JPH0458525A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture this device without leaving a silicon lump on an insulating film by a method wherein a growth process and an etching process are provided and a polycrystalline silicon thin film is grown selectively only inside a contact hole which is opened in the insulating film with which a substrate to be grown is covered. CONSTITUTION:A single-crystal silicon substrate 9 is covered with a silicon oxide film 10. While a wafer having a contact hole 11 exposing the single-crystal silicon substrate 9 is used, a polycrystalline silicon film 12 is deposited selectively on the single-crystal silicon substrate 9 inside the contact hole 11. At this time, an etching operation is executed in order to remove silicon lumps 13 on the silicon oxide film 10. A growth process and an etching process which are described above are repeated two times. Thereby, it is possible to realize a perfect selective polycrystalline silicon growth operation by which the polycrystalline silicon film 12 is grown only inside the contact hole 11.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and in particular, a method for selectively burying polycrystalline silicon in an opening on a silicon substrate, such as filling a contact hole. It is about the method.

[Conventional technology]

Selective polycrystalline silicon growth is a growth method in which a polycrystalline silicon film 12 is deposited on silicon 19 in a contact hole 11 formed in an insulating film 18 covering a substrate to be grown, as shown in FIG. It is important as a flattening technique for drawing out wiring such as transistor emitters and filling contact holes.

Selective polycrystalline silicon growth is performed by depositing polycrystalline silicon 12 by thermally decomposing silane-based scum such as dichlorosilane (S iH2Cl 2 ) or reducing it with hydrogen (H2), while at the same time depositing only silicon on the insulator 118. This can be achieved by flowing hydrogen chloride (HCI) in an appropriate manner to etch the etching process.

This takes advantage of the fact that the etching speed of polycrystalline silicon is different depending on whether the base is insulating GIA or silicon 19. By appropriately selecting the flow rate of hydrogen chloride, polycrystalline silicon on silicon 19 in contact hole 11 can be etched. silicon 12
However, the etching conditions can be applied to the silicon deposited on the insulating film 18. However, the range of conditions for complete selectivity such that polycrystalline silicon 12 grows only in the contact hole 11 is narrow, so the insulation [
At present, it is difficult to leave no silicon on 18.

[Problem to be solved by the invention]

The conventional selective polycrystalline silicon growth described above has the problem that it is not possible to achieve complete selective growth, and silicon lumps are scattered on the insulating film. This spacing is particularly noticeable when growing a thick polycrystalline silicon film, and as the film is grown for a long time, many silicon lumps exist on the insulating film, making it difficult to maintain selectivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that realizes completely selective polycrystalline silicon growth without leaving any silicon lumps on an insulating film.

[Means to solve the problem]

In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention includes a growth step and an etching step, and forms a polycrystalline silicon thin film only in a contact hole opened in an insulating film covering a growth substrate. A method for manufacturing a semiconductor device in which polycrystalline silicon is selectively grown in the contact hole by simultaneously flowing a growth gas and an etching gas in the growth step, and in the etching step, a growth gas and an etching gas are flowed simultaneously. This method removes only the silicon on the insulating film by flowing it, and the growth step and the etching step are performed in alternating combinations, and this combination allows the film to grow only in the contact hole. be.

[Effect]

The selective polycrystalline silicon growth of the present invention includes a process of performing an etching process by flowing only hydrogen chloride (HCl) in addition to a growth process using a conventional growth method, and a film is grown by alternately combining these processes. 2 [Example] Next, the present invention will be described with reference to the drawings.

(Example 1) FIG. 1 shows a vapor phase growth apparatus used for forming various films such as polysilicon. A cylindrical dome-shaped quartz furnace core tube with a double structure of vertically long inner and outer tubes 1.2 is arranged on the pedestal 3 to process several dozen growth substrates 4 in one growth. It is surrounded by a resistance heating furnace 6.

At the center of the inner tube 2, a substrate holder 5 holds the growth substrates 4 so as to be stacked horizontally at certain intervals. The lower end center axis of the board holder 5 extends to the bottom of the pedestal 3,
It is designed to be able to rotate around the central axis at the bottom end.
From below the frame 3, a vertically long thin gas introduction pipe 7 connects to the inner pipe 2.
It extends along the wall, and from the gas introduction pipe 7, silane-based gas such as dichlorosilane (S iH2CI2),
Hydrogen (H2) is released toward each growth substrate 4 to selectively grow a polycrystalline silicon film thereon. The dregs not involved in the growth are exhausted through the dregs discharge hole 8.

As a growth substrate 4 as shown in FIG.
Contact hole 1 in which single crystal silicon 9 with a size of 1 μm×1 μm is exposed in silicon oxide [10]
A wafer provided with No. 1 was used.

The pressure during growth was 30 TOrr, the temperature was 800°C, 3003 CC11 of dichlorosilane, and 150 se of hydrogen chloride.
ci for 15 minutes to selectively form a polycrystalline silicon film 12 on the single crystal silicon 9 in the contact hole 11 at 10 onI.
N was deposited. However, as shown in FIG. 2(b), some silicon lumps 13 remain on the silicon oxide film 10, and in order to remove them, dichlorosilane is partially stopped and only hydrogen chloride is added at 300 sccn m. then 15
Etching was performed for a minute. Contact hole 1
Only the silicon lump 13 on the silicon oxide film 1Q was etched and removed without etching the polycrystalline silicon film 12 in the silicon oxide film 1Q.

As described above, complete selective polycrystalline silicon growth with a film thickness of 100 nm was realized by a single combination of the growth process and the etching process (FIG. 2(C)).

It is difficult to remove the silicon lumps 13 scattered on the silicon oxide film 10, which is an insulating film, by etching them once they have grown to a large size, but they can be removed by flowing an etching gas in the early stage of growth. It was easily removed. Furthermore, by repeating the combination of these growth steps and etching steps twice, we were able to achieve either 200nm polycrystalline silicon@12 or completely selective polycrystalline silicon growth that grows only within the contact hole 11 (second step). Figure (d
)).

(Example 2) Figures 3(a) to (1) show a growth substrate 4 having a multilayer structure.
This is an example used in the following. In Figure 3(a),
The growth substrate 4 is a single crystal silicon substrate 9, and from the bottom, silicon oxide M14-100nn, polycrystalline silicon! !
g! 15-100nn, silicon oxide M1G-40O
After depositing four layers of nitride film 17 to 100 nn, contact hole 11 is opened to expose polycrystalline silicon [5] through nitride film 17 and silicon oxide film 16. This structure is based on TPT (Thin F), which is a transistor whose operating region is polycrystalline silicon.
ilmTransistor) wiring contact. Further, as the insulating film, a silicon oxide film was used in Example 1, whereas a nitride film was used in Example 2.

Polycrystalline silicon 1912 is nitrided onto this growth substrate 4.
In 17, an attempt was made to selectively grow the inside of the contact hole 11 by 300 nl on the polycrystalline silicon film 15 without growing it. The same equipment as in Example 1 was used, and the pressure was also the same as in Example 1, 30 Torr.

First, add 300scc of dichlorosilane at a temperature of 800°C.
n, flowing hydrogen chloride at 150scci for 15 minutes, polycrystalline silicon Wj! 12 was deposited in the 100n-th contact hole 11 (FIG. 3(b)). Next, the dichlorosilane was stopped, and only hydrogen chloride was flowed at 600 scci for 10 minutes to etch the silicon lump 13 on the nitride film 17.
We achieved selective polycrystalline silicon growth that completely fills only the contact hole 11 of the polycrystalline silicon shank 12 (see Figure 3 (C).
)).

In Example 2, unlike in Example 1, the growth time was shortened by increasing the flow rate of hydrogen chloride in the etching step. Polycrystalline silicon J12 of 90 nIN could be grown in this one cycle of 25 minutes. To explain the selectivity, only when the insulating film is a silicon oxide film, Extended Abs
tracts of the 18th Conference
ence onSolid 5tate Device
s and Materials, 1986. pp
49-52, which states that silicon deposited on a silicon oxide film reacts with the silicon oxide film to form SiO and escapes into the gas phase, so no silicon is deposited on the silicon oxide film. There is. However, in the case of Example 2, a nitride film is used as the insulating film, and it was found that selective polycrystalline silicon growth can be achieved even if the insulating film is not a silicon oxide film.

300nl polycrystalline silicon film 1 in contact hole 11
2 can be achieved by repeating the cycle three times (Figure 3(d)).

In the above examples, the case where dichlorosilane was used as the selective polycrystalline silicon growth gas was described, but monosilane (S I H4), disilane (Si2H6)
It could be gas. Also, the temperature during growth and the temperature during etching do not necessarily have to be the same;
[Effects of the Invention] As explained above, by using the present invention, it is possible to completely select polycrystalline silicon without leaving silicon lumps on the insulating film, which has been a problem in the past. We were able to achieve growth. Also,
The present invention has made it possible to selectively grow polycrystalline silicon over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a vapor phase growth apparatus for selective polycrystalline silicon growth used in the present invention, and FIG. 2 (a) is a cross-sectional view showing a part of the growth substrate used in Example 1 of the present invention. , second
Figure (b) is a cross-sectional view showing the state after the first growth process in Example 1 of the present invention, and Figure 2 (C) is a cross-sectional view showing the state after one cycle of the growth process and etching process in Example 1. ((1) is a cross-sectional view showing the state in which the selective polycrystalline silicon growth of Example 1 is completed; FIG. 3(a)
3(b) is a sectional view showing a part of the growth substrate used in Example 2 of the present invention, and FIG. 3(b) is a sectional view showing the state after the first growth step in Example 2 of the present invention. Figure 3 (C)
3(d) is a cross-sectional view showing the state after completing one cycle of the growth process and the etching process in Example 2, and FIG.
FIG. 4 is a cross-sectional view showing general selective polycrystalline silicon growth. 1... Outer tube 2... Inner tube 3... Frame 4... Growth substrate 5... Substrate holder 6... Resistance heating furnace 7... Gas introduction tube
8... Gas exhaust hole 9... Single crystal silicon substrate 10... Silicon oxide film 12... Polycrystalline silicon film 14... Silicon oxide film 16... Silicon oxide film 18... Insulating film 11...Contact hole 13...Silicon lump 15...Polycrystalline silicon film 17...Nitride film 19...Silicon patent applicant NEC Corporation Representative Patent attorney Kanno Nakao Diagram 4-value bottom long chart

Claims (2)

[Claims] (1) A method for manufacturing a semiconductor device, which comprises a growth step and an etching step, and selectively grows a polycrystalline silicon thin film only in a contact hole opened in an insulating film covering a substrate to be grown, the growth step comprising: , polycrystalline silicon is selectively grown in the contact hole by simultaneously flowing a growth gas and an etching gas, and the etching process is a process in which only the silicon on the insulating film is removed by flowing the etching gas. A method for manufacturing a featured semiconductor device. (2) The growth step and the etching step are performed in alternating combinations, and this combination allows the film to grow only within the contact hole. A method for manufacturing a semiconductor device.