JP2001237246A - Electronic device manufacturing method and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electronic device such as VLSI/ULSI which can display a high effective gettering ability for heavy metals to improve the nondefective ratio. SOLUTION: The method of manufacturing an electronic device comprises steps of forming an Si3N4 film 2 as a mask having opened laser irradiation regions, and introducing lattice defects 8 for gettering metal impurities in the laser irradiation regions by irradiating it using an excimer laser 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electronic device and an electronic device, and more particularly to a method of manufacturing an electronic device using a semiconductor substrate, which has a sufficiently high gettering ability with respect to heavy metals. The present invention relates to a method for manufacturing an electronic device and an electronic device that can improve a non-defective product rate when manufacturing the electronic device.

[0002]

2. Description of the Related Art One of the causes of deteriorating device characteristics in electronic devices such as VLSI / ULSI is contamination of the semiconductor substrate surface by metal impurities, particularly heavy metals such as Fe and Ni. Therefore, in order to remove the metal impurities from the active layer region of the electronic device in the manufacturing process of the electronic device, it is widely practiced to form a gettering sink due to distortion or defect on the back surface of the semiconductor substrate (external gettering). Have been done. As the external gettering method, the back surface of the semiconductor substrate is damaged (Sand Blast method)
A method of forming trap sites for harmful metal impurities on the backside of a semiconductor substrate by performing a physical treatment such as a backside of the semiconductor substrate or a chemical treatment such as deposition of polysilicon on the backside of a semiconductor substrate (Poly-silicon Back Seal). Gettering), a method of forming a gettering layer in the vicinity of a device formation region, or the like.

FIG. 12 is a schematic view showing the outline of the above-mentioned backside gettering. In the figure, 1 is a silicon semiconductor substrate, 1a is a device formation region (active layer region), and 1b is a vicinity of the backside of the semiconductor substrate. Is shown.

As a method of forming a gettering layer near the device forming region 1a, an Si (Ge) layer is inserted between a semiconductor supporting substrate and an epitaxial layer, and upper and lower misfit dislocation networks are used as gettering sinks. (Fumio Shimura, "Semiconductor Silicon Crystal Engineering" (1993) Maruzen p.367), or forming an oxygen-rich, carbon-rich, or boron-rich layer between an epitaxial layer and a semiconductor support substrate to create a strain field And a method using the same as a gettering sink (JP-A-57-87119, JP-A-5-152304, etc.) have been proposed.

[0005]

A semiconductor substrate used for manufacturing an electronic device such as a VLSI / ULSI is continually increasing in diameter from the viewpoint of increasing the efficiency of the manufacturing process. This is accompanied by an increase in the thickness of the semiconductor substrate for securing the strength. For this reason, when the backside gettering is used, the metal impurity atoms A (FIG. 12) on the front surface of the semiconductor substrate are forced to move (diffuse) for a longer distance to the gettering sink 1b (FIG. 12) near the backside of the semiconductor substrate. Become. More recently, the process has been required to be operated at a lower temperature in accordance with the miniaturization of the device structure. The lowering of the process causes an increase in the deposition amount of the metal impurity atoms A and a reduction in the diffusion rate. As described above, recent advances in device manufacturing technology related to VLSI / ULSI tend to increase the difficulty of the backside gettering. For this reason, it is desired to form a gettering layer near the device formation region 1a instead of the back surface gettering.

In particular, SIMOX (Separation by
In the IMplanted Oxygen) substrate, the active layer region (device formation region) formed by recrystallization by heat treatment,
There is a BOX oxide film formed by ion implantation of oxygen between the BOX oxide film and the semiconductor support substrate. Gettering on the semiconductor support substrate side is difficult unless heavy metal impurities pass through the BOX oxide film. It is difficult for heavy metal impurities such as Fe and Ni to pass through the BOX oxide film even after heat treatment for a long time at a high temperature, so that gettering in the active layer region is required.

Further, it is difficult to form a gettering layer having a high gettering ability by using any of the above-described conventional methods of forming a gettering layer near a device formation region.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a gettering ability that is highly effective against metal impurities in a process of manufacturing an electronic device such as a VLSI / ULSI and to improve the yield rate. It is an object of the present invention to provide a method of manufacturing an electronic device and an electronic device capable of performing the method.

[0009]

In order to achieve the above object, a method (1) for manufacturing an electronic device according to the present invention comprises the steps of: forming a mask having a laser irradiation area opened; A step of irradiating a laser beam to introduce a lattice defect for gettering into the laser irradiation area. According to the electronic device manufacturing method (1), even in a SIMOX substrate where it is usually difficult to getter metal impurities such as Fe and Ni, the lattice defect which is stable even in heat treatment as a gettering sink in the active layer region. , The gettering of heavy metals can be performed in the device manufacturing process, and the yield rate can be improved.

Further, according to a method (2) for manufacturing an electronic device according to the present invention, in the method (1) for manufacturing an electronic device described above, as the mask, the Si ₃ formed by a CVD method as the mask.
It is characterized by using an N ₄ film. The Si ₃ N ₄
The film can suppress the transmittance of the excimer laser to approximately 0% and can be used as a complete mask for the excimer laser. Therefore, according to the above-described method (2) for manufacturing an electronic device, Excimer laser irradiation can be reliably performed only in the laser irradiation area, and the lattice defect is reliably introduced only in a necessary area without adversely affecting a manufactured electronic device. Can be.

In the method (3) for manufacturing an electronic device according to the present invention, the excimer laser may be irradiated with a KrF laser having a wavelength of 249 nm, -Density 3 to 10
J / cm ² · pulse, irradiation interval 50 to 220 µm, width 3
The process is performed under the condition of a linear beam of 0 to 50 μm × length of 3 to 5 cm. According to the above electronic device manufacturing method (3), a sufficient amount of gettering sink is formed in the irradiation region of the excimer laser without causing warpage of the semiconductor substrate. Gettering ability can be sufficiently exerted in the manufacturing process of (1).

An electronic device according to the present invention (1)
Is characterized in that lattice defects for gettering formed by irradiation of excimer laser are introduced into the source and drain regions. According to the above electronic device (1), even if an electronic device is manufactured using a SIMOX substrate in which gettering of metal impurities such as Fe and Ni is usually difficult, a getter is formed in the active layer region of the semiconductor substrate. By forming the ring sink, it is possible to sufficiently secure the gettering ability of metal impurities in the device manufacturing process.

An electronic device according to the present invention (2)
Is characterized in that, in the above electronic device (1), the lattice defects include stacking faults and V-type dislocations. The stacking fault and the V-type dislocation are particularly excellent in the gettering ability for metal impurities. According to the electronic device (2), the gettering ability of the metal impurities in the device manufacturing process can be made sufficiently large. it can.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for manufacturing an electronic device and an electronic device according to the present invention will be described with reference to the drawings. Note that components having the same functions as those of the conventional example are denoted by the same reference numerals. We have:
First, the SIMOX substrate was intentionally contaminated with metal impurities such as Fe and Ni, and the gettering ability of a semiconductor support substrate having an external gettering function and an internal gettering function was investigated. As a result, with respect to Fe and Ni contamination, these heavy metals cannot pass through the BOX oxide film,
Only the heavy metal was concentrated in the active layer region, and no gettering occurred.

FIG. 1 shows the spectral characteristics of the SiN film. As is apparent from this figure, the spectral characteristics of the SiN film depend on the flow ratio of the SiH ₄ gas and the N ₂ gas in the process of forming the SiN film, and when SiH ₄ / N ₂ = 0.47, the light source Is less than 400 nm, the transmittance is 0%. Therefore, the Si ₃ N ₄ formed under such conditions
It has been determined that the film can be used as a complete mask for excimer lasers, often with wavelengths below 400 nm.

Conventionally, Nd: Y has been used for laser gettering.
An AG laser has been used, but in this case, 15 J /
Thermally stable dislocations are introduced with an energy of ² cm ² or more, and a good external gettering effect is exhibited.
The spot diameter of the Nd: YAG laser was as small as 40 μm, and the low throughput was the biggest problem.

The excimer laser is an Nd: YAG laser.
Since the wavelength is shorter than that of the Nd: YAG laser (usually used at a wavelength of 1060 nm), the penetration depth of the laser light is extremely small and the energy absorption is high.

Shall generated due to heavy metal contamination
Observation of ow Pit (SP) makes it possible to evaluate the gettering ability for heavy metals. That is, when the gettering of the heavy metal is sufficiently performed, no SP is generated on the surface of the semiconductor substrate after the selective etching process, and when the gettering is not sufficiently performed, the selective etching is performed. After the etching process, SP is observed on the surface of the semiconductor substrate.

As shown in FIG. 2, an excimer laser is used to irradiate the surface of the semiconductor substrate with laser under various conditions as shown in FIG. The irradiation conditions of the laser that could obtain a sufficient gettering ability were determined from the state of occurrence. When a KrF laser having a wavelength of 249 nm is used,
Effective irradiation conditions are that the energy density is 3 per pulse.
At 〜１０10 J / cm ² , irradiation interval is 50 to 220 μm
By using a linear beam having a width of 30 μm and a length of 3 cm, a semiconductor substrate having an 8-inch diameter can be processed at a speed of 4 minutes / 1 sheet. Put was realized.

FIGS. 3 to 6 show the steps of manufacturing an electronic device incorporating the gettering ability imparting process according to the embodiment. First, oxygen is ion-implanted into the upper surface of the silicon semiconductor supporting substrate 10a pulled up and manufactured by the Czochralski method to form a BOX oxide film 10b, and an active layer 10c is formed on the BOX oxide film 10b to manufacture. Prepared SIMOX substrate 10 (FIG. 3
(A)).

The surface of the SIMOX substrate 10 is coated with Si ₃ N
₄ film 2 using the ECR-CVD method, SiH ₄ gas and N ₂
The flow rate ratio between the gas and SiH ₄ / N ₂ = 0.40-0.5
The range is 5, Si ₃ in a range of thickness 0.3~1μm
An N ₄ film 2 is formed (FIG. 3B). A resist film 3 is formed on the Si ₃ N ₄ film 2 by a spin coating method or the like (FIG. 3C), and a photolithography process is performed to form a resist pattern 3a (FIG. 3D). .

Next, an Si ₃ N ₄ film 2 using the resist pattern 3a as a mask and using CF ₄ gas as an etchant.
Then, the resist pattern 3a is removed to form a pattern 2a of the Si ₃ N ₄ film 2 (FIG. 4 (b)). Next, the Si ₃ N ₄ film 2
Using the pattern 2a as a mask, the active layer 10c is irradiated with an excimer laser 4 under the above-mentioned irradiation conditions to introduce lattice defects 8 (FIG. 4 (c)), and then used as a laser mask. The removed Si ₃ N ₄ film 2 is dissolved and removed using H ₃ PO ₄ (FIG. 4D).

Next, an oxidation process is performed on the surface of the active layer 10c to form an oxide film 5 serving as a gate oxide film.
(A)), a polysilicon film 6 serving as a gate electrode is formed on the oxide film 5 (FIG. 5B), and a resist film 7 is further formed on the polysilicon film 6 (FIG. 5B). 5
(C)). Next, a photolithography process is performed to form a resist pattern 7a (FIG. 5D).

Next, using the resist pattern 7a as a mask, the polysilicon film 6 and the oxide film 5 are etched using a mixed gas of Cl ₂ , CF ₄ and H ₂ as an etchant (FIG. 6A). Then, after ion implantation for forming a source and a drain is performed (FIG. 6B), the resist pattern 7a is removed (FIG. 6C).

By going through the above process, usually F
SIM that is difficult to getter metal impurities such as e and Ni
Also in the OX substrate 10, stable lattice defects can be introduced into the active layer 10c as a gettering sink even in the heat treatment. ECR-CV as a laser mask
By using the Si ₃ N ₄ film 2 formed by the method D, the transmittance of the excimer laser in the mask portion can be suppressed to approximately 0%, and the laser irradiation region (Si ₃ N 4
Excimer laser irradiation can be reliably performed only on the pattern opening of the _four film 2), and the lattice defect can be reliably formed only in a necessary region without adversely affecting a manufactured electronic device. Can be introduced.

The excimer laser 4 is irradiated with a KrF laser having a wavelength of 249 nm and an energy density of 3 to 10.
J / cm ² · pulse, irradiation interval 50 to 220 µm, width 3
By performing the process under the condition of a linear beam of 0 to 50 μm × length of 3 to 5 cm, the SIMOX substrate 10 is not warped and a sufficient amount is applied to the irradiation area of the excimer laser-4. By forming the gettering sink, the gettering ability can be sufficiently exhibited in the manufacturing process of the electronic device.

Also, the source and drain regions (pattern openings of the Si ₃ N ₄ film 2), which are active layer regions of the electronic device, are exposed to an excimer laser 4 to form lattice defects for gettering. Since it can be introduced, usually Fe
SIMO with difficult gettering of metal impurities such as Ni and Ni
Even an electronic device manufactured using an X substrate,
By forming a gettering sink in the source and drain regions, the gettering ability of metal impurities in the device manufacturing process can be sufficiently ensured.

The irradiation of the excimer laser-4 gives
Since stacking faults and V-type dislocations can be introduced as the lattice defects, the gettering sink can be made stable against heat treatment, and the gettering ability of metal impurities in the device manufacturing process can be made sufficiently large. Can be maintained. Therefore, through the above process, it is possible to produce an electronic device that exhibits a high gettering ability with respect to metal impurities such as Fe and Ni and that can improve the yield rate.

[0029]

Examples and Comparative Examples Electronic devices according to Examples were manufactured under the following conditions. As a comparative example, an electronic device was manufactured under the same conditions except that no excimer laser irradiation was performed.

SIMOX substrate 10 used: 8 inches, p-type B-doped Si, (100) plane used, resistance 10
20 Ω · cm Oxygen concentration 14 to 18 × 10 ¹⁷ atoms / cm ³ BOX oxide film 10b Thickness: 100 nm Active layer 10c thickness: 300 nm SiH ₄ gas and N ₂ gas when forming the Si ₃ N ₄ film 2 Flow rate ratio: 0.47 Thickness of Si ₃ N ₄ film 2: 0.3 μm Irradiation condition of excimer laser-4: Kr of wavelength 249 nm
F laser energy density 5 J / cm ² · pulse Irradiation interval 55 µm Linear beam 30 µm wide × 3 cm long 90 beam / sec beam at 5 mm / sec SIM
Scanning was performed from end to end of the OX substrate 10 and this was performed seven times (FIGS. 7 to 10). By this method, the irradiation interval of the laser irradiation region was set to 55 μm as described above. Observation confirmed that stacking faults and V-type dislocations were introduced into the irradiated region. Under the above irradiation conditions, as shown in FIG. 10, there was an electronic device region not irradiated with the laser. However, the diffusion coefficient of Fe is D = 3 × 10 ⁻⁶ cm ² / sec.
When calculating the diffusion length at 0 ° C. for 100 sec, 173 μm is obtained.
m, which indicates that even if the irradiation interval is set to 55 μm, the heavy metal can sufficiently reach the gettering sink and gettering can be performed.

After dispersing Fe by spin coating on the surface of the SIMOX substrate 10 manufactured under the conditions according to the above Examples and Comparative Examples, performing a heat treatment, and then measuring the breakdown voltage of the oxide film, the gettering ability is obtained. Was evaluated.
The results are shown in FIG.

Fe coating material: 5 ppm Fe
HNO ₃ / H ₂ O mixed solution containing Fe Coating amount: 6 × 10 ¹² atoms / cm
² Heat treatment pattern: DRAM (Dynamic Random Acc)
ess Memory) Heat treatment pattern simulating the manufacturing process As is clear from FIG. 11, in the SIMOX substrate 10 according to the example, good results can be obtained with a probability of 80%, and in the comparative example, only 5%. Good results could not be obtained. As described above, in the case of the example, it was confirmed that the gettering ability was significantly improved.

As described above, if the manufacturing process of the electronic device according to the embodiment is performed, an electronic device having high gettering ability can be manufactured, and the influence of metal impurities can be greatly reduced. .

[Brief description of the drawings]

FIG. 1 shows SiH ₄ gas and N in the process of forming a SiN film.
₉ is a graph showing spectral characteristics of a SiN film when a flow ratio with respect to _two gases is changed.

FIG. 2 is a table showing the results of an investigation on the relationship between irradiation conditions of an excimer laser and gettering ability.

FIGS. 3A to 3D are schematic cross-sectional views showing a part of a manufacturing process of an electronic device incorporating a gettering ability providing process according to an embodiment of the present invention.

FIGS. 4A to 4D are schematic cross-sectional views showing a part of a manufacturing process of an electronic device incorporating a gettering ability providing process according to an embodiment of the present invention.

FIGS. 5A to 5D are schematic cross-sectional views showing a part of a manufacturing process of an electronic device incorporating a gettering ability providing process according to an embodiment of the present invention.

FIGS. 6A to 6C are schematic cross-sectional views showing a part of a manufacturing process of an electronic device incorporating a gettering ability providing process according to an embodiment of the present invention.

FIG. 7 is a SIMO for explaining laser irradiation conditions.
It is a top view which shows an X substrate.

FIG. 8 is a laser for explaining irradiation conditions of the laser;
It is a top view showing a pulse.

FIG. 9 is a laser for explaining irradiation conditions of the laser.
It is an enlarged plan view showing a pulse.

FIG. 10 is a cross-sectional view of the semiconductor substrate showing a state in which a laser pulse is irradiated on the semiconductor substrate.

FIG. 11 is a graph showing oxide film breakdown voltage characteristics of the electronic device according to the example and the electronic device according to the comparative example.

FIG. 12 is a cross-sectional view of a semiconductor substrate showing the concept of conventional back gettering.

[Explanation of symbols]

Reference Signs List 10 SIMOX substrate 2 Si ₃ N ₄ film 2 a pattern 3 resist film 4 excimer laser 5 oxide film 6 polysilicon film 8 lattice defect

Continuing from the front page (72) Inventor Hideki Tsuya 2201 Kamida, Oita, Kihoku-cho, Kishima-gun, Saga Prefecture F-term (reference) 5F048 AA04 AA08 AB01 AC01 BA09 BC11 BG01 DB06

Claims (5)

[Claims] 1. A step of forming a mask having an opening in a laser irradiation area, and a step of irradiating an excimer laser to introduce a lattice defect for gettering into the laser irradiation area. A method for manufacturing an electronic device, comprising: 2. The method for manufacturing an electronic device according to claim 1, wherein an Si ₃ N ₄ film formed by a CVD method is used as said mask. 3. The irradiation of the excimer laser is performed at a wavelength of 2
49nm KrF laser, energy density 3-10J
/ Cm ² pulse, irradiation interval 50-220 μm, width 30
3. The method for manufacturing an electronic device according to claim 1, wherein the method is performed under the condition of a linear beam having a size of about 50 .mu.m.times.3 to 5 cm. 4. An electronic device characterized in that gettering lattice defects formed by excimer laser irradiation are introduced into the source and drain regions. 5. The electronic device according to claim 4, wherein said lattice defects include stacking faults and V-type dislocations.