JPH04332120A - Manufacture of semiconductor crystal layer - Google Patents

Abstract

PURPOSE:To easily form a semiconductor crystalline layer of high quality without mixing high melting point metal, etc., by irradiating it with an energy beam. CONSTITUTION:A semiconductor layer 3 to be annealed is formed on a substrate 1, an intermediate layer 4 is formed on the layer 3, and a high melting point metal film 5 is formed on the layer 4. In such a state, an energy beam (e.g. an electron beam) BM irradiates to anneal the layer 3 to be crystallized. A material such as metal, semiconductor compound, etc., for preventing formation of the semiconductor compound between the semiconductor material used for the layer 3 and the high melting point metal used for the layer 5 at the time of annealing, is used for the layer 4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor crystal layer in which a semiconductor layer on a substrate is annealed with an energy beam to crystallize the semiconductor layer as a semiconductor crystal layer.

0002

[Prior Art] In order to realize a stacked semiconductor device (three-dimensional IC), which is considered to be one of the highly integrated and high-speed semiconductor devices, a semiconductor thin film is formed on an insulating film. There is a method of converting this into a polycrystalline semiconductor layer or a single crystal semiconductor layer, that is, a semiconductor crystal layer with an increased crystal grain size, by irradiation annealing with an energy beam, and then forming an element on this layer.

By the way, when annealing a semiconductor thin film, for example, a silicon thin film, it is better to use an electron beam as an energy beam, which has better controllability and higher output than a laser beam. When annealing with an electron beam, damage caused by irradiation becomes a problem.

In order to prevent damage to semiconductor thin films caused by electron beams, a technique as disclosed in Japanese Patent Application Laid-Open No. 60-54426 is known. FIG. 4 is a diagram for explaining the method of manufacturing a semiconductor crystal layer disclosed in the above-mentioned publication. In this manufacturing method, a SiO2 layer 52 is first formed on a single crystal silicon substrate 51. After that, Si
A semiconductor thin film to be annealed, for example a silicon thin film 53, is deposited on the O2 layer 52, and a refractory metal film 54 of tungsten, molybdenum, tantalum, niobium, titanium or vanadium is formed thereon.

After the refractory metal film 54 is formed on the semiconductor thin film 53 in this manner, the electron beam BM is irradiated and scanned. Thereby, the semiconductor thin film 53 is heated and annealed to make it coarse grained or single crystallized. At this time,
Since the electron beam energy is well absorbed by the high melting point metal film 54 on the semiconductor thin film 53, damage to the semiconductor thin film 53 caused by the electron beam can be reduced to a level that does not pose a practical problem. Due to its good thermal conductivity, heat can quickly spread over the entire surface during annealing to obtain a uniform in-plane temperature distribution, which can improve the uniformity of annealing and easily create a high-quality semiconductor crystal layer. be able to.

[0006]

However, in the above-described method, when a silicon thin film is used as the semiconductor thin film 53, during annealing, there is a Even if a silicon compound (silicide) is formed and the high melting point metal film 54 and the silicide at the interface are removed during subsequent device formation, the high melting point metal remains in the crystallized silicon thin film 53, that is, the semiconductor crystal layer, and the device This has the disadvantage that it has an adverse effect on the characteristics of the device, such as the threshold value becoming unstable.

[0007] An object of the present invention is to provide a method for manufacturing a semiconductor crystal layer that can easily produce a high-quality semiconductor crystal layer by irradiation with an energy beam without mixing high-melting point metals, etc. .

[0008]

[Means for Solving the Problems] The present invention forms a high melting point metal film on the semiconductor layer when the semiconductor layer on the substrate is heated and annealed by irradiation with an energy beam. It is characterized in that it is not formed directly on the layer, but is formed via an intermediate layer to prevent the formation of a semiconductor compound. That is, as shown in Figure 1,
After forming a semiconductor layer 3 to be annealed on a substrate 1 (conceptually on which a SiO2 layer 2 may be provided) and forming an intermediate layer 4 on this semiconductor layer 3, the intermediate layer 4 is formed.
A high melting point metal film 5 is formed thereon. In this state, the semiconductor layer 3 is annealed and crystallized by irradiating it with an energy beam (for example, an electron beam) BM.

A semiconductor material such as silicon is used for the semiconductor layer 3, and a high melting point metal such as tungsten or molybdenum is used for the high melting point metal film 5.

[0010] Also, during annealing, the intermediate layer 4 contains the semiconductor material used for the semiconductor layer 3 and the high melting point metal film 5.
Materials such as metals and semiconductor compounds that prevent the formation of these semiconductor compounds with the high melting point metal used in the process are used. Specifically, such materials include:
Materials with relatively low diffusion coefficients in semiconductor materials or high melting points are preferred.

Table 1 shows the diffusion coefficients of various metals in silicon, and Table 2 shows examples of compounds with high melting points.

0012

[Table 1]

[0013]

[Table 2]

As can be seen from Table 1, when the semiconductor layer 3 is made of silicon, metals such as Co, Zn, and Ti are available as materials with relatively small diffusion coefficients in the semiconductor layer 3. When using metal, the intermediate layer 4 can be formed by EB evaporation. Furthermore, as can be seen from Table 2, materials with high melting points include SiO2, S
Examples include silicon compounds such as i3N4 and nitrides such as TaN and TiN.

As shown in FIG. 1, when the above-mentioned intermediate layer 4 is interposed between the semiconductor layer 3 and the high melting point metal film 5, for example, an electron beam is irradiated as the energy beam BM. Similarly to the conventional method, the semiconductor layer 3 can be heated and annealed to crystallize it with good quality. That is, in this case as well, about half of the electron beam energy is absorbed by the high melting point metal film 5, so damage to the semiconductor layer 3 caused by the electron beam can be reduced to a level that does not pose a practical problem. Due to the good thermal conductivity of the high melting point metal film 5, heat can be quickly diffused over the entire surface during annealing, thereby improving the uniformity of the annealing.

Furthermore, in the present invention, the semiconductor layer 3 and the high melting point metal film 5 are not in direct contact with each other, and the semiconductor material such as silicon forming the semiconductor layer 3 and the high melting point metal film 5 are placed between them. Since the intermediate layer 4 is provided to prevent the formation of a compound, for example, silicide, with a high melting point metal such as tungsten to be formed, it is possible to effectively prevent the high melting point metal from penetrating into the semiconductor layer 3 during annealing. can.

After the semiconductor layer 3 is annealed and crystallized in this manner, the high melting point metal film 5 and the intermediate layer 4 are removed, and an element can be formed on the semiconductor layer 3. In this case, the semiconductor layer 3 is well crystallized (polycrystalized or single crystallized), and the amount of high-melting point metal mixed into the semiconductor layer 3 is very small, so the semiconductor layer 3 has a high mobility and a stable threshold value. It becomes possible to form on this semiconductor layer 3 an element suitable for high integration and high speed, which has good characteristics such as the following.

[0018]

EXAMPLES The present invention will be explained in more detail below using examples.

Example 1 FIGS. 2(a) to 2(c) are diagrams showing the manufacturing process of Example 1. In Example 1, after sequentially forming a SiO2 layer 12, a polycrystalline silicon thin film 13 to be annealed, a SiO2 layer 14 as an intermediate layer, and a tungsten film 15 on a single crystal silicon substrate 11, electron The polycrystalline silicon thin film 13 was annealed by beam irradiation.

That is, the single crystal silicon substrate 11 is
LP was heated to 0°C under the conditions of SiH4 gas: 10SCCM, O2 gas: 10SCCM, and pressure 0.13 Torr.
Approximately 1.0 μm is deposited on single crystal silicon substrate 11 by CVD method.
A SiO2 layer 12 of m thickness was formed (see FIG. 2(a)).

[0021] Next, the single crystal substrate 11 is heated to 630°C, SiH4 gas: 20SCCM, pressure 0.13 Torr.
Approximately
A polycrystalline silicon thin film 13 with a thickness of 000 Å is deposited, and a SiO2 layer 14 with a thickness of approximately 500 Å is formed thereon under the above conditions.
Furthermore, a tungsten film 15 of about 0.2 μm was deposited on the SiO2 layer 14. Thereafter, the electron beam BM was irradiated and scanned from above to anneal the polycrystalline silicon thin film 13 and recrystallize it (for example, to form a single crystal) (FIG. 2
(see (b)). At this time, the single crystal silicon substrate 11 is heated to a temperature of 500°C, and the acceleration voltage of the electron beam is set to 10Ke.
V, and the beam current was 2 mA.

After recrystallizing the polycrystalline silicon thin film 13 using an electron beam in this manner, the tungsten film 15 and SiO2 film 14 on the crystallized silicon thin film 13 are removed, and a MOS transistor is formed on the crystallized silicon thin film 13. A device was formed (see FIG. 2(c)). That is, a gate insulating film 19 and a gate electrode 18 are formed on a crystallized silicon thin film 13.
, and further selectively etches predetermined portions of the insulating film 16 to form predetermined portions 13a, 13 of the crystallized silicon thin film 13.
dope with n-type impurities, and a source electrode 17a is placed on top of it.
, a drain electrode 17b was formed to form a MOS transistor element.

The MOS transistor element thus produced has a channel region 13c made of a high-quality crystallized semiconductor, so it has high mobility characteristics, can be operated at high speed, and has a high melting point. Since the amount of metal mixed in was small, there was little variation in the threshold value and stable characteristics were obtained, resulting in extremely good characteristics.

Example 2 FIG. 3 is a diagram for explaining the manufacturing process of Example 2. In Example 2, a polycrystalline silicon thin film 13 of about 5000 Å was deposited on a quartz glass substrate 20 under the same conditions as in Example 1, and SiH2C was deposited on this polycrystalline silicon thin film 13.
l2 gas: 15SCCM, NH3 gas: 150SCCM
, a Si3N4 film 21 of about 500 Å is formed by the LPCVD method at a pressure of 0.45 Torr, and then a Si3N4 film 21 of about 500 Å is formed.
A tungsten film 15 of about 0.2 μm was deposited on the 4 film 21. Thereafter, the polycrystalline silicon thin film 13 was recrystallized by irradiating and scanning the electron beam BM from above.

After recrystallizing the polycrystalline silicon thin film 13 using an electron beam in this manner, the tungsten film 1
5. Remove the Si3N4 film 21 and replace the crystallized silicon thin film 1
When a MOS transistor element similar to that shown in FIG. 2(c) is formed on Embodiment 3, the M
An OS transistor element could be obtained.

[0026]

[Effects of the Invention] As explained above, according to the present invention,
Since an intermediate layer is formed between the semiconductor layer and the high melting point metal film, a high quality semiconductor crystal layer can be easily created by irradiation with energy beam without mixing high melting point metal etc. By forming an element on this semiconductor crystal layer, an element having excellent characteristics such as high mobility and stable threshold value can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a method for manufacturing a semiconductor crystal layer of the present invention.

FIGS. 2(a) to 2(c) are diagrams showing steps of creating a semiconductor crystal layer on a silicon substrate.

FIG. 3 is a diagram for explaining a process of creating a semiconductor crystal layer on a quartz glass substrate.

FIG. 4 is a diagram for explaining a conventional method for manufacturing a semiconductor crystal layer.

[Explanation of symbols]

1 Substrate 2 Insulating layer 3 Semiconductor layer 4 Intermediate layer 5 High melting point metal film BM Energy beam (electron beam) 11
Single crystal silicon substrate 12 SiO2 film 13 Polycrystalline silicon thin film 13a Source impurity layer 13b Drain impurity layer 13c Channel region 14 SiO2 film 15 as an intermediate layer
Tungsten film 16 Insulating film 17a Source electrode 17b Drain electrode 18 Gate electrode 19 Gate insulating film 20 Quartz glass substrate 21 Si3N4 film

Claims (1)

[Claims] 1. When forming a semiconductor layer to be annealed on a substrate and forming a high melting point metal film on the semiconductor layer, an intermediate layer is formed between the semiconductor layer and the high melting point metal film. , after forming the intermediate layer and high melting point metal film on the semiconductor layer,
A method for manufacturing a semiconductor crystal layer, characterized in that an energy beam for annealing the semiconductor layer is irradiated from the high melting point metal film side.