JPS5934640A - Heat treatment device by electron beam - Google Patents

Abstract

PURPOSE:To make a temperature at a center lower than that of the periphery, and to enable to form a silicon layer of a super-coarse crystal grain on an insulating film by forming a plurality of projecting sections to a cathode for an electron gun and deflecting and scanning the electron gun in the vertical direction to the direction of arrangement of a plurality of said projecting sections in the electron-beam heat treatment device used for recrystallizing a semiconductor film. CONSTITUTION:The electron gun 11 is constituted by the cathode 12, a grid 13 and an anode 14. The cathode 12 has a plurality of the projecting sections 15. Electrons emitted from the electron gun 11 are focussed or expanded by an electron lens with a diaphragm 16, and a material to be thermally treated 19 is scanned by a deflection coil 18. The direction of scan of the material is vertical to the direction of arrangement of a plurality of the projecting sections 15. Electron beams are irradiated from an upper section, and the silicon layer 105 is thermally treated. Acceleration voltage is 10KV and beam currents are 10mA at that time. Since a crystal grain boundary has a tendency to disperse and reduce at a central section in the temperature distribution of a melting region of the silicon layer 105, the number of crystal grains decreases gradually, and the super-coarse crystal grain of 20-40mum width and several mm.- several dozen mm.length is obtained in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an electron beam heat treatment apparatus used for recrystallization of semiconductor films and the like.

[Prior art and its problems] In recent years, possibilities have opened up for improving the functionality of energies such as laser light and electron beams, realizing multifunctional devices, and realizing devices with new functions and new structures. According to conventional apparatuses, methods such as heat treatment by beam irradiation are carried out by continuously scanning an energy beam at the same energy and speed. When heat treatment is performed in this manner, the center of the beam has the highest temperature, reflecting the intensity distribution of the energy beam, and the temperature decreases toward the periphery. For example, when melting and recrystallizing a semiconductor film (hereinafter referred to as silicon film) on an insulator using an energy beam, the solid phase 1 and liquid Phase 2 is formed and grain boundaries are concentrated.

During assimilation, the solid-liquid interface lags behind the most at the center of the beam. The reason for this is that the temperature at the center of the beam is the highest and solidification is delayed. During solidification, the direction of grain boundaries is perpendicular to the solid-liquid interface;
At the solid-liquid interface as shown in Figure (a), the grain boundaries become more and more concentrated from the surroundings, making it difficult for the silicon film to become coarse crystal grains or to become single crystal.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in energy beam heat treatment and to provide a synthetic beam heat treatment apparatus that can obtain heat treatment characteristics completely different from conventional ones.

[Summary of the Invention] The present invention provides a plurality of protrusions on the cathode of an electron gun, and performs deflection scanning of the electron gun perpendicular to the arrangement direction of the plurality of protrusions. As shown in the intensity distribution in FIG. 5, the temperature at the center can be lowered compared to the surrounding area.

By performing heat treatment by scanning such an electron beam in the direction of the arrow, it was possible to realize a solid-liquid interface as shown in FIG. 2(b).

Note that the holes in the grid and the anode may be independent, but if the electron gun is designed so that the electron beam can be focused well, they may be connected to form one hole.

[Effects of the Invention] According to the present invention, it is possible to perform heat treatment so that the intensity of the beam increases from the center to the periphery.
It has become possible to form a silicon layer with ultra-coarse crystal grains with a length of several millimeters to several tens of millimeters on an insulating film.

[Embodiments of the Invention] There are a coilament type and an electron impact type shown in (b), in which the emitted electrons are focused or expanded by a 9' lens equipped with an aperture 16, and are further shunted by a deflection coil 18. Heat treated object 1
9 is scanned. This scanning direction is perpendicular to the arrangement direction of the plurality of protrusions 15.

An example in which the apparatus according to the present invention is used to manufacture a two-layer MO8LSI will be described below with reference to FIG. First, Figure 6 (
As shown in a), for example, 5102JJ1 of about 1 μm is deposited on a single crystal silicon substrate 101 with a P-type (100) orientation.
Form 02. On top of that, if necessary, a SiN film 103
form. This SiN film is formed to make it easier to convert a polycrystalline or amorphous silicon layer into a single crystal in a later step. It is also assumed that desired elements have already been formed on the silicon substrate 101 through a well-known process. Next, as shown in FIG. 6(b), a polycrystalline silicon layer 104 of, for example, about 6000 layers is deposited on the surface of the SiN film 103. A Sio2 film 105 of approximately 2000λ is formed thereon. sio at this time. The membrane scans your electron beam in the direction of the arrow in FIG. 4(a).

, the acceleration voltage is 10KV, and the beam current is IOmA.
Met.

According to the apparatus used in the example, the width of the silicon layer melted during the heat treatment was about 1.5 μm. The temperature distribution in this melting region is as shown in Figure 2 (b), and as the grain boundaries tend to disperse and decrease in the center, the number of grain boundaries gradually decreases, and eventually Ultra-coarse crystal grains with a width of 20 to 40 μm and a length of several millimeters to several tens of millimeters were obtained. Furthermore, when the cathode rod was lengthened from side to side to form 3 to 5 protrusions and heat treatment was performed, crystal grains with a melting width of 100 μm and several microns in width began to grow in stripes.

Vacuum degree during heat treatment] Ultra-high vacuum state of 08 Torr or more,
The substrate temperature was 500'O and the silicon substrate was fixed electrostatically. The beam scans in the X direction at a speed of about 100 cm/see, and in the X direction, it scans at W/2 and W in accordance with the melting width W
/4 etc. was sent step by step.

Next, as shown in FIG. 6 (ψ), the 5io2 film 105 is removed and formed, and a gate polarization 108 made of polycrystalline silicon, for example, is formed in the element region via the gate oxide film 107.
Source/drain regions 109 and 110 are formed to form a descendant OS transistor. Next, as shown in FIG. 6(e), after covering the entire surface with an insulating film 111, an electrode 112 formed by hlJ is
114 is formed to complete a three-dimensionally integrated semiconductor device.

[Other Embodiments of the Invention] Using the device according to the present invention, the MOS described in this embodiment can be
In addition to transistors, C-MO! It goes without saying that all kinds of elements such as transistors, bipolar transistors, diodes, etc. can be effectively formed in a heat-treated silicon layer, and by arranging these elements three-dimensionally using the effects of the present invention. , conventionally high integration, ^
It has become possible to realize a high-performance, multi-functional three-dimensional integrated circuit device. By using the device according to the present invention, it is possible to provide a hole in a semiconductor other than silicon, such as germanium, QaAs, Qap, etc. , or these holes may be communicated.

[Brief explanation of drawings]

Figures 1 (a) and (b) are explanatory diagrams showing typical types of cathodes, and Figures 2 (a) and (b) are diagrams showing the occurrence of grain boundaries near the solid-liquid interface according to the conventional method and the present invention. FIG. 3 is a layout diagram showing an embodiment of the present invention, and FIG. 4 (a) shows the state.
) to (d) are perspective views showing examples of the shape of the shade and moat, FIG. 5 is a beam intensity distribution characteristic diagram according to the present invention, and FIG. 6 (a) to (e
) is a cross-sectional view of the process showing an example of applying the Kinoi □, Akira device to an integrated circuit. Nido...'d electron, 12... cathode, 17... electron lens, 18... deflection coil, 19... object to be heat treated. 15... Protrusion. Applicant Makoto Ishizaka, Director General of the Agency of Industrial Science and Technology - No. 1
Figure ((1) (b) Figure 2 Figure 3 @ Figure 6 Figure 6

Claims (1)

[Claims] An electron gun composed of a cathode, an anode, and a grid, a lens system that focuses or expands the electron beam emitted from the electron gun, and a deflection means that scans the electron beam that has passed through this lens system and heat-treats the object to be heat-treated. An electron beam heat treatment apparatus, characterized in that the 'd electron gun cathode has a plurality of protrusions, and the deflection means scans perpendicularly to the arrangement direction of the plurality of protrusions.