JPS6255917A - Recrystallization of semiconductor layer - Google Patents

Abstract

PURPOSE:To remove limitation on the element forming region by a method wherein the striped form of a reflection preventive film is made polygonal, and adjacent active regions of semiconductor are connected with each other so as to form a single crystalline region over a large area. CONSTITUTION:A substrate 1 and a semiconductor's active layer 3 where an element is to be made are separated with the insulation layer 2 made of an Si oxide film on a silicon substrate 1, and a reflection preventive layer 4 is formed on the active layer 3 with patterning. The active layer 3 is divided into two regions, with one of them being a semiconductor region whose ends are placed between the preventive films 4; and a connection region 7 where adjacent active region 6 is connected to. When one part of the preventive layer 4 is removed, laser light 5 is scanned lengthwise to obtain a single crystal with a large area by arranging adjoining active layers 6 along the same crystalline axis. Moreover, the active layer 3 is contacted with the substrate 1 to use the substrate 1 as a seed 8 for a crystal growth.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for recrystallizing a polycrystalline or amorphous semi-4η layer deposited on an insulator.

[Conventional technology]

In order to increase the speed and density of semiconductor devices, attempts have been made to separate circuit elements with dielectrics and manufacture semiconductor integrated circuits with low stray capacitance. There is a method of forming a four-body crystal and forming circuit elements in the semiconductor crystal. As a method for forming such semiconductor crystals, a polycrystalline or amorphous semiconductor layer is deposited on an insulator, and only the surface layer is removed by irradiating the surface with energy beams such as laser light or electron beams. There is a method of heating to form a single crystal semiconductor layer.

FIG. 3(al) to (el are cross-sectional views and top views showing the sequential steps of the conventional semiconductor device manufacturing method. First, as shown in FIG. 3(al), a P-type (100) Noricon substrate i11 1 μm of SiO in an oxidizing atmosphere at 950°C.
A □ layer (thermal oxide film) is formed as an insulating layer (2).

A semiconductor active layer (3) consisting of a polysilicon layer with a thickness of 5,000 wafers is deposited on this using the normal low pressure CVD method (third layer).
(see figure fbl). Next, as shown in FIG.
Deposit by method. The thickness of this anti-reflection film (4) is 4
It is recommended to set the number between 00 and 700 people. Next, the third
As shown in the figure (dl and fal), the above anti-reflection coating (
4) is left in a stripe shape with a width of 3 to 10 μm and a pitch of 10 to 30 μm, and the remaining portion is removed. Next, when the semiconductor device having such a configuration is irradiated with a laser beam (5) having a beam diameter of approximately 40 μm while scanning along the stripes of the anti-reflection film (4) (see Fig. 3 (see 81), the anti-reflection film is The semiconductor active layer (3) in the region where the film (4) is present absorbs about twice as much power as other regions, and becomes hotter than the region without the anti-reflection film (4).Therefore, in this state, the laser When the light (5) is scanned, after the beam has passed, the central part of the semiconductor active layer (3) sandwiched between the antireflection films (4) cools quickly, and the state of recrystallization from melting begins. That is, first, recrystallized grains with planes, which are the most dominant crystal growth direction, increase, and crystal growth using these as seeds continues from the center to the periphery, as shown by the arrow C in Figure 3. As a result, the entire surface of the semiconductor active region (6) sandwiched between the antireflection films (4) becomes monocrystalline.

[Problem that the invention seeks to solve]

Conventional recrystallization methods for semiconductor layers are performed as described above, and although single crystallization is possible within the semiconductor active region (6) sandwiched between the antireflection films (4), The orientation of the crystal axes is not necessarily the same, therefore grain boundaries generally exist under the stripes of the anti-reflection film (4), and if a device is formed in the region where the grain boundaries exist, leakage current and dark value This leads to deterioration of the electrical characteristics of the element, such as voltage variations, and there is a problem that the area in which the element can be formed is restricted.

In addition, when a part of the semiconductor active layer (3) to be recrystallized is brought into contact with the single crystal silicon of the silicon substrate (1) and crystallization is performed from there using it as a sword, the antireflection film (4) Since the sandwiched adjacent semiconductor active regions (6) continue to grow independently, there is a problem in that it is difficult to grow crystals while maintaining the plane orientation of the silicon substrate (1) over a long distance.

This invention was made to solve the above-mentioned problems, and provides a method for recrystallizing a semiconductor layer that can form a single crystal region over a large area and eliminate restrictions on the device formation area. It is something to do.

[Means for solving problems]

In the method for recrystallizing a semiconductor layer according to the present invention, the antireflection film is not shaped like a stripe, but has a polygonal shape, and adjacent semiconductor active regions are connected to each other.

[Effect]

The recrystallization method of a semiconductor layer in the present invention includes removing a part of a striped pattern of an antireflection film formed on a semiconductor active layer deposited on an insulator to connect adjacent semiconductor active regions. As a result, crystal growth generated from one crystal growth nucleus and crystal growth generated from another crystal growth nucleus interact with each other in the connected region, and from then on, the dominant crystal growth progresses in both regions, resulting in the same growth. The crystal growth generated from the crystal growth nucleus is maintained over a long distance.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
Figures fal and (bl) are a top view and a cross-sectional view showing a method for recrystallizing a semiconductor layer according to an embodiment of the present invention.

In Figure 1 (-1) and (b), +11 is a silicon base + anti, and (2) is a silicon oxide film separating the silicon substrate (1) and the semiconductor active layer (3) for manufacturing the device. (3) is a semiconductor active layer to be recrystallized, and (4) is an antireflection film made of silicon nitride.

In the method of recrystallizing a semiconductor layer according to this embodiment, FIG.
~ (An anti-reflective film made of a silicon nitride film is patterned through the same steps as the conventional method shown in el. In this patterning, in the conventional method, the anti-reflective film (4) is patterned in a stripe shape and heated. The distribution was controlled, but in the method of this embodiment, a part of the striped anti-reflection ill +41 is removed and adjacent regions are connected to each other.

After recrystallizing the sample 4 thus formed by scanning it with a laser beam (5), the anti-reflection film (4) was removed and SOI/M was formed according to the usual MO3 production process.
An OS semiconductor device is manufactured.

Next, the operation will be explained. A laser beam (5) is irradiated directly onto the semiconductor device configured as described above while scanning. The semiconductor active layer (3) according to the invention consists of two regions. One is a semiconductor active region (6) sandwiched between anti-reflective 1F films (4) at both ends, and the other is an adjacent semiconductor active region (6).
) is a connection region (7) that connects the two. In the semiconductor active region (6) sandwiched between the anti-reflective films (4) at both ends, the semiconductor active layer (3) in the region where the anti-reflective film (4) exists absorbs about twice as much power as in other regions. , the temperature becomes higher than the area without the antireflection film (4). Therefore, when the laser beam (5) is scanned along the vertical direction in this state, after the beam passes, it is quickly cooled down in the central part of the semiconductor active region (6) sandwiched between the anti-reflection films (4). A recrystallization state begins from melting. In this case, first, a 111 crystal with a plane which is the most dominant crystal growth direction t~ or 1 so thick 1,
Since crystal growth lζ, which always uses niboshi as seeds, occurs from the center to the periphery as shown by the arrow △ in Figure 1,
Against! Half sandwiched between Ij prevention film (4)! The entire surface of the 1-body layer 1 region (6) becomes crystallized. In the continuous f111 region (7) that connects adjacent semiconductor active regions (6), both ten-nine active regions (6) are melted at the same time, so when cooling recrystallization occurs, the two regions ( 6) has more crystal growth than the same 7 growth nuclei (1 circle).

In this way, since the adjacent semiconductor active regions (6) have the same crystal axis, ji'+ crystallization can be performed over a large area without any blurring 1' boundary. Furthermore, by making the width and pinch of the antireflection film (4) in the connecting region (7) the same as in other parts, crystallization can be performed over the entire surface without disturbing the control of heat distribution.

In the above embodiment, the entire semiconductor active layer (3) is in contact with the oxide insulating layer (2), and the seeds of crystal growth are recrystallized with a plane, which is the most dominant crystal growth direction in polycrystalline silicon. However, as shown in Figure 2, a part of the semiconductor active layer (3) to be recrystallized was brought into contact with the Noricon substrate +1. ), and the same effect as in the above embodiment can be obtained. In this case, the plane orientation of the silicon substrate [11] can be grown for a long time while always being mutually corrected in the adjacent semiconductor active regions (6) in the connection region (7).

〔Effect of the invention〕

As described above, according to the present invention, the anti-reflection film is , since we have connected at least part of the live with adjacent regions,
There is an effect that a method for recrystallizing a semiconductor layer can be obtained in which single crystallization can be performed not only in the region sandwiched between the antireflection films but also over the entire surface.

[Brief explanation of drawings]

FIGS. 1a) and 1f) are a cross-sectional view and a top view showing a method for recrystallizing a semiconductor active layer according to an embodiment of the present invention,
FIG. 2 is a sectional view showing a method for recrystallizing a semiconductor active layer according to another embodiment of the present invention, and FIGS. It is a diagram. (11 is a silicon substrate, (2) is an insulating layer, (3) is a semiconductor active layer, (4) is an antireflection film, (5) is a laser beam, (
6) is the semiconductor layer 1 [9r1 region, (7) is the connection region, (
8) is a seed. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) In a semiconductor layer recrystallization method in which a semiconductor active region of a semiconductor layer deposited on an insulator is melted and recrystallized by energy rays such as a laser or an electron beam, the reflection of the energy rays is suppressed and the area is isolated from other parts. 1. A method for recrystallizing a semiconductor layer, comprising patterning an antireflection film that selectively forms regions into which a large amount of energy is incident so as not to divide the semiconductor active region. (2) The method for recrystallizing a semiconductor layer according to claim 1, further comprising a portion that is in contact with the semiconductor active region and serves as a seed for crystal growth. (3) The method for recrystallizing a semiconductor layer according to claim 1, wherein the antireflection film has a polygonal shape.