JPS58135630A - Annealing of semiconductor layer - Google Patents

Abstract

PURPOSE:To prevent penetration of infrared rays into a comparatively deep region, and to prevent destruction of a circuit element formed already in a substrate at the annealing process of the seimconductor layer according to irradiation of infrared rays by a method wherein infrared rays having the prescribed wave length or more are intercepted. CONSTITUTION:A filter 3 is provided between an infrared rays source 2 and the substrate 1 to cut the unnecessary wave length regions. The numeral 4 shows a mirror for convergency of infrared rays on the surface of the substrate. Because infrared rays cut by the filter 3 contain the wave length regions having high heating efficiency, and the temperature rise of the filter absorbing infrared rays thereof is remarkable, the filter is cooled according to the ventilation, etc., so as not to redischarge infrared rays of the long wave lengths. The filter to cut infrared rays on the long wave length side is manufactured according to the method as follows. Glass containing a metal element of a comparatively large quantity absorbs light of the wave length peculiar to the metal element thereof. Accordingly, when the filter is formed of glass containing a properly selected metal, the filter having the desired characteristic can be obtained.

Description

Detailed Description of the Invention (a') Technical Field of the Invention The present invention relates to a technique for annealing a semiconductor layer.
In particular, it relates to an annealing method performed by irradiating electromagnetic waves.

(b) Background of the Technology Annealing, which aims to remove strain existing inside bulk or layered semiconductor materials, is a technique often used in the manufacture of semiconductor devices. Refining annealing is performed by heating the entire semiconductor wafer, but if the area where strain occurs is limited to the vicinity of the surface, such as in ion implantation, it may be performed by heating only the surface with an infrared heater. .

Also, in recent years, lateral epitaxial growth has been attracting attention as a technology for realizing multilayer integrated circuits or three-dimensional integrated circuits. Although recrystallization starts from a location and affects the entire area, it is called lateral epitaxial growth because single crystallization progresses in the horizontal direction. In lateral epitaxial growth, an infrared heater is sometimes used to melt and recrystallize the non-single crystal silicon layer deposited on the surface of the substrate.

Such processing is also included in annealing technology in a broad sense.

Infrared heaters used for this purpose include carbon heaters that are resistance heating devices, arc lamps, halogen lamps, and the like.

Since it is electromagnetic waves in the infrared region that efficiently raise the temperature of the irradiated object, in the following specification, the electromagnetic waves irradiated for the purpose of annealing will be expressed as infrared light. Infrared light in this sense includes some visible light.

(C') Prior Art and Problems The carbon heaters, arc lamps, hagen lamps, etc. described above heat semiconductor layers such as non-single crystal silicon layers using the energy of infrared light emitted from the devices. Since the emitted infrared light spans a wide range of wavelengths and has different degrees of absorption in materials such as silicon and silicon dioxide layers, such light sources can be used to locate specific depths in the semiconductor substrate. It is difficult to selectively heat only those areas.

Figure 1 is a diagram showing the relationship between wavelength and the distance at which infrared light is attenuated to 1/10 in silicon, but the depth to which the light emitted from the infrared light source penetrates covers an extremely wide range. That can be read.

Therefore, when irradiating with an infrared heater to monocrystallize a polycrystalline silicon layer on the surface of a substrate on which circuit elements have already been formed, as in the case of manufacturing multilayer integrated circuits, the infrared rays penetrate into the inside of the substrate. The light also heats already formed circuit elements, causing their properties to change significantly.

(d.) Purpose of the invention The purpose of the present invention is to use irradiation to heat the substrate surface.

An object of the present invention is to provide an infrared heating method that prevents infrared light from entering a relatively deep region and does not destroy circuit elements already formed in a substrate.

(e) Structure of the Invention In the semiconductor layer annealing method of the present invention, in the step of annealing the semiconductor layer by irradiating infrared light, a predetermined wave XJJ of the infrared light generated from the infrared light source is blocks infrared light,
The semiconductor layer is irradiated with infrared light having a wavelength shorter than the predetermined wavelength.

(f) Embodiment of the Invention When the target of annealing is silicon, and the thickness of the target layer is lpm, as is clear from FIG.
When infrared light with a wavelength longer than μm passes through the target layer and enters, it may form an image. Therefore, if the infrared light in this region is cut by some method, the irradiated energy will be exposed. Most of it is absorbed in the range of 115m, and the temperature rise in deeper regions is small.

From this point of view, in this koji shoulder, as shown in FIG. 2, a filter 3 is provided at the threshold between the infrared light source 2 and the substrate 1 to cut out unnecessary wavelength regions. 4 is a mirror for converging infrared light onto the substrate surface.

The infrared light cut by the filter 3 includes a wavelength range with high heating effect, so the temperature of the filter that absorbs it will rise significantly. It is necessary to forcibly cool it down.

A filter that cuts infrared light on the long wavelength side can be created using the following method.

Glass containing a relatively large amount of metal elements absorbs light at wavelengths specific to the metal elements. Therefore, by manufacturing a glass containing a plurality of appropriately selected types of 7C1l and forming a filter using the glass, a filter having desired characteristics can be obtained. Furthermore, it is effective to use a metal mesh to cut out the longer wavelength side.

In the above example, wavelengths of 0.5 μm or more are cut, but this naturally varies depending on the material and thickness of the layer to be heated, and the characteristics of the filter used may also vary accordingly7.

(g) Effects of the Invention and More As described above, according to the present invention, when annealing the semiconductor layer on the surface of the substrate, the temperature of the internal region of the substrate is not increased more than necessary, so that the condition inside the substrate is maintained. Annealing of the surface layer can be performed without significantly changing the surface layer.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between the attenuation distance and wavelength of infrared light in silicon, and Fig. 2 is a diagram showing an example of this g&-, in which 1 is the substrate, 2 is the An infrared light source, 3 a filter, and 4 a mirror.

Claims (1)

[Claims] In the process of annealing the semiconductor layer by irradiating electromagnetic waves,
A method for annealing a semiconductor layer, which comprises rejecting electromagnetic waves having a predetermined wavelength or more among electromagnetic waves generated from an electromagnetic wave generation source, and irradiating the semiconductor layer with electromagnetic waves having a wavelength shorter than the predetermined wavelength.