JPH01128527A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce damages of elements formed on a substrate and to further highly integrate a semiconductor device easily by heating a reflow in a pressure atmosphere. CONSTITUTION:A pressure chamber 11 in which a substrate 1 is disposed and its atmosphere is pressurized to 10atm is composed at a wall facing the surface of the substrate 1 of a thick quartz glass plate 12 having approx. 25mm of thickness, heating lamps 13 are disposed at its outside, and a reflecting plate 14 is disposed at its outside. A plurality of the lamps 13 are aligned in a rod state in such a manner that the upper and lower lamps are crossed perpendicularly to each other. The chamber 11 for forming the pressure atmosphere of a reflow is pressurized by supplying nitrogen from a high pressure nitrogen gas cylinder 15 through a regulator 16 and an auxiliary tank 17. Numeral 18 denotes a valve disposed suitably in a nitrogen supply passage, and numeral 19 denotes a pressure gauge for monitoring the pressure in the chamber 11. The reflow is heated by turning ON the lamps 13, and its heating temperature and time are controlled by controlling supply power and lighting time.

Description

[Detailed Description of the Invention] [Summary] A semiconductor device in which an insulating film made of a silicon oxide film doped with impurities and having an uneven surface on a semiconductor substrate is subjected to heat treatment (reflow) to smooth the surface. Regarding the manufacturing method, the heating is performed in a pressurized atmosphere for the purpose of shortening the heating time or lowering the temperature.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and in particular to a heat treatment to smooth the surface of an insulating film made of a silicon oxide film doped with impurities and having an uneven surface on a semiconductor substrate. .

In a semiconductor device, an insulating film is provided on a substrate, and wiring is formed on the insulating film. The insulating film is made of silicon oxide film doped with impurities, such as PSG (phosphorus glass) or BPSG, to prevent the wiring from becoming unstable if the surface becomes uneven due to the gate electrode being located below or an electrode window being provided. Heat treatment (reflow) is performed to lower the melting point using materials such as (borophosphorus glass) and to make the surface smooth.

[Conventional technology]

FIG. 4 is a side sectional view explaining the beam flow.

In the figure, 1 is a semiconductor substrate, 2 is a convex portion such as a gate electrode formed on the substrate l, and 3 is a silicon oxide film doped with impurities deposited by, for example, CVD (chemical vapor deposition). This is an insulating film to be reflowed.

The convex portion 2 is patterned and formed on the substrate 1, and the side surface forms a step 2a.

As a result, the surface of the insulating film 3 after being deposited becomes uneven following the convex portions 2, as shown in FIG.
In the part a, the thickness of the lower side also tends to be thinner than that of the upper side. Therefore, if a wiring is formed directly on this, the wiring is likely to be disconnected at the step 2a.

Therefore, the insulating film 3 is heated so that it becomes semi-molten and partially flows, making the surface smooth as shown in Figure (bl).This heating treatment is reflow. If the slope α (herein α is referred to as a reflow angle) of the surface step 2a is set to about 30 degrees, for example, the wiring formed thereon will be stable.

Further, although not shown, even when an electrode window is provided in the insulating film 3, a step is formed in that portion, similar to the above, and the application of reflow is effective.

By the way, conventional glue flow is performed by heating under normal pressure.

Therefore, if the height of the step 2a and the thickness of the insulating film 3 are each about 1 μm and the reflow angle α is about 30 degrees, in the case of PSG, the temperature is 1000°C for 30 minutes to 1050°C.
B, which has a lower melting point, requires heating for about 10 minutes.
Even in the case of PSG, 900℃ 30 minutes to 950℃1
Approximately 0 minutes of additional time is required.

[Problem that the invention seeks to solve]

However, the combination of temperature and time in the reflow process causes the diffusion region of the element formed on the substrate 1 to be further diffused due to the high temperature or long time, thereby deteriorating the characteristics of the element. This effect becomes a problem especially when the degree of integration of semiconductor devices increases.

[Means for solving problems]

The above problems are solved by the manufacturing method of the present invention, which performs reflow heating under a pressurized atmosphere.

[Effect]

Based on extensive experience, the present inventor has determined that by performing reflow heating under a pressurized atmosphere, the same reflow angle α can be achieved in a shorter time or at a lower temperature than when heating under normal pressure. I found what was enough.

The present invention utilizes this phenomenon, thereby reducing the influence on the characteristics of elements formed on the substrate.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a characteristic diagram of an example of reflow using a pressurized atmosphere, and FIGS. 2 and 3 are configuration diagrams of examples of apparatus for carrying out the first and second embodiments, respectively.

FIG. 1 is a reflow angle α-heating temperature characteristic diagram using atmospheric pressure and heating time as parameters for one example of the configuration shown in FIG. 4. The insulating film 3 is BPSG containing 4 wt% boron and 5 wt% phosphorus, and the step 2a
The height of the insulating film 3 and the thickness of the insulating film 3 are each about 1 μm.

According to the figure, if the pressure is increased to 10 atm, the reflow angle α can be set to about 30 degrees at 950° C. for 3 minutes, and if the pressure is increased to 1100 atm, the reflow angle α can be set to about 30 degrees at 450° C. for 1 minute. In the former, the heating time has been shortened from the conventional 10 minutes to 3 minutes, and in the latter, the heating time has not only been further shortened (the heating temperature has also been significantly lowered.) It is clear that lowering the temperature reduces the negative effects on devices formed on the substrate.

Note that although the above-described flow characteristics are obtained when the insulating film 3 is made of BPSG, a similar tendency is exhibited when the insulating film 3 is made of PSG.

The pressure is applied to 10at+w and the flow (first example) is as follows:
This can be carried out using the apparatus shown in FIG.

In Figure 2, the substrate l is placed and the atmosphere is set to 10 atm.
The pressure chamber 11 that is pressurized has a wall facing the surface of the substrate 1 (
It is composed of a thick quartz glass plate 12 with a thickness of about 25 mm,
A heating lamp 13 is placed on the outside of the heating lamp 13, and a reflector 1 is placed on the outside of the heating lamp 13.
4 are arranged. A plurality of lamps 13 are arranged in a bar shape, and the upper and lower sides are arranged perpendicularly to each other.

The pressurization of the pressure chamber 11 that forms the pressurized atmosphere for reflow is as follows:
This is carried out by supplying nitrogen from a high-pressure nitrogen cylinder 15 via a regulator 16 and an auxiliary tank 17. Reference numeral 18 indicates pulp appropriately placed in the nitrogen supply path, and reference numeral 19 indicates a pressure gauge for monitoring the pressure within the pressure chamber 11.

Heating for reflow is performed by lighting the lamp 13, and the heating temperature and heating time are controlled by controlling the supplied power and lighting time.

Further, pressurization to 1100 at and flow (second embodiment) can be carried out using the apparatus shown in FIG.

In FIG. 3, the substrate 1 is placed and the atmosphere is set at 1100a.
The pressure chamber 21 pressurized to t is spherical so as to withstand high pressure. A heating heater 22 is arranged inside the pressure chamber 21,
A substrate 1 is placed thereon. This heater 22 has a small heat capacity to improve heating responsiveness.

The pressurization of the pressure chamber 21 that forms the pressurized atmosphere for reflow is as follows:
This is carried out by supplying nitrogen from a high-pressure nitrogen cylinder 25 via a regulator 26 and an auxiliary tank 27. Reference numeral 28 represents a pulp appropriately placed in the nitrogen supply path, and reference numeral 29 represents a pressure gauge for monitoring the pressure within the pressure chamber 21.

Heating for reflow is performed by supplying power to the heater 22, and the heating temperature and heating time are controlled by controlling the supplied power and power supply time.

〔Effect of the invention〕

As explained above, according to the configuration of the present invention, in a method for manufacturing a semiconductor device, particularly in reflowing an insulating film made of a silicon oxide film doped with impurities and having an uneven surface on a semiconductor substrate, This has the effect of making it possible to shorten the heating time or lower the temperature, reduce damage to elements formed on the substrate, and facilitate higher integration of semiconductor devices.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram of an example of reflow using a pressurized atmosphere, Fig. 2 is a block diagram of an example of an apparatus for carrying out the first embodiment, and Fig. 3 is a block diagram of an example of an apparatus for carrying out the second embodiment. FIG. 4 is a side sectional view explaining the beam flow. In the figure, 1 is a semiconductor substrate, 2 is a convex portion, 3 is an insulating film, 11.21 is a pressure chamber, 12 is a quartz glass plate, 13 is a heating lamp, 14 is a reflection plate, 22 is a heating heater, 15.25 is a high pressure nitrogen cylinder, 16.26 is a regulator, 17.27 is an auxiliary tank, 18.28 is pulp, 19.29 is a pressure gauge, and α is a reflow angle. Sofof! Ebi BA Suzuj! ψh Gengo Ashi 4 Hatakemachi

Claims (1)

[Claims] When performing heat treatment to smooth the surface of an insulating film made of a silicon oxide film doped with impurities and having an uneven surface on a semiconductor substrate, the heating is performed under a pressurized atmosphere. A method for manufacturing a semiconductor device.