JPH04107815A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent malfunction or characteristic fluctuation of element in a structure having a single crystal semiconductor layer formed on an insulating film by previously removing at least a part of non-single crystal semiconductor corresponding to the high temperature part of a fused non-single-crystal semiconductor and then recrystallizing the non-single crystal semiconductor. CONSTITUTION:An insulator film, i.e., a silicon oxide film 2, is formed on a single crystal silicon substrate 1 and a non-single crystal semiconductor layer, i.e., a polysilicon layer 3a, is formed thereon. A part of the polysilicon layer 3a at a part corresponding to the region for forming a reflection preventing film 4 is then removed with a patterned resist 10 as a mask. The resist 10 is then removed, a silicon nitride film 4 is entirely formed with a predetermined thickness as the reflection preventing film, the silicon nitride film 4 is patterned with a resist 11 as a mask and then the resist is removed. The polysilicon layer 3a is then fused and recrystallized through laser irradiation thus forming a single crystal silicon film 3b on the silicon oxide film 2. According to the method, no crystal grain boundary nor sub-crystal grain boundary occur at the time of 501 layer formation and thereby no crystal defect occur in spite of oxidation process or heat treatment.

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, a method for manufacturing a semiconductor device by melting a non-single crystal semiconductor to form a molten semiconductor and forming a temperature distribution in the molten semiconductor. The present invention relates to a method for manufacturing a semiconductor device in which a non-single crystal semiconductor layer is formed on an insulating film.

[Prior art] Conventionally, 5oI (Sil
The structure (icon On In5ulator) is known. When using the Sol structure as a substrate, the silicon layer needs to be single crystal in order to form a device with performance equivalent to that of bulk silicon.

The method for forming a single crystal silicon film on an insulating film is as follows:
Conventional methods include a method of implanting oxygen ions into a single crystal semiconductor substrate to form an oxide film in the substrate (SIMOX), a method of melting and recrystallizing a non-single crystal semiconductor on an insulating film by heating it with a heater, and a method of melting and recrystallizing a non-single crystal semiconductor on an insulating film by heating it with a heater. Crystallization methods are known. Among these, in particular, the method using energy beam irradiation is an indispensable technique for forming tertiary elements.

Here, a tertiary element is a multi-layered integrated circuit layer, which used to be a single layer, with an insulating film sandwiched between them, and has a dramatic improvement in functionality and degree of integration compared to conventional tertiary elements. can be achieved. High-power lasers or electron beams are considered as energy beams used in the melt recrystallization method, but a method using a laser is suitable for forming a single-crystal semiconductor layer on an insulating film because of its ease of operation. ing.

In order to form a single crystal semiconductor layer by this melt recrystallization method using laser irradiation, it is necessary to control the temperature distribution in the molten semiconductor and cause recrystallization from a predetermined location. Various methods have been proposed to control temperature distribution, but no matter which method is used, crystallization starts from a low temperature area and progresses toward a high temperature area. Therefore, after the high-temperature portion is crystallized, subgrain boundaries and grain boundaries will exist. An antireflection coating method is conventionally known as an example of a method for controlling temperature distribution. These are disclosed, for example, in USP 4,822,752.

FIGS. 4A and 4B are schematic diagrams showing the relationship between the 5C)I film formed by the conventional antireflection film method and crystal subgrain boundaries. Referring to FIGS. 4A and 4B, a silicon oxide film 2 is formed on a single crystal silicon substrate 1, and a single crystal silicon film 3b is formed on the silicon oxide film 2.

Anti-reflection films 14 are formed on the single crystal silicon film 3b at predetermined intervals, have a predetermined width, and extend in a fixed direction. As shown by arrows in FIG. 4B, crystallization of the semiconductor melted by laser irradiation starts between the antireflection films 14 and progresses toward the antireflection films 14.

As a result, subgrain boundaries 20 are generated under the antireflection film 14 at positions where crystals grown from both sides collide.

However, since such subgrain boundaries 20 and grain boundaries occur at fixed positions in the sample structure, it was conventionally thought that there would be no inconvenience during element formation.

[Problems to be Solved by the Invention] As mentioned above, among the conventional melt recrystallization methods using a laser, an antireflection film method that uses an antireflection film to control temperature distribution is known. In the antireflection coating method, crystal subgrain boundaries 20 are generated under the antireflection coating 14. Since the crystal subgrain boundaries 20 occur at fixed positions in the sample structure,
It was believed that there would be no inconvenience during device formation. but,
It has been clarified that the disadvantage is that the variation in characteristics of devices formed using the conventional antireflection coating method is quite large. Therefore, when the crystallinity of a semiconductor film that had gone through a normal device formation flow was investigated, it was found that new crystal defects that were not observed immediately after the semiconductor film was formed were generated.

FIG. 5 is a state diagram showing the crystal state immediately after laser recrystallization in the conventional antireflection coating method. Referring to FIG. 5, in this state, secco-etching is performed to make defects obvious. As is clear from this state, almost no defects are generated immediately after recrystallization, except for the presence of crystal subgrain boundaries 20 in regions that have become high temperature areas due to temperature distribution control. That is, except for the crystal subgrain boundary 20, the other defect density is less than 10'c+n-2,
It has crystallinity equivalent to that of bulk semiconductors.

However, when evaluating the crystallinity using an oxidized semiconductor film, it is found that many crystal defects have occurred. FIG. 6 is a state diagram showing the crystal state after laser recrystallization and oxidation in the conventional antireflection coating method. By referring to FIG. 6, it can be seen whether many crystal defects 30 have occurred or not. This crystal defect 30 appears linear, so
Although it is difficult to directly compare the density with that of point defects, they still occur on the order of 3 x 10'cm-2. Further, these crystal defects 30 are generated from the crystal subgrain boundaries 20, and most of them are generated along the (110) plane or the (111) plane.

Furthermore, it has been found that similar defects occur even when heat treatment is performed instead of an oxidation process. It was found that the defect density of crystal defects obtained only by this heat treatment was one order of magnitude smaller than that obtained by undergoing an oxidation process. From these facts, crystal defects are caused by point defects such as surplus silicon or vacancies that exist at crystal grain boundaries or crystal sub-grain boundaries immediately after semiconductor film formation, and are caused by stress applied during oxidation or annealing processes in a single crystal semiconductor. It is thought that these defects occur due to movement within the layer, that is, those that remain as point defects or those that form branes and become stacking faults.

It is thought that the occurrence of crystal defects is responsible for increasing the variation in device characteristics.

In addition, if a crystal defect occurs across the channel region, impurities will diffuse along the crystal defect, causing a fatal failure in which the source/drain becomes conductive, causing device malfunction. was there. Therefore, in order to improve the performance of the device, it is necessary to prevent such crystal defects from occurring.

This invention was made in order to solve the above-mentioned problems, and provides a semiconductor that can effectively prevent variations in device characteristics and malfunctions in a structure in which a single crystal semiconductor layer is formed on an insulating film. The purpose is to provide a method for manufacturing the device.

[Means for Solving the Problems] A method for manufacturing a semiconductor device according to the present invention is to melt a non-single crystal semiconductor to form a molten semiconductor, form a temperature distribution in the molten semiconductor, and form a single crystal semiconductor on an insulating film. In a method for manufacturing a semiconductor device in which a layer is formed, at least a part of a region of the non-single crystal semiconductor corresponding to a region that should become a high temperature part in the molten semiconductor when the non-single crystal semiconductor is melted is removed in advance, and then the non-single crystal semiconductor is reused. Characterized by crystallization.

[Operation] In the method for manufacturing a semiconductor device according to the present invention, at least a part of the region of the non-single crystal semiconductor corresponding to the region that should become a high temperature part in the molten semiconductor when the non-single crystal semiconductor is melted is removed in advance. Since the single crystal semiconductor film is formed on the insulating film, crystal grain boundaries and subgrain boundaries do not occur, and crystal defects are prevented from forming during the oxidation process and heat treatment process during device formation. Never occurs.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

FIGS. 1A to 1D are cross-sectional structural diagrams for explaining a manufacturing process of a semiconductor device having a Sol structure using an antireflection film according to an embodiment of the present invention. The manufacturing process of this embodiment will be described with reference to FIGS. 1A to 1D. First, single crystal silicon J! A silicon oxide film 2 serving as an insulator film is formed on the lfl, and a polysilicon layer 3a serving as a non-single crystal semiconductor layer is formed on the silicon oxide film 2.
or formed. Next, as shown in FIG. 1B, a resist 10 is coated on the polysilicon layer 3a so that a part of the polysilicon layer 3a corresponding to a region where an antireflection film 4 to be described later will be formed can be removed. Butter it. Using patterned resist 10 as a mask, a portion of polysilicon layer 3a is removed. Next, as shown in FIG. 1C, after removing the resist 10 (see FIG. 1B), a silicon nitride film 4 of a predetermined thickness, which will serve as an antireflection film, is formed over the entire surface. A resist 11 is applied and patterned into a predetermined shape. Using the resist 11 as a mask, the silicon nitride film 4 is buttered and then the resist is removed.

Next, as shown in FIG. 1D, the polysilicon layer 3a (see FIG. 1C) is melted and recrystallized by laser irradiation.
A single crystal silicon film 3b is formed on silicon oxide film 2. After recrystallization, the silicon nitride film 4 is removed and a device is formed using a normal process flow.

As described above, in this embodiment, the bosilicon layer 3 is removed after previously removing the portions where the conventional crystal grain boundaries and crystal sub-grain boundaries occur.
Since the monocrystalline silicon film 3b is formed by melting and recrystallizing the sOI layer, crystal grain boundaries and crystal sub-grain boundaries do not occur during the formation of the sOI layer, so the above-mentioned crystal defects occur even after the oxidation process and heat treatment. That's not true. Therefore, it is possible to effectively prevent the occurrence of variations in element characteristics and malfunctions, which have been problems in the past, and it is possible to improve the performance of the semiconductor device.

In the embodiments shown in FIGS. 18 to 1D, no seeds are provided, but even if seeds are provided, the steps are basically the same. Plan 2 FIG. 2 is a plan view for explaining the manufacturing process when a seed is provided in the manufacturing process of the semiconductor device shown in Plan I to FIG. 1D. Referring to FIG. 2, a single-crystal silicon substrate having a main surface or a (100) plane is used as the seed 5. When forming the Sol film, the antireflection film 4 is generally provided in the <100> direction, and the laser beam is scanned in either the <ioo> direction or the <110> direction. Note that even when the seed 5 is provided, the same effects as in the embodiments shown in FIGS. 18 to 1D can be obtained.

FIGS. 38 to 3C are cross-sectional structural views for explaining a manufacturing process of a semiconductor device having an SOI structure using an antireflection coating method according to another embodiment of the present invention. 3rd A
A manufacturing process according to this other embodiment will be described with reference to FIGS. 3c to 3c. First, as shown in FIG. 3A, a silicon oxide film 2 is formed on a single crystal silicon substrate 1.

After forming the polysilicon layer 3a on the silicon oxide film 2, the polysilicon layer 3a is formed in the same manner as shown in FIG. 1B.
Butter a. In other words, silicon nitridation, which will be discussed later! ! A portion of the polysilicon layer 3a where the (antireflection film) 4 is to be provided is removed in advance. After that, the resist (not shown) is removed. Next, as shown in FIG. 3B, silicon oxide 1!12 is deposited on the entire surface using the CVD method, and a silicon oxide film 12 is buried in the portion where the polysilicon layer 3a has been removed using the etch-back method. Next, as shown in FIG. 3C, a silicon nitride film (anti-reflection film) 4 is formed using a method similar to the manufacturing process shown in FIG. 1C, and a polysilicon layer 3a (third
(see figure B) is melted and recrystallized to form a single crystal silicon film 3b on the silicon oxide film 2. Here, in this other embodiment, planarization can be performed by burying the silicon oxide film 12. Furthermore, since the silicon oxide film 12 has a lower softening temperature than the silicon nitride film 4, stress during recrystallization can be alleviated compared to the shape shown in FIG. 1D.

Note that in this example, S
Although the OI film has been described, the present invention is not limited thereto, and the manufacturing method of the present invention can also be applied to an SO film formed by creating a temperature distribution in molten silicon using another method.

In other words, an SO2 film formed by creating a temperature distribution in molten silicon has crystal sub-grain boundaries or grain boundaries in the high-temperature areas, so it cannot be formed using other methods that create a temperature distribution. The same effect can be obtained even in the case of a SO2 film by applying the manufacturing method of the present invention.

Further, in this embodiment, a method of forming an element having a single layer of 5of# structure has been described, but the present invention is not limited to this, and can also be applied to a three-dimensional circuit element f structure.

[Effects of the Invention] As described above, according to the present invention, a non-single crystal semiconductor is melted to form a molten semiconductor, a temperature distribution is formed in the molten semiconductor, and a single crystal semiconductor layer is formed on an insulating film. In a method for manufacturing a semiconductor device, at least a part of a region of a non-single crystal semiconductor corresponding to a region that should become a high temperature part in the molten semiconductor when the non-single crystal semiconductor is melted is removed in advance and then recrystallized. Therefore, when forming a single-crystal semiconductor film on an insulating film, grain boundaries and sub-grain boundaries do not occur, and crystal defects do not occur during the oxidation process or heat treatment process during device formation. Therefore, it has been possible to provide a Jj method for manufacturing a semiconductor device that can effectively prevent variations in device characteristics and malfunctions in a structure in which a single crystal semiconductor is formed on an insulating film.

[Brief explanation of the drawing]

18 to 1D are cross-sectional structural diagrams for explaining the manufacturing process of a conductor device having a Sol structure using an anti-reflection coating method according to an embodiment of the present invention, and FIG.
Figures A to 1D are plan views for explaining the manufacturing process when a seed is provided in the semiconductor device manufacturing process, and Figures 38 to 3c are antireflection films according to other embodiments of the present invention. FIGS. 4A and 4B are cross-sectional structural diagrams for explaining the manufacturing process of a semiconductor device having a Sol structure using the conventional anti-reflection film method, and show the relationship between the SO2 film formed by the conventional anti-reflection film method and crystal subgrain boundaries. Schematic diagram,
Figure 5 is a phase diagram showing the crystal state immediately after laser recrystallization in the conventional anti-reflection coating method, and Figure 6 shows the crystal state after oxidation after laser recrystallization in the conventional anti-reflection coating method. FIG. In the figure, 1 is a single crystal silicon substrate, 2 is a silicon oxide film, 3a is a polysilicon layer, 3b is a single crystal silicon film, 4 is a silicon nitride film, 5 is a seed, 10 is a resist,
11 is a resist, 12 is a silicon oxide film, 14 is an antireflection film, 20 is a crystal subgrain boundary, and 30 is a crystal defect. Note that in each figure, the same reference numerals indicate the same or corresponding parts. 11D Figure 3b-jlt Hexagram Shisokoshi n Shōjuku 2 Figure Hole 3B Figure 12 --- Shirikoshi Drama 14 Kotomo 3C Eye 5 Figure v) 6 Figure 4B Figure Procedural Amendment (Spontaneous) October 1, 1991 Japan Patent Application No. 226334 No. 2 of 1990, Person amending the name of the invention Relationship with the case Address Name Representative Method for manufacturing semiconductor devices

Claims (1)

[Scope of Claims] A method for manufacturing a semiconductor device, comprising: melting a non-single crystal semiconductor to form a molten semiconductor; forming a temperature distribution in the molten semiconductor to form a single crystal semiconductor layer on an insulating film; Recrystallization is performed after removing in advance at least a part of a region of the non-single-crystal semiconductor that corresponds to a region that should become a high-temperature part in the molten semiconductor when the non-single-crystal semiconductor is melted. A method for manufacturing a semiconductor device.