JPH01212444A - Manufacture of glass thin film - Google Patents

Abstract

PURPOSE:To obtain a glass thin film having a superior evenness at a low temperature by a method wherein a semiconductor substrate with an Si oxide film formed on its surface is placed on the electrode on one side of a pair of parallel- plate electrodes in a sealed container, doping gas is filled up into the container and plasma is generated in this gas. CONSTITUTION:An Si oxide film 11 is formed on the surface of a semiconductor Si substrate 12 and, thereafter, this substrate is placed on the electrode 1B on one side of a pair of parallel-plate electrodes 1A and 1B provided in a sealed container 9 and the temperature of the substrate 12 is held at a prescribed temperature of 400 deg.C or lower. Moreover, atmospheric gas 4 obtainable by diluting doping gas containing phosphorus, boron or arsenic is filled up into the container at a prescribed pressure and a DC voltage is applied to the electrode pair to generate plasma in the atmospheric gas by glow discharge. Thereby, the plasma decomposes dopant gas and at the same time, uniformizes the concentration of active molecules generated, the active molecules generated by the plasma are diffused in the SiO2 film 11 at a low temperature of 400 deg.C or lower and a PSG (BSG, AsSG) thin film 13 can be formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a glass thin film, and particularly relates to a method for manufacturing a glass thin film.
The present invention relates to a method for producing a glass thin film with excellent uniformity at a low temperature of C or lower.

[Conventional technology]

Phosphosilicate glass (
Phospho-3ilicate Glass, P
(abbreviated as SG).

Boron silicate glass (Boron-3ilicat)
e GIass+BSG) or arsenic silicate glass (＾rsenic-3ilicaLe Gla
Glass thin films such as ss;' A s S G ) are mainly used for the purpose of gettering. This getter action is intended to capture harmful impurity elements introduced during the semiconductor manufacturing process and protect the element formation region in the substrate from harmful impurities.

Conventionally, the following methods have been used to manufacture glass thin films. The first method is to form a thermal oxide film on a semiconductor substrate and then perform heat treatment in a gas containing phosphorus. The second method is to apply POCIs or the like onto a thermally oxidized layer, and use this as a solid phase source to simultaneously flow a dopant gas containing heat-treated elements to form a glass film.

[Problem to be solved by the invention]

However, in the first method and the second method,
There is a drawback that the heat treatment temperature is high, which adversely affects the formed semiconductor elements, and the third method is
Since glass formation is carried out at a low temperature of ~400°C, there is no above disadvantage, but there is a problem that phosphorus, boron or arsenic is not uniformly contained in the glass due to non-uniformity of gas concentration or heat distribution. There is a point.

This invention was made in view of the above points, and its purpose is to
The object of the present invention is to provide a method for manufacturing a glass thin film with excellent uniformity at a low temperature by using a method that can be operated at a low temperature of .degree. C. or lower and is excellent in averaging the active molecule concentration.

[Means to solve the problem]

According to the present invention, the above purpose is to form a silicon oxide film 11 on the surface of a semiconductor substrate 12, and then place this substrate on one electrode IB of a pair of parallel plate electrodes IA and IB provided in a closed container 9. Then, the temperature of the substrate 12 is maintained at a predetermined temperature of 400° C. or less, and the fecal gas 4, which is a diluted doping gas containing phosphorus, boron, or arsenic to be introduced into the substrate, is introduced into a closed container at a predetermined pressure. This is achieved by applying a DC voltage to the electrode pair and generating plasma in the air gas by glow discharge.

The silicon oxide (Sing) film is formed by a plasma CVD method or the like. Doping gas is phosphine (PHs)
In addition to inorganic gases such as , diborane (BtHi), and arsine (85Hi), organic metal compound gases can also be used. Argon, helium, nitrogen, hydrogen, etc. are used for dilution. Crystalline as a semiconductor substrate.

Amorphous silicon is used. The plasma decomposes the dopant gas and introduces the target element into the SiO film.

[Effect]

The plasma has the effect of decomposing the dopant gas and making the concentration of the generated active molecules uniform.

Active molecules generated by the plasma can diffuse into the 5iO1 film at low temperatures below 400°C.

At temperatures below 400°C, solid solution oxygen in silicon is not activated.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 is an explanatory diagram of a manufacturing method according to an embodiment of the present invention. Flat plate electrodes IA and IB are provided in the closed container 9. A silicon substrate 12 is placed on the flat plate electrode IB on the cathode side. The silicon substrate 12 is heated by the heater 8 to a predetermined temperature of 400° C. or less.

The effluent gas 4 is introduced into a closed container 9 through a gas flow rate regulator 5. A vacuum evacuation device 6 controls the gas pressure inside the closed container to a value of several TorrO via a gas pressure regulator 7.

A DC voltage is applied from a DC power supply 3 to the flat plate electrodes IA and IB. The plasma is the electrode IA.

Occurs between 18 and 18.

A glass thin film is prepared as follows using the above plasma generation method. Air gas 4 is used to form silicon oxide*ti on the silicon substrate 12.
As monosilane gas (Sin4) and water vapor (II
A mixed gas of O) is used. Gas pressure is l Tor
It is r. The substrate temperature is 250 to 400℃ by heater 8.
controlled by. A DC voltage is applied to generate plasma, and a Si0g film is grown to a thickness of 2 μm on the silicon substrate. The results are shown in Figure 2(a). Phosphorus, boron, or arsenic is introduced into the Si0g film as follows. To introduce phosphorus, use phosphine (pHs) as the fecal gas 4.

In the case of boron, diborane (Btlt) and in the case of arsenic, arsine (AsHs) were diluted with hydrogen gas.
000p, - used as concentration. The substrate temperature is 200
``C.''l Torr is selected as the effluent gas pressure.

A DC voltage of 800v is applied for 3 minutes. In this way, phosphorus, boron or arsenic is
~0.5# - PSG, BSG introduced to depth.

An As5Gfjl film is formed. The concentration is about IQ! ! Atom/C-. This corresponds to a molar concentration of several percent. The results are shown in Figure 2(b). Although the glass thin film is extremely thin, the getter effect of impurities can be observed anywhere on the substrate. This proves that the concentration of doping elements such as phosphorus is uniform.

〔Effect of the invention〕

According to this invention, after forming a silicon oxide film on the surface of a semiconductor substrate, this substrate is placed on one electrode of a pair of parallel plate electrodes provided in a closed container, and the temperature of the substrate is set to 40°C.
The airtight container is maintained at a predetermined temperature of 0° C. or less, and a diluted doping gas containing phosphorus, boron, or arsenic to be introduced into the substrate is filled in a sealed container at a predetermined pressure, and a DC voltage is applied to the electrode pair. Since plasma is generated in the air gas by glow discharge, phosphorus, boron, or arsenic can be uniformly doped into silicon oxide at a low temperature of 400° C. or less. Furthermore, if the silicon oxide film is formed at a low temperature using the plasma CV1) method, the entire glass thin film manufacturing process can be performed at a low temperature. It becomes possible to insert the glass F# film manufacturing process at any manufacturing process stage without changing the distance or melting and damaging the electrodes, improving the degree of freedom in the semiconductor manufacturing process.

Furthermore, since the doping of phosphorus, boron, arsenic, etc. occurs uniformly, the gettering effect of impurities is uniform and the yield of semiconductor device manufacturing is improved. Furthermore, since the method according to the present invention is a doping method using plasma, plasma CVD equipment often used in semiconductor manufacturing can be used as is, and the semiconductor manufacturing process can be simplified.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a method according to an embodiment of the present invention, and FIG. 2 is a side view showing a manufacturing process of a glass thin film. IA, IB... flat plate electrode, 3... DC power supply, 4...
・Funny gas, 5...gas flow! Regulator, 6... Vacuum exhaust device, 7... Gas pressure regulator, 8... Heater, 9... Sealed container, 11... Silicon oxide film, 12...
...Silicon saw board, Fig. 2

Claims (1)

[Claims] 1) After forming a silicon oxide film on the surface of the semiconductor substrate,
This substrate is placed on one electrode of a pair of parallel plate electrodes provided in a sealed container, the temperature of the substrate is maintained at a predetermined temperature of 400°C or less, and phosphorus, boron, or arsenic to be introduced into the substrate is A glass thin film characterized in that a sealed container is filled with a doping gas diluted with a doping gas in a sealed container, and a DC voltage is applied to the electrode pair to generate plasma in the fume gas by glow discharge. manufacturing method.