JPS5810831A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To recover the property of an insulating film, to which ions are irradiated, and to improve yield on production of the semiconductor device by annealing the insulating film by a laser. CONSTITUTION:A field oxide film 2 is formed to the surface of a P type silicon substrate 1 and an element forming region is demarcated, a gate oxide film 3 and a gate electrode 4 are shaped to the element forming region, an N type impurity (As) 5 is introduced through an ion implantation method while using the field oxide 2 and the gate electrode 4 as masks, and source and drain regions 6, 7 are shaped. Laser beams 8 are irradiated, and scanned (an arrow lin 9) extending over the whole region of the field oxide film 2, thus annealing the field oxide film 2. The normal manufacturing process is conducted successively. Accordingly, various characteristics (such as an etching rate and the like) of the field oxide film are recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of restoring properties of an insulating film that have been changed by ion implantation.

In recent years, the ion implantation method has been widely used in the manufacturing process of semiconductor devices such as L8I, super I, and 8I, but the insulating film that is irradiated with ions in this ion implantation process has an increased etch rate with respect to chemicals and a refractive index. Phenomena such as a change in the voltage or a drop in withstand voltage occur, resulting in numerous inconveniences.

For example, in the manufacturing process of MOS FACT, a field oxide film is formed on the surface of a P-type silicon substrate to define an element formation region, a gate electrode is provided in this element formation region, and then the field oxide film and gate electrode are masked. Arsenic (As) is injected into the silicon base and surface using the ion implantation method, followed by a pretreatment process in which the substrate surface is cleaned by a method such as treatment with chemicals, and then annealed in a high-temperature furnace. , the implanted As is activated to form source and drain regions. During this time, the above field oxidation g*Fi
After the ion implantation, the etched rate increases, and the thickness is significantly reduced by the FluorilcHF)-based etchant used in the next pretreatment step. Therefore, there is a problem that the production yield and reliability of semiconductor devices are reduced.

The properties of the insulating film that have changed due to the above-mentioned ion implantation can be almost recovered by the subsequent high-temperature annealing process, but this is because the above-mentioned pretreatment process must be performed before the high-temperature annealing process. It does not contribute in any way to eliminating the track mark.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device in which the properties of an insulating film that have changed due to ion implantation can be restored prior to subsequent steps.

A feature of the present invention is that after the ion implantation step, a step of annealing the ion-irradiated insulating film by irradiating it with a laser beam is added, and subsequent steps are then performed.

0IIh1 An embodiment of the present invention will be explained below with reference to drawings.
Figures 1 to 8 are side views of main parts showing one embodiment of the present invention, and 1! The top view of FIGS. 4(a) to 4(C) are curve diagrams showing the effects of the above embodiment.

In FIG. 1, a silicon substrate of IFiPm, a field saponification film of 2nd Company, a gale oxide film of 8th Company, 4 is a gate electrode, and a field oxide M2 is formed on the surface of a P-type silicon substrate 1 to define an element formation region. After forming a gate oxide film 8 in this element formation region and a gate electrode 4 thereon,
The above field oxide film 2 and gate 1! Acceleration voltage is approximately 150 (Key) by ion implantation using Key 4 as a mask.
Arsenic (As) of approximately t2X10 (01'') is implanted into the surface of the silicon substrate 1 (arrow line 5). In the same figure, this is the region where 6 and 7 FiAs are implanted.

In the above process, the field oxide film 2 is used as a mask to prevent As ions from being implanted into the surface of the silicon substrate at the relevant portion, and is therefore directly irradiated with ions. As a result, the properties of the field oxide film 2 change, such as a significant increase in the etching rate for HF.

Therefore, as shown in FIG. 2, the field oxidation film 2 is annealed by irradiating a laser beam 8 and scanning the entire field oxide film 2 (arrow [9)]. In carrying out this laser annealing, in this practical example, the silicon substrate 1 is heated to approximately 500 mA, and a continuous wave type argon (Ar)-poor laser is used, with an output of approximately tBw. 4 scan speed is about 10
[cM/sec], overlap of scanning trajectories is approximately 80 [%]
] was selected.

Among the above conditions, the reason for heating the substrate l by IJu is to compensate for the lack of laser output, and it is also possible to omit substrate heating by using a high-output laser, or to use a pulse oscillation type laser. is also possible, but the surface of the insulating film after laser annealing may be roughened, so it seems preferable to use a continuous wave laser.

The amount of overlap between the scanning trajectories is the ratio of the overlap width of two adjacent scanning trajectories to the radius W of the two adjacent scanning trajectories, as shown in FIG. %] or more, preferably about 80[%] or more, the field oxide film 2
almost recovers to its original properties. Therefore, the subsequent steps can be carried out according to the usual manufacturing method, i.e. using hydrofluoric acid (HF).
The regions 6 and 7 are each formed as a source region by performing pretreatment with a chemical, followed by high-temperature annealing to activate the aforementioned implanted S.

Even if the +M@process using HF-based chemicals is performed in this manner, the thickness will not be excessively reduced because the field oxidation J1211 has already recovered to its normal value in the etched rate in this embodiment.

Next, the effects of this embodiment will be explained using FIGS. 4(a) to 4(C). Figures (a) to (C) are curve diagrams showing the infrared absorption characteristics of the SiO□ film at each stage. The above sample was laser annealed under the conditions described above and at a temperature of approximately 1000 L°C in a nitrogen (N2) atmosphere.
] Although high temperature annealing was performed for about 80 [minutes], the infrared M
Shows absorption properties.

When 71s ions are implanted, remarkable absorption characteristics appear at a wavelength of 10.1 L μm, as shown in FIG. When this is subjected to laser annealing or high-temperature annealing as described above, the remarkable absorption characteristics disappear in both Φ) and (C) of the same figure, and moreover, both exhibit the same absorption characteristics. This shows that the properties of the 5in2 film can be recovered to almost the same extent as when high temperature annealing by laser annealing is performed. On the other hand, it is well known that the above-mentioned high-temperature annealed Si0g film has properties such as etching rate that are almost the same as before ion implantation. Therefore, it is understood that the various properties of the field atomized film 2 of this example, which was laser annealed immediately after the ion implantation process, were able to be recovered to at least the same extent as when high temperature annealing was performed. It will be.

As explained above, according to the present invention, it is possible to restore silk properties that have been changed by ion implantation prior to performing subsequent steps. Therefore, the manufacturing yield and reliability of semiconductor devices are improved.

It goes without saying that the present invention is not limited to the above-mentioned embodiment and can be applied to any insulating film.

[Brief explanation of drawings]

Figures 1 to 8 are diagrams showing an embodiment of the present invention, in which Figures 1 and 2 are sectional views of the main parts, Figure 8 is a top view of the main parts showing the scanning locus of the laser beam, and Figure 4 is a top view of the main parts showing the scanning locus of the laser beam. Figures (a) to (C) are curve diagrams showing infrared absorption characteristics for explaining the effects of the above embodiment. In the figure, 1 is the semiconductor substrate, 2 is the field (0).

Claims (1)

[Claims] In a method for manufacturing a semiconductor device, which includes a step of implanting predetermined ions into a semiconductor substrate having an insulating film on its surface, the insulating film that has been irradiated with ions in the ion implantation step is irradiated with a laser during the ion implantation step. 1. A method of manufacturing a semiconductor device, comprising adding a step of annealing by irradiating a beam, and then performing subsequent steps.