon layer 7 is formed on the insulating film 6 of L.
After the first step, a second step of depositing a laser beam antireflection film 8 on the silicon layer 7.
After the second step, there is a third step of depositing a laser light-resistant film 9 having a shape corresponding to the channel region of the FET to be formed on the antireflection film 8; , irradiating a laser beam from one side of the laser beam hardly permeable film 9;
a fourth step of converting the polycrystalline or amorphous silicon layer 7 into a single crystal by recrystallization; and "After the fourth step, masking the laser beam-resistant l! 19, a fifth step of forming an impurity region 10 as a source/drain in the silicon layer 7, and after the fifth step, the gate the sixth l2 step for forming the insulating film 11;
After the step, the method is characterized in that it includes a seventh step of forming a gate electrode 12 on the gate insulating film 11.

[Effect]

As shown in FIG. 7, since a film 9 that hardly transmits the laser beam is formed on the channel region, the temperature distribution in the channel region of the silicon layer 7 when the laser beam is irradiated changes so that the laser beam hardly transmits. It is determined by the shape of the transparent film 9, etc., is almost unaffected by the intensity distribution of the laser beam, and has low transparency I.
! Since the area near the center of 19 is the lowest temperature, this is the core.
Single crystallization uniformly spreads to the outer periphery of the impermeable film 9, which is at the highest temperature.In this way, no grain boundaries are generated at least in the silicon layer 7 in the channel region. In addition, since the laser light-impermeable film is used as it is as a mask for forming impurity regions as sources and drains, it becomes a self-aligned (self-aligned) V-immersion method, which improves accuracy by 1- and simplifies the process. .

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. 1 to 6 are cross-sectional views illustrating a manufacturing method for forming an N-channel MOS transistor in a Sot according to an embodiment of the present invention.

First '1': 17 gm of silicon oxide film 6, which is an insulating film, is deposited on silicon substrate 5, which is a conductor substrate, and then 0.4 gm of non-doped polycrystalline silicon layer or amorphous silicon layer 7 is deposited. to adhere to. Further, a double film of nitride film/silicon oxide film 8 is formed as a laser beam anti-reflection film 11 (
Figure 1).

Next, a polycrystalline silicon film 9 as a mask for forming a laser beam-impermeable film and a source-drain impurity region is coated with a 0.0-.
Forms 24-0.4gm. This thickness is determined based on two requirements: laser light blocking performance and masking performance. Thereafter, the polycrystalline silicon film 9 is patterned in accordance with the shape of the channel region of the transistor to be formed (FIG. 2).

Next, Ar laser light is applied while scanning.

Since reflection is prevented by the anti-reflection film 8, the polycrystalline silicon layer or the amorphous silicon layer 7 is efficiently dissolved and recrystallized by the laser beam. In this case, as in the conventional example, grain boundaries are generated in the recrystallization process due to the temperature distribution of the silicon layer caused by the intensity distribution of the laser beam. However, no crystal grain boundaries occur in the silicon layer of the polycrystalline silicon film 9 normal f and in the vicinity of its periphery. This is because the temperature distribution of the silicon layer 7 below the barely permeable film 9 (channel region) is determined by the width of the hardly permeable film, etc., as shown in FIG. 7, and is hardly affected by the intensity distribution of the laser beam. be. In this way, no crystal grain boundaries are generated in the silicon layer 7 (channel region) below the polycrystalline silicon layer 9, which serves as a hardly permeable film, even after recrystallization.

Next, using the same polycrystalline silicon layer 9 as a mask, arsenic ions are implanted to form N-type highly impurity regions 10 for sources and drains (FIG. 3). Thereafter, after removing the polycrystalline silicon layer 96, the antireflection film 11, and the film 8, the recrystallized silicon layer 7 is patterned to perform element isolation (FIG. 4).

Next, after forming the gate oxide film 11, poron ions are implanted to control the dark voltage of the transistor.
The surface of the silicon layer 7 under the silicon layer 1 is made into a P type. Thereafter, a gate electrode 12 (polycrystalline silicon or aluminum) is formed in the channel region (FIG. 5).

Next, PS with high phosphorus concentration was used as a passivation insulating film.
After forming the G film 13, the contact window is opened [I L,
Furthermore, after forming an aluminum layer, it is patterned to form wiring 14 (FIG. 6).

As described in -1-1 below, according to the embodiment of the present invention, no crystal grain boundaries are generated in the channel region, so that the average mobility of charges between channels is reduced or problems caused by diffusion of impurities are prevented. Short circuits between the source and drain can be prevented.

In addition, the polycrystalline silicon layer 9, which is a laser beam-resistant film in the channel region used to prevent the generation of grain boundaries, can also be used as a mask for forming sources and drains, which simplifies manufacturing. In addition, since the channel length is determined in a self-aligned manner, a highly accurate transistor can be formed.

〔Effect of the invention〕

As explained above, according to the present invention, since the channel region is a region in which no crystal grain boundaries that cause characteristic deterioration occur, it is possible to reliably form an FET with good characteristics on SOI, and also to avoid crystal grain boundaries. Since the laser light-impermeable film on the channel region used for prevention of occurrence is also used as a mask for forming the source/drain, the manufacturing process can be simplified. Furthermore, since the channel region is determined in a self-aligned manner, a highly accurate FET can be formed, and therefore an FET with good characteristics can be obtained.

[Brief explanation of the drawing]

FIGS. 1 to 6 illustrate the case of forming an N-channel MOS transistor on SOI according to an embodiment of the present invention! FIG. 3 is a cross-sectional view for explaining the manufacturing method. FIG. 7 is a diagram showing the temperature distribution of the silicon layer when laser light is irradiated near the laser light-impermeable film according to the embodiment of the present invention. FIG. 8 is a pattern diagram for explaining the problems of the conventional example when a MOS transistor is formed in a silicon layer in which grain boundaries occur. 5... Silicon substrate (semiconductor substrate) 6... Silicon oxide film (insulating film) 7... Polycrystalline or arithmetic quality silicon layer 8... Vacuum film/silicon oxide film (antireflection film) 9 ...Polycrystalline silicon layer (laser light hardly permeable film) IO...Impurity region (source and drain) t11...Gate oxide film (gate insulating film) 12...
Gate electrode 13...PSG film 14...Wiring 1) Shim 1 was also assembled beforehand. Gongmeng Chiram L Yue Asagu b Ko No. 5 Other Book 4 PSG Distribution 1312 Floating in the City of Haruka - 1 Figure 7 / kr: Midori, Singing One Desire Beli's Musical Library Unya Atsushi Plo Figure 6 Kin (-) Arc A Arrogant Moon's Inferior Dimension 5-Nau-1-3Y, Konoko 08 House, Hair Roburizumi Utsu Figure 8

Claims (1)

[Claims] A first step of forming a polycrystalline or amorphous silicon layer on an insulator of a semiconductor substrate; and after the first step, coating a laser beam antireflection film on the silicon layer. After the second step, a third step of depositing a laser beam-resistant film having a shape corresponding to the channel region of the FET to be formed on the anti-reflection film; After the step 3, a fourth step of irradiating the laser light from above the laser light-resistant film to make the polycrystalline or amorphous silicon layer into a single crystal by recrystallization; After the step, a fifth step of forming an impurity region as a source/drain in the recrystallized silicon layer using the laser beam impermeable film as a mask; a sixth step of forming a gate insulating film after removing the transparent film and the antireflection film; and a seventh step of forming a gate electrode on the gate insulating film after the sixth step. SOI characterized by including
(Silicon On Insulator) and FET (
A method for manufacturing a semiconductor device that forms a FieldEffectTransister.