JPH0521357A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To rapidly manufacture a thick grown layer by a selective vapor epitaxial growth with an insulating film as a mask. CONSTITUTION:This method comprises the steps of growing epitaxially grown layers 5-8 selectively grown on an exposed surface of a substrate 1 within a latent period in which deposition of silicon does not occur on an insulating film 2 repeatedly a plurality of times through growth pausing periods to form a grown layer 9 having a desired thickness. During the pausing period, at least one of a step of irradiating with an ultraviolet ray, a step of holding a growing atmosphere under a pressure of 1/10,000 of the growing time and a step of holding it at a high temperature higher by 100 to 200 deg.C than that at the time of growing the substrate 1, is conducted, mixture gas of Si2H6 and hydrogen is used as a material, and held in hydrogen containing 0.1-10% of fluorine or chlorine during the pausing time. A period from the start of growing to a time point of rapidly increasing an Auger spectroscopic spectrum of Si on the surface of the insulating film is previously measured, and the period is formed as the latent period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing method, and more particularly to selective vapor phase epitaxial growth of silicon using an insulating film as a mask.

The selective epitaxial growth method for directly forming a desired shape during crystal growth is widely used today as an important technique for manufacturing a complicated and fine semiconductor device. However, the growth rate by the selective growth method is slow, and it is not easy to manufacture a thick epitaxial growth layer.

Therefore, there is a need for a method for growing a selective epitaxial crystal pattern having a desired film thickness quickly and reliably.

[0004]

2. Description of the Related Art Selective growth is carried out under the condition that silicon is not deposited on an insulating film serving as a mask and at the same time silicon is epitaxially grown on a surface where a silicon crystal is exposed.

Conventionally, in order to prevent generation of growth nuclei of silicon on an insulating film and realize selective growth satisfying the above conditions, HCl gas for etching growth nuclei is mixed, or a pressure lower than that of a normal CVD method is used. ULPC growing below
The VD (Ultralow pressure CVD) method was used.

However, in these conventional methods, the growth rate is slower than that of ordinary CVD because the supply of the source gas is small. Therefore, it took a long time to grow a thick epitaxial layer.

Further, when the growth time is long, it is not possible to prevent the deposition of silicon on the insulating film, so that it is impossible to form a thick epitaxial growth layer which requires a long time by the selective growth method.

Therefore, as a method of preventing the deposition of silicon on the insulating film with a high growth rate, a method using the sputtering method together has been devised. This method inhibits the deposition of silicon on the insulating film by sputtering the silicon on the insulating film.

However, since the epitaxial growth surface is also sputtered, the growth surface may be damaged and the quality of the epitaxial growth layer may be degraded.

[0010]

As described above, the conventional selective epitaxial growth has a drawback that the growth rate is slow and there is a problem that a thick epitaxial layer cannot be grown.

Further, in the method in which the growth rate is improved by using the sputtering method to enable thick growth, the quality of the epitaxial growth layer may be deteriorated. An object of the present invention is to provide a method for manufacturing a semiconductor device capable of rapidly manufacturing a thick selective vapor phase epitaxial growth layer of silicon.

[0012]

FIG. 1 is a diagram for explaining the principle of the present invention. FIG. 1 (a) is a graph showing the intensity change of the Auger spectrum of Si on an insulating film mask made of an oxide film with respect to the growth time. 1 (b) represents the thickness of the epitaxial layer grown on the surface of the silicon substrate exposed with respect to the growth time.

FIG. 2 is a process chart of an embodiment of the present invention, which shows the process of selective growth by the cross section of the substrate. A first configuration of the present invention for solving the above problem is to refer to FIGS. 1 and 2 by using an insulating film 2 formed on a semiconductor substrate 1 as a mask to form silicon on the exposed surface of the substrate 1. In a method of manufacturing a semiconductor device having a step of selectively performing vapor phase epitaxial growth, a selective growth is performed on an exposed surface of the substrate 1 within a latent period t _{s at} which silicon is not substantially deposited on the insulating film 2. Epitaxially grown layers 5, 6 of silicon
There is a step of forming the epitaxial growth layer 9 having a desired thickness by repeating the steps of growing 7 and 8 a plurality of times with a growth pause period interposed therebetween. A step of maintaining the pressure at a level of 1 / 10,000 or less during growth, and the substrate 1 at 100 ° C. to 20 ° C. higher than during growth.
At least one of the steps of maintaining a high temperature of 0 ° C. is performed, and the second configuration is the method for manufacturing a semiconductor device of the first configuration, in which the selective epitaxial growth of silicon is performed by disilane (Si ₂ H _{2 6} ) and hydrogen are used as a source gas by a low pressure CVD method, and instead of the step of the first structure performed during the growth pause period, 0.1% of fluorine or chlorine is added during the growth pause period. % To 10% hydrogen is maintained in the atmosphere.

[0014]

[Function] In vapor phase epitaxial growth of silicon, a latent period exists at the initial stage of growth even under the condition that silicon is deposited on the insulating film and is not suitable for selective growth. It is known that selective growth is performed as a result of the growth of silicon being suppressed.

The inventor of the present invention has found that the latent period is observed as a clear critical period by observing the Auger spectrum of Si on the surface of the insulating film.
This fact will be described below with reference to FIG.

FIG. 1 (a) shows the results of Auger spectroscopy of silicon deposited on an insulating film in ULPCVD of silicon, where the vertical axis represents the intensity of the Si _LMM line.
It is expressed as a ratio with the _KLL line.

With reference to FIG. 1A, it is apparent that Si does not adhere to the insulating film from the start of growth to the constant time t _s . On the other hand, referring to FIG. 1 (b), during this period, the epitaxial layer grows at a constant rate on the surface of the silicon substrate,
It shows that it is growing selectively.

However, when a certain time t _s has passed from the start of growth, the spectrum of silicon on the insulating film suddenly became strong, indicating that the deposition of silicon on the insulating film started. On the other hand, the growth rate on the surface of the silicon substrate does not change.

This observation result shows that silicon on the insulating film
Incubation period t when deposition is critical_sHave _,Before this incubation period
It is a period for forming growth nuclei and silicon is not deposited on the insulating film.
Though_,Immediately after this period, the insulating film
It reveals that the deposition of recon begins.

The present invention was devised based on the above facts.
That is, referring to FIG. 2, in the present invention, the first epitaxial growth layer 5 is selectively deposited within the latent period which is the period for forming the growth nuclei on the insulating film.

Then, the growth is stopped, the equilibrium state between the growth nuclei and the atmosphere is broken, and the growth nuclei are maintained in a state of disappearing. As specific means for breaking such equilibrium, a method of irradiating ultraviolet rays, a method of reducing the pressure of an ambient, there is a method of high temperature than the growth temperature of the substrate, and if the growth atmosphere does not etch the growth nuclei, for example Si ₂ H _In the case of the low pressure CVD method using a mixed gas of ₆ and hydrogen as a source gas, an active gas for chemically etching, such as chlorine or fluorine, can be introduced. Since the action of these means is based on chemical equilibrium and does not exert a mechanical action such as sputtering, there is no risk of destroying the growth surface and degrading the quality of the growth layer.

The growth nuclei formed on the insulating film disappear in an unbalanced state of the growth nuclei and the atmosphere. As a result, in the process of growth after growth arrest period again, between the growth of a t _s is silicon on insulator spent in new nucleation is not deposited. Therefore, the next epitaxial growth layer 6 is selectively grown over the previously grown epitaxial growth layer 5.

By repeating this process, the growth layer 9 having a desired thickness can be selectively formed without depositing silicon on the insulating film. Further, in the present invention,
Even under the condition that the growth rate of silicon on the insulating film is high in a short time, a thick growth layer selectively grown can be obtained by repeating selective growth for a short time.
It is possible to realize selective epitaxial growth with a high growth rate.

Since it is possible to extinguish the growth nuclei by breaking the equilibrium state only within the incubation period in which deposition starts, it is necessary to measure the precise incubation period for each growth condition. The latent period t _s can be clearly known by Auger spectroscopy as described above.

[0025]

EXAMPLES The present invention will be described in detail with reference to Examples. Silicon is deposited on the quartz glass reaction tube on which the substrate is installed.
Si ₂ H with a partial pressure of 1.5 × 10 ⁻⁴ Torr as a source gas
₆ was mixed with 1 Torr of H ₂ and supplied, and selective vapor phase growth was performed.

The substrate temperature was kept constant at 750 ° C. during the entire deposition process, unless otherwise specified during the growth rest period. First, referring to FIG. 2A, an insulating film 2 made of an oxide film having a thickness of 200 nm is formed on the surface of a silicon substrate 1,
A window 3 having a linear pattern with a width of, for example, 5 μm is opened in the insulating film 2 by photoetching.

Next, referring to FIG. 2B, the substrate 1 is placed in the reaction tube, and the silicon epitaxial growth layer 5 is selectively grown at the position of the window 3 using the insulating film 2 as a mask. The growth time was, for example, 15 minutes, and the film thickness of the epitaxial growth layer at this time was 50 nm. This is shorter than the latency period t _s = 20 minutes for depositing silicon on the insulating film, which is clarified from FIG. Therefore, only the growth nucleus 4 is formed on the insulating film, and silicon is not deposited. This growth time is
It can be determined for each condition based on the incubation period that differs depending on the growth condition.

Next, referring to FIG. 2C, Si ₂ H
The supply of ₆ is stopped, and any one of the following processes for extinguishing the growth nucleus 4 during this growth stop period is performed. In addition, it goes without saying that there is no problem even if two or more processes are repeated.

(1) Irradiate with ultraviolet rays. As the light source, for example, a mercury lamp or a synchrotron orbital radiation can be used. This process has the effects that precise growth can be continued because the growth conditions are not changed, and that the present invention can be easily applied only by providing a light irradiation window.

(2) The substrate temperature is raised by 100 ° C to 200 ° C. (3) The supply of H ₂ is stopped and the vacuum, for example, 10 ⁻⁶ Torr
And The processing of (2) and (3) can be performed without preparing special equipment.

(4) H ₂ mixed gas, for example, a volume of 0.1
A gas containing 10% Cl or F ₂ is supplied into the reaction tube. All the above treatments were performed for 5 minutes.

As described above, when the growth nucleus extinction process is not performed, deposition starts on the insulating film after the latent period shown in FIG. You cannot grow.

Next, referring to FIG. 2D, the epitaxial growth layer 6 is grown under the same conditions as the epitaxial growth layer 5. Next, referring to FIG. 2 (e), Si ₂ H ₆
Is stopped, and processing for extinguishing the growth nuclei is performed during the growth stop period.

Hereinafter, the processes for epitaxial growth and extinction of growth nuclei are repeated in the same manner as above. as a result,
Referring to FIG. (F), four epitaxial growth layers 5 to
8 fills the window 3 of the insulating film 2 and grows.

Finally, the insulating film 2 is removed by etching to form a linear growth layer 9 consisting of the epitaxial growth layers 5-8. In this example, it is possible to grow a selective growth layer having a thickness of 200 nm, which could not be grown under the conventional selective growth condition of Si ₂ H ₆ partial pressure of 3.7 × 10 ⁻⁵ Pa. did it.

The growth rate is about 2 as compared with the conventional method.
It was double.

[0037]

According to the present invention, the selective growth is performed within the clarified latent period, and thereafter the growth nuclei are extinguished due to the unbalanced state, so that the silicon layer is not deposited on the insulating film. Can be grown selectively and at high speed, which greatly contributes to the performance improvement of semiconductor devices.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a process chart of an embodiment of the present invention.

[Explanation of symbols]

t _s incubation period 1 substrate 2 insulating film 3 window 4 growth nuclei 5,6,7,8 epitaxial layer 9 grown layer

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device, comprising a step of selectively vapor-phase epitaxially growing silicon on an exposed surface of a substrate (1) using an insulating film (2) formed on the semiconductor substrate (1) as a mask. in, the insulating film (2) substantially incubation period in which the silicon deposition does not occur (t _s) the substrate in (1) epitaxially grown layer of selectively grown silicon on the exposed surfaces of the top (5,
6, 7 and 8) are repeated a plurality of times with a growth quiescent period interposed therebetween to form an epitaxial growth layer (9) having a desired thickness, and ultraviolet rays are irradiated during the growth quiescent period. At least one of a step, a step of maintaining the growth atmosphere at a pressure of 10,000 times or less of that at the time of growth, and a step of keeping the substrate (1) at a temperature of 100 to 200 ° C. higher than that at the time of growth Of manufacturing a semiconductor device. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the selective epitaxial growth of silicon is performed by disilane (Si ₂
Low pressure CVD using a mixed gas of H ₆ ) and hydrogen as a source gas
In place of the step according to claim 1, which is performed during the growth quiescent period, 0.1% to 10% of fluorine or chlorine is added during the growth quiescent period.
% Of hydrogen contained in the atmosphere is maintained.