JPS60186496A - Production of semiconductor device - Google Patents

Abstract

PURPOSE:To produce a single crystal thin film of good quality in a nonsingle crystal region, by forming a nonsingle crystal thin film on a substrate, applying a thin antireflection film thereto, forming a film having light absorption properties of smaller width than the diameter of energy beams, and irradiating the film with the energy beams. CONSTITUTION:A polycrystal silicon thin film 5 having light absorption properties is formed on a ground insulating substrate 1, and a laminated antireflection film 6, e.g. SiO2 or Si3N4, is formed further on the resultant thin film 5. A light- shielding polycrystal silicon film 7 having light absorption properties of smaller width than the diameter of laser beams 8 is formed thereon. The resultant construction is irradiated with the laser beams 8, which are incident upon a part 51 uncoated with the light shielding polycrystal silicon film 7 to increase the temperature, and the light-shielding film 7 coating the part 52 absorbs the laser beams 8 to increase the temperature and conduct the temperature through the SiO2 film 6. Thus, the temperature distribution is such that the central part 52 of the polycrystal silicon film 5 is low and the periphery is high. Nuclei are formed in the central part 52, and grow to form the aimed single crystal thin film.

Description

[Detailed Description of the Invention] Technical 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 which the grain size of a thin film crystal is expanded by recrystallization by irradiation with an energy beam such as a laser beam. This relates to a manufacturing method.

<Prior Art> In recent years, research has been conducted into converting a non-single crystal thin film formed as a polycrystalline or amorphous thin film into a single crystal and using it as a semiconductor substrate. In other words, energy is applied to a non-single crystal thin film using a laser beam or the like to melt it, and when this melted region is solidified, crystal grains are grown to form a single crystal. It is a diagram showing the manufacturing process.

In the figure, an insulating substrate 1 made of a material such as quartz or silicon is used as a support base, and a light-shielding polycrystalline material is coated on the surface of the substrate 1 with a heat-absorbing property, that is, a light-shielding polycrystal that has the effect of blocking heat conduction to the substrate 1. A silicon film 2 is deposited, and a polycrystalline silicon region 4 for single crystallization is formed on the polycrystalline silicon film 2 at 5I.
It is formed in the form of an island embedded in the insulating film 3 made of O2, 813N4, etc. The substrate having the laminated structure is irradiated with a laser beam to provide energy for monocrystallizing the polycrystalline silicon region 4.

In the above substrate structure, the substrate in which the island-shaped polycrystalline silicon region 4 is buried is an Si02 insulating film 3 that has a strong antireflection effect and transmits incident light, and the laser light that has passed through the insulating film 3 is absorbed by the absorbing material. It reaches the polycrystalline silicon film 2 and is directly absorbed, causing the temperature of @2 to rise. The base polycrystalline silicon film 2 rises in temperature -J- in a double series, and this heat is conducted to the island-like polycrystalline silicon region 4, so the temperature distribution in the region 4 is as shown by curve A in FIG. As shown, the periphery of region 4 is higher than the center, and assimilation during recrystallization proceeds from the center B in a low temperature state, forming region 4 as a single crystal.

In the substrate structure according to the conventional manufacturing method, the 5i02 film 3 burying the island-shaped polycrystalline silicon region 4 has an I/m
When a thick film is formed,
It is extremely difficult to prevent variations during film formation in the actual thin film formation process. This kind of film thickness variation is 5
This has a large effect on the fouling rate of the 102 film 3, and this change in reflectance affects the amount of laser light absorbed by the light-shielding polycrystalline silicon film 2 formed as a base. Island-shaped polycrystalline silicon region 4
receives heat conduction from the polycrystalline silicon film 2, so variations in the film thickness of the 5i02 film 3 as described in section 2 will make the temperature distribution in the region 4 unstable, and this will cause the formation of the recrystallized silicon film. This causes variations in crystallinity, making it undesirable as a semiconductor substrate.

Furthermore, in the above substrate structure, since the single crystal region is formed in an island-like structure buried in the insulating film, a separation width between the gaps is required, which increases the effective area of the crystal.

<Objective of the Invention> The present invention provides a manufacturing method capable of eliminating the drawbacks of the conventional semiconductor device manufacturing methods described above and capable of stably recrystallizing a non-single crystal thin film into a single crystal region.

<Example> In this example, a non-single crystal thin film for single crystallization is covered with a thin insulating film that acts as an antireflection film, and a stripe is further formed in the area to be single crystallized, especially near the nucleation part. A substrate is created by laminating light absorbing layers in the shape of a shape, and by irradiating the substrate with an energy beam, the part of the non-single crystal thin film that is not covered with the light absorbing layer is directly heated. The deposited light absorption layer absorbs energy for the non-single-crystalline thin film, and the resulting heat is conducted to heat the thin film and create an optimal temperature distribution for recrystallization.

In FIG. 1, a thin film 5 for single crystallization is deposited on an underlying insulating substrate 1 using a light-absorbing polycrystalline silicon or amorphous silicon film. Further on the thin film 5 are 5iQ2.5i3N4 or 5i02 and 5iBN4.
A laminated film 6 is formed as an antireflection film, and a light-shielding polycrystalline silicon film 7 is formed overlyingly by chemical vapor deposition. The polycrystalline silicon film 7 has a light-shielding property, that is, a light-absorbing property, and absorbs the irradiated laser light, thereby increasing the temperature of the polycrystalline silicon film 7 itself. Therefore, the polycrystalline silicon film 7 suppresses temperature rise with respect to the non-single crystal thin film 5 and provides nucleation during the recrystallization process. Therefore, the polycrystalline silicon film 7
is patterned into a stripe shape taking into account the size of the single crystal region to be created, and the width of the stripe is set to be smaller than the width of annealing performed with an energy light source such as a laser beam or lamp. directly heats the polycrystalline silicon film 5.

A light-shielding or light-absorbing film 7 covering the single crystallized region of the thin film 5
can be formed using the same material as the polycrystalline silicon film 5 as described above, but it can also be formed using other film materials, and the film thickness is such that almost 100% of the light is absorbed within the film. Set to thickness.

The film thickness of 5iO26 as the anti-reflection film covering the thin film 5 is desirably selected to a value that provides the lowest reflectance in order to increase the absorption rate of light emitted from the light source such as a laser or lamp as an energy source. 900 and 2600 when using an argon laser as the energy source.

900A because the lower polycrystalline silicon film 5 melts due to the heat generated in the light shielding film 7.
The value of is optimal. The 5i02 film 6 is formed by chemical vapor deposition, etc., but at a relatively thin film thickness such as the above value, even if there is a variation in the film thickness distribution of about ±10fo, the reflectance will be a few percent. only changes. Therefore, when producing a substrate having the above-described laminated structure, variations in film thickness distribution during production have little effect on crystallinity, and a thin film with uniform crystallinity can be produced.

That is, in FIG. 3, a light shielding film 7 is provided on the substrate with the above-mentioned laminated structure.
When the laser beam 8 is irradiated so that the beam center of the laser beam is located at the center of The laser beam 8 is incident on the area, and the temperature of that area increases. On the other hand, in the portion 52 covered by the light-shielding film 7, the laser beam is absorbed by the light-shielding film 7 and the temperature of the light-shielding film 7 rises, and the heat passes through the 5IO2 film 6 to the polycrystalline silicon film 5.
conducted to. At this time, at 5 degrees directly below the light shielding film 7, due to the reflection from the light shielding film surface and the temperature drop due to the Sio2 film 6,
The temperature rise in the periphery or area boundary 51 is high, as shown by curve C in FIG.
A temperature distribution where the surrounding area is high is formed.

In the second temperature distribution, nuclei are generated in the central region 52 during the solidification process from the liquid phase, and these nuclei grow to form a single crystal thin film.

After being made into a single crystal by the above annealing treatment, the light shielding film 7,
The antireflection film 6 is removed by etching, and the single crystal region is processed by photolithography into a shape suitable for fabricating a semiconductor device.

FIG. 4 shows multiple single crystal regions 5.
5... are shown adjacent to each other, light shielding films 7, 7... similar to those in the above embodiment are repeatedly formed in correspondence with the annealing width of the laser beam 8, and on each light shielding film 7. Laser light 8 is irradiated to recrystallize thin film 5 into stripes.

Since each single crystal region is formed with an arbitrary orientation,
A grain boundary is generated at the boundary between the double-headed regions. According to this method, each single-crystal region can be single-crystalized in a stripe pattern over the entire surface without having to use a separation width as in the conventional method.

In addition, when the light shielding film 7 is made of a material with a large refractive index and high reflectance, the surface of the light shielding film 7 is also coated with an antireflection film 8.
102 etc. can be laminated to adjust the reflectance.

Effect> As described above, according to the present invention, when recrystallizing a thin film by annealing it with an energy beam, it is possible to create a thin film that is affected by variations in film thickness distribution when creating each thin film having a laminated structure. Moreover, the effective area by recrystallization can be increased.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a substrate for explaining an embodiment according to the present invention, FIG. 2 is a temperature distribution diagram during an annealing process, and FIG. 3 is a diagram for explaining a recrystallization process of an embodiment according to the present invention. FIG. 4 is a sectional view of a substrate for explaining another embodiment of the present invention, and FIG. 5 is a sectional view of a substrate for explaining a conventional manufacturing method. 1: Insulating substrate, 5: Polycrystalline silicon film, 6: Antireflection film, 7: Light shielding film, 8: Laser light. Agent Patent attorney Aihiko Fuku (2 others) 1L21 Figure 2 Figure 3

Claims (1)

[Claims] 1) In a method of manufacturing a thin film crystal by recrystallizing a light-absorbing non-single crystal thin film by annealing with an energy beam, a thin anti-opposition film is formed on the non-single crystal thin film with a width smaller than the energy beam diameter. A semiconductor characterized by forming a light-absorbing film and irradiating an energy beam over the film, and growing crystals using seeds generated in a non-single-crystal region covered by the film. Method of manufacturing the device.