JPS6037132A - Fluidizing method of phosphorus silica glass or phosphorus boron silica glass - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to phosphorus silicate glass (hereinafter referred to as P8Gμ) adhered to a semiconductor.
1"+)t L
This is related to the fluidization method of SG.

P is mainly used to form an insulating layer on the surface of a semiconductor element.
SG-? A thin film of PBSG is deposited, and a hole of about 6 μm in diameter is provided in this thin film as an outlet for, for example, aluminum wiring. To explain this situation using Figure 1,
A boron implanted layer 1a is formed on the silicon substrate 1 to a depth d from the surface.
Further, a thin film 2 of PSG or PBSG is deposited on the surface, and a hole 2a is formed in this thin film 2, and the wiring shown in the diagram is connected to the silicon substrate 1 and taken out (through t2a). In this case, if the corners A and B of JL2a are sharp, there is a risk that the wiring will be cut at those parts. This process is called the beam flow process, but when the holes 2a'ft6 are etched into the deposited PSG or PBSG thin film 2, the corners A and B become sharp. In some cases, a reflow process is required.Therefore, in the past, one reflow process was performed using an electric furnace for 10 minutes.
By heating at a temperature of 00℃ for about 60 minutes, PSG
and PBSG were liquidated. However, when heated for a long time in this way, the impurities in the silicon substrate, boron in the above example, undergo significant thermal diffusion, making it impossible to achieve finer silicon substrates in both the planar and depth directions. There were some problems that made it unsuitable for the miniaturization of elements.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and its purpose is to produce a PSG or PBSG suitable for a one-flow process so as to prevent the diffusion of impurities in a semiconductor substrate from becoming large.
The main purpose of this method is to irradiate a semiconductor substrate with light whose main component is a wavelength that can be transmitted through quartz glass, raise the temperature, and use the heat to fluidize the P adhered to the semiconductor substrate.
When heating and fluidizing SG or PBSG,
Time t during which the semiconductor substrate is held at a temperature of 1000°C or higher
(seconds) and its temperature T (℃) is 120≦fc
T-1000) dt≦1600. Here, the integral with respect to t is T≧1000℃
Regarding the time t (seconds) held in (T-1000
)(℃) means the integrated value.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic explanatory diagram of a light irradiation furnace for carrying out the present invention, in which numeral 6 indicates a long rod-shaped non-rogen incandescent lamp;
is a mirror, and both the light bulb 3 and the mirror 4 are sufficiently cooled by a cooling mechanism such as water cooling or air cooling. Reference numeral 1 denotes a silicon substrate, which is supported by a trivet-shaped quartz support (not shown) in a quartz container or passage member 6 filled with a preservation gas such as nitrogen. The silicon substrate 1 is heated mainly by a halogen incandescent light bulb 3 to raise its temperature.

Figure 5 shows an example of a heating temperature rise curve for a substrate, in which 4 x 1015/- boron ions were implanted at an implantation energy of 40 KeV into a <100> n-type silicon substrate with a diameter of 4 inches and a thickness of about 0.5 mm. What you typed, it takes 1.5 seconds to
Figure 4 shows the time-temperature progression when the temperature was raised to 1,160°C, held at 1,160°C for about 4 seconds, and then heating was stopped, and the fluidized state of PSG in that case.

This Figure 4 is a sketch of an SEM photograph of the cross section of the substrate 1, in which the thin film 2 is made of PSG containing 7% by weight of phosphorus.
was vapor-deposited, and the holes 2a were made by etching. And (a) is the state before the glue flow step, (
B) The state after the first beam flow process is shown. In the state of (A), the corners A and B are sharp, and as mentioned above, there is a very high risk that the wiring will break.

On the other hand, in the state (b), the corners A and B are fluidized and rounded, and almost no disconnection occurs.

This state (b) corresponds to the case where the temperature is maintained at 1000°C for about 20 minutes when carried out in one reflow process using the conventional electric furnace method, and in this case, the pn junction depth was α66 μm before heating. However, in the above example, the diameter was 45 μm after heating, and in the end, boron diffusion was suppressed to about half that of the conventional electric furnace method, while PSG It turns out that it is possible to obtain the same level of fluidization.

By the way, in the present invention, as can be understood from the above embodiments, the temperature of the semiconductor substrate is raised almost instantaneously in a short time using light transmitted through the quartz container, and
Although the high temperature is held for a short period of time, compared to the conventional electric furnace method, when attempting to fluidize PSGt with sufficient diffusion suppression, it is better to shorten the holding time if the high temperature holding temperature is not sufficient. It was found that if the high temperature holding temperature is low, the holding time can be extended to some extent, and it is better to extend the holding time.As a result of intensive research, in the present invention, as a result of intensive research, we have found that it is possible to extend the holding time to a certain extent if the high temperature holding temperature is low. The integral value of the temperature measured from 1000°C during the exposure time (area shown with diagonal lines in Figure 6), that is, fCT-1000) dt = $
C'C・sec), T is the temperature of the substrate in °C, and t is 1
It has been found that it is best to measure the temperature in terms of the time (in seconds) during which it is exposed to temperatures of 000°C or higher. In addition, the temperature at this time is 0.5fi in diameter.
The temperature is measured by contacting a chromel/alumel thermocouple that has been oxidized and blackened to the substrate. The depth of the pn junction was investigated by changing the value of f above to show the degree of fluidization and the degree of diffusion of impurities. In the electric furnace method, f increases by more than 200 inches, but in the present invention, the value of f increases by 160
It was confirmed that if it is less than 0, the increase will be only about 60 inches, which can fully meet the demands for finer crystals. In addition,
In the heating example shown in FIG. 6, the value of f is approximately 760, and pn
The depth increase rate of the bond is about 25 inches. On the other hand, if the value of f is too low, fluidization will be insufficient, but the lower limit is 1
20 or more is required; if it is smaller than this, there is a great risk that the wiring will break. In the end, if 120≦f≦1600, there is almost no risk of the wiring breaking, and it can meet the demands for finer crystals. I was pretty sure that it would happen.

Furthermore, when we performed the same test on PSG (PBSG) containing boron, we found that 120≦f≦
Good results were obtained in the range of 1600.

As can be understood from the embodiments described above, the present invention is a method for fluidizing PSG or PBSG for forming an insulating layer on a semiconductor substrate, which has conventionally been carried out using an electric furnace method. In view of the fact that the conventional fluidization method cannot keep up with the recent trend toward miniaturization of semiconductor devices, this new fluidization method was developed through intensive research. This method irradiates a semiconductor substrate with light that raises the temperature of the semiconductor substrate almost instantaneously, and the heat fluidizes PSG or PBSG.
Time (seconds) maintained at 000℃ or higher and its temperature (u)
The relationship is 120≦f(T-1000)dt≦1600
Compared to the electric furnace method, this method is characterized in that it is carried out while suppressing the diffusion of impurities.

In addition, it can also be used as high-temperature annealing to recover crystal damage caused during ion implantation and to electrically activate ionic impurities. Heating has the advantage that a relatively shallow p-n junction can be filled in one cycle of processing and a sufficient activation flow can be achieved.

In yet another embodiment, a discharge lamp such as a flash discharge lamp may be used as the light source, and the atmosphere surrounding the substrate may be an inert material such as argon.

[Brief explanation of the drawing]

FIGS. 1 and 4 are cross-sectional views of essential parts, FIG. 2 is a schematic diagram of a light irradiation needle, and FIG. 6 is an example of a heating temperature rise curve of a semiconductor substrate. 1... Semiconductor substrate 1a... Ion implantation layer 2...
・Glass thin film 2a...hole 6...lamp 4...
Mirror A, B...Kakube Applicant Ushio Inc. Agent Patent Attorney Toranosuke Tahara Figure 3 Time (ψ Figure 4

Claims (1)

[Claims] In irradiating a semiconductor substrate with light whose main component is a wavelength that can be transmitted through quartz glass to raise the temperature, and using the heat to heat and fluidize the phosphorus silicate glass or phosphorus borosilicate glass adhered to the semiconductor substrate, The relationship between the time t (seconds) during which the semiconductor substrate is held at a temperature of 1000°C or higher and the temperature T (°C) is 120≦fcT-1000) dt≦1600
A method for fluidizing phosphosilicate glass or phosphoborosilicate glass, characterized in that the method is characterized in that it is made as specified in