JPS60189264A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an SOI structural MIS semiconductor device using especially a seed by a method wherein a substrate is used as one of wirings by connecting the substrate to the source or the drain of a transistor to be held in the same electric potential therewith, or a single crystal of semiconductor is formed on the substrate exposing a part thereof, and moreover a single crystal thin film is formed using the single crystal thereof as a seed crystal. CONSTITUTION:A silicon oxide film 10 is formed on a silicon substrate 9 similarly as usual, a hole is opened at a part thereof, and the silicon substrate is exposed to form a seed region. Then, after the substrate is washed, a silicon film is grown on the whole surface, and moreover, the surface is polished to flatten the surface as to leave the silicon film on the silicon oxide film 10. Then the silicon is molten using annealing technique, recrystallized from the seed, and a silicon single crystal thin film 13 containing no impurity is formed. Then, the silicon single crystal thin film 13 is patterned to form a silicon island as to make the seed region to exist under the thin film thereof. After then, impurity ions are implanted with a high accelerating voltage as to dope only the seed region 11 without using a mas to the silicon single crystal of the seed region 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure and manufacturing method of a MIS type semiconductor device.

MIS type semiconductor devices formed on semiconductor thin films provided on insulators, so-called SOI (8 emi-conduct
MIS-type semiconductor devices with a (or on inverter) structure have smaller junction capacitance and wiring capacitance than conventional MIS-type semiconductor devices, and isolation between elements is simple and complete, making them suitable for large-scale integrated circuits (LSI). It is attracting attention as a semiconductor device.

FIG. 1 (al is a conventional MID) transistor, and FIG. 1 (b) is a schematic cross-sectional view of an 80I structure M-S transistor. Here, 1 corresponds to a semiconductor substrate, 2 an insulating film, 3 a gate electrode, 4 a wiring metal, 5 an interlayer insulating film, and 6 a semiconductor thin film. However, in an MIS transistor having an SOI structure, it is very difficult to form a semiconductor thin film of good crystallinity on an interlayer insulating film uniformly and in a large area, which is a big problem. One method for solving this problem is to grow the semiconductor thin film 6 using the semiconductor substrate 1 as a seed crystal.

FIG. 2 (aJ to (d)) are schematic cross-sections showing the main steps of a method for manufacturing an 80I structure using seeds.

First, an insulating film 5 is placed on a semiconductor substrate 1 as shown in FIG.
A seed region is formed by forming a hole in a part of the hole.

Next, as shown in Figure fb1, a polycrystalline or amorphous semiconductor thin film 7 is deposited on the entire surface by CVD or the like.

Next, as shown in Figure (C), this is melted using an annealing technique such as laser annealing or electron beam annealing and recrystallized from the seed to form a single crystal semiconductor thin film 6. Next, as shown in FIG. 3(d), a portion of the semiconductor thin film 6 which is to become the active layer of the semiconductor device is separated and completed.

However, although the above method can improve the crystallinity of the semiconductor thin film, it is necessary to newly provide a seed region, which causes a significant reduction in the degree of integration.

Furthermore, since it is necessary to protect the seed region from introducing unnecessary impurities in subsequent steps, there is a problem that the number of steps increases, and this method is not sufficient in practice.

Furthermore, with the shift to LSI integrated circuits, optimizing the layout of interconnections is one of the important issues as well as optimizing the structure of semiconductor devices. In general, wiring layout is constrained by the following basic rules. (1) Wiring for different purposes (for example, input signal lines and output signal lines) must not touch. (2)
The number of wiring layers, the width of wiring, and the spacing between wiring have lower limits determined by the manufacturing process. (3) The wiring area is restricted by the shape, number, and position of the through holes. Therefore, the wiring layout has to be optimized in accordance with the above rules, making it a very difficult task. recent years.

2 or 3 layers to cope with the complexity of wiring due to LSI
Multilayer wiring is becoming common. However, even if multilayer wiring is used, the wiring area is limited by through holes.
As I became larger, it became more and more difficult, and the technology was not sufficient. This problem is solved by the MIS I of the SOI structure.
- The same applies to semiconductor devices including transistors,
It had become an important issue.

SUMMARY OF THE INVENTION An object of the present invention is to provide a MIS type semiconductor device which eliminates the above-mentioned drawbacks, particularly an 80I structure MIS type semiconductor device using a seed, and a practical manufacturing method thereof.

According to the present invention, in a semiconductor device including an MI8 transistor formed in a semiconductor thin film provided on a low-resistance semiconductor substrate via an insulating film, the source or drain of this transistor and the semiconductor substrate are connected to have the same potential. By holding the semiconductor substrate, a semiconductor device characterized in that the semiconductor substrate is used as one of the wirings of the semiconductor device is obtained.

Furthermore, an insulating film is formed on the impurity semiconductor substrate so that a portion thereof is exposed, and then the semiconductor atoms are epitaxially grown on the entire surface at a low temperature such that impurities in the semiconductor substrate hardly diffuse. It is characterized by forming a semiconductor single crystal containing almost no impurities on the partially exposed semiconductor substrate, and using this as a seed crystal to form a semiconductor single crystal thin film containing almost no impurities on the insulating film. A method for manufacturing a semiconductor device is obtained.

FIG. 3 shows a schematic cross-sectional view of an MIS type semiconductor device having an 80I structure according to the present invention. Here, 2.3°4.5.6 is equivalent to that in FIG. 1, and 8 is a low resistance impurity semiconductor substrate. The features of the present invention (1) can be summarized in the following two points. One is that the seed region is provided under the semiconductor device (semiconductor thin film 6 in the figure), and the other is that the semiconductor substrate 8 is actively used as wiring for the semiconductor device. In the former case, the seed region is covered with the semiconductor thin film 8, so the degree of integration is the same as that of an 80I structure MIS semiconductor device that does not use a seed, and the number of steps is reduced because there is no need to protect the seed region. Moreover, since the seed is close to the active layer of the semiconductor device, there is an advantage that an active layer with better crystallinity can be formed. On the other hand, in the latter case, the semiconductor substrate 8 can be used as a source or drain wiring of the semiconductor device, specifically, as a power supply line, so there is no need for source or drain wiring on the surface of the semiconductor device. Therefore, in the layout of the wiring on the surface, one wiring and the corresponding through hole are reduced, which greatly increases the degree of freedom in wiring, which greatly simplifies the design and has the advantage of being highly integrated. As described above, according to the present invention, a MIS type semiconductor device having a highly integrated SOI structure with good crystallinity and a large degree of freedom in wiring can be obtained.

Next, the manufacturing method will be described. If the structure of the invention is to be realized, the method developed for obtaining the conventional structure (FIG. 2) is not suitable.

This is because, in order to realize this structure using conventional processes, a semiconductor substrate with low resistance or high concentration of impurities is used as a seed, and as shown in Figure 2(b), a polycrystalline layer is formed on the surface of the semiconductor substrate. A semiconductor thin film is deposited, and then it must be melted and recrystallized from a seed using an annealing technique such as laser annealing or electron beam annealing, as shown in (C).

However, the semiconductor thin film that becomes the active layer of the semiconductor device must be an intrinsic semiconductor due to the design of the semiconductor device, whereas the seed is a highly concentrated impurity semiconductor substrate.
This is because the melting point of the semiconductor substrate, which is a seed, is lower than the melting point of the semiconductor thin film, and recrystallization begins not from the seed but rather from the semiconductor thin film, and there is also the problem that impurities from the semiconductor substrate diffuse into the semiconductor thin film. It is.

The manufacturing method of the present invention, which has been devised in order to realize the structure of the present invention, will be described in detail below based on an example of an 80I structure NMO8 or PMO8 transistor using a silicon substrate. Part 4, fa) to (d), are schematic cross-sectional views showing the main steps of the manufacturing method according to the present invention. Here, 9 is a low-resistance single crystal silicon substrate containing impurities at a high concentration, 10 is a silicon oxide film, 11 is a silicon single crystal in a seed region, 12 is a silicon polycrystalline thin film,
13 corresponds to a silicon single crystal thin film. In addition, when forming a "::8 MO8 transistor on the upper part of the silicon substrate 9, for example, an N-type silicon substrate with As 111Jr-punto (impurity concentration bone 1 0-3.ρ 1 0-30) is used.
・α) When forming a PMOS transistor on the upper part, a P-type silicon substrate doped with boron, for example (impurity concentration tt1.l'lI3.

A silicon oxide film 10 with a thickness of 1.0 μm was formed on the film by CVD, and a hole was made in the film to expose the silicon substrate.
A silicon film with a thickness of 7 nm is grown over the entire surface, and the surface is further polished 2 (mechanochemical polishing) to flatten it so that a 0.5 μm silicon film remains on the silicon oxide film 10.The substrate temperature is as low as 600°C. Therefore, the seed region contains silicon single crystal 1 containing almost no impurity 4M.
1 is formed and silicon, -1 is melted using an annealing technique such as laser annealing or electron beam annealing as shown in FIG. Forms silicon islands.

After that, the silicon single crystal of the seed region 11 is doped with an impurity (for example, phosphorus at a dose of lX1016c when the substrate is N type).
IrL', when the substrate is P-type, the present invention is manufactured by implanting, for example, boron at a dose of I x 10"cm-2) without a mask at a high acceleration voltage so that only the seed region 11 is doped. An example process is completed.

According to the manufacturing method of the present invention illustrated here, an intrinsic semiconductor thin film can be formed regardless of whether the semiconductor substrate serving as a seed is N type or P type, and the alignment process is the same as in the conventional method. This is revolutionary in that the structure according to the present invention can be realized relatively easily.

Above is the SO1 structure using silicon substrate! Although the method for manufacturing NMO8 and PMOS transistors has been explained as an example, it is clear that the method can be implemented using other semiconductor substrates (such as gallium), and also for circuits with 0MO8 configuration, the wiring of either the NMO8 or PMO81-transistor can be connected to the substrate. The present invention is effective because it is only necessary to connect the

[Brief explanation of drawings]

In FIG. 1, fat is a schematic cross-sectional view of a conventional MIS type semiconductor device, (bl is a schematic cross-sectional view of a conventional MIS type semiconductor device with SOI structure. Figures 2 (a), (b),
tc+. (dl is a diagram illustrating a conventional SOI structure manufacturing method and sequentially shows substrate cross sections in main steps. 1. FIG. 3 is a schematic sectional view of an MIS type semiconductor device with an SOI structure according to the present invention. Figure 4 1al, tbl
, (C). (d) is a diagram illustrating a method for manufacturing an SOI structure according to the present invention, and is a diagram sequentially showing cross sections of a substrate in main steps ζ. In the figure, 1 is the semiconductor substrate, 2 is the insulating film, 3 is the gate electrode,
4 is a wiring metal, 5 is an insulating film between eyebrows, 6 is a semiconductor thin film, 7 is a semiconductor polycrystalline thin film, 8 is a low resistance impurity semiconductor substrate, 9
is a low-resistance silicon substrate, 10 is a silicon oxide film, and 11 is a silicon oxide film.
12 is a silicon single crystal thin film in the seed region, 12 is a silicon polycrystalline thin film, and 13 is a silicon single crystal thin film.乎 1. 2 Figures (a) (b) (c) (d)

Claims (2)

[Claims] (1) In a semiconductor device including a MIS1 transistor formed in a semiconductor thin film provided on a low-resistance semiconductor substrate via an insulating film, the source or drain of this transistor and the semiconductor substrate are connected and kept at the same potential. A semiconductor device characterized in that the semiconductor substrate is used as one of the wirings of the semiconductor device. (2) Forming an insulating film on the impurity semiconductor substrate so that a portion of the impurity is exposed, and then epitaxially growing the semiconductor atoms on the entire surface at a low temperature such that the impurities in the semiconductor substrate hardly diffuse. A semiconductor single crystal containing almost no impurities is formed on the partially exposed semiconductor substrate, and this is used as a seed crystal to form a semiconductor single crystal thin film containing almost no impurities on the insulating film. A method for manufacturing a semiconductor device.