JPS58180019A - Semiconductor base body and its manufacture - Google Patents

Abstract

PURPOSE:To form a semiconductor element such as a high-speed type bipolar element by applying a single crystal change method for a semiconductor polycrystalline film or an amorphous film, at least one part thereof is positioned onto an insulating film and other one part thereof is in contact directly with a semiconductor substrate. CONSTITUTION:Line and space by insulating films 22 and opening sections 28 as seed crystals are formed to the substrate 21 through LOCOS oxidation by a normal method by using a rectangular mask A. The amorphous layer or the polycrystalline layer changed into a single crystal is loaded onto the whole surface on the line and space. Sections corresponding to the opening sections 25 of insulating sections are left while using a mask B through which rectangular windows are left by a # type pattern, and the insulating sections 23, 24 are formed through processes of nitriding, etc. through which the insulating sections are not oxidized into polycrystalline layers. The surface can be flattened approximately by previously etching the sections and reducing thickness to approximately half at that time. Substrate extending sections 27 as amorphous or polycrystals are changed into single crystals through the irradiation of energy beams. Either of a pulse laser, a CW laser, electron beams, infrared rays, ultraviolet rays, etc. may be used as beams irradiated, and they may be used when energy is absorbed and dissolved to the substrate extending sections 27 in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor body equipped with a type of isolation region and a method of manufacturing the same.

The insulation isolation method has traditionally been a very important technology for semiconductor devices, and is positioned as a technology that will become even more important in the future, especially in bipolar devices and the like, as speeds and densities become higher. Conventionally, as shown in FIG. 1(a), an insulating separation layer 12 is formed in a semiconductor substrate 11 from the surface, and the remaining region in between is used as an active layer 13 to incorporate an element. At this time, when the distance between the separation layers 12 is shortened in order to increase the density, large stress begins to act between them, causing crystal defects and deteriorating device characteristics.
), there were limitations such as the formation of bird's beaks 14 and the inability to reduce the distance between the separation layers 12. On the other hand, as shown in FIG. 1(b), the insulating separation layer 1
Attempts have been made to form 2 inside 11. For example, the structure shown in Figure 1(b) is formed by deeply implanting oxygen by ion implantation to form an oxide, but this method has the drawback that implantation defects remain and a large amount of oxygen must be implanted. The drawback is that it is not very realistic.

Other attempts have also been made to achieve complete insulation separation using anodic acid I1, but there are various problems and the technology is still incomplete.

The present invention aims to provide a new method for forming such an insulating separation layer, and to realize a high-speed type IBORA device using the method.

In the method of the present invention, a single crystallization method is applied to a semiconductor polycrystalline film or an amorphous film in which at least a part is on an insulating film and the other part is in direct contact with a semiconductor substrate.

Various proposals have been made regarding this single crystallization method over the past few years. The proposed technology will be briefly explained below.

There is a technology that converts a polycrystalline film left on an insulating substrate (for example, 5102 or 5isNa) by etching into a single crystal or into large crystal grains using a so-called beam annealing method such as CW, pH1se laser annealing, or electron beam annealing. . Although this method yields fairly good single-crystal islands, it is impossible to control the crystal orientation, and since seed crystals are generated miscellaneously from around the islands, large-sized complex islands consisting of large crystal grains are likely to occur. Shortcomings are acknowledged.

However, the graph-o-epitaxy method attempts to form a single crystal thin film on an amorphous insulating film using a beam annealing method.
This method is the same as the above method, but attempts to control the crystal orientation, which was not possible with the above methods, by preparing in advance very fine grooves corresponding to the crystal habit on the amorphous substrate. It is. However, currently KGl
Although some success seems to have been achieved in growing single crystals from aqueous solutions, satisfactory results have not been achieved with semiconductor films such as Si. In other words, this method does not have a size large enough to form semiconductor devices (a few μm square), and it is currently not possible to analyze device characteristics, crystal defects, small-angle grain boundaries, twin crystals, etc. This is not a usable technology.

In bridging epitaxy and sheepoid beam annealing, the crystal orientation is controlled to some extent because the substrate is used as a seed crystal.

However, as is well known, crystal defects start to occur at the point where the crystal grows from the seed crystal part to the insulating layer.
After 3 μm growth, phenomena such as polycrystalization occur. Especially in sheepoid beam annealing,
As a single crystal grows from the opening to the periphery, the part where the crystal orientation of the substrate continues accurately and grows does not extend to 1 μm around the periphery, and grows as a polycrystal with a large grain size (1 to 6 μm), so it looks like a chrysanthemum. observed. It is thought that such a symmetrical shape corresponds to a concentric temperature distribution with the opening serving as a heat sink.

On the other hand, in bridging epitaxy, single crystals are grown from both sides using seed crystals on both sides as bridge piers. The seed crystal part and the insulating part on which the polycrystalline material is placed alternately form lines and spaces in parallel, and a total of about 3 μm from both sides is almost monocrystalline. However, grain boundaries such as small-angle grain boundaries and large defects remain in the central portion where both sides collide. Furthermore, it has the disadvantage that bridging wider than that is difficult. The reason why a somewhat larger single crystal can be obtained with bridging epitaxy is probably because the symmetry of the heat distribution is closer to uniaxiality than with sheepied beam annealing. This means that single crystallization by CW laser annealing, which has a slow cooling rate and strong temperature distribution anisotropy due to heat conduction, is better than single crystallization by pulsed laser annealing, which has very little temperature distribution anisotropy. This can be seen from the fact that better results were obtained than in crystallization. That is, it can be seen that when the cooling rate is slow, heat flows to the seed crystal portions that are linearly arranged heat sinks, making it easier to realize a periaxial temperature distribution. However, since the beam diameter of a laser or the like is small, this more uniaxiality naturally breaks down in the peripheral area of the beam, which is thought to be the cause of poor crystallinity. This means that the growth area of a single crystal with good crystallinity and orientation is almost limited to the central part of the laser beam, and even if the overlap of the scanning laser beams is increased, the crystallinity cannot be improved. This is probably due to the fact that it is rarely done.

The present invention improves the uniaxiality of temperature distribution as discussed above, realizes a structure suitable for single crystal growth that takes into account crystal growth habits, and overcomes various drawbacks of conventional methods. The present invention provides an isolated type single crystal substrate having improved crystallinity, and at the same time provides excellent semiconductor devices such as high-speed bipolar devices and MO8 devices.

The present invention provides electrical insulation and thermal insulation (low thermal conductivity).
The shape and arrangement of both the so-called relief, which serves as a heat sink, and the opening, which is both a heat sink and a seed crystal, produces a uniform heat flow that is as close to axial as possible, and at the same time produces crystal growth. In addition, it is a unique method that has the effect of improving the crystallinity of areas where defects are likely to occur due to the auxiliary crystal orientation control effect of the relief of the opening with sharp edges, and it is also effective for insulation separation heat flow control and relief complementation. This can be called a type epitaxy method.

The present invention will be explained below using a basic embodiment shown in FIG. (a) shows a cross section taken along line I-1' in the plan view (b). The stretch in FIG. 2(b) is the portion excluding the laminated portion. A first insulating film 22 is formed in the shape of parallel strips on a substrate 21, and second insulating films 23 and 24 are formed above and orthogonally to form a window 25 consisting of a rectangular insulating part. There is. A rectangular opening 26 is formed by the second insulating film 23 and the first insulating film 22. Normally, no matter how sophisticated an etching method is used, or when an insulating film is formed at once by nitriding or oxidizing a protective film, the corner portion of the opening 26 will be rounded. Second
In the structure shown in the figure, the insulating film 2 is printed twice in a rectangular shape on a straight line.
2 and 23.24, the corner portion of the opening 26 is formed very sharply.

As mentioned above, this exhibits a useful effect as a so-called relief, which accurately maintains the orientation of the crystal grown from the seed crystal.

In this embodiment, the two sides of the opening 26 made of the insulating films 22 and 23 are not only parallel to the insulating film 23 (part of the rectangular insulating section 26), but also completely coincident with each other.

Inside the window 25 of the rectangular insulating section, in contact with the opening 26, a single crystallized region, that is, a substrate extension section 27 is formed so as to partially protrude above the first insulating film 22. The substrate extension portion 27 and the substrate 26 are used as a region for fabricating currently manufactured semiconductor devices, that is, a device substrate. The opening 26 in FIG. 2 has the feature of serving not only as a seed crystal but also as a conductive path connecting the substrate 26 and the substrate extension 27.

Furthermore, it goes without saying that the substrate extension portion 27 can be regarded as the substrate 21, an opening can be formed in this portion, and the same type of structure can be further laminated.

In the example shown in FIG. 2, the opening is 2°6. The windows 25 of the insulating portion are all rectangular, but the same effect can be obtained by configuring them in a rhombus shape in accordance with the orientation of the substrate and the orientation of crystal growth as will be described later.

Further, although a part of the periphery of the opening 26 and the window 25 of the insulating part is common, it does not necessarily have to be the same, and it is sufficient that they are approximately parallel to each other even if there is a slight gap. .

Next, the production of an insulated single crystal substrate having the structure shown in FIG. 2 will be explained.

First, LOGO 8 is oxidized on the substrate 21 using a rectangular mask using a conventional method to form lines and spaces between the insulating film 22 and the opening 28 which will serve as a seed crystal as shown in FIG. The thickness of the insulating film 22 may be 0.3 to 1.0 μm, which is commonly used.

On top of this, an amorphous layer or a polycrystalline layer (thickness 0.2 to 1.0 mm) to be converted into a single crystal is stacked on the entire surface.

Next, using a mask B that leaves a rectangular window with a N-shaped pattern, the polycrystalline layer is subjected to a process such as oxidation or nitriding, leaving a portion corresponding to the opening portion 26 of the insulating portion. Form 24.

At this time, the surface can be made almost flat by etching this portion in advance to reduce the thickness to a certain extent.

Also, before or after this step, the state of the interface between the opening 26, which will serve as a seed crystal, and the substrate extension 27 is improved by ion implantation or the like. Crystal growth is improved when the interface is dirty.

Furthermore, as is clear from the above steps, the opening F6 is formed by the end face of the insulating film 22 and the end face of the window 25 of the insulating part, so even if one side of the opening 26 is 0.5 μm, for example,
The corners are not rounded and a rectangular shape is formed well. Current standard photolithography does not allow for the creation of such small openings, which are usually rounded. It is believed that the rectangular opening with such precise corners exhibits an effective relief effect as recognized in grapho-epitaxy, and contributes to the good crystallinity according to the present invention.

Next, an energy beam is irradiated to convert the amorphous or polycrystalline substrate extension 27 into a single crystal.

The irradiation beam is a pulse laser or a CW laser.

Any electron beam, infrared rays, ultraviolet rays, etc. may be used, and the energy is absorbed by the substrate extension part 27 in a short time.
As long as it can be dissolved. According to studies by the present inventors, the required irradiation energy varies depending on the quality and type of laminated films, and the temperature of one substrate, which varies depending on the state of the protective film covered thereon. However, in our study, C
Although there are problems such as instability of the W-MR laser annealing equipment and poor reproducibility of fine laminated structures,
At 0 to 600°C, the Daikoku energy to the substrate is 3 to 11.
W, scanning speeds ranged from 30''/sec to 3''/sea. At this time, during melting, the thickness was approximately 30 μm.

It was found that the time during which the rectangular substrate extension portion 27 was irradiated with this beam was about 0.01 to 1 m5eo, and that melting and crystal growth took place in this short time. Even in pulsed laser annealing and electron beam annealing,
If melted and crystals are grown during the time, the above-mentioned CW-
It is estimated that a single crystal having the same quality as a single crystal recrystallized by a MU laser can be obtained.

Furthermore, as a result of a simple experiment conducted by the present inventors, in order to obtain a good crystal with few crystal defects, the irradiation beam radius should be adjusted to the extent that the substrate extension portion 27 extending above the first insulating film 22 is stacked. It needed to be larger than the length of section 29. This means that the board extension portion 27 surrounded by the insulating portions 23 and 24
This can be understood by considering the heat distribution. That is, the center of the beam is at the boundary between the seed crystal 28 and the insulating layer 22, and even if it is a heat sink, sufficient energy is irradiated to melt a part of the boundary surface of the seed crystal, causing the inside of the seed crystal to melt. Crystal growth begins at , and then heat flows uniformly and uniaxially, ie perpendicular to the lines of the seed crystal 28, to the heat sink. Therefore, it is thought that crystal growth uniformly proceeds in the opposite direction to the heat flow.

If the beam diameter is sufficiently smaller than the window 25 of the insulator, melting occurs in the form of a spot and the heat flow is directed towards the center of the spot and the -axiality is lost. moreover,
In this case, the substrate extension part 27 within the same window 25 is scanned many times, and partial melting and crystal growth are repeated within the same window, resulting in minute differences in crystal orientation. ,
Furthermore, it is understandable that the experimental results show that heating and cooling increase the generation of distortion and defects.

Although the crystallinity of the substrate extension 27 thus obtained is good, considerable thermal stress remains.

It is also considered that thermal stress remains between the surrounding insulating film and the surrounding insulating film. To leave this, 700~10oo℃3
Annealing for about 0 minutes is very effective.

In FIG. 2, the opening 26 is located approximately at the center of the window 26 of the insulating portion, but it goes without saying that it may be located closer to either side. Also, the opening 26
Of course, it is also possible to completely oxidize the recrystallized portion immediately above to completely insulate and separate the substrate extension portion 27 into two.

Furthermore, it is clear from the above discussion that even if the recrystallized portion directly above the opening 26 is used as a channel and the substrate extensions 27 extending on both sides are used as the source and drain, a great effect of insulation isolation can be obtained.

Another embodiment is shown in FIG. On the semiconductor substrate 31, the first
The insulating film 32 is formed by, for example, the LPCVD method. A polycrystalline layer is further placed on the entire surface of the insulating film 32 formed in a strip shape in the same manner as described above, and an insulating portion 33 is formed to surround the opening portion 36 of the insulating portion in the same manner as described above. The subsequent steps are the same as the method described above. A feature of this example is that it is relatively easy to form elements in advance under the insulating film 32, so that the area of the semiconductor substrate can be used effectively.

Next, regarding the orientation of the opening and the window of the insulating part, see Figures 4 and 6.
This will be explained using figures.

In the present invention, recrystallization occurs from a seed crystal, so orientation is controlled. However, as mentioned above, it has a great auxiliary effect as a relief. Therefore, it is natural that something with a symmetry similar to that of the seed crystal has excellent crystallinity. In FIGS. 4 and 6, an SS crystal having cubic crystals will be explained as an example.

For the sake of simplicity, for example, the (100) plane is 10o.
, 010,001. In addition, the (110) direction in the figure is referred to as (110) in the following explanation.
110) is perpendicular to the plane.

According to the studies of the present inventors, as shown in two examples in FIG. 4 (IL), when a substrate with a 100 plane as the main plane is used, the rectangular opening in FIG. The best crystallinity is when the periphery of the window 25 of the portion 26 and the insulating portion is in the (110) direction or the <1oo> direction, that is, approximately perpendicular to the (110) plane or the (10o) plane. Obtained. This is particularly possible because the symmetry of the rectangular opening 26 serving as a relief matches the crystal orientation of the seed crystal.

As shown in FIG. 4(b), when using a substrate with a (110) plane as its main plane, the rectangular opening 26 in FIG.
and the periphery of the window 26 of the insulating part is the (100) plane and (1
Particularly good crystallinity was obtained when the crystallinity was approximately perpendicular or parallel to the 1Q) plane.

FIG. 5 shows the second side with particularly excellent crystallinity when a substrate with a (111) plane as its main plane is used.

As shown in the figure, in either case, the periphery of the opening 26 in FIG. 2 is approximately perpendicular or parallel to either the (110) or (211) plane. Among these, the shape with particularly excellent crystallinity is shown in FIG.
0) and (211) were parallel to each other, forming a rectangle.

The objects shown in Figures 5 and 5C are (110) planes or (
211) It consists of a periphery that is parallel to only one side of the plane, and as you can see from the figure, it has a rhombic shape.

The end of the first insulating layer 22 and the second insulating layer 23 in FIG.
The ends of the two do not meet at a right angle, but at an angle of 6o.

Therefore, considering the heat flow, the symmetry is slightly broken and there is little uniformity, so it seems that the crystallinity is not very good, but the effect of the relief is large and as a result, the crystallinity is good. It is thought that it became a sexual thing. As shown in the above embodiment, the first and second insulating layers are formed in two parts, so this 60 degree angle is formed sharply, which is also the reason why the relief effect is large. It seems that there are. At this time, if the first and second insulating layers are formed at the same time, the edges will naturally become rounded and the relief effect will be lost.

The reason why much better crystals are obtained in the present invention than in the conventional bridging epitaxy and sheepied beam annealing is due to the effect of such relief and the crystal growth by the heat flow control introduced by the present invention. It is clear that this is due to control. Moreover, it is an excellent product in which the crystal orientation is accurately controlled.

The following are non-limiting examples of the invention.

<Example 1> Using a mask, the width of the first oxide layer (FIG. 2 22) is 1
Two 5 μm seed crystals formed alternately arranged lines and spaces with a width of 1.5 μm (FIG. 2, 28). On top of this, polycrystalline silicon is deposited to a thickness of approximately 0.5 μm using the LPCVD method.
Thick laminate top. At this time, the substrate temperature was maintained at 500°C. Next, a window with a width of 4 μm and a length of 10 μm, and a window with a width of 4 μm and a length of 14 μm.
Using a mask B having three different types of windows: a window with a width of 4 μm and a window with a width of 4 μm and a length of 18 μm, the polycrystalline portion surrounding the substrate extension 27 is oxidized as shown in FIG. (+L)
A completely oxidized layer was obtained by arranging the structure as shown in the figure. The sizes of the obtained windows are approximately 3 x 9 μm and 3 x 13 μm, respectively.
, 3×17 μm. At this time, the lengths of the first insulating film stacking part (FIG. 2 29) are approximately 3 μm and 5 μm, respectively.
, 7 μm.

CW-mura laser irradiation was continued. The substrate temperature) is approximately 350°C, the scanning speed is 30”/sec+, the laser energy is approximately 5W, and the polycrystalline S1 melted at this time.
The width was a little over 25 μm.

The resulting single-crystal layer was lightly etched with Seco etchant and examined using a dark-field optical microscope. It was found that single crystallization using the above three types of windows was successfully carried out. However, a window with a loading part that is more than 10 times as thick as 05 μm, 3
Regarding 7 μm, it was partially observed that small crystals on the other side were formed at about 2 μm from the edge. In other parts, almost no crystal defects were observed, indicating that the crystal was excellent.

Note that the microcrystalline portion formed at the end is a very small portion, and if this portion is used, for example, as a source, drain, or contact, it is possible to avoid adverse effects due to disordered crystal orientation.

Therefore, it has been found that if the crystals are used in this way, the crystals will no longer be of poor quality and cannot be used.

<Example 2> Through the same steps as in Example 1, a laminated single crystal laminated plate having a similar structure was created. However, at this time, as a result of rotating the mask B by 15 degrees compared to Example 1, the opening is not rectangular but diamond-shaped. The crystallinity of the obtained substrate extension is
The 3 x 9 μm window was good, but the other two large windows were unsatisfactory, and a considerable number of defects and polycrystals were observed from a position 3 to 4 μl from the edge of the seed crystal. .

<Example 3> The same treatment as in Example 1 was performed. However, in this example,
CW-mura laser irradiation at approximately 10W, scanning speed 3000
''/sec. The melting width of the polycrystalline silicon at this time was about 30 μm. The crystallinity of the obtained single crystal was almost the same as the result of Example 1.

<Example 4> The same treatment as in Example 2 was performed. However, the CW-muralaser irradiation was about 4 W and the scanning speed was 3000"Vg 6 C. The melting width of the polycrystalline silicon at this time was about 20 μm. The crystallinity of the obtained single crystal was There were also many defects and many grain boundaries were observed.

<Example 6> Using a substrate having a (111) plane as its main plane, Example 1
I did the same process. The arrangement of the windows is in the orientation shown in Figure 5a. The crystallinity of the obtained single crystals was that of Example 1.
It was equally excellent.

<Example 6> The same study as in Example 6 was conducted. However, in this embodiment, the windows were arranged in the directions shown in FIGS. 6 and 6C. The crystallinity of the obtained single crystals was all quite good, but was somewhat inferior to that of Example 6. However, it was better than that of Example 2.

<Example 7> An experiment similar to Example 1 was conducted. However, in this study, polycrystalline silicon was subjected to plasma CVD electron beam annealing at a thickness of approximately 0.3 μm. The warping irradiation conditions are: acceleration energy ts Kev, current 3mm, substrate dust soo℃
, the scanning speed was 20oO1nVseC.

At this time, the thickness of the silicon layer during melting was about 50 μm. The crystallinity of the obtained single crystal layer was almost the same as that obtained in Example 1, and it was found that almost the same results could be obtained with a laser beam or an electron beam.

[Brief explanation of the drawing]

FIG. 3 is a cross-sectional view of another semiconductor substrate according to the present invention, and FIGS. 4(IL), (b), and 6 are views schematically showing the orientations of the opening and the window of the insulating portion. 21.31...Substrate, 22 y 23 y
24 p 33... Insulating film, 26...
...Insulating section window, 26...Opening, 27, 37
・・・・・・Extended part of the board. Name of agent Patent attorney Toshio Nakao and 1 other person A0 Figure 1 (α, (b> Figure 3 Figure 5)

Claims (1)

[Scope of Claims] (1) A rectangular or diamond-shaped opening formed in an insulating film on a substrate, a monocrystalline substrate extension that contacts the substrate through the opening, and a rectangular or diamond-shaped opening that contacts the substrate through the opening. 1. A semiconductor substrate having a rectangular insulating window separated from its surroundings in shape, and either the periphery of the opening or the periphery of the insulating window being substantially parallel to each other. G2) The semiconductor substrate according to claim 1, wherein the height of the tip of the substrate extension portion and the rectangular or rhombic insulating portion is approximately equal. (3) forming an insulating film having a rectangular or rhombic opening on the substrate; forming an amorphous or polycrystalline semiconductor film in contact with the substrate through the opening; a step of insulating the surrounding semiconductor film so as to partially leave the semiconductor film so as to form a rectangular or rhombic window having a peripheral portion that is substantially parallel to either side; 1. A method for manufacturing a semiconductor substrate, comprising the step of beam annealing. (4) Claim 3, characterized in that the thickness of the semiconductor film to be insulated is reduced before the insulating step.
A method for manufacturing a semiconductor substrate according to section 1. (6) The semiconductor according to claim 3, wherein in the step of performing beam annealing, the radius of the beam is larger than the extended portion of the substrate that protrudes above the insulating film formed on the substrate. Substrate manufacturing method. (6) In the step of performing beam annealing, a scanning beam annealing method is used, and the scanning direction is made substantially parallel to or perpendicular to the window of the rectangular insulating section. A method for manufacturing a semiconductor substrate according to section 1. (8) The method for manufacturing a semiconductor substrate according to claim 3, characterized in that in the beam annealing step, the beam residence time is 0.01 to 1 mSθC. (8) The main plane of the substrate is ( 100) or (110) plane, and the rectangular or diamond-shaped opening and the periphery of the insulating part are substantially parallel to or perpendicular to the (100) or (110) plane. The method for manufacturing a semiconductor substrate according to claim 3. (9) The main plane of the substrate substantially coincides with the (111) plane, and either the rectangular or rhombic opening or the periphery of the insulating part is ( The method for manufacturing a semiconductor substrate according to claim 3, wherein the semiconductor substrate is parallel to either the (110) or (211) plane.