JPS62257718A - Solid phase epitaxy of semiconductor thin film - Google Patents

Abstract

PURPOSE:To enable a solid phase epitaxial region to be formed at any position as required, by applying energy beams to a region having a smaller area than that of the solid phase epitaxial region while moving the energy beam applied region. CONSTITUTION:Insulation films 2, 2... are formed selectively on the surface of a wafer-type semiconductor substrate 1. A silicon semiconductor layer 4 is deposited over the whole surface of the substrate 1. A region 4a of the semiconductor layer 4 located on an exposed region 3 of the substrate 3, including its peripheral region, is heated by laser beams. Thereby, the solid phase epitaxy is started from the exposed region 3 of the substrate 1 and extended to the region 4a. The semiconductor layer 4 is then irradiated, in its broad region 4b including the irradiated region 4a and a peripheral region extending around it, with laser beams and heated thereby, During this process, the epitaxial region can be further extended from the region 4a to the region 4b. The position and configuration of the extended epitaxial region can be selected as required by controlling the region irradiated with laser beams.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Industrial field of application B1 Overview of the invention C1 Prior art [Figure 4] B1 Problems to be solved by the invention [Figure 4] E9 Means for solving the problems F1 Effects G. Examples [Figure 4] 1 to 3] H0 Effects of the Invention (A, Industrial Application Field) The present invention relates to a method for solid-phase epitaxial growth of semiconductor thin films.

(B. Summary of the Invention) The present invention provides a method for selectively forming a solid-phase epitaxial region on a substrate in a solid-phase epitaxial growth method for a semiconductor thin film, and for improving the lateral extension of the solid-phase epitaxial region. .

The energy having a larger cross-sectional area than the area where solid-phase epitaxy is to be formed in the semiconductor layer on the substrate is made to have a smaller cross-sectional area than the area where solid-phase epitaxy is to be formed by the irradiation area regulating means, and the irradiated area is moved. According to the solid-phase epitaxy cell growth method of a semiconductor thin film of the present invention, the solid-phase epitaxy cell growth method of the present invention is achieved by moving the irradiation region of the above energy from the part of the semiconductor layer in contact with the seed to an arbitrary region. A wide epitaxial region can be formed at an arbitrary position.

(C, Prior Art) [Fig. 4] As shown in Fig. 4, an insulating film is partially formed on the surface of a silicon semiconductor substrate a (the surface is, for example, a (100) plane), and the insulating film is There is a technique that attempts to form an Evitacal growth layer C on the semiconductor substrate a including the top. The epitaxy of this epitaxy-grown layer C gradually spreads onto the insulating film from the exposed portion of the semiconductor substrate a.

(D. Problem to be Solved by the Invention) [Fig. 4] By the way, conventionally, when forming the semiconductor layer C, the entire surface portion of the semiconductor substrate a is heated within at least one element formation sphere. Therefore, a large number of epitaxy nuclei are randomly generated on the insulating film, and a polycrystalline region e is formed. As a result, the length of the portion where the epitaxial region d, which is generated using the exposed portion of the semiconductor substrate a as a seed, extends from the exposed portion of the semiconductor substrate a onto the insulating film is only about 4 to 5 microns, and epitaxy is obtained on the insulating film. It has been difficult to make the entire region where this is required an epitaxial region.

The present invention was made to solve such problems,
It is possible to selectively form an in-phase epitaxial region with good uniformity and reproducibility.

Another purpose is to increase the length of the solid phase epitaxial region extending over the insulating film.

(E. Means for Solving Problems) The solid-phase epitaxial growth method of the semiconductor FJ film of the present invention uses energy having a larger cross-sectional area than the area where solid-phase epitaxy of the semiconductor layer on the substrate is to be formed. The present invention is characterized in that the cross-sectional area is made smaller than the area where solid phase epitaxy is to be formed, and the energy irradiation area is moved.

(F. Effect) According to the solid-phase epitaxial growth method of a semiconductor thin film of the present invention, the energy irradiation area is made smaller than the solid-phase epitaxial region by the irradiation area regulating means and the irradiation area is moved, so that the irradiation area is moved to the semiconductor layer. By moving the non-epitaxial region from the part in contact with the seed to any region of the non-epitaxial region, the non-epitaxial region can be converted into an epitaxial cell. Therefore, the solid phase epitaxial region can be formed in any desired region of the semiconductor layer, and the solid phase epitaxial region can extend more widely in the lateral direction.

(G, Example) [Figures 1 to 3 1 Hereinafter, the present invention will be explained according to illustrated embodiments.

(a. Manufacturing method) [Fig. 1] Fig. 1 (A) to (C) show one embodiment of the present invention in the order of steps.

(A) Insulating films 2.2, . . . are selectively formed on the surface of a wafer-shaped semiconductor substrate (for example, the surface is (100) plane). 3 is an exposed portion of the semiconductor substrate l. Thereafter, a silicon semiconductor layer CHI (thickness, for example, 1000 angstroms) 4 is deposited over the entire surface of the semiconductor substrate l. This semiconductor layer 4 becomes an amorphous state. FIG. 1(A) shows the state after the silicon semiconductor layer 4 is formed.

(B) Next, using the apparatus shown in FIG. 2 (described later), the semiconductor layer 4 is partially heated with a laser beam to cause solid phase growth as shown in FIG. 1(B). In this step, the laser beam partially heats the portion of the semiconductor layer 4 located on the exposed portion of the semiconductor substrate l (which serves as the seed for solid phase growth) and the region 4a around it. Solid phase epitaxy spreads to the heated portion 4a of the semiconductor layer 4 using the exposed portion 3 of the semiconductor substrate 1 as a seed.

It is preferable that @d' of the area to be irradiated in this step be made slightly wider than the width d of the exposed portion of the semiconductor substrate 1 (as wide as not more than 4 to 5 microns away from the seed portion).

(C) Next, as shown in FIG. 1(C), the irradiation area 4 is
The semiconductor layer 4 is heated by irradiating it with a laser beam over a wide region 4b that includes the irradiation region 4a and extends around the irradiation region 4a.

This step allows the epitaxial region 4a formed in the step of FIG. 1(B) to be further expanded to 4b. And the position where the epitaxial region is expanded,
The shape etc. can be arbitrarily selected by controlling the area irradiated with the laser beam.

(b, Apparatus) [FIGS. 2 and 3] FIG. 2 is a schematic diagram showing an example of a growth apparatus used for carrying out the solid phase epitaxial growth method of a semiconductor thin film of the present invention.

1'F=l[1, 5 is an excimer laser, 6 is a beam shaper that shapes the cross-sectional shape and energy distribution of the laser beam output from the excimer laser 5; The cross-sectional shape is approximately rectangular, and the energy distribution is approximately uniform. 7 is a mirror that reflects the laser beam from the beam shaper 6 and changes its direction; 8 is a mirror that cuts energy above a predetermined level so that the energy distribution of the laser beam reflected by the mirror 7 becomes a clean pulse shape. An integrator, 9 is a condenser lens, and 1O is a reticle that serves as a mask for selectively irradiating the surface of the substrate 1 with a laser beam. A reticle loa with a different mask pattern depending on the process.

10b (see Figure 3) is used. Reference numeral 11 denotes a reduction projection lens 11 for projecting the mask pattern of the reticle 10 onto the substrate l by reducing it to a fraction of the original size. An irradiation area regulating means is configured, and an arbitrary area on the surface of the wafer-shaped semiconductor substrate 1 in the chamber 12 can be selectively irradiated by the irradiation area regulating means.

3(A) and 3(B) show examples of reticles 10a and 10b used in carrying out the method of the present invention, and FIG. 3(A) shows a reticle used as a mask during the first laser beam irradiation, and FIG. (B) is the reticle used as a mask during the second laser beam irradiation, and 13a is the reticle shown in FIG.
A beam transmitting section 13b passes the laser beam toward the irradiation area 4a shown in B), and a beam transmitting section 13b passes the laser beam toward the irradiation area 4b shown in FIG. 2(C). and,
The width of the beam transmission section 13a of the first reticle 10a is equal to the width d' of the irradiation area 4a multiplied by the reciprocal of the reduction ratio, and the width of the beam transmission section 13b of the second reticle 10b is the width of the irradiation area 4b. The width is the reciprocal of the reduction ratio.

With such an apparatus, the surface of the substrate 1 can be selectively and sufficiently heated with a laser beam having an intensity of 200 millijoules/cm' to perform solid-phase epitaxial growth.

It should be noted that the laser beam irradiation with different widths of the irradiation area may be performed not by changing the reticle but by changing the projection reduction ratio. Instead of expanding the taxial region, selective solid phase epitaxy growth may be performed by laser beam irradiation more times than each.

Further, as in the above embodiment, the portion in contact with the exposed portion 3 of the semiconductor substrate 1 which is the seed of the silicon semiconductor layer 4 and its vicinity are first heated with a laser beam to achieve solid phase epitaxial growth, and then the second layer is heated. The epitaxy may be spread to the periphery (four sides) by the laser beam heating for the second time, but the epitaxy may be spread in one direction instead of the periphery. In short, any method may be used as long as solid phase epitaxy is achieved by moving the irradiation area, and the direction of movement of the irradiation area is not particularly limited.

Furthermore, in the above embodiment, after depositing the silicon semiconductor layer 4 in advance, solid phase epitaxy is performed in the chamber 12 as described above, and in this way, ion implantation of St cations is possible. However, the wafer-shaped semiconductor substrate 1 is placed in the chamber 12 without debossing the silicon semiconductor layer 4.
After cleaning the silicon surface, the semiconductor layer 4 may be grown by photochemical CVD, plasma CVD, etc., and then solid-phase epitaxy may be performed using a laser beam.

The present invention can be applied to solid phase growth of epitaxy by annealing, selective vapor phase epitaxial growth, etc. (H, Effects of the Invention) As is clear from the above description, the solid phase epitaxial growth method for semiconductor thin films of the present invention can be applied to The energy having a substantially uniform energy distribution over a large area is regulated by the irradiation area regulating means to a smaller area than the region where solid phase epitaxy is to be formed in the upper semiconductor layer, and the irradiation The feature is to move the area.

Therefore, according to the solid phase epitaxial growth method of a semiconductor a film of the present invention, the irradiation area with uniform energy distribution is made smaller than the solid phase epitaxial area by the irradiation area regulating means and the irradiation area is moved. By moving the region from the portion of the semiconductor layer in contact with the seed to any region of the non-epitaxial region, the non-epitaxial region can be made into an epitaxial region. Therefore, the solid phase epitaxial region can be formed in an arbitrary region of the semiconductor layer, and the extension of the solid phase epitaxial region in the lateral direction can be made larger.

[Brief explanation of drawings]

1 to 3 are for explaining an embodiment of the solid-phase epitaxial growth method for a semiconductor thin film of the present invention, and FIGS. 1(A) to 3(C) illustrate the growth method on a substrate shown in step j@. A cross-sectional view, FIG. 2 is a schematic diagram of the growth apparatus, and FIG. 3 (A), (
B) is a plan view showing different reticles used for regulating the irradiation area, and FIG. 4 is a sectional view for explaining the prior art and its problems. Explanation of symbols: 1-bottle/substrate, 4-concept-semiconductor layer. 4a, 4bΦ...irradiation area, 9-11...O irradiation area regulating means. CB) (C) Cross-sectional diagram showing the large force Te J to Niobm Fig. 1 Bottom & device schematic diagram Fig. 2 Fig. 1f Lujiful (A> Fig. 3

Claims (1)

[Claims] (1) The energy having a substantially uniform energy distribution over an area larger than the area where solid phase epitaxy is to be formed in the semiconductor layer on the substrate is restricted to an area smaller than the area where solid phase epitaxy is to be formed by the irradiation area regulating means. , A method for solid-phase epitaxial growth of semiconductor thin films, characterized by moving the irradiation area.