JPH02137324A - Manufacturing method of semiconductor device - 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] [Summary] Regarding a method for manufacturing a semiconductor device, particularly a method for forming an isolation region between elements using a field insulating film by selective oxidation, semiconductor crystals near the edge of a field insulating film by thermal oxidation are provided. Field insulating film formed by selective oxidation with the aim of reducing junction leakage current by relieving the stress applied to the junction, suppressing the occurrence of dislocations and crystal defects [Industrial application field] This book The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming an isolation region between elements using a field insulating film by selective oxidation.

In recent years, with the miniaturization and high integration of semiconductor devices, the negative effects on device characteristics caused by distortion in the periphery of each device region, that is, in the cell, i.e., the end of the device bone M8i region and the region adjacent to the end, have been ignored. It has become necessary to alleviate the distortion in the above region.

[Conventional technology]

When performing isolation between a plurality of semiconductor elements formed in a semiconductor device, a method of forming inter-element isolation regions using a selective oxidation method commonly referred to as a LOCOS method is often used.

Conventionally, a semiconductor device having an element quantity of 1 itl 91 region due to the above-mentioned selective oxidation has been formed by the method described below with reference to FIGS. 5(a) to 5(d).

Refer to FIG. 5(a). That is, a silicon dioxide (St(h) film 2 for a pad is formed on a semiconductor substrate, for example, a p-type silicon (Si) substrate l, and a silicon nitride (SiJ4) film 3 is formed on it. S, S
A resist pattern 4 corresponding to the device area is formed on the i3N4 film 3, and using this resist pattern 4 as a mask, the exposed 5iJ4 film 3 and the Si0g film 2 for pads below it are removed by etching, and the device is formed as shown in the figure. A laminated pattern of the pad Si0g film 2, the Si3N4 film 3, and the resist pattern 4 covering the formation region is formed, and using this laminated pattern as a mask, boron ions (B4) for forming the channel cut region are ion-implanted (105). is B° injection area)
.

Refer to FIG. 5(b) Next, after removing the resist pattern 4, thermal oxidation is performed using the 5iJa film 3 as a mask to form a field Si0g film 6 with a thickness of about 5000 to 6000 on the exposed S1 substrate 1 surface. do. At this time, the end of the field Sin and the film 6 is formed by digging into the lower part of the 5ilNa film 3 in a bird's beak shape (6A is a bird's beak part).

Further, the B+ implanted region 105 is activated and becomes the p channel cut region 5.

Note that the field 5iOt film 6 on the St substrate 1 is
In the vicinity of the bird's beak portion 6A, there is a field Si.
The stress between the 0g film 6 and the Si substrate 1 causes crystal dislocations and defects.

Refer to FIG. 5(C) Next, the Si oxynitride (SiON), 5iJn film 3 and pad SiO□ film 2 formed on the surface of the 5i3Ni film 3 during the thermal oxidation are removed by wet etching.

As a result, an element region 7 defined and separated by the field Si0g film 6 and the channel cut region 5 below the field Si0g film 6 is formed.

Refer to FIG. 5(d) Next, for example, in a MOS IC, an n-type region 8 becomes a source/drain region, and in a CCO image sensor, an n-type region 8 becomes a photoelectric conversion region, and as usual, a field 5iOt is formed. It is formed by selectively implanting ions of, for example, arsenic (As'') into the element region 7 using the film 6 as a mask and performing an activation process.

[Problem to be solved by the invention]

However, according to the above-mentioned conventional method, the field S
Because a large stress is applied due to the difference in thermal expansion coefficient between the i0g film 6 and the Si base substrate color, dislocations and crystal defects are likely to occur in the Si substrate in that region, and the n° type photoelectric conversion occurs in the element region 7. When a pn junction is formed by the region 8 etc., the generation caused by the dislocations and crystal defects in the depletion layer in the vicinity of the end of the field Sing film 6 is
The on-recombination current causes a reverse leakage current in this junction.

The reverse leakage current density of this pn junction is determined by the peripheral The leakage current density tends to increase rapidly as the ratio of length to junction area increases. This indicates that the reverse leakage current is greatly influenced by dislocations and crystal defects around the device region.In the future, as semiconductor devices become even smaller and more highly integrated, When the value of the ratio of the junction area to
For example, in the CCO image element, there has been a problem in that dark current failure occurs due to the above-mentioned leakage current.

Therefore, an object of the present invention is to alleviate the stress applied to the semiconductor crystal near the edge of the field insulating film due to thermal oxidation, suppress the generation of dislocations and crystal defects, and reduce junction leakage current. .

[Means to solve the problem]

The above-mentioned problem is solved by a method for manufacturing a semiconductor device according to the present invention, which includes a step of selectively irradiating an energy beam to the edge of a field insulating film formed by a selective oxidation method and the semiconductor substrate surface in contact with the edge vicinity. Ru.

[For production]

FIG. 1 is a diagram explaining the principle of the present invention.

In the present invention, as shown in the figure, after a field insulating film, that is, 5iO115!6, is formed on one surface of a semiconductor crystal, for example, an St substrate, by selective oxidation, the energy transmitted through the insulating film and absorbed by the semiconductor is For example, by laser beam LB, the field Sin, the edge of the film 6 and the area near the edge, for example, Si in the region in contact with the bird's beak 6^, are
The substrate 1 is scanned through the field SiO□ film 6, and this region is sequentially rapidly heated and cooled to a high temperature comparable to that during thermal oxidation, thereby changing the lattice constant of the Si substrate 1, that is, the Si crystal in this region, to the field Si0g film. 6, and the stress generated between the insulating film and the semiconductor crystal is reduced. (In the figure, 9 is a laser generator, and 10 is a condenser lens.) This makes it possible to almost completely eliminate dislocations and defects that occur in the semiconductor crystals that are in contact with the ends and the vicinity of the ends of the field insulating film. , pn formed in this region
The leakage current of the junction is significantly reduced, the S/N ratio of the signal output of the semiconductor element is increased, and the dark current defects of the semiconductor device such as a CCD image pickup element are reduced.

(Example〕 The present invention will be specifically explained below with reference to illustrated embodiments.

FIG. 2 is a process plan view of an embodiment of the present invention, FIG. 3 is a process cross-sectional view taken along the line A-A of the same embodiment, and FIG. 4 is a Raman spectrum diagram showing the state of distortion.

Refer to FIGS. 2(a) and 3(a) When forming a semiconductor device in which a large number of n-channel MOS transistors are arranged, for example, by the method of the present invention, first, heat is applied onto a P-type Si substrate 1. Thickness 1 due to oxidation
After forming 5iO1l12 for about 000 pads,
On top of that, a thickness of about 2000 Si3N is applied using the CVO method.
A film 3 is formed, and a resist pattern 4 corresponding to the element region is formed on the 5isNa film 3 by a photo process.
Using this resist pattern 4 as a mask, reactive ion etching is performed to form the pad SiO□ film 2 and 5iJ.
A laminated pattern consisting of the La film 3 and the resist pattern 4 covering the element region 7 is formed, and boron (B1) ions are implanted into the surface of the substrate 1 using this laminated pattern as a mask. (10
5 is the B1 implantation region) See FIGS. 2(b) and 3(b). Next, after removing the resist pattern 4, 5isN4
Using the film 3 as a mask, thermal oxidation is performed in humidified oxygen at a temperature of about 1000°C to a thickness of 5000 to 6 to define the element region 7.
At the same time as forming the field SiOx film 6 of about 1,000 yen, the B implanted region 105 is activated to form the p-type channel cut region 5.

Note that here, the field 5ift film 6 on the Si substrate l
In the vicinity of the bird's beak portion 6A, there is a field Si.
The stress between the 0g film 6 and the St substrate 1 causes crystal dislocations and defects.

Refer to FIG. 2(C) and FIG. 3(C) Next, the 5iJ4 film 3 containing Si oxynitride (SiON) formed on the surface during the above thermal oxidation is removed by hot phosphoric acid treatment, and the Si0g film for the pad is removed. 2 is removed by etching with a hydrofluoric acid solution to form an element region 7 defined and separated by the field SiOx film 6 and the channel cut region 5 below it. Here, the dislocations and defects are present in the region of the field SiO□ film 6 that is in contact with the bird's beak portion 6A.

Refer to FIG. 2(d) and FIG. 3(d) Next, in the method of the present invention, in order to remove the above-mentioned dislocations and defects, the dislocations and defects generated in the laser generator 9 and the condensing lens 1 are removed.
CW laser beam L focused to a predetermined beam spot diameter at 0
By B, the edge of the field SiO□ film 6 on the entire surface of the substrate 1, that is, the surface of the Sii plate in contact with the bird's beak portion 68 is sequentially irradiated in the X direction and the X direction using an xy stage (not shown) as shown by the arrow m. Then, it is rapidly heated to a high temperature close to the temperature at which the field SiO□ film 6 was formed and rapidly cooled, thereby freezing the lattice constant of the Si crystal in this region to a value close to the lattice constant of the 5in2 film.

In addition, when irradiating with the above C-laser, the laser has a wavelength of 4.
An 88 nm argon (Ar) laser was used, and the beam spot diameter was focused to 10 μmφ. The power density of the laser irradiation part is about 10'W/cm'', and the scanning speed is 3c.
The speed was controlled at m/sec. The energy density obtained by irradiation is approximately several J/cm''.

As a result of the above laser irradiation, as shown in FIG.
The stress recovered to 520.3/cm-', which is close to the value of the normal St substrate of 520.5/cl', and when converted to stress, the stress was 1. lX109dyn/cm2 to 4.6xlO”
dyn/cm''. Therefore, after the above laser irradiation, there are almost no dislocations or defects generated in the field Sin or near the end of the film 6.

Note that this energy beam irradiation is not limited to the above-mentioned C-laser, and a pulsed laser may be used, and electron beam pulses or electron beam scanning may also be used.

After referring to FIG. 2(e) and FIG. 3(e), a gate oxide film 11 is formed on each element region 7 by a normal method, and then a communicating gate electrode 12 is formed on each element region 7, Source/drain regions 13.1 are implanted into each device region by ion implantation using the gate electrode 12 as a mask.
4 and forming source/drain wiring (not shown), etc., to complete a semiconductor device in which a large number of MOS transistors are arranged on the substrate.

As mentioned above, since almost no dislocations or defects occur in the Si substrate 1 near the edge of the field SiO2 film 6, the source/drain regions 13. The junction leakage of 14 is significantly reduced and the signal-to-noise ratio of the signal output of these transistors is improved. In addition, dark current can be reduced in COD and the like.

〔Effect of the invention〕

As described above, according to the present invention, in a semiconductor device in which an element region is defined by a field insulating film formed by selective oxidation, dislocations occur in the semiconductor crystal in contact with the edge and the vicinity of the edge of the field insulating film. Since it is possible to eliminate almost all defects and defects, the p
The leakage current of the n-junction is significantly reduced, the S/N ratio of the signal output of the semiconductor element is increased, and dark current defects in semiconductor devices such as CCDs are reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 (a) to (e) is a process plan view showing one embodiment of the present invention, and Fig. 3 (a) to (e) is A of the same embodiment. -A process cross-sectional view showing the cross section in the direction of arrow A. Figure 4 is a Raman spectrum diagram showing the state of distortion of the Si crystal. Figures 5 (a) to (d) are process cross-sectional views of the conventional method. Figure 6 is the reverse. FIG. 3 is a relationship diagram between directional leakage current and junction peripheral length/junction area. In the figure, 1 is a P-type Si substrate, 2 is a pad SiO□ film,
3 is a 5isNa film, 4 is a resist pattern,
5 is a channel cut region, 6 is a field SiO2 film, 6 is a bird's beak portion, 7 is an element region, 8 is an n° type photoelectric conversion region, 9 is a laser generator, 10 is a condenser lens, 11 is a gate oxide film, 12 is a gate electrode, 13.14 is an n+ type source/drain region, 105 is a B9 injection region, LB
indicates a laser beam, D indicates a dislocation or defect, and m indicates a laser beam scanning direction arrow. 2 books, 2 e month/l, 9 i, qt theory aR diagram 1st! !
l L/7 > Responsibility” 5. , the process plan of Fuller 1
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Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, comprising the step of selectively irradiating an energy beam to an end of a field insulating film formed by a selective oxidation method and a surface of a semiconductor substrate in contact with the vicinity of the end.