JPS63246813A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To improve quality of a silicon layer recrystallized on an insulation layer and reduce the amount of oxidation for insulation by forming an extremely thin polycrystalline silicon layer on a seed part and then recrystallizing the polycrystal silicon layer. CONSTITUTION:A polycrystalline silicon layer 5 is formed on Si3N4 film 4 in the thickness of 0.5 mum, the polycrystalline silicon layer 5 on a seed part 2 is removed by etching and thereafter a thin polycrystalline silicon layer 6 of about 0.2 mum is deposited on the seed part 2 and polycrystalline silicon layer 5. Next, the polycrystalline silicon layers 5, 6 are irradiated with laser or elec tron beam for melting and recrystallization. Here, the polycrystalline silicon layer 6b on the oxide film 3 other than the seed part 2 recrystallizes the polycrystalline silicon layer 5 with the recrystal having good crystal property on small seed part 2 considered as a seed crystal and therefore a recrystallized layer having good crystal property can be obtained. Accordingly, recrystallization of polycrystal silicon on the seed part can be obtained with good property and the crystal property of single crystal silicon to be recrystal lized in the lateral direction can be improved.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is based on 5ol (Silicon On In5ura).
The present invention relates to an improvement in a method for recrystallizing a silicon layer in a semiconductor device having a tor) structure.

[Prior art]

Conventionally, as a method for recrystallizing a silicon layer in a semiconductor device with an S old structure, a seed part is left on a single-crystal silicon substrate where single-crystal silicon, which will become a seed crystal during recrystallization, is exposed, and the remaining part is covered with an insulating layer such as 5iOi. A method has been considered in which after forming a polycrystalline silicon layer, a polycrystalline silicon layer is deposited on the window portion and the insulating film, and the polycrystalline silicon layer is recrystallized. Then, an active layer such as a transistor is formed by diffusion or the like in the single crystal silicon layer obtained by this recrystallization.

[Problems to be solved by the invention]

However, in the conventional recrystallization method, it is possible to uniformly form an active layer on the seed part and the insulating layer.
．． A polycrystalline silicon layer is formed to the thickness of 7 skins, then the thick polycrystalline on the seed part is recrystallized at once, and then the polycrystalline silicon on the insulating layer is laterally recrystallized. Therefore, strain is likely to occur on the seed portion, and the strain generated on the seed portion propagates laterally, degrading the quality of the active layer. Furthermore, there is a problem in that the amount of oxidation performed to insulate the substrate and the recrystallized layer increases. The present invention has been made to solve the above problems, and its purpose is to improve the quality of the silicon layer recrystallized on the insulating layer and to provide insulation. The goal is to reduce the amount of oxidation that takes place.

[Means to solve the problem]

The structure of the invention for solving the above problems is to leave a seed part that becomes a seed crystal during recrystallization on the main surface of a single crystal silicon substrate, and form an insulating layer in the remaining part, and to form a multilayer film on the seed part and the insulating layer. In a method of manufacturing a semiconductor device in which a crystalline silicon layer is formed and the polycrystalline silicon layer is recrystallized, an extremely thin polycrystalline silicon layer is formed on at least the seed portion, and the polycrystalline silicon layer is formed on the seed portion. It is characterized by horizontal recrystallization from a polycrystalline silicon layer.

[Effect]

In the method of the present invention, the polycrystalline silicon layer deposited on the seed part is formed extremely thin as described above, so that the polycrystalline silicon on the seed part is recrystallized with high quality, and the polycrystalline silicon layer deposited on the seed part is recrystallized with high quality. The crystallinity of single crystal silicon to be crystallized is improved.

【Example】

The present invention will be described below based on specific examples. FIG. 1 is a sectional view showing the structure of a semiconductor element in each manufacturing process of the method of the first embodiment. In FIG. 1 (a>, 1 is a single crystal silicon substrate,
On the main surface, an oxide film (SiO=) 3 with a thickness of 1 μm is formed as an insulating layer by Locos oxidation, except for the seed portion 2 which will serve as a seed crystal during recrystallization. Then, the oxidation [3 has a thickness of 60 people S+aN4#
4 is formed on the entire surface by the LPCVD method. Next, the first
0.5μ on 5isN4WX4 as shown in figure (b)
A polycrystalline silicon layer 5 is formed to a thickness of m. and,
As shown in FIG. 1(C), after applying a resist on the polycrystalline silicon layer 5 and removing the resist in the portion corresponding to the seed portion 2 by photolithography, the polycrystalline silicon layer 5 is deposited on the seed portion 2. Layer 5 is removed by etching. Here, SI3 on the oxide film (Si port) 3
The N4 film 4 is used to improve the wettability between Si and the Si opening during annealing, and the 5isN4 film on the seed part 2
#4 serves to protect the single crystal seed portion 2 when the polycrystalline silicon layer 5 on the seed portion 2 is etched. Next, as shown in FIG. 1(d), 5158 on the seed part 2 is
4M4 is removed by etching with hot phosphoric acid, and as shown in FIG. Deposit on silicon layer 5. This thin polycrystalline silicon layer 6
It is not necessary to form the polycrystalline silicon layer 6a on the entire surface of the previously formed polycrystalline silicon layer 5 as long as the polycrystalline silicon layer 6a formed on the seed portion 2 is bonded to the polycrystalline silicon layer 5. next,
As shown in FIG. 1(f), the polycrystalline silicon layer 5.6 is irradiated with a laser or an electron beam to melt and recrystallize it. At this time, among the melted polycrystalline silicon layers 6, the flow of heat from the thin polycrystalline silicon FFs 6a on the seed portion 2 to the single crystal silicon substrate 1 is large, so the thin polycrystalline silicon layers 6a solidify first. , grain boundaries are less likely to occur in that part because it is thin. Therefore, the polycrystalline silicon layer 6b other than on the seed part 2 (on the oxide film 3) has good crystallinity and can recrystallize the polycrystalline silicon layer 5 using the small recrystallization on the seed part 2 as a seed crystal. A recrystallized layer with good crystallinity can be obtained. Note that especially good results can be obtained when the thickness of the polycrystalline silicon layer 6a formed on the seed portion 2 is set to be less than half the thickness of the recrystallized layer serving as the active region. Active elements and the like are formed on this recrystallized layer, and one method will be described with reference to FIG. 2. As shown in FIG. 2(a), a recrystallized layer 7 is formed on the oxidized layer 7, and elements such as transistors are formed in the recrystallized layer 7, but the part where it is formed is isolated. Therefore, insulating layers 8a and 8b are formed around them by Locos oxidation.
is formed. At this time, since the thickness of the polycrystalline silicon layer 6a on the seed portion 2 is thinner than that in the conventional case, the amount of oxidation of the insulating layer 8a can be reduced accordingly. Next, as shown in Figure 2(b), phosphorus was heated to 150 keV.
Ion implantation is performed by 1×10”doae to 5×10I2dose to form an N-type well layer 71. Then, as shown in FIG. Form oxide M9. Next,
On the gate oxide film 9, doped polycrystalline silicon with a thickness of approximately 3500 nm is deposited, a resist is applied, the resist is removed from areas other than the gate portion by photolithography, and then etched as shown in FIG. 2(d). A polycrystalline silicon gate 10 is then formed. Next, as shown in FIG. 2(e), a resist is placed on the polycrystalline silicon gate 10 and the gate oxide film 9, and after removing the resist in the source and drain portions by photolithography, boron is irradiated at 25 keV. Input only X 10”dose,
A P-type source 11 and a P-type drain 12 are made. Next, the second
IIPSGF! on top of the surface layer as shown in figure (,f)!
13 to a thickness of about 7,000 people. Then the ll
A resist is placed on the PSG layer 13, and the resist is removed only from the portion where the contact hole is to be formed by photolithography, the contact hole 14 is formed by etching, and the oxide film 9 under the contact hole 14 is also removed by etching. After that, as shown in FIG. 2(g), Al-5
i to a thickness of approximately 1.0 μm by sputtering to form electrode 1.
At the same time, a resist is applied on the Al-5i vapor deposited layer, the resist is removed from areas other than those necessary for wiring by photolithography, and an aluminum wiring layer is formed by etching. Next, a second embodiment will be explained. As shown in FIG. 3(a), an oxide film 3 is formed on the silicon substrate 1 by Locos oxidation, which is thin on the seed portion 2 and thick on other portions. after that,! As shown in FIG. 3(b), a polycrystalline silicon layer 5 is deposited on the oxide film 3, and as shown in FIG. 3(c), the polycrystalline silicon layer 5 located above the seed portion 2 is etched. be done. In the first embodiment, 513N4 Ml was used as a seed protective film during etching of the polycrystalline silicon layer 5, but here the oxide film 3 on the seed portion 2 is used as a protective film. Next, the third
As shown in FIGS. 3(C) and 3(d), after removing the oxide film 3a on the seed portion 2 by etching, as shown in FIG.
A thin polycrystalline silicon layer 6 having a thickness of about 0.1 μm is formed as shown in FIG. Thereafter, polycrystalline silicon layers 5 and 6 are melted and recrystallized similarly to the vJ1 embodiment. The method of this embodiment is an effective method when Si and N4 films cannot be used. Next, a third embodiment will be described. As in the first embodiment, as shown in FIG. 4(a), the remaining surface of the single crystal silicon substrate 1, leaving the seed portion 2, is subjected to Locos oxidation to form oxidation [3]. Then, a polycrystalline silicon layer 5 having a thickness of about 0.6 μm is formed on the oxide film 3. Next, as shown in FIG. 944(b), an oxidized portion 51 is formed by Locos oxidation so that the polycrystalline silicon layer 5 on the seed portion 2 remains thin. Next, as shown in FIG. 4(c), this oxidized portion 51 is removed by etching 5I02 to form a thin polycrystalline silicon layer 5 above the seed portion 2. Then, as shown in FIG. After that, manufacturing can be carried out in the same manner as in the first embodiment. Next, a fourth example will be described. As shown in FIG. 5(a), the main surface of the single crystal silicon substrate 1 is oxidized to a thickness of about 1 μm by Locos oxidation. 3, and the oxide film 3 above the seed part 2 is 5 inches thick.
The seed part 2 and the oxide film 3 are exposed by etching.
A thin polycrystalline silicon layer 20 having a thickness of about 0.1 μl is formed thereon, and the thin polycrystalline silicon layer 20 is recrystallized by laser irradiation. Next, as shown in FIG. 5(b), a thin polycrystalline silicon layer 21 with a thickness of approximately 0.1 μm is formed on the recrystallized recrystallized silicon layer 2Oa, and this polycrystalline silicon layer 21 is formed by laser irradiation. The silicon layer 21 is recrystallized. This process is repeated to obtain a single crystal silicon layer having a thickness sufficient to form an active layer such as a transistor. In the above method, since the polycrystalline silicon layer 20 that is first recrystallized is formed thinly, when this polycrystalline silicon layer 20 is recrystallized, distortion and grain boundaries are less likely to occur, resulting in improved crystallinity. will improve. Furthermore, when further depositing polycrystalline silicon on the recrystallized silicon FJ 2 Oa obtained by recrystallizing the polycrystalline silicon layer 20 and recrystallizing it, the entire recrystallized silicon layer becomes a seed. crystallinity improves. Furthermore, when a single crystal silicon layer is further formed on the recrystallized silicon layer 2Oa, single crystal silicon may be epitaxially grown thereon using the recrystallized silicon Ji 320a as a seed.

【Effect of the invention】

As described above, in the present invention, the polycrystalline silicon layer formed on the seed part is formed extremely thin and the polycrystalline silicon layer is recrystallized, so that recrystallization starts from the thin polycrystalline silicon layer. This prevents grain boundaries and distortion from occurring. In addition, the recrystallization on the highly crystalline seed part becomes a seed,
Since recrystallization progresses in the lateral direction, the crystallinity of the single crystal silicon layer obtained by recrystallization is improved.

[Brief explanation of drawings]

FIGS. 1(a) to 1(f) are cross-sectional views of a semiconductor element at each step of a manufacturing method according to a specific embodiment of the present invention. FIGS. 2(a) to 2(g) are cross-sectional views of a semiconductor device in each step of one method for forming active devices and the like on a recrystallized layer. FIGS. 3(a) to 3(e) are cross-sectional views of a semiconductor element at each step of the manufacturing method according to the second embodiment. FIGS. 4(a) to 4(c) are cross-sectional views of a semiconductor element in each step of the manufacturing method according to the third embodiment. FIGS. 5(a) and 5(b) are cross-sectional views of the semiconductor element at each step of the manufacturing method according to the fourth embodiment. 1...Single crystal silicon substrate 2...Seed part 3
°Oxidation [(Si port 2) 4 ・Si, N4 film 5.
6° Polycrystalline silicon FJ9°°°゛Gate oxide film 1
0 - Polycrystalline silicon gate 11 - P type drain 12° - P type source 13 - PBSG layer 15 - Electrode 20a ° - Recrystallized silicon layer 51 - Oxidation part Patent applicant Nippondenso Co., Ltd. Agent Patent attorney Osamu Fujitani Figure 3 Figure 5 (c)

Claims (3)

[Claims] (1) Leaving a seed portion to serve as a seed crystal during recrystallization on the main surface of a single-crystal silicon substrate, forming an insulating layer on the remaining portion, forming a polycrystalline silicon layer on the seed portion and the insulating layer, and forming a polycrystalline silicon layer on the seed portion and the insulating layer. In a method for manufacturing a semiconductor device in which a crystalline silicon layer is recrystallized, an extremely thin polycrystalline silicon layer is formed on at least the seed portion, and recrystallization is performed laterally from the polycrystalline silicon layer formed on the seed portion. A method for manufacturing a semiconductor device, characterized by crystallization. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the polycrystalline silicon layer formed on the seed portion is formed thinner than the polycrystalline silicon layer formed on the insulating layer. . (3) The polycrystalline silicon layers formed on the seed portion and the insulating layer are formed extremely thinly to the same thickness, and the polycrystalline silicon layer is recrystallized, and the recrystallized single crystal silicon layer is 2. The method of manufacturing a semiconductor device according to claim 1, further comprising forming polycrystalline silicon as a seed on the single crystal silicon layer and recrystallizing it.