JPS6233418A - Band melting type single crystal semiconductor layer forming device - Google Patents

Abstract

PURPOSE:To form a single crystal semiconductor with large space and high quality by a method wherein, when a band melting region of sample is moving, the temperature in the front region connecting with the band region is controlled to be higher than the temperature in the rear region connecting with the band region. CONSTITUTION:A position sensor 21 is provided on one side of a wafer support 14 to detect the relative position thereof to the moving band melting region of a sample wafer 30. A controller 20 controls the power supply for each substrate heating tubularlamp 19a-19j below the rear region connecting with the band melting region to be lower than the power supply for each substrate heating tubularlamp below the front region connecting with the band melting region according to the outputs from the position sensor 21. Through these procedures, the temperature distribution of sample wafer 30 in the scanning direction can be controlled so that the temperature in the front region connecting with the band melting region may be higher than the temperature in the rear region.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a zone melting type single crystal semiconductor layer forming apparatus,
In particular, it relates to a zone melting type single crystal semiconductor layer forming apparatus that can manufacture a high quality single crystal layer with a relatively large area by recrystallizing a polycrystalline or amorphous semiconductor layer on an insulating layer. It is.

[Prior Art] A conventionally used zone melting type single crystal semiconductor layer forming apparatus will be described with reference to FIG. 3. In the figure, reference numeral 1 refers to a sample wafer 3, which will be described later, which is heated from the bottom surface.

A plate-shaped lower heater made of carbon or the like configured to raise the temperature, 2 also heats the sample wafer 3 from above;
This is a linear upper heater configured to raise the temperature and move at a very slow speed from one end to the other end. An arrow 5 indicates the direction of movement of the upper heater 2. The sample wafer 3 also has a polycrystalline silicon layer to be melted and recrystallized. As shown in FIG. 4, this sample wafer 3 has a silicon dioxide layer 7 about 0.5 μm thick formed on the whole surface of a single-crystal silicon substrate 6, and is melted and recrystallized on that surface. 0.5 μl of polycrystalline silicon @8
l18! It is formed to have a thickness of 100 degrees. Further, on the surface of the polycrystalline silicon layer 8, a 2 μm thick silicon dioxide layer is formed as a protective layer to prevent this polycrystalline silicon layer from peeling off from the single crystal silicon substrate 6 during melting.
A silicon nitride layer 10 having a thickness of approximately nm is laminated.

Therefore, in order to recrystallize the polycrystalline silicon@8 in the sample wafer 3 into a single crystal, the sample wafer 3 is heated using the lower heater 1.
is heated to 1200℃ from the bottom side.

Increase temperature. Then, while raising the temperature of the upper heater 2 to 2000° C., the upper heater 2 is heated to 100° C. from the upper surface of the sample wafer 3.
The entire area of the sample wafer 3 is scanned by moving the sample wafer 3 by approximately 2 mlN from one end in a fixed direction shown by the arrow 5, for example, at a rate of 2 ml/sec. At this time, sample wafer 3
A molten layer 4 corresponding to the shape of the upper heater 2 is formed inside, and as this moves as the upper heater 2 moves,
Large crystal grains of the polycrystalline silicon layer 8 in the sample wafer 3 will be achieved. Note that this growth is performed in an inert gas atmosphere such as argon.

FIG. 5 is a diagram showing a zone melting type single crystal semiconductor layer forming apparatus, which is another example of the prior art.

In the figure, this device generally includes the lower heater 1. of FIG.
The upper heater 2 is replaced with a plurality of MW heating tubular lamps 11a to 11e and a melt forming tubular lamp 12, respectively. To explain in detail, a sample wafer 3 having a structure similar to that shown in FIG. 4 is placed on the wafer holding plate 14.
o is placed.

A tubular lamp 12 for forming a melt is provided above the sample wafer 30 and has a condensing mirror 120 parallel to the upper surface. The condensing mirror 120 is a tubular lamp 1 for forming a melt.
The sample wafer 30 is heated by condensed light from the sample wafer 2, and the polycrystalline silicon layer is melted in a band shape. Also,
At the bottom of the wafer holding plate 14, a plurality of annular lamps 11a to 11e for substrate heating are provided in parallel to the lower surface of the wafer holding plate.
are provided, and each substrate heating tubular lamp lla~1 is provided.
1e has reflective mirrors 110a to 110e, respectively. The tube axes of the substrate heating tubular lamps 11a to 11e are arranged parallel to the tube axis of the melt forming tubular lamp 12 and at equal intervals. Each reflective mirror 1
10a to 110e are tubular lamps 1 for heating each substrate, respectively.
The light from the substrate heating tubular lamps 11a to 11e that prevents the scattering of light from 1a to 11e irradiates the entire lower surface of the A holding plate 14 and heats it, thereby heating the single crystal of the sample wafer 3o. heating the silicon substrate.

In this apparatus, the number of heat tubular lamps 110 is relatively large in order to uniformly heat the single crystal silicon substrate of the sample wafer 3o. The sample urchin l\30 is moved along with the substrate heating tubular lamps 11a to 11e in the direction of the arrow 15 relative to the melt forming tubular lamp 12, and the sample wafer 30 is irradiated with light from the melt forming tubular lamp 12. while scanning the entire area. At this time, the belt-shaped melted region is moved between the silicon dioxide 1 above and below it, and in this way the polycrystalline silicon layer of the sample wafer 30 is recrystallized to become a single crystal.

Further, as described above, in order to uniformly heat the silicon substrate of the sample wafer, an apparatus has also been provided in which the number of tubular lamps for heating the substrate is limited to one.

[Problems to be Solved by the Invention] The conventional zone melting type single crystal semiconductor layer forming apparatus is configured as described above, and can heat the single crystal silicon substrate of the sample wafer sufficiently uniformly. Such consideration was given. However, when band melting is actually performed using conventional equipment, the sample wafer is heated from both its top and bottom surfaces, which makes it difficult for heat to escape from the center of the sample wafer, resulting in a phenomenon in which the melting conditions at the center and the periphery differ. However, there was a problem in that no matter how designed, a large area sample wafer with a diameter of 4 inches or more could not be recrystallized by band melting by one scan.

In addition, even if the heating concentration was adjusted so that only a part of the center of the sample wafer could be melted, the latent heat of solidification from melting to solid state could not be sufficiently dissipated, and the temperature gradient related to crystal growth would become gentle. A phenomenon occurs in which the crystal growth plane is not perpendicular to the direction of progress of zone melting. This phenomenon will be explained in more detail with reference to FIGS. 6(A) and 6(B). FIG. 6(A) is a cross-sectional view of the sample wafer during zone melting, and FIG. 6(B) is a plan view including the polycrystalline silicon layer of FIG. 6(A). This is a belt-shaped melted region of the polycrystalline silicon layer 8 caused by the lamp light 13;
1 is a single crystal silicon layer. When the concentration gradient related to crystal growth becomes gentle, the crystal growth surface 16 becomes <111
> surface, resulting in a sawtooth-like appearance. For this reason, 17
There is a problem in that the crystal grain boundaries 18 are generated although the tilt angle is small due to impurity precipitation and stress increase in locations such as , and the polycrystalline silicon layer cannot become a single crystal over the entire surface.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a zone melting type single crystal semiconductor layer forming apparatus that can form a large area and high quality single crystal semiconductor layer. shall be.

[Means for solving the problems] The zone melting type single crystal semiconductor layer forming apparatus according to the present invention includes:
A sample including an insulating layer and a polycrystalline or amorphous semiconductor layer formed on the insulating layer is placed on a stand, and the sample is irradiated and heated parallel to and apart from the top surface of the sample to form the semiconductor layer into a band shape. A first elongated radiant heating source for melting the sample is provided, a second radiant heating source for irradiating and heating the sample is provided parallel to and separated from the lower surface of the table and fixedly relative to this table, and a second elongated radiant heating source is provided for irradiating and heating the sample by moving means The radiant heating source is moved relative to the first longitudinal radiant heating source in a direction substantially perpendicular to the longitudinal direction of the first longitudinal radiant heating source to move a band-shaped melting region over the insulating layer; Melt! !
When the region is transferred, the heating of the second radiant heating source is controlled by the heat control means so as to increase the concentration of the front region following the belt-shaped melting region and lower the temperature of the rear region following the belt-shaped melting region. It was designed to be controlled.

[Function] In the present invention, in the movement of the band-shaped melted region of the sample,
The temperature is controlled to be high in the front region following the belt-like melting region and to lower the temperature in the rear region following the belt-like melting region.
Band melt! ! The temperature gradient at the solid-liquid interface at the trailing edge of the region increases.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a zone melting type single crystal semiconductor layer forming apparatus according to an embodiment of the present invention. To explain the configuration of this device, in the figure, the wafer holding plate 14 is made of carbon, and its thickness is 611 Im to 10111 Im. Make the shape square or rectangular. Wafer holding plate 1
A sample wafer 3o is placed on top of the sample wafer 4. This sample wafer is
It has the same structure as the sample wafer shown in FIG. That is, a silicon dioxide layer, a polycrystalline silicon layer, a silicon dioxide layer, and a silicon nitride layer are laminated in this order on a single-crystal silicon substrate, and the polycrystalline silicon layer to be made into a single crystal is formed within an insulating layer. is sandwiched between.

A tubular lamp 12 for forming a melt is provided above the sample wafer 30 and has a condensing mirror 120 parallel to the upper surface. The condensing mirror 120 is a tubular lamp 1 for forming a melt.
Two beams of light are condensed onto the sample wafer at 3° to heat it, and the polycrystalline silicon layer is melted in a strip between the upper and lower insulating layers. Further, at the bottom of the wafer holding plate 14, there are ten lamps parallel to the lower surface of the wafer holding plate and parallel to the tube axis of the tubular lamp 12 for forming the melt. Housing lamp 1 for heating S plate
9a to 19j are installed closely spaced apart from each other. The light from the daytime temporary heating tubular lamps 19a to 19j illuminates and heats the entire lower surface of the wafer holding plate 14, thereby heating the single crystal silicon substrate of the sample wafer 30. The substrate heating tubular lamps 19a to 19J and the wafer holding plate 14 are fixed to each other, and the transfer gtJ
The apparatus (not shown) moves the wafer holding plate 14 on which the sample wafer 30 is placed and the substrate heating tubular lamps 19a to 19j in the direction of an arrow 1 substantially perpendicular to the tube axis of the melt forming tubular lamp 12.
It is moved in five directions relative to the tubular lamp 12 for forming the melt. As a result, the entire area of the sample wafer 30 is scanned while being irradiated with light from the melt forming tubular lamp 12, and the belt-shaped r8 melting region of the polycrystalline silicon layer is moved in the scanning direction between the upper and lower insulating layers. . Wafer holding plate 14
A position sensor 21 is provided on the side of the sample wafer 30, which detects the position of the moving belt-shaped melting region with respect to the sample wafer 30. The position sensor 21 is connected to a subsidiary device 20, which control device 20 controls each substrate heating tubular lamp 19.
connected to a to 19j. The control device 2o includes a power supply, supplies power to each of the substrate heating tubular lamps 19a to 19J, and controls the power supplied to each substrate heating tubular lamp based on the output of the position sensor 21, thereby controlling the sample wafer. Control the temperature distribution of 3o.

Next, the case where zone melting is performed using this apparatus will be explained. The entire lower surface of the wafer holding plate 14 is irradiated and heated with light from the substrate heating tubular lamps 19a to 19j, and the upper surface of the sample wafer 30 is irradiated and heated with light from the melt forming tubular lamp 12. In this state, the wafer holding plate 14 on which the sample wafer 30 is placed is moved along with the substrate heating tubular lamps 19a to 19j by the moving device in the direction of arrow 15, which is approximately perpendicular to the tube axis of the melt forming tubular lamp 12. It is moved relative to the lamp 12. At this time, the sample wafer 3o is scanned while being irradiated with light from the melt-forming tubular lamp 12, and a band-shaped melted region of the polycrystalline silicon layer with a width of about 2IllII is created between the insulating layers of the sample wafer 3o, and this melted region is The sample wafer 30 is moved from one end of the sample wafer 30 to the other end between the insulating layers while causing crystal growth at its trailing edge. At this time, the position of the belt-shaped melted region with respect to the sample wafer 30 is detected by the position sensor 21, and based on the output of this position sensor 21, the control I device 2o
According to the movement of the belt-shaped melting region, the power supplied to each substrate heating tubular lamp under the rear wta following the belt-shaped melting region is lower than the power supplied to each substrate heating tubular lamp under the front region following the belt-shaped melting region. As a result, the temperature distribution in the scanning direction of the sample wafer 3° is controlled such that the temperature in the front region following the belt-shaped melting region is high, and the temperature in the rear region following the belt-shaped melting region is low. Ru. That is, as shown in FIG. At this time, the temperature distribution of the sample wafer 30 in the scanning direction is controlled to be lower than the power supplied to the substrate heating tubular lamps 196 to 19J, as shown in FIG. 1r!120 of the front region following the belt-shaped melting region on M temporary heating tubular lamps 19a to 19c is controlled so that the temperature 21 of the rear fiI strip following the belt-shaped melting region on M temporary heating tubular lamps 19a to 19c is lowered. Therefore, the temperature gradient associated with recrystallization at the trailing edge of the band-shaped groove region becomes steeper, and factors that hinder heat radiation, such as discharging latent heat of solidification, are removed, and the crystal growth plane becomes a plane perpendicular to the scanning direction.
Easily forms a large-area, high-quality single-crystal silicon layer on a silicon dioxide layer with less segregation of impurities.
can do.

In the above embodiment, a case is shown in which a plurality of tubular lamps are used to heat the substrate, but the substrate may be heated using a plurality of linear heaters. The substrate may be heated using a linear arc torch as a cathode, and in these cases, the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, a case where a polycrystalline silicon layer is made into a single crystal is shown, but the layer to be made into a single crystal may be another polycrystalline semiconductor layer or an amorphous semiconductor layer, and in this case, This embodiment also has the same effect as the above embodiment.

Further, in the above embodiment, the case where the polycrystalline silicon layer on the silicon dioxide layer is crystallized is shown, but the polycrystalline silicon layer on the other insulating layer may be made into a single crystal. The same effects as in the embodiment are achieved.

Furthermore, in the above embodiment, the temperature distribution of the sample wafer is controlled by controlling the power supplied to the tubular lamp for heating the substrate. The heat insulating material is fixedly provided to the band-forming tubular lamp, and is inserted between the wafer holding plate and the substrate heating tubular lamp so as to correspond to the rear area following the band-shaped melting area of the sample. The temperature of the sample wafer may also be controlled.

[Effects of the Invention] As described above, according to the present invention, a sample including an insulating layer and a polycrystalline or amorphous semiconductor layer formed on the insulating layer is placed on a stand, and the sample is placed parallel to the upper surface of the sample. A first longitudinal radiant heating source is provided to irradiate and heat the sample to melt the semiconductor layer in a band shape, and irradiates and heats the sample parallel to and apart from the lower surface of the table and fixedly to the table. 2nd I to do! A belt-like heating source is provided, and the second radiant heating source is moved by the moving means relative to the first longitudinal radiant heating source in a direction substantially perpendicular to the longitudinal direction of the first longitudinal radiant heating source, thereby melting the belt-shaped radiant heating source. The region is moved on the insulating layer, and when the belt-shaped melting region is moved, the humidity in the front region following the belt-shaped melting region is increased, and the belt-shaped melting Ft1 is increased.
How to pickle in one area f! Since the heating of the second radiant heating source is controlled by the heating control means so as to lower the temperature in zone 4, a zone where a large-area and high-quality single crystal semiconductor layer can be formed on insulator 1. A molten single crystal semiconductor layer forming apparatus can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a zone melting type single crystal semiconductor layer forming apparatus according to an embodiment of the present invention. FIGS. 2A and 2B are diagrams for explaining control of the temperature distribution in the scanning direction of a sample wafer in an apparatus for forming a conductor layer on a band-melting single crystal according to an embodiment of the present invention. Fig. 3 is a diagram showing a zone melting type single crystal semiconductor layer forming apparatus using a conventional carbon heater. Fig. 4 is a cross-sectional view of a sample wafer. Fig. 5 is a diagram showing a conventional tubular lamp. 6 is a diagram showing the zone melting type single crystal semiconductor layer forming apparatus used. FIG. 6(A) is a cross-sectional view of the sample during zone melting, and FIG. ) is a plan view including a polycrystalline silicon layer. In the figure, 3 and 30 are sample wafers, 6 is a single crystal silicon substrate, 7.9 is a silicon dioxide layer, 8 is a polycrystalline silicon layer, 10 is a silicon nitride layer, 12 is a tubular lamp for forming a melt, and 120 is a a reflecting mirror; 14 is a wafer holding plate;
19a to 19j are tubular lamps for heating the substrate, 20 is a control device, and 21 is a position sensor. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 3 Figure 4

Claims (7)

[Claims] (1) In a sample including an insulating layer and a single crystal or amorphous semiconductor layer formed on the insulating layer, the semiconductor layer is melted in a band shape, and this band-shaped melted region is moved on the insulating layer to An apparatus for single-crystallizing a semiconductor layer, comprising: a table on which the sample is placed; and a table provided on the side of the sample placed on the table with respect to the table, parallel to the top surface of the sample and separated from the top surface of the sample; a first longitudinal radiant heating source that irradiates and heats the semiconductor layer to melt the semiconductor layer in a band shape; on the opposite side of the table from the first longitudinal radiant heating source;
a second radiant heating source that is fixedly provided parallel to and apart from the lower surface of the table and irradiates and heats the sample; a moving means for moving relative to the first longitudinal radiant heating source in a direction substantially perpendicular to the longitudinal direction of the source; A zone melting type single crystal semiconductor layer forming apparatus, comprising: heating control means for controlling heating of the second radiant heating source so as to increase the temperature and lower the temperature of a rear region following the belt-shaped melting region. (2) The zone melting single crystal semiconductor layer forming apparatus according to claim 1, wherein the polycrystalline or amorphous semiconductor layer is a silicon layer, and the insulating layer is a silicon dioxide layer. (3) The zone melting type single crystal semiconductor layer forming apparatus according to claim 1, wherein the first longitudinal radiant heating source is a tubular lamp. (4) The second radiant heating source is comprised of a plurality of tubular lamps, each tubular lamp being spaced apart from each other and having their tube axes substantially parallel to the longitudinal direction of the first elongated radiant heating source. A zone melting type single crystal semiconductor layer forming apparatus according to claim 1. (5) The second radiant heating source includes a plurality of linear heaters, each of which is spaced apart from each other, and whose longitudinal axis is substantially parallel to the longitudinal direction of the first elongated radiant heating source. A zone melting type single crystal semiconductor layer forming apparatus according to claim 1. (6) The second radiant heating source is comprised of a plurality of linear arc torches, each of which is spaced apart from each other, and whose longitudinal axes are substantially parallel to the longitudinal direction of the first longitudinal radiant heating source. A zone melting single crystal semiconductor layer forming apparatus according to claim 1. (7) The heating control means is inserted between the table and the second radiant heating source so as to be positioned corresponding to the rear region following the band-shaped melting region of the sample, and 2. The zone melting type single crystal semiconductor layer forming apparatus according to claim 1, which is a heat insulating material fixedly provided with respect to the heat source.