JPS62203360A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture a highly reliable capacitor by a method wherein the bottom of a groove cut in a semiconductor substrate is implanted with oxygen ion and then a thermal oxide film for capacitor is formed to be filled with polysilicon. CONSTITUTION:A silicon oxide film 2 is formed on a P-type Si (100) substrate 1. A capacitor forming region is not covered with the film 2. The substrate 1 is etched using the film 2 as a mask to make an opening 3. An ion-implanted layer 4 is formed by implanting boron in the bottom of opening 3. First, an oxygen-implanted layer 5 is formed on the bottom of opening 3. Second, the oxygen-implanted layer 5 is heat-treated to be converted into a silicon oxide film 6. The opening 3 is obliquely implanted with ion to form another implanted layer 7 on the sidewalls. The implanted layer 7 is oxidized in oxygen atmosphere to form another oxide film 8. Finally, a capacitor can be formed by filling the opening 3 with polysilicon 9 as an electrode.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method of manufacturing a high-density semiconductor device.

BACKGROUND OF THE INVENTION Various types of trenched capacitors have been proposed. For example, M, Wada.

K, Hieda, S, Watanabe, 'Afolded Capacitor Cell (F, C, C0) Fore Mega Pit DRA
MS'IEDM (M, Wada, Ni, Hie)
da, S, Watanabe.

”A Folded Capacitor Ce1l
(F, C, C,) ForMegabit DRAM
S'IEDM) p, 244 1984, etc.

As shown in FIG. 2, a groove is first dug in the silicon substrate 11, then boron ions are implanted for element isolation, and the groove [S102] is filled by the CVD method. For the peripheral 0M03 circuit, n-wθ11 is formed and then etched back to leave the SiO2 film 16 of the required thickness. Then, thermal oxidation for the capacitor is performed to fill the polysilicon 17.

Problems to be Solved by the Invention In the prior art, the thickness of the S 102 obtained by etch packs varied, and it was sometimes difficult to form deep grooves.

Means to Solve the Problems In order to solve the above problems, the present invention injects oxygen ions into the bottom of a groove formed in a semiconductor substrate, and then forms a thermal oxide film for a capacitor as usual and embeds polysilicon. A capacitor is produced by this.

The bottom surface of the working capacitor is an oxide layer formed by oxygen ion implantation and heat treatment, so there is no electric field concentration in this area. Furthermore, during sidewall ion implantation, these ions can be prevented from accumulating in the substrate portion at the bottom of the groove. This allows a highly reliable capacitor to be produced.

Embodiment FIG. 1 is a process sectional view showing an embodiment of the present invention. In FIG. 1(a), numeral 1 is a P-type silicon (100) substrate with a resistivity of about 10 Ω, and numeral 2 is a silicon oxide film produced by the CVD method. The silicon oxide film does not cover the area where the capacitor will be made. This silicon oxide film is etched,
This serves as a mask for ion implantation. Figure 1 (b
), the silicon substrate is etched using a silicon oxide film as a mask to form an opening 3. In (c), a poron was driven into the bottom of the opening as a channel stopper. 4 is an ion implantation layer. (C) The figure shows oxygen ion implantation at the bottom of the opening.5. Form an oxygen implantation layer. 5. Next, heat treatment is performed in a furnace as shown in the figure (e). The oxygen injection layer is 6. It becomes a silicon oxide layer.

In the figure (f), oblique ion implantation is performed into the opening to form an implanted layer on the side surface. Next, (q) 8. is oxidized in an oxidizing atmosphere as shown in the figure. Forms an oxide layer. This thickness, which determines the capacitor capacity, is several hundred angstroms
It is about 100 angstroms. Next, a capacitor is formed by filling the electrode 9 with polysilicon.

Effects of the Invention According to the present invention, an oxide film is formed at the bottom of the trench capacitor, where electric field concentration tends to occur in the past, which is stronger than on the other side surfaces, so that electric field concentration does not occur. Therefore, a highly reliable capacitor can be formed. In addition, since reflected ions during side implantation are stopped at the silicon oxide layer, the effect of the channel stopper ions is not negated.

[Brief explanation of drawings]

FIG. 1 is a process sectional view for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a process sectional view for explaining a conventional manufacturing method. DESCRIPTION OF SYMBOLS 1... P-type silicon substrate, 2... Silicon oxide film, 3... Opening, 4... Ion implantation layer, 6...・Oxygen injection layer, 6...
・Oxide layer, end...Injection layer, 8...Oxide film, 9...Polysilicon. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1 Figure 2 Figure 2 13 Opening area 17 tsubo

Claims (1)

[Claims] a step of providing a mask material in a portion of the semiconductor substrate other than the capacitor region; a step of etching the semiconductor substrate to form a groove; a step of implanting channel stopper ions into the semiconductor substrate, and then implanting oxygen ions; A method for manufacturing a semiconductor device, comprising the steps of heat treating the semiconductor substrate, heat treating the semiconductor substrate in an oxidizing atmosphere, and forming a buried conductor layer.